FR3134783A1 - REAR CRADLE WITH REINFORCED RESISTANCE, FOR A LAND VEHICLE - Google Patents

Abstract

A rear cradle (BR) equips a land vehicle (VT) comprising a rear axle with side arms and a rear driving machine (MM) having a transmission shaft (AT) coupled to said rear axle. This rear cradle (BR) comprises two lateral parts (PLB) to which the rear driving machine (MM) and side arms are secured and each comprising a passage (PA) for the transmission shaft (AT). Each lateral part (PLB) has, at least in a lower sub-part (SPI) delimiting a lower portion of the passage (PA), a box structure capable of absorbing forces below a threshold and resulting from a shock suffered by the rear by the land vehicle (VT). Figure to be published with the abstract: Fig. 3

Description

REAR CRADLE WITH REINFORCED RESISTANCE, FOR A LAND VEHICLE Technical field of the invention

The invention concerns land vehicles, and more specifically the rear cradles which are part of such vehicles (possibly within platforms).

State of the art

Certain land vehicles, generally of the automobile type, comprise a structure (or possibly a platform) comprising a rear floor to which is secured a rear cradle comprising two lateral parts (right and left) to which are respectively coupled two lateral rear axle arms (right and left) and a rear-wheel drive machine forming part of a powertrain (or GMP). Generally, each side part of this rear cradle comprises a front part and a rear part connected by at least one upper tube and a lower tube between which is defined a passage adapted to the crossing and the movement of the transmission shaft of the machine rear drive.

In what precedes and follows the notion of “front” is defined in relation to the front end of the vehicle, and the notion of “rear” is defined in relation to the rear end of the vehicle (opposite to the front end). Therefore, the front part of an element is (intended to be) oriented towards the front end of the vehicle, while the rear part of that element is (intended to be) oriented towards the rear end of the vehicle.

When the vehicle suffers an impact from behind at high speed with an object having a relatively small vertical extension, the rear cradle offers, with the equipment that it supports or which is coupled to it, an additional contact surface which comes added to the “main” contact surface offered by the rear end of the vehicle structure. Due to the weight and bulk of the rear cradle, the rear axle side arms and the rear driving machine, the impact of the object with the rear cradle can be violent (the force absorbed can typically be between 30 kN (or 3 tonnes) and 50 kN (or 5 tonnes)). Consequently, this can cause a downward bending of the rear cradle in its front part, because the tubes of the lateral parts (and in particular the lower tube) cannot withstand this force, and this can result in tearing of the points of support. fixing the rear axle and the blocks of the driving machine.

It should be noted that the situation can be even more problematic when the vehicle includes, slightly in front of the rear subframe, a main battery (providing electrical energy to the rear driving machine when it is electric), because the front part of the subframe is bent rear can damage the main battery which can be dangerous in terms of electrical safety and/or pollution.

In addition, the electrical power harness of the rear driving machine may find itself damaged, or even exposed, and in contact with the structure of the vehicle, which may cause a fire and/or electrocution of a passenger or a passenger. person intervening on the damaged vehicle.

The invention therefore aims in particular to improve the situation.

Presentation of the invention

It proposes in particular for this purpose a rear cradle, on the one hand, capable of being secured to an underside of a floor of a land vehicle comprising a rear axle with lateral arms and a rear driving machine having a coupled transmission shaft to this rear axle, and, on the other hand, comprising two lateral parts to which are intended to be secured respectively this rear driving machine and these lateral arms, and each comprising a passage adapted to the crossing and the movement of the transmission shaft .

This rear cradle is characterized by the fact that each lateral part has, at least in a lower sub-part delimiting a lower portion of the passage, a box structure capable of absorbing forces lower than a chosen threshold and resulting from an impact suffered. from the rear by the land vehicle in a direction having a component parallel to a longitudinal direction.

