Front structure of motor vehicle

Abstract

The invention relates to a front structure of a motor vehicle comprising: a body part having a front end and an engine compartment delimited by a bottom part and two side walls having upper support edges (22') respectively; two hub carriers (24') opposed to each other, connected respectively, on the one hand to said bottom part by two suspension arms, and on the other hand to said upper edges (22') by two damping devices (30'); two spring members connecting said two hub carriers (24') respectively to said body part; two transmission shafts (42') connected respectively to said two hub carriers (24').And, the two spring elements are connected respectively to the two hub carriers (24') via the two suspension arms, while the two damping devices (30') are mounted respectively opposite the front end of the two transmission shafts (42'). Figure to be published with the abbreviation: Fig. 2B.

Description

Title of the invention: Front structure of a motor vehicle

[0001] The present invention relates to a front structure of a motor vehicle aimed at substantially reducing the height of certain parts of the bodywork relative to the ground.

[0002] Known motor vehicle front structures comprise a body shell portion in which the engine compartment is arranged. This is delimited from the passenger compartment by a transversely extending apron and, opposite, by a front wall.

[0003] Also, the engine compartment has a bottom portion comprising a cradle and two side walls erected opposite each other with respect to the bottom portion. The side walls have upper edges which move away from each other to join the wings of the vehicle.

[0004] In addition, the structures comprise two hub carriers, also called stub axles, opposite one another, extending respectively in the extension of two transmission shafts to which they are connected. The two transmission shafts come from the engine group installed on the cradle. Thus, the hub carriers support the mechanical bearings and the wheel hub.

[0005] The two hub carriers are usually connected to the cradle by means of two suspension arms respectively, and also to the upper edges of the side walls by means of two damping devices.

[0006] The damping devices are then coupled to coil springs and they are then connected to the upper edges by means of suspension cups. The coil springs come to rest in the suspension cups.

[0007] In this way, the damping devices and the springs extend vertically from the transmission shafts. They have a minimum length which requires the provision of two edges of a sufficiently high height relative to the cradle and the transmission shafts to be able to install them.

[0008] Also, the height of the side walls delimiting the engine compartment, and consequently, the height of the front structure of the vehicle relative to the ground is conditioned by the vehicle's damping devices.

[0009] A problem which arises and which the present invention aims to solve is to provide a front structure of a motor vehicle which can be lowered relative to the ground compared to the structures according to the prior art.

[0010] For this purpose, and according to a first object, there is proposed a front structure of a motor vehicle comprising: a body shell part having an end front and an engine compartment delimited by a bottom part and two facing side walls erected relative to said bottom part, said two side walls respectively having upper support edges extending opposite one another; two hub carriers opposite one another, connected respectively, on the one hand to said bottom part by two suspension arms, and on the other hand to said upper edges by two damping devices; two spring members respectively connecting said two hub carriers to said body part; two transmission shafts respectively connected to said two hub carriers and extending towards one another.

[0011] Also, said two spring members are connected respectively to said two hub carriers via said two suspension arms, while said two damping devices are mounted respectively opposite said front end relative to said two transmission shafts.

[0012] Thus, a characteristic of the invention lies, first of all, in the implementation of the spring members at the level of the suspension arms, and no longer above the hub carriers. Then, it lies in the implementation of the damping devices behind the transmission shafts, so as to be able to lower them. Therefore, it is possible to design the side walls of the engine compartment, and therefore the edges, lower. Consequently, it is possible to design a front structure of a motor vehicle lower in relation to the ground. In other words, the height of the front part of the vehicle alone, between the hood and the underbody, can be reduced compared to vehicles according to the prior art.

[0013] This has advantages, particularly in the event of a “pedestrian impact”. In addition, such a configuration allows greater freedom in the design of the front structures of motor vehicles.

[0014] According to a particularly advantageous implementation characteristic of the invention, said two spring members are integral with said bottom part. The bottom part advantageously comprises a cradle, which supports the motorization. Thus, the spring members are advantageously integral with the cradle of the motor vehicle.

[0015] Furthermore, said two suspension arms are integral with said bottom part. The two suspension arms are thus mounted respectively, articulated on the bottom part, and more precisely on the cradle of the motor vehicle.

[0016] In addition, each damping device has a middle portion connected to the hub carrier. The damping devices extend longitudinally because usually, it comprises a cylinder filled with a viscous fluid and in which is slidably mounted a rod provided with a piston dividing the cylinder into two chambers. For example, the piston has a passage orifice or a circuit of fluid flow from one chamber to the other. Thus, by connecting not the end of the damping device to the hub carrier, but its middle part, its end is necessarily lowered relative to the hub carrier. And consequently, as will be explained in the rest of the description, lower side walls can be designed.

