CN220711253U - Shaft assembly for motor, motor and electric drive axle - Google Patents

Abstract

The present application proposes a shaft assembly for an electric machine, the shaft assembly comprising: a rotor shaft having a through-hole with an inlet for inflow of lubrication and/or cooling liquid; an inner shaft adapted to be coaxially and interstitially received within the through-hole; wherein a gap formed in a radial direction between the rotor shaft and the inner shaft has a gap first axial section adjoining an inlet of the through-hole, the gap has a gap second axial section adjacent to the gap first axial section, and a through-flow cross-sectional area of the gap gradually decreases in the gap first axial section and gradually increases in the gap second axial section in a first axial direction directed from the inlet toward an inside of the through-hole. The application has the advantages that: oil can be caused to flow into and fill the gap between the rotor shaft and the inner shaft, thereby establishing pressure such that sufficient lubrication and/or cooling fluid can be thrown out through the radial holes of the rotor shaft.

Description

Shaft assembly for motor, motor and electric drive axle

Technical Field

The present application relates to a shaft assembly for an electric motor, an electric motor and an electrically driven bridge.

Background

In the prior art, some electrically driven bridges have coaxial motors. The coaxial motor has a rotor shaft and an inner shaft received in a through hole of the rotor shaft. The through bore of the rotor shaft is cylindrical, while the inner shaft is correspondingly cylindrical. A gap is provided between the rotor shaft and the inner shaft to allow oil to flow in. The rotor shaft is also provided with radial holes, so that oil in the gap can be thrown out through the radial holes, and lubrication and cooling are carried out on the stator of the motor and the bearing of the rotor shaft. The clearance between the rotor shaft and the inner shaft is typically small. The reason for this is that: on the one hand, the inner axle forming the axle needs to be made as large as possible to increase strength; on the other hand, the inner diameter of the rotor shaft is made as small as possible to make the motor compact. Because the gap is small, it is often difficult for oil to enter the gap, and thus the gap is difficult to fill with oil. If the gap is not filled with oil, it is also difficult for the oil to be thrown out of the radial holes of the rotor shaft, so that the components are not cooled and lubricated as desired.

Disclosure of Invention

It is an object of the present application to provide a shaft assembly for an electric machine such that lubrication and/or cooling fluid can be induced into a gap between a rotor shaft and an inner shaft of the shaft assembly.

According to a first aspect of the present application, there is provided a shaft assembly for an electric machine, the shaft assembly comprising:

a rotor shaft having a through-hole with an inlet for inflow of lubrication and/or cooling liquid;

an inner shaft adapted to be coaxially and interstitially received within the through-hole;

wherein a gap formed in a radial direction between the rotor shaft and the inner shaft has a gap first axial section adjoining an inlet of the through-hole, the gap has a gap second axial section adjacent to the gap first axial section, and a through-flow cross-sectional area of the gap gradually decreases in the gap first axial section and gradually increases in the gap second axial section in a first axial direction directed from the inlet toward an inside of the through-hole.

According to an alternative embodiment of the present application, the through hole has:

a through-hole first axial section forming the gap first axial section;

a through hole second axial section forming the gap second axial section;

wherein the through-hole first axial section is configured in a ramp shape and is adapted to reduce the through-flow cross-sectional area of the through-hole in the first axial direction, and/or the through-hole second axial section is configured in a ramp shape and is adapted to increase the through-flow cross-sectional area of the through-hole in the first axial direction.

According to an alternative embodiment of the present application, the through-hole first axial section and/or the through-hole second axial section are configured in a straight ramp shape or an arcuate ramp shape.

According to an alternative embodiment of the present application, the inner shaft has:

an inner shaft first axial section forming the gap first axial section;

an inner axial second axial section forming the gap second axial section;

wherein the inner shaft first axial section is configured in a ramp shape and is adapted to increase the cross-sectional area of the inner shaft in the first axial direction, or the inner shaft second axial section is configured in a ramp shape and is adapted to decrease the cross-sectional area of the inner shaft in the first axial direction.

