JP2002054738A - Brake piston - Google Patents

Abstract

(57) [Summary] [Problem] To provide a piston which is lightweight and whose surface treatment can be inexpensive, and furthermore, it is easy to stabilize operation feeling. The surface of a piston made of an aluminum material is anodized and then impregnated with Teflon (registered trademark) to form a surface treatment layer. The rolling seal 8 that is in sliding contact with the surface treatment layer 14 is directly in contact with the surface treatment layer 14 without applying Teflon coating or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low friction piston used for a brake caliper of a hydraulic brake provided in a motorcycle or the like.

[0002]

2. Description of the Related Art A brake caliper of a hydraulic brake is provided with a liquid chamber and a cylinder hole communicating with the liquid chamber in a caliper body, and a piston is accommodated in the cylinder hole so as to be able to move forward and backward and a sliding surface with the cylinder hole. Is sealed with an annular piston seal fixed in the cylinder bore. This piston seal elastically deforms while sealing the pressurized liquid in the liquid chamber during braking and allows the piston to move in the direction of the disk rotor. When the hydraulic pressure in the liquid chamber is released by releasing the brake, the elasticity of the piston is restored. To retract the piston.

Therefore, since friction between the piston and the piston seal greatly affects the operation feeling, various low friction structures for sliding between the piston and the piston seal have been studied. For example, a surface treatment made of Ni plating and Teflon has been studied. Some are provided with a layer (Japanese Unexamined Patent Publication No.
-63047). It is also known that the piston is formed of an aluminum material, the surface is anodized to contain molybdenum, and the piston seal side is coated with Teflon.

[0004]

[0005] By the way, the plating method as in the conventional example requires a special treatment containing Teflon, so that the cost is high. Further, if iron is used as the material of the piston, the weight of the piston increases accordingly. On the other hand, when the piston is made of a molybdenum-containing alumite treatment, a Teflon coating is required for the piston seal and the number of steps is increased, so that the cost is increased. In addition, the piston seal gives a good operation feeling by a light movement of the piston during braking and a quick return of the piston when the braking is released, but in such a configuration, a stable operation feeling is obtained. Is difficult. Therefore, an object of the present invention is to provide a piston that can be manufactured lightly and inexpensively and can stabilize the operation feeling.

[0005]

In order to solve the above-mentioned problems, a brake piston according to the present invention is housed in a cylinder hole provided in a caliper body, and has an annular piston seal fixed on the outer peripheral surface into the cylinder hole. In the brake piston provided with a sliding seal surface that slides in contact with the brake piston, the whole is formed of an aluminum material, the outer peripheral surface of the piston is subjected to alumite treatment, and the sliding seal surface is formed by further impregnating with Teflon. I do.

[0006]

According to the present invention, the outer surface of the piston made of aluminum material is subjected to alumite treatment, and the recess formed in the treated layer is impregnated with Teflon, so that the piston can be reduced in weight and the aluminum material can be alumite-treated. A hard surface treatment layer can be formed by utilizing this, and a low friction surface can be obtained by impregnating the recess with Teflon.
In addition, the cost can be significantly reduced as compared with the surface treatments of the conventional example.

In addition, the need for coating Teflon on the piston seal side is eliminated, so that man-hours can be reduced, the balance between the surface treatment layer of the piston and the sliding portion of the piston seal can be easily maintained, and the operation feeling can be stabilized.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment will be described below with reference to the drawings. 1 is an external view of a brake caliper to which the present embodiment is applied, FIG. 2 is a cross-sectional view taken along the line 2-2, FIG. 3 is an enlarged schematic diagram of a main part, and FIG. 4 is an enlarged schematic diagram of a surface treatment layer. It is.

In FIG. 1 and FIG. 2, the brake caliper comprises a pair of left and right caliper bodies 1, 1 opposed to each other and connected by bolts 2, 2, 2, 2.
At 4, it is attached to the vehicle body (not shown). Cylinder holes 5 and 5 and liquid chambers 6 and 6 are formed to communicate with the caliper bodies 1 and 1 on the bottom side thereof, and the cylinder holes 5 and 5 are open on the opposite side.

A piston 7 is slidably housed in each of the cylinder holes 5, 5, and its outer peripheral surface forms a sealing surface, and an annular rolling seal 8 and a dust seal 9 slide on the sealing surfaces of the pistons 7, 7. ing. The rolling seal 8 and the dust seal 9 constitute a piston seal,
Each is fitted in an annular groove formed on the inner peripheral surface near the opening of the cylinder hole 5.

The rolling seal 8 is resiliently contacted with the outer periphery of the piston 7, and when the piston 7 moves in the direction protruding from the cylinder hole 5 due to the increase of the liquid pressure in the liquid chamber 6, it is allowed to move while being elastically deformed. Then, when the liquid pressure in the liquid chamber 6 is released, the piston 7 is caused to return by the restoring elasticity. On each opposing surface side of the pistons 7, 7, a friction plate 1
0, 10 are arranged so as to sandwich the disk rotor 11,
It is hung by a hanger pin 12 provided between the upper portions of the caliper bodies 1 and 1 and is slidable in the axial direction.

