JPH0210344Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention is a disc brake of an actuator opposed type disc brake that improves the effect of preventing so-called dragging noise caused by the friction material coming into contact with the disc during non-braking. Regarding.

[Conventional technology and its problems]

In the so-called actuator-opposed type disc brake, in which friction materials arranged facing each other around the disc are individually pressed by a pair of actuators to slide into contact with the disc, the amount of retraction of the actuator in one caliper is reduced for convenience in manufacturing. Everything is the same. For example, in a piston-opposed disc brake that has cylinders on both sides of the disc, the piston pullback when the brake is released is controlled by the third
As shown in the figure, a piston seal 3 is fitted into an annular piston seal groove 2 provided on the inner surface of a cylinder 1, and the inner surface of this seal is brought into pressure contact with the outer circumference of a piston 4 so as to generate an appropriate amount of frictional resistance during braking. The seal 3 is elastically deformed as shown by the chain line by the hydraulic pressure acting on one end surface and the movement of the piston, and when the brake is released, the restoring elasticity of the seal pulls the piston 4 back to its original position as shown by the solid line. . but,
The shapes and dimensions of the grooves 2 and the seals 3 are all the same if manufacturing variations are ignored, and therefore the return amount l of the piston is also the same.

By the way, one of the so-called brake squeals is,
There is a dragging sound of the friction material when not braking, and this sound is particularly likely to occur when the disk deforms due to thermal history and falls to one side, approaching one piston. Current preventive measures have the following drawbacks, and more effective means are needed.

In other words, there are currently two ways to counter drag noise: one is to forcibly separate the friction material using a wire spring that straddles the disk, and the other is to increase the absolute value of the return amount of the piston, but both methods reduce the drag noise. On the other hand, the total amount of brake fluid (required amount of fluid) supplied from a hydraulic pressure generating source such as a master cylinder for brake operation increases, which adversely affects pedal feel and the like. Furthermore, wire springs also have the problem of increased costs due to the addition of parts.

[Means for solving problems]

In the present invention, in order to eliminate the above-mentioned problems, the amount of retraction by the retract mechanism of the pair of actuators is set to be large on the side where the disk approaches when the disk deforms due to thermal history and is cooled, and small on the side where the disk separates.

In other words, the disk deforms due to thermal history, and the direction in which it will fall is known from the shape of the disk (generally it will fall toward the inner side).Therefore, the amount of piston return in the direction of fall is increased, and the resulting increase in brake fluid amount is counteracted. If this is offset by reducing the piston return amount on the side, the dragging noise can be reliably prevented without increasing the amount of fluid required for the brake.

〔Example〕

FIG. 1 shows an embodiment of the present invention. This disc brake uses the above-mentioned piston seal to pull back the piston 4 used as an actuator. That is, the inner side of the caliper 5 that straddles the disk D (the side away from the wheel W)
Opposed cylinders 1 and 1' are formed on the outer side (the side approaching the wheel W), and pistons 4 and 4' that press the friction materials 6 and 6' are inserted therein.

In addition, the piston seal groove 2 on the inner surface of the cylinder,
Inserted into 2' are outer peripheral seals of each piston 4, 4' and piston seals 3, 3' for pulling back.
It is pressed against the outer circumferential surfaces of the pistons 4, 4' so as to generate appropriate frictional resistance. Each piston seal groove 2, 2' has _a chamfer width A ₁ , A ₂ on the opening side.
＞A ₂ .

That is, in a disc brake in which the piston is returned to its original position by a piston seal, the edge of the piston opening side of the piston seal groove is removed (chamfered) by adding an inclined surface 7 as shown in detail in FIG. The piston seal is elastically deformed in the forward direction of the piston, and the amount of return of the piston is determined by the installation width A of the surface 7 in the disk axial direction. Therefore, as shown in _{FIG .}
If A ₁ > A ₂ is established, the return amount of the piston is approximately proportional to the chamfer width, so that the inner piston 4, where the disk D approaches due to deformation due to thermal history, is smaller than the outer piston 4', where the disk moves away. can also be pulled back significantly.

Then, A ₁ > A ₂ , A ₁ +A ₂ ≦2A (A is the return amount of one piston in a conventional disc brake)
If set to , dragging noise can be effectively prevented without increasing the required liquid volume. The dimensional difference of A ₁ − _{A 2} is for a typical automobile disc brake.
It is effective if it is 0.05mm or more.

Here, the direction in which the disk D falls due to its thermal history is not necessarily toward the inner side. That is,
The direction of inclination is opposite to the bending direction of the mounting boss d of the disk, and if the mounting boss were bent in the opposite direction to that shown in the figure, the return amount of the piston would be set to be large on the outer side.

The present invention is applicable not only to a disc brake in which one piston is opposed to each other on both sides of the disc, but also to a disc brake in which two or more pistons are incorporated in a caliper on one side of the disc.

In addition, a brake in which the piston is pulled back using another retract mechanism, for example, as shown in FIG. 2, a guide shaft 8 is fixed to the axial center of the cylinder 1,
A coiling bushing 9 that provides an appropriate amount of frictional resistance is fitted onto this shaft, and a spring 12 is suspended between a bushing housing 10 whose one end is locked to the bushing 9 and a seat plate 11 fixed to the piston 4. Some brakes use restoring force to move the piston forward by t ₁ + α (α = amount of wear of the friction material during the previous braking) and then pull it back by t ₁ when the brake is removed, and the same concept can be applied to such brakes. The magnitude of the piston return amount in this case is adjusted by changing the set value of the gap _t1 created between the bush housing 10 and the seat plate 11 when braking is not applied.

〔effect〕

As described above, in the present invention, the amount of return by the retract mechanism of the opposing actuators is set to be large on the side where the disk approaches during cooling due to its deformation due to thermal history, and small on the side where it moves away, and when not braking, the amount of return is set to be large on the side where the disk approaches during cooling. Ensure sufficient clearance between the disc and the friction material on both the inner and outer sides,
Moreover, since the amount of fluid required for the brake is not increased, it is possible to effectively prevent dragging noise without adversely affecting other performance or cost.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an example of the disc brake of the present invention, Fig. 2 is a sectional view showing the main parts of another embodiment, and Fig. 3 is a piston seal installation of a conventional brake using the piston seal as a retracting means. FIG. 1, 1'...Cylinder, 2, 2'...Seal groove,
3, 3'... Piston seal, 4, 4'... Piston, 5... Caliper, 6, 6'... Friction material, 7,
7'... Inclined surface, 8... Guide shaft, 9... Coiling bush, 10... Bush housing, 1
1...Seat plate, 12...Spring.

Claims (1)

[Scope of utility model registration request] In a disc brake, in which friction materials arranged facing each other around the disc are individually pressed by a pair of actuators and slid into sliding contact with the disc, the amount of retraction by the retract mechanism of the pair of actuators is reduced by the disc deforming due to its thermal history and approaching when it cools down. An actuator-opposed disc brake that is large on the side and small on the side away from the actuator.