JPH0633421Y2 - Damping force control device for vehicle shock absorber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention [Industrial field of application] The present invention is directed to a polarity signal of a wheel-to-vehicle relative speed indicating whether a wheel and a vehicle body are approaching or moving away from each other, and a vehicle body and a road surface approaching each other. Of the vehicle shock absorber, which detects the polarity signal of the relative speed of the vehicle body and the road surface, which indicates whether the vehicle is moving away or away, and switches the damping force of the shock absorber depending on whether the detected polarity signals are in phase or in reverse phase. The present invention relates to a damping force control device.

[Prior Art] Conventionally, a technology for suppressing vertical vibration of a vehicle is known based on the so-called skyhook principle. That is, the vertical vibration of the vehicle is controlled by controlling the distance from the virtual reference line to the vehicle body in the air and the distance from the reference line to the wheels. When this technology is applied to an actual vehicle, the polarity signal of the vehicle body-to-road surface relative speed, which indicates whether the vehicle body is approaching or moving away from the road surface, and whether the vehicle body is approaching or moving away from the wheels. The respective polar signals of the wheel-vehicle relative speed are obtained, and control is performed to switch the damping force of the shock absorber of the vehicle to a high value or a low value depending on whether the polar signals have the same phase or opposite phases. .

By the way, the polarity signal of the vehicle body-to-road surface relative speed is generated by measuring the vertical acceleration of the vehicle body and integrating the vertical acceleration. The integral of this vertical acceleration is
For example, the vertical acceleration signal measured electrically is processed by an integrating circuit such as a low-pass filter.

[Problems to be Solved by the Invention] However, it is said that the phase difference between the polarity signal output from the integrating circuit and the vertical acceleration signal changes significantly with the frequency fluctuation of the measured vertical acceleration signal. There was a problem. For example, when the frequency of the vertical acceleration signal is equal to the cutoff frequency of the low-pass filter forming the integrating circuit, the phase of the polarity signal is delayed by 90 ° with respect to the phase of the vertical acceleration signal. However, when the frequency of the vertical acceleration signal deviates from the cutoff frequency, the phase difference between the vertical acceleration signal and the polarity signal further decreases or increases. In general, the vertical acceleration of the vehicle body changes irregularly depending on the road surface condition, so the frequency of the vertical acceleration signal constantly fluctuates greatly. Therefore, there is always a phase difference that cannot be accurately grasped between the vertical acceleration signal and the polarity signal.

Therefore, as described above, the conventional damping force control device that switches the damping force of the shock absorber by using the polarity signal having a phase difference that cannot be specified with respect to the vertical acceleration signal cannot effectively suppress the vehicle body vibration. was there.

The present invention has been made in view of these problems, and accurately detects the polarity signal of the vehicle body-to-road surface relative speed to control the damping force switching of the shock absorber without being affected by the frequency fluctuation of the vertical acceleration signal. An object of the present invention is to provide a damping force control device for a vehicle shock absorber, which can be always executed well.

DISCLOSURE OF THE INVENTION [Means for Solving the Problems] The present invention, which has been made to achieve the above object, provides a displacement detecting means for detecting a relative displacement between a wheel and a vehicle body, and a detection signal from the displacement detecting means. Based on the first polarity signal generating means for generating a polarity signal of the wheel-to-vehicle body relative speed indicating whether the wheel and the vehicle body are approaching or moving away from each other, an acceleration for detecting the vertical acceleration of the vehicle body and outputting an acceleration signal. Detecting means, holding means for sampling and holding the acceleration signal output from the acceleration detecting means in a predetermined cycle, and comparing the acceleration signal held by the holding means with the acceleration signal output from the acceleration detecting means. Second polarity signal generating means for generating a polarity signal of the relative speed of the vehicle body and the road surface, which indicates whether the vehicle body and the road surface are approaching or moving away from each other, based on the comparison result. Damping force switching means for increasing the damping force of the shock absorber when the polarity signals output from the polarity signal generating means are in phase, and decreasing the damping force of the shock absorber when the polarity signals are in opposite phase The gist is a damping force control device for a vehicle shock absorber, which is characterized by including:

[Operation] In the damping force control device for a vehicle shock absorber according to the present invention configured as described above, the displacement detecting means detects the relative displacement between the wheel and the vehicle body, and the first polarity generating means detects the relative displacement. Based on the detection result, a wheel-to-vehicle relative velocity polarity signal indicating whether the wheel and the vehicle body are approaching or moving away from each other is generated.

