JP2020132122A - Suspension device and method of controlling the same - Google Patents

Abstract

To provide a suspension device that improves response of damping force of an ERF damper.SOLUTION: When damping force is changed from soft characteristics to hard characteristics, an overshoot control mode in which a voltage having an overshoot voltage value V3 larger than a target voltage value V2 is applied to an electroviscous fluid, and after the applied voltage is held at the overshoot voltage value V3 for a certain time, a voltage having the target voltage value V2 is applied is performed so as to improve response of damping force of an ERF damper.SELECTED DRAWING: Figure 3

Description

The present invention relates to a suspension device provided in a vehicle such as an automobile and a control method thereof.

Patent Document 1 discloses a cylinder device using an electric viscous fluid (ERF: Electric Rheological Fluid) as a working fluid, a so-called ERF damper.

International Publication No. 2017/038577

In the suspension device equipped with the ERF damper, when the damping force is switched from the soft characteristic to the hard characteristic, the voltage value applied to the electrorheological fluid is changed from, for example, 0 volt to several kilovolts. Here, when the time-series waveform of the applied voltage and the time-series waveform of the damping force are superimposed, the time when the applied voltage reaches the voltage value at which the target damping force is generated (hereinafter referred to as "target voltage value") and There is a time lag of several tens of milliseconds between the time when the ERF damper generates the target damping force. Due to this time lag, the response delay of the damping force may occur, and the riding comfort and steering stability of the vehicle may deteriorate.

An object of the present invention is to provide a suspension device having improved responsiveness of damping force of an ERF damper and a control method thereof.

The suspension device of the present invention is a suspension device that generates a damping force according to a voltage value applied to an electrorheological fluid, and when the damping force is changed, a target damping force is generated in the electrorheological fluid. It is characterized in that a voltage value larger than the target voltage value is applied, and then the target voltage value is applied.
The control method of the suspension device of the present invention is a control method of the suspension device that generates a damping force according to the voltage value applied to the electrorheological fluid, and the electrorheological viscosity when the vehicle is in a traveling state or a traveling state. When a constant baseline voltage value is applied to the fluid to change the damping force, the electrorheological fluid is subjected to a voltage value larger than the target voltage value for generating the target damping force, and then the target It is characterized in that a voltage value is applied.

According to the present invention, the responsiveness of the damping force of the ERF damper in the suspension device can be improved.

It is a conceptual diagram of the suspension device in this embodiment. It is a block diagram of the suspension control in this embodiment. It is explanatory drawing of the suspension control in this embodiment, and is the figure which shows the time series waveform of the applied voltage in the overshoot control mode. It is explanatory drawing of the suspension control in this embodiment, and is the figure which shows the time-series waveform of the applied voltage in the baseline offset control mode. It is explanatory drawing of the suspension control in this embodiment, and is the figure which shows the time series waveform of the applied voltage in the control mode which combined the overshoot control mode and the baseline offset control mode. It is explanatory drawing of the suspension control in this embodiment, and is the figure which shows the time-series waveform of the applied voltage when a running mode is switched from a sport mode to an eco-mode. It is explanatory drawing of the conventional suspension control, and is the figure which superimposes the time-series waveform of an applied voltage, and the time-series waveform of a damping force. It is explanatory drawing of the suspension control of this embodiment, and is the figure which superimposes the time-series waveform of the applied voltage in the overshoot control mode, and the time-series waveform of a damping force. It is explanatory drawing of the suspension control of this embodiment, and is the figure which superimposes the time-series waveform of the applied voltage in the baseline offset control mode, and the time-series waveform of a damping force.

An embodiment of the present invention will be described with reference to the attached figure.
Here, the suspension device 1 of a four-wheeled vehicle is illustrated. FIG. 1 shows a conceptual diagram of the suspension device 1. Note that FIG. 1 shows a suspension device 1 corresponding to one of the four wheels 3. Further, the basic structure of the ERF damper 5 in the suspension device 1 is, for example, the same as the cylinder device disclosed in International Publication No. 2017/038577. Therefore, a detailed description of the ERF damper 5 will be omitted for the purpose of simplifying the description of the specification.

Referring to FIG. 1, the suspension device 1 has a suspension spring 4 and an ERF damper 5 interposed between the vehicle body 2 and the wheels 3. The tire 3A is mounted on the wheel 3. The ERF damper 5 is a damping force adjusting type fluid shock absorber that uses an electrorheological fluid as a working fluid. The electrorheological fluid (ERF) is composed of a base oil made of, for example, silicon oil and fine particles dispersed in the base oil, and its viscosity (flow resistance) changes according to the applied voltage. The controller 21 (ECU: Electronic Control Unit) controls the voltage value applied to the electrorheological fluid, and continuously or stepwise changes the damping force generated by the ERF damper 5 from the soft characteristic to the hard characteristic.

