DE102022210857A1 - Electric motor-gearbox arrangement - Google Patents

Abstract

An electric motor-gearbox arrangement (100) is disclosed, wherein the electric motor-gearbox arrangement (100) has at least one gearbox with at least one gearbox input shaft (24) connected in a rotationally fixed manner to a gearbox input gear (22), a gearbox output shaft (28) connected in a rotationally fixed manner to a gearbox output gear (30), and an electric motor (10) with at least one fixed stator and a rotor (12) that can rotate relative to the stator, wherein the rotor (12) is in turn connected in a rotationally fixed manner to a motor output shaft (14) that is simultaneously designed as the gearbox input shaft (24), wherein the motor output shaft (14) is further supported on both sides of the rotor (12) by a first and a second motor bearing arrangement (16; 18) and, in its function as a gearbox input shaft (24), is additionally supported on the side of the gearbox input gear (22) facing away from the motor by at least one gearbox input bearing arrangement (26). and wherein the transmission output shaft (28) is supported on both sides by a first and second transmission output bearing arrangement (32; 34), wherein the electric motor-gearbox arrangement (100) further comprises at least one lubrication system (50), wherein the lubrication system (50) comprises a lubricant reservoir (56), a lubricant pump (52) configured to pump lubricant from the lubricant reservoir (56) to at least one lubrication point in the electric motor-gearbox arrangement (100), and one or more lubricant lines configured to conduct lubricant from the lubricant pump (52) to the at least one lubrication point.

Description

The present invention relates to an electric motor-gearbox arrangement according to the preamble of patent claim 1. Such an electric motor-gearbox arrangement is particularly suitable and preferred for use in the automotive sector, e.g. in an electric vehicle.

Due to the high speeds of electric motors, it is common, particularly in the automotive sector, to provide a gearbox between the electric motor, more precisely its output shaft, and a drive shaft of the wheels, which reduces the speed of the electric motor. Such gearboxes can be single-stage or multi-stage and usually comprise at least one gearbox input shaft that is connected in a rotationally fixed manner to a gearbox input gear and one gearbox output shaft that is connected in a rotationally fixed manner to a gearbox output gear. The gearbox input shaft is usually also the electric motor output shaft. The rotating shafts are usually supported on both sides at their respective ends by bearing arrangements, in particular roller bearing arrangements. Depending on the gear ratio, one or more transmission shafts can be present in the gearbox in addition to the gearbox input shaft and the gearbox output shaft. These are also rotatably supported by bearing arrangements that are arranged on both sides at the respective axial ends of the transmission shafts. The speed reduction takes place via appropriately dimensioned transmission gears, whereby, for example, the transmission input gear is significantly smaller and has significantly fewer teeth than the transmission output gear.

In order to ensure operation with as little friction as possible and also to reduce the temperature in the gearbox, a so-called oil circulation lubrication is also provided in the gearbox itself, in which, for example, the gearbox output gear splashes at least partially in an oil collecting pan, so that oil from the oil collecting pan is distributed as an oil mist throughout the gearbox, so that the bearing arrangements and the meshing between the gears are lubricated. This secondary oil lubrication also lubricates the gearbox input shaft bearing, but not the engine output shaft bearing, which is located outside a gearbox bell housing. In order to provide sufficient lubrication here too, the engine bearing arrangements are usually equipped with a lubricant pack designed for the entire service life of the bearing, which ensures that there is sufficient lubricating grease over the entire service life of the bearing.

However, this basic principle of lubrication reaches its limits at the already very high speeds of the electric motor, which are 15,000 revolutions per minute (rpm) and more. At even higher speeds, which are to be expected in the future, especially at speeds of up to 30,000 rpm, the motor bearing arrangement can no longer be lubricated in the usual way. In addition, running the gearbox at least partially in oil requires more energy, as splashing losses must be compensated. In the automotive sector, this in turn reduces the range, which must be avoided.

The object of the present invention is therefore to provide an electric motor-gearbox arrangement which provides improved lubrication for the motor shaft bearings even at very high speeds above 18,000 rpm, which at the same time ensures an increase in the range.

This object is achieved by an electric motor-gearbox arrangement according to patent claim 1.

