JPH0858565A - Air pressure type booster - Google Patents

Abstract

PURPOSE: To simplify the circumference of a housing so as to improve fitting property to a vehicle, and dispense with special sensors and control devices so as to simplify the construction and decrease the cost. CONSTITUTION: A plunger 14 capable of being interlocked with an input shaft 16 through a guide member 15 is arranged in a valve body 9 extended from a power piston 5 to the rear of a housing 1, and when movement of the valve body 9 is small, valve mechanisms 23, 24, 25 are interlocked with movement of the plunger 14 so as to introduce the atmosphere into a working pressure chamber 7 through an atmospheric passage 20, meanwhile, an opening/closing valve 36 connected to a high pressure air generating source 34 is provided on a casing 32 surrounding the valve body 9. Consequently when the valve body 9 is moved exceeding a prescribed value, the poppet 39 of the opening/ closing valve 36 is operated by the step difference part 41 on the outer circumference of the valve body 9, high pressure air is introduced into the working pressure chamber 7, and thrust is generated on the power piston 5 in two stages according to pressure difference against a negative pressure chamber 6.

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 in a brake system of a vehicle or the like.

[0002]

2. Description of the Related Art Generally, a pneumatic booster divides a housing into a negative pressure chamber and a working pressure chamber by a power piston having a diaphragm, and the power piston has a negative pressure passage and an atmosphere passage. A valve body is installed, and a valve mechanism for switching between the negative pressure passage and the atmosphere passage for the working pressure chamber is provided in the valve body. Is introduced to generate a thrust force boosted by the power piston due to the pressure difference between the negative pressure chamber and the working pressure chamber. However, according to such a general pneumatic booster, the thrust generated in the power piston depends on the difference between the negative pressure in the negative pressure chamber and the atmospheric pressure in the working pressure chamber, so that a large thrust force should be obtained. In that case, the power piston must be formed in a large size, or the negative pressure chamber and the working pressure chamber must be configured as a tandem type, which inevitably results in an increase in size.

Therefore, recently, the development of a pneumatic booster in which high pressure air is introduced into the working pressure chamber to further increase the thrust has been advanced. For example, Japanese Utility Model Laid-Open No. 5-32209 discloses a working pressure chamber. A high pressure air source is connected via an electromagnetic on-off valve, and the electromagnetic on-off valve is opened based on signals from a brake sensor, vehicle speed sensor, load sensor, etc., and high pressure air is introduced into the operating pressure chamber to operate with the negative pressure chamber. A pressurized pneumatic booster adapted to increase the pressure differential with the pressure chamber is described (see paragraphs 22 and 23 of the specification).

[0004]

However, according to the pressurizing type pneumatic booster disclosed in the above publication, the electromagnetic on-off valve for communicating and shutting off high pressure air is provided independently of the housing. There has been a problem that the area around the housing becomes complicated and installation on the vehicle becomes troublesome. Further, since the on-off valve is controlled based on signals from various sensors, a special control circuit is required, which not only complicates the entire structure of the device but also causes a problem of high cost.

The present invention has been made in view of the above-mentioned problems of the prior art, and its problem is to improve the mountability to a vehicle by simplifying the circumference of the housing.
It is an object of the present invention to provide a pressure-type pneumatic booster that simplifies the structure and reduces the cost by eliminating the need for special sensors and control circuits.

[0006]

In order to solve the above problems, the present invention divides the inside of a housing into a negative pressure chamber and a working pressure chamber by a power piston having a diaphragm, and the power piston has a negative pressure passage, A valve body having an atmosphere passage and a high-pressure air passage is attached, and the valve body is slidably inserted into the housing and extended to the rear of the valve body. On the other hand, a first valve mechanism for switching between the negative pressure passage and the atmosphere passage is provided, and the atmosphere passage is provided around the valve body with respect to the working pressure chamber according to the movement amount of the valve body with respect to the housing. The second valve mechanism for switching between the high pressure air passage and the high pressure air passage is integrally arranged.

