JPH0818548B2 - Tandem negative pressure booster - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention (1) Field of Industrial Application The present invention provides a booster shell with a partition plate partitioning the interior thereof into a front shell chamber and a rear shell chamber. A rear booster piston that divides the rear shell chamber into a front negative pressure chamber and a rear working chamber is fixed to a valve cylinder supported by a rear wall so as to be slidable back and forth. The output rod is connected to the output rod.A front booster piston that divides the front shell chamber into a front negative pressure chamber and a rear working chamber is connected to the output rod, and both negative pressure chambers are connected to a negative pressure source. , A tandem type negative pressure valve provided with an input rod that can be moved back and forth and a control valve that switches both working chambers to the atmosphere and both negative pressure chambers according to the forward and backward movement of the input rod. Regarding boosters.

(2) Conventional Technology A negative pressure booster of this type is already known, as disclosed, for example, in Japanese Utility Model Publication No. 60-10231.

(3) Problems to be Solved by the Invention In the conventional tandem-type negative pressure booster, the output piston of the reaction mechanism fitted to the output rod is slidably slidably engaged with the boss of the front booster piston and the valve cylinder. Therefore, when a large tilting moment is applied to the valve cylinder by the input of the input rod, such as when the output of the output rod exceeds the boost limit point, the front booster piston and the output rod are transmitted from the valve cylinder via the output piston. There is a problem that a large twisting force is applied, which increases the frictional resistance of the sliding parts of each part and causes an input loss.

The present invention has been made in view of the above circumstances, and an object thereof is to provide the tandem-type negative pressure booster in which a twisting force is not generated in each part even when a tilting moment is applied to the valve cylinder.

B. Structure of the Invention (1) Means for Solving the Problems In order to achieve the above object, according to the present invention, a cylinder shaft projecting from the rear surface of the front booster piston is provided on the front end surface of the valve cylinder. It is loosely inserted in the open guide hole, and on the outer peripheral surface of the cylinder shaft,
A pair of protruding ridges are provided so as to sandwich the annular seal member in contact with the inner peripheral surface of the guide hole, and the cylindrical shaft is guided by sliding the seal member and the protruding ridge on the inner peripheral surface of the guide hole. The reaction force mechanism is supported so as to be swingable with respect to the hole, and the reaction force mechanism is closely fitted to a cylinder hole opened at the front end face of the valve cylinder, and an elastic piston with which the input rod can come into contact when moving forward, and a front face of the elastic piston. And an output piston fixed to the rear end of the output rod, the output piston being
The output rod is loosely fitted in the cylinder hole so that it can swing around the valve cylinder.

(2) Operation According to the above configuration, when a tilting moment is applied to the valve cylinder, the valve cylinder, the front booster piston, and the output rod swing slightly each other, so that the tilting moment is absorbed. It is possible to prevent a twisting force from being generated in each part.

Further, in particular, since the seal member placed between the cylinder shaft and the guide hole is located at the swing fulcrum of the cylinder shaft with respect to the guide hole, the seal member is locally moved even when the cylinder shaft swings. There is no risk of receiving an excessive compressive load, and the cylindrical shaft and the guide hole are accurately sealed for a long period of time.

(3) Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, a brake master cylinder M operated by the booster B is mounted on the front surface of the booster shell 1 of the tandem type negative pressure booster B.

The booster shell 1 includes a pair of front and rear shell halves 1a and 1b for connecting opposing ends to each other, and is sandwiched between the two shell halves 1a and 1b to divide the inside of the booster shell 1 into a front shell chamber 2 and a rear shell chamber. The rear shell half 1b is supported by a vehicle body (not shown).

The front shell chamber 2 has a front booster piston 4 housed therein so as to be able to reciprocate back and forth, and a front diaphragm that is superposed on the rear surface of the front booster piston 4 and is sandwiched between the front shell half body 1a and the partition plate 1c. 5, the negative pressure chamber 2a on the front side and the working chamber 2b on the rear side are partitioned from each other, and the rear shell chamber 3 is accommodated in the rear booster piston 6 which can be reciprocally moved back and forth, and the superposed binding on the rear surface thereof. And the rear diaphragm 7 fixed between the shell halves 1a and 1b, the front negative pressure chamber
It is partitioned into 3a and a rear working chamber 3b.

