Cooling mechanism, cooling unit and motor unit

Abstract

A cooling mechanism, a cooling unit, and a motor unit are provided that can increase the injection speed of a coolant. [Solution] A cooling mechanism 4A that discharges refrigerant toward the coil end, wherein the ceiling wall 43 of the chamber 42 is provided with an inlet 45 through which the refrigerant introduced through the inlet IP flows in, while the bottom wall 44 of the chamber 42 is provided with an outlet 46 through which the refrigerant flows out to the injection port OP, the bottom wall 44 slopes downward from a portion 47 directly below the inlet 45 toward a first side wall 48 located at one end of the width direction W of the chamber 42 so that the refrigerant flowing down from the inlet 45 flows in one direction in the width direction W of the chamber 42, and the internal space of the chamber 42 is formed so that, when viewed in the longitudinal direction L of the chamber 42, a first region R1 between the first side wall 48 and the inlet 45 is wider than a second region R2 between the inlet 45 and a second side wall 49 located at the other end of the width direction W of the chamber 42.

Description

[Technical Field]

[0001] The present invention relates to a cooling mechanism, a cooling unit, and a motor unit that cool the coil ends of a coil attached to a stator core. [Background technology]

[0002] With the recent spread of electric vehicles, there is a demand for smaller motors to improve vehicle layout flexibility and reduce the number of parts and costs. To reduce the size of a motor without reducing its output, it is necessary to increase the motor's output density, and one way to achieve this is to increase the current density of the coil attached to the stator. Increasing the coil's current density increases the amount of Joule heat generated in the coil, making it essential to have technology to cool the coil in order to maintain motor performance. For example, Patent Document 1 discloses a cooling mechanism capable of injecting refrigerant onto the coil ends from above. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2024-078234 Summary of the Invention [Problem to be solved by the invention]

[0004] When the rotor of a motor rotates, wind (rotational wind) is inevitably generated by this rotation. In the above-mentioned conventional technology, there is a risk that the refrigerant will be blown away by the wind caused by the rotor's rotation, and will not be applied to the coil ends as intended. There has been a demand for technology to increase the power (injection speed) at which the refrigerant is sprayed to ensure that it is applied to the coil ends.

[0005] The present invention has been made in view of the above, and has an object to provide a cooling mechanism, a cooling unit, and a motor unit that can increase the injection speed of the coolant injected toward the coil end. [Means for solving the problem]

[0006] In order to achieve the above object, a cooling mechanism according to the present invention is configured as follows. The cooling mechanism according to the present invention is a cooling mechanism that discharges a coolant toward a coil end that is part of a coil attached to a stator core and protrudes axially from the stator core. The cooling mechanism includes an inlet through which the coolant is introduced from the outside, an outlet through which the coolant is sprayed, and a horizontally extending chamber that communicates with the inlet and the outlet. An inlet is provided in the ceiling wall of the chamber through which the coolant introduced through the inlet flows, while an outlet is provided in the bottom wall of the chamber through which the coolant flows out to the outlet. The bottom wall slopes downward from a portion directly below the inlet toward a first side wall located at one end of the chamber in the width direction, so that the coolant flowing down from the inlet flows in one direction in the width direction perpendicular to the longitudinal direction of the chamber. The internal space of the chamber is formed such that, when viewed in the longitudinal direction of the chamber, a first region between the first side wall and the inlet is wider than a second region between the inlet and a second side wall located at the other end of the chamber in the width direction.

[0007] According to the above configuration, first, the cooling mechanism has an inlet for introducing a refrigerant from the outside and an inlet in the ceiling wall of the chamber, which communicates with the inlet and the outlet for injecting the refrigerant, so that the refrigerant can flow down from the inlet into the chamber. Meanwhile, the bottom wall of the chamber has an outlet through which the refrigerant flows out to the outlet, so that the refrigerant accumulated in the chamber can flow out from the outlet to the outlet and be sprayed from the outlet towards the coil end.

