JP2005282615A - Parking brake unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain an automatic parking brake state with simple structure without consuming electric power. <P>SOLUTION: The parking brake state of a wheel brake 2A is obtained by advance actuation of a parking piston 44 that is faced with a control hydraulic chamber 47 for parking on the back side to be slidably engaged with a casing 23. The advanced state of the parking piston 44 is mechanically locked by a lock mechanism 31. An insertion shaft 59 to compose part of the lock mechanism 31 comprises a small diameter shaft part 59a on the front side and a large diameter shaft part 59b on the rear side, which are coaxially and integrally linked through a taper part 59c that varies contact positions of respective lock elements 58 in accordance with advance move of the lock piston 59 from the small diameter shaft part 59a to the large diameter shaft part 59b. The angle of the taper part 59c to the axial line of the insertion shaft 59 is set to be 20-60deg. <P>COPYRIGHT: (C)2006,JPO&NCIPI

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 locking a brake piston in a hydraulic pressure operating state.

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 behind the parking piston, a hydraulic pressure generation source, and a control hydraulic pressure for parking and a control hydraulic pressure for parking release by controlling the generated hydraulic pressure of the hydraulic pressure generation source And a hydraulic pressure control means that makes it possible to obtain at least a forward operation of the parking piston. Sometimes it is possible to apply a biasing force toward the front side so that the casing is slidably fitted to the casing on the rear side of the parking piston and to allow the control pressure for parking release to be applied to the rear side. The lock piston, the cylindrical holding cylinder integrally and coaxially connected to the rear portion of the parking piston, and the holding cylinder are held at a plurality of circumferential positions so that the holding cylinder can be moved in the radial direction. A locking element that is inserted into the holding cylinder so as to be movable in the axial direction so as to come into contact with the locking elements from the inner side of the holding cylinder and sandwich the locking elements with the inner surface of the casing. And an insertion shaft integrally connected to the front end of the lock piston, and the insertion shaft moves the lock elements in the radial direction when the parking piston is in the retreat limit. A small-diameter shaft portion on the front side that is disposed on the inner side, and each lock element is disposed on the radially outer side when the lock piston moves forward to a forward position as the parking piston moves forward from the retreat limit. A large-diameter shaft portion to be connected is coaxially and integrally connected via a tapered portion that changes the contact position of each lock element from the small-diameter shaft portion to the large-diameter shaft portion in accordance with the forward movement of the lock piston. The angle formed by the taper portion with respect to the axis of the insertion shaft is set to 20 to 60 degrees, and the inner surface of the casing has the lock piston in the forward position and the radial direction at the large-diameter shaft portion. A restriction step portion that can come into contact with each of the locking elements pushed upward from the rear side is provided.

  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.

  The lock mechanism is slidably fitted to the casing on the rear side of the parking piston so that a forward biasing force acts when the parking piston moves forward, and the parking release control hydraulic pressure is A lock piston adapted to act toward the rear, a cylindrical holding cylinder integrally and coaxially connected to the rear portion of the parking piston, and a lock element held at a plurality of locations in the circumferential direction of the holding cylinder, An insertion shaft integrally connected to the front end of the lock piston so as to contact each lock element from the inner side of the holding cylinder and sandwich each lock element with the inner surface of the casing. Each large-diameter shaft portion and small-diameter shaft portion are coaxially and integrally connected via a taper portion, and each lock is pushed up radially outward by the large-diameter shaft portion on the inner surface of the casing. Since the regulation step part that can come into contact with the element from the rear side is provided, the lock piston moves forward during the forward movement of the parking piston, so that each lock element has a large diameter smoothly from the small diameter shaft part of the insertion shaft to the taper part. It is pushed up by being guided to the shaft side, and each lock element is controlled to move backward in the restricting step part and restricted to move inward in the radial direction by the large diameter shaft part. Can be maintained. Moreover, the parking brake state can be released by applying the control fluid pressure for parking release to the lock piston to retract the lock piston.

  In addition, since the angle formed by the taper portion with respect to the axis of the insertion shaft is set to 20 to 60 degrees, the lock piston, that is, each lock element is moved forward when the insertion shaft is advanced, while avoiding the stroke of the insertion shaft from becoming dark. It can be pushed up smoothly. That is, when the angle is less than 20 degrees, each lock element can be pushed up smoothly, but the stroke of the insertion shaft becomes too large. When the angle exceeds 60 degrees, the lock piston moves forward. Accordingly, the component force for pushing up each locking element is insufficient, and it becomes difficult to push up each locking element smoothly.

  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 7 show an embodiment of the present invention. FIG. 1 is a hydraulic circuit diagram of a vehicle brake device, FIG. 2 is a longitudinal sectional view of a left front wheel brake at the time of non-parking brake, and FIG. 2 is a view taken in the direction of arrow 3 in FIG. 2, FIG. 4 is an enlarged view of the main part of FIG. 2, FIG. 5 is a longitudinal sectional view corresponding to FIG. 2 in the parking brake state, and FIG. FIG. 7 is a sectional view showing a state in which the tool is connected to the lock piston.

  First, in FIG. 1, the tandem master cylinder M is provided with first and second output ports 1A and 1B for generating brake fluid pressure in accordance with the pedaling force applied to the brake pedal 4 by the vehicle driver, and the first output. The port 1A is connected to the first output hydraulic pressure path 3A, and the second output port 1B is connected to the second output hydraulic pressure path 3B.

  The first output hydraulic pressure path 3A is connected to the first hydraulic pressure path 20A via a cut valve 17A that is a normally open type electromagnetic valve, and the second output hydraulic pressure path 3B is a cut valve that is a normally open type electromagnetic valve. It is connected to the second hydraulic pressure path 20B via 17B.

  The first hydraulic path 20A is connected to the left front wheel wheel brake 2A, which is a disc brake with a parking brake mechanism, via an inlet valve 6A, which is a normally open solenoid valve, and is an inlet valve, which is a normally open solenoid valve. 6B is connected to a wheel brake 2B for the right rear wheel, which is a disc brake. The second hydraulic pressure path 20B is connected to a right front wheel wheel brake 2C, which is a disc brake with a parking brake mechanism, via an inlet valve 6C, which is a normally open solenoid valve, and is an inlet, which is a normally open solenoid valve. It is connected to a wheel brake 2D for the left rear wheel, which is a disc brake, via a valve 6D. Further, check valves 7A to 7D are connected in parallel to the inlet valves 6A to 6D, respectively.

