JP2011152887A - Vehicular suspension control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make both compatible in maintenance of a stroke feeling and an improvement in damping. <P>SOLUTION: A sprung speed V1 is detected by a sprung acceleration sensor 8 and an integrator 11. A relative speed V2 between a vehicle body 1 and a wheel 2 is detected by the sprung acceleration sensor 8, an unsprung acceleration sensor 9, a subtracter 13 and the integrator 12. A gain map 14 outputs target damping force DF corresponding to the sprung speed V1. This gain map 14 has nonlinear gain K, and increases gain of the target damping force DF more than when being smaller than a threshold value Vt when the size of the sprung speed V1 is larger than the threshold value Vt. A damping force map 15 determines an electric current command value based on the target damping force DF and the relative speed V2. Thus, the maintenance of the stroke feeling and the improvement in the damping can be made compatible in both by changing the gain of the target damping force DF in response to the sprung speed V1. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a vehicle suspension control device that is mounted on a vehicle such as a four-wheeled vehicle, and is preferably used for buffering vibrations of the vehicle.

  In general, a vehicle such as an automobile is provided with a damping force adjustment type shock absorber between a vehicle body and each axle, and a suspension control device configured to adjust a damping force characteristic by the shock absorber using an adjustment signal is mounted. (For example, see Patent Documents 1 and 2).

  In this type of conventional vehicle suspension control device, for example, vibrations in the upward and downward directions of the vehicle body are detected as sprung speeds or sprung accelerations, and buffering is performed so as to generate a damping force corresponding to the detected speeds. An adjustment signal was output to the device.

JP-A-8-142625 JP 2006-347530 A

  By the way, in the above-described vehicle suspension control device according to the prior art, if the gain for adjusting the damping force according to the sprung speed or the like is increased in order to increase the control effect, the hardness of the shock absorber increases. In addition, a feeling of stroke such that the displacement in the upper and lower directions of the tire follows the road surface is impaired. On the other hand, if the gain of the damping force is reduced, the feeling of stroke is improved, but the control effect is reduced, and the damping (damping effect) that attenuates the vibration in the upper and lower directions of the vehicle is lowered. Thus, the stroke feeling and the damping have a trade-off relationship with respect to the gain of the damping force, and these tend to be difficult to achieve at the same time.

  With respect to such a problem, Patent Document 1 discloses a configuration in which when the sprung speed exceeds a threshold value, the damping force gain is increased over a predetermined number of vibrations to increase the damping effect. Is disclosed. Patent Document 2 discloses a configuration in which the damping force gain is increased to increase the damping effect when the amplitude of sprung acceleration or sprung speed exceeds a set value.

  However, in the configurations of Patent Documents 1 and 2, since the gain is increased until the release condition is satisfied after the condition for increasing the gain of the damping force is satisfied, the case where the damping force is too large may occur. There is a problem that the feeling of riding is lost due to loss of feeling.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a vehicle suspension control apparatus capable of improving damping while maintaining a feeling of stroke. .

  In order to solve the above-described problem, the invention according to claim 1 includes a damping force adjustment type shock absorber that is interposed between a vehicle body and a wheel of a vehicle and that adjusts damping force characteristics using an adjustment signal. In the vehicle suspension control apparatus, a vehicle body side vertical speed detection unit that detects the vehicle body vertical speed as the vehicle body vertical speed, and the damping force based on the vehicle body vertical speed by the vehicle side vertical speed detection unit. A damping force calculation unit that calculates a target damping force to be generated in the adjustable shock absorber, a relative speed detection unit that detects a relative speed in the up and down direction between the vehicle body and the wheel, and a target by the damping force calculation unit An adjustment signal output unit that outputs an adjustment signal for adjusting the damping force characteristic of the damping force adjusting shock absorber based on the damping force and the relative speed by the relative speed detection unit, and the damping force calculation unit includes the vehicle body Side up / down speed is The target damping force that shifts the target damping force to the hard side when it is larger than the predetermined threshold value, and that shifts the target damping force to the soft side when the vehicle body side vertical speed is smaller than the threshold value. It is characterized by having a structure having a shift means.

  According to the present invention, damping can be improved while maintaining a feeling of stroke.

