JP7208350B2 - Electric motor with improved heat dissipation and productivity, and method for manufacturing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electric motor and its manufacturing method, and more particularly to an electric motor with improved heat dissipation and productivity and its manufacturing method.

A temperature rise due to heat generation in the windings is directly linked to a drop in the continuous rated torque of the motor. Therefore, how to dissipate the heat of the windings to the outside is an important issue. Known techniques for improving the heat dissipation of windings include, for example, a resin molding method in which the entire winding is covered with resin, and a method that relies solely on a winding impregnating agent that fills the gap between the winding and the stator core. ing.

FIG. 8 is a schematic diagram showing an example of an electric motor 50 in which heat dissipation is enhanced by a mold resin 51. As shown in FIG. The mold resin 51 is produced by loading the stator core 53 wound with the windings 52 into a special mold (not shown) and injection molding molten resin into the mold. The heat of the windings 52 generated when the electric motor 50 is driven is transferred from the mold resin 51 to the stator core 53 and released to the outside.

FIG. 9 is a schematic diagram showing an example of an electric motor 60 that relies only on a winding impregnating agent 61 such as varnish for heat dissipation of windings. Although the winding impregnating agent 61 is originally used to harden the windings 62 , it also fills the gap between the windings 62 and the stator core 63 , thereby enhancing heat transfer from the windings 62 to the stator core 63 .

As other prior art related to the present application, the following documents are also known. Patent Literature 1 discloses that a mold resin is brought into contact with a winding and a cylindrical portion of a cooling member. In particular, the mold resin penetrates into the grooves formed on the inner peripheral surface of the cylindrical portion to increase the contact area between the windings and the cooling member.

Patent Literature 2 discloses bringing a resin molded body into contact with the winding and the upper bearing housing.

Patent Literature 3 discloses that the mold resin is brought into contact with the coil ends and the case.

Patent Document 4 discloses a molded stator in which resin portions are brought into contact with coils and end plate portions.

Patent Literature 5 discloses bringing resin into contact with the stator windings and the end cover. Furthermore, a high heat conductive sheet having a heat conductivity of 400 W/m·K or more is integrally formed in the resin.

Patent Literature 6 discloses a motor in which high thermal conductivity resin is molded between a coil and a frame to improve heat dissipation while maintaining insulation characteristics.

Patent Literature 7 discloses a rotating machine in which resin forming an end mold is brought into contact with coil ends and a motor frame. Furthermore, the resin is mixed with a filler having a high thermal conductivity.

Patent Document 8 discloses an electric motor in which a resin mold is brought into contact with a field coil and a case. The mold is also in contact with the coolant channels.

Patent Document 9 discloses an electric motor in which a sheet of resin material having high thermal conductivity is sandwiched between a winding end and a bracket.

Patent Document 10 discloses filling a space between a drive coil and a holder or a housing with a thermally conductive resin to improve heat dissipation. The thermally conductive resin faces the air gap between the stator and rotor, so it is presumed to be molded.

JP 2018-82517 A JP 2018-26920 A JP 2016-46832 A JP-A-2014-7801 JP 2011-205775 A JP 2011-139555 A JP 2007-143245 A JP 2008-167609 A JP-A-2002-369449 JP-A-5-328686

The resin molding method requires various steps of injection molding of resin, resulting in a long manufacturing period. In addition, there is also the problem of high manufacturing costs due to the need for special molds, injection molding machines, and the like. On the other hand, those that rely only on winding impregnating agents cause a decrease in rated torque due to insufficient heat dissipation.

Therefore, there is a demand for a technique for improving heat dissipation and productivity of an electric motor by a simple method.

One aspect of the present disclosure includes a housing having an annular groove on an inner surface, a winding wound around a stator core and having a coil end projecting axially from the stator core disposed in the annular groove, and a coil filled in the annular groove. a heat-conducting resin contacting both the end and the housing, the housing having a resin filling path communicating from the annular groove to the outer surface of the housing for filling the heat-conducting resin from outside the electric motor into the annular groove; Provided is an electric motor in which a resin-filled passage extends in a direction inclined with respect to the radial direction of a housing.
Another aspect of the present disclosure is to form an annular groove in the inner surface of the housing, form a resin filling path communicating from the annular groove to the outer surface of the housing and extending in a direction inclined with respect to the radial direction of the housing, A winding is wound around a stator core to form a coil end protruding axially from the stator core, the stator core is assembled to a housing, the coil end is arranged in an annular groove, and a heat-conducting resin is annularly filled through a resin filling passage. Provided is a method for manufacturing an electric motor, in which heat-conducting resin contacts both coil ends and a housing by filling grooves.