The positive electrode of the battery 6 is connected to an intermediate cylinder (not shown) which is an electrode on the positive electrode side of the ERF damper 5 via a high voltage driver 7 provided with a booster circuit. On the other hand, the negative electrode (ground) of the battery 6 is connected to the inner cylinder (not shown) of the ERF damper 5 via the high voltage driver 7. The high voltage driver 7 boosts the DC voltage (Batt voltage) output from the battery 6 based on the high voltage command output from the controller 21 and outputs it to the ERF damper 5 (high voltage output). Further, the high voltage driver 7 monitors the voltage value (Batt voltage) output from the battery 6 and outputs the monitor signal of the voltage value to the controller 21 as the value of the Batt voltage monitor.

The suspension device 1 has a traveling state detection unit 11 that detects the traveling state of the vehicle. The controller 21 controls the voltage value applied to the electrorheological fluid based on the detection result of the traveling state detection unit 11. The controller 21 executes a high voltage command calculation using the detection result of the traveling state detection unit 11 and calculates a high voltage command to be output to the high voltage driver 7. The high voltage driver 7 outputs a high voltage to the ERF damper 5 based on the high voltage command output from the controller 21. As a result, a voltage (voltage value) corresponding to the output (high voltage output) of the high voltage driver 7 is applied to the electrorheological fluid flowing through the flow path between the intermediate cylinder and the inner cylinder of the ERF damper 5. As a result, the viscosity (property) of the electrorheological fluid changes according to the potential difference (potential gradient) between the intermediate cylinder and the inner cylinder. As a result, the ERF damper 5 generates a damping force according to the voltage value applied to the electrorheological fluid.

The driving state detection unit 11 includes sensors for detecting the front / rear, left / right, yaw position, speed, and acceleration, sensors for detecting the driver's operation amount such as accelerator, brake, and steering, a camera, radar, GPS, and the like. It suffices if the vehicle can detect the running state of the vehicle, such as an external sensor. Further, the traveling state detection unit 11 may be provided exclusively for the suspension, or may be obtained from the CAN (Controller Area Network) of the vehicle. Further, the traveling state detection unit 11 detects which mode the traveling mode (for example, "eco mode" and "sports mode") is set.

FIG. 2 shows a block diagram of damper control in the suspension device 1.
As shown in FIG. 2, the controller 21 has a control mode selection unit 22 and a control command unit 23. In the present embodiment, the control mode selection unit 22 has a basic control mode of an overshoot control mode and a baseline offset control mode. The control mode selection unit 22 selects the control mode based on the detection result of the traveling state detection unit 11. The control command unit 23 calculates a control command value (high voltage command) according to the control mode selected by the control mode selection unit 22, and outputs the calculation result to the high voltage driver 7.

3 to 5 show voltage values applied to the electrorheological fluid in each control mode of the overshoot control mode, the baseline offset control mode, and the control mode in which the overshoot control mode and the baseline offset control mode are combined. A time-series waveform, in other words, a time-series waveform of a control command value output from the control command unit 23 is shown. The unit of the voltage value on the vertical axis is "kilovolt", and the unit of time on the horizontal axis is "millisecond".

In the overshoot control mode, the controller 21 applies an overshoot voltage value V3 larger than the target voltage value V2 that generates the target damping force to the electrorheological fluid when the damping force generated by the ERF damper 5 is changed. After that, the target voltage value V2 is applied. Referring to FIG. 3, in the overshoot control mode, the controller 21 applies a voltage value V0 to the electrorheological fluid from time T0 to time T1 (hereinafter referred to as “time T0−T1”). The voltage value V0 in this embodiment is "0 volt". In other words, the baseline voltage value in the overshoot control mode is "0 volt". When the applied voltage is the voltage value V0 (baseline voltage value), the ERF damper 5 generates a soft characteristic damping force.

The controller 21 applies an overshoot voltage value V3 to the electrorheological fluid when the damping force is changed from the soft characteristic to the hard characteristic at time T1. The controller 21 maintains the applied voltage at the overshoot voltage value V3 during the time T1 to T2 (hereinafter referred to as “time T1-T2”), and at the time T2, the applied voltage is changed from the overshoot voltage value V3 to the target voltage. It is lowered to the value V2, and then the applied voltage is maintained at the target voltage value V2.

Here, the overshoot voltage value V3 is a voltage value at which the damping force of the ERF damper 5 shows a tendency of overshoot when applied to an electrorheological fluid. Further, the time T1-T2 is set to a time (for example, "several milliseconds") at which the damping force of the ERF damper 5 does not actually overshoot when the overshoot voltage value V3 is applied to the electrorheological fluid. To. That is, the overshoot voltage value V3 in the present embodiment is not applied to the electrorheological fluid for the purpose of overshooting the damping force of the ERF damper 5, but is for improving the responsiveness of the damping force of the ERF damper 5. , It is applied to the electrorheological fluid prior to the target voltage value V2.

