JP2005291366A - Parking brake device - Google Patents

Abstract

An automatic parking brake state can be obtained with a simple structure without power consumption.
A parking brake state is obtained by a forward operation of a parking piston according to the action of a control fluid pressure for parking, and the forward state of the parking piston is mechanically locked by a lock mechanism. In addition, the lock piston 44 constituting a part of the lock mechanism 43 and the stopper 36 connected to the parking piston 33 are in contact with each other via the bearing 45 in order to maintain the forward operation state when the parking piston 33 is in the forward operation state. It is engaged.
[Selection] Figure 3

Description

  The present invention relates to a parking brake device, and more particularly to a parking brake device that obtains a parking brake state by the action of hydraulic pressure.

Such a parking brake device is already known from, for example, Patent Document 1 and Patent Document 2.
Japanese National Patent Publication No. 10-512947 JP 2000-504811 A

  By the way, in the said patent document 1, while a brake piston is divided | segmented into a front part and a rear brake piston, between the transmission member contact | abutted to the front end of a rear brake piston, and the obstruction board fixed to a front brake piston. A latch that can be engaged with an internal tooth engraved on the inner surface of the brake caliper behind the front brake piston with a spring contracted is engaged with the internal tooth when the transmission member is in contact with the front end of the rear brake piston. However, when the transmission member moves relatively forward from the front end of the rear brake piston, it is accommodated in the brake caliper so as to be disengaged from the inner teeth by a spring biasing force, and is transmitted to the rear brake piston. An auxiliary piston that can move the member in the axial direction relative to the rear brake piston is slidably fitted. However, internal teeth must be engraved on the inner surface of the brake caliper, and the latch is housed in the brake caliper while dividing the brake piston into the front and rear brake pistons. It becomes complicated.

  Further, in Patent Document 2, an adjustment nut is screwed onto an adjustment bolt whose front end is fixedly connected to a brake piston, and an electromagnet that exerts electromagnetic force that frictionally engages the adjustment nut with a casing is provided on the adjustment nut. The brake caliper is arranged behind the brake caliper. When the parking brake state is obtained, the brake piston is moved backward by frictionally engaging the adjusting nut with the casing by the electromagnet while the brake fluid pressure is applied to the brake piston. I try to prevent it. However, it is necessary to store the electromagnet in the brake caliper, which not only complicates the structure, but also requires that the energization state of the windings of the electromagnet be maintained in the parking brake state, resulting in an increase in power consumption.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a parking brake device that can obtain a parking brake state with a simple structure that does not involve power consumption.

  In order to achieve the above object, the present invention provides a parking piston that is slidably fitted to a casing so that a parking brake state can be obtained by a forward operation in accordance with the action of a control fluid pressure for parking on the back side. In order to mechanically lock the parking piston in the forward position, the locking piston is automatically locked according to the forward movement of the parking piston and unlocked according to the action of the parking release control hydraulic pressure. A lock mechanism provided in the casing, a fluid pressure generation source, and a fluid capable of obtaining the parking control fluid pressure and the parking release control fluid pressure by controlling the fluid pressure generated by the fluid pressure generation source Pressure control means, so that an urging force acting in one axial direction is applied at least when the parking piston moves forward. A part of the lock mechanism is provided that has an axis perpendicular to the axis of the parking piston and is slidably fitted to the casing and allows the parking release control pressure to act in the other axial direction. A lock piston and a stopper connected to the parking piston or the parking piston are brought into contact with and engaged via a bearing so as to maintain the forward operation state in the forward operation state of the parking piston. It is characterized by.

  According to the present invention, when the parking control hydraulic pressure is applied to the back side of the parking piston, the parking piston moves forward and the lock mechanism mechanically locks the advance position of the parking piston. When releasing the parking brake state, it is only necessary to apply the parking release control hydraulic pressure to the lock mechanism. In the parking brake state, the parking brake state is automatically set with a simple structure that does not involve power consumption. Can get to.

