JPS5921092Y2 - hydraulic master cylinder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic master cylinder, and more particularly to a hydraulic master cylinder for a vehicle brake system.

The invention particularly relates to variable ratio mask cylinders of the type that utilize a stepped piston or piston assembly that can slide within a stepped bore to provide either a large piston area or a small piston area.

In this type of mask cylinder, as described in British Patent No. 1,372,618, when moving the mask cylinder screw for braking, a large piston area is initially used to reduce the spacing between the brakes, resulting in a lower A large amount of hydraulic fluid is delivered to the brake cylinder at pressure, and then a small piston area is used to deliver a small amount of hydraulic fluid at high pressure to provide a strong braking force.

In order to perform such a two-stage braking action, a stepped piston is used in the mask cylinder piston, and the large diameter part of the stepped piston is placed facing the pressurizing chamber that communicates with the brake cylinder, and the large diameter part of the stepped piston is placed behind the large diameter part. A control chamber whose volume increases as the piston moves forward is provided between the small diameter portion of the piston and the inner surface of the cylinder.

The control chamber has passages communicating with the pressurization chamber and the hydraulic fluid tank, which passages are closed in sequence by a first check valve arrangement and a second check valve arrangement when the piston begins to move in the braking direction. These check valve devices are configured to only allow communication from the control chamber to the pressurizing chamber and from the tank to the control chamber.

Additionally, between the control chamber and the pressurizing chamber, there is a regulating valve that connects the compartments intermittently when the pressure in the pressurizing chamber exceeds a predetermined value, and completely connects the compartments when the pressurizing chamber reaches an even higher predetermined pressure. is provided.

In this way, before braking, the pressurized chamber communicates with the hydraulic fluid tank and is maintained at approximately atmospheric pressure, but when the piston is moved in the braking direction, the first check valve device and the second check valve device are in the closed position. As the piston moves forward, the volume of the pressurized chamber decreases in a sealed state, increasing the pressure.

At the same time, the pressure in the sealed control chamber increases as the piston moves forward, so the pressure tends to decrease, but the second check valve opens and hydraulic fluid flows into the hydraulic fluid tank, keeping it at almost atmospheric pressure. Ru.

Therefore, the entire area of the large-diameter portion of the piston with membrane removal acts as an effective piston area, supplying low-pressure hydraulic fluid to the brake cylinder at a high speed.

Next, when the pressure in the pressurizing chamber reaches a first predetermined value, the regulating valve opens and the hydraulic fluid flows back from the pressurizing chamber to the control chamber.

As a result, the pressure in the control chamber increases slightly and the regulating valve closes again, but when the pressure in the pressurizing chamber increases further, the regulating valve opens again.

In this way, the regulating valve gradually increases the pressure in the control chamber by repeatedly opening and closing, and when the pressure in the pressurizing chamber reaches a second high predetermined value, the pressure in the control chamber becomes equal to that of the pressurizing chamber, and the regulating valve opens posttympanically. It is kept as it is.

Therefore, of the hydraulic fluid in the pressurizing chamber that is pushed out by the forward movement of the piston, the amount of hydraulic fluid that is pushed out by the area difference between the large diameter part and the small diameter part of the piston will flow back into the control chamber, so it will not be pressurized. The effective area of the piston that contributes to pressure is equal to the area of the small diameter portion, providing a strong braking force.

In the above configuration, the regulator valve provides the effect of switching from a large piston effective area to a small piston effective area, and also provides the effect of mitigating sudden changes in braking force during that time.However, conventional regulator valves have a pressure receiving area is small and the spring holding it in the closed position is of a weak and precise spring load construction.

Therefore, since it operates with a very weak force, it has the disadvantage of being too sensitive to the dynamic pressure caused by the flow of a large amount of hydraulic fluid during sudden braking.

The object of the present invention is to provide a control valve with a structure that has a large pressure-receiving area and can use a strong spring in order to eliminate this drawback.

