JPH0344020B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a brake booster that boosts the pedal force applied to a brake pedal so that a large braking force can be obtained with a light pedal force.

In recent years, as a brake booster, a control device is installed outside the booster mechanism to control the supply and discharge of pressure fluid to the booster, and this control device controls the input value applied to the input shaft and the output output to the output shaft. A system has been proposed in which the supply and discharge of pressure fluid is controlled so that the output value corresponds to the input value by detecting the input value. According to the brake booster having such a configuration, the input/output characteristics can be freely changed simply by changing the correspondence between the input value and the output value in the control device, so that the input/output characteristics required for each vehicle type can be changed. It has the advantage of being able to easily deal with it even if it is hot.

By the way, the above-mentioned control device controls the output of the above-mentioned booster mechanism according to the detection signal from the input detection means that detects the above-mentioned input value, but in order to obtain a smooth and good output, it is necessary to increase the number of samplings. It is desirable to increase the resolution of the input signal and increase the processing speed. However, since increasing the number of samplings generally reduces processing speed, there is a certain limit to increasing the number of samplings, and accordingly there is also a certain limit to obtaining a smooth output.

More specifically, when input is detected from the stroke of the brake pedal, for example, the relationship between the stroke of the brake pedal and the output is such that in the low output range, the increase in output is small for a large increase in stroke. In the high output range, the output greatly increases with a small increase in stroke, so it is desirable to set the sampling number based on the high output range where the output increases greatly.

However, such a setting sets the sampling number for a small displacement of the stroke, which results in a large number of samplings per unit input, and therefore when the stroke increases greatly in the low output range. The processing of the control device becomes unable to follow. From such a thing,
The number of samplings must be reduced in consideration of the processing speed of the control device, and as a result, the number of samplings in the high output range becomes insufficient and smooth output control cannot be performed.

On the other hand, when the input is detected from the brake pedal depression force, the relationship between the brake pedal depression force and the output is opposite to the above stroke case, and in the low output range, the relationship between the brake pedal depression force and the output is In the high output range, the output increases small compared to a large increase in pedal force, so it is desirable to set the sampling number based on the low output range where the output increases greatly. However, in this case as well, the number of samplings is set for a small displacement of pedal force, so the number of samplings per unit input becomes large.
Problems similar to those described above will arise.

In view of the above-mentioned circumstances, the present invention provides an input detection device for a brake booster that is capable of selectively detecting input from the stroke of the brake pedal in the low output range and from the depression force of the brake pedal in the high output range. This is what we provide. According to such a configuration, the output changes small in response to a large change in the input in each of the low output range and the high output range, so it is possible to improve the resolution even if the number of samplings is relatively small. Therefore, smooth output control can be performed by a control device having a relatively fast processing speed with a small number of samplings.

The present invention will be described below with reference to the illustrated embodiments.
In FIG. 1, 1 is a brake pedal (not shown) pivotally supported on the vehicle body, 2 is a boosting mechanism that boosts the pedal force applied to the brake pedal 1, and this boosting mechanism 2 includes a shell 3 as a sealed container; A power piston 4 provided within this shell 3 so as to be able to move forward and backward,
The power piston 4 is provided with a diaphragm 7 that partitions the inside of the shell 3 into a pair of pressure chambers 5 and 6.

The cylindrical shaft portion 4a of the power piston 4 slidably passes through the shell 3 while maintaining airtightness, and is interlocked with the brake pedal 1 via an input shaft 8 whose tip is 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 11 attached to the front part of the shell 3. The brake fluid pressure generated in this master cylinder 11 is supplied via a conduit 12 to a wheel cylinder 14 of a wheel 13 to perform a braking action.

