JP2000211337A - Control device of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase stability and controllability when steering a vehicle. SOLUTION: It is judged whether or not the absolute value of steering angular velocity is equal to or greater than a reference value, that is, whether or not the magnitude of steering velocity is equal to or more than the reference value, and it is judged whether or not the absolute value of vertical acceleration of unsprung resonance vibration is equal to or greater than a reference value. In the case where the magnitude of steering velocity is large and the unsprung resonance level is high, the damping coefficient of a shock absorber 26i is set high, and the damping coefficient on the extending side of an active engine mount 32 is set to a value higher than the standard value. In the case where the magnitude of steering velocity is large and the unsprung vibration level is high, the damping coefficient of the shock absorber 26i is set to a slightly lower value. In both cases, the damping coefficient on the extending side of the active engine mount 32 is set high, and an engine is lowered relatively to a vehicle body by vertical vibration, whereby the roll amount of the body is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a vehicle, and more particularly to a control device for improving the steering stability of a vehicle.

[0002]

2. Description of the Related Art As one of control devices for improving the ride comfort of a vehicle, for example, as described in Japanese Patent Application Laid-Open No. 8-175193, an active engine mount is adopted in addition to an active suspension.
Control devices configured to reduce the unsprung resonance frequency component of the vehicle and improve the behavior of the vehicle when the wheels pass over uneven road surfaces are already known.

According to the control device described in the above publication,
The active engine mount is controlled when the wheel passes over unevenness on the road surface, and the unsprung resonance frequency component of the vehicle is reduced, so that the ride comfort of the vehicle is improved as compared to a case where the active engine mount is not controlled. Can be improved.

[0004]

However, the above-mentioned publication discloses improving the riding comfort of the vehicle by controlling the active engine mount in a situation where the unsprung resonance frequency component of the vehicle is large. However, there is no description or suggestion about improving the steering stability of the vehicle, particularly the steering stability of the vehicle during steering, and there is room for improvement in this regard.

The present invention has been made in view of the above-described problems in a conventional control device configured to improve the ride comfort of a vehicle by controlling an active engine mount. The main challenge is to activate the suspension characteristics changing means during steering,
An object of the present invention is to improve the steering stability during steering of a vehicle by appropriately controlling the relative position of a heavy object mounted on the vehicle body in the vertical direction with respect to the vehicle body.

[0006]

SUMMARY OF THE INVENTION According to the present invention, there is provided a suspension characteristic changing means for changing suspension characteristics between a hard side and a soft side, and a vehicle mounted on a vehicle body. Means for vertically moving the heavy object relative to the vehicle body, and steering state detecting means. When the steering state is in a predetermined state, the suspension characteristic changing means is operated and the heavy object is actuated. This is achieved by a control device for a vehicle, wherein the heavy object is lowered by vertical movement means.

According to the first aspect of the present invention, when the steering state is in the predetermined state, the suspension characteristic changing means is operated, and the heavy object is lowered by the heavy object vertical moving means, whereby the center of gravity of the whole vehicle is obtained. Is reduced and the roll center of the vehicle is raised, so that the roll amount of the vehicle body is reliably reduced.

According to the present invention, in order to effectively achieve the above-mentioned main object, in the above-described configuration of the first aspect, the heavy object is configured to be an engine.
Configuration).

According to the second aspect of the present invention, the heavy object is an engine, and the weight of the engine is generally very large. Therefore, the center of gravity of the vehicle as a whole is reliably reduced without requiring any special heavy object other than the engine. Is done.

According to the present invention, in order to effectively achieve the above-mentioned main object, the suspension characteristic changing means may change the damping characteristic of the suspension. (Configuration of Claim 3).

According to the third aspect of the present invention, when the steering state is in the predetermined state, the damping characteristic of the suspension is changed, so that the vibration of the relative displacement between the sprung and the unsprung when the vehicle turns is determined. The damping property can be changed.

Further, according to the present invention, in order to effectively achieve the above-mentioned main object, in the above-mentioned structure of the first to third aspects, the predetermined state is such that the magnitude of the steering speed is equal to or larger than a reference value. It is configured to be in a state (the configuration of claim 4).