Thanks to the invention, in the event of an impact from the rear the rear cradle can now, due to its box structure at least in its lower sub-part, absorb forces lower than the chosen threshold, and therefore as long as the forces absorbed remain below this threshold there is no longer any risk of bending of the rear cradle.

The rear cradle according to the invention may include other characteristics which can be taken separately or in combination, and in particular:

- in a first embodiment, each side part may comprise a main part delimiting a portion of the passage which is complementary to its lower portion, and on which the lower sub-part is attached;

- in a first embodiment, each lower sub-part may comprise an upper part having a section in the general shape of an inverted U and a lower part fixedly secured to a lower end of this upper part, the upper part and lower part defining the box structure;

- in the presence of the last option, each lower sub-part can have a height in a vertical direction of the land vehicle which is between 25 mm and 45 mm, and a width in a transverse direction of the land vehicle which is between 80 mm and 100mm;

- also in the presence of the last option, each lower sub-part can be made of steel from at least one sheet having a thickness of between 1.5 mm and 2.5 mm. Alternatively, each lower sub-part can be made of aluminum from at least one sheet having a thickness of between 2.5 mm and 4 mm.

- in a second embodiment, each side part may comprise first and second main flanges which are fixedly secured to each other and shaped so as to together define an overall box structure including the lower sub-part and delimiting at least partially the passage;

- in this second embodiment, the first and second main flanges of each side part can define an opening at the interface with an internal part of the passage, and each side part can comprise at least one auxiliary flange fixedly secured to the first and second main flanges and shaped so as to sealingly mask this opening and to participate in the delimitation of the passage;

- also in this second embodiment, the first and second main flanges of each side part can each be made of steel from at least one sheet having a thickness of between 1.5 mm and 2.5 mm, or else made of aluminum from at least one sheet having a thickness of between 2 mm and 4 mm.

The invention also proposes a land vehicle, possibly of the automobile type, and comprising:

- a floor,

- a rear axle with lateral arms,

- a rear driving machine having a transmission shaft coupled to this rear axle, and

- a rear cradle of the type presented above and to which this rear driving machine and these lateral arms are secured.

For example, the rear driving machine may be an electric machine supplied with electrical energy by a main battery.

Brief description of the figures

Other characteristics and advantages of the invention will appear on examination of the detailed description below, and the appended drawings (obtained in CAD/CAD (“Computer Aided Design/Computer Aided Drawing”)), on which :

schematically illustrates, in a perspective view from below and partially in section in a longitudinal and vertical plane, a right rear part of an example of a motor vehicle comprising a right part of a first example of embodiment of a rear cradle according to the 'invention,

schematically illustrates, in a sectional view in a transverse and vertical plane, the right part of the rear cradle of the ,

schematically illustrates, in a perspective view from below and partially in section in a longitudinal and vertical plane, a right rear part of an example of a motor vehicle comprising a right part of a second example of embodiment of a rear cradle according to the invention, and

schematically illustrates, in a sectional view in a transverse and vertical plane, the right part of the rear cradle of the .

Detailed description of the invention

The invention aims in particular to propose a rear cradle BR suitable for equipping a land vehicle VT and having reinforced (or increased) resistance so as to increase its capacity to absorb shocks from the rear, including at high speed.

In what follows, we consider, by way of non-limiting example, that the rear cradle BR is intended to be part of a land vehicle VT of automobile type, such as for example a car. But the invention is not limited to this type of land vehicle. It concerns in fact any land vehicle comprising a rear floor to which is secured a rear cradle (to which are coupled a rear driving machine forming part of a GMP and two lateral arms of a rear axle), and capable of being subjected to shocks by the 'back.

Furthermore, we consider, by way of non-limiting example, that the rear driving machine is an electric machine (or motor) responsible for rotating the wheels of at least one rear axle thanks to the electrical energy supplied by a main (or traction) battery installed in its base (here under the floor). Consequently, the GMP is of the all-electric or hybrid type (thermal and electric).

In Figures 1 to 4, the direction X, and the direction Z is the vertical direction of the vehicle VT, which is perpendicular to the longitudinal X and transverse Y directions.

