Insulator for insulating coils of a stator of electric motor

A stator capable of preventing the displacement of insulators and securely positioning the insulators at given positions. A stator includes a stator core formed with slots; a coil wound around the stator core, the coil comprising a coil side and a coil end, the coil end arranged outside the slot; and insulators provided in the slots. Each insulator includes a coil side-insulation part arranged between wall surfaces of a slot and a first coil side and electrically insulating the wall surfaces from the first coil side; and a coil end-insulation part formed in one piece with the coil side-insulation part and arranged outside the first slot. The coil end-insulation part is arranged between a first coil end and a second coil end and electrically insulates the first coil end from the second coil end.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to stators of electric motors.

2. Description of the Related Art

Stator cores have coils that are wound around them and received in slots defined in the stator cores. Conventionally, insulators are used for insulating coils from slot wall surfaces or for insulating coils connected to different lines (e.g., U, V, and W lines) from each other (see e.g., Japanese Unexamined Patent Publication (Kokai) No. 2004-072899 and Japanese Unexamined Patent Publication (Kokai) No. 2012-034453).

There has been a demand of techniques for preventing insulators of such motors as described above from being displaced and for securely positioning the insulators at given positions.

SUMMARY OF THE INVENTION

A stator of an electric motor comprises a stator core formed with a plurality of slots; a coil wound around the stator core, and including a coil side received in one of the slots and a coil end arranged outside of the slot; and a plurality of insulators, each of which is arranged in each of the plurality of slots.

Each insulator includes a coil side-insulation part arranged between a wall surface(s) of a first slot of the plurality of slots, in which the insulator is arranged, and a first coil side received in the first slot, the coil side-insulation part electrically insulating the first coil side from the wall surface(s); and a coil end-insulation part integrally coupled with the coil side-insulation part, and arranged outside of the first slot.

The coil end-insulation part is arranged between a first coil end of a first coil including the first coil side and a second coil end of a second coil including a second coil side received in a second slot of the plurality of slots different from the first slot, the coil end-insulation part electrically insulating the first coil end from the second coil end.

Each insulator may be a seamless one-piece member. The coil end-insulation parts of two adjacent insulators may be arranged so as to overlap each other. The stator may further comprise a connection part configured to connect the coil end-insulation parts of two adjacent insulators. In another aspect of the invention a motor comprises the above-described stator.

DETAILED DESCRIPTION

Embodiments of the invention will be described below in detail with reference to the drawings. Note that, in the following embodiments, similar elements are assigned the same reference numerals, and detailed descriptions thereof will be omitted.

First, referring toFIGS. 1-4, a stator10according to an embodiment will be described. The stator10is cylindrical, and constitutes a motor together with a rotor (not shown) which is rotatably supported radially inside of the stator10.

In the description of this embodiment, the axial direction corresponds to a direction along the central axis of the stator10(i.e., along the arrow A in the drawings), the radial direction corresponds to a radial direction of a circle centered about the central axis of the stator10, and the circumferential direction corresponds to a circumferential direction of the circle. For convenience, the direction indicated by the arrow A is referred to as the upward in the axial direction (or axially upward).

The stator10includes a stator core12, a coil14, a coil16, insulators18, insulators20, insulators22, and insulators24. The stator core12includes a ring-shaped back yoke26(FIG. 2), a plurality of teeth28projecting radially inward from the back yoke26. Each tooth28is formed with protrusions28aprotruding to both sides in the circumferential direction from the radially inner end of the tooth28.

The stator core12is formed with a plurality of slots30formed to align in the circumferential direction. Note that, inFIGS. 1 and 2, a total of six slots30ato30fof the plurality of slots30are shown.

Each of the slots30is formed to open to radially inside. In particular, each of the slots30is defined by an inner wall surface32of the back yoke26, a side wall surface34of one tooth28in one direction of the circumferential direction, a side wall surface36of another tooth28, which is adjacent to the one tooth28in the one direction of the circumferential direction, in the other direction of the circumferential direction, and inner wall surfaces28bof two opposing protrusion28a.

The coil14and the coil16are wound around the stator core12. In this embodiment, the coil14and the coil16are different transmission lines for transmitting alternating current signals of different phases of a three-phase alternating current (e.g., U and V lines, V and W lines, or U and W lines). InFIGS. 1 and 2, the coil14is wired so as to pass through the slots30a,30b, and30c, respectively.

