JPH08230432A - Damping force controller for vehicle - Google Patents

Abstract

PURPOSE: To improve controllability for suppressing damping force by controlling an oscillation detecting means according to a vehicle speed and shifting the predetermined frequency range in a vibration detecting means to a high frequency side according to the increase in the vehicle speed in a controller in which a damping force generating mechanism is controlled according to a vibration constituent in a spring upper member. CONSTITUTION: In shock absorbers 11-14 serving as damping force generating mechanisms, by controlling actuators 11a-14a built in the shock absorbers 11-14, generated damping force is controlled so as to be switched to three levels, in other words, to a high level, an intermediate level, and a low level. In this case, the first vibration constituent G1 related to a drive of a spring upper member is low-pass filter processed on the basis of outputs from acceleration sensors 21a-21d built in the spring upper member so as to be detected, while the second vibration constituent G2 is band-pass filter processed so as to be detected, and the generated damping force is increased according to increase of the first vibration constituent G1 and is reduced according to increase of the second vibration constituent G2. Then, central frequency of the band-pass filter is shifted to the high frequency side according to increase in a vehicle speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention controls a damping force generating mechanism for generating a damping force which is provided between a sprung member and an unsprung member to damp the vibration of the sprung member with respect to the unsprung member. And a control device for controlling the damping force generation mechanism in accordance with the vibration component of the sprung member having a frequency between the resonance frequency of the sprung member and the resonance frequency of the unsprung member, which gives an occupant a discomfort. The present invention relates to a damping force control device.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Laid-Open No. 2-14132.
As disclosed in Japanese Unexamined Patent Application Publication No. 0-202, the vibration component of the sprung member belonging to the frequency range near the resonance frequency of the sprung member (about 1 to 2 Hz) and the frequency range near the resonance frequency of the unsprung member (10 to 12 Hz) The vibration component of the unsprung member that belongs to the frequency range and the frequency range (about 3 to 8 Hz) between the resonant frequency of the sprung member and the resonant frequency of the unsprung member belong to the occupant and the passenger feels uncomfortable. ), The vibration components of the sprung member are independently detected, and the damping force generation mechanism (shock absorber) dampens the maneuverability and ride comfort of the vehicle based on these vibration components. It is known to control the magnitude of force.

[0003]

The vibration component in the frequency range near the resonance frequency of the sprung member and the vibration component in the frequency range near the resonance frequency of the unsprung member do not change so much even if the vehicle speed changes, but The frequency range of the vibration component of the sprung member that causes discomfort changes depending on the vehicle speed for the following reason. This vibration component becomes maximum when the front and rear wheels move up and down in the same phase due to road surface input, so it becomes maximum when the cycle of the vibration component and the time when the vehicle travels the same distance as the wheel base match. Becomes
In other words, when the frequency of the vibration component is f, the wheel base is L, and the vehicle speed is V, the vibration component that gives the occupant an uncomfortable feeling becomes maximum at a frequency at which the relationship of f = V / L is established. This indicates that the center frequency f of the vibration component shifts to the higher frequency side as the vehicle speed V increases (see FIG. 8).

However, in the above-mentioned conventional apparatus, the frequency range in which the vibration component of the sprung member which gives an occupant annoyance is detected is always fixed. For optimum riding comfort
It is not possible to control the magnitude of the damping force by the damping force generation mechanism.

[0005]

