ROTARY MACHINE

Abstract

A rotary machine capable of preventing leakage of a coolant and simply and efficiently cooling a rotor is provided. A motor 1 has a rotor 20 made by laminating magnetic steel sheets, a stator 30 arranged around the rotor 20, a rotary shaft 10 passed through a central part of the rotor 20, and an annular sleeve 27 arranged between the rotary shaft 10 and the rotor 20. On an outer circumferential face of the rotary shaft 10, a groove 12 serving as a coolant flow path for guiding a coolant is formed. The groove 12 may be formed only on the outer circumferential face of the rotary shaft 10, or only on an inner circumferential face of the sleeve 27, or on both the outer circumferential face of the rotary shaft 10 and the inner circumferential face of the sleeve 27.

Description

TECHNICAL FIELD

The present invention relates to a rotary machine employing a coolant to cool a motor.

BACKGROUND ART

Cooling a rotary machine used for an electric vehicle and the like with the use of a coolant is useful to efficiently generate driving force (torque) by use of electric power. As an example of such a cooling technique for a rotary machine, there is a technique of cooling a rotor incorporating permanent magnets with a coolant. Related arts are disclosed in Japanese Unexamined Patent Application Publications No. 2002-345188, No. 2010-220340, and No. 2010-252544 and Japanese Patent Publication No. 4469670.

CITATION LIST

Patent Literature

• Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2002-345188
• Patent Literature 2: Japanese Unexamined Patent Application Publication No. 2010-220340
• Patent Literature 3: Japanese Unexamined Patent Application Publication No. 2010-252544
• Patent Literature 4: Japanese Patent Publication No. 4469670

SUMMARY OF INVENTION

Problem to be Solved by Invention

In connection with using a coolant to cool a rotor incorporating permanent magnets of a rotary machine, the present inventors have studied the structural details of the rotary machine to further improve cooling efficiency. During the studying process, it has been found that further suppressing a mechanical loss of the rotary machine has a room for improvement in connection with a structure for cooling the rotor that incorporates permanent magnets with a coolant. The present invention has been made in consideration of this issue and an object of the present invention is to provide a rotary machine that converts electric power into torque, or torque into electric power at higher efficiency.

Means to Solve Problem

An aspect of the present invention provides a rotary machine including a rotor made by laminating magnetic steel sheets; a stator arranged around the rotor; a rotary body passed through a central part of the rotor; an annular sleeve member arranged between the rotary body and the rotor; and a recess formed on at least one of an outer circumferential face of the rotary body and an inner circumferential face of the sleeve member and serving as a coolant flow path to guide a coolant.

Effects of Invention

According to the rotary machine of the present invention, a mold member is formed at each end of a stator core, to cover a base part of a coil end part. A partition member is attached in contact with the mold member, to separate a first space accommodating the rotor from a second space accommodating the coil end part. Accordingly, there is provided an effect of realizing efficient cooling without increasing costs or deteriorating performance.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a sectional side view illustrating the structure of a motor, i.e., a rotary machine according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along a line A-A of FIG. 1 as seen from an arrowed direction.

FIG. 3 is a perspective view of a rotary shaft of the motor, i.e., the rotary machine according to the first embodiment of the present invention.

FIG. 4 is a view illustrating grooves formed on the rotary shaft of the motor, i.e., the rotary machine according to the first embodiment of the present invention.

FIG. 5 is a sectional side view illustrating the structure of a motor, i.e., a rotary machine according to a second embodiment of the present invention.

FIG. 6 is a sectional view taken along a line B-B of FIG. 5 as seen from an arrowed direction;

FIG. 7 is a sectional view illustrating a sectional shape of a groove formed on a sleeve of FIG. 1 or 5.

FIG. 8 is a sectional view illustrating a sectional shape of a groove formed on the rotary body and sleeve of FIG. 1 or 5.

FIG. 9 is a sectional side view illustrating the structure of a motor, i.e., a rotary machine according to a third embodiment of the present invention.

FIG. 10 is a sectional side view illustrating a stator extracted from the rotary machine according to the third embodiment of the present invention.

FIG. 11 is a sectional view taken along a line D-D of FIG. 10 as seen from an arrowed direction.

FIG. 12 is a sectional view taken along a line C-C of FIG. 9 as seen from an arrowed direction.

FIG. 13 is a view illustrating sealing methods for a partition member according to the third embodiment of the present invention.

FIG. 14 is a sectional side view illustrating the structure of a motor, i.e., a rotary machine according to a fourth embodiment of the present invention.

FIG. 15 is a sectional side view illustrating the structure of a motor, i.e., a rotary machine according to a fifth embodiment of the present invention.

MODE OF IMPLEMENTING INVENTION

Rotary machines according to embodiments of the present invention will be explained in detail with reference to the drawings. In the embodiments mentioned below, the rotary machines each are, as an example, a motor (an electric motor) driven and rotated with an externally supplied current (such as a three-phase AC current).

First Embodiment

FIG. 1 is a sectional side view illustrating the structure of a motor, i.e., a rotary machine according to the first embodiment of the present invention. FIG. 2 is a sectional view taken along a line A-A of FIG. 1 as seen from an arrowed direction.

As illustrated in FIG. 1, the motor 1 has a rotary shaft 10, a rotor (rotator) 20, a sleeve (sleeve member) 27, a stator (stationary element) 30, and a housing 40. An externally supplied current creates electromagnetic force between the rotor 20 and the stator 30, to rotate the rotor 20, thereby rotationally driving the rotary shaft 10. In the following explanation, a left-right direction of FIG. 1 in which the rotary shaft 10 extends is referred to as “axial direction”.

The rotary shaft 10 is a shaft member to transmit torque of the rotor 20 to the outside and includes a first shaft part (first rotary body part) 10a and a second shaft part (second rotary body part) 10b. The first shaft part 10a has a cylindrical shape and extends leftward in the axial direction from a central part of a left side face of the second shaft part 10b and rightward in the axial direction from a central part of a right side face of the second shaft part 10b. The second shaft part 10b has a cylindrical shape having a larger diameter than the first shaft part 10a.

