JP2005344821A - Vehicular disc brake - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide braking stability comparable to a multi-pot type disc brake by an inexpensive single pot type disc brake, by stabilizing bearing pressure of a pad in braking by expanding a pad pressing area by a brake piston without extending a dimension in the disc axis direction of a caliper without causing an extreme cost increase and reduction in productivity. <P>SOLUTION: The pad pressing area by the brake piston 5 is expanded by forming a collar part 5a in the size corresponding to the substantially whole area of a friction surface of the pad 7 by expanding the collar part 5a on the tip of the brake piston 5 for pressing the pad 7. The brake piston 5 is preferably formed by combining the collar part 5a and a cylindrical part 5b by separative processing. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a disk brake for a vehicle that stabilizes the surface pressure of a friction pad during braking without causing problems such as cost increase and weight increase.

  Vehicle disc brakes are required to stabilize the friction pad surface pressure (pressure against the disc rotor) in order to improve braking stability. When the surface pressure of the friction pad (hereinafter simply referred to as a pad) is stabilized, uneven wear of the pad is suppressed, and a more preferable result is obtained.

By the way, in order to stabilize the surface pressure of the pad, it is necessary to make the pressure of the pad uniform over a wide range as much as possible (ideally, the uniform pressure is made at a position corresponding to the entire area of the friction surface. In order to achieve this, the following proposals have been proposed.
(1) The brake is made into a multi-pot type and one pad is pressed by a plurality of brake pistons.
(2) Using a brake piston having an oval cross section, the pad pressing area is expanded in the disk tangential direction.
(3) Increase the thickness of the pad back plate to increase the rigidity of the back plate.
(4) A pad pressing plate that increases the pressing area is interposed between the pad and the brake piston (see Patent Document 1 below).

  However, in the plan (1), the structure of the brake is complicated, the productivity is lowered, and there is a problem of cost increase due to an increase in the number of parts, an increase in the number of processing steps, and an increase in the number of assembly steps.

  Further, since the plan (2) uses a brake piston having an elliptical cross section or an elliptical cross section, the processing cost of the piston or cylinder is high, and it is difficult to reliably seal the outer periphery of the piston.

In addition, the proposals (3) and (4) respond to the demand for weight reduction by increasing the thickness of the pad back plate and adding the pad pressing plate to increase the caliper disk axial dimension and increase the weight of the brake device. I can't.
Japanese Utility Model Publication 4-75240

  The present invention does not cause an extreme increase in cost and productivity, and also stabilizes the surface pressure by expanding the pad pressing area by the brake piston without extending the disk axial dimension of the caliper. Even when a disc brake is adopted, it is an object to be able to obtain the same braking stability as a multi-pot type disc brake.

  In order to solve the above problems, in the present invention, in a vehicle disc brake in which at least one of a pair of friction pads is pressed by a brake piston and slidably contacted with a disc rotor, a flange provided at the tip of the brake piston The size of the flange portion is made to correspond to almost the entire area of the friction surface of the friction pad.

  The brake piston may be either a combination of the flange portion and the cylindrical portion that are separated and combined, or a shape in which the flange portion and the cylindrical portion are integrally formed, but the former brake piston is superior in productivity and cost. .

  The collar portion is preferably made of a punched material or a resin molded product at low cost.

  In addition, the brake piston that combines the flange and the cylindrical part by separating them is provided with a protrusion on the flange opposite to the friction pad pressing side of the flange, and the protrusion on the inner surface of the cylinder. A structure to be fitted is preferable.

  In addition, a stepped portion that separates a part of the surface from the pad back plate can be formed on the surface of the flange portion on the friction pad pressing side.

  The brake to which the present invention is applied may be a single pot type disc brake or a multipot type disc brake. Further, the present invention can be applied to both the floating type disc brake and the opposed piston type disc brake.

