JPH01247206A - Rear suspension - Google Patents

Abstract

PURPOSE:To enable smooth turning in the rear wheel suspension device of a rear-wheel-drive vehicle by installing the body side of a lateral link on the upper portion of the oscillation center of a final reduction gear and setting the roll steer quantity of a rear wheel larger than a compliance steer quantity. CONSTITUTION:A lateral link 10 is installed in between a lower arm provided right behind the inflection point (a) of the wheel side joint portion 6a of a fixed-length equal-speed joint 6 and an arm 9 provided in the upper position of an oscillation center right behind the differential side joint portion 6b of the fixed-length equal-speed joint 6. The distance between both end shafts of the lateral link 10 is made nearly agree with the distance between the inflection point (a) and oscillation point of the fixed-length equal-speed joint 6. The roll steer quantity of a rear tire at the time of steady turn traveling is set larger than a compliance steer quantity. By this structure, the toe of a rear wheel is changed with vehicle speed enabling smooth turning.

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a rear suspension for a vehicle that drives a rear wheel, and particularly to a rear suspension that automatically changes the toe angle of the wheel when turning.

<Prior art> In the rear suspension installed on a vehicle, when the vehicle is turning, a lateral force is applied toward the center of the turn, especially on wheels outside the center of the turn. It is common practice to always change the toe-in inward to prevent oversteer and improve driving stability.

This tendency is similar to multi-link suspensions, which have been adopted in recent years because they have a simple structure, high space efficiency, light weight, and good characteristics as a rear suspension. Can be seen.

In other words, the technology disclosed in Japanese Patent Publication No. 58-48366 is such that when a rearward load is applied to a wheel support, the rear of the wheel support changes outward from the front of the vehicle when viewed in plan. A wheel support that rotatably supports a rear wheel, two arms that connect the front and rear parts of this wheel support to the inside of the vehicle body and that can swing up and down and back and forth, and the wheel support or A connecting member is provided that elastically connects the arm near the wheel support supporting portion to the vehicle body while allowing a slight movement of the vehicle body in the longitudinal direction, and connects the vehicle body front and back between the wheel support side support points of the two arms. The distance in this direction is smaller than the distance in the longitudinal direction of the vehicle body between the support points on the vehicle body side of these two arms, so that when the wheel support body moves rearward due to a backward load acting on the rear wheel contact point, the wheel support is The rear part of the wheel support body is configured to be displaced outward from the vehicle body when viewed from above the vehicle body with respect to the front part of the vehicle body.

Furthermore, Japanese Patent Laid-Open No. 58-188707 discloses a rear suspension component whose one end is rotatably supported on the vehicle body, and a wheel support member which rotatably supports the wheel, in order to perform toe control of the wheel during turning. and,
a ball joint that connects the wheel support member to the rear suspension component so as to be swingable about one point; and a first elastic bush that connects the wheel support member and the rear suspension component. , a second elastic bushing that connects the wheel support member and the rear suspension component, and the ball joint is located in the fourth quadrant in the horizontal-vertical coordinates of the wheel center as viewed from the left side of the vehicle body. , the first elastic bushing is in the first quadrant of the coordinates, and the second elastic bushing is in the second quadrant of the coordinates.
Techniques located in each quadrant are shown.

<Problems to be Solved by the Invention> It is true that according to the technology described in the above-mentioned Japanese Patent Publication No. 58-48366, when the vehicle turns, the rolling of the vehicle body causes the wheels on the outside of the turning center to move toward the bump side. When this happens, the roll steer becomes toe-in, and the above objective is achieved.

However, when the vehicle is constantly toe-in and understeering as described above when the vehicle is turning, the rudder becomes less effective and the driving feeling becomes sluggish, resulting in poor maneuverability especially at medium and low speeds. Not desirable for a vehicle.

Further, according to the technique described in the above-mentioned Japanese Patent Application Laid-Open No. 58-188707, the rear wheel is toe-in according to the force applied to the wheel depending on the driving condition of the vehicle, that is, lateral force, braking force, engine braking force, and driving force. It is possible to control toe-out, but since the toe change is constant over time regardless of vehicle speed, the driver feels a great deal of discomfort, and the mechanism is complex and expensive.

In view of the above, the present invention provides a rear suspension with a simple structure that allows the rear wheels of a vehicle that drives the rear wheels to smoothly and safely change toe according to the vehicle speed when the vehicle turns, thereby allowing the vehicle to turn smoothly. That is.

