Configuration and vehicle including an electromechanical machine and a gearbox

Abstract

To achieve service-life prolongation of a radial shaft seal.SOLUTION: An arrangement has an electric machine (2), a gearbox (3), a shaft (9) that connects the electric machine (2) to the gearbox (3) and has an axial blind hole (18), a coolant introducing element (21), and a coolant guiding element (22). The shaft (9) is disposed to rotate around the coolant guiding element (22). The arrangement further comprises a first bearing (12) disposed between a rotor (10) and a gear (11), a second bearing (14) disposed in a housing structure (15), a third bearing (16) disposed in a non-drive end shield (17) of a housing (6) of the electric machine (2), and a radial shaft seal (32) that is disposed between the first bearing (12) and the rotor (10) and attached to the shaft (9). The radial shaft seal (32) is cooled with a coolant.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a configuration including an electric machine and a gearbox. The present invention also relates to a vehicle.

Background Art

[0002] A configuration including an electric machine and a gearbox needs to meet high requirements regarding power density, especially when used as an integrated drive system for an electric vehicle. As a result, each component of the configuration is designed to operate near its thermal limit. Regarding the gearbox, the temperature of the lubricating oil collected in the oil sump should typically not exceed the maximum rated temperature of 120°C to 140°C over a given period. Otherwise, the heat generated by the rolling contact of the gearbox may not be sufficiently dissipated, the lubricating film may break down, and wear may increase. Thereby, the gearbox may be heated and damaged.

[0003] Adversely, the heat loss of the rotor heats the shaft connecting the electric machine to the gearbox. The shaft transfers heat to the gearbox via seals and bearings.

[0004] WO2016 / 050534A1 discloses an electric machine including a rotor having a shaft with a shaft hole and a flow guide element extending into the shaft hole such that a coolant can flow through the shaft hole. The coolant is supplied to the flow guide element via a coolant inlet.

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of the present invention is to provide an improved configuration including an electric machine and a gearbox, and in particular to enable improved heat dissipation from the gearbox.

Means for Solving the Problems

[0006] According to the present invention, the above object is solved by a configuration including an electromechanical machine, a gearbox, a shaft that connects the electromechanical machine to the gearbox and has an axial blind hole extending from the mechanical side end of the shaft to the gearbox, a coolant introduction element configured to supply coolant into the hole, and a coolant guiding element that extends from the mechanical side end into the gearbox inside the hole and defines a flow path for the introduced coolant.

[0007] The present invention is based on the idea of extending the liquid cooling of the shaft to the gearbox. When the heat generated by the rotor is transmitted to the gearbox by the shaft, advantageously, by cooling the shaft between the mechanical side end and the gearbox, the heat is effectively dissipated at the position where the heat enters the gearbox. Furthermore, the heat generated by the rolling contact of the gears in the gearbox is dissipated by the coolant. Here, the lubricant film that wets the shaft is effectively cooled through the shaft, forming a thermal connection of the entire lubricant in the gearbox.

[0008] Typically, the electromechanical machine and the gearbox are arranged in the same housing. Thus, this configuration can particularly realize an integrated drive system for a vehicle. Preferably, the electromechanical machine operates within a non-overloaded operating range at a rotational speed of 12,000 min -1 , preferably 15,000 min -1 , more preferably 20,000 min -1 . The above rotational speed makes it possible to achieve the high power density required for the latest automotive drive systems. In particular, the electromechanical machine is a permanent magnet synchronous machine. The shaft can be regarded as the main shaft of this configuration. The rotor and / or the gear may be attached to the shaft so as to be torque-resistant. Typically, the coolant contains water and / or glycol. The mechanical side end can be regarded as the non-driven end (NDE) of the shaft.

[0009] Preferably, the hole is realized by a shaft having a through hole axially closed by a closing element. The closing element may comprise a plug, a stud or a nut. The shaft may be formed by a tubular non-machined material or may be formed by drilling a through hole.

[0010] Here, within the drive end shield of the housing of the electromechanical machine, a first bearing disposed between the rotor and the gear, a second bearing disposed within the housing structure of the housing of the gearbox, a third bearing disposed within the non-drive end shield of the housing of the electromechanical machine, and a radial shaft seal disposed between the first bearing and the rotor and attached to the shaft, and the radial shaft seal is cooled by the coolant. Thus, in order to avoid the coolant coming into contact with the lubricant within the gearbox, sealing means are disposed on the closing element.

