Rear-wheel drive module of a vehicle

Abstract

The present invention relates to a rear-wheel drive module (1) of a vehicle (100) and a vehicle (100) with a rear-wheel drive module (1) according to the invention. The rear-wheel drive module (1) according to the invention, for driving the rear wheels (41) of a vehicle (100), comprises an internal combustion engine (10) with at least one cylinder bank arranged horizontally and various engine peripheral elements. Furthermore, the rear-wheel drive module (1) comprises a transmission (20) which is arranged in the power transmission between the internal combustion engine (10) and the rear wheels (41) of the vehicle (100). In addition, a first electric motor (30) is provided, which is integrated into a drive train of the vehicle. The first electric motor (30) further comprises power electronics (31) connected to it.Furthermore, the rear drive module (1) has a rear axle structure (40) for attaching the rear drive module (1) to the vehicle (100), wherein the rear axle structure (40) is designed such that the rear drive module (1) does not extend further forward in the longitudinal direction of the vehicle than the rear wheels (41) of the vehicle (100).

Description

[0001] The present invention relates to a rear-wheel drive module of a vehicle and a vehicle with a rear-wheel drive module according to the invention. Within the scope of the present application, a rear-wheel drive module is understood to be a vehicle assembly that includes the drive units and power conversion devices necessary for driving a rear axle of the vehicle.

[0002] In the past, vehicle concepts with hybrid drive systems combining an internal combustion engine (ICE) and an electric motor (EM) often incorporated the elements for the electric drive into existing vehicle architectures developed for ICE vehicle concepts. Thus, the required additional devices and energy storage units were installed wherever space could be made available, without taking ideal placement into account. The result was a constant compromise between various optimization goals, such as range, vehicle safety, low center of gravity, etc., with regard to vehicle design.

[0003] In the meantime, most OEMs have moved toward developing dedicated BEV platforms whose dimensions are specifically designed to accommodate a high-voltage battery, its infrastructure, and the electric drive systems. The so-called skateboard architecture has become established: one or more high-voltage batteries on the front and rear axles, with a flat high-voltage battery (HVB) in the main floor of the vehicle between them. This architecture represents the best possible compromise, based on the state of the art, between the dimensioning of the power storage unit, vehicle safety, the lowest possible center of gravity, and optimal use of space in the passenger compartment. However, the transformation from ICEs to purely electric vehicles is taking place at widely varying speeds in global markets.

[0004] This depends primarily on the development of local infrastructure, but also on the area of ​​operation and thus the required range of the vehicles (rural states vs. metropolitan areas). It is expected that conventional ICE-based vehicle concepts will continue to be required and built alongside pure BEV vehicles for a relatively long time. This poses a major challenge for vehicle manufacturers. The new BEV platforms in their current form are generally not compatible with conventional ICE platforms, which means that either many platforms have to be developed and built in parallel in factories, or a focus on one drive type is required, thus preventing alternative drive offerings. This entails a higher entrepreneurial risk.

[0005] So-called multi-traction architectures can help mitigate this risk. Here, the vehicle architecture is designed to allow the integration of several different drive sources. However, the resulting drive flexibility is usually achieved at the cost of technical compromises. This raises the question of what such a multi-traction architecture could look like in order to minimize the need to make compromises for different drive concepts. While the vast majority of combustion engine platforms feature a center tunnel in which the exhaust duct and drive shaft can be routed from the combustion engine on the front axle to the rear axle or the end of the vehicle, the skateboard architecture of purely battery-electric vehicles provides precisely this location for the HVB.

[0006] Patent document DE 10 2021 122 044 A1 discloses a drive axle for a motor vehicle having an internal combustion engine, an electric motor and a transmission, wherein the crankshaft of the internal combustion engine is arranged in front of the wheel hubs with respect to a forward direction of the drive axle.

[0007] From the patent document DE 10 2010 033 431 A1 a vehicle is known which has an internal combustion engine, an electric motor and a generator, wherein the internal combustion engine generates the generator for generating power for the electric motor.

[0008] The aim of the present invention is therefore to provide a rear-wheel drive module that can be used to easily create a multi-traction architecture for different drive concepts. It is also the aim of the present invention to provide a vehicle with the rear-wheel drive module according to the invention.

