Electric motor

Abstract

To provide an electric motor with a cooling structure improved.SOLUTION: An electric motor includes: a rotor; a bearing that supports a shaft; and a stator disposed radially outward of the rotor via an air gap. The rotor has: a rotor core; a plurality of rotor bars; and an end ring that electrically connects the rotor bars. The stator has: a stator core; and a stator coil wound around the stator core. The stator coil has a coil end. The shaft has a first flow path extending from an axial other-side end to an axial one-side end, through which cooling oil flows. The shaft has: a second flow path extending from the first flow path toward the end ring and passing through the shaft; a third flow path extending from the first flow path toward the coil end and passing through the shaft; and a fourth flow path extending from the first flow path toward the bearing and passing through the shaft.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an electric motor.

Background Art

[0002] Conventionally, a technique for cooling the coil ends of a stator of a rotating machine is known. Patent Document 1 discloses a structure having an inclined surface for guiding cooling oil injected from an injection nozzle of a shaft to the coil ends in a dynamo as a rotating machine.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Rotating machines are known to generate heat during rotation. Since heat generation causes deterioration of rotational efficiency and affects the heat resistance and lifespan of components, it is important to cool the rotating machine.

[0005] However, in Patent Document 1, the cooling oil is only guided from the shaft toward the coil ends, and there is no disclosure regarding the cooling of parts other than the coil ends of the stator. For this reason, it is not possible to sufficiently cool parts other than the coil ends of the rotating machine, and there is room for improvement in the cooling structure of the rotating machine.

[0006] An object of the present invention is to improve the cooling structure of an electric motor as a rotating machine.

Means for Solving the Problems

[0007] The motor according to one aspect of the present invention includes a rotor having a shaft extending along a central axis, a bearing for pivotally supporting the shaft, and a stator disposed via an air gap on the radially outer side of the rotor. The rotor includes a rotor core, rotor bars extending axially within the rotor core and arranged in a plurality in the circumferential direction, and an end ring for electrically connecting the rotor bars to each other. The stator includes a stator core and a stator coil wound around the stator core. The stator coil has coil ends. The shaft has a first flow path through which cooling oil flows and extends from the other axial end to one axial side. The shaft has a second flow path extending from the first flow path toward the end ring and penetrating the shaft, a third flow path extending from the first flow path toward the coil end and penetrating the shaft, and a fourth flow path extending from the first flow path toward the bearing and penetrating the shaft.

[0008] The motor according to one aspect of the present invention includes a rotor having a shaft extending along a central axis, a bearing for pivotally supporting the shaft, and a stator disposed via an air gap on the radially outer side of the rotor. The rotor has a plurality of permanent magnets inserted axially therein. The stator includes a stator core and a stator coil wound around the stator core. The stator coil has coil ends. The shaft has a first flow path through which cooling oil flows and extends from the other axial end to one axial side. The shaft has a second flow path extending from the first flow path toward the coil end and penetrating the shaft, and a third flow path extending from the first flow path toward the bearing and penetrating the shaft.

[0009] In the motor of the above aspect, the third flow path has a fifth flow path extending radially outward from the first flow path and a sixth flow path extending from the radially outer end of the fifth flow path toward the coil end and penetrating the shaft. The fourth flow path has the fifth flow path and a seventh flow path extending from the radially outer end of the fifth flow path toward the bearing and penetrating the shaft.

[0010] In the electric motor according to the above-described aspect, the flow path lengths of the fifth flow path, the sixth flow path, and the seventh flow path are the same.

[0011] In the electric motor according to the above-described aspect, the bearing is an open-type bearing.

Advantages of the Invention

[0012] According to one aspect of the present invention, the cooling structure of an electric motor as a rotating machine is improved.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0014] Hereinafter, a rotating electric machine according to an embodiment of the present invention will be described with reference to the drawings. In the following drawings, in order to make each configuration easier to understand, the actual structure, the scale, the number, etc. in each structure may be made different.

