JPH10100887A - Air pressure type booster - Google Patents

Abstract

PROBLEM TO BE SOLVED: To try to increase an output in secondary jamp-in by enlarging an effective diameter of a spring consisting of a reaction force adjusting mechanism in the air pressure type booster in which the reaction force adjustment mechanism is incorporated. SOLUTION: A reaction force adjusting mechanism 42 comprising a reaction force receiver 43 held in a specified set load by the use of a spring 45, is interposed between a plunger 25 in which a valve body 17 is incorporated, and a reaction disc 34 disposed in front of the valve body 17. In this case, the spring 45 is disposed in a hole 40 larger in diameter tan the sliding hole 41 of the reaction force receiver 43 so as to allow a necessary effective diameter to be secured, when an input transmitted from an input shaft 30 becomes greater than the set load of the spring 45 at the midway of a boosting action, let the spring 45 be contracted, and an output in a secondary jamp-in is produced, so that an input in the high output area is thereby lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic booster used for a vehicle brake system.

[0002]

2. Description of the Related Art As a pneumatic booster, the inside of a shell body is divided into a constant pressure chamber and a variable pressure chamber by a power piston having a diaphragm, and is connected to an input shaft in a valve body supported by the power piston. By disposing a valve mechanism including a plunger, and operating the valve mechanism in accordance with the sliding of the plunger, to generate a differential pressure between the constant pressure chamber and the variable pressure chamber, to propel the power piston, There is a type in which a thrust generated in a power piston is transmitted to an output shaft via a reaction disk, and a part of a reaction force from the output shaft is transmitted from the reaction disk to the input shaft via the plunger. .

[0003] In such a pneumatic booster, the relationship between the input and the output is usually such that, as shown in FIG. The output increases linearly with the increase, and the relationship continues up to the full load operating point B. The jump-in output A is a phenomenon caused by the presence of a gap between the reaction disk and the plunger when the actuator is not operated, and the larger this is, the higher the deceleration can be obtained.

In the above input / output characteristics, if the ratio between the input and the output, that is, the boosting ratio, is set small, a high input is required to obtain a high output as a matter of course. ), There is a possibility that a person with a weak pedaling force cannot output a sufficient output. On the other hand, if the boost ratio is set to a large value, a large output can be obtained even if the brake is lightly applied, so that sudden braking is performed carelessly, and it is quite troublesome to satisfy both requirements. The boost ratio is determined by the ratio of the contact area of the output shaft to the reaction disk and the contact area of the plunger. Therefore, when changing the boost ratio, a design change is required.

Therefore, for example, in the pneumatic booster described in Japanese Patent Application Laid-Open No. 8-85442, as shown in FIG.
Between the plunger 3 disposed in the valve body 1 so as to be interlocked with the input shaft 2 and the reaction disc 5 pressed by the valve body 1 by the output shaft 4, and between the reaction force receiver 6 and the spring receiver 7 A reaction force adjusting mechanism S that holds the spring 9 in a compressed state so as to generate a predetermined set load by using the bolt 8 is interposed. According to the pneumatic booster provided with such a reaction force adjusting mechanism S, as shown in FIG. 6, during the boosting action after the jump-in output A is generated, the input is the set load of the spring 9. C
Until the force reaches, the reaction force receiver 6 and the plunger 3 receive the reaction force as a unit, so that input / output characteristics basically unchanged from the conventional one can be obtained, but the input exceeds the set load C of the spring 9. Then, the secondary jump-in output D occurs due to the contraction of the spring 9 and the boosting ratio increases, so that the input (pedal force) can be reduced in a region where the output is large.

[0006]

In order to obtain a large secondary jump-in output D by utilizing the above-described bending of the spring 9, it is necessary to increase the amount of bending of the spring 9. In this case, the stress of the spring 9 when it is bent must be reduced, that is, the spring constant of the spring 9 must be reduced. On the other hand, in order to reduce the spring constant of the spring 9, it is necessary to increase the number of turns or to increase the effective diameter. However, if the number of turns is increased, the axial dimension of the valve body 1 and thus the booster becomes longer. Therefore, there is a problem in installation space for the vehicle, and it is therefore desirable to increase the effective diameter of the spring 9.

