FR3135950A1 - steering column for motor vehicle - Google Patents

Abstract

In summary, the invention relates to a steering column (1) comprising a frangible zone making it possible to dissociate an upper bar (11) of the steering column (1) from a lower bar (12) of said steering column (1). ) in the event of an accident, and thus prevent the steering column (1) from rising into the passenger compartment of the motor vehicle. Additionally, the invention relates to a steering assembly (2) comprising the aforementioned steering column (1) and an impactor device (3) making it possible to break the steering column (1) at the frangible zone. Figure to be published with the abstract: Fig. 1

Description

steering column for motor vehicle

The technical context of the present invention is that of the passive safety of the occupants of a motor vehicle, and more particularly the protection of the driver in the event of a frontal impact at high speed. More particularly, the invention relates to a steering column for a motor vehicle.

In the state of the art, we know of steering columns making it possible to control the orientation of the wheels of the motor vehicle in order to control its trajectory. In known manner, such steering columns comprise (i) an upper bar, one free end of which is intended to be fixed integrally to a steering wheel, (ii) a lower bar coupled to the upper bar via a cardan joint. upper, and (iii) an electric power steering motor coupled to the lower bar via a lower gimbal, the electric power steering motor being configured to generate torque at the lower bar.

The free end of these steering columns is located in the passenger compartment of the motor vehicle in order to allow the steering wheel to be fixed and manipulated by the driver of the motor vehicle. On the other hand, the lower bar, the lower universal joint and the electric power steering motor are located outside the passenger compartment, and can in particular be housed partly in the engine compartment of the motor vehicle.

In the event of a frontal impact of the motor vehicle, the forces generated during such an impact are transmitted to a structure of the motor vehicle, and in particular to its body and through the side members. Of course, the energy of the shock leads to a deformation of some of these elements.

In order to meet the approval criteria and guarantee the safety of the occupants of the motor vehicle, it is sought to limit, or even prevent, any intrusion into the passenger compartment. In particular, it is therefore desired that the steering column cannot enter the passenger compartment, which could have very serious consequences on the physical integrity of the driver in particular.

However, in a known manner, the steering columns are rigid in order to be able to safely transmit the torque produced by the driver at the steering wheel and controlled by the electric power steering motor. This rigidity, desired to guarantee reliability of the steering column during its use, can however prove to be penalizing in the event of a high energy frontal impact, since such a steering column, impacted by components of the motor vehicle located in front of it, can push said steering column backwards and cause it to enter the passenger compartment. This results in a backward movement towards the rear of the steering column and an upward movement of said steering column towards the driver's face.

As mentioned previously, these movements are of course unwanted.

The object of the present invention is to propose a new steering column in order to respond at least largely to the previous problems and also to lead to other advantages.

Another aim of the invention is to reduce the penetration of the steering column into the passenger compartment of the motor vehicle in the event of a frontal impact.

Another aim of the invention is to reduce the risk of injury to the driver in the event of a frontal impact.

Another aim of the invention is to improve the safety of the occupants of the passenger compartment of the motor vehicle.

According to a first aspect of the invention, at least one of the aforementioned objectives is achieved with a steering column for a motor vehicle, the steering column comprising (i) an upper bar of which a free end is intended to be fixed integrally to a steering wheel, (ii) a lower bar coupled to the upper bar via an upper universal joint, (iii) an electric power steering motor coupled to the lower bar via a lower universal joint, the motor electric power steering being configured to generate a torque at the level of the lower bar. According to the invention, the steering column comprises a frangible zone forming an incipient rupture and configured to break in the event of an impact – applied to the frangible zone – greater than a threshold value.

In the context of the invention, the upper bar and the lower bar take the form of cylindrical surfaces. They are connected together through a connection allowing the transmission of a torque, induced by the driver by means of the steering wheel at the upper end of the steering column. More particularly, the connection between the upper bar and the lower bar is provided via the upper universal joint.

Analogously, the lower bar and the electric power steering motor are connected to each other through a connection allowing the transmission of a torque, via the lower universal joint.

The electric power steering motor is a motor configured to generate a motor torque on the steering column and, ultimately, on the steering wheels of the motor vehicle, depending on the torque initiated by the driver through the steering wheel. The electric power steering motor is thus coupled in rotation to the steering column, via the lower universal joint.

In the context of the invention, the frangible zone is a programmed rupture zone of the steering column, configured to break – at the frangible zone, if a force, for example shearing or compression, applied to the column direction and/or the frangible zone, exceeds the threshold value.

