JP2010133553A - Hydraulic vehicular disk brake - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic vehicular disk brake decreasing a roll-back amount and decreasing invalid stroke with a simple structure. <P>SOLUTION: A radial width dimension of a piston seal is set to 1.5-2.5 mm. A chamfer 9c is provided at a groove opening edge corner part on a cylinder hole opening side of a piston seal attachment groove 9. A length dimension B1 of the chamfer 9c in a direction of a cylinder hole axial line is set to in a range of 1/20 to 1/10 of a thickness dimension C1 in an axial-line direction of the piston seal 11. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a hydraulic vehicle disc brake, and more specifically, a piston for fluidly and movably supporting a piston in a piston seal mounting groove provided around an inner peripheral surface of a cylinder hole, and for causing the piston to roll back. The present invention relates to a hydraulic vehicle disc brake fitted with a seal.

  Conventionally, a piston seal with a square cross section (retraction) that supports a piston in a liquid-tight and movable manner in a piston seal mounting groove with a square cross section provided around the inner peripheral surface of the cylinder hole and rolls back the piston by a restoring force. There is known a hydraulic vehicle disc brake fitted with a ring (see, for example, Patent Document 1).

Japanese Patent No. 3218258

  However, in the above-described hydraulic vehicle disc brake, if the rollback amount of the piston seal is large, the invalid stroke at the initial stage of braking also increases, so that it is required to reduce the invalid stroke.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a hydraulic vehicle disc brake capable of reducing the rollback amount with a simple structure and reducing the invalid stroke.

  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, A hydraulic system in which a piston seal having a square cross section for supporting the piston in a liquid-tight and movable manner and rolling back the piston by a restoring force is fitted in a square-shaped piston seal mounting groove provided around the inner peripheral surface. In the disc brake for a vehicle, the first configuration is a groove opening on the cylinder hole opening side of the piston seal mounting groove after setting a radial width dimension of the piston seal to 1.5 mm or more and 2.5 mm or less. A chamfered portion is provided at the edge corner, and the length dimension of the chamfered portion in the axial direction of the cylinder hole is set to the thickness dimension in the axial direction of the piston seal. / 10 or less, is characterized in that set to 1/20 or more ranges.

  In the second configuration, a chamfered portion is provided at the groove opening edge corner of the piston seal mounting groove on the cylinder hole opening side, and the length of the chamfered portion in the cylinder hole radial direction is set to the radial direction of the piston seal. It is characterized by being set in a range of 1/10 or less and 1/20 or more with respect to the width dimension.

  The third configuration is characterized in that the rollback amount of the piston with respect to the axial dimension of the piston seal is set in a range of 1/40 or less and 1/70 or more.

  The fourth configuration is characterized in that the rollback amount of the piston with respect to the width dimension in the radial direction of the piston seal is set to a range of 1/40 or less and 1/70 or more.

  Furthermore, in each said structure, the diameter of the said piston is 20 mm or more and 40 mm or less, It is characterized by the above-mentioned.

  According to the hydraulic vehicle disc brake of the present invention, the radial width of the piston seal is set to 1.5 mm or more and 2.5 mm or less, and the groove opening edge angle of the piston seal mounting groove on the cylinder hole opening side is set. A chamfered portion is provided at the portion, and the length dimension of the chamfered portion in the axial direction of the cylinder hole is set within a range of 1/10 or less and 1/20 or more of the axial dimension of the piston seal. , Setting the length dimension of the chamfered portion in the cylinder hole radial direction to a range of 1/10 or less and 1/20 or more of the radial dimension of the piston seal, and the axial dimension of the piston seal. The rollback amount of the piston relative to the piston seal is set to a range of 1/40 or less and 1/70 or more. By setting, employing at least one of the, it is possible to reduce the amount of rollback. In particular, when the diameter of the piston is 20 mm or more and 40 mm or less, the rollback amount can be reduced, and since the rollback amount is small, the amount of hydraulic fluid required for braking can be reduced. The master cylinder that supplies hydraulic fluid to the hydraulic chamber can be downsized.

