drive unit

Abstract

Drive unit (100) for a hybrid vehicle with an internal combustion engine (102) having a crankshaft (104) rotatably mounted in an engine housing (108) and arranged to rotate about a first axis of rotation (d2), and an electric drive (101, 201, 301, 401) with an electric machine (110) having a rotor shaft (103, 203, 303) rotatably mounted in a machine housing (117, 217, 317) parallel to the crankshaft (104) about a second axis of rotation (d1), wherein the crankshaft (104) and rotor shaft (103, 203, 303) are connected by means of a module unit (105, 205) with a module housing (118, 218, 318) which contains a gear connection (111, 211, 411) whose meshing gears (112, 113, 212, 412) are mounted on radially spaced shaft sections (114, 115, 214, 314, 414) rotatably mounted in the module housing (118, 218, 318), and are connected to each other in a rotationally interlocking manner, characterized in that the rotor shaft (103, 203, 303) and a first of the shaft sections (114, 214,314, 414) are coaxially connected to each other without axial play by means of a conical press fit (116, 216, 316), the first shaft section (114, 214, 314, 414) has a central opening (222) in which a preload screw (221) axially preloads the conical press fit (116, 216, 316, 416) is received..

Description

[0001] The invention relates to a drive unit and an electric drive for this for a hybrid vehicle with an internal combustion engine having a crankshaft rotatably mounted in an engine housing and arranged to rotate about a first axis of rotation, and an electric machine having a rotor shaft rotatably mounted in a machine housing parallel to the crankshaft about a second axis of rotation, wherein the crankshaft and rotor shaft are connected to each other in a rotationally secure manner by means of a module unit with a module housing which contains a gear connection, the meshing gears of which are received on radially spaced shaft sections mounted in the housing.For example, a modular hybrid transmission with a drive unit is known from the publication DE 10 2021 126 768 A1, in which the crankshaft of the internal combustion engine and the rotor shaft of one of the two electric machines are arranged in parallel and are connected to each other by means of a gear connection in a rotationally locked manner.

[0002] Further prior art is referenced in DE 10 2021 126 768 A1. The object of the invention is the further development of a drive unit. In particular, the object of the invention is to avoid tolerance-related axial play between the rotor shaft and the module unit and the associated noise and wear.

[0003] The problem is solved by the subject matter of claims 1 and 8. The dependent claims describe advantageous embodiments of the subject matter of claims 1 and 8.

[0004] The proposed drive unit serves to power a motor vehicle, such as a hybrid vehicle, within a hybrid powertrain. The internal combustion engine can be a multi-cylinder engine that runs on conventional fuels like gasoline or diesel, on synthetic fuels (e-fuel), hydrogen, or similar substances. The internal combustion engine has a crankshaft that is rotatable about a first axis of rotation.

[0005] The drive unit also includes an electric motor with a rotor shaft arranged parallel to the crankshaft and rotatable about a second axis of rotation. The electric motor can, either alone or in conjunction with the internal combustion engine, power the vehicle or start the internal combustion engine. As a generator, the electric motor can recuperate kinetic energy from the vehicle and convert it into electrical energy, feeding it into a battery or accumulator, and / or, driven by the internal combustion engine, charging the battery or accumulator. The internal combustion engine can, alone or in conjunction with the electric motor, power the vehicle and / or charge the battery or accumulator. The internal combustion engine can be decoupled from the electric motor and / or the rest of the hybrid powertrain by means of a clutch, such as a friction clutch and / or a positive-lock clutch.Alternatively or additionally, the drag torque of the internal combustion engine can be reduced in certain drive situations, such as recuperation, electric driving, and the like, by means of appropriate valve control. Auxiliary components of the vehicle, such as the air conditioning, lubrication system, cooling system, and / or the like, can be driven by the electric motor and / or the internal combustion engine. A transmission with one or more switchable or automatically selected and shifted gear ratios can be connected downstream of the drive unit. Depending on the design of a single-axle or multi-axle driven vehicle, a differential, a transfer case with a differential lock, and / or the like can be arranged between the transmission and the drive wheels.The drive unit can be followed by one or more driving and / or recuperating electric motors, for example integrated into the gearbox or housed in a separate casing.

