JP3156480B2 - Suspension control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension control device for performing a so-called semi-active control in which a damping force is controlled based on a displacement speed of a vehicle body and a relative speed between the vehicle body and wheels.

[0002]

2. Description of the Related Art A conventional suspension control device is disclosed in, for example, Japanese Patent Application Laid-Open No. 3-42319. In this conventional example, by inputting a control signal,
A shock absorber capable of changing the extension-side damping force and the compression-side damping force to at least low damping force and high damping force, respectively, sprung speed measuring means for measuring sprung speed, and relative speed between sprung and unsprung , A sign determining means for determining whether the sign of the sprung speed and the sign of the relative speed match or not, and when the signs match and the sign of the relative speed is positive, A control signal that sets the extension side to high damping force, the compression side to low damping force, and when both signs match and the sign of the relative speed is negative, the extension side has low damping force and the compression side has high damping force. Is output. On the other hand, when both codes do not match,
Control signal output means for outputting a control signal for setting both the compression side to a low damping force.

[0003]

However, in the above-mentioned conventional suspension control device, the damping force is determined by the sign of the sprung speed and the relative speed, and the damping force is increased on the extension side.
The compression side is set to low damping force, the extension side is set to low damping force, the compression side is set to high damping force, and furthermore, it is controlled to three modes in which both the extension side and the compression side have low damping force. There is an unsolved problem that the optimal damping effect cannot be exerted at all sprung speeds because the damping force at is not fixed to a constant value.

In order to solve this unsolved problem, the target damping coefficient is set in proportion to the sprung speed,
It is conceivable to perform skyhook approximation control. In this case, when the control gain is determined according to the magnitude of a predetermined vibration input, the damping coefficient is set to a small value for an input smaller than the vibration input. Therefore, there is a new problem that a large vibration suppression effect cannot be exerted and the vehicle body becomes fluffy, which impairs ride comfort.

Accordingly, the present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to provide a suspension control device capable of exhibiting an optimal vibration damping effect in all regions of sprung speed. The purpose is.

[0006]

According to a first aspect of the present invention, there is provided a suspension control apparatus interposed between a vehicle body-side member and a wheel-side member, as shown in FIG. A suspension device capable of changing a damping force in accordance with a control signal input thereto, a vertical acceleration detecting device for detecting a sprung vertical acceleration at the position of the suspension device, and at least a sprung portion of the vertical acceleration detecting device A control unit for forming and outputting the control signal for suppressing a change in the posture of the vehicle body based on the sprung vertical speed obtained by integrating the detected vertical acceleration value, the control unit comprising: Based on speed
The gain for computing the damping coefficient Zui, the in the region on the vertical velocity is equal to or greater than the set value spring is set to a predetermined value, lower than the vertical velocity on the spring setting value in the region sprung mass vertical velocity is smaller than the set value And a gain setting means for setting the value to increase as the value increases.

According to a second aspect of the present invention, in the above configuration, the gain setting means sets a gain for calculating the damping coefficient to a predetermined value when the sprung vertical speed is equal to or more than a set value. In a region where the sprung vertical speed is smaller than the set value, the sprung vertical speed is set to increase linearly as the sprung vertical speed decreases below the set value.

[0008]

In the suspension control device according to the first aspect, the gain setting means calculates the damping coefficient based on the sprung vertical speed in a region where the vertical speed of the vehicle body is small .
By setting a large gain for this purpose, it is possible to set the damping coefficient in a region where the vertical velocity is smaller than the set value to a large value, and to improve the vibration damping effect in this region.

In the suspension control device according to the second aspect, the control gain is linearly increased from a set value in accordance with a decrease in the sprung vertical speed in a region where the vertical speed is small, that is, the control gain is inversely proportional to the sprung vertical speed. In the region where the spring vertical velocity is large, the gain is set to a constant value. Therefore, the gain can be changed to an optimum value according to the change in the spring vertical velocity, and a good vibration damping effect is exhibited.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a schematic configuration diagram showing one embodiment of the present invention, in which a variable damping force shock absorber 3 constituting a suspension device is provided between each wheel 1FL-1RR and the vehicle body 2.
FL to 3RR are arranged, and a stepping motor 41 for switching the damping force of these variable damping force shock absorbers 3FL to 3RR is provided.
FL to 41RR are controlled by a control signal from a controller 4 described later.

