WO2025211107A1 - Rotary machine - Google Patents

Abstract

A rotary machine (10) comprises a stator (30), a rotor (40), and cooling piping (60). The stator (30) has an annular shape and generates a rotating magnetic field. The rotor (40) is disposed so that an axial gap is provided with respect to the stator (30). The cooling piping (60) has, in the interior thereof, a passage (60a) through which cooling liquid flows. Furthermore, the cooling piping (60) is thermally connected to a stator inner peripheral surface (33b), which is the annular inner peripheral surface of the stator (30).

Description

Rotating machines CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on Patent Application No. 2024-060445, filed in Japan on April 3, 2024, and the contents of the original application are incorporated by reference in their entirety.

The disclosure in this specification relates to a rotating machine having a stator and a rotor.

Patent Document 1 describes a rotating machine that includes a stator and a rotor. The stator has a core and windings wound around the core. In this rotating machine, the core and windings are cooled by immersing them in a coolant. Specifically, the rotating machine includes a channel structure that forms part of the coolant circulation path. The core and windings are housed inside the channel structure together with the coolant.

Special Publication No. 2022-539771

However, the above-mentioned channel structure is required to have a sealed structure that prevents coolant leakage while accommodating the core and windings inside. This means that the channel structure has a complex sealing structure. For example, the wiring that supplies power to the windings needs to be routed from the outside to the inside of the channel structure, necessitating a complex sealing structure between the wiring and the channel structure.

One disclosed objective is to provide a rotating machine that can cool the stator with a simple structure.

In order to achieve the above object, a rotating machine according to one aspect of the present disclosure includes:
an annular stator that generates a rotating magnetic field;
a rotor disposed relative to the stator so as to provide an axial gap;
The rotor includes a cooling pipe that is thermally connected to the annular inner peripheral surface of the stator and has a passage therein through which a cooling liquid flows.

In the rotating machine disclosed herein, cooling piping is connected to the annular inner peripheral surface of the stator. This allows the stator to be cooled without being immersed in a cooling liquid. Furthermore, the stator can be efficiently cooled from the annular inner side of the stator, where heat tends to build up. Therefore, the stator can be sufficiently cooled despite the simple structure.

Note that the reference numbers in parentheses above merely indicate an example of the correspondence with the specific configurations in the embodiments described below, and do not in any way limit the technical scope.

FIG. 2 is a schematic diagram of an EPU according to the first embodiment. FIG. 2 is a cross-sectional view of the motor shown in FIG. 1 . FIG. 3 is a plan view of the rotor shown in FIG. 2 as viewed from the axial direction. FIG. 3 is a perspective view of a portion of the stator shown in FIG. 2 . 3 is a cross-sectional view taken along the line VV in FIG. 2. FIG. 3 is a perspective view of the stator core and connecting piping shown in FIG. 2 . FIG. 10 is a cross-sectional view showing a stator and cooling piping according to a second embodiment. FIG. 11 is a schematic view of a stator, cooling pipes, and connecting pipes according to a third embodiment, as viewed from the axial direction. FIG. 11 is a perspective view showing cooling pipes and connecting pipes according to a third embodiment. FIG. 10 is a perspective view showing a stator, cooling pipes, and connecting pipes according to a fourth embodiment. FIG. 11 is a schematic view of a stator, cooling pipes, and connecting pipes according to a fifth embodiment, as viewed from the axial direction. FIG. 13 is a schematic view of a stator, cooling pipes, and connecting pipes according to a sixth embodiment, as viewed from the axial direction. FIG. 13 is a schematic diagram of an EPU according to a seventh embodiment. FIG. 13 is a schematic view of a heat exchanger according to a seventh embodiment, viewed from the axial direction. FIG. 13 is a schematic diagram of an EPU according to an eighth embodiment. FIG. 13 is a schematic view of a heat exchanger according to an eighth embodiment, viewed from the axial direction.

Below, several embodiments for implementing the present disclosure will be described with reference to the drawings. In each embodiment, parts corresponding to matters described in the preceding embodiment will be assigned the same reference numerals, and duplicate explanations may be omitted. In each embodiment, where only part of the configuration is described, other previously described embodiments may be applied to the remaining parts of the configuration. In addition to combinations of parts that are specifically stated as being possible in each embodiment, it is also possible to partially combine embodiments even if not explicitly stated, as long as there are no particular problems with the combination.

(First embodiment)
The propeller 2 shown in Figure 1 is mounted on an aircraft. The aircraft in question is a vertical take-off and landing (eVTOL). eVTOL is an abbreviation for Electric Vertical Take-off and Landing. The propeller in question may be a propeller that generates flight thrust during vertical take-off and landing or hovering, or a propeller that generates flight thrust during cruising in horizontal flight.

The propeller 2 is driven to rotate by an electric propulsion unit (EPU 3). EPU is an abbreviation for Electric Propulsion Unit. The EPU 3 includes a rotating machine 10, a cooler 70, an inverter device 80, an air-cooled duct 90, etc. The inverter device 80 converts DC power stored in a battery (not shown) installed on the eVTOL into AC power and supplies it to the rotating machine 10. The rotating shaft 50 of the rotating machine 10 is connected to a reducer 4 and is slowed down. The output shaft 4a of the reducer 4 transmits the reduced rotational force to the propeller 2.

An air-cooled fan 5 is attached to the rotating shaft 50. The air-cooled fan 5 rotates around the rotating shaft 50 and blows air into the air-cooled duct 90. The air-cooled duct 90 has a cylindrical shape extending in the direction of the rotation axis. Note that the rotation axis direction is the direction along the rotation center line C of the rotating shaft 50. In this specification, the rotation axis direction is sometimes simply referred to as the axial direction. The rotating machine 10, inverter device 80, and heat exchanger 71, which will be described later, are arranged inside the air-cooled duct 90.

