JPH02182523A - Suspension device for car - Google Patents

Abstract

PURPOSE:To improve operational safety by establishing a target load inputted from the upper and lower sides of a spring into a cylinder on a stroke between the upper and lower sides of the spring, a static load and correction value to control the change of the attitude of a car body, and controlling the supply and discharge of fluid for the cylinder according to the above target load. CONSTITUTION:In a suspension device whose suspension characteristics is changed by controlling the supply and discharge of fluid for hydraulic chambers 4, 5 of a hydraulic cylinder 3 installed between the upper and lower sides of a car spring, the device is provided with a load detecting means 21 for load inputted into the hydraulic cylinder 3 and a stroke detecting means 23 for a stroke between the upper and lower sides of the spring. Each detection signal is inputted into a control means 29, where a target load Fr inputted into the hydraulic cylinder 3 is determined from an equation of Fr=Fo+K.(H-X)+alpha, and the supply and discharge of the fluid into the hydraulic chambers 4, 5 is controlled to realize the target load Fr. In the above equation, Fo, H, K and alpha denote a static load, a reference stroke, factor and correction value to control the change of the attitude of a car body respectively.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention supplies and discharges fluid to and from fluid chambers of fluid cylinders installed between a vehicle body (spring mass) and each wheel (spring mass). The present invention relates to a suspension device in which suspension characteristics are controlled using the following methods.

(Prior Art) Conventionally, as an example of a suspension system for this type of vehicle, as disclosed in Japanese Patent Publication No. 59-14365, a hydraulic cylinder is disposed between the vehicle body and each wheel, and A so-called hydropneumatic suspension device is known in which a gas spring is connected to the hydraulic cylinder so that the vertical load of the suspension is absorbed by the compressibility of the gas in the gas spring.

On the other hand, there is no gas spring connected to the cylinder, and a pressure source such as a pump is communicated with the fluid chamber of the cylinder via a fluid passage, and the supply and discharge of fluid to and from the cylinder fluid chamber is controlled in the middle of the fluid passage. A control valve is installed, and by controlling this control valve, fluid is supplied and discharged from the fluid chamber of each cylinder to change the suspension characteristics, thereby improving ride comfort and stabilizing the vehicle body posture. Active suspension devices are known.

(Problem to be Solved by the Invention) In the above active suspension device, the target value of the stroke between the sprung mass and the unsprung mass is set based on the internal pressure of the cylinder and the displacement speed of the suspension stroke, and the target stroke is determined based on the cylinder internal pressure and the displacement speed of the suspension stroke. There is a control method for controlling the supply and discharge of fluid to and from the fluid chamber of the cylinder so that the following is achieved. However, in reality, human force is applied to the suspension when the vehicle passes over uneven road surfaces, turns, and accelerates/decelerates. In other words, when the road surface rises, the load input to the suspension increases and the vehicle body is pushed up, and when turning, the load input from the vehicle body to the suspension increases due to lateral acceleration, causing the vehicle to roll. Therefore, rather than controlling the stroke between the upper and lower springs, it is more effective to control the load applied to the suspension.

When performing such load control, the inventors set the target load input to the cylinder as the load (static load) when the cylinder is stopped, etc., in order to block the load input from the road surface, and We have considered a method of controlling the vehicle so that the load reaches the target load, but with this method, it is difficult to maintain a constant posture of the vehicle body. Therefore, it is conceivable to further set the target load by adding a correction amount to make the vehicle body posture constant.

That is, the target load is set using the following equation, where the static load is FOL, the reference stroke (reference vehicle height) between the sprung and unsprung parts is H1, the actual stroke is xl, and the coefficient corresponding to the spring constant is K.

Fr = FO1K ・(H-x) ・・− ■However, according to this method, if the load from the road surface and the load from the vehicle body due to acceleration during acceleration/deceleration or turning are simultaneously input to the suspension, , the response to one of the loads is reduced, resulting in poor ride comfort and reduced steering stability. Specifically, for example, when a change in the vehicle body posture is suppressed in response to lateral acceleration during a turn, if there is a change in the road surface, the response to the change in the road surface becomes poor, and the vehicle is unable to absorb the load properly. However, the ride comfort will be sacrificed.