  Further, since the lock piston constituting a part of the lock mechanism and the stopper or the parking piston connected to the parking piston are brought into contact with and engaged with each other through the bearing in the forward operation state of the parking piston, the stopper or the parking piston In addition, it is possible to suppress wear, buckling, and the like due to a load acting on the lock piston from the parking piston side on the engagement portion, thereby improving durability.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on one embodiment of the present invention shown in the accompanying drawings.

  1 to 9 show an embodiment of the present invention, FIG. 1 is a front view of a drum brake, FIG. 2 is an enlarged sectional view taken along line 2-2 of FIG. 1, and FIG. 3 is a line 3-3 of FIG. FIG. 4 is a perspective view of the stopper and the lock piston, FIG. 6 is a diagram showing the configuration of the hydraulic circuit, and FIG. 7 corresponds to FIG. 2 in the parking brake state. 8 is a cross-sectional view taken along line 8-8 in FIG. 7, and FIG. 9 is a cross-sectional view taken along line 9-9 in FIG.

  First, in FIG. 1, a back plate 12 provided in a drum brake 11 as a brake mechanism dedicated to a parking brake is fixedly attached to the vehicle body side so as to cover an open end of a brake drum (not shown). One end of a pair of brake shoes 13, 13 having linings 14, 14 slidably contacting the brake drum and disposed in the brake drum is swingably supported on both ends of a strut 15 that can be expanded and contracted. Between the one ends of the shoes 13..., Springs 16 for urging the brake shoes 13. The other ends of the brake shoes 13 are detachably supported by an anchor 17 provided on the back plate 12 and are urged toward a side supported by the anchor 17 by a return spring 18. Further, notches 19 are respectively provided on the opposite surfaces of the brake shoes 13 on the other end side, and both ends of the strut 21 are engaged with the notches 19 so that one end of the strut 21 and one brake shoe are engaged. A spring 22 is contracted between 13.

  A parking operation lever 23 is disposed between the brake shoe 13 and the back plate 12 so as to partially overlap one of the brake shoes 13, and a parking drive means 25 is connected to one end of the operation lever 23. The other end portion of the parking operation lever 23 is engaged with one end of the strut 21 and is pivotably connected to the other end portion of the one brake shoe 13 via a pivot 24.

  Thus, when the parking operation lever 23 is rotated around the pivot 24 in the clockwise direction in FIG. 1 by the parking drive means 25, the other brake shoe 13 is pressed against the inner periphery of the brake drum via the strut 21. Due to the reaction, one brake shoe 13 is also pressed against the inner periphery of the brake drum, whereby a parking brake state by the drum brake 11 can be obtained.

  2 and 3 together, the parking drive means 25 includes a casing 26 fixed to the back plate 12 on one end side of the brake shoes 13. The casing 26 is integrally connected to a first tube portion 26a extending in a direction parallel to the struts 15 and the spring 16, and an intermediate portion of the first tube portion 26a extending in a direction orthogonal to the first tube portion 26a. The second cylinder part 26b is disposed on the inner surface side of the back plate 12, and the second cylinder part 26b extends outward through the back plate 12.

  A partition wall 27 is integrally provided at an axially intermediate portion of the first tube portion 26a with both ends open, and a first sliding hole is formed in the first tube portion 26a on the front side (left side in FIG. 3) of the partition wall 27. 28, a guide hole 29 coaxial with the first sliding hole 28 is provided in the first cylindrical portion 26a on the rear side (right side in FIG. 3) of the partition wall 27, and the front end of the first sliding hole 28 is provided. The lid member 30 that closes is screwed into the first tube portion 26a.

  The second cylindrical portion 26 b is provided with a second sliding hole 31 that is continuous to the guide hole 29 at a right angle. The second sliding hole 31 has a small-diameter hole portion 31 a with one end connected to the guide hole 29. And a large-diameter hole 31b having one end coaxially connected to the other end of the small-diameter hole 31a and having a diameter larger than that of the small-diameter hole 31a, and is formed between the small-diameter hole 31a and the large-diameter hole 31b. An annular step portion 31c facing the opposite side of the guide hole 29 is formed, and a lid member 32 that closes the other end of the large diameter hole portion 31b is screwed to the outer end of the second cylindrical portion 26b.