It is a figure showing typically a suspension control device by an embodiment of the invention. It is a block diagram which shows the controller in FIG. It is explanatory drawing which shows the gain map in FIG. It is explanatory drawing which shows the damping force map in FIG. It is a characteristic diagram which shows the part by which the sprung speed is a positive side among nonlinear gains. It is explanatory drawing which shows the relationship between a feeling of stroke and damping. It is a characteristic diagram which shows the time change of sprung speed and target damping force.

  Hereinafter, a vehicle suspension apparatus according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings, taking as an example a case where it is applied to a four-wheeled vehicle.

  1 to 5 show an embodiment of the present invention. In the figure, reference numeral 1 denotes a vehicle body constituting a vehicle body. On the lower side of the vehicle body 1, for example, left and right front wheels and left and right rear wheels (hereinafter collectively referred to as wheels 2) are provided. The wheel 2 includes a tire 3. At this time, the tire 3 acts as a spring that absorbs fine irregularities on the road surface.

  Reference numeral 4 denotes a suspension device provided between the vehicle body 1 and the wheel 2, and the suspension device 4 is arranged in parallel with a suspension spring 5 (hereinafter referred to as a spring 5) and the spring 5. And a damping force adjusting shock absorber (hereinafter referred to as shock absorber 6) provided between the wheel 2 and the wheel 2. FIG. 1 illustrates a case where a set of suspension devices 4 is provided between the vehicle body 1 and the wheels 2. However, for example, a total of four suspension devices 4 are individually provided between the four wheels 2 and the vehicle body 1, and only one of these is schematically illustrated in FIG. 1. .

  Here, the shock absorber 6 of the suspension device 4 is configured using a damping force adjusting hydraulic shock absorber. The shock absorber 6 includes a damping force adjusting valve or the like for continuously adjusting the generated damping force characteristic (damping force characteristic) from a hard characteristic (hard characteristic) to a soft characteristic (soft characteristic). An actuator 7 is attached. Note that the damping force adjusting valve may be capable of adjusting the damping force characteristic in two steps or a plurality of steps without being continuous.

  Reference numeral 8 denotes a sprung acceleration sensor provided in the vehicle body 1, and the sprung acceleration sensor 8 is in the vicinity of the shock absorber 6, for example, in order to detect the vibration acceleration in the upward and downward directions on the side of the vehicle body 1 that is a so-called spring upper side. It is attached to the vehicle body 1 at a position. The sprung acceleration sensor 8 detects the vibration acceleration in the upward and downward directions, and outputs a detection signal to the controller 10 described later.

  Reference numeral 9 denotes an unsprung acceleration sensor provided on the wheel 2 side of the vehicle. This unsprung acceleration sensor 9 detects vibration acceleration in the upward and downward directions on the wheel 2 side which is a so-called unsprung side, and a detection signal thereof will be described later. To the controller 10.

  Reference numeral 10 denotes a controller composed of a microcomputer or the like. The controller 10 has an input side connected to the acceleration sensors 8 and 9 and the like, and an output side connected to the actuator 7 and the like of the shock absorber 6. The controller 10 has a storage unit 10A composed of a ROM, a RAM, and the like.

  In the storage unit 10A of the controller 10, the gain map 14 showing the relationship between the sprung speed V1 and the target damping force DF shown in FIG. 3, the target damping force DF, the relative speed V2 and the current value I shown in FIG. And a damping force map 15 showing the relationship between.

  Here, as shown in FIG. 2, the controller 10 includes integrators 11 and 12, a subtractor 13, a gain map 14, and a damping force map 15. Then, the integrator 11 of the controller 10 calculates a sprung speed V1 that is a speed in the upward and downward directions of the vehicle body 1 by integrating the detection signal from the sprung acceleration sensor 8. For this reason, the sprung acceleration sensor 8 and the integrator 11 constitute a vehicle body side vertical speed detector, and the integrator 11 outputs a sprung speed V1 that is the vehicle body side vertical speed.

