Transmission for a motor vehicle

Abstract

Transmission (10) for a motor vehicle (12), comprising a rotor shaft (1) which can be driven by an electric machine (EM) and a planetary gear set (PS), wherein the rotor shaft (1) has an internal toothing (2) in a ring gear receiving section (21) which engages with an external toothing (16) of a ring gear (3) of the planetary gear set (PS) and the rotor shaft (1) has a rotor receiving section (22) for receiving a rotor (4), characterized in that the rotor shaft (1) is bent between the rotor receiving section (22) and the ring gear receiving section (21).

Description

[0001] The invention relates to a transmission for a motor vehicle, comprising a rotor shaft that can be driven by an electric machine and a planetary gear set, wherein the rotor shaft has internal teeth in a ring gear receiving section which engage with external teeth of a ring gear of the planetary gear set, and the rotor shaft has a rotor receiving section for receiving the rotor. Furthermore, the invention relates to a motor vehicle with the transmission according to the invention.

[0002] A variety of differently designed transmissions used in motor vehicles are known from the prior art. For example, transmissions are known that incorporate an electric motor to enable hybrid driving. The electric motor can be connected to a transmission input shaft via a reduction gear.

[0003] From DE 10 2008 040 495 A1, a gearbox is known that comprises an electric machine and a planetary gear set connected to the rotor of the electric machine. In this gearbox, a rotor carrier acts as the ring gear of the planetary gear set. The gearbox has the disadvantage that no standardized components can be used for the planetary gear set, and therefore the manufacturing of the individual components of the gearbox is cumbersome.

[0004] From JP 2012 037 016 A, a drive unit for a motor vehicle is known, comprising an electric machine and a transmission. A rotor of the electric machine is mounted on the outside of the rotor shaft. A rotor shaft of the transmission has internal teeth on its inside surface, which mesh with external teeth of a ring gear. A disadvantage of the drive unit is that the rotor shaft is solid and therefore has a comparatively high mass.

[0005] The object of the invention is therefore to provide a gearbox, a structurally simple connection between the ring gear and the rotor, which requires little material and little installation space.

[0006] The problem is solved by a gearbox of the type mentioned above, characterized in that the rotor shaft is bent between the rotor mounting section and the ring gear mounting section. "Bent" here refers to a contour that can be produced, for example, by deep drawing.

[0007] The transmission according to the invention has the advantage that the bending between the rotor mounting section and the ring gear mounting section bridges a radial distance, relative to a transmission center axis, between the ring gear and the rotor. This results in a rotor shaft with high stiffness while requiring minimal material. In this way, maintaining the air gap between the rotor and stator of the electric machine can be ensured with minimal material usage.

[0008] Furthermore, an advantage of this gearbox is that the ring gear and the rotor shaft are not manufactured as a single piece, but as separate components. This allows the gearbox to use a planetary gear set consisting of standardized gear set elements, thus simplifying its production. By incorporating a profiled tooth profile, particularly an internal tooth profile, into the rotor shaft, a small contact area between the ring gear and the rotor shaft can be achieved, both axially and radially, relative to the gearbox's central axis. The internal tooth profile is preferably produced using internal punches.

[0009] The term "shaft" does not exclusively refer to a cylindrical, rotatably mounted machine element for transmitting torques, but rather also includes general connecting elements that connect individual elements together, in particular connecting elements that connect several elements together in a rotationally fixed manner.

[0010] A rotationally fixed connection is a connection between two elements designed such that the two connected elements always rotate at the same speed. This is not the case, for example, if a switching element is located between the two connected elements and is in the open position. A rotationally fixed connection can be achieved, for example, by means of a splined connection.

[0011] The electric machine consists of at least a stator and a rotatably mounted rotor and is designed in motor operation to convert electrical energy into mechanical energy in the form of speed and torque, and in generator operation to convert mechanical energy into electrical energy in the form of current and voltage.

[0012] In a special embodiment, the rotor shaft can have a bent section that is rotationally fixed to the ring gear mounting section and the rotor mounting section. The bent section can separate the ring gear mounting section and the rotor mounting section from each other radially with respect to the transmission's central axis. Thus, the ring gear mounting section and the rotor mounting section cannot directly contact each other and / or are arranged at a radial distance from each other. The ring gear mounting section can run parallel to the rotor mounting section. As a result, the radial distance between the ring gear and the rotor can be bridged by appropriately designing the bent section.

[0013] The rotor shaft can have a support section that is directly supported, particularly in the radial direction, by a gearbox input shaft. The rotor shaft can be supported at one end by means of this support section against the gearbox input shaft. At another end of the rotor shaft, the rotor can be non-rotatably connected to the rotor mounting section.

