JP7253404B2 - vehicle disc brake - Google Patents

Description

The present invention relates to a vehicle disc brake, and more particularly, a vehicle in which a piston is liquid-tightly inserted into a cylinder hole provided in a caliper body via a piston seal, and the piston is rolled back by the piston seal when braking is released. for disc brakes.

Conventionally, in vehicle disc brakes, the piston is liquid-tightly inserted into a cylinder hole provided in the caliper body via a piston seal. There has been a technique in which the amount of rollback of the piston is adjusted by changing the shape of the seal groove into which the piston is fitted (see, for example, Patent Documents 1 and 2).

Japanese Patent No. 4126428 Japanese Patent No. 5327703

However, in the case of changing the shape of the piston seal and the shape of the seal groove as in the above-mentioned Patent Documents 1 and 2, the shape of the piston seal formed in an annular shape with a rubber-like elastic material is changed, and the narrow seal groove is processed. was costly. Also, if the shape of the piston seal or the seal groove is changed, there is a risk that the operational feeling will change significantly.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a vehicle disc brake in which the amount of rollback of a piston can be easily and accurately adjusted without changing the shape of the piston seal or seal groove.

In order to achieve the above object, a vehicle disc brake according to the present invention has a seal groove for fitting a piston seal in a cylinder hole provided in a caliper body. A vehicular disc brake in which a bottomed cylindrical piston that presses is inserted with an opening toward the friction pad side and a hydraulic pressure chamber is defined between the piston and the cylinder hole, wherein the piston: From the new state of the friction pad to the specified full wear state, the seal area on the piston opening side that contacts the piston seal, and the friction pad from the new state to the specified full wear state, A non-sealing area on the bottom side of the piston that does not abut on the piston seal is provided, and a liquid chamber is defined between the outer peripheral wall of the non-sealing area of the piston and the cylinder hole so as to be continuous with the hydraulic pressure chamber. It is characterized by

In addition, it is preferable that at least part of the outer peripheral wall of the non-sealing area of the piston is formed with a conical surface that gradually decreases in diameter toward the bottom of the piston. is preferably formed with a concave circular arc surface. Also, the piston may have a cutout at least part of the outer peripheral wall of the non-sealing area.

Further, it is preferable that at least a portion of the inner peripheral wall of the cylinder hole corresponding to the non-sealing area of the piston is formed with a conical surface that gradually increases in diameter toward the bottom of the cylinder hole. Preferably, at least a portion of the inner peripheral wall corresponding to the non-sealing area of the piston is formed with a concave arcuate surface. Furthermore, the cylinder hole may be formed by cutting out at least a portion of the inner peripheral wall corresponding to the non-sealing area of the piston.

The applicant defined a fluid chamber continuous with the fluid pressure chamber between the outer peripheral wall of the non-sealed area of the piston and the cylinder hole, thereby creating a differential pressure between the fluid chamber and the fluid pressure chamber during braking. It has been confirmed that the amount of rollback of the piston is set according to the time it takes for the pressures in the fluid chamber and the fluid pressure chamber to equalize when braking is released.

For example, increasing the volume of the fluid chamber reduces the differential pressure between the fluid pressure chamber and the fluid chamber during braking, shortening the time until the pressures of the fluid pressure chamber and the fluid chamber become equal when braking is released. As a result, the duration of the sliding frictional force exerted by the piston seal on the piston is shortened, and the rollback amount of the piston is reduced. Further, when the volume of the fluid chamber is reduced, the differential pressure between the fluid pressure chamber and the fluid chamber during braking increases, and the time until the pressures of the fluid pressure chamber and the fluid chamber become equal when braking is released becomes longer. As a result, the duration of the sliding frictional force exerted by the piston seal on the piston is lengthened, and the rollback amount of the piston is increased.

As a result, in the vehicle disc brake of the present invention, the fluid chamber continuous with the fluid pressure chamber is formed between the outer peripheral wall of the non-sealing region of the piston and the cylinder hole without changing the shape of the piston seal or the seal groove. By defining and changing the volume of the liquid chamber, the rollback amount of the piston can be adjusted with high accuracy. In addition, since the piston seal is in sliding contact with the outer peripheral surface of the piston from when the friction pad is brand new to when it reaches the specified full wear state, the sealing performance of the piston is not impaired.

