JP5964701B2 - Brake device - Google Patents

Description

  The present invention relates to a brake device that applies a braking force to a vehicle such as an automobile.

  Disk brakes and drum brakes are known as brake devices provided in vehicles such as automobiles. Here, for example, the disc brake generates a braking force by pushing the piston together with the brake pad to the surface side of the disc by supplying hydraulic pressure from the outside into the caliper cylinder.

  Such disc brakes not only generate braking force based on hydraulic pressure when the vehicle is running, but also generate braking force based on the drive (rotation) of the electric motor when the vehicle is stopped or parked (parking). A hydraulic disc brake with an electric parking brake configured to operate as a brake is known (see, for example, Patent Document 1).

  The disc brake with an electric parking brake according to the prior art, when generating a braking force as a parking brake, propels the piston toward the disc by driving the electric motor. In this case, when the electric motor current reaches a preset target current value, the control device (controller) that controls the driving of the electric motor generates a target pressing force (target pressing force) for the piston. The determination is made and the driving of the electric motor is stopped.

  A disc brake with an electric parking brake provided on each of the left and right sides of the vehicle is configured to simultaneously drive the left and right electric motors (promotes the left and right pistons simultaneously) when generating a braking force as the parking brake. It has become.

JP 2012-81771 A

  By the way, when generating a braking force as a parking brake, electric power is supplied to the electric motor from a power source (battery) of the vehicle via a controller (control device). At this time, for example, when the voltage of the power source becomes lower than usual, the pressing force of the piston (the force with which the piston presses the brake pad) is the pressing force necessary for maintaining the parking (necessary pressing force). ) May be smaller.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a brake device that can obtain a necessary pressing force with both left and right pistons of a vehicle even with a low power supply voltage. is there.

  In order to solve the above-described problem, the present invention provides a piston holding mechanism that is provided with a piston propulsion mechanism for propelling a piston by an electric motor on each of the left and right sides of the vehicle, and holds the piston at a position propelled by the piston propulsion mechanism. And a control unit that controls driving of the electric motor based on a piston holding command.

A feature of the configuration adopted by the present invention is that the control means can vary the timing at which the piston reaches the position where the piston is held by the piston propulsion mechanism between the left and right piston propulsion mechanisms of the vehicle. From the reception of the piston holding command to the predetermined position, the left and right piston propulsion mechanisms of the vehicle simultaneously propel the pistons .

  According to the present invention, the required pressing force can be obtained with both the left and right pistons of the vehicle even with a low power supply voltage.

1 is a conceptual diagram of a vehicle equipped with a brake device according to an embodiment. It is a block diagram which shows the parking brake control apparatus in FIG. It is a longitudinal cross-sectional view which expands and shows the disc brake with an electric parking brake provided in the rear-wheel side in FIG. It is a characteristic diagram which shows an example of the relationship between the voltage input into a parking brake control apparatus, a target electric current value, and a stall electric current value. It is a flowchart which shows the control processing by the parking brake control apparatus in FIG. 1 when operating the parking brake by 1st Embodiment (apply). It is a flowchart which shows the application completion process in FIG. A characteristic diagram showing an example of the time change of the parking brake switch when the parking brake is activated, the thrust and current of the left rear wheel parking brake, the thrust and current of the right rear wheel parking brake, and the voltage input to the parking brake control device is there. It is a flowchart which shows the apply completion process by 2nd Embodiment. It is a flowchart following FIG. Parking brake switch when the parking brake is activated, left rear wheel parking brake thrust and current, right rear wheel parking brake thrust and current, left and right rear parking brake current sum, voltage input to the parking brake controller It is a characteristic diagram which shows an example of the time change of. It is a flowchart which shows the application completion process by 3rd Embodiment. A characteristic diagram showing an example of the time change of the parking brake switch when the parking brake is activated, the thrust and current of the left rear wheel parking brake, the thrust and current of the right rear wheel parking brake, and the voltage input to the parking brake control device is there. It is a flowchart which shows the control processing when operating the parking brake by 4th Embodiment. It is a flowchart which shows the LH apply completion process in FIG. It is a flowchart which shows the RH apply completion process in FIG. A characteristic diagram showing an example of the time change of the parking brake switch when the parking brake is activated, the thrust and current of the left rear wheel parking brake, the thrust and current of the right rear wheel parking brake, and the voltage input to the parking brake control device is there.

The present invention is an invention belonging to a group of inventions including a plurality of inventions described below. Hereinafter, the first to fourth embodiments will be described as embodiments of the invention group. The first to third embodiments correspond to the invention described in the scope of claims of the present applicant.
Hereinafter, a case where the brake device according to the embodiment of the present invention is mounted on a four-wheeled vehicle will be described as an example and described in detail with reference to the accompanying drawings.

  Here, FIG. 1 to FIG. 7 show a first embodiment of the present invention. In FIG. 1, for example, left and right front wheels 2 and left and right rear wheels 3 are provided on the lower side (road surface side) of a vehicle body 1 constituting a vehicle body. Each front wheel 2 and each rear wheel 3 is provided with a disk rotor 4 as a disk that rotates integrally therewith. That is, each front wheel 2 is sandwiched by each disk rotor 4 by a hydraulic disk brake 5, and each rear wheel 3 is sandwiched by each disk rotor 4 by a disk brake 31 with an electric parking brake described later. Thereby, a braking force is applied to each wheel (each front wheel 2 and each rear wheel 3).

  A brake pedal 6 is provided on the front board side of the vehicle body 1. The brake pedal 6 is depressed by the driver when the vehicle is braked. The brake pedal 6 is provided with a pedal switch 6A. The pedal switch 6A detects a depression operation of the brake pedal 6 and outputs a detection signal to the control unit 13 described later.

  The depression operation of the brake pedal 6 is transmitted to the master cylinder 8 via the booster 7. The booster 7 is composed of a negative pressure booster or the like provided between the brake pedal 6 and the master cylinder 8, and multiplies the pedaling force when the brake pedal 6 is depressed and transmits it to the master cylinder 8. At this time, the master cylinder 8 generates hydraulic pressure with the brake fluid supplied from the master reservoir 9. The master reservoir 9 constitutes a hydraulic fluid tank that contains brake fluid.

  The hydraulic pressure generated in the master cylinder 8 is sent to a hydraulic pressure supply device 11 (hereinafter referred to as ESC 11) via, for example, a pair of cylinder side hydraulic pipes 10A and 10B. The ESC 11 distributes and supplies the hydraulic pressure from the master cylinder 8 to the disc brakes 5 and 31 via the brake side piping portions 12A, 12B, 12C, and 12D. As a result, a braking force is applied to each wheel (each front wheel 2 and each rear wheel 3) as described above.

  The ESC 11 includes a hydraulic pressure supply controller 13 (hereinafter referred to as a control unit 13) that controls the operation of the ESC 11. The control unit 13 controls to increase, reduce or hold the brake fluid pressure supplied to the disc brakes 5, 31 from the brake side piping parts 12 </ b> A to 12 </ b> D by drivingly controlling the ESC 11. Thereby, for example, brake control such as boost control, braking force distribution control, brake assist control, anti-skid control, traction control, vehicle stabilization control including skid prevention, and slope start assist control is executed.

  The control unit 13 is configured by a microcomputer or the like, and power from the battery 14 is supplied through the power line 15. The control unit 13 is connected to a vehicle data bus 16 and the like as shown in FIG. In addition, you may use the ABS unit which is a well-known technique instead of ESC11. Furthermore, it is good also as a structure which does not provide ESC11 (it abbreviate | omits) and connects to the brake side piping parts 12A-12D directly from the master cylinder 8. FIG.

