JPH06335200A - Motor equipped with rotor cooling means - Google Patents

Abstract

PURPOSE:To provide a simple structure of rotor cooling means which can effectively suppress the temperature rise of a motor by positively cooling a rotor. CONSTITUTION:A motor 10 is equipped with a rotor 14 having a shaft 12, a stator 18 surrounding the rotor 14, and end housings 32 and 34 supporting the shaft 12 rotatably. A circular member 44 fixed to the end housing 32 in opposition to one end face in axial direction of the rotor 14 is equipped with a through hole 50, which leads to the passage 58 of the end housing 32, a circular cavity 46, and a plurality of through holes, which open toward the rotor 14. Cooling medium, which is pressurized and fed into the passage 58 of the end housing 32 from outside, is distributed and jet out into a motor through the circular member 44. Likewise, a circular member 60 is fixed to the end housing 34, and the cooling medium, which has absorbed the heat of the rotor 14, is collected through the circular member 60, and is discharged out of a motor from the passage 74 of the end housing 34.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor having a rotor cooling means.

[0002]

2. Description of the Related Art Conventionally, various cooling methods have been proposed in order to absorb heat generated by iron loss and copper loss in a stator and a rotor of an electric motor and suppress a temperature rise within an allowable range.
It is used. For example, in order to effectively cool the stator, a housing supporting the stator and a stator core provided with passages for a cooling medium are known. Further, in order to cool the rotor, a method in which air is fed into the electric motor by a fan attached to the rotor or the shaft is generally used.

In recent years, in the field of machine tools, higher speed and higher output of the rotary spindle have been demanded. An induction motor is generally used to drive the spindle.
There is a problem that the temperature rise remarkably increases due to the reduction of the diameter dimension accompanying the increase in speed and the increase in the current accompanying the increase in output. Therefore, in this type of induction motor (so-called spindle motor), it is necessary to provide a more effective cooling method in order to obtain a high output. In particular, in a built-in type spindle motor that is directly connected to the main shaft, heat generated by the rotor is directly transmitted to the main shaft, so it is necessary to effectively cool the rotor. A method of blowing compressed air to the rotor and a method of providing a cooling medium passage extending in the axial direction in the shaft have been implemented.

[0004]

As described above, with respect to the stator, which is the fixing element of the electric motor, the temperature rise is relatively easily and effectively suppressed by providing a cooling medium passage in the housing or the stator core. be able to.
On the other hand, it is difficult for the rotor, which is a movable element, to directly provide the cooling medium passage to the rotor core from the viewpoint of strength maintenance and the like. Depends on heat exchange. In particular, in a motor such as a built-in type spindle motor that requires effective rotor cooling, it is desirable to implement the more positive heat exchange method as described above. However,
In the case of the conventional built-in type spindle motor, it is difficult to sufficiently inject air into the gap between the rotor and the stator by the cooling method in which compressed air is blown to the rotor by an external device, and the efficiency is improved from the outer peripheral surface of the rotor. There is a problem that heat cannot be absorbed well. Further, the method of providing the cooling medium passage extending in the axial direction in the shaft requires a joint device for supplying the cooling medium to the rotating shaft,
There is a problem that the structure becomes complicated and the manufacturing cost increases.

It is an object of the present invention to provide an electric motor which has a rotor cooling means of a simple structure capable of positively cooling the rotor and effectively suppressing the temperature rise of the electric motor, and which can achieve high speed and high output. It is in.

[0006]

In order to achieve the above object, the present invention provides a rotor fixed to a shaft, a stator surrounding the rotor with an air gap, and a stator fixedly supporting the stator and via the shaft. In a motor including a housing means for rotatably supporting the rotor by a rotor and a rotor cooling means for supplying a cooling medium for absorbing heat of the rotor to the periphery of the rotor, the rotor cooling means is directed to one end surface in the axial direction of the rotor. Is provided in the housing means and is pressurized and fed from the outside of the housing means to the first passage. Cooling medium distribution passage means for discharging the supplied cooling medium from the first hole group, a second hole group opening toward the other axial end surface of the rotor, and the second hole group and the outside of the housing means. To communicate A second passage is provided in the housing means, and the second passage is depressurized from the outside of the housing means so that the second passage is discharged from the first hole group of the cooling medium distribution passage means and passed through the gap. Cooling medium, second
And a cooling medium collecting passage means for collecting through the group of holes and discharging from the second passage to the outside of the housing means.