  The first sliding hole 28 of the casing 26 is slidably fitted with a parking piston 33 that can obtain a parking brake state by a forward operation according to the action of the control hydraulic pressure for parking on the back side. An annular seal member 40 is attached to the outer periphery of the parking piston 33. A parking control fluid pressure chamber 34 is formed between the rear surface of the parking piston 33 and the partition wall 27 in the first cylindrical portion 26a of the casing 26 so that the parking control fluid pressure can be applied.

  The parking piston 33 is connected to one end portion of the parking operation lever 23 in the drum brake 11 via a connecting means 35, and a traction force acting on the connecting means 35 according to the forward operation of the parking piston 33 is the parking operation. As a result, the parking operation lever 23 is rotated to the side on which the drum brake 11 is parked.

  Thus, the connecting means 35 is a rod that passes through the partition wall 27 through the annular seal member 41 in a liquid-tight and slidable manner and is coaxially and integrally connected to the center of the rear end of the parking piston 33. 33a, a stopper 36 connected to the rod 33a and slidably fitted in the guide hole 29, and a connecting rod 37 connecting the stopper 36 and the parking operation lever 23, and is opposite to the partition wall 27. On the side, a stopper ring 42 is attached to the end of the guide hole 29 to prevent the stopper 36 from coming off the guide hole 29.

  Referring also to FIG. 4, one end portion of the parking operation lever 23 is bent in a substantially U shape so as to form a slit 38, and the end portion of the connecting rod 37 inserted through the slit 38. In addition, an enlarged engagement portion 37 a that contacts and engages with one end portion of the parking operation lever 23 is provided. In addition, the contact surface 39 provided on the parking operation lever 23 so as to contact and engage the enlarged engagement portion 37a has an arcuate shape, and acts on the parking operation lever 23 as the parking piston 33 moves forward. The tangent of the contact surface 39 at the contact point of the enlarged engagement portion 37a when the traction force is maximized is not only perpendicular to the traction force acting direction from the connection rod 37 to the parking operation lever 23, but also the connection rod. In the entire stroke area 37, the tangent line at the contact point of the enlarged engagement portion 37a is formed to be perpendicular to the direction of the traction force.

  In addition, the outer surface shape of at least the portion of the enlarged engaging portion 37 a that contacts the contact surface 39 is formed into a curved surface that is convex toward the contact surface 39.

  Further, in the casing 26, the parking piston 33 is automatically locked in accordance with the forward operation of the parking piston 33 so as to mechanically lock the parking piston 33 in the forward position, and in response to the operation of the parking release control hydraulic pressure. A lock mechanism 43 that operates to unlock is provided.

  The lock mechanism 43 has an axis perpendicular to the axis of the parking piston 33 and is slidable on the casing 26 while allowing an urging force to act in one axial direction when the parking piston 33 moves forward. It is an intermediate member of the lock piston 44 that is fitted and allows the control pressure for parking release to act in the other axial direction, and the connecting means 35 that connects between the parking piston 33 and the parking operation lever 23. The lock pistons 45 and 45 mounted on both sides of the stopper 36 and the outer rings 45a of the bearings 45 and 45 are abutted and engaged from behind to mechanically lock the forward operation position of the parking piston 33. And a pair of lock portions 46 and 46 provided at one axial end of 44.

  Referring also to FIG. 5, the stopper 36 is formed to have a substantially rectangular cross-sectional shape in which the thickness in the direction orthogonal to the axis of the second sliding hole 31 and the guide hole 29 is reduced, The bearings 45 are mounted on support bosses 47 projecting from both sides of the stopper 36.