  The vehicle data bus 16 includes a CAN as a serial communication unit mounted on the vehicle body 1, and is connected to a large number of electronic devices mounted on the vehicle, the control unit 13, a parking brake control device 19 described later, and the like. It performs multiplex communication for in-vehicle use. In this case, as the vehicle driving information sent to the vehicle data bus 16, for example, information such as a detection signal from a steering angle sensor, an accelerator sensor, a brake sensor, a wheel speed sensor, and a tilt sensor (all not shown), And a detection signal (information) from the pressure sensor 17 or the like.

  The pressure sensor 17 is provided in each of the brake side pipe portions 12A, 12B, 12C, and 12D, and each caliper pressure (fluid pressure), that is, a later-described caliper 34 (cylinder portion 36) corresponding to the pipe internal pressure. ) Is detected individually. One or two pressure sensors 17 may be provided. For example, the pressure sensor 17 may be provided only in the cylinder side hydraulic pipes 10A and 10B between the master cylinder 8 and the ESC 11.

  The vehicle body 1 is provided with a parking brake switch 18 located in the vicinity of a driver's seat (not shown), and the parking brake switch 18 is operated by a driver. When the parking brake switch 18 is operated, a control signal is output (drive power is supplied) from the parking brake control device 19 described later to the disc brake 31 on the rear wheel 3 side (that is, an electric actuator 43 described later). The disc brake 31 on the rear wheel 3 side operates as a parking brake. Further, when releasing the operation as the parking brake, the parking brake switch 18 is operated to the braking release side, and a control signal for reversely rotating the electric actuator 43 to the disc brake 31 is output in accordance with this operation (drive power is supplied). Is done.

  The parking brake control device 19 is configured by a microcomputer or the like, and power from the battery 14 is supplied through the power line 15. The parking brake control device 19 constitutes a control means (controller, control unit) that is a constituent element of the present invention, and a disc brake 31 (described later) based on a signal (piston holding command) from the parking brake switch 18 or the like. That is, the driving of the electric actuator 43) is controlled to generate a braking force when the vehicle is parked or stopped. As shown in FIGS. 1 to 3, the parking brake control device 19 has an input side connected to the parking brake switch 18 and the like, and an output side connected to the electric actuator 43 and the like of the disc brake 31. The parking brake control device 19 is connected to the control unit 13 or the like of the ESC 11 via the vehicle data bus 16 on the input and output sides.

  The parking brake control device 19 has a storage unit (not shown) composed of, for example, a flash memory, a ROM, a RAM, etc. In this storage unit, the processing program shown in FIGS. A processing program used for control processing when operating (applying) is stored.

  The parking brake control device 19 drives an electric actuator 43 described later based on a signal (ON / OFF signal) output from the parking brake switch 18 when the driver of the vehicle operates the parking brake switch 18. The disc brake 31 is operated or released as a parking brake.

The parking brake control device 19 includes a voltage sensor unit 20 that detects a voltage VB from the power supply line 15, left and right motor drive circuits 21 and 21 that drive the left and right electric actuators 43 and 43, and left and right, respectively. The left and right current sensor units 22 and 22 for detecting the respective motor currents IM _L and IM _R of the electric actuator 43 are incorporated. In addition, instead of the left and right current sensor units 22 and 22, or together with the left and right current sensor units 22 and 22, between the motor drive circuits 21 and 21 from the power supply line 15, it may be provided with a current sensor 23 for detecting the sum of the motor current of the electric actuator 43 _(IM L + IM _R).

Thereby, when the parking brake control device 19 operates (applies) the parking brake, the voltage VB from the power line 15 (voltage VB input to the parking brake control device 19) and / or the left and right In accordance with the motor currents IM _L and IM _R of the electric actuator 43, the driving of one electric actuator 43 can be stopped and restarted in the middle thereof. That is, the parking brake control device 19 stops driving the one electric actuator 43 in the middle of the operation of the parking brake according to the voltage VB (and / or the motor current IM _L , IM _R ), and the other electric actuator 43. Then, after the piston 39 is propelled to a position where the required pressing force (required braking force) can be obtained, the driving of one electric actuator 43 is resumed, and the one electric actuator 43 causes the piston 39 to move to the required pressing force (required braking force). ) Can be propelled to a position where it can be obtained.

As a result, the parking brake control device 19 reaches a position where the piston 39 holds the piston 39 (holding position) by a piston propulsion mechanism (rotation linear motion conversion mechanism 40 , electric actuator 43), which will be described later, as necessary. The timing can be made different between the left and right piston propulsion mechanisms of the vehicle. In this case, the parking brake control device 19 receives the piston holding command (parking brake ON signal) from the parking brake switch 18 and then moves to a predetermined position with each piston 39 by the left and right piston propulsion mechanisms of the vehicle. It is configured to promote simultaneously. As described above, regarding the control for stopping and restarting the driving of one of the left and right electric actuators 43 in order to make the timing at which the left and right pistons 39 reach the holding position differ, Describe in detail.

  Next, the configuration of the disc brake 31 with an electric parking brake provided on the left and right rear wheels 3 will be described with reference to FIG. In FIG. 3, only one of the left and right disc brakes 31 provided corresponding to the left and right rear wheels 3 is shown.

  The disc brake 31 constituting the brake device of the present embodiment together with the parking brake control device 19 is configured as a hydraulic disc brake provided with an electric parking brake. The disc brake 31 includes a mounting member 32 attached to a non-rotating portion on the rear wheel 3 side of the vehicle, a brake pad 33 on the inner side and an outer side, and a caliper 34 provided with an electric actuator 43 described later. Has been.

  The mounting member 32 includes a pair of arm portions (not shown) that extend in the axial direction of the disk rotor 4 (that is, the disk axial direction) so as to straddle the outer periphery of the disk rotor 4, and are separated from each other in the disk circumferential direction. And a thick support portion 32 </ b> A that is fixed to a non-rotating portion of the vehicle at a position on the inner side of the disk rotor 4. The attachment member 32 is integrally formed with a reinforcing beam 32 </ b> B that connects the distal end sides of the respective arm portions to each other at a position on the outer side of the disk rotor 4.

  Thus, the arm portions of the mounting member 32 are integrally connected by the support portion 32A on the inner side of the disk rotor 4 and are integrally connected by the reinforcing beam 32B on the outer side. The inner and outer brake pads 33 are disposed on both surfaces of the disk rotor 4 and supported by the respective arm portions of the mounting member 32 so as to be movable in the disk axial direction. The inner and outer brake pads 33 are pressed against both sides of the disc rotor 4 by calipers 34 (caliper main body 35 and piston 39) described later.

  A caliper 34 is disposed on the mounting member 32 so as to straddle the outer peripheral side of the disk rotor 4. The caliper 34 includes a caliper main body 35 supported so as to be movable along the axial direction of the disc rotor 4 with respect to the respective arm portions of the mounting member 32, and a later-described piston 39 provided in the caliper main body 35. The rotation / linear motion conversion mechanism 40, the electric actuator 43, and the like are included.

  The caliper body 35 includes a cylinder part 36, a bridge part 37, and a claw part 38. The cylinder portion 36 is formed in a bottomed cylindrical shape in which one side in the axial direction is closed as a partition wall portion 36A and the other side facing the disk rotor 4 is an open end. The bridge portion 37 is formed to extend from the cylinder portion 36 in the disc axial direction so as to straddle the outer peripheral side of the disc rotor 4. The claw portion 38 is disposed so as to extend on the opposite side of the cylinder portion 36 with the bridge portion 37 interposed therebetween. The cylinder part 36 of the caliper main body 35 constitutes an inner leg part provided on one side (inner side) of the disk rotor 4, and the claw part 38 is an outer leg provided on the other side (outer side) of the disk rotor 4. Part.