[0006] The crankshaft and rotor shaft, which are essentially parallel and radially spaced from each other, are connected to each other by means of a modular unit. This modular unit contains a housing in which a gear connection is located. The meshing gears of this connection are mounted on radially spaced shaft sections that are rotatably mounted within the housing. One shaft section, which holds the first gear, is rotationally fixed to the rotor shaft, and the other shaft section, which holds the other gear meshing with the first gear, is rotationally fixed to the crankshaft.

[0007] A gearbox input shaft can be connected to one of the shaft sections, for example, by means of a sliding spline connection, either in a rotationally fixed or rotationally locked manner. Advantageously, the connection is made to the shaft section that connects the crankshaft in a rotationally fixed way, so that the crankshaft and gearbox input shaft are coaxial to each other and the rotor shaft is arranged radially offset from the gearbox input shaft.

[0008] To create an axially backlash-free, and therefore noiseless and low-wear, connection between the rotor shaft and a first shaft section of the module unit arranged coaxially to it, the rotor shaft and this first shaft section are connected coaxially by means of a conical press fit, such as a tapered press fit. In contrast to a spur or circumferential gear connection, rattling of the gearing, for example during idling or load changes, is avoided. Furthermore, wear is minimized by the frictional engagement of the conical press fit.

[0009] The axial support of the assembly consisting of the rotor shaft and the first shaft section can be provided in a suitable manner either in the machine housing of the electric machine or in the module housing. For example, the first shaft section can be axially fixed in the module housing, and the rotor shaft can be axially supported in the machine housing with some play. Accordingly, the rotor shaft is supported by means of an axially free bearing in the machine housing. Alternatively, the rotor shaft can be axially fixed in the machine housing, and the first shaft section can be axially free in the module housing, so that the first shaft section is axially free in the module housing. Any axial misalignment that may occur between the shaft sections can be compensated for, for example, within the teeth of the gear connection and / or, if a gear is mounted separately on at least one shaft section, within this rotationally fixed connection.

[0010] The conical press fit is formed from a conical section, such as a conical core, pressed into a conical sleeve, with essentially the same, complementary cone angles. The conical section can be located on the shaft section and the conical sleeve on the rotor shaft. It has proven advantageous if the conical sleeve is machined onto the shaft section and the conical section onto the rotor shaft.

[0011] The tensioning of the conical press fit is advantageously achieved, for example, before the drive unit is connected to the gearbox, from the gearbox side, when the module unit is attached to the motor housing and / or the machine housing. For this purpose, the first shaft section has a central opening in which a preload screw, which axially preloads the conical press fit, is received. The preload screw is axially supported, for example, by its screw head against a stop surrounding the central opening and screwed in with a thread provided in the conical section.

[0012] To form a rotary connection that positively supports the conical press fit, an axially clearance-bearing face gear can be provided between the conical section and the conical sleeve.

[0013] The shaft sections are, for example, formed as a single unit with the respective gears. Alternatively, the shaft sections and the gears of the gear connection can be manufactured as separate parts. Different materials can be used for the gears and the shaft sections. Alternatively or additionally, different manufacturing and / or machining processes can be applied to the gears and the shaft sections. For example, the shaft sections can be manufactured from solid materials such as forged, sintered, or similar materials and machined with a specific and / or undefined cutting edge. The gears can, for example, be forged and then machined or formed from sheet metal. The gears are mounted on the shaft sections in a rotationally fixed manner and axially secured by means of a profile such as a toothed section.The gear teeth – the external teeth for forming the gear connection and / or the internal teeth for rotationally fixed mounting on the shaft section – can be rolled, broached, or manufactured in a similar manner. A mixed configuration of one-piece or two-piece shaft sections with gears in the module unit can also be advantageous.

