Front suspension

A front suspension for an automotive vehicle includes a wheel supporting member for rotatably supporting a road wheel of the vehicle. A lower link has a first end section rotatably connected to a lower section of the wheel supporting member, and a second end section connected to a vehicle body-side member so as to be swingable generally in a vertical direction of the vehicle. A connection member is rotatably installed to an upper section of the wheel supporting member so as to be rotatable around a first axis which passes through the wheel supporting member and extends generally in the vertical direction of the vehicle. A shock absorber has an upper end section pivotally connected to the vehicle body-side member, and a lower end section swingably connected to the connection member to be rotatable around a second axis which extends generally in a fore-and-aft direction of the vehicle. A spring is supported by the shock absorber and has a third axis. The extension of the third axis is separate from an extension of the first axis on a horizontal plane extending in a horizontal direction of the vehicle. The third axis inclines relative to the first axis on a vertical plane extending in a vertical direction of the vehicle. An upper link has a first end section swingably connected to the connection member, and a second end section swingably connected to the vehicle body-side member. The upper link has a fourth axis which connects a first connecting point at which the first end section is connected to the connection member and a second connecting point at which the second end section is connected to the vehicle body-side member. The fourth axis crosses the first axis on the vertical plane and on the horizontal plane. Additionally, a tie rod is provided to turn the wheel supporting member upon its movement in the width direction of the vehicle in accordance with a steering operation for the vehicle.

The contents of Japanese Patent Application No. 8-264855, with a filing 
date of Oct. 4, 1996 in Japan, are hereby incorporated by reference. 
BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to improvements in a front suspension of an 
automotive vehicle, and more particularly to the improvements in a front 
suspension of the type possessing both features of a strut type one and a 
double wishbone type one. 
2. Description of the Prior Art 
A variety of front suspensions have been hitherto proposed and put into 
practical use in the field of automotive vehicle. One of them is disclosed 
in Japanese Patent Provisional Publication No. 5178041. This front 
suspension is for an automotive vehicle and includes a steering knuckle 
(wheel supporting member) which has a lower end section which is swingably 
connected through a lower arm to a vehicle body (or a vehicle body-side 
member). A connection member is pivotally connected to the upper end 
section of the steering knuckle so as to be rotatable around the axis of a 
vertical shaft (or an installation shaft) projected from the upper end 
section of the steering knuckle. The connection member is pivotally 
connected to the lower end of a damper or shock absorber so as to be 
generally vertically swingable. An upper arm has one end section which is 
pivotally connected at a single point with the vehicle body, and another 
end section which is connected rotatably around the axis of a connection 
shaft extending generally in the fore-and-aft direction of the vehicle. 
More specifically, the latter end section of the upper arm is, for 
example, bifurcated to form two end portions which are located forward and 
rearward in the fore-and-aft direction of the vehicle. The two end 
portions are pivotally connected at respective two points with the 
connection member. The thus arranged front suspension is provided with 
advantages of both the strut type one and the double wishbone type. That 
is, the front suspension has an alignment similar to that of the double 
wishbone type one as viewed from the front of the vehicle thereby 
exhibiting a high stiffness against force input from a lateral direction 
even if the upper arm is disposed at a lower position, while has an 
alignment similar to that of the strut type one as viewed from a side of 
the vehicle thereby allowing to locate at a higher position the vehicle 
body-side connecting point of the shock absorber serving substantially as 
an upper arm thus attaining both a low stiffness in the fore-and-aft 
direction and a high caster stiffness. As a result, by appropriately 
combining both the features of the strut and double wishbone type 
suspensions, good ride-in comfortableness and driving stability can be 
obtained. 
However, drawbacks have been encountered in the above-discussed 
conventional front suspension in which the upper arm is rotatable only 
around the axis of the connection shaft extending in the fore-and-aft 
direction of the vehicle, for example, because the upper link is connected 
at the two points with the connection member. That is, when the connection 
member is in a condition to rotate around the axis of the installation 
shaft upon receiving force input from the spring, the upper link does not 
positively make its displacement because the upper link is pivotally 
connected with the connection member to be allowed to make its vertical 
swinging movement and is pivotally connected at the single point with the 
vehicle body-side member. In other words, when a vertical force is input 
to a front wheel, the upper link makes only its vertical swinging 
movement, so that movements (such as a movement under distortion of an 
elastic bushing) other than this vertical swinging movement are 
restricted. As a result, the connecting points between the connection 
member and the upper link cannot displace in directions other than the 
vertical swinging movement directions when a vertical force is applied to 
the front suspension or when the front wheel moves vertically, i.e., under 
wheel stroke, thereby not positively affecting the movement of the front 
wheel. Therefore, it is impossible to positively change the alignment of 
the front suspension when the vertical force is applied to the suspension 
and to appropriately set change in alignment under the vertical movement 
of the front wheel. 
