Cooling mechanism for drive motor

Abstract

Cooling mechanism for a drive motor, the mechanism comprising: a cylindrical stator wound with a coil and comprising a first and a second side; a cylindrical motor housing having a sealed first side and an open second side and receiving the stator therein; a snap ring fitted into an inner peripheral surface of the second side of the motor housing to have a radially inner side projecting inward from the inner peripheral surface of the motor housing, and securing the second side of the stator by having a surface projecting and in contact with a periphery of a surface of the stator; and an oil supply path formed between an outer peripheral surface of the stator and the inner peripheral surface of the motor housing for supplying oil to the snap ring through the oil supply path, wherein the snap ring includes an oil spray path having an upstream side in fluid communication with the oil supply path and a downstream side passing through an inner peripheral surface of the snap ring and exposed to the second side of the stator.

Description

Technical area

[0001] The following disclosure relates to a drive motor having a cooling mechanism for directly cooling the drive motor using cooling oil, and more particularly to a cooling mechanism for a drive motor that sprays the cooling oil onto a stator by using a snap ring to secure the stator to a motor housing. background

[0002] A drive motor used in an electric vehicle (EV) or a hybrid vehicle (HEV) can improve fuel efficiency from a vehicle perspective if the motor has higher power at the same weight and size. However, for the drive motor to have higher power, it may be necessary to increase a current, i.e., the input power. However, when the current flows through a coil inside the motor, heat may be generated due to coil resistance. Therefore, it is necessary to reduce the heat generated in the drive motor.

[0003] Methods for cooling the coil inside the drive motor can be roughly divided into three types. A first method may be an air cooling method using a cooling fin exposed to the outside, and a second method may be a water cooling method in which the coil is indirectly cooled by forming a water path in a casing or the like. A third method may be an oil cooling method in which oil, which is an insulating material, is used to directly cool the coil inside the motor.

[0004] Recently, the number of cases using a drive motor that uses a direct cooling method using the cooling oil has increased in accordance with the continuously increasing demand for a highly efficient and powerful drive motor for the development of a high-performance electric vehicle.

[0005] There are two methods for directly cooling the engine's interior. One is the agitation method, which injects an appropriate amount of oil into the engine and pumps the oil through a rotating body. The other is the spray method, which flows or sprays the oil from top to bottom.

[0006] As in Fig. As shown in Figure 1, the spray type may supply oil to a cooling oil line 11 to intensively spray the cooling oil onto a stator assembly 10, and form an oil spray hole 13 at one end of the line 11 to spray the oil onto a target. The sprayed oil may flow through a coil 15 of the stator assembly 10. In this case, the sprayed oil may fall downward because the oil flows by gravity under a condition where the engine is mounted on the vehicle.

[0007] Meanwhile, the stator assembly 10 of the drive motor may have a circular shape, and therefore the oil sprayed from above can only flow downward and stay near the spray hole 13, thereby limiting a cooling area.

[0008] To solve this limitation / problem, a conventional technology has been publicly disclosed which includes an oil guide for spraying the oil by dividing the oil into a plurality of paths, whereby the oil flowing into the oil guide can be evenly sprayed onto the stator assembly 10.

[0009] A conventional cooling structure of the drive motor including the oil guide as described above may further include the oil guide configuration acting as a resistance to oil flow and thus causing an insufficient effect on increasing the cooling efficiency, and may require additional processes for manufacturing and assembling the oil guide, thereby increasing both its manufacturing cost and its process cost. Summary

[0010] An embodiment of the present disclosure aims to provide a cooling mechanism for a drive motor, in which an oil path and a spray hole are formed in a snap ring for securing a stator inserted into a motor housing, and an oil supply groove is formed between the motor housing and the stator so that one end of the groove communicates with the oil path of the snap ring, thereby supplying cooling oil to the stator using the snap ring.

[0011] From a general aspect, there is provided a cooling mechanism for a drive motor, the mechanism comprising: a cylindrical stator wound with a coil; a cylindrical motor housing having a sealed first side and an open other side and accommodating the stator therein; a snap ring fitted into an inner peripheral surface of the other side of the motor housing so that a radially inner side protrudes inward from the inner peripheral surface of the motor housing, and securing the other side of the stator by having a surface that protrudes and contacts a periphery of the other surface of the stator;and an oil supply path formed between an outer peripheral surface of the stator and the inner peripheral surface of the motor housing for supplying oil to the snap ring, wherein the snap ring includes an oil spray path having an upstream side fluidly connected to the oil supply path and a downstream side passing through an inner peripheral surface of the snap ring and exposed to the other side of the stator;

[0012] The oil supply path may be formed in an axial direction, have a predetermined width in a circumferential direction, and be offset radially inward from the outer peripheral surface of the stator.

