JPH0431186A - Control device for fluctuation of vehicle - Google Patents

Abstract

PURPOSE:To exactly prevent posture variation of a vehicle body in the vertical direction by providing movable wings capable of changing angle of incidence against running wind on a vehicle body, adjusting the angle of incidence of the movable wings according to vertical movement of the vehicle and the detected value of vehicle speed, and generating damping force against vertical vibration of the vehicle body on the movable wings. CONSTITUTION:A front and a rear movable wings 14f, 14r are respectively provided on the front side of a roof and the rear part of a vehicle body 10, and their angle of incidence can be changed with actuators 16f, 16r. A front wheel side and a rear wheel side vertical acceleration sensors 20f, 20r are respectively provided on the position of a front wheel 12f and a rear wheel 12r as a vertical movement detecting means, a vehicle speed sensor 21 is also provided, and their output signals are input to a controller 22. A command signal corresponding to the damping force against vertical movement is computed based on the detected signals of the vertical acceleration sensors 20f, 20r, the command signal is corrected so as to decrease the force as the detected value of sensor 21 increases, and the actuators 16f, 16r are controlled with the corrected command signal.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a vehicle body with a movable blade that changes the angle of attack with respect to relative wind, and adjusts the attack angle of the movable vane in accordance with the vertical vibration of the vehicle body. The present invention relates to a rocking control device that prevents rocking of a vehicle body.

[Prior Art] Conventionally, as a device for suppressing rocking occurring in a vehicle body, a suspension having a configuration as shown in FIG. 6, for example, is known.

This conventional suspension consists of a coil spring 2 having a spring constant and a shock absorber 3 having a damping constant C arranged in parallel between a vehicle body side member and a wheel side member of a vehicle body 1 (length: 1 m). The coil spring 2 supports the static load of the vehicle body, and the shock absorber 3 generates a damping force against the rocking of the vehicle body to absorb vibrations. It is a force proportional to the relative velocity of the stroke in question. As is well known, the transfer function of the suspension shown in FIG. 6 is based on the vertical displacement of the tire X3. Vehicle body vertical displacement X2. As a Laplace operator S, it is expressed as X ms” +Cs+.

However, in such conventional devices, the shock absorber 3 generates a damping force in proportion to the relative speed of the stroke between the vehicle body and the wheels. For example, the damping constant C of the shock absorber 3 is set to a large value in order to improve the ride comfort around the first section, which is the sprung mass resonance (vehicle body resonance) region, in response to posture changes such as roll and pitch of the vehicle body caused by such factors. Then, the riding comfort in the vicinity of 4 to 5 Hz on the higher frequency side deteriorates (see the dashed-dotted curve in Fig. 7).
If the damping constant C of the shock absorber 3 is set to a small value in order to improve the ride comfort around the 4th and 5th rows, the ride comfort around the 17th row will deteriorate (see the dotted line curve in Figure 7).
In order to overcome this situation, the present applicant proposed a proposal described in Japanese Patent Application No. 63-311615, in which a good riding comfort could not be maintained over the entire vibration frequency range of the vehicle body. This prior application includes a movable wing that is attached to the vehicle body and that changes the angle of attack relative to the relative wind that accompanies driving, an actuator that adjusts the angle of attack of this movable wing according to a command value, and a vehicle body bounce, roll, pitch, etc. and a means for calculating a command value corresponding to a force for attenuating or suppressing the rocking of the vehicle body based on the detection information of the rocking state detecting means. It is something.

[Problem to be solved by the invention]

However, in such a swing control device described in the earlier application, the command value for driving the movable blade, that is, the actuator, is calculated based only on signals representing the swing state such as vertical acceleration, and Because the above factors were not taken into consideration, even if the vehicle speed or airspeed changes, the angle of attack will always remain unchanged for these speeds.In particular, with regard to vibration damping in the vertical direction, the higher the speed, the lower the angle of attack will be. There was a situation in which a damping force greater than that of the previous model was generated on the movable blade, resulting in overdamping and halving the originally good ride comfort provided by the suspension.

This invention improves the unresolved problems in the prior application, and actively damps the vertical movement of the vehicle body, prevents over-damping in high-speed ranges, and improves the ride quality throughout driving. The problem we are trying to solve is to ensure a sense of comfort.

[Means to solve the problem]

In order to solve the above problems, the present invention includes: a movable blade that is attached to a vehicle body and can change the angle of attack with respect to relative wind as the vehicle travels; an actuator that adjusts the angle of attack of the movable blade in accordance with a command signal; Vertical motion detection means for outputting information corresponding to the vertical motion of the vehicle body; and command signal calculation means for calculating the command signal in accordance with a damping force for attenuating the vertical motion based on the detected value of the vertical motion detection means. The vehicle speed detecting means detects the vehicle speed, and the command signal correcting means corrects the calculated value of the command signal calculating means so that the damping force becomes weaker as the detected value of the vehicle speed detecting means increases.

