JPH09309425A - Booster - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformly generate changeover timing of servo ratio in a booster after starting operation, by integrally fitting an annular member formed of rigid material to a peripheral part of a reaction disk opposed to a tip end face of a valve plunger to transmit reaction force of an output acting in an output shaft to an input shaft through a valve plunger. SOLUTION: A rear part of a stepped hole 1A in a valve body 1 is formed as a tubular part 1b extended toward a leftward side, to this tubular part 1b, a recessed hollow part 3a formed in a base part of an output shaft 3 is slidably fitted. In the recessed hollow part 3a of this output shaft 3, a rubber-made disk-shaped reaction disk 4 is stored, in its peripheral part total region, an annular member 5 having rigidity to consist of metal is baked, to be integrally fitted. In this way, changeover timing of servo ratio of a booster after starting operation can be uniformly generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a booster, and more particularly to improvement of a reaction disk in the booster.

[0002]

2. Description of the Related Art Conventionally, a booster having the following structure is known. That is, a roughly cylindrical valve body slidably provided in the shell, a valve plunger slidably fitted to the valve body and interlocking with the input shaft, and a base portion slidably mounted on the valve body. The reaction force of the output acting on the output shaft, which is interposed between the fitted output shaft, the base of the output shaft and the end surface of the valve body and faces the tip end surface of the valve plunger, is passed through the valve plunger. A reaction disc that transmits to the input shaft and a recess formed on the end face of the valve body that contacts the reaction disc are provided.In a non-operating state where the input shaft is not advanced, a gap is formed between the reaction disc and the tip face of the valve plunger. The booster thus formed is known (Japanese Patent Application Laid-Open No. 54-54154).
-111061, Japanese Patent Publication No. 2-38425). In the conventional booster described above, when the booster in which the input shaft is advanced is actuated, the reaction disc is compressed in the axial direction, so that the shaft portion of the reaction disc first faces the tip surface of the valve plunger. The reaction disk and the valve plunger come into contact with each other so that an output having a predetermined servo ratio is obtained from the output shaft. Further, after this, the outer peripheral portion of the reaction disk which is compressed in the axial direction is elastically deformed and relatively moves with respect to the valve body, and then is filled in the concave portion of the valve body. Then, after this time, the output increases with a larger servo ratio than before. As described above, in the conventional booster described above, the servo ratio after the start of operation can be changed in two steps.

[0003]

By the way, in the conventional booster described above, the entire reaction disk is manufactured from rubber. Therefore, when the outer peripheral portion of the reaction disc moves relative to the valve body due to elastic deformation of the outer peripheral portion of the reaction disc after the operation of the booster as described above, the outer peripheral portion of the reaction disc is made of rubber because the reaction disc is made of rubber. The frictional force between the sliding contact point of the valve body and the sliding contact point of the valve body was large. Even if the reaction discs are manufactured to have the same dimensions and the same shape, the frictional force between the outer peripheral portion of the reaction disc and the sliding contact portion of the valve body is not uniform after the reaction discs are installed in the respective boosters. . Therefore, the timing at which the outer periphery of the reaction disk is elastically deformed and filled in the recess of the valve body is slightly different depending on each booster. Therefore, conventionally, it has been pointed out that there is a drawback that the timing of switching the servo ratio after the start of operation varies depending on the individual boosters.

[0004]

In view of the above-mentioned circumstances, the present invention provides a generally cylindrical valve body slidably provided in a shell and an input shaft slidably fitted to the valve body. A valve plunger that interlocks with the valve shaft; an output shaft whose base is slidably fitted to the valve body; and a valve plunger that is interposed between the base of the output shaft and the end surface of the valve body and faces the tip end surface of the valve plunger. The reaction shaft that transmits the reaction force of the output acting on the output shaft to the input shaft through the valve plunger, and the recess formed on the end surface of the valve body that comes into contact with the reaction disc. In a booster in which a gap is formed between the reaction disc and the tip surface of the valve plunger in the operating state, an annular member made of a rigid body is provided on the outer peripheral portion of the reaction disc. One in which was fitted to the body.