[0007]

In the pneumatic booster configured as described above, the first valve mechanism for switching the negative pressure passage and the atmosphere passage to the working pressure chamber, and the atmosphere passage and the high pressure air to the working pressure chamber. Since the second valve mechanism for switching between the passage and the passage is integrally provided inside and outside the valve body, the area around the housing becomes simple.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 and 2 show a first embodiment of the present invention. In both figures, reference numeral 1 denotes a housing composed of a front shell 2 and a rear shell 3, the interior of which is divided into a negative pressure chamber 6 and an operating pressure chamber 7 by a power piston 5 having a diaphragm 4. Negative pressure is introduced into the negative pressure chamber 6 from a negative pressure source (not shown) such as an intake manifold of the engine through a negative pressure introducing port 8 provided in the front shell 2. A valve body 9 is arranged on the axis of the housing 1, and the valve body 9
While connecting the large-diameter main body 10 to the diaphragm 4 and the power piston 5, the small-diameter hollow shaft portion 11 following the main body 10 is inserted into the rear shell 3 and extended to the rear of the housing 1. There is. In addition, this hollow shaft portion 11
A seal member 12 seals between the rear shell 3 and the rear shell 3.

The body portion 10 of the valve body 9 is provided with a stepped shaft hole 13, and the tip of a long plunger 14 arranged on the axis of the valve body 9 is provided in the small diameter portion of the shaft hole 13. The part is slidably fitted. The plunger 14 is slidably inserted into an annular guide member 15 fitted in the hollow shaft portion 11 of the valve body 9 to allow the hollow shaft portion 1 to move.
1 is extended toward the rear end opening 11a side, and an input shaft 16 that is interlocked with a brake pedal (not shown) is operatively connected thereto. The guide member 15 includes the rear end opening 1 of the hollow shaft portion 11.
It is inserted from 1a until it sits on a step 11b in the hollow shaft portion 11, and is prevented from coming off from the outer periphery of the hollow shaft portion 11 by a stopper piece 17 driven therein.

An air chamber 18 is defined between the guide member 15 and the rear surface of the main body 10 of the valve body 9, and the air chamber 18 and the negative pressure chamber 6 are communicated with each other at an eccentric position of the main body 10. The negative pressure passage 19 is provided at the eccentric position of the guide member 15 with the air chamber 18 and the rear end opening 11 of the hollow shaft portion 11.
Atmosphere passages 20 that communicate with a are respectively formed. Further, the main body portion 10 and the hollow shaft portion 11 of the valve body 9 are
A radial communication passage 21 that communicates the air chamber 18 with the working pressure chamber 7 is formed in the connection portion with. A stopper piece 22 having one end fitted in the annular groove 14 a of the plunger 14 is loosely inserted in the communication passage 21. The stopper piece 22 can slightly move in the axial direction of the valve body 9 in the communication passage 21, and the plunger 14 can also slide in the axial direction within the movement range of the stopper piece 22.

In the air chamber 18, an annular valve seat portion 23 including the opening edge of the negative pressure passage 19 is formed on the inner peripheral surface of the valve body 9, and the plunger 14 also has an annular valve seat portion. 24 are formed. Further, the front end side of the guide member 15 is a small diameter portion 15a slightly smaller than the inner diameter of the hollow shaft portion 11 of the valve body 9 as shown in FIG. 2, and the valve member 25 slides on the small diameter portion 15a. It is installed freely. The valve member 25 is provided with an inner flange-shaped valve body portion 25a at the tip thereof.
Can be seated on and off the valve seat portions 23, 24. A valve spring 26 is arranged inside the valve member 25,
The valve spring 26 has a valve body 25 of the valve member 25 at one end thereof.
In addition to being engaged with the inside of a, the other end is engaged with the front end of the guide member 15 via the check valve 27. Due to the presence of the valve spring 26, the valve member 25 is kept seated on the valve seat portions 23 and 24 when the booster is inoperative, and the check valve 27 is in contact with the front end of the guide member 15. The atmosphere passage 19 is kept closed. The valve member 25, the valve seat portions 23 and 24, the valve spring 26, and the like constitute a first valve mechanism that switches between the negative pressure passage 19 and the atmosphere passage 20 with respect to the working pressure chamber 8, and the right side of the plunger 14 or The negative pressure passage 19 and the atmosphere passage 20 are selectively opened to the working pressure chamber 7 via the communication passage 21 in accordance with the movement to the left.

