Drive devices and electrical devices

Abstract

To efficiently cool all heat-generating components in a drive device having multiple heat-generating components. [Solution] The drive device 16 has a rotating shaft 34 and drives the rotating shaft. The drive device 16 has a cooling passage P formed on the outer circumference of the drive device 16 and extending along the axial direction X of the rotating shaft 34, and a plurality of heat-generating parts 46 arranged adjacent to the cooling passage P. The plurality of heat-generating parts 46 include a first heat-generating part 46A and a second heat-generating part 46B arranged at a distance from the first heat-generating part 46A in the axial direction X. The plurality of heat-generating parts 46 are arranged such that, when viewed in the axial direction X, the centers 44C of each of the plurality of heat-generating parts 46 do not overlap with each other.

Description

Technical Field

[0001] The present invention relates to a drive device having a rotating shaft and driving the rotating shaft, and an electric device.

Background Art

[0002] In recent years, efforts to achieve a low-carbon society or a decarbonized society have been active, and research and development on electrification technologies have been conducted in vehicles, aircraft, etc. in order to reduce CO2 emissions and improve energy efficiency.

[0003] There is a technology for cooling a drive device having a plurality of heat generating parts and a rotating shaft and driving the rotating shaft. For example, the drive device described in FIGS. 13 to 15 of Patent Document 1 includes two motors that rotate a rotating shaft, two inverters that supply power to the motors, and a fan that generates an air flow for cooling the two motors and the two inverters. The stator of the motor includes a coil. The coil generates heat when energized. The switch module of the inverter also generates heat when energized. In Patent Document 1, the stator of the motor and the switch module of the inverter correspond to the heat generating parts. In the drive device of Patent Document 1, the fan, two adjacent motors, and two adjacent inverters are arranged along the axial direction of the rotating shaft. And this drive device has a motor housing that houses two motors and an inverter housing that houses two inverters.

[0004] On the outer peripheral surface of the motor housing, plate-like fins protruding in the radial direction are provided corresponding to the two motors respectively. The air flow generated by the fan flows axially along the outer peripheral surface of the motor housing, whereby the two motors are cooled. Also, on the outer peripheral surface of the inverter housing, plate-like fins protruding in the radial direction are provided corresponding to the two inverters respectively. The air flow generated by the fan flows axially along the outer peripheral surface of the inverter housing, whereby the two inverters are cooled.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2023-163874 [Overview of the project] [Problems that the invention aims to solve]

[0006] Incidentally, in the drive device described in Figures 13 to 15 of Patent Document 1, two motors and two inverters are arranged in a row along the axial direction of the airflow. As a result, the airflow that is heated by cooling the fins corresponding to the upstream motor cools the fins corresponding to the downstream motor, reducing the cooling efficiency of the heat-generating part (stator) of the downstream motor. Furthermore, the airflow that is heated by cooling the fins corresponding to the upstream inverter cools the fins corresponding to the downstream inverter, reducing the cooling efficiency of the heat-generating part (switch module) of the downstream inverter.

[0007] In view of the above background, the present invention aims to efficiently cool all heat-generating components in a drive device having multiple heat-generating components. This will ultimately contribute to improving energy efficiency. [Means for solving the problem]

[0008] To solve the above problems, one aspect of the present invention provides a drive device (16) having a rotating shaft (34) and driving the rotating shaft, comprising: a cooling passage (P) formed on the outer circumference and extending along the axial direction (X) of the rotating shaft; and a plurality of heat-generating parts (46) arranged adjacent to the cooling passage, wherein the plurality of heat-generating parts include a first heat-generating part (46A) and a second heat-generating part (46B) arranged at a distance from the first heat-generating part in the axial direction, and arranged such that the centers of each of the plurality of heat-generating parts do not overlap when viewed in the axial direction.

[0009] In this embodiment, the refrigerant flows along the cooling passage in the axial direction. Furthermore, the centers of the multiple heat-generating components are arranged so that they do not overlap with each other when viewed in the axial direction. This prevents the refrigerant, having received heat from one heat-generating component, from flowing toward the centers of other heat-generating components. As a result, the cooling of other heat-generating components by the refrigerant that has received heat from one heat-generating component is suppressed. Therefore, the drive device (electrical device) can efficiently cool all heat-generating components.

[0010] In the above embodiment, each of the plurality of heating elements includes a plurality of heating elements (56A, 56B, 57A, 57B), and the plurality of heating elements may be arranged at equal intervals in the circumferential direction when viewed in the axial direction.

[0011] In this embodiment, each heat-generating section includes multiple heat-generating elements. Furthermore, when viewed in the axial direction, all heat-generating sections are arranged at equal intervals in the circumferential direction. This prevents all heat-generating elements in all heat-generating sections from becoming densely packed when viewed in the axial direction. As a result, all heat-generating elements can be cooled efficiently.

[0012] In the above embodiment, the drive device further comprises a plurality of electric motors that drive the rotating shaft, and a plurality of control devices that are energized and generate heat to control the operation of the electric motors, wherein the plurality of heat-generating units may be a plurality of the control devices.

[0013] According to this embodiment, the drive device can be reliably and efficiently cooled.