In the following, an electric motor-gearbox arrangement is presented which has an electric motor with at least one fixed stator and a rotor that can rotate relative to the stator. The electric motor-gearbox arrangement also comprises a gearbox with at least one gearbox input shaft that is connected in a rotationally fixed manner to a gearbox input gear and a gearbox output shaft that is connected in a rotationally fixed manner to a gearbox output gear. Furthermore, the gearbox input shaft is simultaneously the electric motor output shaft, with the motor output shaft being supported on both sides of the rotor by a first and a second motor shaft bearing and, in its function as a gearbox input shaft, is additionally supported on the side of the gearbox input gear facing away from the motor by at least one gearbox input bearing arrangement. The gearbox output shaft is also supported on both sides, in particular at its axial ends, by a first and a second gearbox output bearing arrangement. In addition to the transmission input shaft and the transmission output shaft, the transmission can optionally have one or more transmission shafts, each with a transmission gear connected in a rotationally fixed manner, with the at least one additional transmission shaft also being supported on both sides at its axial ends by a first and a second transmission gear bearing arrangement. These bearings and engagements of the gears form the classic lubrication points in the electric motor-transmission arrangement.

To provide improved lubrication, the electric motor-gearbox arrangement further comprises at least one lubrication system with at least one lubricant reservoir, a lubricant pump and one or more lubricant lines. The lubricant pump is designed to pump lubricant from the lubricant reservoir to at least one lubrication point in the electric motor-gearbox arrangement, wherein the one or more lubrication lines are designed to guide the lubricant conveyed by the lubricant pump to the at least one lubrication point.

As mentioned above, the lubrication points can be, for example, one or more of the gearbox bearing arrangements, the motor bearing arrangements and/or the gears. Alternatively or additionally, other elements or components of the electric motor-gearbox arrangement can of course also be supplied with lubricant using the lubrication system.

The lubricant pump is preferably a mechanically driven lubricant pump. Alternatively, the lubricant pump can of course also be electrically, pneumatically, hydraulically or thermoelectrically driven. However, a mechanically driven lubricant pump does not require complex control, so that an easy-to-implement lubrication system solution can be provided.

It is particularly advantageous if the transmission output gear is coupled to a pump drive gear, in particular if it meshes with it, so that the mechanically driven lubricant pump is driven via the transmission itself. This means that existing electric motor-transmission arrangements can also be equipped with the lubrication system according to the invention. In addition, no additional control systems or control line cabling need to be provided.

According to a preferred embodiment, the lubrication system is designed to supply at least a first and a second lubrication point with lubricant, the first lubrication point being the first engine bearing arrangement and the second lubrication point being the second engine bearing arrangement. Unfortunately, engine bearing arrangements that are exposed to very high speeds have so far only been provided with a grease life pack, which can lead to insufficient lubrication. This may still be sufficient at the currently prevailing speeds of up to 15,000 rpm, but reaches its limits at higher speeds, as the existing lubricating grease is then used up too quickly. This requires frequent replacement of the entire bearing, or leads to insufficient lubrication. In order to provide a long-lasting bearing arrangement that can also be operated at even higher speeds of up to 30,000 rpm, a different type of lubrication is necessary, which is provided by the lubrication system presented here. The supply of lubricants to the engine bearing arrangements via the lubrication system also allows the bearings to be lubricated as needed and can thus significantly increase the service life of the engine bearing arrangements, even at very high speeds.

In addition to the engine bearing arrangements, the gearbox input bearing arrangement is also exposed to the risk of insufficient lubrication. Since it is operated at a very high speed just like the engine bearing arrangements, the oil mist lubrication of the usual gearbox lubrication may not be sufficient in this case either. This effect is particularly amplified by the fact that the gearbox input bearing is usually the furthest away from the oil sump, so that there is often too little oil available for lubrication here too. According to a further preferred embodiment, it is therefore provided that the lubrication system has the gearbox input bearing arrangement as a third lubrication point.

According to a further advantageous embodiment, not only the engine bearing arrangements or the transmission input bearing arrangement are integrated into the lubrication system as lubrication points, but all transmission bearing arrangements and/or gears form lubrication points for the lubrication system. This means that oil mist lubrication can be completely dispensed with, so that splashing losses are also reduced. This can increase the range of an electric vehicle, particularly in the automotive sector.

