JP2606909B2 - Negative pressure booster - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vacuum booster used for a brake booster and the like, and more particularly to a vacuum booster provided with a reaction disk. .

(Related Art) Conventionally, in a brake booster using a negative pressure, a brake reaction force is transmitted to a brake pedal by a reaction force means in order to make a driver sense the magnitude of a control force during operation. .

As one of such reaction force means, Japanese Utility Model Laid-Open No. 57-70964
There has been known a reaction disk made of an elastic member as disclosed in Japanese Patent Application Laid-Open No. H10-209, etc.

The reaction disk is disposed in a recessed portion formed at the front end of the valve body of the brake booster. The rear end of the output shaft is in contact with the front surface of the reaction disk, and the front end of the valve plunger connected to the input shaft is opposed to the rear surface of the reaction disk.

When the vacuum booster is operated and the output shaft drives the brake master cylinder, the reaction force is transmitted to the reaction disk via the output shaft. For this reason, the reaction disc is elastically deformed in accordance with the magnitude of the reaction force and transmits the reaction force to the valve plunger by its elasticity, and the valve plunger reacts with the brake pedal via the input shaft connected thereto. It is designed to convey power. Thus, the driver can sense the magnitude of the control force.

(Problems to be Solved by the Invention) By the way, in a negative pressure booster provided with such a reaction disk, a reaction disk is required to transmit a reaction force from an output shaft to a valve plunger via the reaction disk. Has a structure in which the recessed portion in which is disposed must communicate with the valve plunger side.

However, with the structure in which the recessed portion communicates with the valve plunger side, the air enters the recessed portion from the valve plunger side and acts on the rear surface of the reaction disk when the brake booster is operated. . In this way, when the atmosphere acts on the rear surface of the reaction disk, the negative pressure of the constant pressure chamber acts on the front surface of the reaction disk, so that a pressure difference occurs between the front surface and the rear surface of the reaction disk, and the reaction disk Is applied with a forward force. However, at the very beginning of the operation, no braking force has yet been generated, and the braking reaction force is not transmitted to the reaction disk via the output shaft, so that the reaction disk is slightly moved forward by this force. For this reason, the rear surface of the reaction disk slightly rises from the bottom surface of the recessed portion, and the air passes through the minute gap between the rear surface of the reaction disk and the bottom surface of the recessed portion to enter the constant pressure chamber where the negative pressure is always maintained. I will be. As a result, there is a problem that the output of the negative pressure booster is lost.

In order to deal with this problem, the booster disclosed in the aforementioned publication presses the reaction disc toward the valve plunger by a spring means. Accordingly, even if atmospheric pressure is applied to the rear surface of the reaction disk at the very beginning of braking, the reaction disk is prevented from moving forward due to the urging force of the spring means.

By the way, in this booster, a spring means for pressing the reaction disk also serves to prevent the output shaft from coming off.

However, when the output shaft is also used to prevent the output shaft from falling off, the spring constant of the pressing portion that presses the reaction disk must be increased in order to ensure a sufficient retaining strength. Therefore, when the spring constant of the pressing portion is increased, the pressing load of the reaction disk varies greatly. For this reason, the jumping load required for the booster at the beginning of the operation greatly varies, and good jumping characteristics cannot be obtained.

Also, if the spring constant of the pressing portion is reduced in order to obtain good jumping characteristics, the output shaft cannot be sufficiently secured to prevent the output shaft from falling out, and the output shaft easily comes off from the recessed portion. Occurs.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a negative pressure capable of obtaining a good jumping characteristic and ensuring a sufficient retaining strength of an output shaft. The purpose is to provide a booster.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention forms a retaining portion for an output shaft on a retainer and, on both surfaces of the retainer, attaches a reaction disk to a valve plunger side. A pressing portion that elastically presses the pressing portion is formed.

(Operation) In the negative pressure booster according to the present invention having such a configuration, the retaining portion of the output shaft and the reaction disk pressing portion are separately formed. As a result, the strength of the retaining portion can be made relatively large, while the spring constant of the pressing portion can be made relatively small.

Therefore, the stopper prevents the output shaft from falling off.

In addition, the right surface of the reaction disk is pressed against the bottom of the recess by a relatively small elastic force. For this reason, airtightness between the right surface of the reaction disk and the bottom of the recessed portion is reliably ensured. Therefore, there is no output loss due to vacuum leakage at the very end of operation. In addition, since the spring constant of the reaction disk is relatively small, the jumping load in the initial stage of operation hardly varies. Therefore, the jumping characteristics of the negative pressure booster are stable and good.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing an embodiment in which a negative pressure booster according to the present invention is applied to a brake booster.

