Stator assembly

Abstract

A stator assembly for a brushless permanent magnet motor includes first, second, and third stator core assemblies, each of the first, second, and third stator core assemblies including a stator core segment and a coil wound around the stator core segment. Each stator core segment spans an arc length of approximately 120 degrees. Each coil is wound around a respective stator core segment such that the coil covers a radially inner surface and a radially outer surface of the stator core segment. The coils are connected such that the stator assembly includes a three-phase stator assembly.

Description

Technical Field

[0001] The present invention relates to a stator assembly for a brushless permanent magnet motor and to a brushless permanent magnet motor comprising the stator assembly. Background Art

[0002] It is often desirable to improve electric motors, such as brushless motors, in a variety of ways. For example, improvements may be desired in size, weight, power density, manufacturing cost, efficiency, reliability, and noise. Summary of the Invention

[0003] According to a first aspect of the present invention, a stator assembly for a brushless permanent magnet motor is provided, the stator assembly comprising: first, second and third stator core assemblies, each of the first, second and third stator core assemblies comprising a stator core segment and a coil wound around the stator core segment; wherein each stator core segment spans an arc length of approximately 120 degrees, each coil is wound around the corresponding stator core segment so that the coil covers the radial inner surface and the radial outer surface of the stator core segment, and the coils are connected so that the stator assembly comprises a three-phase stator assembly.

[0004] For the stator assembly of a brushless permanent magnet motor, dividing the stator core into segments can increase the reluctance of the stator assembly, thereby providing resistance to magnetic flux attempting to pass between the stator core segments, given the air gaps between the stator core segments. Furthermore, with each incremental integer increase in the number of stator core segments, reliably and securely connecting the stator core segments together can become more challenging, which can result in a change in the global form of the stator assembly. This change in form can introduce saliency, which can inhibit the generation of the desired magnetic torque in the brushless permanent magnet motor.

[0005] However, it may be desirable to increase the number of segments to facilitate the manufacture of the stator assembly. For example, increasing the number of segments forming the annular stator core may enable the stator core segments to be more linear than would be the case if the annular stator core were formed using a smaller number of segments. This may facilitate the formation of the laminations forming the stator core segments, for example by enabling an increased number of laminations to be formed from a single piece of material, thereby reducing material waste and cost.

[0006] Furthermore, a toroidal core or a two-part core in which each segment spans a 180-degree arc length may provide a winding machine with reduced access to the interior of the bend defined by the stator core segments compared to, for example, a bend of shorter arc length. Shorter arc length stator core segments may enable utilization of an easier and / or less expensive winding process.

[0007] It has been found that the stator assembly according to the first aspect of the invention provides a good compromise between the competing factors mentioned above.

[0008] The stator assembly may include a slotless stator assembly.

[0009] Each of the first stator core assembly, the second stator core assembly, and the third stator core assembly can include a first coil and a second coil, such that the stator assembly includes a total of six coils. The use of six coils can provide a relatively small radial load on a rotor assembly associated with the stator assembly in use, compared to, for example, an arrangement using three coils. The first coil and the second coil can be substantially evenly spaced around the circumference of the stator assembly.

[0010] The first coil and the second coil of each respective stator assembly can be wound in opposite directions. Because each stator core assembly includes the same number of coils, with one coil wound in each direction, e.g., left-handed or right-handed, the stator core assemblies can be substantially similar in form, which can reduce the cost and / or complexity of the manufacturing process of the stator assemblies compared to, for example, stator assemblies using stator core assemblies of different forms.

[0011] The first and second coils of each respective stator assembly can be wound using a single wire, for example using a continuous winding process, which can reduce the manufacturing cost and complexity of the stator assembly compared to, for example, a stator assembly that uses a separate wire to wind each coil.

[0012] Each of the first, second, and third stator core assemblies may include a respective bobbin, each bobbin including a first connection formation and a second connection formation that connect to the respective second connection formation and first connection formation of an adjacent stator core assembly of the first, second, and third stator core assemblies. Providing the connection formations on the bobbins rather than on the stator core segments may reduce magnetic resistance and / or saliency that may otherwise arise due to, for example, shape variations of the stator core segments due to manufacturing tolerances.