[0014] In the above embodiment, the plurality of heating elements include a plurality of first heating elements aligned with each other in the axial direction, and a plurality of second heating elements spaced apart from the plurality of first heating elements in the axial direction and aligned with each other in the axial direction, wherein the plurality of first heating elements may be arranged at equal intervals in the circumferential direction, and the plurality of second heating elements may be arranged at equal intervals in the circumferential direction.

[0015] In this embodiment, the multiple first heating elements are arranged at equal intervals in the circumferential direction. This prevents heat from one first heating element from being transferred to another. Therefore, all first heating elements can be cooled efficiently. Furthermore, the multiple second heating elements are arranged at equal intervals in the circumferential direction. This prevents heat from one second heating element from being transferred to another. Therefore, all second heating elements can be cooled efficiently. As a result, all first and second heating elements can be cooled efficiently.

[0016] In the above embodiment, the multiple heating elements may be arranged so as not to overlap each other when viewed in the axial direction.

[0017] In this embodiment, when viewed in the axial direction, each of the multiple heat-generating components is arranged so as not to overlap with one another. The refrigerant flows along the axial direction through the cooling passage. This prevents the refrigerant that has received heat from one heat-generating component from flowing toward other heat-generating components. As a result, the cooling of other heat-generating components by the refrigerant that has received heat from one heat-generating component is suppressed. Therefore, the drive device can efficiently cool all heat-generating components.

[0018] In the above embodiment, the cooling passage has a heat-receiving region (HA) adjacent to the heat-generating portion and a non-heat-receiving region (CA) circumferentially adjacent to the heat-receiving region, and each of the heat-receiving regions may be provided with a plurality of heat dissipation fins (45, 45A, 45B, 45C).

[0019] According to this embodiment, the heat dissipation fins promote the cooling of heat-generating parts adjacent to the heat-receiving area, so that all heat-generating parts can be cooled efficiently.

[0020] In the above embodiment, a plurality of heat dissipation fins are provided in each of the heat-receiving region and the non-heat-receiving region, and the density of the heat dissipation fins in the heat-receiving region may be greater than the density of the heat dissipation fins in the non-heat-receiving region.

[0021] According to this aspect, since the heat dissipation fins promote the cooling of the heat generating portion adjacent to the heat receiving region, all the heat generating portions can be efficiently cooled.

[0022] In the above aspect, the plurality of heat dissipation fins may include a plurality of rectifying fins (45A) that extend to the outside in the radial direction of the drive device and continuously extend in the axial direction from one end to the other end in the axial direction of the drive device.

[0023] According to this aspect, the rectifying fins continuously extend in the axial direction from one end to the other end in the axial direction of the drive device. As a result, in the cooling passage, the flow of the refrigerant across the rectifying fins in a direction intersecting the axial direction is suppressed. Therefore, in the cooling passage, the refrigerant flowing between two adjacent rectifying fins flows along the axial direction between the two adjacent rectifying fins. Thereby, the refrigerant that has received the heat of one heat generating portion is suppressed from flowing in a direction intersecting the axial direction and flowing toward another heat generating portion. That is, the refrigerant that has received the heat of the heat generating portion is suppressed from cooling another heat generating portion on the downstream side. Thereby, all the heat generating portions can be efficiently cooled.

[0024] In the above aspect, in the heat receiving region, at least one auxiliary fin (45B) having a length in the axial direction shorter than the length in the axial direction of the rectifying fin may be provided between two adjacent rectifying fins.

[0025] According to this aspect, since the auxiliary fins promote the cooling of the heat generating portion adjacent to the heat receiving region, all the heat generating portions can be efficiently cooled.

[0026] In the above aspect, it may have a propeller (35) fixed to the rotating shaft and generating a propelling wind flowing in the direction in which the refrigerant flows in the cooling passage.

[0027] According to this aspect, since a part of the propelling wind F flows into the cooling passage, all the heat generating portions can be efficiently cooled.

[0028] To solve the above problems, one aspect of the present invention provides an electrical device (16) comprising a cooling passage (P) formed on the outer periphery and extending along a first direction (X), and a plurality of heat-generating parts (46) arranged adjacent to the cooling passage, wherein the plurality of heat-generating parts include a first heat-generating part (46A) and a second heat-generating part (46B) spaced apart from the first heat-generating part in the first direction, and arranged such that the centers of each of the plurality of heat-generating parts do not overlap when viewed in the first direction.