As shown in FIG. 1, the brake booster 1 includes a front shell 2 and a rear shell 3, and the front shell 2 and the rear shell 3 are connected by, for example, bayonet connection.

A valve body 4 is provided so as to penetrate the rear shell 3, and the valve body 4 is air-tightly and slidably supported by the rear shell 3 and a seal member 5. A power piston member 6 disposed in the space inside the shells 2 and 3 is connected to the valve body 4. A diaphragm 7 is provided between the shells 2 and 3 and the valve body 4 on the back of the power piston member 6. A power piston 8 is constituted by the power piston member 6 and the diaphragm 7, and the space inside the shells 2 and 3 is partitioned into a constant pressure chamber 9 and a variable pressure chamber 10 by the power piston 8.

The valve body 4 is formed with a concave fitting portion 11 that opens to the constant pressure chamber 9, and a bottom portion of the concave fitting portion 11 is formed with a projecting portion 4 a whose central portion projects toward the constant pressure chamber 9. The first hole 12 opening to the concave fitting portion 11 is provided substantially at the center of the projection 4a.
The second hole 13, the third hole 14, and the fourth hole 13 are successively formed rearward (to the right in the drawing) continuously from the first hole 12.
A hole 15, a fifth hole 16 and a sixth hole 17 opening to the atmosphere are respectively formed.

The valve body 4 is provided with an axial passage 18 communicating the negative pressure chamber 9 and the fifth hole 16.

The second hole 13 of the valve body 4 has a valve plunger 19.
And a rear end of the valve plunger 19 are slidably fitted in the third hole 14, respectively. An input shaft 20 linked to a brake pedal (not shown) is connected to the right end of the valve plunger 19. A radial hole 21 is formed in the valve body 4 so as to be orthogonal to the third hole 14, and a key member 22 penetrates through the hole 21 so that the key member 22 is axially opposed to the valve plunger 19. It is movably fitted. The key member 22 can move in the axial direction together with the valve plunger 19 by the width of the hole 21 (that is, the axial length). The key member 22 prevents the valve plunger 19 from coming out of the valve body 4.

Further, a passage 23 is formed in the valve body 4 so as to open to the variable pressure chamber 10 so as to be orthogonal to the third hole 14. This passage 23
Is connected to the fourth hole 15 through the passage 14a formed in the third hole 14.
Is in communication with

A control valve 24 is provided in the sixth hole 17 of the valve body 4. The control valve 24 is attached to the valve body 4 and is constantly urged in the direction of the valve plunger 19 by the resilient force of a spring 25 interposed between the control valve 24 and the input shaft 20.
A first valve seat 27 formed at the right end of the valve plunger 19;
A second valve seat 28 formed in the valve body 4. When the valve body 26 is seated on the first valve seat 27 and is separated from the second valve seat 28, the control valve 24
10 and the communication between the variable pressure chamber 10 and the atmosphere is cut off, the valve body 26 is separated from the first valve seat 27 and the second
When seated on the valve seat 28, the communication between the constant pressure chamber 9 and the variable pressure chamber 10 is cut off, and the switching control is performed so as to connect the variable pressure chamber 10 with the atmosphere.

A large-diameter portion on the right end of the output shaft 29 is provided in the concave portion 11 of the valve body 4, and a concave portion formed in the large-diameter portion on the right end is slidably fitted to the projecting portion 4 a of the valve body 4. Have been combined. A reaction disc 30 is housed in the concave portion of the right end large diameter portion between the projection 4a of the valve body 4 and the output shaft 29. In the first hole 12, a spacing member is provided between the reaction disc 30 and the left end of the valve plunger 19.
31 are interposed. By appropriately changing the cross-sectional area of the spacing member 31, the boost ratio can be changed even when the cross-sectional area of the valve plunger 19 is constant. This makes it possible to use the same valve plunger 19 for various negative pressure boosters.

A predetermined gap is set between the spacing member 31, the valve plunger 19, and the reaction disk 30.

The output shaft 29 is prevented from falling out of the valve body 4 by a retainer 33 urged rightward by a return spring 32 for returning the valve body 4 to the inoperative position.

