ENERGY ABSORBER FOR MOTOR VEHICLE STEERING COLUMN

Abstract: An actively variable energy absorber including a convex anvil (32) on a steering column housing, a flat metal strap (36) attached to a steering column support and slidably engaging the convex anvil (32) on an active surface area of the convex anvil (32), and a control apparatus for actively varying the geometric relationship between the flat metal strap (36) and the convex anvil (32) in response to changes in a control variable thereby to adjust the magnitude of the active surface area. Adjusting the magnitude of the active surface area changes the severity of plastic deformation of the flat metal strap (36) and the magnitude of the friction between the flat metal strap (36) and the convex anvil (32) thereby to adjust the force resisting linear translation of the steering column housing.

Description: ENERGY ABSORBER FOR MOTOR VEHICLE STEERING COLUMN TECHNICAL HELD This invention relates to an energy absorber for a motor vehicle steering column. BACKGROUND OF THE INVENTION A typical energy absorbing steering column on a motor vehicle includes a housing or mast jacket which translates linearly through a collapse stroke during a collision ofthe motor vehicle with another object when a steering hand wheel on the steering column is impacted by the operator ofthe motor vehicle. The mast jacket translates against a resisting force produced by an energy absorber which converts into work a fraction ofthe kinetic energy ofthe operator. Commonly, the resisting force is created by plastic deformation of a metal element ofthe energy absorber. For example, in the energy absorber described in United States Patent 3,392,599, steel spheres plastically deform a metal mast jacket by rolling tracks in the mast jacket. In other prior energy absorbers, a flat metal strap is plastically deformed by being pulled over a stationary anvil or vice versa. Optimal performance of such energy absorbers is achieved when the kinetic energy ofthe operator is completely converted into work at the completion ofthe maximum collapse stroke ofthe mast jacket. However, because these energy absorbers are not adjustable after the steering column is assembled but operators of differing weight often operate the motor vehicle, optimal energy absorbing performance may not always occur. United States Patent 4,886,295 describes an energy absorbing motor vehicle steering column having an energy absorber which is actively variable during Operation ofthe motor vehicle for more optimal energy absorbing performance and which includes a plurality of roll deformers in an annulus between an inner tube and a longitudinally split outer tube. An expandable bag having fluid therein is disposed around the split outer. A control system which monitors control variables characteristic ofthe kinetic energy of an operator ofthe motor vehicle controls the fluid pressure in the bag and, therefore, the interference fit ofthe roll deformers between the inner and outer tubes, to optimize the performance ofthe energy absorber. SUMMARY OF THE INVENTION This invention is a new and improved actively variable energy absorber including a convex anvil on one of a steering column housing and a steering column support, a flat metal strap attached to the other ofthe steering column housing and the steering column support and slidably engaging the convex anvil on an active surface area ofthe convex anvil, and a control apparatus for actively varying the geometric relationship between the flat metal strap and the convex anvil in response to changes in a control variable thereby to adjust the magnitude of the active surface area. Adjusting the magnitude of the active surface area changes the severity of plastic deformation ofthe flat metal strap and the magnitude ofthe friction between the flat metal strap and the convex anvil thereby to adjust the force resisting linear translation ofthe steering column housing and the corresponding performance ofthe energy absorber. In some embodiments ofthe actively variable energy absorber according to this invention, the flat metal strap is plastically deformed by being pulled over a single convex anvil during linear translation ofthe steering column housing. In other embodiments ofthe energy absorber according to this invention, the flat metal strap is plastically deformed by being pulled across a plurality of convex anvils or by being pulled edgewise between a pair convex anvils. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic elevational view of a motor vehicle steering column having thereon an actively variable energy absorber according to this invention; Figure 2 is a fragmentary perspective view ofthe actively variable energy absorber according to this invention; Figure 3 is a fragmentary perspective view of a modified embodiment of the actively variable energy absorber according to this invention; Figure 4 is a fragmentary perspective view of a second modified embodiment ofthe actively variable energy absorber according to this invention; Figure 5 is a fragmentary perspective view of a third modified embodiment ofthe actively variable energy absorber according to this invention; Figure 6 is fragmentary perspective view of a fourth modified embodiment ofthe actively variable energy absorber according to this invention; Figure 7 is a fragmentary perspective view of a portion ofthe fourth modified embodiment ofthe actively variable energy absorber according to this invention; Figure 8 is a schematic plan view of a fifth modified embodiment ofthe actively variable energy absorber according to this invention; Figure 9 is fragmentary, exploded perspective view of a sixth modified embodiment ofthe actively variable energy absorber according to this invention; and Figure 10 is fragmentary perspective view of a seventh modified embodiment ofthe actively variable energy absorber according to this invention. DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to Figure 1, a motor vehicle steering column 10 includes a housing 12, a steering shaft 14 supported on the housing for rotation about a longitudinal centerline 16 ofthe steering column, and a steering hand wheel 18 connected to an outboard end ofthe steering shaft and pivotable up and down for vertical adjustment relative to an operator, not shown, ofthe motor vehicle seated on a seat 20 behind the steering hand wheel in conventional fashion. A steering column support 21 includes a lower bracket 22 on a schematically represented body structure 24 ofthe motor vehicle and a plurality of vertical hanger bolts 26 which form a shelf on the vehicle body for a lateral rod 27 on the housing 12. In a collision ofthe motor vehicle with another object, the vehicle body decelerates more rapidly than the operator so that the operator is thrust against the steering hand wheel 18 with an impact represented by a schematic vector force "F". When the operator impacts the steering hand wheel, the corresponding force on the steering column housing 12 initiates linear translation ofthe steering column housing 12 relative to the steering column support 21 in a collapse stroke in the direction ofthe centerline 16 ofthe steering column. An actively variable energy absorber 28 according to this invention, represented schematically in Figure 1, between the steering column housing 12 and the