JP7777942B2 - Drive unit - Google Patents

Description

The present invention relates to a drive device.

In recent years, the popularity of electric and hybrid vehicles has led to the development of drive units for driving vehicles. Such drive units store fluids such as oil inside to lubricate gear surfaces and cool rotating electrical machines. Patent Document 1 discloses a structure in which oil stored at the bottom of a housing case is pumped up and flows through a cooling pipe that passes above an electric motor, and is then supplied to the electric motor from the cooling pipe's outlet.

Japanese Patent Application Laid-Open No. 2020-178520

In a drive unit with a fluid path for circulating a fluid, as the length of the fluid path increases, the resistance of the fluid path increases, leading to problems such as the need for a larger pump to pump the fluid and increased power consumption by the pump.

In consideration of the above-mentioned problems, one aspect of the present invention aims to provide a drive device that can shorten the fluid path through which the fluid flows and reduce the pipeline resistance of the fluid path.

One aspect of the drive device of the present invention comprises a motor having a motor shaft that rotates about a first axis, a power transmission mechanism connected to one axial side of the motor shaft, a housing having a motor accommodating section that houses the motor and a gear accommodating section that houses the power transmission mechanism, and a fluid path, at least a portion of which is disposed within the housing. The power transmission mechanism has a hollow shaft centered on a second axis that is parallel to the first axis. The fluid path includes a hollow shaft internal flow path section provided in the hollow shaft, a supply section provided above the motor, and a relay flow path section that connects the hollow shaft internal flow path section and the supply section.

One aspect of the present invention provides a drive unit that can shorten the fluid path through which the fluid flows, thereby reducing pipeline resistance.

FIG. 1 is a schematic diagram of a drive device according to a first embodiment. FIG. 2 is a schematic diagram of a drive device according to a second embodiment. FIG. 3 is a schematic diagram of a drive device according to a third embodiment.

Hereinafter, a driving device according to an embodiment of the present invention will be described with reference to the drawings.
In the following description, the vertical direction is defined based on the positional relationship when the drive device of the embodiment shown in each figure is mounted on a vehicle positioned on a horizontal road surface. The drawings also appropriately illustrate an XYZ coordinate system as a three-dimensional Cartesian coordinate system. In the XYZ coordinate system, the Z axis direction is the vertical direction. The +Z side is the upper side in the vertical direction, and the -Z side is the lower side in the vertical direction. In the following description, the upper side in the vertical direction is simply referred to as the "upper side," and the lower side in the vertical direction is simply referred to as the "lower side." The X axis direction is perpendicular to the Z axis direction and corresponds to the fore-and-aft direction of the vehicle on which the drive device is mounted. In the following embodiments, the +X side is the front side of the vehicle, and the -X side is the rear side of the vehicle. The Y axis direction is perpendicular to both the X axis direction and the Z axis direction and corresponds to the left-right direction of the vehicle, i.e., the vehicle width direction. In the following embodiments, the +Y side is the left side of the vehicle, and the -Y side is the right side of the vehicle. The fore-and-aft direction and the left-and-right direction are horizontal directions perpendicular to the vertical direction.

The first axis J1, shown appropriately in each figure, extends in the Y-axis direction, i.e., the left-right direction of the vehicle. In the following explanation, unless otherwise specified, the direction parallel to the first axis J1 will be referred to simply as the "axial direction," and the radial direction centered on the first axis J1 will be referred to simply as the "radial direction." Also, in the following explanation, the +Y side may be referred to simply as the one axial side, and the -Y side may be referred to simply as the other axial side.

First Embodiment
FIG. 1 is a schematic diagram of a drive device 1 according to a first embodiment.
The drive unit 1 is mounted on a vehicle powered by a motor, such as a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHV), or an electric vehicle (EV), and is used as the power source thereof.

The drive unit 1 includes a motor 2, a power transmission mechanism 3, a housing 6, a fluid O contained within the housing 6, a fluid path 90 through which the fluid O flows, a pump 8, and a plurality of bearings 83, 84, 85, 86, 87, 88, and 89.

(housing)
The housing 6 has a motor accommodating portion 81 that accommodates the motor 2 therein, and a gear accommodating portion 82 that accommodates the power transmission mechanism 3 therein. The housing 6 also has a partition wall 6b that separates the internal space of the motor accommodating portion 81 from the internal space of the gear accommodating portion 82. The gear accommodating portion 82 is located on one axial side (+Y side) of the motor accommodating portion 81.

The partition wall 6b is provided with a supply through hole 6s, a shaft passage hole 6p, and a partition wall opening 6q. The supply through hole 6s, the shaft passage hole 6p, and the partition wall opening 6q connect the internal spaces of the motor housing section 81 and the gear housing section 82.