Variable damping force shock absorber 3FL-3RR
Is a twin-tube gas-filled strut type having a cylinder tube 7 composed of an outer cylinder 5 and an inner cylinder 6 as shown in FIGS. 8 define upper and lower pressure chambers 9U and 9L. 4 to 7, the piston 8 has a cylindrical lower half 11 having a sealing member 9 molded on the outer peripheral surface thereof in sliding contact with the inner cylinder 6 and having a center opening 10 on the inner peripheral surface. The lower half 11 has an upper half 12 fitted therein.

The lower half 11 has an extension oil passage 13 penetrating vertically and a sealing member 9 extending downward from the upper surface.
The hole 14 a having a diameter larger than that of the extension-side oil flow path 13 and extending from the outer peripheral surface of the cylindrical body 11 to the hole 14.
a, a pressure-side oil flow path 14 formed of a hole 14b drilled in communication with the bottom of the hole a, annular grooves 15U, 15L formed at the upper and lower open ends of the central hole 10, and formed on the upper surface side. A long groove 16 communicating with the annular groove 15U and the expansion-side oil flow path 13 and a long groove 17 formed on the lower surface side and communicating with the annular groove 15L are formed. The long groove 17 is closed by the extension-side disk valve 18, and the upper end side of the compression-side oil flow path 14 is closed by the compression-side disk valve 19.

The upper half 12 has a small-diameter shaft 21 inserted into the center opening 10 of the lower half 11,
The lower end face of the small-diameter shaft portion 21 is formed at the center of the small-diameter shaft portion 21 and the large-diameter shaft portion 22. 23a extending from the side to the middle part of the large-diameter shaft portion 22, and a hole 23b communicating with the upper end side of the hole 23a and having a smaller diameter than this.
And a hole 23c having a larger diameter than the hole 23c communicating with the upper end side of the hole 23b is formed. Pair of through holes 24 penetrating in the direction toward the inner peripheral surface side
a, 24b and 25a, 25b are drilled, and the upper end side of the hole 23a of the large-diameter shaft portion 22 is connected to the arc-shaped groove 2 communicating therewith.
6 is formed, and an L-shaped pressure-side oil flow path 27 that communicates the arc-shaped groove 26 with the lower end face is formed.
Is blocked by

The lower half 11 and the upper half 12 are positioned below the lower half 11 of the small-diameter shaft 21 with the small-diameter shaft 21 inserted into the central opening 10 of the lower half 11. The nut 29 is screwed into the lower end protruding from the nut, and the nut 29 is tightened to be integrally connected. Further, a cylindrical valve body 31 whose upper end is closed in a hole 23a of the upper half body 12 and constitutes a variable throttle is rotatably disposed. As shown in FIG. 4, the valve body 31 has an upper half 1
2, a through-hole 32 is formed at a position facing the arc-shaped groove 26 of the large-diameter shaft portion 22 so as to reach the inner peripheral surface in the radial direction, and as shown in FIGS. A communication groove 33 is formed in the outer peripheral surface corresponding to the portion between the through holes 24a and 24b of the portion 21 to communicate them with each other. Further, as shown in FIG.
And 25b, an elongated hole 34 extending in the axial direction is formed on the outer peripheral surface corresponding to the inner peripheral surface side.
Then, the positional relationship between the through hole 32, the communication groove 33 and the long hole 34 is selected so as to obtain the damping force characteristic with respect to the rotation angle of the valve body 31 shown in FIG. ing.

That is, at the position A in FIG. 8, which is the maximum rotation angle position in the clockwise direction when viewed from the plane, only the through hole 32 communicates with the arc-shaped groove 26 as shown in FIG. Moves downward from the lower pressure chamber 9L through the pressure-side oil flow path 14 to the upper pressure chamber 9U through an orifice formed by the open end and the pressure-side disk valve 19. Channel C
1 through the inner peripheral surface of the valve body 31 from the lower pressure chamber 9L, through the through hole 32, the arc-shaped groove 26, the pressure side oil flow path 27, and through the orifice formed by the opening end and the pressure side disc valve 28. Pressure side flow path C2 shown by a broken line toward the upper pressure chamber 9U.
Is formed and the piston 8 moves upward on the extension side, the orifice formed by the open end and the extension side disc valve 18 from the upper pressure chamber 9U through the elongated groove 16 and the extension side flow path 13. Only the extension side flow path T1 shown by a broken line toward the lower pressure chamber 9L is formed, and a high damping force that rapidly increases in accordance with an increase in the piston speed is generated on the extension side, and is increased on the compression side. Generates a low damping force that increases slightly as the piston speed increases.