[0008] Furthermore, the bottom wall slopes downward from the portion directly below the inlet toward the first sidewall located at one end of the chamber in the width direction (i.e., away from the second sidewall located at the other end of the chamber in the width direction) so that the refrigerant flowing down from the inlet flows in one direction in the width direction perpendicular to the longitudinal direction of the chamber. This makes it easier for the refrigerant flowing down from the inlet to flow into the first region located between the first sidewall and the inlet in the length direction than to the second region located between the second sidewall and the inlet in the length direction. As a result, the amount of refrigerant flowing into the first region is greater than the amount of refrigerant flowing into the second region. This promotes the concentration of refrigerant in the first region (...Effect 1).

[0009] Furthermore, the internal space of the chamber is formed so that the first region is wider than the second region when viewed in the longitudinal direction of the chamber, thereby reducing the resistance (pressure loss) in the first region. As a result, the refrigerant that enters the first region flows more actively along the longitudinal direction than the refrigerant that enters the second region. This promotes the flow of the refrigerant along the longitudinal direction, centered around the first region (...Effect 2).

[0010] The combined effect of the above-mentioned effects 1 and 2 increases the flow rate of the refrigerant flowing into the chamber. As a result, the pressure (dynamic pressure) of the refrigerant increases throughout the entire interior space of the chamber, and the flow rate of the refrigerant sent to the injection port increases. This increases the injection speed of the refrigerant toward the coil end.

[0011] In the above cooling mechanism, an injection flow path connecting the outlet and the injection port may be inclined downward and inward in the axial direction from the outlet to the injection port.

[0012] When the rotor of a motor rotates, rotor rotational air inevitably occurs. Generally, the air swirls around the axial direction and moves away from the rotor (i.e., outward in the axial direction). In this regard, the above-described configuration ejects the refrigerant from the ejection port inward in the axial direction, in other words, in a direction opposite to the direction of the rotor rotational air. This offsets (cancels) the effect of the rotor rotational air on the refrigerant ejection. This ensures that the refrigerant is more reliably applied to the coil ends.

[0013] In the above cooling mechanism, the injection port may be formed so that its tip tapers inward in the axial direction. With this configuration, the side walls of the injection flow passage are formed so as to converge toward the tip, so that the refrigerant is injected from the injection port while being guided toward the tip along the shape of the side walls of the injection flow passage, i.e., in a direction against the wind direction of the rotor rotation. This allows the refrigerant to be more reliably applied to the coil ends without any particular changes to the overall shape of the cooling mechanism.

[0014] The cooling mechanism may extend in a transverse direction perpendicular to the axial direction and the vertical direction over the entire length of the top region of the coil end, which is visible when the coil end is viewed from directly above, so that the refrigerant is applied to the entire top region of the coil end, and the chamber may extend from one end of the cooling mechanism in the transverse direction to the other end.

[0015] According to the above configuration, first, the cooling mechanism extends transversely over the entire length of the top region of the coil ends, making it possible to spray the coolant thoroughly from one coil end to the other in the top region. However, because the cooling mechanism extends transversely and the coil ends are arranged in an annular shape following the shape of the stator core, the distance between the cooling mechanism and the coil ends increases from the center (i.e., the topmost part) of the top region of the coil ends toward both ends. Therefore, to ensure that the coolant is sprayed to both coil ends in the top region, it is desirable to further increase the coolant spray speed.

[0016] In this regard, by having the chamber extend from one transverse end to the other end of the cooling mechanism, in other words, over almost the entire length of the cooling mechanism, the chamber's internal space is secured to be wide over almost the entire length of the cooling mechanism, further increasing the flow rate of the coolant flowing into the chamber. This further increases the coolant pressure within the chamber and the flow rate of the coolant delivered to the injection port, thereby further increasing the injection speed of the coolant toward the coil ends. Therefore, with the above configuration, the coolant can be more reliably applied to both coil ends in the top region.

