Cooling mechanism, cooling unit, and motor unit

Abstract

A cooling mechanism (4A) wherein the bottom wall (44) slopes downward from the portion (47) directly below the inlet (45) toward the first side wall (48), and the internal space of the chamber (42) is formed such that, when viewed along the length direction (L) of the chamber (42), the first region (R1) between the first side wall (48) and the inlet (45) is wider than the second region (R2) between the second side wall (49) and the inlet (45).

Description

[0001] Cross-references to related applications

[0002] This application is based on Japanese Patent Application No. 2025-066267, filed on April 14, 2025, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to a cooling mechanism, a cooling unit, and a motor unit for cooling the coil ends of a coil mounted on a stator core. Background Technology

[0004] In recent years, with the popularization of electric vehicles, there has been a demand for motor miniaturization from the perspectives of increasing the freedom of vehicle layout, reducing the number of components, and lowering costs. To miniaturize motors without reducing output, it is necessary to increase the motor's output density. One method for this is to increase the current density of the coils mounted on the stator. However, increasing the coil current density increases the Joule heat generated by the coils, making coil cooling technology crucial for maintaining motor performance. For example, JP2024-078234A discloses a cooling mechanism that can inject refrigerant from above onto the coil ends.

[0005] However, when the motor rotor rotates, it inevitably generates wind (rotational wind). In the aforementioned prior art, the refrigerant is blown away by the rotor's rotational wind, which may prevent it from covering the coil ends as intended. To reliably cover the coil ends with refrigerant, a technique to increase the refrigerant injection output (injection speed) is desired. Summary of the Invention

[0006] The present invention was made in view of the above circumstances, and its object is to provide a cooling mechanism, a cooling unit, and a motor unit capable of increasing the injection velocity of refrigerant injected to the end of a coil.

[0007] To achieve the above objectives, the cooling mechanism of the present invention is configured as follows. The cooling mechanism of the present invention discharges refrigerant to a portion of a coil mounted on a stator core, specifically the end of the coil protruding axially from the stator core. The cooling mechanism includes: an inlet for introducing the refrigerant from the outside, an injection port for injecting the refrigerant, and a chamber communicating with the inlet and the injection port and extending horizontally. An inlet is provided on the top wall of the chamber, through which the refrigerant introduced by the inlet flows in, and an outlet is provided on the bottom wall of the chamber, through which the refrigerant flows out to the injection port. The bottom wall slopes downwards from the portion directly below the inlet toward a first sidewall located at one end in a width direction orthogonal to the length direction extending from the chamber, such that the refrigerant flowing down from the inlet flows toward one side of the chamber in the width direction. When viewed along the length of the chamber, the internal space of the chamber is formed such that a first region between the first sidewall and the inlet is wider than a second region between the second sidewall disposed at the other end of the width direction of the chamber and the inlet.

[0008] According to the above structure, firstly, in the cooling mechanism, an inlet is provided on the top wall of a chamber that communicates with an inlet for introducing refrigerant from the outside and an injection port for injecting refrigerant. Refrigerant introduced from the inlet flows into the chamber through this inlet, thereby allowing the refrigerant to flow down into the chamber from the inlet. On the other hand, an outlet is provided on the bottom wall of the chamber, through which the refrigerant flows out to the injection port, thereby allowing the refrigerant accumulated in the chamber to flow out from the outlet to the injection port, and then be injected from the injection port towards the end of the coil.

[0009] Furthermore, the bottom wall slopes downwards from the portion directly below the inlet toward the first sidewall located at one end in the width direction orthogonal to the length direction extending from the chamber (i.e., the second sidewall located away from the other end in the width direction of the chamber). This causes the refrigerant flowing down from the inlet to flow toward the width direction of the chamber. Consequently, compared to the second region located between the second sidewall and the inlet when viewed along the length direction, the refrigerant flowing down from the inlet is more likely to flow toward the first region located between the first sidewall and the inlet when viewed along the length direction. As a result, more refrigerant flows toward the first region than toward the second region. This promotes the concentration of refrigerant in the first region (...effect 1).

