JPS6114982B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a pneumatic booster used in a brake device or the like.

(Prior Art) Some pneumatic boosters that perform a boosting action using the negative pressure in the intake pipe of an engine include a reaction disk made of a pressurized deformable member such as an elastic body. To explain this with reference to FIG. 4, the main body 41
The interior is divided into two chambers, a front chamber 44 and a rear chamber 45, by a diaphragm 42 and a power piston 43 attached to the diaphragm 42, and an input shaft 46
When the power piston 43 is operated to generate a pressure difference between the two chambers 44 and 45, the forward thrust generated in the power piston 43 is transmitted to the output shaft 48 via the reaction disk 47, while the output shaft The reaction force from 48 is transmitted to the input shaft 46 via the reaction disk 47.

The structure of the reaction disk part in this type of conventional pneumatic booster, that is, the reaction force mechanism, is as follows:
A recess 49 is provided in the front surface of the power piston 43,
The reaction disk 47 is housed here and is fitted into the rear end 48a of the output shaft 48, and the power piston 43 is formed with a hole that communicates with the recess 49 and has a smaller diameter than the recess 49. A plunger 51 provided on the front end shaft of the input shaft 46 faced the hole 50. Therefore, the thrust of the power piston 43 is transmitted from the stepped portion 43a of the power piston 43 formed between the recess 49 and the hole 50 to the output shaft 48 via the reaction disk 47, while the output The reaction force from the shaft 48 deforms as the reaction disk 47 is pressurized, and a part of it protrudes into the hole 50, and this protrusion comes into contact with the plunger 51, so that the input shaft 46
This will be communicated to

(Problems to be solved by the invention) However, like the above-mentioned conventional booster,
Power piston 43 and reaction disk 47
If power is transmitted directly between the power piston 43 and the power piston 43, there is a problem in durability since the power piston 43 is usually made of weakly strong synthetic resin. This is even more undesirable since force is locally transmitted at the stepped portion 43a formed in the step portion 43a. In addition, the output shaft 4
Part of the reaction force No. 8 will be transmitted to the power piston 43 and the remaining part will be transmitted to the input shaft 46. In order to change the ratio of the magnitude of the reaction force (hereinafter referred to as boost ratio), the boost ratio is determined by the area of the portion of the output shaft 48 that contacts the reaction disk 47 and the reaction disk 47.
Since it is determined by the area ratio between the area of the hole 50 and the area of the hole 50 from which the power piston 4 is deformed and a part thereof protrudes, it is necessary to change the area ratio.
3, the size of the recess 49 formed in the recess 49 and the hole 50 communicating with the recess 49 must be changed, that is, the entire power piston 43 must be changed. There was a problem that it was troublesome and the cost was high.

The present invention has been made in view of these problems, and an object of the present invention is to provide a pneumatic booster that can increase the durability of a power piston and easily change the boost ratio.

(Means for Solving the Problems) The technical means of the present invention for solving the above problems is that a diaphragm 2 and a power piston 3 attached to the diaphragm 2 connect the inside of the main body 1 to the float chamber 4 and the rear. A thrust force generated in the power piston 3 in the forward direction, that is, toward the front chamber 4 side, when the input shaft 8 is actuated to create a pressure difference between the two chambers 4 and 5. In this pneumatic booster, the power is transmitted to the input shaft 8 via a reaction disk 16 made of a pressurized deformable member such as an elastic body. Synthetic resin valve body 7
A reaction plate 13 is provided, the outer circumference of which comes into contact with the plate 13, and a hole 13a is bored in the plate 13 for guiding the head 9b of the plunger 9 provided at the front end of the input shaft 8. A spring retainer 14 having a cylinder portion 14a having a larger diameter than the guide hole 13a is disposed on the front surface of the plate 13, and inside the cylinder portion 14a,
It is characterized in that the reaction disk 16 is housed therein, and the rear end portion 17a of the output shaft 17 is fitted therein.

