Double link type suspension system

Abstract

A double link type front suspension system for an automotive vehicle of the front engine front drive type or the four wheel drive type. The suspension system is comprised of upper and lower control arms adapted to connect a steering knuckle to a vehicle body. A shock absorber is disposed generally vertical so that its upper end section is connected to the vehicle body while its and the lower end section is relatively rotatably pivotally connected to by way of a joint formed on the upper portion of the knuckle to either the knuckle itself or the lower end of an intermediate arm which is connected between the upper section is made around arm and the knuckle. The lower control arm is connected to the knuckle by way of a ball joint. A steering axis is defined by a straight line (steering axis) passing through a the ball joint for connecting and the joint on the upper portion of the knuckle lower section and the lower control arm, thereby making possible to set the steering axis regardless of the upper control arm.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a double link type suspension system, for example, in use for an automotive vehicle, and more particularylocationalan on axle shaft 20 of the wheel 14 which shaft 20 is connected through a constant velocity joint 22 to a drive shaft 24 driven under the driving force from the engine.

The lower section 12a of a knuckle 12 is connected through a ball joint 26 to the outboard end section of a lower control arm 28 whose inboard end section is connected through a rubber (elastomeric) insulation bushing 30 to a bracket (not shown) of a vehicle body 31. The ball joint 26 includes a ball stud 26a secured to the knuckle lower section 12a, and a retainer 26b which is secured to the outboard end section of the lower control arm 28. The upper section 12b of the knuckle 12 rotatably connected to an extension bracket (member) 32 by a joint 34.

As best shown in FIG. 3, the joint 34 between the extension bracket lower end section 32a and the knuckle upper section 12b includes a joint bracket 32m which is secured to the lower end section 32a of the extension bracket 32 and has a generally C-shaped cross-section so as to have spaced and opposite plate sections (no numerals) which are respectively formed with openings (no numerals). The upper section 12b of the knuckle 12 extends upward and curved curves inward of the vehicle body in such a manner that the tip end portion thereof is situated between the opposite plate sections of the joint bracket 32m. The tip end portion of the knuckle upper section 12b is formed with a vertical through-hole 12m. A bolt 35a is disposed so as to pass through the openings of the joint bracket opposite plate sections and the through-hole 12m. A cylindrical sleeve 35b is fitted on the bolt 35a and situated within the through-hole 12m. Two rolling roller (ball) bearings 35c are securely disposed spaced from each other and between the tip end portion of the knuckle upper section 12b and the sleeve 35b. Accordingly, the knuckle upper section 12b is relatively rotatable with respect to the extension bracket lower end section 32a. The axis of rotation of the joint 34 (i.e., the axis of the bolt 35a) is aligned with the axis of the ball stud 26a of the ball joint 26 to form a steering axis (kingpin axis) 36, so that relative rotation between the knuckle upper section 12b and the extension bracket lower end section 32a is made around the steering axis 36. Since the joint 34 is adapted to connect the knuckle upper section 12a and the. extension bracket lower end section 32a in such a manner that the knuckle upper section 12a is relatively rotatable to the extension bracket lower end section 32a around the steering axis 36, it will be understood tht that the rolling roller bearings 35c may be replaced with sliding bearings. Additionally, although the joint 34 has been shown and described as using the rolling roller bearings 35c, it will be appreciated that the joint may be replaced with other means for relatively rotatably connecting the knuckle 12 and the extension bracket 32 in a condition in which the axis of rotation of the joint is aligned with the steering axis 36.

The extension bracket 32 is extended upward and curved outward relative to he the vehicle body 31 generally in a manner to surround the upper section of the wheel 13 so that the upper end section 32b of the extension bracket 32 reaches a position above the upper-most section 14a of the wheel 14. The extension bracket upper end section 32b is swingably pivotally connected through rubber (elastomeric) insulation bushings 38 to the outboard end section of an upper control arm 40 whose inboard end section is swingably pivotally connected through rubber (elastomeric) insulation bushings 42 to a bracket (not shown) of the vehicle body 31. It will be understood that the joint between the extension bracket 32 and the upper control arm 40 is sufficient to be one using the rubber insulation bushing 38 because the extension bracket 32 is merely swingable pivotal relative to the upper control arm 40.

As best shown in FIGS. 2 and 4, the above-mentioned joint between the extension bracket upper end section 32b and the upper control arm outboard end section includes a generally horizontally extending rod member 32n secured to the tip end portion of the upper end section 32b of the extension bracket 32 in such a manner that the tip end portion is positioned at the axially central part of the rod member 32n. The two rubber insulation bushings 38 are cylindrical and securely mounted on the rod member 32n, and located spaced from each other and on the opposite sides of the tip end portion of the extension bracket upper end section 32b. The upper control arm 40 is formed at its outboard end section with two cylindrical portions 40a which are spaced from each other and securely mounted respectively on the rubber insulation bushings 38A, 38B 38, 38. Accordingly, relative swinging pivotal movement between the extension bracket upper end section 32b and the upper control arm outboard end section is made under distortion of the rubber insulation bushings 38.

