JP2013179732A - Motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor with a stator core having a polygonal-shaped external form in which cooling capability is made uniform over the entire stator core.SOLUTION: A motor 10 includes: a stator core 14 having a rotor housing hole 15 and a plurality of cooling channels 20 on an outer peripheral side of the rotor housing hole 15; and a rotor 18 disposed rotatably in the rotor housing hole 15. The stator core 14 configures a polygonal-shaped transverse cross section having a plurality of corners C1 to C8, and ribs respectively disposed between the plurality of cooling channels 20 (20-1 to 20-6) belonging to the corners C1 to C8, respectively, are formed so that an inclination toward the corner C1 is increased as separating from the corner C1.

Description

  The present invention relates to an electric motor provided with a cooling passage extending in an axial direction in a stator core, for example.

The electric motor includes a stator (stator) and a rotor (rotor). A rotor housing hole having a circular cross section is formed along the central axis of the stator, and the rotor is rotatably provided in the rotor housing hole.
In such an electric motor, a stator constructed by laminating a large number of thin electromagnetic steel plates is well known. In this stator, on the outer peripheral side of the rotor housing hole, a plurality of slots which are continuous in parallel with the central axis of the rotor housing hole are formed at intervals in the circumferential direction, and windings are wound around these slots a number of times. Is configured. The rotor is driven to rotate in the stator by the interaction between the magnetic field generated by energizing the winding and the magnetic field of the permanent magnet built in the rotor.

  During operation, the motor generates heat due to copper loss of the windings, iron loss of the stator core, and the like, and thus has a cooling structure for suppressing temperature rise. In the case of an electric motor having no casing covering the outside of the stator core (casingless or frameless), a cooling passage extending in the axial direction is provided on the outer peripheral portion of the stator core, and air is allowed to flow from one end (inlet) in the axial direction to the other end ( Some are cooled by discharging from the outlet.

Since the stator core has a structure in which electromagnetic steel sheets are laminated, the cooling passage is a hole having a predetermined shape. The cooling capacity is improved by devising specifications such as the shape, number and position of the cooling passages.
For example, in Patent Document 1, as shown in FIG. 7, in the stator core 400, the ribs 402 between adjacent cooling passages 401 correspond to the slots 403 that are winding grooves in a one-to-one correspondence, It is known that the cooling capacity is improved because all the heat generated in each slot 403 is transferred to the corresponding rib 402 and exchanged with cooling air.

Kaisho 59-59034

However, as in the example shown in FIG. 7, when the outer shape of the stator core 400 in the electric motor is a polygon, the cross-sectional area (opening area) of the cooling passage 401 is larger as it is closer to the corner C, and is smaller when it is away from the corner C. This is for ensuring the maximum cross-sectional area of the cooling passage 401 according to the area outside the slot 403. Therefore, a large amount of cooling air flows through the cooling passage 401 near the corner. Since the heat generation amount (copper loss) in each slot 403 and the iron loss of the stator core in the vicinity thereof are substantially equal, the cooling heat amount that each cooling passage 401 takes is also substantially equal. Therefore, in the cooling passage 401 far from the corner portion C, the air volume is smaller than that in the cooling passage 401 close to the corner portion C. Therefore, the temperature rise of the cooling air increases near the outlet of the cooling passage 401 and the cooling capacity is low.
Further, since the heat transfer area (circumferential length of the cooling passage 401) is small in the cooling passage 401 away from the corner C, the temperature difference between the heat transfer surface temperature (the temperature of the rib 402) and the cooling air is increased, and the cooling capacity is increased. Is low.
As described above, an electric motor including a stator core having a polygonal outer shape (an octagonal shape in FIG. 7) has a difference in cooling capacity in the circumferential direction. It is not easy to cool the area to the required temperature.
The present invention has been made on the basis of such a technical problem, and an object of the present invention is to improve cooling capacity by uniformly cooling the entire stator core in an electric motor including a stator core having a polygonal outer shape. .