steering column support 21 resists linear translation ofthe steering column housing to decelerate the occupant while at the same time converting into work a fraction ofthe occupant's kinetic energy. Referring to Figure 2, the actively variable energy absorber 28 includes a reaction member 30 rigidly attached to the steering column housing 12 having a cylindrical surface thereon defining a convex anvil 32 around a longitudinal centerline 34 ofthe reaction member perpendicular to the direction ofthe linear translation ofthe steering column housing during its collapse stroke. A J- shaped flat metal strap 36 ofthe energy absorber 28 has a first leg 38 on one side ofthe reaction member adapted for rigid attachment to the steering column support 21, an unattached or free second leg 40 on the other side ofthe reaction member, and a concave web 42 between the first and the second legs facing convex anvil 32. A control apparatus 43 ofthe energy absorber 28 includes a restraint pin 44 supported on the steering column housing 12 parallel to the convex anvil 32 for translation in an arc about the centerline 34 toward and away from the second leg 40 ofthe flat metal strap. A schematically represented actuator 46 on the steering column housing translates the restraint pin toward and away from the second leg ofthe metal strap. The actuator 46 is controlled by a schematically represented electronic control module ("ECM") 48, Figure 1. A transducer 50, Figure 1, ofthe control apparatus 43 on the seat 20 provides an electronic signal to the ECM 48 corresponding to the magnitude of a control variable, e.g. the weight ofthe operator ofthe motor vehicle, characteristic ofthe kinetic energy ofthe operator. Other transducers, not shown, may provide electronic signals to the ECM 48 corresponding to the magnitudes of other control variables, e.g. vehicle velocity. The force required to plastically deform the flat metal strap 36 by pulling it over the convex anvil 32 manifests itself as a force resisting linear translation ofthe steering column housing 12 in its collapse stroke. Friction between the flat metal strap 36 and the convex anvil 32 mamfests itself as an additional force resisting linear translation ofthe steering column housing in its collapse stroke. The magnitudes ofthe resisting forces attributable to metal deformation and to friction depend upon a number of variables including the yield strength ofthe material from which the flat metal strap 36 is made and its physical dimensions, the coefficient of friction between the flat metal strap and the convex anvil 32, the radius of curvature ofthe convex anvil, and the area of contact between the flat metal strap and the convex anvil referred to herein as the "active surface area" ofthe convex anvil. These variables are related according to the following equation: F = A - w -r (\ - b - μ) - R Where F = total force resisting linear translation ofthe steering column housing A = a material related constant, e.g. yield strength W = width ofthe flat metal strap t = thickness ofthe flat metal strap R = radius ofthe convex anvil b = parameter related to the active surface area ofthe convex anvil μ = contact friction coefficient In operation, at the onset of linear translation ofthe steering column housing 12 initiated by the impact F on the steering hand wheel 18. the concave web 42 of the metal strap is thrust against and the flat metal strap is pulled across the convex anvil 32 while the unrestrained second leg 40 fens outward until intercepted by the restraint pin 44 as illustrated in broken lines in Figure 2. As the second leg fans outward, the active surface area ofthe convex anvil decreases. The position ofthe restraint pin 44 within its range of positions thus establishes the magmtude or size ofthe active surface area ofthe convex anvil. As the active surface area increases and decreases, the severity of plastic deformation ofthe flat metal strap across the convex anvil and the magnitude of the friction between the flat metal strap and the convex anvil likewise increase and decrease. The position ofthe restraint pin 44 is established by the ECM 48 through the actuator 46 in accordance with the magnitude ofthe control variable, i.e. the weight ofthe operator on the seat 20, as communicated to the ECM by the transducer 50. As the control variable changes, e.g. as operators of successively greater weight occupy the seat 20, the actuator 46 progressively minimizes the separation between the restraint pin 44 and second leg 40 ofthe metal strap and increases the active surface area ofthe convex anvil by more completely wrapping the flat metal strap around the convex anvil during the collapse stroke ofthe steering column housing. The magnitude ofthe force resisting linear translation ofthe steering column housing in its collapse stroke, therefore, increases for more optimal energy absorbing performance. Referring to Figure 3, a modified actively variable energy absorber 28 A according to this invention includes a pair of reaction members 52A,52B each rigidly attached to the steering column housing 12. The reaction members have cylindrical surfaces thereon defining respective ones of a pair of convex anvils 54A,54B around corresponding ones of a pair of longitudinal centerlines 56A,56B perpendicular to the direction of linear translation ofthe steering column housing during its collapse stroke. An M-shaped flat metal strap 58 has a pair of legs 60A,60B outboard ofthe reaction members 52A,52B, a lateral web 62 facing an abutment 64 on the steering column support 21, and a pair of concave webs 66A,66B facing the convex anvils 54A,54B. A control apparatus 43A ofthe modified energy absorber 28A includes a pair of restraint pins 68A,68B supported on the steering column housing 12 outboard of the legs 60A,60B ofthe flat metal strap 58 for translation toward and away from the legs. A pair of schematically represented actuators 70A.70B on the steering column housing translate the restraint pins toward and away from the legs. The actuators 70A,70B are controlled by the ECM 48. The transducer 50 on the seat 20 provides an electronic signal to the ECM 48 corresponding to the magmtude ofthe aforesaid control variable characteristic ofthe kinetic energy ofthe operator. In operation, at the onset of linear translation ofthe steering column housing 12 initiated by the impact F on the steering hand wheel 18, the abutment 64 thrusts the concave webs 66A.66B ofthe flat metal strap 58 against and pulls the flat metal strap over the convex anvils 54A,54B while the legs 60A,60B ofthe metal strap fan outward until intercepted by the restraint pins 68A,68B. As the legs 60A,60B fen outward, the active surface area ofthe each ofthe convex anvils 54A,54B decreases. The positions ofthe restraint pins 68A,68B within their range of positions thus establishes the magmtude or size ofthe active surface area of each ofthe convex anvils. As the active surface areas increase and decrease, the severity of plastic deformation ofthe M-shaped flat metal strap across the convex anvils and the magnitude ofthe friction between the flat metal strap and the convex anvils likewise increase and decrease. The positions ofthe restraint pins 68A,68B are established by the ECM 48 through the actuators 70A,70B in accordance with the magnitude ofthe aforesaid control