JP5459493B2 - Disc brake device - Google Patents

Description

  The present invention relates to a disc brake device in which a disc rotor that rotates integrally with a wheel is clamped by a friction pad provided on a caliper so that a braking force is applied to the wheel via the disc rotor by its frictional resistance.

  In a general caliper floating type disc brake device, a caliper arranged so as to straddle the disc rotor is supported by a mounting bracket. The caliper is provided with a pair of slide pins, and the mounting bracket is provided with a fitting hole for slidably fitting the pair of slide pins. Thus, the caliper can move in the direction of the rotation axis of the wheel by sliding the slide pin with respect to the fitting hole. Further, an inner pad (friction pad) is movably supported on one side of the caliper, and an outer pad (friction pad) is fixed on the other side. Further, the caliper is provided with a piston and a cylinder for pressing (crimping) the inner pad against the disk rotor on one side.

  In such a caliper floating type disc brake device, when the driver depresses the brake pedal, the piston supported by the cylinder advances in accordance with the depression force, and the inner pad is pressed (crimped) against the disc rotor. The caliper moves in the direction of the rotational axis of the wheel by the reaction force of the piston moving forward, and presses (compresses) the outer pad against the disk rotor. Thus, the inner pad and the outer pad can sandwich the disc rotor, and a braking force can be applied to the wheel via the disc rotor that rotates integrally with the wheel.

  By the way, the piston provided in the caliper is movably supported by a cylinder formed in the caliper and held fluid-tight by a piston seal, and hydraulic fluid (brake fluid) is formed in a hydraulic chamber formed in the cylinder during braking. ), The piston moves forward while deforming the piston seal, and when the hydraulic pressure is released from the hydraulic chamber (when the pressure is released), the piston moves backward toward the hydraulic chamber due to the restoring force of the deformed piston seal. Is configured to do. However, for example, when the driver's brake pedal depression force is excessive, the piston is pushed toward the disc rotor more than a predetermined amount as the hydraulic pressure in the hydraulic chamber increases, and there is a relative movement between the piston and the piston seal. In some cases, the piston cannot be fully retracted due to the restoring force of the piston seal. In this case, there is a possibility that a phenomenon in which the inner pad or the outer pad keeps in contact with the disk rotor, that is, a so-called drag phenomenon occurs. In addition, when the drag phenomenon occurs in this way, there is a possibility that a so-called knockback occurs in which the inner pad or the outer pad is repelled by the rotating disk rotor and pushes back the piston.

  In order to solve this problem, for example, a disc brake device disclosed in Patent Document 1 below and a disc brake caliper disclosed in Patent Document 2 below are known.

  The disc brake device disclosed in the following Patent Document 1 forms an annular ring mounting groove in an inner hole of a cylinder and forms a chamfered portion on the pad side at an opening edge on the pad side of the ring mounting groove. In addition, a retraction ring that seals the piston and cylinder and returns the piston when the pressure is released after braking is assembled. In addition, an annular recess that opens toward the pad side end wall is formed in the pad side end wall of the ring mounting groove, and the ring of the retraction ring assembled in the ring mounting groove is formed in the annular recess. A deformation-accepting ring made of a compressible material that allows entry deformation into the recess is assembled. As a result, the hydraulic pressure at which the amount of flexure of the pad and cylinder, which increases as the hydraulic pressure increases, becomes larger than the amount of piston retracted by the retraction ring can be set to a higher value. Drag can be reduced to the usage environment that becomes pressure.

  The disc brake caliper disclosed in Patent Document 2 below is provided with a piston seal that frictionally engages with the outer peripheral surface of the piston by a retainer in a large-diameter hole formed in the caliper body, and the retainer is moved in the retracting direction of the piston. A disc spring is provided for biasing. As a result, when the brake fluid pressure is low, the retainer is prevented from advancing by the preload of the disc spring, and the piston seal is elastically deformed into the chamfered portion by the advance of the piston, and the piston is restored by the restoring force of the piston seal when the pressure is released. Retraction can be ensured to prevent the drag phenomenon. On the other hand, when the brake fluid pressure is high, the retainer and piston seal overcome the preload of the disc spring and move forward, so there is no sliding (relative movement) between the piston and piston seal. Retraction can prevent the occurrence of drag phenomenon. Also, when the brake pad is worn, the piston seal is elastically deformed to the allowable limit, and then the piston is allowed to move forward by sliding (relative movement) between the piston and the piston seal, thereby correcting the clearance between the brake pad and the disc rotor. can do.

