JP2000203408A - Travel limiter hydraulic booster - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of vibration sound of a ball valve in a travel limiter and fluid sound even when abrupt depressing and abrupt returning of a brake pedal is repeated. SOLUTION: A tip portion 20a of an input rod 20 is slidably fitted in a hole formed on a back surface of a power piston. A travel limiter is provided within the tip portion 20 a of the input rod 20. The travel limiter comprises a valve seat 67a formed in an inner surface of a cylindrical member 67 fixed within a hole 20e of the tip portion 20, a ball valve 70, a retainer 100, a guide member 102 fixed on an opening of the cylindrical member 67, and a spring 104 disposed between the retainer 100 and the guide member 102. A guide hole 102b is formed on the guide member 102, and one end 100a of the retainer 100 is slidably fitted to a first opening, and a throttle member 106 having a small diameter passage is fixed to a second opening, thereby forming a damper chamber 108. Even when the ball valve 70 repeats opening and closing, vibration is absorbed by the damper chamber 108 to prevent the generation of abnormal sound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic booster used for a vehicle brake device and the like.
The present invention relates to a travel limiter that is provided between an input rod and a power piston, disconnects communication between a hole in the power piston and a power pressure chamber, and connects and disconnects the input rod and the power piston.

[0002]

2. Description of the Related Art FIG. 3 is a longitudinal sectional view of a general hydraulic booster, and the overall structure of the hydraulic booster will be described with reference to FIG. Front body 2
A large-diameter power cylinder 10 in which a power piston 8 is fitted to move forward and backward, and an input piston 12 are fitted to move forward and backward in a housing 6 formed by abutting the left side of the figure with the rear cover 4. And a small-diameter input cylinder 14 are provided on the same axis.

A large-diameter outer peripheral portion of the power piston 8 slides on the inner surface of the power cylinder 10, and a small-diameter cylindrical portion 8 a is provided integrally with the axis of the power piston 8 to form the power cylinder 10. A front wall 2 a of the front body 2 is slidably penetrated through a seal member 17. Internal hole 8c of this small diameter cylindrical portion 8a
Is connected to a push rod 16 to transmit an output to a piston of a master cylinder (not shown). A return spring 18 for returning the power piston 8 to the inoperative position shown in the drawing is arranged between the front side of the power piston 8 and the front wall 2a.

[0004] As described above, the push rod 16 is inserted into the internal hole 8c of the small-diameter cylindrical portion 8a of the power piston 8, so that the push rod 16 does not fall off the power piston 8.
A rubber stopper 19 is fitted to the rear end.

The rear side of the power piston 8 (right side in FIG. 3)
Is formed with a circular hole 8b, and the large-diameter portion 20a of the distal end of the input rod 20 is slidably fitted in the hole 8b.
The other end 20b of the input rod 20 is connected to the front end 12a of the input piston 12 and moves forward and backward integrally. The rear end 12b of the input piston 12 is connected to a brake pedal (not shown) via an operating rod 22, and the operation of the brake pedal causes the input piston 12 and the input rod 20 to move forward and backward.

In the front body 2 of the housing 6, the power cylinder 1 which is arranged on the same axis is arranged.
A valve hole 24 is formed in parallel with 0 and the input cylinder 14. In this valve hole 24, a spool 26 is slidably fitted and a spool valve (reference numeral 28 as a whole) is provided.
). The housing 6 is fixed by the bolts 30 with the front body 2 and the rear cover 4 abutting against each other as described above, and the space between the body 2 and the cover 4, that is, between the power cylinder 10 and the input cylinder 14. And the space on the right side of the valve hole 24 constitute a power pressure chamber 32 to be described later.

On the inner surface of the valve hole 24, two annular grooves 2 are provided.
4a and 24b are formed, while two annular grooves 26a and 26b are also formed on the outer peripheral surface of the spool 26.
The annular groove 26 on the right side of FIG.
“a” is always connected to the discharge side of the pump 35 via a discharge passage 34 formed in the housing 6 and opening into the valve hole 24. Also, the annular groove 26 on the left side of the spool 26
The b is always in communication with the reservoir 37 via the return passage 36.

