JPS6237266A - Pressure control device for booster - Google Patents

Abstract

PURPOSE:To improve response and prevent an operator from having unpleasant feeling by overlapping the control for primary and secondary opening and closing means in the performance thereof. CONSTITUTION:A booster mechanism 2 is intended to intensify a stepping force working on a brake pedal 1, with a forward atmospheric pressure chamber 5 continuous to the atmosphere at all times, and an aft control pressure chamber 6 changeable for continuity to a supply source 13 or the atmosphere via the relay valve 12 of a pressure control device 11. This device 11 is fitted with primary and secondary opening and closing means 15 and 16, and the opening and closing of said means 15 and 16 are regulated by a control means 17. And said means 15 and 16 are overlapped with each other in the control of opening and closing, and when said means 15 and 16 are open simultaneously, a pressure fluctuation range P in a pilot chamber 14 becomes small, corresponding to the flow passage area thereof. The control pressure of small pulsation is thereby introduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pressure control device for a booster, and more specifically to a pressure control device for controlling the pressure of pressure fluid supplied to a booster mechanism that constitutes a booster. Regarding a control device.

"Prior Art" Conventionally, as a brake booster, the magnitude of the pedal force applied to the brake pedal is detected by an input detection means, the signal is input to a control device, and this control device controls a pressure control device. A brake fluid pressure is generated in the master cylinder by generating a control pressure corresponding to the magnitude of the pedal force and supplying this control pressure to a control pressure chamber of a booster mechanism linked to the master cylinder. (For example, Japanese Patent Application Laid-Open No. 18874/1983).

According to this type of brake booster, the output characteristics of the booster mechanism can be easily changed by simply changing the control conditions of the pressure control device in the bipedal control device, which increases versatility and improves operation. It becomes possible to change the output characteristics according to the operator's preference, and by inputting signals from a detector that detects the weight and deceleration of a heavy vehicle to the -J2 control device, the driving condition of the vehicle can be changed. Since the pressure control device can be controlled more precisely according to E, it is possible to obtain an ideal braking force according to the driving condition.

"Problems to be Solved by the Invention" By the way, the above-mentioned pressure control device is required to be able to stably obtain a control pressure of a necessary magnitude, and to be able to obtain the stable control pressure quickly. However, no conventionally known pressure control device satisfactorily satisfies such conditions.

For example, as a pressure control device for a brake booster, an electromagnetic on-off valve is provided in a passage communicating between the control pressure chamber of the booster mechanism and a pressure fluid supply source, and the pressure inside the control pressure chamber and this control pressure chamber is An electromagnetic on-off valve is provided in the passage communicating with the discharge part that discharges the fluid, and the electromagnetic on-off valve on the supply side detects the pressure so that the control pressure in the control pressure chamber becomes the required control pressure. An electromagnetic on-off valve on the discharge side can be controlled to open and close.

However, in a pressure control device with such a configuration, since the electromagnetic on-off valve generally has a fast operating speed, there is no problem in terms of responsiveness, but since pressure control is performed by opening and closing control of the pair of on-off valves, pulsation occurs, making it difficult to obtain stable control pressure. Particularly when a small braking force is required, the pressure fluctuation due to the pulsation becomes a relatively large pressure fluctuation with respect to the required control pressure, which causes discomfort to the driver.

In order to improve such a drawback, pressure fluctuations can be reduced by reducing the flow path area of the pair of electromagnetic on-off valves, but in that case, responsiveness will deteriorate.

"Means for Solving the Problems" In view of such circumstances, the present invention uses a pressure control device to generate a control pressure corresponding to the pilot pressure introduced into the pilot chamber, and to apply the control pressure to the booster mechanism described above. a relay valve that supplies the control pressure chamber to the control pressure chamber, a first opening/closing means for communicating and cutting off the pilot chamber and a pressure fluid supply source, and a second opening/closing means for communicating and cutting off the pilot chamber and the discharge section. and the opening/closing operations of the respective opening/closing means are controlled in an overlapping manner.

