Drive device

Abstract

The drive device includes: a motor including a motor shaft; the first gear rotates by taking the central shaft of the motor shaft as the center; and an inverter including a plurality of structural elements for controlling the motor, at least a portion of the inverter overlapping the motor in the central axis direction, and at least a portion of the inverter being capable of overlapping the first gear in the radial direction of the first gear.

Description

TECHNICAL FIELD

[0001] The technology disclosed in this specification relates to a drive device. BACKGROUND

[0002] (CROSS-REFERENCE TO RELATED APPLICATIONS)

[0003] This application is a related application of Japanese Patent Application No. 2023-45413 filed on March 22, 2023, and claims priority based on the Japanese Patent Application. The entire contents of the Japanese Patent Application are incorporated into the content of this specification.

[0004] Japanese Patent Application Publication No. 2020-40578 discloses a drive device unit that includes a motor and a motor control device that controls the motor. The motor control device is disposed above the motor. SUMMARY

[0005] There are many components in a vehicle that should be mounted in limited mounting space. It is required to effectively utilize the mounting space.

[0006] In this specification, a technology capable of effectively utilizing space is provided.

[0007] A first aspect disclosed in this specification relates to a drive device. The drive device includes a motor including a motor shaft, a first gear that rotates around a center axis of the motor shaft, and an inverter including a plurality of structural elements for controlling the motor, at least a portion of the inverter overlaps with the motor in a direction of the center axis, and at least a portion of the inverter overlaps with the first gear in a radial direction of the first gear.

[0008] In this configuration, a space around the motor shaft generated due to a size difference between the motor and the first gear is configured with the inverter. Thereby, the space around the motor shaft can be effectively utilized.

[0009] Details and further improvements of the technology disclosed in this specification will be described in the “DETAILED DESCRIPTION” below. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 A side view of an electric vehicle that mounts the drive device of the mounting example.

[0011] Figure 2 A side view of the drive device after the housing is removed.

[0012] Figure 3 A schematic internal configuration view of the drive device.

[0013] Figure 4 A plan view of the drive device.

[0014] Figure 5 FIG. 6 is a bottom view of the drive device.

[0015] Figure 6 FIG. 7 is a side view of the drive device for explaining the structure of the bus bar unit.

[0016] Figure 7 FIG. 8 is a perspective view of the bus bar unit.

[0017] Figure 8 FIG. 9 is a perspective view of the bus bar unit.

[0018] Figure 9 FIG. 10 is a structure diagram of the cooling circuit. DETAILED DESCRIPTION

[0019] In the second aspect disclosed in the present specification, in the first aspect, the plurality of structural elements can include a power module including a plurality of switching elements, a smoothing capacitor, and a noise filter, and the power module, the smoothing capacitor, and the noise filter can be arranged in this order from the upper side to the lower side.

[0020] According to this structure, by arranging the battery near the lower end of the inverter, it is possible to shorten the wiring in the case where the power from the battery is supplied to the noise filter, the smoothing capacitor, and the power module in this order.

[0021] In the third aspect disclosed in the present specification, in the second aspect, in each of the power module, the smoothing capacitor, and the noise filter, the length in the rotation direction of the first gear can be longer than the length in the radial direction of the first gear, and a range from an end portion of the power module on the side opposite to the smoothing capacitor to an end portion of the noise filter on the side opposite to the smoothing capacitor in the rotation direction of the first gear can be 180° or more around the center axis.

[0022] In this structure, the long side direction of each of the power module, the smoothing capacitor, and the noise filter is arranged in the rotation direction of the first gear. Thus, it is possible to efficiently use the space around the first gear.

[0023] In the fourth aspect disclosed in the present specification, in the second or third aspect, a second gear can be further included, the second gear can be engaged with the first gear, and the first gear can be arranged between the second gear and the power module.

[0024] The power module is a relatively large structural element among the plurality of structural elements included in the inverter. By arranging the power module across the first gear on the side opposite to the second gear, it is possible to efficiently arrange the power module and the second gear.

[0025] In the fifth aspect disclosed in the present specification, in the fourth aspect described above, the second gear can be disposed at a position lower than the first gear and the power module.

[0026] In this configuration, torque of the motor is transmitted downward from the first gear toward the second gear. According to this configuration, the motor can be disposed at a position above the drive shaft. Thus, the power module and the second gear are efficiently disposed, and the position of the motor with respect to the drive shaft is not greatly changed.

[0027] In the sixth aspect disclosed in the present specification, in any one of the first to fifth aspects described above, a plurality of shafts including the motor shaft and the drive shaft, and one or more gears each disposed on the plurality of shafts can be provided, and the one or more gears disposed on the motor shaft can include the first gear.

[0028] According to this configuration, torque of the motor can be transmitted to the drive shaft via a plurality of gears.

[0029] In the seventh aspect disclosed in the present specification, in the sixth aspect described above, the first gear can have the smallest outer diameter among the one or more gears.

[0030] According to this configuration, among the plurality of gears from the motor to the axle, the plurality of structural elements of the inverter are disposed around the smallest first gear, and thus the space can be efficiently utilized.

