JPH05316674A - Motor - Google Patents

Abstract

PURPOSE:To reduce the pressure loss of cooling air so as to improve the cooling efficiency of the cooling air by forming the openings of flowing-in and flowing- out ports of the flow passage of the cooling air composed of a plurality of through holes from one end of a frame to a rotor core or from one end of the frame to the other end of the frame through the rotor core by gradually increasing the diameters of the ports from the diameters of the through holes. CONSTITUTION:Cooling air flowing into ports 20 formed at one ends of a plurality of holes 19 formed through a rotor core 11 in parallel with the shaft 10 of the rotor 11, have diameters larger than those of the holes 19 at their end sections and are connected to the holes 19 by gradually reducing the diameters toward the holes 19. The diameters at the ends of cooling air flowing-out ports provided on the other end sides of the holes 19 are larger than those of the holes 19 and gradually increased from the holes 19. When flow passages 22 provided with the flowing-in ports 20, the diameters of which are gradually decreased toward the holes 19, and flowing-out ports 21, the diameters of which are gradually increased from the holes 19, at both ends are provided, the cooling efficiency of the cooling air can be improved, since the pressure loss of the cooling air can be reduced remarkably.

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 improved cooling characteristics.

[0002]

2. Description of the Related Art FIG. 7 shows, for example, a catalog "Mitsubishi Motor Drive Induction Motor" issued by Mitsubishi Electric Corporation in February 1989.
It is a side view which shows the conventional electric motor shown by AC6785-C in a cross section. In the figure, 1 is a cylindrical frame, 2
Is an end frame attached to one end of the frame 1, and has an intake port 2a opened toward the center on the outer peripheral portion. An end frame 3 is attached to the other end of the frame 1, and has an exhaust port 3a opened toward the center on the outer peripheral portion. 4 is a bearing provided in the center of the end frame 2, 5 is a bearing provided in the center of the end frame 3, 6 is a stator core attached to the inner periphery of the frame 1, 7 is a stator core 6 The iron core retainers attached to both sides in the axial direction, 8 is a stator coil attached to the stator iron core 7, and the stator 9 is constituted by the above 6 to 8. Reference numeral 10 is a rotor shaft rotatably supported by bearings 4 and 5, 11 is a rotor core attached to the rotor shaft 10, and a first flow path 14 is provided between the stator core 6 and a predetermined gap. Is formed. 12 is an iron core retainer provided at one end of the rotor iron core 11 in the axial direction, 13 is an iron core retainer provided at the other end of the rotor iron core 11, 15 is a rotor iron core 11 and the iron iron retainers 12, 13 are rotors. A plurality of holes are provided in the circumferential direction penetrating substantially parallel to the shaft 10, and 16 is a rotor core 11
The rotor conductor provided on the outer periphery of the
a is provided. Reference numeral 17 is a cooling fan attached to the rotor shaft 10. The rotor 18 is composed of 10 to 16 described above.

Next, the operation will be described. In FIG. 7, when the cooling fan 17 is rotated by driving the rotor shaft 10, air is exhausted from the exhaust port 3b, the inside of the frame 1 is in a negative pressure state, and the outside air is sucked from the intake port 2a. The electric motor is cooled by the cooling air passing through the first flow path 14 between the rotor 18 and the stator 9 and the air holes 15 provided in the rotor core 11. FIG. 8 is a characteristic diagram showing the capacity of the cooling fan 17 as a blower by the relationship between the air volume and the static pressure.
In the figure, N ₁ , N ₂ and N ₃ are curves showing the number of rotations of the motor, respectively, and have a relationship of N ₁ > N ₂ > N ₃ . A is a curve showing the relationship between the electric motor air volume and pressure loss, for example, Q ₂ is the intersection of the curve of the electric motor rotation speed N ₂ and the curve A, and the air volume / static pressure operating point when the electric motor rotation speed is N _2. Is. Thus, it will be ventilated in the range of intersection Q ₁ to Q ₃ in the rotational speed curve N ₁ to N ₃ and the curve A of the motor. In the electric motor of FIG. 7, the capacity of the cooling fan 17 as a blower is determined by the rotation speed. As shown in FIG. 8, when the rotation speed of the electric motor changes, the air volume and static pressure also change. However, the pressure loss increases and the air volume passing through the hole 15 decreases.

