JPH0417415Y2 - - Google Patents

Description

[Detailed explanation of the invention] A. Purpose of the invention (1) Industrial application field The invention consists of a negative pressure chamber connected to a negative pressure source by a booster piston housed inside the booster shell so as to be able to move back and forth, and a negative pressure chamber connected to a negative pressure source. The rear side of the negative pressure chamber is divided into an adjacent working chamber, and a valve cylinder containing a control valve for switching and controlling communication between the working chamber and the negative pressure chamber or the atmosphere is connected to the rear of the piston boss. The present invention relates to a negative pressure booster in which a booster piston is coupled to a piston boss, and a return coil spring for urging the booster piston in a backward direction is compressed between the booster piston and the front wall of a negative pressure chamber.

(2) Conventional technology Such a negative pressure booster is known as, for example, the
This method is already known as disclosed in the publication No.

(3) Problems to be solved by the invention In conventional negative pressure boosters, the rear end of the return coil spring is supported directly on the front surface of the piston boss of the booster piston, so it is possible to eliminate biased contact between the spring and the piston boss. For this reason, the rear end of the spring is not cut completely, but the rear end face is ground smooth, but such machining is troublesome and becomes an obstacle to cost reduction.

The present invention was developed in view of the above circumstances, and it is possible to eliminate the uneven contact of the return coil spring without special grinding the rear end surface of the return coil spring, and also to suppress the vibration of the spring and prevent noise. The purpose is to provide a pressure booster.

B. Structure of the invention (1) Means for solving the problem In order to achieve the above object, the present invention creates a negative pressure chamber connected to a negative pressure source by a booster piston housed inside the booster shell so that it can freely reciprocate back and forth. The negative pressure chamber is divided into an adjacent working chamber on the rear side, and a valve cylinder housing a control valve for switching and controlling communication between the working chamber and the negative pressure chamber or the atmosphere is connected to the rear of the piston boss. , connect the inner peripheral part of the booster piston to the front surface of the piston boss with a screw member,
A negative pressure booster is provided with a return coil spring compressed between the booster piston and the front wall of the negative pressure chamber for biasing the booster piston in the backward direction, and the seat plate for receiving the screw member is installed inside the booster piston. The seat plate has an annular shape which is superimposed on the front surface of the circumferential part and is fastened to the booster piston by the screw member, and has a bent part in the middle and whose tip part elastically supports the rear end part of the return coil spring. The present invention is characterized in that a plurality of arranged leg pieces are integrally arranged in series, and a supporting portion of each leg piece for the return coil spring is located in front of the screw member.

(2) Effect According to the above configuration, the rear end of the return coil spring is left uncut, and even if the rear end surface is not specially ground, the slope of the rear end surface is equal to the slope of the plurality of legs on the seat plate. Since this is absorbed by the elastic deformation of the bent portion, all the leg pieces work together to reliably support the rear end of the return coil spring without bias.

Further, when the return coil spring vibrates, the vibration is suppressed by each leg piece having a different natural frequency from that of the return coil spring.

Further, since the supporting portion of each leg piece for the return coil spring is located in front of the screw member, mutual interference between the rear end surface of the return coil spring and the screw member is avoided.

(3) Embodiment An embodiment of the present invention will be described below with reference to the drawings.

First, in FIG. 1, on the front of the booster shell 1 of the tandem negative pressure booster B, the booster B
A brake master cylinder M, which is operated by the brake master cylinder M, is attached.

The booster shell 1 includes a pair of front and rear shell halves 1a, 1b whose opposite ends are connected to each other, and is sandwiched between the two shell halves 1a, 1b so that the inside of the booster shell 1 is divided into a front shell chamber 2 and a rear shell chamber. 3, and a partition wall plate 1c that partitions the rear shell half body 1b into
is supported by a vehicle body (not shown).