[0031] (Embodiment)

[0032] Figure 1 A schematic view showing a front portion of an electric vehicle 2 on which a drive device 10 of the embodiment is mounted is shown from a side. The electric vehicle 2 is provided with a vehicle body 4, a battery pack 6, a suspension beam 8, and a pair of front wheels 100 in addition to the drive device 10. In addition, although not shown, the electric vehicle 2 is also mounted with a pair of rear wheels, a control device, and a plurality of devices for the operation of the electric vehicle 2. For ease of understanding, the outer diameter shape of each part is simplified and shown in the drawing. Figure 1 In FIG. 1, the configuration other than the drive device 10 and the suspension beam 8 is shown in a dashed line. Further, for ease of observation of the drawing, the outer diameter shape of each part is simplified. The electric vehicle 2 includes a hybrid vehicle, a fuel cell vehicle, and the like, in addition to the electric vehicle, in which at least a part of the travel uses an electric motor. Hereinafter, “up”, “down”, “left”, “right”, “front”, and “rear” are described based on the coordinate system in the drawing.

[0033] (Configuration of drive device)

[0034] The drive unit 10 is located forward of the front seats (not shown) of the electric vehicle 2. The drive unit 10 is positioned in a compartment forward of the passenger space of the electric vehicle 2. The drive unit 10 is positioned between a pair of front wheels 100 located at either end of the electric vehicle 2 in the left-right direction. The drive unit 10 is located rearward of the front trunk 9 located near the front of the electric vehicle 2. The front trunk 9 is separated from the passenger space and is a space for carrying luggage. The drive unit 10 is positioned forward of the vehicle center C in the front-rear direction of the electric vehicle 2.

[0035] The drive unit 10 is fixed to the suspension beam 8. The suspension beam 8 is part of a suspension unit (not shown), which includes springs, shock absorbers, etc., respectively disposed on a pair of front wheels 100. The suspension beam 8 holds the springs, shock absorbers, etc. Thus, the suspension unit is mounted on the electric vehicle 2.

[0036] The drive unit 10 is protected by the housing 12. Figure 2 This is a right-side view of the interior of housing 12 with the right side wall of housing 12 removed. In addition to housing 12, drive unit 10 also includes motor 14, gear unit 30, inverter 20 and drive shaft 90.

[0037] The housing 12 houses the motor 14, gear unit 30, inverter 20, and drive shaft 90. The housing 12 defines a housing space for assembling multiple components.

[0038] In the drive unit 10, the inverter 20 converts the direct current from the battery pack 6 into alternating current suitable for the drive motor 14. The battery pack 6 is located below the floor (not shown) of the electric vehicle 2. The battery pack 6 supplies power to the drive unit 10. Thus, the drive unit 10 drives the pair of front wheels 100. In addition, the drive unit 10 functions as a generator. The battery pack 6 stores the power supplied from the drive unit 10.

[0039] Inverter 20 supplies alternating current (AC) to motor 14. Motor 14 is driven by the AC power from inverter 20. The torque of motor 14 is transmitted to drive shaft 90 via gear unit 30. Drive shaft 90 transmits the torque of motor 14 to each of a pair of front wheels 100, thereby rotating the pair of front wheels 100. This drives electric vehicle 2. Inverter 20 converts the AC power generated by motor 14 into direct current (DC) power and supplies it to battery pack 6.

[0040] The motor 14 is located at the top and rear of the drive unit 10. Figure 3 This shows the internal structure of the drive unit 10 as viewed from a perspective looking from the lower front towards the upper rear. Additionally, in Figure 3In the present embodiment, in order to describe the gear unit 30, a part of the structure of the inverter 20 is omitted. The motor 14 has a main body 14a having a rotor 14c and a stator 14d, and a motor shaft 14b extending from the rotor 14c. The stator 14d has a cylindrical shape. Although illustration is omitted, the stator 14d has a stator core having a plurality of teeth and coils arranged to the plurality of teeth. The rotor 14c is arranged to the inner periphery of the stator 14d. The outer peripheral surface of the rotor 14c opposes the inner peripheral surface of the stator 14d. The rotor 14c has a plurality of permanent magnets arranged to the outer peripheral surface of the rotor 14c so that the polarity is alternately switched in the circumferential direction. When alternating current supplied from the inverter 20 is supplied to each coil of the stator 14d, the magnetic field generated in the stator 14d changes. Thereby, the rotor 14c rotates. The motor shaft 14b is arranged coaxially with the center of rotation of the rotor 14c. The motor shaft 14b extends linearly from the main body 14a to the right side.

[0041] (Structure of Gear Unit)

[0042] The torque generated by the driving of the motor 14 is transmitted to the gear unit 30 via the motor shaft 14b. The gear unit 30 has a pinion gear 32, a counter gear 34, a counter gear 42, a ring gear 50, a differential gear 52, and a shaft 44. The pinion gear 32, the counter gear 34, the counter gear 42, and the ring gear 50 each have a cylindrical shape having a plurality of teeth arranged to the outer peripheral surface. The teeth of the pinion gear 32, the counter gear 34, the counter gear 42, and the ring gear 50 are each omitted from illustration. The pinion gear 32 is mounted to the motor shaft 14b. The motor shaft 14b is rotatably supported to the housing 12 by bearings 36, 38 mounted to the housing 12. In the drive device 10, the gear unit 30 directly interfaces with the motor 14, and thus the gear unit 30 and the motor 14 can be easily mechanically connected.