[0017] In the cooling mechanism described above, the chamber may be formed by being surrounded by a hollow, bottomless main body and a bottom plate member separate from the main body, and the bottom plate member may be provided with an injection flow path connecting the outlet and the injection port so as to penetrate the bottom plate member in a thickness direction of the bottom plate member. With this configuration, the injection flow path can be easily formed by punching or the like.

[0018] A cooling unit according to the present invention includes the cooling mechanism, a supply unit that supplies the refrigerant to the inlet of the cooling mechanism, and a control unit that controls the supply unit, and the control unit periodically varies the flow rate of the refrigerant supplied to the inlet by the supply unit. With this configuration, firstly, as described above, it is possible to increase the injection speed of the refrigerant injected toward the coil end.

[0019] One way to increase the area onto which the refrigerant is sprayed on the coil ends (the refrigerant spray area) is to increase the number of nozzles in the cooling mechanism. However, as the number of nozzles increases, the distance between adjacent nozzles, i.e., the distance between the liquid columns of refrigerant sprayed from these nozzles, becomes narrower, which can cause adjacent liquid columns to be attracted to each other (the so-called Coanda phenomenon). When the Coanda phenomenon occurs, two adjacent liquid columns merge into a single liquid column, reducing the effectiveness of increasing the number of nozzles to increase the refrigerant spray area on the coil ends.

[0020] In this regard, the above configuration imparts fluctuations (pulsations) to the refrigerant sprayed from the nozzles, causing variations in the direction of refrigerant flow within the chamber. This variation causes the direction of refrigerant sprayed from each nozzle to change randomly, making it easier for two liquid columns sprayed from adjacent nozzles to separate even when they approach each other. Therefore, the Coanda phenomenon can be suppressed even when the number of nozzles is increased to increase the refrigerant spray area on the coil end.

[0021] The motor unit according to the present invention includes the cooling mechanism and a stator having the stator core with the coils mounted thereon. With this configuration, the injection speed of the coolant toward the coil ends can be increased, as in the case described above. [Effects of the Invention]

[0022] As described above, according to the present invention, the injection speed of the refrigerant injected toward the coil end can be increased. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a schematic diagram showing a motor unit according to an embodiment of the present invention. [Figure 2] 2 is a partially cutaway perspective view showing the internal structure of the motor unit of FIG. 1. FIG. [Figure 3] FIG. 2 is an exploded perspective view of a cooling mechanism according to an embodiment of the present invention. [Figure 4] 4 is a schematic cross-sectional view showing the cooling mechanism of FIG. 3 cut along a plane perpendicular to the longitudinal direction. [Figure 5] 4 is a schematic diagram showing the positional relationship between the cooling mechanism and the coil end in FIG. 3. FIG. [Figure 6] FIG. 1 is a diagram (1) for explaining the flow of oil in the chamber. [Figure 7] FIG. 2 is a diagram (2) for explaining the flow of oil in the chamber. [Figure 8]FIG. 3 is a diagram for explaining the flow of oil in the chamber. [Figure 9] 10A and 10B are diagrams for explaining the spraying of oil from a cooling mechanism into the rotational wind of the rotor. [Figure 10] FIG. 10 is a schematic diagram showing an injection port according to a modified example. [Figure 11] FIG. 1 is a diagram for explaining the Coanda phenomenon. [Figure 12] 10 is a graph showing an example of fluctuations in the amount of oil supplied by an oil pump over time. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Fig. 1 is a schematic diagram showing a motor unit A according to one embodiment of the present invention. As shown in Fig. 1, 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).

[0025] As shown in FIG. 1, motor 1 is a so-called radial gap motor that includes a cylindrical rotor 11 with a shaft 10 fixed to a central hole, and a stator 12 arranged to surround the outer circumferential surface of rotor 11.

[0026] The rotor 11 is made by laminating a plurality of electromagnetic steel plates (for example, silicon steel plates) and has permanent magnets (not shown) embedded therein.

