JP6470577B2 - Vehicle disc brake - Google Patents

Description

  The present invention relates to a vehicle disc brake, and more specifically, a piston seal groove is provided in a cylinder hole formed in a working portion of a caliper body, and the piston is inserted into the cylinder hole via a piston seal fitted in the piston seal groove. The present invention relates to a vehicle disc brake interpolated in

  Conventionally, in a vehicle disc brake in which a piston is inserted into a cylinder hole via a piston seal, high-temperature braking heat generated during braking may be transmitted to the piston seal via the piston. When the brake is released, the piston is dragged and moved in the direction of the hydraulic pressure chamber to a predetermined amount or more when the brake is released, and the stroke of the piston at the time of the next braking is increased and the brake feeling may be deteriorated.

  For this reason, on the bottom wall of the piston seal groove, a diameter-enlarged portion that expands toward the cylinder hole opening side, and a circumference that is located closer to the cylinder hole bottom side than the enlarged-diameter portion and has a smaller inclination angle than the enlarged-diameter portion When the piston seal is thermally expanded, the volume change of the piston seal is absorbed by the peripheral surface portion and the rollback amount of the piston is adjusted (for example, refer to Patent Document 1), or the piston seal is attached to the piston. A section having a narrower cross-section than the seal groove, or an oval shape, and defining a space for absorbing thermal expansion between the piston seal and the piston seal groove (see, for example, Patent Document 2). )was there.

Japanese Patent No. 4126428 JP-A-11-125284

  However, in the above-mentioned Patent Document 1, when the piston seal is thermally expanded, the volume change is concentrated on the bottom side of the cylinder hole where the peripheral surface portion is formed, and when releasing the brake, the piston is moved in the hydraulic chamber direction by a predetermined amount or more. There was a risk of dragging and moving. Furthermore, since a corner portion is formed between the enlarged diameter portion and the peripheral surface portion, a portion of the piston seal that is significantly deformed occurs when the piston seal expands, which may reduce the durability of the piston seal. It was. Further, in the above-mentioned Patent Document 2, since the piston seal is formed in a circular cross section or an oval shape, the contact area with the piston is smaller than that of the square seal, and the piston is reliably rolled back. There was a possibility that it could not be done.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a vehicle disc brake capable of appropriately rolling back a piston with a piston seal when braking is released even when the piston seal is expanded by high-temperature braking heat generated during braking. .

In order to achieve the above object, a vehicle disc brake according to the present invention has a caliper body in which an operating portion of a caliper body is provided with a cylinder hole opened on the disc rotor side, and a piston seal groove is provided in the cylinder hole, and the piston seal groove is provided. In a vehicle disc brake in which a piston seal formed by a square seal is fitted and the piston is inserted into a cylinder hole via the piston seal, the piston seal groove has a cylinder hole opening side wall and a cylinder hole bottom side wall. And a bottom wall connecting the cylinder hole bottom side wall and the cylinder hole opening side wall, the bottom wall having a parabolic cross-sectional shape in which the depth of the groove gradually increases toward the cylinder hole opening side. The piston seal in an initial state that is not thermally expanded includes at least a cylinder hole bottom side wall of the piston seal groove and the piston seal. And between Le, between the cylinder bore open side of the bottom wall of the piston seal groove and the piston seal, the space portion to allow thermal expansion of the piston seal is provided, the bottom wall, the curved portion to the cylinder bore bottom portion side, parallel to the cross-sectional shape cylinder axis, or is characterized that you have provided a straight portion the depth of the piston seal groove becomes gradually deeper toward the cylinder bore bottom side.

  Also, a cylinder hole is provided in the working portion of the caliper body so as to open to the disk rotor side, a piston seal groove is provided in the cylinder hole, and a piston seal formed by a square seal is fitted into the piston seal groove. In the vehicle disc brake in which the piston is inserted into the cylinder hole via the piston seal, the piston seal groove includes a cylinder hole opening side wall, a cylinder hole bottom side wall, the cylinder hole bottom side wall, and the cylinder hole opening side wall. And a plurality of projecting arcs having different curvatures with a groove having a depth gradually increasing toward the cylinder hole opening side. Includes a curved portion having a continuous shape, and the piston seal in an initial state that is not thermally expanded includes at least a cylinder hole bottom side wall of the piston seal groove and the piston seal groove. And between the piston seal, between the cylinder bore open side of the bottom wall of the piston seal groove and the piston seal, the space portion to allow thermal expansion of the piston seal is characterized in that it is provided.

  Further, it is preferable that the plurality of projecting arcs having different curvatures have a smaller curvature as the arc arranged on the cylinder hole opening side. Further, the bottom wall includes a linear portion on the cylinder hole bottom side of the curved portion, the cross-sectional shape of which is parallel to the cylinder shaft, or the depth of the piston seal groove gradually increases toward the cylinder hole bottom side. Further, a bottom side curved portion in which the depth of the piston seal groove gradually increases toward the cylinder hole bottom side may be provided.

