Steering assembly for motor vehicle

Abstract

The invention relates to a steering assembly (1) for a motor vehicle, the steering assembly (1) comprising: a steering rack (13) connected to a lower end (112) of a steering column (11) by means of a coupling member (14), said rack (13) being held in engagement against a lower face of an oblique section (123) of a cradle (12) extending under an engine compartment (19) by sliding tracks (16) fixed integrally to said lower face of the cradle (12) by fixing screws. The rack (13) and / or the associated fixing screws form fusible fixing means (15) programmed to break from a predetermined mechanical stress, in the event of a frontal impact of the motor vehicle. Figure to be published with the abstract: Fig. 1

Description

Title of the invention: Steering assembly for a motor vehicle

[0001] The technical context of the present invention is that of devices for connecting a motor vehicle to the ground, and in particular devices for ensuring the safety of the occupants of the motor vehicle and reducing damage caused to the motor vehicle in the event of an accident, in particular to its steering column. More particularly, the invention relates to a steering assembly for a motor vehicle.

[0002] In the state of the art, steering assemblies are known comprising a steering rack, which is mounted in translation in a coupling member fixed to a chassis of the vehicle, and whose lateral ends are each connected, by means of a steering rod, to a steering knuckle carrying a steered wheel, so that the translational movement of the rack causes the modification of a steering angle of said steered wheels.

[0003] Such steering assemblies also comprise a steering column, a lower end of which is provided with the coupling member which meshes with the steering rack, and an upper end of which is provided with a steering wheel which allows a driver installed in the passenger compartment of the motor vehicle to maneuver such steering assemblies in order to steer the steered wheels - and ultimately the motor vehicle - in the desired direction.

[0004] In a known manner, such steering assemblies are generally housed in the engine compartment located at the front of the motor vehicle, the steering column extending under the engine compartment. At its lower end, the steering column is securely attached to a cradle of the motor vehicle. In a known manner, since the steering column reaches the cradle from above and from behind, it is often securely attached to the cradle "from above", so that the cradle is located below the steering column and the rack.

[0005] It has been observed that this configuration is not optimal in the event of a frontal impact, because it causes various elements to be pushed backwards - including the cradle itself, the steering rack or even the traction motor of the motor vehicle. Such a push is not desired because it generates possible intrusions into the passenger compartment which, in turn, significantly degrade the safety of the occupants.

[0006] In particular, in the event of a frontal impact, the current arrangement of the rack, the cradle and the lower part of the steering column lead to a transmission of the forces resulting from the frontal impact into the steering column which then moves back towards the passenger compartment. This situation is not desired.

[0007] The object of the present invention is to provide a new steering assembly in order to address at least a large part of the above problems and to further lead to other advantages.

[0008] Another aim of the invention is to improve the safety of the occupants of the passenger compartment of the motor vehicle in the event of a frontal impact.

[0009] Another object of the invention is to reduce the risk of the steering column sinking in the event of a frontal impact.

[0010] Another aim of the invention is to propose a simple and economical architecture.

[0011] According to a first aspect of the invention, at least one of the aforementioned objectives is achieved. with a steering assembly for a motor vehicle, the steering assembly comprising:

[0012] - a rack linked to steering ball joints of the vehicle's steering wheels car by means of steering rods;

[0013] - a steering column extending from a steering wheel located in a passenger compartment of the motor vehicle and the rack, the steering column being coupled to the rack by means of a member;

[0014] - a cradle extending from the passenger compartment and below a traction motor of the motor vehicle, the steering column extending below the traction motor.

[0015] In the steering assembly according to the first aspect of the invention, the rack and the steering column integral with the rack are fixed to a lower face of the cradle by fusible fixing means.

