JPH03182828A - Suspension control device - Google Patents

Abstract

PURPOSE:To always control damping force optimumly in response to the road surface condition by setting the holding time of the damping force of a shock absorber between a switch from large to small and a reset in response to the road surface condition to be reflected in a damping force change ratio. CONSTITUTION:Damping force of a shock absorber M1 provided in a suspension S of a vehicle is controlled by a means M3 on the basis of the relation of size between a damping force change ratio detected by a means M2 and a preset reference value for adjusting the damping force. In a device described before, when a damping force change ratio is at a value except a first reference value, the damping force is switched by a means M4 so as to be changed from large to small in the described means M3. After changing the damping force to small, when a damping force change ratio is continued more than the predetermined time within a second reference value of which absolute value is smaller than the first reference value, the damping force is reset by a means M5 so as to be changed from small to large.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a suspension control device, and more specifically, the present invention relates to a suspension control device, and more specifically, the present invention relates to a suspension control device that is equipped with a shock absorber that can vary the setting of damping force, and that adjusts the damping force based on the driving condition of the vehicle. The present invention relates to a suspension control device that controls the generation pattern of damping force of a shock absorber.

[Prior Art] This type of suspension control device detects the rate of change in the damping force of a shock absorber, and when this rate of change exceeds a predetermined value, that is, the damping force is increased based on unevenness of the road surface, brake operation, etc. There are known devices that quickly switch the generation pattern of the damping force against the movement of the shock absorber to a smaller value when a sudden change occurs (for example, Japanese Patent Laid-Open No. 6
4. -67407 Publication) 9 The rate of change of damping force is responsiveness 1
Because of this excellent signal, these suspension control systems can quickly follow changes in the damping force pattern to changes in road surface conditions to maintain good ride comfort.

[Problems to be Solved by the Invention] The suspension control device that uses the rate of change in damping force has excellent responsiveness, but when driving on rough roads, the rate of change signal is not the standard for adjustment. If the damping force goes up or down in a short period of time, there is no point in controlling the damping force if the damping force setting is changed according to the magnitude relationship with respect to the adjustment reference value. If the value is exceeded, it becomes necessary to maintain the damping force setting for a predetermined period of time. However, after switching the damping force setting, simply continuing that state for a certain period of time does not adequately respond to the road surface condition. When driving, the rate of change in damping force fluctuates rapidly, so if the damping force generation pattern is maintained in a soft pattern for a short period of time, the frequency of damping force changes will increase, creating a sense of discomfort. This also has a negative impact on the durability of the shock absorber. On the other hand, if the period of keeping the damping force soft is too long, when driving on a relatively flat road surface, the damping force setting will be kept soft for an unnecessarily long time after passing over a small bump, etc. It invites the problem of loss of sexuality. As a result, the driving feeling may deteriorate.

The suspension control device of the present invention solves the above problems,
The purpose of this invention is to control the setting of damping force using the damping force change rate in accordance with road surface conditions.

Configuration of the Invention The configuration of the present invention that achieves the above object will be described below.

[Means for Solving the Problems] As illustrated in FIG. 1, the suspension control device of the present invention comprises: a shock absorber M1 that is provided in a suspension S of a vehicle and is capable of setting a damping force generation pattern; Based on the damping force change rate detection means M2 that detects the change rate of the damping force of the absorber M1, and the magnitude relationship between the detected damping force change rate and the damping force adjustment reference value,
In the suspension control device, the damping force control means M3 changes the setting of the damping force of the shock absorber M1, and the damping force control means M3 controls the rate of change of the damping force outside the range of the first reference value S1. a damping force switching means M4 that changes the damping force setting of the shock absorber M1 from large to small when it is determined that the damping force setting is small; and after the damping force setting is changed to small by the damping force switching means M4, The rate of change of the damping force is equal to the first reference value S1
The damping force restoration means M5 changes the setting of the damping force from small to large when it is determined that the damping force has continued for a predetermined period or more within the range of the second reference value S2 having a smaller absolute value. shall be.

[Function] The suspension control device of the present invention having the above configuration has the following features:
The rate of change in the damping force of the shock absorber M1 provided in the suspension S of the vehicle is detected by the damping force change rate detection means M2, and based on the magnitude relationship between the rate of change in the damping force and a reference value for adjusting the damping force. , the setting of the damping force of the shock absorber M1 is changed by the damping force control means M3.