The coil14includes coil sides14arespectively received in the slots30a,30b, and30c, and coil ends14bconnected to the coil sides14aand extending outward from the slots30a,30b, and30cat both axial sides of the stator core12. Note that, inFIG. 1, only the coil ends14bextending axially upward from the slots30a,30b, and30care shown.

The coil16is wired so as to pass through the slots30d,30e, and30f, respectively. The coil16includes coil sides16arespectively received in the slots30d,30e, and30f, and coil ends16bconnected to the coil sides16aand extending outward from the slots30d,30e, and30fat both axial sides of the stator core12.

InFIG. 1, only the coil ends16bextending axially upward from the slots30d,30e, and30fare shown. In this embodiment, the coil ends14bof the coil14are wired so as to be arranged radially inside of the coil ends16bof the coil16.

Each of the insulators18is arranged in each of the slots30a,30b, and30c. Each insulator18is a seamless one-piece member. Here, a “seamless one-piece member” means a single monolithic member which is not produced by coupling a plurality of strips by e.g. adhesion. The insulator18is made of e.g. a paper or resin material.

As shown inFIG. 3, the insulator18includes a coil side-insulation part38, a coil end-insulation part40, and a coil end-insulation part42. The coil side-insulation part38has a substantially U-shaped cross-section, and includes a bottom38aand sides38band38cextending from both ends of the bottom38ain the circumferential direction so as to oppose to each other.

The coil side-insulation part38has a circumferential direction width W1and an axial direction length L1. In this embodiment, the circumferential direction width W1is set to be equal to or smaller than the circumferential direction width of the slots30a,30b, and30c. The axial direction length L1is set to be equal to or greater than the axial direction length of the slots30a,30b, and30c.

The coil end-insulation part40is integrally coupled with an axially upper end38dof the coil side-insulation part38, and extends axially upward from the coil side-insulation part38. The coil end-insulation part42is integrally coupled with an axially lower end38eof the coil side-insulation part, and extends axially downward from the coil side-insulation part38.

The coil end-insulation parts40and42respectively have circumferential direction widths W2and W2′, and axial direction lengths L2and L2′. The circumferential direction widths W2and W2′ may be the same or different. Similarly, the axial direction lengths L2and L2′ may be the same or different.

In this embodiment, circumferential direction widths W2and W2′ are set to be greater than the circumferential direction width of the slots30a,30b, and30c. As described below, the axial direction lengths L2and L2′ are set to be long enough to insulate the coil ends14bfrom the coil ends16b.

As shown inFIG. 2, when the insulators18are respectively arranged in the slots30a,30b, and30c, the bottom38aof the coil side-insulation part38of one insulator18is arranged between the coil side14aof the coil14and the inner wall surface32which defines the slot30a,30bor30c, and electrically insulates the coil side14afrom the inner wall surface32.

Further, the side38bof the coil side-insulation part38is arranged between the coil side14aand the side wall surface34which defines the slot30a,30bor30c, and insulates the coil side14afrom the side wall surface34.

Further, the side38cof the coil side-insulation part38is arranged between the coil side14aand the side wall surface36which defines the slot30a,30bor30c, and insulates the coil side14afrom the side wall surface36.

In this way, the coil side14areceived in the slot30a,30bor30cis surrounded by the bottom38aand sides38band38cof the coil side-insulation part38from both sides in the circumferential and from radially outside, so as to be insulated from the wall surfaces32,34and36which define the slot30a,30bor30c.

On the other hand, as shown inFIG. 1, the coil end-insulation part40of one insulator18extends axially upward from the stator core12to the outside of the slot30a,30bor30c. The coil end-insulation part40is arranged between the coil end14bof the coil14and the coil end16bof the coil16wired axially upward of the slot30a,30bor30c, and electrically insulates the coil end14bfrom the coil end16b.

Accordingly, the axial direction length L2of each coil end-insulation part40is set to be long enough to electrically insulate the coil end14bfrom the coil end16b. For example, the axial direction length L2is set so that the axially upper end of each coil end-insulation part40can be positioned axially upward of the axially upper ends of the coil ends14band16b.

Further, as shown inFIG. 1, the coil end-insulation parts40of two insulators18adjacent to each other in the circumferential direction are arranged so as to overlap each other in the radial direction. Accordingly, the circumferential direction width W2of the coil end-insulation parts40is set to be wide enough to allow the two coil end-insulation parts40adjacent to each other in the circumferential direction to overlap each other, in the state shown inFIG. 1.

