JP2012232638A - Pneumatic booster - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic booster for eliminating a variation of the spring force of a valve spring of a poppet valve.SOLUTION: A brake pedal is used for operating an input rod 133 to move a plunger 131 relative to a valve body 111 so that a cup-shaped vacuum valve seal 159 and an atmospheric valve seal 172 interrupt the communication of a constant pressure chamber 107 (negative pressure) with a variable pressure chamber 108 to introduce atmosphere into the variable pressure chamber 108. With a differential pressure between the constant pressure chamber 107 and the variable pressure chamber 108, a power piston 106 generates thrust so that an output rod 128 pressurizes a master cylinder. The reaction of the master cylinder is feedback via a reaction member 154 to the input rod 133. Since the poppet valve is not used, there is no need for the valve spring to thrust a valve element to a valve seat to eliminate a variation of the spring force of the valve spring.

Description

  The present invention relates to a pneumatic booster mounted on a brake device of a vehicle such as an automobile.

  For example, in a pneumatic booster described in Patent Document 1, the inside of a housing is connected to a constant pressure chamber (connected to a negative pressure such as engine intake negative pressure by a power piston) and a variable pressure chamber. It is defined. A plunger connected to an input rod connected to the brake pedal is provided in the valve body connected to the power piston. The control valve that operates when the plunger moves moves between the constant pressure chamber and the variable pressure chamber to introduce the atmosphere (positive pressure) into the variable pressure chamber. Thus, a pressure difference is generated between the constant pressure chamber and the variable pressure chamber, and braking is performed by generating a brake fluid pressure in the master cylinder by a thrust generated in the power piston due to the pressure difference.

  The control valve is composed of a vacuum valve that opens and closes between the constant pressure chamber and the variable pressure chamber, and an atmospheric valve that communicates and blocks between the variable pressure chamber and the atmosphere. The valve is a poppet valve.

JP 2010-254219 A

  In the above-mentioned patent document 1, when the plunger opens the atmospheric valve, the input rod is compressed in addition to the return spring to compress the valve spring that urges the atmospheric valve to the closed position. The spring force of the valve spring acts. Due to the action of the spring force, the operation force of the input rod, that is, the required pedaling force of the brake pedal fluctuates, causing a problem that the operation feeling deteriorates.

  An object of the present invention is to provide a pneumatic booster that eliminates fluctuations in operating force.

  In order to solve the above problems, the present invention provides a housing, a power piston that defines a constant pressure chamber and a variable pressure chamber in the housing, a valve body connected to the power piston, and a movement to the valve body. A plunger inserted in a possible manner; an input rod connected to the plunger; an output rod connected to the valve body; a vacuum passage communicating the constant pressure chamber and the variable pressure chamber; and the constant pressure chamber to the atmosphere. An atmospheric passage that opens, closes the vacuum passage by the movement of the plunger relative to the valve body, shuts off the constant pressure chamber and the variable pressure chamber, opens the atmospheric passage and introduces the atmosphere into the variable pressure chamber, A pneumatic booster that propels the power piston by a differential pressure generated between the constant pressure chamber and the variable pressure chamber, wherein the plunger is inserted into the plunger. Is the sliding contact with the guide bore, a pair of cup-shaped sealing member for opening and closing the vacuum passage and the atmosphere passage, respectively, characterized in that it is provided with axially spaced from each other.

