JP3951483B2 - Brake system - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a brake system including a booster, and more particularly to a reaction force mechanism of a booster.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a brake system used in an automobile or the like generally includes a booster having an input shaft that is linked to a brake pedal, a master cylinder that is linked to an output shaft of the booster, and a wheel that is operated by the output hydraulic pressure of the master cylinder And a cylinder.
As the booster, a pneumatic booster and a hydraulic booster are used. The pneumatic booster includes a valve body slidably provided in a shell and a power piston provided on the valve body. A constant pressure chamber and a variable pressure chamber formed before and after the power piston, a valve mechanism provided in the valve body for controlling switching of the flow path, and slidably provided in the valve body. A valve plunger constituting the unit, an input shaft for moving the valve plunger forward and backward to switch the flow path of the valve mechanism, and an output shaft advanced by the advance of the power piston.
The reaction force mechanism of the pneumatic booster includes a rubber reaction disk disposed between the output shaft and the valve plunger. When the brake booster is activated, the reaction disk includes a valve body and a valve plunger. At the same time, a part of the brake reaction force applied to the output shaft is received by the valve body and the rest is transmitted to the valve plunger, and the brake reaction force applied to the valve plunger is transmitted to the driver via the input shaft and the brake pedal. It is made to perceive.
At this time, the servo ratio of the brake booster can be changed by changing the ratio between the reaction force received by the valve body and the reaction force received by the valve plunger, more specifically, the ratio of the pressure receiving area of both. .
On the other hand, the hydraulic booster is provided with a power piston slidably provided in a housing, a power chamber formed at one end of the power piston in the housing, and provided in the power piston and interlocking with an input shaft. A valve mechanism that is operated to switch the flow path, a supply passage that communicates the power chamber and the pressure fluid source via the valve mechanism, a discharge passage that communicates the power chamber to the reservoir via the valve mechanism, And an output shaft that is advanced by the advance of the power piston.
In this hydraulic booster, the hydraulic pressure in the power chamber is applied to the input shaft so that it can be transmitted to the driver as a brake reaction force.
[0003]
[Problems to be solved by the invention]
The servo ratio of the conventional booster is generally set to be large so that a large brake fluid pressure can be generated with a small brake pedal force, but it is expected to be large due to the delay of the brake booster during sudden braking. The output was not obtained, and it was found that it was difficult for a powerless driver such as an elderly person or a woman to perform sudden braking.
For example, in the case of a pneumatic booster, when the brake pedal is depressed, the flow path of the valve mechanism is switched via the input shaft, whereby pressure fluid is introduced into the variable pressure chamber and the power piston and valve body are advanced. It becomes like this. When the valve body moves forward, the output shaft is moved forward via the reaction disk. When the brake fluid pressure is generated by the advancement of the output shaft and the reaction force is applied to the output shaft, the brake reaction force applied to the output shaft as described above. Is distributed to the valve body and the valve plunger.
However, during sudden braking, before the power piston and valve body are advanced by the pressure fluid introduced into the variable pressure chamber, the valve plunger that is linked to the brake pedal via the input shaft is advanced, so that it is added to the output shaft. Most of the brake reaction force is transmitted to the valve plunger, and as a result, the brake reaction force transmitted to the driver is abnormally large.
As a result, when braking suddenly, you must overcome the abnormally large brake reaction force and depress the brake pedal, and in the case of normal brake operation that gradually depresses the brake pedal and obtains a large braking force Compared with, the brake force required for sudden braking could not be obtained unless the brake pedal was depressed with much greater force.
The same applies to the hydraulic booster.
In view of such circumstances, the present invention provides a brake system that can obtain a large output with a light pedal force during sudden braking.
[0004]
[Means for Solving the Problems]
  That is, the present invention described in claim 1 includes a pneumatic booster having an input shaft interlocked with a brake pedal, a master cylinder interlocked with an output shaft of the booster, and an output hydraulic pressure of the master cylinder. The pneumatic booster includes a valve body slidably provided in a shell, a power piston provided on the valve body, a constant pressure chamber and a variable pressure chamber formed before and after the power piston. A valve mechanism provided in the valve body for switching and controlling the flow path, a valve plunger slidably provided in the valve body and constituting a part of the valve mechanism, and advancing and retracting the valve plunger. A brake system having an input shaft for switching the flow path of the valve mechanism and an output shaft advanced by the advance of the power piston
  A fluid pressure reaction force mechanism for providing a pseudo reaction force to the valve plunger is provided while the reaction force applied to the output shaft is not transmitted to the valve plunger when the booster is operated. The mechanism is provided slidably on the valve body and has a reaction force piston on which the pressure of the constant pressure chamber and the variable pressure chamber acts, and a differential pressure between the pressure of the constant pressure chamber acting on the reaction force piston and the pressure of the variable pressure chamber The reaction force reducing means for reducing the reaction force transmitted from the fluid pressure reaction force mechanism to the valve plunger when the booster is suddenly operated is transmitted to the valve plunger as a pseudo reaction force. It is provided.
  According to a seventh aspect of the present invention, there is provided a hydraulic booster having an input shaft interlocked with a brake pedal, a master cylinder interlocked with an output shaft of the booster, and an output hydraulic pressure of the master cylinder. An operating wheel cylinder,
  The hydraulic booster is provided with a power piston slidably provided in a housing, a power chamber formed at one end of the power piston in the housing, and provided in the power piston and operating in conjunction with an input shaft. A valve mechanism that switches the flow path, a supply passage that communicates the power chamber and the pressure fluid source via the valve mechanism, a discharge passage that communicates the power chamber with the reservoir via the valve mechanism, and An output shaft that is advanced by the advance of the power pistonWhen the brake pedal is depressed and the hydraulic booster is activated, the hydraulic pressure in the power chamber is transmitted to the input shaft as a reaction force.In the brake system,
  In addition to the hydraulic pressure in the power chamber, a fluid pressure reaction force mechanism capable of transmitting a reaction force to the input shaft is provided, and the hydraulic typeReaction force reducing means is provided to reduce the reaction force transmitted from the fluid pressure reaction force mechanism to the input shaft during sudden operation of the booster.In the normal braking operation in which the brake pedal is gently depressed, the hydraulic pressure of the power chamber and the reaction force of the fluid pressure reaction force mechanism are transmitted to the input shaft as a brake reaction force, and the brake When the pedal is suddenly depressed, the reaction force transmitted from the fluid pressure reaction force mechanism to the input shaft is reduced by the reaction force reduction mechanism.
[0005]
[Action]
  According to the configuration of claim 1 aboveIn the normal operation, the reaction force is transmitted from the fluid pressure reaction force mechanism to the input shaft, so that the same operation as the conventional one can be performed. On the other hand, since the reaction force reducing means reduces the reaction force transmitted to the input shaft during sudden operation, it is possible to cause the booster device to perform sudden operation with a lighter operating force than during normal operation.
  Further, according to the configuration of the seventh aspect, during normal brake operation, the reaction force is transmitted from the power chamber and the fluid pressure reaction force mechanism to the input shaft, and the same operation as the conventional one can be performed. On the other hand, when the brake pedal is suddenly depressed, the reaction force from the fluid pressure reaction mechanism is reduced by the reaction force reducing means, so that the booster operates quickly with a lighter operating force than during normal operation. Can be performed.
[0006]
【Example】
The pneumatic booster of the present invention will be described below with reference to the illustrated embodiment. In FIG. 1, a valve body 3 is slidably provided in a front shell 1 and a rear shell 2 of the pneumatic booster.
