JPH04356269A - Reaction device of hydraulic pressure booster - Google Patents

Abstract

PURPOSE:To enable adjustment of the point of change from a large boosting ratio at the initial stage of inputs of a hydraulic booster to a smaller one. CONSTITUTION:A reaction piston 55 is normally held by the resilient force of a spring 57 in its advance position distant from the stopper 17A of an input shaft 17 and when hydraulic pressure is introduced into a power room 8 the reaction piston 55 is retreated relative to the input shaft 17 by the hydraulic pressure and made to abut on the stopper 17A. The spring 57 is resiliently interposed between the reaction piston 55 and an adjusting screw 58 threadably attached in the power piston 3 and when the adjusting screw 58 is rotated to vary the set load of the spring 57, hydraulic pressure at that moment when the reaction piston 55 abuts on the stopper 17A can be adjusted, whereby the point of change from a large boosting ratio at the initial stage of inputs to a smaller one can be adjusted.

Description

[Detailed description of the invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic booster used in a brake booster, and more particularly to a reaction device for a hydraulic booster equipped with a reaction piston.

[Prior Art] Conventionally, as a reaction force device for a hydraulic booster,
A power piston slidably provided in the housing, a power chamber formed at the rear of the power piston in the housing, an input shaft slidably penetrated through the housing from the rear side of the power piston, and the power piston. a control valve that is provided across the piston and the tip of the input shaft and supplies hydraulic pressure to the power chamber according to the input applied to the input shaft;
a reaction piston that is slidably provided on the outer periphery of the input shaft and is retracted with respect to the input shaft by hydraulic pressure in the power chamber and comes into contact with a stopper provided on the input shaft; the power piston and the reaction piston; There is a known spring equipped with a spring loaded between the stopper and a spring that holds the reaction piston at a forward position separated from the stopper by a predetermined repulsive force (Japanese Unexamined Patent Application Publication No. 2002-110002).
60871, JP-A-2-74456). In the hydraulic booster disclosed in the above publication, when the input shaft is moved forward, the control valve supplies hydraulic pressure corresponding to the input to the input shaft to the power chamber, thereby moving the power piston forward. A boosting effect will be exerted. At this time, the hydraulic pressure supplied to the power chamber acts on the input shaft to give a reaction force to the input shaft, and also acts on the reaction piston to force the reaction piston against the input shaft. This will cause them to retreat. Before the reaction piston comes into contact with the stopper provided on the input shaft, the hydraulic pressure acts only on the input shaft, which has a relatively small pressure-receiving area, so the output increases with a large boost ratio, and the reaction piston acts on the input shaft. When the two come into contact with the stopper provided on the shaft and become one, the pressure receiving area increases, so the output increases with a small boost ratio. A good operating feeling is ensured by such a large boost ratio at the initial stage of operation. In the past, various hydraulic boosters equipped with reaction pistons have been proposed (Japanese Unexamined Patent Publications No. 55-44095 and No. 56-90765), although the overall configurations are different.

[Problem to be Solved by the Invention] The hydraulic pressure at the moment when the reaction piston contacts the stopper provided on the input shaft is the point at which the boosting ratio changes from a large boosting ratio at the initial input to a small boosting ratio (Fig. 3). Point C) is determined by the set load of the spring, but in the past, the set load could not be changed, resulting in variations between hydraulic boosters and lack of versatility. Ta. In view of such circumstances, the present invention provides a reaction force device for a hydraulic pressure booster that allows the set load of the spring to be adjusted.

[Means for Solving the Problems] That is, the present invention provides a reaction force device for a conventional hydraulic pressure booster having the above-described configuration, in which an adjusting screw is screwed onto the power piston so as to be displaceable in the axial direction, and The spring is elastically mounted between the adjustment screw and the reaction piston.

[Operation] According to the above configuration, if the adjusting screw is rotated to displace the adjusting screw in the axial direction of the power piston,
Since the set load of the reaction piston can be adjusted by adjusting the elastic force of the spring, the change point from a large boost ratio at the initial input to a small boost ratio that occurs for each hydraulic booster (Fig. 3) can be eliminated. Further, since the above-mentioned change point can be changed depending on the vehicle type, versatility can be increased.

