WO2019111397A1 - Control method and control device for vehicle - Google Patents

Abstract

A control method for a vehicle comprising a drive source for traveling, an automatic transmission connected to the drive source and having a linking element for forward motion, and a negative pressure booster for assisting the driver's brake pedal pressure wherein when a predefined condition for stopping the drive source is satisfied during travel, sailing stop control is executed to stop the drive source and release the linking element for forward motion. Furthermore, while the sailing stop control is being executed, a brake device that generates braking force without the use of the negative pressure booster or manipulation by the driver is operated, thereby preventing any acceleration that is contrary to the driver's intention.

Description

Control method and control device for vehicle

The present invention controls a vehicle that performs sailing stop control that stops the drive source and releases the fastening element between the drive source and the drive wheel when a preset drive source stop condition is satisfied during traveling. About.

As a measure for improving the fuel consumption performance of the vehicle, so-called sailing stop control is known, in which the driving source (internal combustion engine) is stopped and the vehicle travels by inertia when a predetermined condition is satisfied during traveling. In JP2012-47148A, sailing stop control is started when the vehicle speed is equal to or higher than a preset lower limit speed, and the purpose is to improve fuel consumption.

However, during sailing stop control, so-called engine braking does not work, so when entering a downhill road, the vehicle may accelerate due to gravity. When the driver depresses the brake pedal to suppress acceleration, the sailing stop control is released. That is, in the control of the above document, since the sailing stop control is canceled on the down slope road suitable for traveling with inertia, the fuel efficiency improvement effect by the sailing stop control is reduced.

So, in this invention, it aims at enlarging the fuel-consumption improvement effect by sailing stop control more.

According to an aspect of the present invention, when the drive source stop condition set in advance is satisfied during traveling, sailing stop control is performed to stop the drive source and release the forward fastening element. Furthermore, during sailing stop control, acceleration that is against the driver's intention is suppressed by operating the brake device that generates the braking force without using a negative pressure type booster and without the driver's operation. Do.

FIG. 1 is a system configuration diagram of a vehicle. FIG. 2 is a block diagram of a braking system. FIG. 3 is a flowchart of a control routine executed by the controller. FIG. 4 is a timing chart when the control routine of FIG. 3 is executed. FIG. 5 is a timing chart as a comparative example.

Hereinafter, embodiments of the present invention will be described with reference to the attached drawings.

FIG. 1 is a system configuration diagram of a vehicle according to the present embodiment. The vehicle includes an engine 1 as a drive source, an automatic transmission 2, a motor generator (hereinafter also referred to as MG) 4, a battery 5, a final gear device 6, a drive wheel 7, and a controller 9. It consists of

In addition, the vehicle is equipped with a Vehicle Dynamics Control system (hereinafter also referred to as a VDC system) that performs vehicle behavior control such as side slip prevention and stable turning etc., and a brake fluid pressure unit (hereinafter also referred to as a VDC unit) used for vehicle behavior control. Say) 10).

The engine 1 is an internal combustion engine fueled by gasoline or light oil, and its rotational speed, torque, and the like are controlled based on a command from the controller 9.

The automatic transmission 2 is a continuously variable transmission in this embodiment, and includes a clutch 3 as a forward engagement element. The clutch 3 is disposed between the transmission mechanism of the continuously variable transmission and the engine 1. When the clutch 3 is engaged, the rotational torque of the engine 1 is transmitted to the drive wheel 7 via the automatic transmission 2, the propeller shaft 11, the final gear device 6 and the drive shaft 12. The shift control and the engagement and release control of the forward coupling element are performed by the controller 9.

The MG 4 is a synchronous electric rotating machine connected to the output shaft of the engine 1 via a transmission mechanism (not shown) consisting of a belt and a pulley. When the MG 4 receives rotational energy from the engine 1, the MG 4 functions as a generator, and the generated power is charged to the battery 5. The MG 4 can also function as a generator when the engine 1 is rotated by the drive wheels 7. That is, the MG 4 can regenerate the kinetic energy of the vehicle as electric power. The MG 4 can be driven by the power of the battery 5 and the torque assist of the engine 1 can be performed by the torque of the MG 4.

