JPH0234415A - Active suspension control device - Google Patents

Abstract

PURPOSE:To hold a car in appropriate attitude even though the over-spring weight distribution of the car is changing, by correcting or updating the target static load at normal straight running on the basis of the load applied between over and under the spring sensed while the car is running. CONSTITUTION:An actuator M1 is interposed between over and under the spring at each wheel of a car, and the load applied between them is adjusted in accordance with the supply/exhaust amount of working fluid. Under normal straight running, the working fluid in a specified amount for adjustment of the abovementioned load to the target static load is supplied and exhausted from a control means M2 to the actuator M1. In this arrangement the load applied between over and under the spring is sensed by a means M3. While the car is running, the target static load is corrected/updated by a means M4 on the basis of the load sensed by the means M3. Thereby the road surface turbulence to the car in running is shut off, and the car is held in appropriate attitude.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Fields] The present invention utilizes an active control technique for controlling the flow rate of working fluid supplied to and discharged from actuators constituting an active suspension.
The present invention relates to an active suspension control device that is effective for controlling a target static load in response to changes in sprung mass.

[Conventional technology] Conventionally, control energy is supplied to the suspension by using working fluid that is supplied and discharged from the outside to the actuators that make up the suspension, and performance has been further improved to suit various driving conditions. A so-called active suspension control device that achieves ideal suspension characteristics (spring constant, damping force, etc.) is known.

As such a technique, for example, "active suspension" (Japanese Utility Model Application Publication No. 63-4706) has been proposed. In other words, the offset pressure command value for the pressure control valve that controls the fluid pressure supplied to the pressure chamber of the fluid pressure cylinder interposed between each wheel and the vehicle body is set at the time when the fluid pressure source connected to the pressure control valve starts operating. The system detects the offset pressure and raises the pressure with a time constant greater than the time constant of the pressure control valve, thereby preventing the vehicle height from rapidly changing to a position corresponding to the offset pressure and causing discomfort to the occupants. .

[Problems to be Solved by the Invention] In the conventional technology, the offset pressure determined according to the static load of the vehicle is a predetermined set value that is always constant, and the pressure is gradually increased only when the engine is started, and then the pressure is suddenly increased. This was to suppress changes in vehicle height. However, in general, the static load of a vehicle changes as the vehicle travels. In other words, the amount of fuel stored in the fuel tank decreases as the vehicle travels, passengers move up and down, or change their riding position within the vehicle.
The static load of a vehicle fluctuates and is rarely held constant throughout the vehicle. Therefore, if active control is performed based on the assumption that the static load is constant, there is a problem in that the balance of the vehicle posture becomes unstable when the vehicle's sprung weight distribution changes, giving the occupants a sense of discomfort and causing a deterioration of ride comfort. However, there was still room for improvement in the conventional technology.

SUMMARY OF THE INVENTION An object of the present invention is to provide an active suspension control device that can block road disturbances to a running vehicle through active suspension control, and can maintain a favorable vehicle posture regardless of changes in the vehicle's sprung weight distribution. shall be.

[Means for Solving the Problems] The present invention, which has been made to achieve the above object, has a system that is interposed between the sprung portion and the unsprung portion of each wheel portion of a vehicle, as illustrated in FIG. ,
An actuator M1 that can adjust the load acting between the sprung mass and the unsprung mass by a predetermined amount of working fluid supplied and discharged from the outside; an active suspension control device comprising: control means M2 for supplying and discharging a working fluid to and from the actuator M1 in an amount that makes a load a target static load; load detection means M3 for detecting a load; and correction and updating means M4 for correcting and updating the target static load based on the load detected by the load detection means M3 when the vehicle is running.
The gist of the present invention is an active suspension control device comprising the following.

[Function] As illustrated in FIG. 1, the active suspension control device of the present invention adjusts the load acting between the sprung and unsprung portions of each wheel of the vehicle to a target static load during steady straight-ahead running. The control means M2 controls the amount of working fluid to be controlled by the actuator M1.
Supply and discharge to. At this time, when the vehicle is running, the load detection means M
A correction/update means M4 operates to correct and update the target static load based on the load acting between the sprung mass and the unsprung mass detected in step 3.

That is, the target static load during steady straight running is corrected and updated based on the load acting between the sprung mass and the unsprung mass detected during vehicle travel.