[Embodiment] The present invention will be described below with reference to the illustrated embodiment. In FIG. 1, a bore 2 is provided in a housing 1 of a hydraulic booster.
In this bore 2, a cylindrical part 3 is formed at the rear right side.
A power piston 3 having a shape A is slidably fitted therein. A push rod 4 provided at the left end of the power piston 3 is kept fluid-tight and slidably protrudes outside the housing 1, and its tip is interlocked with a piston of a master cylinder (not shown). The right end opening of the bore 2 is sealed by a plug 5 forming a part of the housing 1, and the plug 5 is integrally fixed to the housing 1 by a nut 6 screwed onto the housing 1. A power chamber 8 into which pressure oil is introduced is formed between the plug 5 and the power piston 3, and a spring 10 is installed in a low pressure chamber 9 formed on the opposite side of the power chamber 8 of the power piston 3. The resiliency of the spring 10 normally holds the power piston 3 in the non-operating position shown in the figure, where it abuts against the plug 5. The low pressure chamber 9 housing the spring 10 is communicated with a reservoir (not shown) via a passage 11 formed in the housing 1. An input shaft 17 connected to a brake pedal (not shown) is slidably passed through the plug 5 constituting a part of the housing 1, and the left end of the input shaft 17 and the cylindrical shape of the power piston 3 A control valve 18 is provided across the inside of the portion 3A. The control valve 18 is opened from the side opposite to the power chamber 8 by a first valve seat 20 formed on a plate 19 that is press-fitted into the cylindrical portion 3A of the power piston 3, and by the elastic force of a spring 21. A ball valve 22 seated on a seat 20, an annular pin 23 provided at the tip of the input shaft 17 to separate the ball valve 22 from the first valve seat 20, and a ring pin 23 formed at the tip of the annular pin 23. the second valve seat 2 on which the ball valve 22 is seated;
4. In the illustrated non-operating state, the ball valve 22
is seated on the first valve seat 20 due to the elastic force of the spring 21,
Communication between the power chamber 8 formed on the right side of the first valve seat 20 and the pressure chamber 29 formed on the left side is cut off. This pressure chamber 29 communicates with a pump (not shown) via a supply passage 30, and this pump always supplies pressurized oil at a predetermined pressure into the pressure chamber 29. The supply passage 30 includes a radial passage 31 formed in the power piston 3, an annular groove 32 formed on the outer peripheral surface of the power piston 3, a radial passage 33 formed in the housing 1, and a radial passage 33 formed in the housing 1. It consists of a conduit (not shown) that connects to the pump. Further, in the illustrated non-operating state, the second valve seat 24 at the tip of the annular pin 23 is separated from the ball valve 22 seated on the first valve seat 20, and in this state, the power chamber 8 is connected to the discharge passage 38. It communicates with the reservoir via. The discharge passage 38 includes a passage 39 formed in the shaft of the annular pin 23, a passage 41 formed in the shaft of a shim 40 interposed between the annular pin 23 and the input shaft 17, and a passage 41 formed in the shaft of the input shaft 17. A passage 42 formed in the plug 5 and a passage 4 formed in the plug 5.
3 and a passage 44 formed in the housing 1. By connecting this passage 44 to the above-mentioned passage 11, the discharge passage 38 is communicated with a reservoir (not shown). Further, the left end portion of the ball valve 22 constituting the control valve is slidably penetrated through the collar 48 while maintaining liquid tightness.
A balance chamber 49 is formed on the left side of the collar 48. This balance chamber 49 is communicated with the power chamber 8 through a communication passage 50 formed in the power piston 3 and a through hole 51 formed in the plate 19, and the pressure receiving area of the balance chamber 49 side of the ball valve 22 is The area is set larger than the area obtained by subtracting the area of the inner diameter of the second valve seat 24 from the area of the inner diameter of the first valve seat 20, that is, the pressure receiving area of the ball valve 22 on the power chamber 8 side. By setting the pressure receiving area in this way, when the input shaft 17 and the annular pin 23 are moved forward and the ball valve 22 is unseated from the first valve seat 20, thereby increasing the pressure in the power chamber 8, the annular The ball valve 22 seated on the second valve seat 22 of the pin 23 is separated from the second valve seat 24 to prevent liquid leakage. However, the plug 5 constituting a part of the housing 1 is provided with a cylindrical guide portion 5A protruding into the cylindrical portion 3A of the power piston 3 at its left end, and a reaction piston is attached to the guide portion 5A. 55 are slidably fitted, and the reaction piston 55 is slidably supported by the guide portion 5A. By slidably fitting the input shaft 17 to the shaft portion of the reaction piston 55, the input shaft 17 is slidably supported by the reaction piston 55 supported by the guide portion 5A. . A flange portion 55A extending radially outward is formed at the left end portion of the reaction piston 55, and a retainer 56 provided in the cylindrical portion 3A of the power piston 3 is connected to the outer peripheral portion of the flange portion 55A. A spring 57 is mounted between the pistons 57 and 57 to normally hold the reaction piston 55 in the non-operating position shown in the figure, where it abuts against the plate 19. In this state, the reaction piston 55 is located at a forward position relative to the input shaft 17 and is separated from the step-shaped stopper 17A provided on the input shaft 17. As will be described in detail later, when the acting force of the hydraulic pressure in the power chamber 8 applied to the reaction piston 55 exceeds the set load of the spring 57, the reaction piston 55
