JPH03148317A - Suspension controller - Google Patents

Abstract

PURPOSE:To prevent impact surely, by extracting an on-spring resonance component from the detection signal of a vibration condition generated at a vehicle, and practicing the prevention of impact in the case of this on-spring resonance component having become out of an allowable range that is determined according to a car speed. CONSTITUTION:The above suspension controller is equipped with a vibration condition detecting means M1 which detects the condition of vibration generated at a vehicle due to the change of a road surface, and changes the damping force characteristic of a shock absorber M2 on the basis of its detection signal, and restrains the vibration of a car body. In this instance, provided are an on-spring resonance component extracting means M3 which extracts the vicinity frequency component of an on-spring resonance frequency from the vibration condition detection signal, and a car speed detecting means M4. And the allowable range of the size of the on-spring resonance component is operated by means of an allowable range operating means M5 according to a car speed, and at the same time, in the case of the extracted on-spring resonance component having become out of the allowable range, it is so arranged that the damping force degree of the shock absorber M2 is heightened by means of a high damping force maintaining means M6.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a suspension control device, and more specifically, the present invention relates to a suspension control device that detects the state of vibration generated in a vehicle due to changes in the road surface, and detects the state of vibration generated in a vehicle due to changes in the road surface, and controls the system based on the detected state of vibration. The present invention relates to a suspension control device that suppresses vehicle body vibration by changing the damping force characteristics of a shock absorber. [Prior art] The [tilt] of a vehicle, that is, the cycle is relatively long, about 1 second,
As a device for preventing vehicle vibrations that cause car sickness, etc., there is a suspension control device described in Japanese Patent Application Laid-Open No. 62-80111. If tilting is detected, the damping force generation pattern of the shock absorber is set to the high damping force side to make the suspension harder, thereby preventing tilting. To detect (1) when the frequency of the friend vehicle height change is near the sprung mass resonance frequency (frequency 1, O [around 1 Hz) and the magnitude of the vehicle height change exceeds a preset threshold
[Problem to be Solved by the Invention] The above structure is excellent in preventing the vehicle from tilting, but depending on the driving condition, the vehicle may be tilted. For example, when driving at high speeds, drivers tend to be more sensitive to tailgating behavior than when driving at low speeds. Sometimes it feels big. Therefore, if the threshold value for vehicle height change is set based on low-speed driving, the sensory evaluation will show that the anti-rollover does not work effectively when driving at high speeds. On the other hand, if the threshold value is set based on high-speed driving, the suspension will be switched to a hard position every time even a small rollover that is not noticeable at low speeds will lead to the evaluation that the rollback prevention is working too hard. The suspension control device of the present invention solves the above problems,
The purpose is to prevent vehicle tailwinds that are appropriate for the driving conditions. ■ Town Structure The structure of the present invention that achieves the above object will be explained below. [Means for Solving the Problems] A suspension control device according to the present invention is illustrated in FIG. In a suspension control device that includes a vibration state detection means M1 that detects the state of vibration generated in a vehicle due to a change in the road surface, and changes the damping force characteristics of a shock absorber M2 based on the vibration state detection signal to suppress vehicle body vibration. , a sprung resonance component extraction means M3 for extracting a frequency component near the sprung resonance frequency from the vibration state detection signal; a vehicle speed detection means M4 for detecting the vehicle speed of the vehicle; Tolerance calculation means M5 for calculating an allowable range of the magnitude of the sprung mass resonance component; If the extracted sprung mass resonance component deviates from the calculated tolerance range 1: Increase the degree of damping force of the shock absorber M2; and a high damping force maintaining means M6 that maintains the damping force. [Function] In the suspension control device of the present invention having the above configuration, the vibration state detection signal of the vibration state detection means M1 that detects the state of vibration generated in the vehicle due to changes in the road surface (for example, the vehicle height detection signal that detects a change in vehicle height) A frequency component near the sprung mass resonance frequency is extracted by the sprung mass resonance component extracting means M3 from the signal or a damping force detection signal that detects the damping force generated by the shock absorber M2 when the vehicle height changes. The extracted sprung mass resonance component is j. This is a signal that can be used to determine the occurrence of vehicle tilting, which is a large change in vehicle height near the sprung mass resonance frequency. In this way, while extracting the sprung mass resonance component, the vehicle speed detection means M4 detects the vehicle speed, and according to this vehicle speed, the tolerance range calculation means M5 (3) calculates the tolerance range of the magnitude of the extracted sprung mass resonance component. . High damping force maintaining means M5 (t, when the extracted sprung mass resonance component signal is out of the tolerance range calculated based on the vehicle speed 1:
, the damping force generated by the shock absorber is maintained at a high level to prevent tilting. [Example]'' In order to clarify the structure and operation of the present invention explained above, a preferred embodiment of the suspension control device of the present invention will be described below. Fig. 2 shows the entire suspension control device 1. Fig. 3(A) is a partially broken sectional view of the shock absorber, and Fig. 3(B) is an enlarged sectional view of the main part of the shock absorber. As shown in 1-.Suspension control device 1 of this embodiment (shock absorber capable of changing damping force in two stages (hereinafter simply referred to as shock absorber) 2FL
, 2FR, 2RL, and 2RR, and an electronic control device 4 that is connected to each of these shock absorbers and controls their damping force. Each shock absorber 2
FL, 2FR, 2RL, 2RR are the suspension lower arms 6FL, 6FR, 6RL of the left and right front and rear wheels 5FL, 5FR, 5RL, and 5RR, respectively.