In this embodiment, the front pressure chamber 5 is the negative pressure introduction pipe 1.
5 to a negative pressure source such as an intake manifold (not shown), and the front pressure chamber 5 and the rear pressure chamber 6 are connected to a valve mechanism 16 composed of a solenoid valve.
They can communicate with each other via. The flow path of this valve mechanism 16 is switched by a control device 17 having a microcomputer, and when it is not in operation, the pair of pressure chambers 5 and 6 communicate with each other, and when it is in operation, communication between both chambers 5 and 6 is cut off. At the same time, the rear pressure chamber 6 can be communicated with the atmosphere.

The input shaft 8 is provided with a stroke detector 21 for detecting the stroke of the brake pedal 1 and a load detector 22 for detecting the depression force of the brake pedal 1 as an input detection means 20.
The input values detected by the input detection means 20 are inputted to the control device 17. Further, the shell 3 is provided with a pair of pressure detectors 24 and 25 constituting an output detection means 23 that indirectly detects the output of the booster mechanism 2. The pressure inside the rear pressure chamber 6 can be detected by the other pressure detector 25. and each pressure detector 2
Detection signals 4 and 25 are input to the control device 17.

The control device 17 includes the stroke detector 2
1 and the load detector 22, but if the output calculated from the detection signal received from the output detection means 23 is less than a predetermined value, that is, in the low output range, the control The device 17 inputs the detection signal from the stroke detector 21 and self-controls so as to input the detection signal from the load detector 22 in a high output range where the output exceeds a predetermined value. Then, the control device 17 calculates the output from the magnitude of the input detection signal and the input/output characteristics stored in advance in the storage circuit, and also receives the detection signal from the output detection means 23 and converts the detected value into the calculated value. The valve mechanism 16 is controlled in accordance with the output.

The input/output characteristics to be stored in the memory circuit include the range below the predetermined value of the output as the input/output characteristic of the relationship between the output and the stroke, and the range exceeding the predetermined value as the input/output characteristic of the relationship between the output and the pedal force. becomes. The input/output characteristics may be stored in the form of an output function using input values as variables, or as a table of input values and corresponding output values. Further, as the output value, the pressure difference may be used as it is, or the force applied to the output shaft 10 may be calculated from the pressure difference and the calculated value may be used as the output value.

According to the above configuration, in a non-operating state, that is, a state in which no pedal force is applied to the brake pedal 1, the control device 17 detects this state by the input detection means 20, and controls the valve mechanism 16. to cut off communication between the pressure chamber 6 and the atmosphere, and
Pressure chambers 5 and 6 are communicated with each other to introduce negative pressure into both chambers. In this state, since there is no fluid pressure difference between the front and rear sides of the power piston 4, the power piston 4 is held in the non-operating position shown in the figure by the return spring 9.

When the brake pedal 1 is depressed from this state and the pedal force is transmitted to the input shaft 8, the brake pedal 1
The stroke and pedal force of the valve mechanism 16 are detected by the stroke detector 21 and the load detector 22, but as described above, in the low output range, the control device 17 inputs the detection signal from the stroke detector 21, The fluid circuit is switched to cut off communication between the pressure chambers 5 and 6 and introduce atmospheric pressure into the pressure chamber 6. As a result, when a fluid pressure difference is generated before and after the power piston 4, the power piston 4 is moved forward against the elastic force of the return spring 9.

The fluid pressure difference generated before and after the power piston 4 is detected by the pressure detector 2 constituting the output detecting means 23.
4 and 25, and the control device 17 calculates the output based on the difference between the detected values from both pressure detectors 24 and 25. At the same time, the control device 17
The output detection means 23 calculates an output corresponding to the input from the magnitude of the input detected by the input detection means 20 and predetermined input/output characteristics.
The valve mechanism 16 is controlled so that the detected output matches the calculated output.

FIG. 2 shows an example of a general brake characteristic curve diagram, in which the output is not the differential pressure between the pressure chambers 5 and 6 but the deceleration of the vehicle. However, in a fundamental sense, the two can be considered the same. As shown in the figure, for example, in the low output range A where the deceleration of the vehicle is 0.6G or less, the relationship between the amount of change in stroke and the amount of change in output, and the amount of change in pedal force and the amount of change in output. If we compare the relationship between has changed significantly.