The propeller 2, reducer 4, air-cooled fan 5, rotating machine 10, inverter device 80, and heat exchanger 71 are arranged in the axial direction. In the example shown in Figure 1, the air-cooled fan 5 blows air in a direction that pushes outside air into the air-cooled duct 90, as indicated by the arrow in the figure. However, the air-cooled fan 5 may also blow air in a direction that draws air from the air-cooled duct 90.

The rotating machine 10, inverter unit 80, and heat exchanger 71 each have heat dissipation fins F10, F80, and F70. Outside air blown by the air-cooling fan 5 flows in through the inlet 90a of the air-cooling duct 90, exchanges heat with the heat dissipation fins F10, F80, and F70, and then flows out through the outlet 90b. As a result, the rotating machine 10, inverter unit 80, and heat exchanger 71 are air-cooled by exchanging heat with the outside air. The heat dissipation fins F10, F80, and F70 are plate-shaped and extend in the axial and radial directions. Multiple heat dissipation fins F10, F80, and F70 are arranged in a row in the circumferential direction. Note that in the diagram, the symbol AD indicates the axial direction, and the symbol RD indicates the radial direction.

The rotating machine 10 shown in Figure 2 is a motor device that is driven to rotate by being supplied with AC power. The rotating machine 10 includes a case 20, a stator 30, a rotor 40, a rotating shaft 50, a bearing BR, etc.

The case 20 is a metal housing that houses the stator 30 and rotor 40. A pair of bearings BR are attached to the case 20. The bearings BR hold the rotating shaft 50 in the case 20 in a rotatable state.

As shown in Figure 3, the rotor 40 is positioned so that an axial gap is provided with respect to the stator 30. In this embodiment, the rotors 40 are positioned on both sides of the stator 30 in the direction of the rotation axis. The rotor 40 has multiple magnets 41 and a metallic rotor body 42.

The magnets 41 are arranged at equal intervals in the circumferential direction of rotation. The surfaces of the magnets 41 that face the stator 30 are exposed from the rotor main body 42. The aforementioned axial gap is formed between the exposed surfaces of the magnets 41 and the stator core 31 of the stator 30.

The rotor body 42 is disk-shaped and holds the magnet 41. An axial hole 42a is formed in the center of the rotor body 42. The rotating shaft 50 is inserted into the axial hole 42a. Multiple through holes 42b are formed in the rotor body 42 around the axial hole 42a. Bolts BT are inserted into the through holes 42b. The multiple through holes 42b are formed at equal intervals in the circumferential direction.

The rotating shaft 50 is made of metal and has a shaft main body 51 and a fastening portion 52. A portion of the shaft main body 51 is inserted into the shaft hole 42a. A portion of the shaft main body 51 is supported by a bearing BR. The fastening portion 52 extends radially from the shaft main body 51 and faces the rotor main body 42. The fastening portion 52 has multiple threaded holes for fastening with bolts BT. With this bolt fastening, the rotating shaft 50 is connected to the two rotors 40 and rotates integrally with the rotors 40.

As shown in Figure 4, the stator 30 has a stator core 31, windings 32, and a resin body 33. The stator core 31 has a core 311 and a bobbin 312. The core 311 is constructed by stacking multiple electromagnetic steel plates in the axial direction. The bobbin 312 is electrically insulating and is attached to the core 311. The windings 32 are wound around the core 311 via the bobbin 312. A magnetic field generated by passing current through the windings 32 is emitted to the outside of the stator 30 through the stator core 31. The magnetic field emitted in this manner rotates when current is switched on and off to the coils of each phase. In this way, the stator 30 generates a rotating magnetic field.

As shown in FIG. 5, winding 32 includes portions that function as U-phase coils U1 and U2, V-phase coils V1 and V2, and W-phase coils W1 and W2. The U-phase coils U1 and U2, V-phase coils V1 and V2, and W-phase coils W1 and W2 are star-connected or delta-connected. The U-phase coils U1 and U2, V-phase coils V1 and V2, and W-phase coils W1 and W2 include the U-phase coil U1, V-phase coil V1, and W-phase coil W1 of a first group, and the U-phase coil U2, V-phase coil V2, and W-phase coil W2 of a second group. The coils of the first group and the coils of the second group are arranged alternately in the circumferential direction.

By providing a first group and a second group, redundancy is ensured. In other words, even if an abnormality such as a broken wire occurs in one group, the rotation of the rotating shaft 50 can continue by passing current through the other group, and the rotation of the propeller 2 can also continue. When current is passed through either group to drive the rotor 40, the rotating machine 10 functions as a three-phase motor. When current is passed through both groups to drive the rotor 40, the rotating machine 10 functions as a six-phase motor.

The resin body 33 is electrically insulating. The resin body 33 adheres closely to the windings 32 to protect and support the windings 32. The resin body 33 is formed in a cylindrical shape that surrounds the rotating shaft 50, following the shape of the stator core 31. Note that the dotted lines in Figure 5 indicate the area where the resin body 33 is located. The outer surface of the resin body 33, which is the stator outer surface 33a (annular outer surface), adheres closely to the inner surface 20a (inner wall surface) of the case 20. The inner surface of the resin body 33, which is the stator inner surface 33b (annular inner surface), adheres closely to the outer surface of the cooling piping 60, which will be described later.

The resin body 33 includes a molded resin body 331 and an adhesive resin body 332 (see Figure 4). The molded resin body 331 molds the windings 32 so as to cover the entire windings 32. The adhesive resin body 332 is applied to the surface of the molded resin body 331. The molded resin body 331 has enough rigidity to support the windings 32.

The adhesive resin body 332 has lower rigidity than the molded resin body 331. The adhesive resin body 332 adheres to the case 20 and the cooling piping 60 in a plastically deformed state. The adhesive resin body 332 is made of a material in which fibrous material is mixed with resin. Specific examples of fibrous material include carbon fiber and aluminum nitride fiber. The surfaces of the case 20 and the cooling piping 60 have fine irregularities formed during the manufacturing process. The adhesive resin body 332 may deform to match these surface irregularities and adhere to them. Heat dissipation fins F10 are provided on the outer peripheral surface 20b (outer wall surface) of the case 20. The axial range A1 in which the heat dissipation fins F10 are provided includes the axial range A2 in which the resin body 33 adheres.