Coil spring 8FL is installed between 6RR and vehicle body 7.
, 8FR. It is attached to 8RL and 8RR. Shock absorber 2FL, 2FR, 2RL,
2RR (as mentioned above, shock absorber 2FL
, 2FR. A piezo load sensor that detects the force acting on 2R1 and 2RR, and shock absorbers 2FL, 2FR, and 2RL.
. Each of the 2RRs has a built-in piezo actuator that switches the setting of the damping force generation pattern for each stroke. Next, each of the above-mentioned shock absorbers 2FL and 2FR. The structure of 2-RL and 2RR will be explained, but each of the above shock absorbers 2FL, 2FR, 2RL, 2R
Since the structure of R is all the same, here we will use the left rear wheel SFL.
This will be explained by taking the side shock absorber 2FL as an example. In addition, in the following explanation, the codes of each member provided on each wheel in Table 1 are as necessary.
. Subscript FL corresponding to left rear wheel 5RL, right rear wheel 5RR,
F.R. R1 and RR shall be added, and if there is no difference regarding each wheel, the subscripts shall be omitted. Shock absorber 2 (upper) As shown in FIG. 3(A), the lower end of the cylinder 11 side is fixed to the suspension lower arm 6 (FIG. 2) via the axle side member 11a.
On the other hand, at the upper end of the rod 13 inserted into the cylinder 11,
It is fixed together with a coil spring 8 to the vehicle body 7 via a bearing 7a and a vibration isolating rubber 7b. Disposed inside the cylinder 11 are an internal cylinder 15 connected to the lower end of the rod 13, a connecting member 16, a cylindrical member 17, and a main piston 18 that is slidable along the inner peripheral surface of the cylinder 11. . An internal cylinder 15 connected to the rod 13 of the shock absorber 2 houses a piezo load sensor 25 and a piezo actuator 27 . The main piston 18 is fitted onto the upper cylindrical member 17, and a sealing material 19 is interposed on the outer periphery of the main piston 18, which fits into the cylinder 11. Therefore, the inside of the cylinder 11 is divided into a first liquid chamber 21 and a second liquid chamber 23 by the main piston 18 . As shown in FIG. 3(B), a backup member 28 is screwed to the tip of the cylindrical member 17.
The spacer 29 and leaf valve 30 are pressed and fixed on the cylindrical member 17 side, and the leaf valve 31 and collar 32 are pressed and fixed on the back-up member 28 side. Further, a main valve 34 and a spring 35 are interposed between the leaf valve 31 and the backup member 28, and urge the leaf valve 31 in the direction of the main piston 18. , main piston 18
When the main piston 18 is stopped, both the expansion and contraction passages 18a and 18b provided in the main piston 18 are closed on one side, and the main piston 1
8 opens to one side as it moves in the direction of arrow A or B. Therefore, the hydraulic oil (
As the main piston 18 moves, both passages 18.
a, 18b, and moves between the two liquid chambers 21, 23. In this way, the movement of hydraulic oil between the two liquid chambers 21 and 23 is limited to both passages 18a and 18b (
The damping force generated against the movement of the rod 13 is large, and the suspension characteristics become hard. A piezo load sensor 2 is housed inside the internal cylinder 15.