In the baseline offset control mode, the controller 21 applies a constant offset voltage value V1 to the electrorheological fluid when it determines that the vehicle is in a travelable state or in a traveling state. Referring to FIG. 4, in the baseline offset control mode, when the controller 21 detects that the vehicle is in a travelable state or a traveling state based on the detection result of the traveling state detecting unit 11 at time T0, it becomes an electrorheological fluid. The offset voltage value V1 is applied. The controller 21 maintains the applied voltage at the offset voltage value V1 while the vehicle is in a traveling state or a traveling state. When the damping force of the ERF damper 5 is changed at time T1, the controller 21 raises the applied voltage from the offset voltage value V1 to the target voltage value V2, and then maintains the applied voltage at the target voltage value V2.

Here, in the electrorheological fluid, the electrorheological effect is exhibited by the atoms and ions in the fine particles dispersed in the base oil being displaced by the applied voltage and the fine particles being polarized. When the applied voltage is gradually increased from 0 volt due to the mechanism by which atoms and ions move and polarization occurs, the properties change significantly at a certain voltage value. In other words, the ERF damper 5 has a range of voltage values in which the damping force does not change significantly when the voltage value applied to the electrorheological fluid is gradually increased from 0 volt, but when the applied voltage reaches a certain voltage value, it is attenuated. Power rises rapidly. Therefore, in the baseline offset control mode, the offset voltage value V1 is set to a value smaller than the voltage value at which the properties of the electrorheological fluid change significantly and close to the voltage value at which the properties of the electrorheological fluid change significantly. When the applied voltage is the offset voltage value V1, the ERF damper 5 generates a soft characteristic damping force.

In the baseline offset control mode, the offset voltage value V1 is applied to the electrorheological fluid in advance, so that the damping force of the ERF damper 5 is applied to the electrorheological fluid when the target voltage value V2 (V2> V1) is applied. Can be quickly started up, and by extension, the responsiveness of the damping force of the ERF damper 5 can be improved.

In a control mode that combines an overshoot control mode and a baseline offset control mode, the controller 21 either applies a constant offset voltage value V1 to the electrorheological fluid when the vehicle is in a runnable or running state. , When changing the damping force generated in the ERF damper 5, an overshoot voltage value V3 larger than the target voltage value V2 for generating the target damping force is applied to the electrorheological fluid, and then the target voltage value V2 is applied. Apply.

Referring to FIG. 5, in the control mode in which the overshoot control mode and the baseline offset control mode are combined, the controller 21 sets the vehicle in a runnable state or a running state based on the detection result of the running state detection unit 11 at time T0. When it is detected, the offset voltage value V1 is applied to the electrorheological fluid. The controller 21 applies an overshoot voltage value V3 to the electrorheological fluid when the damping force is changed from the soft characteristic to the hard characteristic at time T1. The controller 21 maintains the applied voltage at the overshoot voltage value V3 during the time T1 and T2, drops the applied voltage from the overshoot voltage value V3 to the target voltage value V2 at the time T2, and sets the applied voltage to the target voltage value. Keep at V2.

Next, with reference to FIG. 6, the control of the controller 21 when switching the traveling mode of the suspension device 1 from the sports mode to the eco mode will be described. The driving mode may be switched, for example, by the driver operating a selector provided in the vehicle interior, or the controller 21 may automatically switch based on the detection result of the driving state detection unit 11. ..

First, when the vehicle is in a traveling state or a traveling state and the damping force characteristic of the ERF damper 5 is a soft characteristic, when the traveling mode is switched from the eco mode to the sports mode at time T0, the controller 21 is electrically operated. An offset voltage value V1 is applied to the viscous fluid. The controller 21 applies an overshoot voltage value V3 to the electrorheological fluid when the damping force is changed from the soft characteristic to the hard characteristic at time T1. The controller 21 maintains the applied voltage at the overshoot voltage value V3 during the time T1-T2, drops the applied voltage from the overshoot voltage value V3 to the target voltage value V2 at the time T2, and maintains the applied voltage at V2. To do. When the applied voltage is the target voltage value V2, the ERF damper 5 generates a damping force having a hard characteristic.