[0016] In the context of the present invention, the fusible fastening means are configured to yield in the event of an impact greater than a predetermined intensity. For this purpose, the fastening means are dimensioned to break beyond a certain threshold of mechanical stresses. By such dimensioning, it is understood that the dimensions of the fastening means and the material chosen are such that they make it possible to predetermine a stress level beyond which the fastening means yield. This stress level is such that, for normal use of the motor vehicle on which the steering assembly is intended to be mounted, the fastening means remain intact. On the other hand, in the event of a frontal impact resulting in the sinking of the elements of the motor vehicle located in front of the steering assembly, then the transmission of the mechanical forces resulting from this frontal impact into the steering assembly according to the invention leads to a breakage of the fastening means.Optionally, the fastening means include a rupture zone configured to rupture in the event of a frontal impact.

[0017] In the context of the present invention, the lower face of the cradle is a face said cradle which is located below, that is to say facing the ground when the steering assembly is installed on a motor vehicle. In other words, the lower face of the cradle is the face of said cradle which is located opposite the traction motor.

[0018] In the context of the present invention, the coupling member is configured to transmit the rotational torque introduced by the user at the steering wheel to the rack, so as to induce pivoting of the steered wheels. By way of non-limiting example, the coupling member is of the steering pinion type.

[0019] In the context of the present invention, the cradle extends along a longitudinal axis of the motor vehicle.

[0020] In the context of the present invention, the longitudinal axis, a lateral axis and a vertical axis are defined relative to the motor vehicle on which the steering assembly according 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 as a direction which extends from a passenger side of the motor vehicle to a driver's side of said motor vehicle, or vice versa. The adjectives lateral, inboard and outboard refer to such a transverse axis. Furthermore, the longitudinal axis extends as being taken along a direction which extends from front to rear or from back 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 to be taken along an axis that 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 transverse axis and to the longitudinal axis. The adjectives above and below, or lower and upper refer to this vertical axis.

[0021] Thus, the steering assembly according to the first aspect of the invention solves the technical problem in that it allows the steering column and / or the rack to detach from the cradle in the event of a frontal impact, the fixing means giving way under the effect of said frontal impact. Subsequently, under the effect of gravity, the lower and frontal part of the steering column falls towards the ground, thus reducing its depression towards the passenger compartment. This clever configuration makes it possible, on the one hand, to separate the steering column from the transmission chain from the forces resulting from the frontal impact - at least at the level of its lower and frontal part - and, on the other hand, to reduce the size of the steering rack in the event of a frontal impact.

[0022] In the context of the present invention, the fixing means thus form programmed breaking fixing means, making it possible to “fall” either the part front and lower part of the steering column, alone, or, alternatively or in addition, the rack.

[0023] The steering assembly according 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:

[0024] - the fixing means comprise at least one sliding track of the cre rack relative to the cradle, the at least one sliding track forming a fixing lug making it possible to keep the rack engaged between the sliding track and the cradle. The sliding track is fixed securely to the cradle by any means, and in particular by any fusible means;

[0025] - the fusible fixing means comprise at least one fixing screw connecting the steering column and / or the rack to the cradle, the at least one fixing screw being configured to break when it is subjected to a mechanical stress greater than a threshold value. More particularly, the at least one fixing screw forming the fusible fixing means connects the sliding track of the rack to the cradle, said rack being held in an intermediate position between the sliding track and the cradle. As explained previously, the threshold value is here chosen so that the at least one fixing screw remains intact for normal use of the motor vehicle intended to be equipped with the steering assembly according to the invention, and so that said at least one fixing screw breaks in the event of a sufficiently significant frontal impact;

[0026] - according to a preferred embodiment of the invention, the rack is fixed to a oblique section of the cradle by means of at least one sliding track holding the rack engaged between said sliding track and the lower face of the oblique section of the cradle, said at least one sliding track being fixed to the oblique section of the cradle by the fusible fixing means;

[0027] - possibly, the steering column is linked to the rack by a face in lower face of the rack, and the steering column is securely fixed to the cradle by the fusible fixing means. In the context of the present invention, the lower face of the rack is a face of said rack which is located below, that is to say facing the ground when the steering assembly is installed on a motor vehicle. In other words, the lower face of the rack is the face of the rack which is located opposite the traction motor;