Similarly to the coil end-insulation parts40, the coil end-insulation part42of one insulator18extends axially downward from the stator core12to the outside of the slot30a,30bor30c. The coil end-insulation part42is arranged between the coil end14bof the coil14and the coil end16bof the coil16at axially downside of the stator core12, and electrically insulates the coil end14bfrom the coil end16b.

Each of the insulators20is arranged in each of the slots30d,30e, and30f. Similarly to the insulator18, each insulator20is a seamless one-piece member. The insulator20is made of e.g. a paper or resin material.

As shown inFIG. 4, the insulator20includes a coil side-insulation part44, a coil end-insulation part46, and a coil end-insulation part48. The coil side-insulation part44has a shape similar as the above-mentioned bottom38a. In particular, the coil side-insulation part44has a circumferential direction width W3and an axial direction length L3.

In this embodiment, the circumferential direction width W3is set to be equal to or smaller than the circumferential direction width of the slots30d,30e, and30f. The axial direction length L3is set to be equal to or greater than the axial direction length of the slots30d,30e, and30f.

The coil end-insulation part46is integrally coupled with an axially upper end44aof the coil side-insulation part44, and extends axially upward from the coil side-insulation part44. The coil end-insulation part48is integrally coupled with an axially lower end44bof the coil side-insulation part44, and extends axially downward from the coil side-insulation part44.

The coil end-insulation parts46and48respectively have circumferential direction widths W4and W4′, and axial direction lengths L4and L4′. The circumferential direction widths W4and W4′ may be the same or different. Similarly, the axial direction lengths L4and L4′ may be the same or different.

In this embodiment, the circumferential direction widths W4and W4′ are set so as to be greater than the circumferential direction width of the slots30d,30e, and30f. As described below, the axial direction lengths L4and L4′ are set to be long enough to insulate the coil ends14bfrom the coil ends16b.

As shown inFIG. 2, when the insulators20are respectively arranged in the slots30d,30e, and30f, the coil side-insulation part44of one insulator20is arranged between the coil side16aof the coil16and the inner wall surfaces28bof two opposing protrusions28a, and electrically insulates the coil side16afrom the inner wall surfaces28b.

Along with this, the coil side-insulation part44seals the radially inside opening of the slot30d,30eor30f. Due to this, the coil side-insulation part44prevents the coil side16afrom dropping off from the slot30d,30eor30f.

On the other hand, as shown inFIG. 1, the coil end-insulation part46of one insulator20extends axially upward from the stator core12to the outside of the slots30d,30eor30f. The coil end-insulation part46is arranged between the coil end16bof the coil16and the coil end14bof the coil14wired axially upward of the slot30d,30eor30f, and electrically insulates the coil end16bfrom the coil end14b.

Accordingly, the axial direction length L4of each coil end-insulation part46is set to be long enough to electrically insulate the coil ends16bfrom the coil ends14b. For example, the axial direction length L4is set so that the axially upper end of each coil end-insulation part46can be positioned axially upward of the axially upper ends of the coil ends14band16b.

Further, as shown inFIG. 1, the coil end-insulation parts46of two insulators20adjacent to each other in the circumferential direction are arranged so as to overlap each other in the radial direction. Accordingly, the circumferential direction width W4is set to be wide enough to allow the two coil end-insulation parts46adjacent to each other in the circumferential direction to overlap each other, in the state shown inFIG. 1.

Similarly to the coil end-insulation parts46, the coil end-insulation part48of one insulator20extends axially downward from the stator core12to the outside of the slot30d,30eor30f. The coil end-insulation part48is arranged between the coil end16bof the coil16and the coil end14bof the coil14at axially downside of the stator core12, and electrically insulates the coil end16bfrom the coil end14b.

As shown inFIGS. 1 and 2, each of the insulators22is arranged in each of the slots30a,30band30c. Each insulator22has a shape the same as the coil side-insulation part44of the insulator20. Each insulator22is arranged between the coil side14aof the coil14and the inner wall surfaces28bdefining the slot30a,30bor30c, and electrically insulates the coil side14afrom the inner wall surfaces28b.

Along with this, the insulator22seals the radially inside opening of the slot30a,30bor30c. Due to this, the insulator22can prevent the coil side14afrom dropping off from the slot30a,30bor30c.

Each of the insulators24is arranged in each of the slots30d,30e, and30f. Each insulator24has a shape the same as the coil side-insulation part38of the insulator18. In particular, the insulator24has a substantially U-shaped cross-section, and includes the bottom38aand the sides38band38c.

