KR0142974B1 - Suspension control device - Google Patents

Abstract

When the noise level such as road noise transmitted to the vehicle interior is small, the operation noise evaluation of the step motor is improved to provide a control device for the damping force variable shock absorber in which it is not caught as an abnormal sound.

When the vehicle speed detection value V is less than or equal to the predetermined vehicle speed value V ₀ with a low noise level such as road noise, the hold time when the current position P _A of the step motor matches the target position P _D is increased or By increasing the set time when the rotation direction is changed and forcibly setting the step amount S which is the rotation control signal of the step motor during the hold time or the set time to zero, the rotation drive time having a large vibration level is compared. It is designed to shorten or to reduce the number of occurrences thereof, and to reduce noise average to improve noise evaluation.

Description

Suspension Control

1 is a schematic configuration diagram showing a basic configuration of a suspension control device of the present invention;

2 is a schematic configuration diagram showing an example of the suspension control device of the present invention;

FIG. 3 is a front view showing, in cross section, a portion showing an example of the damping force variable shock absorber employed in the suspension control device of FIG.

4 is an enlarged cross-sectional view showing a damping force adjusting mechanism in the state of maximum damping force when the vehicle body is raised,

5 is an enlarged cross-sectional view showing the damping force adjusting mechanism in the state of intermediate damping force when the vehicle body is raised, (a) is a view showing an operation flow path on the expansion side, (b) is a compression side,

6 is an enlarged cross-sectional view showing a damping force adjusting mechanism when the vehicle body is unchanged, (a) is a drawing showing the working oil path on the extension side, (b) on the compression side,

7 is an enlarged cross-sectional view showing a damping force adjusting mechanism in the state of maximum attenuation force when the vehicle body descends, (a) shows the working oil path on the extension side, (b) on the compression side,

8 is an explanatory diagram showing damping force characteristics with respect to the position of the valve body of the damping force variable shock absorber;

9 is a block diagram showing an example of a controller;

10 is an explanatory diagram showing gain characteristics of vibration input and output achieved in the damping force variable shock absorber.

11 is an explanatory diagram of a control map for setting the position of the valve body of the damping force variable shock absorber to a vertical velocity on a spring;

12 is an explanatory diagram of the damping effect by the vertical velocity-damping force characteristic on the basic spring;

13 is an explanatory diagram of the operating noise of the step motor,

14 is a timing chart illustrating operation noise when following a high response to a target rotational position of a step motor,

15 is a chart showing an arithmetic processing of damping force control to be executed in a controller as one embodiment of the suspension control device of the present invention;

FIG. 16 is a timing chart for explaining the operation noise when the followability to the target rotational position of the step motor is reduced by the calculation processing of FIG.

* Explanation of symbols for main parts of the drawings

1FL to 1RR: Wheel 2: Body

3FL to 3RR: Damping force variable shock absorber 4: Controller

5: outer dong 6: inner barrel

7: cylinder tube 8: piston

9: seal member 9U, 9L: upper and lower pressure chamber

10 center hole 11 lower half body

12: upper half body 13: extension side fluid passage

14: fluid passage on the compression side 14a, 14b: hole

15U, 15L: round annular groove 16, 17: long groove

18: expansion side disk valve 19: compression side disk valve

21: small diameter shaft portion 22: large diameter shaft portion

23: through hole 23a, 23b, 23c: hole

24a, 24b, 25a, 25b: through hole 26: arc-shaped groove

27: compression side fluid passage 28: compression side disk valve

29 nut 31 valve body

32: through hole 33: communication groove

34: long hole 35: piston rod

36 bodywork side member 37 bracket

38U, 38L: Rubber Bush 39: Nut

40: Bracket 41FL to 41RR: Step motor

41a: rotating shaft 42: connecting rod

43: bumper rubber 51FL to 51RR: vertical acceleration sensor

52: vehicle speed sensor 56: microcomputer

56a: input interface circuit 56b: output interface circuit

56c: processing unit 56d: storage unit

57FL to 57RR: A / D converter 58: A / D converter

59FL to 59RR: Motor drive circuit C1 to C4: Compression side flow path

T1 to T3: Extension side flow path

The present invention relates to a suspension control device for controlling the damping force of the damping force variable shock absorber to improve the riding comfort of the vehicle.

As a conventional semi-active suspension control apparatus, there exist some which were described in Unexamined-Japanese-Patent No. 3-42319, for example.

In this conventional example, the expansion-side damping force in the direction of stretching (hereinafter simply referred to as the stretching side) and the compression-side damping force in the direction of compression (hereinafter simply referred to as the compression side) are respectively at least low by the input of the control signal. A shock absorber that can be changed to a damping force and a high damping force, a spring speed measuring means for measuring the spring speed corresponding to the vehicle body side, and a relative speed measuring means for measuring the relative speed between the spring upper part and the spring lower part corresponding to the vehicle side. And the code judging means for judging the inconsistency and inconsistency between the speed code on the spring and the code of the relative speed, and when the two codes are identical and the code of the relative speed is positive (plus), the decompression side has a high damping force and a compression side. Is a low damping force, and when the sign of both codes is negative and the sign of the relative speed is negative (minus), Outputs a control signal, on the other hand, when the amount of code is inconsistent, and has a configuration with the control signal output means for outputting a control signal to all the height, side compression side to a low damping force.

In this conventional example, however, the high damping force and the low damping force set on the extension side and the compression side as the damping force variable shock absorbers can be set only to a constant value.

In other words, each damping force variable shock absorber used in this suspension control device has a specific high damping force set on the extension side and the compression side, and when the extension side is set to this constant high damping force, the compression side sets a constant low damping force. If the compression side is set to a constant high damping force, the stretching side is set to a constant low damping force, but the stretching side and the compression side can be set to a constant low damping force at the same time. That is, with this damping force variable shock absorber, each damping force on the extension side and the compression side can be set only at the so-called three positions.

On the other hand, the so-called sky hook theory has been conceived in terms of vibration reduction effect and attitude control of the vehicle body. In order to achieve the theory of the skyhook in a vehicle according to the so-called Karnopp's law or the like, the swing input such as the amount of motion generated in the vehicle body, specifically, the vertical velocity of the vehicle body spring, etc. In addition, the damping force of each shock absorber should be able to be changed continuously. Therefore, the present applicant first proposes a suspension control device using a damping force variable shock absorber described in, for example, Japanese Patent Application Laid-Open No. 5-328426 and the like.

The damping force variable shock absorber used in these suspension control devices will be described briefly. The expansion that is automatically opened and closed by a disc valve or a lead valve between a piston built in each shock absorber and a valve body built in the piston. When the side fluid passage and the compression side fluid passage are formed and the valve body is rotated or moved relative to the piston by an actuator, the piston-valve of each fluid passage interposed as an orifice in the extension side fluid passage and the compression side fluid passage Since the opening area between the sieves is changed, by varying and controlling the control amount for this actuator, the flow resistance of the variable orifice is changed, and the damping forces on the extension side and the compression side can be continuously changed and controlled individually.

When the damping force on the extension side is a relatively high damping force, the damping force on the compression side is a low damping force. When the damping force on the compression side is a relatively high damping force, the damping force on the stretching side is a low damping force. It is the same as or roughly the same as the example, and the damping force on the extension side or the compression side set on the high damping force side is set to increase or decrease continuously. As the actuator, specifically, a step motor is used, and the rotation angle of the step motor, that is, the number of steps (more precisely, the number of pulses of the control signal) is used as the control amount. In other words, at least the damping force on the high damping side has the same meaning as the relative rotation angle of the valve body, that is, the rotation position, in a linear relationship with the rotation angle of the step motor.

In this manner, the attenuation characteristics as shown in Fig. 8 can be obtained. However, the switching of the attenuation characteristics is determined by, for example, setting the step motor at one position every four steps (about 0.5 ° per step), and extending the control range. 20 positions are set in (HS) and 15 positions are set in the control range (SH) on the compression side. The arithmetic unit calculates the damping force required for each predetermined sampling time [Delta] T according to the detected up and down speed on the spring, and outputs a drive signal to the step motor so that the damping force can be selected.

In such a suspension control device, it is preferable to increase the control responsiveness of the damping force with respect to the vertical velocity of the spring detected as the road surface input or the vehicle body shaking input, in order to increase the suppression performance of the vehicle shaking as much as possible. In order to shorten the sampling time of the above described step motor and to improve the followability of the actual rotation position with respect to the target rotation position of each position set at each sampling time, the target rotation position and the actual The control signal is outputted to the step motor based on the deviation from the rotational position, and the step motor itself is also used with high responsiveness to improve the control performance.

By the way, in the conventional suspension control apparatus, the damping force is changed in accordance with the swing on the spring, and since the swing period on the spring is 1 ms (~ 2 ms), the step motor is switched to 70 positions per second, 1 The switching instruction per position is output every about 14 milliseconds (= 1 second / 70 positions). However, for example, if the step motor is responsive at 1 rotation per second, it is driven by one position (= 4 steps, 2 °), which is about several milliseconds. Therefore, for continuous position commands, the step motor is 14 milliseconds. There was a problem that the stationary state and the driving state were repeated every time, which caused vibration or noise. The operation of the step motor is similar to other actuators, and vibrations and noises are generated, and the tendency is as described later, when the step motor is rotated and shifted to a stationary state. It becomes remarkable in the opposite transition. In particular, at low speeds, the load noise is small, and there is a concern that noise due to vibration and noise at the time of driving and stopping the step motor may be noticed as abnormal sound. In this connection, by increasing the sampling time or the response time of the step motor, it is also possible to lengthen or erase the repetition interval between the stationary state and the driving state, but as described above, the responsiveness itself is deteriorated and the control performance is improved. There is a problem that cannot be expected.

The present invention was developed in view of the above-mentioned problems, and an object of the present invention is to provide a suspension control device capable of suppressing the noise effect of a step motor transmitted to a vehicle interior.

Thus, the suspension control device according to claim 1 of the present invention, as shown in the basic configuration diagram of FIG. 1, is mounted between the vehicle body side member and the wheel side member to rotate the step motor driven according to the input control signal. By controlling the position of the valve body by means of the valve body, the damping force variable shock absorber capable of setting either the damping force of the expansion side or the compression side to be large or the damping force of both of them can be set to a small value, and the vehicle body behavior related to the vertical velocity of the vehicle body on the spring. A damping force that suppresses the change in attitude of the vehicle body on the basis of the up / down speed detecting means on the spring and the up / down speed detection value on the spring detected by the up / down speed detecting means on the spring, and the target of the valve body corresponding to the damping force. Outputting the control signal to the step motor so that the valve position matches the actual position of the valve body. A suspension control apparatus provided with a fishing means, comprising: vehicle speed detecting means for detecting the front-rear speed of the vehicle, wherein the control means includes a vehicle speed detecting value detected by the vehicle speed detecting means being equal to or less than a predetermined vehicle speed value. And a holding time adjusting means for adjusting the holding time for which the step motor does not rotate for a long time.