[0029] In this embodiment, the refrigerant flows through the cooling passage along a first direction. Furthermore, when viewed in the first direction, the centers of the multiple heat-generating components are arranged so as not to overlap with each other. This prevents the refrigerant, which has received heat from one heat-generating component, from flowing toward the centers of other heat-generating components. As a result, the cooling of other heat-generating components by the refrigerant that has received heat from one heat-generating component is suppressed. Therefore, the electrical device can efficiently cool all heat-generating components. [Effects of the Invention]

[0030] According to the above embodiment, in a drive device having multiple heat-generating parts, all heat-generating parts can be efficiently cooled. [Brief explanation of the drawing]

[0031] [Figure 1] Perspective view showing an aircraft according to the first embodiment. [Figure 2] A schematic partial cross-sectional view showing the propulsion unit according to the first embodiment. [Figure 3] schematic cross-sectional view of the drive device according to the first embodiment. [Figure 4] Overall circuit diagram of the electric motor and control device according to the first embodiment [Figure 5] Circuit diagram showing the configuration of the control device according to the first embodiment. [Figure 6] Perspective view of the housing and control device according to the first embodiment [Figure 7] Section VII-VII in Figure 3 [Figure 8] Figure 3, section VIII-VIII [Figure 9] Developed view of the outer periphery of the housing according to the first embodiment. [Figure 10] Cross-sectional view of the housing according to the second embodiment [Figure 11] Developed view of the housing according to the second embodiment [Figure 12] Developed view of the housing according to the third embodiment [Modes for carrying out the invention]

[0032] <<First Embodiment>> <Aircraft 1> Hereinafter, an aircraft 1 according to a first embodiment of the present invention will be described with reference to the drawings. In the drawings and the following description, front, back, left, right, up, and down are directions defined with respect to the aircraft 1.

[0033] Figure 1 is a perspective view showing an aircraft 1 according to the first embodiment. The aircraft 1 is an electric vertical take-off and landing (eVTOL) aircraft capable of taking off and landing vertically. The aircraft 1 has a fuselage 2 extending in the longitudinal direction, a forewing 3 extending in the lateral direction and connected to the front of the fuselage 2, a rearwing 4 extending in the lateral direction and connected to the rear of the fuselage 2, a left arm 5L extending in the longitudinal direction and connecting the left end of the forewing 3 and the left side of the rearwing 4, and a right arm 5R extending in the longitudinal direction and connecting the right end of the forewing 3 and the right side of the rearwing 4.

[0034] The front of the fuselage 2 is provided with a cabin (not shown) for the crew. The rear end of the fuselage 2 is provided with left and right propulsion units 7 (details described later) for generating forward thrust for the aircraft 1.

[0035] The left arm 5L and the right arm 5R are each provided with a plurality (for example, four) of lifting units 10 spaced apart in the front-rear direction to generate upward and downward forces for the aircraft 1. Each lifting unit 10 has a lifting drive device 12 and a lifting propeller 13 attached to the lifting drive device 12. The lifting drive device 12 has an electric motor (not shown) and is configured to rotate the lifting propeller 13 by the driving force of this electric motor.

[0036] <Propulsion Unit 7> Figure 2 is a schematic cross-sectional view of a propulsion unit 7. Each propulsion unit 7 has a support 15 and a drive device 16 supported by the support 15.

[0037] The support 15 is fixed to the rear end of the fuselage 2 (see Figure 1). The support 15 has a cylindrical nacelle 20 extending in the front-rear direction and front and rear mounting frames 21 fixed to the inner circumferential surface of the nacelle 20. Each mounting frame 21 has an annular hub 22 provided concentrically with the nacelle 20 and a plurality of spokes 23 extending radially from the outer circumferential surface of the hub 22 and connected to the inner circumferential surface of the nacelle 20.

[0038] <Drive device 16> As shown in Figure 2, the drive unit 16 comprises a first drive unit 31, a second drive unit 32, a fan 33, a shaft 34 (rotating axis) extending in the front-rear direction and rotatably supported by the drive unit 16, and a propeller 35 fixed to the rear of the shaft 34. The drive unit 16 is housed in the nacelle 20. The drive unit 16 is fixed to the hubs 22 of the front and rear mounting frames 21. The drive unit 16 drives the shaft 34. The drive unit 16 is one example of an electrical device.

[0039] The first drive unit 31 and the second drive unit 32 each support the shaft 34 so as to be rotatable around its axis, and rotate the shaft 34. The first drive unit 31 is fixed to the hub 22 of the front mount frame 21. The second drive unit 32 is fixed to the hub 22 of the rear mount frame 21.

[0040] Fan 33 generates cooling air W to cool the first drive unit 31 and the second drive unit 32. The cooling air W flows towards the rear.

[0041] The shaft 34 extends along its axial direction X (first direction). A conical front cover 36, which widens towards the rear, is fixed to the first end 34A (front end) of the shaft 34 on the first drive unit 31 side. The front cover 36 is positioned behind the center of the propeller 35. A conical rear cover 37, which widens towards the front, is fixed to the second end 34B (rear end) of the shaft 34 on the second drive unit 32 side.

[0042] The propeller 35 is configured to rotate integrally with the shaft 34 as the shaft 34 rotates, thereby generating a propulsive airflow F (see Figure 3) that flows along the axial direction X (rearward). The propeller 35 generates a forward thrust force for the aircraft 1 by generating the propulsive airflow F.

[0043] <First drive unit 31, second drive unit 32> As shown in Figure 2, each of the first drive unit 31 and the second drive unit 32 includes a housing 41, a pair of front and rear covers (not shown) attached to the front and rear of the housing 41, a duct 42, an electric motor 43, and two control devices 44.