  The lock piston 44 is slidably fitted in the second sliding hole 31 disposed on the rear side of the parking piston 33, and slides in the small diameter hole portion 31a of the second sliding hole 31. A small-diameter portion 44a that can be fitted and an annular step portion 44c that faces the step portion 31c of the second sliding hole 31 are formed between the rear portion of the small-diameter portion 44a and coaxially connected to the small-diameter portion 44a. A large-diameter portion 44b slidably fitted in the large-diameter hole portion 31b of the second sliding hole 31 is integrally provided.

  Between the lock piston 44 and the lid member 32, for example, a pair of springs 48, 48 arranged in parallel are contracted to spring-bias the lock piston 44 toward one axial side, that is, the stopper 36 side. In addition, a parking release control hydraulic pressure is applied between the lock piston 44 and the casing 26 between the stepped portion 44c of the lock piston 44 and the stepped portion 31c of the second sliding hole 31 to bias the lock piston 44 to the other side in the axial direction. An annular parking release control hydraulic pressure chamber 49 is formed, and the pressure receiving area of the lock piston 44 facing the parking release control hydraulic pressure chamber 49 is greater than the pressure receiving area of the parking piston 33 facing the parking control hydraulic pressure chamber 34. Is also set larger.

  Further, on the outer periphery of the small diameter portion 44a and the large diameter portion 44b of the lock piston 44, the parking release control hydraulic pressure chambers 49 are sealed from both sides in the axial direction, and the small diameter hole portion 31a and the large diameter hole portion of the second sliding hole 31 are sealed. Annular seal members 50 and 51 slidably contacting 31b are mounted.

  A pair of the lock portions 46, 46 are disposed on the small diameter portion 44 a on one end side of the lock piston 44, and the outer rings of the bearings 45, 45 straddle the stopper 36 at the intermediate portion of the connecting means 35 when the parking piston 33 is advanced. .. Are connected so as to engage with 45a. Moreover, the outer peripheral surface of the lock portion 46 is formed in a taper shape with the tip side narrowed so that the second slide hole 31 can be inserted into the guide hole 29 having a smaller diameter than the small diameter hole portion 31a.

  Further, the lock portion 46 is formed with an engagement surface 46a that can contact and engage with the outer ring 45a of the bearing 45 from the rear side, and this engagement surface 46a is formed in one axial direction of the lock piston 44. As it goes, the parking piston 33 is inclined so as to be in the rearward position in the axial direction.

  In FIG. 6, the parking control hydraulic pressure that acts on the parking control hydraulic chamber 34 and the parking release control hydraulic pressure that acts on the parking release control hydraulic chamber 49 are the hydraulic pressure generated by the hydraulic pressure source 55. The fluid pressure control means 56 is obtained by controlling the parking control fluid pressure chamber 34 to the fluid pressure generation source 55 and the reservoir 57, and for parking. A state in which the first control valve 58 capable of switching the hydraulic pressure lock state of the control hydraulic pressure chamber 34 and the parking release control hydraulic pressure chamber 49 are selectively communicated to the hydraulic pressure generation source 55 and the reservoir 57 and the parking release. And a second control valve 59 capable of switching the hydraulic pressure lock state of the control hydraulic pressure chamber 49.

  When the parking brake state is obtained, the parking control fluid pressure chamber 34 is acted on by the parking control fluid pressure chamber 34 and the parking release control fluid pressure chamber 49 is actuated by the fluid pressure acting on the parking piston control fluid pressure chamber 34. The parking piston 33 is moved forward while suppressing the operation of. Next, when the hydraulic pressure in the parking release control hydraulic pressure chamber 49 is released, the lock piston 44 is actuated in one axial direction by the spring force of the springs 48... And the lock mechanism 43 is moved according to the advance of the parking piston 33 and the lock piston 44. The lock operates.

  That is, as shown in FIG. 7 to FIG. 9, the engagement surface 46 a formed on the lock portion 46 at one end of the lock piston 44 on the outer ring 45 a of the bearing 45 mounted on the stopper 36 that has moved forward together with the parking piston 33. ... are brought into contact with and engaged from behind, and the forward operation state of the parking piston 33 is mechanically locked. However, when the operation of the lock piston 44 in one axial direction is completed, the residual pressure in the parking control hydraulic chamber 34 is released.