[0009] This object is achieved by the subject matter of the independent claims. Advantageous embodiments are disclosed by the subject matter of the subclaims.

[0010] The rear-wheel drive module (1) according to the invention for driving the rear wheels (41) of a vehicle (100) has an internal combustion engine (10) with at least one cylinder bank arranged horizontally and various peripheral engine elements. Peripheral engine elements are understood to mean elements and devices that enable or improve the operation of the engine. These include, for example, the cooling system, electrical elements, fuel supply system, intake and exhaust system, turbo system, exhaust aftertreatment system, and other devices directly connected to the engine. A cylinder bank is referred to as a horizontally arranged cylinder bank if the stroke direction of the pistons arranged therein extends essentially horizontally. Essentially horizontal is understood to mean a horizontal arrangement with a maximum deviation of 10 degrees.

[0011] The rear-wheel drive module also has a transmission that is arranged in the power transmission between the combustion engine and the rear wheels of the vehicle. A first electric motor is also provided that is integrated into a drive train of the vehicle. This includes any configuration of the electric motor in which it can transmit power to the drive train or absorb it in generator mode. For this purpose, it can, for example, transmit power to or absorb power from an input shaft of the transmission or an output shaft of the transmission. It can also be arranged upstream of or downstream of a clutch in the direction of action. A configuration is also conceivable in which the electric motor is arranged upstream of the combustion engine in the direction of action and can thus exert power on the crankshaft, for example, via a belt.All common parallel hybrid architectures are included, which, according to common practice, are classified into categories P0 to P4 depending on the position of the electric motor. The first electric motor also has power electronics connected to it. Embodiments with more than one first electric motor are also conceivable; therefore, the phrase "a first electric motor" should be understood as "at least one first electric motor."

[0012] Furthermore, the rear-wheel drive module has a rear axle structure for attaching the rear-wheel drive module to the vehicle, wherein the rear axle structure is designed such that the rear-wheel drive module does not extend further forward in the longitudinal direction of the vehicle than the rear wheels of the vehicle. In other words, the rear-wheel drive module does not protrude in the longitudinal direction of the vehicle beyond an imaginary connection of the points of the two rear wheels that are furthest forward in the direction of travel of the vehicle. The longitudinal direction of the vehicle is to be understood as the direction of travel of the vehicle when driving straight ahead. The “front” and “rear” of the vehicle are defined by the front axle and rear axle. On the side of the vehicle in the longitudinal direction on which the rear axle is arranged, the rear of the vehicle is located, while on the side of the vehicle in the longitudinal direction on which the front axle is arranged, the front of the vehicle is located.The longitudinal direction of the vehicle runs from the rear axle to the front axle. For the purposes of this application, the rear axle structure refers to a subframe or subframe of a vehicle. Accordingly, the rear axle structure also determines the position of the rear wheels in relation to the components of the rear-wheel drive module attached to the rear axle structure.

[0013] The rear-wheel drive module according to the invention enables a multi-traction vehicle architecture based on a skateboard architecture, which is particularly advantageous for battery-electric vehicles. This eliminates the need to make compromises regarding the drive and the arrangement of the individual components when designing hybrid-powered vehicles.

[0014] In an advantageous embodiment of the rear-wheel drive module according to the invention, the internal combustion engine is designed as a boxer engine or as a 180° V-engine. In a V-engine, the cylinder banks are usually arranged in a V-position relative to one another. In a 180° V-engine, however, the cylinder banks are arranged in one plane. The difference between a boxer engine and a 180° V-engine is that in a boxer engine, two opposing pistons always move synchronously in opposite directions, whereas in a 180° V-engine, parallel movement of two opposing pistons is also possible. The crankshafts and the attachments of the connecting rods to the crankshafts are therefore designed differently. Such ICE designs have the advantage of being very low in height and can therefore be arranged lying flat in the vehicle.

