WO2008059016A1

WO2008059016A1 - Steering system for automobile vehicle

Info

Publication number: WO2008059016A1
Application number: PCT/EP2007/062386
Authority: WO
Inventors: Mathieu Meynet; Philippe Alcon; Jean-Paul Delmas; Christophe Bouet
Original assignee: Renault S.A.S.
Priority date: 2006-11-17
Filing date: 2007-11-15
Publication date: 2008-05-22
Also published as: FR2908722B1; FR2908722A1

Abstract

Te system of the invention includes a steering axle bearing connected through a pivot link to the wheel axle (ra, Rb) of a vehicle, as well as a first actuator (1a, 1b) driven by a monitoring and control circuit (100) adapted for controlling the steering orientation of the wheel (Ra, Rb). According to the invention, the system further includes a second actuator (2a, 2b) also driven by a monitoring and control circuit and adapted to modify the camber angle of said wheel (Ra, Rb). Application in automotive construction.

Description

STEERING SYSTEM FOR MOTOR VEHICLE

The present invention relates to a steering system for a motor vehicle.

It relates more specifically to a steering system of the type usually referred to as "steer by wire". In a system of this kind, unlike the traditional system, the steering wheel does not control the orientation of the steering wheels of the vehicle via a mechanical transmission.

This control is performed by means of actuators, such as electric cylinders in particular, which are controlled by a control and control circuit controlled by the angular position of the steering wheel (which is permanently detected by appropriate sensors), and this in function of different parameters and a predefined program.

Such a system eliminates the clutter of certain mechanical devices, which frees up space in the engine trunk of the vehicle, and improves safety due to the removal of the steering column, which can pose problems. Shock problems for the driver especially in the event of a frontal collision of the vehicle.

The state of the art in the art can be illustrated by documents FR-A 2 812 264, EP 1 669 275 and FR 2 879 153. The invention is more particularly directed to a system in which each of the steering wheels is operated independently of the other - or others - without a mutual mechanical connection.

The system which is the subject of the present invention comprises a directional hub door which is integral with the hub of a wheel of the vehicle, and a first actuator controlled by a control and control circuit, and adapted to control the Directional orientation of the wheel.

A first object of the invention is to propose a system of this kind which makes it possible, in addition to the directional control, to act on the camber of the wheel, that is to say on the angle formed by the axis of the wheel. the wheel relative to the support plane - assumed horizontal - of the wheel, which plane substantially corresponds to the ground on which the wheel rests. For this purpose, and in accordance with the invention, the steering system comprises a second actuator which is also controlled by a control and control circuit, and is adapted to modify the camber angle of the wheel.

Both actuators are advantageously electric cylinders. They can be controlled independently of each other, simultaneously or not, according to certain parameters related to the driving conditions, these actuators each receiving in real time instructions issued by the control and control circuit so as to optimize the performance of the vehicle, as well as the comfort and safety of the driver and, where appropriate, his passengers.

It should be noted that document US Pat. No. 4,971,348 discloses a system for controlling the camber of the wheel of a motor vehicle.

However, in this known system, the camber of the non-directional rear wheels is varied according to the steering angle of the front wheels, which are directional. The system can not be transposed to directional wheels.

Another object of the invention is to provide an arrangement in which actuators are relatively close to the wheel, so as to best free space inside the engine trunk adjacent. For this, particularly advantageously, on the one hand the hub carrier member is a rod whose lower part is fixed to the hub inside the inner cavity of the wheel web and which is shaped so as to bypass the tire. of the wheel inwards and upwards, so that its upper part is above the wheel and, secondly, the second actuator acts on this upper part.

An additional object of the invention is to provide a solution in which the hub actuation system fits suitably within a steering train, particularly within a double-wishbone steering train. For this purpose, the upper triangle comprises a deformable arm in which is integrated said second actuator, this arm being articulated at one of its ends to a fixed part of the vehicle, and at its other end, via a pivot, to said part upper hub door.

