SUSPENSION SYSTEM

Abstract: An automobile includes a plastic body and a steel frame (12) bonded to the plastic body. The rear suspension system of the automobile includes a suspension arm (40) coupled to a rear wheel (38). An arm shaft (58b) extends transversely inwardly from the suspension arm and is embedded in a rubber cartridge (68) press-fit into the frame, to thereby attenuate motion of the suspension arm. A horizontally-mounted longitudinally-oriented shock absorber (80) 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 iβ 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. λs further recognized by the present invention, by inaking an automobile body of lightweight molded plastic, 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, aβ recognized herein the load of the shock absorbers on the plastic body, were the shock abβorberβ to be connected directly to the body, could crack and otherwise damage the body. Simply reinforcing the plaβtic body to βupport the βhock 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 uβe. Accordingly, it iβ one intent of the present invention to βupport suspension eyetern βhock abβorberβ with βtructure other than the automobile body. It iβ 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 iβ to provide a suspension system for a lightweight automobile in which shock abβorberβ are not connected directly to the body of the automobile. Yet another object of the preβent invention iβ to provide a suspension system for a lightweight automobile that is easy to use and cost-effective to manufacture. A βuβpenβion system for an automobile which includes a rear wheel and a plastic body attached to a steel frame includes a suspension arm coupled to the wheel. The βuβpenβion system further includeβ an elongated βhock abβorber having a rear end connected to the βuβpenβion arm and a front end connected to the frame, with the βhock abβorber being oriented substantially horizontally. Moreover, the shock abβorber is oriented substantially fore-and-aft with respect to the vehicle. In a preferred embodiment, the suspension arm has a forward end connected to the βhock abβorber and a rear end connected to the wheel. In thiβ embodiment, the βuβpenβion system includeβ a rigid hollow frame beam connected to the frame and a resilient cartridge dispoβed in the frame beam. An arm shaft is connected to the βuβpenβion arm, preferably by βplining, near the βhock abβorber and distanced from the rear end of the suspension arm. Additionally, this arm shaft is embedded in the resilient cartridge and iβ engaged therewith to attenuate rotational motion of the arm shaft relative to the cartridge. Preferably, the resilient cartridge is press fit into the frame beam, and the arm shaft is bonded to the resilient cartridge by vulcanization. In another aspect of the present invention, an apparatuβ includeβ an automobile having a plastic molded body, a rear wheel, and a frame. A suspension system couples the rear wheel to the frame. In accordance with the preβent invention, the βuβpenβion system includeβ a subβtantially horizontally diβpoβed βhock abβorber coupled to the rear wheel and connected directly to the frame. In yet another aspect of the preβent invention, a method of coupling a frame of an automobile to a rear wheel of the automobile includes coupling a rear end of a βhock abβorber to the rear wheel. Aβ disclosed in detail below, the shock absorber iβ oriented substantially horizontally and directly attached to the frame. The details of the present invention, both as to its structure and operation, can best be understood in reference to the accompanying drawings, in which like reference numerals refer to like parts, and in which: Figure 1 is a perspective view of an automobile incorporating the novel βuβpenβion βyβtem of the present invention, with the frame shown in phantom; Figure 2 is an exploded perβpective view of the plastic body and steel frame, with the suspension system removed for clarity; Figure 3 iβ a perβpective view of the left βide componentβ of the βuβpenβion βyβtem of the present invention in engagement with the frame, with portions broken away for clarity; Figure 4 iβ a cross-sectional view as 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 shown attached to a steel 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 aβ the material that is available from Hoechβt-Celaneβe under the trade name Celβtran PET-15 having 15% fiberglass by weight. As fully disclosed in the above-referenced U.S. patent applications and βhown beet in Figure 2, in the preβently preferred embodiment the body 10 iβ made of four molded pieces. Specifically, the body 10 iβ made of unitarily molded inner left and right panelβ 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 panelβ 14, 16. Aβ intended by the preβent invention, the inner and outer left panelβ 14, 18 establish a relatively stiff molded left βhell, while the inner and outer right panelβ 16, 20 establish a relatively stiff molded right βhell. Each of the outer panelβ 16, 20 iβ formed with a respective lower engagement lip 22, 24, and as more fully disclosed below each lip 22, 24 iβ adhββivβly 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, βteel anti-peeling bolts 26a,b, 28a,b, 30a,b hold the body 10 next to the frame 12 by engaging respective threaded receptacles 32-36 in the frame 12 to prevent the body 10 from peeling away from