The setting of this damping force is first changed from large to small by the damping force switching means M4 when the rate of change of the damping force is outside the range of the first reference value S1. After this change, when the rate of change of the damping force continues within the range of the second reference value S2 for a predetermined time or more, the damping force setting is changed from small to large by the damping force restoration means M5.

That is, when the rate of change in the damping force falls outside the range of the first reference value S1, the setting of the damping force of the shock absorber M1 is switched from large to small, and thereafter this rate of change is set to the second reference value s2.
When the damping force remains within the range for a predetermined period of time, the damping force setting returns from small to large.

Therefore, in the suspension control device of the present invention, the holding period from when the damping force setting is switched from high to low until it returns is determined according to the road surface condition reflected in the state of the damping force change rate. .

Note that such control may be performed independently for each wheel, or may be performed commonly for the two front wheels and the two rear wheels, or may be performed commonly for all wheels.

[Examples] In order to further clarify the configuration and operation of the present invention described above, preferred embodiments of the suspension control device of the present invention will be described below.

FIG. 2 is a schematic configuration diagram showing the overall configuration of this suspension control device 1, FIG. 3(A) is a partially cutaway sectional view of the shock absorber, and FIG. FIG.

As shown in FIG. 2, the suspension control device 1 of this embodiment includes shock absorbers 2FL, 2FR, 2RL, and 2RR that can change the damping force in two stages, and a shock absorber connected to each of these shock absorbers to change the damping force. It is composed of an electronic control device 4 for controlling.

Each shock absorber 2FL, 2FR, 2RL,
2RR1 top, left and right front and rear wheels 5FL, 5FR, 5 respectively
RL, 5RR suspension lower arm 6FL
, between 6FR, 6RL, 6RR and the vehicle body 7,
Coil springs 8FL, 8FR.

Together with 8RL and 8RR (both are located side by side).

Shock absorber 2FL, 2FR, 2RL,
2RR [As described later (2. Shock absorber 2F)
L, 2FR.

A piezo load sensor that detects the force acting on 2RL and 2RR, and shock absorbers 2FL, 2FR, and 2
R.L.

Each set includes a piezo actuator that switches the setting of the damping force generation pattern in the 2RR.

Next, each of the above-mentioned shock absorbers 2FL and 2FR.

The structure of 2RL and 2RR will be explained, but each of the above shock absorbers 2FL, 2FR, 2RL, 2RR
Since all of the structures are the same, the shock absorber 2FL on the left front wheel 5FL side will be explained here as an example. In the following description, the reference numerals of each member provided on each wheel include front left wheel 5 FL and front right wheel 5 FR, as necessary.

Subscript FL corresponding to left rear wheel 5RL and right rear wheel 5RR
, F.R.

RL and RR shall be added, and if there is no difference regarding each wheel, the subscripts shall be omitted.

The shock absorber 2, as shown in FIG. 3(A),
The lower end of the cylinder 11 side is fixed to the suspension lower arm 6 via the axle side member 11a, while the upper end of the rod 13 inserted through the cylinder 11 is fixed to the vehicle body 7 via the bearing 7a and the vibration isolating rubber 7b. is fixed together with a coil spring 8.

Inside the cylinder 11 is 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 surface of the cylinder 1 are provided. 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 outside of the cylindrical member ] 7 , and a sealing material 19 is interposed on the outer periphery that 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. A backup member 28 is screwed onto the tip of the cylindrical member 17, and between the cylindrical member 17 and the main piston 18, a spacer 29 and a leaf valve 30 are placed on the cylindrical member 17 side, and a leaf valve 31 and a leaf valve 30 are placed on the cylindrical member 17 side. color 3
2 are pressed and fixed to the backup member 28 side, respectively. 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.

These leaf valves 30, 31 are connected to the main piston 18.
When the main piston 18 is stopped, the extension side and the contraction narrow passage 18a provided in the main piston 18.

18b are each 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, as the main piston ]8 moves, the hydraulic oil filled in both the liquid chambers 21 and 23 flows through both passages 18a and 23.
78b to move between the two liquid chambers 21, 23. In this state where 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 characteristics of the suspension 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),
(B)I As shown, 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, by extracting the output of the piezo load sensor 25 as a voltage signal using a circuit with a predetermined impedance, the rate of change in damping force can be detected.

