JP2683922B2 - Suspension control device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a suspension control device that controls the attitude of a vehicle.

(Prior Art) Conventionally, various suspension control devices have been proposed for automatically suppressing rolling and the like generated in a vehicle body to stabilize the posture of the vehicle body and improve the maneuverability and riding comfort of the vehicle.

In particular, as the roll control, the suspension unit interposed between the wheel side and the vehicle body side predicts a posture change occurring in the vehicle body from the vehicle speed and the steering angle and suppresses the posture change. There is one that stabilizes the posture of the vehicle body by appropriately supplying / discharging the pressurized fluid to / from the cylinder.

A suspension control device that performs this roll control includes, for example, a lateral speed that occurs in a vehicle body at a constant steering angle based on a vehicle speed and a steering angle detected by a vehicle speed sensor that detects a vehicle speed and a steering angle sensor that detects a steering angle. Lateral acceleration estimating means for estimating the acceleration, calculating means for calculating the amount of change in the roll angle of the vehicle body and cylinder length of each suspension unit expected to occur due to the estimated lateral acceleration, and the calculated cylinder length. A logic for setting a target supply / discharge amount for supplying / discharging the pressure fluid according to the amount of change in pressure Some have a control device composed of a computing means. Then, in this suspension control device, the supply / discharge valve is opened based on the valve-opening time set by the logical operation means for every constant steering angle, and the pressure fluid is supplied / discharged to / from the cylinder to control the attitude of the vehicle body.

(Problems to be Solved by the Invention) However, the above-described conventional suspension control device has the following problems.

Rolling occurs because the load moves laterally in proportion to the lateral acceleration when the vehicle turns, so that the pressure in the cylinder of each suspension unit changes. That is, as shown in FIG. 11, when the vehicle turns to the left, the load moves to the right and the right cylinder internal pressure increases and the left cylinder internal pressure decreases.

In the above-described conventional suspension control device, when the vehicle turns to the left, the steering wheel in the turning direction (steering in the direction to increase the steering angle when the steering angle in the straight traveling direction is 0) is moved to the right cylinder. The control to supply the pressure fluid and to discharge the pressure fluid from the left cylinder is performed, but by opening the supply / discharge valve at the valve opening time set from the predicted lateral acceleration, the cylinder pressure on the right side becomes Since the pressure fluid is rising, the pressure fluid cannot be sufficiently supplied, and since the pressure inside the cylinder on the left side is decreasing, the pressure fluid is not sufficiently discharged.

Further, during steering in the return direction (steering in the direction of returning to the steering angle of 0 in the straight ahead direction), pressure fluid is discharged from the right cylinder and pressure fluid is supplied to the left cylinder. If the valve time supply / discharge valve is opened, the pressure fluid in the right cylinder will be discharged more than the set amount due to the high internal pressure, and the pressure fluid will be supplied in excess of the set amount due to the low internal pressure in the left cylinder. I will end up.

As described above, in the conventional control device, it is not possible to supply and discharge an appropriate amount of pressure fluid to each cylinder due to the fluctuation of the cylinder internal pressure, so that there is a problem that the posture change of the vehicle body due to rolling cannot be accurately controlled.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a suspension control capable of reliably performing attitude control of a vehicle by supplying and discharging a pressure fluid in an amount corresponding to a cylinder internal pressure. To provide a device.

(Means for Solving the Problems) A suspension control device of the present invention connects a pressure fluid supply source to a cylinder of a suspension unit interposed between a vehicle body side and a wheel side, and outputs a signal from the control device. In a suspension control device capable of controlling the attitude of a vehicle body by operating valve means to supply and discharge the cylinder pressure fluid, the controller suppresses a change in the attitude of the vehicle body that is expected from a vehicle speed and a steering angle. The logical operation means for setting the valve opening time or valve opening amount of the valve means for setting the supply / discharge amount of the pressure fluid to be supplied to / discharged from the cylinder, and the present steering with respect to the steering angle at the time of straight traveling Steering direction determining means for determining steering or return steering, and when the steering direction determining means determines that the steering is in the turning direction, the valve opening time of the valve means is set long or the valve opening amount is set large. And a resetting means for setting the valve opening time shorter or the valve opening amount smaller when the steering direction judging means judges the return steering.

(Operation) With this configuration, when the steering direction determination unit determines that the steering direction is the turning direction steering, the resetting unit lengthens the valve opening time of the valve unit or increases the valve opening amount in order to increase the supply / discharge amount of the pressure fluid. As a result, the pressure fluid can be supplied to and discharged from the cylinder at an appropriate amount. Further, when the steering direction determination means determines that the steering is in the return direction, the resetting means shortens the valve opening time of the valve means or reduces the valve opening amount in order to reduce the supply / discharge amount. An appropriate amount of pressure fluid can be supplied to and discharged from the cylinder without supplying or discharging a large amount of pressure fluid.

