Motor stator

Abstract

An electric machine stator includes a stator core, a stator winding attached to the stator core, a plurality of cooling channels extending through the stator core, and a manifold for delivering fluid into the cooling channels.

Description

Technical Field

[0001] The present application relates to a stator for an electric machine, which includes a stator core, a stator winding attached to the stator core, a plurality of cooling channels extending through the stator core, and a manifold for delivering a fluid into the cooling channels. Background Art

[0002] It is known that in the operation of electric machines such as generators or electric motors for powering motor vehicles, heat losses or copper losses occur. In order to avoid thermal overheating which would lead to a reduction in efficiency or even damage or a reduction in the life, in particular the insulation life, of the corresponding electric machine, cooling devices are provided.

[0003] CN 207475301U discloses an electric motor cooling system, in which a plurality of axial coolant channels are integrated into stator teeth. The axis of each of the axial coolant channels is parallel to the axis of the stator. A coolant manifold assembly integrated into the stator connects the coolant channel fluid in the stator to a coolant source.

[0004] US2021 / 351642A1 discloses an electric motor cooling system that utilizes stator-integrated axial coolant passages and a coolant manifold centrally located within the stator to efficiently remove heat. The coolant manifold includes an intermediate member that allows coolant to enter the axial coolant passages via transition laminations, wherein the transition laminations include coolant distribution passages that direct the coolant flow entering the manifold into the stator-integrated axial coolant passages.

[0005] CN 112886735A discloses a motor stator assembly with a cooling flow channel. The stator includes a stator support and a stator lamination nested in each other, and the stator lamination is provided with a stator winding. The stator winding protrudes outward from the end of the stator lamination in the axial direction, and the stator support is provided with a liquid inlet hole penetrating the peripheral wall of the stator support. A cooling groove is formed between the stator support and the relative peripheral walls of the stator lamination, the cooling groove is connected to the liquid inlet hole, and is open in the axial direction toward the two end portions of the stator lamination to form a liquid outlet. The cooling liquid flows into the cooling groove from the liquid inlet hole, and flows out of the cooling groove from the liquid outlet, so that the stator lamination and the stator winding are cooled. Summary of the invention

[0006] An object may be to provide an electric machine stator with a more efficient and / or more uniform cooling fluid distribution.

[0007] This object is achieved by a stator for an electric machine according to claim 1. Advantageous embodiments are subject to the dependent claims.

[0008] The electric machine stator comprises a stator core, a stator winding attached to the stator core, a plurality of cooling channels extending through the stator core, and two manifolds attached to opposite axial ends of the stator core for conveying fluid into the cooling channels. Each of the two manifolds has a distribution channel hydraulically connected to a portion of the cooling channels, and the flow cross section of the distribution channel decreases along the main circumferential extension direction of the distribution channel.

[0009] By means of two manifolds, the cooling fluid can advantageously be delivered to the cooling channels from both axial ends of the stator rather than from a central inlet as known in the prior art.The reduced flow cross section of the distribution channels provides a more uniform distribution of pressure and flow rate of the cooling fluid.

[0010] The substantially cylindrical stator core may define a longitudinal axis. Unless otherwise specified, references used herein such as axial, radial or circumferential refer to the longitudinal axis of the stator core. The stator winding attached to the stator core may be a hairpin winding. The cooling channel may extend substantially from one axial end of the stator core to the other axial end. The cooling channel may extend straight and parallel to, for example, the longitudinal axis, or extend spirally around the longitudinal axis, or extend at a decreasing or increasing radial distance from the longitudinal axis. The reduced flow cross section of the distribution channel should be understood as a reduction in the cross-sectional area of ​​the distribution channel, which is defined in a plane perpendicular to the flow direction of the cooling fluid. The flow cross section of the cooling channel may have, for example, a circular or quadrilateral form. The manifold may be made of a plastic material and is substantially circular. The distribution channel extends circumferentially along the manifold. The flow cross section of the distribution channel may be, for example, rectangular, and other forms are also feasible. The reduction of the flow cross section of the distribution channel may be continuous or by means of a discrete number of steps. For example, the distribution channel may have a constant height in the radial direction and a decreasing width in the axial direction along the circumferential main extension direction. A person skilled in the art will appreciate that, alternatively or additionally, the height of the distribution channel in the radial direction may decrease along the circumferential main extension direction. The circumferential main extension direction coincides with the flow direction of the cooling fluid.