  Outlet valves 9A and 9B, which are normally closed solenoid valves, are provided between the first reservoir 8A corresponding to the first hydraulic pressure path 20A and the left front wheel brake 2A and the right rear wheel brake 2B, respectively. Outlet valves 9C and 9D, which are normally closed solenoid valves, are provided between the second reservoir 8B corresponding to the second hydraulic pressure path 20B and the right front wheel brake 2C and the left rear wheel brake 2D, respectively.

  The first and second reservoirs 8A, 8B allow the brake fluid to flow to the pump 10A, 10B side on the suction side of the first and second pumps 10A, 10B driven by the common electric motor 11. The directional valves 19A and 19B are connected. The first and second output hydraulic pressure paths 3A and 3B are connected between the first and second pumps 10A and 10B and the one-way valves 19A and 19B via suction valves 18A and 18B which are normally closed solenoid valves. The first and second hydraulic pressure paths 20A and 20B are connected to the discharge sides of the first and second pumps 10A and 10B via the first and second dampers 13A and 13B.

  During normal braking in which each wheel is not likely to lock, each inlet valve 6A to 6D is demagnetized and opened, and each outlet valve 9A to 9D is demagnetized and closed. The brake hydraulic pressure output from the 1 output port 1A acts on the left front wheel and right rear wheel brakes 2A and 2B via the inlet valves 6A and 6B. The brake hydraulic pressure output from the second output port 1B of the master cylinder M acts on the right front wheel brakes 2C and 2D via the inlet valves 6C and 6D.

  When the wheel is about to enter the locked state during the braking, the inlet valve corresponding to the wheel that is about to enter the locked state among the inlet valves 6A to 6D is excited and closed, and the outlet valves 9A to 9D. Of these, the outlet valve corresponding to the wheel is excited and opened. Thereby, a part of the brake fluid pressure of the wheel that is about to enter the locked state is absorbed by the first reservoir 8A or the second reservoir 8B, and the brake fluid pressure of the wheel that is about to enter the locked state is reduced. It will be.

  Further, when the brake fluid pressure is kept constant, the inlet valves 6A to 6D are excited and closed, and the outlet valves 9A to 9D are demagnetized and closed, and when the brake fluid pressure is further increased. For example, the inlet valves 6A to 6D may be demagnetized and opened, and the outlet valves 9A to 9D may be demagnetized and closed.

  By controlling the demagnetization / excitation of the inlet valves 6A to 6D and the outlet valves 9A to 9D in this way, braking can be efficiently performed without locking the wheels.

  By the way, during the antilock brake control as described above, the electric motor 11 is rotated, and the first and second pumps 10A and 10B are driven in accordance with the operation of the electric motor 11. Therefore, the first and second pumps are driven. The brake fluid absorbed in the reservoirs 8A and 8B is sucked into the first and second pumps 10A and 10B, and then passes through the first and second dampers 13A and 13B to the first and second output hydraulic pressure paths 3A and 3B. Refluxed. Such a recirculation of the brake fluid can prevent an increase in the depression amount of the brake pedal 4 due to the absorption of the brake fluid in the first and second reservoirs 8A and 8B. In addition, the pulsation of the discharge pressure of the first and second pumps 10A and 10B is suppressed by the action of the first and second dampers 13A and 13B, and the operation feeling of the brake pedal 4 is not hindered by the reflux.

  Thus, the first and second pumps 10A and 10B are operated as master cylinders by energizing and opening the suction valves 18A and 18B and operating the electric motor 11 with the cut valves 17A and 17B energized and closed. The brake fluid sucked and pressurized from the M side is discharged to the first and second hydraulic pressure paths 20A and 20B.

  Pressure sensors 15A and 15B for detecting brake fluid pressure are connected to the left front wheel and right front wheel brakes 2A and 2C.

  In FIG. 2, in the left front wheel brake 2 </ b> A that is a disc brake with a parking brake mechanism, a first friction pad 72 and a second friction pad 73 are arranged opposite to each other of a brake disc 71 that rotates with the wheel. These first and second friction pads 72 and 73 are composed of linings 72a and 73a that can be brought into contact with the brake disc 71, and back plates 72b and 73b fixed to the back surfaces of the linings 72a and 73a. The back plates 72 b and 73 b are supported by a bracket 74 fixed to the vehicle body so as to be movable in the axial direction of the brake piston 78. A brake caliper 75 straddling the first and second friction pads 72 and 73 is supported on the bracket 74 so as to be movable in the axial direction of the brake piston 78.

  The brake caliper 75 includes a first sandwiching arm 75a facing the back plate 72b of the first friction pad 72 and a second sandwiching arm 75b facing the back plate 73b of the second friction pad 73. The second sandwiching arms 75 a and 75 b are integrally connected by a bridging portion 75 c that passes through the outer periphery of the brake disc 71. The first pinching arm 75 a is provided with a cylinder hole 76, and a cup-shaped brake piston 78 is slidably fitted into the cylinder hole 76 via a seal member 77. The front end of the brake piston 78 facing the back plate 72b of the first friction pad 72 is connected to the open end of the cylinder hole 76 by a bellows-like dust cover 79, and the brake facing the back of the brake piston 78 A hydraulic chamber 80 is formed in the first clamping arm 75a, and the brake hydraulic chamber 80 is connected to the inlet valve 6A via a port 81 provided in the first clamping arm 75a.

  An adjusting mechanism 82 is provided in the first pinching arm 75a of the brake caliper 75, and this adjusting mechanism 82 is connected to the brake piston 78 so as not to be relatively rotatable and is accommodated in the brake hydraulic pressure chamber 80. An adjusting nut 83, an adjusting bolt 84 whose front end is screwed to the adjusting nut 83, and a rear portion of the brake fluid pressure chamber 80, and capable of moving in the axial direction while preventing rotation around the axis. And a relay piston 85 that is liquid-tightly and slidably fitted to the brake caliper 75, and is integrally and coaxially connected to the rear portion of the adjustment bolt 84 so as to be liquid-tight and slidable to the relay piston 85. And a small piston 86 that is elastically biased in the direction of frictional engagement with the relay piston 85.