  The cylinder portion 36 of the caliper main body 35 is supplied with hydraulic pressure accompanying the depression operation of the brake pedal 6 or the like via the brake side piping portion 12C or 12D shown in FIG. The cylinder portion 36 is integrally formed with a partition wall portion 36 </ b> A so as to be positioned between the cylinder portion 36 and an electric actuator 43 described later. An output shaft 43B of the electric actuator 43 is rotatably inserted on the inner peripheral side of the partition wall portion 36A. In the cylinder portion 36 of the caliper main body 35, a piston 39 and a rotation / linear motion converting mechanism 40 described later are provided. In this embodiment, the rotation / linear motion conversion mechanism 40 is configured to be accommodated in the piston 39. However, as long as the piston 39 is propelled by the rotation / linear motion conversion mechanism 40. The rotation / linear motion conversion mechanism 40 is not necessarily accommodated in the piston 39.

Here, one side of the piston 39 in the axial direction which is the opening side is inserted into the cylinder portion 36, and the other side in the axial direction facing the brake pad 33 on the inner side is closed as a lid portion 39A. Further, a rotation / linear motion conversion mechanism 40 is accommodated in the piston 39 inside the cylinder portion 36, and the piston 39 is propelled in the axial direction of the cylinder portion 36 by the rotation / linear motion conversion mechanism 40. It has become. The rotation / linear motion conversion mechanism 40 constitutes a piston propulsion mechanism, which is a constituent element of the present invention, together with an electric actuator 43 described later, and applies an external force (electric actuator 43) to the piston 39 separately from the addition of the hydraulic pressure into the cylinder portion 36. It is what is promoted by. Since the left and right disc brakes 31 are provided corresponding to the left and right rear wheels 3, respectively, the piston propulsion mechanism (rotational linear motion conversion mechanism 40 , electric actuator 43) is also provided on each of the left and right sides of the vehicle. Is provided.

  The rotation / linear motion conversion mechanism 40 includes a screw member 41 made of a rod-like body in which a male screw such as a trapezoidal screw is formed, and a linear motion member 42 serving as a propulsion member in which a female screw hole made of a trapezoidal screw is formed on the inner peripheral side. It is configured. That is, the screw member 41 screwed to the inner peripheral side of the linear motion member 42 constitutes a screw mechanism that converts a rotational motion by an electric actuator 43 described later into a linear motion of the linear motion member 42. In this case, the internal thread of the linear motion member 42 and the external thread of the screw member 41 are formed using a highly irreversible screw, in the present embodiment, a trapezoidal screw, thereby constituting a piston holding mechanism. This piston holding mechanism holds the linear motion member 42 (that is, the piston 39) with a frictional force (holding force) at an arbitrary position even when power supply to the electric actuator 43 is stopped, thereby saving energy. . The piston holding mechanism only needs to be able to hold the piston 39 at a position propelled by the piston propulsion mechanism (the rotation / linear motion conversion mechanism 40 and the electric actuator 43). For example, the piston holding mechanism may be a highly irreversible screw other than a trapezoidal screw. Good.

  The screw member 41 that is screwed to the inner peripheral side of the linear motion member 42 is provided with a flange portion 41A that is a large-diameter flange on one side in the axial direction, and the other side in the axial direction is a lid of the piston 39. It extends toward the portion 39A side. The screw member 41 is integrally connected to an output shaft 43B of an electric actuator 43 described later on the flange portion 41A side. Further, on the outer peripheral side of the linear motion member 42, an engagement protrusion 42A that stops the linear motion member 42 relative to the piston 39 (relative rotation is restricted) and allows relative movement in the axial direction is provided.

  An electric actuator 43 as an electric motor (parking brake actuator) is provided in the casing 43A. The casing 43A is fixed to the cylinder portion 36 of the caliper body 35 at a position outside the partition wall portion 36A. The electric actuator 43 includes a well-known motor incorporating a stator, a rotor, and the like, and a speed reducer (none of which is shown) that amplifies the torque of the motor. The speed reducer has an output shaft 43B that outputs the rotational torque after amplification. The output shaft 43B extends through the partition wall portion 36A of the cylinder portion 36 in the axial direction, and is connected to rotate integrally with the flange portion 41A side of the screw member 41 within the cylinder portion 36.

  The connecting means between the output shaft 43B and the screw member 41 can move, for example, in the axial direction, but is prevented from rotating in the rotational direction. For example, it can be fitted by spline fitting or polygonal column (non-circular) A known technique such as fitting) is used. As the speed reducer, for example, a planetary gear speed reducer or a worm gear speed reducer may be used. When a known speed reducer having no reverse operation (irreversible) such as a worm gear speed reducer is used, a reversible known mechanism such as a ball screw or a ball ramp mechanism is used as the rotation / linear motion conversion mechanism 40. You may combine.

  Here, when the driver operates the parking brake switch 18 shown in FIGS. 1 to 3, electric power is supplied from the parking brake control device 19 to the electric actuator 43 (motor thereof), and the output shaft 43 </ b> B of the electric actuator 43 is rotated. . For this reason, the screw member 41 of the rotation / linear motion conversion mechanism 40 is rotated integrally with the output shaft 43B in one direction, for example, and propels (drives) the piston 39 toward the disk rotor 4 via the linear motion member. Thereby, the disc brake 31 is operated (applied) as an electric parking brake by sandwiching the disc rotor 4 between the brake pads 33 on the inner side and the outer side.

  On the other hand, when the parking brake switch 18 is operated to the brake release side, the screw member 41 of the rotation / linear motion conversion mechanism 40 is driven to rotate in the other direction (reverse direction) by the electric actuator 43. As a result, the linear motion member 42 is driven in the retreating direction away from (separated from) the disk rotor 4 via the rotation / linear motion conversion mechanism 40, and the operation of the disk brake 31 is released (released).

  In this case, in the rotation / linear motion converting mechanism 40, when the screw member 41 is rotated relative to the linear motion member 42, the rotation of the linear motion member 42 in the piston 39 is restricted. Is relatively moved in the axial direction according to the rotation angle of the screw member 41. Thereby, the rotation / linear motion conversion mechanism 40 converts the rotational motion into a linear motion.

  A thrust bearing 44 is provided between the partition wall portion 36 </ b> A of the cylinder portion 36 and the flange portion 41 </ b> A of the screw member 41. The thrust bearing 44 receives the thrust load from the screw member 41 together with the partition wall portion 36A, and smoothes the rotation of the screw member 41 with respect to the partition wall portion 36A. In addition, a seal member 45 is provided between the partition wall portion 36A of the cylinder portion 36 and the output shaft 43B of the electric actuator 43. The seal member 45 causes the brake fluid in the cylinder portion 36 to leak to the electric actuator 43 side. It seals between the two so as to prevent it.

  A piston seal 46 as an elastic seal that seals between the cylinder portion 36 and the piston 39 and a dust boot 47 that prevents foreign matter from entering the cylinder portion 36 are provided on the opening end side of the cylinder portion 36. It has been. The dust boot 47 is configured by a flexible bellows-like seal member, and is attached between the opening end of the cylinder portion 36 and the outer periphery of the piston 39 on the lid portion 39A side.

  The disc brake 5 on the front wheel 2 side has substantially the same configuration except for the disc brake 31 on the rear wheel 3 side and the parking brake mechanism. That is, the disc brake 5 on the front wheel 2 side, like the disc brake 31 on the rear wheel 3 side, includes a rotation / linear motion conversion mechanism 40 (screw member 41 and linear motion member 42) that operates as a parking brake, an electric actuator 43, and the like. Not provided. However, in other respects, the disc brake 5 on the front wheel 2 side is configured in substantially the same manner as the disc brake 31. In some cases, a disc brake 31 with an electric parking brake may be provided on the front wheel 2 side instead of the disc brake 5.

  The brake device for a four-wheeled vehicle according to the present embodiment has the above-described configuration. Next, the operation thereof will be described.