The valve body 3 of the present embodiment is fitted in an input side member 4 that is air-tightly slidably provided in the cylindrical portion 2A of the rear shell 2 and a front side end portion of the input side member 4 so as to be relatively displaceable. And a combined output side member 5.
The input side member 4 is fitted and fixed to a cylindrical member 6 slidably inserted into the cylindrical portion 2A of the rear shell 2 and an outer peripheral surface of a front side end portion of the cylindrical member 6, A substantially U-shaped outer member 7 whose side end is open and a cylindrical inner member 8 fitted and fixed to the inner peripheral surface of the front end of the cylindrical member 6 are configured.
On the other hand, the output side member 5 is arranged on the rear side, and is connected to the front side of the rear side member 10 and has a bottomed side which is open on the rear side. It comprises a cylindrical front side member 11.
The rear side member 10 of the output side member 5 is slidably fitted to the outer side member 7 of the input side member 4 from the opening front side. And the retainer 12 attached to the rear side member 10 can be slid. Further, springs 13A and 13B as elastic members provided concentrically are mounted between the rear side member 10 and the outer member 7, and the output side member 5 and the input side member are supported by the springs 13A and 13B. 4 are biased in a direction away from each other in the axial direction.
A power piston 14 and a diaphragm 15 attached to the rear side of the power piston 14 are connected to the outer peripheral portion of the output side member 5, and the inside of the sealed container is connected to the constant pressure chamber A on the front side by the diaphragm 15. It is divided into a rear variable room B.
[0007]
Next, the valve mechanism 17 for switching the fluid circuit between the constant pressure chamber A and the variable pressure chamber B will be described. The valve mechanism 17 includes an annular first valve seat 18 formed on the tubular member 6 of the input side member 4 and an annular formed on the right end of a valve plunger 19 slidably fitted in the tubular member 6. The second valve seat 20 and a valve body 22 seated on the valve seats 18 and 20 by a poppet return spring 21 from the right side of FIG.
Then, the outer peripheral side of the first valve seat 18 is communicated with the constant pressure chamber A via the shaft portion of the cylindrical member 6 and the constant pressure passage 23 formed between the outer member 7 and the inner member 8, and this constant pressure. The chamber A is communicated with an intake manifold of an engine (not shown) through a negative pressure introduction pipe 24 that is connected to the front shell 1 to constantly introduce negative pressure. An intermediate portion between the first valve seat 18 and the second valve seat 20 is communicated with the variable pressure chamber B through a radial variable pressure passage 25 formed in the tubular member 6. Further, the inner peripheral side of the second valve seat 20 is communicated with the atmosphere through a pressure passage 26 formed in the input side member 4.
[0008]
The distal end of the input shaft 30 is pivotally connected to the right end of the valve plunger 19 slidably provided in the input side member 4 of the valve body 3. The input shaft 30 and the input side member 4 of the valve body 3 A spring 31 having a spring force larger than the spring force of the poppet return spring 21 is mounted. When the brake pedal is not depressed by the spring force of the spring 31, the valve plunger is not operated. The valve body 22 is seated on the 19 second valve seats 20, and the valve body 22 is separated from the first valve seat 18 of the input side member 4. The end portion of the input shaft 30 is interlocked with a brake pedal (not shown).
Further, the valve plunger 19 prevents the key member 32 from being pulled out from the cylindrical member 6 of the input side member 4. Although not shown, the key member 32 is formed in a bifurcated shape from the center to the tip, and the key member 32 is inserted into an insertion hole 33 (see FIG. 2) formed in the diameter direction of the cylindrical member 6. The base portion of the bifurcated portion is engaged with the small diameter portion 19a (see FIG. 2) of the valve plunger 19.
At this time, the insertion hole 33 and the variable pressure passage 25 are integrally formed adjacent to each other in the axial direction of the input side member 4, but are orthogonal to the width of the insertion hole 33, that is, the axial direction of the input side member 4. The width of the key member 32 in the direction perpendicular to the insertion direction of the insertion hole 33 is set wider than the width of the variable pressure passage 25 in the same direction. The member 4 can be displaced in the axial direction.
The key member 32 and the valve plunger 19 can be displaced in the axial direction with respect to the key member 32 within the range of the axial length of the small-diameter portion 19a, so that when the brake booster is not operated. The input side member 4 and the valve plunger 19 are brought into contact with the key member 32 in contact with the inner surface of the rear shell 2 and stopped. In this state, the valve plunger 19 is held at a position relatively advanced with respect to the valve body 3, thereby reducing the loss stroke of the input shaft 30 at the start of operation of the brake booster. Yes.
When the brake booster is not in operation, the springs 13A and 13B are compressed by the return spring 34 elastically placed between the inner wall of the front shell 1 and the front side member 11 of the output side member 5 to compress the input side member 4. The rear side member 10 of the output side member 5 is held in contact with the outer member 7 in the non-operating position in the figure.
[0009]
Next, the distal end portion of the output shaft 35 of the present embodiment is protruded to the outside from the shaft portion of the front shell 1 through the seal member 36, and is interlocked with a piston of a master cylinder (not shown). On the other hand, the base portion 35 </ b> A of the output shaft 35 is fitted into the concave portion 11 </ b> A formed in the front side member 11 of the output side member 5 and is integrally connected to the output side member 5.
Thus, in this embodiment, when the brake booster is operated, all the brake reaction force acting on the output shaft 35 via the master cylinder is received by the output side member 5 of the valve body 3 and is received by the valve plunger 19. It is not transmitted.
By the way, if the brake reaction force is not transmitted to the valve plunger 19, the driver cannot obtain a feeling of brake operation.
For this reason, in this embodiment, by providing the fluid pressure reaction force mechanism 37, a pseudo reaction force corresponding to the depression amount of the brake pedal is applied to the driver.
That is, the fluid pressure reaction force mechanism 37 includes a reaction force piston 38 slidably fitted to a support portion 11B protruding from the shaft portion of the front side member 11 of the output side member 5 to the rear side, and this reaction force. A second constant pressure chamber 39 formed in the front side member 11 on the rear side of the piston 38 and a second variable pressure chamber 40 formed in the front side member 11 on the front side of the reaction force piston 38 are provided. .
The second constant pressure chamber 39 communicates with the constant pressure chamber A through a communication hole 41 formed at the rear end of the front side member 11 and also communicates with the constant pressure passage 23.
On the other hand, the second variable pressure chamber 40 communicates with the variable pressure passage 25 via an orifice passage 43 as a reaction force reducing means 42 described in detail later, and communicates with the variable pressure chamber B via the variable pressure passage 25. In addition, the constant pressure chamber A is communicated with the constant pressure passage 23.
A protruding portion 38A that protrudes rearward from the shaft portion of the reaction force piston 38 is slidably fitted in the inner member 8 of the input side member 4 while maintaining airtightness. Is opposed to the large-diameter portion 19b of the valve plunger 19 fitted from the front side.
A spring 44 is elastically mounted between the reaction force piston 38 and the inner member 8 of the input side member 4, and this spring 44 allows the reaction force piston 38 to be connected to the output side member 5 when the brake booster is not operated. The front side member 11 is held in contact with the forward end position. In this state, a gap is formed between the protrusion 38 </ b> A of the reaction force piston 38 and the valve plunger 19.
A ring-shaped seal member 45 is disposed on the outer periphery of the reaction force piston 38, and the seal member 45 seals between the reaction force piston 38 and the front side member 11.
[0010]
Next, the configuration of the orifice passage 43 that reduces the reaction force transmitted from the fluid pressure reaction force mechanism 37 when the brake pedal is depressed relatively quickly will be described.
