Land vehicles – Wheeled – Running gear
Reexamination Certificate
2002-06-07
2004-05-04
Jordan, Charles T. (Department: 3644)
Land vehicles
Wheeled
Running gear
C074S492000
Reexamination Certificate
active
06729648
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to energy absorbing devices, and more particularly, to energy absorbing subassemblies for use in mechanical systems for controlled energy absoprtion.
BACKGROUND OF THE INVENTION
The speed and power of motor vehicles has led to the development of numerous occupant protection systems designed to absorb or divert the energy of collisions. In frontal impact vehicle collisions, the driver is thrown forward due to inertia, striking the head, neck and chest against the steering wheel and inducing massive trauma. Many approaches have been taken to designing collapsible or otherwise energy absorbing steering wheels and column assemblies to reduce this type of injury. Most mechanical designs, apart from the well-developed air bag technology, utilize an inner shaft and an outer supporting post assembly in a telescoped arrangement, with energy absorbing elements mechanically interposed between or otherwise connected to the inner and outer elements. A deficiency of most prior art designs is a force displacement curve with excessive slope and high initial peak load forces in the region of initial movement of the column system.
For example, U.S. Pat. No. 3,457,800 discloses a steering column assembly comprising an upper and lower steering column shaft engaged to each other. A jacket tube rotatably supporting the upper steering column shaft, is supported by a clamp member which allows it to slide in the lower direction. A plastically deformable impact absorbing means, will absorb the impact, while the lower steering column shaft, including the flexible member will not transmit any harmful effect to the steering wheel.
U.S. Pat. No. 3,597,994 discloses a tubular steering column having telescopic portions arranged coaxially arranged about the steering shaft and an energy-absorbing member capable of plastic deformation under tension or compression.
U.S. Pat. No. 3,665,777 discloses a steering column assembly which includes an energy absorbing outer jacket and a telescopically collapsible steering shaft. The shaft has a resilient friction member separating the inner and outer shaft components. The friction member is radially compressed between the two components to maintain the relative position of the shaft components and prevent vibration.
U.S. Pat. No. 5,507,203 discloses a steering shaft coupling which contains an outer tubular shaft and an inner shaft slidably inserted within the outer tubular shaft. Additionally a biasing member positioned between the inner and outer shafts, produces a force which opposes the transmitted torque.
U.S. Pat. No. 6,109,652 discloses a steering column with upper and lower columns and a shock absorbing device therebetween. The shock absorbing device has a plurality of friction members, which contact the external surface of the lower column. The shock absorbing device effectively absorbs and relieves shock in the initial stage of a collision, protecting the driver.
U.S. Pat. No. 6,170,862 discloses a collapsible steering column that has an elongated hollow cylinder slidably mounted on a piston. The space between the interior wall of the cylinder and the piston is sealed in a gas-tight fashion. A coil spring inside the cylinder urges the piston and the bottom of the cylinder apart. When a collision occurs, the sensor sends an electronic signal which ignites the explosive compound and fractures the seal permitting the gas to escape, causing collapse of the cylinder.
U.S. Pat. No. 6,339,970 discloses a steering column which is telescopic in the event of a crash. The outer column tube is connected to a stem by means of a shearing body. The shearing body has a shearing area which is reduced relative to its external dimensions and determined by a projection connecting its two sections. This allows the shearing body to absorb relatively large axial forces and still permit maximum admissible shearing forces.
These prior art designs all have an outer tube that is deformable upon impact to thereby absorb energy. However, the energy absorption is not smooth, but occurs abruptly in early stages as various segments of the outer tube begin to plastically deformed.
U.S. Pat. No. 3,699,824 discloses an energy absorbing steering column having a pair of telescopic steering shaft sections and a pair of telescopic tubular sections that form an outer housing. The tubular sections are separated by a plurality of pre-stressed elastomeric members that are compressed when the column is collapsed thereby absorbing energy.
U.S. Pat. No. 3,757,601 discloses a tube assembly which includes a first tube section and a second tube section telescopically disposed relative to the first tube section. A plurality of spring pins are disposed between the tube sections to generate mechanical friction to effect energy absorption at a predetermined rate during forced telescopic collapse of the tube assembly.
U.S. Pat. No. 5,669,633 discloses two tubular members which are axially displaceable. One of the tubular members contains tear-off strips with bent-over front ends having bent-over sections engaging the other tubular member. Consequently, once a relatively large force is applied to the steering shaft along the flutes, the strips are torn off and deformed, causing displacement of the members relative to each other.
These prior art designs employ a lower column interferentially fitted into the upper column to form a shock absorbing device in the interferential fitting junction between the columns. The shock absorbing device includes anything from a plurality of pre-stressed elastomeric members or tear-off strips, to a plurality of spring pins which are disposed between the tube sections to generate friction. In the event of a collision, the lower column frictionally retracts into the upper column, absorbing energy and relieving the collision impact. However, at peak force, a relative displacement between the two columns can occur, thus, preventing the lower column from gradually retracting into the upper column, and transmitting excessive axial force to the steering wheel.
U.S. Pat. No. 3,392,599 discloses a collapsible steering column assembly which includes a pair of telescopically related cylinders with a plurality of hard spheroids engaged between the cylinders. Thus, once impact energy is applied to the steering column, the spheroids cause highly localized deformation in the contact surfaces of the cylinders.
U.S. Pat. No. 3,538,783 discloses two telescoping tubular members with a sleeve containing press-fitted balls. The sleeve and ball unit is placed to be engaged between the members creating substantial interference so as to roll and cause localized deformation of the members under telescopic movement.
U.S. Pat. No. 5,495,777 discloses a steering column which includes a tubular lower mast jacket, a tubular upper mast jacket telescoped inside the lower mast jacket, and a plurality of steel spheres fitted in an overlap between the mast jackets. A plastic ball sleeve contains pockets which loosely receive the steel spheres and prevent the spheres to roll freely. Thus, a significant amount of force is required to exceed the pockets and cause collateral damage to the steering column.
These prior art designs utilize spherical elements or rigid balls press-fitted in and between two telescopically engaged posts so that under impact the posts exhibit axial relative movement and the rigid balls cause localized plastic deformation of the wall surfaces of the posts along their spherical paths. However, one disadvantage of this design is that a high magnitude of initial load is needed to start the telescopic contraction of the posts. To better control by design this high magnitude of initial load, the shock absorbing characteristics of the apparatus have to be lowered so that furthered loads absorbed by the apparatus will be abruptly decreased. Thus, the impact absorption gradient is not optimal.
Finally, U.S. Pat. No. 4,006,647 utilizes spherical elements press-fitted between two telescopically engaged cylindrical members. The spherical elements are g
Hayes Bret
Jordan Charles T.
Roetzel & Andress
Sealy Technology LLC
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