JP2016154405A - Slot liner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a slot liner suitable for a rotary electric machine in which a coil is formed of a segment conductor.SOLUTION: The slot liner is so configured that paper-like sheets are laminated through adhesive layers on both surfaces of a base body sheet, the paper-like sheets are polyester resin nonwoven fabric, the base body sheet is a polyester resin film, and the polyester resin film is a non-stretched film.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a slot liner for a rotating electrical machine, and more particularly to a slot liner used for a rotating electrical machine in which a coil is formed by a segment conductor.

Conventionally, rotating electric machines such as motors and generators have a coil in which enameled wires (windings) in which a thin copper wire is coated with an insulating coating with a resin composition called enamel varnish or the like are wound in an oval shape. In the generator, a magnetic field generated by the coil is used as rotational power, and in the generator, a change in the magnetic field is converted into an electromotive force by the coil.
In conventional rotating electrical machines, the coil is usually used by being mounted on a member formed by laminating magnetic steel plates called a stator core or a rotor core.

The rotating electrical machine has a slot groove for attaching the coil to a core such as a stator core or a rotor core, and includes a slot liner for electrically insulating the core and the coil in the slot groove. .
The slot liner is normally a sheet body that has a rectangular shape in plan view when in a flat state, and the length of the rotating electrical machine in the direction of the rotation axis is longer than that of the core and has a surplus length in the same direction.
In the slot liner, the width direction orthogonal to the length direction is a winding direction around the coil, and the slot liner also has a surplus length in the winding direction.
That is, when the slot liner is used by being accommodated in the slot groove as described above, both end portions in the rotation axis direction protrude outward from the end surface of the core, and It is possible to wind more than one turn so that contact between the coil and the core can be more reliably prevented.

By the way, in recent years, with a drive motor and an alternator of an electric vehicle as the center, instead of using a thin round conductor winding, a coil is formed with a rectangular enameled wire enameled on a thick rectangular copper wire capable of flowing a large current. It is being considered to form.
That is, as described in Patent Document 1 below, a plurality of U-shaped segment conductors whose two leg portions are each longer than the stator core are manufactured using a flat enamel wire, and the segment conductors are produced. Are inserted from one end of the slot groove, and the tip of the leg is protruded from the other end of the slot groove. Then, the tip of the leg of one segment conductor is separated from the other. In recent years, it has been studied to form a stator coil by brazing the end portions of the leg portions of the segments and conducting them.

JP 2005-124388 A

Conventionally, the slot liner has a cylindrical shape corresponding to the shape of the slot groove when being accommodated in the slot groove, and is used in a form inserted through the opening of the slot groove on the end face of the core.
If the conventional slot liner generates a strong frictional force between the inner wall of the slot groove of the core, a strong force is required to enter the slot groove, yielding to such a force. May buckle.
Therefore, conventionally, a laminated sheet in which a sheet-like sheet such as aramid paper is laminated on both sides of a base sheet having excellent stiffness such as a biaxially stretched polyester resin film has been used to form a slot liner. It has been.

In recent years, coils have been formed using segment conductors as described above, and a method for accommodating the slot liner in the slot groove has been adopted. Yes.
That is, the leg portions of the plurality of segment conductors accommodated in the same slot groove are aligned in advance, and the leg portions are arranged in the same manner as when accommodated in the slot groove. In recent years, a method in which a slot liner is wound around a leg portion and the slot liner wound around the leg portion is accommodated in a slot groove simultaneously with a segment conductor has been adopted.

Although the aramid paper is more expensive than a general resin sheet, it is used as a component of a slot liner because it has excellent stiffness and slipperiness. It is also possible to reduce the cost by using a paper sheet other than aramid paper.
And when the present inventors diligently studied paying attention to this point, heat shrinkage by a biaxially stretched polyester resin film conventionally used for a base sheet when another paper-like sheet is adopted instead of aramid paper Has been found to affect the entire slot liner and reduce the heat resistance of the slot liner.
In addition, since such a point has not been paid attention until now, the solution etc. are not examined, and the slot liner suitable for the rotary electric machine by which the coil formation was carried out by the segment conductor was not provided until now.

  In view of the above situation, an object of the present invention is to provide a slot liner suitable for a rotating electrical machine in which a coil is formed by a segment conductor.

  The present invention relating to a slot liner for solving the above problems is used in a rotating electrical machine in which a coil is formed by a segment conductor, and is interposed between the coil and the core in a slot groove of the core of the rotating electrical machine. A slot liner used by being mounted, having a laminated structure, wherein a paper-like sheet is laminated on both surfaces of a base sheet via an adhesive layer, and the paper-like sheet is a polyester resin nonwoven fabric, The base sheet is a polyester resin film, and the polyester resin film is an unstretched film.