[0010] Furthermore, the internal space of the chamber is configured such that, when viewed along the length of the chamber, the first region is wider than the second region, thereby relatively reducing the resistance (pressure loss) in the first region. As a result, the refrigerant entering the first region flows more actively along the length direction compared to the refrigerant entering the second region. This promotes the flow of refrigerant along the length direction with the first region as the center (...effect 2).

[0011] Through the synergistic effect of actions 1 and 2 described above, the flow rate of refrigerant into the chamber increases. As a result, the refrigerant pressure (dynamic pressure) increases throughout the entire internal space of the chamber, and the refrigerant velocity delivered to the injection port increases. Therefore, the injection velocity of the refrigerant injected towards the coil end can be increased.

[0012] In the above-described cooling mechanism, the jet flow path connecting the outlet and the nozzle can be inclined downwards from the outlet to the nozzle toward the inner side of the axial direction.

[0013] However, when the motor rotor rotates, the inevitable rotor airflow typically vortexes around the axial direction, moving away from the rotor shaft (i.e., outwards). In this regard, according to the structure described above, the refrigerant is injected from the nozzle inwards towards the axial direction, in other words, in the opposite direction to the rotor airflow. This counteracts (eliminates) the effect of the rotor airflow on the refrigerant injection. Therefore, it allows for more reliable refrigerant coverage of the coil ends.

[0014] In the aforementioned cooling mechanism, the injection nozzle can be formed such that its front end narrows inward toward the axial direction. According to this structure, the sidewalls of the injection path are formed to converge toward the front end, thus the refrigerant is guided toward the front end along the shape of the sidewalls of the injection path, i.e., guided in the opposite direction to the rotational airflow of the rotor, while being injected from the injection nozzle. Therefore, it is possible to reliably cover the coil ends with refrigerant without significantly altering the overall shape of the cooling mechanism.

[0015] The cooling mechanism can extend along a transverse direction orthogonal to the axial and vertical directions to the full length of the top region of the coil end, such that when the coil end is viewed from directly above, the refrigerant can be seen covering the entire top region, and the chamber can extend from one end of the transverse direction of the cooling mechanism to the other end.

[0016] According to the above structure, firstly, the cooling mechanism extends along the entire length of the top region of the coil end in the transverse direction, thereby enabling the refrigerant to cover the coil end from one end of the top region to the other end. Here, the cooling mechanism extends in the transverse direction, and the coil end is arranged in a ring shape according to the shape of the stator core, so as it moves from the center (i.e., the topmost part) of the top region of the coil end towards both ends, the distance between the cooling mechanism and the coil end increases. Therefore, in order to reliably cover the coil ends at both ends of the top region with refrigerant, it is desirable to further increase the refrigerant injection velocity.

[0017] In this regard, the chamber extends from one end of the cooling mechanism in the transverse direction to the other end, that is, to approximately the entire length of the cooling mechanism. This ensures that the internal space of the chamber is as wide as approximately the entire length of the cooling mechanism, thus further increasing the flow rate of refrigerant flowing into the chamber. Consequently, the pressure of the refrigerant within the chamber is further increased, and the flow rate of the refrigerant delivered to the injection port is further increased, thus further increasing the injection velocity of the refrigerant injected towards the coil ends. Therefore, according to the above structure, the refrigerant can more reliably cover the coil ends at both ends of the top region.

[0018] In the aforementioned cooling mechanism, the chamber can be formed by enclosing a hollow, bottomless main body and a base plate component separate from the main body, and a jet flow path connecting the outlet and the injection port can be provided on the base plate component along the thickness direction of the base plate component. According to this structure, the jet flow path can be easily formed by stamping or other processes.

[0019] Furthermore, the cooling unit of the present invention includes the cooling mechanism, a supply section for supplying refrigerant to the inlet of the cooling mechanism, and a control section for controlling the supply section, wherein the control section causes the flow rate of the refrigerant supplied from the supply section to the inlet to be periodically varied. According to this structure, firstly, as described above, the injection velocity of the refrigerant injected into the coil end can be increased.

