Patent Description:
The invention can be applied in heavy-duty vehicles, such as trucks, buses and construction equipment, or in other vehicles, such as a car.

Conventional vehicles are fitted with a steering wheel to control the orientation of the wheels via a steering column. Such a steering wheel is made up of a steering wheel ring, a hub and one or more radial spokes that connect the steering wheel ring to the hub. The steering wheel hub causes a steering shaft to rotate. Other accessories, such as an air bag or a horn pad, may also be contained in, or disposed on, the steering wheel hub.

Vehicles generally have a steering wheel adjusting mechanism with which a driver may adjust the steering wheel in a position that is suitable for the present driver by partly displacing the steering wheel and/or the steering column forwards and backwards relative to the direction of travel of the vehicle and partly, simultaneously or as an option, tilt the steering wheel and that to the steering wheel attached steering column in order to change the angular position of the steering wheel and the steering column relative to the vehicle. The steering wheel adjusting mechanism is lockable in such a way that the steering wheel and that to the steering wheel attached steering column after adjustment may be locked in a desired position relative to the vehicle at the same time as the steering wheel and that to the steering wheel attached steering column still may be turned around the axis of the steering column thereby enabling steering of the vehicle.

One example of a steering wheel adjusting mechanism for motor vehicles, for example as disclosed in <CIT>, comprises a supporting arm pivotally attached to a part fixed on the vehicle, and a pivotally to the supporting arm attached steering shaft housing unit. The supporting arm is further attached over a first locking plate package to the steering shaft housing unit and over a second locking plate package to the fixed part of the vehicle in order, with these locking plate packages, to lock the steering shaft housing unit relative to the vehicle. The locking effect results from the friction between friction plates in each locking plate package.

A problem with such a steering wheel adjusting mechanism is that it cannot prevent a displacement of the steering column during a collision. In particular, in conventional heavy vehicles, such as trucks, the steering column tends to rotate toward the windshield under the effect of the system mass inertia during a frontal collision. This leads to an upward displacement of the steering wheel during a collision, which may lead to a dangerous position of the steering wheel relative to the driver. Indeed, if the driver is thrown forwards, it is highly probable that he will bump against the steering wheel with his chest, neck or face, which increases the risk of serious personal injury for the driver. This risk is not lowered by the airbag, because the airbag in the steering wheel develops essentially upwards instead of in the direction towards the driver during a collision, and does not give the driver the intended and necessary protection.

An object of the invention is to provide a steering column assembly, especially for trucks, that maintains the steering wheel at its optimal orientation relative to the driver during a collision, thus lowering the risk of serious injury for the driver.

The object is achieved by a steering column assembly according to claim <NUM>.

Thus, the locking means of the steering column assembly permits to keep the angular position of the steering wheel relative to the vehicle body during the short time period that follows a collision event and before the driver impacts the steering wheel. Furthermore, once the driver is impacting the steering wheel, the collapsible means permit to at least partially absorb the kinetic energy transmitted by the driver, thus reducing the reaction force transmitted by the steering column, and permit to maintain the steering wheel in an optimal orientation for the driver during the collision event.

<FIG> respectively show perspective and side views of an embodiment of a steering column assembly <NUM> for a motor vehicle. The steering column assembly <NUM> comprises a steering wheel <NUM> integral in rotation with a steering wheel housing unit <NUM>, said steering wheel housing unit <NUM> including a bearing device <NUM> in which is pivotally mounted a steering shaft <NUM> that is attached to the steering wheel <NUM>. The steering shaft <NUM> is mounted in a steering shaft housing unit <NUM> that is pivotally connected to a supporting bracket <NUM> about a first axis X1. This supporting bracket <NUM> is pivotally connected to a vehicle body <NUM> about a second axis X2.

The angular position of the steering shaft housing unit <NUM> relative to the supporting bracket <NUM> may advantageously be adjusted by first adjusting means and the angular position of the supporting bracket <NUM> relative to the vehicle body <NUM> may advantageously be adjusted by second adjusting means, so that the driver can adjust the position of steering wheel to his own needs. Third adjusting means may also be provided to adjust the orientation of the steering wheel <NUM> relative to the steering shaft housing <NUM>.

The first, second and third adjusting means may advantageously comprise electric motors adapted to move the steering shaft housing unit <NUM>, the supporting bracket <NUM> and the steering wheel <NUM> respectively.

As shown in <FIG>, the steering column assembly <NUM> further comprises first locking means <NUM> and second locking means <NUM> that are adapted to lock the steering shaft housing unit <NUM> and support <NUM> in a locked position during a collision event.

