Cooling structure

Abstract

To uniformize a flow rate or a flow velocity of a coolant at each position in an axial direction of a motor.SOLUTION: A cooling structure for a motor extending in an axial direction comprises a coolant flow passage in which a coolant flows in a circumferential direction of the motor, and a supply port through which the coolant is supplied to the coolant flow passage. The coolant flow passage includes: an expansion part which extends in the circumferential direction while being spread from the supply port in the axial direction; and a branch part which extends from the expansion part in the circumferential direction and is branched into a plurality of branch flow passages. The expansion part has a first protrusion which extends in the axial direction and reduces a width of the coolant flow passage in a radial direction of the motor.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a cooling structure for a motor. [Background technology]

[0002] Patent Document 1 discloses a cylindrical support member that supports the outer peripheral surface of a stator core of a motor and forms a flow path through which a cooling fluid passes. According to Patent Document 1, the support member has a cylindrical inner wall portion, a cylindrical outer wall portion facing the radially outer side of the inner wall portion and also having a cylindrical shape, and one or more dividing walls that extend radially between the inner wall portion and the outer wall portion and divide the flow path formed between the inner wall portion and the outer wall portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 020468 Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors of the present application have considered the following cooling structure. This cooling structure includes a refrigerant flow path that allows a refrigerant to flow in the circumferential direction of a motor, and a supply port that supplies the refrigerant to the refrigerant flow path. The refrigerant flow path has an expansion section that extends circumferentially while widening in the axial direction from the supply port, and a branch section that extends circumferentially from the expansion section and branches into multiple branch flow paths. In this cooling structure, it is effective to uniform the flow rate and / or flow velocity of the refrigerant at the branch section in the axial direction of the motor. In light of this, this specification provides technology that contributes to uniforming the flow rate and / or flow velocity of the refrigerant. [Means for solving the problem]

[0005] This specification discloses a cooling structure for a motor extending in the axial direction. The cooling structure includes a refrigerant flow path that flows a refrigerant in the circumferential direction of the motor and a supply port that supplies the refrigerant to the refrigerant flow path. The refrigerant flow path has an expansion portion that widens in the axial direction from the supply port and extends in the circumferential direction, and a branch portion that extends in the circumferential direction from the expansion portion and branches into multiple branch flow paths. The expansion portion has a first protrusion that extends in the axial direction and narrows the width of the refrigerant flow path in the radial direction of the motor.

[0006] According to the above configuration, a portion of the refrigerant supplied from the supply port to the expansion section is blocked by the first protrusion and temporarily stagnates within the expansion section. This temporary stagnation equalizes the flow resistance acting on the refrigerant in the axial direction within the expansion section, and the flow rate and / or flow velocity of the refrigerant flowing downstream of the first protrusion, i.e., the flow rate and / or flow velocity of the refrigerant flowing through the branch section, in the axial direction. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a simplified view showing a configuration including a motor according to an embodiment, viewed from an axial direction. [Figure 2] Cross-sectional view taken along line II-II in Figure 1. [Figure 3] FIG. [Figure 4] FIG. 10 is a perspective view showing the shape of the expansion portion from a radially inner side. [Figure 5] 1 is a cross-sectional view of the extension portion taken along a plane perpendicular to the axial direction. [Figure 6] 6 is a cross-sectional view of an extension portion different from that of FIG. 5 taken along a plane perpendicular to the axial direction. [Figure 7] 5 is a perspective view showing the shape of an extension portion different from that of FIG. 4 as viewed from the inside in the radial direction. [Figure 8] FIG. [Figure 9] FIG. 10 is a view showing a branching portion shape according to a modified example from a perspective facing in the radial direction. [Figure 10]FIG. 10 is a diagram showing a simplified configuration of a motor casing according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of the present technology will be described with reference to the drawings. Each drawing is merely an example, and the present embodiment is not limited to the contents shown in the drawings. Furthermore, since each drawing is an example, the shapes shown may not be accurate, may not match each other, or some parts may be omitted.