We have schematically illustrated in Figures 1 and 2 the right rear parts of examples of land vehicle VT, which respectively comprise parts (right) of first and second examples of production of a rear cradle BR according to the invention.

As partially illustrated, the vehicle VT comprises in its rear part a PLV floor comprising a lower face FI to which is fixedly secured a rear cradle BR to which is in particular coupled a rear driving machine MM (here an electric motor) of the GMP, loaded ) to rotate at least the rear wheels of the rear axle. For this purpose, the rear driving machine MM has an AT transmission shaft which is coupled to the rear axle. This rear driving machine MM produces torque (for rotating the transmission shaft AT) from the electrical energy which is stored in a main (or traction) battery installed in its base (for example under the POS floor).

Note that the lower face FI of the PLV floor is oriented downwards (or the ground) and is opposite to an upper face which is oriented upwards.

The rear wheels (right and left) are respectively coupled to two lateral arms BL (right and left) of the rear axle, which are also coupled to lateral parts PLB (right and left) of the rear cradle BR. These lateral parts PLB are for example coupled together via a front cross member TV and a rear cross member TR which extend in the transverse direction Y.

As illustrated in Figures 1 to 4, each of the two lateral parts PLB of the rear cradle BR includes a passage PA which is adapted to the crossing and the travel of the transmission shaft AT. In addition, each lateral part PLB has, at least in a lower sub-part SPI delimiting a lower portion of the passage PA, a box structure which is capable of absorbing forces lower than a chosen threshold sc and which result from an impact suffered from the rear by the vehicle VT in a direction having a component parallel to the longitudinal direction X of the vehicle VT.

Thus, when the vehicle VT suffers an impact from behind (possibly at high speed) with an object having a relatively small vertical extension, the rear cradle BR can now, due to its box structure at least in its sub-frame, lower part SPI, absorb the forces resulting from this shock, as long as these forces are lower than the chosen threshold sc. Consequently, as long as the forces remain below sc, there is no longer any risk of bending of the rear cradle BR, and therefore of tearing of the rear axle attachment points and the chocks of the rear driving machine MM. In addition, in the presence of a main battery located slightly in front of the rear cradle BR, there is no longer a risk that the latter (BR) will damage this main battery as long as the forces remain below sc. In addition, the rear cradle BR remaining (almost) integrated as long as the forces remain less than sc, there is no longer any risk that the electrical supply harness of the rear driving machine MM is damaged, or even stripped, which helps prevent a fire and/or electrocution of a passenger or a person working on the damaged VT vehicle.

The invention therefore makes it possible to reinforce the passive safety offered by the VT vehicle.

For example, the box structure of the rear cradle BR can be arranged and dimensioned so that it can withstand forces lower than a chosen threshold sc of between 30 kN (or 3 tonnes)) and 70 kN (or 7 tonnes)) , and more preferably between 50 kN (or 3 tonnes) and 70 kN (or 7 tonnes)).

At least two embodiments can be envisaged for the BR rear cradle.

In a first embodiment illustrated in Figures 1 and 2, each lateral part PLB of the rear cradle BR comprises a main part PP and the lower sub-part SPI. The main part PP delimits a portion of the passage PA which is complementary to its lower portion (delimited by the lower sub-part SPI), and the latter (SPI) is attached to the main part PP and has the box structure which allows the rear cradle BR to absorb forces lower than the chosen threshold sc. It will be understood that in this first embodiment the main part PP does not necessarily have a box structure, although this is possible in at least one of its sub-parts (as for example in its sub-part upper portion which delimits the upper portion of the PA passage).

Preferably, each lower SPI sub-part is fixedly attached to the associated main PP part by welding. But screwing can also be considered.

In a variant embodiment not illustrated, each lateral part PL could be in one piece, and in this case its lower sub-part SPI and its main part PP extend mutually, with of course the condition that at least the lower sub-part SPI has a box structure.

