Rear axle module for connection to a rear structure of a motor vehicle body

Abstract

Rear axle module (1) for connection to a rear vehicle structure (2) of a motor vehicle body, with a lower frame structure (3) and respective side structures (8, 9) projecting upwards from the frame structure (3) in the vertical direction of the vehicle, to which respective chassis components of a rear axle can be fastened, with a rear transverse structure (10) at the rear end of the rear axle module (1), via which the side structures (8, 9) are connected to one another in a rear region, and with a front transverse element (23) via which the side structures (8, 9) are connected to one another in a front region, characterized in that an internal combustion engine (22) is arranged on the frame structure (3) between the side structures (8, 9), the rear transverse structure (10) and the transverse element (23).

Description

[0001] The invention relates to a rear axle module for connection to a rear vehicle structure of a motor vehicle body according to the preamble of patent claim 1.

[0002] Such a rear axle module is already known, for example, from the BMW i8 (model series I12 and I15). This module features a rear axle module that is connected from below to a rear structure of the vehicle body made of carbon fiber reinforced plastic. The rear axle module assumes functions and components typically associated with the rear structure of the vehicle body.

[0003] The rear axle module comprises a lower frame structure arranged on a lower level, to which respective side structures are attached, projecting from the frame structure in the vertical direction of the vehicle. For example, respective chassis components such as control arms or the like of the respective rear axle can be attached or supported on these side structures. Furthermore, the rear axle module comprises a rear transverse structure at its rear end, via which the side structures are connected to one another in a respective rear region.

[0004] The frame structure, the side structures, and the rear cross structure are formed from profile and sheet metal shell components. The rear axle module, for example, assumes the function of the respective rear longitudinal members of the rear structure of the vehicle body, via which a rear bumper is supported on the cross member.

[0005] DE 10 2004 062 932 B4 discloses a rear floor structure of a motor vehicle. A vehicle frame is known from DE 10 2019 127 876 A1, which forms the generic type. A body structure for a motor vehicle is known from DE 10 2006 012 629 A1. Furthermore, DE 103 02 756 B4 discloses a supporting structure for a motor vehicle body. Furthermore, a body is known from DE 102 27 635 A1. Furthermore, a shock absorption structure of a motor vehicle is known from DE 11 2016 004 865 T5. DE 10 2020 128 193 A1 discloses a vehicle underbody structure. A vehicle body is known from DE 100 23 112 A1. In addition, AT 414 118 B discloses a module of a safety cell of a means of transport.

[0006] The object of the present invention is to provide a rear axle module of the type mentioned above, the static and dynamic rigidity of which is improved and which, moreover, offers improved crash performance and other functional advantages.

[0007] This object is achieved according to the invention by a rear axle module having the features of patent claim 1. Advantageous embodiments with expedient further developments of the invention are the subject of the dependent claims.

[0008] The rear axle module according to the invention for connection to a rear vehicle structure of a motor vehicle body comprises a lower frame structure and respective side structures on the outer sides of the rear axle module, which protrude upwards from the frame structure in the vertical direction of the vehicle. Respective chassis components of a rear axle, such as control arms or the like, can be supported and fastened to these side structures. Furthermore, the rear axle module comprises a rear transverse structure at the rear end of the rear axle module, via which the side structures are connected to one another in their respective rear regions.

[0009] According to the invention, a front cross member is provided via which the side structures are connected to one another in one or their front region. Such a front cross member enables improved static and dynamic rigidity of the rear axle module, particularly when, for example, a higher engine power and greater drive weight result in a higher load on the rear axle module and thus, for example, increased acoustic requirements. The cross member creates a transverse shear field, which has a positive effect on the rigidity of the entire vehicle. A further advantage is that the front cross member also improves the vehicle's accident safety, particularly in the event of a rear-end collision.For example, it is particularly important to effectively prevent excessive forward displacement of components arranged behind the cross member, in particular an engine, in a forward direction, for example in the direction of a tank or energy storage device arranged in front of the front cross member.

