JP2008230466A - Suspension control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce energy consumption by a simple structure in a suspension control device. <P>SOLUTION: Left and right suspension units 2 of the vehicle are connected to each other through a dual-direction hydraulic pump 3. A motor 4 for driving the dual-direction hydraulic pump 3 is controlled by a controller 6 based on the vehicle state detected by a lateral acceleration sensor 11, a steering angle sensor 12 and a vehicle height sensor 17, and rolling of the vehicle body at turning is suppressed by transferring an oil liquid between the left and right suspension units 2. At this time, in the controller 6, high-pass filter processing is performed relative to a control signal based on detection of the vehicle height sensor 17. Thereby, the control signal of low frequency can be cut relative to steady inclination of the vehicle body due to variation of loading load caused by getting in/out of an occupant, unnecessary attitude control is prevented from being performed and energy consumption can be reduced. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a suspension control device that is mounted on a vehicle such as an automobile and controls the posture of the vehicle body.

For example, as described in Patent Document 1, a hydraulic cylinder of a suspension unit interposed between a vehicle body side and a wheel side includes a pump, an accumulator, and the like via supply / discharge means such as a supply / discharge switching valve. Based on parameters such as vertical and lateral accelerations of the vehicle body detected by various sensors connected to a hydraulic source, the controller operates the supply / discharge means to supply / discharge oil to / from the hydraulic cylinder according to the running state of the vehicle Thus, a so-called active suspension control device is known in which the posture control of the vehicle body is performed. According to the active suspension device, it is possible to optimally control the posture of the vehicle body according to the traveling state of the vehicle, and it is possible to achieve both a high level of comfort and handling stability.
JP-A-2-246816

  However, the above-described active suspension device has the following problems. Since the active suspension device requires a complicated hydraulic system, the manufacturing cost is high, and energy consumption increases because the active suspension device is always operated while the vehicle is running. Therefore, there has been a demand for a suspension control device that can effectively control the posture of a vehicle body with a simpler structure and consumes less energy.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a suspension control device that can reduce energy consumption with a simple structure.

In order to solve the above problems, an invention according to claim 1 is based on attitude control means for controlling the attitude of a vehicle body by an actuator, detection means for detecting a vehicle state including a vehicle height, and detection by the detection means. A suspension control device comprising a controller that outputs a control signal to operate the posture control means to execute the posture control of the vehicle body,
The controller performs high-pass filter processing on a control signal based on vehicle height.
According to a second aspect of the present invention, in the suspension control device according to the first aspect, the controller determines whether or not the vehicle is in a steady circular turn based on the detection by the detection means, and is in a steady circular turn. When it is determined that, the time constant of the high-pass filter is increased.
According to a third aspect of the present invention, in the configuration of the first or second aspect, the controller sets a standard vehicle height that serves as a reference for detection of the vehicle height by the detection means, and the vehicle height detected by the detection means. When the vehicle constantly changes, the vehicle height is set as the standard vehicle height.

According to the suspension control device of the first aspect of the present invention, when the vehicle height changes steadily due to changes in the loading load caused by passengers getting on and off, loading and unloading of luggage, etc. Since the control signal is cut by the high-pass filter, unnecessary posture control can be prevented and energy consumption can be reduced.
According to the suspension control device of the second aspect of the present invention, the cut-off frequency of the high-pass filter is lowered during steady circle turning so that the control signal based on the vehicle height change due to the steady circle turning passes through the high-pass filter. Thus, appropriate posture control can be performed.
According to the suspension control device of the third aspect of the present invention, when the vehicle height changes steadily due to a change in the load caused by the passenger getting on and off, loading or unloading of the load, the vehicle height is detected as the standard vehicle height. Therefore, unnecessary posture control is prevented from being performed due to steady changes in the vehicle height, and energy consumption can be reduced.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a schematic configuration of a suspension control device 1 according to the present embodiment mounted on an automobile. As shown in FIG. 1, the suspension control device 1 includes both a suspension unit 2 (posture control means) provided on each of the front and rear wheels and the left and right suspension units 2 of the front and rear wheels. A directional hydraulic pump 3 (attitude control means), a motor 4 (actuator) and motor driver 5 that drive the bidirectional hydraulic pump 3, and a controller 6 that controls the motor driver 5 are provided.

