Hairpin winding motor and hairpin coil cooling structure

Abstract

The utility model relates to a hairpin winding motor and a hairpin coil cooling structure. More specifically, the present disclosure relates to a hairpin coil cooling structure for a hairpin winding motor, the hairpin winding motor including: a stator having a plurality of slots formed therethrough in a circumferential direction of the stator and each having a plurality of layers in a radial direction of the stator; a plurality of hairpin coils secured to the slots and connected to each other to define a coil winding, a rotor rotatably mounted within the stator; a rotor shaft, which is connected to the rotor; a pair of rotor plates disposed at first and second end portions of the rotor shaft, respectively, and configured to cover first and second opening sides of the stator; and a cooling oil injection pipe configured to inject cooling oil into the winding motor, the hairpin coil cooling structure being capable of improving cooling performance of the hairpin coil by injecting the cooling oil to a rotor plate that is a component of the motor and dispersing the cooling oil by rotating the rotor plate.

Description

Technical Field

[0001] The present disclosure 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 can improve the cooling performance of the hairpin coil by spraying oil onto a rotor plate as a component of the motor and dispersing the cooling oil by rotating the rotor plate. Background Art

[0002] Recently, research has been actively conducted to increase the output of motors, which are key components of hybrid or electric vehicles.

[0003] Generally, it is known that the output of a motor is proportional to the number of turns of the coil wound around a stator core. Therefore, a method of increasing the space factor of the coil wound around the stator core can be considered to increase the output of the motor without increasing the size of the motor.

[0004] Recently, as an example of this method, a method of winding an angular coil (flat coil) having an approximately quadrilateral cross-sectional shape instead of using a toroidal coil having a circular cross-section has been studied.

[0005] However, the operation of winding an angular coil is more difficult than the operation of winding a toroidal coil. Therefore, as a way to easily wind an angular coil, a motor (hereinafter, referred to as a "hairpin winding motor") has been proposed, in which a plurality of separate hairpins are inserted and fastened into a stator coil, and then the hairpins are joined by welding to define a coil winding portion.

[0006] Figure 1 A general hairpin winding motor 10 is shown. Figure 2 is a cross-sectional view showing a general hairpin winding motor 10. In the shown hairpin winding motor 10, a hairpin coil 13 formed in a substantially U-shape or V-shape is fastened into a slot of a stator core 12 provided in a housing 11, and then the hairpin coils 13 provided on the layers of the slots are joined and welded to form a coil winding portion of the stator core 12. Therefore, the hairpin winding motor 10 facilitates the operation of winding an angular coil while overcoming mechanical limitations caused by a winding machine.

[0007] At the same time, the housing 11 also includes a cooling oil injection pipe 15, and cooling oil is supplied into the housing 11 through the cooling oil injection pipe 15 to cool the heat-generating hairpin winding motor 10.

[0008] In the cooling structure for a hairpin-wound motor 10 of the prior art, due to rotor plates (not shown) provided on one opening side 12a and the other opening side 12b of the stator core 12, the cooling oil introduced into the housing 11 flows as shown by the arrows, and the cooling oil is only supplied to the radially outer side of the hairpin coils 13 and circulated, which causes a problem of deteriorated performance when cooling the coils provided radially inward.

[0009] In particular, it is necessary to develop a technique to prevent performance deterioration due to the temperature rise of the hairpin coils, because even if a large amount of heat is generated from the radially inner side of the hairpin coils adjacent to the rotor, the cooling method is biased toward the radially outer side. SUMMARY OF THE UTILITY MODEL

[0010] The present disclosure is proposed to solve these problems, and an object thereof is to provide a hairpin coil cooling structure for a hairpin-wound motor, which can improve the cooling performance of the radially inner coils adjacent to the rotor where the maximum amount of heat is generated in the hairpin coils.

[0011] Another object of the present disclosure is to provide a hairpin coil cooling structure for a hairpin-wound motor, which can inject cooling oil onto the rotor plate and rotate the rotor plate, so that the cooling oil dispersed by the rotation of the rotor plate is injected onto the inner coils.