In the suspension control apparatus according to claim 2 of the present invention, as shown in the basic configuration diagram of FIG. 1, the step motor is rotationally controlled in a certain order and in the opposite direction in accordance with the control signal. The means, when the vehicle speed detection value detected by the vehicle speed detecting means is equal to or less than a predetermined vehicle speed value, the rotation direction of the step motor is changed so as to match the actual position of the valve body to the target position of the valve body. And non-rotation time adjusting means for adjusting the non-rotation time for which the step motor does not rotate for a long time.

In the suspension control apparatus according to claim 1 of the present invention, as shown in the basic configuration diagram of FIG. 1, when the vehicle speed detection value detected by the vehicle speed detection means is equal to or less than a predetermined vehicle speed value, the holding means provided in the control means. Since the time adjusting means is configured to adjust the holding time when the target rotational position and the actual rotational position of the step motor coincide with each other, the load noise at the vehicle speed, which is generally conceivable, is the step. If it is set to a vehicle speed that is larger than the noise generated during operation of the motor, the vehicle is driven at a transition from the rotational drive of the step motor to the stop or from the stop state to the rotational drive, as described above, while the vehicle speed is below the predetermined vehicle speed value. The noise generation time and the frequency of occurrence of the high vibration level are reduced, resulting in a reduction in the overall noise. A noise evaluation is improved land becomes smaller. Of course, even in this low-speed driving state, even if the actual rotation position followability of the step motor to the target rotation position, that is, the damping force followability to the target damping force, is deteriorated, the road surface input as a control object for maintaining the vehicle body posture. By eliminating the housing and pitching movements, which are indicated by the housing motion and the body oscillation input, for example, even if the unevenness of the same road surface is reduced, the vertical acceleration generated in the vehicle body in the low-speed driving state becomes smaller, Since the required travel time is also long, the amount of bouncing momentum is considered to be small, and at the same time, it is considered that the vertical velocity of the spring, which is an integral value of the vertical acceleration of the vehicle body, is also reduced, so that the target value change amount of the damping force is also smaller. Therefore, the follower to the target damping force need not be so large. All. In addition, the amount of the rolling motion generated at the time of turning is proportional to the magnitude of the horizontal acceleration in the dimension that the lateral acceleration generated in the vehicle does not exceed the cornering force of the tire, and the lateral acceleration is proportional to the square of the vehicle speed.

Therefore, in such a low-speed driving state, it is considered that the rolling momentum, which is the body oscillation input, is small, and the target value change amount of the damping force and the change rate of the damping force will also be small, so that the followability to the target damping force need not be so high. At the same time, even if the small rolling amount is not suppressed with a high response, the steering stability of the vehicle does not significantly decrease. For this reason, the adjustment stability and the riding comfort are not deteriorated at least with respect to the bouncing movement and the rolling motion, and the steering stability and the riding comfort are not significantly reduced even for pitching movements such as tail cuts and nose dive.

In the suspension control apparatus according to claim 2 of the present invention, as shown in the basic configuration diagram of FIG. 1, the control means provided in the control means when the vehicle speed detection value detected by the vehicle speed detection means is equal to or less than a predetermined vehicle speed value previously set. Since the non-rotation time adjusting means is configured to adjust the non-rotation time when the rotation direction of the step motor is changed to be long, the load noise at the vehicle speed, which is generally conceivable, can be regarded as the step motor. When the vehicle speed is set to be larger than the noise generated during the operation of the motor, the target rotational position of the step motor and the actual rotational position do not coincide with each other, and the improvement effect of the noise evaluation by the holding time adjusting means is not exerted. The noise of the high vibration level which occurs during the rotational drive of the step motor while the vehicle speed is below the predetermined vehicle speed value, As described above, noise generation time and frequency of occurrence of high vibration level generated during the transition from the stop or stop state to the rotation drive by the step motor are reduced, and as a result, the overall noise energy is reduced, resulting in improved noise evaluation. do.

EXAMPLE

EMBODIMENT OF THE INVENTION Hereinafter, one Embodiment of the suspension control apparatus of this invention is described based on drawing.

FIG. 2 is a schematic configuration diagram showing an embodiment of the present invention, in which damping force variable shock absorbers 3FL to 3RR constituting a suspension device are provided between the wheels 1FL to 1RR and the vehicle body 2, respectively. The step motors 41FL to 41RR for converting the damping forces of the damping force variable shock absorbers 3FL to 3RR are controlled by a control signal by the controller 4 described later.

Each of these damping force variable shock absorbers 3FL to 3RR has a twin tube type gas-filled strut having a cylinder tube 7 composed of an outer cylinder 5 and an inner cylinder 6, as shown in FIGS. 3 to 7. The inner cylinder 6 is partitioned into upper and lower pressure chambers 9U and 9L by a piston 8 in sliding contact therewith.

As the piston 8 is particularly evident in FIGS. 4 to 7, the seal member 9 which is in sliding contact with the inner cylinder 6 is molded on the outer circumferential surface, and the center hole is formed on the inner circumferential surface. It is comprised as the cylindrical lower half body 11 which has 10, and the upper half body 12 inserted in the inside of this lower half body 11. As shown in FIG.

The lower half body 11 has a diameter larger than that of the expansion-side fluid passage 13 which penetrates up and down, and the extension-side fluid passage 13 which extends from the upper surface side to the lower side of the sealing member 9 downward. Compression-side fluid passage 14 composed of the large hole portion 14a and the hole portion 14b connected to the bottom portion of the hole portion 14a from the outer circumferential surface of the cylindrical body 11 and the center hole 10. Round grooves (15U, 15L) formed at the upper and lower end of the upper and lower openings, long grooves (16) communicating with the round annular grooves (15U) formed on the upper surface and the elongated side fluid passage (13), respectively, An elongated groove 17 is formed on the side and communicates with the round ring-shaped groove 15L, and the lower end side and the elongated groove 17 of the expansion-side fluid passage 13 are closed by the expansion-side disk valve 18. The upper end of the compression side fluid passage 14 is closed by the compression side disc valve 19.

The upper half body 12 has a smaller diameter shaft portion 21 fitted into the center hole 10 of the lower half body 11 and a diameter smaller than the inner diameter of the inner cylinder 6 integrally formed at the upper end of the shaft portion 21. A large diameter shaft portion 22, and at the center positions of the small diameter shaft portion 21 and the large diameter shaft portion 22, the middle portion of the large diameter shaft portion 22 from the bottom surface side of the small diameter shaft portion 21. Larger diameter than the hole 23a which reaches to the upper end side of this hole part 23a, the hole part 23b of smaller diameter, and the hole part 23b which connects to the upper end side of this hole part 23b. A pair of through holes 23 formed of the hole portions 23c is formed, and a pair penetrates radially into the inner circumferential surface at positions opposed to the rounded grooves 15U and 15L of the small diameter shaft portion 21, respectively. Through-holes 24a, 24b and 25a, 25b are drilled through and connected to the upper end of the hole 23a of the large diameter shaft portion 22 in succession. The arc-shaped groove 26 is formed, and the L-shaped compression side fluid passage 27 is formed in communication with the arc-shaped groove 26 and the bottom surface thereof. The lower end opening is closed by the compression side disk valve 28.

And the lower half 11 of the small diameter shaft part 21 in the state in which the lower half body 11 and the upper half body 12 inserted the small diameter shaft part 21 in the center hole 10 of the lower half body 11 was carried out. The nut 29 is screwed into the lower end portion which protrudes downward from the bottom, and is integrally connected.

Moreover, the cylindrical valve body 31 in which the upper end part which comprises a variable diaphragm | block which is comprised in the hole part 23a of the upper half body 12 is occupied rotationally is provided freely.

The valve body 31 reaches the inner circumferential surface in the radial direction at a position opposed to the arc-shaped groove 26 of the large diameter shaft portion 22 in the upper half body 12, as shown in FIG. At the same time as the through hole 32 is formed, the outer peripheral surface corresponding to the through hole 24a and 24b of the small diameter shaft portion 21 of the upper half body 12, as shown in FIGS. Communication grooves 33 are formed to allow them to communicate with each other, and as shown in FIG. 6, they are formed on the outer circumferential surface corresponding between the through holes 25a and 25b of the small diameter shaft portion 21 of the upper half body 12, respectively. An elongated hole 34 extending in the axial direction is formed to be connected to the inner circumferential surface.

Then, the positional relationship between the through hole 32, the communication groove 33 and the long hole 34 is the rotation angle of the valve body 31 shown in FIG. 8, that is, the step motors 41FL to 41RR described later. The damping force characteristic with respect to the step angle of is selected to be obtained.

That is, in the position A of FIG. 8 which is the clockwise maximum rotation angle position, for example, only the through hole 32 communicates with the arc-shaped groove 26 as shown in FIG. 4, so that the piston 8 As for the descending compression side movement, it passes from the lower pressure chamber 9L through the compression side fluid passage 14, and passes through the orifice formed by the opening end and the compression side disk valve 19 to the upper pressure chamber 9U. The through-hole 32, the arc-shaped groove 26, and the compression-side fluid passage (2) through the compression-side flow path C1 and the lower pressure chamber 9L shown by the broken dashed line and the inner circumferential surface of the valve body 31. 27, a compression side flow path C2, shown by a broken line toward the upper pressure chamber 9U, is formed through the opening end and the orifice formed by the compression side disk valve 28, and also the piston 8 The upward movement on the extension side passes from the upper pressure chamber 9U through the elongated groove 16 and the extension side fluid passage 13 to the opening. Only the expansion-side flow path T1 shown by the broken line which passes through the orifice formed by the stage and the expansion-side disk valve 18 toward the lower pressure chamber 9L is formed, and the expansion-side high flow rate rapidly increases with the increase of the piston speed. The damping force is generated, and on the compression side, a low damping force is generated which increases slightly with the increase of the piston speed.