[0011] The two manifolds may be identical. When a feature of a manifold is indicated in the singular, it is understood that the feature is present in both manifolds. The two manifolds may also be referred to as a first of the two manifolds and a second of the two manifolds, the first manifold having a first distribution channel hydraulically connected to a first portion of the cooling channels, the second manifold having a second distribution channel hydraulically connected to a second portion of the cooling channels, wherein the flow cross section of the first distribution channel decreases along a circumferential main extension of the first distribution channel, and the flow cross section of the second distribution channel decreases along a circumferential main extension of the second distribution channel.

[0012] According to an embodiment, the distribution channel is circular and the flow cross section of the distribution channel decreases from the position of the maximum flow cross section in two circumferential directions. Advantageously, the fluid can be fed to the distribution channel at the position of the maximum flow cross section. The position of the minimum flow cross section of the distribution channel can be at an angular distance of about 180° from the position of the maximum flow cross section on the circumference of the distribution channel. Each manifold may have an inlet located at the position of the maximum flow cross section, but the inlet may be formed by another part other than the manifold. The position of the maximum flow cross section is the position with the highest cross-sectional area along the main extension direction of the distribution channel. The position of the minimum flow cross section is the position with the smallest cross-sectional area along the main extension direction of the distribution channel.

[0013] According to another embodiment, the cooling channels are evenly distributed around the circumference of the stator core and are hydraulically connected to one of the two manifolds in an alternating pattern. If the cooling channels are, for example, alternately connected to one of the two manifolds, the coolant flow in each cooling channel is countercurrent with respect to the corresponding adjacent cooling channel. When heat is transferred to the coolant during its flow through the cooling channels, the coolant temperature is lower at the introduction side and increases along the cooling channels. The staggered first and second portions of cooling channels advantageously balance the cooling effect and provide a more uniform temperature distribution along the stator core. Instead of ABABAB-etc., various alternating patterns of first and second portion of cooling channels can be implemented, such as AABBAABB-etc. or AABABBABAABA-etc., where A represents the first portion and B represents the second portion.

[0014] According to another embodiment, each of the two manifolds has an outlet channel hydraulically connected to the cooling channel of the share, which is hydraulically connected to the distribution channel of the corresponding other of the two manifolds to receive the fluid from the cooling channel of the share. The first manifold has a first outlet channel, which is hydraulically connected to the cooling channel of the second share, and the second manifold has a second outlet channel, which is hydraulically connected to the cooling channel of the first share. The outlet channel may have one or more openings for distributing the fluid. The fluid can be advantageously used to cool the winding heads of the stator winding extending out of the stator core at both axial ends. The openings can be directed toward the winding heads to distribute the fluid onto the winding heads. The manifolds can be arranged axially overlapping and radially outside the winding heads. Each outlet channel can be provided with two or three openings at different axial positions to advantageously cover the winding heads in the axial direction. In addition, at least one of the openings can be directed in a radial direction perpendicular to the axial direction, and at least one other opening can be directed in a radial direction and at an angle to the axial direction.

