Patent Description:
PTL <NUM> discloses an industrial unmanned helicopter. This industrial unmanned helicopter includes a first main rotor, a second main rotor, a drive device that rotationally drives the second main rotor, and a drive transmission member that transmits a rotational force of the second main rotor to the first main rotor by reversing a rotational direction.

In the industrial unmanned helicopter described above, the driving force transmission member is positioned between the first main rotor and the second main rotor in a rotation axis direction in which the rotation axis of the first main rotor extends. Therefore, there is a problem that a part including the first main rotor, the second main rotor, the drive device, and the driving force transmission member tends to become large in the rotation axis direction in which the rotation axis of the first main rotor extends. PTL <NUM> discloses a jam-tolerant electromechanical linear actuator having a contra-rotating axial flux permanent magnet (PM) motor having a first and second rotor shafts in a motor housing. The actuator also includes a first speed reduction mechanism operably coupled to the first rotor shaft and a second speed reduction mechanism operably coupled to the second rotor shaft; a first output shaft operably coupled to a output of the first speed reduction mechanism and a second output shaft operably coupled to an output of the second speed reduction mechanism. PTL <NUM> discloses a rotary propulsion system includes a fan arranged along a rotation axis, an electric motor having windings and a permanent magnet arranged along the rotation axis and operatively connected to the fan, and a reduction gear set. The reduction gear set extends about the rotation axis and couples the electric motor to the fan. PTL <NUM> discloses a marine vessel propulsion device including an electric motor, propeller means driven by the electric motor and gear means drivingly connecting the electric motor to the propeller means.

PTL <NUM>: Unexamined <CIT>. PTL <NUM>: <CIT>; PTL <NUM>: <CIT>; PTL <NUM>: <CIT>.

The present disclosure has been made in view of the above circumstances. An object of the present disclosure is to provide a motor unit capable of suppressing an increase in size of the motor unit in a direction in which an axial center of a rotor extends, and a flying object including the motor unit.

A motor unit according to one aspect of the present disclosure includes a stator, a rotor, and a gear unit. The rotor is positioned around the stator and rotates by a magnetic force generated in the stator to generate a rotational force of a first rotary vane. The gear unit includes a plurality of gears, and converts a rotational force generated by the rotor to rotate a second rotary vane in an inverse direction to a rotation direction of the first rotary vane. At least a part of the plurality of gears are positioned inside the stator.

It is preferable that half or more of the plurality of gears are positioned inside the stator.

The motor unit may further include a first shaft that transmits the rotational force generated by the rotor to the first rotary vane, and a second shaft that transmits the rotational force generated by the gear unit to the second rotary vane. It is preferable that the first shaft is formed in a tubular shape, is positioned around the second shaft, and is rotatably supported by the second shaft.

It is preferable that the plurality of gears include a gear connected to the rotor.

It is preferable that the gear unit includes, as the plurality of gears, a first bevel gear that rotates in a rotation direction of the rotor by the rotational force generated by the rotor, a second bevel gear that meshes with the first bevel gear, and a third bevel gear that meshes with the second bevel gear and rotates in a direction opposite to the first bevel gear to generate a rotational force of the second rotary vane.

It is preferable that the motor unit further includes the first shaft that transmits the rotational force generated by the rotor to the first rotary vane, and the second shaft that transmits the rotational force generated by the gear unit to the second rotary vane. It is preferable that the gear unit includes, as the plurality of bevel gears, the first bevel gear that rotates in a rotation direction of the rotor by the rotational force generated by the rotor, the second bevel gear that meshes with the first bevel gear, and the third bevel gear that meshes with the second bevel gear and rotates in a direction opposite to the first bevel gear to generate a rotational force of the second rotary vane, the first shaft rotates integrally with the first bevel gear, and the second shaft rotates integrally with the third bevel gear.

It is preferable that the first bevel gear is a bevel gear connected to the rotor.

It is preferable that the motor unit includes: a lubricant that lubricates a mesh part of the plurality of gears; a cover member that rotates together with the rotor; an accommodating part that is positioned inside the stator, includes an opening covered by the cover member, and accommodates the plurality of gears and the lubricant; and a magnetic fluid that seals between the accommodating part and the cover member.

It is preferable that the motor unit further includes the first rotary vane and the second rotary vane.

A flying object according to another aspect of the present disclosure includes a body and the motor unit attached to this body.

The motor unit and the flying object according to the above aspects can suppress an increase in size in the axial center direction of the rotor of a motor unit.

Hereinafter, a motor unit and a flying object of an exemplary embodiment of the present disclosure will be described.

<FIG> is a perspective view of motor unit <NUM> according to an exemplary embodiment. <FIG> is a perspective cross-sectional view of motor unit <NUM>. Motor unit <NUM> is a contra-rotating rotor that rotates coaxially arranged two rotary vanes <NUM>, <NUM> in inverse directions to each other. For example, as illustrated in <FIG>, motor unit <NUM> is mounted on flying objects <NUM>, <NUM>, <NUM> as a rotor or a propeller, and is used to obtain propulsion force of flying objects <NUM>, <NUM>, <NUM>. <FIG> is a top view of flying object <NUM> including motor unit <NUM>. <FIG> is a perspective view of another flying object <NUM> including motor unit <NUM>. <FIG> is a perspective view of still another flying object <NUM> including motor unit <NUM>.

As illustrated in <FIG> and <FIG>, motor unit <NUM> includes motor <NUM>, first rotary vane <NUM>, second rotary vane <NUM>, and gear unit <NUM>.

Motor <NUM> solely generates the driving force of first rotary vane <NUM> and the driving force of second rotary vane <NUM>. That is, motor <NUM> is shared as a drive source of first rotary vane <NUM> and a drive source of second rotary vane <NUM>.

Motor <NUM> is a brushless motor. Motor <NUM> includes stator <NUM> and rotor <NUM> that rotates by a magnetic force generated in stator <NUM>. Motor <NUM> is an outer rotor type motor in which a magnet included in rotor <NUM> is positioned around stator <NUM>.