According to the invention, a hydraulic master cylinder for a hydraulic brake device has a stepped piston that can slide in a stepped hole, a supply port for connection to a hydraulic fluid tank, and a connection to a brake actuation device. a pressurized chamber connected to the supply port and the outlet, the pressurized chamber is configured to cut off communication between the pressurized chamber and the supply port when the stepped piston moves in the braking direction; A pressurized chamber is configured to reduce the volume of the piston and generate braking pressure at the outlet, and a control chamber is connected to the supply port, and when the stepped piston moves in the braking direction, the pressurized chamber is connected to the control chamber. A control chamber configured to cut off communication with the supply port and increase the volume of the control chamber, a first check valve device that communicates the control chamber and the pressurizing chamber, and the supply port and the control chamber. and a stepped plunger slidable in a hole in the stepped piston, the action of the pressure in the pressurized chamber being applied to a relatively large piston area of the plunger. biasing the plunger in one direction, as opposed to the action of the preload spring and the pressure in the control chamber applied to the relatively small piston area of the plunger to bias the plunger in the same direction as the preload spring. a control valve comprising a plunger, the control valve plunger having an axial hole, which hole is normally closed by a closing member, and the closing member moves in the one direction together with the plunger. opened by restricting the movement of the members;
The hydraulic fluid may flow from the pressurization chamber through the axial hole into the control chamber, and the regulator valve provides controlled communication from the pressurization chamber to the control chamber. Until then, the pressure in the control chamber remains at the supply port pressure due to communication by the second check valve device, and then the pressure in the control chamber increases at a faster speed as the pressure in the pressurizing chamber increases. , are arranged so as to be equal to the pressure inside the pressurizing chamber.

Other features of the present invention will become apparent from the embodiments described below with reference to the accompanying drawings.

The illustrated mask cylinder 11 has a stepped bore within which a stepped main piston assembly can slide, the main piston assembly having an annular piston 12 and a stepped main piston assembly within the annular piston. and an inner piston assembly 20 slidable within an axial bore of the piston assembly.

The inner piston assembly 20 includes an inner piston 13 and a stepped plunger 31.

Said annular piston 12 has a stepped cylindrical surface, the small diameter portion of which is able to slide within a first annular cup seal 14 and a second annular cup seal 15 .

The annular piston 12 is connected via a tubular plunger 16 to
The inner piston assembly 20 is adapted to receive thrust from the piston or diaphragm of the vacuum servo unit, while the inner piston assembly 20 receives thrust from the servo valve member through an extension of the servo valve member 17, which servo valve member 17 is adapted to receive thrust from the servo valve member. connected to a rod.

The servo is disclosed in Japanese Patent Application No. 52-57516 (Japanese Patent Application No. 52-57516).
It is of the type shown in FIG. 1 of Japanese Patent No. 140773).

A main pressurized chamber 18 within the mask cylinder 11 is formed between a main piston assembly and a second piston 19 that is slidable within the mask cylinder body.

An annular control chamber 21 is formed between the third annular cup-shaped seal 22 that seals the large diameter portion of the annular piston 12 and the first annular cup-shaped seal 14 .

The return port 23 connects the main pressurizing chamber 18 to the control chamber 21 when the annular piston 12 is retracted relative to the stop pin 24 .

This return opening 23 opens into a counterbore closed by a plug 25, which has a passageway (not shown) communicating with the control chamber 21 located in the same diametric plane as the pin 24. ing.

Another return opening 26 connects said control chamber 21 to another annular chamber 27 via a port 28 and an axial bore of said annular piston 12 when the annular piston is in the retracted position.

Said chamber 27 opens into a supply port 29 in the mask cylinder body and is adapted to be connected to a reservoir of hydraulic brake fluid.

The regulator valve assembly includes a stepped plunger 31 having a large diameter portion that slides within an axial bore in the annular piston 12 and a small diameter portion that slides within an axial blind bore in the piston 13. It has

A chamber 33 is formed between the small diameter end of the plunger 31 and the blind end of the bore in the piston 13.

The control valve assembly still has a valve closing member in the form of a ball 32 which is normally pressed against an annular seat at the open end of the axially stepped bore in the plunger 31 by a light compression spring 30. It's sitting on top.