(Function) In the booster of the present invention, when the input shaft 8 is operated to generate a differential pressure on both sides of the diaphragm 2, a forward thrust is generated in the power piston 3,
The thrust of the power piston 3 is transmitted from the reaction plate 13 to the output shaft 17 via the reaction disk 16. When the thrust force is transmitted to the output shaft 17, a reaction force is generated in the rearward direction on the output shaft 17. This reaction force of the output shaft 17 is transmitted to the reaction plate 1 via the reaction disk 16.
3 to the power piston 3.

On the other hand, the reaction disk 16 is pressurized and deformed due to the reaction force from the output shaft 17, and a part of the deformed portion is inserted into the guide hole 1 of the reaction plate 13.
3a, thereby pressing the head 9a of the plunger 9 and transmitting it to the input shaft 8.

As described above, in the device of the present invention, the reaction plate 13 having the guide hole 13a for the plunger 9 is disposed between the power piston 3 and the reaction disk 16. The force is transmitted indirectly through the reaction plate 13. Therefore, strong local force is not concentrated at the center of the power piston 3. Since the reaction plate 13 is in contact with the valve body 7 on the outer circumference of the power piston 3 over a large area, the stress load received from the reaction disk 16 of the power piston 3 is dispersed on the outer circumference of the power piston 3 and is substantially reduced. This increases the strength and durability of the power piston 3.

Furthermore, when a pressure difference occurs on both sides of the diaphragm 2, the force that this pressure difference exerts on the power piston 3 is:
The size increases from the center to the outer circumference of the power piston 3, but since the valve body 7 on the outer circumference of the power piston 3 is received by the reaction plate 13, the valve body 7 is made of synthetic resin. Also, it does not deform and has an advantageous effect on strength.

Next, the case of changing the boost ratio in the device of the present invention will be described. As mentioned above, this boosting ratio is the ratio of the magnitude of the reaction force transmitted to the input shaft 8 to the magnitude of the reaction force from the output shaft 17. This is determined by the ratio between the area of the contacting portion and the area of the guide hole 13a from which the reaction disk 16 deforms and partially protrudes. Cylinder part 14
The reason why a has a larger diameter than the hole 13a has a technical meaning in order to obtain a boost ratio. Therefore, in the present invention, the plunger 9, output shaft 17,
Just replace it with the reaction disk 16. In this case, since the power piston 3, which is a large component, can be used as is without any replacement as in the conventional case, the boost ratio can be easily changed.

(Example) Examples of the present invention will be described below with reference to the drawings. In FIG. 1 showing a first embodiment of the present invention, a front shell 1A and a rear shell 1B constitute a main body 1 having a sealed space inside.
It is divided into two chambers, a front chamber 4 and a rear chamber 5, by a power piston 3 attached to the front chamber. This front chamber 4 is connected to a negative pressure generating section such as an engine intake pipe. Also, the power piston 3 is
In this embodiment, the valve body 6 is composed of a synthetic resin valve body 6 and a metal piston plate 7, which are integrated by a coupling means such as fitting between the inner end of the diaphragm 2.

The valve body 6 extends outside the main body 1 by airtightly passing through the rear shell 1B, and also extends from the rear shell 1B.
The piston plate 7 is movable in the left and right directions in the figure (hereinafter referred to as the front and rear directions) with respect to Therefore, when a pressure difference occurs between the two chambers 4 and 5, the pressure difference is substantially received.

An input shaft 8 is inserted into the valve body 6, and its rear end is connected to a brake pedal (not shown), and its spherical front end is connected to the valve body 6.
The plunger 9 is fitted into a recess of a plunger 9 which is slidably fitted into the cylinder portion 6a of the plunger 9, so that both 8 and 9 are integrally connected so as to be swingable. Therefore, when the brake is applied, the plunger 9 is pressed forward, that is, in the direction in which the power piston 3 generates thrust. The cylinder portion 6a into which the plunger 9 is fitted opens into the front chamber 4, and the front end portion 9b of the plunger 9, which is a small diameter portion, slightly protrudes into the front chamber 4. Then, the retaining ring 10 fitted to the plunger 9 is attached to the valve body 6.
By contacting the front surface of the valve body 6a, that is, the opening edge of the cylinder portion 6a, the plunger 9 is prevented from moving backward by a predetermined amount or more with respect to the valve body 6.