  The suspension unit 2 includes a hydraulic cylinder 7 and a suspension spring 8 interposed between a wheel side (under spring) and a vehicle body side (on spring) of the suspension device, and an accumulator 9 connected to the hydraulic cylinder 7. ing. The hydraulic cylinder 7 is a slidably fitted piston having a piston rod connected to a cylinder filled with oil liquid, and the oil liquid is supplied to and discharged from the cylinder through an oil passage provided in the piston rod. By doing so, the piston rod can be expanded and contracted. Further, the piston portion is provided with a damping force generation mechanism including an orifice, a disk valve, and the like that generate a damping force by controlling the flow of the oil liquid generated by the expansion and contraction of the piston rod. The hydraulic cylinder 7 is connected to an accumulator 9, a spring force is applied to the expansion and contraction of the piston rod by the accumulated pressure of the accumulator 9, and the vehicle body is supported by the spring force and the spring force of the suspension spring 8.

  The bidirectional hydraulic pump 3 is capable of discharging in both directions according to the rotation direction of the motor 4, and is connected between the hydraulic cylinders 7 of the left and right suspension units 2, and according to the rotation direction of the motor 4. Thus, the oil liquid can be transferred from one to the other and from the other to the other between the hydraulic cylinders 7 of the left and right suspension units 2.

  The motor 4 is a servo motor whose rotation direction and number of rotations (rotation speed) can be controlled by a control current from the motor driver 5, and drives the bidirectional hydraulic pump 3 according to the control current from the motor driver 5.

  The controller 6 is a microprocessor-based control circuit, and includes a pressure sensor 10 that detects the pressure of the hydraulic cylinder 7 of each wheel (accumulated pressure of the accumulator 9), a lateral acceleration sensor 11 that detects the lateral acceleration of the vehicle body, and a steering wheel. A steering angle sensor 12 for detecting a steering angle, a vehicle speed sensor 13, a longitudinal acceleration sensor 14 for detecting acceleration in the longitudinal direction of the vehicle, a brake switch 15 for detecting brake operation, a throttle opening sensor 16 for detecting throttle opening, and A detection signal from a sensor provided in each part of the vehicle, such as a vehicle height sensor 17 for detecting the vehicle height for each wheel, is input, these input signals are processed according to a predetermined logic rule, and a control signal is sent to the motor driver 5. The motor 4 is controlled by outputting.

Next, vehicle body roll control by the controller 6 will be described.
When the vehicle turns, the vehicle body rolls (tilts) outwardly around the axis in the front-rear direction due to the centrifugal force acting on the vehicle body and the lateral force due to the frictional force between the wheels and the ground. On the other hand, the controller 6 is based on the vehicle information such as the lateral acceleration, the steering angle, and the vehicle speed detected by the pressure sensor 10, the lateral acceleration sensor 11, the steering angle sensor 12, the vehicle speed sensor 13, and the vehicle height sensor 17. Calculate the running state. Then, a control signal is output to the motor driver 5 according to the running state, the rotation of the motor 4 is controlled, and the bidirectional hydraulic pump 3 causes the suspension unit 2 outside the turning from the hydraulic cylinder 7 and the accumulator 9 of the suspension unit 2 inside the turning. The oil liquid is transferred to the hydraulic cylinder 7 and the accumulator 9. Thereby, the roll of the vehicle body at the time of turning can be suppressed and steering stability can be improved.