[0005]

According to this structure, since the annular member made of a rigid body is fitted on the outer peripheral portion of the reaction disc, when the booster is operated and the outer peripheral portion of the reaction disc is elastically deformed. Causes the annular member to slide on the sliding contact portion of the valve body. At that time, the frictional force between the annular member made of a rigid body and the sliding contact portion of the valve body is small, and the deformation of the reaction disc is restricted because the outer peripheral portion of the reaction disc is integrated with the annular member. The reaction disk does not come into contact with the concave end surface of the valve body unless the predetermined output is obtained. Therefore, the switching timing of the servo ratio of the booster after the start of operation can be made uniform.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to illustrated embodiments. FIG. 1 shows an essential part in a shell of a negative pressure type brake booster. In FIG. 1, reference numeral 1 denotes a valve body slidably provided in a shell (not shown), and a shaft portion of the valve body 1 has an axial stepped hole 1A. In the small diameter hole 1a on the right side of the stepped hole 1A,
A valve plunger 2 which constitutes a valve mechanism is slidably fitted, and an input shaft (not shown) is connected to the right end of the valve plunger 2. The stepped portion of the stepped hole 1A in the valve body 1 is a tubular portion 1b that extends toward the left side, and the recessed portion 3a formed in the base portion of the output shaft 3 is slidable in the tubular portion 1b. Is fitted to. Recessed portion 3a of the output shaft 3
A rubber disk-shaped reaction disk 4 is housed therein, and the outer peripheral side of the end surface 4a on the right side of the reaction disk 4 is the cylindrical portion 1b of the valve body 1.
Is in contact with the end surface 1c of the. The left end face 4b of the reaction disc 4 is in contact with the bottom of the recess 3a of the output shaft 3. Thus, the reaction disc 4 is interposed between the bottom of the recessed portion 3a of the output shaft 3 and the end surface 1c of the tubular portion 1b. The shaft portion of the end surface 4a on the right side of the reaction disc 4 faces the tip surface 2a of the valve plunger 2. Further, the outer peripheral portion of the end surface 1c of the cylindrical portion 1b that is in contact with the reaction disc 4 is an annular recess 1d that is continuous in the circumferential direction. Therefore, in the non-actuated state of the brake booster shown in FIG. 1, the annular recess 1d and the end face 4a of the reaction disc 4 facing the recess 1d and the recess 3 of the output shaft 3 are formed.
An annular space is formed by the inner peripheral surface of a.
In the non-actuated state of the brake booster shown in FIG. 1, a required gap is formed between the right end face 4a of the reaction disc 4 and the front end face 2a of the valve plunger 2. . Further, the annular space formed by the annular recess 1d and the like is also maintained. The above-described configuration and the operation based on it are the same as those of the conventionally known negative pressure type brake booster. That is, when the brake pedal is depressed and the input shaft and the valve plunger 2 are advanced from the inoperative state in the drawing, the reaction disc 4 is compressed in the axial direction.
The reaction disk 4 compressed in the axial direction is
Since the shaft portion of the end surface 4a on the right side of the valve plunger 2 bulges toward the tip surface 2a of the valve plunger 2, the gap between them is eliminated and the shaft portion of the end surface 4a on the right side of the reaction disc 4 moves toward the valve plunger 2 Abutting on the front end surface 2a (Fig. 2). At that time, an output having a predetermined servo ratio can be obtained from the output shaft 3. At the same time, the reaction force of the output acting on the output shaft 3 is transmitted to the input shaft (not shown) via the reaction disc 4 and the valve plunger 2. Then, as shown in FIG. 4A, when the above-mentioned reaction disk 4 and the tip end surface 2a of the valve plunger 2 come into contact with each other, the output sharply rises, and the sharp output rise is generally called jumping. Has been done. After this jumping, assuming that the cross-sectional area of the tip end surface 2a of the valve plunger 2 is S1 and the cross-sectional area of the end surface of the tubular portion 1b in contact with the reaction disc 4 is S2, the servo ratio shown by (S1 + S2) / S1 Will increase the output. Further, when the reaction disc 4 is compressed, the outer peripheral portion of the reaction disc 4 is elastically deformed, and the recess 3a of the output shaft 3 is formed.
The inner peripheral surface and the concave portion 1d of the tubular portion 1b bulge toward the right side and are filled in the concave portion 1d (FIG. 3). Then, assuming that the cross-sectional area of the cylindrical portion 1b is S3, from the time point shown by B in FIG. Rises. Thus, by providing the annular recess 1d on the end surface 1c of the cylindrical portion 1b, the servo ratio after the start of the operation of the brake booster can be changed in two steps. The contents described above are basically conventionally known. Thus, in this embodiment, as shown in FIG. 1, an annular member 5 made of a metal having rigidity is baked on the entire outer peripheral portion of the reaction disc 4. The outer diameter of the annular member 5 is set to be the same as or slightly smaller than the outer diameter of the tubular portion 1b, and the concave portion 1d of the end face 1c is formed.
It is dimensioned to fit inside. Since the reaction disk 4 of the present embodiment integrally fits the annular member 5 on the outer peripheral portion in this way, as described above, the reaction disk 4 is axially compressed to include the annular member 5. When the outer peripheral portion slides toward the right side with respect to the inner peripheral surface of the concave portion 3a of the output shaft 3, the frictional force becomes small. Further, since the outer peripheral portion of the reaction disc 4 is integrally fitted with the annular member 5, the deformation of the reaction disc 4 is restricted so that the end face of the reaction disc 4 and the end face of the recessed portion 1d cannot be obtained unless a predetermined output is obtained. Does not touch. Therefore, it is possible to prevent the time point B of filling the inside of the concave portion 1d from being varied by bulging toward the right side with respect to the inner peripheral surface of the concave portion 3a of the output shaft 3 and the concave portion 1d of the tubular portion 1b. You can That is, the time point B at which the servo ratio is switched by each brake booster becomes uniform.
On the other hand, in the conventional reaction disc 4 shown in FIG. 7, since the whole is manufactured only from rubber, the reaction disc 4 may be affected by an error in manufacturing or surface roughness of the outer peripheral surface. The frictional force between the outer peripheral portion and the inner peripheral surface of the recessed portion 3a of the output shaft 3 was different, and accordingly, it was pointed out that the point B at which the servo ratio is switched varies. Is. (Second Embodiment) Next, FIG. 5 shows a second embodiment of the present invention. In the reaction disc 4 of the second embodiment, the rear end of the annular member 5 is formed with a radial portion 5a extending radially inward.
Even with the configuration of the second embodiment as described above,
The same operation and effect as the embodiment can be obtained. (Third Embodiment) FIG. 6 shows a third embodiment of the present invention. While the annular member 5 is fitted over the entire outer peripheral portion of the reaction disc 4 in both of the above-described embodiments, in the third embodiment, the rear side (right side) of the outer peripheral portion of the reaction disc 4 is mounted. Ring member 5 only at the end
Is burned. Even with the configuration of the third embodiment as described above, it is possible to obtain the same effect as that of the first embodiment described above. Although the metal annular member 5 is used in each of the above embodiments, the material of the annular member 5 may be a synthetic resin having rigidity. Further, in each of the above-described embodiments, the reaction disk 4 is housed in the recessed portion of the output shaft 3, but as disclosed in Japanese Patent Laid-Open No. 54-111061, the reaction is performed on the inner peripheral portion of the valve body. The present invention can also be applied to a reaction disk of a booster that is fitted with a disk.