By rotating the valve element 31 counterclockwise from this position A, as shown in FIG.
1 communication groove 33 and through holes 24a, 25a of small diameter shaft portion 21
Are in communication with each other, and the communication groove 33
And the opening area of the through holes 24a and 25a gradually increases. Therefore, the movement of the piston 8 on the extension side is not shown in FIG.
As shown in (a), the long groove 16, the annular groove 15U, the through hole 24a, the communication groove 33, the through hole 24 are arranged in parallel with the flow path T1.
b, a flow path T2 that passes through the annular groove 15L and the long groove 17 and passes through the orifice formed by the long groove 17 and the pressure-side disc valve 18 toward the lower pressure chamber 9L is formed.
As shown in FIG. 8, the maximum value of the damping force gradually decreases as the opening area between the communication groove 33 and the through holes 24a and 25a of the small-diameter shaft portion 21 increases. 5 (b)
As shown in (2), in order to maintain the state where the flow paths C1 and C2 are formed, the state of the minimum damping force is maintained.

Further, when the valve body 31 is rotated counterclockwise as viewed from a plane and becomes near the position B, as shown in FIG. 6, an elongated hole 34 is formed between the through holes 25a and 25b of the valve body 31.
The communication is established. Therefore, the piston 8
As shown in FIG. 6 (a), the lower side passes through the long groove 16, the annular groove 15U, the through hole 25a, the long hole 34, and the hole 23a in parallel with the flow paths T1 and T2. 9L pressure chamber
Is formed, the extension-side damping force becomes the minimum damping force state, and the hole 23a and the long hole are provided for the movement of the piston 8 on the compression side in addition to the channels C1 and C2. 34, the through-hole 25b, the long groove 1 through the annular groove 15U.
6, the flow path C3 and the hole 23a, the long hole 34, the through hole 25b, the annular groove 15L, the through hole 24b, the communication groove 33,
A flow path C4 that reaches the long groove 16 through the through hole 24a and the annular groove 15U is formed, but maintains the minimum damping force state as shown in FIG.

Further, when the valve element 31 is rotated counterclockwise as viewed from a plane, the long hole 34 and the through holes 24b and 25b
And the opening area between the hole 34 and the long hole 34 at the rotation angle θ _B2 is reduced.
7, the opening area between the through hole 32 and the arc-shaped groove 26 gradually decreases from the rotation angle θ _B2 . Therefore, between the rotation angle θ _B2 and the maximum counterclockwise rotation angle θ _C ,
For the movement of the piston 8 on the extension side, the flow path T1 and T2 coexist, so that the minimum damping force state is maintained. Conversely, for the movement of the piston 8 on the compression side, the connection between the through hole 32 and the arc-shaped groove 26 is made. When the opening area therebetween gradually decreases, the maximum damping force gradually increases, and when the valve element 31 reaches the position C, as shown in FIG. By being in the cutoff state, the flow path from the lower pressure chamber 9L to the upper pressure chamber 9U is only the flow path C1 with respect to the pressure side movement of the piston, and the pressure side is in a high damping force state.

On the other hand, a cylindrical piston rod 35 is fitted into the hole 23c of the upper half body 12, and the upper end of the piston rod 35 projects upward from the cylinder tube 7, as shown in FIG. The upper end side is the vehicle body side member 36.
Is fixed to a bracket 37 attached to the bracket 37 via nuts 39 via rubber bushes 38U and 38L.
The rotating shaft 41a and the above-described valve body 31 are connected by a connecting rod 42 loosely inserted into the piston rod 35. 43 is a bumper rubber. The lower end of the cylinder tube 7 is connected to a wheel-side member (not shown).

The controller 4 has an input side as shown in FIG.
As shown in the figure, according to the vertical acceleration provided on the vehicle body side corresponding to each wheel position, the vertical acceleration detection values X _2FL ″ -X composed of analog voltages that are positive in the upward direction and negative in the downward direction
Vertical acceleration sensors 51FL to 51RR as vertical acceleration detecting means for outputting _2RR "are connected. Step motors 41FL to 41RR for controlling the damping force of each damping force variable shock absorber 3FL to 3RR are connected to the output side.

The controller 4 includes a microcomputer 56 having at least an input interface circuit 56a, an output interface circuit 56b, an arithmetic processing device 56c and a storage device 56d;
An A / D converter 57FL~57RR supplied to the input interface circuit 56a FL～51RR the vertical acceleration detection value X _2FL "~X _2RR" is converted into a digital value, each step motor which is output from the output interface circuit 56b 41
A step control signal for FL to 41RR is input, and is converted into a step pulse to convert each step motor 41FL to 41RR.
The motor drive circuits 59FL to 59RR for driving the 41RR are provided.

