JP3791874B2 - Roll control device for vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle roll control device that appropriately controls a roll generated during traveling by adjusting a damping force of a shock absorber mounted on the vehicle.
[0002]
[Prior art]
In general, in a vehicle, as the unsprung weight is lighter and the sprung weight is heavier, the push-up from the road surface during traveling of the vehicle is smaller and the riding comfort is better. In order to absorb this push-up, a spring SP having a relatively large compliance as shown in FIG. 9 is interposed between the sprung weight W1 and the unsprung weight W2.
[0003]
Further, in order to suppress the vibration of the spring SP at an appropriate speed and improve the riding comfort and the maneuverability, a shock absorber SA that absorbs the energy of the vibration is interposed between the sprung weight W1 and the unsprung weight W2. Be dressed.
[0004]
By the way, the vehicle vibrates due to the impact from the road surface and the influence of steering during traveling, and vibrates, for example, around the center line (axis) in the traveling direction of the vehicle body, for example, in the direction of arrow H in FIG. Rolling (rolling) is generated, and this rolling deteriorates the above-described maneuverability of the vehicle.
[0005]
On the other hand, in order to improve the maneuverability by the said roll, what made it possible to set the damping force of a shock absorber to at least two steps has been proposed. Usually, the ride comfort is emphasized and the damping force is set to soft. On the other hand, as shown in FIG. 10, when the lateral gravity acceleration LG of the vehicle exceeds a predetermined threshold value εLG (step S11). ), One damping force of the shock absorber SA on the left and right is controlled hard, and the other is controlled softly (step S12), and the generated roll is suppressed to an appropriate level.
[0006]
Further, in the case where the damping force of the shock absorber can be set in at least two stages, the lateral gravitational acceleration is measured by the lateral gravitational acceleration detecting means of the vehicle and further differentiated to determine the lateral gravitational acceleration. In the same manner as described above, another method is proposed in which the damping force of the shock absorber is switched so as to suppress the roll of the vehicle when the change in the lateral gravitational acceleration exceeds a predetermined threshold. . According to this, it is possible to control the roll with high accuracy and high sensitivity in accordance with a change in the lateral gravity acceleration while the vehicle is traveling.
[0007]
[Problems to be solved by the invention]
However, in the former of the conventional vehicle roll control devices, the road surface is used to continue the roll control while the lateral gravitational acceleration exceeds the threshold during turning of the vehicle. There is a problem that the vehicle body is easily subjected to road surface input (vibration) when there is a seam, and the riding comfort deteriorates.
[0008]
Also, since the damping force of the shock absorber is switched so as to reduce the roll of the vehicle when the lateral gravity acceleration value exceeds a predetermined threshold value, the roll control is turned on and off in the horizontal direction. It is irrelevant to the change in gravitational acceleration, so roll control when the lateral gravitational acceleration is reduced cannot be performed properly as in the case of turning back the steering wheel, and the vehicle continuously runs on a road surface inclined in either the left or right direction. In such a case, there is a problem that the roll control is executed even when the vehicle is not turning.
[0009]
Of the above-described conventional vehicle roll control devices, the latter, in which the lateral gravity acceleration change is obtained by differential calculation, is easily affected by a disturbance signal from the lateral gravity acceleration detecting means due to road surface unevenness. There has been a problem that malfunction may occur due to input from the road surface at this time. At this time, it is conceivable to use a filter circuit to prevent the output of the disturbance signal. However, in this case, there is a problem that the response is deteriorated.
[0010]
The present invention solves the above-described problems, and suppresses deterioration of riding comfort when the vehicle is turning, and is also suitable for roll behavior caused by a decrease in lateral gravity acceleration when the steering is turned back. Another object of the present invention is to provide a vehicle roll control device that can perform accurate roll control and can reliably prevent erroneous roll control from being performed due to road surface inclination or road surface unevenness.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, a roll control apparatus for a vehicle according to the invention of claim 1 is provided in a vehicle and detects a lateral gravity acceleration received by the vehicle while the vehicle is traveling, and a lateral gravity acceleration detecting means. A low-pass filter that passes a signal in a predetermined low frequency region of the lateral gravitational acceleration signal detected by the gravitational acceleration detecting means and a difference between the signal passing through the low-pass filter and the lateral gravitational acceleration signal An arithmetic processing unit for obtaining an estimated value of the change in the direction gravitational acceleration so that the control means suppresses the roll of the vehicle when the estimated value of the change in the lateral direction gravitational acceleration exceeds a preset threshold value. The damping force of the shock absorber is controlled to be switched hard .