[0010] An internal combustion engine is mounted on the frame structure between the side structures, the rear cross member, and the cross member. This engine can be supported particularly advantageously by the rear axle module, thus positioning the engine near the center of gravity.

[0011] A further advantage is that the front cross member can also provide other separation and subdivision functions. For example, if the engine is located behind the front cross member, it is particularly advantageous that the front cross member can provide thermal insulation to the front.

[0012] Another advantage is that the front cross member can be used to mount and, in particular, pre-assemble vehicle components, especially the drivetrain. For example, it is conceivable to arrange and pre-assemble cables, control units, or the like on the cross member to simplify the production of the rear axle module and the vehicle as a whole.

[0013] In a further embodiment of the invention, it has proven advantageous if the front cross member is also connected to a cross member of the lower frame structure. This particularly advantageously results in the cross member being connected essentially at three connection points, namely two at the top and one at the bottom. This allows for the creation of a particularly favorable transverse shear field.

[0014] Furthermore, it has proven advantageous if the front cross member is detachably connected to the side structures and / or the cross member of the lower frame structure. This allows for a favorable installation of an engine or other component located behind the front cross member, especially if the component is particularly space-consuming.

[0015] Furthermore, it has proven advantageous if the front cross member is essentially V-shaped and connected at its upper end regions to the side structure assigned to the side, and at a central lower region to the cross member of the lower frame structure. This results in a particularly advantageous connection of the front cross member at three connection points: two at the top on the vehicle's outer sides and one at the bottom in the central region of the frame structure.

[0016] In a further embodiment of the invention, a tank for the combustion engine is arranged in front of the front cross member. By arranging the front cross member between the engine or other component and the tank, the front cross member ensures in a particularly advantageous manner that the tank cannot be damaged even in the event of a rear-end collision.

[0017] Furthermore, it has proven advantageous to arrange an electrical energy storage unit for the combustion engine in front of the front cross member. This also offers the advantage that the front cross member provides particularly effective protection for the electrical energy storage unit against damage caused by an engine or other component located behind the front cross member, particularly in the event of a rear-end collision.

[0018] Finally, it has proven advantageous if at least one component, particularly the vehicle's drive system, is pre-assembled on the front cross member. This further simplifies the production of the rear axle module and the vehicle as a whole.

[0019] The invention will now be explained in more detail using a preferred embodiment and with reference to the drawings. They show: Fig. 1 a perspective view of a rear axle module according to the invention for connection to a rear vehicle structure of a motor vehicle body; Fig. 2 a perspective sectional view along a sectional plane extending in the region of a central longitudinal axis of the motor vehicle, in the vehicle vertical direction and in the vehicle longitudinal direction through the rear axle module according to Fig. 1, on which an internal combustion engine is arranged and in front of whose cross element both a tank for the internal combustion engine and an energy storage device for an electric drive of the motor vehicle are accommodated, Fig. 3 a partial and perspective sectional view through the rear axle module analogous to Fig. 2, where a car body made of carbon fiber reinforced plastic can also be seen, to which the rear axle module is connected from below.

[0020] Fig. 1 shows a perspective view of a rear axle module 1 for a passenger car, which is furthermore used in conjunction with the Fig. 2 and Fig. 3 can be connected to a rear structure 2 of a motor vehicle body.

[0021] The rear axle module 1 comprises a rear frame structure 3 with respective lower longitudinal members 4, which are connected to each other at the rear end via a lower cross member 5 and respective front cross member stubs 6. In a central area, the two lower longitudinal members 4 are connected to each other via a central cross member 7. In this case, the respective longitudinal members and cross members 4 to 7 are manufactured, for example, as profile parts made of an extruded profile. Of course, any other designs commonly used in the construction of rear axle modules are also conceivable.

