JPH0714671Y2 - Disc brake caliper - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a disc brake caliper that reduces drag torque generated by friction pads slidingly contacting a disc when not braking without increasing piston stroke during braking. .

[Conventional technology]

Among known disc brake calipers, there is a disc brake caliper that also uses a liquid ring on the outer periphery of the brake piston to pull back the brake piston from the pressurizing point of the friction pad by a certain amount during depressurization.

This is shown in FIG. 3, and as shown in the figure, a rubber ring 4 is held in an annular groove 3 on the inner surface of the cylinder 2, and this rubber ring is fitted around the brake piston 5 with a tight margin. Further, a chamfered portion 6 for removing the groove edge is provided on the side opposite to the liquid sealing side of the annular groove 3.

When the brake caliper 1 is pressed, the piston 5 drags the rubber ring 4 to the position where the chamfered portion 6 regulates the rubber ring 4 to elastically deform it as shown in FIG. When the piston stroke exceeds δ, the amount of elastic deformation at this time is always constant because slip occurs between the piston and the rubber ring in accordance with the excess amount. Therefore, when depressurizing, the elastic restoring force of the rubber ring 4 is used. The piston 5 is always pulled back by a fixed amount (approximately δ).

Conventionally, the chamfering amount δ that regulates the deformation amount of the rubber ring is set to the same value over the entire circumference.

[Problems to be solved by the device]

As shown in FIG. 5, the disc brake caliper presses the pair of friction pads 11, 11 on the disc inner peripheral side of the bridge portion 1a across the disc 10, and therefore, as shown by the chain line in the figure when hydraulically loaded. (The figure is exaggerated for ease of understanding).

However, especially when the degree of freedom of inclination is intentionally given to the piston in order to prevent the uneven wear of the pad due to the deformation of the caliper, the piston 5 is not straight when trying to be in close contact with the back plate of the pad. Holds the posture and, for this reason,
The piston protrusion amount from the cylinder and the piston slip amount with respect to the rubber ring become large on the inner peripheral side of the disc. On the other hand, according to the conventional structure, the piston return amount at the time of depressurization is constant over the entire circumference, and therefore, the piston after depressurization remains tilted with respect to the cylinder axis as shown in FIG.

In order to reduce the drag torque in the state of FIG. 6, the gap between the pad and the piston must be set so that the minimum clearance a part has a value required in design. However, the actual value of the clearance in this case is ab
However, since the difference between b and a becomes the ineffective piston stroke during braking, the amount of liquid consumption increases, and the responsiveness of the brake and the pedal feel deteriorate.

[Means for Solving the Problems]

This invention, as a means for solving the above problems,
The chamfering amount of the chamfered portion of the groove on the anti-liquid-sealing side of the annular groove is small on the outer peripheral side of the disc and large on the inner peripheral side. Adopt a configuration that is approximately equal to the difference in the amount of axial deformation.

[Action]

The return amount of the piston is proportional to the anti-liquid sealing side chamfering amount of the annular groove. Therefore, according to the present invention, the piston return amount becomes large on the inner peripheral side of the disc during depressurization and the piston protrusion amount during pressurization. And the piston is parallel to the cylinder axis during non-braking, and the clearance between the piston and the pad is substantially equal over the entire front surface of the piston.

〔Example〕

 1 and 2 show an embodiment of this invention.

As shown in the figure, the brake piston 5 is inserted into the cylinder 2 with a slight clearance so as to have a degree of freedom of inclination within a required range, and between the piston 5 and the cylinder 2 is a rubber ring 4 as in the conventional case. It is liquid sealed by.

The chamfered portion 6 on the anti-liquid-sealing side of the annular groove 3 which holds the rubber ring 4 has a chamfered amount of A on the inner peripheral side of the disk 10 and B (<A) on the outer peripheral side from the inner peripheral side to the outer peripheral side. It has been reduced towards.

In the figure, X and Y are the amount of axial displacement of the caliper 1 in the disc radial direction piston position of the caliper 1 due to normal hydraulic pressure, and the above numerical values A and B are such that the difference is substantially equal to the difference between X and Y. In other words, that is, the value is set to satisfy the equation of AB≈XY.

Therefore, when not braking, the friction pad 11 and the brake piston 5
When the clearance generated between and is Δl, A is X + Δl and B is Y + Δl.

In the brake caliper of this example, B + α (α is the amount of pad wear) on the disk outer peripheral side of the piston 5 and A + α advances on the disk inner peripheral side during braking. At this time, with respect to α, a slip occurs between the rubber ring and the rubber ring.
Since the calipers are respectively restored to X and Y, the clearance between the caliper and the pad after depressurization is Δl over the entire front surface of the piston.

〔effect〕

As described above, according to the present invention, the pistons after depressurization are performed by making a difference in the chamfering amount of the anti-liquid sealing side chamfer of the annular groove that determines the piston return amount on the inner and outer peripheral sides of the disc. Is maintained parallel to the cylinder axis, the drag torque can be reduced without unnecessarily increasing the piston stroke that affects responsiveness and pedal feeling.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention in a use state, FIG. 2 is a front view showing a positional relationship between a cylinder and a chamfered portion, and FIG. 3 is a main part of a brake caliper to be improved. 4 is a partial sectional view showing the elastically deformed state of the rubber ring, FIG. 5 is a diagram showing the deformed state of the caliper during braking, and FIG. 6 is a diagram showing the caliper of FIG. 5 after decompression. It is a diagram showing a state. 1 ... Caliper, 1a ... Bridge part, 2 ... Cylinder,
3 ... annular groove, 4 ... rubber ring, 5 ... brake piston, 6 ... chamfer, 10 ... disk, 11 ... friction pad.

Claims (1)

[Scope of utility model registration request] 1. A rubber ring held on the inner circumference of an annular groove on the inner surface of the cylinder is brought into close contact with the outer circumference of a brake piston incorporated in the cylinder with a tightening margin, and the rubber ring seals liquid between the brake piston and the cylinder, and In the disc brake caliper that pulls back the brake piston by a predetermined amount when decompressed by the elastic restoring force of this rubber ring that is elastically deformed by being dragged by the piston at the time of pressurization, the opposite of the annular groove that regulates the elastic deformation amount of the rubber ring when pressed The chamfering amount of the liquid seal side groove edge chamfer is small on the outer peripheral side of the disc and large on the inner peripheral side,
Further, the disc brake caliper is characterized in that the difference in chamfer amount is made substantially equal to the difference in the disc axial direction deformation amount due to the normal hydraulic pressure of the caliper at the disc radial direction piston position.