According to an alternative embodiment of the present application, the inner shaft first axial section or the inner shaft second axial section is configured in a straight ramp shape or an arcuate ramp shape.

According to an alternative embodiment of the present application, the motor is configured as a coaxial motor for an electrically driven bridge, the inner shaft being configured to be driven by the rotor shaft via a decelerator of the electrically driven bridge.

According to an alternative embodiment of the present application, the gap first axial section and the gap second axial section are directly inter-engaged.

According to an alternative embodiment of the present application, the gap first axial section is spaced from the gap second axial section via a spacing axial section of the gap, and the axial length of the spacing axial section is not more than one fifth of the axial length of the gap first axial section.

According to an alternative embodiment of the present application, the rotor shaft has a radial bore in communication with the through bore, the radial bore being configured to allow lubrication and/or cooling fluid within the through bore to flow out of the radial bore.

According to an alternative embodiment of the present application, the radial bore is downstream of the gap second axial section in the first axial direction.

According to an alternative embodiment of the present application, the radial holes comprise a first radial hole for lubrication cooling of the bearing of the rotor shaft and/or a second radial hole for lubrication cooling of the wire package of the stator of the electric machine.

According to an alternative embodiment of the present application, the through hole has an outlet for the outflow of the lubricating and/or cooling liquid, the gap has a gap outlet axial section adjoining the outlet, the gap outlet axial section being hollow cylindrical.

According to an alternative embodiment of the present application, the gap has a gap intermediate axial section following the gap second axial section in the first axial direction, the gap intermediate axial section having a constant through-flow cross-sectional area.

According to an alternative embodiment of the present application, the through-flow cross-sectional area of the gap outlet axial section is smaller than the through-flow cross-sectional area of the gap intermediate axial section.

According to a second aspect of the present application, there is provided an electric machine comprising the aforementioned shaft assembly for an electric machine.

According to a third aspect of the present application, there is provided an electrically driven bridge comprising the aforementioned electric motor.

In at least some embodiments, the positive effects of the present application are: can promote lubrication and/or cooling liquid to flow into the gap between the rotor shaft and the inner shaft; the gap can be filled with lubrication and/or cooling fluid and pressure can be built up so that sufficient lubrication and/or cooling fluid can be thrown out through the radial holes of the rotor shaft to achieve sufficient lubrication and/or cooling.

Drawings

The principles, features and advantages of the present application may be better understood by describing the present application in more detail with reference to the drawings. The drawings include:

fig. 1 schematically shows an example of a part of a cross section of an electrically driven bridge of the present application.

Fig. 2 schematically illustrates an example of a portion of a cross section of a shaft assembly.

Fig. 3 shows the region marked with a dashed circle in fig. 2 in an enlarged schematic view.

Fig. 4 schematically illustrates a second example of a shaft assembly of the present application in a partial cross-sectional view.

Fig. 5 schematically illustrates a third example of a shaft assembly of the present application in a partial cross-sectional view.

Fig. 6 schematically illustrates a fourth example of a shaft assembly of the present application in a partial cross-sectional view.

Fig. 7 schematically illustrates a fifth example of a shaft assembly of the present application in a partial cross-sectional view.

Detailed Description

In order to make the technical problems, technical solutions and advantageous technical effects to be solved by the present application more apparent, the present application will be further described in detail with reference to the accompanying drawings and a plurality of exemplary embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the present application.

Fig. 1 schematically shows an example of a part of a cross section of an electrically driven bridge of the present application. The electric drive axle is used to drive the wheels of a vehicle. The electrically driven bridge comprises an electric motor 1. The motor 1 is here a coaxial motor and has a shaft assembly 2. The shaft assembly 2 includes a rotor shaft 3 and an inner shaft 5 accommodated within the rotor shaft 3.

Fig. 2 schematically shows an example of a part of a cross section of the shaft assembly 2. For clarity, the gap 6 formed between the rotor shaft 3 and the inner shaft 5 in the radial direction 7 (see fig. 3) is shown exaggerated here.