[0044] Figure 3 is a schematic cross-sectional view of the drive device 16. As shown in Figure 3, the housing 41 is formed in a cylindrical shape extending in the front-rear direction on the outer circumference of the shaft 34. The outer surface of the housing 41 is provided with a plurality of heat dissipation fins 45 (see Figure 6) that extend radially outward from the drive device 16 and along the axial direction X. Each heat dissipation fin 45 is formed integrally with the housing 41.

[0045] A pair of front and rear covers (not shown) are formed in a disc shape. The pair of front and rear covers are positioned at the front and rear of the housing 41, closing the front and rear openings of the housing 41. The covers and the housing 41 are joined by known methods. The joining of the covers and the housing 41 may be done by fastening with bolts and nuts, by riveting, by adhesive bonding, by welding, or by a combination of these methods.

[0046] The duct 42 covers the outer circumference of the housing 41 and is formed in a cylindrical shape extending along the axial direction X. The duct 42 of the first drive unit 31 and the duct 42 of the second drive unit 32 are integrally formed and extend to the outer circumference of the fan 33. The duct 42 is attached to the housing 41 by known methods. For example, the cover may have a projection extending radially outward, to which the duct 42 is fixed. Alternatively, the housing 41 may have a projection extending radially outward from its outer circumference, to which the duct 42 is fixed. Bolts and nuts may be used to fix the projection of the cover to the duct 42, or the projection of the housing 41 to the duct 42, rivets may be used, adhesives may be used, welding may be used, or a combination of these may be used.

[0047] A cooling passage P is formed between the outer circumferential surface of the housing 41 and the duct 42, extending continuously in the front-to-rear direction from the front end to the rear end of the housing 41. The cooling passage P extends both circumferentially and along the axial direction X of the shaft 34. Air (refrigerant) flows through the cooling passage P.

[0048] When the fan 33 rotates, the cooling air W flows backward along the axial direction X (in the direction in which the propulsion air F generated by the propeller 35 flows). The cooling air W flows into the cooling passage P and flows backward along the axial direction X through the cooling passage P. The electric motor 43 and the control device 44 are positioned adjacent to the cooling passage P, and the heat generated from the electric motor 43 and the heat generated from the control device 44 is transferred to the cooling passage P. The heat generated from the electric motor 43 and the heat generated from the control device 44 is cooled by the cooling passage P.

[0049] The electric motor 43 has a stator 43A and a rotor 43B, and is connected to a control device 44. The electric motor 43 is an inner-rotor type three-phase AC motor. The stator 43A is fixed inside the housing 41 and is formed in a cylindrical shape. The rotor 43B is located inside the stator 43A, facing the stator 43A at a distance, and is formed integrally with the shaft 34. The stator 43A has multiple coils (not shown), and the rotor 43B has multiple permanent magnets (not shown) fixed to its outer circumference. The magnetic force of the multiple coils of the stator 43A and the magnetic force of the permanent magnets of the rotor 43B generate a rotational force that rotates the rotor 43B around the axis of the shaft 34. The rotor 43B rotates together with the shaft 34. As a result, the electric motor 43 drives the shaft 34. In the stator 43A, the multiple coils generate heat. The stator 43A is located adjacent to the cooling passage P.

[0050] The control device 44 has a case (not shown) and an inverter housed inside the case. As will be described later, the control device 44 is connected to the electric motor 43 and controls the operation of the electric motor 43. Each of the first drive unit 31 and the second drive unit 32 has two control devices 44. The control device 44 is located adjacent to the cooling passage P. The control device 44 is energized and generates heat in order to control the operation of the electric motor 43. The control device 44 is a heat-generating section 46. The heat-generating section 46 is a device in the drive device 16 that generates particularly strong heat.

[0051] The control device 44 is attached to the housing 41 in a known manner in front of the electric motor 43. The control device 44 may be attached to the housing 41 by fastening with bolts and nuts, by rivets, by adhesive, by welding, or by a combination of these methods.

[0052] Figure 4 is an overall circuit diagram of the electric motor 43 and control device 44 for driving the electric motor 43. As shown in Figure 4, in each of the first drive unit 31 and the second drive unit 32, two control devices 44 and two capacitors 52 are connected to a DC power supply 51 located outside the drive device 16 via a DC input connector 53. The DC power supply 51 may be a battery such as a primary or secondary battery, or it may be a generator. The DC input connector 53 is provided with the positive and negative terminals of the DC power supply 51.

[0053] The two control devices 44 and the two capacitors 52 are connected in parallel to the positive and negative terminals of the DC power supply 51. Each of the two control devices 44 is connected to the AC output terminals 54A to 54C of the electric motor 43. Each control device 44 includes an inverter that converts the direct current input from the DC power supply 51 into alternating current. The capacitors 52 smooth the direct current input from the DC power supply 51 to the control device 44.

[0054] Figure 5 is a circuit diagram showing the configuration of the control device 44. As shown in Figure 5, the control device 44 has power modules 55A to 55C. Power modules 55A to 55C are connected in parallel to the positive and negative terminals of the DC power supply 51 via DC input connectors 53. Each of the power modules 55A to 55C is connected to the respective AC output terminals 54A to 54C of the electric motor 43.