According to the fourth aspect of the present invention, the predetermined state is a state in which the magnitude of the steering speed is equal to or higher than the reference value. Is activated, and the center of gravity of the entire vehicle is reliably lowered.

Further, according to the present invention, in order to effectively achieve the above-mentioned main object, in the above-mentioned constitutions of claims 1 to 4, the suspension characteristic changing means includes means for detecting resonance of the vehicle. When the steering state is the predetermined state and the resonance level of the vehicle is large, the suspension characteristic is changed to the hard side (the configuration of claim 5).

According to the fifth aspect of the present invention, when the steering state is a predetermined state and the resonance level of the vehicle is large, the suspension characteristic is changed to the hard side, so that the suspension characteristic is caused by the resonance during turning of the vehicle. The so-called bull-blur vibration of the running vehicle is reliably reduced.

Further, according to the present invention, in order to effectively achieve the above-mentioned main object, in the above-mentioned constitutions of claims 1 to 4, the suspension characteristic changing means includes means for detecting unsprung vibration. When the steering state is the predetermined state and the unsprung vibration frequency is in a predetermined frequency range, the suspension characteristic is changed to a soft side (the configuration of claim 6).

According to the configuration of the sixth aspect, when the steering state is a predetermined state and the unsprung vibration frequency is in a predetermined frequency range, the suspension characteristic is changed to the soft side, so that the predetermined frequency By appropriately setting the area, so-called rugged vibration during turning of the vehicle is reliably reduced.

[0018]

According to a preferred aspect of the present invention, in the configuration of the first aspect, the heavy object vertically moving means elastically supports the heavy object and has at least an extension side damping coefficient. Can be changed, and the damping coefficient on the extension side is increased when the steering state is in a predetermined state (preferred mode 1).

According to another preferred embodiment of the present invention, in the configuration of the above-mentioned preferred embodiment 1, the heavy object vertical movement means includes a piezoelectric element, and the heavy object is moved in accordance with a voltage applied to the piezoelectric element. The vibration of the vehicle body is actively damped by vibrating vertically (preferred embodiment 2).

According to another preferred embodiment of the present invention, in the configuration of the above-mentioned preferred embodiment 1, the heavy object vertically moving means is configured such that a spring constant can be changed (preferred embodiment 3).

According to another preferred embodiment of the present invention, in the configuration of the second aspect, the heavy object vertical moving means elastically supports the engine and can change at least the extension side damping coefficient. It is configured to be a configured active engine mount (preferred embodiment 4).

According to another preferred embodiment of the present invention, in the configuration of the third aspect, the suspension characteristic changing means is configured to be a variable damping force type shock absorber (preferred embodiment 5).

According to another preferred embodiment of the present invention, in the structure of the preferred embodiment 5, the shock absorber is configured such that a spring constant of an upper support connecting an upper end thereof and a vehicle body can be changed. (Preferred embodiment 6).

According to another preferred aspect of the present invention, in the configuration of the fourth aspect, the magnitude of the steering speed is configured to be an absolute value of the steering angular velocity (preferred aspect 7).

According to another preferred aspect of the present invention, in the configuration of the fifth aspect, the means for detecting the resonance of the vehicle is such that the frequency of the unsprung vibration is within the range of the resonance frequency of the vehicle. It is configured to detect the resonance of the vehicle depending on whether or not (preferred mode 8).

According to another preferred aspect of the present invention, in the configuration of the sixth aspect, the predetermined frequency range is configured to be a frequency range that degrades ride comfort of the vehicle (preferred mode). 9).

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a schematic structural view showing one embodiment of a vehicle control device according to the present invention applied to a passenger car, and FIG.
FIG. 2 is a block diagram of the embodiment shown in FIG. 1.

In FIG. 1, reference numeral 10 denotes a vehicle body, reference numerals 12 and 14 denote front and rear wheels, respectively, and reference numerals 16 and 18 denote suspensions of the front wheels 12 and the rear wheels 14, respectively. In FIG. 1, the front wheel 12 is shown as comprising a spring 20f and a mass Mwf, and the rear wheel 14 is shown as comprising a spring 22r and a mass Mwr.