[0013] The oil supply path may be formed in an axial direction, have a predetermined width in a circumferential direction, and be offset radially outward from the inner peripheral surface of the motor housing.

[0014] The oil spray path may include an inflow path circumferentially upwardly offset from a lower surface of the snap ring, a drain path extending radially inwardly through the snap ring from the other end of the inflow path, and a spray hole formed in a downstream end of the drain path.

[0015] The inflow path may be formed in a closed curve in a circumferential direction, or the one or more inflow paths may each have a predetermined width in the circumferential direction and be arranged to be spaced apart from each other in the circumferential direction.

[0016] The oil spray path may include a drain path offset upwardly from a radially inner bottom surface of the snap ring and a spray hole formed in a radially inner end of the drain path.

[0017] The plurality of drainage paths may have an equal spacing in a circumferential direction or a variable spacing based on a region of the stator where heat is generated.

[0018] The outflow path may have an upstream end in fluid communication with the inflow path, have a predetermined width in a circumferential direction, and be offset upwardly from the bottom of the snap ring.

[0019] The drainage path may have a longer offset length towards its radial inner side.

[0020] The drainage path may have a smaller circumferential width towards its radial inner side.

[0021] Further features and aspects will become apparent from the following detailed description, drawings and claims. Short description of the drawings Fig. 1 is a view showing the inside of a drive motor using a spray cooling method. Fig. 2 is a partial perspective cross-sectional view of a drive motor having a drive motor cooling mechanism according to an embodiment of the present disclosure. Fig. 3 is a partially enlarged perspective view showing a snap ring according to an embodiment of the present disclosure. Fig. 4 is a partially enlarged perspective view showing a cooling mechanism for a drive motor according to a first embodiment of the present disclosure. Fig. 5 is a partially enlarged perspective view showing an oil path of the snap ring according to the first embodiment of the present disclosure. Fig. 6 is a partially enlarged perspective view showing an oil supply path according to a second embodiment of the present disclosure. Fig. 7 is a partially enlarged perspective cross-sectional view showing an oil path of the snap ring according to the second embodiment of the present disclosure. Fig. 8 is a partially enlarged perspective view showing the oil flow path of the snap ring according to the second embodiment of the present disclosure. Fig. 9 is a partially enlarged perspective view showing the snap ring and a stator according to the second embodiment of the present disclosure. Fig. 10 is a partially enlarged perspective cross-sectional view showing an oil path of the snap ring according to a third embodiment of the present disclosure. Fig. 11 is a partially enlarged perspective view showing the oil path of the snap ring according to the third embodiment of the present disclosure. Detailed description of the embodiments

[0022] Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings.

[0023] Fig. 2 shows a partial perspective cross-sectional view of a drive motor with a cooling mechanism for a drive motor according to an embodiment of the present disclosure. Fig. 3 is a partially enlarged perspective view of a snap ring 300 according to an embodiment of the present disclosure.

[0024] As shown in the drawings, a cooling mechanism 1000 for a drive motor may include a cylindrical stator 100 wound with a coil, a cylindrical motor housing 200 that houses the stator 100, the snap ring 300 fitted into an upper inner surface of the motor housing 200 to secure an upper side of the stator 100 housed in the motor housing 200, and an oil supply device for supplying oil to the snap ring 300, although not shown in the drawings. The oil supply device may be, for example, an oil pump for circulating the oil. Therefore, the oil pumped by the oil pump can flow through a gap between the stator 100 and the motor housing 200 along a path formed in the motor housing 200 and supply the oil to the snap ring 300.

[0025] The cylindrical motor housing 200 may have a sealed bottom and an open top.

[0026] The cylindrical stator 100 having a predetermined thickness may have a coil wound on an inner peripheral surface and apply a current to the coil so as to rotate a rotor (not shown) arranged on an inner side of the stator 100.

[0027] The snap ring 300 may be formed in a ring shape with a predetermined width in a radial direction. The snap ring 300 may have a radially inner side protruding inward from an inner peripheral surface of the motor housing 200, while its radially outer periphery is fitted into a snap ring retaining groove 210 radially offset outward from the inner peripheral surface of a top surface of the motor housing 200. Furthermore, the snap ring 300 may have a radially inner lower surface protruding and in contact with a periphery of a top surface of the stator 100. Therefore, the stator 100 can be secured to the motor housing 200 by limiting upward movement of the stator 100 while the stator 100 is seated on the motor housing 200.

[0028] Here, the snap ring 300 may include an oil spray path 310 formed therein so as to receive the oil supplied to an oil supply path 400 formed between an outer peripheral surface of the stator 100 and the inner peripheral surface of the motor housing 200 to spray the oil onto a coil end part 110 on the top side of the stator 100.