Rotor <NUM> generates a rotational force of first rotary vane <NUM>. The rotational force of rotor <NUM> is transmitted to first rotary vane <NUM> without changing the orientation of the force. Due to this, first rotary vane <NUM> rotates in the same direction as rotor <NUM> together with rotor <NUM> about axial center <NUM>, which is the rotation center of rotor <NUM>, and generates a propulsion force in one direction parallel to axial center <NUM> of rotor <NUM>.

The rotational force of rotor <NUM> is transmitted to second rotary vane <NUM> via gear unit <NUM>. Gear unit <NUM> converts the rotational force of rotor <NUM> to generate a rotational force for rotating second rotary vane <NUM> in an inverse direction to the rotation direction of first rotary vane <NUM>. Due to this, second rotary vane <NUM> rotates in an inverse direction to the rotation direction of first rotary vane <NUM> about axial center <NUM> of rotor <NUM>, and generates a propulsion force in one direction. In this case, first rotary vane <NUM> and second rotary vane <NUM> rotate simultaneously, and first rotary vane <NUM> and second rotary vane <NUM> generate a propulsion force in the same direction. Hereinafter, unless otherwise specified, motor unit <NUM> will be described assuming that a direction in which axial center <NUM> of rotor <NUM> extends is an up-and-down direction, where a propulsion direction (a direction in which first rotary vane <NUM> and second rotary vane <NUM> generate a propulsion force) is up, and an inverse direction to the propulsion force direction is down. The direction used in the present disclosure does not limit the direction when motor unit <NUM> is in use.

As illustrated in <FIG>, motor unit <NUM> further includes base <NUM>. Base <NUM> includes base plate <NUM> having a flat plate shape whose thickness direction is parallel to the up-and-down direction. Base plate <NUM> is formed in a circular shape as viewed from the up-and-down direction.

Stator <NUM> is along an upper surface, which is a surface on one side in the thickness direction of base plate <NUM>. Stator <NUM> is fixed to base plate <NUM>. Stator <NUM> is fixed to base plate <NUM> by, for example, a fixing tool such as a screw. Stator <NUM> is formed in an annular shape as viewed from the up-and-down direction. Stator <NUM> is formed in an annular shape concentric with base plate <NUM>. Stator <NUM> includes, for example, a stator core and a stator coil wound around the stator core. The stator generates a magnetic force for rotating rotor <NUM> by energizing the stator coil.

Motor unit <NUM> further includes two shafts <NUM>, <NUM>. One shaft <NUM> of two shafts <NUM>, <NUM> transmits the rotational force of rotor <NUM> to first rotary vane <NUM>, and rotates first rotary vane <NUM>. Other shaft <NUM> transmits, to second rotary vane <NUM>, the rotational force in the inverse direction to the rotation direction of rotor <NUM> output from gear unit <NUM>, and rotates second rotary vane <NUM> in the inverse direction to first rotary vane <NUM>. Hereinafter, shaft <NUM> is called first shaft <NUM>, and shaft <NUM> is called second shaft <NUM>.

Second shaft <NUM> is formed in a columnar shape extending in the up-and-down direction. Second shaft <NUM> is rotatably attached to base plate <NUM>. Base <NUM> further includes bearing <NUM> attached to the center of base plate <NUM>. The lower end of second shaft <NUM> is restricted in movement in the up-and-down direction by bearing <NUM> and is rotatably supported about the central axis of second shaft <NUM>. Base plate <NUM> may have a part that restricts the movement of second shaft <NUM> in the up-and-down direction and rotatably supports second shaft <NUM> about the central axis of second shaft <NUM>. In this case, bearing <NUM> can be omitted.

Rotor <NUM> is formed in a covered cylindrical shape (cup shape) opening downward. Rotor <NUM> covers stator <NUM> from above in a non-contact state. Rotor <NUM> includes lid <NUM> and peripheral wall portion <NUM>. Lid <NUM> is positioned above stator <NUM>. Lid <NUM> is formed in a plate shape whose thickness direction is parallel to the up-and-down direction. Lid <NUM> opposes the upper surface of stator <NUM> with a gap interposed therebetween.

Lid <NUM> has center <NUM>, peripheral edge <NUM>, and a plurality of connecting parts <NUM>. Center <NUM> is positioned at the center of lid <NUM> as viewed from the up-and-down direction. Center <NUM> is positioned above a space formed inside annular stator <NUM>. Peripheral edge <NUM> is formed in an annular shape as viewed from the up-and-down direction. Peripheral edge <NUM> is positioned around center <NUM> at an interval from center <NUM>. The plurality of connecting parts <NUM> are arranged at intervals in a circumferential direction of rotor <NUM> (circumferential direction of peripheral edge <NUM>) between center <NUM> and peripheral edge <NUM>. The plurality of connecting parts <NUM> connect center <NUM> and peripheral edge <NUM>.

Lid <NUM> is provided with a plurality of holes <NUM> arranged in the circumferential direction of rotor <NUM>. Each hole <NUM> is formed between connecting parts <NUM> adjacent to each other in the circumferential direction of rotor <NUM>. Each hole <NUM> penetrates lid <NUM> in the up-and-down direction. The plurality of holes <NUM> cause the space above lid <NUM> and the space inside rotor <NUM> (space surrounded by peripheral wall portion <NUM>) positioned below lid <NUM> to communicate with each other. Therefore, the heat generated in stator <NUM> is less likely to be accumulated inside rotor <NUM>.

Peripheral wall portion <NUM> of rotor <NUM> protrudes downward (stator <NUM> side) from peripheral edge <NUM> of lid <NUM>. Peripheral wall portion <NUM> is formed in a cylindrical shape in which the direction in which the central axis extends is parallel to the up-and-down direction. The inner peripheral surface of peripheral wall portion <NUM> opposes the outer peripheral surface of stator <NUM> with a slight gap interposed therebetween.

