JPH11280805A - Disc brake - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disc brake which can surely return a piston to its original position. SOLUTION: A surface of a side wall part 9a on the side remote from the liquid pressure side, is constituted by several curved surfaces having curvatures which continuously vary from the bottom part to the opening part of an annular groove 9 as viewed in a sectional view. When brake fluid is fed into a liquid pressure chamber 5 so as to advance a piston 3, a seal member 10 is deformed along the side wall surface part 9a on the side remote from the liquid pressure side, in its entirety including its outer peripheral side part. Thus, shearing deformation energy caused by the deformation is accumulated in the interior part of the seal member in its entirety, and discharge of shearing deformation energy due to a slip from being minimumly restrained without causing a slip between the outer peripheral wall of the piston and the contact part of the seal member. Further, a substantial part of restoring force due to elastic deformation of the seal member 10 becomes larger, thereby making it possible to surely pull back the piston 3 to its original position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disc brake provided on an automobile.

[0002]

2. Description of the Related Art As an example of a conventional disc brake,
There is one shown in FIG. In FIG. 7, a caliper 2 is supported on a carrier 1 provided on a fixed portion (not shown) of the automobile so as to be movable in the left-right direction in FIG. The caliper 2 is formed with a cylinder 4 for slidably storing the piston 3.

When the brake fluid is supplied to the hydraulic chamber 5 between the bottom of the cylinder 4 and the piston 3, the piston 3 moves forward (moves leftward in FIG. 7) and the inner pad 6 moves.
a to the brake rotor 7, and the reaction causes the caliper 2 to move rightward in FIG. 7, and the claw 8 of the caliper 2 presses the outer pad 6b against the brake rotor 7, thereby generating a braking force. I have. An annular groove 9 is formed on the inner wall of the cylinder 4. A ring-shaped seal member 10 for sealing the space between the cylinder 4 and the piston 3 with liquid is fitted in the annular groove 9. A chamfer 11 is provided at the edge of the annular groove 9 on the side opposite to the hydraulic pressure (the wall surface on the left side in FIG. 7).

[0004] In this disc brake, when the brake fluid is supplied to the fluid pressure chamber 5, the seal member 10 is dragged by the piston 3 as shown in FIG.
The annular groove 9 is elastically deformed so as to escape to an escape space T formed by a chamfer 11 provided on the anti-hydraulic side wall surface portion 9a (the wall surface portion on the left side in FIG. 8). When the pressure is released, as shown in FIG. 9, the piston 3 is pulled back toward the original position (to the right in FIG. 9) by the restoring force based on the elastic deformation of the seal member 10.

[0005] In this disc brake, a chamfer 11 is provided on the anti-hydraulic side wall surface portion 9a.
8 and 9, a break point 9b (which is an annular line as a whole) is formed, and the anti-hydraulic side wall surface portion 9 is formed.
a is chamfered 11 and seal member 10
Supports (restrains) the outer peripheral side (bottom side of annular groove 9)
And the anti-hydraulic side wall surface main body 9c. During pressurization when the brake fluid is supplied to the hydraulic chamber 5, a portion on the inner peripheral side of the portion corresponding to the break point 9 b in the seal member 10 when the seal member 10 is assembled (the open side portion of the annular groove 9). ) Is dragged by the piston 3 and deformed.

[0006]

However, in the above-described prior art, since the portion where the seal member 10 is deformed is limited to the inner peripheral side portion as described above, the region where the hydraulic pressure is large (high fluid In the pressure region), when the shear strain energy due to the seal deformation cannot be stored in the inner peripheral portion of the seal member 10, the seal member 10 may slip against the outer peripheral wall of the piston 3 and release the shear strain energy. It can happen. For this reason, the elastic restoring force of the seal member 10 required to return the piston 3 to the original position at the time of depressurization becomes insufficient, and in some cases, the restoring force on the piston 3 becomes insufficient, and the piston 3 cannot be returned to the original position. Nothing could happen.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a disc brake capable of surely returning a piston to an original position.

[0008]

According to the first aspect of the present invention,
An annular groove is formed in an inner wall of a cylinder of a caliper that houses a piston, and a ring-shaped sealing member that seals liquid between the cylinder and the piston is fitted in the annular groove, and the seal generated when the piston is pressurized. In a disc brake having a piston return mechanism that pulls back the piston at the time of decompression by a restoring force based on elastic deformation of the member, the anti-hydraulic side wall surface portion of the annular groove has a piston side opening inclined in the direction of hydraulic pressure action. It is characterized by being.

According to a second aspect of the present invention, in the configuration of the first aspect, the inclination of the wall surface of the anti-hydraulic side wall portion of the annular groove changes continuously from the bottom to the opening of the annular groove. It is characterized by comprising a group of curved surfaces.