The pin 34 is adapted to slide within the bore of the plunger 31 and impinge on a diametrical cross pin 35 carried by the piston 13.

The preloaded coil spring 36 springs the plunger 31 away from the piston 13 towards a localized position defined by the engagement of the cross pin 35 with the diametrical bore of the plunger 31, with the cross pin 35 assembling the plunger 31 and piston 13. It is designed to be held as a three-dimensional object.

The annular cup-shaped seal 22 functions as a first check valve, and even when the annular piston 12 advances in the braking direction toward the second piston 19 and the return port 23 is covered and closed by the seal 22, the control chamber is closed. When the pressure in the pressure chamber 21 is greater than the pressure in the pressure chamber 18, communication from the control chamber 21 to the pressure chamber 18 is allowed.

This action is also supplemented by the ball 32 which leaves the valve seat of the plunger 31 when the pressure in the control chamber 21 is higher than the pressure in the pressurized chamber.

Similarly, seal 14 acts as a second check valve allowing fluid to flow from the tank into control chamber 21 .

An outlet 37 in the mask cylinder body is connected to one set of brakes of the split brake system, and another outlet 38 is adapted to be connected to another set of brakes.

To perform braking, the inner piston assembly 20 is pushed toward the second screw I/N 19, and then the annular piston 12 is immediately moved so that the seal 22 closes off the return port 23 and opens the main pressurized chamber. 18 and the control room 21 are blocked.

If the annular piston 12 moves a little further, the seal 1
4 shields the port 26 and prevents the control chamber 21 from communicating with the tank through the port 29.

A braking pressure is thus created in the main pressure chamber 18 and fluid is forced from the outlet 37 to the brake by a piston area equal to the area defined by the outer diameter of the seal 22.

The seal 14 removes water from the tank when the volume of the control chamber 21 increases with the braking movement of the annular piston 12.
Allows flow to 1.

The increased pressure in the main pressure chamber 18 acts on the large diameter portion of the regulator plunger 31 and generates a force that overcomes the preload of the spring 36, which is supplemented by the small force of the force spring 30. Ru.

When a considerable pressure is generated in the main pressurizing chamber 18, the regulator plunger 31 moves against the load of the spring 36 until the ball 32 contacts the pin 34.

In this state, the force that moves the regulating valve plunger 31 against the spring 36 is a force generated by the pressure acting on the annular area of the plunger 31 outside the diameter portion of the contact seat with the ball 32, and 30 (the force of this spring is acted upon by the reaction of the pin 34).

Therefore, the pressure in the main pressurizing chamber 18 is reduced by the regulator plunger 3.
1 is raised until it causes it to move further away from the ball 32 against the load of the spring 36.

This allows a certain amount of fluid to flow from the main pressurization chamber 18 to the control chamber 2.
1.

At this time, the effective piston area for expelling fluid from the first chamber 18 through the port 37 to the brake is the area corresponding to the inner diameter of the seal 14.

This is because the pressure within the control chamber 21 increases to a limit value that prevents fluid from exiting the tank through the seal 14.

The limit increase in pressure in the control chamber 21 is controlled by the control valve plunger 31.
ball 3 by spring 36
Helps the re-touching of 2.

However, due to the braking movement of the annular piston 12, the first
If the pressure in chamber 18 increases further, valve plunger 31
again moves against the spring 36 and an even larger amount of fluid flows into the control chamber 21, which increases the pressure within the control chamber 21 and again assists the action of the spring 36 to touch the ball 32 again. Have them sit down.

When the pressure in the first pressurizing chamber 18 increases, the ball 32 continues to move away from and touch the valve seat, and at the same time the pressure in the control chamber 21 increases due to the piston area of the large diameter portion and the small diameter portion of the valve plunger 31. The pressure rises at a faster rate according to the ratio until it equalizes the pressure in the pressurized chamber 18, and the ball 32 remains away from the valve seat.

Since the large diameter portion of the plunger 31 and the cross-sectional area of the piston 13 are equal, the thrust force on the servo valve member 17 is always proportional to the braking pressure generated in the first chamber 18.

The washer 39 contacts the second piston 19 in the event of a failure of the hydraulic line to the brake actuation device delivering fluid through the port 37 .

