JPH0739719Y2 - Tandem type pneumatic booster - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a tandem type pneumatic booster provided in a brake system of a vehicle such as an automobile.

(Prior Art) In recent years, in many automobiles, the pressure difference between the engine suction negative pressure and the atmospheric pressure is used to increase the brake fluid pressure generated in the master cylinder so that a large braking force can be obtained with a small pedal effort. A pneumatic booster is installed. Some vehicles equipped with high-power engines and large vehicles are equipped with a tandem type pneumatic booster in order to obtain a greater boosting effect.

An example of such a tandem type pneumatic booster is shown in FIG. 2 and will be briefly described. This tandem type pneumatic booster 1
Has a housing 4 composed of a front shell 2 and a rear shell 3, and the inside of the housing 4 is divided into two chambers 6 and 7 by a center plate 5. The front chamber 6 is defined by a front power piston 9 having a front diaphragm 8 into a front constant pressure chamber 10 and a front variable pressure chamber 11, and the rear chamber 7 is defined by a rear power piston 13 having a rear diaphragm 12. It is divided into 14 and rear transformation room 15. Each of the constant pressure chambers 10 and 14 communicates with a negative pressure source (not shown) and is always in a negative pressure state.

Each power piston 9, 13 is fixed to a valve body 16, an output rod 17 is connected to the valve body 16, and a plunger 19 connected to an input rod 18 is slidably inserted. Further, the valve body 16 has an atmospheric valve 20 and a vacuum valve 21 built therein. This atmosphere valve 20
Is for connecting the variable pressure chambers 11 and 15 to the atmosphere when the input rod 18 moves forward relative to the valve body 16 (moves to the left in the figure).
The variable pressure chambers 11 and 15 and the constant pressure chambers 10 and 14 communicate with each other when the valve moves backward relative to the valve body 16 (moves to the right in the figure).

According to this configuration, when the brake pedal is depressed, the input rod 18 moves forward to open the atmosphere valve 20, the atmosphere is introduced into the front variable pressure chamber 15 and the rear variable pressure chamber 11, and the constant pressure chambers 10, 1
4 causes a pressure difference between the variable pressure chambers 11 and 15 and causes the power pistons 9 and 13 to move forward.
16 moves forward with a large force, and the thrust is transmitted to the output rod 17.

By the way, in recent years, the engine has become larger with the increase in output of the engine, and the space in the engine room is greatly restricted. Therefore, miniaturization of parts in the engine room is desired, and it is strongly demanded that the tandem type pneumatic booster be miniaturized without deteriorating the performance.

Therefore, as shown in FIG. 1, a communication passage 22 for communicating the front constant pressure chamber 10 and the rear constant pressure chamber 14 is provided so as to open to the outer periphery where the center plate 5 of the valve body 16 slides. Has its passage 22 at maximum forward
The length of the sliding portion must be set long so as not to be blocked by the center plate 5, and the length of the entire booster in the axial direction becomes longer accordingly, so that the front constant pressure chamber 10
Various proposals have been made to reduce the axial length of the entire booster by not providing the valve body 16 with a communication passage that connects the rear constant pressure chamber 14 and the rear constant pressure chamber 14.

For example, in the tandem type pneumatic booster disclosed in Japanese Utility Model Laid-Open No. 60-62363, a communication passage that connects the front constant pressure chamber and the rear constant pressure chamber is provided with a fixed wall provided in the housing so that the inside of the housing is divided into two. It has a heavy structure and is constituted by a gap between the fixed wall and the housing and a through hole provided on the front side of the fixed wall.

Further, in the tandem type pneumatic booster disclosed in Japanese Utility Model Publication No. 56-25965, a communication passage that connects the front constant pressure chamber and the rear constant pressure chamber is formed with a step portion on the outer periphery of the front shell. The outer peripheral bead portion of the front diaphragm is sandwiched between the central portion and the center plate, and a plurality of enlarged portions are provided in the circumferential direction of the step portion, and the enlarged portion is constituted.

(Problems to be Solved by the Invention) However, the conventional tandem type pneumatic boosters proposed in the above publications have the following problems.