Of course, the threshold value depends on the motor vehicles and/or the safety constraints specific to each automobile manufacturer, the present invention not being limited to one or the other of these threshold values.

Thus, the steering column conforming to the first aspect of the invention allows, by breaking if a sufficiently strong force is applied to the steering column or to the frangible zone, to break a chain of transmission of the forces resulting from the frontal impact and This prevents the steering column, at its upper part, from being moved towards or into the passenger compartment. Consequently, the safety of the occupants of the motor vehicle is increased.

The steering column conforming to the first aspect of the invention advantageously comprises at least one of the improvements below, the technical characteristics forming these improvements being able to be taken alone or in combination:

- the frangible zone is located near the lower universal joint. By proximity, we understand that the frangible zone is located in a range extending approximately 50 cm above and/or below the lower universal joint. Indeed, it is particularly advantageous to break the steering column near the electric power steering motor to avoid any movement of the upper part of the steering column, including the upper bar and the upper universal joint;

- the frangible zone takes the form of a local thinning of material, so that a thickness of a wall forming the steering column is, at the level of the frangible zone, between 40% and 60% of the thickness of said wall, taken outside of said frangible zone. Preferably, the local thinning of material is such that the thickness of the wall forming the steering column is, at the level of the frangible zone equal to 50% of the thickness of said wall, taken outside said zone frangible. This advantageous configuration makes it possible to define a sufficiently high breaking force to allow normal operation of the steering column under the conditions provided for normal use of the motor vehicle, while allowing the expected breakage in the event of a frontal impact;

- the frangible zone takes the form of a circumferential groove. The circumferential groove extends peripherally all around the steering column, relative to a specific elongation axis of said steering column taken at the level of the frangible zone. In particular, a depth of the circumferential groove is between 3 mm and 5 mm;

- the frangible zone comprises a plurality of perforations in a wall forming the steering column, the perforations being distributed circumferentially around the steering column. The perforations thus make it possible to weaken the steering column at the frangible zone and allow it to break if a force greater than the threshold value is applied to the steering column, at the frangible zone;

- according to a first alternative embodiment, the perforations provided on the wall of the steering column are through, so that the perforations form openings through said wall. According to a second alternative embodiment, the perforations provided on the wall of the steering column form non-opening depressions;

- in the second embodiment, the depressions have an ovoid shape;

- in the second alternative embodiment, the depressions have a height of between 3 mm and 7 mm, preferably equal to 5 mm;

- in the second alternative embodiment, the depressions have a depth of between 2 mm and 4 mm, preferably equal to 3 mm;

- the steering column according to the first aspect of the invention comprises a lower ring and an upper ring fixed integrally on the steering column respectively below and above the frangible zone, the lower ring and the upper ring being fitted onto the steering column and fixed integrally to said steering column so as to create a section discontinuity on said steering column, at the level of the frangible zone. This advantageous configuration thus makes it possible to facilitate the manufacture of such a steering column: the variation in thickness between the frangible zone, of lesser thickness, and the rest of the steering column, of greater thickness, is obtained by assembly and superposition of rings, the upper ring and the lower ring, on the steering column and around the frangible zone, relative to a specific elongation axis of the steering column;

- according to a first preferred embodiment, the frangible zone is located on the lower bar. In other words, the frangible zone is located in an area of the steering column between the lower universal joint and the upper universal joint. According to a second preferred embodiment, the frangible zone is located on a connecting sleeve integrally linked to the electric power steering motor on the one hand, and to the lower universal joint on the other hand. In other words, the frangible zone is located in an area of the steering column between the electric power steering motor and the lower universal joint.

According to a second aspect of the invention, there is proposed a steering assembly for a motor vehicle, the steering assembly comprising (i) a steering column conforming to the first aspect of the invention or according to any of its improvements , and (ii) an impactor device located opposite the frangible zone, the impactor device being configured to be able to impact and cut the steering column at the frangible zone in the event of an impact.

