JP2008049736A - Vehicle brake device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle brake device preventing drag of a brake block caused by thermal expansion of a hydraulic fluid. <P>SOLUTION: A free piston 12 stops the flow of the hydraulic fluid at a cylinder 21 at the time of brake release, thereby adjusting the brake clearance between a disk rotor 1 and the brake block 9 in this vehicle brake device. As the hydraulic fluid pressure of a downstream chamber 16 increases over a prescribed value at the time of the brake release, the free piston 12 is moved to the upstream direction against a relief spring 32, and the hydraulic fluid of the downstream chamber 16 flows to an upstream chamber 15 through the clearance between the periphery of the free piston 12 and an upstream side recess 24. This constitution prevents the brake block 9 from hitting against the disk rotor 1 by the thermal expansion of the hydraulic fluid at the time of the brake release. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an improvement in a vehicular brake device that automatically adjusts a brake clearance between a disc rotor and a control wheel.

  Some vehicle brake devices automatically adjust the brake clearance between the disc rotor and the control wheel when the brake is released even if the brake lining is worn (see Patent Documents 1 and 2).

  Hereinafter, the gap between the lining of the brake element and the disc rotor is referred to as a brake gap.

  Conventionally, this type of caliper brake device for a railway vehicle is shown in FIG.

  To explain this, 1 is a disk rotor that rotates integrally with the wheel, 2 is a brake caliper straddling the disk rotor 1, and the linings 3 of the restrictor 9 are arranged on both sides of the disk rotor 1.

  The brake 9 is supported by the brake caliper 2 through a plurality of anchor pins 4 so as to be movable in the axle direction. A return spring 6 is interposed inside each anchor pin 4, and this return spring 6 urges the restrictor 9 in a direction away from the disk rotor 1.

  The brake caliper 2 is provided with a plurality of hydraulic pistons 7. The hydraulic pistons 7 are pushed out of the brake caliper 2 by the hydraulic pressure guided from the brake hydraulic passage 10 to press the brake 9 against the disc rotor 1 to rotate the wheels. Braking.

  An adjuster valve 11 is interposed in the brake hydraulic passage 10, and a free piston 12 is slidably inserted in a housing 20 of the adjuster valve 11. The free piston 12 restricts the return amount of the hydraulic oil in the brake hydraulic passage 10, so that the brake clearance between the disc rotor 1 and the restrictor 9 is automatically adjusted.

  The operation of the adjuster valve 11 will be described based on (a), (b), (c), and (d) of FIG. In the figure, hatched portions indicate the hydraulic oil interposed in the adjuster valve 11.

  In the initial state and when the brake is released, as shown in FIG. 5A, the free piston 12 of the adjuster valve 11 is moved in the direction of arrow B, and the hydraulic piston 7 is brake brake caliper 2 by the urging force of the return spring 6. The disc rotor 1 is held so that the brake clearance with the control wheel 9 becomes a predetermined value.

  During normal operation of the brake, as shown in FIG. 5B, the hydraulic pressure introduced from the brake hydraulic pressure passage 10 increases, so that the free piston 12 of the adjuster valve 11 moves in the direction of arrow A, and the housing 20 of the adjuster valve 11 The hydraulic piston 7 is pushed out from the brake caliper 2 by the hydraulic oil pushed out from the inside, and presses the brake member 9 against the disc rotor 1.

  As the wear amount of the lining 3 increases, the operating stroke of the free piston 12 gradually increases. When the wear amount of the lining 3 eventually exceeds a predetermined value, as shown in FIG. The free piston 12 moves and comes into a bottomed state in contact with the downstream cap 13 and passes through the annular gap 22 defined between the seal ring 19 of the free piston 12 and the housing 20 to reduce the oil for the lining wear. An additional amount is supplied, and the hydraulic piston 7 is pushed out of the brake caliper 2 by this hydraulic oil, and the brake 9 is pressed against the disc rotor 1.

Thereafter, when the brake is adjusted to be released, as shown in FIGS. 5D and 6A, the free piston 12 of the adjuster valve 11 moves and comes into contact with the upstream cap 14 so that the hydraulic oil By stopping the flow, the hydraulic oil corresponding to the required amount of oil is returned from the hydraulic piston 7 into the housing 20, and the hydraulic oil corresponding to the amount of wear of the lining 3 is left in the hydraulic piston 7. The brake clearance with the wheel 9 is automatically adjusted.
Japanese Patent Laid-Open No. 10-110759 JP 2000-179594 A

  However, such a conventional vehicle brake device has a problem that the brake clearance is reduced due to thermal expansion of hydraulic oil.

