JPH0584552U - Hydraulic booster reaction device - Google Patents

Abstract

(57) [Summary] [Structure] Guide part 5 provided on the housing (plug 5)
A is projected into the cylindrical portion 3A of the power piston 3. The reaction force piston 55 is slidably supported by the guide portion 5A, and the input shaft 17 is slidably supported by the reaction force piston 55. Further, a spring 57 for biasing the reaction force piston 55 is arranged in a gap formed between the outer circumference of the guide portion 5A and the inner circumference of the cylindrical portion 3A of the power piston 3. Further, an elastic body 75 is provided at a contact portion between the reaction force piston 55 and the stopper 17A of the input shaft 17 with which the reaction force piston 55 abuts. [Effect] The guide portion 5A, the sliding portion of the reaction force piston 55,
Since the sliding portion of the input shaft 17 and the spring 57 can be arranged in the radial direction while overlapping in the axial direction, it is possible to prevent the axial dimension of the hydraulic booster from becoming large, and the elastic body 75 causes a reaction force. The hitting sound of the piston 55 and the stopper 17A can be suppressed.

Description

[Detailed description of the device] [Industrial applications]

 The present invention relates to a hydraulic booster used in a brake booster or the like, and more particularly to a reaction force booster for a hydraulic booster having a reaction piston.

[Prior Art]

 Conventionally, as a reaction force device of a hydraulic booster, a power piston slidably provided in a housing and having a cylindrical portion at the rear, a power chamber formed at the rear of the power piston in the housing, and An input shaft that extends through the housing from the rear side of the power piston in a sliding manner, and extends over the power shaft inside the cylindrical portion and the tip of the input shaft. And a control valve for supplying hydraulic pressure to the power chamber and a slidable outer periphery of the input shaft, and a hydraulic pressure in the power chamber retracts the input shaft to provide it to the input shaft. A reaction force piston that abuts against the stopper, and a spring that is elastically mounted between the power piston and the reaction piston and that holds the reaction force piston in a forward position separated from the stopper by a predetermined elastic force. Known as (JP-A-2-60871 and JP Hei 2-74456). In the hydraulic booster of the above publication, when the input shaft is moved forward, the control valve supplies the hydraulic pressure corresponding to the input applied to the input shaft to the power chamber, whereby the power piston is moved forward. A boosting action comes to be done. 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 at the same time acts on the reaction force piston to move the reaction force piston against the spring to input shaft. To retreat against. Before the reaction force piston comes into contact with the stopper provided on the input shaft, the hydraulic pressure acts only on the input shaft with a relatively small pressure receiving area, so the output increases with a large boost ratio, and the reaction force piston When the two come into contact with the stopper provided on the shaft and become integrated, the pressure receiving area increases and the output increases with a small boost ratio. And a good operation feeling is secured by such a large boost ratio at the initial stage of operation. Conventionally, although the overall structure is different, various hydraulic boosting devices equipped with a reaction force piston have been proposed (JP-A-55-44095 and JP-A-56-90765).

[Problems to be solved by the device]

 In the reaction force device of the conventional hydraulic booster having the above-mentioned structure, it is necessary to form the sliding portion for the housing and the sliding portion for the reaction force piston in series on the input shaft. There is a drawback that the directional dimension becomes large. There is also a problem that a tapping sound is generated when the reaction force piston comes into contact with a stopper provided on the input shaft to integrate the two. In view of such circumstances, the present invention rationally incorporates the reaction force piston into the hydraulic booster to prevent the axial size of the hydraulic booster from increasing as much as possible. It is also designed to suppress the generation of tapping sounds.

[Means for Solving the Problems]

 That is, the present invention provides a reaction force device for a conventional hydraulic booster having the above-described configuration, wherein the housing is provided with a guide portion protruding into the cylindrical portion of the power piston, and the reaction force piston is provided as described above. The reaction part is slidably fitted in the guide part to slidably support the reaction force piston, and the input shaft is slidably fitted in the shaft part of the reaction force piston to react the reaction force. The input shaft is slidably supported by the piston, and the above-mentioned ridge is arranged in the gap formed between the outer circumference of the guide section and the inner circumference of the cylindrical section of the power piston. An elastic body is provided at the contacting portion with and the tapping sound due to the contact between the elastic body and the elastic body is suppressed.