(Example) Next, the Example of this invention is described based on drawing.

First, the overall configuration of the suspension control device 1 of the present embodiment will be described with reference to FIG. 2. The cylinders (hydraulic cylinders) 3a attached to the vehicle body are respectively attached to the above-mentioned 2a, 2b and the rear wheels 2c, 2d. , 3b, 3c, 3d piston rod 4a,
4b, 4c, 4d are attached, and the wheels 2a, 2b, 2c, 2d are expanded and contracted by supplying and discharging pressure fluid to and from the cylinders 3a, 3b, 3c, 3d to expand and contract the piston rods 4a, 4b, 4c, 4d. It is possible to raise and lower the vehicle height by moving relative to the vehicle body.

Each cylinder 3a, 3b, 3c, 3d includes accumulators 5a, 5b, 5c, 5d, which are spring elements, and throttle valves 6a, 6 which generate damping force.
b, 6c, 6d are connected to form a suspension unit. The cylinders 3a, 3b, 3c, 3d are connected to the pressure fluid supply source 7 via supply / discharge valves 8a, 8b, 8c, 8d as valve means, and supply / discharge valves 8a, 8b, 8c, 8d Is an electric switching valve (on / off valve) controlled by the controller 9. In addition,
10a, 10b, 10c, 10d are vehicle height sensors that are attached to the cylinders 3a, 3b, 3c, 3d and their piston rods 4a, 4b, 4c, 4d to detect expansion and contraction, 11 are vehicle speed sensors that measure vehicle speed, 12 Is a steering angle sensor for detecting a rotation angle of a steering wheel (hereinafter referred to as a steering wheel), which will be described in detail later. The detection signals detected by the respective sensors 10a, 10b, 10c, 10d, 11, 12 are control devices. 9 is input.

The steering angle sensor 12 is, as shown in FIGS. 3 to 5,
It is composed of two photo interrupters 14 and 15 fixed to the steering column 13 and a slit plate 17 fixed to the steering shaft 16. The photo interrupters 14 and 15 are slits 17a formed in the slit plate 17. An ON signal is generated when is detected, and an OFF signal is generated when a portion other than the slit 17a is detected. The angle of the slit plate 17 in the rotation direction of the slit 17a and the angle between the adjacent slits 17a are set to 2θ ₁ , and the two photo interrupters 14 and 15 are arranged as shown in FIG. Signal A generated from interrupter 14
Then, the signal B generated from the photo interrupter 15 is attached so that it is generated with a shift of 1/4 cycle.

Next, the control device 9 will be described with reference to FIG. 1. Based on the vehicle speed detection signal from the vehicle speed sensor 11 and the steering angle detection signal from the steering angle sensor 12, which are input to the control device 9. , The constant steering angle θ expected to occur on the vehicle body
A lateral acceleration estimating means 18 for estimating the lateral acceleration for each _one is provided. This estimation is based on the fact that the lateral acceleration generated in the vehicle body is proportional to the steering angle and proportional to the square of the vehicle speed.

Further, in the control device 9, there is a proportional relationship between the lateral acceleration generated in the vehicle body and the roll angle, and from this relationship, the calculation means 19 for calculating the roll angle based on the lateral acceleration.
Is provided. Furthermore, if the roll angle is calculated,
The amount of change in the length of each cylinder 3a, 3b, 3c, 3d due to the roll angle is also calculated.

The control device 9 has a cylinder calculated as above.
Each cylinder 3a, 3a, 3b, 3c, 3d to suppress the change in length
The amount of pressure fluid to be supplied to and discharged from 3b, 3c, 3d (target supply / discharge amount) is determined, and the supply / discharge time T (v) of the pressure fluid for each constant steering angle θ _{1 is} set based on the target supply / discharge amount. Logical operation means 20
Is provided. This supply / discharge time is the same as the supply / discharge valves 8a, 8b, 8
It is the time to keep c, 8d open.

Further, the control device 9 is provided with a steering direction determination means 21 that determines whether the current steering is steering in the turning direction or steering in the returning direction based on the detection signal from the steering angle sensor 12. The determination method by the steering direction determination means 21 is performed as follows.