  More specifically, when the hydraulic oil in the brake hydraulic passage 10 expands due to heat generated during braking or the like when the brake is released as shown in FIG. 6 (a), between the adjuster valve 11 and the hydraulic piston 7. Since the operating hydraulic pressure rises, as shown in FIG. 6B, the brake clearance between the disc rotor 1 and the restrictor 9 decreases from a predetermined value, and the restrictor drags when the restrictor hits the disc rotor 1.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a vehicle brake device that prevents dragging of a brake wheel caused by thermal expansion of hydraulic oil.

  The present invention relates to a return spring that urges the restrictor in a direction away from the disc rotor, a hydraulic piston that presses the restrictor against the disc rotor, a brake hydraulic passage that guides the hydraulic pressure to the hydraulic piston, and a hydraulic piston when the brake is released And an adjuster valve that limits the amount of hydraulic fluid returned from the cylinder, the adjuster valve defining a brake hydraulic pressure passage, a free piston that is slidably interposed in the cylinder and partitions the upstream chamber and the downstream chamber. In a vehicle brake device that adjusts the brake clearance between the disc rotor and the control wheel by stopping the flow of hydraulic oil in the cylinder when the brake is released, the free piston moves in the upstream direction of the cylinder when the brake is released As a result, the upstream chamber and the downstream chamber communicate with each other against the outer periphery of the free piston. It has a flow-side recess and a relief spring that urges the free piston in the downstream direction of the cylinder. The free piston resists the relief spring as the hydraulic pressure in the downstream chamber rises above a predetermined value when the brake is released. The hydraulic oil in the downstream chamber flows to the upstream chamber through the clearance between the outer peripheral portion of the free piston and the upstream concave portion.

  According to the present invention, when the hydraulic pressure in the downstream chamber rises above a predetermined value when the brake is released, the free piston moves against the relief spring in the upstream direction of the cylinder, and the hydraulic oil in the downstream chamber moves to the outer periphery of the free piston. The hydraulic piston pushed out from the brake caliper is pulled back by the flow of the hydraulic oil, and the brake gap is kept at a predetermined value. Accordingly, it is possible to prevent the brake member from being dragged against the disc rotor by the thermal expansion of the hydraulic oil when the brake is released.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view of an adjuster valve 11 provided in a caliper brake device for a railway vehicle. In FIG. 1, the same components as those in the conventional example of FIG. 2A and 2B are cross-sectional views showing the operating state of the adjuster valve 11.

  In this caliper brake device, a brake pressure-increasing mechanism (not shown) generates a hydraulic pressure corresponding to the brake operation amount, and this hydraulic pressure is guided to the hydraulic piston 7 of the brake caliper 2 via the brake hydraulic pressure passage 10, whereby the hydraulic piston 7 However, the lining 3 of the control 9 is pressed against the disk rotor 1 of the wheel to brake the rotation of the wheel.

  The brake 9 is supported by the brake caliper 2 through a plurality of anchor pins 4 so as to be movable in the axle direction. A return spring 6 is interposed inside each anchor pin 4, and this return spring 6 urges the restrictor 9 in a direction away from the disk rotor 1.

  An adjuster valve 11 is interposed in the brake hydraulic passage 10. A cylinder 21 is formed in the housing 20 of the adjuster valve 11, and a free piston 12 is slidably accommodated in the cylinder 21. The cylinder 21 is partitioned into an upstream chamber 15 and a downstream chamber 16 by the free piston 12. The upstream chamber 15 communicates with the brake pressure increasing mechanism of the vehicle via a pipe (not shown), and the downstream chamber 16 communicates with the hydraulic piston 7 of the brake caliper 2. An upstream cap 14 and a downstream cap 13 are fastened to both ends of the housing 20.

  A seal ring 19 is interposed on the outer peripheral portion of the free piston 12, and the seal ring 19 is in sliding contact with the cylinder 21 to seal between the upstream chamber 15 and the downstream chamber 16. A plurality of grooves 17 and 18 are formed on the outer peripheral surface of the free piston 12 with the seal ring 19 interposed therebetween. Grooves 27 and 28 are formed on both end faces of the free piston 12, respectively.

