JPH04864B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic booster used for hydraulically boosting a master cylinder for operating a hydraulic brake of an automobile, for example.

Conventionally, this type of hydraulic booster has been provided with its own oil reservoir, which has caused the problem of increasing the size of the entire device.

The present invention was proposed in view of this problem, and has a simple and compact structure by being integrated with the master cylinder to form a unit, and by making it possible to share the oil tank originally provided with the master cylinder. It is an object of the present invention to provide the above-mentioned hydraulic booster.

To achieve this objective, according to the present invention, a hydraulic booster includes a booster cylinder integrally connected to the rear part of a cylinder body of a master cylinder having an oil tank in the upper part; and a suction port communicating with the oil tank. a hydraulic pump; the booster cylinder is slidably fitted into the booster cylinder and its interior is divided into a front input hydraulic chamber connected to the discharge port of the hydraulic pump, and a rear output hydraulic chamber having a larger pressure receiving area; A booster piston is integrally connected to the rear part of the master piston of the cylinder; the booster piston slides into a valve hole provided from the rear part of the booster piston to the middle part of the master piston, and penetrates the output hydraulic chamber to be moved forward and backward. a valve piston; the master piston defines an annular replenishment oil chamber communicating with the oil tank between the inner wall of the cylinder body;・Providing an inlet side that communicates and blocks communication between the input hydraulic chamber and the output hydraulic chamber by retreating, and an outlet valve that similarly blocks and communicates between the output hydraulic chamber and the supply oil chamber by moving the valve piston forward and backward. It is characterized by

An embodiment of the present invention will be described below with reference to the drawings. 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 of the cylinder is divided into a front oil tank ₂₁ and a lower half by a partition wall 2a. Rear oil sump 2 ₂
These oil reservoirs 2 ₁ and 2 ₂ communicate with the cylinder hole 1a of the cylinder body 1 through the front relief ports 3 ₁ and 3 ₂ and the rear supply ports 4 ₁ and 4 ₂ , respectively. There is. A front piston 7 ₁ and a rear piston 7 ₂ (master piston) 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 101 and 10 ₂ are formed on the outer periphery of the intermediate portion with a small diameter, and through holes 11 ₁ and 10 ₂ are formed to communicate the oil chambers 10 ₁ and 10 2 with the backs of the piston cups 9 ₁ and 9 ₂ , respectively. 11 ₂ is each piston 7 ₁ ,
7 Provided at the front end of ₂ .

The front hydraulic chamber 8 ₁ accommodates a front return spring 12 ₁ that urges the front piston 7 ₁ in the backward direction, and the rear oil chamber 8 ₂ accommodates a rear return spring 12 1 that urges the rear piston 7 ₂ in the backward direction. 12 ₂ and a spacing device 14 that limits the extension 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 coming closer than a certain distance from the rear piston 7 ₂ with 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 B of the present invention is connected to this master cylinder M.
These are unitized. 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 cylindrical shape is integrally connected to the rear piston ₇₂ , 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 of the booster piston 21 is larger than that 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 ₇₂ into which a valve piston 26, which passes through the end plug 22, slides. A brake pedal 28 is connected to the rear end via a bushing rod 27.

The end plug 22 has a valve piston 2 attached thereto.
6. A retainer plate 30 for holding the seal member 29 in contact with the outer periphery is fitted from the output hydraulic chamber 24 side, and a stopper flange 31 contacts the retainer plate 30 to restrict the backward limit of the valve piston 26.
is formed in the middle portion of the valve piston 26. A small oil chamber 32 is defined in the front part of the valve hole 25 by the front end surface of the valve piston 26, and a return spring 33 for urging the valve piston 26 in the backward direction is contracted in the small oil chamber 32. .

The forward limit of the valve piston 26 relative to the booster piston 21 is such that the front end of the valve piston 26 is in the small oil chamber 32.
It is regulated by contacting the front end wall of the

The valve piston 26 has an annular front port 34 and a rear port 35 which are arranged at a distance from each other on the outer periphery of the valve piston 26 and communicate with each other. An oil passage 36 communicating with the rear port 35 is provided.
is always open to the output hydraulic pressure chamber 24.

On the other hand, the booster piston 21 has an inlet port 37 leading from the input hydraulic chamber 23 to the valve hole 25 corresponding to the front port 34, and the rear piston ₇₂ has an inlet port 37 corresponding to the front end edge of the valve piston 26. , valve hole 2
5 to the replenishment oil chamber 10 ₂
are drilled respectively. Therefore, input port 37
The front port 34 constitutes an inlet valve Vi that opens and closes in accordance with the advance and retreat of the valve piston 26, and the outlet port 38 and the front end edge of the valve piston 26 constitute an inlet valve Vi that opens and closes in accordance with the advance and retreat of the valve piston 26. Outlet valve that closes and opens
Configure Vo.