[0015] In an advantageous embodiment of the invention, a crankshaft of the internal combustion engine is arranged in the longitudinal direction of the rear-wheel drive module, and the transmission is designed as a transverse transmission. Thus, power is transmitted from the crankshaft to a transmission input shaft oriented in the vehicle's longitudinal direction and to a transmission output shaft arranged transversely to the transmission input shaft. The two shafts are thus offset from one another by an angle of approximately 90°. A deviation may occur, for example, if the ICE is not installed exactly in the longitudinal direction. A transverse transmission is therefore to be understood as a transmission which, depending on the design, is capable of enclosing an angle, in particular 90 degrees, between power input and power output. Such a design enables particularly compact designs of internal combustion engines in conjunction with transmissions in the longitudinal direction. Various types of transmissions are conceivable.

[0016] An embodiment of the combustion engine as a horizontal in-line engine is also conceivable. Even with such a design, particularly compact designs are possible. Such an embodiment is particularly preferred in conjunction with an engine crankshaft arranged transversely to the longitudinal direction of the rear-wheel drive module. Due to the fact that in-line engines usually require more installation space along the direction of the in-line arrangement than boxer engines or 180° V engines, the arrangement should be selected such that no change in direction between the input shaft and output shaft in the transmission is necessary in order to save installation space in the vehicle's longitudinal direction. The vehicle's longitudinal direction and the rear-wheel drive longitudinal direction are to be understood as having the same orientation for the purposes of this application, since they point in the same direction when the rear-wheel drive module is installed.

[0017] Another advantageous embodiment of the invention is one in which the transmission is integrated into a crankcase of the combustion engine. This also enables compact designs for the rear-wheel drive module.

[0018] A further preferred embodiment of the invention is one in which the internal combustion engine is arranged behind a rear wheel axle of the vehicle defined by the rear axle structure. The rear axle is defined by the rear axle structure, as this positions the suspension for the rear wheels and thus determines their position relative to the components arranged on the rear axle structure. The rear axle is understood to be the axle formed by the right and left rear wheels.

[0019] A further preferred embodiment of the invention is one in which the rear-wheel drive module has an exhaust system arranged behind the internal combustion engine in the longitudinal direction of the rear-wheel drive module. The position is specified relative to the geometric center of gravity, so that in this embodiment, the geometric center of gravity of the exhaust system is located behind that of the internal combustion engine.

[0020] Preferably, the electric motor with power electronics and / or a provided additional gear unit is designed within a module, i.e. within a housing, and thus represents a unit. This enables a compact modular design.

[0021] The vehicle according to the invention has a rear-wheel drive module according to the invention.

[0022] In a preferred embodiment of the vehicle according to the invention, HV battery cells are provided in a vehicle floor, in particular in the center section, to provide energy to operate the first electric motor arranged in the rear-wheel drive module. In this way, the skateboard architecture advantageous for a battery-electric vehicle is realized in a hybrid vehicle. Different embodiments with regard to the design of the HV battery are conceivable. Furthermore, a tank for fuel of the ICE is preferably provided at a location on the vehicle where, according to the skateboard architecture, an HV battery is provided. Thus, part of the space for HV batteries can be filled by a tank, in particular under the rear seat bench.

[0023] The vehicle can, for example, be configured as an all-wheel drive system by having a front-wheel drive module with a second electric motor, thus electrically powering the front axle. However, purely rear-wheel drive vehicle concepts are also conceivable. Other different drive concept options are also conceivable, in which the achievable range can be achieved purely electrically or solely through the ICE. For example, the ICE can also be configured as a hydrogen combustion engine, burning hydrogen.

[0024] The vehicle according to the invention has the advantage that no compromises need to be made regarding installation space or similar considerations when arranging the individual drive components, and sufficient space is available for both drive options. Thus, regardless of the exact design of a vehicle's drive concept, the same platform can be used, which significantly reduces the costs and design effort for a vehicle manufacturer.

[0025] Advantageous embodiments and aspects of the present invention are explained in more detail below with reference to the accompanying figures. They show: Fig. 1 shows a schematic representation of a rear-wheel drive module 1 of a vehicle 100 in an embodiment according to the invention in a perspective view Fig. 2 shows a schematic representation of a first embodiment of the vehicle 100 according to the invention with a rear-wheel drive module 1 according to the invention Fig. 3 shows a schematic representation of a second embodiment of the vehicle 100 according to the invention with a rear-wheel drive module 1 according to the invention Fig. 4 shows a schematic representation of a third embodiment of the vehicle 100 according to the invention with a rear-wheel drive module 1 according to the invention

