JPH0822650B2 - Front wheel suspension - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a front wheel suspension system for an automobile, and more particularly, to an independent suspension system that is provided with means for varying the rigidity in the front-rear direction in order to prevent a so-called flutter phenomenon. Type front wheel suspension.

(Prior Art) Flutter appears as an uncomfortable vibration in the circumferential direction of a steering wheel due to an imbalance of an automobile tire and the like, and as shown in FIG. And shows a peak level in a specific vehicle speed range.

Conventionally, in order to reduce such flutter, a steering system rigidity reducing means such as a rubber coupling is generally inserted into an intermediate shaft of the steering system.

On the other hand, for example, Japanese Utility Model No. 55-166073 (Japanese Utility Model Sho 58-8860).
As described in the specification attached to the application of No. 6) and the invention described in the drawings, by means such as different hardness or dimensions of the rubber bush of the connecting portion between the strut bar and the vehicle body in the suspension device of the left and right front wheels, The front and rear direction rigidity of the left and right front wheel suspensions is formed asymmetrically, and as shown in FIG.
In some systems, the flutter level characteristics A and B corresponding to the left and right suspension devices are offset to obtain a flutter level characteristic C that has a relatively low peak and appears slowly.

(Problems to be Solved by the Invention) However, in the former conventional example, there is a problem that the steering stability is inevitably deteriorated as the rigidity of the steering system decreases, and in the latter conventional example, such a problem occurs. Although the flutter level peak can be lowered without causing it, the fundamental problem of the flutter level characteristic that the flutter level shows a peak in a specific vehicle speed range has not been solved.

Therefore, an object of the present invention is to provide a front wheel suspension system in which the flutter level does not show a peak in a specific vehicle speed range.

(Means for Solving the Problems) Therefore, according to the present invention, the front side connecting portion with respect to the vehicle body is elastically supported so as to be displaceable in the front-rear direction, and the rear side connecting portion is elastically supported so as to be displaceable in the front-rear direction and the left-right direction. Independent suspension type front wheel suspension device having a pair of left and right suspension arms, which is provided so that a restriction member can be brought into contact with and separated from the suspension arm, and the restriction member is brought into contact with and separated from the suspension arm based on a vehicle speed. It is characterized in that it is configured to regulate the amount of lateral displacement of the side connecting portion.

(Operation) According to the above configuration, the restricting member is moved toward and away from the vehicle based on the change in the vehicle speed, thereby restricting the displacement amount of the front and rear connecting portions of the suspension arm, and by extension, the supporting rigidity of the suspension arm. Is regulated.

Here, in a certain suspension system, the vehicle speed V0 at which the flutter level peaks is V0 = 2π · R · f (π is the circular constant, R is the tire radius, and f is the front-rear resonance frequency of the suspension system). And f = 1 / 2π · (K / M) ^1/2 (where K is the longitudinal rigidity of the suspension system and M is the unsprung mass).

According to this, V0 increases in proportion to the square root of K. Therefore, for example, as shown in FIG. 8, when the value of the rigidity K in the front-rear direction is changed in the same suspension system, the vehicle speed range showing a peak is obtained. Two different flutter level characteristic curves
It can be seen that a and b are obtained.

Therefore, if a high longitudinal rigidity value corresponding to the curve b is set in the vehicle speed range V1 and a low longitudinal rigidity value corresponding to the curve a is set in the vehicle speed range V2 shown in FIG. The device does not show the peak of flutter level in each vehicle speed range, so that the flutter phenomenon as perceived by the driver of the vehicle can be virtually prevented.

From the above, the peak of the flutter level can be avoided by changing the rigidity of the suspension device in the front-rear direction, specifically, the support rigidity of the suspension arm according to the vehicle speed (vehicle running state), and in all vehicle speed ranges. The flutter phenomenon can be virtually prevented.

(Embodiment) Next, an embodiment of the present invention will be described with reference to FIGS.

The front wheel suspension system of the present embodiment is of a so-called MacPherson type, and a pair of left and right L-shaped suspension arms 1 are connected to the vehicle body via a front side connecting portion 2 and a rear side connecting portion 3, respectively. There is.

As shown in FIG. 2, the front connecting portion 2 has a pipe-shaped supporting member 4 protruding from the suspension arm 1.
Is connected to a fixing member 6 to the vehicle body via a rubber bush 5, and the supporting member 4 is elastically deformed by the rubber bush 5 so that the supporting member 4 has a predetermined width with respect to the fixing member 6 (upper and lower directions in FIG. 1). Direction) The degree of freedom of fine movement is given.

Next, as shown in FIG. 3, the rear side connecting portion 3 is a U-shaped fixing in which the rear end portion 7 of the suspension arm 1 formed in a pipe shape is fixed to the vehicle body via the rubber bush 8. The end portion 7 is provided with a degree of freedom of fine movement in the front-back direction and the left-right direction (left-right direction in FIG. 1) of a predetermined width with respect to the fixture 9 due to the elastic deformation of the rubber bush 8. ing.

Therefore, the suspension arm 1 moves in the longitudinal direction about the front connecting portion 2 within a range in which the linear movement in the front-rear direction relative to the vehicle body and the fine movement in the left-right direction at the rear connecting portion 3 are allowed. (Direction of arrow Z in FIG. 1) is possible.

The wheel-side end 10 of the suspension arm 1 is connected to a knuckle arm (not shown) via a shock absorber (not shown) to support the tire 11.