  On the other hand, the subtractor 13 subtracts the detection signal from the unsprung acceleration sensor 9 from the detection signal from the sprung acceleration sensor 8, and calculates the difference between the sprung acceleration and the unsprung acceleration. At this time, this difference value corresponds to the relative acceleration between the vehicle body 1 and the wheel 2. Then, the integrator 12 integrates the relative acceleration output from the subtractor 13 and calculates the upward and downward relative speed V2 between the vehicle body 1 and the wheel 2. For this reason, the sprung acceleration sensor 8, the unsprung acceleration sensor 9, the subtractor 13 and the integrator 12 constitute a relative speed detector, and the integrator 12 outputs a relative speed V2.

  The gain map 14 constitutes a damping force calculation unit and outputs a target damping force DF to be generated by the shock absorber 6 based on the sprung speed V1. This target damping force DF is based on the target damping force obtained from the skyhook control theory and takes into account the later-described nonlinearity. Further, the gain map 14 has a nonlinear gain K shown in FIG. 3 as the target damping force shifting means. This nonlinear gain K converts the sprung speed V1 and outputs a target damping force DF, and changes the target damping force DF in real time according to the sprung speed V1.

  The target damping force DF increases or decreases in proportion to, for example, the sprung speed V1. However, when the sprung speed V1 is larger than the threshold value Vt (| V1 |> | Vt |), the sprung speed is smaller than the threshold value Vt (| V1 | <| Vt |). The change amount of the target damping force DF with respect to V1 is large.

  More specifically, when the sprung speed V1 is in the range from the negative threshold value (−Vt) to the positive threshold value Vt (−Vt ≦ V1 ≦ Vt), the slope of the nonlinear gain K ΔK1 is constant. On the other hand, when the sprung speed V1 toward the lower side is larger than the negative threshold value (−Vt) (V1 <−Vt), the slope ΔK2 of the nonlinear gain K is larger than the slope ΔK1. . Similarly, when the upward sprung speed V1 is higher than the positive threshold value Vt (V1> Vt), the slope ΔK3 of the nonlinear gain K is larger than the slope ΔK1.

  As described above, the non-linear gain K changes the slopes ΔK2, ΔK1, and ΔK3, which are proportional constants across the threshold values −Vt and Vt, and the target damping force DF changes non-linearly with respect to the sprung speed V1 as a whole. To do. Thus, the nonlinear gain K shifts the target damping force DF to the hard side when the magnitude (absolute value | V1 |) of the sprung speed V1 is larger than the threshold value Vt, and is smaller than the threshold value Vt. Sometimes the target damping force DF is shifted to the soft side.

  The magnitudes of the threshold values -Vt and Vt (absolute value | Vt |) are obtained as a result of intensive studies by the inventors, and are, for example, from 0.3 m / s to 0.6 m / s. And preferably between 0.45 m / s and 0.55 m / s (for example, | Vt | = 0.5 m / s). That is, when the sprung speed Va in which the feeling of stroke is a problem and the sprung speed Vb in which damping is a problem are examined, it is found that these values are different from each other. Specifically, the sprung speed Va at which the feeling of stroke is likely to affect the riding comfort is about 0.3 m / s, whereas the sprung speed Vb at which damping tends to decrease and vibration continues is 0.6 m / s. It was found that it was about s.

  Therefore, as shown in FIG. 5, the absolute values | Vt | of the threshold values −Vt and Vt are set to values between the sprung speeds Va and Vb (Va <| Vt | <Vb). As a result, when the sprung speed V1 is on the low speed side (| V1 | <| Vt |) where the stroke feeling becomes a problem, the target damping force DF is shifted to the soft side to improve the stroke feeling. On the other hand, when the sprung speed V1 is on the high speed side (| V1 |> | Vt |) where damping is a problem, the target damping force DF is shifted to the hard side to increase damping.

  The damping force map 15 constitutes an adjustment signal output unit, and outputs a current value I as an adjustment signal for adjusting the damping force characteristic of the shock absorber 6 based on the target damping force DF and the relative speed V2. As shown in FIG. 4, this damping force map 15 is set based on the test data by the inventors and the like in which the relationship between the target damping force DF and the current value I is variably set according to the relative speed V2. It is. The damping force map 15 outputs a current command value to be output to the actuator 7 of the shock absorber 6 as a current value I based on the target damping force DF from the gain map 14 and the relative speed V2 from the integrator 12. To do.

