JP2005291374A - 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 mechanism 43 is provided on a member 33 that operates integrally with the parking piston 30 and is axially connected to the ratchet teeth 44. The lock mechanism 43 is rotationally biased in a direction to engage with the ratchet teeth 44 and is used for releasing the parking. There is provided an engaging claw 45 that is rotatably supported on the casing 26 so as to rotate to the side for releasing the engagement with the ratchet teeth 44 according to the action of the control hydraulic pressure.
[Selection] Figure 2

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 slidably fitted to a casing so as to obtain a parking brake state in accordance with a forward operation in accordance with an action of a control fluid pressure for parking on the back side. In order to mechanically lock the piston and the parking piston in the forward position, the 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. It is possible to obtain the parking control fluid pressure and the parking release control fluid pressure by controlling the lock mechanism provided in the casing, the fluid pressure generation source, and the fluid pressure generated by the fluid pressure generation source. The locking mechanism is provided on a member that operates integrally with the parking piston or the parking piston. The ratchet teeth that are continuous in the axial direction are rotated and biased in a direction to engage with the ratchet teeth, and the ratchet teeth are rotated toward the side that releases the engagement with the ratchet teeth according to the action of the parking release control hydraulic pressure. And an engaging claw rotatably supported on the casing so as to move.

  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.

  In addition, the lock mechanism is a member that operates integrally with the parking piston or a ratchet tooth that is provided on the parking piston and that is continuous in the axial direction, and is urged to rotate in a direction to engage with the ratchet tooth and release the parking And an engaging claw that is rotatably supported on the casing so as to rotate to the side for releasing the engagement with the ratchet teeth according to the action of the control hydraulic pressure. The configuration can be simplified.

  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 3 show an embodiment of the present invention, FIG. 1 is a front view of a drum brake, FIG. 2 is a longitudinal sectional view of a parking drive means, and FIG. 3 is a view taken in the direction of arrow 3 in FIG. .

  First, in FIG. 1, a back plate 12 provided in a drum brake 11 that is 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.

  Referring also to FIG. 2, the parking driving means 25 includes a casing 26 fixed to the back plate 12 at one end side of the brake shoes 13. The casing 26 is provided with a first sliding hole 27 whose one end is closed by an end wall 26a.

  The first sliding hole 27 of the casing 26 is slidably fitted with a parking piston 30 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 31 is attached to the outer periphery of the parking piston 30. A parking control fluid pressure chamber 32 is formed in the casing 26 between the rear surface of the parking piston 30 and the end wall 26a.

  A rod 33 that is an interlocking member that operates integrally with the parking piston 30 is press-fitted into the parking piston 30 so as to penetrate the central portion of the parking piston 30, and one end side of the rod 33 is annular. The end wall 26a is slidably penetrated through the sealing member 34. In addition, the rod 33 includes a small-diameter connecting shaft portion 33 a on one end side, and the small-diameter connecting shaft portion 33 a is connected to one end portion of the parking operation lever 23 in the drum brake 11. Accordingly, a traction force corresponding to the forward operation of the parking piston 30 and the rod 33 is input to the parking operation lever 23, whereby the parking operation lever 23 rotates to the side where the parking brake is operated.

  Referring also to FIG. 3, one end portion of the parking operation lever 23 is bent into a substantially U shape so as to form a slit 35, and the small-diameter connecting shaft portion 33 a inserted through the slit 35 has An engagement member 36 that contacts and engages with one end of the parking operation lever 23 is fixed to the end. In addition, the contact surface 37 provided on the parking operation lever 23 to contact and engage the engagement member 36 is arcuate, and the traction force acting on the parking operation lever 23 as the parking piston 30 moves forward. The tangent of the abutment surface 37 at the contact point of the engagement member 36 when the maximum is not only perpendicular to the direction of the traction force acting on the parking operation lever 23 from the rod 33, that is, the small diameter connecting shaft portion 33a. The tangent line at the contact point of the engagement member 36 is formed so as to be perpendicular to the traction force acting direction in the entire stroke region of the rod 33.

  In addition, the outer surface shape of at least the portion of the engaging member 36 that contacts the contact surface 37 is a curved surface that is convex toward the contact surface 37.

  Further, in the casing 26, the parking piston 30 is automatically locked in accordance with the forward operation of the parking piston 30 so as to mechanically lock the parking piston 30 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 is provided on the outer periphery of the other end of the rod 33 that operates integrally with the parking piston 30, and is urged to rotate in a direction to engage with the ratchet teeth 44. And an engaging claw 45 that is rotatably supported by the casing 26 so as to rotate to the side for releasing the engagement with the ratchet teeth 44 in accordance with the action of the parking release control hydraulic pressure.