[0010] The third aspect of the present invention is the first or second aspect.
Wherein a ring member having a hardness smaller than that of the seal member is interposed between the anti-hydraulic side wall surface portion of the annular groove and the seal member.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. The illustration and description of the parts and members equivalent to those shown in FIGS. 7 to 9 and members are appropriately omitted. 1 and 2,
The wall surface of the anti-hydraulic side wall surface portion 9a (the wall surface portion on the left side in FIG. 1) in the annular groove 9 has a substantially arc shape that is outwardly convex when viewed in cross section [ie, the anti-hydraulic side wall surface portion of the annular groove 9]. 9a is
The piston-side opening is inclined in the direction in which the hydraulic pressure is applied (leftward in FIG. 1). In this case, the anti-hydraulic side wall surface portion 9a is configured as follows, and the wall surface is formed of a group of curved surfaces whose curvature changes continuously in cross section from the bottom to the opening of the annular groove 9 [see FIG. The inclination of the wall surface of the anti-hydraulic side wall surface portion 9a of the annular groove 9 is a group of curved surfaces whose curvature continuously changes from the bottom to the opening of the annular groove 9].

The anti-hydraulic side wall surface portion 9a will be described below. In the cross-sectional view of FIG. 2, a point A (which forms an annular line as a whole) is a portion where the anti-hydraulic side wall surface portion 9a and the bottom of the annular groove 9 intersect, and when the seal member 10 is assembled. It corresponds to a sealing portion at the bottom of the annular groove 9. C
Is an imaginary point indicating a portion where a perpendicular drawn from the point A to the outer peripheral wall of the piston 3 intersects the outer peripheral wall in the cross-sectional view of FIG. S indicates the stroke of the piston 3. Point B
Is an imaginary point indicating a portion separated by a stroke S from the point C on the outer peripheral wall of the assembled piston 3 when the seal member 10 is assembled.

Here, when the axial direction of the piston 3 is the direction of the Z coordinate axis and the radial direction of the piston 3 is the r coordinate axis,
The curved surface at the point A or the point B of the anti-hydraulic side wall surface portion 9a is represented by F
The shape is represented by a functional of (r, Z) = 0.
At this time, the curved surface at the point A or the point B of the anti-hydraulic side wall surface portion 9a is as shown by the following equation (1) [tangential condition] near the point A, and the following equation (2) near the point B. [Tangent condition], and point A (bottom of annular groove 9)
Until the point B (the opening side portion of the annular groove 9), the curved surface group whose curvature continuously changes is configured.

[0014]

(Equation 1)

[0015]

(Equation 2)

The length (depth of the annular groove 9) L from the bottom (corresponding to point A) of the anti-hydraulic side wall surface portion 9a to the opening (corresponding to point C) is larger than the stroke S. It is set to a large (L> S) dimension.

In the disk brake constructed as described above, the brake fluid is supplied to the hydraulic chamber 5 and the piston 3
Moves forward (moves leftward in FIG. 1) when the sealing member 1
The seal member 10 is deformed in a direction to fill the space K formed between the first hydraulic fluid 0 and the anti-hydraulic side wall surface portion 9a, and this deformation is caused during the movement of the piston 3 by the stroke S (that is, the stroke S of the piston 3). Over the range).

In the present embodiment, the wall surface of the anti-hydraulic side wall surface portion 9a is constituted by a group of curved surfaces whose curvature changes continuously in cross section from the bottom to the opening of the annular groove 9. Therefore, when the brake fluid is supplied to the hydraulic chamber 5 and the piston 3 moves forward (moves to the left in FIG. 1), the seal member 10 moves to the anti-hydraulic side wall surface portion 9a regardless of the level of the hydraulic pressure. As a result, the seal member 10 is deformed over the entire portion including the outer peripheral portion. For this reason, it is possible to store the shear strain energy due to the deformation in the entirety of the inside of the seal member 10, and the “slip operation generated between the outer peripheral wall of the piston 3 and the contact portion of the seal member, which may be caused by the related art. Is suppressed, the release of the shear strain energy due to the slip can be minimized, and the restoring force based on the elastic deformation of the seal member 10 increases accordingly, and the piston 3 is moved to the original position. Can be surely pulled back.

Further, since the piston 3 can be reliably returned to the original position, the life of the inner pad 6a and the outer pad 6b (see FIG. 7) can be extended, and the brake rotor 7 (see FIG. 7). Can be improved. Further, in the conventional technology in which the shear strain energy is released at the time of a high load, the return stroke is insufficient at the time of a high load, and the piston stroke increases at the time of a low load. However, in the present embodiment, the piston 3 can be reliably returned to the original position as described above, so that the problems of the related art can be improved.

