JP4103012B2 - Pneumatic booster - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a pneumatic booster used in a brake system such as a vehicle.
[0002]
[Prior art]
In general, a pneumatic booster is configured to divide a housing into a negative pressure chamber and a working pressure chamber by a power piston having a diaphragm, and attach a valve body having a negative pressure passage and an atmospheric passage to the power piston. A valve mechanism is provided in the valve body for switching the negative pressure passage and the atmospheric passage with respect to the working pressure chamber, and the valve mechanism is linked with an input shaft to introduce the atmosphere into the working pressure chamber. The power piston is configured to generate a boosted force by the differential pressure between the pressure chamber and the working pressure chamber. However, according to such a general pressure type 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 can be obtained. Then, 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, so that the entire size cannot be increased.
[0003]
Recently, therefore, development of a pneumatic booster in which high-pressure air is introduced into the working pressure chamber to further increase the thrust has been promoted. For example, Japanese Utility Model Laid-Open No. 5-32209 discloses an electromagnetic on-off valve in the working pressure chamber. A high-pressure air source is connected via the valve body, and valve means (check valve) for shutting off the atmospheric passage is provided in the valve body (valve cylinder), based on signals from brake sensors, vehicle speed sensors, load sensors, etc. And a pressure-type pneumatic booster that opens the electromagnetic on-off valve and introduces high-pressure air into the working pressure chamber to increase the differential pressure between the negative pressure chamber and the working pressure chamber. See paragraphs 22 and 23 of the description).
[0004]
[Problems to be solved by the invention]
However, according to the pressurization type pneumatic booster described in the above publication, an electromagnetic on-off valve that cuts off high-pressure air is provided independently from the housing. There was a problem that the installation of was troublesome. In addition, since the on-off valve is controlled based on signals from various sensors, a special control circuit is required, which not only complicates the overall structure of the apparatus but also increases the cost.
[0005]
The present invention has been made in view of the above-described conventional problems, and the object of the present invention is to simplify the surroundings of the housing to improve the mounting property to the vehicle and to eliminate the need for special sensors and control circuits. An object of the present invention is to provide a pressure-type pneumatic booster that achieves simplification of structure and cost reduction.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, in the invention according to claim 1, the housing is partitioned into a negative pressure chamber and a working pressure chamber by a power piston provided with a diaphragm, and a negative pressure passage and an atmospheric air are provided in the power piston. A valve body having a passage and a high-pressure air passage is mounted, the thrust of the power piston is transmitted to the output shaft through the valve body and the reaction disk , and a part of the reaction force of the reaction disk is operatively connected to the input shaft. A first valve mechanism that switches between the negative pressure passage and the atmospheric passage for the working pressure chamber, and the working pressure chamber for the working pressure chamber. A second valve mechanism for switching between the atmospheric passage and the high-pressure air passage is disposed; and the first and second valve mechanisms are operatively connected to an input shaft; Opening the air passage in response to relative movement between the valve body and the input shaft, said second valve mechanism, when a predetermined force or more force to the input shaft is given, from the reaction disc The rod member fixed to the plunger that transmits the reaction force and the input shaft move relative to each other to open the high-pressure air passage.
[0007]
In the invention according to claim 2, the housing is partitioned into a negative pressure chamber and a working pressure chamber by a power piston having a diaphragm, and a negative pressure passage, an atmospheric passage and a high pressure air passage are provided in the power piston. A valve body having a valve body, a thrust of the power piston being transmitted to the output shaft through the valve body and the reaction disk, and a part of the reaction force of the reaction disk being operatively connected to the input shaft via a plunger. so as to transmit Te, in the hollow shaft portion of the valve body, a first valve mechanism for switching between the air passage and the negative pressure passage with respect to the working pressure chamber, and the air to the working pressure chamber A second valve mechanism for switching between the passage and the high-pressure air passage is provided, and the first and second valve mechanisms are operatively connected to an input shaft, and the first valve mechanism is connected to the input shaft. The input shaft is configured to open the atmospheric passage according to relative movement with the valve body, and the second valve mechanism includes a valve seat formed in the middle of the high-pressure air passage and a valve body that is always seated on the valve seat. An on-off valve that is linked to the on-off valve, a rod member that is movable relative to the on-off valve and that transmits a reaction force from the reaction disk , and an end that abuts the rod member so that the on-off valve is in contact with the rod member. and a spring for biasing the input shaft side, when a predetermined force or more force to the input shaft is given, the input of said valve body to open the high pressure air passage is separated from the valve seat The shaft and the rod member are configured to move relative to each other.
