JP2519375Y2 - Master cylinder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a tandem type master cylinder equipped with a hydraulic control valve used in a brake system of an automobile.

(Prior Art) Conventionally, as a tandem type master cylinder used for a two-system brake of an automobile, a type integrally provided with a hydraulic pressure control valve for controlling the hydraulic pressure supplied to the front and rear wheels to a predetermined hydraulic pressure. It is known that, for example, the actual exploitation Sho 62-11296
There is one disclosed in Japanese Patent Publication No. 2 or Japanese Utility Model Publication No. 2-20134.

For example, as shown in FIG. 3, a tandem master cylinder 3 into which a primary piston 1 and a secondary piston 2 are slidably fitted is connected to a hydraulic control valve 4 having a control release mechanism. . The hydraulic pressure control valve 4 has a stepped piston 5 in which a communication hole is formed in the axial direction, and a valve 6 that opens and closes the communication hole as the stepped piston 5 moves back and forth.
Is provided. The valve 6 is provided with a notch or passage for communicating the inlet side of the hydraulic pressure control valve 4 and the stepped piston 5 side, and a slider 7 is provided facing the valve 6.
The pin 7a of the slider 7 is projectingly provided in the tandem type master cylinder 3, and a tubular member 8 having a flange portion 8a capable of contacting the pin 7a is fixed to one end of the secondary piston 2. A return spring 9 partially housed in the tubular member 8 is interposed between the primary piston 1 and the secondary piston 2, and a return spring 9 is provided between the secondary piston 2 and the bottom of the tandem master cylinder 3. 10 are installed. A brake system for the front wheels is connected to the flow port 11 on the secondary piston 2 side, and a brake system for the rear wheels is connected to the flow port 12 of the hydraulic control valve 4. In the figure, 13 and 14 are oil liquid passages connected to a reservoir (not shown).

With this configuration, when the primary piston 1 is pressed toward the secondary piston 2 side, the inlet side of the hydraulic pressure control valve 4 is pressurized and the secondary piston 2 causes the flow port 11
Is pressurized to almost the same pressure as the inlet side of the hydraulic control valve 4. The valve 6 opens and closes the communication hole of the stepped piston 5 as the stepped piston 5 moves back and forth according to the hydraulic pressure on the inlet side of the hydraulic pressure control valve 4, so that the hydraulic pressure of the outlet port 12 is The hydraulic pressure on the inlet side is reduced and transmitted to the brake system of the rear wheels. Further, the hydraulic pressure of the flow port 11 is directly transmitted to the brake system of the front wheels.

When the hydraulic pressure in the brake system of the front wheels decreases due to oil leakage or the like, the flange 8a moves when the tubular member 8 moves more than a predetermined stroke in the cylinder as the secondary piston 2 displaces largely to the left in the figure. The slider 7 is moved by contacting the pin 7a. Then, the slider 7 becomes the valve 6
The hydraulic pressure generated by the primary piston 1 is directly supplied to the brake system of the rear wheel by abutting against the valve 6 and tilting the valve 6 to separate it from the stepped piston 5. It will be. In this way, sufficient hydraulic pressure can be secured in the brake system for the rear wheels when the brake system for the front wheels fails.

(Problems to be Solved by the Invention) In the above-mentioned conventional master cylinder, since the tubular member 8 is provided with the flange portion 8a for moving the pin 7a of the control release mechanism of the hydraulic control valve 4, the tubular member 8 The outer diameter is set smaller than the inner diameter of the master cylinder 3. Therefore, there is a problem that the outer diameter of the return spring 9 housed in the tubular member 8 is restricted by the inner diameter of the tubular member 8 and the degree of freedom in setting is reduced.

The present invention has been made in view of the above points, and is a master cylinder in which the outer diameter of the cylinder member for operating the hydraulic pressure control valve release mechanism is made substantially equal to the inner diameter of the master cylinder by improving the above-mentioned conventional master cylinder. The purpose is to provide.

(Means for Solving the Problems) In order to solve the above-mentioned problems, a master cylinder of the present invention is provided in a cylinder of a tandem type master cylinder in which a pair of pistons are slidably fitted so as to project in the cylinder. Is connected to a hydraulic control valve whose operation is canceled by moving the pin in the axial direction of the cylinder, and a cylindrical member having a long hole in the axial direction is provided at one end of the piston to project into the cylinder. The pin provided is inserted into the elongated hole of the tubular member.