[0017] Also, each damping device has a lower end opposite an upper end, and said upper end is oriented towards said front end, while said lower end is oriented opposite said front end. Thus, the damping device is substantially inclined, so that its upper end can remain substantially in line with the transmission shaft, while its lower end is moved away from it towards the rear so as to be able to extend normally there.

[0018] Furthermore, said two damping devices extend in the same vertical plane as will be explained in more detail in the remainder of the description.

[0019] Furthermore, according to a first embodiment, said two spring members are respectively connected to said suspension arms to operate in torsion. In other words, the spring members comprise a steel rod secured to the cradle and extending parallel to the suspension arms, terminating in a return connected to said suspension arm. The return is, for example, connected to said suspension arm by a pivot or ball joint. In this way, the pivoting of the suspension arm causes the pivoting of the return and consequently, the torsion of the steel rod. The torsional deformation of the rod then causes an elastic return, thus forming a spring.

[0020] According to a second embodiment, said two spring members are respectively connected to said suspension arms to operate in flexion. Here it is the elastic flexion of a steel blade which operates to form a spring.

[0021] According to a second object, a motor vehicle is proposed comprising a front structure as described above.

[0022] Other features and advantages of the invention will emerge from reading the description given below of a particular embodiment of the invention, given for informational purposes but not as a limitation, with reference to the appended drawings in which:

[0023] [Fig.lA] is a partial schematic cross-sectional view of a front structure of a motor vehicle according to the prior art;

[0024] [Fig.lB] is a partial schematic view in axial section of the object of [Fig.lA];

[0025] [Fig.2A] is a partial schematic cross-sectional view of a structure front of a motor vehicle according to the invention; and,

[0026] [Fig.2B] is a partial schematic view in axial section of the object of [Fig.2A]

[0027] [Fig.1A] partially shows, in cross section, a front structure of motor vehicle, according to the prior art. More specifically, [Fig.lA] shows a body shell part including a “pseudo MacPherson” type suspension, making it possible to connect the unsprung elements of the motor vehicle to the suspended elements.

[0028] The structure is inscribed in an orthogonal reference frame X, Y, Z, in which the X axis extends in a front-rear longitudinal direction of the motor vehicle, oriented towards the rear; the Y axis extends in a transverse direction of the vehicle, oriented from left to right when in a rolling situation; and the Z axis extends in a vertical direction, oriented away from the ground.

[0029] Thus, [Fig.lA] shows the right front wheel 10 of a motor vehicle resting on the ground, a horizontal surface wall 12. Also, the engine compartment 14 appears, delimited laterally by a right side wall 16 and by a bottom part 18 comprising a cradle 20.

[0030] The right side wall 16 has a curved upper edge 22 which extends substantially horizontally opposite the engine compartment 14. The upper edge 22 joins the upper edge of the wing, not shown, of the vehicle.

[0031] Also, the wheel 10 is integral with a hub carrier 24, also called a stub axle. The latter is kept in balance, on the one hand by a suspension arm 26, mounted articulated on the cradle 20 and on the hub carrier 24, and on the other hand by a strut 28, extending vertically along the z component, from the hub carrier 24 to the upper edge 22 of the right side wall 16.

[0032] The strut 28 comprises a damping device 30 comprising, on the one hand, a cylinder 32 filled with a fluid, and on the other hand, a rod 34 provided with an openwork piston slidably mounted inside the cylinder 32. The cylinder 32 has a lower end 33 connected to the hub carrier 24, while the rod 34 has an upper end 35 bearing in the bottom of an upper cup 36, itself bearing against the upper edge 22.

[0033] In addition, the strut 28 comprises a lower cup 38 secured to the cylinder 32, and a helical spring 40 surrounding the rod 34 and coming into axial engagement between the two cups 36, 38.

[0034] Furthermore, the hub carrier 24 is integral with a straight transmission shaft 42. The latter extends transversely towards the center of the engine compartment 14 to join the differential housing, not shown.

[0035] [Fig.lB] shows in parallel elements shown in [Fig.lA], seen from inside the engine compartment 14. Thus, it is understood that the right engine shaft 42 extends precisely in line with the right strut 28 and that the cylinder 32 of the damping device 30 extends in the vicinity of the transmission shaft 42.

[0036] All the elements described above relate only to the right part of the front structure of the motor vehicle. However, they are reproduced identically in the left part in a symmetrical manner with respect to an axial vertical median plane parallel to the X,Z plane.

[0037] In this way, it is understood from these [Fig.lA] and [Fig.lB], that it is impossible to reduce the height of the side wall 16 and consequently, to significantly lower the height of its upper edge 22 relative to the ground 12, taking into account the position of the strut 28.

