JPH01268486A - Variable speed induction motor - Google Patents

Abstract

PURPOSE:To smoothly rotate a stator formed to be rotatable with a small force by forming the contact part of a frame with a ball bearing of ductile cast iron or steel iron, and surface hardening the contact part. CONSTITUTION:Stators 12A, 12B are aligned in parallel on the inner wall face of a frame 10 oppositely to the outer peripheral surfaces of rotor cores 2A, 2B. The stator 12B is secured to the inner wall face of a frame 10, and the stator 12A is rotated relatively to the secured stator 12B by a rotating mechanism composing a small-sized motor 15 and gears 16, 17 as main components. The motor 15 is rotated at an arbitrary amount to generate a phase difference between rotor conductors corresponding to the stators. The contact part of the frame with a ball bearing 85 is formed of ductile cast iron or steel iron, and surface hardened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a variable speed induction motor2), and more specifically, a single rotor, a plurality of stators, and a plurality of fixed A voltage that causes a phase difference between the voltage induced in a rotor conductor portion facing one stator and the voltage induced in a corresponding rotor conductor portion facing the other stator. The present invention relates to a variable speed induction motor with a so-called multiple stator configuration, which has a phase shift device and can arbitrarily change the rotational speed of a rotor and the generated torque by adjusting the voltage phase shift device.

[Conventional technology]

Methods of controlling the speed of an induction motor include changing the power supply frequency, changing the number of poles of the winding on the stator, and controlling the secondary voltage2).
As described in the publication, the stator is divided into two sets, a fixed stator and a movable stator, each with the same winding and connected to the same power supply, and the rotor is also divided into two sets and the rotor conductors are connected to the same power source. are connected at the center with a wide barbed conductor and at both ends with a short-circuit ring, so that the movable stator is rotated and the secondary induced voltage induced by the other fixed stator is Same-
A variable speed induction motor is a variable speed induction motor that generates different phase currents in the conductor so that the current of the sum of two vectors passes through the rotor conductor as a secondary current, and the speed of the motor can be arbitrarily varied. Since the child is attached to a sliding bearing and is formed to move, the dynamic friction between the moving stator and the sliding bearing is large, and when the moving stator is rotated to control the speed of the rotor, It requires a large amount of force, and even if the movable stator is automatically controlled by a small motor, the capacity is large, resulting in a considerable load, so the use of a large rotating motor is unavoidable2), and the large amount of wasted power is dissipated. Not only that, but it is practically impractical. This tendency became more pronounced as the variable speed induction motor became larger.

[Problem to be solved by the invention]

In the present invention, by having a resistive material that short-circuits the rotor conductors, 2) the phase difference caused by the voltage phase shift device causes a current to flow through the resistive material and increase the rotor resistance. Although it is possible to generate a large torque, the reaction force exerted on the stator is also large. Although it was possible to generate a large amount of torque, the resistance material generated a large amount of heat, which caused the rotatable stator to be engraved. However, the present invention is intended to provide a technique to solve this problem.

[Means to solve the problem]

In order to achieve the above object, the present invention has a plurality of rotor conductors installed in a continuous manner on a plurality of rotor cores that are mounted on the same rotation shaft at regular intervals, and The child conductor has an integral rotor short-circuited by a resistive material between the plurality of rotor cores, and each stator core facing each rotor core of the rotor, and has a stator core that is connected to the rotor. A plurality of stators are provided circumferentially on a circumferential shaft, and a ball bearing or a roller bearing is fitted to the outer periphery of at least one stator among the plurality of stators, and the stator is mounted on the machine frame. A rotating stator is formed so as to be rotatable concentrically with the rotor, and a contact portion of the machine frame with the ball bearing or roller bearing is formed of ductile cast iron or steel. The solution was to perform surface hardening treatment. In addition, a special feature of the present invention solves the problem by performing induction hardening for the surface hardening treatment of the contact portion.

The variable speed induction motor of the present invention can be formed into either a single-phase or three-phase type, and the rotor can have a rotor shape such as a normal squirrel cage type, a double squirrel cage type, a deep groove cage type, a special squirrel cage type, and a single winding type. The conductor used in the description of the present invention refers to a conductor installed in a squirrel cage rotor core and a wire wound around a wire-wound rotor core. It is a general term for.

