JPS6216858B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic pressure booster that uses hydraulic pressure from a hydraulic pressure source to boost input and output the same.

This type of booster includes, for example,
As seen in Publication No. 13728, there is a piston that defines the inlet side liquid chamber and the outlet side liquid chamber in the main body and is integrated with the output shaft. Since the inner end of the main body is slidingly guided by the main body, it has the advantage of smooth sliding, but on the other hand, when the input shaft directly presses the output shaft as in the case of sudden operation, it acts on the piston. The drawback was that the output could not be obtained immediately due to the large resistance force.

In order to improve this point, recently, for example,
As seen in Publication No. 50-28189, it has been proposed that a free piston separate from the output shaft is used to define the inlet side liquid chamber and the discharge side liquid chamber. . However, in this case, the inner peripheral surface of the annular free piston is slidably fitted to the input shaft, and
Since the outer circumferential surface is fitted to the inner circumferential surface of the main body, it goes without saying that the dimensional relationship between the inner circumferential surface and the outer circumferential surface of the free piston must be extremely accurate. Both the outer circumferential surface of the shaft and the inner circumferential surface of the main body must be finished with high precision, which is extremely troublesome in manufacturing. Furthermore, since the inner end of the output shaft is not guided relative to the main body, it is likely to cause wobbling, which is undesirable for obtaining stable operation. Furthermore, since the free piston is large and heavy, it
After the input shaft directly presses the output shaft, when the free piston, which receives thrust with a slight time delay, contacts and presses the output shaft, a large impact generated at this contact occurs on the operating pedal ( This was transmitted to the brake pedal (normally the brake pedal), which was unfavorable in terms of pedal feel.

The present invention solves the above-mentioned problems at once by integrating a piston that defines an inlet-side liquid chamber and an outlet-side liquid chamber in the main body with an output shaft, thereby making the output shaft smooth. While ensuring sliding, a pressure receiving plate that does not slide on the main body but can freely slide on the input shaft can be seated and removed from the rear end surface of the piston-output shaft structure, and A relief passage formed in the output shaft structure that communicates the inlet-side liquid chamber and the outlet-side liquid chamber is opened and closed according to the separation and seating of the pressure receiving plate, so that the pressure receiving plate is pressed by the piston during sudden operation. The present invention is characterized in that the high-pressure liquid pressure in the liquid chamber on the outlet side is quickly released to the liquid chamber on the inlet side through the relief passage, thereby making it possible to obtain an output immediately.

Embodiments of the present invention will be described below with reference to the drawings. In the figure, 1 is a main body, and the main body 1 includes a cylinder 2 having a cylindrical shape with a bottom, and a guide that is slidably fitted into the open end of the cylinder 2 and is prevented from coming off outward by a retaining ring 3. The body 4 is configured like a closed container.

A piston 5 is slidably inserted into the main body 1, and the piston 5 divides the inside of the main body 1 into an inlet liquid chamber A located on the rear side (right side in the figure) and an outlet side located on the front side. A side liquid chamber B is defined. The main body 1 is formed with an inlet 6 that opens into the inlet side liquid chamber A and an outlet 7 that opens into the outlet side liquid chamber B.

A rear end portion of an output shaft 8 is integrated with the piston 5, and the output shaft 8, which extends forward, slidably passes through the guide body 4 and extends to the outside. This piston 5 has a stepped hole opened in its rear end face, which is a large diameter part 5a and a small diameter part 5b in order from the rear side to the front side, and the diameter of the small diameter part 5b is the same as the outer diameter of the output shaft 8. ing. The front end of an input shaft 9 disposed on the same axis as the output shaft 8 is slidably fitted into the small diameter portion 5b, and the rear end of the input shaft 9 slides on the rear wall of the main body 1. It extends freely through the shaft and extends to the outside.

Further, the piston 5 is formed with a communication passage 10 that communicates the interior of the large diameter portion 5a with the outlet side liquid chamber B, while the input shaft 9 is formed with a communication path 10 that communicates the interior of the large diameter portion 5a with the outlet side liquid chamber A and the large diameter portion 5a. A pressure control passage 11 having a throttling action is formed to communicate with the liquid chambers A and B, and the liquid chambers A and B are communicated with each other via these passages 10 and 11. In order to configure a variable throttle mechanism at the opening of the pressure control passage 11 into the large diameter portion 5a, the piston 5
An annular valve seat 12 is formed on the stepped rear end surfaces of both diameter portions 5a and 5b. The annular valve body 13, which is seated on and off the valve seat 12, is preferably made of a flexible plate material, and its outer circumferential surface is slidably guided by the inner circumferential surface of the large diameter portion 5a of the piston 5. Rearward displacement beyond a predetermined value with respect to the input shaft 9 is regulated by a stopper 9a protruding from the input shaft 9.