[0020] However, as a means of increasing the refrigerant coverage area at the coil end (refrigerant spray area), increasing the number of nozzles in the cooling mechanism is considered. However, as the number of nozzles increases, the spacing between adjacent nozzles, that is, the spacing between the liquid refrigerant columns ejected from these nozzles, narrows, thus potentially causing adjacent liquid columns to attract each other (the so-called Coanda effect). If the Coanda effect occurs, two adjacent liquid columns will converge into one liquid column, thus reducing the effectiveness of increasing the number of nozzles to expand the refrigerant spray area at the coil end.

[0021] Regarding this, according to the above structure, the refrigerant injected from the nozzle is given a fluctuating (pulsating) characteristic, thus causing a deviation in the direction of refrigerant travel within the chamber. Affected by this deviation, the direction of the refrigerant injected from each nozzle changes randomly, so even if two liquid columns injected from adjacent nozzles are close to each other, they can easily separate. Therefore, even when the number of nozzles is increased to expand the refrigerant spray area at the coil end, the Coanda phenomenon can be suppressed.

[0022] Furthermore, the motor unit of the present invention includes the cooling mechanism and a stator having the stator core on which the coil is mounted. According to this structure, similarly to the above, the injection velocity of the refrigerant injected to the ends of the coil can be increased.

[0023] As described above, according to the present invention, the injection velocity of the refrigerant injected into the coil end can be increased. Attached Figure Description

[0024] Figure 1 This is a schematic diagram illustrating a motor unit according to one embodiment of the present invention.

[0025] Figure 2 It means Figure 1 A partial sectional three-dimensional view of the internal structure of the motor unit.

[0026] Figure 3 This is an exploded perspective view of a cooling mechanism according to an embodiment of the present invention.

[0027] Figure 4 It is Figure 3 The schematic cross-sectional view of the cooling mechanism is shown below, cut along a plane orthogonal to the length direction.

[0028] Figure 5 It means Figure 3 A schematic diagram showing the positional relationship between the cooling mechanism and the end of the coil.

[0029] Figure 6 This is a diagram (1) used to illustrate the oil flow within the chamber.

[0030] Figure 7 This is a diagram (2) used to illustrate the oil flow within the chamber.

[0031] Figure 8 This is a diagram (3) used to illustrate the oil flow within the chamber.

[0032] Figure 9 This is a diagram used to illustrate the injection of oil from the rotating air of the cooling mechanism into the rotor.

[0033] Figure 10 This is a schematic diagram illustrating a modified example of an injection nozzle.

[0034] Figure 11 This is a diagram used to illustrate the Coanda phenomenon.

[0035] Figure 12 This is a chart showing an example of how the oil pump's supply changes over time. Detailed Implementation

[0036] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0037] Figure 1 This is a schematic diagram illustrating a motor unit A according to one embodiment of the present invention. Figure 1As shown, the motor unit A in this embodiment includes a motor 1 used as a drive source for vehicles such as electric vehicles and hybrid vehicles. The motor 1 is, for example, an interior permanent magnet motor (IPM motor).

[0038] like Figure 1 As shown, motor 1 is a so-called radial clearance type motor, including a cylindrical rotor 11 with a shaft 10 fixed in a central hole, and a stator 12 arranged around the outer peripheral surface of the rotor 11.

[0039] The rotor 11 is composed of multiple layers of electromagnetic steel plates (e.g., silicon steel plates). Permanent magnets (not shown) are embedded in the rotor 11.

[0040] Figure 2 This is a partially sectional perspective view showing the internal structure of motor unit A. Figure 2 For ease of understanding, the section lines at the cross-section have been omitted. For example... Figure 2 As shown, the stator 12 has a cylindrical stator core 13 and coils 2. The stator core 13 includes a cylindrical yoke 14 and a plurality of teeth 15, which protrude radially inward from the inner circumferential surface of the yoke 14 and are arranged at equal intervals along the circumferential direction. A groove 16 is formed between adjacent teeth 15, extending along the axial direction δ of the stator core 13. Thus, a plurality of grooves 16, which are also arranged at equal intervals along the circumferential direction, are formed on the inner circumference of the stator core 13, similar to the plurality of teeth 15.

