JP2000177349A - Rear suspension device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rear suspension device which has a great degree of freedom in arrangement and the characteristics of a desirable camber angle change and a toe angle change. SOLUTION: A rear suspension device 1 includes right and left wheel supports 5 mounted to trailing arms 5a extending forwardly to a vehicle, trailing arms 5a being rotationally supported so as to be oscillatable vertically on the body side via an elastic bush 7 and joined to each other with a cross beam 9 extending to the cross direction. The cross beam 9 consists of a central portion 13 and both ends 15, 15 extending to the right and left. A shearing center line (m) connecting the shearing centers (n) of the cross sections of the central portion 13 horizontally extends to the cross direction and center lines (m') of both ends 15, 15 extend slantly backwardly of the vehicle across the center line (m), so that the torsional rigidity of both ends 15, 15 may be set to be lower than the torsional rigidity of the central portion 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called torsion beam type rear suspension device used for an automobile.

[0002]

2. Description of the Related Art A conventional torsion beam type rear suspension device is disclosed in, for example, Japanese Patent Application Laid-Open No. 5-278424.

In such a conventional rear suspension device, for example, shown in FIG. 15B, a wheel support 205 supporting left and right wheels is provided with a trailing arm 2.
05a, the trailing arm 205a
The front end portion 207 is rotatably supported by the vehicle body so as to be vertically swingable, and a torsion beam member 209 is connected between the left and right trailing arms 205a.

The torsion beam member 209 is twisted between the right and left wheels when the vehicle body rolls, and generates a spring reaction force to increase the roll rigidity. As shown by a symbol n in FIG. , There is a point that is the torsion center of the cross section with respect to the torsion input.

The conventional torsion beam member 2
09 was simply set in a straight line, and the shear center line m connecting the shear centers n in each cross section was also straight (FIG. 15B). Further, when the torsion beam member 209 is twisted by the roll of the vehicle body, the intersection of the shear center line m and the vehicle center cross section (vertical plane) is the fixed point P during twist deformation (the center point of the twist deformation). Was.

Accordingly, the left and right wheel supports 205
Each of the fixed point P and the trailing arm 205a
Make a rotation about an axis A connecting the support point center 207a of the front end portion 207 with the support point center 207a.

[0007]

When the torsion beam 209 is linear, the shear center line m is near the torsion beam member 209 and the fixed point P is located near the torsion beam member 209. Therefore, the axis A and the shear center line m in FIG.
And the camber angle of the turning outer wheel (e.g., 203L) in the negative direction with respect to the vehicle body becomes large when the vehicle rolls.

As shown in FIG. 17 (rear view), the angle β between the axis A and the shear center line m as viewed from the rear of the vehicle affects the toe angle change characteristic of the turning outer wheel 203L when the vehicle rolls. When the axis A is lowered outward, the turning outer wheel 203L side (the wheel on the body bound side) changes the toe angle in the toe-in direction (roll understeer), and the axis A
Is raised outward, the turning outer wheel 203L side changes toe angle in the toe-out direction (rollover steer).

On the other hand, conventionally, the camber angle change characteristic and the toe angle change characteristic of the suspension have been adjusted by adjusting the cross-sectional shape and the cross-sectional direction of the torsion beam member 209.

However, even if the position of the fixed point P is arranged away from the torsion beam member 209 by adjusting the cross-sectional shape and direction, the torsion beam member
9 has a limit because it is linear, and it is difficult to obtain desirable camber angle change characteristics and toe angle change characteristics.

Further, as shown in FIG. 18 (in plan view), a torsion beam member 209 is provided near the suspension device.
There is a fuel tank 211 and a spare tire storage unit 213 that regulate the arrangement of the camber angle, so that it is more difficult to set desirable camber angle change characteristics.

As shown in FIG. 19 (a side view from the vehicle center side), a vehicle body floor and a vehicle body side member 21 are provided.
In the case of a vehicle aiming to secure a large cabin and luggage space by arranging the fixed point 5 low, there is a restriction on the layout between the vehicle and the suspension, and the position of the fixed point P is set as shown in FIG. A point P 'on the axis A' (a point at which a desired camber angle change characteristic is obtained) or a point P 'on the axis A "in FIG.
It is difficult to arrange the points (points at which desired toe angle change characteristics are obtained).

