Patent Application
20140251059
The following description relates to energy absorbing devices, and more particularly, to energy absorbing straps for a steering column assembly.
Roll strap devices have been used as a means to absorb energy during the collapse of a steering column. Typically, roll straps absorb energy during the deformation of the strap in crash event. For example, a vehicle operator may contact the steering column assembly, whereby kinetic energy of the occupants may be dissipated through compression of the steering column assembly. However, it may be advantageous to improve control of the collapse characteristics of some known roll strap devices.
Accordingly, it is desirable to provide systems and methods for controlling or tuning the characteristics of a roll strap to provide a desired kinetic energy dissipation of vehicle occupants in the event of contact between a vehicle occupant and a steering column assembly.
In an exemplary embodiment of the invention, an energy absorbing device for a steering column assembly is provided. The device includes a first end configured to couple to a first component of the steering column assembly, a second end configured to couple to a second component of the steering column, and an intermediate portion extending between the first and second ends. The intermediate portion includes a curved portion having a radius, and an aperture extending through the intermediate portion. The aperture is configured to shift a collapse characteristic of the energy absorbing device and to facilitate maintaining the radius constant when a force moves the first end relative to the second end and deforms the energy absorbing device.
In another exemplary embodiment of the invention, a steering column assembly is provided. The assembly includes a mounting bracket, a first jacket coupled to the mounting bracket and having a longitudinal axis, and a second jacket slidably disposed with the first jacket for telescoping movement along the longitudinal axis relative to the first jacket. The assembly further includes an energy absorbing strap having a first end coupled to the second jacket, a second end coupled to one of the first jacket and the mounting bracket, and an intermediate portion extending between the first and second ends. The intermediate portion includes a curved portion having a radius, and an aperture extending through the intermediate portion. The aperture is configured to shift a collapse characteristic of the energy absorbing device and to facilitate maintaining the radius constant when a force moves the first end relative to the second end and deforms the energy absorbing device.
In yet another exemplary embodiment of the invention, a method of fabricating an energy absorbing device for a steering column assembly is provided. The method includes providing a strap having a first end configured to couple to a first component of the steering column, a second end configured to couple to a second component of the steering column, and an intermediate portion extending between the first and second ends, where the intermediate portion includes a curved portion having a radius. The method further includes forming an aperture through the intermediate portion, the aperture configured to shift an initial collapse characteristic of the energy absorbing device and to facilitate maintaining the radius constant when a force acting on the steering column first component moves the first end relative to the second end and deforms the energy absorbing device.
These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.
The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
Referring now to the Figures, where the invention will be described with reference to specific embodiments, without limiting same,
With further reference to
In the exemplary embodiment, energy absorbing strap 30 includes a first end 32, a second end 34, and an intermediate portion 36 extending therebetween. First end 32 is coupled to upper jacket 18 by a fastener 38, and second end 34 is coupled to lower jacket 12 by a fastener 40. Alternatively, first and second ends 32, 34 may be coupled to their respective steering column components using any suitable method that enables assembly 10 to function as described herein. For example, first and second ends 32, 34 may be welded to upper jacket 18 and mounting bracket 16, respectively.
Strap intermediate portion 36 includes a curved portion 42 having a radius ‘R’. Curved portion 42 facilitates “rolling” of strap 30 during a collapse event as first end 32 moves in the direction of force ‘Fx’. An initial collapse or roll area 44 is located at the transition between curved portion 42 and a flat portion 46 of intermediate portion 36. Initial collapse area 44 represents the starting roll or deformation location where the “roll” or deformation of strap 30 begins during a collapse event.
In the exemplary embodiment, energy absorbing strap 30 includes an inner wall 48 defining an aperture 50 that extends through intermediate portion 36. Aperture 50 facilitates controlling or tuning initial collapse characteristics of energy absorbing strap 30. In the embodiment shown in
Slot first end 54 is located at or in proximity to starting roll location 44 and, as illustrated in
The collapse characteristics of strap 30 are further influenced or tuned by the position of slot first end 54 in relation to starting roll location 44. With further reference to
Additionally, the collapse characteristics of strap 30 can be tuned or adjusted by varying other attributes of aperture 50 and strap 30. For example, a slot width ‘w’ 52 may be increased or decreased to respectively drop or raise the load required to initiate collapse, a thickness ‘t’ of strap 30 may be increased or decreased to respectively raise or drop the load required to initiate collapse, and/or radius ‘R’ may be increased or decreased to respectively drop or raise the load required to initiate collapse.
Accordingly, the load profile of strap 30 is influenced by direct variation of parameters of strap 30, and the amount of roll radius expansion is influenced after the start of collapse movement at least in part by the rigidity between applied force ‘Fx’ and the position of roll radius ‘R’ (i.e., how the strap is secured to jackets 12, 18).
In the exemplary embodiment, when a force acts upon steering column assembly 10 (e.g., an occupant impacting the steering wheel), particularly along longitudinal axis 14, upper jacket 18 is pushed toward lower jacket 12. Because strap second end 56 is coupled to a fixed component of assembly 10 or the vehicle (e.g., lower jacket 12), as upper jacket 18 is forced toward lower jacket 12, strap second end 56 is held in place while energy absorbing strap 30 is rolled in the direction of force ‘Fx’. As energy absorbing strap 30 rolls, roll radius ‘R’ is repositioned along strap 30 and energy is absorbed by the deformation of energy absorbing strap 30. As such, upper jacket 18 at least partially collapses onto lower jacket 12, thereby dissipating the kinetic energy of an occupant or object colliding with steering column assembly 10.
While energy absorbing straps 30, 130, and 230 are described coupled to specific components of a steering column assembly, it should be noted that an energy absorbing strap according to the present invention can have various configurations and will function as described herein when one strap end is coupled to a fixed portion of a vehicle/column (e.g., a vehicle cross-car beam) and the other strap end is coupled to a steering column component that moves during a collapse event (e.g., an upper jacket).
Systems and methods to control and tune collapse characteristics of energy absorbing straps are described herein. By removing strap material to form an aperture in proximity of the starting roll position, the strap energy absorbing load profile can be purposefully influenced. Various aperture cross-sectional geometries and strap attachment configurations can be implemented between the applied force ‘Fx’ and the roll radius ‘R’. Benefits of these exemplary embodiments of the invention include increased flexibility in the energy absorbing load curve control for roll strap designs, and simplicity of production tooling.
While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description.
This patent application claims priority to U.S. Provisional Patent Application Ser. No. 61/774,890, filed Mar. 8, 2013, which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61774890 | Mar 2013 | US |
