JP3209467B2 - Rear wheel suspension device for automobile - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension system for suspending a rear wheel of an automobile, and more particularly, to a compliance steer for automatically rearwardly moving the rear wheel to a toe-in or toe-out side by utilizing a damping force generated by a shock absorber. The present invention relates to a rear wheel suspension device for an automobile.

[0002]

2. Description of the Related Art As this kind of rear wheel suspension device for an automobile, the rear wheel is automatically steered to the toe-in side by utilizing the compression side generated damping force of a telescopic hydraulic cylinder type shock absorber accompanying an increase in rear wheel load. For example, in Japanese Patent Application Publication No.
Has already been proposed.

That is, this is a double trailing link type rear wheel suspension device having a compliance function, which is constituted by a telescopic hydraulic cylinder between a support link (lower arm) for swingably supporting an axle housing and a vehicle body. The shock absorber is mounted diagonally.

Thus, the reaction force of the pressure-side generated damping force during the operation of the shock absorber accompanying the load change of the rear wheel is input to the support link, and the input force is applied to the support link via the support link by a component force in the forward direction of the vehicle body. The rear wheels are compliant steered toward the toe-in side while the axle housing is compliant with the front of the vehicle.

Alternatively, in place of the above, a difference is given to the lateral elastic force of the mount insulator before and after the compliance function is given to the support link, and the support link based on the pressure-side generated damping force of the shock absorber. Using the component force in the lateral direction of the vehicle input, the compression force and the extension force are applied to the front and rear mount insulators to elastically deform the vehicle body in the horizontal direction, and the elastic force difference between these front and rear mount insulators The support link is compliant with the front of the vehicle body, and the rear wheel is compliant steered toward the toe-in side through the axle housing.

[0006]

As described above, in this type of rear wheel suspension apparatus for a vehicle proposed heretofore, regardless of the moment control and the component force control, a telescopic hydraulic cylinder type shock absorber is used. The support link is compliant in the front direction of the vehicle body using the horizontal component of the reaction force based on the generated damping force, and the rear wheel is compliant steer to the toe-in side from the support link through the axle housing.

Therefore, needless to say, the horizontal component of the reaction force based on the compression-side generated damping force of the shock absorber is large enough to cause the rear wheel to steer to the toe-in side through the support link and the axle housing. Must be something.

However, on the other hand, the original function of the shock absorber is to suppress the vertical vibration generated between the vehicle body and the wheels depending on the road surface condition to improve the riding comfort or protect the cargo. The pressure-side generated damping force characteristic (damping force curve according to the compression speed) of the shock absorber is
The optimum value must be set according to the vehicle type and vehicle weight.

Means for satisfying the above two points include:
By setting the compression-side generated damping force of the shock absorber high and increasing its mounting angle, the horizontal component of the reaction force based on the compression-side generated damping force is increased while the vertical component is reduced to obtain the desired compression-side generated force. It is considered that the damping force characteristics can be ensured.

However, in this case, since the mounting angle of the shock absorber greatly changes due to a change in the vehicle height due to an increase or decrease in occupants or the load, the intended mounting angle range greatly deviates from the intended mounting angle range. The inconvenience that the vibrating function cannot be performed occurs.

However, if the mounting angle is set so that the change in vehicle height does not adversely affect the compression-side generated damping force characteristic of the shock absorber as much as possible, the compression-side generated damping characteristic originally reduces the damping effect effectively. In order to demonstrate, it is usually set lower than the extension side generated damping force, so that the horizontal component of the reaction force based on the compression side generated damping force cannot be sufficiently taken, and the expected compliance There is a disadvantage that steering cannot be performed.

As described above, it is difficult to adjust the pressure-side generated damping force only by the mounting angle of the shock absorber so as to maintain the optimum control force for both the damping action against the vertical vibration of the vehicle body and the compliance steering action. .

Accordingly, an object of the present invention is to provide a novel structure capable of independently adjusting both the damping action against the vertical vibration of the vehicle body and the compliance steering action so as to maintain the optimum control force. An object of the present invention is to provide a rear wheel suspension device for a vehicle.