variable as communicated to the ECM by the transducer 50. As the control variable changes, e.g. as operators of successively greater weight occupy the seat 20, the actuators 70A,70B progressively minimize the separation between the restraint pins 68 .68B and legs 60A,60B ofthe flat metal strap thereby to increase the active surface areas ofthe convex anvils by more completely wrapping the flat metal strap around the convex anvils during the collapse stroke of the steering column housing. The magnitude of the force resisting linear translation ofthe steering column housing in its collapse stroke, therefore, increases for more optimal energy absorbing performance. Referring to Figure 4, a second modified actively variable energy absorber 28B according to this invention includes a reaction member 72 supported on the steering column housing 12 for linear translation in the direction of a longitudinal centerline 74 ofthe reaction member perpendicular to the direction ofthe linear translation ofthe steering column housing during its collapse stroke. The reaction member 72 includes a plurality of cylindrical surfaces defining respective ones of a plurality of three convex anvils 76A,76B,76C having progressively smaller radii of curvature around the centerline 74. A J- shaped flat metal strap 78 has a first leg 80 adapted for rigid attachment to the steering column support 21 on one side ofthe reaction member, an unattached or free second leg 82 on the other side ofthe reaction member, and a concave web 84 between the first and the second legs. A restraint pin 86 is rigidly attached to the steering column housing 12 outboard ofthe second leg 82 ofthe flat metal strap. A control apparatus 43B ofthe second modified energy absorber 28B includes a schematically represented actuator 88 on the steering column housing operable to linearly translate the reaction member 72 between a plurality of three positions in which respective ones ofthe three convex anvils 76A,76B,76C having greater or smaller radii of curvature face the concave web 84 ofthe flat metal strap 78. The actuator 88 is controlled by the ECM 48. The transducer 50 on the seat 20 provides an electronic signal to the ECM 48 corresponding to the magmtude ofthe aforesaid control variable characteristic ofthe kinetic energy of the operator. In operation, at the onset of linear translation ofthe steering column housing 12 initiated by the impact F on the steering hand wheel 18, the concave web 84 of the flat metal strap is thrust against and the flat metal strap is pulled across the one ofthe three convex anvils 76A,76B,76C directly facing the concave web while the unrestrained second leg 82 fens outward until intercepted by the restraint pin 86. As the radius of curvature ofthe one ofthe convex anvils 76A,76B,76C facing the concave web 84 increases and decreases, i.e. as the reaction member translates back and forth in the direction of its centerline 74, the active surface area ofthe convex anvil increases and decreases. As the active surface area increases and decreases, the severity of plastic deformation ofthe flat metal strap across the convex anvil and the magmtude ofthe friction between the flat metal strap and the convex anvil likewise increase and decrease. The position ofthe reaction member 72 is established by the ECM 48 through the actuator 88 in accordance with the magnitude ofthe aforesaid control variable as communicated to the ECM by the transducer 50. As the control variable changes, e.g. as operators of successively greater weight occupy the seat 20, the actuator 88 translates the reaction member 72 in a direction aligning with the concave web 84 respective ones of convex anvils 76A,76B,76C of increasing radii of curvature thereby to increase the active surface area ofthe convex anvil facing the concave web during the collapse stroke ofthe steering column housing. The magnitude ofthe force resisting linear translation ofthe steering column housing in its collapse stroke, therefore, increases for more optimal energy absorbing performance. Referring to Figure 5, a third modified actively variable energy absorber 28C according to this invention includes a reaction member 90 supported on the steering column housing 12 for pivotal movement about an axis 92 perpendicular to the direction of linear translation ofthe steering column housing during its collapse stroke. The reaction member 90 has a pair of longitudinally separated convex anvils 94A,94B thereon. An S-shaped flat metal strap 96 has a first leg 98 adapted for rigid attachment to the steering column support 21, an unattached or free second leg 100, and a pair of concave webs 102AJ02B between the first and the second legs facing respective ones of the convex anvils 94A,94B. A control apparatus 43C ofthe third modified energy absorber 28C includes a restraint pin 104 supported on the steering column housing 12 for linear translation in a plane perpendicular to the axis 92 toward and away from the reaction member 90. A schematically represented actuator 106 on the steering column housing translates the restraint pin 104 toward and away from the reaction member. The actuator 106 is controlled by the ECM 48. The transducer 50 on the seat 20 provides an electronic signal to the ECM 48 corresponding to the magnitude ofthe aforesaid control variable characteristic ofthe kinetic energy ofthe operator. The restraint pin 104 increasingly limits clockwise rotation ofthe reaction member 90 about the axis 92 as the actuator 106 translates the restraint pin toward the reaction member. In operation, at the onset of linear translation ofthe steering column housing 12 initiated by the impact F on the steering hand wheel 18, the concave webs 102AJ02B ofthe flat metal strap 96 are thrust against and the flat metal strap is pulled across the convex anvils 94A,94B while the reaction member 90 is induced to rotate clockwise about the axis 92 until intercepted by the restraint pin 104. As the reaction member rotates clockwise, the flat metal strap unwraps from the convex anvils and the active surface area ofthe each ofthe convex anvils 94A,94B decreases. The second leg 100 ofthe flat metal strap is prevented from fanning outward by a wall 108 on the steering column housing 12. The position ofthe restraint pin 104 within its range of positions thus establishes the magnitude or size ofthe active surface area of each ofthe convex anvils. As the active surface areas increase and decrease, the severity of plastic deformation ofthe flat metal strap 96 across the convex anvils 94A,94B and the magnitude ofthe friction between the flat metal strap and the convex anvils likewise increase and decrease. The position ofthe restraint pin 104 is established by the ECM 48 through the actuator 106 in accordance with the magmtude ofthe aforesaid control variable as communicated to the ECM by the transducer 50. As the control variable changes, e.g. as operators of successively greater weight occupy the seat 20, the actuator 106 translates the restraint pin 104 toward the reaction member 90 thereby to increase the active surface areas ofthe convex anvils by more completely wrapping the flat metal strap around the convex anvils during the collapse stroke ofthe steering column housing. The magnitude ofthe force resisting linear translation ofthe steering column housing in its