JPWO2020066707A1 - Suspension device - Google Patents

Abstract

A second voltage larger than the first voltage value V0 when the damping force is the first voltage value V0 in the soft characteristic region and the steering angular velocity or the front-rear acceleration exceeds the pre-applied threshold value X1. The value V1 is output to the ERF damper 31. Then, when the steering angular velocity or the front-rear acceleration exceeds the hard characteristic change threshold value X2, the third voltage value V2, which is a hard characteristic voltage value exceeding the second voltage value V1, is output to the ERF damper 31. As a result, the damping force of the ERF damper can be quickly switched from the soft characteristic to the hard characteristic.
[Selection diagram] Fig. 3

Description

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

Patent Document 1 discloses a cylinder device using an electrorheological fluid (ERF) as a working fluid, a so-called ERF damper.

International Publication No. 2017/038577

When the damping force is switched from the soft characteristic to the hard characteristic, the suspension device equipped with the ERF damper generates the damping force of the hard characteristic from the voltage value that generates the damping force of the soft characteristic, for example, from the state where the voltage is unloaded. When the voltage is applied stepwise up to the voltage value (hard characteristic command voltage value), it takes time for the damping force to reach the hard characteristic, and there is a problem that the steering stability of the vehicle deteriorates.

An object of the present invention is to provide a suspension device capable of quickly switching the damping force of an ERF damper from a soft characteristic to a hard characteristic.

The suspension device of the present invention includes a cylinder device interposed between the vehicle body and each wheel, a traveling state calculating means for detecting or estimating the traveling state of the vehicle, and the cylinder based on the calculation result of the traveling state detecting means. A suspension device having a controller that calculates a damping force generated in the device and determines a voltage value to be output to the cylinder device based on the calculation result, and the properties of the cylinder device change depending on the applied voltage. The electric viscous fluid is provided in a cylinder in which an electroviscosing fluid is sealed, a piston slidably inserted in the cylinder, and a portion in the cylinder where the flow of the electroviscosing fluid is generated by sliding of the piston. The controller is provided with an electrode that applies an electric field to the viscous fluid, and can be changed from the softest soft characteristic damping force to the hard characteristic damping force by adjusting the voltage applied to the electrode from 0 V to a predetermined voltage. Performs start control to set the first predetermined voltage value larger than 0 V when it is estimated from the calculation result of the traveling state calculating means that it is necessary to increase the damping force of the cylinder device thereafter. It is characterized in that the voltage is normally controlled from a voltage value larger than the first predetermined voltage value to a voltage value at which a damping force of a hard characteristic is generated.

According to the present invention, the damping force of the ERF damper can be quickly switched from the soft characteristic to the hard characteristic.

It is a conceptual diagram of the suspension device which concerns on 1st Embodiment. It is sectional drawing in the axial plane of an ERF damper. It is a block diagram of the suspension control in 1st Embodiment. It is explanatory drawing of 1st Embodiment, and is a time chart diagram which shows the applied voltage and damping force before and after the traveling state calculation value reaches a threshold value. It is a block diagram of suspension control in 2nd Embodiment. It is explanatory drawing of the 3rd Embodiment, and is the time chart figure which shows the applied voltage and the damping force before and after the traveling state calculation value reaches the threshold value.

(First Embodiment)
The first embodiment of the present invention will be described with reference to the attached figure.
Here, a suspension device 1 provided in a four-wheeled vehicle will be illustrated. FIG. 1 is a conceptual diagram of the suspension device 1 according to the first embodiment. Further, FIG. 2 is a cross-sectional view taken along the axis plane of the ERF damper 31 schematically shown in FIG. Note that FIG. 1 shows only the suspension device 1 corresponding to one wheel 3, and the illustrations of the other three wheels and the suspension device corresponding to these wheels are omitted. Further, for convenience, the vertical direction in FIG. 2 is defined as the vertical direction in the ERF damper 31.

Referring to FIG. 1, the suspension device 1 has a suspension spring 4 and an ERF damper 31 (cylinder device) interposed between the vehicle body 2 and the wheels 3. Reference numeral 3A in FIG. 1 is a schematic representation of the tires provided on the wheels 3. The ERF damper 31 is a damping force adjusting type fluid shock absorber that uses an electrorheological fluid as a working fluid. The electrorheological fluid 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) continuously or stepwise adjusts the damping force generated by the ERF damper 31 from the soft characteristic to the hard characteristic by controlling the voltage applied to the electrorheological fluid.

