JP6300035B2 - Electric motor cooling structure - Google Patents

Description

  The present invention relates to an electric motor cooling structure, and more particularly to an electric motor cooling structure using a graphene sheet.

Conventionally, electric motors (electric motors) have been used as power sources in various fields.
When the electric motor rotates by converting electric energy into kinetic energy, a part of the electric energy is converted into heat energy to generate heat.
In order to insulate the inner wall portion of the housing from the coil end of the stator from the viewpoint of safety, a space portion is provided between them for a predetermined distance.
Accordingly, it is difficult to increase the thermal conductivity from the coil end to the housing, and it is necessary to take measures against heat in the electric motor.
In particular, a large (high output) electric motor mounted on an electric vehicle has a larger heat generation amount, and this heat generation amount causes a reduction in the efficiency of the electric motor. Therefore, various cooling techniques have been proposed.

The cooling structure of the electric motor of Patent Document 1 includes a rotor, a stator around which a stator coil is wound, a housing that houses the rotor and the stator, and a lubrication formed between the housing and a coil end on one end side. A first storage tank for oil, a second storage tank for lubricating oil formed between the housing and the coil end on the other end side, and a communication path communicating the first storage tank and the second storage tank. And the upper part of the communication path is formed to be above the oil level of the lubricating oil stored in the first and second storage tanks.
As a result, the coil end is submerged while cooling of the lubricating oil in the communication passage is suppressed, thereby achieving cooling.

In recent years, graphene (also referred to as graphene sheet) has attracted attention as a material having excellent mobility performance. Graphene is a planar substance having a thickness of only one atomic layer in which carbon atoms are bonded so as to draw a hexagonal network.
The mobility of charged particles (electrons) in graphene is 15000 cm ² / Vs at room temperature, while the development of properties related to mobility (electricity, heat, strength, etc.) is limited to the planar direction. Graphene is usually used in the form of a laminate (graphite) in which a plurality of graphenes are laminated.

JP 2014-225971 A

The cooling structure of the electric motor of Patent Document 1 uses the insulating space for the lubricating oil reservoir, and suppresses the retention of the lubricating oil in the communication path without forming a vent in the housing. .
However, since the cooling structure of the electric motor of Patent Document 1 is a heat exchange type wet cooling with a so-called lubricating oil in which the coil end is submerged and cooled, the lubricating oil and the oil for circulating the lubricating oil are used. Roads and further maintenance of the lubricating oil is required, which may increase the production cost.
In the case of a large electric motor, the rate of temperature rise is extremely fast (for example, about 200 ° C. increase in 3 seconds), and there is a possibility that the heat exchange type wet cooling using lubricating oil may not be able to catch up with the cooling capacity of each member in the electric motor. is there.
Although the technology of Patent Document 1 forms a cooling water channel separately in the wall of the housing in addition to a cooling mechanism using lubricating oil, and further improves the cooling capacity in the electric motor, Issues still remain from a cost perspective.

As described above, since it is known that graphene is excellent in thermal conductivity under a specific use condition, it can be considered to utilize graphene for a cooling mechanism.
When graphene is used for a cooling mechanism, it is necessary to set an application site, an application form, and the like in consideration of the peculiarity that a physical property value is greatly different between a surface direction and a thickness direction.
Therefore, as a result of the study by the present inventor, even if the graphene is simply brought into surface contact with the coil end that is the part to be cooled, the amount of heat that can secure the cooling ability is ensured if the surface contact is not made uniformly over a predetermined pressing force. It was found that no conduction from graphene to graphene from the end.
In addition, since the structure of the insulating space where the coil end is arranged is narrow and complicated, it is not easy to bring the graphene into surface contact with the coil end with a uniform pressing force.

  An object of the present invention is to provide a cooling structure or the like of an electric motor that can improve the cooling capacity by bringing a laminate of graphene sheets into surface contact with a coil end with a uniform pressing force.

  The invention of claim 1 includes a rotor, a stator around which a stator coil is wound, a housing that accommodates the rotor and the stator, and an insulating space formed between the housing and the coil end of the stator. In the cooling structure of the electric motor provided, a plurality of laminates arranged in the space for insulation and laminated with a plurality of graphene sheets, and the plurality of laminates in the thickness direction with respect to the coil end and the housing And a pressurized air containing bag containing pressurized air to be pressed from above.

