JP4939310B2 - Strut suspension system - Google Patents

Description

According to the present invention, a knuckle that rotatably supports a wheel on a wheel support portion is formed with a lower arm that extends downward from the wheel support portion and an upper arm that extends upward, and the lower arm is provided at a lower portion of a shock absorber with a first pivot portion. The upper arm is connected to the tip of an arm extending outward in the vehicle width direction from the upper part of the shock absorber via a second pivotal support portion, and the inner end in the vehicle width direction is connected to the vehicle body via a compliance bush. An outer end in a vehicle width direction of a lower arm connected to be vertically movable is connected to a lower part of a shock absorber in the vicinity of the first pivotal support, and the shock absorber and the lower arm are connected via a link, The present invention relates to a strut-type suspension device that steers a wheel around a kingpin axis connecting a second pivot.

  A conventional strut suspension device for a front wheel connects the outer end of the lower arm in the vehicle width direction and the lower end of the knuckle, and connects the lower end and upper end of the shock absorber to the upper end of the knuckle and the vehicle body, respectively. It was steered around the kingpin axis connecting the connection point to the vehicle body at the upper end and the connection point to the lower arm at the lower end of the knuckle. However, the above-described conventional strut suspension device has a large kingpin offset (the distance between the point where the downward extension of the kingpin shaft intersects the road surface and the center of the tire ground contact surface). There was a problem that a large moment was generated around the shaft and the steering wheel was removed. To solve this problem, if you try to reduce the kingpin offset by setting a large kingpin angle (the angle that the kingpin axis forms with the vertical line when viewed in the longitudinal direction of the vehicle), the force required for steering increases. A new problem that the operability deteriorates occurs.

Therefore, in Patent Document 1, the lower arm and the upper arm provided on the knuckle are connected to the shock absorber via two connecting shafts, and a straight line connecting the two connecting shafts is used as a kingpin shaft. This reduces the kingpin offset.
JP-A 61-146609

  However, since the two connecting shafts that connect the knuckle to the shock absorber are arranged on the inner peripheral portion of the tire, the vertical span between the two connecting shafts is small. Therefore, there is a problem that caster rigidity and camber rigidity are reduced when a longitudinal force or a lateral force is applied to the wheel. In addition, if the upper part of the shock absorber is tilted backward to ensure the caster angle, the component of the reaction force of the shock absorber in the longitudinal direction of the vehicle will increase, and the inner end of the lower arm in the vehicle width direction will be connected to the compliance bush that connects to the vehicle body. There is a problem that the ride comfort performance deteriorates due to the load.

  The present invention has been made in view of the above-described circumstances, and it is an object of the present invention to increase the caster rigidity and camber rigidity of a strut suspension device and reduce the load in the longitudinal direction of the vehicle body input from the shock absorber to the lower arm.

To achieve the above object, according to the first aspect of the present invention, a knuckle that rotatably supports a wheel on a wheel support portion includes a lower arm that extends downward from the wheel support portion and an upper arm that extends upward. The lower arm is connected to the lower part of the shock absorber via the first pivotal support part, and the upper arm is connected to the tip of the arm extending outward in the vehicle width direction from the upper part of the shock absorber via the second pivotal support part. The lower end of the lower arm, which is connected to the vehicle body via the compliance bush so as to move up and down in the vehicle width direction, is connected to the lower part of the shock absorber in the vicinity of the first pivot portion. And a lower arm connected via a link, and a strut suspension for turning a wheel around a kingpin shaft connecting the first and second pivots. A location, when viewed in the vehicle width direction, wherein disposed on the rear side of the vehicle body than the center of the wheel as well as arranged in a substantially vertical direction to the axis of the shock absorber, the upper end of the wheel of the second pivot portion A strut-type suspension device is proposed, which is disposed above and on the rear side of the vehicle body with respect to the axis of the shock absorber , and the first pivotal support portion is disposed on the front side of the vehicle body with respect to the center of the wheel .

  According to the second aspect of the present invention, in addition to the structure of the first aspect, the suspension spring for buffering the vertical movement of the lower arm is a torsion bar spring connected to the inner end in the vehicle width direction of the lower arm. A strut suspension device is proposed which is characterized in that it is constructed.