As shown in fig. 2, the rotor shaft 3 has a through-hole 4, the through-hole 4 having an inlet 43 for the inflow of lubricating and/or cooling fluid, in particular oil. Opposite the inlet 43, the through-hole 4 has an outlet 45 at the other end for the outflow of lubrication and/or cooling fluid. The inner shaft 5 is accommodated in the through hole 4 of the rotor shaft 3 coaxially with the rotor shaft 3 with a clearance. In the installed state, the inner shaft 5 protrudes from the rotor shaft 3, in particular in the axial direction, at both ends. The remainder of the electric drive bridge, the motor 1 and the inner shaft 5 are not relevant to the present application and are well known to the person skilled in the art and are not shown in the figures here.

The lubricating and/or cooling fluid flows from the gravity tank via the oil channel to the inlet 43 of the through-hole 4 or the gap 6 and via the inlet 43 into the gap 6 and finally out via the outlet 45 of the through-hole 4 or the gap 6. Radial holes 44 (see fig. 1) are also provided in the rotor shaft 3 in communication with the through holes 4, so that lubrication and/or cooling liquid in the gap 6 is thrown out via the radial holes 44, thereby cooling and/or lubricating the components of the electric machine 1, such as the stator and bearings.

In the case of the existing electric drive bridge or motor 1, the through-opening 4 of the rotor shaft 3 is cylindrical, while the inner shaft 5 is correspondingly cylindrical. The gap 6 between the rotor shaft 3 and the inner shaft 5 is typically small. The reason for this is that: on the one hand, the inner shaft 5 forming the axle needs to be made as large as possible to improve strength; on the other hand, the inner diameter of the rotor shaft 3 is made as small as possible to make the motor 1 compact. Since the gap 6 is small, it is often difficult for lubrication and/or cooling fluid to enter the gap 6, so that the gap 6 is difficult to fill with lubrication and/or cooling fluid. If the gap 6 is not filled with lubrication and/or cooling liquid, it is also difficult for the lubrication and/or cooling liquid to be thrown out of the radial holes 44 of the rotor shaft 3, so that the stator and bearings of the electric machine 1 are not properly cooled and lubricated.

In this regard, the present application proposes an improved shaft assembly 2.

Fig. 3 shows the region marked with a dashed circle in fig. 2 in an enlarged schematic view.

As shown in fig. 2 and 3, the gap 6 between the rotor shaft 3 and the inner shaft 5 has a gap first axial section 61 adjoining the inlet 43 of the through-hole 4, the gap 6 has a gap second axial section 62 adjacent to the gap first axial section 61, and the through-flow cross-sectional area of the gap 6 gradually decreases in the gap first axial section 61 and gradually increases in the gap second axial section 62 in a first axial direction 8 directed from the inlet 43 toward the inside of the through-hole 4.

The gap second axial section 62 is understood to be inward in the first axial direction 8 relative to the gap first axial section 61. The gap second axial section 62 is adjacent to the gap first axial section 61, in particular it is understood that the throttling effect formed by the gap first axial section 61 and the gap second axial section 62 near their junction is negligible.

Since the through-flow cross-sectional area of the gap 6 gradually decreases in the gap first axial section 61, i.e. at the inlet 43 in the first axial direction 8, the flow velocity of the lubrication and/or cooling fluid gradually increases, which increases the flow velocity brings about a reduced pressure, thereby creating a suction force for sucking the lubrication and/or cooling fluid into the gap 6. Furthermore, if the gap second axial section 62 is straight, a throttle may be formed in the gap second axial section 62, whereas if the gap second axial section 62 increases stepwise from the end point of the gap first section 61, turbulence may be formed to the detriment of lubrication and/or coolant passage. The through-flow cross-sectional area of the gap 6 is thus designed to increase gradually in the gap second axial section 62. As a result, the lubrication and/or coolant can flow into the interior of the gap 6 and fill the gap 6, as a whole, thereby establishing pressure. By means of this pressure it is ensured that sufficient lubrication and/or cooling liquid is thrown out via the radial holes 44 of the rotor shaft 3 for lubricating and/or cooling the components of the electric machine 1.