On the other hand, the wide annular groove 24a formed on the right side of the valve hole 24 is always connected to the discharge side of the pump 35 when the spool 26 is not operated (the state shown in FIG. 3). It is connected to the right annular groove 26a, and when the spool 26 operates, the flow path between the annular groove 26a is gradually narrowed, and is finally shut off from the annular groove 26a. In addition, the annular groove 24a is
It is always connected to a power steering (not shown) through a cable 8. This power steering is an open center type power steering, and when not operated, the liquid discharged from the pump 35 is returned to the reservoir 37 through the flow path of the control valve. Then, when the steering wheel is operated, the flow path of the control valve is narrowed to generate pressure, and the pressure operates the cylinder of the power steering to steer the wheels. In this embodiment, one pump 35 is also used as an open center type power steering system, but a system using one pump only for the brake may be used. In this case, for example, the spool valve 28
The right annular groove 24a formed on the inner surface of the valve hole 24 is directly connected to the reservoir 37.

Further, an annular groove 24b formed on the left side of the inner surface of the valve hole 24 communicates with an axial passage 26d in the spool 26 through a radial through hole 26c formed in the spool 26. . The axial passage 26d is provided with a radial through-hole 26e formed in a portion protruding from the valve hole 24 on the right side of the spool 26.
Through the power pressure chamber 32.

A plug 40 is fixed to an end (left end in FIG. 3) of the valve hole 24 opposite to the power pressure chamber 32.
Between the plug 40 and the end of the spool 26, a chamber 42 communicating with the axial passage 26d is formed.
A spring 44 is disposed in the chamber 42 and constantly biases the spool 26 rightward in FIG. When the spool valve 28 is not operated, the right end surface of the spool 26 is pressed by the spring 44 and stops against the wall surface of the power pressure chamber 32 in the housing 6 as shown in the figure. In the non-operating state, the annular groove 26a on the right side of the spool 26 into which the hydraulic fluid discharged from the pump 35 is constantly introduced, and the wide annular surface of the inner surface of the valve hole 24 connected to the reservoir 37 via power steering. The groove 24a communicates with the
The liquid discharged from the pump 35 passes through the grooves 26a, 24a and the control valve of the power steering, and the reservoir 37
Reflux. The annular groove 2 on the left side of the valve hole 24
4b is interrupted from communicating with the annular groove 26a on the right side of the spool 26, and communicates with the annular groove 26b on the left side of the spool 26 which is constantly connected to the reservoir 37. 37.

As will be described later, when the spool 26 moves to the left in the drawing, first, an annular groove 26a formed on the right side of the spool 26, into which a discharge liquid from a pump 35 is introduced, and a valve hole 24. Between the annular groove 24a connected to the reservoir 37 via the power steering on the right side and the annular groove 24b on the left side of the valve hole 24 and the annular groove 26b communicating with the reservoir 37 on the left side of the spool 26. Close between and. Further spool 26
Moves leftward, the annular groove 26a connected to the pump 35 on the right side of the spool 26 and the annular groove 24b connected to the power pressure chamber 32 on the left side of the valve hole 24 communicate with each other to discharge from the pump 35. The liquid is introduced into the power pressure chamber 32.

The power piston 8, the input rod 20, and the spool 26 are operatively connected via a lever 46 disposed in the power pressure chamber 32. This lever 4
Numeral 6 denotes two plates disposed on both sides of the input rod 20 and the spool 26 and integrally connected by a horizontal plate 46a (located on the near side and the far side of the sheet of FIG. 3).
Consists of A stopper member 48 for restricting a retreat limit of the power piston 8 is attached to a rear end surface (right side in FIG. 3) of the power piston 8.
Is connected to this stopper member 48 via a first connection pin 50.

An umbrella-shaped retainer 51 and a sleeve 52 are slidably fitted on the outer periphery of a portion of the spool 26 projecting into the power pressure chamber 32. The retainer 51 and the sleeve 52 are provided between the inner periphery of the retainer 51 and the spool 2.
1 is biased rightward in FIG. 1 by a spring 54 interposed between the stepped portion formed on the outer peripheral surface of the sleeve 6 and the end (right end) of the sleeve 52 fits on the outer periphery of the end of the spool 26. It stops by hitting the stopper ring 56 that is worn. The lower end 46c of the lever 46 is connected to the outer peripheral surface of the sleeve 52 via a second connecting pin 57. The retainer 51 and the sleeve 52 are connected to the lower end 4 of the lever 46.
6c swings forward and backward, and during normal operation, the swing of the lever 46 causes the retainer 51, the sleeve 52, and the spool 26 to move integrally.
Also, the spool 26 moves to the left in FIG.
After the stop, the retainer 51 and the sleeve 5
2 moves along the outer peripheral surface of the spool 26.