By rotating the valve element 31 counterclockwise from this A position, the through-holes 24a and 25a of the communication groove 33 of the valve element 31 and the small diameter shaft portion 21 as shown in FIG. This connection is brought to pass, and the opening area between the communication groove 33 and the through holes 24a and 25a gradually increases as the rotation angle increases. For this reason, about the extension side movement of the piston 8, as shown to Fig.5 (a), the long groove 16 in parallel with the flow path T1, the round ring groove 15U, and the through hole 24a are shown. , The lower pressure passing through the communication groove 33, the through-hole 24b, the round ring groove 15L, the long groove 17 through the orifice formed by the long groove 17 and the compression-side disk valve 18 A flow path T2 directed to the seal 9L is formed, and the maximum area of the damping force is increased in the opening area between the communication groove 33 and the through holes 24a and 25a of the small diameter shaft portion 21 as shown in FIG. It gradually decreases with respect to the extension side movement, and maintains the minimum damping force state in order to maintain the state in which the flow paths C1 and C2 are formed as shown in (b) of FIG.

In addition, when the valve body 31 is rotated counterclockwise to the vicinity of B, as shown in FIG. 6, the valve body 31 is successively passed through the long holes 34 between the through holes 25a and 25b of the valve body 31. As shown in FIG. It is in a state. For this reason, the extension side movement of the piston 8, as shown in Fig. 6 (a), has a long groove 16, a rounded groove 15U, and a through hole 25a in parallel with the flow paths T1 and T2. A flow path T3 is formed through the long hole 34 and the hole 23a and directed to the lower pressure chamber 9L, and the expansion-side damping force is brought to a minimum damping force, and the piston 8 moves on the compression side. In addition to the passages C1 and C2, the passage C3 that passes through the hole 23a, the elongated hole 34, the through hole 25a, the rounded ring groove 15U, and reaches the elongated groove 16. And a hole 23a, a long hole 34, a through hole 25b, a rounded ring groove 15L, a through hole 24b, a communication groove 33, a through hole 24a, a rounded ring groove ( A flow path C4 is formed which passes through 15U and reaches the long groove 16, and maintains the minimum damping force state as shown in FIG.

In addition, when the valve body 31 is rotated counterclockwise, the opening area between the long hole 34 and the through holes 24b and 25b is reduced, and the long hole 34 and the long hole 34 at the rotation angle θ _B2 . The space between the through holes 24b and 25b is blocked as shown in FIG. 7, but the opening area between the through holes 32 and the arc-shaped grooves 26 is gradually smaller from the rotation angle θ _B2 . Lose.

For this reason, the flow paths T1 and T2 coexist with respect to the extension-side movement of the piston 8 from the rotation angle θ _B2 to the maximum rotation angle θ _{C in the} counterclockwise direction, so that the minimum reduction force is applied. On the contrary, with respect to the compression-side movement of the piston 8, the opening area gradually decreases between the through hole 32 and the arc-shaped groove 26, so that the maximum damping force gradually increases, and the valve body 31 is positioned. When C is reached, the through-hole 32 and the arc-shaped groove 26 are cut off as shown in FIG. 7, so that the upper pressure chamber (9L) from the lower pressure chamber 9L is used for the compression-side movement of the piston. The flow path reaching 9U becomes only the flow path C1, and the compression-side high damping force state becomes.

Therefore, if the rotation angle of this step motor is made into the position P, the position P in which the damping force on the extension side becomes the maximum damping force becomes the expansion-side maximum position P _TMAX , and the position P in which the damping force of the compression side becomes the maximum damping force is the compression side. The maximum position P _CMAX , where for convenience, the position P corresponding to the _{middle value} of the _range in which the extension axis damping force and the compression side damping force are set to low damping force is set to 0, and the position change in the direction in which the extension side damping force increases is positive. In addition, if the position change in the direction in which the compression-side damping force increases is negative, the extension maximum position P _TMAX is simply expressed as P _MAX as a positive sign, and the compression maximum position P _CMAX is simply expressed as a negative sign (-P _MAX). Is indicated by). However, the absolute value of each of these maximum positions | P _MAX | does not necessarily have to be the same control value. The negative threshold value P _C1 from the positive threshold value P _{T1 in} which the position P is zero among the total damping force control ranges from the maximum compression position (-P _MAX ) to the negative value to the extension maximum position P _MAX to be the positive value is negative. The range of up to the low damping force D / F _{T0 on the} compression side is the low damping force D / F _C0 on the compression side, and the soft range (hereinafter, simply referred to as SS range for achieving comfort in low-speed driving state) in the operation processing described later. The expansion-side control range in which the position P is larger in the forward direction, that is, the position P from the positive threshold P _T1 to the extension-side maximum position P _MAX, which is a positive value, is set to have a high extension-side damping force (hereinafter simply referred to as HS). Range P is smaller than the negative direction, that is, position P is the compression-side maximum position of the negative value from the negative threshold P _C1 (-P). _MAX ) is the compression-side control range (hereinafter referred to simply as the SH range) in which the compression-side damping force is set high. Thus, the positive threshold value P _T1 is referred to as the positive decay threshold value, and the negative threshold P _C1 is referred to as the decay threshold value.

On the other hand, a cylindrical piston rod 35 is fitted into the hole 23c of the upper half body 12, and an upper end of the piston rod 35 protrudes upward from the cylinder tube 7 as shown in FIG. In addition, the upper end side is fixed to the bracket 37 mounted on the vehicle body side member 36 with the rubber bushes 38U and 38L by the nut 39, and at the same time, the bracket on the upper end of the piston rod 35. Step motors 41FL to 41RR are fixed in such a state that the step shafts 41FL to 41RR protrude downward from the rotary shaft 41a, and the rotary shaft 41a and the valve body 31 described above are inserted into the piston rod 35. It is connected by the loosely fitted connecting rod 42. Reference numeral 43 is a bumper rubber. The lower end of the cylinder tube 7 is connected to a wheel side member (not shown).

The engine roller 4 has a vertical acceleration detection value X of analog voltages, which are positive in the upward direction and negative in the downward direction according to the vertical acceleration provided on the vehicle body side corresponding to each wheel position on the pressure side as shown in FIG. Vertical acceleration sensors 51FL to 51RR as vertical acceleration detection means for outputting _{2FL to} X _2RR , and vehicle speed sensor 52 for outputting a vehicle speed detection value V formed as a positive analog voltage corresponding to the vehicle speed are connected, and each damping force is output to the output side. Step motors 41FL to 41RR for controlling the damping force of the variable shock absorbers 3FL to 3RR are connected.

The controller 4 includes a microcomputer 56 having at least an input interface circuit 56a, an output interface circuit 56b, an arithmetic processing unit 56c, and a storage unit 56d, and up / down acceleration sensors 51FL to 51RR. A / D converters _57FL to _57RR for converting the vertical acceleration detection values X _2FL to X _2RR into the digital values and supplying them to the input interface circuit 56a, and the vehicle speed detection values V of the vehicle speed sensor 52 as digital values. The step control signals for the step motors 41FL to 41RR outputted from the A / D converter 58 and the output interface circuit 56b which are converted to the input interface circuit 56a and supplied to the input interface circuit 56a are input. The motor driving circuits 59FL to 59RR are converted to pulses to drive the step motors 41FL to 41RR.

Here, the data processing unit (56c) of the microcomputer 56 value by the calculation processing described later each of the vertical acceleration detected by integrating the X _2FL ~X _2RR and calculates the vehicle body vertical velocity X _2FL ~X _2RR, each Calculate and set the target rotation angle of the step _motor according to the body up / down speed X _{2FL to} X 2RR, that is, the target position P _D of the valve body, and calculate the difference value between the target position P _D and the current position P _A. The step control amount is output to the motor drive circuits 59FL to 59RR, and the rotation angle of the step motor, that is, the damping force of each damping force variable shock absorber 3FL to 3RR according to the position of the valve body is open looped. When the vehicle speed detection value V is equal to or less than a predetermined predetermined vehicle speed value V ₀ , for example, when the current position P _A coincides with a target position P _D , the holding time for keeping the step motor in the holding state is extended to a predetermined time T1. Executes a hold control, and, for example, in the target position step Motor which the forward direction to achieve a P _D (here and in the direction to rotate the step Motor in a clockwise direction, as has been described above it As such, when switching from the reverse direction to the reverse direction from the reverse direction to the reverse direction (herein, the step motor is rotated counterclockwise, and simply referred to as reverse direction as described above). When the target position P _D shifts from the increasing direction to the decreasing direction or from the decreasing direction to the increasing direction, a set control is performed to lengthen the non-rotation time for making the step motor non-rotating to a predetermined time T ₂ . .

In addition, the storage device 56d stores a program necessary for the arithmetic processing of the arithmetic processing unit 56c in advance, and sequentially stores necessary values and arithmetic results in the arithmetic processing.

Next, the basic principle of damping force control of the Sangik angular damping force variable shock absorber to be executed in the present embodiment will be described.

First, when the damping force variable shock absorber having the damping force characteristic as shown in FIG. 8 is used, the gain characteristic of the output actually oscillating with respect to the rocking input which is intended to act on the vehicle body is shown as in FIG. Among these, relatively gentle body fluctuations, that is, body fluctuations in the low frequency band, give vehicle occupants a sense of instability, and therefore it is necessary to actively attenuate them. By the way, the vibration input of the lower part of the spring which is relatively fast causes the damping force to become rugged and impairs the ride comfort of the occupant. Thus, the resonant frequency of the body oscillation input / output system or control system equipped with the damping force variable shock absorber is set to the low frequency band of the frequency of the oscillation input, and the gain of the resonant frequency is equal to the solid line from the state shown in FIG. By reducing the state, the damping force is increased so that the gain of the oscillation input frequency to be actively attenuated becomes smaller in the negative direction. Therefore, when the damping force control which achieves this gain characteristic is performed, smoothness can be given to the vibration input of high frequency, and the vibration removal effect by the high damping force can be achieved against the big fluctuation | variation of a vehicle body.

In the body oscillation input / output system or the control system set as described above, in order to achieve the Karnoff law, as shown by the dashed-dotted line in FIG. 11, the up / down speed X _2i (i = FL to RR) on the spring as the swing input is shown The target position may be set linearly, for example, as the proportional coefficient α. However, in the case where the vehicle is good and traveling on a flat road surface, i.e., for a rocking input having a small damping force, even if it does not substantially change the damping force within the soft range (SS range), the step Rotating the motor, that is, changing the position of the valve body will be a waste of energy, and there is also a problem of noise generated substantially in accordance with the rotation of the step motor. Therefore, the deadband is set from the positive deadband value X _2i0 to the negative deadband value (-X _2i0 ) with respect to the up and down speed X _2i on the spring which is the oscillation input, and the target position when the up and down speed X _2i on the spring is in this dead zone. When P _D is 0 and the vertical velocity X _2i on the spring is not in this range, the target position P _D increases linearly with the proportional coefficient α as the vertical velocity X _2i on the spring increases.

