Driving device

Abstract

To provide technology which can effectively use a space.SOLUTION: A driving device includes: a motor having a motor shaft; a first gear which rotates around a central axis of the motor shaft; and an inverter including a plurality of components used for controlling the motor. In a central axis direction, at least a part of the inverter is overlapped with the motor, and in a radial direction of the first gear, at least a part of the inverter may be overlapped with the first gear.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] Patent Document 1 discloses a drive unit including a motor and an electric motor control device that controls the motor. The electric motor control device is disposed above the motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-40578 A Summary of the Invention [Problem to be solved by the invention]

[0004] There are many parts that must be mounted in a limited mounting space in a vehicle, and there is a demand for effective use of the mounting space.

[0005] The present specification provides a technique that allows for efficient use of space. [Means for solving the problem]

[0006] A first aspect disclosed in the present specification relates to a drive device. The drive device includes a motor having a motor shaft, a first gear rotating around a central axis of the motor shaft, and an inverter having a plurality of components used to control the motor, and at least a portion of the inverter may overlap with the motor in the central axis direction, and at least a portion of the inverter may overlap with the first gear in the radial direction of the first gear.

[0007] In this configuration, the inverter is disposed in the space around the motor shaft that is generated by the dimensional difference between the motor and the first gear, making it possible to effectively utilize the space around the motor shaft.

[0008] Details and further improvements of the technology disclosed in this specification are described in the following "Forms for Carrying Out the Invention". [Brief description of the drawings]

[0009] [Figure 1] 1 is a side view of an electric vehicle equipped with a drive device according to an embodiment of the present invention; [Diagram 2] FIG. 2 shows a side view of the drive unit with the casing removed. [Diagram 3] FIG. 2 shows a schematic internal configuration diagram of a drive device. [Figure 4] FIG. [Diagram 5] FIG. [Figure 6] FIG. 4 is a side view of the drive device for explaining the configuration of the busbar unit. [Figure 7] FIG. [Figure 8] FIG. [Figure 9] A block diagram of the cooling circuit is shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] In a second aspect disclosed in the present specification, in the first aspect described above, the plurality of components may include a power module having a plurality of switching elements, a smoothing capacitor, and a noise filter, and may be arranged from top to bottom in the following order: the power module, the smoothing capacitor, and the noise filter.

[0011] According to this configuration, by arranging the battery near the lower end of the inverter, it is possible to shorten the wiring when power from the battery is supplied to the noise filter, smoothing capacitor, and power module in that order.

[0012] In a third aspect disclosed in the present specification, in the second aspect described above, the length of each of the power module, the smoothing capacitor, and the noise filter along the rotational direction of the first gear may be longer than the length of the first gear along the radial direction, and the range from the end of the power module opposite the smoothing capacitor in the rotational direction of the first gear to the end of the noise filter opposite the smoothing capacitor may be 180° or more around the central axis.

[0013] In this configuration, the longitudinal direction of each of the power module, the smoothing capacitor, and the noise filter is arranged along the rotation direction of the first gear, thereby making it possible to effectively utilize the space around the first gear.

[0014] In a fourth aspect disclosed in the present specification, in the second or third aspect described above, a second gear that meshes with the first gear may be further provided, and the first gear may be disposed between the second gear and the power module.

[0015] The power module is a relatively large component among the multiple components of the inverter. By disposing the power module on the opposite side of the first gear from the second gear, the power module and the second gear can be disposed efficiently.

[0016] In a fifth aspect disclosed in the present specification, in the above-mentioned fourth aspect, the second gear may be disposed below the first gear and the power module.

[0017] In this configuration, the torque of the motor is transmitted downward from the first gear to the second gear. This configuration allows the motor to be located above the drive shaft. This allows the power module and the second gear to be efficiently located, without having to significantly change the position of the motor relative to the drive shaft.

[0018] In a sixth aspect disclosed in the present specification, in any one of the first to fifth aspects above, the invention further comprises a plurality of shafts including the motor shaft and a drive shaft, and one or more gears arranged on each of the plurality of shafts, and the one or more gears arranged on the motor shaft may include the first gear.

[0019] With this configuration, the torque of the motor can be transmitted to the drive shaft via a plurality of gears.

[0020] In a seventh aspect disclosed in the present specification, in the sixth aspect described above, an outer diameter of the first gear may be the smallest among the outer diameters of the one or more gears.

[0021] According to this configuration, by arranging a plurality of components of the inverter around the first gear, which is the smallest of the plurality of gears between the motor and the axle, it is possible to make effective use of space.