[0009] FIG. 1 shows a simplified configuration including a motor 10 from a perspective facing the axial direction of the motor 10. FIG. 2 is a cross-sectional view of the configuration shown in FIG. 1 taken along line II-II. As shown in FIG. 1, the motor 10 includes a stator core 11, coils 12, a rotor 13, and a shaft 14. The stator core 11 is roughly cylindrical, and the coils 12 are wound around the stator core 11. The detailed shape of the stator core 11 is not important here. The rotor 13 is disposed in the space surrounded by the stator core 11. The rotor 13 is attached to a shaft 14 located at the center of the motor 10, i.e., on the motor axis Z. The shaft 14 transmits the rotational motion of the rotor 13 to the outside.

[0010] The motor casing 20 has a cylindrical shape extending along the axial direction. The outer peripheral surface of the stator core 11 is in contact with the inner peripheral surface of the motor casing 20, and the stator core 11 is fixed to the inner peripheral surface of the motor casing 20. In other words, the motor casing 20 supports the stator core 11 from the outside in the radial direction of the motor 10 (hereinafter referred to as the radial direction) based on the motor axis Z. The motor casing 20 may be considered as part of the configuration of the motor 10. In this case, the motor casing 20 corresponds to an example of the cylindrical member 18 of the present technology.

[0011] As shown in Fig. 2, the motor casing 20 has an inner wall portion 23 on the radially inner side, and an outer wall portion 24 that faces the inner wall portion 23 and is located radially outward of the inner wall portion 23. The stator core 11 is fixed to the inner wall portion 23 of the motor casing 20. A refrigerant flow path 30 is formed inside the motor casing 20, i.e., between the inner wall portion 23 and the outer wall portion 24, through which a refrigerant flows in the circumferential direction of the motor 10 (hereinafter referred to as the circumferential direction R) that extends in the direction of the motor axis Z (hereinafter referred to as the axial direction). The inner circumferential surface of the refrigerant flow path 30 is defined by the inner wall portion 23, and the outer circumferential surface of the refrigerant flow path 30 is defined by the outer wall portion 24.

[0012] The inner wall 23 and the outer wall 24 are connected on one axial side and the other axial side by end walls 25, 26 extending in the radial direction. Therefore, the refrigerant flow path 30 is defined by the inner wall 23, the outer wall 24, and the end walls 25, 26. In this embodiment, these structures of the motor casing 20 that define the refrigerant flow path 30 correspond to the cooling structure of the motor 10. Simply put, the motor casing 20 can also be considered as the cooling structure. A refrigerant is a fluid that has a cooling effect, and here it is assumed to be cooling water. However, the refrigerant may also be, for example, cooling oil.

[0013] The motor casing 20 has a supply port 21 that receives a supply of refrigerant and a discharge port 22 that discharges the refrigerant. The supply port 21 and the discharge port 22 are each connected to a refrigerant flow path 30. The supply port 21 supplies the refrigerant to the refrigerant flow path 30 from the outside. The discharge port 22 discharges the refrigerant that has been supplied from the supply port 21 and flowed through the refrigerant flow path 30 to the outside. The refrigerant circulates through the refrigerant flow path 30 and a flow path outside the motor casing 20 (not shown) under pressure from a pump (not shown).

[0014] The refrigerant flow path 30 includes an expansion section 31 communicating with the supply port 21, a reduction section 32 communicating with the discharge port 22, and a branch section 33 extending in the circumferential direction R and connecting the expansion section 31 and the reduction section 32. The branch section 33 extends from the expansion section 31 in the circumferential direction R and branches into multiple branch flow paths 330. The branch section 33 can also be considered as a collection of multiple branch flow paths 330. The expansion section 31 and the reduction section 32 are separated by a partition wall 34, so the expansion section 31 and the reduction section 32 are not directly connected. All of the refrigerant that flows from the supply port 21 into the expansion section 31 flows through the branch section 33, then flows into the reduction section 32, and is discharged from the discharge port 22.

