Motor apparatus for vehicle

A motor apparatus for a vehicle includes a motor unit, an inverter unit, a case, and a pump. The case has a motor space, an inverter space, and a cooling passage, the motor space accommodating the motor unit, the inverter space accommodating the inverter unit, the cooling passage being configured to let cooling medium flow through the cooling passage to cool the motor unit and the inverter unit. The pump is configured to forward the cooling medium to the cooling passage, and is disposed in a surrounding space within the motor space, the surrounding space being at a periphery of a rotation angle sensor fixed to a shaft of the motor unit.

CROSS-REFERENCE TO THE RELATED APPLICATION

This application incorporates by references the subject matter of Application No. 2014-207365 filed in Japan on Oct. 8, 2014 on which a priority claim is based under 35 U.S.C. §119(a).

FIELD

The present invention relates to a motor apparatus (a prime mover in the form of an electric motor) for driving a vehicle.

BACKGROUND

An electric vehicle and a hybrid vehicle are equipped with a motor for running or driving the vehicle, and an inverter that generates AC power for driving the motor. The motor and the inverter are disposed near to each other, electrically connected to each other via, for example, a high voltage cable(s), and together compose a power plant.

Regarding this configuration, Patent Document 1 (Japanese Patent Laid-Open No. 2013-192374) discloses a device that accommodates both the motor and the inverter in a single case part to save the space and to reduce the number of components.

SUMMARY

Technical Problems

From the view point of saving the space, the device disclosed in Patent Document 1 preferably arranges the motor and the inverter in close proximity to each other within the single case part. However, since each of the motor and the inverter generates heat while operating, close arrangements of the motor and the inverter may hinder heat dissipation of the motor and the inverter. For this reason, it is desired to enhance a cooling performance for the motor and the inverter while saving space by disposing the motor and the inverter in proximity to each other.

With the foregoing problems in view, an object of the present invention is to provide a motor apparatus for a vehicle, the motor apparatus being capable of enhancing the cooling performance while saving space. Another object of the present invention is to achieve advantageous effects that cannot be achieved through the traditional art by employing the configurations described below in the embodiments of the present invention.

Solution to Problems

(1) A disclosed motor apparatus for a vehicle includes a motor unit configured to generate power for driving the vehicle; an inverter unit configured to generate AC power for driving the motor unit; a case having a motor space, an inverter space, and a cooling passage, the motor space accommodating the motor unit, the inverter space accommodating the inverter unit, the cooling passage being configured to let cooling medium flow through the cooling passage to cool the motor unit and the inverter unit; and a pump disposed in a surrounding space within the motor space, the surrounding space being at a periphery of a rotation angle sensor fixed to a shaft of the motor unit, the pump being configured to forward the cooling medium to the cooling passage.

Advantageous Effects

A disclosed motor apparatus for a vehicle can enhance cooling performance while saving space.

DESCRIPTION OF EMBODIMENTS

A motor apparatus for a vehicle will now be described with reference to the accompanying drawings. The embodiments described below are merely examples, and it is not intended to exclude various modifications and technical applications that are not described in the embodiments described below. The configurations of the embodiments can be carried out in various modified forms without departing from the subject matter of the embodiments, and can be selectively applied as occasion demands or can be combined suitably.

A motor apparatus for a vehicle (hereinafter, simply referred to as “motor apparatus”) according to this embodiment is mounted on an electric-powered vehicle, such as an electric vehicle and a hybrid vehicle, and converts electrical energy stored in batteries into mechanical energy. The motor apparatus (a prime mover in the form of an electric motor) is electrically connected to the batteries while mechanically connected to wheels. The motor apparatus generates rotational force from the electric power of the batteries, and transmits the rotational force to the wheels.

As illustrated inFIG. 3, the motor apparatus1according to this embodiment includes a motor unit20that generates power for driving the vehicle, and an inverter unit30that converts DC power supplied from the batteries (not illustrated) into AC power and that supplies the AC power to the motor unit20. Since the motor unit20and the inverter unit30each generate heat due to electrical resistance, mechanical friction, and the like while operating, the motor apparatus1is equipped with a cooling device4for cooling each of the motor unit20and the inverter unit30.