[For production]

The operation of the variable speed induction motor configured as described above is as follows. In other words, by fitting ball bearings or roller bearings around the outer periphery of the stator and attaching it to the machine frame, by adopting a rolling bearing system, 2)
), it has become possible to rotate the stator with a small force (2), and it has become possible to reduce the size of the rotation drive device and the like.

In this variable speed induction motor, the torque of the rotor is large due to the action of the resistive material, and the stator receives a reaction force, so a large force is required to rotate the stator while driving a load. The bearing system allows for easy rotation.

In addition, this variable speed induction motor uses the action of the resistive material 2).
Although it can produce large torque, it also generates a large amount of heat.
The rotatable stator is engraved and a large force is applied to the ball bearing or roller bearing2), and a large force is also applied to the machine frame, so if the engraving is large, the ball bearing or roller bearing is 2) The contact points of the ball bearing or roller bearing with the stator or the machine frame are worn out due to vibrations during motor operation.
In the present invention, the above-mentioned problems have been solved since a configuration has been added that significantly improves the wear resistance.

In other words, in this electric motor, when the phase difference is increased to produce a large torque, heat generation is relatively concentrated in the resistive material, but the rolling bearing device with the above configuration has greatly improved wear resistance and strength. be.

〔Example〕

As explained below, the present invention is normally used as a variable speed induction motor, but its startability is limited to using a phase difference of 180" or larger during startup and Oo or smaller during operation. It can also be used as an improved induction motor.

In addition, in order to make the air flow more effective through the blades provided between the rotor cores, ventilation holes may be provided in the rotor cores that communicate from the open side of the rotor core to the other end 2). In the case where the rotating shaft is hollow and ventilation holes communicating from the inner circumference to the outer circumference are provided between the rotor cores to allow air to flow into the ventilation shell, ventilation holes may be provided on the outer circumference of the fixed stator to allow the air to flow in. It may also make it more effective.

These vents are perfect! Even when ventilating with a 1m air blower, the effect of ventilation is further enhanced.

Examples will be described below with reference to the drawings.

First, the configuration of a variable speed induction motor to which a cooling device according to the present invention is applied will be schematically explained. Rotor cores 2A and 28 are mounted on the rotor shaft 3 of the rotor 2 with a constant interval therebetween. A non-magnetic core portion 2C is provided between the rotor cores 2A and 2B. On the rotor cores 2A, 2B, a plurality of rotor conductors 4 are connected in communication between the outer ends of the rotor cores 2A, 2B.
- is installed in a cage shape, and both ends thereof are mutually short-circuited by short-circuit rings 5 and 6. The rotor conductors 4 are connected to each other by a resistive material R at the non-magnetic core portion 2C (resistance short-circuited). The rotor 2 configured in one direction in this way
is rotatable within the motor frame 10 by having its both ends pivotally supported by bearings 7, 7.

Stators 12A and 12B are arranged in parallel on the inner wall surface of the machine frame 10, facing each outer peripheral surface of the rotor cores 2A and 2B. In the illustrated embodiment, the stator 12B is a fixed stator fixed to the inner wall surface of the machine frame 10, but the stator 12A is equipped with a small motor 15 and gears 16 and 17 (gear 17 is the stator core It is possible to rotate relative to the fixing stator 12B by means of a rotation mechanism whose main component is (2) which is fitted onto the outer circumferential surface. 92 is a ventilation hole provided on the outer periphery of the rotary stator. 85 is a ball bearing. By operating this rotation mechanism 2), specifically by rotating the small motor 15 an arbitrary number of times 2), a phase difference is created between the rotor conductor portions corresponding to each stator of the rotor. . That is, in the illustrated embodiment, this rotation mechanism constitutes the voltage phase shifter 18. Note that the stator windings 13A, 13B wound around the stators 12A, 12B may be connected to the power source either in series or in parallel. Further, in the illustrated embodiment, a rotating mechanism is used as the voltage phase shifter, but it may also be configured by purely electrical means such as a stator winding connection switching method or an induced voltage type phase shifter. It may also be a combination of a rotation mechanism and electrical means.

Next, the specific configuration of the cooling device 40 will be explained.