[0015] 3 is a perspective view showing the shape (refrigerant flow path shape) 30S of the refrigerant flow path 30. The refrigerant flow path shape 30S is the shape of a space formed inside the motor casing 20. In other words, the refrigerant flow path 30 is formed by the walls inside the motor casing 20, including the supply port 21 and the discharge port 22, and the refrigerant flow path shape 30S is the space defined by these walls. Therefore, the refrigerant flow path shape 30S has a supply port shape 21S, a discharge port shape 22S, an expansion portion shape 31S, a branch portion shape 33S, and a contraction portion shape 32S, which correspond to the supply port 21, the discharge port 22, the expansion portion 31, the branch portion 33, and the contraction portion 32, respectively. A partition wall 34 exists in the gap 34S between the expansion portion shape 31S and the contraction portion shape 32S inside the motor casing 20.

[0016] The refrigerant flow path shape 30S can also be interpreted as the core 50 used to manufacture the motor casing 20. Although details are omitted, the motor casing 20 is cast by setting the core 50 in a mold for manufacturing a cylindrical member and pouring molten metal material into the mold. The core 50 is formed, for example, using salt or sand as a material. After the metal material hardens, the core 50 is broken and removed from the motor casing 20 when it is removed from the mold. As a result, the interior of the motor casing 20 becomes a space with the same shape as the core 50, i.e., the refrigerant flow path shape 30S.

[0017] In the following description, there will be no clear distinction between the components that constitute the refrigerant flow path 30 and the space defined by those components. Therefore, a description of the refrigerant flow path shape 30S also includes a description of the refrigerant flow path 30. Similarly, a description of the supply port shape 21S, the discharge port shape 22S, the expansion portion shape 31S, the branch portion shape 33S, and the contraction portion shape 32S also includes a description of the supply port 21, the discharge port 22, the expansion portion 31, the branch portion 33, and the contraction portion 32, respectively.

[0018] As shown in FIG. 3 , the expansion portion shape 31S extends in the circumferential direction R while widening in the axial direction from the supply port shape 21S. That is, the expansion portion 31 extends in the circumferential direction R from the supply port 21 and gradually expands in width in the axial direction to communicate with the branch portion 33. The branch portion shape 33S extends in the circumferential direction R from the expansion portion shape 31S and branches into multiple branch channels. The contraction portion shape 32S extends in the circumferential direction R while contracting in the axial direction from a position communicating with the branch portion shape 33S, and communicates with the discharge port shape 22S. The axial widths of the expansion portion 31 and the contraction portion 32 at the positions communicating with the branch portion 33 may be interpreted as being substantially the same as the axial width of the branch portion 33. Furthermore, the width of the branch portion 33 may be interpreted as being substantially constant in the axial direction.

[0019] 4 is a perspective view of the extension portion shape 31S as viewed from the radially inner side. The arrow indicated by the symbol D indicates the direction D parallel to the motor axis Z. Therefore, the direction D can be considered the axial direction. FIG. 5 is a cross-sectional view of the extension portion 31 taken along a plane perpendicular to the axial direction.

[0020] According to this embodiment, the expansion section 31 has at least one protrusion 35 that extends in the axial direction and narrows the width of the refrigerant flow path 30 in the radial direction. While FIGS. 4 and 5 show an example in which the expansion section 31 has two protrusions 35, the number of protrusions 35 may be one or three or more. One protrusion 35 may be referred to as the first protrusion 35a, and the other protrusions 35 may be referred to as the second protrusion 35b, etc., to distinguish them from one another. For example, the protrusion 35 located downstream of the supply port 21 is referred to as the first protrusion 35a, and the protrusion 35 located upstream is referred to as the second protrusion 35b. However, the positional relationship between the first protrusion 35a and the second protrusion 35b may be reversed.