BRIEF SUMMARY OF THE INVENTION 
The present invention has been developed to be intended to solve the above 
drawbacks encountered in the conventional front suspension. According to 
the present invention, an upper link is connected at a single point with a 
connection member. By virtue of this, freedom in layout for the front 
suspension can be improved maintaining good performance (such as 
stiffness) of the front suspension, while causing the connection member to 
be rotated under the force of a spring of a strut thereby appropriately 
setting toe angle and camber angle of the front wheel during vertical 
movement of the front wheel. Additionally, the movement of the front wheel 
(such as camber angle change) during the vertical movement of the front 
wheel can be appropriately set by taking account of the rotational 
movement of the connection member in addition to a so-called suspension 
geometry including length and angle of the upper link and lower link 
determined, for example, by layout and distortion of elastomeric bushings 
used in sections other than the upper link. These effectively improve 
driving stability of the vehicle. 
It is an object of the present invention to provide an improved front 
suspension for an automotive vehicle, which effectively overcomes 
drawbacks encountered in conventional front suspensions for an automotive 
vehicle. 
Another object of the present invention is to provide an improved front 
suspension for an automotive vehicle, which can improve freedom in layout 
of the front suspension while maintaining an appropriate balance among 
camber stiffness, lateral stiffness and the like of the front suspension. 
A further object of the present invention is to provide an improved front 
suspension for an automotive vehicle, which can appropriately set toe 
angle and camber angle of a front wheel and set movements (such as camber 
angle change) of the front wheel, thereby making it possible to suitably 
set movement of a front tire. 
A still further object of the present invention is to provide an improved 
front suspension for an automotive vehicle, in which the axis of a spring 
of a strut and the axis of a connection member are in a so-called 
torsional locational relationship, so that a displacement occurs between 
an upper link and the connection member under the action of force of the 
spring. 
A front suspension of the present invention is for a vehicle and comprises 
a wheel supporting member for rotatably supporting a road wheel of the 
vehicle. A lower link has a first end section rotatably connected to a 
lower section of the wheel supporting member, and a second end section 
connected to a vehicle body-side member so as to be swingable generally in 
a vertical direction of the vehicle. A connection member is rotatably 
installed to an upper section of the wheel supporting member so as to be 
rotatable around a first axis which passes through the wheel supporting 
member and extends generally in the vertical direction of the vehicle. A 
shock absorber has an upper end section pivotally connected to the vehicle 
body-side member, and a lower end section swingably connected to the 
connection member to be rotatable around a second axis which extends 
generally in a fore-and-aft direction of the vehicle. A spring is 
supported by the shock absorber and has a third axis. The extension of the 
third axis is separate from an extension of the first axis on a horizontal 
plane extending in a horizontal direction of the vehicle. The third axis 
inclines relative to the first axis on a vertical plane extending in a 
vertical direction of the vehicle. An upper link has a first end section 
swingably connected to the connection member, and a second end section 
swingably connected to the vehicle body-side member. The upper link has a 
fourth axis which connects a first connecting point at which the first end 
section is connected to the connection member and a second connecting 
point at which the second end section is connected to the vehicle 
body-side member. The fourth axis crosses the first axis on the vertical 
plane and on the horizontal plane. Additionally, a tie rod is provided to 
turn the wheel supporting member upon its movement in the width direction 
of the vehicle in accordance with a steering operation for the vehicle. 
According to the principle of the present invention, the upper link is 
connected at the single connecting point to the connection member so as to 
be simply swingable, thereby being prevented from being connected to be 
swingable only around an axis extending generally in the fore-and-aft 
direction of the vehicle. Additionally, the upper link axis or fourth axis 
(connecting the first connecting point at which the upper link is 
connected to the connection member and the second connecting point at 
which the upper link is connected to the vehicle body-side member) crosses 
the axis (the first axis) of the connection member at the crossing point 
on the vertical and horizontal planes. Accordingly, freedom in layout can 
be improved while maintaining an appropriate balance among camber 
stiffness, lateral stiffness and the like of the front suspension. 
Furthermore, the extension of the axis (the third axis) of the spring is 
separate from the extension of the axis (the first axis) of the connection 
member on the horizontal plane, and the axis of the spring inclines 
relative to the axis (the first axis) of the connection member on the 
vertical plane. In other words, the axis of the spring and the axis of the 
connection member is in a so-called torsional locational relationship, and 
therefore a displacement occurs between the upper link and connection 
member under the action of force of the spring, thereby enabling movement 
of a front tire to be set. This makes it possible to appropriately set toe 
angle and camber angle of the front wheel by displacing the upper link 
with the rotational movement of the connection member under vertical force 
input to the front wheel, and to appropriately set movements (such as 
camber angle change) of the front wheel by causing the connection member 
to rotate also under vertical movement of the wheel or wheel stroke, thus 
suitably controlling movements of the front tire.

DETAILED DESCRIPTION OF THE INVENTION 
Referring now to FIGS. 1 to 5 of the drawings, an embodiment of a front 
suspension according to the present invention is illustrated by the 
reference character F. The suspension F of this embodiment is for a left 
front (road) wheel of an automotive vehicle, and therefore another similar 
suspension is used for a right front wheel in such a manner as to be 
located generally symmetrical to the suspension F shown in FIG. 1. 