[0022] (Example) FIG. 1 is a schematic diagram showing a front part of an electric vehicle 2 equipped with a drive unit 10 according to an embodiment, as seen from the side. In addition to the drive unit 10, the electric vehicle 2 includes a body 4, a battery pack 6, a suspension member 8, and a pair of front wheels 100. Although not shown, the electric vehicle 2 is equipped with a pair of rear wheels, a control device, and other devices for operating the electric vehicle 2. For ease of understanding, FIG. 1 shows components other than the drive unit 10 and the suspension member 8 with dashed lines. Furthermore, in order to make the drawing easier to see, the outer diameter shapes of each part are shown in a simplified manner. The electric vehicle 2 includes vehicles that use an electric motor for at least part of the driving, such as hybrid vehicles and fuel cell vehicles, in addition to electric vehicles. In the following, "upper", "lower", "left", "right", "front", and "rear" are described based on the coordinate system in the drawing.

[0023] (Driver configuration) The drive unit 10 is located forward of a front seat (not shown) of the electric vehicle 2. The drive unit 10 is disposed in a compartment forward of the passenger space in which the occupants of the electric vehicle 2 are located. The drive unit 10 is disposed between a pair of front wheels 100 located at both ends in the left-right direction of the electric vehicle 2. The drive unit 10 is located rearward of a front trunk 9 located near the front end of the electric vehicle 2. The front trunk 9 is separated from the passenger space and is a space in which luggage can be carried. The drive unit 10 is disposed forward of a vehicle center C of the electric vehicle 2 in the front-rear direction.

[0024] The drive unit 10 is fixed to a suspension member 8. The suspension member 8 is configured as a part of a suspension unit (not shown) including springs, dampers, etc., which are arranged on each of the pair of front wheels 100. The suspension member 8 holds the springs, dampers, etc. In this way, the suspension unit is mounted on the electric vehicle 2.

[0025] The drive unit 10 is protected by a casing 12. Fig. 2 shows a right side view of the inside of the casing 12 with the right side wall of the casing 12 removed. In addition to the casing 12, the drive unit 10 includes a motor 14, a gear unit 30, an inverter 20, and a drive shaft 90.

[0026] The casing 12 accommodates the motor 14, the gear unit 30, the inverter 20, and the drive shaft 90. The casing 12 defines an accommodation space in which a plurality of components are combined.

[0027] In the drive device 10, the inverter 20 converts the DC power of the battery pack 6 into AC power suitable for driving the motor 14. The battery pack 6 is disposed below a floor panel (not shown) of the electric vehicle 2. The battery pack 6 supplies power to the drive device 10. As a result, the drive device 10 drives a pair of front wheels 100. The drive device 10 also functions as a generator. The battery pack 6 stores the power supplied from the drive device 10.

[0028] The inverter 20 supplies AC power to the motor 14. The motor 14 is driven by the AC power from the inverter 20. The torque of the motor 14 is transmitted to a drive shaft 90 via a gear unit 30. The drive shaft 90 transmits the torque of the motor 14 to each of a pair of front wheels 100, thereby rotating the pair of front wheels 100. This drives the electric vehicle 2. The inverter 20 converts the AC power generated by the motor 14 into DC power and supplies it to the battery pack 6.

[0029] The motor 14 is disposed at the rear of the upper portion of the drive device 10. FIG. 3 shows the internal structure of the drive device 10 from the perspective of the lower front to the upper rear. In FIG. 3, the configuration of the inverter 20 is partially omitted in order to explain the gear unit 30. The motor 14 includes a main body 14a including 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 not shown, the stator 14d includes a stator core having a plurality of teeth and coils arranged on the plurality of teeth. The rotor 14c is disposed on the inner circumference of the stator 14d. The outer circumferential surface of the rotor 14c faces the inner circumferential surface of the stator 14d. The rotor 14c includes a plurality of permanent magnets arranged on the outer circumferential surface of the rotor 14c such that the polarities alternate in the circumferential direction. When AC power is supplied from the inverter 20 to each coil of the stator 14d, the magnetic field generated in the stator 14d changes. This causes the rotor 14c to rotate. The motor shaft 14b is arranged coaxially with the center of rotation of the rotor 14c. The motor shaft 14b extends straight from the main body 14a to the right.

[0030] (Gear unit configuration) Torque generated by driving the motor 14 is transmitted to the gear unit 30 via the motor shaft 14b. The gear unit 30 includes a shaft gear 32, a counter gear 34, a counter gear 42, a ring gear 50, a differential gear 52, and a shaft 44. The shaft gear 32, the counter gear 34, the counter gear 42, and the ring gear 50 each have a cylindrical shape with a plurality of teeth arranged on the outer circumferential surface. Teeth arranged on the shaft gear 32, the counter gear 34, the counter gear 42, and the ring gear 50 are not shown. The shaft gear 32 is attached to the motor shaft 14b. The motor shaft 14b is rotatably supported with respect to the casing 12 by bearings 36 and 38 attached to the casing 12. In the drive device 10, the gear unit 30 is in direct contact with the motor 14, so that the gear unit 30 and the motor 14 can be easily mechanically connected to each other.