[0021] The protrusion 35 extending in the axial direction does not necessarily mean that its longitudinal direction is parallel to the axial direction, but also means that it extends generally along the axial direction. For example, the longitudinal direction of the protrusion 35 may be inclined within a predetermined angle range with respect to the axial direction.

[0022] As shown in FIG. 5, in the extension portion 31, a first protrusion 35a and a second protrusion 35b are formed by a portion of the inner wall portion 23 protruding radially outward. Also, as shown in FIG. 4, a portion of the extension portion shape 31S is a first protrusion shape 35aS corresponding to the first protrusion 35a and a second protrusion shape 35bS corresponding to the second protrusion 35b. As shown in FIG. 4, the first protrusion shape 35aS and the second protrusion shape 35bS are concave in terms of their spatial shapes, but as shown in FIG. 4, the physical shapes of the first protrusion 35a and the second protrusion 35b of the inner wall portion 23 are convex in terms of their physical shapes. At least one protrusion 35 may be formed by a portion of the outer wall portion 24 protruding radially inward.

[0023] 4, it can be seen from the first protrusion shape 35aS and the second protrusion shape 35bS that the first protrusion 35a and the second protrusion 35b are formed continuously in the axial direction from one end to the other end of the expansion portion 31. However, at least one of the protrusions 35 may lack continuity at least at one point in the range from one end to the other end of the expansion portion 31 in the axial direction. Furthermore, when the expansion portion 31 has multiple protrusions 35, the protrusion heights of the respective protrusions 35 may be the same or different. In the example of FIG. 5, the protrusion height in the radial direction of the first protrusion 35a and the protrusion height in the radial direction of the second protrusion 35b are the same.

[0024] Like FIG. 5, FIG. 6 is a cross-sectional view of the extension portion 31 taken along a cut surface perpendicular to the axial direction. Regarding FIG. 6, only the differences from FIG. 5 will be described. In the example of FIG. 6, the radial protrusion height of the first protrusion 35a is different from the radial protrusion height of the second protrusion 35b. Specifically, the protrusion height of the first protrusion 35a is higher than the protrusion height of the second protrusion 35b. It is also possible to make the protrusion height of the second protrusion 35b higher than the protrusion height of the first protrusion 35a.

[0025] 5 and 6, the extension portion 31 can be roughly divided into three ranges in the circumferential direction R by the first protrusion 35a and the second protrusion 35b. Here, the range of the extension portion 31 downstream of the first protrusion 35a is referred to as the first range 36. Furthermore, the range of the extension portion 31 upstream of the first protrusion 35a and downstream of the second protrusion 35b is referred to as the second range 37, and the range upstream of the second protrusion 35b is referred to as the third range 38. If the second protrusion 35b were not present, the range of the extension portion 31 upstream of the first protrusion 35a would be the second range 37.

[0026] As can be seen from FIGS. 5 and 6 , the second region 37 and the third region 38 have larger radial widths than the first region 36. The radial widths of the first region 36, the second region 37, and the third region 38 can also be considered the distance between the inner wall portion 23 and the outer wall portion 24 in the radial direction. This is a result of ensuring the strength of the core 50 as described above. The radial width of the expansion portion shape 31S is narrowed at the positions of the first protrusion shape 35aS and the second protrusion shape 35bS. Therefore, the thickness of the core 50 is appropriately set to compensate for the decrease in strength of the core 50 due to these narrowed portions. As a result, the radial widths of the second region 37 and the third region 38 are larger than that of the first region 36. It is to be understood that the radial widths of the branching portion 33 and the contracting portion 32 of the refrigerant flow path 30 are the same as that of the first region 36. Alternatively, the radial width of the entire coolant flow path 30 may be unified to match the width required for the second region 37 and the third region 38 .