The motor accommodating section 81 has a motor peripheral wall 6g and a motor cover wall 6c. The motor peripheral wall 6g is cylindrical and extends axially with the first axis J1 as its center. The motor peripheral wall 6g surrounds the motor 2 from the radially outer side of the first axis J1. The opening on one axial side (+Y side) of the motor peripheral wall 6g is covered by a partition wall 6b, and the opening on the other axial side (-Y side) is covered by the motor cover wall 6c. The motor cover wall 6c extends along a plane perpendicular to the first axis J1. The motor cover wall 6c covers the motor 2 from the other axial side (-Y side).

The gear accommodating section 82 has a gear peripheral wall portion 6f and a gear cover wall portion 6a. The gear peripheral wall portion 6f is cylindrical and extends along the axial direction. The gear peripheral wall portion 6f surrounds the gears 41, 42, 43, and 51 of the power transmission mechanism 3 from the radial outside of the first axis J1, second axis J2, and third axis J3 (described below). The opening on the other axial side (-Y side) of the gear peripheral wall portion 6f is covered by a partition wall 6b, and the opening on one axial side (+Y side) is covered by the gear cover wall portion 6a. The gear cover wall portion 6a extends along a plane perpendicular to the first axis J1. The gear cover wall portion 6a covers the power transmission mechanism 3 from one axial side (+Y side).

The housing 6 contains a fluid O. The fluid O circulates within a fluid path 90, which will be described later. In this embodiment, the fluid O is oil, and is used not only to cool the motor 2 but also to lubricate the power transmission mechanism 3. In order to function as both a lubricating oil and a cooling oil, it is preferable to use a relatively low-viscosity oil equivalent to automatic transmission lubricating oil (ATF: Automatic Transmission Fluid) as the fluid O.

A reservoir P is provided in the lower region of the gear accommodating section 82, where fluid O accumulates. The fluid O that accumulates in reservoir P is stirred up by the operation of the power transmission mechanism 3 and dispersed throughout the gear accommodating section 82. The fluid O dispersed within the gear accommodating section 82 spreads over the tooth surfaces of the power transmission mechanism 3 and is used to lubricate the power transmission mechanism 3. The fluid O in reservoir P is also supplied to the motor 2 via fluid path 90.

(Motor)
In this embodiment, the motor 2 is an inner rotor motor. The motor 2 is, for example, a three-phase AC motor. The motor 2 functions both as an electric motor and as a generator. The motor 2 includes a motor shaft 21, a rotor 20, and a stator 25.

The motor shaft 21 extends axially around the first axis J1. The motor shaft 21 rotates around the first axis J1. The motor shaft 21 is hollow. The motor shaft 21 has a hollow portion 22 that extends axially and is open at both ends.

The motor shaft 21 has a hollow first shaft portion 21A and a hollow second shaft portion 21B. The first shaft portion 21A and the second shaft portion 21B are arranged coaxially. The first shaft portion 21A and the second shaft portion 21B are connected to each other and rotate synchronously around the first axis J1.

The first shaft portion 21A is disposed inside the motor housing portion 81. The rotor 20 is fixed to the outer peripheral surface of the first shaft portion 21A. The second shaft portion 21B is disposed inside the gear housing portion 82. The power transmission mechanism 3 is connected to the second shaft portion 21B.

The motor shaft 21 extends across the motor accommodating section 81 and gear accommodating section 82 of the housing 6. The motor shaft 21 passes through the shaft passage hole 6p in the partition wall 6b. The connection between the first shaft portion 21A and the second shaft portion 21B is located inside the shaft passage hole 6p.

The rotor 20 is rotatable about the first axis J1. The rotor 20 has a rotor core and a rotor magnet fixed to the rotor core. The torque of the rotor 20 is transmitted to the power transmission mechanism 3.

The stator 25 surrounds the rotor 20 from the radial outside. The stator 25 has a stator core, a coil attached to the stator core, and an insulator (not shown) interposed between the stator core and the coil. The stator 25 is held in the housing 6. The stator core has multiple magnetic pole teeth (not shown) extending radially inward from the inner circumferential surface of the annular yoke. Coil wire is arranged between the magnetic pole teeth. The coil wire located in the gap between adjacent magnetic pole teeth constitutes a coil. The insulator is made of an insulating material.

(Power transmission mechanism)
The power transmission mechanism 3 transmits the power of the motor 2 to an output shaft 55 by a plurality of gears 41, 42, 43, and 51. The power transmission mechanism 3 is connected to the motor shaft 21 from one axial side (+Y side). The power transmission mechanism 3 has a reduction gear 4 and a differential gear 5.

The reduction gear 4 reduces the rotational speed of the motor 2 and increases the torque output from the motor 2 according to the reduction ratio. The reduction gear 4 transmits the torque output from the motor 2 to the differential gear 5.