JP 7-253128 A Japanese Unexamined Patent Publication No. 5-65929

  By the way, in the conventional disc brake device described above, the clearance between the piston and the friction pad (disc rotor) may fluctuate due to pressure history, knockback, pad wear, and the like. The position of the traction ring is not stable, and there is a possibility that the piston cannot be retracted stably. For this reason, even if a drag phenomenon occurs, it is difficult to cancel the drag phenomenon, and even when there is a clearance greater than a specified value between the piston and the pad (disk rotor), it can be corrected to the specified value. It can be difficult.

  In the conventional disc brake caliper, when the brake pad is worn and the brake fluid pressure is high, a relative movement occurs between the piston and the retraction ring, and the piston advances more than the compression amount of the disc spring. There is a possibility that the piston cannot be retracted properly and a pad drag phenomenon may occur.

  That is, in the conventional disc brake device and disc brake caliper, the piston is returned by the piston seal. However, there is a possibility that the piston cannot be sufficiently returned only by the restoring force of the piston seal, and as a result, a pad drag phenomenon may occur.

  In particular, in the conventional disc brake device and disc brake caliper, since the retract mechanism is provided on the outer peripheral side of the piston, the outer dimension of the caliper may be increased. In this case, it is desirable to reduce the size and weight of the caliper body from the viewpoints of good mountability on the vehicle and improved fuel efficiency.

  The present invention has been made to address the above-described problems, and an object of the present invention is to provide a disc brake device that can be reduced in size and weight and that can appropriately return a piston to suppress the occurrence of a pad drag phenomenon. There is to do.

In order to achieve the above object, the present invention is characterized in that a disk rotor that rotates integrally with a wheel around a rotation axis and a friction pad that faces the friction surface of the disk rotor are increased as the brake fluid pressure increases. A caliper having a piston that presses against the friction surface and a cylinder that supports the piston in a fluid-tight manner so that the piston can move forward and backward, and the piston that is housed in the caliper and moves forward to press the friction pad In a disc brake device having a retract mechanism that moves backward as the hydraulic pressure decreases, the retract mechanism is arranged on the inner peripheral side of a piston formed in a cylindrical shape so that the brake hydraulic pressure acts. and a mover moving in forward and backward direction in the same direction of the piston have the being elastically interposed between the inner peripheral surface and the outer peripheral surface of the mover of the piston The mover is caused to follow the piston, and relative movement between the mover and the piston is allowed when a predetermined load is applied to the piston and the mover as the brake fluid pressure increases. and tracking means for being compressed provided on the cylinder by the movement of the movable element, restored to impart a restoring force for restoring deformation due to the compression with decreasing the brake fluid pressure to said movable element It is composed of the force applying means. In this case, the preset predetermined load may be preset according to the magnitude of the frictional force between the inner peripheral surface of the follower and the outer peripheral surface of the mover, for example.

  Further, the cylinder includes a center shaft extending in the advance / retreat direction of the piston on the inner peripheral side of the piston, and the mover is on the outer peripheral surface of the center shaft in the same direction as the advance / retreat direction of the piston. The restoring force applying means moves following the advance of the piston and the elastic member provided on the proximal end side of the center shaft, the stopper formed on the distal end side of the center shaft. It is good to comprise with the highly elastic member compressed by the said needle | mover. In this case, the piston is formed, for example, in a bottomed cylindrical shape, and the center shaft and the mover pass through a through hole formed in the bottom surface of the piston. The follow-up means may be elastically mounted between an inner peripheral surface of a through hole formed in the bottom surface of the piston and an outer peripheral surface of the mover passing through the through hole. Furthermore, the center shaft may be assembled integrally with the cylinder, for example.

  Further, the follow-up means, for example, when the mover follows the advance of the piston as the brake fluid pressure increases, and moves integrally with the mover, is one of the piston and the mover. When the forward movement is inhibited, the other of the piston and the mover is allowed to move forward, and the restoring force applied to the movable element by the restoring force applying means as the brake fluid pressure decreases. The piston and the mover may be moved backward integrally. More specifically, the follow-up means, for example, when the mover follows the advance of the piston as the brake hydraulic pressure increases, moves the piston integrally with the friction pad. When the friction pad is pressed against the friction surface of the disk rotor and the advance of the piston is impeded, the mover may be allowed to advance.