  The casing 26 is provided with a bottomed second sliding hole 46 having one end closed at a portion corresponding to an intermediate portion of the first sliding hole 27 in parallel with the first sliding hole 27. The other end opening of the moving hole 46 is liquid-tightly closed by a lid member 47. Further, a support hole 48 connecting the second slide hole 46 and the first slide hole 27 near the one end closed portion of the second slide hole 46, and an inner side of the second slide hole 46 on the opposite side of the support hole 48. The casing 26 is provided with a restriction hole 49 that opens at the end and opens the outer end to the outer surface of the casing 26.

  An engaging claw 45 capable of engaging one end with the ratchet teeth 44 is inserted into the support hole 48 and the restricting hole 49 so that the other end protrudes outward from the casing 26. An engaging claw 45 is rotatably supported on the casing 26 via a support shaft 50 having an axis perpendicular to the plane including the axis of the moving holes 27 and 46 and crossing the support hole 48. The rotation range is restricted to a range in which the other end side of the engagement claw 45 contacts the inner surface of the restriction hole 49.

  Further, a spring 51 is provided between the one end closed portion of the second sliding hole 46 and the engaging claw 45, and the engaging claw 45 is elastically moved in a direction to engage with the ratchet teeth 44 by the spring force of the spring 51. It is energized.

  In addition, the control piston 52 that forms the parking release control hydraulic pressure chamber 53 between the engagement claw 45 and the lid member 47 in the second slide hole 46 on the opposite side of the spring 51 is slidable. Mated. The control piston 52 is in contact with the engaging claw 45 from the side opposite to the spring 51, and overcomes the spring force of the spring 51 so that the engaging claw 45 is disengaged from the ratchet teeth 44. Can be pressed.

  The parking control fluid pressure acting on the parking control fluid pressure chamber 32 and the parking release control fluid pressure acting on the parking release control fluid pressure chamber 53 are the fluid pressure control means 56 that generates the fluid pressure generated by the fluid pressure source 55. This hydraulic pressure control means 56 includes a first control valve 58 for selectively communicating the parking control hydraulic pressure chamber 32 with the hydraulic pressure generation source 55 and the reservoir 57, and a parking control. The release control hydraulic pressure chamber 53 includes a second control valve 59 that selectively communicates with the hydraulic pressure generation source 55 and the reservoir 57.

  When the parking brake state is obtained, the parking control hydraulic pressure is applied to the parking control hydraulic chamber 32 with the hydraulic pressure in the parking release control hydraulic chamber 53 released. As a result, the parking piston 30 and the rod 33 move forward with the ratchet teeth 44 so as to raise the engaging claws 45, and the parking operation lever 23 is driven to rotate to obtain a parking brake state by the drum brake 11. When the engagement piston 45 engages with the ratchet teeth 44 while the parking piston 3 and the rod 33 are stationary, the forward operation state of the parking piston 30 is mechanically locked. Even if the hydraulic pressure in the control hydraulic chamber 32 is released, it is maintained.

  In releasing the parking brake state of the drum brake 11, first, the hydraulic pressure from the hydraulic pressure generating source 55 is applied to the parking control hydraulic pressure chamber 53. Then, the parking piston 30 and the rod 33 move forward, and the force applied to the engaging claw 45 from the ratchet teeth 44 is reduced. Next, the hydraulic pressure from the hydraulic pressure generating source 55 is supplied to the parking release control hydraulic pressure chamber 53. When operated, the engaging claw 45 is rotated to a position where it is retracted to a position where the engagement with the ratchet teeth 44 is released. Accordingly, when the hydraulic pressure in the parking control hydraulic pressure chamber 53 is released, the parking operation lever 23 returns to the original position while the parking piston 30 and the rod 33 are retracted by the spring force of the return spring 18 provided in the drum brake 11. Therefore, by releasing the hydraulic pressure in the parking release control hydraulic pressure chamber 53, the state before the parking brake state is obtained is restored.

  By the way, the parking drive means 25 is provided with an adjusting mechanism 60, and the adjusting mechanism 60 includes a ring-shaped spring receiving member 61 fixed to the other end portion of the first sliding hole 27 by screwing or the like, An adjustment piston 62 provided in the center with a through-hole 63 that is slidably fitted to the spring receiving member 61 so as to face from the inside and through which the other end of the rod 33 can be moved in the axial direction. And an adjustment engagement claw 64 attached to the adjustment piston 62 so as to be able to engage with the ratchet teeth 44 on the outer periphery of the rod 33 at a portion protruding outward from the adjustment piston 62, and the adjustment An adjustment spring 65 is provided between the spring receiving member 61 and the adjustment engagement claw 64 so as to urge the engagement claw 64 to engage with the ratchet teeth 44.