[0015] Also, in the drawings, an XYZ coordinate system is shown as a three-dimensional orthogonal coordinate system as appropriate. In the XYZ coordinate system, the X-axis direction is a direction parallel to the axial direction of the central axis J shown in FIG. 1. The Z-axis direction is the vertical direction in FIG. 2 among the radial directions with respect to the central axis J. The Y-axis direction is a direction orthogonal to both the X-axis direction and the Z-axis direction. In any of the X-axis direction, the Y-axis direction, and the Z-axis direction, the side pointed to by the arrow shown in the figure is the + side, and the opposite side is the - side.

[0016] In the following description, the positive side (+X side) in the X-axis direction is referred to as "one side", and the negative side (-X side) in the X-axis direction is referred to as "the other side". Note that the one side and the other side are merely names used for the purpose of explanation and do not limit the actual positional relationship and direction. Also, unless otherwise specified, the direction parallel to the central axis J (X-axis direction) is simply referred to as the "axial direction", the radial direction centered on the central axis J is simply referred to as the "radial direction", and the circumferential direction centered on the central axis J, that is, around the axis of the central axis J is simply referred to as the "circumferential direction". The side approaching the central axis J in the radial direction is referred to as the "radial inner side", and the side moving away from the central axis J is referred to as the "radial outer side".

[0017] In this specification, "extending in the axial direction" includes not only the case of strictly extending in the axial direction (X-axis direction), but also the case of extending in a direction inclined within a range of less than 45° with respect to the axial direction. Also, in this specification, "extending in the radial direction" includes not only the case of strictly extending in the radial direction, that is, in a direction perpendicular to the axial direction (X-axis direction), but also the case of extending in a direction inclined within a range of less than 45° with respect to the radial direction. Also, "parallel" includes not only the case of being strictly parallel, but also the case of being inclined at an angle of less than 45° with respect to each other.

[0018] <First Embodiment> FIG. 1 is a perspective view of a motor according to a first embodiment of the present invention. The motor 100 in FIG. 1 is an example of an electric motor. The motor 100 includes a rotor 170 (see FIG. 2) having a shaft 140 extending along a central axis J, a stator 160 (see FIG. 2) disposed on the outer side in the radial direction of the rotor 170 with an air gap therebetween, and a motor case 110 that houses the stator 160.

[0019] The motor case 110 is a cylindrical member. The motor 100 has a bracket 120 on one axial side of the motor case 110. The bracket 120 is fixed to the motor case 110 with bolts so as to close the opening on one axial side of the motor case 110. The motor 100 has a bracket 130 on the other axial side of the motor case 110. The bracket 130 is fixed to the motor case 110 with bolts so as to close the opening on the other axial side of the motor case 110.

[0020] The motor 100 has a supply pipe 150 fitted to the shaft 140 on the other axial side of the shaft 140. The supply pipe 150 is a tubular member and serves as a supply port for supplying cooling oil to the shaft 140.

[0021] Figure 2 is a side sectional view of the motor 100 in FIG. 1 cut along a plane passing through the central axis J and perpendicular to the Y axis, as viewed from the -Y side. The shaft 140 is fixed to the rotor 170. The shaft 140 is rotatable about the central axis J as the rotation axis. The shaft 140 is supported by a bearing 146a on one axial side of the rotor 170 and by a bearing 146b on the other axial side of the rotor 170. The bearings 146a and 146b are open-type bearings.

[0022] The rotor 170 includes a rotor core 171, rotor bars 172 that extend axially within the rotor core 171 and are arranged in a plurality in the circumferential direction, an end ring 173a that electrically connects the plurality of rotor bars 172 to each other on one axial side of the rotor core 171, and an end ring 173b that electrically connects the plurality of rotor bars 172 to each other on the other axial side of the rotor core 171.

[0023] The stator 160 includes a stator core 161 and a stator coil 162 wound around the stator core 161. The stator coil 162 has a coil end 162a that is exposed from the stator core 161 on one axial side of the stator core 161. The stator coil 162 has a coil end 162b that is exposed from the stator core 161 on the other axial side of the stator core 161.