Valve seats 6b and 9a are formed at the rear ends of the cylinder portion 6a of the valve body 6 and the plunger 9, respectively, and as the plunger 9 moves, the poppet valve 12, which is pressed by the spring 11, opens the valve. The poppet valve 12 is in contact with and separated from the seats 6b and 9a, but when it is not in operation, as shown in the figure, the poppet valve 12 is in contact with the valve seat 9a but is separated from the valve seat 6b. The front chamber 4 and the rear chamber 5 are passages 6c and 6 of the valve body 6.
d, while the two chambers 4 and 5 are cut off from the atmosphere (the area behind the poppet valve 12 in the valve body 6 communicates with the atmosphere).

A reaction plate 13 made of metal and a spring retainer 14 as a cylinder member are sequentially arranged on the front surface of the piston plate 7, and a plurality of claws 7a formed by cutting and raising a part of the piston plate 7 are connected to the spring retainer 14. By inserting and locking into a plurality of openings 14c formed in the piston plate, the reaction plate 13 is regulated in a radial position with the claw portion 7a surrounding the reaction plate 13, and the spring retainer 14 is inserted into the piston plate. 7 in place. In addition, the reaction plate 13 and the spring retainer 14
After integrating the two by, for example, welding, the two 1
3 and 14 may be held by the piston plate 7.

The reaction plate 13 is generally formed into an annular shape with its central part bulging slightly forward, its outer peripheral edge abuts against the piston plate 7 over a large area, and its central part is spaced apart from the piston plate 7. The front end 9b of the plunger 9 faces a hole 13a opened in the center of the reaction plate 13. In this case, the front end 9b of the plunger 9 may be fitted into the hole 13a from the beginning, or it may not be fitted when the plunger 9 is not in operation, but may be fitted when the plunger 9 moves forward during the operation. However, in terms of operational stability,
The former is preferable. Further, this hole 13a and the front end portion 9b of the plunger 9 have approximately the same diameter.

The spring retainer 14 is also formed approximately in an annular shape, and has a cylinder portion 14a extending forward in the center thereof.
is formed by drawing, and the cylinder portion 14a
has the same axis as the hole 13a of the plunger 9, that is, the reaction plate 13, and has a larger diameter than the hole 13a. A return spring 15 is stretched between the peripheral edge of the spring retainer 14 and the front shell 1A, and the return spring 15 causes the power piston 3 to move in the return direction (rearward direction) via the spring retainer 14 and the reaction plate 13. ).

Inside the cylinder portion 14a of the spring retainer 14, a reaction disk 16 as a pressurized deformable member formed of an elastic body such as rubber is housed.
A rear end portion 17a, which is an enlarged diameter portion, of the output shaft 17 is slidably inserted at a position further forward than the rear end portion 17a of the output shaft 17. The output shaft 17 is disposed so as to have the same axis as the plunger 9, and its front end 17b passes through the front shell 1A airtightly and movably in the front and back direction by means of a seal 21, and extends outside the main body 1. The front end portion 17b is connected to a piston of a master cylinder (not shown).

Note that the cylinder portion 1 of the spring retainer 14
The front end portion of the output shaft 17 is folded inward to form an annular locking portion 14a, and the locking portion 14b prevents the rear end portion 17a of the output shaft 17 from moving forward within the cylinder portion 14a by more than a predetermined amount. It's getting old.

In the booster configured as described above, when the brake pedal is depressed, the spring 22
When a forward thrust is applied to the input shaft 8 against the applied force of the stationary valve body 6,
The poppet valve 12 pushed by the plunger 9 and the spring 11 moves forward, and the poppet valve 12 comes into contact with the valve seat 6b of the valve body 6, cutting off communication between the front chamber 4 and the rear chamber 5.

When the input shaft 8 is further pressed, the valve seat 9a of the plunger 9 is separated from the surface of the poppet valve 12, and at the same time, the atmosphere enters the rear chamber 5 through the gap and the passage 6b.