The reduction gear 4 has a pinion gear 41, a hollow shaft 45, and a counter gear 42 and drive gear 43 fixed to the hollow shaft 45. In other words, the power transmission mechanism 3 has multiple gears 41, 42, 43 and the hollow shaft 45. Torque output from the motor 2 is transmitted to the ring gear 51 of the differential device 5 via the motor shaft 21 of the motor 2, the pinion gear 41, the counter gear 42, and the drive gear 43. The gear ratio of each gear, the number of gears, etc. can be changed depending on the required reduction ratio.

The pinion gear 41 is fixed to the outer peripheral surface of the motor shaft 21 of the motor 2. The pinion gear 41 rotates together with the motor shaft 21 around the first axis J1.

The hollow shaft 45 extends along a second axis J2 that is parallel to the first axis J1. That is, the hollow shaft 45 is centered on the second axis J2. In this embodiment, the second axis J2 is located above the first axis J1. Therefore, the hollow shaft 45 is located above the motor shaft 21. The hollow shaft 45 rotates around the second axis J2. The hollow shaft 45 is hollow. The hollow shaft 45 has a hollow portion 46 that extends axially and is open at both ends.

The counter gear 42 and drive gear 43 are arranged side by side in the axial direction. The counter gear 42 and drive gear 43 are provided on the outer circumferential surface of a hollow shaft 45. The counter gear 42 and drive gear 43 are connected via the hollow shaft 45. The counter gear 42 and drive gear 43 rotate about the second axis J2. At least two of the counter gear 42, drive gear 43, and hollow shaft 45 may be composed of a single member. The counter gear 42 meshes with the pinion gear 41. The drive gear 43 meshes with the ring gear 51 of the differential device 5.

The differential 5 is a device for transmitting the torque output from the motor 2 to the vehicle's wheels. When the vehicle turns, the differential 5 has the function of transmitting the same torque to a pair of output shafts 55 while absorbing the speed difference between the left and right wheels.

The differential device 5 has a ring gear (raising gear) 51. The ring gear 51 rotates about a third axis J3 that is parallel to the first axis J1. The torque output from the motor 2 is transmitted to the ring gear 51 via the reduction gear 4.

The pair of output shafts 55 extend axially. One end of each output shaft 55 is connected to a side gear, and the other end is connected to a wheel. The pair of output shafts 55 transmit the torque of the motor 2 to the road surface via the wheels.

In this embodiment, the ring gear 51 has a larger diameter than the other gears. Furthermore, at least a portion of the ring gear 51 is immersed in the reservoir P. Therefore, when the power transmission mechanism 3 drives the ring gear 51, it scoops up the fluid O in the reservoir P.

(bearing)
A plurality of bearings 83, 84, 85, 86, 87, 88, and 89 are held in the housing 6 and rotatably support either the motor shaft 21, the hollow shaft 45, or the output shaft 55, respectively.

Of the bearings 83, 84 that support the hollow shaft 45, one bearing 83 is held by the gear cover wall 6a, and the other bearing 84 is held by the partition wall 6b. Similarly, of the bearings 89 that support the output shaft 55, one is held by the gear cover wall 6a, and the other, not shown, is held by the partition wall 6b.

Of the bearings 87, 88 that support the first shaft portion 21A of the motor shaft 21, one bearing 87 is held by the partition wall 6b, and the other bearing 88 is held by the motor cover wall portion 6c. Of the bearings 85, 86 that support the second shaft portion 21B of the motor shaft 21, one bearing 85 is held by the gear cover wall portion 6a, and the other bearing 86 is held by the partition wall 6b. Bearings 86 and 87 are positioned inside the shaft passage hole 6p provided in the partition wall 6b.

The gear cover wall 6a has a first bearing retaining portion 61 that retains bearing 83 and a second bearing retaining portion 62 that retains bearing 85. Furthermore, the partition wall 6b has a third bearing retaining portion 63 that retains bearing 84. The motor cover wall 6c has a fourth bearing retaining portion 64 that retains bearing 88. The first bearing retaining portion 61 and the third bearing retaining portion 63 are cylindrical and centered on the second axis J2. The second bearing retaining portion 62 and the fourth bearing retaining portion 64 are cylindrical and centered on the first axis J1. A supply through hole 6s opens inside the third bearing retaining portion 63. That is, the supply through hole 6s of the partition wall 6b opens inside the third bearing retaining portion 63 toward the interior of the gear accommodating portion 82.

(Fluid Path)
The fluid O circulates through a fluid path 90 within the drive unit 1. The fluid path 90 supplies the fluid O from the reservoir P to the motor 2 and returns the fluid O to the reservoir P. At least a portion of the fluid path 90 is disposed within the housing 6.