collapse stroke, therefore, increases for more optimal energy absorbing performance. Referring to Figures 6-7, a fourth modified actively variable energy absorber 28D according to this invention includes a first reaction member 110 rigidly supported in a box 112 fixed to the steering column housing 12. The first reaction member has a cylindrical surface thereon defining a first convex anvil 114 around a centerline 116 perpendicular to the direction of linear translation ofthe steering column housing during its collapse stroke. A second reaction member 118 having a cylindrical surface thereon defining a second convex anvil 120 is supported in the box 112 parallel to the first reaction member 110 by a pivotable cage 121 for linear translation in a plane perpendicular to the centerline 116 toward and away from the first reaction member. An S-shaped flat metal strap 122 has a first leg 124 adapted for rigid attachment to the steering column support 21, an unattached or free second leg 126, and a pair of concave webs 128AJ28B between the first and the second legs facing respective ones ofthe convex anvils 114,120. A control apparatus 43D ofthe fourth modified energy absorber 28D includes a restraint pin 136 supported by a schematically represented actuator 138 on the steering column housing for linear translation toward and away from a tang 139 ofthe cage 121. The actuator 138 is controlled by the ECM 48. The transducer 50 on the seat 20 provides an electronic signal to the ECM 48 corresponding to the magnitude ofthe aforesaid control variable characteristic ofthe kinetic energy ofthe operator. The restraint pin 136 increasingly limits clockwise pivotal movement ofthe cage 121 as the actuator 138 translates the restraint pin toward the tang 139 on the cage. In operation, at the onset of linear translation ofthe steering column housing 12 initiated by the impact F on the steering hand wheel 18, the concave webs 128A,128B ofthe flat metal strap 122 are thrust against and the flat metal strap is pulled across the convex anvils 114,120 while the second reaction member 118 is concurrently pulled away from the first reaction member in a direction causing the cage 121 to pivot clockwise until intercepted by the restraint pin 136. As the cage pivots clockwise, the flat metal strap unwraps from the convex anvils and the active surface area ofthe each ofthe convex anvils 114,120 decreases. The second leg 126 ofthe flat metal strap is prevented from fanning outward by a side ofthe box 112. The position ofthe restraint pin 136 within its range of positions thus establishes the magnitude or size ofthe active surface area of each ofthe convex anvils. As the active surface areas increase and decrease, the severity of plastic deformation ofthe flat metal strap 122 across the convex anvils 114,120 and the magmtude ofthe friction between the flat metal strap and the convex anvils likewise increase and decrease. The position ofthe restraint pin 136 is established by the ECM 48 through the actuator 138 in accordance with the magmtude ofthe aforesaid control variable as communicated to the ECM by the transducer 50. As the control variable changes, e.g. as operators of successively greater weight occupy the seat 20, the actuator 138 translates the restraint pin 136 toward the tang 139 on the cage 121 thereby to increase the active surface areas ofthe convex anvils by more completely wrapping the flat metal strap around the convex anvils during the collapse stroke ofthe steering column housing. The magnitude ofthe force resisting linear translation ofthe steering column housing in its collapse stroke, therefore, increases for more optimal energy absorbing performance. Referring to Figure 8, a fifth modified actively variable energy absorber 28E according to this invention includes a pair of reaction members 140AJ40B rigidly supported in a box 142 on the steering column housing 12 perpendicular to the direction of linear translation ofthe steering column housing during its collapse stroke. The reaction members have cylindrical surfaces thereon defining respective ones of a pair of convex anvils 144AJ44B. A third reaction member 146 having a third convex anvil 148 thereon is supported on the box 142 between the reaction members 140A,140B in a slot 150 in the box for linear translation toward and away from the reaction members 140AJ40B. A flat metal strap 152 traverses the box and has a first leg 154 adapted for rigid attachment to the steering column support 21, an unattached or free second leg 156, and a plurality of three concave webs 158A,158B,158C facing respective ones ofthe first, second and third convex anvils 144AJ44BJ48. A control apparatus 43E ofthe fifth modified energy absorber 28E includes a schematically represented wedge block 160 supported on the box 142 for linear translation perpendicular to the direction of linear translation ofthe third reaction member 146. The wedge block 160 has a ramp 161 thereon which intersects the slot 150 and blocks linear translation ofthe third reaction member away from the first and second reaction members 140AJ40B. A schematically represented actuator 164 on the steering column housing translates the wedge block 160 perpendicular to the direction of linear translation ofthe third reaction member 146. The actuator 164 is controlled by the ECM 48. The transducer 50 on the seat 20 provides an electronic signal to the ECM 48 corresponding to the magnitude ofthe aforesaid control variable characteristic ofthe kinetic energy ofthe operator. The wedge block 160 increasingly limits linear translation ofthe third reaction member 146 away from the first and second reaction members 140AJ40B as the actuator 164 translates the wedge block leftward and the ramp 161 further under the third reaction member. In operation, at the onset of linear translation ofthe steering column housing 12 initiated by the impact F on the steering hand wheel 18, the third concave web 158C ofthe flat metal strap 152 is thrust against and the flat metal strap is pulled across the third convex anvil 148 causing the third reaction member 146 to translate linearly away from the first and second reaction members 140AJ40B until intercepted by the ramp 161 on the wedge block 160. At the same time, the first and second concave webs 158AJ58B are thrust against and the flat metal strap is pulled across the convex anvils 144A,144B. As the third reaction member translates linearly away from the first and second reaction members, the flat metal strap unwraps from the convex anvils 144A,144B,148 and the active surface area ofthe each ofthe convex anvils decreases. The second leg 156 ofthe flat metal strap is prevented from fanning outward by a slot in the box 142. The position ofthe wedge block 160 within its range of positions thus establishes the magnitude or size ofthe active surface area of each ofthe convex anvils. As the active surface areas increase and decrease, the severity of plastic deformation ofthe flat metal strap 152 across the convex anvils 144AJ44B, 148 and the magnitude ofthe friction between the flat metal strap and the convex anvils likewise increase and decrease. The position ofthe wedge block 160 is established by the ECM 48 through the actuator 164 in accordance with the magnitude ofthe aforesaid control variable as communicated to the ECM by the