The controller 9 receives information (navigation information) acquired by an on-vehicle navigation system, information outside the vehicle acquired by inter-vehicle communication or road-vehicle communication via a network, information from an on-vehicle camera and a detection signal of an acceleration sensor. Ru. In addition to the above, signals from a crank angle sensor that detects an engine rotational speed, an accelerator opening degree sensor, a brake sensor that detects a brake depression amount, and the like are input to the controller 9. The controller 9 executes torque control of the engine 1, vehicle behavior control, sailing stop control described later, and the like based on the above-mentioned signals.

The controller 9 is a microcomputer including a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface). It is also possible to configure the controller 9 with a plurality of microcomputers.

The VDC unit 10 operates the braking device 8 provided on each drive wheel 7 in response to a signal from the controller 9.

FIG. 2 is a schematic configuration view of a brake system.

The brake system includes a brake fluid pressure generating device 20, a VDC unit 10, and a braking device 8. The braking device 8 comprises a brake caliper 8A and a brake rotor 8B.

The brake fluid pressure generator 20 includes a brake pedal 21, a negative pressure booster 22 as a negative pressure type booster, a VDC unit 10, and a master cylinder 23. The driver's brake depression force applied to the brake pedal 21 is boosted by the negative pressure booster 22, and the master cylinder 23 produces a brake fluid pressure. The negative pressure in the negative pressure booster is generated using the engine intake negative pressure.

The VDC unit 10 is interposed between the brake fluid pressure generator 20 and the brake caliper 8B. The VDC unit 10 has a hydraulic pressure pump 26 driven by an electric motor (not shown), a reservoir tank 25, and a solenoid valve 24 for switching a hydraulic pressure path.

When decelerating according to a driver's brake depression, the controller 9 controls the solenoid valve 24 so that the master cylinder 23 and the brake caliper 8B communicate with each other. Thus, the hydraulic pressure generated by the master cylinder 23 is supplied to the brake calipers 8B of the drive wheels 7. On the other hand, when the braking device 8 is used to control the behavior of the vehicle, the controller 9 controls the solenoid valve 24 to shut off the communication between the master cylinder 23 and the brake caliper 8B. Then, the controller 9 operates the hydraulic pressure pump 26 to supply the hydraulic pressure to the brake caliper 8B.

Next, the sailing stop control performed by the controller 9 will be described.

The sailing stop control is control for traveling by inertia by automatically stopping the engine 1 and releasing the forward clutch 3 when a predetermined sailing stop condition is satisfied during traveling. Hereinafter, a state in which the sailing stop control is performed to travel is referred to as sailing stop traveling. Moreover, sailing stop control may be described as SS control.

The sailing stop conditions include, for example, that the vehicle speed is equal to or higher than a preset lower limit vehicle speed, that the accelerator pedal and the brake pedal are not depressed, and that the forward range is selected in the automatic transmission 2. The lower limit vehicle speed is medium to high speed when the vehicle speed range is divided into low speed, medium speed, and high speed, and is preset by an experiment or the like.

The sailing stop control ends when the sailing stop release condition is satisfied during sailing stop traveling. The sailing stop release condition includes that the vehicle speed is less than the lower limit vehicle speed, that the accelerator pedal has been depressed, or that the brake pedal has been depressed.

Note that control for traveling with inertia by bringing the forward clutch 3 into the released state while driving the engine 1 at idle rotation speed is referred to as sailing idle control, and is distinguished from the above-described sailing stop control.

By the way, during sailing stop control, the forward clutch 3 is released to travel by inertia, so the so-called engine brake does not work. For this reason, when entering a downhill road during sailing stop traveling, the acceleration becomes larger than when engine braking is applied, and depending on the acceleration situation, it may be against the driver's intention. At this time, the driver is likely to step on the brake pedal to suppress the vehicle speed. When the brake pedal is depressed, the sailing stop release condition is satisfied, and the sailing stop control is ended. That is, if the driver enters the downward slope during sailing stop traveling, the sailing stop control is terminated by the driver's brake operation, and there is a high possibility that the fuel consumption improvement effect by the sailing stop control can not be sufficiently obtained.

