JP2008162309A - Spring brake actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spring brake actuator hardly peeling off coating of a coil spring even if the coil spring is expanded/contracted based on brake action. <P>SOLUTION: The spring brake actuator is provided with a housing 22 having a space at the inside and a diaphragm 28 for partitioning the internal space of the housing 22 to a spring chamber 46 and a pressure chamber 45. The coil spring 54 for urging the diaphragm 28 to a pressure chamber side is arranged at the inside of the spring chamber 46. Sheet members 70, 72 made of resin are interposed between both ends 54a, 54b of the coil spring 54 and spring seats 56, 58 for supporting the both ends 54a, 54b respectively. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a spring brake actuator that operates and releases a brake by using the elastic 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 pressure of compressed air is stronger than the spring force of the coil spring, the brake is released by moving the diaphragm toward the coil spring chamber and moving the operating rod backward. ing. On the other hand, when the spring force of the coil spring is stronger than the pressure of the compressed air, the diaphragm moves to the pressure chamber side and the operating rod protrudes to operate the brake (for example, , See Patent Document 1).

The spring chamber is provided with a bypass line communicating with the atmosphere so that the inside thereof does not become a negative pressure. Moreover, since moisture in the atmosphere may enter the spring chamber from the bypass pipe, the outer surface of the coil spring is coated with anticorrosion.
JP 2005-30555 A

  However, each time the coil spring expands or contracts, the both ends of the coil spring come into contact with and rub against the spring seats that support the both ends of the coil spring. Thereby, both ends of the coil spring and the coating of the spring seat may be peeled off or worn out.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a spring brake actuator in which the coating of the coil spring is difficult to peel even if the coil spring expands and contracts based on the brake operation.

In the present invention, a coil spring comprising a housing having a space inside and a diaphragm defining the space inside the housing into a spring chamber and a pressure chamber, and biasing the diaphragm toward the pressure chamber inside the spring chamber. In the spring brake actuator in which is provided, a resin sheet member is interposed between both end portions of the coil spring and spring seats respectively supporting the both end portions.
According to this configuration, even if the coil spring expands and contracts with the brake operation, both end portions of the coil spring do not come into contact with the spring seat, respectively.

In this case, the housing may include a passage through which the inside of the spring chamber communicates with the atmosphere.
According to this configuration, the spring chamber can be prevented from becoming negative pressure, and even if moisture in the atmosphere enters the inside of the spring chamber, the coil spring can be made difficult to corrode.

  According to the present invention, there is provided a housing having a space inside, and a diaphragm that defines the internal space of the housing into a spring chamber and a pressure chamber, and biases the diaphragm toward the pressure chamber inside the spring chamber. In the spring brake actuator in which the coil spring is disposed, both end portions of the coil spring are provided by interposing a resinous sheet member between both end portions of the coil spring and spring seats respectively supporting the both end portions. The spring seat is in direct contact with the resin sheet. For this reason, even if the coil spring expands and contracts with the brake operation, both ends of the coil spring and the respective spring seats do not come into contact with each other, so that they do not rub against each other. In addition, the base of the spring seat is not exposed, and corrosion of the coil spring and the spring seat can be prevented. Thereby, the lifetime of the spring brake actuator can be improved and the reliability can be increased.

  Hereinafter, a spring brake actuator (spring 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). Specifically, as shown in FIG. 4, from the right side, a small-diameter portion 54a, a medium-diameter portion 54c, a large-diameter portion 54d, a medium-diameter portion 54e, and a small-diameter portion 54b are arranged in order of 5 turns. The small-diameter portions 54a and 54b are loaded in the spring chamber 46 so as to contact spring seat members 56 and 58, which will be described later in detail. The outer surface of the compression coil spring 54 is coated for 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 small diameter portion 54 a of the compression coil spring 54 and the second diaphragm 28, and the spring seat member 58 is accommodated with the other small diameter portion 54 b of the compression coil spring 54 in the spring direction. It is interposed between the top wall 24 b of the housing 24.