[0043] The counter gear 34 engages with the pinion gear 32 and rotates with the rotation of the pinion gear 32. The counter gear 34 is arranged below and in front of the pinion gear 32. The counter gear 34 is mounted to the shaft 44. The shaft 44 is arranged in parallel with the motor shaft 14b. The shaft 44 is arranged at a position below and in front of the motor shaft 14b. The shaft 44 is rotatably supported to the housing 12 by bearings 46, 48 mounted to the housing 12. The counter gear 42 is mounted to the shaft 44. Thereby, the counter gear 42 is coupled to the counter gear 34 coaxially. The counter gear 42 rotates with the rotation of the counter gear 34. The ring gear 50 engages with the counter gear 42 and rotates with the rotation of the counter gear 42.

[0044] The ring gear 50 is arranged below and in front of the counter gear 42. The ring gear 50 has a center axis Y (refer to FIG. 2) in parallel with the motor shaft 14b. The ring gear 50 is arranged at a position below and in front of the counter gear 42. The ring gear 50 is rotatably supported to the housing 12 by bearings 54, 56 mounted to the housing 12. Figure 2The differential gear 52 rotates around the central axis Y. The gear ring 50 is mounted on the differential gear 52. The differential gear 52 rotates as the gear ring 50 rotates. The differential gear 52 is a gear mechanism that causes the pair of front wheels 100 to rotate independently through the rotation of the gear ring 50. The differential gear 52 is located below and in front of the gear ring 50. The differential gear 52 drives the drive shaft 90. The drive shaft 90 is located below and in front of the shaft 44. When the rotation of the motor 14 is transmitted to the drive shaft 90, the drive shaft 90 rotates around the central axis Y, and the pair of front wheels 100 rotate around the drive shaft 90. Thus, the electric vehicle 2 moves.

[0045] As described above, the countershaft gear 34 is positioned in front of and below the shaft gear 32. The countershaft gear 42 and countershaft gear 34 are coaxially arranged, i.e., aligned in the left-right direction. The gear ring 50 is positioned in front of and below the countershaft gear 42. The differential gear 52 is positioned below and in front of the gear ring 50. In other words, the differential gear 52, via the gear ring 50, countershaft gear 42, and countershaft gear 34, is arranged rearward and upward from the shaft gear 32. Therefore, as... Figure 1 As shown, in the housing 12 that houses the gear unit 30, the upper surface 12a and the lower surface 12b are inclined upwards from the front to the rear, i.e., from the center C of the vehicle.

[0046] The central shaft X of the motor shaft 14b (i.e., the central shaft X of the shaft gear 32) and the central shaft Y of the gear ring 50 are arranged in parallel. For example... Figure 2 As shown, most of the countershaft gear 34 is located below the plane P, which connects the central axis X of the motor shaft 14b and the central axis Y of the gear ring 50. The countershaft gear 42 is located entirely below plane P. In a modified example, the countershaft gear 34 may be located entirely below plane P. With this structure, space can be provided above the gear unit 30. Therefore, devices such as the inverter 20 can be configured above the gear unit 30.

[0047] The outer diameter of the counterspindle gear 34 (i.e., the diameter of the circle connecting the tips of the multiple teeth arranged along the outer circumference of the gear) is larger than the outer diameter of the shaft gear 32. The outer diameter of the gear ring 50 is larger than the outer diameter of the counterspindle gear 42. Therefore, the rotational speed of the shaft gear 32 is reduced in two stages. Among the multiple gears 32, 34, 42, and 50 arranged in the gear unit 30, the outer diameter of the shaft gear 32 is the smallest. Furthermore, in a modified example, the gear unit 30 may be equipped with gears that are the same as or smaller than the shaft gear 32.

[0048] (Inverter structure)

[0049] like Figure 1As shown, the inverter 20 is connected to the battery pack 6 through the power supply line 7. The inverter 20 is a device for converting direct current of the battery pack 6 into alternating current suitable for driving the motor 14. The inverter 20 is a high-voltage component that applies high voltage. Here, "high voltage" means an operating voltage of direct current exceeding 60 V and 1,500 V or less, or an operating voltage of alternating current exceeding 30 V (effective value) and 1,000 V (effective value) or less. The inverter 20 is a device for converting alternating current from the motor 14 into direct current suitable for the battery pack 6. In addition, in a modified example, the inverter 20 can convert direct current into alternating current, but cannot convert alternating current back into direct current.

[0050] As shown, the inverter 20 has a power module 22, a smoothing capacitor 24, a noise filter 26, a connector 28, and bus bar units 60, 70 (see Figure 2 ). Electric power supplied from the battery pack 6 to the inverter 20 is input from the connector 28, passes through the noise filter 26, the bus bar unit 60, the smoothing capacitor 24, the noise filter 26, and the bus bar unit 70 in this order, and is supplied from the bus bar unit 70 to the motor 14. Figure 6

[0051] The connector 28 has terminals (omitted from illustration) connected to terminals of the power supply line 7 and a cover 28a that surrounds the terminals. The connector 28 extends through the housing 12 from the outside to the inside of the housing 12. The terminals extend in the left-right direction and are connected to the power supply line 7. As shown, the cover 28a protrudes downward and rearward from the lower surface 12b of the housing 12. The cover 28a is disposed in a space below the lower surface 12b. The cover 28a is disposed at a position lower than the rear end of the housing 12 and rearward of the lowermost end. Figure 2

[0052] The terminals of the connector 28 extend to the noise filter 26. The noise filter 26 is an electromagnetic compatibility (i.e., EMC (Electro Magnetic Compatibility)) noise filter. The noise filter 26 has circuit-configuration components (omitted from illustration) such as a capacitor and a choke coil, and a housing 26a that houses the circuit-configuration components. The noise filter 26 is housed in the housing 12. The housing 26a is attached to the inner wall of the housing 12. The noise filter 26 is disposed forward and upward of the connector 28.

