RUBBER TORSION SUSPENSION SPRING FOR LIGHTWEIGHT MOTOR VEHICLE

Abstract: An automobile includes a plastic body and a steel frame bonded to the plactic body. The rear suspension system of the automobile includes a suspension arm coupled to a rear wheel. An arm shaft extends transversely inwardly from the arm and is embedded in a rubber cartridge press-fit into the frame, to thereby attenuate motion of the suspension arm. A horizontally-mounted longitudinally-oriented shock absorber further interconnects the suspension arm and frame. This shock absorber orientation avoids transferring suspension system loads to the plastic body.

Description: SUSPENSION SYSTEM The present invention relates generally to vehicle suspension systems, and more particularly to suspension systems for lightweight motor vehicles. As is well known, consumers demand a choice between many different models of automobiles. Depending on the circumstances-, some consumers might desire a simple yet effective automobile, with the principal and indeed overriding consideration being cost. With this in mind, the present invention recognizes that it is possible to provide an effective and useful automobile, the cost of which can be minimized by minimizing the weight of the automobile and by using the novel structure disclosed herein. More specifically, the present invention recognizes that a useful, low-cost, lightweight automobile can be provided which has a molded plastic body consisting essentially of a unitarily molded left half side bonded to a unitarily molded right half side. It will readily be appreciated that a molded plastic body is both lightweight, compared to metal automobile bodies, and inexpensive, compared to, e.g., fiberglass automobile bodies. As further recognized by the present invention, by making an automobile body of lightweight molded plaβtic, weight bearing components such as suspension springs can be simplified vis-a-vis weight bearing components of heavier steel-bodies automobiles. Consequently, the overall cost of the lightweight automobile can be even further reduced relative to heavier automobiles. It happens, however, that the present invention still further recognizes that in making an automobile body of plastic, additional changes beyond simplification must be made to the automobile suspension system relative to existing suspension systems. For instance, in existing automobile suspension systems, elongated shock absorbers are mounted vertically between the suspension springs and the body of the automobile, with the body thus providing load support for the shock absorbers. The present invention recognizes that plastic automobile bodies unfortunately cannot easily provide sufficient load support for shock absorbers. Indeed, as recognized herein the load of the shock absorbers on the plastic body, were the shock absorbers to be connected directly to the body, could crack and otherwise damage the body. Simply reinforcing the plastic body to support the shock absorber load would tend to undesirably increase the cost of the automobile and would not necessarily be effective in preventing body damage over prolonged automobile use. Accordingly, it iβ one intent of the present invention to support suspension system shock absorbers with structure other than the automobile body. It is therefore an object of the present invention to provide a suspension system for a lightweight automobile that incorporates a relatively simple design. Another object of the present invention is to provide a suspension system for a lightweight automobile that is effective in stabilizing the automobile. Still another object of the present invention is to provide a suspension system for a lightweight automobile in which shock absorbers are not connected directly to the body of the automobile. Yet another object of the present invention is to provide a suspension system for a lightweight automobile that is easy to use and cost-effective to manufacture. A suspension system for a motor vehicle having a frame and a rear wheel includes a rigid hollow frame beam that is connected to the frame. A resilient, preferably rubber, cartridge is disposed in the frame beam, and a rigid suspension arm has a first end coupled to the rear wheel. Further, an arm shaft is connected to the suspension arm and is distanced from the first end of the suspension arm, with the arm shaft being embedded in the resilient cartridge. Thereby, relative motion between the shaft and cartridge is subβtantially prevented to consequently