JPS6242610Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tandem master cylinder used in a hydraulic brake system, and more particularly to a tandem master cylinder having a single reservoir in the cylinder body.

Conventionally, as shown in Japanese Utility Model Publication No. 53-35662, this type of tandem type master cylinder has a primary piston and a secondary piston slidably fitted into a cylinder hole of a cylinder body.
The primary piston defines a first hydraulic pressure chamber and a first liquid chamber, and the secondary piston defines a second hydraulic chamber.
a first hydraulic chamber defining a hydraulic pressure chamber and a second hydraulic chamber, comprising a single reservoir communicating with each of the hydraulic pressure chambers and the liquid chamber at an upper portion of the cylinder body, and defined by a primary piston; The first liquid chamber communicates with the reservoir through a relief port and a supply port provided at the bottom of the reservoir, and a second liquid chamber and a second hydraulic pressure chamber defined by a secondary piston separated from the reservoir communicate with the reservoir. and a relief port and a supply port communicating with the reservoir, respectively. It is known that a stopper bolt is screwed onto the lower side of the cylinder body, and its tip abuts against a secondary piston to limit the retraction limit of the piston that is pushed rearward by a return spring.

However, since the reservoir is single, in order to communicate the reservoir with the second hydraulic pressure chamber and the second liquid chamber that are separated from the reservoir, the communication fluid path must be formed in the cylinder axial direction at the top of the cylinder body. ,
The second hydraulic pressure chamber and the second
Relief ports and supply ports for the liquid chamber must be drilled in the upper part of the cylinder body, and ball seals must be fitted into the holes for forming the respective ports in the upper wall of the communicating liquid passage to seal them. In addition, it was necessary to specifically drill holes in the lower part of the cylinder body into which the stopper bolts were screwed, and machining these holes was time-consuming.

Therefore, an object of the present invention is to seal a hole for forming a supply port leading to the second liquid chamber, which is formed in the upper wall of the communication liquid passage, with a stopper bolt that restricts the retraction limit of the secondary piston. To provide a tandem type master cylinder that reduces the number of steps for drilling holes in a main body, has a simple structure, and reduces manufacturing costs.

In accordance with the above object, the present invention provides the tandem master cylinder having a single reservoir and a communication fluid path that communicates the single reservoir with a second fluid pressure chamber and a second fluid chamber defined by a secondary piston. , the shaft of the stopper bolt is loosely inserted into the supply port leading to the second liquid chamber defined by the secondary piston through the supply port forming hole drilled in the upper wall of the communication liquid passage, and its tip is inserted into the supply port formed by the second liquid chamber defined by the secondary piston. The stopper bolt protrudes into the second liquid chamber and comes into contact with the secondary piston to restrict the retraction limit of the secondary piston, and the base of the stopper bolt is screwed into the hole for forming the supply port to seal the hole. It is characterized by what it did.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

The cylinder body 1 has a cylinder hole 2 provided therein, and a primary piston 3 is slidably inserted into the opening 1a side of the cylinder body 1, and a secondary piston 4 is slidably inserted in front of the primary piston 3 (to the left in the figure). ing. The primary piston 3 has a piston cup 5 attached to its front part and a piston cup 6 to its rear part, and the secondary piston 4 has a piston cup 7 attached to its front part and a piston cup 8 to its rear part. It is being A first liquid chamber 9 is provided between the piston cups 5 and 6 of the primary piston 3, and a second liquid chamber 10 is provided between the piston cups 7 and 8 of the secondary piston 4.
However, a first hydraulic chamber 11 is provided between the piston cup 5 at the front of the primary piston 3 and the piston cup 8 at the rear of the secondary piston 4, and a first hydraulic pressure chamber 11 is provided between the piston cup 7 at the front of the secondary piston 4 and the front end wall of the cylinder hole 2. A second hydraulic chamber 12 is defined in each. A support pin 13 is screwed onto the front part of the primary piston 3 in the cylinder axial direction, and a retainer 14 is slidably provided on the shaft of the support pin 13. A receiving portion 14a of the retainer 14 that is engaged and prevented from coming off and abuts the rear part of the secondary piston 4.
A return spring 16 is compressed between the primary piston 3 and a spring seat 15 that comes into contact with the front part of the primary piston 3. When the primary piston 3 is not in operation, the retainer 14 is in contact with the rear part of the secondary piston 4, and the primary piston 3 is not pushed in the backward direction. Further, the secondary piston 4 is pushed rearward by a return spring 17 compressed between the front end wall of the cylinder hole 2 and the secondary piston 4, and comes into contact with a stopper bolt 18 screwed into the cylinder body 1 to reach the backward limit. regulated. In this state, the first liquid chamber 9 defined by the primary piston 3 passes through the supply port 19,
The first hydraulic chamber 11 also communicates with a compartment 21a in the reservoir 21 through a relief port 20. On the other hand, the second fluid chamber 10 defined by the secondary piston 4 passes through a supply port 22, and the second fluid pressure chamber 12 passes through a relief port 23, and is further connected to a compartment in the reservoir 21 via a communication fluid path 24. 21b. In addition, the first and second hydraulic chambers 11 and 12
is provided with a discharge port.

The communication fluid passage 24 that communicates the reservoir 21 with the second fluid chamber 10 and the second fluid pressure chamber 12 that are separated from the reservoir 21 is connected to the reservoir 21 from the front in the thick part 25 of the upper part of the cylinder body 1. compartment 21b
It is formed by drilling in the axial direction of the cylinder.
Further, a supply port 22 and a relief port 23 are bored in the upper part of the cylinder body 1 from the upper wall of the communication liquid passage 24 through the communication liquid passage 24 to open into the second liquid chamber 10 and the second hydraulic pressure chamber 12 . Then, the tip opening 24a of the communicating liquid path 24 and the hole 23a for forming the relief port 23 formed in the upper wall of the communicating liquid path 24 are sealed by press-fitting ball seals 26 and 27, respectively.

