JPH0536268B2 - - Google Patents

Description

Detailed Description of the Invention A. Object of the Invention (1) Industrial Field of Application The present invention is directed to inserting front and rear pistons into a cylinder body, and providing a front hydraulic chamber on the front side of the front piston. An assembly of a tandem master cylinder and a hydraulic booster, comprising a tandem master cylinder defining a rear hydraulic chamber between the front and rear pistons, and a hydraulic booster connected to the master cylinder. Regarding.

(2) Prior art The hydraulic booster in the above assembly includes a booster cylinder that is connected to the rear of the cylinder body of a tandem master cylinder, and a booster cylinder that is inserted into the booster cylinder so that the inside thereof is connected to a hydraulic power source. A booster piston that is partitioned into an input hydraulic chamber at the rear and an output hydraulic chamber at the rear with a larger pressure receiving area, and a booster piston that is slidably fitted into a valve hole provided in the booster piston to open the input and output hydraulic chambers. A structure including a valve piston that is manually moved forward and backward so as to communicate with and shut off between the output hydraulic chamber and the oil tank and to shut off and communicate between the output hydraulic chamber and the oil tank is conventionally known.

(3) Problems to be Solved by the Invention In such a conventional assembly, there is a reaction force mechanism that feeds back the operating reaction force of the master cylinder to the valve piston so that the operator can sense the magnitude of the output of the master cylinder. However, when the pressure receiving part of the reaction force mechanism faces the output hydraulic chamber, the following problems occur. That is, when the booster is activated, the pressure in the output hydraulic chamber increases and the booster piston moves forward, thereby increasing the pressure in the hydraulic chamber of the master cylinder. A reaction force is generated before the pressure in the hydraulic chamber of the master cylinder increases, making it impossible to accurately feed back the operation reaction force of the master cylinder to the valve piston, especially in the early stages of operation.

In order to solve this problem, for example, as disclosed in Japanese Unexamined Patent Publication No. 58-26666, a connecting member is used to connect the rear piston of the master cylinder and the input part of the reaction force mechanism provided in the booster piston. A valve piston has already been proposed in which the rear piston functions as a pressure-receiving piston of the reaction force mechanism so that the operating reaction force of the master cylinder can be accurately fed back to the valve piston.

However, in the above-mentioned proposal, the booster piston and the rear piston of the master cylinder are separate bodies and are arranged side by side with a space between them in the front-rear direction, so the device as a whole becomes longer in the front-rear direction. Furthermore, the rear piston of the master cylinder is integrally connected to the input part of the reaction force mechanism built into the booster piston, which slides relative to the booster cylinder, so sliding is likely to become unstable and there is a risk that the sliding surface may be strained. There are other problems.

An object of the present invention is to provide an assembly of a tandem master cylinder and a hydraulic booster that can solve all of the above problems.

B. Structure of the Invention (1) Means for Solving the Problems In order to achieve the above object, the present invention includes inserting front and rear pistons into the cylinder body, and providing a front hydraulic chamber on the front side of the front piston. It also includes a tandem master cylinder defining a rear hydraulic chamber between the front and rear pistons, and a hydraulic booster connected to this master cylinder, and the hydraulic booster is connected to the master cylinder. A booster cylinder is connected to the rear of the cylinder body, and the interior of the booster cylinder is divided into an input hydraulic chamber at the front that is connected to the hydraulic pressure source and an output hydraulic chamber at the rear that has a larger pressure receiving area. and a booster piston that is slidably fitted into a valve hole provided in the booster piston to provide communication and disconnection between the input and output hydraulic chambers, as well as disconnection and communication between the output hydraulic chamber and the oil tank. In an assembly of a tandem master cylinder and a hydraulic booster, the booster piston is integrally connected to the rear of the rear piston of the master cylinder, and the booster piston is integrally connected to the rear of the rear piston of the master cylinder. At least the outer periphery of both front and rear ends of the body is slidably fitted into a cylinder hole formed across the master cylinder and the booster cylinder, and the rear piston has a front surface facing a rear hydraulic chamber of the master cylinder. A reaction mechanism having a pressure receiving piston and transmitting the hydraulic pressure in the rear hydraulic chamber to the valve piston of the booster is provided, and on either side of the opposing surface between the pressure receiving piston and the front piston of the master cylinder, there is provided a The present invention is characterized in that an engaging rod is provided protruding from both ends of the rod, the ends of which are opposed to each other with a predetermined spacing between them.

(2) Effect The structure in which the booster piston is integrally connected to the rear piston of the master cylinder allows the master cylinder and the booster cylinder to be brought closer to each other.