[0031] The counter gear 34 meshes with the shaft gear 32 and rotates with the rotation of the shaft gear 32. The counter gear 34 is disposed below and in front of the shaft gear 32. The counter gear 34 is attached to a shaft 44. The shaft 44 is disposed parallel to the motor shaft 14b. The shaft 44 is disposed below and in front of the motor shaft 14b. The shaft 44 is rotatably supported relative to the casing 12 by bearings 46 and 48 attached to the casing 12. The counter gear 42 is attached to the shaft 44. As a result, the counter gear 42 is connected coaxially to the counter gear 34. The counter gear 42 rotates with the rotation of the counter gear 34. The ring gear 50 meshes with the counter gear 42 and rotates with the rotation of the counter gear 42.

[0032] The ring gear 50 is disposed below and in front of the counter gear 42. The ring gear 50 rotates about a central axis Y (see FIG. 2). The ring gear 50 is attached to a differential gear 52. The differential gear 52 rotates with the rotation of the ring gear 50. The differential gear 52 is a gear mechanism that rotates each of the pair of front wheels 100 independently by the rotation of the ring gear 50. The differential gear 52 is disposed below and in front of the ring gear 50. The differential gear 52 drives a drive shaft 90. The drive shaft 90 is disposed 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 about the central axis Y, and the pair of front wheels 100 rotate about the drive shaft 90. This causes the electric automobile 2 to run.

[0033] As described above, the counter gear 34 is disposed in front of and below the shaft gear 32. The counter gear 42 is disposed coaxially with the counter gear 34, i.e., arranged side by side in the left-right direction. The ring gear 50 is disposed in front of and below the counter gear 42. The differential gear 52 is disposed below and forward of the ring gear 50. In other words, the differential gear 52, the ring gear 50, the counter gear 42, the counter gear 34, and the shaft gear 32 are arranged rearward and upward. For this reason, as shown in FIG. 1, in the casing 12 that houses the gear unit 30, the upper surface 12a and the lower surface 12b are inclined upward from the front to the rear, i.e., toward the center C of the vehicle.

[0034] The central axis X of the motor shaft 14b (i.e., the central axis X of the shaft gear 32) and the central axis Y of the ring gear 50 are arranged in parallel. As shown in FIG. 2, most of the counter gear 34 is located below a plane P connecting the central axis X of the motor shaft 14b and the central axis Y of the ring gear 50. The counter gear 42 is located entirely below the plane P. In a modified example, the counter gear 34 may be located entirely below the plane P. With this configuration, a space can be provided above the gear unit 30. This makes it possible to arrange devices such as the inverter 20 above the gear unit 30.

[0035] The outer diameter of the counter gear 34 (i.e., the diameter of a circle connecting the tips of the 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 ring gear 50 is larger than the outer diameter of the counter gear 42. As a result, the rotation speed of the shaft gear 32 is reduced in two stages. Of the multiple gears 32, 34, 42, 50 arranged in the gear unit 30, the shaft gear 32 has the smallest outer diameter. In a modified example, a gear that is the same as or smaller than the shaft gear 32 may be arranged in the gear unit 30.

[0036] (Inverter configuration) As shown in FIG. 1, the inverter 20 is connected to the battery pack 6 by a power cable 7. The inverter 20 is a device for converting DC power of the battery pack 6 into AC power suitable for driving the motor 14. The inverter 20 is a high-voltage component to which high-voltage power is applied. Here, "high voltage" refers to an operating voltage of more than 60V DC and not more than 1500V, or more than 30V AC (effective value) and not more than 1000V (effective value). The inverter 20 is a device for converting AC power from the motor 14 into DC power suitable for the battery pack 6. In a modified example, the inverter 20 may convert DC power into AC power, but may not convert AC power into DC power.

[0037] 2, the inverter 20 includes a power module 22, a smoothing capacitor 24, a noise filter 26, a connector 28, and busbar units 60 and 70 (see FIG. 6). Power supplied from the battery pack 6 to the inverter 20 is input from the connector 28, passes through the noise filter 26, the busbar unit 60, the smoothing capacitor 24, the noise filter 26, and the busbar unit 70 in this order, and is supplied from the busbar unit 70 to the motor 14.

[0038] The connector 28 has a terminal (not shown) connected to a terminal of the power cable 7, and a cover 28a surrounding the terminal. The connector 28 penetrates the casing 12 and extends from the outside to the inside of the casing 12. The terminal extends in the left-right direction and is connected to the power cable 7. As shown in FIG. 2, the cover 28a protrudes downward and rearward from the lower surface 12b of the casing 12. The cover 28a is disposed in a space located below the lower surface 12b. The cover 28a is disposed below the rear end of the casing 12 and rearward of the lowest end.