In the above-described embodiment, the case where the chamfered portion is not provided on the bottom side portion of the anti-hydraulic side wall surface portion 9a has been described as an example. Alternatively, as shown in FIG. A chamfered portion 20 in which the radial dimension n is set to be extremely smaller than the depth dimension L of the annular groove 9 may be provided on the bottom side portion of the portion 9a. In this case, the anti-hydraulic side wall surface portion 9a
Moiety A ₁ to the point B which intersects the chamfered portion 20 in the
Up to the (opening side portion of the annular groove), it is composed of a curved surface group whose curvature continuously changes. The one shown in FIG.
The diameter of the annular groove 9 is made larger as it is closer to the hydraulic pressure side, so that the bottom of the annular groove 9 does not coincide with the axial direction.

Further, as shown in FIG. 4, the depth dimension of the annular groove 9 is shorter than that of the embodiment shown in FIGS. The auxiliary annular groove 9H is additionally formed, and the auxiliary annular groove 9H (including the annular groove 9) is formed.
Alternatively, the seal member 10 may be fitted with an interference. In FIG. 4, E and F are points respectively indicating the corner of the anti-hydraulic side portion and the corner of the hydraulic side portion at the bottom of the auxiliary annular groove 9H. In the disc brake shown in FIG. 4, the portion of the anti-hydraulic side wall surface portion 9a between the points A and B is constituted by a group of curved surfaces whose curvature continuously changes.

In this disk brake, since the wall surface of the anti-hydraulic side wall surface portion 9a is constituted by a group of curved surfaces whose curvature continuously changes in cross section from point A to point B, the hydraulic pressure chamber is formed. 5 (see FIG. 1), when the brake fluid is supplied and the piston 3 moves forward (moves to the left in FIG. 4), the seal member 10 moves along the anti-hydraulic side wall surface portion 9a regardless of the level of the hydraulic pressure. While being deformed, the seal member 10 is deformed over the whole including the outer peripheral portion. For this reason, it is possible to store the entire shear strain energy due to the deformation inside the seal member 10, and it is possible to suppress the occurrence of a sliding operation between the outer peripheral wall of the piston 3 and the contact portion of the seal member, thereby suppressing the shearing due to the slip. The release of strain energy can be minimized, and the restoring force based on the elastic deformation of the seal member 10 increases accordingly,
The piston 3 can be reliably returned to the original position.

Next, a second embodiment of the present invention will be described with reference to FIG. In FIG. 5, the anti-hydraulic side wall surface portion 9a
A plurality of auxiliary annular grooves 9J whose diameter decreases from the hydraulic side to the anti-hydraulic side are continuously formed, and have a step-like shape in cross section. In this case, the virtual plane formed by the envelope 30 of the plurality of auxiliary annular grooves 9J is the point A
And a curved surface group whose curvature continuously changes in cross section from point B to point B.

In this disk brake, the virtual surface formed by the envelope 30 of the plurality of auxiliary annular grooves 9J is constituted by a group of curved surfaces whose curvature changes continuously in cross section from point A to point B. Therefore, when the brake fluid is supplied to the hydraulic chamber 5 (see FIG. 1) and the piston 3 moves forward (moves to the left in FIG. 5), the seal member 10 is moved regardless of the level of the hydraulic pressure. The seal member 10 is deformed along the anti-hydraulic side wall surface portion 9a including the imaginary surface formed by the envelope 30, and the seal member 10 is deformed substantially entirely including the outer peripheral portion. For this reason, it becomes possible to store the shearing strain energy due to the deformation in the entirety of the inside of the seal member 10, and it is possible to suppress the occurrence of a sliding operation between the outer peripheral wall of the piston 3 and the contact portion of the seal member 10. The release of the shear strain energy can be minimized, and the restoring force based on the elastic deformation of the seal member 10 increases accordingly, and the piston 3 can be reliably returned to the original position. In the second embodiment,
The anti-hydraulic side wall surface portion 9a is not formed in a curved surface shape,
The annular groove 9 including the plurality of auxiliary annular grooves 9J can be easily formed.

Next, a third embodiment of the present invention will be described with reference to FIG. The third embodiment is different from the first embodiment shown in FIGS. 1 and 2 in that a ring member having a smaller hardness than the seal member 10 is provided between the anti-hydraulic side wall surface portion 9a and the seal member 10. It is different that 40 was interposed. In this case, a clearance space 41 is formed between the seal member 10 and the ring member 40, and a clearance space 42 is formed between the anti-hydraulic side wall surface portion 9 a and the ring member 40.

