JP3743969B2 - Pneumatic booster - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic booster used in a vehicle brake system.
[0002]
[Prior art]
Conventionally, a pneumatic booster generally divides a shell body into a constant pressure chamber and a variable pressure chamber by a power piston provided with a diaphragm, and inserts the shell body into the power piston so that a cylindrical portion extends backward. And a poppet valve that selectively communicates the variable pressure chamber with the constant pressure chamber and the atmosphere by contacting and separating from the valve plunger in conjunction with the input shaft in the valve body. And a differential pressure is generated between the constant pressure chamber and the variable pressure chamber by the operation of the valve mechanism to advance the power piston.
[0003]
In this type of pneumatic booster, when the brake pedal operatively connected to the input shaft is in the released state, the pressure in the constant pressure chamber (usually negative pressure) is introduced into the variable pressure chamber, but it becomes inactive. 2. Description of the Related Art In recent years, so-called automatic output type pneumatic boosters have been developed that automatically introduce the atmosphere into a variable pressure chamber and automatically output it as necessary.
[0004]
Conventionally, in order to make the above-described general pneumatic booster an automatic output type, for example, in the one described in JP-A-60-197454, the valve mechanism that performs the boosting action in the valve body is Separately, an auxiliary valve is arranged, and this auxiliary valve is moved by an actuator arranged outside the shell body, and the negative pressure passage leading to the variable pressure chamber is shut off regardless of the valve mechanism, while connected to the shell body. An air pipe independent from the valve body is opened by an opening / closing valve to introduce the atmosphere into the variable pressure chamber.
[0005]
[Problems to be solved by the invention]
However, according to the automatic output type pneumatic booster described in the above publication, in addition to the existing valve mechanism involved in the boosting action, two new valve mechanisms are required, which increases the cost burden. There was a problem.
[0006]
The present invention has been made in view of the above-mentioned conventional problems, and the problem is that the installation of a new valve mechanism is not required by adding improvements to the existing valve mechanism, so that a general pneumatic pressure doubling is achieved. The force device is to be an automatic output type at low cost.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention according to claim 1 is characterized in that a valve plunger constituting a valve mechanism in a valve body is slidably fitted to a plunger main body connected to the input shaft and the plunger main body. formed from a cylindrical valve seat member, further the valve seat member is provided with operating means for selectively displacing the position away from the position and the poppet valve to abut against the said poppet valve, said operating means An urging means that is built in the valve body and normally urges the valve seat member in a direction to abut against the poppet valve, and is slidably fitted to the outer periphery of the tubular portion of the valve body, and has a tip portion on the valve seat member. It is characterized in that it comprises a sleeve operatively connected to the side, and a driving means for sliding the sleeve to displace the valve seat member in a direction away from the poppet valve .
In the pneumatic booster configured as described above, the atmosphere is automatically introduced into the variable pressure chamber when the valve seat member of the valve plunger is separated from the poppet valve by the operating means.
[0008]
According to a second aspect of the present invention, the drive means includes a variable volume annular chamber formed around a sleeve as an inner peripheral wall, and a pressure change for selectively supplying air and negative pressure into the chamber. And a means for sliding the sleeve by a pressure difference between the inside and outside of the chamber .
[0009]
Furthermore, in the invention according to claim 3, the valve body is provided with a radial hole, and the distal end side of the sleeve is operatively connected to the valve seat member via a connecting member inserted into the radial hole. It is characterized by.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0011]
1 to 3 show a pneumatic booster as a first embodiment of the present invention. This pneumatic booster is configured as a tandem type, and the inside of the shell body 1 composed of the front shell 2 and the rear shell 3 is partitioned into two front and rear chambers by a center shell 4, These are divided into constant pressure chambers 9 and 10 and variable pressure chambers 11 and 12 by power pistons 7 and 8 having diaphragms 5 and 6. A valve body 13 disposed on the axial center of the shell body 1 is fitted and supported on each power piston 7, 8. The valve body 13 connects the center shell 4 and the rear shell 3 via seal members 14, 15. The cylindrical portion 13a on the rear end side extends rearward of the rear shell 3 so as to be airtight and slidable.