In the rotary shaft 10, the second shaft part 10b is passed through a central part of the rotor 20, and together with the sleeve 27, is fixed to the rotor 20. A first side of the first shaft part 10a leftward protrudes from the housing 40 and a second side of the first shaft part 10a rightward protrudes from the housing 40. The first shaft part 10a is freely rotatably supported with bearings B1 and B2 arranged in the housing 40. Accordingly, the rotary shaft 10, rotor 20, and sleeve 27 integrally rotate around a rotation axis of the rotary shaft 10. The bearings B1 and B2 are, for example, antifriction bearings such as angular ball bearings.

Inside the first shaft part 10a of the rotary shaft 10, a coolant flow path (first flow path) 11 is formed along a center axis up to the inside of the second shaft part 10b. On an outer circumferential face of the second shaft part 10b of the rotary shaft 10, a groove (recess) 12 is formed as a coolant flow path to guide a coolant (such as cooling oil) to cool permanent magnets 23 arranged in the rotor 20. As illustrated in FIG. 2, this embodiment forms eight grooves 12 each having a rectangular sectional shape at regular intervals in a circumferential direction of the second shaft part 10b.

FIG. 3 is a perspective view of the rotary shaft of the motor 1, i.e., the rotary machine according to the embodiment. As illustrated in FIG. 3(a), the grooves 12 are linearly formed in the axial direction on the second shaft part 10b of the rotary shaft 10. The grooves 12 are formed not to reach each axial end of the second shaft part 10b but they are formed to extend from the vicinity of one axial end of the second shaft part 10b up to the vicinity of the other axial end thereof. This is to at most prevent the coolant supplied to the grooves 12 serving as coolant flow paths from leaking outside through a gap between the rotary shaft 10 (second shaft part 10b) and the sleeve 27.

The grooves 12 formed on the outer circumferential face of the rotary shaft 10 may be spiral in the axial direction as illustrated in FIG. 3(b), or may be winding in the axial direction as illustrated in FIG. 3(c). When the grooves 12 are spiral as illustrated in FIG. 3(b), a circumferential temperature distribution of the rotor 20 will be equalized compared with the linearly formed grooves illustrated in FIG. 3(a). When the grooves 12 are winding as illustrated in FIG. 3(c), the cooling efficiency of the rotor 20 will improve compared with the linearly formed grooves 12 illustrated in FIG. 3(a).

FIG. 4 is a view illustrating sectional shapes of grooves formed on the rotary shaft of the motor 1, i.e., the rotary machine according to the embodiment. As illustrated in FIG. 4(a), the embodiment forms the grooves each into a rectangular sectional shape on the outer circumferential face of the second shaft part 10b of the rotary shaft 10. The sectional shape of each groove 12 may be an arc shape (a convex arc oriented toward the rotation axis) as illustrated in FIG. 4(b), or a triangular shape (with one vertex oriented toward the rotation axis) as illustrated in FIG. 4(c).

Instead of arranging the plurality of thin and long axial grooves 12 in the circumferential direction of the second shaft part 10b as illustrated in FIGS. 4(a) to 4(c), the outer circumferential face of the second shaft part 10b may generally be recessed as illustrated in FIG. 4(d). Namely, the outer circumferential face of the second shaft part 10b except axial ends thereof may generally be hollowed to form a recess. Such a recess may be realized by forming, for example, a countless number of the linear grooves 12 of FIG. 4(a) in the circumferential direction.

Inside the second shaft part 10b of the rotary shaft 10, a communicating flow path (second flow path) 13 is formed to connect the coolant flow path 11 formed in the first shaft part 10a to each groove 12 formed on the outer circumferential face of the second shaft part 10b. As illustrated in FIG. 2, the communicating flow paths 13 are formed to extend from the coolant flow path 11 toward the grooves 12 in diametral directions of the second shaft part 10b (more precisely, in different eight directions).

As illustrated in FIG. 2, the rotary shaft 10 is positioned in a rotation direction of the rotor 20 so that the grooves 12 formed on the outer circumferential face of the second shaft part 10b come nearest to the permanent magnets 23 of the rotor 20, respectively. This is to increase the cooling efficiency of the rotor 20 by bringing the grooves 12 serving as the coolant flow paths for guiding the coolant closest to the permanent magnets 23 as heat generating sources.

The rotor 20 has a rotor core 21, end rings 22, and the permanent magnets 23, is attached together with the sleeve 27 to the rotary shaft 10, and is rotatable around the rotation axis of the rotary shaft 10. As illustrated in FIG. 1, the rotor core 21 is made by laminating magnetic steel sheets made of magnetic material with an adhesive and is an annular member with the rotary shaft 10 being passed through a central part of the rotor core 21.

The permanent magnet 23 is, for example, a rectangular parallelepiped magnet extending in the axial direction and is inserted into an insertion hole formed in the rotor core 21. The permanent magnets 23 are arranged at regular intervals along an outer circumferential face of the rotor core 21. According to the example illustrated in FIG. 2, eight permanent magnets 23 each having a rectangular sectional shape are arranged at regular intervals in a circumferential direction of the rotor core 21. Alternating magnetic fields along the outer circumferential face of the rotor core 21 is formed by way of this arrangements.

The end ring 22 is arranged at each axial side (in the laminated direction of the magnetic steel sheets) of the rotor core 21. The end rings 22 are annular members that axially hold the rotor core 21 from each side. An axial length of the rotor core 21 is set so that the length of the rotor core 21 including the end rings 22 arranged at each axial side of the rotor core 21 is equal to an axial length of the second shaft part 10b of the rotary shaft 10.

The sleeve 27 is an annular member arranged between the second shaft part 10b of the rotary shaft 10 and the rotor 20 and is made of, for example, the same material as the rotary shaft 10. An axial length of the sleeve 27 is set to be equal to an axial length of the second shaft part 10b of the rotary shaft 10. The sleeve 27 is fitted to the outer circumferential face of the second axial part 10b of the rotary shaft 10 by, for example, shrinkage fitting. When the sleeve 27 is fitted to the outer circumferential face of the second shaft part 10b of the rotary shaft 10, the grooves 12 form coolant flow paths between the rotary shaft 10 and the sleeve 27.

The coolant guided into the grooves 12 serving as the coolant flow paths flows between the rotary shaft 10 (the second shaft part 10b) and the sleeve 27. Even if the rotor 20 is rotated at a high speed under a condition that the bonding strength of the adhesive that adheres the magnetic steel sheets of the rotor core 21 together decreases due to a temperature increase of the motor 1, this configuration prevents the coolant guided into the grooves 12 serving as the coolant flow paths from leaking. The rotor core 21 mentioned above is fitted to the outer circumferential face of the sleeve 27 by, for example, shrinkage fitting.