On the other hand, Japanese Patent Application Laid-Open No. 8-324218 discloses a structure in which a torsion beam member is formed by a member having a curved portion. However, the rigidity of the torsion beam member near a connection point between the torsion beam member and the trailing arm is disclosed. As described above, the torsion center of the entire torsion beam member substantially coincides with the fixed point P, and the above problem has not been solved.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a rear suspension device which has a large degree of freedom in arrangement and can obtain desirable camber angle change characteristics and toe angle change characteristics.

[0015]

In order to solve the above-mentioned problems, the invention according to claim 1 is characterized in that left and right wheel supports for supporting wheels are attached to suspension arms extending forward of the vehicle, respectively. A rear suspension device in which a front end of an arm is rotatably supported on the vehicle body side so as to be able to swing up and down, and the left and right wheel supports or suspension arms are connected by a torsion beam member extending in the vehicle lateral direction and allowing torsional deformation. The torsion beam member includes a lateral portion and both ends extending on both sides of the lateral portion, and a shear center line connecting the shear centers of the cross sections extends substantially horizontally in the lateral portion, and at both ends. The torsion stiffness at both ends is set to be lower than the torsional stiffness at the lateral portion. The features.

According to a second aspect of the present invention, there is provided the rear suspension device according to the first aspect, wherein the shear center lines of the both ends intersect with the shear center lines of the lateral portion in plan view of the vehicle. Is set.

According to a third aspect of the present invention, there is provided the rear suspension device according to the first or second aspect, wherein the shear center lines of the both end portions are aligned with the shear center lines of the lateral portion in a rear view of the vehicle. It is characterized by being set to intersect.

According to a fourth aspect of the present invention, there is provided the rear suspension device according to the third aspect, wherein the shear center lines at the both end portions are lower than the shear center lines at the lateral portions in a rear view of the vehicle. It is characterized by being set to extend inclining.

According to a fifth aspect of the present invention, there is provided the rear suspension device according to any one of the first to fourth aspects, wherein the both ends are connected to the torsion beam member and the wheel support or the suspension arm. It is characterized by being provided in the vicinity.

According to a sixth aspect of the present invention, there is provided the rear suspension device according to the fifth aspect, wherein the both ends are formed in an open cross section, and the lateral portions are formed in a closed cross section. .

According to a seventh aspect of the present invention, in the rear suspension device according to the fifth aspect, the both ends have a shear center line at a position separated in one direction from the centroid of each cross section. The shear center lines of the lateral portion and the both end portions are characterized by being in the same plane.

An eighth aspect of the present invention is the rear suspension device according to the fifth aspect, wherein the both end portions have a continuously twisted cross-sectional shape.

[0023]

According to the first aspect of the invention, the torsional displacement generated in the torsion beam member when the vehicle body rolls is:
The torsional displacement that rotates around the shear center line in the lateral direction of the vehicle and the torsional displacement that rotates around the shear center line that extends crossing the transverse center line of the vehicle can be considered. The torsional center position of the torsion beam member in the vehicle center section at the displacement is obtained as the intersection between the vehicle center section and the respective shear center lines, and the intersection with the shear center lines at both ends is the intersection with the transverse shear center line. It is located at a greater distance from the torsion beam member.

Since most of the torsional displacement occurs at both ends where the torsional rigidity is relatively low, the torsional center position (fixed point position) of the entire torsion beam member in the cross section of the vehicle center is defined by the shear center lines at both ends. In the vicinity of the intersection of the torsion beam members. Therefore, unlike the conventional example,
The angle α (FIG. 16) in a plan view of the vehicle can be set small, and the entire torsion center position is located at a position further away from the torsion beam member upward (FIG. 19).
It is easy to set the desired camber angle change characteristics and toe angle change characteristics.

According to the second aspect of the present invention, the first aspect is provided.
In addition to the effect of the invention, the angle α can be set to be small in a plan view of the vehicle, so that the fixed point can be arranged far away from the torsion beam member, and the camber angle change of the turning outer wheel with respect to the vehicle body negative direction when the vehicle body rolls. Can be kept small.