Further, an annular pressure receiving plate 14 is slidably fitted to the input shaft 9, and the pressure receiving plate 14 can be moved to and from the rear end surface of the piston 5, that is, the open end surface of the large diameter portion 5a. This pressure receiving plate 14 is loosely fitted into the main body 1, so when the pressure receiving plate 14 is separated from the rear end surface of the piston 5, both liquid chambers A
and B are inside the passage 10, the large diameter portion 5a, and both elements 5.
and 14 through the gap. In other words, the passage 10 and the space within the large diameter portion 5a are the liquid chamber B on the outlet side during sudden operation, as will be described later.
It constitutes a relief passage for releasing the liquid pressure of 1 to the inlet side liquid chamber A, and also serves as a passage for communicating between both liquid chambers A and B via the variable throttle part mentioned above. Furthermore, it also serves as a part of a bypass passage, which will be described later.

The pressure receiving plate 14 is normally urged forward by a spring 15 so as to be seated on the rear end surface of the piston 5, and the flange portion 14a formed on the inner peripheral edge of the pressure receiving plate 14 comes into contact with the stopper 9a, so that the pressure receiving plate 14 is pressed against the input shaft 9. It is regulated so that it does not move forward beyond a predetermined level. A passage 16 opening in the large diameter portion 5a and extending in the radial direction is formed in the flange portion 14a, while
An annular cutout groove 17 is formed on the outer circumferential surface of the input shaft 9 in correspondence with the passage 16 . Both elements 16
and 17 constitute a bypass passage that communicates or blocks the inlet side liquid chamber A with the inside of the large diameter portion 5a, that is, the outlet side liquid chamber B, according to the relative displacement of the input shaft 9 with respect to the pressure receiving plate 14. ing. In other words, the pressure receiving plate 14 and the input shaft 9 constitute a spool valve that bypasses the variable restrictor and communicates and shuts off the liquid chambers A and B.

In the figure, reference numeral 18 denotes a return spring that is inserted between the guide body 4 and the piston 5 and urges the structure of the piston 5 and the output shaft 8 (hereinafter simply referred to as the structure 5 and 8) in the rear direction. 19 is a spring with a weak spring force that urges the input shaft 9 rearward, and 20 is a spring with a weak spring force that urges the valve body 13 rearward.

Next, the operation of the above-mentioned component device will be explained.
When used as a brake booster for automobiles,
For example, a pump 21 is connected to the inlet 6 and a power steering 2 is connected to the outlet 7.
and 22 are connected via a tank 23 as a hydraulic pressure source. Further, the input shaft 9 is connected to a brake pedal 25 via a plunger 24, and the output shaft 8 is connected to a brake pedal 25 via a plunger 24.
is connected to the piston 27 of the master cylinder 26.

First, when the brake is not activated, no input is applied to the input shaft 9, and the illustrated state is maintained. That is,
Both shafts 8, 9 and the pressure receiving plate 14 are in the most retracted position (the pressure receiving plate 14 is prevented from moving rearward beyond a predetermined amount by coming into contact with the rear wall of the main body 1), and the pressure receiving plate 14 is seated on the piston 5 to cut off the communication between the liquid chambers A and B through the relief passage, and to connect both the liquid chambers A through the passage passing through the variable throttle section and the bypass passage bypassing the same.
and B are in communication. Therefore, pump 2
The pressure oil that is force-fed from the tank 23 to the inlet side liquid chamber A directly reaches the inlet side liquid chamber B, and then returns to the tank 23 from the outlet 7 through the power steering 22. Since the bypass passage does not have a throttling action, both liquid chambers A and B have the same pressure and maintain the state shown in the drawing.

Now, when the driver depresses the brake pedal 25 and applies a forward input to the input shaft 9, only the input shaft 9 has weak springs 19, 20 at the initial stage of operation.
The bypass passage is closed (the communication between the notch groove 17 and the passage 16 is cut off). When this bypass passage is closed, the passage 11
A pressure difference is created between both liquid chambers A and B due to the throttling action of Thrust is generated and the two move forward together. As a result, the output shaft 8 presses the piston 27 of the master cylinder 26, and the brake is applied in a boosted state. At the initial stage of operation of the input shaft 9, the gap between the valve seat 12 and the valve body 13 is still large and there is no throttling effect in this area, so that both
The pressures in the valve chamber C formed between the valves 2 and 13 and the outlet side liquid chamber B are approximately equal, so that no reaction force against the output of the output shaft 8 is generated on the input shaft 9.

When the brake pedal 25 is further depressed, the valve body 13
As the valve comes closer to the valve seat 12, a throttling action occurs between the two, and the pressure difference between both liquid chambers A and B increases, and the pressure difference also increases between the valve chamber C and the outlet side liquid chamber B. occurs, and the output of the output shaft 8 also increases accordingly. That is, the sum of the forward thrust of the piston 5 and the pressure receiving plate 14 and the forward thrust due to the pressure difference between the chambers B and C is transmitted to the output shaft 8 as an output. At this time, the magnitude of the pressure within the valve chamber C is transmitted as a reaction force from the stopper 9a to the input shaft 9 via the valve body 13, and this reaction force provides pedal feeling.