The valve piston 26 has front and rear ports 34 and 35.
a spool portion 26a having a stopper flange 31, and a rod portion 26 having a stopper flange 31 and supported by the end plug 22.
The two parts 26a and 26b are always kept in contact with each other by the elastic force of the return spring 33.

The input hydraulic chamber 23 is connected to the oil tank 2 of the master cylinder M by an oil passage 40, and the oil passage 40 includes:
A hydraulic pump 41 capable of pumping the oil stored in the oil tank 2 to the input hydraulic chamber 23 and an electromagnetic on-off valve 42 located downstream of the pump 41 are interposed, and pressure is accumulated between the hydraulic pump 41 and the on-off valve 42. device 43 is connected.

The electromagnetic on-off valve 42 is a normally closed type that opens when the solenoid is energized, and the electric circuit connecting the solenoid and the power source 44 includes a brake pedal 2.
A control switch 45 that closes in conjunction with the depression operation of step 8.
is interposed. Further, the hydraulic pump 41 is driven by an electric motor 46, and the electric circuit connecting the motor 46 and the power source 44 is configured to respond to the decrease in the internal pressure of the pressure accumulator 43 below a certain value. A closing pressure switch 47 is inserted.
Note that 48 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 48 is first closed in conjunction with the closing operation of the car's ignition switch, the electric motor 46 is activated to drive the hydraulic pump 41 and accumulate hydraulic pressure in the accumulator 43 to a predetermined pressure. can.

When the brake pedal 28 is inactive, the control switch 45 is open as shown in the figure, so the electromagnetic on-off valve 42 is closed. Further, the valve piston 26 is held at the backward limit by the stopper flange 31 coming into contact with the retainer plate 30, and the front port 34 occupies a position slightly forward of the inlet port 37 so as to be cut off from it. The front end edge of the outlet port 38 is opened half-open to allow communication between the port 38 and the small oil chamber 32.
Therefore, the output hydraulic pressure chamber 24 communicates with the oil tank 2 via the rear port 35, the oil passage 36, the small oil chamber 32, the outlet port 38, the replenishment oil chamber 10 ₂ and the supply port 4 ₂ and is brought to atmospheric pressure. Therefore, the front and rear pistons 7 ₁ and 7 ₂ and the booster piston 21 are held in the retracted position by the force of the return springs 12 ₁ and 12 ₂ , respectively.

Now, to brake the car, press the brake pedal 28.
When the user depresses the button, the control switch 45 is closed and the on-off valve 42 is opened. At the same time brake pedal 28
from the valve piston 26 via the push rod 27.
is forced forward, first the front edge of the valve piston 26 blocking the outlet port, and then the front port 34 is moved into communication with the inlet port 37. As a result, hydraulic pressure is introduced into the input hydraulic chamber 23 from the pressure accumulator 43 and the hydraulic pump 41, and the hydraulic pressure is supplied to the output hydraulic chamber 24 through the inlet port 37, the front port 34, the oil passage 36, and the rear port 35. The booster piston 21 moves forward in response to the oil pressure, which causes the front and rear pistons 7 ₁ ,
7 ₂ is advanced while compressing their return springs 12 ₁ and 12 ₂ . After each piston cup 9 ₁ , 9 ₂ passes through the relief port 3 ₁ , 3 ₂ , each hydraulic chamber 8 corresponds to the advance of each piston 7 ₁ , 7 ₂ .
Hydraulic pressure is generated at ₁ and 8 ₂ , allowing both brake hydraulic circuits to operate simultaneously.

The hydraulic pressure introduced into the output hydraulic chamber 24 also acts as a reaction force that presses the valve piston 26 in the backward direction, and this reaction force is also fed back to the brake pedal 28 via the push rod 27, thereby causing The driver can sense the magnitude of the braking force. In this case, the boost ratio is the piston 7 in each hydraulic chamber 8 ₁ , 8 ₂ of the master cylinder M.
It is determined by the ratio of the pressure-receiving area S ₁ of _{1,7 2} and the cross-sectional area S ₂ of the rod portion 26b of the valve piston 26, so when the valve piston 26 is divided into two as shown in the example shown, the rod portion There is an advantage that the boost ratio can be changed by simply replacing 26b with one of a different diameter. Therefore, if there is no need to change the boost ratio, the valve piston 26 may be an integral type.

Next, when the brake pedal 28 is released to release the brake, the valve piston 26 is moved backward by the force of the return spring 32, and the front port 34 is connected to the inlet port 37 as in the non-operating state described above. The front end edge of the valve piston 26 is placed in the shutoff position of the small oil chamber 32.
Since the output hydraulic pressure chamber 24 is returned to the position where it communicates with the outlet port 38, the hydraulic pressure of the output hydraulic chamber 24 is transferred to the rear port 35, the oil passage 36,
The oil is discharged into the oil tank 2 through the small oil chamber 32, the outlet port 38, the replenishment oil chamber 10 ₂ and the supply port 4 ₂ .