[0028] - the cradle comprises (i) a rear section which extends partly under the passenger compartment of the motor vehicle, (ii) a front section extending beneath an engine compartment of the motor vehicle, the front section being located in a raised position relative to the rear section, and (iii) an oblique section extending between the front section and the rear section, the oblique section having an inclined orientation. This advantageous configuration makes it possible to “guide” the rack and / or the lower part of the steering column downwards in the event of a frontal impact and rupture of the fusible fixing means. More generally, the inclined orientation of the oblique section introduces a vertical component in the event of movement against said oblique section, making it possible to shift the rack and / or the lower part of the steering column downwards, and thus limiting the latter’s recoil towards the passenger compartment. In particular, the oblique section has an inclined orientation relative to the front section and / or the rear section. The front section and / or the rear section extend horizontally;

[0029] - the oblique section of the cradle is inclined at an angle between 20° and 60°. The angle of inclination of the oblique section of the cradle is measured relative to a horizontal plane or relative to the rear section of the cradle;

[0030] - the rack is fixed to the oblique section of the cradle. This configuration advantageous configuration allows to induce a downward movement of the lower part of the steering column and / or the rack, in the event of a frontal impact and breakage of the fixing means. Obviously, in this advantageous configuration, the means for fixing the steering column and / or the rack to the oblique section of the cradle are located on said oblique section of the cradle. In particular, the coupling member of the steering column on the rack is integral with the cradle, and preferably with the oblique section.

[0031] According to a second aspect of the invention, there is provided a motor vehicle comprising a steering assembly in accordance with the first aspect of the invention or according to any of its improvements.

[0032] Various embodiments of the invention are provided, integrating according to all of their possible combinations the different optional characteristics set out here.

[0033] Other characteristics and advantages of the invention will become apparent from the following description on the one hand, and from several examples of embodiment given for informational and non-limiting purposes with reference to the attached schematic drawings on the other hand, in which:

[0034] [Fig. 1] illustrates a schematic and profile view of the steering assembly according to the first aspect of the invention, during normal use of a motor vehicle on which it is mounted;

[0035] [Fig.2] illustrates a schematic and top view of the connection between the rack and the steering column of the steering assembly shown in [Fig.l];

[0036] [Fig.3] illustrates a schematic and profile view of the steering assembly according to the first aspect of the invention, during a frontal impact involving a com- longitudinal pressure towards the rear of said steering assembly.

[0037] Of course, the features, variants and different embodiments of the invention may be combined with each other, in various combinations, provided that they are not incompatible or mutually exclusive. In particular, variants of the invention may be imagined comprising only a selection of features described below in isolation from the other features described, if this selection of features is sufficient to confer a technical advantage or to differentiate the invention from the prior art.

[0038] In particular, all the variants and all the embodiments described can be combined with each other if nothing prevents this combination from a technical point of view.

[0039] In the figures, the elements common to several figures retain the same reference.

[0040] In the FIGURES described below, a longitudinal axis X, a lateral axis and a vertical axis Z are defined relative to the motor vehicle on which the compliant steering assembly 1 is intended to be mounted.

[0041] 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 to a driver's side of said motor vehicle, or vice versa. The adjectives lateral, interior and exterior refer to such a transverse axis.

[0042] Furthermore, the longitudinal axis X extends as taken along a direction that extends from front to rear or from back to front of the motor vehicle. The longitudinal axis X is perpendicular to the transverse axis. The adjectives frontal, front and rear refer to this longitudinal axis X.

[0043] Finally, the vertical axis Z 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 Z being simultaneously perpendicular to the transverse axis and to the longitudinal axis X. The adjectives above and below, or lower and upper refer to this vertical axis Z.

