JPH0495559A - Tandem type vacuum booster - Google Patents

Abstract

PURPOSE:To shorten a span of assembling time so sharply by using a sleeve being fitted in a piston boss and a stopper member being attached to this piston boss at a time when each inner circumferential end of both front and rear booster pistons and each inner circmferential bead of both front and rear diaphragms are all clamped to the piston boss. CONSTITUTION:When both front and rear booster pistons 4, 5 and also both front and rear diaphragms 5, 6 are all attached to a piston boss 10, a sleeve 12, being supported by a partition plate 1c partitioning the inside of a booster shell 1 into a front shell chamber 2 and a rear shell chamber 3 free of sliding motion, is fitted in an outer circumference of the piston boss 10, and an inner circumferential end of the front booster piston 4 and an inner circumferential bead 5a of the front diaphragm 5 are pressed in between by a front end of the sleeve 12 and a flange 10a installed in the piston boss 10, thus they are clamped to a front part of the piston boss 10. In addition, an inner circumferential end of a rear booster piston 6 and an inner circumferential bead 7a of a rear diaphragm 7 are pressed in between by a stopper member 13 attached to the piston boss 10 and a rear end of the sleeve 12, thus they are clamped to a rear part of the piston boss 10 as well.

Description

Detailed Description of the Invention A1 Object of the Invention (1) Industrial Application Field The present invention provides a booster shell with a partition plate fixed thereto that partitions the inside of the booster shell into a front shell chamber and a rear shell chamber. A front booster piston that divides the shell chamber into a front negative pressure chamber on the front side and a front working chamber on the rear side, and a front diaphragm superimposed on the rear surface, A rear booster piston partitioned into a rear working chamber on the side and a rear diaphragm superimposed on the rear surface are connected via a piston boss that passes through the partition plate and is connected to the output rod, and the rear end of this piston boss In the valve cylinder, which is connected to the cylinder and is slidably supported on the rear wall of the booster shell, there is an input rod that can move back and forth, and according to the back and forth movement of this input rod, both working chambers are connected to the atmosphere and both negative pressure chambers are connected to the valve cylinder. This invention relates to a tandem negative pressure booster equipped with a control valve that switches communication between the two.

(2) Prior Art Such a tandem negative pressure booster has already been proposed by the present applicant and is known, for example, from Japanese Patent Application Laid-Open No. 1-122766.

The tandem type negative pressure booster is a means for connecting the front and rear booster pistons and the front and rear diaphragms to the piston boss, and the connection is connected to the piston boss and the front booster piston and superimposed on the front end of the piston boss. Three members, the bulkhead plate of the cylinder and the presser plate superimposed on the rear end of the piston boss, are connected with multiple through bolts, so that the front booster piston is connected between the bulkhead plate and the front end of the piston boss. and the front diaphragm, and the rear booster piston and the rear diaphragm are fixed between the presser plate and the rear end of the piston boss.

(3) Problems to be solved by the invention However, the above conventional tandem negative pressure booster has the following problems:
Since it is necessary to pass a plurality of through-bolts through the piston boss, partition plate, and presser plate and tighten them, there is a disadvantage that not only the number of parts increases, but also a lot of effort and time is required for the assembly work.

The present invention has been made in view of the above, and it is an object of the present invention to provide the tandem type negative pressure booster, which allows easy connection of the front and rear booster pistons and the front and rear diaphragms to the piston boss. purpose.

B1 Configuration of the Invention (1) Means for Solving Problems In order to achieve the above object, the tandem type negative pressure booster of the present invention has a sleeve slidably supported on a partition wall plate attached to the outer periphery of the piston boss. The front end of the sleeve and the flange provided on the piston boss pinch the inner peripheral end of the front booster piston and the inner peripheral bead of the front diaphragm to fix it to the front part of the piston boss. The invention is characterized in that the inner peripheral end of the rear booster piston and the inner peripheral bead of the rear diaphragm are fixed to the rear part of the piston boss by pressing the inner peripheral end of the rear booster piston and the inner peripheral bead of the rear diaphragm between the stopper member attached to the rear end of the sleeve and the rear end of the sleeve.

(2) Effect According to the above configuration, first, by fitting the sleeve to the outer circumference of the piston boss, the inner circumferential end of the front booster piston and the front The inner peripheral bead of the diaphragm is clamped and fixed. Next, by attaching a stopper member to the piston boss, the inner peripheral end of the rear booster piston and the inner peripheral bead of the rear diaphragm are clamped and fixed between the stopper member and the rear end of the sleeve, and at the same time, the inner peripheral bead of the rear diaphragm is fixed to the piston boss. The fitted sleeve is prevented from falling off.