(Operation) With this configuration, when the piston is displaced more than the predetermined amount, the end of the long hole formed in the cylindrical member fixed to one end of the piston comes into contact with the pin protruding in the cylinder. The pin is moved in the axial direction of the cylinder to release the operation of the hydraulic control valve.

Further, since the pin protruding in the cylinder is inserted into the long hole formed in the cylindrical member, the outer diameter of the cylindrical member can be set to be substantially equal to the inner diameter of the master cylinder.

Embodiment An embodiment of the present invention will be described in detail below with reference to the drawings.

In FIG. 1, reference numeral 15 denotes a tandem type master cylinder body having a cylindrical shape with a bottom. A primary piston 16 is slidably inserted into an opening side of the master cylinder body 15 and a secondary piston 17 is slidably inserted into a bottom side thereof. It is fitted. A first pressure chamber 18 is formed between the primary piston 16 and the secondary piston 17, and a second pressure chamber 19 is formed between the secondary piston 17 and the bottom of the master cylinder body 15. A hydraulic control valve 20 is connected to the first pressurizing chamber 18, and communicates with the brake system of the rear wheels through the hydraulic control valve 20, and the second pressurizing chamber 19 communicates with the brake system of the front wheels. ing.

The hydraulic control valve 20 is provided with a stepped piston 21 in which a communication hole is formed in the axial direction, and a valve 22 that opens and closes the communication hole as the stepped piston 21 moves back and forth. A slider 23 is provided so as to face the valve 22, and a lower end of the slider 23 is inserted into an annular wall above the valve 22. And the slider 23
The pin 23a at the top of the is projected from the connection part with the hydraulic pressure control valve 20 in the master cylinder body 15, and the hydraulic pressure control is released by moving the pin 23a in the axial direction of the master cylinder body 15. It is supposed to do. Although the structure of the slider 23 is well known and will not be described in detail, the pin 23a is held in a predetermined position by a spring member and is supported so as to be slidable in the axial direction of the master cylinder body 15.

A cylindrical tubular member 24 is inserted between the primary piston 16 and the secondary piston 17 in the master cylinder body 15 and fixed to one end of the secondary piston 17. The outer diameter of the tubular member 24 is substantially equal to the inner diameter of the master cylinder body 15, and a pair of axially long slots 25 are bored at opposing portions of the side surfaces, and a pin 23a is inserted into one of the slots 25. ing. When the secondary piston 17 is displaced until it comes into contact with the bottom of the master cylinder body 15, the end of the elongated hole 25 comes into contact with the pin 23a.

 An enlarged cross section of the tubular member 8 is shown in FIG.

Between the primary piston 16 and the secondary piston 17, a return spring 26 is partially housed in the tubular member 24 and interposed. A return spring 27 is provided between the secondary piston 17 and the bottom of the master cylinder body 15.

At the end of the secondary piston 17 on the bottom side of the master cylinder body 15, a relief port valve mechanism 28 for replenishing the oil liquid in the second pressurizing chamber 19 is provided. When the secondary piston 17 is displaced to the oil replenishment position by the stopper 29 fixed to the master cylinder body 15 through the valve opening rod 30
The valve is opened by bringing into contact with. The stopper 29 regulates the rotation of the secondary piston 17.

In the figure, 31 and 32 are oil liquid passages connecting a reservoir (not shown), 33, 34, 35 and 36 are seal members, and 37 is a retainer.

The operation of the present embodiment configured as above will be described below.

Step on the brake pedal and push rod (not shown)
Primary piston 16 through return spring 2
When the secondary piston 17 side is pressed against the elastic force of 6,27, the oil liquids in the first pressurizing chamber 18 and the second pressurizing chamber 19 are pressurized to generate substantially the same hydraulic pressure. The hydraulic pressure in the first pressurizing chamber 18 is transmitted to the rear wheel brake system via the hydraulic pressure control valve 20.
At this time, the hydraulic pressure control valve 20 opens and closes the communication hole of the stepped piston 21 as the stepped piston 21 moves back and forth according to the hydraulic pressure on the inlet side (first pressurizing chamber 18), so that the outlet side is opened. The hydraulic pressure is controlled to be lower than the hydraulic pressure on the inlet side and transmitted to the brake system of the rear wheels. The hydraulic pressure in the second pressurizing chamber 19 is directly transmitted to the brake system for the front wheels. Therefore, the same hydraulic pressure as the hydraulic pressure in the second pressurizing chamber 19 is constantly transmitted to the brake system of the front wheels.