  When the driver of the vehicle depresses the brake pedal 6, the pedaling force is transmitted to the master cylinder 8 via the booster 7, and brake fluid pressure is generated by the master cylinder 8. The hydraulic pressure generated in the master cylinder 8 is distributed and supplied to the disc brakes 5 and 31 via the cylinder side hydraulic pipes 10A and 10B, the ESC 11, and the brake side pipes 12A, 12B, 12C and 12D, and left and right. Braking force is applied to the front wheel 2 and the left and right rear wheels 3 respectively.

  In this case, the disc brake 31 on the rear wheel 3 side will be described. The hydraulic pressure is supplied into the cylinder portion 36 of the caliper 34 via the brake side piping portions 12C and 12D, and the piston 39 is increased according to the increase in the hydraulic pressure in the cylinder portion 36. Is slidingly displaced toward the brake pad 33 on the inner side. As a result, the piston 39 presses the inner brake pad 33 against one side surface of the disk rotor 4, and the entire caliper 34 is against the arms of the mounting member 32 by the reaction force at this time. Sliding displacement to the side.

  As a result, the outer leg portion (claw portion 38) of the caliper 34 operates to press the brake pad 33 on the outer side against the disc rotor 4, and the disc rotor 4 is moved from both sides in the axial direction by the pair of brake pads 33. The braking force according to the hydraulic pressure application is generated. On the other hand, when the brake operation is released, the hydraulic pressure supply into the cylinder part 36 is released and stopped, so that the piston 39 is displaced so as to move backward into the cylinder part 36, and the inner side and outer side brakes are released. As the pad 33 moves away from the disc rotor 4, the vehicle is returned to the non-braking state.

  Next, when the driver of the vehicle operates the parking brake switch 18 to activate (apply) the parking brake, power is supplied from the parking brake control device 19 to the electric actuator 43 of the disc brake 31 and the output of the electric actuator 43 is output. The shaft 43B is rotationally driven. The disc brake 31 with an electric parking brake converts the rotation of the electric actuator 43 into linear motion via the screw member 41 and the linear motion member 42 of the rotation / linear motion conversion mechanism 40, and moves the linear motion member 42 in the axial direction. By pushing the piston 39, the pair of brake pads 33 are pressed against both sides of the disc rotor 4.

  At this time, the linear motion member 42 is held in a braking state by a frictional force (holding force) generated between the screw member 41 and the disc brake 31 on the rear wheel 3 side is operated as a parking brake. That is, even after the power supply to the electric actuator 43 is stopped, the linear motion member 42 (that is, the piston 39) is held at the braking position by the piston holding mechanism including the female screw of the linear motion member 42 and the male screw of the screw member 41. be able to.

  On the other hand, when the driver operates the parking brake switch 18 to release the parking brake to release the parking brake, power is supplied from the parking brake control device 19 to the electric actuator 43 in the reverse direction of the motor, and the output shaft 43B of the electric actuator 43 is output. Is rotated in the opposite direction to that when the parking brake is activated. At this time, the rotation / linear motion conversion mechanism 40 releases the holding of the braking force by the screw member 41 and the linear motion member 42 and moves the linear motion member 42 to the cylinder portion with a movement amount corresponding to the reverse rotation of the electric actuator 43. 36 is moved in the return direction to release the braking force of the parking brake (disc brake 31).

  By the way, when generating a braking force as a parking brake, electric power is supplied to the electric actuator 43 from the battery 14 serving as a power source via the power supply line 15 and the parking brake control device 19. At this time, for example, when the voltage of the battery 14 becomes lower than usual, in the related art, the pressing force of the piston 39 (the force by which the piston 39 presses the brake pad 33) is a pressing force (a force necessary to maintain parking) ( The required pressing force may be smaller.

  That is, when generating a braking force as a parking brake, the piston 39 is propelled in the direction approaching the disk rotor 4 by driving the electric actuator 43. At this time, when the current of the electric actuator 43 reaches the target current value, the parking brake control device 19 determines that the piston 39 generates a target pressing force (target pressing force), and drives the electric actuator 43. Is configured to stop.

  Here, when the left and right electric actuators 43 of the vehicle are driven simultaneously, the total amount of current supplied to the left and right electric actuators 43 flows through the power supply line 15 at the same time, and a voltage drop in the power supply line 15 occurs. growing. In this case, for example, when the voltage of the battery 14 is lower than normal, the voltage VB input to the parking brake control device 19 is further reduced in combination with a voltage drop in the power supply line 15.

FIG. 4 shows the relationship between the target current value A1 corresponding to the target pressing force of the piston 39 and the maximum current value with respect to the input voltage VB, that is, the stall current value IM _{STL at} which the electric actuator 43 stops. . In FIG. 4, the voltage Vmin is a voltage at which the target current value A1 and the stall current value IM _STL are equal.

As indicated by a solid line 48 in FIG. 4, when the voltage VB is smaller than Vmin, the target current value A1 needs to be reduced according to the voltage VB at that time so as not to exceed the stall current value IM _STL. . For this reason, when the voltage VB becomes smaller than Vmin, the pressing force of the piston 39 may become smaller than the pressing force (necessary pressing force) necessary for maintaining the parking as the target current value A1 becomes smaller. .

  Here, for example, in order to reduce the voltage drop of the power supply line 15, it is conceivable to make the power supply line 15 thick and reduce the resistance value. However, in this case, there is a problem that the material cost and weight increase.

  Therefore, in the present embodiment, when braking by the electric actuator 43 (the parking brake is operated), it is possible to vary the timing at which the left and right disc actuators 31 stop the left and right electric actuators 43. It is said. More specifically, the parking brake control device 19 stops driving one of the electric actuators 43 according to the voltage input to the parking brake control device 19 while driving the left and right electric actuators 43. Then, when the current of the other electric actuator 43 reaches the target current value A1, the driving of the other electric actuator 43 is stopped, and then the driving of the one electric actuator 43 is resumed. When the current reaches the target current value A1, the driving of the one electric actuator 43 is stopped.

  Hereinafter, control processing performed by the parking brake control device 19 when the parking brake is operated (applied) will be described with reference to FIGS. 5 and 6. In the following description, the operation for applying the parking brake, that is, applying a predetermined pressing force to the brake pad 33 and maintaining the piston position at that time is referred to as “apply”. Further, the process of FIG. 5 is repeatedly executed at predetermined time intervals while the parking brake control device 19 is energized.

  When the processing operation of FIG. 5 starts, it is determined in step 1 whether there is an apply instruction (apply command, apply request) by the parking brake switch 18. If it is determined in step 1 that “NO”, that is, there is no apply instruction, the process returns to “START” via “END”. In this case, the process proceeds from “START” to step 1 after a predetermined time. On the other hand, if “YES” in step 1, that is, if it is determined that there is an apply instruction, the process proceeds to step 2.

  In step 2, based on the determination of “YES” in step 1, the parking brake control device 19 drives the electric actuator 43 in a direction (apply direction) in which the linear motion member 42 (piston 39) approaches the disk rotor 4. . In this case, the electric actuators 43 of both the left and right disc brakes 31 are driven. And it progresses to the following step 3. In the following description, for convenience, the motor of the electric actuator 43 located on the left rear wheel 3 (RL) side is the LH motor, and the motor of the electric actuator 43 located on the right rear wheel 3 (RR) side is the RH motor. That's it.

  In step 3, an apply completion process, that is, an apply completion process shown in FIG. In subsequent step 4, it is determined whether or not an LH completion flag, which will be described later, is ON. If “YES” is determined in step 4, that is, if the LH completion flag is determined to be ON, the process proceeds to step 5, the LH motor is stopped, and the process proceeds to subsequent step 6. On the other hand, if “NO” in step 4, that is, if it is determined that the LH completion flag is OFF, the process proceeds to step 6 without going through step 5.