[0013] Each of the stator core segments may include a generally planar first end surface and a second end surface that contact corresponding generally planar second end surfaces and first end surfaces of adjacent stator core assemblies of the first, second, and third stator core assemblies in the stator assembly. This may reduce magnetic resistance compared to, for example, an arrangement in which the stator core segments have interfaces with more complex geometries, where the shapes of the stator core segments may vary due to manufacturing tolerances.

[0014] The stator assembly may have an outer diameter of no greater than 40 mm, e.g., no greater than 35 mm, no greater than 30 mm, no greater than 25 mm, or no greater than 20 mm. Providing three stator core segments, each spanning an arc length of approximately 120 degrees, in a stator assembly of this size may facilitate winding of the coils, compared to, for example, an arrangement in which a single annular stator core is provided in a stator assembly of a similar outer diameter.

[0015] Each stator core segment may comprise a height greater than its thickness, for example a height greater than its radial extent.Each stator core segment may comprise a stack of laminations.

[0016] Each stator core assembly may include the same number of terminal connections to which the corresponding coils are connected. This may ensure an even distribution of the terminal connections between the stator core assemblies.

[0017] Each of the first stator core assembly, the second stator core assembly, and the third stator core assembly may comprise substantially the same form. This may reduce the manufacturing cost and complexity of the stator assembly compared to, for example, stator assemblies using stator core assemblies of different forms.

[0018] According to a second aspect of the present invention, there is provided a brushless permanent magnet motor comprising a stator assembly according to the first aspect of the present invention.

[0019] The coils, when energized, can generate a magnetic field that interacts with the permanent magnets of the rotor assembly of the brushless permanent magnet motor to rotate the rotor assembly relative to the stator assembly.

[0020] The brushless permanent magnet motor may be configured to operate at approximately 400 V, for example where the coils are configured to receive a DC link voltage of approximately 400 V.

[0021] According to a third aspect of the present invention, there is provided a hair care appliance comprising a brushless permanent magnet motor according to the second aspect of the present invention.

[0022] According to a fourth aspect of the present invention, there is provided a vacuum cleaner comprising the brushless permanent magnet motor according to the second aspect of the present invention.

[0023] According to a fifth aspect of the present invention, a stator core assembly for a stator core of a brushless permanent magnet motor is provided, the stator core assembly comprising a stator core segment spanning an arc length of approximately 120 degrees, and a coil wound around the stator core segment so that the coil covers the radial inner surface and the radial outer surface of the stator core segment.

[0024] Where appropriate, optional features of one aspect of the invention may be equally applicable to other aspects of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a perspective view of the stator assembly;

[0026] Figure 2 yes Figure 1 Exploded view of the stator assembly;

[0027] Figure 3 yes Figure 1 a perspective view of a stator core assembly of a stator assembly;

[0028] Figure 4 yes Figure 3 An exploded view of the stator core assembly;

[0029] Figure 5 yes Figure 1 a perspective view of a first busbar assembly of a stator assembly;

[0030] Figure 6 yes Figure 5 A perspective view of a live busbar of a first busbar assembly;

[0031] Figure 7 It is a perspective view of the neutral busbar;

[0032] Figure 8 is included Figure 1 Schematic diagram of a brushless permanent magnet motor having a rotor assembly;

[0033] Figure 9 is included Figure 6 A schematic diagram of a brushless permanent magnet motor of a vacuum cleaner; and

[0034] Figure 10 is included Figure 1 Schematic diagram of a hair care appliance with a brushless permanent magnet motor. DETAILED DESCRIPTION

[0035] The stator assembly 10 is Figure 1 and Figure 2 1 , and includes a first stator core assembly 12 , a second stator core assembly 14 , and a third stator core assembly 16 , as well as a first bus bar assembly 18 and a second bus bar assembly 20 .