Here, the arithmetic processing unit 56c of the microcomputer 56 calculates the detected vertical acceleration X _2FL ″ of the vehicle body input from the vertical acceleration sensors 51FL to 51RR.
By integrating the X _2RR "calculates the vehicle body vertical velocity X _2FL '~X _2RR', the vehicle body vertical velocity X _2FL '~X _2RR'
Coefficient for performing skyhook approximation control with reference to a control map stored in advance in the storage device 56d based on
Calculating a target step angle theta _TFL through? _TRR step motor 41FL~41RR corresponding to the determined attenuation coefficient C is calculated, the target step angle theta _TFL through? _TRR and the current step angle theta _PFL through? _{PR R} is calculated, and the step control amounts S _{FL to} S _RR corresponding to the difference value are calculated by the motor drive circuit 59FL.
Output to ~ 59RR.

The storage device 56d stores the arithmetic processing device 5
A program necessary for the arithmetic processing of FIG. 6c is stored in advance, necessary values in the arithmetic processing process and the calculation result are sequentially stored, and a control map shown in FIG. 11 is stored in advance. As shown in FIG. 11, when the vertical axis represents the vehicle vertical velocity X _2i ′ and the vertical axis represents the damping coefficient C, the control map indicates that the vehicle vertical velocity X _2i ′ is smaller than the set value X _2S ′.
As the vehicle vertical speed X _2i ′ increases from zero, the general formula C
² = 4aX _2i ′.
'In the above areas, the vehicle body vertical velocity X _{2i' 2S} represented by characteristic curve L ₁ extending in proportion to the increase of the linear, thus, in the vehicle body vertical velocity X _2i 'set value X _2S' smaller area The control gain α is set to a large value, and the control gain α is set to a small constant value in a region where the vehicle body vertical speed X _2i ′ is larger than the set value X _2S ′.

Next, the operation of the above embodiment will be described with reference to FIG. 10 showing an example of the processing procedure of the arithmetic processing unit 56c of the microcomputer 56. That is, the process of FIG. 10 is executed as a timer interrupt process at predetermined time intervals (for example, 10 msec). First, at step S1, each vertical acceleration detection value X
_2i "is read, and then the process proceeds to step S2, where the vertical acceleration detection value _X2i " read in step S1 is integrated by, for example, low-pass filtering to calculate a vehicle vertical speed _X2i ', and these are stored. 11 is temporarily stored in a predetermined storage area of the device 56d, and then proceeds to step S3 to refer to the control map of FIG. 11 stored in the storage device 56d based on the vehicle body vertical speed X _2i ′ calculated in step S2. to, calculates the skyhook approximation control damping coefficients C _i.

Next, the process proceeds to step S4, where it is determined whether the damping coefficient C calculated in step S3 is equal to or less than a predetermined minimum damping force C _MIN of the variable damping force shock absorber 3i. _{If i} > _CMIN , the process proceeds to step S5 to determine whether or not the vehicle body vertical speed _X2i 'is positive. If _X2i '> 0, the process proceeds to step S6 and proceeds to step S3. in to set the calculated damping coefficient C _i with the extension side, the target step angle theta with reference to the region of the theta _a through? _B1 of the control map corresponding to FIG. 8
After calculating _Ti , the process proceeds to step S7.

In step S7, the current step angle θ _Pi and the target step angle θ stored in the storage device 56d are set.
With calculating a deviation between the _Ti, which is updated and stored in a predetermined storage area of the storage device 56d as step control quantity S _i,
Wherein the target step angle theta _Ti currently updated and stored as the step angle theta _Pi, then the process proceeds to step S8, outputs the step control amount S _i which is stored in a predetermined storage area of the storage device 56d to the motor drive circuit 59i After that, the timer interrupt processing ends and the process returns to the predetermined main program.

The result of the determination in step S5 is X _2i '<
When it is 0, the process proceeds to step S9, the damping coefficient C _i calculated in the step S3 to set in the compression, with reference to the region of the theta _B2 through? _C of the corresponding control map in FIG. 8 target After calculating the step angle θ _T , the process proceeds to step S7. Further, the determination result of step S4 is
If C _i ≦ C _MIN , the process proceeds to step S10 to calculate the target step angle θ _Ti by referring to the region of θ _B1 to θ _{B2 in} the control map corresponding to FIG. 8, and then proceeds to step S7. I do.

The processing in FIG. 10 corresponds to the control means, and among them, the processing in step S3 corresponds to the gain setting means. Therefore, when the vehicle is traveling straight on a flat good road, there is almost no vertical movement of the vehicle body. Therefore, the vertical acceleration detection values X _2FL ″ to X _2RR ″ output from the vertical acceleration sensors 51FL to _51RR are It becomes almost zero.