[0012]
The valve body 13 is provided with a constant pressure passage (negative pressure passage) 16 that communicates the two constant pressure chambers 9 and 10 and communicates the constant pressure chambers 9 and 10 with each other in the tubular portion 13a of the valve body 13, An air passage (atmospheric passage) 17 is provided that connects the two variable pressure chambers 11 and 12 and connects the variable pressure chambers 11 and 12 into the tubular portion 13 a of the valve body 13. Each of the negative pressure passage 16 and the atmospheric passage 17 includes axial holes 16a and 17a and radial holes 16b and 17b formed in the valve body 13. For example, engine negative pressure is introduced into the constant pressure chamber 9 on the front side through an introduction pipe 18 connected to the front portion of the front shell 2, while on the opening side of the small diameter portion of the valve body 13. A silencer 19 and a filter 20 are provided.
[0013]
A valve mechanism 21 is provided in the valve body 13 to selectively open the negative pressure passage 16 and the atmospheric passage 17 with respect to the front and rear variable pressure chambers 11 and 12. The valve mechanism 21 includes a valve plunger 22 slidably fitted in the valve body 13 and an elastically deformable poppet whose base end is fixed to the inner surface of the valve body 13 using a pressing member 23 (FIG. 2). And a valve 24.
[0014]
2 and 3, the valve plunger 22 includes a plunger main body 25 slidably inserted into a shaft hole provided in the valve body 13, and a seal member 26 interposed between the plunger main body 25 and a seal member 26. A cylindrical valve seat member 28 having an atmospheric valve seat 27 which is fitted in an airtight and slidable manner and which can be brought into contact with the inner edge portion of the front end of the poppet valve 24 at one end. The valve seat member 28 is slidably fitted to the plunger body 25, and a spring 30 interposed between a spring receiver 29 whose one end is in contact with the valve seat member 28 and a stepped surface in the valve body 13, Normally, the valve seat 27 is biased in a direction in which the valve seat 27 is brought into contact with the poppet valve 24. The valve seat member 28 is also prevented from coming out of the plunger body 25 by engaging a step portion 28a provided on the inner periphery thereof with a flange 25a provided at one end of the plunger body 25. In this state, The front end of the seat member 28 (the valve seat 27 side) protrudes from the plunger main body 25 by a predetermined distance. An input shaft 31 extending from a brake pedal (not shown) is connected to the rear end portion of the plunger body 25, and the plunger body 25 and the valve seat member are moved forward when the input shaft 31 advances in the left direction in the figure. It moves to the left integrally with 28.
[0015]
The valve mechanism 21 also includes a negative pressure valve seat 32 formed on the inner peripheral surface of the valve body 13 so as to include the open end of the negative pressure passage 16, and the outer edge of the front end of the poppet valve 24 is the valve edge. The seat 32 is adapted to be detached from and seated. The poppet valve 24 is normally urged in a direction to be seated on the negative pressure valve seat 32 by a valve spring 33 having one end engaged with the input shaft 31. In addition, a first return spring 34 (see FIG. 5) between the input shaft 31 and the pressing member 23 that fixes the poppet valve 24 normally biases the input shaft 31, that is, the plunger main body 25 in the backward direction (brake pedal side). 2) is installed. The plunger body 25 of the valve plunger 22 is restricted from moving toward the input shaft 31 by a stop key 35 inserted into the radial hole 17b constituting the atmospheric passage 17, and the valve is moved in a state where this movement is restricted. The seat member 28 is positioned at a position where it abuts against the poppet valve 24. Accordingly, the set load of the spring 30 that biases the valve seat member 28 is set to be larger than the set load of the valve spring 33, and thus the valve seat member 28 uses the poppet valve 24 for negative pressure when the apparatus is not operating. It acts to lift slightly from the valve seat 32.