The orifice passage 43 is formed between the inner peripheral surface of the inner member 8 of the input side member 4 and the outer peripheral surface of the large-diameter portion 19b of the valve plunger 19 inserted into the inner member 8 from the front side. A first passage 46 that communicates with the passage 25, a second passage 47 that is formed in a projecting portion 38 </ b> A that projects from the shaft portion of the reaction force piston 38 to the rear side, communicates with the first passage 46, and the output A plurality of third passages 48 are formed on the outer peripheral surface of the support shaft 11B of the front side member 11 of the side member 5 and communicated with the second passage 47 and the second variable pressure chamber 40. This orifice passage 43, that is, the flow passage area of the second passage 47 formed in the protruding portion 38A of the reaction force piston 38 is set smaller than the flow passage area of the variable pressure passage 25.
The second passage 47 is opened in a groove 49 formed in the distal end surface of the projecting portion 38A of the reaction force piston 38 in the radially outward direction, so that the projecting portion 38A has a large diameter of the valve plunger 19. The first passage 46 and the second passage 47 can be communicated with each other through the groove 49 even when contacting the portion 19b.
[0011]
Further, in the present embodiment, the large diameter of the valve plunger 19 inserted into the orifice passage 43 in order to prevent the reaction force from being transmitted from the fluid pressure reaction force mechanism 37 when the brake pedal is depressed suddenly. A ring-shaped seal member 51 protruding outward in the radial direction is provided on the portion 19b.
The seal member 51 is positioned within a range of a stepped surface 52 (see FIG. 2) formed on the inner peripheral surface of the inner member 8 constituting a part of the orifice passage 43 during non-operation or normal operation. In this state, the variable pressure passage 25 and the second variable pressure chamber 40 are communicated with each other via the seal member 51 and the concave portion of the stepped surface 52.
On the other hand, as shown in FIG. 2, when the valve plunger 19 is positioned at the forward end position with respect to the input side member 4, the seal member 51 escapes from the stepped surface 52 and is formed on the front side. In this state, the seal member 51 is in close contact with the smooth surface 53 so that the orifice passage 43 is completely closed.
As can be understood from this, when the brake pedal is suddenly depressed, the valve plunger 19 is positioned at the forward end position with respect to the input side member 4, so that the seal member 51 is disposed on the inner member. 8 is in close contact with the smooth surface 53 and the communication between the variable pressure passage 25 and the second variable pressure chamber 40 is blocked.
Further, as shown in FIG. 3, the seal member 51 is in close contact with the smooth surface 53 because the valve plunger 19 is located at the forward end position with respect to the input side member 4 even when the brake booster is fully loaded. Thus, the orifice passage 43 is closed.
In this embodiment, the stepped surface 52 and the smooth surface 53 are formed on the inner member 8. However, the present invention is not limited to this. For example, a portion corresponding to the stepped surface 52 of the inner member 8 is sealed. A large diameter portion larger than the member 51 may be used, and a portion corresponding to the smooth surface 53 may be a small diameter portion smaller than the seal member 51.
[0012]
In this embodiment, a stroke shortening means 60 is provided for shortening the amount of operation of the brake pedal during a sudden operation as compared with that during a normal operation.
The stroke shortening means 60 is connected to an opening 61 formed in the rear shell 2 to connect the variable pressure chamber B to the atmosphere, an opening / closing valve 63 for opening and closing the conduit 62, and when not operating and during normal operation. A control device 64 that closes the on-off valve 63 to prevent air from being introduced into the variable pressure chamber B, and opens the on-off valve 63 to introduce air into the variable pressure chamber B when it is determined to be suddenly operated; I have.
A detection value is input to the control device 64 from a sensor (not shown) that detects a pedaling force or a stroke speed acting on the brake pedal, and the control device 64 receives the detection value and a preset reference value. When the detected value exceeds the reference value, it is determined that the brake is suddenly braked, and the on-off valve 63 is opened.
In this embodiment, the reference value of the control device 64 is set so that the on-off valve 63 is opened when the valve plunger 19 is stepped on at a stretch to the forward end position with respect to the valve body 3.
[0013]
The operation of the pneumatic booster having the above-described configuration will be described.
First, when the brake pedal is depressed relatively slowly from the non-operating state described above, the valve body 22 is seated on the first valve seat 18 formed on the input side member 4 as shown in FIG. The communication between the constant pressure passage 23 and the variable pressure passage 25 that have been in communication is blocked, and the valve body 22 is separated from the second valve seat 20 formed in the valve plunger 19 so that the variable pressure passage 25 and the pressure passage 26 are communicated. As a result, the atmosphere is introduced into the variable pressure chamber B through the variable pressure passage 25, so that a differential pressure is generated between the constant pressure chamber A and the variable pressure chamber B. The differential pressure causes the output side member 5 and the power piston 14 of the valve body 3 to It will move forward as one.
On the other hand, the advance amount of the input side member 4 is relatively smaller than the advance amounts of the output side member 5 and the power piston 14.
That is, a negative pressure acts on a portion of the input side member 4 located in the variable pressure chamber B, and air acts on a portion protruding outside the variable pressure chamber B. As a result, immediately after the valve mechanism 17 is switched, a differential pressure larger than the set load of the springs 13A and 13B is acting on the input side member 4, so that the input side member 4 contacts the output side member 5. Although it moves forward integrally, the differential pressure eventually decreases with a decrease in the negative pressure in the variable pressure chamber B. Therefore, when the differential pressure falls below the set load of the springs 13A and 13B, the input side member 4 becomes the output side member 5. Gradually move away from.
As understood from this, in this embodiment, the advance amount of the input side member 4 that accommodates the valve mechanism 17 is set smaller than the advance amount of the output side member 5. Accordingly, the stroke of the input shaft 30 and the brake pedal interlocked therewith can be made relatively small, so that the output side member 5 and the input side member 4 are fixed and the output side member 5 and the input side member are fixed. The brake feeling can be improved as compared with the case where the amount of forward movement 4 is the same.
In addition, since air is introduced into the second variable pressure chamber 40 formed on the front side of the reaction force piston 38 via the orifice passage 43, a differential pressure is generated between the second variable pressure chamber 40 and the second constant pressure chamber 39, The reaction force piston 38 is urged to the rear side by the differential pressure.
As a result, the reaction force piston 38 compresses and retracts the spring 44, and the projecting portion 38A contacts the end surface of the large diameter portion 19b of the valve plunger 19, so that the differential pressure acting on the reaction force piston 38 is reduced. Since it is transmitted to the brake pedal via the plunger 19 and the input shaft 30, the driver can sense the operational feeling of the brake.
By the way, when the brake pedal is continuously depressed gently and the booster is in a full load state, the input side member 4 is a position where the input side member 4 and the springs 13A and 13B are balanced as shown in the figure. And is stopped on the near side of the retainer 12.
Note that the timing and speed at which the input side member 4 is separated from the output side member 5 can be adjusted by the set load and spring constant of the springs 13A and 13B.
[0014]
Next, the operation when the brake pedal is depressed a little faster than the above-described gentle operation will be described. During such operation, the valve plunger 19 that is linked to the brake pedal via the input shaft 30 is normally depressed. Rather than the input side member 4.
As a result, the valve body 22 is separated from the second valve seat 20 formed on the valve plunger 19 more gently than when the valve body 22 is gently operated, so that a large amount of air is introduced into the variable pressure chamber B via the variable pressure passage 25. Thus, the output side member 5 and the power piston 14 of the valve body 3 are moved forward relatively quickly.
On the other hand, since only the same amount of air as that during the gentle operation is introduced into the second variable pressure chamber 40 on the front side of the reaction force piston 38 through the orifice passage 43, the reaction force against the increase in output described above. Will rise later.