[0038] And the object of the invention, which will be explained below with reference to [Fig.2A] and [Fig.2B], is precisely aimed at a new architecture making it possible to reduce the height of the side wall 16 while retaining the characteristics of the suspension.

[0039] Also, elements identical or similar to those illustrated in [Fig.lA] and [Fig.lB], and having the same function, will bear the same reference with a prime sign: “'”.

[0040] Thus, [Fig.2A] shows a right front wheel 10' of a motor vehicle resting on a horizontal surface wall 12'. Also, the engine compartment 14' appears, delimited laterally by a right side wall 16' and by a bottom part 18' comprising a cradle 20'.

[0041] Compared to the embodiment according to the prior art illustrated in [Fig.lA] and [Fig.lB], it has been imagined according to the invention, first of all to decouple the functions of shock absorber and elastic deformation. In other words, the damping device 30' is dissociated from the spring-forming element 40'.

[0042] Thus, first of all, a torsion bar 40' is installed on the bottom wall 18' and the cradle 20'. The torsion bar 40' has one end engaged in the cradle 18' and a free part 44' which extends substantially parallel to the suspension arm 26'. And the torsion bar 40' has a return end 46' secured to the suspension arm 26'.

[0043] Advantageously, the return end 46' is pivotally mounted on the suspension arm 26'. Thus, the spring function between the body shell and the hub carrier 24' is no longer provided by a helical spring, but by the torsion bar 40' via the suspension arm 26'. The torsion bar 40' deforms elastically by rotation about its own axis.

[0044] Furthermore, the damping device 30', retained in its shape, is arranged differently. Thus, as illustrated, seen from the outside in [Fig.2B], the cylinder 32' of the damping device 30' has a lower central zone 48' equipped with a recessed ear 50' and held by two screws to the hub carrier 24', at the rear of the transmission shaft 42'.

[0045] Thus, the lower end 33' of the cylinder 32' extends to the rear of the shaft of transmission 42', while the upper end 35' extends substantially to the right of the transmission shaft 42'.

[0046] Thus, the damping device 30' is inclined and lowered relative to the damping device 30 shown in [Fig.lA] and [Fig.lB] in accordance with the prior art. As a result, the height of the side wall 16' can be reduced, and its curved edge 22' can extend to a level close to the level of the bottom portion 18', relative to the relative position of the upper edge 22 and the bottom portion 18 according to the prior art.

[0047] Thus, the upper end 35' of the rod 34' comes to bear precisely against the upper edge 22, by means of a cup 36'.

[0048] In this way, the damping device 30' plays its damping role on one side, while the torsion bar 40' plays its spring role on the other side, indirectly via the suspension arm 26'.

[0049] The left part of the front structure is arranged in the same way and is symmetrical with respect to the vertical median plane.

[0050] The invention also relates to a motor vehicle having the front structure as described above.

Claims

Claims

1. Front structure of a motor vehicle comprising: - a body part having a front end and an engine compartment (14') delimited by a bottom part (18') and two facing side walls (16') erected relative to said bottom part, said two side walls (16') respectively having upper bearing edges (22') extending opposite one another - two hub carriers (24') opposite one another, connected respectively, on the one hand to said bottom part (18') by two suspension arms (26'), and on the other hand to said upper edges (22') by two damping devices (30'); - two spring members (40') respectively connecting said two hub carriers (24') to said body part; - two transmission shafts (42') connected respectively to said two hub carriers (24') and extending towards each other;characterized in that said two spring members (40') are connected respectively to said two hub carriers (24') via said two suspension arms (26'), while said two damping devices (30') are mounted respectively opposite said front end relative to said two transmission shafts (42').;

2. Front structure according to claim 1, characterized in that said two spring members (40') are integral with said bottom part (18').

3. Front structure according to claim 1 or 2, characterized in that said two suspension arms (26') are integral with said bottom part (18').

4. Front structure according to any one of claims 1 to 3, characterized in that said bottom part (18') comprises a cradle (20').

5. Front structure according to any one of claims 1 to 4, characterized in that each damping device (30') has a middle part (48') connected to the hub carrier (24').

6. Front structure according to any one of claims 1 to 5, characterized in that each damping device (30') has a lower end (33') opposite an upper end (35'), and in that said upper end (35') is oriented towards said front end, while said lower end (33') is oriented opposite the said end.

7. Front structure according to any one of claims 1 to 5, characterized in that said two damping devices (30') extend in the same vertical plane.

8. Front structure according to any one of claims 1 to 7, characterized in that said two spring members (40') are respectively connected to said suspension arms (26') to operate in torsion.

9. Front structure according to any one of claims 1 to 7, characterized in that said two spring members are respectively connected to said suspension arms to operate in flexion.

10. A motor vehicle comprising a front structure according to any one of claims 1 to 9.

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