attenuate rotational motion of the arm shaft relative to the cartridge. Preferably, the frame beam extends transversely across the motor vehicle. In one presently preferred embodiment, the resilient cartridge defines a hexagonal cross section having a distance between opposed sides of approximately three and one- half inches (3.5") . To firmly connect the arm shaft to the suspension arm, the arm shaft is splined to the suspension arm. And, to firmly connect the cartridge to the frame beam, the cartridge is press fit into the frame beam. Still further, the arm shaft iβ bonded to the resilient cartridge by vulcanization. Preferably, the arm shaft extends through the cartridge. In another aspect of the preβent invention, an apparatus includes an automobile including a plastic molded body, a rear wheel, and a frame. The apparatus alβo includeβ a suspension system coupling the rear wheel to the frame, and the suspension system includes a resilient non-metallic torque absorbing member. In still another aspect, a method of coupling a frame of an automobile to a rear wheel of the automobile includes connecting a rigid hollow frame beam to the frame and disposing a resilient cartridge in the frame beam. A first end of a rigid elongated suspension arm is coupled to the rear wheel. Furthermore, the method includes connecting an arm shaft to the suβpenβion arm βuch that arm shaft iβ diβtanced from the first end of the βuβpenβion arm. Then, the arm shaft is embedded in the resilient cartridge to substantially prevent relative motion therebetween to thereby attenuate rotational motion of the arm shaft relative to the cartridge. The details of the preβent invention, both as to its structure and operation, can beet be understood in reference to the accompanying drawings, in which like reference numerals refer to like partβ, and in which: Figure 1 iβ a perspective view of an automobile incorporating the novel suβpenβion system of the present invention, with the frame shown in phantom; Figure 2 iβ an exploded perspective view of the plastic body and steel frame, with the suβpenβion eyetern removed for clarity; Figure 3 iβ a perspective view of the left side components of the suspenβion system of the present invention in engagement with the frame, with portions broken away for clarity; Figure 4 is a crosβ-βectional view aβ seen along the line 4-4 in Figure 3; and Figure 5 iβ a cross-sectional view as seen along the line 5-5 in Figure 3. Referring initially to Figures 1 and 2, an automobile body 10 iβ βhown attached to a βteel automobile frame 12 for inclusion in an automobile, generally designated 100, having a motor 102 operably engaged therewith. Preferably, the automobile body 10 iβ made of a plastic composite material by injection molding. In a particularly preferred embodiment, the automobile body 10 is made of fiberglass-reinforced polyethylene (PET) plastic, such as the material that is available from Hoechst-Celaneβe under the trade name Celstran PET-15 having 15% fiberglasβ by weight. As fully disclosed in the above-referenced U.S. patent applications and shown best in Figure 2, in the preβently preferred embodiment the body 10 iβ made of four molded pieces. Specifically, the body 10 is made of unitarily molded inner left and right panels 14, 16 which are bonded together. Also, the body 10 is made of unitarily molded outer left and right panels 18, 20 which are bonded to their respective inner panels 14, 16. Aβ intended by the preβent invention, the inner and outer left panels 14, 18 establish a relatively βtiff molded left βhell, while the inner and outer right panels 16, 20 establish a relatively stiff molded right shell. Each of the outer panels 16, 20 is formed with a respective lower engagement lip 22, 24, and as more fully disclosed below each lip 22, 24 is adhesively bonded to the frame 12. In addition to bonding the body 10 to the frame 12, the adhesive also reduces the transmission of unwanted noise from the frame 12 to the body 10. Additionally, a plurality of, preferably six, steel anti-peeling bolts 26a,b, 28a,b, 30a,b hold the body 10 next to the frame 12 by engaging reβpective threaded receptacles 32-36 in the frame 12 to prevent the body 10 from peeling away from the frame 12. While Figure 2 showβ a four-piece body 10, it iβ to be understood that the preβent invention may be incorporated in automobileβ having plastic bodies configured differently from the body 10. Now referring to Figure 3, a left rear wheel 38 of the automobile 100 is shown for