transducer 50. As the control variable changes, e.g. as operators of successively greater weight occupy the seat 20, the actuator 164 translates the wedge block leftward, Figure 8, thereby to increase the active surface areas ofthe convex anvils 144A,144B,148 by more completely wrapping the flat metal strap around the convex anvils during the collapse stroke ofthe steering column housing. The magnitude ofthe force resisting linear translation ofthe steering column housing in its collapse stroke, therefore, increases for more optimal energy absorbing performance. Referring to Figure 9, a sixth modified actively variable energy absorber 28F according to this invention includes a 2-piece box 168A,168B fixed to the steering column housing 12 having an arc-shaped guide surface 170 thereon. A first reaction member 172 is rigidly supported in the box perpendicular to the direction of linear translation ofthe steering column housing during its collapse stroke and includes a cylindrical surface defining a first convex anvil 174. A second reaction member 176 is supported in the box 168AJ68B for linear translation in a plane perpendicular to the first reaction member. An arched surface on the second reaction member 176 defines a second convex anvil 178 thereon parallel to the first convex anvil 174. A flat metal strap 180 has a first leg 182 adapted for rigid attachment to the steering column support 21, an unattached or free second leg 184, an arch 186 feeing the guide surface 170 on the box, and a pair of concave webs 188A,188B facing respective ones ofthe first and second convex anvils 174,178. A control apparatus 43F ofthe sixth modified energy absorber 28F includes a schematically represented actuator 192 on the steering column housing operable to translate the second reaction member 176 back and forth to increase and decrease the separation between the first and the second convex anvils 174,178. The actuator 192 is controlled by the ECM 48. The transducer 50 on the seat 20 provides an electronic signal to the ECM 48 corresponding to the magnitude of the aforesaid control variable characteristic ofthe kinetic energy ofthe operator. In operation, at the onset of linear translation ofthe steering column housmg 12 initiated by the impact F on the steering hand wheel 18, the first and the second concave webs 188AJ88B are thrust against and the flat metal strap is pulled across the first and second convex anvils 174,178 while the second reaction member 176 is held stationary by the actuator 192. The second leg 184 ofthe flat metal strap is prevented from fanning outward by a side ofthe box 168 A, 168B. When the actuator 192 translates the second reaction member 176 in a direction increasing the separation between the first and the second convex anvils 174,178, the flat metal strap unwraps from the convex anvils and the active surface area ofthe each ofthe convex anvils decreases. The position of the second reaction member 176 within its range of positions thus establishes the magnitude or size ofthe active surface area of each ofthe convex anvils. As the active surface areas increase and decrease, the severity of plastic deformation ofthe flat metal strap 180 across the convex anvils 174,178 and the magnitude ofthe friction between the flat metal strap and the convex anvils likewise increase and decrease. The position ofthe second reaction member 176 is established by the ECM 48 through the actuator 192 in accordance with the magnitude ofthe aforesaid control variable as communicated to the ECM by the transducer 50. As the control variable changes, e.g. as operators of successively greater weight occupy the seat 20, the actuator 192 translates the second reaction member 176 toward the first reaction member 172, thereby to increase the active surface areas ofthe convex anvils 174,178 by more completely wrapping the flat metal strap around the convex anvils during the collapse stroke ofthe steering column housing. The magnitude ofthe force resisting linear translation ofthe steering column housing in its collapse stroke, therefore, increases for more optimal energy absorbing performance. Referring to Figure 10, a seventh modified actively variable energy absorber 28G according to this invention includes a pair of reaction members 194A,194B supported on the steering column housing 12 for rotation about respective ones of a pair of parallel axes 195AJ95B perpendicular to the direction of linear translation ofthe steering column housing. Side edges ofthe reaction members define respective ones of a pair of convex anvils 196A,196B each of which has a radius of curvature from a corresponding one ofthe rotation axes 195 J95B which increases along the length ofthe convex anvil so that the convex anvils flare radially outward from the rotation axes. A flat metal strap 198 in a plane perpendicular to the rotation axes 195 A, 195B includes a tongue 200 between the convex anvils 196 J96B, a pair of split edges 202A,202B, and a pair of concave shoulders 203A,203B intersecting the split edges and facing respective ones ofthe convex anvils 196AJ96B. The concave shoulders correspond to the concave webs ofthe embodiments ofthe actively variable energy absorbers according to this invention described above. The tongue 200 is adapted for rigid attachment to the steering column support 21. A control apparatus 43 G ofthe seventh modified energy absorber 28G includes a pair of schematically represented actuators 206A,206B on the steering column housing operable to rotate corresponding ones ofthe first and second reaction members 194AJ94B to progressively decrease the span between the convex anvils 196AJ96B. The actuators 206A,206B are controlled by the ECM 48. The transducer 50 on the seat 20 provides an electronic signal to the ECM 48 corresponding to the magnitude ofthe aforesaid control variable characteristic ofthe kinetic energy ofthe operator. In operation, at the onset of linear translation ofthe steering column housing 12 initiated by the impact F on the steering hand wheel 18, the first and the second concave shoulders 203A,203B are thrust against and the flat metal strap is pulled between and across the first and second convex anvils 196AJ96B while the first and second reaction members 194AJ94B are held stationary by the actuators 206A,206B. When the actuators 206A,206B rotate the first and second reaction members in directions increasing the span between the first and second convex anvils, the active surface area ofthe each ofthe convex anvils decreases and vice versa. The angular positions ofthe first and second reaction members 194AJ94B within their range of angular positions thus establishes the magnitude or size ofthe active surface area of each ofthe convex anvils. As the active surface areas increase and decrease, the severity of plastic deformation of the flat metal strap 198 across the convex anvils 196A,196B and the magnitude ofthe friction between the flat metal strap and the convex anvils likewise increase and decrease. The angular position of each ofthe first and second reaction members 194AJ94B is established by the ECM 48 through the actuators 206A,206B in accordance with the magnitude ofthe aforesaid control variable as communicated to the ECM by the transducer 50. As the control variable changes, e.g. as operators of successively greater weight occupy the seat 20, the actuators 206A,206B to rotate the first and second reaction members 194AJ94B in directions decreasing the span between the convex anvils 196A,196B, thereby to increase the active surface areas ofthe convex anvils during the collapse stroke ofthe steering column housing. The magnitude of the force resisting linear translation ofthe steering column housing in its collapse stroke, therefore, increases for more optimal energy absorbing performance. In each ofthe embodiments ofthe actively variable energy absorber according to this invention described herein, the flat metal strap is described as being attached to the steering column support and the convex anvils and the control apparatuses are described as being supported on the steering column housing. It is, of course, within the scope of this invention to reverse the positions ofthe flat metal strap, the reaction members, and the control apparatuses relative to the steering column housing and the steering column support. Having thus described the invention, what is claimed is:

Claims: CLAIMS 1. An actively variable energy absorber comprising: a flat metal strap, a convex anvil, an attachment means operable to attach the flat metal strap to a first one of a housing of a steering column and a steering column support and the convex anvil to a second one ofthe steering column housing and the steering column support so that during a collapse stroke ofthe steering column housing relative to the steering column support the flat metal strap is thrust against and pulled across an active surface area ofthe convex anvil and the collapse stroke ofthe steering column housing is opposed by a resisting force attributable to plastic deformation ofthe flat metal strap at the active surface area ofthe convex anvil and to friction between the flat metal strap and the active surface area ofthe convex anvil, and a control means operable in response to changes in a predetermined control variable to vary the active surface area ofthe convex anvil thereby to vary the magnitude ofthe resisting force by changing the severity of plastic deformation ofthe flat metal strap and the friction between the flat metal strap and the convex anvil. 2. An actively variable energy absorber comprising: a reaction member supported on a first one of a steering column housing and a steering column support, a convex anvil on the reaction member, a J-shaped flat metal strap including a first leg on a first side ofthe reaction member and a second leg on a second side ofthe reaction member and a concave web therebetween facing the convex anvil, an attachment means operable to attach a second one ofthe steering column housing and the steering column support to the first leg ofthe J-shaped flat metal strap so that during a collapse stroke ofthe steering column housing relative to the steering column support the flat metal strap is thrust against and pulled across an active surface area ofthe convex anvil and the collapse stroke ofthe steering column housing is opposed by a resisting force attributable to plastic deformation ofthe flat metal strap at the active surface area ofthe convex anvil and to friction between the flat metal strap and the active surface area ofthe convex anvil, a restraint pin supported on the first one ofthe steering column housing and the steering column support on the opposite side ofthe second leg ofthe J-shaped flat metal strap from the convex anvil so that the second leg is thrust against the restraint pin during the collapse stroke ofthe steering column housing, and a control means operable in response to changes in a predetermined control variable to vary the active surface area ofthe convex anvil thereby to vary the magnitude ofthe resisting force by changing the severity of plastic deformation ofthe flat metal strap and the friction between the flat metal strap and the convex anvil. 3. The actively variable energy absorber recited in claim 2 wherein the control means comprises: an actuator means operable to vary the magnitude ofthe active surface area of the convex anvil in contact with the concave web ofthe J-shaped flat metal strap during the collapse stroke ofthe steering column housing by moving the restraint pin toward and away from the second leg ofthe J-shaped flat metal strap in response to changes in the predetermined control variable. 4. The actively variable energy absorber recited in claim 2 wherein the control means comprises: a plurality of convex anvils on the reaction member each having a different radius of curvature relative to a longitudinal centerline ofthe reaction member, and an actuator means operable in response to changes in the predetermined control variable to linearly translate the reaction member in the direction ofthe longitudinal centerline thereof to align respective ones ofthe plurality of convex anvils thereon with the concave web ofthe J-shaped flat metal strap thereby to vary the magmtude ofthe active surface area ofthe convex anvil in contact with the concave web ofthe J-shaped flat metal strap during the collapse stroke of the steering column housing. 5. An actively variable energy absorber comprising: a first reaction member and a second reaction member each supported on a first one of a steering column housing and a steering column support, a first convex anvil and a second convex anvil on respective ones ofthe first reaction member and the second reaction member, an M-shaped flat metal strap having a first leg outboard ofthe first reaction member and a second leg outboard ofthe second reaction member and a pair of concave webs therebetween facing respective ones ofthe first convex anvil and the second convex anvil, an abutment means on a second one ofthe steering column housing and the steering column support operable to engage the M-shaped flat metal strap on a lateral web thereof between first and the second reaction members so that during a collapse stroke ofthe steering column housing relative to the steering column support the M-shaped flat metal strap is thrust against and pulled across an active surface area of each of first and the second convex anvils and the collapse stroke ofthe steering column housing is opposed by a resisting force attributable to plastic deformation ofthe M-shaped flat metal strap at the active surface area of each ofthe first and the second convex anvils and to friction between the M-shaped flat metal strap and the active surface area of each ofthe first and the second convex anvils, a first restraint pin supported on the first one ofthe steering column housing and the steering column support on the opposite side ofthe first leg ofthe M-shaped flat metal strap from the first reaction member so that the first leg is thrust against the first restraint pin during the collapse stroke ofthe steering column housing, a second restraint pin supported on the first one ofthe steering column housing and the steering column support on the opposite side ofthe second leg ofthe M- shaped flat metal strap from the second reaction member so that the second leg is thrust against the second restraint pin during the collapse stroke ofthe steering column housing, and a control means operable in response to changes in a predetermined control variable to vary the active surface area ofthe each ofthe first and the second convex anvils thereby to vary the magnitude ofthe resisting force by changing the severity of plastic deformation ofthe M-shaped flat metal strap and the friction between the M-shaped flat metal strap and each ofthe first and the second convex anvils. 