5 and the piezo actuator 27 are shown in FIG. 3(A),
As shown in (B), this is an electrostrictive element laminate in which thin plates of piezoelectric ceramics are stacked with electrodes in between. Each electrostrictive element of the piezo load sensor 25 is polarized by the force acting on the shock absorber 2, that is, the damping force. Therefore, the output of the piezo load sensor 25 can be extracted as a voltage signal by a circuit with a predetermined impedance (the rate of change in the damping force can be detected). The strain element is stacked to increase the amount of expansion and contraction, and directly drives the piston 36. When the piston 36 is moved in the direction of arrow B in FIG. 3(B), the hydraulic oil in the oil-tight chamber 33 via plunger 37 and H
The spool 41, which has a letter-shaped cross section, is also moved in the same direction. When the spool 41 in the position shown in FIG. 3(B) (origin position) moves in the direction B in the figure, the first liquid chamber 2
The sub-channel 16c connected to the pump 1 and the sub-channel 39b of the push 39 connected to the second liquid chamber 23 are communicated with each other. This sub-flow path 39b [flow path 17a in the cylindrical member 17 via the oil hole 45a provided in the plate valve 45]
Since these are in communication with each other, when the spool 41 moves in the direction of arrow B, result 1: the flow rate of hydraulic oil flowing between the first liquid chamber 21 and the second liquid chamber 23 increases. In other words,
Shock absorber 2 (Yo Piezo actuator 2)
When 7 expands due to the application of high voltage, its damping force characteristics are switched from high damping force (hard) to low damping force (soft), and when the charge is discharged and contracts, the damping force characteristics change to high damping force (hard). to return to the state of Note that the amount of movement of the leaf valve 31 provided on the lower surface of the main piston 18 (the amount of movement of the leaf valve 31
It is regulated compared to 0. In the plate valve 45, an oil hole 45b having a larger diameter than the oil hole 45a is provided outside the oil hole 45a, and the plate valve 45 is connected to the spring 4.
When the hydraulic oil moves in the direction of push 39 against the urging force of 6, it becomes movable through the upper oil hole 45b.
Regardless of the position of the spool 41, the main piston 1
The hydraulic fluid flow rate 1 when the main piston 18 moves in the direction of the arrow B is larger than that when the main piston 18 moves in the direction of the arrow 8. That is, the damping force is changed depending on the direction of movement of the main piston 18 (extension side and contraction side), thereby improving the characteristics as a shock absorber. A hydraulic oil supply path 3 is provided between the Mashidomari closed chamber 33 and the first liquid chamber 21.
8 is provided together with the check valve 38a, and the oil-tight chamber 3
The hydraulic oil flow rate in 3 is kept constant. Next 1: Regarding the electronic control device 4 that switches and controls the damping force generation pattern of the shock absorber 2 described above, the fourth
This will be explained using figures. This electronic control device 4 includes a piezo load sensor 25 of each shock absorber 2 (not shown), a steering sensor 50 that detects the steering angle of the steering wheel (not shown), and a steering sensor 50 that detects the steering angle of the steering wheel (not shown) as a sensor for detecting the running state of the vehicle. A vehicle speed sensor 51 that detects the shift position of a transmission (not shown), a shift position sensor 52 that detects the shift position of a transmission (not shown), and a stop lamp switch 53 that issues a signal when a brake pedal (not shown) is depressed are connected. An electronic control device 4m that outputs a control signal to the piezo actuator 27 described above based on a signal etc.
The PU 4a, ROM 4b, and RAM 4c are configured as an arithmetic and logic circuit, and input/output is performed with the outside through an input section 4e and an output section 4f, which are connected to each other via a common bus 4d. 1 to electronic control device 4 In addition, piezo load sensor 25
The damping force detection circuit 54 connected to the damping force detection circuit 54
A low-pass filter 55 and a bypass filter 56 as a band-pass filter are connected to the waveform shaping circuit 57 to which the steering sensor 50 and vehicle speed sensor 51 are connected, a high voltage application circuit 58 connected to the piezo actuator 27, and an ignition switch 63. A so-called switching regulator-type high voltage power supply circuit 62 receives power supply from the battery 61 and outputs a drive voltage for driving the piezo actuator, and converts the voltage of the battery 61 to the operating voltage (5V) of the electronic control unit 4. A constant voltage power supply circuit 64 and the like that generate the voltage are provided. Of the above configuration, the damping force detection circuit 54, bypass filter 56, waveform shaping circuit 57, shift position sensor 52, and stop lamp switch 53 are input to the input section 4e, while the high voltage application circuit 58 and high voltage power supply circuit 62 are output 4f. The damping force detection circuit 54 includes each piezo load sensor 25FL,
It consists of four detection circuits provided corresponding to 25FR, 25RL, and 25RR, and each detection circuit detects the voltage output from the circuit including the piezo load sensor 25 according to the acting force that the shock absorber 2 receives from the road surface. The signal is output to the CPU 4a as a damping force change rate detection signal, and a signal obtained by integrating this voltage signal is output to the CPU 4a and the low-pass filter 55 as a damping force detection signal. The components that have passed through the low-pass filter 55 as a band-pass filter and the bypass filter 56 are output to the CPU 4a. Of the damping force detection signals output by the damping force detection circuit 54, only one is output to the low-pass filter 55 [in the embodiment, the shock absorbers 2 of the left and right rear wheels 5RL and 5RH
This is the damping force detection signal of RL and 2RR. The low-pass filter 55 of the embodiment has a frequency of approximately 1°3[8z
, ] passes signals with the following frequencies. on the other hand,
The bypass filter 56 passes signals having a frequency of about 1°10 [Hz1 or more]. Therefore, when the damping force detection signal output from the damping force detection circuit 54 passes through the low-pass filter 55 and the bypass filter 56, among the components of the damping force detection signal, the frequency 1-0 [Hz1
A sprung mass resonance component signal, which is a signal with a frequency near the sprung mass resonance frequency, having a frequency of 1-3 [Hz] or less is extracted. An example of the sprung resonance component signal obtained in this way is
Shown in the graph of figure. The CPU 4a of the electronic control device 4 receives the various detection signals described above, such as the damping force change rate detection signal and the damping force detection signal output from the damping force detection circuit 54, and the low-pass filter 5.