The present invention has been made by further pushing forward the concept of load control, and its purpose is to improve the method of setting the target load when controlling the input load to the suspension. The aim is to achieve both improvement in riding comfort and improvement in handling stability through the use of a device.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention adds a correction term for suppressing changes in vehicle body posture to the equation for setting the target load, and uses this correction term to Have them deal with changes in their posture.

That is, specifically, as shown in FIG.
In the invention described in 1), the extensible fluid cylinder 3 installed between the sprung portion and the unsprung portion of the vehicle is provided, and fluid is supplied and discharged from the fluid chamber 4.5 of the fluid cylinder 3 to improve the suspension characteristics. In a suspension device configured to change and adjust the suspension, a stroke detection means 23 is provided for detecting the stroke X between the sprung mass and the sprung mass.

Further, a load detection means 21 is provided for detecting the load input to the fluid cylinder 3 from the sprung portion and the unsprung portion.

Then, the output signal of the rain detection means 21.23 is input, and the target load Fr input to the cylinder 3 from the sprung and unsprung parts is calculated as follows: Fr = Fo +K ・(H−x) +α − ・・
■Fo: Static load H: To the standard vehicle height: Coefficient α: Set based on the formula of the correction amount to suppress changes in the posture of the vehicle body, and the load detection means 2
A control means 29 is provided for controlling supply and discharge of fluid to and from the fluid chamber 4.5 of the cylinder 3 so that the detected load detected by the cylinder 1 becomes the target load Fr.

The correction amount α changes depending on the acceleration applied to the vehicle body when the vehicle turns, accelerates or decelerates, the acceleration applied to the unsprung portion due to unevenness of the road surface, etc.

In addition, in the invention described in claim (2), the above-mentioned claim (1)
In addition to the configuration of the invention described above, the present invention is characterized in that a coefficient variable means 30 is provided for varying the coefficient of the target load setting formula (2) in the control means 29.

(Function) With the above configuration, in the invention described in claim (1), in the control means, the stroke x1 correction amount α between the upper and lower springs detected by the stroke detection means 23, the static load ffi
Based on F o and the reference vehicle height H, the target load Fr is set using the above equation 0. Then, this target load Fr and the actual load detected by the load detection means 21 are compared, and the supply and discharge of fluid to and from the fluid chambers 4 and 5 of the cylinder 3 is controlled so that the actual load becomes the target load Fr. .

In this case, since the correction amount α for suppressing the change in the posture of the vehicle body is added to the setting formula (2) for the target load Fr, the change in the posture of the vehicle body is suppressed by the amount corrected by the correction amount α. Therefore, even when the load from the road surface and the load from the vehicle body due to acceleration during acceleration, deceleration, or turning are input to the suspension at the same time, the response to one of the loads does not deteriorate, which improves ride comfort. It is possible to simultaneously improve handling stability. In addition, since the correction amount α related to the vehicle body posture and the control amount for absorbing road vibration are separated in this way, it is possible to improve control responsiveness and simplify the control system. It is also possible to freely change the setting of the correction amount α to keep the posture stable.

In addition, in the invention set forth in claim 2, the coefficient in the target load setting formula (2) can be made variable by the coefficient variable means 30, so that when the input of road surface change is small, the coefficient can be changed by changing the coefficient. You can set the coefficient to a large value to improve steering stability, while when the input of road surface changes is large, you can set the coefficient to a small value to improve ride comfort.
Therefore, ride comfort and steering stability can be further improved.

(Example) Hereinafter, an example of the present invention will be described based on the drawings from FIG. 2 onwards.