In the tandem type pneumatic booster disclosed in Japanese Utility Model Laid-Open No. 62-62363, since the housing has a double structure with a fixed wall, the number of parts is large, the structure is complicated, and the assembling property is not good. There was a problem. Further, since the passage is provided between the housing and the fixed wall, if the pressure receiving area of the power piston is secured in order to maintain a predetermined performance, the dimension of the housing in the radial direction becomes larger by the amount of the communication passage. There was also.

Further, in Japanese Utility Model Publication No. 56-25965, although the above problem does not occur, in the enlarged portion of the front shell, the outer peripheral bead portion of the front diaphragm is supported only by the center shell, so that the outer peripheral bead portion sags during assembly. The airtightness may not be ensured. Therefore, it is necessary to confirm whether the airtightness is maintained after the assembling, and there is a problem that the productivity is reduced and the manufacturing cost is increased due to the increase of the inspection process.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a tandem type pneumatic booster that can be downsized without lowering productivity.

(Means for Solving the Problem) In the tandem type pneumatic booster of the present invention, a step portion is formed on the outer peripheral side of the housing, and the outer peripheral bead portion of the diaphragm on the front side is sandwiched between the step portion and the center plate. An enlarged portion that partially bulges outward is formed in the step portion, and a through hole is provided outside the outer peripheral bead portion in the center plate,
A ring member that forms a communication path that communicates the front constant pressure chamber and the rear constant pressure chamber with the enlarged portion and the through hole and that engages along the outer peripheral bead portion of the diaphragm to hold the outer peripheral bead portion. It is provided.

(Operation) With the above configuration, since the outer peripheral bead portion of the diaphragm on the front side is always held in a constant posture by the ring member provided along the outer peripheral bead portion, the front constant pressure chamber and the rear constant pressure chamber are separated from each other. Even if the outer peripheral bead portion is not in contact with the step portion in the enlarged portion forming the communication passage communicating with the outer peripheral bead, it is possible to prevent the outer peripheral bead portion from sagging during assembly.

(Embodiment) Next, an embodiment of the present invention will be described with reference to FIG.

In the tandem type pneumatic booster 23 of this embodiment, the front shell 24 and the rear shell 25 have a center plate 26 on the outer peripheral side.
It has a housing 27 that is joined by caulking via the inside of the housing 27.
It is divided into two rooms 28 and 29. The housing 27 is provided with a valve body 30 that is movable through the rear shell 25 and the center plate 26 in the axial direction thereof.
Each of the chambers is located on the outer periphery of the front side of the valve body 30 (left side in the figure)
The inner peripheral sides of the front power piston and the diaphragm are fixed to correspond to 28 and 29. That is, the front power piston 31 and the front diaphragm 32 are arranged in the front chamber 28, and the rear power piston 33 and the rear diaphragm 34 are arranged in the rear chamber 29. And the outer peripheral bead portion on the outer peripheral side of the front diaphragm 32.
32a is a stepped portion 3 formed on the outer peripheral side of the front shell 24.
The vertical plane of 5 and the center plate 26 are sandwiched and fixed. Further, the outer peripheral side of the rear diaphragm 34 is integrally fixed by caulking portions of the front shell 24 and the rear shell 25. With this configuration, the front chamber 28 in the housing 27 is defined by the front constant pressure chamber 36 and the front pressure changing chamber 37, and the rear chamber 29 is defined by the rear constant pressure chamber 38 and the rear pressure changing chamber 39.

Here, the structure of the communication passage 40, which is a main part of the present invention for communicating the front constant pressure chamber 36 and the rear constant pressure chamber 38, will be described. A predetermined number of enlarged portions 41 that bulge outward are provided in the step portion 35 in the circumferential direction, and a gap 42 is formed between the front shell 24 and the outer peripheral bead portion 32a of the front diaphragm 32 by the enlarged portions 41. Is occurring. Further, the outer peripheral bead portion 32 in the center plate 26 is made to correspond to the enlarged portion 41.
A through hole 43 is formed radially outward of a. The gap 42 and the through hole 43 form a communication passage 40 that connects the front constant pressure chamber 36 and the rear constant pressure chamber 38. A groove 44 is formed along the circumference of the outer bead portion 32a on the surface where the outer bead portion 32a abuts the vertical surface of the step portion 35, and a ring member 45 is fitted into the groove 44. ing. The ring member 45 is formed of a material having high rigidity such as metal or synthetic resin. The ring member 45 may be fixed by being fitted into the concave groove 44 as in the present embodiment, or may be integrally formed and fixed when the front diaphragm 32 is formed, and the outer peripheral bead portion It may be baked and fixed on 32a.

