JPH042454B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic booster, particularly a booster cylinder connected to the rear of the cylinder body of a master cylinder; A booster piston partitioned into an input hydraulic chamber and a rear output hydraulic chamber having a larger pressure-receiving area; a booster piston that slides into a valve hole provided in the booster piston to allow communication and isolation between the input and output hydraulic chambers; The present invention also relates to a hydraulic booster equipped with a valve piston that is manually moved forward and backward to shut off and communicate between the output hydraulic chamber and the oil tank.

In the above type of booster, when retracting the valve piston to disable the master cylinder,
A system in which the retraction forces of the master cylinder piston and booster piston are applied only from return springs provided in relation to these pistons is conventionally known, as disclosed in Japanese Patent Laid-Open No. 57-90249, for example. It is.

However, in such conventional valves, if the set load of the return spring that applies a retracting force to the piston of the master cylinder and the booster piston is set relatively large, there is a problem that the responsiveness of the master cylinder to the forward movement of the valve piston is reduced. Yes, on the other hand, if the above set load is set relatively small,
Although the above problem was solved, there was another problem in that each piston could not be smoothly retracted due to the relatively large sliding resistance that each piston received from the cylinder via the seal member.

Therefore, the pressure receiving area on the front side of the booster piston in the input hydraulic chamber is set larger than the pressure receiving area on the rear side of the same piston, and by using the hydraulic pressure in the input hydraulic chamber when the valve piston retreats, a retreating force is applied to the booster piston. A system in which the booster piston and the master cylinder piston are movable relative to each other in the longitudinal direction has already been proposed (for example, see Japanese Patent Application Laid-Open No. 58-26666). As mentioned above, the retraction force applied to the booster piston using the hydraulic pressure in the input hydraulic chamber is not transmitted to the piston of the master cylinder, and therefore the retraction force on the piston of the master cylinder still comes only from the dedicated return spring. The same problem as mentioned above arises when setting the set load of the return spring.

The present invention has been proposed in view of the above, and is capable of quickly retracting both the piston of the master cylinder and the booster piston, even if the set load of the return spring of the piston in the master cylinder is set relatively weak. It is an object of the present invention to provide a hydraulic booster capable of increasing the responsiveness of a master cylinder to a retreating operation of a valve piston.

In order to achieve this purpose, the present invention
A booster cylinder connected to the rear of the cylinder body of the master cylinder; a front input hydraulic chamber that is slid into the booster cylinder and whose interior is connected to a hydraulic pressure source; and a rear output hydraulic chamber that has a larger pressure-receiving area. a booster piston that is partitioned into; a booster piston that is slid into a valve hole provided in the booster piston to provide communication and isolation between the input and output hydraulic pressure chambers, as well as isolation and communication between the output hydraulic pressure chamber and the oil tank; In a hydraulic booster, the booster piston is integrally connected to a piston of a master cylinder, and the rear surface of the piston of the master cylinder is made to face the input hydraulic pressure chamber. , characterized in that the pressure receiving area of the booster piston in the input hydraulic chamber is larger than the pressure receiving area of the piston of the master cylinder in the same chamber.

Embodiments of the present invention will be described below with reference to the drawings. First of all, starting with the first embodiment shown in FIG. 1, M is a tandem type master cylinder for a two-system hydraulic brake of an automobile, and an oil tank 2 is formed on the upper side of the cylinder body 1, and the inside thereof is formed on the lower side. The half part is divided by a partition wall 2a into a front oil sump 2 ₁ and a rear oil sump 2 ₂ , and these oil sumps 2 ₁ and 2 ₂ are connected to front relief ports 3 ₁ and 3 ₂ and rear supply ports, respectively. It communicates with the cylinder hole 1a of the cylinder body 1 via 4 ₁ and 4 ₂ . A front piston 7 ₁ and a rear piston 7 ₂ are slid into the cylinder hole 1a.

