JP7095764B1 - Rotating electric machine - Google Patents

Abstract

Kind Code: A1 A rotating electric machine is provided in which cooling oil can be spread over the outer periphery of a stator with a relatively simple configuration, and reduction in torque and iron loss can be suppressed. A rotating electric machine includes a cylindrical stator that accommodates a rotor inside and a coil that is wound on the inner peripheral side; and a housing having grooves formed in the inner peripheral surface facing the outer peripheral surface, and an oil passage formed by the outer peripheral surface of the stator and the grooves in the housing for flowing cooling oil to the outer periphery of the stator. The above-mentioned grooves are arranged in the intermediate portion of the stator and extend in the circumferential direction of the stator, and branch from the first groove and extend in the direction intersecting the first groove, and extend in the axial direction end portions of the stator. and a plurality of second grooves for directing cooling oil from the first grooves to. The second grooves are circumferentially spaced apart on the stator. [Selection drawing] Fig. 2

Description

The present invention relates to a rotary electric machine.

Conventionally, in order to improve the cooling efficiency of the coil wound around the stator core, a rotary electric machine has been proposed in which cooling oil is brought into contact with the outer periphery of the stator to cool the stator. For example, Patent Document 1 discloses a rotary electric machine in which a groove is carved on the outer periphery of a stator core to form a flow path of cooling oil in a circumferential direction or an axial direction between a frame and a stator.

Japanese Unexamined Patent Publication No. 2010-187490

In Patent Document 1, cooling oil is supplied from a plurality of locations in the circumferential direction of the stator in order to distribute the cooling oil to the outer periphery of the stator. Therefore, the layout and processing of the cooling oil supply pipe become complicated, and the manufacturing cost increases. For example, when the cooling oil supply port is provided for each of the plurality of grooves extending in the axial direction, the manufacturing cost of the rotary electric machine is further increased.

Further, in Patent Document 1, since the groove is formed on the outer periphery of the stator core, the magnetic flux density is partially increased in the vicinity of the groove on the outer periphery of the stator, and there is a concern that the torque of the rotary electric machine is lowered due to the saturation of the magnetic flux.

Further, when the stator is fastened to the frame of the rotary electric machine by shrink fitting, it is known that the compressive stress corresponding to the tightening allowance acts on the stator, which increases the iron loss of the motor. It is also requested to suppress it.

The present invention has been made in view of the above circumstances, and provides a rotary electric machine capable of distributing cooling oil to the outer periphery of a stator with a relatively simple configuration and suppressing a decrease in torque and iron loss. do.

In the rotary electric machine of one aspect of the present invention, the rotor is housed inside, the cylindrical stator around which the coil is wound on the inner peripheral side, and the stator are fitted to the outer peripheral surface of the stator to cover the stator from the outside. A housing having a groove formed on an inner peripheral surface facing the outer peripheral surface of the stator is provided, and an oil passage formed by an outer peripheral surface of the stator and a groove of the housing and flowing cooling oil is provided on the outer peripheral surface of the stator. The above-mentioned grooves are arranged in the middle portion of the stator, and extend in a direction in which a first groove extending in the circumferential direction of the stator and a branch from the first groove intersect with the first groove, and an axial end portion of the stator. Includes a plurality of second grooves, which guide the cooling oil from the first groove. The second grooves are arranged at intervals in the circumferential direction of the stator, and the arrangement interval in the circumferential direction of the second groove is equal to or less than the arrangement interval in the circumferential direction of the coil.

In the above rotary electric machine, the second groove may extend in the axial direction of the stator.
In the above-mentioned rotary electric machine, the cross-sectional area of the flow path formed by the first groove may be larger than the cross-sectional area of the flow path formed by the second groove .

In the rotary electric machine described above, the housing may have one oil supply passage that communicates with the first groove and guides the cooling oil to the first groove. Further, the cross-sectional area of the flow path formed by the second groove may be set to be larger on the downstream side away from the refueling passage than on the upstream side where the distance from the refueling passage is short.

According to the rotary electric machine according to one aspect of the present invention, the cooling oil can be distributed around the outer periphery of the stator with a relatively simple structure, and the decrease in torque and the iron loss can be suppressed.