The upper arm 13c of the shock absorber 13 of the embodiment corresponds to the arm of the present invention, and the first and second pin joints 20 and 21 of the embodiment correspond to the first and second pivot portions of the present invention.

  According to the first aspect of the present invention, the lower arm extending upward and the upper arm extending upward from the wheel support portion of the knuckle are connected to the lower and upper portions of the shock absorber via the first pivot portion and the second pivot portion, respectively. The kingpin offset can be reduced without increasing the kingpin angle, and the problem that the steering wheel is taken by the external force input to the wheel from the road surface can be solved.

  In addition, since the second pivotal support that connects the upper arm of the knuckle to the upper part of the shock absorber is located above the upper end of the wheel, the span between the lower arm and upper arm of the knuckle is secured sufficiently long and the wheel is input to the wheel. The caster rigidity and camber rigidity can be increased by making it difficult for the knuckle to fall against the longitudinal force and lateral force.

The axis of the shock absorber is arranged vertically when viewed from the side of the vehicle body, the first pivot connecting the lower arm to the lower part of the shock absorber is arranged on the vehicle body front side of the wheel center, and the upper end of the upper arm only because the second pivot portion for coupling to the upper portion of the shock absorber disposed on the vehicle body rear side of the axis of the shock absorber, can reduce the kingpin offset while securing the caster angle necessary increase the camber stiffness In addition, the load in the longitudinal direction of the vehicle body is prevented from being input from the shock absorber to the lower arm, so that the compression bushing and tensile load are not applied to the compliance bush that connects the inner end of the lower arm in the vehicle width direction to the vehicle body. Performance degradation can be avoided, and the caster angle and casters are increased with the wheel stroke. Rail is prevented from changing can be enhanced straight running stability of the vehicle.

  Furthermore, since the shock absorber and the lower arm are connected via the link, it is possible to prevent the shock absorber from rotating around its own axis by an external force input from the road surface via the wheel.

  According to the second aspect of the present invention, the suspension spring is constituted by a torsion bar spring connected to the inner end in the vehicle width direction of the lower arm, so that a suspension spring comprising a coil spring is disposed on the outer periphery of the shock absorber. In addition to increasing the degree of freedom in layout, the spring rate of the torsion bar spring is suddenly increased in response to an increase in the upward stroke of the wheel, thereby suppressing the increase in the roll angle when turning the vehicle and improving the riding comfort performance. Can do.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples of the present invention shown in the accompanying drawings.

  1 to 4 show a first embodiment of the present invention. FIG. 1 is a perspective view of a strut type suspension device, FIG. 2 is a view in the two-direction direction of FIG. 1, and FIG. FIG. 4 is a graph showing the relationship between the vertical stroke of the wheel and the caster angle.

  As shown in FIGS. 1 to 3, the strut type suspension device S for a front wheel that can be steered includes a lower arm 11, a knuckle 12, a shock absorber 13, a suspension spring 14, and a stabilizer 15.

The lower arm 11 is a so-called A-type arm, and the inner end of the bifurcated inner side in the vehicle width direction moves up and down to the vehicle body 18 (only a part is shown) via the compliance bush 16 on the front side of the vehicle body and the compliance bush 17 on the rear side of the vehicle body. It is pivotably supported. The knuckle 12 includes a wheel support 12a that rotatably supports the wheel W, a short lower arm 12b that extends downward from the wheel support 12a, and a long upper arm 12c that extends upward from the wheel support 12a. The shock absorber 13 includes a telescopic hydraulic cylinder 13a, a lower arm 13b extending obliquely downward from the lower end of the hydraulic cylinder 13a, and an upper arm 13c extending obliquely upward from the upper end of the hydraulic cylinder 13a toward the outside in the vehicle width direction. Prepare.

The outer end of the lower arm 11 in the vehicle width direction and the lower arm 13 b of the shock absorber 13 are pivotally supported via a ball joint 19. The lower arm 12b of the knuckle 12 and the lower arm 13b of the shock absorber 13 are connected by the first pin joint 20 constituting the first pivotal support portion of the present invention, and the upper arm 12c of the knuckle 12 and the upper part of the shock absorber 13 are connected. The arm 13c is connected to the second pin joint 21 constituting the second pivotal support portion of the present invention. The upper arm 12c of the knuckle 12 extends upward while curving outward from the vehicle body after being curved inward from the wheel support portion 12a. As a result, the second pin joint 21 is positioned above the upper end of the wheel W. is doing.