The cooling device4includes a radiator4a, and an upstream passage4band a downstream passage4ceach connecting the radiator4awith the motor apparatus1in series. The cooling device4cools the motor apparatus1by circulating a coolant (cooling medium) between the radiator4aand the motor apparatus1. The radiator4ais a heat dissipater that removes heat from the coolant. Each of the upstream passage4band the downstream passage4cis formed of a pipe(s) or a hose(s), for example, and functions as a path through which the coolant flows.

The coolant cooled by the radiator4aof the cooling device4is supplied to the motor apparatus1through the upstream passage4b, and after flowing out of the motor apparatus1, flows through the downstream passage4cinto the radiator4aagain to be cooled. The motor unit20and the inverter unit30are cooled by the coolant flowing through a cooling passage70formed in the inside of the motor apparatus1and in the vicinity of the motor unit20and the inverter unit30. In other words, the coolant cools the motor unit20and the inverter unit30while flowing through the cooling passage70.

Hereinafter, the configuration of the motor apparatus1is to be described.FIG. 1illustrates a section of the motor apparatus1without a pump50(to be described below), the section being imaginary cut across a vertical plane passing through a core axis O.FIG. 1omits hatching that represents sectional surfaces for a shaft21of the motor unit20, the inverter unit30, a resolver3, and bearings5,6(each to be detailed later).FIG. 2is a perspective view of the motor apparatus1, and illustrates a control circuit33of the inverter unit30by two-dot chain lines while omitting a top lid43(each to be detailed later). In the following description, the gravitational direction is referred to as low direction, and the opposite direction of the gravitational direction is referred to as up direction. The motor apparatus1is to be mounted on the vehicle, keeping the orientation (of the vertical direction) illustrated inFIGS. 1 and 2.

As depicted inFIGS. 1 and 2, the motor apparatus1includes a case40and the pump50in addition to the motor unit20and the inverter unit30. The case40has multiple rooms inside, and accommodates the motor unit20and the inverter unit30. The pump50is fixed to the case40. In this embodiment, the inverter unit30is accommodated in a room62(hereinafter, referred to as “inverter space62”) disposed at an upper portion of the inside of the case40, while the motor unit20is accommodated in a room61(hereinafter, referred to as “motor space61”) disposed below the inverter space62.

Firstly, the configuration of the inverter unit30is to be detailed. The inverter unit30is configured to operate using the power of the batteries as the power source, and to convert DC power supplied from the batteries into AC power (i.e. the inverter unit30is configured to generate AC power) for driving the motor unit20, and to supply the AC power to the motor unit20. The inverter unit30includes a power converter31, a capacitor32, and the control circuit33.

The power converter31includes multiple switching elements, such as thyristors and transistors called IGBT (Insulated Gate Bipolar Transistor), and is configured to convert DC power into AC power by turning on and off the switching elements. The capacitor32is disposed on an electrical circuit connecting the batteries and the power converter31, and is configured to smooth the DC power supplied from the batteries. The control circuit33takes the form of a control board, and is configured to control the on/off state of the switching elements included in the power converter31.

Among the elements of the inverter unit30, the power converter31and the capacitor32, especially, tend to have elevated temperatures since each of the power converter31and the capacitor32generates large amount of heat due to large current flowing from the batteries. To deal with this inconvenience, as shown inFIG. 1, the cooling passage70(a first part71and a second part72each to be detailed later) is disposed in proximity to the power converter31and the capacitor32to cool the power converter31and the capacitor32.

Next, the configuration of the motor unit20is to be detailed. The motor unit20is configured to generate rotational force to be transmitted to the wheels (not shown) by rotating a rotor with the AC power generated in the inverter unit30. The motor unit20configures a three-phase AC motor. As illustrated inFIG. 1, the motor unit20includes the rotor constituted by the shaft21and a rotor core24being fixed to the periphery of the shaft21and having a magnet(s)25embedded in the rotor core24. The motor unit20further includes a stator constituted by a number of stator cores23arranged along the circumference of the rotor core24at constant intervals, and coils22wound around the respective stator cores23. Each of the stator cores23is fixed to an inner wall of the case40, the inner wall surrounding the motor space61.