[0039] The terminals of the connector 28 extend to the noise filter 26. The noise filter 26 is an electromagnetic compatibility (EMC (short for Electro Magnetic Compatibility)) noise filter. The noise filter 26 has circuit components (not shown) such as a capacitor and a choke coil, and a casing 26a that houses the circuit components. The noise filter 26 is housed in the casing 12. The casing 26a is attached to the inner wall of the casing 12. The noise filter 26 is disposed in front of and above the connector 28.

[0040] The noise filter 26 is connected to the smoothing capacitor 24 via the bus bar unit 60. The smoothing capacitor 24 has a capacitor (not shown) that absorbs voltage fluctuations, and a casing 24a that houses the capacitor. The smoothing capacitor 24 is housed in the casing 12. The casing 24a is attached to the inner wall of the casing 12. The smoothing capacitor 24 is disposed above the noise filter 26.

[0041] The smoothing capacitor 24 is connected to the power module 22 via wiring. The power module 22 converts the DC power of the battery pack 6 into AC power. The power module 22 supplies the converted AC power to the motor 14. The power module 22 has a plurality of combinations of switching elements (not shown) and diodes (not shown) arranged therein to convert the DC power into three-phase AC power. The power module 22 has a casing 22a that houses a plurality of combinations of switching elements and diodes. The power module 22 can convert the AC power supplied by the power generation of the motor 14 into DC power. The power module 22 is housed in the casing 12. The casing 22a is attached to the inner wall of the casing 12. The power module 22 is arranged above and in front of the smoothing capacitor 24.

[0042] (Positional relationship between the motor, gear unit, and inverter) 2, the power module 22, the smoothing capacitor 24, and the noise filter 26 are arranged side by side along the outer periphery of the shaft gear 32. In the left-right direction, i.e., in the direction of the central axis X of the motor shaft 14b, the power module 22, the smoothing capacitor 24, and the noise filter 26 are arranged to overlap the motor 14. In detail, part of the edge of the casing 22a of the power module 22, the casing 24a of the smoothing capacitor 24, and the casing 26a of the noise filter 26 do not overlap the motor 14.

[0043] In the direction of the central axis X of the motor shaft 14b, 99% of the entire area of ​​the power module 22, the smoothing capacitor 24, and the noise filter 26 overlaps with the motor 14. In a modified example, in the direction of the central axis X of the motor shaft 14b, the power module 22, the smoothing capacitor 24, and the noise filter 26 may overlap with the motor 14 over the entire area (i.e., 100% area). At least one of the power module 22, the smoothing capacitor 24, and the noise filter 26 may overlap with the motor 14 over the entire area. Alternatively, in the direction of the central axis X of the motor shaft 14b, 50% to 100% of the entire area of ​​the power module 22, the smoothing capacitor 24, and the noise filter 26 may overlap with the motor 14. Preferably, in the direction of the central axis X of the motor shaft 14b, at least one of the following ranges of areas of the power module 22, the smoothing capacitor 24, and the noise filter 26 overlaps with the motor 14: 60% to 100%, 70% to 100%, 80% to 100%, and preferably 90% to 100%.

[0044] In the power module 22, the maximum length along the rotation direction R of the shaft gear 32 is longer than the maximum length along the radial direction of the shaft gear 32. Similarly, in the smoothing capacitor 24, the maximum length along the rotation direction of the shaft gear 32 is longer than the length along the radial direction of the shaft gear 32. Similarly, in the noise filter 26, the maximum length along the rotation direction of the shaft gear 32 is longer than the maximum length along 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 each arranged such that the longitudinal direction is aligned with the rotation direction of the shaft gear 32 and the lateral direction is aligned with the radial direction of the shaft gear 32.

[0045] In the rotation direction of the shaft gear 32, an angle AN from an end 22b of the power module 22 opposite the smoothing capacitor 24 to an end 26b of the noise filter 26 opposite the smoothing capacitor 24 is equal to or greater than 240 degrees. The angle AN is preferably equal to or greater than 180 degrees.

[0046] Preferably, the power module 22, the smoothing capacitor 24, and the noise filter 26 have approximately the same shortest distance from the central axis X. Moreover, the smoothing capacitor 24 and the noise filter 26 are each inclined in the rotation direction R with respect to the power module 22. That is, the power module 22, the smoothing capacitor 24, and the noise filter 26 are disposed so that they intersect with each other when extended in the longitudinal direction.

[0047] (Busbar unit configuration) The busbar units 60, 70 will be described with reference to Figs. 6 to 8. Fig. 6 is a side view of the drive device 10 shown in Fig. 2 with components of the inverter 20 omitted except for the busbar units 60, 70. The busbar unit 60 extends from the noise filter 26 to the smoothing capacitor 24. The busbar unit 60 is disposed between the motor 14 and the noise filter 26 and between the motor 14 and the smoothing capacitor 24 in the left-right direction. The busbar unit 60 includes two busbars 62, 64 and a cover 66. The busbars 62, 64 are made of a conductive material. The two busbars 62, 64 conduct electricity between the noise filter 26 and the smoothing capacitor 24. Each of the bus bars 62, 64 has a main body portion 62a, 64a that curves along the rotational direction R of the shaft gear 32, i.e., along the outer peripheral shape of the motor 14, an end portion 62b, 64b that is bent from the main body portion 62a, 64a and extends to the noise filter 26, and an end portion 62c, 64c that is bent from the main body portion 62a, 64a and extends to the smoothing capacitor 24.