  In this electric motor cooling structure, since it has a plurality of laminated bodies arranged in the insulating space and laminated with a plurality of graphene sheets, a heat exchange cooling medium such as lubricating oil can be omitted. From the viewpoint of safety, it is possible to dispose a plurality of laminates using the insulating space while maintaining the air insulating space that is indispensable. Since it includes a compressed air storage bag that stores compressed air that presses a plurality of laminates from the thickness direction against the coil end and the housing, the coil end and the housing are not affected by the shape of the insulating space. The graphene sheet can be brought into surface contact with the coil end with a uniform pressing force while securing an air insulating layer.

The invention of claim 2 is characterized in that, in the invention of claim 1, an internal pressure of the pressurized air accommodation bag is set to 100 to 700 kPa.
According to this configuration, the superior heat conduction characteristics of the graphene sheet can be reliably exhibited.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the housing includes a housing end member that closes an axial end portion of the rotor, and the pressurized air storage bag penetrates the housing end member. And a pressurized air introduction path extending to the outside, and a pressure regulating valve disposed at the tip of the pressurized air introduction path.
According to this configuration, since the pressurized air storage bag can be assembled in an unfilled state, the assembly workability can be improved, and the compressed air storage bag is filled after assembly. The pressure management can be facilitated.

According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the laminated body includes an intermediate laminated body formed by laminating the plurality of graphene sheets, and the rotor on two parallel sides. It is characterized in that it is constituted by a plurality of diffractions by a fold line including a fold line parallel to the axis.
According to this configuration, the heat conduction amount of the heat conduction path from the coil end to the housing can be increased regardless of the area occupied by the laminated body with respect to the coil end and the housing.

  According to the cooling structure of the electric motor of the present invention, the cooling capacity is obtained by bringing the laminate of graphene sheets into surface contact with the coil end with uniform pressing force while securing an air insulating layer between the coil end and the housing. Can be improved.

1 is a longitudinal sectional view of an electric motor according to Embodiment 1. FIG. It is a principal part enlarged view of the storage bag periphery part of FIG. It is a principal part enlarged view of the step part periphery part of FIG. It is a disassembled perspective view except the rotor of an electric motor. It is explanatory drawing of a graphene sheet. It is explanatory drawing of an intermediate | middle laminated body. It is a perspective view of a laminated body. It is a graph which shows the relationship between the pressing force of a graphene sheet, and thermal conductivity. It is explanatory drawing of a folding process. It is a top view of the penetration part periphery part of a laminated body. It is a longitudinal cross-sectional view of a heat conduction bolt. It is a principal part enlarged view of the contact part of the heat conductive volt | bolt of FIG. 3, and a laminated body. It is the XIII-XIII sectional view taken on the line of FIG. It is a perspective view which shows the modification of an extension part.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
The following description exemplifies the application of the present invention to a permanent magnet synchronous motor whose drive is controlled by a predetermined control unit, and does not limit the present invention, its application, or its use. . In the following description, the left side in the figure is the left side, and the upper side in the figure is the upper side. Moreover, in FIG.3, FIG.7, FIG.10, FIG. 13, the heat transfer direction is shown using the arrow.

Embodiment 1 of the present invention will be described below with reference to FIGS.
As shown in FIG. 1, an electric motor 1 as an electric motor includes a cylindrical rotor 10, a cylindrical stator 20 disposed on the outer peripheral side of the rotor 10, and a cylindrical shape that houses the rotor 10 and the stator 20. Housing 30 and the like.
The electric motor 1 is configured such that the rotor 10 housed inside the stator 20 is rotated by a magnetic field generated when a controlled alternating current flows through the stator 20.

First, the rotor 10 will be described.
As shown in FIG. 1, the rotor 10 includes a rotor shaft 11 that also serves as an output shaft of the electric motor 1, a rotor core 12, and a pair of left and right end plates 13.
The rotor shaft 11 has a right end connected to the load device 2 and a left end and a middle portion on the right end side supported rotatably on the housing 30 via bearings 35 and 36.

A large number of iron cores made of electromagnetic steel plates are laminated in the left-right direction, and the rotor core 12 is integrally formed by thermocompression bonding or the like. The rotor core 12 is fitted to the rotor shaft 11 to prevent rotation, and a predetermined number of permanent magnets (not shown) are embedded in the outer diameter side in the circumferential direction.
The pair of left and right end plates 13 are provided in contact with both left and right end portions of the rotor core 12 to position the rotor core 12 in the left-right direction with respect to the rotor shaft 11.