[0027] FIG. 7 shows a perspective view of an example of an extension portion shape 31S different from that shown in FIG. 4, viewed from the radially inner side. The view of FIG. 7 is the same as that of FIG. 4. Descriptions of FIG. 7 common to FIG. 4 will be omitted. According to FIG. 7, the extension portion shape 31S has a first protrusion shape 35aS. That is, according to FIG. 7, it can be seen that the extension portion 31 has at least the first protrusion 35a. According to FIG. 7, the first protrusion shape 35aS is partially bent in the axial direction. That is, the first protrusion 35a is bent at at least one point in the axial direction. The first protrusion 35a may have multiple bent points. Of course, other protrusions 35, such as the second protrusion 35b, may also be bent.

[0028] 7, the first protrusion shape 35aS has a first section shape 40S and a second section shape 41S in the axial direction. The first section shape 40S and the second section shape 41S have different depths. That is, according to FIG. 7, the first protrusion 35a has a first section corresponding to the first section shape 40S and a second section corresponding to the second section shape 41S in the axial direction, and the protrusion height in the radial direction of the first section is different from the protrusion height in the radial direction of the second section. Of course, other protrusions 35, such as the second protrusion 35b, may have multiple sections with different protrusion heights.

[0029] The feature that one protrusion 35 is bent and the feature that one protrusion 35 has multiple sections with different protrusion heights can be understood independently. For example, the first protrusion 35a may not be bent but may have multiple sections with different protrusion heights. Alternatively, for example, the first protrusion 35a may be bent but have a constant protrusion height.

[0030] FIG. 8 shows a perspective view of a portion of the branch portion 33. The branch portion 33 has a plurality of columnar portions 39 arranged at positions spaced apart from each other in the axial direction and the circumferential direction R. Each of the columnar portions 39 extends radially and connects the inner wall portion 23 and the outer wall portion 24 of the motor casing 20. However, for ease of viewing, the outer wall portion 24 and the end walls 25, 26 of the motor casing 20 are omitted from FIG. 8. As shown in FIG. 8, the columnar portion 39 has a circular cross section perpendicular to the radial direction. Therefore, the columnar portion 39 can be regarded as a cylinder. However, the cross section of the columnar portion 39 may be a polygon, such as a hexagon or octagon.

[0031] Due to the presence of the multiple columnar portions 39, the branch portion 33 branches into multiple branch flow paths 330. In other words, the multiple branch flow paths 330 connect the expansion portion 31 and the contraction portion 32 while repeatedly separating and merging with each other. As can be seen from FIG. 8, each of the multiple hole shapes 39S of the branch portion shape 33S shown in FIGS. 3, 4, and 7 has a columnar portion 39 within the motor casing 20. Also, as shown in FIG. 2, each cross section that exists at regular intervals in the axial direction in the branch portion 33 can be interpreted as a cross section of each columnar portion 39.

[0032] Fig. 9 shows a part of the branch portion shape 33S from a perspective facing the radial direction. According to the example of Fig. 9, the plurality of hole shapes 39S of the branch portion shape 33S are elliptical shapes that are long in the circumferential direction R. That is, as can be seen from Fig. 9, at least one of the plurality of columnar portions 39 in the branch portion 33 may have an elliptical cross section perpendicular to the radial direction.

[0033] In Fig. 10, the upper part of the drawing shows a simplified view of the configuration of the motor casing 20 as seen from the radially outer side. However, for ease of viewing, the outer wall portion 24 is omitted from the upper part of Fig. 10. The two-dot chain circles in Fig. 10 indicate the positions of the supply port 21 and the discharge port 22. Furthermore, the lower part of Fig. 10 shows a cross-sectional view of the branch portion 33 taken along a plane perpendicular to the circumferential direction R.

[0034] The branch portion 33 may have a plurality of middle wall portions 42 as shown in the example of FIG. 10 , instead of the plurality of columnar portions 39 described above. Each of the plurality of middle wall portions 42 connects the inner wall portion 23 and the outer wall portion 24 and extends in the circumferential direction R. The middle wall portions 42 are spaced apart from one another in the axial direction. The presence of such a plurality of middle wall portions 42 causes the branch portion 33 to branch into a plurality of branch flow paths 330. Each of the branch flow paths 330 separated by the middle wall portions 42 connects the expansion portion 31 and the contraction portion 32. Basically, each of the plurality of middle wall portions 42 extends over the entire range of the branch portion 33 in the circumferential direction R. However, as shown in FIG. 10 , the start positions of the plurality of middle wall portions 42 on the expansion portion 31 side may be at least partially offset in the circumferential direction R. The middle wall portions 42 may not be parallel to the circumferential direction R, but may be slightly inclined relative to the circumferential direction R.

