JPH05292702A - Induction motor - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain an induction motor that can obtain high output without increasing the size. [Structure] A first flow path 31 for passing cooling air introduced from one end of a frame 24 between a stator 26 and a rotor 22 and discharging it from the other end of the frame 24, and a first flow path 31. A second flow path 32 communicating with each other, a high-pressure air supply device that supplies high pressure air to the second flow path 32, and a high-pressure air that is provided in the second flow path 32 and expanded to expand the high-pressure air to the first flow path at high speed. A throttle orifice 32b for ejecting into the flow path 31 is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction motor capable of obtaining a high output without increasing the size.

[0002]

2. Description of the Related Art FIG. 7 shows, for example, "illustrated induction motor" issued by Tokyo Denki University Press (issued on November 30, 1979, the first printing).
FIG. 7 is a cross-sectional view showing the configurations of a conventional induction motor and a blower described on page 3 of FIG. In the figure, 1 is the rotor shaft, 2
Is a rotor core attached to the rotor shaft 1, 3 is a rotor conductor incorporated in the rotor core 2, 4 is a tubular frame, and one end plate 4a supports one end of the shaft 1 at one end.
However, the other end has an end plate 4b that supports the other end of the shaft 1.
Is provided, and the end plate 4b is provided with a wind vent hole 4c. 5a and 5b are end plates 4a and 4
b, which is arranged between the shaft 1 and the shaft 1, and which supports the rotor shaft 1, 6 is a stator core that is mounted on the frame 4 at a distance from the rotor core 2, and 7 is insulated from the stator core 6. A built-in stator coil, 8 is a blower tube connected to the frame 6 with an opening at one end side, 9 is an electric motor attached to the end of the blower tube 8, and 10 is a blower driven by the electric motor 9. , 11 are cooling air flow paths formed in the gap between the rotor core 2 and the stator core 6.

Next, the operation will be described. When the induction motor is driven, the electric motor 9 that rotates the blower 10 is also driven, and the cooling air (cooling air) generated by the blower 10 is
As shown by the arrow in the figure, the air is sent from the blower tube 8 into the frame 4, and one end of each of the rotor conductor 3 and the stator coil 7 is cooled to form in the gap between the rotor core 2 and the stator core 6. The rotor core 2 and the stator core 6 are cooled as they pass through the flow path 11. Then, the other ends of the rotor conductor 3 and the stator coil 7 are cooled and discharged to the outside through the air vent hole 4b of the end plate. When an alternating voltage is applied to the stator coil 7, an alternating current flows in the stator coil 7,
Induction current corresponding to the magnetic flux generated in the stator flows through the rotor conductor 3, causing copper loss. Furthermore, rotor core 2
And a loss called iron loss is also generated in the stator core 6, and all of these losses become heat, which causes a temperature rise of the induction motor. Here, an insulator is used for the stator coil 7, and the maximum temperature rise is regulated by the type of the insulator. For this reason, the design is made so as to be equal to or less than the heat generation amount Q (w) represented by the equation (1) described later. By the way, when the insulation class of the stator coil 7 is type B, the maximum allowable temperature is 130 ° C., and the temperature of the supplied air is 40.
If the temperature is ° C, the insulating material used must be suppressed below the temperature rise of 90K. Here, the heat generation amount is Q (w), the heat dissipation area is S (m ² ), and the heat transfer coefficient is α.
(W / m ² K) and the temperature rise is Δθ (K), the relationship of the equation (1) is established. Q = α · S · Δθ (1) If the insulation class is B type, Δθ is 90K or less.

Usually, the induction motor has a large capacity (high output).
On the other hand, since the calorific value Q increases with the capacity, the temperature rise Δθ has been allowed to rise to a high temperature. Also,
The temperature rise Δθ is expressed as an average temperature, but the temperature distribution of the induction motor is such that the average temperature shown by A in the curve diagram of FIG. The upper side (supply side) has a relatively low temperature, and the leeward side (exhaust side) tends to have a higher temperature due to overheating of the cooling air. If the temperature difference is large, the average temperature Δθ is less than the constraint. It may be restricted by the temperature increase on the leeward side.

[0005]

Since the conventional induction motor is constructed as described above, the output of the induction motor is
This is determined by the allowable temperature of the insulating material used and the heat transfer coefficient by the cooling air, and there is a problem that a large induction motor must be used to obtain high output.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain an induction motor capable of obtaining high output without increasing the size.