[0041] Coil 2 is a so-called SC (segmented conductor) winding composed of multiple interconnected segmented coils. Coil 2 is mounted on the stator core 13 by insertion into slot 16, including coil end 20 protruding axially δ from the stator core 13. Coil 2 is the main heat source of the stator 12.

[0042] return Figure 1 In addition to the motor 1, the motor unit A also includes a housing 3. The housing 3 is box-shaped with a bottom 30, and houses the rotor 11 and the stator 12. Bearings 31 and 32, which rotatably support the shaft 10, are mounted at both ends of the housing 3 along the axial direction δ. The housing 3 is made of a non-magnetic material (e.g., aluminum).

[0043] The motor unit A described above is connected to a circulation path CR through which refrigerant (e.g., oil) circulates. The circulation path CR is sequentially connected to the motor unit A, an oil pump P (supply unit) for circulating oil, and an oil cooler C for cooling the oil. When the oil pump P is driven, the oil accumulated at the bottom 30 of the housing 3 is transported to the oil cooler C, and the oil cooled by the oil cooler C is supplied to the upper part of the housing 3 of the motor unit A. In other words, the oil pump P supplies oil to the motor unit A. The oil supplied to the motor unit A cools the motor 1 by drawing heat from it, and then returns to the bottom 30 of the housing 3. The flow rate (discharge rate) of the oil pump P is controlled by the control unit CU that controls the oil pump P.

[0044] like Figure 1 and Figure 2 As shown, in addition to the above-described structure, motor unit A also includes cooling mechanisms 4A and 4B that discharge oil to the coil end 20. By using cooling mechanisms 4A and 4B to spray oil (in a spraying manner) onto the coil end 20, which is the main heat source of the stator 12, the stator 12 can be effectively cooled.

[0045] Cooling mechanisms 4A and 4B are disposed at both ends of the axial direction δ on the upper part of the housing 3. When inserted from above into the openings 34 formed in the top plate portion 33 of the housing 3, cooling mechanisms 4A and 4B are secured by fastening members 35 (see reference 35). Figure 2 It is fixed to the top plate 33 of the housing 3. The cooling mechanisms 4A and 4B have a common structure, so the cooling mechanism 4A will be described below as representative of them.

[0046] Figure 3 This is an exploded perspective view of a cooling mechanism 4A according to an embodiment of the present invention. Figure 4 This is a schematic cross-sectional view showing the cooling mechanism 4A cut along a plane orthogonal to the length direction L. Figure 5 This is a schematic diagram showing the positional relationship between the cooling mechanism 4A and the coil end 20. (For example...) Figure 3 and Figure 4 As shown, the cooling mechanism 4A is hollow, and a chamber 42 extending horizontally is provided inside it. The width direction W of the chamber 42 is orthogonal to the length direction L of the chamber 42. In this embodiment, the cooling mechanism 4A is configured such that the width direction W is consistent with the axial direction δ.

[0047] like Figure 5 As shown, in this embodiment, the cooling mechanism 4A extends along the transverse direction T, which is orthogonal to the axial direction δ and the vertical direction V, to the full length of the top region 23, such that when the coil end 20 is viewed from directly above, the oil covers the entire top region 23 of the coil end 20. The chamber 42 extends from one end 40 of the cooling mechanism 4A in the transverse direction T to the other end 41, in other words, to approximately the full length of the cooling mechanism 4A.

[0048] return Figure 4 An external circulation passage CR (see reference) is provided on the upper part of the cooling mechanism 4A. Figure 1 An oil inlet IP is provided at the bottom of the cooling mechanism 4A, and an oil injection port OP is provided at the bottom of the cooling mechanism 4A. In this embodiment, the inlet IP opens upwards, and the injection port OP opens downwards. The chamber 42 is connected to the inlet IP and the injection port OP. An inlet 45 is provided on the top wall 43 of the chamber 42, through which oil introduced by the inlet IP flows in. An outlet 46 is provided on the bottom wall 44 of the chamber 42, through which oil flows out to the injection port OP.