  Next, processing by the controller 6 will be described in more detail with reference to FIGS. As shown in FIG. 2, the controller 6 receives a signal S indicating the running state of the vehicle by the above-described various sensors, A / D converts these signals, and inputs them to the roll control block B. 4 target flow rate is calculated. The calculated target flow rate is converted into the target rotation number of the motor 4 using the flow rate-rotation number map (representing the relationship between the flow rate and the rotation number of the bidirectional hydraulic pump 3) shown in FIG. Output to.

  As shown in FIG. 4, the roll control block B includes a lateral acceleration control unit B1, a pressure control unit B2, and a vehicle height control unit B3. The lateral acceleration control unit B1 calculates a target flow rate based on the output signal of the lateral acceleration sensor 11. The pressure control unit B2 is configured to output the hydraulic cylinders 7 of the left and right wheels based on the output signal of the pressure sensor 10 (differential pressure of the left and right hydraulic cylinders 7) provided in the hydraulic cylinder 7 of each wheel and the output signal of the lateral acceleration sensor 11. The target differential pressure is calculated. The vehicle height controller B3 calculates a roll component of the vehicle body from the difference between the left and right vehicle heights based on the output signal of the vehicle height sensor 13 provided on each wheel, and outputs a control signal.

  The vehicle height calculation control unit B3 is provided with a high-pass filter 18 that cuts a predetermined low-frequency component with respect to an output signal based on the calculated roll component (left and right vehicle height difference). The cut-off frequency of the high-pass filter 18 cuts only components of steady vehicle height changes caused by changes in the loading load such as passengers getting on and off, loading and unloading, refueling, etc., and turning by steering in a normal driving state It is set sufficiently low so as not to affect the roll component generated by (running on curved roads, curved roads, turning left and right, U-turns, changing lanes, etc.).

  As a result, when the vehicle height changes steadily (roll) due to a change in the loaded load, the control signal based on the roll component is cut by the high-pass filter 18, so an unnecessary roll relative to the steady body roll due to the loaded load is removed. Since control is not executed, the power consumption of the motor 4 can be reduced.

Next, the adjustment of the time constant of the high-pass filter 18 will be described with reference to FIGS.
When the vehicle is turning at a constant speed and a constant radius (steady circle turning), a constant lateral acceleration is generated in the vehicle body and a constant roll angle is maintained. At this time, if this state is regarded as a steady vehicle height change and the control signal is cut by the high-pass filter 18, appropriate roll control is not executed.

  Therefore, the controller 6 is provided with a time constant adjusting unit 19 as shown in FIG. The time constant adjustment unit 19 includes a steady circle turning determination unit 20 and a time constant setting unit 21. The steady circle turning determination unit 20 determines whether the vehicle is in a steady circle turning state based on the change in lateral acceleration (lateral acceleration differential value) detected by the lateral acceleration sensor 11 and the steering angle (steering angle) detected by the steering angle sensor 12. It is determined whether or not.

  Determination of steady circle turning by the steady circle turning determination unit 20 will be described with reference to the flowchart of FIG. Referring to FIG. 7, in step S1, it is determined whether or not the absolute value of the steering angle detected by steering angle sensor 12 is larger than the set value. If so, it is determined in step S4 that the steady circle is not turning, and the routine is terminated. In step S2, it is determined whether or not the state where the absolute value of the differential value of the lateral acceleration detected by the lateral acceleration sensor 11 is smaller than the set value has continued for a predetermined time t seconds or longer. If so, the process proceeds to step S3. If it is determined in step S4 that it is not in a steady circle, the process proceeds to step S4, where it is determined that it is not in a steady circle, and the routine is terminated.

  The time constant setting unit 21 sets the cutoff frequency (time constant) of the high-pass filter 18 based on the determination result by the steady circle turning determination unit 20.

