JPH0347014Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a pneumatic booster that is placed between a brake or clutch master cylinder and a pedal in a vehicle, etc., and is used to increase the hydraulic pressure of the master cylinder. .

Conventionally, this type of pneumatic booster has a main body having a space inside, a movable wall movably inserted into the space, a low pressure chamber and a high pressure chamber partitioned in front and behind the movable wall, and the above-mentioned. a preload spring that biases the movable wall rearward; a cylindrical hub member that forms a part of the movable wall and whose rear portion movably penetrates the main body and protrudes to the outside; an output shaft and an input shaft that fit into the inner hole from both sides, respectively;
a plunger disposed between the two shafts so as to be movable integrally with the input shaft; and a valve device provided in association with the plunger that opens and closes to create a pressure difference between the low pressure chamber and the high pressure chamber. , a stopper member that limits the movement range of the plunger by engaging with the plunger, and the valve device reduces the differential pressure from the differential pressure eliminating position by moving the input shaft relative to the movable wall. There is known a device that switches from a holding position to a differential pressure generating position.

However, with such conventional devices, there is a problem in that there is a delay in operation between when the pedal is depressed and when hydraulic pressure is actually generated in the master cylinder. There is play in each part, that is, play in the master cylinder itself, play in the booster itself, play between the master cylinder and booster, and play in the connecting parts of each part, and the sum of these plays is This is because it is quite large.

In order to reduce such play, various methods have been proposed in which the input shaft is advanced a little in advance beyond its retraction limit by providing a stopper means for limiting the position. According to each of these proposed methods, the stopper means for limiting the position is connected to the input shaft with a member whose positional relationship is fixed with the vehicle body, such as the housing of the booster or the stopper for regulating the return position of the pedal. is set between.

By the way, in the case where the stopper means for limiting the position is provided between the housing of the booster and the input shaft, it has the advantage that the return position of the pedal does not change. There is a problem in that a large amount of space is required between the rear of the housing of the device and the pedal. To make this more clear with a concrete example, as a technique described in Japanese Patent Publication No. 57-53220, a covering tube is formed at the rear of the housing of the booster to cover the input shaft.
It is known that a movable stopper means is provided between the inner surface of the rear end wall of the covering tube and the input shaft to adjust the forward and backward limit. However, with this technology, since the sheathing tube is a rigid body, extra space is required to avoid interference between the pedal and the housing of the booster, and the axial direction required for installing the booster is limited. A problem arises in that the space required is larger than that without a covering tube.

This invention was made in consideration of the above points, and its purpose is to provide a stopper means for limiting the position at the rear of the housing of the booster without causing space problems. An object of the present invention is to provide a pneumatic booster.

Other objectives and novel features of this invention are:
It will become clear from the description of this specification and the accompanying drawings.

In this invention, the above-mentioned space problem is avoided by making the stopper member interposed between the housing of the booster and the input shaft movable with respect to the housing. To be more specific, a cylindrical member is provided separately from the main body of the housing, and the cylindrical member can be moved forward and backward relative to the main body like the tube of a telescope.

Hereinafter, the content of this invention will be clarified by describing one embodiment shown in the accompanying drawings.

The accompanying drawing is a side sectional view showing the overall configuration of a negative pressure booster that is an embodiment of this invention. In addition,
Components in the figures that are substantially the same as those in the prior art will be briefly explained. Further, the front-rear direction is the left-right direction in the figure.

The negative pressure booster 1 has a main body 6 which is formed by combining a front shell 4 and a rear shell 5 with an outer peripheral bead 3 of a diaphragm 2 in between. This main body 6 forms the housing of the booster. A movable wall 10 formed by joining a plate member 8 and a hub member 9 via the inner peripheral bead portion 7 of the diaphragm 2 is disposed within the main body 6 so as to be freely movable. This movable wall 10 works together with the diaphragm 2 to move the main body 6
There is a low pressure chamber 11 on the front side of the interior, and a high pressure chamber 1 on the rear side.
2 respectively. The main body 6 is supported by fixedly attaching the rear shell 5 to the vehicle body (not shown), and a master cylinder (not shown) is closely attached to the front side of the main body 6. The hub member 9 is generally cylindrical, and the rear portion 91 has a smaller diameter than the front portion 92, and the smaller diameter rear portion 91 passes through the central hole 34 of the rear shell 5 and projects to the outside.