However, the pneumatic booster described in the above publication has a structure in which the spring 9 is housed in the sliding hole of the plunger 3 as it is, so there are certain restrictions on increasing the effective diameter thereof. There is a problem that it is difficult to obtain a desired secondary jump-in output D. In addition, in such a structure, the reaction force adjusting mechanism S often comes off toward the reaction disk 5 at the time of assembling, and there is a problem that the assembling property is poor.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems. It is an object of the present invention to increase the secondary jump-in output by enabling the use of a spring having a large effective diameter. To improve the assemblability.

[0009]

According to the present invention, in order to achieve the above object, a reaction force receiver receiving a reaction force from the reaction disk is provided between a plunger disposed in the valve body and the reaction disk by a spring. A reaction force adjusting mechanism held by a predetermined set load is interposed, and a spring of the reaction force adjusting mechanism has an effective diameter larger than a diameter of the reaction force receiver, and slides the reaction force receiver. The reaction force receiver is disposed in a large-diameter hole having a diameter larger than the diameter of the hole, and the reaction force receiver has a flange portion at a portion located in the large-diameter hole to restrict the reaction disk from coming off. It is characterized by having.

In the pneumatic booster configured as described above, the effective diameter of the spring can be set large without being restricted by the sliding hole for receiving the reaction force, so that a larger secondary jump-in output is obtained. be able to. In addition, since the reaction force receiving flange is located in the large-diameter hole in which the spring is disposed, the reaction force adjusting mechanism does not come off toward the reaction disk during assembly.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows the overall structure of a pneumatic booster according to the present invention, and FIG. 2 shows the main structure thereof. 1 and 2, reference numeral 10 denotes a shell body including a front shell 11 and a rear shell 12.
The inside of the shell body 10 is divided into a constant pressure chamber 15 and a variable pressure chamber 16 by a power piston 14 having a diaphragm 13. A large end portion 17a of a valve body 17 disposed on the axis of the shell body 10 is fitted and supported on the power piston 14. The valve body 17 is provided with the large end 17.
The portion following a is formed as a small-diameter cylindrical portion 17b, which extends rearward through the rear shell 12 in an airtight and slidable manner.

The valve body 17 has a cylindrical portion 17b.
A constant pressure passage 18 communicating the inside with the constant pressure chamber 15 is provided in the axial direction, and an air passage (atmospheric passage) 19 communicating the inside of the cylindrical portion 17b with the variable pressure chamber 16 is provided in the radial direction.
For example, an engine negative pressure is introduced into the constant pressure chamber 15 through an introduction pipe 20 connected to the front part of the front shell 11, while the cylindrical section 1 of the valve body 17 is introduced.
Atmosphere is introduced into 7b from the rear end opening through a silencer 21 and a filter 22.

A valve mechanism 23 for selectively opening a constant pressure passage (negative pressure passage) 18 and an atmosphere passage 19 to the variable pressure chamber 16 is provided in the valve body 17. The valve mechanism 23 is
The plunger 25 slidably received in the shaft hole 24 provided in the large end portion 17a of the valve body 17, the valve body 17
An elastically deformable valve body 27 having a base end fixed to the inner surface of the cylindrical portion 17b using a pressing member 26 (FIG. 2), an outer edge of the front end of the valve body 27 and an opening of the constant pressure passage 18 are included. Negative pressure valve 28 (FIG. 2) constituted by a valve seat portion formed on the inner periphery of valve body 17, an inner edge portion of the front end of valve body 27 and a valve seat portion formed on the rear end of plunger 25. Is provided. An input shaft 30 interlocked with a brake pedal (not shown) is connected to the rear end of the plunger 25, and the valve body 27 is normally operated by a valve spring 31 having one end engaged with the input shaft 30. Negative pressure valve 28
And the atmosphere valve 29 is closed. The input shaft 30 is normally urged toward the brake pedal by a return spring 32 having one end engaged with the pressing member 26. Further, the plunger 25 is provided with the valve body 17.
The relative movement range with respect to the valve body 17 is restricted by the stop key 33 inserted from the radial direction.