  In step 6, it is determined whether an RH completion flag, which will be described later, is ON. If “YES” in step 6, that is, if it is determined that the RH completion flag is ON, the process proceeds to step 7, the RH motor is stopped, and the process proceeds to subsequent step 8. On the other hand, if it is determined “NO” in step 6, that is, if the RH completion flag is OFF, the process proceeds to step 8 without going through step 7.

  In step 8, it is determined whether the LH completion flag is ON and the RH completion flag is ON. If “YES” in step 8, that is, if it is determined that both the LH completion flag and the RH completion flag are ON, the process proceeds to step 9, and each timer (timer 1, timer 2) described later and each The flags (LH completion flag, RH completion flag) are cleared, that is, each timer is set to 0 and each flag is turned OFF, and the process returns to “START” via “END”. On the other hand, if “NO” in step 8, that is, it is determined that both the LH completion flag and the RH completion flag are not ON (at least one of the flags is OFF), the process returns to step 3.

Next, the apply completion processing in step 3 will be described with reference to FIG.
When the apply completion process starts, in step 11, the timer 1 is counted up. Next, in step 12, the predetermined time T1 has elapsed since the timer 1 started counting up, that is, since the electric actuator 43 has started to be driven (the energization of the LH motor and the RH motor has started). It is determined whether the timer 1 is equal to or longer than the predetermined time T1.

  If “NO” in step 12, that is, it is determined that the predetermined time T1 has not been reached (timer 1 <T1), the process proceeds to step 4 in FIG. 5 via “return” in FIG. On the other hand, if “YES” in step 12, that is, if it is determined that the predetermined time T1 has been reached (timer 1 ≧ T1), the process proceeds to step 13. Here, the predetermined time T1 is set to be longer than the time until the inrush current (see A0 in FIG. 7) generated immediately after energization of the LH motor and the RH motor becomes less than the predetermined value A1.

Next, in step 13, the current IM _{L of the} LH motor, the current IM _{R of the} RH motor, and the voltage VB input to the parking brake control device 19 are acquired. In this case, the current IM _{L of the} LH motor and the current IM _{R of the} RH motor are acquired (detected) by the current sensor units 22 and 22 of the parking brake control device 19, and the voltage VB is acquired (detected) by the voltage sensor unit 20. To do.

If the current IM _L , the current IM _R , and the voltage VB are acquired in step 13, a predetermined value A1 that is a target current value is set based on the characteristic line (solid line 48) in FIG. 4 in step 14. That is, the predetermined value A1 is set based on the voltage VB acquired in step 13. In FIG. 4, the predetermined value A1 is constant above Vmin, but the predetermined value A1 may be corrected according to the voltage VB (for example, the predetermined value A1 increases as the voltage VB increases). May be corrected). In FIG. 4, the predetermined value A1 and the stall current value IM _STL are the same at Vmin or less, but the predetermined value A1 may be smaller than the stall current value IM _STL , for example. Further, the predetermined value A1 may be corrected according to, for example, the inclination of the road surface to be parked or the hydraulic pressure P by the pressure sensor 17.

  In step 15, it is determined whether or not the voltage VB input to the parking brake control device 19 has continued below a predetermined value V1 (VB ≦ V1) for a predetermined time T2. If it is determined in step 15 that “NO”, that is, the voltage VB does not continue below the predetermined value V1 for the predetermined time T2, the process proceeds to step 21 described later. On the other hand, if “YES” in step 15, that is, if it is determined that the voltage VB has continued to be equal to or lower than the predetermined value V1 for the predetermined time T2, the process proceeds to step 16.

  Here, the predetermined value V1 is set as a threshold value of a voltage value at which any one of the electric actuators 43 should be stopped. This threshold value (predetermined value V1) is determined in advance by, for example, experimentation or calculation in consideration of the voltage (power supply voltage) of the battery 14, the amount of voltage drop when the left and right electric actuators 43 are being driven simultaneously, and the like. I ask for it. Further, the position of the piston 39 when the voltage VB reaches the predetermined value V1 corresponds to a position (predetermined position) where the left and right pistons 39 are simultaneously propelled after receiving the piston holding command (parking brake ON signal). .

In the present embodiment, as shown in FIG. 4, the predetermined value V1 is larger than Vmin. For example, the predetermined value V1 may be the same as Vmin (V1 = Vmin). Further, when the predetermined value A1 is corrected so as to become smaller in accordance with, for example, the slope of the road surface to be parked or the hydraulic pressure P by the pressure sensor 17 in step 14, the stall current value IM _STL and the predetermined value A1 are obtained. Since the intersecting voltage Vmin is also reduced, the predetermined value V1 may be corrected accordingly.

  In step 16, it is determined whether either the LH completion flag or the RH completion flag is ON. When it is determined in step 16 that “NO”, that is, both the LH completion flag and the RH completion flag are OFF (both the LH motor and the RH motor are being driven), the process proceeds to step 25, where the RH motor To stop. Then, in the following step 26, a timer 2 flag for operating the timer 2 described later is turned on, and the process proceeds to step 21. On the other hand, in step 16, it is determined that “YES”, that is, either the LH completion flag or the RH completion flag is ON (either one of the LH motor and the RH motor is stopped due to the completion of the application). If yes, go to Step 17.

  In step 17, it is determined whether or not the timer 2 flag is ON. If “NO” in step 17, that is, if it is determined that the timer 2 flag is OFF, the process proceeds to step 21. On the other hand, if “YES” in step 17, that is, if it is determined that the timer 2 flag is ON, the process proceeds to step 18, where the stopped RH motor is re-driven (driving is resumed), and subsequent step 19. The timer 2 is counted up. In step 20, after the timer 2 starts counting up, that is, after the RH motor is driven (starting energization), whether the predetermined time T4 has passed (the timer 2 is equal to or longer than the predetermined time T4). It is determined whether or not.

  If “NO” in step 20, that is, if it is determined that the predetermined time T4 has not been reached (timer 2 <T4), the process proceeds to step 4 in FIG. 5 via “return” in FIG. On the other hand, if “YES” in step 20, that is, if it is determined that the predetermined time T4 has been reached (timer 2 ≧ T4), the process proceeds to step 21. Here, the predetermined time T4 is set to be longer than the time until the inrush current (see A2 in FIG. 7) generated immediately after energization of the RH motor becomes less than the predetermined value A1.

In step 21, it is determined whether or not the current I _{M L of the} LH motor has continued for a predetermined time A3 or more (IM _L ≧ A1) for a predetermined time T3. If “YES” in step 21, that is, if it is determined that the current IM _L has continued to be greater than or equal to the predetermined value A1 for the predetermined time T3, the LH completion flag is turned ON in the subsequent step 22 and then the process proceeds to step 23. move on. On the other hand, in step 21, "NO", i.e., between the current IM _L is a predetermined time T3, when it is determined not to continue more than a predetermined value A1, without passing through the step 22, the process proceeds to step 23.

In step 23, the current IM _R of RH motor, for a predetermined time T5, or the predetermined value A1 whether to continue (IM _R ≧ A1) determines. In step 23, "YES", i.e., between the current IM _R is a predetermined time T5, if it is determined that the continued more than a predetermined value A1, after ON the RH completion flag in the subsequent step 24, in FIG. 6 Go to step 4 in FIG. 5 via “return”. On the other hand, in step 23, "NO", i.e., between the current IM _R is a predetermined time T5, if it is determined not to continue more than a predetermined value A1, without passing through the step 24, "return 6 The process proceeds to step 4 in FIG. 5 via the “return”.