FIG. 2 schematically shows the overall structure of a suspension device according to an embodiment of the present invention. In the figure, 1 is a vehicle body constituting a sprung portion of the vehicle, 2F is a front wheel, and 2R is a rear wheel. Each of these wheels 2F and 2R is supported by a wheel support member (not shown) such as an axle. Additionally, each of the wheels 2F, 2R and the wheel support member constitute an unsprung portion.

The vehicle body 1, that is, the sprung portion, and each wheel 2F.

An extendable hydraulic cylinder 3 is installed between the unsprung portion including 2R. As shown in FIG. 3, each cylinder 3 includes a cylinder body 3a connected and fixed to the wheel support member (wheels 2F, 2R), and a cylinder body 3a that is reciprocatably fitted into the cylinder body 3a. The piston 3b partitions the inside of the piston 3a into upper and lower hydraulic chambers 4 and 5. A piston rod 3C extending upward is integrally connected to the piston 3b, and the upper end of the piston rod 3c is connected and fixed to the vehicle body 1 via a load sensor 21 for detecting a load F applied to the suspension. In this embodiment, the load sensor 21 allows
Load detection means is configured to detect the load F input to the cylinder 3 from the sprung and unsprung portions.

Further, the upper and lower hydraulic chambers 4.5 of each cylinder 3 are communicated via oil passages 6, 7, respectively, with an oil pump 8 and a reserve tank 9, which are driven by an on-vehicle engine (not shown). In the middle of the oil passage 6.7, supply and discharge of oil to and from the hydraulic chamber 4.5 of the cylinder 3 is controlled. The same number (4) of control valves 10 as wheels 2F and 2R
．． 10°... is arranged. Each of the control valves 10 is a proportional solenoid valve having three switching positions, and by controlling the switching positions (PID control), supply and discharge of oil to and from the hydraulic chambers 4.5 of each cylinder 3 is controlled. .

The operation of each of the control valves 10 is controlled by a CPU-incorporated controller 22 provided corresponding to each wheel 2F, 2R. This controller 22 includes
The detection signal of the load sensor 21, the detection signal of the stroke sensor 23 that detects the expansion and contraction stroke of the cylinder 3 corresponding to the wheels 2r-, 2R, the signal of the vehicle speed V output from the vehicle speed sensor 24, and the vehicle body 1 (spring The detection signal of the longitudinal g sensor 25 that detects the longitudinal acceleration gFR acting on the upper part), the detection signal of the lateral g sensor 26 that similarly detects the lateral acceleration gRL, and the Detecting the acting vertical acceleration guo 4
Detection signals from two unsprung g-sensors 27°27,...
A switching signal for a mode lever switch 28 for switching the vehicle body roll characteristics when the vehicle turns is input.

The mode lever switch 28 is turned on to suppress the amount of body roll or to reverse the roll characteristics. Further, the stroke sensor 23 has a sensor main body 23a fixed to the vehicle body 1, and a movable part 23b slidably inserted into the main body 23a. The movable part 23b
is connected to the body 3a of the corresponding cylinder 3 via a rod 23c, and detects the expansion/contraction stroke of the cylinder 3 based on the displacement of the movable portion 23b that changes with the expansion/contraction movement of the cylinder 3. In this embodiment, the stroke sensor 23 constitutes a stroke detection means that detects the actual stroke X between the sprung mass and the sprung mass.

Now, to explain the control of the supply and discharge of oil to and from the hydraulic chambers 4.5 of each cylinder 3 in the controller 22, the control procedure is performed according to the flowchart shown in FIG. 3. First, in step S1, the vehicle speed V is measured, and in the next step S2, the vehicle speed V is V-0 (while stopped).
Determine whether or not. When this determination is YES in v-0, the process proceeds to steps 83 to S6 and stroke control is performed. This stroke control involves switching control (PI) of each control valve 10 so that the actual stroke X becomes the reference vehicle height H.
D control) to supply and discharge oil to and from the upper and lower hydraulic chambers 4.5 of the cylinder 3. First, in step S3, the set flag SF is set to SF-0, and then in step S4
The standard vehicle height H set in advance is set as the target stroke xr.
Set to .