  According to these, the retract mechanism can be provided on the inner peripheral side of the cylindrically formed piston, and the advanced piston can be reliably returned. That is, in the retract mechanism provided on the inner peripheral side of the piston, the mover can follow the advance of the piston by the follower. The mover can advance, for example, by compressing restoring force applying means (specifically, a highly elastic member) on the outer peripheral surface of the center shaft.

  Further, in a situation where the movement of the piston or the mover is hindered when the brake fluid pressure is increased, a predetermined load, specifically, the friction between the inner peripheral surface of the follower and the outer peripheral surface of the mover When a load larger than the force is applied, the follower can allow relative movement of the piston or the mover whose movement is not hindered. And even if it is a case where it moves relatively in this way, a needle | mover can compress a restoring force provision means.

  As a result, the compressed restoring force applying means can apply a restoring force to the mover, so that at the time of depressurization, the mover moves the piston that has advanced to press the friction pad by this restoring force. An appropriate amount can be returned integrally through the follow-up means. Therefore, the distance (clearance) between the piston and the friction pad (disk rotor) can be appropriately secured, and as a result, the occurrence of the friction pad drag phenomenon can be suppressed and a stable brake feeling can be obtained. it can.

  Moreover, since the retract mechanism can be provided on the inner peripheral side of the piston, the outer dimension of the caliper, more specifically, the inner diameter of the cylinder can be reduced, and the weight can be reduced. Furthermore, since the mover of the retract mechanism can be arranged on the inner peripheral side of the piston to reduce the inner diameter of the cylinder, the brake fluid pressure is preferentially and efficiently applied to the pressure receiving portion of the piston. You can also.

1 is a schematic view of a disc brake device according to an embodiment of the present invention. FIG. 2 is an enlarged schematic view for explaining the retract mechanism of FIG. 1. It is a figure for demonstrating the case where the piston of FIG. 2 and a needle | mover advance without a relative movement. It is a figure for demonstrating the case where the piston of FIG. 2 moves relatively with respect to a needle | mover, and moves forward. It is a graph for demonstrating the relationship of the stroke amount of the piston with respect to brake fluid pressure. It is a figure for demonstrating the case where the needle | mover of FIG. 2 moves relative to a piston and moves forward.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 schematically shows a caliper floating disc brake device according to an embodiment of the present invention.

  This disc brake device is provided along a rotation axis direction of the disc rotor 11 by a disc rotor 11 that rotates around a rotation axis of an axle integrally with a wheel (not shown), and a mounting bracket (not shown) fixed to the vehicle body side. The caliper 12 is movably supported.

  The caliper 12 has a substantially U-shaped cross section so as to straddle the disc rotor 11, and a cylinder portion 13 to which brake fluid is supplied according to a brake operation by the driver, and the cylinder portion 13 and the disc rotor 11 are connected to each other. It is comprised from the nail | claw part 14 arrange | positioned in the position which opposes via, and the connection part 15 which connects the cylinder part 13 and the nail | claw part 14. As shown in FIG. The cylinder part 13 supports the piston 16 so as to be able to advance and retract. The piston 16 is formed in a bottomed cylindrical shape, and an annular seal groove 16a is formed on the outer peripheral surface thereof. The seal groove 16a accommodates a first seal member (for example, lip packing) 16a1 that prevents leakage of brake fluid from the inner peripheral surface of the cylinder portion 13 and has a small sliding resistance (friction resistance). Has been.

  Further, a through-hole 16c is formed in a substantially central portion of the pressure receiving surface 16b that is the bottom surface of the piston 16. The through hole 16c has a center shaft 17 integrally fixed to the bottom surface 13a of the cylinder portion 13 so as to extend in the advancing and retracting direction of the piston 16, and an outer peripheral surface of the center shaft 17. The retraction mechanism 20 which exhibits the retract function assembled in is penetrated in a liquid-tight manner. For this reason, an annular seal groove 16c1 is formed on the inner peripheral surface of the through hole 16c, and brake fluid leaks between the seal groove 16c1 and the outer peripheral surface of the mover 21 of the retract mechanism 20 described later. And a second seal member (for example, an O-ring) 16c2 as a follow-up means of the present invention is accommodated. Here, the first seal member 16b and the second seal member 16c2 define a hydraulic pressure chamber 13b in the cylinder portion 13 that is filled with the brake fluid whose pressure has been adjusted. The frictional force between the second seal member 16c2 and the outer peripheral surface of the retract mechanism 20 is set to be larger than the frictional force between the first seal member 16a1 and the inner peripheral surface of the cylinder part 13. ing.

