JP2012207733A - Disc brake - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disc brake for restraining a brake squeak, capable of simplifying a structure, and capable of improving manufacturing efficiency.SOLUTION: The center Om of the inner periphery of a seal groove 26 for arranging a piston seal 27, is deviatively arranged on the disc turn-in side more than the center Ob of the inner periphery of a bore 20, and in a state of not introducing hydraulic pressure into the bore 20, an outer peripheral surface 28 of a piston 18 abuts on an inner peripheral surface 25a of a bore 19 on the brake pad 13 side more than the seal groove 26, and is arranged to have a clearance on an inner peripheral surface 25b of the bore 19 on the bottom part 21 side more than the seal groove 26.

Description

  The present invention relates to a disc brake.

  It is known that the brake pad has a higher degree of wear on the inlet side than on the outlet side in the disk rotation direction during forward running. Therefore, the uneven wear generated in the brake pad is worn more on the inlet side than on the outlet side. If the brake pad is partially worn as described above during light pressure braking when the driver steps lightly on the brake pedal to adjust the vehicle speed, etc., only a part of the exit side where the brake pad wear has not progressed is disc Will come into contact. Then, the behavior of the brake pad may become unstable, and the brake squeal may occur.

  For this reason, there is a technique in which a spring is provided between the piston and the bore of the caliper to incline the piston and the caliper in accordance with the partial wear of the pad at the time of slight pressure braking (see, for example, Patent Document 1).

JP 2010-175040 A

  However, if the spring is provided as described above, the structure becomes complicated and the production efficiency is lowered.

  An object of the present invention is to provide a disc brake capable of suppressing brake squeal, simplifying the structure, and improving manufacturing efficiency.

  In order to achieve the above object, according to the present invention, the center of the inner periphery of the seal groove in which the piston seal is arranged is provided so as to be shifted from the center of the inner periphery of the bore toward the disk entry side. In a state where no hydraulic pressure is introduced, the outer peripheral surface of the piston abuts on the inner peripheral surface of the bore on the brake pad side with respect to the seal groove, and the clearance on the inner peripheral surface of the bore on the bottom side with respect to the seal groove Arranged.

  ADVANTAGE OF THE INVENTION According to this invention, while suppressing a brake squeal, a structure can be simplified and manufacturing efficiency can be improved.

It is a sectional side view showing the disc brake concerning a 1st embodiment of the present invention. FIG. 2 is a cross-sectional view corresponding to AA in FIG. 1 showing the concept of exaggerating the clearance and seal between the piston and bore of the disc brake according to the first embodiment of the present invention. It is sectional drawing which shows the concept of the disc brake which concerns on 1st Embodiment of this invention, Comprising: (a) is before braking, (b) is a fine pressure braking first term, (c) is a slight pressure braking late term. . It is sectional drawing which shows the concept of the disc brake which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows the concept of the disc brake which concerns on 3rd Embodiment of this invention.

“First Embodiment”
A disc brake according to a first embodiment of the present invention will be described below with reference to FIGS.

  The disc brake 10 of the first embodiment shown in FIG. 1 is for a vehicle such as an automobile, and brakes the vehicle by braking a disc 11 that rotates together with a wheel (not shown). The disc brake 10 is slidable in a carrier 12, a pair of brake pads 13 and 14 supported so as to be slidable in the axial direction of the disc 11, and the carrier 12 in the axial direction of the disc 11. And a caliper 15 that is supported by.

  The carrier 12 is disposed so as to straddle the disk 11 in the axial direction, and is fixed to a non-rotating portion of the vehicle. The pair of brake pads 13 and 14 are supported by the carrier 12 on both sides in the rotational direction of the disk 11 in a state of being opposed to both surfaces of the disk 11, and slide in the axial direction of the disk 11 in this supported state. It becomes possible.

  The caliper 15 includes a caliper body 17 supported by the carrier 12 so as to be slidable in the axial direction of the disk 11 while straddling the outer diameter side of the disk 11, and a surface on one side of the disk 11 on the caliper body 17. And a piston 18 arranged so as to oppose to each other. A bottomed bore 19 is formed in the caliper body 17 along the axial direction of the disk 11, and a piston 18 is movably fitted in the bore 19. Here, the piston 18 has a bottomed cylindrical shape, and is fitted to the bore 19 so that the bottom 20 faces the bottom 21 of the bore 19. Further, the caliper body 17 is formed with a claw portion 22 disposed so as to face the other surface of the disk 11.

