JP3695556B2 - Booster reaction force mechanism - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a booster used for a brake or the like of an automobile, and more particularly to a reaction force mechanism of a booster that applies a reaction force to an operating rod that operates the booster.
[0002]
[Prior art]
In general, a brake booster generally includes 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 a valve body. The valve mechanism for switching the communication state of the flow path in the valve body, the valve plunger constituting a part of the valve mechanism, and the valve plunger are moved forward and backward in conjunction with the operating rod. An input shaft to be actuated and an output shaft advanced by the advancement of the valve body are provided.
The reaction force mechanism of a conventional general brake booster includes a rubber reaction disk disposed between the output shaft and the valve plunger. When the brake booster is operated, the reaction disk is connected to the valve body and the valve body. The valve plunger is contacted at the same time, and a part of the brake reaction force applied to the output shaft is received by the valve body, and the remainder is transmitted to the valve plunger, and the brake reaction force applied to the valve plunger is transmitted via the input shaft and the brake pedal. To make the driver sense.
At this time, the servo ratio of the brake booster can be changed by changing the ratio of 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. it can.
[0003]
[Problems to be solved by the invention]
By the way, the servo ratio of the brake booster is generally set to be large so that a large brake fluid pressure can be generated with a small depression force of the brake pedal. However, it has been found that it is difficult to perform rapid braking by a weak driver such as an elderly person or a woman.
That is, when the brake pedal is depressed, the valve mechanism is actuated via the input shaft and the flow path in the valve body is switched, whereby pressure fluid is introduced into the variable pressure chamber and the power piston and the valve body move forward. Will come to be. 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 applied to the output shaft as described above. Force is distributed to the valve body and the valve plunger.
However, during sudden braking, the valve plunger that is linked to the brake pedal via the input shaft is advanced before the power piston and valve body are advanced by the pressure fluid introduced into the variable pressure chamber. Most of the applied 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 gradually depress the brake pedal to obtain a large braking force. Compared to the case, the brake force required for sudden braking could not be obtained unless the brake pedal was depressed with much greater force.
In view of such circumstances, the present invention provides a reaction force mechanism of a booster device that can obtain a large output with a light pedal force even during a sudden operation without impairing the operation feeling of a normal booster device. It is.
[0004]
[Means for Solving the Problems]
That is, the present invention includes 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 a valve body. A valve mechanism for switching the communication state of the flow path in the valve body, a valve plunger constituting a part of the valve mechanism, and an input shaft for operating the valve mechanism by moving the valve plunger forward and backward in conjunction with an operating rod. And a booster comprising an output shaft that is advanced by advancement of the valve body,
The output shaft is engaged with the valve body so that the reaction force of the output acting on the output shaft is not transmitted to the valve plunger when the booster is operated, and according to the amount of movement of the input shaft. A pseudo reaction force applying means for applying the pseudo reaction force to the operating rod. The pseudo reaction force applying means is provided on the rear side by an elastic member disposed in the constant pressure chamber and an elastic force of the elastic member. A reaction force piston that is biased and can come into contact with the valve plunger,
In addition, a separation means for separating the reaction force piston and the valve plunger facing the reaction force piston in a non-operating state of the booster is provided, and the separation means includes a key member engaged with the valve plunger. In a non-operating state, a reaction force mechanism of a booster is provided in which the reaction force piston and the valve plunger are separated from each other by the key member coming into contact with the shell .
[0005]
[Action]
According to the above configuration, the reaction force applied to the output shaft during operation of the booster is not transmitted to the valve plunger. Therefore, during sudden operation, the power piston and the valve body are moved by the pressure fluid introduced into the variable pressure chamber. Even if the valve plunger that is linked to the operating rod via the input shaft is advanced before being advanced, the reaction force applied to the output shaft is transmitted to the driver via the valve plunger, the input shaft, and the operating rod. Never happen.
On the other hand, since the pseudo reaction force applying means transmits a pseudo reaction force according to the amount of movement of the operating rod to the driver via the operating rod, the reaction force becomes abnormally large at the time of sudden operation as in the prior art. In the case of sudden operation, a large output can be obtained with a light operating force as in the case of normal operation.