Gradual decrease is understood to mean, in particular, monotonic decrease, in particular strictly monotonic decrease. A gradual increase is understood to mean in particular a monotonic increase, in particular a strictly monotonic increase.

According to an exemplary embodiment, as shown in fig. 1 and 2, the radial bore 44 is downstream of the gap second axial section 62 in the first axial direction 8. It is also conceivable, however, to provide radial bores 44 in the gap second axial section 62.

According to an exemplary embodiment, as shown in fig. 3, the through hole 4 has:

a through-hole first axial section 41 forming a gap first axial section 61;

a through-hole second axial section 42 forming a gap second axial section 62;

wherein the through-hole first axial section 41 is configured in a ramp shape and is adapted to reduce the through-flow cross-sectional area of the through-hole 4 in the first axial direction 8, and the through-hole second axial section 42 is configured in a ramp shape and is adapted to increase the through-flow cross-sectional area of the through-hole 4 in the first axial direction 8. The corresponding region of the inner shaft 5 is here exemplarily straight.

In fig. 3, the through-hole first axial section 41 and the through-hole second axial section 42 are exemplarily configured in a straight slope shape. It is also conceivable, however, for the through-hole first axial section 41 and/or the through-hole second axial section 42 to be configured in the shape of an arcuate ramp. The arcs may include convex arcs, concave arcs, and any combination of the two.

Fig. 4 schematically shows a second example of the shaft assembly 2 of the present application in a partial cross-sectional view.

According to an exemplary embodiment, as shown in fig. 4, the inner shaft 5 has:

an inner shaft first axial section 51 forming a gap first axial section 61;

an inner axial section 52 forming a gap second axial section 62;

wherein the inner shaft first axial section 51 is configured in a ramp shape and adapted to increase the cross-sectional area of the inner shaft 5 in the first axial direction 8, and the inner shaft second axial section 52 is configured in a ramp shape and adapted to decrease the cross-sectional area of the inner shaft 5 in the first axial direction 8. The corresponding regions of the through-hole 4, namely the through-hole first axial section 41 and the through-hole second axial section 42, are here by way of example straight. The solution of fig. 4 is at least theoretically possible.

Similar to the through-hole 4, the inner shaft first axial section 51 and/or the inner shaft second axial section 52 may be configured in a straight ramp shape or an arcuate ramp shape.

Fig. 5 schematically shows a third example of the shaft assembly 2 of the present application in a partial cross-sectional view.

According to an exemplary embodiment, as shown in fig. 5, the through-hole first axial section 41 is configured in a ramp shape and is adapted to reduce the through-flow cross-sectional area of the through-hole 4 in the first axial direction 8, while the through-hole second axial section 42 is straight; the inner shaft first axial section 51 is straight, while the inner shaft second axial section 52 is configured in a ramp shape and is adapted to reduce the cross-sectional area of the inner shaft 5 in the first axial direction 8. The technical idea of the present application can also be realized in this way.

Fig. 6 schematically shows a fourth example of the shaft assembly 2 of the present application in a partial cross-sectional view.

According to an exemplary embodiment, as shown in fig. 6, the through-hole first axial section 41 is straight, while the through-hole second axial section 42 is configured in a ramp shape and is adapted to increase the through-flow cross-sectional area of the through-hole 4 in the first axial direction 8; the inner shaft first axial section 51 is configured in a ramp shape and is adapted to increase the cross-sectional area of the inner shaft 5 in the first axial direction 8, while the inner shaft second axial section 52 is straight. The technical idea of the present application can also be realized in this way.

According to an exemplary embodiment, as shown in fig. 3 to 6, the gap first axial section 61 and the gap second axial section 62 are directly in engagement with each other.

Fig. 7 schematically illustrates a fifth example of the shaft assembly 2 of the present application in a partial cross-sectional view.