  An upstream recess 24 and a downstream recess 23 are formed in both ends of the cylinder 21. The seal ring 19 of the free piston 12 comes to a position facing the upstream recess 24 and the downstream recess 23. The hydraulic oil flows around the free piston 12 through annular gaps defined between the free piston 12 and the upstream recess 24 and the downstream recess 23, respectively.

  The adjuster valve 11 moves until the free piston 12 comes into contact with the downstream side cap 13 during braking when the lining 3 is worn, and the seal ring 19 faces the downstream side recess 23 to define an annular gap. The hydraulic oil in the upstream chamber 15 flows to the downstream chamber 16 through this annular gap.

  The adjuster valve 11 includes an upstream retainer 31 that contacts the free piston 12 when the brake is released, and a relief spring 32 that urges the upstream retainer 31 in the downstream direction of the cylinder 21 (rightward in FIG. 1). When the operating hydraulic pressure in the downstream chamber 16 rises above a predetermined value, the free piston 12 moves against the relief spring 32, the seal ring 19 faces the upstream recess 24 to define an annular gap, and the downstream chamber Sixteen hydraulic fluids flow to the upstream chamber 15 through the annular gap.

  As the restricting portion 26 that restricts the stroke in which the upstream retainer 31 moves in the downstream direction of the cylinder 21, an annular step portion on which the outer peripheral end portion of the upstream retainer 31 is seated is formed in the housing 20.

  The coiled relief spring 32 is compressed and interposed between the upstream retainer 31 and the upstream cap 14.

  As shown in FIG. 1, in a state where the free piston 12 contacts the upstream retainer 31 and the upstream retainer 31 contacts the restricting portion 26, the upstream recessed portion 24 is positioned closer to the upstream retainer 31 than the seal ring 19. The seal ring 19 faces the cylinder 21.

  The operation of the adjuster valve 11 will be described with reference to FIGS. In the figure, hatched portions indicate the hydraulic oil interposed in the adjuster valve 11.

  In the initial state and when the brake is released, as shown in FIG. 2A, the hydraulic piston 7 is pulled into the brake caliper 2 by the urging force of the return spring 6, but the free piston 12 contacts the upstream retainer 31. By stopping the flow of the hydraulic oil, the disc rotor 1 is held so that the brake gap between the disc rotor 1 and the restrictor 9 becomes a predetermined value (see FIG. 5A).

  During normal operation of the brake, the hydraulic pressure guided from the brake hydraulic pressure passage 10 to the upstream chamber 15 increases, so that the free piston 12 moves in the downstream direction of the cylinder 21, and accordingly flows out of the housing 20 of the adjuster valve 11. The hydraulic piston 7 is pushed out from the brake caliper 2 by the hydraulic oil and presses the restrictor 9 against the disc rotor 1 (see FIG. 5B).

  When the brake is operated when the lining 3 is worn, the free piston 12 moves more than the above state and comes into a bottomed state in contact with the downstream cap 13, so that the hydraulic oil in the upstream chamber 15 flows downstream from the seal ring 19. It flows to the downstream chamber 16 through an annular gap defined between the side recesses 23, and the hydraulic piston 7 is pushed out from the brake caliper 2 by this hydraulic oil, and presses the brake 9 against the disc rotor 1 [FIG. (See (c))].

  Thereafter, when the brake is adjusted to be released, after the free piston 12 moves to the upstream side, as shown in FIG. 2 (a), the flow of hydraulic oil is stopped by contacting the upstream retainer 31 and stopping the hydraulic oil flow. The required amount of hydraulic fluid is returned from the piston 7 into the housing 20, and the hydraulic fluid corresponding to the amount of wear of the lining 3 is left in the hydraulic piston 7, and the brake clearance between the disc rotor 1 and the control wheel 9 is a predetermined value. [See (d) of FIG. 5].