After that, when the driving mode is switched from the sport mode to the eco mode and the damping force is changed from the hard characteristic to the soft characteristic at time T3, the controller 21 applies a voltage value V0 (baseline voltage value) to the electrorheological fluid. Let me. Here, the baseline voltage value V0 in the eco mode is 0 volt. The controller 21 applies an overshoot voltage value V3 to the electrorheological fluid when the damping force is changed from the soft characteristic to the hard characteristic at the time T4. The controller 21 maintains the voltage value at the overshoot voltage value V3 during T4-T5, drops the applied voltage from the overshoot voltage value V3 to the target voltage value V2 at time T5, and sets the applied voltage to the target voltage value V2. To maintain.

As described above, in the present embodiment, when the driving mode is switched from the sports mode to the eco mode, the control mode of the controller 21 is changed from the control mode in which the overshoot control mode and the baseline offset control mode are combined to the overshoot control. You can switch to the mode. On the contrary, when the driving mode is switched from the eco mode to the sports mode, the control mode of the controller 21 is switched from the overshoot control mode to the control mode in which the overshoot control mode and the baseline offset control mode are combined.

In the conventional suspension control, when the damping force is switched from the soft characteristic to the hard characteristic, the response delay of the damping force in the ERF damper, that is, the target voltage value is applied to the electrorheological fluid and then the ERF damper sets the target damping force. The challenge was to eliminate the time lag until it occurred. Here, FIG. 7 shows the time-series waveform of the applied voltage and the time-series waveform of the damping force in the conventional suspension control in an overlapping manner. Referring to FIG. 7, in the conventional suspension control, there is a time lag TL of several tens of milliseconds from the application of the target voltage value V2 to the electrorheological fluid until the ERF damper generates the target damping force. Due to the delay in the response of the damping force, the ride comfort and maneuverability of the vehicle may deteriorate.

On the other hand, in the present embodiment, when the damping force is changed from the soft characteristic to the hard characteristic, an overshoot voltage value V3 (see FIG. 3) larger than the target voltage value V2 is applied to the electrorheological fluid, and the applied voltage is applied. Was maintained at the overshoot voltage value V3 for a certain period of time, and then an overshoot control mode was provided in which the target voltage value V2 was applied. In the overshoot control mode, as shown in FIG. 8, the time lag TL from applying the target voltage value V2 to the electrorheological fluid until the ERF damper 5 generates the target damping force can be reduced to several milliseconds. It is possible. According to the present embodiment, by performing the overshoot control, it is possible to eliminate the response delay of the damping force of the ERF damper 5, and it is possible to improve the maneuverability of the vehicle.

Further, in the present embodiment, when the vehicle is in a traveling state or a traveling state, a constant offset voltage value V1 (see FIG. 4) is applied to the electrorheological fluid to change the damping force from the soft characteristic to the hard characteristic. At this time, a baseline offset control mode was provided in which the target voltage value V2 was applied to the electrorheological fluid. In the baseline offset control mode, as shown in FIG. 9, the time lag TL from applying the target voltage value V2 to the electrorheological fluid until the ERF damper 5 generates the target damping force is reduced to several milliseconds. Is possible. According to the present embodiment, by performing the baseline offset control, the response delay of the damping force of the ERF damper 5 can be eliminated, and the maneuverability of the vehicle can be improved.

Further, in the present embodiment, by performing suspension control in which the overshoot control mode and the baseline control mode are combined, the control mode is set to a control mode with improved running performance (sports mode) and a control mode with improved energy saving performance. You can switch to (eco mode).

1 Suspension device, 5 ERF damper, 21 controller

Claims (5)

A suspension device that generates a damping force according to the voltage value applied to an electrorheological fluid.
A suspension device characterized in that when the damping force is changed, a voltage value larger than a target voltage value for generating a target damping force is applied to the electrorheological fluid, and then the target voltage value is applied. The suspension device according to claim 1, wherein a constant baseline voltage value is applied to the electrorheological fluid when the vehicle is in a traveling state or a traveling state. A method for controlling a suspension device that generates a damping force according to a voltage value applied to an electrorheological fluid.
When the vehicle is in a traveling state or a traveling state, a constant baseline voltage value is applied to the electrorheological fluid.
When changing the damping force, the suspension device is characterized in that a voltage value larger than a target voltage value for generating a target damping force is applied to the electrorheological fluid, and then the target voltage value is applied. Control method. A method for controlling a suspension device that generates a damping force according to a voltage value applied to an electrorheological fluid.
When a constant baseline voltage value is applied to the electrorheological fluid when the vehicle is in a runnable state or a running state, or when the damping force is changed, the electrorheological fluid is subjected to a target damping force. A method for controlling a suspension device, characterized in that a voltage value larger than a target voltage value to be generated is applied, and then the target voltage value is applied or switched. A suspension device that generates a damping force according to the voltage value applied to an electrorheological fluid.
A suspension device characterized in that a constant baseline voltage value is applied to the electrorheological fluid when the vehicle is in a traveling state or a traveling state.

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