the frame 12. While Figure 2 shows a four-piece body 10, it iβ to be understood that the present invention may be incorporated in automobiles 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 βteel suspension arm 40 iβ coupled to the wheel 38 and to the frame 12, aβ more fully disclosed below. It is to be understood that a βuβpenβion arm (not βhown) which in all ββsential respects is identical to the suspension arm 40 shown in Figure 3 couples the right rear wheel of the automobile 100 to the frame 12. In the βpecific embodiment shown, the βuβpenβion arm 40 hae 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 (βhown in phantom) . In turn, the wheel bracket 46 depends downwardly from and is fixedly attached to or formed integrally with a wheel hub 48 (also 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 is 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 βhown, the βuβpenβion arm 40 may not be configured aβ a straight parallelepiped-βhaped bar, but may instead be configured with a slight upward bend segment 56 if necessary to avoid interference with other components of the automobile 100. Nevertheless, it is to be understood that the suspension arm of the present invention, in an elemental embodiment, iβ a rigid, elongate, longitudinally-diβpoβed βuβpenβion arm, apart from incidental configurations which may be necessary, depending on the model of the automobile 100, to clear interference with other automotive componentβ. Thuβ, aβ intended by the preβent invention, the βuβpenβion arm 40 is different than current βuβpenβion springs, which have material resiliency βo they can flex under load. In contrast, the suβpenβion arm 40 substantially does not flex. Figure 3 shows that a solid βteel suspension arm shaft 58 is fixedly engaged with the suspension arm 40 in a perpendicular relationship therewith. Stated differently, the shaft 58 is connected to the suspension arm 40 and extends transversely away therefrom. To engage the shaft 58 with the arm 40, an arm segment 58a of the shaft 58 is splined, i.e., the arm segment 58a iβ not round. In cross-reference to Figures 3, 4, and 5, the arm segment 58a is somewhat square-shaped in transverse (with respect to the shaft 58) cross-section, with the vertices of the square being gently rounded, although other spline configurations may be used. In any case, the suβpenβion arm 40 iβ formed with a receptacle cavity 60 (beet shown in Figure 5) that is configured for closely receiving the splined arm segment 58a of the arm shaft 58 therein. Additionally, a pinch bolt 62 may be threadably engaged with the βuβpenβion arm 40 and rotated to urge tightly against the arm segment 58a, to further engage the arm segment 58a with the suspenβion arm 40. Referring back to Figures 3 and 4, the frame 12 includeβ a rigid βteel 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 preββ-fit into the transverse beam 66. In accordance with the preβent invention, the cartridge 68 eβtabliβheβ 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 βhown, the cartridge 68 iβ hexagonally-shaped in transverse (with respect to the cartridge 68) cross-section. Accordingly, the transverse beam 66 is formed with a hexagonally-shaped 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 tranβverβe beam 66 can also be hexagonally-shaped. It iβ to be understood, however, that cartridge shapes other than hexagonal may be used. Figure 4 shows the dimenβionβ of the cartridge 68. Aβ βhown, the cartridge 68 hae a length "L" of about fourteen incheβ (14") . Also, the distance " " between opposing faces of the cartridge 68 is about three and a half inches (3.5") . As βhown in Figure 3 and 4, a βolid cylindrical cartridge segment 58b of the arm shaft 58 iβ embedded in and extendβ centrally through the cartridge 68. Effectively, the cartridge segment 58b pivotably engages the suβpenβion arm 40 with the cartridge 68. To tightly bond the cartridge segment 58b to the cartridge 68, the cartridge segment 58b is vulcanized to the cartridge 68. In the presently preferred embodiment, the cartridge segment 58b has 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 is substantially prevented. It may be further appreciated that when the wheel 38 moves up-and-down relative to the automobile 100 (i.e., in the directions indicated by the arrow 72) , as typically occurs during driving, this motion iβ transferred via the βuβpenβion arm 40 to the arm shaft 58. In turn, the cartridge segment 58b of the arm βhaft 58 iβ urged to rotate, but owing to the vulcanized bond between the segment 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 suspension arm 40 and wheel 38) is attenuated. If deβired, lateral movement of the βuβpenβion arm 40 (i.e., in the direction indicated by the arrow 74) can be limited by a mechanical βtop. In the embodiment βhown in Figure 3, a left end face 76 establishes such a mechanical stop, to limit inboard lateral movement of the βuβpenβion 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 suβpenβion arm 40. Outboard lateral movement of the βuβpenβion arm 40 can be similarly limited by a mechanical stop. Figure 3 best shows that a shock bracket 78 is formed integrally with or welded to the forward end segment 54 of the suspension arm 40. Aβ βhown, the βhock bracket 78 preferably includeβ 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 βhock bracket 78 by meanβ well-known in the art. In the