[0014] The rotor shaft can also have a radial section that connects the support section and the ring gear mounting section in a rotationally fixed manner. In particular, the radial section can separate the support section and the ring gear mounting section from each other in the radial direction with respect to the transmission's central axis. The radial section can be supported axially by means of a first thrust bearing and a second thrust bearing. The radial section can be supported by means of the first thrust bearing against a component of a disconnect coupling, in particular directly. In a multi-plate clutch configuration, the radial section can be supported by means of the first thrust bearing against a plate carrier of the multi-plate clutch. Furthermore, the radial section can be supported by means of the second thrust bearing against a web of the planetary gear set, in particular directly.

[0015] In a special embodiment, the gearbox can include the electric machine, wherein the rotor of the electric machine is non-rotatably connected to the rotor mounting section of the rotor shaft and / or is attached to the rotor shaft, in particular the rotor mounting section.

[0016] The planetary gear set's web can be non-rotatably connected to the transmission input shaft. A sun gear of the planetary gear set can be non-rotatably connected to a housing, particularly a transmission housing. This means that the sun gear does not rotate during transmission operation. The planetary gear set can be arranged coaxially with the transmission's central axis.

[0017] The transmission can include a main transmission. The main transmission can be an automated transmission comprising several gear sets, in particular planetary gear sets and / or gears, in particular spur gears, and shift elements. The transmission input shaft can be mechanically connected to, or connectable to, at least one gear set of the main transmission. By closing at least one, in particular several, shift elements, multiple gears with different ratios can be achieved between the transmission input shaft and a transmission output shaft.

[0018] The rotor shaft can have a stop against which the ring gear rests. This stop can limit the axial movement of the ring gear relative to the transmission's central axis. Furthermore, the stop can be integrally formed with the rest of the rotor shaft. In particular, the stop can be created by applying a force towards the ring gear on a side of the rotor shaft furthest from the ring gear. Alternatively or additionally, an output-side axial stop for the ring gear can be achieved by means of a rivet.

[0019] The transmission can be a component of a motor vehicle, which is then driven by the transmission's electric motor. The planetary gear set, positioned in the power flow between the electric motor and the transmission input shaft, allows the electric motor to be designed for higher speeds. This, in turn, permits a smaller electric motor design.

[0020] The invention is schematically represented in the figures and is described below with reference to the figures, whereby identical or equivalently acting elements are mostly provided with the same reference numerals. The figures show: Fig. 1 a sectional view of a section of the transmission according to the invention, Fig. 2 an enlarged view of the connection area between the ring gear and the rotor shaft, Fig. 3 a motor vehicle with the transmission according to the invention,

[0021] The in Fig. Section 1 of the gearbox 10 shown has a rotor shaft 1 driven by an electric machine EM and a planetary gear set PS. The rotor shaft 1 has an internal tooth 2 in a ring gear mounting section 21, which engages with an external tooth 16 of a ring gear 3 of the planetary gear set PS. The rotor shaft 1 also has a rotor mounting section 22 for receiving a rotor 4. In particular, the rotor 4 is non-rotatably connected to the rotor mounting section 22. Furthermore, the rotor shaft 1 is bent between the rotor mounting section 22 and the ring gear mounting section 21. Fig. Figure 1 shows only one section of the gearbox 10.

[0022] The rotor shaft 1 also has a bent section 23, which is arranged between the rotor mounting section 22 and the ring gear mounting section 21. The bent section 23 is non-rotatably connected to the ring gear mounting section 21 and the rotor mounting section 22. In particular, the rotor mounting section 22 is non-rotatably connected to one end of the bent section 23, and the ring gear mounting section 21 is non-rotatably connected to the other end of the bent section 23. Both the rotor mounting section 22 and the ring gear mounting section 21 extend from the bent section 23 in the same axial direction with respect to the transmission center axis M and are parallel to each other. The rotor mounting section 22 and the ring gear mounting section 21 are spaced apart from each other in the radial direction with respect to the transmission center axis M.

[0023] The rotor shaft 1 has a support section 24 at one end, which is directly supported on a gearbox input shaft 5 of the gearbox 10. The rotor mounting section 22 is arranged at one end of the rotor shaft 1. The rotor shaft 1 also has a radial section 25, which is arranged between the support section 24 and the ring gear mounting section 21. The support section 24 is rotationally fixed to one end of the radial section 25, and the ring gear mounting section 21 is connected to the other end of the radial section 25. The support section 24 and the ring gear mounting section 21 extend from the radial section 25 in different axial directions.

[0024] A sun gear 17 of the planetary gear set PS is non-rotatably connected to a housing G of the gearbox. A web 6 of the planetary gear set PS is non-rotatably connected to the gearbox input shaft 5.

[0025] The gearbox 10 has a main gearbox HG, which is in Fig. Figure 1 is shown only schematically. The transmission input shaft 5 is mechanically connected, or can be mechanically connected, to at least one gear set (not shown) of the main transmission HG. The main transmission HG also has shifting elements (not shown). Different gears with different ratios can be achieved using the gear sets and the shifting elements.