In the cylinder hole 1a, a front hydraulic chamber ₈₁ is formed between the front piston ₇₁ and the front end wall of the cylinder hole 1a.
Further, a rear hydraulic chamber 8 ₂ is defined between both pistons 7 ₁ and 7 ₂ , and these hydraulic chambers 8 ₁ and 8 ₂ communicate with each of the two brake hydraulic circuits via output ports (not shown), respectively. Each piston 7 ₁ , 7 ₂ is provided with a piston cup 9 ₁ , 9 ₂ at the front end, respectively,
Further, annular replenishment oil chambers 10 ₁ and 10 ₂ are formed on the outer periphery of the intermediate portion with a small diameter, and through holes 11 1 communicate these oil chambers 10 ₁ and 10 ₂ with the backs of the piston cups 9 ₁ and 9 _{2 .} , 11 ₂ for each piston 7 ₁ ,
7 Provided at the front end of ₂ .

The hydraulic chamber 8 ₁ accommodates the return spring 12 ₁ that urges the front piston 7 ₁ in the backward direction, and the rear oil chamber 8 ₂ houses the rear return spring 12 ₂ that urges the rear piston 7 ₂ in the backward direction. and a spacing device 14 that limits the expansion of the spring beyond a certain level. The spacing device 14 includes a pair of front and rear movable and fixed seats 15, which receive both ends of the rear return spring ₁₂₂ .
16, and a support shaft 17 that is attached to the rear piston ₇₂ and slidably supports the movable seat body 15, and the support shaft 17 has an enlarged head 17a that restricts the forward movement of the movable seat body 15. are doing. Therefore,
The support shaft 17 allows the movable seat body 15 to approach the rear piston 7 ₂ , but prevents the movable seat body 15 from moving beyond a certain distance from the rear piston _{7 2} by the enlarged portion 17 a. The maximum distance between the return springs 12 2 is regulated, and the extension limit is given to the return spring 12 ₂ by this regulation.

The above is a conventional configuration, and the hydraulic booster BB of the present invention is connected to this master cylinder M. The configuration of the booster B will be explained next.

A cylinder hole 20a having a larger diameter than the cylinder hole 1a is provided at the rear of the cylinder body 1 of the master cylinder M.
A booster cylinder 20 having a diameter is integrally connected to the booster cylinder 20, and a booster piston 21 that slides into the cylinder hole 20a is integrally connected to the rear part of the rear piston ₇₂ . An end plug 22 that restricts the backward limit of the booster piston 21 is screwed onto the rear end of the booster cylinder 20 .

In the cylinder hole 20a, the booster piston 21 has a small diameter in the intermediate portion, defines an annular input hydraulic pressure chamber 23 on its outer circumference, and defines an output hydraulic chamber 24 between the end plug 22 and the output hydraulic pressure. The pressure receiving area of the chamber 24 is larger than that of the input hydraulic pressure chamber 23. Also, due to the difference in size between the cylinder holes 1a and 20a, the rear piston 7 ₂ in the input hydraulic chamber 23
The pressure receiving area S ₂ of the booster piston 21 is larger than the pressure receiving area S ₁ of the booster piston 21 .

The rear piston 7 ₂ and the booster piston 21 have a booster piston 21 along their axes.
A series of valve holes 25 are drilled starting from the rear end and ending in the middle of the rear piston 7 ₂ .
5, a valve piston 26 that passes through the end plug 22 is slidably engaged with the valve piston 26, and a brake pedal 28 is connected to the rear end of the valve piston 26 via a push rod 27.

An annular recess 2 is provided on the rear end surface of the booster piston 21.
9 is formed, and a stopper ring 30 is fixed to the opening of the recess 29, and a stopper ring 31 that comes into contact with the stopper ring 30 within the recess 29 to restrict the backward limit of the valve piston 26 is fixed to the valve piston 26. be done. The latter stopper ring 31 is urged toward the former stopper ring 30 by a return spring 32. The forward limit of the valve piston 26 relative to the booster piston 21 is regulated by the front end of the valve piston 26 coming into contact with the front end wall of the valve hole 25 .