An output shaft 15 is inserted into the stepped inner hole 13 passing through the center of the hub member 9 through a retainer 14 at its front end.
are fitted, and the front end of the output shaft 15 is brought into contact with the bottom of the recess at the rear of the piston of the master cylinder.
Behind the output shaft 15 is a rubber disk 16, a plunger 17, and an input shaft 1 coupled to the plunger 17 so as to be able to swing and to be prevented from coming off in the axial direction.
8 are arranged respectively. The plunger 17 has a hole 19 running in the radial direction and communicating with the inner hole 13 on the inside.
The amount of axial movement is limited to a predetermined range, which will be described later, by a U-shaped stopper member 20 inserted therein.
Valve seat 21 provided on the outer periphery of the rear end of the plunger 17
A poppet valve member 23 is disposed so as to be able to sit on and face a valve seat 22 formed in a stepped portion of the stepped inner hole 13 on the radially outer side thereof. The poppet valve member 23 has its rear end engaged with a step on the rear side of the stepped inner hole 13, and a front portion 230 of the poppet valve member 23.
is movable. Between the poppet valve member 23 and the input shaft 18, there is a conical spring-shaped first portion 241 that biases the input shaft 18 rearward and a front portion 230 of the poppet valve member 23 that biases the front side portion 230 of the poppet valve member 23 forward. A valve spring 24 that is integrally formed with the second portion 242 is stretched. The outer periphery of the front portion 230 of the poppet valve member 23 is constantly connected to the low pressure chamber 11 through a passage 25 provided in the hub member 9, and is further connected to a negative pressure source such as an engine intake manifold through a pipe (not shown). Ru. On the other hand, the inner peripheral side of the poppet valve member 23 is constantly in communication with the atmosphere through a filter 26 disposed at the opening of the stepped inner hole 13. Further, the outer periphery of the plunger 17 on the front side of the poppet valve member 23 is always in communication with the high pressure chamber 12 through a passage 27 of the hub member 9.

These poppet valve members 23 and plungers 17
The valve device A is constituted by the above. Valve device A
is a state in which the poppet valve member 23 is seated on the valve seat 21 and separated from the valve seat 22, in other words,
The low pressure chamber 11 and the high pressure chamber 12 are connected to each other, and the high pressure chamber 12
The state in which the communication with the atmosphere is cut off is the hyperbaric chamber 1.
2 and the low pressure chamber 11, and the poppet valve member 23 is seated on the valve seats 21 and 22. In other words, the poppet valve member 23 is seated on the valve seats 21 and 22. The state in which both the communication and the communication between the high pressure chamber 12 and the atmosphere are cut off is the differential pressure holding position in which the differential pressure between the high pressure chamber 12 and the low pressure chamber 11 is kept constant, and the poppet valve member 23 is moved away from the valve seat 21. A state of being unseated and seated on the valve seat 22,
In other words, a state where the low pressure chamber 11 and the high pressure chamber 12 are disconnected from each other and the high pressure chamber 12 and the atmosphere are in communication is a differential pressure generation position where a differential pressure is generated. Particularly, at the differential pressure generating position and the differential pressure eliminating position, ranges of these positions are set at both ends of the movement range of the plunger 17 with respect to the movable wall 10. A threaded portion 28 is provided at the rear end of the input shaft 18, and a clevis 29 is screwed thereto, and a pedal (not shown) is pin-coupled to a hole 30 at the rear end of the clevis 29. A nut 31 on the front side of the clevis 29 is for preventing loosening.

By the way, such a booster 1 has a movable wall 1.
A preload spring 32 is tensioned between the front shell 4 and the movable wall 10 for biasing the rearward direction. Therefore, when inactive, the movable wall 10 is biased rearward by this strong preload spring 32, and the rib 33 of the diaphragm 2 is in contact with the inner surface of the rear shell 5. At this time, the plunger 17 and the input shaft 18 are urged rearward by the valve spring 24, and therefore, conventionally, the poppet valve member 23 is seated on the inner valve seat 21; Unlike the previous state, the valve seat 22 was separated from the outer valve seat 22.
The distance between the poppet valve member 23 and the valve seat 22 is the main cause of play in the booster 1.

Therefore, in order to eliminate such operational play in the booster 1, it is effective to seat the poppet valve member 23 on both the inner and outer valve seats 21 and 22 in the non-operating state. For that,
The input shaft 18 may be moved forward relative to the movable wall 10 by the distance.