[Action]

 According to the above structure, the guide portion provided on the housing projects into the cylindrical portion of the power piston, and the reaction force piston is slidably supported by the guide portion, and the input shaft has the reaction force piston. A spring that is slidably supported by the spring and that biases the reaction force piston is arranged in a gap formed between the outer circumference of the guide portion and the inner circumference of the cylindrical portion of the power piston. Therefore, the guide portion, the reaction piston sliding portion, the input shaft sliding portion and the rod can be arranged in the radial direction while axially overlapping each other, whereby the hydraulic booster It is possible to prevent the axial dimension from increasing as much as possible. Further, since an elastic body is provided at the contact portion between the stopper and the reaction force piston and the elastic body suppresses the tapping sound caused by the contact between the stopper and the reaction force piston, the driver does not feel uncomfortable.

【Example】

 The present invention will be described below with reference to the illustrated embodiment. In FIG. 1, a power piston having a bore 2 formed in a housing 1 of a hydraulic booster and a cylindrical portion 3A formed in a rear portion on the right side inside the bore 2. 3 is slidably fitted. The push rod 4 provided at the left end of the power piston 3 is kept liquid-tight and slidably protrudes to the outside of the housing 1. The tip of the push rod 4 is driven by 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 to the housing 1. .. A power chamber 8 into which hydraulic oil is introduced is formed between the plug 5 and the power piston 3, and a spring 10 is provided in a low pressure chamber 9 formed on the opposite side of the power piston 3 from the power chamber 8. The power piston 3 is housed and normally held in the non-actuated position shown in FIG. The low-pressure chamber 9 accommodating the spring 10 communicates with a reservoir (not shown) via a passage 11 formed in the housing 1. An input shaft 17 interlocked with a brake pedal (not shown) is slidably pierced through a plug 5 forming a part of the housing 1, and a left end portion of the input shaft 17 and a cylindrical shape of the power piston 3 are provided. A control valve 18 is provided across the inside of the portion 3A. The control valve 18 includes a first valve seat 20 formed on a plate 19 provided in the cylindrical portion 3A of the power piston 3 and a first valve seat 20 from the side opposite to the power chamber 8 due to the elastic force of a spring 21. A ball valve 22 seated on the upper end of the input shaft 17, an annular pin 23 provided at the tip of the input shaft 17 for separating the ball valve 22 from the first valve seat 20, and further formed at the tip of the annular pin 23. And a second valve seat 24 on which the ball valve 22 is seated. The plate 19 is fixed to the power piston 3 by retainers 56, 56 'and a fixing screw 58 screwed to the cylindrical portion 3A of the power piston 3. In the inoperative state, the ball valve 22 is seated on the first valve seat 20 by the elastic force of the spring 21, and the power chamber 8 formed on the right side of the first valve seat 20 and the pressure chamber formed on the left side of the first valve seat 20. The communication with 29 is cut off. The pressure chamber 29 communicates with a pump (not shown) through a supply passage 30, and the pump constantly supplies the pressure oil of 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 in the outer peripheral surface of the power piston 3, a radial passage 33 formed in the housing 1, and the passage 33. And a conduit (not shown) connecting the pump and the pump. Further, in the non-illustrated 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 discharges the exhaust passage 38. Through the reservoir. The discharge passage 38 includes a passage 39 formed in the shaft portion of the annular pin 23, a passage 41 formed in the shaft portion of a shim 40 interposed between the annular pin 23 and the input shaft 17, and the input shaft 17 It is composed of a passage 42 formed in the shaft portion, a passage 43 formed in the plug 5, and a passage 44 formed in the housing 1. By connecting this passage 44 to the above-mentioned passage 11, the discharge passage is formed. 38 communicates with a reservoir (not shown). Further, the left end of the ball valve 22 constituting the above control valve is made liquid-tight and slidably penetrates through the collar 48, and a balance chamber 49 is formed on the left side of the collar 48. The 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, so that the ball valve 22 has a pressure receiving area on the balance chamber 49 side. 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 as described above, when the input shaft 17 and the annular pin 23 are moved forward and the ball valve 22 is separated from the first valve seat 20, thereby increasing the pressure in the power chamber 8, The ball valve 22 seated on the second valve seat 24 of the annular pin 23 is separated from the second valve seat 24 to prevent liquid leakage. However, the plug 5 forming a part of the housing 1 is provided with a cylindrical guide portion 5A projecting into the cylindrical portion 3A of the power piston 3 at the left end portion thereof, and a reaction force is applied to the guide portion 5A. A piston 55 is slidably fitted and the reaction force piston 55 is slidably supported by the guide portion 5A. Then, the input shaft 17 is slidably fitted to the shaft portion of the reaction force piston 55 so that the input shaft 17 is slidably supported by the reaction force piston 55 supported by the guide portion 5A. There is. A flange portion 55A extending radially outward is formed at the left end of the reaction piston 55. The outer peripheral portion of the flange portion 55A and the retainer 56 provided in the cylindrical portion 3A of the power piston 3 are formed. A spring 57 is elastically mounted in the meantime to normally hold the reaction force piston 55 in the non-actuated position shown in FIG. In this state, the reaction piston 55 is located at the forward position with respect to the input shaft 17 and is separated from the stepped stopper 17A provided on the input shaft 17. Then, as will be described later in detail, when the hydraulic force acting on the reaction force piston 55 in the power chamber 8 exceeds the set load of the spring 57, the reaction force piston 55 acts on