It is a perspective view which shows the motor of this embodiment. It is a vertical sectional view of the motor of this embodiment. It is a perspective view of a housing. It is a perspective view which shows typically the shape of the 2nd oil passage in a motor. It is an axial sectional view which shows the circumferential flow path and the discharge flow path in an enlarged manner. It is a circumferential sectional view which shows the discharge flow path enlarged.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the embodiment, in order to make the explanation easy to understand, the structures and elements other than the main part of the present invention will be described in a simplified or omitted manner. Further, in the drawings, the same elements are designated by the same reference numerals. It should be noted that the shapes, dimensions, etc. of each element shown in the drawings are schematically shown, and do not indicate the actual shapes, dimensions, etc.

FIG. 1 is a perspective view showing a motor of the present embodiment, which is an example of a rotary electric machine. FIG. 2 is a vertical cross-sectional view of the motor 1 of the present embodiment. The motor 1 of the present embodiment is an inner rotor type motor, and includes a rotor 2, a stator 3, and a housing 4.

The rotor 2 is, for example, a magnet-embedded type or surface magnet type rotor. A shaft 5 is fitted in the center of the rotor 2 so as to pass through the iron core along the rotation axis Ax. In the following description, the circumferential direction centered on the rotation axis Ax is simply referred to as a circumferential direction, and the radial direction centered on the rotation axis Ax is simply referred to as a radial direction.

The stator 3 has a cylindrical stator core and is concentrically arranged on the outer periphery of the rotor 2 with a slight air gap. On the inner circumference of the stator core that houses the rotor 2 inward, a plurality of teeth (not shown) protruding inward in the radial direction toward the rotation axis Ax are provided in a comb-teeth shape at equal intervals in the circumferential direction. A coil 6 is wound between adjacent teeth (slots) of the stator core. The teeth and slots of the stator core both extend along the axial direction.

In the motor 1, the magnetic field on the stator 3 side is sequentially switched by the current control of the coil 6, so that the rotor 2 rotates about the rotation shaft Ax by the attractive force or the repulsive force with the magnetic field of the rotor 2.

The housing 4 is a housing having a cylindrical space in which one side and the other side in the axial direction are open. The stator 3 and the rotor 2 are arranged in the cylindrical space of the housing 4. The stator 3 is fitted to the inner circumference of the housing 4 by shrink fitting, and the housing 4 is attached so as to cover the outer peripheral surface of the stator 3. Further, a lid (not shown) that pivotally supports the shaft 5 is attached to one side and the other side of the housing 4, respectively, and the lid closes the openings on both sides of the housing 4. Both the housing 4 and each lid are manufactured by casting.

On the inner peripheral surface of the housing 4, as shown in FIG. 3, a first groove 4a for forming the circumferential flow path 14 described later and a second groove 4b for forming the discharge flow path 15 described later are formed. Is engraved. The second groove 4b also has a function of reducing the contact area with the stator 3 that is shrink-fitted to the inner circumference of the housing 4.

Further, the motor 1 has a first oil passage 11 and a second oil passage 12 through which cooling oil is circulated. The first oil passage 11 is an oil passage for spraying cooling oil to the coil end 6a of the coil 6, and the second oil passage 12 is an oil passage for flowing cooling oil to the outer periphery of the stator 3.

As shown in FIG. 2, the first oil passage 11 is arranged on the upper side in FIGS. 1 and 2 with respect to the stator 3, and extends in the housing 4 along the axial direction. The first oil passage 11 has an inlet 11a for receiving cooling oil from an oil pump (not shown). Shower heads (not shown) for spraying cooling oil on the coil ends 6a are attached to both ends of the first oil passage 11 on one side and the other side of the housing 4.

The second oil passage 12 has a connecting oil passage 13 formed in the housing 4, a circumferential flow path 14 formed between the housing 4 and the stator 3, and a plurality of discharge flow paths 15.

As shown in FIG. 2, the connecting oil passage 13 of the second oil passage 12 is arranged on the upper side of the motor 1, branches from the first oil passage 11 and extends downward. The connecting oil passage 13 communicates with the circumferential flow path 14 located radially inside the first oil passage 11, and serves as an oil supply passage for guiding cooling oil from the first oil passage 11 to the circumferential flow path 14. Take on the function. The connecting oil passage 13 may receive the cooling oil directly from the oil pump without passing through the first oil passage 11.

FIG. 4 is a perspective view schematically showing the shape of the second oil passage 12 in the motor 1. FIG. 5 is an enlarged axial sectional view showing the circumferential flow path 14 and the discharge flow path 15. FIG. 6 is a circumferential sectional view showing the discharge flow path 15 in an enlarged manner.