Therefore, the active suspension control &V system of the present invention works to correct and update the target static load in response to changes in the sprung weight distribution of the vehicle.

[Embodiment] Next, a preferred embodiment of the present invention will be described in detail based on the drawings. FIG. 2 shows a system configuration of an active suspension control device that is an embodiment of the present invention.

As shown in the figure, the active suspension control device 1 includes an actuator 5 interposed between a vehicle body 2 and a lower arm 4 that supports wheels 3, a hydraulic circuit 6 for supplying and discharging hydraulic oil to and from the actuator 5, and a hydraulic circuit. 6, and an electronic control unit (hereinafter simply referred to as ECU) 7.

The inside of the cylinder 11 of the actuator 5 is divided into an upper chamber 13 and a lower chamber 14 by a piston 12 that is slidably fitted therein. The piston rod 15 connected to the piston 12 has a communication passage 16 communicating with the upper chamber 13 at one end and a communication passage 17 communicating with the lower chamber 14 at one end. The other ends both communicate with a manifold disposed at the upper end of the piston rod 15. A male screw is threaded on the outer periphery of the upper part of the piston rod 15, and the upper part of the piston rod 15 is fixed to the vehicle body 2 by a bolt 20 via an upper support 19. On the other hand, the bottom of the cylinder 11 is rotatably connected to the lower arm 4 via a lower bush 21. In addition, in order to reduce the load burden on the actuator 5, a coil spring 22 with a relatively low spring constant is installed in the cylinder 1.
The upper support 19 is interposed between a spring seat 23 fixed to the outer periphery of the spring seat 1 and the upper support 19.

The hydraulic circuit 6 includes a hydraulic pump 33 that is driven by an on-vehicle engine 31 and sucks hydraulic oil from a reservoir 32, and an upper chamber 13 and a lower chamber 14 of the actuator 5 from the hydraulic pump 33.
Supply of hydraulic oil from the upper chamber 13 and lower chamber 14 to the reservoir 3
2 is provided with an electro-hydraulic servo valve 34 that discharges hydraulic oil to the engine 2 based on the control of the ECU 7. When hydraulic oil is supplied from the electro-hydraulic servo valve 34 to the upper chamber 13 through the conduit 36 and the communication passage 16, the piston 13 slides down inside the cylinder 11 toward the lower arm 4, and Accordingly, the hydraulic oil inside the lower chamber 14 flows through the communication passage 17.
, manifold 1 day, line 37, electrohydraulic servo valve 3
4 into the reservoir 32. As a result, the actuator 5 contracts, so the relative distance between the vehicle body 2 and the lower arm 4 is shortened. Conversely, when hydraulic oil is supplied from the electro-hydraulic servo valve 34 to the lower chamber 14 through the conduit 37, manifold 1, and communication passage 17, the piston 13 moves upward inside the cylinder 11 toward the vehicle body 2. ,
Accordingly, the hydraulic oil inside the upper chamber 13 is discharged to the reservoir 32 via the communication passage 16, the manifold, the pipe line 36, and the electrohydraulic servo valve 34. As a result, the actuator 5 is extended, so that the relative distance between the vehicle body 2 and the lower arm 4 is extended. In this way, under the control of the ECU 7, the electro-hydraulic servo valve 34 adjusts the flow rate and flow direction of the hydraulic oil to change the relative distance between the vehicle body 2 and the lower arm 4, thereby reducing the load acting on the actuator 5. can be actively controlled.

The active suspension control device 1 serves as a detector.
A load sensor 41 consisting of a piezoelectric element that detects the load acting between the actuator 5 and the vehicle body 2, a vehicle height sensor 42 consisting of a rotary encoder that detects the relative distance between the vehicle body 2 and the lower arm 4, and a vehicle speed sensor that detects the vehicle speed. 43
, a steering sensor 44 that detects the steering angle, and a throttle position sensor 4 that detects the throttle valve opening.
5. It is equipped with a stop lamp switch 46 that detects whether or not the brake pedal is operated, and a neutral start switch 47 that detects the gear position.

The detection signals of each of these sensors and switches are sent to the ECU7.
The ECU 7 controls the electro-hydraulic servo valve 34.

The ECU 7 is configured as a logic operation circuit mainly including a CPU 7a, a ROM 7b, a RAM 7c, and a backup RAM 7d, and is connected to a human output section 7f via a common bus 7e to perform human output with the outside.