Therefore, in the present embodiment, the controller 9 pre-reads whether or not there is a section where sailing stop control can be performed on the route, and prevents the driver from depressing the brake pedal when entering a downhill road. Execute control. Hereinafter, this control will be described in detail.

FIG. 3 is a flowchart showing a control routine executed by the controller 9.

In step S10, the controller 9 determines whether or not sailing stop control is being performed. If the above-described sailing stop condition is satisfied, it is determined that the operation is in progress.

When the sailing stop control is being performed, the controller 9 performs the prefetching of the road condition in the traveling direction in step S20. Specifically, the road gradient in the traveling direction is acquired from the map information of the navigation system.

Furthermore, the controller 9 can calculate the road grade, the estimated value of the vehicle weight of the vehicle, the traveling history of the vehicle when traveling on the current traveling route, and information acquired from the traveling history of other vehicles, and It reads information obtained by communication and data from acceleration sensors and camera sensors. The travel history of other vehicles is acquired by inter-vehicle communication. Then, the controller 9 pre-reads the current traveling state and the traveling state (for example, acceleration) on the road ahead. The weight of the vehicle can be estimated using the distance traveled since the last fueling and the number of occupants. Since the vehicle accelerates by gravity on the downhill road under sailing stop control, if the vehicle weight and the slope are known, the acceleration on the downhill slope can be estimated.

On the other hand, when the sailing stop control is not performed, the controller 9 ends this routine.

In step S30, the controller 9 determines whether the acceleration estimated in step S20 is the "acceleration contrary to the driver's intention" described above. The controller 9 executes the processing of step S40 if the acceleration is against the driver's intention, and otherwise executes the processing of step S60. Although not shown, in the present embodiment, when the current vehicle speed is higher than the vehicle speed at the start of the sailing stop control, it is determined that the acceleration is against the driver's intention. If the vehicle speed at the start of the sailing stop control is higher than, for example, 10 km / h, it may be determined that the acceleration is against the driver's intention.

In step S40, the controller 9 determines the amount of brake operation by the VDC unit 10 so as not to become an acceleration contrary to the driver's intention on the downhill to enter from here. Specifically, the necessary braking force is calculated using the slope of the downhill road and the estimated value of the vehicle weight of the vehicle, and the operation amount of the VDC unit 10 for generating the braking force is determined. Here, the "required braking force" is a braking force for preventing the acceleration against the driver's intention, for example, a braking force for suppressing the acceleration to a degree that does not exceed the speed limit.

The operating amount of the VDC unit 10 means the operating amount of the hydraulic pump 26. The relationship between the operation amount of the VDC unit 10 and the braking force differs depending on the VDC unit 10 used. Therefore, the amount of operation of the VDC unit 10 is determined by, for example, examining the table in advance by experiment etc. and searching the table with the calculated braking force.

In step S50, the controller 9 operates the VDC unit 10 based on the operation amount determined in step S40 when entering the downhill road. That is, the controller 9 determines the operation amount of the VDC unit 10 when entering the downhill road by feedforward control, and immediately generates the braking force when entering the downhill road.

On the other hand, when it is determined in step S30 that the acceleration is not against the driver's intention, the controller 9 limits the operation of the VDC unit 10 in step S60.

In step S70, the controller 9 determines whether or not the accelerator pedal is expected to be depressed. For example, based on the result pre-read in step S20, when there is an upward slope road ahead of the downward slope road, it is predicted that the accelerator pedal is depressed. When the depression of the accelerator pedal is predicted, the controller 9 executes the processing of step S80, and otherwise ends this routine.

In step S80, the controller 9 starts the engine 1 before the accelerator pedal is depressed. For example, the time required from the start of cranking to the start of engine 1 (hereinafter also referred to as the time required for engine start) and the time from when the driver enters the upward slope to when the driver depresses the accelerator pedal It is stored in the controller 9 in advance. Then, the controller 9 starts the cranking at a timing that goes back by the time required to start the engine from the timing when the driver depresses the accelerator pedal.

As described above, in this routine, when entering a downhill road during sailing stop traveling, the acceleration is suppressed by the VDC unit 10, so that the driver depresses the brake pedal and the sailing stop cancellation condition is satisfied. It can be avoided. As a result, the fuel consumption improvement effect by sailing stop traveling can be further enhanced.