5 and a bypass filter 56, a detection signal from the vehicle speed sensor 51, etc., into a signal suitable for processing in the CPU 4a, and an output signal from a waveform shaping circuit 57, which outputs the resultant signal suitable for processing by the CPU 4a, and further processing by itself. Based on the results, etc., it is possible to determine road surface conditions, vehicle driving conditions, etc. Based on this determination, the CPU 4a outputs a control signal to the high voltage application circuit 58 provided corresponding to each wheel. The high voltage application circuit 58 applies a voltage of +500 volts or -100 volts output from the high voltage power supply circuit 62.
This circuit applies voltage to the piezo actuator 27 in response to a control signal from the CPU 4a. Therefore, this damping force switching signal 1 causes the piezo actuator 27 to extend (
(when +500 volts are applied) or contract (when -100 volts is applied), the hydraulic oil flow rate is switched, and the damping force characteristic of the shock absorber 2 is switched to soft or hard. That is, the damping force characteristics of each shock absorber 2 (when the piezo actuator 27 is extended by applying a high voltage), the damping force characteristics of the spool 41 (Fig. 3 (B
)), the first liquid chamber 21 in the shock absorber 2
Since the flow rate of the hydraulic oil flowing between the liquid chamber 23 and the second liquid chamber 23 increases, the damping force becomes small, and when the piezo actuator 27 is contracted by discharging the electric charge due to the negative voltage, the C-type hydraulic oil Since the flow rate decreases, the damping force becomes large. Next 1: The damping force control performed by the electronic control device 4 of the suspension control device 1 of this embodiment having the above-described configuration will be explained based on the flowchart of FIG. 7. Each routine E shown in each figure is repeatedly executed by interrupt processing at predetermined fixed time intervals. The processing contents of each routine are as follows. ■Damping force control routine (Fig. 6) Damping force control is normally performed to change the setting of the damping force generation pattern of the shock absorber 2 to be high or low depending on the road surface condition. When the start conditions for anti-rolling are met, the settings of the shock absorbers 2 on all four wheels are switched to a high damping force generation pattern, giving priority to the normal damping force control based on the road surface condition, and the suspension is made harder. Execute anti-slip prevention measures. In addition, when the end condition for anti-swinging is met, the execution of anti-swinging that hardens the suspension is terminated. ■ Anti-tilt interrupt routine (FIG. 7) A sign of the occurrence of tailgating is detected, and it is determined based on the vehicle speed whether the start condition for executing the tailgating prevention is satisfied. Furthermore, while the tilt prevention is being executed, it is determined whether a condition for ending the tilt prevention execution is satisfied. In addition, in the embodiment, the anti-tilt interrupt routine (Fig. 7) applies to the shock absorbers 2R of the left and right rear wheels 5RL and 5RR.