Referring to FIG. 2, the ERF damper 31 has an inner cylinder 32 (cylinder), an outer cylinder 33, and an intermediate cylinder 34. The lower end of the outer cylinder 33 is closed by the bottom cap 15. The lower end of the inner cylinder 32 is fitted to the valve body 37 of the bottom valve 36, and the upper end is fitted to the rod guide 38. An annular reservoir 39 is formed between the inner cylinder 32 and the outer cylinder 33. The electrorheological fluid and gas are sealed in the reservoir 39. The gas in the reservoir 39 is, for example, nitrogen gas.

A piston 40 is slidably provided inside the inner cylinder 32. The lower end of the piston rod 41 is connected to the piston 40. The upper end of the piston rod 41 extends to the outside of the outer cylinder 33 via the rod guide 38. The piston 40 divides the inside of the inner cylinder 32 into two chambers, a cylinder upper chamber 42 and a cylinder lower chamber 43. The piston 40 is provided with a contraction side passage 44 and an extension side passage 45 for communicating the cylinder upper chamber 42 and the cylinder lower chamber 43.

Here, the ERF damper 31 has a uniflow structure. That is, the ERF damper 31 transfers the electrorheological fluid from the cylinder upper chamber 42 to the inner cylinder 32 via the passage 46 provided in the inner cylinder 32 in both the contraction stroke and the extension stroke of the piston rod 41. It is circulated to the annular flow path 47 formed between the cylinder 34 and the cylinder 34. In order to form the uniflow structure, the upper end surface of the piston 40 functions as a check valve in the extension stroke, and the extension side reverse that allows the flow of the electroviscous fluid from the cylinder lower chamber 43 to the cylinder upper chamber 42 in the contraction stroke. A check valve 48 is provided, and a contraction side check valve 49 that functions as a relief in the extension stroke and a check valve in the contraction stroke is provided on the lower end surface of the piston 40.

The extension-side check valve 48 opens during the contraction stroke of the piston rod 41 and allows the flow of electrorheological fluid from the cylinder lower chamber 43 to the cylinder upper chamber 42 via the contraction-side passage 44. On the other hand, the contraction side check valve 49 opens when the pressure in the cylinder upper chamber 42 reaches a predetermined pressure during the extension stroke of the piston rod 41, and the pressure in the cylinder upper chamber 42 is extended on the extension side. Relieve to the cylinder lower chamber 43 via the passage 45.

The valve body 37 partitions the reservoir 39 and the cylinder lower chamber 43. An annular holding member 50 is fitted on the outer circumference of the inner cylinder 32 fitted to the small diameter portion of the valve body 37. The holding member 50 positions the lower end of the intermediate cylinder 34 in the axial direction (vertical direction) and the radial direction. The holding member 50 is made of an electrically insulating material and electrically insulates the inner cylinder 32, the bottom cap 35, and the valve body 37 from the intermediate cylinder 34. The holding member 50 is formed with a passage 51 that communicates an annular flow path 47 formed between the inner cylinder 32 and the intermediate cylinder 34 with the reservoir 39. The valve body 37 has a contraction-side check valve 200 that allows the flow of an electroviscous fluid from the reservoir 39 to the cylinder lower chamber 43 during the expansion stroke and functions as a check valve during the contraction stroke, and a cylinder lower chamber during the contraction stroke. When the pressure of 43 reaches a predetermined pressure, a valve is opened from the lower chamber 43 of the cylinder toward the reservoir 39 to allow an electrically viscous fluid to flow, and an extension-side check valve 201 that functions as a check valve during the extension stroke is provided.

The intermediate cylinder 34 is made of a conductive material. The upper end portion of the intermediate cylinder 34 is positioned coaxially with respect to the piston rod 41 via a holding member 52 and a rod guide 38 fitted to the outer peripheral surface of the upper end portion of the inner cylinder 32. The holding member 52 is made of an electrically insulating material and electrically insulates the intermediate cylinder 34 from the inner cylinder 32. Further, the intermediate cylinder 34 is connected to the positive electrode of the battery 6 via the high voltage driver 7. That is, the intermediate cylinder 34 constitutes a positive electrode (electrode) that applies an electric field (voltage) to the electrorheological fluid flowing in the annular flow path 47.

