JP4318575B2 - Hydraulic vehicle disc brake - Google Patents

Description

  The present invention relates to a hydraulic vehicle disc brake, and more specifically, a hydraulic vehicle including a piston seal between an inner peripheral surface of a cylinder hole and an outer peripheral surface of a piston, and a friction pad side of the piston protruding from an opening of the cylinder hole. Disc brake for use.

  A hydraulic disk brake for a vehicle is a pressure which is slidably inserted into a bottomed cylinder hole opened on the disk rotor side, and is supplied to a hydraulic chamber defined between the piston and the bottom of the cylinder hole. The piston is moved toward the disk rotor by the liquid, and the braking force is obtained by pressing the friction pad against the side surface of the disk rotor with the piston. The inner peripheral surface of the cylinder hole is in sliding contact with the outer peripheral surface of the piston to hold the piston in a fluid-tight and movable manner, and the piston after releasing the braking force is rolled back by a predetermined amount so that a gap between the friction pad and the disk rotor is provided. A piston seal having a function of automatic adjustment is provided.

In such a vehicle hydraulic disc brake, high-temperature braking heat generated by the sliding contact between the disc rotor and the friction pad is transmitted to the piston through the friction pad, and the brake fluid in the caliper body may be heated. For this reason, a heat insulating plate is interposed between the friction pad and the piston (for example, see Patent Document 1).
Japanese Patent Laid-Open No. 11-30257

  However, in the case where the heat insulating plate is provided as described above, the number of parts increases, the cost required for processing and assembly of each member increases, the weight of the piston increases, and the slidability of the piston is impaired, In some cases, the overall weight of the disc brake was increased.

  SUMMARY OF THE INVENTION Accordingly, the present invention provides a hydraulic vehicle disk brake that can naturally cool a piston with an extremely simple structure and can prevent the brake fluid from becoming hot even when braking heat is transmitted from the friction pad to the piston. It is an object.

In order to achieve the above object, a hydraulic vehicle disc brake according to the present invention includes a piston that pushes a friction pad toward a side surface of a disc rotor in a cylinder hole formed in a caliper body, and the friction pad side is disposed on the friction pad side. A hydraulic vehicle disc having a piston seal that is inserted in a state of protruding from the cylinder hole and that holds the piston in a fluid-tight and movable manner between the inner peripheral surface of the cylinder hole and the outer peripheral surface of the piston. In the brake, the caliper body has a monocoque structure in which a pair of action portions disposed on both side portions of the disk rotor are integrally formed at both ends of the bridge portion straddling the outer periphery of the disk rotor, and the piston is configured so that the disk rotor sandwiched therebetween an opposed piston type which is opposed, projecting amount of the piston has an opening surface and cylinder of the cylinder bore The dimension between the friction pad side of the distal end surface of the piston 7 which protrudes from the hole, is set larger than the dimension between the opening surface of the piston seal the opening side surface and the cylinder bore, the piston seal of the bottom wall The dimension between the side surface and the rear end surface on the cylinder hole bottom wall side of the piston is such that the outer peripheral surface of the piston is in sliding contact with the piston seal during braking when the friction pad lining is worn to the limit of use. It is characterized in that it is set to a dimension to be held .

  Further, the dimension between the opening side surface of the piston seal and the cylinder hole opening surface is the dimension when the piston seal is not deformed when the piston is not operated, or the piston seal is deformed when the piston is operated. The dimension between the opening surface of the cylinder hole and the front end surface of the piston protruding from the cylinder hole includes a dimension when the friction pad is in a new state.

  According to the hydraulic vehicle disc brake of the present invention, since the piston protrudes greatly from the cylinder hole, the piston can be naturally cooled by the traveling wind. Therefore, since a member such as a heat insulating plate is not required, the cost required for the processing and assembly of the member can be reduced. Furthermore, since the amount of piston insertion into the cylinder hole is reduced, in particular, in the case of a caliper body with a piston-facing monocoque structure in which the caliper body is integrally formed continuously on both sides of the bridge portion, the piston is removed from the cylinder hole. Since the depth of the cylinder hole can be made smaller than before by making it project greatly, the machining of the cylinder hole can be easily performed by increasing the distance between the caliper bodies facing each other across the disk rotor.

  1 and 2 show an embodiment in which the hydraulic vehicle disc brake of the present invention is applied to a monocoque radial mount type piston-facing caliper body. FIG. 1 is a cross-sectional view taken along the line II in FIG. FIG. 2 is a front view of the caliper body.