Further, at least a portion of the outer peripheral wall of the non-sealed area of the piston is formed with a conical surface that gradually decreases in diameter toward the bottom of the piston, so that a fluid chamber is formed between the conical surface and the cylinder hole. defined. Also, by changing the angle and length of the conical surface, the rollback amount of the piston can be adjusted with high accuracy. Furthermore, since the volume of the liquid chamber is increased between the piston bottom side and the cylinder hole, even if the piston tilts, the contact noise generated by the contact between the piston bottom side and the cylinder hole (judder) can be suppressed.

At least part of the outer peripheral wall of the non-sealed area of the piston is formed with an arcuate surface that is concave toward the bottom of the piston, so that a fluid chamber is defined between the arcuate surface and the cylinder hole. be. Further, by changing the depth and length of the arc surface, the rollback amount of the piston can be adjusted with high accuracy.

Furthermore, the piston has a notch in at least part of the outer peripheral wall of the non-sealing area, so that a liquid chamber is defined between the notch and the cylinder hole. Further, by changing the size and number of notches, the rollback amount of the piston can be adjusted with high accuracy.

Further, at least a portion of the inner peripheral wall of the cylinder hole corresponding to the non-sealing area of the piston is formed with a conical surface that gradually increases in diameter toward the bottom of the cylinder hole. A liquid chamber is defined between the outer peripheral wall. Also, by changing the angle and length of the conical surface, the rollback amount of the piston can be adjusted with high accuracy. Furthermore, since the volume of the liquid chamber is increased between the piston bottom side and the cylinder hole, even if the piston tilts, the contact noise generated by the contact between the piston bottom side and the cylinder hole (judder) can be suppressed.

At least a portion of the inner peripheral wall of the cylinder hole corresponding to the non-sealing area of the piston is formed with a concave arcuate surface, so that a fluid chamber is defined between the arcuate surface and the outer peripheral wall of the piston. be. Further, by changing the depth and length of the arc surface, the rollback amount of the piston can be adjusted with high accuracy.

Furthermore, the cylinder hole is formed by cutting out at least part of the inner peripheral wall corresponding to the non-sealing area of the piston, so that a liquid chamber is defined between the cutout and the outer peripheral wall of the piston. Further, by changing the size and number of notches, the rollback amount of the piston can be adjusted with high accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional front view of a vehicle disc brake showing a first embodiment of the present invention; It is similarly a partial cross section front view of a piston. It is also a partial cross-sectional perspective view of a piston. FIG. 2 is a cross-sectional front view of a vehicle disc brake showing a second embodiment of the present invention; It is similarly a partial cross section front view of a piston. It is also a partial cross-sectional perspective view of a piston. FIG. 10 is a cross-sectional front view of a vehicle disc brake showing a third embodiment of the present invention; It is similarly a partial cross section front view of a piston. It is also a partial cross-sectional perspective view of a piston. FIG. 11 is a cross-sectional front view of a vehicle disc brake showing a fourth embodiment of the present invention; It is a cross-sectional front view of a vehicle disc brake showing a fifth embodiment of the present invention. It is a cross-sectional front view of a vehicle disc brake showing a sixth embodiment of the present invention. 13 is a cross-sectional view taken along line XIII-XIII of FIG. 12; FIG.

1 to 3 are diagrams showing a first embodiment of a vehicle disc brake according to the present invention. A vehicle disc brake 1 has an action portion 3a and a reaction portion 3b arranged opposite to each other with a disc rotor 2 interposed therebetween. The caliper body 3, which is integrally connected to the bridge portion 3c that straddles the outside of the rotor 2, is attached to the caliper bracket 4 that is fixed to the vehicle body at one side of the disc rotor 2 via a slide pin (not shown). It is supported so as to be movable in the direction. A pair of friction pads 5, 5 are disposed facing each other with the disk rotor 2 interposed between the action portion 3a and the reaction portion 3b.

The action portion 3a of the caliper body 3 is provided with a bottomed cylinder hole 3d that opens toward the disk rotor 2, and the reaction portion 3b has a reaction claw 3e that pushes the friction pad 5 on the reaction portion side. is provided. A bottomed cylindrical piston 6 that presses the friction pad 5 on the working portion side is inserted into the cylinder hole 3d with the opening facing the friction pad side. An annular dust seal mounting groove 3f is formed on the inner peripheral surface of the opening side of the cylinder hole 3d, and an annular piston seal mounting groove 3g is formed on the bottom side of the cylinder hole from the dust seal mounting groove 3f. A piston seal 7 is mounted in the piston seal mounting groove 3g so as to liquid-tightly and movably slide on the outer peripheral surface of the piston 6, and rolls back the piston 6 by its restoring force. A dust seal 8 is attached to prevent dust from entering inside. A hydraulic pressure chamber 9 is defined between the piston 6 and the bottom of the cylinder hole 3d, and pressurized hydraulic fluid is supplied to the hydraulic pressure chamber 9 through the union hole 3h.