At the time of braking, the hydraulic pressures in the left and right liquid chambers 6 and 6 increase, and the pistons 7 and 7 move so as to approach each other, thereby pressing the friction plates 10 and 10 against both the left and right surfaces of the disk rotor 11. When the brake is released, the hydraulic pressure is released, so that the pistons 7, 7 are retracted as described above, and accordingly, the friction plates 10, 10 are separated from the disk rotor 11.

As shown in FIGS. 3 and 4, the surface of the piston 7 is subjected to a surface treatment. That is, the piston 7
Is made of an aluminum material, the outer surface of a base material 13 of which is anodized, and a surface treatment layer 14 impregnated with Teflon is formed. The rolling seal 8 and the dust seal 9 are not specially treated such as Teflon coating, but are generally made of a known material such as rubber or elastomer.

FIG. 4 shows the surface treatment layer 14 formed on the base material 13.
The surface treatment layer 14 is formed by alumite treatment and Teflon impregnation treatment. The alumite treatment is a generally known method, for example, 0 ° C.
A hard alumite layer is formed on the surface of the base material 13 by applying a direct current in an electrolytic solution of about 5 ° C. for a predetermined time. The thickness of the hard alumite layer can be arbitrarily adjusted depending on the processing conditions.

The hard alumite layer thus obtained can have a sufficiently high surface hardness, and thus substantially satisfies desired physical properties such as hardness for use as a piston. However, the hard alumite layer has poor lubricity because it has the concave portion 15 composed of many micropores. Therefore,
Teflon is impregnated after alumite treatment.

This impregnation can be carried out by a conventional method.
As a result, the Teflon 16 is introduced into the recess 15 of the alumite treatment layer.
Is filled. The filled Teflon 16 imparts sufficient lubricity to the surface of the alumite-treated layer, reduces the friction of the surface, and can, for example, reduce the friction coefficient to about 0.10 μm. This is better than about 0.13 μ obtained in the case of the conventional example containing molybdenum. Therefore, the surface treatment layer 14 can simultaneously obtain sufficient surface hardness and lubricity required for the piston 7 made of aluminum.

Next, the operation of this embodiment will be described. Figure 3,
As shown in FIG. 4, the surface treatment layer 14 has low friction by impregnating the recesses 15 with Teflon 16, thereby enabling smooth sliding. Moreover, the surface treatment layer 14 having both sufficient surface hardness and lubricity can be easily formed by the alumite treatment and the subsequent Teflon impregnation treatment.

For this reason, it becomes significantly simpler than the conventional surface treatment such as plating. In addition, the use of an aluminum material makes it possible to reduce the weight of the whole, and enables an inexpensive alumite treatment. Further, by impregnating with Teflon, the friction can be reduced as compared with the conventional example in which molybdenum is contained. As a result, it is not necessary to apply Teflon coating to the rolling seal 8, so that the number of steps can be reduced.

In addition, since the sliding portion is constituted by a combination of the rolling seal 8 having no Teflon coating and the surface treatment layer 14 which has been subjected to the alumite treatment impregnated with Teflon, it is easy to balance the sliding, and as a result, the brake A good operation feeling at the time of operation can be obtained, and the operation feeling can be stabilized.

[Brief description of the drawings]

FIG. 1 is an external view of a brake caliper to which the present embodiment is applied.

FIG. 2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is an enlarged schematic view of a main part.

FIG. 4 is a schematic diagram in which a cross section of a surface treatment layer is enlarged.

[Explanation of symbols]

1: Caliper body, 5: Cylinder hole, 6: Liquid chamber, 7:
Piston, 8: rolling seal, 9: dust seal,
13: Base material, 14: Surface treatment layer, 15: Concavity, 16: Teflon

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor ▲ Kuwa ▼ Shinichi 1-4-1 Chuo, Wako-shi, Saitama Prefecture Inside Honda R & D Co., Ltd. (72) Inventor Hiroshi Noro 1-chome, Chuo, Wako-shi, Saitama No.4-1 F term in Honda R & D Co., Ltd. (Reference) 3J044 AA06 AA18 BA04 BB11 BB37 BC01 DA12 3J058 AA43 AA48 AA53 AA66 AA69 AA74 AA77 AA84 AA87 BA19 BA61 BA68 CC35 CC36 EA08 EA13 EA31 EA36 FA

Claims (1)

[Claims] 1. A brake piston, which is housed in a cylinder hole provided in a caliper body and has a sliding seal surface on its outer peripheral surface which is in sliding contact with an annular piston seal fixed into the cylinder hole, the whole of which is made of aluminum material. A sliding piston formed by forming an alumite treatment on an outer peripheral surface thereof and further impregnating with Teflon to form the sliding seal surface.