[0016]
The entire valve body 13 is urged toward the input shaft 31 by a second return spring 36 (FIG. 1) disposed in the front-side constant pressure chamber 9, and the stop key 35 is placed on the inner surface of the rear shell 3 when not operating. It is positioned at the return end to be brought into contact with the fixed stopper plate 37 (FIG. 2). In addition, a base end large diameter portion 39a of the output shaft 39 is operatively connected to the center of the front end portion of the valve body 13 via a rubber reaction disk 38. The reaction disk 38 has a central portion facing the valve plunger 22 and forms a gap 40 of a predetermined size between the reaction disk 38 and the valve plunger 22 in the inoperative state shown in the figure. The output shaft 39 is inserted through the front shell 2 in an airtight manner and extends forward, and a master cylinder (not shown) is operatively connected thereto.
[0017]
On the other hand, a sleeve 41 is fitted into the tubular portion 13a of the valve body 13 through a seal member 42 so as to be airtight and slidable. The sleeve 41 is slidably inserted through an existing seal member 15 that is attached to the rear shell 3 and guides the valve body 13, and extends at the tip thereof into the rear shell 3. In the rear shell 3, the tip of the sleeve 41 is brought into contact with a key member 44 inserted into a radial hole 43 provided in the valve body 13. The tip of the key member 44 is press-fitted into an annular groove 28 b (FIG. 3) provided on the outer periphery of the valve seat member 28 of the valve plunger 22. The radial hole 43 is a long hole that is long in the axial direction of the valve plunger 22, and the valve seat member 28 is within a range in which the key member 44 can move within the radial hole 42, and the valve body 13 is connected to the valve body 13. Relative movement is allowed.
[0018]
Outside the rear shell 3, an annular chamber 46 is formed around the cylindrical portion 13 a of the valve body 13 with the sleeve 41 as an inner peripheral wall and a cover 45 as an outer peripheral wall. The front end of the cover 45 is hermetically fixed to the rear surface of the rear shell 3 by a fixing block 47. On the other hand, the sleeve 41 slides the outer flange 41a provided at the rear end on the inner surface of the cover 45 via the seal member 48. Touching. The sleeve 41 is restricted from moving backward by an inward flange 45 a provided at the rear end of the cover 45.
[0019]
The fixed block 47 is provided with a through hole 49 that communicates with the chamber 46 through a notch 41 b (FIG. 2) provided at the distal end of the sleeve 41. The negative pressure source of the pressure changing means 53 including the vacuum pump 51 and the vacuum tank 52 is connected by a pipe 54 (FIG. 1). The pressure changing means 53 serves to selectively switch the inside of the chamber 46 between the atmosphere and a negative pressure source, and the electromagnetic switching valve 50 is normally provided as a normally open valve that connects the atmosphere side to the chamber 46. It has been. When the electromagnetic switching valve 50 is switched from this state, the negative pressure in the vacuum tank 52 is supplied into the chamber 46, and as a result, the sleeve is caused by the pressure difference between the inside and outside of the sleeve 41 with the outer flange 41a interposed therebetween. 41 is pulled into the shell body 1 and the key member 44 is pushed forward at the tip thereof.
[0020]
The pneumatic booster described above is attached to the vehicle body using a plurality of stud bolts 55 planted on the rear surface of the rear shell 3, and a brake pedal (not shown) is connected to the input shaft 31 in this attached state. Normally, the atmosphere is introduced into the chamber 46, the sleeve 41 is at the retracted end, and the valve seat member 28 of the valve plunger 22 brings the valve seat 27 into contact with the poppet valve 24. When the brake pedal is depressed from this state, the input shaft 31 moves forward and the plunger main body 25 and the valve seat member 28 constituting the valve plunger 22 move integrally in the left direction in the figure, and the atmosphere of the valve seat member 28 is increased. The valve seat 27 is opened and air flows into the valve body 13 through the silencer 19 and the filter 20, and this air is introduced into the two variable pressure chambers 12 and 11 through the air passage 17 (17 b and 17 a). As a result, a differential pressure is generated between the constant pressure chambers 9 and 10 into which the negative pressure is introduced and the variable pressure chambers 11 and 12, and the front and rear power pistons 7 and 8 move forward to boost the output. A part of the output reaction force at that time is transmitted from the reaction disk 38 to the brake pedal via the plunger body 25 and the input shaft 31 through the body 13. At the start of this boosting action, a so-called jump-in output is generated in which the output increases regardless of the input until the gap 40 between the plunger body 25 and the reaction disk 38 is eliminated. The output increases as the input increases.