[0027] FIG. 2 is a partially cutaway perspective view showing the internal structure of motor unit A. Hatching in the cross section has been omitted in FIG. 2 for clarity. As shown in FIG. 2, stator 12 has a cylindrical stator core 13 and coils 2. Stator core 13 includes a cylindrical yoke 14 and a plurality of teeth 15 that protrude radially inward from the inner peripheral surface of yoke 14 and are arranged at equal intervals in the circumferential direction. Slots 16 are formed between adjacent teeth 15, penetrating stator core 13 in the axial direction δ. In this way, a plurality of slots 16 are provided in the inner peripheral portion of stator core 13 and are arranged at equal intervals in the circumferential direction, similar to the plurality of teeth 15.

[0028] The coil 2 is a so-called SC (segment conductor) winding consisting of multiple interconnected segment coils. The coil 2 is attached to the stator core 13 by being inserted into the slot 16, and includes coil ends 20 that protrude from the stator core 13 in the axial direction δ. The coil 2 is the main heat source of the stator 12.

[0029] Returning to FIG. 1, the motor unit A includes a housing 3 in addition to the motor 1. The housing 3 is formed in a box shape with a bottom 30, and houses a rotor 11 and a stator 12 inside. Bearings 31 and 32 that rotatably support the shaft 10 are attached to both ends of the housing 3 in the axial direction δ. The housing 3 is made of a non-magnetic material (e.g., aluminum).

[0030] The motor unit A described above is connected to a circulation path CR through which a refrigerant (e.g., oil) circulates. The circulation path CR is connected, in this order, to the motor unit A, an oil pump P (supply unit) that circulates the oil, and an oil cooler C that cools the oil. When the oil pump P is driven, the oil that has accumulated in the bottom 30 of the housing 3 is sent 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 removing heat from the motor 1, and then returns to the bottom 30 of the housing 3. The flow rate (discharge rate) of the oil pump P is controlled by a control unit CU that controls the oil pump P.

[0031] 1 and 2, in addition to the above configuration, motor unit A is equipped with cooling mechanisms 4A and 4B that discharge oil toward coil ends 20. By using cooling mechanisms 4A and 4B to spray (spray in a shower) oil onto coil ends 20, which are part of coil 2 and are the main heat source of stator 12, stator 12 can be efficiently cooled.

[0032] Cooling mechanisms 4A and 4B are arranged at both ends in the axial direction δ at the top of housing 3. Cooling mechanisms 4A and 4B are inserted from above into openings 34 formed in top plate portion 33 of housing 3, and are fixed to top plate portion 33 of housing 3 with fastening members 35 (see FIG. 2). Because cooling mechanisms 4A and 4B have a common configuration, the following description will focus on cooling mechanism 4A as a representative of them.

[0033] Fig. 3 is an exploded perspective view of a cooling mechanism 4A according to one embodiment of the present invention. Fig. 4 is a schematic cross-sectional view showing the cooling mechanism 4A cut along a plane perpendicular to the longitudinal direction L. Fig. 5 is a schematic diagram showing the positional relationship between the cooling mechanism 4A and the coil end 20. As shown in Figs. 3 and 4, the cooling mechanism 4A is formed hollow and has a chamber 42 extending in the horizontal direction provided therein. The width direction W of the chamber 42 is perpendicular to the longitudinal direction L in which the chamber 42 extends. The cooling mechanism 4A in this embodiment is arranged so that the width direction W is aligned with the axial direction δ.

[0034] As shown in FIG. 5, in this embodiment, the cooling mechanism 4A extends in a transverse direction T perpendicular to the axial direction δ and the up-down direction V over the entire length of the top region 23 of the coil end 20, which is visible when the coil end 20 is viewed from directly above, so that oil is applied to the entire top region 23 of the coil end 20, and the chamber 42 extends from one end 40 to the other end 41 of the cooling mechanism 4A in the transverse direction T, in other words, over almost the entire length of the cooling mechanism 4A.