[0012] An embodiment of the present disclosure provides a hairpin coil cooling structure for a hairpin-wound motor, the hairpin-wound motor including: a stator having a plurality of slots formed therethrough in the circumferential direction of the stator and each having a plurality of layers in the radial direction of the stator; and a plurality of hairpin coils fastened to the slots and connected to each other to define a coil winding, wherein the hairpin-wound motor includes: a rotor rotatably mounted within the stator; a rotor shaft connected to the rotor; a pair of rotor plates respectively provided at a first end and a second end of the rotor shaft and configured to cover a first opening side and a second opening side of the stator; and a cooling oil injection pipe configured to inject cooling oil into the winding motor, wherein a nozzle is provided at an end of the cooling oil injection pipe to inject the cooling oil onto an outer surface of the rotor plate, the nozzle being arranged to point to the outer surface of the rotor plate, and wherein the cooling oil injected onto the outer surface of the rotor plate is dispersed toward the inner coils located radially inside the stator in the hairpin coils by the rotation of the rotor plate.

[0013] In addition, the rotor plate may include: a circular main body portion having a center penetrated by the rotor shaft; a jet portion that protrudes outward from the outer surface of the circular main body portion, is formed at a radial center of the circular main body portion, and is formed along a circumferential direction of the circular main body portion; a jet groove that is formed in a radial inner surface of the jet portion and is recessed radially outward; and a jet hole that is formed in the jet groove and passes through the radial inner surface and the outer surface of the jet portion. A jet surface configured to jet the cooling oil may be formed on the outer surface of the circular main body portion, and the jet surface may be formed radially inside the jet portion.

[0014] In addition, the cooling oil injection pipe may further include an auxiliary nozzle that is formed on the cooling oil injection pipe and points to the inner coil to directly jet the supplied cooling oil to the inner coil.

[0015] In addition, the rotor plate may include: a circular main body portion having a center penetrated by the rotor shaft; a jet portion that protrudes outward from the outer surface of the circular main body portion, is formed at a radial center of the circular main body portion, and is formed along a circumferential direction of the circular main body portion; a first jet groove that is formed in a radial inner surface of the jet portion, is disposed adjacent to the outer surface of the circular main body portion, and is recessed radially outward; a second jet groove that is formed in the radial inner surface of the jet portion, is disposed spaced apart from the outer surface of the circular main body portion, and is recessed radially outward; a jet hole that is formed in the second jet groove and passes through the radial inner surface and the outer surface of the jet portion; a partition wall that is formed to separate the first jet groove and the second jet groove; and a connection groove that is formed in the partition wall such that the cooling oil distributed in the first jet groove moves to the second jet groove. A jet surface configured to jet the cooling oil may be formed on the outer surface of the circular main body portion, and the jet surface may be formed radially inside the jet portion.

[0016] In addition, the connection groove may be formed at a predetermined distance along the circumferential direction and be recessed radially inward. The connection groove may be formed adjacent to the jet hole, and a depth of the connection groove may be less than depths of each of the first jet groove and the second jet groove.

[0017] In addition, the jet hole may be disposed to be spaced apart from a position where the connection groove is formed by a first angle θ in a direction opposite to a rotation of the rotor plate.

[0018] In addition, the connection groove may be inclined at a second angle α with respect to the rotation axis of the rotor plate in the rotation direction of the rotor plate.

[0019] In addition, the cooling oil injection pipe may be connected to a lubricating oil injection pipe configured to inject lubricating oil into the winding motor, and the cooling oil may be the lubricating oil.

[0020] In addition, the injection holes may be provided as a plurality of injection holes spaced apart from each other in the circumferential direction of the injection part.

[0021] In addition, the auxiliary nozzles may be provided as a plurality of auxiliary nozzles spaced apart from each other in the longitudinal direction of the cooling oil injection pipe. Description of the Drawings

[0022] Figure 1 is a perspective view of a general hairpin winding motor.

[0023] Figure 2 is a cross-sectional view of a general hairpin winding motor.

[0024] Figure 3 is a front perspective view of a hairpin winding motor according to an embodiment of the present disclosure.

[0025] Figure 4 is a rear perspective view of a hairpin winding motor according to an embodiment of the present disclosure.

[0026] Figure 5 is a partially enlarged perspective view of a hairpin winding motor according to an embodiment of the present disclosure.

[0027] Figure 6A and Figure 6B are a perspective view and an inner cross-sectional view of a rotor plate according to a first embodiment of the present disclosure.

[0028] Figure 7 is a partially enlarged perspective view of a hairpin winding motor according to another embodiment of the present disclosure.