As a result, the reaction force applied to the brake pedal by the fluid pressure reaction force mechanism 37 is relatively small when the operation speed of the brake pedal is high, compared with a gentle operation, so that the brake booster can be operated with a small force. Can be operated.
[0015]
Next, the operation when the brake pedal is suddenly operated will be described. During such a sudden operation, as shown in FIG. 2, the valve plunger 19 interlocked with the brake pedal is advanced at a stretch to the advance end position with respect to the input side member 4 via the input shaft 30.
As a result, the valve element 22 is greatly separated from the second valve seat 20 formed on the valve plunger 19, so that a large amount of air is introduced into the variable pressure chamber B via the variable pressure passage 25, and the stroke is shortened in synchronization therewith. The control device 64 of the means 60 determines that sudden braking is performed, and the open / close valve 63 that has been closed is opened, and air is separately introduced into the variable pressure chamber B from the conduit 62.
As a result, the differential pressure acting on the output side member 5 and the power piston 14 rapidly increases, so that the output side member 5 and the power piston 14 are rapidly advanced to perform rapid braking.
At this time, the differential pressure acting on the input side member 4 is rapidly reduced by the atmosphere introduced from the conduit 62 in addition to the atmosphere introduced from the valve mechanism 17. It will be separated at a point earlier than normal operation.
As a result, the amount of depression by which the driver depresses the brake pedal is shortened by the amount that the position where the input side member 4 is separated from the output side member 5 is on the near side. It can be made smaller than during normal operation. As a result, the response of the pneumatic booster can be improved and the braking distance can be shortened during sudden operation.
Further, the atmosphere is introduced into the second variable pressure chamber 40 on the front side of the reaction force piston 38 so far through the orifice passage 43, more specifically, between the seal member 51 and the stepped surface 52. However, during such a rapid operation, the seal member 51 is in close contact with the smooth surface 53 beyond the stepped surface 52 and immediately closes the orifice passage 43, so that a slight amount of air is introduced into the second variable pressure chamber 40. Become so. As a result, the reaction force piston 38 is urged to the rear side by a small differential pressure and comes into contact with the valve plunger 19.
As a result, the reaction force applied to the brake pedal by the fluid pressure reaction force mechanism 37 becomes very small during a sudden operation in which the valve plunger 19 is advanced to the forward end position with respect to the valve body 3. During operation, the brake booster can be suddenly operated with a lighter pedaling force than during normal operation.
[0016]
In this embodiment, as described above, the valve body 3 is composed of the input side member 4 and the output side member 5 so that the advance amount of the input side member 4 is relatively smaller than the advance amount of the output side member 5. Therefore, when the brake booster is stepped on from the full load state and the brake pedal is stepped on to obtain a larger braking force, the input side member 4 is connected to the relatively advanced output side member 5. Until the contact occurs, a non-reactive section occurs in which the output and reaction force do not increase even when the brake pedal is depressed.
However, in this embodiment, when the full load state is reached, the seal member 51 provided on the valve plunger 19 is in close contact with the smooth surface 53 of the inner member 8 to close the orifice passage 43 as described above. Since the output side member 5 can be moved forward in conjunction with the input side member 4 by the atmosphere in the space sealed by the passage 43, the second variable pressure chamber 40 and the seal member 51, the above-described non-reactive section is eliminated. Can do.
[0017]
Next, FIG. 4 shows a second embodiment of the present invention.
In the first embodiment, the orifice passage 43 is completely closed by the seal member 51 when the valve plunger 19 is rapidly moved to the forward end position of the valve body 3 at a stroke. In the example, the flow passage area in the orifice passage 143 is reduced during normal operation by the restriction portion 155 formed in the inner member 108 of the valve body 103 and the restriction portion 156 formed in the rear side portion of the large diameter portion 119b of the valve plunger 119. The effect close to that of the first embodiment can be obtained by narrowing down to a smaller value.
That is, the throttle portion 155 on the valve body 103 side is formed at an intermediate position in the inner member 108 that forms the first passage 146 of the orifice passage 143, and the protruding portion 138 A of the reaction force piston 138 slides on the front side thereof. A small-diameter portion 157 to be movably fitted is formed, and a large-diameter portion 158 having a larger diameter is formed on the rear side, and the small-diameter portion 157 substantially corresponds to the throttle portion 155. It is.
On the other hand, the throttle portion 156 on the valve plunger 119 side is formed to protrude radially outward from the rear side portion of the large diameter portion 119b of the valve plunger 119 forming the first passage 146 of the orifice passage 143. The outer diameter is formed to be slightly smaller than the narrowed portion 155 (small diameter portion 157).
The throttle portion 156 is positioned in the large diameter portion 158 when the brake pedal is not depressed or during normal operation. At this time, the second passage 147 formed in the reaction force piston 138 is provided. The flow path area of the first passage 146 is larger than that.
On the other hand, when the valve plunger 119 is stepped on suddenly such that the valve plunger 119 is positioned at the forward end position with respect to the valve body 103, the throttle portion 152 is positioned in the throttle portion 151 beyond the large diameter portion 154 as shown in FIG. In this state, the flow passage area of the first passage 146 is smaller than the flow passage area of the second passage 147.
The configuration other than that described above is the same as that of the first embodiment, and the same members as those of the first embodiment are given the same reference numerals used in the first embodiment plus “100”. Yes.
[0018]
As can be understood from the above configuration, even in the second embodiment, when the brake pedal is depressed relatively gently and during normal operation where the brake pedal is depressed slightly earlier than this, a part of the orifice passage 143 is formed. Since the flow passage area of the first passage 146 is larger than the flow passage area of the second passage 147, which is a substantial orifice passage 143, the brake pedal depressing speed increases as in the first embodiment. The brake booster can be operated with a light pedal effort.
On the other hand, when the valve plunger 119 is suddenly operated at a stroke to the forward end position with respect to the valve body 103, the throttle portion 156 on the valve plunger 119 side enters the throttle portion 155 on the valve body 103 side and enters the first position. The flow passage area of the passage 146 is smaller than the flow passage area of the second passage 147.
As a result, the amount of air introduced into the second variable pressure chamber 140 by the restricting portion 155 and the restricting portion 156 during the sudden braking is greatly reduced as compared with that during normal operation, thereby causing the differential pressure acting on the reaction force piston 138. Is significantly slower than during normal operation, so that the brake booster can be operated suddenly with a small pedal effort.
It should be noted that the throttle portions 155 and 156 of the second embodiment have no effect of eliminating the non-reactive operating section after the full load state of the brake booster as described in the first embodiment.
[0019]
Next, FIG. 6 shows a third embodiment of the present invention. In the first embodiment and the second embodiment described above, the input side members 4 and 104 are composed of a plurality of members, that is, cylindrical members 6 and 106, outer members 7 and 107, and inner members 8 and 108, and The output side members 5 and 105 are also composed of the plurality of rear side members 10 and 110 and the front side members 11 and 111. However, in the third embodiment, the input side member 204 is a single member formed integrally. At the same time, the output side member 205 is also a single member integrally molded.
That is, the valve body 203 is provided integrally with the substantially cylindrical input side member 204, which is slidably fitted in the cylindrical portion 202A of the rear shell 202, and the power piston 214 and the output shaft 235. A bottomed cylindrical output side member 205 slidably fitted to the input side member 204 from the opened rear side is provided.
The output side member 205 has a large diameter portion 205A formed therein with a slightly larger diameter than the front side end portion 204A of the input side member 204, and a smaller diameter on the front side of the large diameter portion 205A. The formed small-diameter portion 205B and the retainer 212 disposed on the rear side with respect to the front-side end portion 204A fitted in the large-diameter portion 205A are provided, whereby the output-side member 205 is connected to the input-side member 204. On the other hand, relative displacement between the small diameter portion 204B and the retainer 212 can be achieved.