A large diameter portion of the output shaft 29 is accommodated in a large diameter portion of the shaft hole 13 of the valve body 9 via a reaction disk 28 made of rubber. The front end of the output shaft 29 extends through the front shell 2 to the front of the housing 1, and a master cylinder (not shown) is operatively connected thereto. Further, the entire valve body 9 is provided with a return spring 30 arranged in the negative pressure chamber 6 of the housing 1.
Is urged toward the input shaft 16 side.

On the other hand, of the hollow shaft portion 11 of the valve body 9,
A through hole 31 penetrating the inside and the outside of the housing 1 is formed in a portion extending to the outside of the housing 1. The hollow shaft portion 11 including the through hole 31 is surrounded by the hollow shaft portion 11 and the rear shell 3. A casing 33 that forms a closed pressure chamber 32 is disposed between them. In this casing 33,
An on-off valve 36 connected to a high-pressure air source 34 described later via a pipe 35 is mounted. The on-off valve 36 is a pipe member 37 screwed into a stepped hole provided in the casing 33, and a poppet 3 which is seated on and off a valve seat portion 38 formed in the stepped hole.
9 and one end of the poppet 3 by abutting the end face of the pipe member 37.
9 and a valve spring 40 for urging the valve seat portion 38 in the direction of sitting on the valve seat portion 38.

The poppet 39 has a hollow shaft portion 11 at its shaft portion.
It extends so that it can contact the outer peripheral surface of the. Then, on the outer peripheral surface of the hollow shaft portion 11, there is formed a step portion 41 having a conical surface shape which connects the small diameter portion on the front side and the large diameter portion on the rear side. In the inactive state of the booster, the hollow shaft portion 11 is positioned such that the small-diameter portion of the front side of the step portion 41 is positioned with respect to the poppet 39. In this state, the poppet 39 is seated on the valve seat portion 38 and high pressure is applied. The inflow of high pressure air from the air source 34 into the pressure chamber 32 is blocked. On the other hand, when the valve body 9 moves (forwards) beyond the predetermined distance L (FIG. 2) with respect to the housing 1 from this state, the poppet 39 moves to the step portion 41.
Riding over the large diameter portion of the hollow shaft portion 11 and moving upward against the biasing force of the valve spring 40, the high pressure air source 3
High-pressure air is supplied from 4 into the pressure chamber 32.

Each of the guide member 15 and the plunger 14 is formed with holes 42 and 43 for communicating the through hole 31 with the air chamber 18 in the valve member 25. The through-hole 31 and the holes 42, 43 form a high-pressure air passage, and under the condition that the opening / closing valve 36 is opened and high-pressure air is introduced into the pressure chamber 32, the air chamber 18 passes through the high-pressure air passage.
If high pressure air is introduced into the valve 14 and the valve seat portion 24 of the plunger 14 is separated from the valve member 25 at this time, the high pressure air is supplied to the working pressure chamber 7 through the communication passage 21. Further, the check valve 27, the opening / closing valve 36 on the casing 33, the step portion 41 on the outer peripheral surface of the hollow shaft portion 11 and the like are released from the working pressure chamber 7 according to the moving amount of the valve body with respect to the housing 1. Passage 20 and high pressure air passages 31, 4
A second valve mechanism for switching between 2 and 43 is configured.

The high pressure air source 34 is the compressor 45.
And two check valves 46 provided in the middle of the pipe 35.
And an air dryer 47. Also, piping 3
An air tank 48 is interposed in the middle of 5, and the high-pressure air generated by the high-pressure air source 34 is temporarily stored in the air tank 48 and then supplied to the opening / closing valve 36 side. The same negative pressure source as that for the negative pressure chamber 6 of the housing 1 is connected to a portion of the pipe 35 located between the two check valves 46 via a negative pressure pipe 49.
An electromagnetic opening / closing valve 50 is interposed in this.