[0015] According to another embodiment, the distribution channel is formed as a groove in the manifold, which is closed by a housing surrounding the stator core. The housing has at least one inlet hydraulically connected to the distribution channel. The cooling fluid is fed into the cooling channel via the at least one inlet. A single inlet may be hydraulically connected to two distribution channels via two feed channels, which extend axially along the stator core or through the stator core. Alternatively, the housing may have two inlets, each of which is hydraulically connected to one of the distribution channels. Advantageously, the two feed channels or the two inlets may be arranged at the position of the maximum flow cross section of the distribution channel. In addition, the stator may be installed with at least one inlet in the position of maximum potential energy (i.e., on the top of the stator in the installation position of the stator). The cooling circuit may advantageously be passive, without external pressurization, and the cooling fluid is delivered to the distribution channel through the inlet from the reservoir at the position of higher potential energy, enters the cooling channel, and is further delivered to the winding head through the outlet channel and the opening.

[0016] According to another embodiment, the manifold has a positioning device to maintain the relative circumferential position relative to the stator core. The manifolds may each have a gap in the circumferential direction, so that the manifold has a C-shape. The gap may be located at an angular distance of about 180° from the position of the maximum flow cross section. The C-shape facilitates the installation of the manifold inside the housing. The resilient member may be arranged between the two surfaces facing the gap and bias the two surfaces apart. Thus, the radial size of the manifold can be reduced for installation, while the resilient member increases the radial size of the manifold again after installation. The resilient member may be a rubber seal arranged in a groove in the surface facing the gap.

[0017] According to another embodiment, the stator core is composed of a plurality of identical laminations, which is advantageous when manufacturing the stator core, since only one type of sheet metal laminations need to be produced. Alternatively, the stator core can be made in one piece, i.e. as a non-laminated stator core or a solid stator core. A one-piece stator core offers simplicity in manufacturing and assembly, but has disadvantages such as increased eddy current losses leading to reduced efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Exemplary embodiments are illustrated in the context of the accompanying drawings. In the drawings:

[0019] Figure 1 An embodiment of a motor stator is shown in perspective view;

[0020] Figure 2 A cross-sectional perspective view is shown. Figure 1 Embodiments of

[0021] Figure 3 The cross-sectional view shows Figure 2 Magnified details of

[0022] Figure 4 A cross-sectional perspective view is shown through Figure 1 A portion of the oil path of an embodiment;

[0023] Figure 5 Shown in side elevation Figure 1 Two manifolds of an embodiment;

[0024] Figure 6 An enlarged detail of the manifold is shown in perspective view. DETAILED DESCRIPTION

[0025] exist Figure 1 , an embodiment of an electric machine stator 1 according to the invention is depicted in a perspective view. The electric machine stator 1 comprises a stator core 2 and a stator winding attached to the stator core. In the stator winding, only the winding heads 11 extending out of the stator core 2 at the axial end 4 of the stator core are visible. The substantially cylindrical stator core 2 defines a longitudinal axis L which is only axially oriented in the longitudinal direction. Figure 1 Unless otherwise indicated, references to the axial, radial or circumferential directions used to describe any of the drawings refer to Figure 1 The housing 12 according to this embodiment has two inlets 14 for cooling fluid, and surrounds the stator core 2 and the winding heads 11. Two manifolds 3 are attached to the opposite axial ends 4 of the stator core 2, only one of which is in the Figure 1 1. The manifolds 3 are arranged axially overlapping, radially outside the winding heads 11 and radially inside the housing 12. The manifolds 3 each have a gap 16 in the circumferential direction, and the resilient member 17 is arranged between the two surfaces facing the gap 16 and biases the two surfaces apart. The manifolds 3 can be installed by reducing their radial dimensions during insertion into the housing 12. The biasing force of the resilient member 17 contributes to the tight fit of the manifold 3 in the housing 12.