[0029] The cooling mechanism 1000 having the above configuration will be described in detail with reference to the drawings.

[0030] Fig. 4 shows a partially enlarged perspective view of the cooling mechanism 1000 for a drive motor according to a first embodiment of the present disclosure, and Fig. 5 shows a partially enlarged perspective view of the oil spray path 310 of the snap ring according to the first embodiment of the present disclosure.

[0031] As shown in the drawings, the oil supply path 400 may be formed between the inner peripheral surface of the motor housing 200 and the outer peripheral surface of the stator 100. The oil supply path 400 may have a predetermined width in a circumferential direction and be offset radially inward from the outer peripheral surface of the stator 100. Although not shown in the drawings, in another embodiment, the oil supply path may be offset radially outward from the inner peripheral surface of the motor housing 200.

[0032] Here, an upper end of the oil supply path 400 may be in contact with the lower surface of the snap ring 300, and the oil spray path 310 may include an inflow path 311 offset upward in the circumferential direction from the lower surface of the snap ring 300 and an outflow path 312 extending radially inward through the snap ring 300 from a downstream end of the inflow path 311, i.e., the upper end. An upstream side of the inflow path 311 may communicate with the oil supply path 400 and distribute the oil supplied from the oil supply path 400 in the circumferential direction of the snap ring 300. The plurality of outflow paths 312 may be arranged to be spaced apart from each other in the circumferential direction of the snap ring 300, and may have a spray hole 315 formed in a downstream end to evenly spray the oil supplied through the inflow path 311 onto the coil end part 110 on the top side of the stator 100.

[0033] The drainage paths 312 may be spaced apart from each other while being equally spaced, or may be arranged more densely in an area where relatively large amounts of heat are generated, if necessary.

[0034] With the above configuration, the oil can be sprayed evenly onto the coil end portion 110 on the top side of the stator 100 or intensively onto a specific area of the coil end portion 110 by using only the snap ring 300 without a separate oil guide.

[0035] Fig. 6 shows a partially enlarged perspective view of an oil supply path 410 according to a second embodiment of the present disclosure. Fig. 7 is a partially enlarged perspective cross-sectional view of an oil spray path 320 of the snap ring 300 according to the second embodiment of the present disclosure and shows Fig. 8 is a partially enlarged perspective view of the oil spray path 320 of the snap ring 300 according to the second embodiment of the present disclosure. Fig. 9 is a partially enlarged perspective view of the stator 100 and the snap ring 300 according to the second embodiment of the present disclosure.

[0036] With reference to Fig. 6, the plurality of oil supply paths 410 may be formed in a vertical longitudinal direction, offset inward from the outer peripheral surface of the stator 100, and arranged to be spaced apart from each other in the circumferential direction. As shown in the drawings, the plurality of oil supply paths 410 may have a closer spacing, particularly in a region where relatively high heat generation occurs.

[0037] In addition, the oil spray path 320 may be configured with reference to the Fig. 7 to 9 include an inflow path 321 that is offset upward in the circumferential direction from the lower surface of the snap ring 300, and an outflow path 322 that extends radially inward through the snap ring 300 from a downstream end of the inflow path 321, i.e., the upper end. The outflow path 322, which is arranged on the densely arranged plurality of oil supply paths 410, may have the following configuration to increase a spray flow rate and a spray distance. The outflow path 322 may have an upstream end fluidly connected to the inflow path 321, may have a predetermined width in the circumferential direction, and may be offset upward from the lower surface of the snap ring 300. Specifically, the outflow path 322 may have a longer offset length toward its radially inner side, i.e., its downstream side.That is, the drainage path 322 may have an increased vertical width toward its downstream side. Therefore, a large amount of oil supplied from the oil supply path 410 can be evenly sprayed because a spray hole 325 formed in a downstream end of the drainage path 322 has an enlarged area. Furthermore, the top of the drainage path 322 may be inclined upward toward its downstream side to increase the spray distance.

[0038] Fig. 10 shows a partially enlarged perspective cross-sectional view of an oil spray path 330 of the snap ring 300 according to a third embodiment of the present disclosure, and Fig. 11 shows a partially enlarged perspective view of the oil spray path 330 of the snap ring 300 according to the third embodiment of the present disclosure.

[0039] However, the oil spray path 330 according to the second embodiment described above can have a reduced oil flow rate because the path has an increased cross-sectional area toward its downstream side. To solve this problem, the oil spray path 330 of the snap ring 300 according to the third embodiment can be configured as follows.

[0040] The oil spray path 330 may include a drain path 332 that is in fluid communication with the oil supply path 410. The drain path 332, which is arranged on the densely arranged plurality of oil supply paths 410, may have the following configuration to maintain an oil spray velocity while increasing the spray flow rate and spray distance.