is moved back against the input shaft 17 against the spring 57 and comes into contact with the stopper 17A. As a result, before the reaction piston 55 comes into contact with the stopper 17A, the acting force of the hydraulic pressure in the power chamber 8 that has been applied to the reaction piston 55 is received by the power piston 3 via the spring 57 and the retainer 56. On the other hand, when the reaction force piston 55 comes into contact with the stopper 17A, the above acting force is transmitted to the input shaft 17 as a reaction force, so the force is doubled before and after the reaction force piston 55 comes into contact with the stopper 17A. The force ratio can be changed. The left end of the retainer 56 is
It is supported by being brought into contact with an adjusting screw 58 screwed into the opening of the cylindrical portion 3A of the power piston 3. Therefore, by rotating the adjusting screw 58, the elastic force of the spring 57 is adjusted. Thus, the set load of the reaction piston 55 can be adjusted. Further, the spring 57 and the retainer 56 are disposed within a gap formed between the outer periphery of the guide portion 5A and the inner periphery of the cylindrical portion 3A of the power piston 3. Therefore, in the illustrated non-operating state, the guide portion 5A, the sliding portion of the reaction piston 55 with respect to the guide portion 5A, the sliding portion of the input shaft 17 with respect to the reaction piston 55, and the urging of the reaction piston 55. The springs 57 are arranged in the radial direction while overlapping each other in the axial direction. As a result, the axial dimension of the hydraulic pressure booster is reduced compared to, for example, a conventional device in which the sliding portion of the reaction piston 55 and the sliding portion of the input shaft 17 are arranged in series in the axial direction. be able to. Next, to explain the loss stroke reduction mechanism of the input shaft 17 at the initial stage of operation, a stepped portion 17B is formed at the distal end of the input shaft 17, the diameter of which is reduced on the distal end side.
The tip side of the cylindrical stopper member 61 is inserted into the radially inner flange portion 61A formed at the right end of the cylindrical stopper member 61, and the flange portion 61A of the cylindrical stopper member 61 is inserted into the stepped portion 1.
It is in contact with 7B. The cylindrical stopper member 61 is fixed to the input shaft 17 by press-fitting the annular member 62 between the outer periphery of the input shaft 17 on the distal side of the stepped portion 17B and the inner periphery of the cylindrical stopper member 61. At the same time, it maintains liquid tightness between the two. As shown in FIG. 2, the left end of the cylindrical stopper member 61 is integrally formed with a stopper 61B that protrudes radially outward at a radially opposing position, and each stopper 61B is connected to the reaction force. piston 55
A diametrical slit 55 formed in the flange portion 55A of
It is made to protrude outward from the shaft portion of the reaction piston 55 via B. Then, the shim 40 and the annular pin 23 are sequentially inserted into the cylindrical stopper member 61, and the spring 63 is elastically loaded between the annular pin 23 and the plate 19. The stopper 61B is brought into contact with the left end surface of the guide portion 5A to restrict the input shaft 17 from retreating. On the other hand, the left end of the retainer 56 is extended to the right side adjacent to the stopper 61B, so that the retainer 56 can restrict the input shaft 17 from moving backward when the power piston 3 is moving backward. By the way, the radially outer side of the power chamber 8 formed in the bore 2 is kept liquid-tight by a seal member 66 provided on the outer periphery of the plug 5 and a seal member 67 provided on the outer periphery of the power piston 3. ing. On the other hand, the space between the radially inward side of the power chamber 8 and the discharge passage 38 is sealed by sealing means consisting of the following four locations. That is, the gap between the reaction piston 55 communicating with the power chamber 8 and the guide portion 5A is sealed by a seal member 68 provided on the inner circumference of the guide portion 5A, and the cylindrical stopper member 6 communicating with the power chamber 8 is sealed.
1 and the annular pin 23 is sealed by a sealing member 69 provided on the outer periphery of the annular pin 23. Further, a cylindrical stopper member 61 communicating with the power chamber 8 and a reaction piston 5 are provided.
5 is the annular member 62 mentioned above, and a relatively long sliding surface 70 in the axial direction between the reaction piston 55 and the input shaft 17.
It is sealed by. Further, the space between the discharge passage 38 and the atmosphere is sealed by seal members 71 and 72 provided on the inner and outer peripheries of the plug 5. In the above configuration, in the non-operating state shown in the figure, in which the brake pedal (not shown) is released, the annular pin 23 is biased rightward by the spring 63 loaded between the annular pin 23 and the plate 19, and the ball valve 22, the power chamber 8 is separated from the exhaust passage 38.