The valve piston 26 has three annular ports 33, 3 arranged at intervals in the axial direction on its outer periphery.
4, 35, and an oil passage 36 that communicates these ports 33, 34, 35 with each other. Hereinafter, the ports 33, 34, and 35 will be referred to as the front port 33, the center port 34, and the rear port 35 from the front end side of the valve piston 26, and the rear port 3
5 is always open to the output hydraulic chamber 24.

On the other hand, the booster piston 21 has an inlet port 37 extending from the input hydraulic chamber 23 to the valve hole 25 corresponding to the central port 34, and the rear piston ₇₂ has an inlet port 37 corresponding to the central port 34.
Outlet ports 38 extending from the valve hole 25 to the replenishment oil chamber 10 ₂ are bored corresponding to the front ports 33, respectively.

Note that the cylinder hole 2 is connected to the front end of the valve piston 26.
The front oil chamber 39 defined at the front of the valve 0a is communicated with the supply oil chamber 10 ₂ through the through hole 40 of the rear piston 7 ₂ so as not to interfere with the sliding movement of the valve piston 26 .

The rear piston ₇₂ has a large diameter hole 41 that opens at its front surface, and a small diameter hole 42 that opens both ends of the large diameter hole 41 and the cylinder hole 20a. An elastic piston 43 made of rubber or the like and a pressure receiving piston 44 having the same diameter are slid together in order, so that the pressure receiving piston 4
The pressure receiving surface of No. 4 faces the rear hydraulic chamber ₈₂ . Small diameter hole 42
A reaction piston 45 that can come into contact with the opposite end surfaces of the valve piston 26 and the elastic piston 43 is slidably connected to the valve piston 26 . By these pistons 43, 44, 45,
A reaction mechanism R is configured to transmit the actuation reaction force of the rear piston 7 ₂ to the valve piston 26 .

The pressure receiving piston 44 is prevented from coming off from the large diameter hole 41 by a stop ring 46 fixed to the opening of the large diameter hole 41, and the support shaft 17 of the spacing device 14 is mounted on the front surface of the pressure receiving piston 44. It is installed in one piece. In this case, the support shaft 17 and the pressure-receiving piston 44 constitute one part, which is advantageous in terms of simplifying the structure.

The input hydraulic chamber 23 is connected to the oil tank 2 by an oil passage 47.
The oil passage 47 is connected to a hydraulic pump 48 that can pump the oil stored in the oil tank 2 to the input hydraulic chamber 23.
and an electromagnetic on-off valve 49 located downstream of the pump 48 are interposed, and a pressure accumulator 50 is connected between the hydraulic pump 48 and the on-off valve 49.

The electromagnetic on-off valve 49 is a normally closed type that opens when the solenoid is energized, and the electric circuit connecting the solenoid and the power source 51 includes a brake pedal 2.
8, a control switch 52 that closes in conjunction with the depression operation.
is inserted. The hydraulic pump 48 is driven by an electric motor 53, and an electric circuit connecting the motor 53 and the power source 51 is configured to respond to the decrease in the internal pressure of the pressure accumulator 50 below a certain value. A closing pressure switch 54 is inserted.
Note that 55 is a main switch that is linked to the opening and closing of the ignition switch of the automobile.

Next, the operation of this embodiment will be explained. When the main switch 55 is first closed in conjunction with the closing operation of the car's ignition switch, the electric motor 53 is activated to drive the hydraulic pump 48, allowing the accumulator 50 to accumulate hydraulic pressure up to a predetermined pressure. can.