The cooling device 40 includes a blower device 50 and a control device 60. The blower device 50 has an open top-shaped air outlet 1ji51, which is fixed to surround an air exhaust port 20 opened at a proper position of the electric motor frame 10 (in the case of the illustrated embodiment, the central upper position).
It is composed of a fan motor 52 supported by the lJIi 51 and a fan 54 that is pivotally attached to the rotating shaft of the motor 52. The control output of the control device 60 is connected to the fan motor 52 of the sending device 50, and on its input side, as a control information source, a speed detector 70, such as a tachogenerator, for detecting the rotational speed of the rotor 2, a voltage phase shifter, etc. A phase shift detector 80 (see FIG. 2) that detects the phase difference set by the device 18, and specific parts in the induction motor frame 10 where heat tends to accumulate or the surrounding space of such parts. A temperature detector 90, such as a thermistor, is connected to the temperature sensor 90, which is disposed at an appropriate location in the part and detects the temperature of the part or space. Note that the speed detector 70 is not limited to a tachometer generator, and may be a non-contact tachometer such as a strobe type tachometer or a photoelectric tachometer. It can also be arranged and used in connection with...etc.

FIG. 2 shows an example of a phase detector 8o connected to the control device 60. The phase detector 80 includes a magnetic sensor 82 mounted on the outer peripheral surface of the rotating stator 12A to detect magnetism, and a non-magnetic plate 8 mounted on the inner peripheral surface of the machine frame 10.
3, and is composed of a plurality of magnetic generating bodies 84 (only 84b to 84' are shown in the drawing) which generate different magnetic forces due to different diameters.

The control device 60 constantly receives various information that changes during the operation of the electric motor from each of the detectors 70, 80, 90, and controls the operation of the blower device 5o as follows based on the information.

The input information from the rotation detector 70 indicates high speed operation, the input information from the phase detector 80 indicates that the phase difference is small, and the input information from the temperature detector 9o indicates that the temperature is low. If so, the control device 60 determines that the condition inside the machine frame 1o does not require much forced cooling and heat dissipation, and controls the fan motor 52 of the blower device 50 to shut down or decelerate the fan motor 52. Outputs a signal to perform power-saving operation.

On the contrary, one of the three input information described above is the opposite information, that is, the information that either the low speed operation 2 phase difference is large or the temperature is high is input to the control device 60. In this case, the control device 60 determines that the condition inside the machine frame 10 is such that forced cooling heat dissipation is required, and controls the fan motor 52 of the blower device 50 to start operation or accelerate the operation. A control signal is output to prevent quality deterioration and further thermal destruction of the parts that make up the motor due to heat. In addition, if the operation of the induction motor itself is stopped under such conditions, a timer function provided in the control device 60 is activated as necessary, and the operation of the blower device 50 is maintained at a constant level even after the motor is stopped. Not only can the electric motor be completely protected from thermal damage over a long period of time, but also the smooth rotation of the rotary stator 12A is completely ensured.

Note that the object of the present invention can also be achieved by forming the air blower 86 into an impeller to improve the cooling performance without using the blower 50. In this case, as shown in Fig. 3, a hollow part 87 is provided in the rotating shaft 88, and a ventilation hole 89 is provided between the rotor cores, and the inner peripheral part is communicated with the outer peripheral part to allow air to flow in, thereby improving cooling performance. 2), as shown in 91, ventilation holes may be provided in the rotor core to allow air to flow in to improve cooling performance 2), and ventilation holes may be provided on the outside of the fixed stator. In some cases, the cooling performance is improved by providing air inflow.

When rotating the rotary stator within the machine frame in the variable speed induction motor of this configuration, it is necessary to use a rolling bearing, but if a general rolling bearing were used, it would be extremely expensive. By the way, in the variable speed induction motor of this configuration, the rotation speed of the rolling bearing section is usually extremely small;
In addition, focusing on the fact that the load is relatively small, the contact part of the machine frame with the ball bearing or roller bearing was made of ductile cast iron or steel, and the contact part was subjected to surface hardening treatment to achieve this goal. That's what I did.

In some cases, the machine frame is made of ordinary cast iron and a ring made of another material, ductile cast iron or steel, is inserted into the inner circumference of the machine frame and subjected to surface hardening treatment. In some cases, surface hardening treatment is applied to the contact area.

- In a variable speed induction motor like this configuration, the machine frame is made of ordinary cast iron, but the surface is highly hardened and the contact parts with ball bearings or roller bearings wear out quickly. Otherwise, the motor will vibrate and become unusable.

On the other hand, since ductile cast iron or steel has excellent surface hardening properties, it is possible to form the machine frame with ductile cast iron and apply surface hardening treatment to the contact areas, or to form the machine frame with general cast iron and use ductile cast iron or steel. The ring was fitted into the inner periphery of the machine frame, and the surface was hardened.