Since the sleeve 27 is fitted to the outer circumferential face of the second shaft part 10b by, for example, shrinkage fitting, the coolant guided into the grooves 12 almost causes no leakage. There will be leakage if the pressure of the coolant guided into the grooves 12 is high. To deal with this, at each axial end, the sleeve 27 is soldered or welded to the second shaft part 10b of the rotary shaft 10, or a sealing material such as an O-ring is arranged between the sleeve 27 and the second shaft part 10b of the rotary shaft 10, to seal the location.

The stator 30 has a stator core 31 and a coil 32 and is fixed to an inner circumferential face of a body member 41 forming part of the housing 40, to surround the rotor 20 in the rotation direction of the rotary shaft 10. According to a current externally supplied to the coil 32, the stator 30 forms a rotating magnetic field in the circumferential direction of the rotor 20. Like the rotor core of the rotor 20, the stator core 31 is an annular member formed by laminating a plurality of magnetic steel sheets made of magnetic material. The rotor 20 is arranged on an inner circumferential side of the stator core 31. An inner diameter of the stator core 31 is so set to form an annular gap (an air gap G illustrated in FIG. 1) having preset dimensions between the inner circumferential face of the stator core 31 and the outer circumferential face of the rotor 20.

The coil 32 is inserted into a slot (not illustrated) formed in the stator core 31, to form magnetic poles according to an externally supplied current. The coil 32 includes a first coil to which a U-phase current of three-phase AC is supplied, a second coil to which a V-phase current is supplied, and a third coil to which a W-phase current is supplied. These first to third coils are sequentially arranged in the circumferential direction of the stator core 31. When a three-phase AC current is supplied to the coil 32, a rotating magnetic field is formed along the inner circumferential face of the stator core 31. As illustrated in FIG. 1, the coil 32 is attached to the stator core 31 so that a coil end part protrudes from each end of the stator core 31.

The housing 40 includes the body member 41, a left sidewall member 42, and a right sidewall member 43, accommodates part of the rotary shaft 10, the rotor 20, the sleeve 27, and the stator 30, and forms an external shape of the motor 1. The body member 41 is made of iron alloy and the like and is a cylindrical member with each axial end being open. To the inner circumferential face of the body member 41, the above-mentioned stator 27 is fixed. The left sidewall member 42 is a disk-shaped member, has a fitting hole for the bearing B1 at a central part thereof, and is attached to a left end of the body member 41. The right sidewall member 43 is a disk-shaped member, has a fitting hole for the bearing B2 at a central part thereof, and is attached to a right end of the body member 41.

Operation of the motor 1 with the above-mentioned structure will briefly be explained. When an external three-phase AC current is supplied to the motor 1, each phase current of the three-phase AC current passes through the coil 32 (first to third coils) arranged in the stator 30, to form a rotating magnetic field in the rotation direction of the rotor 20 according to the supplied current. The rotor core 21 with alternating magnetic fields formed along the outer circumference thereof interacts with the rotating magnetic field, to create attractive force and repulsive force. This results in rotating the rotor 20 to rotate the rotary shaft 10, rotor 20, and sleeve 27 together, thereby transmitting torque of the rotary shaft 10 to the outside.

When the motor 1 is driven, a pump (not illustrated) supplies a coolant to the coolant flow path 11 at a first side of the first shaft part 10a of the rotary shaft 10. The coolant supplied to the coolant flow path 11 is guided through the communicating flow paths 13 at a first end side (left side) of the second shaft part 10b to the grooves 12 formed on the outer circumferential face of the second shaft part 10b. Between the rotary shaft 10 and the sleeve 27, the grooves 12 form coolant flow paths. Accordingly, the coolant guided into the grooves 12 cools the permanent magnets 23. These coolant flow paths are formed to be nearest to the permanent magnets 23 arranged in the rotor 20, and therefore, the rotor core 21 and permanent magnets 23 are efficiently cooled. The coolant passed through the grooves 12 serving as the coolant flow paths is guided through the communicating flow paths 13 at a second end side (right side) of the second shaft part 10b to the coolant flow path 11 at a second side of the first shaft part 10a and is discharged outside.

As mentioned above, this embodiment forms the grooves serving as coolant flow paths on the outer circumferential face of the rotary shaft 10 and arranges the annular sleeve 27 between the rotary shaft 10 on which the grooves 12 are formed and the rotor 20, so that a coolant guided into the grooves 12 passes between the rotary shaft 10 and the sleeve 27. Even if the rotor 20 is rotated at a high speed under a condition that the bonding strength of the adhesive fixing the magnetic steel sheets of the rotor core 21 together decreases due to a temperature increase of the motor 1, the embodiment prevents the coolant guided into the grooves 12 from leaking.

This embodiment forms the grooves 12 on the outer circumferential face of the second shaft part 10b of the rotary shaft 10 that is larger in diameter than the first shaft part 10a and arranges the sleeve 27 between the second shaft part 10b on which the grooves 12 are formed and the rotor 20, thereby positioning the coolant flow paths closest to the permanent magnets 23. Accordingly, the rotor 20 including the permanent magnets 23 is simply and efficiently cooled.

The number, length, and shape (including sectional shape) of the grooves 12 formed on the rotary shaft 10 are not limited to those of the above-mentioned embodiment.

The rotation-direction (circumferential-direction) arrangements and positional relationships of the grooves 12 formed on the rotary shaft 10 and the permanent magnets 23 arranged in the rotor 20 are not limited to those of the above-mentioned embodiment. These arrangements and positional relationships are optional.

Although the above-mentioned embodiment has explained, as an example, the rotary shaft 10 that has the first shaft part 10a and second shaft part 10b that are integrated into one body, the present invention is applicable to a rotary shaft made of a first shaft part 10a and second shaft part 10b that are discrete members. For example, the rotary shaft 10 may be made of a cylindrical shaft member whose outer diameter is similar to that of the first shaft part 10a and a cylindrical auxiliary member that has an outer diameter similar to that of the second shaft part 10b and an inner diameter similar to that of the first shaft part 10a and is fixed to the cylindrical shaft member.