As shown in FIG. 5, the circumferential flow path 14 is formed by a first groove 4a (see FIG. 3) carved in the inner circumference of the housing 4 and an outer peripheral surface of the stator 3 shrink-fitted into the housing 4. Will be done. Further, as shown in FIGS. 5 and 6, the discharge flow path 15 has a second groove 4b (see FIG. 3) carved on the inner circumference of the housing 4 and an outer circumference of the stator 3 shrink-fitted into the housing 4. Formed by a face. Therefore, both the circumferential flow path 14 and the discharge flow path 15 face the outer peripheral surface of the stator 3.

The first groove 4a for forming the circumferential flow path 14 is arranged at the center in the axial direction of the housing 4, and is formed in an annular shape along the outer periphery of the stator 3. The circumferential flow path 14 has a function of guiding the cooling oil in the circumferential direction at the center of the stator 3 in the axial direction and supplying the cooling oil to each discharge flow path 15.

The discharge flow path 15 is a flow path formed on one side and the other side in the axial direction with the circumferential flow path 14 as a base end, respectively. A plurality of second grooves 4b for forming the discharge flow path 15 are arranged at equal intervals in the circumferential direction of the stator 3. Each second groove 4b branches from the first groove 4a and extends axially to one end or the other end of the housing 4. Therefore, the discharge flow path 15 can guide the cooling oil from the circumferential flow path 14 in the axial direction. When the housing 4 is formed by casting, it is easy to form the groove if the second groove 4b has a shape extending in the axial direction.

Further, although the stator 3 is shrink-fitted to the housing 4, as shown in FIG. 6, the stator 3 does not come into contact with the housing 4 at the position of the discharge flow path 15. A plurality of discharge flow paths 15 arranged in the circumferential direction also function as a space for reducing the contact portion between the stator 3 and the housing 4 in the circumferential direction and releasing the compressive stress acting on the stator 3 by shrink fitting. Therefore, the residual stress inside the stator 3 due to shrink fitting is relaxed by the discharge flow path 15, and the iron loss of the motor 1 can be suppressed.

Here, the specifications of the circumferential flow path 14 and the discharge flow path 15 are set as follows, for example, in consideration of the cooling effect of the coil 6 and the iron loss suppressing effect of the motor 1.

As for the temperature distribution of the coil 6, the temperature rises as the distance from the coil end 6a, which easily dissipates heat, increases, and the axial center in the slot generally becomes hot. Further, the flow rate of the circumferential flow path 14 needs to be larger than the flow rate of the discharge flow path 15 in order to distribute the cooling oil to the plurality of discharge flow paths 15. Therefore, the cross-sectional area of the circumferential flow path 14 is set to be larger than the cross-sectional area of the discharge flow path 15.

As a result, the flow rate of the cooling oil in the circumferential flow path 14 becomes larger than the flow rate of the cooling oil in the discharge flow path 15. Then, heat exchange with the cooling oil becomes easy at the high temperature portion (center in the axial direction) of the coil 6 in the slot, and the cooling capacity of the high temperature portion of the stator 3 can be improved. Further, since the cross-sectional area of the discharge flow path 15 is smaller than the cross-sectional area of the circumferential flow path 14, the flow rate of the cooling oil in the discharge flow path 15 becomes faster, and the coil 6 in the slot is made more efficient along the axial direction. Can be cooled.

Further, it is considered that the residual stress inside the stator 3 due to shrink fitting is higher in the thick portion of the tooth than in the thin portion of the slot. Therefore, in order to more appropriately relax the residual stress inside the stator 3, it is preferable to set the arrangement interval of the discharge flow paths 15 to be equal to or less than the arrangement interval of the slots of the stator 3. As a result, since one or more discharge flow paths 15 face each tooth, the residual stress at the tooth portion of the stator 3 can be relaxed substantially uniformly in the circumferential direction. As an example, in the case of a stator having 48 slots, it is preferable that the discharge flow paths 15 are arranged at intervals of 7.5 ° or less (360 ° / 48 = 7.5 °) in the circumferential direction.