Each friction pad 5 comprises a lining 5a that slides on the side surface of the disc rotor 2 and a metal back plate 5b that holds the lining 5a.

When the friction pad 5 is brand new, the piston 6 has a seal area S1 on the piston opening side that contacts the piston seal 7 and the lining 5a has a non-sealing area S2 on the piston bottom side that does not come into contact with the piston seal 7 until the full wear state is reached, and the outer peripheral wall of the non-sealing area S2 gradually decreases toward the piston bottom side. It is formed with a conical surface 6a that becomes As a result, a fluid chamber 9a, which is continuous with the fluid pressure chamber 9, is defined between the conical surface 6a and the cylinder hole 3d.

In the vehicle disc brake 1 formed as described above, when the hydraulic pressure chamber 9 of the caliper body 3 is supplied with pressurized hydraulic fluid through the union hole 3h by the driver's braking operation, the piston 6 is pushed into the cylinder. The friction pad 5 on the working portion side is pushed by moving forward through the hole 3 d in the opening direction, and the lining 5 a of the friction pad 5 is pressed against one side surface of the disk rotor 2 . Next, due to this reaction, the caliper body 3 moves toward the action portion guided by the slide pin, the reaction claw 3e pushes the friction pad 5 on the reaction portion side, and the lining 5a of the friction pad 5 moves to the disk. The other side surface of the rotor 2 is pressed. As a result, a braking force acts on the disc rotor 2 . When the brake is released, the piston 6 rolls back due to the restoring force of the piston seal 7 and retreats in the cylinder hole 3d. move away from

The amount of rollback of the piston 6 is set by the shape of the piston seal mounting groove 3g and the shape of the piston seal 7, and the differential pressure between the fluid chamber 9a and the fluid pressure chamber 9 generated during braking is determined by the braking release. It is set according to the time until equal to time. For example, if the volume of the fluid chamber 9a is increased, the differential pressure between the fluid chamber 9a and the fluid pressure chamber 9 during braking will decrease, and the time required for the pressures in the fluid chamber 9a and the fluid pressure chamber 9 to equalize when braking is released. becomes shorter. As a result, the duration of the sliding frictional force exerted by the piston seal 7 on the piston 6 is shortened, and the rollback amount of the piston 6 is reduced. Further, when the volume of the fluid chamber 9a is reduced, the differential pressure between the fluid chamber 9a and the fluid pressure chamber 9 during braking increases, and it takes until the pressures of the fluid chamber 9a and the fluid pressure chamber 9 become equal when braking is released. it takes longer. As a result, the duration of the sliding frictional force applied to the piston 6 by the piston seal 7 is lengthened, and the rollback amount of the piston 6 is increased.

As described above, the present invention changes the angle and length of the conical surface 6a formed on the outer wall of the piston 6, which is easy to process, without changing the shape of the piston seal mounting groove 3g or the piston seal 7. , the rollback amount of the piston 6 can be adjusted, so that the rollback amount of the piston 6 can be adjusted easily and accurately while reducing the cost. Further, since the piston seal 7 is in sliding contact with the outer peripheral surface of the piston 6 from when the friction pad 5 is brand new to when it reaches the specified full wear state, the sealing performance is not impaired. Furthermore, since the volume of the liquid chamber 9a is increased between the bottom side of the piston 6 and the cylinder hole 3d, even if the piston 6 tilts, the bottom side of the piston 6 and the cylinder hole 3d will contact each other. Abutment noise (judder) generated by contact can be suppressed.

FIGS. 4 to 13 show other embodiments of the present invention, and components showing the same components as in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. .

4 to 6 show a second embodiment of the present invention. In the piston 11 of this embodiment, a portion of the outer peripheral wall of the non-sealing area S2 is formed with a concave arcuate surface 11a. As a result, a fluid chamber 9a continuous with the fluid pressure chamber 9 is formed between the arc surface 11a and the cylinder hole 3d. can be adjusted with high precision.

7 to 9 show a third embodiment of the present invention. The piston 12 of this embodiment has four notches 12a in the cylinder axial direction on the outer peripheral wall of the non-sealing area S2. Hydraulic chambers 9a which are formed at equal intervals in the direction and which are continuous with the hydraulic pressure chambers 9 are defined between the cutouts 12a and the cylinder holes 3d. Therefore, the rollback amount of the piston 12 can be adjusted with high accuracy.