In this invention, the cylindrical member 35 is slidably fitted to the outer periphery of the rear portion 91 of the hub member 9 extending behind the movable wall 10, and the front end side of the cylindrical member 35 is connected to the rear shell 5. The rear end side of the cylindrical member 35 defines the position of the input shaft 18 at its rear end.

The small-diameter rear portion 91 of the hub member 9 passes through the central hole 34 of the rear shell 5 and projects to the outside, as described above. The rear part of the rear shell 5 is narrower than the front part, and a hole 34 is formed inside the narrowed part 51. However, the hole 34 has a larger diameter than the rear portion 91, and there is a sufficient gap between the outer peripheral surface of the rear portion 91 and the inner peripheral surface of the throttle portion 51. Therefore, the rear portion 91 is the hole 3.
4, the hub member 9, that is, the movable wall 10, is movable in the front-back direction.

The cylindrical member 35 is slidably fitted to the outer periphery of the rear portion 91 of the hub member 9 in a shape that matches the outer shape of the rear portion 91. The cylindrical member 35 is
It covers the entire length of the small-diameter rear portion 91, and has an outward facing flange 3 on the front end side at both ends.
6. An inward flange 37 is provided on each rear end side. The outward flange 36 on the front end side constitutes a protrusion that can come into contact with the main body 6, and its outer diameter is larger than the hole 34. In addition, the inward flange 37 on the rear end side constitutes a protrusion that can be abutted in the direction of advancing the input shaft 18, and its inner diameter is in contact with the rear surface of the stepped portion 38 in the middle of the input shaft 18. It is smaller than the outer diameter of the stopper ring 39. In this case, the outward flange 36 on the front end side is set so as to come into contact with the inside surface of the rear shell 5 in the illustrated non-operating state in which the rib 33 of the diaphragm 2 comes into contact with the inside surface of the rear shell 5 . Then, in the same state, the inward flange 3 on the rear end side of the cylindrical member 35
7 is set at a position where the input shaft 18 can be advanced by a predetermined amount against the biasing force of the valve spring 24.
Of course, the predetermined amount corresponds to the amount of separation between the poppet valve member 23 and the valve seat 22 described above. Note that while the hub member 9 is made of plastic, the cylindrical member 35 is made of a metal with high mechanical strength. It also has the function of protecting the

Next, making the hole 34 airtight will be briefly explained. The cylindrical member 35 is located at the rear portion 91 of the hub member 9.
Since the cylindrical member 35 is slidably fitted into the cylindrical member 35, it is necessary to make the cylindrical member 35 airtight not only on the outer periphery side but also on the inner periphery side. Airtightness on the inner circumferential side of the cylindrical member 35 is maintained by a seal ring 40 set in a groove on the outer circumference of the rear portion 91 of the hub member 9, and airtightness on the outer circumferential side is maintained by a boot 41. The front end portion 42 of the boot 41 is connected to the constricted portion 51 of the rear shell 5.
and the cylindrical member 35, while the rear end portion 43 is supported by being hooked onto an inward flange 37 on the rear end side of the cylindrical member 35. Further, in order to prevent the front end portion 42 of the boot 41 from slipping out and to prevent it from slipping, the rear end of the constricted portion 51 of the rear shell 5 is bent inward. Ring 44 and retaining ring 45 made of elastic material
is provided.

Now, in the booster 1 according to this invention,
Due to the stopper function of the cylindrical member 35, the retraction limit of the input shaft 18 is slightly advanced, so that the poppet valve member 23 is seated on both the inner and outer valve seats 21 and 22 when not in operation. become. This means that the operating play in the booster 1 itself has been eliminated.

Therefore, when the input shaft 18 is moved forward by depressing a pedal (not shown), the valve device A is immediately switched to the differential pressure generating position. Then, the movable wall 10 moves forward against the force of the preload spring 32 due to the differential pressure, and the output shaft 15 moves toward the movable wall 10 via the rubber disk 16.
The pressing force, which is the sum of the moving force of the input shaft 18 and the moving force (input) of the input shaft 18, advances a piston of a master cylinder (not shown) to generate pressure. Then, when the moving force (input) of the input shaft 18 and the reaction force acting on the plunger 17 from the rubber disk 16 are balanced, the valve device A switches to a differential pressure holding device, and the pressure generated in the master cylinder becomes constant. .