Next, when the parking brake control device 19 performs the processing of FIGS. 5 and 6, the operation of the parking brake switch 18 (SW), the thrust (F) generated by the rotation / linear motion conversion mechanism 40 on the left rear wheel 3 side, _L) and the current of the electric actuator 43 (LH motor) _(IM L), the thrust generated by the rotation-linear motion conversion mechanism 40 of the right rear wheel 3 side _{(F R)} and the current of the electric actuator 43 (RH motor) (IM _R ), The time change of the voltage VB input to the parking brake control device 19 will be described with reference to FIG.

At the time point a1, the parking brake switch 18 does not give an apply instruction (APL), the left and right electric actuators 43, 43 are stopped, and the electric actuators 43, 43 (LH motor and RH The motor currents IM _L and IM _R become zero. When an apply instruction is given by the parking brake switch 18 at time a2 on the time axis (determined as “YES” in step 1), the parking brake control device 19 causes the left and right electric actuators 43, 43 (LH linear member 42 motor and RH motor) (piston 3 9) is started in a direction approaching the disc rotor 4 (energized) (step 2). At this time (immediately after energization), since the LH motor and the RH motor shift from the stopped state to the driven state, a large inrush current (A0) is generated once and then decreases and becomes constant. In order to avoid the erroneous determination due to the inrush current, the determination using the current IM _L , the current IM _R , and the voltage VB is not performed during the predetermined time T1 from the time point a2 to the time point a3 (step 12).

After the elapse of the predetermined time T1, when the thrust F generated by the rotation / linear motion conversion mechanism 40 is increased by driving the LH motor and the RH motor and the brake pad 33 is pressed against the disc rotor 4, a4 from the time point a3 on the time axis. Between the time points, the currents IM _L and IM _R of the LH motor and the RH motor gradually increase. Accordingly, the voltage drop in the power supply line 15 increases, and the voltage VB input to the parking brake control device 19 gradually decreases. Then, it is determined whether or not the voltage VB has continued below the predetermined value V1 for the predetermined time T2 (step 15). When the voltage VB continues to be below the predetermined value V1 for the predetermined time T2, the time axis At step a5, power supply to the RH motor is temporarily stopped (step 25).

On the other hand, energization of the LH motor continues, the current IM _L of the LH motor for a predetermined time T3, whether to continue more than a predetermined value A1 is determined (step 21). Current IM _L becomes greater than a predetermined value A1 in a6 point on the time axis, when at a7 point of the time axis reaches a predetermined time T3, the energization of the LH motor with said a7 time is stopped, the left rear wheel 3 (RL) side The electric actuator 43 is applied (step 5). Thereby, it determines with "YES" in both step 16 and step 17, and electricity supply to an RH motor is started (step 18).

When energization to the RH motor is started at time a8 on the time axis, the RH motor shifts from the stopped state to the driven state, and therefore a large inrush current (see A2 in FIG. 7) occurs once and then decreases. To do. To avoid erroneous determination due to the rush current, during a predetermined time T4, from a8 point of the time axis to a9 time, it does not perform the determination using the current IM _R (step 20).

After a predetermined time T4, the current IM _R of RH motor for a predetermined time T5, whether to continue more than a predetermined value A1 is determined (step 23). Current IM _R becomes higher than a predetermined value A1 at a10 times in the time axis, reaches the predetermined time T5 at a11 times in the time axis, the energization of the RH motor with said a11 time is stopped, right rear wheel 3 (RR) side The electric actuator 43 is also applied (step 7). As a result, "YES" is determined in step 8, and in step 9, each timer (timer 1, timer 2) and each flag (LH completion flag, RH completion flag) are cleared, and the left and right disc brakes of the vehicle are cleared. 31 apply is completed.

  As described above, according to the first embodiment, when the voltage VB falls below the predetermined value V1 except for the decrease in the voltage VB due to the inrush current, the one electric actuator 43 is stopped to The voltage drop of the line 15 can be reduced, and the necessary pressing force of the piston 39 (the pressing force necessary for maintaining parking) can be ensured with a lower power supply voltage. Further, since the left and right electric actuators 43 and 43 are simultaneously driven until the voltage VB falls below the predetermined value V1 (in a region where the current is small except for the inrush current), the time until the parking brake operation is completed is long. Can be avoided.

  Note that if either one of the left and right electric actuators 43 has been applied when the voltage VB falls below the predetermined value V1, step 16 (determination of which one has completed applying) is performed. Even if “YES” is determined, “NO” is determined in the step 17 (determination of whether or not the timer 2 flag is ON), and the process proceeds to the step 21. Therefore, as a result, the drive of the electric actuator 43 that has not been applied is continued as it is. If the voltage VB is sufficiently large, the left and right electric actuators 43 can be driven simultaneously until the application is completed.

In the first embodiment, the electric actuator 43 (RH motor) on the right side of the vehicle is stopped when the voltage VB falls below the predetermined value V1, but the electric actuator 43 (LH) on the left side of the vehicle is used. The motor may be configured to stop. Further, at the time that the voltage VB falls below a predetermined value V1, compares the current IM _R of the current IM _L and RH motor LH motor, be determined whether to stop the one of the motor in accordance with the current value Good.

Next, FIGS. 8 to 10 show a second embodiment of the present invention. In the first embodiment described above, a configuration for determining whether or not to stop one of the electric actuators 43 on the way using the voltage VB input to the parking brake control device 19, that is, a threshold for the determination. The voltage VB is used. On the other hand, in the present embodiment, it is determined whether or not one electric actuator 43 is stopped halfway using the currents IM _L and IM _R of the electric actuator 43, that is, as a threshold for the determination. The current IM _L and IM _R are used. Note that the description of the present embodiment will focus on portions that are different from the first embodiment described above.

  The apply completion process shown in FIGS. 8 and 9 is used in this embodiment instead of the apply completion process shown in FIG. 6 of the first embodiment described above. The steps before and after the apply completion processing of this embodiment, that is, the processing of FIG. 5 are as described in the first embodiment.

In this embodiment, it monitors the current IM _L of the electric actuator 43 of the left rear wheel 3 side (LH motor), the current IM _R of the electric actuator 43 of the right rear wheel 3 side (RH motor) (Detection), either A configuration in which the other motor is temporarily stopped when the currents IM _L and IM _R of one of the motors continue to exceed a predetermined value A3 (IM _L ≧ A3 or IM _R ≧ A3) for a predetermined time T2. It is said.

Namely, the a3 point of the time axis of the characteristic diagram of FIG. 10, between the current IM _L of LH motor for a predetermined time T2, more than a predetermined value A3 (IM _L ≧ A3) determines whether to continue (Step 35 ) starts the current IM _R of RH motor starts for a predetermined time T2, more than a predetermined value A3 (IM _R ≧ A3) determines whether to continue (step 39), either one of the motor When it is determined “YES” with respect to the other motor, the other motor is stopped (step 37, step 41).

The predetermined value A3 is set in step 34. That is, based on the voltage VB acquired in step 33, the predetermined value A3 is set together with the predetermined value A1. Specifically, the predetermined value A3 is set as a threshold value of a current value at which one of the electric actuators 43 should be stopped according to the voltage VB at that time (when applying). In this case, for example, the smaller the voltage VB, the smaller the predetermined value A3 can be set. The relationship between the threshold value (predetermined value A3) and the voltage VB takes into account the voltage (power supply voltage) of the battery 14, the voltage drop when the left and right electric actuators 43 are driven simultaneously, and the like. Obtained in advance by experiments, calculations, etc. The position of the piston 39 when the currents IM _L and IM _R reach the predetermined value A3 is a position (predetermined position) for simultaneously propelling the left and right pistons 39 after receiving the piston holding command (parking brake ON signal). ).