[0008]
[Action]
In the pneumatic booster configured as described above, in addition to the first valve mechanism that switches the negative pressure passage and the atmospheric passage with respect to the working pressure chamber, the atmospheric passage and the high pressure air passage with respect to the working pressure chamber. Since the second valve mechanism for switching is also disposed in the valve body, the area around the housing is simplified. Further, since the first and second valve mechanisms are operatively connected to the input shaft and these valve mechanisms are mechanically operated in conjunction with the input shaft, special sensors and control circuits are not required. Furthermore, the second valve mechanism is configured to open the high-pressure air passage when a force greater than a predetermined force is applied to the input shaft, so that the passage is smoothly switched from the atmosphere side to the high-pressure air side. A large braking force can be obtained with good timing during high deceleration braking or sudden braking.
[0009]
【Example】
Embodiments of the present invention will be described below with reference to the accompanying drawings.
1 and 2, reference numeral 1 denotes a housing composed of a front shell 2 and a rear shell 3, the interior of which is divided into two front and rear chambers by a center shell 4. The front chamber further includes a power piston provided with a diaphragm 5. 6 is divided into two front and rear chambers. The front chamber in the housing 1 defined by the power piston 6 is configured as a negative pressure chamber 7, and the rear chamber is configured as a working pressure chamber 8, and the negative pressure chamber 7 is passed through a negative pressure introduction port 9 provided in the front shell 2. For example, a negative pressure is introduced from a negative pressure source (not shown) such as an intake manifold of the engine. On the other hand, the rear chamber in the housing 1 partitioned by the center shell 4 is configured as a pressure accumulating chamber 10, in which a later-described additional chamber provided independently of the housing 1 is provided through a high-pressure inlet 12 provided in the rear shell 3. High pressure air is supplied from the pressurized air source 11.
[0010]
Reference numeral 13 denotes a valve body disposed in the housing 1. The valve body 13 includes a main body portion 14 having a large diameter and a hollow shaft portion 15 having a small diameter. The main body portion 14 is coupled to the diaphragm 5 and the power piston 6, and the hollow shaft portion 15 is connected to the rear shell 3 and the center shell 4. And slidably supported via a seal member 16. The hollow shaft portion 15 of the valve body 13 extends through the rear shell 3 to the rear of the housing 1, and an input shaft 17 that interlocks with a brake pedal (not shown) is inserted therein. The entire valve body 13 is biased toward the input shaft 17 by a return spring 18 disposed in the negative pressure chamber 7 of the housing. Further, a portion of the hollow shaft portion 15 of the valve body 13 protruding outside the housing 1 is covered with a dust boot 19.
[0011]
The valve body 13 is provided with a negative pressure passage 20, a ventilation passage 21, and a high pressure air passage 22 that communicate with the negative pressure chamber 7, the working pressure chamber 8, and the pressure accumulation chamber 10 in the hollow shaft portion 15. . Further, a stepped shaft hole 23 is provided in the main body portion 14 of the valve body 13, and a plunger 24 is slidably fitted into a small diameter portion of the shaft hole 23. An annular groove 24a is formed in the middle of the plunger 24 in the axial direction, and a stopper piece 25 loosely inserted into the air passage 21 from the outer periphery of the valve body 13 is fitted into the annular groove 24a. The stopper piece 25 is slightly movable in the vent passage 21 in the axial direction of the valve body 13, and the plunger 24 is also slidable in the axial direction within the movement range of the stopper piece 25. A large diameter portion of the shaft hole 23 of the valve body 13 accommodates a large diameter portion of the base end of the output shaft 27 via a rubber reaction disk 26. The distal end portion of the output shaft 27 extends through the front shell 2 to the front of the housing 1, and a master cylinder (not shown) is operatively connected thereto.
