JPS5923648Y2 - Tandem master cylinder with hydraulic control valve - Google Patents

Description

[Detailed description of the invention] The present invention controls the brake fluid pressure transmitted to the tandem master cylinder of an automobile brake system, particularly the rear wheel brake, to a lower value than the brake fluid pressure transmitted to the front wheel brake. The present invention relates to a tandem master cylinder with a hydraulic pressure control valve.

Conventionally, in a brake system in which each hydraulic pressure generation chamber of a tandem master cylinder is connected to the front wheel brake and the rear wheel brake, when a hydraulic pressure control valve is installed to control the brake fluid pressure of the rear wheel brake, the hydraulic pressure generation chambers of the tandem master cylinder are connected to the front wheel brake and the rear wheel brake. This was installed in the middle of each brake pipe leading to the brake.

However, in this case, it was necessary to install piping for two hydraulic control valves, and these control valves usually needed to be installed in the engine compartment, making the piping and installation work very complicated. .

Therefore, a hole for mounting a hydraulic pressure control valve is provided on the discharge port side of each hydraulic pressure generating chamber of the tandem master cylinder, the assembled hydraulic pressure control valve is placed in the hole, and the hydraulic control valve assembly is installed. By fixing it to the tandem master cylinder with a joint member that has a pipe connection port to the rear wheel brake,
A tandem master cylinder with a hydraulic control valve is proposed, which eliminates the piping and installation work between the master cylinder and the hydraulic control valve, which was previously required. If a structure is adopted to improve responsiveness during hydraulic pressure control, if a failure occurs in the hydraulic pressure control valve assembly, brake fluid may leak out from that part.

When this happens, the rear wheels are braked or no brakes are applied, causing a problem in which safe braking action cannot be obtained.

The present invention has been made in view of the above problems, and aims to provide a tandem master cylinder with hydraulic control valves that improves not only responsiveness but also safety. a hydraulic pressure generating chamber, a pair of holes provided in the discharge boss portion of the master cylinder body and each communicating with the hydraulic pressure generating chamber and having a connection port to the front wheel brake, and a hydraulic pressure generating chamber for the rear wheel brake device. a hydraulic control valve assembly having a control valve body which is removably fitted into each of the pair of holes and has a flange portion formed at one end in order to control the hydraulic pressure to a lower value than the hydraulic pressure to the front wheel brake; , a sealing member attached to the outer periphery of the control valve body on the side of the hydraulic pressure generation chamber and in close contact with the hole, and holding the flange portion under pressure between a shoulder portion formed in the hole and the flange portion; a stepped joint member provided on the control valve body, the joint member being screwed into the openings of the pair of holes to form a seal with the shoulder portion, and having a connection port to each rear wheel brake; A step that is slidably inserted into the cylinder hole and partitions an inlet chamber communicating with the hydraulic pressure generation chamber on the small diameter side and an outlet chamber communicating with the connection port to the rear wheel brake on the large diameter side. A variable volume air chamber is formed in the cylinder hole facing a stepped portion of the piston that borders a small diameter portion and a large diameter portion, and an air chamber with a variable volume is formed in the cylinder hole between the hole and the control valve body, and the sealing member and the It communicates with a second air chamber formed in close contact with the seal portion.

By doing this, the air chamber in the control valve body is substantially enlarged, and even if the stepped piston moves during hydraulic pressure control and the volume of the air chamber changes, the pressure in the air chamber will not increase. The degree of this can be made extremely small.

As a result, even when the stepped piston moves and the volume of the air chamber changes depending only on the hydraulic pressure acting on the inlet chamber side and the outlet chamber side, the degree of increase in the pressure of the air is extremely high. Can be made smaller.

As a result, the stepped piston can be moved only in accordance with the hydraulic pressure acting on the inlet chamber side and the outlet chamber side, and responsiveness during the hydraulic pressure control can be improved.