  The caliper 12 is assembled with a pair of friction pads 18 and 19 that face the friction surfaces on both sides of the disc rotor 11. The friction pads 18 and 19 are disposed on the cylinder part 13 side and the claw part 14 side of the caliper 12, respectively. In the following description, the friction pad 18 disposed on the cylinder part 13 side of the caliper 12 and pressed by the piston 16 is referred to as an inner pad 18, and the friction pad 19 disposed on the claw part 14 side is referred to as an outer pad 19. . Although detailed description is omitted, the inner pad 18 and the outer pad 19 are configured such that the base ends of the friction materials 18a and 19a are fixed to the back plates 18b and 19b.

  As shown in an enlarged view in FIG. 2, the retract mechanism 20 is assembled on the outer peripheral surface of the center shaft 17 between the bottom surface 13 a of the cylinder portion 13 and a stopper 17 a formed at the tip portion of the center shaft 17. ing. The retract mechanism 20 includes a mover 21 that can move forward and backward in the same direction as the piston 16 by a frictional force generated by the second seal member 16c2 as a follower, and a mover 21 and a stopper 17a (the tip side of the center shaft 17). ) And a ring-shaped second elastic member disposed between the movable element 21 and the bottom surface 13a (the base end side of the center shaft 17). ing.

  The mover 21 is formed in a cylindrical shape (sleeve shape). The mover 21 can freely advance and retreat in the axial direction of the center shaft 17, that is, in the front-rear axial direction of the piston 16.

  The first elastic member 22 is accommodated in an annular accommodating step portion 21 a formed from a highly elastic material (for example, rubber material) and formed on the distal end side of the mover 21. When the first elastic member 22 is compressed and elastically deformed by the inner peripheral surface of the accommodating step portion 21a of the movable element 21 and the stopper 17a, the first elastic member 22 generates an elastic force (restoring force) corresponding to the elastic deformation. 21 is given. The first elastic member 22 may be an O-ring having a substantially O-shaped cross section or a D-ring having a substantially D-shaped cross section that is not shown.

  When the second elastic member 23 is molded from an elastic material (for example, a rubber material) and is compressed and elastically deformed by the proximal end surface of the movable element 21 and the bottom surface 13a of the cylinder portion 13, the second elastic member 23 is subjected to this elastic deformation. A corresponding elastic force (restoring force) is applied to the mover 21. As the second elastic member 23, an O-ring having a substantially O-shaped cross section or a D-ring having a substantially D-shaped cross section not shown can be used.

  In the retract mechanism 20 configured as described above, the mover 21 follows the piston 16 on the outer peripheral surface of the center shaft 17 by the frictional force of the second seal member 16c2 accommodated in the seal groove 16c1 of the piston 16. Slide The mover 21 is disposed between the first elastic member 22 and the second elastic member 23 having elasticity on the outer peripheral surface of the center shaft 17. That is, as shown in FIG. 2, the first elastic member 22 is in contact with the distal end side of the movable element 21 (more specifically, the accommodation step portion 21 a formed on the distal end side) and the stopper 17 a of the center shaft 17. It arrange | positions and the 2nd elastic member 23 is arrange | positioned so that the base end side of the needle | mover 21 and the bottom face 13a of the cylinder part 13 may be contacted. In the following description, as shown in FIG. 2, the sliding position of the movable element 21 when the first elastic member 22 and the second elastic member 23 are in contact with the movable element 21, the stopper 17a, and the bottom surface 13a. Is called in-situ.

  Therefore, when the mover 21 slides forward from the original position following the advance of the piston 16 in the direction of pressing the inner pad 18, the first elastic member 22 is compressed between the mover 21 and the stopper 17a. And elastically deforms. Thereby, the first elastic member 22 can apply an elastic force (restoring force) corresponding to the sliding amount of the movable element 21, in other words, the compression amount, to the movable element 21. Here, when the mover 21 slides following the advance of the piston 16, the slide amount from the original position of the mover 21 is the maximum elastic deformation amount of the first elastic member 22 (or the tip of the accommodation step portion 21 a). The contact with the stopper 17a). That is, the slide amount of the mover 21 that is regulated by the maximum elastic deformation amount of the first elastic member 22 corresponds to the return amount (retract amount) for returning the piston 16. The restoring force applied to the mover 21 from the first elastic member 22 is transmitted to the piston 16 via the second seal member 16c2 that is in contact by a large frictional force, so that the restoring force is separated from the inner pad 18. It acts as a return force for moving the piston 16 backward.