Peripheral wall portion <NUM> includes a plurality of magnets arranged in the circumferential direction of rotor <NUM>, for example, or one magnet continuous in the circumferential direction of rotor <NUM>. The plurality of magnets are arranged such that magnetic poles on stator <NUM> side of two adjacent magnets are different, for example. For example, one magnet is magnetized such that the magnetic poles positioned on stator <NUM> side alternate in the circumferential direction of rotor <NUM>. Rotor <NUM> rotates about axial center <NUM> of rotor <NUM> by magnetic attraction force and repulsive force generated between a magnetic field formed by stator <NUM> and a plurality of or one magnet. The center of lid <NUM> of rotor <NUM> (the center of center <NUM>) is provided with fitting hole <NUM> penetrating in the up-and-down direction.

First shaft <NUM> is formed in a cylindrical shape extending in the up-and-down direction. First shaft <NUM> is positioned around second shaft <NUM>. First shaft <NUM> is supported by second shaft <NUM> rotatably about the central axis of second shaft <NUM>. First shaft <NUM> penetrates lid <NUM> in the up-and-down direction through fitting hole <NUM> of rotor <NUM>. First shaft <NUM> is fixed to lid <NUM> of rotor <NUM>. First shaft <NUM> is fixed to lid <NUM> of rotor <NUM>, for example, by being press-fitted into fitting hole <NUM>. A means for fixing first shaft <NUM> to rotor <NUM> is not limited, and for example, first shaft <NUM> may be fixed by rotor <NUM> by adhesion or the like.

Rotor <NUM> is rotatably supported by second shaft <NUM> via first shaft <NUM>. The rotation center of rotor <NUM> is defined by first shaft <NUM> and second shaft <NUM>. Rotor <NUM> rotates about second shaft <NUM> together with first shaft <NUM>. Axial center <NUM>, which is the rotation center of rotor <NUM>, overlaps the central axis of first shaft <NUM> and the central axis of second shaft <NUM>.

First shaft <NUM> has protrusion <NUM> protruding upward relative to center <NUM> of rotor <NUM>. First rotary vane <NUM> is coupled to protrusion <NUM>.

As illustrated in <FIG>, first rotary vane <NUM> includes rotation part <NUM> and a plurality of blades <NUM>. Rotation part <NUM> is fixed to protrusion <NUM> of first shaft <NUM>. Rotation part <NUM> rotates about the central axis of first shaft <NUM> together with first shaft <NUM>.

First rotary vane <NUM> has a total of two blades <NUM>. Each blade <NUM> is a plate-shaped vane extending in a direction intersecting the up-and-down direction. A base end (one end in the length direction) of each blade <NUM> is coupled to rotation part <NUM>. Each blade <NUM> protrudes from rotation part <NUM> in a direction intersecting the up-and-down direction. When rotor <NUM> rotates about axial center <NUM> illustrated in <FIG>, each blade <NUM> rotates about the central axis of second shaft <NUM> together with first shaft <NUM> and rotation part <NUM>. This causes first rotary vane <NUM> to generate an upward propulsion force.

The number of blades <NUM> included in first rotary vane <NUM> is not limited. For example, first rotary vane <NUM> may have only one blade <NUM> or may include three or more of them. Motor unit <NUM> needs not include first rotary vane <NUM>. In this case, when flying objects <NUM>, <NUM>, <NUM> are assembled, it is only required to attach separately prepared first rotary vane <NUM> to first shaft <NUM>.

As illustrated in <FIG>, base <NUM> includes accommodating part <NUM> that accommodates gear unit <NUM> inside stator <NUM>. A part of accommodating part <NUM> is configured by gear case <NUM>. Gear case <NUM> is formed in a cylindrical shape whose central axis direction is parallel to the up-and-down direction. Gear case <NUM> is formed in a cylindrical shape concentric with stator <NUM>. Gear case <NUM> is positioned inside stator <NUM> and is positioned around first shaft <NUM>. Gear case <NUM> has first opening <NUM> formed at a lower end of gear case <NUM> and second opening <NUM> formed at an upper end of gear case <NUM>.

The lower end surface of gear case <NUM> is along the upper surface of base plate <NUM>. The upper end surface of gear case <NUM> is along the lower surface of center <NUM> of rotor <NUM>. However, gear case <NUM> is not in contact with rotor <NUM>. Gear case <NUM> is fixed to base plate <NUM>. Gear case <NUM> is fixed to base plate <NUM> with, for example, a fixing tool such as a screw.

First opening <NUM> of gear case <NUM> is covered with a center of base plate <NUM>. The center, which is a part of base plate <NUM>, constitutes a bottom of accommodating part <NUM>. Gear case <NUM> constitutes a peripheral wall portion protruding upward from the bottom of accommodating part <NUM>. Second opening <NUM> of gear case <NUM> is covered with center <NUM>, which is a part of rotor <NUM>.

Accommodating part <NUM> further includes holding member <NUM>. Holding member <NUM> holds magnetic fluid <NUM> (see <FIG>) described below. Holding member <NUM> is attached to the inner peripheral surface of second opening <NUM> of gear case <NUM>. Accommodating part <NUM> includes gear case <NUM>, a center of base plate <NUM>, and holding member <NUM>. Holding member <NUM> is formed in an annular shape as viewed from the up-and-down direction. Inside of holding member <NUM> is provided with opening <NUM> penetrating in the up-and-down direction is formed.

Accommodating part <NUM> has accommodation space <NUM> surrounded by gear case <NUM>, center <NUM> of base plate <NUM>, and holding member <NUM>. Accommodation space <NUM> is opened upward through opening <NUM> of holding member <NUM>.