In addition, while adopting this structure in which both pistons are directly connected, by arranging a reaction force mechanism in the rear piston of the master cylinder and having its pressure receiving piston directly facing the rear hydraulic chamber of the master cylinder, the rear hydraulic pressure is reduced. Since the reaction force mechanism can accurately sense the chamber's output oil pressure from the initial stage of master cylinder operation, the operation reaction force of the rear piston is accurately fed back to the valve piston, and the operator can easily sense the magnitude of the master cylinder's output. can be detected more accurately at the initial stage of operation. Furthermore, in the unlikely event that the hydraulic pressure in the brake hydraulic system on the rear hydraulic chamber side fails,
As the rear piston moves forward, the pressure receiving piston of the reaction force mechanism engages with the front piston via the engagement rod, so that the output oil pressure of the front hydraulic chamber is accurately sensed by the reaction force mechanism from the initial stage of operation of the master cylinder. Therefore, the operational reaction force of the front piston is accurately fed back to the valve piston, and the operator can accurately sense the magnitude of the output of the master cylinder from the initial stage of operation, as in the normal state.

Furthermore, at least the front and rear ends of the combined body of the rear piston and the booster piston are slidably fitted into the cylinder holes spanning the master cylinder and the booster cylinder, so that the combined body forms a common cylinder body. It is now possible to slide extremely stably and smoothly over a long span in the axial direction.

(3) Examples Examples 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 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 is composed of a pair of front and rear seat bodies 15, 16 that receive both ends of the rear return spring ₁₂₂ , and a support shaft 17 that is attached to the rear piston ₇₂ and slidably supports the front seat body 15. The support shaft 17 as an engagement rod has an enlarged head 17a that restricts forward movement of the front seat body 15. Therefore, the support shaft 17 is connected to the rear seat body 16 of the front seat body 15.
Although it is allowed to approach the rear piston ₇₂ , the enlarged portion 17a prevents the seat bodies 15 and 16 from moving beyond a certain distance, thereby regulating the maximum distance between the seat bodies 15 and 16. 12 ₂ is given an extension limit.

The above is a conventional configuration, and the hydraulic booster B 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 with 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. Thus, the combined body of the rear piston 7 ₂ and the booster piston 21 is such that the outer peripheries of the front end and the intermediate portion sandwiching the replenishment oil chamber 10 ₂ are slidably fitted into the cylinder hole 1a. The outer periphery of the rear end of the combined body sandwiched between input and output hydraulic chambers 23 and 24, which will be described later, is slidably fitted into the cylinder hole 20a, thereby forming a single cylinder body (i.e., cylinder body 1 and booster cylinder 2
Since it is possible to secure a long span in the axial direction with respect to the joint (0 and the combined body), the sliding movement is extremely stable and smooth. 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 at the rear end 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 opposing end surfaces of the valve piston 26 and the elastic piston 43 is slidably connected to the valve piston 26 and the elastic piston 43 . By these pistons 43, 44, 45,
A reaction force 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 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 way, 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 is connected to the solenoid and the power source 5.
A control switch 52 that closes in conjunction with depression of the brake pedal 28 is inserted into the electric circuit connecting the two. Further, the hydraulic pump 48 is driven by the electric motor 5.
3, and a pressure switch 54 that closes in response to the internal pressure of the pressure accumulator 50 decreasing below a certain value is inserted in the electric circuit connecting the motor 53 and the power source 51. . In addition, 5
5 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 inactive, 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 bushing 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 position of communication with the inlet port 37, the valve piston 26 comes into contact with 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.
_The elastic piston 43 is actuated to compress the elastic piston 43, and a part of the compression force is fed back to the valve piston 26 via the reaction piston 45, and further to the brake pedal 28 via the push rod 27. , 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 oil flows into the hydraulic chambers 8 ₁ and 8 2 through the hydraulic oil chambers 8 1 and 8 ₂ , respectively, and is replenished with hydraulic oil. If excessive replenishment occurs at that time, the excess amount is returned to the oil tank 2 through the relief ports 3 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. 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.