Furthermore, since the second air chamber is sealed, if a failure of the hydraulic control valve assembly occurs in which brake fluid leaks into the air chamber from the inlet chamber or the outlet chamber, the second air chamber is sealed. Even when the chamber and the second air chamber are filled with liquid, the liquid does not flow out to the outside, so the hydraulic pressure generated in the hydraulic pressure generating chamber is transmitted to the rear wheel brake.

Therefore, it is possible to prevent the rear wheels from not being braked, and it is possible to improve safety in the event of a failure of the hydraulic control valve assembly.

As described above, according to the present invention, it is possible to obtain a hydraulic control valve tandem master cylinder that has improved not only responsiveness but also safety.

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

Reference numeral 1 denotes a main body of a tandem master cylinder, which is provided with a cylinder hole 2 extending in the axial direction and provided with two liquid tanks 3 and 4 at the upper part.

Inside the cylinder hole 2, there is a first piston 7 equipped with sealing materials 5 and 6, and a sealing material 8. The second pistons 11 equipped with 9.10 are slidably inserted, and the first hydraulic pressure generating chamber 12 is formed between the first piston 7 and the second piston 11, and the first hydraulic pressure generating chamber 12 is formed between the second piston 11 and the cylinder hole. A second hydraulic pressure generating chamber 22 is formed between the left closing wall 2a and the second hydraulic pressure generating chamber 22.

Reference numeral 13.14 denotes a liquid replenishment hole between the first pressureless chamber 15 defined between the sealing materials 5 and 6 on the outer periphery of the first piston 7 and the liquid tank 3 and the second piston 11. Liquid communication is established between the liquid tank 4 and the second pressureless chamber 16 defined between the seal members 9 and 10 on the outer periphery of the liquid tank 4 .

Reference numeral 17.18 denotes a liquid return hole which allows the first hydraulic pressure generation chamber 12 to return to the liquid tank 3 when the first and second pistons 7.11 are in the brake release position, that is, the position shown in the figure. ,
The second hydraulic pressure generating chambers 23 are communicated with the liquid tanks 4, respectively.

Reference numeral 19 denotes a first return spring, which is disposed with its tension set between the left end of the first piston 7 and the flange portion of the cup-shaped member 21 whose movement is restricted by the bolt 20. There is.

Reference numeral 23 denotes a second return spring whose tension is lower than that of the first return spring 19, and is provided between the spring receiver 24 provided on the left side of the second piston 11 and the closing wall 2a of the cylinder hole 2. The first piston 7 and the second piston 11 are pushed to the right.

25 is a stop plate which is prevented from being removed by a retaining ring 26;
The brake release position of the first piston 7 is determined.

Further, 27 is a stop bolt that prevents the second piston 11 from retreating excessively to the right.

Furthermore, the main body 1 has boss portions 30 and 31 extending downward in the drawing.
It has holes 32 and 33 that open downward.

The insides of these holes 32.33 communicate with the first and second hydraulic pressure generating chambers 12 and 22, respectively, via liquid passages 34.35.

36 is a communication port for connecting to the left front wheel brake 91 through the pipe 90, and 37 is a communication port for connecting to the right front wheel brake 93 through the pipe 92.

The hydraulic control valve assembly, generally designated 40.41, is
Threaded portions 42 and 43 are detachably inserted into the holes 32 and 33 and provided at the openings of the holes 32 and 33, respectively.
It is fixed by a joint member 44, 45 screwed onto.

46.47 is a connection port provided in the joint member 44.45, and is connected to the pipe 94 connected to the right rear wheel brake 95.
, and a pipe 96 connected to the left rear wheel brake 97
are connected to each.

The specific structure of the hydraulic control valve assemblies 40 and 41 and the attachment mechanism to the holes 32 and 33 in the master cylinder main body will be further described with reference to FIG.

Note that the structure of the hydraulic control valve assembly 40 and the mechanism for attaching it to the hole 32 are the same as that of the hydraulic control valve assembly 41 and the mechanism for attaching it to the hole 33, so FIG. Only the portion to which the hydraulic control valve assembly 40 is attached is shown.