  According to the pneumatic booster according to the present invention, fluctuations in operating force can be eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram illustrating a schematic configuration of an automobile brake device including a pneumatic booster according to an embodiment of the present invention. 1 is a longitudinal sectional view of a pneumatic booster according to an embodiment of the present invention. FIG. 3 is an enlarged longitudinal sectional view showing a plunger portion as a main part when the pneumatic booster of FIG. 2 is not in operation. FIG. 3 is a longitudinal sectional view showing, in an enlarged manner, a control valve portion, which is a main portion when the pressure booster of FIG. 2 is pressurized. It is a longitudinal cross-sectional view which expands and shows the control valve part which is the principal part at the time of balance of the pneumatic pressure booster of FIG. It is a longitudinal cross-sectional view which expands and shows the control valve part which is the principal part at the time of pressure reduction of the pneumatic booster of FIG. It is a longitudinal cross-sectional view which expands and shows the atmospheric valve of the control valve of the pneumatic booster of FIG. It is a graph which shows the input-output characteristic of the pneumatic booster of FIG. It is a graph which shows the input-output hysteresis characteristic at the time of pressure increase of the booster of FIG. 2, and pressure reduction.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
A vehicle brake device 200 using a booster 101 according to the present embodiment will be described with reference to FIG. As shown in FIG. 1, a brake device 200 is connected to a booster 101 and hydraulic ports 164 and 165 of a master cylinder 110 of the booster 101, and a wheel cylinder of a hydraulic brake for each of the wheels Wa to Wd. A hydraulic pressure control device 5 that supplies brake hydraulic pressure to Ba to Bd, a controller 7 that controls the hydraulic pressure control device 5, and a regenerative brake device 8 that performs regenerative braking are provided.

  The hydraulic control device 5 supplies a first hydraulic circuit 5A (hydraulic pressure in FIG. 1) for supplying hydraulic pressure from the primary port 164 of the master cylinder 110 to the wheel cylinders Ba and Bb of the left front wheel Wa and the right rear wheel Wb. The second hydraulic circuit 5B (the liquid in FIG. 1) for supplying hydraulic pressure from the secondary port 165 to the wheel cylinders Bc and Bd of the right front wheel Wc and the left rear wheel Wd. 2 systems of hydraulic circuits, which are so-called “X pipes” composed of the pressure control device 5 and the left part from the center of the pressure control device 5. In this embodiment, the wheel cylinders Ba to Bd actuate a hydraulic disc brake that supplies hydraulic pressure to advance the piston and presses the brake pad against the disc rotor that rotates with the wheel to generate braking force. However, other hydraulic brakes such as a known drum brake may be operated.

  The first hydraulic circuit 5A and the second hydraulic circuit 5B have the same configuration, and the hydraulic circuits connected to the wheel cylinders Ba to Bd of the wheels Wa to Wd have the same configuration. In the following description, the subscripts A and B and a to d of the reference numerals indicate that they correspond to the first hydraulic circuit 5A and the second hydraulic circuit 5B and the wheels Wa to Wd, respectively. Yes.

  The hydraulic pressure control device 5 includes supply valves 35A and 35B that are electromagnetic on-off valves that control the supply of hydraulic pressure from the master cylinder 110 to the wheel cylinders Ba to Bd of the wheels Wa to Wd, and the wheel cylinder Ba. To the pressure increase valves 36a to 36d, which are electromagnetic on-off valves for controlling the supply of the hydraulic pressure to Bd, the system reservoirs 37A and 37B for releasing the hydraulic pressure from the wheel cylinders Ba to Bd, and the system from the wheel cylinders Ba to Bd Drives the pressure reducing valves 38a to 38d, which are solenoid valve on / off valves that control the release of the hydraulic pressure to the reservoirs 37A and 37B, and the pumps 39A and 39B and the pumps 39A and 39B to supply the hydraulic pressure to the wheel cylinders Ba to Bd. The pump motor 40 and the supply of hydraulic pressure from the master cylinder 110 to the suction side of the pumps 39A and 39B. Pressurizing valves 41A and 41B, which are electromagnetic on-off valves, check valves 42A, 42B, 43A, 43B, 44A and 44B for preventing backflow from the downstream side to the upstream side of the pumps 39A and 39B; Fluid pressure sensors 45A and 45B that detect fluid pressures of the primary port 164 and the secondary port 165 are provided.