This second piston 19 transmits pressure from the first chamber 18 to the second chamber 41 and is adapted to actuate the other brake by way of the port 38 in the usual manner in skewer-type master cylinders.

The rubber washer 42 is disclosed in Japanese Patent Application No. 52-57516.
In the event of such a failure, the drive force applied through the inner piston assembly 20 and the driving force applied through the annular piston 12 act as a reaction mechanism in the event of such a failure, as illustrated by FIG. It is designed to distribute servo power.

[Brief explanation of drawings]

The accompanying drawing is a cross-sectional view of an embodiment of the hydraulic master cylinder according to the present invention, showing a state in which the mask cylinder is operated by a vacuum servo unit. In the figure, 11 is a mask cylinder, 12 is a circular screw)
13 is an inner piston, 14 is a first cup-shaped seal,
15 is a second cup-shaped seal, 16 is an annular plunger, 1
7 is a servo valve member, 18 is a main pressurizing chamber, 19 is a second piston, 20 is an inner piston assembly, 21 is an annular control chamber, 2
2 is a third cup-shaped seal, 23 is a return port, 24 is a stop pin, 25 is a plug, 26 is a return port, 27 is an annular chamber, 28
29 is a supply port, 30 is a compression spring, 31 is a stepped plunger, 32 is a ball, 33 is a chamber, 34 is a pin, 35
is a cross pin, 36 is a coil spring, 37.38 is an outlet,
39 is a washer, 41 is a second chamber, and 42 is a rubber washer.

Claims (5)

[Scope of utility model registration request] (1) a stepped piston slidable in a stepped hole; a supply port for connection to a hydraulic fluid tank; an outlet for connection to a brake actuation device; a pressurizing chamber, and when the stepped piston moves in a braking direction, communication between the pressurizing chamber and the supply port is cut off, the volume of the pressurizing chamber is reduced, and braking pressure is generated at the outlet. and a control chamber connected to the supply port, and when the stepped piston moves in a braking direction, communication between the control chamber and the supply port is cut off,
and a control chamber configured to increase the volume of the control chamber, a first check valve device that communicates the control chamber and the pressurizing chamber, and a second check valve device that communicates the supply port and the control chamber. and a stepped plunger slidable in a hole in the stepped piston, the preload spring and the preload being compressed by the action of the pressure in the pressurized chamber applied to the relatively large piston area of the plunger. a regulating valve consisting of a plunger biased in one direction against the action of the pressure in the control chamber applied to a relatively small piston area of the plunger to bias the plunger in the same direction as the load spring; In the hydraulic mask cylinder for a pressure brake device, the adjusting valve plunger has an axial hole, and the hole is normally closed by a closing member, and the closing member moves in the one direction together with the plunger. is opened by restricting the movement of the pressurized chamber to allow the hydraulic fluid to flow from the pressurized chamber through the axial hole into the control chamber; The pressure in the control chamber remains at the supply port pressure due to communication by the second check valve device, and then the pressure in the control chamber reaches the pressure in the pressurizing chamber. 1. A mask cylinder that is arranged so that as the pressure increases, the pressure rises at a faster rate and becomes equal to the pressure inside the pressurizing chamber. (2) In the mask cylinder according to item 1, the movement of the closing member in the one direction together with the plunger is limited by a pin that can slide in the plunger in the axial direction. mask cylinder. (3) A mask cylinder according to claim 2, wherein the pin is capable of abutting a diametrical cross pin carried by the stepped piston. (4) The master cylinder according to any one of items 1 to 3 above, wherein the closing portion is a ball. (5) In the master cylinder according to any one of items 1 to 4, the stepped piston is an annular piston having an axial hole, and the inner piston assembly is inserted into the axial hole. is slidable, the inner piston assembly having a regulator plunger and an inner piston, said plunger and inner piston being held together for limited relative axial movement. a preload spring is actuated between the plunger and an inner piston, the annular piston receives thrust from a servo piston or a diaphragm, and the inner piston is connected to an input pushrod of the servo. A mask cylinder that receives thrust from a servo valve member.