JP2010195232A - Damping force control device and damping force control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain floating vibrations on a spring, which is an essential purpose of a sky hook control for improving stability of a vehicle, and as well as restrain a vertical jerk degree avoiding comfortability. <P>SOLUTION: A damping force of a damping force variable type shock absorber 1 provided between above and below a spring of a vehicle is controlled with a target value f<SB>dem</SB>for restraining a vertical speed on a spring as a target value. However, it is predicted that a jerk degree, which is a changing rate of vertical acceleration on the spring, exceeds a predetermined target jerk degree Jth, a damping force target value for restraining a vertical acceleration change on the spring to a vertical acceleration change of not more than the target jerk degree Jth. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is a damping force control technique for controlling a damping force generated by a variable damping force type shock absorber constituting a suspension.

As a conventional shock absorber control technique, for example, there is a technique described in Patent Document 1.
This technique controls the damping force generated by the shock absorber using the skyhook required damping force calculated by multiplying the skyhook damping coefficient and the absolute velocity on the spring as a damping force target value. The damping force is controlled by obtaining a target damping coefficient of the shock absorber corresponding to the damping force target value and adjusting the damping force of the shock absorber so as to be the target damping coefficient.

  Further, the target attenuation coefficient is limited by using one value of the vertical acceleration detected by the vertical acceleration detecting means or the change rate of the vertical acceleration. That is, when the one value exceeds a threshold set in advance in a stepwise manner, the target attenuation coefficient is corrected in a stepwise manner according to the magnitude. With this processing, the conventional technology aims to suppress the vertical jump.

JP-A-7-304315

In the above prior art, the damping coefficient of the shock absorber is excessively reduced, and the fluffy vibration on the spring, which is the original purpose of the skyhook control law, may increase.
The present invention pays attention to the above points, and suppresses fluffy vibration on the spring, which is the original purpose of the skyhook control law for improving the stability of the vehicle, and the vertical jump that inhibits comfort. An object of the present invention is a damping force control technique capable of achieving both suppression.

  In order to solve the above-mentioned problems, the present invention targets a damping force target value that suppresses the vertical speed on the spring, and the damping force of the damping force variable shock absorber interposed between the sprung and unsprung parts of the vehicle. Control as a value. However, if the jerk, which is the rate of change of vertical acceleration on the spring, is predicted to exceed a predetermined target jerk, the damping force target value that suppresses the vertical acceleration change on the spring is separately added to the vertical acceleration change below the target jerk. Calculate to obtain the target value.

  According to the present invention, it is possible to suppress fluffy vibration on a spring while suppressing a change in vertical acceleration on the spring from exceeding a target jerk. That is, it is possible to achieve both the suppression of fluffy vibration on the spring, which is the original purpose of the skyhook control law for improving the stability of the vehicle, and the suppression of the vertical jump that impairs comfort.

It is a schematic diagram explaining the apparatus structure which concerns on embodiment based on this invention. It is a figure which shows the model of each vehicle wheel which concerns on embodiment based on this invention. It is a figure which shows the structure and flow of the absorber controller which concerns on embodiment based on this invention. It is a figure which shows the road surface displacement input example. It is a figure which illustrates the vertical displacement on the spring of a comparison. It is a figure which illustrates the up-and-down jump degree on a comparison spring. It is a figure which illustrates the up-and-down displacement on the spring in this embodiment. It is a figure which illustrates the up-and-down jump degree on a spring in this embodiment. It is an example of a time chart of a damping force command signal in a comparative example. It is an example of a time chart of a damping force command signal in the present embodiment. It is a figure which shows the log | history of the damping force with respect to stroke speed. It is a figure which shows the positional relationship of a comparative example and this embodiment in the two-dimensional plane centering on a vertical jump degree and a vertical displacement. It is a figure which shows the setting of the target jerk according to 2nd Embodiment based on this invention. It is a figure which shows the setting of the target jerk according to 3rd Embodiment based on this invention. It is a figure which shows the setting of the target jerk according to 4th Embodiment based on this invention. It is a figure which shows the setting of the target jerk which concerns on 5th Embodiment based on this invention.

Next, embodiments of the present invention will be described with reference to the drawings.
The shock absorber 1 constituting a part of the suspension device is arranged for each wheel.
As shown in FIG. 1, each shock absorber 1 is interposed between a sprung and unsprung portion of the vehicle. That is, each shock absorber 1 is interposed between the corresponding wheel 2 and the vehicle body 3. Specifically, the lower end portion of the shock absorber 1 is connected to the wheel 2 or a suspension link that connects the wheel 2 and the vehicle body 3. The upper end of the shock absorber 1 is connected to the vehicle body 3.