When the depression force on the brake pedal 25 is released, the return spring 18 returns to the illustrated state.

Here, when the brake pedal 25 is suddenly depressed, at the initial stage, the input shaft 9 directly presses the output shaft 8 (the output shaft 8 is formed with a stepped portion 8a against which the front end surface of the input shaft 9 comes into contact). ), the piston 5 also moves together with the forward movement of the output shaft 8. As the piston 5 moves forward, the increased pressure generated in the outlet side liquid chamber B acts on the pressure receiving plate 14, and the pressure receiving plate 14 is separated from the rear end surface of the piston 5. This pressurized oil flows through the passage 10, the large diameter portion, 5a, and both elements 5.
and 14, and is released to the inlet side liquid chamber A, and the components 5 and 8 are smoothly moved forward without being subjected to a large resistance force, and as a result, an output is immediately obtained. Thereafter, with a slight time delay, the pressure receiving plate 14 is relatively slowly seated on the rear end surface of the piston 5, cutting off communication between the two liquid chambers A and B.
After this communication is cut off, the forward thrust generated in the piston 5 and the pressure receiving plate 14 and the forward thrust due to the pressure difference between the chambers B and C are similar to the normal braking described above. It is transmitted to the output shaft 8, and the brake is applied in a boosted state.

In the embodiment, in order to obtain a so-called jump-up characteristic, the pressure control passage has a throttling effect, and a bypass passage 17 is provided which bypasses the pressure control passage and the variable throttling mechanism and communicates both liquid chambers A and B. , 16, 5a, and 10 are shown, but if jump-up characteristics are not required, this bypass passage may be eliminated and the pressure control passage may not have a throttling effect. In addition, the passage 10 of the piston 5, the large diameter portion 5a
not only acts as a relief passage, but also connects both liquid chambers A through the variable throttle mechanism and the pressure control passage 11.
Although a part of the passage communicating with B and a part of the bypass passage are also used, these passages may be constructed completely separately and independently.

As is clear from the above description, the present invention has the following various effects.

As a result of the inner end of the output shaft being slidably guided to the main body via the piston, the output shaft is slidably guided smoothly with respect to the main body without rattling, and stable operation is obtained.

In the case of sudden operation, the increased pressure generated in the liquid chamber on the outlet side is released to the liquid chamber on the inlet side, so that when an input is applied, an output is immediately obtained, resulting in excellent responsiveness. This ensures safety during sudden braking when used in a brake device.

The above pressure increase release is performed by separating the pressure receiving plate acting as a valve body from the rear end surface of the piston acting as a valve seat. In other words, the piston and the pressure receiving plate
This constitutes a check valve for the relief passage that communicates between the piston and B, but when actuated suddenly, the pressure receiving plate immediately separates from the piston to open the relief passage, so the above response is extremely good. .

The inner circumferential surface of the pressure receiving plate slides on the input shaft, but the outer circumferential surface does not slide on the inner circumferential surface of the main body, so high precision is not required for its finishing.

The pressure receiving plate itself does not need to directly define both liquid chambers A and B, and can be made lightweight enough to receive thrust. The impact when separated from the end surface and again abuts against the rear end surface is small, which is favorable in terms of pedal feel. Also,
The fact that this impact is small is also favorable in terms of improving durability.

[Brief explanation of the drawing]

The figure is a sectional view showing one embodiment of the present invention. 1...Main body, 5...Piston, 6...Inflow port,
7... Outlet, 8... Output shaft, 9... Input shaft, 1
1... Pressure control passage, 12... Valve seat (variable throttle mechanism), 13... Valve body (variable throttle mechanism), 14...
Pressure receiving plate, 10... Communication passage (relief passage), 5a...
Large diameter part (relief passage), A...Inlet side liquid chamber, B...
...Outlet side liquid chamber.

Claims (1)

[Scope of Claims] 1. A main body configured in the shape of a sealed container, and a main body that is slidably inserted into the main body and is divided into an outflow port-side liquid chamber and an inflow port-side liquid chamber in the front-rear direction. an output shaft that integrally extends forward from the piston, slidably passes through the main body, and extends to the outside; an input shaft that is slidably inserted into the rear end of the piston-output shaft structure and capable of pressing the structure, and a communication formed on the input shaft so as to communicate between the two liquid chambers. a variable throttle mechanism provided at the outlet side opening of the communication path and controlled by the input shaft; a relief path formed in the piston-output shaft structure and communicating the two liquid chambers; The outer circumferential surface is loosely fitted to the inner circumferential surface of the main body, and the inner circumferential surface is slidably fitted to the outer circumferential surface of the input shaft. A hydraulic pressure booster comprising: a pressure receiving plate that opens and closes a relief passage; and an inlet opening to the inlet side liquid chamber and an outlet opening to the outlet side liquid chamber, each formed in the main body.