Further, the positions of the discharge flow path 15 and the coil 6 may be aligned or deviated in the circumferential direction. For example, when the positions of the coil 6 and the discharge flow path 15 match in the circumferential direction, the distance from the discharge flow path 15 to the coil 6 becomes short, so that the cooling oil flowing through the discharge flow path 15 makes the coil 6 of the heat generation source efficient. Can be cooled to. On the other hand, from the viewpoint of relaxing the residual stress inside the stator 3 due to shrink fitting, it is preferable to arrange the discharge flow path 15 at the position of the teeth having a high residual stress. Therefore, the arrangement of the discharge flow path 15 may be appropriately adjusted in consideration of the cooling performance of the coil 6 and the degree of relaxation of the residual stress inside the stator 3.

Further, the cross-sectional area of the discharge flow path 15 may be different depending on the position in the circumferential direction. For example, when comparing the discharge flow path 15 on the upstream side near the connecting oil passage 13 and the discharge flow path 15 on the downstream side away from the connecting oil passage 13, it is difficult to send the cooling oil to the discharge flow path 15 on the downstream side. Further, as the distance passing through the circumferential flow path 14 becomes longer, the temperature of the cooling oil also rises due to heat exchange in the discharge flow path 15 on the downstream side.

Therefore, in order to increase the cooling efficiency of the discharge flow path 15 on the downstream side, the cross-sectional area of the discharge flow path 15 on the downstream side may be larger than the cross-sectional area of the discharge flow path 15 on the upstream side. According to the above configuration, in the discharge flow path 15 on the downstream side, the flow rate of the cooling oil increases as the cross-sectional area becomes relatively large, and the cooling performance is biased between the discharge flow paths 15 on the upstream side and the downstream side. Can be suppressed.

When increasing the cross-sectional area of the discharge flow path 15 on the downstream side as described above, the radial depth of the second groove 4b may be increased, or the circumferential width of the second groove 4b may be increased. You may. When the width of the second groove 4b in the circumferential direction is increased, the contact portion between the stator 3 and the housing 4 in the circumferential direction becomes smaller, which is advantageous in suppressing the residual stress inside the stator 3 due to shrink fitting. be.

Here, in the present embodiment, the stator 3 is cooled by the cooling oil as follows.
First, the cooling oil is supplied from the inlet 11a of the first oil passage 11 and flows toward both ends of the first oil passage 11. The cooling oil flowing from the first oil passage 11 to one side of the housing 4 passes through the shower head on one side and is sprayed from above to the coil end 6a on one side. Similarly, the cooling oil flowing from the first oil passage 11 to the other side of the housing 4 passes through the shower head on the other side and is sprayed from above to the coil end 6a on the other side. As a result, the cooling oil in contact with the coil end 6a takes heat, so that the coil end 6a is cooled.

Further, a part of the cooling unit flowing through the first oil passage 11 flows from the connecting oil passage 13 of the second oil passage 12 into the circumferential flow path 14. The cooling oil supplied from the connecting oil passage 13 to the upper side of the circumferential flow path 14 flows downward from both sides of the circumferential flow path 14 in the counterclockwise direction and the clockwise direction. As a result, the cooling oil is distributed over the entire circumferential direction of the circumferential flow path 14 at the axial center of the stator 3, and the axial center of the stator 3 is cooled by heat exchange with the cooling oil.

Further, the cooling oil in the circumferential flow path 14 branches from the circumferential flow path 14 and flows into each discharge flow path 15. The cooling oil flowing through the discharge flow path 15 flows toward one end or the other end of the housing 4 along the axial direction, and is discharged into the space on the coil end 6a side. The stator 3 is cooled from the outer periphery by the cooling oil flowing through each discharge flow path 15, so that the coil 6 in the slot is cooled along the axial direction. A part of the cooling oil discharged from the discharge flow path 15 comes into contact with the coil end 6a to cool the coil end 6a.

Then, the cooling oil sprayed from the upper side through the first oil passage 11 and the cooling oil discharged from the discharge flow path 15 of the second oil passage 12 are stored in the oil pan region near the bottom surface of the housing 4. The cooling oil is supplied again from the oil pan region on the bottom surface side to the inlet 11a of the first oil passage 11 by driving an oil pump (not shown).

Hereinafter, the effect of the motor 1 of the present embodiment will be described.
In the second oil passage 12 of the present embodiment, the cooling oil is flowed in the circumferential direction at the axial center of the stator 3 by the circumferential flow path 14 of the first groove 4a. Then, the discharge flow path 15 of the second groove 4b branches from the circumferential flow path 14 to allow the cooling oil to flow along the axial direction of the stator 3. As a result, the cooling oil can be distributed around the outer periphery of the stator 3, and the high temperature portion of the coil 6 in the slot can be cooled.

