JPH10167045A - Automatic brake booster - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a brake from being left applied by advancing a valve plunger to release the sticking of a sleeve at an abutting section, even if the sleeve sticks to a valve body. SOLUTION: A valve mechanism 5 comprises an atmospheric valve seat 7 provided to a sleeve 6, a vacuum valve seat 11 provided to a valve plunger 10, a valve element 13 which sits on both valve seats 7, 11 from the front side and a loaded spring 15 which forces the atmospheric valve seat 7 and the valve element 13 to be seated at the time of disuse. A solenoid 16, when it is energized, moves back the sleeve 6 toward the rear side against the force of the loaded spring 15 to separate the atmospheric valve seat 7 from the valve element 13 and let the vacuum valve seat 11 and the valve element 13 seated. In addition, the valve plunger 10 is provided with a contactor 34 so that the valve plunger 10 when it advances, touches then advances the sleeve 6 which is in the moved back position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake booster used for a vehicle brake, and more particularly, to an automatic brake booster having an automatic braking function.

[0002]

2. Description of the Related Art A conventional 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 mechanism that has a valve plunger that moves forward and backward in conjunction with the input shaft, and that controls opening and closing of the flow path in accordance with the forward and backward movement of the valve plunger. The valve mechanism is usually provided on the valve body, an annular vacuum valve seat formed on the valve plunger toward the rear side, an annular air valve seat formed on the valve body toward the rear side, and provided on the valve body. A valve body which is urged by a spring and seats on both valve seats from the rear side. In addition, conventionally, when energized, the valve plunger is advanced to the front side in the valve body which is on the front side of the valve plunger, and the atmospheric valve seat is separated from the valve body to open the atmospheric valve, and There is also known an automatic brake booster provided with a solenoid for seating a vacuum valve seat and a valve body. In such an automatic brake booster, if the solenoid is excited without depressing the brake pedal, the atmosphere valve can be opened and the atmosphere can be introduced into the transformation chamber, so that a braking action can be obtained.

[0003]

However, in the conventional automatic brake booster, if the valve plunger sticks at a position advanced by the solenoid for some reason, the booster is provided even if the solenoid is demagnetized. There is a drawback in that the operation of the device cannot be released, and the brake remains effective so that the vehicle cannot be moved. The present invention has been made in view of such circumstances, and provides an automatic brake booster that can easily release the operation of the booster and prevent the brake from being kept effective.

[0004]

That is, the present invention provides 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 partitioned before and after the power piston. A brake booster having a valve plunger that is moved forward and backward in conjunction with the input shaft, and a valve mechanism that performs opening and closing control of the flow path in accordance with the forward and backward movement of the valve plunger. A sleeve slidably provided on the valve body, an annular atmospheric valve seat provided on the sleeve toward the front side, an annular vacuum valve seat provided on the valve plunger toward the front side, and A valve body that is provided and is urged by a poppet return spring and seats on both valve seats from the front side, and urges the sleeve toward the front side to increase the brake boost And a biasing spring that seats the atmospheric valve seat and the valve body when the device is not operated, and further, when the inner peripheral surface of the valve body on the rear side of the valve mechanism is excited, the sleeve is energized. A solenoid is provided for retracting the atmospheric valve seat from the valve body by retreating to the rear side against the elastic force of the biasing spring, and providing a solenoid for seating the vacuum valve seat and the valve body. And a contact portion for contacting the sleeve at the retracted position when the valve plunger is advanced to advance the sleeve.

[0005]