Then, the controller 7 as a wheel pressure control unit controls the operation of the supply valves 35A and 35B, the pressure increasing valves 36a to 36d, the pressure reducing valves 38a to 38d, the pressure increasing valves 41A and 41B, and the pump motor 40, and the following operation is performed. The mode can be executed.
[Normal braking mode]
During normal braking, the supply valves 35A and 35B and the pressure increasing valves 36a to 36d are opened, and the pressure reducing valves 38a to 38d and the pressure increasing valves 41A and 41B are closed, so that the master cylinder 110 changes the wheel cylinders Ba to Bd. Supply hydraulic pressure.
[Decompression mode]
By opening the pressure reducing valves 38a to 38d and closing the supply valves 35A and 35B, the pressure increasing valves 36a to 36d and the pressure increasing valves 41A and 41B, the hydraulic pressures of the wheel cylinders Ba to Bd are released to the reservoirs 37A and 37B to reduce the pressure.
[Retention mode]
The hydraulic pressures of the wheel cylinders Ba to Bd are maintained by closing the pressure increasing valves 36a to 36d and the pressure reducing valves 38a to 38d.
[Pressure increase mode]
The pressure increasing valves 36a to 36d are opened, the supply valves 35A and 35B, the pressure reducing valves 38a to 38d and the pressure increasing valves 41A and 41B are closed, and the pump motor 40 is operated, whereby the brake fluid is supplied from the reservoirs 37A and 37B to the master cylinder 110 side. The hydraulic pressure of the wheel cylinders Ba to Bd is increased.
[Pressure mode]
By opening the pressurizing valves 41A and 41B and the pressure increasing valves 36a to 36d, closing the pressure reducing valves 38a to 38d and the supply valves 35A and 35B and operating the pump motor 40, the pump 39A can be operated regardless of the hydraulic pressure of the master cylinder 110. , 39B supply brake fluid to the wheel cylinders Ba to Bd.

  Various brake controls can be performed by appropriately executing these operation modes according to the vehicle state. For example, braking force distribution control that appropriately distributes the braking force to each wheel according to the ground load during braking, anti-lock brake control that automatically adjusts the braking force of each wheel during braking to prevent wheel locking, A vehicle that suppresses understeer and oversteer and stabilizes the behavior of the vehicle by detecting a side slip of a running wheel and automatically automatically applying a braking force to each wheel regardless of the operation amount of the brake pedal 19. Stability control, slope start assist control that keeps braking on hills (especially uphill) and assists in starting, traction control that prevents wheels from slipping when starting, etc., maintains constant distance from the preceding vehicle Vehicle follow-up control, lane departure avoidance control for holding a traveling lane, obstacle avoidance control for avoiding a collision with an obstacle, and the like can be executed.

  As the pumps 39A and 39B, for example, known hydraulic pumps such as a plunger pump, a trochoid pump, and a gear pump can be used. However, considering the on-board performance, quietness, pump efficiency, etc., it is desirable to use a gear pump. As the pump motor 40, a known motor such as a DC motor, a DC brushless motor, an AC motor, or the like can be used.

  Further, the characteristics of the electromagnetic on-off valve of the hydraulic pressure control device 5 can be appropriately set according to the use mode, but the supply valves 35A and 35B and the pressure increasing valves 36a to 36d are normally opened valves, and the pressure reducing valves 38a to 38d. Since the pressurizing valves 41A and 41B are normally closed valves, fluid pressure can be supplied from the master cylinder 110 to the wheel cylinders Ba to Bd when there is no control signal from the controller 7, so that fail-safe and control is possible. Such a configuration is desirable from the viewpoint of efficiency.

  The regenerative braking device 8 recovers kinetic energy as electric power by driving a generator (electric motor) by rotation of at least one wheel during deceleration and braking. In the brake device 200 of the present embodiment, the regenerative brake device 8 and the controller 7 exchange control signals with each other, and the regenerative braking amount is applied during regenerative braking in response to the operation of the brake pedal 19 by the driver. Regenerative cooperative control for obtaining a desired braking force is performed by supplying the brake fluid pressure with reduced to the wheel cylinders Ba to Bd.

  Next, the booster 101 will be described with reference to FIGS. FIG. 2 shows an overall configuration of the booster 101, and FIG. 3 shows an enlarged main part thereof. As shown in FIGS. 2 and 3, the booster 101 is a single-type pneumatic booster, in which a front shell 102 and a rear shell 103 formed by thin plates are combined to form a housing 104. Yes. The housing 104 is divided into two chambers, a constant pressure chamber 107 and a variable pressure chamber 108, by a power piston 106 having a diaphragm 105. The front shell 102 and the rear shell 103 are formed in a substantially bottomed cylindrical shape, and the opening edge of the outer periphery of the rear shell 103 is fitted to the opening edge of the outer periphery of the front shell 102, and the outer periphery of the diaphragm 105 is interposed therebetween. By being sandwiched, it is tightly coupled.