[0053] The noise filter 26 is connected to the smoothing capacitor 24 via the bus bar unit 60. The smoothing capacitor 24 has a capacitor (omitted from illustration) that absorbs voltage fluctuations and a housing 24a that houses the capacitor. The smoothing capacitor 24 is housed in the housing 12. The housing 24a is attached to the inner wall of the housing 12. The smoothing capacitor 24 is disposed upward of the noise filter 26.

[0054] ​​The smoothing capacitor 24 is connected to the power module 22 via wiring. The power module 22 converts the DC power from the battery pack 6 into AC power. The power module 22 supplies the converted AC power to the motor 14. The power module 22 is equipped with multiple combinations of switching elements (not shown) and diodes (not shown) for converting DC power into three-phase AC power. The power module 22 has a housing 22a that houses the multiple combinations of switching elements and diodes. The power module 22 is capable of converting AC power supplied by the generator of the motor 14 into DC power. The power module 22 is housed in the housing 12. The housing 22a is mounted on the inner wall of the housing 12. The power module 22 is positioned above and in front of the smoothing capacitor 24.

[0055] (Positional relationship between the motor, gear unit, and inverter)

[0056] like Figure 2 As shown, the power module 22, smoothing capacitor 24, and noise filter 26 are arranged along the outer periphery of the shaft gear 32. In the left-right direction, i.e., the central axis X direction of the motor shaft 14b, the power module 22, smoothing capacitor 24, and noise filter 26 are arranged overlapping with the motor 14. Specifically, a portion of the end edge of the housing 22a of the power module 22, the housing 24a of the smoothing capacitor 24, and the housing 26a of the noise filter 26 does not overlap with the motor 14.

[0057] In the X-axis direction of the central axis of motor shaft 14b, 99% of the entire area of ​​power module 22, smoothing capacitor 24, and noise filter 26 overlaps with motor 14. In a modified example, in the X-axis direction of the central axis of motor shaft 14b, power module 22, smoothing capacitor 24, and noise filter 26 may overlap with motor 14 in the entire area (i.e., 100% of the area). At least one of power module 22, smoothing capacitor 24, and noise filter 26 may overlap with motor 14 in the entire area. Alternatively, in the X-axis direction of the central axis of motor shaft 14b, 50% to 100% of the entire area of ​​power module 22, smoothing capacitor 24, and noise filter 26 may overlap with motor 14. Preferably, in the X-axis direction of the central axis of motor shaft 14b, at least one of the following areas overlaps with motor 14: 60% to 100%, 70% to 100%, 80% to 100%, and preferably 90% to 100% of the entire area of ​​power module 22, smoothing capacitor 24, and noise filter 26.

[0058] In power module 22, the maximum length along the rotational direction R of shaft gear 32 is longer than the maximum length along the radial direction of shaft gear 32. Similarly, in smoothing capacitor 24, the maximum length along the rotational direction of shaft gear 32 is longer than the length along the radial direction of shaft gear 32. Similarly, in noise filter 26, the maximum length along the rotational direction of shaft gear 32 is longer than the maximum length along the radial direction of shaft gear 32. In other words, the long side of power module 22, smoothing capacitor 24, and noise filter 26 are respectively arranged along the rotational direction of shaft gear 32, while the short side is arranged along the radial direction of shaft gear 32.

[0059] In the rotational direction of the shaft gear 32, the angle AN from the end 22b of the power module 22 opposite to the smoothing capacitor 24 to the end 26b of the noise filter 26 opposite to the smoothing capacitor 24 is 240 degrees or more. Furthermore, the angle AN is preferably 180 degrees or more.

[0060] Preferably, the shortest distances from the central axis X of the power module 22, the smoothing capacitor 24, and the noise filter 26 are approximately equal. Furthermore, the smoothing capacitor 24 and the noise filter 26 are tilted relative to the power module 22 in the rotational direction R. That is, the power module 22, the smoothing capacitor 24, and the noise filter 26 are configured to intersect each other when extended along their respective long sides.

