JP2008195119A - Spring brake actuator - Google Patents

Abstract

A spring brake actuator is provided that can prevent moisture in the atmosphere from entering a spring chamber.
A housing 22 having a space therein, a diaphragm 28 that divides the interior space of the housing 22 into a spring chamber 46 and a pressure chamber 45, and a diaphragm 28 disposed inside the spring chamber 46 so that the diaphragm 28 is located on the pressure chamber side. A coil spring 54 that urges and activates the brake device using the urging force. The coil spring 54 can be contracted by supplying pressure to the pressure chamber 45 and has an opening provided in the housing 22. In the spring brake actuator, which can be contracted by the operating member 100 inserted into the spring chamber from the outside through the portion 24c, the spring chamber 46 is formed so that the inside of the spring chamber 46 is sealed when the opening 24c is sealed. A pipe 66 for allowing the inside of the spring chamber 46 to communicate with the atmosphere is detachably attached to the opening 24c.
[Selection] Figure 3

Description

  The present invention relates to a spring brake actuator that operates a brake by using a resilient force of a compression coil spring.

In general, large vehicles such as buses, trucks, and trailers include a parking brake that brakes by operating a parking brake lever in addition to a normal brake that is braked by a driver's brake pedal operation.
In this type of parking brake, the brake actuator is generally operated by operating the parking brake lever, and the brake shoe is generally brought into contact with the drum for braking by the operation of the brake actuator. Conventionally, a spring brake actuator has been proposed as the brake actuator.

  In this spring brake actuator, the pressure chamber and the spring chamber are adjacent to each other via a diaphragm, and the pressure of the compressed air flowing into or out of the pressure chamber and the elastic force of the coil spring provided in the spring chamber are used. The diaphragm is configured to be movable, and the brake is operated by moving the operating rod connected to the diaphragm. Specifically, when the force due to the pressure of compressed air is stronger than the spring force of the coil spring, the diaphragm is moved to the coil spring chamber side and the operating rod is retracted so that the brake is released. It has become. On the other hand, when the spring force of the coil spring is stronger than the force due to the pressure of the compressed air, the brake is operated by moving the diaphragm to the pressure chamber side and projecting the operating rod. .

The spring brake actuator includes a bypass pipe for communicating the spring chamber with the atmosphere. This bypass pipe prevents the spring chamber from becoming negative pressure and prevents the biasing force of the coil spring from being hindered in the spring chamber.
Further, an opening for inserting the brake release bolt into the spring chamber is formed in the housing forming the spring chamber. The brake release bolt is for releasing the brake by the coil spring by manually contracting the coil spring at the time of maintenance, for example. When releasing the brake, the brake release bolt is inserted into the spring chamber from the opening portion so that one end of the coil spring is inserted. It is engaged with the supporting spring seat member. The opening is normally closed with a cap so that water and dust cannot enter the spring chamber from the opening. The cap is attached by screwing a fastening member such as a screw into a screw hole provided in the wall portion of the housing (see, for example, Patent Document 1).
JP 2005-30555 A

  However, in the above-described configuration, moisture in the atmosphere may enter the spring chamber from the bypass pipe that can communicate with the atmosphere, the opening for inserting the brake release bolt, and the screw hole for attaching the cap. The moisture in the atmosphere comes into contact with a coil spring disposed in the spring chamber. Although the coil spring is painted to prevent corrosion, if the coating is worn or peeled off due to expansion or contraction of the coil spring or deterioration over time, the coil spring may be corroded by moisture in the contacted atmosphere. was there.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a spring brake actuator that makes it difficult for moisture in the atmosphere to enter the spring chamber.

In the present invention, a housing having a space inside, a diaphragm that divides the internal space of the housing into a spring chamber and a pressure chamber, and arranged inside the spring chamber to urge the diaphragm toward the pressure chamber, A coil spring that operates the brake device using an urging force, and the coil spring can be contracted by supplying pressure to the pressure chamber, and the spring is externally provided through an opening provided in the housing. In the spring brake actuator, which can be contracted by an operating member inserted into the room, the spring chamber is formed so that the inside of the spring chamber is hermetically sealed when the opening is sealed, and the spring is formed in the opening. The interior of the chamber is detachably attached with a conduit for communicating with the atmosphere.
According to this configuration, the passage through which moisture in the atmosphere can enter the spring chamber can be limited only to the opening for inserting the operating member into the spring chamber.

