JPS6237263A - Pressure control method for booster - Google Patents

Abstract

PURPOSE:To prevent an operator from having unpleasant feeling by supplying the control chamber of a booster mechanism with the higher pressure of primary and secondary control pressures. CONSTITUTION:The atmospheric pressure chamber 5 of a booster mechanism 2 is continuous to the atmosphere at all times and a control pressure chamber 6 is changeable for continuity to either the supply source 12 of compressed air or the atmosphere via a pressure control device 11. The rotation of a servo motor 68 is regulated by a control device 13. A primary pressure chamber 67 is continuous to said supply source 12 via a passage 71, a conduit 72 and a primary solenoid valve 73, and branched from the conduit 72 for continuity to the atmosphere via a secondary solenoid valve 74 and said valves 73 and 74 are regulated for opening and closing by the control device 13. And the servo motor 68 makes available a secondary control pressure having more stability than a primary control pressure, and it is possible to make the booster mechanism 2 generate a stable output on the basis of an input value.

Description

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

"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. 188748/1983).

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 E control device, which increases versatility and improves driver comfort. It is possible to change the output characteristics according to the preference of the vehicle, and by inputting signals from a detector that detects the weight and deceleration of the vehicle to the above-mentioned control device, the pressure control device can be adjusted according to the driving state of the vehicle. can be controlled more precisely, making it possible to obtain ideal braking force according to driving conditions.

"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, a first 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 control pressure chamber and this control pressure chamber are provided with a first electromagnetic on-off valve. A second electromagnetic opening/closing valve is provided in a passage communicating with a discharge section for discharging the pressure fluid, and while detecting the pressure so that the control pressure of the control pressure chamber becomes a necessary control pressure, the first It is conceivable to use an electromagnetic on-off valve and a second electromagnetic on-off valve that can be controlled to open and close.

However, in a pressure control device with such a configuration, the electromagnetic on-off valve generally has a fast operating speed, so there is no problem in terms of responsiveness, but since the pressure control is based on the opening/closing control of a pair of electromagnetic on-off valves, the control pressure may pulsate. This makes 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.

On the other hand, there are other pressure control devices in which a servo motor is incorporated into a pressure control valve with an appropriate configuration that can obtain a constant control pressure, and the servo motor is configured so that the control pressure by the pressure control valve can be varied. It is possible to use With this kind of pressure control device, it is easy to stably obtain the necessary control pressure, but servo motors generally have poor responsiveness compared to electromagnetic on-off valves, and in order to improve responsiveness, it is expensive. There was a disadvantage that a large servo motor had to be used.

In view of such circumstances, the present invention uses the detected input value as an element to determine whether or not the boosting mechanism is required to rapidly increase the output, and to increase the output rapidly. When an increase is required, a highly responsive solenoid valve quickly obtains a first control pressure lower than the control pressure based on the input value, and
A stable second control pressure is obtained by the servo motor, and the higher control pressure of the first control pressure and the second control pressure is supplied to the control pressure chamber of the booster mechanism.

On the other hand, when the booster mechanism is not required to rapidly increase its output, the first control pressure obtained by the solenoid valve is not supplied to the control pressure chamber of the booster mechanism, and the first control pressure is obtained by the servo motor. A stable second control pressure is supplied to the control pressure chamber.

"Function" According to such a control method, when the above-mentioned rapid output increase is required, the first control pressure is obtained by a highly responsive solenoid valve at the initial stage of operation, and the output is promptly output to the booster mechanism. is generated, and subsequently a stable second control pressure higher than the first control pressure is obtained by the servo motor, thereby making it possible to cause the booster mechanism to generate a stable output based on the input value. The fact that a rapid output increase is required does not differ from the fact that a large output is generally required, so pulsations occur in the control pressure supplied to the control pressure chamber due to the operation of the solenoid valve at the initial stage of the operation. However, since the pressure fluctuations are relatively small with respect to the control pressure that produces a large output, it is possible to prevent discomfort to the operator, and therefore it is possible to obtain a control pressure that is excellent in responsiveness and stable.