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

In FIG. 1, a brake mask cylinder M operated by the booster B is attached to the front surface of a booster shell 1 of a tandem negative pressure booster B. As shown in FIG.

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

The front shell chamber 2 includes a front booster piston 4 accommodated therein so as to be able to reciprocate back and forth, and a front booster piston 4 which is superimposed and bonded to the rear surface and sandwiched between the front shell half 1a and the partition plate 10. Through the diaphragm 5, the front negative pressure chamber 2a on the front side
and a rear front working chamber 2b. The rear shell chamber 3 also includes a rear booster piston 6 housed therein so as to be able to reciprocate back and forth, and a rear diaphragm 7 which is superimposed on the rear surface and fixed between the shell halves 1a and lb together with the partition wall plate 1c. Accordingly, it is divided into a rear negative pressure chamber 3a on the front side and a rear working chamber 3b on the rear side.

Front and rear booster pistons 4.6, which are formed into annular shapes from steel plates, are connected to the front and rear ends of a piston boss 10 made of synthetic resin, respectively, and the piston boss 10 is positioned between both booster pistons 4, 6. A sleeve 12 that fits around the outer periphery of the partition plate 1c is slidably supported via a bush 8 and a seal member 9.

That is, the piston boss 10 has a circular recess 11 whose depth reaches approximately half the length of the boss 10 on the front end surface thereof, and a flange 10a is provided protruding from the periphery of the opening of the circular recess 11. The inner circumferential end of the front booster piston 4 and the inner circumferential bead 5a of the front diaphragm 5 are engaged with the flange 10a in an overlapping state, and the outer circumference of the piston boss 10 is attached to the rear surface of the inner circumferential bead 5a from the rear to the front. The front end of the cylindrical sleeve 12, which is inserted toward the front end, comes into contact with the front end of the cylindrical sleeve 12. Thereby, the front booster piston 4 and the front diaphragm 5 are compressed by the flange 10a and the sleeve 12, and are firmly fixed to the front part of the piston boss 10. A stepped portion 10 formed on the piston boss 10 so as to be located inside the rear end of the sleeve 12
b, the inner peripheral end of the rear booster piston 6 and the inner peripheral bead 7a of the rear diaphragm 7 are engaged in a superimposed state, and the rear surface of the inner peripheral bead 7a is locked by a set ring 13 as a stopper member. . That is, the set ring 13
The stepped portion 10 has a large number of claws 13a protruding from its inner periphery.
The set ring 13 is attached to the piston boss 10 by engaging with the block groove 10C continuous to the rear part of the ring b.
As a result, the rear booster piston 6 and the rear diaphragm 7 are firmly fixed to the rear part of the piston boss 10, and the axial movement of the sleeve 12 that fits into the piston boss 10 is restricted.

A first boat 14 is formed in the piston boss 10 to connect the front and rear working chambers 2b, 3b to the atmosphere via a control valve 32, which will be described later. As is clear from FIG. 2 and FIG. 3, the first boat 14 is the piston boss 1.
A passage 14a that radially penetrates the rear end of the piston boss 0 to communicate the rear working chamber 3b and the control valve 32, a passage 14b having an arcuate cross section formed in the axial direction inside the piston boss 0, and a front end of the passage 14b. Passage 1 rising radially outward from
4C1, a groove formed on the inner surface of the sleeve 12, and the outer periphery of the piston boss 10, and a passage 14d communicating with the front working chamber 2b. Further, a second port 15 that communicates the front and rear working chambers 2b, 3b with the front and rear negative pressure chambers 2a, 2b via the first boat 14 and the control valve 32 is located inside the piston boss 10. A passageway 15a having an arcuate cross section that connects the control valve 32 and the front negative pressure chamber 2a through the passageway 15a in the axial direction; a passageway 15b extending radially outward from the passageway 15a; The passage 15c is defined between the groove and the front surface of the rear booster piston 6 and communicates the passage 15b with the rear negative pressure chamber 3a. And the piston,
A recess 10 is formed on the outer periphery of the piston boss 10 in order to align the passages 14c and 15b formed on the boss 10 side with the passages 14d and 15c formed on the sleeve 12 side.
d and a convex portion 12a formed on the inner periphery of the sleeve 12 engage with each other (see FIG. 3). The O-ring 1 is attached to the seal groove 10e formed on the outer periphery of the piston boss 10.
6 seals the contact surface between the outer periphery of the piston boss 10 and the inner periphery of the sleeve 12.