  The caliper 15 moves the piston 18 to the claw portion 22 side along the axial direction of the disk 11 by the hydraulic pressure introduced into the bore 19 from the flow hole 24 of the bottom portion 21. The pair of brake pads 13 and 14 are pressed against the disk 11 with the claw portion 22 to apply frictional resistance to the disk 11 for braking. The disc brake 10 is arranged in the vehicle with the piston 18 on the inner side in the vehicle width direction and the claw portion 22 on the outer side in the vehicle width direction. Thereby, the brake pad 13 on the piston 18 side becomes an inner pad arranged on the inner side in the vehicle width direction, and the brake pad 14 on the claw portion 22 side becomes an outer pad arranged on the outer side in the vehicle width direction.

  An annular seal groove 26 having a larger diameter than the inner peripheral surface 25 is formed on the inner peripheral surface 25 of the bore 19 at a position separated from the bottom portion 21. An annular piston seal 27 is formed in the seal groove 26. Is arranged. The piston seal 27 is fitted to the inner periphery of the piston seal 27 so that the piston 18 is in close contact with the inner periphery of the piston seal 27, thereby sealing the outer peripheral surface 28 of the piston 18. The piston seal 27, the bore 19, and the piston 18 form a hydraulic fluid chamber 29 that communicates with the flow hole 24 in the caliper 15. The brake pad 13 is composed of a friction material 13A and a back plate 13B that supports the friction material 13A, and the brake pad 14 is also composed of a friction material 14A and a back plate 14B that supports the friction material 14A. The friction material 13A, 14A contacts the disk 11 on the lining surfaces 13a, 14a opposite to the back plates 14A, 14B.

2, the inner peripheral surface 25 of the bore 19 has a small-diameter inner peripheral surface 25a on the brake pad 13 side with respect to the seal groove 26, and a bottom portion 21 side with respect to the seal groove 26 is concentric with the small-diameter inner peripheral surface 25a. The large-diameter inner peripheral surface 25b is larger than the small-diameter inner peripheral surface 25a. Therefore, the piston clearance Cp on the small diameter inner peripheral surface 25a side = the inner diameter Dcp of the small diameter inner peripheral surface 25a−the piston outer diameter Dp, and the piston clearance Cs on the large diameter inner peripheral surface 25b side = the inner diameter Dcs− on the large diameter inner peripheral surface 25b. When the piston outer diameter is Dp, the following expression (1) is satisfied.
Cs> Cp (1) formula

  The center line Om of the inner peripheral surface (groove bottom surface) of the seal groove 26 is closer to the inlet side in the rotational direction R of the disk 11 during forward travel of the vehicle than the center line Ob of the small-diameter inner peripheral surface 25a of the bore 19 (hereinafter referred to as (Referred to as the disk feed-in side) with an eccentricity δ shifted. The piston seal 27 has a constant radial width over the entire circumference, and the outer periphery of the piston seal 27 abuts against the inner circumferential surface of the seal groove 26 over the entire circumference. Therefore, the piston seal 27 is also fitted in the seal groove 26 and the piston 18 is not fitted, so that the center line of the inner periphery thereof coincides with the center line Om of the seal groove 26, and the inner periphery of the bore 19. The center line Ob is shifted from the center line Ob toward the disk insertion side.

Here, the amount of eccentricity δ between the center line Om of the seal groove 26 and the center line Ob of the inner peripheral surface 25 of the bore 19 is relative to the piston clearance Cp between the small-diameter inner peripheral surface 25a of the bore 19 and the outer peripheral surface of the piston 18. It is set so as to satisfy the following expression (2).
δ> Cp / 2 (2) equation

  Due to the condition of the expression (2), the outer peripheral surface 28 of the piston 18 is within the small diameter of the bore 19 on the brake pad 13 side of the seal groove 26 with no hydraulic pressure being introduced into the bore 19 as shown in FIG. It abuts on the circumferential surface 25a on the disk insertion side. In addition, the outer peripheral surface 28 of the piston 18 is larger than the seal groove 26 on the bottom portion 21 side with the large diameter inner peripheral surface of the bore 19 in a state in which no fluid pressure is introduced into the bore 19 due to the condition of the above-described equation (1). 25b is arranged with a clearance over the entire circumference.