[0029] Figure 8 is a perspective view showing a cooling oil injection pipe according to another embodiment of the present disclosure.

[0030] Figure 9A and Figure 9B are a perspective view and an inner cross-sectional view of a rotor plate according to a second embodiment of the present disclosure.

[0031] Figure 10A and Figure 10B is a partially enlarged perspective view showing a cooling oil flow path of a rotor plate according to a second embodiment of the present disclosure.

[0032] Figure 11 is a partial enlarged front view of a rotor plate according to the third embodiment of the present disclosure.

[0033] Figure 12 is a partial enlarged perspective view of a rotor plate according to the fourth embodiment of the present disclosure.

[0034] Figure 13 is a partial enlarged perspective view of a hairpin winding motor according to the fifth embodiment of the present disclosure.

[0035] Figure 14 is a view showing the cooling performance of a hairpin winding motor according to an embodiment of the present disclosure.

[0036] Description of Reference Numerals

[0037] 100: Hairpin winding motor

[0038] 120: Stator

[0039] 130: Hairpin coil

[0040] 131: Hairpin outer coil

[0041] 132: Hairpin inner coil

[0042] 150, 150-1: Rotor plate

[0043] 151a: Injection surface

[0044] 151: Main body part

[0045] 152: Injection part

[0046] 153: Injection groove

[0047] 155: Injection hole

[0048] 160, 260: Cooling oil injection pipe

[0049] 265: Auxiliary nozzle

[0050] 190: Rotor shaft

[0051] 250: Rotor plate

[0052] 251: Main body part

[0053] 252: Injection part

[0054] 251a: Injection surface

[0055] 253: First injection groove

[0056] 254: Second injection groove

[0057] 255: Injection hole

[0058] 256: Partition wall

[0059] 257: Connection groove

[0060] 500: Lubricating oil injection pipe Detailed implementation mode

[0061] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0062] Figure 3 is a front perspective view of the hairpin winding motor 100 according to an embodiment of the present disclosure, Figure 4 is a rear perspective view of the hairpin winding motor 100 according to an embodiment of the present disclosure.

[0063] In the illustrated hairpin winding motor 100, the coil winding portion of the stator 120 is formed by fastening a hairpin coil 130 formed in a substantially "U" or "V" shape to the slot of the stator 120, and then joining and welding the hairpin coils 130 provided on the layers of the slot.

[0064] Meanwhile, a rotor (not shown) is rotatably installed inside the stator 120. The rotor shaft 190 is connected to the rotor. The rotor plate 150 is provided at one end of the rotor shaft 190 and covers one open side of the stator 120. The 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.

[0065] In this case, the present disclosure is characterized in that a part of the cooling oil introduced into the hairpin winding motor 100 is scattered toward the radially inner side of the hairpin coil 130 through the rotor plate 150 rotating together with the rotor shaft 190. The detailed configuration of the hairpin winding motor 100 for realizing the above features will be described in detail below with reference to the accompanying drawings.

[0066] Figure 5 is a partially enlarged perspective view of the hairpin winding motor 100 according to an embodiment of the present disclosure.

[0067] As Figure 5 shown, the rotor plate 150 is provided at one open side of the stator 120 and is connected to the rotor shaft 190. In addition, the winding motor 100 includes a cooling oil injection pipe 160 configured to supply cooling oil into the winding motor 100. The cooling oil injection pipe 160 has a nozzle formed at its end to supply (inject) the cooling oil to one surface 151a of the rotor plate 150, and the nozzle is provided to point to one surface of the rotor plate 150.

[0068] In this case, the following configuration is provided to supply the cooling oil supplied to one surface 151a of the rotor plate 150 to the inner coil 132 located radially inward in the hairpin coil 130.

[0069] Figure 6A and Figure 6B are a perspective view and an inner cross-sectional view of a rotor plate 150 according to a first embodiment of the present disclosure.

[0070] As shown in the figure, the rotor plate 150 includes: a plate-shaped circular main body 151 having a hollow portion formed at its center such that a rotor shaft penetrates the circular main body 151; and a jetting portion 152 protruding from one surface of the circular main body 151 toward one side. The jetting portion 152 is formed on a radially central portion of the circular main body 151 and is formed in a circumferential direction. A jetting groove 153 is formed in a radially inner surface of the jetting portion 152 and is recessed radially outward, and the jetting groove 153 is also formed in a circumferential direction. In addition, jetting holes 155 are formed in the jetting groove 153 and are formed through the radially inner surface and the radially outer surface of the jetting portion 152. The jetting holes 155 may be provided as a plurality of jetting holes 155 that are arranged to be spaced apart from each other in the circumferential direction.