Thus, the first boat 14 communicating with the front working chamber 2b is
Communication between the front negative pressure chamber 2a and the rear negative pressure chamber 3a is blocked by the inner peripheral bead 5a of the front diaphragm 5 and the O-ring 16, and both negative pressure chambers 2a are prevented from communicating with each other.

The second boat 15 communicating with the rear working chamber 3b and the front working chamber 2b is blocked by the inner peripheral bead 7a of the rear diaphragm 7 and the O-ring 16.

A return spring 23 is compressed between the circular recess 11 formed at the front end of the piston boss 10 and the front shell half 1a, and the spring force of the return spring 23 causes the piston boss 10, that is, both booster pistons 4 and 6 is always urged in the backward direction. The backward limit of both booster pistons 4.6 is regulated by a large number of projections 24 raised on the rear surface of the rear diaphragm 6 coming into contact with the rear wall of the 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, and is connected to a negative pressure source (for example, inside an intake manifold of an internal combustion engine) via a second boat 15 formed in the piston boss 10. It communicates with the rear negative pressure chamber 3a. Also, front and rear working chambers 2b.

3b are communicated with each other via a first boat 14 formed in the piston boss 10, and are connected to the front and rear negative pressure chambers 2a, 3a by a control valve 32, and a rear extension cylinder 26 connected to the rear end of the booster shell 1. Air inlet 3 opening in end wall 26a
Communication is switched alternately between 3 and 3.

In the valve cylinder 25 connected to the rear of the piston boss 10, 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 39 is protruded from the inner peripheral surface of the valve cylinder 25, and an annular second valve seat 40 surrounded by this is formed on the rear end surface of the valve piston 38. A valve body 41 cooperating with 40 is arranged in the valve barrel 25 . 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 circumferential 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 41b1 bent radially inward from the base end 841a and a thick valve portion 41c continuous to the front end of the flexible portion 41b. are arranged opposite the first and second valve seats 39,40. Therefore, the valve portion 41c is made of flexible B41.
It is possible to move back and forth by deforming b, and when moving forward, it is seated on the first and second valve seats 39, 40, and when moving backward, it is received at the front end of the holding cylinder 42.

An annular reinforcing plate 43 is embedded in the valve 841c, and a valve spring 44 that biases the valve portion 41c toward both valve seats 39 and 40 is compressed between this and the input rod 35. On the inner surface of the valve cylinder 25, one end of the second port 15 opens on the outside of the first valve seat 39, and one end of the first boat 14 opens on the inside of the valve seat 39. Further, the inside of the second valve seat 4o 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 3
9 and the second valve seat 40 constitute the control valve 32.

A return spring 45 is compressed between the input rod 35 and the holding cylinder 42 and urges the input rod 35 toward its retraction limit. The backward limit of the input rod 35 is regulated by a stopper plate 46, which is screwed to the input rod 35 so as to be adjustable in forward and backward movement, abutting against the inner surface of the end wall 26a of the rear extension tube 26 via washers +, 48. Therefore, if the stopper plate 46 is rotated, the stopper plate 4
6 and the input rod 35 will change, so the input rod 35
The retraction limit can be adjusted back and forth. After this adjustment, the stopper plate 46 is fixed by tightening a lock nut 47 which is also threaded onto the input rod 35. The washer 48 is provided with a vent hole 48a so that the washer 48 does not block the air inlet port 33.

An air filter 49 is attached to the input rod 35 of the valve cylinder 25 for filtering the air taken into the valve cylinder 25 from the atmosphere inlet 33.
It is attached around the 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 is provided with a large cylinder hole 37 that opens at the center of its front surface, and a small cylinder hole 36 that opens at both ends into the large cylinder hole 37 and the valve cylinder 25 . In the small cylinder hole 36, a reaction force piston 52 that is integral with or in contact with the valve piston 38 is slidably fitted, and in the large cylinder hole 37, an elastic piston 50 that opposes the reaction force piston 52 and this elastic An overlapping output piston 51 is slid onto the front surface of the piston 5o.

In order to prevent the output piston 51 from being pulled out from the large cylinder hole 37, a set ring 54 is attached to the opening of the large cylinder hole 37.

An output rod 53 is protruded from the front surface of the output piston 51, and the output rod 53 is connected to the piston 55 of the brake mask cylinder M.

Next, the operation of this embodiment will be explained. First, negative pressure booster B
In the rest state, as shown in FIG. 1, the input rod 35 is located at the retraction limit, and the control valve 32 is moved toward the front and rear sides with the valve portion 41c seated on the first and second valve seats 39,40. working chamber 2b,
3b is the surface pressure chamber 2a.