As illustrated without limitation in Figures 1 and 2, the lower sub-part SPI may comprise an upper part PSS and a lower part PIS. As illustrated without limitation on the , the upper part PSS may have a section in the general shape of an inverted U, and in this case comprises an opening oriented downwards. The lower part PIS is fixedly attached to the lower end of the upper part PSS, which closes the opening of the upper part PSS. Thus, the upper part PSS and lower part PIS together define a box structure capable of absorbing (or supporting) very significant forces (less than sc) in the event of an impact suffered from the rear by the vehicle VT following a direction having a component parallel to the longitudinal direction

For example, the lower sub-part SPI can have a height in the vertical direction Z which is between 25 mm and 45 mm. As an illustrative example, this height can be equal to 35 mm.

Also for example, the lower sub-part SPI can have a width in the transverse direction Y which is between 80 mm and 100 mm. As an illustrative example, this width can be equal to 90 mm.

Also for example, the lower SPI sub-part can be made of steel from at least one sheet. Thus, this steel can be of type S420MC. In this case, this (each) steel sheet can, for example, have a thickness which is between 1.5 mm and 2.5 mm. As an illustrative example, this thickness can be equal to 2 mm. It will be noted that when the lower sub-part SPI comprises an upper part PSS and a lower part PIS, the steel sheets in which they are made may possibly have different thicknesses.

Alternatively, the lower SPI sub-part can be made of aluminum from at least one sheet. Thus, this aluminum can be of type T6-6061. In this case, this (each) aluminum sheet can, for example, have a thickness which is between 2.5 mm and 4 mm. It will be noted that when the lower sub-part SPI comprises an upper part PSS and a lower part PIS, the aluminum sheets in which they are made may possibly have different thicknesses. As an illustrative example, the thickness of the upper part PSS can be equal to 3.5 mm and the thickness of the lower part PIS can be equal to 3 mm.

In another variant, the lower SPI sub-part (with box structure) could be made from a very resistant composite material.

In a second embodiment illustrated in Figures 3 and 4, each lateral part PLB of the rear cradle BR comprises first FP1 and second FP2 main flanges which are fixedly joined to each other. Moreover, and as it appears better on the , these first FP1 and second FP2 main flanges are shaped so as to together define an overall box structure which includes the lower sub-part SPI and at least partially delimits the passage PA. This second embodiment advantageously allows the rear cradle BR to withstand forces lower than a chosen threshold sc which is possibly higher than in the first embodiment, or to withstand forces similar to those of the first embodiment but with sub-parts of its lateral parts PLB having smaller dimensions than those of the lower sub-part SPI of the first embodiment.

Preferably, the first FP1 and second FP2 main flanges of each side part PLB are fixedly joined together (possibly with an edge overlap) by welding.

For example, and as illustrated without limitation in Figures 3 and 4, the first FP1 and second FP2 main flanges of each lateral part PLB can define an opening at the interface with the internal part of the passage PA. In this case, each lateral part PLB can comprise at least one auxiliary flange FA fixedly secured to the first FP1 and second FP2 main flanges and shaped so as to sealingly mask this opening and to participate in the (internal) delimitation of the passage PA. This arrangement makes it possible to simplify the production of each of the first FP1 and second FP2 main flanges, and to prevent elements (liquids or small bodies) from penetrating and accumulating inside the PLB lateral parts. In addition, each auxiliary flange FA can also possibly contribute to the solidity and resistance of its lateral part PLB.

Preferably, each auxiliary flange FA is fixedly secured by welding to the first FP1 and second FP2 associated main flanges.

For example, each of the first FP1 and second FP2 main flanges can be made of steel from a sheet. Thus, this steel can be of type S420MC. In this case, this steel sheet can, for example, have a thickness which is between 1.5 mm and 2.5 mm. As an illustrative example, this thickness can be equal to 2 mm.

