JP4847924B2 - Vehicle disc brake - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a disk brake for a vehicle, which is of a simple structure and whereby the entry of dirt into a cylinder hole is positively prevented and the roll back of a piston after releasing a braking force is not affected. <P>SOLUTION: A dust seal 8 is fitted to the dust seal fitting groove 3e of the cylinder hole 3c formed in a caliper body 3, and brought into slidable contact with the outer peripheral surface 5a of the piston 5 to prevent the dirt from entering into the cylinder hole 3c. An annular base part 8b contained in the dust seal fitting groove 3e and having a gap E formed between the inner peripheral surface 8a thereof and the outer peripheral surface 5a of the piston 5 and a lip part 8d projecting from the annular base part 8b to the cylinder hole opening side and having the inner peripheral surface 8c brought into slidable contact with the outer peripheral surface 5a of the piston 5 are integrally formed of a resin material. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a vehicle disc brake provided with a dust seal that is disposed on a cylinder hole opening side of a caliper body and prevents dust from entering the cylinder hole.

A disc brake for a vehicle has a piston slidably inserted in a cylinder hole opened on the disc rotor side, and the piston inner surface is slidably in contact with the outer peripheral surface of the piston so that the piston is liquid-tight and movable. A piston seal that has a function of automatically holding the gap between the friction pad and the disk rotor by rolling back the piston after releasing the braking force by a predetermined amount, and sliding into the outer peripheral surface of the piston into the cylinder hole And a dust seal for preventing intrusion of dust (see, for example, Patent Document 1).
JP 2000-283190 A

  However, in the above-mentioned, since the entire inner surface of the dust seal is in sliding contact with the outer peripheral surface of the piston, when the piston seal rolls back the piston by a predetermined amount after the braking force is released, the tight force of the dust seal causes the piston to roll back. There was a risk of damage.

  Accordingly, the present invention provides a vehicular disc brake that has a simple structure and reliably prevents dust from entering the cylinder bore and does not affect the rollback of the piston after the braking force is released. It is aimed.

In order to achieve the above object, the present invention provides a piston seal which is fitted into a dust seal fitting groove formed on an inner peripheral surface of a cylinder hole provided in a caliper body, and is inserted into the cylinder hole via a piston seal. In a vehicle disc brake having a dust seal that is in sliding contact with an outer peripheral surface and prevents dust from entering the cylinder hole, the dust seal includes an annular base portion having a quadrangular cross section that is received in the dust seal fitting groove, is offset to the piston side of the annular base portion, integrally includes a lip portion projecting from the inner periphery of the cylinder hole opening side of the dust seal fitting groove, the inner peripheral surface of said annular base, said piston and formed in a non-contact surface which does not contact with the outer peripheral surface, allowed to exist a gap between the inner peripheral surface and the outer peripheral surface of said piston of said annular base, the inner peripheral surface of the lip portion Characterized in that formed as sliding contact with the outer peripheral surface of the piston, the lip, it is preferable that progressively is formed thinner toward the tip side. The dust seal fitting groove has an annular recess formed to open at the opening end of the cylinder hole, and an L-shaped cross section fitted to the annular recess covering the cylinder hole opening end side of the annular recess. It is also possible to form with an annular retainer. Further, the friction coefficient of the surface of the lip portion that is in sliding contact with the outer peripheral surface of the piston may be set lower than the friction coefficient of the piston seal that is in sliding contact with the outer peripheral surface of the piston. The cylinder hole is formed such that the diameter of the opening side cylinder portion on the cylinder hole opening side of the dust seal mounting groove is larger than the diameter of the cylinder hole on the cylinder hole bottom side of the dust seal mounting groove, The clearance E formed between the inner peripheral surface of the annular base portion of the dust seal and the outer peripheral surface of the piston is narrower than the clearance X formed between the opening-side cylinder portion and the outer peripheral surface of the piston, and It is preferable that the gap Y is formed equal to or wider than the gap Y formed between the cylinder hole on the cylinder hole bottom side than the dust seal mounting groove and the outer peripheral surface of the piston.