As described above, the vibration component of the vehicle due to the road surface input is, as shown in FIG. 8, a sprung member belonging to a frequency range (about 1 to 2 Hz) near the resonance frequency of the sprung member. The first vibration component G1 of the member, which belongs to the frequency range (about 3 to 8 Hz) between the resonance frequency of the sprung member and the resonance frequency of the unsprung member, and gives the occupant an unpleasant feeling (the occupant feels lumpy). 2 vibration components G2,
And the frequency range near the resonance frequency of the unsprung member (10 to 10
The third vibration component G3 of the unsprung member belonging to 12 Hz)
And the second vibration component G2 of them has the property of shifting to the high frequency side as the vehicle speed increases as described above. Further, since the frequency range of each of these vibration components G1 to G3 is not clearly defined, when the second vibration component G2 shifts to the high frequency side due to the increase in vehicle speed as described above, the third vibration component G3 is generated. 2nd and 3rd by mixing with
It becomes difficult to detect the vibration components G2 and G3 separately. Also,
Normal (set the wheelbase to about 2.6m, for example)
The second vibration component G2 becomes maximum at a vehicle speed of about 50 to 60 Km / h, increases to some extent up to a vehicle speed of 70 to 80 Km / h, but becomes extremely small at a speed exceeding 80 Km / h.

It is necessary to appropriately set the damping force for each of these vibration components. Since the first vibration component G1 causes tilting of the sprung member (vehicle body), this first vibration component G1 is used in order to maintain the steering stability of the vehicle.
It is necessary to increase the damping force for the increase of. Second
Since the vibration component G2 makes the occupant feel rugged, in order to improve the ride comfort of the occupant, this second component is used.
It is necessary to suppress the damping force to be small with respect to the increase of the vibration component G2 of. Since the third vibration component G3 means the vibration of the unsprung member (wheel), it is necessary to increase the damping force with respect to the increase of the third vibration component G3 in order to maintain the steerability of the vehicle. There is.

An object of the present invention is to focus on the second vibration component G2 of the above-mentioned vibration components so that the control for suppressing the damping force due to the same component G2 can be accurately performed.

[0008]

In order to achieve the object of the present invention, the first structural feature of the present invention is that the predetermined frequency set between the resonance frequency of the sprung member and the resonance frequency of the unsprung member. Component of the sprung member belonging to the frequency range of
Vibration detecting means for detecting the vibration component G2) and a damping force for controlling the damping force generation mechanism according to the detected vibration component to suppress the damping force generated by the damping force generation mechanism as the vibration component increases. In a vehicle damping force control device including a control means, a vehicle speed is detected, and a predetermined frequency range in the vibration detection means is shifted to a higher frequency side as the detected vehicle speed increases. . As a result, according to the first structural feature, the second vibration component G that shifts to the high frequency side according to the vehicle speed.
Since the above-described property of 2 is taken into consideration, the second vibration component G2 can be accurately detected, the damping force for the second vibration component G2 is accurately controlled, and the ride comfort of the vehicle is improved. .

The second structural feature is that the vehicle speed is detected by detecting the vehicle speed, and the damping force control means is used to detect the degree of the generated damping force that can be suppressed to a smaller value as the detected vibration component increases. It is configured so as to relax as the value becomes larger. As a result, according to the second structural feature, even if the vehicle speed increases and the third vibration component G3 is mixed in the second vibration component G2, the control for suppressing the damping force generated by the second vibration component G2 to be small. Is alleviated. Therefore, the control of the damping force with respect to the second vibration component G2 is accurately performed, and the ride comfort of the vehicle is improved.

The third structural feature is that the vibration component near the resonance frequency of the unsprung member (third vibration component G3) is detected, and the damping force control means makes the detected vibration component large. It is configured such that the degree of the generated damping force that can be suppressed to a smaller value is alleviated as the detected vibration component near the resonance frequency of the unsprung member increases. As a result, according to the third structural feature, the vehicle speed is increased and the third vibration component G3 is changed to the second vibration component G3.
If it is mixed in 2, the control for suppressing the damping force generated by the second vibration component G2 is relaxed according to the magnitude of the third vibration component G3. Therefore, the control of the damping force with respect to the second vibration component G2 is accurately performed, and the ride comfort of the vehicle is improved.

