JPH019686Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to a rear suspension of an automobile.

(Prior Art) One type of automobile rear suspension is a trailing arm type. This type of suspension, in which the front end of the trailing arm is pivotally connected to the vehicle body via a rubber bushing, is generally known as disclosed in, for example, Japanese Utility Model Application No. 56-62205.

By the way, when an automobile accelerates, such as when starting, a scoot phenomenon occurs in which the vehicle body tilts backwards downwards (frontward upwards). This phenomenon occurs not only due to inertial force but also due to the arrangement of the trailing arm, and there have been proposals to obtain an anti-scott effect by changing the height of the trailing arm or the direction of its swing axis. . However, changing the arrangement of the trailing arm may affect the roll center height, toe change, etc., and may impair running stability.

(Purpose of the invention) The present invention was developed to provide a rear suspension for automobiles in which the front end of the trailing arm connects to the vehicle body with a rubber bushing. The aim is to obtain an anti-scott effect.

(Structure of the invention) The rear suspension for an automobile according to the invention includes a rear wheel support that supports a rear wheel, and a trailing arm that supports the rear wheel support, and the connecting portion between the front end of the trailing arm and the vehicle body is It is made up of rubber bushings. This rubber bush has a small spring constant in the diagonally upward direction to the front of the vehicle, and a large spring constant in the direction perpendicular to this, so that the trailing arm moves forward due to the driving force that acts forward on the rear wheel center during acceleration. Use the pushing force to move the front end of the trailing arm upwards,
This is an attempt to obtain an anti-scotto effect.

(Embodiment) FIGS. 1 to 3 each show the overall configuration of a rear suspension of an automobile. A rear wheel 1 is rotatably supported by a rear wheel support 2. The rear wheel support 2 is supported by a side frame 7 and a cross member 8 of the vehicle body by a trailing arm 3 and three lateral links 4, 5, and 6. Furthermore, a strut 10 is interposed between the rear wheel support 2 and the suspension tower 9.

The trailing arm 3 is a thin plate that is arranged long in the front-rear direction with the plate surface in the vertical direction, and is connected to the side frame 7 at one point at the front end so as to be vertically swingable, and supports the rear wheel support 2 at the rear end. ing. A connecting portion at the front end of the trailing arm 3 is composed of a rubber bush 11. The shaft portion of the rubber bush 11 is supported by a bracket 12 fixed to the lower surface of the side frame 7.

On the other hand, the three lateral links are composed of a first lateral link 4, a second lateral link 5, arranged above and below, and a third lateral link 6, arranged on the front side. ing. The first lateral link 4 provided on the upper side is connected at its outer end to the rear upper position of the rear wheel support 2 and at its inner end to the upper position of the cross member 8 so as to be vertically swingable. The second lateral link 5 provided on the lower side has an outer end connected to a lower rear position of the rear wheel support 2 and an inner end connected to a lower position of the cross member 8 so as to be vertically swingable. Furthermore, the third lateral link 6 provided on the front side is shorter than the first and second lateral links 4 and 5, and has an outer end located below the front of the rear wheel support 2 and an inner end located forward of the cross member 8. They are respectively connected to brackets 13 of the extending side frames 7.

In other words, the three lateral links 4 to 6 have their outer ends connected to three points on the rear wheel support 2 that form the vertices of a triangle that are spaced apart from each other, and their inner ends that connect to three points on the vehicle body that form the vertices of a triangle that are spaced apart from each other. has been done. In this example, three lateral links 4~
Each of the outer end connecting portions 14 to 16 and each of the inner end connecting portions 17 to 19 of 6 is constituted by a rubber bush.

Therefore, the rubber bush 1 that constitutes the connecting portion between the trailing arm 3 and the side frame 7
The specific structure of No. 1 is shown in FIG. In the figure, 20 is an outer cylinder, 21 is an inner cylinder, and 22 is an outer cylinder 2.
0 and the inner cylinder 21, and the rubber part 22 has cavities 23, 23 formed at the front lower position and rear upper position of the inner cylinder 21, respectively.
Arc-shaped metal plates 24, 24 are buried in the front lower position and the rear lower position of 1, respectively.

Therefore, the spring constant of the rubber bush 11 is small in the A direction connecting the diagonally lower front and upper rear of the vehicle body because the cavity 23 collapses under the load and the amount of strain becomes large; In direction B, which is perpendicular to the direction B, since the cross-sectional area occupied by the rubber portion 22 is reduced by the metal plates 24, 24, the amount of strain is small, and the spring constant in the direction B is large. Note that the angle of inclination of the A direction with respect to the horizontal line is preferably about 30 to 45 degrees, for example.