  As described above, according to the present invention, the dust seal forms a gap between the inner peripheral surface of the annular base portion and the outer peripheral surface of the piston so as not to apply a pressing force to the annular base portion. Since the lip portion is formed at the position offset to the side, the rollback of the piston after releasing the braking force is not affected. In addition, the lip portion can reliably prevent dust from entering the cylinder hole.

  Furthermore, the dust attached to the piston tip side can be efficiently removed by forming the lip portion gradually thinner toward the tip side. Moreover, the dust seal fitting groove can be easily processed by forming the dust seal fitting groove with an annular recess and an annular retainer opened at the opening end of the cylinder hole. Furthermore, by setting the friction coefficient of the surface of the lip portion that is in sliding contact with the outer peripheral surface of the piston to be lower than that of the piston seal that is in sliding contact with the outer peripheral surface of the piston, the piston can be rolled back more reliably after the braking force is released. Can be made.

  Further, the gap E formed between the inner peripheral surface of the annular base portion of the dust seal and the outer peripheral surface of the piston is narrower than the gap X formed between the opening side cylinder portion and the outer peripheral surface of the piston, and The space where the lip portion of the dust seal acts is formed by being equal to or wider than the gap Y formed between the cylinder hole on the cylinder hole bottom side of the dust seal mounting groove and the outer peripheral surface of the piston. It can be ensured, and when the dust seal is assembled to the piston or when the piston slides, the dust seal can be reliably prevented from being pulled into the gap Y and damaged.

  Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show a first embodiment of the present invention, FIG. 1 is an enlarged cross-sectional view showing a dust seal fitting state, and FIG. 2 is a cross-sectional front view of a disc brake.

  The hydraulic disc brake 1 includes a disc rotor 2 that rotates integrally with a wheel (not shown), a caliper body 3 that is attached to a vehicle body at one side of the disc rotor 2, and a disc rotor 2 that is disposed inside the caliper body 3. It consists of a pair of friction pads 4 and 4 that are placed opposite to each other.

  The caliper body 3 includes a pair of action portions 3a and 3a disposed on both sides of the disc rotor 2, and a bridge portion 3b that connects the stride across the outer periphery of the disc rotor 2, and each action portion 3a includes a cylinder. Holes 3c and 3c are formed to face each other. In each cylinder hole 3c, a cup-shaped piston 5 is liquid-tightly accommodated. Each piston 5 moves in the cylinder hole 3c in the direction of the disk rotor by the hydraulic pressure supplied to the hydraulic chamber 6 defined between the piston 5 and the bottom of the cylinder hole 3c, and moves the friction pad 4 to the disk rotor. Pushing toward the side surface of the rotor 2, thereby applying a braking force to the disk rotor 2.

  On the inner peripheral surface of the cylinder hole 3c, an annular piston seal fitting groove 3d is provided in the middle in the axial direction, and an annular dust seal is fitted closer to the cylinder hole opening side than the piston seal fitting groove 3d. A groove 3e is provided around. The piston seal fitting groove 3d is fitted with a piston seal 7 which is in fluid-tight sliding contact with the outer peripheral surface 5a of the piston 5 and rolls back the piston 5 with its restoring force, and the dust seal fitting groove 3e is fitted with the piston seal fitting groove 3d. A dust seal 8 is slidably brought into contact with the outer peripheral surface 5a of the piston 5 and prevents dust from entering the cylinder hole 3c.

  The piston seal 7 is formed of an elastic material such as a rubber material having a quadrangular cross-section, and the piston seal 7 is released after the braking force is released by taking into account its hardness and compression force and the friction coefficient and shape of the inner peripheral surface 7a that is in sliding contact with the piston 5. 5 is formed so that a predetermined amount can be rolled back.

  The dust seal 8 is formed of an elastic material such as a rubber material equivalent to the piston seal 7, and integrally includes an annular base portion 8b and a lip portion 8d. The annular base portion 8b is accommodated in the dust seal fitting groove 3e, and a gap E is formed between the inner peripheral surface 8a of the annular base portion 8b and the outer peripheral surface 5a of the piston 5. The lip portion 8d protrudes from the annular base portion 8b toward the cylinder hole opening side, and protrudes from the inner peripheral surface of the cylinder hole opening side surface of the dust seal fitting groove 3e toward the cylinder hole opening portion side. The lip portion 8d is gradually thinned toward the front end side, the outer peripheral surface is formed in a conical shape, the inner peripheral surface 8c on the front end side is in sliding contact with the outer peripheral surface 5a of the piston 5, and the inner side on the front end side is also formed. The friction coefficient of the peripheral surface 8 c is set lower than the friction coefficient of the piston seal 7.