[0035] Returning to FIG. 4, an inlet IP is provided at the top of the cooling mechanism 4A for introducing oil from an external circulation path CR (see FIG. 1), and an outlet OP for injecting the oil is provided at the bottom of the cooling mechanism 4A. In this embodiment, the inlet IP opens upward, and the outlet OP opens downward. The chamber 42 is in communication with the inlet IP and the outlet OP. An inlet 45 is provided in the ceiling wall 43 of the chamber 42, through which the oil introduced at the inlet IP flows in, and an outlet 46 is provided in the bottom wall 44 of the chamber 42, through which the oil flows out to the outlet OP.

[0036] 3 and 4, the cooling mechanism 4A in this embodiment is formed by combining a hollow, bottomless main body 50 with a bottom plate member 51 that is separate from the main body 50. That is, the chamber 42 in this embodiment is formed by being surrounded by the main body 50 and the bottom plate member 51. As shown in FIG. 3, the bottom plate member 51 is fixed to the bottom of the main body 50 by a plurality of fastening members (not shown) such as bolts. A sealant (not shown) that liquid-tightly seals the internal space of the chamber 42 is provided between the main body 50 and the bottom plate member 51.

[0037] The main body 50 is made of, for example, aluminum or iron. 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. As shown in FIG. 3 , a pair of side plate portions 54, 55 of the peripheral plate portion 53 extending in the longitudinal direction L are provided on the lower surface thereof with fastening holes 56 aligned in a row along the longitudinal direction L of the chamber 42 for fastening fastening members (not shown). 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 relatively inwardly of the chamber 42 to form a boss portion 57 surrounding the fastening hole 56.

[0038] The bottom plate member 51 is formed by punching, for example, an electromagnetic steel plate. The bottom plate member 51 is provided with insertion holes 58 into which fastening members to be fastened to fastening holes 56 of the main body 50 are inserted, and an ejection flow path 59 connecting the outlet 46 and the ejection port OP, which penetrate the bottom plate member 51 in the plate thickness direction. As shown in Fig. 4, in this embodiment, the bottom plate member 51 is fixed to the main body 50 in an attitude in which it is inclined downward toward one side of the width direction W (in this embodiment, outward in the axial direction δ) when viewed in the longitudinal direction L. Accordingly, the bottom wall 44 of the chamber 42 is inclined with respect to the horizontal plane, and the ejection flow path 59 is inclined downward toward the inward side in the axial direction δ from the outlet 46 to the ejection port OP.

[0039] In the cooling mechanism 4A, oil is supplied from the circulation path CR to the inlet IP by the oil pump P (see FIG. 1) and flows down from the inlet 45 into the chamber 42. The oil that has accumulated in the chamber 42 then flows out from the outlet 46 to the outlet OP, from which it is sprayed towards the coil end 20. The cooling mechanism 4A has the following geometric features to increase the oil spray speed.

[0040] 6 to 8 are diagrams (1) to (3) illustrating the flow of oil within the chamber. As shown in Figures 4 and 6, bottom wall 44 of chamber 42 is inclined downward from portion 47 directly below inlet 45 toward first side wall 48 located at one end of chamber 42 in the width direction W (i.e., away from second side wall 49 located at the other end of chamber 42 in the width direction W) so that oil flowing down from inlet 45 flows in one direction in the width direction W of chamber 42 (in this embodiment, outward in the axial direction δ).

[0041] Due to this geometric feature, oil flowing down from the inlet 45 is more likely to flow to the first region R1 (shown by dark dots in the figure) located between the first side wall 48 and the inlet 45 when viewed in the longitudinal direction L than to the second region R2 (shown by light dots in the figure) located between the second side wall 49 and the inlet 45 when viewed in the longitudinal direction L. As a result, as conceptually shown by the arrows in Figure 6, the amount of oil flowing to the first region R1 is greater than the amount of oil flowing to the second region R2. This promotes the concentration of oil in the first region R1 (...action 1).

[0042] 4 and 6, the internal space of the chamber 42 is formed so that the first region R1 is larger than the second region R2 when viewed in the longitudinal direction L of the chamber 42. Specifically, the internal space of the chamber 42 is formed so that the cross-sectional area of ​​the first region R1 is larger than the cross-sectional area of ​​the second region R2 in any cross section perpendicular to the longitudinal direction L.