As is clear from FIGS. 2 and 3, this retainer
33 includes an inner ring member 33a and an outer ring member 33b which are arranged concentrically.
3a and 33b are four arm members 33c arranged in a direction orthogonal to each other.
33c, ... connected. These arm members 33c, 33
are formed to have a relatively large width, and the strength thereof is secured to a predetermined size. In addition, these arm members 33c, 33
In the middle part of c,... are formed extending parts 33d, 33d,... extending in the circumferential direction substantially concentrically with the inner and outer ring members 33a, 33b. These extension portions 33d, 33d,... Are formed to have relatively small widths, and therefore have a small spring constant. The inner ring member 33a can pass through the small diameter portion of the output shaft 29 but cannot penetrate the large diameter portion.
have e. And, as is clear from FIG.
One set of extending portions 33d, 33d that are point-symmetrical to each other protrudes in one direction, and the other set protrudes in the opposite direction. That is, the extension portions 33d, 33d,.
Protrudes almost symmetrically on both sides.

The retainer 33 configured as described above is disposed so as to penetrate the small diameter portion of the output shaft 29, as shown in FIG.
It is constantly pressed against the valve body 4 by the return spring 32. In that case, the arm member 33d on the reaction disc 30 side,
33d presses the large diameter portion of the output shaft 29 toward the valve body 4. Therefore, the reaction disc 30 comes into pressure contact with the front end face of the projection 4a of the valve body 4. The pressing force at this time is relatively small because the spring constant of the arm members 33d, 33d is set small,
Therefore, the reaction disk 30 is pressed against by relatively weak elastic force. Thus, the extension parts 33d, 33d,
.. Are the pressing portions of the reaction disk 30.

The left end of the output shaft 29 is airtightly and slidably supported by a seal member 34 and protrudes out of the front shell 2. The left end of the output shaft 29 is linked to a piston of a master cylinder (not shown) attached to the front shell 2. Have been to be.

The valve body 4 and each power piston 8 connected thereto are normally held in the inoperative position shown by a return spring 32. In this non-operation state, the key member 22
By contacting the inner surface of the rear shell 3, the rightward movement of the valve plunger 19 is regulated, and the valve plunger 19 is held at the retreat limit position. And, when the input shaft 20 is not operated,
The key member 22 is at a position advanced with respect to the valve body 4, and at this time, the valve body 26 is connected to the first valve seat 27 and the second valve seat 27.
28, the transformation chamber 10 is isolated from both the atmosphere and the constant pressure chamber 9. Therefore, at the time of braking, as soon as the valve plunger 19 is actuated by the advancement of the input shaft 20, the valve body 26 and the first valve seat 27 are separated, and the variable pressure chamber 10 and the atmosphere come into immediate communication. I have.

The constant pressure chamber 9 communicates with, for example, an intake manifold of an engine (not shown) through a negative pressure introducing pipe 35 attached to the front shell 2. Therefore, a negative pressure is always introduced into the constant pressure chamber 9.

 Next, the operation of this embodiment will be described.

When the brake booster 1 is in the non-operating position shown in the drawing, the pressure in the variable pressure chamber 10 is slightly higher than the pressure in the constant pressure chamber 9 and is substantially balanced with the resilience of the return spring 32.

When the brake pedal is depressed for braking, the input shaft 20 moves forward toward the valve body 4. Input shaft 20
, The valve plunger 19 moves forward with respect to the key member 22 and the valve body 4. When the valve plunger 19 moves forward, the first valve seat 27 separates from the valve element 26 of the control valve 24. For this reason, air at atmospheric pressure is supplied to the sixth hole 17, the valve element 26 and the first valve seat 27.
, And flows into the variable pressure chamber 10 through the passages 14 a and 23 of the fourth hole 15 and the third hole 14. The air flowing into the variable pressure chamber 10 leaks into the first hole 12 through the gap between the valve body 4 and the valve plunger 19 in the second hole 13, and the leaked air acts on the rear end face of the reaction disk 30. Become like As a result, the reaction disk 30 is pressed forward and separates from the protruding portion 4a of the valve body 4, but the reaction disk 30 is
The reaction disc 30 does not separate from the protruding end face 4a of the valve body 4 because the reaction disc 30 is pressed rearward by the elastic force d. Therefore, the air leaking into the first hole 12 does not leak further toward the constant pressure chamber 9.
As a result, output loss caused by air leaking to the constant pressure chamber 9 side is prevented.