A shock absorber 44 is provided arranged to extend generally parallel with the extension bracket 32 and is generally vertically installed between the vehicle body 31 and the lower end section 32a of the extension bracket 32. The shock absorber 44 includes an outer tube 44a whose lower end section is connected through a rubber (elastomeric) insulation bushing 50 to the lower end section 32a of the extension bracket 32. A piston rod 44b extending from the outer tube 44a is connected through a mount rubber 46 to the vehicle body 31. Additionally, a coil spring 48 is disposed coaxially with the shock absorber 44 and installed between the mount rubber 46 and the shock absorber outer tube 44a 32a. In this connection, the extension bracket 44 is constructed of press-formed sheet metal and formed generally channel-shaped to have a generally C-shaped cross-section as clearly shown in FIG. 5. Thus, the extension bracket 44 32 includes an elongate base section 32t, and two side sections 32s which are integral with the base section 32r and located opposite to each other, thereby defining an elongate space in which at least a part of the shock absorber outer cylinder 44a and the coil spring 48 is situated. Accordingly, the extension bracket 44 covers the outer side (near the wheel 14) of the shock absorber outer tube 44a and the lowe-half lower half of the coil spring 48 in such a manner as to surround the shock absorber 44 and the part of the coil spring 48. As seen from FIG. 5, about half the outer periphery of the shock absorber 44 and the coil spring 48 is covered with the extension bracket 32. It will be understood that the generally channel-shaped channel shaped extension bracket 32 offers a higher exhibits increased structural strength to the extension bracket itself while allowing to narrow and allows the distance between the shock absorber 44 and the wheel 14 thereby to be reduced in a manner which tend to minimize the space occupied by them the same. The reference numeral 52 in FIG. 2 denotes an a knuckle arm which is connected to a steering linkage (not shown) through which a steering force or effort is transmitted to the knuckle 12.

Thus, in In this embodiment, a center line 54 of the wheel 14 (in the direction of width of the wheel in a cross-section including the axis of rotation of the wheel) crosses the steering axis 36 at a position above a horizontal plane 56 at which the wheel (tire) 14 is in contact with the ground or road surface as illustrated in FIG. 1. Furthermore, the steering axis 36 intersects the plane 56 at a position lying outward of the wheel center line 54 thereby to set a so-called negative scrub radius. It is to be noted that since the steering axis 36 is determined by locations of both the joint between the knuckle 12 and the extension bracket 32 and the joint between the knuckle 12 and the lower control arm 28, setting the scrub radius positive, negative or zero is not related unaffected by to the arrangement of the upper control arm 40. Consequently, the rubber insulation bushing 38 between the upper control arm 40 and the extension bracket 32 can be located without any restraint from the consideration of the orientation of steering axis 36. In this connection, in this embodiment, the rubber insulation bushings 38 are located above the wheel 14 so as to project outward relative to the vehicle body so that the rubber insulation bushings 38 and the wheel 14 overlap each other in the direction of width of the vehicle. This ensures a sufficient length of enables the upper control arm 40 to be long enough to obtain an optimum optimal wheel alignment while locating the inboard end section of the upper control arm 40 at a position near the outside of the vehicle in the direction of width of the vehicle. It will be understood that this a reason one of the reasons why the width of a wheel (tire) house is minimized thereby to enlarge the width of an the engine compartment.

Thus, ensuring By increasing the sufficient length of the upper control arm 40 minimizes it is possible to reduce the difference in length between the upper and lower contol control arms 40, 28 thereby making possible to obtain the optimum thus facilitating optimal wheel alignment. Additionally, since the vertical distance between the upper and lower control arms 40, 28 can be enlarged, variation of the camber .[∠]. and caster .[∠]. angles due to assembly error of the suspension component parts can be minimized while suppressing development of variation of the camber angle during vertical movement of the wheel 14. Additionally, the rigidity of both the arms 40, 28 increases proportional to the square of the distance between the both the arms, and therefore the rigidity of them is enlarged of the same is increased thereby improving the marginal performance of camber angle variation (Viz., reduce marginal variations in camber angle).

As will be appreciated, the weight of the vehicle body is supported by the wheel 14 through the mount rubber 46, the coil spring 48, the shock absorber outer tube 44a, the lower control arm 28 and the knuckle 12. The vertical movement of the wheel 14 can be damped under by expansion and contraction of the shock absorber 44 and absorbed under deflection of the coil spring 48. Here, during During vertical movement of the wheel 14, the knuckle 12 and the extension bracket 32 make their vertical movement together with the wheel 14, so that the lower and upper control arms 40, 28 swing pivot vertically. Along with this, the shock absorber 44 and the coil spring 48 make their expansion and contraction. Thus, since all such members make their vertical movement, no interference occurs between a section including the knuckle upper section 12b and the extension bracket 32 and another section including the shock absorber 44 and the coil spring 48.