The front shell chamber 2 includes a front booster piston 4 made of a steel plate that is housed therein so as to be able to reciprocate back and forth, and a front shell half body 1 that is superimposed and bonded to the rear surface.
A and a rubber front diaphragm 5 sandwiched between the partition wall plate 1c and the front negative pressure chamber 2a on the front side and a front working chamber 2b on the rear side. Further, the rear shell chamber 3 has a rear booster piston 6 made of a steel plate accommodated therein so as to be able to reciprocate back and forth, and is bonded to the rear face thereof, and is fixed together with the partition wall plate 1c between the two shell halves 1a and 1b. A rear diaphragm 7 made of rubber divides the chamber into a rear negative pressure chamber 3a on the front side and a rear working chamber 3b on the rear side.

The front and rear booster pistons 4 and 6 are each formed into an annular shape from a steel plate, and these are connected to the partition wall plate 1c.
It is connected to both ends of a piston boss 10 made of synthetic resin which is slidably supported via a bush 8 and a seal member 9 in the following manner.

That is, the depth of the piston boss 10 is
A circular recess 11 reaching approximately half the length of 0 is formed on the front end surface, and a flange 12 is protruded from the rear end of the outer peripheral surface at a location slightly forward.
The circular recess 11 includes a front booster piston 4.
A connecting cylinder 1 with an end wall plate 13a connected to the inner peripheral end of the
3 are fitted together, and a presser plate 14 that cooperates with the flange 12 to clamp the rear booster piston 6 is superimposed on the rear end surface of the piston boss 10. The presser plate 14, the piston boss 10, and the end wall plate 13a are connected to a plurality of (three in the illustration) through bolts 15 surrounding the axis of the piston boss 10,
They are fixed to each other by a nut 16 screwed into them.

At that time, between the front booster piston 4 and the front end surface of the piston boss 10, there is provided an inner peripheral bead 5a of the front diaphragm 5, and a metal annular retainer 17 that covers the outer peripheral surface and rear surface of the inner peripheral bead 5a. is inserted between the flange 12 and the holding plate 14, and the inner peripheral bead 7a of the rear diaphragm 7, which wraps around the inner peripheral end of the rear booster piston 6, is inserted between the flange 12 and the holding plate 14.
Therefore, the front and rear booster pistons 4, 6 and the piston boss 10 are connected to each other, and at the same time, the inner bead 5 of each diaphragm 5, 7 is connected to each other.
a, 7a are fixed to the corresponding booster pistons 4, 6.

Further, a sealing member 19 is attached to the bolt hole 18 provided in the piston boss 10 for insertion of the through bolt 15, so that the bolt hole 18
communication between the front negative pressure chamber 2a and the rear working chamber 3b is blocked. Further, a sealing member 20 surrounding the plurality of through bolts 15 is interposed between the end wall plate 13a and the piston boss 10, so that the gap between the contact surfaces of the end wall plate 13a and the piston boss 10 First and second ports 30 and 31 described below
communication between them is blocked.

Each through bolt 15 is arranged with its square head 15a facing the rear working chamber 3b side, and its square head 15
A recess 21 (see FIG. 2) of the same shape is formed in the presser plate 14, into which the recess 21 (see FIG. 2) is fitted non-rotatably. Therefore, when the nut 16 is passed through and screwed onto the bolt 15 on the front negative pressure chamber 2a side, the bolt 15 is prevented from rotating, so that the nut 16 can be tightened reliably.

The through bolt 15 and nut 16 constitute the threaded member of the present invention, and the steel plate seat plate 22 is bonded to the end wall plate 13a of the connecting cylinder 13 in an overlapping manner. This seat plate 22 is provided with a plurality of leg pieces 39 (see FIGS. 1 and 3) that stand up higher than the height of the protrusion of the bolt 15 between the plurality of nuts 16, and the seat plate 22 and the front A return coil spring 23 that biases the piston boss 10 in the backward direction is compressed between the shell half 1a and the piston boss 10. In this way, the return coil spring 23 is received in the recess 11 on the front surface of the piston boss 10 together with the connecting cylinder 13.

