This non-provisional patent application claims priority under 35 U.S.C. §119(a) from Patent Application No. 201510054879.2. filed in The People's Republic of China on Jan. 30, 2015, and from Patent Application No. 201510738743.3 filed in The People's Republic of China on Nov. 3, 2015, the entire contents of both are hereby incorporated by reference.
This invention relates to an electric motor and in particular, to a motor having a wound. stator core.
Electric motors are a common source of mechanical power, being used in a wide variety of applications and devices, such as electric fans, washing machines, water pumps etc. Generally, a motor is composed of two parts, namely a rotor and a stator. A one type of motor, the stator is composed of a magnetic core with windings wound around the magnetic core. The rotor may have a permanent magnet. When energized, the windings of the stator generate a magnetic field which interacts with a magnetic field of the rotor to rotate the rotor and in turn drive a load.
The magnetic core of a known wound stator is generally formed by stacking a large number of silicon steel sheets or laminations. Each silicon steel sheet is formed by directly punching a thin sheet material. Each silicon steel sheet comprises an annular yoke, and teeth radiating from the yoke part. For a stator used in an outer rotor motor, the teeth radiate outwardly from the yoke. An annular supporting part is formed at a central area of the yoke. The supporting part is used to fixedly connect the stator to other components. The windings are wound around the teeth. Although the manufacturing procedure of the stator core of the existing stator is simple, the punching process use to form the stator laminations generates a large amount of waste material, resulting in a high cost.
Hence there is a desire for a motor with a stator having better rate of material utilization.
Accordingly, in one aspect thereof, the present invention provides a motor comprising: a support seat, a stator structure and a rotor, wherein the rotor is rotatably mounted on the support seat, and the stator structure comprises: a core, a winding frame covering the core, and windings wound around the winding frame, the core includes a ring-shaped yoke and a plurality of teeth extending outwardly from the yoke, the winding frame comprises an insulating part covering the core and a connecting part within the insulating part to fixedly connect to the support seat.
Preferably, each tooth includes a winding portion connected with the yoke and a tip formed at a distal end of the winding portion, the windings are wound around the winding portions, a notch is formed in a connection area between the tip and the winding portion, the tip is partially tilted outwardly before the winding is completed and is pressed to bend inwardly to contact the winding portion after the winding is completed.
Preferably, the core is formed by bending material strips, the yoke of the core has through holes, and fastening members are inserted into the through holes to fix the material strips together.
Preferably, the core is formed by bending material strips, and tips of the core are welded to fixed the strips together.
Preferably, the support seat is formed from a thermally conductive material.
Preferably, cooling fins are provided on a side of the support seat facing the stator structure.
Preferably, one side of the support seat remote from the stator structure forms a receiving cavity, and a circuit board is received in the receiving cavity.
Preferably, the connecting part comprises a ring-shaped base plate extending integrally and radially inwardly from the insulating part, a hollow cylinder extending integrally and axially from an inner edge of the base plate, and a plurality of ribs connected between an outer wall surface of the hollow cylinder and an inner wall surface of the insulating part.
Preferably, the base plate of the winding frame has through holes, the support seat is provided with fixing posts corresponding to the through holes, and fixing members pass through the through holes and are fastened in the fixing posts.
Preferably, the winding frame is an over-molded integrated structure, the fixing members are integrally fixed at the through holes of the winding frame during the course of forming the winding frame, and distal ends of the fixing members pass through the support seat to connect the stator structure with the support seat.
Preferably, the support seat is provided with a positioning post, a step is formed at a top end of the positioning post, the base plate has a positioning hole corresponding to the positioning post, the top end of the positioning post is inserted into the positioning hole, and the stator structure is disposed on the step of the positioning post.
Preferably, one of an inner wall surface of the hollow cylinder of the winding frame and an outer wall surface of the sleeve of the support seat forms a protrusion, and the other forms a recess for engaging with the protrusion to circumferentially position the stator structure.
Preferably, the insulating part is ring-shaped, the connecting part comprises a plurality of connecting lugs extending inwardly from the ring-shaped insulating part, each connecting lug forms a through hole, the support seat forms a plurality of fixing holes corresponding to the through holes of the winding frame, and fixing members pass through the through holes and are fastened in the fixing holes, respectively, to fix the stator to the support seat.
Preferably, the core has connecting arms extending inwardly from the ring-shaped yoke, the connecting part of the winding frame includes connecting lugs extending inwardly from the insulating part, the connecting lugs and the connecting arms correspond respectively and form coaxial through holes, the support seat forms a plurality of fixing holes, and fixing members pass through the through holes and are fastened in the fixing holes of the support seat, respectively.
In comparison with the conventional magnetic core, the winding frame of the present invention integrally forms the connecting part within the core to fixedly connect with the support seat, which saves material and reduces the weight of the stator structure and the motor.
A preferred embodiment of the invention will now be described, by way of example only, with reference to figures of the accompanying drawings. In the figures, identical structures, elements or parts that appear in more than one figure are generally labeled with a same reference numeral in all the figures in which they appear. Dimensions of components and features shown in the figures are generally chosen for convenience and clarity of presentation and are not necessarily shown to scale. The figures are listed below,
Referring to
A center of the support seat 10 protrudes axially upwardly to form a hollow sleeve 12, and the hollow sleeve 12 is used to support a bearing or the like for supporting rotation of the rotor. An outer wall surface of a top of the sleeve 12 protrudes outwardly to form a protrusion 14, for engaging with and positioning the stator structure 20 circumferentially. The protrusion 14 is preferably cylindrical. The support seat 10 is further provided with fixing posts 16 and positioning posts 18. In this embodiment, there are two fixing posts 16 and two positioning posts 18, which surround the sleeve 12 and are alternately arranged in a circumferential direction of the sleeve 12. Each fixing post 16 is formed with a fixing hole 17 therein. The fixing hole 17 may be a round hole or a screw hole for fixed connection with the stator structure 20. A top end of each positioning post 18 is formed with a step 19 for pre-positioning the stator structure 20 in the axial direction. Preferably, the positioning post 18 is slightly higher than the fixing post 16, and the step 19 and a top surface of the fixing post 16 are located on substantially the same level.