  As described above, the frictional force Fout on the disk delivery side is larger than the frictional force Fin on the disk delivery side as the friction force on the piston 18 by the piston seal 27. Note that, as the eccentricity δ is larger than the value of Cp / 2 (in other words, the value of δ−Cp / 2 is larger) according to the condition of the expression (2), the disk delivery side is more Since the seal tightening margin between the pistons 18 is increased, the difference between the frictional force Fout and the frictional force Fin is also increased.

  Due to the difference in frictional force, the stroke of the piston 18 is caused by the stroke of the piston 18 during fine pressure braking when the hydraulic pressure introduced into the bore 19 from the master cylinder (not shown) by the operation of the brake pedal is low and the influence of the frictional force by the piston seal 27 is large. The stroke on the feed-in side is larger than the stroke on the disc feed-out side because of less frictional resistance.

  Specifically, as shown in FIG. 3A, the friction members 13A and 14A of the pair of brake pads 13 and 14 are in a partial wear state in which the disk inlet side is worn more than the disk outlet side. When the hydraulic pressure in the hydraulic fluid chamber 29 is increased by the slight pressure braking when the vehicle is moving forward, the piston 18 is placed on the disk entry side shown in FIG. An attempt is made to make the stroke Sin obliquely so that it is greater than the stroke Sout on the disk delivery side. On the other hand, the brake pad 13 on the piston 18 side is unevenly worn so that the friction material 13A allows this oblique stroke, so the piston 18 strokes obliquely. As a result, as shown in FIG. 3 (b), the brake pad 13 is pressed by the diagonal stroke of the piston 18 so that the disk insertion side with large wear is stroked greatly, and the disk delivery side with low wear is stroked small. As a result, the lining surface 13a of the friction material 13A is brought into full contact with the disk 11. At this time, in the bore 19, the tilt of the piston 18 is allowed by the clearance between the large-diameter inner peripheral surface 25 b and the outer peripheral surface 28 of the piston 18 according to the condition of the expression (1).

  Further, when the hydraulic pressure in the hydraulic fluid chamber 29 rises and the piston 18 strokes, the caliper 15 moves the claw portion 22 against the disk 11 with respect to the piston 18 whose axial movement with respect to the disk 11 is restricted via the brake pad 13. The claw portion 22 presses the brake pad 14 on the claw portion 22 side against the disk 11. At this time, since the large-diameter inner peripheral surface 25b of the bore 19 allows the piston 18 to be tilted by the clearance with the piston 18 under the condition of the expression (1), as shown in FIG. The entire caliper 15 including the tilting of the caliper 15 in the θ direction so that the disc insertion side where the wear of the brake pad 14 is large makes a large stroke and the disc supply side where the wear is small makes a small stroke in accordance with the uneven wear of the brake pad 14. . As a result, the lining surface 14a of the friction material 14A is brought into full contact with the disk 11.

  As described above, the lining surfaces 13a and 14a of the friction members 13A and 14A of the pair of brake pads 13 and 14 are immediately after the start of the fine pressure braking such as speed adjustment in the state where the brake pads 13 and 14 are partially worn and during the fine pressure braking. The entire surface can be brought into contact with the disk 11. Thereby, the brake squeal at the time of the low pressure braking of the disc brake 10 can be suppressed. Moreover, the center line Om of the inner periphery of the seal groove 26 is shifted from the center line Ob of the inner periphery of the bore 20 toward the disk insertion side, and the outer peripheral surface 28 of the piston 18 is set to the brake pad 13 rather than the seal groove 26. The structure can be simplified and the manufacturing efficiency can be improved because the inner peripheral surface 25b of the bore 19 closer to the bottom 21 than the seal groove 26 should be provided with a clearance on the inner peripheral surface 25b of the bore 19 on the bottom portion 21 side. Can be improved.

In addition, the amount of uneven wear of the brake pads 13 and 14 is large, and the inclination angle of the piston 18 necessary for bringing the lining surfaces 13a and 14a of the friction materials 13A and 14A of the brake pads 13 and 14 into full contact with the disk 11 ( Even if the lining surfaces 13a and 14a remain in partial surface contact with the disk 11, compared with the one-point contact when the piston 18 is not tilted, the pressure applied during the slight pressure braking is not obtained. The effect of suppressing brake noise is obtained. That is, the eccentric amount δ may be set as follows.
δ = Cp / 2 + α (α is a value sufficiently smaller than the dimensional tolerance such as seal tightening allowance)

  Here, during normal braking where the hydraulic pressure introduced into the hydraulic fluid chamber 29 is high, the hydraulic pressure applied to the piston 18 is sufficiently larger than the influence of the frictional force due to the piston seal 27, so the brake pads 13, 14. The lining surfaces 13a and 14a of the friction members 13A and 14A of the brake pads 13 and 14 are entirely applied to the disk 11 regardless of whether the wear is unevenly worn or not. Will be in contact.