Moreover, according to a number of advantageous but nonlimiting features of the invention: this deformable arm comprises a set of links articulated to a fixed part of the vehicle, as well as a stirrup itself articulated on this set of links, the body of the second actuator being articulated in the links, whereas its rod is connected by an articulation to said stirrup, and the latter being connected via said pivot to the upper part of the hub carrier;

- The lower triangle is embodied by a pair of independent arms, articulated at one end to a fixed part of the vehicle, and at the other end to the lower part of the hub carrier;

- One of said arm supports, in its central zone, a damper whose upper portion serves as a support for a fixed portion of the vehicle frame;

said first actuator also acts, via a pivot, on the upper part of the hub carrier;

said first actuator acts on the lower part of the hub carrier, in the vicinity of the wheel axle; said first actuator is an electric jack whose body is fixed to a fixed part of the chassis of the vehicle by means of a universal joint, and whose rod is connected via a pivot to the hub carrier.

Other features and advantages of the invention will become apparent from the following description and the accompanying drawings which show possible embodiments thereof. On the drawings:

Figure 1 is a block diagram illustrating the general principle of operation of the system.

Figure 2 is a simplified schematic perspective, with parts broken away, of a system according to the invention.

Figure 3 is a perspective top view of the same system. Figure 4 is a partial and simplified view, also in perspective, of the upper part of the system.

Figure 5 is a top view of the system, the wheel being oriented in the longitudinal direction of the vehicle, which corresponds to a vehicle driving situation in a straight line.

FIGS. 5A and 5B are views similar to that of FIG. 5, showing steering of the wheel on one side and the other.

Figures 6 and 7 are detail and side views of the second actuator, in this case the camber actuator, the latter being integrated in an armature acting as an upper suspension triangle; in Figures 6 and 7 the actuator is shown respectively in the retracted state and in extension.

Figures 8 and 9 are views of the other side of the system and the wheel, with the actuator respectively extended and retracted. Figures 10 and 11 are partial and simplified views similar to those of Figures 8 and 9 respectively, which show a variant of the device ensuring the control of the camber.

Fig. 12 is a side view of the system, including a variant of the device providing directional control, i.e. steering of the wheel.

The block diagram of FIG. 1 is similar to that forming the subject of FIG. 2 of document EP 1 669 275 mentioned above, which it completes in order to add to it the basic elements peculiar to the present invention.

In this figure, the reference is designated P the median longitudinal vertical plane of the vehicle, the references Ra and Rb representing a pair of steering wheels which are arranged symmetrically on each side of this plane P.

The wheels Ra and Rb are for example the front wheels of a motor vehicle.

However, the invention is also applicable to rear and / or non-driving directional wheels.

The diagram of FIG. 1 makes it possible to explain the operation of a "steer by wire" type steering system, as explained in the preamble of the present description.

References 1a and 1b represent the actuators, for example electric or hydraulic cylinders, which are adapted to control the directional orientation, that is to say the deflection of each wheel Ra, respectively Rb.

Each of these actuators is supplied with energy by an independent power supply means or by a common power supply means. An emergency power supply may also be provided.

The control assembly of the actuators 1a and 1b as shown diagrammatically in FIG. 1 comprises an information transmission chain 100 starting from the conductor 101 in order to control the appropriate deflection of the wheels of the vehicle Ra and Rb. The information 100 is collected by a human machine interface

"HMI" 102 (steering wheel and steering wheel position sensor), which is connected to a retriever 103 which transmits the instruction to the driver 104 to a management strategy management system 105.

The latter controls the supply of actuators 1a and 1b via power circuits 106a and 106b dedicated to each actuator. According to the invention, at each wheel Ra and Rb is associated an additional actuator, or second actuator, 2a and 2b, which is also powered by a suitable power supply and which is controlled by the same information channel, via the power electronics 106a, respectively 106b.