According to a further advantageous embodiment, the lubrication system further comprises at least one lubricant distribution device, in particular a lubricant distribution block and/or a valve block. Such lubricant distribution devices ensure that lubricant provided by only one pump can be distributed to many lubrication points. In addition, the various lubrication points can be lubricated as required, since lubricant is only supplied to the corresponding lubrication point when required. For example, it is possible to set the lubricant supply for the engine bearing arrangement differently than the lubricant supply to the transmission output bearing arrangement. Depending on the type of lubricant distribution device, the amount of lubricant supplied to the corresponding lubrication points can also be set via this. A metering device described below can be provided for this purpose. which is integrated into or interacts with the lubricant distribution device.

Alternatively or in addition to the lubricant distribution device, a metering device can also be assigned to at least one lubrication point. This also makes it possible to provide a certain amount of lubricant at a lubrication point independently of a lubricant distribution device. However, such a metering device can also be integrated into a lubricant distribution device or connected downstream of it, as mentioned above. It is particularly advantageous if the metering device is a metering valve, a dynamic distributor, a throttle system, an injector or a combination thereof.

According to a further advantageous embodiment, the lubricant reservoir is designed as an oil collecting pan. Such a design is particularly advantageous if a part of the transmission is to continue to be lubricated by means of oil mist lubrication, such as gears or certain transmission bearing arrangements, or the transmission as a whole continues to be operated with oil mist lubrication and only the engine bearing arrangement is supplied with lubricant via the lubrication system.

According to a further advantageous embodiment, at least one filter device for filtering the lubricant is arranged between the lubricant reservoir and the lubricant pump and/or the lubricant pump and the lubrication point. If the lubricant is returned to the lubrication system after it has been provided in or at a lubrication point, the lubricant may contain dirt particles or foreign particles that affect the condition and quality of the lubricant. In particular, the lubricant may contain abrasion particles, such as small metal particles, which inevitably arise when the electric motor-gearbox arrangement is operated. These particles can greatly increase the wear of the moving parts in the electric motor-gearbox arrangement and lead to premature failure. It is therefore necessary to remove these particles using at least one filter device so that the lubricant provided to the lubrication points is as free from contamination as possible. Such a filter device is particularly advantageous when using an oil drip pan as a lubricant reservoir.

Preferably, the filter device is arranged between the lubricant reservoir and the lubricant pump in order to also protect the lubricant pump from impairment due to foreign bodies.

It is also preferred to provide a lubricant analysis unit which uses one or more sensors to analyze one or more state variables of the lubricant, in particular temperature, viscosity, degree of contamination, moisture, composition. This can provide information about the state of the lubricant and indirectly also about the state of the lubrication point. If, for example, the sensor detects a lot of rust particles in the used lubricant, this can indicate a possible failure of the elements of the lubrication point. Likewise, an increased number of contamination particles can indicate increased wear of the elements of the lubrication point. Furthermore, the moisture content in the lubricant can be used to determine the quality or state of the lubricant.

It is also advantageous if the at least one lubricant sensor is connected to a control unit, and the control unit controls the lubricant pump depending on the at least one state variable of the lubricant in order to deliver lubricant to the lubrication point as required. It is particularly advantageous if the control unit adjusts the timing of a lubrication cycle interval and/or initiates maintenance depending on the at least one state variable of the lubricant. This can also counteract insufficient lubrication.

Of course, it is also possible to initiate lubrication depending on an engine parameter, in particular an engine speed or an engine temperature.

Further advantages and advantageous embodiments are specified in the description, the drawings and the claims. In particular, the combinations of features specified in the description and the drawings are purely exemplary, so that the features can also be present individually or in other combinations.

In the following, the invention will be described in more detail with reference to embodiments shown in the drawings. The embodiments and the combinations shown in the embodiments are purely exemplary and are not intended to define the scope of protection of the invention. This is defined solely by the appended claims.

• 1: eine schematische Darstellung eines ersten Ausführungsbeispiels der Elektromotor-Getriebe-Anordnung;
• 2: eine schematische Darstellung eines zweiten Ausführungsbeispiels der Elektromotor-Getriebe-Anordnung; und
• 3: eine schematische Darstellung eines dritten Ausführungsbeispiels der Elektromotor-Getriebe-Anordnung.