The piezo actuator 27 is an electrostrictive element that expands and contracts with good response when a high voltage is applied, and the amount of expansion and contraction is increased by laminating layers 1-, and directly drives the piston 36. When the piston 36 is moved in the direction of arrow B in FIG. 3(B), the plunger 37 and the spool 41 having a mouth-shaped cross section are also moved in the same direction via the hydraulic oil in the oil-tight chamber 33. In this way, when the spool 41 at the position shown in FIG.
The sub-channel 39b of the bushing 39 connected to the bushing 39 is communicated with the bushing 39. This sub-flow path 39b is further communicated with the flow path 17a in the cylindrical member 7 through an oil filler 45a provided in the plate valve 45, so that when the spool 4 moves in the direction of arrow B, As a result, the flow rate of the hydraulic oil flowing between the first liquid chamber 21 and the second liquid chamber 23 increases. In other words, when the piezo actuator 27 is expanded by applying a high voltage, the shock absorber 2 changes its damping force characteristics from a state of high damping force (hard) to a state of low damping force (soft).
When the damping force characteristics are switched to the 2- side, the charge is discharged and contracted, and the damping force characteristics are returned to the state of high damping force (hard).

The amount of movement of the leaf valve 3 provided on the lower surface of the main piston 18 is determined by the spring 35.
It is regulated compared to In addition, the plate valve 45 has an oil filler 45b having a larger diameter than the oil filler 4.5a.
When the plate valve 45 moves toward the bush 39 against the urging force of the spring 46, the hydraulic oil can move through the oil filler 45b. Therefore, regardless of the position of the spool 41, the flow rate of hydraulic oil when the main piston 18 moves in the direction of arrow B is larger than when the main piston 8 moves in the direction of the arrow. That is, the damping force is changed depending on the moving direction of the main piston 18, thereby improving the characteristics as a shock absorber. Further, a hydraulic oil supply path 38 is provided between the oil-tight chamber 33 and the first liquid chamber 21, together with a check valve 38a, to keep the flow rate of the hydraulic oil in the oil-tight chamber 33 constant.

Next, the electronic control device 4 that switches and controls the generation pattern of the damping force of the shock absorber 2 described above will be explained using FIG. 4.

This electronic control device 4 includes a sensor for detecting the running state of the vehicle, a steering sensor 50 for detecting the steering angle of a steering wheel (not shown), and a piezo load sensor 25 (N) of each shock absorber 2; A vehicle speed sensor 5 that detects the running speed of the vehicle, a shift position sensor 52 that detects the shift position of a transmission (not shown), a stop lamp switch 53 that issues a signal when a brake pedal (not shown) is depressed, etc. are connected. ing.

The electronic control device 4 which outputs control signals to the piezo actuator 27 described above based on these detection signals etc. is a well-known CP device 61. ROM62. It is configured as an arithmetic and logic operation circuit centering around a RAM 64, and inputs and outputs to and from the outside through an input section 67 and an output section 68 that are mutually connected to these circuits via a common bus 65.

In addition, the electronic control device 4 includes a damping force change rate detection circuit 70 connected to the piezo load sensor 25, a waveform shaping circuit 73 connected to the steering sensor 50 and the vehicle speed sensor 51, and a high voltage connected to the piezo actuator 27. An application circuit 75 receives power from a battery 77 via an ignition switch 76, and a so-called switching regulator type high voltage power supply circuit 79 outputs a drive voltage for driving a piezo actuator, converting the voltage of the battery 77 and controlling it electronically. A constant voltage power supply circuit 80 that generates an operating voltage (5V) for the device 4 is provided. Shift position sensor 52. Stop lamp switch 53. Damping force change rate detection circuit 70. The waveform shaping circuit 73 has an input section 67,
On the other hand, high voltage application circuit 75. The high voltage power supply circuits 79 are connected to the output sections 68, respectively.