Although a pair of the front suspensions are thus generally symmetrically 
provided, explanation of the present invention will be made on only the 
front suspension for the left front wheel for the purpose of simplicity of 
illustration. 
The front suspension F comprises a steering knuckle or wheel supporting 
member 1 for rotatably supporting the left front wheel. The steering 
knuckle 1 includes a cylindrical section 1a into which a front axle or 
drive shaft of the front wheel is inserted so as to be rotatably 
supported. The cylindrical section 1a is formed at a vertically central 
section of the steering knuckle 1. The steering knuckle 1 includes a lower 
end section 1b to which a lower link 4 is connected through a ball joint 
3. The steering knuckle 1 further includes an upper end section 1c to 
which an upper link 6 and a strut 7 are connected through a rotational 
joint J. A tie rod 8 is connected to a tie rod support section 1d which is 
located at the vertically central section 1c of the steering knuckle 1 and 
projects rearward relative to the vehicle. 
The lower link 4 is disposed extending in the direction of width of the 
vehicle and has an outboard-side end section (no numeral) which is 
pivotally connected through the ball joint 3 to the lower end section 1b 
of the steering knuckle 1. The inboard-side end section (no numeral) of 
the lower link 4 is bifurcated to form two end or link portions (no 
numeral) which are respectively connected through elastomeric bushings 4a, 
4b to a vehicle body-side member such as a suspension member 14, so that 
the lower link 4 takes the generally A-shape in plan. Accordingly, the 
lower link 4 allows vertical movements of the steering knuckle 1 or bound 
and rebound of the front wheel but obstructs movement of the steering 
knuckle 1 in the fore-and-aft direction of the vehicle. 
The rotational joint J includes an installation shaft K which extends 
upward from the upper end section 1c of the steering knuckle 1. The 
installation shaft K has an axis L.sub.K which is aligned with the 
extension of a kingpin axis which passes through the center (or a 
connecting point R in FIG. 4) of the ball joint 3. The connecting point R 
is contained in a connecting section between the outboard-side end section 
of the lower link 4 and the lower end section 1b of the steering knuckle 
1. The rotational joint J further includes a rotatable connection member 5 
which is rotatably mounted or supported on the installation shaft K 
through bearings (not shown). Accordingly, the axis of the rotatable 
connection member 5 is also aligned with the axis L.sub.K and the 
extension of the kingpin axis. It will be understood that the axis L.sub.K 
extends generally vertically relative to the vehicle. 
The rotatable connection member 5 includes a shaft cylinder 5d which is 
rotatably and coaxially mounted on the installation shaft K in a manner to 
cover the installation shaft K. The shaft cylinder 5d is integrally 
provided with two support sections 5e, 5f which respectively project 
outward and inward in the width direction of the vehicle. The support 
sections 5e, 5f are respectively adapted to support the upper link 6 and a 
shock absorber 15. The support section 5e is formed generally cylindrical 
and provided thereinside with a cylindrical elastomeric bushing 5g. The 
axis of the generally cylindrical support section 5e extends generally in 
the fore-and-aft direction of the vehicle. The support section 5f is 
formed generally cylindrical and has an axis which extends generally in 
the fore-and-aft direction of the vehicle. A connection shaft 10 is 
inserted through the generally cylindrical support section 5f. 
The upper link 6 includes a generally I-shaped link section (no numeral) 
which extends generally in the width direction of the vehicle. In 
practice, the I-shaped link section slightly inclines relative to the 
width direction of the vehicle and therefore precisely does not extend in 
the width direction of the vehicle as discussed after. A pivot shaft 11 
extends generally in the fore-and-aft direction of the vehicle, from the 
outboard-side end portion of the I-shaped link section. The pivot shaft 11 
is inserted inside the elastomeric bushing 5g located inside the support 
section 5e, in such a manner that its tip end portion projects out of the 
support section 5e. The tip end portion of the pivot shaft 11 is formed 
with a threaded part on which a nut 31 is engaged and tightened. 
Accordingly, the outboard-side end section of the upper link 6 is 
pivotally connected to the rotatable connection member 5. 
The inboard-side end portion of the I-shaped link section of the upper link 
6 is integrally provided with a pivot shaft (not shown) which extends 
generally in the fore-and-aft direction and disposed inside an elastomeric 
bushing 13 which is disposed inside a generally cylindrical support 
section 14a forming part of the suspension member 14. Accordingly, the 
inboard-side end section of the upper link 6 is pivotally connected to the 
suspension member 14. The suspension member 14 is connected through a 
suspension member insulator 14b to a side member M. The upper link 6 is 
disposed such that the I-shaped link section extends passing by the front 
side of the rotatable connection member 5 of the rotational joint J, and 
inclines relative to the width direction of the vehicle in a manner that 
the outboard-side end portion of the I-shaped link section is located 
forward relative to the inboard-side end portion of the I-shaped link 
section as shown in FIG. 5. 