By the way, in the present embodiment, unlike the first and second embodiments, the spring 213 is not elastically mounted on the input side member 204 and the output side member 205 but on the input side member 204 and the reaction force piston 238. I am armed.
Thereby, at the time of operation, a part of the retreating force of the reaction force piston 238 is transmitted to the input side member 204 via the spring 213, so that the input side member 204 is in contact with the retainer 212 immediately after the operation starts. The member 205 moves backward relative to the member 205. As described above, when the distance between the input side member 204 and the output side member 205 is maximized immediately after the operation starts, the brake output (braking force) rises suddenly with respect to the depression of the brake. Control becomes difficult.
For this reason, in this embodiment, a spring 228 having a smaller set load than that of the spring 213 is mounted between the input side member 204 and the retainer 212 in order to counter the backward force transmitted from the reaction force piston 238. The spring 228 determines the distance between the input side member 4 and the output side member 5 according to the magnitude of the retreating force of the reaction force piston 238, in other words, according to the operation amount of the brake pedal.
When not shown, the input side member 204 is engaged with the key member 232 that is in contact with the rear shell 202 by the elastic force of the return spring 234, and the output side member 205 is engaged with the front end 204 </ b> A of the input side member 204. In this state, the input side member 204 is advanced relative to the output side member 205.
In the third embodiment, as the configuration of the input side member 204 and the output side member 205 is changed, the configuration of the orifice passage 243 that connects the second variable pressure chamber 240 and the variable pressure chamber B is also the first embodiment. This is different from the configuration of the example and the second embodiment.
That is, in the first and second embodiments, the large diameter portions 19b and 119b of the valve plungers 19 and 119 are inserted into the inner members 4 and 104, but in this embodiment, the large diameter portion 219b of the valve plunger 219 is inserted. Is accommodated in a recess 238B formed at the tip of the protrusion 238A of the reaction force piston 238, so that the orifice passage 243 is only the portion corresponding to the second passages 47 and 147 of the first and second embodiments. It is formed with.
The configurations other than those described above are basically the same as those in the first and second embodiments. The same reference numerals used in the first embodiment are used for the same members as those in the first embodiment. The code with the added is attached.
Even in the third embodiment having the above-described configuration, it is possible to make it operate rapidly with a lighter pedaling force than in the normal operation, as in the first and second embodiments.
[0020]
In the first to third embodiments, the input side members 4, 104, 204 and the output side members 5, 105, 205 constituting the valve body 3, 103, 203 are slidably provided. The present invention is not limited, and the input side members 4, 104, 204 and the output side members 5, 105, 205 may be connected so as not to be relatively displaced. In this case, the stroke shortening means 60 becomes unnecessary because the stroke shortening means 60 cannot shorten the stroke of the input shaft.
In the first embodiment, the stroke shortening means 60 reduces the amount of stepping during a sudden operation as compared with a normal operation, but the stroke shortening means 60 is not necessarily provided and may be omitted as appropriate. .
[0021]
Next, FIG. 7 shows a fourth embodiment of the present invention. In any of the first to third embodiments described above, the present invention is applied to a pneumatic booster. In the embodiment, the present invention is applied to a hydraulic booster integrated with a master cylinder.
In FIG. 7, a bottomed cylindrical power piston 302 is slidably fitted in a small diameter portion of a substantially cylindrical housing 301, and the left end portion of the power piston 302 is connected to the first brake hydraulic pressure of the master cylinder 303. The chamber 304 is kept liquid-tight.
The master cylinder 303 is a cylindrical inner member 306 fitted in the large-diameter portion of the housing 301 in a liquid-tight manner, and the inner member 306 is press-fitted into the large-diameter portion of the housing 301 from the opening side. The inner member 306 is slidably fitted to the inner member 306 and a bottomed outer member 307 that is sandwiched between the steps of the housing 301 and seals the opening of the left end portion of the housing 301. And a piston 308 interlocking with the power piston 302. The first brake hydraulic pressure chamber 304 is formed between the piston 308 and the power piston 302, and between the piston 308 and the outer member 307. A second brake fluid pressure chamber 309 is formed. That is, in this embodiment, the power piston 302 is also used as the piston of the first brake fluid pressure chamber 304 of the master cylinder 303, so that the output shaft is omitted.
In addition, a first spring 311 is elastically mounted between the power piston 302 and the piston 308, and a second spring 312 is elastically mounted between the piston 308 and the outer member 307. During operation, the power piston 302 is brought into contact with a plug 313, which will be described in detail later, and the piston 308 is brought into contact with a retractable contracting rod 314 disposed between the power piston 302 and the power piston 302.
The contracting rod 314 includes a rod portion 315 that contacts the power piston 302 and a bell-shaped sliding portion 316 that is slidably fitted to the rod portion 315 and contacts the piston 308. The first spring 311 is elastically placed in a contracted state between the sliding portion 316 and a retainer 317 provided at the right end of the rod portion 315, and the elastic force of the first spring 311 is shown in a non-actuated state. Thus, the sliding portion 316 is brought into contact with the step portion formed at the left end of the rod portion 315. In this state, the set load of the first spring 311 is set to be slightly larger than the set load of the second spring 312.
The first brake fluid pressure chamber 304 and the second brake fluid pressure chamber 309 include passages 320 and 321 formed in the piston 308 and the power piston 302 and a passage 322 formed in the housing 301 when the hydraulic booster is not in operation. 323 communicates with a reservoir 324 provided integrally with the housing 301 via the H.323, and communicates with a wheel cylinder (not shown) via other passages 325 and 326 formed in the housing 301.
On the other hand, when the hydraulic booster is operated and the power piston 302 and the piston 308 are advanced, the communication between the reservoir 324 and the first brake hydraulic pressure chamber 304 and the second brake hydraulic pressure chamber 309 is cut off. However, the first brake fluid pressure chamber 304, the second brake fluid pressure chamber 309, and each wheel cylinder are in communication.
As a result, when the hydraulic booster is operated and the power piston 302 moves forward, the piston 308 also moves forward accordingly, and is generated in the first brake hydraulic pressure chamber 304 and the second brake hydraulic pressure chamber 309. Each hydraulic pressure is supplied to the wheel cylinder to perform a braking action.
[0022]
Next, the configuration of the hydraulic booster will be described with reference to FIGS.
The right end opening of the housing 301 is sealed by the plug 313, and a power chamber 330 into which pressure oil is introduced is formed between the plug 313 and the power piston 302.
The power piston 302 of the present embodiment has a bottomed cylindrical output side member 331 facing the first brake hydraulic pressure chamber 304 of the master cylinder 303, and is slidable while maintaining fluid tightness in the output side member 331. An input side member 332 provided between the output side member 331 and the input side member 332, and a spring 333 as a biasing means is mounted between the output side member 331 and the input side member 332 by the spring 333. The member 331 is urged to the right, and the input member 332 is brought into contact with the partition wall of the output member 331 in the non-actuated state.
A stepped sleeve 334 is integrally provided in the input side member 332 while maintaining liquid tightness, and a distal end of the left end portion of the sleeve 334 serves as a first valve seat 336 constituting the valve mechanism 335. Further, a valve body 337 constituting a valve mechanism 335 is provided in the input side member 332, and the valve body 337 has a shaft portion 339 that is slidably passed through the collar 338 while maintaining liquid tightness. And a ball 340 provided at the right end of the shaft portion 339. The valve body 337 is a first valve in the non-actuated state shown in the figure by an elastic force of a spring 341 elastically mounted between the valve 338 and the collar 338. The seat 336 is adapted to be seated.