When the brake pedal 28 is not operated, the control switch 52 is open as shown in the figure, so the electromagnetic on-off valve 49 is closed. Further, the valve piston 26 is held at the retracting limit by contact between the two stopper rings 30 and 31, the front port 33 occupies a position communicating with the outlet port 38, and the central port 33 is in communication with the outlet port 38.
4 occupies a slightly rearward position so as to be blocked from the inlet port 37. Therefore, the output hydraulic pressure chamber 24 communicates with the oil tank 2 via the rear port 35, oil passage 36, front port 33, outlet port 38, replenishment oil chamber 10 ₂ and supply port 4 ₂ and is brought to atmospheric pressure. Therefore, the front and rear pistons 7 ₁ , 7 ₂ and the booster piston 21 each have a return spring 12
It is held in the retracted position by a force of ₁ , 12 ₂ .

Now, to brake the car, press the brake pedal 28.
When the user depresses the button, the control switch 52 is closed and the on-off valve 49 is opened. At the same time brake pedal 28
from the valve piston 26 via the push rod 27.
is pushed forward, first cutting off the front port 33 from the outlet port 38 and then moving the central port 34 into communication with the inlet port 37. As a result, the hydraulic pressure is supplied from the pressure accumulator 50 and the hydraulic pump 48 to the input hydraulic chamber 23, and the hydraulic pressure is supplied to the output hydraulic chamber 24 through the inlet port 37, the central port 34, the oil passage 36, and the rear port 35. Therefore, booster piston 2 receives the oil pressure.
1 moves forward, which causes the front and rear pistons 7 ₁ ,
7 ₂ is advanced while compressing their return springs 12 ₁ and 12 ₂ . At this time, if both brake hydraulic circuits are normal, each piston cup 9
₁ , 9 ₂ pass through the relief ports 3 ₁ , 3 ₂ , and then the respective hydraulic chambers 8 1 , 9 ₂ open in response to the advance of each piston 7 ₁ , 7 ₂ .
It is possible to generate hydraulic pressure in 8 ₂ and operate both brake hydraulic circuits at the same time.

During this braking process, when the central port 34 reaches the communication position with the inlet port 37, the valve piston 26 abuts the elastic piston 43 via the reaction piston 45. Then, as the rear piston 7 ₂ moves forward, the oil pressure in the rear hydraulic chamber 8 ₂ increases.
The pressure receiving piston 44 transfers the hydraulic pressure to the rear piston 7.
₂ , and a portion of the compression force is fed back to the valve piston 26 via the reaction piston 45, and further via the push rod 27 to the brake pedal 28, This allows the driver to sense the magnitude of the braking force. In this case, especially the pressure receiving piston 44 is the hydraulic chamber 8 of the master cylinder M.
Since it directly senses the hydraulic pressure of ₂ , the master cylinder M
It is possible to accurately sense the magnitude of the output from the initial stage of operation.

During this braking, if there is an oil leakage failure only in the brake hydraulic circuit on the front hydraulic chamber 8 ₁ side, no oil pressure will naturally be generated in the front hydraulic chamber 8 ₁ even though the front piston 7 ₁ moves forward. The forward stroke of the booster piston 21 until the front piston ₇₁ comes into contact with the front end wall of the cylinder hole 1a becomes an invalid stroke, but the subsequent forward movement of the booster piston 21 generates hydraulic pressure in the rear hydraulic chamber ₈₂ . can be done.

On the other hand, if there is an oil leakage failure only in the brake hydraulic circuit on the rear hydraulic chamber 8 ₂ side, no oil pressure will naturally be generated in the rear hydraulic chamber 8 ₂ even if the rear piston 7 ₂ moves forward. 14 supporting shafts 17
The forward stroke of the booster piston 21 until it comes into contact with the rear end of the front piston 7 ₁ becomes an invalid stroke, but the subsequent advancement of the booster piston 21 advances the front piston 7 ₁ via the support shaft 17. Hydraulic pressure can be generated in the front hydraulic chamber ₈₁ . At this time, since the actuation reaction force of the front piston ₇₁ is transmitted to the pressure receiving piston 44 via the support shaft 17, this force can be fed back to the brake pedal 28 in the same manner as described above.