According to the third embodiment, the hydraulic chamber 5
When the brake fluid is supplied to the piston 3 and the piston 3 moves forward (moves to the left in FIG. 6), the seal member 10
Deforms to enter 1. Further, since the wall surface of the anti-hydraulic side wall surface portion 9a is formed of a group of curved surfaces whose curvature continuously changes from the bottom to the opening of the annular groove 9, the hydraulic pressure is further reduced. By acting, the seal member 10 is deformed along the anti-hydraulic side wall surface portion 9a via the ring member 40 so that the ring member 40 and the seal member 10 fill the clearance space 42, and the seal member 10 is Deformation over the whole including.

For this reason, it is possible to store the shear strain energy due to the deformation in the entirety of the inside of the seal member 10, which may occur between the outer peripheral wall of the piston and the contact portion of the seal member, which may be caused by the prior art. The occurrence of "slip operation" is suppressed, and the release of shear strain energy due to the slip can be minimized. As a result, the restoring force based on the elastic deformation of the seal member 10 increases accordingly, and the Can be surely pulled back to the position. In the third embodiment, since the ring member 40 having a hardness smaller than that of the seal member 10 is interposed between the anti-hydraulic side wall surface portion 9a and the seal member 10,
It is possible to make 0 store a part of the restoring force, and accordingly, the degree of freedom in design is increased.

[0028]

According to the first aspect of the present invention, since the piston-side opening of the anti-hydraulic side wall portion of the annular groove is inclined in the direction in which the hydraulic pressure acts, when the piston advances during pressurization, the hydraulic pressure decreases. Regardless of the height, the seal member is easily deformed along the anti-hydraulic side wall surface portion, and is deformed entirely including the outer peripheral portion thereof. For this reason, it becomes possible to store the shear strain energy due to the deformation in the entirety of the seal member, and the “sliding operation that occurs between the outer peripheral wall of the piston and the contact portion of the seal member”, which may be caused by the conventional technology, is achieved. The release of the shear strain energy due to the slippage can be minimized, and the restoring force based on the elastic deformation of the seal member increases accordingly, and the piston is reliably returned to the original position. be able to. By being able to pull the piston back to its original position,
The life of the pad can be extended, and the sound and vibration performance of the brake rotor can be improved. Further, in the conventional technology in which the shear strain energy is released at a high load, the return stroke is insufficient at a high load, and the piston stroke increases at a low load, resulting in an increase in brake operability. However, in the present invention, since the piston can be reliably returned to the original position as described above, it is possible to improve the problems of the related art.

According to the second aspect of the present invention, the inclination of the wall surface of the anti-hydraulic side wall portion of the annular groove is constituted by a group of curved surfaces whose curvature continuously changes from the bottom to the opening of the annular groove. Sometimes, regardless of the level of the hydraulic pressure, the sealing member easily deforms along the anti-hydraulic side wall surface, including the outer peripheral portion, so that the shear strain energy due to the deformation is stored and restored throughout the sealing member. The force can be set to a sufficiently large value, and the piston can be reliably returned to its original position.

According to the third aspect of the present invention, the ring member having a hardness smaller than that of the seal member is interposed between the anti-hydraulic side wall surface of the annular groove and the seal member. It is possible to store the parts, and accordingly, the degree of design freedom is high.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of the present invention.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a cross-sectional view showing an example in which a chamfered portion is provided on the bottom side of the anti-hydraulic side wall surface portion.

FIG. 4 is a sectional view showing an example in which an auxiliary annular groove is provided.

FIG. 5 is a sectional view showing a second embodiment of the present invention.

FIG. 6 is a sectional view showing a third embodiment of the present invention.

FIG. 7 is a sectional view showing an example of a conventional disk brake.

8 is a cross-sectional view showing a state when the disc brake of FIG. 7 is pressurized.

FIG. 9 is a cross-sectional view showing a state at the time of depressurization of the disc brake of FIG. 7;

[Explanation of symbols]

 2 Caliper 3 Piston 4 Cylinder 9 Annular groove 9a Anti-hydraulic side wall surface 10 Seal member

Claims (3)

[Claims] An annular groove is formed in the inner wall of a cylinder of a caliper for accommodating a piston, and a ring-shaped sealing member for sealing liquid between the cylinder and the piston is fitted in the annular groove. In a disc brake having a piston return mechanism for retracting the piston at the time of depressurization by a restoring force based on elastic deformation of the seal member generated at the time of pressurization, the piston-side opening of the annular groove has a counter-hydraulic side wall surface that acts on the hydraulic side. Disc brake characterized by being inclined in the direction. 2. The slope of the wall surface of the anti-hydraulic side wall portion of the annular groove is formed by a group of curved surfaces whose curvature continuously changes from the bottom to the opening of the annular groove. Disc brake. 3. The disc brake according to claim 1, wherein a ring member having a hardness smaller than that of the seal member is interposed between the anti-hydraulic side wall surface portion of the annular groove and the seal member. .