The windings 32 generate heat when current is applied. This heat raises the temperature of the stator 30, and ultimately the rotor 40 and rotating shaft 50. This temperature rise in the rotating machine 10 leads to a decrease in rotational output. In particular, the increased electrical resistance of the windings 32 leads to a decrease in rotational output. Therefore, in this embodiment, the inner surface of the stator 30 is cooled by cooling piping 60, and the outer surface of the stator 30 is cooled by heat dissipation fins F10.

Specifically, some of the heat generated in the windings 32 is thermally conducted through the molded resin body 331, the adhesive resin body 332, and the cooling piping 60, in that order, and is then released into the coolant flowing inside the cooling piping 60. In other words, the stator 30 is liquid-cooled from the inner periphery by the cooling piping 60. In addition, some of the heat generated in the windings 32 is thermally conducted through the molded resin body 331, the adhesive resin body 332, the case 20, and the heat dissipation fins F10, in that order, and is then released into the outside air flowing through the air-cooled duct 90. In other words, the stator 30 is air-cooled from the outer periphery by the heat dissipation fins F10.

As shown in FIG. 1, the inverter device 80 includes a first inverter device 80A and a second inverter device 80B. In FIG. 1, the rotating machine 10 is illustrated as eMOT, the first inverter device 80A as MCUA, and the second inverter device 80B as MCUB. MCU is an abbreviation for Motor Control Unit. The first inverter device 80A converts DC power supplied from the battery into AC and supplies it to the U-phase coil U1, V-phase coil V1, and W-phase coil W1 of the first group. The second inverter device 80B converts DC power supplied from the battery into AC and supplies it to the U-phase coil U2, V-phase coil V2, and W-phase coil W2 of the second group.

The first inverter device 80A and the second inverter device 80B can each operate independently to convert power. In this way, by providing multiple inverter devices for one rotating machine 10, redundancy is provided in the power supply to the rotating machine 10.

Each of the first inverter device 80A and the second inverter device 80B has inverter circuit components, an inverter control unit, and an inverter case. The inverter case houses the inverter circuit components and the inverter control unit. The inverter circuit components include at least switching elements and smoothing capacitors. The switching elements form upper and lower arm circuits, and their on/off operation is controlled by the inverter control unit. The aforementioned heat dissipation fins F80 are provided on the outer surface of the inverter case. Heat generated in the switching elements when current is applied is conducted from the inverter case to the heat dissipation fins F80 and released into the outside air flowing through the air-cooled duct 90. In other words, the inverter circuit components are air-cooled by the heat dissipation fins F80.

The cooler 70 shown in Figure 1 circulates a coolant, which cools the stator 30. The coolant circulates as a liquid without undergoing a phase change. The coolant may be oil or water. If oil is used as the coolant, some of the lubricating oil for the gears in the reducer 4 may be used as the coolant. If water is used as the coolant, antifreeze or anti-rust agents may be added to the water to prevent the water from freezing.

The cooler 70 has a heat exchanger 71, a pump 72, and a reserve tank 73. The heat exchanger 71 has a piping section 71a and heat dissipation fins F70. The piping section 71a is connected to the coolant circulation path and forms a coolant passage therein through which the coolant flows. The heat dissipation fins F70 are provided on the piping section 71a. The heat of the coolant flowing through the coolant passage is transferred to the heat dissipation fins F70 via the piping section 71a and released into the outside air flowing through the air-cooled duct 90. In other words, the coolant, which has received heat from the stator 30 and become hot, is cooled by heat exchange with the outside air by the heat dissipation fins F80.

Pump 72 is located in the coolant circulation path and draws in and discharges the coolant. Reserve tank 73 is located in the coolant circulation path and temporarily stores the circulating coolant. The coolant discharged from pump 72 flows sequentially through supply pipe 63, connection pipe 61, cooling pipe 60, connection pipe 62, discharge pipe 64, the internal passage of heat exchanger 71, and reserve tank 73, before being drawn into pump 72. In other words, the circulation path is formed by pump 72, supply pipe 63, connection pipe 61, cooling pipe 60, connection pipe 62, discharge pipe 64, and heat exchanger 71. The coolant flowing through cooling pipe 60 absorbs heat mainly from stator 30. The coolant flowing through heat exchanger 71 dissipates heat to the outside air through heat dissipation fins F70.

Next, the liquid cooling structure using the cooling pipes 60 will be described in detail. The cooling pipes 60 in this embodiment are made of a non-magnetic material such as resin. However, the cooling pipes 60 may also be made of metal. As shown in Figures 2 and 4, the cooling pipes 60 have passages 60a inside them through which the coolant flows. The passages 60a are arc-shaped and extend circumferentially, and multiple passages 60a are provided. The multiple passages 60a are arranged side by side in the axial direction. The multiple passages 60a are connected to each other so that the coolant supplied from one connection pipe 61 is distributed to the multiple passages 60a. The multiple passages 60a are also connected to each other so that the coolant that has flowed through the passages 60a is collected and discharged from one connection pipe 62.

As shown in Figure 5, the cooling pipe 60 has an arc shape that extends circumferentially along the stator inner surface 33b. The cooling pipe 60 can also be said to have a shape that extends around the axial direction. The cross section of the cooling pipe 60 cut perpendicular to the direction of flow of the coolant is rectangular. The pipe outer surface 60b, which is the outer surface of the cooling pipe 60, is thermally connected to the stator inner surface 33b. In other words, the pipe outer surface 60b is in close contact with the adhesive resin body 332 to ensure sufficient heat conduction from the resin body 33 to the cooling pipe 60.