Next, when the brake pedal 28 is released to release the brake, the valve piston 26 is moved back by the force of the return spring 32, and the center port 34 is connected to the inlet port 37, as in the non-operating state described above. Since the front port 33 is returned to the blocking position and the position communicating with the outlet port 38, the hydraulic pressure in the output hydraulic chamber 24 is released to the oil tank 2. On the other hand, while the on-off valve 49 is open, hydraulic pressure continues to be introduced into the input hydraulic chamber 23, so this hydraulic pressure is applied to the pressure receiving area difference (S2) between the rear piston ₇₂ and the booster piston 21 in the input hydraulic chamber ₂₃ . −S ₁ ) to act on the booster piston 21
gives a retreating force to. As a result, the booster piston 21 follows the backward motion of the brake pedal 28, and in conjunction with this, the front and rear pistons 7 ₁ and 7 ₂ move backward by the force of the return springs 12 ₁ and 12 ₂ . When the booster piston 21 reaches its backward limit and the brake pedal 28 returns to its initial non-operating position, the control switch 52 is opened, and the on-off valve 49 is closed to shut off the oil passage 47.

During this time, if pressure is reduced in the hydraulic chambers 8 _{1 , 8 2 due to the backward movement of both pistons 7 1 , 7 2} , the outer peripheries of the piston cups 9 ₁ , 9 ₂ will bend forward due to the pressure difference between the front and rear ends of the piston cups 9 1 , 9 2 . A gap is created between the inner surface of the hole 1a and, as a result, the hydraulic oil in the oil reservoirs 2 ₁ , 2 ₂ flows into the supply ports 4 ₁ , 4 ₂ , the replenishment oil chambers 10 ₁ , 10 ₂ and the through holes 11 ₁ , 11 ₂ The hydraulic oil flows into the hydraulic chambers 8 ₁ and 8 _{2 through the hydraulic fluid chambers 8 1 and 8 2} , respectively, and is replenished with hydraulic oil. If excessive replenishment occurs at that time, the excess amount flows into the relief port 3 .
It is returned to oil tank 2 from ₁ and 3 ₂ .

Next, a second embodiment of the present invention shown in FIG. 2 will be described. In addition to the inlet port 37, the booster piston 21 has a communication port 60 extending from the valve hole 25 to the output hydraulic chamber 24 at the rear thereof, and a communication port 60 further behind the inlet port 37. Outlet port 3 leading from the output hydraulic chamber 24 to the valve hole 25
8 is bored in the valve piston 26, and an annular communication groove 61 is provided in the valve piston 26 for communicating and blocking communication between the inlet port 37 and the communication port 60 according to the movement of the piston 26.
and an annular rear port 35 that is shut off and communicated with the outlet port 38 as the piston 26 moves forward and backward.
And this rear port 35 is connected to the front oil chamber 3 of the valve hole 25.
An oil passage 3 that constantly communicates with the replenishment oil chamber 10 ₂ via 9
6 is drilled. Support shaft 17 of spacing device 14
is screwed onto the rear end of the front piston 7 ₁ and connects to the pressure receiving piston 44 that slides on the rear piston 7 ₂ when the distance between the front and rear pistons 7 ₁ and 7 ₂ narrows to a certain value. It's getting old. This support shaft 17
is equipped with an enlarged head 17a at the rear end to restrict the backward movement of the movable seat 15, and a rear return spring ₁₂₂ is compressed between the movable seat 15 and the front piston ₇₁ . be done. Although the valve piston 26 is divided into front and rear parts for manufacturing reasons, it is not necessary to do so. The rest of the structure is the same as that of the previous embodiment, and the same reference numerals are given to the parts corresponding to those of the previous embodiment in the figures.

