Patent Application
20080100050
1. Field of the Invention
The subject invention relates to a collapsible steering column assembly, and more specifically to an energy absorption device for the collapsible steering column assembly.
2. Description of the Prior Art
Currently, many steering column assemblies are equipped with kinetic energy absorption devices to reduce a likelihood of injury resulting from a vehicular accident. There are several different types and variations of these kinetic energy absorption devices, typically involving the deformation of a plastically deformable metal. An example of such a kinetic energy absorption device is disclosed in U.S. Pat. No. 6,523,432 to Yamamoto (the '432 patent).
The '432 patent discloses a collapsible steering column assembly comprising a steering shaft supported within a column jacket and extending along a longitudinal axis. A bracket is mounted to the column jacket, and attaches the steering column assembly to a vehicle. The bracket defines a bolt hole extending transverse to the longitudinal axis, and a slot extending from the bolt hole parallel the longitudinal axis. The slot includes a pre-determined width less than a diameter of the bolt hole. A bolt having a shank within a collar is disposed within the bolt hole so as to deform edges of the slot as a result of the steering column collapsing along the longitudinal axis during a collision event. The amount of energy absorbed by the energy absorption device disclosed in the '432 patent depends upon material properties and physical dimensions of the components of the energy absorption device, and cannot be altered once the components of the energy absorption device have been installed on the steering column.
The subject invention provides a collapsible steering column assembly for a vehicle. The assembly comprises a column jacket, and a bracket for attaching the assembly to the vehicle slideable relative to the bracket along a longitudinal axis. A plate is attached to one of the bracket and the column jacket, and defines an opening and a slot extending from the opening parallel the longitudinal axis. The slot defines a pre-determined width. A pin is coupled to one of the bracket and the column jacket and is horizontally moveable relative to the plate along the longitudinal axis during the collision event. The pin includes a diameter greater than the pre-determined width of the slot, and is transversely moveable along a transverse axis relative to the plate. The pin is moveable between a disengaged position withdrawn from the opening and an engaged position extending into the opening and engaging the slot. The pin engages the slot in response to the horizontal movement of the plate relative to the pin.
Accordingly, the steering column assembly disclosed by the subject invention provides a simple energy absorbing device capable of absorbing varying amounts of energy during an accident, e.g., by moving the moveable pin from the disengaged position to the engaged position, the steering column assembly increases the amount of energy absorbed as a result of axial movement of the column relative to the bracket. As such, the amount of energy absorbed by the steering column assembly may be altered as needed, even after installation into the vehicle.
Other advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:
Referring to the Figures, wherein like numerals indicate corresponding parts throughout the several views, a collapsible steering column assembly is generally shown at 20. The steering column assembly 20 is for a motor vehicle, and is collapsible along a longitudinal axis L during a collision event to reduce possible injuries to a driver of the vehicle as is well known in the art.
Referring to
The steering column assembly 20 further comprises an energy absorption device for absorbing energy imparted into the steering column assembly 20 during the collision event. Referring to
The slot 32 defined by the plate 28 is in spaced relationship relative to the column. The spaced relationship permits the plate 28 to deform inward towards the column jacket 24 or outward away from the column jacket 24, and guarantees that the deformation of the plate 28 is not interfered with by the column jacket 24. It is important that the plate 28 deform consistently so as to provide a predictable rate of energy absorption.
The slot 32 includes a first end 34 adjacent the opening 30, and extends to a second end 36 a pre-determined distance from the first end 34. Preferably, the pre-determined width W of the slot 32 is constant, i.e., does not change between the first end 34 and the second end 36. However, it should be understood that the slot 32 may taper near the second end 36 to increase the pre-determined width W of the slot 32. It should also be understood that the slot 32 may include a portion having a constant pre-determined width W and a tapering pre-determined width W. Accordingly, as shown in
A pin 46 is coupled to one of either the bracket 22 and the column jacket 24. The pin 46 is horizontally moveable relative to the plate 28 along the horizontal axis during the collision event. The pin 46 includes a diameter D greater than the pre-determined width W of the slot 32 yet less than the diameter D of the opening 30. The pin 46 is transversely moveable along a transverse axis T relative to the plate 28. The pin 46 is moveable between a disengaged position, withdrawn from the opening 30, and an engaged position, extending into the opening 30 and engaging the slot 32. In the engaged position, the pin 46 deforms the slot 32 in response to the horizontal movement of the plate 28 relative to the pin 46. It should be understood that the slot 32 may include a different geometry than specifically shown and described herein to accommodate differing design parameters and energy absorption requirements.