In this embodiment, in the low output range A, the control device 17 inputs the detection signal from the stroke detector 21, and in this range, even if the stroke changes greatly, the change in output is small, so it is relatively Even with a small number of samples, the resolution becomes high. Furthermore, in the high output range B, the control device 17
inputs the detection signal from the load detector 22, and in this region the change in output is small even if the pedal force changes greatly, so the resolution is high even with a relatively small number of samplings, and therefore the input Even if the signal is sampled with a relatively small number of samples, it is possible to always maintain an appropriate number of samples over the entire range of output fluctuations, which allows smooth processing over the entire range of output fluctuations at high processing speeds. This makes it possible to perform precise output control.

In this way, when the output shaft 10 integrated with the power piston 4 is advanced with an output corresponding to the input, brake fluid pressure is generated in the master cylinder 11 linked to the output shaft 10, and that fluid pressure is transferred to the conduit. 12 to the wheel cylinder 14 of the wheel 13, so that a braking action takes place.

Furthermore, when the brake action is released, the pedal force applied to the input shaft 8 decreases, and accordingly, the fluid pressure difference before and after the power piston 4 is controlled to gradually decrease, and finally the above-mentioned non-operating state is reached. The brake action is released.

Note that it is desirable to switch the inputs from the stroke detector 21 and the load detector 22 based on the magnitude of the output as in the above embodiment. The switching may be performed based on the reference value. Further, in the above embodiment, the control device 17 itself determines whether to switch the input, but a dedicated switch may be provided and a signal selected by the switch may be input to the control device 17. In either case, care must be taken to ensure smooth continuity of output control during switching.

Further, the output detecting means is not limited to that of the embodiment described above, and other various configurations can be used. For example, the brake fluid pressure generated in the master cylinder can be detected, or the magnitude of the output directly applied to the output shaft can be detected using a load cell or the like.

As described above, in the present invention, the input detection means includes a stroke detector that detects the depression stroke of the brake pedal, and a load detector that detects the depression force of the brake pedal, and the control device has an output or an input. The detection signal from the stroke detector is input when the stroke is less than a predetermined value, and the detection signal from the load detector is input when the stroke exceeds the predetermined value. Even if sampling is performed with a relatively small sampling number, it is possible to always maintain an appropriate sampling number over the entire range of output fluctuations, which allows smooth output control over the entire output range at high processing speed. You can get the effect of being able to do it.

[Brief explanation of drawings]

Figure 1 is a system diagram showing one embodiment of the present invention, Figure 2 is a system diagram showing an embodiment of the present invention.
The figure is a brake characteristic curve diagram. 1...Brake pedal, 2...Boosting mechanism, 5,
6...Pressure chamber, 8...Input shaft, 10...Output shaft,
11...Master cylinder, 16...Valve mechanism, 1
7...control device, 20...input detection means, 21...
...Stroke detector, 22...Load detector, 23
...Output detection means.

Claims (1)

[Claims] 1. An input detection means for detecting the magnitude of the input applied to the brake pedal, and a booster mechanism that has a pressure chamber into which pressure fluid is introduced and generates an output according to the fluid pressure introduced into the pressure chamber. , an output detection means that directly or indirectly detects the output of the booster mechanism, a valve mechanism that switches a fluid circuit communicating with the pressure chamber to control supply and discharge of pressure fluid to the pressure chamber, and the input detection means. Receiving a detection signal from the means, calculates an output based on the magnitude of the input and predetermined input/output characteristics, and receiving a detection signal from the output detection means so that the detected value corresponds to the calculated output. and a control device for controlling the valve mechanism, wherein the input detection means is a stroke detector that detects the depression stroke of the brake pedal, and a load detector that detects the depression force of the brake pedal. The control device inputs a detection signal from the stroke detector when the output or input is below a predetermined value, and receives a detection signal from the load detector when the output or input exceeds the predetermined value. An input detection device for a brake booster, characterized in that an input is input.