[0071] Meanwhile, a jetting surface 151a is formed on one surface of the circular main body 151, and the jetting surface 151a may be formed radially inward of the jetting portion 152. Therefore, when the rotor plate 150 rotates, the cooling oil supplied to the jetting surface 151a through the cooling oil injection pipe 160 is distributed on the jetting groove 153 of the jetting portion 152 in the circumferential direction by centrifugal force, and the cooling oil is jetted toward the radially outer side of the jetting portion 152 through the jetting holes 155 in the circumferential direction. At the same time, since the inner coil 132 located radially inward in the hairpin coil 130 is disposed adjacent to the outer side of the rotor plate 150, the jetted cooling oil can be scattered toward the inner coil 132.

[0072] Figure 7 is a partially enlarged perspective view of a hairpin winding motor having a cooling oil injection pipe 260 according to another embodiment of the present disclosure. In addition, Figure 8 is a perspective view showing a cooling oil injection pipe 260 according to another embodiment of the present disclosure.

[0073] The rotor plate 150 is disposed on an opening side of the stator 120 and is connected to the rotor shaft 190. Additionally, the winding motor 100 includes a cooling oil injection pipe 260 configured to supply cooling oil into the winding motor 100. The cooling oil injection pipe 260 has a nozzle formed at its end to supply (inject) the cooling oil to a surface 151a of the rotor plate 150, and the nozzle is arranged to point to a surface of the rotor plate 150. In this case, the cooling oil injection pipe 260 according to another embodiment of the present disclosure has the following configuration to directly inject the supplied cooling oil into the inner coil 132 located radially inside the hairpin coil 130.

[0074] An auxiliary nozzle 265 may be further provided on the cooling oil injection pipe 260, and the auxiliary nozzle 265 is arranged to face the inner coil 132 located radially inside the hairpin coil 130. Additionally, the auxiliary nozzle 265 may be provided as a plurality of auxiliary nozzles 265, and these auxiliary nozzles 265 are arranged to be spaced apart from each other in the longitudinal direction of the cooling oil injection pipe 260. Therefore, in this embodiment, the cooling oil can be dispersed toward the inner coil 132 through the rotor plate 150, and at the same time, the cooling oil can be directly injected into the inner coil 132 through the auxiliary nozzle 265, thereby increasing the area of the cooling oil injected into the inner coil 132.

[0075] Figure 9A and Figure 9B are a perspective view and an inner cross-sectional view of the rotor plate 250 according to the second embodiment of the present disclosure, Figure 10A and Figure 10B are a partially enlarged perspective view showing the cooling oil flow path of the rotor plate 250 according to the second embodiment of the present disclosure.

[0076] As shown in the figure, the rotor plate 250 includes a plate-shaped circular main body portion 251 and a spraying portion 252. The circular main body portion 251 has a hollow portion formed at its center such that the rotor shaft penetrates the circular main body portion 251. The spraying portion 252 protrudes from a surface of the circular main body portion 151 toward one side. The spraying portion 252 is formed on the radially central portion of the circular main body portion 251 and is formed in the circumferential direction. A first spraying groove 253 and a second spraying groove 254 are formed in the radially inner surface of the spraying portion 252 and are recessed radially outward, and the first spraying groove 253 and the second spraying groove 254 are also formed in the circumferential direction. The first spraying groove 253 is disposed adjacent to a surface 251a of the circular main body portion 251, and the second spraying groove 254 is arranged to be spaced apart from the surface 251a. The first spraying groove 253 and the second spraying groove 254 are separated by a partition wall 256. Additionally, spraying holes 255 are formed in the second spraying groove 254 and are formed through the radially inner surface and the outer surface of the spraying portion 252. The spraying holes 255 may be provided as a plurality of spraying holes 255, and these spraying holes are arranged to be spaced apart from each other in the circumferential direction.

