Driving assembly comprising a rolling differential

The invention relates to a driving assembly for a vehicle, including an electric machine and a transmission device that is connected thereto, further having a differential and a spur gear that drivingly couple a first output shaft and a second output shaft to the electric machine. According to the invention, the differential is embodied as a rolling differential; the first output shaft is drivingly connected to the rolling differential, and the second output shaft is drivingly connected to the spur gear.

BACKGROUND

The invention relates to a drive arrangement for a vehicle with an electric machine and a transmission device connected to this electric machine, comprising a differential and a spur gear that provide a drive connection of a first and a second driven shaft with the electric machine.

FIELD OF THE INVENTION

DE 10 2007 055 767 A1 discloses an electric drive for a vehicle with an electric motor that drives two outputs via a spur gear transmission and a differential gear unit. In particular, the electric motor drives, with its motor shaft, a first spur gear that is in active connection with a second spur gear that is locked in rotation via an intermediate shaft with a third spur gear. The third spur gear is in active connection with a fourth spur gear that is locked in rotation with a differential cage of the differential gear unit. Thus, the spur gear transmission has, in total, four spur gears.

The disadvantage of the previously mentioned prior art consists in that the transmission arrangement, in particular, the spur gear transmission has many transmission parts, in particular, spur gears. Therefore, the entire transmission arrangement requires a relatively large amount of installation space. Furthermore, due to the four spur gears, the efficiency of the transmission is lowered and the weight is increased.

SUMMARY

Therefore, the objective of the present invention is to create a drive arrangement with a differential and a spur gear that has a compact construction and is optimized with respect to weight and has a high efficiency.

According to the invention, the differential is constructed as a rolling differential, wherein the first driven shaft is in drive connection with the rolling differential and the second driven shaft is in drive connection with the spur gear. A wheel for driving the vehicle is arranged at least indirectly on each of the two driven shafts. Thus, the first driven shaft represents a first power take-off and the second driven shaft represents a second power take-off of the drive arrangement.

The electric machine is preferably in drive connection with the rolling differential via a sun shaft. The sun shaft is advantageously connected directly to the electric machine. Furthermore, however, the sun shaft can also have a two-part construction. In particular, an electric motor, comprising a rotor and a stator, is used as the electric machine.

In an especially preferred way, the sun shaft meshes with a planet set supported on a planet carrier so that it can rotate. In particular, the planet set meshes radially between the sun shaft and a ring gear. In other words, the rolling differential comprises the sun shaft acting as power intake and the planet set that is supported on the planet carrier so that it can rotate and that is arranged radially between the sun shaft and the fing gear. Therefore, the rolling differential has an especially compact construction.

In addition, the planet carrier is preferably coupled with the first driven shaft. Consequently, the planet carrier is used as a first power take-off of the rolling differential.

The invention includes the technical teaching that the ring gear has external teeth and meshes with the spur gear. Thus, the ring gear meshes both with the planet set of the rolling differential and also with the spur gear. Here, the ring gear represents a second power take-off of the rolling differential.

According to a preferred embodiment, the first and the second driven shafts are arranged parallel and have an axial offset. In other words, the two driven shafts are not located on a common axis, but instead at a radial distance from each other. This produces, in particular, savings with respect to installation space in the axial direction of the driven shafts.

Preferably, the axial offset of the two driven shafts can be offset by an articulated shaft connected to each of the first and second driven shafts. Thus, the two articulated shafts allow the compensation of the axial offset under the use of simple and compact components. Also conceivable is, for example, the use of constant-velocity joints or the like for compensating the axial offset.

According to another preferred embodiment, the first and second driven shafts are arranged on a common axis, wherein at least the transmission device has an angle of rotation that is between 10° and 80° with regard to the common axis of the two driven shafts. In other words, at least the transmission device is rotated by the angle of rotation, so that the two driven shafts are arranged on a common axis due to this rotation. Therefore, the previously mentioned articulated shafts for compensating the axial offset are eliminated. Furthermore, it is also conceivable to rotate the electric machine, in addition to the transmission device, by the angle of rotation, so that the entire drive arrangement is rotated up to the two driven shafts. An angle of rotation of 0° here represents the transverse installation of the drive arrangement in the vehicle, wherein an angle of rotation of 90° represents a longitudinal installation of the drive arrangement in the vehicle.

In an especially preferred way, the angle of rotation is between 30° and 60° with respect to the common axis of the two driven shafts. In particular, the angle of rotation is between 40° and 50° with respect to the common axis of the two driven shafts.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

According toFIGS. 1 and 2, a drive arrangement according to the invention for a vehicle has an electric machine1and a transmission device2connected to this electric machine. The transmission device2includes a rolling differential3and a spur gear4, wherein the rolling differential3interacts in a driving manner via a planet carrier7with a first driven shaft5aand the spur gear4interacts in a driving manner with a second driven shaft5b. A sun shaft6connects the electric machine1to the rolling differential3and thus represents a power input of the rolling differential3. The sun shaft6here meshes with a planet set8that is supported on the planet carrier7so that it can rotate and that meshes with a ring gear9on its side. The ring gear9further has external teeth10and meshes via these teeth with the spur gear4. The drive arrangement thus allows a power distribution in the rolling differential3that is constructed as a planetary gear and a high transmission ratio with a high efficiency.

According toFIG. 1, the first and the second driven shafts5a,5bare arranged parallel and have an axial offset. The axial offset of the two driven shafts5a,5b, however, is compensated by an articulated shaft11a,11bthat is connected to each of the first and second driven shafts5a,5b. The two articulated shafts11a,11bconnect the two driven shafts5a,5bwith a wheel of the vehicle arranged on a common axis12—not shown here.

According toFIG. 2, the first and second driven shafts5a,5bare arranged on a common axis12, wherein the transmission device2and the electric machine1have an angle of rotation13that is 50° with respect to the common axis12of the two driven shafts5a,5b. The two driven shafts5a,5bare each connected to a wheel of the vehicle—not shown here.

LIST OF REFERENCE NUMBERS