An intermediate plate 60 is disposed inside the lever 46 located on each side of the input rod 20.
Both side portions of the intermediate plate 60 are located between both side walls of the lever 46 and the input rod 20, and the input rod 20 penetrates between both side portions. This intermediate plate 60
The third connecting pins 62 respectively attached to both sides of the lever 46 engage in long grooves 46d formed on both side walls of the lever 46. A spring 64 is mounted between the inside of the intermediate plate 60 and the input piston 12, and the intermediate plate 60 is urged by the spring 64 toward the distal end portion 20a of the input rod 20. The tip 20a of the input rod 20 is connected to another part (shaft) 20c.
The intermediate plate 60 is pressed against a step 20d between the large-diameter portion 20a and the small-diameter shaft portion 20c of the input rod 20 during normal operation.

As described above, the circular hole 8b is formed on the rear side of the power piston 8, and the input rod 2 is formed in the hole 8b.
The large diameter portion 20a at the leading end of the zero is fitted. A travel limiter 66 is provided inside the large-diameter portion 20a at the distal end of the input rod 20. The travel limiter 66 will be described in detail with reference to FIG. Passage holes 20e and 20f are formed to pass obliquely between the distal end surface of the large diameter portion 20a of the input rod 20 and the step portion 20d between the large diameter portion 20a and the small diameter shaft portion 20c. The passage holes 20e and 20f are composed of a large-diameter hole 20e on the distal end surface side of the input rod 20 and a small-diameter hole 20f on the step portion 20d side, and the cylindrical member 67 is press-fitted into the large-diameter hole 20e.
A valve seat 67a is formed on the inner surface of the bottom (small-diameter hole 20f side) of the cylindrical member 67 so that a valve element (ball valve) 70 pressed by a spring 68 disposed on the tip end side of the input rod 20 is seated. Has become.

A small step 20g is formed on the inner surface of the large-diameter hole 20e.
On the other hand, a small step 67b is also provided on the outer surface of the cylindrical member 67, and the small step 67b of the cylindrical member 67 is provided.
Are fixed in contact with the small step portion 20g of the large diameter hole 20e. In a state where the cylindrical member 67 is fixed to the input rod 20, there is a gap between the outer surface of a portion inside the small step portion 67b of the cylindrical member 67 and a portion inside the small step portion 20g of the large diameter hole 20e. Are formed so as not to contact each other.

A plunger (pin for pressing the ball valve 70) 72 is inserted into the small-diameter hole 20f of the passage hole. Usually, the plunger 72 pressed by the intermediate plate 60 pushes up the ball valve 70. As a result, a circular hole 8 b formed in the power pressure chamber 32 and the power piston 8 is formed.
It communicates with the inner chamber 74. Also, the intermediate plate 60
Moves away from the step portion 20d of the input rod 20, the plunger 72 pushing up the ball valve 70 retreats, the ball valve 70 sits on the valve seat 67a in the cylindrical member 67, and the chamber 74 inside the power piston 8 is closed. It is shut off from the power pressure chamber 32 and sealed. When the internal chamber 74 is thus sealed, the input of the input rod 20 is directly transmitted to the power piston 8.

Further, an emergency accumulator 73 is connected to the hydraulic booster. The hydraulic booster according to this embodiment is of an open center type, and a booster action of the booster is performed by a pump discharge pressure generated at the time of a brake operation. Therefore, when the pump 35 breaks down, the pump discharge pressure is not generated, and the booster function of the booster may be impaired. Therefore, the pump discharge pressure generated during the operation of the booster is accumulated in the emergency accumulator 73, and the accumulated pressure is released in the event of an emergency such as a failure of the pump to perform a boosting action. The emergency accumulator 73 is provided with a charge valve 75 for accumulating pressure, and a dump valve 84 that is opened when the pump 35 fails or the like and discharges the accumulating pressure of the accumulator 73 to the power pressure chamber 32. I have.

As shown in an enlarged view in FIG. 5, the charge valve 75 has a stepped valve hole 76 for communicating the pump discharge passage 34 formed in the housing 6 (front body 2) with the power pressure chamber 32. It is provided within. Stepped hole 7
A cylindrical valve body 78 is slidably fitted in the small-diameter portion 76a. Inlet side of this stepped hole 76 (discharge passage 34 side)
An annular rubber sheet 80 is fixedly attached to the pump 35. When not operating, the valve 78 is seated on the rubber sheet 80 and the pump 35
And the accumulator 73 are shut off. Then, when pressure is generated on the discharge side of the pump 35, the valve body 78 moves away from the rubber sheet 80 to the right by this pressure, and the pump 3
The hydraulic fluid discharged from 5 is supplied to the accumulator 73 through the gap on the outer periphery of the valve body 78 and the passage 81 to be accumulated. Note that a relief valve 82 is provided in the charge valve 75, and is opened when the pressure accumulated in the accumulator 73 becomes excessively high to reduce the accumulated pressure.