The pressure chamber 344 formed between the valve body 337 and the first valve seat 336 includes a passage 345 formed in the input side member 332, a passage 346 formed in the output side member 331, and a passage formed in the housing 301. 347 and a conduit 349 (see FIG. 7) connected thereto, and communicated with a pump (not shown) to supply pressure oil of a predetermined pressure to the pressure chamber 344 at all times. I can do it. Although not shown, an accumulator for accumulating pressure oil generated by the pump is provided downstream of the pump.
Further, the balance chamber 351 formed between the valve body 337 and the input side member 332 communicates with the power chamber 330 through a communication passage 352 formed in the input side member 332 and a through hole 353 provided in the sleeve 334. The pressure oil can be introduced into the balance chamber 351 when the pressure oil is introduced into the power chamber 330. The balance chamber 351 is provided to urge the valve body 337 with an urging force similar to the urging force received from the pressure oil in the pressure chamber 344 when the valve body 337 is opened. Thus, when the pedaling force is released from the operating state, the valve body 337 can be seated on the first valve seat 336 by the elastic force of the spring 341.
Further, the urging chamber 355 formed between the power piston 302 and the input side member 332 also has a communication passage 352 formed in the input side member 332 and a through hole 353 provided in the sleeve 334, similarly to the balance chamber 351. The pressure chamber is communicated with the power chamber 330 through which pressure oil can be introduced into the biasing chamber 355 when the pressure oil is introduced into the power chamber 330. The urging chamber 355 is for retracting the input side member 332 relative to the output side member 331 when the hydraulic pressure booster is operated, and thus faces the urging chamber 355. The area of the input side member 332 is set larger than the area facing the power chamber 330.
An input shaft 356 interlocked with a brake pedal (not shown) is slidably fitted in the plug 313 so as to be slidable, and the valve mechanism 335 is configured at the tip of the input shaft 356. A second valve seat 357 is formed. A spring 358 is mounted between the input shaft 356 and the sleeve 334. The spring 358 urges the input shaft 356 to the right to release the brake pedal. Then, the second valve seat 357 is separated from the valve body 337.
A passage 360 communicating with the power chamber 330 is formed in the shaft portion of the input shaft 356. The power chamber 330 includes a passage 361 formed in the passage 360 and the plug 313, and a passage 362 formed in the housing 301. It is possible to communicate with the reservoir 324 via a discharge passage 364 formed from the pipe and a conduit 365 (see FIG. 7) connected thereto.
As a result, the valve body 337 is seated on the first valve seat 336 of the sleeve 334, and the hydraulic fluid introduced into the pressure chamber 344 is inactive when the hydraulic booster that is separated from the second valve seat 357 of the input shaft 356 is not operating. Is recovered in the reservoir 324 via the power chamber 330 and the discharge passage 364, so that the pressure oil does not act on the output side member 331 and the input side member 332.
On the other hand, when the brake pedal is depressed and the input shaft 356 is moved forward, the second valve seat 357 formed at the tip of the input shaft 356 is brought into contact with the valve body 337 so that the power chamber 330 and the discharge passage are brought into contact. 364 is blocked, and the valve body 337 is separated from the first valve seat 336 by the input shaft 356, so that the pressure oil introduced into the pressure chamber 344 is introduced into the power chamber 330, and the power The output side member 331 and the input side member 332 of the power piston 302 are advanced by the pressure oil introduced into the chamber 330. At this time, the pressure oil in the power chamber 330 acts on the tip of the input shaft 356 that passes through the plug 313 and faces the power chamber 330, and the pressure oil acting on the input shaft 356 acts as a reaction force on the driver. Will be communicated.
When the depression of the brake pedal is released from the above-described operating state, the brake pedal and the input shaft 356 are retracted, and the valve body 337 is seated on the first valve seat 336 of the sleeve 334 and the pressure chamber 344 is powered. The communication with the chamber 330 is cut off, and the second valve seat 357 of the input shaft 356 is separated from the valve body 337, so that the pressure oil introduced into the power chamber 330 passes through the discharge passage 364 and the conduit 365. Then, it is discharged to the reservoir 324 and returns to the non-operating position shown in the figure.
[0023]
In this embodiment, a fluid pressure reaction force mechanism 370 that applies a reaction force to the input shaft 356 is provided separately from the reaction force of the power chamber 330 due to the pressure oil.
That is, as shown in FIG. 8, the fluid pressure reaction force mechanism 370 is formed on the step 371 formed between the rear-side large diameter portion and the front-side small diameter portion of the input shaft 356 and the inner peripheral surface of the plug 313. A reaction force chamber 372 formed so as to surround the stepped portion 371, and the reaction force chamber 372 communicates with a passage 360 of the input shaft 356 and also communicates with a passage 361 formed in the plug 313. Yes.
Further, as shown in FIG. 7, the fluid pressure reaction force mechanism 370 is formed in the housing 301 and communicates with the reaction chamber 373 communicating with the power chamber 330, and a conduit 374 communicating the reaction force passage 373 and the conduit 365. And a flow path switching valve 375 provided between the conduit 365 and the conduit 374 for switching the flow path between the two conduits.
The flow path switching valve 375 causes the power chamber 330 and the reservoir 324 to communicate with each other until the pressure oil in the power chamber 330 supplied via the reaction force passage 373 and the conduit 374 exceeds a preset pressure. The communication between the power chamber 330 and the reaction force chamber 372 is cut off, but when the pressure oil from the power chamber 330 exceeds the set pressure, the flow path is automatically switched by the force of the pressure oil, The communication between the power chamber 330 and the reservoir 324 is cut off, and the power chamber 330 and the reaction force chamber 372 are communicated with each other.
As understood from this, the pressure oil supplied to the power chamber 330 is introduced into the reaction force chamber 372 via the reaction force passage 373, the passage switching valve 375 and the discharge passage 364. The pressure oil in the reaction force chamber 372 acts on the step portion 371 of the input shaft 356 to urge the input shaft 356 to the right.
As a result, the sum of the reaction force of the power chamber 330 acting on the input shaft 356 and the reaction force of the reaction force chamber 372 is transmitted to the driver as a brake reaction force.
[0024]
Furthermore, in this embodiment, reaction force reducing means 380 for reducing the reaction force transmitted from the fluid pressure reaction force mechanism 370 is provided.
The reaction force reducing means 380 includes an orifice 381 provided in a conduit 365 between the flow path switching valve 375 and the discharge passage 364, a conduit 382 disposed so as to bypass the front and rear of the orifice 381, and the conduit The pressure oil in the power chamber 330 is prevented from being introduced into the reaction force chamber 372 via the conduit 382, while the pressure oil in the reaction force chamber 372 or the power chamber 330 is stored in the reservoir via the conduit 382. A check valve 383 that allows the gas to be discharged to 324, and provided between the flow path switching valve 375 and the orifice 381, temporarily when the fluid pressure in the conduit 365 rises above a predetermined pressure. And a damper 384 for storing the pressure oil in 365 and preventing the orifice 381 or the flow path switching valve 375 from being damaged.
As understood from this, the amount of pressure oil introduced into the reaction force chamber 372 by the orifice 381 is always a constant amount without being affected by fluctuations in the amount of pressure oil introduced into the power chamber 330. .
[0025]
The operation of the hydraulic booster having the above-described configuration will be described.