It communicates with the reservoir via. From this state, when the brake pedal is depressed and the input shaft 17 is moved forward, the second valve seat 24 formed at the tip of the annular pin 23 comes into contact with the ball valve 22, causing the discharge passage 38 and the power chamber 8 At the same time, the ball valve 22 is removed from the first valve seat 20 against the spring 21 by the annular pin 23 (point A in FIG. 3), so that the ball valve 22 is not constantly introduced into the pressure chamber 29. Pressure oil is introduced into the power chamber 8 through a gap between the outer circumference of the annular pin 23 and the inner circumference of the plate 19. When pressure oil is introduced into the power chamber 8, the power piston 3 is moved forward to the left against the spring 10, and the reaction piston 55 is displaced to the right against the spring 57. At the initial stage of operation, the reaction piston 55 is kept separated from the stopper 17A of the input shaft 17 by the spring 57. In this state, the acting force of the hydraulic pressure in the power chamber 8 that is applied to the reaction piston 55 is received by the power piston 3 via the spring 57, the retainer 56, and the adjusting screw 58, and the acting force is applied to the input shaft 17. never transmitted. Therefore, the reaction force transmitted to the driver via the input shaft 17 is obtained by the hydraulic pressure in the power chamber 8 that directly acts on the input shaft 17, and since the pressure receiving area of the input shaft 17 at this time is relatively small, , the output increases with a large boost ratio (see straight line B in Figure 3). When the oil pressure in the power chamber 8 rises and the power piston 3 moves forward to the left to perform a substantial braking action, the reaction piston 55 moves to the stopper 1 of the input shaft 17.
7A (point C in Fig. 3). As a result, the acting force applied to the reaction piston 55 is transmitted to the input shaft 17 via the stopper 17A, so the boost ratio becomes smaller.
After this, the output increases with a small boost ratio (straight line D in Figure 3).
reference). At this time, the cylindrical portion 3A of the power piston 3
The elastic force of the spring 57 that biases the reaction piston 55 can be adjusted by rotating the adjustment screw 58 screwed into the opening of the valve, so that the oil pressure at the moment when the reaction piston 55 contacts the stopper 17A can be adjusted. It is possible to adjust the size of , and therefore the position of point C in FIG. 3, to obtain an optimal operating feeling. Furthermore, the resistance from the seal portion that is applied to the input shaft 17 when the brake pedal is depressed is caused by the sliding surface 70 between the reaction piston 55 and the input shaft 17 and the seal member 71 provided on the inner circumference of the plug 5. This is the resistance given by The power chamber 8 and discharge passage 3 are particularly high-pressure.
Since the sealing means between 8 and 8 is the sliding surface 70, the input shaft 1
The resistance of the seal portion applied to the brake pedal 7 can be sufficiently reduced, thereby making it possible to provide a light operation feeling at the initial stage of depression of the brake pedal. moreover,
The seal members 68 and 71 must ensure communication between the passage 42 formed in the input shaft 17 and the passage 43 formed in the plug 5 even when the input shaft 17 moves forward and backward. It is necessary to arrange them apart in the axial direction by a distance greater than the forward/backward movement amount. On the other hand, the sliding surface 70 needs to be formed long in the axial direction in order to obtain a sufficient sealing action. and 71, it is possible to prevent the axial dimension of the hydraulic booster from increasing even if the sliding surface 70 is formed long in the axial direction. Next, the depression of the brake pedal is released from the above-described brake operating state, and the annular pin 23 is released from the spring 63.
When the ball valve 22 is displaced to the right by the first valve seat 2
0, communication between the pressure chamber 29 and the power chamber 8 is cut off. Subsequently, when the second valve seat 24 of the annular pin 23 separates from the ball valve 22, the power chamber 8 opens into the discharge passage 38.
Since it communicates with the reservoir via, the oil pressure in the power chamber 8 decreases and the power piston 3 is retreated to the right. At this time, the retreat of the input shaft 17 is regulated by the stopper 61B of the cylindrical stopper member 61 integrated therewith coming into contact with the retainer 56 integrated with the power piston 3, and in this state, the input shaft 17 is restricted from moving backward. The seated ball valve 22 and the second valve seat 24 of the annular pin 23 are separated by a large distance to ensure a large flow path area between them. When the right end of the power piston 3 is about to come into contact with the plug 5, the stopper 61B of the cylindrical stopper member 61 that was in contact with the retainer 56 comes to come into contact with the guide portion 5A. When the power piston 3 retreats a predetermined distance from this state and stops when its right end comes into contact with the plug 5, the stopper 61B of the cylindrical stopper member 61 is advanced by the predetermined distance relative to the power piston 3, and the annular The second valve seat 24 of the pin 23 is positioned close to the ball valve 22 seated on the first valve seat 20. Therefore, the next time the brake pedal is depressed, the second valve seat 24 immediately seats on the ball valve 22 and cuts off the communication between the power chamber 8 and the reservoir, so it is possible to reduce the loss of stroke at the initial stage of depression of the brake pedal. . Note that the seal member 68 may be provided on the outer periphery of the right end of the reaction piston 55 instead of being provided on the inner periphery of the guide portion 5A, or the seal member 68 may be omitted and the guide portion 5A and the reaction piston The sliding surface with 55 may be used as a sealing means. Furthermore, it is also possible to provide a sealing member here without using the sliding surface 70 as a sealing means. Further, the loss stroke reduction mechanism may be omitted, and in that case, the cylindrical stopper member 61, the annular member 62, and the shim 40 may be omitted, and the annular pin 23 may be integrally formed at the tip of the input shaft 17. good.