A valve cylinder 8 made of synthetic resin is fixed to the central portion of the rear booster piston 6, and the valve cylinder 8 is slidably supported on the partition plate 1c via a bush 9 and a seal member 10.
Further, the rear extension cylinder 11 of the rear shell half body 1b is slidably supported via a bush 12 and a seal member 13.

The front booster piston 4 is provided with a cylinder shaft 14 whose tip extends rearward, and the cylinder shaft 14 is inserted into a guide hole 15 which is open at the front end surface of the valve cylinder 8. On the outer peripheral surface of the cylinder shaft 14, there are provided an annular groove 17 in which the seal member 16 is mounted, and a pair of protruding ridges 18 and 18 that bulge with the annular groove 17 interposed therebetween. By sliding the strips 18, 18 on the inner peripheral surface of the guide hole 15, the cylinder shaft 14 can be slightly swung while maintaining airtightness with the guide hole 15.

The front negative pressure chamber 2a is connected to a negative pressure source (not shown) (for example, inside the intake manifold of the internal combustion engine) via a negative pressure introducing pipe 19 and also to a rear negative pressure via the first forked port 20 of the valve cylinder 8. It is communicated with the pressure chamber 3a. In addition, both front and rear working chambers 2b and 3b
Are communicated with each other through the second bifurcated port 21 of the valve cylinder 8 and the control valve 22 opens the front and rear negative pressure chambers 2a and 3a and the end wall 11a of the rear extension cylinder 11 to the atmosphere introduction port. It is designed so that communication can be switched alternately to 23 and 23.

An input rod 25 connected to the brake pedal 24 is provided in the valve cylinder 8.
And the control valve 22 controlled thereby is provided as follows. That is, the partition wall 8a formed in the intermediate portion of the valve cylinder 8 is provided with the small cylinder hole 26 opening to the center of the rear surface thereof, and the valve piston 28 is slidably fitted therein. This valve piston
28 has a flange 28a formed on the outer periphery of the intermediate portion, the flange 28a facing a step portion 29 continuing to the open end of the small cylinder hole 26. The front end of the input rod 25 penetrating the atmosphere introducing port 23 is swingably coupled to the valve piston 28.

An annular first valve seat 30 ₁ is formed on the rear surface of the partition wall 8 a, and an annular second valve seat 30 ₂ surrounded by the annular first valve seat 30 ₁ is formed on the valve piston 2
A valve element 31 formed on the rear end surface of the valve 8 and cooperating with the valve seats 30 ₁ and 30 ₂ is disposed in the valve cylinder 8. The valve body 31 is made of rubber and has a tubular shape with both front and rear ends open, and its rear end portion, that is, the base end portion 31 a, is a holding cylinder 32 fitted to the inner peripheral surface of the valve cylinder 8.
Thus, the inner peripheral surface of the valve cylinder 8 is held in a close contact state. The valve body 31 includes a thin flexible portion 31b bent inward in the radial direction from the base end portion 31a, and a thick valve portion 31c connected to the front end of the flexible portion 31b. 31c is arranged so as to face the first and second valve seats 30 ₁ and 30 ₂ .

Thus, the valve portion 31c can be moved back and forth by the deformation of the flexible portion 31b, and is seated on the first and second valve seats 30 ₁ and 30 ₂ when moving forward, and is received by the front end of the holding cylinder 32 when moving backward. Can be stopped.

An annular reinforcing plate 33 is embedded in the valve portion 31c, and a valve spring 34 for urging the valve portion 31c toward both valve seats 30 ₁ and 30 ₂ is contracted between this and the input rod 25. It

On the inner surface of the valve cylinder 8, one end of the first bifurcated port 20 is located outside the first valve seat 30 _{1 and} the second end is located inside the valve seat 30 ₁
One end of each bifurcated port 21 opens.

The inside of the second valve seat 30 ₂ communicates with the atmosphere introduction port 23 through the hollow portion of the valve body 31 and the holding cylinder 32.

Thus, the valve body 31, the valve spring 34, the first valve seat 30 ₁ and the second valve seat 30 ₂ constitute the control valve 22.

Between the input rod 25 and the holding cylinder 32, a return spring 35 for urging the input rod 25 toward its retracted limit is contracted.