First, when the brake pedal is depressed relatively slowly from the non-operating state described above, the second valve seat 357 formed at the tip of the input shaft 356 abuts against the valve body 337 as shown in FIG. The communication between the chamber 330 and the discharge passage 364 is blocked, and the valve body 337 is separated from the first valve seat 336 formed in the sleeve 334 so that the pressure chamber 344 and the power chamber 330 communicate with each other. As a result, pressure oil is introduced from the pressure chamber 344 to the power chamber 330, so that the output side member 331 and the input side member 332 of the power piston 302 are advanced by this pressure oil.
At this time, the advance amount of the input side member 332 is relatively smaller than the advance amount of the output side member 331.
That is, since the biasing force to the right acts on the input side member 332 by the pressure oil introduced into the biasing chamber 355, the input side member is maintained while the biasing force is smaller than the set load of the spring 333. 332 advances integrally with the output side member 331. However, when the urging force exceeds the set load of the spring 333, the input side member 332 resists the elastic force of the spring 333 during the advancement, and the output side member 331 is moved forward. That is, the advance amount of the input side member 332 is smaller than the advance amount of the output side member 331.
As understood from this, in this embodiment, since the advance amount of the input side member 332 that accommodates the valve mechanism 335 is set smaller than the advance amount of the output side member 331, the input side member 332 moves forward. Since the stroke of the input shaft 356 and the brake pedal linked with the input shaft 356 can be relatively reduced, the brake feeling is compared with the case where the valve mechanism 335 is provided directly on the power piston 302 as in the prior art. Can be improved.
Further, since the pressure oil is introduced into the reaction force chamber 372 through the orifice 381, the pressure oil in the reaction force chamber 372 and the pressure oil in the power chamber 330 described above act on the input shaft 356, and the pressure of both Since the oil is transmitted to the brake pedal interlocked with the input shaft 356, the driver can know the operational feeling of the brake.
The timing at which the input side member 332 is separated from the output side member 331 and the speed at the time of separation can be adjusted by the set load and the spring constant of the spring 333.
[0026]
Next, the operation when the brake pedal is suddenly depressed will be described. In such a sudden operation, the valve body 337 is moved to the input side member 332 by the second valve seat 357 of the input shaft 356 than in the normal depression. On the other hand, it will be greatly advanced.
As a result, the valve body 337 is separated from the first valve seat 336 formed on the sleeve 334 by a larger distance than that during normal depression, so that a large amount of power is supplied to the power chamber 330 via the first valve seat 336 and the valve body 337. This pressure oil is introduced, whereby the output side member 331 is rapidly advanced to perform rapid braking.
On the other hand, since only the same amount of pressure oil as that during normal operation is supplied to the reaction force chamber 372 through the orifice 381, the pressure increase of the pressure oil in the reaction force chamber 372 is relative to the increase in output. Ascend late.
As a result, the reaction force applied to the brake pedal by the fluid pressure reaction force mechanism 370 is reduced during a sudden operation, so that the hydraulic booster can be suddenly operated with a small force.
[0027]
Next, FIGS. 10 and 11 show a fifth embodiment of the present invention. In the fourth embodiment, the fluid pressure reaction force mechanism 370 and the reaction force reducing means 380 are provided. These are omitted, and the stroke shortening means 490 for shortening the depression amount more than the normal depression when the hydraulic booster is suddenly operated is provided alone. The stroke shortening means 490 can be provided in combination with the fluid pressure reaction force mechanism 370 and the reaction force reducing means 380. In this case, the stroke shortening means 490 may be slightly changed in design. .
Thus, the stroke shortening means 490 includes a passage 491 (see FIG. 11) formed in the output side member 431 and communicating with the biasing chamber 455 and a passage 492 formed in the housing 301 and communicating with the passage 491 (FIG. 11). ), A conduit 494 connecting the bias passage 493 and the pump, an on-off valve 495 provided in the conduit 494, and opening and closing during non-operation and normal operation A control device that closes the valve 495 to prevent the pressure oil from being introduced into the biasing chamber 455 and supplies the pressure oil to the biasing chamber 455 by opening the on-off valve 495 when it is determined to be suddenly operated. 496. A detection value is input to the control device 496 from a sensor (not shown) that detects a pedaling force or a stroke speed acting on the brake pedal, and the control device 496 includes a detection value and a preset reference value. When the detected value exceeds the reference value, it is determined that the braking is suddenly performed and the on-off valve 495 is opened.
Also, in this embodiment, unlike the fourth embodiment, the space between the urging chamber 455 and the communication passage 452 is closed so that the pressure oil does not escape from the urging chamber 455 through the communication passage 452. Yes.
The configuration other than that described above is the same as that of the fourth embodiment, and the same members as those of the fourth embodiment are denoted by reference numerals obtained by adding “100” to the reference numerals used in the fourth embodiment. .
[0028]
The operation of the hydraulic booster having the above-described configuration will be described.
First, when the brake pedal is depressed relatively slowly from the non-operating state described above, the second valve seat 457 formed at the tip of the input shaft 456 contacts the valve body 437 and the discharge passage 464 and the power chamber 430 are connected. The communication is cut off, and the valve body 437 is separated from the first valve seat 436 formed on the sleeve 434 so that the pressure chamber 444 and the power chamber 430 communicate with each other. As a result, pressure oil is introduced from the pressure chamber 344 to the power chamber 430, so that the output side member 431 and the input side member 432 of the power piston 402 are advanced by this pressure oil.
Thus, when the brake pedal is depressed relatively gently, the driver can operate with the same operation feeling as that of a conventional general hydraulic pressure doubler.
[0029]
Next, the operation when the brake pedal is suddenly operated will be described. During such a rapid operation, specifically, when the control device 496 determines a sudden braking, the second valve seat 457 of the input shaft 456 causes the valve body 437 to be larger than the input side member 432. Be moved forward.
As a result, the valve body 437 is greatly separated from the first valve seat 436 formed on the sleeve 434, so that a large amount of pressurized oil is introduced into the power chamber 430 via the space between the first valve seat 436 and the output. The side member 431 is rapidly advanced and sudden braking is performed.
In synchronism with this, the control device 496 of the stroke shortening means 490 determines that sudden braking is performed, so that the on-off valve 495 that has been closed is opened and the pressure oil is forcibly supplied to the biasing chamber 455. The
As a result, the pressure oil from the pump is introduced into the biasing chamber 455 in addition to the pressure oil introduced from the power chamber 430, so that the input side member 432 is in normal operation with respect to the output side member 431. It will come apart on the near side.
As a result, the amount of depression that the driver steps on is shortened by an amount that the input side member 432 is separated from the output side member 431 on the near side of the normal operation. This can be shortened compared with the time of operation, thereby improving the response of the hydraulic booster and shortening the braking distance.
[0030]
In the fourth embodiment, the output side member 331 and the input side member 332 that accommodates the valve mechanism 335 are provided so as to be relatively displaceable. However, the present invention is not limited to this, and the output side member 331 includes the input side member 332. May be fixed so that relative displacement is impossible.
In the fourth embodiment, the control device 496 is set so as to reduce the amount of depression of the brake pedal only during sudden braking. However, the control device 496 is not limited to this. You may perform the setting which sends the pressure oil according to the operation amount of a pedal.
[0031]
【The invention's effect】
As described above, in the present invention, the reaction force required by the fluid pressure reaction force mechanism can be transmitted to the driver during normal depression, and the reaction force transmitted to the driver by the reaction force reduction means during sudden operation. Therefore, it is possible to obtain an effect that the booster can be suddenly operated with a lighter pedaling force than usual.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a first embodiment of the present invention.
FIG. 2 is an enlarged cross-sectional view of a main part showing a state during sudden braking in FIG. 1;
FIG. 3 is an enlarged cross-sectional view showing a full load state of FIG. 1;
FIG. 4 is a sectional view showing a second embodiment of the present invention.