The introduction of this atmospheric pressure creates a pressure difference on both sides of the diaphragm 2, which generates forward thrust in the power piston 3 and starts boosting operation.The thrust of the power piston 3 is then transferred to the reaction The pressure is transmitted from the inner circumferential edge 13b of the plate 13 to the output shaft 17 via the reaction disk 16, and as a result, the output shaft 17 is pushed forward and hydraulic pressure is generated in the master cylinder.

At this time, the rearward reaction force acting on the output shaft 17 is transmitted to the power piston 3 from the inner peripheral edge 13b of the reaction plate 13 via the reaction disk 16, while the reaction disk 16 pressurizes the As a result, a portion thereof protrudes into the hole 13a of the reaction plate 13 and comes into contact with the plunger 9, and as a result, it is transmitted to the brake pedal via the plunger 9 and the input shaft 8.

Due to the forward movement of the power piston 3 in conjunction with the forward movement of the diaphragm 2, the valve seat 9a of the plunger 9 comes into contact with the poppet valve 12, and becomes stationary.
If the brake pedal is further depressed, a similar operation will occur.

At this time, in the conventional mechanism, the reaction force from the output shaft 17 acts on the center part of the power piston 3, and the force due to the differential pressure increases as it moves toward the outer circumference of the power piston 3, so it corresponds to the power piston plate 7 part. However, in the present invention, the outer periphery of the reaction plate 13 is brought into contact with the outer periphery of the power piston 3. Because it can be brought into contact with
The above-mentioned unnecessary bending moment does not act on the power piston 3, so that it is possible to obtain a piston with excellent strength.

Therefore, for the above reasons, if the piston plate 7 is not provided separately and instead the outer periphery of the valve body 6 is extended in the radial direction in the form of a flange and placed in front of the diaphragm 2, the rear axle The outer circumferential edge of the reaction plate 13 may be further extended in the radial direction so that the outer circumferential edge of the reaction plate 13 comes into contact with the entire surface of the flange-shaped portion of the bulb body 6. Further, without changing the area of the portion of the reaction plate 13 that contacts the power piston, the contact position between the two may be moved further outward in the radial direction.

When the brake pedal is released, the return spring 15 causes the diaphragm 2 and the power piston 3 to return to their original positions as shown. When the power piston 3 returns, if the return of the power piston 3 is faster than the return of the piston of the master cylinder, the output shaft 17 will keep moving forward due to the sliding resistance of the front seal 21. However, as mentioned above, the locking part 14b of the spring retainer 14 returns the rear end 17a of the output shaft 17 to the rear, so the output shaft 17 eventually becomes a power piston. It will return to the original position together with 3, and will not fall off.

Here, in order to change the boost ratio, as understood from the above explanation, in addition to replacing the output shaft 17 and the reaction disk 16, the diameter of the cylinder portion 14a of the spring retainer 14 and the reaction plate must be changed. It is only necessary to change one (or both) of the diameters of the 13 holes 13a. For this purpose, either one (or both) of the reaction plate 13 and the spring retainer 14 is replaced, and the plunger 9 or output shaft 1 fitted therewith is replaced.
7. It is only necessary to replace the reaction disk 16 with a corresponding one, and the power piston 3, which is a large component, does not require any changes.

FIG. 2 shows another embodiment of the present invention, in which a cylindrical sleeve 18 having the same diameter is removably fitted into the cylinder portion 14a of the spring retainer 14 over its entire length, and an output shaft 17 A tapepet 19 is detachably attached to the rear end 17a. Therefore, in this embodiment, in order to change the boost ratio, other than the reaction disk 16,
It is only necessary to change both the sleeve 18 and the tappet 19. Further, in this embodiment, the sleeve 18
Since this guides the rear end portion 17a (tapepet 19) of the output shaft 17, it is not necessary to finish the inner wall of the cylinder portion 14, making manufacturing easy.