Alternatively, each of the first FP1 and second FP2 main flanges can be made of aluminum from a sheet. Thus, this aluminum can be of type T6-6061. In this case, this aluminum sheet can, for example, have a thickness which is between 2 mm and 4 mm. As an illustrative example, this thickness can be equal to 3.5 mm.

Also for example, each possible FA auxiliary flange can be made of steel from a sheet. Thus, this steel can be of type S420MC. In this case, this steel sheet can, for example, have a thickness which is between 1 mm and 2 mm. As an illustrative example, this thickness can be equal to 1.5 mm.

Alternatively, each possible auxiliary flange FA can be made of aluminum from a sheet. Thus, this aluminum can be of type T6-6061. In this case, this aluminum sheet can, for example, have a thickness which is between 1.5 mm and 3 mm. As an illustrative example, this thickness can be equal to 2.5 mm.

Claims (10)

Rear cradle (BR) capable of being secured to a lower face (FI) of a floor (PLV) of a land vehicle (VT) comprising a rear axle with lateral arms (BL) and a rear driving machine (MM) having a transmission shaft (AT) coupled to said rear axle, said rear cradle (BR) comprising two lateral parts (PLB) to which are intended to be secured respectively said rear driving machine (MM) and said lateral arms (BL) and each comprising a passage (PA) adapted to the crossing and the movement of said transmission shaft (AT), characterized in that each lateral part (PLB) has, at least in a lower sub-part (SPI) delimiting a lower portion of said passage (PA ), a box structure capable of absorbing forces below a chosen threshold and resulting from an impact suffered from the rear by said land vehicle (VT) in a direction having a component parallel to a longitudinal direction. Rear cradle according to claim 1, characterized in that each lateral part (PLB) comprises a main part (PP) delimiting a portion of said passage (PA) which is complementary to its lower portion, and on which said lower sub-part is attached (SPI). Rear cradle according to claim 2, characterized in that said lower sub-part (SPI) comprises an upper part (PSS) having a section in the general shape of an inverted U and a lower part (PIS) fixedly secured to a lower end of said upper piece (PSS), said upper piece (PSS) and lower piece (PIS) defining said box structure. Rear cradle according to claim 3, characterized in that said lower sub-part (SPI) has a height in a vertical direction of said land vehicle (VT) of between 25 mm and 45 mm, and a width in a transverse direction of said land vehicle (VT) between 80 mm and 100 mm. Rear cradle according to claim 3 or 4, characterized in that said lower sub-part (SPI) is made of steel from at least one sheet having a thickness of between 1.5 mm and 2.5 mm. Rear cradle according to claim 3 or 4, characterized in that said lower sub-part (SPI) is made of aluminum from at least one sheet having a thickness of between 2.5 mm and 4 mm. Rear cradle according to claim 1, characterized in that each lateral part (PLB) comprises first (FP1) and second (FP2) main flanges fixedly secured to one another and shaped so as to together define a box structure global including said lower sub-part (SPI) and at least partially delimiting said passage (PA). Rear cradle according to claim 7, characterized in that said first (FP1) and second (FP2) main flanges of each lateral part (PLB) define an opening at the interface with an internal part of said passage (PA), and in this that each side part (PLB) comprises at least one auxiliary flange (FA) fixedly secured to said first (FP1) and second (FP2) main flanges and shaped so as to sealingly mask said opening and to participate in the delimitation of said passage ( PA). Rear cradle according to claim 7 or 8, characterized in that said first (FP1) and second (FP2) main flanges are each made of steel from at least one sheet having a thickness of between 1.5 mm and 2, 5 mm, or in aluminum from at least one sheet having a thickness of between 2 mm and 4 mm. Land vehicle (VT) comprising a floor (PLV), a rear axle with lateral arms (BL) and a rear driving machine (MM) having a transmission shaft (AT) coupled to said rear axle, characterized in that it comprises in in addition to a rear cradle (BR) according to one of the preceding claims, to which said rear driving machine (MM) and said lateral arms (BL) are secured.