  When the parking piston 33 moves forward as described above, the drum brake 11 is parked by the rotation of the parking operation lever 23, and the parking brake state is maintained by locking the forward movement state of the parking piston 33. Moreover, since the force for operating the brake shoes 13 for the parking brake in the drum brake 11 is transmitted to the brake shoes 13 through the parking operation lever 23, the parking drive means 25 is controlled by the lever ratio of the parking operation lever 23. The liquid pressure to be exerted is relatively small.

  When releasing the parking brake state, the hydraulic pressure in the parking control fluid pressure chamber 34 and the parking release control fluid pressure chamber 49 are simultaneously increased. In the pressure increasing process, first, the spring force of the springs 48 is larger than the spring force. When the hydraulic pressure acts on the lock piston 44, the lock piston 44 moves to the other side in the axial direction, thereby releasing the lock state of the lock mechanism 43. Therefore, the parking piston is controlled by the hydraulic pressure in the parking control hydraulic pressure chamber 34. 33 moves backward. Thus, when the lock mechanism 43 is unlocked, the parking release control hydraulic pressure chamber 49 is held in a hydraulic pressure locked state, and the lock portion 46 of the lock piston 44 avoids contact with the bearing 45 of the stopper 36. It has moved to the position where

  Next, the operation of this embodiment will be described. When the drum brake 11 is operated as a parking brake, the parking control hydraulic pressure is applied to the parking control hydraulic pressure chamber 34 facing the back side of the parking piston 33 of the parking drive means 25. By operating the parking piston 33 forward, it is possible to brake the drum brake 11 to obtain a parking brake state, and the parking operation state due to the forward operation of the parking piston 33 is determined by the lock mechanism 43. Since it is mechanically locked, the parking brake state can be obtained automatically, and when releasing the parking brake state, the parking release control hydraulic pressure should be applied to the lock mechanism 43. With consumption In no simple structure can be obtained parking brake state automatically.

  Further, the lock mechanism 43 has an axis perpendicular to the axis of the parking piston 33 and is slidably fitted to the casing 26 so that an urging force in one axial direction acts when the parking piston 33 moves forward. And a lock piston 44 capable of causing the parking release control pressure to act in the other axial direction, a bearing 45 provided on a stopper 36 connected to the parking piston 33, and an outer ring of the bearing 45 ... 45a... Having a lock portion 46 provided at one end in the axial direction of the lock piston 44 and having an engagement surface 46a for mechanically locking the forward operation position of the parking piston 33 by engaging with the rear 45a. The engaging surface 46a... Of the parking piston 33 moves toward the one axial direction of the lock piston 44. It is inclined such that the rearward position.

  Accordingly, it is possible to mechanically lock the forward operation position of the parking piston 33 in response to a change in the forward movement amount from the backward limit of the parking piston 33 in the parking brake state, and the dimensional tolerance, assembly error or brake It is possible to cope with a change in the stroke amount of the parking piston 33 according to the wear of the linings 14 in the shoes 13.

  Further, since the lock piston 44 and the stopper 36 are brought into contact with and engaged with each other via the pair of bearings 45 in the forward operation state of the parking piston 33, the stopper 36 and the lock piston 44 are brought into contact with and engaged with the parking portion. Wear and buckling due to a load acting from the piston 33 side can be suppressed and durability can be improved. In particular, when the lock is released, the lock piston 44 moves to the other side in the axial direction with the engagement surface 46a being in contact with the outer ring 45a of the bearing 45 while the load is applied from the parking piston 33 side. In this case, since the outer rings 45a can be driven and rotated by the engagement surfaces 46a, wear and buckling can be more effectively suppressed.