The axial dimension of the cooling pipe 60 is the same as the axial dimension of the resin body 33. However, as long as the entire pipe outer surface 60b is in close contact with the stator inner surface 33b, the axial dimension of the cooling pipe 60 may be smaller than the axial dimension of the resin body 33. Alternatively, as long as the entire stator inner surface 33b is in close contact with the pipe outer surface 60b, the axial dimension of the resin body 33 may be smaller than the axial dimension of the cooling pipe 60.

As shown in Figures 2 and 5, the inner circumferential surface 60c of the cooling pipe 60 is spaced apart in the radial direction from the fastening portion 52 of the rotating shaft 50 and faces the outer circumferential surface of the fastening portion 52. The inner circumferential surface 60c extends circumferentially along the outer circumferential surface of the fastening portion 52.

The cooling pipe 60 is an arc-shaped pipe that extends axially but is not connected in a ring shape. One end of the arc of the cooling pipe 60 is connected to the connection pipe 61, and the other end of the arc is connected to the connection pipe 62. However, the cooling pipe 60 may be formed in a ring-shaped shape, and a member that separates the passage 60a may be provided between the portion connected to the connection pipe 61 and the portion connected to the connection pipe 62.

One end of the connection pipe 61 is connected to one end of the cooling pipe 60, and the other end of the connection pipe 61 is connected to the supply pipe 63. One end of the connection pipe 62 is connected to the other end of the cooling pipe 60, and the other end of the connection pipe 62 is connected to the discharge pipe 64. In this embodiment, the connection pipes 61 and 62 are made of resin, but they may also be made of metal. The cross section of the connection pipes 61 and 62 taken perpendicular to the flow direction of the cooling liquid has a rectangular shape.

As shown in Figure 6, the stator core 31 of the stator 30 has a main body portion 31a and a flange portion 31b. The main body portion 31a has a shape that extends in the axial direction. A winding 32 is wound around the main body portion 31a. The flange portions 31b are provided on both axial ends of the main body portion 31a. The flange portions 31b are plate-shaped and extend perpendicular to the axial direction from the ends of the main body portion 31a. The flange portions 31b prevent the winding 32 from moving axially and coming off the main body portion 31a. Note that the winding 32 is not shown in Figure 6.

The connection pipes 61, 62 are arranged between the flange portion 31b and the winding 32. The connection pipes 61, 62 are sandwiched axially between the flange portion 31b and the winding 32. In the example shown in FIG. 2, the connection pipes 61, 62 contact the flange portion 31b of the pair that is located on the propeller 2 side in the axial direction. However, the connection pipes 61, 62 may also be arranged so that they contact the flange portion 31b located on the opposite side of the propeller 2. Alternatively, the connection pipes 61, 62 may be arranged so that the connection pipe 61 contacts one of the pair of flange portions 31b, and the connection pipe 62 contacts the other flange portion 31b.

The connection pipes 61, 62 extend radially across the stator 30 and also extend through the case 20. In other words, a portion of the connection pipes 61, 62 is located in the through-hole of the case 20. The connection pipes 61, 62 extend from the inside to the outside of the case 20.

The supply pipes 63 and exhaust pipes 64 are arranged outside the case 20. The supply pipes 63 and exhaust pipes 64 are arranged to extend axially along the outer surface of the case 20. The supply pipes 63 and exhaust pipes 64 are arranged circumferentially between multiple heat dissipation fins F10. In other words, the supply pipes 63 and exhaust pipes 64 are arranged circumferentially together with multiple heat dissipation fins F10. In the example of Figure 5, no heat dissipation fins F10 are arranged circumferentially between the supply pipes 63 and exhaust pipes 64, but heat dissipation fins F10 may be arranged between the supply pipes 63 and exhaust pipes 64.

As described above, according to this embodiment, the rotating machine 10 has a rotor 40 arranged so that an axial gap is provided with respect to the stator 30, and the rotating machine 10 is equipped with a cooling pipe 60. The cooling pipe 60 has a passage 60a therein through which coolant flows. The cooling pipe 60 is thermally connected to the stator inner surface 33b. Therefore, the stator 30 can be cooled with coolant without immersing the stator core 31 or windings 32 in the coolant. Furthermore, the stator 30 can be efficiently cooled from the inside annular region of the stator 30, where heat tends to build up. Therefore, the stator 30 can be sufficiently cooled despite the simple structure.

Here, the rotating shaft 50 is located radially inside the cooling pipe 60. Therefore, if a path for supplying coolant to the cooling pipe 60 were to be secured radially inside the cooling pipe 60, the supply path would become complicated. In consideration of this, the rotating machine 10 of this embodiment is equipped with a connection pipe 61 and a supply pipe 63. The connection pipe 61 is shaped to extend radially from the stator 30. One end of the connection pipe 61 is connected to the cooling pipe 60, and the other end of the connection pipe 61 is located radially outside the stator 30. The supply pipe 63 is connected to the other end of the connection pipe 61 and supplies coolant to the cooling pipe 60 through the connection pipe 61. This allows coolant to be supplied to the cooling pipe 60 from the radially outside of the cooling pipe 60, simplifying the coolant supply path.

Furthermore, in this embodiment, the stator core 31 of the stator 30 has a main body portion 31a that extends axially and around which the windings 32 are wound, and a flange portion 31b provided at the axial end of the main body portion 31a. The connection pipes 61, 62 are arranged between the flange portion 31b and the windings 32. This allows the space between the flange portion 31b and the windings 32 to be effectively used as arrangement space for the connection pipes 61, 62. This effectively prevents the rotating machine 10 from becoming larger in size due to the provision of a coolant supply path. In particular, in this embodiment, the rotor 40 is arranged on both one and the other axial sides of the stator 30. In this case, by adopting the above layout in which the connection pipes 61, 62 are arranged between the flange portion 31b and the windings 32, it is possible to effectively prevent the rotating machine 10 from becoming larger in size in the axial direction due to the provision of a coolant supply path.

Furthermore, in this embodiment, the supply pipe 63 is arranged outside the case 20 and is arranged to extend in the axial direction of the rotor 40 along the outer surface of the case 20. This prevents the supply pipe 63 from interfering with the flow of cooling air in the axial direction along the outer surface of the case 20.