[0055] Each of the three power modules 55A to 55C has switching elements 56A and 56B and freewheeling diodes 57A and 57B. Switching element 56A and freewheeling diode 57A are connected in parallel to the positive terminal of the DC power supply 51 and one of the AC output terminals 54A to 54C of the electric motor 43. Switching element 56B and freewheeling diode 57B are connected in parallel to the negative terminal of the DC power supply 51 and one of the AC output terminals 54A to 54C of the electric motor 43.

[0056] Thus, the control device 44 has power modules 55A to 55C. Each of the power modules 55A to 55C has switching elements 56A and 56B and freewheeling diodes 57A and 57B. Therefore, the control device 44 has six switching elements (three switching elements 56A and three switching elements 56B) and six freewheeling diodes (three freewheeling diodes 57A and three freewheeling diodes 57B). The switching elements 56A and 56B are semiconductor elements such as IGBTs and MOSFETs. These switching elements 56A and 56B and the freewheeling diodes 57A and 57B typically generate more heat than the capacitor 52. The switching elements 56A and 56B and the freewheeling diodes 57A and 57B are elements that generate relatively strong heat and are referred to as "heat-generating elements". Note that elements other than switching elements and freewheeling diodes may also be referred to as "heat-generating elements".

[0057] Furthermore, the control device 44 is a heating unit 46 having 12 (or more) heating elements (switching elements 56A, 56B, and freewheeling diodes 57A, 57B). There is no limit to the number of heating elements that the heating unit (control device 44) may have. The heating unit (control device 44) does not have to have 6 switching elements (3 switching elements 56A and 3 switching elements 56B) and 6 freewheeling diodes (3 freewheeling diodes 57A and 3 freewheeling diodes 57B).

[0058] Capacitor 52 is connected in parallel with power modules 55A to 55C to the DC power supply unit 51. Capacitor 52 smooths the DC current input from the DC power supply unit 51 to power modules 55A to 55C (control device 44). Capacitor 52 protects power modules 55A to 55C by smoothing the pulse current (pulsating current caused by surge voltage) generated in the DC current input from the DC power supply unit 51 to power modules 55A to 55C. Note that capacitor 52 may also be a capacitor unit consisting of multiple capacitors connected in parallel.

[0059] Figure 6 is a perspective view of the housing 41 and the control device 44. The two control devices 44 of the first drive unit 31 are referred to as the "first heating section 46A," and the two control devices 44 of the second drive unit 32 are referred to as the "second heating section 46B." The drive device 16 has two first heating sections 46A and two second heating sections 46B that are spaced apart from the two first heating sections 46A in the axial direction X. "Heating section 46" is a collective term for the first heating section 46A and the second heating section 46B. The first heating section 46A and the second heating section 46B have a plurality of heating elements (switching elements 56A, 56B, freewheeling diodes 57A, 57B).

[0060] Figure 7 is a cross-sectional view of the first drive unit 31 taken along line VII-VII of Figure 3. The two first heat-generating parts 46A of the first drive unit 31 are arranged at equal intervals in the circumferential direction. A weak heat region 41A, located between the two first heat-generating parts 46A in the circumferential direction, contains components such as capacitors 52 (referred to as the "weak heat region") that generate less heat than the heat-generating parts 46. This arrangement of the two first heat-generating parts 46A and the two weak heat regions 41A allows the axial length X of the first drive unit 31 to be shortened.

[0061] Figure 8 is a cross-sectional view of the second drive unit 32 taken along line VIII-VIII of Figure 3. The two second heat-generating parts 46B of the second drive unit 32 are arranged at equal intervals in the circumferential direction. A weak heat-generating part such as a capacitor 52 is arranged in the weak heat region 41B between the two second heat-generating parts 46B in the circumferential direction. This arrangement of the two second heat-generating parts 46B and the two weak heat regions 41B makes it possible to shorten the axial length X of the second drive unit 32.

[0062] As shown in Figures 6 to 8, the first drive unit 31 and the second drive unit 32 are offset from each other by 90 degrees in the circumferential direction. The drive device 16 has four control devices 44 (heating units 46). Viewed in the axial direction X, these four control devices 44 are arranged at equal intervals in the circumferential direction. Therefore, viewed in the axial direction X, the centers 44C (shown as 44C (uppercase) in the figures) of the four control devices 44 are arranged so as not to overlap each other. Also, viewed in the axial direction X, the four control devices 44 are arranged so as not to overlap each other.

[0063] Figure 9 is an unfolded view of the outer periphery of the housing 41. In the cooling passage P, the region adjacent to the heat-generating unit 46 (control device 44) is called the "heat-receiving region HA," and the region adjacent to the heat-receiving region HA in the circumferential direction, other than the heat-receiving region HA, is called the "non-heat-receiving region CA." The heat-receiving region HA is the region that requires more cooling than the non-heat-receiving region CA. Heat dissipation fins 45 are provided in the heat-receiving region HA and the non-heat-receiving region CA. The heat-receiving region HA may also be the region surrounded by the outline of the heat-generating unit 46 (control device 44) projected radially outward onto the outer circumferential surface of the housing 41. The non-heat-receiving region CA may be a region located in the circumferential direction of the heat-receiving region HA and not included in the heat-receiving region HA.

