JPH0715291B2 - Front disc brake device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a front disc brake device mounted on a vehicle such as an automobile as a braking means, and more particularly to an improvement in a brake pad shape thereof.

(Prior Art) Conventionally, as a brake pad used in a disc brake device, for example, one described in Japanese Utility Model Publication No. 48-1109 is known.

In this conventional brake pad, cutout portions that are not in contact with the disc rotor are formed at both ends of the brake pad in order to prevent brake squeal.

That is, when the brake pad is thermally deformed by the heat generated during braking, the heat radiation in the central portion of the brake pad is smaller than that in the surrounding area. Is raised, and the frictional vibration is increased due to the local high surface pressure contact, and brake squeal occurs. Therefore, by forming cut-off portions at both ends of the brake pad, the swelling of both ends caused by thermal deformation is suppressed and local high surface pressure contact is prevented.

(Problems to be solved by the invention) However, in such a conventional device, although the brake squeal prevention can be achieved by the cut-off portions formed at both ends of the brake pad, the brake judder is prevented due to the following reasons. There is a problem in that it cannot be effectively prevented.

That is, a lift force is generated on the brake pad of the disc brake during braking, and the lift force causes sliding resistance and twisting in various parts of the caliper, which causes vibration of the vehicle body and steering called brake judder.

With regard to this brake judder, when cutouts are provided at both ends of the brake pad as in the conventional case, since the cutout includes a portion that contributes little to the reduction of the lifting force during braking, the effective contact area of the brake pad Although the reduction range of sliding resistance is small, the effective contact area becomes small and the predetermined braking torque is reduced by reducing the sliding resistance. Since it is not possible to secure it, the brake judder cannot be effectively prevented.

(Means for Solving Problems) The present invention has been made for the purpose of solving the above-mentioned conventional problems, and in order to achieve this object,
In the present invention, the disc rotor is provided on the wheel side,
In a front disc brake device in which a caliper is provided on the vehicle body side, and a brake pad for sandwiching both sides of the disc rotor is provided on the caliper, a contact area of an upper portion of a rotation inlet side of the brake pad with respect to a disc rotor is an upper portion of a rotation outlet side. The cut portion is formed only on the inlet side of the brake pad from the rotary inlet side end edge portion to the rotary inlet side upper edge portion so as to be smaller than the contact area.

(Operation) The force acting on the brake pad during braking will be described with reference to FIG. 5. The force acting on the small area S in the brake pad P is Δf, and when this Δf is decomposed in the x direction and the y direction,
The decomposed Δfy in the y direction becomes the force that acts on the brake pad P being lifted.

Where Δf = R · dθ · dr · p ′ · μ p ′: hydraulic pressure per unit area μ: friction coefficient of the brake pad, and Δfy is the rotation inlet side when the rotation direction of the disk rotor is the arrow A direction. In M, it works in the upward direction (the direction in which the brake pad P floats up), in the rotation outlet side N, it works in the downward direction (the direction in which the brake pad P sinks), and this Δfy
On the rotation inlet side M, the distance becomes larger as the distance R from the rotation center O of the disk rotor increases corresponding to the peripheral speed of the disk rotor.

Therefore, in the present invention, as corresponding to the above-described action, since the inclined cutout portion is formed only on the rotation inlet side where the lifting force during braking is largely reduced and the sliding resistance is large, the brake pad is formed. It is possible to suppress the lifting force of the brake pad that causes brake judder during braking, while ensuring the effective contact area.

Embodiments Embodiments of the present invention will be described in detail below with reference to the drawings.

First, the configuration will be described.

2 and 3 show the front disc brake device 1 of this embodiment, and in this embodiment, a one-piston floating caliper type is adopted.

Reference numeral 2 is a disc rotor, which has a wheel hub fixed thereto and rotates together with a wheel (not shown).

Reference numeral 3 denotes a caliper, and a body 6 is supported by a floating bracket 4 fixed to the vehicle body through a slide pin 5 so as to be slidable in the axial direction of the disc rotor 2, and a piston 8 is attached to a cylinder 7 formed in the body 6 by a disc 8. The disc rotor 2 is fitted so as to be slidable in the axial direction of the rotor 2.
The brake pads 9.9 that face each other with the brake pad 9 sandwiched therebetween have a structure in which one brake pad 9 is fixed to the tip surface of the piston 8 and the other brake pad 9 is fixed.

In addition, 10 is a dust boot, and 11 is a piston seal, which has a function of holding a hydraulic pressure and adjusting a gap between the brake pad 9 and the disc rotor 2.

As shown in FIG. 1, when the rotation direction of the disc rotor 2 is set to the direction of arrow A, the brake pad 9 has a contact area at the upper portion of the rotation inlet side M with respect to the disc rotor 2 that of the rotation outlet side N. A portion 92a extending over the entire edge of the rotation inlet side end edge portion 91 of the brake pad 9 and a portion 92b extending from the rotation inlet side end edge portion 91 to the rotation inlet side upper edge portion 93 so as to be smaller than the contact area of the upper portion. In the structure, an inclined cutout portion 92 (shown by diagonal lines in the drawing) is formed by chamfering.