It will be understood that when steering force or effort is transmitted from the steering linkage through the knuckle arm 52 integral with the knuckle 12, the knuckle 12 makes its rotation around the steering axis 36 thereby to turn the wheel 14 to steer the vehicle. At this time, the knuckle 12, wheel 14 and the axle shaft 20 turn around the steering axle 36 in which the knuckle 12 is rotatable at the joint 34 and therefore the extension bracket 32 does not turn. As a result, since the extension bracket 32 makes only the above-mentioned vertical movement along with the wheel 14 so that its relative movement to the upper control arm 40 is only swinging pivoting, a ball joint is unnecessary for the joint between the extension bracket 32 and the upper control arm 40, so that the rubber insulation bushings 38 are sufficient for this joint. The rubber insulation bushings 38 are smaller in height dimension than the ball joint, and consequently the height of the wheel house is minimized thereby lowering the level of the hood of the engine compartment. In this connection, the rubber insulation bushing is smaller by about 40 mm in height dimension than the ball joint usually used for a control arm of a double wish-bone type suspension system.

Furthermore, the fact that no rotation is made induced in the extension bracket 32 during vehicle steering leads to the fact of making no relative obviates displacement of the shock absorber 44 and the coil spring 48 with respect to the extension bracket 32 therby to prevent thereby preventing interference therebetween. In this connection, the extension bracket 32 is formed has a channel-shaped or C-shaped in cross-section thereby surrounding partially enclosing the shock absorber 44 and the coil spring 48. This extremely minimizes reduces the distance between the shock absorber 44 and the wheel 14, thus making possible to minimize the width of the wheel house thereby to enlarge the width of the engine compartment, in combination with the fact that freedom of location of the upper control arm 40 increases. It will be understood that, in this case, the shock absorber 44 and the coil sprung spring 48 are prevented from being injured with spring stone damaged by flying stones and the like since the shock absorber cylinder 44a and the coil spring lower part are covered or protected with the extension bracket 32.

Moreover, during vehicle starting or braking, the relative displacement force developed between the vehicle body 31 and the wheel 14, acts along an extension of the steering axis 36 on the upper control arm 40. In other words, the relative displacement force is input applied to a point P positioned midway between the inboard and outboard end sections of the upper control arm 40. Thus, such force input is made to at the position nearer to the vehicle body 31 than in a case in which the same force input is made to the outboard end section of the upper control arm 40, and therefore less load due to such force input is applied to a portion of the vehicle body 31 to which portion the inboard end section of the upper control arm 40 is attached. This makes it possible to lighten the weight of the vehicle body portion to which the upper control arm is attached, and minimize the size and soften the rubber insulation bushing 42 used in the joint between the upper control arm 40 and the vehicle body 31. Such softening of the rubber insulation bushing leads to an increase in absorption efficiency for of vibration input from the side of the wheel 14, thus reducing vehicle vibration and booming noise due to the vibration.

While the above-discussed embodiment has been shown and described to be so arranged that the lower end section of the shock absorber 44 is connected to the knuckle upper section 12a so that the weight of the vehicle body is not supported by the lower control arm 28 thereby to minimize the rigidity of the lower control arm 28 and the rubber insulation busing 30 and enlarge the space around the drive shaft 24, it will be appreciated that the lower end section of the shock absorber 44 may be supported to on the lower control arm 28 in which a considerable part of the shock absorber 44 is covered with the extension bracket 32 as discussed above.

As a result, the suspension system of the present invention offers jointly both the advantageous effects of the above-discussed first and second prior arts as shown in Table 1, and additionally offers the unique advantageous effects summerized summarized as follows:

(1) Since the extension member (bracket) does not turn during vehicle steering, it is possible to use the rubber insulation bushing in the joint between the an upper control arm and the extension member, thereby minimizing the height of the joint as compared with the case of using a ball joint. This minimizes the height of the wheel house thereby lowering the hood of the engine compartment.

(2) Since the relative displacement force developed between the vehicle body and the wheels during vehicle starting and braking is input to the upper control arm at a position lying on the extension of the steering axis, the thus input force is applied to a location nearer to the vehicle body than in the case where the same force is input to the outboard end of the upper control arm. Accordingly, less load due to the above-mentioned input force is applied to the arm attaching portion of the vehicle body, thereby making possible weight-lightening of the vehicle body arm attaching portion and minimizing and softening of the joint. Such softening of the joint suppresses vibration transmission to the vehicle body threby thereby to reduce booming noise due to the vibration transmission.

(3) Since setting of the steering axis can be accomplished regardless irrespective of the location and orientation of the upper control arm, the attaching location of the upper control arm to the vehicle body can be situated outward in the direction of the vehicle body width, so that the location of outboard end of the upper control arm is freely selectable variable. Thus, the width of the engine compartment is enlarged in combination with the above-mentioned reason. Additionally, it is posible possible to determine the length of the upper control arm appropriate to obtain a suitable wheel alignment.