[0024] The shaft 140 has a flow path 141 through which the cooling oil flows. The flow path 141 extends axially from the other end on the axial direction side of the shaft 140 to the one side in the axial direction. The flow path 141 is coaxial with the shaft 140. The shaft 140 has an opening of the flow path 141 at the other end on the axial direction side. The supply pipe 150 is inserted and fitted into the opening at the other end on the axial direction side of this flow path 141. A pump for generating the flow of the cooling oil, a heat exchanger for cooling the cooling oil, etc. are connected to the other end on the axial direction side of the supply pipe 150. The cooling oil flows into the motor 100 through this supply pipe 150. The cooling oil flows axially to the one side in the flow path 141. The flow path 141 does not penetrate the one end on the axial direction side of the shaft 140.

[0025] The shaft 140 has a flow path 142a that penetrates radially outward from the flow path 141 of the shaft 140. The axial position of the flow path 142a coincides with the axial position of the end ring 173a, and the cooling oil flowing through the flow path 141 is jetted toward the end ring 173a through the flow path 142a. The flow path 142a extends from the flow path 141 toward the end ring 173a and penetrates the shaft 140. The cooling oil flowing through the flow path 141 is appropriately supplied to the end ring 173a from the flow path 142a by receiving the supply pressure from the supply pipe 150 and the centrifugal force accompanying the rotation of the shaft 140, and can cool the end ring 173a. The shaft 140 has four flow paths 142a at equal intervals in the circumferential direction. The number of the flow paths 142a may be one or more.

[0026] The shaft 140 has a flow path 142b that penetrates the shaft 140 radially outward from the flow path 141. The axial position of the flow path 142b coincides with the axial position of the end ring 173b, and the cooling oil flowing through the flow path 141 is injected toward the end ring 173b through the flow path 142b. The flow path 142b extends from the flow path 141 toward the end ring 173b and penetrates the shaft 140. The cooling oil flowing through the flow path 141 receives the supply pressure from the supply pipe 150 and the centrifugal force associated with the rotation of the shaft 140, and thus is appropriately supplied from the flow path 142b to the end ring 173b, and can cool the end ring 173b. The shaft 140 has four flow paths 142b at equal intervals in the circumferential direction. The number of the flow paths 142b may be one or more.

[0027] The shaft 140 has a flow path 143a and a flow path 144a that penetrate the shaft 140 radially outward from the flow path 141. The flow path 143a extends radially outward from the flow path 141. The flow path 144a extends radially outward from the radially outer end of the flow path 143a so as to penetrate the shaft 140. The direction in which the flow path 144a extends is the same as the direction in which the flow path 143a extends. The flow path shape and the flow path diameter of the flow path 144a are the same as those of the flow path 143a. The flow path shape and the flow path diameter are the shape and the diameter of the flow path in a plane orthogonal to the direction in which the cooling oil flows.

[0028] The axial positions of the flow path 143a and the flow path 144a coincide with the axial position of the coil end 162a, and the cooling oil flowing through the flow path 141 is injected toward the coil end 162a through the flow path 143a and the flow path 144a. The flow path 143a and the flow path 144a extend from the flow path 141 toward the coil end 162a and penetrate the shaft 140. The cooling oil flowing through the flow path 141 receives the supply pressure from the supply pipe 150 and the centrifugal force associated with the rotation of the shaft 140, and thus is appropriately supplied from the flow path 143a and the flow path 144a to the coil end 162a, and can cool the coil end 162a. The shaft 140 has four combinations of the flow path 143a and the flow path 144a at equal intervals in the circumferential direction. The number of the combinations of the flow path 143a and the flow path 144a may be one or more.

[0029] The shaft 140 has a flow path 143b and a flow path 144b that penetrate the shaft 140 radially outward from the flow path 141. The flow path 143b extends radially outward from the flow path 141. The flow path 144b extends radially outward so as to penetrate the shaft 140 from the radially outer end of the flow path 143b. The direction in which the flow path 144b extends is the same as the direction in which the flow path 143b extends. The flow path shape and the flow path length of the flow path 144b are the same as those of the flow path 143b.

