Electric machine arrangement, motor vehicle gearbox and method for producing an electric machine arrangement

Abstract

An electric machine arrangement for a motor vehicle drivetrain, having a machine housing which can be fixed to a drivetrain housing, a stator which is fixed relative to the machine housing, a rotor which is mounted, concentrically with respect to the stator, within the machine housing and which has a rotor axis, wherein an air gap is defined between the stator and the rotor. Here, the rotor has a rotary bearing section which is mounted, with a radial clearance, rotatably relative to a housing bearing section of the machine housing, wherein the radial clearance is smaller than the air gap.

Claims

1. An electric machine arrangement for a motor vehicle drivetrain, having: a machine housing which can be fixed to a drivetrain housing; a stator which is fixed relative to the machine housing; and a rotor which is mounted, concentrically with respect to the stator, within the machine housing and which has a rotor axis; wherein an air gap is defined between the stator and the rotor; wherein the rotor has a rotary bearing section which is mounted, with a radial clearance, rotatably relative to a housing bearing section of the machine housing, wherein the radial clearance is smaller than the air gap; wherein the rotor has a first axial rotor end section which is mounted, by way of a first rotary bearing, rotatably relative to the machine housing, wherein the first rotary bearing is fixed to a first bearing seat of a first wall section of the machine housing, and wherein the first wall section of the machine housing is also designed such that radial forces introduced by the rotor into the first wall section via the first rotary bearing can be transmitted into the drivetrain housing when the machine housing is fixed to the drivetrain housing; and wherein the first wall section has a ring-shaped web which can be inserted into a ring-shaped web receptacle of the drivetrain housing.

2. The electric machine arrangement according to claim 1, wherein the rotor has a second axial rotor end section which extends at least partially out of the machine housing in an axial direction and is designed to be mounted, by way of a second rotary bearing, rotatably relative to the drivetrain housing.

3. The electric machine arrangement according to claim 2, wherein a toothed wheel is mounted on the second axial rotor end section.

4. The electric machine arrangement according to claim 3, wherein the toothed wheel is arranged in the axial direction between the machine housing and a rotary bearing region of the second rotor end section.

5. The electric machine arrangement according to claim 2, wherein the second axial rotor end section extends out of a second wall section of the machine housing, the second wall section at an opposite end of the machine housing from the first wall section, the machine housing having a machine housing flange configured to secure the opposite end of the machine housing to the drivetrain housing.

6. The electric machine arrangement according to claim 5, wherein the machine housing flange extends in a common plane with the second wall section of the machine housing.

7. The electric machine arrangement according to claim 1, wherein the ring-shaped web is arranged so as to overlap, or be adjacent to, the first bearing seat of the first wall section of the machine housing in an axial direction.

8. The electric machine arrangement according to claim 1, wherein the machine housing has a second bearing seat for a secondary shaft which is arranged parallel and offset with respect to a longitudinal axis of the rotor.

9. The electric machine arrangement according to claim 8, wherein the second bearing seat is formed on a second wall section of the machine housing, wherein the housing bearing section is formed in the second wall section.

10. The electric machine arrangement according to claim 8, wherein a first toothed wheel is mounted on the second rotor end section, wherein, on the secondary shaft, there is mounted a second toothed wheel which meshes with a first toothed wheel.

11. The electric machine arrangement according to claim 1, wherein the stator has a lamination pack which is inserted into a cylindrical section of the machine housing, wherein at least one cooling duct is formed between the lamination pack and the cylindrical section.

12. The electric machine arrangement according to claim 11, wherein, between the lamination pack and the cylindrical section, there is formed a multiplicity of cooling ducts, wherein a distributor device for supplying cooling fluid to the cooling ducts is formed in the region of a second wall section of the machine housing.

13. The electric machine arrangement according to claim 1, wherein at least a part of the machine housing is sealed off with respect to the interior of the drive housing.