The operation of the pneumatic booster configured as described above will be described below. In the inoperative state shown in FIGS. 1 and 2, not only the negative pressure chamber 6 but also the operating pressure chamber 7 is in a negative pressure state. When the brake pedal is depressed from this state, the input shaft 16 moves (forward). Then, the plunger 14 moves to the left and the valve seat portion 24 of the plunger 14 moves to the valve member 2
5 is separated from the valve body portion 25a. Then, the guide member 1
Due to the pressure difference before and after 5, the check valve 27 opens and the air passage 2
Atmospheric air flows into the air chamber 18 from 0, and this atmospheric air passes through the communication passage 2
1 is introduced into the working pressure chamber 7. As a result, a differential pressure is generated between the negative pressure chamber 6 into which the engine negative pressure is introduced and the working pressure chamber 7, and a forward thrust force is generated in the power piston 5. This thrust is transmitted to the master cylinder (not shown) via the valve body 9, the reaction disk 28 in the valve body 9, and the output shaft 29, and the boosting action is started. During the boosting action, the reaction disk 28 elastically deforms, and a part of the reaction disk 28 is deformed.
The reaction force is transmitted to the input shaft 16 via the plunger 14 by protruding to the small diameter portion of the shaft hole 13.

When the brake pedal is further depressed and the valve body 9 moves forward with respect to the housing 1 beyond a predetermined distance L (FIG. 2), the poppet 39 of the opening / closing valve 36 is biased by the valve spring 40. On the contrary, the high pressure air is supplied from the high pressure air source 34 into the pressure chamber 32 while being separated from the valve seat portion 38. The high pressure air in the pressure chamber 32 flows into the air chamber 18 through the through hole 32 of the small diameter shaft portion of the valve body 9 which is a high pressure air passage, the hole 42 of the guide member 15 and the hole 43 of the plunger 14, and the high pressure air Check valve 2 by air
7 is pressed against the end surface of the guide member 15 so that the air passage 20
Close. On the other hand, this high pressure air flows into the working pressure chamber 7 through the communication passage 20 because the valve seat portion 24 of the plunger 14 is separated from the valve member 25, and as a result, the negative pressure chamber 6 and the working pressure chamber 7 And a larger differential pressure is generated between the two, and a large forward thrust is generated in the power piston 5.

Therefore, now, the moving distance (the amount of forward movement) of the valve body 9 until the poppet 39 of the opening / closing valve 36 is opened.
If L is set to the amount of advance of the valve body during high deceleration braking, a large braking force can be obtained during high deceleration braking. According to the present embodiment, the advance amount L is the hollow shaft portion 11
This can be easily changed by changing the position of the step portion 41 provided on the outer peripheral surface, and the design change can be easily dealt with. Further, since the opening / closing valve 40 has a simple structure including the poppet 39, it is advantageous in terms of cost.

When the pedaling force is removed from the brake pedal, the plunger 14 is pushed by the reaction disc 28 and moves to the right, and accordingly, the valve seat portion 24 of the plunger 14 is moved to the valve body portion 25a of the valve member 25. It abuts and moves the valve member 25 to the right. As a result, the introduction of the atmosphere or high-pressure air into the working pressure chamber 7 is cut off, while the negative pressure chamber 6
The negative pressure inside is introduced into the working pressure chamber 7 through the negative pressure passage 20 and the communication passage 21, and the above-mentioned differential pressure becomes small and the thrust is reduced. When the brake pedal is completely released, the valve body 9 is returned to its original position by the pressing force of the return spring 30, and the valve member 25 is seated on the two valve seat portions 23 and 24 again.

3 and 4 show a second embodiment of the present invention. Since the overall structure of the second embodiment is the same as that of the first embodiment, the same parts are designated by the same reference numerals and the description thereof will be omitted. The feature of the second embodiment is that the second valve mechanism in the first embodiment, that is, the on-off valve 36 on the casing 33,
By removing the step portion 41 and the like on the outer peripheral surface of the hollow shaft portion 11, a sub-rear shell 52 that forms a closed accumulator chamber 51 between the rear shell 3 and the valve body 9 is integrated in the back portion of the housing 1, and the rear rear shell 52 is End tubular portion 52
O ring 5 is provided between a and the small diameter shaft portion 11 of the valve body 9.
3, an annular seal member 54 is interposed, and a high pressure air inlet 55 is provided in a part of the sub rear shell 52.
The high pressure generation source 34 is connected to the inlet 55 through a pipe 35.
It is at the point where they were connected.

