Patent Application
20250079918
The present application claims priority to Korean Patent Application No. 10-2023-0117930, filed on Sep. 5, 2023, the entire contents of which are incorporated herein for all purposes by this reference.
The present invention relates to a cooling structure for a hairpin winding motor, and more particularly, to a hairpin coil cooling structure for a hairpin winding motor, which is capable of improving performance in cooling a hairpin coil by spraying oil to a rotor plate, which is a component of a motor, and dispersing the cooling oil by rotating the rotor plate.
Recently, studies have been actively conducted to improve an output of a motor that is a key component of a hybrid or electric vehicle.
In general, it is known that the output of the motor is proportional to the number of turns of a coil wound around a stator core. Therefore, a method of increasing a space factor of the coil wound around the stator core may be considered to improve the output of the motor without increasing a size of the motor.
Recently, as an example of the method, a method of winding an angular coil (flat coil) having an approximately quadrangular cross-sectional shape instead of using an annular coil having a circular cross-section has been studied.
However, it is more difficult to perform an operation of winding the angular coil than an operation of winding the annular coil. Therefore, as a way to make it easy to wind the angular coil, a motor (hereinafter, referred to as a ‘hairpin winding motor’) has been proposed, in which a plurality of separated hairpins is inserted and fastened into a stator coil, and then the hairpins are joined by welding to define a coil winding part.
Meanwhile, the housing 11 further includes an oil injection tube 15 through which cooling oil is supplied into the housing 11 to cool the hairpin winding motor 10 that generates heat.
In the cooling structure for the hairpin winding motor 10 in the related art, the cooling oil introduced into the housing 11 flows, as indicated by the arrows, because of rotor plates (not illustrated) disposed at one open side 12a and the other open side 12b of the stator core 12, and the cooling oil is supplied and circulated only to a radially outer side of the hairpin coil 13, which causes a problem of deterioration in performance in cooling the coil disposed radially inward.
In particular, there is a need to develop a technology to prevent deterioration in performance caused by an increase in temperature of the hairpin coil because the cooling method is biased to the radially outer side even though a large amount of heat is generated from a radially inner side of the hairpin coil adjacent to the rotor.
The present invention is proposed to solve these problems and aims to provide a hairpin coil cooling structure for a hairpin winding motor, which is capable of improving performance in cooling a radially inner coil, among hairpin coils, adjacent to a rotor that generates the largest amount of heat in the motor.
The present invention also aims to provide a hairpin coil cooling structure for a hairpin winding motor, which is capable of spraying cooling oil to a rotor plate and rotating the rotor plate so that the cooling oil dispersed by a rotation of the rotor plate is sprayed to an inner coil.
An embodiment of the present invention provides a hairpin coil cooling structure for a hairpin winding motor including a stator having a plurality of slots formed through the stator in a circumferential direction thereof and each having a plurality of layers in a radial direction thereof, and a plurality of hairpin coils fastened to the slots and connected to one another to define a coil winding, in which the winding motor includes: a rotor rotatably mounted inside the stator; a rotor shaft connected to the rotor; a pair of rotor plates respectively provided at a first end portion and a second end portion of the rotor shaft and configured to cover a first open side and a second open side of the stator; and an oil injection tube configured to spray a cooling oil into the winding motor, in which a nozzle, which is provided at an end of the cooling oil injection tube to spray the cooling oil to an outer surface of the rotor plate, is disposed to be directed toward the outer surface of the rotor plate, and in which the cooling oil sprayed to the outer surface of the rotor plate is scattered toward an inner coil, which is positioned at a radially inner side of the stator among the hairpin coils, by a rotation of the rotor plate.
In addition, the rotor plate may include: a circular body portion having a center penetrated by the rotor shaft; a spray portion protruding outward from an outer surface of the circular body portion, formed at a radially center of the circular body portion, and formed in a circumferential direction thereof; a spray groove formed in a radially inner surface of the spray portion and recessed radially outward; and a spray hole formed in the spray groove and formed through the radially inner surface and an outer surface of the spray portion, a spray surface configured to spray the cooling oil may be formed on the outer surface of the circular body portion, and the spray surface may be formed at a radially inner side of the spray portion.
In addition, the cooling oil injection tube may further include an auxiliary nozzle formed on the cooling oil injection tube and directed toward the inner coil to spray the supplied cooling oil directly to the inner coil.
In addition, the rotor plate may include: a circular body portion having a center penetrated by the rotor shaft; a spray portion protruding outward from an outer surface of the circular body portion, formed at a radially center of the circular body portion, and formed in a circumferential direction thereof; a first spray groove formed in a radially inner surface of the spray portion, disposed adjacent to the outer surface of the circular body portion, and recessed radially outward; a second spray groove formed in the radially inner surface of the spray portion, disposed to be spaced apart from the outer surface of the circular body portion, and recessed radially outward; a spray hole formed in the second spray groove and formed through the radially inner surface and an outer surface of the spray portion; a partition wall formed to separate the first spray groove and the second spray groove; and connection grooves formed in the partition wall so that the cooling oil distributed in the first spray groove moves to the second spray groove, a spray surface configured to spray the cooling oil may be formed on the outer surface of the circular body portion, and the spray surface may be formed at a radially inner side of the spray portion.