[0026] exist Figure 2 , a longitudinal section along the longitudinal axis L is shown in perspective view. Figure 1 Embodiment. A plurality of cooling channels 6 extend through the stator core 2, and two manifolds 3 are attached to opposite axial ends 4 of the stator core 2 for conveying a cooling fluid into the cooling channels 6. A gasket 18 seals the manifold against the housing 12. Each of the two manifolds 3 (which may also be referred to as a first manifold 3' and a second manifold 3") has a distribution channel 5 hydraulically connected to a portion of the cooling channels 6. The flow cross section of the distribution channel 5 decreases along the circumferential main extension direction of the distribution channel 5. The cooling fluid is fed to the distribution channel 5 at the position of the maximum flow cross section 7. The position of the minimum flow cross section 8 of the distribution channel 5 is at an angular distance of about 180° from the position of the maximum flow cross section 7 on the circumference of the distribution channel 5.

[0027] The cooling channels 6 are evenly distributed around the circumference of the stator core 2 and are hydraulically connected to one of the two manifolds 3 in an alternating pattern, such as, for example, ABABAB-etc. or AABBAABB-etc. or AABABBABAABA-etc., where A represents a first portion of the cooling channels 6 and B represents a second portion of the cooling channels 6. In the depicted embodiment, the distribution channels 5 of the first manifold 3' are connected to one of the cooling channels 6 at the location of the minimum flow cross section 8. The distribution channels 5 of the second manifold 3" are connected to one of the cooling channels 6 at the location of the maximum flow cross section 7 where the inlet 14 is located. The inlet 14 is circumferentially offset relative to each other by the distance between two adjacent cooling channels 6, which also applies to the corresponding positions of the maximum flow cross section 7 and the minimum flow cross section 8. The stator core 2 can be equipped with the inlet 14 approximately in the position of maximum potential energy to allow passive conveying of the cooling fluid by gravity. The stator core 2 can be composed of a plurality of sheet metal laminations, which are advantageously identical.

[0028] Each of the two manifolds 3 has an outlet channel 9. The outlet channel 9 of the first manifold 3' is hydraulically connected to the portion of the cooling channel 6, which is hydraulically connected to the distribution channel 5 of the second manifold 3", and vice versa. The outlet channel 9 receives the cooling fluid from the corresponding cooling channel 6, which is distributed from the outlet channel 9 through at least one opening 10, which will be combined with Figure 3 Give a description.

[0029] exist Figure 3 In the figure, a cross-sectional view without the housing 12 is shown. Figure 2 . The openings 10 of the outlet channel 9 are directed towards the winding heads 11 extending out of the stator core 2 to distribute the cooling fluid onto the winding heads 11. The openings 10 of each outlet channel 9 have different axial positions to advantageously cover the winding heads 11. In the depicted embodiment, each outlet channel 9 is provided with two openings 10 in different axial positions, one of the openings 10 being directed in a radial direction perpendicular to the axial direction, and the other of the openings 10 being directed in the radial direction and at an angle to the axial direction. However, the two openings 10 may also be directed in a radial direction perpendicular to the axial direction. The distribution channel 5 is formed as a groove in the manifold 3, which is closed by a housing 12 surrounding the stator core 2. A gasket 18 is also located in a groove axially outside the distribution channel 5.

[0030] exist Figure 4 , partially shown in a cross-sectional perspective view through Figure 1. Depicted are walls or surfaces delimiting the oil path from a first manifold 3 ′, which feeds the fluid via an inlet 14 and distributes it to one of the cooling channels 6 comprising said share of half of the cooling channels 6 . The downstream end is formed by an outlet channel with an opening 10 , which is formed by a second manifold 3 ″. The distribution channel 5 is substantially circular, interrupted by a gap 16. The flow cross section of the distribution channel 5 decreases in both circumferential directions from the inlet 14 or the location of the maximum flow cross section 7 .

[0031] exist Figure 5 In the side elevation view, Figure 1 Two manifolds 3 of the embodiment. The flow cross section of the distribution channel 5 decreases in both circumferential directions from the position of the maximum flow cross section 7 to the position of the minimum flow cross section 8, which distribution channel 5 can be called a first distribution channel 5' in the first manifold 3' and a second distribution channel 5" in the second manifold 3". The distribution channel 5 can have a constant height in the radial direction and a decreasing width in the axial direction along the circumferential main extension direction. The manifold 3 has a positioning device 15 to maintain the relative circumferential position with respect to the stator core 2.