  A relay cylinder hole 87 having a diameter smaller than that of the cylinder hole 76 is coaxially provided at an end of the first clip arm 75a of the brake caliper 75 opposite to the brake disc 71, and a rear portion of the stepped relay piston 85 is provided. The front part is inserted into the rear part of the cylinder hole 76 and is slidably fitted into the relay cylinder hole 87 via the seal member 88. Moreover, the brake caliper 75 and the relay piston 85 are fitted with both ends of a regulation pin 89 that has an axis parallel to the cylinder hole 76 and the relay cylinder hole 87 and is disposed at a position offset from the axis of the cylinder hole 76. The As a result, the relay piston 85 is prevented from rotating around an axis that is coaxial with the cylinder hole 76 and the relay cylinder hole 87 and can be moved along the axis to be supported by the brake caliper 75. .

  The relay piston 85 is coaxially provided with a small cylinder hole 91 having a tapered clutch surface 90 at the front end opening. On the other hand, at the rear part of the adjusting bolt 84, a movable clutch body 92 that can be frictionally engaged with the clutch surface 90 and a small piston 86 that fits in the small cylinder hole 91 in a liquid-tight and slidable manner are coaxial. And it is connected continuously.

  A retainer 95 engaged and supported by a clip 94 mounted on the inner surface of the cylinder hole 76 has one end of a clutch spring 93 that exerts a spring force that frictionally engages the movable clutch body 92 with the clutch surface 90 of the relay piston 85. The other end of the clutch spring 93 comes into contact with the movable clutch body 92 via a ball bearing 96.

  The adjustment nut 83 and the adjustment bolt 84 are engaged with each other by a quick screw 97 having a plurality of threads and a groove having a coarse pitch. One end of an over-adjustment prevention spring 98 that exerts a spring force that urges the adjustment nut 83 toward the brake piston 78 is brought into contact with the adjustment nut 83 and is engaged and supported by a clip 99 mounted on the inner surface of the brake piston 78. The other end of the over-adjustment prevention spring 98 is brought into contact with and supported by the retainer 100.

  The adjustment nut 83 and the brake piston 78 cannot be rotated relative to each other due to the concave-convex engagement of the contact portions, and the back plate 72b of the first friction pad 72 and the brake piston 78 cannot be rotated relative to each other due to the concave-convex engagement. It is.

  In such an adjustment mechanism 82, when hydraulic pressure is supplied to the brake hydraulic pressure chamber 80 during normal braking, the brake piston 78 that receives the hydraulic pressure elastically deforms the seal member 77 in the cylinder hole 76 in FIG. When the first friction pad 72 is pressed against one side of the brake disk 71, the brake caliper 75 moves to the right in the direction opposite to the moving direction of the brake piston 78, and the second pinching arm 75b moves. The second friction pad 73 is pressed against the other side of the brake disc 71. As a result, the first and second friction pads 72 and 73 come into contact with both surfaces of the brake disc 71 with an equal surface pressure, and a braking force for braking the wheel is generated.

  During the braking, the hydraulic pressure supplied to the brake hydraulic pressure chamber 80 does not cause the adjustment nut 83 to generate an axial load, but the movable clutch body 92 integrated with the adjustment bolt 84 meshing with the adjustment nut 83. In this case, a rightward load having a magnitude obtained by multiplying the cross-sectional area of the small piston 86 by the hydraulic pressure is generated, and a frictional engagement force corresponding to the load acts between the movable clutch body 92 and the clutch surface 90 of the relay piston 85. To do.

  Incidentally, since the hydraulic pressure acting on the brake hydraulic pressure chamber 80 during normal braking is relatively low, the frictional engagement force acting between the movable clutch body 92 and the relay piston 85 is also relatively small. Therefore, when the brake piston 78 moves forward with the progress of wear of the linings 72 a and 73 a of the first and second friction pads 72 and 73, the adjustment nut 83 moves forward together with the brake piston 78 by the elastic force of the over-adjustment prevention spring 98. Then, the movable clutch body 92 integrated with the adjustment bolt 84 meshing with the adjustment nut 83 is separated from the clutch surface 90 of the relay piston 85 against the hydraulic pressure acting on the brake hydraulic pressure chamber 80 and the elastic force of the clutch spring 93. It is.

  When the movable clutch body 92 is separated from the clutch surface 90 of the relay piston 85, the adjustment bolt 84 urged to the right by the hydraulic pressure acting on the movable clutch body 92 and the elastic force of the clutch spring 93 becomes an unrotatable adjustment nut. While moving in the fast screw 97 relative to 83, the movable clutch body 92 moves to the right while being relatively rotated and the clutch surface 90 of the relay piston 85 is engaged again. At this time, the movable clutch body 92 can be smoothly rotated by the action of the ball bearing 96 arranged between the clutch spring 93.

  In this way, as the wear of the linings 72a and 73a in the first and second friction pads 72 and 73 progresses, the adjustment nut 83 moves relative to the left side with respect to the adjustment bolt 84 so as to compensate for the amount of wear. Therefore, the clearance between the linings 72a and 73a of the first and second friction pads 72 and 73 and the brake disk 71 during non-braking can be automatically maintained constant.

  When the hydraulic pressure acting on the brake hydraulic pressure chamber 80 is reduced to release the brake state, the brake piston 78 moves backward due to the deformation restoring force of the seal member 77, but the reverse force is transmitted via the adjustment nut 83 and the adjustment bolt 84. Since the movable clutch body 92 is engaged with the clutch surface 90 of the relay piston 85, the relative rotation of the adjustment bolt 84 with respect to the adjustment nut 83 is restricted. Therefore, the brake piston 78 can only move backward by a stroke corresponding to the backlash between the adjusting nut 83 and the adjusting bolt 84, and the backlash is between the first and second friction pads 72 and 73 and the brake disk 71. Proper clearance of minutes is given.