Reference numeral 50 denotes a control valve body of the hydraulic control valve assembly 40, which has a stepped cylinder hole 51 inside, a flange portion 52 at its lower end, and a lower end surface 53 having a conical shape. This forms the seat surface when the pipe 94 is attached to the joint member 44.

Note that when sealing between the pipe 94 and the joint member 44 is performed at the lower end surface of the joint member 44, the lower end surface of the control valve main body 50 does not need to be conical.

54 is a passage for communicating the inside of the cylinder hole 51 with the connection port 46.

Reference numeral 55 denotes a stepped piston, which has a through hole 56 inside, is slidably inserted into the cylinder hole 51, and has an outlet chamber below the stepped piston 55 that communicates with the connection port 46 through a passage 54. It has the shape of 57.

58 is a sealing material attached to the large diameter portion 55a of the stepped piston 55; 59 is a sealing material supported by a receiving plate 60 that is in contact with the stepped portion of the cylinder hole 51; It is formed between the air chamber 62 on the outer periphery of the small diameter part and the outlet chamber 57, and between the air chamber 62 and the cylinder hole 51, and communicates with the first hydraulic pressure generating chamber 12 via the liquid passage 34. A liquid-tight seal is provided between the two and the inlet chamber 61 that communicate with each other.

63 is a lid plate that opens in the center, and includes the cylinder hole 51.
It is supported by a retaining ring 80 at the upper opening of.

Reference numeral 64 denotes a valve member for opening and closing the upper end of the through hole 56 of the stepped piston 55, and is guided and supported by the valve support member 65 and pressed downward by the valve spring 66.

Reference numeral 67 denotes a preload spring that presses the stepped piston 55 downward with a predetermined force. It is set up.

An annular recess 74 is provided on the outer periphery of the control valve body 50,
This recess 74 communicates with an air chamber 62 formed between the small diameter hole of the cylinder hole 51 and the outer periphery of the small diameter portion of the stepped piston 55 through the vent hole 73, A second air chamber is formed between the air chamber and the air chamber, thereby substantially enlarging the air chamber.

A sealing material 69 is attached to the outer periphery of the control valve main body 50 to provide a fluid-tight seal between the second air chamber 74 and the inlet chamber 61.

The flange portion 52 of the control valve body 50 is fixed by hydraulic pressure between a shoulder portion 70 provided in the hole 32 and an engagement surface 71 of the joint member 44 screwed onto the opening thread portion of the hole 32. and
A shoulder 70 seals between the hole 32 and the control valve body 50 , and an engagement surface 71 seals between the control valve body 50 and the joint member 44 .

Next, the operation of this embodiment will be explained.

When the brake pedal (not shown) is depressed to apply the brakes, the first piston 7 and the second piston 1
1 moves to the left, and the sealing materials 6 and 10 close to the liquid return hole 1.
7 and 18 are closed, and the first and second hydraulic pressure generating chambers 12 are closed.
Brake fluid pressure is generated at and 22, respectively.

These hydraulic pressures are transmitted into the holes 32 and 33 through the fluid passages 34 and 35, and the hydraulic pressure transmitted into the holes 32 is transmitted through the communication port 36 and piping 90 to the left front wheel brake 91. The hydraulic pressure is transmitted to the right rear wheel brake 95 through the hydraulic control valve assembly 40, the connection port 46, and the piping 94.
The hydraulic pressure transmitted to the hydraulic control valve assembly 41. Pass through the connection port 47 and piping 96 to the left rear wheel brake 9
7 and applies brakes to all wheels.

When the brake fluid pressure transmitted from the first and second fluid pressure generating chambers to the holes 32 and 33 reaches a predetermined pressure, the fluid pressure control valve assemblies 40 and 41 control the rear wheel brakes 95 and 97, respectively. begins to control the brake fluid pressure transmitted to the

The control action will be explained with reference to FIG.

The hydraulic pressure transmitted to the inlet chamber 61 by the liquid passage 34 acts on the effective area A1 of the small diameter portion of the stepped piston 55 and presses the stepped piston 55 downward in the figure.