Further, the acceleration detecting means detects the vertical acceleration of the vehicle body, and the holding means samples and holds the acceleration signal output from the acceleration detecting means at a predetermined cycle. Then, the second polarity signal generating means compares the acceleration signal held by the holding means with the acceleration signal output from the acceleration detecting means, and based on the comparison result, is the vehicle body and the road surface approaching each other? A polarity signal of the relative speed of the vehicle body and the road surface, which indicates whether the vehicle is moving away, is generated.

Then, the damping force switching means increases the damping force of the shock absorber if the polarity signals output from the polarity signal generating means are in phase or opposite phase if the polarity signals are in phase. Then, the damping force of the shock absorber is switched to two stages, high and low, by the procedure of lowering the damping force of the shock absorber when the polarity signals have opposite phases.

That is, according to the present invention, the holding means and the second polarity signal generating means, based on the acceleration detection signal from the acceleration detecting means, without using an integrating circuit as in the conventional case,
A polarity signal is generated that indicates the direction of the vehicle-to-road surface relative velocity, which indicates whether the vehicle body and the road surface are approaching or moving away from each other.

Therefore, the polarity signal of the vehicle body-to-road surface relative speed input to the damping force switching means does not cause a phase difference with the vehicle body acceleration even if the vertical vibration frequency of the vehicle body fluctuates. The damping force of the shock absorber can be controlled well.

The reason why the second polarity signal generating means can generate the polarity signal of the vehicle body-to-road surface relative speed based on the magnitude comparison result of the acceleration signal held by the holding means and the acceleration signal output from the acceleration detecting means is as follows. It is as follows.

First, since the vehicle body-to-road surface relative speed is a differentiation of the distance (relative displacement) between the vehicle body and the road surface, the phase advances by 90 degrees with respect to the change in the distance, and the polarity of the vehicle body-to-road surface relative speed is , "Positive" when the vehicle body and the road surface are distant from each other, and "negative" when the vehicle body and the road surface are close to each other.

On the other hand, since the vertical acceleration of the vehicle body detected by the acceleration detecting means corresponds to the relative acceleration of the vehicle body-to-road surface, the phase is advanced by 90 degrees with respect to the vehicle body-to-road surface relative velocity.

Therefore, in a region where the vehicle body and the road surface are distant from each other and the extreme velocity of the vehicle body-to-road surface relative velocity is “positive”, the vehicle body acceleration decreases, and conversely, the vehicle body and the road surface are close to each other, and The vehicle body acceleration increases in the region where the polarity of the speed becomes “negative”.

Therefore, in the present invention, the second polarity signal generating means compares the magnitude of the acceleration signal held by the holding means with the acceleration signal output from the acceleration detecting means,
Since the increasing / decreasing direction of the vertical acceleration of the vehicle body is detected, and based on the detection result (comparison result), a polarity signal of the vehicle body-to-road surface relative speed indicating whether the vehicle body is approaching or distant from the road surface is generated. is there.

[Embodiment] Next, an embodiment of the present invention will be described with reference to 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.

The shock absorber control device 1 rotates a control rod 5a and a valve 5b of a shock absorber 5, a shock absorber 5 installed in parallel with a coil spring 4 interposed between a wheel 2 and a vehicle body 3, and a damping force. To switch between hard (high damping force) and soft (low damping force) in two stages, a rotary encoder 7 that detects relative displacement between the wheel 2 and the vehicle body 3, and an acceleration sensor 8 that detects vertical acceleration of the vehicle body 3. , A wheel-to-vehicle relative velocity polarity signal generation circuit 9 for generating a wheel-to-vehicle relative velocity polarity signal from a displacement signal output from the rotary encoder 7, and a vehicle-to-road surface relative velocity polarity signal from an acceleration signal output from the acceleration sensor 8. A vehicle-to-road surface relative velocity polarity signal generation circuit 10 for generating the wheel-to-vehicle relative velocity polarity signal and the vehicle-to-road surface relative velocity polarity signal Input to the shock absorber 5
It comprises a damping force switching signal generating circuit 11 for outputting a damping force switching signal for switching the damping force, and a drive circuit 12 for driving the motor 6 according to the damping force switching signal.