[0043] This geometric feature reduces the resistance (pressure loss) in the first region R1 relatively (compared to the second region R2). As a result, as conceptually shown by the arrows in Figure 7, the oil that has entered the first region R1 flows more actively along the longitudinal direction L than the oil that has entered the second region R2. This promotes the flow of oil along the longitudinal direction L, centered around the first region R1 (...action 2).

[0044] The combined effect of the above-described effects 1 and 2 increases the flow rate of oil flowing into chamber 42. As a result, the oil pressure (dynamic pressure) increases throughout the entire internal space of chamber 42, and the flow rate of oil delivered to the injection port OP (see FIGS. 4 and 6) increases. This increases the injection speed of oil injected toward coil end 20 (see FIGS. 1 and 2).

[0045] As explained above, when an oil flow centered on the first region R1 is formed within the chamber 42, the oil that has flowed to both ends in the longitudinal direction L within the first region R1 enters the second region R2, as conceptually shown by the thick solid arrows in Figure 8, and the oil within the second region R2 enters the first region R1, as conceptually shown by the thin solid arrows, resulting in the formation of an oil vortex. This allows the oil to be distributed evenly throughout the entire internal space of the chamber 42, allowing the oil to be sprayed uniformly from each injection port OP toward the coil end 20.

[0046] FIG. 9 is a diagram illustrating oil spray from the cooling mechanism 4A toward the rotational wind of the rotor 11. In FIG. 9, arrows conceptually indicate the oil spray from the nozzles OP of the cooling mechanism 4A. When the rotor 11 of the motor 1 rotates, this rotation inevitably generates wind (rotational wind), as conceptually indicated by the outline arrows in FIG. 9. Generally, the rotational wind of the rotor 11 swirls around the axial direction δ, moving away from the rotor 11 in the axial direction δ (i.e., outward from the axial direction δ). If the oil spray velocity is low, the oil may be blown away by the rotational wind of the rotor 11 and may not be applied to the coil ends 20 as intended. In response to this, increasing the oil spray velocity toward the coil ends 20 as described above allows the oil to be applied to the coil ends 20 as intended.

[0047] Furthermore, as described above, because the injection flow path 59 is inclined downward and inward in the axial direction δ from the outlet 46 to the injection port OP (see FIGS. 4 and 6), the oil is injected from the injection port OP inward in the axial direction δ, in other words, in a direction against the direction of the rotational wind of the rotor 11, which offsets (cancels) the effect of the rotational wind of the rotor 11 on the injection of oil. This allows the oil to be more reliably applied to the coil ends 20.

[0048] 10 is a schematic diagram showing an injection port OP according to one modification. Regarding the formation of the injection flow passage 59, it is preferable to form the injection flow passage 59 perpendicular to the bottom wall 44 of the chamber 42, as this is technologically easier to produce. If the injection flow passage 59 were formed perpendicular to the bottom wall 44, it would be possible to further tilt the injection flow passage 59 so that the injection port OP faces further inward in the axial direction δ in order to more reliably spray oil onto the coil end 20. However, to achieve this, the bottom wall 44 would need to be further tilted with respect to the horizontal plane. However, the more the bottom wall 44 is tilted with respect to the horizontal plane, the closer the distance between the cooling mechanism 4A and the coil 2 becomes. However, there is a limit to the angle at which the bottom wall 44 can be tilted in order to ensure an insulating distance between the cooling mechanism 4A and the coil 2.

[0049] In this regard, when the injection flow passage 59 is inclined downward inward in the axial direction δ from the outlet 46 to the injection port OP as described above, by forming the injection port OP so that its tip tapers inward in the axial direction δ as shown in Figure 10, it is possible to more reliably spray oil onto the coil ends 20 while reducing the angle of inclination of the bottom wall 44. With this injection port OP, the side walls of the injection flow passage 59 are formed to converge toward the tip, so that the oil is injected from the injection port OP while being guided along the shape of the side walls of the injection flow passage 59 toward the tip, that is, in a direction against the wind direction of the rotation of the rotor 11. This makes it possible to more reliably spray oil onto the coil ends 20 without any particular changes to the overall shape of the cooling mechanism 4A.