The damping force change rate detection circuit 70 is connected to each piezo load sensor 25.
It consists of four detection circuits provided corresponding to FL, FR, RL, and RR, and each detection circuit receives an output from a circuit including the piezo load sensor 25 according to the acting force that the shock absorber 2 receives from the road surface. I5- is configured to output the voltage signal V to the CPU 61 as the damping force change rate of the shock absorber 2. Further, the waveform shaping circuit 73 is a circuit that shapes the detection signals from the steering sensor 50 and the vehicle speed sensor 51 into a signal suitable for processing in the CPU 61 and outputs the waveform shaped signal. Therefore, the CPU 61 can determine the road surface condition, the running condition of the vehicle, etc. based on the output signals from the damping force change rate detection circuit 70 and the waveform shaping circuit 73, as well as its own processing results. Based on this determination, the CPU 61 outputs a control signal to the high voltage application circuit 75 provided corresponding to each wheel.

This high voltage application circuit 75 is a circuit that applies a voltage of +500 volts or 1100 volts output from the high voltage power supply circuit 79 to the piezo actuator 27 in accordance with a control signal from the CPU 61. Therefore, in response to this damping force switching signal, the piezo actuator 27 expands (when +500 volts is applied) or contracts (when -100 volts is applied), the hydraulic oil flow rate is switched, and the damping force characteristics of the shock absorber 6-saw μ2 are changed. Can be switched to soft or hard. That is, the damping force characteristic of each shock absorber 2 is such that when a high voltage is applied to extend the piezo actuator 27, the damping force characteristic of the spool 41 (see Fig. 3 (B
)), the first liquid chamber 2 in the shock absorber 2]
Since the flow rate of the hydraulic oil flowing between the second 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 with a negative voltage, the hydraulic oil flow rate decreases. This results in a state of large damping force. Note that once the electric charge accumulated in the piezo actuator 27 is discharged, the piezo actuator 27 remains in a contracted state even if the negative voltage is removed, and the shock absorber 2 maintains a state with a large damping force.

Next, the damping force control performed by the suspension control device 1 of this embodiment having the above-described configuration will be explained based on the flowchart of FIG. 5. This damping force control interrupt processing routine is repeatedly executed at regular intervals after flags FS, FA, etc., which will be described later, are reset to a value O in an initialization process (not shown) when the power is turned on. Note that these processes are performed on each shock absorber 2 FL of each wheel.
Although the processing is executed for each of the FR, RL, and RR, there is no difference in the processing for each wheel, so the explanation will be made without making any particular distinction.

When the processing routine shown in FIG. 5 is started, first, the rate of change V of the damping force of each shock absorber 2 is read from the damping force change rate detection circuit 70 via the input section 67 (step 100). It is determined whether the absolute value of this damping force change rate V (hereinafter simply referred to as damping force change rate V) is larger than the first reference value v1 (step 110).
). This first reference value v1 may be a predetermined value, or may be set in another routine (not shown) as a value according to the vehicle speed, or may be a value such as the switching frequency of the damping force setting of the shock absorber 2, etc. It may be learned based on.

FIG. 6 is a graph showing an example of the rate of change in damping force V. When the rate of change in damping force V is smaller than the first reference value v1 as before time t1 shown in the diagram, the suspension characteristics change to soft 1. The flag “S is set to 1” indicates that it is set to
It is determined whether or not (step 120), and the flag FS is
If the value is not 1, the suspension is controlled hard (step 130), and this routine is temporarily terminated.

In addition, in the process of step 130 for hard suspension control, immediately after the setting of the damping force of the shock absorber 2 is switched from soft to hard, 1100 volts is applied from the high voltage application circuit 75 by the control signal from the output section 68. is applied to the piezo actuator 27 to contract it, and if the piezo actuator 27 is already in a contracted state, it is held as it is.

On the other hand, if the damping force change rate V becomes larger than the first reference value V1, as shown at time t in FIG.
10), set the value 1 to the flag FS step 140
), then a high voltage of +500 volts is applied to the piezo actuator 27 from the high voltage application circuit 75 to switch and control the damping force of the shock absorber = 19-2 to a small state, that is, to softly control the suspension. (step 150), and this routine ends.

Eventually, as shown at time t2 in FIG. 6, the damping force change rate V
When the damping force change rate V becomes equal to or less than the first reference value v1, the judgment at step 110 becomes rNOJ, and after checking the flag FSO value (step 120), the damping force change rate V becomes the second reference value V.
2 (set to a value smaller than the first reference value) is determined (step 160). During the period from time t2 to time t3, this judgment is rNOJ, and the shock absorber The damping force setting of No. 2 is still maintained (softly maintained at step 150), and this routine ends.