That is, as shown in FIG. 6, when steering to the left, the detection signal B from the steering angle sensor 12 changes from ON to OFF.
When the signal changes to, signal A is in the ON state, and signal A is from ON to OF
When it changes to F, signal B is OFF, when signal B changes from OFF to ON, signal A is OFF, signal A is OFF
When it changes from ON to ON, the signal B is in the ON state. Therefore, if these four states are detected, it can be determined that the steering wheel has been rotated to the left (steering to the left). Also, when steering to the right, the signal A
When changing from ON to OFF, signal B is in the ON state, signal B
When A changes from ON to OFF, the signal A is in an OFF state, when the signal A changes from OFF to ON, the signal B is in an OFF state, and when the signal B changes from OFF to ON, the signal A is in an ON state. Therefore, if these four states are detected, it can be determined that the steering wheel has been rotated to the right (steering to the right). When the steering to the left is + (plus) and the steering to the right is- (minus), the position at which either signal A or B changes ON-OFF and the position at which the steering wheel is rotated by θ ₁ Therefore, if the added value is +, it is determined that the steering wheel is on the left side, and if the added value is −, the steering wheel is on the right side. Further, it is possible to determine whether the steering is in the turning direction or the steering in the returning direction by the determination of the position of the steering wheel and the determination of the steering in either the left or right direction depending on the ON-OFF state of the signals A and B. ..

Further, in the control device 9, when the steering direction determination means 21 determines that the steering is in the turning direction, the valve opening time T (v) set by the logical operation means 20 is reset for a predetermined time, and the return direction is set. There is provided resetting means 22 for resetting the valve opening time T (v) set by the logical operation means 20 to be shorter by a predetermined time when it is judged that the steering is being performed. In the present embodiment, this setting is reset to twice the feeding / discharging time set by the logical operation means 20 when steering in the turning direction, and 1/2 of the feeding / discharging time when steering in the returning direction.
It has been reset to double.

Incidentally, these lateral acceleration estimating means 18, calculation means 19, logical operation means 20, steering direction determination means 21, resetting means 22,
It is controlled by the CPU 23 provided in the control device 9 according to a predetermined program.

The operation of the control device 9 having the above configuration will be described with reference to the flowchart of FIG.

The detected values from the vehicle speed sensor 11 and the steering angle sensor 12 are input to the control device 9 in step, and the lateral acceleration estimating means 18 estimates the lateral acceleration generated in the vehicle body from the steering angle and the vehicle speed in step. And the calculation means in steps
The roll angle of the vehicle body is estimated from the lateral acceleration estimated in step 19 and the change in length of the cylinders 3a, 3b, 3c, 3d is calculated in step 19 by the calculation means 19.

Then, in step S1, the valve opening time T of the supply / discharge valves 8a, 8b, 8c, 8d for setting the supply / discharge amount of the pressure fluid by the logical operation means 20.
(V) is set, and in step, the steering direction determination means 21 determines whether the current steering is steering in the turning direction or steering in the returning direction. Next, in step, if the steering direction determined by the resetting means 22 is steering in the turning direction, the valve opening time T (v) set in step is doubled and reset, and the steering direction is returned. In the case of steering in the direction, the valve opening time T (v) set in the step is halved and reset. Then, the supply / discharge valves 8a, 8b, 8c, 8d are controlled in steps on the basis of the reset valve opening time, and the cylinders 3a,
Pressure fluid is supplied to and discharged from 3b, 3c, and 3d to perform roll control of the vehicle body.

Note that, step and step are feedback control, and to explain this, the actual vehicle height is detected from the vehicle height sensor 10a, 10b, 10c, 10d in step, and the detected vehicle height is a spring due to unevenness of the road surface. Since there is an influence of the lower vibration, the averaging processing means performs integration for a certain period of time to perform averaging. Then, in a step, the averaging-processed vehicle height and the pressure fluid of the target supply / discharge amount are transferred to the cylinders 3a, 3b,
Expected vehicle height when supplied to and discharged from 3c and 3d (target vehicle height)
Is compared, and if they do not match, the process returns to the step again and the required pressure fluid is supplied to and discharged from each cylinder 3a, 3b, 3c, 3d, and the actual vehicle height and the target vehicle height match. .

Next, the steering direction determination means in the steps of the above flow chart
A subroutine for determination by 21 is shown in FIG. 8 and will be described.