A dump valve 84 is provided in the large-diameter portion 76c located on the power pressure chamber 32 side of the stepped valve hole 76 to open in an emergency and release the pressure in the accumulator 73 into the power pressure chamber 32. Have been. Large diameter part 7 of stepped hole 76
A sheet member 86 having a passage hole 86a penetrating the center portion is press-fitted and fixed in the opening of the power pressure chamber 32 on the side of 6c. An O-ring 88 is fitted around the outer periphery of the sheet member 86 to maintain liquid tightness between the accumulator 73 and the power pressure chamber 32. The end face 86b (right end face in FIG. 5) 86b of the seat member 86 press-fitted and fixed in the stepped hole 76 substantially coincides with the end face 2b of the front body 2, and the rear cover 4 fixed integrally with the front body 2 End face 4
a so as not to come out of the stepped valve hole 76.

A passage hole 86 formed in the sheet member 86
A valve seat 86c is provided at the opening of the accumulator 73 side (the left side in FIG. 5), and a ball valve 90 that can be seated on the valve seat 86c is disposed on the valve seat 86c side. The ball valve 90 is accommodated in a cup-shaped ball accommodating member (cover) fitted to an inner end of the seat member 86 and held in the 92 so as not to fall off. A gap is formed between the outer surface of the ball housing member 92 and the inner surface of the stepped valve hole 76. A radial liquid passage 92 communicating between the inside and the outside is formed in a side wall of the ball housing member 92.
a is provided.

Further, an annular guide member 94 is fixed inside the seat member 86, and the ball valve 90 is inserted into a guide hole 94a passing through the center of the guide member 94.
Is pushed up to open the dump valve 84.
Are slidably inserted. Tip 96a of pin 96
Is inserted into the passage hole 86a of the sheet member 86 with a gap therebetween to form a hydraulic pressure passage 98, and the other end 96b protrudes into the power pressure chamber 32. A large-diameter portion 96c is formed on the outer periphery of a substantially central portion of the pin 96.
Is prevented from dropping off from the guide member 94. The guide member 94 has a passage hole 86 formed in the sheet member 86.
and a through-passage 94b which constantly communicates with the inside of the power pressure chamber 32 is formed. In the dump valve 84 having this configuration, when the retainer 51 fitted to the outer periphery of the spool 26 moves and presses the pin 96, the ball valve 90 separates from the valve seat 86c and opens.

Next, the operation of the hydraulic booster according to the above configuration will be described. During non-operation, the right end of the spool 26 comes into contact with the wall surface of the power pressure chamber 32 in the housing 6 and stops. When the spool 26 is in this state, the annular groove 26a on the right side of the spool 26 and the valve hole 2
4 and the right annular groove 24a of the spool 26 and the left annular groove 24b of the valve hole 24.
Further, the annular groove 24b on the left side of the valve hole 24 and the annular groove 26b on the left side of the spool 26 communicate with each other. Accordingly, the power pressure chamber 32 includes a radial through hole 26e near the right end of the spool 26, an axial passage 26d in the spool 26, a radial through hole 26c on the left side of the spool 26, and an annular groove 24b on the left side of the valve hole 24. And the reservoir 3 through the annular groove 26b on the left side of the spool 26.
It communicates with 7. The liquid discharged from the pump 35 is
It is sent to the power steering (not shown) through the annular groove 26a on the right side of the spool 26, the annular groove 24a on the right side of the valve hole 24, and the passage 38 in the housing 6, and passes through the flow path in the control valve to the reservoir. Reflux to 37.

When a brake pedal (not shown) is depressed,
When the operating rod 22 moves forward (moves to the left in FIG. 3), the input piston 12 and the input rod 20 connected to the operating rod 22 move forward integrally. When the input rod 20 advances in this way, first, the lever 46 rotates about the second connection pin 57 on the spool 26 side as a fulcrum, and advances the power piston 8. The push rod 16 advances with the advance of the power piston 8, and presses the piston of the master cylinder to generate a master cylinder pressure. When the master cylinder pressure starts to be generated, the advance of the power piston 8 is almost stopped, and the lever 46 starts to rotate about the first connecting pin 50 on the power piston 8 side as a fulcrum, and the sleeve 52 and the retainer 51 are moved. The spool 26 is advanced to the left in FIG. At this time, the spool 26 moves the input rod 20 by the lever ratio with the power piston 8 side as a fulcrum.
Stroke by expanding the stroke of.

