JPH0426246Y2 - - Google Patents

Description

[Detailed description of the invention] Purpose of the invention [Industrial application field] The invention provides a polarity signal representing the direction of the relative speed between the wheels and the vehicle body, and a polarity signal representing the direction of the relative speed between the vehicle body and the road surface. The present invention relates to a damping force control device for a shock absorber for a vehicle, which determines both polarity signals and switches the damping force of the shock absorber depending on whether bipolar signals are in phase or in opposite phase.

[Prior Art] Conventionally, a technique for suppressing vertical vibration of a vehicle is known based on the so-called Skyhook principle.
That is, the distance from a reference line imaginary in the air to the vehicle body and the distance from the reference line to the wheels are controlled to suppress vertical vibration in the vehicle. When applying this technology to an actual vehicle, bipolar signals indicating the direction of the relative speed between the car body and the road surface and the direction of the relative speed between the wheels and the car body are determined, and whether the bipolar signals are in phase or out of phase. The damping force of the vehicle's shock absorber is controlled to be switched to a high state or a low state depending on the situation.

Incidentally, a polarity signal indicating the direction of the relative speed between the wheel and the vehicle body has been generated by measuring the displacement between the wheel and the vehicle body and differentiating the displacement. Differentiation of this displacement has been performed, for example, by processing an electrically measured displacement signal with a differentiation circuit such as a high-pass filter.

In addition, the polarity signal indicating the direction of the relative speed between the vehicle body and the road surface is obtained by detecting the vertical acceleration of the vehicle body using an acceleration sensor, and integrating the detected signal using an integrating circuit such as a low-pass filter. I wanted to generate it by doing this.

[Problems to be solved by the invention] However, when the polarity signals indicating the directions of the relative velocities of the wheels and the vehicle body and the vehicle body and the road surface are obtained using a differential circuit and an integral circuit as in the conventional method, the respective It was said that due to the frequency of the input signal, the phase difference of each polarity signal deviated significantly from the calculated values of differential (+90°) and integral (-90°), making it impossible to properly switch the damping force of the shock absorber. There was a problem.

That is, for example, when the frequency of the displacement signal is equal to the cut-off frequency of the high-pass filter that constitutes the differentiating circuit, the phase of the polar signal leads the phase of the displacement signal by 90 degrees, but the frequency of the displacement signal is equal to the cut-off frequency of the high-pass filter that constitutes the differentiating circuit. Moving away from the frequency, the phase difference between the displacement signal and the polarity signal further decreases or increases. Conversely, for example, when the frequency of the acceleration signal from the acceleration sensor that detects the vertical acceleration of the vehicle body (the vibration frequency of the vehicle body) is equal to the cutoff frequency of the low-pass filter that constitutes the integrating circuit, the phase of the acceleration signal Therefore, the phase of the polar signal is delayed by 90°, but as the frequency of the acceleration signal moves away from the cutoff frequency of the integrating circuit, the phase difference between the acceleration signal and the polar signal further decreases or increases. In general, the displacement between the wheels and the vehicle body and the vertical acceleration of the vehicle body change irregularly depending on road surface conditions, so the frequencies of the displacement signal and the acceleration signal always vary greatly.

For this reason, in the conventional device that uses the differential circuit and the integral circuit as described above to determine the relative speed between the wheels and the vehicle body and the relative speed between the vehicle body and the road surface, and generates the sign as a polarity signal of each relative speed, A phase difference that cannot be accurately grasped will always occur between the polarity signals, and even if shock absorber damping force switching control is performed based on these polarity signals, vehicle body vibration cannot be effectively suppressed. be.

The present invention was developed in view of these problems, and even if the frequency of the displacement signal or acceleration signal changes, there is no phase difference between each polarity signal, and damping force switching control of the shock absorber is always performed well. It is an object of the present invention to provide a damping force control device for a shock absorber for a vehicle.