However, it would not be outside the scope of the invention to control the second actuators 2a and 2b from a control and control circuit independent of that which drives the first actuators Ia and Ib.

According to the invention, and as will be described in detail below, the actuators 2a and 2b have the function of controlling the camber of the wheels Ra and respectively Rb. The second actuators 2a and 2b are advantageously electric or hydraulic cylinders.

In Figure 2 is shown very schematically a system according to the invention; the body of the motor vehicle is located on the left of Figure 2, while the wheel (not shown) associated with the system is located on the right of the figure.

The main components of this system are the first and second actuators 1, respectively 2, a directional hub carrier 3, the wheel shaft 4, an upper suspension triangle consisting of two elements 5, 6 hinged one on the another, a shock absorber 7, and a lower suspension triangle consisting of two independent rods 8 and 9.

The directional hub carrier 3 has the general shape of a flat rod twisted so as to have, viewed from the side, approximately the shape of a question mark (see Figure 12 in particular).

The lower part of the hub carrier 3 has been designated by the reference 30; this part is fixed to the hub by any suitable means possible, for example by bolting or welding.

In this part is formed an opening 300 which is traversed by the wheel shaft 4.

This transmits the rotational movement of the motor to the wheel via a universal joint joint of known type (constant velocity joint), not shown, which allows the multidirectional pivoting of the wheel. 31 has designated the twisted and arched central part of the hub carrier 3, and by reference 32 its upper end portion, which is approximately in the shape of a substantially horizontal plate, able to position itself above wheel. As already mentioned, the suspension train of the vehicle is an articulated double-wishbone train, comprising a suspension assembly 7; the latter comprises a vertical axis damper associated with a helical spring 71.

The base 70 of the damper rests on a stirrup 72 in the general shape of U inverted, inside which the wheel shaft 4 passes; the lower part of this stirrup serves as a clevis for a hinge 82 of one of the two arms 8 constituting the lower triangle.

The axis 820 of this articulation is disposed horizontally and longitudinally, considering the longitudinal axis of the vehicle.

The upper articulation triangle comprises, on the one hand, an assembly consisting of two links 50 of arcuate shape, integral with each other, articulated at their lower part to a fixed part V3 of the vehicle, around a axis 500 parallel to the aforementioned axis 820.

At their upper end these two rods 50 act as an articulation clevis for the other element 6 constituting the upper triangle; for this purpose, an end portion 61 of the element 6 positioned between the two links is supported by a hinge axis 501 parallel to the axis 500.

Element 6 has a generally triangular shape; one of its angles corresponds to the end portion 61; a second angle supports a tab - or tongue - 63 directed downwards; finally, the third angle supports a cup 62 which engages a ball 34 carried by the portion 32 of the hub carrier 3; the cooperation of the cup 62 and the ball 34 constitutes a multidirectional articulation pivot.

The first actuator 1, which consists of a cylinder, for example electric, comprises a body 10 and a rod 11. The body 10 is fixed, via a universal joint 13, to a fixed part V4 of the vehicle.

The end of its rod 11 carries a cup 12 which is engaged on a ball 33 also carried by the portion 32 of the hub carrier; the assembly constituted by the cup 12 and the ball 33 constitutes a multidirectional articulation pivot, similar to the pivot 34-62. The second actuator 2, which is also, advantageously, an electric jack, comprises a body 20 and a rod 21.

The body 20 is articulated by a sleeve 23 to the two links 50 between which it is positioned, so that it can pivot freely about an axis 502 parallel to axes 500 and 501 above.

The free end of the rod 21 of the actuator has the form of a yoke 22 which is articulated on the tongue 63 above by means of a hinge axis 64, axis 210 also parallel to the aforementioned axes.

All these axes are parallel to the longitudinal direction of the vehicle.

As already said, the lower suspension triangle is materialized by a pair of independent levers 8 and 9.