The detection signals of each of the above sensors and switches are output from the human output section 7f.
On the other hand, the CPU 7a outputs a control signal to the drive amplifier 4 via the human output section 7f to control the electro-hydraulic servo valve 34.

Next, the active suspension control process executed by the ECU 7 will be explained based on the flowchart shown in FIG. This active suspension control process is carried out by the ECU7
Executed when .

First, in step 100, the load sensor detection signal F (
n) and the initial target static load (IiW(
n-1) is performed. Continued Step 1
In step 05, it is determined whether or not it is time to start active suspension control processing based on an interrupt signal from the outside or the value of a start time flag determined by other processing,
If an affirmative determination is made, the process proceeds to step 110 and subsequent steps; on the other hand, if a negative determination is made, the process waits in step 105 until the start time is reached. In step 110, which is executed when it is determined that the start time has come, a process of reading the load sensor detection signal F(n) is performed. In the following Ste Mbu 112,
Processing for reading the detection signals of each of the other sensors is performed. Next, the process proceeds to step 115, in which weighting coefficients A and B are read from a map previously stored in the ROM 7b in accordance with the detection signals of each sensor read in step 112. In the following step 120, the target silent load W(n) for the current process is calculated by the load sensor detection signal F(n), the target silent load W(n-1) for the previous process,
The remainder correction from the previous process (luY(n-1), weighting is calculated from the coefficients A and B as shown in the following equation (1). Note that the following equation (1) is performed as an integer operation. be exposed.

W(n)=(AxF(n)+BXW(n-1
)+Y(n-1))/(A+B)-(1)
In the subsequent step 125, a process is performed to calculate the remainder y(n-) of the above equation (1), which is executed as an integer operation. Next, the process proceeds to step 130, and as a guard process, the remainder correction value Y (n-1) from the previous process is used, the weighting is the coefficient A,
It is determined whether or not the sum exceeds the sum of
40, respectively. Remainder correction value Y(n-1
), but in step 135, which is executed when the weighting exceeds the sum of coefficients A and B, the remainder correction value Y from the previous processing is
(n-1) is updated to the weighted value obtained by subtracting the sum of coefficients A and B from the remainder correction value Y(n-1) from the previous processing, and the remainder correction value Y(n-1) from the previous processing is updated. 1)/(A+B)
After performing processing to limit the value to within the range of value -1 to value +1,
Proceed to step 140. In step 140, the target static load W(n) during the current processing is determined by the load sensor detection signal F.
It is determined whether or not the value exceeds (n), and if a positive determination is made, the process proceeds to step 145, whereas if a negative determination is made, step 1δ0
, respectively. The target silent load W(n) during this processing is
In step 145, which is executed when the load sensor detection signal F (n) is exceeded, the remainder correction value Y (n After performing a process of setting the value obtained by subtracting -1) as the remainder correction value Y (n) for the current process, the process proceeds to step 155.

On the other hand, in step 150, which is executed when the target silent load W(n) during the current processing is less than the load sensor detection signal F(n), the target silent load is brought closer to the load sensor detection signal. In step 1, after performing a process of setting the sum of the remainder y(n) and the remainder correction value Y(n-1) from the previous processing to the remainder correction value Y(n) during the current processing,
Proceed to step 55. In step 155, in preparation for the next process, the target static load W(n) for the current process is changed to the target static load W(n-1) for the previous process, and the remainder correction value Y for the current process is changed.
A process is performed in which each of (n) is set to the remainder correction value Y(n-1) from the previous process. In the following step 160,
In order to correct the deviation between the target silent load W(n) and the load sensor detection signal F(n) during this processing, the difference between the target silent load W(n) and the load sensor detection signal F(n') is Depending on the deviation, the voltage ΔE applied to the electrohydraulic servo valve 34
A process of calculating (n) is performed. Then step 165
The process proceeds to step 160, where the applied voltage ΔE (
After performing the process of outputting a control signal to apply n) to the drive amplifier on the fourth day, the process returns to step 105 again. Thereafter, the active suspension control process repeats steps 105 to 165 at each start time.