When the brake system of the front wheels fails and the hydraulic pressure in the second pressurizing chamber 19 decreases, the brake pedal is depressed and the primary piston 16 is moved to the spring 2 via a push rod (not shown).
When pressed against the secondary piston 17 side against the elastic force of 0, 21, the secondary piston 17 is displaced until it comes into contact with the bottom of the master cylinder body 15. Along with this, the tubular member 24 moves, the end of the long hole 25 contacts the pin 23a, and the slider 23 moves in the axial direction of the master cylinder body 15. Then, the slider 23 comes into contact with the valve 22 and tilts the valve 22 to separate it from the stepped piston 21, whereby the hydraulic pressure control of the hydraulic pressure control valve 20 is released. Therefore, the first pressurizing chamber
18 and the brake system for the rear wheels are directly connected to each other, and the hydraulic pressure in the first pressurizing chamber is directly transmitted to the brake system for the rear wheels without being pressure-reduced. In this way, sufficient hydraulic pressure can be secured in the brake system for the rear wheels when the brake system for the front wheels fails.

If the brake system of the rear wheels fails and the hydraulic pressure in the first pressurizing chamber drops, pressing the primary piston 16 via the push rod causes the primary piston 16 to move to the retainer 37.
Since the pressing force is transmitted to the secondary piston 17 via the, the hydraulic pressure is generated in the second pressurizing chamber 19, and this hydraulic pressure is transmitted to the front wheel brake system as it is.

Further, since the cylindrical member 24 is inserted into the master cylinder body 15 by inserting the pin 23a into the elongated hole 25, the outer diameter of the cylindrical member 24 can be made substantially the same as the inner diameter of the master cylinder body 15. Therefore, the diameter of the return spring 26 accommodated in the tubular member 24 can be set larger than that of the conventional one.

Furthermore, since the pair of elongated holes 25 are formed in the side surface portions of the cylindrical member 24 facing each other, the air in the cylindrical member 24 can be easily removed by the one elongated hole 25 located above.

Since the rotation of the secondary piston 17 is controlled by the stopper 29, the cylindrical member attached to the secondary piston 17
24 can be easily positioned.

In this embodiment, the slider 23 is shown as a separate body from the valve 22 for controlling the hydraulic pressure, but an integral body may be used. In this case, when the end of the long hole 25 comes into contact with the pin 23a, the pin 23a moves in the axial direction of the master cylinder body 15 so that the valve 22 is tilted together with the slider 23 and separated from the stepped piston 21. The hydraulic control of the pressure control valve 20 is released.

Further, the tubular member 24 is provided as a separate body from the secondary piston 17, but the tubular member and the secondary piston may be provided integrally.

(Effects of the Invention) As described in detail above, the present invention is directed to a cylinder of a tandem type master cylinder in which a pair of pistons are slidably inserted, and a pin protruding in the cylinder in the axial direction of the cylinder. Is connected to a hydraulic pressure control valve whose movement is released by moving to a cylinder, a cylindrical member with a long hole in the axial direction is provided at one end of the piston, and a pin protruding in the cylinder is provided with a long hole in the cylinder member. When the piston is displaced by a predetermined amount or more, the end portion of the elongated hole of the tubular member comes into contact with the pin to move the pin and release the operation of the hydraulic control valve. Further, since the pin protruding in the cylinder is inserted into the elongated hole of the cylindrical member, the outer diameter of the cylindrical member can be set to be substantially equal to the inner diameter of the master cylinder. As a result, sufficient hydraulic pressure can be secured in the brake system for the rear wheels when the brake system for the front wheels fails. Further, since the outer diameter of the tubular member can be set to be larger than that of the conventional one, there is an excellent effect that the degree of freedom in setting the size of the return spring or the like housed in the tubular member can be increased.

[Brief description of drawings]

 FIG. 1 is a vertical sectional view of an embodiment of the present invention, FIG. 2 is an enlarged horizontal sectional view of a tubular member of the apparatus of FIG. 1, and FIG. 3 is a vertical sectional view of a conventional master cylinder. . 15 …… master cylinder body 16 …… primary piston 17 …… secondary piston 20 …… hydraulic pressure control valve 23 …… slider 23a …… pin 24 …… cylinder member 25 …… long hole

Claims (1)

(57) [Scope of utility model registration request] 1. A hydraulic pressure in which operation is canceled by moving a pin projecting in a cylinder of a tandem type master cylinder in which a pair of pistons are slidably inserted into the cylinder in the axial direction of the cylinder. A cylindrical member having a long hole bored in the axial direction connected to a control valve is provided at one end of the piston, and a pin protruding in the cylinder is inserted into the long hole of the cylindrical member. The master cylinder to be used.