As shown in FIG. 1, the suspension 16 of the front wheel 12 comprises a suspension spring 24f arranged in parallel with each other and a variable damping force type shock absorber 26f. The shock absorber 26f has a damping coefficient Csf. And the spring constant Ks of the upper support 28f
f can be variably controlled within a predetermined range.

Similarly, the suspension 18 of the rear wheel 14 includes suspension springs 24 arranged in parallel with each other.
r and a variable damping force type shock absorber 26r. The shock absorber 26r can variably control the damping coefficient Csr and the spring constant Ksr of the upper support 28r within a predetermined range.

An engine 30 as a heavy object having a mass Me is mounted on a front portion of the vehicle body 10. The engine 30 is supported by a vehicle body via an active engine mount 32. In FIG. 1, only one active engine mount 32 is schematically shown, but the active engine mount 32 is
Are provided corresponding to at least four corners.

Active engine mounts are well known in the art and will not be described in detail, but in particular, the active engine mount 32 has a built-in piezoelectric element and responds to the voltage applied to the piezoelectric element. The engine 30 can be moved up and down relatively to the vehicle body 10 to actively control the vibration of the vehicle body (active vibration suppression mode), and the path for connecting and connecting the main liquid chamber and the sub liquid chamber can be changed. By controlling the aperture, the extension side damping coefficient Cee can be variably controlled as shown in FIG.
Further, the spring constant Ke can be variably controlled by controlling the communication and cutoff between the main liquid chamber and the gas chamber.

As shown in FIG. 1, the front wheels 12 and the rear wheels 14 have acceleration sensors 34f and 34r for detecting the vertical accelerations Gwf and Gwr of the corresponding wheels (unsprung), respectively.
Is provided. Further, the vehicle body 10 is provided with acceleration sensors 36f and 36r for detecting vertical accelerations Gbf and Gbr of the vehicle body at the center of the vehicle at positions substantially corresponding to the front wheels 12 and the rear wheels 14, respectively. Further, the steering device 38 includes a steering angle sensor 4 for detecting a steering angle θ.
0 is provided.

As shown in FIG. 2, the acceleration sensor 3
Signals indicating the vertical accelerations Gbf and Gbr of the vehicle body detected by 6f and 36r are band-pass filters 42f, 42r and A having a pass band of, for example, 0.5 to 2 Hz.
The electric control device 46 outputs signals indicating the vertical accelerations G1f and G1r of the swing vibration of the vehicle body via the / D converters 44f and 44r.
A signal indicating the steering angle θ detected by the steering angle sensor 40 is also supplied to the electric control device 46.

The left and right front wheel acceleration sensors 34fr, 34
The vertical acceleration Gwf of the front left and right wheels respectively detected by fl
r, the signal indicating Gwfl and the acceleration sensor 34r for the left and right rear wheels
The signals indicating the vertical accelerations Gwrr and Gwrl of the left and right rear wheels detected by r and 34rl respectively are, for example, 4 to 8 respectively.
Bandpass filter 48i (i = f
r, fl, rr, rl) and an A / D converter 50i, and is supplied to the electric control device 46 as a signal indicating the vertical acceleration G2i of the rugged vibration of the vehicle.
Bandpass filter 52i and A / D with z as passband
The signal is supplied to the electric controller 46 via the converter 54i as a signal indicating the vertical acceleration G3i of the unsprung resonance vibration (bulble vibration of the vehicle).

The electric control unit 46 controls the steering angle θ as described later.
, The steering angular velocity θd, the vertical accelerations G1f and G1r of the tilting vibration of the vehicle, the vertical acceleration G2i of the vehicle's rattling vibration, and the vertical acceleration G of the resonance vibration under the spring.
3i, shock absorber 26i, upper support 28i and active engine mount 3 if necessary.
2 to thereby improve the riding comfort and steering stability of the vehicle.

Although not shown in detail in FIG. 2, the electric control unit 46 includes a microcomputer and a drive circuit. The microcomputer includes, for example, a central processing unit (CPU), a read only memory (ROM), , A random access memory (RAM), and an input / output port device, which may be connected to each other by a bidirectional common bus.