[0021]
On the other hand, when the pedaling force disappears from the brake pedal, the input shaft 31 moves (retreats) in the right direction by the restoring force of the first return spring 34, and the plunger body 25 also retracts. Then, the valve seat member 28 is retracted by the spring force of the spring 30 and the valve seat 27 comes into contact with the poppet valve 24 and slightly lifts it from the negative pressure valve seat 32. As a result, the constant pressure chambers 9 and 10 Negative pressure is introduced into both the variable pressure chambers 11 and 12, and the above-described differential pressure is eliminated. Thereafter, the valve body 13 is moved in the return direction by the spring force of the second return spring 36, the stop key 35 comes into contact with the stopper plate 37 in the rear shell 3, and the retreat thereof is stopped. Return to the position (inactive).
[0022]
Here, when the negative pressure is introduced into the chamber 46 by operating the switching valve 50 in the pressure changing means 53 from the inoperative state described above, the sleeve 41 is drawn into the shell body 1 as shown in FIG. The tip pushes the key member 44 forward. Then, the valve seat member 28 constituting the valve plunger 22 moves forward against the biasing force of the spring 30, and the poppet valve 24 is seated on the negative pressure valve seat 32, while the atmospheric valve seat 27 is moved from the poppet valve 24. Separate. As a result, even though the brake pedal is not depressed, the atmospheric pressure is introduced into the two variable pressure chambers 12 and 11 through the atmospheric passage 17 (17b and 17a), and the constant pressure chamber 9 and the negative pressure are introduced. A differential pressure is generated between the variable pressure chamber 10 and the variable pressure chambers 11 and 12, and the front and rear power pistons 7 and 8 move forward to automatically generate a predetermined output. In this embodiment, the spring 30, sleeves 41 are operatively connected through the key member 44 on the valve seat member 28, the chamber 46 by sliding the sleeve 41 for biasing the valve seat member 28, the chamber 46 The pressure changing means 53 or the like for changing the internal pressure constitutes an operating means for selectively displacing the valve seat member 28 between a position in contact with the poppet valve 24 and a position away from the poppet valve 24. Yes.
[0023]
FIG. 5 shows a second embodiment of the present invention. The feature of the second embodiment is that the cover 45 in the first embodiment is divided into two in the longitudinal direction from substantially the center, and the front side is fixed from the fixed cylinder 60 which is a rigid body, and the rear side is set. The rubber bellows 61 is formed from each. In this case, the fixed cylinder 60 is fixed to the rear shell 3 by the fixing block 47, while the bellows 61 is directly coupled to the outer flange 41a at the rear end of the sleeve 41. In the second embodiment, when negative pressure is supplied into the chamber 46 by the operation of the switching valve 50 (FIG. 1), the bellows 61 is reduced to assist in pulling the sleeve 41 into the shell body 1. In addition, the retraction of the sleeve 41 becomes more reliable. Moreover, since there is no sliding portion (seal member 48) between the sleeve 41 and the cover 43, the movement of the sleeve 41 is ensured for a long time.
[0024]
In the above two embodiments, the pressure to be introduced into the chamber 46 is changed by the pressure changing means 53 and the pressure difference between the inside and outside of the chamber 46 is automatically output, so that the operation unit The position where the pressure changing means 53 is provided is not limited, and the degree of freedom of installation of the operation unit with respect to the vehicle increases. Incidentally, in the device described in the above-mentioned Japanese Patent Application Laid-Open No. 60-197454, the auxiliary valve is mechanically operated by an actuator arranged outside the shell body, so that the valve body that moves forward greatly at the time of boosting action. The position of the actuator as the operation unit is limited (fixed to the input shaft in the device described in the publication), and the degree of freedom of installation in the vehicle is reduced.