  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. The spring restraint portion 56 a has an outer diameter that is slightly smaller than the inner diameter of the small diameter portion 54 a on the diaphragm side of the compression coil spring 54. The compression coil spring 54 is restricted from moving in the radial direction by fitting the small diameter portion 54a outside the spring restraining portion 56a. Further, a thicker boss portion 56b is formed at the center of the spring restraint portion 56a, and a key hole 56c (FIGS. 1 and 5) for engaging a jig at the time of maintenance or the like is formed at the center of the boss portion 56b. 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.

As shown in FIGS. 1 to 3, a resin sheet member 70 is interposed between the flat portion 56 f and the compression coil spring 54 so as to cover the flat portion 56 f. As shown in FIG. 5A, the sheet member 70 has an opening 70a formed at the center of the disk shape. The size of the opening 70a is larger than the outer diameter of the spring restraining portion 56a, and the flat portion 70b of the seat member 70 contacts the entire surface of the flat portion 56f in a state where the seat member 70 is attached to the spring seat member 56. It is like that. Further, a part of the opening 70 a is formed with a notch 70 c for avoiding a rotation stopper (not shown) protruding from the spring seat member 56. This detent prevents the attached seat member 70 and the compression coil spring 54 from rotating in the circumferential direction.
The seat member 70 is provided so that the small diameter portion 54a of the compression coil spring 54 and the flat portion 56f of the spring seat member 56 do not directly contact each other. In addition, as shown in FIG. 2, the size of the sheet member 70 includes not only the small diameter portion 54a of the compression coil spring 54 but also the medium diameter portion 54c and the flat surface portion 56f in a state where the compression coil spring 54 is compressed. Sufficient size is secured to prevent contact.

  The material of the sheet member 70 is determined based on the material of the compression coil spring 54 and the magnitude of the spring load, and is selected from materials having a small friction coefficient against the compression coil spring 54 and having a high compressive strength. Yes. The sheet member 70 also has an effect of reducing the contact sound between the small diameter portion 54a and the flat portion 56f.

  As shown in FIGS. 1 to 3, the other spring seat member 58 includes a cylindrical portion 58 a and a flange portion 58 b that spreads radially outward from the axial end thereof. The flange portion 58 b is interposed between the small diameter portion 54 b and the top wall 24 b of the spring housing housing 24 in a state where the small diameter portion 54 b in the axial direction of the compression coil spring 54 is fitted to the outside of the cylindrical portion 58 a.

Further, as shown in FIGS. 1 to 3, a resin sheet member 72 is interposed between the flange portion 58b and the compression coil spring 54 so as to cover the plane of the flange portion 58b. As shown in FIG. 5B, the sheet member 72 has a circular hole 72a formed at the center of the disk shape, like the sheet member 70. The size of the circular hole 72a is as follows. The plane portion 72b of the seat member 72 is in contact with the entire surface of the plane portion of the flange portion 58b in a state where the size is larger than the size of the cylindrical portion 58a and the seat member 72 is attached to the spring seat member 58.
The seat member 72 has a sufficient size so that the small diameter portion 54b and the medium diameter portion 54e of the compression coil spring 54 and the plane of the flange portion 58b do not directly contact each other. The sheet member 72 is made of the same material as the sheet member 70.

  The inside of the spring chamber 46 is communicated with the atmosphere chamber 35 of the service brake actuator 20A through the bypass conduit 66, and is opened to the atmosphere through the atmosphere communication port 22c. On the other hand, an air pressure supply source is connected to the second supply port 23e communicating with the second pressure chamber 45 via a parking brake valve (not shown), and when the parking brake is not operated, the second supply port 23e passes through the parking brake valve. The compressed air in the second pressure chamber 45 is released from the second supply port 23e through the parking brake valve when the parking brake operation is performed while the compressed air is supplied from the second supply port 23e into the second pressure chamber 45. It has become.

  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 compressed air in the second pressure chamber 45 is released to the outside through the second supply port 23e and a 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. The forward movement of the transmission shaft extends the brake cylinder to act on the brake.