An electric motor according to the present invention includes a rotor housing hole that is continuous along one direction, a stator core that has a plurality of cooling passages that are continuous along one direction on the outer peripheral side of the rotor housing hole, and a direction within the rotor housing hole. And a rotor provided so as to be rotatable about an axis extending along the axis.
In the electric motor of the present invention, the stator core has a polygonal cross section having a plurality of corners, and the ribs provided between the plurality of cooling passages belonging to each corner are separated from the corners. It is formed so that the inclination toward the corner is increased.
As will be described in detail later, the cooling capacity in the circumferential direction can be made uniform in an electric motor including a polygonal stator core by adopting a configuration in which the ribs provided between the cooling passages are inclined as described above.
In the electric motor of the present invention, it is preferable that the lengths of the inner edges of the plurality of cooling passages belonging to the respective corners are formed uniformly. By doing so, the amount of cooling heat that each cooling passage takes can be made uniform.

The electric motor of the present invention can specifically realize equalization of the cooling capacity in the circumferential direction by adopting at least one of the following three forms on the premise that the electric motor of the present invention has the above characteristics.
1st form: The some cooling passage which belongs to each corner | angular part is formed in each cross-sectional area equally.
Second mode: The plurality of cooling passages belonging to the respective corners are formed so as to have an equal circumference.
3rd form: The rib provided between the some cooling passages which belong to each corner | angular part is formed equally in each length.

In the electric motor of the present invention, it is preferable that the width of the rib provided between the plurality of cooling passages belonging to each corner is increased according to the length.
Further, in the electric motor of the present invention, the plurality of cooling passages belonging to each corner can be formed by being divided in the radial direction.

  ADVANTAGE OF THE INVENTION According to this invention, in the electric motor provided with a polygon-shaped stator core, the cooling capability in the circumferential direction can be equalized.

It is a perspective view which shows the external appearance of the electric motor in this Embodiment. It is a top view of a stator core. FIG. 3 is a partially enlarged view of FIG. 2. It is a top view of the other example of a stator core. It is a top view of the other example of a stator core. It is a top view of the other example of a stator core. It is a top view of the conventional stator core (patent document 1).

Hereinafter, the present invention will be described in detail based on the embodiments shown in FIGS.
As shown in FIG. 1, the electric motor 10 has a stator core 14 formed by laminating a plurality of electromagnetic steel plates 30 between a pair of plate-like bracket plates 11 and 12 positioned in parallel to each other.
As shown in FIGS. 2 and 3, the stator core 14 has a cylindrical rotor housing hole 15 having a central axis in the direction connecting the one bracket plate 11 and the other bracket plate 12. Yes. The stator core 14 has a substantially square outer shape, but the corners are cut into a rectangular shape.
At both ends of the stator core 14, end plates 16 are provided between the one bracket plate 11 and end plates 17 are provided between the other bracket plate 12.
In the rotor housing hole 15, a rotating shaft (not shown) whose both ends are rotatably supported by end plates 16 and 17 is provided on the central axis of the rotor housing hole 15. A rotor 18 having an annular cross section is provided on the rotating shaft. The outer peripheral surface of the rotor 18 faces the inner peripheral surface of the rotor housing hole 15 of the stator core 14. The rotor 18 includes a permanent magnet (not shown).

On the outer peripheral side of the rotor storage hole 15 formed in the stator core 14, a plurality of slots 13 that are continuous in parallel with the central axis of the rotor storage hole 15 are formed at intervals in the circumferential direction. Each slot 13 is formed along the radial direction. A coil (not shown) is formed on the outer peripheral side of the rotor housing hole 15 by winding the winding around the slot 13 many times. The rotor 18 is rotationally driven by the interaction between the magnetic field generated by energizing the winding of the coil (not shown) from the outside and the magnetic field of the permanent magnet of the rotor 18.
The stator core 14 is formed with bolt insertion holes 22 through which bolts for inserting and fastening a plurality of electromagnetic steel plates 30 between the bracket plates 11 and 12 and the end plates 16 and 17 are inserted.