the input shaft 17 against the spring 57. It retreats with respect to it, and comes into contact with the stopper 17A. As a result, before the reaction force piston 55 comes into contact with the stopper 17A, the hydraulic force acting on the reaction force piston 55 in the power chamber 8 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 acting force is transmitted to the input shaft 17 as a reaction force, so that before and after the reaction force piston 55 comes into contact with the stopper 17A. The boost ratio can be changed. Further, the spring 57 and the retainer 56 are arranged in 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 non-illustrated operating state, the guide portion 5A, the sliding portion of the reaction force piston 55 with respect to the guide portion 5A, the sliding portion of the input shaft 17 with respect to the reaction force piston 55, and the reaction force The spring 57 for urging the piston 55 is arranged in the radial direction while axially overlapping each other. As a result, for example, the axial dimension of the hydraulic booster can be reduced as compared with the conventional device in which the sliding portion of the reaction force piston 55 and the sliding portion of the input shaft 17 are arranged in series in the axial direction. Can be reduced. Next, the loss stroke reduction mechanism at the initial stage of operation of the input shaft 17 will be described. A step portion 17B having a reduced diameter on the tip side is formed at the tip of the input shaft 17, and the tip side from the step 17B is formed. The tubular stopper member 61 is inserted into a radially inner flange portion 61A formed at the right end portion of the tubular stopper member 61, and the flange portion 61A of the tubular stopper member 61 is brought into contact with the step portion 17B. Then, the tubular stopper member 61 is fixed to the input shaft 17 by press-fitting the annular member 62 between the outer circumference of the input shaft 17 and the inner circumference of the tubular stopper member 61 on the tip side of the step portion 17B. At the same time, it maintains liquid tightness between the two. As shown in FIG. 2, a stopper 61B projecting outward in the radial direction is integrally formed at a radially opposite position on the left end portion of the cylindrical stopper member 61, and each stopper 61B is The reaction force piston 55 is projected outward from the shaft portion of the reaction force piston 55 through a diametrical slit 55B formed in the flange portion 55A of the reaction force piston 55. Then, the shim 40 and the annular pin 23 are sequentially inserted into the cylindrical stopper member 61, and the spring 63 is elastically mounted between the annular pin 23 and the plate 19 in the non-illustrated operating state. The stopper 61B is brought into contact with the left end surface of the guide portion 5A to restrict the backward movement of the input shaft 17. On the other hand, the left end of the retainer 56 is extended to the right side position adjacent to the stopper 61B so that the retainer 56 can restrict the retreat of the input shaft 17 when the power piston 3 is retracted. .. By the way, the outer side in the radial direction of the power chamber 8 formed in the bore 2 is kept liquid-tight by the seal member 66 provided on the outer periphery of the plug 5 and the seal member 67 provided on the outer periphery of the power piston 3. is doing. On the other hand, the space between the radially inner side of the power chamber 8 and the discharge passage 38 is sealed by the following four sealing means. That is, the gap between the reaction force piston 55 communicating with the power chamber 8 and the guide portion 5A is sealed by the seal member 68 provided on the inner circumference of the guide portion 5A, and the cylindrical stopper member 61 communicating with the power chamber 8 is provided. The gap between the ring pin 23 and the ring pin 23 is sealed by a seal member 69 provided on the outer periphery of the ring pin 23. Further, the gap between the cylindrical stopper member 61 communicating with the power chamber 8 and the reaction force piston 55 is relatively long sliding in the axial direction between the annular member 62 and the reaction force piston 55 and the input shaft 17. It is sealed by the face 70. Further, the discharge passage 38 and the atmosphere are sealed by seal members 71 and 72 provided on the inner and outer circumferences of the plug 5. Further, an elastic body 75 is provided at a contact portion between the reaction force piston 55 and the stopper 17A of the input shaft 17 with which the reaction force piston 55 abuts, and the elastic body 75 suppresses a tapping sound due to the contact between the two. That is, in this embodiment, the annular groove 76 is formed on the small diameter side of the step portion of the input shaft 17 formed to form the stopper 17A, and the ring-shaped elastic body 75 is provided in the annular groove 76. There is. The outer peripheral surface of the elastic body 75 is protruded from the annular groove 76 by a predetermined amount, and a taper surface 77 is formed on the inner peripheral surface of the right end portion of the reaction force piston 55. I am able to contact them. In the above-described structure, when the brake pedal (not shown) is released, the annular pin 23 is urged to the right by the spring 63 mounted between the annular pin 23 and the plate 19 in the inoperative state. Separated from the ball valve 22, the power chamber 8 communicates with the reservoir via a discharge passage 38. From this state, when the brake pedal is depressed and the input shaft 17 is advanced, the second valve seat 24 formed at the tip of the annular pin 23 abuts the ball valve 22 and the exhaust passage 38 and the power chamber. 