Further, in addition to the third structural feature, the fourth structural feature is that the vehicle speed is detected and the damping force control means is suppressed to a smaller value as the detected vibration component increases. The degree of the generated damping force generated is alleviated by increasing the detected vehicle speed. As a result, according to the fourth structural feature, the second vibration component G2 that decreases as the vehicle speed increases.
Is detected more accurately, and the damping force for the second vibration component G2 is controlled more accurately than in the case of the third structural feature, so that the riding comfort of the vehicle is improved.

[0012]

【Example】

a. First Embodiment First, a first embodiment according to the first feature of the present invention will be described with reference to the drawings. FIG. 1 schematically shows a vehicle damping force control device according to the present invention. This damping force control device includes shock absorbers 11 to 11 as a damping force generating mechanism.
It controls the damping force generated by 14, and comprises acceleration sensors 21a to 21d, a vehicle speed sensor 22 and a microcomputer 23.

The shock absorbers 11 to 14 are provided between the sprung member (vehicle body) and the unsprung member (wheel) at each wheel position, and are for damping the vibration of the sprung member with respect to the unsprung member. Generate force. The actuators 11a to 14a are incorporated in the shock absorbers 11 to 14, respectively.
4a controls the generated damping force by switching among three levels of "large", "medium", and "small".

The acceleration sensors 21a to 21d are respectively mounted on sprung members corresponding to the shock absorbers 11 to 14, respectively, to detect the vertical acceleration G of the sprung members, and to detect the detected acceleration G. The signals are output to the microcomputer 23, respectively. The vehicle speed sensor 22 detects the vehicle speed V by measuring the rotation of an output shaft of a transmission or the like, and outputs a detection signal representing the detected vehicle speed V. The microcomputer 23 executes the program represented by the flowchart shown in FIG. 2 for each wheel to drive and control the actuators 11a to 14a in the shock absorbers 11 to 14, respectively.

Next, the operation of the first embodiment constructed as described above will be explained. First, only the control of the shock absorber 11 will be described. In response to the turning on of the ignition switch, the microcomputer 23 causes the step 1
At 00, execution of the program is started. After starting the execution of this program, in step 102 the acceleration sensor 21a
And the respective detection signals representing the acceleration G and the vehicle speed V detected by the vehicle speed sensor 22. Next, step 10
At 4, the acceleration G is subjected to a low-pass filter process with a cutoff frequency of approximately 2 Hz to calculate a first vibration component G1 related to the swing vibration of the sprung member.

Next, at step 106, it is judged whether or not the vehicle speed V is lower than a predetermined vehicle speed Vm (for example, 80 km / h). If V <Vm, the processes of steps 108 and 110 are executed. In step 108, the vehicle speed V is divided by a predetermined wheel base L of the vehicle to calculate the center frequency f (= V / L) of the second vibration component G2. In step 110, using the calculated center frequency f, the parameter b in the transfer function F (S) of the following equation 1 is calculated as b = (2πf) ² .

[0017]

[Formula 1] F (S) = a · S / (S ² + a · S + b) The transfer function F (S) of Formula 1 is a band-pass filter process that makes the pass band of the input signal approximately between 3 and 8 Hz. In the same number 1, a is a predetermined constant that determines the signal pass bandwidth of the bandpass filter, and S is a Laplace operator. Step 108,
After the processing of 110, the bandpass filter processing is performed on the acceleration G by executing the calculation of the following mathematical expression 2 using the input acceleration G in step 114, and the second generated in the vehicle in response to the road surface input. Calculate the vibration component G2.

[0018]

As a result, the second vibration component G2 is detected by the bandpass filter processing in which the center frequency f is shifted to the high frequency side as the vehicle speed V increases. .

On the other hand, if V ≧ Vm, step 11
Through the processing of 2,114, the pass frequency band is 3 to 8 Hz
The second acceleration component G2 is calculated by subjecting the detected acceleration G to a fixed band-pass filter process. This is the second
This is because the vibration component G2 decreases when the vehicle speed V exceeds 80 km / h, but does not disappear at all when the vehicle speed V exceeds 80 km / h.