“Second Embodiment”
Next, the disc brake according to the second embodiment will be described mainly on the difference from the first embodiment based on FIG. In addition, about the site | part which is common in 1st Embodiment, it represents with the same name and the same code | symbol.

In the first embodiment, in order to form a clearance allowing the tilting of the piston 18 between the bore 19 and the bore 19, the bore 19 has a larger diameter than the small-diameter inner peripheral surface 25 a on the side opposite to the bottom 21. The large-diameter inner peripheral surface 25b is provided. On the other hand, in the second embodiment, the inner peripheral surface 25 of the bore 19 has a constant diameter concentric before and after the seal groove 26 (that is, Dcp = Dcs = Dc), and the outer peripheral surface 28 of the piston 18 is formed on the bottom 20 side. A small-diameter outer peripheral surface 28a and a large-diameter outer peripheral surface 28b having a larger diameter than the small-diameter outer peripheral surface 28a on the side opposite to the bottom portion 20 are configured. That is, the outer diameter Dps of the small-diameter outer peripheral surface 28a and the outer diameter Dpp of the large-diameter outer peripheral surface 28b are set so as to satisfy the following expression (1) ′.
Dpp> Dps (1) 'formula

If Cp ′ = Dc−Dpp, the eccentricity δ is set so as to satisfy the following expression (2) ′.
δ> Cp ′ / 2 (2) ′ formula

“Third Embodiment”
Next, the disc brake according to the third embodiment will be described mainly based on FIG. 5 with a focus on the differences from the second embodiment. In addition, about the site | part which is common in 2nd Embodiment, it represents with the same name and the same code | symbol.

In the third embodiment, as in the second embodiment, the inner peripheral surface 25 of the bore 19 has a concentric constant diameter before and after the seal groove 26 (that is, Dcp = Dcs = Dc), but is different from the second embodiment. The outer peripheral surface 28 of the piston 18 is composed of a large-diameter outer peripheral surface 28b opposite to the bottom portion 20 and a tapered surface 28c on the bottom portion 20 side having a smaller diameter as the distance from the large-diameter outer peripheral surface 28b increases. Here, the minimum outer diameter of the tapered surface 28c is the outer diameter Dps, and is set so as to satisfy the expressions (1) ′ and (2) ′ as in the second embodiment.
In each of the above embodiments, the example in which the seal groove is eccentric with respect to the bore has been described. The inner peripheral surface of the seal may be decentered by changing the thickness in the direction. However, in this case, it is necessary to stop the seal.
Moreover, although the said embodiment showed the example of the pin slide type disc brake, it is also possible to apply to an opposing type disc brake.

DESCRIPTION OF SYMBOLS 10 Disc brake 11 Disc 12 Carrier 13, 14 Brake pad 15 Caliper 18 Piston 19 Bore 21 Bottom part 25 Inner peripheral surface 26 Seal groove 27 Piston seal 28 Outer peripheral surface Ob Center of inner periphery of bore Om Center of inner periphery of seal groove

Claims (2)

A brake pad disposed opposite to the disk, a piston that presses the brake pad, and a caliper formed with a bottomed bore that is disposed so that the piston is moved by the introduced hydraulic pressure. In the disc brake in which an annular seal groove in which a piston seal for sealing the outer periphery of the piston is disposed is formed on the inner peripheral surface of the bore,
The center of the inner periphery of the piston seal is provided in a state where there is no piston and is shifted from the center of the inner periphery of the bore toward the disk entry side, and no fluid pressure is introduced into the bore. The outer peripheral surface of the piston abuts on the inner peripheral surface of the bore closer to the brake pad than the seal groove, and is disposed with a clearance on the inner peripheral surface of the bore closer to the bottom than the seal groove. Disc brake characterized by.   The disc brake according to claim 1, wherein an inner peripheral center of the seal groove is shifted from a center of the inner periphery of the bore toward the disc insertion side.

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