[0061] (Structure of the busbar unit)

[0062] Reference Figures 6 to 8 This indicates busbar units 60 and 70. Figure 6 From Figure 2 The side view of the drive unit 10 shown omits structural elements other than the bus units 60 and 70 of the inverter 20. The bus unit 60 extends from the noise filter 26 to the smoothing capacitor 24. The bus unit 60 is positioned horizontally between the motor 14 and the noise filter 26, and between the motor 14 and the smoothing capacitor 24. The bus unit 60 includes two buses 62 and 64 and a cover 66. The buses 62 and 64 are made of conductive material. The two buses 62 and 64 energize the noise filter 26 and the smoothing capacitor 24. Busbar 62 has a main body portion 62a that bends along the rotation direction R of shaft gear 32, i.e., along the outer periphery of motor 14, an end portion 62b that bends from the main body portion 62a and extends to noise filter 26, and an end portion 62c that bends from the main body portion 62a and extends to smoothing capacitor 24. Busbar 64 has a main body portion 64a that bends along the rotation direction R of shaft gear 32, i.e., along the outer periphery of motor 14, an end portion 64b that bends from the main body portion 64a and extends to noise filter 26, and an end portion 64c that bends from the main body portion 64a and extends to smoothing capacitor 24.

[0063] The end portions 62b, 64b are electrically connected to the smoothing capacitor 24. The end portions 62c, 64c are electrically connected to the noise filter 26. The main body portions 62a, 64a of the bus bars 62, 64 are covered by a cover 66. The cover 66 is attached to the inner wall of the housing 12. The cover 66 is made of an insulating material such as resin. Figure 8 is a perspective view of the cover 66 with the cover portion 66c (see Figure 6 ) removed. The cover 66 has a covering portion 66a, a wall portion 66b, and a cover portion 66c.

[0064] The covering portion 66a holds the bus bars 62, 64 by covering the main body portions 62a, 64a. The covering portion 66a insulates the main body portions 62a, 64a from the outside of the bus bars 62, 64. The covering portion 66a is curved in the same direction as the main body portions 62a, 64a in the rotation direction R. The wall portion 66b is disposed on the surface of the covering portion 66a on the inverter 20 side. The wall portion 66b protrudes perpendicularly from the surface of the covering portion 66a in the direction in which the end portions 62b, 64b, 62c, 64c extend. The wall portion 66b encircles the outer periphery of the surface of the covering portion 66a. The opening of the end portion on the side opposite the covering portion 66a of the wall portion 66b is closed by the cover portion 66c. The boundary between the wall portion 66b and the cover portion 66c is liquid-tightly sealed by a sealing member. The flow path 66d of the refrigerant is demarcated by the surface of the covering portion 66a, the wall portion 66b, and the cover portion 66c. The end portions 62b, 64b are isolated from the flow path 66d by a partition wall 66e protruding from the covering portion 66a. The end portions 62c, 64c are isolated from the flow path 66d by a partition wall 66f.

[0065] The flow path 66d communicates with the flow inlet 66g at the upper end via a through-hole formed in the wall portion 66b. The flow inlet 66g is provided to a cylindrical portion 66h disposed at the upper end of the covering portion 66a. The flow inlet 66g is located at the upper end portion of the bus bar unit 60. The flow path 66d communicates with the flow outlet 66j at the lower end via a through-hole formed in the wall portion 66b. The flow outlet 66j is provided to a cylindrical portion 66k disposed at the lower end of the covering portion 66a. The flow outlet 66j is located at the lower end portion of the bus bar unit 60. As shown in Figure 5 , the cylindrical portion 66k is connected to the communication pipe 12c provided to the housing 12. The communication pipe 12c is provided to the lower surface 12b. The flow outlet 66j communicates with the outside of the housing 12 via the communication pipe 12c.

[0066] The bus bar unit 70 extends from the power module 22 to the motor 14. As shown in Figure 7As shown, the bus bar unit 70 has three bus bars 72, 74, 76 and a cover 78. The bus bars 72, 74, 76 are made of the same conductive material as the bus bars 62, 64. The bus bars 72, 74, 76 respectively extend in the left-right direction from the front of the power module 22 to the front and upper side of the motor 14. The bus bars 72, 74, 76 correspond to each phase of three-phase alternating current. The bus bars 72, 74, 76 energize the power module 22 and the motor 14. The bus bar 72 has an end portion 72c in electrical contact with the power module 22, an end portion 72b in electrical contact with the motor 14, and a main body portion 72a between the end portions 72b, 72c. The bus bars 74, 76 have end portions 74b, 76b, end portions 74c, 76c, and main body portions 74a, 76a, like the bus bar 72.

[0067] The end portions 72b, 74b, 76b are electrically connected to the stator 14d of the motor 14. The end portions 72c, 74c, 76c are electrically connected to the power module 22. The main body portions 72a, 74a, 76a are covered by the cover 78. The cover 78 is attached to the inner wall of the housing 12. The cover 78 is made of the same insulating material as the cover 66. The cover 78 has a covering portion 78a and a flow path forming portion 78b.

[0068] The covering portion 78a holds the bus bars 72, 74, 76 by covering the main body portions 72a, 74a, 76a. The covering portion 78a insulates the main body portions 72a, 74a, 76a from the outside of the bus bars 72, 74, 76. Like the main body portions 72a, 74a, 76a arranged in front of the inverter 20, the covering portion 78a extends linearly in the left-right direction. The covering portion 78a has a quadrangular prism shape. The flow path forming portion 78b is attached to the end portion of the covering portion 78a on the motor 14 side.

