JPS63121513A - Rear suspension unit - Google Patents

Abstract

PURPOSE:To improve the driving stability of a vehicle by arranging a rear suspension unit for the vehicle so that the wheel toe angle variations of the two links constituting an upper link will be the same when the force in the vehicle longitudinal direction is inputted from the grounding point and when it is inputted from a rear drive shaft. CONSTITUTION:It is assumed that a straight lines for connecting an intersection point A of the extension lines from respective center lines of upper links 21 and 22 to a pivoting center point B on the outer side end 10b of the A arm 10 of a lower link assembly is a virtual king pin axis D. The upper links 21 and 22 are arranged so that the virtual king pin axis D will be off-set by x to the outside of a vehicle body on the wheel center line and by y to the inside of the vehicle body on the road surface. Depending on the selection of the offset amount of x and y and the inclining degree of the king pin axis, D, the compliance rigidity is made to be same when a foot brake is applied and an engine brake is actuated. In this manner, the driving stability of the vehicle can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a rear suspension for a vehicle.

(Prior Art) This type of rear suspension device is known, for example, as disclosed in Japanese Patent Application No. 60-289327 previously filed by the present applicant. This is a double wishbone type rear suspension consisting of an upper arm, a lower arm, and a lateral link.In particular, the upper link system is composed of two wooden links, and by arranging it at a specific position, the virtual kingpin axis passes through the wheel center.

(Problem to be Solved by the Invention) However, in such a conventional rear suspension, there is a force in the longitudinal direction that acts on the grounding point of the tire during foot braking, and a force in the longitudinal direction that acts on the wheel center during engine braking. The toe angle displacement of the tire caused by the force is different.

Therefore, when braking while a vehicle is turning, if you release the accelerator to apply the engine brake and press the brake pedal to apply the foot brake in succession, the vehicle's behavior will differ due to each brake operation. As a result, there was a problem in that the stability of vehicle handling was reduced.

In other words, in the embodiment of Japanese Patent Application No. 60-289327, although a large toe-in displacement occurs in the tire due to the longitudinal force acting on the grounding point of the tire during foot braking, the Depending on the longitudinal force acting on the wheel center, only a slight toe-in displacement occurs in the tire. Therefore, there is a problem in that when the foot brake and engine brake are applied continuously while the vehicle is turning, the behavior of the vehicle changes and the steering stability deteriorates.

(Means for Solving the Problems) In order to solve the above problems, in the present invention, one end is swingably connected to the vehicle body via an elastic bushing, and the other end is connected to the axle side member. The wheel is supported by an upper link system and a lower link system, and a lateral rod arranged in the vehicle width direction at a position behind the axle, and the upper link system is mounted on the vehicle body side so that the distance between the mounting points on the axle side is The lower link system is composed of two links whose distance is smaller than the distance between the points, and the lower link system has a Δ
In a rear suspension with a molded arm, the force applied in the longitudinal direction of the vehicle to the two links that make up the upper link system is approximately the same when applied manually from the tire grounding point and when applied manually from the rear drive shaft. A rear suspension device is constructed by arranging the rear suspension device at a position where a wheel toe angle displacement can be obtained.

(Function) As described above, in the present invention, in addition to the conventional rear suspension described above, two parts constituting the upper link system are added.
This link is placed at a position where approximately the same wheel toe angle displacement is obtained when the force in the longitudinal direction of the vehicle is input from the tire grounding point and when it is input from the rear drive shaft. In moderate situations, the behavior of the vehicle does not change even if the foot brake and engine brake are applied continuously. Therefore, according to the present invention, it is possible to further improve the handling stability of a vehicle having this type of rear suspension.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

In the figure, 1 is a suspension support member attached to the vehicle body, 2 is a propeller shaft, 3 is a differential gear, 4 (see FIG. 2) is a rear drive shaft, 5 is a rear axle, and 6 is a rear wheel. 7 is an axle housing that rotatably supports the rear axle 5, 8 (see Fig. 3) is a brake mounting plate fixed to the housing 7, and 10 is an A-type arm, the leg ends 10a of which are shown in Fig. 4. A pivot shaft 12 is supported via an elastic bushing 11 as shown.
is attached to the support member 1 of the rear suspension via the bracket 13. Also, the free end 1 of the A-type arm lO
0b is connected to the end of the bracket 14 projecting downward from the housing 7 via a spherical joint (not shown). Note that 15 is a dust cover. Reference numeral 16 indicates a bracket protruding from the rear of the axle housing 7, and reference numeral 17 indicates a lateral loft, the inner end 17a of which is connected to the rear of the differential gear 3 via the elastic pusher 511, the pivot shaft 12 and the bracket 13 as in FIG. It is attached to the support member 1 of the rear suspension. The outer end 17b of the lateral rod 17 is connected to the rear end of the bracket 16 via a spherical joint as described above.