[0007]

The induction motor according to the present invention has 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. A second flow path communicating with the first flow path, a high pressure air supply device for supplying high pressure air to the second flow path, and a high pressure air provided in the second flow path for expansion. It is provided with a throttle orifice for ejecting into the first flow path at high speed.

[0008]

The throttle orifice provided in the second flow passage of the induction motor according to the present invention expands high-pressure air and jets it into the first flow passage at high speed.

[0009]

EXAMPLES Example 1. Embodiment 1 of the present invention will be described below with reference to the drawings. 1 is a sectional view showing the structure of an induction motor according to Embodiment 1 of the present invention. In the figure, 21 is a rotor shaft, 22 is a rotor core attached to the rotor shaft 21, and 23 is a rotor core.
Is a rotor conductor that is short-circuited and installed in the rotor core 22, 24
Is a cylindrical frame, one end of which is provided with an end plate 24a that supports one end of the shaft 1, and the other end of which is provided with an end plate 24b that supports the other end of the shaft 21, and this end plate 24b has a wind vent hole 24c. It is provided. 25a and 25b are bearings arranged between the end plates 24a and 24b and the shaft 21;
Is a stator core attached to the frame 24 at a distance from the rotor core 22, 27 is a stator coil insulated and incorporated in the stator core 26, and 28 is an opening provided at one end of the frame 24. The connected blower tube, 29 is an electric motor attached to the end of the blower tube 28, and 30 is a blower driven by the electric motor 29. A flow path 31 for cooling air is formed in a gap formed by the rotor core 22 and the stator core 26. 32 is the stator core
As shown in the cross section in FIG. 3, a high pressure air transporting portion 32a, which is an air pipe that is disposed so as to penetrate through 26 and the frame 24 and forms a second flow path, and a high pressure air transporting portion.
A throttle orifice portion 32b for narrowing the high-pressure air sent from 32a to a diameter smaller than that of the high-pressure air transport portion 32a, and an expansion cylinder 32c connected to the flow path 31 for expanding the high-pressure air sent from the throttle orifice 32b are provided. .. 33 is a solenoid valve connected to the high-pressure air transport unit 32a, 34 is a high-pressure air storage tank, 34a is an air pipe connecting the high-pressure air storage tank 34 and the solenoid valve 33, 35 is an air compressor, 35a is an air compressor An air pipe connecting 35 to the high-pressure air storage tank 34, a controller 36 for controlling the solenoid valve 33, and a control signal line 36a connecting the controller 36 and the solenoid valve 33. In the above 33 to 36, the high pressure air supply device 37
Is formed.

FIG. 2 is a sectional view of an induction motor according to a first embodiment of the present invention, in which a plurality of second flow passages (air pipes) 32 are provided in a rotor shaft 21 in a circumferential direction of a stator core 24. Toward the second flow path, a predetermined number of stator coils 26 are arranged between the stator coils 26.
32 are each connected to a solenoid valve 33, and further each solenoid valve 33 is connected to a high pressure air storage tank 34 by connecting a common air pipe 34, and this high pressure air storage tank 34 is compressed by an air pipe 35a. Connected to machine 35. Each solenoid valve 33 is connected to the controller 36 by a control signal line 36b so that each solenoid valve 33 can be controlled simultaneously.

Next, the operation will be described. When the induction motor is operated, the blower 30 is also operated at the same time, and the air taken in by the blower 30 is used as cooling air and the internal flow path 31 of the induction motor is used.
To heat the rotors 22 and 23 and the stators 26 and 27 that generate heat, and are discharged to the outside through the air vent holes 24c of the end plate 24b. On the other hand, with the solenoid valve 33 closed in advance, the air compressor 35 is driven to drive the high pressure air storage tank 34.
Is filled with high pressure air, and the high pressure air storage tank 34 is maintained at a high pressure state (pressure P1). When the induction motor is operated, each solenoid valve 33 is opened by a control signal from the controller 36, and high pressure air flows from each high pressure air transport pipe 34 to each solenoid valve.
It is supplied to each air pipe 32 through 33. When this high-pressure air passes through each throttle orifice 32b, the flow velocity is increased and the expansion cylinder 32 expands to lower the pressure, and the expanded volume causes the temperature to drop, thereby directly cooling the stator core 26. The second cooling air is sent to the flow path 31.