[0035] Furthermore, in the example of Figure 10, the expansion section 31 has a narrowed section 43 in a part of the circumferential direction R. The narrowed section 43 is a range in which the rate of expansion in the axial direction with respect to changes in position in the circumferential direction R is smaller than at other positions in the expansion section 31. The rate of expansion in the axial direction with respect to changes in position in the circumferential direction R can also be referred to as the expansion rate of the expansion section 31. Of course, a configuration in which the expansion section 31 has a narrowed section 43 can also be applied to a configuration in which the branch section 33 has a columnar section 39.

[0036] Although not shown in FIG. 10 , according to this embodiment, the expansion portion 31 has one or more protrusions 35 as described above. The positional relationship between the protrusions 35 and the throttling portions 43 may vary. In the expansion portion 31, the throttling portion 43 may be located upstream of a certain protrusion 35 or downstream of that protrusion 35. Alternatively, at least one protrusion 35 may be formed in the throttling portion 43. For example, the throttling portion 43 may be formed in the second region 37 shown in FIGS. 5 and 6 . Furthermore, the expansion portion 31 may have a shape having the throttling portions 43 at multiple positions in the circumferential direction R.

[0037] As described above, according to this embodiment, the cooling structure of the motor 10 extending in the axial direction includes a refrigerant flow path 30 that flows a refrigerant in the circumferential direction R of the motor 10, and a supply port 21 that supplies a refrigerant to the refrigerant flow path 30. The refrigerant flow path 30 has an expansion portion 31 that extends in the circumferential direction R while widening in the axial direction from the supply port 21, and a branch portion 33 that extends from the expansion portion 31 in the circumferential direction R and branches into multiple branch flow paths 330. The expansion portion 31 has a first protrusion 35a that extends in the axial direction and narrows the width of the refrigerant flow path 30 in the radial direction of the motor 10.

[0038] According to the above configuration, a portion of the refrigerant supplied from the supply port 21 to the expansion section 31 is blocked by the first protrusion 35a and tends to temporarily stagnate within the expansion section 31. The refrigerant then flows downstream of the first protrusion 35a and toward the branch section 33. This temporary stagnation equalizes the flow resistance acting on the refrigerant in the axial direction within the expansion section 31. As a result, the flow rate and / or flow velocity of the refrigerant flowing downstream of the first protrusion 35a are uniform at any position in the axial direction within the refrigerant flow path 30, reducing uneven cooling of the motor 10.

[0039] Moreover, according to one embodiment, the expansion portion 31 further includes a second protrusion 35b that extends in the axial direction and narrows the width of the refrigerant flow path 30 in the radial direction of the motor 10. Furthermore, the second protrusion 35b may be positioned between the supply port 21 and the first protrusion 35a in the circumferential direction R. According to the above configuration, the expansion section 31 has the second protrusion 35b in addition to the first protrusion 35a, which further enhances the effect of temporarily retaining the refrigerant before it flows to the branch section 33, thereby making the flow rate and / or flow velocity uniform in the axial direction.

[0040] Furthermore, according to one embodiment, the radial height of the first protrusion 35a is different from the radial height of the second protrusion 35b. That is, the protrusion heights of the multiple protrusions 35 may be different. By making the protrusion heights of the first protrusion 35a and the second protrusion 35b different, it becomes easier to control the flow rate and flow speed of the refrigerant flowing to the branch portion 33.