On the other hand, the inner cylinder 32 used as the negative electrode (ground electrode) is connected to the ground via the valve body 37, the bottom cap 35, the outer cylinder 33, and the high voltage driver 7. In FIG. 2, the electrode connection portion with the positive electrode is provided in the intermediate cylinder 34, and the ground connection portion with the negative electrode electrode (ground electrode) is provided in the inner cylinder 32. The ground connection portion of the above may be provided in the intermediate cylinder 34, and the electrode connection portion with the positive electrode may be provided in the inner cylinder 32, or similarly, the inner cylinder 32 and the outer cylinder 33 may be provided.

On the other hand, when comparing the flow path cross-sectional areas between the inner cylinder 32 and the intermediate cylinder 34 and between the intermediate cylinder 34 and the outer cylinder 33, the damping force generated when a voltage is applied to the electrorheological fluid is Since it is determined by the amount of current (cross-sectional area) between the electrodes, it is better to apply a voltage between the inner cylinder 32 and the intermediate cylinder 34 because the cross-sectional area between the electrodes is smaller, so that the applied voltage is smaller, that is, The same damping force (braking force) can be obtained with less current consumption. Further, when the amount of energization increases due to an increase in the liquid temperature, it is possible to prevent the power supply from becoming overloaded by reducing the amount of energization to reduce the load on the power source. Further, the ground may be ground, a frame ground, a signal ground, or the like. Finally, the current from the positive electrode may be connected to the reference potential point.

As shown in FIG. 1, the positive electrode of the battery 6 is connected to the intermediate cylinder 34, which is the electrode on the positive electrode side of the ERF damper 31, 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 32 of the ERF damper 31 via the high voltage driver 7. The high voltage driver 7 boosts the DC voltage (Batt voltage) output from the battery 6 and outputs it to the ERF damper 31 (high voltage output) based on the high voltage command output from the controller 21. 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. On the other hand, the high voltage driver 7 monitors the current value before being boosted by the booster circuit, and outputs a monitor signal of the current value to the controller 21 as a Batt current monitor value.

The suspension device 1 has a traveling state calculation unit 11 (traveling state calculating means) that detects or estimates the traveling state of the vehicle. The controller 21 controls the damping force generated by the ERF damper 31 (hereinafter referred to as “damping force”) based on the detection result of the traveling state calculation unit 11. That is, the controller 21 executes the high voltage command calculation using the detection result of the traveling state calculation unit 11 and calculates the high voltage command to be output to the high voltage driver 7. Then, the high voltage driver 7 outputs a high voltage corresponding to the high voltage command output from the controller 21 to the ERF damper 31. As a result, a voltage corresponding to the output (high voltage output) of the high voltage driver 7 is applied to the electrorheological fluid flowing through the annular flow path 47 between the intermediate cylinder 34 and the inner cylinder 32 of the ERF damper 31. As a result, the viscosity (property) of the electrorheological fluid changes according to the potential difference between the intermediate cylinder 34 and the inner cylinder 32, and the damping force is adjusted (switched).

Next, the operation of the first embodiment will be described with reference to FIGS. 3 and 4. Here, FIG. 3 is a block diagram of suspension control by the controller 21, and FIG. 4 is a time chart diagram of damping force, applied voltage, and calculated running state.
As an example, the traveling state calculation unit 11 includes a steering angle detection unit 12 and a front-rear acceleration detection unit 13 as vehicle behavior detection means. The steering angle detection unit 12 detects the steering angle from the steering angle (not shown) or the turning angle of the wheel 3. The front-rear acceleration detection unit 13 detects the front-rear acceleration from the front-rear acceleration sensor and the wheel speed of the wheel 3.

The controller 21 calculates the roll state of the vehicle from the detection value of the steering angle detection unit 12 and the integrated value of the front-rear acceleration detection unit 13 or the vehicle speed value from the vehicle. In this roll state, the roll angle, the roll angular velocity, and the roll angular acceleration are calculated. Further, the pitch angle, pitch angular velocity, and pitch angular velocity of the vehicle body 2 are calculated based on the detection values of the front-rear acceleration detection unit 13. Further, the controller 21 has a preliminary application threshold value determination unit 22, a control command unit 23, and a hardware side characteristic change threshold value determination unit 24.