It is II sectional drawing of FIG. It is II-II sectional drawing of FIG. It is a front view of a disc brake showing an example of the present invention. It is a top view of a disk brake similarly. It is an expanded sectional view of a piston seal mounting groove similarly. It is a partially cutaway sectional view of the piston seal.

  1 to 6 show one embodiment of a hydraulic vehicle disc brake according to the present invention. FIG. 1 is a sectional view taken along the line II in FIG. 3, FIG. 2 is a sectional view taken along the line II-II in FIG. FIG. 4 is a plan view of the disc brake, FIG. 5 is an enlarged sectional view of the piston seal groove, and FIG. 6 is a partially cutaway sectional view of the piston seal.

  A hydraulic vehicle disc brake 1 shown in the present embodiment includes a disc rotor 2 that rotates in the direction of arrow A integrally with a wheel when the vehicle moves forward, and a caliper body 3 that is attached to the vehicle body at one side of the disc rotor 2. Friction pads 4, 4 arranged opposite to each other with the disk rotor 2 interposed therebetween.

  The caliper body 3 is a monocoque 4-pot piston facing type in which a pair of action portions 3a, 3a arranged opposite to each other with the disc rotor 2 interposed therebetween are integrally connected by a bridge portion 3b straddling the outer peripheral side of the disc rotor 2. Is formed. Mounting boss portions 3c, 3c in the disk radial direction are formed on both sides in the disk circumferential direction of one working portion 3a disposed outside the vehicle body, and mounting bolts inserted through the mounting boss portions 3c, 3c are disposed on the vehicle body side. The caliper body 3 is attached to the vehicle body by being screwed into the caliper attaching portion provided.

  Two cylinder holes 5 are formed in the action portions 3a and 3a so as to face each other. A piston 6 is accommodated in each cylinder hole 5 so as to be movable in the axial direction, and a hydraulic chamber 7 is defined between the cylinder hole 5 and the piston 6. The friction pad 4 is disposed between the two.

  The friction pad 4 includes a lining 4a that is in sliding contact with the side surface of the disk rotor 2, and a metal back plate 4b to which the lining 4a is attached. A disk shaft is attached to a hanging piece provided at the upper center of the back plate 4b. Direction hanger pins 8 are inserted and suspended on both sides of the disk rotor 2 so as to be movable in the disk axial direction.

  On the inner peripheral surface of each cylinder hole 5, an annular piston seal groove 9 is provided in the middle in the axial direction, and an annular dust seal mounting groove 10 is provided on the cylinder hole opening side of the piston seal mounting groove 9. It is installed. The piston seal mounting groove 9 is fitted with a piston seal 11 that is slidably contacted with the outer peripheral surface of the piston 6 in a liquid-tight and movable manner, and that rolls back the piston 6 with its restoring force. A dust seal 12 is slidably brought into sliding contact with the outer peripheral surface of the piston 6 to prevent dust from entering the cylinder hole.

  As shown in FIG. 5, the piston seal mounting groove 9 is formed as a conical surface having a bottom portion 9a that is an inclined surface that expands toward the opening side of the cylinder hole 5, and the cylinder hole opening side surface 9b is formed on the bottom portion 9a. It is formed of a gentle umbrella-shaped conical surface that forms an inclined surface that intersects the conical surface at a right angle. Further, a chamfered portion 9c inclined at a predetermined angle toward the cylinder hole opening side is provided at a groove opening edge corner portion of the cylinder hole opening side surface 9b of the piston seal mounting groove 9, and a groove opening edge corner portion of the cylinder hole bottom side surface 9d is provided. In addition, an inclined portion 9e is provided which is inclined at a predetermined angle toward the cylinder hole bottom side and allows elastic deformation of the piston seal 11 when the piston 6 is pushed into the cylinder hole 5. The depth of the piston seal mounting groove 9 is slightly smaller than the width dimension of the piston seal 11 in the radial direction, and the diameter of the bottom 9a is within the range where the piston seal 11 is mounted in the piston seal mounting groove 9. Slightly smaller than outer diameter. Furthermore, the groove width (dimension in the cylinder axial direction) is set to be larger than the width dimension (length in the axial direction) of the piston seal 11.