FIG. 6 illustrates a second embodiment of the suspension system in accordance with the present invention, which is similar to the first embodiment except for the joint 34' between the shock absorber 44 an the knuckle upper section 12b, and the extension member 32 for connecting the shock absorber 44 and the upper control arm 40. In this embodiment, the lower end section of the shock absorber cylinder 44a is rotatably connected through two ball joints 60A, 60B to the upper section 12b of the knuckle 12. More specifically, a bracket 62 is secured to the lower end section of the outer tube 44a is formed with upper and lower flange sections 62a, 62b which are spaced from each other. Each ball joint 60A (60B) includes a ball stud 60a and a retainer 60b for the ball joint. The two ball joints 60A, 60B are located opposite to and generally symmetrical with each other in such a manner that the respective axes of the ball studs 62a are aligned with each other. The two ball studs 60a are respectively secured to the upper and lower flange sections 62a, 62b, while the two retainers 60b are secured to the tip end portion of the knuckle upper section 12b which tip end portion is situated between the upper and lower flange sections 62a, 62b. As shown, the axis of rotation of the joint 34' (i.e., the common axis of the two ball studs 60a) is aligned with the axis of the ball stud 26a of the ball joint 26 thereby to form the steering axis (kingpin axis) 36. Accordingly, relative rotation between the knuckle upper section 12b and the shock absorber lower end section is made around the steering axis 36. It will be understood that a sufficient clearance is formed between the ball joint 26 and the brake disc 16 to prevent interference therebetween.

The extension bracket 32 is fixedly secured at its one end section to the upper section of the piston cylinder 44a of the shock absorber 44 by means of a bolt 63 and at the other end to a rubber (elastomeric) insulation bushing 38 to the outboard end section of the upper control arm 40. Accordingly, the joint (including the bushing 38) between the extension bracket 32 and the upper control member 40 is vertically swingable pivotal as indicated in phantom. The coil spring 48 is wound around the shock absorber 44 in such a manner that the extension bracket 32 is interposed between adjacent coiled wire portions, in which the pitch of the coiled wire portions is increased at a position at which the extension bracket 32 is situated thereby to prevent interference between the coil spring 48 and the extension bracket 32 even during vertical swing pivot of the upper control arm owing to vertical movement of the wheel 14 or during contraction of the coil spring 48. It will be understood that interference between the coil spring 48 and the upper control arm 40 may be prevented in a similar manner if there is a possibility of interference therebetween. The reference numeral 63 denotes a tie rod of the steering linkage.

Thus, in this embodiment, the steering axis 36 crosses the wheel center line 54 at a point on the plane 56 at which the wheel 14 is in contact with the road surface, thereby providing zero scrub radius. It will be understood that the steering axis 36 is determined by a locational spatial relationship between the ball joint 26 and the ball joints 60A, 60B, and therefore the upper control arm 40 and the extension bracket 32 have no concern effect in making scrub radius negative, possitive positive or zero. Accordingly, the steering axis does not influence the disposition of the rubber insulation bushing 38 bushings 38, 38 in the joint between interconnecting the upper control arm 40 and the extension bracket 32 can be situated without being restrained from the steering axis 36, and therefore it is located just in a laterally outward position above the wheel 14 and outward relative to he vehicle body so tht the bushing 38 and the wheel 14 are overlapped in the width direction of the vehicle , thus ensuring a sufficient . This enables the length of the upper control arm 40 to be set so as to provide appropriate wheel alignment and locating locate the outboard end section of the upper control arm 40 at a position near the outside of the vehicle body in the vehicle width direction. It will be understood that this is a reason for reducing feature enables the width of the wheel (tire) tire house thereby to enlarge to be reduced and the width of the engine compartment and the like inside the wheel house to be correspondingly increased. Since the rubber insulation bushing 38 is situated just above the wheel 14, the upper control arm 40 and the shock abosrber absorber outer tube 44a are connected by the extension bracket 32, while force input in fore-and-aft and lateral directions of the vehicle is supported by the upper control arm 40 and the lower control arm 28.

Additionally, since the shock absorber 44 is disposed between the knuckle upper section 12b and the vehicle body 31 so that the shock absorber outer tube 44a serves also as an upwardly extending portion of the knuckle 12, only the shock absorber 44 and the coil spring 48 are so disposed as to vertically extend on at a location inward of the inside of the wheel 14 within the wheel house. It will be understood that this is also a reason for reducing the width of the wheel house thereby to enlarge the width of the engine compartment inside the wheel house.

Upon movement of the tie rod 64 of the steering linkage, the wheel 14 is turned together with the knuckle 12 to steer the vehicle, in which the turning of them is made around the steering axis 36. Similarly, also upon vertical movement of the wheel 14, turning movement not around other than about the steering axis 36 isdoes not developed since the steering axis 36 passes through the ball joints 60A, 60B, 26.