In addition, when the booster is not in operation, the reaction force piston and the valve plunger facing the piston are separated by the separating means, so that after the brake pedal is depressed and the booster is activated, The reaction force piston and the valve plunger come into contact with each other after (input) has risen slightly, and the pseudo reaction force is transmitted to the driver from that point. That is, although the reaction disk is omitted, the same jumping characteristic as that of a general reaction force mechanism can be obtained.
[0006]
【Example】
Hereinafter, an embodiment in which the present invention is applied to a brake booster will be described. In FIG. 1, a substantially cylindrical valve body 3 is slidably provided in a sealed container composed of a front shell 1 and a rear shell 2. A sealed container is partitioned into a constant pressure chamber 6 on the front side and a variable pressure chamber 7 on the rear side by a power piston 4 provided on the outer periphery of the valve body 3 and a diaphragm 5 attached to the rear side thereof. .
A valve mechanism 8 for switching a fluid circuit is accommodated in the valve body 3. The valve mechanism 8 includes an annular first valve seat 11 formed on the inner peripheral portion of the valve body 3, and an inside of the valve body 3. An annular second valve seat 13 formed at the rear end of the valve plunger 12 slidably fitted to the valve plunger 12, and a valve body seated on both valve seats 11 and 13 by a spring 14 from the right in FIG. 15.
[0007]
The outer periphery of the first valve seat 11 communicates with the constant pressure chamber 6 through an axial constant pressure passage 16 formed in the valve body 3, and the constant pressure chamber 6 is connected to the front shell 1. A negative pressure is always introduced into the constant pressure chamber 6 by communicating with the intake manifold of the engine via the introduction pipe. An intermediate portion between the first valve seat 11 and the second valve seat 13 communicates with the variable pressure chamber 7 via a radial variable pressure passage 17 formed in the valve body 3, and further than the second valve seat 13. The inner peripheral side communicates with the atmosphere via a pressure passage 18 formed in the valve body 3.
The end of the input shaft 21 is pivotally connected to the rear end of the valve plunger 12, and the end of the input shaft 21 is interlocked with a brake pedal (operating rod) (not shown). Further, the valve plunger 12 is prevented from being pulled out from the valve body 3 by the key member 22. Although not shown, the key member 22 is formed in a bifurcated shape from the center to the tip, and the key member 22 is inserted into the insertion hole 23 of the radial hole formed in the valve body 3 to The base portion of the bifurcated portion is engaged with the small diameter portion 12 a of the valve plunger 12.
[0008]
At this time, the key member 22 can be displaced in the axial direction of the valve body 3 in the insertion hole 23, and the key member 22 and the valve plunger 12 are within the range of the axial length of the small diameter portion 12a. The valve body 3 can be displaced in the axial direction. When the brake booster is not operated, a part of the key member 22 located outside the valve body 3 is brought into contact with the wall surface of the rear shell 2 so that the key member 22 and the valve plunger 12 are moved forward with respect to the valve body 3. By holding, the loss stroke of the input shaft 21 at the start of operation of the brake booster can be reduced.
Further, an annular protrusion 3 a is projected from the inner peripheral portion of the valve body 3 toward the front side, and a recess 24 a provided at the base of the output shaft 24 is fitted into the annular protrusion 3 a. The front end of the output shaft 24 is interlocked with a piston of a master cylinder (not shown) connected to the front shell 1.
The valve body 3 and the power piston 4 are urged to the rear side by a return spring 25 and are held at a non-operating position (not shown) in which the key member 22 contacts the wall surface of the rear shell 2.
[0009]
Thus, in this embodiment, in the conventional general booster, the rubber reaction disk disposed between the front end surface 12b of the valve plunger 12 and the recess 24a of the output shaft 24 is omitted. On the other hand, the pseudo reaction force applying means 26 is provided to transmit the pseudo reaction force to the driver.
The pseudo reaction force applying means 26 includes a reaction force piston 27 provided on the front side of the valve body 3 and a spring 31 that is disposed in the constant pressure chamber 6 and urges the reaction force piston 27 toward the rear side. Yes.
The reaction force piston 27 includes a small-diameter portion 27a formed on the rear side, two arm portions 27b extending radially outward from the front-side portion of the small-diameter portion 27a, and further, And a cylindrical portion 27c provided continuously between the two tip portions in the circumferential direction. The small-diameter portion 27a is slidably fitted to the inner peripheral portion of the annular projection 3a of the valve body 3 from the front side so as to be slidable, and the rear end surface of the small-diameter portion 27a is fitted to the valve plunger 12. It faces the end face 12b on the front side.