Structure of the invention [Means for solving the problem] That is, the present invention, which was made to achieve the above object, detects the displacement between the wheels and the vehicle body, and moves them to a predetermined position in an order according to the direction of the displacement. First and second having a phase difference
displacement detection means for outputting a displacement signal; when the phase of the first displacement signal outputted by the displacement detection means is ahead of the phase of the second displacement signal, the first phase signal is outputted; phase discriminating means for outputting a second phase signal when the phase of the displacement signal is ahead of the phase of the first displacement signal; and either the first or second phase signal output by the phase discriminating means. a sequential means for outputting an inverted sequential signal by using one as a memory input signal and the other as a memory release signal, and outputting the sequential signal as a first polarity signal representing the direction of the relative speed between the wheels and the vehicle body. a first polarity signal generation means for detecting acceleration in the vertical direction of the vehicle body; a sample hold circuit for sample-holding the acceleration signal output from the acceleration detection means using a predetermined clock signal; a comparator that compares the sample hold value by the circuit with the acceleration signal from the acceleration detection means and outputs a comparison signal that is inverted according to the comparison result; a second polarity signal generation means for outputting a second polarity signal representing the direction; and attenuation of the shock absorber depending on whether each polarity signal outputted from each of the polarity signal generation means is in phase or in opposite phase. The gist of the present invention is a damping force control device for a vehicle shock absorber, comprising: a damping force switching means for switching the force;

[Function] In the damping force control device for a vehicle shock absorber of the present invention configured as described above, the first
The polarity signal generating means outputs a first polarity signal representing the direction of the relative speed between the wheels and the vehicle body, and
The second polarity signal generation means outputs a second polarity signal representing the direction of relative speed between the vehicle body and the road surface, and the damping force switching means outputs a second polarity signal representing the direction of the relative speed between the vehicle body and the road surface, and the damping force switching means determines whether each polarity signal output from each of these polarity signal generation means is The damping force of the shock absorber is switched depending on whether they are in phase or out of phase.

Further, in the first polarity signal generating means, the displacement detecting means detects the displacement between the wheel and the vehicle body, and detects the first and second polarity signals having a predetermined phase difference in order according to the direction of the detected displacement. outputs a displacement signal of
The phase determining means outputs the first phase signal when the phase of the first displacement signal is ahead of the phase of the second displacement signal, and when the phase of the second displacement signal is ahead of the phase of the first displacement signal, the phase determining means outputs the first phase signal. When the phase is leading, the phase determining means outputs a second phase signal. Then, the sequence means outputs an inverted sequence signal using either the first or second phase signal as a storage input signal and the other as a storage release signal, and uses this sequence signal as a signal for the relative speed between the wheels and the vehicle body. It is output to the damping force switching means as a first polarity signal representing the direction.

Next, in the second polarity signal generating means,
The acceleration detection means detects the vertical acceleration of the vehicle body, and the sample and hold circuit samples and holds the detection signal using a predetermined clock signal. Then, the comparator compares the sampled and held signal with the acceleration signal from the acceleration detection means, outputs a comparison signal that is inverted according to the comparison result, and uses this comparison signal to determine the relative relationship between the vehicle body and the road surface. It is output to the damping force switching means as a second polarity signal representing the direction of velocity.

That is, in the present invention, the first polarity signal generating means generates the first polarity signal representing the direction of the relative speed between the wheels and the vehicle body without using a differentiation circuit, and the second polarity signal generating means generates the first polarity signal representing the direction of the relative speed between the wheels and the vehicle body. Accordingly, a second polarity signal representing the direction of the relative speed between the vehicle body and the road surface is generated without using an integrating circuit.

Therefore, the first polarity signal that does not cause a phase difference with the relative displacement even if the frequency of the relative displacement between the wheels and the vehicle body due to vehicle vibration changes is input to the damping force switching means. A second polarity signal is input that does not cause a phase difference with the vehicle acceleration even if the vibration frequency of the vehicle body changes, and the damping force of the shock absorber can be well controlled based on these polarity signals. It becomes like this.

[Example] Next, an example of the present invention will be described based on the drawings.

First, FIG. 2 is a system configuration diagram showing the overall configuration of a shock absorber control device to which the present invention is applied.

A shock absorber control device 1 rotates a shock absorber 5 installed in parallel with a coil spring 4 interposed between a wheel 2 and a vehicle body 3, a control rod 5a of the shock absorber 5, and a valve 5b to damp the shock absorber. A motor 6 that switches the force between hard (high damping force) and soft (low damping force), a rotary encoder 7 that detects the relative displacement between the wheels 2 and the vehicle body 3, and an acceleration sensor that detects the vertical acceleration of the vehicle body 3. 8. A wheel-to-vehicle relative speed polarity signal generation circuit 9 that generates a wheel-to-vehicle relative speed polarity signal from the displacement signal output from the rotary encoder 7; a vehicle-to-road relative speed polarity signal from the acceleration signal output from the acceleration sensor 8; A vehicle body-to-road surface relative speed polarity signal generating circuit 10 generates a vehicle body-to-road surface relative speed polarity signal generating circuit 10, which inputs the wheel-to-vehicle body relative speed polarity signal and vehicle body-to-road surface relative speed polarity signal and outputs a damping force switching signal that switches the damping force of the shock absorber 5. a force switching signal generation circuit 11; a drive circuit 1 that drives the motor 6 in accordance with the damping force switching signal;
It is composed of 2.