  On the other hand, as shown in FIG. 6, the piston seal 11 has a quadrangular cross section called a square seal, and has a quadrilateral cross section including sides along the radial direction and the axial direction. When the piston seal 11 is fitted into the piston seal mounting groove 9 formed in the cross-sectional shape as described above, the diameter of the bottom 9a is slightly smaller than the outer diameter of the piston seal 11, and the bottom 9a expands in the cylinder hole opening direction. Since it has an open conical surface, the piston seal 11 is slightly deformed so that the outer peripheral surface 11a of the piston seal 11 and the bottom 9a of the piston seal mounting groove 9 are in close contact with each other. The cylinder hole opening side surface 9b of the groove 9 is in close contact.

  When the hydraulic fluid (brake fluid) increased in pressure is supplied to the hydraulic chamber 7 of the caliper body 3 by the braking operation of the driver, the piston 6 moves forward in the cylinder hole 5 in the opening direction (disc rotor direction), and each friction The pads 4 and 4 are pushed in the direction of the disk rotor 2, the lining 4 a of each friction pad 4 is pressed against the side surface of the disk rotor 2, and a braking force acts on the disk rotor 2.

  The forward movement of the piston 6 during braking causes the inner peripheral surface 11b of the piston seal 11 to be dragged to the outer peripheral surface of the piston 6, and the cylinder hole opening side surface of the piston seal is in contact with the chamfered portion 9c. The outer peripheral side of the piston seal mounting groove 9 is elastically deformed so as to come into contact with the cylinder hole opening side surface 9b.

  When the pressure in the hydraulic chamber 7 decreases due to the release of the braking operation, the piston 6 rolls back due to the restoring force of the piston seal 11 returning to its original shape. This rollback amount corresponds to the amount of deformation in which the inner peripheral portion of the piston seal 11 is elastically deformed toward the cylinder hole opening side. Therefore, the axial dimension thickness C1 of the piston seal 11 and the radial direction of the piston seal 11 are the same. It is possible to optimize the width dimension C2 by appropriately setting the shape and dimensions of the piston seal mounting groove 9, for example, the angle of the chamfered portion 9c with respect to the cylinder hole opening side surface 9b and the radial dimension. it can.

  In particular, in order to reduce the rollback amount, the radial width dimension C2 of the piston seal 11 is set to 1.5 mm or more and 2.5 mm or less, and preferably, the piston seal 11 is set to a dimension of about 2 mm square, In this embodiment, the length C1 of the chamfered portion 9c in the cylinder hole axial direction is set to a range of 1/10 or less and 1/20 or more of the thickness C1, and the cylinder of the chamfered portion 9c is set. The length dimension B2 in the hole diameter direction is set to a range of 1/10 or less and 1/20 or more with respect to the width dimension C2, and the rollback amount of the piston 6 is 1 / less than the thickness dimension C1. The range is set to 40 or less and 1/70 or more, and is set to 1/40 or less and 1/70 or more with respect to the width C2.

  By setting in this way, the rollback amount that the piston 6 rolls back when releasing the brake can be reduced, and at the same time, the piston seal mounting groove 9 can be reduced, and as a result, the caliper body 3 including the cylinder hole 5 can be downsized. be able to. Furthermore, since the rollback amount is small, the amount of hydraulic fluid required for braking is small, and the master cylinder that supplies the hydraulic fluid to the hydraulic chamber 7 can be downsized.

  In addition, the relationship between the piston seal mounting groove of the present invention, the piston seal, and the rollback amount of the piston is determined by setting the radial width dimension of the piston seal to 1.5 mm or more and 2.5 mm or less. The cylinder bore axial length dimension is set to a range of 1/10 or less and 1/20 or more of the axial dimension of the piston seal in the axial direction. Is set to a range of 1/10 or less and 1/20 or more of the radial dimension of the piston seal, and the rollback amount of the piston with respect to the axial dimension of the piston seal is 1/40 or less, 1 / 70 or more, and the piston rollback amount with respect to the radial width of the piston seal is set to 1/40 or less and 1/70 or more. Obtain a great effect by the but can be expected predetermined effect alone employs at least any one. Further, the shape of the piston seal groove is not limited to this embodiment. For example, the angle of the chamfered portion can be arbitrarily set, and the piston seal width dimension for which the piston seal tightening margin is set. And the depth dimension of the bottom of the piston seal groove can be arbitrarily set. Further, the present invention is not limited to the piston brake type monocoque disc brake as in the above-described embodiment, and can be applied to any type of disc brake.