FIG. 3 shows a third embodiment of the present invention, in which a sleeve 18' fitted into the cylinder part 14a of the spring retainer 14 has a front end 18a' as a large diameter part and a rear end 18b' as a large diameter part. The rear end portion 18b', which is formed as a small diameter portion and has a small diameter, is inserted into the hole 13a of the reaction plate 13.
A tappet 20 detachably attached to the front end 9b of the plunger 9 faces within the rear end 18b'. Therefore, in this embodiment, in order to change the boost ratio, it is only necessary to replace the reaction disk 16, the sleeve 18', and the tappets 19, 20. Also, the rear end 18 of the sleeve 18'
Since b' acts as a cylinder to guide the plunger 9, this method can be used when the reaction plate 13 is relatively thin and the plunger 9 cannot be guided sufficiently with this thickness alone. It's advantageous.

In the above embodiment, a case has been described in which the power piston 3 is composed of two members, the valve body 6 and the piston plate 7, but the power piston 3 may be composed of a single member made of synthetic resin as in the conventional case. . Also, reaction disk 1
6 is accommodated, and the rear end 17a of the output shaft 17
The case has been described in which the spring retainer 14 is used to form the cylinder part 14a into which the cylinder part 14a is slidably inserted. The biasing force of the return spring 15 may be directly received by the reaction plate 13 and applied to the power piston, that is, the reaction plate 13 may also serve as a spring retainer. Of course, the present invention is not limited to a pneumatic booster in which the front chamber 4 and the rear chamber 5 are in a vacuum-to-atmosphere relationship during boosting operation; It may also be a pneumatic booster that works like compressed air.

(Effects of the Invention) As described above, the present invention does not directly transmit force between the power piston and the reaction disk, but transmits force through the reaction plate whose outer periphery is in contact with the power piston over a large area. Since the power is transmitted, strong force does not act locally on the power piston, and the durability of the power piston itself can be improved. In particular, since the force of the return spring can be applied to the power piston through the reaction plate without directly abutting the power piston and the return spring, in addition to the above, the durability is further improved. You can improve your performance.

When boost operation starts, a fairly large force acts on the outer periphery of the power piston due to the pressure difference on both sides of the diaphragm, but in the present invention, the outer periphery of the reaction plate prevents the valve body from deforming. Even if it is made of synthetic resin with weak strength, it can withstand long-term use without having to be thick.

Furthermore, the power piston constituted a mechanism in which the boost ratio was determined by a separately provided reaction plate and a spring retainer having a cylinder portion in which the reaction disk and the rear end of the output shaft were accommodated. Therefore, the boost ratio can be easily and inexpensively changed without replacing the power piston.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a pneumatic booster according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view of essential parts showing a second embodiment of the present invention, and FIG. FIG. 4 is a cross-sectional view of a conventional pneumatic booster. 1... Main body, 2... Diaphragm, 3... Power piston, 4... Front chamber, 5... Rear chamber, 8... Input shaft, 9... Plunger, 13... Reaction plate, 13a... Hole, 14... Spring retainer (cylinder member) , 14a... cylinder section, 16... reaction disk, 17... output shaft.

Claims (1)

[Claims] 1 The interior of the main body is divided into two chambers, a front chamber and a rear chamber, by a diaphragm and a power piston attached to the diaphragm, and when the input shaft is actuated to generate a pressure difference between the two chambers, the The forward thrust generated in the power piston is transmitted to the output shaft through a reaction disk made of a pressurized deformable member such as an elastic body, and the reaction force from the output shaft is transmitted to the input shaft through the reaction disk. In a pneumatic booster configured to transmit power to a shaft, a reaction plate is disposed on the front surface of the power piston, the outer circumference of which comes into contact with a synthetic resin valve body that is the outer circumference of the power piston, and
A hole is formed in the reaction plate to guide the head of the plunger provided at the front end of the input shaft, and a spring retainer having a cylinder portion having a larger diameter than the guide hole is provided on the front surface of the reaction plate. A pneumatic booster characterized in that the reaction disk is disposed in the cylinder portion, and the rear end portion of the output shaft is fitted into the cylinder portion.