In the present embodiment, the rotary encoder 7 serves as the displacement detecting means and the wheel-to-vehicle relative velocity polarity signal generating circuit 9 is used.
Is the first polarity signal generating means, the acceleration sensor 8 is the acceleration detecting means, the vehicle body-to-road surface relative velocity polarity signal generating circuit 10 is the holding means and the second polarity signal generating means, and the motor 6 and the damping force switching signal are generated. The circuit 11 and the drive circuit 12 correspond to damping force switching means, respectively.

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

Next, the configuration of the vehicle body-to-road surface relative velocity polarity signal generation circuit 10 will be described with reference to FIG.

As shown in FIG. 1, the vehicle body-to-road surface relative velocity polarity signal generation circuit 10 includes a strain amplifier 15, a resistor 31, a sample hold circuit 16, resistors 32 and 33, a comparator 17, and an oscillator 18.

Next, the operation will be described with reference to the circuit diagram of FIG. 1 and the timing chart of FIG. The waveform of each point shown in FIG. 3 is observed at the positions shown by the same reference numerals in the circuit diagram of FIG. The detection result of the vertical acceleration of the vehicle body by the acceleration sensor 8 is input to the strain amplifier 15 and output as a point a waveform which is a vertical acceleration signal. On the other hand, a clock signal having a waveform of point b is input from the oscillator 18 to the sample hold circuit 16.
The sample and hold circuit 16 samples and holds the a-point waveform which is the vertical acceleration signal in accordance with the clock signal indicated by the b-point waveform, and outputs the c-point waveform which is the sampling hold signal. The comparator 17 inputs the point a waveform and the point c waveform, and outputs a d point waveform which becomes high level when the voltage of the point c waveform exceeds the voltage of the point a waveform. That is, between time T1 and time T2 when the vehicle body vertical acceleration increases,
Since the voltage of the a point waveform is higher than the voltage of the c point waveform, the d point waveform becomes low level. However, between time T2 and time T3 when the vertical acceleration of the vehicle body decreases, the voltage at the point c exceeds the voltage at the point a, so the waveform at the point d becomes high level.
Similarly, the d-point waveform changes to low level from time T3 to time T4 and to high level from time T4 to time T5. In this way, d which is the vehicle-to-road surface relative velocity polarity signal
The point waveform is output from the comparator 17.

Next, the configuration of the wheel-to-vehicle body relative velocity polarity signal generation circuit 9 will be described with reference to FIG.

As shown in FIG. 4, the wheel-to-vehicle body relative velocity polarity signal generation circuit 9 includes capacitors 41 and 42, NOT circuits 43 and 44, and a NAND circuit 4
Phase discriminator 13 consisting of 5,46 and RS consisting of NAND circuits 47 and 48
It is composed of a flip-flop 14 and a NOT circuit 49.

