JPH0159461B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a disc brake pad that is incorporated into a disc brake used for braking an automobile and performs braking by pressing a lining from both sides against a rotor that rotates together with the wheel. In particular, this invention relates to improvements to pads attached to disc brakes equipped with parking brake mechanisms.

(Prior Art) A disc brake is a brake that performs braking by pressing a pad lining against the side surface of a rotor that rotates together with a wheel, using a piston fitted into a cylinder and pushed out by hydraulic pressure.

Piston 1 that pushes the pad toward the rotor
As shown in Fig. 1, a hollow cylindrical piece with one end closed in the shape of a tip was used, and the open end of the tip was brought into contact with the back metal of the pad. Therefore, the piston 1 and the back metal 3 of the pad 2 were in contact only in a narrow annular area of the open end surface of the piston.

However, in recent years, as the number of automobiles equipped with disc brakes on all wheels has increased, a parking brake mechanism is often attached to the disc brake.

(Problem to be Solved by the Invention) The piston of a disc brake is formed hollow in the shape of a hollow tip in order to reduce its weight.In a disc brake without a parking brake mechanism, the open end of the hollow tip is formed as shown in Figure 1. It is in contact with the backing metal in a small area towards the backing metal of the pad.

However, in disc brakes equipped with a parking brake mechanism, as shown in Japanese Patent Laid-Open No. 53-146073, the parking brake mechanism is installed inside a hollow piston, so the operation of the parking brake mechanism is difficult. This must be done from the open end of the piston. Therefore, the end face of the piston, which has a wide area and corresponds to the bottom of the tip, comes into contact with the back metal of the pad. The disc brake shown in the above publication has an auto-adjustment mechanism that automatically adjusts the wear of the lining inside the piston in conjunction with the parking brake mechanism. Even if a parking brake mechanism is not provided, if a parking brake mechanism is installed inside the piston, the small opening end surface cannot be brought into contact with the pad, and a large area corresponding to the bottom of the stopper is used to hold the piston against the backing of the pad. It will have to come into contact with the For this reason, most of the heat generated by friction between the rotor 4 and the pad lining 5 during braking is transmitted to the piston 1 via the back metal 3, raising the temperature of the pressure oil in the cylinder 6. A temperature rise in the pressure oil is undesirable because if it becomes significant, vapor lock will occur and the braking force will be reduced.

Even when the present invention is attached to a disc brake that is equipped with a parking brake mechanism so that the bottom part of the hollow piston comes into contact with the backing metal, the contact area between the backing metal and the piston can be reduced, and the piston It is an object of the present invention to provide a disc brake pad that can suppress the rise in oil temperature in a cylinder fitted with a disc brake pad.

(Means for Solving the Problems) This invention forms a linear groove-like recess on the surface of the back metal of the pad facing the piston, which contacts the piston end surface only at two partial circles of small area on both side edges. At the same time, the above-mentioned problem is solved by making the side of the back metal opposite to the recess bulge into a linear protrusion along with the formation of the recess.

(Function) Since the piston only contacts the two side edges of the linear groove-shaped recess formed in the backing plate at two partial circles with a small area, even if the piston is used with its wide end face facing the backing metal of the pad, the backing metal will not touch the backing metal. Heat transfer from the piston to the piston can be reduced.

In addition, a bulge is formed on the surface of the back metal opposite to this concave part along with the formation of the linear groove-like recess, and since the lining is attached to the back metal to cover this, the lining is parallel to the back metal during braking. Even if a force in the shearing direction is applied, there is less risk of the lining peeling off from the backing metal.

In addition, a disc brake pad in which cooling fins are formed on the back metal of the pad, and the piston and the back metal contact each other through a large number of protrusions, was developed in the 1970s.
Although described in Japanese Patent No. 58181, this structure inevitably creates a slight difference in the height of the protrusions. If you press the backing metal of this pad with a piston end face with a large area such as the bottom of a brake pad, the piston will come into contact with these multiple protrusions, making the piston's ability to hold the pad unstable, causing vibrations and noise during braking. There is a risk of This pad is different from the pad of the present invention, which has the effect of ensuring that the pad is held down by the piston.