Further, in the stator core 14, a plurality of cooling passages 20 are formed in the cooling component 23 on the outer peripheral side of the rotor housing holes 15 and the plurality of slots 13.
The cooling passage 20 is also formed continuously in the bracket plates 11 and 12 and the end plates 16 and 17. A fan 19 is attached to one bracket plate 11, and the air sent out from the fan 19 flows through the cooling passage 20, whereby the stator core 14 is cooled.

As shown in FIG. 3, each cooling passage 20 includes an inner edge 20 i disposed on the center side of the stator core 14, an outer edge 20 o facing the inner edge 20 i and disposed on the outer peripheral side of the stator core 14, and the inner edge 20 i and the outer edge 20 o. And a pair of side edges 20s connecting the two.
Here, the cooling passage 20 is identified as 20-1 to 20-6 from the side close to the corner C1. The stator core 14 basically has a quadrilateral cross-sectional shape, but its corners are cut into quadrilaterals, so that C1 to C8 and eight corners are formed as shown in FIG. Prepare. In the following description, the corner portion C1 shown in FIG. 3 is taken as an example.

The rib 21 between the cooling passage 20-1 and the cooling passage 20-2 closest to the corner C1 is formed along the radial direction of the stator core 14 (symbol d in FIG. 3).
Next, it can be easily understood that the rib 21 between the cooling passage 20-3 and the cooling passage 20-4 is inclined with respect to the radial direction. As for this rib 21, the outer peripheral side of the stator core 14 inclines toward the corner | angular part C1.
Further, the rib 21 between the cooling passage 20-5 and the cooling passage 20-6 is also inclined toward the corner C1, and the inclination is more than the rib 21 between the cooling passage 20-3 and the cooling passage 20-4. Is also big.
As described above, in the stator core 14 of the present embodiment, the inclination toward the corner C1 increases as the rib 21 between the adjacent cooling passages 20-1 to 20-6 moves away from the corner C1. As for the length of the rib 21, it becomes shorter as the distance from the corner portion C1 increases.
The same applies to the other corners C2 to C8.

  Here, the cooling passages 20-1 to 20-6 shown in FIG. 3 belong to the corner C1. That is, any of the cooling passages 20-1 to 20-6 is closer to the corner C1 than the other corners C2 to C8. Thus, in the present invention, the corner C to which the cooling passage 20 belongs is specified based on the distance from the corners C1 to C8. In FIG. 2, the corners C2 to C8 to which the cooling passage 20 belongs are added for reference.

In the cooling passages 20-1 to 20-6, the length of each inner edge 20i is formed uniformly. Therefore, the amount of cooling heat that each cooling passage 20-1 to 20-6 takes can be made uniform.
In the cooling passages 20-1 to 20-6, the distance from each inner edge 20i to the outer peripheral edge of the slot 13 is set to be equal. Further, in the cooling passages 20-1 to 20-6, the distance from the outer edge 20o to the outer peripheral edge of the stator core 14 is set evenly.

By the way, in this embodiment, in order to cool the stator core 14 uniformly as a whole, the following three forms can be adopted.
[First embodiment]
The cross-sectional areas (channel cross-sectional areas) of the cooling passages 20-1 to 20-6 are equalized.
If the cross-sectional area of the flow path becomes uniform, the flow rate of the cooling air flowing through the cooling passages 20-1 to 20-6 can be made substantially the same. Then, since the temperature rise of the cooling air becomes almost the same in any of the cooling passages 20-1 to 20-6, it is possible to suppress the local temperature rise and cool the stator core 14 uniformly as a whole. be able to.
Here, in this embodiment, “equal” or “substantially the same” means that the variation in the flow path cross-sectional area and the flow rate of the cooling air is within a range of about ± 20%, preferably ± 10%. Within the range. The same applies to the length of the inner edge 20i described above or the peripheral length of the cooling passage described below.