As described above, according to the present invention, the set load of the spring is adjusted by the rotation of the adjustment screw, and the boosting ratio is changed from a large boosting ratio at the initial input to a small boosting ratio generated for each hydraulic booster. It is possible to eliminate the variation in the change point to , or change the change point depending on the car model,
The effect is that versatility can be increased.

[Brief explanation of the drawing]

FIG. 1 is a sectional view taken along line II in FIG. 2, showing one embodiment of the present invention.

FIG. 2 is a front view showing a state in which the reaction piston 55 and the cylindrical stopper member 61 shown in FIG. 1 are assembled.

FIG. 3 is a characteristic diagram of the hydraulic booster.

[Explanation of symbols]

1...Housing 3...Power piston
5...Plug (housing) 8...Power chamber 17...Input shaft
17A...Stopper 18...Control valve 55...Reaction force piston
56...retainer

Claims (1)

[Claims] [Claim 1] A power piston slidably provided in a housing, a power chamber formed at the rear of the power piston in the housing, and an input slidably penetrated through the housing from the rear side of the power piston. a control valve that is provided across the power piston and the tip of the input shaft and supplies hydraulic pressure to the power chamber according to the input applied to the input shaft; A reaction piston that is movably provided and is retracted with respect to the input shaft by hydraulic pressure in the power chamber and comes into contact with a stopper provided on the input shaft, and a reaction piston that is elastically mounted between the power piston and the reaction piston. and a spring that holds the reaction piston at a forward position separated from the stopper with a predetermined elastic force. A reaction force device for a hydraulic pressure booster, characterized in that the spring is screwed onto the adjustment screw and the reaction piston is elastically mounted between the adjusting screw and the reaction piston.