Show it:

• 1 : a schematic representation of a first embodiment of the electric motor-gearbox arrangement;
• 2 : a schematic representation of a second embodiment of the electric motor-gearbox arrangement; and
• 3 : a schematic representation of a third embodiment of the electric motor-gearbox arrangement.

In the following, identical or functionally equivalent elements are identified by the same reference symbols.

1 shows schematically an electric motor-gearbox arrangement 100 with an electric motor 10 and a gear unit 20. The electric motor 10 usually comprises a stator (not shown here) and a rotor 12 rotating in the stator, which is connected in a rotationally fixed manner to a motor output shaft 14. The motor output shaft 14 is in turn rotatably mounted via a first motor bearing arrangement 16 and a second motor bearing arrangement 18.

All bearing arrangements in the figures are shown schematically as rolling bearing arrangements, in particular ball bearings, but it is also possible to use other types of bearings, such as plain bearings or roller bearings. Of course, multi-row rolling bearings can also be used instead of the single-row rolling bearings shown here.

The transmission arrangement 20 has a transmission input gear 22 which is mounted in a rotationally fixed manner on a transmission input shaft 24. In the embodiment shown here, the transmission input shaft 24 is identical to the engine output shaft 14. The transmission input shaft 24 is also supported by a transmission input bearing arrangement 26, so that the combined engine output shaft-transmission input shaft is supported by a total of three bearing arrangements 16, 18 and 26. However, the engine bearing arrangements 16 and 18 are arranged outside a transmission bell 27, while the transmission input bearing 26 is arranged inside the transmission bell 27.

Furthermore, the embodiment shown here shows a transmission output shaft 28 to which a transmission output gear 30 is attached in a rotationally fixed manner. This transmission output shaft 28 is also rotatably mounted via transmission output bearing arrangements 32, 34 and usually transmits a torque to one or more wheels of the vehicle. One or more transmission stages can additionally be provided between the transmission input shaft 24 and the transmission output shaft 28. In the embodiments shown in the figures, a transmission stage is shown which has a transmission transmission shaft 36 which carries a first gear 38 and a second gear 40. The gear 38 with the larger diameter is designed to mesh with the transmission input gear 22, while the second transmission gear 40, which is smaller in diameter, meshes with the transmission output gear 30 with the largest diameter. This makes it possible to reduce the speed at which the electric motor 10 rotates. The gear ratio shaft 36 is also supported by two gear ratio bearing arrangements 42, 44 arranged at the axial ends of the gear shaft 36. All of these bearing arrangements 16, 18, 26, 32, 34, 42, 44 and gears 22, 30, 38, 40 must be supplied with lubricant and therefore form, among other things, the lubrication points of the electric motor-gear arrangement 100.

In order to supply the lubrication points with lubricant, a lubrication system 50 is provided which comprises a lubricant pump 52 which is designed to supply lubricant to at least one lubrication point via lubricant lines 54-1, 54-2. In the exemplary embodiments shown in the figures, the engine mounting arrangement 16, 18 in particular is supplied with lubricant via the lubrication system 50.

In the 1 In the embodiment shown, the lubrication of the lubrication points in the gearbox 20 itself is carried out via the known oil mist lubrication. For this purpose, an oil pan 56 is provided in which a gear 58 meshing with the gearbox output gear splashes and distributes the lubricant from the oil pan 56 in the gearbox bell 28.

Furthermore, the embodiment of the 1 that the lubricant pump 52 is designed as a mechanically driven pump and the gear 58 also serves as a drive gear for the mechanically driven pump 52. Furthermore, 1 that the mechanical pump 52 also removes lubricant from the oil pan 56, which thus simultaneously functions as a lubricant reservoir, from which lubricant is sucked by means of a lubricant suction line 60 and is transferred to the lubricant lines 54-1, 54-2. In the embodiment shown, the lubricant reservoir 56 is arranged together with the gear 58 in the transmission bell 27.

The pump 52 can also be arranged inside the gear housing 27, but it is advantageous to arrange it outside and to guide only a gear shaft 61, the gear 58 and the pump 52 and the lubricant suction line 60 through appropriately designed openings out of the gear housing 27 and to arrange the pump 52 outside.