Therefore, when the process of FIG. 10 is executed, the vehicle body vertical speed X _2FL 'calculated in step S2.
Since X _2RR ′ is also substantially zero, and the damping coefficient C _i calculated in step S3 is also substantially zero, the process proceeds from step S4 to step S10, where the extension-side and compression-side minimum damping coefficients C _i are determined.
A step angle within the range of the step angles θ _{B1 to} θ _B2 that becomes _nMIN and _CaMIN is set as a target step angle θ _Ti , and the step motors 41FL to 41RR are driven such that the step angles coincide with the target step angle θ _Ti. Is done. For this reason, the valve element 31 of the damping force variable shock absorbers 3FL to 3RR is configured as shown in FIG.
Is set to position B shown in, thereby, the damping coefficient C _i of the extension side and the compression side of the piston 8 is set to each minimum damping coefficient C _Nmin and C _Amin. Therefore, in this state, even if vibrations due to fine irregularities on the road surface are input to the wheels, the vibrations are absorbed by the damping force variable shock absorbers 3FL to 3RR and are not transmitted to the vehicle body, so that a good ride comfort can be secured. .

If the vehicle does not move up and down due to the passage of a temporary step such as a step rising forward in this good road running state, the vehicle vertical speed X
_{Since 2FL} 'to _X2RR ' maintain zero, the minimum damping coefficient C
_In order to maintain the _aMIN and _CnMIN states, it is possible to absorb the pushing force when the wheel rides on the step, but when the vehicle rides on a relatively large step and cannot absorb the pushing force, the vehicle body It would be displaced upward, thus resulting in the vehicle body vertical velocity X _2FL '~X _2RR' is increased in the positive direction.

As described above, the vehicle body vertical speed X _2FL ′ -X
_{When 2RR} 'increases in the positive direction, the _{process proceeds to} step S6, where the damping coefficient C _{i in} the region of the step angles θ _{A to} θ _{B1 in} FIG.
Is calculated according to the target step angle θ _Ti , the switching of the valve elements 31 of the damping force variable shock absorbers 3FL to 3RR is controlled as shown in FIG. As a result, when the displacement speed X _1i ′ on the wheel side is faster than the displacement speed X _2i ′ on the vehicle body side due to the stepping over and the piston 8 moves to the _compression side, the _compression- side minimum damping coefficient _CaMIN is maintained. Therefore, the vibration input to the wheel side can be absorbed, and when the climbing speed on the wheel side becomes lower than the climbing speed on the vehicle body side by going over the step from this state, the piston 8 moves to the extension side.

At this time, since the damping coefficient C _i becomes a large value, a damping effect for suppressing the rise of the vehicle body is exerted, and when the vehicle body stops rising thereafter, the vehicle vertical speed X _2FL 〜.
When X _{2R R} ′ becomes zero, the step motors 41FL to 41RR are rotated counterclockwise and returned to the position B as described above, whereby both the _compression side and the expansion side have the minimum damping coefficients _CaMIN and _CnMIN. Then, when the vehicle body starts descending, the vehicle body vertical speeds X _2FL ′ to X _2RR ′ increase in the negative direction in response thereto, and the process shifts from step S8 to step S12 to _execute the control map of FIG. see by calculating the target step angle theta _Ti corresponding to the damping coefficient C _i in the range of the step angle theta _B2 through? _C and the valve body 31 is further rotated in the counterclockwise direction, shown in FIG. 7 It is turned to the turning position. For this reason, the body descends,
In the state where the piston 8 moves to the pressure side, the damping force is increased, so that a large damping effect is exhibited.

Conversely, when the wheel passes through a step descending forward
First, the wheels rebound, causing the piston
8 moves to the extension side, but the body does not move up and down at this time.
So the body vertical speed X_2FL'~ X_2RR′ Is zero
And the damping force of the variable shock absorbers 3FL to 3RR
The number is the minimum damping coefficient C_aMINAnd C_nMINKeep the wheels under
Allow the descent, and then when the vehicle starts descending,
Lower speed X_2FL'~ X_{2R R}′ Increases in the negative direction and the damping coefficient
C_iBecomes a large value, and the step angle θ_B2~ Θ _CRange
Target step angle θ_TiIs calculated, and the valve element 3
1 is rotated to the position shown in FIG.
Gives a large damping force to the movement on the side, and a large damping effect
Fruit can be demonstrated.