The retreat limit of the input rod 25 is regulated by the stopper plate 36 screwed to the input rod 25 so as to be adjustable forward and backward to come into contact with the inner surface of the end wall 11a of the rear extension cylinder 11. Therefore, the stopper plate 36
When is turned, the screwing position of the stopper plate 36 and the input rod 25 is changed, so that the backward limit of the input rod 25 can be adjusted back and forth. After the adjustment, the stopper plate 36 is fixed in the same manner as the input rod.
It is performed by tightening a lock nut 37 screwed to 25. The stopper plate 36 is provided with a ventilation hole 38 so that the stopper plate 36 does not block the atmosphere introduction port 23.

An air filter 39 for filtering air taken into the valve cylinder 8 from the air introduction port 23 is attached to the valve cylinder 8 so as to surround the input rod 25. This air filter 39 includes an input rod 25 and a valve cylinder 8.
It has appropriate flexibility so as not to interfere with relative displacement with.

The partition wall 8a of the valve cylinder 8 is provided with a large cylinder hole 27 that opens at the center of the front surface thereof. The large cylinder hole 27 and the small cylinder hole 26 having a smaller diameter than that of the large cylinder hole 27 communicate with each other at the back of them. Have the depth to do. An elastic piston 40 made of rubber, the rear end surface of which faces the valve piston 28, is tightly fitted in the large cylinder hole 27, and an output piston 41 abutting on the front surface of the elastic piston 40 is loosely fitted in the large cylinder hole 27.
An output rod 43 connected to the piston 42 of the brake master cylinder M is press-fitted and coupled to 41. This output rod 43 is
By loosely fitting the output piston 41 into the large cylinder hole 27, the output piston 41 can be swung with respect to the valve cylinder 8. Thus, the valve piston 28,
The elastic piston 40 and the output piston 41 constitute a reaction force mechanism 44.

Between the output piston 41 and the output rod 43, a retainer 45 extending toward the cylinder shaft 14 side of the front booster piston 4 is clamped,
An inward flange 14a that abuts the rear surface of the retainer 45 in a separable manner is formed at the rear end of the cylindrical shaft 14. A return spring 46 is contracted between the retainer 45 and the front wall of the booster shell 1. Therefore, the return spring 46 applies a retracting force to the front booster piston 4 via the retainer 45, and also applies a retracting force to the rear booster piston 6 via the retainer 45, the reaction mechanism 44 and the valve cylinder 8.

The rearward limit of the rear booster piston 6 is restricted by a large number of protrusions 7a protruding on the rear surface of the rear diaphragm 7 contacting the rear wall of the booster shell 1, but the front diaphragm 5 remains on the partition plate 1c even when it is retracted. Do not touch.

Next, the operation of this embodiment will be described. First, in the rest state of the negative pressure booster B, as shown in FIG. 1, the input rod 25 is located at the backward limit, and the control valve 22 moves the valve portion 31c to the first and second valve seats 30 ₁ and 30 ₂ . After being seated, both the front and rear working chambers 2b, 3b are in a neutral state in which both the negative pressure chambers 2a, 3a and the atmosphere introduction port 23 are in a non-communication state. 3
The negative pressure of the negative pressure source supplied through the negative pressure introducing pipe 19 is stored in a, and the negative pressure appropriately diluted by the atmosphere is held in both working chambers 2b and 3b. Thus, a slight forward force is applied to the front and rear booster pistons 4 and 6 due to the difference in atmospheric pressure between the front negative pressure chamber 2a and the working chamber 2b, and the rear negative pressure chamber 3a and the working chamber 3b. The forward force and the elastic force of the return spring 46 balance each other, and the booster pistons 4 and 6 are stopped at a position slightly advanced from the backward limit.

Now step on the brake pedal 24 to brake the vehicle,
If it caused to advance the input rod 25 and the valve piston 28, initially, since the valve cylinder 8 does not move, the second valve seat 30 ₂ immediately away both working chambers 2b from the valve portion 31c, the 3b to the air inlet port 23 Communicate. As a result, the atmosphere flows from the air inlet 23 to the second valve seat 30 ₂ and the second
Since it is quickly introduced into both working chambers 2b and 3b through the bifurcated port 21 and makes the chambers 2b and 3b higher in pressure than the negative pressure chambers 2a and 3a, a large forward force based on the pressure difference between them is obtained to obtain both booster pistons 4 , 6 move forward with good response against the force of the return spring 46,
Piston of brake master cylinder M via output rod 43
Drive 42 forward. In this way, the brake master cylinder M is operated without delay when the brake pedal 24 is depressed,
You can brake the vehicle.