The front constant pressure chamber 36 is provided with a negative pressure introducing pipe 46 for connecting a negative pressure source such as an intake manifold (not shown) to the front constant pressure chamber 36, and the rear constant pressure chamber 38 is provided with a negative pressure via the communication passage 40. It will be connected to the pressure source.

A plunger 48 connected to one end of an input rod 47 is slidably fitted in the valve body 30. The other end of the input rod 47 is connected to a brake pedal (not shown).

A first valve seat 49 is formed inside the valve body 30, and a second valve seat 50 is formed at the rear end of the plunger 48. Further, inside the valve body 30, a valve body 51 that can be seated on and detached from the valve seats 49, 50 is arranged.

One of the valve bodies 30 opens to the front constant pressure chamber 36,
The other side is formed with a passage 52 that opens between the valve body 51 inside the valve body 36 and the first valve seat 49, and a rear constant pressure chamber that opens in the outer peripheral surface of the valve body 30 in the middle of the passage 52. A passage 53 communicating with 38 is connected. The valve body 30 has a passage 54, one of which opens to the front side of the first valve seat 49 and the other of which opens to the outer peripheral surface of the valve body 30, and one of which is the rear transformer chamber.
Passage 55 that opens to 39 and the other to front transformer room 37
And are formed.

Then, by separating (opening) the valve body 51 and the second valve seat 50, the atmosphere can be introduced into the respective variable pressure chambers 37, 39 through the passages 54, 55. The second valve seat 50 and the atmosphere valve 56 are formed. Further, by separating (opening) the valve body 51 and the first valve seat 49, the variable pressure chambers 37, 39 and the constant pressure chambers 36, 38 can communicate with each other via the passages 52, 53. The valve body 51 and the first valve seat 49 constitute a vacuum valve 57.

The input rod 47 is provided between the valve body 30 and the input rod 47.
A conical coil spring 58 for urging the valve body 30 is arranged rearward, and a return spring 59 for urging the valve body 30 rearward is arranged in the front constant pressure chamber 36.

The output rod 60 is connected to the front end of the valve body 30 so as to be slidable in the axial direction. The output rod 60 is connected between the valve body 30 and the output rod 60 to adjust the reaction force from the master cylinder. Reaction disc 61 is interposed.

Next, the operation of the tandem type pneumatic booster 23 having the above structure will be described.

First, the operation will be described. Before the engine is activated and the brake pedal is depressed, the negative pressure source and the front constant pressure chamber 36 are in communication, so the front constant pressure chamber 36 is in a negative pressure state. Since the chamber 38 communicates with each other via the communication passage 40 and the passages 52 and 53,
The rear constant pressure chamber 38 is in a negative pressure state. Also, each negative pressure chamber
The vacuum valves 57 of 39 and 39 are also opened as appropriate and are in a negative pressure state.

When the brake pedal is depressed and the input rod 47 moves forward, the plunger 48 moves forward from the standby state shown in FIG. 1, the second valve seat 50 separates from the valve element 51, and the atmosphere valve 56 opens. Atmosphere is introduced into the rear transformer room 39 and the front transformer room 37. When the atmosphere is introduced into each transformer room 37, 39,
A pressure difference is generated between the variable pressure chambers 37 and 39 and the constant pressure chambers 36 and 38, and the power pistons 31 and 33 move forward, and along with that, the valve body 30 and the output rod 60 move forward and double to the master cylinder (not shown). The applied force is output.

When the depression of the brake pedal is stopped, both the vacuum valve 57 and the atmosphere valve 56 are closed, so that the output of the boosted force to the master cylinder is maintained constant.