Note that 18 is a shock absorber, and 19 is a torsion bar.

In this embodiment, a bracket 20 is provided to protrude upward from the axle housing 7, and the upper end of this bracket 20 is further branched back and forth to form a front end 20a and a rear end 20a.
b, and connects the front end 20a and the outer end 21b of the link 21 via a ball joint (not shown), and connects the inner end 21a of the link 21 with an elastic pusher as in FIG. A pivot shaft 12 supported via a bracket 11 is attached to the vehicle body via a bracket 13. Also, the rear end 20b of the bracket 20 is connected to the outer end 22b of the link 22 via the same ball joint, and
The inner end 22a of this link 22 is connected to the elastic bushing 1.
The pivot shaft 12 supported through the A-type arm IO is attached to the vehicle body through the Brakef 13, and these links 21 and 22 constitute an upper link system, and the A-type arm IO constitutes a lower link system.

As shown in FIG. 5, the upper links 21, 2
For the distance (span) L between the vehicle body side (inside) attachment points 21a and 22a of 2, the axle side (outside) attachment points 21b and 22
In addition to reducing the distance between b and i, the two links 21 and 22 that make up this upper link system are subjected to force in the longitudinal direction of the vehicle that is applied manually from the tire contact point T and when input from the rear drive shaft 4. The wheel is placed at a position where approximately the same wheel toe angle displacement can be obtained in both cases.

That is, in this embodiment, as shown in FIGS. 2 and 5, the intersection point on the extension line of each center line of the links 21 and 22 is designated as A, and the intersection point of the outer end portion 10b of the A arm 10, which is the lower link system, is designated as A. The pivot center point is B, and the center point of the rear wheel 6 is C.
Then, the straight line connecting points A and B becomes the virtual kingpin axis.

In this embodiment, as shown in FIG. Inward (positive direction) y
offset (second kingpin offset).

Next, the present invention will be explained in detail. As shown in Figure 6,
When the lower link system is composed of the A-arm 10 that is swingably attached to the vehicle body via an elastic bushing and the lateral rod 17, the lower ball joint at the outer end 10b of the A-arm 10 is affected by braking force, etc. Due to the application of the longitudinal force f, the toe angle of the rear wheel 6 changes by α.

The toe-in amount α corresponds to the magnitude of the longitudinal force f that is applied manually to the lower ball joint 10b, but in terms of braking, the magnitude of the longitudinal force f corresponds to the amount of human force applied to the wheel center during engine braking. The longitudinal force Fa input to the tire grounding point T during foot braking has a larger value than the longitudinal force Fill. Next, the reason will be explained.

In FIGS. 7(a) and (c), 6 is the tire, A is the outer virtual pivot point of the upper link system, B is the outer pivot point of the lower link system, C is the center of rotation of the tire 6, and F is the lateral rod 17. , E is the road surface, and T is the grounding point of the tire 6.

As shown in Aiki 7 (a), when the foot brake force Fa is input from the road surface E, a force f acts on the pivot point of the upper link system, and a force r acts on the pivot point B of the lower link system.
The power of 2 is human power.

Due to the balance of forces, 1pal=lf+l+1fzl ---(i) Due to the balance of moments, If, hl l = I f2h21 --- (2
).

Furthermore, as shown in Fig. 7(b), during engine braking F
b is input to the rotation center C of the tire 6. Therefore, a component force of f3 acts on the pivot point A, and a component force of f acts on the pivot point B.

Due to the balance of forces, 1Fbl=l et al + l f, l ---(3)
Due to the balance of moments, 1f3131=lf, 6.1---(4).

In equations (1) to (4), if we solve the relationship between r2 and f4 after assuming that Fa=Fb, we find that f2>f4, and the lower link system is stronger during foot braking than during engine braking. It can be seen that the longitudinal force acting on the pivot point becomes large, and as a result, the displacement toward the toe-in side shown in FIG. 6 becomes large.

As mentioned above, the amount of toe-in α (see Figure 6) that occurs when longitudinal force is applied manually to pivot point B of the lower link system is:
It is small during engine braking and large when foot braking.

Next, as shown in Fig. 2, the first kingpin offset X (negative) on the wheel center line C and the second kingpin offset
A change in the toe angle α (see FIG. 6) of the wheel 6 caused by the king pin offset y (positive) will be explained.