<Means for Solving the Problems> In order to achieve the above object, the present invention provides a fixed-length constant velocity joint that swingably connects a final reduction gear mounted on a vehicle body and a rear wheel supported by a rotating support. , and behind the fixed length constant velocity joint, a lateral link having the same length as the fixed length constant velocity joint, one end of which is connected to the rotating support, and the other end of which is connected to the final reduction gear side of the fixed length joint. Each is attached to the vehicle body through an elastic bushing above the center, and
The amount of roll steer of the rear tire during steady turning of the vehicle is made larger than the amount of compliance steer.

<Function> When the vehicle turns, first, a lateral force F toward the turning center is generated at the rear wheel 4 on the outside of the turning center, and after a delay, the rolling of the vehicle body starts.

Because the elastic bushing 11 is used for the rear lateral link 10 of the fixed-length constant velocity joint 6 and the lateral link 10 which also serves as the front lateral link, due to the lateral force F, the elastic bushing 11 is deflected relatively largely, causing so-called compliance steer-out. arise. As a result, the rear wheel 4 toes out as indicated by the second arrow, causing a yaw motion of the vehicle, resulting in a sharp rise at the beginning of the turn.

Next, the rolling of the vehicle body causes so-called roll steer, and as the vehicle body sinks outward, the fixed length constant velocity joint 6 and the lateral link 10 relatively swing upward, and at this time, the fixed length etc. on the front side Since the swing locus of the rear wheel side bending point a of the quick coupling 6 is inside the swing locus of the attachment point (shaft 13) of the elastic bush 11 of the rear lateral link 1o, the rear wheel 4 is toe-in.

Since the toe-in amount is greater than the toe-out amount, the vehicle enters toe-in in a steady turning state, and thereafter the rear wheel 4 continues turning safely with toe-in.

<Example> Examples will be described below with reference to the accompanying drawings.

In the embodiment shown in FIGS. 1 to 3, reference numeral 1 denotes a knuckle constituting a rotational support for the rear wheel, which rotatably supports the rear wheel 4 via an axle 2 and a hub 3, and also has a fixed length as described below. A lower arm portion 5 is provided directly behind the bending point a of the wheel-side joint portion 6a of the quick coupling 6.

A wheel side joint portion 6a of a fixed length constant velocity joint 6 which also serves as a lateral link is connected to the axle 2, and a differential side joint portion 6b of the fixed length constant velocity joint 6 is connected to the vehicle body (not shown) by a support member 7. ) is connected to a final reduction gear (differential device; differential) 8.

On the vehicle rear side of the support member 7 (right side in FIG. 2),
An arm 9 is provided directly behind the differential side joint portion 6b of the fixed length constant velocity joint 6 and above the swing center, and between the tip of the arm 9 and the tip of the lower arm portion 5, A lateral link 10 is swingably spanned by a shaft 12.13 via elastic bushings 11 provided at both ends thereof. Note that the distance between the shafts 12 and 13 at both ends of the lateral link 10 is the same as that of the fixed length constant velocity joint 6.
The distance is approximately the same as the distance between the bending point a and the center of swing.

14 is a trailing link, one end of which is attached to a support portion 15 provided on the lower surface of the knuckle 1, and the other end of which is attached to a supporting portion 15 provided on the lower surface of the knuckle 1;
They are each swingably attached to the vehicle body (not shown) further forward.

Reference numeral 16 denotes a strut spring mechanism integrated with the damper 17, which is formed at the upper end of the knuckle 1 and is attached to the upper arm portion 1.
8 and the vehicle body (not shown) above it,
Therefore, when driving on an uneven road, the wheel 4 bends the strut spring mechanism 16 and the damper 17, and
It rotates up and down about the pivot center of the fixed length constant velocity joint 6 and the shaft 12 of the lateral link 10.

Further, the intersection 21 where the line 20 passing through the bending point a, the axis 13 of the lateral link 10, and the attachment point 19 of the upper end of the strut spring mechanism 16 to the vehicle body contacts the ground is the intersection 22 where the center line of the wheel 4 contacts the ground. The geometry of the rear suspension has been decided so that it is located further inward by L.

In the embodiment configured as described above, when the vehicle turns, a lateral force F toward the turning center is generated at the rear wheel 4 on the outside of the turning center as shown in FIG. Begins.

Due to the lateral force F, the elastic bushing 11 belonging to the lateral link 10 is deflected relatively largely, resulting in so-called compliance steer-out. This causes the rear wheel 4 to toe out as indicated by the second fixed arrow, causing the vehicle to produce a yaw motion, resulting in a sharp rise at the beginning of the vehicle turn.