[0007]

The cooling medium distribution passage means appropriately distributes and ejects the cooling medium pressurized and supplied from the outside of the housing means to the first passage toward the one axial end surface of the rotor from the first hole group. . As a result, the cooling medium enters the air gap between the rotor and the stator substantially uniformly over the entire circumference. At this time, by reducing the pressure in the second passage of the cooling medium collecting passage means,
The cooling medium easily passes through the narrow gap even when the rotor rotates at high speed, and reaches the other axial end surface of the rotor. In this way, the cooling medium that has exchanged heat with the outer peripheral surface of the rotor is positively discharged to the outside of the electric motor through the second hole group and the second passage of the cooling medium collecting passage means. It The cooling medium passing through the gap can also absorb the heat of the stator.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in more detail with reference to the preferred embodiments shown in the accompanying drawings. FIG. 1 shows an electric motor 10 having rotor cooling means according to an embodiment of the present invention. The electric motor 10 includes a shaft 12, a rotor 14 fixed to the shaft 12, a stator 18 surrounding the rotor 14 with an air gap 16 interposed therebetween, a stator 18 fixedly supported, and the rotor 14 rotatable via the shaft 12. And housing means 20 for supporting the same. The electric motor 10 can be configured as an induction motor used for a spindle motor of a machine tool, for example. In this case, the rotor 14 includes a rotor core 22 made of a laminated body of a large number of electromagnetic steel plates as shown in the figure.
And a conductor portion (only the end ring 24 is shown) incorporated in the rotor core 22 by die casting or the like. Similarly, the stator 18 includes a stator core 26 formed of a laminated body of a large number of electromagnetic steel plates, and a plurality of windings 28 wound around the stator core 26.

The housing means 20 includes a stator core 26.
A central housing 30 fixed to the outer peripheral surface of the central housing 30 and end housings 32 and 34 connected to the respective axial end portions of the central housing 30. End housing 3
2, 34 rotatably support the shaft 12 via bearings 36, respectively. Each wire end portion 38 of the winding wire 28 of the stator 18
Can be covered with a resin member 40 that is molded in an annular shape adjacent to each axial end surface of the stator core 26. Each resin member 40 is preferably placed in contact with the end housings 32, 34. Further, the resin material can be filled between a portion of the winding 28 other than the wire end portion 38 and a slot (not shown) of the stator core 26 that accommodates the portion. The flow path 42 of the cooling medium for absorbing the heat of the stator core 26 and the winding wire 28 via the housing means 20 and the resin member 40 has the central housing 3
0 and the end housings 32 and 34 are continuously formed.

The cooling medium distribution path means of the rotor cooling means of the electric motor 10 surrounds the shaft 12 and is fixed to the end housing 32 so as to face the one axial end surface (left side in the figure) of the rotor 14 and to be fixed thereto. A member 44 is provided. The annular member 44 is
As shown in FIGS. 1 and 2, an annular cavity 46 is provided inside.
Is an annular wall 48 that forms one axial end surface of the annular member 44.
A through hole 50 communicating with the annular cavity 46,
And an annular wall 52 forming the other axial end surface of the annular member 44.
And a plurality of through holes 54 communicating with the annular cavity 46. The annular wall 48 of the annular member 44 abuts on an annular shoulder portion 56 formed on the inner peripheral portion of the end housing 32, while the annular wall 52 is arranged to face one axial end surface of the rotor 14. Therefore, the plurality of through holes 54 formed in the annular wall 52 form a first hole group that opens toward one axial end surface of the rotor 14. A passage 58 is provided in the end housing 32 to connect the outer peripheral surface of the end housing 32 with the surface of the shoulder portion 56. 1 formed on the annular wall 48 of the annular member 44
The one through hole 50 communicates with the passage 58 at the shoulder 56.
The passage 58, the through hole 50, and the annular cavity 46 thus form a first passage that communicates the first group of holes with the outside of the housing means.

The cooling medium collecting passage means of the rotor cooling means of the electric motor 10 surrounds the shaft 12 and is fixed to the end housing 34 so as to face the other axial end surface (right side in the figure) of the rotor 14. The member 60 is provided. The annular member 60 is
As will be described later, it has the same structure as the annular member 44,
For the sake of explanation, each component is given a reference numeral different from that of the annular member 44. The annular member 60 includes an internal annular cavity 62.
An annular wall 66 having one through hole 64 communicating with the end wall 34 and an annular shoulder 68 formed on the inner periphery of the end housing 34.
An annular wall 72 having a plurality of through-holes 70 that are in contact with the annular cavity 62 and communicate with the annular cavity 62, is disposed so as to face the other axial end surface of the rotor 14 and is fixedly supported by the end housing 34. Therefore, the plurality of through holes 70 of the annular wall 72 form a second hole group that opens toward the other axial end surface of the rotor 14. The end portion housing 34 is provided with a passage 74 that connects the outer peripheral surface of the end portion housing 34 with the surface of the shoulder portion 68. One through hole 64 formed in the annular wall 66 of the annular member 60 communicates with the passage 74 at the shoulder 68. Therefore, the passage 74,
The through hole 64 and the annular cavity 62 form a second passage that connects the second hole group and the outside of the housing means.