According to the invention described in claim 3, according to claim 1
Alternatively, in addition to the effect of the second aspect, the fixed point can be disposed largely vertically apart from the torsion beam member. Therefore, the line connecting the fixed point and the front end of the suspension arm when viewed from the rear of the vehicle can be set outward or upward, so that when the body rolls, the change in toe angle of the turning outer wheel is set to the toe-in direction or toe-out direction, and the roll understeer characteristic is obtained. Alternatively, a rollover characteristic can be obtained.

According to the invention described in claim 4, according to claim 3,
In addition to the effects of the invention, the fixed point can be arranged at a large distance upward from the torsion beam member, so that the line connecting the fixed point and the front end of the suspension arm can be set outward, and the vehicle turns when the vehicle rolls. The change in the toe angle of the outer ring is set to the toe-in direction, so that roll understeer characteristics can be obtained.

According to the fifth aspect of the present invention, the first aspect is provided.
In addition to the effects of any one of the inventions of (1) to (4), both ends having low torsional rigidity are provided near the joint between the wheel support or suspension arm and the torsion beam member, so that the fixed point is located far away from the torsion beam member. And a more reliable effect can be obtained.

According to the invention described in claim 6, according to claim 5,
In addition to the effect of the invention, the difference in torsional rigidity between the both ends and the lateral direction can be reliably set.

[0030] According to the invention described in claim 7, according to claim 5 of the present invention.
In addition to the effect of the invention of the present invention, the transverse center and the shear center lines of both ends of the torsion beam member are present on the same plane, and the horizontal, vertical, and oblique arrangement of the fixed point with respect to the torsion beam member is facilitated, Layout flexibility can be expanded.

According to the invention of claim 8, according to claim 5,
In addition to the effects of the invention, it is possible to set the fixed point position at a position largely separated from the torsion beam member by twisting the both ends, so that a more reliable and highly flexible effect can be obtained.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a plan view and a partial cross-sectional view schematically illustrating the configuration of a rear suspension device 1 according to the present embodiment. The upper part of the figure is the front of the vehicle. Figure 2
FIG. 5 is an explanatory diagram, and the contents of the diagram will be described later. First, the configuration will be described.

As shown in FIG. 1 (a plan view of the rear suspension device 1), wheel supports 5, 5 rotatably supporting the left and right rear wheels 3L, 3R are respectively provided with trailing arms (suspension arms) extending forward of the vehicle body. ) 5a, 5a
Attached to. The front end of the trailing arm 5a is rotatably supported by a vehicle body-side frame member (not shown) via an elastic bush 7 so as to be able to swing up and down, and a cross beam (torsion beam member) 9 extending in the vehicle width direction has left and right trailing arms 5a, 5a. Note that the cross beam 9 may be configured to connect the wheel support 5. A fuel tank 11 is arranged in front of the cross beam 9.

The cross beam 9 has a central portion (lateral portion) 13 extending in the lateral direction of the vehicle body, and both end portions 15, 15 extending on both sides of the central portion 13 and extending obliquely rearward of the vehicle. Are located in And both ends 15, 15
Are connected to the rear ends of the left and right trailing arms 5a, 5a.

As shown in the cross-sectional views of FIG. 1 (cross-sectional views in the front-rear direction of the vehicle at the central portion 13 and both end portions 15 and 15), the central portion 13 of the cross beam 9 has a U-shaped The cross section is closed by joining the reinforcing plate 17, and the cross section of both ends 15, 15 is formed in a U-shaped open cross section in the same direction. The shear center n in the closed section of the central portion 13 exists in the closed section. On the other hand, both ends 1
The shear center n in the open section of No. 5 is located near the front outer side of the section away from the centroid (not shown) of each section,
Distributed in a horizontal plane.

FIG. 2 (in plan view of the cross beam 9) shows a distribution state of a shear center line connecting the shear centers n of the respective cross sections. As shown by the broken line in the figure, in the central portion 13, the shear center line m extends substantially horizontally in the vehicle width direction, and the both end portions 15,
The center line m ′ of the fifteen is the center line m of the central part 13.
, The two shear center lines m and m ′ are located in the same horizontal plane.

With the cross-sectional structure as described above, the torsional rigidity of both ends 15, 15 of the cross beam 9 is set lower than the torsional rigidity of the central portion 13.