According to an exemplary embodiment, as shown in fig. 7, the gap first axial section 61 is spaced apart from the gap second axial section 62 via a spacing axial section 64 of the gap 6, and the axial length of the spacing axial section 64 does not exceed one fifth, in particular one tenth, of the axial length of the gap first axial section 61. The distance axial section 64 of the gap 6 is, for example, hollow-cylindrical. The spacing axial section 64 should in particular satisfy the following conditions: the throttling effect created by the spaced axial segments 64 is negligible.

It is clear that the solution of the present application is not limited to the exemplary embodiments described above, but that various combinations are also possible, which are not further listed here.

In the above example, the motor 1 is a coaxial motor for an electrically driven bridge, while the inner shaft 5 is driven by the rotor shaft 3 via a reducer of the electrically driven bridge. But this is only one exemplary application. The motor 1 may also be a motor 1 for other devices, and the inner shaft 5 is not necessarily required to be in driving connection with the rotor shaft 3 of the motor 1.

According to an exemplary embodiment, as shown in fig. 1 and 2, the radial holes 44 comprise a first radial hole 441 for lubrication cooling of the bearings of the rotor shaft 3 and/or a second radial hole 442 for lubrication cooling of the coils of the stator of the electric machine 1. It is also conceivable that the rotor shaft 3 is also provided with radial holes 44 for cooling other components of the electric machine 1. The number and distribution of radial holes 44 in fig. 1 and 2 is only an example, and various possibilities are also envisaged by the person skilled in the art.

According to an exemplary embodiment, as shown in fig. 1 and 2, the through-hole 4 has an outlet 45 for the outflow of lubrication and/or cooling liquid, the gap 6 has a gap outlet axial section 63 adjoining the outlet 45, the gap outlet axial section 63 being hollow-cylindrical (in particular if a process chamfer at the outlet 45 is omitted). There is no need to provide a complex structure at the outlet 45 to save costs.

According to an exemplary embodiment, as shown in fig. 2, the gap 6 has a gap intermediate axial section 65 which follows the gap second axial section 62 in the first axial direction 8, the gap intermediate axial section 65 having a constant through-flow cross-sectional area. The gap intermediate axial section 65 may form a large space for containing lubrication and/or cooling fluid.

According to an exemplary embodiment, as shown in fig. 2, the through-flow cross-sectional area of the gap outlet axial section 63 is smaller than the through-flow cross-sectional area of the gap intermediate axial section 65. Thereby making it less easy for lubrication and/or cooling fluid to flow out of the outlet 45, thereby helping to fill the gap 6 with lubrication and/or cooling fluid and build up pressure.

It is noted that the dimensions and mutual proportions of the elements in the figures are to be understood by way of example only and do not necessarily require the elements to have the dimensions and mutual proportions in the figures.

Although specific embodiments of the present application have been described in detail herein, they are presented for purposes of illustration only and are not to be construed as limiting the scope of the present application. Various substitutions, alterations, and modifications can be made without departing from the spirit and scope of the application.

List of reference numerals

1. Motor with a motor housing

2. Shaft assembly

3. Rotor shaft

4. Through hole

41. A first axial section of the through hole

42. Through-hole second axial section

43. An inlet

44. Radial hole

441. First radial hole

442. Second radial hole

45. An outlet

5. Inner shaft

51. First axial section of inner shaft

52. Inner shaft second axial section

6. Gap of

61. A gap first axial section

62. Gap second axial section

63. Gap outlet axial section

64. Spaced axial sections

65. Gap intermediate axial section

7. Radial direction

8. First axial direction

Claims (10)

1. A shaft assembly for an electric machine, characterized in that the shaft assembly (2) comprises:

-a rotor shaft (3), the rotor shaft (3) having a through-hole (4), the through-hole (4) having an inlet (43) for inflow of lubrication and/or cooling liquid;

an inner shaft (5) adapted to be coaxially and with a gap accommodated within the through hole (4);

wherein a gap (6) formed between the rotor shaft (3) and the inner shaft (5) in a radial direction (7) has a gap first axial section (61) adjoining an inlet (43) of the through-hole (4), the gap (6) having a gap second axial section (62) adjacent to the gap first axial section (61), a through-flow cross-sectional area of the gap (6) gradually decreasing in the gap first axial section (61) and gradually increasing in the gap second axial section (62) in a first axial direction (8) directed from the inlet (43) into the through-hole (4).