[0011] Advantageously, the blind end of the shaft has deflecting means configured to swirl the coolant. When the coolant flows towards the deflecting means, a turbulent flow that improves heat dissipation is generated. The deflecting means has a hole side surface that is non-perpendicular to the axis of rotation of the shaft. In other words, the normal of the hole side surface and the axis of rotation may form an angle greater than 0°, preferably greater than at least 1°, more preferably greater than at least 5°.

[0012] Preferably, the deflecting means is realized by a closing element. Thus, the region of the closing element facing the machine side end may be formed to have a non-perpendicular hole side surface.

[0013] The coolant guiding element may be configured such that the shaft rotates around the coolant guiding element. However, it is also possible for the coolant guiding element to rotate with the rotor, for example by being arranged to be torque-resistant with respect to the rotor. Here, the coolant guiding element may be rotatable with respect to the coolant introducing element.

[0014] Regarding the configuration of the present invention, it is preferable that the coolant guiding element separates the hole into an inner region and an outer region, and one of the regions is configured to realize a flow path. The coolant guiding element may have a closed cross-section surrounding the inner region. In particular, the coolant guiding element is a pipe or a tube. Therefore, the coolant guiding element can be regarded as a cooling lance.

[0015] Preferably, the inner region realizes a flow path. Here, the coolant flows through the inside of the coolant guiding element up to the blind end, and then flows out from the inner region and contacts the shaft. After flowing out from the inner region, the coolant flows back to the machine side end while contacting the shaft. Alternatively, the coolant is guided to flow through the outer region and through the hole, and then flow back to the machine side end through the inner region.

[0016] The coolant guiding element may further have an outer shape that extends in the axial direction of the shaft and projects into the outer region and is open in the circumferential direction, particularly a spiral outer shape. Therefore, when flowing back to the machine side end, turbulence is generated by the outer shape. Furthermore, since the outer shape does not follow the rotation of the shaft, the rotation of the shaft generates an axial movement of the coolant.

[0017] The coolant guiding element and the outer shape can be formed as a single part, but preferably the outer shape is realized by an outer shape element arranged around the coolant guiding element. The outer shape element may be a wire or a ribbon, and / or may be formed of a polymer and / or a metal. Preferably, the outer shape element is a molded part pressed onto or wound around the coolant guiding element. The outer shape element may be fixed by press-fitting. Alternatively, the outer shape element may be realized by molding on the coolant guiding element.

[0018] This configuration comprises a radial shaft seal disposed between a rotor attached to a shaft and a gear, and the radial shaft seal is cooled by a coolant. Typically, the radial shaft seal prevents lubricant from entering the air gap of the electromechanical machine. Therefore, the radial shaft seal is preferably disposed between a bearing and a rotor disposed within the drive end shield (DE shield) of the electromechanical machine. Since the radial shaft seal can be subject to high wear during overheating, the cooling method of the present invention enables the radial shaft seal to have a longer lifespan.

[0019] Furthermore, the present invention relates to a vehicle comprising the configuration of the present invention and configured to drive the vehicle.

[0020] All descriptions regarding the configuration of the present invention are equally applicable to the vehicle of the present invention, and thus the above-described advantages of the configuration of the present invention are equally achieved.

[0021] Further details and advantages of the present invention are disclosed below with reference to the schematic drawings.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0023] FIG. 1 is a perspective view of an embodiment of a configuration 1 comprising an electromechanical machine 2 and a gearbox 3. Configuration 1 is an integrated drive system for a vehicle with a high power density, and the electromechanical machine 2 is operable at a rotational speed of up to 22,000 min -1 within the non-overloading operating range.

[0024] Configuration 1 further includes an inverter 4 configured to electrically supply the electromechanical machine 2. The electromechanical machine 2, the gearbox 3, and the inverter 4 have a common housing 5 with the machine housing 6 and the gearbox housing 7. The housing 5 may be realized by the housing of one part where the machine housing 6 and the gearbox housing 7 are corresponding housing areas, or by the housings of two or more parts.