The shaft21of this embodiment is disposed so as to have the core axis O extending horizontally, and is rotatably supported by two bearings5,6each fixed to the case40. A first end21a(the left end inFIG. 1, and hereinafter also referred to as “output end21a”) of the shaft21protrudes outside the case40, and is connected to an axle via a gear box (not illustrated), for example. The other end or a second end21b(the right end inFIG. 1, and hereinafter also referred to as “sensor end21b”) of the shaft21is received in a bulge portion42b(to be described later) disposed in the motor space61. The sensor end21bis equipped with the resolver3(rotation angle sensor) for detecting a rotational angle of the shaft21. Hereinafter, along the direction of the core axis O of the shaft21, the side on which the first end21aof the shaft21is disposed is also referred to as “first side”, whereas the side on which the second end21bis disposed is also referred to as “second side”.

The resolver3includes a rotor3a, a stator3b, and output terminals (not illustrated). The resolver3is configured to output the rotational angle of the rotor3awith respect to the stator3bvia the output terminals to a controller (not shown). The rotor3aof the resolver3is fixed to the periphery of the sensor end21bof the shaft21in a rotatable manner with respect to the stator3b, and is rotatable together with the shaft21. The stator3bof the resolver3is disposed at the periphery of the rotor3a, and is fixed to the bulge portion42b.

Next, the configuration of the case40is to be described. As illustrated inFIGS. 1 and 2, the case40is a box-shaped member having a substantial cuboid appearance, and is constituted by a body41, a side lid42, and the top lid43. The body41, which is the main part of the case40, has an entire rectangular top face opened, and includes a partition wall41a(wall) extending along a horizontal plane at a height slightly lower than the height of the top edge of the body41. The internal space of the body41is vertically separated into two rooms61,62by the partition wall41a. The body41has a hole formed on a side wall at the first side along the shaft21, through which the hole the output end21aof the shaft21is disposed. The body41also has an opening shaped in a substantial circle and formed on a side wall at the second side along the shaft21. The hole and the opening of the body41are formed on respective parts of the side walls, the parts surrounding the lower room61(i.e., the motor space61).

The top lid43is a cover that closes the opened top face of the body41, and after being fixed to the top edge of the body41by bolts (not shown), composes a top wall of the case40. The side lid42is a cover that closes the opening of the body41, and after being fixed to the side wall on the second side of the body41by multiple (inFIG. 2, six) bolts7, composes a side wall of the case40in cooperation with the body41. The top lid43demarcates, in cooperation with the body41, the inverter space62that accommodates the inverter unit30, while the side lid42demarcates, in cooperation with the body41, the motor space61that accommodates the motor unit20.

As illustrated inFIG. 1, the case40has, in addition to the rooms61,62that respectively function as the motor space61and the inverter space62, the cooling passage70formed in the inside of the walls surrounding the rooms61,62.

The inverter space62of this embodiment is formed in a substantial cuboid. The power converter31, the capacitor32, and the control circuit33of the inverter unit30are disposed in the inverter space62, and are spaced apart from one another. The power converter31and the capacitor32are fixed on an upper face of the partition wall41athat separates the inverter space62from the motor space61, whereas the control circuit33is fixed above the power converter31and the capacitor32via a bracket(s) (not illustrated). In this embodiment, the power converter31is disposed on the second side along the shaft21, and the capacitor32is disposed on the first side along the shaft21.

The motor space61of this embodiment has a cylinder-like shape having an axis extending horizontally. The motor unit20is accommodated in the motor space61in such a manner that the core axis O of the motor unit20substantially coincides with the axis of the motor space61. The inner diameter of the motor space61is set slightly larger than the diameter of the motor unit20with the center at the core axis O. The length of the motor space61along the axis direction is set to the sum of the length of the space where the resolver3is disposed and the lengths of the rotor core24, the stator core23, and the coil22of the motor unit20along the axis direction. Namely, the motor space61provides a room61a(hereinafter, referred to as “surrounding space61a”) for accommodating the resolver3at the side on which the sensor end21bof the shaft21is received. The side lid42is placed in the surrounding space61a.

The side lid42has a circular plate portion42aformed in a disc shape, the bulge portion42bprotruding from the center of the circular plate portion42ain a substantial truncated cone shape, and a pump accommodating portion42cat a part of the outer circumference of the bulge portion42b. The circular plate portion42ahas a diameter slightly larger than the inner diameter of the motor space61. The circular plate portion42ais fixed to the body41from the outside of the motor space61, and closes the opening of the body41. In contrast, the bulge portion42band the pump accommodating portion42care both placed in the surrounding space61aof the motor space61.