[0044] With reference to FIGURES 1 to 3, the invention relates to a steering assembly 1 for a motor vehicle, the steering assembly 1 comprising:

[0045] - a rack 13 linked to steering ball joints of the vehicle's steering wheels automobile via steering rods 20;

[0046] - a steering column 11 which extends from a steering wheel located in a passenger compartment 2 of the motor vehicle and the rack 13, the steering column 11 being coupled to the rack 13 by means of a member;

[0047] - a cradle 12 which extends from the passenger compartment 2 and below a traction motor 18 of the motor vehicle, the steering column 11 extending under the traction motor 18.

[0048] In the steering assembly 1 according to the first aspect of the invention, the rack 13 and the steering column 11 secured to the rack 13 are fixed to a lower face of the cradle 12 by fusible fixing means 15.

[0049] The traction motor 18 is housed in an engine compartment 19, at the front of the passenger compartment 2 relative to the longitudinal axis X. The engine compartment 19 is separated from the passenger compartment 2 by an apron 17 which extends in front of the passenger compartment 2. The cradle 12 extends essentially along the longitudinal axis X, from the passenger compartment 2 to the engine compartment 19. In particular, the cradle 12 extends in a lower part of the engine compartment 19 and below a floor of the passenger compartment 2.

[0050] For this purpose, the cradle 12 comprises:

[0051] - a rear section 121 which extends along the longitudinal axis X under the passenger compartment 2 of the motor vehicle;

[0052] - a front section 122 which extends along the longitudinal axis X under the compartment engine 19 of the motor vehicle, the front section 122 being located in a raised position relative to the rear section 121, relative to the vertical axis Z; and

[0053] - an oblique section 123 which extends between the front section 122 and the rear section 121, the oblique section 123 having an inclined orientation.

[0054] According to the invention, the oblique section 123 of the cradle 12 extends simultaneously along the longitudinal axis X and along the vertical axis Z, so as to be located, close to the front section 122, in a raised manner at a proximal part of the rear section 121. The oblique section 123 of the cradle 12 is inclined at an angle of between 20° and 60°. The angle of inclination of the oblique section 123 of the cradle 12 is measured relative to a horizontal plane or relative to the rear section 121 of the cradle 12;

[0055] According to the invention, the lower face of the cradle 12 on which the rack 13 and the lower part of the steering column 11 are attached is a face of said cradle 12 which is located on a lower part of the cradle 12, that is to say facing the ground when the steering assembly 1 is installed on a motor vehicle. In other words, the lower face of the cradle 12 is the face of said cradle 12 which is located opposite the traction motor 18 and the engine compartment 19.

[0056] Thus, as visible in [Fig. 3], in the event of a frontal impact OBST and sufficiently strong mechanical stresses at the level of the fusible fixing means 15, the rupture of the latter leads to a release of the rack 13 and of the lower end 112 of the steering column 11, these being then able to fall towards the ground by simple gravitational effect. This fall along the vertical axis Ze leads to a more pronounced inclination of the steering column 11 thus released from the cradle 12 and allows it to be detached - at least partially - from the transmission chain of the forces resulting from the frontal impact OBST: the steering column 11 is less stressed by the longitudinal depression towards the rear of the various constituent elements of the steering assembly 1, thus limiting the depression in the passenger compartment 2 and preserving the physical integrity of both said passenger compartment 2 and its occupants. The oblique section 123 of the cradle 12 makes it possible to promote this downward movement, relative to the vertical axis Z, of the rack 13 and the lower end 112 of the steering column 11. This results in a displacement F of the steering column 11 along the horizontal axis and towards the rear which is less, in the event of a frontal impact OBST.

[0057] In order to allow such behavior and to lead to the advantages of the present invention, it is necessary that the rack 13 is linked to the cradle 12 both:

[0058] - by fusible fixing means 15, that is to say programmed to break at from a pre-programmed mechanical stress threshold determined based on frontal impact scenarios;

[0059] - at the level of the lower part of the cradle 12, so as to be able to fall towards the down by simple gravitational effect without being hindered in its fall by the cradle 12 itself.

