JPH0596576U - Disc brake - Google Patents

Abstract

(57) [Summary] [Purpose] To enable filling of brake fluid by a vacuum filling method without sacrificing manufacturability. [Structure] A convex portion 9 for opening an oil supply port 5 is provided on an inner bottom surface of a cylinder 2 formed in a caliper 1, and grooves 15a, 15b are provided on a bottom surface of a piston 3 slidably fitted in the cylinder 2.
In the state where the piston 3 is bottom-butted to the cylinder 2, through the grooves 15a, 15b and the gap 12 between the bottom surface of the piston and the bottom surface of the cylinder, between the oil supply port 5 and the passage 6 to which the bleeder is attached. Communicate.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a disc brake mounted on a vehicle such as a motorcycle.

[0002]

[Prior Art]

 One type of disc brake is one that has a lubrication port at the bottom of the cylinder formed on the caliper. FIGS. 5 and 6 show such a disc brake by taking a caliper fixed type as an example. 1 is a caliper, 2 is a cylinder formed in the caliper 1, 3 is a seal member 4 attached to the cylinder 2. The pistons are slidably fitted through the respective pistons. The bottom of the cylinder 2 is provided with a filler port 5 and a bleeder passage 6. The filler port 5 leads to a pipe boss 7 projecting in the center of the rear face of the caliper 1, and the bleeder passage 6 is also the upper rear face of the caliper 1. It communicates with a bleeder boss 8 to which a bleeder (illustration) is attached.

A pipe extending from a master cylinder (not shown) is connected to the pipe boss 7, and pressure oil (brake fluid) sent from the master cylinder is introduced into the cylinder 2 from the oil supply port 5. As a result, the piston 3 moves forward, and a pad (not shown) arranged at the front part of the piston 3 is pressed against a disk (not shown) which rotates integrally with the wheel. In the case of the fixed caliper type, a similar cylinder is also installed on the opposite side of the disk, and pressure oil from the master cylinder also passes through the communication passage (not shown) to the opposite cylinder. Then, the other pad is simultaneously pressed against the disk by the piston fitted in the cylinder.

By the way, as a method of filling the brake fluid into the disc brake, a so-called vacuum filling is performed in which the brake fluid is supplied from the same side after the master cylinder side or the bleeder side is evacuated to remove air in the path. There is a system, and rapid filling is possible, so it has been widely used in recent years. However, when this method is applied to the above-mentioned disc brake, since the bottom of the cylinder 2 has the oil supply port 5, if the piston 3 is in close contact with the inner bottom surface of the cylinder 2, the air bleeding by vacuuming will be insufficient. , Its application becomes impossible.

Therefore, conventionally, as shown in FIG. 6 described above, a convex portion 9 for opening the oil supply port 5 is provided on the inner bottom surface of the cylinder 2, and the piston 3 is seated on the convex portion 9. A plurality of notches 10 are provided on the convex portion 9 in the circumferential direction so as to be equally distributed, and a concave portion 11 is provided on the bottom surface of the piston 3. With such a configuration, even if the piston 3 bottom-projects to the cylinder 2, the recesses 11 on the bottom surface of the piston 3 and the notches in the projection 9 are provided between the oil supply port 5 and the cylinder 2 or the bleeder passage 6. The gap 10 between the inner bottom surface of the cylinder 2 and the bottom surface of the piston 3 communicates with each other to allow the brake fluid to be filled by the vacuum filling method. A similar structure is disclosed in Japanese Utility Model Laid-Open No. 2-44131.

[0006]

[Problems to be solved by the device]

 However, according to the above-mentioned conventional vacuum filling structure, since the notch 10 provided in the protrusion 9 cannot be formed by cutting due to the positional restriction, the notch 10 is formed by casting in accordance with the casting of the caliper 1. As a result, there has been a problem that the core shape used in the casting of the caliper 1 becomes complicated, the manufacturing thereof becomes troublesome, and an increase in casting cost cannot be avoided.

The present invention has been made in view of the above conventional problems, and an object of the present invention is to provide a disc brake capable of effectively responding to the filling of the brake fluid by the vacuum filling method without impairing the manufacturability. .

[0008]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention has a piston formed slidably in a cylinder formed in a caliper, and has a lubrication port and a bleeder passage communicating with a bleeder at the bottom of the cylinder. In the disc brake in which the piston is advanced by pressing the pad against the disc by the pressure oil introduced from above, the inner bottom surface of the cylinder is provided with a convex portion on which the piston is seated and the oil supply port is opened, It is characterized in that at least one groove is formed on the bottom surface of the piston so that one end of the oil supply port in the convex portion and the other end face the cylinder bottom surface around the convex portion, respectively.