  The shock absorber 1 is a variable damping force type shock absorber. That is, the shock absorber 1 includes an actuator 4 for changing the damping force by changing the size of the orifice. The actuator 4 is configured by, for example, a rotary solenoid or the like and rotationally displaces a control shaft disposed in the shock absorber 1 to change the damping force. The actuator 4 adjusts the amount of rotational displacement according to a command from the absorber controller 5.

A suspension spring 6 is arranged together with the shock absorber 1.
Further, a sprung vertical acceleration sensor 7 is provided on the vehicle body 3 in the vicinity of the shock absorber 1 as a target in plan view. The sprung vertical acceleration sensor 7 detects the vertical acceleration on the spring and outputs a detection signal to the absorber controller 5. The set position of the vertical acceleration sensor 7 for the sprung is a position close to the target shock absorber 1 in plan view.

Further, an unsprung vertical acceleration sensor 8 is provided on the wheel 2 side. The unsprung vertical acceleration sensor 8 detects the unsprung vertical acceleration and outputs a detection signal to the absorber controller 5.
Here, FIG. 2 shows a model of each vehicle wheel of the present embodiment. x0 indicates the vertical displacement of the road surface. x1 represents the unsprung displacement. x2 indicates the displacement on the spring.
In the following description, “′” represents a single differentiation. “″” Represents a second derivative.

Next, the absorber controller 5 of this embodiment will be described.
As shown in the figure, the absorber controller 5 includes an integrating means 5A, a restoring force calculating unit 5B, a skyhook required damping force calculating unit 5C, a jerk predicted value calculating unit 5D, a target jerk setting unit 5E, and a jerk threshold determination. Unit 5F, acceleration target value calculation unit 5G, required damping force update unit 5H, and required damping force output unit 5J.
The integrating means 5A includes a sprung vertical speed calculator 5Aa, an unsprung vertical speed calculator 5Ab, a stroke speed calculator 5Ac, and a stroke calculator 5Ad.

The sprung vertical speed calculation unit 5Aa calculates the vertical speed x2 'on the spring by integrating the vertical acceleration detected by the vertical acceleration sensor 7 for the spring.
The unsprung vertical speed calculator 5Ab calculates the unsprung vertical speed x1 'by integrating the vertical acceleration detected by the unsprung vertical acceleration sensor 8.
The stroke speed calculation unit 5Ac calculates the suspension stroke speed (x2′−x1 ′) from the deviations of the vertical and vertical spring speeds calculated by the sprung vertical speed calculation unit 5Aa and the sprung vertical speed calculation unit 5Aa. Is calculated.
The stroke calculation unit 5Ad calculates the suspension stroke amount (x2-x1) by integrating the stroke speed calculated by the stroke speed calculation unit 5Ac.

  Here, the stroke amount and the stroke speed may be obtained as follows. That is, a stroke detecting means for detecting the vertical stroke of the suspension is provided. The stroke detection sensor detects the vertical stroke amount of the wheel 2 relative to the vehicle body 3 and outputs a detection signal to the absorber controller 5. The vertical stroke amount can be obtained by detecting the vertical swing angle of the suspension link and the stroke amount of the shock absorber 1. The stroke amount of the suspension is calculated by this stroke detection means. Further, the stroke speed is calculated by differentiating the stroke amount.

The restoring force calculator 5B calculates the restoring force component f _ks by multiplying the stroke amount by the spring constant K1, as in the following equation. When the restoring force component f _ks is not linear with respect to the stroke amount, a function or map is used to calculate the restoring force component f _ks using the stroke amount as a parameter.
f _ks = K1 × (x2−x1)

Next, the skyhook required damping force calculation unit 5C calculates the skyhook required damping force based on the skyhook control law. That is, the skyhook required damping force calculation unit 5C calculates a damping force target value that suppresses the vertical speed on the spring.
Specifically, as shown in the following equation, the skyhook required damping force f _dem is calculated by multiplying the vertical speed on the spring by the skyhook damping coefficient Csky.
f _dem = Csky × x2 ′ (t)

Further, the jerk predicted value calculation unit 5D calculates a jerk predicted value.
The jerk predicted value calculation unit 5D first calculates the vertical acceleration x2 ″ ^* predicted to be generated on the spring by the skyhook request damping force f _dem calculated by the skyhook request damping force calculation unit 5C. Here, in this embodiment, the predicted vertical acceleration x2 ″ ^* is calculated in consideration of the restoring force component f _ks .
x2 ″ ^* (t) =-(F _dem + f _ks ) / m2

Next, the jerk predicted value calculation unit 5D uses the vertical acceleration x2 ″ (t−1) on the spring acquired from the vertical acceleration sensor 7 one control cycle before, and based on the following formula, the jerk J ( t) is calculated.
J (t) = {x2 " * (t) -x2" (t-1)} / τ
Here, τ is a control sampling time.