Next, a control routine of the shock absorber 26i, the upper support 28i and the active engine mount 32 in the illustrated embodiment will be described with reference to the flowcharts shown in FIGS. FIG. 3
The control according to the flowchart shown in FIG. 4 is started by closing an ignition switch (not shown), and is repeatedly executed at predetermined time intervals. Steps 30 to 90 and steps 100 to 180 are executed individually for the left front wheel and the right front wheel.

First, in step 10, signals indicating the vertical accelerations G1f and G1r of the tilting vibration of the vehicle body are read, and in step 20, for example, the steering angular velocity θd is calculated as a time differential value of the steering angle θ. As well as
It is determined whether or not the absolute value of the steering angular velocity θd is equal to or greater than the reference value θdo (positive constant), that is, whether or not the magnitude of the steering speed is equal to or greater than the reference value, and a negative determination is performed. If so, the process proceeds to step 100, and if a positive determination is made, the process proceeds to step 30.

In step 30, the absolute value of the vertical acceleration G3f of the unsprung resonance vibration is set to a reference value G3fo (positive constant).
It is determined whether or not this is the case. If a negative determination is made, the process proceeds to step 50, and if an affirmative determination is made, the flag Ff is set to 1 in step 40. In step 50, it is determined whether or not the flag Ff is 1. When the affirmative determination is made, the process directly proceeds to step 190, and when the negative determination is made, the process proceeds to step 60.

In the illustrated embodiment, the reference value G3f
Although o is a positive constant, this reference value may be variably set by, for example, fuzzy control according to the level of rugged vibration of the vehicle and the level of tilt vibration of the vehicle body.

In step 60, the absolute value of the vertical acceleration G2f of the rugged vibration of the vehicle is set to a reference value G2fo (positive constant).
It is determined whether or not the above is the case. When the affirmative determination is made, the flag Ff is set to 2 in step 70, and when the negative determination is made, the process proceeds to step 80. In step 80, it is determined whether or not the flag Ff is 2. When the affirmative determination is made, the process directly proceeds to step 190. When the negative determination is made, the flag Ff is set to 3 in step 90. Is set to

In step 100, it is determined whether or not the absolute value of the vertical acceleration G1f of the tilting vibration of the vehicle body is greater than or equal to a reference value G1fo (positive constant). If the flag Ff is set to 4 in step (1) and a negative determination is made, step 12
Go to 0. In step 120, it is determined whether or not the flag Ff is 4; if an affirmative determination is made, the process proceeds directly to step 190; if a negative determination is made, the process proceeds to step 130.

In step 130, it is determined whether or not the absolute value of the vertical acceleration G2f of the rugged vibration of the vehicle is equal to or larger than the reference value G2fo. If an affirmative determination is made, the flag Ff is determined in step 140. Is set to 5,
When a negative determination is made, the routine proceeds to step 150. In step 150, it is determined whether or not the flag Ff is 5; if an affirmative determination is made, the process proceeds directly to step 190; if a negative determination is made, the process proceeds to step 160.

In the illustrated embodiment, step 3
Although the reference values for the discrimination in 0 and 160 and in steps 60 and 130 are the same, the reference values for these discriminations may be different values.

In step 160, it is determined whether or not the absolute value of the vertical acceleration G3f of the unsprung resonance vibration is equal to or more than the reference value G3fo. When Ff is set to 6 and a negative determination is made, the flag Ff is reset to 0 in step 180.

When the flag Ff is set to 1 and 6 in steps 40 and 170, respectively, so as not to frequently switch between 0 and another value, as shown in FIG. The set value is maintained for a predetermined period of time from the time when the affirmative determination is made in steps 30 and 160.
When it is set to 5, as shown in FIG. 7, the set value is maintained for a predetermined time from the time when the affirmative determination is made in steps 60 and 130.
When set to 3 and 4 at 0 and 110, respectively, as shown in FIG.
In the above, the set value is maintained for a predetermined time from the time when the positive determination is made.