  The master cylinder 110 (see FIG. 1) is coupled to the front shell 102 by inserting a rear end portion into a central opening 109 at the bottom of the front shell 102. A rear cylindrical portion 112 for inserting a valve body 111, which will be described later, protrudes from a central portion of the bottom portion of the rear shell 103, and a rear portion that abuts a dash panel (not shown) of the vehicle body around the rear cylindrical portion 112. A seating surface 103A is formed.

  The housing 104 is provided with a tie rod 114 that penetrates from the front shell 102 to the rear seat surface 103A of the rear shell 103. The tie rod 114 has an attachment screw portion 115 and a fixing screw portion 116 formed at both ends, and a front flange 117 and a rear flange 118 that are enlarged in diameter are formed at the base portions of the attachment screw portion 115 and the fixing screw portion 116, respectively. . The front flange 117 is in airtight contact with the inner side of the front seat surface 102A via the retainer 119 and the seal 120, and the rear flange 118 is in airtight contact with the inner side of the rear seat surface 103A. It is fixed by caulking. An intermediate portion of the tie rod 114 is inserted into an opening 121 provided in the power piston 106 and a substantially cylindrical rod seal 122 formed integrally with the diaphragm 105, so that the power piston 106 and the diaphragm 105 can slide. Has penetrated.

  The tie rods 114 are arranged at two locations in the diametrical direction of the front shell 102 and the rear shell 103 (only one is shown). The master cylinder 110 is fixed to the front shell 102 by the mounting screw portion 115, and the rear seat is fixed by the fixing screw portion 116. The surface 103A is fixed to a dash panel (not shown) of the vehicle body. A rear bolt 123 for fixing the rear seat surface 103A to the dash panel is fixed by caulking.

  A substantially cylindrical valve body 111 is connected to the power piston 106 and the diaphragm 105. A front end portion of the valve body 111 is expanded to integrally form a large diameter portion 111A. The large diameter portion 111A is inserted into the central opening of the power piston 106 and the diaphragm 105, the inner peripheral edge of the central opening is fitted into the outer peripheral groove 11B of the large diameter portion 111A, and these are hermetically coupled. The rear side of the valve body 111 passes through the variable pressure chamber 108, is inserted into the rear cylindrical portion 112 of the rear shell 103, and the rear portion extends to the outside. A seal member 124 is attached to the rear cylindrical portion 112 so as to slidably seal with the valve body 111. Further, a bellows-shaped dust cover 125 is provided between the rear cylindrical portion 112 and the valve body 111. A connecting pipe 126 is attached to the front shell 102, and the connecting pipe 126 is connected to a negative pressure source (not shown) such as an intake pipe of the engine, so that the constant pressure chamber 107 is always maintained at a substantially predetermined negative pressure. .

  A cup-shaped holder 150 is attached to the distal end portion of the large-diameter portion 111A of the valve body 111. The holder 150 is integrally formed with a stepped flange-shaped spring receiving portion 151 on the outer periphery of the opening, and is fixed to the valve body 111 by fitting the spring receiving portion 151 to the distal end portion of the large-diameter portion 111A. . The holder 150 is disposed concentrically with the valve body 111 and has an opening 152 at the bottom. An annular reaction force receiving member 153 is fitted into the holder 150 and abuts the bottom, and a disc-shaped reaction member 154 made of an elastic body such as rubber is inserted to contact the reaction force receiving member 153. Touching. Further, a base end portion 128 </ b> A formed in a cup shape of the output rod 128 is slidably inserted into the holder 150, and a reaction member 154 is fitted into the base end portion 128 </ b> A, and the reaction force receiving member 153. The reaction member 154 is interposed between the output rod 128 and the output rod 128. The tip of the output rod 128 abuts on the primary piston 160 of the master cylinder 110 (see FIG. 1) inserted into the opening 109 of the front shell 102. The reaction force receiving member 153 is provided with a stepped opening, and a convex reaction force transmission member 155 is fitted and guided in the opening so as to be movable in the axial direction. The reaction force transmission member 155 has a large diameter portion at the front end facing the reaction member 154 with a predetermined gap C, and a small diameter portion at the rear end protruding from the opening 152 at the bottom of the holder 150.