  The target jerk setting unit 5E sets the target jerk Jth according to the vehicle characteristics of the target vehicle. The vehicle characteristics are characteristics according to weighting of comfort with respect to safety using safety and comfort as indices. The target jerk Jth may be a fixed value based on safety and comfort required for the vehicle. Further, as exemplified in the second and subsequent embodiments, the setting may be changed by weighting safety and comfort according to the running state such as vehicle behavior. The driving state using the weighting of comfort for safety as an index can be estimated from the behavior of the vehicle and the driving operation.

The jerk threshold determination unit 5F determines whether or not the absolute value of the jerk calculated by the jerk predicted value calculation unit 5D is larger than the target jerk Jth. That is, jerk threshold value determination unit 5F selects a damping force target value to be selected. When the absolute value of the jerk J (t) is equal to or less than the target jerk Jth, information to that effect, that is, information to select the skyhook requested damping force f _dem is output to the requested damping force output unit 5J. To do. The jerk J (t) is the jerk in the vertical direction on the spring that is predicted to occur.

On the other hand, when the absolute value of the jerk J (t) is larger than the target jerk Jth, an activation command is output to the acceleration target value calculator 5G.
The acceleration target value calculation unit 5G calculates the acceleration target value x2 ″ ^* (t) based on the following equation.
x2 ″ ^* (t) = x2 ″ (t−1) + sign (J (t)) × Jth · τ
Here, τ is a control sampling time.
The acceleration target value x2 ^"* (t) is one control cycle before the vertical acceleration x2" acceleration increment from (t-1), is obtained by limiting the target jerk Jth equivalent.
The required damping force update unit 5H calculates the second required damping force f _dem2 to be the acceleration target value x2 ″ ^* (t) calculated by the acceleration target value calculation unit 5G by the following equation. In the equation, the second required damping force f _dem2 is calculated in consideration of the restoring force component f _ks .
f _dem2 = −x2 ″ ^* (t) × m2−f _ks

Based on the determination by the jerk threshold determination unit 5F, the required damping force output unit 5J determines the Skyhook requested damping force f _dem as the damping force target when the absolute value of the jerk J (t) is equal to or less than the target jerk Jth. Select as value. When the absolute value of the jerk J (t) exceeds the target jerk Jth, the second required damping force f _dem2 is selected as the damping force target value.
Then, a command value corresponding to the selected damping force target value is output to the actuator 4.
As described above, the damping force control is performed for each shock absorber 1 of each wheel.

(Operation / Action)
The following damping force control is performed for each shock absorber 1 of each wheel.
The absorber controller 5 that performs the damping force control operates every predetermined sampling period, and calculates the skyhook required damping force f _dem for suppressing the displacement on the spring from the vertical speed x2 ′ (t) on the spring.
The jerk J is predicted on the basis of the predicted acceleration that is predicted to be generated when the calculated skyhook required damping force f _dem is attenuated. In the present embodiment, the restoring force component f _ks is also considered in order to improve the accuracy of the jerk predicted value.

When the predicted jerk J is equal to or less than the target jerk Jth, the calculated skyhook required damping force f _dem is selected as the damping force target value.
On the other hand, the jerk J predicted when that caused the damping force in the skyhook required damping force f _dem is, it is determined to be larger than the target jerk Jth, the second required damping force f _DEM2 as a damping force target value select.
The second required damping force f _dem2 is a required damping force that limits the jerk that will occur to a target jerk Jth or less.

The second required damping force f _dem2 is calculated as follows.
First, the acceleration target value x2 to limit the amount of change of acceleration in the target jerk Jth corresponding "calculates the ^* (t). Then, the target acceleration value x2" damping force to achieve ^* (t) second The required damping force f _{dem2 is} assumed. In the present embodiment, the second required damping force f _dem2 is calculated in consideration of the restoring force component f _ks .
Thus, when it is determined that the predicted jerk is greater than the target jerk Jth, the damping force target value is limited so that the jerk that will occur is equal to or less than the target jerk Jth.