In this case, the attachment portion of the pipe line may be formed of a rubber member that can be elastically deformed.
According to this configuration, the pipeline can be easily attached and detached when the brake is manually released during maintenance or the like. In addition, the opening can be easily sealed by elasticity so that moisture can hardly enter.

  According to the present invention, the possibility of moisture entering the spring chamber can be reduced, and the coil spring can be hardly corroded by moisture in the atmosphere. In addition, by attaching the bypass conduit to the opening in a detachable manner, the opening can be used also as an inlet / outlet of the bypass conduit. Therefore, the passage through which moisture in the atmosphere can enter the spring chamber can be limited only to the opening, and the conventional functions of manual release of the brake and attachment of a bypass pipe that communicates the spring chamber with the atmosphere can be exhibited. Can be.

  Furthermore, by forming the attachment portion of the pipe line with a rubber member that can be elastically deformed, the pipe line can be easily attached and detached when the brake is manually released in maintenance. Thereby, maintainability can be improved. In addition, the opening can be sealed by elasticity so that moisture can hardly enter. Furthermore, since the conventional cap and the fastening member for attaching the cap are not required, the number of parts of the spring brake actuator can be reduced.

  Hereinafter, a spring brake actuator (spring type brake actuator) according to an embodiment of the present invention will be described with reference to FIGS. Note that the directions such as up and down and left and right used in the following description are based on FIG.

  A specific structure of the brake actuator 20 is shown in FIGS. Here, FIG. 1 shows a parking brake operation state by the brake actuator 20, and FIG. 2 shows a parking brake release state by the brake actuator 20. FIG. 3 is a partially enlarged view of the spring chamber 46 shown in FIG.

  In this brake actuator 20, a service brake actuator 20A that performs a brake operation in conjunction with a pedal movement that a driver steps on and a spring brake actuator 20B that performs a parking brake operation separately from the pedal movement are combined in tandem. Is.

  The spring brake actuator 20B according to the present invention is not necessarily used for parking brakes but can be used for service brakes. Further, the present invention can be applied to an independent spring brake actuator.

As shown in FIG. 1, the service brake actuator 20A has a housing divided into two parts, a cylinder side housing 22 and an intermediate housing 23 located on the left side of the cylinder side housing 22. A first diaphragm 26 is provided.
Further, as shown in FIG. 1, the housing of the spring brake actuator 20B is constructed by splitting left and right into an intermediate housing 23 and a spring housing housing 24 located further to the left of the intermediate housing 23. Is provided with a second diaphragm 28.

First, the service brake actuator 20A will be described with reference to FIG.
The first diaphragm 26 partitions an internal space surrounded by the cylinder side housing 22 and the intermediate housing 23, and includes an atmosphere chamber 35 on the cylinder side housing 22 side (right side in FIG. 1) and an intermediate housing 23 side (in FIG. 1). The first pressure chamber 36 on the right side of the center is partitioned.

  As shown in FIG. 1, an operation rod 40 having a flange 37 at one end is in contact with the surface of the first diaphragm 26 on the atmosphere chamber 35 side via the flange 37. The piston 30 is connected to the other end of the operation rod 40 via a pin 42.

  An air communication port 22c for allowing the air chamber 35 to communicate with the atmosphere is provided at a lower portion of the portion (the air chamber forming portion 22b) that forms the air chamber 35 of the cylinder-side housing 22. A first supply port 23 d for supplying compressed air into the first pressure chamber 36 is provided on the upper surface portion of the intermediate housing 23.

  A pneumatic supply source is connected to the first supply port 23d communicating with the first pressure chamber 36 via a brake valve (not shown). When the brake pedal is depressed, compressed air is supplied from the first supply port 23d into the first pressure chamber 36 through the brake valve, while the compressed air in the first pressure chamber 36 is first supplied as the pedal depression is loosened. It escapes through the port 23d.

Next, the spring brake actuator 20B will be described with reference to FIG.
The spring housing housing 24 is formed in a cap shape that covers the opening of the intermediate housing 23. An internal space surrounded by the intermediate housing 23 and the spring housing housing 24 is partitioned by the second diaphragm 28. The second diaphragm 28 defines a second pressure chamber 45 on the intermediate housing 23 side (center left side in FIG. 1) and a spring chamber 46 on the spring housing housing 24 side (left side in FIG. 1).

  Between the central portion of the second diaphragm 28 and the central portion of the first diaphragm 26, a transmission rod 50 for transmitting force between the first diaphragm 26 and the second diaphragm 28 is interposed. Further, a second supply port 23 e for supplying compressed air into the second pressure chamber 45 is provided on the upper surface portion of the intermediate housing 23.