14. A method for producing an electric machine arrangement, having the steps: providing a machine housing which has a housing bearing section; providing a stator and fixing the stator to the machine housing; providing a rotor which has two axial rotor end sections; and axially inserting the rotor into the stator, wherein an air gap is formed between the stator and the rotor, and wherein one of the rotor end sections is inserted into the housing bearing section so as to be mounted, with a radial clearance, rotatably relative to the housing bearing section of the machine housing, wherein the radial clearance is smaller than the air gap; wherein the rotor has a first axial rotor end section which is mounted, by way of a first rotary bearing, rotatably relative to the machine housing, wherein the first rotary bearing is fixed to a first bearing seat of a first wall section of the machine housing, and wherein the first wall section of the machine housing is also designed such that radial forces introduced by the rotor into the first wall section via the first rotary bearing can be transmitted into the drivetrain housing when the machine housing is fixed to the drivetrain housing; and wherein the first wall section has a ring-shaped web which can be inserted into a ring-shaped web receptacle of the drivetrain housing.

15. The method according to claim 14, wherein the rotor has a second axial rotor end section opposite the first axial rotor end section, the second axial rotor end section extending at least partially out of the machine housing in an axial direction and is designed to be mounted, by way of a second rotary bearing, rotatably relative to the drivetrain housing; and wherein the second axial rotor end section extends out of a second wall section of the machine housing, the second wall section at an opposite end of the machine housing from the first wall section, the machine housing having a machine housing flange configured to secure the opposite end of the machine housing to the drivetrain housing.

16. The method according to claim 15, wherein the machine housing flange extends in a common plane with the second wall section of the machine housing.

Description

DRAWINGS

(1) Exemplary embodiments of the invention are illustrated in the drawing and will be discussed in more detail in the following description. In the drawing:

(2) FIG. 1 is a schematic illustration of a motor vehicle drivetrain having a motor vehicle gearbox according to the invention and having an electric machine arrangement according to the invention installed therein;

(3) FIG. 2 is a schematic illustration of a further drivetrain having an electric machine arrangement;

(4) FIG. 3 is a further illustration of a drivetrain having an electric machine arrangement, in a partial longitudinal sectional illustration;

(5) FIG. 4 shows a schematic, perspective exterior view of a further embodiment of an electric machine arrangement;

(6) FIG. 5 shows a further perspective view of the electric machine arrangement of FIG. 4; and

(7) FIG. 6 is a schematic, perspective and partially cut-away illustration of an electric machine arrangement of the type according to an embodiment of the invention.

DESCRIPTION

(8) In FIG. 1, a drivetrain for a motor vehicle is illustrated schematically and denoted generally by 10.

(9) The drivetrain 10 has a primary drive engine 12, for example in the form of an internal combustion engine. The drivetrain 10 also comprises a clutch arrangement 14 which is connected at the input side to the drive engine 12 and at the output side to a gearbox arrangement 16. An output of the gearbox arrangement 16 is connected to a differential 18 by means of which drive power can be distributed to driven wheels 20L, 20R.

(10) The gearbox arrangement 16 comprises a multi-stage gearbox 24 which, in the present case, is designed as a countershaft-type gearbox of spur wheel type of construction. The gearbox 24 has a gearbox housing 26 on which an input shaft arrangement 28 is mounted. The input shaft arrangement 28 is connected to the clutch arrangement 14.

(11) Furthermore, on the gearbox housing 26, there is mounted an output shaft arrangement 30 which is connected to the differential 18. A multiplicity of gear wheel sets 32 (of which only one is illustrated in FIG. 1 for the sake of clarity) connect the input shaft arrangement 28 to the output shaft arrangement 30. The gear wheel sets 32 can be shifted by way of respective shift clutches 34. More precisely, each gear wheel set comprises a fixed wheel and a loose wheel which mesh with one another. The loose wheel can, by way of an associated shift clutch 34, be connected rotationally conjointly to a shaft on which the loose wheel is rotatably mounted.

(12) The gearbox 24 may be in the form of a manual gearbox, though may also be an automated gearbox. In particular, the gearbox 24 may be a dual-clutch gearbox. In this case, the clutch arrangement 14 comprises two friction clutches, and the input shaft arrangement 28 comprises two input shafts, as is known per se in the prior art. In the case of dual-clutch gearboxes, gear changes are performed by way of overlapping of the actuation of the clutches of the clutch arrangement 14, such that gear changes can be performed substantially without a loss of traction force.

(13) In the present case, the drivetrain 10 comprises an electric machine arrangement 40, wherein the electric machine arrangement 40 can be operated as a secondary drive motor, though can also be operated as a generator in order, for example, to charge a battery (not illustrated in any more detail) of the drivetrain 10.