  Thus, when the vertical jerk is equal to or less than the target jerk Jth, the fluffy vibration on the target spring is suppressed by the original control of the Skyhook control law for improving the stability of the vehicle. On the other hand, if the vertical jerk is predicted to exceed the target jerk Jth, the occurrence of a large vertical jerk that inhibits comfort is suppressed. As a result, it is possible to achieve both suppression of fluffy vibration on the spring and suppression of a large vertical jump that impairs comfort.

The above operation will be further described.
Here, four types of damping modes are considered as the damping force of the shock absorber 1. The four types of attenuation modes are a soft mode A, a hard mode B, a comparison control mode C with only skyhook control, and an embodiment mode D employing the control of the above-described embodiment.
The soft mode A is a case where the damping force of the shock absorber 1 is fixed with a low damping force.
The hard mode B is a case where the damping force of the shock absorber 1 is fixed with a low damping force.
The comparison control mode C is a case where the damping force control is performed with the above-described skyhook required damping force always set as the damping force mode.
The embodiment mode D is a case where the damping force control that selectively uses the skyhook required damping force f _dem and the second required damping force f _dem2 is performed as described above.

  For example, a case is assumed where a vehicle having a sprung eigenvalue of 1.2 Hz travels on a road surface of 1.2 Hz ± 30 mm as shown in FIG. In this case, the sprung eigenvalue matches the road surface input frequency. At this time, in the case of the soft mode A, the displacement on the spring tends to diverge as indicated by the symbol A in FIG. On the other hand, when the hard mode B is employed to suppress the displacement on the spring, the displacement on the spring is suppressed as indicated by B in FIG. However, in the hard mode B, when the vehicle enters the road surface, the up-and-down jump rate increases and the user feels uncomfortable.

  Further, when the comparison control mode C (skyhook control) is applied to suppress the displacement on the spring, the displacement on the spring can be further suppressed as indicated by C in FIG. However, in the comparison control mode C, the damping force target value changes suddenly when the road surface is turned up or down. That is, since the damping force is suddenly switched between the hard mode B and the soft mode A, as shown in FIG. Such a discomfort is given to the occupant.

On the other hand, in the embodiment mode D, as shown in FIG. 7, the suppression of the displacement on the spring can be suppressed to the same extent as in the comparison control mode C. Further, even when looking at the vertical jerk on the spring, as shown in FIG. 8, the vertical jerk can be suppressed to the target jerk Jth or less. In this analysis example, the target jerk Jth is set to 50 m / s ³ .
FIG. 9 shows a history of the damping force command value in the comparison control mode C. FIG. 10 shows a history of damping force command values in the embodiment mode D.
As can be seen from FIGS. 9 and 10, by adopting the embodiment mode D, the change in the damping force command value is corrected in a direction that is smoother than in the comparative control mode C. For this reason, as shown in FIG. 11, by adopting this embodiment, the use damping force also shows a more continuous and smooth change compared to the case of only the skyhook control.

FIG. 12 shows the correlation between the vertical displacement on the spring and the jerk in the vertical direction, which summarizes the above.
As shown in FIG. 12, by adopting this embodiment, the sprung displacement equivalent to the skyhook control and the vertical jerk like the soft mode A are achieved, and both the displacement restraint on the spring and the jerk are suppressed. It becomes possible.
Here, the skyhook required damping force calculation unit 5C constitutes a first damping force target value calculation unit. The target jerk setting unit 5E constitutes a target jerk setting means. The acceleration target value calculation unit 5G and the required damping force update unit 5H constitute second damping force target value calculation means. The jerk predicted value calculation unit 5D constitutes a jerk calculation means. The jerk threshold determination unit 5F constitutes a damping force target value selection unit. The actuator 4 constitutes damping force control means. The required damping force update unit 5H constitutes a damping force target value correcting unit.