reference in cooperation with the frame 12. An elongated rigid steel βuβpβnsion arm 40 is coupled to the wheel 38 and to the frame 12, as more fully disclosed below. It is to be understood that a suspenβion arm (not shown) which in all essential respects is identical to the suβpenβion arm 40 shown in Figure 3 couples the right rear wheel of the automobile 100 to the frame 12. In the specific embodiment shown, the suβpenβion arm 40 haβ a rear end segment 42 formed integrally with or welded to a generally flat, generally parallelepiped-shaped arm bracket 44, and the arm bracket 44 iβ bolted to a complementarily- configured wheel bracket 46 (shown in phantom) . In turn, the wheel bracket 46 depends downwardly from and iβ fixedly attached to or formed integrally with a wheel hub 48 (alβo shown in phantom) which circum¬ scribes a rear axle 50 of the automobile 100. It is to be understood that wheel hub 48 does not rotate with the wheel 38. Rather, the wheel hub 48 iβ engaged with a spindle (not shown) by means well-known in the auto- motive art, to prevent rotational motion of the hub 48. As shown, the βuβpenβion arm 40 iβ elongated, and extends longitudinally forward relative to the automobile 100 (i.e., in the direction indicated by the arrow 52) to terminate in a front end segment 54. Aβ shown, the suspension arm 40 may not be configured as a straight parallelepiped-shaped bar, but may inβtead be configured with a slight upward bend segment 56 if necesβary to avoid interference with other components of the automobile 100. Nevertheless, it is to be understood that the suβpenβion arm of the preβent invention, in an elemental embodiment, iβ a rigid, elongate, longitudinally-disposed suspension arm, apart from incidental configurations which may be necessary, depending on the model of the automobile 100, to clear interference with other automotive components. Thus, as intended by the present invention, the suspension arm 40 iβ different than current βuβpension springs, which have material resiliency so they can flex under load. In contraβt, the suβpenβion arm 40 substantially does not flex. Figure 3 shows that a solid steel βuβpenβion arm βhaft 58 iβ fixedly engaged with the βuβpenβion arm 40 in a perpendicular relationship therewith. Stated differently, the shaft 58 is connected to the βuβpenβion arm 40 and extends transversely away therefrom. To engage the βhaft 58 with the arm 40, an arm βegment 58a of the βhaft 58 iβ splined, i.e., the arm βegment 58a is not round. In cross-reference to Figures 3, 4, and 5, the arm segment 58a iβ somewhat square-shaped in transverse (with respect to the βhaft 58) cross-section, with the vertices of the square being gently rounded, although other spline configurations may be uβed. In any case, the suspension arm 40 is formed with a receptacle cavity 60 (best shown in Figure 5) that iβ configured for closely receiving the splined arm segment 58a of the arm βhaft 58 therein. Additionally, a pinch bolt 62 may be threadably engaged with the βuβpenβion arm 40 and rotated to urge tightly againβt the arm βegment 58a, to further engage the arm βegment 58a with the βuβpenβion arm 40. Referring back to Figures 3 and 4, the frame 12 includes a rigid steel longitudinal beam 64 and a rigid hollow βteel transverse beam 66. As can be appreciated in reference to Figure 3, the beams 64, 66 of the frame 12 are fixedly coupled together, e.g., by welding the beams together. An elongated resilient rubber cartridge 68 is press-fit into the transverse beam 66. In accordance with the preβent invention, the cartridge 68 establishes a resilient non-metallic torque absorbing member. In one presently preferred embodiment, the cartridge 68 is made of a type ASTM specification M4AA624A13B13F17Z1 natural rubber made by Goodyear Tire Co. In the embodiment shown, the cartridge 68 iβ hexagonally-shaped in tranβverβe (with reβpect to the cartridge 68) cross-section. Accordingly, the transverse beam 66 is formed with a hexagonally-βhaped channel 70 for closely receiving the cartridge 68 therein, while the outer surface of the tranβverβe beam 66 iβ square. If desired, the outer surface of the transverse beam 66 can also be hexagonally-shaped. It is to be understood, however, that cartridge shapes other than hexagonal may be uβed. Figure 4 shows the dimensions of the cartridge 68. As shown, the cartridge 68 has a length "L" of about fourteen inches (14") . Also, the distance "W" between opposing faces of the cartridge 68 is about three and a half inches (3.5"). As