After calculating the first and second vibration components G1 and G2, in step 116, the calculated second vibration component G is calculated.
The upper limit value UM of the damping force is determined according to the magnitude (amplitude) of 2. In this case, the second vibration component G2 is compared with the predetermined first and second reference values G2ref1, G2ref2 (G2ref1 <G2ref2), and if G2≤G2ref1, UM = 3, G2ref1.
<G2 ≤ G2ref2, UM = 2; G2ref2 <G2, U
Let M = 1. In this case, UM = 1 has a small damping force,
UM = 2 indicates that the damping force is “medium”, and UM = 3 indicates that the damping force is “large”.

Next, at step 118, the damping force X is determined according to the magnitude (amplitude) of the calculated first vibration component G1. The first vibration component G1 is compared with predetermined first and second reference values G1ref1, G1ref2 (G1ref1 <G1ref2), and if G1≤G1ref1, X = 1, G1ref1 <G1≤G
If 1ref2, X = 2; if G1ref2 <G1, X = 3. After the processing of step 118, steps 120 and 1
By the process of 22, the upper limit value of the damping force X determined according to the first vibration component G1 is limited to the upper limit value UM determined according to the second vibration component G2. That is, X> UM
If so, set X = UM again. As a result, the final determined damping force X is as shown in Table 1 below.

[0022]

[Table 1]

After the processing of steps 120 and 122, the damping force generated by the shock absorber 11 by the processing of steps 124 to 134 is controlled to the damping force X whose upper limit is limited. If the damping force X is "1", it is judged "YES" in step 124 and the program is returned to step 102, so that the shock absorber 11 is in the initial state (soft state) of the damping force "small". Maintained.

On the other hand, if the determined damping force X is "2" or "3", it is determined to be "NO" at step 124 and the program proceeds to step 126 and thereafter. In step 126, if the determined damping force X is "2", the holding time Tx is set to the first predetermined time T1, and if the determined damping force X is "3", the holding time Tx is set from the first predetermined time T1. Set to a large second predetermined time T2. Then, step 128
At the actuator 1, a control signal representing the determined damping force X is transmitted.
Output to 1a. Since the actuator 11a controls the generated damping force of the shock absorber 11 to the determined damping force X, if the determined damping force X is "2", the generated damping force of the absorber 11a is set to "medium". If the determined damping force X is "3", the shock absorber 11a
The generated damping force of is set to "large" (hard state).

After the processing of step 128, step 1
After waiting the elapse of the set holding time Tx at 30, the program proceeds to steps 132 and 134. In steps 132 and 134, the determined damping force X is returned to "1" and a control signal representing the determined damping force X returned to "1" is output to the actuator 11a. As a result, the damping force generated by the shock absorber 11 is returned to "small". Therefore, if the determined damping force X is "2" or "3", the shock absorber 1 is held for the holding time Tx corresponding to the damping force X.
The generated damping force of 1a is controlled to "medium" or "large".

Then, after the damping force generated by the shock absorber 11 is returned to "small", the above steps 102-
By repeating the circulation process consisting of 134, the damping force generated by the shock absorber 11 is started to be controlled again according to the acceleration G and the vehicle speed V. Although the above description relates to the shock absorber 11, the shock absorber 12 to
Regarding 14 as well, it is controlled in the same manner as above. However, in this case, the acceleration G is the acceleration sensors 21b to 21d.
The one detected by is used.

In this way, the shock absorber 11
As a result of controlling the generated damping force of Nos. 14 to 14, the damping force control device according to the first embodiment detects the first vibration component G1 by the processing of step 104, and steps 118, 1
By the processing of 24 to 134, the damping force of the shock absorbers 11 to 14 is controlled to the larger side as the first vibration component G1 increases, and the swinging vibration of the sprung member related to the vibration component G1 is well suppressed. To be done. On the other hand, by the processing of steps 114, 116, 120 and 122,
The damping force controlled by the first vibration component G1 is the second
Since the vibration component G2 is suppressed to the smaller side as it increases, the ride comfort of the vehicle is also kept good. Further, by the processing of steps 108, 110 and 114, the second vibration component G2 of the vehicle with respect to the road surface input is shifted to the higher frequency side as the vehicle speed V increases, so that the second vibration component G2 is accurately detected. The suppression control by the second vibration component G2 of the generated damping force is accurately performed. As a result, according to the first embodiment, the controllability and ride comfort of the vehicle are controlled in a well-balanced manner.