The lever 8 is articulated, on the body side, by an end portion 81 to a fixed portion V1 of the vehicle, about an axis 810 parallel to the aforementioned axis 820; its other end is articulated by a multidirectional pivot connection 36-80 to the lower part 30 of the hub carrier 3.

The arm 9, meanwhile, is articulated, on the body side, via an elastic hinge, its free end 91 to a fixed part V2 of the vehicle, about a vertical axis 910. Its opposite end is fixed via a connection to Multidirectional pivot 35-90 at the part 30 of the hub carrier 3.

In FIG. 2, the part 6 constituting the triangle-shaped upper articulation is represented as a solid plate 60.

In practice, as can be seen in particular in FIGS. 3 to 7, this element has the shape of an armature consisting of bent rods, and having a recessed portion in which the actuator 2 can be inserted, and more particularly the body 20 of this actuator.

This recess is covered with a hoop 65, which passes just above the body of the jack. This recessed configuration allows on the one hand to limit the mass of the element 6, and on the other hand to better integrate the body of the actuator inside the element.

The control circuits of each of the two actuators 1 and 2 make it possible to control, depending on the will of the driver and the steering strategies, at any moment, the degree of extension of their rod 11, respectively 21, out of their body 10 respectively 20. With reference to FIGS. 5A and 5B, it will be understood how to turn the wheel on one side or the other of the longitudinal direction of the vehicle, corresponding to the plane P, which has been mentioned above with reference to FIG. Figure 1.

In Figure 5, the actuator 1 is in a position such that its rod 11 is half retracted.

When it is desired to turn the wheels inward, it causes the retraction of the cylinder; this results in a displacement of the portion 32 of the hub carrier, which is close to the fixed part V4 of the vehicle; this displacement is reflected on the hub and the wheel, which takes the position in Figure 5A. Conversely, outward steering is similarly obtained when the jack is extended, as shown in FIG. 5B.

FIGS. 6 and 7 make it possible to understand how the actuator 2 is nested inside the armature 6, and how is deployed the assembly formed by the set of rods 50 and the armature 6.

In FIG. 6, the actuator is in a position of partial extension of its rod 21; in the position of Figure 7, this rod is in full extension.

As can be understood from the observation of FIGS. 8 and 9, the more or less retracted position of the rod of the actuator 21 inside the body 20 makes it possible to vary the camber angle of the wheel R with respect to ground S.

In these figures, the hub of the wheel bears the reference M; as already said, this hub is connected to the hub carrier 3.

When displacement of the rod 21 of the actuator 2 in the direction of its extension is caused, by means of the pivot joint 34-62, the displacement of the portion 32 of the hub carrier, due to the deformation the knee joint constituted by the two rods 50 and the armature 6.

As shown in Figure 8, the extension of the rod 21 causes a positive camber of the wheel, with an angle designated α; the retraction of the rod 21 causes the wheel to pivot in the direction of a negative camber, whose angle is designated β in FIG. 9.

The fact of providing an upper arm consisting of two elements articulated to each other 5, 6 provides an elongation of the arm which is greater than that of the actuator cylinder; thanks to this arrangement can therefore minimize the stroke of the cylinder, and therefore its length, to improve the compactness of the system. However, because of the length of the actuator cylinders 1 and 2, in this type of double wishbone train, the upper arm can not be very short because of the length of the cylinders.

The upper patella is therefore relatively externalized.

This is why the lower classic triangle has been replaced by a pair of arms that form a fictional pivot. This makes it possible to exteriorize the lower (fictional) ball joint so as to obtain a correct ground offset. The fictitious lower patella and the superior physical patella form a "semi-fictional" pivot. This type of train is therefore particularly suited to the steering and steering system of the proposed camber. The latter could also be integrated on a double triangle with a longitudinal motor.

In addition, on the proposed semi-imaginal pivot train, the high (real) and low (fictitious) joints are exteriorized so that the rocket offset is small, about 20 mm and negative, whereas it is high (about 60 mm) and positive on a standard train.