The characteristic diagram of FIG. 10, in a4 time of the time axis, the current IM _L of LH motor becomes a predetermined value or more A3, in a5 point of the time axis, it reaches a predetermined time T2, "YES" in step 35 And the RH motor is stopped at time a5 on the time axis (step 37). At this time, since the RH pause flag is turned ON (step 38), "NO" is continued in the subsequent step 40. For this reason, when the RH motor is stopped, the process does not proceed to step 41 and the LH motor is stopped. In the case of reverse, that is, current IM _R of RH motor becomes a predetermined value or more A3, upon reaching a previously predetermined time T2 is, LH motor is stopped (step 41), LH pause flag is turned ON Therefore (step 42), "NO" is continued in the subsequent step 36. For this reason, when the LH motor is stopped, the routine does not proceed to step 37 and the RH motor is not stopped.

  Subsequently, when the applied electric actuator 43 is completely applied in step 48 (and step 49, step 4 and step 5) or in step 50 (and step 51, step 6 and step 7), In step 43, “YES” is determined. As a result, the driving of the electric actuator 43 that has been stopped in step 45 or step 53 is resumed.

  In the characteristic diagram of FIG. 10, at the time point a7 on the time axis, the power supply to the LH motor is stopped by the processing of step 48 (and step 49, step 4 and step 5), and the left rear wheel 3 (RL) side is stopped. The electric actuator 43 is applied. Thereafter, energization to the RH motor is resumed at time point a8 (step 53).

Then, in order to avoid erroneous determination due to the inrush current (see A2 in FIG. 10), from a8 time of the time axis until the predetermined time T4 has elapsed, not performed the determination of the current IM _R (in step 47 is "NO" Judgment). After a predetermined time T4, the current IM _R of RH motor for a predetermined time T5, whether to continue more than a predetermined value A1 is determined (step 50). Thereafter, current IM _R becomes higher than a predetermined value A1 at a10 times in the time axis, reaches the predetermined time T5 at a11 times in the time axis, the energization of the RH motor with said a11 time is stopped, right rear wheel 3 (RR ) Side electric actuator 43 is also applied (step 7).

Thus, also in the second embodiment configured as described above, it is possible to obtain substantially the same operational effects as those of the first embodiment described above. That is, in the case of the present embodiment, when the current (IM _L orIM _R ) of one electric actuator 43 becomes equal to or greater than the predetermined value A3, the voltage drop of the power supply line 15 is reduced by stopping the other electric actuator 43. In addition, the necessary pressing force of the piston 39 can be ensured with a lower power supply voltage.

In the second embodiment, the one electric actuator 43 previously established is driven as it is under the condition that the currents IM _L and IM _R continue for a predetermined time T2 at a predetermined value A3 or more. The other electric actuator 43 is configured to be temporarily stopped, but may be reversed. That is, a configuration may be adopted in which one electric actuator 43 established earlier is temporarily stopped and the other electric actuator 43 is driven as it is.

Further, in the second embodiment, the current sensor units 22 and 22 are used to determine whether to temporarily stop any one of the electric actuators 43 using the currents IM _L and IM _R of the left and right electric actuators 43. It was. However, the total current IM _L + IM _R of the left and right electric actuators 43 by the current sensor unit 23 may be used without using the current sensor units 22 and 22.

In this case, monitoring the total current _IM L + IM _R from a3 point of the time axis, while the total current _IM L + IM _R is a predetermined time T2, when continuing more than a predetermined value A4, the one of the electric actuator 43 It can be set as the structure which pauses. Then, when the total current IM _L + IM _R continues for a predetermined time T3 or the predetermined time T5 for a predetermined value A5 or more corresponding to the target pressing force, it can be configured to determine that the application is completed. In this case, if the current sensor unit 23 is provided, the current sensor units 22 and 22 are not necessary, and the number of sensors can be reduced from two to one.

The predetermined value A4 is set as a threshold value of the total current value at which any one of the electric actuators 43 should be stopped according to the voltage VB at that time (when applying). In this case, for example, the smaller the voltage VB, the smaller the predetermined value A4 can be set. Such a threshold value (predetermined value A4) is preliminarily determined by, for example, experiments or calculations in consideration of the voltage (power supply voltage) of the battery 14 and the voltage drop when the left and right electric actuators 43 are driven simultaneously. I ask for it. The position of the piston 39 when the total current IM _L + IM _R reaches the predetermined value A4 is a position (predetermined position) for simultaneously propelling the left and right pistons 39 after receiving the piston holding command (parking brake ON signal). ).

  Further, the predetermined value A3 (or the predetermined value A4) as the threshold is set so that the voltage VB does not fall below Vmin. For this reason, the predetermined value A3 (or the predetermined value A4) may be corrected according to the voltage VB. For example, when the voltage VB is sufficiently large, a predetermined value A3 (or a predetermined value A4) that is a current threshold value for determining whether to stop one motor is used as a predetermined value A1 that is a current threshold value for determining whether or not the target pressing force is reached. (Or the predetermined value A5), that is, by correcting the predetermined value A3> the predetermined value A1 (or the predetermined value A4> the predetermined value A5), the left and right electric actuators 43 are completely applied. Can be driven simultaneously.

  Next, FIG. 11 and FIG. 12 show a third embodiment of the present invention. A feature of the present embodiment is that the determination whether or not to stop one of the electric actuators 43 is performed using the elapsed time after receiving the piston holding command (parking brake ON signal), that is, In the configuration, the elapsed time is used as a threshold for determination. Note that the description of the present embodiment will focus on portions that are different from the first embodiment described above.

  The apply completion process shown in FIG. 11 is used in this embodiment instead of the apply completion process shown in FIG. 6 of the first embodiment described above. The steps before and after the apply completion processing of this embodiment, that is, the processing of FIG. 5 are as described in the first embodiment.

  In the present embodiment, a process after receiving an apply command (parking brake ON signal) from the parking brake switch 18 and driving the electric actuators 43 of both the left and right disc brakes 31 (starting energization of the LH motor and the RH motor). When the time (timer 1) reaches a predetermined time T6, the driving of one of the electric actuators 43 is temporarily stopped. That is, the timer 1 starts counting up at time a2 on the time axis of the characteristic diagram of FIG. 12 (step 61), and when it is determined that the predetermined time T6 has been reached at time a5 on the time axis (step 62), RH The configuration is such that energization of the motor is stopped (step 66).

  The predetermined time T6 is set as a threshold value for a time (elapsed time after receiving the apply command) when one of the electric actuators 43 should be stopped. Such a threshold (predetermined time T6) is preliminarily determined by, for example, experiments or calculations in consideration of the voltage of the battery 14 (power supply voltage), the voltage drop when the left and right electric actuators 43 are simultaneously driven, and the like. I ask for it. The position of the piston 39 when the elapsed time (timer 1) reaches the predetermined time T6 is the position (predetermined position) for simultaneously propelling the left and right pistons 39 after receiving the piston holding command (parking brake ON signal). ).

In a5 point of the time axis, if the conduction is stopped to RH motor, determination current IM _L of LH motor, for a predetermined time T3, of whether to continue more than a predetermined value A1 (IM _L ≧ A1) (Step 67). The current IM _L becomes greater than a predetermined value A1 in a6 point on the time axis, reaches the predetermined time T3 at a7 point of the time axis, the energization of the LH motor with said a7 time is stopped, the left rear wheel 3 (RL ) Side electric actuator 43 is applied (step 5). As a result, “YES” is determined in step 65, and energization of the RH motor is started at time a8 on the time axis (step 69).

Then, in order to avoid erroneous determination due to the inrush current (see A2 in FIG. 12), from a8 time of the time axis until the predetermined time T4 has elapsed, not performed the determination of the current IM _R (in step 71 is "NO" Judgment). After a predetermined time T4, the current IM _R of RH motor for a predetermined time T5, whether to continue more than a predetermined value A1 is determined (step 72). Thereafter, current IM _R becomes higher than a predetermined value A1 at a10 times in the time axis, reaches the predetermined time T5 at a11 times in the time axis, the energization of the RH motor with said a11 time is stopped, right rear wheel 3 (RR ) Side electric actuator 43 is also applied (step 7).