  The lower arm 13 b of the shock absorber 13 and the lower arm 11 are connected by a link 25. One end of the link 25 is pivotally supported at a position near the lower end of the lower arm 13b of the shock absorber 13 via the ball joint 26, and the other end of the link 25 is located near the base end of the upper surface of the lower arm 11 via the ball joint 27. It is supported by. With this link 25, it is possible to prevent the hydraulic cylinder 13a of the shock absorber 13 from rotating about its own axis by an external force input from the road surface while allowing relative movement of the shock absorber 13 and the lower arm 11. .

The axis of the shock absorber 13 is arranged in a vertical direction as viewed from the side of the vehicle body (the direction perpendicular to the road surface), and Ru are arranged in the rear of the vehicle body with respect to the center of the wheel W. The first and second pin joints 20 and 21 arranged coaxially cooperate to define the kingpin axis K. When viewed from the side of the vehicle body, the kingpin axis K has an angle θ ( The kingpin axis K is inclined inward of the vehicle body by an angle α (kingpin angle) with respect to the vertical direction as viewed from the front of the vehicle body.

  The suspension spring 14 is coaxially disposed on the outer periphery of the upper portion of the shock absorber 13 and expands and contracts according to the expansion and contraction of the hydraulic cylinder 13 a of the shock absorber 13. An end portion of the stabilizer 15 arranged in the left-right direction of the vehicle body is connected to an intermediate portion of the lower arm 11 via a link 22 and is torsionally deformed in accordance with the vertical movement of the lower arm 11. A tie rod 23 extending from a steering gear box (not shown) is connected to the rear part of the knuckle 12. When the tie rod 23 moves left and right, the wheel W supported by the knuckle 12 is steered around the kingpin axis K.

  Next, the operation of the embodiment of the present invention having the above configuration will be described.

  When the driver operates the steering wheel, the tie rod 23 pushes and pulls the knuckle 12 so that the wheel W is steered right and left about the kingpin axis K connecting the first and second pin joints 20 and 21. In conventional strut suspension systems, the knuckle is steered around the kingpin axis that connects the connection point of the shock absorber to the vehicle body at the upper end and the connection point to the lower arm at the lower end of the knuckle. Although difficult, in this embodiment, the kingpin axis K is defined by the lower arm 12b and the upper arm 12c of the knuckle 12, thereby reducing the kingpin offset δ without increasing the kingpin angle α as shown in FIG. The problem that the steering wheel is taken by the external force input to the wheel from the road surface can be solved.

  When the vehicle suddenly accelerates or brakes suddenly, a longitudinal force acts on the wheel W, and when the vehicle turns, a lateral force acts on the wheel, and these longitudinal force and lateral force are moments that cause the knuckle 12 to tilt forward, backward, left and right. Is generated. However, since the knuckle 12 of this embodiment has the upper arm 12c extending upward beyond the upper end of the wheel W, the span L (see FIG. 2) between the lower arm 12b and the upper arm 12c is secured sufficiently long. As a result, the knuckle 12 can be prevented from falling with respect to the moment input, and the caster rigidity and the camber rigidity can be increased.

Since the axis of the shock absorber 13 is arranged in the vertical direction when viewed from the side of the vehicle body, and the second pin joint 21 at the upper end of the upper arm 12c is arranged behind the vehicle body from the axis of the shock absorber 13 , the center of the wheel W In addition , the second pin joint 21 can be positioned rearward of the first pin joint 20 positioned in front of the vehicle body , and the necessary caster angle θ can be ensured. At this time, since the axis of the shock absorber 13 is arranged in the vertical direction when viewed from the side of the vehicle body, the ball joint 19 at the outer end in the vehicle width direction of the lower arm 11 moving up and down in the vertical direction is connected to the front and rear of the vehicle body from the shock absorber 13. No direction load is entered. Therefore, the load inputted from the shock absorber 13 prevents the compression bushing or tensile load in the vehicle width direction from acting on the pair of compliance bushes 16 and 17 at the inner end in the vehicle width direction of the lower arm 11, thereby reducing the riding comfort performance. It can be avoided.