As shown in FIGS. 1 and 2, the upper link 6 has an axis (referred to as an 
"upper link axis") L.sub.U which crosses the axis L.sub.K of the 
installation shaft at a crossing point P. The upper link axis L.sub.U 
passes through a first point Q1 which is the axial center of the 
cylindrical elastomeric bushing 5g located inside the support section 5e, 
and a second point Q2 which is the axial center of the cylindrical 
elastomeric bushing 13 located inside the support section 14a. The axial 
center of the cylindrical elastomeric bushing 5g, 13 corresponds to a 
pivotal center which cannot be moved even if a rotational torque is 
applied to each bushing 5g, 13. 
The upper link axis L.sub.U is perpendicular to the axis of the cylindrical 
elastomeric bushing 5g and the axis of the cylindrical elastomeric bushing 
13 as seen in FIG. 2. The first point Q1 serves as a connecting point 
between the upper link 6 and the rotatable connection member 5 and is 
located at the outboard side relative to the axis L.sub.K of the 
installation shaft in the vehicle as shown in FIGS. 1 and 2. A connecting 
section (containing the connecting point Q1) between the upper link 6 and 
the rotatable connection member 5 is to be positioned inside an 
inboard-side depression of the front wheel (not shown). The second point 
Q2 serves as a connecting point of a connecting section between the upper 
link 6 and the vehicle body-side member 14. 
The strut 7 includes a shock absorber 15 which has a cylinder tube 15a. A 
spring 16 is disposed around the upper section of the shock absorber 15. A 
generally C-shaped support bracket 17 is fixedly installed to the lower 
end of the cylinder tube 15a. The support bracket 17 is swingably 
connected to the support section 5f of the rotatable connection member 5. 
The shock absorber 15 has a piston rod 15b which projects from the upper 
end of the cylinder tube 15a. The upper end section of the piston rod 15 b 
is secured through a mound rubber 18 and an installation plate 19 to the 
vehicle body-side member 14 such as a strut tower or the like. 
Here, brief and clear explanation will be made on a structure for 
connecting the cylinder tube 15 a of the shock absorber 15 to the upper 
end section 1c of the steering knuckle 1. The C-shaped support bracket 17 
is integrally provided at its opposite end sections with two cylindrical 
members 17a, 17a each of which is provided thereinside with a cylindrical 
elastomeric bushing 12. The cylindrical members 17a, 17a are coaxial with 
each other and spaced from each other so that the support section 5f of 
the rotatable connection member 5 is interposed therebetween. The 
connection shaft (such as the bolt or the like) 10 is inserted through the 
inside holes (not identified) of the cylindrical members 17a, 17a and of 
the support section 5f of the rotatable connection member 5 which inside 
holes are in a condition to be aligned with each other. The thus inserted 
connection shaft 10 is in a state where the opposite end sections project 
respectively from the outer ends of the cylindrical members 17a, 17a. Nuts 
(no numeral) are respectively screwed on the projected opposite end 
sections of the connection shaft 10 and tightened in position, so that the 
C-shaped support bracket 17 is rotatably connected to the rotatable 
connection member 5. Accordingly, the shock absorber 15 is connected to 
the rotatable connection member 5 in such a manner the shock absorber 15 
is allowed merely to rotate around the axis extending generally in the 
fore-and-aft direction of the vehicle and prevented from other rotations 
and swinging movements although a slight swingable movement in all 
directions are possible under deformation of the elastic bushings 12, 12. 
The upper end of the spring 16 is directly installed through the support 
plate 20 or the like to the vehicle body-side member 14 such as the strut 
tower or the like. The lower end of the spring 16 is directly installed 
through the support plate 21 to the cylinder tube 15a of the shock 
absorber 15. In the arrangement of FIG. 3, large vibration input is 
transmitted through the path P1, whereas fine vibration input is 
transmitted through the path P2. 
In this embodiment, as shown in FIG. 2, the shock absorber 15 and the 
spring 16 are disposed at the inboard side relative to the axis L.sub.K of 
the installation shaft K to which the rotatable connection member 5 is 
coaxially mounted so as to avoid interference with the front wheel or the 
like. The spring 16 is arranged as follows: The axis L.sub.S of the spring 
16 is generally parallel with the axis L.sub.K of the installation shaft K 
for the rotatable connection member 5 as viewed from the front of the 
vehicle or on an imaginary vertical plane extending in the width direction 
of the vehicle, as illustrated in FIG. 2; however, the axis L.sub.S is 
inclined forward of the vehicle relative to the axis L.sub.K as viewed 
from the side of the vehicle or on an imaginary vertical plane extending 
in the fore-and-aft direction of the vehicle, as illustrated in FIG. 4. In 
other words, the axis L.sub.K and the axis L.sub.S are arranged offset or 
separate from each other on an imaginary horizontal plane. In other words, 
the extension of the axis L.sub.K and the extension of the axis L.sub.S is 
not parallel with each other and do not cross each other at a crossing 
point, in three-dimensions. Thus, the axis L.sub.K and the axis L.sub.S 
are in a so-called torsional locational relationship, in which the angle 
of inclination in the fore-and-aft direction of the vehicle is set smaller 
than the caster angle of the axis L.sub.K which serves substantially as 
the king pin axis as shown in FIG. 4. Additionally, as seen in FIG. 2, the 
axis L.sub.S of the spring 16 passes through a connecting point (vehicle 
body-side connecting point) S assumed at the center of a connecting 
section between the spring 16 and the vehicle body-side member 14 such as 
the strut tower or the like passes, and passes through the axis L.sub.P of 
the connection shaft 10 on which the support bracket 17 for the shock 
absorber 15 is rotatably supported. More specifically, the axis L.sub.S of 
the spring crosses the axis L.sub.P at a crossing point, or passes through 
a center of the axis L.sub.P of the connecting shaft 10 which center 
corresponds to the axial center of the inside hole of the support section 
5f of the rotatable connection member 5. 