FIG. 5 is an enlarged cross-sectional view of a main part showing a state of sudden braking in FIG. 4;
FIG. 6 is a sectional view showing a third embodiment of the present invention.
FIG. 7 is a sectional view showing a fourth embodiment of the present invention.
8 is an enlarged cross-sectional view of the main part of FIG.
9 is an enlarged cross-sectional view of a main part showing the operating state of FIG. 7;
FIG. 10 is a sectional view showing a fifth embodiment of the present invention.
11 is an enlarged cross-sectional view of a main part showing the operating state of FIG.
[Explanation of symbols]
3, 103, 203 ... Valve body
4, 104, 204, 331, 431 ... input side member
5, 105, 205, 332, 432 ... output side member
6, 106 ... cylindrical member
7, 107 ... outer member
8, 108 ... inner member
10, 110 ... Rear side member
11, 111 ... front side member
17, 117, 217, 335, 435 ... valve mechanism
19, 119, 219 ... valve plunger
30, 130, 230, 356, 456 ... input shaft
37, 137, 237, 370 ... Fluid pressure reaction force mechanism
38, 138, 238 ... Reaction force piston
39, 139, 239 ... second constant pressure chamber
40, 140, 240 ... second transformation chamber
42, 380 ... Reaction force reducing means
43, 143, 243 ... Orifice passage
51. Sealing member
155, 156 ... Aperture section
60, 490 ... Stroke shortening means
381 ... Orifice
A ... Constant pressure chamber
B ... Transformer room

Claims (11)

A pneumatic booster having an input shaft linked to the brake pedal, a master cylinder linked to the output shaft of the booster, and a wheel cylinder operated by the output hydraulic pressure of the master cylinder;
The pneumatic booster is provided in a valve body slidably provided in a shell, a power piston provided in the valve body, a constant pressure chamber and a variable pressure chamber formed before and after the power piston, and the valve body. A valve mechanism that controls the switching of the flow path, a valve plunger that is slidably provided in the valve body and forms a part of the valve mechanism, and the valve plunger is moved forward and backward to switch the flow path of the valve mechanism. A brake system including an input shaft to be moved and an output shaft advanced by advance of the power piston,
While configured as the booster is not transmitted to the reaction force of the valve plunger exerted on the output shaft upon actuation, provide a fluid reaction force mechanism that applies a pseudo reaction force on the valve plunger, the fluid reaction force The mechanism is provided slidably on the valve body and has a reaction force piston on which the pressure of the constant pressure chamber and the variable pressure chamber acts, and a differential pressure between the pressure of the constant pressure chamber acting on the reaction force piston and the pressure of the variable pressure chamber The urging force by is transmitted to the valve plunger as a pseudo reaction force,
A brake system comprising a reaction force reducing means for reducing a reaction force transmitted from the fluid pressure reaction force mechanism to the valve plunger when the booster is suddenly operated. The brake system according to claim 1, wherein the reaction force reducing means is an orifice that restricts a flow of fluid in the variable pressure chamber acting on the reaction force piston. The brake system according to claim 2, wherein the orifice is closed when the valve plunger moves forward by a predetermined amount or more with respect to the valve body. The valve body is provided integrally with the power piston and the output shaft and receives a differential pressure between the constant pressure chamber and the variable pressure chamber, and is slidably provided on the output side member and accommodates the valve mechanism. And an input side member that receives a differential pressure between the variable pressure chamber and the atmospheric pressure, and an elastic member elastically provided between the output side member and the input side member, the stroke of the input shaft with respect to the stroke of the output shaft. The brake system according to any one of claims 1 to 3, wherein the brake system is configured to be shortened. The booster includes stroke shortening means for shortening the stroke of the input shaft with respect to the stroke of the output shaft during sudden braking. The stroke shortening means includes an on-off valve that communicates and shuts off the variable pressure chamber and the atmosphere. A control device that controls the opening and closing of the valve, and a sensor that detects a sudden operation of the booster, and the control device opens the on-off valve and introduces the atmosphere into the variable pressure chamber when it is determined that the operation is sudden. The brake system according to claim 4 . The brake system according to claim 1, wherein the reaction force piston is slidably fitted to the valve body, and a seal member is disposed on an outer peripheral portion of the reaction force piston. A hydraulic booster having an input shaft linked to the brake pedal, a master cylinder linked to the output shaft of the booster, and a wheel cylinder operated by the output hydraulic pressure of the master cylinder;
The hydraulic booster is provided with a power piston slidably provided in a housing, a power chamber formed at one end of the power piston in the housing, and provided in the power piston and operating in conjunction with an input shaft. A valve mechanism that switches the flow path, a supply passage that communicates the power chamber and the pressure fluid source via the valve mechanism, a discharge passage that communicates the power chamber with the reservoir via the valve mechanism, and An output shaft that is advanced by the advance of the power piston, and when the brake pedal is depressed and the hydraulic booster is operated, the hydraulic pressure in the power chamber is transmitted to the input shaft as a reaction force. in the brake system,
In addition to the hydraulic pressure in the power chamber, a fluid pressure reaction force mechanism capable of transmitting reaction force to the input shaft is provided, and is transmitted from the fluid pressure reaction force mechanism to the input shaft when the hydraulic booster is suddenly operated. The reaction force reducing means to reduce the reaction force is provided ,
During normal braking operation in which the brake pedal is gently depressed, the hydraulic pressure of the power chamber and the reaction force of the fluid pressure reaction force mechanism are transmitted to the input shaft as a brake reaction force,
A brake system, wherein the reaction force transmitted from the fluid pressure reaction force mechanism to the input shaft is reduced by the reaction force reduction mechanism when the brake pedal is suddenly depressed . The fluid pressure reaction force mechanism includes a step portion that is formed on the input shaft and transmits the reaction force to the input shaft when hydraulic pressure is applied, and a reaction force chamber that surrounds the step portion, and the discharge passage is The power chamber communicates with the reservoir through the reaction force chamber,
Furthermore, the fluid pressure reaction force mechanism includes a reaction force passage that allows the power chamber to communicate with the reaction force chamber, and shuts off the communication between the reaction force chamber and the power chamber when the pressure of the power chamber is equal to or lower than a predetermined value. A flow path switching valve is provided that communicates the reaction force chamber with the reservoir, while shutting off the communication between the reaction force chamber and the reservoir when the pressure is equal to or higher than a predetermined value, and communicating the reaction force chamber with the power chamber. The brake system according to claim 7 . The brake system according to claim 8, wherein the reaction force reducing means is an orifice that is provided in the reaction force passage and restricts a flow of fluid from the power chamber to the reaction force chamber. The power piston is provided integrally with the output shaft and receives the hydraulic pressure in the power chamber; the power piston is slidably provided on the output side member and houses the valve mechanism; An input side member in which the pressure receiving area of the front side end surface receiving the hydraulic pressure is set larger than the pressure receiving area of the rear side end surface; and an urging means for urging the input side member to the front side, The brake system according to any one of claims 7 to 9 , characterized in that the stroke of the input shaft relative to the stroke of the shaft can be shortened. The booster includes stroke shortening means for shortening the stroke of the input shaft with respect to the stroke of the output shaft during sudden braking, and the stroke shortening means is provided on the output side member so that the front side end face of the input side member is An energizing chamber that surrounds, an on-off valve that communicates and shuts off the energizing chamber and the pump, a control device that controls opening and closing of the on-off valve, and a sensor that detects a sudden operation of the booster, 11. The brake system according to claim 10, wherein the device opens the on-off valve and introduces pressure oil into the biasing chamber when it is determined that the device is suddenly operated.

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