[0041] Moreover, according to one embodiment, the first protrusion 35a is bent at least at one point in the axial direction. According to the above configuration, by forming the first protruding portion 35a in a bent shape, it becomes easier to control the flow rate and flow speed of the refrigerant flowing downstream of the first protruding portion 35a.

[0042] Furthermore, according to one embodiment, the first protrusion 35a has a first section and a second section in the axial direction, and the protruding height in the radial direction of the first section is different from the protruding height in the radial direction of the second section. According to the above configuration, by changing the protruding height of each section of the first protruding portion 35a, it becomes easier to control the flow rate and flow speed of the refrigerant flowing downstream of the first protruding portion 35a.

[0043] Furthermore, according to one embodiment, the first protrusion 35a is formed continuously from one end to the other end of the expansion portion 31 in the axial direction. According to this configuration, the flow rate and / or flow speed of the coolant flowing downstream of the first protruding portion 35a can be more accurately made uniform at each position in the axial direction.

[0044] Furthermore, according to one embodiment, the radial width of the portion of the extension portion 31 upstream of the first protrusion 35a is greater than the radial width of the portion of the extension portion 31 downstream of the first protrusion 35a. According to the above configuration, as described above, it can be said that the refrigerant flow path 30 is formed using the core 50 that has an appropriate strength.

[0045] According to one embodiment, the motor 10 includes a cylindrical member 18 having a refrigerant flow path 30. The cylindrical member 18 has an inner wall 23 that defines the inner circumferential surface of the refrigerant flow path 30, and an outer wall 24 that defines the outer circumferential surface of the refrigerant flow path 30. The cylindrical member 18 further includes a plurality of columnar portions 39 located at a branch portion 33 and each extending between the inner wall portion 23 and the outer wall portion 24. According to the above configuration, the branch section 33 branches into a plurality of branch flow paths 330 by a plurality of pillar-shaped sections 39. The cross section of the pillar-shaped sections 39 perpendicular to the radial direction of the motor 10 may have various shapes, such as a circle or a polygon. Furthermore, at least one of the plurality of pillar-shaped sections 39 may have an elliptical cross section perpendicular to the radial direction.

[0046] Also, according to one embodiment, the motor 10 includes a cylindrical member 18 having a refrigerant flow path 30. The cylindrical member 18 has an inner wall portion 23 that defines the inner circumferential surface of the refrigerant flow path 30, and an outer wall portion 24 that defines the outer circumferential surface of the refrigerant flow path 30. The cylindrical member 18 further includes a plurality of middle wall portions 42 that are located at the branching portion 33, connect the inner wall portion 23 and the outer wall portion 24, extend in the circumferential direction R, and are spaced apart from each other in the axial direction. According to the above configuration, the branch portion 33 branches into a plurality of branch flow paths 330 by a plurality of middle wall portions 42 .

[0047] Moreover, according to one embodiment, the cylindrical member 18 is a motor casing 20 that supports the stator core 11 of the motor 10 from the radially outer side. According to the above configuration, when manufacturing the motor casing 20, the cooling structure of the motor 10 can be easily realized by forming the coolant flow path 30 inside the motor casing 20.

[0048] However, forming the refrigerant flow path 30 between the inner wall portion 23 and the outer wall portion 24 of the motor casing 20 is merely one example. For example, the motor casing 20 as the cylindrical member 18 may be configured without the inner wall portion 23. The refrigerant flow path 30 may be formed between the outer peripheral surface of the stator core 11 and the outer wall portion 24 of the motor casing 20 by shaping either or both of the outer peripheral surface of the stator core 11 and the outer wall portion 24 of the motor casing 20 that faces the outer peripheral surface.

[0049] Moreover, according to one embodiment, the expansion portion 31 has a narrowed portion 43 in a part of the circumferential direction R. The narrowed portion 43 has a smaller rate of expansion in the axial direction with respect to changes in the circumferential direction R than other positions of the expansion portion 31. According to the above configuration, by providing a throttling section 43 in part of the expansion section 31, the flow of refrigerant toward the branch section 33 can be prevented from being dispersed too much to both ends in the axial direction, and an appropriate flow rate in the central part in the axial direction can also be ensured.