(Effect of this embodiment)
(1) The first damping force target value calculation means calculates a damping force target value f _dem that suppresses the vertical speed on the spring. The target jerk setting means sets a target jerk Jth which is a value related to the rate of change in vertical acceleration. The second damping force target value calculating means, the damping force target value to suppress the vertical acceleration variation on spring vertical acceleration change follows the target jerk Jth calculates f _DEM2. The jerk calculation means calculates the jerk J that is predicted to occur at the rate of change of the vertical acceleration on the spring. When the damping force target value selection means determines that the jerk J calculated by the jerk calculation means exceeds the target jerk Jth, the damping force target value selection means selects the damping force target value calculated by the second damping force target value calculation means, and the jerk When the jerk calculated by the calculating means is equal to or less than the target jerk Jth, the damping force target value calculated by the first damping force target value calculating means is selected. The damping force control unit controls the damping force of the variable damping force shock absorber 1 using the damping force target value selected by the damping force target value selecting unit as a target value.
While suppressing the change in the vertical acceleration on the spring from exceeding the target jerk Jth, fluffy vibration on the spring can be suppressed. That is, it is possible to achieve both the suppression of fluffy vibration on the spring, which is the original purpose of the skyhook control law for improving the stability of the vehicle, and the suppression of the vertical jump that impairs comfort.

(2) The restoring force acquisition means acquires a restoring force component f _ks between the sprung and unsprung portions of the vehicle. The damping force target value correcting means corrects the damping force target value f _dem2 calculated by the second damping force target value calculating means with the restoring force component f _ks acquired by the restoring force acquisition means.
By obtaining the damping force target value f _dem2 calculated by the second damping force target value calculation means in consideration of the restoring force component, the damping force can be reduced as in the case of the bottom of the suspension, etc. even if the acceleration change is suppressed. It can be applied when the up / down jump rate can be suppressed more by raising it.

(3) The jerk calculation means calculates the jerk from the vertical acceleration predicted to be generated on the spring by the damping force target value f _dem calculated by the first damping force target value calculation means and the past vertical acceleration information. J is calculated.
As a result, before the change in vertical acceleration on the spring exceeds the target jerk Jth, the damping force calculated by the second damping force target value calculation means from the damping force target value f _dem calculated by the first damping force target value calculation means. The force target value f _dem2 can be switched. Thus, it is possible to suppress the change in vertical acceleration on the spring from exceeding the target jerk Jth.

(Second Embodiment)
Next, a second embodiment will be described with reference to the drawings. The same components as those in the first embodiment will be described with the same reference numerals.
The basic configuration of this embodiment is the same as that of the first embodiment. However, the target jerk setting unit 5E is different.
The target jerk setting unit 5E of the present embodiment sets and changes the target jerk Jth based on at least one of the vehicle running state and the driving operation.
Other configurations are the same as those in the first embodiment.
Here, the vehicle on which the present embodiment is based is configured to be able to select a plurality of travel modes. The plurality of travel modes are a normal mode, a sports mode, and a comfort mode.

In the plurality of travel modes, the comfort index and stability are set by weighting the index. That is, the normal mode is used as a reference. The Sports mode is a travel mode in which the weight on the stability side is larger than that in the normal mode. The Comfort mode is a traveling mode in which the weighting of comfort is larger than that in the normal mode.
And the mode selection switch 20 which selects one of the said driving modes by a driver | operator's operation is provided. The initial value of the running mode is the normal mode.
Moreover, the vehicle speed sensor which detects a vehicle speed is provided. The vehicle speed sensor 21 detects the vehicle speed based on wheel speed or the like.
The target jerk setting unit 5E acquires the vehicle speed and the selected travel mode, and changes the target jerk Jth according to the vehicle speed and the selected travel mode.

  Specifically, based on a map as shown in FIG. 13, the target jerk Jth is increased when the vehicle speed is high compared to when the vehicle speed is low. In the driving mode in which the stability weight is greater than the comfort, the value of the target jerk Jth is increased compared to the driving mode in which the comfort weight is greater than the stability. That is, the value of the target jerk Jth is made smaller when the Comfort mode is selected than when the normal mode is selected. Further, the value of the target jerk Jth is increased when the Sports mode is selected than when the Normal mode is selected.

Here, the target jerk Jth may be set and changed continuously with the values on the line shown in FIG. 13 as variables of the vehicle speed and the travel mode. Alternatively, a value indicated by a circle in the figure may be set as the target jerk Jth, and the target jerk Jth may be set and changed step by step according to the vehicle speed. The same applies to other embodiments.
Further, when the selected travel mode is the Comfort mode, when the vehicle speed is low, the increase in the target jerk Jth associated with the increase in speed is suppressed, and when the vehicle speed exceeds a predetermined value, the target jump associated with the increase in speed is achieved. Increase the degree of Jth.
On the other hand, when the selected driving mode is the Sports mode, when the vehicle speed is low, the target jerk Jth increase with the increase in speed is increased, and when the vehicle speed exceeds a predetermined value, the target with the increase in speed is increased. Suppress the increment of jerk Jth.