In step 190, according to the flag Ff, the shock absorbers 26fr and 26fl, the upper supports 28fr and 28fl, the active engine mount 3
2 is controlled. In this case, when the flag Ff is 0, the shock absorbers 26fr and 26fl, the upper supports 28fr and 28fl, and the active engine mount 32 are not controlled and are each maintained in the standard state (non-control state).

When the flag Ff is 1, the vehicle is in a transient turning state and the unsprung resonance level is high, so that the damping coefficients Csfr and Csfl of the shock absorbers 26fr and 26fl are higher than the standard values. Is set to
Spring constant Ksfr, Ksfl of upper support 28fr, 28fl
Is set to a value higher than the standard value, the active engine mount 32 is controlled in the active vibration suppression mode, and the extension-side damping coefficient Cee is set to a value higher than the standard value.

When the flag Ff is 2, the vehicle is in a transient turning state and the level of the rugged vibration of the vehicle is high, so that the shock absorbers 26fr, 2fr
The damping coefficients Csfr and Csfl of 6 fl are set to values slightly lower than the standard values, and the spring constants Ksfr and Ksfl of the upper supports 28 fr and 28 fl are set to values slightly lower than the standard values. Damping coefficient Cee
Is set to a high value.

When the flag Ff is 3, the vehicle is in a transient turning state and both the level of unsprung resonance vibration and the level of rugged vibration of the vehicle are low. Therefore, the damping of the shock absorbers 26fr and 26fl is performed. Coefficient C
sfr and Csfl are set to values higher than the standard values, the spring constants Ksfr and Ksfl of the upper supports 28fr and 28fl are set to values higher than the standard values, and the spring constant Ke of the active engine mount 32 is higher than the standard values. And the damping coefficient Cee on the extension side is set to a value higher than the standard value.

When the flag Ff is 4, the vehicle is in a state in which the level of the tilting vibration of the vehicle body is high, so that the damping coefficients Csfr and Cs of the shock absorbers 26fr and 26fl are set.
fl is set to a value higher than the standard value and upper support 2
The spring constants Ksfr and Ksfl of 8fr and 28fl are set to values lower than the standard values, and the active engine mount 32 is maintained in an uncontrolled state.

When the flag Ff is 5, the damping coefficients Csfr and Csfl of the shock absorbers 26fr and 26fl are set to lower values than the standard value because the vehicle is in a state of high rugged vibration, and the upper support 28fr and
The spring constants Ksfr and Ksfl of 28 fl are set to values lower than the standard values, and the active engine mount 32 is maintained in an uncontrolled state.

Further, when the flag Ff is 6, the vehicle has a high level of unsprung resonance vibration, and the damping coefficients Csfr and Cs of the shock absorbers 26fr and 26fl are high.
fl is set to a moderately high value, upper support 28fr,
The spring constants Ksfr and Ksfl of 28 fl are set to values higher than the standard value, the active engine mount 32 is controlled in the active vibration suppression mode, or the spring constant Ke is set to a value higher than the standard value.

When the control of the active engine mount 32 conflicts between the control of the front right wheel and the control of the front left wheel, the control of the front right wheel is given priority, and the control of the active engine mount 32 by the control of the front right wheel. In the non-control state, the active engine mount 32 is controlled by controlling the left front wheel.

In step 200, the same steps as steps 20 to 190 described above are executed for the left and right rear wheels. In particular, in the step corresponding to step 190, a shock is applied according to the flag Fr corresponding to the flag Ff. The absorbers 26rr and 26rl, the upper supports 28rr and 28rl, and the active engine mount 32 are controlled.

The steps corresponding to steps 30 to 90 and steps 100 to 180 are individually executed for the left rear wheel and the right rear wheel. When the control of the active engine mount 32 conflicts between the control of the front wheels and the control of the rear wheels, the control of the front wheels has priority and the active engine mount 32 by the control of the front wheels.
Is not controlled, the active engine mount 32 is controlled by controlling the rear wheels.