Furthermore, in this embodiment, heat dissipation fins F10 are provided on the outer peripheral surface 20b of the case 20. The inner peripheral surface 20a of the case 20 is thermally connected to the stator outer peripheral surface 33a. As a result, when cooling the stator 30, in addition to liquid cooling from the stator inner peripheral surface 33b, it is also air-cooled from the stator outer peripheral surface 33a. This increases the amount of heat dissipated from the stator 30, improving cooling performance.

Here, if a soft material is used for the resin body 33 that molds the windings 32, the adhesion between the resin body 33 and the cooling piping 60 can be improved, and the performance of cooling the windings 32 can be improved. However, the tradeoff is that the resin body 33 cannot adequately support the windings 32. In consideration of this, the stator 30 of this embodiment has a molded resin body 331 and an adhesive resin body 332. The molded resin body 331 molds the windings 32. The adhesive resin body 332 is a resin body that is more susceptible to plastic deformation than the molded resin body 331. The adhesive resin body 332 is disposed between the molded resin body 331 and the cooling piping 60, and is in close contact with the molded resin body 331 and the cooling piping 60. This allows the molded resin body 331 to adequately support the windings 32, and the adhesive resin body 332 can improve adhesion with the cooling piping 60. This improves the cooling performance of the resin body 33 while still maintaining the function of supporting the winding 32.

Here, because the rotor 40 is located directly above the cooling pipe 60, if the cooling pipe 60 were made of metal, eddy currents would be generated in the cooling pipe 60. As a result, eddy current loss would cause a decrease in output and a rise in temperature. In consideration of this, in this embodiment, the cooling pipe 60 is made of a non-magnetic material such as resin. This prevents the generation of eddy currents as described above, and also prevents a decrease in output and a rise in temperature due to eddy current loss.

Second Embodiment
In the present embodiment shown in Fig. 7, the cooling pipe 60 is configured by combining multiple members. The cooling pipe 60 has a structure in which a first member 601 located on the radially inner side and a second member 602 located on the radially outer side are combined. In this embodiment, the first member 601 and the second member 602 are made of resin, but they may also be made of metal. The first member 601 and the second member 602 are made of different materials.

Because the second member 602 is in close contact with the stator 30, a material with better thermal conductivity than the first member 601 is used for the second member 602. A material with better strength than the second member 602 may be used for the first member 601 to ensure the strength of the cooling piping 60. Alternatively, if the strength of the cooling piping 60 is sufficiently ensured by the second member 602, a material with a lower density than the second member 602 may be used for the first member 601 to achieve weight reduction.

The second member 602 is formed with multiple partition walls 602a. The partition walls 602a extend in an arc shape in the circumferential direction and protrude radially toward the first member 601. The multiple partition walls 602a are arranged side by side in the axial direction. In the example shown in Figure 7, three passages 60a are formed by two partition walls 602a.

The protruding end of the partition wall 602a is spaced apart from the first member 601. In other words, a gap is provided between the protruding end of the partition wall 602a and the first member 601. This avoids the concern that dimensional variations between the first member 601 and the second member 602 may make it impossible to combine the first member 601 and the second member 602. In other words, the gap absorbs the dimensional tolerances between the first member 601 and the second member 602.

(Third embodiment)
While the rotating machine 10 according to the first embodiment has one cooling pipe 60, the rotating machine 10 according to this embodiment has a plurality of cooling pipes 60 as shown in FIG. 8 . The plurality of cooling pipes 60 are arranged side by side in the circumferential direction. The number of cooling pipes 60 is the same as the number of phases of AC power supplied to the rotating machine 10. In this embodiment, assuming that the rotating machine 10 is driven by three-phase AC, three cooling pipes 60 are provided. The three cooling pipes 60 have the same circumferential length. Connection pipes 61 and 62 are connected to each of the three cooling pipes 60.

According to this embodiment, as shown in FIG. 9, the circumferential length of each cooling pipe 60 is shortened. This makes it easier to manufacture the cooling pipes 60 than when manufacturing long, large cooling pipes 60. Furthermore, because the circumferential length of each cooling pipe 60 is shortened, pressure loss can be reduced. Furthermore, because the stator 30 is cooled by multiple cooling pipes 60, uneven cooling can be suppressed, and bias in the temperature distribution of the stator 30 can be suppressed.

(Fourth embodiment)
In the cooling pipe 60 according to the first embodiment, the flow direction of the coolant flowing through the passages 60a is the same for all of the passages 60a. In contrast, in this embodiment, as shown in Fig. 10 , the flow direction of the coolant is different for each of the passages 60a. In the example of Fig. 10 , the coolant supplied from the connection pipe 61 flows into two of the four passages 60a and flows counterclockwise in Fig. 5 . The coolant then flows into the remaining two passages 60a, flows clockwise, and is discharged from the connection pipe 62.

According to this embodiment, uneven cooling of the stator 30 by the cooling pipes 60 can be suppressed, and bias in the temperature distribution of the stator 30 can be suppressed.

Fifth Embodiment
In the present embodiment shown in Fig. 11, the rotating machine 10 includes an outer circumferential cooling pipe 610 in addition to the cooling pipe 60 that is in close contact with the stator inner circumferential surface 33b. The outer circumferential cooling pipe 610 is in close contact with the stator outer circumferential surface 33a. The inner circumferential surface of the outer circumferential cooling pipe 610 is in close contact with the adhesive resin body 332, similar to the cooling pipe 60. The outer circumferential surface of the outer circumferential cooling pipe 610 is in close contact with the inner circumferential surface 20a of the case 20. Furthermore, while three cooling pipes 60 are provided in the third embodiment shown in Fig. 8, two cooling pipes 60 are provided in this embodiment.