  According to the vehicle disc brake of the present invention, the space that allows thermal expansion of the piston seal formed by the square seal is at least between the cylinder hole bottom side wall of the piston seal groove and the piston seal, and the piston seal groove. Since the piston seal is provided between the cylinder hole opening side of the bottom wall and the piston seal, the thermal expansion of the piston seal can be absorbed by the cylinder hole bottom side and the cylinder hole opening side of the piston seal groove. Thus, when the piston seal expands, only the cylinder hole bottom side is not significantly deformed. As a result, it is possible to prevent the piston from being dragged and moved more than a predetermined amount in the direction of the hydraulic pressure chamber when the brake is released, and there is no possibility that the stroke of the piston at the time of the next braking increases, and the brake feeling is kept good. be able to.

  Furthermore, a curved portion having a parabolic cross-sectional shape in which the depth of the groove gradually increases toward the cylinder hole opening side on the bottom wall of the piston seal groove, a circular arc shape having a projecting cross section, or a cylinder hole opening By forming a curved portion having a shape in which a plurality of projecting arcs with different curvatures are continuously formed, the depth of the groove gradually increases toward the side, and the piston seal expands partially. Since the location is difficult to occur, the rollback amount of the piston can be properly maintained and the durability of the piston seal can be improved.

  In addition, since the piston seal groove is shallow on the bottom side of the cylinder hole, the tightening force on the bottom side of the cylinder hole of the piston seal is increased, and the position of the piston seal in the piston seal groove can be maintained. Since it can do, the space part between the cylinder hole bottom side wall of a piston seal groove and a piston seal can be kept favorable.

  Furthermore, on the cylinder hole bottom side of the curved portion, the cross-sectional shape is parallel to the cylinder axis, or the piston seal groove depth is gradually increased toward the cylinder hole bottom side, or toward the cylinder hole bottom side. By providing a bottom-side curved portion in which the piston seal groove gradually increases in depth, the piston seal groove is not significantly deformed partly when the piston seal expands, and the piston seal groove has a cylinder hole bottom side wall and the piston seal. The volume of the space portion can be secured.

It is a principal part expanded sectional view of the disc brake for vehicles which shows the 1st example of this invention. It is an expanded sectional view which similarly shows a piston seal groove. It is a sectional view of a disk brake for vehicles similarly. It is a principal part expanded sectional view of the disc brake for vehicles which shows the 2nd form example of this invention.

  1 to 3 are views showing a first embodiment of a vehicle disc brake of the present invention. The vehicle disc brake 1 according to the present embodiment includes an action portion 3 a provided on one side portion of the disc rotor 2, a reaction portion 3 b provided on the other side portion of the disc rotor 2, and these components. A caliper body 3 having a bridge portion 3c connected across the outside is fixed to the vehicle body via a slide pin (not shown) and a caliper bracket 4.

  A pair of friction pads 5, 5 disposed opposite to both sides of the disk rotor 2 are formed by a lining 5 a that is in sliding contact with the side surface of the disk rotor 2 and a back plate 5 b that is held by the caliper body 3. Inside the bridge portion 3c, the disc rotor 2 is sandwiched between the action portion 3a and the reaction portion 3b so as to be movable in the disc axial direction.

  The action portion 3a of the caliper body 3 is provided with a bottomed cylinder hole 6 opened on the disk rotor 2 side, and a cup-shaped piston 7 is inserted into the cylinder hole 6 so as to be liquid-tight and movable. ing. The piston 7 is moved in the cylinder hole 6 toward the disk rotor by the working fluid supplied to the hydraulic chamber 8 defined between the piston 7 and the bottom of the cylinder hole 6, and is a friction pad on the working part side. 5 is pushed toward one side of the disk rotor 2. The reaction portion 3b is provided with a reaction force claw 3d that pushes the friction pad 5 on the reaction portion side toward the other side surface of the disk rotor 2.

  On the inner peripheral surface of the cylinder hole 6, an annular piston seal groove 9 is provided in the middle in the cylinder axial direction, and an annular dust seal groove 10 is provided on the cylinder hole opening side of the piston seal groove 9. ing. The piston seal groove 9 is fitted with a piston seal 11 that is slidably contacted with the outer peripheral surface of the piston 7 in a fluid-tight manner, and the dust seal groove 10 has one end of a dust seal 12 that prevents dust from entering the cylinder hole. Is fitted, and the other end of the dust seal 12 is fitted in a fitting groove 7 a provided around the outer peripheral surface of the tip of the piston 7.