As is apparent from the above description, in the illustrated embodiment, for example, when the vehicle travels substantially straight on a flat road, the absolute value of the steering angular velocity θd, the tilt of the vehicle body Since the absolute value of the vertical acceleration G1 of the vibration, the absolute value of the vertical acceleration G2 of the rugged vibration of the vehicle, and the absolute value of the vertical acceleration G3 of the unsprung resonance vibration are all smaller than the corresponding reference values, the flags Ff and Fr Becomes 0, and therefore, the shock absorber 26i, the upper support 28i, and the active engine mount 32 are not controlled, and are each maintained in the standard state (non-control state).

When the vehicle is in a transient turning state and the absolute value of the unsprung vertical acceleration G3 is greater than or equal to the reference value and the unsprung resonance level is high, as in the case where the vehicle accelerates at the end of turning, the flag Ff Fr becomes 1, the damping coefficient Csi of the shock absorber 26i is set to a value higher than the standard value, the spring constant Ksi of the upper support 28i is set to a value higher than the standard value, and the active engine mount 32 is activated. The control is performed in the mode, and the extension-side damping coefficient Cee is set to a value higher than the standard value.

Therefore, in this case, the shock absorber 2
Active engine mount 3 with increased 6i damping force
2 is controlled in the active vibration suppression mode,
The rolling vibration of the vehicle is reduced, the roll of the vehicle body is suppressed, and the damping force on the extension side of the active engine mount 32 is relatively increased. It is relatively lowered, and the center of gravity of the vehicle as a whole is lowered, which also suppresses the roll of the vehicle body, thereby improving the ride comfort and steering stability of the vehicle when the vehicle accelerates at the end of turning. Be improved.

When the vehicle is in a transient turning state and the absolute value of the vertical acceleration G2f of the rugged vibration of the vehicle is equal to or larger than the reference value, such as at the beginning of a turn or at the end of the turn when the vehicle turns on a bad road, a flag is set. Ff and Fr become 2, the damping coefficient Csi of the shock absorber 26i is set to a value slightly lower than the standard value, the spring constant Ksi of the upper support 28i is set to a value slightly lower than the standard value, and the active engine mount 32 is set. Is not controlled in the active vibration suppression mode, and the extension side damping coefficient Cee is set to a high value.

Therefore, in this case, the shock absorber 2
By appropriately setting the damping force and its phase of 6i, the rugged vibration transmitted from the unsprung portion to the sprung portion is reduced, and the damping force on the extension side of the active engine mount 32 is relatively increased. When the engine 30 is lowered relative to the vehicle body 10 due to the vertical vibration thereof, and the center of gravity of the vehicle as a whole is lowered, the roll of the vehicle body is suppressed. Ride comfort and steering stability of the vehicle at the beginning of a turn, at the end of a turn, and the like are improved.

Further, when the vehicle is turning on a good road, such as at the beginning of a turn or at the end of a turn, the vehicle is in a transient turning state, but both the level of unsprung resonance vibration and the level of rugged vibration of the vehicle are low. At some point, the flags Ff and Fr become 3, the damping coefficient Csi of the shock absorber 26i is set to a value higher than the standard value, and the upper support 28i
Is set to a value higher than the standard value, the spring constant Ke of the active engine mount 32 is set to a value higher than the standard value, and the extension side damping coefficient Cee is set to a value higher than the standard value. Is done.

Therefore, in this case, the shock absorber 2
Active engine mount 3 with increased 6i damping force
By setting the spring constant of 2 high, the roll of the vehicle body is suppressed and the swing of the engine 30 is also suppressed,
In addition, since the extension-side damping force of the active engine mount 32 is relatively increased, the engine 30 is relatively lowered with respect to the vehicle body 10 due to its vertical vibration,
The center of gravity of the vehicle as a whole is reduced, which also suppresses the roll of the vehicle body, thereby improving the steering stability of the vehicle at the beginning of a turn or at the end of a turn when the vehicle turns on a good road. .

Also, when the vehicle is not in a transient turning state but is running on a undulating road surface and the level of the tilting vibration of the vehicle body is high, the flags Ff and Fr are set to 4 and the damping coefficient of the shock absorber 26i is set. Csi is set to a value higher than the standard value, the spring constant Ksi of the upper support 28i is set to a value lower than the standard value, and the active engine mount 32 is maintained in an uncontrolled state.