(Operation / Action)
When the vehicle is running, the soft mode A having a low damping force has a small jerk, but the displacement on the spring is large, and the occupant feels the magnitude of the behavior as visual information and gives anxiety. Further, since the occupant is greatly displaced along with the magnitude of the displacement on the spring, the relative displacement between the occupant and the vehicle body 3 is increased, which may be a cause of hindering the driving operation. Therefore, in order to achieve both safety and security, ensuring the stability of the vehicle in a driving state where the vehicle speed is high leads to a sense of security for the occupant.

On the other hand, in a running state where the vehicle speed is low, there are few scenes where the displacement on the spring is large, and comfort such as smooth running is emphasized.
In order to achieve both comfort and a sense of security depending on the vehicle speed range, it is necessary to give weight to stability at high speeds and weight to comfort at low speeds.
In view of the above, in the present embodiment, the target jerk Jth is changed according to the vehicle speed as described above.

  Further, when selecting the Sports mode, the occupant expects more stability than comfort. Also, when selecting the Comfort mode, comfort is expected rather than stability. In order to realize these expectations by the vehicle, when the Sports mode is selected, in order to further improve the stability of the vehicle, and when the Comfort mode is selected, in order to improve the comfort, the target is set according to the driving mode. Change the jerk Jth.

(Effect of this embodiment)
(1) The target jerk setting means estimates the required comfort and stability weighting based on at least one of the vehicle running state and driving operation, and changes the target jerk Jth based on the estimation.
As a result, it is possible to set an appropriate target jerk Jth according to the running state of the vehicle and the driving operation.
(2) The target jerk setting means changes the target jerk Jth according to the vehicle speed, and increases the value of the target jerk Jth when the vehicle speed is high compared to when the vehicle speed is low.
It is possible to ensure the stability of the vehicle in a traveling state where the vehicle speed is high, and to ensure comfort such as smooth running in a traveling state where the vehicle speed is low.

(3) The target jerk setting means changes the setting of the target jerk Jth according to the driving mode selected by the driving mode selection means, and in the case of the driving mode in which the stability weight is greater than the comfort, The target jerk Jth is increased as compared with the driving mode in which the comfort weight is large.
It becomes possible to set the target jerk Jth according to the vehicle characteristics in the travel mode.

(Modification)
(1) In the above description, the case where the target jerk Jth is set with both the vehicle speed and the travel mode as variables is illustrated. The target jerk Jth may be set and changed only from the vehicle speed. Further, the target jerk Jth may be set and changed only from the running mode.
(2) The target jerk Jth is set and changed by weighting comfort and stability. It may be predicted whether priority is given to comfort or stability from other vehicle behavior information or driving operation, and the target jerk Jth may be set and changed by the prediction.

(Third embodiment)
Next, a third embodiment will be described with reference to the drawings. The same components as those in the above embodiments will be described with the same reference numerals.
The basic configuration of this embodiment is the same as that of the first embodiment. However, the target jerk setting unit 5E is different.
The vehicle as a premise of the present embodiment includes a steering angle sensor 22. The steering angle sensor 22 detects the steering angle of the steering wheel.
And the target jerk setting part 5E of this embodiment sets and changes the target jerk Jth based on driving operation. That is, in the target jerk setting unit 5E of the present embodiment, the target jerk Jth is set and changed according to information on the steering angle of the steering wheel operated by the driver. Specifically, using the map shown in FIG. 14, when the steering angle or the steering angular velocity is large, the value of the target jerk Jth is made larger than when the steering angle or the steering angular velocity is small.
Other configurations are the same as those in the first embodiment.

(Operation / Action)
At the time of steering, the occupant's body is shaken by the rolling behavior of the vehicle, etc., which contributes to hindering the driving operation, and the safety is lowered. Therefore, the stability of the vehicle is further required. On the other hand, when driving straight ahead, more comfort is required because the driver cannot be distracted.
Considering this, as described above, the vehicle behavior is weighted during steering and during straight running based on the information of the steering angle. In other words, in order to discriminate between steering and straight traveling from the steering information and to give weight to the vehicle behavior between safety and comfort, the jerk target value is set according to the steering angular velocity or the steering angle. Change.

(Effect of this embodiment)
(1) The target jerk setting means changes the setting of the target jerk Jth according to the steering angle or the steering angular speed of the steering wheel. The target jerk Jth is increased.
Both safety during steering and comfort during straight travel can be ensured.