Therefore, if the valve piston 26 is in the retracted position,
Inlet port 37 is blocked and outlet port 38 is blocked.
Since the rear port 35 is communicated with the input and output hydraulic chambers 23 and 24, the output hydraulic chamber 24 is connected to the outlet port 38, the rear port 35, the oil passage 36, the front oil chamber 39, and the through hole 40. and replenishment oil room 10
It is communicated with the oil tank 2 via ₂ . Also, when the valve piston 26 is moved to the forward position, the outlet port 38
and the rear port 35, and then the communication groove 61 connects the inlet port 37 and the communication port 60.
Since the output hydraulic chamber 24 and the oil tank 2 are communicated with each other,
The space between the input and output hydraulic chambers 23 and 24 is cut off.
These are communicated via the inlet port 37, the communication groove 61, and the communication port 60.

As described above, according to the present invention, the booster piston is integrally connected to the piston of the master cylinder, and the rear surface of the piston of the master cylinder faces the input hydraulic chamber of the booster, and the booster piston in the input hydraulic chamber Since the pressure receiving area of the piston of the master cylinder in the same chamber is made larger than that of the piston of the master cylinder in the same chamber, when the input and output hydraulic chambers are cut off and the hydraulic pressure of the output hydraulic chamber is released to the oil tank by retracting the valve piston, the input hydraulic pressure is By effectively utilizing the oil pressure in the chamber, sufficient retraction force can be applied to the booster piston and the piston of the master cylinder integrally connected to it, thereby reducing the set load of the return spring of the piston in the master cylinder. Even if the valve piston is set relatively weakly, not only the booster piston but also the master cylinder piston can be moved backward quickly against the relatively large sliding resistance that these pistons receive from the cylinder. The responsiveness of the master cylinder to the backward operation of the valve piston can be improved, and the responsiveness of the master cylinder to the forward operation of the valve piston can also be increased by the amount that the set load of the return spring is weakened.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional side view of an assembly of a master cylinder and booster showing a first embodiment of the present invention, and FIG. 2 is a similar longitudinal sectional side view showing a second embodiment. M...Master cylinder, B...Boosting device, R...
...reaction mechanism, S ₁ ... pressure receiving area of the rear piston 7 ₂ in the input hydraulic chamber 23, S ₂ ... pressure receiving area of the booster piston 21 in the input hydraulic chamber, 1 ... cylinder body, 2 ... oil tank, 7 ₁ , 7 ₂ ... Front and rear pistons, 8 ₁ , 8 ₂ ... Front and rear hydraulic chambers, 20...
...Booster cylinder, 21...Booster piston, 23...Input hydraulic chamber, 24...Output hydraulic chamber,
25... Valve hole, 26... Valve piston, 28... Brake pedal, 33... Front port, 34... Center port, 35... Rear port, 36... Oil path,
37...Inlet port, 38...Outlet port, 48
...Hydraulic pump as a hydraulic power source, 50...Pressure accumulator as a hydraulic power source.

Claims (1)

[Claims] 1 A booster cylinder 20 that is connected to the rear of the cylinder body 1 of the master cylinder M; it is slid into this booster cylinder 20 and the inside thereof is connected to a hydraulic power source 4.
A booster piston 21 is partitioned into an input hydraulic chamber 23 at the front connected to 8 and 50 and an output hydraulic chamber 24 at the rear which has a larger pressure receiving area; and a valve piston 26 that is manually operated to move forward and backward so as to communicate and disconnect between the input and output hydraulic chambers 23 and 24, and to disconnect and communicate between the output hydraulic chamber 24 and the oil tank 2. In the type booster, the booster piston 21 is integrally connected to the piston 7 ₂ of the master cylinder M, and the rear surface of the piston 7 ₂ of the master cylinder M faces the input hydraulic chamber 23 . The pressure receiving area S ₂ of the booster piston 21 in the same chamber 2
The piston ₇ of the master cylinder M in 3 2
A hydraulic booster characterized by having a pressure receiving area larger than _S1 .