Second Embodiment

FIG. 5 is a sectional side view illustrating the structure of a motor, i.e., a rotary machine according to the second embodiment of the present invention. The motor 1 of the first embodiment illustrated in FIGS. 1 to 4 is of an inner ring rotating type that turns the rotor 20 together with the rotary shaft 10. On the other hand, the motor 2 of the second embodiment illustrated in FIG. 5 is of an outer ring rotating type that turns a rotor 20 around a fixed center shaft 70.

The motor 2 of this embodiment attaches outer housings 61 and 62 to left and right outer sides of a housing 40 as illustrated in FIG. 5. Fitting holes 61c and 62c of the outer housings 61 and 62 fixedly support ends of the center shaft 70. With bearings B1 and B2, the center shaft 70 rotatably supports a cylindrical rotary body 80 (second rotary body part) that forms part of the rotor 20. On an outer circumferential face of the rotary body 80, a sleeve 27 is attached, and on an outer circumferential face of the sleeve 27, the rotor 20 is attached.

Inside the center shaft 70, a rotor oil introducing flow path 71 is formed to open at each end of the center shaft 70. To the rotor oil introducing flow path 71, an oil supply unit such as an oil pump (not illustrated) supplies oil for cooling the rotor 20.

To end faces of the rotary body 80, rotary support members 25 and 26 (first rotary body part) are attached with their center axes being positionally aligned to each other. The rotary support members 25 and 26 are inserted into openings 42c and 43c formed at centers of left sidewall member 42 and right sidewall member 43 of the housing 40 with proper gaps interposed between them, are axially outwardly protruded from the left and right sidewall members 42 and 43, respectively, and are rotatably supported by the center shaft 70 through the bearings B1 and B2. The rotary support members 25 and 26 form part of the rotor 20.

The rotary support members 25 and 26 have paths to connect an oil flow path 24 and inner spaces of the bearings B1 and B2 to each other. These paths guide oil from the oil flow path 24 through the inner spaces of the bearings B1 and B2 to the open sides of the rotary support members 25 and 26.

The rotary support members 25 and 26 form, with respect to the center shaft 70, annular gaps 25a and 26a (first flow path) for guiding oil in the axial direction of the center shaft 70. The rotary body 80 has a larger diameter than the rotary support members 25 and 26.

Between an inner circumferential face of the rotary body 80 and an outer circumferential face of the center shaft 70, an annular gap 28 is formed. The gap 28 communicates with the rotor oil introducing flow path 71 opened to the outer circumferential face of the center shaft 70 and the oil flow path 24 of the rotary body 80.

The oil flow path 24 includes a gap flow path 35 extending along the outer circumferential face of the rotary body 80 in the axial direction of the rotary body 80 and an inlet flow path 37 and an outlet flow path 39 that extend in a diametral direction of the rotary body 80 and connect both ends of the gap flow path 35 to the gap 28.

A plurality of the oil flow paths 24 are arranged in a circumferential direction for permanent magnets 23, respectively. Namely, as illustrated in FIG. 6, the oil flow paths 24 are formed in the vicinities of the permanent magnets 23 on the outer circumferential face of the rotary body 80. The oil flow paths 24 formed in the circumferential direction of the rotary body 80 alternate the flowing directions of oil passing therethrough.

On the outer circumferential face of the rotary body 80, grooves (recesses) 12 are formed to form the gap flow paths 35 with respect to the inner circumferential face of the sleeve 27. According to this embodiment, eight grooves 12 each having a rectangular sectional shape are formed at regular intervals in the circumferential direction of the rotary body 80 as illustrated in FIG. 6.

As illustrated in FIG. 6, the rotary body 80 is positioned in a rotation direction of a rotor core 21 so that the grooves 12 formed on the outer circumferential face of the rotary body 80 come closest to the permanent magnets 23 of the rotor core 21, respectively. This is to improve the cooling efficiency of the rotor 20 by way of bringing the grooves 12 forming the gap flow paths 35 of the oil flow paths 24 for guiding oil as close to the permanent magnets 23, i.e., heat generating sources as possible.

The rotor 20 has the rotor core 21, the permanent magnets 23, and end rings 22, is attached together with the sleeve 27 to the rotary body 80, and is rotatable with the rotary body 80 around the center shaft 70. As illustrated in FIG. 5, the rotor core 21 is made by laminating magnetic steel sheets made of magnetic material with an adhesive and is an annular member with the rotary body 80 and sleeve 27 being passed through a central part of the rotor core 21.

The end ring 22 is arranged at each axial side (in the laminated direction of the magnetic steel sheets) of the rotor core 21. The end rings 22 are annular members that axially hold the rotor core 21 from each side. An axial length of the rotor core 21 is set so that the length of the rotor core 21 including the end rings 22 arranged at each axial side of the rotor core 21 is equal to an axial length of the rotary body 80.

The sleeve 27 is an annular member arranged between the rotary body 80 and the rotor 20 and is made of, for example, the same material as the center shaft 70 and rotary body 80. An axial length of the sleeve 27 is set to be equal to an axial length of the rotary body 80 and is fitted to the outer circumferential face of the rotary body 80 by, for example, shrinkage fitting. When the sleeve 27 is fitted to the outer circumferential face of the rotary body 80, the grooves 12 form the gap flow paths 35 between the rotary body 80 and the sleeve 27.

The oil guided into the grooves 12 forming part of the oil flow paths 24 flows between the rotary body 80 and the sleeve 27. Even if the rotor 20 is rotated at a high speed under a condition that the bonding strength of the adhesive that adheres the magnetic steel sheets of the rotor core 21 together decreases due to a temperature increase of the motor 2, this configuration prevents the oil guided into the grooves 12 forming part of the oil flow paths 24 from leaking. The rotor core 21 mentioned above is fitted to the outer circumferential face of the sleeve 27 by, for example, shrinkage fitting.

Since the sleeve 27 is fitted to the outer circumferential face of the rotary body 80 by, for example, shrinkage fitting, the oil guided into the grooves 12 almost causes no leakage. There will be leakage if the pressure of the oil guided into the grooves 12 is high. To deal with this, at each axial end, the sleeve 27 is soldered or welded to the rotary body 80, or a sealing material such as an O-ring is arranged between the sleeve 27 and the rotary body 80, to seal the location.

Operation of the motor 2 with the above-mentioned structure will briefly be explained. When the motor 2 is driven, a pump (not illustrated) supplies oil from an end opening of the center shaft 70 into the oil introducing flow path 71. The introduced oil flows from the oil introducing flow path 71 to the gap 28 on the outer circumferential side of the center shaft 70, passes the gap 28 in an axial outward direction, and flows into the oil flow paths 24.