  From the state shown in FIG. 2A, when the hydraulic oil in the brake hydraulic passage 10 expands due to heat generated during braking, the hydraulic pressure between the adjuster valve 11 and the hydraulic piston 7 exceeds a predetermined value. When it rises, as shown in FIG. 2 (b), it moves in the upstream direction of the cylinder 21 against the relief spring 32, the seal ring 19 faces the upstream recess 24, and the hydraulic oil in the downstream chamber 16 is moved to the arrow. As shown in FIG. 5, the gas flows to the upstream chamber 15 through an annular gap 29 defined between the seal ring 19 and the upstream recess 24. When the hydraulic piston 7 is drawn into the brake caliper 2 by this hydraulic oil and the hydraulic pressure between the adjuster valve 11 and the hydraulic piston 7 falls below a predetermined value, the free piston 12 faces the cylinder 21 by the urging force of the relief spring 32. When the free piston 12 stops the flow of hydraulic oil by moving to the closed position, the brake clearance between the disc rotor 1 and the control wheel 9 is maintained at a predetermined value. In this way, it is possible to prevent the control wheel 9 from hitting the disk rotor 1 due to thermal expansion of the hydraulic oil.

  In the present embodiment, a return spring 6 that urges the restrictor 9 away from the disk rotor 1, a hydraulic piston 7 that presses the restrictor 9 against the disk rotor 1, and a brake hydraulic pressure that guides the hydraulic pressure to the hydraulic piston 7. A passage 10 and an adjuster valve 11 that restricts the amount of hydraulic oil returned from the hydraulic piston 7 when the brake is released are provided. The adjuster valve 11 is slidable on the cylinder 21 that defines the brake hydraulic passage 10. And a free piston 12 that divides the upstream chamber 15 and the downstream chamber 16 from each other. When the brake is released, the free piston 12 stops the flow of the hydraulic oil in the cylinder 21 so that the disc rotor 1 and the brake 9 are braked. In the vehicle brake device that adjusts the clearance, the free piston 12 is located upstream of the cylinder 21 when the brake is released. An upstream recess 24 that communicates the upstream chamber 15 and the downstream chamber 16 against the outer peripheral portion of the free piston 12, and a relief spring 32 that biases the free piston 12 in the downstream direction of the cylinder 21. The free piston 12 moves in the upstream direction of the cylinder 21 against the relief spring 32 as the hydraulic pressure in the downstream chamber 16 rises above a predetermined value when the brake is released, and the hydraulic oil in the downstream chamber 16 Is configured to flow to the upstream chamber 15 through the gap between the outer peripheral portion of the free piston 12 and the upstream concave portion 24, the hydraulic piston 7 pushed out from the brake caliper 2 is pulled back by the flow of the hydraulic oil, and the brake gap is reduced. It is kept at a predetermined value. Thereby, it is possible to prevent the restrictor 9 from hitting the disc rotor 1 due to the thermal expansion of the hydraulic oil when the brake is released.

  In the present embodiment, the adjuster valve 11 includes an upstream retainer 31 that abuts the free piston 12 when the brake is released, and a restricting portion 26 that restricts a stroke in which the upstream retainer 31 moves in the downstream direction of the cylinder 21. Since the relief spring 32 urges the upstream retainer 31 in the direction in which the upstream retainer 31 is pressed against the restricting portion 26, the spring characteristics of the relief spring 32 can be arbitrarily set by interposing the relief spring 32 in advance. it can.

  Next, another embodiment shown in FIG. 3 will be described. This basically has the same configuration as that of the embodiment of FIG. 1, and only different parts will be described. In addition, the same code | symbol is attached | subjected to the same structure part as the said embodiment.

  The adjuster valve 11 includes a downstream retainer 41 that abuts the free piston 12 that has reached the downstream end of the cylinder 21 when the brake is operated, and the downstream retainer 41 in the upstream direction of the cylinder 21 (leftward in FIG. 3). And a return spring 42 for biasing.

  A retaining ring 43 is interposed in the housing 20, and further downstream movement of the retainer 41 is restricted by contacting the retaining ring 43.

  The coiled return spring 42 is compressed and interposed between the downstream retainer 41 and the downstream cap 13.

  A retaining ring 33 is interposed in the housing 20 as a restricting portion 26 that restricts the stroke in which the upstream retainer 31 moves in the downstream direction of the cylinder 21, and the upstream retainer 31 abuts on the retaining ring 33 to further increase the stroke. Movement in the downstream direction of the cylinder 21 (right direction in FIG. 3) is restricted.

  Hereinafter, the operation of the adjuster valve 11 will be described.