[Second form]
The circumference (heat transfer area) of each of the cooling passages 20-1 to 20-6 is made equal.
When the circumferential lengths (heat transfer areas) of the cooling passages 20-1 to 20-6 are equalized, the wall surface temperature (heat transfer surface temperature) of each cooling passage, that is, the temperature of each rib 21 becomes substantially the same. If it does so, since the temperature of the rib 21 will rise locally and the phenomenon that the temperature of a coil | winding rises by this can be suppressed, the stator core 14 can be cooled uniformly as a whole.

[Third embodiment]
The lengths of the ribs 21 between the cooling passages 20-1 to 20-6 of the cooling passages 20-1 to 20-6 are equalized.
Since the lengths of the ribs 21 are uniform, the circumferential length (heat transfer area) of each cooling passage can be made substantially the same. The heat is transmitted through the rib 21 toward the outer peripheral edge of the stator core 14, but since the length of the rib 21 is substantially the same, the amount of heat transfer is almost the same in each rib 21, and the heat transfer on the outer peripheral side of the cooling passage is performed. The surface (wall) temperature can be made uniform and heat can be exchanged efficiently.

Any one of the three forms described above can be adopted. As a precondition, the present embodiment is configured such that the rib 21 between the adjacent cooling passages 20-1 to 20-6 moves away from the corner C as the corner. The inclination toward C is increased. This is due to the following reason.
For example, it is assumed that any rib is formed along the radial direction as in the prior art (for example, Patent Document 1).
Even in this case, the above-described first to third embodiments can be adopted. However, for example, when trying to equalize the cross-sectional areas of the first mode, that is, the cooling passages, the cross-sectional area of the cooling passage 401 close to the corner C is large as shown in FIG. The sectional area of the cooling passage 401 is small. Therefore, in order to make the cross-sectional area of the cooling passage equal while the ribs remain along the radial direction, it is necessary to use the cross-sectional area of the cooling passage 401 farthest from the corner C as a reference. If it does so, since the absolute flow volume of the cooling air in each cooling passage 401 will decrease, absolute cooling capacity will become low. This can also be understood from the fact that an extra portion where the cooling passage 401 is not formed remains on the outer peripheral side of the cooling passage 401 close to the corner C. Here, only the first mode is mentioned, but the same applies to the second mode and the third mode.
As described above, when the cooling passage is formed along the radial direction, the first to third embodiments can be adopted. However, since the cross-sectional area of the cooling passage 401 is small, only a cooling capacity corresponding to that can be obtained. Can not.

On the other hand, according to the present embodiment, as is clear from FIGS. 2 and 3, the cooling passages 20-1 to 20-6 can be formed to extend to the vicinity of the outer periphery of the stator core 14. Can be maximized. Therefore, the absolute cooling capacity is higher than that of the conventional stator core 400 shown in FIG. The reason why such a high cooling capacity is obtained is that the inclination toward the corner C is increased as the rib 21 is separated from the corner C, and this is the gist of the present invention.
It should be noted that the specific degree of inclination of the rib 21 should be set based on specifications such as the size and shape of the stator core 14.

  The stator core 14 is obtained by laminating the electromagnetic steel plates 30 having the same shape as described above, and the electromagnetic steel plate 30 has holes corresponding to the slots 13, the rotor housing holes 15, and the cooling passages 20. Alternatively, a groove is formed.

  As described above, the electric motor 10 according to the present embodiment employs the first to third embodiments described above by increasing the inclination of the rib 21 toward the corner portion C as the rib 21 moves away from the corner portion C. In addition, the cooling passages 20-1 to 20-6 can be formed over a wide area of the cooling component 23. Moreover, since the lengths of the inner edges 20i of the cooling passages 20-1 to 20-6 are formed uniformly, the amount of cooling heat that each cooling passage 20-1 to 20-6 takes can be made uniform. Therefore, according to the electric motor 10, it is possible to obtain a uniform and high cooling capacity for the stator core 14 as a whole.