[0048] The ends 62b, 64b are electrically connected to the smoothing capacitor 24. The ends 62c, 64c are electrically connected to the noise filter 26. The main body portions 62a, 64a of the bus bars 62, 64 are covered with a cover 66. The cover 66 is attached to the inner wall of the casing 12. The cover 66 is made of an insulating material such as resin. FIG. 8 is a perspective view of the cover 66 with the lid portion 66c (see FIG. 6) removed. The cover 66 includes a covering portion 66a, a wall portion 66b, and a lid portion 66c.

[0049] The covering portion 66a holds the busbars 62 and 64 by covering the main body portions 62a and 64a. The covering portion 66a insulates the main body portions 62a and 64a from the outside of the busbars 62 and 64. The covering portion 66a is curved along the rotation direction R, similar to the main body portions 62a and 64a. A wall portion 66b is disposed on the surface of the covering portion 66a on the inverter 20 side. The wall portion 66b protrudes perpendicularly to the surface of the covering portion 66a in the direction in which the ends 62b, 64b, 62c, and 64c extend from the surface of the covering portion 66a. The wall portion 66b goes around the outer periphery of the surface of the covering portion 66a. An opening at the end of the wall portion 66b opposite to the covering portion 66a is closed by the lid portion 66c. The boundary between the wall portion 66b and the lid portion 66c is liquid-tightly sealed by a seal member. A flow path 66d for the coolant is defined by the surface of the covering portion 66a, the wall portion 66b, and the lid portion 66c. The ends 62b and 64b are separated from the flow path 66d by a partition wall 66e protruding from the covering portion 66a. The ends 62c and 64c are separated from the flow path 66d by a partition wall 66f protruding from.

[0050] The flow passage 66d communicates at its upper end with an inlet 66g through a through hole formed in the wall portion 66b. The inlet 66g is provided in a cylindrical portion 66h disposed at the upper end of the covering portion 66a. The inlet 66g is located at the upper end of the busbar unit 60. The flow passage 66d communicates at its lower end with an outlet 66j through a through hole formed in the wall portion 66b. The outlet 66j is provided in a cylindrical portion 66k disposed at the lower end of the covering portion 66a. The outlet 66j is located at the lower end of the busbar unit 60. As shown in FIG. 5, the cylindrical portion 66k is connected to a communication pipe 12c disposed in the casing 12. The communication pipe 12c is disposed on the lower surface 12b. The outlet 66j communicates with the outside of the casing 12 through the communication pipe 12c.

[0051] The busbar unit 70 extends from the power module 22 to the motor 14. As shown in FIG. 7, the busbar unit 70 includes three busbars 72, 74, 76 and a cover 78. The busbars 72, 74, 76 are made of the same conductive material as the busbars 62, 64. Each of the busbars 72, 74, 76 extends in the left-right direction from the front of the power module 22 to the front and above the motor 14. The busbars 72, 74, 76 correspond to each phase of the three-phase AC. The busbars 72, 74, 76 conduct electricity between the power module 22 and the motor 14. The busbar 72 includes an end 72c electrically contacting the power module 22, an end 72b electrically contacting the motor 14, and a body portion 72a between the ends 72b and 72c. Bus bars 74, 76, like bus bar 72, include ends 74b, 76b, ends 74c, 76c, and body portions 74a, 76a.

[0052] The ends 72b, 74b, 76b are electrically connected to the stator 14d of the motor 14. The ends 72c, 74c, 76c are electrically connected to the power module 22. The main body portions 72a, 74a, 76a are covered by a cover 78. The cover 78 is attached to the inner wall of the casing 12. The cover 78 is made of the same insulating material as the cover 66. The cover 78 includes a covering portion 78a and a flow path forming portion 78b.

[0053] 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. The covering portion 78a extends linearly in the left-right direction, similar to the main body portions 72a, 74a, 76a disposed in front of the inverter 20. The covering portion 78a has a quadrangular prism shape. A flow path forming portion 78b is attached to the end of the covering portion 78a on the motor 14 side.

[0054] 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 of the covering portion 78a to between the inverter 20 and the motor 14. The flow path forming portion 78b has a space inside, which is indicated by a dashed line. The internal space of the flow path forming portion 78b is a flow path 78c through which the refrigerant flows. The flow path 78c extends from the end of the covering portion 78a to between the inverter 20 and the motor 14. The bus bars 72, 74, and 76 penetrate the internal space of the flow path forming portion 78b. The flow path forming portion 78b includes a partition wall 78d that surrounds the bus bars 72, 74, and 76 that penetrate the internal space. The bus bars 72, 74, and 76 are insulated from the flow path 78c by the partition wall 78d.