  In the disc brake 1 formed in this way, when the hydraulic fluid whose pressure has been increased is supplied to the hydraulic pressure chamber 6 of the caliper body 3 by the braking operation of the driver, each piston 5 moves forward in the cylinder hole 3c in the opening direction. The friction pad 4 is pressed against the disk rotor 2, and a braking force acts on the disk rotor 2. As the piston 5 advances during braking, the inner peripheral surface 7a of the piston seal 7 is dragged to the outer peripheral surface 5a of the piston 5, and the piston seal 7 is elastically deformed toward the cylinder hole opening side.

  When the pressure in the hydraulic chamber 6 decreases due to the release of the braking operation, the piston 5 rolls back by a predetermined amount by the restoring force that returns the piston seal 7 to its original shape. At this time, the dust seal 8 has a gap E formed between the inner peripheral surface 8a of the annular base portion 8b and the outer peripheral surface 5a of the piston 5, and the outer peripheral surface 5a of the piston 5 has a friction coefficient of the piston seal 7. However, since only the inner peripheral surface 8c on the front end side of the lip portion 8d having a low friction coefficient is in sliding contact, the piston 5 can be rolled back by a predetermined amount without being obstructed by the dust seal 8.

  Further, as the piston 5 moves backward, the tip end side of the lip portion 8d comes into sliding contact with the outer peripheral surface 5a of the piston 5, and dust adhering to the tip end side of the piston 5 is efficiently removed, and dust enters the cylinder hole 3c. Can be reliably prevented. Further, since the lip portion 8d is gradually thinned toward the tip end side, dust can be removed well.

  FIG. 3 is an enlarged cross-sectional view of the dust seal fitting state according to the second embodiment of the present invention, and FIG. 4 is an enlarged cross-sectional view of the dust seal fitting state according to the third embodiment of the present invention. The same components are denoted by the same reference numerals, and detailed description thereof is omitted.

  The dust seal fitting groove 3f of the second embodiment shown in FIG. 3 is fitted to cover the annular recess 3g formed at the opening end of the cylinder hole 3c and the cylinder hole opening end side of the annular recess 3g. And an annular retainer 3h having an L-shaped cross section. The dust seal 8 is fitted after the dust seal fitting groove 3f is formed, or is accommodated in the annular retainer 3h, and fitted into the annular recess 3g together with the annular retainer 3h, and the lip portion 8d is attached to the side surface of the annular retainer 3h that opens the cylinder hole. From the inner peripheral surface, the cylinder hole is projected to the opening side. Thus, by forming the dust seal fitting groove 3f, the dust seal fitting groove can be easily processed.

  The cylinder hole of the third embodiment shown in FIG. 4 has a diameter of the opening side cylinder portion 3j closer to the cylinder hole opening side than the dust seal mounting groove 3i and a diameter of the cylinder hole 3k closer to the cylinder hole bottom side than the dust seal mounting groove 3i. Further, the gap E formed between the inner peripheral surface 8a of the annular base portion 8b of the dust seal 8 and the outer peripheral surface 5a of the piston 5 is an outer peripheral surface of the opening-side cylinder portion 3i and the piston 5. It is narrower than the gap X formed between the cylinder hole 5a and the gap Y formed between the cylinder hole 3k and the outer peripheral surface 5a of the piston 5 or wider than the gap Y. As a result, a space in which the lip portion 8d of the dust seal 8 acts can be secured, and the dust seal 8 is pulled into the gap Y and is damaged when the dust seal 8 is assembled to the piston 5 or when the piston slides. Can be reliably prevented. Further, the gap X formed between the opening-side cylinder portion 3 i and the outer peripheral surface 5 a of the piston 5 may be dimensioned so as not to crush the proximal end side of the lip portion 8 d of the dust seal 8.