[0012]
In the vehicle roll control device according to the second aspect of the present invention, the threshold value can be adjusted according to the vehicle speed detected by the vehicle speed detecting means.
[0013]
According to a third aspect of the present invention, there is provided a vehicle roll control device in which a threshold value can be set to an arbitrary size by a manual operation by a threshold value setting means.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block connection diagram showing a roll control device for a vehicle according to the present invention, which is provided in the vehicle and acts on a traveling vehicle body. A lateral gravity acceleration detecting means 1 for detecting the direction gravity acceleration is provided.
[0015]
A computing device 2 is connected to the lateral gravitational acceleration detecting means 1, and the computing device 2 is a signal in a predetermined low frequency region among the lateral gravitational acceleration signals detected by the lateral gravitational acceleration detecting means 1. And a calculation processing unit 2b that obtains an estimated value dLG of the lateral gravitational acceleration change by taking a difference between the signal passing through the low pass filter 2a and the lateral gravitational acceleration signal.
[0016]
In addition, when the estimated value dLG of the lateral gravitational acceleration change exceeds a preset threshold value, the arithmetic unit 2 applies the damping force of the shock absorbers 3a to 3d in the direction to suppress the roll of the vehicle. A control device 5 for switching control is connected via 4a to 4d.
[0017]
Here, the shock absorbers 3a to 3d are controlled so that the damping force can be adjusted in at least two stages. During normal driving of the vehicle, the damping force is set to a one-step soft mode, and ride comfort is emphasized. ing.
[0018]
Next, the operation will be proved with reference to the flowchart of FIG. First, when the vehicle enters a steady running state, a lateral gravitational acceleration signal as shown by a waveform G shown in FIG. 2a and the arithmetic processing unit 2b.
[0019]
The low pass filter 2a removes a high frequency component in the lateral gravity acceleration signal by its own transfer function (1 + Ts) (Ts is a propagation time), and a predetermined low frequency as shown in a waveform L shown in FIG. Only the components are input to the arithmetic processing unit 2b (step S1). Therefore, the arithmetic processing unit 2b calculates the difference between the low-frequency component signal and the lateral gravity acceleration signal (step S2), and obtains an estimated value dLG of the lateral gravity acceleration change as the calculation result. Note that the estimated value dLG of the lateral gravity acceleration change is as shown by the waveform Y shown in FIG. 4, and is compared with the waveform B of the differential value of the lateral gravity acceleration signal conventionally obtained as the lateral gravity acceleration change. As a result, the waveform is smoothed to suppress the amplitude, and the transfer is delayed by a predetermined time.
[0020]
Next, the control device 5 receives the estimated value dLG of the lateral gravitational acceleration change from the arithmetic device 2, and determines whether or not it exceeds a preset threshold value εdLG (step S3).
[0021]
When the estimated value dLG of the lateral gravity acceleration change exceeds the threshold value εdLG, the control device 5 sets the damping force of the shock absorbers 3a to 3d from the one-step soft mode to the two-step hard mode. As described above, the actuators 4a to 4d are controlled to perform optimum roll control (step S4).
[0022]
On the other hand, when the estimated value dLG of the lateral gravity acceleration change does not exceed the threshold value εdLG, the roll control is not executed. By doing so, it is possible to maintain good riding comfort during low-speed traveling.
[0023]
In this way, a value (estimated value dLG ) corresponding to the lateral gravity acceleration change is calculated from the difference between the lateral gravity acceleration signal and the signal obtained through the low-pass filter 2a, and this lateral gravity acceleration change estimated value dLG is calculated. When the value is smaller than the threshold value εLG, the roll control is not performed. As a result, the roll control is not performed after the roll behavior is settled during steady turning of the vehicle, and as a result, it is possible to avoid deterioration in riding comfort.
[0024]
In addition, since roll control is performed based on the estimated value dLG of the change in lateral gravity acceleration, it is possible to perform appropriate roll control for roll behavior due to a decrease in lateral gravity acceleration when steering is turned back. In addition, when running continuously on a road sloping to the left or right, the behavior is stable and the lateral gravity acceleration does not change, so there is no need for roll control , and normal soft damping force control. This makes it possible to maintain a good ride comfort.