[0014] Furthermore, an electric drive is proposed for a previously described drive unit, which comprises an electric machine with a rotor shaft rotatably mounted about a rotational axis in a machine housing and a module unit with a module housing containing a gear connection with meshing gears. The gears are mounted on radially spaced shaft sections supported in the housing, with the rotor shaft and a first of the shaft sections being coaxially connected to each other axially without backlash by means of a conical press fit. The electric drive forms a separate technical unit independent of the internal combustion engine, which as such can be arranged on the internal combustion engine, for example, by means of screws and centering devices attached to the engine housing or flanged to it.

[0015] Alternatively, the electric motor and the module unit can form separate assemblies, which include connections such as threaded connections and / or screws and centering devices for mounting on the internal combustion engine's housing. For example, the engine housing can have a radially extended flange, such as a radial flange, to which the electric motor is attached, for example, in the axial installation space on the radial flange, and the module unit is attached opposite it. In this case, the module unit can also be flanged to the engine housing surrounding the crankshaft.

[0016] The invention is described in the following: Fig. The exemplary embodiments shown in 1 to 4 are explained in more detail. These show: Fig. 1 a schematic representation of a drive unit, Fig. 2 the electric drive of the drive unit of the Fig. 1 in constructive design in section, Fig. 3 one compared to the electric drive of the Fig. 2 modified electric drives on average and Fig. 4 one opposite the Fig. 2 and Fig. 3 modified electric drives on average.

[0017] The Fig. Figure 1 shows a schematic side view of the drive unit 100 with the electric drive 101 containing the electric motor 110 and the internal combustion engine 102. The rotor shaft 103 of the electric motor 110, arranged about the axis of rotation d1, and the crankshaft 104 of the internal combustion engine 102, arranged parallel to it about the axis of rotation d2, are connected by means of the module unit 105 in a rotationally locked manner. The module housing 118 of the module unit 105 belonging to the electric drive 101 is centered on the engine housing 108 of the internal combustion engine 102 by means of the screws 106 and the centering sleeves 107 and connected to the machine housing 117 of the electric motor 110 by means of the screws 109. The module unit 105, or the engine housing 108, is connected, in a manner not shown, to a gearbox housing of a transmission downstream of the drive unit 100 in the hybrid drive train.

[0018] The rotationally fixed connection between the crankshaft 104 and the rotor shaft 103 is achieved by means of the gear connection 111, which is rotatably mounted in the module unit 105 and comprises meshing gears 112 and 113 that establish a predetermined gear ratio. Gear 112 is fixedly mounted on shaft section 114, which is rotatably mounted in the module unit 105 and is coaxial with the rotor shaft 103. Gear 113 is fixedly mounted on shaft section 115. In the illustrated embodiment, shaft section 115 is arranged coaxially with the crankshaft 104 and bolted to it. In this embodiment, shaft section 115 can form the transmission input shaft itself or a shaft section for connection to it. In other embodiments, the transmission can be connected by means of shaft section 114 or a transmission input shaft.

[0019] The torque transmission from the rotor shaft 103 to the shaft section 114 is effected by means of the conical press fit 116. Due to the axially backlash-free press fit between the rotor shaft 103 and the shaft section 114, a low-noise and low-wear coupling of the rotor shaft 103 to the gear connection 111 is achieved. In the Fig. Figures 2 to 4 show possible constructive embodiments of the electric drive 101 in partial section around the axis of rotation d1.

[0020] The Fig. Figure 2 shows the electric drive 201 with the machine housing 217 and the rotor shaft 203, which is rotatable about the axis of rotation d1 by means of the bearing 231. The module unit 205 with the module housing 218 shown in section contains the gear connection 211, of which only the shaft section 214 with the gear 212 integrally connected to it is shown.