Here, when the high-pressure air passes through the throttle orifice 32b, the enthalpy decreases as the velocity energy increases. However, in practice, this decrease in enthalpy is often small and neglected. In air, a temperature drop occurs due to the throttle as shown in equation (2). Δt = a (P1−P2) (273 / T1) ² (2) where Δt: temperature drop (K) a: constant (a = 0.272: air) P1, P2: pressure ( Kgf / cm ² ) T1: Temperature (K) In FIG. 1, throttle orifice 32b and expansion cylinder 32c.
Is operated, there is a temperature drop Δt (K) according to the equation (2), so the heat quantity Q ¹ that can be processed is Q ¹ = α · S · [θW- (θair-Δt)] = α · S · [( θW−θair) + a ・ (P1−P2) (273 / T1) ² ] = α ・ S ・ [Δθ + a ・ (P1−P2) (273 / T1) ² ] = α ・ S ・ Δθ + α ・ S ・ a (P1 −P2) (273 / T1) ² = Q + α · S · a (P1−P2) (273 / T1) ² (3) However, Δθ = θW−θair Q: Conventional heat capacity (W) θW: Heat transfer surface temperature (K) α: Heat transfer coefficient (W / m ² ) θair: Air temperature (K) S: Electric heating area (m ²⁾ The heat quantity to be processed is increased by using the throttle orifice 32b and the expansion cylinder 32c as shown in the above equation (3). The temperature distribution of the induction motor according to the first embodiment is shown in FIG.
The distribution curve becomes as shown by C in the curve diagram, and the average temperature also decreases as shown by D in the curve diagram.

Embodiment 2. FIG. 5 is a side view showing a cross section of a configuration of an induction motor according to a second embodiment of the present invention. In the figure, 21 to 37 are the same as those in the first embodiment (FIG. 1), and thus the description thereof is omitted. 38 is an air pipe forming the second flow path. As shown in cross section in FIG. 6, the air pipe 38 is provided with a high-pressure air transport section 38a and a throttle orifice 38b reduced in diameter to be smaller than the high-pressure air transport section 38a. The air pipe (second flow path) 38 penetrates the outer periphery of the frame 24 on the leeward side and is arranged so that the other end of the stator coil 27 and the throttle orifice 38b face each other and expand the high pressure air. It is jetted toward the stator coil 27 which has a high speed and a high temperature. Such an induction motor of FIG. 5 obtains the temperature distribution of the curve E of FIG.

Example 3. The above-mentioned first and second embodiments are
In each of the cases, the case where the cooling air is generated by the blower 30 has been described, but the fan may be provided with a fan (not shown) that takes in outside air by the rotation of the rotor shaft 21.

[0015]

As described above, according to the present invention, there is provided the first flow path for passing the cooling air introduced from one end of the frame between the stator and the rotor and discharging the cooling air from the other end of the frame. , A second flow path communicating with the first flow path, a high-pressure air supply device for supplying high pressure air to the second flow path, and an air provided in the second flow path for expanding the air to be sent to the second flow path at high speed. Since the configuration is provided with the throttle orifice for ejecting into the first flow path,
It is possible to provide an induction motor that can obtain high output without increasing the size.

[Brief description of drawings]

FIG. 1 is a side view showing a cross section of a configuration of an induction motor according to a first embodiment of the present invention.

FIG. 2 is a front view showing a cross section of the configuration of the induction motor according to the first embodiment of the present invention.

FIG. 3 is a sectional view showing a throttle orifice in FIG.

FIG. 4 is a curve diagram showing temperature distributions of the present invention and the conventional induction motor.

FIG. 5 is a side view showing in section a structure of an induction motor according to a second embodiment of the present invention.

6 is a cross-sectional view showing a throttle orifice in FIG.

FIG. 7 is a side view showing a cross section of a conventional induction motor.

[Explanation of symbols]

 22 rotor 24 frame 26 stator 31 first flow path 32 second flow path (air tube) 32b throttle orifice 37 high pressure air supply device

Claims (2)

[Claims] 1. A first flow passage communicating cooling air introduced from one end of a frame between a stator and a rotor and discharging from the other end of the frame, and communicates with the first flow passage. A second flow path, a high pressure air supply device for supplying high pressure air to the second flow path, and a high pressure air provided in the second flow path for expanding the high pressure air to the first flow path at high speed An induction motor having a throttle orifice for jetting. 2. The induction motor according to claim 1, wherein the second flow passage penetrates the stator toward the axial center.