Thereafter, the vehicle vertical speed X_2FL'~ X_2RR′
Becomes smaller and the damping coefficient C_iAs the valve becomes smaller
The body 31 is rotated clockwise and returns to the position B side,
Body vertical speed X_2FL'~ X_2RR′ Becomes zero, the valve element 3
1 becomes the position B and the minimum damping coefficient C_aMINAnd C
_nMINBecomes After that, the car body started to rise by swinging back
When you start, the vehicle body vertical speed X_2FL'~ X_2RR′ In the positive direction
With the increase, the piston 8 moves to the extension side.
The damping coefficient C_iStep angle θ with increasing _AWith the side
Target step angle θ_TiIs calculated, and the valve body 31 moves clockwise.
By turning to the position shown in FIG.
A large damping force is applied to the movement of the
A vibration effect can be exhibited.

As described above, when the vehicle travels on a temporary step while traveling on a good road, a good vibration damping effect can be exerted by the skyhook approximation control, and the vehicle travels on a bad road. In this case, the target step angle θ _Ti on the step angle θ _A side (or the step angle θ _C side) is calculated based on the positive (or negative) of the vehicle body vertical speeds X _2FL ′ to X _2RR ′, thereby raising the vehicle body. and minimum attenuation coefficient damping coefficient C _i when the piston 8 or body piston 8 moves pressure side is lowered is vibration direction moves to the extension side and C _Amin and C
_{When the} vehicle body moves upward and the piston 8 moves to the extension side, or when the vehicle body moves down and the piston 8 moves to the compression side, the damping coefficient C _{i is controlled} to the vehicle body vertical velocity. By controlling to an optimum damping coefficient according to X _2FL ′ to X _2RR ′, it is possible to secure a good ride comfort.

In addition, even when the vehicle is traveling on a rough road, the above-mentioned step
As when passing, the vehicle body rises and the piston 8 moves to the compression side.
Move or the vehicle body descends and the piston 8 moves to the extension side.
Coefficient C when the vibration direction is_iIs the minimum damping coefficient C
_aMINAnd C_nMINControl, and conversely, the body rises and the piston
8 moves to the extension side or the vehicle body descends and the piston 8
Damping coefficient C in the vibration damping direction moving to the compression side_iOn
Lower velocity X_2FL'~ X _2RR′ For optimal damping coefficient
By controlling, a good ride comfort can be ensured.

In this skyhook approximate control state,
Vehicle vertical speed X calculated in step S2 _2FL'~ X_2RR'But
Set value X_2S′, The damping coefficient C_FL~ C_RR
Characteristic curve L of the control map of FIG.₁Represented by
The gain is set to be greater than "1".
Therefore, as shown by a dotted line in FIG.
_2i'Is slow and the amplitude is small, the calculated attenuation coefficient
C_FL~ C_RRHowever, as shown by the dotted line in FIG.
It is a large value, exerts a good vibration damping effect, and
Ensuring that the body gives a fluffy discomfort
Can be avoided.

On the other hand, the vehicle vertical speed X_2i'Is the set value X_2S′
In the above region, a constant gain of approximately “1” is obtained.
The damping coefficient C_iIs the vehicle vertical speed X_2i′
As shown in FIG.
U, body vertical speed X_2i′ Is fast and the amplitude is large
Is the vehicle vertical speed X as shown by the solid line in FIG.
_2i'Corresponding to the damping coefficient C_iIs set,
A vibration damping effect can be exhibited.

By the way, as in the conventional example,
Body vertical speed X_2i'Is the set value X _2i′ And above
Control gain is set to a constant value of about "1"
In this case, as shown by a dotted line in FIG.
Degree X_2i′ Is slow and the amplitude is small,
Decay coefficient C_iAlso, as shown by a dashed line in FIG.
Body vertical speed X_2i′,
Such vehicle body vertical speed X_2i′ Is in the slow region
Being smaller and giving the crew a fluffy discomfort
become.

[0040] In the above embodiment, although the vehicle body vertical velocity X _2i 'small region has been described a case where setting the characteristic curve L ₁ to parabolic nonlinear, it is not limited thereto, the characteristic curve the L ₁ may be as to a polygonal line approximation, further not limited to the case of calculating by referring to the map the damping coefficient C _i, may be calculated by the calculation.

Next, a second embodiment of the present invention will be described with reference to FIGS. This second embodiment is obtained so as to change in accordance 'the control gain when calculating the damping coefficient C _i on the basis of the vehicle body vertical velocity X _2i' body vertical velocity X _2i on. In the second embodiment, the processing shown in FIG. 13 is performed by the arithmetic processing unit 56c of the microcomputer 56 in place of the processing of FIG. It has the same configuration as the example.