In the first embodiment, the upper limit value of the damping force X determined according to the first vibration component G1 is regulated by the processing of steps 120 and 122. A map such as that shown in FIG.
By the map reference process instead of the process of 122, the first
The final damping force X may be determined according to the determined damping force X by the vibration component G1 and the upper limit value UM determined by the second vibration component G2.

B. Second Embodiment Next, a second embodiment according to the second feature of the present invention will be described. The second embodiment is configured similarly to the first embodiment as shown in FIG. 1, but the microcomputer 23 according to the same embodiment corresponds to the flow chart shown in FIG. 3 for each shock absorber 11-14. Run the program you made. In the flowchart of FIG. 3, the same processes as those in the first embodiment are designated by the same reference numerals as those in the first embodiment. Next, the operation of the damping force control system according to the second embodiment will be described. The shock absorbers 11-14
Are controlled in the same way, the shock absorber 11
Only the other shock absorbers 12 to
The description of 14 is omitted.

The microcomputer 23 inputs the acceleration G and the vehicle speed V in step 102 and step 10
After the calculation of the first vibration component G1 of No. 4, in step 200, a fixed bandpass filter process for setting the pass frequency band to about 3 to 8 Hz is applied to the detected acceleration G2 to calculate the second vibration component G2. In this case also, the calculation of the above-mentioned mathematical expression 2 is executed, but the transfer function F expressed by the mathematical expression 1 of the same mathematical expression 2 is expressed.
Each parameter a and b in (S) is a fixed value stored in advance in the microcomputer 23.

Next, referring to a built-in two-dimensional map (characteristic graph of FIG. 4) based on the magnitude (amplitude) of the second vibration component G2 and the vehicle speed V calculated in step 212, the second vibration is referred to. A region defined by the component G2 and the vehicle speed V is searched for, and the upper limit value UM of the damping force is set to values "1" to "3" corresponding to the searched region. In this case, as is clear from the characteristic graph of FIG. 4, the upper limit value UM is the second vibration component G2.
Is set to a smaller value as is increased, and is set to a larger value as the vehicle speed V is increased.

After the processing of step 212, step 1
At 18, the damping force X is set to "1", "2" or "3" according to the magnitude (amplitude) of the first vibration component G1 as described above. Then, by the same processing of steps 120 and 122 as in the first embodiment, the first vibration component G
The upper limit value of the damping force X determined according to the magnitude of 1 is limited to the upper limit value UM determined according to the second vibration component G2. As a result, also in this case, the final determined damping force X is as shown in Table 1 above. Then, steps 124 to 134
By the processing of (1), the generated damping force of the shock absorber 11 is set to the limited final determined damping force X.

In this way, the shock absorber 11
As a result of controlling the generated damping force of Nos. 14 to 14, the damping force control device according to the second embodiment detects the first vibration component G1 by the processing of step 104, and steps 118, 1
By the processing of 24 to 134, the damping force of the shock absorbers 11 to 14 is controlled to the larger side as the first vibration component G1 increases, and the swinging vibration of the sprung member related to the vibration component G1 is well suppressed. To be done. On the other hand, the second vibration component G2 is detected by the process of step 200, and the damping forces of the shock absorbers 11 to 14 controlled by the first vibration component G1 are the second vibration component by the processes of steps 212, 120 and 122. As G2 increases, it is suppressed to the smaller side, and this second
The control for suppressing the damping force by the vibration component G2 is alleviated as the vehicle speed V increases. Therefore, even if the vehicle speed V increases and the third vibration component G3 is mixed in the second vibration component G2, the damping force for the second vibration component G2 is accurately controlled and the ride comfort of the vehicle is kept good. Be drunk As a result, also in the second embodiment described above, the controllability and ride comfort of the vehicle are controlled in a well-balanced manner.