[0055] The flow path 78c communicates at its upper end with an inlet 78e formed in the flow path forming portion 78b. The inlet 78e is provided in a cylindrical portion 78f disposed at the upper end of the flow path forming portion 78b. The cylindrical portion 78f extends from the flow path forming portion 78b along the left-right direction toward the inverter 20 side and is bent upward at the middle position. The cylindrical portion 78f protrudes upward from the upper surface 12a of the casing 12. In detail, the cylindrical portion 78f is disposed above the front end of the casing 12 and forward of the uppermost end. The flow path 78c communicates below the inlet 78e with an outlet 78g formed in the flow path forming portion 78b. The outlet 78g is provided in a cylindrical portion 78h disposed in the flow path forming portion 78b. The cylindrical portion 78h extends from the flow path forming portion 78b along the left-right direction toward the inverter 20 side. The cylindrical portion 78h is connected to the cylindrical portion 66h via a connecting pipe (not shown), so that the flow path 78c communicates with the flow inlet 66g and the flow path 66d via the flow outlet 78g.

[0056] (Refrigerant flow) As shown in FIG. 2, a cooling unit 80 is disposed above the drive unit 10. As shown in FIG. 9, the electric vehicle 2 is equipped with one or more cooling circuits 110 for cooling the motor 14 and the inverter 20. In the cooling circuits 110, the flow of the refrigerant is indicated by thick arrows. FIG. 9 shows a power supply sequence 120 indicating the sequence of power supply between the battery pack 6 and the motor 14 via the inverter 20. The cooling unit 80 cools the power module 22 by the refrigerant flowing through the one or more cooling circuits 110. The cooling unit 80 is disposed above the power module 22. The refrigerant is a coolant liquid (i.e., LLC) that cools one or more devices mounted on the electric vehicle 2. In the cooling circuit 110, a pipe 116 through which the refrigerant flows, a radiator 112, and a water pump 114 are disposed. The cooling unit 80 cools the power module 22 by the refrigerant flowing through a pipe disposed around the power module 22.

[0057] The flow paths 66d, 78c of the busbar units 60, 70 are included in a cooling circuit for cooling the inverter 20. In detail, the inlet 78e is connected to a pipe extending from the cooling unit 80. As a result, the refrigerant of the cooling unit 80 flows from the inlet 78e into the flow path 78c. In the flow path 78c, the refrigerant flows downward from the inlet 78e and reaches the outlet 78g. The refrigerant flowing through the flow path 78c exchanges heat with the main body portions 72a, 74a, 76a of the busbars 72, 74, 76, thereby cooling the busbars 72, 74, 76.

[0058] The refrigerant flowing out from outlet 78g flows into flow path 66d from inlet 66g. In flow path 66d, the refrigerant flows downward from inlet 66g and reaches outlet 66j. The refrigerant flowing through flow path 66d flows along main body portions 62a, 64a of bus bars 62, 64, thereby exchanging heat with bus bars 62, 64. This cools bus bars 62, 64. The refrigerant flowing out from outlet 66j flows into the piping of cooling unit 80 from communicating pipe 12c.

[0059] (effect) The busbar unit 60 allows the coolant to flow along the main body portions 62a, 64a of the busbars 62, 64. This allows the heat of the busbars 62, 64 to be efficiently released to the coolant. Similarly, the busbar unit 70 allows the heat of the busbars 72, 74, 76 to be efficiently released to the coolant.

[0060] According to the busbar unit 60, the coolant flow passage 66d can be disposed integrally with the cover 66 that holds the busbars 62, 64. This eliminates the need to provide separate coolant flow passages. The same applies to the busbar unit 70.

[0061] In the busbar unit 60, the inlet 66g is disposed at the upper end of the flow passage 66d, and the outlet 66j is disposed at the lower end of the flow passage 66d. This configuration allows the refrigerant in the flow passage 66d to flow smoothly from above to below. The same is true for the busbar unit 70.

[0062] The inlet 78e of the busbar unit 70 protrudes upward from the upper surface 12a of the casing 12. This makes it easy to connect the inlet 78e to the piping of the cooling unit 80 arranged above the drive unit 10. The cylindrical portion 78f constituting the inlet 78e is arranged above the front end of the casing 12 and forward of the uppermost end. With this configuration, the space above the drive unit 10 can be utilized.

[0063] In the busbar unit 60, the cover 66 is disposed in a gap formed between the inverter 20 and the motor 14. The cover 66 is curved along the rotation direction of the shaft gear 32. The busbars 62, 64 are curved following the shape of the cover 66. The cover 66 has a shape that follows the shape of the motor 14. This allows the busbar unit 60 to be disposed around the shaft gear 32. Also, as shown in FIG. 5, the busbar unit 60 overlaps with the motor 14 almost entirely in the direction of the central axis X. This allows the drive device 10 to be made smaller. This allows the space of the electric vehicle 2 to be used effectively.