[0009]

[Action]

 In the disc brake configured as described above, the oil filler opening in the convex portion is communicated with the inside of the cylinder and the bleeder passage through the groove provided on the bottom surface of the piston and the gap between the bottom surface of the cylinder and the bottom surface of the piston. Therefore, it becomes possible to fill the break liquid by the vacuum filling method. Moreover, since the convex portion is simply provided on the bottom of the cylinder, it is not necessary to use a core having a complicated shape when casting the caliper.

[0010]

【Example】

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

FIG. 1 and FIG. 2 show a main structure of a disc brake according to the present invention. The present embodiment is intended for the same caliper fixed type as shown in FIGS. 3 to 5, and the same parts as those shown in the respective drawings are designated by the same reference numerals. I will. In the present embodiment, the notch 10 (FIG. 6) is abolished from the convex portion 9 provided on the inner bottom surface of the cylinder 2, while the pair of grooves 15a and 15b extending in the radial direction is provided on the bottom surface of the piston 3. ing. Each of the grooves 15a and 15b has a width W that is almost the same as the diameter of the filler port 5, one end of the filler port 5 in the convex portion 9 and the inner bottom surface of the cylinder 2 around the convex portion 9 The other end is facing each other. Further, the pair of grooves 15a and 15b are arranged so as to form a straight line in the axial radial direction to form one long groove 15.

In the disc brake configured as described above, even if the piston 3 bottom-bottoms into the cylinder 2, the long groove 15 on the bottom surface of the piston 3 is provided between the fuel filler port 5 and the inside of the cylinder 2 and the bleeder passage 6. , The cylinder 2 and the bottom surface of the piston 3 communicate with each other through a gap 12. Therefore, it is possible to evacuate the air from the master cylinder side or the bleeder side to sufficiently remove the air in the path, and it is possible to fill the brake fluid by the so-called vacuum filling method. Moreover, since the notch 10 is omitted from the convex portion 9 on the inner bottom of the cylinder 2, it is not necessary to use a core having a complicated shape in casting the caliper 1, and the caliper 1 is easily manufactured. Casting cost is reduced.

In the above embodiment, the groove provided on the bottom surface of the piston 3 is composed of a pair of grooves 15a and 15b forming the long groove 15. However, the number and arrangement relationship of the grooves are arbitrary, and for example As shown in FIG. 3, it is composed of a large number (four in this case) of grooves 16a, 16b, 16c, 16d which are equally arranged in the circumferential direction, or as shown in FIG. It can be composed of a large number of grooves 17a, 17b, 17c, 17d which are equally distributed in the center and which are integrated at the center so as to form a cross shape. When the piston 3 is forged as shown in Fig. 3 and Fig. 4, when the piston 3 is forged, the flow of material to the bottom corners is promoted, and the piston with excellent shape accuracy is stabilized. Obtainable.

[0013]

[Effect of the device]

 As described above in detail, according to the disc brake of the present invention, it is possible to effectively cope with the filling of the brake fluid in the vacuum filling method, and it is easy to manufacture the core used for casting the caliper. It contributes to the improvement of manufacturability and its utility value is great.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a main structure of a disc brake according to the present invention.

FIG. 2 is a plan view showing a bottom surface shape of a piston according to the present invention.

FIG. 3 is a plan view showing a piston according to the present invention having a modified bottom shape.

FIG. 4 is a plan view showing a piston according to the present invention in which the bottom surface shape is further changed.

FIG. 5 is a front view showing an appearance of a conventional disc brake.

FIG. 6 is a sectional view showing a structure of a main part of a conventional disc brake.

[Explanation of symbols]

 1 Caliper 2 Cylinder 3 Piston 5 Oil Filling Port 6 Bleeder Passage 9 Projection 15a Groove 15b Groove

Claims (1)

[Scope of utility model registration request] 1. A piston is slidably fitted in a cylinder formed in a caliper, an oil supply port and a bleeder passage communicating with a bleeder are provided at the bottom of the cylinder, and the piston is supplied by pressure oil introduced from the oil supply port. In the disc brake in which the pad is pressed against the disc by advancing, the convex portion on which the piston is seated and the fuel filler port is opened is provided on the inner bottom surface of the cylinder, and the convex portion is formed on the bottom surface of the piston. At least 1 so that one end faces the oil supply port of the other end and the other end faces the inner bottom surface of the cylinder around the convex portion.
A disc brake with two grooves.