[0032] exist Figure 6 , an enlarged detail of the manifold 3 is shown in perspective. In the gap 16, a resilient member 17, for example in the form of a rubber seal, is arranged between two surfaces facing the gap 16, the resilient member 17 resting in corresponding grooves 19 in the surfaces. On the inner surface of the manifold, the openings 10 from the outlet channels are visible.

[0033] Reference numerals

[0034] 1 Motor stator

[0035] 2 Stator core

[0036] 3 Manifold

[0037] 3' first manifold

[0038] 3” Second Manifold

[0039] 4 Axial end

[0040] 5 Assign channels

[0041] 5'First distribution channel

[0042] 5” second distribution channel

[0043] 6 Cooling channels

[0044] 7 Location of maximum flow cross section

[0045] 8 Location of minimum flow cross section

[0046] 9 Exit Channel

[0047] 10 Opening

[0048] 11 Winding head

[0049] 12 Housing

[0050] 14 Entrance

[0051] 15 Positioning device

[0052] 16 Gap

[0053] 17 Resilient member

[0054] 18 Washer

[0055] 19 Grooves

[0056] L Longitudinal axis

Claims

1. A motor stator (1), comprising: a stator core (2), a stator winding attached to the stator core, a plurality of cooling channels (6) extending through the stator core (2), and two manifolds (3) attached to opposite axial ends (4) of the stator core (2) for conveying a fluid into the cooling channels (6), Each of the two manifolds (3) has a distribution channel (5) which is hydraulically connected to a portion of the cooling channel (6), Therein, the flow cross section of the distribution channel decreases along the circumferential main extension direction of the distribution channel (5).

2. The motor stator according to claim 1, characterized in that: The distribution channel (5) is circular and its flow cross section decreases in both circumferential directions from the location of the maximum flow cross section (7), wherein the fluid is fed to the distribution channel (5) at the location of the maximum flow cross section (7).

3. The motor stator according to claim 2, characterized in that: The position of the minimum flow cross section (8) of the distribution channel (5) is at an angular distance of approximately 180° from the position of the maximum flow cross section (7) on the circumference of the distribution channel.

4. The stator of an electric machine according to any one of the preceding claims, characterized in that The cooling channels (6) are evenly distributed around the circumference of the stator core (2) and are hydraulically connected to one of the two manifolds (3) in an alternating pattern.

5. The stator of an electric machine according to any one of the preceding claims, characterized in that Each of the two manifolds (3) has an outlet channel (9) hydraulically connected to the portion of the cooling channel (6), the portion of the cooling channel being hydraulically connected to the distribution channel (5) of the respective other of the two manifolds to receive fluid from the portion of the cooling channel, wherein the outlet channel (9) has at least one opening (10) for distributing the fluid.

6. A stator for an electric machine according to any one of the preceding claims, characterised in that The distribution channels (5) are formed as grooves in the manifold (3), which grooves are closed by a housing (12) surrounding the stator core (2), wherein the housing (12) has at least one inlet (14) hydraulically connected to at least one of the distribution channels (5).

7. The motor stator according to claim 6, characterized in that: In the installed position, the at least one inlet (14) is arranged in a position of maximum potential energy.

8. A stator for an electric machine according to any one of the preceding claims, characterised in that The manifold (3) has a positioning device (15) to maintain a relative circumferential position relative to the stator core (2).

9. A stator for an electric machine according to any one of the preceding claims, characterised in that The manifolds (3) each have a gap (16) in the circumferential direction, and a resilient member (17) is arranged between two surfaces facing the gap and biases the two surfaces apart.

10. A stator for an electric machine according to any one of the preceding claims, characterised in that The stator core (2) is composed of a plurality of identical laminations.

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