As shown in FIG. 2, annular members 44 and 60.
Is divided by a dividing line 76 into a half portion 78 having annular walls 48 and 66 and a half portion 80 having annular walls 52 and 72, respectively. Therefore, the annular members 44, 6
Zero is formed by molding the respective half-body portions 78, 80 by casting, machining, etc., and then combining the two.

As shown in FIG. 1, the passage 58 provided in the end housing 32 is connected to a cooling medium feeding device 82 installed outside the electric motor 10. Cooling medium feeding device 82
Is the passage 5 of the end housing 32, such as a compressor
8 is a well-known device capable of pressurizing and feeding the cooling medium. The cooling medium sent to the passage 58 is the annular member 4
4 through the through holes 50 and the annular cavity 46, and are jetted from the plurality of through holes 54 toward the one axial end surface of the rotor 14 as appropriate.

Further, the passage 74 provided in the end housing 34 is connected to a cooling medium suction device 84 installed outside the electric motor 10. The cooling medium suction device 84 is a well-known device such as a vacuum device capable of sucking the cooling medium under reduced pressure from the passage 74 of the end housing 34.
The cooling medium ejected from the plurality of through holes 54 of the annular member 44 is narrowed by the operation of the cooling medium suction device 84.
6 easily reaches the other axial end surface of the rotor 14 and effectively absorbs the heat of the rotor 14 during its flow. The cooling medium thus heat-exchanged is collected through the through hole 70 of the annular member 60, further passes through the annular cavity 62 and the through hole 64, and is forcibly discharged from the passage 74 to the outside of the electric motor 10. To be done.

In the electric motor according to the present invention, since the cooling medium flows inside the electric motor, gas such as air is generally used. However, like the electric motor 10 of the illustrated embodiment, the stator 18 is used.
In the structure in which the winding 28 of is covered with resin,
The use of atomized cooling medium is also possible. Further, the electric motor according to the present invention can be applied to a synchronous electric motor and a DC electric motor, in addition to the induction electric motor.

[0016]

As is apparent from the above description, according to the present invention, the cooling medium is pressure-fed from the outside via the cooling medium distribution passage means arranged opposite to the one axial end surface of the rotor, and It is possible to positively supply the cooling medium to the periphery of the rotor and discharge it to the outside of the motor by sucking the cooling medium under reduced pressure from the outside through the cooling medium collecting passage means arranged opposite to the other axial end surface of the rotor. It will be possible. As a result, the heat exchange capacity by the cooling medium is improved, the rotor can be positively cooled, and the temperature rise of the electric motor can be effectively suppressed, the life of the electric motor bearing can be improved, and the speed and output can be increased. Will be easier. Moreover, since no special device such as hole drilling or joint device is required for the shaft,
Provided is an electric motor having a simple structure and a cooling means capable of suppressing an increase in cost.

[Brief description of drawings]

FIG. 1 is a sectional view of an electric motor according to an embodiment of the present invention.

2 (a) is an end view, FIG. 2 (b) is another end view, and FIG. 2 (c) is a sectional view taken along line II-II of the annular member in the electric motor of FIG.

[Explanation of symbols]

 12 ... Shaft 14 ... Rotor 16 ... Air gap 18 ... Stator 20 ... Housing means 22 ... Rotor core 26 ... Stator core 28 ... Winding 30 ... Central housing 32, 34 ... End housing 40 ... Resin member 42 ... Flow path 44, 60 ... Annular Members 46, 62 ... Annular cavities 50, 54, 64, 70 ... Through holes 58, 74 ... Passages 82 ... Cooling medium feeding device 84 ... Cooling medium suction device

Claims (1)

[Claims] 1. A rotor fixed to a shaft, a stator surrounding the rotor with an air gap interposed therebetween, a housing means for fixedly supporting the stator and rotatably supporting the rotor via the shaft, In a motor having a rotor cooling means for supplying a cooling medium that absorbs heat of the rotor to the periphery of the rotor, the rotor cooling means includes a first hole group that opens toward one axial end surface of the rotor. And a first passage communicating the first hole group with the outside of the housing means, the first passage being provided in the housing means, and being fed under pressure from the outside of the housing means to the first passage. Cooling medium distribution passage means for discharging a cooling medium from the first hole group, a second hole group opening toward the other axial end surface of the rotor, and the second hole group and the outside of the housing means. Second communicating with Is provided in the housing means, and the second passage is depressurized from the outside of the housing means, so that the cooling medium distribution passage means is provided with the first passage.
Cooling medium collecting passage means for collecting the cooling medium discharged from the group of holes and passing through the gap through the second group of holes and discharging the cooling medium to the outside of the housing means from the second passage. An electric motor equipped with a rotor cooling means.