According to the present invention, since the base sheet is an unstretched polyester resin film, thermal contraction of the slot liner is suppressed even if a polyester resin nonwoven fabric is used as the paper sheet.
That is, according to the present invention, a slot liner suitable for a rotating electrical machine in which a coil is formed by a segment conductor can be provided.

The schematic perspective view of an alternator. The schematic plan view of a stator core. The A section enlarged view of FIG. 1 is a schematic cross-sectional view showing a cross-sectional structure of a slot liner according to an embodiment. FIG. 3 is a schematic three-side view showing a test method for a heat shrinkage evaluation test.

Embodiments of the present invention will be described with reference to the drawings.
Here, the slot liner according to the present embodiment will be described by taking as an example a case where the rotating electrical machine is an alternator such as a hybrid vehicle (HEV) or an electric vehicle (EV).
More specifically, here, the alternator includes a rotor including a permanent magnet and a stator including a coil, and includes the coil formed by a segment conductor, and a slot liner includes the slot liner. The present invention will be described by taking as an example a case where it is used for an alternator stator.
FIG. 1 is a perspective view of a stator 1 of an alternator (hereinafter also referred to as “SC alternator”) according to the present embodiment. As shown in the figure, the stator has a stator core 10 and a coil 20. ing.

  FIG. 2 is a plan view of the stator 1 as seen from a direction orthogonal to the rotation axis direction (arrow AD) of the rotor (not shown). FIG. 3 shows a coil formed on a portion A of the stator core 10 shown in FIG. It is sectional drawing which showed a mode that 20 was accommodated.

As shown in these drawings, the stator 1 has a short cylindrical stator core 10 and a coil 20 attached to the stator core 10.
A plurality of slot grooves 11 are formed on the inner peripheral surface side of the cylindrical stator core 10.
The plurality of slot grooves 11 are arranged in the stator core 10 in a state where the individual slot grooves extend along the rotation axis direction AD and are spaced apart from each other in the circumferential direction (arrow RD) of the stator core 10. Has been.
The slot groove 11 is formed over the entire length of the stator core 10 in the rotation axis direction AD, and includes one end face 10a (upper side in FIG. 1, hereinafter also referred to as “upper end face 10a”) and the other end face 10b (hereinafter referred to as “upper axis direction”). An opening 11b having the same shape as the cross-sectional shape of the slot groove 11 is formed in the “lower end surface 10b”.

Since the stator core 10 has the plurality of slot grooves 11 in parallel as described above, a plate-like protrusion is formed between the slots.
A plurality of the plate-like protrusions 12 (hereinafter also referred to as “teeth 12”) are formed in a state of protruding toward the inner side in the radial direction (arrow DD) of the stator core 10.
In addition, the said teeth 12 have the wide part 12a which spreads in the circumferential direction RD of the stator core 10 in the protrusion direction front-end | tip part, and cross-sectional shape is a T-shape.
Therefore, on the inner peripheral surface side of the stator core 10, the width of the slot groove 11 is narrowed to form a slightly linear opening 11 a.

The coil 20 is composed of a plurality of segment conductors 21 connected to each other.
The segment conductor 21 ′ before the coil formation is a flat enameled wire bent into a U shape, and includes two leg portions 21b and a head portion 21a ′ connecting the leg portions 21b ′. It is a thing.
The segment conductor 21 ′ in the present embodiment has a copper wire exposed portion from which the insulating coating is peeled off at the tip portion 21bx ′ of the leg portion 21b ′ opposite to the head side.
In the coil 20 in this embodiment, the leg portion 21 b ′ of the segment conductor 21 ′ is inserted from the opening 11 b of the slot groove in the upper end surface 10 a of the stator core 10, and the tip portion 21 bx ′ is connected to the lower end surface of the stator core 10. After protruding from 10b, the leg portion 21b 'of one segment conductor 21' and the leg portion 21b 'of another segment conductor 21' are electrically connected at the conductor exposed portion, and an insulation treatment is further applied to this connection portion. It was made by applying.
Therefore, the stator 1 in the present embodiment has a coil end portion formed by the head portion 21a ′ of the segment conductor 21 ′ on the upper end surface side of the stator core 10, and the leg portions are connected to the lower end surface side. It has a coil end part constituted by the connection part 21x.