[Modification]
Hereinafter, some modified examples of the electric motor 10 (stator core 14) will be described with reference to FIGS.
In the stator core 14 described above, the corner portion C is cut out in a rectangular shape. However, the stator core 114 may be filled up to the corner portion C without providing a cut-out as shown in FIG. Also in the stator core 114, the cooling passage 120 (120-1 to 120-5) is inclined more toward the corner C as it gets away from the corner C.
In the case of the stator core 114 shown in FIG. 4, the rib 121 between the cooling passage 120-1 and the cooling passage 120-2 is long. The long rib 121 is preferably wider than the other ribs 121. When the rib width is wide, heat is more easily transmitted to the outer peripheral side. For this reason, the outer peripheral side of the stator core 114 also has the same temperature as the inner peripheral side, so that the cooling efficiency is improved. That is, since the temperature difference between the cooling air flowing in the cooling passage 120 and the rib 121 (stator core 114) can be reduced, the temperature rise of the winding (coil) can be suppressed.
In addition, description of the bolt insertion hole 22 is omitted.

Next, as shown in FIG. 5, the cooling passage 220 of the stator core 214 can be divided in the radial direction. By dividing, the heat transfer area of the cooling passage 220 increases, and the cooling capacity can be increased.
As described above, when the cooling passage 220 is divided in the radial direction, it is preferable to make the width of the rib 221 along the circumferential direction wider than that of the rib 221 located on the outer side. This is because heat is more easily transferred to the cooling passage 220 located on the outer peripheral side of the stator core, as in the case of increasing the width in the case of the long rib 121 described above.

The outer shape of the stator core can be octagonal like a stator core 314 shown in FIG.
In the case of the octagonal stator core 314, eight corners C are formed. As the cooling passage 320 belonging to each corner C moves away from the corners C, the inclination toward the corners C increases. Yes.

In addition to this, as long as it does not depart from the gist of the present invention, the configuration described in the above embodiment can be selected or changed to another configuration as appropriate.
For example, although the linear rib 21 is shown in the present embodiment, the present invention is not limited to this, and a curved rib may be used. In this case, the cooling passage defined by the rib is also curved.

DESCRIPTION OF SYMBOLS 10 Electric motor 11, 12 Bracket board 13 Slot 14, 114, 214, 314 Stator core 15 Rotor accommodating hole 16, 17 End plate 18 Rotor 19 Fan 20, 120, 220, 320 Cooling passage 20i Inner edge 20o Outer edge 20s Side edge 21, 121, 221 Rib 22 Bolt insertion hole 23 Cooling component 30 Magnetic steel sheet C, C1, C2, C3, C4, C5, C6, C7, C8 Corner

Claims (7)

A stator core having a rotor housing hole continuous along one direction, and a plurality of cooling passages continuous along the one direction on the outer peripheral side of the rotor housing hole;
An electric motor having a rotor rotatably provided around an axis along the one direction in the rotor housing hole,
The stator core is
Polygonal cross section with multiple corners,
Ribs provided between the plurality of cooling passages belonging to each of the corners are formed so that the inclination toward the corners increases as the distance from the corners increases.
An electric motor characterized by that. The plurality of cooling passages belonging to each of the corners are formed so that the length of each inner edge is uniform.
The electric motor according to claim 1. Each of the plurality of cooling passages belonging to each of the corners has a uniform cross-sectional area.
The electric motor according to claim 1 or 2. Each of the plurality of cooling passages belonging to each of the corners has a uniform circumferential length.
The electric motor according to any one of claims 1 to 3. The ribs provided between the plurality of cooling passages belonging to each of the corners are formed uniformly in length.
The electric motor according to any one of claims 1 to 4. Ribs provided between the cooling passages belonging to each of the corners,
Increase the width according to the length,
The electric motor according to any one of claims 1 to 4. The plurality of cooling passages belonging to each of the corner portions are formed by being divided in a radial direction.
The electric motor according to any one of claims 1 to 6.

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