On the other hand, at the center of the front end of the large end 17a of the valve body 17, the base large end 35a of the output shaft 35 is operatively connected via a reaction disk 34 made of an elastic material such as rubber. The base large end 35a of the output shaft 35 has a cup shape,
Is housed in the cup of the base end 35a,
The central portion faces the shaft hole 24 of the valve body 17 described above. The constant-pressure chamber 15 is provided with a return spring 36 for returning the valve body 17 from the operating position to the non-operating position (the position shown in FIGS. 1 and 2). The return spring 36 is pressed against the valve body 17 by a spring receiver 37 (FIG. 2) that receives one end of the return spring 36. The front end of the output shaft 35 extends airtightly through the front shell 11 and extends forward.
For example, it is operatively connected to a master cylinder. A plurality of stud bolts 38 for mounting the booster to the vehicle body are provided on a rear surface of the rear shell 12, and a stud bolt 39 for mounting a master cylinder is provided on a front surface of the front shell 11.

Here, the shaft hole 24 of the valve body 17 is used.
Is formed as a stepped hole in which a large diameter hole 40 and a small diameter hole 41 are connected. The large diameter hole 40 is on the plunger 25 side (rear side), and the small diameter hole 41 is on the reaction disk 34 side (front side). ). In the shaft hole 24, the large-diameter hole 40 to the small-diameter hole 4
1, a reaction force adjusting mechanism 42 is provided. The reaction force adjusting mechanism 42 has a reaction force receiving member 43 having a tip end slidably fitted in the small-diameter hole 41 and a flange portion 43 a provided at an intermediate portion in the longitudinal direction thereof positioned in the large-diameter hole 40.
A hat-shaped spring receiver 44 disposed in the large-diameter hole 40 on the side of the plunger 25; and a spring interposed between the spring receiver 44 and the flange 43a of the reaction force receiver 43. 45, and a bolt 46 whose tip is screwed into the reaction force receiver 43 by passing the top of the spring receiver 44.

The spring 45 is held in a compressed state by adjusting the screwing amount of the bolt 46, and generates a predetermined set load. The spring 45 has an effective diameter sufficiently larger than the diameter of the small-diameter hole 42, that is, the diameter of the tip of the reaction force receiver 43, and its spring constant is smaller than that of the spring described in JP-A-8-85442. Is small.

The reaction force adjusting mechanism 42 is provided as a subassembly in which a reaction force receiver 43, a spring receiver 44, and a spring 45 are assembled by bolts 46, and the entire length thereof is ensured when the booster is not operated. , Is set to be smaller than the distance between the plunger 25 and the reaction disk 34. Therefore, in the non-operation state, the reaction force receiving 43
A predetermined gap 47 is ensured between the tip of the reaction disk 34 and the reaction disk 34. Also, the reaction force adjusting mechanism 42
A predetermined gap 48 is secured in the axial direction between the rear end of the reaction force receiver 43 and the front end of the spring receiver 44. On the other hand, the head of the bolt 46
The clearance enough to move a distance larger than 8 is ensured, so that the reaction force receiver 43 and the spring receiver 44 can relatively move within the size of the gap 48. The sub-assembly of the reaction force adjusting mechanism 42 is inserted into the valve body 17 from behind and assembled.
At the time of this assembly, the flange 43
a serves as a stopper to prevent the valve body 17 from coming off in the forward direction, thereby facilitating its assembly.

The pneumatic booster configured as above is
Stud bolts 3 planted on the rear surface of the rear shell 12
8, the input shaft 3 is attached to the vehicle body.
0 is connected to a brake pedal (not shown). And
When the brake pedal is depressed in this mounted state, the input shaft 30
The plunger 25 and the plunger 25 move integrally (forward) to the left in FIG. 1, and the atmosphere valve 29 opens to allow the atmosphere to flow into the valve body 17 through the silencer 21 and the filter 22,
This atmosphere is introduced into the transformation chamber 16 through an atmosphere passage 19. As a result, a pressure difference is generated between the constant pressure chamber 15 into which the negative pressure is introduced and the variable pressure chamber 16, and the front and rear power pistons 14 advance, and the thrust thereof is output via the valve body 17 to the output shaft. 35, and a boosting action is performed.