In this specification, the term "fluid path " refers to the path of the fluid O circulating within the housing 6. Therefore, the term "fluid path " is a concept that includes not only a "flow path" that forms a steady flow of fluid in one direction, but also a path that temporarily retains fluid (for example, a reservoir), a path along which fluid drips, and a path along which fluid splashes.

A pump 8 is provided in the fluid path 90. The pump 8 pumps the fluid O in the fluid path 90. The pump 8 is fixed to the outer surface of the gear housing 82. The pump 8 pumps the fluid O in the fluid path 90. The pump 8 may be an electric pump that is driven electrically, or a mechanical pump that operates in conjunction with the driving of the power transmission mechanism 3.

Furthermore, a cooler for cooling the fluid O may be provided in the fluid path 90. This allows the motor 2 to be efficiently cooled via the fluid O. The cooler may be provided in the reservoir P and cool the fluid O that accumulates in the reservoir P.

The fluid path 90 in this embodiment includes a first flow path section 95, a hollow shaft internal flow path section 91, a relay flow path section 94, a supply pipe section (supply section) 92, a second flow path section 97, and a motor shaft internal flow path section 96.

The first flow path section 95 connects the reservoir section P with the hollow shaft internal flow path section 91 and the motor shaft internal flow path section 96. The first flow path section 95 guides the fluid O that accumulates in the reservoir section P to the hollow shaft internal flow path section 91 and the motor shaft internal flow path section 96.

The first flow path portion 95 is a hole provided in the gear cover wall portion 6a. In other words, the first flow path portion 95 is disposed inside the gear cover wall portion 6a. The first flow path portion 95 extends along the wall surface of the gear cover wall portion 6a.

The first flow path section 95 has a main flow path 95c and a first branch path 95a and a second branch path 95b branching from the main flow path 95c. The main flow path 95c is provided in the upstream region of the first flow path section 95. The upstream end of the main flow path 95c opens into the reservoir section P.

The first branch passage 95a connects the downstream end of the main passage 95c and the end of the hollow shaft internal flow path portion 91. The downstream end of the first branch passage 95a opens inside the first bearing holder 61. The first bearing holder 61 supports the hollow shaft 45 via the bearing 83. The hollow portion 46 of the hollow shaft 45 opens inside the first bearing holder 61. Fluid O flows from the first branch passage 95a into the inside of the first bearing holder 61 and further into the hollow shaft internal flow path portion 91 of the hollow shaft 45. In addition, the fluid O is supplied to the bearing 83 as it passes inside the first bearing holder 61, lubricating the bearing 83.

The second branch passage 95b connects the downstream end of the main passage 95c to the end of the motor shaft internal flow passage 96. The downstream end of the second branch passage 95b opens inside the second bearing holder 62. The second bearing holder 62 supports the motor shaft 21 via the bearing 85. The hollow portion 22 of the motor shaft 21 opens inside the second bearing holder 62. Fluid O flows from the second branch passage 95b into the inside of the second bearing holder 62 and further into the motor shaft internal flow passage 96 of the motor shaft 21. As the fluid O passes inside the second bearing holder 62, it is supplied to the bearing 85 and lubricates it.

In this embodiment, a pump 8 is disposed in the main flow path 95c of the first flow path section 95. The pump 8 is disposed in the flow path connecting the reservoir P and the hollow shaft internal flow path section 91, and sends fluid O from the reservoir P to the hollow shaft internal flow path section 91. The pump 8 is also disposed in the flow path connecting the reservoir P and the motor shaft internal flow path section 96, and sends fluid O from the reservoir P to the motor shaft internal flow path section 96. According to this embodiment, by disposing the pump 8 in the main flow path 95c located upstream of the first branch path 95a and the second branch path 95b, it is possible to supply fluid O to two internal shaft flow paths (the hollow shaft internal flow path section 91 and the motor shaft internal flow path section 96) using a single pump 8.

The hollow shaft internal flow path 91 is provided in the hollow shaft 45. The hollow shaft internal flow path 91 is a flow path that passes through the hollow portion 46 of the hollow shaft 45. The hollow shaft internal flow path 91 guides the fluid O from the end on one axial side (+Y side) of the gear accommodating portion 82 to the end on the other axial side (-Y side).

The relay flow path portion 94 connects the hollow shaft internal flow path portion 91 and the supply pipe portion 92. The relay flow path portion 94 is a flow path provided within the supply through-hole 6s of the partition wall 6b. Therefore, the relay flow path portion 94 extends linearly along the axial direction inside the partition wall 6b.

The upstream end of the relay flow path section 94 opens inside the third bearing holder 63. The third bearing holder 63 supports the hollow shaft 45 via the bearing 84. The hollow section 46 of the hollow shaft 45 opens inside the third bearing holder 63. Fluid O flows from the hollow shaft inner flow path section 91 into the inside of the third bearing holder 63 and then into the relay flow path section 94. As the fluid O passes inside the third bearing holder 63, it is supplied to the bearing 84, lubricating it.