"Function" According to this configuration, when the output increases, the control pressure can be quickly increased by opening the first opening/closing means on the supply side having a large flow path area.On the other hand, when a constant output is required, the control pressure can be increased quickly. By controlling the opening/closing operations of each opening/closing means so that they overlap with each other, it is possible to obtain a control pressure with smaller pressure fluctuations than when controlling them without overlapping them, which improves responsiveness. It becomes possible to obtain excellent and stable control pressure.

``Embodiment'' The present invention will be described below with reference to the illustrated embodiment. In FIG. This booster mechanism 2 includes a shell 3 as a sealed container, a power piston 4 provided inside the shell 3 so as to be able to move forward and backward, and a power piston 4 that moves inside the shell 3 between an atmospheric pressure chamber 5 at the front and an atmospheric pressure chamber 5 at the rear. A control pressure chamber 6 and a diaphragm 7 are provided.

The cylindrical shaft portion 4a of the power piston 4 protrudes through the shell 3 to the rear side while keeping the shell 3 airtight, and is linked to the brake pedal l via an input shaft 8 whose tip is pivotally supported on the power piston 4. The power piston 4 is normally held in a retracted, non-operating position as shown in the figure by a return spring 9.

An output shaft 10 is integrally connected and fixed in front of the power piston 4, and this output shaft 10 is interlocked with a master cylinder (not shown) attached to the front part of the shell 3.

”-The atmospheric pressure chamber 5 at the front of the booster mechanism 2 is always in communication with the atmosphere through an opening provided in the shell 3, and the control pressure chamber 6 at the rear constitutes the pressure control device 11 of the present invention. Communication can be switched to a compressed air supply source 13 or the atmosphere via a relay valve 12. The relay valve 12 generates a control pressure corresponding to the pilot pressure introduced into the pilot chamber 14 as described later, and supplies the control pressure to the control pressure chamber 6 of the booster mechanism 2. .

Further, the pressure control device 11 includes the pyro chamber 1
4 and the supply source 13.
5, and - a second opening/closing means 16 for communicating and blocking the pilot chamber 14 and the atmosphere as an exhaust section. These opening/closing means 15 and 16 are controlled to open and close by a control device 17 equipped with a computer.
The control device 17 detects the input applied to the input shaft 8 with an input detection means 18 such as a load cell, and detects the pilot pressure in the pilot chamber 14 with a pressure detection means 19, and controls each opening/closing means 15 and 16. control,
Pyro 7+' positive pressure corresponding to the input value can be generated in the pilot chamber 14.

However, the relay valve 12 has a nozzing 21 consisting of three members in which a through hole 20 is vertically bored, and a housing 21 formed at a stepped portion by enlarging the diameter of the lower middle part of the through hole 20. a plunger 2 which is slidably fitted into the through hole 20 and has a second valve seat 23 formed at its lower end;
4. Then, a cylindrical valve body 25 is slidably fitted into the lower part of the through hole 20, and the valve body 25 and the no.
The valve body 2 is moved by a spring 26 loaded between it and the housing 21.
5 is urged upward so as to seat on each valve seat 22, 23.

Therefore, the valve body 25 includes a first seat portion 30 that seats on the first valve seat 22 and a second seat portion 3 that seats on the second valve seat 23.
1, and the booster mechanism is connected to the booster mechanism through a control passage 34 consisting of a lateral passage 32 and a conduit 33 formed in the nozzle 21 at an intermediate portion between the first seating part 30 and the second seating part 31. It communicates with the control pressure chamber 6 of No. 2.

Further, the above-mentioned pressure fluid supply source 1 is provided through a supply passage 37 consisting of a lateral passage 35 and a conduit 36 formed in the housing 21 on the radially outward side of the first seating part 30.
3, and is controlled via a discharge passage 40 consisting of a passage 38 formed in the shaft portion of the valve body 25 radially inward from the second seating portion 31 and a longitudinal passage 38 formed in the housing 21. The pressure chamber 6 is connected to a discharge section for discharging the pressure fluid in the pressure chamber 6, that is, to the atmosphere.

Further, the valve body 25 has a stepped portion 41 at the intermediate portion by making the diameter smaller from the intermediate portion downward, and a space including this stepped portion 41 is separated from the valve body 25 and /\Using 21.
The supply passage 37 is separated from the discharge passage 40 by a diaphragm-shaped seal member 42 stretched between the valve body 25 and a ring-shaped seal member 43 provided in the housing 21 and slidably in contact with the lower part of the outer peripheral surface of the valve body 25. It is formed as a pressure chamber 44.