For example, when using ductile cast iron, it is annealed at around 500°C to relieve stress, then the inner peripheral surface is finished by machining, then induction hardened on the inner peripheral surface, and then at a low temperature of around 200°C to relieve stress. Examples include tempering and final machining and polishing.

In addition to induction hardening, surface hardening treatments include flame hardening, carburizing hardening, ion nitriding, thermal spray coating, plating, and solid lubricant coating. Application of induction hardening in the present invention allows for easy local hardening;
It is particularly advantageous in that the hardened layer can be made deep and it is inexpensive.

Furthermore, the variable speed induction motor of the present invention can also be used as an induction 4 generator (2), and if a turbine or the like is directly connected to the rotor shaft to generate electricity, an expensive governor can be omitted. . In addition, when an internal combustion engine is connected as a prime mover, it can correspond to the rotation speed of the internal combustion engine for minimum fuel consumption, and the power generated from feng shui as an energy source is weak and unstable.
Even in such cases, power can be generated at the rotational speed that produces the maximum output, and in hydroelectric power generation, power can be generated efficiently according to the flow velocity, and complicated and expensive variable pitch devices or phase adjusters can be omitted. Furthermore, synchronization with external power can be performed without an expensive synchronization device. Furthermore, if a switch is provided to connect the rotor shaft to another rotary shaft and to switch the two phases on the input side of the stator winding, and the switch is configured to freely rotate the rotor shaft in the forward and reverse directions through the switch 7, It can also be used as an electric brake by operating a switch and a voltage phase shifter, and by controlling the rotation speed with the voltage phase shifter 2)
, the braking force of the rotating shaft connected to the rotor shaft can be efficiently adjusted.

Furthermore, the invention of the present application is not limited to a variable speed induction motor.
The present invention can also be applied to an induction motor with improved startability, in which the phase difference is set to 180° or larger during startup and 0° or smaller during operation.

In this case, it is possible to suppress the starting current and increase the starting torque.

〔Effect of the invention〕

Since the present invention is constructed as described above, the stator can be rotated with a small force, and even if the stator is operated for a long time or at high torque and generates a large amount of heat, the stator does not rotate at all. This made it possible to smoothly operate a variable speed induction motor with excellent torque characteristics and efficiency without any problems.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a variable speed induction motor equipped with a cooling device according to the present invention, FIG. 2 is a sectional view showing an embodiment of a phase detector, and FIG. 3 is a perspective view of a rotor. In the figure, 2... Rotor, 2A, 2B... Rotor core, 2C... Non-magnetic core portion, 3... Rotor shaft,
4... Rotor conductor, 5.6... Short circuit ring, 7... Bearing, 10... Machine frame, 12A... Rotating stator, 12B
...Fixed stator, 13A, 13B...Stator winding,
15...Small motor, 16.17...Gear, 18.
...Voltage phase shift device, 20... Air exhaust port, 40... Cooling device, 50... Air blower, 51... Air blower body, 52...
...Fan motor, 54...Fan, 60...Control device, 70...Roughness detector, 80...Phase shift detector,
82... Magnetic sensor, 83... Non-magnetic plate, 84
(84b-84g)...Magnetic generator, 85...Ball bearing. 86... Impeller, 87... Hollow part, 88... Rotating shaft, 89... Ventilation hole, 90... Temperature detector, 91...
-Vent hole, 92...Vent hole.

Claims (2)

[Claims] (1) A plurality of rotor conductors are installed in a continuous manner on a plurality of rotor cores that are mounted on the same rotating shaft at regular intervals, and the rotor conductors are connected to the plurality of rotor cores. It has an integral rotor that is short-circuited between the rotor cores by a resistive material, and each stator core that faces each rotor core of the rotor, and has a circumferential portion on a circumferential axis with the rotor. A plurality of stators are provided, a ball bearing or a roller bearing is fitted to the outer periphery of at least one stator among the plurality of stators, and the ball bearing or roller bearing is fitted to the machine frame, and the rotor is concentric with the rotor. The machine frame is shaped to be freely rotatable to form a rotating stator, and the contact portion of the machine frame with the ball bearing or roller bearing is formed of ductile cast iron or steel, and the contact portion is subjected to surface hardening treatment. A variable speed induction motor characterized by: (2) The variable speed induction motor according to claim (1), wherein the surface hardening treatment is induction hardening.