Land vehicles: bodies and tops – Bodies – Structural detail
Reexamination Certificate
1999-05-18
2001-01-23
Pedder, Dennis H. (Department: 3612)
Land vehicles: bodies and tops
Bodies
Structural detail
C296S072000, C280S779000, C280S752000
Reexamination Certificate
active
06176544
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an instrument panel reinforcement structure for motor vehicles. The reinforcement structure extends between two front pillars and supports a steering column, a glove box, a passenger side air bag and various other instrument panel components.
BACKGROUND OF THE INVENTION
The instrument panel reinforcement structure is the part of a motor vehicle extending between left and right front pillars in front of the passenger compartment. Various components mounted on the instrument panel reinforcement structure include the steering column assembly, a glove box, a passenger side air bag, an instrument cluster, an entertainment/information system, a heating/ventilation/air conditioning unit with associated ducts, a wire harness, electrical modules and fascia. The inclusion of driver side air bags and the locating of some controls in the steering column assembly have caused it to gain weight and to grow in size.
Passenger vehicles have been made safer in recent years through the use of safety devices such as seat belts and air bags. In addition, automobile manufacturers are making the body and its associated components more energy absorbent in the event of a collision. The United States government has also established a set of Motor Vehicle Safety Standards mandating certain other minimum vehicle safety requirements.
In the prior art, some attempts have been made to provide instrument panel structural reinforcement assemblies for motor vehicles. However, the prior art assemblies generally suffer from one or more serious disadvantages making them less than entirely suitable for their intended purpose. For example, steel assemblies have been used for some time but they add considerable weight to vehicle bodies. Accordingly, there is a need for an alternative to steel instrument panel assemblies.
Onitsuka U.S. Pat. No. 4,560,186 describes an automobile instrument panel assembly supported by a reinforcement
4
comprising a pipe
5
extending between two pillars
3
. The pipe has a uniform size in the cross-car direction. A steering column mounting bracket made up of metal sheets is welded to the pipe
5
on the right (driver's) side. Onitsuka's assembly is difficult to manufacture economically because it includes so many individual parts welded to the pipe
5
. Accordingly, there still remains a need for a stiff, light weight, economically manufacturable instrument panel reinforcement structure.
A principal objective of our invention is to provide a light weight instrument panel reinforcement structure for motor vehicles that has enhanced structural stiffness in order to minimize steering column vibrations.
A related objective of the present invention is to provide an instrument panel reinforcement structure for motor vehicles made from aluminum alloy and magnesium alloy components. The reinforcement structure of the present invention offers about a 40% weight saving compared with similar systems having steel components. The preferred reinforcement structure shown and described herein weighs only about 18 pounds (7.7 kg).
Another objective of the invention is to provide a light weight instrument panel reinforcement structure that consumes little additional cockpit space and is inexpensive to manufacture and to install on a mass production assembly line.
A further objective of our invention is to provide an instrument panel reinforcement structure that adapts easily to left and right hand drive cars and accommodates different steering column orientations.
One important advantage of our invention is that it has a common base structure adaptable to a variety of different designs by addition or swapping of components, thereby reducing effort, time and cost required for engineering the instrument panel structural system.
Additional objectives and advantages of our invention will become apparent to persons skilled in the art from the following detailed description.
SUMMARY OF THE INVENTION
In accordance with the present invention there is provided a light weight instrument panel reinforcement structure for inclusion in a motor vehicle body having a floor panel and several pillars extending upwardly from the floor panel. The reinforcement structure extends between the left and right front pillars in front of the passenger compartment. The reinforcement structure supports a steering column, a glove box, a passenger side air bag and various other instrument panel components.
A preferred instrument panel reinforcement structure comprises a passenger side cross tube and a driver side cross tube connected by a center stack support. The cross tubes are preferably connected to the front pillars through metal brackets. The center stack support is preferably connected to the floor panel. Mounting tubes attached to the driver side cross tube support the steering column. The passenger side air bag support is attached to the passenger side cross tube. A driver side knee bolster is connected to the driver side cross tube through metal crush tubes. Metal crush tubes also connect a glove box door frame to the passenger side cross tube.
The driver side cross tube and the passenger side cross tube are preferably aluminum alloy extrusions. Aluminum alloys of the Aluminum Association (AA) 6000 series are preferred although other alloys may also be used. The AA 6000 alloys including AA5000 series alloys generally contain about 0.2-2 wt. % silicon and about 0.2-2 wt. % magnesium. These aluminum alloys usually also contain other alloying elements and some impurities. Our particularly preferred cross tubes are made with an AA 6063 T4 alloy containing about 0.2-0.6 wt. % Si, 0.45-0.9 wt. % Mg, 0.35 wt. % max. Fe, 0.10 wt. % max. Cu, Cr, Zn and Ti, remainder Al, incidental elements and impurities.
A particularly preferred driver side cross tube is extruded as a hollow oval having a 120×60 mm cross-section with an average 5 mm wall thickness. The extruded cross tube is hydroformed in a middle portion to provide a generally triangular cross section with a flat bottom surface appropriately oriented for attachment of two steeling column support tubes. The cross tube also includes two openings for crush tubes contacting a driver side knee bolster. The steering column support tubes are preferably AA 6063-T4 aluminum alloy extrusions having a wall thickness of about 5 mm. A particularly preferred passenger side cross tube is a hollow cylinder having an outer diameter of about 60 mm and a wall thickness of about 3 mm. The driver side cross tube and the passenger side cross tube both extend laterally or in a cross-car direction, on opposite sides of a center stack support. An important feature of our invention is that the driver side cross tube has greater average wall thickness than the driver side cross tube. outwardly of the center stack support and a first wall having a thickness that is generally constant across the first length. The driver side cross tube has a second length extending laterally outwardly of the center stack support and a second wall having a thickness t
2
that is generally constant across the second length.
The driver side cross tube is preferably reformed by a process that includes pressurizing the tube internally with an incompressible fluid at sufficient pressure to deform the middle portion inside a die. The incompressible fluid is preferably water at a pressure of about 100-5,000 psi, more preferably about 1,000-3,000 psi. A die outside the middle portion and the pressurized water force the middle portion into a generally triangular cross section while the end portions retain their original, oval cross-sectional shape. The hydroformed driver side cross tube still has continuous internal and external surfaces.
The generally triangular middle portion has a larger radius of gyration than the end portions. Accordingly, the driver side cross tube has excellent resistance to twisting, even after a steering column is attached. The triangular middle portion also has greater resistance to vibration than the end portions.
The center stack su
Cobes John W.
Michael Richard A.
Seksaria Dinesh C.
Alcoa Inc.
Klepac Glenn E.
Pedder Dennis H.
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