  Further, the damping force map 15 outputs an adjustment signal (current value I) for controlling the shock absorber 6 so that the damping force adjusting shock absorber is adapted to the Skyhook theory. More specifically, when the relative speed V2 is on the positive side (extension side), first, one is selected from a plurality of characteristic lines indicated by solid lines in FIG. 4 according to the magnitude of the relative speed V2. The In FIG. 4, the larger the relative speed V2, the more characteristic line on the right side. Next, the current value I corresponding to the value of the target damping force DF in the selected characteristic line is obtained. Geometrically, a line is drawn vertically from the value of the target damping force DF to obtain the intersection with the selected characteristic line, and the intersection between the line drawn horizontally from there and the vertical axis is the current value I.

  In this way, when the sprung speed V1 is on the positive side (upward side), the current value I is decreased as the target damping force DF increases, and the damping force characteristic is set to a hard characteristic (hard characteristic). When the sprung speed V1 is negative (downward), the current value I is constant at a large value regardless of the magnitude of the target damping force DF, and the damping force characteristic is set to a soft characteristic.

  On the other hand, when the relative speed V2 is on the negative side (contraction side), one is selected from a plurality of characteristic lines indicated by broken lines in FIG. 4 according to the magnitude of the relative speed V2. In FIG. 4, the larger the relative speed V2, the more the characteristic line on the left side. Next, the current value I corresponding to the value of the target damping force DF in the selected characteristic line is obtained.

  Thus, when the sprung speed V1 is on the positive side (upward side), the current value I is constant at a large value regardless of the magnitude of the target damping force DF, and the damping force characteristic is set to a soft characteristic. When the sprung speed V1 is on the negative side (downward side), the current value I is reduced as the target damping force DF becomes smaller (in the minus direction), and the damping force characteristic is set to a hard characteristic.

  As described above, the generated damping force of the shock absorber 6 is adjusted continuously between hardware and software according to the current value I supplied to the actuator 7 or variably in a plurality of stages.

  The vehicle suspension control measure according to the present embodiment has the above-described configuration. Next, a process for variably controlling the damping force characteristic of the shock absorber 6 using the controller 10 will be described.

  First, as shown in FIG. 1 and FIG. 2, when the vehicle travels, the controller 10 receives a detection signal of vibration acceleration in the upward and downward directions on the sprung (vehicle body 1) side from the sprung acceleration sensor 8. From the unsprung acceleration sensor 9, the detection signal of the vibration acceleration in the upward and downward directions on the unsprung (wheel 2) side is input.

  At this time, the integrator 11 provided in the controller 10 integrates the vibration acceleration detection signal from the sprung acceleration sensor 8, and calculates the upward and downward speeds of the vehicle body 1 as the sprung speed V1.

  On the other hand, the subtractor 13 provided in the controller 10 detects vibrations in the upper and lower directions on the vehicle body 1 side by the sprung acceleration sensor 8 and vibrations in the upper and lower directions on the wheel 2 side by the unsprung acceleration sensor 9. The relative acceleration between the vehicle body 1 and the wheel 2 is calculated by subtracting the acceleration detection signal. The integrator 12 integrates this relative acceleration to calculate an upward and downward relative speed V2 between the vehicle body 1 and the wheel 2.

  The sprung speed V1 output from the integrator 11 is input to the gain map 14 and converted into a target damping force DF as a skyhook gain using the nonlinear gain K. The nonlinear gain K changes the target damping force DF in real time according to the sprung speed V1, and increases the target damping force DF as the magnitude of the sprung speed V1 increases.

  Then, the target damping force DF output from the gain map 14 is input to the damping force map 15. The damping force map 15 outputs a current value I as an adjustment signal for adjusting the damping force characteristic of the shock absorber 6 based on the target damping force DF and the relative speed V2. At this time, the damping force map 15 controls the damping force characteristics of the shock absorber 6 based on the skyhook theory. Specifically, the damping force map 15 indicates the current value I as a current command value based on the magnitude and direction (upward and downward) of the sprung speed V1 and the magnitude and direction (elongation and contraction) of the relative speed V2. Ask. Thereby, the controller 10 supplies the electric current according to the electric current value I to the actuator 7 of the shock absorber 6, and variably adjusts the generated damping force of the shock absorber 6 between hardware and software.