In this embodiment, the rotary encoder 7 and the wheel-to-vehicle relative speed polarity signal generation circuit 9 correspond to the first polarity signal generation means, and the acceleration sensor 8 and the vehicle-body relative speed polarity signal generation circuit 10 correspond to the first polarity signal generation means.
corresponds to the second polarity signal generating means, and the motor 6,
The damping force switching signal generation circuit 11 and the drive circuit 12 correspond to damping force switching means.

Here, wheel-to-vehicle relative speed polarity signal generation circuit 9
is composed of a phase discriminator 13 as a phase discriminator and an RS flip-flop 14 as a sequential means. Further, the vehicle body-to-road surface relative speed polarity signal generation circuit 10 includes a strain amplifier 15, a sample hold circuit 16, a comparator 17, and an oscillator 18. Furthermore, the damping force switching signal generating circuit 11 is composed of an anticoincidence circuit 19, a NOT circuit 20, RS flip-flops 21 and 22, and Schmitt trigger circuits 23 and 24.

Next, wheel-to-vehicle relative speed polarity signal generation circuit 9
The configuration will be explained based on FIG.

As shown in FIG. 1, the wheel-to-vehicle relative speed polarity signal generation circuit 9 includes capacitors 31, 32,
Phase discriminator 13 consisting of NOT circuits 33, 34, NAND circuits 35, 36, NAND circuits 37, 38
It consists of an RS flip-flop 14 and a NOT circuit 39.

Next, its operation will be explained with reference to the circuit diagram of FIG. 1 and the timing charts of FIGS. 3 and 4. Note that the waveforms at each point shown in FIGS. 3 and 3 are observed at the positions indicated by the same reference numerals in the circuit diagram of FIG. 1. When the relative displacement between the wheels and the vehicle body decreases, the rotary encoder 7 as a displacement detecting means detects a phase difference of 1/4 wavelength (time T1 and time T2
Two pulse trains are output with an interval of . The waveform at point a changes to a roll level at time T3, and at this time, due to the action of the capacitor 31, a pulse train similar to the waveform at point c is obtained. The waveform at point c is inverted like the waveform at point d by the action of the NOT circuit 33. The d-point waveform and the b-point waveform are
is input to the NAND circuit 35, and as its output e
A pulse train having a point waveform is obtained as one output of the phase discriminator 13. As shown in FIG. 4, when the relative displacement between the wheels and the vehicle body decreases, the waveform at point e, which is one output of the phase discriminator 13, becomes a pulse train, and the waveform at point f, which is the other output of the phase discriminator 13, becomes a pulse train. maintained at a high level. On the other hand, when the relative displacement between the wheels and the vehicle body increases, the waveform at point e is maintained at a high level, and the waveform at point f becomes a pulse train. above e
Point waveform and f point waveform are RS flip-flop 1
The signal is input to NAND circuits 37 and 38 that constitute 4. Therefore, in response to the change of the e-point waveform to low level at time T11, the g-point waveform, which is the output of the RS flip-flop 14, is set to high level. On the other hand, in response to the change of the f-point waveform to low level at time T12, the g-point waveform is reset to low level. Similarly, the waveform at point g is
Time T1 according to changes in the e-point waveform and f-point waveform.
3. At time T14 and time T15, set...
Repeat the reset. The waveform at point g, which is the output of the RS flip-flop 14, is inverted by the action of the NOT circuit 39, and is output as the waveform at point h, which is a wheel-to-vehicle relative speed polarity signal.

Next, the vehicle body-to-road surface relative speed polarity signal generation circuit 1
The configuration of 0 will be explained based on FIG.

The vehicle body-to-road surface relative speed polarity signal generation circuit 10 includes:
As shown in FIG. 5, a strain amplifier 15, a resistor 41, a sample hold circuit 16, a resistor 4
2, 43, a comparator 17, and an oscillator 18.