Therefore, in this case, the shock absorber 2
By increasing the damping force of 6i and appropriately setting the phase of the damping force, the tilt of the vehicle body is reduced, whereby the riding comfort and steering stability of the vehicle when the vehicle travels on a undulating road surface or the like. Is improved.

When the vehicle is not in a transient turning state but is traveling on a rough road, the flag Ff and Fr are set to 5 when the vehicle is in a situation where the level of rugged vibration is high.
The damping coefficient Csi of the shock absorber 26i is set to a value lower than the standard value, the spring constant Ksi of the upper support 28i is set to a value lower than the standard value, and the active engine mount 32 is maintained in an uncontrolled state.

Accordingly, in this case, the shock absorber 2
By reducing the damping force of 6i and appropriately setting the phase of the damping force, the rugged vibration transmitted from unsprung to sprung is reduced. Ride comfort is improved.

Further, as in the case where the vehicle accelerates from a low speed,
When the vehicle has a high level of unsprung resonance vibration, the flags Ff and Fr are set to 6, the damping coefficient Csi of the shock absorber 26i is set to a moderately high value, and the spring constant Ksi of the upper support 28i is set to a standard value. The active engine mount 32 is set to a value higher than the standard value and the spring constant Ke is set to a value higher than the standard value.

Therefore, in this case, the shock absorber 2
6i is controlled to a moderately high value and the active engine mount 32 is controlled in the active vibration suppression mode or the spring constant Ke is set to a value higher than the standard value, so that the unsprung resonance vibration is reduced. (Vulnerable vibration of the vehicle) is reduced, thereby improving the riding comfort of the vehicle when the vehicle accelerates at a low speed.

Thus, according to the illustrated embodiment, the damping coefficient Csi of the shock absorber 26i, the spring constant Ksi of the upper support 28i, and the active engine mount 32 can be appropriately controlled according to the running condition of the vehicle. Irrespective of the running condition of the vehicle, the riding comfort and the steering stability can be reliably improved.

In particular, according to the illustrated embodiment, the damping coefficient Kee on the extension side of the active engine mount 32 is set higher than the standard value during the transient turning of the vehicle, so that the engine 30 gradually moves to the vehicle body 10 due to its vibration. On the other hand, since the engine 30 is relatively lowered, the engine 30 can be lowered without requiring energy for moving the engine 30.

Further, according to the illustrated embodiment, the spring constant Ksi of the upper support 28i and the spring constant Ke of the active engine mount 32 are also variably controlled as required, so that the ratio is constant when these spring constants are constant. As a result, the roll amount of the vehicle body can be effectively reduced, and the vibration of the vehicle body can be effectively suppressed.

In the above, the present invention has been described in detail with respect to a specific embodiment. However, the present invention is not limited to the above embodiment, and various other embodiments are included within the scope of the present invention. It will be clear to those skilled in the art that is possible.

For example, in the above-described embodiment, the active engine mount 32 has a damping coefficient Cee on its extension side.
However, the active engine mount 32 is also configured so that the contraction-side damping coefficient Cec can be variably controlled, and when the flags Ff and Fr are 1 or 2 or 3, The damping coefficient Cee is set to a value higher than the standard value, and the damping coefficient Cec on the contraction side is set to a value lower than the standard value, so that the engine 30 is more efficiently lowered during the transient turning of the vehicle. It may be configured as follows.

In the above-described embodiment, the means for detecting the resonance of the vehicle is an acceleration sensor for detecting the unsprung vertical acceleration.
Vertical acceleration Gbf on the spring detected by 6f and 36r
And Gbr, or may be detected based on a relative displacement between a sprung and unsprung state detected by a vehicle height sensor.

In the above-described embodiment, the active engine mount 32 is configured to be capable of active vibration suppression and variable control of the spring constant. Variable control may be omitted.

Further, in the above embodiment, the heavy object is the engine 30, but the heavy object may be any object such as a battery or a load as long as it can move up and down relative to the vehicle body 10. Although the means for moving the heavy object up and down is the active engine mount 32 having a variable damping coefficient, the heavy object such as the engine 30 may be moved up and down relative to the vehicle body by any means.