[0036] The first stator core assembly is as follows Figure 3 and Figure 4 Each of the first stator core assembly 12, the second stator core assembly 14, and the third stator core assembly 16 has substantially the same form, and therefore, for the sake of brevity, the second stator core assembly 14 and the third stator core assembly 16 will not be described in detail herein. It should be understood that the same reference numerals used for features of the first stator core assembly 12 may be used for corresponding features of the second stator core assembly 14 and the third stator core assembly 16.

[0037] The first stator core assembly 12 includes a stator core segment 22 , a bobbin 24 , first 26 , second 28 , and third 30 terminal connections, and a first coil 32 and a second coil 34 .

[0038] The stator core segments 22 are formed from a stack of steel laminations (not shown) and are generally arcuate, with a height greater than both length and width. The stator core segments 22 span an arc length of approximately 120 degrees. The circumferential end faces of the stator core segments 22 are generally planar in form.

[0039] The bobbin 24 is formed of a plastic material and is overmolded to the stator core segment 22. The bobbin 24 includes a connection recess 36, a window 38, and a connection structure 40. The connection recess 36 is generally cylindrical in form and is shaped and sized to receive the corresponding first to third terminal connectors 26-30. The window 38 is generally elongated and rectangular in cross-section and provides a line of sight to the radially outer surface of the stator core segment 22. The window 38 enables appropriate magnets to hold the stator core segment 22 in place during assembly of the first stator core assembly 12. The connection structure 40 includes appropriate protrusions and / or recesses that interact with corresponding recesses and / or protrusions of the second stator core assembly 14 and the third stator core assembly 16 to hold the stator core assemblies 12, 14, 16 relative to each other.

[0040] The first through third terminal connectors 26-30 have substantially the same form and are typically elongated pins formed of a conductive material with a square cross-sectional shape. The first and second terminal connectors 26, 28 are inserted into corresponding connection recesses 36 by a push fit and extend axially outward from a first end 42 of the first stator core assembly 12. The third terminal connector 30 is inserted into the corresponding connection recess 36 and extends axially outward from a second end 44 of the first stator core assembly 12 opposite the first end 42 of the first stator core assembly 12.

[0041] The first and second coils 32, 34 are formed from multiple turns of copper wire and are wound around the bobbin 24 such that the first and second coils 32, 34 cover both the radially inner and radially outer surfaces of the stator core segments 22. The stator assembly 10 is a slotless stator assembly. For clarity, the first and second coils 32, 34 are shown in block form, making the individual turns invisible. The first and second coils 32, 34 are formed from a single piece of copper wire, allowing them to be wound using a continuous winding process. For example, the first coil 32, located at the first terminal connection 26, is wound around the bobbin 24, and thus around the stator core segments 22, and is then tied at the third terminal connection 30. The second coil 32 then begins at the third terminal connection 30, is wound around the bobbin 24, and thus around the stator core segments 22, and is then tied at the second terminal connection 28. The first coil 32 and the second coil 34 are wound in opposite directions, wherein one of the first coil 32 and the second coil 34 is wound in a right-handed manner, and the other of the second coil 34 and the first coil 32 is wound in a left-handed manner.

[0042] Collectively, the first, second, and third stator core assemblies 12, 14, and 16, when connected together, define an annular space having a central bore 46 for receiving the rotor assembly, wherein the stator assembly 10 has a diameter of no greater than 40 mm. When connected together, the generally circumferential surfaces of the stator core segments 22 substantially contact one another, such that a generally annular stator core is formed by the stator core segments 22. The first and second terminal connectors 26, 28 of each stator core assembly 12, 14, 16 form a first subset of terminal connectors located at a first end 48 of the stator assembly 10, and the third terminal connector 30 forms a second subset of terminal connectors located at a second end 50 of the stator assembly 10.

[0043] The first and second terminal connections 26 , 28 are evenly spaced around the circumference of the first end 48 of the stator assembly 10 , while the third terminal connections 30 are evenly spaced around the circumference of the second end 50 of the stator assembly 10 .

