IMPACT ABSORBER

• US 3,814,470 A
• Filed: 08/16/1972
• Issued: 06/04/1974
• Est. Priority Date: 08/16/1972
• Status: Expired due to Term

• Current Assignee: Lawrence A. Nattrass, Thomas P. Kicher
• Original Assignee: Lawrence A. Nattrass, Thomas P. Kicher
• Inventors: Kicher, Thomas P., Nattrass, Lawrence A.
• Primary Examiner(s): Wood, Jr., M. Henson
• Assistant Examiner(s): Saifer, Robert
• Application Number:
  US05/281,177
• Time in Patent Office: 657 Days
• Field of Search: 293/70,89 267/139,140
• US Class Current: 293/136
• CPC Class Codes: B60R 19/26 comprising yieldable mounting means B60R19/38 takes precedence; springs, shock absorbers, or means for damping vibrations per se F16F

Abstract

A mechanical energy storage device is disclosed in which a column is elastically buckled to develop a constant force over an extended axial deflection of the column end. The constant deflection force produces a substantially square wave response allowing maximum energy storage in systems where limits are imposed on both deflection and force. Several embodiments disclose buckling mode control means for changing the buckling force into successively higher levels. The disclosed mode control means comprises restraining surfaces which restrict lateral deflection of column midportions and thereby cause the column to buckle into successively greater numbers of waves in response to increased end deflection.

Claims

1. An energy absorbing bumper system for a vehicle comprising a rigid frame, a bumper, an elastic column connected between the frame and the bumper, mounting means for holding one end of the column stationary with respect to the frame, guide means for limiting movement of the other end of the column along a substantially axial direction and allowing lateral movement of the midportion of the column during buckling action therein, buckling mode control jeans for changing the mode of buckling when deflection of said other end towards said one end reaches a predetermined point whereby the buckling force is increased from a first level to a second level to absorb a greater amount of energy per unit of travel.

2. A bumper system as set forth in claim 1 wherein said mounting means is adapted to prevent its associated column end from pivoting and restraining means is provided to prevent said other end from pivoting.

3. A bumper system as set forth in claim 2 wherein said mode control means comprises a surface which limits lateral movement of the column to a predetermined maximum.

4. A bumper system as set forth in claim 3 wherein said surface is spaced laterally on one side of the column, and including a second surface on the opposite side of the column having substantially the same spacing from the column as the spacing of the first mentioned surface from the column.

5. A bumper system as set forth in claim 3 wherein said column is formed of a material having a modulus of elastic resilience substantially in excess of 670 in-lb/in3.

6. A bumper system as set forth in claim 5 wherein said column material is fiber reinforced resin having its fibers aligned in a direction along the column axis.

7. An elastic energy absorbing system in a bumper assembly of a vehicle comprising a rigid vehicle frame, a bumper carried on the frame, an elastic column, means for holding one end of the column stationary with respect to the frame, means at the other end of the column causing the column to move in response to movement of the bumper, guide means for limiting movement of the other column end along a substantially axial direction, buckling control surface means including a surface laterally displaced from a midportion of the column and adapted to prevent lateral buckling of the column midportion substantially beyond the surface when the one end of the column is deflected in response to bumper movement whereby the column is caused to buckle into a secondary mode to increase its resiStance to bumper movement.

8. An elastic energy absorbing system as set forth in claim 7 including claming means at each end of the column for maintaining the column end portions in alignment with a plane defined by a free axis of the column.

9. An elastic energy absorbing system as set forth in claim 8 wherein a second column is provided in parallel relationship with said column whereby substantially equal resisting forces are developed by said columns when said bumper is deflected.

10. An elastic energy absorbing system as set forth in claim 9 wherein said columns are longitudinally contiguous.

11. A bumper assembly comprising a rigid vehicle frame generally defining a longitudinal vehicle axis, a rigid bumper at one end of the frame and extending generally transverse to the vehicle axis, a pair of spaced elastic columns arranged substantially parallel to the vehicle axis, means for fixing end portions of each column distant from the bumper relative to the frame and holding such distant portions in parallel alignment with the vehicle axis, means for fixing the other end portions of each column relative to said bumper and for holding such portions in parallel alignment with the vehicle axis, guide means for limiting movement of said other column ends along a direction substantially parallel to the vehicle axis, a restraining surface associated with each column supported on the vehicle frame and having a predetermined lateral spacing from a normal position of the associated column whereby lateral deflection of said columns is limited to thereby cause said columns to change from a first buckling mode to a higher order mode when bumper retraction movement exceeds a predetermined distance.

12. A bumper assembly as set forth in claim 11 wherein said columns are generally rectangular in section transverse to said vehicle axis and each of said restraining surfaces include flat portions lying in a plane parallel to the vehicle axis and parallel to one of the wide sides of the associated column.

13. A bumper assembly as set forth in claim 12 wherein said guide means includes said restraining surfaces whereby said restraining surfaces resist lateral forces on said other column ends.

14. A mechanical energy storage device adapted to provide at least two distinct substantially constant force levels over an extended deflection comprising an elastic column adapted to buckle when subjected to an axial end force, guide means for axially guiding one end of the column relative to the other, restraining means for preventing the ends of the column from pivoting out of an axial plane, and buckling control means for causing the column to buckle into a higher mode when end deflection of the column reaches a predetermined amplitude whereby the buckling force developed by the column increases to a corresponding higher level.

15. A mechanical energy storage device adapted to provide at least two distinct substantially constant force levels over an extended deflection comprising an elastic column adapted to buckle when subjected to an axial end force, guide means for axially guiding one end of the column relative to the other, and buckling control means for causing the column to buckle into a higher mode when end deflection of the column reaches a predetermined amplitude whereby the buckling force developed by the column increases to a corresponding higher level, said buckling control means including a first surface adjacent the midportion of the column and laterally spaced from a free position of the column.

16. A device as set forth in claim 15 wherein said buckling control means includes a second surface on a side of the column opposite said first surface, said second surface being laterally spaced from the free position of the column.

17. A device as set forth in claim 15 wherein said buckling control means includes a second surface on a side of the column opposite said first surface, said second surface being contiguous to said column at its free positIon.

18. A mechanical energy storage device adapted to provide at least two distinct substantially constant force levels over an extended deflection comprising an elastic column adapted to buckle when subjected to an axial end force and formed of a material having a modulus of elastic resilience substantially in excess of 670 in.-lb./in.3, guide means for axially guiding one end of the column relative to the other, and buckling control means for causing the column to buckle into a higher mode when end deflection of the column reaches a predetermined amplitude whereby the buckling force developed by the column increases to a corresponding higher level.