[0014]

According to one aspect of the present invention, a rear wheel is provided with a toe-in or toe-out corresponding to the direction of the force when the force is applied to the axle in the front-rear direction. In a rear wheel suspension device having a compliance function of automatically turning to the side, a rotary damper is used as a shock absorber for attenuating vertical vibration of a vehicle body, and a spring is provided via an arm of the rotary damper and a link connected to the arm. The upper vehicle body and the unsprung rear wheel support mechanism are connected to each other, and furthermore, the link is arranged so as to always keep the rearward inclination within the entire operating angle range of the arm in the rotary damper. .

[0015]

[0016]

That is, by adopting the above structure, for example, when the vehicle starts turning and the vehicle body leans outward due to the roll moment, the outer and inner rotary dampers in the turning direction are opposite to each other through the respective links. The pressure damping torque (damping force toward the sinking side of the vehicle body) is generated by these rotary dampers outside the turning direction.
Also, on the inside, an extension side damping torque (a damping force on the vehicle body rising side) is generated.

Therefore, due to the resistance of these compression side and extension side damping torques, the connection point between the link and the rear wheel support mechanism is:
An external force applied to the rear wheel support mechanism and a force along an axial direction of the link corresponding to the operating angle of the link are applied, and this force is used as a downward supporting force on the outside in the turning direction and as an opposite upward pulling force on the inside. Works.

As a result, on the outer side in the turning direction, the vertical component of the downward supporting force acts as a pressure-side generated damping force for attenuating the vertical vibration of the vehicle body, and the front-rear component becomes a compliance control force to provide the rear wheel support. Push the mechanism forward.

Conversely, on the inner side in the turning direction, the vertical component of the upward pulling force acts as an extension-side generated damping force for attenuating the vertical vibration of the vehicle body, and the longitudinal component serves as a compliance control force for the rear wheels. Pull the support mechanism backwards.

Thus, the left and right rear wheels supported by the rear wheel support mechanism are toe-in on the outside in the turning direction by a compliance control force having a magnitude corresponding to the operating angle of the link and the compression-side and extension-side damping forces of the rotary damper. On the inside, the vehicle is steered to the toe-out side.

As described above, the compliance control force for turning the outer and inner rear wheels in the turning direction in a predetermined direction depends on the compression-side or extension-side generated damping force of the rotary damper and the operating angle of the link, and the magnitude and direction of the compliance control force. Is set.

Accordingly, the vertical vibration damping effect of the vehicle body is as follows.
The compliance control force is set by selecting the compression-side and extension-side generated damping force characteristics of the rotary damper. The compliance control force changes the length of the link including the arm of the rotary damper, and shifts the mounting point of the rotary damper accordingly. This allows setting by changing the operating angle of the link.

Accordingly, the vertical vibration damping function and the compliance control function of the vehicle body can be set independently of each other, so that an ideal damper and compliance steer can be configured.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the drawings. The present embodiment illustrates a case where the present invention is applied to a double trailing link type suspension device.

In FIGS. 1 and 2, the left and right rear wheels 1
Are rotatably supported via respective axle housings 4 connected to the vehicle body 3 by lateral rods 2, and are rotatably driven through these axle housings 4 and axles 5 connected to the axle housings 4.

The axle housing 4 is swingably connected to a portion of the vehicle body 3 on the front side by an upper link 6 and a lower link 7 which are a pair of support links arranged vertically above and below the axle 5, and Rubber bushes 8 to 11 are interposed at the connecting portions of the upper link 6 and the lower link 7, respectively.

A suspension spring 12 is interposed between the upper surface of the axle housing 4 and the portion of the vehicle body 3 above the axle housing 4. Thus, the left and right rear wheels 1 are moved relative to the body 3 above the spring. The axle housing 4, the pair of upper link 6 and the lower link 7, and the suspension spring 12 are elastically supported so as to be compliant with each other via the suspension spring 12.

In the double trailing link type suspension apparatus having the above structure, in this embodiment, a rotary damper 13 is mounted on the vehicle body 3 at a position behind the left and right axle housings 4. The tip of the arm 14 of the rotary damper 13 is connected by a link 15 to a portion of the axle housing 4 eccentric rearward from the axle 5.