This is done independently for L and 2RR. The details of each routine will be explained below, starting with the damping force control routine (FIG. 6). When the damping force control routine is started, first, a judgment process (
Step 100) is performed. Hardware priority switching flag HF
(t, when the start condition for the tilt prevention execution is satisfied in the tilt prevention interrupt routine (FIG. 7) 1:, this is a flag that is set to the value 1 in the process of step 130, which will be described later. The hardware priority switching flag HF is If the value is not set to 1 and rYESJ is determined in step 100, then C
Normal damping force control processing based on road surface conditions (step 11)
0). Overview of damping force control processing (above various sensors b)
The driving condition (steering angle, vehicle speed, etc.) is determined based on the detection signals of % and 1:. The road surface condition is determined based on the damping force change rate detection signal and the damping force detection signal from the damping force detection circuit 54, and depending on the results of these determinations, the high and low settings of the damping force generation pattern of the shock absorber 2 are switched, and the suspension This means making it soft or hard. Generally speaking, if the road is in bad condition, go softer, and if the road is flat, go harder. After the damping force control process (step 110), every time this routine is repeated, the left and right wheels 5R[. Anti-tilt interrupt routine performed independently for 5RR (
7), each tilt prevention start flag SFR
, SFL is set to the value 1 (step 120), and the tilt prevention start flag SFR,SFL(,t) In each tilt prevention interrupt routine, the start condition for the tilt prevention execution is determined. If it is true, it is set to the value 1. If it is determined that one of the above flags is also set, IL performs the process (step 130) of setting the above-mentioned hardware priority switching flag HF to the value 1, and then starts this routine. The process ends once. In response to the above processing, if the hardware priority switching flag HF is set to the value 1 in step 100 and it is determined that rNOl (Friend's tailgating prevention execution processing (step 140)
Do this. In the anti-rolling execution process, the shock absorbers 2 of all four wheels are set to a high damping force generation pattern, giving priority to the results of the normal damping force control process (step 110) based on the above-mentioned road surface conditions. , if the suspension is soft, it switches to hard, and if it is hard, it remains hard. After the tilt prevention execution process (step 140) (every time the above routine is repeated 1:, left and right wheels 5 RL. 5 RRI: In the tilt prevention interrupt routine that is performed independently, both end flags EFR and EFL are set to 1).
A judgment process (step 150) is performed to determine whether or not it has been set. Both exit flags EFR. When it is determined that EFL is set to the value 1, it is determined that the possibility of occurrence of C-top tilting has been eliminated, and the above-mentioned hardware priority switching flag HF is reset to the value 0 (step 1).
60), and this process is temporarily ended. When the hard priority switching flag HF is reset to the value 0 in this way, in the next execution of the routine (upper step 110), normal damping force control processing based on the road surface condition is performed, and if the road surface condition is bad, the suspension is softened, If the road surface condition is flat, control such as hardening is realized.Next 1: Start flags SFR, SFL and end flag EF of anti-rolling are referenced in this damping force control routine.
The anti-tilt interrupt routine that determines R and EFL is performed in the seventh
This will be explained based on the flowcharts in FIGS. (A) and (B). In addition, the anti-tilt interrupt routine is for the left and right wheels 5RL.
, 5RRI: These are performed independently, but the processing for each wheel is the same, so the explanation will be made without making any particular distinction. When this interrupt routine is started, as shown in FIG. 7(A), step 1: First, a process (step 200). Next 1: It is determined whether the hardware priority switching flag HF is set to the value 1 (step 210). The hardware priority switching flag HF is not set to the value 1,
If it is determined as [NO], the processing for determining the start condition for the tilt prevention execution shown in steps 220 onwards is executed.Meanwhile, in step 210, the hardware priority switching flag HF is set.