In the second embodiment as well, as in the case of the first embodiment, instead of the processing of steps 120 and 122, the map as shown in Table 1 is referred to so that the first Damping force X determined by vibration component G1 and damping force X determined by second vibration component G2 and vehicle speed V
The final damping force X may be determined according to the upper limit value UM of

C. Third Embodiment Next, a third embodiment according to the third feature of the present invention will be described. As shown in FIG. 1, the third embodiment includes wheel speed sensors 24a to 24d, which detect the wheel speeds Vr of the respective wheels, instead of the vehicle speed sensor 22. Further, the microcomputer 23 uses the shock absorbers 11 to 1
The program corresponding to the flowchart shown in FIG. In addition, in the flowchart of FIG.
The same processes as those in the first embodiment are designated by the same reference numerals as those in the first embodiment. Next, the operation of the damping force control system according to the third embodiment will be described. In this case as well, only the shock absorber 11 will be described, and description of the other shock absorbers 12-14 will be omitted.

The microcomputer 23 executes the step 3
After the execution of the program of 00, the acceleration G and the wheel speed Vr are input from the acceleration sensor 21a and the wheel speed sensor 24a corresponding to the shock absorber 11 in step 302, and the processes of steps 304 to 308 are executed. In step 304, the pass frequency band is 1-2 Hz
The detected acceleration G is subjected to a fixed band-pass filtering process to a degree to calculate the first vibration component G1 near the resonance frequency of the sprung member. In step 306,
A fixed band-pass filter process having a pass frequency band of about 3 to 8 Hz is applied to the detected wheel speed Vr to calculate the second vibration component G2 of the sprung member which gives an occupant an unpleasant feeling. In step 308, a fixed bandpass filter process having a pass frequency band of about 10 to 15 Hz is applied to the detected wheel speed Vr to calculate a third vibration component G3 near the resonance frequency of the unsprung member. In these cases as well, the same calculation as in the above-mentioned mathematical expression 2 is executed, but the parameters a and b of the transfer function F (S) expressed in the mathematical expression 1 in the mathematical expression 2 are stored in advance in the microcomputer 23. It is a fixed value.

After the steps 304 to 308, in step 310, the first and second vibration components G1 are referred to by referring to the two-dimensional map shown in Table 2 below based on the first and second vibration components G1 and G2. , G2 according to the magnitude of G2.

[0038]

[Table 2]

G1ref1, G1ref2 (G1ref1 <in Table 2 above
G1ref2) and G2ref1, G2ref2 (G2ref1 <G2ref2)
Are reference values determined in advance. After the processing of step 310, the magnitude (amplitude) of the third vibration component G3 near the resonance frequency of the unsprung member is compared with a predetermined threshold value S0 at step 312, and if G3 <S0, the program is stepped. Proceed to 124. If G3 ≧ S0, the program proceeds to steps 314 and 316, and the same step 3
The damping force X determined by the processing of 14, 316 is limited to the lower limit value LM or more. This lower limit value LM is predetermined and is set to "2" in this embodiment. Therefore, when the third vibration component G3 is small, the determined damping force X can take values of "1" to "3", but when the third vibration component G3 becomes large, the above-mentioned determination damping force X becomes large even if the second vibration component G2 becomes large. The determined damping force X is limited to "2" or "3". The lower limit value LM may be set to "3".
Then, the damping force generated by the shock absorber 11 is set to the determined damping force X by the processing in steps 124 to 134 described above.