On the other hand, while the on-off valve 42 is open, oil pressure continues to be introduced into the input oil pressure chamber 23, so this oil pressure acts on the difference in pressure receiving area between the rear piston ₇₂ and the booster piston 21 in the input oil pressure chamber 23. to apply a retraction force to the booster piston 21. As a result, the booster piston 21 is connected to the brake pedal 28.
The front and rear pistons 7 ₁ , 7 2 follow the backward movement of the pistons 7 1 , 7 ₂ and move backward by the force of the return springs 12 ₁ , 12 ₂ . When the booster piston 21 reaches its backward limit and the brake pedal 28 returns to its original non-operating position, the control switch 45 is opened, and the on-off valve 42 is closed to cut off the oil passage 40.

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 .

As described above, the hydraulic booster for a master cylinder of the present invention includes: a booster cylinder that is integrally connected to the rear part of the cylinder body of the master cylinder having an oil tank in the upper part; and a hydraulic pump that communicates the suction port with the oil tank. and; the booster cylinder is slidably fitted into the booster cylinder and its interior is divided into a front input hydraulic chamber connected to the discharge port of the hydraulic pump and a rear output hydraulic chamber having a larger pressure receiving area; A booster piston integrally connected to the rear part of the master piston; a valve that slides into a valve hole provided from the rear part of the booster piston to the middle part of the master piston, and penetrates the output hydraulic chamber to be moved forward and backward; a piston; the master piston defines an annular replenishment oil chamber communicating with the oil tank between the inner wall of the cylinder body, and a space between the booster piston and the valve piston due to the advance and retreat of the valve piston. An inlet valve that communicates and blocks communication between the input oil pressure chamber and the output oil pressure chamber, and an outlet valve that also cuts off and communicates between the output oil pressure chamber and the replenishment oil chamber by advancing and retracting the valve piston,
By integrating the master piston and the booster piston, the length of their mutual support can be increased, allowing them to slide smoothly inside the cylinder body and the booster cylinder. This becomes a return oil passage connected to the outlet valve, and therefore no external piping is required for the return oil passage, so that the structure can be simplified by integrating the master piston and the booster piston. Furthermore, by integrating the master piston and booster piston and fitting the valve piston across both pistons, the inlet valve and outlet valve can be distributed to the booster piston side and the master piston side. Therefore, without making the booster piston long, the distance between the inlet valve and the outlet valve can be set sufficiently large to suppress hydraulic leakage between the two valves, and as a result, the axial direction of the booster can be shortened. I can do it.

[Brief explanation of drawings]

The drawing is a longitudinal sectional side view showing one embodiment of the present invention. B... Boost device, M... Master cylinder, Vi
...Inlet valve, Vo ...Outlet valve, 1 ... Cylinder body, 2 ... Oil tank, 4 ₂ ... Supply port, 7 ₂ ...
...rear piston as master piston, 10 ₂
...Replenishment oil chamber, 20...Booster cylinder, 21
... Booster piston, 23 ... Input hydraulic chamber, 2
4... Output hydraulic chamber, 25... Valve hole, 26... Valve piston, 32 Small oil chamber, 39... Outlet port, 41
... Hydraulic pump, 4 ₂ , 10 ₂ , 32, 38 ... Return oil path.

Claims (1)

[Claims] 1. A booster cylinder 20 integrally connected to the rear part of the cylinder body 1 of a master cylinder M having an oil tank 2 at the top; A hydraulic pump 41 whose suction port communicates with the oil tank 2; The interior thereof is divided into a front input hydraulic chamber 23 connected to the discharge port of the hydraulic pump 41 and a rear output hydraulic chamber 24 having a larger pressure receiving area.
₂ Booster piston 21 connected integrally to the rear part
and; a valve piston 26 that slides into a valve hole 25 provided from the rear of the booster piston 21 to an intermediate portion of the master piston ₇₂ and penetrates the output hydraulic chamber 24 to be moved forward and backward; The master piston 7 ₂ defines an annular replenishment oil chamber 10 ₂ communicating with the oil tank 2 between the inner wall of the cylinder body 1 and the booster piston 2 .
1 and the valve piston 26, there is an inlet valve Vi that communicates and shuts off the input hydraulic pressure chamber 23 and the output hydraulic chamber 24 by moving the valve piston 26 forward and backward, and also connects and disconnects the output hydraulic pressure by moving the valve piston 26 forward and backward. A hydraulic booster for a master cylinder, characterized in that it is provided with an outlet valve Vo that blocks and communicates between the chamber 24 and the supply oil chamber ₁₀₂ .