  The hydraulic vehicle disc brake 1 includes a disc rotor 2 that rotates integrally with a wheel (not shown), a piston-facing caliper body 3 fixed to a vehicle body at one side of the disc rotor 2, and the caliper body. 3 includes a pair of friction pads 4 and 4 disposed to face each other with the disk rotor 2 interposed therebetween.

  The friction pad 4 is formed by a lining 4a that is in sliding contact with the side surface of the disc rotor 2, and a back plate 4b that is held by the caliper body 3. The through hole 4c through which the hanger pin 5 is inserted is formed in the back plate 4b. Is provided. The friction pad 4 has the hanger pin 5 inserted into the through hole 4c and the disc rotor 2 is sandwiched between both ends of the back plate accommodated in a torque receiving portion (not shown) provided in the caliper body 3. It is suspended so as to be movable in the disk axial direction and is urged toward the disk center by a pad spring 6 mounted on the bridge portion 3a.

  The caliper body 3 is a monocoque body in which a pair of action portions 3b and 3b disposed on both sides of the disc rotor 2 are integrally formed at both ends of the bridge portion 3a straddling the outer periphery of the disc rotor 2. A union hole 3c and a bleeder hole 3d are provided in the disk outer peripheral direction, and a pair of vehicle body mounting bosses 3e are provided at both ends in the disk inner peripheral direction. Two bottomed cylinder holes 3f and 3f are provided in each acting portion 3b and 3b so as to face each other, and a cup-shaped piston 7 is provided in each cylinder hole 3f with a piston seal 8 and a dust seal 9 respectively. A fluid pressure chamber 10 is defined between the cylinder wall 3f and the bottom wall of the cylinder hole 3f.

  The piston seal 8 is fitted into a piston seal mounting groove 3g that is provided at a position closer to the opening side than the intermediate portion of the cylinder hole 3f, and is tightly fitted between the piston 7 to provide a fluid-tight seal. When the piston 7 is braked forward through the cylinder hole 3f in the direction of the disk rotor, the piston 7 is elastically deformed accordingly, and when the braking operation is released, the piston 7 is rolled back by a predetermined amount by the restoring force. A dust seal mounting groove 3h is provided around the opening end of the cylinder hole 3f, and the dust seal 9 is fitted into the dust seal mounting groove 3h and sealed between the piston 7 by the dust seal 9, so that the cylinder hole 3f and the piston 7 are sealed. It prevents dust and earth and sand from entering between.

  The cylinder hole 3f provided in the action portion 3b is integrally formed as a cast hole for the cylinder hole that leaves a machining allowance when the caliper body 3 is cast, and after the caliper body 3 is formed, the cylinder hole 3f is cast. The hole is cut to a predetermined size as a cylinder hole 3f by a cutting device. The piston seal mounting groove 3g and the dust seal mounting groove 3h are cut to a predetermined size by inserting a cutting tool into the cylinder hole 3f. The piston 7 is inserted into the cylinder hole 3f after the piston seal 8 and the dust seal 9 are fitted into the piston seal mounting groove 3g and the dust seal mounting groove 3h, respectively.

  The pistons 7 are respectively inserted into the cylinder holes 3f with the friction pad 4 side protruding from the cylinder holes 3f. The projecting amount of the piston 7 is the dimension D1 between the opening surface 3i of the cylinder hole 3f and the tip surface 7a on the friction pad side of the piston 7 projecting from the cylinder hole 3f, and the opening side surface 8a of the piston seal 8. And the dimension D2 between the opening 3i of the cylinder hole 3f. Further, the dimension D3 between the bottom wall side surface 8b of the piston seal 8 and the rear end surface 7b of the piston 7 on the cylinder wall bottom wall side is determined during braking operation in a state where the lining 4a of the friction pad 4 is worn to the use limit. The piston 7 is set so that the outer peripheral surface of the piston 7 is securely held in sliding contact with the piston seal 8. The dimension D2 between the opening side surface 8a of the piston seal 8 and the opening surface 3i of the cylinder hole 3f is the dimension when the piston seal 8 is not deformed when the piston is not operated, or the piston when the piston is operated. Either of the dimensions when the seal 8 is deformed may be used.

  In this way, by causing the friction pad 4 side of the piston 7 to largely protrude from the cylinder hole 3f, the piston 7 can be naturally cooled by outside air such as traveling wind, and the sliding contact between the disk rotor 2 and the friction pad 4 Even if the generated high-temperature braking heat is transmitted to the piston 7 through the friction pad 4, the piston 7 does not reach a high temperature state, and therefore, the brake fluid in the caliper body is not heated. Moreover, since it is not necessary to add members, such as a heat insulation board, the cost which a process and assembly of a member require can be reduced.