  A plunger 131 is slidably guided along the axial direction in a small-diameter guide bore 156 formed at an intermediate portion in the valve body 111. A substantially cylindrical guide member 157 is fitted in the rear cylindrical portion of the valve body 111, and the guide member 157 has a step formed on the outer peripheral portion of the valve body 111. It is in contact with the part and is positioned in the axial direction. The valve body 111 and the guide member 157 are sealed with an O-ring 158. The plunger 131 has a vacuum valve seal 159 as a cup-shaped seal member attached to the outer periphery of a small diameter portion 131A formed at the front end portion. The vacuum valve seal 159 is fixed by a retaining ring 170 attached to the distal end portion of the small diameter portion 131A. The vacuum valve seal 159 is formed in a lip shape whose outer peripheral portion expands rearward, and the outer peripheral edge portion is in sliding contact with the inner peripheral surface of the guide bore 156 to seal between the plunger 131 and the guide bore 156. . The rear end side of the plunger 131 is inserted into the guide member 157, and an atmospheric valve seal 172, which is a cup-shaped seal member, is fitted and fixed to an outer peripheral groove 171 formed at the rear end portion. The atmospheric valve seal 172 is formed in a lip shape that expands toward the rear, and the outer peripheral edge is in sliding contact with the inner peripheral surface that serves as the guide bore of the guide member 157 to seal between the plunger 131 and the guide member 157. To do.

  The distal end portion of the input rod 133 inserted from the rear portion of the valve body 111 is inserted and connected to the plunger 131 so that the plunger 131 is operated by the input rod 133. The base end portion of the input rod 133 extends outside through a breathable dust seal 134 attached to the rear end portion of the valve body 111. A clevis 135 for connecting the brake pedal 19 (see FIG. 1) is attached to the base end portion of the input rod 133.

  An engagement groove 173, which is an outer peripheral groove, is formed in the intermediate portion of the plunger 131 in the axial direction, and an engagement passage 174 passes through the side wall of the valve body 111 so as to face the engagement groove 173. A stop key 138 is inserted into the engagement groove 173 and the engagement passage 174. The stop key 138 defines the retracted position of the valve body 111 by engaging with the stepped portion of the cylindrical portion 112 of the rear shell 103, and the relative position between the valve body 111 and the plunger 31 by engaging with the engaging groove 173. Specifies the amount of displacement.

  A return spring 139 is provided between the front wall of the front shell 102 and the spring receiving portion 151 of the holder 150 attached to the front end of the cylindrical portion 111A of the valve body 111 to urge the valve body 111 to the retracted position. Yes. A retainer 150 </ b> A that holds the output rod 128 is interposed between the return spring 139 and the spring receiving portion 151. Between the guide member 157 in the valve body 111 and the 133A flange portion of the input rod 133, a tapered return spring 140 that biases the input rod 133 to the retracted position is provided.

  A valve groove 175 extending along the axial direction is formed on the inner peripheral surface of the guide bore 156 of the valve body 111. A plurality of valve grooves 175 are arranged in the circumferential direction, extend from the vicinity of the front end portion of the guide bore 156 to the rear end portion, the cylindrical portion of the valve body 111 in which the guide member 157 is inserted, and the engagement passage 174 of the valve body 111. Communicating with The valve groove 175 constitutes a vacuum passage that communicates the constant pressure chamber 107 and the variable pressure chamber 108 via the engagement passage 174. At the side wall of the guide member 157, an air valve port 176 that constitutes an air passage for introducing air into the variable pressure chamber through the rear portion of the valve groove 175 and the engaging passage 174 is penetrated.