Further, in the second oil passage 12 of the present embodiment, if the cooling oil is supplied from the oil supply passage (connecting oil passage 13) at one upper side to the circumferential flow path 14, the cooling oil is distributed to the outer periphery of the stator 3. Can be made. Therefore, the configuration of the motor 1 of the present embodiment is simpler than the configuration of supplying cooling oil from a plurality of oil supply passages to the outer periphery of the stator, and the manufacturing cost can be suppressed.

Further, in the present embodiment, since the grooves 4a and 4b are formed on the housing 4 side to form the second oil passage 12 between the grooves 4a and 4b and the outer periphery of the stator 3, the outer peripheral surface of the stator 3 can be smoothed in the circumferential direction. .. Therefore, as compared with a configuration in which a groove is provided on the stator 3 side to allow cooling oil to flow, magnetic flux saturation in the stator 3 is less likely to occur, and a decrease in torque of the motor 1 can be suppressed.

Further, in the present embodiment, the residual stress inside the stator 3 due to shrink fitting is relaxed by the second grooves 4b arranged in the circumferential direction of the housing 4. Therefore, the iron loss of the motor 1 can be suppressed.

The present invention is not limited to the above embodiment, and various improvements and design changes may be made without departing from the spirit of the present invention.

In the above embodiment, the configuration example of the motor 1 has been described as an example of the rotary electric machine, but the rotary electric machine of the present invention can also be applied to a generator.

In the above embodiment, a configuration example in which the discharge flow path 15 extends in parallel along the axial direction has been described. However, the rotary electric machine of the present invention may have a skew-shaped configuration in which the discharge flow path 15 extends in parallel in a direction inclined with respect to the axial direction.

In the above embodiment, an example in which the circumferential flow path 14 is arranged at the center of the stator 3 in the axial direction has been described. However, the rotary electric machine of the present invention may include a configuration in which the position of the circumferential flow path 14 is deviated from the axial center of the stator 3. That is, the circumferential flow path 14 may be formed in an intermediate portion excluding the axial end portion of the stator 3.

In the above embodiment, a configuration example in which the circumferential flow path 14 is formed in an annular shape in the circumferential direction has been described. However, in the rotary electric machine of the present invention, the circumferential flow path may not be provided in the entire circumferential direction, and for example, there may be a portion on the lower side where the circumferential flow path is not formed.

In addition, the embodiments disclosed this time should be considered to be exemplary and not restrictive in all respects. The scope of the present invention is shown by the scope of claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 ... motor, 2 ... rotor, 3 ... stator, 4 ... housing, 4a ... first groove, 4b ... second groove, 5 ... shaft, 6 ... coil, 6a ... coil end, 11 ... first oil passage, 11a ... inlet, 12 ... second oil passage, 13 ... connecting oil passage, 14 ... circumferential flow path, 15 ... discharge flow path

Claims (5)

A cylindrical stator that houses the rotor inside and a coil is wound around the inner circumference.
A housing that is fitted to the outer peripheral surface of the stator to cover the stator from the outside and has a groove formed on the inner peripheral surface facing the outer peripheral surface of the stator is provided.
It is formed by the outer peripheral surface of the stator and the groove of the housing, and has an oil passage for flowing cooling oil on the outer periphery of the stator.
The groove is
A first groove arranged in the middle of the stator and extending in the circumferential direction of the stator,
A plurality of second grooves that branch from the first groove and extend in a direction intersecting the first groove, and guide the cooling oil from the first groove to the axial end portion of the stator. Including,
The second groove is arranged at intervals in the circumferential direction of the stator .
The arrangement interval in the circumferential direction of the second groove is equal to or less than the arrangement interval in the circumferential direction of the coil.
A rotating electric machine characterized by that. The rotary electric machine according to claim 1, wherein the second groove extends in the axial direction of the stator. The rotary electric machine according to claim 1 or 2, wherein the cross-sectional area of the flow path formed by the first groove is larger than the cross-sectional area of the flow path formed by the second groove. The one according to any one of claims 1 to 3 , wherein the housing has one oil supply passage that communicates with the first groove and guides the cooling oil to the first groove. Rotating electric machine. The claim is characterized in that the cross-sectional area of the flow path by the second groove is set larger on the downstream side away from the refueling passage than on the upstream side where the distance from the refueling passage is short. 4. The rotary electric machine according to 4.

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