In S50, the controller 9 may perform feedback control of the operation amount of the VDC unit 10 based on the actual vehicle speed. The braking force by the VDC unit 10, the friction of each part of the vehicle, and the running resistance of the drive wheel 7 have variations due to individual differences and aging, so if feedback control based on the actual vehicle speed is performed, acceleration suppression is insufficient. And to suppress the acceleration more than necessary.

FIG. 4 is a timing chart when the control routine described above is executed. FIG. 5 is a timing chart when the above-described control routine is not executed for comparison. The control represented by the timing chart of FIG. 5 is not included in the scope of the present invention.

In both of FIG. 4 and FIG. 5, the flat road is sailing-stopped from timing 0 to timing T1.

In FIG. 4, the controller 9 predicts that it will be a downward slope road from timing T1 to timing T3 and will become an upward slope road after timing T3 by performing pre-reading of the road condition during this time. Furthermore, the controller 9 also determines the amount of operation of the VDC unit 10 when entering the downhill. Then, when the vehicle enters the downhill road at timing T1, the controller 9 operates the VDC unit 10 to suppress the increase in the vehicle speed. As a result, the driver does not operate the brake and sailing stop control is continued.

On the other hand, in FIG. 5, when the vehicle approaches a downhill road, the vehicle speed increases with a greater acceleration than in FIG. As a result, the driver depresses the brake pedal at timing T2, and the sailing stop control ends.

In addition, the controller 9 also pre-reads that it is an upward slope path after timing T3. Then, the controller 9 controls the sailing stop in the middle of the downhill road (timing T2.5) so that the engine 1 is started at the time (T4) when the driver enters the uphill road and the driver depresses the accelerator pedal. End and start the engine 1. Thereby, it is possible to suppress an acceleration delay when the accelerator pedal is depressed upon entering the ascending road.

As described above, while sailing stop control can be continued only up to timing T2 in FIG. 5, sailing stop control can be continued up to timing T2.5 in FIG. 4, so FIG. 4 corresponds to FIG. Compared with it, the fuel consumption improvement effect by sailing stop control is large.

As described above, in the present embodiment, the automatic transmission 2 connected to the engine (drive source) 1 for traveling and the engine 1 and having the forward clutch 3 (the fastening element for forward movement), the brake pedal depression force of the driver A control method of a vehicle including a negative pressure booster (negative pressure type booster) 22 for assisting is provided. In this control method, when the sailing stop satisfaction condition (drive source stop condition) set in advance is satisfied during traveling, sailing stop control is performed to stop the engine 1 and release the forward clutch 3. And, while the sailing stop control is being performed, by operating the brake device that generates the braking force without using the negative pressure booster 22 and by the driver's operation, that is, by operating the VDC unit 10, Suppress the contrary acceleration. As a result, the opportunity for the sailing stop control to end due to the driver's depression of the brake pedal can be reduced, and the fuel consumption improvement effect by the sailing stop control can be further enhanced.

Note that "acceleration contrary to the driver's intention" in the present embodiment is, for example, acceleration by entering a downhill road during execution of sailing stop control.

In the present embodiment, when it is predicted that the road condition in the vehicle traveling direction is pre-read and the vehicle enters a downward slope, the acceleration of the vehicle on the downward slope is estimated based on the pre-read downward slope. The operation amount of the VDC unit 10 is determined in accordance with the obtained acceleration. As described above, since the operation amount of the VDC unit 10 is determined before the vehicle accelerates, unnecessary acceleration can be prevented when entering a downhill road. Further, since the operation amount of the VDC unit 10 is determined so as to suppress the acceleration on the down slope road, the vehicle behavior is close to the state in which the engine brake is in effect, which makes it difficult for the driver to feel discomfort.

In this embodiment, when entering the downhill road during execution of sailing stop control, the VDC unit 10 is operated, and feedback control of the operation amount of the VDC unit 10 is performed based on the actual acceleration. As a result, it is possible to absorb the variations due to the individual difference and the secular change of the VDC unit 10 and each part of the vehicle, and to further reduce the sense of discomfort to the driver.