The tie rod 8 is connected to a steering gear (not shown) to cause the 
steering knuckle 1 to rotate around the axis L.sub.K so as to steer the 
vehicle. 
Function of the above front suspension F will be discussed in detail 
hereinafter. 
The front suspension F of this embodiment assumes a double wishbone type 
suspension including the lower link 4 and the upper link 6 as viewed from 
the fore-and-aft direction of the vehicle while a strut type suspension 
including the lower link 4 and the strut 7 as viewed from the width 
direction of the vehicle. Accordingly, the front suspension F of this 
embodiment can exhibit advantages of both the wishbone type and strut type 
suspensions and omit the shortcomings of them. More specifically, as 
viewed from the front of the vehicle as illustrated in FIG. 2, the 
movement of the front wheel (movement of the steering knuckle 1) with 
wheel stroke is restricted by the lower link 4 and the upper link 6, and 
therefore the front suspension F functions like the double wishbone type 
one. As viewed from the lateral direction of the vehicle as illustrated in 
FIG. 4, the same movement of the front wheel is restricted by the lower 
link 4 and the shock absorber 15, and therefore the front suspension F 
functions like the strut type one. Regarding force input to the front 
wheel and the steering knuckle 1, the force input in the fore-and-aft 
direction is received by the lower link 4 and the strut 8 like in the 
strut type suspension; while the force input in the lateral direction is 
received by the lower link 4 and the upper link 6 like in the double 
wishbone type. 
Accordingly, the front suspension F of this embodiment can obtain a high 
stiffness against a force input from the lateral direction of the vehicle 
by disposing the upper link at a lower position as viewed from the front 
of the vehicle. Additionally, the front suspension F can obtain a high 
caster stiffness and lower the stiffness against a force input in the 
fore-and-aft direction of the vehicle since the vehicle body-side 
connecting point S of the shock absorber serving practically as an upper 
link is disposed at a higher position as viewed from the front of the 
vehicle. Thus, both high ride-in comfortableness and driving stability of 
the vehicle can be attained by suitably combining the features of the 
double wishbone type and strut type suspensions. Furthermore, in this 
embodiment, the upper link is disposed at the lower position as discussed 
above, the suspension F can be small-sized and obtains high stiffness and 
precision by installing the suspension F to the suspension member 14. 
When a lateral force directing to the inboard side of the vehicle acts on 
the steering knuckle 1, for example, during a turn of the vehicle, the 
lateral force reached to the steering knuckle 1 is then transmitted to the 
rotatable connection member 5 since the lower section of the steering 
knuckle is restrained from its movement in the width direction of the 
vehicle under the action of the lower link 4, and therefore the lateral 
force is applied to the axis L.sub.K (serving as the kingpin axis) of the 
installation shaft K for the rotatable connection member 5. The strut 7 
including the shock absorber 15 hardly generates a reaction against the 
lateral force since the connection shaft 10 is disposed extending in the 
fore-and-aft direction of the vehicle. In contrast, a large reaction 
against the lateral force can be generated at the upper link axis L.sub.U 
since the upper link axis L.sub.U crosses the axis L.sub.K of the 
installation shaft K for the rotatable connection member 5 at the crossing 
point P. In other words, only compressive or tensile axial force simply 
acts on the upper link axis L.sub.U upon omitting a minute force generated 
owing to torsion of each elastomeric bushing disposed at the connecting 
section between the upper link 6 and the vehicle body-side member 14 and 
between the upper link 6 and the rotatable connection member 5, thereby 
generating no moment for causing the rotatable connection member 5 to 
rotate around the axis L.sub.K of the installation shaft K for the 
rotatable connection member 5. It is to be noted that when a lateral force 
is input through the steering knuckle 1 so that a reaction along the upper 
link axis L.sub.U serves as a component force, a small force to be applied 
in the fore-and-aft direction of the vehicle is generated as a component 
force, since the upper link axis L.sub.K is arranged inclined relative to 
the width direction of the vehicle. This small force acts on the rotatable 
connection member 5; however, it is received by the strut 7 similarly to 
in case that the fore-and-aft direction force acts on the front wheel as 
discussed above, and therefore no lowering is made in camber stiffness and 
in lateral stiffness under a condition where the upper link 6 and the 
rotatable connection member 5 are connected at the single connecting 
point. 