The bulge portion42bis provided for pivotally supporting the shaft21and for fixing the resolver3, and is disposed coaxially with the core axis O. The bulge portion42bfixes thereto the stator3bof the resolver3and the bearing6that rotatably supports the shaft21. The bulge portion42bhas an outer diameter slightly larger than the outer diameter of the resolver3and sufficiently smaller than the inner diameter of the motor space61.

The surrounding space61aexists within the motor space61and at the periphery of the resolver3(specifically, between the outer circumference of the bulge portion42band the cylindrical inner wall of the body41). The surrounding space61ais an empty area generated by the disposition of the resolver3on the core axis O of the shaft21, and is a dead space. In order to utilize this dead space or the surrounding space61aeffectively, the pump50that forwards the coolant to the cooling passage70is disposed in the surrounding space61a. In this embodiment, the pump accommodating portion42cis placed in the surrounding space61a, and the pump50is disposed in the pump accommodating portion42c. Namely, the pump50is integrated in the case40.

As depicted inFIGS. 1 and 2, the pump50is an electric water pump, for example, and has a suctioning part52that draws the coolant into the pump50, a discharging part51that forwards the coolant drawn by the suctioning part52to the cooling passage70, a connection part53connected to an electric power source, and a flange part for attaching the pump50. The suctioning part52projects outside the case40, whereas the discharging part51protrudes from a side face of the pump50, and is disposed at an inner side with respect to the outer face of the case40(specifically, the discharging part51is disposed within the circular plate portion42aof the side lid42). The connection part53protrudes from the side face of the pump50towards the opposite side of the discharging part51. The flange54is an attaching portion for fixing the pump50to the case40. The flange54is shaped in a substantial ellipse, and is disposed perpendicularly to the side face of the pump50.

The pump accommodating portion42cis a recess dented from the circular plate portion42atoward the protruding direction of the bulge portion42b, and has a shape conforming to the outer shape of the pump50. The pump50is fixed to the pump accommodating portion42cby being partially fit into the pump accommodating portion42c. The pump accommodating portion42cis a continuation of the bulge portion42b, and is disposed at the upper portion of the surrounding space61a(i.e., the upper side of the bulge portion42b). The pump accommodating portion42cis adjoined to the inverter unit30via the partition wall41a. The pump accommodating portion42cis provided with an opening (not shown) that is located in correspondence to the discharging part51of the pump50and that composes an upstream end70aof the cooling passage70to be detailed later.

The pump50is fit into the pump accommodating portion42cfrom outside the case40, being oriented such that the longitudinal direction of the flange part54stands vertical, and is fixed to the circular plate portion42aby bolts2,2at two positions allocated vertically. With this arrangement, the suctioning part52is disposed outside the case40, and protrudes in a direction parallel to the core axis O. In contrast, the discharging part51and the connection part53are both accommodated in the pump accommodating portion42c. As illustrated inFIG. 3, the discharging part51is connected to the upstream end70aof the cooling passage70, while the suctioning part52is connected to the upstream passage4bof the cooling device4.

The cooling passage70functions as a flow path of the coolant (in other words, the cooling passage70is configured to let the coolant flow through the cooling passage70) in the inside of the motor apparatus1, and is formed in the inside of the walls including the partition wall41a. The cooling passage70of this embodiment takes the form of a single flow path being continuous from the upstream end70a(illustrated inFIG. 3) opening at the pump accommodating portion42cto a downstream end70bopening at a side face (i.e., the vertical side face parallel to the core axis O) of the body41as illustrated inFIG. 2. It should be noted that the position of the downstream end70bis not particularly limited.

The cooling passage70includes the first cooling part71for cooling the power converter31, the second cooling part72for cooling the capacitor32, and a third cooling part73for cooling the motor unit20. The first cooling part71takes a shape of a horizontal face extending in parallel with the bottom face of the power converter31in the inside of the partition wall41a, so as to conform to the surface shape of the power converter31. Similarly, the second cooling part72takes a shape of a horizontal face extending in parallel with the bottom face of the capacitor32in the inside of the partition wall41a, so as to conform to the surface shape of the capacitor32. In this embodiment, the first cooling part71and the second cooling part72are formed in the inside of the partition wall41aand close to the upper surface of the partition wall41a.

The third cooling part73is formed in a cylindrical shape extending in the inside of the wall surrounding the motor space61of the body41along the circumference of the motor unit20. As illustrated inFIG. 1, the upper portion of the third cooling part73is formed in the inside of the partition wall41a, close to the lower surface of the partition wall41a, and vertically below the first cooling part71and the second cooling part72.