8 and the ball valve 22 is separated 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 always introduced into the pressure chamber 29. The pressure oil that has been retained is introduced into the power chamber 8 through the gap between the outer periphery of the annular pin 23 and the inner periphery of the plate 19. When pressure oil is introduced into the power chamber 8, the power piston 3 is moved leftward against the spring 10 and the reaction force piston 55 is displaced rightward against the spring 57. At the beginning of its operation, the reaction force 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 applied to the reaction force piston 55 is received by the power piston 3 via the spring 57, the retainer 56 and the fixing screw 58, and the acting force is applied to the input shaft 17. Not 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 the pressure receiving area of the input shaft 17 at this time is relatively small. Therefore, the output increases with a large boost ratio (see the straight line B in FIG. 3). When the hydraulic pressure in the power chamber 8 rises and the power piston 3 advances to the left and a substantial braking action is performed, the reaction force piston 55 contacts the stopper 17A of the input shaft 17 ( (Point C in FIG. 3). As a result, the acting force applied to the reaction force piston 55 is transmitted to the input shaft 17 via the stopper 17A, so that the boosting ratio becomes smaller, and thereafter the output rises at a small boosting ratio (see FIG. 3). See straight line D). At this time, the reaction force piston 55 first comes into contact with the elastic body 75 provided on the input shaft 17 by the tapered surface 77 of the inner peripheral surface of the right end portion thereof, and the elastic body 75 is compressed and deformed into the annular groove 76. However, the right end surface of the reaction force piston 55 comes into contact with the stopper 17A of the input shaft 17. Therefore, it is possible to suppress the tapping sound of the reaction force piston 55 and the stopper 17A, and it is possible to prevent the elastic body 75 from being compressed and deformed more than necessary. Further, the resistance from the seal portion applied to the input shaft 17 when the brake pedal is depressed is due to the sliding surface 70 between the reaction force piston 55 and the input shaft 17 and the seal member 71 provided on the inner periphery of the plug 5. It is the resistance given by. Since the sealing means between the power chamber 8 and the discharge passage 38, which have a particularly high pressure, is the sliding surface 70, the sealing portion added to the input shaft 17 is smaller than that when a rubber sealing member is provided between them. The resistance can be made sufficiently small, and as a result, the operation feeling at the initial stage of depression of the brake pedal can be made light. Further, since the seal members 68 and 71 must secure the communication between the passage 42 formed in the input shaft 17 and the passage 43 formed in the plug 5 even if the input shaft 17 moves back and forth, the input It is necessary to dispose the shaft 17 so as to be separated from the shaft 17 in the axial direction by an amount equal to or larger 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. Since it is formed within the space between the seal members 68 and 71, it is possible to prevent the axial dimension of the hydraulic booster from increasing even if the sliding surface 70 is formed to be long in the axial direction. Next, when the brake pedal is released from the above-described brake operating state and the above annular pin 23 is displaced to the right by the spring 63, the ball valve 22 is seated on the first valve seat 20, so the pressure chamber 29 And the communication with the power chamber 8 are cut off. Subsequently, when the second valve seat 24 of the annular pin 23 is separated from the ball valve 22, the power chamber 8 communicates with the reservoir via the discharge passage 38, so that the hydraulic 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 restricted by the stopper 61B of the cylindrical stopper member 61 integral with the input shaft 17 contacting the retainer 56 integral with the power piston 3, and in this state, the first valve seat 20 The ball valve 22 seated on the second valve seat 24 and the second valve seat 24 of the annular pin 23 are largely separated from each other to secure a large flow passage area therebetween. 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, which has been in contact with the retainer 56, comes into contact with the guide portion 5A. When the power piston 3 retreats from this state by a predetermined distance and its right end contacts the plug 5 and stops, the stopper 61B of the tubular stopper member 61 is advanced by the predetermined distance with respect to the power piston 3, The second valve seat 24 of the annular pin 23 is positioned near the ball valve 22 seated on the first valve seat 20. Therefore, when the brake pedal is next stepped on, the second valve seat 24 immediately sits on the ball valve 22 to cut off the communication between the power chamber 8 and the reservoir. it can. The seal member 68 may be provided on the outer circumference of the right end portion of the reaction force piston 55 instead of being provided on the inner circumference of the guide portion 5A, or the seal member 68 may be omitted to react with the guide portion 5A. The sliding surface with the piston 55 may be used as the sealing means. Further, it is possible to provide a sealing member here without using the sliding surface 70 as a sealing means. Further, the loss stroke reducing mechanism may be omitted. 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 formed integrally with the tip portion of the input shaft 17. Good. Next, FIG. 4 shows another embodiment of the present invention. In this embodiment, an annular step portion 76 'is formed on the inner peripheral side of the right end portion of the reaction force piston 55, and an elastic body 75 is provided therein. ing. The elastic body 75 is projected from the right end surface of the reaction force piston 55 by a predetermined amount, and when the reaction force piston 55 and the stopper 17A come into contact with each other, after the elastic body 75 comes into contact with the stopper 17A, the next reaction The outer peripheral portion of the right end surface of the force piston 55 contacts the stopper 17A. Further, FIG. 5 shows another embodiment of the present invention. In this embodiment, an elastic body 75 is provided on the stopper 17A so that the right end surface of the reaction piston 55 is elastically contacted with the elastic body 75. The reaction piston 55 and the stopper 17A are prevented from directly contacting each other. At this time, an annular groove is provided on the inner peripheral side of the end face of the stopper 17A to accommodate the elastic body 75 therein, so that the elastic body 75 is prevented from being deformed more than necessary as in the above two embodiments. Good. On the contrary, in FIG. 4, the reaction force piston 55 and the stopper 17A may be brought into contact with each other via the elastic body 75 so that the two do not come into direct contact with each other.