[0077] Meanwhile, the ejection surface 251a is formed on one surface of the circular main body portion 251, and the ejection surface 251a may be formed on the radially inner side of the ejection portion 252. Thus, when the rotor plate 250 rotates, the cooling oil supplied to the ejection surface 251a through the cooling oil injection pipe 160 is distributed in the circumferential direction on the first ejection groove 253 of the ejection portion 152 by centrifugal force. In this case, the connection groove 257 may be formed in the partition wall 256 such that when the cooling oil distributed in the first ejection groove 253 reaches a predetermined level, the cooling oil can move to the second ejection groove 254. The connection groove 257 may be formed at a predetermined distance in the circumferential direction and recessed radially inward. The position of the connection groove 257 may be adjacent to the ejection hole 255. Additionally, the depth of the connection groove 257 may be less than the depth of each of the first ejection groove 253 and the second ejection groove 254. When the cooling oil distributed in the first ejection groove 253 reaches a predetermined level, that is, becomes higher than the connection groove 257, the cooling oil moves to the second ejection groove 254 through the connection groove 257, and the cooling oil supplied to the second ejection groove 254 is ejected to the inner coil 132 through the ejection hole 255. According to the rotor plate 250 of the second embodiment, in a state where the cooling oil is uniformly distributed in the circumferential direction of the first ejection groove 253, the cooling oil can move to the second ejection groove 254 through the connection groove 257 and be ejected through the ejection hole 255, so that the cooling oil can be uniformly distributed to the plurality of ejection holes 255, thereby further improving the dispersion efficiency of the cooling oil.

[0078] Figure 11 is a partially enlarged front view of the rotor plate 250 according to the third embodiment of the present disclosure. As shown, the ejection holes 255 may be arranged at a first angle θ from the position where the connection groove 257 is formed in a direction opposite to the rotation of the rotor plate 250.

[0079] This is based on the fact that when the cooling oil moves to the second ejection groove 254 through the connection groove 257, the cooling oil accumulated in the first ejection groove 253 flows spirally due to the rotation of the rotor plate 250. Thus, the connection groove 257 and the ejection holes 255 may be arranged at a first angle from each other and not on a straight line in the radial direction. Therefore, the cooling oil that has moved to the second ejection groove 254 through the connection groove 257 can move to the ejection holes 255 along the shortest path.

[0080] Figure 12 is a partially enlarged perspective view of the rotor plate 250 according to the fourth embodiment of the present disclosure.

[0081] Considering the rotation direction of the rotor plate 250, the connection groove 257 may be inclined at a second angle α with respect to the rotation axis of the rotor plate 250. That is, considering the case where the cooling oil flows spirally due to the rotation of the rotor plate 250, the connection groove 257 may be formed to correspond to the spiral flow of the cooling oil, thereby improving the flow performance of the cooling oil.

[0082] Figure 13 FIG. is a partially enlarged perspective view of the hairpin winding motor 100 according to another embodiment of the present disclosure.

[0083] The cooling oil injection pipe 360 may be connected to the lubricating oil injection pipe 500, and the lubricating oil injection pipe 500 is configured to supply lubricating oil for lubricating the rotor bearing, and the cooling oil injection pipe 360 may be configured to inject the lubricating oil onto the injection surface 151a of the rotor plate 150. When the cooling oil injection pipe 360 is connected to a separate pipe to directly inject oil, the load of the pump may increase due to the pressure drop. Therefore, the cooling oil injection pipe 360 may be connected to the lubricating oil injection pipe 500 to lubricate the rotor bearing, thereby reducing the pressure drop.

[0084] Figure 14 FIG. is a view showing the cooling performance of the hairpin winding motor 100 according to an embodiment of the present disclosure. Light colors indicate high temperature, and dark colors indicate low temperature. As shown, it can be seen that in the case of the winding motor 100 of the present disclosure, the cooling oil is injected into the inner coil through the injection holes formed in the rotor plate 150, and the cooling oil is uniformly injected onto the inner coil by the rotation of the rotor plate 150.

[0085] In addition, it can be seen that the inner coil in the hairpin coil can be more effectively cooled through various embodiments, such as the size of the injection holes, the number of injection grooves, etc.

[0086] According to the hairpin coil cooling structure for a hairpin winding motor of the present disclosure configured as described above, the performance of cooling the relatively weak inner coil of the hairpin coil can be improved, thereby preventing the performance deterioration of the hairpin winding motor and improving the durability.

[0087] In addition, the basic configuration of the hairpin winding motor can be maintained, so that the hairpin coil cooling structure can be applied to the motors in the related art, thereby reducing the production cost or time, which can be increased by changing the production facilities and recycling resources.