[0069] The flow path forming portion 78b is formed integrally with the covering portion 78a. The flow path forming portion 78b has a flat shape extending from the end portion of the covering portion 78a to between the inverter 20 and the motor 14. The flow path forming portion 78b has a space inside as shown by a broken line. The inside space of the flow path forming portion 78b is a flow path 78c for refrigerant to flow. The flow path 78c is enlarged from the end portion of the covering portion 78a to between the inverter 20 and the motor 14. The bus bars 72, 74, 76 pass through the inside space of the flow path forming portion 78b. The flow path forming portion 78b has a partition wall 78d surrounding the bus bars 72, 74, 76 passing through the inside space. The bus bars 72, 74, 76 are insulated from the flow path 78c by the partition wall 78d.

[0070] The flow path 78c communicates at its upper end with the inlet 78e formed in the flow path forming section 78b. The inlet 78e is located in the cylindrical section 78f disposed at the upper end of the flow path forming section 78b. The cylindrical section 78f extends from the flow path forming section 78b in the left-right direction toward the inverter 20 side and bends upward at the middle position. The cylindrical section 78f protrudes upward from the upper surface 12a of the housing 12. Specifically, the cylindrical section 78f is disposed above the front end of the housing 12 and forward of its uppermost end. The flow path 78c communicates at its lower end with the outlet 78g formed in the flow path forming section 78b. The outlet 78g is located in the cylindrical section 78h disposed in the flow path forming section 78b. The cylindrical section 78h extends from the flow path forming section 78b in the left-right direction toward the inverter 20 side. The cylindrical section 78h is connected to the cylindrical section 66h via a connecting pipe (not shown). Thus, the flow path 78c is connected to the flow path 66d from the inlet 66g via the outlet 78g.

[0071] (Refrigerant flow)

[0072] like Figure 2 As shown, a cooling unit 80 is disposed above the drive unit 10. Figure 9 As shown, the electric vehicle 2 is equipped with one or more cooling circuits 110 for cooling the motor 14 and the inverter 20. The flow of refrigerant in the cooling circuit 110 is shown by thick arrows. Figure 9 A power supply sequence 120 is shown, indicating the order in which power is supplied between the battery pack 6 and the motor 14 via the inverter 20. A cooling unit 80 cools the power module 22 by means of refrigerant flowing through one or more cooling circuits 110. The cooling unit 80 is positioned above the power module 22. The refrigerant is a coolant (LLC) used to cool one or more devices mounted on the electric vehicle 2. Piping 116 for refrigerant flow, a radiator 112, and a water pump 114 are arranged in the cooling circuit 110. The cooling unit 80 cools the power module 22 by means of refrigerant flowing through piping disposed around the power module 22.

[0073] The flow paths 66d and 78c of bus units 60 and 70 are included in a cooling circuit for cooling inverter 20. Specifically, inlet 78e is connected to piping extending from cooling unit 80. Thus, refrigerant from cooling unit 80 flows from inlet 78e into flow path 78c. In flow path 78c, the refrigerant flows downward from inlet 78e to outlet 78g. The refrigerant flowing through flow path 78c cools buses 72, 74, and 76 by exchanging heat with the main body portions 72a, 74a, and 76a of buses 72, 74, and 76.

[0074] The refrigerant flowing out from the flow outlet 78g flows into the flow path 66d from the flow inlet 66g. In the flow path 66d, the refrigerant flows from the flow inlet 66g downward to the flow outlet 66j. The refrigerant flowing through the flow path 66d exchanges heat with the bus bars 62, 64 by flowing along the body portions 62a, 64a of the bus bars 62, 64. Thus, the bus bars 62, 64 are cooled. The refrigerant flowing out from the flow outlet 66j flows into the pipe of the cooling unit 80 from the communication pipe 12c.

[0075] (EFFECTS)

[0076] With the bus bar unit 60, the refrigerant is allowed to flow along the body portions 62a, 64a of the bus bars 62, 64. Thus, the heat of the bus bars 62, 64 is efficiently released into the refrigerant. The same is true of the bus bar unit 70, and the heat of the bus bars 72, 74, 76 is efficiently released into the refrigerant.

[0077] With the bus bar unit 60, the flow path 66d of the refrigerant is allowed to be arranged integrally with the cover 66 that holds the bus bars 62, 64. Thus, it is not necessary to separately arrange the flow path of the refrigerant. The same is true of the bus bar unit 70.

[0078] In the bus bar unit 60, the flow inlet 66g is arranged at the upper end of the flow path 66d, and the flow outlet 66j is arranged at the lower end of the flow path 66d. According to this structure, the refrigerant in the flow path 66d is allowed to flow smoothly from the upper side to the lower side. The same is true of the bus bar unit 70.

[0079] The flow inlet 78e of the bus bar unit 70 protrudes upward from the upper surface 12a of the housing 12. Thus, the flow inlet 78e is allowed to be easily communicated with the pipe of the cooling unit 80 arranged above the drive device 10. The cylindrical portion 78f constituting the flow inlet 78e is arranged at a position above the front end of the housing 12 and forward of the uppermost end. According to this structure, the space above the drive device 10 is allowed to be utilized.