Here, if the vertical velocity-target position correlation characteristic on the spring of FIG. 11 is assumed to be a control map, when the target position P _D becomes the extension-side maximum position P _MAX , the upper and lower springs corresponding to this target position P _D are If the speed X _2i and down speed X _{2i mAX} on the kidney-side up to the spring, the upper and lower on the spring rate X _2i a target position in the up-and-down velocity X _{2i mAX} or more regions on the kidney-side up spring P _D is height-side up position to the P _mAX It is fixed. When the target position P _D is at the maximum compression side position (-P _MAX ), if the vertical velocity X _2i on the spring corresponding to this target position P _D is the vertical velocity on the compression side maximum spring (-X _{2i MAX} ), the spring The target position P _D is fixed at the compression side maximum position (-P _MAX ) in the region where the vertical velocity X _2i of the phase is less than or equal to the vertical velocity (-X _{2i MAX} ) on this compression side maximum spring. In addition, when the target position P _D becomes the positive deceleration threshold value P _T1 , the vertical phase X _2i on the spring is set to the vertical speed threshold X _2i01 of the positive deceleration spring value, and the spring phase when the negative deceleration threshold value P _C1 is obtained. Let vertical velocity X _{2i be} the vertical velocity threshold (-X _2i01 ) on a negative damper spring.

However, if the position P is linearly set with respect to the vertical velocity X _2i on the spring excluding the dead zone, the damping force characteristics shown in FIG. 8 are similar to those of FIG. 12 (c) with respect to the vertical velocity X _2i on the spring. Appears together. That is, if the accumulation of the position-damping force characteristic shown in FIG. 8 and the accumulation of the up-down speed-damping force characteristic on the spring shown in FIG. 12C are equal, the up-down speed-damping force on the spring shown in FIG. The soft range (SS range) of the characteristics is widened by the up / down speed dead zone on the spring maintained at position 0, and the extension side control range (HS range) or compression side control range (SH range) is located outside thereof. Think about it. With respect to the up-down speed-damping force characteristic on the spring, the action when the up-down speed X _2i on the spring as input in Fig. 12 (a) is input as the transient vibration input will be considered. First, the vertical velocity X _2i on the spring increasing in the positive region as an initial input continues to increase further above the vertical velocity threshold X _2i01 on the positive damping spring at time t ₁ . The increasing tendency of the damping force gradually decreased, and at some time, the increase tended to decrease beyond the maximal point and decreased in the positive area, and sooner or later _fell below the vertical velocity threshold X _2i01 on the positive damping spring at time t ₂ . On the other hand, the damping force on the extension side and the compression side in the SS range is, for example, 0, and the damping force D / F achieved by the damping force variable shock absorber is the position P, the vertical velocity X _2i on the spring excluding the dead band and In the linear relationship, the extension-side damping force D / F in synchronism with the increase and decrease of the vertical velocity X _2i on the spring at the time t ₁ to t ₂ from the start t ₁ to the time t _{2 is shown} in Fig. 12 (b). It happens together. In other words, the vertical velocity X _2i on the spring effectively attenuates with the damping force D / F according to its increase and decrease. At this time, when the wheel moves upward due to the unevenness of the road surface, the damping force on the compression side is minimized, so that the influence on the spring which is the vehicle body can be reduced. Moreover, even if the wheel moves downward due to the unevenness of the road surface at this time, the damping force on the extension side is small, so that the influence on the spring on the vehicle body can be reduced.

The vertical velocity X _2i on the spring which continues to decrease further begins to decrease in the negative region soon and continues to decrease further _below the vertical velocity threshold (-X _2i01 ) on the negative damper spring at time t ₃ , which immediately vibrates. The decreasing tendency gradually decreases due to the characteristics of the input and the increasing action of the compression-side damping force, which will be described later, and begins to increase in the negative region beyond the minimum point at some time, and sooner or later on the negative damping spring of the negative at time t ₄ . It was above the speed threshold (-X _2i01 ). To time t ₃ ~t ₄ at time t ₄ to the time from t _3, so increasing or decreasing the speed of the upper and lower X _2i on the spring in synchronism with the particular compression side damping force D / F is generated as in the 12 degree (b), the spring The vertical velocity X _2i of the phase is effectively attenuated by the D / F according to its increase and decrease. The absolute value | X _2i | of the vertical velocity of the spring on the minimum is smaller than the absolute value | X _2i | of the vertical velocity of the spring on the maximum.

Then, at time t _{5 to} t ₁₁ , the swing on the spring is attenuated by the above repetition.

In this way, when the vertical velocity X _2i on the spring with a small absolute value including the dead zone occurs, the position P only changes small, and when it is in the range from the positive damping threshold P _T1 to the negative damping threshold P _C1 . In addition, the damping force is kept low on the extension side and on the compression side. This fact has the effect of achieving a comfortable ride feeling corresponding to the heavy feeling and the like felt in a large-volume vehicle as described above, and the damping force of the damping force variable shock absorber achieved is set to be as low as possible on the extension side and the compression side.

Next, the noise problem at the time of operating the step mou as described above will be considered.

First, as a vibration level, the noise energy transmitted to the vehicle body shaft when the step-Mount is rotated with the predetermined drive torque and when the drive torque is applied and maintained to the extent that it is not rotated by external force is shown. Shown in As is apparent from the figure, the vibration level in the driving state of this step motor is large, and the vibration level in the holding state is small. In addition, although it is difficult to recognize the same figure, it has been found that a large vibration level appears even when the transition from the holding state to the driving state or the transition from the driving state to the holding state, that is, when the rotation angle acceleration of the step motor rapidly changes. . Although the cause is not known yet, as described above, it is thought that the change in the force of the rotor of the step motor stops or rotates is transmitted to the housing of the step motor as a vibration input, and then to the vehicle body side again. .

By the way, in the suspension control apparatus as described above, in order to suppress the fluctuation of the vehicle body as much as possible, it is necessary to increase the control response of the damping force with respect to the vertical velocity of the spring detected as the road surface input or the vehicle body fluctuation input. In the suspension control apparatus, specifically, the sampling time of the chopping control of the step motor is set to a short time, and the followability of the actual rotation position with respect to the target rotational position of the step motor set to each sampling time is specified. For each sampling time, a control signal based on the deviation between the target rotational position and the actual rotational position is output to the step motor, and the step motor is set in the relatively short time to achieve the followability. A high responsiveness has been adopted that can reliably rotate to the target rotational position within the sampling time and stop reliably at that position.

The control mode of the damping force follow-up improvement and the noise energy characteristics are considered in accordance with the basic principle of the damping force control.

Here, the arithmetic processing of the damping force control is executed for each sampling time DELTA T set to a predetermined relatively short time by a timer interrupt or the like, and as a result, the target position P _D is shown at time t ₁ as shown in Fig. 14A. From time t ₁₈ to a constant inclination in the stretched-side area, that is, the positive area, increases at a constant slope, and then decreases to a constant inclination in the stretched-side area, that is, in the positive area, from time t ₁₈ to time t ₃₀ (actual target position P). _D is calculated and set step by step for each sampling time ΔT). On the other hand in the time t ₁ the target position P _D to the current position P _A it is because there is match, the sampling time △ T time t ₂ after the post, the sampling time △ T for each time _{t 4, t 6, t 8} , ... The rotation angle following control of the step motor is executed so that the deviation between the target position P _D and the current position P _A becomes 0 at, t ₂₈ , t _{30. During} each sampling time ΔT, the target position P _D achieved just before It is assumed that is maintained as the current position P _A. In this example, the sampling times t ₂ , t ₄ ,... Are set within the maximum rotational drive speed of the step motor set in advance. At position t ₃₀ , position P _A is currently following target position P _D.

Therefore, in this case, the clockwise rotation with increasing position is defined as the rotation in the forward direction, and the counterclockwise rotation with the decreasing position is defined as the rotation in the negative direction. Thus, for example, the driving force T of the step motor required for the forward rotation is defined. Value and absolute value of the driving force of the step motor at each sampling time ΔT even if the driving force T of the step motor required for rotation in the negative direction is shown as a negative value or each sampling time ΔT is shown as a negative value. T | is shown as (b) of FIG. That is, for example, the step motor becomes the rotation driving state from the maximum second sampling time t ₂ to the time t ₃ after a predetermined time, and then the time from the time t ₃ to the time t ₄ is in a holding state. The absolute value | T | of the driving force of the step motor during time [Delta] T becomes a rectangular wave shape. Here, the actual step motor rotation drive / maintenance control is chopping control as described above. However, the present position P _A of the step motor is not shown in FIG. Follow as shown by the broken line in (). However, in order to facilitate understanding, the sampling times t ₂ , t ₄ ,... , at position t ₃₀ , the current position P _A follows the target position P _D in real time.

Since the current position P _A follows the target position P _D in real time at each sampling start t ₂ , t ₄ ,..., T ₃₀ , the absolute value of the driving force of the step motor | T | Increase or decrease in shape. When the vibration level is polymerized to the driving force of the step motor, the vibration level is large in all rotational driving states except at least the step motor holding state. Furthermore, as described above, driving from holding or holding from driving is performed. Considering the fact that the vibration level is amplified at the transition time and there is no active damping effect, the noise energy of this series of control times t _{2 to} t ₃₀ becomes a considerably large value.

In addition, as described above, the need for the damping force variable shock absorber with the step motor to approach the vehicle interior has been recently increased. Thus, such a large amount of noise energy is transmitted to the vehicle interior. When the vibration level such as road noise transmitted to the vehicle interior is small, it may be perceived as an abnormal sound. In general, two methods can be considered to improve such noise evaluation, and reducing the vibration level itself in driving and maintaining the step motor is practically achieved even in the sense that the driving force and the holding force cannot be secured. Since it is difficult to do so, here, the holding state with a small vibration level is lengthened, and the rotation drive state with a relatively high vibration level is shortened or the frequency | count of occurrence thereof is reduced, and overall noise energy is reduced. Specifically, the vibration level of the road noise transmitted to the interior of the vehicle increases uniformly with the increase of the vehicle speed, and the vibration level of the step motor operating noise transmitted to the interior of the vehicle is similarly the interior of the vehicle. When the vehicle speed capable of masking as a vibration level such as road noise transmitted to the vehicle is set to the predetermined vehicle speed value V ₀ , and the vehicle speed detection value V detected by the vehicle speed sensor 52 is less than or equal to the predetermined vehicle speed value V ₀ , the holding state. Is increased to a predetermined time T ₁ . That is, when the above condition is satisfied, the hold control timer counter (hereinafter referred to simply as the holder timer counter) starts to increase CNT ₁ , and this timer counter CNT ₁ divides the predetermined time T ₁ by the sampling time ΔT. The number of steps (step amount) S, which is equivalent to the rotation angle formed by the deviation between the target position P _D , which is a control signal to the step motor, and the current position P _A , until the count value CNT ₁₀ is set to 0, is forcibly set to zero. The predetermined vehicle speed value V ₀ is set within a vehicle speed range corresponding to a relatively low speed travel state.