The pressure chamber 44 is communicated with the control passage 34 through a horizontal passage 45 and a vertical passage 46 formed in the housing 21, and the pressure receiving area of the stepped portion 41 and the first seating portion of the valve body 25 are connected to each other. 30 and the second seating portion 3] are made equal, the valve body 2
The control pressure applied to 5 is balanced.

Next, a piston 50 is integrally formed at the upper end of the plunger 24 and is slidably fitted in the through hole 20 in an airtight manner.
The pilot chamber 14 and the pressure chamber 51 described above are each partitioned. The lower pressure chamber 51 is located in the housing 2.
The control passage 34 is communicated with the control passage 34 through a passage 52 formed at 1.

A spring 53 housed in the pressure +51 is installed between the piston 50 and the housing 21, and this spring 53
holds the piston 50 at the upper end position when the relay valve 12 is inactive. In this state, the piston 5
0 is also located at the rising end, the second valve seat 23 and the valve body 25 are separated from each other, and the valve body 25 is seated on the first valve seat 22 due to the elastic force of the spring 26. Therefore, the control pressure chamber 6 of the booster mechanism 2 communicates with the atmosphere via the control passage 34, the gap between the second valve seat 23 and the valve body 25, and the discharge passage 40.

On the other hand, the pilot chamber 14 includes a passage 54 formed in the lX housing 21, a conduit 55, and the first opening/closing means 1 described above.
5 to the supply source 13, and branched from the conduit 55 to communicate with the atmosphere via the second opening/closing means 16. In this embodiment, each opening/closing means 15
．． 16 each consist of one electromagnetic on-off valve.

In the above configuration, in a non-operating state, that is, a state where no pedal force is applied to the brake pedal 1, the control device 1
7 detects its state by the input detection means 18, and the first
The opening/closing means 15 is closed and the second opening/closing means 16 is opened to communicate the pilot chamber 14 with the flame. In this state, as described above, the control pressure chamber 6 of the booster mechanism 2 is connected to the control passage 34.
, the gap between the second valve seat 23 and the valve body 25 and the discharge passage 40
The power piston 4 is also held in a non-operating position by the return spring 9 because there is no pressure difference between the front and rear sides of the power piston 4 .

When the brake pedal 1 is depressed in this state and the pedal force is transmitted to the input shaft 8, the pedal force is detected by the input detection means 18, and the control device 17 closes the second opening/closing means 18 and closes the first opening/closing means 15. It opens to supply pressure fluid into the pilot chamber 14.

When pressure fluid is introduced into the pilot chamber 14, the piston 50 and the plunger 24 integrated therewith are displaced downward, so that the second valve seat 23 and the valve body 25 are seated, and the control pressure chamber 6 After cutting off the communication with the atmosphere, the valve body 25
is moved downward against the spring 26, so the valve body 25 is removed from the first valve seat 22. As a result, pressure fluid is supplied from the supply source 13 into the control pressure chamber 6 of the booster mechanism 2 through the supply passage 37, the gap between the valve body 25 and the first valve seat 22, and the control passage 34, so that the power piston A fluid pressure difference is generated before and after the power piston 4, and the power piston 4 is moved forward against the elastic force of the return spring 9.

The pressure introduced into the pilot chamber 14 is detected by a pressure detection means 18, and when the pressure reaches a pressure corresponding to the input, the control device 17 closes the first opening/closing means 15. On the other hand, the pressure in the control pressure chamber 6 is
2 into the pressure chamber 51 and urges the piston 50 upward. As a result, the plunger 24 moves upward, so that the valve body 25 is seated on the first valve seat 22 and the second valve seat 23 and the valve body 25 are also seated. However, since it takes time, the pressure in the pilot chamber 14 becomes slightly higher than the target pressure. Then, the second opening/closing means 16 is opened to reduce the pressure in the pilot chamber 14. Furthermore, if the pressure in the pilot chamber 14 drops too much, the control device 17 again opens the first opening/closing means 15 and closes the second opening/closing means 16 to supply pressurized fluid to the pilot chamber 14.