After that, in step S5, the actual stroke X detected by the stroke sensor 23 is measured, and in step S5, the actual stroke X detected by the stroke sensor 23 is measured.
In step 6, the valve operation amount is calculated based on the difference between the target stroke xr and the actual stroke X (PID calculation). Thereafter, the process proceeds to step S7, where an operation signal is output to each control valve 10 to perform PID control of the valve 10.

On the other hand, if the vehicle is in a running state and the step S2 is
When it is determined that V≠0 (NO), load control is performed. This load control is performed by setting the static load Fo and the reference vehicle height H, determining the actual stroke X at each wheel 2F and 2R, and calculating the difference between the reference vehicle height H and the actual stroke X using the above formula The total amount of the value K・(H−x) multiplied by the coefficient, the static load F, and the correction amount α is set as the target load Fr, and the load sensor 2
The control valve 10 is switched and operated to control supply and discharge of oil to the upper and lower hydraulic chambers 4 and 5 of the cylinder 3 so that the actual load F detected by the cylinder 1 becomes the target load Fr.

Specifically, first, in step S8, it is determined whether the set flag SF is 5F-0. This judgment is 5F
When the answer is YES (SF≠0), the process proceeds to step S+2 after passing through steps 89 to Sl+, and when the answer is No (SF≠0), the process immediately proceeds to step S+2. In the above step S9, the load F detected by the load sensor 21 is measured, and in the next step SIO, the load F is set as the static load FO, and further, in step Sl+, the set flag SF is set to 5F-1.

Therefore, the static load FO is determined when the vehicle is started from a stop.

Then, in step S12, the stroke sensor 2
Actual stroke X detected by 3 and longitudinal g sensor 2
5, the left and right acceleration gRL detected by the left and right g sensor 26, and each unsprung g
The spring lowering acceleration guo detected by the sensor 27 is 711J in total. Next, the process proceeds to step SI3, where it is determined whether or not the spring-lowering acceleration guo is higher than the set value Gl.

If this determination is YES with guo>G+, step S
In Step 14, set the coefficient to ml set value to 1, and if guO≦G1 is No, set the coefficient to 2 (>Kl) in step S+5 to the above-mentioned first set value and a second set value larger than 1. , and then proceeds to step SI6. In this step S16, it is determined whether the mode lever switch 28 is turned on. This judgment turns on the switch
When the answer is YES, the process proceeds to step S+7, and the coefficient Kb corresponding to the vehicle speed V is calculated using the preset map 1. When the answer is NO (the switch is OFF), the process proceeds to step S+7, where the coefficient Kb corresponding to the vehicle speed V is calculated using the map 2. Ask for each. The coefficient Kb determines the roll characteristics (change in posture in the vehicle width direction) of the vehicle body 1.

In maps 1 and 2 above, the coefficient Kb is set according to the vehicle speed V, and in both maps, the coefficient Kb decreases from the value that causes the vehicle body 1 to be in a reverse roll state as the vehicle speed V increases in the low speed range. In a high speed range of a predetermined vehicle speed or higher, the coefficient Kb is set to a constant value corresponding to a zero roll state.

Further, the degree of decrease of the coefficient Kb in the low speed range is set to be larger in map 1 than in map 2.

After this, in step srs, the target load Fr is set based on the above equation (2). In that case, the correction amount α is set corresponding to each wheel. This target load ff1Fr is set for each wheel 2F.
, 2R is shown as follows. Note that Ka is a coefficient that determines the change in the posture of the vehicle body 1 in the longitudinal direction, and Kc is a coefficient that determines the change in the posture of the vehicle body 1 due to the vertical acceleration gLID of the lower spring.