[0021] The shaft section 214 and the rotor shaft 203 are arranged coaxially and connected to each other axially without play by means of the conical press fit 216. The rotor shaft 203 has a conical section 219 machined into its end, which is pressed into the conical sleeve 220 of the shaft section 214. The cone angle α between the conical section 219 and the conical sleeve 220 is, for example, 10° to 20°, preferably 14° to 16°. The conical press fit 216 is axially preloaded by means of the preload screw 221 arranged about the axis of rotation d1. For this purpose, the shaft section 214 has the central opening 222. The preload screw 221 is supported on the shaft section 214 by means of its screw head 223 and is screwed into the internal thread 224 of the rotor shaft 203. The preload screw 221 is screwed in through the central opening 225 in the module housing 218, which is arranged around the axis of rotation d1 and is sealed by means of the sealing screw 226.Optionally, a positive locking in the circumferential direction and axially clearance-bearing face gear 228 can be provided between the rotor shaft 203 and the shaft section 214.

[0022] The module housing 218 is sealed externally by means of the ring seal 227. To prevent axial over-constraint due to the compression fitting by means of the conical press fit 216, in the illustrated embodiment the shaft section 214 is axially fixed by means of bearings 229, 230 such as deep groove ball bearings or the like, while the rotor shaft 203 is rotatably supported with axial play relative to the machine housing 217 of the electric machine 210 by means of bearing 231, which is designed as a deep groove bearing or the like.

[0023] The Fig. Figure 3 shows the upper part of the electric drive 201, arranged around the axis of rotation d1. Fig. 2 similar electric drive 301 in partial section. In contrast to the electric drive 201, the mounting of the assembly formed by the conical press fit 316 from the rotor shaft 303 and the shaft section 314 is modified in the electric drive 301. In this embodiment, the axial fixed mounting of the rotor shaft 303 to the machine housing 317 is achieved, among other things, by means of the bearing 331, while the shaft section 314 is mounted axially with play relative to the module housing 318 by means of the bearings 329, 330.

[0024] The electric machine 310 and the module unit 305 are each sealed to the outside between machine housing 317 and rotor shaft 303 or between module housing 318 and shaft section 314 by means of ring seals 327, 332 such as lip seals, shaft ring seals or the like.

[0025] The Fig. Figure 4 shows the upper part of the assembly arranged around the axis of rotation d1, which includes the electric drives 201, 301. Fig. 2 and Fig. 3 similar electric drives 401 in partial section. In contrast to the electric drives 201, 301, the electric drive 401 has the gear connection 411, in which the shaft section 414 and the gear 412 and the - not shown - optionally complementary shaft section and the gear corresponding to the shaft section 115 and the gear 113 of the Fig. 1. The shaft section 414 and the gear 412 are formed in two parts. The shaft section 414 and the gear 412 are connected to each other in a rotationally fixed manner by means of the toothing 433. The gear 412 is supported axially on one side by the shoulder 434 of the shaft section 414 and on the other side by the bearing 429 and is thus axially fixed on the shaft section 414, since the bearing 429 is in turn axially fixed to the shaft section 414 by means of the retaining ring 435. Reference symbol list 100 drive units 101 Electric drive 102 Internal combustion engine 103 Rotor shaft 104 Crankshaft 105 module units 106 screw 107 Centering sleeve 108 Engine housings 109 screw 110 electric machine 111 Gear connection 112 gear 113 Gear 114 Wave section 115 Wave section 116 conical press bandage 117 machine housings 118 module housings 201 Electric drive 203 Rotor shaft 205 module units 210 electric machine 211 Gear connection 212 gear 214 Wave section 216 conical press bandage 217 machine housings 218 module housings 219 Cone section 220 Conical sleeve 221 Preload screw 222 Opening 223 Screw head 224 internal thread 225 opening 226 Sealing screw 227 Ring seal 228 Front teeth 229 warehouses 230 storage 231 warehouses 301 Electric drive 303 Rotor shaft 305 module unit 310 electric machine 314 Wave section 316 conical press bandage 317 Machine housings 318 module housings 327 Ring seal 329 warehouses 330 bearings 331 warehouses 332 Ring seal 401 Electric drive 411 Gear connection 412 gear 414 Wave section 429 warehouses 433 Gearing 434 Shoulder 435 retaining ring d1 axis of rotation d2 axis of rotation α Cone angle