Furthermore, the shock absorber outer tube 44a and the extension bracket 32 behave as a single member with which is connected to the unsprung members, and therefore variation of camber, toe-in and the like is determined by the upper control arm 40 and the lower control arm 28 similarly insimilar to conventional wish-bore type suspension systems. The mount rubber 46 at the upper end of the shock absorber 44 receives horizontal force input from the shock absorber owing in response to movement of the upper control arm 40 and the lower control arm 28. This force input is adapted such as to make induce shearing action to of the mount rubber 46 and suppress inner stress and friction of in the mount rubber, consequently. Due to its configuration, the mount rubber 46 is low in exhibits a low rigidity against force input in horizontal direction. Additionally, against force input in vertical direction, the On the other hand, shock absorber 44 and the coil spring 48 work so that are arranged with respect to the mount rubber 46 has so that it exhibits a high rigidity under compression against force input in vertical direction. Thus, vertical force input is supported borne by the shock absorber 44 and the mount rubber 46, and additionally as the shock absorber 44 is supported connected to the knuckle upper section 12b. Consequently, the lower control arm 28 is not required to support the vertical force input and therefore no connecting member is provided between the shock absorber 44 and the lower control arm 28. This enlarges a increases the space around the bracket 62 of the joint between the shock absorber 44 and the knuckle upper section 12b, thereby increasing freedom of the ease with which pipings for a brake system (not shown) can be disposed.

When the wheel 14 bounds and the knuckle 12 moves upwardly, the coil spring 38 is compressed and the shock absorber outer tube 44a ascends thereby to cause upwardly move upward movement of the extension bracket 32 to upwardly move, so that the upper control arm upwardly swings pivots to a position indicated in phantom in FIG. 6. Thus, since the upper control arm 40 behaves like in the same manner the wheel 14 along with the during vertical movement of the wheel 14, no interference occurs between the wheel 14 and the upper control arm 40 and the extension bracket 32.

FIG. 7 shows a locational spatial relationship among which exists between the wheel 14, the upper control arm 40, the extension bracket 32 and the shock absorber outer tube 44a as viewed from the upper side of the wheel 14. The locational spatial relationship indicated in solid lines and by the character "A" corresponds to that of the second embodiment of FIG. 6. Other locational spatial relationships indicated in phantom and by the characters "B" and "C" correspond to examples in which the outboard end section of the upper control arm is merely connected to the shock absorber outer tube without using the extension bracket. As is appreciated from FIG. 7 employing the extension bracket 32 facilitates to allow permits the width of the wheel (tire) house defined by a vehicle body wall 31a to a minimized thereby ensuring a required length of the upper control arm, as compared with cases of "B" and "C" shown in phantom.

FIG. 8 shows a modified example of the joint 34' between the shock absorber outer tuber 44a and the knuckle upper section 12b. This joint 34' is similar to that used in the second embodiment of FIG. 6 with the exception that rolling roller bearings are used in place of the ball joints. In this example, the joint 34' includes the bracket 62, to which the lower end section of the shock absorber outer tube 44a is fixedly secured, which is formed with opposite and spaced flange sections 62a, 62b which are respectively formed with openings (no numerals). The tip end portion of the knuckle upper section 12b is situated between the flange sections 62a, 62b and formed with a through-hole (no numeral), in which a bolt 70 passes through the openings of the flange sections 62a, 62b and the through-hole of the tip end portion of the knuckle upper section 12b. Additionally, two annular ball bearings 72A, 72B are disposed spaced and coaxial between the bracket 62 and the tip end portion of the knuckle upper section 12b so as to allow smooth relative rotation therebetween. In this example, the axis of rotation of this joint 34' (i.e., the axis of bolt 70) is aligned with the steering axis 36.

FIG. 9 illustrates a third embodiment of the suspension system according to the preent present invention, which is similar to the second embodiment except for the deail detail of the joint 34', the extension bracket 32 and the coil spring 48. In this embodiment, the knuckle upper section 12b is formed with a cylindrical portion 12m which is positioned between two flange sections 62a, 62b of the bracket 62 to which the lower end section of the shock absorber outer tube 44a is secured. The flange sections 62a, 62b are located spaced from each other and formed respectively with openings (no numerals). The cylindrical portion 12m of the knuckle upper section 12b is slidably rotatably mounted on a bolt 80 through a cylindrical plastic bushing (sliding bushing) 82. The bolt 80 is secured to the bracket 62 in such a manner as to pass through the openings of the flange sections 62a, 62b. Accordingly, the shock absorber outer tube 44a is relatively rotatable to the knuckle upper section 12b of the knuckle is connected to the shock absorber outer tube 44a by the joint 34' whose so as to be rotatable abut the axis of rotation thereof (i.e. viz., the axis of the bolt 80) which axis is aligned with the steering axis 36 passing and which passes through the axis of the ball joint 26.

The lower end section of the extension bracket 32 is formed into the cylindrical shape and fitted on the outer tube 44a of the shock absorber 44. Additionally, the coil spring 48 disposed around the shock absorber 44 is tapered downwardly in order to facilitate connection to secure the lower end thereof to the outer tube 44a of the shock absorber 44. The pitch of the coiled wire portions of the coil spring 48 is enlarged at a section through which the extension bracket 32 extends, in order to prevent interference between the coil spring 48 and the extension bracket 32 like in similar to the second embodiment of FIG. 6. As seen from the Figure, in this embodiment, the steering axis 36 crosses the wheel center line 54 at a position above the plane at which the wheel (tire) 14 is in contact with road surface thereby to provide negative scrub radius like in similar to the first embodiment of FIG. 1.