[0004]

Since the conventional electric motor is constructed as described above, the flow resistance of the cooling air increases and the pressure loss increases as the number of revolutions increases, so that the amount of air passing through the hole 15 increases. Therefore, there is a problem in that the cooling efficiency is reduced because

The present invention has been made to solve the above problems, and an object thereof is to obtain an electric motor which can reduce the pressure loss of the cooling air and improve the cooling efficiency.

[0006]

According to a first aspect of the present invention, there is provided a first motor in which cooling air introduced from one end of a frame is passed between a stator and a rotor and is discharged from the other end of the frame. , A plurality of holes penetrating the iron core of the rotor substantially in parallel with the first flow path, and the holes gradually decreasing from the openings provided at both ends of the hole and having a diameter larger than the diameter of the hole. The second flow path is formed by an inflow port connected to the hole and a discharge port whose diameter gradually increases from the hole.

According to a second aspect of the present invention, in the electric motor of the first aspect, the cooling air introduced from one end of the frame is passed between the stator and the rotor and discharged from the other end of the frame, the stator. A plurality of holes provided through the iron core in a manner substantially parallel to the first flow path, and openings that are provided at both ends of the hole and have a diameter larger than the diameter of the holes are gradually reduced and connected to the holes. The second flow path is formed by an inflow port and a discharge port whose diameter gradually increases from the hole.

According to a third aspect of the present invention, in the electric motor of the third aspect, the cooling air introduced from one end of the frame is passed through between the stator and the rotor and discharged from the other end of the frame, the rotor. A plurality of holes provided in the iron core and penetrating substantially parallel to the first flow path with a predetermined diameter, and connecting to the holes by gradually reducing from openings having a diameter larger than the diameter of the holes provided at both ends of the hole. Second flow path formed by the opened flow inlet and the discharge opening whose diameter is gradually enlarged from the hole, and a plurality of holes provided in the iron core of the stator and penetrating with a predetermined diameter substantially in parallel with the first flow path. No. 3, a third opening formed at both ends of the hole and connected to the hole by being gradually reduced from an opening having a diameter larger than the diameter of the hole, and a discharge opening having a diameter gradually increasing from the hole. And the flow path of.

[0009]

The inlet and the outlet of the second flow passage of the electric motor according to the present invention reduce the flow passage resistance and increase the flow rate and flow velocity of the cooling air flowing in the second flow passage.

[0010]

EXAMPLES Example 1. Embodiment 1 of the present invention will be described below with reference to the drawings. 1 is a partial side sectional view showing an electric motor according to Embodiment 1 of the present invention. In the figure, 1-14,
Since 16 and 17 are the same as the conventional ones, their description is omitted. A plurality of holes 19 are provided in the circumferential direction so as to penetrate the rotor core 11 substantially in parallel with the shaft 10 and a cooling air inlet 20 is provided at one end of the hole 19 and has a diameter of the end 19 The diameter is larger than the diameter of the hole, and the hole 19 is gradually reduced toward the hole 19 to be connected to the hole 19. 21 is an outlet for cooling air provided on the other end of the hole 19,
The diameter of the end portion is gradually enlarged from the hole 19 to a diameter larger than the diameter of the hole 19. A second flow path 22 having an inlet and a discharge port larger than the hole 19 is formed at both ends in the above 19 to 21, and the above 10 to 1 are formed.
The rotor 23 is composed of 3, 22.

Next, the operation will be described. The amount of cooling air of the electric motor depends on the pressure loss of the cooling air. This pressure loss is caused by a vortex or the like generated in the flow path of the cooling air and prevents the pressure energy from being converted into kinetic energy.
If this pressure loss is reduced, it is possible to increase the cooling air volume. As a standard for comparing the pressure loss, a method of expressing by the head of water is mentioned, and is shown by the following formula. h = ζ · V ₂ ² / 2g (1) where ζ: loss coefficient V ₂ : cooling air velocity in the cooling air wind hole g: gravitational acceleration When attention is paid to the loss coefficient ζ in equation (1), Two
In the conventional electric motor shown in (a), in the case of the hole 15 that is abruptly reduced inside the frame, the pressure drop is extremely large because the cross-sectional area changes abruptly, and eddy is generated near the entrance of the hole 15 to cause loss. Will grow. If it is considered that the cross-sectional area of the cooling air before the inlet of the hole 15 is extremely large as compared with the cross-sectional area of the hole 15, the above loss coefficient is about 0.5. Meanwhile, hole 19
FIG. 2 showing the flow channel of the present invention at the inlet of the (second flow channel).
As shown in (b), when the inlet 20 connected to the hole 19 is gradually reduced from a diameter larger than the diameter of the hole 19, the cross-sectional area of the second flow passage 22 through which the cooling air flows gradually changes. Therefore, the pressure drop due to the change in cross-sectional area is reduced, and the loss due to the generation of vortices is also significantly reduced. The cross-sectional area before the inlet of the second flow path 22 is
When the cross-sectional area of the second flow path 22 is extremely large, the loss coefficient ζ of the cooling air inlet 20 is about 0.18 or less. As described above, since the loss is reduced, the pressure energy is rapidly converted into velocity energy, and the pressure loss at the inflow port 20 of the second flow path 22 is reduced to 40% or less as compared with the conventional case. ..