(Fourth embodiment)
Next, a fourth embodiment will be described with reference to the drawings. The same components as those in the above embodiments will be described with the same reference numerals.
The basic configuration of this embodiment is the same as that of the first embodiment. However, the target jerk setting unit 5E is different.
The vehicle as a premise of the present embodiment includes an accelerator opening sensor 23 that detects an accelerator opening, and a hydraulic pressure sensor 24 that detects a brake hydraulic pressure.
Then, the target jerk setting unit 5E of this embodiment changes the setting of the target jerk Jth according to the acceleration / deceleration generated in the vehicle. When the absolute value of the acceleration / deceleration is large, the absolute value of the acceleration / deceleration is small. In comparison, the target jerk Jth is increased. Specifically, the acceleration is estimated from the accelerator opening. Further, the deceleration is estimated based on the hydraulic pressure detected by the hydraulic pressure sensor 24.

Then, using the map shown in FIG. 15, the target jerk Jth is calculated using at least one of the accelerator opening and the brake hydraulic pressure. For example, when the accelerator pedal is depressed, the target jerk Jth is set and changed depending on the accelerator opening. When the brake pedal is depressed, the target jerk Jth is changed according to the brake fluid pressure.
Other configurations are the same as those in the first embodiment.

(Operation / Action)
During acceleration / deceleration, pitching occurs in the vehicle. In the pitching, the occupant feels the visual information of the sprung displacement and gives anxiety. In addition, because the ground contact load of the front and rear wheels fluctuates greatly as a vehicle characteristic, the steering balance of the front and rear wheels fluctuates when turning, etc. Is required.
On the other hand, when traveling at a constant speed, the occupant is less likely to concentrate on the operation, and the rider feels comfortable and comfortable. Therefore, different weights are required for vehicle behavior depending on the stability during acceleration / deceleration and the comfort during traveling at a constant speed.
Considering the above, the vehicle characteristics are changed by changing the target jerk Jth according to the two scenes. Therefore, the jerk target value is changed according to the accelerator opening and the brake fluid pressure.

(Effect of this embodiment)
(1) The target jerk setting means changes the target jerk Jth according to the acceleration / deceleration generated in the vehicle. When the absolute value of the acceleration / deceleration is large, the target jerk Jth is set compared with Increase the value of jerk Jth.
It is possible to ensure stability during acceleration / deceleration and comfort during constant speed driving.
(Modification)
In the above embodiment, the degree of acceleration / deceleration is estimated based on the accelerator opening and the brake fluid pressure. However, it is not limited to this.
The acceleration / deceleration itself may be directly detected, and the target jerk Jth may be set to increase as the absolute value of the acceleration / deceleration increases.

(Fifth embodiment)
Next, a fifth embodiment will be described with reference to the drawings. The same components as those in the above embodiments will be described with the same reference numerals.
The basic configuration of this embodiment is the same as that of the first embodiment. However, the target jerk setting unit 5E is different.
In the present embodiment, the target jerk setting unit 5E, as shown in FIG. 16, sets the target jerk Jth for the front-wheel-side damping force variable shock absorber 1 to the target-wheel jerk for the rear-wheel-side damping force variable shock absorber 1. Set larger than jerk Jth.
Other configurations are the same as those in the first embodiment.

(Operation / Action)
Since the passengers in the front seat concentrate on driving operations and the surrounding environment of the vehicle, more vehicle stability is required. On the other hand, the passenger in the rear seat does not need to perform a driving operation, and more vehicle comfort is required. Thus, the weight required for stability and comfort differs depending on the position of the occupant even in the same vehicle. However, since the occupant is on the same spring, it is difficult to achieve both stability and comfort. In order to eliminate this trade-off, different jerk target values are set for the front suspension and the rear suspension for the purpose of ensuring the comfort of the rear seat occupant sitting near the axle.

(Effect of this embodiment)
(1) The target jerk setting means sets the target jerk Jth for the front wheel side damping force variable shock absorber 1 to be larger than the target jerk Jth for the rear wheel variable damping force shock absorber 1.
This makes it possible to ensure stability for the front seat occupant, particularly the driver, and comfort for the rear seat occupant.