By the way, when hold control for extending the holding time of the step motor is performed in this way, the followability of the current position P _A to the target position P _D , that is, the followability of the actual damping force to the target damping force, is lowered. However, as described above, since the hold control is performed at a relatively low speed driving state, compared with the medium and high speed driving states, even when the road surface roughness is equal, the bouncing momentum and its speed are small, and the lateral speed is so small that the loading momentum and the Since the speed is also small, and therefore the change amount and the rate of change of the target damping force are small, the adjustment stability and the ride comfort are not deteriorated even if the track damping force is not particularly maintained. Also, pitching momentum such as nosedive or tail cut is small, so if the target damping force is attained by rapidly changing the deceleration force until the momentum becomes the maximum without maintaining the high follow-up of the target damping force, Stability is not compromised.

However, performing hold control in the low-speed running state, that is, lengthening the holding time of the step motor, is based on the premise that the current position P _A coincides with the target position P _{D even} in the meaning of the holding state. (In the arithmetic processing described later, it is difficult to recognize the coincidence of the two in the so-called open loop control, so that the current position P _A is the target position P _D when the rotational drive speed of the step motor is equal to or less than the maximum rotational drive speed. Hold control is started from the sampling time that is considered to be reached). For example, in the case where small road surface irregularities continuously increase or decrease in the target position P _D in a continuous manner, the current position P depends on the response time of the step motor. _{It is possible that A} does not coincide with the target position P _D for a long time. Since the hold control for prolonging the holding time as described above is not executed, there is a fear that the noise evaluation is lowered.

Thus, a set control for suppressing the stepping-off when the target position P _D of the step motor is increased or decreased, that is, when the step motor is rotated in the forward direction or in the reverse direction or in the reverse direction in the forward direction. That is, it is necessary to lengthen the non-rotation state control time of the step motor. Specifically, since this set control is a countermeasure in the case where it cannot be shifted to the hold control, it is when the vehicle speed detection value V detected by the vehicle speed sensor 52 is equal to or less than the predetermined vehicle speed value V ₀ , and the previous time of the target position. the value obtained by subtracting the previous value P _{D (n-1)} from the value P _{D (n-2)} and, subtracting the value P _{D (n)} of this time from the previous value P _{D (n-1)} value, multiplied by the value In the case of this denial, it is determined that the target position P _D changes from increasing direction to decreasing direction or decreasing direction to increasing direction so that the rotation direction of the step motor is changed, and thus the timer counter for setting control (hereinafter, simply set timer timer) is determined. CNT ₂ is increased, and the timer counter CNT ₂ is transferred to the step motor until the predetermined counter value CNT ₂₀ obtained by dividing the predetermined relatively long predetermined time T ₂ by the sampling time ΔT is reached. The step amount S as a control signal Forced to zero.

In this set control, it is possible that the current position P _A of the step motor may be kept inconsistent with the target position P _D calculated and set at any one sampling time, but the target position P set according to the continuous road surface irregularities. _Since the increase / decrease variation of _D will be small, even if the actual damping force is slightly sag with respect to the optimum damping force in such a low-speed driving state, not only the adjustment stability but also the ride comfort will not be greatly reduced.

In this embodiment, according to the original purpose of the hold control and the set control, for example, transition to the set control during the hold control, or the transition to the hold control during the set control, both the holding time and the non-rotation time Don't let it continue running.

Then, the arithmetic processing unit 56c of the microcomputer 56 next time achieves the vertical velocity-target position-damping force correlation characteristic on the spring and at the same time improves the noise evaluation in the low-speed driving state according to the basic principle. Fig. 15 shows the arithmetic processing of the damping force control to be carried out in Fig. 1). In the present embodiment, the target position P _D which is basically set is calculated according to a calculation formula rather than a map and color. During this arithmetic processing, the hold control flag F ₁ indicates that the hold control is in the set state of 1 and not in the reset state of zero. During this arithmetic process, the hold timer counter CNT ₁ indicates that the predetermined time T ₁ has elapsed at a predetermined counter value CNT ₁₀ . In addition, during this arithmetic processing, the set control flag F ₁ indicates that the set control is in the set state of 1, and not in the reset state of zero. During this arithmetic processing, the set timer counter CNT ₂ indicates that the predetermined time T ₂ has elapsed at a predetermined counter touch CNT ₂₀ .

That is, the process of FIG. 15 is executed as a timer interrupt process every predetermined time [Delta] T (e.g., 3.3 msec), and first, the vertical acceleration detection value X on each spring detected by the respective vertical acceleration sensors 51FL to 51RR in step S1. Read out _2i (i = FL to RR).

Next, the process proceeds to step S2, where a high pass filter is performed on the up / down acceleration detection value X _2i read out in step S1 by the digital high pass filter constructed by a program, for example, on each spring phase. The drift overlap component of the vertical velocity detection value X _2i is removed. The digital high pass filter cut-off frequency can be appropriately selected and set as a temporary variable of a program for constructing the filter as is known.

Next, the process proceeds to step S3, where, for example, a low pass filter is performed on the up / down acceleration detection value X _2i on each spring from which the drift overlap component is removed in the step S2 by means of a digital low pass filter constructed by a program. The up-down position detection value X _2i on each spring phase-matched as an integral value is computed. The cut-off frequency of the digital low pass filter can be set by appropriately selecting a temporary variable of a program for constructing the filter as is known. In addition, calculation of the vertical velocity detection value _X2i on each spring can also be calculated by the existing integral calculation process instead of the low pass filter process.

Subsequently, the process proceeds to step S4, where it is determined whether the up / down speed detection value X _2i on each spring calculated and set in step S3 is less than zero, that is, whether or not it is non-going, and when the up / down speed detection value X _2i on the spring is negative, The flow advances to step S5, otherwise the flow advances to step S6.

In the step S5, using the up and down speed on the compression-side maximum spring (-X _{2i MAX} ) and the up and down speed detection value X _2i on each spring calculated and set in the step S3 and the negative dead band (-X _2io ) In step S7, the compression-side target position proportionality coefficient α1 is calculated. When the absolute value of the negative deadband threshold (-X _2iO ) is equal to the absolute value of the positive deadband value (X _2i0 ), the double parenthesis in the formula may be solved.

_{α1 = (X 2i - (X} 2iO)) / (- X 2iMAX)

In step S7, it is determined whether or not the compression-side target position proportional coefficient α ₁ calculated in step S5 is larger than _{1. If} the compression-side target position proportional coefficient α ₁ is larger than ₁ , the process proceeds to step S8. If no, the process proceeds to step S9.

In step S8, the compression-side target position proportional coefficient alpha 1 is set to 1, and then the flow advances to step S9.

In the step S9, using the compression-side target position proportional coefficient α1 and the compression-side maximum position (-P _MAX ) set in the step S5 or step S8, this time, After calculating the value P _{D (n)} , the process proceeds to step S10.

P _{D (n) =} α ₁ (-P _MAX )

On the other hand, in step S6, using the up-and-down speed X _{2i MAX} on the extension-side maximum spring and the up-down speed detection value X _2i on each spring set and calculated in step S3, and the positive deadband threshold value X _2i0 , the expansion-side side according to the following expression After the target position proportional coefficient α ₂ is calculated, the process proceeds to step S11.

α ₂ = (X _2i + X _2i0 ) / X _{2i MAX}

In step 11, it is determined whether the expansion-side target position proportional coefficient α ₂ calculated in the step S6 is larger than 1, and if the expansion-side target position proportional coefficient α ₂ is larger than 1, the process proceeds to step S12. In the case, the process proceeds to step S13.

In step S12, the expansion-side target position proportional coefficient alpha ₂ is set to 1, and then the flow advances to step S13.

In the step S13, the current value P of the target position on the extension side, that is, the forward direction according to the following four expressions using the expansion-side target position proportional coefficient α ₂ and the expansion-side maximum position P _MAX set in the step S6 or step S12. _{D (n)} is calculated and the process proceeds to the step S10.

_{P D (n) = α 2} · P MAX

In step S10, the vehicle speed detection value V detected by the vehicle speed sensor 52 is read-in.

Next, when the processing proceeds to step S14, in step S10 reads the vehicle speed detected value V input, and said predetermined determining whether the vehicle speed value V ₀ of all jakeunga, the vehicle speed detecting value V is predetermined smaller than the vehicle speed value V _0, the The flow advances to step S15, otherwise, the flow advances to step S16.

In step S15, the hold control flag F ₁ is reset to 0, and the set control flag F ₂ is reset to 0, and then the process proceeds to step S17.

In step S17, the hold timer counter CNT ₁ is cleared and the set timer counter CNT ₂ is cleared, and then the procedure goes to step S18.

In step S18, the current position P _{A previously} updated and stored in the storage device 56d is subtracted from the current value P _{D (n)} of the target position calculated and calculated in step S9 or step S13. After calculating a rotation angle as a step amount, it transfers to step S19.

In step S19, it is determined whether or not the absolute value | S | of the step amount calculated and set in said step S18 is equal to or less than the maximum step amount S _MAX achieved by one predetermined calculation process, and the absolute value | S | of the step amount is determined. If S is less than or equal to the maximum step amount S _MAX , the process proceeds to step S20, and otherwise, the process proceeds to step S21.

In step S20, after setting the step amount S calculated and set in said step S18 as it is to the step amount S which is a control signal to a step motor, it transfers to step S22.

In step S21, it is determined whether or not the step amount S calculated and set in step S18 is greater than zero, that is, whether it is positive or not, and if the step amount S is positive, the process proceeds to step S23; otherwise, step S24 Go to

In step S23, after setting the step amount S, which is a control signal to the step motor, to the positive value S _MAX of the maximum step amount, the process proceeds to step S22.