According to one aspect of the present disclosure, it is possible to improve not only the heat dissipation of the electric motor but also the productivity by a simple technique of filling the annular groove of the front housing with the heat conductive resin.

1 is a cross-sectional view of an electric motor in one embodiment; FIG. It is an expanded sectional view of thermally-conductive resin in one Embodiment. It is an exploded view showing a manufacturing method of an electric motor in one embodiment. It is an exploded view showing a manufacturing method of an electric motor in other embodiments. It is a sectional view of the electric motor in another embodiment. FIG. 10 is an internal view of the front housing in another embodiment; FIG. 10 is an interior view of the front housing in yet another embodiment; 1 is a sectional view of an electric motor in the prior art; FIG. FIG. 3 is a cross-sectional view of an electric motor in another prior art;

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In each drawing, the same or similar components are given the same or similar reference numerals. Moreover, the embodiments described below do not limit the technical scope of the invention described in the claims and the meaning of the terms. Note that in this specification the term "forward" means the load, output side of the motor, and the term "rear" means the anti-load, anti-output side of the motor.

FIG. 1 is a cross-sectional view of an electric motor 10 according to this embodiment. The electric motor 10 in this example is, for example, a servomotor, but it should be noted that other electric motors can also be used as long as the stator has windings. The electric motor 10 includes a stator 11 , a rotor 12 arranged inside the stator 11 in the radial direction Y, and a detector 13 for detecting the position, speed, etc. of the rotor 12 .

The stator 11 includes a stator core 15 around which windings 14 are wound, and a front housing 16 and a rear housing 17 assembled to the stator core 15 . On the other hand, the rotor 12 may comprise a squirrel cage rotor, a wound rotor, a permanent magnet rotor, or the like. The rotor 12 includes an output shaft 18 supported by bearings (not shown), a rotor core 19 assembled to the output shaft 18, and a detection disk 13a assembled to the rear of the output shaft 18. . The detector 13 can be composed of a detector such as an encoder, resolver, Hall element, tachogenerator, or the like. The detector 13 detects the position, speed, etc. of the rotor 12 based on the detection disk 13a.

The front housing 16 is made of silicon iron, stainless steel, other alloys, or the like having high thermal conductivity and magnetic permeability. A front housing 16 is arranged on the load side and has an annular groove 16a on its inner surface. The winding 14 has coil ends 14 a and 14 b projecting forward and backward from the stator core 15 . A forwardly projecting coil end 14 a is disposed within an annular groove 16 a of the front housing 16 . A thermal conductive resin 22 is filled in the annular groove 16a. The heat conductive resin 22 is in contact with both the coil ends 14 a and the front housing 16 . As a result, the heat of the coil ends 14a generated when the electric motor 10 is driven is transferred to the front housing 16 and released from the front housing 16 to the outside.

In addition, since the thermally conductive resin 22 only needs to be filled into the annular groove 16a (so as not to protrude from the annular groove 16a) manually or mechanically, various steps of injection molding are not required, and expensive special metals are required. Manufacturing facilities such as molds and injection molding machines are not required. Therefore, the manufacturing period can be shortened, and the manufacturing cost can be reduced. As a result, the productivity of the electric motor 10 is improved. An annular groove may be provided in the rear housing 17 and the heat conductive resin 22 may be filled in the annular groove. As a result, the heat of the coil end 14b protruding rearward is transferred to the rear housing 17 and released from the rear housing 17 to the outside.

Further, the electric motor 10 may be provided with an impregnating resin 23 such as varnish applied to the windings 14 . The impregnated resin 23 not only fills the gaps between the windings to fix the windings 14, but also fills the gaps between the windings 14 and the stator core 15. Furthermore, the heat is transferred to the front housing 16 and is easily released to the outside. According to the impregnating resin 23, existing manufacturing equipment, existing manufacturing materials, etc. can be used, so that the manufacturing cost can be further reduced. Moreover, it is preferable that the impregnated resin 23 is in contact with the thermal conductive resin 22 . As a result, the heat of the windings 14 is radiated from the impregnated resin 23 to the thermally conductive resin 22, from the thermally conductive resin 22 to the front housing 16, and further from the front housing 16 to the outside, thereby further improving heat dissipation. In addition, the impregnating resin 23 preferably has the same composition as the thermally conductive resin 22 . As a result, the contact heat resistance at the contact interface between the heat-conducting resin 22 and the impregnating resin 23 is reduced, and the heat transferability is further enhanced.