  In this invention, the flange portion at the tip of the brake piston has been expanded to a position where the dimension of the flange portion is substantially equal to the dimension of the pad lining, so that the pad pressing area by the brake piston corresponds to the entire friction surface. It is possible to stabilize the surface pressure of the pad by extending the width of the brake, and it is possible to improve the effectiveness of the brake and suppress uneven wear of the pad.

  In addition, the brake piston has been enlarged to expand the pad pressing area, which complicates the brake, increases the number of parts, deteriorates processability, increases costs, deteriorates the sealing performance of the piston periphery, and caliper discs. The problem of weight increase due to an increase in axial dimension does not occur.

  Note that a brake piston in which the flange portion and the cylindrical portion are separated and combined can be manufactured at low cost by forming the flange portion with a punching material or using a resin molded product.

  Moreover, what provided the protrusion in the collar part of the brake piston and made it fit in the inner surface of a cylindrical part can position a collar part and a cylindrical part using the said protrusion.

  Further, in the case where a step portion is formed on the pad pressing side surface of the collar portion, the surface pressure distribution of the pad can be changed by changing the size and position of the step portion, and the surface pressure distribution can be controlled. . Further, it is possible to make the surface pressure distribution of the inner side pad and the outer side pad the same by making the pressing area and the pressing area by the pressing means of the pair of pads substantially equal using the stepped portion.

  Embodiments of a disc brake according to the present invention will be described below with reference to the accompanying drawings. 1 to 4 show application examples to a floating disc brake. The floating disc brake is provided with slide guide portions 3 and 3 in the disc axial direction between the caliper 1 and the torque member 2 to support the caliper 1 so as to be slidable in the disc axial direction.

  A brake piston 5 is inserted into the cylinder 4 provided on the inner side of the caliper 1, and a pair of pads (friction pads) 7 and 8 are disposed on both sides of the disk (disk rotor) 6.

  In the disc brake, when braking by the driver is performed, hydraulic pressure is introduced into the cylinder 4, and the brake piston 5 receives the hydraulic pressure and is pushed out of the cylinder 4 to press the pad 7 on the inner side. Further, the caliper 1 slides to the inner side by the reaction force when the pad 7 is pressed against the disk 6, the outer pawl 9 of the caliper presses the pad 8 on the outer side, and the pad 8 is also pressed against the disk 6 for braking. Is made.

  The pad 7 has a disk tangential dimension larger than the diameter D of the brake piston 5. In the non-pressing region of the pad 7 (the portion outside the outer diameter of the brake piston 5), the surface pressure decreases as the separation distance from the brake piston 5 increases because the pad bends during braking.

  In order to suppress the reduction of the surface pressure, in the present invention, the flange portion 5a at the tip of the brake piston 5 is enlarged as shown in FIG. 4 (conventionally, the flange portion 5a has the same diameter as the cylindrical portion 5b). The flange portion 5a has a size (substantially the same as the contour of the lining 7a) corresponding to almost the entire friction surface of the pad. Thereby, the pressing area of the pad 7 by the brake piston 5 can be expanded to an ideal level without increasing the length L of the brake piston 5.

  The brake piston 5 may be either one in which the flange portion 5a and the cylindrical portion 5b are separated or one in which the flange portion 5a and the cylindrical portion 5b are integrally formed. The former piston that separates the flange portion 5a and the cylindrical portion 5b can form the flange portion 5a with a punched material (press-processed product) excellent in workability capable of reducing the cost. The boot mounting groove 5e provided between the flange 5a and the flange portion 5a can be easily processed.

  Further, as shown in FIG. 5, the separated flange portion 5a and cylindrical portion 5b are provided with a protrusion 5c protruding on the surface opposite to the friction pad pressing side on the flange portion 5a, and the protrusion 5c is formed into the cylindrical portion 5b. When they are fitted to the inner surface of the two, they can be positioned easily. The protrusion 5c may be formed by bending a part of the material.

  The flange portion 5a may be a resin molded product. The resin flange 5a is excellent in heat insulation. In this invention, an enlarged flange 5a is interposed between the pad back plate 7b and the piston boot 10, and the flange 5a serves as a heat shielding material to protect the piston boot 10 from braking heat. The protective effect can be further enhanced by using the resin flange 5a.