Next, its operation will be explained with reference to the circuit diagram of FIG. 5 and the timing chart of FIG. 6. In addition,
The waveforms at each point shown in FIG. 6 are observed at the positions indicated by the same reference numerals in the circuit diagram of FIG. The detection result of the acceleration in the vertical direction of the vehicle body by the acceleration sensor 8 is inputted to the strain amplifier 15.
It is output as an i-point waveform which is a vertical acceleration signal. On the other hand, a clock signal having a j-point waveform is input from the oscillator 18 to the sample hold circuit 16. The sample and hold circuit 16 samples and holds the i-point waveform, which is a vertical acceleration signal, according to the clock signal indicated by the j-point waveform.
Outputs a k-point waveform which is a sampled and held signal. The comparator 17 inputs the i-point waveform and the k-point waveform, and outputs the m-point waveform which becomes high level when the voltage of the k-point waveform exceeds the voltage of the i-point waveform. In other words, time T2 when the vehicle body vertical acceleration increases
1 to time T22, the voltage of the i-point waveform is higher than the voltage of the k-point waveform, so the m-point waveform is at a low level. However, between time T22 and time T23 when the vertical acceleration of the vehicle body decreases, the voltage of the k-point waveform exceeds the voltage of the i-point waveform, so the m-point waveform is at a high level. Thereafter, similarly, the m-point waveform is at time T2.
Low level from 3 to time T24, time T24
It changes to a high level from to time T25. In this way, the vehicle body-to-road surface relative speed polarity signal m
A point waveform is output from the comparator 17.

Next, the previously described shock absorber control device 1
The operation will be explained according to the timing chart of FIG. The operation shown in FIG. 7 is as shown in FIG.
and in the direction indicated by B, frequency 1.5 [Hz] amplitude ±10
This is when [mm] of vibration is applied.

As shown in FIG. 7, when the vibration of the wheel 2 is started, the wheel-to-vehicle relative speed polarity signal (waveform at point h in FIG. 2) is output from the wheel-to-vehicle relative speed polarity signal generation circuit 9. A vehicle body-to-road relative speed polarity signal (second
The m-point waveform in the figure) is the damping force switching signal generation circuit 1.
1 is input. The damping force switching signal generation circuit 11
outputs a hard switching signal (waveform at point p in FIG. 2) and a soft switching signal (waveform at point g in FIG. 2) to the drive circuit 12 in response to both of the above input signals, and the drive circuit 12 outputs a hard switching signal (waveform at point p in FIG. 2) and a soft switching signal (waveform at point g in FIG. 2). In response to the soft switching signal, the motor 6 is rotated in the normal direction, and in response to the soft switching signal, the motor 6 is rotated in the reverse direction to switch the damping force of the shock absorber 5 into two stages. That is, at time T31, both the wheel-to-vehicle relative speed polarity signal and the vehicle-body to road surface relative speed polarity signal are at high level and in phase, so that at time T32, which is a predetermined time after time T31,
The hardware switching signal is output (ON) until On the other hand, at time T33, the wheel-to-vehicle relative speed polarity signal is at a high level, but the vehicle-body to road relative speed polarity signal changes to a roll level, and the two polarity signals are in reverse phase, so that a predetermined period of time elapses from time T33. The software switching signal is output (ON) until the later time T34.
be done. Thereafter, control is repeated for outputting a hard switching signal when the bipolar signals are in phase, and a soft switching signal when they are in opposite phase, respectively, for a predetermined period of time.

In this embodiment, the rotary encoder 7 functions as a displacement detecting means, the phase discriminator 13 functions as a phase determining means, and the RS flip-flop 14 functions as a sequential means.

According to this embodiment having the above configuration, the simple configuration consisting of the rotary encoder 7, phase discriminator 13, and RS flip-flop 14 prevents displacement between the vehicle body and the wheels even when vibrations of various frequencies are applied to the wheels. It is possible to obtain a wheel-to-vehicle relative speed polarity signal that does not cause a phase difference.

Additionally, a wheel-to-vehicle relative speed polarity signal generation circuit 9
phase discriminator 13 and RS flip-flop 1
4, there is no need to adjust the circuit elements, reducing manufacturing man-hours and manufacturing costs, and improving the reliability of the wheel-to-vehicle relative speed polarity signal generating circuit 9.