The second locking means <NUM> are conventional and consist in lamellar package that holds the steering shaft housing unit <NUM> and support <NUM> at a desired position during normal use with the aid of friction. A specific embodiment of such lamellar package is illustrated in <FIG>. In this embodiment, the second locking means <NUM> comprise a first set of thin friction plates <NUM> joined to the steering shaft housing unit <NUM> and a second set of thin friction plates <NUM> joined to the vehicle body <NUM>, each friction plate <NUM> of second set being disposed between two adjacent friction plates <NUM> of the first set. The first and second sets of friction plates <NUM>, <NUM> are slidably mounted along a support bar <NUM> that extends between a first T-shape end <NUM> and a second end <NUM>, a nut <NUM> being threadedly connected to the support bar <NUM> near the second end <NUM>. The first end <NUM> define a first abutment for the friction plates <NUM>, <NUM> and the nut <NUM> define a second abutment for the friction plates <NUM>, <NUM>. A piston <NUM> is slidably mounted along the support bar <NUM>, so that it can apply a compression force Fc on the friction plates <NUM>, <NUM> when it moves toward the first and second ends <NUM> and <NUM> of the support bar <NUM>, the friction plates <NUM>, <NUM> being compressed between the piston <NUM> and the first abutment or the second abutment. The compression force Fc applied by the piston <NUM> is controlled by a cylinder <NUM> that is adapted to induce a pivoting movement to a fork element <NUM> via a cylinder rod <NUM>, which pushes against a fork end <NUM> of the fork element <NUM>, the other end <NUM> thereof being integral in translation with the piston <NUM>. A sliding movement of the piston <NUM> may thus be induced by the cylinder <NUM>.

As shown in <FIG>, the first locking means <NUM> comprise a locking arm <NUM> extending between an upper end <NUM> pivotally connected to the steering shaft housing unit <NUM> and a lower end <NUM> pivotally connected to a collapsible element <NUM> that is fixedly connected to the supporting bracket <NUM>. The distance between the upper end <NUM> and the lower end <NUM> may advantageously be adjusted so that the length L0 of the locking arm <NUM> (see <FIG>) can be adjusted depending on the angle α1 of the steering shaft housing unit <NUM> relative to the horizontal in the normal position of use. In the embodiment shown, this adjustment is possible by using a telescopic locking arm <NUM>. The locking arm <NUM> thus comprises a first section <NUM> and a second section <NUM>, the first section <NUM> being telescopically received inside the second section <NUM>. The first section <NUM> has a toothed profile <NUM> along its outer periphery, said toothed profile <NUM> being adapted to interact with a locking pin <NUM> to lock the locking arm <NUM> in the position of use shown in <FIG>. The locking pin <NUM> is provided with a bevelled end <NUM> and is pivotally movable about a pivot shaft <NUM> between two positions, respectively an engagement position, in which the locking pin <NUM> engages the toothed profile <NUM> of the locking arm <NUM>, the bevelled end <NUM> being positioned between two contiguous teeth of said toothed profile <NUM>, thus preventing any relative displacement between the first and second sections <NUM> and <NUM>, and a disengagement position, in which the locking pin <NUM> is disengaged from the toothed profile <NUM>, the bevelled end <NUM> being slightly away from the teeth of the toothed profile <NUM>, thus allowing a relative displacement between the first and second sections <NUM> and <NUM>. This disengagement position thus allows an adjustment of the length L0 of the locking arm <NUM>. The second section <NUM> is advantageously provided with an aperture <NUM> facing the toothed profile <NUM> of the first section <NUM>, said aperture <NUM> being configured to allow the bevelled end <NUM> to pass through the second section <NUM> when the locking pin <NUM> moves from its release position to its locking position and vice versa.

The movement of the locking pin <NUM> from its engagement position to its disengagement position is actuated by a release rod <NUM> that is slidably connected to the locking pin <NUM>. The release rod <NUM> comprises one lower end section <NUM> that is slidably received in a slot <NUM> of the locking pin <NUM> and one upper end section <NUM> that is pivotally connected to cylinder rod <NUM> of a cylinder <NUM> (see <FIG>). When the cylinder <NUM> moves the cylinder rod <NUM> along a longitudinal direction, it induces an upward movement of the upper end section <NUM> and of the lower end section <NUM>. During its upward movement, the lower end section <NUM> follows a cam profile defined by the slot <NUM> and causes the locking pin <NUM> to pivot about the pivot shaft <NUM> from its engagement position to its disengagement position. The locking pin <NUM> is advantageously biased from its disengagement position to its engagement position under the action of a return spring <NUM>.

In the exemplary embodiment shown in <FIG>, the collapsible element <NUM> may comprise a bottom plate <NUM> that is fixedly connected to the supporting bracket <NUM>, the bottom plate <NUM> extending between a first end <NUM> and a second end <NUM>. A U-shape central section <NUM> of the bottom plate <NUM> pivotally supports the locking arm <NUM> at its free end <NUM>. The central section <NUM> is deformable under the force applied by the locking arm <NUM> so that its free end <NUM> is movable relative to the bottom plate <NUM> between an initial position (corresponding to the non-deformed state of the collapsible element <NUM>), in which it is close to the second end <NUM> of the bottom plate <NUM>, and a final position (corresponding to the totally deformed state of the collapsible element <NUM>), in which it is close to the first end <NUM> of the bottom plate <NUM>. As explained in the following paragraphs, the deformation of the central section <NUM> may not occur as long as the force applied by the locking arm <NUM> is less than a threshold value.