On the other hand, if a rapid increase in output is not required, the second
It is clear that even if the booster mechanism generates output using control pressure, it will not cause discomfort to the operator due to poor response, and even if a rapid increase in output is not required, a small output Even if such a small output is required, the stable second control pressure obtained by the servo motor is supplied to the control pressure chamber of the booster mechanism. Therefore, the operator does not feel discomfort due to pulsation.

``Embodiment'' The present invention will be described below with reference to the illustrated embodiment. In FIG. 1, 1 is a brake pedal (not shown) pivotally supported on the vehicle body, and 2 is a boosting mechanism that boosts the pedal force applied to the brake pedal l. , this boosting mechanism 2 includes a shell 3 as a sealed 6T, a power piston 4 provided in 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 in front and an atmospheric pressure chamber 5 in the rear. A control pressure chamber 6 and a diaphragm 7 are provided.

The cylindrical shaft portion 4a of the power piston 4 is interlocked with the brake pedal l via an input shaft 8 which protrudes through the shell 3 to the rear side while keeping the shell 3 airtight and has its tip pivoted to 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 in 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 in the rear is connected to the atmosphere through a pressure control device 11 according to the present invention. It is connected to the compressed air supply source 12 or to the atmosphere and is connected to the air. This pressure control device M11 is controlled by a control device 13 equipped with a microcomputer.
The input applied to the input shaft 8 is detected by the input detection means 14 such as a load cell, and the pressure in the first pressure chamber 67 of the pressure control device 11, which will be described later, is detected by the pressure detector 7.
5, and when not in operation, the control pressure chamber 6 of the booster mechanism 2 is communicated with the atmosphere by the pressure control device ¥11, and when in operation, the control pressure is controlled according to the input applied to the input shaft 8. It is designed to be supplied into the chamber 6.

However, the pressure control device 11 has a through hole 2 in the vertical direction.
A valve mechanism 19 is provided in a housing 21 consisting of five members having a diameter of 0 perforated therein. The plunger 24 is provided with a first valve seat 22 and a plunger 24 that is slidably fitted into the center of the through hole 20 and has a second valve seat 23 formed at its lower end. A cylindrical valve body 25 is slidably fitted into the lower part of the through hole 20, and a spring 26 elastically loaded between the valve body 25 and the housing 21 allows the upper end surface of the valve body 25 to be fixed to each valve. It is urged upward so that it is seated on the seats 22 and 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 2 is controlled through a control passage 34 consisting of a lateral passage 32 and a conduit 33 formed in the housing 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.

Further, a radially outward side of the intermediate portion is communicated with the pressure fluid supply source 12 described above via a supply passage 37 formed in the /X housing 21 and formed of a lateral passage 35 and a conduit 36, and furthermore, the intermediate portion radially inward than E
A discharge section for discharging the pressure fluid in the control pressure chamber 6 is communicated with the atmosphere through a discharge passage 40 consisting of a passage 38 formed in the shaft portion of the valve body 25 and a vertical passage 39 formed in the housing 21. .

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 created between the valve body 25 and the housing 21. The supply passage 37 is connected to the supply passage 37 by the stretched diaphragm-shaped seal portion 42 and the ring-shaped seal member 43 provided in the housing 21 and in sliding contact with the lower part of the outer peripheral surface of the valve body 25.
It is formed as a pressure chamber 44 separated from the exhaust passage 40 and the exhaust passage 40 .

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 surface of the stepped portion 41 and the first By making the pressure-receiving area equal in the intermediate portion between the seating portion 30 and the second seating portion 31, the valve body 2
The control pressure applied to 5 is balanced.