[0050] Furthermore, as described above, because the cooling mechanism 4A extends in the transverse direction T over the entire length of the top region 23 of the coil end 20 (see FIG. 5 ), it is possible to spray oil all over the top region 23, from the coil end 21 at one end to the coil end 22 at the other end. Here, because the cooling mechanism 4A extends in the transverse direction T and the coil ends 20 are arranged in an annular shape in accordance with the shape of the stator core 13, the distance between the cooling mechanism 4A and the coil end 20 increases from the center (i.e., the top) of the top region 23 of the coil end 20 toward both ends. For this reason, to ensure that the oil is sprayed over the coil ends 21, 22 at both ends of the top region 23, it is desirable to further increase the oil spray speed.

[0051] In this regard, as described above, by having chamber 42 extend over substantially the entire length of cooling mechanism 4A (see FIG. 5), the internal space of chamber 42 is secured widely over substantially the entire length of cooling mechanism 4A, thereby further increasing the flow rate of oil flowing into chamber 42. This further increases the pressure of the oil within chamber 42 and the flow rate of the oil sent out to outlet OP, thereby further increasing the injection speed of the oil injected toward coil end 20. Therefore, with the above configuration, oil can be more reliably applied to both coil ends 21, 22 in top region 23.

[0052] Furthermore, as described above, the bottom plate member 51 of the cooling mechanism 4A is separate from the main body 50, and the injection flow path 59 is arranged to penetrate the bottom plate member 51 in the thickness direction (see Figures 4 and 6), so that the injection flow path 59 can be easily formed by punching or the like.

[0053] However, the present invention is not limited to the above, and the main body 50 and bottom plate member 51 of the cooling mechanism 4A may be integrally formed. Furthermore, as long as the shape of the chamber 42 of the cooling mechanism 4A is as described above and oil is applied to the coil ends 20, the opening directions of the inlet port IP and the injection port OP, the extension direction of the injection flow path 59, etc. are not important.

[0054] Fig. 11 is a diagram for explaining the Coanda phenomenon. Fig. 12 is a graph showing an example of fluctuations in the supply amount by oil pump P over time. The cooling mechanisms 4A and 4B described above, together with oil pump P and control unit CU (see Fig. 1), constitute a cooling unit.

[0055] Incidentally, one possible way to increase the area onto which oil is sprayed (oil spray area) on the coil end 20 is to increase the number of injection ports OP of the cooling mechanism 4A. However, as the number of injection ports OP increases, the distance between adjacent injection ports OP, i.e., the distance between the oil columns sprayed from these injection ports OP, becomes narrower. This can lead to the phenomenon of adjacent oil columns OC1, OC2 being attracted to each other (the so-called Coanda phenomenon), as shown in Figure 11. In Figure 11, the oil columns OC1, OC2 that are not attracted to each other are shown by dashed lines. When the Coanda phenomenon occurs, the two adjacent oil columns OC1, OC2 are combined into a single oil column OC, reducing the effectiveness of increasing the number of injection ports OP to increase the oil spray area on the coil end 20.

[0056] To suppress the Coanda phenomenon, the control unit CU in this embodiment periodically varies the flow rate (supply amount) of oil supplied by the oil pump P to the inlet IP of the cooling mechanism 4A. Specifically, the control unit CU increases or decreases the supply rate of the oil from the oil pump P so as to vary the flow rate of the oil introduced into the inlet IP. For example, as shown in FIG. 12 , the control unit CU increases or decreases the supply rate of oil from the oil pump P in a sinusoidal manner over time. By varying the supply rate from the oil pump P in this manner, fluctuations (pulsations) are imparted to the oil sprayed from the injection nozzles OP, causing variations in the direction of travel of the oil within the chamber 42. Due to this variation, the direction of the oil sprayed from each injection nozzle OP changes randomly, making it easier for two oil columns sprayed from adjacent injection nozzles OP to separate even when they approach each other. Therefore, the Coanda phenomenon can be suppressed even when the number of injection nozzles OP is increased to increase the oil spray area on the coil end 20.