  On the other hand, when this return force is applied, the mover 21 slides backward (that is, in the original position direction). Further, the movable element 21 is moved in the original position direction, that is, in the second position by the external force input to the piston 16 through the inner pad 18 due to the displacement (inclination) of the disc rotor 11 in the rotation axis direction when the vehicle turns. There is a case where it slides toward the elastic member 23.

  Here, since the 2nd elastic member 23 is shape | molded from an elastic material, if it compresses between the needle | mover 21 and the bottom face 13a and elastically deforms, an elastic force (restoring force) will be provided with respect to the needle | mover 21. be able to. Therefore, the mover 21 is returned to the original position by the elastic force (restoring force) applied from the first elastic member 22 and the elastic force (restoring force) applied from the second elastic member 23.

  Next, the operation of the disc brake device according to the first embodiment configured as described above will be described. In the disc brake device, when the brake fluid is supplied to the cylinder portion 13 of the caliper 12 and the pressure in the hydraulic pressure chamber 13b of the cylinder portion 13 is increased, the piston 16 advances toward the disc rotor 11 and the piston 16 moves forward. 16 presses the inner pad 18 and presses against the friction surface of the disk rotor 11. At this time, the caliper 12 moves in the opposite direction to the piston 16 due to the reaction caused by the forward movement of the piston 16, and presses the outer pad 19 assembled to the claw portion 14 against the friction surface of the disc rotor 11. As a result, a frictional resistance force is generated between the inner pad 18 and the outer pad 19 and the rotating disk rotor 11, and a braking force can be applied to the disk rotor 11, that is, the wheels.

  On the other hand, when the brake fluid is discharged from the cylinder portion 13 of the caliper 12 and the pressure in the hydraulic chamber 13b of the cylinder portion 13 is reduced, the piston 16 moves backward in the direction away from the disk rotor 11 and the inner pad. 18 is separated from the friction surface of the disk rotor 11. At this time, the caliper 12 moves in the opposite direction to the piston 16 due to the reaction caused by the retreat of the piston 16, and the outer pad 19 assembled to the claw portion 14 is separated from the friction surface of the disc rotor 11.

  By the way, with respect to such forward and backward movement of the piston 16, the retract mechanism 20 of the caliper 12 corresponds to the magnitude of the pressure in the hydraulic chamber 13b and the wear state of the inner pad 18 (and the outer pad 19). Follow the piston 16 and return the piston 16. Hereinafter, the operation of the retract mechanism 20 will be described in detail.

  First, the case where the pressure in the hydraulic chamber 13b during pressurization is low will be described. In this case, as shown in FIG. 3, when the piston 16 moves forward in accordance with an increase in the pressure in the hydraulic pressure chamber 13b, the mover 21 is moved against the advance of the piston 16 by the frictional force generated by the second seal member 16c2. Follow without causing relative movement. Thereby, the mover 21 slides on the outer peripheral surface of the center shaft 17 toward the first elastic member 22. And the needle | mover 21 compresses the 1st elastic member 22 with the stopper 17a. At this time, since the pressure in the hydraulic chamber 13b is low, the first elastic member 22 is elastically deformed to an elastic deformation amount that is less than the maximum elastic deformation amount, and a restoring force corresponding to the elastic deformation amount is applied to the mover. 21. In this state, when the pressure in the hydraulic chamber 13 b is released, the movable element 21 is returned to the original position by the restoring force of the first elastic member 22 and the second sealing member 16 c 2 is restored to the piston 16. To communicate. As a result, the piston 16 is returned by a retract amount corresponding to the elastic deformation amount of the first elastic member 22.

  Next, when the pressure in the hydraulic chamber 13b during pressurization is high, as shown in FIG. 3, the mover 21 follows the forward movement of the piston 16 without causing relative movement. The first elastic member 22 is elastically deformed until the maximum elastic deformation amount is reached. In this state, when the pressure in the hydraulic chamber 13 b is released, the movable element 21 is returned to the original position by the restoring force of the first elastic member 22 and the second sealing member 16 c 2 is restored to the piston 16. To communicate. As a result, the piston 16 is returned by a retract amount corresponding to the maximum elastic deformation amount of the first elastic member 22.