Preferably, the plate 28 is coupled to the column jacket 24 and the pin 46 is coupled to the bracket 22. Alternatively however, as is shown in
An actuator 48 is coupled to the pin 46 and interconnects the pin 46 and one of either the bracket 22 or the column jacket 24. The actuator 48 moves the pin 46 between the disengaged position and the engaged position in response to the collision event. Preferably, the actuator 48 includes a pyrotechnic device, but may alternatively include an electronic solenoid. It should be understood that the actuator 48 may include some other device capable of moving the pin 46 between the engaged position and the disengaged position in response to the collision event.
A post 50 is coupled to either one of the bracket 22 and the column jacket 24 and extends through the opening 30. The post 50 is interposed between the slot 32 and the pin 46 and includes a diameter D less than the diameter D of the pin 46 and greater than the pre-determined width W of the slot 32. The post 50 is horizontally moveable relative to the plate 28 along the horizontal axis during the collision event. Preferably, the post 50 is coupled to the bracket 22. It should be understood that when the post 50 is coupled to the bracket 22, the pin 46 is also coupled to the bracket 22. In the alternative, the post 50 may be coupled to the column jacket 24, with the pin 46 also being coupled to the column jacket 24.
A shown in
During a severe collision, the energy imparted to the steering column assembly 20 will be greater. To better protect the occupant, the energy absorbing device can be set to provide additional energy absorbing capabilities. When a collision is sensed to be severe, prior to impact of the column, actuator 48 is signaled to extend the pin 46 into the opening 30. Since the pin 46 includes a diameter D larger than the diameter D of the post 50, the pin 46 follows the post 50 through the slot 32, further deforming the edges 42 of the slot 32 beyond the deformation caused by the post 50. As in the interaction between the plate 28 and the post 50 described above, the amount of energy absorbed as a result of the deformation of the slot 32 by the pin 46 is dependant upon the material properties of the plate 28 and the pin 46, and the geometric properties of the slot 32 and the pin 46.
Accordingly, the energy absorption device may be calibrated to provide for two different stages of energy absorption. A first stage in which just the post 50 interacts with the plate 28 to absorb energy, and a second stage in which both the post 50 and the pin 46 interact with the plate 28 to absorb energy.
In a first alternative embodiment of the energy absorption device shown in
In the second embodiment of the energy absorption device shown in
In the third alternative embodiment of the energy absorption device shown in
Accordingly, the third embodiment of the energy absorption device provides three stages of energy absorption capabilities. In a first stage, the first pin 46 and the second pin 82 are in the disengaged position, therefore only the post 50 interacts with the plate 28 to provide the energy absorption capabilities. In a second stage, the first pin 80 is in the engaged position and the second pin 82 is in the disengaged position, therefore the post 50 and the first pin 80 interact with the plate 28 to provide the energy absorption capabilities. In a third stage, both the first pin 80 and the second pin 82 are in the engaged position, therefore the post 50 and both the first pin 80 and the second pin 82 interact with the plate 28 to provide the energy absorption capabilities.
In a fourth alternative embodiment of the energy absorption device shown in
The foregoing invention has been described in accordance with the relevant legal standards; thus, the description is exemplary rather than limiting in nature. Variations and modifications to the disclosed embodiments may become apparent to those skilled in the art and do come within the scope of the invention. Accordingly, the scope of legal protection afforded this invention can only be determined by studying the following claims.