  When strong braking is performed, the automatic adjustment is performed until the hydraulic pressure in the brake hydraulic pressure chamber 80 rises to a predetermined value that causes the brake caliper 75 to deform, and the hydraulic pressure reaches the predetermined value. When exceeding, the movable clutch body 92 is strongly pressed against the clutch surface 90 of the relay piston 85 by hydraulic pressure, so that the movable clutch body 92 and the relay piston 85 are coupled so as not to be relatively rotatable. As a result, the adjustment bolt 84 is restrained to be non-rotatable and the adjustment nut 83 that is originally non-rotatable remains on the adjustment bolt 84. Therefore, when the brake piston 78 further moves forward due to elastic deformation of the brake caliper 75 due to hydraulic pressure, While compressing the adjustment prevention spring 98, only the brake piston 78 moves forward leaving the adjustment nut 83. In this way, over-adjustment between the adjusting nut 83 and the adjusting bolt 84 when strong braking is performed is prevented.

  Referring also to FIG. 3, the first sandwiching arm 75 a of the brake caliper 75 has a bottomed cylindrical casing main body 24 having an end wall 24 a at the rear end opposite to the left front wheel brake 2 </ b> A. And a plurality of, for example, four bolts 25, and nuts 26 screwed into the bolts 25, respectively, and a casing 23 comprising a cylindrical sleeve 36 fitted and fixed in the casing main body 24. It is concluded by. That is, the flange 27 provided integrally with the first sandwiching arm 75a and the flange 28 provided integrally with the front end portion of the casing main body 24 are fastened by the bolts 25 ... and nuts 26 ....

  In addition, three bolts 25 except for one of the four bolts 25 are arranged on a virtual circle C centered on the axis of the cylinder hole 76 in a plane perpendicular to the axis of the cylinder hole 76. On the other hand, the remaining one bolt 25 is arranged at a position shifted from the virtual circle C, and the arrangement of the bolts 25. The casing 23 is fastened to the first pinching arm 75a of the brake caliper 75 with the position kept constant.

  In the casing 23, the parking operation mechanism 30 that can obtain the parking brake state of the left front wheel brake 2A according to the operation of the parking control hydraulic pressure, and the parking operation state of the parking operation mechanism 30 are provided. A lock mechanism 31 disposed behind the parking operation mechanism 30 is provided so as to be mechanically locked and to perform an unlock operation according to the action of the parking release control hydraulic pressure.

  Referring also to FIG. 4, a first sliding hole formed in the casing main body 24 with a larger diameter than the relay cylinder hole 87 so that the rear end of the relay cylinder hole 87 faces the front end coaxially. 32, a screw hole 33 having a smaller diameter than the first sliding hole 32 and coaxially connected to the rear end of the first sliding hole 32, and a diameter smaller than the screw hole 33 and coaxial to the rear end of the screw hole 33. An attachment hole 34 that is continuous and is closed at the rear end by the end wall 24 a of the casing 24 is provided, and an annular step 35 that faces the front side is formed between the first sliding hole 32 and the screw hole 33. .

  A cylindrical sleeve 36 is fitted into the mounting hole 34, and the male screw portion 37 provided on the outer peripheral portion of the front end of the sleeve 36 is in contact with the end wall 24a until the rear end of the sleeve 36 contacts the end wall 24a. The sleeve 36 is screwed into the screw hole 33, whereby the sleeve 36 is fixed in the casing main body 24 so that the front end thereof is disposed behind the stepped portion 35.

  The sleeve 36 has a smaller diameter than the first sliding hole 32, a second sliding hole 38 coaxially connected to the rear end of the first sliding hole 32, and a smaller diameter than the second sliding hole 38. A guide hole 39 coaxially connected to the rear end of the second slide hole 38, a third slide hole 40 having a diameter larger than that of the guide hole 39 and connected coaxially to the rear end of the guide hole 39, and a third slide hole A fourth slide hole 41 having a diameter larger than that of the third slide hole 40 and coaxially connected to the rear end of the third slide hole 40, and a regulation step portion facing forward between the second slide hole 38 and the guide hole 39. 42 is formed, and an annular stepped portion 43 is formed between the third and fourth sliding holes 40 and 41 so as to face rearward.

  The parking operation mechanism 30 includes a parking piston 44 slidably fitted in the first sliding hole 32 and a pressing piston accommodated in the first sliding hole 32 so as to be axially slidable in front of the parking piston 44. 45 and a plurality of disc springs 46 interposed between the parking piston 44 and the pressing piston 45.

  A small-diameter portion 44 a that is slidably fitted in the second sliding hole 38 is coaxially and integrally provided at the rear end of the parking piston 44, and the rear portion 35 of the casing main body 24 in the casing 23 and the rear of the parking piston 44. Between the ends, an annular parking control fluid pressure chamber 47 is formed for allowing the parking control fluid pressure to act on the parking piston 44 from the back side, and the parking control fluid pressure chamber 47 is sealed from both axial sides. The annular seal members 48 and 49 are mounted on the outer periphery of the parking piston 44 and the outer periphery of the small diameter portion 44a of the parking piston 44. At the front end of the pressing piston 45, a pressing projection 45a inserted into the relay cylinder hole 87 is integrally projected so as to abut on the rear end of the relay piston 85.

  A concave portion 44b is provided at the center of the front end of the parking piston 44, and an insertion cylinder portion 45b inserted into the concave portion 44b is provided coaxially and integrally with the central portion of the rear end of the pressing piston 45. Moreover, the outer diameter of the insertion cylinder 45b is set to be smaller than the inner diameter of the recess 44b so as to allow relative displacement of the pressing piston 45 in the radial direction with respect to the parking piston 44. The inner diameter of the first sliding hole 32 is set so as not to contact the inner surface of the first sliding hole 32 even if the relative displacement in the radial direction of the insertion cylinder 45b in the concave portion 44b occurs. .

  On the other hand, the free length of the disc springs 46 is set to such a value that the spring load cannot be exerted when the parking piston 44 is in the retreat limit so that the volume of the parking control hydraulic pressure chamber 47 is minimized. In this state, at least a part of the insertion tube portion 45b is inserted into the recess 44b.