3a and the atmosphere inlet 33, and by such a control valve 32, the surface corrosion pressure chamber 2a
, 3a store negative pressure from a negative pressure source supplied through the negative pressure introduction pipe 29, and both working chambers 2b, 3b maintain negative pressure appropriately diluted with the atmosphere. Thus, the front negative pressure chamber 2a and the working chamber 2b are provided in the front and rear booster pistons 4.6.

A slight forward force is applied due to the pressure difference between the rear negative pressure chamber 3a and the working chamber 3b, but these forward forces and the elastic force of the return spring 23 are balanced, and both booster pistons 4. 6 has stopped after slightly advancing from the reverse limit.

Now, step on the brake pedal 34 to brake the vehicle,
If the input rod 35 and the valve piston 38 are moved forward, initially,
Both booster pistons4. 61 is not 1b, the second valve seat 40 immediately separates from the valve portion 41c and opens both working chambers 2b.
, 3b are communicated with the atmosphere inlet 33. As a result, the atmosphere flows from the atmosphere inlet 33 to the second valve seat 40 and the first boat 14.
is quickly introduced into both working chambers 2b, 3b through the chamber 2.
Since the pressure in the pressure chambers b and 3b is higher than that in the pressure chambers 2a and 3a, a large forward force is obtained based on the pressure difference between them, and both booster pistons 4 and 6 resist the force of the return spring 23, as shown in FIG. The piston 55 of the brake mask cylinder M is driven forward via the output rod 53. In this way, the brake mask cylinder M is connected to the brake pedal 3.
It can be activated without delay when the pedal is pressed down, and the brakes can be applied to the vehicle. At this time, the second
Since the passage 15c of the port 15 is located at the rear end of the rear negative pressure chamber 3a, a sufficient stroke of the piston boss 10, that is, a stroke of the piston 55 can be ensured.

During such braking, the valve piston 38 along with the input rod 35
However, the elastic piston 50 bulges and deforms toward the small cylinder hole 36 side due to the actuation reaction force of both booster pistons 4.6, and the reaction force Since a part of the reaction force is applied to the piston 52, the force is fed back to the brake pedal 34 via the valve piston 38 and 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 5.3 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 increased. It is transmitted to the output rod 53 via the valve piston 38, piston boss 10, elastic piston 50, and output piston 51, and in the end, the sum of the forward force due to the pressure difference of each booster piston 4.6 and the forward force due to the input. is output from the output rod 53.

Next, when the pressure on the brake pedal 34 is released,
First, the input rod 35 retreats together with the valve piston 38 due to the elastic force of the return spring 45, and the second valve seat 40 is moved against the valve 84 of the valve body 41.
1C and the valve portion 41c is spaced apart from the first valve seat 39, both the working chambers 2b, 3b communicate with the surface pressure chambers 2a, 3a, and the pressure difference between the front and rear of each booster piston 4, 6 is immediately eliminated. Therefore, both booster pistons 4 and 6 move back with the elastic force of the return spring 23, and the operation of the brake mask cylinder M is released.

Then, when the input rod 35 returns to the backward limit where the stopper plate 46 contacts the partition wall 26a of the extension tube 26, the rear booster piston 6 first contacts the protrusion 24 of the rear diaphragm 7 with the rear wall of the booster shell 1. This time, the first valve seat 39 is seated on the valve seat 41c, and the valve portion 41c is seated on the second valve seat 40. Since the atmosphere is moved slightly away from the working chambers 2b and 3b, the atmosphere is again introduced into the working chambers 2b and 3b, but due to the resulting pressure difference, if both the booster pistons 4.6 move forward a little, the space between the second valve seat 40 and the valve part 41c increases. The small gap disappears, leaving the control valve 32 in its initial neutral state. In this way, the negative pressure diluted with the atmosphere is maintained in both working chambers 2b and 3b, and the negative pressure booster B enters the rest state as shown in FIG.