In the third embodiment, when the timer 1 reaches the predetermined time T6, the electric actuator 53 (RH motor) on the right side of the vehicle is stopped. However, the electric actuator 53 (LH motor) on the left side of the vehicle is used. It is good also as a structure which stops. Further, at the time the timer 1 has reached the predetermined time T6, it is compared with the current IM _R of the current IM _L and RH motor LH motor, be determined whether to stop the one of the motor in accordance with the current value Good.

In the third embodiment, the predetermined time T6 is constant, but the predetermined time T6 is corrected according to the voltage VB at that time (when applying), the current IM _{L of the} LH motor, and the current IM _{R of the} RH motor. May be.

  Thus, also in the third embodiment configured as described above, it is possible to obtain substantially the same operational effects as those of the first embodiment described above. That is, in the case of the present embodiment, when the timer 1 reaches the predetermined time T6, one of the electric actuators 33 is stopped to reduce the voltage drop of the power supply line 15, and the piston 39 of the piston 39 can be reduced with a lower power supply voltage. Necessary pressing force can be secured.

  Next, FIGS. 13 to 16 show a fourth embodiment of the present invention. The feature of this embodiment is that when a piston holding command is received, one electric actuator is driven to propel one piston, and after a predetermined time has elapsed, the other piston is driven to drive the other piston. It is in the configuration to be made. Note that the description of the present embodiment will focus on portions that are different from the first embodiment described above.

  The processing shown in FIGS. 13 to 15 is used in this embodiment instead of the processing shown in FIGS. 5 and 6 of the first embodiment described above.

  In the present embodiment, when an apply command is received from the parking brake switch 18, the electric actuator 43 of one of the left and right disc brakes 31, 31 is driven (energization of the LH motor or RH motor is started). The electric actuator 43 of the other disk brake 31 is driven (energization of the RH motor or LH motor is started) after a predetermined time T7 has elapsed. That is, when an Apply command is received at time point a2 in the characteristic diagram of FIG. 16 (when it is determined “YES” in Step 101), energization to the LH motor is started (Step 102), and this energization start is started. When the elapsed time from (timer 3) reaches a predetermined time T7, energization of the RH motor is started (step 108).

  The predetermined time T7 is set as a threshold value for the drive start time of the electric actuator 43 to be driven later (elapsed time after receiving the apply command). Such a threshold value (predetermined time T7) is determined in advance by, for example, experiments or calculations in consideration of the voltage of the battery 14 (power supply voltage), the voltage drop when the left and right electric actuators 43 are simultaneously driven, and the like. I ask for it. For example, during the predetermined time T7, the current of the other (actuated later) electric actuator 43 is small (the pressing force is generated) at the time a7 of the time axis when one (actuated earlier) electric actuator 43 completes the application. In such a state that the pressing force is sufficiently small). The predetermined time T7 may be constant, but the predetermined time T7 may be corrected according to the magnitude of the voltage VB. For example, if the voltage VB is sufficiently large, the left and right electric actuators 43 can be driven simultaneously by correcting the predetermined time T7 to 0 (T7 = 0).

  Thus, also in the fourth embodiment configured as described above, it is possible to obtain substantially the same operational effects as those of the first embodiment described above. That is, in the present embodiment, one piston 39 is propelled by driving one electric actuator 43, and the other piston 39 is propelled by driving the other electric actuator 43 after a predetermined time T7 has elapsed. The configuration is to let Thereby, the voltage drop of the power supply line 15 can be reduced, and the required pressing force of the piston 39 can be ensured with a lower power supply voltage.

  In each of the above-described embodiments, the case where the left and right rear wheel side brakes are disc brakes 31 with an electric parking brake has been described as an example. However, the present invention is not limited to this. For example, the brakes of all four wheels may be constituted by disc brakes with an electric parking brake.

  Moreover, in each embodiment mentioned above, it demonstrated exemplifying the hydraulic disc brake 31 with an electric parking brake. However, the present invention is not limited to this. For example, an electric disc brake that does not require supply of hydraulic pressure may be used. Further, the present invention is not limited to the disc brake type brake device, and may be configured as, for example, a drum brake type brake device.

  According to the above embodiment, the required pressing force can be obtained with both the left and right pistons of the vehicle even with a low power supply voltage.

  In other words, according to the embodiment, the control means can vary the timing at which the piston reaches the position where the piston is held by the piston propulsion mechanism between the left and right piston propulsion mechanisms of the vehicle. That is, by stopping the piston of one of the left and right piston propulsion mechanisms, the piston of the other propulsion mechanism can be made to precede the piston of one propulsion mechanism. In this case, the electric motor that propels the piston of the other propulsion mechanism is driven, and the electric motor that propels the piston of the one propulsion mechanism is stopped. As a result, the timing of the voltage drop accompanying the driving of the electric motor and the timing of the increase of the electric motor current necessary for obtaining the required pressing force are determined according to the electric motor of one propulsion mechanism and the electric motor of the other propulsion mechanism. And can be shifted. As a result, the required pressing force can be obtained with both the left and right pistons of the vehicle even with a low power supply voltage.

  According to the embodiment, the control means is configured to simultaneously propel the respective pistons by the left and right piston propulsion mechanisms from the reception of the piston holding command to the predetermined position. Thereby, it is possible to suppress an excessive increase in the time until both pistons reach the holding position while varying the timing at which the left and right pistons reach the holding position.

  According to the embodiment, the predetermined position corresponding to the position where the piston is simultaneously driven is set as the position where the voltage input to the control means reaches the predetermined threshold. Thereby, the drive of the electric motor of one propulsion mechanism can be stopped according to the voltage input to the control means.

  According to the embodiment, the predetermined position corresponding to the position where the pistons are simultaneously driven is set as a position where the current values of the left and right electric motors reach a predetermined threshold value. Thereby, the drive of the electric motor of one propulsion mechanism can be stopped according to the current value of the left and right electric motors.

  According to the embodiment, the predetermined position corresponding to the position where the piston is simultaneously driven is set as a position where the elapsed time after receiving the piston holding command reaches the predetermined threshold. Thereby, the drive of the electric motor of one propulsion mechanism can be stopped according to elapsed time.

  According to the embodiment, when receiving the piston holding command, the control means propels one of the left and right piston propulsion mechanisms of the vehicle, and before the one piston reaches a position for holding the piston. The other piston of the left and right piston propulsion mechanisms of the vehicle is propelled. Thereby, it is possible to suppress an excessive increase in the time until both pistons reach the holding position while varying the timing at which the left and right pistons reach the holding position.

19 Parking brake control device (control means)
39 Piston 40 Rotational linear motion conversion mechanism (piston propulsion mechanism, piston holding mechanism)
43 Electric actuator (electric motor)

Claims (4)

A piston propulsion mechanism for propelling the piston by an electric motor is provided on each of the left and right sides of the vehicle,
A piston holding mechanism for holding the piston in a position propelled by the piston propulsion mechanism;
In a brake device having a control means for controlling the driving of the electric motor based on a piston holding command,
The control means includes
The timing at which the piston reaches the position where the piston is held by the piston propulsion mechanism can be made different between the left and right piston propulsion mechanisms of the vehicle. A brake device , wherein each piston is propelled simultaneously by left and right piston propulsion mechanisms . The brake device according to claim 1 , wherein the predetermined position is set as a position where a voltage input to the control means reaches a predetermined threshold value. 2. The brake according to claim 1 , wherein the predetermined position is set as a position where the current values of the left and right electric motors reach a predetermined threshold set in accordance with a voltage input to the control means. apparatus. 2. The brake device according to claim 1 , wherein the predetermined position is set as a position at which an elapsed time after receiving the piston holding command reaches a predetermined threshold value.

Images