is set to the value 1, and if it is determined that LL is rYEsJ, the process moves to the process of determining the termination condition for the tilt prevention execution shown in FIG. 7(B). Outline 1 of the start condition determination process shown in FIG. 7(A) The damping force data P and vehicle speed data S updated in step 200 are monitored, and the damping force data P is calculated based on the vehicle speed data S. If the threshold value is outside the range 1: it is determined that the conditions for starting the tilt prevention execution are satisfied, and the tilt prevention start flag SF is set. 1 in the start condition determination process. First, it is determined whether the setting of the damping force generation pattern of the shock absorber 2 is low damping force or high damping force (Step 220), and according to the determined setting,
Processing for calculating threshold values +SLI and -SL2 from vehicle speed data S (steps 230 and 240) is performed. In the example, the threshold value +SLl, -SL2 (see Fig. 5)
For each setting of the shock absorber 2, the functions fl (SP), gl (SP), f2 (SP), g2 of the vehicle speed data SP are
(SP). Figure 8 shows the threshold +S
The relationship between L1, -SL2 and vehicle speed data SP will be illustrated. The vertical axis is the absolute threshold value +SLI, -SL2 (li
t The horizontal axis indicates the magnitude of vehicle speed data SP. As shown in the figure 1: Threshold value +SLI, -SL of the embodiment
2[1 The absolute value is set to become smaller as the vehicle speed data SP becomes larger. In addition, the threshold value + for the extension side of the shock absorber 2
The absolute value of SLI is set to a value relatively larger than the absolute value of 1 and the absolute value of the threshold value for the contraction side - SL2. This is to compensate for the fact that the absolute value of the damping force on the extension side is relatively larger than the absolute value of the damping force on the contraction side. Also, the function f2(SP). The absolute value of the threshold value for high damping force calculated by g2 (S P) is relative to the absolute value of the threshold value for low damping force calculated by the function function fl(SP), gl(SP). It is destined to grow bigger. This is to compensate for the fact that, even on the same road surface, the level of damping force generated while the vehicle is running is higher when the damping force is set to a high damping force than when the damping force is set to a low damping force. In this way, when the threshold values +SLI and -SL2 are calculated from the vehicle speed data sp according to the settings of the shock absorber 2,
Next, a process (step 250) is performed to determine whether the damping force data P read in step 200 is outside the range of threshold values +SLI and -SL2. In step 250, the damping force data P is equal to or greater than the threshold value
It is within the range of SLI, -SL2, "NO"
If it is determined that there is no sign of occurrence of excessive tilting (step 260), the counter Cst for measuring the determination period ΔTst of the start condition to be described later is cleared (step 260), and the tilt prevention start flag SF is reset (step 270). , this process is temporarily terminated. On the other hand, in step 250, the damping force data P is outside the range of threshold +SLI, -SL2, and rY
If it is determined that ESJ has occurred, it is determined that there is a possibility that a sign of tilt occurrence has been detected, and the next step 1: Increment the counter Cstt for timing the determination period ΔTs of the start condition (step 280), and increment the incremented counter Cs.
Whether t is greater than or equal to the judgment value Vs, that is, the increment of the counter CsL is repeated to complete the measurement of the judgment period ΔTs, and during the judgment period ΔTs, the damping force data P continues to be the threshold value +SLI, -SL2. A process (step 290) is performed to determine whether or not the range has been exceeded. For example, in an example where the suspension shown in the graph in Figure 5 is initially set to soft, the damping force continues to exceed the threshold value SL1 after time t1, and the anti-rolling control is executed after time t1. In the embedding routine, each time the process is repeated,
:, damping force data P is threshold value +SL in step 250.
Judgment is 1 or more consecutively. Therefore, the counter Cst is not reset and is incremented one after another in step 280 until it reaches the card determination value Vs. As a result, the determination period ΔTs expires at time t2, and during the determination period ΔTs, the damping force data P continuously changes to the threshold value +SLI, -SL.
It can be confirmed that it is out of the range of 2. As in this example, the counter Cst increases and step 2
If it is determined that the damping force is greater than or equal to the judgment value Vs in step 90, that is, if the damping force continues to be out of the threshold range for the judgment period ΔTs (t,), it is determined that a sign of the occurrence of tilting has been detected, and the tilting prevention start flag is set. The process of setting SF to the value 1 (step 300) is executed. On the other hand, if it is determined that the counter Cst is less than or equal to the judgment value Vs, it is determined that no sign of the occurrence of drift has been detected, and this process is temporarily terminated. When the anti-rolling prevention start flag SF is set to the value 1 in step 300, the damping force control routine (sixth
Figure) At N:, the hard priority switching plug HF is set to the value 1 (step 130), and the anti-tilt execution process (step 140) switches the damping force setting of all four wheels of the shock absorber 2 to high damping force. executed. According to the start condition determination processing described above, the following control for preventing tilting is realized. Threshold value for determining the magnitude of damping force data P + SLI,
-The range of SL2 narrows as the vehicle speed increases, so even if the suspension is small and does not perform anti-slip suspension when driving at low speeds, it will perform anti-slip suspension when driving at high speeds, and if the suspension is soft, it will switch to hard suspension, and if it is hard, it will perform anti-slip suspension. Keep it hard. On the other hand, when driving at low speeds, the range of threshold values +SL1 and -SL2 [is wider than when driving at high speeds, so do not perform tilt prevention for small tilts that do not bother you. The damping force data P determines the range of threshold value +SLI, -SL2 during the judgment period Δ
This is to compensate for the characteristics of the low-pass filter 55, for example, in addition to the requirement for detecting a sign of the occurrence of overturning, which continues to be off during Ts. Low-pass filter 55 [Friend] Some of the high-frequency components unrelated to the soil agitation are passed through, but these high-frequency components are at the threshold +SLI, -SL
Even if it exceeds 2, it will stop immediately. The damping force data P continues to be the threshold value +SLI during the determination period ΔTs. -By making it a requirement that the suspension be out of the SL2 range (the risk of misjudgment due to high frequency components that quickly fall off is removed), the decision period ΔTs is provided to slightly delay the timing of switching the suspension to hard. This is to intuitively optimize the timing.As in the device of this embodiment, there are two types of suspension stiffness: soft and hard.
