JPH0569816A - Manufacture of cylinder body for tandem type master cylinder - Google Patents

Abstract

PURPOSE:To form a communication passage in a simple manner by forming a closed end hole constituting almost the whole portion of the communication passage in such a way that its blocked end forms a wall section projecting into an oil bank with a core inserted when material for a cylinder is casted, and thereby cutting a part of the wall section from the oil bank side after casting has been done, so that its inner end is communicated with the inside of the oil bank. CONSTITUTION:Material 1' for a cylinder is casted into a closed end cylindrical shape integrated with an oil bank 6, and an closed end hole 20 corresponding to a communication passage 14 is formed with a bar shaped core 18 inserted at the time of casting. In this case, the core for forming the oil bank 6 is formed in such a way that the blocked end of the closed end hole 20 forms a wall section 19 projecting into the lower section of the inside of the oil bank 6. A communication hole 21 communicating the irmer end of the closed end hole 20 with the inside of the oil bank 6, is bored in the upper portion of the wall section 19. The communication passage 14 is formed out of the communication hole 21 and of the closed end hole 20. Working processes can be lessened in number after casting has been done as compared with a cylinder body in which the communication passage is bored through the whole length of the passage after the material for the cylinder has been casted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is formed in a cylindrical shape having a bottomed cylinder hole into which a pair of front and rear pistons are slidably fitted, and an axis extending in a direction intersecting the axis of the cylinder hole. Bottom having an oil sump in order to form a cylinder body having an oil sump and a communication passage communicating with the oil pressure chamber formed between the pistons The present invention relates to a method for manufacturing a cylinder body for a tandem type master cylinder which is made by casting a cylindrical cylinder material.

[0002]

2. Description of the Related Art Conventionally, such a cylinder body for a tandem type master cylinder is already known, for example, from Japanese Utility Model Laid-Open No. 2-12969, and an oil sump is integrally formed when forming a communication passage in the cylinder body. The bottomed cylindrical cylinder material to be cast is perforated from the opening end side thereof, or a cylinder material having a communication passage is cast using a core.

[0003]

However, in the case where the cylinder material after casting is perforated, the manufacturing cost naturally increases accordingly, and in the case where the communication passage is formed by the core, the oil cost is increased. It is unavoidable that the core for forming the reservoir and the core for forming the communication passage come into contact with each other, and the core for forming the communication passage is bent, and the film that is formed between the contact surfaces of both cores is removed. Will be needed.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method of manufacturing a tandem type master cylinder cylinder body capable of easily forming a communication passage.

[0005]

In order to achieve the above object, according to the present invention, when a cylinder material is cast, a bottomed hole forming a large part of a communication passage is formed by inserting a core, and the closed end thereof is formed. Is formed as a wall protruding into the oil reservoir,
After casting, at least a part of the wall portion is cut off from the oil reservoir side to form a communication passage having an inner end communicating with the oil reservoir.

[0006]

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

1 to 3 show an embodiment of the present invention. FIG. 1 is a vertical sectional side view of a tandem master cylinder, FIG. 2 is a vertical sectional view of a cylinder material at the time of completion of casting, and FIG. It is a longitudinal cross-sectional view of a cylinder body.

First, in FIG. 1, a tandem master cylinder M for a vehicle brake is provided with a cylinder body 1, and a bottomed cylinder hole 2 provided in the cylinder body 1 includes:
A pair of front piston 3 ₁ and rear piston 3 ₂ are slidably fitted, and a front hydraulic chamber 4 ₁ is formed between the closed end of the cylinder hole 2 and the front piston 3 ₁ , and both pistons 3 1 _A rear hydraulic chamber 4 ₂ is formed between ₁ and 3 ₂ . Thus to the hydraulic chambers 4 _1, 4 ₂ are connected to the brake hydraulic circuit of the two systems in motor vehicles. Moreover, the pistons 3 ₁ , 3 ₂ are biased to the retracted positions by the return springs 5 ₁ , 5 ₂ , respectively, and the rear end of the rear piston 3 ₂ is connected to the output rod of the negative pressure booster (not shown).

[0009] The upper portion of the cylinder body 1 are those reservoir R is provided, the reservoir R is the front hydraulic chamber 4 ₁
A cylindrical oil sump 6 that is integrally provided on the upper part of the cylinder body 1 so as to intersect the axis of the cylinder hole 2 at an angle of 90 degrees at a position adjacent to the oil sump 6, and the outer circumference of the oil sump 6. And a reservoir body 7 made of synthetic resin, the lower end portion of which is fitted and connected. Moreover, the inside of the oil sump 6 is divided into a front oil sump chamber 6 ₁ and a rear oil sump chamber 6 ₂ by the partition wall 11 integrated with the cylinder body 1. Thus, the front oil reservoir chamber 6 ₁ is arranged directly above the front piston 3 ₁ , and its bottom wall is
Front hydraulic chamber 4 _first relief port 12 ₁ and the supply port 13 ₁ is drilled.