[0022] From the frame structure 3 or the respective lower longitudinal member 4, a respective side structure 8, 9 projects upwards in the vertical direction of the vehicle, which are connected to one another at the rear end of the rear axle module 1 in their respective rear region via a rear transverse structure 10. The respective side structures 8, 9 comprise, as an essential element, a respective longitudinal member 11, 12, at the respective rear end of which a crash box 13 is arranged, by means of which a rear bumper cross member, which is not visible, can be supported on the rear axle module 1. The longitudinal members 11, 12 are connected to the frame structure 3 or the laterally corresponding lower longitudinal member 4 via a respective diagonally extending support 14, 15.In the rear area, the longitudinal members 11, 12 of the respective side structure 8, 9 are supported via respective corner members 16, 17 on the frame structure 3 in the respective corner area between the respective lower longitudinal member 4 and the lower cross member 5.

[0023] The rear transverse structure comprises an upper cross member 18 extending between the respective longitudinal members 11, 12, as well as respective diagonal members 19 extending between the cross member 18 and the lower cross member 5. In addition, the side structures 8, 9 comprise respective members 20, 21 extending on the upper side of the corresponding longitudinal members 11, 12.

[0024] As seen in conjunction with Fig. As can be seen in Figure 2, an internal combustion engine 22 is arranged on the rear axle module 1 between the respective side structures 8, 9 and in front of the rear transverse structure 10, or is supported by the latter. In this case, the internal combustion engine 22 serves to drive the motor vehicle, which is designed as a hybrid vehicle (PHEV). The internal combustion engine 22 is mounted on the rear axle module 1 via corresponding engine mounts.

[0025] As further seen in the summary of the Fig. 1 and Fig. 2, a front cross member 23 is arranged in front of the internal combustion engine, via which the side structures 8, 9 are connected to one another in their front region. Furthermore, the front cross member 23 is connected to the cross member 7 of the lower frame structure 3. In this case, the connection is made via respective detachable connecting means such as screws 24 or the like. In the present case, a front cross member in the form of a cross strut or a transverse shear field is created, which is fastened to the rear axle module 1 at three connection points, namely in an upper region in the front region of the corresponding side structure 8, 9 and in the central region of the cross member 7 of the lower frame structure 3.The cross element 23 is essentially V-shaped or T-shaped and is connected to the respective upper end regions 25 of the respective laterally associated side structures 8, 9 or to the central lower region of this support 7. The cross element 23, which in this case is at least essentially flat, extends slightly obliquely from the front bottom to the rear top. The detachability of the cross element 23 ensures the installation of the internal combustion engine 22 in the rear axle module 1 in a particularly favorable manner.

[0026] In front of the cross element 23 - as can be seen from Fig. 2 - on the one hand, a fuel tank 25 for the internal combustion engine is arranged, which is essentially U-shaped in plan view. The fuel tank 25 has respective lateral parts 26, 27 and a central rear part 28, which surround a rear region of an energy storage device 29 arranged within a center tunnel, respectively, in a U-shape, laterally and rearwards. The fuel tank 25 is supported on the frame structure 3 or carried by it. In this case, a platform 31 arranged underneath the frame structure 3 can be provided both in the region of the fuel tank 25 and in the region of the internal combustion engine. The energy storage device 29 is also supported by its rear end in the region of this platform 30 on the frame structure 3. The energy storage device 29 penetrates the free space formed by the two cross member stubs 6.

[0027] In conjunction with Fig. Figure 3 shows how the rear axle module 1 is connected to the rear vehicle structure 3 of the motor vehicle body, which in this case is made of fiber-reinforced plastic. A heel wall 31 can be seen on the motor vehicle body, which divides a central vehicle floor 32 below a front row of vehicle seats from a rear vehicle floor 33 below a rear row of vehicle seats. Starting from the rear vehicle floor 33, a rear bulkhead 34 extends upward in the vertical direction of the vehicle, delimiting the passenger compartment of the vehicle to the rear. A rear floor structure 35 of the motor vehicle body extends above the combustion engine 22.