  When the plunger 131 is in the inoperative position shown in FIGS. 2 and 3, the vacuum valve seal 159 is disposed on the valve groove 175, opens the valve groove 175, and allows the pressure chamber 107 and the variable pressure chamber 108 to communicate with each other. The atmospheric valve seal 172 closes the atmospheric valve port 176 and shuts off the variable pressure chamber 108 from the atmosphere. At this time, the front end portion of the valve groove 175 and the lip-shaped outer peripheral edge portion of the vacuum valve seal 159 are separated by a distance S, and the lip-shaped outer peripheral edge portion of the atmospheric valve port 176 and the atmospheric valve seal 172 Is separated by a distance T. Here, the distance T is larger than the distance S (S <T), and is preferably about 0.2 to 1.0 mm larger than the distance S. Further, a gap L slightly larger than the distance T is provided between the front end portion of the plunger 131 and the rear end portion of the reaction force transmission member 155 (T <L).

  As a result, when the plunger 131 moves forward with respect to the valve body 111, first, the vacuum valve seal 159 crosses the front end of the valve groove 175, closes the vacuum passage formed by the valve groove 175, and the constant pressure chamber 107 is transformed. Communication with the chamber 108 is blocked. When the plunger 131 further advances, the atmospheric valve seal 172 opens the atmospheric valve port 176, and the variable pressure chamber 108 is opened to the atmosphere via the engagement passage 174, the valve groove 175, and the atmospheric valve port 176.

  In the present embodiment, the booster 101 is incorporated in the brake device 200 and executes regenerative cooperative control, which will be described later. Therefore, the distance T between the atmospheric valve seal 172 and the atmospheric valve port 176 in the inoperative position is sufficiently large. Is set.

Next, the operation of the booster 101 will be described with reference to FIGS.
2 and 3, the input rod 133 and the plunger 131 are in the illustrated retracted position, the vacuum valve seal 159 is on the valve groove 175, and the constant pressure chamber 107 and the variable pressure chamber 108 are communicated with each other. The In addition, the atmospheric valve seal 172 closes the atmospheric valve port 176 and blocks the variable pressure chamber 108 from the atmosphere. Accordingly, the constant pressure chamber 107 and the variable pressure chamber 108 have the same pressure (negative pressure), and thus no thrust is generated in the power piston 106. At this time, the lip-shaped outer peripheral edge of the vacuum valve seal 159 and the front end of the valve groove 175 are separated by a distance S, and the lip-shaped outer peripheral edge of the atmospheric valve seal 172 and the atmospheric valve port 176 are separated from each other. The reaction force transmission member 155 and the plunger 131 are separated from each other by a distance L.

  When the brake pedal 19 is depressed, first, the input rod 133 and the plunger 131 move forward with respect to the valve body 111 until these strokes X reach the distance S between the vacuum valve seal 159 and the front end of the valve groove 175. In this region, the communication state between the constant pressure chamber 107 and the variable pressure chamber 108 and the cutoff state between the variable pressure chamber 108 and the atmosphere are maintained. At this time, the input Fi (depressing force of the brake pedal 19) to the input rod 133 is a resultant force of the set load F1 of the return spring 140 and the force Fv (force in the direction in which the plunger 131 moves forward) due to the differential pressure acting on the plunger 131. Becomes larger (Fi> F1-Fv), the input rod 133 and the plunger 131 begin to move forward. FIG. 8 shows a point S1 where Fi = F1-Fv.

The input Fi to the input rod 132 is expressed by the following formula Fi = F1-Fv + K · X as the forward stroke X of the input rod 133 and the spring constant K of the return spring 140.
Can be expressed as