In the context of the present invention, the longitudinal axis, the lateral axis and the vertical axis are defined relative to the motor vehicle on which the steering assembly conforming to the first aspect of the invention is intended to be mounted. More particularly, the transverse axis is understood as a direction taken between a lateral side of the motor vehicle and an opposite lateral side of said motor vehicle. In other words, the transverse axis is understood in a direction which extends from a passenger side of the motor vehicle towards a driver's side of said motor vehicle, or vice versa. The adjectives lateral, interior and exterior refer to such a transverse axis. Additionally, the longitudinal axis extends as being taken along a direction that extends from front to rear or rear to front of the motor vehicle. The longitudinal axis is perpendicular to the transverse axis. The adjectives frontal, front and rear refer to this longitudinal axis. Finally, the vertical axis is understood as being taken along an axis which extends from the wheels of the motor vehicle and towards the roof of said motor vehicle, or vice versa, the vertical axis being simultaneously perpendicular to the axis transverse and to the longitudinal axis. The adjectives above and below, or inferior and superior refer to this vertical axis.

Complementarily, we also define a specific extension axis in the reference frame of the pedal, the specific extension axis being defined by the main direction of elongation of the steering column, taken at the level of the part considered, it is that is to say in particular as defined by the direction of elongation of the lower bar or the upper bar.

In the context of the invention, the impactor device is configured to cut the steering column at the frangible zone. Thus, the impactor device makes it possible to guarantee the correct stress on the frangible zone and to generate the forces necessary for the breakage of the steering column at the level of the frangible zone in the event of a frontal impact on the motor vehicle in which the assembly of direction according to the second aspect of the invention is intended to be mounted.

The steering assembly conforming to the second aspect of the invention advantageously comprises at least one of the improvements below, the technical characteristics forming these improvements being able to be taken alone or in combination:

- according to a first alternative embodiment, the impactor device is integrally fixed to an engine of the motor vehicle;

- according to a second alternative embodiment, the impactor device is integrally fixed to a structural element of the motor vehicle;

- the impactor device is located in front of the steering column, relative to a longitudinal axis of the motor vehicle;

- the impactor device has a prismatic range which extends towards the steering column. The prismatic bearing thus forms a “knife” configured to be able to strike and cut the steering column at the frangible zone in the event of a frontal impact on the motor vehicle;

- a free end of the prismatic bearing has a bevel. The free end is the one located directly opposite the steering column and the frangible zone;

- the impactor device is made of a metal alloy.

According to a third aspect of the invention, there is proposed a motor vehicle comprising a steering assembly conforming to the second aspect of the invention or according to any of its improvements.

Various embodiments of the invention are planned, integrating according to all of their possible combinations the different optional characteristics exposed here.

Other characteristics and advantages of the invention will appear further through the description which follows on the one hand, and several examples of embodiment given for informational and non-limiting purposes with reference to the appended schematic drawings on the other hand, in which :

illustrates a profile view of a steering assembly conforming to the second aspect of the invention;

illustrates a schematic side view of the effect of the steering assembly shown on the ;

illustrates a contextual view of an impacting device of the steering assembly illustrated on the ;

illustrates a detailed view of the impactor device illustrated on the ;

illustrates a side view of a first example of a steering column conforming to the first aspect of the invention;

illustrates a detailed view of the first example of the steering column illustrated on the ;

illustrates a side view of a second example of a steering column conforming to the first aspect of the invention;

illustrates a detailed view of the second example of the steering column illustrated on the ;

illustrates a profile view of a third example of a steering column conforming to the first aspect of the invention;

illustrates a detailed view of the third example of the steering column illustrated on the ;

illustrates a profile view of a fourth example of a steering column conforming to the first aspect of the invention;

illustrates an exploded view of the fourth example of the steering column illustrated on the .

Of course, the characteristics, variants and different embodiments of the invention can be associated with each other, in various combinations, to the extent that they are not incompatible or exclusive of each other. It will be possible in particular to imagine variants of the invention comprising only a selection of characteristics described subsequently in isolation from the other characteristics described, if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention from to the prior art.

In particular, all the variants and all the embodiments described can be combined with each other if nothing opposes this combination on a technical level.

On the FIGURES, elements common to several FIGURES retain the same reference.

With reference to FIGURES 1 and 5 to 12, the invention relates to a steering column 1 for a motor vehicle, the steering column 1 comprising:

- an upper bar 11, preferably cylindrical in shape, of which a free end 33 is intended to be fixed integrally to a steering wheel;

- a lower bar 12, of preferably cylindrical shape, coupled to the upper bar 11 via an upper universal joint 13. The upper universal joint 13 allows the transmission of a torque, induced by the driver by means of the steering wheel to the level of the upper end of the steering column 1, between the upper bar 11 and the lower bar 12;

- an electric power steering motor 5 coupled to the lower bar 12 via a lower universal joint 14, the electric power steering motor 5 being configured to generate a torque at the level of the lower bar 12. The lower universal joint 14 allows the transmission of the torque generated by the electric power steering motor 5, between the lower bar 12 and said electric power steering motor 5;

- a frangible zone 6 forming an incipient rupture and configured to rupture in the event of an impact – applied to the frangible zone 6 – greater than a threshold value. The frangible zone 6 is a programmed rupture zone of the steering column 1, configured to break – at the level of the frangible zone 6 – if a force, for example shearing or compression, applied to the steering column 1 and/or or frangible zone 6, exceeds the threshold value.