In the step, it is determined whether the current steering wheel position is on the left of the front steering wheel position (the position of the steering wheel before the current steering), that is, whether the steering wheel is rotated to the left. This can be determined by the ON / OFF state of the signals A and B from the steering sensor. Then, if it is determined in step that the steering wheel is rotated to the left (YES), the current steering is determined to be leftward steering in step.
Further, in the step where it is determined that the handle is not rotated to the left (NO), it is determined whether the current handle position is to the right of the front handle position, that is, whether the handle is rotated to the right. When it is determined that the steering wheel has been rotated to the right in step (YES), the left steering determination is canceled in step and the process proceeds to step. In step, the steering wheel is not rotated to the right, that is, the steering wheel is rotated to the left or right. If it is determined that neither of them is rotated, the process directly proceeds to the step.

In the step, it is determined whether the current steering wheel position is on the right side of the center (position where the steering angle is 0). This can be determined by whether the added steering angle is positive or negative. If it is determined in step that the steering wheel position is to the right of the center (YES), the process proceeds to step and it is determined whether leftward steering determination is currently performed. And
Leftward steering judgment is currently made in step (YES)
If it is determined that the steering is in the return direction, it is determined that the steering is in the return direction, and if it is determined that the steering is not in the left direction (NO), the steering is in the turning direction.

If it is determined in step that the current steering wheel position is not on the right side of the center (NO), the process proceeds to step and it is determined whether the current steering wheel position is on the left side of the center. When it is determined in step that the steering wheel position is on the left side of the center (YES), the process proceeds to step and it is determined whether the leftward steering determination is currently performed. If it is determined that the leftward steering determination is currently made (YES) in the step, it is determined that the steering is in the turning direction, and the leftward steering determination is not made (NO) in the step. In the step, it is determined that the steering is in the return direction.

Furthermore, if it is determined in the step that the current steering wheel position is not on the left side of the center, that is, if the steering wheel is in the center, the steering wheel always returns to the previous steering wheel position. To be judged.

In this way, it is determined whether steering in the turning direction or steering in the returning direction has been performed. Then, in step, the current handle position is set to the front handle position and the process returns to the main routine.

When suspension control is performed using the control device 9 having the above-described configuration, when the steering wheel is steered in the turning direction, the valve opening time for vehicle body posture control calculated from the lateral acceleration estimated from the vehicle speed and the steering angle is 2 times. The pressure in the cylinder rises or falls because the pressure fluid in the cylinder is increased or decreased because the pressure fluid is supplied to and discharged from the cylinder based on the reset valve opening time. Excretion is not completely eliminated. Furthermore, during steering in the return direction, the valve opening time is reset to 1/2, and pressure fluid is supplied to and discharged from the cylinder based on the reset valve opening time. It is possible to prevent the pressure fluid from being supplied and discharged in excess of the discharge amount.

Therefore, the pressure fluid of the target supply / discharge amount can be supplied to / discharged from the cylinder without being influenced by the cylinder internal pressure, so that the roll control for reliably stabilizing the posture of the vehicle can be performed.

Next, one specific example of the supply / discharge control of the pressure fluid by the suspension control device of the present embodiment will be described in comparison with the supply / discharge control by the conventional suspension control device.

FIG. 9A shows the actual fluctuation of the steering angle.
The figure shows the case where the steering wheel is turned to the left from straight running and steering is performed in the turning direction, and the steering wheel is returned midway to perform the steering in the returning direction.

In the conventional control in such a traveling state, as shown in FIGS. 10 (a), (b), and (c), the steering angle is θ ₁ rotation in both the turning steering and the returning steering. Each time the valve is opened, the supply / discharge valves 8a, 8b, 8c, 8d are opened for the valve opening time T (v).
The roll angle becomes as shown in Fig. 2D, and the vehicle body cannot be sufficiently stabilized.

On the other hand, in the control of this embodiment, as shown in FIG.
As shown in (c), during steering in the turning direction, the valve opening time is reset to 2 · T (v), and during that time the supply / discharge valves 8a, 8b, 8c, 8d are set.
Valve is opened, and the valve opening time is 1/2 when steering in the return direction.
Since T (v) is reset and the supply / discharge valves 8a, 8b, 8c, 8d are opened at that time, the control is properly performed according to the rolling of the vehicle, and the roll angle is adjusted as shown in FIG. 9 (d). It is possible to make almost no fluctuations in.

In the present embodiment, the valve opening time T (v) set by the logical operation means 20 is doubled in the case of the turning steering, and the valve opening time is halved in the case of the returning steering. However, the present invention is not limited to this, and the cylinder internal pressure is estimated from the estimated value of the lateral acceleration,
The valve opening time may be reset so that the target supply / discharge amount of pressure fluid can be supplied / discharged according to the cylinder internal pressure. In this case, fine control can be performed and better roll control can be performed.