[0012]
On the other hand, an annular guide member 28 is fitted into the hollow shaft portion 15 of the valve body 13, and an operating rod 29 described later is slidably fitted into the guide member 28. Guide member 28, while being inserted from the rear of the housing 1 until seated in the step 15a of the hollow shaft portion 15, the stopper piece 30 which are implanted therein from the outer periphery of the hollow shaft portion 15 from the hollow shaft section 15 Omission is regulated. The guide member 28 has an axial hole (atmospheric passage) 31 that opens at both ends thereof, a circumferential groove 32 that receives the stopper piece 30, and a radial hole 33 that opens at the bottom and inner circumference of the circumferential groove 32. Is provided. In a state where the guide member 28 is seated on the step 15 a in the hollow shaft portion 15, the circumferential groove 32 is aligned with the high-pressure air passage 22, and the high-pressure air in the pressure accumulating chamber 10 is the high-pressure air passage 22, the guide member 28. Are introduced to the working rod 29 via the circumferential groove 32 and the radial hole 33 thereof.
[0013]
As shown in FIG. 2, the front end side of the guide member 28 is a small-diameter portion 28a slightly smaller than the inner diameter of the hollow shaft portion 15 of the valve body 13, and the small-diameter portion 28a is provided with a valve member via a seal member 34. 35 is slidably mounted. The valve member 35 includes a cylindrical guide portion 35a fitted to the guide member 28, and a valve portion 35b formed in an inward flange shape at the distal end of the guide portion 35a, and the entirety thereof is an inner metal. It has a two-layer structure in which a rubber seal plate 37 is vulcanized and bonded to the outer surface of the plate 36. Thus, an annular valve seat portion 38 including the opening edge of the negative pressure passage 20 is formed on the inner peripheral surface of the hollow shaft portion 15 of the valve body 13, and an annular valve seat is also formed at the rear end of the plunger 24. A seat portion 39 is formed, and the valve portion 35b of the valve member 35 can be attached to and detached from these valve seat portions 38 and 39.
[0014]
A valve spring 40 is disposed inside the valve member 35. The valve spring 40 has one end engaged with the inside of the valve portion 35b of the valve member 35 and the other end interposed through the valve seat 41. The guide member 28 is engaged with the front end. Due to the presence of the valve spring 40, the valve member 35 is maintained in a state of being seated on the valve seat portions 38 and 39 when the booster is not in operation, and the valve seat 41 is in contact with the front end of the guide member 28. The state where the atmospheric passage 31 is closed is maintained. The valve member 35, the valve seat portions 38 and 39, the valve spring 40, etc. constitute a first valve mechanism 42 that switches the negative pressure passage 20 and the atmospheric passage 31 with respect to the working pressure chamber 8, and the right side of the plunger 24. Alternatively, in accordance with the movement in the left direction, the negative pressure passage 20 and the atmospheric passage 31 are selectively communicated with the working pressure chamber 8 via the vent passage 21 (FIG. 1).
[0015]
The operating rod 29 in the guide member 28 has a rear end operatively connected to the input shaft 17, and a front end operatively connected to the plunger 24 via a second valve mechanism 43. The actuating rod 29 is formed with a radial hole 44 that can communicate with the radial hole 33 of the guide member 28 and a stepped axial hole 45 that connects the radial hole 44 to the tip. The second valve mechanism 43 is disposed on the axis of the valve body 13 and has a fixed pin 46 as a rod member whose one end is screwed and fixed to the plunger 24, and a force greater than a predetermined value is applied to the input shaft 17. At this time , the on-off valve 47 provided so as to be movable relative to the fixed pin 46 and one end of the on-off valve 47 provided integrally with the fixed pin 46 are brought into contact with the on-off valve 47 to the operating rod 29 side. A spring 49 is provided, and a stopper 50 is engaged with one end of the spring receiver 48 to restrict movement of the on-off valve 47 toward the operating rod 29 side.
[0016]
More specifically, as shown in FIG. 2, the opening / closing valve 47 has one end slidably fitted to the fixing pin 46 via the seal member 51 and the other end connected to the axial hole 45 of the operating rod 29. ball seated with the seat member 52 is press-fitted, at one end of the seat surface 52a of the sheet member (the valve seat) 52 receives the urging force of the axial bore 45 disposed valve in the spring 53 of the rod 29 (the valve Body) 54. The sheet member 52 is formed with an axial hole 55 having one end opened on the sheet surface 52a and a radial hole 56 connecting the axial hole 55 to a side surface. Further, the distal end side of the fixed pin 46 is a small diameter portion 46 a, and the fixed pin 46 is inserted into the axial hole 55 of the sheet member 52.