According to the above-described structure, when the brake booster is not operated, the atmosphere is not introduced into the variable pressure chamber because the air valve seat and the valve body are seated. It will not be activated. When the solenoid is excited from this non-operating state, the sleeve is retracted to release the air valve seat from the valve body, and the vacuum valve seat and the valve body are seated. Thus, even if the brake pedal is not depressed, the brake booster can be operated to obtain the braking action.
In this state, if the sleeve sticks to the valve body at the position where the sleeve is retracted, the brake remains effective. In this case, the brake plunger is depressed to advance the valve plunger and the contact portion. Thus, the contact portion can be brought into contact with the sleeve and can be forcibly advanced, whereby the stick of the sleeve can be released to release the braking action.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiment. A cylindrical valve body 2 is slidably provided in a shell 1 of a brake booster, and a rear end cylindrical portion 2A on the rear side of the valve body 2. Is slidably protruded from the cylindrical portion 1A of the shell 1 to the outside. A substantially dish-shaped power piston 3 is connected to the outer periphery of the valve body 2.
The inside of the shell 1 is divided into a constant pressure chamber A on the front side and a variable pressure chamber B on the rear side by extending the diaphragm 4 on the back surface of the power piston 3. A valve mechanism 5 for switching a fluid circuit between the constant pressure chamber A and the variable pressure chamber B is provided in the valve body 2. This valve mechanism 5
A sleeve 6 made of a magnetic material slidably provided in the inner peripheral surface of the valve body 2 while maintaining airtightness; and an annular atmospheric valve seat 7 formed at the front end of the sleeve 6 toward the front. A valve plunger 10 which is provided in the valve body 2 so as to be able to move forward and backward and is linked to the input shaft 8; A valve seat 11, a substantially cylindrical valve body 13 seated on the valve seats 7, 11 from the front side by the elastic force of a poppet return spring 12;
A valve return spring 14 for urging the valve plunger 10 and the input shaft 8 rearward, an urging spring 15 for urging the sleeve 6 frontward, and further urging the sleeve 6 when excited. And a solenoid 16 that is displaced rearward against the elastic force of the spring 15.

The sleeve 6 is slidably fitted in a small-diameter hole 2a formed at an intermediate position between the end cylindrical portion 2A of the valve body 2 and the outer peripheral portion of the sleeve 6 and the end cylindrical portion 2A. The airtightness of that portion is maintained by the annular seal members 18 provided on the outer peripheral portion of the device. Atmospheric valve seat 7 is attached to the tip of outer cylindrical portion 6a of sleeve 6.
And an engaging portion 6b is formed by projecting radially outward from a distal end portion of the outer cylindrical portion 6a.
Is disposed in the middle diameter hole 2b of the end cylindrical portion 2A so as to be able to move forward and backward. Normally, the resilient force of the urging spring 15 causes the engaging portion 6b to abut on the step between the small-diameter hole 2a and the medium-diameter hole 2b to prevent the sleeve 6 from being pulled out to the front side. At the same time, when the booster is not operated, the valve 13 is seated on the atmospheric valve seat 7 so that the portion can be sealed. On the other hand, when the solenoid 16 is excited, the sleeve 6 is displaced rearward so that the atmospheric valve seat 7 can be separated from the valve 13.

Next, a large-diameter portion 10A is formed from a substantially central portion of the valve plunger 10 to the rear side, and a circular thin wall portion 10a extending radially outward is formed at a front portion of the large-diameter portion 10A. The outer peripheral portion of the wall portion 10a is protruded toward the front side, and the tip of the annular protruding portion 10b is the vacuum valve seat 11 described above. In addition, the wall 10
An annular groove 10c is formed in the large-diameter portion 10A on the rear side of the valve body a. The key member 20 inserted into the radial hole of the valve body 2 is engaged with the annular groove 10c so that the valve plunger 10 is Pulling out of the valve body 2 is prevented. The valve plunger 10 is biased rearward by a valve return spring 14 elastically mounted between the holder 21 fitted on the front side of the valve body 2 and the wall 10a. Further, the cylindrical valve body 13 made of an elastic body is disposed toward the rear side so as to face the valve seats 7 and 11, and has a thick front end portion which is an end on the front side. The airtightness is maintained and fixed by the holder 21 fitted in the valve body 2. On the other hand, a reinforcing plate 2 is provided on the rear side of the rear end face of the valve body 13.
And a poppet return spring 12 mounted between the reinforcing plate 22 and the holder 21.
This biases the rear end of the valve body 13 toward the valve seats 7 and 11.

An atmosphere valve 23 is constituted by the atmosphere valve seat 7 provided on the valve body 2 and the valve body 13 which comes in contact with and separates from the atmosphere valve seat 7. The air passage 24 is formed by a passage 25 formed in the sleeve 6 and a gap between the inner peripheral surface of the end tubular portion 2A and the outer peripheral surface of the solenoid 16. Filter 26 provided in section 2A
Is in communication with the atmosphere through In addition, the vacuum valve seat 11
A vacuum valve 27 is constituted by the valve body 13 and the valve body 13 which comes in contact with and separates from the valve body.
And The constant pressure passage 28 is always in communication with the constant pressure chamber A via an axial passage 29 formed in the holder 21. The constant pressure chamber A communicates with an intake manifold (not shown) of the engine via a negative pressure introducing pipe 30 provided in the shell 1, whereby a constant negative pressure is introduced into the constant pressure chamber A. Further, a space between the atmospheric valve 23 and the vacuum valve 27 is a variable pressure passage 32. The variable pressure passage 32 is formed in the valve body 2 through a through hole 6c formed in the sleeve 6 and the through hole 6c. It is formed by the provided passage and is always in communication with the transformer chamber B. The key member 21 is penetrated into the through hole 6c of the sleeve 6 so that the sleeve 6 can be displaced in the axial direction without receiving the interference of the key member 21.