The plurality of leg pieces 39 each have a bent part 39a in the middle to have appropriate elasticity, and each of the leg pieces 39 has a support part 39b on the tip side that directly receives the rear end surface of the return coil spring 23. Each support part 39b
The tip is slightly bent forward so as to hold the rear end of the return coil spring 23. The end of the return coil spring 23 on the rear end side is left uncut, and the rear end surface is not particularly ground and is supported by the support portion 39a at the tip of each leg piece 39 as it is.

The backward limit of both booster pistons 4 and 6 is regulated by a large number of projections 24 raised on the rear surface of rear diaphragm 6 coming into contact with the rear wall of booster shell 1.

The front negative pressure chamber 2a is connected to a negative pressure source (not shown, for example, inside an intake manifold of an internal combustion engine) via a negative pressure introduction pipe 29. Further, both the front and rear negative pressure chambers 2a, 3a communicate with the inside of the valve cylinder 25 via a bifurcated first port 30 formed in the piston boss 10, and both the front and rear working chambers 2b, 3b are connected in the same way. A pair of second ports 3 formed in the piston boss 10
It communicates with the inside of the valve cylinder 25 via 1 and 31. The second ports 31 and 31 are connected to the first port 30 and the end wall 26 of the rear extension tube 26 by the control valve 32.
Communication is alternately switched to the atmospheric air inlet 33 which opens to a.

Inside the valve cylinder 25, an input rod 35 connected to the brake pedal 34 and the control valve 32 controlled by the input rod 35 are provided as follows. That is, a valve piston 38 is slid into the front part of the valve cylinder 25, and the front end of an input rod 35 passing through the air inlet 33 is swingably connected to the valve piston 38. Further, an annular first valve seat 40 ₁ is protruded from the inner peripheral surface of the valve cylinder 25 , and an annular second valve seat 40 surrounded by the annular first valve seat 40 1 is provided.
₂ is formed on the rear end surface of the valve piston 38, and a valve body 41 that cooperates with these valve seats 40 ₁ and 40 ₂ is attached to the valve cylinder 25.
located within. The valve body 41 is made of rubber and has a cylindrical shape with both front and rear ends open, and the rear end, that is, the base end 41a, is held by a holding cylinder 42 fitted to the inner peripheral surface of the valve cylinder 25. It is maintained in close contact with the inner peripheral surface of the cylinder 25. The valve body 41 includes a thin flexible portion 41b bent radially inward from the base end 41a, and a thick valve portion 41c continuous to the front end of the flexible portion 41b. 41c is arranged opposite to the first and second valve seats 40 ₁ and 40 ₂ .

The valve part 41c can be moved back and forth by deforming the flexible part 41b, and is seated on the first and second valve seats 40 ₁ and 40 ₂ when moving forward, and is received at the front end of the holding cylinder 42 when retreating. It can be stopped.

An annular reinforcing plate 43 is embedded in the valve portion 41c,
A valve spring 44 is compressed between this and the input rod 35 and urges the valve portion 41c toward both valve seats 40 ₁ and 40 ₂ .

On the inner surface of the valve cylinder 25, one end of the first port 30 is located outside the first valve seat 40 ₁ , and one end of the first port 30 is located outside the first valve seat 40 ₁ .
One end of each of the second ports 31 opens inside the second port 31 .

Further, the inside of the second valve seat 40 ₂ communicates with the atmosphere inlet 33 through the hollow portion of the valve body 41 and the holding cylinder 42 .

Thus, the valve body 41, the valve spring 44, and the first valve seat 40
_{The first} and second valve seats 40 ₂ constitute the control valve 32 .

Between the input rod 35 and the holding cylinder 42, the input rod 35
A return spring 45 is provided that urges the rear end toward its retraction limit.