[0064] The housing 41 is provided with a heat dissipation fin 45, which consists of a plurality of rectifier fins 45A and a plurality of auxiliary fins 45B placed between two adjacent rectifier fins 45A. There are no restrictions on the number of rectifier fins 45A or auxiliary fins 45B.

[0065] As shown in Figure 6, each of the multiple rectifier fins 45A extends radially outward from the housing 41 of the first drive unit 31 and the second drive unit 32, and is formed as a plate that extends continuously in the axial direction X from one end to the other of the drive device 16. The radial outer end of each rectifier fin 45A abuts against the duct 42. In this embodiment, the portion of the rectifier fin 45A provided on the first drive unit 31 and the portion provided on the second drive unit 32 are adjacent to each other so as to be continuous. These two portions may abut each other. These two portions may be formed integrally. The multiple rectifier fins 45A are provided at equal intervals in the circumferential direction of the housing 41.

[0066] Each of the multiple auxiliary fins 45B extends radially outward from the housing 41 of the first drive unit 31 or the second drive unit 32, and is formed as a plate that extends continuously in the axial direction X from one end to the other of the housing 41. As shown in Figure 9, the axial length X of the auxiliary fins 45B is half the axial length X of the rectifier fins 45A, and is shorter than the axial length X of the rectifier fins 45A. In addition, the radial outer ends of each of the rectifier fins 45A are in contact with the duct 42.

[0067] As shown in Figure 9, the rectifier fins 45A are provided in the heat-receiving region HA and the non-heat-receiving region CA. On the other hand, the auxiliary fins 45B are provided in the heat-receiving region HA. In other words, the heat-receiving region HA is provided with both the rectifier fins 45A and the auxiliary fins 45B. On the other hand, the non-heat-receiving region CA is provided with the rectifier fins 45A, but not the auxiliary fins 45B. In the non-heat-receiving region CA, there are no auxiliary fins 45B that pass through the weak heat regions 41A and 41B. As a result, the density of heat dissipation fins 45 in the heat-receiving region HA is higher than the density of heat dissipation fins 45 in the non-heat-receiving region CA. Here, density refers to the density of the number of heat dissipation fins 45 per unit area.

[0068] As shown in Figure 3, the cooling air W generated by the rotation of the fan 33 flows into the cooling passage P. The cooling air W flows backward along the axial direction X in the cooling passage P (in the direction in which the propulsion air F generated by the propeller 35 flows). That is, in Figure 9, the cooling air W flows from left to right.

[0069] Next, the effects of the drive device 16 will be explained.

[0070] Air flows through the cooling passage P along the axial direction X. As shown in Figures 7 to 9, the centers 44C of the four heat-generating parts 46 are arranged so as not to overlap with each other when viewed in the axial direction X. This prevents air that has received heat from the heat-generating parts 46 of the first drive unit 31 from flowing toward the centers 44C of the other heat-generating parts 46 of the second drive unit 32. As a result, the cooling of other heat-generating parts 46 by air that has received heat from one heat-generating part 46 is suppressed. Therefore, the drive device 16 (electrical device) can efficiently cool all of the heat-generating parts 46. Consequently, the drive device 16 can be cooled efficiently.

[0071] As shown in Figure 5, each heat-generating unit 46 (control device 44) includes 12 heat-generating elements (switching elements 56A, 56B, and freewheeling diodes 57A, 57B). As shown in Figures 6 and 9, all heat-generating units 46 are arranged at equal intervals in the circumferential direction when viewed in the axial direction X. This prevents all heat-generating elements of all heat-generating units 46 from being densely packed when viewed in the axial direction X. As a result, all heat-generating elements can be cooled efficiently.

[0072] The heat-generating section 46 (first heat-generating section 46A, second heat-generating section 46B) is a control device 44 that is energized and generates heat to control the operation of the electric motor 43. This ensures that the drive device 16 can be cooled reliably and efficiently.

[0073] The two first heat-generating elements 46A are arranged at equal intervals in the circumferential direction. This prevents heat from one first heat-generating element 46A from transferring to the other. Therefore, all first heat-generating elements 46A can be cooled efficiently. Similarly, the two second heat-generating elements 46B are arranged at equal intervals in the circumferential direction. This prevents heat from one second heat-generating element 46B from transferring to the other. Therefore, all second heat-generating elements 46B can be cooled efficiently. As a result, all first heat-generating elements 46A and second heat-generating elements 46B can be cooled efficiently.

[0074] Viewed in the axial direction X, each of the four heat-generating components 46 is arranged so as not to overlap with one another. Air flows through the cooling passage P along the axial direction X. This prevents air that has received heat from the heat-generating components 46 of the first drive unit 31 from flowing toward the other heat-generating components 46 of the second drive unit 32. As a result, the cooling of other heat-generating components 46 by air that has received heat from one heat-generating component 46 is suppressed. Therefore, the drive device 16 (electrical device) can efficiently cool all of the heat-generating components 46. Consequently, the drive device 16 can be cooled efficiently.

[0075] Each heat-receiving region HA is provided with multiple heat dissipation fins 45. This allows the heat dissipation fins 45 to promote the cooling of the heat-generating parts 46 adjacent to the heat-receiving region HA, thereby enabling efficient cooling of all heat-generating parts 46.