FIG. 10 shows a fourth embodiment of the present invention. In the cylinder hole 13 of this embodiment, the inner peripheral wall corresponding to the non-sealing area S2 of the piston 14 gradually increases toward the cylinder hole bottom side. It is formed with a conical surface 13a having a diameter. Further, the piston 14 is formed in a bottomed cylindrical shape with the same outer diameter from the opening to the bottom.

As a result, a fluid chamber 9a continuous with the fluid pressure chamber 9 is formed between the conical surface 13a and the outer peripheral wall of the piston 14. By changing the angle and length of the conical surface 13a, the roll of the piston 14 can be adjusted. The back amount can be adjusted with high accuracy. Furthermore, since the volume of the liquid chamber 9a is increased between the bottom side of the piston 14 and the cylinder hole 3d, even if the piston 14 tilts, the bottom side of the piston 14 and the cylinder hole 3d will contact each other. Abutment noise (judder) generated by contact can be suppressed.

FIG. 11 shows a fifth embodiment of the present invention. The cylinder hole 15 of this embodiment has a recessed arcuate surface 15a formed on the inner peripheral wall corresponding to the non-sealing area S2 of the piston 14. As shown in FIG. As a result, a fluid chamber 9a continuous with the fluid pressure chamber 9 is defined between the arc surface 15a and the outer peripheral wall of the piston 14, and the roll of the piston 14 can be changed by changing the depth and length of the arc surface 15a. The back amount can be adjusted with high accuracy.

12 and 13 show a sixth embodiment of the present invention. The cylinder hole 16 of this embodiment has six cuts in the cylinder axial direction on the inner peripheral wall corresponding to the non-sealing area S2 of the piston 14. Notch portions 16a are formed at regular intervals in the circumferential direction. As a result, fluid chambers 9a that are continuous with the fluid pressure chambers 9 are defined between the notches 16a and the outer peripheral wall of the piston 14. By changing the size and number of the notches 16a, the piston 14 can be adjusted with high accuracy.

In the first, fourth, and fifth embodiments, the liquid chamber is defined in the entire non-sealing region of the piston. may be located on the bottom side of the cylinder hole, and the liquid chamber may be defined in a part of the non-sealed area of the piston. In addition, in the second embodiment, the liquid chamber is defined in a part of the non-sealing area of the piston. A chamber may be defined. Furthermore, in the third embodiment and the sixth embodiment, the notch is formed in the axial direction of the cylinder, but the shape of the notch is not limited to this, and any shape may be used. The locations and the number of the grooves to be formed are arbitrary as long as they correspond to the non-sealing area S2 of the piston.

Further, the present invention is not limited to the pin-slide type disc brake as in the above embodiments, but can also be applied to a piston-facing type disc brake, and the number of pistons is arbitrary.

DESCRIPTION OF SYMBOLS 1... Vehicle disc brake, 2... Disc rotor, 3... Caliper body, 3a... Action part, 3b... Reaction part, 3c... Bridge part, 3d... Cylinder hole, 3e... Reaction claw, 3f... Dust seal mounting groove, 3g Piston seal mounting groove 3h Union hole 4 Caliper bracket 5 Friction pad 5a Lining 5b Back plate 6 Piston 6a Conical surface 7 Piston seal 8 Dust seal 9 Hydraulic pressure chamber 9a Liquid chamber 11 Piston 11a Arc surface 12 Piston 12a Notch 13 Cylinder hole 13a Conical surface 14 Piston 15 Cylinder hole 15a Arc Surface 16... Cylinder hole 16a... Notch

Claims (1)

A seal groove for fitting a piston seal is formed in a cylinder hole provided in the caliper body. A vehicle disc brake in which a fluid pressure chamber is defined between the piston and the cylinder hole by inserting toward the side,
The piston is
From the new state of the friction pad to the specified full wear state, the seal area on the piston opening side that contacts the piston seal, and the friction pad from the new state to the specified full wear state, and a non-sealing area on the bottom side of the piston that does not contact the piston seal,
A concave arcuate surface whose diameter gradually decreases toward the bottom of the piston is formed along a part of the outer peripheral wall of the non-sealing area over the entire circumference,
A disk brake for a vehicle, wherein a fluid chamber is defined between the outer peripheral wall of the non-sealed area of the piston and the cylinder hole, the fluid chamber continuing to the fluid pressure chamber.

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