At the start of the boosting action, a predetermined set load of the spring 45 is applied to the reaction force receiver 43, so that the reaction force receiver 43 is moved in accordance with the advance of the plunger 25.
Moves forward, the gap 47 between the reaction force receiver 43 and the rear disk 34 is eliminated, and during this time, a predetermined jump-in output A
(FIG. 6) occurs. After the gap 47 is eliminated, a part of the reaction disk 34 is
And a part of the output reaction force is transmitted to the plunger 25 through the reaction force receiver 43, the spring 45 and the spring receiver 44.
And the input shaft 30. Therefore, input shaft 3
Until the input (pedal force) transmitted via the zero reaches the set load C (FIG. 6) of the spring 45, the output linearly increases in accordance with the input, and the input / output characteristics which are basically the same as those of the related art are obtained. can get. When the input exceeds the set load C of the spring 45, the spring 45 contracts and the gap 48 between the reaction force receiver 43 and the spring receiver 44 is eliminated. During this time, as shown in FIG. Jump-in output D
Occurs. In this case, since the gap 48 can be set large by making the effective diameter of the spring 45 sufficiently large, the above-mentioned secondary jump-in output D becomes larger than the conventional one (FIG. 6), and as a result, the output is large. The input (pedal force) can be greatly reduced in the area.

Here, when the pedaling force from the brake pedal is removed, the plunger 25 is retracted integrally with the input shaft 30 by the return spring 32, the negative pressure valve 28 is opened, and the negative pressure in the constant pressure chamber 15 is reduced from the constant pressure passage 18 to the atmosphere passage. Transformation chamber 16 after 19
And the differential pressure is eliminated. Thereafter, when the brake pedal is completely released, the power piston 14 and the valve body 1 are driven by the spring force of the return spring 36 in the constant-pressure chamber 15.
7 returns to the inoperative state shown in the figure.

In the present invention, as shown in FIG. 3, the small-diameter hole 42 in which the reaction force receiver 43 slides is formed in the shaft hole 2 of the valve body.
Alternatively, the valve body 17 itself may be replaced even if the diameter of the reaction force receiver 43 is changed (the boost ratio is changed). At least, it is possible to easily deal with the problem by replacing the spacer 50. In addition, the present invention can of course be applied to a so-called tandem-type pneumatic booster in which the inside of the shell body is divided into two chambers by a center shell, and the above-described constant pressure chamber and variable pressure chamber are arranged in each chamber. .

[0023]

According to the pneumatic booster according to the present invention,
By using a spring having a large effective diameter, the secondary jump-in output can be increased as much as possible, and the selection range of the boost ratio is widened. Further, the reaction force adjusting mechanism does not come off from the valve body at the time of assembling, so that the assembling property is improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the overall structure of a pneumatic booster as one embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a structure of a main part of the pneumatic booster.

FIG. 3 is a cross-sectional view showing a main structure of a pneumatic booster as another embodiment of the present invention.

FIG. 4 is a graph showing general input / output characteristics of a pneumatic booster.

FIG. 5 is a cross-sectional view showing a main structure of a conventional pneumatic booster provided with a reaction force adjusting mechanism.

FIG. 6 is a graph showing input / output characteristics of a conventional pneumatic booster provided with a reaction force adjusting mechanism.

[Explanation of symbols]

 10 Shell Body 13 Diaphragm 14 Power Piston 15 Constant Pressure Chamber 16 Variable Pressure Chamber 17 Valve Body 23 Valve Mechanism 25 Plunger 30 Input Shaft 34 Reaction Desk 35 Output Shaft 40 Large Diameter Hole 41 Small Diameter Hole 42 Reaction Force Adjusting Mechanism 43 Reaction Force 43a Flange 44 Spring receiver 45 Spring 46 Bolt

Claims (1)

[Claims] 1. A valve mechanism including a plunger connected to an input shaft in a valve body supported by the power piston, wherein the inside of the shell body is partitioned into a constant pressure chamber and a variable pressure chamber by a power piston having a diaphragm. By operating the valve mechanism in accordance with the sliding of the plunger, a differential pressure is generated between the constant pressure chamber and the variable pressure chamber to propel the power piston, and the thrust generated in the power piston is reacted. A pneumatic booster configured to transmit a reaction force from the output shaft via a disc to the input shaft via the plunger, and transmit a part of the reaction force from the output shaft to the input shaft via the plunger; A reaction force receiving a reaction force from the reaction disk with a predetermined set load between the disk and the reaction disk by a spring; A force adjusting mechanism is interposed, and a spring of the reaction force adjusting mechanism has an effective diameter larger than the diameter of the reaction force receiver, and a spring having a larger diameter than the sliding hole of the reaction force receiver. The pneumatic booster is characterized in that the reaction force receiver has a flange portion at a portion located in the large-diameter hole to restrict the reaction disk from coming off toward the reaction disk.