The oil flowed into the oil flow paths 24 is guided into the grooves 12 formed on the outer circumferential face of the rotary body 80. Between the rotary body 80 and the sleeve 27, the grooves 12 form the gap flow paths 35, and therefore, the oil guided into the grooves 12 cools the permanent magnets 23. The grooves 12 are arranged to be closest to the permanent magnets 23 incorporated in the rotor core 21, and therefore, the rotor core 21 and permanent magnets 23 are efficiently cooled.

The oil passing through the gap flow paths 34 formed by the grooves 12 passes through the oil flow paths 24 and the internal spaces of the bearings B1 and B2 and reaches the openings of the rotary support members 25 and 26. Thereafter, the oil passes through the gaps 25a and 26a between the rotary support members 25 and 26 and the center shaft 70 and is discharged into spaces between the left sidewall member 42 and right sidewall member 43 of the housing 40 and the left sidewall member 61b and right sidewall member 62b of the outer housings 61 and 62.

As mentioned above, this embodiment forms the grooves 12 on the outer circumferential face of the rotary body 80 of the rotor 20 to form the gap flow paths 35 of the oil flow paths 24, and between the rotary body 80 on which the grooves 12 are formed and the rotor core 21, arranges the annular sleeve 27, so that the oil introduced into the grooves 12 may pass between the rotary body 80 and the sleeve 27. Even if the rotor 20 is rotated at a high speed under a condition that the bonding strength of the adhesive that adheres the magnetic steel sheets of the rotor core 21 together decreases due to a temperature increase of the motor 2, this configuration prevents the coolant guided into the grooves 12 from leaking.

This embodiment forms the grooves 12 on the outer circumferential face of the rotary body 80 that is larger in diameter than the rotary support members 25 and 26 and arranges the sleeve 27 between the rotary body 80 on which the grooves 12 are formed and the rotor core 21, thereby positioning the gap flow paths 35 closest to the permanent magnets 23. Accordingly, the rotor 20 incorporating the permanent magnets 23 is simply and efficiently cooled.

The number, length, and shape (including sectional shape) of the grooves 12 formed on the rotary body 80 are not limited to those mentioned above. The rotation-direction (circumferential-direction) arrangements and positional relationships of the grooves 12 formed on the outer circumferential face of the rotary body 80 and the permanent magnets 23 arranged in the rotor core 21 are not limited to those mentioned above. These arrangements and positional relationships are optional.

Although the above-mentioned embodiment integrates the rotary support members 25 and 26 and the rotary body 80 into one body, the rotary support members 25 and 26 and the rotary body 80 may be discrete members.

According to the first embodiment of FIGS. 1 to 4, the grooves 12 that are recesses to form coolant flow paths are formed on the outer circumferential face of the rotary shaft 10. According to the second embodiment of FIGS. 5 and 6, the grooves 12 that are recesses to form the gap flow paths 35 of the oil flow paths 24 are formed on the outer circumferential face of the rotary body 80. The grooves 12 may be formed on the inner circumferential face of the sleeve 27 as illustrated in FIG. 7, or may be formed on the outer circumferential face of the rotary shaft 10 (rotary body 80) and the inner circumferential face of the sleeve 27.

Third Embodiment

A motor 3 according to the third embodiment illustrated in FIGS. 9 to 13 uses oil as a coolant to cool a stator 30, which is the same as the stator of the motor 1 of the first embodiment. In FIG. 9, the internal structures of a rotary shaft 10 and rotor 20 are omitted. The details of the structure of the motor 3 according to the third embodiment will be explained.

The stator 30 has a stator core 31 and a coil 32 and is fixed to an inner circumferential face of a body member 41 forming part of a housing 40, to surround the rotor 20 in a rotation direction of the rotary shaft 10. According to a current externally supplied to the coil 32, the stator forms a rotating magnetic field in a circumferential direction of the rotor 20. FIG. 10 is a sectional side view illustrating the stator 30 extracted from the motor 3. FIG. 11 is a sectional view taken along a line D-D of FIG. 10 and seen from an arrowed direction.

As illustrated in FIG. 11, the stator core 31 has an annular yoke 31a and teeth 31b that are arranged in a circumferential direction of the yoke 31a and protrude toward a center axis of the yoke 31a. A clearance between the adjacent teeth 31b is a slot 31c into which the coil 32 is inserted. To avoid complication, FIG. 11 illustrates the stator core 31 having eight teeth 31b and eight slots 31c. These numbers may optionally be set.

The teeth 31b of the stator core 31 function as magnetic poles when three-phase AC is supplied to the coils 32 in the slots 31c. The stator core 31 is arranged around the rotor 20 so that the teeth 31b protrude toward a rotation axis of the rotary shaft 10. In this arrangement, a protrusion amount of the teeth 31b is set so that a gap between the teeth 31b and the rotor core forms an air gap G.

The coils 32 are inserted in the slots 31c formed in the stator core 31. The coils 32 are attached to the stator core 31 so that coil end parts 32a protrude from each end of the stator core 31. Namely, as illustrated in FIG. 10, the coil end parts 32a leftward protrude from a left end E1 of the stator core 31 and the coil end parts 32a protrude from a right end E2 of the stator core 31. Every coil 32 is attached to the stator core 31 as mentioned above, and therefore, the coil end parts 32a are circularly arranged along the ends E1 and E2 of the stator core 31 as illustrated in FIG. 10.

The ends E1 and E2 of the stator core 31 are provided with annular mold members 33a and 33b that extend along the ends E1 and E2 to cover base parts of the coil end parts 32a. The reason why the mold members 33a and 33b cover only the base parts of the coil end parts 32a instead of entirely covering the coil end parts 32a is to realize cooling with cooling oil OL and prevent the cooling oil from entering the air gap G between the rotor 20 and the stator 30.

Namely, covering only the base parts of the coil end parts 32a with the mold members 33a and 33b and exposing the remaining parts thereof realize that the cooling oil OL is directly poured onto the exposed parts of the coil end parts 32a, to efficiently cool the stator 30 (coils 32). As will be explained later in detail, front ends of partition parts 42b and 43b that are part of left sidewall member 42 and right sidewall member 43 of the housing 40 are sealed with the mold members 33a and 33b, to separate a space S1 (first space) accommodating the rotor 20 from a space S2 (second space) accommodating the coil end parts 32a, thereby preventing the oil from entering the air gap G.