The upstream end70aof the cooling passage70is positioned at a relatively high position in the case40because the pump50is disposed above the resolver3(i.e., at the upper portion of the surrounding space61a). This means that the coolant flowing into the upstream end70ahas relatively high potential energy, so that the coolant flows down into the cooling passage70with the help of gravity in addition to the discharging pressure applied by the pump50. Further, since the inverter unit30is arranged above the motor space61while the pump50is arranged above the resolver3, the distance between the pump50and the inverter unit30is shortened. Consequently, as shown inFIG. 3, the lengths (path lengths) L1, L2of the cooling passage70from the discharging part51of the pump50to the first cooling part71and the second cooling part72, respectively, are shortened.

The upstream end70aof the cooling passage70is connected to the discharging part51of the pump50, while the downstream end70bof the cooling passage70is connected to the downstream passage4cof the cooling device4. In the cooling passage70, the first cooling part71, the second cooling part72, and the third cooling part73are provided in this order from upstream to downstream. Namely, the first, the second, and the third cooling parts71,72,73are arranged in series, and the second cooling part72is provided downstream of the first cooling part71with respect to the discharging part51of the pump50(in other words, the second cooling part72is provided downstream of the first cooling part71when seen from the discharging part51). This makes the cooling passage70have the length L1from the discharging part51to the first cooling part71shorter than the length L2from the discharging part51to the second cooling part72. As a result, the coolant forwarded from the discharging part51reaches the first cooling part71before reaching the second cooling part72.

Thus, the coolant cooled by the radiator4ais forwarded to the cooling passage70by the pump50, and firstly cools the power converter31while flowing through the first cooling part71. The coolant secondly cools the capacitor32while flowing through the second cooling part72, thirdly cools the motor unit20while flowing through the third cooling part73, and then flows through the downstream end70bto be ejected to the downstream passage4c. As described above, the coolant immediately after passing the radiator4aand having a depressed temperature is supplied to the first cooling part71before being supplied to the second cooling part72and the third cooling part73. This enhances the cooling performance especially for the power converter31.

(1) According to the motor apparatus1described above, the surrounding space61acan be effectively utilized to save space since the pump50is disposed in the surrounding space61awithin the motor space61and at the periphery of the resolver3. The surrounding space61ais an empty area generated by the disposition of the resolver3on the shaft21of the motor unit20, and is the dead space in the motor space61. Since the motor apparatus1disposes the pump50in the dead space or the surrounding space61a, the motor apparatus1can reduce the waste of the space inside the case40, achieving an improvement in the space utilization of the interior of the case40.

Further, since the pump50is disposed in the case40accommodating the motor unit20and the inverter unit30, the coolant discharged by the pump50can be directly forwarded to the cooling passage70provided in the case40, resulting in reduction in resistance (flow resistance) that acts on the coolant. Accordingly, the motor apparatus1can enhance the cooling performance for the motor unit20and the inverter unit30. With this advantage, by reducing the size of the pump50, for example, it is possible to cut down the cost and the weight of the motor apparatus1while keeping the cooling performance equivalent to that of the conventional apparatus.

In addition, since the pump50is disposed in the case40accommodating the motor unit20and the inverter unit30, the number of components can be reduced as compared to a situation where the motor unit20, the inverter unit30, and the pump50are accommodated separately in respective (individual) cases. More specifically, it is possible to reduce the number of components including not only the case, but also brackets for attaching the case to the body of the vehicle, clips for attaching the pump50, cables or hoses between the motor unit20, the inverter unit30, and the pump50, and so on. This can reduce the weight of the motor apparatus1as well as the cost of the components, and can further reduce the assembly cost since assembling task is facilitated.

(2) According to the motor apparatus1described above, since the pump50is disposed above the resolver3(i.e., at the upper portion of the surrounding space61a) when installed in the vehicle, the pump50can be positioned relatively high. As a result, it is possible to elevate the potential energy of the coolant to be forwarded to the cooling passage70. This makes gravity promote the flow of the coolant when the coolant flows downwardly through the cooling passage70, for example, and thereby the cooling performance can be enhanced. Additionally, since the pump50can be positioned away from the road, the pump50can be protected from stones bouncing from the road.