While only the front suspension systems for the vehicles of the front engine front wheel drive type or the four wheel drive type have been shown and described, it will be understood that the principle of the present invention may be applicable to other suspension systems such as a front suspension system for a vehicle of the front engine rear wheel drive type.

TABLE 1
__________________________________________________________________________
Evaluation of effect
First
Second
Feature in                  Present
prior
prior
arrangement
Item   Effect             invention
art
art
__________________________________________________________________________
A case an
Assembly
Since the distance between the upper
A    A  D
The upper arm
accuracy
and the lower control arms is large,
is located at  variation of camber angle and caster
a higher angle due to assembly error is small.
high position
Rigidity
Since the distance between both
B    B  D
as in the
against
control arms is large, rigidity
Note 1)
first prior
camber angle
against variation of camber angle is
art     variation
large. In other words, the rigidity
increases proportional to the square
of the distance between both the
control arms. (As a result, marginal
performance of camber angle variation
is high).
Force input
Since the distance between both the
B    B  D
to upper
control arms is large, force input to
Note 1)
control arm
the vehicle body is small relative to
lateral and fore-and-aft direction
forces and the like at a ground-
contacting plane of the tire. As a
result, rigidity of the upper control
arm can be minimized thereby to
weight-lighten it and lower production
cost.
Variation of
Since the distance between both the
B    B  D
camber angle
control arms, almost no camber angle
variation is hardly developed even
under vibration of both the control
arms.
Adaptation
An FF vehicle requires a drive shaft
A    A  D
for FF for the front wheels, and therefore
vehicle
there is no space for the  upper
control arm inside ain board of the
road wheel.
A case The
Variation of
Since the upper control arm
As   D  A
upper control
camber angle
longer so as to be small in long
arm is         and reduces the difference between it
longer   and the lower control arm,
lengthened, and
evariation variation of camber angle
the steering
is made smaller reduced.
axis is set
Space in
Since the upper control arm can
Be   D  B
relardless
vehicle body
projected outward of vehicle body, the
regardless
frame (1)
width of engine compartment is
of the upper   enlarged.
control arm as
Space in
Since  the upper control arm
Bs   C  B
in the second
vehicle body
longer long, the distance of
prior art
frame (2)
entering amount of entry of tire
upper-most section into vehicle body
is smaller during bound, the width of
engine compartment can be enlarged.
Jack-down
During vehicle turning, displacement
B    D  B
amount of both control arms is
smaller reduced, and tendency of
down-force development is smaller
reduced.
A case a
Space in
There As there is no
Aelative
D  C
The steering
vehicle body
displacement between the extension
Note 3)
axis is set
frame (3)
bracket and the shock absorber, it is
regardless of  possible to narrow the space
the upper
therebetween. Accordingly, the width
upper control  of the engine compartment is enlarged.
arm, and the
Height of
Since the extension bracket does
Aot  D  C
upper control
Hood from
turn, the joint between the upper
Note 2)
arm is  the ground
control arm outboard end and the
longer   extension bracket is sufficient to
lengthened,
employ can be a bushing.
and situated
Consequently, the height dimention
at a higher    dimension of the joint is minimized as
position and   compared with in the case of ball
disposed       joint, thereby lowering wheel house by
near the       about 40 mm.
outside of
Force Input
Force input to the upper control
Brm  D  D
the vehicle
during is made at a point P in the drawing
braking and
but not at the outboard end (pivot
starting
point), and it is possbile that force
input to the vehicle control arm
attaching portion is minimized, the
vehicle body is weight-lightened, and
the bushing is small-sized (improving
durability) and softened (improving
noise and vibration absorption
effect).
Length of
If the vehicle body side inboard
A    D  C
upper  pivotal position of the upper
Note 3)
control arm
arm is sufficiently projected outward
of the vehicle body in order to
enlarge engine compartment, freedom
of selection of the position of the
bushing at the contro arm outboard
end section is larger increased,
thereby ensuring permitting a
suitable length of the control arm.
__________________________________________________________________________
Meaning of character for "Evaluation of Effect":
A . . . excellent
B . . . good
C . . . insufficient
D . . . no effect
Note
1) Chassis frame is necessary in connection with rigidity against camber
angle variation.
2) There are no control arms and bushings located at higher
high positions at all.
3) Interference between upper control arm and an axle occurs if the upper
control arm is made longer.