[0025] The gearbox 3 has two side shafts 8, and in FIG. 1, one side shaft is hidden. The side shafts 8 are connected by the differential gear of the gearbox 3 and can be attached to the wheel hubs of the vehicle.

[0026] FIG. 2 is a cross-sectional view of Configuration 1 along cross-section II shown in FIG. 1. Configuration 1 includes a shaft 9 attached to the rotor 10 of the electromechanical machine 2 and the gear 11 of the gearbox 3. Thus, the shaft 9 directly connects the rotor 10 and the gear 11 and can be regarded as the main shaft of Configuration 1.

[0027] Configuration 1 further includes a first bearing 12 disposed between the rotor 10 and the gear 11 at the drive end shield 13 (DE shield) of the machine housing 6, a second bearing 14 disposed within the housing structure 15 of the gearbox housing 7, and a third bearing 16 disposed at the non-drive end shield 17 (NDE shield) of the machine housing 6.

[0028] The shaft 9 includes an axially blind hole 18 extending from the machine side end 19 of the shaft 9 into the gearbox 3 to the region of the shaft 9 where the second bearing 14 is disposed. The hole 18 is realized by a shaft 9 having a through hole axially closed by a closing element 20. The closing element 20 is a nut and also attaches the second bearing 14 and the gear 11 of the gearbox 3. Alternatively, the closing element is a plug or a stud. The shaft 9 may be formed by a tubular non-machined material having a through hole. Alternatively, the through hole may be drilled in the shaft 9.

[0029] Furthermore, Configuration 1 includes a coolant introduction element 21 arranged at the machine-side end 19 and configured to introduce and supply a coolant, such as a mixture of water and glycol, into the hole 18. The coolant introduction element 21 may be configured as described in WO2016 / 050534A1. When the coolant enters the hole 18, it is guided by the coolant guiding element 22 of Configuration 1. The coolant guiding element 22 is arranged such that the shaft 9 rotates around the coolant guiding element 22. That is, the coolant guiding element 22 and the shaft 9 are not connected to each other in a torque-resistant manner.

[0030] The coolant guiding element 22 extends within the hole 18 along a flow path 23 for the coolant from the machine-side end 19 into the gearbox 3. The coolant guiding element 22 extends within the hole 18 to a free blind end 24. The coolant guiding element 22 is tubular and arranged coaxially with the hole 18. Thus, the coolant guiding element 22 separates the hole 18 into an inner region 25 and an outer region 26, and the inner region 25 realizes the flow path 23.

[0031] When the coolant is supplied and introduced into the coolant guiding element 22 by the coolant introduction element 21, the coolant flows out of the coolant guiding element 22 at the blind end 24. Thereby, it comes into contact with the deflecting means 27 arranged at the blind end 24. The deflecting means 27 is configured to swirl the coolant, and as a result, a turbulent flow is generated so that the cooling effect is improved. And the hole side surface 28 of the deflecting means 27 is not perpendicular to the rotation axis 29 of the shaft 9. The deflecting means 27 is realized by the closing element 20. Thus, the nut forming the closing element 20 has an inclined surface 28 on its hole side. After swirling, the coolant flows back to the machine-side end 19. And the coolant introduction element 21 has an outlet. Furthermore, Configuration 1 includes a pump (not shown) configured to pump the coolant along a closed cooling circuit.

[0032] Furthermore, the coolant guiding element 22 has an axially extending and circumferentially open, i.e., spiral-shaped outer profile 30 that projects into the outer region 26 along the axis of the shaft 9. The outer profile 30 is realized by an outer profile element 31 arranged around the coolant guiding element 22. Thus, when the shaft 9 rotates, the coolant guiding element 22 remains stationary, and the reverse flow of the coolant is increased by the outer profile 30 having an effect similar to that of an axial pump.

[0033] Figure 3 is a cross-sectional view of the coolant guiding element 22. As can be seen from the figure, the outer profile element 31 is a ribbon pressed onto or wound around the coolant guiding element 22. The outer profile element 31 is formed of a polymer as a molded part. Alternatively, the outer profile element 31 is formed of metal, or a combination of polymer and metal. The outer profile element 31 is press-fitted at both ends of the coolant guiding element 22. Although depicted as a ribbon in Figure 3, the coolant guiding element 22 may alternatively be a wire.