In such a tandem type negative pressure booster B, in order to fix the front and rear booster pistons 4.6 and the front and rear diaphragms 5, 7 to the piston boss 10, first, the front booster piston is attached to the flange 10a of the piston boss 10. 4
After fitting the inner peripheral end of the sleeve 12 with the inner peripheral bead 5a of the front diaphragm 5 from the rear, the front booster piston 4 and the diaphragm 5 are clamped and fixed with the front end of the sleeve 12 inserted from the rear. At this time, the convex portion 12a formed on the sleeve 12 engages with the concave portion 10d formed on the piston boss 10, thereby restricting relative rotation between the sleeve 12 and the piston boss 10. Also, since the sealing member 9 provided on the partition wall plate 1c is bent forward, that is, toward the inside of the front working chamber 2b, by the front end of the sleeve 12 inserted from the rear, the front working chamber on the high pressure side Pressure leakage from 2b to the rear negative pressure chamber 3a on the low pressure side is effectively prevented. Next, the inner peripheral end of the rear booster piston 6 and the inner peripheral bead 7a of the rear diaphragm 7 are attached to the stepped portion 10b of the piston boss 10.
After fitting from the rear, attach the set ring 13 to the rear.
Attach. Thereby, the rear booster piston 6 and the rear diaphragm 7 are clamped and fixed between the rear end of the sleeve 12 and the set ring 13.

When the sleeve 12 is fixed to the piston boss 10 as described above, the piston boss 10 and the sleeve 1
A first boat 14 is defined by the cooperation of the piston boss 10, the sleeve 12, and the rear booster piston 6, and a second boat 15 is defined by the cooperation of the piston boss 10, the sleeve 12, and the rear booster piston 6. The O-ring 16 disposed between the outer circumference of the piston boss 10 and the inner circumference of the sleeve 12 and the inner circumferential bead 5a of the front diaphragm 5 connect the first port 14 and the front and rear negative pressure chambers 2a.
, 3a, and at the same time, the ○ ring 16 and the inner peripheral bead 7a of the rear diaphragm 7 prevent communication between the second boat 15 and the front and rear working chambers 2b.

3b communication is blocked.

C6 Effects of the invention As described above, according to the present invention, when fixing the inner peripheral ends of the front and rear booster pistons and the inner peripheral beads of the front and rear diaphragms to the piston boss, the sleeve that fits into the piston boss and the Since only two members, the stopper member attached to the piston boss, need to be used, the number of parts can be reduced compared to the conventional method using multiple through bolts, and the assembly time can be significantly reduced. It is possible to shorten the time to

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a longitudinal cross-sectional side view of a tandem negative pressure booster in a rest state, and FIGS. ■ Line cross section, 4th
The figure is a partial longitudinal sectional side view showing the operating state of the negative pressure booster. 1... Booster shell, 1c... Bulkhead plate, 2...
Front shell chamber, 2a... Front negative pressure chamber, 2b... Front working chamber, 3... Rear shell chamber, 3a... Rear negative pressure chamber, 3b... Rear working chamber, 4 ...Front booster piston, 5...Front diaphragm, 5a...Inner circumference bead, 6...Rear booster piston, 7...Rear diaphragm, 7a...Inner circumference bead, 10...・Piston boss, 10a...flange, 12...sleeve, 13
...Set ring (stopper member), 25...Valve cylinder, 32...Control valve, 35...Input rod, 53-...Output rod Patent Applicant: Nissin Kogyo Co., Ltd.

Claims (1)

[Claims] The booster shell (1) has a front shell chamber (
A bulkhead plate (1c) is fixedly installed to partition the front shell chamber (2) into the front negative pressure chamber (2a) and the rear shell chamber (3).
) and a front working chamber (2b) on the rear side, a front diaphragm (5) superimposed on the rear surface thereof, and a rear shell chamber (3) on the front rear negative pressure. A rear booster piston (6) partitioned into a chamber (3a) and a rear rear working chamber (3b) and a rear diaphragm (7) superimposed on the rear surface are outputted by passing through the partition plate (1c). A valve cylinder connected to the rod (53) via a piston boss (10), connected to the rear end of the piston boss (10), and slidably supported on the rear wall of the booster shell (1). (25) includes an input rod (35) that can move forward and backward;
Both working chambers (2b,
In a tandem negative pressure booster equipped with a control valve (32) for switching communication between the air and the negative pressure chambers (2a, 3a), the sleeve is slidably supported on the bulkhead plate (1c). (12
) is fitted onto the outer periphery of the piston boss (10), and the front end of the sleeve (12) and the flange (10a) provided on the piston boss (10) are connected to the inner periphery and front part of the front booster piston (4). Inner peripheral bead (5a) of diaphragm (5)
is clamped and fixed to the front part of the piston boss (10), and the stopper member (
13) and the rear end of the sleeve (12) clamp the inner cylindrical end of the rear booster piston (6) and the inner peripheral bead (7a) of the rear diaphragm (7) and fix it to the rear of the piston boss (10). A tandem negative pressure booster featuring: