JPS626410B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to electrical machines, and more particularly to electrical machines equipped with cryogenic cooling devices.

The invention has application to electrical machines such as motors, generators, and dynamometers used in transportation and aviation, as well as atomic, steam, and other types of power plants. It is known that the present invention is extremely effective when applied to power units of space planes and other various devices that require cooling of rotating windings to bring them into a superconducting state.

Typically, cryocooled electrical machines include a superconducting field winding mounted within a hollow rotor or rotating cryostat.

The superconducting state of the field winding is maintained by cooling the winding to a very low temperature of about 4.5°. The above is accomplished with the aid of a coolant, usually liquid helium.

As the temperature of the superconducting winding, ie the temperature of the superconductor, decreases, the current increases and the permissible magnetic field strength of the superconducting winding increases, thus increasing the efficiency of the electrical machine. If the temperature of the superconducting winding increases by 1 to 3 degrees, the efficiency of the machine decreases considerably.

BACKGROUND OF THE INVENTION Various types of superconducting electrical machines are known in the art in which the superconducting state of a rotating field winding is maintained by immersing the field winding in liquid helium.

One known cryogenically cooled electric machine includes a superconducting field winding connected to a busbar. A superconducting field winding is placed in the cavity of the rotor and the cavity is filled with a coolant. The windings are mounted on a rotor shaft, one end of which is provided with an axial groove for supplying coolant to the superconducting field windings. Both ends of the rotor shaft are provided with separate grooves for coolant discharge.

Since it is located in a rotating cavity, liquid helium is affected by centrifugal force. This increases the temperature and pressure of the liquid helium, forming a two-phase mixture of coolant and increasing the vapor content in the mixture. In this case, the higher the circumferential speed of the rotor and the larger its radius, the higher the temperature and pressure of the liquid helium. The increase in the temperature of the liquid helium, and therefore the temperature of the rotating superconducting field winding, means that currently manufactured superconducting devices and superconducting windings only function satisfactorily at temperatures below 5 This is not desirable because it causes

The temperature of the superconducting winding is determined by the heat conduction at the contact between the winding and the shaft, which is also disadvantageous for the machine in this paper. When the compressive stress increases due to the compressive force exerted by the superconducting field winding on the shaft, the liquid helium is compressed, and this compression increases the temperature of the liquid helium and therefore the temperature of the superconducting field winding. . The compressive force is essential for transmitting torque from the superconducting winding to the drive. In the method of cooling the superconducting winding by attaching it to a predetermined position, it is difficult to maintain a uniform temperature range in both the surface direction and the radial direction. If the internal cavity of the rotor is completely filled with liquid helium, it is difficult to remove the helium gas phase from the cavity. Also, heat loss and temperature rise of the coolant occurs. The above is caused by friction and compression between two helium phases in the centrifugal force region.

The object of the invention is to provide an electric machine with a low-temperature cooling device in which the thermal protection of the superconducting field winding is very effective and therefore highly efficient.

The object of the above is to provide an electric machine with a low temperature cooling device, in which a superconducting field winding connected to a busbar is placed in a rotor cavity filled with coolant, and the winding is mounted directly on the shaft of the rotor. , an axial channel is provided at one end of the shaft for supplying coolant to the superconducting field winding, and channels for discharging coolant are provided at both ends of the shaft, so that the superconducting field winding is connected to the superconducting field winding over its entire length. A chamber is provided parallel to the axis at the point of attachment to the shaft of the rotor, said chamber communicating with a coolant supply channel and a radial channel provided in the superconducting field winding, and said chamber being connected to the shaft. a vapor phase coolant discharge channel provided along the axis of the rotor shaft at the other end, and a rotor cavity provided on the outer surface of the superconducting field winding over its entire length; This is accomplished by an electric machine with a cryocooler, characterized in that it is in communication with a longitudinal channel for discharging vapor phase coolant from the cryocooler.

The objects and advantages of the present invention will be more readily understood from the following detailed description of the preferred embodiments taken in conjunction with the accompanying drawings.

According to the invention, an electric machine with a cryogenic cooling device comprises a hollow rotor 1 (FIG. 1), the shaft 2 of which is supported by bearing devices 3 installed on both end walls 4 of a sealed frame 5. carried. A stator winding 6 is provided on the inner surface of the frame 5 (detailed explanation of the stator winding 6 will be omitted).

The space between the rotor 1 and the sealed frame 5 is maintained in a vacuum state to thermally insulate the rotor 1. Vacuum is maintained by a rotary vacuum seal 7 located within the end wall 4. The hollow rotor 1 is the shaft 2 of the rotor 1
It has a superconducting field winding mounted above and arranged in a shell 9, said shell 9 forming a cavity in the rotor 1 which is filled with a coolant 10. The field winding 8 is made of a material capable of becoming a superconducting device at very low temperatures, for example a niobium titanium wire fixed in a matrix of pure copper. The field winding 8 is cooled to a superconducting state using a coolant 10 which is liquid helium at a temperature of 4.2㎓.