On the other hand, when the parking brake operation is released from the state where the parking brake is applied, the compressed 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. Accordingly, the transmission shaft, the piston 30 and the operation rod 40 receiving the reaction force from the brake cylinder also move toward the spring chamber 46 to the position shown in 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 can be contracted to a position where one spring seat member 58 contacts the front surface of the other spring seat member 56, and the volume of the spring chamber 46 is made as small as possible. be able to.

  When the service brake is operated from the parking brake released state (in this embodiment, the brake pedal is depressed), compressed 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 to the brake cylinder side by the pressure. 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.

  By the way, when the parking brake is operated by the above-described use, the compression coil spring 54 repeatedly expands and contracts based on the operation. At this time, the small diameter portions 54a and 54b and the medium diameter portions 54c and 54e of the compression coil spring 54 are pressed toward the spring seat members 56 and 58 in proportion to the spring force of the spring. , 72 prevents contact with the spring seat members 56, 58.

  According to the spring brake actuator 20B according to the embodiment of the present invention, the resin is provided between the both end portions 54a and 54b of the compression coil spring 54 and the spring seat members 56 and 58 that respectively support the both end portions 54a and 54b. The compression coil spring 54 comes into contact with the resin sheet members 70 and 72 instead of the spring seat members 56 and 58 by interposing the elastic sheet members 70 and 72. Since the sheet members 70 and 72 have a small coefficient of friction with the compression coil spring 54, even if the compression coil spring 54 repeatedly expands and contracts, the compression coil spring 54 is in direct contact with the spring seat members 56 and 58. The coating applied to the outer surface of the compression coil spring 54 can be made difficult to peel or wear. As a result, since the bases of the compression coil spring 54 and the spring seat members 56 and 58 are not exposed, it is possible to prevent the compression coil spring 54 and the spring seat members 56 and 58 from being corroded. Thereby, the lifetime of the spring brake actuator 20B can be improved and the reliability can be improved.

In addition, when the bypass chamber 66 is formed in the spring chamber 46 so that the inside of the spring chamber 46 communicates with the atmosphere so that the inside of the spring chamber 46 does not become negative pressure, There is a risk that moisture may enter the spring chamber 46. However, since the coating of the compression coil spring 54 is difficult to peel or wear as described above, the compression coil spring 54 can be prevented from being corroded or rusted. Thereby, the lifetime of the spring brake actuator 20B can be improved and the reliability can be improved.
Furthermore, the occurrence of contact noise and sliding noise can be suppressed by interposing resin sheet members 70 and 72.

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 sectional drawing which shows the state from which the height of the slack part of the 2nd diaphragm with which a spring brake actuator is provided becomes the maximum. It is a front view which shows the compression coil spring with which a spring brake actuator is provided separately. It is a perspective view which shows the resin-made sheet members with which a spring brake actuator is equipped, Comprising: (a) is a resin-made sheet located in the 1st diaphragm side, (b) is a resin-made sheet located in the opposite side of (a). is there.

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 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 26 First diaphragm 28 Second diaphragm 30 Piston 35 Atmosphere 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 Small-diameter portion 54b Small-diameter portion 54c Medium-diameter portion 54d Large-diameter portion 54e Medium-diameter portion 56e 58 Spring seat member 56a Restraint portion 56b Boss portion 56c Key hole 56f Flat portion 56m Seat body 58a Cylindrical portion 58b Flange portion 58c Shaft end 66 Bypass pipe Road 70, 72 Sheet member 70a Open hole 70b, 72b Plane portion 70c Notch portion 72a Round hole

Claims (2)

A housing having a space inside and a diaphragm defining the space inside the housing into a spring chamber and a pressure chamber, and a coil spring for urging the diaphragm toward the pressure chamber are disposed inside the spring chamber. Spring brake actuator
A spring brake actuator, wherein a resin sheet member is interposed between both ends of the coil spring and spring seats respectively supporting the both ends.   The spring brake actuator according to claim 1, wherein the housing includes a passage through which the inside of the spring chamber communicates with the atmosphere.

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