[0034] In this way, Configuration 1 enables the coolant to be conveyed to the hole 18 along the cooling flow path 23. When flowing out of the cooling flow path 23 at the blind end 24, the coolant flows backward to cool the shaft 9 heated by the rotor 10. Furthermore, the lubricant film around the shaft 9 in the gearbox 3 dissipates the heat of the gearbox 3 by carrying heat from inside the gearbox 3 to the shaft 9. Furthermore, the coolant cools the bearings 12, 14, 16 and the radial shaft seal 32 arranged between the first bearing 12 and the rotor 11 to prevent lubricant from entering the air gap of the electromechanical machine 2. In this way, the radial shaft seal 32 forms a system barrier 33 between the wet gearbox 3 and the dry electromechanical machine 2.

[0035] According to another embodiment of Configuration 1, the flowing direction of the coolant is opposite to that of the above embodiment. In this case, the coolant flows into the blind end 24 from the coolant introduction element 21 through the outer region 26 and flows back through the inner region 25.

[0036] According to another embodiment of Configuration 1, the coolant guiding element 22 is configured to rotate with the rotor 10. Thereby, the coolant guiding element 22 is connected to the rotor 10 so as to be torque-resistant, and rotates relative to the coolant introduction element 21.

[0037] FIG. 4 is a block diagram of an embodiment of a vehicle 34 including Configuration 1 according to one of the above embodiments, and Configuration 1 is configured to drive the vehicle 34.

Claims

1. An electromechanical machine (2), a gearbox (3), connecting the electromechanical machine (2) to the gearbox (3), and a shaft (9) extending from a machine-side end (19), which is one side end of the electromechanical machine (2), to the gearbox (3) and having an axially blind hole (18) located at the other side end of the electromechanical machine (2), a coolant introduction element (21) arranged at the machine-side end (19) and configured to supply coolant into the axially blind hole (18), a coolant guiding element (22) extending from the machine-side end (19) into the gearbox (3) inside the axially blind hole (18) and defining a flow path (23) for the introduced coolant, and the shaft (9) is arranged to rotate around the coolant guiding element (22), a first bearing (12) arranged adjacent to a gear (11) connected to a rotor (10) of the electromechanical machine (2) within a drive-end shield (13) of a housing (6) of the electromechanical machine (2), a second bearing (14) arranged within a housing structure (15) of a housing (7) of the gearbox (3), a third bearing (16) arranged within a non-drive-end shield (17) at the machine-side end (19) of the housing (6) of the electromechanical machine (2), a radial shaft seal (32) arranged between the first bearing (12) and the rotor (10) and attached to the shaft (9), and the gear (11) is located between the first bearing (12) and the second bearing (14), the axially blind hole (18) has a through hole axially closed by a closing element (20) in contact with the second bearing (14), the radial shaft seal (32) is cooled by the coolant, characterized by the configuration (1).

2. The configuration according to claim 1, wherein the second bearing (14) supporting the shaft (9) and / or the gear (11) of the gearbox (3) is attached by the closing element (20).

3. The configuration according to claim 1 or 2, wherein a blind end portion (24) of the shaft (9) has a deflecting means (27) configured to swirl the coolant.

4. The configuration according to claim 3, wherein the deflecting means (27) is realized by the closing element (20).

5. The deflecting means (27) has a hole side surface (28) that is non-perpendicular to the axis of rotation (29) of the shaft (9), according to the configuration of claim 3 or 4.

6. The coolant guiding element (22) separates the axial blind hole (18) into an inner region (25) and an outer region (26), and one of the regions (25, 26), in particular the inner region (25), realizes the flow path (23), according to the configuration of any one of claims 1 to 5.

7. The coolant guiding element (22) has an outer shape (30) that extends in the axial direction of the shaft (9) and projects into the outer region (26) and is open in the circumferential direction, in particular a spiral outer shape, according to the configuration of claim 6.

8. The outer shape (30) is realized by an outer shape element (31) arranged around the coolant guiding element (22), according to the configuration of claim 7.

9. The outer shape element (31) is a wire or a ribbon and / or is formed from a polymer, in particular by molding, and / or is formed from a metal, according to the configuration of claim 8.

10. A vehicle (34) comprising the configuration (1) according to any one of claims 1 to 9, which is configured to drive the vehicle (34).

Images