[0025]
Furthermore, in order to perform roll control using the lateral gravity acceleration change estimated value dLG obtained from the lateral gravity acceleration signal and a signal obtained by subjecting this to the low-pass filter signal, the conventional lateral gravity force is obtained by the effect of the low-pass filter processing. Unlike the case where the differential value of acceleration is used as the change value, it is possible to sufficiently avoid the influence of disturbance due to road surface unevenness, and therefore it is possible to suppress malfunction of roll control due to input from the road surface.
[0026]
5, 6 and 7 are characteristic diagrams showing simulation results of the present invention and conventional roll control characteristics. In FIG. 7, the value 0 on the vertical axis of the roll control characteristic is not controlled, ± 1 is roll control (first stage), ± 2 is roll control (second stage), and the sign indicates the left and right direction. Among these, FIG. 5 shows a simulation result at the time of step input. As shown in FIG. 5A, when the vehicle turns at a fixed steering angle, a lateral gravity acceleration signal is temporarily generated by this turning. After starting up, the state becomes stable, but as shown in FIG. 5B , the estimated value dLG of the change in lateral gravitational acceleration decreases with the passage of time after rising up. When the estimated value dLG is equal to or less than a preset threshold value, roll control is not performed as shown in FIG . For this reason, even if the vehicle body receives an impact from the road surface while turning at a constant rudder angle, the damping force of the shock absorber can be controlled softly to prevent deterioration in riding comfort. Conventionally, as shown in FIG. 5D, once the roll control is performed, this is continued until the lateral gravity acceleration signal disappears, and the ride comfort is deteriorated by receiving an impact from the road surface.
[0027]
FIG. 6 shows a simulation result at the time of input of additional steering. In this case, as shown in FIG. The estimated value dLG of the acceleration change occurs twice as shown in FIG. 6 (b). However, since it decreases with the passage of time, the basic roll behavior becomes stable after all. As shown in FIG. 6C, roll control is not performed, and the deterioration of riding comfort can be prevented as in the case described with reference to FIG. 5, and the deterioration of operability does not occur. Conventionally, the roll control is continued as shown in FIG. 6D until there is no lateral gravity acceleration signal.
[0028]
Further, FIG. 7 shows a simulation result at the time of steering switchback input. In this case, the estimated value dLG of the lateral gravitational acceleration change frequently changes as shown in FIG. 7B at the steering switchback timing. In this case, however, the roll behavior due to the decrease of the lateral gravitational acceleration. Also, appropriate roll control as shown in FIG. Conventionally, as shown in FIG. 7D, when the lateral gravitational acceleration is switched to a negative direction, roll control to the left or right of the vehicle body is performed.
[0029]
When the vehicle travels at a high speed while making a large turn on the highway, the lateral gravity acceleration detected by the lateral gravity acceleration detecting means 1 and the estimated value dLG of the lateral gravity acceleration change obtained by the arithmetic unit 2 are obtained. Is substantially constant and does not change significantly, and there is little adverse effect on maneuverability.
[0030]
In this case, vehicle speed detection means 6 is provided, and the control device 5 responds to the change in the vehicle speed on the condition that the current vehicle speed detected thereby exceeds the set vehicle speed VA, as shown in FIG. In addition, by changing the threshold value εdLG, when the lateral gravity acceleration change value dLG greatly changes beyond the threshold value εdLG, the shock absorbers 3a, 3b, 3c, The damping force of 3d can be adjusted.
[0031]
That is, as the vehicle speed increases, the threshold value εdLG is set higher accordingly. Therefore, even if the lateral gravity acceleration change value dLG is large under the condition that the turning radius is large and the influence on the maneuverability is small. Roll control is not performed immediately, so that the riding comfort can be maintained well.
[0032]
Further, according to such a threshold value εLG setting method, frequent switching of the actuators 4a to 4d due to the roll control operation can be suppressed, and deterioration of the riding comfort during high-speed turning on the highway can be prevented.
[0033]
In the above description, a case has been described in which the roll control is automatically switched using the threshold value εdLG stored in advance in a memory or the like in the roll auto control mode. However, the control device 5 shown in FIG. By manually operating a manual setting device 7 as a connected threshold setting means, the magnitude of the threshold value εdLG can be set to an arbitrary level. Depending on the type, the optimal roll control according to the vehicle speed and the lateral gravity acceleration change can be realized.