In order to increase the torsional rigidity of the central portion 13, the thickness of the central portion 13 may be increased instead of making this portion a closed section.

Next, the operation of the rear suspension device 1 will be described with reference to FIGS. A description will now be given of the left rear wheel (turning outer wheel) 3L side when the vehicle turns right. The torsional deformation of the entire cross beam 9 at the time of the right-handed roll is caused by the contribution of the torsional deformation of only the end portions 15 and 15 having a relatively low torsional rigidity and the contribution of the torsional deformation of only the central portion 13 having a high torsional rigidity. Think separately.

FIG. 3A shows a torsion state when the contribution of the torsional deformation of only the end portions 15 is considered. In this case, the torsion of the cross beam 9 is the shear center line m '.
As a result, the central portion 13 is displaced so as to rotate around the shear center line m '. Accordingly, intersection point P _a for an extension and the vehicle center section of shear center line m '(vertical plane) corresponds to a fixed point of the movement of the vehicle center section by the torsional deformation of the cross beam 9.

FIG. 3B shows a torsion state when the contribution of the torsion deformation of only the central portion 13 is considered. In this case, the torsion of the cross beam 9 is displaced so as to rotate around the shear center line m. Therefore, the intersection point P _b of the shear center line m and the vehicle center section corresponds to a fixed point of the movement of the vehicle center section by the torsional deformation of the cross beam 9.

FIG. 4A shows a torsion state when the torsion deformation of the entire cross beam 9 is considered. In this case, most of the torsional deformation is caused by the end 1 having low torsional rigidity.
Since occurring in 5, the fixed point P _t of the vehicle center section of the cross beam 9 at this time, as shown, the fixed point P _a,
It will be located closer to the P _a between the P _b. In other words, the fixed point P _t is in the position spaced significantly from the cross beam 9 forward.

[0043] FIG. 4 (b) shows how to determine the position of the fixed point P _t. In the figure, L: distance between the reference point O and the fixed point P _t of the vehicle center section of the crossbeam ds: minute section length of the crossbeam K: Torsional stiffness per unit length in a minute interval ds M: Torsional moment generated by cross beam 2θ: Relative rotation angle of right and left trailing arms (twist angle of cross beam) r: Shear center line connecting cross-sectional shear center in minute section ds and reference point O The distance L is determined by the following equation, where s is the half of the cross beam length.

[0044]

(Equation 1) Thus, the position of the fixed point P _t of the vehicle center section of the entire cross beam 9 is set to the large spaced position from the cross beam 9.

FIG. 5 shows a central axis of the torsional deformation of the rear suspension device 1. As shown, when the vehicle body rolls due to a right turn, the wheel support 5 of the turning outer wheel 3L is
Rotates about the axis A connecting the support center 7a of the elastic bushes 7 of the fixed point P _t and the trailing arm 5a. At this time, since the position of the fixed point P _t is set at a position spaced forwardly from the cross beam 9, the angle α is small relative to the axis A is the vehicle width direction line, car body side negative camber change of the outer ring 3L Is suppressed to a small value, and a change in turning characteristics can be suppressed.

In FIG. 5, as in FIG. 1, the fuel tank 11 is arranged close to the vehicle, and the cross beam 9 has to be arranged relatively rearward of the vehicle. by providing to extend obliquely rearward ends 15 low with respect to the central portion 13, the fixed point P _t can be separated from the cross beam 9 to the front, adjusted and set the tilt angle α of the axis a whereby However, desired camber angle change characteristics can be obtained.

Thus, according to the present embodiment, the torsional rigidity of both ends 15, 15 of the cross beam 9 is set lower than that of the central portion 13, and most of the torsional deformation is caused by the end 1
5, because there are restrictions on the vehicle layout,
It is possible to arrange sets spaced positions of the vehicle center section of the fixed point P _t of the entire cross beam 9 forward greatly from the cross beam 9.

Thus, the turning outer wheel 3L at the time of rolling the vehicle body
, The change in the negative camber with respect to the vehicle body can be suppressed small, the change in turning characteristics can be suppressed, and the running stability can be further improved.

[Second Embodiment] A second embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a rear view and a partial cross-sectional view showing a configuration outline of the rear suspension device 21 of the present embodiment, and FIG. 7 is an explanatory diagram showing a distribution of a shear center line.