Gear unit <NUM> is positioned in accommodation space <NUM>. Gear unit <NUM> includes bevel gears <NUM>, <NUM>, <NUM>, which are a plurality of gears. Gear unit <NUM> includes, as the plurality of bevel gears, first bevel gear <NUM>, a plurality of second bevel gears <NUM>, and third bevel gear <NUM>. First bevel gear <NUM>, the plurality of second bevel gears <NUM>, and third bevel gear <NUM> are each made of iron, for example. Each of first bevel gear <NUM>, the plurality of second bevel gears <NUM>, and third bevel gear <NUM> is not limited to iron. First bevel gear <NUM>, the plurality of second bevel gears <NUM>, and third bevel gear <NUM> may each be formed of a metal other than iron, or may be formed of a material other than metal.

First bevel gear <NUM> is positioned below center <NUM> of rotor <NUM>. First bevel gear <NUM> is positioned in opening <NUM> of accommodating part <NUM> (the upper end of accommodation space <NUM>). The center of first bevel gear <NUM> is provided with hole <NUM> penetrating first bevel gear <NUM> in the up-and-down direction. First shaft <NUM> penetrates first bevel gear <NUM> in the up-and-down direction through hole <NUM> of first bevel gear <NUM>.

The upper end of first bevel gear <NUM> is positioned between holding member <NUM> of accommodating part <NUM> and first shaft <NUM>. The upper end of first bevel gear <NUM> covers opening <NUM> of accommodating part <NUM>. That is, first bevel gear <NUM> constitutes a cover member that covers opening <NUM> of accommodating part <NUM>. The cover member is not limited to first bevel gear <NUM>. The cover member may be another member that rotates together with rotor <NUM>. The "cover member that rotates together with rotor <NUM>" in the present disclosure also includes a part of rotor <NUM>. Therefore, the cover member may be a member other than first bevel gear <NUM> or may be a part of rotor <NUM>.

First bevel gear <NUM> is fixed to center <NUM> in a state of being in contact with the lower surface of center <NUM> of rotor <NUM>. First bevel gear <NUM> is connected to rotor <NUM>. First bevel gear <NUM> rotates together with rotor <NUM> about axial center <NUM> of rotor <NUM> in the same direction as the rotation direction of rotor <NUM>. The lower surface of first bevel gear <NUM> is provided with a plurality of teeth arranged in the circumferential direction of first bevel gear <NUM>. First bevel gear <NUM> is a member different from rotor <NUM>. However, first bevel gear <NUM> may be a part of rotor <NUM>. That is, first bevel gear <NUM> may be formed integrally with rotor <NUM>. First bevel gear <NUM> may be fixed to first shaft <NUM>. In this case, first bevel gear <NUM> may be fixed to both rotor <NUM> and first shaft <NUM>. First bevel gear <NUM> may be fixed only to first shaft <NUM>. For example, first bevel gear <NUM> is fixed to first shaft <NUM> by press-fitting first shaft <NUM> into hole <NUM>. In this case, first shaft <NUM> rotates integrally with rotor <NUM>. A means for fixing first bevel gear <NUM> to first shaft <NUM> is not limited. For example, first bevel gear <NUM> may be fixed to first shaft <NUM> by adhesion or the like.

The plurality of second bevel gears <NUM> are positioned below first bevel gear <NUM>. The plurality of second bevel gears <NUM> are arranged at intervals in the circumferential direction of first bevel gear <NUM>. Gear unit <NUM> includes a total of three second bevel gears <NUM>. Base <NUM> further includes a plurality of spindles <NUM> that respectively support the plurality of second bevel gears <NUM>. Each spindle <NUM> is attached to gear case <NUM>. Each spindle <NUM> protrudes inward from gear case <NUM>. Second bevel gears <NUM> are each attached to corresponding spindle <NUM> rotatably about a rotation shaft orthogonal to axial center <NUM> of rotor <NUM>.

The outer peripheral surface of each of second bevel gears <NUM> is provided with a plurality of teeth arranged in the circumferential direction of second bevel gear <NUM>. A part of the plurality of teeth of each of second bevel gears <NUM> mesh with a part of the plurality of teeth of first bevel gear <NUM>. When first bevel gear <NUM> rotates about axial center <NUM> of rotor <NUM>, each of second bevel gears <NUM> rotates about corresponding spindle <NUM>. Spindles <NUM> may each be attached rotatably to gear case <NUM>. In this case, each of second bevel gears <NUM> may be fixed in a non-rotatable manner with respect to corresponding spindle <NUM>. The number of second bevel gears <NUM> included in gear unit <NUM> is not limited. For example, gear unit <NUM> may include only one, only two, or four or more second bevel gears <NUM>.

Third bevel gear <NUM> is positioned below the plurality of second bevel gears <NUM> and first shaft <NUM>. Third bevel gear <NUM> is positioned at the lower end of accommodation space <NUM> of accommodating part <NUM>. The center of third bevel gear <NUM> is provided with fitting hole <NUM> penetrating third bevel gear <NUM> in the up-and-down direction. Second shaft <NUM> penetrates third bevel gear <NUM> in the up-and-down direction through fitting hole <NUM> of third bevel gear <NUM>. Third bevel gear <NUM> is fixed to second shaft <NUM>. Third bevel gear <NUM> rotates integrally with second shaft <NUM> together with second shaft <NUM>. For example, third bevel gear <NUM> is fixed to second shaft <NUM> by press-fitting second shaft <NUM> into fitting hole <NUM>. A means for fixing third bevel gear <NUM> to second shaft <NUM> is not limited. For example, third bevel gear <NUM> may be fixed to second shaft <NUM> by adhesion or the like.

The upper surface of third bevel gear <NUM> is provided with a plurality of teeth arranged in the circumferential direction of third bevel gear <NUM>. A part of the plurality of teeth of third bevel gear <NUM> mesh with a part of the plurality of teeth of each second bevel gear <NUM>. When first bevel gear <NUM> rotates and each of the second bevel gears rotates about a rotation axial center orthogonal to axial center <NUM> of rotor <NUM>, third bevel gear <NUM> rotates together with second shaft <NUM> about the central axis of second shaft <NUM> in an inverse direction to the rotation direction of first bevel gear <NUM>.