[0064] In the casing 12 of the drive device 10, the lower surface 12b is inclined upward from the front to the rear. With this configuration, a space can be formed below the lower surface 12b. This makes it possible to secure a space for arranging the components of the electric vehicle 2. In the drive device 10, the connector 28 between the battery pack 6 and the inverter 20 can be arranged below the lower surface 12b. The battery pack 6 is arranged below the floor panel of the electric vehicle 2. With this configuration, the connector 28 can be arranged close to the battery pack 6. This makes it possible to shorten the power cable 7. The arrangement space for the power cable 7 can be reduced. Note that at least a part of the battery pack 6 may be located below the drive device 10.

[0065] In the drive device 10, by arranging the noise filter 26, the smoothing capacitor 24, and the power module 22 in this order from bottom to top in the inverter 20, the noise filter 26 can be arranged close to the connector 28. This makes it possible to shorten the wiring such as bus bars when supplying power from the connector 28 to the noise filter 26, the smoothing capacitor 24, and the power module 22 in this order.

[0066] In the drive device 10, the power module 22, the smoothing capacitor 24, and the noise filter 26 overlap with the motor 14 in the direction of the central axis X of the motor shaft 14b. With this configuration, the inverter 20 can be disposed in the space around the motor shaft 14b generated by the difference in size, i.e., the difference in diameter, between the motor 14 and the shaft gear 32. This allows the space generated by the difference in size between the motor 14 and the shaft gear 32 to be effectively utilized. With this configuration, the integration rate of the inverter 20 can be improved and the space can be effectively utilized, as compared with, for example, a configuration in which the inverter 20 is disposed all together in the space above the motor 14.

[0067] As shown in FIG. 3, the inverter 20, i.e., the power module 22, the smoothing capacitor 24, and the noise filter 26 are arranged so as to overlap with the shaft gear 32 in the radial direction of 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 overlaps at least one of the power module 22, the smoothing capacitor 24, and the noise filter 26 in the radial direction of the shaft gear 32 over the entire length in the direction of the central axis X. This allows the power module 22, the smoothing capacitor 24, and the noise filter 26 to be arranged in the space around the shaft gear 32 formed by the dimensional difference between the motor 14 and the shaft gear 32. In a modified example, the inverter 20, i.e., at least a part of any one of the power module 22, the smoothing capacitor 24, and the noise filter 26 may be arranged so as to overlap with the shaft gear 32 in the radial direction of the shaft gear 32. For example, at least a portion of the shaft gear 32 in the direction of the central axis X may not overlap any of the power module 22, the smoothing capacitor 24, and the noise filter 26 in the radial direction of the shaft gear 32.

[0068] In the inverter 20, the power module 22, the smoothing capacitor 24, and the noise filter 26 are arranged separately, so that the curved space around the shaft gear 32 can be effectively utilized.

[0069] In the power module 22, the maximum length along the rotation direction R of the shaft gear 32 is longer than the maximum length along the radial direction of the shaft gear 32. Similarly, in the smoothing capacitor 24, the maximum length along the rotation direction of the shaft gear 32 is longer than the length along the radial direction of the shaft gear 32. Similarly, in the noise filter 26, the maximum length along the rotation direction of the shaft gear 32 is longer than the maximum length along 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 each arranged such that the longitudinal direction is aligned with the rotation direction of the shaft gear 32 and the lateral direction is aligned with the radial direction of the shaft gear 32. This makes it possible to effectively utilize the space around the shaft gear 32 while suppressing the inverter 20 from expanding in the radial direction of the shaft gear 32.

[0070] In the rotation direction of the shaft gear 32, an angle AN from an end 22b of the power module 22 opposite the smoothing capacitor 24 to an end 26b of the noise filter 26 opposite the smoothing capacitor 24 with respect to the central axis X is 240 degrees or more. Note that the angle AN is preferably 180 degrees or more. With this configuration, the space around the shaft gear 32 can be effectively utilized.

[0071] By disposing most of the counter gear 34 and the counter gear 42 below the plane P that connects the central axis X of the motor shaft 14b and the central axis Y of the ring gear 50, a wide space can be secured above the plane P for disposing the inverter 20. The angular range of the space above the plane P, centered on the central axis X, can be made wider than the angular range of the space below the plane P.