When the spool 26 moves to the left in FIG.
An annular groove 26a connected to the pump 35 on the right side of the spool 26 and a wide annular groove 24a on the right side of the valve hole 24.
And the space between the left annular groove 26b of the spool 26 and the left annular groove 24b of the valve hole 24 is closed. Next, the annular groove 26 on the right side of the spool 26
a and the flow path between the annular groove 24b on the left side of the valve hole 24 is opened. When the flow path is switched in this way by the movement of the spool 26, pressure is generated in the liquid discharged from the pump 35, and the annular groove 26a on the right side of the spool 26, the valve hole 24
Through the left annular groove 24b, the radial through hole 26c of the spool 26, the axial passage 26d, and the right radial hole 26e of the spool 26, the liquid discharged from the pump 35 is introduced into the power pressure chamber 32. You.

The power supplied to the power pressure chamber 32 pushes the power piston 8 to the left, and boosts the force of the push rod 16 pressing the piston of the master cylinder.
The pressure in the power pressure chamber 32 is thus increased by the power piston 8.
And acts as a force to push the input piston 20 rightward. Since the spool 26 is balanced in a state where the pressure in the power pressure chamber 32 and the input from the brake pedal are balanced (intermediate load state), the lever 46 pivots about the pin 57 on the spool 26 side. As a result, the pressure in the power pressure chamber 32 matches the input, and a boosting action is performed in an intermediate load state. At this time, the power piston 8
The stroke of the input rod 20 is enlarged by the lever ratio with the spool 26 as a fulcrum. Further, the charge valve 75 is opened by the pressure generated in the pump discharge liquid, and the pump discharge liquid is stored in the accumulator 73.
And is accumulated.

In a state where the input of the brake pedal is increased and the pressure in the power pressure chamber 32 does not increase any more, that is, the left end of the spool 26 abuts on the plug 40, and the annular groove 26a on the right side of the spool 26 and the valve hole When the flow path between the annular groove 24a on the right side of the ring 24 and the annular groove 24a is completely closed (this state is called a full load point), the input rod 20
Only one will move forward. When only the input rod 20 advances, the intermediate plate 60 connected to the lever 46 by the third connecting pin 62 separates from the step 20d of the input rod 20 and is pushed by the intermediate plate 60 until the ball valve 70 is released. The plunger 72 that has been pushed up is retracted, and the ball valve 70 is seated on the valve seat 67 a in the cylindrical member 67. As a result, the chamber 74 between the distal end surface of the input rod 20 and the circular hole 8b of the power piston 8 is
To be sealed. Thereafter, the force applied to the input rod 20 is applied directly to the power piston 8. That is, after the full load point, the output increases by the increase of the input.

When the brake pedal is released from the operating state, the input rod 20 is retracted, and the lever 46 is rotated counterclockwise around the first connecting pin 50 on the power piston 8 side to rotate the spool 26. Move 3 to the right. Due to the movement of the spool 26, the annular groove 26a connected to the pump 35 on the right side of the spool 26 and the annular groove 2 communicating with the power pressure chamber 32 on the left side of the valve hole 24.
4b is closed and the valve hole 24 is closed.
The flow path between the left annular groove 24b of the spool 26 and the annular groove 26b connected to the left reservoir 37 of the spool 26 opens, and the right annular groove 26a of the spool 26 and the valve hole 24 are opened.
The gap between the annular groove 24a on the right side of FIG. Thus, the pressure introduced into the power pressure chamber 32 is discharged to the reservoir 37 through the passages 26e, 26d, 26c and the annular grooves 24b, 26b inside the spool 26.

When the pressure in the power pressure chamber 32 is discharged to the reservoir 37, the power piston 8 retreats and returns to the inoperative position shown in FIG. Further, since the flow path between the right annular groove 26a of the spool 26 and the right annular groove 24a of the valve hole 24 expands to the original state, the pressure generated by narrowing this flow path is eliminated. The liquid discharged from the pump 35 is returned to the reservoir 37 as it is through the control valve of the power steering. At this time, the charge valve 75 of the accumulator 73 is closed and the accumulator 73 is closed.
Is retained as it is.