[0044] The first busbar assembly 18 is located at a first end 48 of the stator assembly 10 and is Figure 5 The first busbar assembly 18 includes a carrier 52 and three live busbars 54 .

[0045] The carrier 52 is generally annular in form and is molded from a plastic material. The carrier 52 includes three channels 56 and three heat stakes 58. Each channel 56 has a substantially identical form, is formed on the radially outer surface of the carrier 52, and has a central portion 60, an upper portion 62, and a lower portion 64. The central portion 60 extends axially along the height of the carrier 52, while the upper portion 62 extends circumferentially from the central portion 60 in a first direction, and the lower portion 64 extends circumferentially from the central portion 60 in a second direction opposite the first direction. The upper portion 62 of one channel 56 overlaps the lower portion 64 of an adjacent channel 56 on the carrier 52. Each heat stake 58 is located in the corresponding central portion 60 of the channel 56.

[0046] Live bus 54 Figure 6 5. The live busbar 54 is formed of an electrically conductive material and includes a central portion 66, an upper portion 68, and a lower portion 70. The central portion 66 extends axially in a height direction, while the upper portion 68 extends circumferentially from the central portion 66 in a first direction, and the lower portion 70 extends circumferentially from the central portion 66 in a second direction opposite the first direction. The central portion 66 defines a connection between the stator assembly 10 and an inverter (not shown), such as a live connection of the stator assembly that can receive a voltage during use. The central portion 66 includes a hole 72 for receiving a corresponding heat stake 58 of the carrier 52.

[0047] Each of the upper portion 68 and the lower portion 70 includes a connecting arm 74 extending in a direction parallel to the height of the middle portion 66. The connecting arms 74 are substantially evenly spaced apart from the middle portion 66. The connecting arms 74 are welded at the first end 48 of the stator assembly 10 to the first terminal connection 26 and the second terminal connection 28 of each stator core assembly 12, 14, 16. Each live bus bar 54 is thereby connected to two coils of the stator assembly.

[0048] The second busbar assembly 20 is located at the second end 50 of the stator assembly 10 and is Figure 7 16 . The second busbar assembly 20 includes a single neutral busbar having a main body 76 and three connecting arms 78. The main body 76 is arcuate, and the three connecting arms 78 extend from the main body 76. The connecting arms 78 are welded to the third terminal connection 30 of each stator core assembly 12, 14, 16 at the second end 50 of the stator assembly 10. Assuming that the first coil 32 and the second coil 34 of each stator core assembly 12, 14, 16 are connected to the third terminal connection 30 of that particular stator core assembly 12, 14, 16, and that a single neutral busbar is used to connect the third terminal connections 30 together, each first coil 32 and second coil 34 of the stator assembly is connected together by the second busbar assembly 20.

[0049] In the manner described above, coils 32 , 34 and first and second busbar assemblies 18 , 20 define a three-phase parallel star connection with first and second terminal connections 26 , 28 serving as live connections and third terminal connection 30 serving as neutral connection.

[0050] Positioning the first and second terminal connections 26, 28 at the opposite end of the stator assembly 10 from the third terminal connection 30 can enable the stator assembly 10 to have a smaller radial and / or axial dimension than a stator assembly having terminal connections located at a single end of the stator assembly. By minimizing the radial and / or axial dimension of the stator assembly, the size of the brushless permanent magnet motor including the stator assembly 10 can be minimized, which can provide a minimized packaging volume for the brushless permanent magnet motor within an appliance.

[0051] Furthermore, positioning the terminal connectors at opposite ends of the stator assembly 10 in this manner may facilitate manufacture of the stator assembly 10 by providing more space for accessing the terminal connectors compared to an arrangement where all terminal connectors are located at a single end of the stator assembly 10 .