The downstream end of the relay flow path section 94 opens into an upper region within the motor housing section 81. Furthermore, the end of one axial side (+Y side) of the supply pipe section 92 is inserted into the opening at the downstream end of the relay flow path section 94. Therefore, the fluid O flowing through the relay flow path section 94 flows into the supply pipe section 92 at the downstream end of the relay flow path section 94.

The supply pipe 92 extends axially inside the motor housing 81. The end of the supply pipe 92 on one axial side (+Y side) is supported by the partition wall 6b, and the end on the other axial side (-Y side) is supported by the motor cover wall 6c.

The supply pipe section 92 is disposed above the motor 2 inside the motor housing section 81. The supply pipe section 92 is provided with an injection hole 92h that opens toward the motor 2. Fluid O passing through the supply pipe section 92 is injected toward the motor 2 from the injection hole 92h provided in the supply pipe section 92. In this way, the supply pipe section 92 supplies fluid O to the motor 2 from outside the motor 2.

In this embodiment, the supply pipe section 92 is pipe-shaped. Therefore, by using the pump 8 to pressurize the fluid O into the supply pipe section 92, the pressure of the fluid O in the supply pipe section 92 can be increased and the fluid O can be sprayed toward the motor 2. This allows the fluid O to reach even the intricate parts of the motor 2, allowing for efficient cooling of the motor 2.

The fluid O supplied from the outside to the motor 2 via the supply pipe 92 absorbs heat from the stator 25 as it flows along the surface of the stator 25, cooling it. The fluid O then drips from the stator 25 to the lower region within the motor housing 81, and then returns to the reservoir P via the partition opening 6q.

The second flow path portion 97 connects the supply pipe portion 92 and the motor shaft internal flow path portion 96. The second flow path portion 97 is a hole provided in the motor cover wall portion 6c. In other words, the second flow path portion 97 is disposed inside the motor cover wall portion 6c. The second flow path portion 97 extends along the wall surface of the motor cover wall portion 6c.

The upstream end of the second flow path portion 97 opens into the upper region of the motor housing portion 81.
The other axial end (-Y side) of the supply pipe 92 is inserted into the opening at the upstream end of the second flow path 97. A portion of the fluid O flowing inside the supply pipe 92 flows into the second flow path 97.

The downstream end of the second flow path section 97 opens inside the fourth bearing holder 64. The fourth bearing holder 64 supports the motor shaft 21 via the bearing 88. The hollow section 22 of the motor shaft 21 opens inside the fourth bearing holder 64. Fluid O flows from the second flow path section 97 into the inside of the fourth bearing holder 64 and further into the motor shaft internal flow path section 96 of the motor shaft 21. As the fluid O passes inside the fourth bearing holder 64, it is supplied to the bearing 88 and lubricates the bearing 88.

The motor shaft internal flow path 96 is a path that passes through the hollow portion 22 of the motor shaft 21. That is, the motor shaft internal flow path 96 is provided in the motor shaft 21. In the motor shaft internal flow path 96, the fluid O flows along the axial direction. The motor shaft internal flow path 96 is connected to the first flow path 95 and the second flow path 97. The fluid O that flows into the hollow portion 22 of the motor shaft 21 from one axial side and the other axial side joins together in the motor shaft internal flow path 96.

The fluid O passing through the motor shaft internal flow path 96 is subjected to centrifugal force caused by the rotation of the rotor 20, and passes radially outward through the rotor 20, scattering radially outward and being supplied to the stator 25. As the fluid O passes through the rotor 20, it absorbs heat from the rotor 20, cooling it. Furthermore, the fluid O supplied to the stator 25 from the radially inner side absorbs heat from the stator 25 as it flows along the surface of the stator 25, cooling it from the inside.

According to this embodiment, a portion of the fluid O stored in the reservoir P cools the motor 2 from the outside via the supply pipe 92, and cools the motor 2 from the inside via the motor shaft inner flow path 96. In other words, according to this embodiment, the fluid O can be used to cool the inside and outside of the motor 2, thereby improving the cooling efficiency of the motor 2.

A portion of the fluid O passing through the motor shaft internal flow path 96 leaks out of the motor shaft 21 through the gap at the connection between the first shaft portion 21A and the second shaft portion 21B. The connection between the first shaft portion 21A and the second shaft portion 21B is located inside the shaft passage hole 6p in the partition wall 6b. The fluid O leaking out of the motor shaft 21 is supplied to the bearings 86, 87 located inside the shaft passage hole 6p in the partition wall 6b, lubricating the bearings 86, 87.