[0076] The density of heat dissipation fins 45 in the heat-receiving region HA is greater than the density of heat dissipation fins 45 in the non-heat-receiving region CA. As a result, the heat dissipation fins 45 promote the cooling of the heat-generating parts 46 adjacent to the heat-receiving region HA, so that all heat-generating parts 46 can be cooled efficiently.

[0077] Multiple rectifier fins 45A are provided. The rectifier fins 45A extend continuously in the axial direction X from one end to the other of the drive device 16. As a result, in the cooling passage P, the flow of air across the rectifier fins 45A and in a direction intersecting the axial direction X is suppressed. Therefore, in the cooling passage P, the air flowing between two adjacent rectifier fins 45A flows along the axial direction X between the two adjacent rectifier fins 45A. This suppresses the air that has received heat from the heat-generating part 46 of the first drive unit 31 from flowing in a direction intersecting the axial direction X and flowing toward other heat-generating parts 46 of the second drive unit 32. In other words, the air that has received heat from the heat-generating part 46 is suppressed from cooling other heat-generating parts 46 downstream. As a result, all heat-generating parts 46 can be cooled efficiently.

[0078] In the heat receiving region HA, an auxiliary fin 45B is provided between two adjacent rectifier fins 45A. This allows the auxiliary fin 45B to promote the cooling of the heat-generating section 46 adjacent to the heat receiving region HA, thereby enabling efficient cooling of all heat-generating sections 46.

[0079] Furthermore, the auxiliary fins 45B cause pressure loss. Within the cooling passage P, air attempts to bypass areas with high pressure loss. The rectifier fins 45A extend radially outward and are formed as plates that continuously extend in the axial direction X from one end to the other of the drive device 16. This prevents air from flowing across the rectifier fins 45A in a direction intersecting the axial direction X. Air flowing between two adjacent rectifier fins 45A flows along the axial direction X between them. This prevents air flowing through the cooling passage P from bypassing the auxiliary fins 45B. As a result, a sufficient amount of air can be secured to flow through the heat receiving region HA. Therefore, all heat-generating parts 46 can be cooled efficiently.

[0080] The propulsion air F generated by the propeller 35 flows in the direction of airflow (rearward) in the cooling passage P (see Figure 3). As a result, a portion of the propulsion air F flows into the cooling passage P, allowing all heat-generating parts 46 to be cooled efficiently.

[0081] <<Second Embodiment>> Figure 10 is a cross-sectional view of the housing 41 of the first drive unit 31 according to the second embodiment. Figure 10 corresponds to the cross-sectional view of Figure 7 of the first embodiment. As shown in Figure 10, the drive device 16 of the second embodiment is provided with a plurality of heat dissipation fins 45C that pass through the heat receiving region HA, and no auxiliary fins 45B are provided. In the following descriptions of the second and third embodiments, the same or similar components are denoted by the same reference numerals, and redundant detailed descriptions are omitted.

[0082] Figure 11 is an exploded view of the housing 41 according to the second embodiment. As shown in Figures 10 and 11, each heat dissipation fin 45C extends radially outward from the housing 41 of the first drive unit 31 or the second drive unit 32 and is formed as a plate that extends continuously in the axial direction X from one end to the other of the housing 41. Heat dissipation fins 45C that pass through the heat receiving region HA are provided for all heat receiving regions HA. The heat dissipation fins 45C can promote the cooling of heat-generating parts 46 adjacent to the heat receiving region HA. As a result, all heat-generating parts 46 can be cooled efficiently.

[0083] <<Third Embodiment>> Figure 12 is an exploded view of the housing 41 according to the third embodiment. The drive device 16 of the third embodiment has a plurality of heat dissipation fins 45D provided between two adjacent rectifier fins 45A and not passing through the heat receiving region HA. Each heat dissipation fin 45D extends radially outward from the housing 41 of the first drive unit 31 or the second drive unit 32 and is formed as a plate that extends continuously in the axial direction X from one end to the other of the housing 41 in the axial direction X. In the first embodiment, one auxiliary fin 45B is provided between two adjacent rectifier fins 45A. In this embodiment, however, two auxiliary fins 45B and one heat dissipation fin 45D are provided between two adjacent rectifier fins 45A.

[0084] Between two adjacent rectifier fins 45A, the number of auxiliary fins 45B is greater than the number of heat dissipation fins 45D. Therefore, the density of heat dissipation fins 45 in the heat-receiving region HA is higher than the density of heat dissipation fins 45 in the non-heat-receiving region CA. As a result, the heat-generating parts 46 adjacent to the heat-receiving region HA can be cooled efficiently, and thus all heat-generating parts 46 can be cooled efficiently.

[0085] This concludes the description of the embodiments, but the present invention is not limited to the above embodiments and can be broadly modified and implemented. For example, the drive device 16 does not have to include a propeller 35. The propeller 35 is configured to rotate integrally with the shaft 34 as the shaft 34 rotates, thereby generating a propulsive airflow F (see Figure 3) that flows along the axial direction X (rearward), but the direction of the propulsive airflow F is not limited to the rear. For example, the propeller 35 may be configured to generate a propulsive airflow that flows along the front. Furthermore, there are no restrictions on the orientation of the drive device 16.