In order to provide each lubrication point with a certain amount of lubricant, the lubrication system includes The system 50 also includes metering devices 62-1, 62-2 which supply the respective engine mounting arrangement 16 or 18 with a corresponding amount of lubricant.

Alternatively or additionally, a lubricant distribution device 64 (see 3 ) should be provided, which distributes and preferably also meters the lubricant to the lubrication point.

During operation of such a lubrication system 50, dirt particles or abrasion particles can get into the lubricant held in the oil pan 56. In order to reduce wear of the lubrication points caused by these particles or to avoid having to replace the lubricant very frequently, at least one filter device 66 is also provided, which is preferably arranged between the oil pan 56 and the pump 52 and ensures that undesirable elements are filtered out of the lubricant.

Furthermore, a lubricant analysis unit 68 can be provided, which uses one or more sensors to analyze one or more state variables of the lubricant, in particular temperature, viscosity, degree of contamination, moisture, composition. This can provide information about the state of the lubricant and indirectly also about the state of the lubrication point. If, for example, the sensor detects a lot of rust particles in the used lubricant, this can indicate a possible failure of the elements of the lubrication point. Likewise, an increased number of contamination particles can indicate increased wear of the elements of the lubrication point. Furthermore, the moisture content in the lubricant can be used to determine the quality or state of the lubricant.

It is also advantageous if the at least one lubricant sensor is connected to a control unit (not shown) and the control unit controls the lubricant pump 52 depending on the at least one state variable of the lubricant in order to deliver lubricant to the lubrication points as required. It is particularly advantageous if the control unit adjusts the timing of a lubrication cycle interval and/or initiates maintenance depending on the at least one state variable of the lubricant. This can also counteract insufficient lubrication.

Instead of only designing the engine mounts 18, 16 as lubrication points, it is, as in 2 shown, and to no longer lubricate the electric motor-gearbox arrangement with an oil mist lubrication, but also to lubricate it using the lubrication system 50. As is particularly evident from the embodiment of 2 As can be seen, the lubrication system not only has two lubricant supply lines 54-1, 54-2, which supply lubricant to the engine bearing assemblies 16, 18, but also further lubricant supply lines 54-3 to 54-9, which supply the various bearing assemblies 24, 32, 34, 42, 44 as well as the meshing gears 38 and 22 or 40 and 30 with lubricant. For a quantitatively adjusted distribution of lubricant to the lubrication points, further metering units or dosing units 62-1, 62-2, 62-3, 62-4, 62-5, 62-6, 62-7, 62-8, 62-9 are provided, which supply the corresponding lubrication points with lubricant in the required quantity. In the embodiment shown here, the pump 52 can also be designed as a mechanically driven lubricant pump, which is driven via the transmission output gear 30 and the pump gear 58. Analogous to the embodiment of 1 An oil collecting pan 56 can serve as a lubricant reservoir, whereby, of course, an additional filter device can be provided.

Alternatively or in addition to the metering units 62 arranged in the corresponding lubricant supply lines 54, the lubrication system 50 can also have a central distributor block 64 which, as in 3 shown, supplies lubricant to the individual lubrication points.

The oil collecting pan 56 preferably extends over the entire length of the electric motor-gearbox arrangement 100, so that the lubricant that is supplied to the individual lubrication points can drip off after passing through the lubrication points and is collected by the oil collecting pan. A complex return system can be dispensed with in this embodiment. Of course, it is also possible to provide not only lubricant supply lines 54 at the individual lubrication points, but also lubricant discharge lines that specifically transport lubricant away from the lubrication points and return it to the lubricant reservoir 56.

Overall, the proposed lubrication system enables the bearing assemblies and gears of an electric motor-gearbox arrangement to be precisely supplied with an appropriate amount of lubricant, which contributes to an increase in service life and efficiency of the system.