Furthermore, with a simple configuration consisting of an acceleration sensor 8, a sample hold circuit 16, and a comparator 17, the vehicle body-to-road surface relative speed polarity signal does not cause a phase difference with respect to the vertical acceleration of the vehicle body even when the frequency of vehicle body vibration changes. can be obtained.

In addition, the vehicle body-to-road surface relative speed polarity signal generation circuit 1
Since normal operation is possible by simply adjusting the input resistance value of the comparator 17 among 0, the number of adjustment steps and manufacturing costs can be reduced, and the reliability of the vehicle body-to-road surface relative speed polarity signal generation circuit 10 is also improved.

Furthermore, it is possible to obtain a wheel-to-vehicle relative speed polarity signal that does not cause a phase difference with respect to displacement between the wheels and the vehicle body, and a vehicle-body to road surface relative speed polarity signal that does not cause a phase difference with respect to vertical acceleration of the vehicle body. By using the above bipolar signals, shock absorber damping force switching control for the purpose of suppressing vehicle body vibration can be suitably performed based on the Skyhook principle. That is, it is possible to realize control in which the damping force is switched between two levels, high and low, for each cycle of vibration between the wheels and the vehicle body.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments in any way, and it goes without saying that it can be implemented in various forms without departing from the gist of the present invention. .

Effects of the Invention As described in detail above, according to the damping force control device for a vehicle shock absorber of the present invention, the first polarity signal generating means generates a frequency of the relative displacement between the wheel and the vehicle body caused by vehicle vibration. The polarity signal shown in FIG. 1 that does not cause a relative displacement and phase difference even when
A second polarity signal is generated that does not cause a phase difference with the vehicle body acceleration even if the vibration frequency of the vehicle body changes.

Therefore, as in the past, the phase difference between the first polarity signal representing the direction of the relative speed between the wheels and the vehicle body and the second polarity signal representing the direction of the relative speed between the vehicle body and the road surface is There has never been a case where the polarity is shifted due to
It becomes possible to switch the damping force of the shock absorber with high precision.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a wheel-to-vehicle relative speed polarity signal generation circuit according to an embodiment of the present invention, FIG. 2 is a system configuration diagram of a shock absorber control device, and FIGS. 3 and 4 are wheel-to-vehicle relative speed polarity signal generation circuits. Timing chart showing the operation of the speed polarity signal generation circuit, No. 5
The figure is a circuit diagram showing the vehicle body-to-road surface relative speed polarity signal generation circuit, FIG. 6 is a timing chart showing its operation, FIG. 7 is a timing chart showing the operation of the shock absorber control device, and FIG. 8 is a timing chart showing its operation. It is an explanatory view showing a shaking state. 5...Shock absorber, 6...Motor, 7
...Rotary encoder, 8...Acceleration sensor,
9...Wheel-to-vehicle relative speed polarity signal generation circuit, 1
0...Vehicle body-to-road surface relative speed polarity signal generation circuit, 1
DESCRIPTION OF SYMBOLS 1... Damping force switching signal generation circuit, 12... Drive circuit, 13... Phase discriminator, 14... RS flip-flop, 16... Sample hold circuit, 17
……comparator.

Claims (1)

[Claims for Utility Model Registration] Displacement between the wheels and the vehicle body is detected, and first and second components having a predetermined phase difference are detected in an order according to the direction of the displacement.
displacement detection means for outputting a displacement signal; when the phase of the first displacement signal outputted by the displacement detection means is ahead of the phase of the second displacement signal, the first phase signal is outputted; phase discriminating means for outputting a second phase signal when the phase of the displacement signal is ahead of the phase of the first displacement signal; and either the first or second phase signal output by the phase discriminating means. a first sequential means for outputting an inverted sequential signal, one of which is used as a memory input signal and the other as a memory release signal; A polarity signal generating means, an acceleration detecting means for detecting the vertical acceleration of the vehicle body, a sample hold circuit that samples and holds the acceleration signal outputted by the acceleration detecting means using a predetermined clock signal, and a sample hold value by the sample hold circuit. and an acceleration signal from the acceleration detecting means, and outputs a comparison signal that is inverted according to the comparison result, and converts the comparison signal into a polarity signal representing the direction of the relative speed between the vehicle body and the road surface. and a damping force switching means for switching the damping force of the shock absorber depending on whether each polarity signal outputted from each of the polarity signal generation means is in phase or in opposite phase. A damping force control device for a shock absorber for a vehicle, characterized by comprising the following.