When this process is repeated and time t3 has elapsed, the determination at step 160 becomes rYESJ, and the flag FA
It is determined whether the value of is 0 (step 180). Since this flag FA is set to the value 1 at =20- after V<V2, the value becomes 0 immediately after the damping force change rate V falls below the second reference value V2. Therefore, if it is determined that FA=O, the flag FA is set to the value 1 (step 190), and the timer is started, that is, the timer variable Ta is reset to the value 0 (step 200).

After this process or in step ]80, rNO
If it is determined to be J, the timer variable Ta is incremented by the value 1 in order to measure time by software (step 2] O).

Next, it is determined whether or not this timer variable Ta is greater than or equal to a preset reference time TO (step 220).
If the determination is "NO", the process moves to step 150, and the setting of the damping force of the shock absorber 2 is still maintained at a soft level. This timer variable Ta is incremented by 1 each time this routine is executed, so the time corresponding to the timer variable Ta is the reference time To.
For a period shorter than , the determination at step 220 is "NO".

If the answer is YES in step 220, the flag FS is reset to the value O (step 230), the damping force setting of the shock absorber 2 is switched from soft to hard (step 30), and this routine is temporarily terminated. .

That is, as shown in FIG. 6, after time t3, the determination at step 160 becomes rYESJ, and step 22
At 0, the timer variable Ta is compared with the reference time TO.
Since the period from time t3 to t4 is shorter than the reference time TO, the damping force setting is kept soft. After time t4, the determination in step 160 becomes rNOJ, and the damping force setting is still kept soft. . Time t5-t7
Similarly, the damping force setting is kept soft, but after time t7, the time during which the damping force change rate V continues to be smaller than the second reference value v2 is the reference time TO.
Therefore, the determination in step 220 is rYEs.
J, and the setting of the damping force is switched to hard at time t8, which is after the reference time TO has elapsed from time t7. Thereafter, the damping force setting is maintained at a hard level until the damping force change rate V exceeds the first reference value v1.

When the damping force control routine described above is repeatedly executed, the damping force of the shock absorber 2 of each wheel is set to a small state as soon as the damping force change rate V exceeds the first reference value v1 (see Fig. 6). After the damping force change rate V becomes equal to or less than the reference value v1 at time tl), this state remains in place until the damping force change rate V continues to be less than the second reference value v2 for 70 or more reference times (time t8). is maintained. After this time has elapsed, the shock absorber 2 is again controlled to have a large damping force.

Therefore, the suspension control device 1 of this embodiment uses a very responsive signal called the damping force change rate V to determine the damping force generation pattern of each shock absorber 2 of the vehicle.
It is possible to quickly control the vehicle to an appropriate state depending on the road surface condition. That is, [1] When driving on a flat road, even if the damping force change rate V exceeds the first reference value v1, it quickly settles to a state where V<V2, and the shock absorber 2 The time period for which the damping force characteristic is maintained in a small state is also set short. Therefore, when the vehicle crosses a small step on a flat road surface, the damping force setting returns to hard within a short time, and ride comfort is maintained. As a result, the damping force setting will not be kept soft for an unnecessarily long period of time, and the ground contact will not be impaired.

[11] On the other hand, when driving continuously on a rough road (the damping force change rate V changes greatly, not only the damping force change rate V exceeds the first reference value v1, but also the second Conditions that even exceed the reference value v2 frequently occur. Therefore, if some of the suspension characteristics are controlled to be soft, the time for which the state of V<V2 continues will be shortened, and the time for maintaining the soft state will be longer, causing damping. The frequency of force switching does not become unnecessarily high.As a result, there is no discomfort when driving the vehicle, and the durability of the shock absorber 2 is also improved.

As described above, according to the suspension control device 24-1 of the present embodiment, the characteristics of the suspension can be controlled with good responsiveness by using a highly responsive signal called the rate of change in damping force, and the The time for maintaining the damping force in a small state can be optimally switched between when going over a small step and when driving on a rough road, thereby achieving both ride comfort and handling stability of the vehicle.

Next, the second reference value V2. Standard time To
Regarding the modified example configured to switch the value of
This will be explained along with part of the flowchart shown in the figure. The illustrated processing of steps 121 to 126 is performed between step 120 and step 160 of the flowchart shown in FIG.