Next, the operation will be described with reference to the circuit diagrams of FIG. 4, and the timing charts of FIGS. 5 and 6. In addition, FIG.
The waveform of each point shown in FIG. 6 is observed at the positions shown by the same reference numerals in the circuit diagram of FIG. When the relative displacement between the wheel and the vehicle body decreases, the rotary encoder 7 outputs 1 as shown by the point e waveform and the point f waveform shown in FIG.
Two pulse trains having a phase difference of / 4 wavelength (interval between time T11 and time T12) are output. The point e waveform is at time T13.
Changes to a low level at
By the action of 41, a pulse train having a g-point waveform is obtained.
The NOT circuit 43 acts to invert the g-point waveform like the h-point waveform. The h-point waveform and the f-point waveform are input to the NAND circuit 45, and as its output, a pulse train like the i-point waveform is obtained as one output of the phase discriminator 13. As shown in FIG. 6, when the wheel-to-body relative displacement decreases, the waveform of the point i which is one output of the phase discriminator 13 becomes a pulse train, and the waveform of the point j which is the other output of the phase discriminator 13 becomes Maintained at high level. On the other hand, when the wheel-vehicle phase displacement increases, the waveform at point i is maintained at a high level and the waveform at point j becomes a pulse train. The i-point waveform and the j-point waveform are input to the NAND circuits 47 and 48 forming the RS flip-flop 14. Therefore, the k-point waveform which is the output of the RS flip-flop 14 is set to the high level in accordance with the change of the low level of the i-point waveform at time T21. On the other hand, the time of the j-point waveform
The k-point waveform is reset to the low level according to the change to the low level at T22. After that, similarly, the k-point waveform is
Time T23 and time T depending on changes in the i-point waveform and the j-point waveform
At 24 and time T25, setting and reset are repeated.
The k-point waveform output from the RS flip-flop 14 is NO
It is inverted by the action of the T circuit 49 and is output as an m-point waveform which is a wheel-to-vehicle body relative speed polarity signal.

Next, the operation of the shock absorber control device 1 described above will be described with reference to the timing chart of FIG. As shown in FIG. 8, the operation shown in FIG. 7 is performed by the hydraulic vibration exciter 51 with respect to the wheels 2 in the directions indicated by arrows A and B.
This is the case where vibration of 1.5 [Hz] amplitude ± 10 [mm] is applied.

As shown in FIG. 7, when the vibration of the wheel 2 is started, the wheel-to-vehicle body relative speed polarity signal generation circuit 9 outputs a wheel-to-vehicle body relative speed polarity signal (m-point waveform in FIG. 2), A vehicle body-to-road surface relative velocity polarity signal generation circuit 10 inputs a vehicle body-to-road surface relative velocity polarity signal (waveform of point d in FIG. 2) to a damping force switching signal generation circuit 11. The damping force switching signal generation circuit 11
Is a hard switching signal (waveform p in FIG. 2) and a soft switching signal (waveform a in FIG. 2) according to both the input signals.
Is output to the drive circuit 12, and the drive circuit 12 causes the motor 6 to normally rotate in response to the hardware switching signal and reversely rotates in response to the software switching signal to reduce the damping force of the shock absorber 5 in two stages. Switch. That is, at time T31, both the wheel-to-vehicle body relative speed polarity signal and the vehicle-to-road surface relative speed polarity signal are in high-level in-phase.
The hardware switching signal is output (ON) from T31 to time T32 after a predetermined time. On the other hand, at time T33, the wheel-to-vehicle body relative speed polarity signal is at a high level, but the vehicle body-to-road surface relative speed polarity signal changes to a low level, and the both polarity signals are in opposite phases. The soft switching signal is output (ON) until time T34 later. After that, when the bipolar signals have the same phase, the hard switching signal is output, and when the bipolar signals have the opposite phase, the soft switching signal is output for a predetermined time.

In this embodiment, the acceleration sensor 8 functions as an acceleration detecting means, the sample hold circuit 16 functions as a holding means, and the comparator 17 functions as a comparing means.

According to the present embodiment having the above-mentioned configuration, the phase difference with respect to the vertical acceleration of the vehicle body can be obtained even if the frequency of the vehicle body guidance changes with a simple configuration including the acceleration sensor 8, the sample hold circuit 16 and the comparator 17. It is possible to obtain a vehicle body-to-road surface relative velocity polarity signal that does not occur.

Further, since the normal operation can be performed only by adjusting the values of the input resistances 32 and 33 of the comparator 17 in the vehicle body-to-road surface relative velocity polarity signal generation circuit 10, the adjustment man-hour and the manufacturing cost can be reduced, and the vehicle body pairing can be reduced. Road surface relative velocity polarity signal generation circuit
10 reliability is also improved.