When Fb is input during engine braking to wheel center 〇, the resulting toe-in generation moment Mb is Mb = Fbx x --- (5) When foot brake force Fa is input from road surface E, the resulting toe-out generation moment is Ma becomes: Ma=FaXy---(6). Now let Fa = Fb, and from Figure 2 lxl < IYl
Then, 1Mal>1Mbl.

That is, by providing a negative first king pin offset X, a small toe-in generation moment Mb is generated during engine braking, and by providing a positive second king pin offset y, a toe-out generation moment Ma is generated during foot braking. can be caused.

The above relationships are summarized in the following table.

In other words, the above settings increase the amount of toe-in generated during engine braking and decrease the amount of toe-in generated during foot braking, as disclosed in Japanese Patent Application No. 60-289327, and the total difference between engine braking and foot braking is reduced. Two upper links are arranged so that the same toe change occurs.

FIG. 8 shows the relationship between the kingpin axis and compliance steer rigidity. The ordinate has a numerical value indicating the compliance steer stiffness (unit: deg/100 kg), that is, the ratio of the amount of change in toe-in to the longitudinal force.

Also, on the abscissa, the unit of kingpin inclination (unit: deg. ), the first king pin offset amount X (unit: mm), and the second king pin offset) I
A numerical value indicating y (unit: fflff1) is attached.

In FIG. 2, the king pin inclination angle is shown with a clockwise angle relative to the vertical axis as positive and a counterclockwise angle as negative.

The first kingpin offset amount X1 and the second kingpin offset amount y are defined as positive on the inside of the vehicle body of a vertical line passing through the center point C of the tire 6, and negative on the outside.

Curve P in the figure represents the characteristics when longitudinal force is applied manually to the contact point T, that is, during foot braking, and curve Q represents the characteristics when longitudinal force is applied manually to the wheel center 〇, that is, during engine braking. There is.

According to this FIG. 8, the first king pin offset amount is
-55+on+, the second king pin offset amount is 23
0 mm and the king pin inclination angle is 148 degrees,
It can be seen that the compliance steer stiffness is the same during foot braking and engine braking.

That is, by setting the rear suspension to the above-mentioned values, the change in toe angle can be made the same both during engine braking and during foot braking. In the present invention, the rear suspension is set as described above.

In the above embodiment, the first kingpin offset amount is negative and the second kingpin offset amount is positive, but the present invention is not limited to this. That is, depending on the determination of the position of point B in FIG. 2, the second kingpin offset amount can be made positive and the first kingpin offset amount can be made zero or positive. In any case, according to the present invention, the two links of the upper link system may be arranged so that the change in toe angle caused by the foot brake or engine brake is approximately the same. .

(Effects of the Invention) As described above, in the present invention, in the conventional rear suspension described above, two
This is because the book links 21 and 22 are placed at positions where approximately the same wheel toe angle displacement can be obtained when the force in the longitudinal direction of the vehicle is applied manually from the tire grounding point and when it is input from the rear drive shaft 4. When the vehicle is turning, the behavior of the vehicle does not change even if the foot brake and the engine brake are applied continuously. Therefore, according to the present invention, an excellent effect can be obtained in that the steering stability of a vehicle having this type of rear suspension can be further improved.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing an embodiment of the device of the present invention, Fig. 2 is a rear view, Fig. 3 is a side view of the same, Fig. 4 is a partial sectional view, and Fig. 5 is an A-type arm of the device of the present invention. and a plan view showing the arrangement of each link, Fig. 6 is an explanatory diagram of the operation of the device of the present invention, Fig. 7 (a) and (b) are explanatory diagrams of the principle of the present invention, and Fig. 8 is a diagram of the kingpin shaft and compliance steer rigidity. FIG. ■...Rear suspension support member 5...Rear axle 6...Rear wheel 7...Axle housing 10...Δ type arm 14.16...Bracket 17...Lateral rod 18...・Shock absorber 19...Torsion bar 20...Bracket 21.22...Link patent applicant Nissan Motor Co., Ltd. Representative Patent Attorney Akatsuki Sugimura Competence
Written by patent attorney Oki Sugimura No. 5
Figure 6

Claims (1)

[Claims] 1. An upper link system and a lower link system, one end of which is swingably connected to the vehicle body via an elastic bush, and the other end of which is connected to an axle-side member; The wheels are supported by disposed lateral rods, and the upper link system is composed of two links whose distance between attachment points on the axle side is smaller than the distance between attachment points on the vehicle body side, and the lower link system In a rear suspension with an A-type arm whose apex is the attachment point on the axle side, when a force in the longitudinal direction of the vehicle is input from the tire grounding point to the two links forming the upper link system,
A rear suspension device characterized in that the rear suspension device is arranged at a position where substantially the same wheel toe angle displacement can be obtained when input is input from a rear drive shaft.