The solenoid 16 is housed in a case 33 fitted and fixed in the end cylindrical portion 2A of the valve body 2, and the shaft of the case 33 slides the large diameter portion 10A of the valve plunger 10. It is movably held.
The large-diameter portion 10A is provided with an annular contact portion 34 at a position rearward of the sleeve 6.
When the input shaft 8 and the large-diameter portion 10A of the valve plunger 10 are advanced in a state where the sleeve 6 is displaced rearward by the solenoid 16, the sleeve 6 comes into contact with the sleeve 6 to reduce the suction force of the solenoid 16. The sleeve 6 can be advanced against it. Further, a wiring 35 from the solenoid 16 is drawn out through the inside of the atmosphere passage 24.

A small-diameter portion 10B formed on the front side of the large-diameter portion 10A of the valve plunger 10 is slidably fitted on the shaft of the holder 21, and a plate plunger 36 is fitted on the front side of the small-diameter portion 10B. And a reaction disk 37 are sequentially arranged. The above plate plunger 3
6 is slidably fitted to the shaft of the holder 21;
On the other hand, the reaction disk 37 is provided in a recess formed at the base of the output shaft 38. And the output shaft 38
Is slidable with respect to the valve body 2 by slidably fitting the front end surface of the holder 21 in the recess, and the output shaft 38 is mounted outside the shell 1 in the drawing. Not linked to the master cylinder piston. A return spring 3 is provided between the inner surface of the shell 1 and the front end surface of the valve body 2.
9, the valve body 2 is normally held at the non-operating position shown in the figure.

In the above configuration, when the brake booster shown in FIG. 1 is not operated, the solenoid 16 is demagnetized, and the sleeve 6 is held at the forward end position by the resilient force of the biasing spring 15. . In this state, the valve body 13 is seated on the atmosphere valve seat 7 at the tip of the sleeve 6 by the resilience of the poppet return spring 12 to close the atmosphere valve 23, and the valve plunger is resilient by the resilience of the valve return spring 14. The input shaft 10 and the input shaft 8 are displaced rearward, whereby the vacuum valve seat 11 is separated from the valve body 13 and the vacuum valve 27 is opened. Therefore, the constant pressure passage 2
8 and the variable pressure passage 32 communicate with each other.
The constant-pressure chamber A and the variable-pressure chamber B are communicated with each other.

When the brake pedal (not shown) is depressed from the inoperative state and the input shaft 8 is moved to the left, the valve plunger 10 is thereby moved to the valve return spring 14.
The vacuum valve seat 11 is pressed against the valve body 13 and the vacuum valve 27 is closed, and then the valve body 13 is separated from the atmospheric valve seat 7 and the atmospheric valve 23 is opened. be opened. Thereby, the communication between the variable pressure chamber B and the constant pressure chamber A is cut off, and the variable pressure passage 32 and the atmosphere passage 24 are connected.
Atmosphere is introduced into the transformation chamber B. As a result, a pressure difference occurs before and after the power piston 3, and the power piston 3, the valve body 2, and the output shaft 38 are advanced, so that a braking action can be obtained as in the conventional brake booster. At this time, the contact portion 3 provided on the valve plunger 10
4 does not come into contact with the sleeve 6 at the forward end position.