  Further, when the pressure in the hydraulic chamber 13b during pressurization is excessive, for example, a back plate 18b forming the inner pad 18 or a spacer (shim plate) provided between the end of the piston 16 and the back plate 18b. ) Or the cylinder portion 13 or the like, the amount of advancement of the piston 16 increases beyond a predetermined level. In this case, in a situation where the first elastic member 22 is elastically deformed to the maximum elastic deformation amount (or a situation where the accommodation step portion 21a of the movable element 21 and the stopper 17a are in contact), the piston 16 follows the forward movement. Therefore, the mover 21 cannot slide on the outer peripheral surface of the center shaft 17. Therefore, in this case, as shown in FIG. 4, the forward force (load) for moving the piston 16 forward by the brake hydraulic pressure is the frictional force between the second seal member 16 c 2 and the outer peripheral surface of the mover 21 ( That is, when it becomes larger than the predetermined load), the piston 16 moving forward and the mover 21 move relative to each other. However, in this state, when the pressure in the hydraulic chamber 13b is released, the movable element 21 returns to the original position by the restoring force of the first elastic member 22, and the second seal member 16c2 is moved against the piston 16. Transmits restoring force. As a result, the piston 16 is returned by a retract amount corresponding to the maximum elastic deformation amount of the first elastic member 22.

  Thus, the retract mechanism 20 can return the piston 16 by a predetermined retract amount according to the pressure in the hydraulic chamber 13b. Here, the pressure in the hydraulic chamber 13b of the cylinder part 13, that is, the advance amount of the piston 16 with respect to the brake hydraulic pressure will be described with reference to FIG. As shown by the solid line in FIG. 5, when the amount of advancement of the piston increases as the brake fluid pressure increases, the conventional disc brake device that does not include the retract mechanism 20 is shown by the one-dot chain line in FIG. As described above, the piston retract amount (return amount) due to the seal retract increases at the initial time and exceeds the piston advance amount. However, since the relative movement between the piston seal and the piston occurs at an early stage, the subsequent retract amount (return amount) does not increase and falls below the advance amount of the piston.

  On the other hand, in the disc brake device of this embodiment provided with the retract mechanism 20, until the first elastic member 22 is elastically deformed to the maximum elastic deformation amount (or the accommodation step portion 21a of the movable element 21 and the stopper 17). The movable element 21 can slide following the advance amount of the piston 16 (so-called stroke absorbing function) until the contact is made. Therefore, as shown by a broken line in FIG. 5, the retract amount (return amount) of the piston 16 by the retract mechanism 20 continuously increases from the initial time, and exceeds the advance amount of the piston 16 in the entire region. . Therefore, since the piston 16 is returned by a predetermined retract amount depending on the pressure over the entire hydraulic pressure region, the occurrence of the drag phenomenon of the inner pad 18 and the outer pad 19 can be suppressed, and a stable brake fee can be obtained. You can get a ring.

  Next, an operation in which the retract mechanism 20 follows the piston 16 and returns the piston 16 in accordance with the wear state of the inner pad 18 (and the outer pad 19) will be described. First, the case where the wear of the inner pad 18 is large will be described. When the wear of the inner pad 18 (more specifically, the wear of the friction material 18a) is large, the distance (clearance) between the inner pad 18 and the outer pad 19 and the disk rotor 11 becomes large. In this case, in order to press the inner pad 18 against the friction surface of the disk rotor 11, the advance amount of the piston 16 that advances according to the pressure in the hydraulic chamber 13 b of the cylinder portion 13 increases.

  For this reason, in the retract mechanism 20, when the piston 16 moves forward in accordance with the increase in pressure in the hydraulic chamber 13b, the mover 21 does not move relative to the advance of the piston 16 as described above. It follows and slides on the outer peripheral surface of the center shaft 17 toward the first elastic member 22. Then, the mover 21 elastically deforms the first elastic member 22 with the stopper 17a until, for example, the maximum elastic deformation amount is reached. In this state, if the piston 16 has not yet pressed the inner pad 18, the piston 16 further moves forward, so that the movable element 21 cannot slide following the advancement of the piston 16. That is, in this case, as shown in FIG. 4, the advancing force (load) for advancing the piston 16 by the brake fluid pressure is the frictional force between the second seal member 16 c 2 and the outer peripheral surface of the mover 21. When the pressure is larger than the predetermined load (ie, the predetermined load), the piston 16 and the mover 21 move relative to each other, and the piston 16 presses the inner pad 18 by the forward movement accompanied by the relative movement, so that the friction surface of the disk rotor 11 and Generate frictional resistance.