6. The actively variable energy absorber recited in claim 5 wherein the control means comprises: an actuator means operable to vary the magnitude ofthe active surface area of each of first and the second convex anvils in contact with corresponding ones of the first and the second the concave webs ofthe M-shaped flat metal strap during the collapse stroke ofthe steering column housing by moving the first restraint pin toward and away from the first leg ofthe M-shaped flat metal strap and the second restraint pin toward and away from the second leg ofthe M- shaped flat metal strap in response to changes in the predetermined control variable. 7. An actively variable energy absorber comprising: a reaction member supported on a first one of a steering column housing and a steering column support for rotation about a pivot axis, a first convex anvil on the reaction member having a radius of curvature about the pivot axis, a second convex anvil on the reaction member remote from the first convex anvil, an S-shaped flat metal strap having a first leg outboard ofthe first convex anvil and a second leg outboard ofthe second convex anvil and a pair of concave webs therebetween facing respective ones ofthe first convex anvil and the second convex anvil, a restraint pin supported on the first one ofthe steering column housing and the steering column support adjacent to the reaction member, an attachment means operable to attach a second one ofthe steering column housing and the steering column support to the first leg ofthe S-shaped flat metal strap so that during a collapse stroke ofthe steering column housing relative to the steering column support the reaction member is thrust against the restraint pin and the flat metal strap is thrust against and pulled across an active surface area of each ofthe first and the second convex anvils and the collapse stroke ofthe steering column housing is opposed by a resisting force attributable to plastic deformation ofthe flat metal strap at the active surface area of each ofthe first and the second convex anvils and to friction between the flat metal strap and the active surface area of each ofthe first and the second convex anvils, and a control means operable in response to changes in a predetermined control variable to vary the active surface area of each ofthe first and the second convex anvils thereby to vary the magnitude ofthe resisting force by changing the severity of plastic deformation ofthe flat metal strap and the friction between the flat metal strap and each ofthe first and the second convex anvils. 8. The actively variable energy absorber recited in claim 7 wherein the control means comprises: an actuator means operable to vary the magnitude ofthe active surface area of each ofthe first and the second convex anvils in contact with corresponding ones ofthe first and the second concave webs ofthe S-shaped flat metal strap during the collapse stroke ofthe steering column housing by moving the restraint pin toward and away from the reaction member in response to changes in the predetermined control variable. 9. An actively variable energy absorber comprising: a first reaction member supported on a first one of a steering column housing and a steering column support, a first convex anvil on the first reaction member symmetric about a centerline of the first reaction member, a second reaction member supported on the first one ofthe steering column housing and the steering column support parallel to the first reaction member and for linear translation toward and away from the first reaction member in a plane perpendicular to the centerline thereof, a second convex anvil on the second reaction member, a cage supported on the first one ofthe steering column housing and the steering column support for pivotal movement in a plane perpendicular to the centerline ofthe first reaction member having a slot around the second reaction member operable to limit linear translation ofthe second reaction member away from the first reaction member, an S-shaped flat metal strap having a first leg outboard ofthe second convex anvil and a second leg outboard ofthe first convex anvil and a pair of concave webs therebetween facing respective ones ofthe first convex anvil and the second convex anvil, a restraint pin on the first one ofthe steering column housing and the steering column support adjacent to the cage, an attachment means operable to attach a second one ofthe steering column housing and the steering column support to the first leg ofthe S-shaped flat metal strap so that during a collapse stroke ofthe steering column housing relative to the steering column support the second reaction member is thrust against the cage and the cage is thrust against the restraint pin and the S-shaped flat metal strap is thrust against and pulled across an active surface area of each ofthe first and the second convex anvils so that the collapse stroke ofthe steering column housing is opposed by a resisting force attributable to plastic deformation ofthe S-shaped flat metal strap at the active surface area of each of the first and the second convex anvils and to friction between the S-shaped flat metal strap and the active surface area of each ofthe first and the second convex anvils, and a control means operable in response to changes in a predetermined control variable to vary the active surface area of each ofthe first and the second convex anvils thereby to vary the magnitude ofthe resisting force by changing the severity of plastic deformation ofthe flat metal strap and the friction between the flat metal strap and each ofthe first and the second convex anvils. 10. The actively variable energy absorber recited in claim 9 wherein the control means comprises: an actuator means operable to vary the magnitude ofthe active surface area of each ofthe first and the second convex anvils in contact with corresponding ones ofthe first and the second concave webs ofthe S-shaped flat metal strap during the collapse stroke ofthe steering column housing by moving the restraint pin on the first one ofthe steering column housing and the steering column support toward and away from the cage in response to changes in the predetermined control variable. 