  The setting of the time constant by the time constant setting unit 21 will be described with reference to the flowchart of FIG. Referring to FIG. 8, in step S1, the determination result by steady circle turning determination unit 20 is determined. If it is determined that steady circle turning is in progress, the process proceeds to step S2 where high-pass filter 18 is set as a through-pass. If it is determined that the vehicle is not turning, the routine proceeds to step S3, where the cutoff frequency of the high-pass filter 18 is set to a predetermined set value, and the routine is terminated. In step S2, instead of using the high-pass filter 18 as a through-pass, the cut-off frequency of the high-pass filter 18 is increased (time constant is increased), and a control signal based on the roll component due to the steady circular turn passes through the high-pass filter 18. You may make it do.

  As a result, when the vehicle is in a steady circular turn, the control signal based on the roll component thereby can pass through the high-pass filter 18, so that the vehicle height sensor 13 detects the steady circular turn. Appropriate roll control can be executed based on the calculated roll component, and steering stability can be improved.

  In addition to the above, other means may be used as the determination means for the steady circle turning as long as it can determine whether the steady circle turning is in progress, such as the yaw rate and the wheel speed.

  As shown in FIG. 6, the suspension control device 1 is provided with a door switch 22 for detecting the opening / closing of the door and a trunk switch 23 for detecting the opening / closing of the trunk. A portion 24 is provided.

  The standard vehicle height calculation unit 24 monitors occupant getting on and off and loading / unloading of the passenger based on the outputs of the vehicle height sensor 13, the door switch 22 and the trunk switch 23, and sets the vehicle height after the completion as a standard vehicle height. , Roll component calculation based on this standard vehicle height

The calculation flow of the standard vehicle height by the standard vehicle height calculation unit 24 will be described with reference to FIG.
Referring to FIG. 9, in step S1, the trunk switch 23 determines whether the trunk is open or closed. If it is closed, the process proceeds to step S2, and if it is open, the trunk open flag is set and the routine is terminated. In step 2, the door switch 22 determines whether the door is open or closed. If the door is closed, the process proceeds to step S3. If the door is open, the door is opened and the routine is terminated. In step S3, based on the trunk open flag and the door open flag, it is determined whether or not the door or the trunk has been opened in the previous routine, and if either is open, the process proceeds to step S4 and both are closed. If so, the routine is terminated. In step S4, the vehicle height at that time is set to the standard vehicle height, and the process proceeds to step S5. In step S5, the high-pass filter 18 is initialized and the routine is terminated.

  In this way, it is possible to determine whether passengers are getting on and off and loading / unloading of luggage based on the opening and closing of doors and trunks. The height is set as the standard vehicle height, and the change in the vehicle height is detected based on the standard vehicle height to calculate the roll component. As a result, unnecessary roll control can be prevented from being executed with respect to a steady inclination of the vehicle body due to a change in the loaded load caused by the passenger getting on and off and the loading and unloading of the load, and the power consumption of the motor 4 is reduced. can do. At this time, after setting the standard vehicle height (step S4 in FIG. 9), the high-pass filter 18 is initialized (step S5 in FIG. 9), so that the vehicle height control is performed by a sudden change in the output signal of the vehicle height sensor 13. A sudden change in the control signal from the part B3 can be suppressed.

  Next, a modification of the standard vehicle height calculation unit 24 will be described with reference to FIG. In this modification, the standard vehicle height calculation unit 24 uses a low-pass filter for the output signal of the vehicle height sensor 13 and the vehicle speed sensor 13 instead of the door switch 22 and the trunk switch 23 to monitor the change in vehicle height and the vehicle speed. When there is no change in vehicle height over a predetermined time in a state where the vehicle speed is zero, the vehicle height at that time is set to the standard vehicle height.

  The calculation of the standard vehicle height by the standard vehicle height calculation unit of this modification will be described with reference to the flowchart of FIG. Referring to FIG. 10, in step S1, the output signal of vehicle height sensor 13 is received through a low-pass filter, and the process proceeds to step S2. In step S2, it is determined whether or not there is no change in vehicle height over a predetermined time in a state where the vehicle speed is zero. If the vehicle speed is zero and there is no change in vehicle height, the process proceeds to step S3. To do. In step S3, the vehicle height at that time is set to the standard vehicle height, and the process proceeds to step S4. In step S4, the high-pass filter 18 is initialized and the routine is terminated.