On the other hand, behind the upper part of the cylinder body 1, there is provided a thick side wall 1a continuing to the oil sump 6, and this side wall 1a.
The communication passage 14 is closed the rear end in the sphere 15 with communicating an inner end to the rear oil reservoir chamber 6 ₂ are provided. Further, the relief port 12 ₂ and the supply port 13 _{2 of the} rear hydraulic chamber 4 ₂ are formed in the side wall 1 a so as to intersect the rear portion of the communication passage 14 in a cross shape.
The outer ends of ₂ and 13 ₂ are closed by spheres 16 and 17, respectively.

In manufacturing the cylinder body 1 of such a tandem master cylinder M, a cylinder material 1'as shown in FIG. 2 is cast. This cylinder blank 1'is cast into a bottomed tubular shape having an oil sump 6 integrally, and at the time of casting, a rod-shaped core 18 is inserted to form a bottomed hole 20 corresponding to the communication passage 14. It is formed. Moreover, the core for forming the oil reservoir 6 is formed so that the closed end of the bottomed hole 20 becomes the wall portion 19 that projects into the lower portion of the oil reservoir 6.

After the cylinder blank 1'is obtained by the above-mentioned casting, as shown in FIG. 3, the cylinder hole 2 is ground and the relief ports 12 ₁ and 12 ₂ and the supply ports 13 ₁ and 13 ₂ are drilled. As it is implemented,
A drill 22 is inserted into the oil sump 6 from its open end, and a communication hole 21 for communicating the inner end of the bottomed hole 20 with the oil sump 6 is bored in the upper portion of the wall portion 19. The communication hole 21 and the bottomed hole 2
At 0, the communication passage 14 is formed.

In this way, the bottomed hole 20 is formed at the time of casting the cylinder blank 1 ', and a part of the wall portion 19 which is the closed end of the bottomed hole 20 is cut off to form the bottomed hole 2
Since 0 is communicated with the oil reservoir 6 to form the communication passage 14, the number of working steps after casting is smaller than that in which the communication passage is drilled over its entire length after the cylinder material is cast. Further, as compared with the case where the communication passage is formed at the time of casting, the core is not worn and the removal work of the film generated between both cores is unnecessary.

When cutting off the wall portion 19, as shown in FIG. 4, most of the wall portion 19 may be cut off by a drill 23.

[0015]

As described above, according to the present invention, when a cylinder material is cast, a bottomed hole forming a large part of the communication passage is inserted into the wall by the insertion of the core, the closed end of which projects into the oil reservoir. Since at least a part of the wall is cut off from the oil sump side after casting to form a communication passage having the inner end communicating with the oil sump, it is connected after the cylinder material is cast. It is easier to form the communication passage than the one that drills the passage over its entire length, and it reduces the wear of the core and the film removal work compared to the one that forms the communication passage at the same time when casting the cylinder material. It is possible to reduce the work man-hours by eliminating the need for.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view of a tandem type master cylinder according to an embodiment.

FIG. 2 is a vertical cross-sectional view of a cylinder material when casting is completed.

FIG. 3 is a vertical sectional view of a cylinder body.

FIG. 4 is a cross-sectional view corresponding to FIG. 3 for showing a modification of the method of cutting the wall portion.

[Explanation of symbols]

1 Cylinder body 1'Cylinder material 2 Cylinder hole 3 ₁ , 3 ₂ Piston 4 ₂ Hydraulic chamber 6 Oil reservoir 14 Communication passage 18 Core 19 Wall part 20 Bottomed hole M Tandem type master cylinder

Claims (1)

[Claims] 1. A bottomed cylinder hole (2) into which a pair of front and rear pistons (3 ₁ , 3 ₂ ) are slidably fitted, and an axis line extending in a direction intersecting the axis line of the cylinder hole (2). The oil reservoir (6) having a cylindrical shape and a hydraulic chamber (4 ₂ ) formed between the pistons (3 ₁ , 3 ₂ ) can communicate with each other in the oil reservoir (6). Communication passage (1
4) a tandem type master cylinder cylinder body having a bottomed cylindrical cylinder material (1 ') integrally formed with an oil sump (6) to form a cylinder body (1) having In the manufacturing method, when the cylinder material (1 ') is cast, the closed end (20) of the bottomed hole (20) forming the majority of the communication passage (14) is inserted into the core (18) so that the closed end of the oil reservoir (6). The wall portion (19) is formed so as to project inward, and after casting, the wall portion (1) is formed from the oil sump (6) side.
A method for manufacturing a tandem type master cylinder cylinder body, characterized in that at least a part of (9) is cut off to form a communication passage (14) having an inner end communicating with an oil reservoir (6).