[0049] like Figure 3 and Figure 4 As shown, the cooling mechanism 4A in this embodiment is composed of a hollow, bottomless main body 50 and a base plate component 51 that is separate from the main body 50. That is, the chamber 42 in this embodiment is formed by the main body 50 and the base plate component 51 enclosing it. Figure 3 As shown, the base plate component 51 is fixed to the lower part of the main body 50 by multiple fastening components such as bolts (not shown). A sealing element (not shown) is provided between the main body 50 and the base plate component 51 to liquid-tightly seal the internal space of the chamber 42.

[0050] The main body 50 is formed, for example, of aluminum, iron, etc. The main body 50 includes a rectangular top plate portion 52 and a peripheral plate portion 53 extending downward from the entire periphery of the top plate portion 52. Figure 3 As shown, a pair of side plate portions 54 and 55 extending along the length direction L in the peripheral plate portion 53 are provided with fastening holes 56 for fastening fastening members (not shown). These fastening holes 56 are arranged in a row along the length direction L of the chamber 42. A portion of the inner surface of the side plate portion 55 (i.e., a portion of the inner peripheral wall of the chamber 42) protrudes towards the inside of the chamber 42 to form a boss portion 57 surrounding the fastening hole 56.

[0051] The base plate component 51 is formed, for example, by stamping an electromagnetic steel sheet. An insertion hole 58 and a jet flow path 59 are provided on the base plate component 51, extending through the thickness direction of the base plate component 51. A fastening member, which is fastened in a fastening hole 56 in the main body 50, is inserted into the insertion hole 58. The jet flow path 59 connects the outlet 46 to the jet port OP. Figure 4 As shown, in this embodiment, the base plate component 51 is fixed to the main body 50 with a downward tilt towards one side of the width direction W (outer side of the axial direction δ in this embodiment) when viewed along the length direction L. Accompanying this, the bottom wall 44 of the chamber 42 is tilted relative to the horizontal plane, and the jet flow path 59 is tilted downward from the outlet 46 to the jet port OP towards the inner side of the axial direction δ.

[0052] In the aforementioned cooling mechanism 4A, the oil pump P (refer to...) Figure 1 Oil supplied from the circulation passage CR to the inlet IP flows down from the inlet 45 into the chamber 42. Then, the oil accumulated in the chamber 42 flows out from the outlet 46 to the spray port OP, and is sprayed from the spray port OP towards the coil end 20. In order to increase the oil spray speed, the cooling mechanism 4A has the following shape features.

[0053] Figures 6-8 These are diagrams (1) to (3) used to illustrate the oil flow within the chamber. For example... Figure 4 and Figure 6 As shown, the bottom wall 44 of the chamber 42 slopes downward from the portion 47 directly below the inlet 45 toward the first sidewall 48 disposed at one end of the width direction W of the chamber 42 (i.e., away from the second sidewall 49 disposed at the other end of the width direction W of the chamber 42), so that the oil flowing down from the inlet 45 flows toward one side of the width direction W of the chamber 42 (towards the outer side of the axial direction δ in this embodiment).

[0054] Based on this shape characteristic, compared to the second region R2 (represented by sparse dots in the figure) located between the second sidewall 49 and the inlet 45 when viewed along the length direction L, the oil flowing down from the inlet 45 is more likely to flow to the first region R1 (represented by dense dots in the figure) located between the first sidewall 48 and the inlet 45 when viewed along the length direction L. As a result, as... Figure 6 As indicated by the middle arrow, more oil flows to the first region R1 than to the second region R2. This promotes the concentration of oil in the first region R1 (...effect 1).

[0055] In addition, such as Figure 4 and Figure 6 As shown, the internal space of chamber 42 is formed such that, when viewed along the length direction L of chamber 42, the first region R1 is wider than the second region R2. Specifically, the internal space of chamber 42 is formed such that, at any cross-section orthogonal to the length direction L, the cross-sectional area of ​​the first region R1 is greater than the cross-sectional area of ​​the second region R2.