The threshold value depends on the motor vehicles and/or the safety constraints specific to each automobile manufacturer, the present invention not being limited to one or the other of these threshold values.

Several examples of implementation are illustrated in the different FIGURES:

– in FIGURES 5 and 6, the frangible zone 6 is located near the lower universal joint 14, and more particularly in an area located between the lower dial and the electric power steering motor 5. In particular, the frangible zone 6 is here located at the level of a connecting sleeve 51 integrally linked to the electric power steering motor on the one hand, and to the lower universal joint 14 on the other hand. The frangible zone 6 takes the form of a local thinning 61 of material, so that a thickness of a wall forming the steering column 1 is, at the level of the frangible zone 6, between 40% and 60% of the thickness of said wall, taken outside said frangible zone 6. More particularly, and as visible on the , the frangible zone 6 takes the form of a circumferential groove 62 extending peripherally all around the steering column 1, relative to a specific elongation axis of said steering column 1 taken at the level of the frangible zone 6. A depth of the circumferential groove 62 is between 3 mm and 5 mm;

- in the , the frangible zone 6 is identical to that illustrated in FIGURES 5 and 6, but the frangible zone 6 further comprises a plurality of perforations 63 of a wall forming the steering column 1, the perforations 63 being distributed circumferentially around the steering column 1. The perforations 63 are through, so as to form openings through said wall, or the perforations 63 are non-opening, so as to form simple depressions on said wall. The depressions preferably have an ovoid shape and extend across the circumferential groove 62, parallel or substantially parallel to the proper elongation axis of the steering column 1 taken at the level of the frangible zone 6;

– in FIGURES 8 and 9, the frangible zone 6 is located near the lower universal joint 14, and more particularly in an area located between the lower dial and the lower bar 12 of the steering column 1. In particular, the frangible zone 6 is here located at a lower end of the lower bar 12 or at an upper end of the lower universal joint 14. The frangible zone 6 takes the form of a local thinning 61 of material, so that a thickness of a wall forming the steering column 1 or, at the level of the frangible zone 6 between 40% and 60% of the thickness of said wall, taken outside said frangible zone 6. More particularly, and as visible on there , the frangible zone 6 takes the form of a circumferential groove 62 extending peripherally all around the steering column 1, relative to a specific elongation axis of said steering column 1 taken at the level of the frangible zone 6. A depth of the circumferential groove 62 is between 3 mm and 5 mm;

- in the , the frangible zone 6 is identical to that illustrated in FIGURES 8 and 9, but the frangible zone 6 further comprises a plurality of perforations 63 of a wall forming the steering column 1, the perforations 63 being distributed circumferentially around the steering column 1. The perforations 63 are through, so as to form openings through said wall, or the perforations 63 are non-opening, so as to form simple depressions on said wall. The depressions preferably have an ovoid shape and extend across the circumferential groove 62, parallel or substantially parallel to the proper elongation axis of the steering column 1 taken at the level of the frangible zone 6;

– in FIGURES 11 and 12, the frangible zone 6 is formed by a discontinuous variation in thickness of the steering column 1, variation in thickness obtained by adding and assembling a lower ring 65 and an upper ring 64 fixed integrally on the steering column 1 respectively below and above the frangible zone 6. The lower ring 65 and the upper ring 64 are fitted onto the steering column 1 and fixed integrally to said steering column 1 so as to create a section discontinuity on said steering column 1, at the level of the frangible zone 6. Thus, the variation in thickness between the frangible zone 6, of lesser thickness, and the rest of the steering column 1, of greater thickness , is obtained by assembly and superposition of rings, the upper ring and the lower ring, on the steering column 1 and around the frangible zone 6, relative to a specific elongation axis of the steering column 1.

In reference to the , the invention also relates to a steering assembly 2 comprising:

- a steering column 1 as described above in any of its variant embodiments;

- an impactor device 3 located opposite the frangible zone 6, the impactor device 3 being configured to be able to impact and cut the steering column 1 at the level of the frangible zone 6 in the event of an impact.