[0007]

As described above, according to the present invention, it is possible to make uniform the switching timing of the servo ratio of the booster after the start of operation.

[Brief description of drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention.

FIG. 2 is a cross-sectional view of a main part of FIG. 1 in an operating state.

FIG. 3 is a sectional view of the main part of FIG. 1 in an operating state.

4 is a diagram showing a relationship between an input and an output of the brake booster shown in FIG.

FIG. 5 is a sectional view showing a second embodiment of the present invention.

FIG. 6 is a sectional view showing a third embodiment of the present invention.

FIG. 7 is a sectional view of a conventional brake booster.

[Explanation of symbols]

1 Valve body 1c End face 2 Valve plunger 2a Tip face 3 Output shaft 4 Reaction disc 5 Annular member

Claims (5)

[Claims] 1. A generally cylindrical valve body slidably provided in a shell, a valve plunger slidably fitted in the valve body and interlocking with an input shaft, and a base portion slidable on the valve body. The reaction force of the output acting on the output shaft is interposed between the movably fitted output shaft, the base of the output shaft and the end surface of the valve body, and faces the tip end surface of the valve plunger. A reaction disc that is transmitted to the input shaft via the valve and a recess formed on the end face of the valve body that contacts the reaction disc, and when the input shaft is not advanced, it is between the reaction disc and the tip surface of the valve plunger. A booster having a gap formed therein, wherein an annular member made of a rigid body is integrally fitted to the outer peripheral portion of the reaction disk. 2. A tubular portion is formed on the valve body, the end face is constituted by the end face of the tubular portion, and the recess is circumferentially formed on the outer peripheral side of the end face of the tubular portion. The reaction shaft is formed continuously, and a recess is formed at the base of the output shaft. The reaction disc is housed in the recess, and the recess is slidably fitted into the tubular portion of the valve body. The booster according to claim 1, wherein the booster is mounted, and further, the annular member is made of metal and has an outer diameter that can be fitted into a recess of the end surface of the tubular portion. 3. The booster according to claim 2, wherein the annular member is fitted so as to cover the entire outer peripheral portion of the reaction disc. 4. The rear end of the annular member is
4. The booster according to claim 3, further comprising a radial portion that extends radially inward. 5. The booster according to claim 2, wherein the annular member is fitted to an end portion of the outer peripheral portion of the reaction disc on the side of the tubular portion of the valve body.