As described above, according to this third embodiment,
By the processing of steps 304 and 306, the first and second vibration components G1 and G2 are detected, and steps 310 and 1
By the processing of 24 to 134, the shock absorber 11 to 11
The generated damping force of 14 is controlled so as to increase as the first vibration component G1 increases and decrease as the second vibration component G2 increases. Therefore, the swinging vibration of the sprung member related to the first vibration component G1 is suppressed well in consideration of the occupant's discomfort caused by the second vibration component G2. On the other hand, while the third vibration component G3 is detected by the processing of step 308,
By the processing of 12 to 316, when the third vibration component G3 is the threshold value S0 or more, the shock absorber 11 is used.
It is regulated that the damping forces of 14 are set small.
Therefore, the third vibration component G3 that increases as the vehicle speed V increases is more accurately taken into consideration, and the first and second vibration components G3 and
The damping force with respect to the vibration components G1 and G2 is accurately controlled, so that the steerability and riding comfort of the vehicle are controlled in a well-balanced manner. .

(Modification) Next, a modification of the third embodiment according to the fourth feature of the present invention will be described. This modification has the same configuration as that of the third embodiment, but the microcomputer 23 includes shock absorbers 11-14.
The program corresponding to the flowchart shown in FIG. 6 is executed every time. In the flowchart of FIG. 6, the same processes as those in the first and third embodiments are designated by the same reference numerals as those in the first and third embodiments. Next, the operation of the damping force control device according to this modification will be described. In this case as well, only the shock absorber 11 will be described, and description of the other shock absorbers 12 to 14 will be omitted.

In this modification, after starting the program in step 300, the acceleration G is input from the acceleration sensor 21a corresponding to the shock absorber 11 in step 302a, and the wheel speed Vr of each wheel is set.
(4 wheel speeds Vr) are input respectively. Next, in step 320, the vehicle speed V is calculated by calculating the average value of the four wheel speeds Vr. Then, after the first to third vibration components G1, G2, G3 are calculated and the damping force X is determined by the processing of steps 304 to 310 described above, the built-in map is determined in step 322 according to the calculated vehicle speed V. With reference to FIG. 7, a threshold value S that decreases as the vehicle speed V increases is determined. Next, in step 324, the magnitude (amplitude) of the third vibration component G3 is compared with the threshold value S determined above, and if G3 <S, the program proceeds to step 124. If G3 ≧ S, the damping force X determined by the processing of steps 314 and 316 is limited to the lower limit value LM or more. And
Through the processing of steps 124 to 134, the damping force generated by the shock absorber 11 is set to the limited final determined damping force X.

In this way, the shock absorber 11
As a result of controlling the generated damping force of Nos. 14 to 14, according to the damping force control device of this modified example, in addition to the third embodiment, the threshold value that decreases as the vehicle speed V increases due to the process of step 324. S is determined, step 32
By the processing of 4,314,316, the third vibration component G
When 3 is equal to or greater than the threshold value S, it is restricted that the damping force of the shock absorbers 11 to 14 is set small. Therefore, the third vibration component G3, which increases as the vehicle speed V increases, is more accurately taken into consideration.
Further, the damping force for the second vibration components G1 and G2 is controlled more accurately, and the steerability and riding comfort of the vehicle are controlled in a more balanced manner.

In the first to third embodiments and the modifications of the third embodiment, the shock absorbers 11 to 14 are used.
Although the number of switching stages is set to 3, the number of stages can be further increased to perform more detailed control.

[Brief description of drawings]

FIG. 1 is a block diagram schematically showing a damping force control device for a vehicle according to each embodiment of the present invention.

FIG. 2 is a flowchart of a program executed by the microcomputer of FIG. 1 according to the first embodiment of the present invention.

FIG. 3 is a flowchart of a program executed by the microcomputer of FIG. 1 according to the second embodiment of the present invention.

FIG. 4 is a graph showing a region of an upper limit value UM defined according to a second vibration component G2 and a vehicle speed V.

FIG. 5 is a flowchart of a program executed by the microcomputer of FIG. 1 according to the third embodiment of the present invention.