Claims

1. A double link type suspension system for a vehicle, comprising:

a knuckle for rotatably supporting a wheel of the vehicle;

a lower control arm having a first end section movable pivotally connected to a lower section of said knuckle by a first joint, and a second end section movably pivotally connected to side of a vehicle body;

a shock absorber having a first end section which is connected to the vehicle body side, and a second end section relatively movably operatively connected to an upper section of said knuckle, by way of a joint means in such a manner that said shock absorber being knuckle is relatively rotatable to said knuckle around with respect to said shock absorber about a straight line passing through said first joint and said joint means;

an extension member having a first end sectionand a second end section, the first end section being connected to one of said shock absorber, and a second end section and said knuckle; and

an upper control arm having a first end section movably pivotally connected to the second end section of said extension member, and a second end section pivotally connected to the vehicle body side.

2. A double link type suspension system as claimed in claim 1, wherein said shock absorber is disposed generally vertical and near said extension member.

3. A double link type suspension system as claimed in claim 1, wherein the vehicle is of a front engine front wheel drive type.

4. A double link type suspension system as claimed in claim 1, wherein the vehicle is a four wheel drive type.

5. A double link type suspension system as claimed in claim 1, wherein said wheel has an axle shaft connected through a constant velocity joint to a drive shaft which is driven by an engine, said axle shaft being rotatably journalled by said knuckle.

6. A double link type suspension system as claimed in claim 1, wherein said first joint is a ball joint whose axis is aligned with said straight line.

7. A double link type suspension system as claimed in claim 6, wherein said ball joint includes a ball stud secured to said knuckle lower section, said ball stud having an axis aligned with said straight line, and a retainer for movably supporting said ball stud, secured to said lower control arm.

8. A double link type suspension system as calimed claimed in claim 1, wherein said knuckle upper section and said shock absorber second end section are connected by a second joint through which said straight line passes, and said extension member second end section and said upper control arm first end section are connected by a third joint, said third joint being separate from located between a vertical plane containing a point in a horizontal plane passing through said third joint, said straight line passing through said point, said third joint being located between said vertical plane containing said point which lies on said straight line and a wheel vertical plane containing center line of said wheel and perpendicular to axis of rotation of said wheel.

9. A double link type suspension system as claimed in claim 8, wherein said straight line serves as a steering axis.

10. A double link type suspension system as claimed in claim 8, wherein said point resides in said upper control arm and separate from said third joint.

11. A double link type suspension system as claimed in claim 10, wherein said straight line intersects said wheel vertical plane at a point above a horizontal plane at which said wheel is in contact with road surface.

12. A double link type suspension system as claimed in claim 11, wherein said straight line intersects said horizontal plane at a point outside of said wheel vertical plane in a lateral direction of the vehicle body.

13. A double link type suspension system as claimed in claim 1, wherein said knuckle upper section is rotatably connected to said extension member first end section to which said shock absorber second end section is connected.

14. A double link type suspension system as claimed in claim 13, wherein said shock absorber second end section is connected through an elastomeric bushing to said extension member first end section.

15. A double link type suspension system as claimed in claim 13, wherein second joint includes a joint bracket fixedly secured to said extension member first end section, a rod member secured to said bracket, a sleeve member mounted on said rod member, means defining a through-hole in said knuckle upper section, said sleeve member being situated within said through-hole, and annular ball bearings disposed between said sleeve and said knuckle upper section.

16. A double link type suspension system as claimed in claim 1 3, wherein said third joint includes a rod member fixedly secured to said extension member second end section, and first and second elastomeric bushings securely mounted on said rod member and located on the opposite sides of said extension member second end section, said upper control arm first end section being mounted on said elastomeric bushings.

17. A double link type suspension system as claimed in claim 16, wherein said upper control arm first end section has first and second cylindrical portions which are respectively mounted on said first and second elastomeric bushings.

18. A double link type suspension system as claimed in claim 1, wherein said suspension member is has a generally channel-shaped cross-section and is disposed to surround at least enclose part of periphery of said shock absorber.

19. A double link type suspension system as claimed in claim 18, wherein said extension member is formed of a press-formed sheet metal and includes a generally vertically extending base plate portion located between said shock absorber and said wheel, and first and second side plate portions integral with said base portion and extending along said base portion, said base plate portion and first and second side plate portions defining an elongate space in which at least a part of said shock absorber is positioned.

20. A double link type suspension system as claimed in claim 1, wherein said straight line intersects said wheel vertical plane at a point on a horizontal plane at which said wheel is in contact with road surface.

21. A double link type suspension system as claimed in claim 8, wherein said second joint includes a support bracket to which said shock absorber second end section is fixedly secured, and first and second ball joints disposed between said support bracket and said knuckle upper section, axes of said first and second ball joints being aligned with each other and aligned with said straight line.

22. A double link type suspension system as claimed in claim 21, wherein each ball joint includes a ball stud secured to said support bracket, and a retainer for movably supporting pivotally mounted on said ball stud, the retainer being secured to said knuckle upper section, and wherein the axes of the ball studs of said first and second ball joints being are aligned with each other and aligned with said straight line.

23. A double link type suspension system as claimed in claim 22, wherein said support bracket has first and second flange sections which are spaced from each other so that a part of said knuckle upper section is interposed therebetween, said ball studs of said first and second ball joints being fixedly secured respectively to said first and second flange sections.