Claims

[1] Drive unit (100) for a hybrid vehicle comprising an internal combustion engine (102) with a crankshaft (104) rotatably mounted in an engine housing (108) and arranged to rotate about a first axis of rotation (d2), and an electric drive (101, 201, 301, 401) comprising an electric machine (110) with a rotor shaft (103, 203, 303) rotatably mounted in a machine housing (117, 217, 317) parallel to the crankshaft (104) about a second axis of rotation (d1), wherein the crankshaft (104) and rotor shaft (103, 203, 303) are connected by means of a module unit (105, 205) with a module housing (118, 218, 318) which contains a gear connection (111, 211, 411) whose meshing gears (112, 113, 212, 412) are mounted on radially spaced shaft sections (114, 115, 214, 314, 414) rotatably mounted in the module housing (118, 218, 318) and are connected to each other in a rotationally interlocking manner. characterized by, that the rotor shaft (103, 203, 303) and a first of the shaft sections (114, 214, 314, 414) are coaxially connected to each other without axial play by means of a conical press fit (116, 216, 316), the first shaft section (114, 214, 314, 414) has a central opening (222) in which a preload screw (221) axially preloads the conical press fit (116, 216, 316, 416) is received. [2] Drive unit (100) according to claim 1, characterized by , that one of the shaft sections (115) is rotationally connected to a gearbox input shaft of a gearbox. [3] Drive unit (100) according to claim 1 or 2, characterized by , that the first shaft section (114, 214, 314, 414) forms a conical sleeve (220) to accommodate a conical section (219) arranged on the rotor shaft (103, 203, 303). [4] Drive unit (100) according to one of the preceding claims, characterized by, that a face gear (228) is provided between the shaft section (114, 214, 314, 414) and the rotor shaft (103, 203, 303). [5] Drive unit (100) according to any one of claims 1 to 4, characterized by , that at least one gear (112, 113, 212) and the associated shaft section (114, 115, 214, 314) are formed in one piece. [6] Drive unit (100) according to any one of claims 1 to 5, characterized by , that the first shaft section (214, 414) is axially fixed in the module housing (218) and the rotor shaft (203) is mounted with axial play in the machine housing (217). [7] Drive unit (100) according to any one of claims 1 to 5, characterized by , that the rotor shaft (303) is axially fixed in the machine housing (317) and the first shaft section (314) is mounted with axial play in the module housing (318). [8] Electric drive (101, 201, 301, 401) for a drive unit (100) according to one of claims 1 to 7, comprising an electric machine (110) with a rotor shaft (103, 203, 303) rotatably mounted about an axis of rotation (d1) in a machine housing (117, 217, 317) and a module unit (105, 205) with a module housing (118, 218, 318) which includes a gear connection (111, 211, 411) with meshing gears (112, 113, 212, 412) which are mounted on radially spaced shaft sections (114, 115, 214, 314, 414) mounted in the module housing (118, 218, 318). are, characterized by , that the rotor shaft (103, 203, 303) and a first of the shaft sections (114, 214, 314, 414) are coaxially connected to each other by means of a conical press fit (116, 216, 316) without axial play. [9] Electric drive (101, 201, 301, 401) according to claim 8, characterized by, that the electric machine (110) and the module unit (104, 205) form separate construction units which have connections to the opposite connection on a radial flange of a motor housing (108) of an internal combustion engine (102).

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