As shown inFIG. 2, the bottom38aof one insulator24is arranged between the coil side16aof the coil16and the inner wall surface32defining the slot30d,30eor30f, and electrically insulates the coil side16afrom the inner wall surface32.

Further, the side38bof one insulator24is arranged between the coil side16aof the coil16and the side wall surface34defining the slot30d,30eor30f, and insulates the coil side16afrom the side wall surface34.

Further, the side38cof one insulator24is arranged between the coil side16aof the coil16side and the wall surface36defining the slot30d,30eor30f, and insulates the coil side16afrom the side wall surface36.

In this embodiment, since the coil side-insulation parts38of the insulators18are received in the slots30, the movement of each insulator18in the circumferential direction is restricted. In addition, the coil end-insulation parts40and42of the insulators18engage the axial end surfaces of the stator core12, due to which, the movement of each insulator18in the axial direction is also restricted.

Similarly, since the coil side-insulation parts44of the insulators20are received in the slots30, the movement of each insulator20in the circumferential direction is restricted. In addition, the coil end-insulation parts46and48of the insulators20engage the axial end surfaces of the stator core12, due to which, the movement of each insulator20in the axial direction is also restricted.

According to this embodiment, the insulators18and20are securely held in the positions shown inFIG. 1, thereby it is possible to prevent the insulators18and20from being displaced from given positions.

Further, in this embodiment, the insulators18and20have simple shapes suitable for mass production, and can be easily fitted in the slots30. Therefore, by mass-producing the insulators18and20in advance, it is possible to flexibly meet the demand of producing various kinds of motors having different numbers of slots, along with simplifying the production work. As a result, the production costs can be reduced.

Further, the insulators18and20can electrically insulate the coil sides14aand16afrom the stator core12, and also the coil ends14bfrom the coil ends16b.

Further, in this embodiment, the coil end-insulation parts40,46circumferentially adjacent to each other are arranged so as to overlap each other. According to this configuration, a gap between the adjacent coil end-insulation parts40,46can be prevented from being formed, thereby it is possible to reliably insulate the coil ends14bfrom the coil ends16b.

Next, referring toFIGS. 5 and 6, a stator10′ according to another embodiment will be described. The stator10′ according to this embodiment differs from the above-mentioned stator10in that the stator10′ further includes a plurality of connection parts50.

Each connection part50connects the coil end-insulation parts40,46of two adjacent insulators18,20. In particular, the connection parts50include connection parts50a,50b, and50c.

The connection part50aconnects the coil end-insulation parts40of two insulators18adjacent to each other. The connection part50ais arranged between the radially overlapping parts of the two adjacent coil end-insulation parts40.

The connection part50bconnects the coil end-insulation part40of the insulator18and the coil end-insulation part46of the insulator20adjacent to that insulator18. The connection part50bis arranged between the radially overlapping parts of the adjacent coil end-insulation parts40and46.

The connection part50cconnects the coil end-insulation parts46of two insulators20adjacent to each other. The connection part50cis arranged between the radially overlapping parts of the two adjacent coil end-insulation parts46.

The connection part50is e.g. adhesive agents or adhesive tapes. Alternatively, the connection part50may be constituted by an engaging part provided at one of two adjacent coil end-insulation parts40,46and a receiving part provided at the other so as to engage the engaging part, such as MAGIC TAPE (registered trademark), i.e., a hook and loop fastener.

According to this embodiment, since the coil end-insulation parts40,46can be connected to each other in the circumferential direction by connection parts50, the insulators18and20can be more-securely held in given positions. Therefore, it is possible to effectively prevent the insulators18and20from being displaced from the given positions.

In the above-described embodiment, the stator10is a cylindrical stator which constitutes a rotary motor. However, the idea of the invention is not limited to this embodiment, but can be applied to a linear stator which constitutes a linear motor.

In this case, the stator includes a back yoke linearly extending in a first direction, and a plurality of teeth extending from the back yoke in a second direction perpendicular to the first direction and arranged to align in the first direction, wherein the above-mentioned insulators18and20are respectively arranged in the slots formed between two adjacent, in a similar manner as shown inFIGS. 1 and 2.

The invention has so far been described with embodiments of the invention but the above-described embodiments are not intended to limit the scope of the invention defined by the attached claims. Further, combinations of the features described in relation to the embodiments of the invention may also be covered by the technical scope of the invention, but it does not mean that all combination of these features are necessary for solution means provide by the invention. Still further, it is obvious to those skilled in the art that various modifications or improvements can be made to the above-described embodiments.