In step S24, after setting the step amount S, which is a control signal to the step motor, to a negative value (-S _MAX ) of the maximum step amount, the process proceeds to step S22.

On the other hand, in the step S16, to the set ring control flag F ₂ is determined whether or not there in the reset state 0, in a case where the set ring control flag F ₂ is zero, the reset state of In, and the operation proceeds to step S25, If not, the flow proceeds to step S26.

In the step S25, in the case to which the hold control flag F ₁ determines whether or not the zero reset state is applied in the case that the hold control flag F ₁ is zero reset state of In, and the operation proceeds to step S27, otherwise, the step Go to S28.

In step S27, the target is similar to the value obtained by subtracting the previous value P _{F (N-1)} of the target position from the previous value P _{D (n-2)} of the target position updated and stored in the storage device 56d. Whether or not the value obtained by subtracting the current value P _{D (n)} of the target position calculated in step S9 or step S13 from the previous value P _{D (n-1)} of the position is 0 or more, that is, the multiplied value It is determined whether or not the result is negative. If the multiplied value is not negative, the process proceeds to step S29, and when otherwise, the process proceeds to the step S26.

In step S29, it is determined whether or not the current position P _A of the step motor matches the previous value P _{D (n-1)} of the target position, so that the current position P _A is the previous value P _D of the target position ₍ If it matches _n-1) , the process proceeds to the step S28, otherwise the process proceeds to the step S15.

In the step S28, the process proceeds to the set ring control flag F ₂ reset to zero and at the same time, after clearing the set timer ring counter CNT ₂ in step S30.

In step S30, after setting the hold control flag F ₁ to 1, the routine advances to step S31.

In step S31, after the hold timer counter CNT ₁ increases, the routine advances to step S32.

Wherein in the step S32, the hold timer counter CNT ₁ is the predetermined time by determining whether it is less than a predetermined count value CNT ₁₀ corresponding to T _1, the hold timer counter CNT ₁ is less than the value CNT ₁₀ a predetermined count, the step The flow advances to S33, and if not, the flow proceeds to step S15.

On the other hand, in step S26, the hold control flag F ₁ is reset to 0, and the hold timer counter CNT ₁ is cleared, and then the process proceeds to step S34.

In step S34, after setting the set control flag F ₂ to 1, the routine advances to step S35.

In step S35, after the setting timer counter CNT ₂ is increased, the routine advances to step S36.

In the step S36, the set ring timer counter CNT case ₂ when the predetermined time by determining whether it is less than a predetermined count value CNT ₂₀ equal to T _2, the set ring timer counter CNT ₂ is less than the value CNT ₂₀ predetermined count The flow proceeds to step S33, otherwise, the flow proceeds to step S15.

In step S33, after setting the step amount S, which is a control signal to the step motor, to 0, the process proceeds to step S22.

In step S22, after outputting the step amount S set in any one of said step S20, S23, S24, S33 as a control signal to a step motor toward each said motor drive circuit 59FL-RR, it returns to step S37. To fulfill.

In step S37, the present value P _{D (n)} of the target position calculated in step S9 or step S13 _{is set} as the previous value P _{D (n-1)} , and the previous value P _{D (n-1)} Is set as the previous value P _{D (n-2)} , and is updated and stored in predetermined storage areas of the storage device 56b, respectively, and returns to the main program.

Next, the operation of the suspension control device of this embodiment by the arithmetic processing of FIG. 15 will be briefly described.

The position attenuation force characteristic achieved by the calculation processing of Fig. 15 is equivalent to that shown in Fig. 8, and thus, steps S5 to S9 or step through steps S1 to S4 for each sampling time at which the calculation processing of Fig. 15 is executed. If P _{D (n)} is calculated as the current value of the target position in S6 to S13, then the current position P _{A is followed} by the current value P _{D (n)} of this target position in steps S15 to S24 and S22. The correlation characteristic between the vertical velocity X _2i on the spring except the dead zone and the damping force D / F is the same as that shown in FIG. 12C. Therefore, especially in the low-speed driving state of the vehicle, the soft range (SS range) in which the damping forces D / F on the extension side and the compression side are both maintained at low damping forces D / F _TO and D / F _CO with respect to the vertical speed X _2i on the small spring. Therefore, smoothness is imparted to the vehicle body behavior in the swing input region of the small vehicle body, and of course, the swing input is effectively attenuated by the damping force according to the size in the larger vehicle body swing input region.

On the other hand, when the now hold control flag F ₁ is also set ring control flag F ₂ is also referred to as the reset state 0, and also the values V readout input the vehicle speed detected at the 15 ° step S10 of the calculation process the predetermined vehicle speed value V ₀ below The flow advances to step S27 from step S14 of the arithmetic processing to steps S16 and S25. The target position P _D calculated until the calculation process is executed is fixed or increased in a constant direction, and the current position P _A follows the previous value P _{D (n-1)} of the target position. If it matches with each other, it transfers to step S28 through step S27, S29.

Here again, the setting control flag F ₂ is reset to 0 and the setting timer counter CNT ₂ is cleared, and then the hold control flag F ₁ is set in step S30. Then become the hold timer counter increasing CNT ₁ start in step S31, yet the hold timer counter CNT ₁ is a predetermined count value when said CNT is less than _zero, and a step amount S is forced to zero in step S33, the step amount of the 0 The step motor which inputs the control signal formed as a forcible state is forcibly held, and hold control is started at the same time. After that, unless the vehicle speed detection value V exceeds the predetermined vehicle speed value V ₀ , the hold control flag F ₁ is set to ₁ at step S25 from step S14 to step 16, and the flow proceeds to step S28. The flow of steps S30 to S33 and S22 is repeated for a predetermined time T ₁ until the hold timer counter CNT ₁ reaches the predetermined count value CNT ₁₀ , and the hold state of the step motor is continued for this predetermined time T ₁ to hold control. Is executed. Therefore, if the predetermined time T ₁ is sufficiently longer than the sampling time ΔT of the calculation processing of FIG. 15, the number of times equal to the predetermined count value CNT ₁₀ is generated when the step motor is followed-controlled for each sampling time ΔT. The number of times of driving and holding of the step motor is set only once in the predetermined time T ₁ , and therefore the noise evaluation of the predetermined time T ₁ is improved. In addition, even if the followability to the damping force is deteriorated in such a low-speed running state, steering stability and ride comfort are not reduced as described above. Further, of course, if the vehicle speed detection value V exceeds the predetermined vehicle speed value V ₀ , immediately following the control of the damping force for each sampling time ΔT by the flow of the step S15 to the step S24, that is, the following control of the step motor is executed. In addition, the driving stability and riding comfort in the medium and high speed driving state are improved, and at the same time, the vibration level such as road noise transmitted to the vehicle interior is high in such a medium and high speed driving state, so that the step for each sampling time ΔT is thereby achieved. The vibration level caused by the repetition of the driving and holding of the motor is masked, and the occupant is prevented from catching the operation noise of the step motor as an abnormal sound.

The hold control flag F ₁ and the set control flag F ₂ are now in the reset state of 0, and the read-input vehicle speed detection value V is less than or equal to the predetermined vehicle speed value V ₀ in step S10 of the calculation processing of FIG. 15. Then, the process proceeds to step S27 from step S14 of the arithmetic processing through steps S16 and S25. Here, as before last meeting value P _{D (n-2)} the previous value P _{D (n-1),} and in up to a tendency to increase also the previous value P _{D (n)} is decreased tendency to the target position from the target position, In such a case, or vice versa, the value from the previous position P _{D (n-2)} of the target position to the previous value P _{D (n-1)} tends to decrease, and the previous value P _{D ( In} such a case in which the value P _{D (n )} from _n-1) is changed in the increasing direction, it is necessary to switch the rotational direction of the step motor in any case. In step S27, in any case, the target position of the before last meeting value P _D value P _{D (n)} of this time from the previous value P _{D (n-1)} of subtracting the previous value P _{D (n-1)} value and a target position from the _(n-2) Since the value multiplied by the subtracted value becomes negative, the process proceeds from step S27 to step S26. Here, hold control flag F ₁ is reset to 0 again, hold timer counter CNT ₁ is cleared, and set control flag F ₂ is set in step S34. Subsequently said set ring timer increment of counter CNT ₂ started at step S35, if still the set of rings as the timer counter CNT ₂ is a predetermined car flavor CNT is less than _20, and a step amount S is forced to zero in step S33, a is 0, The step motor which inputs the control signal made as the step amount is forcibly turned to the non-rotating state, and the set control is started at the same time. After that, unless the vehicle speed detection value V exceeds the predetermined vehicle speed value V ₀ , the process proceeds from step S14 to step S16 and the setting control flag F ₂ is set to 1, so that the process proceeds to step S26 and further to step S34. The flow of steps S33 and S22 is repeated for a predetermined time T ₂ until the set timer counter CNT ₂ reaches a predetermined count value CNT ₂₀ , and the non-rotation state of the step motor continues for this predetermined time T ₂ . And setting control is executed. Therefore, if the predetermined time T ₂ is sufficiently longer than the sampling time ΔT of the calculation processing in FIG. 15, the step-down occurs as many times as the predetermined count value CNT ₂₀ when the step motor is followed-controlled for each sampling time ΔT. The number of driving and holding times of the data is only one time at the predetermined time T ₂ , and therefore the noise evaluation of the predetermined time T ₂ is improved. Even if the followability to the damping force is deteriorated in such a low-speed driving state, or if the target damping force set in any calculation process and the current damping force do not coincide, the steering stability and ride comfort are not reduced as described above.

Further, of course, if the vehicle speed detection destination V exceeds the predetermined vehicle speed value V ₀ , immediately following the control of the damping force for each sampling time ΔT by the flow of the step S15 to the step S24, that is, the following control of the step motor is executed. In the medium and high speed driving conditions, the steering stability and the riding comfort are improved, and at the same time, in such medium and high speed driving conditions, the vibration level of the road noise transmitted to the vehicle interior is large. The vibration level by the repetition of driving and holding the step motor is masked, and the occupant can avoid catching the operation noise of the step motor as an abnormal sound.