(Operation) In the present invention, when the vehicle body vibrates in the vertical direction, this vertical movement is detected by the vertical movement detection means, and a command signal for damping the vertical vibration is calculated by the command signal calculation means.

This command signal is further corrected by the command signal correction means to a value such that the damping force becomes weaker as the speed increases, and this corrected command signal is supplied to the actuator.

For this reason, the angle of attack of the movable blade relative to the wind is adjusted to a value that corresponds to the vertical motion and offsets the increase in force caused by the vehicle speed, so the movable blade has a value that is adjusted to a value that offsets the increase in force caused by the vehicle speed. The truly necessary vertical force (downforce,
(lift force) is generated, and vehicle body vibrations are accurately damped.

In this way, the force that dampens the vertical movement of the car body actively acts, so the damping constant of the shock absorber of the suspension installed between the car body and wheels can be set to a small value. The vibration transmitted from the road surface to the vehicle body is also small.

Furthermore, as the speed increases, the damping force due to the movable blades is corrected to become weaker, thereby preventing over-damping at high speeds and maintaining good riding comfort.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 5 of the accompanying drawings.
This will be explained based on the diagram.

1 and 2, 10 is a vehicle body, 12f is a front wheel, and 12r is a rear wheel. The swing control device in this embodiment includes front and rear movable wings 14f and 14r located on the front side of the roof and the rear part of the vehicle body 10, respectively, and both rotary wings 14f.
, 14r, respectively, the actuators 16f, 1
6r and these actuators 16f, 16r to the vehicle body 10.
Support parts 18f and 18r that support the front wheel 12f
.

A front wheel side and rear wheel side vertical acceleration sensor 20f as a vertical movement detection means provided at the position of the rear wheel 12r.

20r, a vehicle speed sensor 21 as vehicle speed detection means, and a controller 22 that receives signals from these sensors 2Of, 20r and 2I and controls the actuators 16f and 16r.

Among these, the front and rear movable wings 14f and 14r have a substantially rectangular shape when viewed from the vertical direction of the vehicle, have rounded front edges when viewed from the lateral direction of the vehicle, and have a streamlined upper surface and a lower surface that are symmetrical. ,
It is shaped like an airfoil. And these two rotating blades 14f,
14r is located at a predetermined height above the vehicle body, and is pivotally supported at both ends in the lateral direction of the vehicle body by actuators 16f and 16r, respectively, and these actuators 16f and 16r are supported by support portions 18f and 18r on each side. . For this reason,
By giving a command signal to the actuators 16f and 16r and driving them to rotate, the angle of attack α of the movable blades 14f and 14r relative to the relative wind W can be adjusted individually.

The front wheel side and rear wheel side vertical acceleration sensors 20f and 2Or are installed at positions approximately directly above the front wheels 12f and rear wheels 12r, respectively, and detect vertical acceleration at these positions and generate acceleration signals corresponding to the accelerations. G2. , G2, the controller 22
It is designed to output to . Acceleration signal G2. , G
2. takes a positive value when the vehicle body is excited upward,
Conversely, it is set to take a negative value when it is vibrated downward.

Further, the vehicle speed sensor 21 has a configuration that detects, for example, the rotation speed on the output side of a transmission, and outputs a vehicle speed signal (2) as an absolute air speed to the controller 22. Here, the vehicle speed detection means of the present invention may include a pitot tube.

In this embodiment, the controller 22 inputs the vertical acceleration detection signals czr and GZr for the front and rear wheels, integrates them independently, and multiplies a predetermined gain by 2 to generate the command signals s, , s,'. Input the integrators 211f and 24r as command signal calculation means and the vehicle speed detection signal ■ to [1
7■ Average value calculator 2 that calculates 2j as a correction signal V'
6, and multipliers 28f, 28r that calculate command signals S, , S by multiplying the calculation signals s, , s, ' of the integrators 24f, 24r by the calculation signal V' of the average value calculator 26, respectively. The command signals S, , S, are individually given to both the actuators 16f to 16r. Note that the average value calculator 26 and the multipliers 28f and 28r form the command signal correction means of the present invention.

Here, the command signals S, , Sr, and the movable wing 14r.

The relationship between the angle of attack α of 14r and the aerodynamic force applied to the movable wings 14f and 14r (assuming that only parallel relative wind W is acting on the vehicle) is, when S, , S, −〇, α-0, and the vertical force acting on the movable blades 14f and 14r becomes zero. Also, S.