Next, the stator 20 will be described.
As shown in FIGS. 1, 2, and 4, the stator 20 includes a cylindrical stator core 21, a stator coil 22, and the like.
The stator core 21 has a large number of iron cores made of electromagnetic steel plates laminated in the left-right direction, and is integrally formed by thermocompression bonding or the like. The outer periphery of the stator core 21 is fixed to the inner wall 31c of the housing 30 and the inner diameter portion of the stator core 21 is disposed opposite to the outer diameter portion of the rotor core 12 with a small gap. The stator core 21 is provided with a plurality of ribs (not shown) at regular intervals in the circumferential direction, and a copper enameled wire stator composed of a U-phase coil group, a V-phase coil group, and a W-phase coil group on these ribs. The coil 22 is wound according to a standard method.

The stator coil 22 includes a pair of left and right coil ends 23 that are folded back from the left and right ends of the stator core 21 so as to protrude outward in the left and right (axial center) direction.
As shown in FIGS. 1 and 2, the pair of left and right coil ends 23 are formed between a large diameter portion 23 a formed at a position separated from the stator core 21, and between the large diameter portion 23 a and the stator core 21. And a small-diameter portion 23b having a narrower vertical width than the large-diameter portion 23a in a longitudinal sectional view. On both the left and right sides of the stator core 21, there are recessed portions 24 that are recessed toward the inner diameter (axial center) of the rotor shaft 11 in a longitudinal sectional view by the vertical wall portion, the small diameter portion 23b, and the large diameter portion 23a of the stator core 21. Each is formed.

An insulating heat dissipating paste is applied to the surfaces of the insulating coatings of the pair of left and right coil ends 23 (large diameter portion 23a and small diameter portion 23b).
As the insulating heat dissipation paste, a material that ensures thermal conductivity and heat dissipation while ensuring insulation, for example, a paste generated by a hydrolysis reaction and silanol dehydration condensation reaction of an alkoxide compound is used. This insulating heat radiation paste is also applied to the vertical wall portion of the stator core 21.

The winding method of the stator coil 22 can be roughly divided into a concentrated winding method and a distributed winding method.
In the concentrated winding method, the magnetic poles do not overlap and the interference between the stator coils 22 is small, so that the left and right lengths of the coil ends 23 can be shortened, but the amount of magnets used per output torque is large and cogging increases.
In the distributed winding method, since the magnetic poles of each phase partially overlap and the stator coil 22 intersects at the coil end 23, the left and right lengths of the coil end 23 become longer and the shape becomes complicated, but the output torque The amount of magnet used per hit is small and cogging is reduced.
In the present embodiment, in order to ensure a large exposed area of the coil end 23 exposed from the stator core 21, a distributed winding method in which the left and right lengths of the coil end 23 are increased is adopted.

Next, the housing 30 will be described.
As shown in FIGS. 1 to 4, the housing 30 is made of an aluminum alloy material, and has a bottomed cylindrical main body portion 31 and a substantially disc-shaped end portion 32 that closes the right opening of the main body portion 31. (Housing end member) and the like. Therefore, the amount of heat input to the main body portion 31 and the end portion 32 is quickly transmitted through the inside and radiated to the outside.
The main body 31 is formed with a bearing 35, three bolt holes 34h, a step portion 31a, a plurality of recessed portions 31d provided in the step portion 31a, and a plurality of bolt holes 44h.
The bearing 35 is configured by a bearing installed in the central portion of the left vertical wall. The three bolt holes 34h are formed in the end wall portion 31b at the right end portion at equal intervals in the circumferential direction.
As shown in FIG. 3, the plurality of cylindrical recessed portions 31d are formed so as to be recessed leftward from the bottom of the stepped portion 31a. The plurality of bolt holes 44h are formed to have a smaller diameter than the recessed portions 31d, and are respectively formed so as to be recessed leftward from the bottoms of the plurality of recessed portions 31d.

In the end portion 32, a bearing 36, three openings 32a, and a valve opening 32b are formed. The bearing 36 is configured by a bearing installed at the central portion of the vertical wall.
The three openings 32a are respectively formed in three bolt boss portions projecting in the outer diameter direction at positions at equal intervals in the circumferential direction. The valve opening 32 b is formed so as to penetrate the vertical wall left and right in the middle in the radial direction of the vertical wall of the end portion 32.
The end portion 32 is fixed to the main body portion 31 by fastening the bolts 34 inserted through the openings 32a into the bolt holes 34h, respectively.