shown in Figure 3 and 4, a solid cylindrical cartridge segment 58b of the arm shaft 58 iβ embedded in and extends centrally through the cartridge 68. Effectively, the cartridge βegment 58b pivotably engages the suβpenβion arm 40 with the cartridge 68. To tightly bond the cartridge βegment 58b to the cartridge 68, the cartridge βegment 58b iβ vulcanized to the cartridge 68. In the preβently preferred embodiment, the cartridge βegment 58b haβ a diameter "D" of about one and a half incheβ (1.5"). With the above disclosure in mind, it may now be appreciated that relative rotational motion between the arm shaft 58 and cartridge 68 iβ substantially prevented. It may be further appreciated that when the wheel 38 moveβ up-and-down relative to the automobile 100 (i.e., in the directionβ indicated by the arrow 72) , aβ typically occure during driving, thiβ motion is transferred via the suβpenβion arm 40 to the arm shaft 58. In turn, the cartridge segment 58b of the arm shaft 58 iβ urged to rotate, but owing to the vulcanized bond between the βegment 58b and the resilient cartridge 68, and the material resiliency of the cartridge 68, rotational motion of the arm βhaft 58 (and, hence, up-and-down motion of the βuβpenβion arm 40 and wheel 38) iβ attenuated. If desired, lateral movement of the suβpenβion arm 40 (i.e., in the direction indicated by the arrow 74) can be limited by a mechanical stop. In the embodiment shown in Figure 3, a left end face 76 establishes such a mechanical stop, to limit inboard lateral movement of the suspension arm 40. Other structure may be used, however, to perform the same function, depending on the particular configuration of the frame 12. For example, a metallic stop (not shown) may be welded to the frame 12 to limit lateral movement of the suspension arm 40. Outboard lateral movement of the suβpenβion arm 40 can be similarly limited by a mechanical stop. Figure 3 best showβ that a βhock bracket 78 iβ formed integrally with or welded to the forward end segment 54 of the suβpenβion arm 40. λβ shown, the shock bracket 78 preferably includes two bracket rails 78a, 78b. An elongated, longitudinally-oriented (with respect to the automobile 100) pneumatic automotive shock absorber 80 has a rear mount 82 connected to the shock bracket 78 by means well-known in the art. In the specific embodiment shown, the rear mount 82 of the βhock absorber 80 iβ established by a rod 84 of the shock absorber 80, and the rod 84 iβ engaged with a pin 86 which in turn iβ coupled to the railβ 78a,b of the shock bracket 78 by means well-known in the art. Additionally, a cylinder 88 of the shock absorber 80 establishes a front mount of the shock absorber 80 which iβ connected to the frame 12 by connection means well-known in the art such that the βhock absorber 80 is mounted substantially horizontally on the automobile 100. In the embodiment shown, a threaded shaft 90 extends forwardly from the cylinder 88 and through a frame bracket 92 that is fixed, as by welding, to the longitudinal beam 64 of the frame 12. A nut 94 is engaged with the shaft 90 and is tightened against the frame bracket 92 to couple the shock absorber 80 to the frame 12. Accordingly, as shown the βhock absorber 80 of the present invention is not oriented subβtantially vertically relative the automobile 100, nor is the shock absorber 80 connected directly to the body 10 of the automobile 100, in contraβt to conventional βhock absorber arrangements. Instead, the shock absorber 80 iβ oriented substantially longitudinally and horizontally relative to the automobile 100, and iβ connected directly to the frame 12 inβtead of the body 10. Consequently, the force loading of the shock absorber 80 is diβtributed to the frame 12, and stress to the plastic body 10 induced by the suspenβion βyβtem of the automobile 100 iβ thereby avoided. Moreover, interior βpace in the automobile 100 iβ maximized by the disclosed arrangement. In the embodiment shown, the βhock absorber 80 iβ canted slightly downwardly and inboard from its rear mount to its front mount to avoid interference with other components of the automobile 100. It iβ to be understood that other slight variations in the orientation of the βhock absorber 80 may be effected to avoid interference. Nonetheless, the shock absorber 80 of the present invention is mounted subβtantially fore- and-aft relative to the automobile 100, and iβ connected to the frame 12. In one presently preferred embodiment, the shock absorber 80 is a type X68565 Monroe βhock absorber.