[Effect of the device]

 As described above, according to the present invention, even in a hydraulic booster having a reaction force piston, it is possible to prevent an increase in the axial dimension thereof as much as possible, and a stopper for the input shaft. Since the impact sound of the reaction piston and the reaction force piston can be suppressed by the elastic body, an effect that the driver is not uncomfortable can be obtained.

[Brief description of drawings]

1 is a sectional view taken along the line I-I of FIG. 2, showing an embodiment of the present invention.

FIG. 2 is a front view showing an assembled state of a reaction force piston 55 and a cylindrical stopper member 61 shown in FIG.

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

FIG. 4 is a sectional view of an essential part showing another embodiment of the present invention.

FIG. 5 is a sectional view of an essential part showing still another embodiment of the present invention.

[Explanation of symbols]

1 ... Housing 3 ... Power piston 3
A ... Cylindrical part 5 ... Plug (housing) 5A ... Guide part
8 ... Power chamber 17 ... Input shaft 17A ... Stopper 1
8 ... Control valve 55 ... Reaction force piston 57 ... Spring 7
5 ... Elastic body

Claims (1)

[Scope of utility model registration request] 1. A power piston slidably provided in a housing and having a cylindrical portion at a rear portion thereof, a power chamber formed at a rear portion of the power piston in the housing, and a rear portion of the power piston in the housing. An input shaft slidably penetrated, a power piston inside the tubular portion, and a tip portion of the input shaft are provided over the input shaft, and a hydraulic pressure corresponding to an input applied to the input shaft is applied to the power chamber. And a reaction force piston slidably provided on the outer circumference of the input shaft, retracted with respect to the input shaft by hydraulic pressure in the power chamber, and abutting against a stopper provided on the input shaft. In a reaction force device of a hydraulic booster, which is elastically mounted between the power piston and the reaction force piston and has a spring for holding the reaction force piston at a forward position separated from the stopper by a predetermined elastic force. , The above house Is provided with a guide portion projecting into the cylindrical portion of the power piston, the reaction force piston is slidably fitted in the guide portion, and the reaction force piston is slidably supported by the guide portion. The input shaft is slidably fitted to the shaft portion of the reaction force piston so that the reaction force piston slidably supports the input shaft, and the spring is provided in the outer periphery of the guide portion and the cylindrical portion of the power piston. It is characterized in that it is arranged in a gap formed between the circumference and an elastic body at the contact portion between the stopper and the reaction force piston, and that the elastic body suppresses the tapping sound due to the contact between them. Reaction force device for hydraulic booster.