In this embodiment, a configuration may be adopted in which either the second branch passage 95b or the second flow path portion 97 is omitted. In other words, in this embodiment, a configuration may be adopted in which the fluid O is supplied to the motor shaft internal flow path portion 96 from only one axial side or the other axial side.

In this embodiment, the fluid path 90 has a hollow shaft internal flow path portion 91 that passes through the interior of the hollow shaft 45. The hollow shaft internal flow path portion 91 traverses the internal space of the gear accommodating portion 82 in a straight line. Therefore, in this embodiment, the portion of the fluid path 90 that reaches the supply pipe portion 92 from the reservoir portion P can be configured to be short and straight, thereby suppressing the pipeline resistance within the fluid path 90. As a result, the pump 8 can be made smaller and its power consumption can be reduced.

In this embodiment, by providing a portion of the fluid path 90 inside the hollow shaft 45, the processing costs of the housing 6 can be reduced compared to when the flow path from the pump discharge port to the supply pipe section is constructed solely from holes in the housing wall, allowing the drive unit 1 to be provided at low cost.

In this embodiment, a portion of the fluid path 90 is provided inside the hollow shaft 45, allowing fluid O to be supplied to the bearings 83, 84 that support both ends of the hollow shaft 45. This allows the bearings 83, 84 to be lubricated by fluid O without the need to provide a separate oil supply path.

In this embodiment, the second axis J2, which is the center of the hollow shaft 45, is located above the first axis J1, which is the center of the motor 2. This makes it easier to position the hollow shaft 45 closer to the supply pipe section 92 above the motor 2, and the relay flow path section 94 connecting the hollow shaft internal flow path section 91 and the supply pipe section 92 can be shortened. This reduces the pipeline resistance of the fluid path 90 from the hollow shaft internal flow path section 91 to the supply pipe section 92.

In addition, according to this embodiment, the center of the hollow shaft 45 is located above the first axis J1, so the hollow shaft 45 can be positioned far away from the oil surface in the reservoir P. This makes it difficult for the counter gear 42 and drive gear 43, which are provided on the outer surface of the hollow shaft 45, to become immersed in the fluid O in the reservoir P, thereby reducing the agitation resistance of the fluid O when the counter gear 42 and drive gear 43 rotate.

In this embodiment, the supply pipe section 92 is disposed on the second axis J2. According to this embodiment, the hollow shaft internal flow path section 91 and the supply pipe section 92 can be arranged in a straight line along the second axis J2. This allows the hollow shaft internal flow path section 91, relay flow path section 94, and supply pipe section 92 to be configured in a straight line, shortening the flow path length and reducing the pipeline resistance of the fluid path 90 from the hollow shaft internal flow path section 91 to the supply pipe section 92.

The hollow portion 46 of the hollow shaft 45 in this embodiment extends in the axial direction with a uniform cross-sectional shape (circular in this embodiment). Therefore, the hollow shaft inner flow path portion 91 in this embodiment has a uniform flow path cross-sectional area along its entire length. Similarly, the supply through hole 6s in this embodiment extends in the axial direction with a uniform cross-sectional shape (circular in this embodiment). Therefore, the relay flow path portion 94 in this embodiment has a uniform flow path cross-sectional area along its entire length.

In this embodiment, the flow path cross-sectional area S2 of the relay flow path section 94 is smaller than the flow path cross-sectional area S1 of the hollow shaft internal flow path section 91. According to this embodiment, the flow rate of the fluid O is increased when it flows from the hollow shaft internal flow path section 91 into the relay flow path section 94. This increases the pressure of the fluid O in the supply pipe section 92 located downstream of the relay flow path section 94, allowing the fluid O to be forcefully sprayed from the spray hole 92h of the supply pipe section 92, allowing the fluid O to reach deep within the motor 2.

Second Embodiment
FIG. 2 is a schematic diagram of a driving device 101 according to the second embodiment.
The driving device 101 of this embodiment differs from the first embodiment mainly in the configurations of the fluid path 190 and the catch tank 193 .
In the following description of each embodiment, the same components as those in the previously described embodiments are denoted by the same reference numerals, and the description thereof will be omitted.

In the present embodiment, a catch tank (reservoir) 193 is provided inside the gear accommodating portion 82. The catch tank 193 is open to the upper side and stores the fluid O. The catch tank 193 is provided above the second axis J2.
Here, "the catch tank 193 is provided above the second axis J2" means that the bottom of the catch tank 193 is located above the second axis J2.

The catch tank 193 is, for example, a trough-shaped member that protrudes from the inner surface of the gear accommodating portion 82. In this case, the catch tank 193 is part of the housing 6. Alternatively, the catch tank 193 may be a separate member from the housing 6.

The catch tank 193 functions as a reservoir for storing fluid O. Therefore, the reservoirs provided inside the housing 6 include the reservoir P provided in the lower region of the gear accommodating portion 82, as well as the catch tank 193 located above the reservoir P within the gear accommodating portion 82.