[0057] Furthermore, by varying the amount of oil supplied by the oil pump P as described above, the direction of oil spray from the injection ports OP changes, which has the secondary effect of increasing the oil spray area of ​​the oil sprayed from each injection port OP.

[0058] Furthermore, considering that the shorter the length of the injection flow path 59 connecting the outlet 46 of the chamber 42 and the injection port OP, the more easily the injection direction of the oil from the injection port OP is affected by the direction of movement of the oil inside the chamber 42, when variations in the oil flow direction inside the chamber 42 are caused by fluctuations in the amount of oil supplied as described above, it is preferable to appropriately shorten the length of the injection flow path 59. This increases the change in the direction of injection of the oil from the injection port OP due to variations in the direction of movement of the oil inside the chamber 42, making it possible to more efficiently suppress the Coanda phenomenon.

[0059] The above-described embodiments are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of the present invention should not be interpreted solely by the above-described embodiments and examples, but should be defined by the claims. Furthermore, all modifications and variations within the scope of the claims are within the scope of the present invention. [Explanation of symbols]

[0060] A Motor Unit 1 motor 12 Stator 13 Stator core 2 coils 20 Coil end 23 Top area 4A,4B Cooling mechanism IP Inlet OP nozzle 42 Chamber 43 Ceiling Wall 44 Bottom wall 45 Inlet 46 Outlet 48 First Side Wall 49 Second side wall R1 1st area R2 2nd area 50 main unit 51 Bottom plate member 59 Injection channel P Oil pump (supply section) CU control unit L lengthwise W width direction δ axis direction V vertical direction T transverse direction

Claims

1. A cooling mechanism that discharges a refrigerant toward a coil end that is a part of a coil attached to a stator core and protrudes from the stator core in the axial direction, 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 in a horizontal direction; an inlet through which the refrigerant introduced through the inlet flows in is provided in a ceiling wall of the chamber, while an outlet through which the refrigerant flows out to the injection port is provided in a bottom wall of the chamber; the bottom wall is inclined downward from a portion immediately below the inlet toward a first side wall disposed at one end of the chamber in the width direction so that the refrigerant flowing down from the inlet flows in one direction in the width direction perpendicular to the longitudinal direction of the chamber, A cooling mechanism in which the internal space of the chamber is formed such that, when viewed in the longitudinal direction of the chamber, a first region between the first side wall and the inlet is wider than a second region between the inlet and a second side wall located at the other end of the chamber in the width direction.

2. The cooling mechanism according to claim 1 , a cooling mechanism in which an injection flow path connecting the outlet and the injection port is inclined downward and inward in the axial direction from the outlet to the injection port.

3. 3. The cooling mechanism according to claim 2, The cooling mechanism, wherein the tip of the injection port is formed to taper inward in the axial direction.

4. The cooling mechanism according to claim 1 , the cooling mechanism extends in a transverse direction perpendicular to the axial direction and the up-down direction over the entire length of a top region of the coil end, the top region being visible when the coil end is viewed from directly above, so that the coolant is applied to the entire top region of the coil end; The chamber extends from one end to the other end of the cooling mechanism in the transverse direction.

5. The cooling mechanism according to claim 1 , The chamber is formed by being surrounded by a hollow, bottomless main body and a bottom plate member separate from the main body, The cooling mechanism includes a jet flow path that connects the outlet and the jet port and penetrates the bottom plate member in a thickness direction of the bottom plate member.

6. The cooling mechanism according to claim 1; a supply unit that supplies the refrigerant to the inlet of the cooling mechanism; A cooling unit including a control unit that controls the supply unit, The control unit periodically varies the flow rate of the refrigerant supplied to the inlet by the supply unit.

7. A motor unit comprising: the cooling mechanism according to claim 1; and a stator having the stator core to which the coil is attached.

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