specific embodiment shown, the rear mount 82 of the shock absorber 80 iβ established by a rod 84 of the shock absorber 80, and the rod 84 is engaged with a pin 86 which in turn iβ coupled to the railβ 78a,b of the βhock bracket 78 by meanβ well-known in the art. In one preβently preferred embodiment, the βhock abβorber 80 iβ a type X68565 Monroe βhock abβorber. Additionally, a cylinder 88 of the βhock abβorber 80 eβtabliβheβ a front mount of the βhock absorber 80 which is connected to the frame 12 by connection means well-known in the art such that the shock absorber 80 is mounted substantially horizontally on the automobile 100. In the embodiment shown, a threaded shaft 90 extendβ forwardly from the cylinder 88 and through a frame bracket 92 that iβ fixed, aβ by welding, to the longitudinal beam 64 of the frame 12. A nut 94 iβ engaged with the βhaft 90 and iβ tightened against the frame bracket 92 to couple the βhock abβorber 80 to the frame 12. Accordingly, aβ βhown the βhock absorber 80 of the preβent invention iβ not oriented substantially vertically relative the automobile 100, nor is the βhock abβorber 80 connected directly to the body 10 of the automobile 100, in contraβt to conventional βhock abβorber arrangements. Instead, the βhock abβorber 80 iβ oriented substantially longitudinally and horizontally relative to the automobile 100, and is coupled to the rear wheel 38 by the βuβpenβion arm 40 and connected directly to the frame 12 instead of the body 10. Consequently, the force loading of the βhock abβorber 80 iβ diβtributed to the frame 12, and stress to the plastic body 10 induced by the suspension system of the automobile 100 is thereby avoided. Moreover, interior space in the automobile 100 iβ maximized by the disclosed arrangement. In the embodiment shown, the shock abβorber 80 iβ canted slightly downwardly and inboard from its rear mount to ite front mount to avoid interference with other components of the automobile 100. It is to be understood that other slight variations in the orientation of the βhock abβorber 80 may be effected to avoid interference. Nonetheleββ, the βhock abβorber 80 of the present invention is mounted substantially fore- and-aft relative to the automobile 100, and is connected to the frame 12.

Claims: C A I M S 1. A suspension system for an automobile including a rear wheel and a plastic body attached to a steel frame, comprising: a suspension arm coupled to the wheel; and an elongated shock abβorber having a rear end connected to the βuβpenβion arm and a front end connected to the frame, the βhock abβorber being oriented substantially horizontally. 2. The suspension system of claim 1, wherein the βhock absorber is oriented substantially fore-and-aft with respect to the vehicle. 3. The suspension system of claim 2, wherein the suspension arm has a forward end connected to the shock absorber and a rear end connected to the wheel, and the suspension system further comprises: a rigid hollow frame beam connected to the frame; a resilient cartridge dispoβed in the frame beam; and an arm shaft connected to the suspension arm near the βhock absorber and distanced from the rear end of the suspension 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. 4. The suβpenβion βyβtem of claim 3, wherein the resilient cartridge is press fit into the frame beam, and the arm shaft is bonded to the resilient cartridge by vulcanization, the arm βhaft extending through the cartridge. 5. An apparatuβ, compriβing: an automobile including a plaβtic molded body, a rear wheel, and a frame; and a suspension system coupling the rear wheel to the frame, the suspension system including a substantially horizontally diβpoβed βhock abβorber coupled to the rear wheel and connected directly to the frame. 6. The apparatuβ of claim 5, wherein the βhock abβorber iβ oriented substantially fore-and-aft with respect to the automobile. 7. The apparatuβ of claim 6, wherein the frame includeβ a hollow frame beam, and a resilient cartridge is press-fit in the frame beam. 8. The apparatus of claim 7, wherein the βuβpenβion βyβtem compriβeβ: a rigid elongated suspension arm having a rear end coupled to the rear wheel and a front end connected to the shock absorber; an arm βhaft connected to the βuβpenβion arm near the βhock abβorber and diβtanced from the rear 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. 9. The apparatus of claim 8, wherein the frame beam extends tranβversely across the motor vehicle, and the arm shaft is splined to the βuβpenβion arm and bonded to the resilient cartridge by vulcanization, the arm shaft extending through the cartridge. 10. A method of coupling a frame of an automobile to a rear wheel of the automobile, compriβing: coupling a rear end of a βhock abβorber to the rear wheel; orienting the βhock abβorber substantially horizontally; and directly attaching a front end of the shock abβorber to the frame. 11. The method of claim 10, further compriβing the step of orienting the shock abβorber substantially fore-and-aft relative to the automobile. 12. The method of claim 11, further compriβing the steps of: connecting a rigid hollow frame beam to the frame; dispoβing a resilient cartridge in the frame beam; coupling a first end of a rigid elongated, suspension arm to the rear wheel; connecting an arm shaft 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: B60G11
IPC codes: B60G3, B60G11