On the other hand, when the brake booster is operated as an automatic brake booster in the non-operating state, the solenoid 16 may be excited. This allows
Since the sleeve 6 is retracted against the elastic force of the urging spring 15, the atmospheric valve seat 7 of the sleeve 6 and the valve body 13 seated thereon are displaced rearward, and the valve body 13 Is seated on the vacuum valve seat 11 and the vacuum valve 27 is closed. When the sleeve 6 is further retracted, the atmosphere valve seat 7 is separated from the valve body 13 and the atmosphere passage 24 is opened. as a result,
Since the communication between the constant pressure chamber A and the variable pressure chamber B is cut off and the variable pressure chamber B is connected to the atmosphere via the variable pressure passage 32 and the atmosphere passage 24, even if the brake pedal is not depressed,
A braking action can be obtained in the same manner as in the above-described brake pedal depressed state. Here, the diameter of the atmosphere valve seat 7 is D,
Assuming that the diameter of the seal 40 between the valve plunger 10 and the sleeve 6 is d, the difference between the variable pressure chamber B and the atmospheric pressure is P, the set load of the biasing spring 15 of the sleeve 6 is Fsp, and the force generated by the solenoid 16 is Fso, The following relationship holds: Fso = Fsp + π ｛P (D ² −d ² )｝ ÷ 4 Therefore, the current flowing through the solenoid 16 is controlled, and
By changing so, the difference P between the atmospheric pressure and the vacuum pressure can be changed arbitrarily, and an arbitrary braking force can be obtained. When releasing the automatic braking action from this state, if the solenoid 16 is demagnetized,
Since the sleeve 6 is returned to the original forward position by the resilient force of the biasing spring 15, the atmospheric valve 23 is closed and the vacuum valve 27 is opened, and the brake booster returns to the original non-operating state. I do.

By the way, when the brake booster is operated as the above-mentioned automatic brake booster, even if the solenoid 16 is demagnetized, the sleeve 6 sticks to the valve body 2 and remains at the retracted position. If it does, the automatic brake state cannot be released and the brake remains in the applied state. To release the braking action at this time, the brake pedal may be depressed. Then, the valve plunger 10 is input via the input shaft 8.
Is moved left, and the contact portion 34 contacts the sleeve 6 located at the retracted position, and the sleeve 6 can be forcibly advanced, so that the stick can be released. Further, fuel may enter the constant pressure chamber A communicating with the intake manifold of the engine, and when the wiring 35 of the solenoid 16 is drawn out through the constant pressure chamber A, the wiring 35 is damaged. If a short circuit occurs, there is a risk of explosion or fire.
Is drawn out to the outside through the atmosphere passage 24, there is no such fear. Also, the solenoid 16 is connected to the wiring 3
When 5 is drawn out through the constant-pressure chamber A, it is necessary to shut off the atmosphere and vacuum so as to supply electricity, but this is not necessary in the present invention. Furthermore, if the driver desires a higher braking force while the weak automatic brake is being operated, a higher arbitrary braking force can be obtained by depressing the brake pedal.

[0016]

As described above, according to the present invention, when the sleeve slidably provided in the valve body sticks with the valve body, the brake pedal is depressed to thereby make the contact portion provided on the valve plunger. As a result, the stick can be released by forcibly advancing the sleeve, so that the effect of preventing the brake from remaining effective can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

[Explanation of symbols]

 2 ... Valve body 3 ... Power piston 5 ... Valve mechanism 6 ... Sleeve 7 ... Atmospheric valve seat 8 ... Input shaft 10 ... Valve plunger 11 ... Vacuum valve seat 13 ... Valve 16 ... Solenoid 23 ... Atmospheric valve 27 ... Vacuum valve 34 ... This Contact 35: Wiring A: Constant pressure chamber B: Transformation chamber

Claims (3)

[Claims] 1. 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 defined before and after the power piston. And a valve mechanism for controlling the opening and closing of the flow path in accordance with the advance and retreat of the valve plunger. The valve booster is slidably provided on the valve body. A sleeve, an annular atmospheric valve seat provided on the sleeve toward the front side, an annular vacuum valve seat provided on the valve plunger toward the front side, and provided on the valve body and urged by a poppet return spring. And the valve body seated on the two valve seats from the front side, and the sleeve is urged to the front side, so that the air valve seat and the valve are closed when the brake booster is not operated. And a biasing spring for seating the sleeve on the inner peripheral surface of the valve body on the rear side of the valve mechanism. Side, the above-mentioned atmospheric valve seat is separated from the valve body, and a solenoid for seating the above-mentioned vacuum valve seat and the valve body is provided, and the valve plunger is moved backward when the valve plunger is advanced. An automatic brake booster comprising a contact portion for contacting and advancing a sleeve at a position. 2. A space outside the atmosphere valve constituted by the atmosphere valve seat and the valve body seated thereon is an atmosphere passage communicating with the atmosphere, and the vacuum valve seat and the valve body seated thereon are provided. And a space inside the vacuum valve is a constant pressure passage communicating with the constant pressure chamber, and a space between the atmospheric valve and the vacuum valve is a variable pressure passage communicating with the variable pressure chamber. The automatic brake booster according to claim 1, wherein: 3. The automatic brake booster according to claim 1, wherein a wiring is drawn out of the solenoid through an atmosphere passage.