[0041] The drainage path 332 may be formed on the radially inner side of the snap ring 300 and offset upward from the lower surface of the snap ring 300. Furthermore, the drainage path 332 may have a longer recessed length toward its radially inner side, that is, its downstream side. Furthermore, the drainage path 322 may have a smaller circumferential width toward its downstream side. Therefore, the oil spray path 330 may receive the oil directly from the oil supply path 410 to the drainage path 332 and maintain a cross-sectional area of the drainage path 322 to thereby maintain or increase the oil spray velocity. Furthermore, the drainage path 322 may have a width that is again increased near a spray hole 335 to thereby increase an oil spray area.

[0042] The cooling mechanism for a drive motor according to the present disclosure configured as above can reduce the manufacturing cost or process cost for forming the cooling mechanism by spraying the cooling oil onto the stator using the snap ring for fixing the stator to the motor housing, without requiring a separate configuration for spraying the oil onto the stator.

[0043] The cooling mechanism for a drive motor according to the present disclosure can be applied to engines of various specifications that require intensive cooling at a specific location at a low cost because the spray location of the cooling oil or a supply flow rate can be easily adjusted by changing a design of the snap ring.

[0044] The spirit of the present disclosure should not be limited to the embodiment described above. The present disclosure can be applied to various fields and modified in various ways by those skilled in the art without departing from the scope of the present disclosure as claimed in the claims. Therefore, it is obvious to those skilled in the art that these changes and modifications fall within the scope of the present disclosure.

Claims

[1] Cooling mechanism for a drive motor, the mechanism comprising: a cylindrical stator wound with a coil and comprising a first and a second side; a cylindrical motor housing having a sealed first side and an open second side and receiving the stator therein; a snap ring fitted into an inner peripheral surface of the second side of the motor housing to have a radially inner side projecting inward from the inner peripheral surface of the motor housing, and securing the second side of the stator by having a surface projecting and in contact with a periphery of a surface of the stator; and an oil supply path formed between an outer peripheral surface of the stator and the inner peripheral surface of the motor housing for supplying oil to the snap ring through the oil supply path, wherein the snap ring includes an oil spray path having an upstream side in fluid communication with the oil supply path and a downstream side passing through an inner peripheral surface of the snap ring and exposed to the second side of the stator. [2] The mechanism according to claim 1, wherein the oil supply path is formed in an axial direction of the stator, has a predetermined width in a circumferential direction of the stator, and is offset radially inward from the outer peripheral surface of the stator. [3] The mechanism according to claim 1 or 2, wherein the oil supply path is formed in an axial direction of the stator, has a predetermined width in a circumferential direction of the stator, and is offset radially outward from the inner peripheral surface of the motor housing. [4] A mechanism according to any one of claims 1 to 3, wherein the oil spray path comprises: an inflow path offset upwardly from a lower surface of the snap ring and including a first and a second end, an outflow path extending radially inwardly from the second end of the inflow path through the snap ring, and a spray hole formed in a downstream end of the drainage path. [5] The mechanism according to claim 4, wherein the inflow path is formed in a closed curve in a circumferential direction of the stator. [6] Mechanism according to claim 4 or 5, where the inflow path is present multiple times and wherein the plurality of inflow paths each have a predetermined width in the circumferential direction and are arranged to be spaced apart from each other in the circumferential direction. [7] Mechanism according to one of claims 4 to 6, where the drainage path is present multiple times and wherein the plurality of drainage paths have an equal pitch in a circumferential direction of the stator or have a variable pitch based on a region of the stator in which heat is generated. [8] The mechanism according to any one of claims 4 to 7, wherein the outflow path has an upstream end in fluid communication with the inflow path, has a predetermined width in a circumferential direction of the stator, and is offset upwardly from the lower surface of the snap ring. [9] The mechanism of claim 8, wherein the drainage path has a longer recessed length toward a radially inner side of the snap ring. [10] The mechanism of claim 9, wherein the drainage path has a smaller circumferential width toward a radially inner side of the snap ring. [11] A mechanism according to claim 9 or 10, wherein the drainage path has an increased width near the spray hole. [12] A mechanism according to any one of claims 1 to 11, wherein the oil spray path comprises: a drainage path offset upwardly from a radially inner lower surface of the snap ring, and a spray hole formed in a radially inner end of the drainage path. [13] The mechanism according to claim 12, wherein the oil spray path includes an upward inclination toward its downstream side so as to increase a spray distance. [14] Mechanism according to claim 12 or 13, where the drainage path is present multiple times and wherein the plurality of drainage paths have an equal pitch in a circumferential direction of the stator or have a variable pitch based on a region of the stator in which heat is generated.

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