Patent Application
20120038126
1. Field of Invention
The invention relates, generally, to a swing arm for a vehicle suspension and, in particular, to a swing arm for a vehicle front suspension as well as a method for manufacturing such an arm.
2. Description of Related Art
A swing arm of the above-indicated type is known from European Patent EP0794075B1. According to this known solution, the swing arm is obtained by stamping from a single sheet metal piece including a main portion which has an open section and secondary portions which have a closed section and are arranged along edge zones of the arm. The swing arm known from the aforesaid patent is manufactured by folding of the edge zones of the arm substantially along the whole perimeter of the same, with the exception of the zone of mounting of the wheel and of the zone of connection to the vehicle body, as well as of the zone of bifurcation of the transversely inner arm portion, which causes an increase in the cost of the arm, in addition to an increase in the weight of the arm with respect to an open-section stamped arm.
It is therefore an object of the invention to provide a swing arm for a vehicle suspension which makes it possible to reach a good compromise between the need for reducing the manufacturing costs and the weight of the arm and the need for ensuring a high stiffness of the arm.
The invention overcomes the disadvantages in the related art in a swing arm for a suspension of a vehicle. The swing arm comprises a substantially transversely outer arm portion having a free end for mounting of a support for supporting a wheel of the vehicle and a substantially transversely inner arm portion with a first branch and second branch. The first branch is substantially aligned with the outer arm portion and has a free end for mounting of a first connector for connection to a body of the vehicle, and the second branch extends along an arched path towards a rear part of the vehicle and has a free end for mounting of a second connector for connection to the vehicle body. A single-sheet metal piece includes a main portion having an open section and at least one secondary portion arranged in an edge zone of the swing arm, having a closed section, and formed by at least one strip of the metal piece folded onto the main portion and firmly secured with a free edge of the strip to the main portion.
The invention overcomes the disadvantages in the related art also in a method for manufacturing the swing arm. The method comprises steps of obtaining the main portion by stamping of the metal piece, folding the strip of the metal piece so as to obtain the secondary portion, and firmly securing the free edge of the strip to the main portion.
The invention is based on the idea of providing a swing arm for a vehicle suspension, in particular for a front suspension, in which at least one secondary arm portion having a closed section is obtained by folding and firmly securing, such as by welding, a strip of sheet metal to the remaining main arm portion having an open section. A reinforcement is thus obtained which is located in the zone(s) of the arm where it is necessary to increase the stiffness and the mechanical strength, thereby minimizing the overall cost and weight of the arm.
In an embodiment, the secondary portion having a closed section is located along a length of the edge of the arm extending close to a through hole provided in a central zone of the arm. The secondary portion having a closed section can, however, be located in any other point of the edge of the arm. Moreover, many secondary portions having a closed section may be provided.
In an embodiment, the outline of the cross-section of the main portion having an open section comprises a pair of horizontal straight lengths at the opposite ends of the section, a pair of vertical straight lengths extending from the opposite ends of the two horizontal straight lengths, and a U-shaped middle length which extends between the two horizontal straight lengths and includes a bottom and a pair of vertical sides. The free edge of the folded strip of sheet metal is firmly secured to either of the vertical sides of the U-shaped middle length of the main arm portion.
Other objects, features, and advantages of the invention will be readily appreciated as the invention becomes better understood while reading the subsequent detailed description of the invention taken in conjunction with the accompanying drawing thereof.
In the following description and claims, terms such as “longitudinal” and “transverse,” “inner” and “outer,” and “front” and “rear” are referred to the mounted condition of the swing arm on the vehicle—in particular, to the mounted condition of the swing arm as a component of the front suspension of the vehicle.
With reference first to
The swing arm 10 includes a single sheet metal piece which is obtained by stamping and includes a main portion 30 having an open section and at least one (exactly one in the embodiment illustrated in the drawing) secondary portion 32 having a closed section. The secondary portion is located in an edge zone of the swing arm 10.
The outline of the open-section main portion 30 of the swing arm 10 is suitably shaped to provide the swing arm 10 with a sufficient stiffness—in particular, under bending. For instance, in both the embodiments shown in
The closed-section secondary portion 32 of the swing arm 10, which in the drawing is the edge zone of the second branch 20 of the transversely inner arm portion 16 located close to the hole 28, has the function of providing the arm with the required mechanical properties in terms of fatigue life, stiffness, and resistance to deformation in case of impact. The closed-section secondary portion 32 is obtained by folding of a strip 34 of the single sheet metal piece which extends from the free edge of a vertical straight length 30b of the open-section main portion 30. The strip 34 may be a simple flat (or approximately flat) strip or, as in the embodiment illustrated in
Naturally, the closed-section secondary portion may be located in any other zone of the arm depending on the required characteristics. In any case, the closed-section secondary portion does not extend along the whole perimeter of the arm or along the largest part of the perimeter of the arm (as in the known swing arm), but only along a restricted portion thereof, whereby the increase in cost and weight with respect to a traditional arm having an open section is minimized. Many secondary portions having a closed section of the type of the one described above may also be provided, these portions extending only along a minimum part of the perimeter of the arm.
The material used for producing the swing arm according to the invention can be a high-strength steel, i.e., a steel having a high-yield strength, but it is also possible to use other materials particularly suitable for cold-stamping or hot-stamping followed by hardening and tempering. For example, the following materials can be used: low-alloy steels, boron steels, and vanadium steels.
A method for manufacturing the swing arm according to the invention comprises steps of:
obtaining by stamping of a single piece of sheet metal an arm with an open section integrally forming a transversely outer arm portion and transversely inner arm portion having a first branch and second branch bifurcating from the transversely outer arm portion;
folding or bending at least one strip of sheet metal of the arm so as to obtain a closed section located in an edge zone of the arm; and
securing—for instance, by welding—the free edge of the strip (or strips) of sheet metal of the arm to the remaining open-section part of the arm.
The invention has been described above in an illustrative manner. It is to be understood that the terminology that has been used above is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the invention may be practiced other than as specifically described above.
| Number | Date | Country | Kind |
|---|---|---|---|
| TO2009A000076 | Feb 2009 | IT | national |
This application claims benefit of PCT Patent Application PCT/IB2010/050513 entitled “Suspension Arm for a Motor Vehicle Wheel Suspension” and filed on Feb. 4, 2010, which claims benefit of Italian Patent Application TO2009A000076 filed on Feb. 5, 2009.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/IB2010/050513 | 2/4/2010 | WO | 00 | 8/4/2011 |