  In addition, the stopper 36 provided with the bearings 45 is disposed in the middle of the connecting means 35 connecting the parking piston 33 and the parking operation lever 23, and the lock portions 46 and 46 straddle the stopper 36. Since it is provided at one end of the lock piston 44, the forward drive force of the parking piston 33 is transmitted to the parking operation lever 23 of the drum brake 11 via the connecting means 35, and the lock mechanism 43 is made compact. Simplification can be achieved.

  Further, an enlarged engaging portion 37a provided at an end of the connecting rod 37 which is a part of the connecting means 35 is brought into contact with and engaged with one end of the parking operation lever 23. An arc-shaped contact surface 39 provided on the parking operation lever 23 for contact and engagement is enlarged when the traction force acting on the parking operation lever 23 is maximized as the parking piston 33 moves forward. The tangent of the contact surface 39 at the contact point of the engaging portion 37a is not only perpendicular to the direction of the traction force acting from the connecting rod 37 to the parking operation lever 23, but also expanded in the entire stroke region of the connecting rod 37. The tangent line at the contact point of the portion 37a is formed so as to be perpendicular to the traction force acting direction.

  Therefore, when the traction force acting on the parking operation lever 23 is maximized, it is possible not only to suppress the twisting between the connecting rod 37 and the parking operation lever 23 and to improve the durability, but also to improve the durability of the connecting rod 37. It is possible to suppress the occurrence of twisting between the connecting rod 37 and the parking operation lever 23 in the entire stroke region, and to further improve the durability.

  Further, since the outer surface shape of at least the portion of the enlarged engaging portion 37a that contacts the contact surface 39 is formed in a curved shape that is convex toward the contact surface 39, the space between the connecting rod 37 and the parking operation lever 23 is increased. The occurrence of twisting can be more effectively suppressed, and the contact area between the parking operation lever 23 and the enlarged engagement portion 37a can be made relatively large to reduce stress.

  Moreover, since the connecting rod 37 can be engaged with and connected to the parking operation lever 23 by inserting the connection rod 37 of the slit 38 provided in the parking operation lever 23, the assembling property is also good.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. It is.

  For example, bearings 45 may be provided on the lock piston 44 side.

It is a front view of a drum brake. FIG. 2 is an enlarged sectional view taken along line 2-2 of FIG. FIG. 3 is a sectional view taken along line 3-3 in FIG. 2. FIG. 4 is a view taken in the direction of arrow 4 in FIG. 3. It is a perspective view of a stopper and a lock piston. It is a figure which shows the structure of a hydraulic circuit. It is sectional drawing corresponding to FIG. 2 in a parking brake state. FIG. 8 is a cross-sectional view taken along line 8-8 in FIG. 7. FIG. 9 is a sectional view taken along line 9-9 in FIG. 8.

Explanation of symbols

26 ... Casing 33 ... Parking piston 36 ... Stopper 43 ... Lock mechanism 45 ... Bearing 45a ... Outer ring 52 ... Supporting part 55 ... Fluid pressure source 56 ... Fluid pressure control means

Claims (1)

  A parking piston (33) that is slidably fitted to the casing (26) so as to be able to obtain a parking brake state by a forward operation according to the action of the control fluid pressure for parking on the back side, and the parking piston ( 33) is automatically locked according to the forward movement of the parking piston (33) so as to be mechanically locked at the forward position, and unlocked according to the action of the parking release control hydraulic pressure. The lock mechanism (43) provided in the casing (26), the hydraulic pressure generation source (55), and the generated hydraulic pressure of the hydraulic pressure generation source (55) are controlled to control the parking control hydraulic pressure and the parking release. Hydraulic pressure control means (56) capable of obtaining a control hydraulic pressure for the vehicle, and at least when the parking piston (33) is moved forward, the shaft A parking release control pressure having an axis perpendicular to the axis of the parking piston (33) and slidably fitted to the casing (26) while allowing an urging force to act in one direction. A locking piston (44) that constitutes a part of the locking mechanism (43) and a stopper (36) connected to the parking piston (33) or the parking piston. (33) is abutted and engaged via a bearing (45) in order to maintain the forward operation state in the forward operation state of the parking piston (33).

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