[0017]
Here, in the inoperative state of the booster, the on-off valve 47 is positioned at the moving end (extension end) toward the operating rod 29 by the action of the spring 49 and the stopper 50 as shown in the figure. In this state, the distal end of the fixing pin 46 (the distal end of the small-diameter portion 46a) is positioned at a position close to the ball 54, whereby the ball 54 maintains a state in which the axial hole 55 of the seat member 52 is closed, and the guide High-pressure air does not flow in front of the member 28. Even when the force applied to the operating rod 29 from the input shaft 17 is smaller than the force of the spring 49, the on-off valve 47 is positioned at the extended end, and the high-pressure air does not flow in front of the guide member 28 as described above. In this case, the force applied from the input shaft 17 to the operating rod 29 is transmitted to the plunger 24 as it is through the on-off valve 47 and the fixing pin 46, so that only the first valve mechanism 42 operates. become. On the other hand, when the force applied to the operating rod 29 from the input shaft 17 becomes larger than the force of the spring 49, the spring 49 is bent and the fixed pin 46 and the on-off valve 47 move relative to each other. As a result, the ball 54 is pushed by the fixed pin 46. It is opened and high-pressure air flows in front of the guide member 28.
[0018]
The high-pressure air source 11 includes a compressor 58 directly connected to the high-pressure inlet 12 of the housing 1 via a pipe 57, and two check valves 59 and an air dryer 60 interposed in the middle of the pipe 57. I have. Further, the same negative pressure source as that for the negative pressure chamber 7 of the housing 1 is connected to a portion of the pipe 57 located between the two check valves 59 via a negative pressure pipe 61. An electromagnetic opening / closing valve 62 is interposed.
[0019]
Hereinafter, the operation of the pneumatic booster configured as described above will be described.
In the inoperative state shown in FIGS. 1 and 2, negative pressure is confined in the working pressure chamber 8. When the brake pedal is depressed from this state, the input shaft 17 moves (advances) and the operating rod 29 advances in the left direction in the figure. At this time, the force applied to the input shaft 17 is the spring of the second valve mechanism 43. If the force is less than 49, the plunger 24 is interlocked with the movement of the operating rod 29, and the valve seat portion 39 of the plunger 24 is separated from the valve portion 35b of the valve member 35. Then, the negative pressure in the working pressure chamber 8 is introduced in front of the guide member 29, the valve seat 41 is opened, and the atmosphere flows from the atmospheric passage 31 to the front of the guide member 29. This atmosphere is introduced into the working pressure chamber 8 through the air passage 21, and as a result, a differential pressure is generated between the working pressure chamber 8 and the working pressure chamber 8 into which the engine negative pressure is introduced, thereby causing the power piston. 6 generates a forward thrust. This thrust is transmitted to the master cylinder (not shown) via the valve body 13, the reaction disk 26 in the valve body 13, and the output shaft 27, and a boosting action is started. At the time of this boosting action, the reaction disk 26 is elastically deformed, and a part thereof projects into the shaft hole 23 of the valve body 13, and the reaction force is transmitted to the input shaft 17 through the plunger 24 and the operating rod 29. The
[0020]
When the brake pedal is further stepped on and a force larger than the force of the spring 49 is applied from the input shaft 17 to the operating rod 29, the spring 49 is bent and the fixed pin 46 and the on-off valve 47 move relative to each other. The ball 54 is pushed open by 46. Then, the high-pressure air in the pressure accumulating chamber 10 flows into the high-pressure air passage 22 of the hollow shaft portion 15 of the valve body 13, the circumferential groove 32 of the guide member 28 and its radial hole 33, the radial hole 44 of the actuating rod 29, and It flows into the front of the actuating rod 29 via the axial hole 45 and the axial hole 55 and radial hole 56 of the seat member 52 of the on-off valve 47. The valve seat 41 is pressed against the end face of the guide member 28 by the inflow of the high-pressure air, and the atmospheric passage 31 is closed. At the same time, the high-pressure air flows into the working pressure chamber 8 through the air passage 21. As a result, a larger differential pressure is generated between the negative pressure chamber 7 and the working pressure chamber 8, and the power piston 6 moves forward. A large thrust is generated. Therefore, if the spring 49 of the second valve mechanism 43 has a spring force slightly smaller than the input generated at the input shaft 17 at the time of high deceleration braking or sudden braking, the spring 49 at the time of high deceleration braking or sudden braking is selected. Sometimes a large braking force can be obtained.