FIG. 2 is an enlarged cross-sectional view of the thermally conductive resin 22 in this embodiment. The thermally conductive resin 22 of the present example includes interconnected insulating thermally conductive fibers 25 within a matrix resin 24 . As the matrix resin 24, heat-resistant resins such as thermosetting resins such as polyimide resins, silicon resins, epoxy resins, and phenol resins, or thermoplastic resins such as polyphenylene sulfide resins, polycarbonate resins, polybutylene terephthalate resins, and polyacetal resins can be used. Resins may be mentioned. Aluminum nitride, magnesium oxide, boron nitride, alumina, anhydrous magnesium carbonate, silicon oxide, zinc oxide, or the like can be used as the insulating heat-conducting fiber 25 .

The insulating heat-conducting fibers 25 are shaped like rods, flakes, scales, etc., and by adding a large amount to the matrix resin 24, they are interconnected in the matrix resin 24 and oriented in the axial direction X. can be made with As a result, the heat generated at the coil ends 14 a is transferred in the heat transfer direction H through the interconnected insulating heat-conducting fiber network, and is easily transferred to the front housing 16 . Since the heat-conducting resin 22 only needs to be filled into the annular groove 16a manually or mechanically, it does not require injection molding in which the resin is injected under high pressure, and does not require high fluidity. Therefore, the particle size, weight ratio, etc. of the insulating heat-conducting fibers 25 are increased, and it is easy to form an interconnected state. Instead of the insulating heat-conducting fiber 25, an insulating heat-conducting filler shaped like a granule or a sphere may be added to the matrix resin 24. FIG.

FIG. 3 is an exploded view showing a method of manufacturing the electric motor 10 according to this embodiment. In the first step, an annular groove 16a is formed in the inner surface 16b of the front housing 16 located on the load side. The front housing 16 is formed by die casting, machining, or the like. In the second step, the annular groove 16a is filled with a gelled or melted thermal conductive resin 22 in the filling direction F1. In the third step, winding 14 is wound around stator core 15 to form coil end 14 a protruding forward from stator core 15 . In the fourth step, the front housing 16 is assembled to the stator core 15 and the coil ends 14a are arranged in the annular grooves 16a, so that the heat conductive resin 22 contacts both the coil ends 14a and the front housing 16. As shown in FIG. Subsequently, when the thermally conductive resin 22 is a thermosetting resin, the front housing 16 is heated to solidify the thermally conductive resin 22 . Alternatively, if the thermally conductive resin 22 is a thermoplastic resin, the front housing 16 is cooled to solidify the thermally conductive resin 22 . As described above, there is no need for various injection molding processes, expensive dedicated molds, injection molding machines, and the like. The rotor 12, the rear housing 17, and the detector 13 may be assembled before or after the heat conductive resin 22 is solidified.

FIG. 4 is an exploded view showing a method of manufacturing the electric motor 10 according to another embodiment. This example differs from the manufacturing method described above in that the heat conductive resin 22 is filled into the annular groove 16a from behind the stator core 15 after the front housing 16 is assembled to the stator core 15 . Specifically, in the first step, an annular groove 16a is formed in the inner surface of the front housing 16 arranged on the load side. In the second step, winding 14 is wound around stator core 15 to form coil ends 14a. In the third step, the front housing 16 is assembled to the stator core 15 and the coil ends 14a are arranged in the annular grooves 16a. In the fourth step, gelled or melted thermally conductive resin 22 is filled into the annular groove 16a from behind the stator core 15 in the filling direction F2, so that the thermally conductive resin 22 contacts both the coil ends 14a and the front housing 16. . According to this manufacturing method, the heat conductive resin 22 is filled in the annular groove 16a while the coil ends 14a and the front housing 16 are positioned in the annular groove 16a. 16 are easily accessible. In addition, further subsequent steps are the same as the manufacturing method described above, so description thereof will be omitted.

FIG. 5 is a cross-sectional view of electric motor 30 in another embodiment, and FIG. 6 is an internal view of front housing 36 . The electric motor 30 of this example differs from the electric motor 10 described above in that it includes a resin-filled passage 36c communicating from the annular groove 36a to the outer surface 36b of the front housing 36. As shown in FIG. The resin filling passage 36 c is formed by die casting, machining, or the like, and extends in the radial direction Y of the front housing 36 . Since the resin filling path 36c is a filling path for the heat-conducting resin 22, it is preferable that a plurality of resin-filling paths 36c, such as three or four, be provided so that the heat-conducting resin 22 spreads over the entire annular groove 36a. Further, the resin filling passage 36c can be used as a cooling passage for cooling the heat conducting resin 22 and the front housing 36 since the resin filling passage 36c can access the heat conducting resin 22 even after filling. A cooling device (not shown) is connected to the cooling path. As a cooling device, an air-cooling type such as a cooling fan, a cooler, a radiator, or the like, a water-cooling type, an oil-cooling type, or the like can be used.