The thickness of the mold members 33a and 33b is determined in consideration of a sealing degree and cooling efficiency. If the front ends of the partition parts 42b and 43b are not sealed, the oil will enter the air gap G. Accordingly, the thickness of the mold members 33a and 33b must be sufficient at least to seal the front ends of the partition parts 42b and 43b. As the thickness of the mold members 33a and 33b increases, the exposed part of the coil end parts 32a reduces to lower the cooling efficiency with oil. Accordingly, the thickness of the mold members 33a and 33b must be smaller than a thickness capable of securing a necessary cooling efficiency. The thickness of the mold members 33a and 33b is, for example, about 50% of the protruding amount of the coil end part 32a, preferably, about 20 to 30% of the protruding amount of the coil end part 32a.

As illustrated in FIG. 11, the inside of the stator core 31 is provided with a mold member 33c, which is similar to the mold members 33a and 33b, to bury an inner gap of each slot 31c formed in the stator core 31. The mold member 33c is arranged to fix the coil 32 inserted in the slot 31c so as to prevent the coil 32 from vibrating in the slot 31c and improve the cooling efficiency of the coil 32.

When a current is applied, the coil 32 becomes a heat generating source, and therefore, the mold members 33a and 33b covering the base parts of the coil end parts 32a and the mold member 33c fixing each coil 32 in each slot 31c are required to have a high thermal conductivity. It is preferable to form the mold members 33a, 33b, and 33c with thermally conductive resin mixed with thermally conductive fillers having an insulating characteristic, such as silicon oxide (SiO2) and aluminum oxide (Al2O3).

The mold members 33a and 33b and the mold member 33c may be made of material having the same thermal conductivity, or materials having different thermal conductivities. Each coil 32 attached to the stator core 31 has a higher wire concentration (wires that form the coil 32) at part inserted in the slot 31c and a front end of the coil end part 32a and a lower wire concentration at the base of the coil end part 32a. Heat resistance is higher at the part where the wire concentration is low (the base of the coil end part 32a) than at the part where the wire concentration is high (the inside of the slot 31c and the front end of the coil end part 32a). Accordingly, it is preferable to form the mold members 33a and 33b with a material whose thermal conductivity is higher than that of a material used to form the mold member 33c.

In connection with the mold resin 33a and 33b formed at the ends E1 and E2 of the stator core 31, a viscosity when forming them may be given priority to a thermal conductivity after forming them. In this case, the mold resin 33a and 33b may be formed with a material that has a lower thermal conductivity and viscosity than those of a material used to form the mold member 33c. Such a material is required when the material for the mold member 33c is insufficient to fill gaps at the base part of the coil end part 32a (gaps among the wires that form the coil 32).

In consideration of a functional difference between the mold members 33a and 33b and the mold member 33c, the mold members 33a and 33b and the mold member 33c may be formed from different materials. The mold members 33a and 33b are used to seal the front ends of the partition parts 42b and 43b, and therefore, they may be formed with a material having resiliency after the material hardens. On the other hand, the mold member 33c must surely fix the coil 32 in the slot 31c, and therefore, it may be formed from a material that increases hardness after the material hardens.

As illustrated in FIG. 9, vertically above the body member 41 of the housing 40, an oil supply port P1 (coolant supply port) is arranged to guide externally supplied cooling oil OL to the coil end parts 32a arranged inside the housing 40. The oil supply port P1 is arranged at a plurality of locations in the rotation direction of the rotary shaft 10 above an exposed part (a part not covered with the mold member 33a) of each coil end part 32a leftward protruding from the end E1 of the stator core 31 and above an exposed part (a part not covered with the mold member 33b) of each coil end part 32a rightward protruding from the end E2 of the stator core 31.

FIG. 12 is a sectional view taken along a line C-C of FIG. 9 and seen in an arrowed direction. As illustrated in FIG. 12, the oil supply ports P1 are arranged above the exposed parts of the coil end parts 32a at three locations in the rotation direction of the rotary shaft 10. The oil supply ports P1 are arranged at intervals of, for example, 20 to 70° in the rotation direction of the rotary shaft 10. Oil supplied from the oil supply ports P1 drops on different parts of the coil end parts 32a and flows downward along the exposed parts of the coil end parts 32a as indicated with arrows in FIG. 12. The bottom of the body member 41 is an oil pool OP where the oil downwardly moved along the exposed parts of the coil end parts 32a is temporarily kept.

Compared with dropping the oil OL only from one oil supply port P1, arranging the oil supply ports P1 at three locations in the rotation direction of the rotary shaft 10 and dropping the oil OL from these oil supply ports P1 are able to spread the oil OL over the whole of the exposed parts of the coil end parts 32a, thereby improving cooling efficiency. Although the example illustrated in FIG. 12 forms the oil supply ports P1 at three locations in the rotation direction of the rotary shaft 10, the oil supply ports P1 may be formed at two locations or more than four locations in the rotation direction of the rotary shaft 10 according to the size of the motor and the like. It is not always necessary to linearly arrange the oil supply ports P1 in the rotation direction of the rotary shaft 10. They may be axially shifted from one another.

As illustrated in FIG. 9, the left sidewall member 42 has a disk-shaped bottom plate part 42a and the cylindrical partition part (partition member) 42b. In the left sidewall member 42, the bottom plate part 42a is attached to a left end of the body member 41 so that the partition part 42b is arranged inside the body member 41. The bottom plate part 42a that forms part of the left sidewall member 42 has, at a central part thereof, a hole to fit the bearing B1. At an outer peripheral part of the bottom plate part 42a, an oil discharge port P2 is arranged to discharge the oil OL from the oil pool OP to the outside.

The partition part 42b that forms part of the left sidewall member 42 has an outer diameter substantially equal to an inner diameter of the stator core 31 (the mold member 33a). A front end of the partition part 42b is in contact with the mold member 33a, to separate the space S1 in which the rotor 20 is arranged from the space S2 in which the coil end parts 32a are arranged on the left side of the stator core 31. Namely, the front end of the partition part 42b is sealed with the mold member 33a, to separate the spaces S1 and S2 from each other.