List of reference symbols

100

Electric motor-gearbox arrangement

10

Electric motor

12

rotor

14

Engine output shaft

16; 18

Engine mount arrangement

20

Gear unit

22

Transmission input gear

24

Gearbox input shaft

26

Gearbox input bearing arrangement

27

Gearbox bell housing

28

Gearbox output shaft

30

Transmission output gear

32; 34

Gearbox output bearing arrangement

36

Gear ratio shaft

38; 40

Gear ratio gear

42; 44

Gear ratio bearing arrangement

50

Lubrication system

52

Lubricant pump

54

Lubricant line

56

Oil pan/lubricant reservoir

58

gear

60

Lubricant intake line

61

Gear shaft

62

Dosing device

64

Lubricant distribution device

66

Filter device

68

Analysis unit

Claims (13)

Electric motor-gearbox arrangement (100), wherein the electric motor-gearbox arrangement (100) has at least one gearbox with at least one gearbox input shaft (24) connected in a rotationally fixed manner to a gearbox input gear (22), a gearbox output shaft (28) connected in a rotationally fixed manner to a gearbox output gear (30), and an electric motor (10) with at least one fixed stator and a rotor (12) that can rotate relative to the stator, wherein the rotor (12) is in turn connected in a rotationally fixed manner to a motor output shaft (14) that is simultaneously designed as the gearbox input shaft (24), wherein the motor output shaft (14) is further supported on both sides of the rotor (12) by a first and a second motor bearing arrangement (16; 18) and, in its function as a gearbox input shaft (24), is additionally supported on the side of the gearbox input gear (22) facing away from the motor by at least one gearbox input bearing arrangement (26), and wherein the Transmission output shaft (28) are supported on both sides by a first and second transmission output bearing arrangement (32; 34), characterized in that the electric motor-gearbox arrangement (100) further comprises at least one lubrication system (50), wherein the lubrication system (50) comprises a lubricant reservoir (56), a lubricant pump (52) which is designed to pump lubricant from the lubricant reservoir (56) to at least one lubrication point in the electric motor-gearbox arrangement (100), and one or more lubricant lines which are designed to conduct lubricant from the lubricant pump (52) to the at least one lubrication point. Electric motor-gearbox arrangement (100) according to Claim 1 , wherein the transmission further comprises at least one transmission gearwheel rotationally fixedly connected to at least one transmission shaft, wherein the at least one transmission shaft is supported on both sides by a first and a second transmission bearing arrangement. Electric motor-gearbox arrangement (100) according to Claim 1 or 2 , wherein the lubricant pump (52) is a mechanically driven lubricant pump (52). Electric motor-gearbox arrangement (100) according to Claim 3 , wherein the transmission output gear (30) is coupled to a pump drive gear which mechanically drives the lubricant pump (52). Electric motor-gearbox arrangement (100) according to one of the preceding claims, wherein the lubrication system (50) has at least a first and a second lubrication point, wherein the first lubrication point is the first motor bearing arrangement (16; 18) and the second lubrication point is the second motor bearing arrangement (16; 18). Electric motor-gearbox arrangement (100) according to one of the preceding claims, wherein the lubrication system (50) has at least a third lubrication point, the third lubrication point being the transmission input bearing arrangement (26). Electric motor-gearbox arrangement (100) according to one of the preceding claims, wherein all gear bearing arrangements form lubrication points for the lubrication system (50). Electric motor-gearbox arrangement (100) according to one of the preceding claims, wherein the lubrication system (50) further comprises at least one lubricant distribution device (64), in particular a lubricant distribution block and/or a valve block. Electric motor-gearbox arrangement (100) according to one of the preceding claims, wherein a metering device (62) is assigned to at least one lubrication point. Electric motor-gearbox arrangement (100) according to one of the preceding claims, wherein the metering device (62) is a metering valve, a dynamic distributor, a throttle system, an injector or a combination thereof. Electric motor-gearbox arrangement (100) according to one of the preceding claims, wherein the lubricant reservoir (56) is an oil collecting pan. Electric motor-gearbox arrangement (100) according to one of the preceding claims, wherein a filter device (66) for filtering the lubricant is arranged between the lubricant reservoir (56) and the lubricant pump (52) and/or the lubricant pump (52) and the lubrication point. Electric motor-gearbox arrangement (100) according to one of the preceding claims, wherein a control device is further provided which is designed to actuate the lubricant pump (52), wherein the control device is preferably designed to actuate the lubricant pump (52) depending on an engine characteristic variable, in particular an engine speed, an engine temperature.

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