[0026] Fig. 1 shows a schematic representation of a rear-wheel drive module 1 of a vehicle 100 in an embodiment according to the invention in a perspective view. The rear-wheel drive module 1 has an internal combustion engine 10 (ICE), on which an exhaust system 11 is arranged opposite to the longitudinal direction x of the rear-wheel drive module 1. This exhaust system 11 is positioned in particular such that its geometric center of gravity in the longitudinal direction x is arranged behind the geometric center of gravity of the internal combustion engine 10. The internal combustion engine 10 is arranged as a horizontal boxer engine, so that the cylinder banks of the internal combustion engine 10 are arranged horizontally. The crankshaft of the internal combustion engine 10 is arranged in the longitudinal direction.

[0027] Furthermore, a transmission 20 is provided, which transmits the power of the internal combustion engine 10 to the rear wheels 41. Due to the longitudinally arranged crankshaft of the internal combustion engine 10, the transmission 20 must be designed as a transverse transmission in order to be able to transmit the power from the crankshaft to the rear axle, which is arranged functionally transversely to the longitudinal direction and thus also to the direction of travel of the vehicle. In addition, a first electric motor 30 is provided, which can transmit power to the output shaft of the transmission 20. Likewise, power can be transmitted from the output shaft of the transmission 20 to the first electric motor 30 in order to be able to operate the first electric motor 30 in generator mode during a braking operation of the vehicle. The first electric motor 30 also has power electronics for its operation, which Fig. 1 is not explicitly shown. For the purposes of the application, it is understood that every electric motor also has power electronics, in particular in the form of a pulse-controlled inverter, regardless of whether this is specifically mentioned or shown in the figures or not.

[0028] The longitudinal direction x of the rear-wheel drive module 1 is equal to the vehicle's longitudinal direction. The counting is based on the vehicle's forward direction of travel in a positive direction.

[0029] The internal combustion engine 10, the transmission 20, and the first electric motor 30 are connected to a rear axle structure 40. This is to be understood as a supporting frame that carries the components but also defines the rear axle of the vehicle. The rear axle structure 40 also defines the position of the rear wheels 41. The rear axle structure 40 can therefore be understood as a subframe or subframe. The rear axle structure 40 can therefore be vibration-decoupled from the body of the vehicle 100 or not. The internal combustion engine 10, the transmission 20, and the first electric motor 30 are arranged on the rear axle structure 40 such that the entire rear-wheel drive module 1 extends no further forward in the longitudinal direction than the rear wheels 41. The internal combustion engine 10 is designed in particular as a rear engine and is thus arranged behind the rear axle.In this way, a compact design of the rear-wheel drive module 1 can be ensured, without taking up any installation space that would be required in a purely battery-electric vehicle with skateboard architecture for the electric drive or a corresponding HV battery.

[0030] Fig. Figure 2 shows a schematic representation of a first embodiment of a vehicle 100 according to the invention with a rear-wheel drive module 1 according to the invention. The basic concept of the vehicle 100 corresponds to a skateboard architecture of a purely battery-electric vehicle. Accordingly, the HV battery 50 is arranged in the floor of the vehicle's center section, which is located in the passenger compartment. The flat arrangement of the HV battery 50 ensures a low center of gravity. A tank 60 is provided under the rear seat, which supplies fuel for the combustion engine 10 of the rear-wheel drive module 1. In conventional vehicles with a skateboard architecture, additional HV batteries would be provided at this location to increase the electrical charging capacity.Accordingly, the additional HV batteries can simply be replaced by a tank without changing the basic architecture of the vehicle and thus properties such as weight distribution.

[0031] A second electric motor 80 is provided on the front axle of vehicle 100, which drives the front axle of the vehicle. Power electronics 31 in the form of a pulse-controlled inverter are also provided for this purpose. An air conditioning compressor 70 for the air conditioning system and a charging module 51, in particular an on-board charger, for charging the HV battery 50 are also provided. In order to provide cooling capacity for various components, one or more coolers 60 are also provided at the very front of the vehicle.

[0032] The rear-wheel drive module 1 according to the invention is arranged on the rear axle and includes the transmission 20, the combustion engine 10, an exhaust system 11, and the electric motor 30 including power electronics. In the illustrated embodiment, the vehicle 100 is thus designed as an all-wheel drive vehicle with a purely electrically driven front axle and a hybrid-driven rear axle.