  As shown in FIGS. 1 and 2, the coil end 23 is separated from the main body portion 31, the end portion 32, and a presser plate 40 described later by a predetermined distance in order to insulate the coil end 23 from the housing 30. Therefore, the end portion 23c of the large diameter portion 23a, the outer diameter portion 23d of the large diameter portion 23a, the outer diameter portion 23e of the small diameter portion 23b, the inner wall portion 31c of the main body portion 31 (housing 30), the end portion 32, etc. 33 (insulating space) is formed.

In the space 33 on the right side, a pressing plate 40 made of an aluminum alloy, a plurality of laminated bodies 50 disposed on the left side of the pressing plate 40, and the plurality of laminated bodies 50 with a predetermined pressure. A storage bag 60 (pressurized air storage bag) for pressing is disposed.
In the present embodiment, since the plurality of laminated bodies 50 and the storage bags 60 that press these are disposed in the right space portion 33, the configuration of the right side portion will be mainly described below.
In addition, you may arrange | position the several laminated body 50, the accommodation bag 60, etc. in the space part 33 of both right and left sides, respectively.

As shown in FIGS. 1 to 4, the presser plate 40 is integrally configured by an annular ring portion 41 and a cylindrical portion 42.
The annular portion 41 is disposed so as to be orthogonal to the axis of the rotor shaft 11, and the outer diameter portion is fixed to the bottom portion of the step portion 31 a via a plurality of heat conduction bolts 44.
The annular portion 41 is formed with a plurality of openings 41a through which the heat conduction bolts 44 can be inserted, and a valve opening 41b disposed to face the valve opening 32b.
As shown in FIG. 4, the plurality of openings 41 a are formed by a plurality of sets of three openings 41 a arranged at the apex of the regular triangle in the circumferential direction.
The inner peripheral edge portion of the annular portion 41 is configured to be at substantially the same height as the inner diameter portion of the stator core 21 when the presser plate 40 is fixed to the bottom portion of the step portion 31a.
The cylindrical portion 42 extends to the left in parallel to the axis of the rotor shaft 11 from a position facing the inner diameter portion of the large diameter portion 23 a from the inner diameter edge portion of the annular portion 41.
The left end portion of the cylindrical portion 42 is separated from the inner diameter portion of the large diameter portion 23a by a predetermined distance in the vertical direction.

Next, the some laminated body 50 is demonstrated.
The plurality of stacked bodies 50 constitute a dry cooling mechanism that cools the coil end 23 by transmitting the heat input from the coil end 23 to the inner wall portion 31 c of the housing 30. The plurality of laminated bodies 50 are disposed in the space portion 33 at predetermined intervals in the circumferential direction.
In addition, since all the laminated bodies 50 are the same structures, the one laminated body 50 is demonstrated as an example.

As shown in FIGS. 5 to 7, the laminated body 50 is configured by an intermediate laminated body 52 (graphite) in which a plurality of graphene sheets 51 in which only one layer of a network crystal of carbon atoms exists in a planar shape is stacked uniformly. Has been. The intermediate laminate 52 that is a layered crystal has a thickness of, for example, about 75 μm. The mobility of charged particles (electrons) of the intermediate laminate 52 (graphene sheet 51) is 15000 cm ² / Vs at room temperature in the layer direction (plane direction), and excellent heat conduction performance (1000 to 1500 W / m · K). ).
As shown in FIG. 8, in the intermediate laminate 52, the thermal conductivity increases as the pressing force from the direction perpendicular to the surface with respect to the heat source increases, and the thermal conductivity converges when the pressing force becomes sufficiently large. It has the characteristic to do.

As shown in FIG. 7, a long laminate having a thickness of about 2 mm is obtained by folding the intermediate laminate 52 on which the graphene sheets 51 are laminated by an even number of times, for example, 28 diffractions, with two parallel folding lines 52a. 50 is formed. Here, the meaning of stacking includes stacking a plurality of graphene sheets 51 and stacking a plurality of intermediate stacks 52 by diffracting a plurality of layers.
Of the laminate 50, the amount of heat input to the lowermost intermediate laminate 52 is transmitted to the uppermost intermediate laminate 52 with a high thermal conductivity via a plurality of folding lines 52a.