The recess 24a of the output shaft 24 is fitted to the annular protrusion 3a of the valve body 3, and the rear end of the output shaft 24 is brought into contact with the adjacent stepped end surface of the annular protrusion 3a. These two members are integrally connected so as not to move relative to each other in the axial direction. The base of the output shaft 24 provided with the recess 24a is formed with a slit 24b extending in the axial direction continuously from the rear end, and the both arm portions 27b of the reaction force piston 27 penetrate through the slit 24b. I am letting. Thereby, the reaction force piston 27 can be displaced in the axial direction with respect to the output shaft 24.
A disc-shaped retainer 32 is brought into contact with the front end surface of the cylindrical portion 27 c of the reaction force piston 27 from the front side, and the cylindrical shape of the front shell 1 and the reaction force piston 27 is interposed via the retainer 32. A spring 31 is mounted over the portion 27c.
[0010]
Further, in the present embodiment, the opening on the front side faces the arm portion 27b on the lower side of the reaction force piston 27 at the position on the outer side of the annular protrusion 3a in the valve body 3, and the opening on the rear side is the key member 22. A guide hole 3b in the axial direction is formed opposite to. A pin 33 set to a predetermined length is slidably passed through the guide hole 3b while maintaining airtightness. Since the reaction force piston 27 is biased to the rear side by the spring 31, in the non-actuated state where the key member 22 abuts against the wall surface of the rear shell 2, the rear end of the pin 33 abuts against the key member 22. The front end of the pin 33 is in contact with the arm portion 27b of the reaction force piston 27.
Therefore, in the non-actuated state shown in the figure, the arm portion 27 b of the reaction force piston 27 and the key member 22 are kept separated by the length of the pin 33. As a result, a predetermined gap is maintained between the rear end face of the small diameter portion 27a of the reaction force piston 27 and the end face 12b of the valve plunger 12 facing it. Note that there is also a gap between the arm portion 27b of the reaction force piston 27 and the end surface of the annular protrusion 3a opposite to the arm portion 27b, and between the rear end surface of the cylindrical portion 27c and the stepped end surface of the valve body 3 facing it. However, these gaps are set larger than the gap between the end surface of the small diameter portion 27a and the end surface 12b of the valve plunger 12 described above. In this embodiment, the key member 22 and the pin 33 constitute a separating means 34 that separates the rear end face of the reaction force piston 27 and the end face of the valve plunger 12 facing it.
[0011]
(Description of operation)
In the above configuration, when the brake pedal is depressed and the input shaft 21 and the valve plunger 12 are advanced from the non-actuated state shown in the drawing, the valve mechanism 8 is actuated in the same manner as in a conventionally known brake booster. The flow path in the body 3 is switched and the atmosphere is introduced into the variable pressure chamber 7.
As a result, a pressure difference is generated between the constant pressure chamber 6 and the variable pressure chamber 7, and the power piston 4 and the valve body 3 are moved forward, whereby the output shaft 24 is moved forward, so that brake fluid pressure is generated in the master cylinder. . The brake reaction force due to the brake fluid pressure is all received by the valve body 3 via the output shaft 24 and is not transmitted to the valve plunger 12.
Further, when the valve body 3 is advanced as described above, the key member 22 is separated from the wall surface of the rear shell 2 and is pushed to the rear side by the pin 33, so that the key member 22 is inserted into the insertion hole 23. It moves to the rear side relative to the valve body 3 inside. As a result, the reaction force piston 27 moves relative to the valve body 3 in the rear direction, so that the end surface on the rear side of the small diameter portion 27a of the reaction force piston 27 contacts the end surface 12b of the valve plunger 12. After this time, a pseudo reaction force corresponding to the elastic force of the spring 31 is transmitted to the driver via the reaction force piston 27, the valve plunger 12, and the input shaft 21.
FIG. 3 shows the relationship between the depression force (input) of the brake pedal and the pseudo reaction force transmitted to the driver. The position indicated by P in FIG. 3 is the small diameter portion 27a of the reaction force piston 27. This is a point of time when the rear end surface of the valve contacts the end surface 12b of the valve plunger 12. After this point, the spring 31 is compressed as the input increases, so that a pseudo reaction force proportional to the amount of contraction is transmitted to the driver.