In addition, the connection grooves may be formed at predetermined distances in the circumferential direction and recessed radially inward, the connection groove may be formed adjacent to the spray hole, and a depth of the connection groove may be smaller than a depth of each of the first and second spray grooves.
In addition, the spray hole may be disposed to be spaced apart from a position, at which the connection groove is formed, by a first angle θ in a direction opposite to the rotation of the rotor plate.
In addition, the connection groove may be inclined at a second angle a with respect to a rotation axis of the rotor plate in a rotation direction of the rotor plate.
In addition, the cooling oil injection tube may be connected to a lubricating oil spray tube configured to inject lubricating oil into the winding motor, and the cooling oil may be the lubricating oil.
In addition, the spray hole may be provided as a plurality of spray holes disposed to be spaced apart from one another in the circumferential direction of the spray portion.
Further, the auxiliary nozzle may be provided as a plurality of auxiliary nozzles disposed to be spaced apart from one another in a longitudinal direction of the cooling oil injection tube.
Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings.
In the illustrated hairpin winding motor 100, a coil winding part of a stator 120 is formed by fastening hairpin coils 130, which are formed in an approximately ‘U’ or ‘V’ shape, into slots of the stator 120 and then joining and welding the hairpin coils 130 disposed on layers of the slots.
Meanwhile, a rotor (not illustrated) is rotatably mounted inside the stator 120. A rotor shaft 190 is connected to the rotor. A rotor plate 150 is provided at one end of the rotor shaft 190 and covers one open side of the stator 120. A rotor plate 150-1 is provided at the other end of the rotor shaft 190 and covers the other open side of the stator 120.
In this case, the present invention is characterized in that a part of oil introduced into the hairpin winding motor 100 is scattered toward a radially inner side of the hairpin coil 130 by the rotor plate 150 that rotates in conjunction with the rotor shaft 190. A detailed configuration of the hairpin winding motor 100 for implementing the above-mentioned characteristics will be described in detail with reference to the drawings.
As illustrated in
In this case, the following configuration is provided to supply the oil, which is supplied to one surface 151a of the rotor plate 150, to an inner coil 132 positioned at a radially inner side among the hairpin coils 130.
As illustrated, the rotor plate 150 includes a circular plate-shaped body portion 151 having a hollow portion formed at a center thereof so that the rotor shaft penetrates the circular body portion 151, and a spray portion 152 protruding from one surface of the circular body portion 151 toward one side. The spray portion 152 is formed on a radially central portion of the circular body portion 151 and formed in a circumferential direction. A spray groove 153 is formed in a radially inner surface of the spray portion 152 and recessed radially outward, and the spray groove 153 is also formed in the circumferential direction. In addition, spray holes 155 are formed in the spray groove 153 and formed through the radially inner surface and an outer surface of the spray portion 152. The spray holes 155 may be provided as a plurality of spray holes 155 disposed to be spaced apart from one another in the circumferential direction.
Meanwhile, a spray surface 151a is formed on one surface of the circular body portion 151, and the spray surface 151a may be formed at a radially inner side of the spray portion 152.
Therefore, when the rotor plate 150 rotates, the cooling oil supplied to the spray surface 151a through the cooling oil injection tube 160 is distributed in the circumferential direction on the spray groove 153 of the spray portion 152 by a centrifugal force, and the cooling oil is sprayed in the circumferential direction toward a radially outer side of the spray portion 152 through the spray holes 155. Meanwhile, because the inner coils 132 positioned at the radially inner side among the hairpin coils 130 are disposed adjacent to the outer side of the rotor plate 150, the sprayed oil may be scattered toward the inner coils 132.
The rotor plate 150 is provided at one open side of the stator 120 and coupled to the rotor shaft 190. In addition, the winding motor 100 includes the cooling oil injection tube 260 configured to supply cooling oil into the winding motor 100. The cooling oil injection tube 260 has a nozzle formed at an end thereof to supply (spray) the cooling oil to one surface 151a of the rotor plate 150, and the nozzle is disposed to be directed toward one surface of the rotor plate 150. In this case, the cooling oil injection tube 260 according to another embodiment of the present invention has the following configuration to spray the supplied cooling oil directly to the inner coil 132 positioned at the radially inner side among the hairpin coils 130.
Auxiliary nozzles 265 may be further provided on the cooling oil injection tube 260, and the auxiliary nozzles 265 are disposed toward the inner coil 132 positioned at the radially inner side among the hairpin coils 130. In addition, the auxiliary nozzles 265 may be provided as a plurality of auxiliary nozzles 265 disposed to be spaced apart from one another in a longitudinal direction of the cooling oil injection tube 260. Therefore, in the present embodiment, the cooling oil may be scattered toward the inner coil 132 by the rotor plate 150, and at the same time, the cooling oil may be sprayed directly to the inner coil 132 through the auxiliary nozzles 265, thereby increasing an area of the cooling oil sprayed to the inner coil 132.