First, a process is performed to read the vehicle speed S from the waveform shaping circuit 73 connected to the vehicle speed sensor 51 (step 121).
It is determined whether or not this vehicle speed S is greater than a preset reference vehicle speed SO (step 122). S>5o(7
), set the second reference value V21 (step 123), and further set the value TOI to the reference time To (step 124). If S≦SO, the second reference value v2 is set to a value V22 smaller than the value V21 (step 125), and the reference time To is further set to a value TO2 larger than the value TO1 (step 126). That is, at high speeds exceeding the vehicle speed SO, the second reference value v2 is set larger and the reference time T is set larger than at low speeds below the vehicle speed SO.
This is done by setting o short. Second reference value V2. Once the reference time TO is set, the process moves to step 160 and subsequent steps described above. In other words, at high speeds (in this case, the damping force setting is made easy to switch from soft to hard).At high speeds (in general, the damping force change rate V itself becomes large), but this process is This eliminates the fear that the damping force setting will be maintained at a soft setting, and can meet the demands for hard damping at high speeds.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments in any way. For example, the second reference value v2 can be set to an absolute value on the positive side and negative side of the damping force change rate. It goes without saying that the present invention can be implemented in various ways without departing from the spirit of the invention, such as a configuration in which the values are different from each other, a configuration in which the reference time To is determined based on the peak value of the damping force change rate V, etc.

Effects of the Invention As detailed above, according to the suspension control device of the present invention, the holding period from when the damping force setting is switched from high to low until it returns is determined by the damping force change rate as the second criterion. Because it is determined based on a duration that falls within a range of values, it is extremely advantageous in that the damping force setting, which has been switched to a soft setting, can be continued for a period of time depending on the vehicle's driving conditions (e.g. road surface condition, vehicle speed, etc.). It has a great effect. Therefore, for example, when driving over a small bump on a flat road, the damping force setting tends to return to hard in a short period of time, while when driving on a rough road, the damping force setting tends to remain soft. . As a result, the damping force setting is not unnecessarily maintained at a soft setting for a long period of time, thereby impairing ground contact, and the damping force setting is not changed frequently, which may cause the driver to feel uncomfortable. Additionally, there is an advantage to the durability of the device.

[Brief explanation of drawings]

FIG. 1 is a block diagram illustrating the basic configuration of the present invention, FIG. 2 is a schematic configuration diagram showing the overall configuration of a suspension control device as an embodiment of the present invention, and FIG. 3 (A) is a shock absorber 2 Fig. 3 (B) is a partial cross-sectional view showing the structure of
) is an enlarged sectional view of the main parts of the shock absorber 2, and FIG. 4 is a block diagram showing the configuration of the electronic control device 4 of this embodiment.
FIG. 5 is a flowchart showing a damping force control interrupt routine, FIG. 6 is a graph showing an example of switching damping force settings, and FIG. 7 is a part of a flowchart showing main parts of processing in another embodiment. . 1...-Suspension control device 2 FL, FR, RL, RR...Shock absorber 4...Electronic control device 25 FL, FR, RL, RR...Piezo load sensor 27 FL, FR, RL, RR・... Piezo actuator 51 ... Vehicle speed sensor 8 70 ... Damping force change rate detection circuit 75 ... High voltage application circuit 79 ... High voltage power supply circuit

Claims (1)

[Claims] 1. A shock absorber that is installed in the suspension of a vehicle and can set a damping force generation pattern, a damping force change rate detection means that detects the rate of change in the damping force of the shock absorber, and a damping force change rate detection means that detects the rate of change in the damping force detected by the shock absorber. and damping force control means for changing the setting of the damping force of the shock absorber based on the magnitude relationship between the damping force and the reference value for adjusting the damping force. damping force switching means for changing the setting of the damping force of the shock absorber from large to small when it is determined that the rate of change of is outside the range of the first reference value; and setting of the damping force by the damping force switching means. When it is determined that the rate of change of the damping force has continued for a predetermined period or longer within the range of a second reference value whose absolute value is smaller than the first reference value after the damping force has been changed to a small value, the damping force A suspension control device comprising a damping force return means for changing the setting of the damping force from small to large.