  As shown in FIG. 6, a step portion 5 d that separates a part of the surface from the pad back plate 7 b can be formed on the surface of the flange portion 5 a on the friction pad pressing side. When the position and size of the stepped portion 5d are changed, the surface pressure distribution of the pad 7 changes, and therefore, the one having the stepped portion 5d can control the surface pressure distribution.

  The caliper floating type disc brake is known that the caliper 1 swings during braking, so that the surface pressure on the inner side of the pad is higher than the surface pressure on the outer side of the disc. The pressing center of the pad 7 by the brake piston 5 may be offset (biased) toward the disk delivery side. The thing which has the level difference part 5d can give the offset of the press center using the level difference part 5d.

  In addition, the caliper floating type disc brake has an asymmetrical shape in which the pressing area of the pad 8 by the caliper outer claws 9 (see FIG. 7) and the pressing area of the pad 7 by the brake piston 5 are usually asymmetrical. If 5d is provided, it becomes possible to make the pressing area of the pad 7 by the brake piston 5 and the pressing area of the pad 8 by the outer claw 9 symmetrical, so that the pressing area and the pressing area of the pads 7, 8 are almost equal.

  Furthermore, it is possible to adjust the position and size of the stepped portion 5d to create a pressing state that approximates pad pressing (see FIG. 8) by a plurality of pistons employed in a multi-pot type disc brake.

  As described above, in the disc brake of the present invention, since the flange portion of the brake piston is enlarged, the pad pressing area by the brake piston is expanded without increasing the size of the caliper in the disc axial direction, thereby stabilizing the surface pressure of the pad. Therefore, it is possible to obtain braking stability equivalent to a multi-pot type disc brake with an inexpensive single-pot type disc brake. Further, stabilization of the surface pressure suppresses uneven wear of the pad, and a better result is obtained with regard to higher performance.

Plan view showing an example of a disc brake of the present invention Sectional view along the line II-II in FIG. Sectional view along line III-III in FIG. The perspective view which shows an example of the brake piston employ | adopted by this invention (A) Sectional view of the brake piston of FIG. 4, (b) Front view of the piston The figure which shows the example which provided the level | step-difference part for surface pressure adjustment in the collar part of the piston front-end | tip The figure which shows the pad press area by the outer nail | claw of a caliper The figure which shows the pad press area by two or more pistons

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Caliper 2 Torque member 3 Slide guide part 4 Cylinder 5 Brake piston 5a Gutter part 5b Cylindrical part 5c Projection 5d Step part 5e Boot installation groove 6 Disc 7, 8 Pad 7a Lining 7b Back plate 9 Outer claw 10 Piston boot

Claims (7)

  In a vehicle disc brake in which at least one of a pair of friction pads is pressed by a brake piston and slidably contacted with a disc rotor, a flange provided at the tip of the brake piston is enlarged, and the flange is made a friction surface of the friction pad. A disc brake for a vehicle characterized by having a size corresponding to almost the entire area.   The disc brake for a vehicle according to claim 1, wherein the flange portion and the cylindrical portion of the brake piston are separated and combined.   The vehicle disc brake according to claim 2, wherein the flange portion is formed of a punching material.   A protrusion is provided on the flange portion that protrudes on the surface opposite to the friction pad pressing side of the flange portion, and the protrusion is fitted to the inner surface of the cylindrical portion of the brake piston to connect the flange portion and the cylindrical portion. 4. The vehicle disc brake according to claim 2, wherein the vehicle disc brakes are positioned with respect to each other.   The vehicle disc brake according to claim 1, wherein at least the flange portion is made of resin.   The vehicular disc brake according to any one of claims 1 to 5, wherein a step portion for separating a part of the surface from the pad back plate is formed on a surface of the flange portion on the friction pad pressing side.   7. The vehicle disc brake according to claim 6, wherein a pressing area and a pressing area by the pressing means of the pair of friction pads are substantially equal.

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