  In such an adjusting mechanism 60, in the non-parking brake state, the adjustment piston 62 is located at a distance L from the spring receiving member 61. In this state, the parking piston 30 is moved forward to obtain the parking brake state. And the adjustment engagement claw 64 is engaged with the ratchet teeth 44 of the rod 33 that moves forward integrally with the parking piston 30, so that the adjustment piston 62 is moved closer to the spring receiving member 61. Move forward a distance less than L. However, if the amount of forward movement of the parking piston 30 increases due to wear of the linings 14 of the brake shoes 13 in the drum brake 11, the spring force of the adjustment spring 65 biasing the adjustment claw 64 is overcome. Thus, the ratchet teeth 44, that is, the rod 33 moves forward so as to push away the adjustment engaging claws 64, and the adjustment engaging claws 64 engage with the ratchet teeth 44 closer to the parking piston 30. become.

  Therefore, regardless of the amount of wear of the linings 14..., The forward stroke of the parking piston 30 when the parking brake is operated is maintained almost constant by the adjusting mechanism 60.

  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 32 facing the back side of the parking piston 30 of the parking drive means 25. By operating the parking piston 30 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 30 is determined by the lock mechanism 43. Since it is mechanically locked, the parking brake state can be automatically obtained, and in the parking brake state, the parking brake state can be automatically obtained with a simple structure without power consumption.

The lock mechanism 43 is provided on the rod 33 that operates integrally with the parking piston 30 and is axially connected to the ratchet teeth 44. The lock mechanism 43 is rotationally biased in a direction to engage with the ratchet teeth 44 and is used for releasing the parking. The lock mechanism 43 includes an engagement claw 45 that is rotatably supported on the casing 26 so as to rotate to the side of releasing the engagement with the ratchet teeth 44 according to the action of the control hydraulic pressure. Further, the engagement member 36 fixed to the end of the small-diameter connecting shaft 33a provided on one end of the rod 33 is brought into contact with and engaged with one end of the parking operation lever 23. However, the arc-shaped abutment surface 37 provided on the parking operation lever 23 in order to abut and engage the engagement member 36 is accompanied by the forward movement of the parking piston 30. Thus, the tangent of the contact surface 37 at the contact point of the engagement member 36 when the traction force acting on the parking operation lever 23 is maximized is from the rod 33, that is, the small diameter connecting shaft portion 33a to the parking operation lever 23. In addition to being perpendicular to the traction force acting direction, the tangent line at the contact point of the engagement member 36 is formed to be perpendicular to the traction force acting direction in the entire stroke region of the rod 33.

  Accordingly, when the traction force acting on the parking operation lever 23 is maximized, not only can the occurrence of a twist between the rod 33 and the parking operation lever 23 be suppressed, and the durability can be improved, but also the entire stroke of the rod 33 can be achieved. It is possible to suppress the occurrence of a twist between the rod 33 and the parking operation lever 23 in the region, and to further improve the durability.

  In addition, since the outer surface shape of at least the portion of the engaging member 36 that contacts the contact surface 37 is formed in a curved surface that is convex toward the contact surface 37, there is a twist between the rod 33 and the parking operation lever 23. Occurrence can be suppressed more effectively, and the contact area between the parking operation lever 23 and the engagement member 36 can be made relatively large to reduce stress.

  Moreover, since the rod 33 can be engaged with and connected to the parking operation lever 23 by inserting the small-diameter connection shaft portion 33a through the slit 35 provided in the parking operation lever 23, the assemblability is 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.

It is a front view of a drum brake. It is a longitudinal cross-sectional view of a parking drive means. FIG. 3 is a view taken in the direction of arrow 3 in FIG. 2.

Explanation of symbols

26 ... casing 30 ... parking piston 33 ... rod 43 as interlocking member ... lock mechanism 44 ... ratchet teeth 45 ... engagement claw 55 ... hydraulic pressure source 56 ...・ Hydraulic pressure control means

Claims (1)

  A parking piston (30) slidably fitted to the casing (26) so as to obtain a parking brake state in accordance with a forward operation according to the action of the control fluid pressure for parking on the back side; and the parking piston (30) is automatically locked according to the forward movement of the parking piston (30) so as to be mechanically locked at the forward position, and unlocked according to the action of the parking release control hydraulic pressure. A lock mechanism (43) provided in the casing (26), a hydraulic pressure generation source (55), and a generated hydraulic pressure of the hydraulic pressure generation source (55) to control the parking control hydraulic pressure and the parking Hydraulic pressure control means (56) capable of obtaining the release control hydraulic pressure, and the lock mechanism (43) is integrated with the parking piston (30). A ratchet tooth (44) provided in the operating interlocking member (33) or the parking piston (30) and continuing in the axial direction, and is urged to rotate in a direction to engage with the ratchet tooth (444). An engagement claw (45) rotatably supported on the casing (26) so as to be able to turn to the side for releasing the engagement with the ratchet teeth (44) according to the action of the release control hydraulic pressure. And a parking brake device.

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