  Furthermore, since the weight of the piston 7 does not increase due to the addition of a member such as a heat insulating plate, the slidability of the piston 7 is not impaired. In particular, in the case of a piston-facing caliper body in which the caliper bodies are disposed opposite to each other on both sides of the bridge portion 3a across the outside of the disc rotor 2, the number of pistons 7 is two or more (in this embodiment, 4). Therefore, the cost required for processing and assembling the members can be further reduced.

  In addition to this, in a monocoque piston-facing caliper body in which a pair of caliper bodies are integrally formed continuously on both sides of the bridge portion, the friction pad 4 side of the piston 7 is greatly protruded from the cylinder hole 3f, The amount of piston insertion into the cylinder hole 3f can be relatively reduced. In particular, the dimension D3 between the bottom wall side surface 8B of the piston seal 8 and the rear end surface 7b of the piston hole bottom wall side of the piston 7 is By setting the minimum dimension in consideration of the use limit of the lining 4a, the depth of the cylinder hole 3f can be made smaller than before, so the distance between the caliper bodies facing each other across the disk rotor, that is, the opening surface of the cylinder hole 3f The interval between 3i can be widened. Thereby, it is possible to easily insert a cutting device for cutting the cylinder hole 3f after forming the caliper body 3 and a cutting tool for cutting the piston seal mounting groove 3g and the dust seal mounting groove 3h. In addition, it is possible to improve the processing capability by forming a cutting device or a cutting tool larger than before, and the productivity can be improved.

1 is a cross-sectional view taken along the line II of FIG. It is a front view of the caliper body which shows one example of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Hydraulic type vehicle disc brake, 2 ... Disc rotor, 3 ... Caliper body, 3a ... Bridge part, 3b ... Action part, 3c ... Union hole, 3d ... Breeder hole, 3e ... Body mounting boss part, 3f ... Cylinder Hole, 3g ... piston mounting groove, 3h ... dust seal mounting groove, 3i ... opening, 4 ... friction pad, 4a ... lining, 4b ... back plate, 4c ... through hole, 5 ... hanger pin, 6 ... pad spring, 7 ... Piston, 7a ... front end surface, 7b ... rear end surface, 8 ... piston seal, 8a ... opening side surface, 8b ... bottom wall side surface, 9 ... dust seal, 10 ... hydraulic chamber, D1 ... opening surface of cylinder hole and piston Dimension between tip surface, D2 Dimension between opening side surface of piston seal and opening surface of cylinder hole, D3 Dimension between bottom wall side surface of piston seal and rear end surface of piston

Claims (4)

A piston that pushes the friction pad toward the side surface of the disc rotor is inserted into a cylinder hole formed in the caliper body with the friction pad side protruding from the cylinder hole, and the inside of the cylinder hole In a hydraulic vehicle disc brake in which a piston seal that holds the piston in a fluid-tight and movable manner is disposed between the peripheral surface and the outer peripheral surface of the piston , both ends of the bridge portion where the caliper body straddles the outer periphery of the disc rotor In addition, it is a monocoque structure in which a pair of action portions disposed on both sides of the disk rotor are integrally formed, and is a piston-facing type in which the piston is disposed to face the disk rotor, and the protruding amount of the piston is , The dimension between the opening surface of the cylinder hole and the tip surface on the friction pad side of the piston 7 protruding from the cylinder hole, Serial set larger than the dimension between the opening surface of the piston seal the opening side surface and the cylinder bore, the dimension between the rear end surface of the cylinder hole bottom wall side of the bottom wall side surface of the piston seal piston The hydraulic vehicle disc is characterized in that the outer peripheral surface of the piston during braking operation in a state where the lining of the friction pad is worn to the use limit is held in sliding contact with the piston seal. brake.   2. The hydraulic type according to claim 1, wherein the dimension between the opening side surface of the piston seal and the cylinder hole opening surface is a dimension when the piston seal is not deformed when the piston is not operated. Disc brake for vehicles.   2. The hydraulic vehicle disc brake according to claim 1, wherein the dimension between the opening side surface of the piston seal and the cylinder hole opening surface is a dimension in which the piston seal is deformed when the piston is operated. .   The dimension between the opening surface of the cylinder hole and the tip surface of the piston protruding from the cylinder hole includes a dimension when the friction pad is in a new state. The hydraulic vehicle disc brake described.

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