Land vehicles – Wheeled – Running gear
Reexamination Certificate
1999-02-25
2001-02-06
Dickson, Paul N. (Department: 3618)
Land vehicles
Wheeled
Running gear
C188S374000, C188S371000
Reexamination Certificate
active
06183012
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention concerns an energy absorbing device with a double winding for motor vehicle steering columns.
The device in accordance with the invention applies in particular to a steering column which can be adjusted in depth or in inclination or a steering column which can be adjusted in depth and in inclination, comprising a steering shaft mounted in a body-tube which is supported and immobilized in the required position, the body-tube being connected by a support assembly to the chassis or to a part of the body of the vehicle.
2. Description of the Prior Art
Ongoing safety improvements concerning steering columns oblige manufacturers to control all parameters of energy absorbing systems. The method of absorbing energy by unwinding a metal wire is increasingly used for steering columns and it is now necessary but difficult to vary the energy absorbing travel in accordance with a defined impact force.
The resulting compromise often leads steering column manufacturers to manufacture wires of complex shape or of varying section. The major disadvantage lies in the use of the product, which leads the manufacturer to costly technology solutions.
OBJECT OF THE INVENTION
The main object of this invention is to propose an energy absorbing device which uses a wire that is of simple shape and easy to make, which absorbs exactly a predetermined quantity of energy to be dissipated and which is easy to fit within the overall size of existing steering columns.
SUMMARY OF THE INVENTION
According to the invention, the energy absorbing device for a motor vehicle steering column comprising a steering shaft rotatably mounted in a body-tube connected by a support assembly to the chassis of the vehicle and is intended to operate in a direction substantially parallel to the axis of the steering column,
the support assembly comprising a mobile support mounted on the body-tube, a fixed support fastened to the chassis of the vehicle, the mobile support being immobilized on the fixed support with a particular force, and a double winding of a metal member of particular section comprising two coaxial windings joined by a central portion,
the double winding being mounted on a member rotating on a fixed shaft attached to the fixed support and the central portion of the double winding being mounted on the mobile support so that in the event of an impact the mobile support pushes on the central portion of the double winding to unwind the double winding and absorb the energy to be dissipated.
In a particularly simple embodiment of the invention, the double winding comprises two helical windings in opposite directions with the same number of turns in each winding. The winding are joined by a central loop that cooperates with the mobile support so that in the event of an impact the two windings are unwound simultaneously to absorb energy.
In a more developed embodiment of the invention, the double winding comprises two helical windings in opposite directions with different numbers of turns in each winding. The windings are joined by a central loop which cooperates with the mobile support member so that in the event of an impact initially both windings are unwound simultaneously and subsequently a single winding is unwound, which varies the absorption of energy over time.
In order to adapt at best the device of the invention, the metal member of the double winding has a round section, and in other embodiments, this section is square or rectangular or other.
A particularly interesting implementation of the energy absorbing device according to the invention has the following structure:
the fixed support comprises two substantially parallel lugs between which the mobile support is engaged, each of the lugs having a hole through which passes the fixed shaft of the rotary member of the energy absorbing device,
the mobile support has two side portions and a connecting portion, each of the side portions having a hole in its lower part through which passes the shaft of a system for adjusting the inclination and/or the depth of the steering column,
each of the side portions has an oblong hole in its upper part through which passes the fixed shaft of the rotary member of the energy absorbing device, the length of which corresponds to the energy recovery travel,
the turning member is on the fixed shaft of the energy absorbing device which is immobilized on each of the lugs of the fixed support member with a particular clamping force,
the central portion of the double winding is hooked over a lug in the connecting portion of the mobile support member, passing over the lug and engaging in notches on each side of the lug, so that in the event of an impact the steering wheel with the body-tube and the mobile support move towards the front of the vehicle, entraining the double winding, which unwinds around the fixed shaft attached to the fixed support.
The energy absorbing device in accordance with the invention therefore has the advantage of a structure that is very simple to manufacture, with guaranteed quality of manufacture in a mass production situation, as is the case in the automotive industry. What is more, the device fits easily within the overall size of existing steering columns. The double winding system increases the force absorbed whilst retaining the same unwinding travel. It also has the advantage of a small number of parts and of very easy fixing to its support, without requiring any additional parts or welds to hold it in place.
REFERENCES:
patent: 3126072 (1964-03-01), Johansson
patent: 4531619 (1985-07-01), Eckels
patent: 5961146 (1999-10-01), Matsumoto et al.
patent: 6019391 (2000-02-01), Stuedemann et al.
patent: 195 10 615 A1 (1996-09-01), None
Dufour Christophe
Fargeas Vincent
Millet Pascal
Dickson Paul N.
Fleming Faye M.
Laubscher & Laubscher
Lemforder Nacam SA
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