[0056] Based on this shape characteristic, the resistance (pressure loss) in the first region R1 is relatively lower (compared to the second region R2). As a result, as... Figure 7 As indicated by the middle arrow, the oil entering the first region R1 flows more actively along the length direction L compared to the oil entering the second region R2. This promotes the oil flow along the length direction L centered on the first region R1 (...effect 2).

[0057] Through the synergistic effect of actions 1 and 2 described above, the flow rate of oil into chamber 42 increases. As a result, the oil pressure (dynamic pressure) increases throughout the entire internal space of chamber 42 and is delivered to the injection port OP (refer to...). Figure 4 and Figure 6 The flow rate of oil to the coil end 20 (refer to) is increased. Therefore, it is possible to increase the flow rate of oil to the coil end 20 (refer to) Figure 1 and Figure 2 The injection speed of the injected oil.

[0058] By forming an oil flow centered on the first region R1 within the chamber 42 as described above, such as Figure 8 As indicated by the thick solid arrow, oil flowing in both directions L from the first region R1 enters the second region R2, and as indicated by the thin solid arrow, oil from the second region R2 enters the first region R1, resulting in the formation of an oil vortex. Thus, the oil is evenly distributed throughout the entire interior space of the chamber 42, allowing oil to be evenly sprayed from each injection port OP towards the coil end 20.

[0059] Figure 9 This diagram illustrates the injection of oil from the rotating airflow into the rotor 11 via the cooling mechanism 4A. Figure 9 In the diagram, an arrow schematically indicates oil injection from the injection port OP of the cooling mechanism 4A. However, when the rotor 11 of the motor 1 rotates, through this rotation, as... Figure 9 As indicated by the hollow arrow, wind (rotating wind) is inevitably generated. Typically, the rotating wind from rotor 11 vortexes around axis δ (i.e., towards the outside of axis δ) away from rotor 11. At low oil injection speeds, the oil may be blown away by the rotating wind from rotor 11, failing to cover the coil end 20 as intended. Regarding this, as stated above, by increasing the injection speed of the oil towards the coil end 20, the oil can be made to cover the coil end 20 as intended.

[0060] Furthermore, as described above, the jet flow path 59 slopes downwards from the outlet 46 to the jet port OP towards the inner side of the axial direction δ (see reference). Figure 4 and Figure 6 This causes the oil to be sprayed from the injection port OP toward the inner side of the axial direction δ, in other words, toward the direction opposite to the direction of the rotating airflow of the rotor 11. Therefore, the effect of the rotating airflow of the rotor 11 on the oil spray can be counteracted (eliminated). As a result, the oil can be more reliably covered at the coil end 20.

[0061] Figure 10This is a schematic diagram illustrating a modified example of the injection port OP. However, regarding the formation of the injection flow path 59, it is easier technically to form the injection flow path 59 perpendicular to the bottom wall 44 of the chamber 42, and therefore preferred. If the injection flow path 59 is formed perpendicular to the bottom wall 44, in order to reliably cover the coil end 20 with oil, it is considered to make the injection flow path 59 more inclined, so that the injection port OP is further biased towards the inner side of the axial direction δ. However, to achieve this, the bottom wall 44 needs to be further inclined relative to the horizontal plane. However, the more inclined the bottom wall 44 is relative to the horizontal plane, the closer the distance between the cooling mechanism 4A and the coil 2 becomes. From the viewpoint of ensuring the insulation distance between the cooling mechanism 4A and the coil 2, the inclination angle of the bottom wall 44 is limited.

[0062] Regarding this point, as mentioned above, when the jet flow path 59 slopes downwards and inwards towards the axial direction δ from the outlet 46 to the jet port OP, such as Figure 10 As shown, by forming the injection port OP to narrow inwards towards the axial direction δ, the tilt angle of the bottom wall 44 can be suppressed, and the oil can more reliably cover the coil end 20. According to this injection port OP, the sidewall of the injection flow path 59 is formed to converge towards the front end, so that the oil is guided towards the front end along the shape of the sidewall of the injection flow path 59, that is, guided in the opposite direction to the wind direction of the rotating airflow of the rotor 11, while being injected from the injection port OP. Therefore, the oil can more reliably cover the coil end 20 without significantly altering the overall shape of the cooling mechanism 4A.