Next, the rolling of the vehicle body causes so-called roll steer, and as the vehicle body sinks outward, the fixed length constant velocity joint 6 and the lateral link 10 relatively swing upward.
As shown in FIG. 1, the swing locus of the bending point a on the rear wheel 4 side of the fixed length constant velocity joint 6 is inside the swing locus of the shaft 13 of the lateral link 10, so the rear wheel 4 is toe-in.

As will be described later, since the toe-in amount is greater than the toe-out amount, the vehicle is steadily toe-in from then on, and the wheels 3 continue to turn safely while being toe-in.

This state is shown by the solid line in Figure 4, but the actual steer (solid line) obtained by combining compliance steer and roll steer has a relatively large amount of toe-out at low speeds, and a small amount of toe-in compared to the amount of toe-out. (Of course, the absolute value increases the toe-in amount.) However, at high speeds, the toe-in amount becomes much larger than the toe-out amount, and the transition from toe-out to toe-in also occurs as t in the figure becomes t2. It can be expedited. This is because the delay between roll steer and compliance steer becomes smaller at high speeds, T', compared to T at low speeds, that is, the vehicle body rolls faster.

In any case, in the rear suspension of the present invention, the amount of roll steer-in is set to be greater than the amount of compliance steer-out so that the amount of toe-in is greater than the amount of toe-out regardless of whether the vehicle is at low speed or high speed, as shown in FIG.

Furthermore, in a vehicle equipped with the rear suspension of this example,
Since the intersection point 21 is located inside the intersection point 22 during braking, the wheel 4 rotates in the toe-out direction due to the braking force as indicated by the shaded arrow in FIG.

Therefore, as shown in Figure 5, one side of the road surface has an ice burn (
If a vehicle is traveling on a split road where one side is a dry road (high μ) and the other brake is braked,
Since the side rear wheels toe out as described above, it is possible to prevent the vehicle from spinning, which is likely to occur due to the difference in braking force between the left and right wheels.

Additionally, when driving force (in the opposite direction to braking force) is applied, the wheels enter toe-in, which stabilizes the vehicle's posture and allows it to accelerate safely.

<Effects of the Invention> As described above, the present invention provides a structure in which a final reduction gear mounted on a vehicle body and a rear wheel supported by a rotating support are swingably connected by a fixed-length constant-velocity joint, and the fixed-length constant-velocity joint At the rear of the fixed length constant velocity joint, a lateral link of the same length as the fixed length constant velocity joint is connected with one end to the rotating support and the other end elastically connected to the vehicle body above the swing center of the fixed length joint on the final reduction gear side. They are attached via bushings, and the amount of roll steer of the rear tires is made larger than the amount of compliance steer when the vehicle is making steady turns, so the rear wheels are temporarily toeed out at the beginning of the vehicle's turns to sharpen the start-up. This has the effect of improving the effectiveness of the steering wheel and enabling stable high-speed turns as toe-in when entering a steady turn.Also, since the above-mentioned toe change is automatically performed according to the vehicle speed, it does not cause any discomfort to the driver. Furthermore, since the fixed length constant velocity joint is also used as one of the lateral links, the structure is simple, the number of parts is small, and it can be manufactured at low cost.

[Brief explanation of the drawing]

1 to 3 are schematic diagrams showing one embodiment of the rear suspension of the present invention, with FIG. 1 showing a front view, FIG. 2 a plan view, and FIG. 3 a side view. FIG. 4 is an operational diagram of the rear suspension of the present invention, and FIG. 5 is an operational diagram of a vehicle equipped with the rear suspension of the embodiment during braking. 1; Knuckle (rotating support), 2; Axle, 4: Rear wheel, 5; Arm portion, 6; Fixed length constant velocity joint, 8; Final reduction gear, 9; Arm, 1
0; Lateral link; 11; Elastic bushing; 12, 13; Axis 14; Trailing link. 16; Strut spring mechanism; 17; Damper; 21, 22; Intersection. Patent applicant Isuzo Jidosha Co., Ltd. Figure 3

Claims (1)

[Claims] A final reduction gear mounted on the vehicle body and a rear wheel supported by a rotating support are swingably connected by a fixed length constant velocity joint, and a fixed length constant velocity joint having the same length as the fixed length constant velocity joint is connected behind the fixed length constant velocity joint. One end of the lateral link is attached to the rotating support body, and the other end is attached to the vehicle body via an elastic bush above the swing center of the fixed length joint on the final reduction gear side, and the lateral link is attached to the vehicle body through an elastic bushing, and A rear suspension that makes the amount of roll steer of the rear tires greater than the amount of compliance steer when driving.