According to the rear-wheel suspension device described above, when the car starts turning, the body 3 tilts outward due to the roll moment, and the rotary damper 13 on the outside in the turning direction raises the tip of the arm 14 by the link 15 upward. The rotary damper 13 generates a compression damping torque by the rotation of the rotary damper 13.

The rotary damper 13 on the inner side in the turning direction
When the tip of the arm 14 is pulled downward through the link 15, the arm 14 rotates in the opposite direction to the above, and the rotation of the rotary damper 13 generates an extension-side damping torque.

Now, consider the relationship between the forces acting on the connection points e and f of the arm 14 and the link 15 during the above operation with reference to FIG. An external force C caused by the roll of the vehicle body 3 acts vertically upward on the 15 connection points e.

The vertically upward external force C is applied to the link 1
5, a pressing force F having a magnitude corresponding to the operating angle θ of the link 15 at that time is applied to the connection point f between the link 15 and the arm 14 of the rotary damper 13.

Thus, the connection point f between the link 15 and the arm 14 of the rotary damper 13 receives the pressing force F together with the pressing force F when the arm 14 of the rotary damper 13 rotates clockwise. A resistance G due to the compression damping torque of the rotary damper 13 corresponding to the angular velocity ω of the arm 14 is applied.

The resultant force H of the pressing force F and the resistance force G is absorbed as a force for pulling the arm 14 of the rotary damper 13 in the axial direction.

Thus, at the connection point e between the axle housing 4 and the link 15, a supporting force P, which is a reaction force of the pressing force F, is generated along the axial direction of the link 15, and the supporting force P is increased and decreased. The directional component acts as a pressure-side generated damping force R for attenuating the vertical vibration of the vehicle body 3, and the compliance control force Q, which is a longitudinal component, pushes the axle housing 4 from rear to front.

Therefore, the axle housing 4 has a compliance control force Q of a magnitude corresponding to the operating angle θ of the link 15 and the compression-side generated damping force R of the rotary damper 13.
As a result, the rubber bushes 8 to 11 interposed at the respective connecting portions of the upper link 6 and the lower link 7 are operated while deforming, and the rear wheel 1 is steered to the toe-in side.

On the other hand, in the inside of the turning direction, FIG.
As can be seen from the above, the direction of the force relation acting on each of the connection points e and f is completely opposite to the case where the direction is outside the turning direction.

That is, a downwardly directed external force T acts in a direction opposite to the external force C on the connection point e between the axle housing 4 and the link 15. Rotary damper 13
The link 15 at that time with respect to the connection point f of the arm 14
Exerts a tensile force F having a magnitude corresponding to the operating angle θ.

Thus, at the connecting point f between the link 15 and the arm 14 of the rotary damper 13, when the arm 14 of the rotary damper 13 rotates counterclockwise by receiving the above-mentioned tensile force F and the tensile force F. A resistance G due to the extension damping torque of the rotary damper 13 corresponding to the angular velocity ω of the arm 14 acts, and a resultant H of the tensile force F and the resistance G is applied.
Acts as a force to pull the arm 14 of the rotary damper 13 in the axial direction.

Accordingly, a pulling force P, which is a reaction force of the tensile force F, is generated at the connection point e between the axle housing 4 and the link 15 along the axial direction of the link 15, and the pulling force P Of the vehicle body 3 acts as an extension-side generated damping force R for attenuating the vertical vibration of the vehicle body 3, and the compliance control force Q, which is a longitudinal component, pulls the axle housing 4 rearward.

Therefore, similarly to the above case, the axle housing 4 is connected to the upper link 6 by the compliance control force Q having a magnitude corresponding to the operating angle θ of the link 15 and the extension-side generated damping force R of the rotary damper 13. Lower link 7
The rubber bushings 8 to 11 interposed with respect to the respective connecting portions are operated while being deformed in a direction opposite to the direction outside the turning direction, to steer the rear wheel 1 toward the toe-out side.

As described above, the compliance control force Q acting on the outer and inner axle housings 4 in the turning direction in the front-rear direction is determined by the pressure-side or extension-side generated damping force R of the rotary damper 13 and the operating angle θ of the link 15. The direction and size are set.