  A compression coil spring 54 is loaded in the spring chamber 46. The compression coil spring 54 is expanded and contracted in a direction substantially parallel to the displacement direction of the second diaphragm 28, that is, the posture in which the central axis of the compression coil spring 54 and the central axis of the spring brake actuator 20 </ b> B coincide with each other. It is loaded inside.

  In order to reduce the axial dimension in the most contracted state, the compression coil spring 54 is of a so-called barrel shape (a shape in which the intermediate portion swells in the radial direction compared to the upper and lower ends). The outer surface of the compression coil spring 54 is coated with anticorrosion and rust.

As shown in FIGS. 1 to 3, spring seat members 56 and 58 for stabilizing the position of the compression coil spring 54 at the center position are provided in the spring chamber 46. These spring seat members 56 and 58 are made of, for example, iron or aluminum, and the outer surface thereof is coated with anticorrosion.
The spring seat member 56 is interposed between one end portion 54 a of the compression coil spring 54 and the second diaphragm 28, and the spring seat member 58 is disposed between the other end portion 54 b of the compression coil spring 54 and the spring housing housing 24. It is interposed between the top wall 24b.

  As shown in FIGS. 1 to 3, the one spring seat member 56 has a disc-shaped spring seat body 56 m, and the spring seat body 56 m is in close contact with the spring chamber side surface of the second diaphragm 28. It is arranged. The relative position of the spring seat main body 56m and the second diaphragm 28 can be fixed by using the frictional force generated by pressing the compression coil spring 54. However, the spring seat main body 56m and the second diaphragm 28 can be positively fixed by bonding them together. Also good.

  As shown in FIG. 3, a thick spring restraining portion 56a is formed at the center of the spring seat body 56m. One end portion 54a of the compression coil spring 54 is fitted into the spring restraining portion 56a, so that the radial movement is restricted. Further, a thicker boss portion 56b is formed at the center of the spring restraint portion 56a, and the brake releasing bolt 100 (see FIG. 4) is engaged with the center of the boss portion 56b during maintenance or the like. A key hole 56c (see FIGS. 1 and 2) is formed. In addition, a flat portion 56f that receives the elastic force of the compression coil spring 54 is formed in a circumferential shape in a portion outside the spring restraint portion 56a.

  Further, an air pressure supply source is connected to the second supply port 23e via a parking brake valve (not shown), and the second supply port 23e is connected to the second supply port 23e through the parking brake valve when the parking brake operation is not performed. While high pressure air is supplied into the pressure chamber 45, high pressure air in the second pressure chamber 45 is released from the second supply port 23e through the parking brake valve when a parking brake operation is performed.

  On the other hand, an opening 24c is formed at the tip of the spring housing housing 24 (the left end in FIG. 1). The opening 24c is the only opening that communicates with the spring chamber 46. When the opening 24c is sealed with a lid or the like, the inside of the spring chamber 46 is sealed.

  As shown in FIGS. 1 and 2, the opening 24 c is connected to an opening 22 d formed in the upper part of the cylinder-side housing 22 via a bypass conduit 66. Specifically, the bypass pipe 66 has a connection tube 66a connected to the opening 22d side, a connection tube 66b connected to the opening 24c side, and these connection tubes 66a and 66b connected to both ends. And a pipeline 66c. Thereby, the atmosphere flowing into the atmosphere chamber 35 from the atmosphere communication port 22c of the cylinder side housing 22 flows into the spring chamber 46 from the opening 24c through the bypass conduit 66. Thereby, the inside of the spring chamber 46 does not become a negative pressure.

  The connection tube 66b is formed of a rubber material having elasticity. Further, a groove 66b1 (see FIG. 3) is formed on the outer peripheral surface of the distal end of the connection tube 66b in the circumferential direction. This groove 66b1 is adapted to be fitted into the peripheral edge of the opening 24c by elasticity. With this structure, the connection tube 66b is detachably attached to the opening 24c by elasticity. Further, in a state where the connection tube 66b is attached, the peripheral edge portion of the opening 24c is completely sealed. In other words, the atmosphere outside the housing 22 does not enter the atmosphere except for entering the inside of the spring chamber 46 through the bypass conduit 66.

Further, the connection tube 66a is also formed of a rubber material similarly to the connection tube 66b, and is detachably attached by fitting a groove formed in the circumferential direction into the peripheral portion of the opening 22d. Yes.
Furthermore, the pipe line 66c is similarly formed of a rubber material, and is connected without leakage of air at the connection part with the connection tubes 66a and 66b. Further, the pipe line 66c may not be a rubber material but may be a pipe made of metal such as iron or aluminum.