The inclined cutout portion 92 may be cut as well as chamfered, and the processing method may be any of polishing, cutting, die molding and the like.

Further, instead of the inclined cutout portion 92, the inclined surface portion of FIG. 1 may be completely cut off.

Next, the operation will be described.

During braking, the brake fluid pressure generated based on the braking operation activates the piston 8 to press one brake pad 9 against one surface of the disc rotor 2, and the reaction force causes the body 6 to be guided by the slide pin 5. By sliding in the opposite direction, the other brake pad 9 is pressed against the other surface of the disc rotor 2. As a result, both sides of the disc rotor 2 are clamped by the brake pads 9.9 and a braking force is applied.

Then, at the time of this braking, the contact area of the upper portion of the rotation inlet side M becomes smaller than the contact area of the upper portion of the rotation outlet side N due to the inclined cutout portion 92 formed on the brake pad 9.
As described in the above section (action), the lifting force of the brake pad 9 is significantly reduced.

Further, since the inclined cutout portion 92 of the brake pad 9 also includes a portion 92a extending over the entire edge of the rotation inlet side end edge portion 91, this portion 92a does not come into contact with the disc rotor 2 and the heat of the brake pad 9 is lost. Swelling of the portion 92a due to deformation is suppressed.

In FIG. 4, the effective contact area and sliding resistance of the brake pad before cutting are 100%, and the brake pad 9 of this embodiment is
The experimental results comparing the relationship between the effective contact area and the sliding resistance in the case of using are shown with those in the case of using the conventional brake pad. In this figure, it can be seen that when the brake pad 9 of this embodiment is used, compared with the conventional brake pad, the sliding resistance can be greatly reduced while the reduction of the effective contact area is reduced.

Therefore, in this embodiment, the following effects are exhibited.

Since the inclined cutout portion 92 is formed only in the rotation inlet side where sliding resistance is large and the sliding resistance is large during braking, the effective contact area of the brake pad 9 is secured while the brake pad is being braked. It is possible to suppress the lifting force of 9 and prevent brake judder.

Since the inclined cutout portion 92 of the brake pad 9 also includes a portion 92a that extends over the entire edge of the rotation inlet side end edge portion 91, it is possible to prevent brake squeal due to local high surface pressure contact.

The embodiments of the present invention have been described above with reference to the drawings. However, the specific configuration of the present invention is not limited to the above-mentioned embodiments. For example, a fixed caliper type disc brake device or a two-piston floating caliper type disc brake device. Of course, the brake pad of the present invention can be applied.

Further, in the embodiment, the example of the inclined cutout portion 92 including the portion 92a extending over the entire edge of the rotation inlet side end edge portion 91 has been shown.
The present invention also includes an example in which the inclined cutout portion is not included.

(Effects of the Invention) As described above, according to the present invention, the entrance of the brake pad is adjusted so that the contact area of the upper part of the rotation inlet side of the brake pad with respect to the disc rotor is smaller than the contact area of the upper part of the rotation outlet side. Since the cut portion is formed only on the side from the rotary inlet side end edge portion to the rotary inlet side upper edge portion, without increasing the processing accuracy and the number of parts that increase cost,
Moreover, the effect that the brake judder caused by the lifting force generated in the brake pad can be prevented while securing the effective contact area of the brake pad with the disc rotor is obtained.

[Brief description of drawings]

1 is a front view of a brake pad in a front disc brake device according to an embodiment of the present invention, FIG. 2 is a plan view of the embodiment device, FIG. 3 is a partial cross-sectional view of the embodiment device, and FIG.
FIG. 5 is an experimental result diagram comparing the relationship between the effective contact area and the sliding resistance between the case of using the brake pad of this embodiment and the case of using the conventional brake pad, and FIG. 5 is a diagram for explaining the operation. DESCRIPTION OF SYMBOLS 1 ... Front disc brake device 2 ... Disc rotor 3 ... Caliper 9 ... Brake pad 91 ... Rotation inlet side edge 92 ... Inclined cut portion 93 ... Rotation inlet side upper edge M ... Rotation inlet side N ... Rotation outlet side

Claims (1)

[Claims] 1. A disk rotor is provided on the wheel side,
In a front disc brake device in which a caliper is provided on a vehicle body side, and a brake pad for sandwiching both sides of the disc rotor is provided on the caliper, a contact area of an upper portion of a rotation inlet side of the brake pad with respect to a disc rotor is an upper portion of a rotation outlet side. The front disc brake device is characterized in that a cut portion is formed only on the inlet side of the brake pad from the rotary inlet side end edge portion to the rotary inlet side upper edge portion so as to be smaller than the contact area of the brake pad.