  In this way, the parking piston 44 and the pressing piston 45 sandwiching the plurality of disc springs 46 are connected in the axial direction while allowing relative displacement in the radial direction, and the parking operation mechanism 30 is placed in the casing 23. Assembling work becomes easy.

  An air chamber 50 is formed in the front portion of the casing main body 24 in the casing 23 so as to face the front end of the parking piston 44, and the pressing piston 45 and the disc springs 46 are accommodated in the air chamber 50. A small air chamber 51 is formed between the relay piston 85 and a small piston 86 that is fluid-tightly and slidably fitted to the relay piston 85, and the shafts of the relay piston 85 and the small piston 86 are provided. In order to avoid the pressurization / decompression of the small air chamber 51 due to the relative movement in the direction, the relay piston 85 is passed through the front end of the small air chamber 51 and the air passage 52 opens at the rear end to the rear end of the relay piston 85. Is provided. On the other hand, a groove 53 for allowing the air passage 52 to communicate with the air chamber 50 is formed on the front end surface of the pressing protrusion 45a provided integrally with the front end of the pressing piston 45 so as to contact the rear end of the relay piston 85. Provided.

  Incidentally, the first arm portion 75a of the brake caliper 75 and the casing main body 24 of the casing 23 are fastened by a plurality of bolts 25 ... and nuts 26 ... but between the coupling surfaces of the first arm portion 75a and the casing main body 24. Is provided with an O-ring 54 made of an elastic material for blocking the air chamber 50 from the outside.

  Moreover, the O-ring 54 is attached to at least one of the first arm portion 75a and the casing main body 24, for example, an annular groove 55 provided in the casing main body 24. The annular groove 55 has a volume of the air chamber 50 that is parked. The O-ring 54 is formed to allow expansion / contraction as the piston 44 changes in accordance with the axial movement of the piston 44, and the O-ring 54 absorbs the volume change of the air chamber 50.

  The locking mechanism 31 slides in the third and fourth sliding holes 40 and 41 of the sleeve 36 on the rear side of the parking piston 44 so that a forward biasing force acts when the parking piston 44 moves forward. A locking piston 56 that can be fitted and allowed to act on the rear side of the parking release control hydraulic pressure, and a small-diameter portion 44a that the parking piston 44 is integrally provided at the rear portion thereof is integrated and coaxially connected. A cylindrical holding cylinder 57 provided, and spherical bodies 58, 58 as a plurality of locking elements which are held at a plurality of locations in the circumferential direction of the holding cylinder 57 so as to be movable in the direction along the radial direction of the holding cylinder 57. In the axial direction of the holding cylinder 57 so as to contact each of the spheres 58, 58 from the inner side of the holding cylinder 57 and sandwich the spheres 58, 58. So as to be inserted movably in the front end of the lock piston 56 includes an insertion shaft 59 being integrally connected to.

  The lock piston 56 is formed between a small diameter portion 56a slidably fitted in the third sliding hole 40 and an annular stepped portion 56c facing the front of the small diameter portion 56a. A large-diameter portion 56b that is coaxially connected to the rear portion and is slidably fitted into the fourth sliding hole 41 is integrally provided.

  Between the step portion 56c of the lock piston 56 and the step portion 43 of the sleeve 36 in the casing 23, an annular parking release control hydraulic pressure chamber 60 is formed between the lock piston 56 and the sleeve 36 so as to face the front side of the lock piston 56. A spring chamber 61 is formed between the end wall 24 a of the casing main body 24 and the lock piston 56 in the casing 23.

  On the outer periphery of the small-diameter portion 56a and the large-diameter portion 56b of the lock piston 56, an annular seal that seals the parking release control hydraulic pressure chamber 60 from both sides in the axial direction and is in sliding contact with the third and fourth sliding holes 39, 40 Members 62 and 63 are mounted.

  An annular chamber 66 is formed between the outer periphery of the sleeve 36 in the casing 23 and between the casing main body 24 at a portion corresponding to the parking release control hydraulic pressure chamber 60. A plurality of communication holes 67... Communicating with the release control hydraulic pressure chamber 60 are provided, and a pair of annular seal members 68 and 69 sandwiching the annular chamber 66 therebetween are formed on the inner surface of the mounting hole 34 in the casing main body 24. It is mounted on the outer periphery of the sleeve 36 so as to make a resilient contact.

  A spring 64 is contracted between the end wall 24 a of the casing main body 24 and the lock piston 56, and the lock piston 56 is elastically biased toward the front side by the spring force of the spring 64. Moreover, the spring load of the spring 64 is set smaller than the spring load of the clutch spring 93 in the adjustment mechanism 82.

  The holding cylinder 57 is formed to have an outer diameter that can be inserted into the guide hole 39 in the sleeve 36, and holding holes 65 are provided at a plurality of positions spaced in the circumferential direction of the holding cylinder 57. The spheres 58 are inserted and held in their holding holes 65.

  Further, the insertion shaft 59 has a small-diameter shaft portion 59a on the front side for disposing the spheres 58 inward in the radial direction when the parking piston 44 is in the retreat limit, and the parking piston 44 advances from the retreat limit. Accordingly, when the lock piston 56 moves forward to the forward movement position, the large-diameter shaft portion 59b that disposes the spherical bodies 58 ... radially outward, and the contact positions of the spherical bodies 58 ... according to the forward movement of the lock piston 56. Are coaxially and continuously provided through a tapered portion 59c that changes the small diameter shaft portion 59a to the large diameter shaft portion 59b.

  By the way, when the parking piston 44 is in the backward limit and the lock piston 56 is also in the backward limit, the holding cylinder 57 integral with the parking piston 44 is inserted into the guide hole 39, and the insertion shaft 59 has a small diameter. The shaft portion 59 a is in a position corresponding to the holding cylinder 57. Therefore, the spheres 58... Held by the holding cylinder 57 are in the radially inner position and are sandwiched between the guide hole 39 and the small diameter shaft portion 59a.