Next, a second piston 5 is provided in the middle part of the plunger 24.
0 is fixed, and a diaphragm 51 is stretched between the second piston 5o and the housing 21 to define an atmospheric pressure chamber 52 and a second pressure chamber 53 above and below, respectively. The upper atmospheric pressure chamber 52 is communicated with the atmosphere through a passage 54 formed in the housing 21, and the lower second pressure chamber 53 is communicated with the atmosphere through a passage 55 formed in the housing 21.
It communicates with the inside of the control passage 34 via.

A spring 56 housed in the second pressure chamber 53 is resiliently mounted between the second piston 50 and the housing 21, and when the pressure control device 11 is inactive, the spring 56 is held at the rising end position. In this state, the plunger 24 integrated with the second piston 50 is also located at the rising end, and the second valve seat 23 and the valve body 25 are separated from each other. Since it is seated on the seat 22, 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 4θ
It communicates with the atmosphere through.

Further, a support member 57 is slidably fitted to the upper end of the plunger 24, and the large diameter portion 5 of the upper end of the plunger 24
8 prevents the support member 57 from coming out of the plunger 24. An elastic body 58 made of a spring is mounted between the support member 57 and the second piston 50,
Normally, the support member 57 is held at the raised end position in contact with the upper large diameter portion 58 by the elastic force of the elastic body 5S.

A first piston 65 is interlocked with the support member 57, and a diaphragm 86 is stretched between the first piston 85 and the housing 21 to define the first pressure chamber 67 above the diaphragm 86. An atmospheric pressure chamber 52 communicating with the atmosphere is formed below it together with the above-mentioned diaphragm 51. Note that the support member 57 and the first piston 85
It may be separate from or integrated with it.

The first piston 65 is slidably provided in the housing 21 with its upper end protruding outside, and a rotating shaft 89 of a servo motor 68 such as a stepping motor fixed to the housing 21 is fixed to the upper end. An eccentric cam 70 is interlocked. This servo motor 68 is rotationally controlled by the aforementioned control device 13, and the eccentric cam 70. The elastic body 5
9 is bent, thereby making it possible to control the downward biasing force of the plunger 24.

Further, the first pressure chamber B7 is communicated with the E distribution supply source 12 via a passage 71 formed in the housing 21, a conduit 72, and a first electromagnetic on-off valve 73, and the conduit 72
The electromagnetic on-off valves 73 and 74 are opened and closed by the control device 13, and are connected to the atmosphere through a second L magnetic on-off valve 74. The pressure detection unit 75 described above is connected to the pressure detection unit 75.

In the above configuration, in a non-operating state, that is, a state in which no pedal force is applied to the brake pedal l, the control device 1 is
3 detects the state by the input detection means 14, and simultaneously controls the servo motor 6 to a non-operating position;
The first electromagnetic on-off valve 73 is closed and the second electromagnetic on-off valve 74 is opened to communicate the first pressure chamber 67 with the atmosphere. In this state, as described above, the control pressure chamber 6 of the booster mechanism 2 is exposed to 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, and therefore Since no pressure difference is generated before and after the power piston 4, the power piston 4 is also held in the non-operating position by the return spring 9.

When the brake pedal l is depressed from this state and the pedal force is transmitted to the input shaft 8, the pedal force is detected by the input detection means 14, and the value of the pedal force is determined to be a predetermined reference input value F shown in FIG. When the pressure is exceeded, the control device 13 closes the second electromagnetic on-off valve 74 and opens the first electromagnetic on-off valve 73 to supply pressure fluid into the first pressure chamber 67, and at the same time, controls the servo motor according to the input value. 68 rotational position is controlled.

Then, since the responsiveness of the '1i magnetic on-off valves 73 and 74 is better than the responsiveness of the servo motor 6, the first piston θ5 is moved to the support member by the fluid pressure introduced into the first pressure chamber 67. 57, the elastic body 59 is bent, thereby displacing the plunger 24 downward, seating the second valve seat 23 and the valve body 25, cutting off the communication between the control pressure chamber 6 and the atmosphere, and continuing. The valve body 25 is moved downward against the spring 26 to remove the valve body 25 from the first valve seat 22.