In this connection, in the conventional front suspension as disclosed in 
Japanese Patent Provisional Publication No.5-178041, moment for rotating 
the rotatable connection member is generated under the action of the axial 
force of the upper link and force input from the installation section of 
the steering knuckle to the rotatable connection member. In order to 
prevent generation of such moment, it is necessary that installation of 
the upper link to the rotatable connection member is made in such a manner 
that the upper link is rotatable only around the axis extending in the 
fore-and-aft direction of the vehicle. Accordingly, it is required that, 
for example, the upper link is connected at two points with the rotatable 
connection member. 
In this embodiment, when a force input in the fore-and-aft direction of the 
vehicle is made onto the steering knuckle, the fore-and-aft direction 
force input is applied through the axis L.sub.K of the installation shaft 
K for the rotatable connection member 5 under a normal condition where the 
connection shaft 10 for connecting the strut 7 and the rotatable 
connection member 5 is directed in the fore-and-aft direction of the 
vehicle. This force input can be resisted by reactions applied to the 
connection shaft 10 for connecting the strut 7 and the rotatable 
connection member 5 and to the vehicle body-side connecting point S 
located at the upper part of the strut 7, thereby securely preventing the 
steering knuckle 1 from displacing in the fore-and-aft direction. 
Additionally, when the connection shaft 10 between the strut 7 and the 
rotatable connection member 5 moves to rotate around the axis L.sub.K 
corresponding to the kingpin axis, it is assumed that the rotatable 
connection member 5 and the strut 7 rotate around the axis L.sub.K of the 
installation shaft for the rotatable connection member 5 and round the 
axis of the strut 7. In this case, it seems necessary to change the length 
of the upper link 6; however, such rotational displacement cannot occur in 
practice under the action of reaction of the upper link 6. 
Further, in this embodiment, the outboard-side end section of the upper 
link 6 is supported to the support section 5e at the outboard side of the 
rotatable connection member 5, and therefore the length of the upper link 
6 can be set larger. This optimizes change in camber angle caused with 
wheel stroke, and reduces an angle of twist of the elastomeric bushing 
under a condition where an axial force is applied to the upper link, 
thereby linearizing the durability of the bushing and the camber angle 
change while improving ride-in comfortableness of the vehicle. 
Each of the elastomeric bushings 5g, 13 disposed respectively inside the 
support section 14a of the vehicle body-side member 14 and the support 
section 5e of the rotatable connection member 5 is arranged such that its 
axis is perpendicular to the upper link axis L.sub.U . This can minimize a 
force to be applied in the axial direction of the upper link 6, i.e., a 
displacement amount of the elastomeric bushing upon application of an 
axial force to the upper link, thereby maintaining an appropriate balance 
among camber stiffness, lateral stiffness and the like. 
In this embodiment, the axis L.sub.K of the installation shaft K for the 
rotatable connection member 5 passes through the center of the ball joint 
(bushing) 3 which center serves as the connecting point between the 
steering knuckle 1 and the lower link 4. In other words, the axis L.sub.K 
of the installation shaft K is aligned with the kingpin axis. Accordingly, 
even though the steering knuckle 1 is turned through the tie rod 8 by the 
steering gear to steer the front wheel, the rotatable connection member 5 
makes no rotation so that force input with steering the front wheel cannot 
act on the upper link 6. 
Thus, in this embodiment, each opposite end section of the upper link 6 is 
connected at the single point with the vehicle body-side member 14 or the 
steering knuckle 1 while securely preventing camber stiffness and lateral 
stiffness from being lowering. As a result, freedom in layout is increased 
to avoid interference and the like of the front suspension F with a tire 
and/or an installation section of the front wheel particularly during 
steering the front wheel, and additionally it is made possible to reduce 
weight and production cost of the front suspension F. Further, by suitably 
selecting the spring constant of the spring 16 of the strut 7, the elastic 
coefficient of the elastomeric bushings and the length of the links, 
different front suspensions suitable for different kinds of vehicles can 
be arranged while making it possible to use the same front suspension 
commonly in different kinds of vehicles. 
Furthermore, the front suspension F of this embodiment employs the 
particular support structure for the shock absorber 15 and the spring 16 
to constitute the input separation type strut. Additionally, the axis 
L.sub.S of the spring 16 crosses the axis L.sub.P of the connection shaft 
10 between the shock absorber 15 and the rotatable connection member 5 to 
form a crossing point, as shown in FIG. 2. As a result, a rotational 
torque around the axis L.sub.P of the connection shaft 10 cannot be input 
as a bending force onto the shock absorber 15 when a vertical force due to 
the vehicle weight or the like is input to the front wheel, thereby 
reducing a friction of the shock absorber thus to improve the ride-in 
comfortableness of the vehicle. 
In addition, when upward force is input to the front wheel, for example, 
owing to load of the vehicle and uneven condition of a road, the spring 16 
provides downward force against the upward force onto the shock absorber 
15 thereby establishing a balance between the upward and downward forces. 