The pre-applied threshold value determination unit 22 determines whether the roll angular acceleration or the pitch angular acceleration as the running state calculation value in FIG. 4 exceeds the pre-applied threshold value X1 which is each predetermined threshold value. That is, from the calculation result of the traveling state calculation unit 11, it is determined (estimated) whether it may be necessary to increase the damping force of the ERF damper 4 (cylinder device) after that because the roll angular velocity and the pitch angular velocity increase. )do.

When the pre-applied threshold value determination unit 22 determines (estimates) that it may be necessary to increase the damping force thereafter, that is, the roll angular acceleration or the pitch angular acceleration is at their respective predetermined threshold values. When a certain preliminary application threshold value X1 is exceeded, a command to apply the first predetermined voltage value V1 to the high voltage driver 7 is output from the control command unit 23, whereby the first predetermined voltage value V1 is sent to the ERF damper 31. It is applied.

Here, the first predetermined voltage value V1 is a small voltage value larger than 0V and generating a soft characteristic damping force. As a result, the damping force of the ERF damper 31 becomes a damping force F1 (see FIG. 4) that is slightly larger than the damping force F0 when no voltage is applied, but the damping force is at a level that does not substantially affect the vehicle. With the increase, the soft damping force is substantially maintained. This is called preliminary application control (start control).

After that, the hard side characteristic change threshold value determination unit 24 determines whether the roll angular acceleration or the pitch angular acceleration exceeds the hard side change threshold value X2, which is a predetermined threshold value larger than the respective preliminary application threshold values X1. After that, the control command unit 23 calculates the control command value required to generate the damping force according to the roll angular velocity and the pitch angular velocity, and outputs the command to the high voltage driver 7. In response to this, the high voltage driver 7 applies a voltage larger than the voltage V1 (voltage value between V1 and V2) to the ERF damper 31. As a result, the ERF damper 31 generates a damping force on the hard side such as F2, F3, and F4, which is larger than F1, and executes a normal damping force control (normal control) according to the traveling state.

Further, in the hard side characteristic change threshold value determination unit 24, the controller 21 did not exceed the hard side change threshold value X2 for a predetermined time (for example, 30 ms) after the roll angular angle acceleration or the pitch angle angular acceleration exceeded the preliminary application threshold value X1. In the case, the application of the preliminary applied voltage is stopped. The application of the preliminary applied voltage may be stopped when the pitch angular acceleration exceeds the preliminary application threshold value X1 and then when the pitch angular acceleration falls below the preliminary application threshold value X1. Further, a lateral acceleration sensor may be used instead of the steering angular velocity detection unit 12, as long as it can detect the roll state.

Next, the control of the controller 21 for switching the damping force from the soft characteristic to the hard characteristic will be described with reference to FIG. 4 by taking as an example when the vehicle travels in a corner.
The detection result of the running state calculation unit 11 (running state calculation means) at the time point T0, that is, the detection value of the steering angular velocity detection unit 12 (hereinafter referred to as “steering angular velocity”), the front-rear speed which is the detection value of the front-rear acceleration detection unit 13, and the front-rear speed. The roll angular velocity is obtained from the front-back acceleration, and the value is differentiated to obtain the roll angular velocity. At this time point T0, the roll angular acceleration is a value smaller than the preliminary application threshold value X1.

The running state of the vehicle assumed at the time point T0 is, for example, when the vehicle is stopped, is running linearly (the steering angle is not cut), or is a steady circular turn that runs at a constant speed at a constant steering angle. It is in a state. That is, it is not in a state (behavior) in which a roll speed higher than a predetermined value is generated. At this time, the controller 21 determines that the softest soft characteristic damping force F0 (damping force F0 in the soft characteristic region) is required, and the controller 21 does not issue a high voltage command. As a result, no voltage is applied, so that the electrorheological fluid is in a no-load state. In other words, the controller 21 has a soft characteristic damping force F0 (a damping force F0 in the soft characteristic region).

Next, at the time point T1, the steering angular velocity changes from 0 in the steering angular velocity detection unit 12 due to the start of turning the steering, so that the roll angular acceleration increases instantaneously. The pre-applied threshold value determination unit 22 compares the roll angular acceleration with the pre-applied threshold value X1 at the time point T1, and determines that the pre-applied threshold value X1 has been exceeded. In response to this determination, the controller 21 estimates that it will be necessary to increase the damping force of the ERF damper 31 thereafter, and performs preliminary application control (start control).