During such braking, the input rod 25 contacts the elastic piston 40 via the valve piston 28 as the input rod 25 moves forward, and the elastic piston 40 receives the operation reaction force of the rear booster piston 6 and the small cylinder hole 26. Valve piston 28
Since a part of the reaction force is applied to, the force is fed back to the brake pedal 24 side via the valve piston 28 and the input rod 25. With such a function of the reaction force mechanism 44, the operator can detect the output of the output rod 43, that is, the magnitude of the braking force.

In this case, since the reaction force mechanism 44 does not receive the operation reaction force of the booster piston 4 but only the braking reaction force of the rear booster piston 6, the small cylinder hole 26 into which the valve piston 28 and the elastic piston 40 are fitted and A large boosting ratio can be obtained without increasing the cross-sectional area ratio of the large cylinder hole 27, and therefore the load of the reaction force mechanism 44 can be reduced and its durability can be improved.

When the output of the output rod 43 exceeds the boost limit point due to an increase in the pedaling force on the brake pedal 24, that is, the input of the input rod 25,
Since the valve piston 28 whose tip is brought into contact with the elastic piston 40 also brings the flange 28a of the intermediate portion into contact with the step portion 29 of the valve cylinder 8, the entire input is the valve piston 28, the valve cylinder 8, the elastic piston 40 and the output. The force is transmitted to the output rod 43 via the piston 41, and eventually the sum of the forward force due to the atmospheric pressure difference between the booster pistons 4 and 6 and the forward force due to the input is output from the output rod 43.

By the way, when the input of the input rod 25 mechanically acts on the valve cylinder 8 via the valve piston 28, the input rod 25 swings with respect to the valve piston 28 according to the rotational position of the brake pedal 24. From the relationship, the input direction of the input rod 25 is
Since the valve cylinder 8 and the axis of the valve cylinder 8 are slightly inclined, a tilting moment acts on the valve cylinder 8 by this. However, in the present invention, as described above, the valve cylinder 8, the front booster piston 4
Since the three members of the cylinder shaft 14 and the output rod 43 can swing with respect to each other, the tilting moments are absorbed by the swinging action of these little by little, so that an unreasonable prying force is not generated in each part and the brake is applied. The master cylinder M can be operated smoothly.

Next, when the pedal force on the brake pedal 24 is released,
First, the input rod 25 moves the valve piston 28 by the elastic force of the return spring 35.
With this, the second valve seat 30 ₂ is seated on the valve portion 31c of the valve body 31 and the valve portion 31c is largely separated from the first valve portion 30 _1, so that both working chambers 2b and 3b are separated from each other into the negative pressure chamber 2a. , 3a communicates with the booster pistons 4 and 6 immediately, and the pressure difference between the booster pistons 4 and 6 disappears immediately. . The input rod 25 extends the stopper plate 36 into the extension cylinder 11
2, the rear booster piston 6 returns to the rearward limit in which the projection 7a of the rear diaphragm 7 is brought into contact with the rear wall of the booster shell 1, as shown in FIG. This time, the second valve seat 30 ₂ is seated on the valve seat 31c and the valve portion 31c is slightly separated from the second valve seat 30 ₂ so that the atmosphere is introduced again into both working chambers 2b and 3b. If the booster pistons 4 and 6 move slightly forward due to the generated atmospheric pressure difference, the booster pistons 4 and 6 move forward so as to eliminate the small gap between the _second valve seat 302 and the valve seat 31c, and bring the control valve 22 to the initial neutral state. In this way, the negative pressure diluted with the atmosphere is held in both working chambers 2b and 3b, and the negative pressure booster B is in the rest state shown in FIG.