This is because if the driver detects a sign of the vehicle's steering and switches from soft to hard before it occurs, the driver may not understand why it has changed to hard, and this may create a sense of discomfort. Note that the determination period ΔTs for this purpose is a minute time compared to the period of the vehicle's tilting. Next 1: The termination condition determination process shown in FIG. 7(B) will be explained. Judgment process for end conditions in the embodiment
This is to set the tilt prevention end flag EF. In this judgment process, first, the damping force data P is the threshold value + SL3. - Execute the judgment process (step 310) as to whether or not it falls within the range of SL4 (see FIG. 5). If the damping force data P is out of the range of the threshold values +S13 and -SL4 and rNOJ is determined in step 310. Counter Cedf for measuring the end condition determination period ΔTe: Clear step 320
), the process of resetting the tilt prevention end flag EF (step 330) is performed, and this process is temporarily ended. On the other hand, the damping force data P is the threshold value +SL3. - If it is within the range of SL4 and rYESJ is determined in step 310 (if the companion damping force is small (for example, from time t3 to time t5 in FIG. 5), there is a possibility that the termination condition is satisfied. Step 3
40), the incremented counter Ced is the judgment value V
A process (step 350) is performed to determine whether or not it is less than or equal to s, that is, whether or not the end determination period ΔTe has been counted by incrementing the counter Ced. Counter Ced (Table) Every time the tilt prevention interrupt routine is repeated, the damping force data P increases to the threshold value + SL3° - SL4
(step 310), increment one after another (step 310).
Step 340) Increase to the judgment value Ve. For example, since the damping force data P is within the threshold value in the processing performed after time t3 shown in Fig. 5,
The counter Ced continuously increases, but since the damping force data P goes out of that range at time t4, it is reset (step 320) and does not increase to the determination value Ve. In such a case, it is determined that the friend counter Ced is less than the judgment value Ve (step 350), and it is determined that there is a risk of a tilt occurring if the tilt prevention execution has ended, and the end flag EF is reset (step 330). After execution, the process is temporarily terminated. In the damping force control routine (FIG. 6), the tilt prevention execution process (step 140) is executed. On the other hand, in the process performed after time t5 shown in FIG.
Since it continues to fall within the range of , the counter Ced
increases to the judgment value Ve. Therefore, at time t6 when the counter Ced increases to the judgment value Ve, the counter Ced
is determined to be greater than or equal to the judgment value Ve (step 350), and it is determined that there is no risk of occurrence of tilt even if the tilt prevention is completed, and an end flag EF is set (step 360).
). In the anti-tilt interrupt routine that is performed independently for the left and right rear wheels 5RL and 5RR as described above,
When the prevention end flag EF of both routines is set, the hard priority switching flag HF is reset (step 16) in the damping force control routine (Fig. 6) as described above.
0) to be done. Thereafter, in the damping force control routine (step 110), the damping force control process based on the normal road surface condition is performed, and if the road surface condition is bad, the suspension is made soft, and if the road surface is flat, the suspension is made hard. In the example, the suspension is softened by the expiration of the termination condition determination period ΔTe at time t6. Note that if the termination condition determination period ΔTe(t and the damping force data P are within the range of the threshold value +SL3.−SL4) It is set to a period longer than the period of vibration near the sprung resonance frequency.In addition, the determination period ΔT
e stipulates the minimum execution period for prevention of agitation,
It is set to a period in which the effect of preventing turbulence can be effectively obtained. As explained above, according to the suspension control device of the embodiment, as the vehicle speed data SP becomes larger, the range of the starting condition thresholds +SLI and -SL2 is narrowed.
