Patent Application
20070257462
The present invention relates generally to a vehicle suspension system and, more particularly, to a stabilizer bar for dampening the roll of a vehicle.
Vehicles are commonly equipped with suspension systems having a stabilizer bar that increases roll rigidity and improves steering stability of the vehicle. Typically, the stabilizer bar is a rod-shaped member that extends laterally across the vehicle. The stabilizer bar includes a central section and an arm segment that extends longitudinally at each end of the central section. An end link couples the end of each arm segment to a control arm of the suspension system.
Typically, a connection feature is used to secure the arm segments to the end links. One type of connection feature includes a ball stud and socket that are commonly manufactured as separate units from the stabilizer bar. The ball stud is secured with a fastener, such as a bolt, through an eye of a mounting portion of the arm segment. The socket is secured to a portion of the end link and receives the ball stud to secure the arm segment to the end link.
There are several disadvantages with such an arrangement. For one, the fasteners can interfere with movement of the end link. Further, the mounting portions and eyes of the arm segments are typically formed in a forging process and secondarily forged or machined to meet dimensional requirements. The secondary forming process adds complexity and expense to the manufacturing process. Additionally, because the ball studs are typically manufactured independently and are fastened to the stabilizer bar, multiple machine operations are necessary and substantial weight is added to the suspension system.
Accordingly, there is a need for a simplified stabilizer bar that can be manufactured economically. This invention addresses those needs and provides enhanced capabilities while avoiding the shortcomings and drawbacks of the prior art.
One example method for forming a stabilizer bar includes the steps of providing a metal bar having first and second ends, and die casting first and second receptacles over the respective first and second ends.
One example stabilizer bar for use in a vehicle suspension system includes a metal bar having first and second ends, and first and second die cast receptacles that are respectively formed over the first and second ends.
The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows.
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In one example, the metal bar 26 is manufactured from spring steel and the receptacle 28 is also made of steel, but not necessarily spring steel. In one example, using similar materials for the metal bar 26 and the receptacle 28 promotes bonding therebetween because the similar materials form a strong bond. However, in another example, the receptacles 28 and metal bar 26 are made of dissimilar metals. In one example, the receptacles 28 are made of a non-ferrous metal, such as a zinc alloy, an aluminum alloy, or other non-ferrous material. These materials provide the advantage of lighter weight compared to steel.
In the illustrated example, the end section 46b forms an angle α with the base section 46a. The angle α, other desired angles, curvatures or the like, can be pre-designed into the receptacle 28. This allows bends or curves near the ends of the metal bar 26 to be eliminated, thereby eliminating additional steps and expense in forming the metal bar 26.
In the illustrated example, die casting the receptacle 28 over the ends of the metal bar 26 provides the benefit of forming the surfaces 50a and 50b parallel to each other within a desired tolerance. Parallel surfaces 50a and 50b allow uniform distribution of the stress exerted on the receptacle 28 from tightening of the nut 56 and washers 58 on the fastener 52. Prior assemblies having receptacles that are, for example, formed by forging are unable to achieve the degree of tolerance that is possible with die casting without utilizing a secondary forming process. Thus, the die cast receptacle 28 provides flatter surfaces 50a and 50b for enhanced stress distribution without the need for a secondary forming process.
The metal bar 26 in the illustrated embodiment is hollow such that a passage 60 extends through the metal bar 26. Before the die casting step 42, a plug 62 is inserted within the passage 60 at each end of the metal bar 26 to prevent molten die cast material from flowing through the passage 60 during formation of the receptacles 28. The plug 62 also provides the benefit of sealing the metal bar 26 (in addition to the receptacles 28) to prevent environmental elements, such as road water, from infiltrating the passage 60 and corroding the metal bar 26 from the inside.
The disclosed examples illustrate receptacles 28 that are die cast over the ends of the metal bar 26. Die casting the receptacles 28 provides the benefit of achieving dimensional tolerances that are difficult or impossible to achieve with previously used methods, such as forging. Thus, with die casting, secondary machining operations may be eliminated in many cases. Furthermore, die casting provides a stabilizer bar 18 having integral receptacles 28. This eliminates the need for fasteners or the like in some examples, which reduces cost and the number of parts in the assembly.
Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.