[0052] The manufacture of the stator assembly 10 can be further facilitated by using three stator core segments 22, each of which spans an arc length of approximately 120 degrees. In particular, segmenting the stator core can enable the stator core segments 22 to be more linear than would be the case if a smaller number of segments were used to form an annular stator core. This can facilitate the formation of the laminations that form the stator core segments 22, for example by enabling an increased number of laminations to be formed from a single piece of material, thereby reducing material waste and cost.

[0053] Furthermore, a toroidal core or two-part core with each segment spanning an arc length of 180 degrees provides a winding machine with reduced access to the interior of the bend defined by the stator core segments when compared to, for example, a bend with a shorter arc length. The shorter arc length stator core segments can enable the use of an easier and / or less expensive winding process.

[0054] In use, the stator assembly 10 is mated with the rotor assembly 100 to form a brushless permanent magnet motor 102, such as Figure 8 The rotor assembly 102 includes a shaft 104 and permanent magnets 106 mounted to the shaft 104. When the coils 32, 34 are driven at an appropriate voltage (here up to about 400 V), the stator assembly 10 generates a magnetic field that interacts with the permanent magnets 106 to rotate the rotor assembly 100.

[0055] exist Figure 9 A vacuum cleaner 200 comprising a brushless permanent magnet motor 102 is schematically shown in FIG.

[0056] exist Figure 10 A hair care appliance 300 including a brushless permanent magnet motor 102 is schematically shown in FIG.

Claims

1. A stator assembly for a brushless permanent magnet motor, the stator assembly comprising: a first stator core assembly, a second stator core assembly, and a third stator core assembly, each of the first stator core assembly, the second stator core assembly, and the third stator core assembly including a stator core segment and a coil wound around the stator core segment; Each stator core segment spans an arc length of approximately 120 degrees, each coil is wound around a corresponding stator core segment such that the coil covers a radially inner surface and a radially outer surface of the stator core segment, and the coils are connected such that the stator assembly comprises a three-phase stator assembly.

2. The stator assembly according to claim 1, wherein: Each of the first, second, and third stator core assemblies includes a first coil and a second coil, such that the stator assembly includes a total of six coils.

3. The stator assembly according to claim 2, wherein: The first coil and the second coil of each respective stator assembly are wound in opposite directions.

4. The stator assembly according to claim 2 or 3, wherein: The first coil and the second coil of each respective stator assembly are wound using a single wire.

5. A stator assembly according to any one of the preceding claims, wherein: Each of the first stator core assembly, the second stator core assembly and the third stator core assembly includes a corresponding bobbin, each bobbin includes a first connection structure and a second connection structure, and the first connection structure and the second connection structure are connected to the corresponding second connection structure and first connection structure of the adjacent stator core assembly of the first stator core assembly, the second stator core assembly and the third stator core assembly in the stator assembly.

6. A stator assembly according to any one of the preceding claims, wherein: Each of the stator core segments includes a generally flat first end surface and a second end surface, and the generally flat first end surface and the second end surface contact the corresponding generally flat second end surface and first end surface of the adjacent stator core components of the first stator core component, the second stator core component and the third stator core component in the stator assembly.

7. A stator assembly according to any one of the preceding claims, wherein: The stator assembly has an outer diameter no greater than 40 mm.

8. A stator assembly according to any one of the preceding claims, wherein: Each stator core assembly includes the same number of terminal connections to which the corresponding coils are connected.

9. A stator assembly according to any one of the preceding claims, wherein: Each of the first stator core assembly, the second stator core assembly, and the third stator core assembly comprises substantially the same form.

10. A brushless permanent magnet electric machine comprising a stator assembly according to any one of the preceding claims.

11. A hair care appliance comprising the brushless permanent magnet motor according to claim 10. 12 . A vacuum cleaner comprising the brushless permanent magnet motor according to claim 10 .

13. A stator core assembly for a stator core of a brushless permanent magnet motor, comprising a stator core segment spanning an arc length of approximately 120 degrees, and a coil wound around the stator core segment such that the coil covers a radially inner surface and a radially outer surface of the stator core segment.

Images