"Left front wheel" Fr=Fo+-(H-X) -Ka-gFR-Kb0gRL -Kc-guo...■(ff-
-Ka ” gFR-Kb ” gRLKCIlguo
) "Right front wheel" Fr = Fo + - (H-x) -Ka・gFR+KbogRL -Kc-guo ・・・■(α--K
a IIg+-R+Kb #gRL-Ke 0guo) "Left rear wheel" Fr =Fo+@(H-x) +Na・gFR-Kb@gRL -Kc"guo,...■(α-Ka
QgFR-Kb@gRL -KC"guo) "Right rear wheel" Fr=Fo+K・ (H-x) +Na ψgFR+Kb 0gRL-Kc 0g
uo ・・・■Ca-Ka a
gr: R+Kb -gRL-Kc ・guo) Furthermore, in step s2o, the actual load F is measured again, and in the next step S21, the valve operation amount is calculated based on the difference between the target load Fr and the actual load F (PID calculation).

After that, the process proceeds to step S7 and each control valve 10 is
The valve 10 is controlled by PID by outputting an operation signal to the valve 10.

Therefore, in this embodiment, the correction amount α for suppressing the attitude change of the vehicle body 1 is set in steps S+6 to S+9 in the above control procedure.

Also, steps S+9 to S21. In S7, the output signals of the stroke sensor 23 and the load sensor 21 are input, and the target load Fr is set based on the above equation (2), and the actual load F detected by the load sensor 21 is set to the target load Fr. Hydraulic chamber 4.5 of cylinder 3 so that
A control means 29 is configured to control supply and discharge of oil to and from.

Furthermore, steps SI3 to SI5 constitute a coefficient variable means 30 that varies the coefficient of the target load setting formula (2) in the control means 29 in accordance with the spring lowering acceleration guo.

Next, the operation of the above embodiment will be explained.

When the vehicle is running, each load sensor 2
1. Each stroke sensor 23, front and rear g sensor 25, left and right g sensor 26, each unsprung g sensor 27, and vehicle speed sensor 2
4 output signals are input. In this controller 22, longitudinal acceleration gFR1, lateral acceleration gRL, and spring lowering acceleration gu.

And the correction amount α is calculated from the vehicle speed V for each wheel 2F.

It is calculated every 2R, and the correction amount α, the measured static load FQ and reference vehicle height H, and the stroke sensor 2
Based on the actual stroke X detected in step 3, the target load Fr is determined. Then, the target load Fr and the actual load F detected by each load sensor 21 are compared, and each control valve 10 is PID-controlled so that the actual load F becomes the target load Fr. Oil is supplied and discharged to and from 5.

In this case, target load I! When setting rFr, the control amount FO+K・(
Since the correction amount α for suppressing the attitude change of the vehicle body 1 is added to H−x), the attitude change of the vehicle body 1 is suppressed by the amount corrected by the correction amount α. Therefore, even when the load from the road surface and the load from the vehicle body 1 due to acceleration during acceleration, deceleration, or turning are input to the suspension at the same time, the response to one of the loads does not deteriorate, for example, when turning. Even when there is a change in the road surface, the reaction to the change in the road surface can be ensured and the load can be well absorbed, thereby making it possible to simultaneously improve ride comfort and handling stability.

In addition, by separately determining the correction amount α related to the vehicle body posture and the control amount for absorbing road vibration in this way, it is possible to improve the responsiveness of the control, and
The control system can be simplified, and the attitude of the vehicle body 1 can be changed in various ways by freely changing the setting of the correction amount α.

Furthermore, in setting the target load Fr, the coefficient K corresponding to the spring constant is switched by the coefficient variable means 30 according to the spring-lowering acceleration guo. That is, when the spring lowering acceleration guo is larger than the set value G1,
It is determined that the vehicle is traveling on a road surface with large variations in unevenness, and the first set value of the coefficient is set to 1 and becomes low. This low coefficient K reduces the spring constant of the suspension, allowing the unsprung portion to respond sensitively to unevenness on the road surface, thereby improving ride comfort. On the other hand, when the spring lowering acceleration guo is less than or equal to the set value 61, it is determined that the vehicle is traveling on a road surface with small changes in unevenness, and the coefficient is set to a high value with a second set value of 2. Ru. Therefore, the spring constant of the suspension is increased, and the vehicle can run stably and its handling stability can be improved. Therefore, it is possible to simultaneously improve ride comfort and handling stability at a higher level. Note that it is also possible to linearly change the above coefficient in accordance with the road surface change input so that it becomes smaller as the road surface change input becomes larger.