The power piston 8 is driven by the air flowing into the transformation chamber 10.
Operates, and the valve body 4 moves forward, so that the brake booster 1 generates an output via the output shaft 29 to operate the piston of the master cylinder. However, the braking effect does not yet occur due to various resistances in the brake circuit after the master cylinder. In the initial stage of such an operation, a predetermined gap is formed between the spacing member 31 and the reaction disc 30 and between the spacing member 31 and the valve plunger 19, so that the valve plunger 19 and the reaction disc 30 Are not engaged via the spacing member 31.

Once the aforementioned resistances are overcome, braking will begin. At this point, the gap between the reaction disc 30, the spacing member 31, and the valve plunger 19 is absorbed, so that the reaction disc 30 and the valve plunger 19 are engaged via the spacing member 31. Accordingly, the reaction force due to the braking is transmitted to the driver via the output shaft 29, the reaction disk 30, the spacing member 31, the valve plunger 19, and the input shaft 20. At this time, the output has already become considerably larger than the input, and a so-called jumping action is performed. In that case, there is almost no variation in the jumping load, so that the jumping characteristics are stable.

When the brake pedal is released to release the braking, the input shaft 20, the valve plunger 19, and the key member 22 are all moved rearward, that is, rightward, with respect to the valve body 4 until the key member 22 contacts the rear end wall of the hole 21. Move towards When the valve plunger 19 is retracted, the first valve seat 27 comes into contact with the valve body 26 to shut off the variable pressure chamber 10 from the atmosphere, and the valve body 26 moves to the second valve seat.
The variable pressure chamber 10 and the constant pressure chamber 9 communicate with each other at a distance from 28. As a result, the air in the variable pressure chamber 10 flows to the constant pressure chamber 9 and further flows to the intake manifold through the negative pressure introducing pipe 35. In this case, the valve plunger 19 is at the most retracted position with respect to the valve body 4, and the gap between the valve body 26 and the second valve seat 28 is maximized. Therefore, the air in the transformation chamber 10 flows quickly. Therefore, the valve body 4 and the power piston 8 are quickly retracted by the elastic force of the spring 31.

When the key member 22 abuts on the inner surface of the rear shell 3, the valve plunger 19 and the key member 22 do not retreat any further, but the valve body 4 continues to retreat further. When the second valve seat 28 comes into contact with the valve body 26, the air in the variable pressure chamber 10 does not flow out toward the constant pressure chamber 9, so that the power piston 8 does not retreat any more and is in the retreat limit position. Thus, the valve body 4 and the valve plunger 19 are in the initial inoperative position shown.

FIG. 4 is a front view of another embodiment of the retainer 33 according to the present invention. The components corresponding to the components of the above-described embodiment are denoted by the same reference numerals, and a detailed description thereof will be omitted.

As shown in FIG. 4, the retainer 33 is provided with a ring member 33b on the outer peripheral edge thereof.
Are formed at equal intervals in the circumferential direction. A pair of extending portions 33g, 33g are formed between these projecting portions 33f, and one of the pair of extending portions 33g, 33g projects in one direction and the other projects in the opposite direction. I have. In the retainer 33, the protruding portion 33f serves as a retaining portion for the output shaft 29, and the extending portion 33g serves as a pressing portion for the reaction disk 30.

FIG. 5 shows still another embodiment of the retainer 33. In this retainer 33, on the outer peripheral edge, the tip of a projection 33f similar to the projection in FIG. Are formed with a pair of extending portions 33d, 33d extending in the circumferential direction. One of the pair of extending portions 33d projects in one direction and the other projects in the opposite direction. And the protruding portion 33f is a retaining portion of the output shaft 29,
Further, the extending portion 33d is a pressing portion of the reaction disk 30.

FIG. 6 shows another embodiment of the retainer 33. The retainer 33 includes inner and outer ring members 33a and 33b and four arm members 33c and 33c as shown in FIG. ,…
It has. Extensions 33g, 33g,... Extending radially inward from the ring member 33b are formed between the arm members 33c. One set of the extension portions 33g facing each other projects in one direction, and the other set projects in the opposite direction. Then, the arm member 33c is connected to the output shaft 29.
The extension 33g serves as a pressing portion of the reaction disc 30.

In the retainer 33 of the negative pressure booster of the present invention configured as described above, the retaining portion of the output shaft 29 and the pressing portion of the reaction disk 30 are formed separately, so that the retaining portion is compared. The target strength can be increased, and the pressing portion can have a relatively small spring constant. As a result, not only can the output shaft 29 be securely prevented from coming off, but also the output loss at the beginning of operation can be prevented without impairing the jumping characteristics of the vacuum booster 1.