  In the initial state and when the brake is released, the hydraulic piston 7 is drawn into the brake caliper 2 by the urging force of the return spring 6 as in the above embodiment, but the free piston 12 abuts on the upstream retainer 31 and the flow of hydraulic oil. Is stopped so that the brake clearance between the disc rotor 1 and the control wheel 9 becomes a predetermined value (see FIG. 5A).

  During normal operation of the brake, the hydraulic pressure guided from the brake hydraulic pressure passage 10 increases, so that the free piston 12 moves in the downstream direction of the cylinder 21, and the hydraulic oil flows out of the housing 20 of the adjuster valve 11 along with this. The piston 7 is pushed out from the brake caliper 2 and presses the restrictor 9 against the disc rotor 1 (see FIG. 5B).

  As the amount of wear of the lining 3 increases, the operating stroke of the free piston 12 gradually increases. When the amount of wear of the lining 3 exceeds a predetermined value, the free piston 12 moves and contacts the downstream retainer 41. When the seal ring 19 comes off the cylinder 21 against the return spring 42 and faces the downstream recess 23 against the return spring 42, the hydraulic oil in the upstream chamber 15 is defined between the seal ring 19 and the downstream recess 23. The hydraulic piston 7 is pushed out of the brake caliper 2 by this hydraulic oil through the annular gap formed, and presses the brake 9 against the disc rotor 1 (see FIG. 5C).

  When the brake is subsequently adjusted, the free piston 12 moves upstream, and then comes into contact with the upstream retainer 31 to stop the flow of hydraulic oil. Returned into the housing 20, the hydraulic oil corresponding to the amount of wear of the lining 3 is left in the hydraulic piston 7, and the brake clearance between the disc rotor 1 and the brake 9 becomes a predetermined value (see FIG. 5D). .

  At the time of the adjustment, the free piston 12 is pushed upstream by the urging force of the return spring 42, so that the seal ring 19 is reliably returned from the downstream recess 23 to the position in sliding contact with the cylinder 21.

  When hydraulic oil in the brake hydraulic passage 10 expands due to heat generated during braking or the like, if the hydraulic pressure between the adjuster valve 11 and the hydraulic piston 7 rises above a predetermined value, the cylinder against the relief spring 32 21 is moved in the upstream direction so that the seal ring 19 faces the upstream recess 24, and the hydraulic oil in the downstream chamber 16 is defined between the seal ring 19 and the upstream recess 24 as indicated by the arrow. It flows to the upstream chamber 15 through. When the hydraulic piston 7 is drawn into the brake caliper 2 by this hydraulic oil and the hydraulic pressure between the adjuster valve 11 and the hydraulic piston 7 falls below a predetermined value, the free piston 12 faces the cylinder 21 by the urging force of the relief spring 32. When the free piston 12 stops the flow of hydraulic oil by moving to the closed position, the brake clearance between the disc rotor 1 and the control wheel 9 is maintained at a predetermined value. In this way, it is possible to prevent the restrictor 9 from hitting the disk rotor 1 due to thermal expansion of the hydraulic oil (see FIG. 2B).

  In the present embodiment, when the free piston 12 moves in the downstream direction of the cylinder 21 exceeding a predetermined stroke when the brake is operated, the downstream side that communicates the upstream chamber 15 and the downstream chamber 16 facing the outer peripheral portion of the free piston 12. A recess 23, a downstream retainer 41 that abuts the free piston 12 that has reached the downstream end of the cylinder 21 when the brake is operated, and a return spring 42 that urges the downstream retainer 41 in the upstream direction of the cylinder 21. The free piston 12 abuts on the downstream retainer 41 and moves in the downstream direction of the cylinder 21 against the return spring 42 when the brake is operated, so that the hydraulic oil in the upstream chamber 15 flows from the outer periphery of the free piston 12 and the downstream recess 23. The flow of the return spring 42 to the downstream chamber 16 through the clearance of the return spring 42 when releasing the brake When the free piston 12 is pushed upstream by the force, the seal ring 19 is reliably returned to the position where it slides into contact with the cylinder 21 from the downstream recess 23, and is guided to the hydraulic piston 7 via the adjuster valve 11. The amount of hydraulic oil to be used can be adjusted accurately.

  Next, another embodiment shown in FIG. 4 will be described. This has basically the same configuration as that of the embodiment of FIG. 3, and only the differences will be described. In addition, the same code | symbol is attached | subjected to the same structure part as the said embodiment.