  As shown in FIG. 4, when the stroke X of the input rod 133 and the plunger 131 exceeds the distance T between the atmospheric valve seal 172 and the atmospheric valve port 176, the atmospheric air becomes the atmospheric valve port 176, the valve groove 175, and the engagement passage. 174 is introduced into the variable pressure chamber 108. FIG. 8 shows a point S2 where Fi = F1-Fv + K · T. In this way, the constant pressure chamber 107 and the variable pressure chamber 108 are shut off, and air is introduced into the variable pressure chamber 108, whereby a differential pressure is generated between the constant pressure chamber 107 and the variable pressure chamber 108, and thrust is applied to the power piston 106. Occurs, and the valve body 111 moves forward against the spring force of the return spring 139. The valve body 111 presses the primary piston 160 of the master cylinder 110 with the output rod 128 via the holder 152, the reaction force receiving member 153, and the reaction member 154. At this time, the tip of the plunger 131 abuts against the reaction force transmission member 155, and a part of the reaction force that acts on the reaction member 154 from the master cylinder 110 side via the reaction force transmission member 155, that is, the input rod 133 is fed back.

  After that, as shown in FIG. 5, the valve body 111 advances, the atmospheric valve seal 172 closes the atmospheric valve port 176, the variable pressure chamber 108 is shut off from the atmosphere, and the vacuum valve seal 159 closes the valve groove 175. When maintained, the differential pressure between the constant pressure chamber 107 and the variable pressure chamber 108 is maintained, and the thrust of the power piston 106 is also maintained constant. Thereby, when the depression amount of the brake pedal 19 is made constant, the thrust of the power piston 106, that is, the hydraulic pressure of the master cylinder 110 is kept constant.

  When the brake pedal 19 is released and the input to the input rod 133 is released, the plunger 131 and the input to the valve body 111 due to the reaction force from the reaction member 154 and the spring force of the return spring 140 as shown in FIG. The rod 133 is retracted, and the atmospheric valve seal 172 closes the atmospheric valve port 176 to block the variable pressure chamber 108 from the atmosphere. In addition, the vacuum valve seal 159 opens the valve groove 175 to connect the constant pressure chamber 107 and the variable pressure chamber 108, and the pressure difference between them is eliminated. As a result, the thrust of the power piston 106 disappears, and the power piston 106 and the valve body 111 are retracted by the spring force of the return spring 139 and returned to the inoperative position shown in FIG.

  The input / output characteristics of the booster 101 are shown in FIG. In FIG. 8, a curve A1 indicates the relationship between the stroke X of the input rod 133 (brake pedal 19) and the input Fi (depression force of the brake pedal 19), and a curve A2 indicates the stroke X of the input rod 133 and the master cylinder 110. The relationship between the hydraulic pressure P and the curve A3 indicates the relationship between the input Fi of the input rod 133 and the hydraulic pressure P of the master cylinder 110. A curved line A1 ′ represented by a broken line shows the relationship between the stroke of the input rod and the input (equal force of the brake pedal) of a conventional pneumatic booster using a poppet type vacuum valve and an atmospheric valve. Yes.

Next, control of the brake device 200 by the controller 7 will be described.
Referring to FIG. 8, in booster 101, stroke X of input rod 133 reaches distance T, atmospheric valve seal 172 opens atmospheric valve port 176, and thrust of power piston 106 is generated, and output rod 128 Until the primary piston 160 is moved forward and the reservoir port is closed (see distance M in FIG. 8), no hydraulic pressure is generated in the master cylinder 110. During an invalid stroke (distance T + M in FIG. 8) in which no hydraulic pressure is generated in the master cylinder 110 in response to the operation of the brake pedal 19, the controller 7 detects the input rod 133 (that is, the brake pedal 19) detected by the stroke sensor 20. Regenerative braking is performed by the regenerative braking device 8 based on the stroke of the regenerative braking, and the hydraulic pressure control device 5 reduces the regenerative braking amount and supplies the brake hydraulic pressure to the wheel cylinders Ba to Bd to obtain a desired braking force. Execute control.

  After the hydraulic pressure is generated in the master cylinder 110, the hydraulic pressure corresponding to the hydraulic pressure generated in the master cylinder 110 is reduced from the supplied hydraulic pressure by the hydraulic pressure control device 5 until a predetermined stroke S3. Then, after the stroke X of the input rod 133 reaches the predetermined stroke S3, the booster 101 generates the total hydraulic pressure supplied to the wheel cylinders Ba to Bd. The hydraulic pressure of the master cylinder 110 corresponding to the braking amount by the regenerative cooperative control is indicated by the hatched portion in FIG. Until the plunger 131 comes into contact with the reaction member 155 with respect to the stroke of the input rod 133, only the reaction force of the spring force of the return spring 140 acts mainly, so that a good operation feeling of the brake pedal 19 is obtained. Can do.