Then, when the depression of the brake pedal is released, the input rod 47 retracts with respect to the valve body 30 by the conical coil spring 58, and accordingly, the second valve seat 50 is seated on the valve body 51, and further the valve body 51. Is displaced rearward to separate from the first valve seat 49 to open the vacuum valve 57, and the respective variable pressure chambers 37 and 39 communicate with the constant pressure chambers 36 and 38 via the passages 52 and 53 so that negative pressure is generated therebetween. Then, due to the reaction force from the master cylinder, the valve body 30 is returned backward together with the input rod 47, and the original standby state is restored.

By the way, in the tandem type pneumatic booster 23 configured as described above, the front constant pressure chamber 36 and the rear constant pressure chamber 38 are communicated with each other by the communication passage 40 provided on the outer peripheral side of the front diaphragm 32. As described above, the sliding range between the valve body 30 and the center plate 26 is restricted and the axial length of the booster device is shortened in the axial direction without being lengthened in the axial direction.
In the present embodiment described above, the passage 53 that connects the front constant pressure chamber 36 and the rear constant pressure chamber 38 is provided on the outer peripheral surface of the valve body 30 so as to be opened, but this is a flow that does not limit the sliding range. Since it is formed with a road area, the passage 53 may not be provided.

Further, when the front diaphragm 32 is assembled in the housing 27, the outer peripheral bead portion 32a is always held in a constant annular posture by the ring member 45, so that the enlarged portion 41 contacts the vertical surface of the step portion 35. Even when not in use, the outer peripheral bead portion 32a is mounted without sagging and airtightness is secured. Therefore, the step of confirming that the front diaphragm 32 is securely attached is unnecessary.

(Effect of the Invention) As described in detail above, according to the present invention, the stepped portion formed on the outer peripheral side of the housing and the center plate sandwich the outer peripheral bead portion a of the diaphragm on the front side, and the enlarged portion 41 formed on the stepped portion. And a through hole formed in the center plate to form a communication passage that communicates the front constant pressure chamber and the rear constant pressure chamber, and a ring member that engages along the outer peripheral bead portion of the diaphragm to hold the outer peripheral bead portion. Since it is provided, when the front diaphragm is assembled in the housing, the outer peripheral bead portion is mounted by the ring member without sagging, and airtightness is secured. Therefore, the step of confirming that the front diaphragm is securely attached is not necessary, the productivity can be improved and the manufacturing cost can be reduced, and a good quality and inexpensive tandem type pneumatic booster can be provided.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a tandem type pneumatic booster of the present invention, and FIG. 2 is a vertical sectional view showing an example of a conventional tandem type pneumatic booster. 26 ... Center plate, 27 ... Housing 28, 29 ... Chamber 31 ... Front power piston 32 ... Front diaphragm 32a ... Peripheral bead 33 ... Rear power piston 34 ... Rear diaphragm, 35 ... Step 36 ... Front constant pressure chamber, 37 ... Front Transformer chamber 38 ... Rear constant pressure chamber, 39 ... Rear transformer chamber 40 ... Communication part, 41 ... Enlarged part 43 ... Through hole, 45 ... Ring member

Claims (1)

[Scope of utility model registration request] 1. A housing is divided into two chambers by a center plate, and each chamber is introduced by a power piston and a diaphragm into a front constant pressure chamber and a rear constant pressure chamber communicating with a negative pressure source, and negative pressure or atmosphere. It is divided into a front transformer room and a rear transformer room, and the atmosphere is introduced into each transformer room and the power piston is moved forward by the pressure difference generated between each constant pressure chamber and each transformer room to generate thrust that boosts the output rod. In the tandem type pneumatic booster device for transmitting, a step portion is formed on the outer peripheral side of the housing, and the outer peripheral bead portion of the diaphragm on the front side is sandwiched between the step portion and the center plate, and the step portion is partially outside. An enlarged portion is formed on the center plate, a through hole is provided outside the outer peripheral bead portion of the center plate, and the front constant pressure chamber and the rear constant pressure chamber communicate with each other by the enlarged portion and the through hole. A tandem-type pneumatic booster, characterized in that a ring member that forms a communication passage for holding the outer peripheral bead portion is provided along with the outer peripheral bead portion of the diaphragm.