[0072] The power module 22 and the counter gear 34 are arranged with the shaft gear 32 in between. The counter gear 34 has a larger diameter than the shaft gear 32 to achieve the deceleration function of the motor 14. The power module 22 is the largest among the components of the inverter 20. By arranging the power module 22 and the counter gear 34, which are large in size, with the shaft gear 32 in between, the power module 22 and the counter gear 34 can be arranged without interfering with each other. The shaft gear 32 has the smallest diameter among the multiple 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 external dimensions of the drive device 10 can be kept small compared to a configuration in which the power module 22, the smoothing capacitor 24, and the noise filter 26 are arranged around the gears other than the shaft gear 32 among the multiple gears included in the gear unit 30.

[0073] The shaft gear 32 is an example of a “first gear.” The counter gear 34 is an example of a “second gear.”

[0074] Although specific examples of the technology disclosed in this specification have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. Modifications of the above embodiments are listed below.

[0075] (Variation 1) The drive unit 10 may be disposed at the rear end of the vehicle. In this case, the lower surface 12b of the drive unit 10 may be inclined upward toward the center C in the front-rear direction of the electric vehicle 2, i.e., toward the front of the electric vehicle 2. In this case, the connector 28 may be disposed below the front end of the drive unit 10 and forward of the lowermost end. Also, in this case, the inlet 78e may be disposed above the rear end and rearward of the uppermost end.

[0076] (Modification 2) In this embodiment, the power module 22, the smoothing capacitor 24, and the noise filter 26 are arranged side by side along the rotation direction R. However, at least two of the power module 22, the smoothing capacitor 24, and the noise filter 26 may be arranged side by side in the radial direction of the shaft gear 32. Alternatively, at least two of the power module 22, the smoothing capacitor 24, and the noise filter 26 may be arranged side by side in the axial direction of the central axis X, i.e., in the left-right direction. For example, the power module 22, the smoothing capacitor 24, and the noise filter 26 may be arranged together above the shaft gear 32.

[0077] (Variation 3) There is no limit to the number of gears arranged in the gear unit 30. In this embodiment, the rotation of the motor 14 is decelerated in two stages. However, the rotation of the motor 14 may be decelerated in three stages. In this case, at least eight gears may be arranged in the gear unit 30. The shaft gear 32 may have the smallest diameter among the multiple gears included in the gear unit 30.

[0078] (Variation 4) In either one of the busbar units 60, 70, the flow path of the coolant does not have to be disposed in the covers 66, 78. In this case, the flow path of the coolant may be disposed in a position different from the covers 66, 78.

[0079] (Modification 5) The busbar unit 60 does not have to be curved along the rotation direction R. For example, the busbar unit 60 may be formed in a straight line.

[0080] (Variation 6) At least one of the busbar units 60, 70 may be used in an electric device other than the electric vehicle 2. In particular, it may be used as a busbar used in at least one of a large current and high temperature environment.

[0081] The technical elements described in this specification or drawings have technical utility either alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technologies illustrated in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of these objectives is itself technically useful. [Explanation of symbols]

[0082] 2: electric vehicle, 4: body, 6: battery pack, 10: drive unit, 12: casing, 12b: underside, 12c: connecting pipe, 14: motor, 14b: motor shaft, 20: inverter, 22: power module, 24: smoothing capacitor, 26: noise filter, 28: connector, 30: gear unit, 32: shaft gear, 34: counter gear, 42: counter gear, 44: shaft, 50: ring gear, 52: differential gear, 60: busbar unit 62, 64: busbar, 66: cover, 70: busbar unit, 72, 74, 76: busbar, 80: cooling unit, 90: drive shaft, X: central axis

Claims

1. a motor having a motor shaft; a first gear that rotates around a central axis of the motor shaft; an inverter including a plurality of components used to control the motor; When viewed in the axial direction of the central axis, at least a portion of the inverter overlaps with the motor, A drive device, wherein at least a portion of the inverter overlaps with the first gear when viewed in a radial direction of the first gear.

2. A drive device as described in claim 1, wherein the inverter is arranged below a cooling unit that cools the inverter.

3. The plurality of components include: a power module including a plurality of switching elements; A smoothing capacitor; a noise filter; 3. The drive device according to claim 1, wherein the power module, the smoothing capacitor, and the noise filter are arranged in this order from top to bottom.

4. a length of each of the power module, the smoothing capacitor, and the noise filter along the rotation direction of the first gear is longer than a length of each of the power module, the smoothing capacitor, and the noise filter along the radial direction of the first gear; 4. The drive device according to claim 3, wherein a range from an end of the power module opposite the smoothing capacitor in the rotational direction of the first gear to an end of the noise filter opposite the smoothing capacitor is 180 degrees or more around the central axis.

5. a second gear that meshes with the first gear; The drive device according to claim 3 , wherein the first gear is disposed between the second gear and the power module.

6. The drive device according to claim 5 , wherein the second gear is disposed below the first gear and the power module.

7. a plurality of shafts including the motor shaft and a drive shaft; one or more gears disposed on each of the plurality of shafts; The drive device according to claim 1 or 2, wherein the one or more gears disposed on the motor shaft include the first gear.

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

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