The impactor device 3 is configured to cut the steering column 1 at the level of the frangible zone 6. For this purpose, the impactor device 3 is located in front of the steering column 1, relative to a longitudinal axis of the motor vehicle. The impactor device 3 is integrally fixed to a structural element of the motor vehicle distinct from the steering column 1 and/or the electric power steering motor 5, so that, in the event of a front impact of the motor vehicle, the impactor device 3 can present a non-zero relative longitudinal movement with respect to the steering column 1, taken at the level of the frangible zone 6. Preferably, the impactor device 3 is fixed integrally to an engine of the motor vehicle.

As visible in FIGURES 3 and 4, the impactor device 3 comprises a base 31 and a prismatic surface 32 which extends projecting from the base 31 and in the direction of the steering column 1. The prismatic surface 32 thus forms a “ knife” configured to be able to strike and cut the steering column 1 at the frangible zone 6 in the event of a frontal impact on the motor vehicle. For this purpose, a free end 33 of the prismatic bearing surface 32, located directly opposite the steering column 1 and the frangible zone 6, has a bevel in order to effectively section the steering column 1.

In summary, the invention relates to a steering column 1 comprising a frangible zone 6 making it possible to dissociate an upper bar 11 of the steering column 1 from a lower bar 12 of said steering column 1 in the event of an accident, and thus avoid a rise of the steering column 1 in the passenger compartment of the motor vehicle. Complementarily, the invention relates to a steering assembly 2 comprising the aforementioned steering column 1 and an impactor device 3 making it possible to break the steering column 1 at the frangible zone 6.

Of course, the invention is not limited to the examples which have just been described and numerous adjustments can be made to these examples without departing from the scope of the invention. In particular, the different characteristics, shapes, variants and embodiments of the invention can be associated with each other in various combinations to the extent that they are not incompatible or exclusive of each other. In particular, all the variants and embodiments described above can be combined with each other.

Claims (10)

Steering column (1) for a motor vehicle, the steering column (1) comprising:
- an upper bar (11) of which a free end (33) is intended to be fixed integrally to a steering wheel;
- a lower bar (12) coupled to the upper bar (11) via an upper universal joint (13);
- an electric power steering motor (5) coupled to the lower bar (12) via a lower universal joint (14), the electric power steering motor (5) being configured to generate a torque at the lower bar (12);
characterized in that the steering column (1) comprises a frangible zone (6) forming an incipient rupture and configured to break in the event of an impact – applied to the frangible zone (6) – greater than a threshold value. Steering column (1) according to the preceding claim, in which the frangible zone (6) is located near the lower universal joint (14). Steering column (1) according to any one of the preceding claims, in which the frangible zone (6) takes the form of a local thinning (61) of material, so that a thickness of a wall forming the column of direction (1) or, at the level of the frangible zone (6) between 40% and 60% of the thickness of said wall, taken outside of said frangible zone (6). Steering column (1) according to the preceding claim, in which the frangible zone (6) takes the form of a circumferential groove (62). Steering column (1) according to any one of claims 3 or 4, in which the frangible zone (6) comprises a plurality of perforations (63) of a wall forming the steering column (1), the perforations (63 ) being distributed circumferentially around the steering column (1). Steering column (1) according to any one of the preceding claims, in which the steering column (1) comprises a lower ring (65) and an upper ring (64) fixed integrally on the steering column (1) respectively in below and above the frangible zone (6), the lower ring (65) and the upper ring (64) being fitted onto the steering column (1) and fixed integrally to said steering column (1) so as to create a section discontinuity on said steering column (1), at the level of the frangible zone (6). Steering column (1) according to any one of claims 1 to 6, in which the frangible zone (6) is located on the lower bar (12). Steering column (1) according to any one of claims 1 to 6, in which the frangible zone (6) is located on a connecting sleeve (51) integrally linked to the electric power steering motor (5) on the one hand , and to the lower gimbal (14) on the other hand. Steering assembly (2) for a motor vehicle, the steering assembly (2) comprising:
- a steering column (1) according to any one of the preceding claims;
- an impactor device (3) located opposite the frangible zone (6), the impactor device (3) being configured to be able to impact and cut the steering column (1) at the level of the frangible zone (6) in the event of shock. Motor vehicle comprising a steering assembly (2) according to the preceding claim.