The pressure loss on the outlet side of the conventional second flow path (air hole 15) is as follows. The inner diameter d ₁ of the rotor ring 16 shown in FIG. 3A is 200 mm, and the diameter d ₂ of the rotor shaft 10 is 8 mm.
In the case of a conventional rotor 18 having a diameter 0 of 0 mm and a diameter d _{3 of the} air hole 15 of 22 mm, if the velocity of the cooling air passing through the air hole 15 is V ₁ , the loss head in consideration of friction loss is calculated as follows. Like ^{_{h = 0.68 · V 1 2 /}} g ( although, g: gravitational acceleration) In contrast, as shown in FIG. 3 showing the flow path of the present invention (b), 22 mm is the diameter d ₃ of the air holes 19, air holes 19 Outlet from diameter d ₃
Assuming that the second flow path 22 is provided with the discharge port 21 that is gradually expanded to a diameter d ₄ = 25 mm of 21, the head loss is h = 0.35 · V ₁ ² / g. In the case of FIG. 3B, the pressure loss is significantly reduced to about 51% as compared with the conventional outlet of the hole 15. As described above, the inlet 20 and the hole 19 that are gradually reduced at both ends of the air hole 19
When the second flow path 22 is provided with the discharge port 21 that is gradually expanded from, the pressure loss is significantly reduced. Therefore, as shown in FIG. 4, the curve of the rotation speed N of the electric motor, the air flow rate of the electric motor, and the pressure loss. The intersection Q with the curve A indicating the relationship with (the air volume / static pressure operating point at the rotation speed N) moves to the air volume increasing side, so that the cooling air flowing in the second flow path increases. Note that FIG.
In the figure, A ₁ is the conventional air volume / pressure loss curve, A ₂ is the air volume / pressure loss curve according to the embodiment of the present invention, Q ₄ is the air volume / static pressure operating point at the conventional rotational speed N, and Q ₅ is the present invention. The relationship of Q ₅ > Q ₄ is formed at the air volume / static pressure operating point at the rotation speed N according to the embodiment of FIG.

Embodiment 2. FIG. 5 is a side sectional view showing an electric motor according to Embodiment 2 of the present invention. In the figure,
Since 8, 10, 14, 16, and 17 are almost the same as those of the conventional one shown in FIG. 7, description thereof will be omitted. Reference numeral 24 is a rotor core attached to the rotor shaft 10, and forms a first flow path 14 with a predetermined gap with the stator core 6. Reference numeral 25 is an iron core retainer provided on the rotor iron core 24, and 26 is an iron core retainer provided on the other end of the rotor iron core 24. The rotor 27 is composed of the above 10, 16, 24 to 26. 28 is provided in the stator core 6 and is the first flow path.
Hole that penetrates almost parallel to 14, 29 is a fixed iron core retainer 7 at one end
At the inlet provided in the hole, the hole gradually shrinks toward the hole 28.
Connected with 28. Reference numeral 30 denotes a discharge port provided in the fixed iron core retainer 7 at the other end, the diameter of which gradually increases from the hole 28. The above 28 to 30 form the second flow path 31, and the above 6 to 8 and 31 form the stator 32. In the electric motor of the second embodiment, since the flow passage resistance of the second flow passage becomes small, the flow rate of the cooling air flowing through the second flow passage increases, and together with the cooling air flowing through the first flow passage, the stator 32 To cool efficiently.