(3) According to the motor apparatus1described above, since the inverter unit30is arranged to be adjacent to the pump50via the partition wall41ahaving the cooling passage70, the coolant forwarded to the cooling passage70by the pump50can be firstly directed toward the inverter unit30. This can enhance the cooling performance for the inverter unit30, which tends to have a temperature higher than a temperature of the motor unit20.

(4) According to the motor apparatus1described above, since the length L1of the cooling passage70from the discharging part51of the pump50to the first cooling part71is shorter than the length L2of the cooling passage70from the discharging part51to the second cooling part72, the resistance that acts on the coolant flowing from the discharging part51to the first cooling part71becomes smaller than the resistance that acts on the coolant flowing from the discharging part51to the second cooling part72. This can make the cooling performance for the power converter31higher than the cooling performance for the capacitor32. Accordingly, it is possible to enhance the cooling performance especially for the power converter31, which tends to have a temperature higher than a temperature of the capacitor32, so that the reliability of the inverter unit30can be enhanced.

Particularly, it is possible to shorten the length L1of the cooling passage70from the discharging part51to the first cooling part71because the pump50is disposed in the surrounding space61aand brings the discharging part51close to the upstream end70aof the cooling passage70. This can further reduce the resistance that acts on the coolant flowing from the discharging part51to the first cooling part71. As a result, the first cooling part71can be supplied with the coolant having a far lower temperature. Thus, the cooling performance for the inverter unit30can be enhanced.

(5) According to the motor apparatus1described above, since the second cooling part72is provided downstream of the first cooling part71with respect to the discharging part51of the pump50, it is possible to simplify the structure of the cooling passage70while enhancing the cooling performance for the inverter unit30.

(6) According to the motor apparatus1described above, the pump50can be disposed close to the inverter unit30since the inverter space62is arranged above the motor space61and the pump50is arranged above the resolver3(i.e., at the upper portion of the surrounding space61a). This can shorten the length L1of the cooling passage70from the discharging part51of the pump50to the first cooling part71and the length L2of the cooling passage70from the discharging part51to the second cooling part72. Accordingly, it is possible to lower the resistance that acts on the coolant flowing to the first and the second cooling parts71,72, as described above, resulting in enhancement in the cooling performance for both of the power converter31and the capacitor32.

The present invention should not be limited to the above embodiment, and may be modified in various ways within the subject matter of the embodiment. The configurations in the above embodiment may be selected as needed or combined appropriately.

Although the cooling medium exemplified in the above embodiment is the coolant, other cooling medium applicable to the motor apparatus1may be water, antifreeze liquid, cooling oil, or air, for example.

Further, the position, the structure, and the number of the pump50may be changed. The position of the pump50is not particularly limited to the upper portion of the surrounding space61a(above the resolver3), and may be any position within the surrounding space61a, such as a position lateral to or below the resolver3. Further, the above embodiment illustrates a structure where the pump50is fit into the pump accommodating portion42cand has the flange part54fixed to the circular plate portion42a. Alternatively, the pump50may omit the flange part54and have the body of the pump50fixed to the pump accommodating portion42c, for example. Conversely, the pump accommodating portion42cmay be omitted and the pump50may be fixed to the case40only at the flange part54. Further, two or more pumps may be provided to the surrounding space61a, for example, to enhance the cooling performance by increasing the discharging rate of the cooling medium to be forwarded to the cooling passage70.

The shape of the case40, and the shapes and the positions of the motor space61and the inverter space62are not limited to those of the above. The motor space and the inverter space may each be shaped in a substantial cuboid, or may be aligned horizontally, for example. Further, the above arrangement, of each element31-33of the inverter unit30is merely an example, and may be modified. For example, the power converter31may be disposed on the side of the output end21aof the shaft21while the capacitor32may be disposed on the side of the sensor end21b, or the power converter31and the capacitor32may be aligned in a direction that crosses the core axis O. Alternatively, two or three inverter spaces may be provided in the case40to accommodate one or two of the power converter31, the capacitor32, and the control circuit33individually.

Although the above embodiment illustrates the motor unit20disposed such that the core axis O of the shaft21extends horizontally, the extending direction of the core axis O of the shaft21is not limited to a horizontal direction, and may be changed.

Further, the rotation angle sensor fixed to the shaft of the motor apparatus is not limited to the above resolver3, and may alternatively be a rotary encoder, for example.

REFERENCE SIGNS LIST

71first cooling part

72second cooling part

73third cooling part