The fluid path 190 in this embodiment includes a scooping path 198, a first flow path section 195, a hollow shaft internal flow path section 91, a relay flow path section 94, a supply gutter section (supply section) 192, a communication flow path section 199, and a motor shaft internal flow path section 96.

The scooping path 198 is a path that scoops up the fluid O by the rotation of the gear (ring gear 51 in this embodiment) of the power transmission mechanism 3 and guides it to the catch tank 193. That is, in the fluid path 190 of this embodiment, the fluid O is supplied from the reservoir P to the catch tank 193 by being scooped up by the gear of the power transmission mechanism 3.

In this embodiment, the reservoir connected to the first flow path section 195 is the catch tank 193. The first flow path section 195 connects the catch tank 193 to the hollow shaft internal flow path section 91. The first flow path section 195 also connects the catch tank 193 to the communication flow path section 199. The first flow path section 195 guides the fluid O from the catch tank 193 to the hollow shaft internal flow path section 91 and the communication flow path section 199.

The communication flow path portion 199 connects the first flow path portion 195 and the motor shaft internal flow path portion 96. The communication flow path portion 199 is a hole provided in the gear cover wall portion 6a. In other words, the communication flow path portion 199 is disposed inside the gear cover wall portion 6a. The communication flow path portion 199 extends along the wall surface of the gear cover wall portion 6a.

The downstream end of the first flow path section 195 opens inside the first bearing holder 61. The hollow section 46 of the hollow shaft 45 opens inside the first bearing holder 61. Furthermore, the upstream end of the communication flow path section 199 opens inside the first bearing holder 61. The fluid O flows from the first flow path section 195 into the inside of the first bearing holder 61, and then branches off to flow into the hollow shaft internal flow path section 91 and the communication flow path section 199. As the fluid O passes inside the first bearing holder 61, it is supplied to the bearing 83, lubricating the bearing 83.

The downstream end of the communication flow path section 199 opens inside the second bearing holder 62. The hollow section 22 of the motor shaft 21 opens inside the second bearing holder 62. The fluid O flows from the communication flow path section 199 into the inside of the second bearing holder 62 and then into the motor shaft internal flow path section 96. As the fluid O passes inside the second bearing holder 62, it is supplied to the bearing 85, lubricating the bearing 85.

The supply gutter 192 is a gutter-shaped member disposed inside the motor accommodating section 81. The supply gutter 192 is connected to the downstream side of the relay flow path 94. The supply gutter 192 extends along the axial direction. The supply gutter 192 is located directly above the motor 2. A through-hole 192h is provided at the bottom of the supply gutter 192, through which the fluid O is supplied to the motor 2. The supply gutter 192 of this embodiment drips the fluid O stored inside from the through-hole 192h at the bottom toward the motor 2.
In this specification, "directly above" means arranged above and overlapping when viewed from the vertical direction.

In this embodiment, the supply gutter portion 192 is gutter-shaped, and the fluid O stored therein is supplied to the motor 2 by dripping from the through-holes 192h. Therefore, with the supply gutter portion 192 of this embodiment, even if the supply of fluid O from the reservoir portion P to the supply gutter portion 192 is interrupted, the fluid O stored in the supply gutter portion 192 can be supplied to the motor 2 in small amounts over a long period of time. Therefore, even if the supply of fluid O from the reservoir portion P to the supply gutter portion 192 is interrupted, the motor 2 can be cooled for a long period of time.

According to this embodiment, the catch tank 193 is located above the second axis J2. Therefore, the fluid O in the catch tank 193 is supplied to the hollow shaft internal flow path portion 91 and the motor shaft internal flow path portion 96 by utilizing gravity. Therefore, when a pump 8 is provided in the first flow path portion 195 as shown in this embodiment, the power consumption of the pump 8 can be reduced. Furthermore, by employing the fluid path 190 of this embodiment, the fluid O in the catch tank 193 can be supplied to the hollow shaft internal flow path portion 91 and the motor shaft internal flow path portion 96 by utilizing gravity. Therefore, in this embodiment, a configuration excluding the pump 8 from the first flow path portion 195 can be adopted, allowing for the provision of an inexpensive drive unit 101.

In this embodiment, a portion of the fluid O accumulated in the reservoir P is transferred to the catch tank 193 by the power transmission mechanism 3, where it is stored. This allows the level of the fluid O accumulated in the reservoir P to be lowered, and the stirring resistance of the gears immersed in the fluid O in the reservoir P can be reduced.

Third Embodiment
FIG. 3 is a schematic diagram of a driving device 201 according to a third embodiment.
The driving device 201 of this embodiment differs from the first embodiment mainly in the configuration of the fluid path 290 .