Further, the amount of heat input to the left end portion of the lowermost intermediate laminate 52 is transmitted to the right end portion using all the folded intermediate laminates 52 as heat conduction paths as shown by arrows in FIG. Is done.
Here, when a lattice defect occurs in the hexagonal lattice structure of the graphene sheet 51, the heat conduction path is reduced due to the structure of the graphene sheet 51, so that the thermal conductivity is lowered and the heat conduction performance may be impaired. is there.
That is, when the folding line 52a of the laminated body 50 is completely bent, a lattice defect is generated in the graphene sheet 51. Therefore, a predetermined curvature is formed so that the folding line 52a is not completely bent. Therefore, as shown in FIG. 9, in the folding process of the laminated body 50, the rod-shaped jigs 70 having a circular cross section are brought into contact with the respective folding lines 52 a, respectively, and then the bar-shaped jig 70 is folded on the corresponding one side. The intermediate laminated body 52 is folded without completely bending the intermediate laminated body 52 (graphene sheet 51) by concentrating them at one place so that they overlap each other and concentrating them at one place so that the other folding lines 52a overlap. It is.

As shown in FIG. 7, the laminated body 50 is formed with four connecting portions 53 arranged at equal intervals in the longitudinal direction and three insertion portions 54 to 56 in the right half portion.
The four connecting portions 53 are extended in one direction from one long side of the lowermost intermediate laminate 52, and extended from one long side of the uppermost intermediate laminate 52 to one side. Each of the extended portions 52c is connected by an adhesive or the like. And the laminated body 50 which can maintain the folded long shape is formed by connecting all the folding lines 52a of the other side of the laminated body 50 with an adhesive material etc.

As shown in FIGS. 7 and 10, the three insertion portions 54 to 56 are formed at positions corresponding to the vertices of a substantially equilateral triangle, respectively. The insertion part 54 is provided as a main vertex at the downstream (right side) position in the heat transfer direction indicated by the arrows in FIGS. 7 and 10, and the insertion parts 55 and 56 are respectively provided as base vertexes at positions upstream of the insertion part 54. Is provided.
These insertion portions 54 to 56 are formed so as to overlap the three recessed portions 31 d corresponding to the respective stacked bodies 50 when the stacked body 50 is fixed to the main body portion 31.
The insertion portions 54 to 56 include insertion holes 54 a to 56 a formed with a smaller diameter than the cylindrical portion 44 c of the heat conduction bolt 44, and slit portions 54 b to 56 b formed radially from the insertion holes 54 a to 56 a at intervals of 90 degrees. Respectively.
As shown in FIG. 10, the slit portion 54 b is formed in a cross shape in a direction parallel to and perpendicular to the heat transfer direction. The slit portions 55b and 56b are formed in an X shape so as to intersect the 45 ° direction and the 135 ° direction with respect to the heat transfer direction in order to ensure the maximum width of the heat conduction path. In the slit portions 54b to 56b, tearing prevention round portions are respectively formed at end portions opposite to the insertion holes 54a to 56a.
In addition, the insertion parts 55 and 56 are the same structures, and the insertion part 54 and the insertion parts 55 and 56 are the same structures except the installation direction (angle) of a slit part.

As shown in FIG. 11, the metal heat conduction bolt 44 includes a head portion 44a that can be fitted in a tightening tool (not shown), and a shaft portion 44b that is continuous with the head portion 44a.
The shaft portion 44b includes a cylindrical portion 44c that is continuous with the head portion 44a, and a screw portion 44d that is continuous with the cylindrical portion 44c and has a smaller diameter than the cylindrical portion 44c. The diameter of the cylindrical portion 44c is set to be larger than the diameter of the bolt hole 44h and smaller than twice the length of the slit portion. Accordingly, when the heat conduction bolt 44 is fastened to the bolt hole 44h via the insertion portions 54 to 56, the heat conduction bolt 44 directs the vicinity portions of the insertion holes 54a to 56a and the slit portions 54b to 56b in the fastening direction. Bend and proceed.
The axial length of the cylindrical portion 44c is set so that the pressing force from the heat conduction bolt 44 acting on the laminated body 50 becomes a predetermined pressure when the left end portion of the cylindrical portion 44c comes into contact with the bottom of the recessed portion 31d. Has been. Specifically, when the left end portion of the cylindrical portion 44c is in contact with the bottom portion of the recessed portion 31d and the fastening is completed, the pressing force is within a range of 100 to 700 kPa and does not cause the folding line 52a of the stacked body 50 to be completely bent. The axial length of the cylindrical portion 44c is defined.
A direction changing portion 44e having a sharp cross section is provided on the outer peripheral portion of the left end of the cylindrical portion 44c.