[0025]
In the above-described two embodiments, the chamber 46 is connected to the vacuum pump 51 and the vacuum tank 52 (negative pressure source), and negative pressure is supplied from the vacuum pump 51 into the chamber 46. The negative pressure source may be omitted, and the engine negative pressure supplied to the constant pressure chamber 9 may be supplied to the chamber 46.
In the above two embodiments, the spring 30, the sleeve 41, the chamber 46, the pressure changing means 53, etc. are used as the operating means for operating the valve seat member 28 constituting the valve plunger 22. For example, the sleeve 41 may be operatively connected to the valve seat member 28, and the sleeve may be mechanically slid by a driving unit provided outside the shell body 1. However, in this case, the drive unit needs to be interlocked with the input shaft 31.
Furthermore, in the above-described two embodiments, an example in which the tandem type is configured has been shown. However, the present invention includes a single type in which a constant pressure chamber and a variable pressure chamber are provided, respectively. is there.
[0026]
【The invention's effect】
As described above, according to the first aspect of the present invention, the existing valve plunger has a double structure, and one of the valve plungers is automatically operated by the operating means so that it is necessary to newly provide a valve mechanism. This has the effect of minimizing cost increases.
Further, according to the first aspect of the present invention, since the sleeve can be automatically output only by sliding the sleeve in one direction by the driving means, the driving means can have a simple structure.
Furthermore, according to the invention described in claim 2 , since the sleeve is slid by the pressure difference between the inside and outside of the chamber, the degree of freedom of installation of the operation unit in the vehicle is increased and the utility value is increased. .
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing the overall structure of a tandem-type pneumatic booster as 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.
3 is an enlarged cross-sectional view showing a main part of the pneumatic booster shown in FIG. 2. FIG.
4 is a cross-sectional view showing an automatic output action of the pneumatic booster shown in FIG. 1. FIG.
FIG. 5 is a cross-sectional view showing the main structure of the tandem pneumatic booster according to the first embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Shell main body 5, 6 Diaphragm 7, 8 Power piston 9, 10 Constant pressure chamber 11, 12 Transformer chamber 13 Valve body 13a Tubular part 21 of valve body 21 Valve mechanism 22 Valve plunger 24 Poppet valve 25 Plunger main body 28 Valve seat member 30 Spring (Biasing means)
31 Input shaft 39 Output shaft 41 Sleeve 44 Key member 45 Cover 46 Chamber 50 Electromagnetic switching valve 51 Vacuum pump 53 Pressure changing means 60 Fixed cylinder 61 Bellows

Claims (3)

The inside of the shell body is partitioned into a constant pressure chamber and a variable pressure chamber by a power piston provided with a diaphragm, and a valve body is inserted into the power piston, and the tubular body is extended to the rear thereof, and the valve body is supported. A valve mechanism including a valve plunger interlocked with the input shaft and a poppet valve in contact with and separating from the valve plunger and selectively communicating the variable pressure chamber with the constant pressure chamber and the atmosphere; In a pneumatic booster that causes the power piston to move forward by generating a differential pressure between the constant pressure chamber and the variable pressure chamber by the operation of a mechanism, the plunger main body connected to the input shaft And a cylindrical valve seat member slidably fitted to the plunger main body, and further, the valve seat member is spaced from the poppet valve at a position where it abuts the poppet valve. Operating means for selectively displacing the position provided, wherein the operating means includes a biasing means always decorated on the valve body for biasing in a direction abutting the valve seat member to the poppet valve, cylindrical the valve body A sleeve that is slidably fitted on the outer periphery of the member and operatively connected to the valve seat member on the distal end side, and a drive means that slides the sleeve and displaces the valve seat member away from the poppet valve. A pneumatic booster characterized by comprising: The drive means includes an annular chamber having a variable volume formed around the sleeve as an inner peripheral wall, and pressure changing means for selectively supplying the atmosphere and negative pressure into the chamber. The pneumatic booster according to claim 1 , wherein the sleeve is slid by a pressure difference . The radial direction hole is provided in the said valve body, The front-end | tip part side of the said sleeve is operatively connected to the said valve seat member via the connection member inserted in this radial direction hole, The Claim 1 or 2 characterized by the above-mentioned. Pneumatic booster.

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