On the other hand, as already described above, the brake reaction force applied to the output shaft 24 is all received by the valve body 3 and therefore is not transmitted to the valve plunger 12 and thus to the brake pedal.
[0012]
Thus, in this embodiment, by providing the separation means 34, the small diameter portion 27a of the reaction force piston 27 and the valve plunger 12 are separated from each other at the start of depression of the brake pedal, and the brake booster is The pseudo reaction force is transmitted to the driver from the time when the small diameter portion 27a of the reaction force piston 27 and the valve plunger 12 come into contact with each other.
Therefore, in the case of the conventional booster at the time when the small diameter portion 27a of the reaction piston 27 and the valve plunger 12 come into contact with each other even though the reaction disk provided in the conventional booster is omitted. The same jumping characteristic can be obtained. As a result, the brake feeling of the driver can be improved compared to the case where the pseudo reaction force is immediately applied to the driver from the start of the depression of the brake pedal.
Further, the pseudo reaction force applied to the brake pedal by the pseudo reaction force applying means 26 is substantially the same during sudden braking and during normal braking, and is abnormally large during sudden braking like the brake reaction force of the conventional device. There will never be. Therefore, according to the present embodiment, a large braking force can be obtained with a relatively light pedaling force even during a sudden braking, and thus a sudden braking operation can be reliably performed even by a non-powerful driver such as an elderly person or a woman. .
Further, when the brake booster described above is released from the operating state, that is, when the depression of the brake pedal is released, the reaction force piston 27 comes into contact with the end surface of the annular protrusion 3a of the valve body 3 and moves backward. However, since the valve plunger 12 is retracted with respect to the valve body 3 until the retraction thereof is restricted by the key member 22, the valve plunger 12 is separated from the small diameter portion 27 a of the reaction force piston 27. .
When the pressure in the variable pressure chamber 7 decreases due to the switching of the flow path by the valve mechanism 8, the power piston 4 and the valve body 3 are retracted to the rear side by the return spring 25, and first the key member 22 contacts the wall surface of the rear shell 2. Then, the backward movement is restricted, but the backward movement of the valve body 3 continues, and then the valve body 3 comes into contact with the key member 22 and stops. Immediately after this, the rear end of the pin 33 contacts the key member 22, and the front end of the pin 33 contacts the arm 27 b of the reaction force piston 27. As a result, the end surface of the small diameter portion 27a of the reaction force piston 27 is separated from the end surface 12b of the valve plunger 12 facing it, and each member returns to the inoperative position shown in FIG. In this non-operating state, the key member 22 and the valve plunger 12 interlocked with the key member 22 are held at positions advanced with respect to the valve body 3.
[0013]
(Second embodiment)
Next, FIG. 2 shows a second embodiment of the present invention. In the second embodiment, the pin 33 and the guide hole 3b of the first embodiment are omitted, and instead, the rear end of the small diameter portion 27a of the reaction force piston 27 is brought into contact with the key member 22. It is.
That is, a concave portion 27d is formed on the rear side end surface of the small diameter portion 27a of the reaction force piston 27, and the outer peripheral portion of the position where the concave portion 27d is provided is airtightly fitted to the valve body 3 so as to be slidable. are doing. The front end of the valve plunger 12 is slidably fitted in the recess 27d of the reaction force piston 27, so that the front end 12b of the valve plunger 12 faces the bottom of the recess 27d. I am letting. The depth of the concave portion 27d, that is, the axial dimension is set to a predetermined length. Therefore, in the non-actuated state shown in the drawing, the rear side end portion of the small-diameter portion 27a provided with the concave portion 27d is in contact with the key member 22. A gap is maintained between them. That is, in this second embodiment, the valve plunger 12 and the reaction force piston 27 in the non-actuated state are constituted by the key member 22 in contact with the wall surface of the rear shell 2 and the small diameter portion 27a provided with the recess 27d of the reaction force piston 27. The separating means 34 is configured to separate them from each other.
Other configurations are the same as those of the first embodiment described above. Even in the second embodiment having such a configuration, the same effects as those of the first embodiment can be obtained.
In the above embodiment, a brake pedal is used as the operating rod. However, the operating rod may be a manual brake lever used by a physically handicapped person. The present invention can also be applied to a clutch booster, in which case a clutch pedal can be used as an operating rod.