Four leg portions 21b of the segment conductors 21 forming the coils 20 are accommodated in the slot grooves 11 of the stator core 10, respectively, and each slot groove 11 is arranged in a row outward from the inside. In total, four legs 21b are accommodated.
A slot liner 40 is interposed between the four leg portions 21b and the inner wall surface of the slot groove 11, and the slot liner 40 is configured to bundle the four leg portions 21b together. It is arranged in the slot groove.
More specifically, the slot liner 40 is vertically attached along the longitudinal direction of the leg portion 21b of the segment conductor 21, and is disposed in the slot groove so as to circulate around the four leg portions 21b more than once. Both end portions in the rotational axis direction AX are arranged in the slot groove so as to protrude outward in the rotational axis direction from the upper end surface 10a and the lower end surface 10b of the stator core 10.

Since the slot liner 40 is arranged in the slot groove so as to circulate around the four leg portions 21b at least once as described above, the slot liner 40 has a shape in which both end portions in the circumferential direction are overlapped. It is arranged in the groove.
That is, in the stator 1 of the present embodiment, the overlapping portion 40a where the slot liners 40 overlap each other is formed in the slot groove.
And the stator 1 of this embodiment has located the overlapping part 40a where this slot liner 40 overlapped on the radial direction outer side.

The slot liner 40 in this embodiment is a sheet body having a laminated structure as shown in FIG. 4, and a sheet-like sheet 43 is laminated on both surfaces of a base material sheet 41 with an adhesive layer 42 interposed therebetween.
In the slot liner 40, the paper sheet 43 is a polyester resin nonwoven fabric, the base sheet 41 is a polyester resin film, and the polyester resin film is an unstretched film.

The polyester-based resin film used as the base sheet 41 in the present embodiment is not particularly limited as long as it is an unstretched polyester-based resin film. Polyethylene terephthalate resin (PET), polytrimethylene terephthalate resin (PTT), polybutylene A film made of terephthalate resin (PBT), polyethylene naphthalate resin (PEN), polybutylene naphthalate resin (PBN), or the like can be employed.
In the present embodiment, among the materials exemplified above, a PET film, a PBT film, a PEN film, or the like is preferably used as the base sheet 41.
In particular, since various types of PET films having different thicknesses and resin properties are commercially available, selecting those suitable for the slot liner from these commercially available products can cause the slot liner to exhibit the desired properties. It is preferable in that it is easy.
As the unstretched PET film, not only a single-layer structure but also a three-layer structure in which a recycled material layer is sandwiched between two virgin material layers can be used as the base sheet 41. .

The polyester resin film used as the base sheet 41 is preferably a polybutylene terephthalate resin (PBT) film or a polyethylene terephthalate resin (PET) film.
Moreover, it is preferable that these are low oligomer goods whose oligomer extraction amount is 0.5 mass% or less.
The oligomer extraction amount is obtained, for example, by boiling a 38 mm × 38 mm film in 20 cc of xylene at 139 ° C. for 2 hours, slowly cooling it, taking out the film, and measuring the amount of oligomer in the xylene. It is done.
The amount of oligomer in xylene is determined from the absorbance at a measurement wavelength of 240 nm, and is determined from a calibration curve prepared in advance for the relationship between the concentration of the oligomer and the absorbance.
In addition, the measurement of a light absorbency can use UV-VIS-NIR spectrophotometer UV-3101PC made from SHIMADZU, for example.

From the viewpoint of imparting insulation reliability to the slot liner 40, the base sheet 41 has a volume resistivity of 1 × 10 ¹² Ω · cm or more at normal temperature (eg, 23 ° C.) (usually 1 × 10 ¹⁶ Ω · cm or less), and preferably has a volume resistivity of 1 × 10 ¹³ Ω · cm or more.
As the base material sheet 41, a polyester-based resin film having a thickness of 5 to 300 μm can be usually adopted, and the base material sheet 41 preferably has a thickness of 25 μm or more and 125 μm or less.

The adhesive layer 42 for adhering the base sheet 41 and the paper sheet 43 is not particularly limited, and may be constituted by a general pressure-sensitive adhesive or a reaction curable adhesive.
Examples of the pressure-sensitive adhesive include rubber-based, acrylic-based, silicone-based, and urethane-based adhesives. Examples of the reaction-curable adhesive include acrylic-based, urethane-based, silicone-based, and epoxy-based adhesives. Things.
The adhesive layer 42 can usually have a thickness of 1 to 50 μm, preferably 5 to 10 μm.
The adhesive layer 42 may have different thicknesses on one surface side of the base sheet 41 and the other surface side opposite to the one surface side, or may have a common thickness.
Further, the adhesive layer 42 may be common even if the adhesive used on one side and the other side of the base sheet 41 is different.