In the present embodiment, the acceleration of the vehicle in the road condition read ahead and down slope is obtained by the map information of the navigation system, the estimated value of the vehicle weight of the vehicle, the previous travel history of the vehicle, and other vehicles On the basis of at least one of travel history, information obtained by road-vehicle communication, data of an acceleration sensor, or data of an on-vehicle camera. By using these pieces of information and data, it is possible to determine the operating amount of the VDC unit 10 with higher accuracy, and further, it is possible to improve the determination accuracy as to whether or not the acceleration is against the driver's intention.

In the present embodiment, when an accelerator depression operation by the driver is predicted during execution of the sailing stop control, the engine 1 is restarted before the accelerator depression operation is performed. If the engine 1 is started after an accelerator depression operation, acceleration can not be performed until the engine 1 starts. However, according to the present embodiment, such an acceleration delay can be prevented, and drivability during sailing stop control is improved.

In the embodiment described above, the VDC unit 10 is described as "the brake device that generates the braking force without using the negative pressure booster 22 and not by the driver's operation", but is limited to this. is not. Those that perform the same function, such as a regenerative brake system or a brake-by-wire system, may be used.

As mentioned above, although the embodiment of the present invention was described, the above-mentioned embodiment showed only a part of application example of the present invention, and in the meaning of limiting the technical scope of the present invention to the concrete composition of the above-mentioned embodiment. Absent.

Claims (8)

A control method of a vehicle comprising: a drive source for traveling; an automatic transmission connected to the drive source and having a fastening element for forward movement; and a negative pressure type booster for assisting a driver's brake pedal depression force.
When a preset drive source stop condition is satisfied during traveling, sailing stop control is performed to stop the drive source and release the forward fastening element.
During the execution of the sailing stop control, acceleration that is against the driver's intention is suppressed by operating the brake device that generates the braking force without using the negative pressure type booster and without the driver's operation. Vehicle control method. In the control method of a vehicle according to claim 1,
The vehicle control method, wherein the acceleration contrary to the driver's intention is acceleration by entering a downhill road during execution of the sailing stop control. In the control method of a vehicle according to claim 2,
Look ahead to the road conditions in the direction of vehicle travel,
When it is predicted that the vehicle enters a downward slope, the acceleration of the vehicle on the downward slope is estimated based on the previously read downward slope, and the operation amount of the brake device is determined according to the estimated acceleration. , How to control the vehicle. In the control method of a vehicle according to claim 3,
A control method of a vehicle, operating the brake device and performing feedback control of an operation amount of the brake device based on an actual acceleration, when entering a downhill road during execution of the sailing stop control. The control method of a vehicle according to claim 3 or 4
The navigation system's map information, the estimated value of the vehicle weight of the vehicle, the previous travel history of the vehicle, the travel history of other vehicles obtained by inter-vehicle communication And a control method of a vehicle based on at least one of information obtained by road-to-vehicle communication, data of an acceleration sensor, or data of an on-vehicle camera. In the vehicle control method according to any one of claims 1 to 5,
A control method of a vehicle, which restarts the drive source before an accelerator depression operation is performed, when an accelerator depression operation by a driver is predicted during execution of the sailing stop control. In a control device of a vehicle having an automatic transmission having a forward engaging element connected to an internal combustion engine, which is capable of stopping the internal combustion engine while traveling and releasing the forward engaging element.
A booster that assists the driver's brake pedal force,
When the brake hydraulic pressure is generated by the booster and a brake hydraulic pressure control device capable of generating the brake hydraulic pressure by the actuator without using the booster, and a drive source stop condition set in advance during traveling is satisfied. A control unit for performing a sailing stop control of stopping the drive source and releasing the forward fastening element;
In a control device of a vehicle comprising
The brake fluid pressure control device generates a brake fluid pressure by an actuator without using the boosting device and stops the internal combustion engine while stopping the internal combustion engine while traveling and releasing the forward coupling element. The control device of the vehicle which suppresses acceleration by operating a control device. In the control device for a vehicle according to claim 7,
The control device for a vehicle according to claim 1, wherein the booster is a negative pressure booster that receives an intake negative pressure of an internal combustion engine and assists a brake pedal depression force of a rolling member by the negative pressure.

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