First bevel gear <NUM>, the plurality of second bevel gears <NUM>, and third bevel gear <NUM> are each a straight bevel gear in which tooth traces extend linearly. However, the present invention is not limited to this. For example, first bevel gear <NUM>, the plurality of second bevel gears <NUM>, and third bevel gear <NUM> may each be a spiral bevel gear in which tooth traces are curved in a curved shape in order to suppress vibration and noise. The bevel gear included in gear unit <NUM> is not limited to a bevel gear. The bevel gear included in gear unit <NUM> may be a gear other than the bevel gear.

Second shaft <NUM> has protrusion <NUM> protruding upward relative to first shaft <NUM>. Second rotary vane <NUM> is coupled to protrusion <NUM>. Second rotary vane <NUM> is positioned above first rotary vane <NUM>. Second rotary vane <NUM>, first rotary vane <NUM>, rotor <NUM>, and stator <NUM> are arranged in this order in the up-and-down direction.

Second rotary vane <NUM> includes rotation part <NUM> and a plurality of blades <NUM>. Rotation part <NUM> is fixed to protrusion <NUM> of second shaft <NUM>. Rotation part <NUM> rotates about the central axis of second shaft <NUM> together with second shaft <NUM>.

Second rotary vane <NUM> has a total of two blades <NUM>. Each blade <NUM> is a plate-shaped vane extending in a direction intersecting the up-and-down direction. A base end (one end in the length direction) of each blade <NUM> is coupled to rotation part <NUM>. Each blade <NUM> protrudes in a direction intersecting the up-and-down direction from rotation part <NUM>. When rotor <NUM> rotates about axial center <NUM>, each blade <NUM> rotates about the central axis of second shaft <NUM> together with third bevel gear <NUM>, second shaft <NUM>, and rotation part <NUM>. This makes second rotary vane <NUM> generate an upward propulsion force.

The number of blades <NUM> included in second rotary vane <NUM> is not limited. For example, second rotary vane <NUM> may have only one blade <NUM> or may include three or more of them. Motor unit <NUM> needs not include second rotary vane <NUM>. In this case, when flying objects <NUM>, <NUM>, <NUM> are assembled, it is only required to attach separately prepared second rotary vane <NUM> to second shaft <NUM>.

Motor unit <NUM> further includes a lubricant that lubricates the mesh parts of the plurality of bevel gears <NUM>, <NUM>, <NUM>. The lubricant is accommodated in accommodating part <NUM> together with the plurality of bevel gears <NUM>, <NUM>, <NUM>. The lubricant adheres to the plurality of bevel gears <NUM>, <NUM>, <NUM>. The lubricant is, for example, lubricating oil or grease.

<FIG> is an enlarged cross-sectional view of a part indicated by A1 in <FIG>. Motor unit <NUM> further includes magnetic fluid (magnetic fluid seal) <NUM> illustrated in <FIG>. Magnetic fluid <NUM> is a liquid containing a base liquid and a large number of magnetic particles dispersed in the base liquid. The magnetic particles are, for example, manganese zinc ferrite, iron oxide-based fine particles, spinel ferrite, γ-hematite, or the like. The base liquid is, for example, a hydrocarbon-based oil, a fluorine-based oil, water, or the like. Magnetic fluid <NUM> seals between accommodating part <NUM> and first bevel gear (cover member) <NUM> covering opening <NUM> of accommodating part <NUM>. The lubricant accommodated in accommodating part <NUM> is suppressed from coming out from between gear case <NUM> and first bevel gear <NUM>.

Magnetic fluid <NUM> is held by holding member <NUM> of accommodating part <NUM>. Holding member <NUM> includes magnet <NUM> and a pair of magnetic pole pieces <NUM>, <NUM>. Magnet <NUM> is a plate formed in an annular shape as viewed from the up-and-down direction. The outer peripheral end surface of magnet <NUM> is along the inner peripheral surface of second opening <NUM>. Each of the pair of magnetic pole pieces <NUM>, <NUM> is formed of a soft magnetic material. Magnetic pole pieces <NUM>, <NUM> are each an iron plate formed in an annular shape as viewed from the up-and-down direction. The pair of magnetic pole pieces <NUM>, <NUM> extend along the upper surface and the lower surface, respectively, of magnet <NUM>. The outer peripheral end surface of each of magnetic pole pieces <NUM>, <NUM> is along the inner peripheral surface of second opening <NUM>.

The inner end of each of magnetic pole pieces <NUM>, <NUM> protrudes inward relative to the inner peripheral surface of magnet <NUM>. The inner peripheral end surface of magnet <NUM> and the inner peripheral end surface of each of magnetic pole pieces <NUM>, <NUM> oppose the outer peripheral surface of first bevel gear <NUM>. Opening <NUM> of accommodating part <NUM> includes a hole formed inside magnet <NUM> and a hole formed inside each of magnetic pole pieces <NUM>, <NUM>. First bevel gear <NUM> is positioned in opening <NUM>.

Holding member <NUM> forms a magnetic circuit with magnet <NUM>, the pair of magnetic pole pieces <NUM>, <NUM>, and first bevel gear <NUM> made of iron. The magnetic circuit has, as a magnetic gap, gap <NUM> between the inner peripheral end surfaces of the pair of magnetic pole pieces <NUM>, <NUM> and the outer peripheral surface of first bevel gear <NUM>. The magnetic circuit holds magnetic fluid <NUM> in a state of being filled in gap <NUM>. Magnetic fluid <NUM> held in this manner seals between the inner peripheral surface of opening <NUM> of accommodating part <NUM> and the outer peripheral surface of first bevel gear <NUM>. This suppresses the lubricant in accommodating part <NUM> from coming out of accommodating part <NUM>. First bevel gear <NUM> may be formed of a soft magnetic material other than iron. The bevel gear other than first bevel gear <NUM> of gear unit <NUM> may be formed of a material other than the soft magnetic material. Magnetic fluid <NUM> may be held by a means other than holding member <NUM>. Motor unit <NUM> needs not include magnetic fluid <NUM> and holding member <NUM>.