If the pump 35 breaks down, the brake pedal is depressed and the input rod 20 moves forward.
The spool 26 is moved to the left in FIG.
Is switched, the pressure from the pump 35 is not supplied to the power pressure chamber 32. If the spool 26 cannot move forward any more due to the full stroke, the sleeve 52 and the retainer 51 move forward by bending the spring 54 with the rotation of the lever 46, and first, the axial passage 26 d in the spool 26 and the power The radial through hole 26 e communicating with the inside of the pressure chamber 32 is closed by the sleeve 52. When the sleeve 52 and the retainer 51 further move forward, the retainer 51 hits the pin 96 of the dump valve 84 and presses it. When the pin 96 is pushed and moved, the ball valve 90 is separated from the valve seat 86c and the dump valve 84 is opened. Then, the pressure accumulated in the accumulator 73 is applied to the radial liquid passage 92 a formed in the ball housing member 92, the gap between the ball valve 90 and the valve seat 86 c, the passage hole 86 a of the seat member 86 (the pin 96). The power is supplied to the power pressure chamber 32 through the hydraulic passage 98 between the outer surface of the distal end portion and the through passage 94b of the guide member 94, and the boosting action is started.

[0031]

The above-described hydraulic booster operates as follows when the brake pedal is repeatedly depressed and returned rapidly so that the pedaling force is equal to or greater than the full load point input while the engine is on. I do. That is, in an intermediate load state, the ball valve 70 of the travel limiter 66 is open.
Since the power piston 8 moves relative to the input rod 20, the power piston 8 makes a larger stroke than the input rod 20, and the chamber 74 between the input rod 20 and the power piston 8 rotates. Is increased, and the liquid in the power pressure chamber 32 is supplied into the chamber 74. When the input exceeds the full load point, the ball valve 70 is closed, the chamber 74 is closed, and the power piston 8 and the input rod 20 are integrally stroked.
Also, when the valve is suddenly returned, the ball valve 70 is opened, the power piston 8 returns larger than the input rod 20, the volume of the chamber 74 decreases, and the liquid in the chamber 74 is removed from the power pressure chamber 32.
Is returned to. If you step quickly and return suddenly like this,
Since the opening and closing of the ball valve 70 and the supply and discharge of the liquid into the chamber 74 are performed rapidly, generation of abnormal noise due to vibration of the ball valve 70,
There is a problem that a fluid noise is generated due to a sudden supply and discharge of the liquid.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and prevents the occurrence of abnormal noise and fluid noise due to the vibration of the ball valve of the travel limiter when the hydraulic booster is operated. It is an object of the present invention to provide a hydraulic booster travel limiter that does not cause discomfort.

[0033]

A travel limiter for a hydraulic booster according to the present invention comprises a power piston slidably fitted in a cylinder of a housing and a power piston provided behind the power piston in the housing. A pressure chamber, an input rod whose tip is slidably fitted in a hole formed on the back surface of the power piston, and a spool valve that switches a flow path during operation to supply and discharge hydraulic fluid to the power pressure chamber. ,
A hydraulic booster provided with a lever that operatively connects the power piston, the input rod, and the spool valve.The hydraulic booster includes a passage hole formed in a distal end portion of the input rod, and a passage hole fixed in the passage hole. A cylindrical member having a valve seat formed on the inner surface, and housed in the cylindrical member,
A valve body that is biased by a spring and can be seated on the valve seat, and a plunger that pushes up the valve body and separates the valve body from the valve seat, and between a chamber in a hole of the power piston and a power pressure chamber. The communication can be interrupted, and a damper for absorbing the movement of the valve body is provided.

According to a third aspect of the present invention, there is provided a travel limiter, wherein a throttle is provided on the chamber side of the cylindrical member with respect to a valve seat.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in the drawings. FIG. 1 is a longitudinal sectional view showing a travel limiter of a hydraulic booster according to an embodiment of the present invention. This travel limiter may be applied to the hydraulic booster shown in FIG. Can also be used for hydraulic boosters. Here, the same parts as those of the configuration of the hydraulic booster will be denoted by the same reference numerals as those applied to the hydraulic booster of FIG.

A large diameter portion 20a at the tip of the input rod 20 is inserted into a circular hole 8b formed on the rear side of the power piston 8.
Are fitted, and the large-diameter portion 20 of the distal end of the input rod 20
A travel limiter 66 is provided inside a.
The distal end surface of the large diameter portion 20a of the input rod 20 and the large diameter portion 20
Passage holes 20e and 20f are formed to pass obliquely between the stepped portion 20d between the shaft portion 20a and the small diameter shaft portion 20c. The passage holes 20e and 20f are composed of a large-diameter hole 20e on the distal end surface side of the input rod 20 and a small-diameter hole 20f on the step portion 20d side, and a cylindrical member (valve body) is provided in the large-diameter hole 20e.
67 is press-fitted and fixed. A valve seat 67a is formed on the inner surface of the bottom (the side of the small diameter hole 20f) of the cylindrical member 67.