[0026] The gearbox 10 is connected to a disconnect clutch K0 in Fig. 1. The vehicle drive unit VM (not shown) can be connected to the drive system. The disconnect clutch K0 is designed as a multi-plate clutch, with a first plate carrier 7 being rotationally fixed to the transmission input shaft 5. A second plate carrier 8 is connected to the transmission input shaft 5 via a torsional vibration damper. Fig. The radial section 25 is operatively connected to the motor vehicle drive unit VM (not shown). The radial section 25 is supported directly on the first lamellar carrier 7 by means of a first axial bearing 26. In addition, the radial section 25 is supported directly on the web 6 by means of a second axial bearing 15.

[0027] Fig. Figure 2 shows an enlarged view of the connection area between the ring gear 3 of the planetary gear set PS and the rotor shaft 1, in particular the ring gear mounting section 21. As can be seen from Fig. As can be seen in Figure 2, the ring gear 3 is supported axially against a stop 9. The stop 9 is created by applying a force to a side 13 of the rotor shaft 1 facing away from the ring gear 3, with the force being directed towards the ring gear 3. As a result of the force being applied, a section of material from the rotor shaft 1, corresponding to the stop 9, is moved towards the ring gear 3. After the stop 9 has been created, the rotor shaft 1 has a recess 14.

[0028] Fig. Figure 3 shows a motor vehicle 12 whose drive train includes the transmission 10 according to the invention. As shown in Figure 3, the drive train includes the transmission 10 according to the invention. Fig.As can be seen in Figure 3, the transmission input shaft 5 can be connected to the vehicle drive unit VM by means of the disconnect clutch K0. The vehicle drive unit VM can be designed as an internal combustion engine. The transmission 10 can be connected to other vehicle components not shown, such as an axle differential, by means of a transmission output shaft 11. Reference sign 1 rotor shaft 2 Internal teeth 3. Ring gear 4 Rotor 5 Gearbox input shaft 6 Bridge 7 first lamellar carrier 8 second lamellar carrier 9 attacks 10 gearboxes 11 Transmission output shaft 12 Motor vehicle Page 13 of rotor shaft 14 recess 15 second axial bearing 16 External teeth 17 Sun wheel 21 Ring gear mounting section 22 Rotor mounting section 23 Bending section 24 Support section 25 Radial section 26 first axial bearing G Housing L Central axis of the rotor shaft M Transmission center axle K0 disconnect coupling EM electric machine HG main gearbox PS planetary gear set VM automotive drive unit

Claims

[1] Transmission (10) for a motor vehicle (12), comprising a rotor shaft (1) which can be driven by an electric machine (EM) and a planetary gear set (PS), wherein the rotor shaft (1) has an internal toothing (2) in a ring gear receiving section (21) which engages with an external toothing (16) of a ring gear (3) of the planetary gear set (PS) and the rotor shaft (1) has a rotor receiving section (22) for receiving a rotor (4), characterized by , that the rotor shaft (1) is bent between the rotor mounting section (22) and the ring gear mounting section (21). [2] Gearbox according to claim 1, characterized by , that the rotor shaft (1) has a bending section (23) which is non-rotatably connected to the ring gear mounting section (21) and the rotor mounting section (22) and separates the ring gear mounting section (21) and the rotor mounting section (22) from each other in a radial direction. [3] Gearbox according to claim 1 or 2, characterized by, that the ring gear mounting section (21) runs parallel to the rotor mounting section (22). [4] Gearbox according to any one of claims 1 to 3, characterized by , that the rotor shaft (1) has a support section (24) which is directly supported on a gearbox input shaft (5) of the gearbox (10). [5] Gearbox (10) according to claim 4, characterized by , that the rotor shaft (1) is supported at one end by means of the support section (24) on the gearbox input shaft (5) and that at another end of the rotor shaft (1) the rotor (4) is connected to the rotor receiving section (22) in a rotationally fixed manner. [6] Gearbox according to claim 4 or 5, characterized by , that the rotor shaft (1) has a radial section (25) which is non-rotatably connected to the support section (24) and the ring gear mounting section (21), wherein the radial section (25) is supported in the axial direction by means of a first axial bearing (26) and a second axial bearing (15). [7] Gearbox according to claim 6, characterized by , that the radial section (25) can be supported on a component of a disconnect coupling (K0) by means of the first axial bearing (26). [8] Gearbox (10) according to any one of claims 1 to 7, characterized by the electric machine (EM), wherein the rotor (4) of the electric machine (EM) is connected to the rotor receiving section (22) of the rotor shaft (1) in a rotationally fixed manner. [9] Gearbox (10) according to any one of claims 4 to 8, characterized by , that a bridge (6) of the planetary gear set (PS) is connected to the transmission input shaft (5) of the transmission (10) in a rotationally fixed manner. [10] Gearbox (10) according to any one of claims 1 to 9, characterized by , that the rotor shaft (1) has a stop (9) against which the ring gear (3) rests. [11] Drive train for a motor vehicle comprising a transmission (15) according to any one of claims 1 to 10, characterized by , that the motor vehicle can be driven by means of the electric machine (EM) of the transmission (G).

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