[0088] The cooling oil dispersion flow rate or the cooling oil dispersion shape can be easily changed only by changing the shape of the rotor plate, thereby reducing the production cost or time, which can be increased by changing the layout of the motor.

[0089] The technical spirit should not be construed as being limited to the embodiments of the present disclosure. Of course, the scope of application is different, and those skilled in the art can make various modifications and implementations without departing from the subject matter of the present disclosure. Therefore, these improvements and modifications will fall within the scope of the present disclosure as long as they are obvious to those skilled in the art.

Claims

1. A hairpin winding motor, characterized in that, The hairpin winding motor includes: A stator having a plurality of slots formed therethrough in a circumferential direction of the stator and each having a plurality of layers in a radial direction of the stator; A plurality of hairpin coils fastened to the slots and connected to each other to define a coil winding; A rotor rotatably mounted within the stator; A rotor shaft connected to the rotor; A pair of rotor plates respectively disposed at a first end and a second end of the rotor shaft and configured to cover a first opening side and a second opening side of the stator; and A cooling oil injection pipe configured to inject cooling oil into the winding motor, wherein a nozzle is provided at an end of the cooling oil injection pipe to inject the cooling oil onto an outer surface of the rotor plate, the nozzle being arranged to point at the outer surface of the rotor plate, and wherein the cooling oil injected onto the outer surface of the rotor plate is dispersed toward inner coils located radially inside the stator among the hairpin coils by rotation of the rotor plate.

2. The hairpin winding motor according to claim 1, wherein The rotor plate includes: A circular main body having a center penetrated by the rotor shaft; A spraying portion protruding outward from an outer surface of the circular main body, formed at a radial center of the circular main body, and formed along a circumferential direction of the circular main body; A spraying groove formed in a radial inner surface of the spraying portion and recessed radially outward; and A spraying hole formed in the spraying groove and formed through the radial inner surface and the outer surface of the spraying portion, and wherein a spraying surface configured to spray the cooling oil is formed on the outer surface of the circular main body, and the spraying surface is formed radially inside the spraying portion.

3. The hairpin winding motor according to claim 1, wherein The cooling oil injection pipe further includes an auxiliary nozzle formed on the cooling oil injection pipe and pointing at the inner coils to directly inject the supplied cooling oil onto the inner coils.

4. The hairpin winding motor according to claim 1, characterized in that, The rotor plate includes: A circular main body having a center penetrated by the rotor shaft; A spraying portion protruding outward from an outer surface of the circular main body, formed at a radial center of the circular main body, and formed along a circumferential direction of the circular main body; A first spraying groove formed in a radial inner surface of the spraying portion, disposed adjacent to the outer surface of the circular main body, and recessed radially outward; A second spraying groove formed in the radial inner surface of the spraying portion, arranged to be spaced apart from the outer surface of the circular main body, and recessed radially outward; A spraying hole formed in the second spraying groove and formed through the radial inner surface and the outer surface of the spraying portion; A partition wall formed to separate the first spraying groove and the second spraying groove; and A connecting groove is formed in the partition wall such that the cooling oil distributed in the first injection groove moves to the second injection groove, and wherein an injection surface configured to inject the cooling oil is formed on the outer surface of the circular main body portion, and the injection surface is formed radially inward of the injection portion.

5. The hairpin winding motor according to claim 4, wherein The connecting groove is formed at a predetermined distance in the circumferential direction and recessed radially inward. The connecting groove is formed adjacent to the injection hole, and the depth of the connecting groove is less than the depth of each of the first injection groove and the second injection groove.

6. The hairpin winding motor according to claim 4, characterized in that, The injection hole is provided to be spaced apart from the position where the connecting groove is formed by a first angle in a direction opposite to the rotation of the rotor plate.

7. The hairpin winding motor according to claim 4, wherein The connecting groove is inclined at a second angle with respect to the rotation axis of the rotor plate in the rotation direction of the rotor plate.

8. The hairpin winding motor according to claim 1, wherein The cooling oil injection pipe is connected to a lubricating oil injection pipe configured to inject lubricating oil into the winding motor, and the cooling oil is the lubricating oil.

9. The hairpin winding motor according to claim 2, characterized in that The injection holes are provided as a plurality of injection holes, and the plurality of injection holes are provided to be spaced apart from each other in the circumferential direction of the injection portion.