A hole 22a for forming the supply port 22, which is formed in the upper wall of the communication liquid path 24, has a large diameter, and the stopper bolt 1 is inserted through the hole 22a.
The shaft portion 18a of the secondary piston 4 is loosely inserted into the supply port 22 so that its tip 18b projects into the second liquid chamber 10, and is brought into contact with the inside of the collar portion 4a of the secondary piston 4 to restrict the backward limit of the secondary piston 4. There is. The base portion 18c of the stopper bolt 18 is screwed into the hole 22a to seal the hole 22a.

Next, the operation of this embodiment will be explained. When a push rod (not shown) is moved forward (to the left in the figure) for actuation, the primary piston 3 advances and the piston cup 5 closes the relief port 20, thereby opening the first hydraulic chamber 11.
The hydraulic fluid is trapped and hydraulic pressure is generated. This hydraulic pressure is supplied from the discharge port to the actuating device of one system. At the same time, this hydraulic pressure presses the secondary piston 4, which moves forward against the return spring 17, causing the piston cup 7 to close the relief port 23.
Then, in the same manner as described above, the hydraulic fluid in the second hydraulic pressure chamber 12 is confined to generate hydraulic pressure, and this hydraulic pressure is supplied to the actuating device of the other system through the discharge port. In this operating state, the return spring 16 contracts and the primary piston 3 moves to the left,
Further, the return spring 17 is contracted and the secondary piston 4 is in a position moved to the left, so that the collar portion 4a of the secondary piston 4 and the tip 18b of the stopper bolt 18 are no longer in contact with each other.

Then, when the push rod is moved back and the operation is released, the primary piston 3 and the secondary piston 4 are activated by their respective return springs 16,
17, it is pushed backward and returns to the position shown in the figure. At this time, the collar portion 4a of the secondary piston 4 contacts the tip 18b of the stopper bolt 18 and does not move back any further. Also, the primary piston 3 is pushed backward by the action of the return spring 16, but the return spring 1
Since the extension of the primary piston 3 is restricted by the support pin 13 and the retainer 14 slidably engaged with the support pin 13, it is necessary to provide a stopper member near the cylinder opening 1a to restrict the retraction limit of the primary piston 3. By restricting the backward limit of the secondary piston 4 with the stopper bolt 18, the backward limit of the primary piston 3 is simultaneously restricted.

In the illustrated embodiment, the shaft portion 18a of the stopper bolt 18 is loosely inserted into the center of the supply port 22, but it may be made to abut against the inner wall of the supply port 22 on the primary piston 3 side. In this way, when the secondary piston 4 comes into contact with the shaft portion 18a, the actual length of the shaft portion 18a becomes short and it becomes difficult to deform, and the shaft portion 18a is bent due to the retreat of the secondary piston 4. Furthermore, it is possible to effectively prevent deformation of the threaded portion of the base portion 18c and deterioration of sealing performance.

As described above, the present invention loosely inserts the shaft portion of the stopper bolt into the supply port leading to the second liquid chamber defined by the secondary piston through the supply port forming hole formed in the upper wall of the communication liquid passage. The tip of the stopper bolt protrudes into the second liquid chamber and comes into contact with the secondary piston to restrict the retraction limit of the secondary piston, and the base of the stopper bolt is screwed into the hole for drilling the supply port. After the hole is sealed, the mechanism for restricting the backward movement of the secondary piston and the mechanism for sealing the hole for forming the supply port leading to the second liquid chamber defined by the secondary piston are closed by screwing the stopper bolt. It can be prepared at the same time, reducing the process of drilling holes in the cylinder body and the process of sealing it.
It has a simple structure and has the advantage of being able to reduce manufacturing costs.

[Brief explanation of the drawing]

The figure is a cross-sectional front view of a tandem-type master cylinder showing an embodiment of the present invention. 1...Cylinder body, 2...Cylinder hole, 3...
...Primary piston, 4...Secondary piston, 18...Stopper bolt, 21...Reservoir, 19, 22...Supply port, 20, 23
... Relief port, 24 ... Communication fluid path.

Claims (1)

[Scope of utility model registration request] A primary piston and a secondary piston are slidably fitted into the cylinder hole of the cylinder body,
The primary piston defines a first hydraulic pressure chamber and a first liquid chamber, and the secondary piston defines a second hydraulic chamber.
defining a hydraulic pressure chamber and a second hydraulic chamber, and comprising a single reservoir in an upper part of the cylinder body communicating with each of the hydraulic pressure chambers and each hydraulic chamber, the second hydraulic chamber being spaced apart from the reservoir and the reservoir; A communication fluid path connecting the fluid chamber and the second fluid chamber is formed in the cylinder axial direction in the upper part of the cylinder body, and a relief port and a supply are connected to the second fluid pressure chamber and the second fluid chamber from the upper wall of the fluid fluid channel. In a tandem type master cylinder in which a port is drilled and a hole for forming a relief port and a supply port drilled in the upper wall of the communication liquid passage is sealed, the shaft portion of the stopper bolt is drilled for forming the supply port. It is loosely inserted into the supply port communicating with the second liquid chamber through the hole, and its tip projects into the second liquid chamber and comes into contact with the secondary piston to restrict the retraction limit of the secondary piston, and the base of the stopper bolt is A tandem-type master cylinder, characterized in that the tandem-type master cylinder is screwed into the hole for forming the supply port to seal the hole.