  DESCRIPTION OF SYMBOLS 1 ... Hydraulic type vehicle disc brake, 2 ... Disc rotor, 3 ... Caliper body, 3a ... Action part, 3b ... Bridge part, 3c ... Mounting boss part, 4 ... Friction pad, 4a ... Lining, 4b ... Back plate, 5 ... Cylinder hole, 6 ... Piston, 7 ... Hydraulic chamber, 8 ... Hanger pin, 9 ... Piston seal mounting groove, 9a ... Bottom part, 9b ... Cylinder hole opening side face, 9c ... Chamfering part, 9d ... Cylinder hole bottom side face, 9e ... inclined portion, 10 ... dust seal mounting groove, 11 ... piston seal, 11a ... outer peripheral surface, 11b ... inner peripheral surface, 12 ... dust seal

Claims (5)

  A piston that pushes the friction pad toward the side surface of the disk rotor is inserted into a cylinder hole formed in the caliper body, and the piston seal mounting groove having a square cross section provided around the inner peripheral surface of the cylinder hole has the piston. In a hydraulic vehicle disc brake fitted with a piston seal having a square cross section that supports the fluid tightly and movably, and rolls back the piston by a restoring force, the width dimension in the radial direction of the piston seal is 1. Set to 5 mm or more and 2.5 mm or less, and provided a chamfered portion at the groove opening edge corner of the piston seal mounting groove on the cylinder hole opening side, and the length dimension of the chamfered portion in the cylinder hole axial direction, A hydraulic vehicle disk breaker characterized in that it is set within a range of 1/10 or less and 1/20 or more of the axial dimension of the piston seal. .   A piston that pushes the friction pad toward the side surface of the disk rotor is inserted into a cylinder hole formed in the caliper body, and the piston seal mounting groove having a square cross section provided around the inner peripheral surface of the cylinder hole has the piston. In a hydraulic vehicle disc brake fitted with a piston seal having a square cross section that supports the fluid tightly and movably, and rolls back the piston by a restoring force, the width dimension in the radial direction of the piston seal is 1. 5 mm or more and 2.5 mm or less, a chamfered portion is provided at the groove opening edge corner on the cylinder hole opening side of the piston seal mounting groove, and the length dimension of the chamfered portion in the cylinder hole radial direction is A hydraulic type vehicle disc brake characterized in that it is set in a range of 1/10 or less and 1/20 or more with respect to the radial width of the piston seal.   A piston that pushes the friction pad toward the side surface of the disk rotor is inserted into a cylinder hole formed in the caliper body, and the piston seal mounting groove having a square cross section provided around the inner peripheral surface of the cylinder hole has the piston. In a hydraulic vehicle disc brake fitted with a piston seal having a square cross section that supports the fluid tightly and movably, and rolls back the piston by a restoring force, the width dimension in the radial direction of the piston seal is 1. While being set to 5 mm or more and 2.5 mm or less, the rollback amount of the piston with respect to the thickness dimension in the axial direction of the piston seal is set to a range of 1/40 or less and 1/70 or more. Hydraulic disc brake for vehicles.   A piston that pushes the friction pad toward the side surface of the disk rotor is inserted into a cylinder hole formed in the caliper body, and the piston seal mounting groove having a square cross section provided around the inner peripheral surface of the cylinder hole has the piston. In a hydraulic vehicle disc brake fitted with a piston seal having a square cross section that supports the fluid tightly and movably, and rolls back the piston by a restoring force, the width dimension in the radial direction of the piston seal is 1. A hydraulic type vehicle disc brake characterized in that it is set to 5 mm or more and 2.5 mm or less, and the rollback amount of the piston with respect to the width dimension is set to a range of 1/40 or less and 1/70 or more. 5. The hydraulic vehicle disc brake according to claim 1, wherein the piston has a diameter of 20 mm or more and 40 mm or less.

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