10. The hairpin winding motor according to claim 3, wherein The auxiliary nozzles are provided as a plurality of auxiliary nozzles, and the plurality of auxiliary nozzles are provided to be spaced apart from each other in the longitudinal direction of the cooling oil injection pipe.

11. A hairpin coil cooling structure for a hairpin winding motor, the hairpin winding motor including a stator and a plurality of hairpin coils, the stator having a plurality of slots formed therethrough in a circumferential direction of the stator and each having a plurality of layers in a radial direction of the stator, the plurality of hairpin coils being fastened to the slots and connected to each other to define a coil winding, characterized in that, The hairpin coil cooling structure includes: a cooling oil injection pipe configured to inject cooling oil into the winding motor; and a nozzle provided at an end of the cooling oil injection pipe to inject the cooling oil onto the outer surface of the rotor plate, and the nozzle is provided to point to the outer surface of the rotor plate, wherein the cooling oil injected onto the outer surface of the rotor plate is scattered toward the inner coil located radially inside the stator in the hairpin coil by the rotation of the rotor plate.

12. The hairpin coil cooling structure according to claim 11, wherein, The hairpin coil cooling structure further includes: an injection portion protruding outward from the outer surface of the circular main body portion. The circular main body portion has a center penetrated by a rotor shaft. The injection portion is formed at the radial center of the circular main body portion and is formed in the circumferential direction of the circular main body portion; an injection groove formed in the radially inner surface of the injection portion and recessed radially outward; and an injection hole formed in the injection groove and formed through the radially inner surface and the outer surface of the injection portion, and wherein an injection surface configured to inject the cooling oil is formed on the outer surface of the circular main body portion, and the injection surface is formed radially inward of the injection portion.

13. The hairpin coil cooling structure according to claim 11, wherein, The cooling oil injection pipe further includes an auxiliary nozzle formed on the cooling oil injection pipe and pointing to the inner coil to directly inject the supplied cooling oil onto the inner coil.

14. The hairpin coil cooling structure according to claim 11, wherein The hairpin coil cooling structure further includes: an injection portion protruding outward from the outer surface of the circular main body portion. The circular main body portion has a center penetrated by a rotor shaft. The injection portion is formed at the radial center of the circular main body portion and is formed in the circumferential direction of the circular main body portion; The first injection groove is formed in the radially inner surface of the injection part, is disposed adjacent to the outer surface of the circular main body part, and is recessed radially outward; The second injection groove is formed in the radially inner surface of the injection part, is disposed to be spaced apart from the outer surface of the circular main body part, and is recessed radially outward; The injection hole is formed in the second injection groove and is formed through the radially inner surface and the outer surface of the injection part; The partition wall is formed to separate the first injection groove and the second injection groove; and The connection groove is formed in the partition wall such that the cooling oil distributed in the first injection groove moves to the second injection groove, and wherein, an injection surface configured to inject the cooling oil is formed on the outer surface of the circular main body part, and the injection surface is formed radially inside the injection part.

15. The hairpin coil cooling structure according to claim 14, wherein The connection groove is formed at a predetermined distance in the circumferential direction and is recessed radially inward. The connection groove is formed adjacent to the injection hole, and the depth of the connection groove is less than the depth of each of the first injection groove and the second injection groove.

16. The hairpin coil cooling structure according to claim 14, characterized in that, The injection hole is disposed to be spaced apart from the position where the connection groove is formed by a first angle in a direction opposite to the rotation of the rotor plate.

17. The hairpin coil cooling structure according to claim 14, wherein The connection groove is inclined at a second angle with respect to the rotation axis of the rotor plate in the rotation direction of the rotor plate.

18. The hairpin coil cooling structure according to claim 11, characterized in that, The cooling oil injection pipe is connected to a lubricating oil injection pipe configured to inject lubricating oil into the winding motor, and the cooling oil is the lubricating oil.

19. The hairpin coil cooling structure according to claim 12, characterized in that, The injection hole is provided as a plurality of injection holes, and the plurality of injection holes are disposed to be spaced apart from each other in the circumferential direction of the injection part.

20. The hairpin coil cooling structure according to claim 13, wherein, The auxiliary nozzles are provided as a plurality of auxiliary nozzles, and the plurality of auxiliary nozzles are disposed to be spaced apart from each other in the longitudinal direction of the cooling oil injection pipe.

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