[0033] Any other types of embodiments are also conceivable, such as in Fig. 3. This second embodiment of the vehicle 100 shown there does not have a driven front axle and is thus designed as a pure rear-wheel drive. It is also conceivable to enlarge the tank 60 and thus provide the tank 60 with volume, which is shown as an HV battery, in order to achieve a greater combustion range, as in Fig. 4. It is also conceivable to minimize the tank 60 and fill the freed volume with HV battery cells in order to increase the purely electric range.

[0034] Furthermore, it is conceivable to replace the tank 60 with a hydrogen tank 61, as in a third embodiment of the vehicle in Fig. 4 shown.

[0035] The rear-drive module 1 according to the invention thus enables the design of a multitude of different drive concepts with the same basic vehicle architecture, eliminating the need for a multitude of different platforms depending on the drive concept. It is necessary that the rear-drive module 1 does not extend forward in the longitudinal direction of the vehicle 100 beyond the rear wheels 41, so as not to restrict the skateboard architecture. Due to the rear-drive module 1, no center tunnel from the front of the vehicle to the rear of the vehicle is necessary, thus freeing up space on the floor of the center section for HV batteries.

[0036] If one were to use the embodiments according to the Fig.If the tanks (hydrogen tank 61 or “normal” tank 60) in each of Figures 2 to 4 were removed and additional HV batteries were provided in exactly the same position and the rear drive module according to the invention were replaced by a purely electrically operated rear drive module, one would arrive at the skateboard architecture of a battery-electric vehicle described at the beginning.

Claims

[1] Rear-wheel drive module (1) for driving rear wheels (41) of a vehicle (100), comprising an internal combustion engine (10) with at least one cylinder bank arranged horizontally and engine peripheral elements, a transmission (20) arranged in the power transmission between the internal combustion engine (10) and the rear wheels of the vehicle (100), a first electric motor (30) which is integrated into a drive train of the vehicle, with power electronics (31) connected thereto, a rear axle structure (40) for fastening the rear-wheel drive module (1) to the vehicle (100), wherein the rear axle structure (40) is designed such that the rear-wheel drive module (1) does not extend further forward in the longitudinal direction (x) of the vehicle than the rear wheels (41) of the vehicle (100). [2] Rear-wheel drive module (1) according to the preceding claim, wherein the internal combustion engine (10) is designed as a boxer engine or 180° V engine. [3] Rear-wheel drive module (1) according to one of the preceding claims, wherein a crankshaft of the internal combustion engine (10) is arranged in the longitudinal direction (x) of the rear-wheel drive module (1) and the transmission (20) is designed as a transverse transmission. [4] Rear-wheel drive module (1) according to the preceding claim 1, wherein the internal combustion engine (10) is designed as a horizontal in-line engine. [5] Rear-wheel drive module (1) according to the preceding claim 4, wherein a crankshaft of the internal combustion engine (10) is arranged transversely to the longitudinal direction (x) of the rear-wheel drive module (1). [6] Rear-wheel drive module (1) according to the preceding claim, wherein the transmission (20) is integrated in a crankcase of the internal combustion engine (10). [7] Rear-wheel drive module (1) according to one of the preceding claims, wherein the internal combustion engine (10) is arranged behind a rear wheel axle of the vehicle (100) defined by the rear axle structure (40). [8] Rear-wheel drive module (1) according to one of the preceding claims, wherein the rear-wheel drive module (1) further comprises an exhaust system (11) which is arranged behind the internal combustion engine (10) in the longitudinal direction (x) of the rear-wheel drive module (1). [9] Rear-wheel drive module (1) according to one of the preceding claims, wherein the electric motor (30) is formed with power electronics (31) and / or a provided additional transmission within a module. [10] Vehicle (100) comprising a rear-wheel drive module (1) according to one of the preceding claims. [11] Vehicle (100) according to the preceding claim, wherein HV battery cells (50) are arranged in a vehicle floor for providing energy for operating the first electric motor (30) arranged in the rear drive module (1). [12] Vehicle (100) according to one of the preceding claims 9 or 10, wherein the vehicle (100) comprises a front-wheel drive module with a second electric motor (80).

Images