Example 3. FIG. 6 is a side sectional view showing an electric motor according to Embodiment 3 of the present invention. In the figure,
8, 10 to 14, 16, 17, 19 to 23 are the same as those in FIG. 1 showing the first embodiment, and 28 to 32 are the same as those in FIG. .. The electric motor according to the third embodiment is
The first flow path 14 formed between the rotor 21 and the stator 32
And the second formed on the rotor 21 with reduced flow resistance.
And the third flow path 31 formed in the stator 32 to efficiently cool both the rotor 21 and the stator 32.

Example 4. In the first to third embodiments, the case of the electric motor provided with the cooling fan 17 has been described, but the cooling air generated by the blower is supplied from the intake port 2a to the frame 1
The same effect can be obtained even when applied to an electric motor that is sent inside.

[0016]

As described above, according to the present invention, a plurality of holes are provided in the rotor or the stator substantially parallel to the first flow path, and the diameter of the holes provided at both ends of the holes. Since the second flow path is formed by the inlet that is gradually reduced from the opening having the larger diameter and is connected to the hole, and the outlet that is gradually enlarged from the hole in the diameter, the pressure of the cooling air is reduced. By reducing the loss and increasing the flow velocity of the cooling air, it is possible to obtain the electric motor capable of improving the cooling efficiency.

[Brief description of drawings]

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

FIG. 2 is a diagram showing an inflow state of cooling air at a cooling air inlet of a second flow path of the electric motor according to the first embodiment of the present invention in comparison with a conventional one.

FIG. 3 is a diagram showing a state in which cooling air is discharged from a cooling air discharge port of a second passage of the electric motor according to the first embodiment of the present invention in comparison with a conventional one.

FIG. 4 is a characteristic diagram showing a flow rate of cooling air of the electric motor according to the first embodiment of the present invention in comparison with a conventional one.

FIG. 5 is a side sectional view showing an electric motor according to Embodiment 2 of the present invention.

FIG. 6 is a side sectional view showing an electric motor according to Embodiment 3 of the present invention.

FIG. 7 is a side sectional view showing a conventional electric motor.

FIG. 8 is a blower characteristic diagram of a cooling fan of a conventional electric motor.

[Explanation of symbols]

 1 Frame 6 Stator Core 9 Stator 11 Rotor Core 14 First Flow Path (Gap) 19 Hole 20 Inlet 21 Discharge Port 22 Second Flow Path 23 Rotor

Claims (3)

[Claims] 1. A first flow path for passing cooling air introduced from one end of a frame between a stator and a rotor and discharging it from the other end of the frame, which is provided in the iron core of the rotor. A plurality of holes penetrating with a predetermined diameter substantially parallel to the first flow path, an inlet provided at one end of the hole and connected to the hole by gradually reducing from a diameter larger than the diameter of the hole, An electric motor having a second flow path, which is provided at the other end of the hole and is formed with a discharge port that gradually expands from the hole to a diameter larger than the diameter of the hole. 2. A first flow path for allowing cooling air introduced from one end of the frame to pass between the stator and the rotor and to be discharged from the other end of the frame, which is provided in the iron core of the stator. A plurality of holes penetrating with a predetermined diameter substantially parallel to the first flow path, an inlet provided at one end of the hole and connected to the hole by gradually reducing from a diameter larger than the diameter of the hole, An electric motor having a second flow path, which is provided at the other end of the hole and is formed with a discharge port that gradually expands from the hole to a diameter larger than the diameter of the hole. 3. A first flow path for passing cooling air introduced from one end of the frame between the stator and the rotor and discharging it from the other end of the frame, which is provided in the iron core of the rotor. A plurality of holes penetrating with a predetermined diameter substantially parallel to the first flow path, an inlet provided at one end of the hole and connected to the hole by gradually reducing from a diameter larger than the diameter of the hole, A second flow path formed at the other end of the hole and formed with a discharge opening that gradually expands from the hole to a diameter larger than the diameter of the hole, and substantially the same as the first flow path provided in the iron core of the stator. A plurality of holes penetrating with a predetermined diameter in parallel, an inlet provided at one end of the hole and connected to the hole by gradually reducing from a diameter larger than the diameter of the hole, and provided at the other end of the hole And a third flow path formed by a discharge opening that is gradually expanded from the hole to a diameter larger than the diameter of the hole. Equipped electric motor.