[0080] In the bus bar unit 60, the cover 66 is arranged in the gap formed between the inverter 20 and the motor 14. The cover 66 is curved in the direction of rotation of the shaft gear 32. In addition, the bus bars 62, 64 are also curved in conformity with the shape of the cover 66. The cover 66 has a shape following the shape of the motor 14. Thus, the bus bar unit 60 is allowed to be arranged around the shaft gear 32. In addition, as shown in FIG. 1, the bus bar unit 60 almost completely overlaps the motor 14 in the direction of the central axis X. Thus, the drive device 10 is allowed to be downsized. Thus, the space of the electric automobile 2 is allowed to be effectively utilized. Figure 5

[0081] ​In the housing 12 of the drive unit 10, the lower surface 12b slopes upward from the front to the rear. This structure allows for the formation of space below the lower surface 12b, thus ensuring sufficient space for the components of the electric vehicle 2. In the drive unit 10, the connector 28 between the battery pack 6 and the inverter 20 can be positioned below the lower surface 12b. The battery pack 6 is positioned below the floor of the electric vehicle 2. This structure allows the connector 28 to be positioned close to the battery pack 6, thereby shortening the power cable 7 and reducing the space required for its placement. Alternatively, at least a portion of the battery pack 6 can be located below the drive unit 10.

[0082] In the drive unit 10, by arranging the noise filter 26, the smoothing capacitor 24, and the power module 22 sequentially from bottom to top in the inverter 20, the noise filter 26 can be positioned close to the connector 28. This shortens the bus wiring and other cabling when supplying power from the connector 28 to the noise filter 26, the smoothing capacitor 24, and the power module 22.

[0083] In the drive unit 10, the power module 22, smoothing capacitor 24, and noise filter 26 overlap with the motor 14 in the X direction of the central axis of the motor shaft 14b. According to this structure, the inverter 20 can be arranged in the space around the motor shaft 14b, which is created by the size difference (diameter difference) between the motor 14 and the shaft gear 32. This allows for efficient utilization of the space created by the size difference between the motor 14 and the shaft gear 32. For example, compared to a structure where the inverter 20 is centrally located above the motor 14, this structure increases the integration rate of the inverter 20 and effectively utilizes space.

[0084] like Figure 3 As shown, in the radial direction of the shaft gear 32, the inverter 20, namely the power module 22, the smoothing capacitor 24, and the noise filter 26, are arranged overlapping with the shaft gear 32. In the left-right direction, the shaft gear 32 is arranged at the center of the power module 22, the smoothing capacitor 24, and the noise filter 26. The shaft gear 32 extends along its entire length in the direction of the central axis X, overlapping radially with at least one of the power module 22, the smoothing capacitor 24, and the noise filter 26. Thus, the power module 22, the smoothing capacitor 24, and the noise filter 26 can be arranged in the space around the shaft gear 32, which is formed due to the dimensional difference between the motor 14 and the shaft gear 32. In a modified example, in the radial direction of the shaft gear 32, at least a portion of any one of the inverter 20, namely the power module 22, the smoothing capacitor 24, and the noise filter 26, can be arranged overlapping with the shaft gear 32. For example, at least a portion of the shaft gear 32 in the direction of the central axis X can be arranged radially without overlapping with any one of the power module 22, the smoothing capacitor 24, and the noise filter 26.

[0085] In the inverter 20, by separately arranging the power module 22, the smoothing capacitor 24, and the noise filter 26, the space around the shaft gear 32 can be effectively utilized.

[0086] In the power module 22, the maximum length in the rotational direction R of the shaft gear 32 is longer than the maximum length in the radial direction of the shaft gear 32. Similarly, in the smoothing capacitor 24, the maximum length in the rotational direction of the shaft gear 32 is longer than the length in the radial direction of the shaft gear 32. Similarly, in the noise filter 26, the maximum length in the rotational direction of the shaft gear 32 is longer than the maximum length in the radial direction of the shaft gear 32. In other words, the power module 22, the smoothing capacitor 24, and the noise filter 26 are respectively arranged with the long side direction in the rotational direction of the shaft gear 32 and the short side direction in the radial direction of the shaft gear 32. Thereby, the space around the shaft gear 32 can be effectively utilized, and the inverter 20 can be suppressed from being enlarged in the radial direction of the shaft gear 32.

[0087] In the rotational direction of the shaft gear 32, the angle AN from the end portion 22b of the power module 22 on the side opposite to the smoothing capacitor 24 with respect to the center axis X to the end portion 26b of the noise filter 26 on the side opposite to the smoothing capacitor 24 is 240 degrees or more. Further, the angle AN is preferably 180 degrees or more. In this structure, the space around the shaft gear 32 can be effectively utilized.

[0088] By arranging the majority of the secondary shaft gear 34 and the secondary shaft gear 42 at a position lower than the plane P of the center axis X of the motor shaft 14b and the center axis Y of the ring gear 50, the space in which the inverter 20 is arranged at a position higher than the plane P can be ensured to be enlarged. The angle range of the space higher than the plane P with the center axis X as the center becomes larger than the angle range of the space lower than the plane P.

[0089] The power module 22 and the secondary shaft gear 34 are arranged sandwiching the shaft gear 32. In order to exert the deceleration function of the motor 14, the diameter of the secondary shaft gear 34 is larger than the diameter of the shaft gear 32. Further, among the respective structural elements of the inverter 20, the size of the power module 22 is the largest. By arranging the power module 22 and the secondary shaft gear 34, which are large in size, sandwiching the shaft gear 32, the power module 22 and the secondary shaft gear 34 can be arranged without interfering with each other. The shaft gear 32 has the smallest diameter among the plurality of gears included in the gear unit 30. Therefore, by arranging the power module 22, the smoothing capacitor 24, and the noise filter 26 around the shaft gear 32, the size of the outer shape of the drive device 10 can be suppressed to be small compared to a structure in which gears other than the shaft gear 32 included in the plurality of gears in the gear unit 30 are arranged around the gears.