  As shown in FIG. 5, when the parking piston 44 advances from the retreat limit and the lock piston 56 advances by the spring force of the spring 64 accordingly, the large diameter shaft passes from the small diameter shaft portion 59a of the insertion shaft 59 through the taper portion 59c. In this case, the holding cylinder 57 advances to a position where each spherical body 58 is brought into contact with the inner surface of the second sliding hole 38 having a diameter larger than that of the guide hole 39. Thus, each of the spheres 58 pushed up by the large-diameter shaft portion 59b comes into contact with the regulation step portion 42 between the second sliding hole 38 and the guide hole 39, so that the backward movement is regulated. That is, the retraction of the holding cylinder 57 holding the spheres 58, that is, the parking piston 44 is restricted.

  6, the tapered portion 59c that functions to push up the spheres 58 from the radially inward position in contact with the small diameter shaft portion 59a to the radially outward position in contact with the large diameter shaft portion 59b is provided on the insertion shaft 59. The angle α formed with respect to the axis is set to 20 to 60 degrees.

  In addition, the regulation step portion 42 that comes into contact with the spheres 58 from behind in the locked state has a curved surface shape in which the cross-sectional shape in a plane including the axis of the casing 23 is recessed with a radius R equal to or larger than the radius of the spheres 58. Then, in the cross section, the spheres 58 are formed in a curved shape so that the spheres 58 are in contact with almost the entire surface of the formation step 43, and the spheres 58 are controlled in a state where the rearward movement is restricted by the restriction step 42. The contact area of the regulation step 42 is relatively large.

  The parking control fluid pressure acting on the parking control fluid pressure chamber 47 and the parking release control fluid pressure acting on the parking release control fluid pressure chamber 60 function as a fluid pressure generation source when driven by the electric motor 11. The hydraulic pressure discharged from the first pump 10A is controlled by the hydraulic pressure control means 105A. The hydraulic pressure control means 105A communicates with the casing main body 24 through the parking control hydraulic pressure chamber 47. The casing main body 24 is provided so as to be connected to the first normally closed electromagnetic valve 106 interposed between the hydraulic pressure path 108 and the inlet valve 6A provided, and the annular chamber 66 communicating with the parking release control hydraulic pressure chamber 60. A hydraulic pressure passage 109 and a second normally closed electromagnetic valve 107 interposed between the inlet valve 6A and the hydraulic pressure control means 105A. Provided integrally with the casing main body 24 is accommodated in the bulging portion 24b that bulges laterally from the casing main body 24 in.

  Further, in the casing main body 24 of the casing 23, as shown in FIG. 3, there are a bleeder pipe 101 leading to the parking control hydraulic pressure chamber 47 and a bleeder pipe 102 leading to the annular chamber 66 connected to the parking release control hydraulic pressure chamber 60. The bleeder tubes 101 and 102 are integrally provided so as to extend obliquely upward on the side opposite to the bulging portion 24c, and the bleeder tubes 101 and 102 are closed by caps 103 and 104, respectively.

  When obtaining the parking brake state, the first pump 10A is driven by the electric motor 11, the cut valve 17A is excited and closed, the suction valve 18A is excited and opened, and the hydraulic pressure control means 105A is first closed normally. The electromagnetic valve 106 is excited and opened. Thus, the brake fluid pressure is applied to the brake fluid pressure chamber 80, the parking control fluid pressure is applied to the parking control fluid pressure chamber 47, and the second normally closed solenoid valve 107 is excited and opened to perform parking. By applying hydraulic pressure to the release control hydraulic pressure chamber 60, the brake piston 78 and the parking piston 44 are advanced while suppressing the forward movement of the lock piston 56. Next, the first electromagnetic normally closed solenoid valve 106 is demagnetized and closed, the drive of the first pump 10A by the electric motor 11 is stopped, the cut valve 17A is demagnetized and opened, and the suction valve 18A is demagnetized and closed. When the valve is operated, the hydraulic pressure in the parking release control hydraulic pressure chamber 60 is released, the lock piston 56 is moved forward by the spring force of the spring 64, and the lock mechanism 31 is locked according to the advance of the parking piston 44 and the lock piston 56. To do. However, when the forward movement of the lock piston 56 is completed, the first normally closed solenoid valve 106 is temporarily excited and opened to release the residual pressure in the parking control hydraulic chamber 47.

  When the parking piston 44 is thus locked by the forward movement, the pressing piston 45 is pushed in the forward direction via the disc springs 46, and the relay piston 85 is moved by the pressing protrusion 45a provided at the front end of the pressing piston 45. The forward movement of the relay piston 85 causes the brake piston 78 to move forward via the movable clutch body 92, the adjustment bolt 84 and the adjustment nut 83, and the first and second friction pads 72 are the same as during normal braking. , 73 are pressed against both surfaces of the brake disc 71 to generate a braking force, whereby a parking brake state can be obtained.

  In the process of obtaining the parking brake state, the relay piston 85 and the movable clutch body 92 are frictionally engaged with each other by the pressing force of the parking piston 44 so that they cannot be rotated relative to each other, so that the relative rotation of the adjusting bolt 84 and the adjusting nut 83 is restricted. Therefore, when the left front wheel brake 2A functions as a parking brake, the automatic adjustment by the adjustment mechanism 82 is not performed.

  Further, when the parking brake state is obtained during the normal brake operation, when the detected value of the pressure sensor 15A is sufficiently high, the master cylinder M is used as a hydraulic pressure generation source, and the first pump 10A is not driven by the electric motor 11. Moreover, it is only necessary to operate the hydraulic pressure control means 105A with the cut valve 17A demagnetized and opened and the suction valve 18A demagnetized and closed. When the detection value of the pressure sensor 15A is low, the electric motor 11 While the pump 10A is being driven, the cut valve 17A is energized and closed, the suction valve 18A is energized and opened, and the hydraulic pressure control means 105A is operated. Further, the detection value of the pressure sensor 15A is activated. First, the cut valve 17A is excited and closed while the first pump 10A is driven by the electric motor 11. The suction valves 18A energized and opened, it may be allowed to operate the fluid pressure control means 105A with.