The downward force from the spring 16 presses downward the cylinder tube 
15a of the shock absorber 15, and therefore it is input to the rotatable 
connection member 5 through the support bracket 17 and the elastomeric 
bushings 12, 12. At this time, the rotatable connection member 5 generates 
a rotational torque around the axis L.sub.K of the installation shaft for 
the rotatable connection member 5 under the action of the force of the 
spring 16, since the axis L.sub.S of the spring 16 and the axis L.sub.K of 
the installation shaft for the rotatable connection member 5 are not 
parallel with each other and do not cross each other at any crossing point 
thereby establishing the so-called torsional locational relationship 
between the axes L.sub.S and L.sub.K as discussed above. However, the thus 
generated rotational torque can be balanced upon distortion of the 
elastomeric bushing 5g at the connection section between the rotatable 
connection member 5 and the upper link 6. Accordingly, as viewed from the 
above or in plan as shown in FIG. 5, the rotatable connection member 5 
generates a rotational torque around the axis L.sub.K of the installation 
shaft K for the rotatable connection member 5, so that the elastomeric 
bushing 5g disposed inside the support section 5e (the connection section 
between the rotatable connection member 5 and the upper link 6) is 
distorted. At this time, under the action of a reaction of the distortion 
of the elastomeric bushing, a forward force F.sub.OUT is generated at the 
outboard-side end section of the upper link 6, and simultaneously a 
rearward force F.sub.IN is generated at the inboard-side end section of 
the upper link 6. As a result, as illustrated in FIGS. 6A and 6B, the 
upper link 6 is displaced at its side of the rotatable connection member 5 
or of the steering knuckle 1, forward in the vehicle. Thus, in case that 
the inboard(vehicle body)-side end section of the upper link 6 is located 
rearward in the vehicle relative to the rotatable connection member 5 as 
in this embodiment, the steering knuckle (1) side of the upper link 6 
moves forward and simultaneously moves toward the inboard side of the 
vehicle, so that a negative camber is provided to the front wheel. 
Additionally, the front section of the rotatable connection member 5 and 
the knuckle 1 located forward of the tie rod 8 are moved toward the 
inboard side of the vehicle, so that a toe-in is provided to the front 
wheel. Therefore, in case that the front wheel is an outside wheel in a 
turn of the vehicle, a turning performance of the vehicle can be improved. 
In contrast, in case that the inboard(vehicle body)-side end section of the 
upper link is located forward relative to the rotatable connection member, 
it will be apparent that when a rotational torque is applied to the 
rotatable connection member like in the above, the upper link moves in the 
opposite directions to that in the above in the width direction of the 
vehicle so that the front wheel moves in the opposite direction to that in 
the above since the supporting point for displacement of the upper link is 
different from that in the above. Additionally, as shown in FIG. 7, in 
case that the axis L.sub.S of the spring 16 inclines rearward relative to 
the axis L.sub.K of the installation shaft K for the rotatable connection 
member 5 as viewed from the side of the vehicle or on a vertical plane 
perpendicular to the width direction of the vehicle, a counterclockwise 
torque is applied to the rotatable connection member 5 conversely to the 
above. As a result, the outboard-side end section of the upper link 6 
moves rearward, so that a positive camber and a toe-out are provided to 
the front wheel thereby improving the stability of the vehicle in a turn. 
The reaction of the spring 16 increases and decreases with vertical 
movements of the front wheel. The toe angle, the camber angle, and the 
like of the front wheel can be changed in accordance with change in the 
spring reaction with the wheel stroke. Accordingly, change in camber angle 
and toe angle determined mainly in accordance with the layout and the like 
of suspension links can be appropriately set even in case that there is no 
freedom in layout, thus improving driving stability of the vehicle. 
Furthermore, in this embodiment, the elastomeric bushing is disposed in the 
connection section between the upper link 6 and the vehicle body-side 
member 14 and between the upper link 6 and the rotatable connection member 
5, and therefore the elastomeric bushing can suitably make its elastic 
deformation to be distorted under the action of the rotational torque 
which is from the rotational connection member 5 and generated by the 
reaction of the spring 16, so that a suitable angular change against the 
rotational torque can be obtained. Additionally, even in case that there 
is no precise crossing point at which the upper link axis L.sub.U and the 
axis L.sub.K of the installation shaft for the rotatable connection member 
5 cross each other, for example, under production tolerance, a moment 
according to the distance of the axes can be received by the torsional 
rigidity of each elastomeric bushing thereby exhibiting the same function 
as that discussed above. 