[0021]
When the pedal force is lost from the brake pedal, the plunger 24 is pushed by the reaction disk 26 and moves to the right, and the valve seat 39 of the plunger 24 contacts the valve seat 38 of the valve member 35 accordingly. The valve member 35 is moved in the right direction. As a result, the introduction of the atmosphere or the high-pressure air into the working pressure chamber 8 is interrupted, while the negative pressure in the negative pressure chamber 7 is introduced into the working pressure chamber 8 via the negative pressure passage 20 and the air passage 21. The differential pressure is reduced and the thrust is reduced. When the brake pedal is fully opened, the valve body 13 is returned to the original position by the pressing force of the return spring 18, and the valve member 35 is seated again on the two valve seat portions 38 and 39.
[0022]
The pressure accumulating chamber 10 may be provided independently from the housing 1, but when provided integrally with the housing 1 as in the above embodiment, the surroundings of the housing 1 are simplified, Mountability to the vehicle is further improved.
[0023]
【The invention's effect】
As described above in detail, according to the pneumatic pressure booster according to the present invention, the surroundings of the housing are simplified, so that the mounting property to the vehicle is improved. A control circuit is not required, and the structure can be simplified and the cost can be reduced. In addition, since the high-pressure air passage is opened when a force greater than a predetermined force is applied to the input shaft, the passage is smoothly switched from the atmosphere side to the high-pressure air side, during high deceleration braking or suddenly A large braking force can be obtained with good timing during deceleration.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing the overall structure of a pneumatic booster according to the present invention.
FIG. 2 is a cross-sectional view showing a main structure of the atmospheric pressure booster.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Housing 5 Diaphragm 6 Power piston 7 Negative pressure chamber 8 Actuation pressure chamber 10 Accumulation chamber 11 High pressure air source 13 Valve body 17 Input shaft 20 Negative pressure passage 21 Ventilation passage 22 High pressure air passage 24 Plunger 27 Output shaft 28 Guide member 29 Actuation rod 31 Atmospheric passage 42 First valve mechanism 43 Second valve mechanism 46 Fixing pin (rod member)
47 On-off valve 49 Spring 52 Seat member (valve seat)
54 Ball (valve)

Claims (2)

The housing is partitioned into a negative pressure chamber and a working pressure chamber by a power piston having a diaphragm, a valve body having a negative pressure passage, an atmospheric passage and a high pressure air passage is attached to the power piston, and the thrust of the power piston is applied to the power piston. The valve body and the reaction disc are transmitted to the output shaft , and a part of the reaction force of the reaction disc is transmitted through the plunger operatively connected to the input shaft, and the operation is performed in the valve body. A first valve mechanism for switching the negative pressure passage and the atmospheric passage to the pressure chamber; and a second valve mechanism for switching the atmospheric passage and the high pressure air passage to the working pressure chamber. And the first and second valve mechanisms are operatively connected to an input shaft, and the first valve mechanism is adapted to move the atmosphere according to relative movement between the input shaft and the valve body. Open road, the second valve mechanism, when a predetermined force or more force to the input shaft is given, the rod member which is fixed to the plunger which transmits the reaction force from the reaction disc A pneumatic booster that opens relative to an input shaft to open the high-pressure air passage. The housing is partitioned into a negative pressure chamber and a working pressure chamber by a power piston having a diaphragm, a valve body having a negative pressure passage, an atmospheric passage and a high pressure air passage is attached to the power piston, and the thrust of the power piston is applied to the power piston. transmitted to the output shaft through the valve body and the reaction disc, and a portion of the reaction force of the reaction disc so as to transmit via a plunger which is operatively connected to the input shaft, the hollow shaft portion of the valve body In addition, a first valve mechanism that switches the negative pressure passage and the atmospheric passage to the working pressure chamber, and a second valve mechanism that switches the atmospheric passage and the high pressure air passage to the working pressure chamber. And the first and second valve mechanisms are operatively connected to the input shaft, and the first valve mechanism is responsive to relative movement between the input shaft and the valve body. An opening / closing valve interlocked with the input shaft, the opening / closing valve comprising: a valve seat formed in the middle of the high-pressure air passage; and a valve body constantly seated on the valve seat; And a rod member fixed to the plunger that transmits a reaction force from the reaction disk , and a spring that urges the open / close valve toward the input shaft by bringing one end into contact with the rod member. The input shaft and the rod member move relative to each other so as to open the high-pressure air passage by separating the valve body from the valve seat when a force greater than a predetermined force is applied to the input shaft. Pneumatic booster characterized by that.

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