2. Shaft assembly for an electric machine according to claim 1, characterized in that the through hole (4) has:

a through-hole first axial section (41) forming the gap first axial section (61);

-a through hole second axial section (42) forming said gap second axial section (62);

wherein the through-hole first axial section (41) is configured in a ramp shape and is adapted to reduce the through-flow cross-sectional area of the through-hole (4) along the first axial direction (8), and/or the through-hole second axial section (42) is configured in a ramp shape and is adapted to increase the through-flow cross-sectional area of the through-hole (4) along the first axial direction (8);

wherein the through-hole first axial section (41) and/or the through-hole second axial section (42) are configured as straight ramp shapes or curved ramp shapes.

3. Shaft assembly for an electric machine according to claim 1 or 2, characterized in that the inner shaft (5) has:

an inner shaft first axial section (51) forming the gap first axial section (61);

an inner axial second axial section (52) forming the gap second axial section (62);

wherein the inner shaft first axial section (51) is configured in a ramp shape and is adapted to increase the cross-sectional area of the inner shaft (5) in the first axial direction (8), or the inner shaft second axial section (52) is configured in a ramp shape and is adapted to decrease the cross-sectional area of the inner shaft (5) in the first axial direction (8);

wherein the inner shaft first axial section (51) or the inner shaft second axial section (52) is configured in a straight ramp shape or an arcuate ramp shape.

4. Shaft assembly for an electric motor according to claim 1 or 2, characterized in that the electric motor (1) is configured as a coaxial motor for an electrically driven bridge, the inner shaft (5) being configured to be driven by the rotor shaft (3) via a reducer of the electrically driven bridge.

5. A shaft assembly for an electric machine according to claim 1 or 2, characterized in that,

-said gap first axial section (61) and said gap second axial section (62) are directly inter-engaged; or (b)

The gap first axial section (61) is spaced from the gap second axial section (62) via a spacing axial section (64) of the gap (6), and the axial length of the spacing axial section (64) is no more than one fifth of the axial length of the gap first axial section (61).

6. A shaft assembly for an electric machine according to claim 1 or 2, characterized in that,

-the rotor shaft (3) has a radial hole (44) communicating with the through hole (4), the radial hole (44) being configured to allow lubrication and/or cooling liquid inside the through hole (4) to flow out of the radial hole (44);

-along the first axial direction (8), the radial hole (44) being downstream of the gap second axial section (62);

the radial bores (44) comprise a first radial bore (441) for lubrication cooling of the bearings of the rotor shaft (3) and/or a second radial bore (442) for lubrication cooling of the coils of the stator of the electric machine (1).

7. Shaft assembly for an electric machine according to claim 1 or 2, characterized in that the shaft assembly (2) comprises at least one of the following features:

the through-hole (4) has an outlet (45) for the outflow of the lubricating and/or cooling liquid, the gap (6) having a gap outlet axial section (63) adjoining the outlet (45), the gap outlet axial section (63) being hollow cylindrical;

the gap (6) has a gap intermediate axial section (65) following the gap second axial section (62) in the first axial direction (8), the gap intermediate axial section (65) having a constant through-flow cross-sectional area.

8. The shaft assembly for an electric machine according to claim 7, characterized in that the through-flow cross-sectional area of the gap outlet axial section (63) is smaller than the through-flow cross-sectional area of the gap intermediate axial section (65).

9. An electric machine, characterized in that the electric machine (1) comprises a shaft assembly for an electric machine according to any one of claims 1 to 8.

10. An electrically driven bridge, characterized in that it comprises an electric machine according to claim 9.