In this embodiment, the axis L.sub.S of the spring 16 and the axis L.sub.K 
of the installation shaft for the rotatable connection member 5 are always 
in the torsional locational relationship. In other words, the extensions 
of the axes L.sub.S and L.sub.K are in the locational relationship to be 
not parallel with each other and do not cross each other at a crossing 
point. Accordingly, even in a condition where there is no substantial 
wheel stroke, a reaction is generated at the spring 16 which receives the 
vehicle weight, and therefore the rotational torque is generated in the 
rotatable connection member 5, so that deformation due to torsion occurs 
or will occur in the elastomeric bushing 5g in the connecting section 
between the rotatable connection member 5 and the upper link 6 and in the 
elastomeric bushing 13 in the connecting section between the upper link 6 
and the vehicle body-side member 14. However, the rotational torque to be 
applied to the rotatable connection member 5 under the action of the 
reaction of the spring 16 and the displacement of the upper link due to 
the reaction force are for setting the appropriate alignment changes such 
as the camber angle, the toe angle change and the like when the wheel 
stroke is make. Accordingly, by causing the rotational torque not to be 
applied to the rotatable connection member 5 in a condition where there is 
no wheel stroke, the elastomeric bushing does not or will not make its 
deformation due to the torsion, thereby making it possible to expect to 
improving the durability of the elastomeric bushing in an amount 
corresponding to no deformation. In order to attain such an arrangement, 
the axis L.sub.S of the spring 16 and the axis L.sub.K of the installation 
shaft K for the rotatable connection member 5 are arranged to be parallel 
with each other, and/or the extensions of the axes L.sub.S, L.sub.K cross 
each other at a crossing point under a condition where no wheel stroke is 
made. 
While the lower link 4 has been shown and described as being of the single 
body taking the A-shape in plan in the above embodiment, it will be 
understood that the lower link 4 may be constituted of two link members 
which are separate from each other, each link member having the generally 
I-shape. In this case, the two link members are forward and rearward lower 
link members which are respectively disposed forward and rearward in the 
vehicle. The forward lower link member is extended generally in the width 
direction of the vehicle, in which the outboard-side end section of the 
forward lower link member is rotatably connected through a ball joint or 
the like to the front part of the lower end section 1b of the steering 
knuckle 1, and the inboard-side end section of the same link member is 
connected through the elastomeric bushing (4a) to the vehicle body-side 
member such as the suspension member. The rearward lower link is curved to 
bulge forward in the vehicle and disposed inclined relative to the width 
direction of the vehicle in such a manner that the inboard-side end 
section is located rearward relative to the outboard-side end section. The 
outboard-side end section is rotatably connected through a ball joint or 
the like to the rear part of the lower end section 1b of the steering 
knuckle 1, and the inboard-side end section is connected through the 
elastomeric bushing 4b to the vehicle body-side member such as the 
suspension member. 
The restraining action of the lower link constituted of the two link 
members to the steering knuckle is not problematic because the two link 
members are assumed to be formed by merely separating the A-type lower 
link. It is to be noted that the substantial connecting point R between 
the lower link and the steering knuckle corresponds to a crossing point of 
a first line connecting the vehicle body-side connecting point and the 
steering knuckle-side connecting point of the foreword lower link member 
and a second line connecting the vehicle body-side connecting point and 
the steering knuckle side connecting point of the rearward lower link 
member. Accordingly, as viewed from the front of the vehicle, freedom in 
setting the inclination angle of the (imaginary) kingpin can be increased 
relative to the embodiment of FIGS. 1 to 5 in an amount corresponding to 
the outboard-direction shift of the substantial connecting point R between 
the lower link and the steering knuckle. This offers the following 
advantages: In case that a front suspension including the thus arranged 
lower link is employed in a front-wheel-driving vehicle, the kingpin 
inclination angle is enlarged so that a so-called scrub radius (a distance 
between the crossing point of the kingpin with the road surface and a 
center of the road contacting surface of the tire) is set negative, 
thereby suppressing toe-in change due to torque steer during driving and 
omitting a turning moment for applying a large braking force to one of the 
front wheels in a turn of the vehicle. This improves driving stability of 
the vehicle while improving ride-in comfortableness of the vehicle by 
suppressing so-called shimmy phenomena which is caused upon transmission 
of the resonance vibration of a steering gear (under force input from road 
surface) to a steering wheel. 
While the above-discussed embodiment has been shown and described as 
employing the strut 7 of the input separation type wherein force inputs to 
the vehicle body from the spring 16 and the shock absorber 15 are made 
respectively through separate paths, it will be appreciated that the strut 
7 may be of a so-called input concentration type wherein the force inputs 
to the vehicle body from the spring 16 and the shock absorber 15 are made 
through the same path as shown in FIG. 8 obtaining the same advantageous 
effects as those in the above-discussed embodiment. In this input 
concentration type strut 7, the axis L.sub.S of the spring 16 passes 
through the connecting point S between the shock absorber 15 and the 
vehicle body-side member 14 and passes through the axis L.sub.P of the 
connection shaft 10 between the shock absorber 15 and the rotatable 
connection member 5. Accordingly, a rotational torque cannot be input 
around the axis L.sub.P of the connection shaft 10 between the shock 
absorber 15 and the rotatable connection member 5 even when a vertical 
force due to the vehicle weight and the like is input to the front wheel, 
thereby making it possible to reduce friction of the shock absorber thus 
improving the ride-in comfortableness of the vehicle.