  However, as shown in FIG. 6, in the control of the shock absorber 6, the stroke feeling and the damping have a trade-off relationship with respect to the magnitude of the gain of the target damping force DF. That is, when the gain of the target damping force DF is increased, the damping is improved while the feeling of stroke is deteriorated. On the other hand, when the gain of the target damping force DF is reduced, the feeling of stroke is improved, but the damping is deteriorated. For this reason, it is difficult to achieve both maintaining a sense of stroke and improving damping simply by increasing or decreasing the gain of the target damping force DF.

  On the other hand, in the present embodiment, when the magnitude of the sprung speed V1 is larger than the threshold value Vt, the amount of change in the target damping force DF with respect to the sprung speed V1 is larger when the magnitude of the sprung speed V1 is smaller than the threshold value Vt. It has become. Specifically, when the magnitude of the sprung speed V1 is greater than the threshold value Vt (| V1 |> | Vt |), the slopes ΔK2 and ΔK3 of the nonlinear gain K are such that the magnitude of the sprung speed V1 is greater than the threshold value Vt. Is also larger than the slope ΔK1 of the nonlinear gain K when (V1 | <| Vt |). For this reason, the non-linear gain K shifts the target damping force DF to the hard side when the magnitude of the sprung speed V1 is larger than the threshold value Vt, and the target damping when the magnitude of the sprung speed V1 is smaller than the threshold value Vt. Shift force DF to the soft side.

  Further, the threshold value Vt is set between the sprung speed Va where the stroke feeling is a problem and the sprung speed Vb where the damping is a problem. For this reason, as shown in FIG. 5, when the sprung speed V1 becomes smaller than the threshold value Vt and becomes the speed Va side, the nonlinear gain K decreases the change in the target damping force DF with respect to the sprung speed V1. . Thereby, the generated damping force of the shock absorber 6 can be suppressed and the stroke feeling can be improved.

  On the other hand, the non-linear gain K increases the amount of change in the target damping force DF with respect to the sprung speed V1 when the sprung speed V1 becomes larger than the threshold value Vt and becomes the speed Vb side. Thereby, the damping force generated by the shock absorber 6 can be greatly changed to increase the damping.

  Thus, in the present embodiment, the gain of the target damping force DF can be switched according to the sprung speed V1, and the gain of the target damping force DF can be reduced on the low speed side where the feeling of stroke is a problem. The gain of the target damping force DF can be increased on the high speed side where damping is a problem. As a result, in the present embodiment, as shown in FIG. 6, it is possible to achieve both maintenance of a feeling of stroke and improvement of damping.

  In order to explain the relationship between the sprung speed V1 and the target damping force DF according to the present embodiment, time changes of the sprung speed V1 and the target damping force DF are shown in FIG. Here, the two-dot chain line in FIG. 7 shows the time change of the target damping force DF according to the first comparative example. In the first comparative example, the gain (inclination) of the target damping force DF with respect to the sprung speed V1 is always set to a constant value (for example, the inclination ΔK1 in FIG. 3).

  In the case of the first comparative example, the gain of the target damping force DF is constant regardless of whether the sprung speed V1 is large or small. For this reason, when the gain of the target damping force DF is set giving priority to the stroke feeling, the stroke feeling is good, but when the sprung speed V1 is large, the control command corresponding to the target damping force DF becomes small and damping is performed. Becomes insufficient.

  Moreover, the broken line in FIG. 7 has shown the time change of the target damping force DF by the 2nd comparative example. In the second comparative example, when the sprung speed V1 increases beyond the threshold value, the target is maintained until the release condition is satisfied (for example, until a predetermined number of vibrations elapses). The case where the gain of the damping force DF is increased is shown.

  In the case of the second comparative example, in the state where the initial sprung speed V1 is small, the gain of the target damping force DF is small, so that the stroke feeling is improved. On the other hand, after the sprung speed V1 exceeds the threshold value, the gain of the target damping force DF increases until the release condition is satisfied. For this reason, in a state where the sprung speed V1 is high, damping (vibration suppression effect) is enhanced. However, even when the sprung speed V1 subsequently decreases, the control command corresponding to the target damping force DF increases, and the stroke feeling in this state is lost.