As a result, pressure fluid is supplied from the supply source 12 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 V4 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 first pressure chamber 67 is measured by the pressure detector 7.
5, and when the pressure reaches a predetermined value lower than the pressure corresponding to the input, the control device 13 closes the first electromagnetic on-off valve 73.

When the pressure inside the first pressure chamber 67 decreases, the control device 6
7 opens the first ``rL magnetic on-off valve 73 again and the second''
e. The magnetic on-off valve 74 is closed to supply pressure fluid to the first pressure chamber 67, and as a result, as shown by curve A in FIG. The first pressure is lower than the pressure B corresponding to the applied input by a predetermined value and pulsates as the electromagnetic on-off valves 73 and 74 open and close.
Control pressure is now introduced.

On the other hand, the servo motor 68 tries to displace the first piston 65 downward via the eccentric cam 70, but at the beginning of its operation, the first piston 65 is moved downward by the electromagnetic on-off valves 73 and 74. is faster, so the first piston 65 cannot be displaced downward (see the dotted line in curve C in FIG. 2). However, the servo motor 6
The amount of downward displacement of the first piston 65 by the electromagnetic valves 73 and 74 corresponds to the input value, and the amount of downward displacement of the first piston 65 by the electromagnetic on-off valves 73 and 74 is based on a pressure that is smaller than the input by a predetermined value. As a result, the servo motor will eventually begin to displace the first piston 65 downward at point D in FIG.

The amount of downward displacement of the first piston 65 by the servo motor 68 and therefore the plunger 24 by the elastic body 59
The downward biasing force of will be constant if the input value is constant. On the other hand, the control pressure in the control pressure chamber 6 is introduced into the second pressure chamber 53 from the control passage 34 through a passage 55 formed in the housing 21, and the fluid pressure introduced into the second pressure chamber 53 is The plunger 24 is urged upward through the second piston 50 against the urging force of the elastic body 59, and when the plunger 24 is moved upward, the valve body 2
5 is seated on the first valve seat 22.

Therefore, as a result, the control pressure in the control passage 34, the second pressure chamber 53, and the control pressure chamber 6 is affected by the biasing force of the elastic body 59 corresponding to the amount of descent of the first piston 65 and the support member 57 by the servo motor 68, that is, is stably controlled to the second control pressure according to the input applied to the input shaft 8 (the second
(See the solid line in the curve &laC in the figure), as a result, the power piston 4 and the output shaft 10 integrated therewith are advanced with an output corresponding to the input, and brake fluid pressure is increased in a master cylinder (not shown) linked to the output shaft 10. This occurs and a braking action is performed.

In this way, when the input value exceeds the reference input value F, first the first control pressure is obtained and the booster mechanism 2 immediately generates an output, and then the output is maintained at a stable level higher than the first control pressure. Since the second control pressure can be obtained and the booster mechanism 2 can generate a stable output based on the input value, it is possible to obtain a stable output with excellent responsiveness.

On the other hand, when the input value detected by the input detection means 14 is less than the reference input value F, the control device 13 controls the first electromagnetic on-off valve 73 and the second electromagnetic on-off valve 74
to the non-operating state, that is, the first solenoid on-off valve 73 is closed, and the second solenoid on-off valve 73 is closed. 4 is opened to place the first pressure chamber 67 in communication with the atmosphere, and the rotational position of the servo motor B8 is controlled according to the detected input value.

As a result, only the second control pressure controlled by the servo motor 68 is introduced into the control pressure chamber 6 of the booster mechanism 2, as shown by curve E in FIG. The force mechanism 2 provides a stable and relatively small output. If such a small output is required, it is no different from the request for a gentle output as described above, so the output is sent to the booster mechanism 2 by the servo motor B8, which has relatively poor response. Even if this occurs, the operator will not feel uncomfortable due to poor responsiveness.