[0028] In particular from the Fig. 2 and Fig.3 thus clearly shows that the rear axle module 1 in question is an integral component of the motor vehicle body and, among other things, performs functions of the motor vehicle body. For example, the side structures 8, 9 of the rear axle module 1 serve to accommodate and support the chassis members of a rear axle, in particular for the articulated mounting of the respective chassis control arms. Furthermore, the longitudinal members 11, 12 of the rear axle module 1 perform the function of corresponding rear longitudinal members of the motor vehicle body, for example, for supporting a rear bumper or the associated bumper cross member.

[0029] By using the present cross element 23 in the form of a cross strut or transverse shear field, the static and dynamic rigidity of the rear axle module 1 or the rear structure 2 of the vehicle body can be significantly improved. This rigidity is increased by forming a transverse shear field throughout the entire rear axle module 1.

[0030] In addition, the shape of the cross member or cross strut 23 ensures the thermal insulation function between the internal combustion engine 2 and the components in front of it, in particular the tank 23 and the energy storage unit 29. A further advantage is that the cross member or cross strut 23 offers increased crash safety in the event of a rear-end collision. The design and rigidity of the cross member or cross strut 23 effectively prevent the internal combustion engine 22 and its periphery from penetrating the tank 25 and / or the energy storage unit 29 in front of it. Another major advantage is that the cross strut 23 can also serve as a support for other components.In particular, in a pre-assembly step, at least one component such as lines, engine control units or the like can be fastened to the cross member 23, wherein subsequently, as part of the final assembly, a complete arrangement of both the cross member 23 and the additional components takes place on the rear axle module 1. List of reference symbols 1 rear axle module 2 Rear car structure 3 Frame structure 4 lower longitudinal member 5 lower cross member 6 cross member stubs 7 middle cross member 8 Page structure 9 Page structure 10 rear transverse structure 11 longitudinal members 12 longitudinal members 13 Crashbox 14 carriers 15 carriers 16 corner supports 17 corner supports 18 upper cross member 19 diagonal beams 20 carriers 21 carriers 22 Internal combustion engine 23 front cross member 24 screws 25 Fuel tank Part 26 Part 27 Part 28 29 energy storage 30 Platform 31 heel wall 32 front vehicle floor 33 rear vehicle floor 34 rear bulkhead 35 Rear floor structure

Claims

[1] Rear axle module (1) for connection to a rear vehicle structure (2) of a motor vehicle body, with a lower frame structure (3) and respective side structures (8, 9) projecting upwards from the frame structure (3) in the vertical direction of the vehicle, to which respective chassis components of a rear axle can be fastened, with a rear transverse structure (10) at the rear end of the rear axle module (1), via which the side structures (8, 9) are connected to one another in a rear region, and with a front transverse element (23), via which the side structures (8, 9) are connected to one another in a front region, characterized by that an internal combustion engine (22) is arranged on the frame structure (3) between the side structures (8, 9), the rear transverse structure (10) and the transverse element (23). [2] Rear axle module (1) according to claim 1, characterized bythat the front cross member (23) is also connected to a cross member (7) of the lower frame structure (3). [3] Rear axle module (1) according to claim 1 or 2, characterized by that the front cross element (23) is detachably connected to the side structures (8, 9) and / or the cross member (7) of the lower frame structure (3). [4] Rear axle module (1) according to claim 3, characterized by that the front cross element (23) is V-shaped and is connected with respective upper end regions to the laterally associated side structure (8, 9) and with a central lower region to the cross member (7) of the lower frame structure (3). [5] Rear axle module (1) according to one of the preceding claims, characterized by that a fuel tank (25) for the internal combustion engine (22) is arranged in front of the front cross member (23). [6] Rear axle module (1) according to one of the preceding claims, characterized bythat an electrical energy storage device (29) of the drive of the motor vehicle is arranged in front of the front transverse element (23). [7] Rear axle module (1) according to one of the preceding claims, characterized by that at least one component is pre-assembled on the front cross element (23).

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