DESCRIPTION OF SYMBOLS 1 Shock absorber 2 Wheel 4 Actuator 5 Absorber controller 5A Integration means 5Aa Unsprung vertical speed calculating part 5Ab Unsprung vertical speed calculating part 5Ac Stroke speed calculating part 5Ad Stroke calculating part 5B Restoring force calculating part 5C Skyhook required damping force calculating part 5D Expected jerk calculation unit 5E Target jerk setting unit 5F Jug threshold value determination unit 5G Target acceleration value calculation unit 5H Required damping force update unit 5J Required damping force output unit 6 Suspension spring 7 Lower acceleration sensor for spring 8 Unsprung Vertical acceleration sensor 20 Mode selection switch 21 Vehicle speed sensor 22 Steering angle sensor 23 Accelerator opening sensor 24 Hydraulic pressure sensor Csky Skyhook damping coefficient f _dem Skyhook required damping force (damping force target value)
f _dem2 damping force target value (damping force target value)
f _ks restoring force component J predicted jerk Jth target jerk

Claims (10)

A damping force control device for controlling a damping force generated by a damping force variable shock absorber interposed between a sprung and an unsprung portion of a vehicle,
First damping force target value calculating means for calculating a damping force target value for suppressing the vertical speed on the spring;
Target jerk setting means for setting a target jerk that is a value related to the rate of change in vertical acceleration;
Second damping force target value calculating means for calculating a damping force target value that suppresses the vertical acceleration change on the spring to the vertical acceleration change below the target jerk,
The jerk calculating means for calculating the jerk predicted to be generated from the vertical acceleration predicted to be generated on the spring by the damping force target value calculated by the first damping force target value calculating means and the past vertical acceleration information. When,
If it is determined that the jerk calculated by the jerk calculating means exceeds the target jerk, the damping force target value calculated by the second damping force target value calculating means is selected, and the jerk calculated by the jerk calculating means is the target jump. Damping force target value selection means for selecting the damping force target value calculated by the first damping force target value calculation means when the degree is less than or equal to the degree;
Damping force control means for controlling the damping force of the variable damping force shock absorber with the damping force target value selected by the damping force target value selection means as a target value;
A damping force control device comprising: Restoring force acquisition means for acquiring a restoring force component between the sprung and unsprung portions of the vehicle;
Damping force target value correcting means for correcting the damping force target value calculated by the second damping force target value calculating means with the restoring force component acquired by the restoring force acquiring means;
The damping force control apparatus according to claim 1, further comprising:   The target jerk setting means is configured to estimate a required comfort and stability weighting based on at least one of a driving state and a driving operation of the vehicle, and to set and change the target jerk based on the estimation. A damping force control device according to claim 1 or 2.   The target jerk setting means changes the setting of the target jerk according to the vehicle speed, and increases the value of the target jerk when the vehicle speed is high compared to when the vehicle speed is low. The damping force control device described. A driving mode selection means for a driver to select a driving mode from a plurality of driving modes with comfort and stability as indices,
The target jerk setting means changes the target jerk according to the driving mode selected by the driving mode selection means, and in the driving mode in which the stability weight is greater than the comfort, the comfort jerk than the stability is set. The damping force control device according to claim 3 or 4, wherein a value of the target jerk is increased as compared with a traveling mode having a large weight.   The target jerk setting means changes the target jerk according to the steering angle or steering angular speed of the steering wheel, and when the steering angle or steering angular speed is large, the target jerk is smaller than when the steering angle or steering angular speed is small. The damping force control device according to any one of claims 3 to 5, wherein the value of is increased.   The target jerk setting means changes the target jerk according to the acceleration / deceleration generated in the vehicle. When the absolute value of acceleration / deceleration is large, the target jerk value is smaller than when the absolute value of acceleration / deceleration is small. The damping force control device according to any one of claims 3 to 6, wherein the damping force control device is increased.   The target jerk setting means sets the target jerk for the front wheel side damping force variable shock absorber larger than the target jerk for the rear wheel variable damping force shock absorber. The damping force control apparatus according to claim 7. Control the damping force of the variable damping force shock absorber interposed between the sprung and unsprung parts of the vehicle with the damping force target value that suppresses the vertical speed on the spring as the target value.
If the jerk, which is the rate of change of vertical acceleration on the spring, is predicted to exceed a predetermined target jerk, the damping force target value that suppresses the vertical acceleration change on the spring to the vertical acceleration change below the target jerk is the target value The damping force control method characterized by controlling as follows.   Using comfort and stability as an index, if the driving condition with higher safety weight than comfort is determined, the above target jerk should be set larger than the driving condition with higher comfort weighting than safety. A damping force control method according to claim 9.

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