Next, the storage bag 60 will be described.
As shown in FIGS. 1, 2, and 4, the storage bag 60 presses the laminated body 50 with a uniform applied pressure from the thickness direction of the laminated body 50 in a filled state filled with pressurized air, The vertical wall portion of the stator core 21, the coil end 23, and the inner wall portion 31 c of the main body portion 31 are configured to be in surface contact with a uniform pressing force.
The storage bag 60 includes a ring-shaped bag portion 61 capable of storing pressurized air, a pipe-shaped introduction path 62 (pressurized air introduction path) connected to the bag section 61, and a bag section 61 There is provided a pressure regulating valve 63 that can be injected into the inside and can regulate the internal pressure to a predetermined pressure.

Bag part 61 mixes a fiber reinforcement in the main material, and the surface is surface-treated.
Main materials are predetermined heat and oil resistant rubber materials such as Si (silicon rubber), FKM (fluorine rubber), IIR (butyl rubber), EPDM (ethylene propylene rubber), CR (chloroprene rubber), NBR (nitrile rubber) Etc.
The fiber reinforcing material is aramid, steel wire, synthetic fiber or the like. The coating surface treatment is PEEK coating, polyimide coating, polyamideimide coating, or the like.

When the bag portion 61 is disposed in the space portion 33 in a non-filled state where the pressurized air is discharged, the introduction path 62 penetrates the valve openings 41b and 32b and protrudes to the outside.
The pressure regulating valve 63 attached to the leading end of the introduction path 62 is supplied with pressurized air from a pressurized air supply device (not shown), and the internal pressure of the bag unit 61 is set to a predetermined pressure, for example, +100 to the atmospheric pressure. The pressure is adjusted to +700 kPa. The storage bag 60 in a filled state filled with pressurized air is contact-regulated at three positions of the annular portion 41, the end portion 23 c of the large diameter portion 23 a and the vertical wall portion of the stator core 21 in the left-right direction. The directional position is abutted and restricted by two locations, the outer diameter portion 23 d of the large diameter portion 23 a and the inner wall portion 31 c of the main body portion 31. When the restriction of the vertical position by the outer diameter portion 23d of the large diameter portion 23a and the inner wall portion 31c of the main body portion 31 is removed due to factors such as impact or vibration, the cylindrical portion 42 supports the storage bag 60. The vertical position of 60 is maintained, and the storage bag 60 does not leave the space portion 33.

Next, the installation procedure of the laminated body 50 is demonstrated.
First, the rotor 10 and the stator 20 are assembled in the main body 31.
Next, in a state where the plurality of laminated bodies 50 are arranged in the circumferential direction in the space portion 33, the stepped portion 31 a and the inner wall portion 31 c of the main body portion 31, the vertical wall portion of the stator core 21, and the end portion of the coil end 23. The shape is adjusted so as to be along 23c and the outer diameter portion 23d.
For this reason, the folding line 52 a after the arrangement includes a portion that is parallel to the axis of the rotor shaft 11 and a portion that is orthogonal to the axis of the rotor shaft 11.

The insertion portions 54 to 56 of each stacked body 50 are positioned so as to overlap with a set of three recessed portions 31d corresponding to each stacked body 50, respectively.
In addition, when positioning the laminated body 50, a bending portion 50a that bulges excessively in the axial direction in the recess 24 is formed in advance. This is because damage to the laminated body 50 due to thermal contraction of the stator 20 and the housing 30 is alleviated by the bending portion 50a.

  Next, the accommodation bag 60 is inserted through the cylindrical portion 42 of the presser plate 40 and temporarily placed, and the plurality of heat conduction bolts 44 are inserted through the openings 41 a of the annular portion 41. At the same time, the introduction path 62 is inserted through the valve opening 41b. And after aligning the some heat conductive volt | bolt 44 which penetrated the annular part 41, and the insertion parts 54-56 of each laminated body 50, the fastening fixation to the level | step-difference part 31a of the several laminated body 50 is started.