[0050] Although specific examples of the technology disclosed in this specification have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. Furthermore, the technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings simultaneously achieves multiple objectives, and achieving one of those objectives itself has technical utility. [Explanation of symbols]

[0051] 10: Motor, 11: Stator core, 12: Coil, 13: Rotor, 14: Shaft, 18: Cylindrical member, 20: Motor casing, 21: Supply port, 22: Discharge port, 23: Inner wall portion, 24: Outer wall portion, 25, 26: End wall portion, 30: Refrigerant flow path, 31: Expansion portion, 32: Contraction portion, 33: Branch portion, 34: Partition wall, 35: Protrusion portion, 35a: First protrusion portion, 35b: Second protrusion portion, 36: First region, 37: Second region, 38: Third region, 39: Columnar portion, 42: Middle wall portion, 43: Constriction portion, 330: Branch flow path

Claims

1. A cooling structure for an axially extending motor, a refrigerant flow path through which a refrigerant flows in a circumferential direction of the motor; a supply port for supplying the refrigerant to the refrigerant flow path, The refrigerant flow path is an expansion portion that expands in the axial direction from the supply port and extends in the circumferential direction; a branch portion extending from the expansion portion in the circumferential direction and branching into a plurality of branch flow paths, The expansion portion has a first protrusion that extends in the axial direction and narrows the width of the refrigerant flow path in the radial direction of the motor.

2. the expansion portion further includes a second protrusion portion that extends in the axial direction and narrows the width of the refrigerant flow path in a radial direction of the motor, The cooling structure according to claim 1 , wherein the second protrusion is located between the supply port and the first protrusion in the circumferential direction.

3. The cooling structure according to claim 2 , wherein a protruding height of the first protruding portion in the radial direction is different from a protruding height of the second protruding portion in the radial direction.

4. The cooling structure according to claim 1 , wherein the first protrusion is bent at least at one point in the axial direction.

5. the first protrusion has a first section and a second section in the axial direction, The cooling structure according to claim 1 , wherein a protruding height of the first section in the radial direction is different from a protruding height of the second section in the radial direction.

6. The cooling structure according to claim 1 , wherein the first protrusion is formed continuously from one end to the other end of the extension portion in the axial direction.

7. The cooling structure according to claim 1 , wherein a radial width of a portion of the extension portion upstream of the first protrusion is greater than a radial width of a portion of the extension portion downstream of the first protrusion.

8. the motor includes a cylindrical member in which the refrigerant flow path is provided, The cylindrical member is an inner wall portion defining an inner circumferential surface of the refrigerant flow path; an outer wall portion defining an outer circumferential surface of the refrigerant flow path; The cooling structure of claim 1 , further comprising: a plurality of pillars located at the bifurcation and each pillar extending between the inner wall and the outer wall.

9. The cooling structure according to claim 8 , wherein at least one of the plurality of columnar portions has an elliptical cross section perpendicular to the radial direction.

10. the motor includes a cylindrical member in which the refrigerant flow path is provided, The cylindrical member is an inner wall portion defining an inner circumferential surface of the refrigerant flow path; an outer wall portion defining an outer circumferential surface of the refrigerant flow path; 2. The cooling structure according to claim 1, further comprising: a plurality of middle wall portions located at the branch portion, each of the middle wall portions extending in the circumferential direction and connecting between the inner wall portion and the outer wall portion, the plurality of middle wall portions being spaced apart from one another in the axial direction.

11. The cooling structure according to any one of claims 8 to 10, wherein the cylindrical member is a motor casing that supports a stator core of the motor from the radially outer side.

12. the expansion portion has a narrowed portion in a part in the circumferential direction, The cooling structure according to claim 1 , wherein the rate at which the constricted portion expands in the axial direction relative to the change in the circumferential direction is smaller than that at other positions of the expanded portion.

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