  Compared to these first and second comparative examples, in the present embodiment, the target damping force DF is applied only when the magnitude of the sprung speed V1 is larger than the threshold value Vt (| V1 |> | Vt |). When the gain is increased and smaller than the threshold value Vt (| V1 | <| Vt |), the gain of the target damping force DF is decreased. For this reason, it is possible to always maintain both a feeling of stroke and damping. In order to confirm such an effect, a simulation was performed for the present embodiment and the first comparative example when the vehicle traveled on a road surface having a large undulation and a small undulation. As a result, it was found that the damping can be improved by, for example, about 40% without deteriorating the acceleration of 3 to 6 Hz representing the feeling of stroke, as compared with the first comparative example.

  Thus, according to the present embodiment, the gain map 14 has a non-linear gain K, and when the sprung speed V1 is larger than the threshold value Vt, the sprung speed V1 becomes the threshold value Vt. In comparison with the case where the speed is smaller than the above, the change (gain) of the target damping force DF with respect to the sprung speed V1 is increased.

  For this reason, the nonlinear gain K reduces the gain of the target damping force DF when the sprung speed V1 is smaller than the threshold value Vt. Thereby, on the low speed side of the sprung speed V1 where the stroke feeling becomes a problem, the target damping force DF can be shifted to the soft side to maintain the stroke feeling.

  On the other hand, when the sprung speed V1 is larger than the threshold value Vt, the gain of the target damping force DF is increased. As a result, the damping can be enhanced by shifting the target damping force DF to the hard side on the high speed side of the sprung speed V1 where damping is a problem.

  As a result, the gain of the target damping force DF can be switched according to the sprung speed V1, and both the maintenance of the feeling of stroke and the improvement of damping can be achieved.

  Further, since the nonlinear gain K changes the target damping force DF in real time according to the sprung speed V1, even after the gain once increases, the gain decreases if the sprung speed V1 becomes smaller than the threshold value Vt. Can be made. For this reason, for example, as in the control device described in Patent Document 1, the stroke feeling at the low speed of the sprung speed V1 is lost compared to the case where a large gain is maintained until the release condition is satisfied after the gain once increases. It will not be lost. As a result, on the low speed side of the sprung speed V1 where the stroke feeling becomes a problem, it is possible to maintain the stroke feeling by always reducing the gain.

  Further, the threshold value Vt of the non-linear gain K is set to a value between the sprung speed Va at which the stroke feeling is a problem and the sprung speed Vb at which the damping is a problem. For this reason, depending on whether or not the sprung speed V1 is greater than the threshold value Vt, the gain of the target damping force DF can be changed with emphasis on the problematic characteristics of the stroke feeling and damping. Maintaining a feeling of stroke and improving damping can be achieved at the same time.

  In the above-described embodiment, the vehicle body side vertical speed detection unit is configured using the sprung acceleration sensor 8 and the integrator 11. However, the vehicle body 1 side upward and downward speeds (sprung speed V1) are directly measured. The vehicle body side vertical speed detection unit may be configured by using a sprung speed sensor that detects the speed of the vehicle.

  In the above-described embodiment, the relative speed detection unit is configured using the sprung acceleration sensor 8, the unsprung acceleration sensor 9, the subtractor 13, and the integrator 12. However, the sprung speed sensor, the unsprung speed sensor, and the subtraction are used. The relative speed detection unit may be configured using a device, or the relative speed detection unit may be configured using a speed sensor that directly detects the relative speed V2 between the vehicle body 1 and the wheel 2. The relative speed detection unit may be configured by a displacement sensor that detects the relative displacement between 1 and the wheel 2 and a differentiator.

  In the above embodiment, the nonlinear gain K is configured to switch the gain of the target damping force DF discontinuously depending on whether the magnitude of the sprung speed V1 is larger than the threshold value Vt. However, the present invention is not limited to this, and the nonlinear gain may be switched smoothly according to the magnitude of the sprung speed V1, for example, along a cubic curve. In this case, since the gain continuously changes, it is possible to reduce discontinuity due to control.