  In this way, the standard vehicle height is set and updated based on whether or not the vehicle height changes while the vehicle is stopped (vehicle speed is zero), and the roll component is calculated by detecting the vehicle height change based on the standard vehicle height. . As a result, unnecessary roll control can be prevented from being executed with respect to a steady inclination of the vehicle body due to a change in the loaded load caused by passengers getting on and off, loading and unloading of luggage, and the power consumption of the motor 4 is reduced. be able to. At this time, after setting the standard vehicle height (step S3 in FIG. 10), the high-pass filter 18 is initialized (step S4 in FIG. 10), so that the vehicle height control is performed by a sudden change in the output signal of the vehicle height sensor 13. A sudden change in the control signal from the part B3 can be suppressed.

  In the above embodiment, a suspension control device that performs roll control is described as an example. However, in the suspension control device, the front and rear suspension units 2 are replaced with the bidirectional hydraulic pump 3 instead of the left and right suspension units 2. The present invention can be similarly applied to a suspension control device that is connected to each other via the vehicle and performs pitch control of the vehicle body based on longitudinal acceleration, vehicle height change, and the like.

  In the above-described embodiment, the suspension control device that performs vehicle body posture control by the hydraulic system is described. However, roll control is performed by using an air suspension control device that performs vehicle body posture control by air pressure, an electric actuator, or the like. The present invention can be similarly applied to other suspension control devices that control the posture of the vehicle body using an actuator, such as an electric stabilizer.

1 is a block diagram showing a schematic configuration of a suspension control device according to an embodiment of the present invention. It is a figure which shows the control block of the controller of the suspension control apparatus shown in FIG. It is a figure which shows the flow volume-rotation speed map of the bidirectional | two-way hydraulic pump memorize | stored in the controller of the suspension control apparatus shown in FIG. It is a block diagram which shows the process performed by the roll control block of the controller of the suspension control apparatus shown in FIG. It is a block diagram which shows the time constant adjustment part of the controller 6 of the suspension control apparatus shown in FIG. The block diagram which shows the standard vehicle height calculating part of the controller of the suspension control apparatus shown in FIG. It is a figure which shows the determination flow of the steady circle turning by the steady circle turning determination part of the controller 6 of the suspension control apparatus shown in FIG. It is a figure which shows the setting flow of the time constant by the time constant setting part of the controller 6 of the suspension control apparatus shown in FIG. It is a figure which shows the calculation flow of the standard vehicle height by the standard vehicle height calculating part of the controller 6 of the suspension control apparatus shown in FIG. It is a figure which shows the calculation flow of the standard vehicle height by the modification of the standard vehicle height calculation part of the controller 6 of the suspension control apparatus shown in FIG.

Explanation of symbols

  1 suspension control device, 2 suspension unit, 3 bidirectional hydraulic pump (attitude control means), 4 motor (actuator), 6 controller, 17 vehicle height sensor, 18 high-pass filter

Claims (3)

Attitude control means for controlling the attitude of the vehicle body by means of an actuator; detection means for detecting a vehicle state including vehicle height; and output of a control signal based on detection of the detection means to operate the attitude control means to A suspension control device including a controller for performing attitude control of
The suspension control device, wherein the controller performs high-pass filter processing on a control signal based on vehicle height. The controller determines whether or not the vehicle is in a steady circular turn based on the detection of the detection means, and when determining that the vehicle is in a steady circular turn, increases the time constant of the high-pass filter; The suspension control device according to claim 1. The controller sets a standard vehicle height that serves as a reference for detecting the vehicle height by the detecting means, and sets the vehicle height as the standard vehicle height when the vehicle height detected by the detecting means changes constantly. The suspension control apparatus according to claim 1, wherein the suspension control apparatus is a suspension control apparatus.

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