Next, at the rear end of the rear side end portion 7 of the suspension arm 1, an outer end portion of a regulating shaft 13 provided in the vehicle body left-right direction is provided via a spherical bush 12 having a degree of freedom of rotation and swing. It is connected. The regulating shaft 13 is elastically supported at its middle portion by a rubber supporting member 14 with respect to the vehicle body, and the regulating receiving members 15 are integrally formed at the inner ends of the pair of regulating shafts 13. Has been done.

The restriction receiving member 14 is a semi-cylindrical member, and the inner peripheral surface thereof is a conical taper receiving surface 16, and the pair of left and right restricting receiving members 15 have the receiving surfaces 16 mutually. They are provided so as to be close to each other in a state of facing each other.

Next, the regulating member 17 having a conical outer peripheral surface corresponding to the receiving surface 16 is slidably attached to the support shaft 18 fixed to the vehicle body at the center of the pair of receiving surfaces 16 and is always The compression spring 19 wound around the support shaft 18 urges it upward (in the front of the vehicle body) in the drawing, and is positioned while being pressed against a washer 21 fixed by a nut 20 fixed to the support shaft 18.

On the other hand, one end of a cord member 22 such as a wire is attached to the lower end of the regulating member 17 in the drawing, and the other end of the cord member 22 is connected to a winding device 23 equipped with a motor. And
As shown in FIG. 5, this motor rotationally drives the winding device 23 when a signal generated from a sensor 24 for detecting the traveling speed of the vehicle body is input to the computer 25 to operate the drive source 26. It is designed to work.

The present embodiment configured as described above is used as follows.

When the winding device 23 does not operate, the regulating member 17 is in a position in which it is pressed against the washer 21 by the compression spring 19, so that the regulating member 17 and the receiving surface 16 of the regulating receiving member 15 as shown in FIG. A space having a constant width is held between them. Therefore, the movement of the regulating shaft 13, and by extension, the rear end portion 7 of the suspension arm 1 is not regulated by the regulating member 17, so that the suspension arm 1 is allowed to perform the fine movement in the front-rear direction and the fine movement of the swing.

If the flutter level characteristic curve of the front wheel suspension system in this state is the curve a in FIG. 8, the flutter level reaches its peak in the vehicle speed range V1.

However, when the vehicle speed approaches the vehicle speed range V1 from the constant speed side or the high speed side, based on the signal of the sensor 24 that detects this, the winding device 23 operates and the rope member 22 is wound for a certain length. Therefore, the regulating member 17 is pressed against the receiving surface 16 of the regulating receiving member 15 against the elastic force of the compression spring 19.

Therefore, the rear side end portion 7 of the suspension arm 1 is restricted from moving in the left-right direction in the figure, and the suspension arm 1 loses the freedom of the fine swinging motion and is allowed to perform only the fine linear motion in the front-rear direction.

This means that the rigidity of the front wheel suspension system in the front-rear direction is increased, so that the peak of the flutter level shifts to the high speed side. If the flutter level characteristic curve in this state is the curve b in FIG. 8,
In the vehicle speed range V1, the flutter level does not show a peak,
It will be suppressed to an extremely low level.

Further, when the vehicle speed approaches the vehicle speed range V2, the rigidity in the front-rear direction of the front wheel suspension device is reduced by the operation opposite to the above operation, and the flutter level is similarly suppressed by setting the flutter level characteristic curve to the curve a. be able to.

As described above, by making the support rigidity (especially, the rigidity in the front-rear direction) of the front wheel suspension system of the automobile variable, the peak of flutter is avoided in all the vehicle speed ranges, and eventually the flutter phenomenon is effectively prevented. become. Moreover, since the front and rear direction rigidity varying means is automatically operated, erroneous operation when the driver manually operates is avoided,
Further, the burden on the driver does not increase.

(Effect of the Invention) According to the present invention, since the support rigidity of the suspension arm is changed according to the vehicle speed, the peak of the flutter level can be avoided, and the flutter phenomenon can be virtually prevented in all vehicle speed ranges.

[Brief description of drawings]

FIG. 1 is a plan view schematically showing an embodiment of the present invention, FIG.
FIG. 4 is a sectional view taken along the line XX, FIG. 3 is a sectional view taken along the line YY of FIG. 1, FIG. 4 is a sectional view of the essential portion of FIG. 1, and FIG. 5 is a block diagram of an electric control circuit of the same embodiment. FIG. 6 is a diagram showing a general flutter level characteristic curve, FIG. 7 is a diagram showing a flutter level characteristic in a conventional example, and FIG. 8 is a diagram showing a flutter level characteristic in the present invention. 1 …… Suspension arm 2,3 …… Coupling part 5,8 …… Rubber bush 15 …… Regulator receiving member 17 …… Regulator member 22 …… Rope member 24 …… Sensor

Claims (1)

[Claims] 1. An independent suspension type having a pair of left and right suspension arms in which a front-side connecting portion with respect to a vehicle body is elastically supported so as to be displaceable in the front-rear direction, and a rear-side connecting portion is elastically supported so as to be displaceable in the front-rear and left-right directions. In the front wheel suspension device, a restriction member is provided so as to be able to come into contact with and separate from the suspension arm, and the regulation member is operated to come into contact with and separate from the suspension arm based on a vehicle speed to regulate a lateral displacement amount of the rear-side connecting portion. A front wheel suspension device having the above structure.