When Sr is a positive value, the angle of attack α increases downward in the figure in accordance with the signal value, and a downward force (that is, downforce) acts on the movable blades 14f and 14r as an aerodynamic force.

Furthermore, when S,, S, is a negative value, the angle of attack α increases upward in the figure according to the signal value, and the movable blades 14f, 1
An upward force (that is, lift force) acts on 4r as an aerodynamic force.

An example of the external configuration of the swing control device configured in this manner is shown in FIG. 2.

On the other hand, as shown in FIG. 3, a suspension consisting of a coil spring 24 (spring constant k) and a shock absorber 26 (damping constant C) is interposed between the vehicle body 10 and the wheels 12f, 12f. In this embodiment, the damping constant C is set sufficiently small to provide "soft" suspension characteristics.

FIG. 3 shows a model example in which the above configuration is expressed for one front wheel 12f, and this model consists of a vibration model that supports the vehicle body 10 and a skyhook model.

Here, the principle of considering the vehicle speed (2) in the present invention will be explained. It is known that the lift and downforce F generated by the movable wings 14f and 14r are expressed by the following equations.

F=-CL ρV2 A (2) where ρ: air density, A: wing area, CL: lift or downforce coefficient, ■: vehicle speed or airspeed. In other words, when the angle of attack α of the movable wings 14f and 14r is the same, the lift and downforce F that act as forces that dampen vertical motion are proportional to the square of the vehicle speed V, so the movable wing 14f
, 14r is made inversely proportional to the square of the vehicle speed (2), it is possible to prevent over-damping due to an increase in the vehicle speed (2), and to obtain only the truly necessary damping force.

Next, the operation of this embodiment will be explained.

Assume that the vehicle is now traveling on a good road at a predetermined speed. In this state, the front wheel side, rear wheel side vertical acceleration sensor 2Of,
2Or detects the vertical acceleration signal G2. , G2. are both zero, so their integral values, that is, the absolute improvement degrees V 2 f and V 2 r of the vehicle body are both zero, and the command signals S, , S given to both actuators 16f and 16r are
, also becomes zero. This allows the front side.

The angle of attack of the rear movable wings 14f, 14r is adjusted to α-0, and the movable wings 14f, 14r do not generate any force in the vertical direction. Therefore, the only force acting on both rotating blades 14f and 14r is the drag force due to the relative wind W, and the attitude of the vehicle body 10 is maintained at a constant vehicle height by the suspension made up of the coil spring 24 and the shock absorber 26.

In this state, due to small irregularities on the road surface, the wheel 1
Even if there is a relatively high frequency vibration input to 2f and 12r,
The soft suspension characteristics absorb vibrations and provide a comfortable ride.

It is also assumed that, in such a running state, the vehicle passes a protrusion or the like, causing upward acceleration to occur at both the front and rear wheels 12f and 12r, for example (see arrows A and A in FIG. 1). This results in positive detection signals Cr2. of the vertical acceleration sensors 2Of, 2Or. , G2° are integrated by the integrators 24f and 24r of the controller 22, respectively, and the integrated value with a phase lag is the absolute improvement degree of the vehicle body V 2 f ,
As V 2 r increases, the predetermined gain increases.
are respectively multiplied to produce command signals s,,s,'. On the other hand, the vehicle speed ■ in this running state is detected by the vehicle speed sensor 21, and the reciprocal of this square is detected as the correction signal V'. This correction signal V' is multiplied by the command signals s, , s,' in multipliers 28f, 28r, and final command signals Sr, S-, which are inversely proportional to the vehicle speed, are applied to both actuators 18f, 18r.
Supplied separately. Therefore, the actuator 18f,
18r rotates in accordance with the value of the command signal 5tSr, and the angle of attack α of the movable wings 14f and 14r is adjusted so that the front sides of both movable wings 14f and 14r are directed downward. As a result, both rotating blades 14f and 14r
At the same time, a downward force is generated (arrow B in Figure 1).

(see B), the force that urges the vehicle body 10 upward can be attenuated, and the upward movement of the vehicle body can be suppressed.

At this time, as the vehicle speed ■ increases, the movable wings 14f, 1
The slope of 4r is corrected to a small value, and the damping force for damping upward displacement of the vehicle body 10 is also corrected to a small value. This prevents excessive damping force from being generated due to the increase in force caused by an increase in vehicle speed, as in the case of the prior application where the angle of attack α is set regardless of the airspeed. Only the force that is truly desired to be damped remains against the vibration force. by this,
Over-damping at high speeds is prevented, and the good ride quality set by the suspension is maintained as is in the overall ride quality.