In the plurality of bevel gears <NUM>, <NUM>, <NUM> included in gear unit <NUM> illustrated in <FIG>, only the upper end of first bevel gear <NUM> connected to rotor <NUM> is positioned slightly outside relative to stator <NUM> in the up-and-down direction. All parts of the plurality of bevel gears <NUM>, <NUM>, <NUM> other than the upper end of first bevel gear <NUM> are positioned inside stator <NUM>. That is, most of the plurality of bevel gears <NUM>, <NUM>, <NUM> are positioned inside stator <NUM>. The term "most" means half or more.

Therefore, for example, as compared with a case where the plurality of bevel gears <NUM>, <NUM>, <NUM> are positioned upward or downward relative to stator <NUM>, an increase in size of motor unit <NUM> in the up-and-down direction is suppressed. In this case, first rotary vane <NUM> and second rotary vane <NUM> can be disposed near stator <NUM> and rotor <NUM> in the up-and-down direction. Therefore, the length in the up-and-down direction of each of shafts <NUM>, <NUM> can be shortened. Moreover, it is possible to suppress vibration of the upper end of each shafts <NUM>, <NUM> during rotation of rotor <NUM>. Therefore, it is possible to suppress each shafts <NUM>, <NUM> from deforming due to wind or the like. For example, it is not necessary to enhance the strength of shafts <NUM>, <NUM> by thickening shafts <NUM>, <NUM>. It is also not necessary to enhance the strength of the part supporting each of shafts <NUM>, <NUM> such as bearing <NUM>. Vibration of each of blades <NUM>, <NUM> during flight of flying objects <NUM>, <NUM>, <NUM> is also suppressed. Therefore, during flight of flying objects <NUM>, <NUM>, <NUM>, data can be accurately acquired by the sensors included in the flight controllers of flying objects <NUM>, <NUM>, <NUM>. It becomes also possible to reduce the size of a cushion for protecting control devices of flying objects <NUM>, <NUM>, <NUM>, such as sponge and rubber, or to omit the cushion.

Since gear unit <NUM> is disposed in a space formed inside annular stator <NUM>, it is also possible to suppress an increase in size of motor unit <NUM> in a direction orthogonal to the up-and-down direction. Since stator <NUM> exists around gear unit <NUM>, it is also possible to prevent dirt, dust, insects, or the like from entering the inside of stator <NUM> in which gear unit <NUM> exists.

The plurality of bevel gears <NUM>, <NUM>, <NUM> included in gear unit <NUM> may be entirely disposed inside stator <NUM>. A part of the plurality of bevel gears <NUM>, <NUM>, <NUM> included in gear unit <NUM> may be disposed downward relative to stator <NUM>. That is, at least a part of the plurality of bevel gears <NUM>, <NUM>, <NUM> is only required to be disposed inside stator <NUM>.

<FIG> illustrates flying object <NUM> including motor unit <NUM>. Flying object <NUM> is an unmanned aircraft capable of autonomous flight or flight by remote control. Flying object <NUM> is large and can be used for agrochemical spraying, transportation, and the like. The size of flying object <NUM> is not limited. The flying object may be a manned flying object.

Flying object <NUM> is a multi-copter. Flying object <NUM> includes body <NUM> and a plurality of rotors. Flying object <NUM> includes a plurality of motor units <NUM> and a plurality of single rotors <NUM> as the plurality of rotors. That is, flying object <NUM> includes motor unit <NUM> used as a contra-rotating rotor and single rotor <NUM> that rotates only one rotary vane <NUM>. Specifically, flying object <NUM> includes four motor units <NUM> and two single rotors <NUM>. The number of motor units <NUM> and the number of single rotors <NUM> included in flying object <NUM> are not limited.

Body <NUM> includes housing <NUM>, a flight controller, a power source, and a plurality of arms <NUM>. The flight controller and the power source are built in housing <NUM>, for example. The flight controller and the power source may be attached to the outer surface of housing <NUM>. Body <NUM> includes, as the plurality of arms <NUM>, the same number of arms <NUM> as the number of rotors included in flying object <NUM> (the number obtained by adding the number of motor units <NUM> and the number of single rotors <NUM>). Arms <NUM> each protrude in a direction intersecting the up-and-down direction from housing <NUM>. Each arm <NUM> is attached with motor unit <NUM> or single rotor <NUM>. Each motor unit <NUM> is attached to arm <NUM> such that first rotary vane <NUM> and second rotary vane <NUM> are positioned above stator <NUM>, and the propulsion force generated by each of first rotary vane <NUM> and second rotary vane <NUM> acts upward. Each single rotor <NUM> is also attached to arm <NUM> such that the propulsion force generated by rotary vane <NUM> acts upward.

The flight controller includes, for example, a control unit and a plurality of sensors. The control device is, for example, a microcontroller, and includes a processor and a memory as hardware. The control device controls the flight of flying object <NUM> by a processor executing a program recorded in a memory. The plurality of sensors can include an acceleration sensor, a gyro sensor, a geomagnetic sensor, an atmospheric pressure sensor (altimeter), a global positioning system (GPS) sensor, and an image sensor. On the basis of data acquired by the plurality of sensors, the control device controls the plurality of motor units <NUM> and the plurality of single rotors <NUM>, and controls a flight direction, a flight speed, a flight attitude, and the like of flying object <NUM>.