  In the above-described embodiment, the non-linear gain K is the magnitude of the threshold values Vt and -Vt (absolute value | Vt |) when the sprung speed V1 is positive (upward) and negative (downward). The threshold value Vt may be configured such that the sprung speed V1 differs between the positive side (upward side) and the negative side (downward side). Further, as values for determining the magnitudes of the threshold values Vt and -Vt, the sprung speed Va where the stroke feeling is a problem is 0.3 m / s, and the sprung speed Vb where the damping is a problem is 0.6 m / s. The case described above is described as an example. However, the present invention is not limited to this, and the sprung speeds Va and Vb are not limited to these numerical values, and are appropriately set according to the size and shape of the vehicle, the configuration of the suspension device, and the like.

  In the above-described embodiment, the case where the nonlinear gain K shown in FIG. 3 has a point-symmetric characteristic around the origin is described as an example. However, the present invention is not limited to this, and the non-linear gain may be configured such that the sprung speed V1 has different gains of the target damping force DF between the positive side (upward side) and the negative side (downward side). Further, in the above-described embodiment, the nonlinear gain K is not related to the relative speed V2, but the target damping force DF depends on whether the relative speed V2 is positive (extension side) or negative (contraction side). The gains may be different from each other.

  In the above-described embodiment, the single wheel 2 is schematically illustrated. However, for example, in the case of a four-wheeled vehicle, the present invention is applied independently to the suspension device 4 provided on each of the four wheels. Is. In this case, the non-linear gain may be different between the front wheel side and the rear wheel side.

  In the embodiment, the non-linear gain K is configured to output the target damping force DF proportional to the sprung speed V1 when the sprung speed V1 is smaller than or larger than the threshold value Vt. However, it may be configured to output a target damping force DF proportional to the sprung acceleration. However, since the phase of the sprung acceleration and the phase of the sprung speed are shifted, it is preferable to adjust the phase by a filter or the like.

  Furthermore, in the above-described embodiment, the case where the present invention is applied to the controller 10 that controls the shock absorber 6 of the suspension device 4 based on the Skyhook theory has been described as an example, but the controller that performs roll feedback control and pitch feedback control is described. It is good also as composition to apply.

DESCRIPTION OF SYMBOLS 1 Car body 2 Wheel 4 Suspension device 5 Spring 6 Damping force adjustment type shock absorber 7 Actuator 8 Sprung acceleration sensor 9 Unsprung acceleration sensor 10 Controller 11, 12 Integrator 13 Subtractor 14 Gain map (damping force calculation part)
15 Damping force map (adjustment signal output part)
K nonlinear gain

Claims (4)

In a vehicle suspension control apparatus including a damping force adjustment type shock absorber that is interposed between a vehicle body and wheels of a vehicle and that adjusts damping force characteristics using an adjustment signal,
A vehicle body side vertical speed detector that detects the vehicle body vertical speed as the vehicle body vertical speed, and the damping force adjustment type shock absorber is generated based on the vehicle body vertical speed by the vehicle body vertical speed detector. A damping force calculation unit that calculates a target damping force, a relative speed detection unit that detects an upper and lower relative speed between the vehicle body and the wheel, and a target damping force and the relative speed detection by the damping force calculation unit An adjustment signal output unit that outputs an adjustment signal for adjusting the damping force characteristic of the damping force adjusting shock absorber based on the relative speed by the unit;
The damping force calculation unit shifts the target damping force to the hard side when the vehicle body side vertical speed is larger than a predetermined threshold value, and the vehicle body side vertical speed is smaller than the threshold value. A vehicle suspension control apparatus characterized by comprising a target damping force shifting means for shifting the target damping force to the soft side sometimes. The target damping force shifting means is a non-linear gain that converts the vehicle body side vertical speed by the vehicle body side vertical speed detection unit and outputs the target damping force,
The non-linear gain is a change in the target damping force with respect to the vehicle body side vertical speed when the vehicle body side vertical speed is greater than the threshold value, compared to when the vehicle body side vertical speed is smaller than the threshold value. The suspension control device for a vehicle according to claim 1, wherein the minute amount is large.   3. The vehicle suspension control device according to claim 2, wherein the nonlinear gain changes the target damping force in real time according to a vehicle body side vertical speed by the vehicle body side vertical speed detection unit.   4. The vehicle according to claim 1, wherein the threshold value is set between a value at which a sense of stroke is a problem and a value at which damping is a problem in the vehicle body side vertical speed. Suspension control device.

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