Claims:We claim:
1. A stator core assembly comprising:
a. a plurality of stator poles (101), wherein the stator poles (101) are assembled and segmented in circular cross-section, wherein each stator pole segment is tightly winded with a plurality of copper wires;
b. an aluminum housing (102), wherein the aluminum housing (102) is heated and fitted with the stator pole segments therein, wherein the stator pole segments are tightly held inside the aluminum housing (102) after cooling thereof and thereby forming a stator core (100); and
c. a rotor with a plurality of magnets housed and assembled inside the stator pole segments.

2. The assembly as claimed in claim 1, wherein the coefficient of linear expansion of the aluminum housing (102) is greater than the coefficient of linear expansion of the stator poles (101).

3. The assembly as claimed in claim 1, wherein the coefficient of linear expansion of the aluminum housing (102) section and the coefficient of linear expansion of the stator poles (101) are selected such that an amount of shrinkage of the stator poles (101) is equal to an amount of shrinkage of the aluminum housing (102) section.

4. The assembly as claimed in claim 1, wherein each stator pole (101) segment is made separately.

5. The assembly as claimed in claim1, wherein the assembly (100) further comprises of a helical bush, which is attached to the aluminum housing using a steel pin through one or more side holes therein.

6. A process to integrate the stator core assembly using shrink fitting, the process comprising the steps of:
a. making a plurality of stator poles (201);
b. segmenting and assembling the stator poles in circular cross-section (202);
c. arranging the plurality of segment poles is in circular cross -section (203);
d. heating an aluminum housing (204);
e. assembling and fitting the stator poles inside the heated aluminum housing (205); and
f. forming a stator core assembly after cooling the aluminum housing thereof (206).
, Description:[0001] Preamble to the Description
[0002] The following specification particularly describes the invention and the manner in which it is to be performed:
[0003] Description of the invention:
[0004] Technical field of the invention
[0005] The present invention relates to a stator core assembly using shrink fitting process. More particularly, the stator core assembly prevents the wastage of raw materials during manufacturing process and also eliminates stress on the stator segment poles during operating conditions.
[0006] Background of the invention
[0007] A rotating electric machine is provided with a plurality of stator cores which are connected with each other in a circular orientation. Generally, the electric motors have an inner rotor arranged at the center of a stator core and held by a chassis. The stator core includes the stator core segments, that are arranged in the circumferential direction of the stator core to adjoin one another in the circumferential direction. Further, to reduce iron loss of the stator core, each of the stator core segment is formed by laminating a plurality of magnetic steel sheets in the axial direction of the stator core. Moreover, the stator core has the slots that are formed in the radially inner surface of the stator core. The stator coil is mounted on the stator core and stator coil is received in the slots of the stator core. The outer cylinder is fitted on the radially outer surfaces of the stator core segments to fasten them together. The stator lamination core pack is blanked from lamination sheets and is stacked or welded or riveted.
[0008] Various types conventional methods for assembling the stator core are known in the prior art. The EP Patent document 2651011 A2 describes anon-vehicle rotary electric machine and electric power steering system. In the cited document, an electrical motor includes a cylindrical stator core arranged so as to surround a periphery of a rotor via a space, and having a plurality of teeth formed in an inner periphery thereof; a bobbin installed in each of the plurality of teeth; a coil wound around each of the bobbins installed in the teeth; a bottomed cylindrical chassis having a bottom faced with one of end portions in the axial direction of the stator core, and holding an outer periphery of the stator core; and a bus-bar mold provided with a bus-bar terminal. An engaging hole is formed at least in either the bottom or the bus-bar mold at a position facing the bobbin, and an engaging projection that engages with the engaging hole is formed in an opposing part that faces the engaging hole in the bobbin.
[0009] The United States Patent document 6570277 B2 describes a rotating electric machine. In the cited document, the rotating electric machine is provided with a plurality of stator cores connected with each other in a circular orientation. A cooling passage is provided which is defined by two adjacent stator cores and a circular resin mold which closes the slot openings. In this type of rotating electric machine, there is the possibility of leakage of cooling medium as a result of cooling shrinkage in the resin mold.
[0010] Typically, the claimed conventional system and method uses a blanking process in the sheets to manufacture the full stator lamination core to the required profile. Here, the laminations are staked and riveted for a desired length. Typically, during the blanking process of stator lamination core in the sheets, the center portion and slot portion of the stator lamination core is wasted. Conventional steel housing for the stator core requires high temperature for shrink fitting. Due to high temperature, the steel surface coating may damage and increases the possibility of corrosion. Typically, the stress developed on the stator segment poles is more and leads to more core loss.
[0011] Hence, there is a need for a stator core assembly, which requires fewer raw materials to manufacture. More particularly, the stator core assembly prevents the wastage of raw materials during manufacturing process and also eliminates stress on the stator segment poles during operating conditions.
[0012] Summary of the invention:
[0013] The present invention overcomes the drawbacks in the prior art and provides a stator core assembly using shrink fitting process. In a preferred embodiment, the assembly comprises a plurality of stator poles, wherein the stator poles are assembled and segmented in circular cross-section. An aluminum housing is heated and fitted with the stator pole segments therein. The stator pole segments are tightly held inside the aluminum housing after cooling thereof and thereby forming a stator core. A rotor with a plurality of magnets are housed and assembled inside the stator pole segments.