FIG. 4 is a cross-sectional view showing the brake actuator shown in FIGS. 1 and 2 in a state where the parking brake by the spring brake actuator 20B is manually released.
From the opening 24c described above, the brake releasing bolt 100 is inserted during maintenance or the like. A flange portion 100a is provided on a part of the outer peripheral surface of the tip portion of the brake releasing bolt 100 (the portion engaging with the key hole 56c). Then, the flange portion 100a is engaged with the end surface of the key hole 56c by rotating the brake release bolt 100 through the opening 24c through the key hole 56c and then rotating about 90 degrees.

  In addition, a nut 101 that is screwed with a brake release bolt and a washer 102 that receives the nut 101 are prepared in the outer portion of the opening 24. When the nut 101 is rotated, the brake releasing bolt 100 can be moved in the axial direction. As a result, the spring seat member 56 can be moved toward the opening 24c against the urging force of the compression coil spring 54.

  Next, the operation of the spring brake actuator 20B according to the embodiment of the present invention will be described.

  First, when the parking brake is operated by the driver when the vehicle is stopped, the high-pressure air in the second pressure chamber 45 is released to the outside through the second supply port 23e and the parking brake valve (not shown). The central portion of the second diaphragm 28 is pushed in the direction of decreasing the volume of the second pressure chamber 45 by the elastic force of the spring 54 and is in the position shown in FIG. 1, and further, the pushing force is transmitted to the transmission rod 50 and the first diaphragm. 26, the operating rod 40, and the piston 30 are also transmitted, and the transmission shaft engaged therewith advances toward the brake cylinder. As the transmission shaft advances, a wedge (not shown) interrupts between both telescopic rods of the brake cylinder, and extends the brake cylinder to actuate the brake.

On the other hand, when the parking brake operation is released from the state where the parking brake is applied, high pressure air is supplied from the second supply port 23e into the second pressure chamber 45. The direction in which the central portion of the second diaphragm 28 decreases the volume of the spring chamber 46 against the elastic force of the compression coil spring 54 (ie, while the compression coil spring 54 contracts) due to the force (leftward in FIG. 1). 2), the front surface of the spring restraint portion 56a of the spring seat member 56 moves to a position where it contacts the shaft end 58c of the spring seat member 58 as shown in FIG. Along with this, the transmission shaft, the piston 30 and the operating rod 40 receiving reaction force from the brake cylinder via a wedge (not shown) also move to the position of FIG. Thus, when the transmission shaft moves backward from the brake cylinder, the brake cylinder is contracted and the brake is released.
As shown in FIG. 2, the compression coil spring 54 has both spring seat members 56, 58 accessible to the position where the shaft end 58c of the cylindrical portion 58a hits the front surface of the spring restraint portion 56a. The volume of 46 can be made as small as possible.

  When the service brake is operated from this parking brake release state (in this embodiment, the brake pedal is depressed), high pressure air is introduced into the first pressure chamber 36 through the first supply port 23d, The first diaphragm 26, the operating rod 40, and the piston 30 are pushed toward the brake cylinder. As a result, the transmission shaft moves forward toward the brake cylinder side, so that the brake cylinder extends again and the brake is applied.

  In this configuration, for example, during maintenance (when high pressure air is not introduced into each pressure chamber), the second diaphragm 28 in FIG. You may want to release the parking brake manually. At this time, as shown in FIG. 4, the operator removes the connection tube 66b of the bypass conduit 66 from the opening 24c, inserts a brake release bolt from the opening 24c, and enters the key hole 56c of the spring seat member 56. The brake is released by engaging (rotating) the brake release bolt in the direction in which the compression coil spring 54 compresses. Further, except for maintenance, by attaching the connection tube 66b to the opening 24c, the atmosphere in the vicinity of the opening 24c is prevented from entering from the opening 24c, and the atmosphere is entered only from the atmosphere communication port 22c. become.

  According to the spring brake actuator according to the embodiment of the present invention, the distal end portion of the spring housing housing 24 communicates with the inside of the spring chamber 46, and the position of the second diaphragm 28 is set from the outside of the spring housing housing 24 to the coil spring. The spring chamber 46 is formed so that the opening 24c into which the brake release bolt for moving against the urging force is inserted is formed, and the inside of the spring chamber 46 is sealed when the opening 24c is sealed. Thus, the risk of moisture in the atmosphere entering the spring chamber 46 can be reduced. As a result, the possibility of moisture entering the spring chamber 46 can be reduced. As a result, the coil spring can be made difficult to corrode with moisture in the atmosphere, and a spring brake actuator having excellent water resistance can be provided.