C. Effects of the Invention As described above, according to the present invention, the cylinder shaft extending rearward from the booster piston is loosely inserted into the guide hole of the valve cylinder, and the guide shaft inner peripheral surface is formed on the outer peripheral surface of the cylinder shaft. By providing a pair of protrusions protruding so as to sandwich the annular seal member in contact with each other and sliding the seal member and the protrusions on the inner peripheral surface of the guide hole, the cylinder shaft can be swung with respect to the guide hole. In addition, the output piston of the reaction mechanism fixed to the rear end of the output rod is loosely fitted in the cylinder hole of the valve cylinder so that the output rod can be swung with respect to the valve cylinder. Even if a large tilting moment is applied to the cylinder, it can be absorbed by the swinging action of the valve cylinder, the front booster piston, and the output rod, and the generation of the prying force can be effectively prevented, so that the input rod can be effectively prevented. Input of the input is transmitted accurately to the output rod without loss. It is possible.

Further, in particular, since the seal member placed between the cylinder shaft and the guide hole is located at the swing fulcrum of the cylinder shaft with respect to the guide hole, the seal member is locally moved even when the cylinder shaft swings. There is no risk of receiving an excessive compressive load, and it is possible to accurately seal between the cylindrical shaft and the guide hole for a long period of time, and the durability of the seal member itself is also good.

[Brief description of drawings]

The drawings show an embodiment of the present invention. Fig. 1 is a vertical sectional side view of a tandem type negative pressure booster in a rest state, and Fig. 2 shows a state immediately before the booster finishes its operation and returns to its rest position. It is a partial longitudinal section side view shown. B ... Negative pressure booster 1 ... Booster shell, 1c ... Partition plate, 2,3 ... Front and rear shell chambers, 2a, 3a ... Front and rear negative pressure chambers, 2b, 3b ...
Front and rear working chambers, 4, 6 ... Front and rear booster pistons,
8 ... Valve cylinder, 14 ... Cylindrical shaft, 15 ... Guide hole, 16 ... Sealing member, 18 ... Projection, 22 ... Control valve, 25 ... Input rod, 27 ...
… Large cylinder hole as cylinder hole, 40 …… elastic piston, 41 …… output piston, 43 …… output rod, 44 …… reaction mechanism

Claims (1)

[Claims] 1. A booster shell (1) is provided with a partition plate (1c) for partitioning its interior into a front shell chamber (2) and a rear shell chamber (3), and a rear wall () of the booster shell (1). 1b)
A rear booster piston (6) that divides the rear shell chamber (3) into a front negative pressure chamber (3a) and a rear working chamber (3b) in a valve cylinder (8) that is slidably supported in the front and rear. The output rod (43) is connected to the output rod (43) through the reaction force mechanism (44), and the front shell chamber (2) is connected to the front negative pressure chamber (2a) and the rear. The front booster piston (4) which is divided into the side working chamber (2b) is connected, both negative pressure chambers (2a, 3a) are connected to the negative pressure source, and the valve cylinder (8) can be moved back and forth. Input rod (25)
Depending on the back and forth movement of this input rod (25), both working chambers (2b, 3
In a tandem type negative pressure booster in which a control valve (22) for switching communication between b) to the atmosphere and both negative pressure chambers (2a, 3a) is arranged, the tandem type negative pressure booster is provided so as to project from the rear surface of the front booster piston (4). Cylindrical shaft (1
4) is loosely inserted into a guide hole (15) opening at the front end surface of the valve cylinder (8), and the guide hole (1) is formed on the outer peripheral surface of the cylinder shaft (14).
5) A pair of ridges (18, 18) protruding so as to sandwich the annular seal member (16) in contact with the inner peripheral surface are provided, and the seal member (16) and the ridges (18, 18) The cylinder shaft (14) is swingably supported with respect to the guide hole (15) by sliding the guide shaft (15) on the inner peripheral surface of the guide hole (15), and the reaction force mechanism (44) includes the front end of the valve cylinder (8). An elastic piston (40) that is tightly fitted in a cylinder hole (27) that is open to the surface so that the input rod (25) can abut when it advances, and an output rod (43) that abuts on the front face of the elastic piston (40). And an output piston (41) fixed to the rear end of the cylinder. The output piston (41) has a cylinder hole (27) so that the output rod (43) can be swung with respect to the valve cylinder (8). Tandem type negative pressure booster characterized by being loosely fitted in.