At this time, in this embodiment, the opening/closing operations of the first opening/closing means 15 and the second opening/closing means 16 are controlled to overlap with each other, so that the pressure fluctuations in the pilot chamber 14 can be controlled by Therefore, pressure fluctuations in the control pressure chamber 6 are made small.

That is, as shown in FIG.
．． When the opening and closing means 15 and 16 are controlled to open and close alternately without overlapping each other, the pressure fluctuation width P in the pilot chamber 14 increases, but as shown in FIG. , when the first opening/closing means 15 and the second opening/closing means 16 are turned on at the same time, the pilot chamber 1 corresponds to the flow path area of each opening/closing means 15 and 16.
Since the rate of pressure increase in the pilot chamber 14 does not decrease or the pressure decreases, the pressure fluctuation range p in the pilot chamber 14 becomes smaller.

Therefore, a small pulsating control pressure is introduced into the control pressure chamber 6 in response to the input applied to the input shaft 8 and in accordance with the mutually overlapping opening and closing operations of the respective opening and closing means 15 and 16. become. As a result, the power piston 4 and the output shaft 1o integrated therewith are moved forward with an output corresponding to the input, and brake fluid pressure is generated in a master cylinder (not shown) linked to the output shaft 10 to perform a braking action. It becomes like this.

In this way, when the pressure increases, the first opening/closing means 15 having a large flow path area can be opened to quickly cause the booster mechanism 2 to generate an output, and the control pressure can be maintained at the required pressure corresponding to the input value. In such a case, pressure fluctuations can be reduced by mutually overlapping opening/closing control of the opening/closing means 15, 16, resulting in good responsiveness and preventing discomfort to the operator.

In the above embodiment, when the control pressure reaches the required pressure corresponding to the input value, the opening/closing means 15 and 16 are continuously controlled to open and close in a mutually overlapping state. It is not limited. For example, when the control pressure reaches the required pressure corresponding to the input value,
Closing the opening/closing means 15 and opening/closing the pilot chamber 14
5.16, and when the pressure in the pilot chamber 14 drops by more than a predetermined value with respect to the input value, each opening/closing means 15.16 is momentarily opened only once in a mutually overlapped state. You may also do so. Even in this case, the pressure rise is smaller than the pressure increase when only the first opening/closing means 15 is opened once.
It is clear that since two rises can be obtained, the width of pressure fluctuation can be reduced.

Furthermore, each opening/closing means is not limited to a single electromagnetic opening/closing valve; for example, W
The L electromagnetic on-off valves may be connected in parallel. moreover,
Of course, the control pressure may be determined comprehensively by inputting various conditions such as the loading state of the vehicle and the deceleration into the control device 17.

"Effects of the Invention" As described above, according to the present invention, it is possible to obtain an output of a boosting mechanism that is excellent in responsiveness and stable.

[Brief explanation of the drawing]

Fig. 1 shows one embodiment of the present invention, and is a system diagram with a cross-sectional view of the main parts, and Fig. 2 is a diagram illustrating the pressure fluctuation width P when the opening/closing operations of each opening/closing means are controlled without overlapping. ,
FIG. 3 is a diagram illustrating the pressure fluctuation range P according to the present invention. 1...Brake pedal 2...Boosting mechanism 3...Shell 4...Power piston 6...Control pressure chamber 8...Input shaft 11...Pressure control device
12... Relay valve 13... Supply source 14.
...Pilot room 15...First opening/closing means 16...
-Second opening/closing means 17...control device 18...
Input detection means Fig. 2 Fig. 3

Claims (1)

[Claims] A pressure control device for a booster that detects an input applied to an input shaft and supplies a control pressure based on the input value to a control pressure chamber of a booster mechanism to generate an output, the pressure control device comprising: A relay valve that generates a control pressure corresponding to the pilot pressure introduced into the pilot chamber and supplies the control pressure to the control pressure chamber of the booster mechanism, and communicates and shuts off the pilot chamber and the pressure fluid supply source. and a second opening/closing means for communicating and cutting off the pilot chamber and the discharge section, and controlling the opening/closing operations of each of the opening/closing means in an overlapping manner. Pressure control device of force device.