The retraction limit of the input rod 35 is determined by a stopper plate 46 that is screwed to the input rod 35 so as to be able to move forward and backward.
It is regulated by contacting the inner surface of the end wall 26a. Therefore, by rotating the stopper plate 46, the screwing position between the stopper plate 46 and the input rod 35 changes, so that the retraction limit of the input rod 35 can be adjusted back and forth. Fixing of the stopper plate 46 after this adjustment is as follows.
This is done by tightening a lock nut 47 which is similarly screwed onto the input rod 35. The stopper plate 46 includes
A ventilation hole 48 is provided to prevent this from blocking the air inlet 33.

The valve cylinder 25 is provided with an air filter 4 for filtering air taken into the valve cylinder 25 from the atmosphere inlet 33.
9 is attached to surround the input rod 35. This air filter 49 has appropriate flexibility so as not to impede relative displacement between the input rod 35 and the valve cylinder 25.

The piston boss 10 has a large cylinder hole 37 that opens at the center of its front surface, and a large cylinder hole 37 that opens at the center of the front surface.
and a small cylinder hole 3 whose both ends are open inside the valve cylinder 25.
6 is provided. And in the small cylinder 36,
Integral with the valve piston 38 or valve piston 38
A reaction piston 52 that comes into contact with the large cylinder hole 37 is slidably fitted with an elastic piston 50 that faces the reaction piston 52 and an output piston 51 that is superimposed on the front surface of the elastic piston 50.
In order to prevent the output piston 51 from being pulled out of the large cylinder hole 37, the inner peripheral edge of the end wall plate 13a is extended to the opening of the large cylinder hole 37.

An output rod 53 is provided protruding from the front surface of the output piston 51, and this output rod 53 is connected to the piston 55 of the brake master cylinder M.

Next, the operation of this embodiment will be explained. First, when the negative pressure booster B is at rest, as shown in Fig. 1,
The input rod 35 is located at the backward limit, and the control valve 32 has the valve portion 41c seated on the first and second valve seats 40 ₁ and 40 ₂ so that both the front and rear working chambers 2b and 3b are connected to both the negative pressure chambers 2.
The control valve 32 is in a neutral state where it is disconnected from both the negative pressure chambers 2a and 3a and the atmospheric air inlet 33. Negative pressure is stored, and the negative pressure appropriately diluted with the atmosphere is maintained in both working chambers 2b and 3b. In this way, a slight forward force is applied to the front and rear booster pistons 4 and 6 due to the pressure difference generated between the negative pressure chamber 2a and the working chamber 2b at the front, and between the negative pressure chamber 3a and the working chamber 3b at the rear. ,
These forward forces and the elastic force of the return coil spring 23 are balanced, and both the booster pistons 4 and 6 are stopped when they have advanced slightly from the retraction limit.

Now, when the brake pedal 34 is depressed to brake the vehicle and the input rod 35 and the valve piston 38 are moved forward, since both the booster pistons 4 and 6 are initially immovable, the second valve seat ₄₀₂ is moved to the valve portion 41c. Immediately move away from the air intake port 33 and connect both working chambers 2b, 3b to the atmosphere inlet 33.
communicate with. As a result, the atmosphere is
is quickly introduced into both working chambers 2b and 3b through the second valve seat 40 ₂ and the second port 31, and the chamber 2
Since the pressure in the negative pressure chambers 2a and 3b is higher than that in the negative pressure chambers 2a and 3a, a large forward force is obtained based on the pressure difference between them, and both the booster pistons 4 and 6 return to the coil spring 23.
The piston 55 of the brake master cylinder M is driven forward through the output rod 53. In this way, the brake master cylinder M can be operated without delay when the brake pedal 34 is depressed, and the vehicle can be braked.