C. Effects of the Invention As described above, according to the present invention, in an assembly of a tandem master cylinder and a hydraulic booster, the booster piston is integrally connected to the rear part of the rear piston of the master cylinder, and the combined body is At least the outer periphery of both front and rear ends is slidably fitted into a cylinder hole formed across the master cylinder and the booster cylinder, and the rear piston is provided with a pressure-receiving pressure-receiving force whose front face faces the rear hydraulic chamber of the master cylinder. a reaction mechanism having a piston and transmitting the hydraulic pressure in the rear hydraulic chamber to the valve piston of the booster;
On one of the facing surfaces of the pressure receiving piston and the front piston of the master cylinder, an engagement rod is provided that protrudes from the other side and has its tips facing each other at a predetermined distance. The structure in which the booster pistons are integrally connected allows the master cylinder and the booster cylinder to be brought closer to each other, and even though the two pistons are directly connected as described above, there is a reaction force mechanism in the rear piston of the master cylinder. By arranging the pressure receiving piston and directly facing the rear hydraulic chamber of the master cylinder, the output hydraulic pressure of the rear hydraulic chamber can be accurately sensed by the reaction force mechanism from the initial stage of operation of the master cylinder. It is no longer necessary to make the force mechanism itself long in the longitudinal direction, and as a result, the entire device and the reaction force mechanism can be made smaller in the longitudinal direction, and the operating reaction force of the rear piston in the master cylinder can be accurately transferred to the valve piston. Feedback allows the operator to accurately sense the magnitude of the output of the master cylinder from the initial stage of operation.

In addition, in the event that the hydraulic pressure of the brake hydraulic system corresponding to the rear hydraulic chamber fails, the pressure receiving piston of the reaction force mechanism engages with the front piston via the engagement rod due to the forward movement of the rear piston. The reaction force mechanism can accurately sense the output hydraulic pressure of the front piston from the initial stage of operation of the front piston. Therefore, the operational reaction force of the front piston in the master cylinder can be accurately fed back to the valve piston to reduce the pressure of the master cylinder. The operator can accurately sense the magnitude of the output from the initial stage of operation, as in the normal state.

Furthermore, the rear piston of the tandem master cylinder is integrally connected to the booster piston of the booster, and at least both the front and rear ends of the combined body are slidably inserted into the cylinder hole spanning the master cylinder and the booster cylinder. By fitting, the combined body can be slid very stably and smoothly over a long span in the axial direction with respect to the common cylinder body.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional side view of a master cylinder and booster assembly showing a first embodiment of the present invention, and FIG. 2 is a similar longitudinal sectional side view showing a second embodiment. B... Hydraulic booster, M... Tandem type master cylinder, R... Reaction force mechanism, 1... Cylinder body, 2... Oil tank, 7 ₁ , 7 ₂ ... Front and rear pistons, 8 ₁ , 8 ₂ ... Front and rear hydraulic chambers, 17... Support shaft as engagement rod, 20... Booster cylinder, 21... Booster piston, 23, 24...
Input and output hydraulic chambers, 25...Valve hole, 26...Valve piston, 44...Pressure receiving piston, 45...Reaction force piston, 48...Hydraulic pump serving as a hydraulic pressure source, 50...
Pressure accumulator as hydraulic pressure source, 52...Control switch, 53
...Electric motor, 60...Communication port, 61...
communication groove.

Claims (1)

[Claims] 1 Place the front and rear pistons 7 ₁ and 7 ₂ into the cylinder body 1.
The front hydraulic chamber 8 ₁ is inserted in the front side of the front piston 7 ₁ , and the front and rear pistons 7 ₁ ,
_7. A tandem type master cylinder M having a rear hydraulic chamber _8.2 defined therebetween, and this master cylinder M.
The booster B consists of a hydraulic booster B that is connected to a booster cylinder 20 that is connected to the rear of the cylinder body 1 of the master cylinder M.
A booster piston 21 is inserted into this booster cylinder 20 and divides its interior into a front input hydraulic chamber 23 connected to hydraulic sources 48 and 50 and a rear output hydraulic chamber 24 having a larger pressure receiving area.
The booster piston 21 is slidably fitted into a valve hole 25 provided in the booster piston 21 for communication and isolation between the input and output hydraulic chambers 23 and 24, and for isolation and isolation between the output hydraulic chamber 24 and the oil tank 2. In an assembly of a tandem master cylinder and a hydraulic booster, the booster piston 21 is integrated with the rear part of the rear piston ₇₂ , and the tandem master cylinder is equipped with a valve piston 26 that is manually moved forward and backward to establish communication. cylinder holes 1a, 20 formed so as to extend over the master cylinder M and the booster cylinder 20 so that at least the outer periphery of both front and rear ends of the combined body extends over the master cylinder M and booster cylinder 20.
The rear piston 7 ₂ has a pressure receiving piston 44 that faces the rear hydraulic chamber _{8 2} so as to be slidably fitted into the valve piston 26 . A reaction force mechanism R is provided to transmit the
A tandem type master characterized in that an engaging rod 17 is provided on one of the facing surfaces of the pressure receiving piston 44 and the front piston ₇₁ , the other end of which is opposed to each other with a predetermined interval. Assembly of cylinder and hydraulic booster.