During this time, the cylindrical member 35
Generally, the movable wall 10 moves forward together with the rear portion 91 due to the frictional force caused by the movable wall 10, and at least the outward flange 36 at the front end part separates from the inner surface of the rear shell 5. Therefore, the cylindrical member 35 can avoid interference with the pedal by the amount that it moves forward.
Furthermore, even if the pedal interferes with the cylindrical member 35 via the boot 41, the cylindrical member 35 is movable relative to the movable wall 10, so it will move forward according to the force from the pedal, and the pedal will move forward in response to the force from the pedal. There will be no problem that would restrict the pedal stroke.

On the other hand, when the pedal is no longer depressed, the input shaft 18 is returned to the rear by the force of the valve spring 24. This backward movement force is caused by the stopper ring 39
It is also transmitted to the cylindrical member 35 via the cylindrical member 35.
will also retreat as well. Such retreat progresses until the outward flange 36 on the front end side of the cylindrical member 35 comes into contact with the inner surface of the rear shell 5. Further, as the input shaft 18 retreats, the plunger 17 integrated therewith also retreats, so that the valve device A is switched to the differential pressure eliminating position. This switching state continues until the rear end surface of the rear portion 91 of the movable wall 10 comes into contact with the front surface of the inward flange 37 of the cylindrical member 35. Therefore, the atmosphere in the high pressure chamber 12 sufficiently moves toward the low pressure chamber 11 side, and both chambers 12 and 11 on both sides of the movable wall 10 have approximately the same pressure. As a result, each member returns to its pre-operation state as shown.

Although this invention has been specifically explained above based on examples, it goes without saying that this invention is not limited to the above-mentioned examples and can be modified in various ways without departing from the gist thereof. Examples of changes are as follows.

(1) Instead of the stopper ring 39, a nut screwed to the input shaft 18 can be used. By doing so, the relative advance amount of the input shaft 18 can be adjusted, so that the poppet valve member 23 can be reliably seated on both the inner and outer valve seats 21 and 22 during non-operation.

(2) By providing a groove of a predetermined length running in the front-rear direction on the outer periphery of the rear portion 91 of the hub member 9, and providing a protrusion that fits into the groove on the inner periphery of the cylindrical member 35, the hub member 9 cylindrical member 3
The range of movement of 5 can be limited. Then, when the pedal is depressed, the input shaft 18
When moving forward, the cylindrical member 35 can reliably follow the movable wall 10.

[Brief explanation of the drawing]

The drawing is a side sectional view showing the overall structure of a booster which is an embodiment of this invention. DESCRIPTION OF SYMBOLS 1... Booster, 6... Main body, 9... Hub member, 91... Rear part, 10... Movable wall, 11...
...Low pressure chamber, 12...High pressure chamber, 13...Inner hole, 15
... Output shaft, 17 ... Plunger, 18 ... Input shaft, 19 ... Hole, 20 ... Stopper member, 32 ...
...Preload spring, 35... Cylindrical member, 36... Outward flange (protrusion), 37... Inward flange (protrusion), A... Valve device.

Claims (1)

[Scope of utility model registration request] A main body having a space inside, a movable wall movably inserted into the space, a low pressure chamber and a high pressure chamber partitioned in front and behind the movable wall, and a preload spring that biases the movable wall rearward. a cylindrical hub member that forms part of the movable wall and whose rear portion movably penetrates the main body and protrudes to the outside; an output shaft and an input that fit into inner holes of the hub member from both sides; a shaft, a plunger disposed between the two shafts so as to be movable integrally with the input shaft; and a plunger provided in relation to the plunger, which opens and closes to create a pressure difference between the low pressure chamber and the high pressure chamber. a valve device; and a stopper member that limits the movement range of the plunger by engaging with the plunger, and when the input shaft moves forward relative to the movable wall, the valve device is moved to a differential pressure eliminating position. In a pneumatic booster configured to switch from a differential pressure holding position to a differential pressure generating position, a cylindrical member separate from the main body covers the outer periphery of the rear portion of the hub member, and the cylindrical member penetrates the main body and a part thereof protrudes outside the main body, and the cylindrical member can move forward and backward with respect to the main body, and the movable wall returns to the front end side of the cylindrical member. A pneumatic booster comprising a protrusion that can come into contact with the main body when the main body is in the position, and a protrusion that can come into contact with the input shaft on the rear end side in a direction in which the input shaft advances.