[0060] As visible in [Fig.2], the fixing means 15 comprise at least one sliding track 16 of the rack 13 relative to the cradle 12, the at least one sliding track 16 forming a fixing lug making it possible to keep the rack 13 engaged between the sliding track 16 and the cradle 12. Preferably, the rack 13 is held against the lower face of the cradle 12 by means of two sliding tracks 16 each located at two lateral ends of said rack 13.

[0061] The sliding track 16 is fixedly attached to the cradle 12 by any means, and in particular by any fusible means. Thus, according to the invention, the fusible fixing means 15 comprise both the sliding track 16 and the screw for fixing said sliding track 16 to the lower face of the cradle 12. In the event of a frontal impact OBST, the sliding track 16 and / or the fixing screw breaks and thus releases the steering column 11 at its lower end 112.

[0062] It is also recalled that, the steering column 11 being articulated by one or more universal joints between its upper end 111 and its lower end 112, the release of its lower end 112 from the lower face of the oblique section 123 of the cradle 12 during a frontal impact OBST and the rupture of the fusible fixing means 15 causes said steering column 11 to pivot at the level of one and / or the other of its universal joints, facilitating its downward inclination and reducing the risk of sinking towards the interior of the passenger compartment 2.

[0063] In summary, the invention relates to a steering assembly 1 for a motor vehicle, the steering assembly 1 comprising: a steering rack 13 connected to a lower end 112 of a steering column 11 by means of a coupling member 14, said rack 13 being held in engagement against a lower face of an oblique section 123 of a cradle 12 extending under an engine compartment 19 by sliding tracks (16) fixed integrally to said lower face of the cradle 12 by fixing screws. The rack 13 and / or the associated fixing screws form fusible fixing means 15 programmed to break from a predetermined mechanical stress, in the event of a frontal impact OBST of the motor vehicle.

[0064] 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, forms, variants and embodiments of the invention can be associated with each other in various combinations insofar as they are not incompatible or mutually exclusive. In particular, all the variants and embodiments described above can be combined with each other.

Claims

Claims

1. Steering assembly (1) for a motor vehicle, the steering assembly (1) comprising: - a rack (13) connected to steering ball joints of steered wheels of the motor vehicle by means of steering rods (20) - a steering column (11) which extends from a steering wheel located in a passenger compartment (2) of the motor vehicle and the rack (13), the steering column (11) being coupled to the rack (13) by means of a coupling member (14); - a cradle (12) which extends from the passenger compartment (2) and below a traction motor (18) of the motor vehicle, the steering column (11) extending below the traction motor (18); characterized in that the rack (13) and the steering column (11) integral with the rack (13) are fixed to a lower face of the cradle (12) by fusible fixing means (15).

2. Steering assembly (1) according to the preceding claim, in which the fusible fixing means (15) comprise at least one fixing screw connecting the rack (13) to the cradle (12), the at least one fixing screw being configured to break when it is subjected to a mechanical stress greater than a threshold value.

3. Steering assembly (1) according to any one of the preceding claims, wherein the cradle (12) comprises: - a rear section (121) which extends partly under the passenger compartment (2) of the motor vehicle; - a front section (122) which extends under an engine compartment (19) of the motor vehicle, the front section (122) being located in a raised position relative to the rear section (121); - an oblique section (123) which extends between the front section (122) and the rear section (121), the oblique section (123) having an inclined orientation.

4. Steering assembly (1) according to the preceding claim, in which the oblique section (123) of the cradle (12) is inclined at an angle of between 20° and 60°.

5. Steering assembly (1) according to any one of claims 3 or 4, wherein the rack (13) is fixed to the oblique section (123) of the cradle (12).

6. Steering assembly (1) according to any one of claims 3 to 5, wherein the rack (13) is fixed to the oblique section (123) of the cradle (12) by means of at least one sliding track (16) keeping said rack (13) engaged between said sliding track (16) and the lower face of the oblique section (123) of the cradle (12), said at least one sliding track (16) being fixed to the oblique section (123) of the cradle (12) by the fusible fixing means (15).

7. Motor vehicle comprising a steering assembly (1) according to any one of the preceding claims.

Images