Next, an example of the control state of the active suspension control process will be explained with reference to the timing chart of FIG. 4. At time t1 while the vehicle is running in the grass, the load F detected by the load sensor 41 increases in steps as the passenger moves within the vehicle, as shown by the solid line in the figure. Then, the target static load W is corrected to increase and gradually increases as shown by the broken line in the figure, and becomes equal to the load F at time t2. Furthermore, at time t3, as the occupant moves within the vehicle, the load F decreases in a stepwise manner as shown by the solid line in the figure. Then, the target static load W is corrected and gradually decreases as shown by the @ line in the figure, and becomes equal to the load F at time t4. In this way, control is continued to update the target static load W to an appropriate value at any time.

In this embodiment, the actuator 5 and the hydraulic circuit 6 correspond to the actuator M1, and the ECU? The processing steps (160 to 165) executed by the ECU 7 function as the control means M2. Also, the load sensor 41 corresponds to the load detection means M3, and the ECU? and the ECU7
Processing steps (110-125, 140-1
55) functions as the correction/updating means M4.

As explained above, according to this embodiment, the target silent load W
(n) is weighted by multiplying the detected load F (n) and the previous target static load W (n-1) by coefficients A and B, and the remainder correction value Y (n-1). Active control is performed to calculate and update the target static load W(n) so that it approaches the detected load F(n), so even if the spring weight distribution changes while the vehicle is running, the vehicle attitude remains unchanged. stabilize,
Ride comfort can be improved without causing any discomfort to passengers.

This is significant because it is not adversely affected by changes in the vehicle's sprung weight distribution caused by the reduction in fuel stored in the fuel tank as the vehicle travels, the occupant's up/down, or changes in seating position within the vehicle. It shows a great effect.

Furthermore, it is possible to realize active suspension control that can satisfactorily balance road surface disturbance isolation while the vehicle is running and update of the target silent load in response to changes in the vehicle's sprung weight distribution.

Furthermore, since the calculations of the target static load W(n), remainder y(n), and remainder correction value Y(n-1) are all integer operations, even ECU7 that does not have floating-point arithmetic capability can perform digit loss. Various quantities can be calculated accurately without causing any adverse effects such as.

In addition, in this example, weighting is a coefficient A, and B is A<
A constant that satisfies the relationship B was used. However, for example, when assigning multiple weights according to driving conditions, the coefficients A and B are set in advance by RO
It is stored in M7b, and the driving condition is determined according to the detection signals of the vehicle speed sensor 43, steering sensor 44, throttle position sensor 45, stop lamp switch 46, and neutral start switch 47, and weighting is applied to suit the driving condition. It is also possible to select a narrow combination of coefficients A and B to calculate the target static load W(n). In other words, when the value of weighting coefficient A is brought closer to the value of coefficient B, the target static load change speed becomes faster; When set to a small value, the target silent load change rate becomes slow. In addition, depending on the driving condition detected from each sensor detection signal, the setting of the execution start time of the active suspension control process is changed and the execution cycle is shortened, and the target silent load change rate becomes faster. If it is extended, the target silent load change rate becomes slower. For example, vehicle speed V
An example of control when at least one of the weighting coefficients A and B and the execution cycle is changed according to the timing will be explained based on the timing chart of FIG. 5(1). When the vehicle is running at low speed, where the vehicle speed V is less than the reference vehicle speed VR, the target silent load change rate is relatively fast.

Eventually, when the vehicle speed V increases above the reference vehicle speed VR at time tll, the target silent load change rate becomes relatively slow, responds to high speed, and suppresses sudden changes in the vehicle attitude.

When the vehicle speed V decreases to the reference vehicle speed VR again at time t12, the target silent load change rate becomes relatively fast as before.

Also, depending on the vehicle speed V and the steering angle θ, weighting is performed by a coefficient A,
B. An example of control when at least one of the execution cycles is changed will be explained based on the timing chart in FIG. 5(2). When the vehicle speed V increases above the reference vehicle speed VR (time t21), the target silent load change rate becomes relatively slow. Next, when the steering angle θ exceeds the neutral steering right boundary θR (time t22), the target static load change speed changes to a medium speed on the slightly faster side, achieving a so-called anti-roll function. When the steering angle θ is within the range from the neutral steering right boundary value θR to the neutral steering left boundary value θL due to reverse steering, (
time t23-t24), the target silent load change speed is the vehicle speed V
Depending on the time again it will be relatively slow. However, when the steering angle θ exceeds the neutral steering left boundary value θL (time t24), the target static load change speed changes again to a medium speed that is a little faster, and the steering angle θ increases to the neutral steering left boundary value. When the vehicle returns to the OL non-groove state (time t25), the target silent load change rate becomes relatively slow in accordance with the vehicle speed V. Note that here, the target quiet load when the steering angle θ is equal to or greater than the neutral steering boundary value includes a dynamic load.