24. A double link type suspension system as claimed in claim 1, wherein said first end section of said extension member is fixedly secured to an outer tube of said shock absorber.

25. A double link type suspension system as claimed in claim 8, wherein said second joint includes a support bracket to which said shock absorber second end section is fixedly secured, a rod member secured to said support bracket, means defining a through-hole in said knuckle upper section, said rod member passing through said through-hole, and first and second annular ball bearings disposed between said support bracket and said knuckle upper section and coaxial with said rod member, said first and second annular ball bearings being separate from each other.

26. A double link type suspension system as claimed in claim 8, wherein said third joint is situated above the outer peripheral surface of said wheel.

27. A double link type suspension system as claimed in claim 8, wherein said second joint includes a support bracket to which said shock absorber second end section is fixedly secured, a rod member fixedly secured to said support bracket, a cylindrical sliding bearing mounted on said rod member, a part of said knuckle upper section being mounted on said sliding bearing.

28. A double link type suspension system as claimed in claim 27, wherein said sliding bearing is a plastic bushing.

29. A double link type suspension system as claimed in claim 8, wherein said extension member first end section is formed with a cylindrical portion fitted on an outer tube of said shock absorber.

30. A double link type suspension as claimed in claim 1, wherein said joint means comprises:

a second joint which is formed on said knuckle and which provides a pivotal connection between the knuckle and the second end section of said extension member; and

a pivot connection which interconnects the second end section of said shock absorber and the second end section of said extension member at a location proximate said second joint. 31. A double link suspension system for a vehicle, comprising:

a knuckle on which a road wheel is rotatably supportable;

a first joint;

a lower control arm having an outboard section pivotally connected to a lower section of said knuckle by said first joint, and an inboard end section adapted for pivotal connection to a vehicle body;

a shock absorber, said shock absorber having a connection member adapted for connection to the vehicle body;

an upper control arm having an inboard end and an outboard end, the inboard end being adapted for pivotal connection to said vehicle body;

an extension member having a first end and a second end, the first end being pivotally connected to the outboard end of the upper arm, the second end being connected to said shock absorber; and

a second joint, said second joint pivotally connecting an upper section of said knuckle to one of said shock absorber and the second end of said extension member, said first and second joints being arranged such that said knuckle is pivotal with respect to said extension member about an axis which passes through the first and second joints.

A double link suspension system for a vehicle, comprising:

a knuckle on which a road wheel is rotatably supportable;

a lower control arm having an outboard section which is pivotally connected to a lower section of said knuckle by a first joint, and an inboard end section which is adapted for pivotal connection to a vehicle body;

an extension member having an upper end and a lower end, the lower end being pivotally connected to said knuckle by a second joint, the first and second joints being arranged such that said knuckle is pivotal about an axis which passes through the first and second joints;

an upper control arm having an outboard end which is pivotally connected to the upper end section of said extension member, and an inboard end section which is adapted for pivotal connection to said vehicle body; and

a shock absorber having an upper end which is adapted for connection to the vehicle body, and a lower end which is pivotally connected to the lower

end section of said extension member. 33. A double link suspension system for a vehicle, comprising:

a knuckle on which a road wheel is rotatably supportable;

a lower control arm having an outboard end which is pivotally connected to a lower section of said knuckle by a first joint, and an inboard end which is adapted for pivotal connection to a vehicle body;

a shock absorber having an upper end which is adapted for connection to the vehicle body, and a lower end section operatively connected to an upper section of said knuckle by a second joint in such a manner that said knuckle is relatively rotatably with respect to said shock absorber about a straight line passing through said first joint and said second joint;

an extension member having first end and a second end, the first end being rigidly connected to said shock absorber; and

an upper control arm having an outboard end which is pivotally connected to the second end of said extension member, and an inboard end which is adapted for pivotal connection to said vehicle body. 34. A double link suspension system for a vehicle, comprising:

a knuckle;

means for rotatably supporting a road wheel on said knuckle;

means defining a first joint on a lower portion of said knuckle;

means defining a second joint on an upper portion of said knuckle;

a lower control arm having an outboard section which is pivotally connected to the lower section of said knuckle by said first joint, and an inboard end section which includes means for pivotally connecting the inboard end to a vehicle body;

an extension member having an upper end and a lower end, the lower end being pivotally connected to said knuckle by said second joint, the first and second joints being arranged such that said knuckle is pivotal with respect to said lower control arm and said extension about an axis which passes through the first and second joints;

an upper control arm having an outboard end which is pivotally connected to the upper end section of said extension member, and an inboard end section including means for pivotally connecting the inboard end to a vehicle body; and

a shock absorber having an upper end which includes means for connecting the upper end to a vehicle body, and a lower end which is pivotally connected to the lower end section of said extension member.

35. A double link suspension as claimed in claim 34 wherein said extension member has a channel shaped cross-section and said shock absorber is disposed in such a manner as to be partially enclosed by said extension member.