In addition, by attaching the bypass conduit 66 for allowing the inside of the spring chamber 46 to communicate with the atmosphere to the opening 24c in a detachable manner, the opening 24c and the attachment port of the bypass conduit 66 can be shared. As a result, it is possible to reduce the possibility of moisture in the atmosphere entering the spring chamber 46 as compared with a structure in which a separate attachment portion for the bypass pipe 66 is provided in addition to the opening 24c. As a result, the possibility of moisture entering the spring chamber 46 can be reduced. Thereby, a coil spring can be made hard to corrode with the water | moisture content in air | atmosphere.
Conventionally, the cap is fixed with a fastening member such as a screw in order to seal the opening 24c. However, since the cap and the fastening member can be eliminated, the number of parts can be reduced.

  Furthermore, since the bypass pipe 66 is piped and the atmosphere is taken in from the atmosphere communication port 22c, the possibility of moisture and dust in the atmosphere entering the spring chamber 46 can be reduced.

  Furthermore, since the connection tube 66b of the bypass conduit 66 is formed of a rubber member that can be elastically deformed, the connection tube 66b can be easily attached and detached when the parking brake is manually released during maintenance. Thereby, maintainability can be improved. In addition, the opening 24c can be sealed by elasticity to make it difficult for moisture to enter.

  Further, in the present embodiment, the brake actuator 20 has been described. However, as shown in FIG. 5, the spring brake actuator 20 </ b> B alone can be used as a parking brake alone. In the spring brake actuator 200 shown in FIG. 5, the service brake actuator 20A shown in FIGS. 1 and 2 is omitted. More specifically, the shapes of the cylinder side housing 220 and the intermediate housing 230 are appropriately changed and assembled, and other configurations and functions are the same as those of the spring brake actuator 20B described above.

It is sectional drawing which shows the state in which the parking brake was applied in the spring brake actuator which concerns on embodiment of this invention. It is sectional drawing which shows the state by which both the parking brake and service brake of the spring brake actuator which concern on embodiment of this invention were cancelled | released. It is an expanded sectional view of the spring chamber shown in FIG. FIG. 2 is a cross-sectional view showing a state in which a brake releasing bolt is inserted from an opening and the brake is manually released in the state of FIG. It is a partial cross section figure which shows the spring brake actuator of FIG.

Explanation of symbols

20 Brake Actuator 20A Service Brake Actuator 20B Spring Brake Actuator 22 Cylinder Side Housing (Housing)
22b Atmospheric chamber forming portion 22c Atmospheric communication port 22d Opening portion 23 Intermediate housing 23b First pressure chamber forming portion 23c Second pressure chamber forming portion 23d First supply port 23e Second supply port 24 Housing housing 24b Top wall 24c Opening portion 26 Second 1 Diaphragm 28 2nd Diaphragm 30 Piston 35 Air Chamber 36 First Pressure Chamber 37 Flange 40 Operation Rod 42 Pin 45 Second Pressure Chamber (Pressure Chamber)
46 Spring chamber 50 Transmission rod 54 Compression coil spring (coil spring)
54a, 54b End portions 56, 58 Spring seat member 56a Restraint portion 56b Boss portion 56c Key hole 56f Plane portion 56m Seat body 58a Cylindrical portion 58b Flange portion 58c Shaft end 62 Auxiliary coil spring 66 Bypass conduit 66a, 66b Connection tube 66b1 Groove portion 66c Pipe line 100 Brake release bolt (operation member)
100a Flange portion 101 Nut 102 Washer 200 Spring brake actuator 220 Cylinder side housing 230 Intermediate housing

Claims (2)

A housing having a space inside, a diaphragm that divides the internal space of the housing into a spring chamber and a pressure chamber, and arranged inside the spring chamber to urge the diaphragm toward the pressure chamber, and use the urging force And a coil spring for operating the brake device,
The coil spring can be contracted by supplying pressure to the pressure chamber, and can also be contracted by an operation member inserted into the spring chamber from the outside through an opening provided in the housing. In
The spring chamber is formed so that the inside of the spring chamber is hermetically sealed when the opening is sealed, and a conduit for allowing the inside of the spring chamber to communicate with the atmosphere is detachably attached to the opening. Spring brake actuator characterized by   The spring brake actuator according to claim 1, wherein the attachment portion of the pipe line is formed of a rubber member that can be elastically deformed.

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