The fluid path 290 of this embodiment has a first flow path section 295, a hollow shaft internal flow path section 91, a relay flow path section 94, and a supply pipe section 92. Compared to the above-described embodiment, the fluid path 290 of this embodiment does not have a second flow path section 97 or a motor shaft internal flow path section 96.

In this embodiment, the first flow path portion 295 connects the reservoir portion P and the hollow shaft internal flow path portion 91. The first flow path portion 295 guides the fluid O that accumulates in the reservoir portion P to the hollow shaft internal flow path portion 91. The first flow path portion 295 is a hole provided in the gear cover wall portion 6a. In other words, the first flow path portion 295 is disposed inside the gear cover wall portion 6a. The first flow path portion 295 extends along the wall surface of the gear cover wall portion 6a.

In this embodiment, as in the above-described embodiment, the fluid path 290 linearly crosses the internal space of the gear accommodating section 82 in the hollow shaft internal flow path section 91. This allows the fluid path 290 to be shortened, thereby reducing pipeline resistance.

The above describes various embodiments of the present invention, but the configurations and combinations thereof in each embodiment are merely examples, and additions, omissions, substitutions, and other modifications to the configurations are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited to the embodiments.

1, 101, 201...Drive unit, 2...Motor, 3...Power transmission mechanism, 6...Housing, 6b...Bulkhead, 6c...Motor cover wall, 8...Pump, 21...Motor shaft, 41...Gear, 45...Hollow shaft, 81...Motor housing, 82...Gear housing, 90, 190, 290...Fluid path, 91...Hollow shaft internal flow path, 92...Supply pipe (supply section), 94...Relay flow path, 95, 195, 295...First flow path, 96...Motor shaft internal flow path, 97...Second flow path, 192...Supply trough (supply section), 193...Catch tank (storage section), 198...Path, J1...First axis, J2...Second axis, O...Fluid, P...Storage section, S1, S2...Flow path cross-sectional area

Claims (9)

a motor having a motor shaft that rotates about a first axis;
a power transmission mechanism connected to the motor shaft from one axial side;
a housing having a motor accommodating portion that accommodates the motor therein and a gear accommodating portion that accommodates the power transmission mechanism therein;
a fluid path at least partially disposed within the housing;
the power transmission mechanism has a hollow shaft centered on a second axis parallel to the first axis,
the motor shaft is hollow and extends into the gear accommodating portion at one axial side thereof,
the gear accommodating portion has a gear cover wall portion that covers the power transmission mechanism from one axial side,
The fluid path includes:
a hollow shaft inner flow path portion provided in the hollow shaft;
a supply unit provided above the motor;
a relay flow path portion connecting the hollow shaft inner flow path portion and the supply portion;
a motor shaft internal flow path portion provided in the motor shaft;
a first flow path portion that is provided inside the gear cover wall portion, extends along a wall surface of the gear cover wall portion, and is capable of supplying fluid to one axial end of the hollow shaft internal flow path portion and one axial end of the motor shaft internal flow path portion ,
the first flow path portion has a first branch path and a second branch path branching from the first branch path,
the first branch passage is connected at a downstream end thereof to one axial end of the hollow shaft internal flow passage portion,
the second branch passage is connected at a downstream end thereof to one axial end of the flow passage portion within the motor shaft,
a vertical position of the hollow shaft internal flow path portion and a vertical position of the motor shaft internal flow path portion are different from each other;
Drive unit. The second axis is located above the first axis.
The drive device according to claim 1 . The supply unit is disposed on the second axis.
3. The drive device according to claim 1 or 2. a pump provided in the fluid path;
The gear accommodating portion is provided with a storage portion,
The pump is provided in a flow path connecting the storage section and the hollow shaft inner flow path section.
The drive device according to any one of claims 1 to 3. The gear accommodating portion is provided with a storage portion provided above the second axis,
The fluid path is provided with the first flow path portion connecting the storage portion and the hollow shaft inner flow path portion.
The drive device according to any one of claims 1 to 3. the motor accommodating portion has a motor cover wall portion that covers the motor from the other axial side,
The fluid path includes :
a second flow path portion connecting the supply portion and the motor shaft internal flow path portion,
The second flow path portion is disposed inside the motor cover wall portion.
The drive device according to any one of claims 1 to 5. the housing has a partition wall that separates the motor accommodating portion from the gear accommodating portion,
The relay flow path portion is provided in the partition wall,
a flow path cross-sectional area of the relay flow path portion is smaller than a flow path cross-sectional area of the hollow shaft inner flow path portion;
The drive device according to any one of claims 1 to 6. The supply section is pipe-shaped.
The drive device according to any one of claims 1 to 7. The supply section is trough-shaped.
The drive device according to any one of claims 1 to 7.