At the same time, the hydraulic pressure transmitted from the inlet chamber 61 through the through hole 56 to the outlet chamber 57 is transferred to the large diameter portion 55 of the stepped piston 55.
It acts on the effective area A2 of a and presses the stepped piston 55 upward.

The brake fluid pressure transmitted to the inlet chamber increases and the fluid pressure that presses the stepped piston 55 upward, that is, the effective area A2
When the hydraulic pressure acting on the stepped piston 55 becomes greater than or equal to the sum of the hydraulic pressure that presses the stepped piston 55 downward, that is, the hydraulic pressure acting on the effective area A1 and the preset tension of the preload spring 67, the stepped piston 55 moves upward against the hydraulic pressure acting on the effective area A1 and the tension of the preload spring 67, and the upper end of the through hole 56 engages with the valve member 64, thereby establishing liquid communication between the inlet chamber 61 and the outlet chamber 57. shuts off and starts hydraulic control action.

When the hydraulic pressure transmitted to the inlet chamber 61 further increases, the stepped piston is pushed downward again by the increased hydraulic pressure, so that the upper end of the through hole 56 separates from the valve member 64, causing the hydraulic pressure in the population chamber 61 to increase. is transmitted to the outlet chamber 57.

However, since the increase in the hydraulic pressure in the outlet chamber 57 acts on the effective area A2, the increase in the hydraulic pressure in the outlet chamber 57 is greater than the increase in the hydraulic pressure in the inlet chamber 61 due to the increase in the large diameter part and the small diameter part of the stepped piston. When a predetermined ratio set by the effective area ratio is reached, the stepped piston 55 moves upwardly and the valve member 64 once again blocks fluid communication between the inlet chamber 61 and the outlet chamber 57.

That is, the hydraulic pressure in the outlet chamber 57 after the start of hydraulic pressure control is the sum of the force pushing the stepped piston 55 downward, that is, the tension of the preload spring 67, and the hydraulic pressure in the inlet chamber 61 acting on the area A1, and the stepped piston 55. Force pushing the piston 55 upward, that is, area A2
The liquid pressure in the outlet chamber 57 is controlled so as to maintain a balanced state.

Therefore, the hydraulic pressure increase gradient in the outlet chamber 57 after the control is started is reduced to A1/A2 of the hydraulic pressure increase gradient in the inlet chamber 61. brake fluid pressure is transmitted.

Further, the hydraulic control valve assembly 41 also includes the hydraulic control valve body 4 described above.
0, the brake fluid pressure whose increase rate is reduced to a predetermined ratio with respect to the right front wheel brake fluid pressure is transmitted to the left rear wheel brake 97.

Therefore, brake fluid pressure that is reduced by a predetermined ratio compared to the front wheel brakes 91.93 is transmitted to the rear wheel brakes 95.97.

When the hydraulic pressure to the rear brakes is controlled in this way,
As the stepped piston 55 moves, the volume of the air chamber 62 changes, but since the air chamber 62 communicates with the second air chamber 74 and is substantially larger, the degree of pressure increase in the air chamber changes. is extremely small, and the air in the air chamber 62 does not act to impede movement of the stepped piston.

Therefore, as described above, the stepped piston 55 can quickly move in response to the applied hydraulic pressure.

If a sealing failure occurs in the sealing material 58 or 59 that partitions the air chamber 62 of the hydraulic control valve assembly 40, the outlet chamber 57
Also, even if the brake leaks from the inlet chamber 61 into the air chamber 62, the air chamber 62 is in communication with the second air chamber 74, so even if there is a small amount of fluid leakage, the air chamber will be filled with fluid. Therefore, there is no risk that the upward movement of the stepped piston 55 will be blocked and the hydraulic control effect will be disabled.

Further, even if the sealing material 58 or 59 does not lose its sealing function and the air chamber 62, 74 and the outlet chamber 57 or the inlet chamber 61 are in communication, the air chamber 74 is sealed by the shoulder 70. There is no risk of brake fluid pressure leaking to the outside and causing no braking.

Now, the brake system connected to the second hydraulic pressure generation chamber 22,
For example, if the brake is applied while the piping 92 or 96 is damaged, the first and second pistons 7
and 11 move to the left.