The rear suspension device 21 includes two ends 35 of a cross beam (torsion beam member) 29,
The cross-section of the cross beam 29 differs from that of the first embodiment in that the cross-section of the cross-beam 29 is inclined obliquely downward in the vertical plane. Other configurations are the same as those of the first embodiment, and the description of the members denoted by the same reference numerals and overlapping description will be omitted.

As shown in FIG. 6 (rear view of the rear suspension device 21), the cross beam 29 has a central portion 33 extending horizontally in the vehicle width direction and a diagonally downward direction outward of the vehicle body in the same vertical plane. It has inclined both end portions 35. The left and right trailing arms (suspension arms) 5b are rotatably supported by the vehicle body-side frame member so that the elastic bush 7 at the front end thereof is vertically swingable at a low height above the ground. Therefore, the cross beam 29 connects the left and right trailing arms 5b, 5b at a low height above the ground.

As shown in each cross-sectional view of FIG. 6 (a cross-sectional view in the vertical direction at the central portion 33 and both ends 35, 35), the central portion 33 of the cross beam 29 is formed in a substantially square closed cross section. The torsional rigidity is high, and the shear center n exists in a closed section. On the other hand, both end portions 35, 35 are formed in an inverted V-shaped open cross section that opens downwardly of the vehicle body, and the torsional rigidity is formed lower than that of the central portion 33. The shear center n in each cross section is Centroid (not shown)
Is located in the vicinity of the upper and outer sides of the cross section, and is distributed in one vertical plane.

FIG. 7 (rear view of the cross beam 29) shows a distribution state of a shear center line connecting the shear centers n of the cross sections of the cross beam 29. As shown by the broken line in the figure,
In the central portion 33, the shear center line m extends substantially horizontally in the vehicle width direction, a shear center line m 'connecting the shear centers n of the both ends 35, 35 extends along the inclination of the end portion 35, and both shear center lines m , M ′ are in the same vertical plane.

[0054] With the configuration described above, as shown in FIG. 6, in the vehicle center section of the entire cross beam 29 fixed point (rotation center) P _t is the extension line and the vehicle center section of shear center line m ' located at the intersection P _a little below the (road surface), in a position spaced a greater upward from the cross beam 29.

Therefore, for example, FIG.
As P "point (side view), ground clearance is the layout of the cross beam 29, even when, as is limited low, can be increased placing ground height of the fixed point P _t.

[0056] Thus, in FIG. 6 (rear view), since the axis A connecting the support center 7a of the fixed point P _t and the trailing arm 5b is outside edge state, the turning outer wheel side at the time of the roll (car body side bound side Wheel (3L) changes toe angle in the toe-in direction (roll understeer).

As described above, according to the present embodiment, the torsional rigidity of both ends 35 of the cross beam 29 is reduced by the central portion 33.
, And most of the torsional deformation occurs at the end portion 35. Therefore, even if there is a restriction on the layout of the cross beam 29 as described above, the fixed point of the cross section of the center of the vehicle as a whole in the cross beam 29 cross the position of the P _t beam 29
It is possible to set the arrangement at a large distance from.

Thus, when the vehicle body rolls, the change in the toe angle of the turning outer wheel is set to the toe-in direction, and desired roll understeer characteristics can be obtained.

Third Embodiment A third embodiment of the present invention will be described with reference to FIGS. FIG. 8 is a plan view of the cross beam 59 of the present embodiment and a cross-sectional view taken along the arrow, and the upper part of the figure is the front of the vehicle. 9 and 10 are explanatory diagrams, and the contents of the diagrams will be described later. First, the configuration will be described.

The rear suspension device of the present embodiment
The structure of the cross beam (torsion beam member) 59 is different from that of the second embodiment (FIGS. 6 and 7). The other configuration is the same as that of the second embodiment, so that only the differences will be described, and redundant description will be omitted.

As shown in FIG. 8 (in plan view), the cross beam 59 has a central portion 63 extending horizontally in the vehicle width direction, and both ends 65, 65 extending on both sides thereof in the vehicle width direction. Each cross-sectional view of FIG.
As shown in FIG.
Is formed in a round pipe-shaped cross section (closed cross section) and has high torsional rigidity. Both ends 65, 65 are formed in a U-shaped cross section (open cross section) that opens substantially toward the rear of the vehicle, and a central portion 63 is formed. Is twisted downward diagonally once, and the twist is formed so that the twist continuously and gradually changes from this part outward diagonally upward, and the torsional rigidity is It is set lower than that of the central portion 63.