Further, the roll characteristics of the vehicle body 1 when turning or the like are changed depending on the vehicle speed (2). That is, the coefficient Kb of the correction amount α in the above target load setting formula (2) is determined from map 1.2. Both maps 1 and 2 are based on the vehicle speed V in the low speed range.
The coefficient Kb decreases as the vehicle speed increases, and is set to remain constant in a high-speed range above a predetermined vehicle speed, so that the vehicle body 1 enters a zero roll state in the high-speed range and the roll is suppressed. Therefore, steering stability in high speed ranges can be improved.

Moreover, both maps 1 and 2 are connected to the mode lever switch 2.
You can switch by operating 8. That is, when the mode lever switch 28 is in the OFF state, the coefficient Kb is determined by map 2 so that the switch 28 is in the ON state.
When operated, the coefficient Kb is determined by map 1, respectively. Therefore, the roll characteristics of the vehicle body 1 in the low speed range can be freely changed according to the passenger's preference. Note that it is also possible to set this coefficient Kb not based on the map but only according to the manual operation of the occupant, and the amount of roll of the vehicle body 1 can be set freely by the occupant.

It should be noted that the present invention is not limited to the above embodiments, but includes various modifications. An example of this will be explained below.

(1) By setting the coefficient Kb in the formula that determines the correction amount α, the roll characteristics of the vehicle body during turning can be
Regardless of the increase in RL (in other words, the turning state of the vehicle), it may be always maintained at reverse roll, zero roll, or normal roll.

(2) The coefficient Kb can also be set so that the roll characteristic changes from reverse roll to zero roll to normal roll in accordance with an increase in left-right acceleration gRL.

(3) By setting the coefficient Ka of the formula that determines the correction amount α, the correction amount α can be adjusted to accelerate or decelerate between the front wheel 2f side and the rear wheel 2R side! ' (for example, detected by the longitudinal acceleration gFR).

For example, during acceleration, the correction amount on the rear wheel 2R side is set to α, and the correction amount on the front wheel 2F side is set to 1α, and when decelerating, the correction amount on the front wheel 2F side is set to α, and the correction amount on the rear wheel 2R side is set to α. The correction amount is set to 1 α.

By doing so, it is possible to suppress changes in the posture of the vehicle body 1 during acceleration and deceleration.

(4) In that case, the acceleration/deceleration state can also be detected by the rate of change in vehicle speed instead of the longitudinal acceleration gFR.

(5) The correction amount α may be made variable according to the spring lowering acceleration guo by setting the coefficient Kc of the formula for determining the correction amount α. For example, the spring lowering acceleration gu
The correction amount α is increased as o increases.

(6) Also, the spring lowering acceleration gu on the front wheel 2F side.

As the unsprung end acceleration guo of the rear wheel 2R side, the unsprung end acceleration guo of the front wheel 2F side is delayed by the predetermined time required for the vehicle to move forward by the wheel base and used. do.

With this method, the longitudinal g sensor on the rear wheel 2R side can be made unnecessary.

(7) Furthermore, when the longitudinal g sensor °25 on the rear wheel 2R side fails, the spring lowering acceleration guo on the front wheel 2F side is delayed by the predetermined time required for the vehicle to move forward by the wheelbase. Thereby, even when the longitudinal g sensor 25 on the rear wheel 2R side is out of order, the unsprung stop acceleration guo on the rear wheel 2R side can be input.