[0034]
【The invention's effect】
As described above, according to the first aspect of the present invention, the lateral gravitational acceleration detecting means provided on the vehicle for detecting the lateral gravitational acceleration received during traveling of the vehicle, and the lateral gravitational acceleration detecting means are detected. Of the lateral gravitational acceleration signal is obtained by taking a difference between a low-pass filter that passes a signal in a predetermined low frequency region and a signal passing through the low-pass filter and the lateral gravitational acceleration signal. An arithmetic processing unit for obtaining a value, and when the estimated value of the lateral gravitational acceleration change exceeds a preset threshold value, the damping means of the shock absorber is suppressed so that the roll of the vehicle is suppressed. since it is configured so as to switch control to a hard, laterally heavy in suppresses the riding comfort of deterioration during turning of the vehicle, such as when steering the steering-back In addition to enabling the appropriate roll control against rolling behavior due to decreased acceleration, further effect is obtained that from roll control erroneous due to unevenness of the slope and the road surface of the road surface is performed can be reliably prevented.
[0035]
Further, according to the invention of claim 2, since the threshold value is configured to be adjustable according to the vehicle speed detected by the vehicle speed detecting means, such as when traveling on a highway with a large turning radius, etc. Even when the lateral acceleration of gravity is large, it is possible to prevent the roll control from being entered immediately, and to suppress frequent switching of the damping force of the shock absorber, further reducing the deterioration of riding comfort during such high-speed turning. The effect that it can prevent is acquired.
[0036]
Further, according to the invention of claim 3, since the threshold value can be set to an arbitrary size by manual operation by the threshold value setting means, the vehicle body suitable for the driver's own driving feeling and vehicle characteristics can be set. The effect that roll control can be realized arbitrarily is obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a roll control device for a vehicle according to an embodiment of the present invention.
FIG. 2 is a flowchart showing a control procedure of the roll control device in FIG. 1;
FIG. 3 is a signal waveform diagram showing a lateral gravity acceleration signal and a signal after passing through a low-pass filter in the present invention.
FIG. 4 is a signal waveform diagram showing a comparison between a filtered signal of estimated lateral gravity acceleration change value and a signal of lateral gravity acceleration change value obtained by differentiating a conventional lateral gravity acceleration according to the present invention.
FIG. 5 is a signal waveform diagram showing a simulation result at the time of step input of a lateral gravity acceleration signal according to the present invention, an estimated value signal of lateral gravity acceleration change, a roll control signal, and a roll control signal according to a conventional method;
FIG. 6 is a signal waveform diagram showing a simulation result at the time of steering addition of a lateral gravity acceleration signal, an estimated value signal of lateral gravity acceleration change, a roll control signal, and a roll control signal according to a conventional method according to the present invention;
FIG. 7 is a signal waveform diagram showing a simulation result at the time of steering switchback of a lateral gravity acceleration signal according to the present invention, an estimated value signal of lateral gravity acceleration change, a roll control signal, and a roll control signal according to a conventional method.
FIG. 8 is a characteristic diagram showing a threshold-vehicle speed characteristic of the control device according to the present invention.
FIG. 9 is a conceptual diagram showing a general roll control mechanism of a vehicle.
FIG. 10 is a flowchart showing a conventional roll control procedure.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Lateral gravity acceleration detection means 2 Arithmetic apparatus 2a Low-pass filter 2b Arithmetic processing part 3a, 3b, 3c, 3d Shock absorber 5 Control apparatus 6 Vehicle speed detection means 7 Manual setting device (threshold setting means)

Claims (3)

A lateral gravitational acceleration detecting means provided on the vehicle for detecting lateral gravitational acceleration received during traveling of the vehicle, and a predetermined low frequency region of the lateral gravitational acceleration signal detected by the lateral gravitational acceleration detecting means A low-pass filter that passes the signal, a calculation processing unit that obtains an estimated value of the lateral gravitational acceleration change by taking the difference between the signal passing through the low-pass filter and the lateral gravitational acceleration signal, and the lateral gravitational acceleration change A vehicle roll control device comprising: control means for switching the damping force of the shock absorber to hard so as to suppress the roll of the vehicle when the estimated value of the motor exceeds a preset threshold value .   2. The vehicle roll control device according to claim 1, wherein the threshold value can be adjusted according to the vehicle speed detected by the vehicle speed detecting means.   2. The vehicle roll control device according to claim 1, wherein the threshold value can be set to an arbitrary size by a manual operation by a threshold value setting means.

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