Since no hydraulic pressure is generated in the second hydraulic pressure generation chamber 22, the first and second pistons 7 and 11 move until the left end of the second piston 11 abuts the blockage 2a of the cylinder hole. After that, brake fluid pressure is generated in the first fluid pressure generation chamber 12.

This hydraulic pressure is transmitted through the fluid passage 34 into the hole 32, through the communication port 36 and piping 90, and directly to the left front wheel brake 91, as well as through the fluid pressure control valve assembly 40 and the connection port 46.
, is transmitted to the right rear wheel brake 95 through the pipe 94,
Brakes are applied to the left front wheel and right rear wheel.

When the brake fluid pressure generated in the first fluid pressure generating chamber 12 reaches a predetermined value, the fluid pressure control valve assembly 40 starts its control action and transfers the fluid pressure to the rear wheel brake 95 to the front wheel brake 9.
1 to a predetermined ratio to prevent the rear wheels from locking.

Next, the removal and assembly operations of the hydraulic control valve assemblies 40 and 42 will be explained.

If a failure occurs in the hydraulic control valve assembly 40 or 41 and it is necessary to remove it, the hydraulic control valve assembly can be removed by removing the pipe 94 or 96 and then the coupling member 44 or 45. 40 or 41 can be easily taken out.

Furthermore, when the hydraulic control valve assembly is repaired or replaced with a new one and then assembled into the main cylinder body 1 of the master cylinder, it can be easily assembled by inserting it into the hole 32 or 33 and screwing the joint member. I can do it.

As is clear from the above explanation, the present invention not only simplifies assembly and removal of the hydraulic control valve and greatly simplifies piping work, but also greatly reduces the degree of pressure rise in the air chamber during hydraulic pressure control. Not only does it become smaller and improve responsiveness, but it also prevents brake fluid from leaking to the outside in the event of a hydraulic control valve failure.
This has the excellent effect of preventing the rear wheels from not braking and improving safety.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a tandem master cylinder showing an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of the part in which the hydraulic control valve of FIG. 1 is installed. 1...Body, 2...Cylinder hole, 7.
...First piston, 11... Second piston, 12... First hydraulic pressure generation chamber, 22...
...Second hydraulic pressure generation chamber, 32.33...hole, 3
6, 37... Communication port, 40.41...
Hydraulic pressure control valve assembly, 44, 45... joint member,
46.47... Connection port, 50... Control valve body, 52... Flange section, 55...
・Stepped piston, 62...Air chamber, 69...
...Sealing material, 70...Shoulder part, 74...
...Second air chamber.

Claims (1)

[Scope of utility model registration request] a pair of hydraulic pressure generating chambers formed in a master cylinder body; a pair of holes provided in a discharge boss portion of the master cylinder body, each communicating with the hydraulic pressure generating chamber and having a connection port to a front wheel brake; In order to control the hydraulic pressure to the rear wheel brake to a lower value than the hydraulic pressure to the front wheel brake, the control valve body is detachably fitted into each of the pair of holes and has a flange portion formed at one end. a hydraulic pressure control valve assembly; mounted on the outer periphery of the control valve body on the side of the hydraulic pressure generation chamber;
The openings of the pair of holes are configured to hold the flange portion under pressure between a sealing member that is in close contact with the hole and a shoulder portion formed in the hole, and to form a seal portion with the flange portion and the shoulder portion. and a joint member having a connection port to each rear wheel brake.The joint member is slidably inserted into a stepped cylinder hole provided in the control valve body, and the small-diameter side is provided with a joint member having a connection port to each rear wheel brake. A stepped piston that partitions an inlet chamber communicating with the pressure generation chamber and an outlet chamber communicating with the connection port to the rear wheel brake on the large diameter side, at a stepped portion that borders the small diameter portion and the large diameter portion. A variable volume air chamber formed in the cylinder hole facing each other communicates with a second air chamber closely formed between the hole and the control valve body by the sealing member and the sealing part. Tandem master cylinder with hydraulic control valve.