[0014]
【The invention's effect】
As described above, according to the present invention, an unnecessarily large reaction force is not transmitted to the driver during a sudden operation as in the prior art, and a large output necessary during a sudden operation can be obtained with a light pedaling force. The effect is obtained. In addition, although the reaction disk is omitted, the same jumping characteristic as that of the conventional one can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a first embodiment of the present invention.
FIG. 2 is a sectional view showing a second embodiment of the present invention.
FIG. 3 is a characteristic diagram showing a relationship between an input and a pseudo reaction force according to the first embodiment shown in FIG. 1;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Front shell 2 Rear shell 3 Valve body 4 Power piston 6 Constant pressure chamber 7 Transformer chamber 8 Valve mechanism 12 Valve plunger 21 Input shaft 22 Key member 24 Output shaft 26 Pseudo reaction force giving means 27 Reaction force piston 31 Spring 33 Pin 34 Separation means

Claims (4)

A valve body slidably provided in the 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 provided in the valve body. A valve mechanism for switching a communication state of the flow path, a valve plunger constituting a part of the valve mechanism, an input shaft for operating the valve mechanism by moving the valve plunger forward and backward in conjunction with the operating rod, and the valve body A booster with an output shaft advanced by
The output shaft is engaged with the valve body so that the reaction force of the output acting on the output shaft is not transmitted to the valve plunger when the booster is operated, and according to the amount of movement of the input shaft. Pseudo reaction force applying means for applying the pseudo reaction force to the operating rod is provided, and the pseudo reaction force applying means is provided on the rear side by an elastic member disposed in the constant pressure chamber and an elastic force of the elastic member. A reaction force piston that is biased and can come into contact with the valve plunger,
In addition, a separation means for separating the reaction force piston and the valve plunger facing the reaction force piston in a non-operating state of the booster is provided, and the separation means includes a key member engaged with the valve plunger. A reaction force mechanism for a booster, wherein in a non-actuated state, the reaction force piston and the valve plunger are separated from each other by the key member coming into contact with the shell . The valve plunger has a small-diameter portion at a predetermined position in the axial direction, and the key member is engaged with the small-diameter portion of the valve plunger. The key member and the valve plunger have an axial dimension of the small-diameter portion of the valve plunger. The key member can be relatively moved in the axial direction within the range, and the key member is inserted into the insertion hole of the valve body, and can move relative to the valve body in the axial direction within the range of the axial dimension of the insertion hole. A portion of the valve body located on the outer side is in contact with a shell facing the valve body, and a recess is formed in the rear end surface of the reaction force piston. end side is Yes by slidably fitted, said separating means consists of portions of the rear side forming a recess in the key member and the reaction piston, Contact inoperative of the booster The key member is in contact with the shell, and the bottom end of the recess of the reaction force piston is separated from the valve plunger opposite to the key member by the contact of the rear end of the reaction force piston with the key member. The reaction force mechanism of the booster according to claim 1, wherein: The valve plunger has a small-diameter portion at a predetermined position in the axial direction, and the key member is engaged with the small-diameter portion of the valve plunger. The key member and the valve plunger have an axial dimension of the small-diameter portion of the valve plunger. The key member can be relatively moved in the axial direction within the range, and the key member is inserted into the insertion hole of the valve body, and can move relative to the valve body in the axial direction within the range of the axial dimension of the insertion hole. The portion of the valve body located on the outer side is in contact with the shell facing the valve body, and the separation means includes the key member and the key member in contact with the shell when the booster is in an inoperative state. 2. The reaction force mechanism of the booster according to claim 1, further comprising a pin that maintains the key member and the reaction force piston at a predetermined distance when they are separated from each other.   The reaction force piston is slidably fitted to the inner peripheral portion of the valve body from the front side and is opposed to the valve plunger. The rear-side small-diameter portion, the arm portion extending radially outward, and the arm portion A cylindrical portion provided at an end on the outer side, and the elastic member is a spring elastically provided over the cylindrical portion of the reaction force piston and the wall surface of the shell, and the output shaft is attached to the valve body. In addition to being integrally connected, a slit along the axial direction is provided at the rear end portion of the output shaft, and the reaction force piston is formed by passing the arm portion of the reaction force piston through the slit of the output shaft. The reaction force mechanism of the booster according to any one of claims 2 to 3, characterized by being configured to be movable with respect to the output shaft.

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