In the variant of FIGS. 10 and 11, the actuator 20 is interposed between the axis 500 of the link pair 50 and the tab 63 integral with the reinforcement 6.

The mode of operation of this variant is similar to that just described, the extension of the rod 21 of the actuator 2 having the effect of causing a positive camber of the wheel R (Figure 10), while on the contrary, the retraction of the rod 21 induces a negative camber (FIG. 11).

The embodiment illustrated in FIG. 12 differs from those previously described in that the first actuator, which acts on the steering, and which is referenced in FIG. 12, does not act at the upper end of the hub carrier 3. but at the lower end thereof, in the vicinity of the wheel axle.

This FIG. 12 represents the first actuator 1 'whose body 10' is articulated, for example via a cardan, to a fixed element of the vehicle, while the free end of its rod 11 'is fixed to the lower part 30 of the vehicle. hub carrier 3. The point of connection of the rod 11 'with the portion 30 of the hub carrier is disposed forward or rearward of the wheel axle, so that the deployment of the actuator therein, in the direction of the retraction or extension, causes the directional orientation of the wheel R.

Claims

1. Steering system for a motor vehicle, comprising a directional hub door (3) integral with the hub of a wheel (R) of the vehicle, and a first actuator (1; l ') controlled by a control circuit and control, and adapted to control the directional orientation of the wheel (R), characterized in that it comprises a second actuator (2) also controlled by a control and control circuit, and adapted to change the angle of camber of said wheel (R).

2. Steering system according to claim 1, characterized in that at least one of said actuators (1-1 '; 2) is an electric cylinder.

3. steering system according to claim 1 or 2, characterized in that, firstly, said hub carrier member (3) is a rod whose lower portion (30) is fixed to the hub, within the inner cavity of the wheel web (R), which is shaped so as to bypass the tire of the wheel inwards and upwards, so that its upper part (32) is above the wheel wheel (R), and that secondly, said second actuator (2) acts on this upper portion (32).

4. Steering system according to claim 3 for an articulated double-wishbone steering train, characterized in that the upper triangle comprises a deformable arm (5-6) in which said second actuator (2) is integrated, this arm ( 5-6) being articulated at one of its ends to a fixed part (V3) of the vehicle, and at its other end, via a pivot (34-62), to said upper part (32) of the hub carrier (3 ).

5. Steering system according to claim 4, characterized in that said deformable arm comprises a set of links (50) articulated to a fixed part (V3) of the vehicle, and a stirrup (6) itself articulated on this set of links (50), the body (20) of the second actuator (2) being articulated on the links (50), while its rod (21) is connected by a hinge (210) to said stirrup (6), and the latter being connected via said pivot (34-62) to the upper part (32) of the hub carrier (3).

6. Steering system according to claim 4 or 5, characterized in that the lower triangle is embodied by a pair of independent arms (8, 9) articulated at one end to a fixed part (VI, V2) of the vehicle, and at the other end, at the lower part (30) of the hub carrier (3).

7. Steering system according to claim 6, characterized in that one of said arms (8) supports, in its central zone, a damper (7) whose upper portion serves as a support for a fixed portion of the frame of the vehicle.

8. Steering system according to any one of claims 3 to 7, characterized in that said first actuator (1) also acts, via a pivot (12-33), on the upper part (32) of the hub carrier ( 3).

9. Steering system according to any one of claims 3 to 7, characterized in that said first actuator (Y) acts on the lower part (30) of the hub carrier (3), in the vicinity of the wheel axle .

10. Steering system according to any one of the preceding claims, characterized in that said first actuator (1) is an electric cylinder whose body (10) is fixed to a fixed part of the vehicle frame (V4) by the intermediate of a gimbal (13), and whose rod (11) is connected via a pivot (12-33) to the hub carrier (3).