As illustrated in <FIG>, the steering column assembly <NUM> of the present invention may also comprise third locking means <NUM> to lock the steering wheel housing unit <NUM> in a specific angular position relative the steering shaft housing unit <NUM>. Such third locking means <NUM> are for example illustrated in <FIG>. They comprise a locking lever <NUM> having a tooth profile <NUM> along its upper side, the locking lever being pivotally connected to the steering shaft housing unit <NUM> about a pivot shaft <NUM>. A free end <NUM> of the locking lever <NUM>, which is integral in translation with the cylinder rod <NUM>, is movable under the action of the cylinder <NUM> between a locked position, illustrated in <FIG>, and a release position, illustrated in <FIG>. In the locked position, the teeth of the toothed profile <NUM> of the locking lever <NUM> are engaged with corresponding teeth <NUM> of a gear <NUM> fixedly connected to the steering wheel housing unit <NUM>, thus preventing any angular displacement between the steering wheel housing unit 1and the steering shaft housing unit <NUM>. In the release position, the free end <NUM> of the locking lever <NUM> is closer to the cylinder <NUM> than in the locked position, the teeth of the toothed profile <NUM> of the locking lever <NUM> thus being disengaged from the teeth <NUM> of the gear <NUM>, thus allowing an angular displacement between the steering wheel housing unit <NUM> and the steering shaft housing unit <NUM>.

The successive positions taken by the steering wheel assembly <NUM> during a collision event are illustrated in <FIG>.

In <FIG>, the steering wheel assembly <NUM> is in its normal position of use, before the collision event occurs. The angle of the steering shaft housing unit <NUM> relative to the horizontal H is equal to an initial value α1.

In <FIG>, the steering wheel assembly <NUM> is shown just after the collision event occurs and before the driver impacts the steering wheel. The collision event corresponding to a frontal collision, a force FEXT1 exercised by the inertia is thus applied in the forward vehicle direction. This force FEXT1 transmits a kinetic energy E1 to the steering shaft housing unit <NUM>. The angular position of steering wheel assembly <NUM> relative to the supporting bracket <NUM> being locked by the locking arm <NUM>, this kinetic energy E1 leads to a rotation of the supporting bracket <NUM> about the second shaft X2. The angle of the steering shaft housing unit <NUM> relative to the horizontal H thus slightly increases to a value α2. Until the kinetic energy E1 transmitted to the steering shaft housing unit <NUM> is below a threshold value Et, the collapsible element <NUM> stays in its non-deformed state.

In <FIG>, the steering wheel assembly <NUM> is shown after the collision event occurs and after the driver impacts the steering wheel. The driver thus exercises a force FEXT2 in the forward vehicle direction. This force FEXT2 transmits a kinetic energy E2 to the steering shaft housing unit <NUM>. This kinetic energy E2 being greater than the threshold value Et, this leads to a deformation of the collapsible element <NUM> that reaches its totally deformed state, and to both a rotation of the supporting bracket <NUM> about the second shaft X2 and a rotation of the steering shaft housing unit <NUM> about the first shaft X1. The combination of these two rotational movements results in a downward translation of the whole system. The angle of the steering shaft housing unit <NUM> relative to the horizontal H thus slightly decreases to a value α3, which is close to the initial value α1.

Claim 1:
A steering column assembly (<NUM>) for motor vehicles, comprising:
- a steering wheel (<NUM>),
- a steering shaft housing unit (<NUM>) including a steering shaft (<NUM>) that is joined to the steering wheel (<NUM>),
wherein the steering shaft housing unit (<NUM>) is pivotally connected to a supporting bracket (<NUM>) about a first shaft (X1), said supporting bracket (<NUM>) being pivotally connected to a vehicle body (<NUM>) about a second shaft (X2),
- first and/or second adjusting means adapted to adjust the angular position of the steering shaft housing unit (<NUM>) relative to the supporting bracket (<NUM>) and the angular position of the supporting bracket (<NUM>) relative to the vehicle body (<NUM>),
the steering column assembly (<NUM>) further comprising first locking means (<NUM>) adapted to lock the steering shaft housing unit (<NUM>) in a locked position until a kinetic energy transmitted to the steering wheel (<NUM>), in particular during a collision event, is less than a threshold value (Et), the first locking means (<NUM>) incorporating collapsible means (<NUM>) adapted to collapse when the kinetic energy transmitted to the steering wheel (<NUM>) is above said threshold value (Et), thus leading to the displacement of the steering shaft housing unit (<NUM>) from the locked position to a final position, in which at least a part of the kinetic energy transmitted to the steering wheel (<NUM>) has been absorbed by the collapsible means (<NUM>), characterized in that the first locking means (<NUM>) comprise a locking arm (<NUM>) extending between an upper end (<NUM>) pivotally connected to the steering shaft housing unit (<NUM>) and a lower end (<NUM>) pivotally connected to a collapsible element (<NUM>) that is fixedly connected to the supporting bracket (<NUM>), the collapsible element (<NUM>) being configured to collapse under the action of a compression force applied by the locking arm (<NUM>).