[0086] In the first to third embodiments, air was used as the refrigerant, but any fluid refrigerant is acceptable. The refrigerant may be a gas or a liquid. Also, the electric motor 43 does not have to be an inner rotor type three-phase AC motor. The housing 41 and duct 42 are formed in a cylindrical shape. The shape of the housing 41 may be a polygonal cylinder such as a hexagonal cylinder. Similarly, the shape of the duct 42 may be a polygonal cylinder such as a hexagonal cylinder.

[0087] In the first to third embodiments, the control device 44 was made into a heat-generating unit 46. The device corresponding to the heat-generating unit may be changed. The three power modules (power modules 55A to 55C) of the control device 44 may be made into a heat-generating unit. In this case, the three power modules (power modules 55A to 55C) may be arranged at equal intervals in the circumferential direction. Also, in this case, the first drive unit 31 and the second drive unit 32 of the drive device 16 in the first to third embodiments may each have only one control device 44. Furthermore, there is no limit to the number of control devices 44 that the first drive unit 31 and the second drive unit 32 may have. For example, the first drive unit 31 may have three or more control devices 44. Also, the second drive unit 32 may have three or more control devices 44.

[0088] The rectifier fins 45A, auxiliary fins 45B, heat dissipation fins 45C and 45D are formed in a plate shape extending in the axial direction X. These heat dissipation fins 45 are optional. Also, heat dissipation fins with a different shape from these heat dissipation fins 45 may be provided. The heat dissipation fins only need to be shaped to extend radially outward from the housing 41. For example, cylindrical heat dissipation fins, prismatic heat dissipation fins, conical heat dissipation fins, or pyramidal heat dissipation fins extending radially outward from the housing 41 may be provided. [Explanation of symbols]

[0089] 16: Drive unit 34: Shaft (rotating axis) 35: Propeller 44: Control device 44C: Center 45: Heat dissipation fins 45A: Rectifying fins 45B: Auxiliary fins 45C: Heat dissipation fins 45D: Heat dissipation fins 46: Heat-generating part 46A: First heating element 46B: Second heating element CA: Non-heat receiving area F: Propulsion wind HA:Heat receiving area P: Cooling passage X: Axial direction

Claims

1. A drive device having a rotating shaft and driving the rotating shaft, A cooling passage formed on the outer circumference and extending along the axial direction of the rotation axis, It has a plurality of heat-generating parts arranged adjacent to the cooling passage, The plurality of heating elements include a first heating element and a second heating element arranged at an axial distance from the first heating element. A drive device in which, when viewed in the axial direction, the multiple heat-generating parts are arranged such that their centers do not overlap with each other.

2. The drive device according to claim 1, wherein each of the plurality of heating units includes a plurality of heating elements, and the plurality of heating units are arranged at equal intervals in the circumferential direction when viewed in the axial direction.

3. The system further comprises a plurality of electric motors that drive the rotating shaft, and a plurality of control devices that are energized and generate heat to control the operation of the electric motors, The drive device according to claim 1, wherein the plurality of heat-generating units include a plurality of control devices.

4. The plurality of heating elements include a plurality of first heating elements and a plurality of second heating elements arranged at intervals in the axial direction from the plurality of first heating elements. Multiple first heating elements are arranged at equal intervals in the circumferential direction. The drive device according to claim 1, wherein the plurality of second heating elements are arranged at equal intervals in the circumferential direction.

5. The drive device according to claim 1, wherein, when viewed in the axial direction, each of the multiple heat-generating parts is arranged so as not to overlap with one another.

6. The cooling passage has a heat-receiving region adjacent to the heat-generating portion and a non-heat-receiving region adjacent to the heat-receiving region in the circumferential direction. The drive device according to any one of claims 1 to 5, wherein each of the heat receiving regions is provided with a plurality of heat dissipation fins.

7. Multiple heat dissipation fins are provided in each of the heat-receiving region and the non-heat-receiving region. The drive device according to claim 6, wherein the density of the heat dissipation fins in the heat receiving region is greater than the density of the heat dissipation fins in the non-heat receiving region.

8. The drive device according to claim 6, wherein the plurality of heat dissipation fins extend radially outward from the drive device and include a plurality of flow straightening fins that extend continuously in the axial direction from one end to the other end of the drive device in the axial direction.

9. The drive device according to claim 8, wherein in the heat receiving region, at least one auxiliary fin is provided between two adjacent rectifier fins, the auxiliary fin having a length in the axial direction shorter than the axial length of the rectifier fin.

10. The drive device according to any one of claims 1 to 5, further comprising a propeller fixed to the rotating shaft and generating a propulsive airflow that flows in the direction in which the refrigerant flows through the cooling passage.

11. An electrical device, A cooling passage formed on the outer periphery and extending along the first direction, It has a plurality of heat-generating parts arranged adjacent to the cooling passage, The plurality of heating elements include a first heating element and a second heating element arranged at a distance from the first heating element in the first direction. An electrical device in which, when viewed in the first direction, the centers of the multiple heating elements are arranged so as not to overlap with each other.

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