[0030] The axial positions of the flow path 143b and the flow path 144b coincide with the axial position of the coil end 162b, and the cooling oil flowing through the flow path 141 is injected toward the coil end 162b through the flow path 143b and the flow path 144b. The flow path 143b and the flow path 144b extend from the flow path 141 toward the coil end 162b and penetrate the shaft 140. The cooling oil flowing through the flow path 141 is appropriately supplied to the coil end 162a from the flow path 143b and the flow path 144b by receiving the supply pressure from the supply pipe 150 and the centrifugal force accompanying the rotation of the shaft 140, and the coil end 162b can be cooled. The shaft 140 has four combinations of the flow path 143b and the flow path 144b at equal intervals in the circumferential direction. The number of combinations of the flow path 143b and the flow path 144b may be one or more.

[0031] The shaft 140 has a flow path 145a that penetrates the shaft 140 outward from the flow path 143a. The flow path 145a extends outward from the shaft 140 so as to penetrate the shaft 140 from the radially outer end of the flow path 143a. The direction in which the flow path 145a extends is different from the direction in which the flow path 143a extends. The flow path shape and the flow path length of the flow path 145a are the same as those of the flow path 143a. The direction in which the flow path 145a extends is the same as the direction in which a straight line connecting the radially outer end of the flow path 143a and the bearing 146a extends. The flow path 143a branches into a flow path 144a and a flow path 145a at its radially outer end.

[0032] The cooling oil flowing through the flow path 141 is jetted toward the bearing 146a through the flow paths 143a and 145a. The flow paths 143a and 145a extend from the flow path 141 toward the bearing 146a and penetrate the shaft 140. The cooling oil flowing through the flow path 141 is appropriately supplied to the bearing 146a from the flow paths 143a and 145a by receiving the supply pressure from the supply pipe 150 and the centrifugal force accompanying the rotation of the shaft 140. The cooling oil supplied to the bearing 146a cools the bearing 146a and also contributes to the lubrication of the bearing 146a which is an open type bearing. The shaft 140 has four combinations of the flow paths 143a and 145a at equal intervals in the circumferential direction. The number of combinations of the flow paths 143a and 145a may be one or more.

[0033] The shaft 140 has a flow path 145b that penetrates the shaft 140 from the flow path 143b to the outside of the shaft 140. The flow path 145b extends to the outside of the shaft 140 so as to penetrate the shaft 140 from the radially outer end of the flow path 143b. The direction in which the flow path 145b extends is different from the direction in which the flow path 143b extends. The flow path shape and the flow path diameter of the flow path 145b are the same as those of the flow path 143b. The direction in which the flow path 145b extends is the same as the direction in which a straight line connecting the radially outer end of the flow path 143b and the bearing 146b extends. The flow path 143b branches into a flow path 144b and a flow path 145b at its radially outer end.

[0034] The cooling oil flowing through the flow path 141 is jetted toward the bearing 146b through the flow paths 143b and 145b. The flow paths 143b and 145b extend from the flow path 141 toward the bearing 146b and penetrate the shaft 140. The cooling oil flowing through the flow path 141 is appropriately supplied to the bearing 146b from the flow paths 143b and 145b by receiving the supply pressure from the supply pipe 150 and the centrifugal force accompanying the rotation of the shaft 140. The cooling oil supplied to the bearing 146b cools the bearing 146b and also contributes to the lubrication of the bearing 146b which is an open type bearing. The shaft 140 has four combinations of the flow paths 143b and 145b at equal intervals in the circumferential direction. The number of combinations of the flow paths 143b and 145b may be one or more.