When the heat conduction bolt 44 is inserted into the insertion portion 54 (55, 56) and the screw portion 44d is fastened to the bolt hole 44h, the direction changing portion 44e is a portion near the insertion hole 54a and the slit portion 54b of the laminate 50. Since it advances in the fastening direction (leftward) while dragging, the vicinity of the insertion hole 54a and the slit portion 54b is bent in the fastening direction and comes into close contact with the peripheral surface of the cylindrical portion 44c. Further, when the direction changing portion 44e exhibits a punch function, the direction changing portion 44e cuts the vicinity of the insertion hole 54a and the slit portion 54b and, as shown in FIG. 12, the scale-like graphite of the laminate 50. Is changed in the fastening direction, and the scaly graphite comes into surface contact with the peripheral surface of the cylindrical portion 44c in close contact.
Thereby, as shown by the arrow in FIG. 3, in addition to the heat transfer directly to the housing 30 by the laminated body 50, the laminated body 50 conducts heat to the housing 30 via the fixing heat conduction bolts 44 ( (See FIG. 3).

When the direction changing portion 44e reaches the bottom of the recessed portion 31d, the fastening of the heat conduction bolt 44 is completed. Since it acts on the laminated body 50 but is set to a predetermined pressure that is defined in advance, the laminated body 50 is fixed to the stepped portion 31a without being completely bent by the fold line 52a.
As a result, as shown by the arrows in FIG. 13, the amount of heat input to the lowermost layer of the stacked body 50 is transmitted to the uppermost layer via the folding line 52a, and this transmission form is repeated and transmitted to the uppermost layer. The Further, the amount of heat transmitted in the layer direction is sequentially transmitted to the layer immediately above by the surface contact structure of the insertion portions 54 to 56 by pressing of the heat conduction bolt 44, and is transmitted to the uppermost layer by repeating this transmission form. That is, the amount of heat input to the stacked body 50 is transmitted to the downstream side using all the layers of the stacked body 50.

Next, after aligning the bolt hole 34 h of the main body 31 and the end 32 a, the bolt 34 is fastened. At the same time, the introduction path 62 is inserted through the valve opening 32b.
Finally, pressurized air is supplied using a pressurized air supply device so that the pressure inside the storage bag 60 becomes a predetermined pressure. The plurality of laminated bodies 50 are uniform so as to be in surface contact with the stepped portion 31a and the inner wall portion 31c of the main body portion 31, the vertical wall portion of the stator core 21, and the end portion 23c and the outer diameter portion 23d of the coil end 23. Pressed with pressing force.
Since the stator coil 22 is a distributed winding method, the contact area (heat input area) between the coil end 23 and the laminated body 50 can be increased, and a direct heat conduction path from the coil end 23 to the housing 30 is ensured. Therefore, lubricating oil can be omitted.

  In the present embodiment, as shown in FIG. 1, the housing 30 and the metal base are connected by a laminate similar to the laminate 50. The amount of heat transferred from the coil end 23 to the housing 30 is transferred from the housing 30 by bolting the middle portion of the housing 30 and one end portion of the laminate, and bolting the base and the other end portion of the laminate. In addition to atmospheric radiation, heat is radiated directly to the base via the laminate.

Next, the operation and effect of the cooling structure of the electric motor 1 will be described.
According to the cooling structure of the electric motor 1, the cooling structure for heat exchange such as lubricating oil is omitted because it includes the plurality of stacked bodies 50 that are disposed in the space portion 33 and are each stacked with the plurality of graphene sheets 51. In addition, it is possible to dispose a plurality of stacked bodies 50 using the space portion 33 while maintaining the space portion 33 that is indispensable from the viewpoint of safety. Since the housing bag 60 containing the pressurized air that presses the plurality of laminated bodies 50 against the coil end 23 and the housing 30 from the thickness direction is provided, the coil end 23 and the housing 30 The graphene sheet 51 can be brought into surface contact with the coil end 23 with a uniform pressing force while securing an air insulating layer therebetween.

  Since the internal pressure of the storage bag 60 is set to 100 to 700 kPa, the superior heat conduction characteristics of the graphene sheet 51 can be reliably exhibited.

  The housing 30 includes an end portion 32 that closes the right-side opening end portion, and the storage bag 60 includes an introduction path 62 that extends through the end section 32 to the outside, and a pressure regulating valve 63 that is disposed at the tip of the introduction path 62. Is provided. Thereby, since the storage bag 60 can be assembled in an unfilled state, the assembly workability can be improved, and the storage bag 60 can be filled after assembly so that the pressure management of the storage bag 60 can be facilitated. it can.