FIG. 6 is a flowchart of a program executed by the microcomputer of FIG. 1 according to a modification of the third embodiment.

FIG. 7 is a graph showing a change characteristic of a threshold value S with respect to a vehicle speed V.

[FIG. 8] First to third generated in a vehicle in response to road surface input
6 is a graph showing a distribution state of vibration components G1 to G3.

[Explanation of symbols]

11-14 ... Shock absorber, 11a-14a ... Actuator, 21a-21d ... Acceleration sensor, 22 ...
Vehicle speed sensor, 23 ... Microcomputer, 24a-2
4d ... A wheel speed sensor.

Claims (4)

[Claims] 1. A vehicle provided with a damping force generating mechanism for generating a damping force provided between an unsprung member and an unsprung member to damp vibration of the unsprung member with respect to the unsprung member, Vibration detection means for detecting a vibration component of the sprung member belonging to a predetermined frequency range set between the resonance frequency of the sprung member and the resonance frequency of the unsprung member, and the damping force generation according to the detected vibration component In a vehicle damping force control device that includes a damping force control unit that controls the mechanism to reduce the damping force generated by the damping force generation mechanism as the vibration component increases, a vehicle speed detection unit that detects the vehicle speed; Transition control for controlling the vibration detecting means in accordance with the detected vehicle speed and shifting a predetermined frequency range in the vibration detecting means to a high frequency side as the detected vehicle speed increases. And a damping force control device for a vehicle. 2. A vehicle provided with a damping force generating mechanism for generating a damping force provided between an unsprung member and an unsprung member to damp vibration of the unsprung member with respect to the unsprung member, Vibration detection means for detecting a vibration component of the sprung member belonging to a predetermined frequency range set between the resonance frequency of the sprung member and the resonance frequency of the unsprung member, and the damping force generation according to the detected vibration component A vehicle speed detecting means for detecting a vehicle speed is provided in a vehicle damping force control device including a damping force control means for controlling the mechanism to reduce the damping force generated by the damping force generating mechanism as the vibration component increases The damping force control means reduces the degree of the generated damping force that can be suppressed to a smaller value as the detected vibration component increases as the detected vehicle speed increases. A damping force control device for a vehicle, which is configured. 3. A vehicle equipped with a damping force generation mechanism for generating a damping force that is provided between an unsprung member and an unsprung member to damp vibration of the unsprung member with respect to the unsprung member. Vibration detection means for detecting a vibration component of the sprung member belonging to a predetermined frequency range set between the resonance frequency of the sprung member and the resonance frequency of the unsprung member, and the damping force generation according to the detected vibration component A damping force control device for a vehicle, comprising: a damping force control means for controlling the mechanism to reduce the damping force generated by the damping force generation mechanism as the vibration component increases; An unsprung component detecting means for detecting a component is provided, and the damping force control means detects the degree of the generated damping force which is suppressed to be smaller as the detected vibration component becomes larger. A damping force control device for a vehicle, characterized in that it is configured so as to reduce as the vibration component near the resonance frequency of the lower member increases. 4. A vehicle provided with a damping force generating mechanism for generating a damping force provided between an unsprung member and an unsprung member to damp the vibration of the unsprung member with respect to the unsprung member, Vibration detection means for detecting a vibration component of the sprung member belonging to a predetermined frequency range set between the resonance frequency of the sprung member and the resonance frequency of the unsprung member, and the damping force generation according to the detected vibration component A damping force control device for a vehicle, comprising: a damping force control means for controlling the mechanism to reduce the damping force generated by the damping force generation mechanism as the vibration component increases; An unsprung component detecting means for detecting a component, a vehicle speed detecting means for detecting a vehicle speed, and the damping force control means,
The degree of the generated damping force, which is suppressed to be smaller as the detected vibration component becomes larger, is mitigated as the detected vibration component near the resonance frequency of the unsprung member becomes larger and as the detected vehicle speed becomes larger. A damping force control device for a vehicle having the above-mentioned configuration.