Furthermore, an example of the control situation when at least one of the weighting coefficients A and B and the execution cycle is changed according to the throttle position sensor detection signal TA and the stop lamp switch signal BS is shown in FIG. 5 (3). The explanation will be based on a timing chart.

With the sudden start command acceleration, the throttle valve opening TA (corresponding to the throttle position sensor signal) begins to increase (time t31), and when it exceeds the reference throttle valve opening TAR (time t32), the target static load change occurs. The speed changes to a medium speed, which is a little on the slow side, and performs a so-called anti-slip function that suppresses sudden starts. Due to this sudden start and acceleration, the vehicle speed V exceeds the reference vehicle speed VR (time t33
).

Eventually, due to the end of the acceleration state, the throttle valve opening degree TA
decreases to less than the reference throttle valve interval TAR (
Time t34). Then, since the vehicle speed V is higher than the reference vehicle speed VR, the target static load change rate is also relatively slow (
Time t34). On the other hand, when the brake pedal operation starts (time t35) and the stop lamp switch signal BS goes to high level ((shift 1)), the target silent load change speed changes to a relatively fast medium speed. , performs the so-called anti-diameter function to suppress sudden braking. Due to this sudden braking, the vehicle speed V decreases to less than the reference vehicle speed VR (time 36). Eventually, the sudden braking state ends and the stop lamp switch signal BS goes to low level ( 1 shift 0) (time t37).Then, since the vehicle speed V has decreased below the reference vehicle speed VR, the target silent load change rate becomes relatively fast (time t37).In this case, the acceleration state The target static load in the sudden braking state includes the dynamic load.In this way, weighting that suits the driving state can be done by selecting a combination of coefficients A and B, or by shortening or extending the control processing execution cycle. If the target static load W(n) is calculated in this way, so-called vehicle attitude control can be performed that sufficiently suppresses sudden changes in the vehicle attitude.

In the above embodiment, the target silent load change rate is always increased during high-speed driving, cornering, acceleration, and sudden braking to suppress sudden changes in the vehicle attitude. However, for example, when driving at high speeds, turning, accelerating, or braking suddenly, the target silent load change rate is typically slowed down, and a correction amount determined according to the driving conditions at that time is applied to the target silent load. The target load may be calculated by adjusting the amount. When configured in this way, the ride quality is improved and the vehicle'! It is possible to simultaneously suppress 2D sudden changes.

[Effects of the Invention] As described in detail above, the active suspension control device of the present invention sets the target static load during steady straight-ahead running to the load acting between the sprung and unsprung parts detected when the vehicle is running. The system is configured to perform correction and update based on the following information. For this reason,
The target static load is updated according to changes in the vehicle's sprung weight distribution, so it is possible to reduce the amount of fuel stored in the fuel tank due to a decrease in fuel as the vehicle is being driven, the occupant going up and down, or changing the riding position inside the vehicle. Even when the sprung weight distribution of a vehicle changes,
This has the excellent effect of stabilizing the balance of the vehicle's posture and enabling active control of the suspension to provide a comfortable ride that does not cause any discomfort to the occupants.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram conceptually illustrating the contents of the present invention, FIG. 2 is a system configuration diagram of an embodiment of the present invention, FIG. 3 is a flowchart showing the control, and FIGS. Figures (1), (2), and (3) are timing charts showing the state of the control. Ml...actuator, M2...load detection means,
M3--correction amount calculation means, M4--target load calculation means, M5--control means,

Claims (1)

[Scope of Claims] 1. A predetermined amount of load that is interposed between the sprung mass and the unsprung mass of each wheel portion of a vehicle and that is supplied and discharged from the outside to absorb the load that acts between the sprung mass and the unsprung mass. an actuator that can be adjusted by a working fluid, and a control means for supplying and discharging working fluid to the actuator in an amount that makes the load acting between the sprung part and the unsprung part a target static load during steady straight running; The active suspension control device further comprises a load detection means for detecting a load acting between the sprung mass and the unsprung mass, and a load detection means for detecting the load acting on the sprung mass and the sprung mass, and determining the target quietness based on the load detected by the load detection means when the vehicle is running. An active suspension control device comprising: a correction update means for correcting and updating a load;