Here, the control command unit 23 outputs a high voltage command of the first predetermined voltage value V1, which is larger than V0 = 0V and is a small voltage value that generates a soft characteristic damping force, to the high voltage driver 7. Then, the high voltage driver 7 receives the high voltage command and outputs a high voltage of the first predetermined voltage value V1 to the ERF damper 31. As a result, the first voltage value V1 is applied to the electrorheological fluid as a preliminary applied voltage from the state where the voltage is unloaded. As a result, the ERF damper 31 generates a damping force F1 substantially equal to the damping force F0, which is a soft characteristic, to the extent that the soft characteristic does not affect the riding comfort of the vehicle.

Next, at time point T2 (about 10 to 20 ms from T1), the roll angular acceleration due to turning the steering further than at time point T1 is compared with the hard side characteristic change threshold value X2, and the hard side characteristic change threshold value X2 is set. Judge that it has been exceeded. In response to this determination, the control command unit 23 calculates a high voltage command value according to the roll angular velocity and outputs the high voltage command value to the high voltage driver 7. Then, the high voltage driver 7 receives this high voltage command and outputs a voltage at which the damping force necessary for suppressing the roll speed is generated to the ERF damper 31. As a result, the ERF damper 31 generates, for example, a damping force F2 on the maximum hard characteristic side.

That is, in the first embodiment, when the damping force is the voltage value 0V in the soft characteristic region and the roll angular acceleration or the pitch angular acceleration exceeds the preliminary application threshold X1, the first predetermined voltage value. Start control is performed to output V1 to the ERF damper 31. Then, when the roll angular acceleration or the pitch angular acceleration exceeds the preliminary application threshold X1 and then exceeds the hard side characteristic change threshold X2, the hard side characteristic voltage value exceeds the first predetermined voltage value V1. Normal control is performed to output the voltage between the voltage values V1 and V2 to the ERF damper 31. Note that FIG. 4 shows a case where the overvoltage of the software is changed from the voltage value V1 of the software to the voltage value V2 of the maximum hardware side at once.

As described above, in the first embodiment, the damping force of the ERF damper 31 that generates the damping force of the hard side characteristic to the electrorheological fluid in the state where the pre-applied voltage of the first predetermined voltage value V1 is applied is obtained from the soft characteristic. It is possible to quickly switch to the hardware side characteristics. Here, FIG. 4 shows the case where the preliminary applied voltage V1 is changed to the maximum voltage value V2 at once, which is shown by the solid line, and the state where there is no applied voltage (V0) of the conventional control, which is shown by the broken line, to the maximum at once. When the voltage value is switched to V2 (hereinafter referred to as "conventional control"), is indicated.

Referring to FIG. 4, when a voltage is applied to the electrorheological fluid in a step-like manner from a no-load state at time point T2, from time point T2 to time point T4 when the damping force of the conventional control reaches F4 of the first peak from F0. After rising, the damping force gradually increases until the time point T6, reaching the damping force F2 with the maximum hard characteristics. Here, T6 varies depending on conditions such as the type of electrorheological fluid and the distance between electrodes, but it takes about 250 ms. In this way, in the conventional control, when the damping force is switched from the soft characteristic to the maximum hard characteristic, the voltage is stepped from the voltage V0 that generates the damping force of the soft characteristic to the voltage value V2 that generates the damping force of the hard characteristic. When applied, it takes time for the damping force of the ERF damper to reach the hard characteristics, and there is a problem that the steering stability of the vehicle deteriorates.

On the other hand, in the first embodiment, the second voltage value V2 that generates the damping force of the hard characteristic at the time point T2 in the electrorheological fluid in the state where the first predetermined voltage value V1 which is the preliminary applied voltage is applied. When the voltage of In 2 hours, the damping force rises from F1 to the first peak F3. Here, the damping force F3 of the first peak in the first embodiment is about twice the damping force F4 of the first peak in the conventional control. It should be noted that the reason why the first peak is generated in the first embodiment and the prior art is due to the characteristics of the electrorheological fluid, and the mode of change differs depending on the characteristics of the electrorheological fluid.