Further, since the pressing portion of the reaction disk 30 is formed so as to protrude from both sides of the retainer 33, there is no need to consider the mounting direction of the retainer 33 when assembling the retainer 33. Therefore, erroneous assembling of the retainer 33 does not occur, and not only is the assemblability improved, but also the retainer 33 can reliably exert the pressing function of the reaction disk 30.

The present invention is not limited to the above-described embodiment, and various design changes are possible.

For example, in any of the above embodiments, the pressing portion is
Although the same number is provided on both sides of the sheet, the number of pressing portions may be different from each other on both sides. In this way, the directionality is impaired, but two different types of jumping loads can be set.

Further, in the above-described embodiment, the retainer 33 is engaged with the valve body 4 by the return spring 32, but another engaging means may be used.

Further, in the above-described embodiment, the spacing member 31 is provided between the reaction disc 30 and the valve plunger 19 as a negative pressure booster.
Although the description has been made using the negative pressure booster 1 provided with the above, the present invention can also be applied to such a negative pressure booster that does not use the spacing member 31. Similarly, when the valve body 26 is not activated,
And the second valve seat 28 are separated from each other so that the variable pressure chamber 10 communicates with the atmosphere.

Further, in the above-described embodiment, the valve body 4 and the power piston member 6 are formed separately, but the invention can also be applied to a negative pressure booster in which these are integrally formed.

Furthermore, the above-described embodiment describes a case where the negative pressure booster of the present invention is applied to a brake booster.
The present invention can be applied to other boosters such as a clutch booster.

(Effects of the Invention) As is clear from the above description, the negative pressure booster according to the present invention is configured such that the retainer for retaining the output shaft is provided with the pressing portion of the action disk separately from the retaining portion. As a result, the strength of the retaining portion can be increased, and the spring constant of the pressing portion can be reduced. Therefore, not only can the output shaft be reliably prevented from coming off, but also there is almost no variation in the jumping load, so that an output loss at the beginning of operation can be prevented without impairing the jumping characteristics of the negative pressure booster. Become like

Further, if the pressing portions are provided on both sides of the retainer in substantially the same manner, erroneous mounting of the retainer can be prevented, so that the assembling property is improved, and the pressing portions are provided differently on both surfaces of the retainer. For example, two types of jumping characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment in which a negative pressure booster according to the present invention is applied to a brake booster, FIG. 2 is a front view of a retainer used in the booster, and FIG. 2 are sectional views taken along the line III-III, and FIGS. 4 to 6 are front views of other embodiments of the retainer, respectively. 1 ... Brake booster (negative pressure booster), 2 ... Front shell, 3 ... Rear shell, 4 ... Valve body,
9 ... constant pressure chamber, 10 ... variable pressure chamber, 19 ... valve plunger, 20
... input shaft, 24 ... control valve, 29 ... output shaft, 30 ... reaction disc, 33 ... retainer, 33c ... arm member (retaining part), 33d ... extension part (pressing part), 33f: Projecting part (retaining part), 33g ... Extension part (pressing part)

Claims (1)

(57) [Claims] 1. A valve body which is disposed so as to be able to advance and retreat in a space formed by a front shell and a rear shell, penetrates the rear shell in an airtight and slidable manner, and is connected to the valve body. A power piston that divides the space into a constant-pressure chamber into which a negative pressure is introduced and a variable-pressure chamber into which air at the time of operation is introduced, and a valve plunger slidably disposed on the valve body; An input shaft connected to the valve plunger and disposed in the valve body so as to be movable forward and backward; and an input shaft provided in the valve body and operated by the valve plunger to selectively change the variable pressure chamber to the atmosphere or the constant pressure chamber. A control valve for switching control to communicate with a reaction disk, and a reaction disk disposed in a concave fitting portion formed at a front end portion of the valve body facing the constant pressure chamber, An output shaft having an end fitted into the concave fitting portion and a front end penetrating through the front shell and protruding to the outside; and a pull-out preventing a rear end of the output shaft from falling out of the concave fitting portion. A negative pressure booster provided with a disc-shaped retainer having a stopper formed thereon.Further, on both surfaces of the retainer, a pressing portion for elastically pressing the reaction disc toward the valve body side is provided. A negative pressure booster characterized by being formed.