(8) Furthermore, one wheel stroke sensor 23
If an abnormality occurs in the wheel, the target load Fr for that wheel is set using only the static load Fo and the correction amount α, and control is performed. That is, the remaining three wheel stroke sensors 23, 23 . Since the control based on the detected amount of... is executed normally, the attitude control of the vehicle body can be ensured.

(Effects of the Invention) As described above, according to the invention described in claim (1), suspension characteristics are changed by supplying and discharging fluid to the fluid chamber of the fluid cylinder between the sprung part and the unsprung part of the vehicle. In the active suspension system, the target load input to the cylinder from the top and bottom of the spring is set based on the stroke between the top and bottom of the spring, the static load, and the correction amount to suppress changes in the posture of the vehicle body, and the actual load is added to the target load. By controlling the supply and discharge of fluid to and from the cylinder's fluid chamber so that they match, the load from the road surface and the load from the vehicle body due to acceleration during acceleration, deceleration, and turning are input to the suspension at the same time. Even when the load on the other side is lowered, the response to the load on the other side does not deteriorate, and both ride comfort and handling stability can be improved. In addition, by separating the correction amount related to the vehicle body posture from the control amount for absorbing road vibration, it is possible to improve responsiveness and simplify the control system, and it is possible to achieve freedom in changing the setting of the correction amount. .

Furthermore, in the invention described in claim (2), since the coefficient corresponding to the spring constant in setting the target load can be made variable, by changing the coefficient, ride comfort and handling stability can be improved to a higher level. can be improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of the present invention. Figure 2 and the following drawings show embodiments of the present invention, Figure 2 is an explanatory diagram showing the overall configuration, Figure 3 is a system diagram showing the configuration of the control system, and Figure 4 is the signal processing procedure in the controller. It is a flowchart figure which shows. 1... Vehicle body 2F, 2R... Wheel 3... Hydraulic cylinder (fluid cylinder) 485... Hydraulic chamber (fluid chamber) 10... Control valve 21... Load sensor (load detection means) 22 ... Controller 23 ... Stroke sensor (stroke detection means) 2
9... Control means 30... Coefficient variable means

Claims (2)

[Claims] (1) A suspension device comprising an extendable fluid cylinder installed between the sprung and unsprung parts of a vehicle, and supplying and discharging fluid to and from the fluid chamber of the fluid cylinder to change and adjust suspension characteristics. , a stroke detection means for detecting the stroke x between the sprung mass and the unsprung mass, a load detection means for detecting the load input to the fluid cylinder from the sprung mass and the sprung mass, and output signals of both of the above detection means are input. Then, the target load Fr input to the cylinder from the sprung and unsprung parts is as follows: Fr=Fo+K・(H-x)+α Fo: Static load H: Reference stroke K: Coefficient α: Correction amount to suppress changes in vehicle body posture. The present invention is characterized by comprising a control means for setting based on a setting formula and controlling supply and discharge of fluid to and from the fluid chamber of the cylinder so that the load detected by the load detection means becomes the target load Fr. Vehicle suspension equipment. (2) A suspension device comprising an extendable fluid cylinder installed between the sprung and unsprung parts of the vehicle, and supplying and discharging fluid to and from the fluid chamber of the fluid cylinder to change and adjust suspension characteristics. , a stroke detection means for detecting the stroke x between the sprung mass and the unsprung mass, a load detection means for detecting the load input to the fluid cylinder from the sprung mass and the sprung mass, and output signals of both of the above detection means are input. Then, the target load Fr input to the cylinder from the sprung and unsprung parts is as follows: Fr=Fo+K・(H-x)+α Fo: Static load H: Reference stroke K: Coefficient α: Correction amount to suppress changes in vehicle body posture. a control means for setting based on a setting formula and controlling supply and discharge of fluid to and from the fluid chamber of the cylinder so that the load detected by the load detection means becomes the target load Fr; and a target load setting in the control means. A suspension device for a vehicle, comprising: coefficient variable means for varying the coefficients of the equation.