(Example) FIG. 2 shows an example of the present invention. Secret money 7
In the pad 9 formed by pasting the lining 8 on the back metal, a straight groove-shaped recess 10 is formed in the center of the surface of the back metal facing the piston in the width direction of the back metal. A bulge 11 is formed on the side surface in a shape corresponding to the recess 10. The width W of the recess 10 is smaller than the outer diameter of the piston 1, and the piston 1 comes into contact with the back metal 7 only at two small-area partial circles a and a on both side edges of the recess 10. The amount of protrusion 1 of the bulging portion 11 is set to be less than the maximum allowable wear thickness of the lining 8 to prevent the back metal 7 from coming into contact with the rotor side surface and damaging the rotor when the lining is worn.

Since it is configured as described above, even if the back metal of the pad is pushed by the end surface of the piston with a wide area,
This piston comes into contact with the backing metal of the pad only in a narrow area of the end surface, and air is interposed between the other end surface portions and the backing metal 7 to prevent heat transfer between the two.
When this air flows, it cools the back metal, making it difficult for the heat generated during braking to be transferred to the piston, and the increase in oil pressure inside the cylinder is minimal. Therefore, it is possible to prevent a decrease in braking force due to a rise in oil temperature in vapor locks, etc., and to obtain stable braking at all times, thereby improving safety.

To form such a straight groove-like recess in the backing metal, a steel plate having the thickness of the backing metal is usually pressed to form the straight groove. When forming a linear protrusion on the back surface of the backing metal, the opposite side of the backing metal tends to protrude in a linear protrusion, so forming a linear protrusion on the back surface of the backing metal at the same time as forming a linear groove-like recess is a problem in that only the recess is formed. Compared to the case where the back metal is formed, the flow of the back metal becomes natural and it is easier to form, and since the lining is attached to the back metal to cover this bulge, the lining is sheared in the direction of shearing during braking due to the engagement between the back metal and the lining. The bond between the lining and the back metal remains strong even when a force of

Further, since the piston and the back metal contact each other only at the two small-area partial circles a and a, the back metal can be held down stably by the piston, and no noise is generated due to vibration of the pad during braking.

In the illustrated embodiment, the recess 10 is formed in the width direction of the back plate 7, but the heat transfer blocking effect can be achieved even in directions other than the width direction in which the linear groove-shaped recess 10 is formed. can get. Generally speaking, it may be in the radial direction of the piston.

(Effects of the invention) (1) Since the piston and the back metal contact each other only at the small-area partial circles a and a on both sides of the straight groove-shaped recess,
It becomes difficult for the heat generated during braking to be transferred from the back metal to the piston. As a result, the temperature of the oil that presses the piston is prevented from rising, making vapor lock less likely to occur.

(2) Since the piston and the back metal contact each other only at two small circles, the piston can hold the back metal in a stable manner, and no noise is generated due to vibration of the pad during braking.

(3) As the linear groove-like concave portion of the backing metal is formed, the opposite side of the backing metal surface bulges out in the form of a linear groove, so that the bond between the lining and the backing metal that is pasted over the bulging portion is strengthened. This eliminates the risk of the lining peeling off from the back metal even if a shearing force is applied to the lining during braking.

(4) Forming a linear groove-shaped recess and a linear protrusion-shaped bulge on the back metal can be easily done by pressing.

[Brief explanation of drawings]

Figure 1 is a partial longitudinal side view of the disc brake.
FIG. 2 is a perspective view showing an embodiment of the present invention. 1: Piston, 2: Pad, 3: Back metal, 4: Rotor, 5: Lining, 6: Cylinder, 7: Back metal, 8: Lining, 9: Pad, 10: Recess,
11: Swelling part.

Claims (1)

[Claims] 1 A pad that is attached to a disc brake equipped with a parking brake mechanism, and the back metal of this pad has two partial circles a of a small area on both side edges with a large gap between the edges on both sides on the side facing the piston. , a has a linear groove-like recess extending in the radial direction of the piston that comes into contact with the piston end face only at points a, and this recess is formed by bulging the back metal in a linear protrusion toward the rotor. Features a disc brake pad.