  When the pressure in the hydraulic chamber 13b is removed, the movable element 21 and the piston 16 that moves relative to each other are integrated by the elastic force (restoring force) of the first elastic member 22 that is elastically deformed to the maximum elastic deformation amount. Therefore, it retracts by the retract amount corresponding to the maximum elastic deformation amount. As a result, the inner pad 18 (and the outer pad 19) is returned to a position having a predetermined clearance with the disk rotor 11, so that the drag phenomenon of the inner pad 18 and the outer pad 19 can be suppressed and stable. Brake feeling can be obtained.

  On the other hand, when the worn inner pad 18 (and outer pad 19) is replaced with a new inner pad 18 (and outer pad 19), for example, the distance between the inner pad 18 and the disk rotor 11 ( (Clearance) decreases. In this case, in order to press the inner pad 18 against the friction surface of the disk rotor 11, the advance amount of the piston 16 that advances according to the pressure in the hydraulic chamber 13 b of the cylinder portion 13 decreases.

  For this reason, in the retract mechanism 20, when the piston 16 moves forward in accordance with the increase in pressure in the hydraulic chamber 13b, the mover 21 does not move relative to the advance of the piston 16 as described above. It follows and slides on the outer peripheral surface of the center shaft 17 toward the first elastic member 22. Then, before the first elastic member 22 is elastically deformed to the maximum elastic deformation amount by the sliding of the mover 21, the piston 16 stops when the piston 16 presses the inner pad 18 and presses against the disk rotor 11. However, even when the piston 16 stops moving forward, if the pressure in the hydraulic pressure chamber 13b is maintained at a high level, the mover 21 resists the frictional force generated by the second seal member 16c2 by the brake hydraulic pressure. Further advance in the direction of the first elastic member 22 to press the first elastic member 22. That is, in this state, as shown in FIG. 6, the forward force (load) acting on the mover 21 due to the brake fluid pressure is a frictional force between the second seal member 16 c 2 and the outer peripheral surface of the mover 21 (that is, , The movable element 21 moves relative to the piston 16 and further elastically deforms the first elastic member 22 to the maximum elastic deformation amount, for example.

  When the pressure in the hydraulic chamber 13b is released, the movable element 21 and the piston 16 that are relatively moved are integrally elastically elastically deformed by the elastic force (restoring force) of the elastically deformed first elastic member 22. Retreat by a retract amount corresponding to the amount. As a result, the inner pad 18 and the outer pad 19 are returned to a position having a predetermined clearance with the disk rotor 11, so that the drag phenomenon of the inner pad 18 and the outer pad 19 can be suppressed and a stable brake can be achieved. Feeling can be obtained.

  As can be understood from the above description, according to the disc brake device of this embodiment, the retract mechanism 20 is provided on the inner peripheral side of the piston 16, and the advanced piston 16 can be reliably returned. That is, in the retract mechanism 20 provided on the inner peripheral side of the piston 16, the movable element 21 is caused by the frictional force between the second seal member 16 c 2 as the follower and the movable element 21 with respect to the advance of the piston 16. Can follow. The mover 21 can advance on the outer peripheral surface of the center shaft 17 by compressing the first elastic member 22 as restoring force applying means.

  Further, in a situation where the movement of the piston 16 or the mover 21 is hindered when the pressure in the hydraulic chamber 13b is increased, a load larger than the frictional force between the second seal member 16c2 and the mover 21 is obtained. When the act acts, the movable piston 16 or the movable element 21 can move forward with relative movement. And even if it is a case where it moves relatively in this way, the needle | mover 21 can compress the 1st elastic member 22. FIG.

  Thereby, since the compressed 1st elastic member 22 can give a restoring force with respect to the needle | mover 21, the needle | mover 21 pushes forward piston 16 in order to press the inner pad 18 with this restoring force. An appropriate amount can be integrally returned via the second seal member 16c2. Therefore, the distance (clearance) between the inner pad 18 and the outer pad 19 and the disk rotor 11 can be appropriately ensured, and as a result, the occurrence of a dragging phenomenon of the friction pad can be suppressed and a stable brake feeling can be obtained. be able to.