Further, by arranging the axis of the shock absorber 13 in the vertical direction when viewed from the side of the vehicle body, as shown in the graph of FIG. 4, even if the shock absorber 13 expands and contracts, the caster angle β (caster rail T) shown in FIG. ) Does not change, and the straight running stability of the vehicle can be prevented from changing according to the stroke of the wheel W.

  FIGS. 5 and 6 show a second embodiment of the present invention. FIG. 5 is a perspective view of a strut suspension device, and FIG. 6 is a graph showing the relationship between the vertical stroke of the wheel and the vertical load of the wheel.

  In the strut suspension S of the first embodiment, the suspension spring 14 made of a coil spring is arranged on the outer periphery of the upper part of the shock absorber 13, but the strut suspension S of the second embodiment is a torsion bar that extends in the longitudinal direction of the vehicle body. A suspension spring 24 made of a spring is disposed at the inner end in the vehicle width direction of the lower arm 11. That is, the suspension spring 24 of the second embodiment has one end fixed to the lower arm 11 at the position of the compliance bush 16 and the other end fixed to the vehicle body 18. Therefore, when the wheel W strokes up and down and the lower arm 11 swings up and down, the suspension spring 24 is twisted by the swing angle.

  Since the torsion bar spring has a characteristic that the load increases non-linearly with an increase in the twist angle, as shown in FIG. 6, when the wheel W strokes upward, the load is increased according to the increase in the stroke. Will increase rapidly. As a result, when the vehicle body rolls outward in the turning direction while the vehicle is turning, the load of the suspension spring 24 is suddenly raised as the turning outer wheel strokes upward, so that the rook angle of the vehicle body does not increase excessively. The ride comfort performance can be improved.

  Other configurations and effects of the second embodiment including the structure in which the lower arm 11 and the shock absorber 13 are connected by the link 25 to prevent the shock absorber 13 from rotating are the same as those of the first embodiment described above.

  Although the embodiments of the present invention have been described above, various design changes can be made without departing from the scope of the present invention.

The perspective view of the strut type suspension device concerning the 1st example. 2 direction view of FIG. 3 direction arrow view of FIG. Graph showing the relationship between wheel vertical stroke and caster angle A perspective view of a strut suspension device according to a second embodiment. Graph showing the relationship between the vertical stroke of the wheel and the vertical load of the wheel

11 Lower arm 12 Knuckle 12a Wheel support 12b Lower arm 12c Upper arm 13 Shock absorber
Upper arm (arm) of 13c shock absorber
16 Compliance bush 17 Compliance bush 18 Body 20 First pin joint (first pivot)
21 Second pin joint (second pivot)
24 Suspension spring 25 Link K Kingpin shaft W Wheel

Claims (2)

A lower arm (12b) extending downward from the wheel support (12a) and an upper arm (12c) extending upward from the wheel support (12a) are formed on the knuckle (12) which rotatably supports the wheel (W) on the wheel support (12a). The lower arm (12b) is connected to the lower part of the shock absorber (13) via the first pivotal support part (20), and the upper arm (12c) is connected to the outer side in the vehicle width direction from the upper part of the shock absorber (13). The lower arm is connected to the tip of the arm (13c) that extends to the vehicle body via the second pivotal support (21), and the inner end in the vehicle width direction is connected to the vehicle body (18) via the compliance bushes (16, 17) so as to be vertically movable. The outer end in the vehicle width direction of (11) is connected to the lower part of the shock absorber (13) in the vicinity of the first pivot (20), and the shock absorber (13) and the lower arm ( 1) and the via link (25) connecting said first, met strut suspension system for steering the wheel (W) to the second pivot kingpin axis connecting the branch (20, 21) (K) around And
When viewed in the vehicle width direction, the axis of the shock absorber (13) is arranged in a substantially vertical direction and at the rear side of the vehicle body from the center of the wheel (W) , and the second pivot (21) is arranged on the wheel. (W) is located above the upper end of the shock absorber (13) and on the rear side of the vehicle body relative to the axis of the shock absorber (13) , and the first pivot (20) is located on the front side of the vehicle body with respect to the center of the wheel (W). A strut type suspension device characterized by being arranged .   The suspension spring (24) for buffering the vertical movement of the lower arm (11) is constituted by a torsion bar spring connected to an inner end in the vehicle width direction of the lower arm (11). Strut suspension system.

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