Similar to the left sidewall member 42, the right sidewall member 43 has a disk-shaped bottom plate part 43a and the cylindrical partition part (partition member) 43b. In the right sidewall member 43, the bottom plate part 43a is attached to a right end of the body member 41 so that the partition part 43b is arranged inside the body member 41. The bottom plate part 43a that forms part of the right sidewall member 43 has, at a central part thereof, a hole to fit the bearing B2. At an outer peripheral part of the bottom plate part 43a, an oil discharge port P2 is arranged to discharge the oil OL from the oil pool OP to the outside.

The partition part 43b that forms part of the right sidewall member 43 has an outer diameter substantially equal to the inner diameter of the stator core 31 (the mold member 33b). A front end of the partition part 43b is in contact with the mold member 33b, to separate the space S1 in which the rotor 20 is arranged from the space S2 in which the coil end parts 32a are arranged on the right side of the stator core 31. Namely, the front end of the partition part 43b is sealed with the mold member 33b, to separate the spaces S1 and S2 from each other.

FIG. 13 is a view illustrating sealing methods for the partition member according to the embodiment. As mentioned above, the partition parts 42b and 43b of the left sidewall member 42 and right sidewall member 43 are sealed with their front ends being in contact with the mold members 33a and 33b. There will be various methods (sealing methods) of bringing the front ends of the partition parts 42b and 43b in contact with the mold members 33a and 33b, as illustrated in FIG. 13. Methods of sealing the partition part 42b with the mold member 33a will be explained. These method are also applicable to seal the partition part 43b with the mold member 33b.

The sealing method illustrated in FIG. 13(a) tapers an outer circumferential face of the front end of the partition part 42b and an inner circumferential face of the mold member 33a and wholly fits the front end of the partition part 42b to the inner circumferential face of the mold member 33a, thereby increasing a contact area between the partition part 42b and the mold member 33a. The sealing method illustrated in FIG. 13(b) tapers the outer circumferential face of the front end of the partition part 42b and forms steps in the inner circumferential face of the mold member 33a and wholly fits the front end of the partition part 42b to the inner circumferential face of the mold member 33a, thereby increasing contact locations between the partition part 42b and the mold member 33a.

The sealing method illustrated in FIG. 13(c) forms a flange F at the front end of the partition part 42b and a groove M on the inner circumferential face of the mold member 33a and fits the whole of the flange F formed at the front end of the partition part 42b to the groove M formed in the inner circumferential face of the mold member 33a, thereby improving a sealing degree between the partition part 42b and the mold member 33a. The sealing method illustrated in FIG. 13(d) forms a groove at the front end of the partition part 42b, arranges an O-ring R in the groove, and brings the whole of the O-ring R arranged at the front end of the partition part 42b in contact with the inner circumferential face of the mold member 33a, thereby improving a sealing degree between the partition part 42b and the mold member 33a.

The sealing method illustrated in FIG. 13(e) forms a protrusion Q entirely along the outer circumferential face of the front end of the partition part 42b and wholly brings the protrusion Q in contact with the inner circumferential face of the mold member 33a, thereby improving a sealing degree between the partition part 42b and the mold member 33a. The sealing method illustrated in FIG. 13(f) forms a notch K in the inner circumferential face of the mold member 33a and wholly fits the front end of the partition part 42b to the notch K formed in the mold member 33a, thereby improving a sealing degree between the partition part 42b and the mold member 33a.

Operation of the motor 3 with the above-mentioned configuration will briefly be explained. When the motor 3 is driven, a pump or the like (not illustrated) supplies cooling oil OL to the oil supply ports P1 and the oil drops onto a plurality of locations of the exposed parts of the coil end parts 32a arranged in the space S2. The oil OL dropped on the coil end parts 32a downwardly moves along the exposed parts of the coil end parts 32a as indicated with arrows in FIG. 12. Since the oil OL drops onto the plurality of locations of the coil end parts 32a, the oil OL wholly spreads over the coil end parts 32a arranged along the ends of the stator core 31, thereby efficiently cooling the coil end parts 32a.

The partition part 42b of the left sidewall member 42 is sealed with the mold member 33a and the partition part 43b of the right sidewall member 43 is sealed with the mold member 33b, so that, on both the left and right sides of the stator core 31, the space S1 in which the rotor 20 is arranged is separated from the space S2 in which the coil end parts 32a are arranged. This prevents the oil OL supplied from the oil supply ports P1 into the space S2 from entering the air gap G.

As mentioned above, this embodiment forms the mold members 33a and 33b at both ends of the stator core 31, to cover the base parts of the coil end parts 32a and arranges the partition parts 42b and 43b in contact with the mold members 33a and 33b, respectively, to separate the space S1 in which the rotor 20 is arranged from the space S2 in which the coil end parts 32a are arranged. This realizes efficient cooling without increasing costs or deteriorating performance.

Fourth Embodiment

FIG. 14 is a sectional side view illustrating the structure of a motor 4, i.e., a rotary machine according to the fourth embodiment of the present invention. The motor 4 of this embodiment illustrated in FIG. 14 differs from the motor 3 illustrated in FIG. 9 in that it attaches a resolver 50 to a rotary shaft 10, arranges a mold member 51 instead of the mold member 33a, and employs left sidewall member 52 and right sidewall member 53 instead of the left sidewall member 42 and right sidewall member 43.

The resolver 50 is a sensor to detect a rotation angle of the rotary shaft 10, and in the example illustrated in FIG. 14, is arranged on a right side of a bearing B2. The mold member 51 is formed to have an asymmetric shape with respect to a mold member 33b formed on a right side of a stator core 31 in connection with the axial direction of the rotary shaft 10. More precisely, the mold member 51 has an annular part 51a formed in an annular shape along an end (end E1) of the stator core 31 to cover base parts of coil end parts 32a and a cylindrical protrusion 51b leftward protruding from the annular part 51a. The annular part 51a has the same shape as the mold member 33a illustrated in FIG. 9.

Similar to the left sidewall member 42 illustrated in FIG. 9, the left sidewall member 52 is a member having a disk-shaped bottom plate part 52a and a cylindrical partition part (partition member) 52b. The partition part 52b of the left sidewall member 52 is shorter in the axial direction than the partition part 42b of the left sidewall member 42. This is because the above-mentioned mold member 51 has the cylindrical protrusion 51b leftward protruding from the annular part 51a, and therefore, the partition part 52b is able to be in contact with the mold member 51 without extended up to the annular part 51a of the mold member 51.