As illustrated, the rotor plate 250 includes a circular plate-shaped body portion 251 having a hollow portion formed at a center thereof so that the rotor shaft penetrates the circular body portion 251, and a spray portion 252 protruding from one surface of the circular body portion 151 toward one side. The spray portion 252 is formed on a radially central portion of the circular body portion 251 and formed in the circumferential direction. First and second spray grooves 253 and 254 are formed in a radially inner surface of the spray portion 252 and recessed radially outward, and the first and second spray grooves 253 and 254 are also formed in the circumferential direction. The first spray groove 253 is disposed adjacent to one surface 251a of the circular body portion 251, and the second spray groove 254 is disposed to be spaced apart from one surface 251a. The first spray groove 253 and the second spray groove 254 are separated by a partition wall 256. In addition, spray holes 255 are formed in the second spray groove 254 and formed through the radially inner surface and an outer surface of the spray portion 252. The spray holes 255 may be provided as a plurality of spray holes 255 disposed to be spaced apart from one another in the circumferential direction.
Meanwhile, a spray surface 251a is formed on one surface of the circular body portion 251, and the spray surface 251a may be formed at a radially inner side of the spray portion 252. Therefore, when the rotor plate 250 rotates, the cooling oil supplied to the spray surface 251a through the cooling oil injection tube 160 is distributed in the circumferential direction on the first spray groove 253 of the spray portion 152 by a centrifugal force. In this case, connection grooves 257 may be formed in the partition wall 256 so that the cooling oil may move to the second spray groove 254 when the cooling oil distributed in the first spray groove 253 reaches a predetermined level. The connection grooves 257 may be formed at predetermined distances in the circumferential direction and recessed radially inward. A position of the connection groove 257 may be adjacent to the spray hole 255. In addition, a depth of the connection groove 257 may be smaller than a depth of each of the first and second spray grooves 253 and 254. In case that the cooling oil distributed in the first spray groove 253 reaches a predetermined level, i.e., becomes higher than the connection groove 257, the cooling oil moves to the second spray groove 254 through the connection groove 257, and the cooling oil supplied to the second spray groove 254 is sprayed to the inner coil 132 through the spray hole 255. According to the rotor plate 250 of the second embodiment, in a state in which the cooling oil is distributed uniformly in the circumferential direction of the first spray groove 253, the cooling oil may be moved to the second spray groove 254 through the connection grooves 257 and sprayed through the spray holes 255, such that the cooling oil may be uniformly distributed to the plurality of spray holes 255, thereby further improving efficiency in scattering the oil.
This is based on the fact that the oil, which accumulates in the first spray groove 253, spirally flows by the rotation of the rotor plate 250 when the cooling oil moves to the second spray groove 254 through the connection groove 257. Therefore, the connection groove 257 and the spray hole 255 may be disposed to be spaced apart from each other by the first angle without being positioned on a straight line in the radial direction. Therefore, the oil, which has moved to the second spray groove 254 through the connection groove 257, may move to the spray hole 255 along the shortest route.
The connection groove 257 may be inclined at a second angle a with respect to a rotation axis of the rotor plate 250 in consideration of the rotation direction of the rotor plate 250. That is, in consideration of the situation in which the cooling oil spirally flows by the rotation of the rotor plate 250, the connection groove 257 may be formed to correspond to the spiral flow of the oil, thereby improving the flow performance of the oil.
An oil injection tube 360 may be connected to a lubricating oil spray tube 500 configured to supply lubricating oil for lubricating a rotor bearing, and the cooling oil injection tube 360 may be configured to spray the lubricating oil to the spray surface 151a of the rotor plate 150. In case that the cooling oil injection tube 360 is connected to a separate tube to directly spray the oil, a load of a pump may be increased by a pressure drop. Therefore, the cooling oil injection tube 360 may be connected to the lubricating oil spray tube 500 for lubricating the rotor bearing, thereby reducing a pressure drop.
In addition, it can be seen that it is possible to more effectively cool the inner coil, among the hairpin coils, by means of various embodiments such as the sizes of the spray holes, the number of spray grooves, and the like.
According to the hairpin coil cooling structure for a hairpin winding motor of the present invention configured as described above, the performance in cooling the relatively weak inner coil of the hairpin core may be improved, thereby preventing the deterioration in performance of the hairpin winding motor and improving the durability.
In addition, the basic configuration of the hairpin winding motor may be maintained, such that the hairpin coil cooling structure may be applied to a motor in the related art, thereby reducing production costs or time, which may be increased by a change in production facilities, and recycling resources.
The cooling oil scattering flow rate or the cooling oil scattering shape may be easily changed only by changing the shape of the rotor plate, thereby reducing production costs or time that may be increased by a change in layouts of the motor.
The technical spirit should not be construed as being limited to the embodiments of the present invention. Of course, the scope of application is diverse, and various modifications and implementations may be made by those skilled in the art without departing from the subject matter of the present invention claimed in the claims. Accordingly, these improvements and modifications will fall within the scope of the present invention as long as they are apparent to those skilled in the art.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2023-0117930 | Sep 2023 | KR | national |