As shown in the cross-sectional views of FIG. 8, the center of shear n of the central portion 63 exists in a closed cross section, and both ends 6
In Nos. 5 and 65, it is located near the outside of the wall portion curved on the center line of the U-shaped cross section.

FIG. 9 (rear view) shows a distribution state of a shear center line connecting the shear centers n of the cross beams 59 of the respective cross sections. As shown by the broken line in the figure, in the central portion 63, the shear center line m extends substantially horizontally in the vehicle width direction, and the both ends 6
The shearing center line m ′ of 5,65 intersects the shearing center line m of the central portion 63 and is inclined downward in the vehicle width direction.

With such a configuration, the cross beam 59
Located in a fixed point of the entire vehicle center section (rotation center) P _t is slightly larger than the intersection point P _a for an extension and the vehicle center section of shear center line m 'lower (road surface), upward from the cross-beam 59 It is located at a distance.

Thus, according to the present embodiment, the second
The same operation and effect as in the embodiment can be obtained, and the cross beam 59 of the present embodiment has a more linear shape than the cross beam 29 (FIGS. 6 and 7) of the second embodiment, so that it is narrower. It can be applied and arranged in a space, which is more advantageous in terms of applicability.

The cross beam 59 of this embodiment is
Cross beam 9 in plan view of the first embodiment (FIG. 1)
Since the configuration does not have the inclined both end portions 15 as described above, it can be applied as a measure for solving the problem with the layout conflict factor.

FIG. 10 (plan view) shows a case where the toe angle change characteristic is improved by applying the cross beams 59 and 29 of the third embodiment (FIG. 8) and the second embodiment (FIG. 6). Next, the operation that occurs as a subsidiary will be described.

In the third and second embodiments, the cross beam 5
Fixed point (rotation center) P in the center cross section of the entire vehicle 9, 29
_Since the ground height of _t can be arranged higher than the main body of the cross beams 59 and 29, when the trailing arm 5a is fixed and considered, the cross beams 59 and 29 are twisted in a mode that deforms back and forth while being twisted. According to the configuration of the third and second embodiments, as shown in FIG. 10A, the amount of deformation B before and after this can be increased.

Actually, since the central portions 63 and 33 of the cross beams 59 and 29 are integrally connected to the both ends 65 and 35, as shown by a broken line in FIG.
The suspension makes a toe change with a lateral scuff change δ that pushes the turning outer wheel 3L outward. This scuff change makes the lateral movement of the vehicle more stable. That is, in the third and second embodiments,
Not only the toe angle change is improved, but also the tire scuff change accompanying the roll changes in a more desirable direction in terms of vehicle responsiveness and stability.

[Fourth Embodiment] A fourth embodiment of the present invention will be described with reference to FIGS. FIG. 11 is a plan view of a rear suspension device 71 of the present embodiment and a cross-sectional view taken along an arrow, and the upper part of FIG. 11 is the front of the vehicle. FIG. 12 is a rear view.

The rear suspension device 71 of the present embodiment
Differs from the first embodiment (FIG. 1) in the structure of the cross beam (torsion beam member) 79. The other configuration is the same as that of the first embodiment, so that only the differences will be described, and redundant description will be omitted.

As shown in FIG. 11 (a plan view of the rear suspension device 71) and FIG. 12 (a rear view), the cross beam 79 is disposed on the central portion 83 extending horizontally in the vehicle width direction and on both sides of the central portion 83. And both end portions 85, 85 extending inclining rearward and extending inclining downward. Then, as shown in each cross-sectional view of FIG.
3 is formed in a U-shaped closed section, and the shear center n in each section exists in the closed section. On the other hand, both ends 85, 85
Is formed in a U-shaped open cross section opened obliquely downward, and the shear center n in each cross section is located near the outside of the wall curved on the center line of the U-shaped cross section. Thereby, the torsional rigidity of the both ends 85, 85 is set lower than that of the central portion 83.