[0063] Additionally, as described above, the cooling mechanism 4A extends along the transverse direction T to the entire length of the top region 23 of the coil end 20 (refer to...). Figure 5 This allows oil to be distributed from one end of the top region 23, at the coil end 21, to the other end, at the coil end 22. Here, the cooling mechanism 4A extends in the transverse direction T, and the coil ends 20 are arranged in an annular shape according to the shape of the stator core 13. Therefore, as the cooling mechanism 4A moves from the center (i.e., the very top) of the top region 23 towards both ends of the coil ends 20, the distance between the cooling mechanism 4A and the coil ends 20 increases. Therefore, in order to reliably cover the coil ends 21 and 22 at both ends of the top region 23 with oil, it is desirable to further increase the oil injection speed.

[0064] Regarding this, as mentioned above, chamber 42 extends to approximately the entire length of cooling mechanism 4A (see reference). Figure 5This ensures that the internal space of chamber 42 is approximately the entire length of the cooling mechanism 4A, thus further increasing the flow rate of oil into chamber 42. Consequently, the oil pressure within chamber 42 is further increased, and the flow rate of the oil delivered to the injection port OP is further increased, thus further increasing the injection speed of the oil injected into the coil ends 20. Therefore, according to the above structure, oil can more reliably cover the coil ends 21, 22 at both ends of the top region 23.

[0065] Furthermore, as described above, the base plate component 51 of the cooling mechanism 4A is separate from the main body 50, and the jet flow path 59 is configured to extend through the thickness direction of the base plate component 51 (see reference). Figure 4 and Figure 6 Thus, the jet flow path 59 can be easily formed through stamping and other processes.

[0066] It should be noted that, not limited to the above-described form, the main body 50 and the base plate component 51 of the cooling mechanism 4A can also be integrally formed. In addition, the shape of the chamber 42 of the cooling mechanism 4A is as described above. As long as the oil covers the coil end 20, there are no restrictions on the opening direction of the inlet IP and the spray port OP, the extension direction of the spray flow path 59, etc.

[0067] Figure 11 This is a diagram used to illustrate the Coanda phenomenon. Figure 12 This is a graph illustrating the time-dependent variation in the supply quantity of oil pump P. The cooling mechanisms 4A and 4B described above, along with oil pump P and control unit CU (all refer to...), Figure 1 Together they form a cooling unit.

[0068] However, as a means of increasing the coverage area (oil spray area) of oil on the coil end 20, increasing the number of spray nozzles OP of the cooling mechanism 4A is considered. However, as the number of spray nozzles OP increases, the spacing between adjacent spray nozzles OP, that is, the spacing between the oil columns sprayed from these spray nozzles OP, becomes narrower, therefore... Figure 11 As shown, it is possible for adjacent oil columns OC1 and OC2 to attract each other (the so-called Coanda phenomenon). Figure 11 In the diagram, dashed lines represent oil columns OC1 and OC2 when they do not attract each other. If the Coanda phenomenon occurs, the two adjacent oil columns OC1 and OC2 will converge into a single oil column OC, thus reducing the effectiveness of increasing the number of nozzles OP to expand the oil spray area at the coil end 20.

[0069] To suppress this Coanda effect, the control unit CU in this embodiment periodically varies the flow rate (supply amount) of the oil supplied from the oil pump P to the inlet IP of the cooling mechanism 4A. Specifically, the control unit CU increases or decreases the supply amount of the oil pump P, causing the flow rate of the oil in the inlet IP to slow down or increase. For example, as... Figure 12 As shown, the control unit CU causes the oil supply of the oil pump P to increase or decrease in a sinusoidal wave pattern over time. This variation in the supply of oil pump P imparts fluctuations (pulsations) to the oil ejected from the injection port OP, thus creating a deviation in the direction of oil travel within the chamber 42. Affected by this deviation, the direction of oil ejected from each injection port OP changes randomly, making it easy for two oil jets ejected from adjacent injection ports OP to separate easily, even when they are close together. Therefore, even when the number of injection ports OP is increased to expand the oil spray area at the coil end 20, the Coanda phenomenon can be suppressed.