In the second embodiment, the seal member 5 is used.
4 is positionally fixed to the sub rear shell 52 by a stopper plate 56 that is integral with the sub rear shell 52,
The valve body 9 is slidable inside the seal member 54. Further, the through hole 32 (atmosphere passage) provided in the hollow shaft portion 11 of the valve body 9 is closed by the seal member 54 when the booster is not in operation. On the other hand, from this state, the valve body 9
Is advanced beyond a predetermined distance L (FIG. 4), the through hole 32 of the valve body 9 is disengaged from the seal member 54, whereby the high pressure air in the pressure accumulating chamber 51 passes from the through hole 32 to the hole 42 of the guide member 15. And it is introduced into the air chamber 18 in the valve member 25 through the hole 43 of the plunger 14.

In the second embodiment, while the amount of depression of the brake pedal is small, the valve seat portion 24 of the plunger 14 is operated by the movement of the plunger 14 interlocking with the input shaft 16 as in the first embodiment. The air is introduced from the atmosphere passage 20 into the working pressure chamber 7 away from the valve body 25a of the member 25, and a predetermined thrust is generated in the power piston 5. on the other hand,
When the brake pedal is further depressed and the valve body 9 advances beyond the predetermined distance L (FIG. 4) with respect to the housing 1, the through hole 32 of the valve body 9 causes the seal member 5 to pass through.
4, the high pressure air in the pressure accumulation chamber 51 is opened to the pressure accumulation chamber 51.
3 and flows into the air chamber 18, and the check valve 27 closes the atmosphere passage 20. Then, like the first embodiment, this high-pressure air flows into the working pressure chamber 7 through the communication passage 20, and a large differential pressure is generated between the negative pressure chamber 6 and the working pressure chamber 7, A large forward thrust is generated in the power piston 5. Therefore, according to the second embodiment, the atmosphere passage and the high-pressure air passage are mechanically switched with respect to the working pressure chamber 7 according to the movement amount of the valve body 9, so that the first embodiment is different from the first embodiment. The structure is simpler because it is not necessary to provide a special on-off valve 36.

[0024]

As described above in detail, according to the pneumatic booster according to the present invention, the circumference of the housing becomes simple, so that the mountability on the vehicle is improved, and moreover,
No special sensors or control circuits are required, and the structure can be simplified and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing an overall structure of a pneumatic booster according to a first embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view showing a main part of the pneumatic booster shown in FIG.

FIG. 3 is a sectional view showing an overall structure of a pneumatic booster according to a first embodiment of the present invention.

4 is an enlarged cross-sectional view showing a main part of the pneumatic booster shown in FIG.

[Explanation of symbols] 1 housing 4 diaphragm 5 power piston 6 negative pressure chamber 7 working pressure chamber 9 valve body 14 plunger 15 guide member 16 input shaft 19 negative pressure passage 20 atmosphere passage 21 communication passage 23 valve seat (first valve 24) valve seat (first valve mechanism) 25 valve member (first valve mechanism) 26 valve spring (first valve mechanism) 27 check valve (second valve mechanism) 31 through hole (high pressure air) 34) High pressure air source 32 Casing 36 Open / close valve (second valve mechanism) 41 Stepped portion (second valve mechanism) 51 Accumulation chamber 54 Seal member (second valve mechanism)

Claims (1)

[Claims] 1. A housing is divided into a negative pressure chamber and a working pressure chamber by a power piston having a diaphragm, and a valve body having a negative pressure passage, an atmosphere passage and a high pressure air passage is attached to the power piston, and A first valve body that slidably extends through the housing and extends to the rear of the housing, and switches the negative pressure passage and the atmosphere passage with respect to the working pressure chamber in the valve body in cooperation with the input shaft. And a second valve mechanism around the valve body for switching between the atmosphere passage and the high pressure air passage with respect to the working pressure chamber according to the movement amount of the valve body with respect to the housing. A pneumatic booster characterized in that it is arranged in a special manner.