  Further, since the retract mechanism 20 can be provided on the inner peripheral side of the piston 16, the outer dimension of the caliper 12, more specifically, the inner diameter of the cylinder part 13 can be reduced, and the weight can be reduced. it can. Furthermore, since the movable element 21 of the retract mechanism 20 can be arranged on the inner peripheral side of the piston 16 to reduce the inner diameter of the cylinder portion 13, it can be preferentially and efficiently used with respect to the pressure receiving portion 16b of the piston 16. Brake fluid pressure can also be applied.

  The implementation of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the object of the present invention.

  For example, in the above embodiment, the retract mechanism 20 is applied to a caliper floating type disc brake device that presses only the inner pad 18 with the piston 16. In this case, it is also possible to employ a caliper-fixed disc brake device having a piston that presses the inner pad and the outer pad individually. In this case, the same effect as that of the above embodiment can be obtained by providing a retract mechanism configured similarly to the above embodiment for each of the pistons that press the inner pad and the outer pad.

DESCRIPTION OF SYMBOLS 11 ... Disc rotor, 12 ... Caliper, 13 ... Cylinder part, 13a ... Caliper seal groove, 13b ... Hydraulic pressure chamber, 16 ... Piston, 16c2 ... Second seal member, 17 ... Inner pad, 18 ... Outer pad, 20 ... Retract mechanism , 21 ... mover, 22 ... first elastic member, 23 ... second elastic member

Claims (7)

A disk rotor that rotates integrally with the wheel around the rotational axis, and a piston that presses the friction pad facing the friction surface of the disk rotor toward the friction surface as the brake fluid pressure increases, and the piston A caliper having a cylinder that is densely supported so as to be able to advance and retreat, and a retract mechanism that retracts the piston, which is accommodated in the caliper and moves forward to press the friction pad, as the brake fluid pressure decreases. Disc brake device
The retract mechanism is disposed on the inner peripheral side of a cylindrical piston,
A mover adapted to act on the brake fluid pressure and moving in the same direction as the piston reciprocating direction;
It is elastically mounted between the inner peripheral surface of the piston and the outer peripheral surface of the mover to cause the mover to follow the piston, and in advance to the piston and the mover as the brake fluid pressure increases. Follow-up means for allowing relative movement between the mover and the piston when a set predetermined load is applied,
Is compressed by the movement of the movable element provided on said cylinder, a restoring force for restoring deformation due to the compression with decreasing the brake fluid pressure from the resilience applying means for applying to said movable element A disc brake device characterized by comprising. In the disc brake device according to claim 1,
The cylinder includes a center shaft that extends in the forward and backward direction of the piston on the inner peripheral side of the piston,
The mover moves on the outer peripheral surface of the center shaft in the same direction as the piston reciprocating direction,
The restoring force applying means is compressed by an elastic member provided on the proximal end side of the center shaft, a stopper formed on the distal end side of the center shaft, and the mover that moves following the advance of the piston. A disc brake device comprising a highly elastic member. In the disc brake device according to claim 1,
The following means is
When the mover follows the advance of the piston as the brake fluid pressure increases, and the advance of one of the piston and the mover is inhibited, the piston And allowing the other of the movers to advance,
The disc brake device according to claim 1, wherein the piston and the mover are integrally moved backward by the restoring force applied to the mover by the restoring force applying unit as the brake fluid pressure decreases. In the disc brake device according to claim 3,
The following means is
As the brake fluid pressure increases, the mover follows the advance of the piston and advances integrally, so that the piston presses the friction pad, and the friction pad causes the friction of the disk rotor. A disc brake device, wherein the movable member is allowed to advance when the piston is pressed against the surface and the advance of the piston is inhibited. In the disc brake device according to claim 1,
The predetermined load set in advance is
2. A disc brake device according to claim 1, wherein the disc brake device is preset according to a magnitude of a frictional force between an inner peripheral surface of the follower and an outer peripheral surface of the mover. In the disc brake device according to claim 2,
The piston is formed in a bottomed cylindrical shape,
The center shaft and the mover pass through a through hole formed in the bottom surface of the piston,
The disc brake device according to claim 1, wherein the follow-up means is elastically mounted between an inner peripheral surface of a through hole formed in a bottom surface of the piston and an outer peripheral surface of the mover passing through the through hole. In the disc brake device according to claim 2,
A disc brake device in which the center shaft is integrally assembled with the cylinder.

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