[0070] Furthermore, as described above, by varying the supply of oil pump P, the incidental effect of increasing the oil spray area of ​​the oil injected from each injection port OP can be obtained due to the change in the injection direction of the oil injected from the injection port OP.

[0071] Furthermore, the shorter the length of the injection path 59 connecting the outlet 46 of chamber 42 to the injection port OP, the more easily the injection direction of the oil injected from the injection port OP is affected by the direction of oil travel within chamber 42. Therefore, in cases where the direction of oil travel within chamber 42 deviates due to variations in the oil supply, as described above, it is preferable to appropriately shorten the length of the injection path 59. This increases the variation in the injection direction of the oil injected from the injection port OP caused by the deviation in the direction of oil travel within chamber 42, thus more effectively suppressing the Coanda phenomenon.

[0072] The above embodiments are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of the present invention is not limited to the above embodiments and examples, but is defined based on the description in the claims. Furthermore, any modifications or alterations falling within the equivalent scope of the claims are also within the scope of the present invention.

[0073] This disclosure has been described based on embodiments, but it should be understood that this disclosure is not limited to these embodiments and structures. This disclosure also includes various modifications and variations within the same scope. In addition, various combinations or forms, further including only one element therein, or other combinations or forms with more than one element or less, also fall within the scope and spirit of this disclosure.

Claims

1. A cooling mechanism that discharges refrigerant to a portion of a coil mounted on a stator core, specifically the end of the coil protruding axially from the stator core, wherein, The cooling mechanism includes: an inlet for introducing the refrigerant from the outside, an injection port for injecting the refrigerant, and a chamber that communicates with the inlet and the injection port and extends horizontally. An inlet is provided on the top wall of the chamber, through which the refrigerant introduced by the inlet flows in, and an outlet is provided on the bottom wall of the chamber, through which the refrigerant flows out to the injection port. The bottom wall slopes downward from the portion directly below the inlet toward a first sidewall located at one end in a width direction orthogonal to the length direction extending from the chamber, such that the refrigerant flowing down from the inlet flows toward one side of the chamber in that width direction. When viewed along the length of the chamber, the internal space of the chamber is formed such that a first region between the first sidewall and the inlet is wider than a second region between the second sidewall disposed at the other end of the width direction of the chamber and the inlet.

2. The cooling mechanism according to claim 1, wherein, The jet flow path connecting the outlet and the nozzle slopes downwards and inwards from the outlet to the nozzle along the axial direction.

3. The cooling mechanism according to claim 2, wherein, The injection nozzle is formed such that its front end narrows inward toward the axial direction.

4. The cooling mechanism according to claim 1, wherein, The cooling mechanism extends along a transverse direction orthogonal to the axial and vertical directions to the full length of the top region of the coil end, such that when viewed from directly above, the refrigerant can be seen covering the entire top region. The chamber extends from one end of the cooling mechanism in the transverse direction to the other end.

5. The cooling mechanism according to claim 1, wherein, The chamber is formed by a hollow, bottomless main body and a base plate component that is separate from the main body. A jet flow path is provided on the base plate component, extending through the thickness direction of the base plate component, to connect the outlet and the injection port.

6. A cooling unit, wherein, The cooling unit includes: The cooling mechanism as described in claim 1 The supply section that supplies the refrigerant to the inlet of the cooling mechanism, and A control unit that controls the supply unit. The control unit causes the flow rate of the refrigerant supplied by the supply unit to the inlet to vary periodically.

7. A motor unit, wherein, The motor unit includes: the cooling mechanism of claim 1, and a stator having the stator core on which the coil is mounted.

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