That is, in the processing of FIG. 13, first, the vertical acceleration detection values X _2FL ″ to X _2RR ″ are read in step S11, and then the _{process proceeds} to step S12, where the vertical acceleration detection values X _2FL ″ to by integrating the X _2RR "calculates the vehicle body vertical velocity X _2FL '~X _2RR', then the process proceeds to step S13a, on the basis of the vehicle body vertical velocity X _{2F L} '~X _2RR', control shown in FIG. 14 The control gain α is calculated with reference to the gain calculation map, and is updated and stored in the control gain storage area formed in the storage device 56d. Here, as shown in FIG. 14, the control gain calculation map has a maximum value α _MAX of “1” or more when the vehicle body vertical speed X _2i ′ is zero, and increases as the vehicle body vertical speed X _2i ′ increases. When the value decreases inversely and reaches the set value X _2S ′, the control gain α becomes “1”, and thereafter the control gain α maintains “1” regardless of the increase in the vehicle body vertical speed X _2i ′.

Next, the process proceeds to step S13b, where the vehicle
Body vertical speed X_2i'And the control stored in the storage device 56.
The following equation (1) is used to calculate the attenuation
Number C _iIs calculated. C_i= ΑX_2i'(1) Thereafter, steps S4 to S1 similar to those in the first embodiment described above.
0 and the damping coefficient C_iTarget step angle θ according to
_TiIs calculated, and the step control amount S corresponding to this is calculated._iIs calculated
To drive the step motors 41FL to 41RR.

[0044] According to the second embodiment, the control gain α calculating a damping coefficient C _i, as shown in FIG. 14, in the vehicle body vertical velocity X _2i 'set value X _2S' smaller area,
It is greater than "1" and decreases with an increase in the vehicle body vertical speed _X2i ', and is set to "1" above the set value _X2S ', so that the vehicle body vertical speed X _2i ′
When the vehicle speed is low and the amplitude is small, a good vibration damping effect is exerted, and it is possible to reliably avoid giving the occupant an uncomfortable feeling that the vehicle body is fluffy.

In each of the above embodiments, the case where the valve element 31 for controlling the damping force is formed in a rotary type is described. However, the present invention is not limited to this. Different flow paths may be formed on the extension side, and in this case, the step motors 41FL to 41FL
A pinion may be connected to the rotating shaft 41a of the 41RR, and a rack that meshes with the pinion may be attached to the connecting rod 42 or an electromagnetic solenoid may be used to control the sliding position of the valve element 31.

Further, in each of the above embodiments, the case where the change in the posture of the vehicle body due to the vibration input from the road surface is suppressed has been described. However, the present invention is not limited to this, and the running state such as the turning state and the braking state of the vehicle is detected. Alternatively, control for suppressing a change in the posture of the vehicle body due to this may be performed together. further,
In the above embodiments, the description has been given of the case of calculating the damping coefficient C _i on the basis of the vehicle body vertical acceleration X _2i ',
The invention is not limited thereto, and calculates the damping coefficient C _i by performing the calculation of the following expression (2) based on 'the relative speed X _Di between the sprung and unsprung' body vertical velocity X _2i and Skyhook control may be performed.

C _i = α · X _2i ′ / X _Di (2) Further, in each of the above embodiments, the controller 4
Is described using a microcomputer 56, but the present invention is not limited to this. The controller may be configured by combining electronic circuits such as an integrator, a function generator, an arithmetic circuit, and a comparator. .

In each of the above-described embodiments, the vertical acceleration sensors 51FL-51FL are mounted on the wheels 1FL-1RR of the vehicle body 2.
Although the case where the RR is provided has been described, any one of the vertical acceleration sensors may be omitted, and the vertical acceleration at the omitted position may be estimated from the values of the other vertical acceleration sensors. Furthermore, in the above embodiment, the case where the step motors 41FL to 41RR are controlled by open loop has been described. However, the present invention is not limited to this, and the rotation angle of the step motors is detected by an encoder or the like, and this is fed back to perform closed loop control. You may make it.