The paper-like sheet 43 can be a fiber nonwoven fabric made of the polyester resin exemplified for the base sheet 41.
As the polyester resin nonwoven fabric, a polyester resin fiber is formed into a sheet using a binder, or a polyester resin fiber is formed into a sheet by heat-sealing without using a binder. In general, one having a thickness of 5 to 300 μm can be adopted.
Further, as the polyester resin non-woven fabric, simply by mass per area (basis weight) is, for ^example, may be formed of the ^{24g / m 2 ~40g / m 2} .
The polyester resin nonwoven fabric preferably has a low friction coefficient and preferably has a static friction coefficient of 0.2 or less so that the slot liner exhibits excellent slipperiness when inserted into the slot groove.
Similarly to the adhesive layer 42, the paper-like sheet 43 need not have the polyester resin nonwoven fabric constituting one surface of the slot liner 40 and the polyester resin nonwoven fabric constituting the other surface in common. Different thicknesses and materials may be used.
In addition, it is preferable that the structural member is selected so that the slot liner 40 may have a tensile strength of 25 MPa or more.

The slot liner 40 can more reliably prevent contact between the coil 20 and the stator core 10 as the height protruding from the end faces 10a and 10b of the stator core 10 is higher.
Therefore, the slot liner 40 used for the stator 1 of the present embodiment is preferably selected to have a size such that the height protruding from both end faces 10a and 10b is 1 mm or more, and the protruding height is 2 mm or more, respectively. It is particularly preferable to select a size such that
However, since it is difficult to expect an effect corresponding to an excessively high protrusion height, the slot liner 40 preferably has a height protruding from both end faces 10a and 10b of 10 mm or less, respectively. It is particularly preferable that each of the lengths is 5 mm or less.

The slot liner 40 in the present embodiment has a size capable of forming the overlapping portion 40a as described above.
In other words, the slot liner in which the overlapping portion 40a is not formed is, in other words, lacking dimensions in the direction in which the four leg portions accommodated in one slot groove go around, and there is no gap in the slot groove. Will be generated.
If such a gap is formed, reliability in electrical insulation may be reduced. Therefore, in the slot liner 40, the overlapping width of the overlapping portion 40a (the forming width in the direction of circling the leg portion) is 1 mm or more. It is preferably 2 mm or more.
However, if the overlapping width of the overlapping portion 40a is excessive, the occupancy rate of the segment conductor 21 in the slot groove is also reduced. Therefore, the overlapping width is preferably 5 mm or less.

The slot liner 40 of this embodiment can be accommodated in the slot groove 11 together with the segment conductor 21 ′ before coil formation.
That is, the slot liner 40 of the present embodiment can bundle the leg portions 21 b ′ of the four segment conductors 21 ′ accommodated in one slot groove 11 and accommodate the leg portions 21 b ′ together with the bundled leg portions in the slot groove 11.
Therefore, the slot liner 40 of the present embodiment is not housed in the slot groove alone unlike the conventional slot liner, so that troubles such as buckling are unlikely to occur.
As described above, in the conventional slot liner, aramid paper excellent in slipperiness is used as a paper sheet, and a biaxially stretched polyester resin film excellent in stiffness is used as a base sheet.
On the other hand, the slot liner 40 of the present embodiment employs a polyester resin nonwoven fabric as a paper sheet, and uses a non-stretched polyester resin film as a base sheet, so that it is softer than conventional slot liners. It has become a thing.
That is, the slot liner 40 of the present embodiment has a better winding property on the leg portion 21b 'than the conventional one, and the space required in the slot groove is reduced compared to the conventional one. Can be.

In addition, when a stretched resin film is used as a base sheet, when the base sheet is heated to a temperature equal to or higher than the glass transition point of the resin constituting the resin film, There is a risk of contraction in the opposite direction causing thermal contraction of the slot liner.
On the other hand, since the non-stretched polyester resin film is adopted as the base sheet 41, the slot liner 40 in the present embodiment is less likely to be thermally contracted.
That is, the slot liner 40 in this embodiment is less likely to cause unintended exposure of the segment conductor 21 due to thermal contraction even if the overlapping width of the overlapping portion 40a is not ensured more than necessary.
For these reasons, the slot liner 40 in the present embodiment is also effective in improving the occupation ratio of the coil 20 in the slot groove.

In the present embodiment, an example of a five-layer structure is given so that the slot liner has a minimum necessary configuration, but the slot liner of the present invention is not limited to a five-layer structure.
In this embodiment, the slot liner is used in the stator of the SC alternator. However, the slot liner of the present invention can be applied to a motor and other rotating electric machines.
Furthermore, the slot liner of the present invention is not limited to the above-described examples, and various modifications can be added as appropriate.

EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these.
Example 1
A wet non-woven fabric (100% polyester resin, high-density type, trade name "05TH20S" manufactured by Hirose Paper Industries Co., Ltd.) on both sides of an unstretched PBT film (thickness 25 μm) manufactured by OG Film , 30 μm thick) to form a slot liner having a thickness of about 100 μm.

(Example 2)
Except for changing polyester resin non-woven fabric to polyester resin non-woven fabric manufactured by Asahi Kasei Co., Ltd. (non-woven fabric having three layers of spunbond nonwoven fabric / melt blown nonwoven fabric / spunbond nonwoven fabric, trade name “PRECISE: thickness 32 μm)” A slot liner was prepared as in Example 1.

(Reference Example 1)
A 37 μm thick aramid paper (manufactured by DuPont, trade name “NomexPaper”) was laminated on both sides of a biaxially stretched PET film (thickness 25 μm) to produce a slot liner having a thickness of about 120 μm.

(Evaluation)
About the obtained slot liner, heat shrinkability evaluation was implemented by the method as shown in FIG.
That is, a test piece TP having a length of 140 mm and a width of 40 mm was cut out from the slot liner and sandwiched between two iron plates SP having a length of 120 mm and a width of 20 mm.
At this time, the two iron plates SP were arranged so as to overlap each other with their edges aligned, and the test piece TP was arranged to extend 10 mm outward from the periphery of the iron plate SP.
Then, at both ends in the longitudinal direction of the iron plate SP, the test piece TP was gripped with a clamping force of 1 kgf, respectively, to prepare a test body, and this test body was housed in an oven set at a temperature of 230 ° C.
The number of test specimens produced (N number) was 3 for each of Examples 1 and 2 and Reference Example 1, and after a predetermined time had elapsed (168 hours, 408 hours, 600 hours, 792 After 984 hours), the sample was taken out and subjected to a pressure resistance test (cut-off current 10 mA).
The pressure resistance test was performed in air, and an AC voltage of up to 10 kV was applied between the steel plates at a boosting speed of 1000 V / s.
A similar test was conducted at 250 ° C.

As a result, in the slot liners of Example 1 and Example 2, the reference example using aramid paper showed almost no heat shrink phenomenon in the entire test period of 984 hours even at the test temperature of 250 ° C. In this situation, heat shrinkage was observed.
However, the slot liners of Example 1 and Example 2 passed all tests including the test after 984 hours at the test temperature of 230 ° C. and the test temperature of 250 ° C. in the same manner as the slot liner of the reference example. did.
That is, it was confirmed that the slot liners of Example 1 and Example 2 exhibited excellent heat resistance.

In addition, the biaxially stretched PET film used as the base sheet in the reference example and the unstretched PBT film used as the base sheet in the slot liner of the example were accommodated for 24 hours while being opened at 250 ° C. so as to have heat shrinkability. As a result of comparison, the unstretched PBT film showed almost no heat shrinkage due to a measurement error in the dimensional change after heating with respect to the initial stage.
On the other hand, it was confirmed that the biaxially stretched PET film causes thermal shrinkage of 10% or more.
From this, only by changing the paper sheet constituting the slot liner of the reference example from aramid paper to a polyester nonwoven fabric, in the pressure resistance test as described above, the thermal shrinkage was larger than that of the slot liner of Examples 1 and 2. It is thought that it will be rejected at an early stage.
Further, the slot liner of the example is considered to be excellent in flexibility as compared with the slot liner of the reference example using aramid paper, and can be easily deformed according to the shape in the slot groove.
Further, in the slot liner of the embodiment, it is considered that it is easier to bundle the segment conductors around the plurality of segment conductors accommodated in one slot groove compared to the slot liner of the reference example.

  This also shows that the slot liner of the present invention is excellent in heat resistance and suitable for a rotating electrical machine in which a coil is formed by a segment conductor.

1: Stator, 10: Stator core, 11: Slot groove, 20: Coil, 40: Slot liner

Claims (2)

A slot liner used for a rotating electrical machine in which a coil is formed by a segment conductor, and used between the coil and the core in a slot groove of the core of the rotating electrical machine,
Having a laminated structure,
Paper sheets are laminated on both sides of the base sheet via an adhesive layer,
A slot liner wherein the paper sheet is a polyester resin nonwoven fabric, the base sheet is a polyester resin film, and the polyester resin film is an unstretched film.   The slot liner according to claim 1, wherein the paper sheet is a polyethylene terephthalate resin nonwoven fabric and the base sheet is an unstretched polyethylene terephthalate resin film.