[0090] The pinion gear 32 is an example of a "first gear". The counter gear 34 is an example of a "second gear".

[0091] The above describes specific examples of the technology disclosed in the present specification, but these are merely examples and do not limit the scope of protection. The technology recited in the claims includes various modified and changed technical solutions of the above-described specific examples. The following lists modifications of the above-described embodiments.

[0092] (Modification 1) The drive device 10 can be disposed at the rear end portion of the vehicle. In this case, the lower surface 12b of the drive device 10 can be inclined upward toward the center C of the front-rear direction of the electric vehicle 2, that is, toward the front of the electric vehicle 2. In this case, the connector 28 can be disposed at a position lower than the front end of the drive device 10 and forward of the lowermost end. In addition, in this case, the flow inlet 78e can be disposed at a position upward of the rear end and rearward of the uppermost end.

[0093] (Modification 2) In the present embodiment, the power module 22, the smoothing capacitor 24, and the noise filter 26 are disposed side by side in the rotation direction R. However, at least two of the power module 22, the smoothing capacitor 24, and the noise filter 26 can also be disposed side by side in the radial direction of the pinion gear 32. Alternatively, at least two of the power module 22, the smoothing capacitor 24, and the noise filter 26 can also be disposed side by side in the axial direction of the center axis X, that is, in the left-right direction. For example, the power module 22, the smoothing capacitor 24, and the noise filter 26 can be collectively disposed above the pinion gear 32.

[0094] (Modification 3) The number of gears disposed in the gear unit 30 is not limited. In the present embodiment, the rotational speed of the motor 14 is reduced in two stages. However, the rotation of the motor 14 can also be reduced in three stages. In this case, at least eight gears can be provided in the gear unit 30. Among the plurality of gears included in the gear unit 30, the pinion gear 32 has the smallest diameter.

[0095] (Modification 4) In either of the bus bar units 60, 70, the flow path of the refrigerant can not be disposed in the cover 66, 78. In this case, the flow path of the refrigerant can be disposed at a position different from the cover 66, 78.

[0096] (Modification 5) The bus bar unit 60 can not be bent in the rotation direction R. For example, the bus bar unit 60 can be formed in a straight line shape.

[0097] (Modification 6) At least one of the bus bar units 60, 70 can be used in an electrical device other than the electric vehicle 2. In particular, it can be used for a bus bar used in an environment of at least one of a large current and a high temperature.

[0098] The technical elements described in the specification or the drawings can exert technical utility alone or through various combinations, and are not limited to the combinations recited in the claims at the time of filing. Furthermore, the technologies exemplified in the specification or the drawings can achieve multiple objects at the same time, and achieving one of the objects itself has technical utility.

[0099] Reference Signs List

[0100] 2: electric vehicle, 4: vehicle body, 6: battery pack, 10: drive device, 12: housing, 12b: lower surface, 12c: communication pipe, 14: motor, 14b: motor shaft, 20: inverter, 22: power module, 24: smoothing capacitor, 26: noise filter, 28: connector, 30: gear unit, 32: axle gear, 34: countershaft gear, 42: countershaft gear, 44: shaft, 50: ring gear, 52: differential gear, 60: bus bar unit, 62, 64: bus bar, 66: cover, 70: bus bar unit, 72, 74, 76: bus bar, 80: cooling unit, 90: drive shaft, X: center axis

Claims

1. A drive device, wherein, Possessing: a motor, possessing a motor shaft; a first gear, rotating with a center axis of the motor shaft as a center; and an inverter, possessing a plurality of structural elements for controlling the motor, in the center axis direction, at least a part of the inverter overlaps with the motor, in a radial direction of the first gear, at least a part of the inverter overlaps with the first gear.

2. The drive device according to claim 1, wherein the plurality of structural elements possess: a power module, possessing a plurality of switching elements; a smoothing capacitor; and a noise filter, the power module, the smoothing capacitor, and the noise filter are arranged in this order from above toward below.

3. The drive device according to claim 2, wherein in each of the power module, the smoothing capacitor, and the noise filter, a length in a rotation direction of the first gear is longer than a length in the radial direction of the first gear, a range from an end on a side opposite to the smoothing capacitor of the power module to an end on a side opposite to the smoothing capacitor of the noise filter in the rotation direction of the first gear is 180° or more around the center axis.

4. The drive device according to claim 2 or 3, wherein a second gear meshing with the first gear is further possessed, the first gear is arranged between the second gear and the power module.

5. The drive device according to claim 4, wherein the second gear is arranged at a position lower than the first gear and the power module. Possessing:

6. The drive apparatus according to any one of claims 1 to 3, wherein a plurality of shafts, including the motor shaft and a drive shaft; and one or more gears arranged respectively to the plurality of shafts, the one or more gears arranged to the motor shaft include the first gear.

7. The drive device according to claim 6, wherein among outer diameters of the one or more gears, an outer diameter of the first gear is the smallest. ​

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