[0049]

As described above, according to the suspension control apparatus of the first aspect, the damping force is changed according to the input control signal interposed between the vehicle body side member and the wheel side member. , A vertical acceleration detecting means for detecting a sprung vertical acceleration at the position of the suspension device, and a vehicle body based on at least a sprung vertical speed obtained by integrating at least a sprung vertical acceleration detection value of the vertical acceleration detecting means. of the suspension control apparatus and control means for posture change suppressing the control signal formed by the output, the control means, on the spring vertical speed
The gain for calculating the damping coefficient based on the degree is set to a predetermined value in a region where the sprung vertical speed is equal to or more than a set value, and the sprung vertical speed is set to a set value in a region where the sprung vertical speed is smaller than the set value. Since the configuration is provided with the gain setting means for setting the value so as to increase as the value decreases, a good vibration damping effect can be exhibited over a wide range from a region where the vehicle body vertical speed is small to a region where the vehicle vertical speed is large. As a result, it is possible to surely prevent the occupant from giving an uncomfortable feeling that the vehicle body is fluffy due to insufficient vibration damping effect in a region where the sprung vertical speed is small.

According to the suspension control device of the second aspect, the gain setting means calculates the damping coefficient .
The sprung vertical speed is set to a predetermined value when the sprung vertical speed is equal to or higher than a set value, and in a region where the sprung vertical speed is smaller than the set value, linearly increases as the sprung vertical speed decreases from the set value. since there is a to that configuration settings in the gain, in inverse proportion to the reduction of the set value of the vertical sprung mass velocity can be increased, better by increasing the damping coefficient on the lower spring vertical velocity The effect that a great damping effect can be exhibited is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a basic configuration of the present invention.

FIG. 2 is a schematic configuration diagram showing one embodiment of the present invention.

FIG. 3 is a partially sectional front view showing an example of a variable damping force shock absorber.

FIG. 4 is an enlarged sectional view showing a damping force adjusting mechanism in a maximum damping force state when the vehicle body is lifted.

FIGS. 5A and 5B are enlarged sectional views showing a damping force adjusting mechanism in an intermediate damping force state when the vehicle body is lifted, wherein FIG. 5A shows a hydraulic oil path on the extension side and FIG.

FIGS. 6A and 6B are enlarged cross-sectional views illustrating a damping force adjustment mechanism when the vehicle body does not fluctuate. FIG.

FIGS. 7A and 7B are enlarged cross-sectional views illustrating a damping force adjusting mechanism in a state of a maximum damping force when the vehicle body descends, wherein FIG. 7A illustrates a hydraulic oil path on the extension side and FIG.

FIG. 8 is an explanatory diagram showing a damping force characteristic with respect to a step angle of a variable damping force shock absorber.

FIG. 9 is a block diagram illustrating an example of a controller.

FIG. 10 is a flowchart illustrating an example of a processing procedure of a controller.

FIG. 11 is an explanatory diagram showing a control map showing a relationship between a vehicle body vertical speed and a damping coefficient.

FIG. 12 is a time chart for explaining the operation of the first embodiment;

FIG. 13 is a flowchart illustrating an example of a processing procedure of a controller according to the second embodiment of the present invention.

FIG. 14 is an explanatory diagram showing a control gain calculation map showing a relationship between a vehicle vertical speed and a control gain.

[Explanation of symbols]

 1FL-1RR Wheel 2 Body 3FL-3RR Variable damping force variable shock absorber 4 Controller 8 Piston 11 Lower half 12 Upper half 13 Extension oil flow path 14 Compression oil flow path 18 Extension disc valve 19 Compression disk valve 28 Compression disk valve 31 valve element 32 through hole 33 communication groove 34 long hole 35 piston rod T1 to T3 extension side flow path C1 to C4 pressure side flow path 41FL to 41RR step motor 51FL to 51RR vertical acceleration sensor 56 microcomputer 59FL to 59RR motor drive circuit

Claims (2)

(57) [Claims] 1. A suspension device capable of changing a damping force according to an input control signal interposed between a vehicle body-side member and a wheel-side member, and a sprung vertical acceleration at the position of the suspension device. Vertical acceleration detecting means for detecting, and control means for forming and outputting the control signal for suppressing a change in posture of the vehicle body based on a sprung vertical velocity obtained by integrating at least a sprung vertical acceleration detection value of the vertical acceleration detecting means; In the suspension control device, the control means sets a gain for calculating a damping coefficient based on the sprung vertical speed to a predetermined value in a region where the sprung vertical speed is equal to or more than a set value. And a gain setting means for setting the sprung vertical speed to increase as the sprung vertical speed decreases below the set value in a region where the sprung vertical speed is smaller than the set value. Suspension control system, characterized in that. 2. The gain setting means calculates an attenuation coefficient .
The gain for, when sprung mass vertical velocity is equal to or more than a set value is set to a predetermined value, the region sprung mass vertical velocity is smaller than the set value increases linearly with vertical velocity on the spring is reduced below the set value The suspension device according to claim 1, wherein the suspension device is set as follows.