  Until the stroke X of the input rod 133 reaches a predetermined stroke (distance T + M), no hydraulic pressure is generated in the master cylinder 110, so that regenerative braking can be utilized to the maximum and energy can be efficiently recovered. . Further, the reaction force of the hydraulic pressure of the master cylinder 110 does not act on the input rod 133 until the plunger 131 comes into contact with the reaction member 155 due to the stroke of the input rod 133. Even when the hydraulic pressure at 110 is fluctuated, the brake pedal 19 is not affected by kickback due to the reaction force of the hydraulic pressure, and a good operation feeling can be obtained.

  By sliding the cup-shaped vacuum valve seal 159 in the guide bore 156, the valve groove 175 is opened and closed to communicate and block between the constant pressure chamber 107 and the variable pressure chamber 108, and the cup-shaped atmosphere in the guide member 157 The atmospheric valve port 176 is opened and closed by sliding the valve seal 172 so that the variable pressure chamber 108 and the atmosphere are communicated and shut off. Therefore, the response and the opening and closing are compared with the conventional poppet type vacuum valve and atmospheric valve. A degree of freedom in setting the valve timing can be provided. The vacuum valve seal 159 and the atmospheric valve seal 172 have a low sliding resistance because the sliding portion is formed in a lip shape. The movement of the plunger 131 is less affected by the pressure difference between the constant pressure chamber 107, the variable pressure chamber 108 and the atmosphere, and only the reaction force from the reaction member 155 and the spring force of the return spring 140 act mainly. The change b (hysteresis) of the input / output characteristics between when the brake pedal 19 is depressed and when the brake pedal 19 is released as shown in FIG. 9 can be reduced, and a good operation feeling can be obtained. Moreover, since the sliding part of the vacuum valve seal 159 and the atmospheric valve seal 172 is formed in a lip shape, the timing accuracy of the on-off valve can be increased. In FIG. 9, the input represents the depression force of the brake pedal 19, and the output represents the thrust of the output rod 128.

  The case of the atmospheric valve seal 172 will be described with reference to FIG. 7 as an example. Between the valve closed state shown in FIG. 7A and the valve opened state shown in FIG. The valve opening amount a of the atmospheric valve port 176 can be sufficiently increased with respect to the movement amount in the direction, and the variation in the valve opening amount a is reduced.

  DESCRIPTION OF SYMBOLS 101 ... Booster (pneumatic booster), 104 ... Housing, 106 ... Power piston, 107 ... Constant pressure chamber, 108 ... Transformer chamber, 111 ... Valve body, 128 ... Output rod, 131 ... Plunger, 133 ... Input rod 156 ... guide bore, 157 ... guide member (guide bore), 159 ... vacuum valve seal (seal member), 172 ... atmospheric valve seal (seal member), 175 ... valve groove (vacuum passage), 176 ... atmospheric valve port ( Atmospheric passage)

Claims (1)

A housing, a power piston that defines a constant pressure chamber and a variable pressure chamber in the housing, a valve body coupled to the power piston, a plunger movably inserted in the valve body, and coupled to the plunger An input rod, an output rod connected to the valve body, a vacuum passage communicating the constant pressure chamber and the variable pressure chamber, and an air passage opening the constant pressure chamber to the atmosphere, Due to the movement of the plunger, the vacuum passage is closed to shut off the constant pressure chamber and the variable pressure chamber, the atmospheric passage is opened to introduce the atmosphere into the variable pressure chamber, and the difference generated between the constant pressure chamber and the variable pressure chamber A pneumatic booster that propels the power piston by pressure,
The plunger is provided with a pair of cup-shaped seal members which are in sliding contact with a guide bore into which the plunger is inserted and which respectively open and close the vacuum passage and the atmospheric passage, and are separated from each other in the axial direction. Pneumatic booster.

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