Further, in the steering direction determination subroutine shown in FIG. 8, when it is determined to be (NO) in step and the steering wheel is not rotated to the left or right, the steering stop determination is immediately performed in step as shown by the broken line. You may make it jump to a step. And in this case,
By using the valve opening time T (v) set by the logical operation means 20 in the step as it is without resetting the valve opening time of the supply / discharge valve in the step of FIG. It is also possible to do.
When the steering wheel is subsequently rotated, the steering stop determination shown in FIG. 8 may be canceled by, for example, providing a steering stop determination cancellation step immediately before the step.

Further, in the present embodiment, the valve opening time T (v) once set by the logical operation means 20 is configured to be reset by the resetting means 22 in accordance with the turning steering and the returning steering. Not limited to this, the logical operation means 20 and the resetting means 22 are configured as one logical operation means, and steering direction determination means
Based on the determination of 21, it is possible to individually calculate the valve opening times corresponding to the case of the turning steering and the case of the returning steering.

In addition, in each of the above-described embodiments, the supply / discharge valves 8a, 8b, 8c, 8d are configured as the on / off valves, and therefore, the supply / discharge amount of the pressure fluid is described as being controlled by the valve opening time, but not limited to this. If the supply / discharge valves 8a, 8b, 8c, 8d are configured as electromagnetic proportional control valves, the valve opening amount can be changed according to the magnitude of the current, and the supply / discharge amount of the pressure fluid can be controlled. In the above, the valve opening amount may be controlled, and both the valve opening time and the valve opening amount may be controlled.

(Effect of the Invention) As described in detail above, in the present invention, the valve opening time or valve opening amount of the valve means set from the vehicle speed and the steering angle is
In the case of steering in the turning direction, the valve opening time is set long or the valve opening amount is set large, and in the case of the return steering, the valve opening time is set short or the valve opening amount is set small, and the set valve opening is set. Since the pressure fluid is supplied to and discharged from the cylinder based on the time or the valve opening amount, the supply and discharge amount of the pressure fluid set by the internal pressure of the cylinder cannot be accurately supplied and discharged.

Then, by supplying / discharging the set appropriate amount of pressure fluid to / from the cylinder, optimal posture control of the vehicle can be performed,
The maneuverability and riding comfort can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an example of a control device provided in a suspension control device of the present invention, FIG. 2 is a diagram showing an entire configuration of an example of a suspension control device of the present invention, and FIG. FIG. 4 is a perspective view showing an example of a steering angle sensor used in the invention, FIG. 4 is a front view of the steering angle sensor shown in FIG. 3, and FIG. 5 is a configuration of the steering angle sensor shown in FIG. 6 is a perspective view, FIG. 6 is a diagram showing an example of a signal output from the steering angle sensor shown in FIG. 3, FIG. 7 is a flow chart diagram of control by the control device shown in FIG. FIG. 9 is a flowchart of the steering direction determination by the steering direction determination means of the control device shown in FIG. 1, and FIG. 9 is a pressure fluid to the left and right cylinders by the control device of the present invention when steering to the left. Showing the time variation of the roll angle that occurs in the supply and discharge of the vehicle and the vehicle FIG. 10 is a diagram showing the time-dependent change in the roll angle caused by the supply and discharge of pressure fluid to the left and right cylinders and the vehicle caused by the conventional control device when steering to the left, and FIG. 11 is the steering to the left. It is a figure which shows the state of the internal pressure of the cylinder on either side when doing. 3a, 3b, 3c, 3d ...... Cylinder 7 ...... Supply source 8a, 8b, 8c, 8d ...... Supply / discharge valve (valve means) 9 ...... Control device 20 ...... Logical operation means 21 ...... Steering direction determination means 22 ...... Resetting means

Claims (1)

(57) [Claims] 1. A pressure fluid supply source is connected to a cylinder of a suspension unit interposed between a vehicle body side and a wheel side, and valve means is operated on the basis of a signal from a control device to apply pressure fluid to the cylinder. In the suspension control device capable of controlling the attitude of the vehicle body by supplying and discharging the vehicle, the controller controls the supply and discharge of the pressure fluid to and from the cylinder so as to suppress the attitude change of the vehicle body expected from the vehicle speed and the steering angle. Logical operation means for setting the valve opening time or valve opening amount of the valve means to set the exhaust amount, and the steering direction for determining whether the current steering is the turning steering or the returning steering with respect to the steering angle when going straight. When the determining means and the steering direction determining means determine that the steering is in the turning direction, the valve opening time of the valve means is set to be long or the valve opening amount is set to be large, and when the steering direction determining means determines the return steering. Suspension control apparatus characterized by comprising: a resetting means for setting a small short or valve lift valve opening time, a is.