A valve (ball valve) 7 is provided inside the cylindrical member 67.
0 is accommodated and held by the ball retainer 100. A guide member 1 is provided at the opening on the tip end side of the cylindrical member 67.
02 is fixed, and a spring 10 is interposed between the guide member 102 and the ball retainer 100.
4, the ball valve 70 is urged toward the valve seat 67a.

The guide member 102 has a cylindrical protrusion 102a at the center, and a guide hole 102b is formed in the inside. On the other hand, on the guide member 102 side of the ball retainer 100, a guide pin 100a is formed integrally, and this guide pin 100a is
2b is slidably fitted in 2b. When the ball valve 70 moves by being pushed by the plunger 72, the guide pin 100a of the ball retainer 100 slides in the guide hole 102b, thereby guiding the advance and retreat of the ball valve 70 and the ball retainer 100. Ball retainer 100 in guide hole 102b formed in guide member 102
A throttle member 106 having a small-diameter passage 106a is fitted into the opening on the opposite side from the opening. As described above, the guide pin 102a of the ball retainer 100 is inserted into one side (the right side in the drawing) of the guide member 102, and the throttle member 106 is fitted into the other side of the guide hole 102b.
8 are formed.

A plunger (pin for pressing the ball valve 70) 72 is inserted into the small-diameter hole 20f of the passage hole so as to be able to move forward and backward, and usually the plunger 72 pressed by the intermediate plate 60 is a ball valve. By pushing up 70, the power pressure chamber 32 communicates with the chamber 74 in the circular hole 8 b formed in the power piston 8.

In the travel limiter 66, the ball valve 70 is open in the intermediate load state, but when an input exceeding the full load point is applied, the input rod 20 moves forward relative to the lever 46, The plate 60 is the input rod 2
Move away from the 0 step 20d. Then, the plunger 72 that has pushed up the ball valve 70 retreats to the right in the drawing, the ball valve 70 is seated on the valve seat 67a in the cylindrical member 67, and the chamber 74 inside the power piston 8 is changed to the power pressure chamber 32. And sealed. When the internal chamber 74 is thus sealed, the input of the input rod 20 is directly transmitted to the power piston 8.

When the brake pedal is released, the input rod 20 moves backward, the plunger 72 is pushed up again by the intermediate plate 60, and the ball valve 70 is opened. In the conventional travel limiter 66, when the pedal is repeatedly depressed and returned suddenly, the opening and closing of the ball valve 70 is repeated to vibrate and generate abnormal noise. However, in the travel limiter 66 according to this embodiment, Since the vibration of the ball valve 70 is absorbed by the damper chamber 106, generation of abnormal noise due to the vibration can be prevented.

FIG. 2 shows a travel limiter 66 according to a second embodiment. In this example, a cylindrical member 67 is provided.
The spring 104 interposed between the retainer 109 fitted in the opening of the ball valve 70 and the ball valve 70 allows the ball valve 7 to be mounted.
0 is urged toward the valve seat 67a. Further, on the inner surface of the cylindrical member 67, a reduced diameter portion 67b is formed adjacent to a valve seat 67a formed near the small diameter hole 20f,
A throttle 1 is provided between the reduced diameter portion 67b and the outer periphery of the ball valve 70.
12 are formed. The reduced diameter portion 67b on the inner surface of the cylindrical member 67 is provided near the valve seat 67a, and the intermediate plate 60 contacts the stepped portion 20d, and the plunger 72
When the ball valve 70 is pushed up and fully opened, the throttle 112 is released from the reduced diameter portion 67b.

In this configuration, when the ball valve 70 is opened to supply or discharge the liquid to or from the chamber 74 in the hole 8a of the power piston 8, the fluid passage 110 in the seat portion (between the ball valve 70 and the valve seat 67a). The flow is restricted by the gap between
Furthermore, since the throttle 112 (the gap between the ball valve 70 and the reduced diameter portion 67b) is also throttled, the flow velocity flowing through the seat portion 110 becomes slower than before, so that even when the pedal is suddenly depressed or suddenly returned, the fluid noise is reduced. Can be prevented from occurring. When the ball valve 70 is fully opened after the ball valve 70 is opened, the throttle 112 is released and the flow of the liquid is no longer restricted, so that the supply and discharge of the liquid to the chamber 74 in the hole 8a is performed smoothly.