In the above embodiment, it is determined whether or not the boosting mechanism is required to rapidly increase the output based on the magnitude of the detected input value, but the invention is not limited to this, and for example, Calculating the control pressure to be supplied into the control pressure chamber 6 of the booster mechanism 2 from the detected input value, and
The pressure detection means detects the current pressure in the control pressure chamber 6 of the booster mechanism 2, and the booster mechanism is required to rapidly increase its output based on the magnitude of the difference between the calculated control pressure and the current pressure. Alternatively, the determination can be made in various ways, such as by determining whether the input value is present or not, or by determining the magnitude of the change in the detected input value per unit time.

Further, in the above embodiment, the rotation of the servo motor 88 is transmitted to the first piston 85 using the eccentric cam 70, but the invention is not limited to this.
A pinion may be fixed to the rotating shaft 83 of the piston 8, and this pinion may be meshed with a rack formed on the first piston 65.

Further, it goes without saying that a stepping motor may be used in place of the servo motor 68 of the above embodiment, and various conditions such as the loading state of the vehicle and deceleration are inputted to the control device 13 for comprehensive control. Of course, the pressure may also be determined.

[Effects of the Invention] As described above, according to the present invention, it is possible to obtain an output of the boosting mechanism that is excellent in responsiveness and stable without causing discomfort to the operator.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the present invention, and is a system diagram showing a cross-sectional view of essential parts, and FIG. 2 is a characteristic curve diagram according to the present invention. l...Brake pedal 2...Boosting mechanism 3...Shell 4...Power piston 6...Control pressure chamber 8...Input shaft 11...Pressure control device
12... Supply source 13... Control device 14...
- Input detection means 18... Valve mechanism 21 - Housing 22... First valve seat 23... Second valve seat 24... Plunger 25... Valve body 30...
First seating part 31... Second seating part 34... Control passage 37... Supply passage 40... Discharge passage
5o...Second piston 53...Second pressure chamber
57... Support member 59... Elastic body 6
5... First piston 67... First pressure chamber 68
... Servo motor 73 ... First electromagnetic on-off valve 74.
...Second electromagnetic on-off valve patent applicant Jidosha Kiki Co., Ltd. Figure 1 Figure 2 Time

Claims (4)

[Claims] (1) A pressure control method 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 the booster to generate an output, the input being detected. The value is used as an element to determine whether or not a rapid increase in output is required from the booster mechanism, and if a rapid increase in output is required, control is performed based on the input value by controlling the opening and closing of the solenoid valve. At the same time, the servo motor opens the valve mechanism to the supply passage side with a required biasing force based on the input value to introduce the pressure fluid, and at the same time, the first control pressure lower than the pressure is immediately generated. The valve mechanism is opened toward the discharge passage by pressure against the biasing force, and the introduced pressure fluid is discharged to generate a second control pressure based on the input value following the first control pressure. , and the higher control pressure of the first control pressure and the second control pressure is supplied to the control pressure chamber of the booster mechanism, and on the other hand, when a rapid increase in output is not required, the first control pressure is supplied to the control pressure chamber of the booster mechanism. A pressure control method for a booster, characterized in that the second control pressure is supplied to the control pressure chamber of the booster without supplying the second control pressure to the control pressure chamber of the booster. (2) Pressure control of the booster according to claim 1, characterized in that it is determined from the magnitude of the detected input value whether or not the booster mechanism is required to rapidly increase its output. Method. (3) It is characterized by determining whether or not the booster mechanism is required to rapidly increase its output based on the magnitude of the difference between the control pressure corresponding to the detected input value and the current pressure in the control pressure chamber. A pressure control method for a booster according to claim 1. (4) The multiplier according to claim 1, characterized in that it is determined whether or not the booster mechanism is required to rapidly increase its output based on the magnitude of change in the detected input value per unit time. Pressure control method for force equipment.