Then, in the first embodiment, the damping force reaches the damping force F2 of the maximum hard characteristic at the time point T5. In the first embodiment, the time (T5-T2) required for the damping force to reach the damping force F2 of the maximum hard characteristic at the time point T5 after the controller 21 outputs the maximum hard characteristic voltage command at the time point T2 is determined. In the conventional control, about 1 of the time (T6-T2) required for the damping force to reach the damping force F2 of the maximum hard characteristic at the time point T6 after the controller 21 outputs the maximum hard characteristic voltage command at the time point T2. It is / 2.

As described above, in the first embodiment, by performing the start control in which the first predetermined voltage value V1 which is the preliminary applied voltage is applied to the electrorheological fluid in advance, the responsiveness when the control is subsequently shifted to the normal control is improved. be able to. That is, when the first predetermined voltage value V1 which is the preliminary applied voltage is applied to the electrorheological fluid, the arrangement of the fine particles dispersed in the base oil of the electrorheological fluid changes, and then a damping force having a hard characteristic is generated. When the voltage value V2 is applied, the time required for the fine particles whose arrangement has changed to form a cluster structure can be significantly shortened, and the responsiveness of the damping force can be improved.

In the first embodiment, the following effects are obtained.
According to the first embodiment, the cylinder device interposed between the vehicle body and each wheel, the traveling state calculating means for detecting or estimating the traveling state of the vehicle, and the calculation result of the traveling state detecting means are used. A suspension device having a controller that calculates the damping force generated in the cylinder device and determines the voltage value to be output to the cylinder device based on the calculation result, and the properties of the cylinder device change depending on the applied voltage. A cylinder in which an electroviscous fluid is sealed, a piston slidably inserted into the cylinder, and a portion where the electroviscosity fluid flows due to sliding of the piston in the cylinder are provided to apply an electric voltage to the electroviscosity fluid. It is equipped with an electrode to be applied, and the voltage applied to the electrode can be changed from the softest soft characteristic damping force to the hard characteristic damping force by adjusting the voltage applied to the electrode from 0 V to a predetermined voltage. When it is estimated from the calculation result that it is necessary to increase the damping force of the cylinder device thereafter, start control is performed to set the first predetermined voltage value larger than 0V, and then the voltage is set from the first predetermined voltage value. Normal control is performed between a large voltage value and a voltage value that generates a damping force of hard characteristics.

As described above, in the first embodiment, when the damping force is a voltage value of 0V in the soft characteristic region and it is estimated that it is necessary to increase the damping force of the cylinder device thereafter, the electrorheological fluid is more than 0V. A pre-applied voltage, which is a large first predetermined voltage value, is applied, and then a voltage that generates a damping force larger than the soft characteristic is applied. As a result, the damping force of the cylinder device can be quickly switched from the soft characteristic to the hard characteristic, and the deterioration of the steering stability of the vehicle due to the delay in the rise of the damping force with respect to the high voltage command of the controller can be suppressed. can.

Further, since the first predetermined voltage value is set to such an extent that the riding comfort of the vehicle is not deteriorated, the pre-applied voltage is applied to the electrorheological fluid while the first predetermined voltage value is output from the controller. The ride quality of the vehicle can be ensured while the vehicle is being driven.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIG.
The same titles and symbols will be used for the common parts with the first embodiment, and duplicate description will be omitted.

In the first embodiment, the traveling state calculation means 11 includes a sensor that detects the front / rear, left / right, yaw position, speed, and acceleration, and a sensor that detects the amount of operation by the driver such as the accelerator, brake, and steering. It was configured by behavior detection means.
On the other hand, in the second embodiment, the traveling state calculation means 11 is configured by an external world recognition means including a vertical acceleration sensor, a camera, and the like. Referring to FIG. 5, the traveling state calculating means 11 in the second embodiment is composed of a road surface state grasping unit 15 (outside world recognizing means) for detecting an uneven state of the road surface.

The road surface condition grasping unit 15 uses a vehicle body vertical acceleration sensor, an in-vehicle camera, a car navigation system, a laser sensor, etc. that can communicate with the controller 21, for example, CAN (Controller Area Network), LIN (Local Interconnect Network), PSI5. It may be obtained from in-vehicle communication using (Peripheral Sensor Interface 5), DSI (Distributed Systems Interface), MOST (Media Oriented Systems Transport), etc., and is not limited to the above-mentioned communication, but as external communication (V2X: Vehicle). to everything), IEEE 802.11p, LTE-V2X (PC-5), ITS-G5, WAVE-DSRC, etc. may be used to connect to the controller 21, and the external network as part of the HMI (Human Machine Interface). May be connected with.