  When releasing the parking brake state, the first pump 10A is driven by the electric motor 11, the cut valve 17A is excited and closed, the suction valve 18A is excited and opened, and the first and The second normally closed solenoid valves 106 and 107 are excited and opened. As a result, the hydraulic pressures in the brake hydraulic pressure chamber 80, the parking control hydraulic pressure chamber 47, and the parking release control hydraulic pressure chamber 60 increase simultaneously. In the pressure increasing process, first, the hydraulic pressure larger than the spring force of the spring 64 is obtained. Acts on the lock piston 56 so that the lock piston 56 moves backward, and then acts on the small piston 86 rather than the forward pressing force acting on the parking piston 44 by the hydraulic pressure of the parking control hydraulic pressure chamber 47. The hydraulic pressure in the reverse direction and the resultant force of the clutch spring 93 increase, and the parking piston 44 moves backward. As a result, the lock mechanism 31 is unlocked and the parking brake state is released.

  Incidentally, the volume of the spring chamber 61 formed in the sleeve 36 between the lock piston 56 and the end wall 24a of the casing main body 24 changes according to the axial movement of the lock piston 56, and this spring chamber. In order to avoid the pressure of 61 from being increased / decreased due to the change in its volume, the large-diameter portion 56a of the lock piston 56 and the insertion shaft 59 are provided with a communication passage 110 coaxially connected to the spring chamber 61 so that the parking piston 44 is provided coaxially with a communication path 111 that allows the communication path 110 to communicate with the air chamber 50, and the spring chamber 61 communicates with the air chamber 50, thereby preventing the spring chamber 61 from being pressurized or decompressed.

  A screw hole 112 as an opening is coaxially provided in the end wall 24a of the casing main body 24 in the casing 23 at a portion where the back surface of the lock piston 56 faces, and the screw hole 112 is a bolt 113 as a lid member. It is detachably closed by screwing in.

  On the other hand, the lock piston 56 is provided with a tool connecting portion 115 formed by engraving a female screw 114 on the inner surface of the rear portion of the communication passage 110, and the bolt 113 is loosened and removed as shown in FIG. The tool 116 inserted from the screw hole 112 opened in the step can be detachably connected to the tool connecting portion 115.

  The right front wheel brake 2C is configured in the same manner as the left front wheel brake 2A described above. When the parking brake state of the right front wheel brake 2C is obtained, the suction valve 18B is excited and opened, and a cut valve is provided. By operating the electric motor 11 with 17B excited and closed, the second pump 10B can function as a hydraulic pressure generation source to control the operation of the hydraulic pressure control means 105B.

  Next, the operation of this embodiment will be described. By controlling the hydraulic pressure generated by the master cylinder M or the first and second pumps 10A, 10B by the hydraulic pressure control means 105A, 105B, the parking piston of the parking operation mechanism 30 is provided. When the parking control hydraulic pressure is applied to the parking control hydraulic pressure chamber 47 facing the rear side of the parking brake 44, the parking brake state of the left front wheel and right front wheel brakes 2A and 2C can be obtained by the forward movement of the parking piston 44. In addition, since the parking operation state of the parking operation mechanism 30 is mechanically locked by the lock mechanism 31, the parking brake state can be automatically obtained, and when the parking brake state is released, the parking release control hydraulic pressure is obtained. Can be applied to the lock mechanism 31. It is possible to obtain the parking brake state automatically by a simple structure without power consumption in the parking brake state.

  In addition, the parking operation mechanism 30 has a parking piston 44 that is slidably fitted into the first sliding hole 32 of the casing 23 with the back side facing the parking control hydraulic pressure chamber 47, and for the left front wheel and the right front wheel. A plurality of disc springs 46 are interposed between the press pistons 45 connected to the relay piston 85 in the wheel brakes 2A and 2C, and for the left front wheel and the right front wheel by the action of the disc springs 46 ... Changes in the parking force acting on the wheel brakes 2A and 2C side with the forward and backward movements of the parking piston 44 can be moderated.

  In addition, since the free length of the disc springs 46 is set to a value at which the spring load cannot be exerted at the retreat limit of the parking piston 44, the spring load by the disc springs 46 is set to the left and right front wheels when the parking brake is released. It can prevent acting on the wheel brakes 2A, 2C side.

  Further, the pressing protrusion 45 a provided at the front end of the pressing piston 45 in the parking operation mechanism 30 is inserted into the relay cylinder hole 87 provided in the first sandwiching arm portion 75 a of the brake caliper 75 and can slide in the relay cylinder hole 87. The parking piston 44 and the pressing piston 45 sandwiching the disc springs 46 are connected to each other in the axial direction while allowing relative displacement in the radial direction. Thus, even if the relay cylinder hole 87 and the first sliding hole 32 are misaligned when the brake caliper 75 and the casing 23 are fastened, the misalignment is absorbed and the pressing protrusion 45a is relayed. It can be reliably inserted into the cylinder hole 87 and brought into contact with the relay piston 85.

  By the way, an air chamber 50 that faces the front surface of the parking piston 44 is formed in the casing 23, and the volume change of the air chamber 50 accompanying the axial movement of the parking piston 44 is absorbed by the expansion and contraction of the O-ring 54. Smooth operation of the parking piston 44, that is, smooth parking brake operation and smooth parking brake release operation can be achieved by avoiding the pressure increase / decrease of the chamber 50.

  Moreover, the O-ring 54 is interposed between the brake caliper 75 and the casing 23 that are fastened to each other, and serves to block the air chamber 50 from the outside. The volume change of the air chamber 50 can be absorbed while reducing the number of parts.

  A flange 27 provided integrally with the first sandwiching arm 75a of the brake caliper 75 and a flange 28 provided integrally with the front end portion of the casing main body 24 in the casing 23 are fastened by a plurality of bolts 25 and nuts 26. However, one of the bolts 25 is disposed at a position shifted from a virtual circle C around the axis of the cylinder hole 76 in a plane perpendicular to the axis of the cylinder hole 76 in the brake caliper 75. On the other hand, since the remaining bolts 25 are arranged on the virtual circle C, the casing 23 is fastened to the first clamping arm 75a of the brake caliper 75 with the relative position around the axis of the cylinder hole 76 being constant. become.

  Thus, the casing 23 can be fastened to the brake caliper 75 so that the relative position of the bulging portion 24b provided in the casing main body 24 of the casing 23 and the bleeder pipes 101 and 102 with respect to the brake caliper 75 is not mistaken. it can.