11. An actively variable energy absorber comprising: a first reaction member supported on a first one of a steering column housing and a steering column support, a first convex anvil on the first reaction member, a second reaction member supported on the first one ofthe steering column housing and the steering column support, a second convex anvil on the second reaction member a third reaction member supported on the first one of a steering column housmg and the steering column support for linear translation between the first and the second reaction members, a third convex anvil on the third reaction member, a wedge block on the first one ofthe steering column housing and the steering column support adjacent to the third reaction member, a flat metal strap between the third convex anvil and each ofthe first and the second convex anvils having a first concave web facing the first convex anvil and a second concave web facing the second convex anvil and a third concave web facing the third convex anvil, an attachment means operable to attach a second one ofthe steering column housing and the steering column support to an end ofthe flat metal strap so that during a collapse stroke ofthe steering column housing relative to the steering column support the third reaction member is thrust against the wedge block and the flat metal strap is thrust against and pulled across an active surface area of each ofthe first and the second and the third convex anvils and the collapse stroke ofthe steering column housing is opposed by a resisting force attributable to plastic deformation ofthe flat metal strap at the active surface area of each ofthe first and the second and the third convex anvils and to friction between the flat metal strap and the active surface area of each ofthe first and the second and the third convex anvils, and a control means operable in response to changes in a predetermined control variable to vary the active surface area of each ofthe first and the second and the third convex anvils thereby to vary the magnitude ofthe resisting force by changing the severity of plastic deformation ofthe flat metal strap and the friction between the flat metal strap and each ofthe first and the second and the third convex anvils. 12. The actively variable energy absorber recited in claim 11 wherein the control means comprises: a ramp on the wedge block feeing the third reaction member operable to limit linear translation ofthe third reaction member, and an actuator means operable to vary the magnitude ofthe active surface area of each ofthe first and the second and the third convex anvils in contact with corresponding ones ofthe first and the second the third concave webs ofthe flat metal strap during the collapse stroke ofthe steering column housing by linearly translating the wedge block to vary the separation between the ramp thereon and the third reaction member in response to changes in the predetermined control variable. 13. An actively variable energy absorber comprising: a first reaction member supported on a first one of a steering column housing and a steering column support, a first convex anvil on the first reaction member, a second reaction member supported on the first one ofthe steering column housing and the steering column support for linear translation toward and away from the first reaction member, a second convex anvil on the second reaction member, an arch-shaped guide surface on the first one ofthe steering column housing and the steering column support, a flat metal strap bearing against the arch-shaped guide surface and extending between the first and the second convex anvils having first concave web feeing the first convex anvil and a second concave web facing the second convex anvil, an attachment means operable to attach a second one ofthe steering column housing and the steering column support to an end ofthe flat metal strap so that during a collapse stroke ofthe steering column housing relative to the steering column support the flat metal strap is thrust against and pulled across an active surfece area of each ofthe first and the second convex anvils and the collapse stroke ofthe steering column housing is opposed by a resisting force attributable to plastic deformation ofthe flat metal strap at the active surface area of each ofthe first and the second convex anvils and to friction between the flat metal strap and the active surface area of each ofthe first and the second convex anvils, and a control means operable in response to changes in a predetermined control variable to vary the active surface area of each ofthe first and the second convex anvils thereby to vary the magmtude ofthe resisting force by changing the severity of plastic deformation ofthe flat metal strap and the friction between the flat metal strap and each ofthe first and the second convex anvils. 14. The actively variable energy absorber recited in claim 13 wherein the control means comprises: an actuator means operable to vary the magmtude ofthe active surface area of each ofthe first and the second convex anvils in contact with corresponding ones ofthe first and the second concave webs ofthe flat metal strap during the collapse stroke ofthe steering column housing by linearly translating the second reaction member toward and away from the first reaction member in response to changes in the predetermined control variable. 15. An actively variable energy absorber comprising: a first reaction member supported on a first one of a steering column housing and a steering column support for rotation about a first rotation axis, a first convex anvil on the first reaction member having a variable radius of curvature about the first rotation axis, a second reaction member supported on the first one ofthe steering column housing and the steering column support for rotation about a second rotation axis parallel to the first rotation axis, a second convex anvil on the second reaction member having a variable radius of curvature about the second rotation axis so that rotation of each ofthe first and the second reaction members about corresponding ones ofthe first and the second rotation axes varies the lateral separation between the first and the second convex anvils, a flat metal strap between the first and the second reaction members in a plane perpendicular to each ofthe first and the second rotation axes having first concave web facing the first convex anvil and a second concave web facing the second convex anvil, an attachment means operable to attach a second one ofthe steering column housing and the steering column support to an end ofthe flat metal strap so that during a collapse stroke ofthe steering column housing relative to the steering column support each ofthe first and the second concave webs ofthe flat metal strap is thrust against and the flat metal strap is pulled across an active surface area of a corresponding one ofthe first and the second convex anvils and the collapse stroke ofthe steering column housing is opposed by a resisting force attributable to plastic deformation ofthe flat metal strap at the active surfece area of each ofthe first and the second convex anvils and to friction between the flat metal strap and the active surfece area of each ofthe first and the second convex anvils, and a control means operable in response to changes in a predetermined control variable to vary the active surface area of each ofthe first and the second convex anvils thereby to vary the magnitude ofthe resisting force by changing the severity of plastic deformation ofthe flat metal strap and the friction between the flat metal strap and each ofthe first and the second convex anvils. 16. The actively variable energy absorber recited in claim 15 wherein the control means comprises: a first rotary actuator operable to rotate the first reaction member about the first rotation axis, and a second rotary actuator operable to rotate the second reaction member about the second rotation axis.

Inventors: BYERS DAVID MICHAEL, LI XIAOYU, ROE KEVIN LAWRENCE, BYERS, DAVID, MICHAEL, LI, XIAOYU, ROE, KEVIN, LAWRENCE
Applicants: DELPHI TECH INC, DELPHI TECHNOLOGIES, INC.
Application year: 2000
Main classification: B62D1
IPC codes: B62D1, F16F7