  The piston seal groove 9 has a cylinder hole opening side wall 9a, a cylinder hole bottom side wall 9b, and a bottom wall 9c connecting the cylinder hole bottom side wall 9b and the cylinder hole opening side wall 9a. The cylinder hole opening side wall 9a is provided on the groove opening side, on the first conical surface 9d that gradually inclines toward the groove opening end toward the groove opening end, on the groove bottom side of the first conical surface 9d, and on the cylinder shaft CL1. And a second conical surface 9f that is provided on the groove bottom side of the plane portion 9e and that gradually inclines toward the groove bottom toward the cylinder hole opening side. The cylinder hole bottom side wall 9b is formed perpendicular to the cylinder axis CL1, and a third conical surface 9g is provided on the groove opening side, which gradually inclines toward the cylinder hole bottom side toward the groove opening end.

  The bottom wall 9c is formed in a parabolic cross-sectional shape, the apex P1 of the parabola is provided in the vicinity of the cylinder hole bottom side wall 9b, and the depth of the groove gradually increases from the apex P1 toward the cylinder hole opening side wall 9a. A portion 9h is formed, and a bottom-side curved portion 9i in which the depth of the groove gradually increases from the apex P1 toward the cylinder hole bottom side wall 9b is formed.

  The piston seal 11 has a quadrangular cross section, also called a square seal, and the cylinder hole opening side surface 11b is brought into contact with the flat surface portion 9e of the cylinder hole opening side wall 9a of the piston seal groove 9 to The corner portion 11c is disposed at the position of the apex P1 of the bottom wall 9c and is fitted into the piston seal groove 9, and the space E1 is located between the cylinder hole bottom side wall 9b of the piston seal groove 9 and the piston seal 11 in the second position. A space E2 is formed between the conical surface 9f and the piston seal 11, and a space E3 is formed between the cylinder hole opening side of the curved portion 9h and the piston seal 11.

  In the vehicular disc brake 1 of the present embodiment formed as described above, when the hydraulic fluid is supplied to the hydraulic pressure chamber 8 of the caliper body 3 by the driver's braking operation, the piston 7 moves into the cylinder hole 6. Is moved forward in the direction of the disk rotor, and the friction pad 5 on the action side is pushed in the direction of the disk rotor 2, and the lining 5 a of the friction pad 5 is pressed against one side of the disk rotor 2. Next, by this reaction part, the caliper body 3 moves in the direction of the action part 3a by the guide of the slide pin, the reaction force claw 3d of the reaction part 3b pushes the friction pad 5 on the reaction part side, and the friction pad 5 is pressed against the other side of the disk rotor 2. Thereby, the braking force of the disk rotor 2 acts.

  At the time of braking, the piston seal 11 is deformed to the first conical surface 9d side by dragging the inner peripheral surface 11a to the outer peripheral surface 7b of the piston 7 by the advance of the piston 7. Further, when high-temperature braking heat generated during braking is transmitted to the piston seal 11 via the piston 7 and the piston seal 11 is thermally expanded in the piston seal groove 9, the volume of the expanded piston seal 11 is changed to the piston seal groove 9. Are absorbed by spaces E1, E2, and E3 formed on the cylinder hole opening side and the cylinder hole bottom side, respectively. At this time, since the bottom wall 9c of the piston seal groove 9 gradually increases in depth toward the cylinder hole opening side and has a parabolic cross-sectional shape, the piston seal 11 is partially deformed significantly. It is hard to produce a place.

  Further, when the pressure in the hydraulic chamber 8 decreases due to the release of the braking operation, the piston 7 rolls back a predetermined amount by the restoring force that returns the piston seal 11 to the original state. At this time, in this embodiment, unlike the conventional case, when the piston seal 11 is expanded, only the cylinder hole bottom side is not significantly deformed. Therefore, when releasing the brake, the piston 7 is moved in the hydraulic chamber direction by a predetermined amount or more. Therefore, there is no possibility that the stroke of the piston 7 at the time of the next braking increases, and the brake feeling can be kept good. Further, since the piston seal groove 9 has a shallow depth on the bottom side of the cylinder hole, the tightening force on the bottom side of the cylinder hole of the piston seal 11 increases, and the position of the piston seal 11 in the piston seal groove 9 is increased. It can hold | maintain and can maintain space part E1, E2, E3 favorably. Furthermore, when the piston seal 11 is thermally expanded, it is difficult to generate a portion that is partially remarkably deformed, so that the durability of the piston seal 11 can be improved.

  FIG. 4 shows a second embodiment of the present invention. Components that are the same as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. The bottom wall 9j of the piston seal groove 9 of the present embodiment is formed in a circular arc shape having a projecting cross section, and a vertex P2 is provided in the vicinity of the cylinder hole bottom side wall 9a, from the vertex P2 toward the cylinder hole opening side wall 9a. Thus, a curved portion 9k having a gradually increasing groove depth is formed, and a bottom side curved portion 9m having a gradually increasing groove depth from the apex P2 toward the cylinder hole bottom side wall 9b is formed.