Control of each motor unit <NUM> by the flight controller is performed, for example, via an electric speed controller (ESC). The ESC may be included in body <NUM>, or may be included in motor unit <NUM> or single rotor <NUM>. The power source supplies electric power to the flight controller, the plurality of motor units <NUM>, the plurality of single rotors <NUM>, and the like. The power source is, for example, a battery such as a lithium polymer battery, a lithium ion battery, a nickel hydrogen battery, or the like. Body <NUM> may further include a remote controller or a camera device. Body <NUM> may further include a communication device that communicates with an external device such as a personal computer.

<FIG> illustrates another flying object <NUM> including motor unit <NUM> of the present exemplary embodiment. Flying object <NUM> has elements common to flying object <NUM> illustrated in <FIG>. For this reason, the description of matters of flying object <NUM> overlapping with flying object <NUM> will be omitted below.

Flying object <NUM> includes body <NUM> and a plurality of motor units <NUM>. Body <NUM> includes a plurality of main wings <NUM> and a plurality of empennages <NUM>. Similarly to body <NUM> of flying object <NUM>, body <NUM> also includes a flight controller and a power source.

Main wings <NUM> are each attached with motor unit <NUM>. When the flight direction of flying object <NUM> is defined as forward, each motor unit <NUM> is attached to main wing <NUM> such that first rotary vane <NUM> and second rotary vane <NUM> are positioned in front of stator <NUM>, and the propulsion force generated by each of first rotary vane <NUM> and second rotary vane <NUM> acts forward.

<FIG> illustrates still another flying object <NUM> including motor unit <NUM> of the present exemplary embodiment. Flying object <NUM> has elements common to flying object <NUM> illustrated in <FIG>. For this reason, the description of matters of flying object <NUM> overlapping with flying object <NUM> will be omitted below.

Flying object <NUM> includes body <NUM> and one motor unit <NUM>. Body <NUM> has the same configuration as that of body <NUM> of flying object <NUM> illustrated in <FIG>. Motor unit <NUM> is attached to a nose, which is a front end of body <NUM>. Motor unit <NUM> is attached to body <NUM> such that first rotary vane <NUM> and second rotary vane <NUM> are positioned in front of stator <NUM>, and the propulsion force generated by first rotary vane <NUM> and second rotary vane <NUM> acts in front.

In the above description, the gear has been described with, as an example, the configuration in which bevel gears <NUM>, <NUM>, <NUM> are used. The gear is not limited to the bevel gear as long as the same effects as those described above can be obtained. For example, the gear can have a similar configuration even when a spur gear is used.

As is obvious from the exemplary embodiment described above, motor unit (<NUM>) of a first aspect includes the following configuration. Motor unit (<NUM>) includes stator (<NUM>), rotor (<NUM>), and gear unit (<NUM>). Rotor (<NUM>) is positioned around stator (<NUM>) and rotates by a magnetic force generated in stator (<NUM>) to generate a rotational force of first rotary vane (<NUM>). Gear unit (<NUM>) has bevel gears (<NUM>, <NUM>, <NUM>), which are a plurality of gears. Gear unit (<NUM>) converts the rotational force generated by rotor (<NUM>) to generate a rotational force for rotating second rotary vane (<NUM>) in an inverse direction to the rotation direction of first rotary vane (<NUM>). At least a part of the plurality of bevel gears (<NUM>, <NUM>, <NUM>) are positioned inside stator (<NUM>).

According to this aspect, since at least a part of the plurality of bevel gears (<NUM>, <NUM>, <NUM>) are positioned inside stator (<NUM>), it is possible to suppress an increase in size in the direction in which axial center (<NUM>) of motor unit (<NUM>) extends. First rotary vane (<NUM>) and second rotary vane (<NUM>) can be disposed close to stator (<NUM>) and rotor (<NUM>) in the direction in which axial center (<NUM>) of rotor (<NUM>) extends. For this reason, by shortening the members such as shafts (<NUM>, <NUM>) that transmit the rotational force of rotor (<NUM>) to first rotary vane (<NUM>) and second rotary vane (<NUM>), it is possible to suppress vibration of the members such as shafts (<NUM>, <NUM>). This makes it possible to achieve weight reduction such as thinning of members such as shafts (<NUM>, <NUM>). When the members such as shafts (<NUM>, <NUM>) are made light as described above, the weight of entire flying object (<NUM>, <NUM>, <NUM>) can be reduced in a case where motor unit (<NUM>) of the present aspect is mounted on flying object (<NUM>, <NUM>, <NUM>), and the time or distance in which flying object (<NUM>, <NUM>, <NUM>) flies per unit can be extended.

Motor unit (<NUM>) of a second aspect can be achieved by a combination with the first aspect. In the second aspect, most of the plurality of bevel gears (<NUM>, <NUM>, <NUM>) are positioned inside stator (<NUM>). Specifically, more than half of the plurality of bevel gears (<NUM>, <NUM>, <NUM>) are positioned inside stator (<NUM>).

According to this aspect, it is possible to further suppress an increase in size in the direction in which axial center (<NUM>) of motor unit (<NUM>) extends.

Motor unit (<NUM>) of a third aspect can be achieved by a combination with the first or second aspect. Motor unit (<NUM>) of the third aspect further includes first shaft (<NUM>) and second shaft (<NUM>). First shaft (<NUM>) transmits the rotational force generated by rotor (<NUM>) to first rotary vane (<NUM>). Second shaft (<NUM>) transmits the rotational force generated by gear unit (<NUM>) to second rotary vane (<NUM>). First shaft (<NUM>) is formed in a tubular shape, is positioned around second shaft (<NUM>), and is rotatably supported by second shaft (<NUM>).

According to this aspect, it is possible to support first shaft (<NUM>) by using second shaft (<NUM>) that transmits, to second rotary vane (<NUM>), the rotational force output by gear unit (<NUM>). Therefore, it is possible to suppress an increase in size in a direction orthogonal to axial center (<NUM>) of motor unit (<NUM>).