As the vehicle speed increases, even a small tilt can be prevented, and the excellent effect of properly preventing tilt is achieved. Therefore, when driving at high speeds, even small tails that are not noticeable when driving at low speeds can be prevented from rolling at high speeds.On the other hand, when driving at low speeds, there is an excellent system that prevents the suspension from becoming unnecessarily hard. Riding comfort can be ensured. Further, in the embodiment, the threshold values +SLI and -SL2 are set to the numerical aperture fl (SP) of the vehicle speed data SP, depending on the difference in the height setting of the damping force generation pattern of the shock absorber 2.
gl (SP), f2 (SP), g2 (sp)
Therefore, it is possible to determine the anti-tilt start condition that compensates for the difference in the settings of the shock absorber 2. In addition, since the suspension control device of the embodiment makes the judgment based on the damping force detection signal, it is possible to detect a sign of the occurrence of tilting, and it is possible to prevent tilting. 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. For example, 1'K Relationship between vehicle speed and the range of threshold values +SLI and -SL2 used in the starting conditions for anti-rollover c Table In addition to the configuration in which the vehicle speed narrows linearly as the vehicle speed increases as in the example, there are also experiments. ,
Please set various relationships that are more suitable for actual driving conditions.
X. In addition, a configuration 1 in which the threshold values +SLI and -SL2 are determined according to the vehicle speed, and a configuration in which the determination period ΔTs of the start condition is determined according to the vehicle speed, for example, a configuration in which the determination period ΔTs is shortened as the vehicle speed increases. You can also add L ~ This makes it possible to prevent tilting that is more suited to the vehicle speed. Also, in the end condition determination process (for example, as the vehicle speed increases, the range of threshold +SL3.-SL4 It is also possible to use a configuration in which the determination period ΔTe is narrowed or the determination period ΔTe is lengthened. This configuration allows compensation for the minimum period of the anti-rolling prevention execution period when the vehicle speed changes, and compensation for the minimum period of execution of the anti-rolling prevention execution period depending on the vehicle speed. This makes it possible to make changes to the anti-rolling effect that is best suited to the driving conditions.The L-rolling prevention interrupt routine is performed not only for the left and right rear wheels, but also for any two of the four wheels. You can do this on any three wheels or all four wheels. You can do it on any one of the four wheels.
In this case, the processing performed by the electronic control device 4 can be simplified. The damping force generation pattern of the shock absorber 2 may be set in three or more stages. It may be possible to set it steplessly. In the embodiment, 1, the threshold value of the termination condition + SL3. - The absolute value of SL4 is the threshold value of the starting condition + SLI. - h(,
There are various possible relationships between the two values, such as the former being the same as the latter depending on the vibration characteristics of the vehicle. Effects of the Invention As detailed above, the suspension control device of the present invention extracts the sprung mass resonance component from the vibration state detection signal that detects the state of vibration generated in the vehicle, and extracts the sprung mass resonance component. If the magnitude of the vehicle is out of the allowable range determined according to the vehicle speed, the vehicle will perform tilt prevention, so the magnitude of the vehicle tilt that prevents vehicle tilt can be changed according to the vehicle speed.
This provides an excellent effect in that tilting can be suitably prevented depending on the driving condition.

[Brief explanation of the drawing]

FIG. 1 is a block diagram illustrating the basic configuration of the present invention, and FIG. 2 is a schematic configuration diagram showing the overall configuration of a suspension control device as an embodiment of the present invention. FIG. 3(A) is a partial sectional view showing the structure of the shock absorber, FIG. 3(B) is an enlarged sectional view of the main parts of the shock absorber, and FIG. 4 is a block diagram showing the configuration of the electronic control device of this embodiment. 5 is a graph showing an example of the damping force detection signal that has passed through the low-pass filter 55 and the bypass filter 56, FIG. 6 is a flowchart showing the damping force control routine, and FIG. 7 is a flowchart showing the tilt prevention interrupt routine. , FIG. 8 is a graph illustrating the relationship between threshold value and vehicle speed. 2F1.2FR, 2RL, 2RR - Damping force variable shock absorber 4 - Electronic control unit 25FL, 25F town 25RL, 25RR - Piezo load sensor 27FL, -27FR, 27RL, 27RR -
... Piezo actuator 54 ... - Damping force detection circuit 55 - Pass filter 56 - High pass filter 58 - High voltage application circuit 62 - High voltage power supply circuit

Claims (1)

[Claims] 1. A vibration state detection means for detecting the state of vibration generated in the vehicle due to changes in the road surface, and based on the vibration state detection signal, damping force characteristics of the shock absorber are changed to suppress vehicle body vibration. A suspension control device comprising: a sprung mass resonance component extraction means for extracting a frequency component near the sprung mass resonance frequency from the vibration state detection signal; a vehicle speed detection means for detecting the vehicle speed of the vehicle; Tolerance calculation means for calculating an allowable range of the magnitude of the extracted sprung mass resonance component, and increasing the degree of damping force of the shock absorber when the extracted sprung mass resonance component deviates from the calculated tolerance range. A suspension control device comprising: means for maintaining a high damping force;