The stator structure 20 comprises a core 22 made of a soft magnetic material, an insulating winding frame 24 wrapped over the core 22, and windings 25 wound around the core 22.
In this embodiment, the core 22 is of an integrated structure formed by spirally stacking and winding a strip material (i.e. formed by continuously spirally winding the strip material), including an annular yoke 26 and a plurality of teeth 28 that extend radially outwardly from an outer edge of the yoke 26 The yoke 26 is of a hollow cylindrical structure formed by the spiral winding of the strip material. The teeth .8 are uniformly (non-uniformly in some embodiments) disposed at intervals in a circumferential direction of the yoke 26. Compared with the traditional circular punching sheet structure, the spirally stacked and wound core 22 generates significantly less waste material, thereby improving the utilization rate of raw materials. In some embodiments, the strip materials can also be bent to form circular sheets, and the circular sheets are stacked in the axial direction of the motor to form the core 22, which likewise generates substantially less waste material. In this embodiment, a plurality of through holes 27 is formed in the yoke 26. The through holes 27 may be formed by stacking small holes in the strip materials, which are arranged uniformly (non-uniformly in some embodiments) in the circumferential direction of the yoke 26. Each through hole 27 penetrates axially through the yoke 26, and a fastening member, such as a rivet 30, passes through the through hole 27 to shape the core 22. In some embodiments, the core 22 can be shaped in other manners, such as, for example, by fixedly connecting tips 34 of the stacked teeth 14 by welding.
Each tooth 28 includes a winding portion 32 connected with the yoke 26 and a tip 34 formed at a distal end of the winding portion 32. The tip 34 extends in the circumferential direction of the motor. A winding slot 36 is formed between adjacent winding portions 32, a slot opening 38 is formed between adjacent tips 34, and the windings are wound around the winding portions 32 and disposed in the winding slots 36. Preferably, a notch 33 is formed in a connection area of the tip 34 and the winding portion 32. Before formation, the tip 34 is partially tilted outwardly, and the slot opening 38 between the adjacent tips 34 has a large size for facilitating winding. After winding is completed, the tilted part of the tip 34 is pressed to generate plastic deformation to bend inwardly, such that a root of the tip 34 is in tight contact with the winding portion 32, and a small slot opening is formed between the adjacent tips 34 to reducing cogging torque of the motor. In this embodiment, the notch 33 is only formed in a connection area of the tip 34 and in a single side of the winding portion 32. Of course, in other embodiments, the notch 33 can be formed in the connection area of the tip 34 and each side of the winding portion 32.
Referring to
The base plate 44 is circular ring shaped. As shown in
As shown in
The fixing members 50 may be screws, rivets or the like. When the fixing members 50 are rivets, the fixing members 50 may be integrally fixed on the winding frame 24 during the course of forming the winding frame 24, and the fixing holes 17 are round holes passing through the fixing posts 16. In assembly, the distal ends of the fixing members 50 pass through the fixing posts 16 and are then deformed to fixedly connect the stator structure 20 with the support seat 10. When the fixing members 50 are screws, a metal piece such as a metal sleeve may be disposed in each through hole 45 when forming the winding frame 24, which prevents the winding frame 24 from being damaged during assembly.
Referring to
It is to be understood that the support seat 10 may be formed from a thermally conductive material such as aluminum. As such, the support seat 10 can also provide the heat dissipating function. After the stator structure is mounted to the sleeve 12, a free end of the sleeve 12 extends outward beyond a free end of the hollow cylinder 46. The free end of the sleeve 12 is then sealed by a tool having an arc-shaped machining surface, such that the free end of the sleeve 12 generates an outward plastic deformation thus forming a rivet connection with the stator structure. That is, an outer surface of the free end of the sleeve 12 is deformed to press against an edge of the hollow cylinder 46 of the stator structure to prevent the hollow cylinder 46 from becoming disengaged from the free end of the sleeve 12. As such, the fixing members 50 can be omitted.
In the stator structure 20 of the present invention, the stator core 22 is formed by bending or winding the strip material, which enhances the material utilization rate and reduces the cogging torque, thus improving the operational stability of the motor. In addition, by forming the integrated winding frame 24 with the over-molding process, the winding frame 24 integrally forms the hollow cylinder 46 within the core 22 to connect with the support seal 10. In comparison with the conventional stator core which has the central connecting portion connected with the support seat 10, the core 22 of the present invention saves material and reduces the weight of the stator structure 20 and the motor by forming the winding frame 24 from plastic and connecting the hollow cylinder 46 and the insulating part 42 with the ribs 48,
In the description and claims of the present application, each of the verbs “comprise”, “include”, “contain” and “have”, and variations thereof, are used in an inclusive sense, to specify the presence of the stated item or feature but do not preclude the presence of additional items or features.
It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.
The embodiments described above are provided by way of example only, and various other modifications will be apparent to persons skilled in the field without departing from the scope of the invention as defined by the appended claims.
Number | Date | Country | Kind |
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201510054879.2 | Jan 2015 | CN | national |
201510738743.3 | Nov 2015 | CN | national |