The manufacturing method of the electric motor 30 is different from the manufacturing method described above in that the heat conductive resin 22 is filled into the annular groove 36a through the resin filling passage 36c. Specifically, in the first step, an annular groove 36a is formed in the inner surface of the front housing 36 arranged on the load side. In the second step, a resin filling passage 36c communicating from the annular groove 36a to the outer surface 36b of the front housing 36 is formed. In the third step, winding 14 is wound around stator core 15 to form coil end 14 a protruding forward from stator core 15 . In the fourth step, the stator core 15 is assembled to the front housing 36 and the coil ends 14a are arranged in the annular grooves 36a. In the fifth step, rotor 12, rear housing 17, and detector 13 are assembled. In the sixth step, the heat conductive resin 22 is filled in the annular groove 36a in the filling direction F3 through the resin filling path 36c, so that the heat conductive resin 22 contacts both the coil end 14a and the front housing 36. As shown in FIG. Subsequently, the thermal conductive resin 22 is solidified in the same manner as described above. Note that the fifth step may be performed after the thermal conductive resin 22 is filled.

FIG. 7 is an interior view of the front housing 46 in yet another embodiment. The resin filling path 46 c of this example extends in a direction inclined with respect to the radial direction Y of the front housing 46 . As a result, the heat conductive resin 22 can easily spread over the entire annular groove 46a. In addition, as described above, the resin filling passage 46c may be used as a cooling passage for cooling the heat conducting resin 22 and the front housings 36,46. Since the resin filling passage 46c is inclined with respect to the radial direction Y of the front housing 46, when the refrigerant is gas, it easily flows in the circumferential direction through the annular groove 46a.

In the various embodiments described above, the front housing 16, 36, 46 preferably contacts a heat dissipating member (not shown) to which the motor is mounted. Examples of the heat dissipation member include metallic structural members, heat sinks, and the like. Thereby, the heat dissipation of the electric motor 10 is further improved.

According to the above-described embodiment, not only heat dissipation of the electric motor but also productivity can be improved by a simple method of filling only the annular grooves 16a, 36a, 46a of the front housings 16, 36, 46 with the heat conductive resin 22. can be done.

Although various embodiments have been described herein, it is recognized that the invention is not limited to the embodiments described above and that various modifications can be made within the scope of the following claims. want to be

Reference Signs List 10, 30 Electric motor 11 Stator 12 Rotor 13 Detector 13a Detecting disk 14 Winding 14a, 14b Coil end 15 Stator core 16, 36, 46 Front housing 16a, 36a, 46a Annular groove 16b Inner surface 17 Rear housing 18 Output shaft 22 Heat Conductive resin 23 Impregnated resin 24 Matrix resin 25 Insulating thermally conductive fiber 36b, 46b Outer surface 36c, 46c Resin filling path

Claims (8)

a housing having an annular groove on its inner surface;
a winding wound around a stator core and having a coil end projecting axially from the stator core disposed in the annular groove;
a thermally conductive resin filled in the annular groove and in contact with both the coil end and the housing;
with
The housing has a resin filling path that communicates with the outer surface of the housing from the annular groove for filling the heat conductive resin from the outside of the electric motor into the annular groove,
An electric motor according to claim 1, wherein said resin filling path extends in a direction inclined with respect to a radial direction of said housing. The electric motor according to claim 1, further comprising an impregnated resin that fills a gap between the windings and the stator core. 3. The electric motor of claim 2, wherein said impregnating resin contacts said thermally conductive resin. 4. The electric motor according to claim 2, wherein said impregnating resin has the same components as said thermally conductive resin. 5. The electric motor of any one of claims 1 to 4, wherein the thermally conductive resin comprises interconnected insulating thermally conductive fibers. The electric motor according to any one of claims 1 to 5, wherein the housing contacts a heat dissipating member to which the electric motor is mounted. 2. The electric motor according to claim 1, wherein said resin-filled path is used as a cooling path for cooling said thermally conductive resin and said housing. forming an annular groove on the inner surface of the housing,
forming a resin filling path communicating from the annular groove to the outer surface of the housing and extending in a direction inclined with respect to the radial direction of the housing;
winding a winding around a stator core to form a coil end projecting axially from the stator core;
assembling the stator core to the housing and arranging the coil end in the annular groove;
A method of manufacturing an electric motor, wherein the heat conductive resin is brought into contact with both the coil ends and the housing by filling the annular groove with a heat conductive resin from the outside of the electric motor through the resin filling path. .

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