Next, the control of the controller 21 that switches the damping force from the soft characteristic to the hard characteristic will be described.
In the second embodiment, when the damping force is the voltage value V0 = 0V in the soft characteristic region, the road surface condition recognized by the road surface condition grasping unit 15, that is, the rate of change (jerk) of the output of the vertical acceleration sensor. ERF damper 31 sets the first predetermined voltage value V1, which is larger than the voltage value V0, when the value of Performs preliminary application control (start control) to output to. Then, when the road surface condition detection value exceeds the preliminary application threshold value X1 and then the road surface condition detection value exceeds the hard characteristic change threshold value X2, the voltage value V2, which is a hard characteristic voltage value exceeding the first predetermined voltage value V1. Is normally controlled to output to the ERF damper 31.

According to the second embodiment, the same effects as those of the first embodiment described above can be obtained. Further, even in an automatic driving state where there is no driver, it is possible to perform quick attitude control of the vehicle as compared with the conventional technique.
In particular, by connecting to a safety-related communication network such as PSI5 or DSI, it is possible to quickly change to hard characteristics during emergency avoidance braking, so it is possible to suppress unwanted vehicle behavior and improve occupant safety.

In addition, the above-mentioned first embodiment and the second embodiment may be combined and carried out.
Further, the traveling state calculation unit may be capable of predicting the occurrence of a stroke equal to or greater than a predetermined value of the ERF damper, and thereby, a preliminary application control (start control) in which a preliminary application voltage is applied at a stage where the stroke is predicted to occur. After that, the normal damping force control (normal control) that outputs the voltage corresponding to the required damping force from the high voltage driver is executed.
Further, when the occurrence of the stroke is not expected, the power can be saved by performing the preliminary application stop control for stopping the preliminary application voltage.
Further, in the control performed by the controller 21, when it is estimated that it is necessary to increase the damping force of the ERF damper 31 thereafter, a pre-applied voltage which is a first predetermined voltage value larger than 0 V is applied to the electrorheological fluid. This is a feed-forward control that applies a pre-applied voltage, which is a first predetermined voltage value larger than 0 V, to the electrorheological fluid when it is necessary to increase the damping force of the ERF damper 31. You may.

(Third Embodiment)
This will be described with reference to FIG. 6 to which the third embodiment of the present invention is attached.
The same titles and symbols will be used for the common parts with the first embodiment, and duplicate description will be omitted.

In the first embodiment, the controller 21 attenuates the ERF damper 31 (cylinder device) from the calculation result of the traveling state calculation unit 11 (traveling state calculating means) when the damping force is the voltage value 0V in the soft characteristic region. When it is estimated that it is necessary to increase the force thereafter, start control is performed to apply a pre-applied voltage which is a first predetermined voltage value larger than 0 V to the electroviscosity fluid, and then the voltage is set to the first predetermined voltage. Normal control is performed from a voltage value larger than the value to a voltage value that generates a damping force of hard characteristics.

On the other hand, in the third embodiment, the controller 21 performs base control in which a first predetermined voltage value V1 larger than 0V is constantly applied to the electrorheological fluid except when 0V is output. Here, the running state of the vehicle when 0V is output is, for example, a stopped state.

Next, with reference to FIG. 6, the control of the controller 21 for switching the damping force from the soft characteristic to the hard characteristic will be described.
At the time point T0, the controller 21 recognizes that the vehicle is in the stopped state from the detection result of the traveling state calculation unit 11 (traveling state calculating means), that is, the detection result of the vehicle behavior detecting means or the outside world recognizing means described above. At this time, since the controller 21 does not issue a high voltage command, the damping force generated by the ERF damper 31 is the soft characteristic damping force F0 (damping force F0 in the soft characteristic region).