As shown by broken lines in FIGS. 11 (plan view) and FIG. 12 (rear view), in the central portion 83, a shear center line m connecting the shear centers n extends substantially horizontally in the vehicle width direction, and both ends 6
The shear center line m ′ of 5,65 intersects the shear center line m of the central portion 63 both in plan view and rear view. More specifically, it is inclined rearward in the plan view, and inclined downward in the vehicle width direction in the rear view. And the shear center line m
And m ′ are in the same plane inclined in the forward direction of the vehicle with respect to the road surface.

With this configuration, the cross beam 79
Position of the fixed point P _t of the total vehicle center section in a plan view and rear view, located slightly behind and below the intersection of each axis m 'and the vehicle center section, forward and upward from the cross-beam 79 It is located at a distance.

As described above, according to the present embodiment, the angle α formed by the axis A with respect to the vehicle width direction in a plan view is suppressed to a small value. The change in the negative camber is small, the change in turning characteristics can be suppressed, and the running stability can be further improved.

Further, since the axis A in the rear view falls outward, the change in the toe angle in the toe-in direction on the side of the turning outer wheel 3L (the wheel on the body bound side) at the time of rolling as in the second and third embodiments. (Roll understeer), and a desired roll understeer characteristic can be obtained.

[Fifth Embodiment] A fifth embodiment of the present invention will be described with reference to FIG. FIG. 13 is a perspective view showing the configuration of the rear suspension device 91 of the present embodiment. FIG.
In FIG. 3, almost the left is the front of the vehicle.

The present embodiment is different from the first embodiment in that a link called a so-called Panal rod is used and a cross-sectional shape of a cross beam (torsion beam member) is used. The other configuration is the same as that of the first embodiment, and a duplicate description will be omitted.

As shown in FIG. 13, the Panal rod 92
Is disposed at the rear side of the cross beam 99, one end 92a is swingably supported by the vehicle body-side member, and the other end 92b is supported by the wheel support 5 via an elastic bush. Is restrained. Also,
Left and right coil springs and shock absorber 94
Is attached to the wheel support 5.

The cross beam 99 is arranged horizontally, and its cross-sectional shape (illustration) is the same as that of the second embodiment (FIG. 6).
Similarly, the central portion 103 is formed in a substantially rectangular closed cross section, and the two end portions 105, 1 disposed on both sides of the central portion 103.
Reference numeral 05 is formed in a V-shaped cross section that opens rearward and extends obliquely rearward of the vehicle. Both ends 105, 105
Is set to be lower than that of the central portion 103.

With this configuration, the cross beam 99
Fixed point of the entire vehicle center section (rotation center) P _t is located slightly rearward than the intersection of the extension line and the vehicle center section of shear center line m 'of the end portions 105 and 105, the cross beam 99 Is located away from the front. The shear center line m of the central portion 103 and the shear center line m ′ (not shown) of both end portions 105 and 105 are in the same horizontal plane.

With this configuration, according to the present embodiment, the change in the negative camber of the turning outer wheel with respect to the vehicle body when the vehicle body rolls is obtained in the same manner as in the first embodiment, while being restrained in the lateral direction by the Panal rod 92. Can be kept small,
A change in turning characteristics can be suppressed, and running stability can be further improved.

[Sixth Embodiment] A sixth embodiment of the present invention will be described with reference to FIG. FIG. 14 is a plan view and a partial cross-sectional view of a cross beam (torsion beam member) 119 of the present embodiment. The upper part of FIG. 14 is the front of the vehicle.

In the present embodiment, the cross-sectional shape of the cross beam 119 is different from that of the first embodiment, and the other configuration is the same as that of the first embodiment.

As shown in FIG. 14, the cross beam 119
Are formed in a round pipe cross-sectional shape and extend horizontally in the vehicle width direction, and both end portions 125 formed in a round pipe cross-sectional shape smaller in diameter than the central portion 123 and extending obliquely rearward on both sides of the central portion 123. 125. Thus,
The torsional rigidity of both ends 125, 125 is set lower than that of the central part 123.

[0086] Then, the fixed point P _t of the vehicle center section of the entire cross beam 119 is located slightly rearward than the intersection point P _a shear center line m of the both end portions 125, 125 'and the vehicle center section, It is located away from the cross beam 119 forward.