Note that the outer circumferential cooling piping 610 according to this embodiment is arranged so as to follow the inner circumferential surface 20a of the case 20. However, the outer circumferential cooling piping 610 may also be arranged so as to follow the outer circumferential surface 20b of the case 20. In this case, the outer circumferential cooling piping 610 is air-cooled by the outside air flowing through the air-cooled duct 90.

In this embodiment, the coolant flowing through the outer circumferential cooling piping 610 dissipates heat from the heat dissipation fins F10 via the case 20. This improves the cooling performance of the stator 30. Alternatively, the heat exchange load on the heat exchanger 71 can be reduced, allowing the heat exchanger 71 to be made smaller. Alternatively, the heat exchanger 71 can be eliminated.

Furthermore, since this embodiment also includes multiple cooling pipes 60, the circumferential length of each cooling pipe 60 is shortened. This makes it easier to manufacture the cooling pipes 60 and reduces pressure loss. Furthermore, since the stator 30 is cooled by multiple cooling pipes 60, uneven cooling can be suppressed, and uneven temperature distribution in the stator 30 can also be suppressed.

Sixth Embodiment
In the fifth embodiment, the cooling water flows in opposite directions in the two cooling pipes 60. That is, the cooling water flows clockwise in one cooling pipe 60 in FIG. 11 , and counterclockwise in the other cooling pipe 60. In contrast, in the present embodiment, as shown in FIG. 12 , the cooling water flows in the same direction in the two cooling pipes 60. That is, the cooling water flows clockwise in one cooling pipe 60 in FIG. 12 , and also clockwise in the other cooling pipe 60. This can help suppress uneven temperature distribution in the stator 30.

Seventh Embodiment
As shown in Fig. 13, the inverter device 80 according to this embodiment includes an inverter circuit 810 and an inverter case 820. The inverter circuit 810 includes a plurality of switching elements constituting upper and lower arm circuits, a smoothing capacitor, and the like. The inverter case 820 houses the inverter circuit 810. The inverter case 820 has an annular shape with an annular inner circumferential surface 821 and an annular outer circumferential surface 822 extending axially. The outer circumferential surface 822 is provided with heat dissipation fins F80.

As shown in FIG. 14, the inner circumferential surface 821 forms an inverter passage 821a. The inverter passage 821a is a passage that allows outside air blown by the air-cooling fan 5 to pass through the inside of the inverter unit 80. The inverter passage 821a is also called a through-outside air passage. An inverter passage 821a is provided in each of the first inverter unit 80A and the second inverter unit 80B. The inverter passage 821a is formed coaxially with the rotation center line C. The inverter passage 821a has a shape that extends linearly along the axis.

An inlet 823a for the inverter passage 821a is formed on the upper surface 823 of the inverter case of the first inverter unit 80A. An outlet 824a for the inverter passage 821a is formed on the lower surface 824 of the inverter case of the second inverter unit 80B. The upper surface 823 of the inverter case faces the lower surface of the case 20 of the rotating machine 10. A gap passage 823b is formed between the upper surface 823 and the lower surface of the case 20.

The outside air that passes through the heat dissipation fins F10 branches off into a passage between the air-cooled duct 90 and the outer peripheral surface 822 and a gap passage 823b. The outside air that flows into the gap passage 823b flows into the inverter passage 821a through the inlet 823a and into the heat exchanger 71 through the outlet 824a. An upper fin F81, separate from the heat dissipation fins F80 mentioned above, is provided on the top surface 823. Therefore, heat from the inverter case 820 is dissipated not only from the heat dissipation fins F80 but also from the upper fins F81.

The piping section 71a of the heat exchanger 71 according to this embodiment extends in a ring shape around the outlet 824a. As shown by the arrows in FIG. 14, the cooling water in the piping section 71a flows in a circumferential direction around the rotation center line C. In addition to the heat dissipation fins F70 described above, the piping section 71a is equipped with inner fins F71, which are heat dissipation fins. The heat dissipation fins F70 are provided on the outer ring side of the piping section 71a. The inner fins F71 are provided on the inner ring side of the piping section 71a.

The annular inner peripheral surface of the piping section 71a forms the heat exchanger passage 71b. The heat exchanger passage 71b is a passage through which the outside air flowing out from the outlet 824a of the inverter passage 821a exchanges heat with the inner fins F71. The heat exchanger passage 71b is formed coaxially with the rotation center line C. The heat exchanger passage 71b has a shape that extends linearly along the axis. The inlet of the heat exchanger passage 71b is positioned opposite the outlet 824a of the inverter passage 821a.

The dashed dotted line in Figure 14 indicates the area where the outlet 824a is projected in the axial direction. In the example of Figure 14, the entire outlet 824a faces the heat exchanger passage 71b, but only a portion of the outlet 824a may face the heat exchanger passage 71b. Also, in the example of Figure 14, the entire projected area of the outlet 824a is included in the heat exchanger passage 71b, but only a portion of the projected area may be included in the heat exchanger passage 71b, or the entire inlet of the heat exchanger passage 71b may be included in the above projected area.

As described above, the EPU 3 serving as an electric unit according to this embodiment includes a rotating machine 10 (motor device), an inverter device 80, and a heat exchanger 71. The heat exchanger 71 has a piping section 71a and inner fins F71. The piping section 71a defines a coolant passage therein that is connected to the circulation path. The inner fins F71 are heat dissipation fins that are provided on the piping section 71a and exchange heat with outside air. The rotating machine 10, inverter device 80, and heat exchanger 71 are aligned in the direction of the rotation axis. The inverter device 80 is provided with a through-flow outside air passage 821a that allows outside air to pass through and circulate inside the device. The inner fins F71 are positioned opposite the outlet 824a of the through-flow outside air passage 821a.

However, if the heat exchanger 71 is to be mounted on the EPU 3 as in this embodiment, the placement of the intake path that guides outside air to the heat exchanger 71 becomes an issue. In other words, if the intake path is located in a position contrary to this embodiment, it will result in an increase in the size of the entire EPU 3. To address this issue, in this embodiment, the outside air is guided to the heat exchanger 71 using the inverter passage 821a that passes through the inverter device 80. Therefore, it is possible to mount the heat exchanger 71 on the EPU 3 while preventing the EPU 3 from becoming larger.