[0044]

As described above, according to the present invention, a power piston slidably fitted in a cylinder of a housing, a power pressure chamber provided behind the power piston in the housing, An input rod whose tip is slidably fitted in a hole formed on the back surface of the piston, a spool valve that switches a flow path during operation to supply and discharge hydraulic fluid to and from the power pressure chamber, A hydraulic booster having a lever for operatively connecting the input rod and the spool valve is provided with a passage hole formed in the distal end of the input rod, and a valve seat fixed to the passage hole and formed on the inner surface. A cylindrical member, a valve body housed in the cylindrical member and urged by a spring to be seated on the valve seat, and a plunger for pushing the valve body up and away from the valve seat. In a travel limiter capable of shutting off communication between the chamber in the hole of the power piston and the power pressure chamber, the occurrence of abnormal noise due to vibration of the valve body is prevented by providing a damper for absorbing the movement of the valve body. be able to.

According to the third aspect of the present invention,
By providing the throttle on the chamber side of the valve seat of the cylindrical member, it is possible to reduce the flow velocity of the liquid when the valve element is opened, thereby preventing generation of fluid noise.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a travel limiter of a hydraulic booster according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing a travel limiter of a hydraulic booster according to a second embodiment of the present invention.

FIG. 3 is a longitudinal sectional view showing a general hydraulic booster.

FIG. 4 is an enlarged longitudinal sectional view showing a conventional travel limiter.

FIG. 5 is an enlarged longitudinal sectional view showing a conventional charge valve and dump valve.

[Explanation of symbols]

 Reference Signs List 6 housing 8 power piston 8a hole 10 cylinder 20 input rod 20a tip of input rod 20e passage hole 20f passage hole 28 spool valve 32 power pressure chamber 46 lever 66 travel limiter 67 cylindrical member 67a valve seat 70 valve body (ball valve) 72 plunger (Pin) 100 Retainer 100a One end of the retainer (guide pin) 102 Guide member 102a Internal hole 104 Spring 106 Restrictor 108 Damper (damper chamber) 112 Restrictor

Claims (4)

[Claims] 1. A power piston slidably fitted in a cylinder of a housing, a power pressure chamber provided behind the power piston in the housing, and a tip formed in a hole formed in a back surface of the power piston. An input rod fitted slidably, a spool valve for switching a flow path during operation to supply and discharge hydraulic fluid to and from the power pressure chamber, and the power piston;
A hydraulic booster provided with a lever for operatively connecting the input rod and the spool valve, a passage hole formed in a distal end portion of the input rod, and a valve seat fixed to the passage hole and formed on an inner surface. A cylindrical member, a valve body housed in the cylindrical member, urged by a spring, and capable of seating on the valve seat, and a plunger for pushing up the valve body to separate from the valve seat; A travel limiter for a hydraulic booster, wherein a damper for absorbing the movement of the valve body is provided, the travel limiter being capable of shutting off communication between the chamber in the hole and the power pressure chamber. 2. A damper, comprising: a retainer for supporting a valve body; a guide member having an inner hole in which one end of the retainer is slidably fitted; and a flow of hydraulic fluid into the inner hole. The travel limiter for a hydraulic booster according to claim 1, further comprising a restricting member that restricts the travel. 3. A power piston slidably fitted in a cylinder of a housing, a power pressure chamber provided behind the power piston in the housing, and a tip formed in a hole formed in a back surface of the power piston. An input rod fitted slidably, a spool valve for switching a flow path during operation to supply and discharge hydraulic fluid to and from the power pressure chamber, and the power piston;
A hydraulic booster having a lever for operatively connecting the input rod and the spool valve is provided, a passage hole formed in a tip portion of the input rod, and a valve seat fixed to the passage hole and formed on an inner surface. A cylindrical member, a valve body housed in the cylindrical member, urged by a spring, and capable of seating on the valve seat, and a plunger for pushing up the valve body to separate from the valve seat; A travel limiter for a hydraulic booster, wherein a throttle is provided closer to the chamber than a valve seat of the cylindrical member, the travel limiter being capable of shutting off communication between a chamber in the hole and the power pressure chamber. 4. The travel of the hydraulic booster according to claim 3, wherein the throttle is formed by a reduced diameter portion formed on an inner peripheral surface of the cylindrical member and an outer peripheral surface of the valve body. limiter.