As described above, the present embodiment is considered to embody the suspension control device according to claims 1 and 2 of the present invention, and the steps S1 to S3 of the above-described vertical acceleration sensors 51FL to 51RR and the calculation processing of FIG. Corresponds to the up and down speed detecting means on the spring of the suspension control device, and similarly, the controller 4 and the entire arithmetic processing of FIG. 13 correspond to the control means, and the vehicle speed sensor 52 and the step S10 of the arithmetic processing of FIG. Steps S14, S28 to S33 of the arithmetic processing of FIG. 15 correspond to the holding time adjusting means, and steps S14, S16, S26, S33 to S36 of the arithmetic processing of FIG. 15 are non-rotating, corresponding to this vehicle speed detecting means. Corresponds to the time adjustment means.

Next, the damping force control action of the damping force variable shock absorber by the arithmetic processing of FIG. 15 will be described based on the timing chart of FIG.

Here, FIG. 16 (a) shows the time-lapse change between the target position P _D and the current position P _A , and the time-lapse change of the hold control flag F ₁ in FIG. the hold timer counter CNT ₁ time change, the figure change over time of the change over time of the new Tring control flag F ₂ to (d), set ring timer counter CNT ₂ on the diagram (e) of the figure ( f) shows the change over time of the absolute value | T | of the step motor driving force, and the change over time of the vibration level by the operation of the step motor is shown in the same figure (g).

This timing chart is based on the premise that the vehicle is traveling at a vehicle speed smaller than the predetermined vehicle speed value V ₀ . Then, the target positions P _D calculated from step S4 to step S13 in the calculation processing of FIG. 15 according to the vertical velocity X _2i detected or calculated as the road surface input or the vehicle body fluctuation input are the time t ₅₀ extension sides. Is maintained at a constant value in the area, i.e., the defining area, and then increases from time t ₅₀ to time t ₆₂ likewise in an extension-side area, i.e. at the constant area, also at a constant slope, and then from time t ₆₂ to time t ₇₀ Similarly, it is assumed that the inclination-side area, that is, the positive area, also decreases with a constant slope, and from time t ₇₀ to time _t79 , the same is also increased in the extension-side area, that is, the positive area, with a constant inclination (actual target position _PD is Estimation is set in steps for each T). On the other hand, since the target position P _D and the current position P _A coincide at the time t ₅₀ and the hold control and the set control have been canceled, after the time t ₅₁ after the sampling time? Step motor drive control is executed. Accordingly, the time until this time t ₅₁ , the driving force of the step motor is maintained in the holding state.

At this time t ₅₁ , the hold control flag F ₁ and the set control flag F ₂ are still in the reset state, and the deviation between the target position P _D and the current position P _A calculated at the sampling time t ₅₁ is zero. Since the step amount S is smaller than the maximum step amount S _MAX , the step is time from the time t ₅₁ to the next sampling time t ₅₃ from the time t ₅₁ to the time t ₅₂ after the driving time according to the step amount S. There Motor is a rotary drive, and the other hand the current position P _a is the target position P _D, to have real-time tracking as to the time t _51, and at least the time from the time t ₅₂ to the time t _53, step Motor The driving force of is maintained in the maintained state.

Also, at the next sampling time t ₅₃ , the current value P _{D (n)} of the target position is calculated in the same manner as above, but at the time t ₅₁ , the current position P _A is the previous value P _{D (n-1)} of the target position. ₎ , And the target position P _D is increasing in the same direction from the previous time to this time, so the hold control flag F ₁ is set to 1, and at the same time, the hold timer counter CNT ₁ is increased from 0 to 1. According to the arithmetic processing in Fig. 15, the step amount S, which is a control signal to the step motor, is forced to 0, so at least the sampling time ΔT from this time t ₅₃ to the next sampling time t ₅₄ is a step. The driving force of the motor is maintained in the maintained state. Here, when the predetermined count value CNT ₁₀ corresponding to the hold control the predetermined time T ₁ 4 d, the hold timer counter CNT ₁ in the next sampling time t ₅₄ a is 2, the 3 in the next sampling time t ₅₅ of Still, the predetermined count value CNT ₁₀ (= 4) is not reached, so the hold control flag F ₁ is kept in the set state of 1, and the driving force of the step motor in each sampling time DELTA T is maintained in the maintained state. do.

However, if the hold timer counter CNT ₁ is increased at the next sampling time t ₅₆ , it is equal to 4 equal to the predetermined count value CNT ₁₀ , so that the control shifts to the tracking control of the target position P _D , so that the hold control flag F ₁ is zero. The hold timer counter CNT _{1 is} also cleared at the same time as it is set. Therefore, in this case, the time from the time t ₅₁ to the time t ₅₆ corresponds to the predetermined time T ₁ . Since the step amount S calculated from the deviation between the current value P _{D (n)} and the current position P _A of the target position at this time is smaller than the positive value S _MAX of the maximum step amount, the current position P is present at this time t _{56. A} could not follow the target position P _D. Thus, the next time to the sampling time t ₅₈ from the time t _56, from t ₅₆ to the defined value S _MAX time t ₅₇ after the driving time according to the maximum step amount and step Motor the rotation drive, whereby at least for At the time from the time t ₅₇ to the time t ₅₈ , the driving force of the step motor was maintained in the holding state.

At the next sampling time t ₅₈ , as described above, the current position P _A cannot follow the target position previous value P _{D (n-1)} at the time t ₅₆ , and thus the current value P of the target position is as follows. _The following control for _{D (n)} is continued, and the step amount S calculated from the deviation between the current value P _{D (n)} of the target position and the current position P _{A at} this time is the positive value S _MAX of the maximum step amount. Since it was smaller than, it was possible to follow the current position P _A to the target position P _D at this time t ₅₈ .

Therefore, at a time from the time t ₅₈ to the next sampling time t ₆₀ , the step motor is rotationally driven from the time t ₅₈ to the time t ₅₉ after the drive time according to the step amount S, and at least the time t _At the time from ₅₉ to the time t ₆₀ , the driving force of the step motor was maintained in the holding state.

At the next sampling time t ₆₀ , the current value P _{D (n)} of the target position is calculated as described above, but at the time t ₅₈ , the current position P _A is equal to the previous value P _{D (n-1)} of the target position. Since the target position P _D is increasing in the same direction from the previous time to the present time, the hold control flag F ₁ is set to 1, and at the same time, the hold timer counter CNT ₁ is increased from 0 to 1. According to the arithmetic processing of FIG. 15, the step amount S, which is a control signal to the step motor, is forced to 0, so that at least the sampling time DELTA T from this time t ₆₀ to the next sampling time t ₆₁ is the step motor. The driving force of is maintained in the maintained state. The hold timer counter CNT ₁ in the next sampling time t ₆₁ a is 2, and only then at the sampling time t ₆₂ is the third of the not yet to the predetermined count value CNT ₁₀ (= 4), thus the hold control flag F ₁ is maintained in the set state of 1, and the driving force of the step motor in each sampling time DELTA T is maintained in the maintained state.

However, when the hold timer counter CNT ₁ is increased at the next sampling time t ₆₃ , it becomes 4 equal to the predetermined count value CNT ₁₀ , so that the control shifts to the tracking control of the target position P _D , so that the hold control flag F ₁ is 0. The hold timer counter CNT _{1 is} also cleared. Therefore, in this case, the time from the time t ₅₈ to the time t ₆₃ corresponds to the predetermined time T ₁ . The current value P _{D (n)} of the target position at this time is starting to decrease from the previous time t ₆₂ , and the current value P _{D (n)} and the current position P _A of the target position which is still decreasing. Since the step amount S calculated from the deviation from is smaller than the positive value S _MAX of the maximum step amount, the current position P _A can be tracked to the target position P _D at this time t ₆₃ . Therefore, at a time from the time t ₆₃ to the next sampling time t ₆₅ , the step motor rotates from the time t ₆₃ to the time t ₆₄ after the drive time according to the step amount S, and at least the time t _At the time from ₆₄ to the time t ₆₅ , the driving force of the step motor was maintained in the holding state.

At the next sampling time t ₆₅ , the current value P _{D (n)} of the target position is calculated as described above, and at the time t ₆₃ , the current position P _A is equal to the previous value P _{D (n-1)} of the target position. The target position P _D, which coincides with and starts to decrease from the previous sampling time t ₆₂ , continues to decrease in the same direction from the previous time to this time, so that the hold control graph F ₁ is set to 1 and the hold timer counter CNT ₁ is set at the same time. Incremented from 0 to 1. According to the arithmetic processing of FIG. 15, the step amount S, which is a control signal to the step motor, is forced to 0, so that the sampling time DELTA T from this time t ₆₅ to the next sampling time t ₆₅ is determined by the step motor. The driving force is maintained in the holding state, and at the next sampling time t ₆₆ , the hold timer counter CNT ₁ becomes 2, and the next sampling time t ₆₇ becomes 3, yet the predetermined count value CNT ₁₀ (= 4) Therefore, the hold control flag F ₁ is therefore kept in the set state of 1, and the driving force of the step motor in each sampling time DELTA T is maintained in the holding state.

However, if the hold timer counter CNT ₁ is increased at the next sampling time t ₆₈ , it becomes 4, which is equal to the predetermined count value CNT ₁₀ , so that the control shifts to the tracking control of the target position P _D , so that the hold control flag F ₁ becomes zero. At the same time as the reset, the hold timer counter CNT _{1 is} also cleared. Accordingly, here, it is the time t ₆₃ after a target position of time until a time t ₆₈ from the tracking control the time t _63, to the even times of the P _D corresponding to the predetermined time T _1. Then, the step amount S calculated from the deviation between the current value P _{D (n)} of the target position at this time t ₆₈ and the current position P _A , which is still decreasing in the same direction, is the negative value of the maximum step amount (− S _MAX ), the current position P _A could not be tracked to the target position P _D at this time t ₆₈ . Therefore, at a time from the time t ₆₈ to the next sampling time t ₇₀ , the step motor is rotationally driven from the time t ₆₈ to the time t ₆₉ after the driving time according to the negative value (-S _MAX ) of the maximum step amount. On the other hand, at least from the time t ₆₉ to the time t ₇₀ , the driving force of the step motor was maintained in the holding state.

At the next sampling time t ₇₀ , as described above, the current position P _A cannot be followed by the previous value P _{D (n-1)} of the target position at the time t ₆₈ , and thus, the current value of the target position. The following control for P _{D (n)} is continued, and the step amount S calculated from the deviation between the current value P _{D (n)} of the target position and the current position P _{A at} this time is the positive value S _MAX of the maximum step amount. Since it was smaller than, it was possible to follow the current position P _A to the target position P _D at this time t ₇₀ . Therefore, at the time from the time t ₇₀ to the next sampling time t ₇₂ , the step motor is rotationally driven from the time t ₇₀ to the time t ₇₁ after the driving time according to the step amount S, and at least the time t _At the time from ₇₁ to the time t ₇₀ , the driving force of the step motor was maintained in the holding state.