(14) The electric machine arrangement 40 comprises an electric machine 42 and a machine housing 44. The electric machine 42 has a stator 46 which is fixed in the machine housing 44. The electric machine 42 and the stator 46 thereof are arranged coaxially with respect to a machine or rotor axis 48. The machine or rotor axis 48 is formed parallel to the input shaft arrangement 28 and/or to the output shaft arrangement 30.

(15) The electric machine 42 furthermore has a rotor 50 which, in the present case, is arranged coaxially within the stator 46 and has a drive shaft 52 oriented coaxially with respect to the rotor axis 48. On the drive shaft 52 there is fixed a drive pinion 54. The drive pinion 54 meshes with an intermediate wheel 56. The intermediate wheel 56 in turn likewise meshes with a loose wheel 58 of a gear wheel set 32 of the gearbox 24. If the associated shift clutch 34 is closed, it is consequently possible for drive power to be transmitted from the electric machine 42 to the output of the gearbox 24 via the spur wheel set composed of drive pinion 54, intermediate wheel 56 and loose wheel 58.

(16) Here, the electric machine 42 may in particular be connected to one of two sub-gearboxes of the gearbox 24 if the latter is in the form of a dual-clutch gearbox, in particular to the sub-gearbox assigned to the even-numbered gear stages and/or with a reverse gear stage.

(17) The electric machine 42 may be assigned, via a fixed transmission ratio stage, to an input shaft of the gearbox 24, in particular to the input shaft of one of the sub-gearboxes of the gearbox 24. The fixed transmission ratio stage may be formed by suitable toothed wheels; loose wheels of a gear stage toothing are also possible here. A wheel set 32 to which the electric machine 42 can be connected may be assigned for example to a mid-range gear stage, for example gear stage 4. Alternatively, the loose wheel 58 may also be assigned to the gear stage 2, or else to the gear stage 6, or to an even higher gear stage.

(18) It is however also conceivable for the electric machine 42 to be assigned to the other sub-gearbox, in this case preferably likewise to a mid-range gear stage, for example to gear stage 3 or gear stage 5. In general, it is also conceivable for the electric machine 42 to be connected to the output of the gearbox 24, that is to say for the electric machine 42 to be assigned to the drive output of the gearbox 24, that is to say such that the rotational speed of said electric machine is proportional to the travelling speed.

(19) It is also schematically illustrated in FIG. 1 that there is an air gap 60 between the rotor 50 and the stator 46. The rotor 50 may comprise a multiplicity of permanent magnets on its outer circumference. The stator is, in a conventional manner, equipped with electrical winding terminals for the supply of electrical power to, or extraction of electrical power from, the electric machine 42. The electric machine 42 may generally be any type of electric machine, for example an asynchronous machine, a permanently excited or externally excited synchronous machine, a reluctance machine etc.

(20) The machine housing 44 comprises a cylindrical section 64 which is arranged coaxially with respect to the electric machine 42 and which is for example fixed around the outside of the stator 46. The machine housing 44 furthermore has a first wall section 66, which is arranged on that side of the electric machine 42 which is situated axially opposite the drive shaft 52, and a second wall section 68, which faces toward the drive shaft 52.

(21) The first wall section 66 and the cylindrical section 64 may be formed integrally with one another, for example from a thin material such as sheet metal. The second wall section 68 may be formed as a bearing plate which is designed for accommodating radial forces and for transmitting such radial forces to the gearbox housing 26. The second wall section 68 in the form of a bearing plate of said type may, for this purpose, be connected to the gearbox housing 26.

(22) The gearbox housing 26 has a first housing wall 70 which is arranged approximately parallel to the first wall section 66 of the machine housing 44 and adjacent thereto. Furthermore, the gearbox housing 26 comprises a second housing wall 72 which is adjacent to the second wall section 68 of the machine housing 44.

(23) The first wall section 66 of the machine housing 44 has a ring-shaped web 74 which is oriented coaxially with respect to the rotor axis 48. The first housing wall 70 has a ring-shaped web receptacle 76 into which the ring-shaped web 74 can be inserted axially such that radial forces introduced into the ring-shaped web 74 can be transmitted to the gearbox housing 26.