  The present invention is not limited to the above-described embodiment, and the bottom wall of the piston seal groove may include a curved portion having a cross-sectional shape in which a plurality of projecting arcs having different curvatures are continuous. In this case, it is preferable that the plurality of projecting arcs having different curvatures have a smaller curvature as the arc arranged on the cylinder hole opening side. Also, the cross-sectional shape of the bottom wall of the piston seal groove is the cylinder shaft on the cylinder hole bottom side of the curved portion having a parabolic cross-sectional shape or the curved portion having a cross-sectional shape in which a plurality of projecting arcs having different curvatures are continuous. Or a linear portion where the piston seal groove gradually becomes deeper toward the bottom of the cylinder hole. Further, the present invention is not limited to being applied to a pin slide type disc brake as in the above-described embodiment, but can also be applied to a piston facing type disc brake.

DESCRIPTION OF SYMBOLS 1 ... Vehicle disc brake, 2 ... Disc rotor, 3 ... Caliper body, 3a ... Action part, 3b ... Reaction part, 3c ... Bridge part, 3d ... Reaction force claw, 4 ... Caliper bracket, 5 ... Friction pad, 5a ... Lining, 5b ... back plate, 6 ... cylinder hole, 7 ... piston, 7a ... fitting groove, 7b ... outer peripheral surface, 8 ... hydraulic chamber, 9 ... piston seal groove, 9a ... cylinder hole opening side wall, 9b ... cylinder hole Bottom side wall, 9c ... bottom wall, 9d ... first conical surface, 9e ... flat portion, 9f ... second conical surface, 9g ... third conical surface, 9h ... curved portion, 9i ... bottom side curved portion, 9j ... bottom wall , 9k ... curved portion, 9m ... bottom side curved portion, 10 ... dust seal groove, 11 ... piston seal, 11a ... inner peripheral surface, 11b ... cylinder hole opening side surface, 11c ... corner portion, 12 ... dust seal

Claims (5)

A cylinder hole is provided in the working portion of the caliper body so as to open to the disk rotor side, a piston seal groove is provided in the cylinder hole, and a piston seal formed by a square seal is fitted into the piston seal groove. In a vehicle disc brake in which a piston is inserted into a cylinder hole via a seal,
The piston seal groove includes a cylinder hole opening side wall, a cylinder hole bottom side wall, and a bottom wall connecting the cylinder hole bottom side wall and the cylinder hole opening side wall, and the bottom wall faces the cylinder hole opening side. A curved portion having a parabolic cross-sectional shape in which the depth of the groove gradually increases,
The piston seal in an initial state that is not thermally expanded includes at least a cylinder hole bottom side wall of the piston seal groove and the piston seal, a cylinder hole opening side of the bottom wall of the piston seal groove, and the piston seal. Is provided with a space that allows thermal expansion of the piston seal, and the bottom wall faces the cylinder hole bottom side of the curved portion, and the cross-sectional shape is parallel to the cylinder axis or toward the cylinder hole bottom side. vehicle disc brake, characterized that you have provided a straight portion depth becomes gradually deeper in the piston seal groove Te. A cylinder hole is provided in the working portion of the caliper body so as to open to the disk rotor side, a piston seal groove is provided in the cylinder hole, and a piston seal formed by a square seal is fitted into the piston seal groove. In a vehicle disc brake in which a piston is inserted into a cylinder hole via a seal,
The piston seal groove includes a cylinder hole opening side wall, a cylinder hole bottom side wall, and a bottom wall connecting the cylinder hole bottom side wall and the cylinder hole opening side wall, and the bottom wall has an arc with a projecting cross section. A curved portion having a shape or a shape in which a plurality of projecting arcs having different curvatures are continuous, the depth of the groove gradually becoming deeper toward the cylinder hole opening side,
The piston seal in an initial state that is not thermally expanded includes at least a cylinder hole bottom side wall of the piston seal groove and the piston seal, a cylinder hole opening side of the bottom wall of the piston seal groove, and the piston seal. A space for allowing thermal expansion of the piston seal is provided in between.   The vehicular disc brake according to claim 2, wherein the plurality of projecting arcs having different curvatures have smaller curvatures as the arc arranged on the cylinder hole opening side. The bottom wall is provided with a linear portion on the cylinder hole bottom side of the curved portion, the cross-sectional shape of which is parallel to the cylinder axis or the depth of the piston seal groove gradually increases toward the cylinder hole bottom side. The vehicle disc brake according to claim 2 or 3 , characterized by the above-mentioned. The bottom wall, the cylinder bore bottom portion side of the bending portion, according to claim 2 or, characterized in that it comprises a bottom side curved portion depth of the piston seal groove becomes gradually deeper toward the cylinder bore bottom side 3. The disc brake for vehicles according to 3 .

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