[0080]

As is apparent from the above description, according to the first aspect of the present invention, when the steering state is in the predetermined state, the suspension characteristic changing means is operated and the heavy object vertical moving means is operated. Heavy objects are lowered,
As a result, the center of gravity of the entire vehicle is lowered and the center of the roll of the vehicle is raised, so that the roll amount of the vehicle body can be reliably reduced, and the steering stability of the vehicle can be improved.

According to the second aspect of the present invention, the center of gravity of the entire vehicle can be reliably lowered without requiring any special heavy object other than the engine. The damping of the vibration of the relative displacement between the sprung and the unsprung at the time can be changed.
According to the configuration, the suspension characteristic changing means can be reliably operated during the transient turning of the vehicle in which the vehicle body is likely to roll, and the center of gravity of the entire vehicle can be reliably reduced.

According to the fifth aspect of the invention, the so-called bull bull vibration of the vehicle caused by the resonance during the turning of the vehicle can be reliably reduced, and the riding comfort of the vehicle can be improved. According to the configuration, by appropriately setting the predetermined frequency range, so-called rugged vibration during turning of the vehicle can be reliably reduced and the riding comfort of the vehicle can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a vehicle control device according to the present invention applied to a passenger car.

FIG. 2 is a block diagram of the embodiment.

FIG. 3 is a flowchart showing a part of a control routine of a shock absorber and the like in the embodiment.

FIG. 4 is a flowchart showing a remaining part of a control routine of a shock absorber and the like in the embodiment.

FIG. 5 is a graph showing a damping force characteristic of an active engine mount.

FIG. 6 is a graph showing a relationship between a change in an absolute value of a vertical acceleration G3f of unsprung resonance vibration and a flag Ff.

FIG. 7 is a graph showing a relationship between a change in an absolute value of a vertical acceleration G2f of rugged vibration of a vehicle and a flag Ff.

FIG. 8 is a graph showing a relationship between a change in an absolute value of a vertical acceleration G1f of a tilt vibration of a vehicle body and a flag Ff.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Body 12 ... Front wheel 14 ... Rear wheel 16, 18 ... Suspension 24f, 24r ... Suspension spring 26f, 26r ... Shock absorber 28f, 28r ... Upper support 30 ... Engine 32 ... Active engine mount 34f, 34r, 36f, 36r ... Acceleration Sensor 38: Steering device 40: Steering angle sensor

Continued on the front page (72) Inventor Kazunari Uemura 1-Toyota-cho, Toyota-shi, Aichi F-term in Toyota Motor Corporation (Reference) 3D001 AA03 BA01 CA01 EA08 EA34 EB00 EB26 EB32 ED02 3D035 CA19 CA36 CA44 3J069 AA50 EE35

Claims (6)

[Claims] 1. A suspension characteristic changing means for changing a suspension characteristic between a hard side and a soft side, a heavy object vertical moving means for vertically moving a heavy object mounted on a vehicle body relative to the vehicle body, and a steering state detecting means. A control device for a vehicle, wherein when the steering state is in a predetermined state, the suspension characteristic changing means is operated and the heavy object is lowered by the heavy object vertical movement means. 2. The vehicle control device according to claim 1, wherein the heavy object is an engine. 3. The vehicle control device according to claim 1, wherein said suspension characteristic changing means changes a damping characteristic of the suspension. 4. The vehicle control device according to claim 1, wherein the predetermined state is a state where the magnitude of the steering speed is equal to or higher than a reference value. 5. The suspension characteristic changing means includes means for detecting resonance of a vehicle, and when the steering state is the predetermined state and the resonance level of the vehicle is large, the suspension characteristic is changed to a hard side. The control device for a vehicle according to any one of claims 1 to 4, wherein: 6. The suspension characteristic changing means includes means for detecting unsprung vibration, wherein the suspension characteristic is changed when the steering state is the predetermined state and the unsprung vibration frequency is in a predetermined frequency range. The vehicle control device according to any one of claims 1 to 4, wherein the control is changed to a software side.