(24) The machine housing 44 furthermore has, in the region of the second wall section 68, a machine housing flange 78 which is connected by way of schematically indicated connecting means to a gearbox housing flange 80 of the gearbox housing 26.

(25) In other words, the electric machine arrangement 40 can be inserted in an axial direction into the gearbox housing 26 until the ring-shaped web 74 is received in the ring-shaped web receptacle 76, and the machine housing flange 78 can be screwed, or fastened in some other way, to the gearbox housing flange 80.

(26) The gearbox housing 26 may furthermore additionally have a machine housing receptacle 82 as schematically indicated in FIG. 1. The gearbox housing 26 however need not surround the machine housing 44 over the full circumference.

(27) The rotor 50 has a first axial rotor end section 86 and an oppositely situated second axial rotor end section 88.

(28) The first axial rotor end section 86 is mounted rotatably relative to the machine housing 44 by way of a first rotary bearing 90 which is inserted into a first bearing seat 92 of the first wall section 66 of the machine housing 44.

(29) The bearing seat 92 is preferably provided so as to axially overlap the ring-shaped web 74 in order that radial forces introduced into the first rotary bearing 90 can be introduced by said bearing seat into the gearbox housing. The ring-shaped web 74 and the first bearing seat 92 may however also be adjacent to one another in the axial direction such that the machine housing 44 initially transmits radially introduced forces axially, before said forces are then transmitted via the ring-shaped web 74 into the gearbox housing 26.

(30) The second axial rotor end section 88 has a rotary bearing section 98 which is mounted, with a radial clearance 99, rotatably relative to a housing bearing section 96 and rotatably relative to the machine housing 44. The interaction between rotor bearing section 98 and housing bearing section 96 serves for the centring of the rotor 50 in said region, that is to say in the region of the second axial rotor end section 88. Here, the radial clearance 99 is considerably smaller than the radial air gap 60 between rotor 50 and stator 46.

(31) In this way, it is possible to prevent a situation in which, in a transportation state, when the machine arrangement 40 has not yet been installed into the gearbox housing 26, the rotor 50 makes contact with the stator 46, for example owing to the fact that the rotor 50 comprises strong permanent magnets on its outer circumference.

(32) The second axial rotor end section 88 is furthermore mounted rotatably relative to the second housing wall 72 of the gearbox housing 26 by way of a second rotary bearing 100. The installation of the second housing wall 72 and of the bearing 100 in relation to the second axial rotor end section 88 is preferably performed only after the electric machine arrangement 40 has been installed in the gearbox housing 26.

(33) The drive pinion 54 is arranged in an axial direction between the rotor bearing section 98 and the second rotary bearing 100. The first rotary bearing 90 and the second rotary bearing 100 may each be in the form of rolling bearings, in particular ball bearings.

(34) If the drive pinion 54 is helically toothed, the second rotary bearing 100 preferably also serves for accommodating axial forces that arise from the tooth meshing action.

(35) The intermediate wheel 56 is fixed to a secondary shaft 104. The secondary shaft 104 is mounted rotatably relative to the second wall section 68 of the machine housing 44 by way of a first secondary shaft bearing 106. For this purpose, the second wall section 68 has a second bearing seat 108 which is formed on the second wall section 68 so as to be eccentrically offset relative to the rotor axis 48.

(36) The secondary shaft 104 is, on the axially opposite side of the intermediate wheel 56, mounted rotatably relative to the gearbox housing 26, in particular relative to the second housing wall 72, by way of a second secondary shaft bearing 110. For this purpose, a suitable bearing seat is preferably provided on the second housing wall 72. The first secondary shaft bearing 106 and the second secondary shaft bearing 110 may each be in the form of rolling bearings, in particular ball bearings, though may also be in the form of plain bearings.

(37) The secondary shaft 104 with the intermediate wheel 56 fixed thereto may be provided with the preassembled electric machine arrangement 40, in such a way that the first secondary shaft bearing 106 is already inserted into the second wall section 68 and the secondary shaft 104 is inserted into said first secondary shaft bearing, such that the intermediate wheel 56 meshes with the drive pinion 54. The installation of the secondary shaft 104 with its bearings 106, 110 however preferably takes place only after the electric machine arrangement 40 has been installed on the gearbox housing 26.