On the contrary, if downward acceleration occurs at both the front and rear wheel positions 12f and 12r, the angle of attack α of both rotary blades 14f and 14r is adjusted, contrary to the above. For this reason,
To surely attenuate the force that urges a vehicle body 10 downward while considering the vehicle speed (2), to surely suppress the downward movement of the vehicle body, and to prevent deterioration of riding comfort by eliminating excessive damping.

Furthermore, if accelerations of opposite phases occur at the positions of the front and rear wheels 12f and 12f, the angles of attack α of the front and rear movable wings 14f and 14r are respectively adjusted in the same manner as described above, and The acting biasing forces are attenuated separately, and over-damping is also eliminated.

Here, the qualitative operation described above will be described more quantitatively regarding the case where the vehicle speed (2) is constant.

The model shown in FIG. 3 can be replaced with the equivalent model shown in FIG. 4 based on its function.

In other words, the skyhook model part has a movable wing 14f (1
4r) is a variable damping force shock absorber (damping constant C') corresponding to the aerodynamic force generated in the shock absorber, one end of which is fixed and the other end connected to the vehicle body 10. The transfer function of the equivalent model shown in FIG. 4 is as follows with respect to that of equation (1) described above. Therefore, the vibration transmission characteristics to the vehicle body 10 are determined by setting the damping constant C', which is determined by the shape of the movable blades 14f (14r), sufficiently large, and setting the damping constant C of the shock absorber 26 sufficiently small. By doing so, the characteristic a shown by the solid line in FIG. 5 can be obtained. In other words, the damping constant C' based on the skyhook model is effective in the sprung mass resonance region (around I Hz), and the damping constant C of the suspension is effective in the sprung mass resonance region on the higher frequency side.

Therefore, as in the qualitative explanation above, the vehicle body 10 is supported in a state where its vertical vibration is significantly reduced over the entire vertical vibration frequency range, and the damping force increase due to the increase in vehicle speed is eliminated. As a result, a good riding comfort is always obtained. Here, the characteristic shown by the dotted line in FIG. 5 corresponds to the conventional characteristic when the damping constant C' is set to zero.

In the above embodiment, the vertical motion detecting means calculates the velocity in the vertical direction from the detected value of the vertical acceleration sensor, but a vertical velocity sensor may be provided and the velocity may be directly determined from the sensor output. Alternatively, a stroke sensor that detects the stroke amount of the suspension may be installed at each axis position, and the detected value may be used to detect the vertical movement of the vehicle body.

Furthermore, in the above-mentioned embodiment, when there is no vertical vibration in the vehicle body, the vertical force exerted by each movable wing is set to be zero. It may be set to obtain downforce to improve steering stability.

〔Effect of the invention〕

As explained above, the present invention detects the vertical movement of the vehicle body and the vehicle speed, adjusts the angle of attack of the movable blade relative to the wind according to these detected values, and applies force to the movable blade to damp the vertical vibration of the vehicle body. As a result, the vertical vibration of the vehicle body can be controlled independently of the suspension, and changes in the vertical posture of the vehicle body can be accurately prevented in cooperation with the suspension, and the damping characteristics of the suspension can be made “soft”. However, as the vehicle speed increases, the damping force on the movable blades is corrected to a smaller value, so the good ride quality of the suspension is impaired by over-damping of the movable blades. This has the effect that good ride comfort performance is always exhibited regardless of the vehicle speed.

[Brief explanation of drawings]

1 to 5 are views showing one embodiment of the present invention, in which FIG. 1 is a schematic configuration diagram, FIG. 2 is a perspective view showing an example of the external configuration, and FIG. 3 is a model for each wheel. Figure 4 is an equivalent model diagram of Figure 3, Figure 5 is a graph showing vibration transfer characteristics, Figure 6 is a model diagram showing a conventional suspension, and Figure 7 is a graph showing vibration transmission characteristics of a conventional suspension. It is a graph. In the figure, 10...vehicle body, 14f, 14r...movable wings,
16f, 16r --- actuator, 2Of, 2Or
... Vertical acceleration sensor, 21 ... Vehicle speed sensor, 22
...Controller, 24f, 24r...Integrator, 2
6... Average value calculator, 28f, 28r... Multiplier,
It is. Diagram

Claims (1)

[Claims] (1) A movable wing attached to the vehicle body that can change the angle of attack relative to the wind as the vehicle travels, an actuator that adjusts the angle of attack of the movable wing according to a command signal, and information corresponding to the vertical movement of the vehicle body. vertical motion detection means for outputting the
a command signal calculating means for calculating the command signal according to a damping force for attenuating the vertical movement based on the detected value of the vertical movement detecting means; and a vehicle speed detecting means for detecting the vehicle speed; A vehicle rocking control device comprising command signal correction means for correcting the calculated value of the command signal calculation means so that the damping force becomes weaker as the value increases.