Accordingly, even if the rotary dampers 13 have the same length and the same damping force characteristics,
For example, as shown in FIG. 5, if the length of the link 15 is increased and the mounting point of the rotary damper 13 is moved upward accordingly, the operating angle θ of the link 15 with respect to the same operating angle of the rotary damper 13 decreases. As a result, the compliance control force Q decreases.

Conversely, as shown in FIG.
While reducing the length of the rotary damper 1
By moving the mounting point 3 downward, the operating angle θ of the link 15 with respect to the same operating angle of the rotary damper 13 increases, and the compliance control force Q increases.

Therefore, the vertical vibration damping action of the vehicle body 3 is set by selecting the compression-side and extension-side generated damping force characteristics of the rotary damper 13, and the compliance control force Q
Is the link 1 including the arm 14 of the rotary damper 13.
By changing the length of the rotary damper 5 and moving the mounting point of the rotary damper 13 in accordance with the change, the respective settings can be made independently.

In this manner, the steering operation (4WS effect) of the front and rear wheels is exerted at the time of steering such as a lane change without deteriorating the original vibration damping function of the rotary damper 13, so that the vehicle can run stably while preventing the car's swinging phenomenon. Not only secure
In response to rolling of the vehicle body on rough roads, the rear wheels are automatically controlled toe-in and toe-out to ensure running stability.

In the above embodiment, the case where the rotary damper 13 is disposed on the rear side of the axle housing 4 has been described. However, the link 15 is provided within the entire operating angle range of the arm 14 of the rotary damper 13. If you lay out so that it always keeps backwards,
Connection point e between axle housing 4 and link 15 and connection point f between arm 14 and link 15 of rotary damper 13
Is completely the same as in the above embodiment.

Therefore, by adopting such a layout, it is possible to arrange the rotary damper 13 in front of the axle housing 4 as shown in FIG.

Although not shown, even if the connecting point e between the axle housing 4 and the link 15 is moved to the upper link 6 or the lower link 7 which is the unsprung rear wheel support mechanism including the axle housing 4. Since the compliance control force Q acts on the axle housing 4 through the upper link 6 or the lower link 7, it is apparent that the same control operation can be performed.

Further, the rear wheel supporting mechanism is not limited to the double trailing type rear wheel suspension device of the above embodiment, but may be applied to other rear wheel suspension devices such as a swing axle type and a wishbone type. It is needless to say that can be applied.

[0051]

As described above, according to the first aspect of the present invention, the vertical vibration damping action and the compliance control action of the vehicle body can be set independently of each other, so that an ideal damper and compliance steer are configured. can do.

Thus, the steering operation (4WS effect) of the front and rear wheels can be exerted at the time of steering such as a lane change without deteriorating the original damping action of the rotary damper, and the vehicle can run stably while preventing the car's swinging phenomenon. Not only can we secure it,
In response to rolling of the vehicle body on a rough road, the rear wheels are automatically controlled toe-in and toe-out in accordance with the rolling, thereby ensuring running stability.

[0053]

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment in which the present invention is applied to a double trailing link type rear wheel suspension device.

FIG. 2 is a plan view of the same.

FIG. 3 is an explanatory diagram showing a force relationship of each part at the time of a pressure side operation.

FIG. 4 is an explanatory diagram showing a force relationship of each part during the extension side operation.

FIG. 5 is an explanatory view illustrating a means for changing a compliance control force.

FIG. 6 is an explanatory view illustrating a means for changing a compliance control force.

FIG. 7 is a side view showing another embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 rear wheel 3 vehicle body 4 axle housing 13 rotary damper 14 arm 15 link

Claims (1)

(57) [Claims] 1. A rear wheel suspension device having a compliance function for automatically turning a rear wheel to a toe-in or toe-out side in response to a direction of a force applied to the axle in the front-rear direction. A rotary damper is used as a shock absorber that attenuates the vertical vibration. The body on the sprung side and the rear wheel support mechanism on the unsprung side are connected to each other via an arm of the rotary damper and a link connected to the arm. A rear wheel suspension device for a vehicle, wherein the rear wheel suspension device is arranged so as to always maintain a backward inclination within an entire operating angle range of an arm in a rotary damper.