  Further, the insertion shaft 59 constituting a part of the lock mechanism 31 includes a small-diameter shaft portion 59a on the front side in which the spherical bodies 58 are arranged radially inward when the parking piston 44 is in the retreat limit, and the parking piston 44. When the lock piston 56 advances to the advance position in accordance with the advance from the retreat limit, the large-diameter shaft portion 59b that disposes the respective spheres 58... In response to the advance movement of the lock piston 56. In addition, the spherical bodies 58 are coaxially and integrally connected via a tapered portion 59c that changes the contact position of the spheres 58 from the small diameter shaft portion 59a to the large diameter shaft portion 59b.

  According to such a structure of the insertion shaft 59, when the parking piston 44 moves forward, the lock piston 56 moves forward, so that each sphere 58... Smoothly extends from the small diameter shaft portion 59a to the taper portion 59c of the insertion shaft 59. The spheres 58 are pushed up by being guided to the shaft portion 59b side, and the movement of the spheres 58... Is restricted rearward by the restriction step portion 42 on the casing 23 side, while the large diameter shaft portion 59b moves radially inward. It becomes a regulated state and can maintain a locked state. Further, the parking brake state can be released by causing the parking release control hydraulic pressure to act on the lock piston 56 and retracting the lock piston 56.

  Further, the regulation step portion 42 provided on the sleeve 36 in the casing 23 is formed in a curved surface shape in which a cross-sectional shape in a plane including the axis of the casing 23 is recessed with a radius R equal to or larger than the radius of the sphere 58. In a state where the rearward movement is restricted by 42, the contact area of each of the spheres 58 and the regulation stepped portion 42 becomes relatively large, and the stress acting on the spheres 58 and the sleeve 36 can be relaxed.

  Moreover, since the angle α formed by the taper portion 59c with respect to the axis of the insertion shaft 59 is set to 20 to 60 degrees, the lock piston 56, that is, the insertion shaft 59 of the insertion shaft 59 is avoided while avoiding an unnecessarily large stroke of the insertion shaft 59. It is possible to smoothly push up each sphere 58. That is, when the angle α is less than 20 degrees, the spheres 58 can be pushed up smoothly, but the stroke of the insertion shaft 59 becomes too large, and when the angle α exceeds 60 degrees, As the lock piston 56 advances, the component force for pushing up the spheres 58 is insufficient, and it is difficult to push up the spheres 58 smoothly.

  A screw hole 112 that is closed by a bolt 113 is provided in an end wall 24a of the casing main body 24 in the casing 23 at a portion of the lock mechanism 31 that faces the back surface of the lock piston 56, and a screw hole 112 is provided at a rear portion of the lock piston 56. Since the tool connecting portion 115 capable of detachably connecting the tool 116 inserted from 112 is provided, the lock piston 56 is pulled by pulling the tool 116 connected to the tool connecting portion 115 against the spring force of the spring 64. By forcibly moving backward, the parking brake state can be forcibly released by manual operation, which is convenient for maintenance and inspection.

  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 hydraulic circuit diagram of the brake device for vehicles. It is a longitudinal cross-sectional view of the left front wheel brake at the time of non-parking brake. FIG. 3 is a view taken in the direction of arrow 3 in FIG. 2. FIG. 3 is an enlarged view of a main part of FIG. 2. FIG. 3 is a longitudinal sectional view corresponding to FIG. 2 in a parking brake state. FIG. 6 is a partially enlarged view of FIG. 5. It is sectional drawing which shows the state which connected the tool to the lock piston.

Explanation of symbols

10A, 10B: Pump 23 as a hydraulic pressure source ... Casing 31 ... Lock mechanism 42 ... Restriction step 44 ... Parking piston 56 ... Lock piston 57 ... Holding cylinder 58 ... Sphere 59 as a locking element ... Insertion shaft 59a ... Small diameter shaft portion 59b ... Large diameter shaft portion 59c ... Taper portions 105A, 105B ... Hydraulic pressure control means M ... Liquid Master cylinder as a pressure source

Claims (1)

  A parking piston (44) that is slidably fitted to the casing (23) 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 ( 44) is automatically locked according to the forward movement of the parking piston (44) 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 (31) provided in the casing (23) on the rear side of the parking piston (44), a hydraulic pressure source (10A, 10B, M), and the hydraulic pressure source (10A, 10B, M) The hydraulic pressure control means (1) capable of obtaining the parking control hydraulic pressure and the parking release control hydraulic pressure by controlling the hydraulic pressure generated by 5A, 105B), and the locking mechanism (31) is provided on the rear side of the parking piston (44) so that a forward biasing force acts at least when the parking piston (44) moves forward. And a lock piston (56) which is slidably fitted to the casing (23) and allows the control pressure for parking release to be applied to the rear, and a rear part of the parking piston (44). A cylindrical holding cylinder (57) arranged coaxially and a lock that is held at a plurality of locations in the circumferential direction of the holding cylinder (57) so that the holding cylinder (57) can move in the radial direction. An element (58) and each locking element (58) are contacted from the inner side of the holding cylinder (57) so that each locking element (58) is placed between the inner surface of the casing (23). The insertion shaft (59) is integrally provided at the front end of the lock piston (56) so as to be inserted in the holding cylinder (57) so as to be relatively movable in the axial direction. In the state where the parking piston (44) is in the retreat limit, the front-side small-diameter shaft portion (59a) for disposing each locking element (58) on the radially inner side, and the parking piston (44) A large-diameter shaft portion (59b) for disposing each lock element (58) on the radially outward side when the lock piston (56) advances to the advance position in accordance with the advance from the retreat limit, Coaxially via a taper portion (59c) that changes the contact position of each lock element (58) from the small diameter shaft portion (59a) to the large diameter shaft portion (59b) in accordance with the forward movement of the lock piston (56). Or The angle formed by the tapered portion (59c) with respect to the axis of the insertion shaft (59) is set to 20 to 60 degrees, and the inner surface of the casing (23) has the lock There is provided a regulation step (42) that can contact from the rear side each locking element (58) that is pushed forward in the radial direction by the large-diameter shaft portion (59b) when the piston (56) is in the forward movement position. A parking brake device.

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