With this configuration, according to the present embodiment, similarly to the first embodiment, the change in the negative camber of the turning outer wheel with respect to the vehicle body during rolling of the vehicle body can be suppressed to a small value, and the change in the turning characteristics can be suppressed. In addition, running stability can be further improved.

Further, since the cross beam 119 can be manufactured by a high-efficiency production method such as so-called hydroforming, the productivity is improved.

[Brief description of the drawings]

FIG. 1 is a plan view and a partial cross-sectional view showing a configuration outline of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating a distribution state of a shear center line according to the first embodiment.

FIG. 3 is an explanatory diagram of a torsion center of the first embodiment.

FIG. 4 is an explanatory view of a torsion center of the first embodiment.

FIG. 5 is an operation explanatory view of the first embodiment.

FIG. 6 is a rear view and a partial cross-sectional view showing a configuration outline of a second embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a distribution state of a shear center line according to the second embodiment.

FIG. 8 is a plan view of a main part and a cross-sectional view of an arrow part according to a third embodiment of the present invention.

FIG. 9 is an explanatory diagram illustrating a distribution state of a shear center line according to the third embodiment.

FIG. 10 is an operation explanatory view of the third embodiment.

FIG. 11 is a plan view of a fourth embodiment of the present invention and a cross-sectional view taken along an arrow.

FIG. 12 is a rear view of the fourth embodiment.

FIG. 13 is a perspective view illustrating a configuration outline of a fifth embodiment of the present invention.

FIG. 14 is a plan view and a partial cross-sectional view of a main part of a sixth embodiment of the present invention.

FIG. 15A is a sectional view of a main part of a conventional example, and FIG. 15B is a perspective view of the conventional example.

FIG. 16 is an operation explanatory view of a conventional example.

FIG. 17 is an operation explanatory view of a conventional example.

FIG. 18 is an operation explanatory view of a conventional example.

FIG. 19 is an operation explanatory view of a conventional example.

[Explanation of symbols]

3L, 3R Left and right rear wheels 5 Wheel support 5a, 5b Trailing arm (suspension arm) 7a Front end support point of trailing arm 9, 29, 59, 79, 99.119 Cross beam (torsion beam member) 13, 33, 63,83,103,123 central portion (lateral portion) 15,35,85,125 end m, m 'shear center line P _t fixed point of the vehicle center section

Claims (8)

[Claims] 1. Left and right wheel supports for supporting wheels are respectively attached to suspension arms extending forward of the vehicle, and the front ends of the suspension arms are rotatably supported on the vehicle body side so as to be able to swing up and down. The support or suspension arm
In a rear suspension device which is connected to a torsion beam member extending in a vehicle lateral direction and allowing torsional deformation, the torsion beam member is constituted by a lateral portion and both end portions extending on both sides of the lateral portion, and a shear of each cross section is provided. A shear center line connecting the centers extends substantially horizontally in the lateral portion, and extends crosswise at both ends, and the torsional rigidity of the both ends is set to be lower than the torsional rigidity of the lateral portion. A rear suspension device, characterized in that: 2. The rear suspension device according to claim 1, wherein the shear center lines at the both end portions are set to intersect with the shear center lines at the lateral portion in a plan view of the vehicle. And rear suspension device. 3. The rear suspension device according to claim 1, wherein the shear center lines at the both end portions are set to intersect with the shear center lines at the lateral portion in a rear view of the vehicle. A rear suspension device characterized by the following. 4. The rear suspension device according to claim 3, wherein the shear center lines of the both end portions are set so as to be inclined downward and extend with respect to the shear center line of the lateral portion in a rear view of the vehicle. A rear suspension device characterized by the following. 5. The rear suspension device according to claim 1, wherein the both end portions are provided near a joint between the torsion beam member and the wheel support or the suspension arm. Characteristic rear suspension device. 6. The rear suspension device according to claim 5, wherein said both end portions are formed in an open cross section, and a lateral portion is formed in a closed cross section. 7. The rear suspension device according to claim 5, wherein the both end portions have a shear center line at a position separated in one direction from the centroid of each cross section, and The rear suspension device wherein the shear center line exists in the same plane. 8. The rear suspension device according to claim 5, wherein the both end portions have a continuously twisted cross-sectional shape.