Claims: C L A I M S 1. A suβpenβion system for a motor vehicle having a frame and a rear wheel, comprising: a rigid hollow frame beam connected to the frame; a resilient cartridge disposed in the frame beam; a rigid suspenβion arm having a first end coupled to the rear wheel; an arm shaft connected to the suspension arm and distanced from the first end of the βuβpenβion arm, the arm shaft being embedded in the resilient cartridge and engaged therewith to substantially prevent relative motion therebetween to thereby attenuate rotational motion of the arm shaft relative to the cartridge. 2. The βuβpenβion βyβtem of claim 1, wherein the frame beam extends transversely across the motor vehicle. 3. The suβpenβion βyβtem of claim 2, wherein the resilient cartridge defines a hexagonal cross section having a distance between opposed sides of approximately three and one-half inches (3.5"), the cartridge being made of rubber. 4. The βuβpenβion βyβtem of claim 3, wherein the arm βhaft is splined to the βuβpenβion arm. 5. The βuβpenβion system of claim 4, wherein the resilient cartridge is press fit into the frame beam. 6. The suβpenβion βyβtem of claim 5, wherein the arm βhaft is bonded to the resilient cartridge by vulcanizatio . 7. The suspenβion system of claim 5, wherein the arm shaft extends through the cartridge. 8. An apparatus, compriβing: an automobile including a plastic molded body, a rear wheel, and a frame; and a suβpenβion βyβtem coupling the rear wheel to the frame, the βuβpenβion βyβtem including a resilient non-metallic torque absorbing member. 9. The apparatus of claim 8, wherein the frame includes a hollow frame beam, and the resilient non- metallic torque absorbing member is a resilient cartridge diβpoββd in the frame beam. 10. The apparatus of claim 9, wherein the suβpenβion βyβtem compriβeβ: a rigid elongated βuβpenβion arm having a first end coupled to the rear wheel; an arm shaft connected to the suβpenβion arm and diβtanced from the firβt end of the βuβpenβion arm, the arm βhaft being embedded in the reβilient cartridge and engaged therewith to βubβtantially prevent relative motion therebetween to thereby attenuate rotational motion of the arm βhaft relative to the cartridge. 11. The apparatus of claim 10, wherein the frame beam extends transverβely across the motor vehicle, and the arm βhaft iβ βplined to the βuβpenβion arm and bonded to the reβilient cartridge by vulcanization, the arm βhaft extending through the cartridge. 12. The apparatus of claim 11, wherein the resilient cartridge defines a hexagonal cross section with opposed sides spaced by about three and a half inches (3.5"), the cartridge is made of rubber, and the cartridge is press fit into the frame beam. 13. A method of coupling a frame of an automobile to a rear wheel of the automobile, comprising: connecting a rigid hollow frame beam to the frame; disposing a resilient cartridge in the frame beam; coupling a firβt end of a rigid elongated βuβpenβion arm to the rear wheel; connecting an arm βhaft to the βuβpenβion arm βuch that arm βhaft iβ diβtanced from the firβt end of the βuβpenβion arm; and embedding the arm βhaft in the reβilient cartridge to βubβtantially prevent relative motion therebetween to thereby attenuate rotational motion of the arm βhaft relative to the cartridge.

Inventors: CRUISE PHILLIP D, RICH JAMES C, CRUISE, PHILLIP, D., RICH, JAMES, C.
Applicants: CHRYSLER CORP, CHRYSLER CORPORATION
Application year: 1996
Main classification: B60G
IPC codes: B60G7, B60G11, B60G13, B62D65