Motor unit (<NUM>) of a fourth aspect can be achieved by a combination with any one of the first to third aspects. The plurality of bevel gears (<NUM>, <NUM>, <NUM>) of the fourth aspect include first bevel gear (<NUM>) connected to rotor (<NUM>).

According to this aspect, it is possible to further suppress an increase in size of motor unit (<NUM>).

Motor unit (<NUM>) of a fifth aspect can be achieved by a combination with any one of the first to third aspects. Gear unit (<NUM>) of the fifth aspect includes first bevel gear (<NUM>), second bevel gear (<NUM>), and third bevel gear (<NUM>) as a plurality of bevel gears. First bevel gear (<NUM>) rotates in the rotation direction of rotor (<NUM>) by the rotational force generated by rotor (<NUM>). Second bevel gear (<NUM>) meshes with first bevel gear (<NUM>). Third bevel gear (<NUM>) meshes with second bevel gear (<NUM>) and rotates in a direction opposite to first bevel gear (<NUM>) to generate a rotational force of second rotary vane (<NUM>).

According to this aspect, by using first bevel gear (<NUM>), second bevel gear (<NUM>), and third bevel gear (<NUM>), it is possible to convert the rotational force generated in rotor (<NUM>) into the rotational force in the opposite direction for rotating second rotary vane (<NUM>).

Motor unit (<NUM>) of a sixth aspect can be achieved by a combination with the first or second aspect. The sixth aspect has the following configuration. Motor unit (<NUM>) further includes first shaft (<NUM>) and second shaft (<NUM>). First shaft (<NUM>) transmits the rotational force generated by rotor (<NUM>) to first rotary vane (<NUM>). Second shaft (<NUM>) transmits the rotational force generated by gear unit (<NUM>) to second rotary vane (<NUM>). Gear unit (<NUM>) includes first bevel gear (<NUM>), second bevel gear (<NUM>), and third bevel gear (<NUM>) as the plurality of bevel gears. First bevel gear (<NUM>) rotates in the rotation direction of rotor (<NUM>) by the rotational force generated by rotor (<NUM>). Second bevel gear (<NUM>) meshes with first bevel gear (<NUM>). Third bevel gear (<NUM>) meshes with second bevel gear (<NUM>) and rotates in a direction opposite to first bevel gear (<NUM>) to generate a rotational force of second rotary vane (<NUM>). First shaft (<NUM>) rotates integrally with first bevel gear (<NUM>). Second shaft (<NUM>) rotates integrally with third bevel gear (<NUM>).

According to this aspect, by using first bevel gear (<NUM>), second bevel gear (<NUM>), and third bevel gear (<NUM>), it is possible to convert the rotational force generated in rotor (<NUM>) into the rotational force in the inverse direction for rotating second rotary vane (<NUM>). First rotary vane (<NUM>) can be rotated by first shaft (<NUM>) that rotates integrally with first bevel gear (<NUM>). Second rotary vane (<NUM>) can be rotated by second shaft (<NUM>) that rotates integrally with third bevel gear (<NUM>).

Motor unit (<NUM>) of a seventh aspect can be achieved by a combination with the fifth or sixth aspect. First bevel gear (<NUM>) of the seventh aspect is a bevel gear connected to rotor (<NUM>).

Motor unit (<NUM>) of an eighth aspect can be achieved by a combination with any one of the first to seventh aspects. Motor unit (<NUM>) of the eighth aspect further includes a lubricant, a cover member (first bevel gear <NUM>), accommodating part (<NUM>), and magnetic fluid (<NUM>). The lubricant lubricates the mesh part of the plurality of bevel gears (<NUM>, <NUM>, <NUM>). Cover member (<NUM>) rotates together with rotor (<NUM>). Accommodating part (<NUM>) is positioned inside stator (<NUM>), includes opening (<NUM>) covered by cover member (<NUM>), and accommodates the plurality of bevel gears (<NUM>, <NUM>, <NUM>) and the lubricant. Magnetic fluid (<NUM>) seals between accommodating part (<NUM>) and cover member (<NUM>).

According to this aspect, it is possible to cover opening (<NUM>) of accommodating part (<NUM>) using cover member (<NUM>) that rotates together with rotor (<NUM>), and it is possible to further suppress an increase in size of motor unit (<NUM>). By sealing between accommodating part (<NUM>) and cover member (<NUM>) with magnetic fluid (<NUM>), it is possible to suppress the lubricant in accommodating part (<NUM>) from coming out to the outside.

Motor unit (<NUM>) of a ninth aspect can be achieved by a combination with any one of the first to eighth aspects. Motor unit (<NUM>) of the ninth aspect further includes first rotary vane (<NUM>) and second rotary vane (<NUM>).

Flying object (<NUM>, <NUM>, <NUM>) of a tenth aspect has the following configuration. Flying object (<NUM>, <NUM>, <NUM>) includes a motor unit (<NUM>) and body (<NUM>, <NUM>, <NUM>). Motor unit (<NUM>) is motor unit (<NUM>) of the ninth aspect. Motor unit (<NUM>) is attached to body (<NUM>, <NUM>, <NUM>).

According to this aspect, it is possible to reduce the weight of members such as shafts (<NUM>, <NUM>) of motor unit (<NUM>). Therefore, it is possible to reduce the weight of entire flying object (<NUM>, <NUM>, <NUM>), and it is possible to extend the time or distance in which flying object (<NUM>, <NUM>, <NUM>) flies per unit.

Claim 1:
A motor unit (<NUM>) comprising
a stator (<NUM>);
a rotor (<NUM>) positioned around the stator and configured to be rotated by a magnetic force generated by the stator to generate a rotational force of a first rotary vane (<NUM>); and
a gear unit (<NUM>) that includes a plurality of gears (<NUM>, <NUM>, <NUM>) and configured to convert the rotational force generated by the rotor to rotate a second rotary vane (<NUM>) in an inverse direction to a rotation direction of the first rotary vane,
wherein at least some of the plurality of gears are positioned inside the stator.