During such braking, the valve piston 38 also advances together with the input rod 35 and comes into contact with the elastic piston 50 via the reaction piston 52.
0 bulges and deforms toward the small cylinder hole 36 side in response to the actuation reaction force of both booster pistons 4 and 6, and a part of the reaction force acts on the reaction force piston 52, so that force is applied to the valve piston 38 and Feedback is provided to the brake pedal 34 via the input rod 35. Due to such a reaction force, the driver can sense the output of the output rod 53, that is, the magnitude of the braking force.

When the output of the output rod 53 exceeds the boosting limit point due to an increase in the pedal force on the brake pedal 34, that is, the input to the input rod 35, the front surface of the valve piston 38 comes into contact with the piston boss 10, so that the entire input is applied to the valve piston. 38, the output rod 53 via the piston boss 10, the elastic piston 50 and the output piston 51
As a result, the sum of the forward force due to the pressure difference between the booster pistons 4 and 6 and the forward force due to the input is output from the output rod 53.

Next, when the pedal force on the brake pedal 34 is released, the input rod 35 moves back together with the valve piston 38 due to the elastic force of the return spring 45, and the second valve seat 4
0 ₂ is seated on the valve portion 41c of the valve body 41, and the valve portion 41c is separated from the first valve portion 40 ₁ by a large distance. The pressure difference between the front and rear of each booster piston 4, 6 is immediately eliminated by communicating with the negative pressure chambers 2a, 3a, and therefore both booster pistons 4, 6 retreat with the elastic force of the return coil spring 23, and the brake master The operation of cylinder M is released. Then, when the input rod 35 returns to the retraction limit where the stopper plate 46 comes into contact with the partition wall 26a of the extension tube 26, the rear booster piston 6 temporarily pushes the protrusion 24 of the rear diaphragm 7 into the booster shell, as shown in FIG. 1 returns to the retraction limit where it contacts the rear wall of 1, and this time, the first valve seat 40 ₁ is seated on the valve seat 41c and the valve part 41c is slightly separated from the second valve seat 40 ₂ , so that the second port 31 Atmospheric air is again introduced into both the working chambers 2b, 3b through the valve, but due to the resulting pressure difference, if both the booster pistons 4, 6 move forward a little, the small gap between the second valve seat ₄₀₂ and the valve part 41c disappears. The control valve 32 is brought to its initial neutral state. In this way both working chambers 2b, 3
A negative pressure diluted with the atmosphere is maintained at point b, and the negative pressure booster B enters the rest state as shown in FIG.

In such a tandem type negative pressure booster B, the piston boss 10, the front booster piston 4
A plurality of through bolts 15 arranged around the axis of the piston boss 10 connect the end wall plate 13a of the connecting cylinder 13 connected to the piston boss 10, and the presser plate 14 that cooperates with the piston boss 10 to clamp the rear booster piston 6.
and a nut 16 screwed together, and the inner peripheral bead 5 of the front diaphragm 5 is connected between the front booster piston 4 and the piston boss 10.
a, also the rear booster piston 6 and the holding plate 1
Since the inner peripheral beads 7a of the rear diaphragm 7 are inserted between the piston bosses 10 and 4, the front and rear pistons 4 and 6 and the front and rear diaphragms 5 and 7 can be connected to the piston boss 10 without dividing it. Moreover, since the end wall plate 13a and the holding plate 14 of the connecting cylinder 13 are restrained from rotating by the plurality of through bolts 15, they do not rotate even when the nut 16 is tightened, and as a result, the front and rear diaphragms 5 ，
7 can be prevented from twisting.

Further, a bolt 15 is attached to the front end surface of the piston boss 10.
and a bolt 1 to a seat plate 22 fixed with a nut 16.
A plurality of leg pieces 39 are formed in an annular arrangement that stand higher than the height of the protrusion 5 and have a bent part 39a in the middle, and these leg pieces 39 support the rear end of the return coil spring 23. The rear end of the return coil spring 23 is left uncut, and even if the rear end surface is not specially ground, the slope of the rear end surface can be adjusted to the intermediate bent portion 39 of the plurality of leg pieces 39 on the seat plate 22.
This is absorbed by the appropriate elastic deformation of a, so that the seat plate 22 can stably support the return coil spring 23 and apply the spring force accurately to the piston boss 10 as an axial load. Furthermore, since the leg piece 39 has a natural frequency different from that of the return coil spring 23, when the return coil spring 23 vibrates, it can effectively suppress the vibration and prevent the generation of noise.