Furthermore, in this embodiment, the piping section 71a has a shape that extends in an annular shape around the outlet 824a. The inner fin F71 is provided on the annular inner side of the piping section 71a. This helps to prevent the EPU 3 from becoming too large.

Eighth Embodiment
In this embodiment shown in Figures 15 and 16, the heat exchanger 71 is modified from that of the seventh embodiment. In the heat exchanger 71 according to this embodiment, a plurality of heat dissipation fins F72 and piping sections 71a are arranged alternately in a predetermined direction. This predetermined direction is the left-right direction in Figure 15 and also the left-right direction in Figure 16. The piping sections 71a extend in a direction perpendicular to the predetermined direction and the axial direction, that is, in the up-down direction in Figure 16.

One end of the multiple pipe sections 71a is connected to inflow tank 71d. The other end of the multiple pipe sections 71a is connected to outflow tank 71c. The coolant discharged from pump 72 flows into inflow tank 71d and is then distributed to the multiple pipe sections 71a. The coolant that has flowed through the multiple pipe sections 71a is then collected in outflow tank 71c and circulated through the circulation path by pump 72. Note that inflow tank 71d and outflow tank 71c are not shown in Figure 16.

The heat dissipation fins F72 have a corrugated shape as shown in Figure 16. Multiple piping sections 71a are arranged in a predetermined direction at predetermined intervals. Multiple heat exchanger passages 71b, through which outside air circulates, are formed between adjacent piping sections 71a. A heat dissipation fin F72 is arranged in each heat exchanger passage 71b. The heat dissipation fins F72 are in contact with the outer surface of the piping section 71a.

A portion of the inlet of the heat exchanger passage 71b is positioned opposite the outlet 824a of the inverter passage 821a. The dashed dotted line in Figure 16 indicates the area where the outlet 824a is projected in the axial direction. In the example of Figure 16, the entire outlet 824a faces the heat exchanger passage 71b, but only a portion of the outlet 824a may face the heat exchanger passage 71b.

As described above, in this embodiment, as in the seventh embodiment, the inverter device 80 is provided with a through-flow outside air passage 821a. The heat dissipation fins F72 are arranged opposite the outlet 824a of the through-flow outside air passage 821a. This makes it possible to mount the heat exchanger 71 on the EPU 3 while preventing the EPU 3 from becoming larger.

Furthermore, in this embodiment, the heat dissipation fins F72 and piping sections 71a are arranged alternately in a predetermined direction. The heat dissipation fins F72 arranged in the predetermined direction are arranged opposite the outlet 824a. This helps to prevent the EPU 3 from becoming larger.

(Other embodiments)
The rotating machine 10 according to each of the above embodiments is a double axial gap motor in which two rotors 40 are provided for one stator 30. In contrast, the rotating machine 10 may have a structure in which one rotor 40 is provided for one stator 30, or a structure in which one rotor 40 is provided for two stators 30. Furthermore, although the rotor 40 described above generates a field magnet with the magnet 41, the rotor 40 may have a structure in which a field winding is provided instead of the magnet 41.

The rotating machine 10 is not limited to being used to power the propeller of an aircraft, but may also be used to power the running of a vehicle, or as a stationary motor or generator, etc.

In each of the above embodiments, the exhaust pipe 64 and the supply pipe 63 are arranged outside the case 20. Alternatively, at least one of the exhaust pipe 64 and the supply pipe 63 may be arranged inside the case 20, and the connection pipe 61 may be eliminated. In each of the above embodiments, the exhaust pipe 64 and the supply pipe 63 extend in the axial direction. Alternatively, a portion of the exhaust pipe 64 and the supply pipe 63 may extend diagonally or perpendicularly to the axial direction.

In each of the above embodiments, the connection pipes 61, 62 are arranged between the flange portion 31b and the winding 32. However, the connection pipes 61, 62 may also be arranged on the opposite side of the flange portion 31b from the winding 32.

In each of the above embodiments, heat dissipation fins F10 are provided to exchange heat with the air flowing outside the case. In other words, the rotating machine 10 is liquid-cooled from the inside and air-cooled from the outside, and is cooled by both liquid and air. However, the rotating machine 10 may also be liquid-cooled from the outside. Furthermore, the heat dissipation fins F10 may be eliminated and the outside of the outer rotating machine 10 may be air-cooled.

In the seventh and eighth embodiments described above, the through-flow outside air passage includes the inverter passage 821a. Alternatively, the rotating machine 10 may have a motor passage formed inside the case 20 that allows outside air to pass through. The motor passage may also be included in the through-flow outside air passage. Furthermore, at least one of the inverter passage 821a and the motor passage may be included in the through-flow outside air passage.

In the seventh and eighth embodiments described above, the heat exchanger 71 is arranged downstream of the outside air flow in the through-passage. Alternatively, the heat exchanger 71 may be arranged upstream of the through-passage. In this case, the air-cooled fan 5 functions to draw air into the air-cooled duct 90. That is, the inlet 90a of the air-cooled duct 90 functions as an outlet, and the outlet 90b functions as an inlet. Furthermore, the inlet 823a of the inverter passage 821a functions as an outlet, and the outlet 824a functions as an inlet. In this case, the inlet of the through-passage of the outside air faces the inner fins F71 and the heat dissipation fins F72.

Although the present disclosure has been described with reference to examples, it is understood that the present disclosure is not limited to those examples or structures. The present disclosure also encompasses various modifications and modifications within the scope of equivalents. In addition, while various combinations and forms are shown in the present disclosure, other combinations and forms including only one element, more, or less are also within the scope and spirit of the present disclosure.

(Disclosure of technical ideas)
This specification discloses multiple technical ideas described in the following multiple clauses. Some clauses may be described in a multiple dependent form, with the subsequent clause alternatively referring to the preceding clause. Furthermore, some clauses may be described in a multiple dependent form, referring to another multiple dependent clause. These multiple dependent clauses define multiple technical ideas.