Next, at the time point T1, the controller 21 recognizes that the vehicle is not in the stopped state from the detection result of the traveling state calculation unit 11. As a result, the controller 21 performs base control in which a first predetermined voltage value V1 larger than 0 V is constantly applied to the electrorheological fluid. Here, the controller 23 outputs a high voltage command of the first predetermined voltage value V1 to the high voltage driver 7. Then, the high voltage driver 7 receives the high voltage command and outputs a high voltage of the first predetermined voltage value V1 to the ERF damper 31. As a result, the first voltage value V1 is applied to the electrorheological fluid as a preliminary applied voltage from the state where the voltage is unloaded. As a result, the ERF damper 31 generates a damping force F1 that is substantially equivalent to the damping force F0, which is a soft characteristic, to the extent that the ride quality of the vehicle is not affected by the soft characteristic.

Next, at the time point T2, the controller 21 determines that the detection result of the traveling state calculation unit 11 exceeds the hardware side characteristic change threshold value X2. In response to this determination, the controller 21 outputs a high voltage command value according to the detection result of the traveling state calculation unit 11 to the high voltage driver 7. Then, in response to this high voltage command, the high voltage driver 7 outputs a voltage to the ERF damper 31 that generates a damping force necessary for suppressing vehicle behavior (for example, roll). As a result, the ERF damper 31 generates, for example, a damping force F2 on the maximum hard characteristic side.

As described above, in the third embodiment, the damping force of the ERF damper 31 that generates the damping force of the hard side characteristic is applied to the electrorheological fluid in the state where the pre-applied voltage of the first predetermined voltage value V1 is constantly applied, which is the soft characteristic. Can be quickly switched from to hard side characteristics.
According to the third embodiment, it is possible to obtain the same effect as that of the first embodiment described above.
In addition, the above-mentioned second embodiment and the third embodiment may be combined and carried out.

1 Suspension device, 2 car body, 3 wheels, 5 ERF damper (cylinder device), 11 running state calculation means, 21 controller

Claims (7)

A cylinder device interposed between the vehicle body and each wheel,
A running state calculation means for detecting or estimating the running state of a vehicle,
A controller that calculates the damping force generated in the cylinder device based on the calculation result of the traveling state detecting means and determines the voltage value to be output to the cylinder device based on the calculation result.
Suspension device with
The cylinder device
A cylinder filled with an electrorheological fluid whose properties change depending on the applied voltage,
A piston slidably inserted into the cylinder and
An electrode provided in a portion of the cylinder where the flow of the electrorheological fluid is generated by sliding of the piston and applying an electric field to the electrorheological fluid is provided.
By adjusting the voltage applied to the electrode from 0V to a predetermined voltage, it is possible to change from the softest soft characteristic damping force to the hard characteristic damping force.
The controller
When it is estimated from the calculation result of the traveling state calculating means that it is necessary to increase the damping force of the cylinder device thereafter, start control is performed to set the first predetermined voltage value larger than 0V, and then the voltage is applied. The suspension device is characterized in that normal control is performed between a voltage value larger than the first predetermined voltage value and a voltage value that generates a damping force having a hard characteristic. The suspension device according to claim 1, wherein the first predetermined voltage value is a voltage value equal to or lower than a voltage value determined by the controller when switching to the normal control. The suspension device according to claim 1, wherein the first predetermined voltage value is larger than 0 V and is a small voltage value that generates a soft characteristic damping force. A cylinder device interposed between the vehicle body and each wheel,
A running state calculation means for detecting or estimating the running state of a vehicle,
A controller that calculates the damping force generated in the cylinder device based on the calculation result of the traveling state detecting means and determines the voltage value to be output to the cylinder device based on the calculation result.
Suspension device with
The cylinder device
A cylinder filled with an electrorheological fluid whose properties change depending on the applied voltage,
A piston slidably inserted into the cylinder and
An electrode provided in a portion of the cylinder where the flow of the electrorheological fluid is generated by sliding of the piston and applying an electric field to the electrorheological fluid is provided.
By adjusting the voltage applied to the electrode from 0V to a predetermined voltage, it is possible to change from the softest soft characteristic damping force to the hard characteristic damping force.
The controller
A suspension device characterized by performing base control in which a first predetermined voltage value larger than 0V is constantly applied except when 0V is output. The suspension device according to any one of claims 1 to 4, wherein the traveling state calculating means calculates a traveling state based on information from the outside world recognition means. The suspension device according to any one of claims 1 to 4, wherein the traveling state calculating means calculates a traveling state based on information of a vehicle behavior detecting means provided on the vehicle body. The suspension device according to claim 6, wherein the traveling state calculating means estimates a traveling state based on a value estimated from the information of the vehicle behavior detecting means.

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