  As described above, the dust seal of the present invention is not limited to being formed of an elastic material such as a rubber material equivalent to the piston seal, but may be formed of a hard resin material having a low friction coefficient such as nylon. . In addition, as a method for setting the friction coefficient of the surface of the lip portion that is in sliding contact with the outer peripheral surface of the piston, for example, to reduce the tightening margin for the piston of the lip portion or to reduce the surface of the lip portion or the sliding surface of the piston. There are some which perform a treatment (coating) to obtain a friction coefficient, or use a material having a small friction coefficient. Not limited to this, a well-known method for reducing the friction coefficient can be applied. Furthermore, the present invention is not limited to those applied to piston-facing disc brakes, but can be applied to any type of disc brake.

It is an expanded sectional view which shows the fitting state of the dust seal | sticker which shows the 1st form example of this invention. It is a sectional front view of a disk brake similarly. It is an expanded sectional view which shows the fitting state of the dust seal | sticker which shows the 2nd form example of this invention. It is an expanded sectional view which shows the fitting state of the dust seal | sticker which shows the 3rd example of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Disc brake, 2 ... Disc rotor, 3 ... Caliper body, 3a ... Action part, 3b ... Bridge part, 3c ... Cylinder hole, 3d ... Piston seal fitting groove, 3e, 3f ... Dust seal fitting groove, 3g ... Ring Recessed part, 3h ... annular retainer, 3i ... dust seal fitting groove, 3j ... open side cylinder part, 3k ... cylinder hole, 4 ... friction pad, 5 ... piston, 5a ... outer peripheral surface, 6 ... hydraulic chamber, 7 ... piston seal 7a ... inner peripheral surface, 8 ... dust seal, 8a ... inner peripheral surface, 8b ... annular base, 8c ... inner peripheral surface, 8d ... lip portion, E, X, Y ... gap

Claims (5)

Fit in a dust seal fitting groove formed on the opening side inner peripheral surface of the cylinder hole provided in the caliper body, and slidably contact with the outer peripheral surface of the piston inserted through the piston seal into the cylinder hole. In a vehicle disc brake provided with a dust seal that prevents dust from entering the dust seal, the dust seal is offset to the piston side with respect to the annular base, and an annular base having a quadrangular cross-section received in the dust seal fitting groove. are, integrally includes a lip portion projecting from the inner periphery of the cylinder hole opening side of the dust seal fitting groove, the inner peripheral surface of the annular base forms the non-contact surface to be not in contact with the outer peripheral surface of the piston Te, allowed to exist a gap between the inner peripheral surface and the outer peripheral surface of said piston of said annular base, the inner peripheral surface of the lip is in sliding contact with the outer peripheral surface of the piston Vehicle disc brake, characterized in that the sea urchin formed. The vehicle disc brake according to claim 1, wherein the lip portion is formed so as to be gradually thinner toward a tip side. The dust seal fitting groove has an annular recess formed at the opening end of the cylinder hole, and an L-shaped annular section that covers the cylinder hole opening end side of the annular recess and is fitted into the annular recess. The disc brake for a vehicle according to claim 1 or 2, wherein the disc brake is formed by a retainer. 4. The friction coefficient of a surface of the lip portion that is in sliding contact with the outer peripheral surface of the piston is set to be lower than a friction coefficient of the piston seal that is in sliding contact with the outer peripheral surface of the piston. The disc brake for vehicles according to claim 1. The cylinder hole is formed such that a diameter of an opening side cylinder portion on a cylinder hole opening side of the dust seal mounting groove is larger than a diameter of a cylinder hole on a cylinder hole bottom side of the dust seal mounting groove, and the dust seal The gap (E) formed between the inner peripheral surface of the annular base portion and the outer peripheral surface of the piston is narrower than the gap (X) formed between the opening-side cylinder portion and the outer peripheral surface of the piston, In addition, the gap is formed equal to or wider than the gap (Y) formed between the cylinder hole on the cylinder hole bottom side of the dust seal mounting groove and the outer peripheral surface of the piston. Item 5. The vehicle disc brake according to any one of Items 1 to 4.

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