(Technical thought 1)
an annular stator (30) that generates a rotating magnetic field;
a rotor (40) arranged to provide an axial gap with respect to the stator;
a cooling pipe (60) that is thermally connected to the annular inner peripheral surface (33b) of the stator and has a passage (60a) therein through which a cooling liquid flows.

(Technical thought 2)
a connecting pipe (61) extending in the radial direction of the stator, one end of which is connected to the cooling pipe and the other end of which is located radially outside the stator;
a supply pipe (63) connected to the other end and supplying a coolant to the cooling pipe through the connection pipe.

(Technical thought 3)
The stator has a stator core (31) and a winding (32) wound around the stator core,
The stator core has a main body portion (31 a) extending in the axial direction of the rotor and around which the winding is wound, and a flange portion (31 b) provided at an axial end of the main body portion,
The rotating machine according to Technical Concept 2, wherein the connection pipe is disposed between the flange portion and the winding.

(Technical thought 4)
The rotating machine according to Technical Idea 2 or 3, wherein the supply pipe is arranged outside a case (20) that houses the stator and the rotor inside, and is arranged to extend in the axial direction of the rotor along the outer surface of the case.

(Technical Thought 5)
a case (20) for accommodating the stator and the rotor therein;
The outer wall surface (20b) of the case is provided with a heat dissipation fin (F10) for exchanging heat with the air flowing outside the case,
The rotating machine according to any one of Technical Ideas 1 to 4, wherein an annular outer peripheral surface (33a) of the stator is thermally connected to an inner wall surface (20a) of the case.

(Technical Thought 6)
The rotating machine according to any one of Technical Ideas 1 to 5, wherein the rotor is disposed on both one side and the other side of the stator in the axial direction.

(Technical Thought 7)
The stator includes:
a molded resin body (331) for molding the winding (32);
A rotating machine according to any one of technical ideas 1 to 6, having an adhesive resin body (332) that is more easily plastically deformed than the molded resin body, that is disposed between the molded resin body and the cooling piping, and that is in close contact with the molded resin body and the cooling piping.

(Technical philosophy A1)
a motor device (10) that rotates;
an inverter device (80) that converts DC power into AC power and supplies the AC power to the motor device;
a heat exchanger (71) provided in a circulation path of a coolant that cools at least one of the motor device and the inverter device, and that exchanges heat between the coolant and outside air;
Equipped with
The heat exchanger includes a piping portion (71a) that defines a coolant passage therein and is connected to the circulation path, and a heat dissipation fin (F71) that is provided in the piping portion and exchanges heat with outside air,
the motor device, the inverter device, and the heat exchanger are arranged to be aligned in a direction of a rotation axis of the motor device,
At least one of the motor device and the inverter device is provided with a through-air passage (821a) for allowing outside air to pass through the device interior,
The heat dissipation fin is disposed opposite an inlet (823a) or an outlet (824a) of the through-passage of the outside air.

(Technical philosophy A2)
the piping portion has a shape extending in an annular shape around the inlet or the outlet,
The electric unit according to Technical Idea A1, wherein the heat dissipation fins are provided on the annular inner side of the piping portion.

(Technical philosophy A3)
a plurality of the heat dissipation fins and the plurality of the piping portions are arranged alternately in a predetermined direction;
The electric unit according to Technical Idea A1, wherein the plurality of heat dissipation fins arranged in the predetermined direction are arranged opposite the inlet or the outlet.

(Technical philosophy A4)
The inverter device includes an inverter circuit (810) and an inverter case (820) that houses the inverter circuit therein,
The inverter case has a shape having an annular inner peripheral surface (821) and an annular outer peripheral surface (822) extending around the rotation axis direction,
The inner circumferential surface forms an inverter passage (821a) through which outside air passes to the inverter device,
The electric unit according to any one of technical ideas A1 to A3, wherein the through outside air passage includes the inverter passage.

One objective of technical concepts A1 to A4 is to provide an electric unit that can be fitted with a heat exchanger while minimizing its size.

Claims (7)

an annular stator (30) that generates a rotating magnetic field;
a rotor (40) arranged to provide an axial gap with respect to the stator;
a cooling pipe (60) that is thermally connected to the annular inner peripheral surface (33b) of the stator and has a passage (60a) therein through which a cooling liquid flows. a connecting pipe (61) extending in the radial direction of the stator, one end of which is connected to the cooling pipe and the other end of which is located radially outside the stator;
a supply pipe (63) connected to the other end of the cooling pipe and supplying a coolant to the cooling pipe through the connecting pipe, the rotating machine according to claim 1 . The stator has a stator core (31) and a winding (32) wound around the stator core,
The stator core has a main body portion (31 a) extending in the axial direction of the rotor and around which the winding is wound, and a flange portion (31 b) provided at an axial end of the main body portion,
The rotating machine according to claim 2 , wherein the connecting pipe is disposed between the flange portion and the winding. A rotating machine as described in claim 2 or 3, wherein the supply pipe is arranged outside a case (20) that houses the stator and the rotor, and extends in the axial direction of the rotor along the outer surface of the case. a case (20) for accommodating the stator and the rotor therein;
The outer wall surface (20b) of the case is provided with a heat dissipation fin (F10) for exchanging heat with the air flowing outside the case,
4. The rotating machine according to claim 1, wherein an annular outer peripheral surface (33a) of the stator is thermally connected to an inner wall surface (20a) of the case. A rotating machine according to any one of claims 1 to 3, wherein the rotor is disposed on both one and the other axial sides of the stator. The stator includes:
a molded resin body (331) for molding the winding (32);
4. The rotating machine according to claim 1, further comprising: an adhesive resin body (332) that is more easily plastically deformed than the molded resin body, that is disposed between the molded resin body and the cooling piping, and that is in close contact with the molded resin body and the cooling piping.