By the way, in the following control of the target position P _D at the time t ₇₀ , as described above, the target position P _D is changed from decreasing to increasing although it is the same defined area. In such a case, that is, when the rotation direction of the step motor is switched, it is not necessarily the following from the influence of the chopping control of the current position P _A of the actual step motor, but due to the influence of the rotational inertia of the rotor, If the direction is immediately changed to the rotation direction, as described above, the current position P _A calculated by the accumulation and the true current position may fluctuate, which may lead to a so-called outgrowing state. Therefore, in order to prevent out-of-step intrinsically, the set time in which the rotation direction is switched after the step motor stops is set. This set time, that is, the non-rotation time during which the step motor does not rotate, is forcibly lengthened in the low-speed traveling state in the setting control of the present embodiment.

Thus, at time t ₇₀ described above, but the current position P _A is coincides with the target position P _D, although the current position P _A is the target position in the P _D and do not have to match, then the sampling time t _72, the pre-war conference sampling time t _The value obtained by subtracting the target position P _{D (n-1)} at the previous sampling time t ₇₀ from the target position P _{D (n-2)} at ₆₆ , and similarly to the target position P _{D (n} at the previous sampling time t _{70 -1)} is multiplied by the value obtained by subtracting the target position P _{D (n)} at the time t _72. Therefore, in the arithmetic processing of FIG. 15, the setting control flag F ₂ is set to 1 and simultaneously set. The timer counter CNT ₂ is increased from 0 to 1. According to the arithmetic processing in Fig. 15, the step amount S, which is a control signal to the step motor, is forced to 0, so that the sampling time DELTA T from this time t ₇₂ to the next sampling time t ₇₃ is the step motor. The driving force of is maintained in the maintained state. Here, the set of rings a predetermined time when said predetermined count value CNT ₂₀ 4 corresponding to T _2, the set ring timer counter CNT at the following sampling time t ₇₃ of Figure _2, and the second, at the next sampling time t ₇₄ a 3 However, since the predetermined count value CNT ₂₀ (= 4) has not yet been reached, the set control flag F ₂ is therefore kept in the set state of 1, and the driving force of the step motor at each sampling time DELTA T is maintained. Lasts.

However, when the set timer counter CNT ₂ is increased at the next sampling time t ₇₅ , the set timer counter CNT ₂ is equal to 4 equal to the predetermined count value CNT ₂₀ , so that the control shifts to the tracking control of the target position P _D , and therefore the setting control flag F _2. Is set to 0 and the setting timer counter CNT _{2 is} also cleared. After, in this case, the time until a time t ₇₅ from the above time t ₇₀ corresponds to the predetermined time T _2. Then, the step amount S calculated from the deviation between the current value P _{D (n)} of the target position at this time t ₇₅ and the current position P _A , which is still increasing in the same direction, is the positive S _MAX value of the maximum step amount. Since it was larger than this, the current position P _A could not be followed by the target position P _D at this time t ₇₅ . Therefore, at a time from the time t ₇₅ to the next sampling time t ₇₇ , the step motor is rotationally driven from the time t ₇₅ to the time t ₇₆ after the drive time according to the positive value S _MAX of the maximum step amount. At least, from the time t ₇₆ to the time t ₇₇ , the driving force of the step motor was maintained in the holding state.

At the next sampling time t ₇₇ , as described above, the current position P _A cannot be followed by the previous value P _{D (n-1)} of the target position at the time t ₇₅ , and thus, the current value of the target position. The following control for P _{D (n)} is continued, and the step amount S calculated from the deviation between the current value P _{D (n)} of the target position and the current position P _{A at} this time is the positive value S of the maximum step amount. Since it was smaller than _MAX , it was possible to follow the current position P _A to the target position P _D at this time t ₇₇ . Therefore, at a time from the time t ₇₇ to the next sampling time t ₇₉ , the step motor is rotationally driven from the time t ₇₇ to the time t ₇₈ after the driving time according to the step amount S, and at least the time t _At the time from ₇₈ to the time t ₇₉ , the driving force of the step motor was maintained.

At the next sampling time t ₇₉ , the current value P _{D (n)} of the target position is calculated as described above, but at the time t ₇₇ , the current position P _A is equal to the previous value P _{D (n-1)} of the target position. Since the target position P _D continues to increase in the same direction from the previous time to the present time, the hold control flag F ₁ is set to 1, and at the same time, the hold timer counter CNT ₁ is increased from 0 to 1 at the same time. The step amount S, which is a control signal to the motor, is forced to zero, and the hold control is started.

Therefore, according to the suspension control apparatus of the present embodiment, since the clockwise rotation in which the position increases is defined as the rotation in the forward direction and the counterclockwise rotation in which the position is reduced, the rotation in the negative direction is, for example, Even if the driving force T of the step motor required for rotation is a positive value and the driving force T of the step motor required for the negative rotation is shown as a negative value, the absolute value of the driving force of the step motor for each sampling time ΔT | T | Appears as shown in FIG. That is, the absolute value | T | of the driving force of the step motor becomes a driving state and appears in a rectangular wave shape from the time t ₅₁ during the target position following control time in which the hold control and the set control are not executed. Time t ₅₂ , time t ₅₆ from time t ₅₆ , time t ₅₉ from time t ₅₈ , time t ₆₄ from time t ₆₃ , time t ₆₉ from time t ₆₈ , time t ₇₁ from time t ₇₀ , time t ₇₁ from time t ₇₅ The total of eight driving time points from ₇₆ and time t ₇₇ to time t ₇₈ is further distributed. Moreover, since these driving times are dispersed with each other, the vibration level in the holding state time between them becomes a sufficiently small value, and from time t ₅₀ to time t The average value of the noise energy up to ₇₉ is smaller than that in the case where the target position tracking control is always performed at each sampling time, and the noise evaluation is improved.

Incidentally, in the above embodiment, only the case where the target position changes abruptly for the sake of easy understanding, the target position for achieving the damping force in the actual vehicle does not change so rapidly, however, It goes without saying that the suspension control apparatus of the present invention achieves the tracking control of the target position in almost the same manner as described above.

In the above embodiment, the case in which the valve body 31 for controlling the damping force is configured in the rotary type has been described. However, the present invention is not limited thereto, and the spool type is used to provide different flow paths on the compression side and the extension side. In this case, the pinion is connected to the rotating shaft 41a of the step motors 41FL to 41RR, and the rack engaged with the pinion is mounted on the connecting rod 42 or an electromagnetic solenoid is applied. The sliding position of the valve body 31 may be controlled.

In the above embodiment, the case where the sky hook approximate control is performed in which the vertical acceleration of the vehicle body is detected and the damping force is controlled accordingly is described. However, the present invention is not limited thereto, and the relationship between the vehicle body and the wheels is not limited thereto. installing the stroke size (stroke) sensor for detecting the displacement separately, and to the basis of the stroke size sensor body vertical velocity X _2i described the relative displacement detected value X _Di ahead and a relative speed X _Di derivative of the calculation of the expression 7 The damping coefficient C may be calculated, and the target position may be calculated by referring to a map corresponding to FIG. 8 based on the damping coefficient C, for example, to perform skyhook control.

_{C = C S · X 2i /} X Di

However, C _S is a damper damping coefficient set in advance.

In the above embodiment, the case where the change in the attitude of the vehicle body due to the vibration input from the road surface is suppressed, but the present invention is not limited thereto, and the driving state such as the braking state of the vehicle is detected, thereby changing the attitude of the vehicle body. The control may be performed together with the restraint.

In the above embodiment, the case where the microcomputer 56 is applied and controlled has been described. However, the present invention is not limited thereto, and electronic circuits such as arithmetic circuits may be combined.

In the above embodiment, the case where the vertical acceleration sensors 51FL to 51RR are provided at the positions of the wheels 1FL to 1RR of the vehicle body 2 has been described, but any one of the vertical acceleration sensors is omitted and omitted. The up and down acceleration of the position may be estimated from the values of other up and down acceleration sensors.

As described above, according to the suspension control device according to the present invention, when the target rotational position of the step motor and the current rotational position coincide in the low-speed driving state where the level of road noise or the like transmitted to the vehicle interior is small. By increasing the step motor holding time, it is possible to shorten the driving time of the step motor or to reduce the driving frequency, thereby reducing the noise generation time and the frequency of the high vibration level. As a result, the overall noise energy is reduced. The noise evaluation is improved. Further, even if the target rotational position of the step motor is increased and decreased in detail, and the target rotational position of the step motor does not coincide with the current rotational position, the non-rotation time when the rotational direction of the stepped motor is changed is increased. Therefore, the driving time of the step motor can be shortened or the driving frequency can be shortened to reduce the generation time or the frequency of the occurrence of high vibration level noise. As a result, the overall noise energy can be reduced to improve the noise evaluation. Of course, even if the trackability to the target damping force is slightly reduced in such a low speed driving state, the steering stability and the riding comfort are not significantly reduced.

Claims (2)

The position of the valve body is controlled by the rotation of the step motor mounted between the vehicle body side member and the wheel side member and driven according to the input control signal, so that the damping force of either the extension side or the compression side is set large or both sides. A damping force variable shock absorber capable of setting a small damping force, an up / down speed detecting means for detecting the body behavior related to the up and down speed on the spring of the vehicle body, and at least a up / down speed detecting value on the spring detected by the up / down speed detecting means on the spring. Control means for calculating a damping force for suppressing a change in attitude of the vehicle body and outputting the control signal to the step motor so that the actual position of the valve body matches the target position of the valve body corresponding to the damping force. A suspension control device comprising: a vehicle speed detecting means for detecting a front-rear speed of a vehicle; The control means does not rotate the step motor when the actual position of the valve body matches the target position of the valve body when the vehicle speed detection value detected by the vehicle speed detecting means is equal to or less than a predetermined predetermined vehicle speed value. Suspension control device characterized in that it comprises a holding time adjusting means for adjusting the holding time is not long. The vehicle control apparatus according to claim 1, wherein the step motor is controlled to be rotated in a certain order direction and its reverse direction according to the control signal, and the control means is configured such that when the vehicle speed detection value detected by the vehicle speed detection means is equal to or less than a predetermined vehicle speed value, Non-rotation time adjusting means for adjusting the non-rotation time during which the step motor does not rotate when the rotation direction of the step motor is changed to match the actual position of the valve element with the target position of the valve element. Suspension control device characterized in that.