The right sidewall member 53 has a disk-shaped bottom plate part 53a, a cylindrical support part 53b, and a cylindrical partition part (partition member) 53c. The support part 53b supports, with its inner circumferential face, part of the bearing B2 and resolver 50. The partition part 53c is similar to the partition part 43b illustrated in FIG. 9 but is shorter in the axial direction than the partition part 43b by the portion of the support part 53b. In this way, the motor 4 of this embodiment has the resolver 50, and for this, the mold members 33b and 51 have asymmetrical shapes and the left sidewall member 52 and right sidewall member 53 have asymmetrical shapes.

According to this embodiment, the mold member 51 and mold member 33b are formed at ends of the stator core 31 to cover the base parts of the coil end parts 32a. The partition parts 52b and 53c are in contact with the mold members 51 and 33b, to separate a space S1 in which a rotor 20 is arranged from a space S2 in which the coil end parts 32a are arranged. Like the first embodiment, this embodiment is capable of carrying out efficient cooling without increasing costs or deteriorating performance.

Fifth Embodiment

A motor 5 according to the fifth embodiment illustrated in FIG. 15 employs oil as a coolant to cool the stator 30 of the motor 2 of the second embodiment. In FIG. 15, the internal structures of a rotary shaft 10 and rotor 20 are omitted. The structure of the motor 5 according to the fifth embodiment will be explained in detail.

In the motor 5 of this embodiment, a first end of a center shaft 70 is fixedly supported with an outer housing 61 that is on the left side of FIG. 15. The outer housing 61 has a body member 61a fixed to a left sidewall member 42 of a housing 40 and a left sidewall member 61b that closes a side of the body member 61a opposite to the housing 40. At the center of the left sidewall member 61b, a fitting hole 61c is formed to fix an outwardly protruding first end of the center shaft 70.

Similarly, a second end of the center shaft 70 is fixedly supported with an outer housing 62 that is on the right side of FIG. 15. The outer housing 62 has a body member 62a fixed to a right sidewall member 43 of the housing 40 and a right sidewall member 62b that closes a side of the body member 62a opposite to the housing 40. At the center of the right sidewall member 62b, a fitting hole 62c is formed to fix an outwardly protruding second end of the center shaft 70.

According to this embodiment, the motor 5 is of an outer ring rotating type with the rotor 20 rotating around the center shaft 70. Mold members 33a and 33b are formed at both ends of a stator core 31 to cover base parts of coil end parts 32a. Partition parts 42b and 43b are in contact with the mold members 33a and 33b, respectively, to separate a space S1 in which the rotor 20 is arranged from a space S2 in which the coil end parts 32a are arranged. Similar to the fourth embodiment, this embodiment is capable of carrying out efficient cooling without increasing costs or deteriorating performance.

INDUSTRIAL APPLICABILITY

The present invention is applicable not only to motors of electric vehicles but also generally and widely to rotary machines that convert electric power into torque, or rotary machines such as generators that convert torque into electric power.

EXPLANATION OF REFERENCE NUMERALS

• • 1, 2, 3, 4, 5: Motor
  • 10: Rotary shaft (Rotor shaft)
  • 10a: First shaft part (First rotary body part)
  • 10b: Second shaft part (Second rotary body part)
  • 11: Coolant flow path
  • 12: Groove
  • 13: Communicating flow path
  • 20: Rotor
  • 21: Rotor core
  • 23: Permanent magnet
  • 24: Oil flow path (Coolant flow path, Second flow path)
  • 25, 26: Rotary support member (First rotary body part)
  • 25a, 26a: Gap (First flow path)
  • 27: Sleeve (Sleeve member)
  • 30: Stator
  • 31: Stator core
  • 32: Coil
  • 32a: Coil end part
  • 33a, 33b: Mold member
  • 33c: Mold member
  • 42b, 43b: Partition part (Partition member)
  • 51: Mold member
  • 51a: Annular part
  • 51b: Protrusion
  • 52b, 53c: Partition part (Partition member)
  • 70: Center shaft (Rotor shaft)
  • 80: Rotary body (Second rotary body part)
  • P1: Oil supply port (Coolant supply port)
  • S1: First space
  • S2: Second space

Claims

1. A rotary machine comprising:

a rotor made by laminating magnetic steel sheets;

a stator arranged around the rotor;

a rotary body passed through a central part of the rotor;

an annular sleeve member arranged between the rotary body and the rotor; and

a recess formed on at least one of an outer circumferential face of the rotary body and an inner circumferential face of the sleeve member and serving as a coolant flow path to guide a coolant.

2. The rotary machine as set forth in claim 1, wherein

the rotary body includes a first rotary body part having a first flow path to guide the coolant in an axial direction of the rotary body and a second rotary body part that has a larger diameter than the first rotary body part and incorporates a second flow path to connect the first flow path and the coolant flow path to each other.

3. The rotary machine as set forth in claim 2, wherein

the recess is formed on an outer circumferential face of the second rotary body part.

4. The rotary machine as set forth in claim 1, wherein

the recess is a groove having a linear, spiral, or winding shape formed in the axial direction of the rotary body.

5. The rotary machine as set forth in claim 4, wherein the recess has a rectangular, arc, or triangular sectional shape.

6. The rotary machine as set forth in claim 1, wherein

the recess is formed in the same number as the number of permanent magnets arranged in the rotor.

7. The rotary machine as set forth in claim 6, wherein

the rotary body and sleeve member are positioned in a rotation direction of the rotor so that the recesses come closest to the permanent magnets, respectively.

8. The rotary machine as set forth in claim 1, wherein

the sleeve member is sealed with respect to the rotary body at each axial end of the rotary body.

9. The rotary machine as set forth in claim 1, wherein

the stator has a stator core and a coil attached to the stator core with a coil end part protruding from each end of the stator core and the rotary machine further comprises: a mold member formed at each end of the stator core, to cover a base part of the coil end part; and a partition member attached in contact with the mold member, to separate a first space in which the rotor is arranged from a second space in which the coil end part is arranged.

10. The rotary machine as set forth in claim 9, further comprising

a mold member arranged inside the stator core, to fill a gap in a slot that is formed in the stator core to accommodate the coil,

the mold member formed at each end of the stator core and the mold member arranged inside the stator core being made of different materials having different thermal conductivities.