  The laminated body 50 is formed by diffracting a plurality of intermediate laminated bodies 52 formed by laminating a plurality of graphene sheets 51 by folding lines 52a including folding lines 52a parallel to the axis of the rotor 10 on two parallel sides. Therefore, the heat conduction amount of the heat conduction path from the coil end 23 to the housing 30 can be increased regardless of the area occupied by the laminated body 50 with respect to the coil end 23 and the housing 30.

Next, a modified example in which the embodiment is partially changed will be described.
1] In the above embodiment, an example of a laminated body in which the intermediate laminated body is diffracted 28 times by two parallel folding lines has been described, but the number of folding of the intermediate laminated body may be arbitrarily set.
By reducing the thickness of the intermediate laminate, the number of foldings can be increased while keeping the thickness of the laminate constant, and the thermal conductivity of the laminate can be increased.
Moreover, although the example of the rectangular laminated body was demonstrated, a trapezoidal laminated body may be formed, and it may spread on the coil end radially without a gap.

2] In the above embodiment, the example of the distributed winding method has been described as the winding method of the stator coil. However, it may be applied to a concentrated winding type electric motor. As long as the laminate can be brought into surface contact with the coil end and the inner wall of the housing, it can be applied to any type of motor regardless of the type of the electric motor.

3] In the above-described embodiment, the extending portion is extended in one direction from one side long side of the lowermost intermediate laminate, and is extended in one side direction from one long side of the uppermost intermediate laminate. Although the example of the laminated body that can maintain the long shape by the connecting portion bonded to the extended portion has been described, as shown in FIG. 14, the extended portion is formed by the cutout portion cut out from the lowermost layer and the uppermost layer. May be. Thereby, the intermediate | middle laminated body (graphene sheet) used as a raw material can be made into a square, and a yield can be increased. Note that the width in the direction perpendicular to the long side of the cutout portion is formed to the minimum necessary to reduce the heat conduction path.

4] In the above embodiment, an example of an electric motor having only a heat conduction type dry cooling mechanism has been described. However, a cooling water passage may be formed in the housing, and a water cooling mechanism may be used in combination. Further, a fin or the like can be provided in the housing, and it can be used in combination with an air cooling mechanism.

5] In the above embodiment, the example in which the fiber reinforcing material is mixed into the main material of the bag portion of the storage bag has been described. However, the fiber reinforcing material may be omitted when the strength condition is satisfied. When the fiber reinforcing material is omitted, local tensile stress unevenness (starting point) in the bag portion is less likely to occur, and rupture of the bag portion can be suppressed.

6) In addition, those skilled in the art can implement the present invention in various forms added with various modifications without departing from the spirit of the present invention, and the present invention includes such modifications. is there.

DESCRIPTION OF SYMBOLS 1 Electric motor 10 Rotor 20 Stator 22 Stator coil 23 Coil end 30 Housing 32 End part 33 Space part 50 Laminate body 51 Graphene sheet 52 Intermediate laminate body 52a Folding line 60 Storage bag 62 Introduction path 63 Pressure regulation valve

Claims (4)

Electric motor cooling structure comprising a rotor, a stator around which a stator coil is wound, a housing for housing the rotor and the stator, and an insulating space formed between the housing and a coil end of the stator In
A plurality of laminated bodies arranged in the space for insulation and laminated with a plurality of graphene sheets, and
A cooling structure for an electric motor, comprising: a pressurized air containing bag containing pressurized air that presses the plurality of laminated bodies from the thickness direction against the coil end and the housing.   The cooling structure for an electric motor according to claim 1, wherein an internal pressure of the pressurized air storage bag is set to 100 to 700 kPa. The housing includes a housing end member that closes an axial end of the rotor;
The pressurized air storage bag is provided with a pressurized air introduction path extending through the housing end member to the outside, and a pressure regulating valve disposed at a tip of the pressurized air introduction path. The cooling structure of the electric motor according to claim 1 or 2.   The laminated body is configured such that an intermediate laminated body formed by laminating the plurality of graphene sheets is diffracted by a plurality of folding lines including folding lines parallel to the axis of the rotor on two parallel sides. The cooling structure for an electric motor according to any one of claims 1 to 3.