Further, the rotary encoder 7, the phase discriminator 13 and the RS
With a simple configuration including the flip-flop 14, even when vibrations of various frequencies are applied to the wheels, it is possible to obtain a wheel-to-vehicle relative velocity polarity signal that does not cause a phase difference with respect to displacement between the vehicle body and the wheels.

Further, since the wheel-to-vehicle body relative velocity polarity signal generation circuit 9 is configured by the combination of the phase discriminator 13 and the RS flip-flop 14, it is not necessary to adjust the circuit elements, the manufacturing man-hour and the manufacturing cost can be reduced, and the wheel The reliability of the vehicle relative velocity polarity signal generation circuit 9 is also improved.

Further, since the wheel-to-vehicle relative velocity polarity signal that does not cause a phase difference with respect to the displacement between the wheel and the vehicle body and the vehicle-to-road surface relative velocity polarity signal that does not cause a phase difference with respect to the vertical acceleration of the vehicle body are obtained. By using the above-mentioned bipolar signal, it is possible to suitably perform shock absorber damping force switching control for the purpose of suppressing vehicle body vibration based on the principle of skyhook. That is, it is possible to realize control in which the damping force is switched to two levels, high and low, for each cycle of each vibration of the wheel and the vehicle body.

Although the embodiments of the present invention have been described above, the present invention is not limited to such embodiments, and it is needless to say that the present invention can be implemented in various modes without departing from the scope of the present invention. .

Effect 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 polarity signal output from the second polarity signal generating means is influenced by the fluctuation of the vibration frequency of the vehicle body. It is possible to always have the same phase as the vehicle body acceleration. Therefore, the damping force switching means for switching the damping force of the shock absorber on the basis of this polarity signal and the polarity signal output from the first polarity signal generating means causes the shock absorber for each cycle of each vibration of the wheel and the vehicle body. The damping force control for switching the damping force of 2 between high and low can be executed with high accuracy in accordance with the behavior of the vehicle body, and the vehicle body vibration can be suppressed well.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a vehicle-to-road surface relative velocity polarity signal generation circuit according to an embodiment of the present invention, FIG. 2 is a system configuration diagram of a shock absorber controller, and FIG. 3 is a vehicle-to-road surface relative velocity polarity signal generation circuit. Timing chart showing the operation of the circuit, FIG. 4 is a circuit diagram showing the wheel-to-vehicle relative velocity polarity signal generating circuit, FIGS. 5 and 6 are timing charts showing the same operation, and FIG. 7 is a shock absorber control device. FIG. 8 is a timing chart showing the operation of FIG. 5 ... shock absorber, 6 ... motor 7 ... rotary encoder, 8 ... acceleration sensor 9 ... wheel-to-vehicle relative velocity polarity signal generation circuit 10 ... vehicle-to-road surface relative velocity polarity signal generation circuit 11 ... damping force Switching signal generation circuit 12 …… Drive circuit, 13 …… Phase discriminator 14 …… RS flip-flop 16 …… Sample hold circuit 17 …… Comparator

Claims (1)

[Scope of utility model registration request] 1. A displacement detection means for detecting relative displacement between a wheel and a vehicle body, and a wheel-to-vehicle body relative speed indicating whether the wheel and the vehicle body are approaching or moving away from each other, based on a detection signal from the displacement detection means. First polarity signal generating means for generating a polarity signal, acceleration detecting means for detecting the vertical acceleration of the vehicle body and outputting an acceleration signal, and sampling the acceleration signal output from the acceleration detecting means at a predetermined cycle. The holding means for holding and the acceleration signal held by the holding means and the acceleration signal output from the acceleration detecting means are compared in magnitude, and whether the vehicle body and the road surface are approaching or moving away from each other is indicated based on the comparison result. When the second polarity signal generating means for generating the polarity signal of the vehicle body-to-road surface relative speed and the respective polarity signals output from the respective polarity signal generating means have the same phase, A damping force control device for a vehicle shock absorber, comprising: damping force switching means for increasing the damping force of the absorber and reducing the damping force of the shock absorber when the polarity signals have opposite phases. .