  The adjuster valve 11 has a coiled return spring 45 compressed and interposed between the free piston 12 and the downstream cap 13. The return spring 45 urges the free piston 12 in the upstream direction of the cylinder 21 (leftward in FIG. 4) over the entire stroke.

  In the present embodiment, when the free piston 12 moves in the downstream direction of the cylinder 21 exceeding a predetermined stroke when the brake is operated, the downstream side that communicates the upstream chamber 15 and the downstream chamber 16 facing the outer peripheral portion of the free piston 12. Since the recess 23 and the return spring 45 that urges the free piston 12 in the upstream direction of the cylinder 21 over the entire stroke are provided, the operation that the seal ring 19 returns from the downstream recess 23 to the position in sliding contact with the cylinder 21 is ensured. In addition, the operation of returning the free piston 12 to the initial position where the free piston 12 slides on the cylinder 21 and contacts the upstream retainer 31 is reliably performed.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

Sectional drawing of the adjuster valve which shows embodiment of this invention. Sectional drawing which similarly shows the operating state of a brake device. Sectional drawing of the adjuster valve which shows other embodiment. Sectional drawing of the adjuster valve which shows other embodiment. Sectional drawing which shows the operating state of a brake device as a prior art example. Sectional drawing which similarly shows the operating state of a brake device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Disc rotor 2 Brake caliper 3 Lining 4 Anchor pin 6 Return spring 7 Hydraulic piston 10 Brake hydraulic path 11 Adjuster valve 12 Free piston 13 Downstream side cap 14 Upstream side cap 15 Upstream chamber 16 Downstream chamber 19 Seal ring 21 Cylinder 23 Downstream side recessed part 24 Upstream recess 26 Annular step 29 Annular gap 31 Upstream retainer 32 Relief spring 41 Downstream retainer 42 Return spring 45 Return spring

Claims (4)

A return spring that urges the restrictor away from the disc rotor, a hydraulic piston that presses the restrictor against the disc rotor, a brake hydraulic passage that guides the hydraulic pressure to the hydraulic piston, and a return from the hydraulic piston when the brake is released An adjuster valve for limiting the amount of hydraulic oil, and the adjuster valve includes a cylinder that defines the brake hydraulic pressure passage, and a free piston that is slidably interposed in the cylinder and partitions the upstream chamber and the downstream chamber. In the vehicular brake device for adjusting the brake clearance between the disc rotor and the control wheel by stopping the flow of hydraulic oil in the cylinder when the brake is released,
An upstream recess that communicates the upstream chamber and the downstream chamber against the outer peripheral portion of the free piston as the free piston moves in the upstream direction of the cylinder over a predetermined stroke when the brake is released; A relief spring that urges the free piston in the downstream direction of the cylinder, and the free piston resists the relief spring as the hydraulic pressure in the downstream chamber rises above a predetermined value when the brake is released. The hydraulic brake moves in the upstream direction of the cylinder, and the hydraulic oil in the downstream chamber flows into the upstream chamber through the clearance between the outer peripheral portion of the free piston and the upstream recess. apparatus.   The adjuster valve includes an upstream retainer that abuts the free piston when the brake is released, and a restricting portion that restricts a stroke of the upstream retainer moving in the downstream direction of the cylinder, and the relief spring is the upstream retainer. The vehicle brake device according to claim 1, wherein the vehicle is biased in a direction in which the pressure is pressed against the regulating portion.   When the brake is operated, the free piston moves in a downstream direction of the cylinder beyond a predetermined stroke. A downstream retainer that abuts the free piston that has moved to the downstream end of the cylinder, and a return spring that biases the downstream retainer in the upstream direction of the cylinder. It contacts the downstream retainer and moves in the downstream direction of the cylinder against the return spring, and the hydraulic oil in the upstream chamber flows into the downstream chamber through the clearance between the outer peripheral portion of the free piston and the downstream recess. The vehicle brake device according to claim 1 or 2, wherein the vehicle brake device is configured.   A downstream recess that communicates between the upstream chamber and the downstream chamber as opposed to an outer peripheral portion of the free piston when the free piston moves beyond a predetermined stroke in the downstream direction of the cylinder when the brake is operated; The vehicular brake device according to any one of claims 1 to 3, further comprising a return spring that urges the piston in the upstream direction of the cylinder over the entire stroke.