[0035] Incidentally, if the supply amount of the cooling oil to the bearings 146a and 146b is too large, the bearing performance may not be fully exhibited. In the present embodiment, in order to avoid this, the flow paths 145a and 145b do not extend straight along the radial direction, but extend in the radial direction while inclining in the axial direction. With such a structure, due to the difference in centrifugal force accompanying the rotation of the shaft 140, the amount of cooling (lubricating) oil flowing through the flow paths 145a and 145b becomes less than the amount of cooling oil flowing through the flow paths 144a and 144b. The amount of cooling (lubricating) oil flowing through the flow paths 145a and 145b is an amount that can fully exhibit the bearing performance and is also an amount necessary for cooling the bearings.

[0036] The flow path diameters of the flow paths 142a, 142b, 143a, 143b, 144a, 144b, 145a, and 145b are each smaller than the flow path diameter of the flow path 141.

[0037] The flow path diameter of the flow path 145a is preferably equal to the flow path diameters of the flow paths 143a and 144a. The flow path diameter of the flow path 145b is preferably equal to the flow path diameters of the flow paths 143b and 144b. By doing so, both the ejection of the cooling oil from the flow paths 144a and 144a and the ejection of the cooling oil from the flow paths 145a and 145b can be performed well.

[0038] In the first embodiment, the case where the present invention is applied to an induction motor in which the rotor 170 has the rotor bar 172 and the end rings 173a and 173b has been described, but the present invention is not limited thereto. For example, the present invention can also be applied to a synchronous motor including a rotor having a plurality of permanent magnets inserted in the axial direction thereof. When the present invention is applied to a synchronous motor, the flow paths 142a and 142b for supplying the cooling oil toward the end rings become unnecessary.

[0039] The present invention is not limited to the above-described embodiments, and various improvements and design changes may be made without departing from the spirit of the present invention. In addition, the embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The scope of the present invention is indicated by the scope of claims rather than the above description, and it is intended that all changes within the meaning and scope equivalent to the scope of claims are included.

Explanation of Signs

[0040] 100... motor, 140... shaft, 141, 142a, 142b, 143a, 143b, 144a, 144b, 145a, 142b... flow paths, 146a, 146b... bearings, 160... stator, 162... stator coil 162a, 162b... coil ends, 170... rotor, 173a, 173b... end rings

Claims

1. A rotor having a shaft extending along a central axis, a bearing for pivotally supporting the shaft, a stator disposed via an air gap on the radially outer side of the rotor, and comprising: The rotor has a rotor core, rotor bars extending axially and arranged in a plurality in the circumferential direction within the rotor core, and an end ring for electrically connecting the rotor bars to each other. The stator has a stator core and a stator coil wound around the stator core. The stator coil has coil ends. The shaft has a first flow path extending from the other axial end to one axial side through which cooling oil flows. The shaft has a second flow path extending from the first flow path toward the end ring and penetrating the shaft, a third flow path extending from the first flow path toward the coil ends and penetrating the shaft, and a fourth flow path extending from the first flow path toward the bearing and penetrating the shaft. A motor characterized by the above.

2. A rotor having a shaft extending along a central axis, a bearing for pivotally supporting the shaft, a stator disposed via an air gap on the radially outer side of the rotor, and comprising: The rotor has a plurality of permanent magnets inserted axially therein. The stator has a stator core and a stator coil wound around the stator core. The stator coil has coil ends. The shaft has a first flow path extending from the other axial end to one axial side through which cooling oil flows. The shaft has a second flow path extending from the first flow path toward the coil ends and penetrating the shaft, and a third flow path extending from the first flow path toward the bearing and penetrating the shaft. An electric motor characterized by the following.

3. The third flow path has a fifth flow path extending radially outward from the first flow path, and a sixth flow path extending from the radially outer end of the fifth flow path toward the coil end and penetrating the shaft. The fourth flow path has the fifth flow path and a seventh flow path extending from the radially outer end of the fifth flow path toward the bearing and penetrating the shaft. The electric motor according to claim 1 or 2, characterized by the above.

4. The flow path diameters of the fifth flow path, the sixth flow path, and the seventh flow path are the same. The electric motor according to claim 3, characterized by the above.

5. The bearing is an open-type bearing. The electric motor according to claim 1 or 2, characterized by the above.

Images