(38) The following figures illustrate further embodiments of drivetrains and electric machine arrangements which, in terms of construction and function, correspond to the drivetrain of FIG. 1 and/or to the electric machine arrangement of FIG. 1. Identical elements are therefore denoted by the same reference signs. Substantially the differences will be discussed below.

(39) FIG. 2 shows a part of the drivetrain 10 with an electric machine arrangement 14, wherein the machine housing 44 is formed by a solid second wall section 68 in the form of a bearing plate which is dimensioned such that, for example, a non-supported bearing seat for the secondary shaft 104 may also be formed therein, even though this is not illustrated in FIG. 2. The cylindrical section 64 and the first wall section 66 are, by contrast, formed as thin sections and may be formed integrally with one another. For example, the housing part which forms the cylindrical section 64 and the first wall section 66 may be formed from a sheet-metal pot.

(40) It can be seen that the first rotary bearing 90 overlaps the ring-shaped web receptacle 76 in an axial direction in order that said first rotary bearing can introduce radial forces by the ring-shaped web 74 as directly as possible into the first housing wall 70 of the gearbox housing 26.

(41) It is also shown in FIG. 2 that, for the second rotary bearing 100, a bearing seat 112 is formed in the second housing wall 72. It can also be seen in FIG. 2 that, in the second wall section 68 of the machine housing 44, there may be formed a fluid port 114 via which cooling fluid can be supplied. The fluid port 114 may be connected, in the interior of the machine housing 44, to a distributor device 116 which is formed for example in the manner of a ring-shaped duct. Fluid that is introduced can be conducted via openings in the ring-shaped duct 116 onto the adjacent winding heads 118 of windings of the stator 46 in order to cool these, because the winding heads 118 are subjected to the greatest thermal load during the operation of the electric machine 42.

(42) The stator 46 furthermore has a lamination pack 120 which bears directly against the inner circumference of the cylindrical section 64. Here, a multiplicity of cooling ducts 122 is formed on the lamination pack 120 in a circumferentially distributed manner, which cooling ducts extend in an axial direction such that fluid introduced via the fluid port 114 can flow through the cooling ducts 122 in order to cool the stator 46. At the axial end adjacent to the first wall section 66, the fluid can emerge from the cooling ducts and be conducted to the winding heads 118 provided there, in order to cool these also.

(43) The cooling concept may correspond to the cooling concept disclosed in documents DE 10 2012 022 452 A1 and 10 2012 022 453 A1, the entire disclosure of which is hereby referred to.

(44) FIG. 3 shows a further embodiment of a drivetrain 10, with a detail view of a second housing wall 72 and of a second wall section 68.

(45) It can be seen that the second axial rotor end section 88, which extends out of the second wall section 68 in an axial direction, is in the form of a hollow shaft and is connected at its axial end to a covering cap 124 in order to be able to conduct the cooling fluid, which is supplied via an axial duct 126 in the rotor end section 66, to the second rotary bearing 100. The covering cap 124 may also be closed, even though this is not illustrated in FIG. 3.

(46) FIGS. 4 to 6 show a further embodiment of an electric machine arrangement. Firstly, FIG. 4 shows that the machine housing flange 78 may have a multiplicity of radially protruding eyelets in which there are formed respective bores 130 for the leadthrough of screws or the like.

(47) It can also be seen that, on the second wall section 68, there is formed an electrical plug connector by way of which the stator windings can be electrically contacted.

(48) Furthermore, in FIG. 4, it is possible to see the meshing of the drive pinion 54 and of the intermediate wheel 56, which is mounted rotatably relative to the second wall section 68 by way of the secondary shaft 104 and the first secondary shaft bearing 106 (not shown).

(49) FIG. 5 shows the electric machine arrangement 40 of FIG. 4 from the rear side, wherein it can be seen that the first wall section 66 shown here duly has a ring-shaped web 74 but may otherwise be equipped with apertures and recesses in order to save weight.

(50) FIG. 6 shows a similar view to FIG. 4, but with a section of the machine housing 44 having been cut away. It can be seen here that the stator 56 has a lamination pack 120 with a multiplicity of axial cooling ducts 122 formed between the cylindrical section 64 and the lamination pack 120. It can also be seen that the distributor device 116 may be in the form of a ring-shaped duct which is connected to the second wall section 68 and via which fluid can be conducted to the adjacent winding head 118.