C. Effects of the invention As described above, according to the invention, the seat plate that receives the screw member that connects the booster piston and the piston boss is superimposed on the front surface of the inner peripheral part of the booster piston, and the screw member is connected to the booster piston. The seat plate has a plurality of legs connected in an annular arrangement that each have a bent part in the middle and elastically support the rear end of the return coil spring at the tip. The rear end of the coil spring is left uncut, and the rear end surface does not have to be specially ground.
The inclination of the rear end surface can be absorbed by moderate elastic deformation of the intermediate bent portions of the plurality of legs in the seat plate, and the seat plate can be stably supported on the rear end of the return coil spring. This allows the spring force to be applied accurately to the boss of the booster piston. Moreover, the leg piece is
It also has a vibration suppressing function for the return coil spring, and can contribute to noise prevention. Furthermore, by integrating the plurality of leg pieces into the seat plate for receiving the screw member, the seat plate itself can also be used as a spring receiving means for the return coil spring, which simplifies the structure. This can contribute to cost reduction and improved assembly efficiency.

Further, since the support for the return coil spring of each of the leg pieces is located on the front side of the screw member, it is possible to avoid mutual interference between the rear end surface of the return coil spring and the screw member, and therefore, each of the leg pieces The elastic support function for the return coil spring can always be properly exerted without being hindered by the screw member in any way.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a vertical sectional side view of a tandem negative pressure booster in a rest state, and FIGS. 2 and 3 are sectional views taken along lines - and - in FIG. 1. , and FIG. 4 is a partial longitudinal sectional side view showing the negative pressure booster in a state immediately before returning to the rest state after completing its operation. B...Negative pressure booster, 1...Booster shell,
2a... Front negative pressure chamber as negative pressure chamber, 2b... Front working chamber as working chamber, 4... Front booster piston as booster piston, 10... Piston boss, 15, 16... Screw Through bolt and nut as members, 22...Seat plate, 23...Return coil spring, 25...Valve cylinder, 32...Control valve, 33
...Atmosphere inlet, 35...Input rod, 39...Leg piece, 39a...Bending part, 39b...Supporting part, 53
...output rod.

Claims (1)

[Scope of utility model registration request] The inside of the booster shell 1 is divided into a negative pressure chamber 2a connected to a negative pressure source and a working chamber 2b adjacent to the rear side of the negative pressure chamber 2a by a booster piston housed therein so as to be able to reciprocate back and forth. A valve cylinder 25 housing a control valve 32 for controlling communication between the negative pressure chamber 2b and the negative pressure chamber 2a or the atmosphere is connected to the rear of the piston boss 10, and the inner peripheral part of the booster piston 4 is attached to the front surface of the piston boss 10. Screw members 15, 16
The booster piston 4 and the negative pressure chamber 2a are connected by
This is a negative pressure booster in which a return coil spring 23 for urging the booster piston 4 in the backward direction is compressed between the front wall of the booster piston 4 and the seat plate 22 that receives the screw members 15 and 16. The seat plate 2 is overlapped with the front surface of the inner circumferential part and is fastened to the booster piston 4 by the screw members 15 and 16.
2, a plurality of leg pieces 39 in an annular arrangement each having a bent part 39a in the middle and whose distal end elastically supports the rear end of the return coil spring 23 are integrally arranged, and each of the leg pieces 39 return coil spring 23
The support portion 39b for the screw members 15, 16
A negative pressure booster characterized by being located further forward than the