Next, to explain the function of the rear suspension, first, the geometrical interference between the trailing arm 3 and the lateral links 4 to 6 caused by the vertical movement of the rear wheel 1 is caused by the thin plate-like trailing arm 3. It is absorbed by the deformation of each rubber bush.

In addition, looking at the camber change and toe change accompanying the vertical movement of the rear wheel 1, the first lateral link 4 and the second and third lateral links 5 and 6 arranged above and below have a large ground camber change. In addition to preventing this, desired camber control can be performed by appropriately setting the length of each lateral link 4 to 6. on the other hand,
Regarding toe change, in the case of this embodiment, the third lateral link 6 on the front side restricts the change to the toe-out side when bumping, and also due to the influence of compliance steering, the rear wheel 1 changes to the toe-in side when bumping. However, when rebounding, it changes to the toe-out side.

When the rear wheel 1 rides on a protrusion on the road surface, the rubber bush 11 receives a force in the longitudinal direction of the vehicle body, but since the spring constant in the diagonal direction A in FIG. 4 is small, the horizontal component of this diagonal direction A is The front and rear compliance is large, and the rubber bush 11 is flexibly deformed to prevent large impacts from being transmitted to the vehicle body.

Next, if we look at the action of the rear suspension during acceleration such as when starting, as shown in Fig. 5, the driving force F acts forward at the center S of the rear wheel 1, and the driving torque reaction force directly acts on the spring. (because the differential is installed on the car body). At this time, since the rubber bush 11 has a small spring constant in the diagonal direction A, the outer cylinder 20 moves diagonally forward and upward in response to the force toward the front of the vehicle body, and the center of the outer cylinder 20 is at the height when running at a constant speed. Lifts from position H ₀ to height H. Note that the horizontal distance L from the wheel center S hardly changes (it becomes slightly shorter).

Therefore, if we consider the downward urging force R of the rear wheel 1 due to the driving force F, the trailing arm 3 will have a moment of (H-h) x F (h is the height of the wheel center S from the road surface 25). ) is loaded, so R=(H-h)×F/L. During acceleration, the automobile receives a force in the downward direction (the vehicle body moves backward), but the biasing force R reduces the force in the downward direction. In other words, an anti-scott effect corresponding to the biasing force R occurs. Now, considering the biasing force R ₀ when there is no change in the position of the outer cylinder 20 of the rubber bush 11 during acceleration, R ₀ = (H ₀ - h) x F/L, but since H > H ₀ . , R>R ₀ , and as the outer cylinder 20 of the rubber bush 11 moves obliquely forward and upward during acceleration, the biasing force increases and the anti-scott effect increases.

By the way, it is possible to obtain a large anti-scott effect by setting the position of the rubber bush 11 at the height H from the beginning, but in that case, the rear wheel movement caused by the swinging of the trailing arm during normal driving may be reduced. The locus may adversely affect the roll center height, toe change, etc., resulting in a loss of running stability.

In the above embodiment, the spring characteristics of the rubber bush 11 are set by both the cavity 23 and the metal plate 24, but the setting means may be used, such as setting only by one of them.

Moreover, other connecting means such as ball joints may be applied to the connecting portions 14 to 19 at both the inner and outer ends of the three lateral links 4 to 6 in addition to rubber bushings.

The strut may be attached directly to the rear wheel support, or may be connected to the trailing arm or any of the three lateral links.

The rear wheel can also be used as a driving wheel by having a drive shaft passing through the rear wheel support.

(Effects of the invention) According to the invention, the characteristics of the rubber bush at the front end of the trailing arm are such that the spring constant in the diagonally upward direction of the front of the vehicle body is small. This reduces the impact transmitted to the vehicle body due to longitudinal forces, and the posture of the vehicle body does not change much during acceleration, improving ride comfort.

[Brief explanation of the drawing]

Figures 1 to 3 show the rear suspension of an automobile. Figure 1 is a plan view with the strut omitted, Figure 2 is a rear view, Figure 3 is a side view, and Figure 4 is a rubber bushing at the front end of the trailing arm. A cross-sectional view of
FIG. 5 is a schematic side view of the rear suspension for explaining the anti-scott effect. DESCRIPTION OF SYMBOLS 1... Rear wheel, 2... Rear wheel support, 3... Trailing arm, 4... First lateral link, 5... Second lateral link, 6... Third lateral link, 7... Side frame, 8... Cross member, 11... Rubber button.

Claims (1)

[Scope of utility model registration request] It is equipped with a rear wheel support that supports the rear wheel, and a trailing arm that is vertically swingably connected to the vehicle body at one point on the front end and supports the rear wheel support at the rear end. A rear suspension for an automobile, characterized in that the rubber bush has a small spring constant in a diagonally upward front direction of the vehicle body, and a large spring constant in a direction perpendicular to the diagonally upward front direction of the vehicle body.