[0014] In preferred embodiment of the invention, the coefficient of linear expansion of the aluminum housing is greater than the coefficient of linear expansion of the stator core.
[0015] In preferred embodiment of the invention, the coefficient of linear expansion of the aluminum housing section and the coefficient of linear expansion of the stator core are selected such that an amount of shrinkage of the stator core is equal to an amount of shrinkage of the aluminum housing section.
[0016] In preferred embodiment of the invention, each stator pole segment is made separately.
[0017] In another embodiment of the invention, the process includes the steps of making a plurality of stator poles. After making the stator poles, the stator poles are segmented and assembled in a circular cross-section. The plurality of segment poles is arranged in circular cross -section. After arranging, an aluminum housing is heated. After heating the aluminum housing, the stator poles are assembled and fitted inside the heated aluminum housing. Finally, a stator core assembly is formed after cooling the aluminum housing thereof.
[0018] The present invention provides a stator core assembly, which prevents the wastage of raw materials (i.e. the center portion and slot portion of the stator lamination core) during manufacturing process and also eliminates stress on the stator segment poles during operating conditions.
[0019] The present invention provides a stator core assembly which is simple, cost effective and easy to assemble and is suitable for the applications in all types of motor manufacturing industries.
[0020] It is to be understood that both the foregoing general description and the following details description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
[0021] Brief description of the drawings:
[0022] The foregoing and other features of embodiments will become more apparent from the following detailed description of embodiments when read in conjunction with the accompanying drawings. In the drawings, like reference numerals refer to like elements.
[0023] Figure 1 shows a perspective view of the individual stator pole, according to one embodiment of the invention.
[0024] Figure 2 shows a perspective view of the stator pole, according to one embodiment of the invention.
[0025] Figure 3 shows a perspective view of the stator core assembly, according to one embodiment of the invention.
[0026] Figure 4 illustrates the process involved in integrating the stator core assembly using shrink fitting, according to one embodiment of the invention.
[0027] Detailed description of the invention:
[0028] Reference will now be made in detail to the description of the present subject matter, one or more examples of which are shown in figures. Each example is provided to explain the subject matter and not a limitation. Various changes and modifications obvious to one skilled in the art to which the invention pertains are deemed to be within the spirit, scope and contemplation of the invention.
[0029] The present invention provides a stator core assembly, which prevents the wastage of raw materials (i.e. the center portion and slot portion of the stator lamination core) during manufacturing process and also eliminates stress on the stator segment poles during operating conditions.
[0030] Figure 1 shows a perspective view of the individual stator pole, according to one embodiment of the invention. In a preferred embodiment, the stator core includes a plurality of stator poles. Here, each stator pole is made separately. The stator poles are assembled and segmented in circular cross-section.
[0031] Figure 2 shows a perspective view of the stator pole, according to one embodiment of the invention. In a preferred embodiment, each stator pole is made separately. The stator poles are assembled and segmented in circular cross-section.
[0032] Figure 3 shows a perspective view of the stator core assembly, according to one embodiment of the invention. In a preferred embodiment, the stator assembly includes a plurality of stator poles, an aluminum housing and a rotor with a plurality of magnets. The stator poles are assembled and segmented in circular cross-section. The aluminum housing is heated and fitted with the stator pole segments therein. The stator pole segments are tightly held inside the aluminum housing after cooling thereof and thereby forming a stator core. The rotor is housed and assembled inside the stator core and thereby forming a Brushless DC (BLDC) motor.
[0033] In another embodiment, the stator assembly is further provided with a stationary helical bush. The helical bush is attached to the aluminum housing using a steel pin through two side holes therein. The side holes are drilled and easy to manufacture in the aluminum housing than in the laminated stator core. The holes are necessary for giving support for the steel pin. The stationary helical bush provides the oil circulation at low speed to save energy when the cooling demand is less. The aluminum housing is further provided with an additional hole for supporting the assembly of oil circulation pipes.
[0034] Figure 4 illustrates the process involved in integrating the stator core assembly using shrink fitting, according to one embodiment of the invention. In a preferred embodiment, the process includes the steps of making a plurality of stator poles, at step (201). After making the stator poles, the stator poles are segmented and assembled in a circular cross-section, at step (202). At step (203), the plurality of segment poles is arranged in circular cross -section. An aluminum housing is heated, at step (204). After heating the aluminum housing, the stator poles are assembled and fitted inside the heated aluminum housing, at step (205). Finally, at step (206), a stator core assembly is formed after cooling the aluminum housing thereof.
[0035] The present invention provides a stator core assembly, which prevents the wastage of raw materials (i.e. the center portion and slot portion of the stator lamination core) during manufacturing process and also eliminates stress on the stator segment poles during operating conditions.
[0036] The present invention provides a stator core assembly which is simple, cost effective and easy to assemble and is suitable for the applications in all types of motor manufacturing industries.