The field winding 8 is provided with radial channels 11 for cooling. The number of channels is limited only by the structural strength of the superconducting field windings. The superconducting field winding 8 is fixed to the shaft 2 by a known method, for example, by a ferrule made of a thin glass piece (the fixation of the winding 8 is shown in the figure for convenience). Field winding 8 is connected to rotor 1
A chamber 12 is provided on the shaft 2 at the point where it is attached to the shaft 2, parallel to the axis of the rotor 1 and extending over the entire length of the field winding 8. The chamber 12 is covered with an arcuate member 13 made of a thermally conductive material such as bronze. The arcuate member 13 has an opening aligned with the channel 11 of the superconducting field winding 8 .

Both ends of the shaft 2 of the rotor 1 are formed by threaded coaxial tubes 14 and 15, and the gap between the two tubes serves as a channel 16 for discharging the coolant 10. Said channel 16 communicates with the cavity of the rotor 1.

In order to supply the field winding 8 with a coolant 10, the shaft 2 of the rotor 1 is provided with an axial channel 17, which is formed in the form of a vacuum-tight tube extending towards one end of the shaft 2. . A channel 18 for discharging the coolant 10 extends along the axis of the shaft 2 of the rotor 1 towards the other end opposite to the above. Channel 18 as well as channel 17
It is also made of vacuum-tight tubing.

The coolant 10 supply channel 17 and the coolant discharge channel 18 communicate in the chamber 12 . The coolant 10 that has passed through the channels 16 and 18 is introduced into a gas collector 19 located at the end of the shaft 2. The field winding is energized by a copper busbar. The bus bar 20 is provided in the channel 18 for discharging the coolant 10 and is connected to a current collecting ring 21 provided on the shaft 2 on the side of the channel 18 for discharging the coolant 10 .

As shown in FIG. 2, the field winding 8 is a bipolar winding consisting of two sections. The number of chambers 12 is equal to the number of sections. In the case of the present invention, there are two chambers 12.

A chamber 12 is provided under each section of the winding in field windings 8 having different numbers of poles. The width and depth of chamber 12 are determined by the strength characteristics of shaft 2.

Between the poles of the field winding 8 is an insert 22 (FIG. 2) made of an electrically and thermally insulating material, for example mica.
intervenes.

The field winding 8 (FIG. 1) is provided with a radial channel 11 and a longitudinal channel 23 in the interpole insert 22 (FIG. 2).
3 is between the shell 9 and the field winding 8 and the channel 23
communicates through a radial opening extending the entire length of the radial opening.

The coolant 10 discharge channel 18 (FIG. 1) consists of two coaxial core tubes 24 and 25 (FIG. 3). Each busbar 20 consists of two copper conductors of different polarity contained within an inner tube 24. Tube 24 is disposed within tube 25 and supported by an arcuate support member 26 made of electrically and thermally insulating material. An outer tube 25 is arranged in the axial bore of the shaft 2 and is made of an electrically and thermally insulating material, e.g.
It is supported by a spherical support member 27 made of Al ₂ O ₃ .

In FIGS. 1 to 3, the circulation path of the coolant 10 is indicated by arrows.

The field winding 8 (FIG. 1) of the electric machine with low temperature cooling device according to the present invention is cooled in the following manner.

Liquid helium, a coolant 10 (FIG. 1), is pumped under pressure into the cavity of the rotor 1 through a channel 17 from a refrigeration machine (not shown). first coolant 10
reaches the chamber 12 of the shaft 2, where centrifugal force drives the liquid phase of the coolant towards the inner surface of the arcuate member 13. On the other hand, the gas phase generated by compression and friction due to centrifugal force is driven in the axial direction of the shaft. Driven by centrifugal force and pressure, the liquid phase of the coolant 10 enters the interior space of the rotor 1 through the openings provided in the arcs 13 and further through the channels 11 of the field winding 8 . On the inner surface of the shell 9, the coolant 10 separates again into liquid and gas phases. The liquid phase remains on the inner surface of the shell 9, while the gas phase advances through the radial openings and the longitudinal gas channel 23 (FIG. 2) and is formed by the end surface of the shell 9 and the field winding 8. It reaches the ring-shaped area. The gas phase from this place is shaft 2
at both ends of which are directed into channels 16 for discharging the coolant and collected in a gas collector 19.
The gaseous phase of the coolant 10 in the chamber 12 during the above process enters the coolant discharge channel 18, cools the bus bar 20, and is then sent to the gas collector 19. Gaseous refrigerant is sent from the gas collector 19 to a refrigeration machine (not shown).

The electrical machine of the invention provides effective cooling of the superconducting windings of the rotor, so that the temperature of the windings does not rise above the temperature of the coolant. It should be noted that compression within the groove due to centrifugal force does not significantly affect the temperature.
The winding cooling device according to the invention allows liquid helium to be pressurized and used at low temperatures. Therefore, thermal protection of superconducting windings can be made more efficient,
Increase the efficiency of electrical machines. As a result, it is possible to increase the output of an electrical machine using the invention by 50% compared to a conventional machine of the same dimensions.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of an electric machine equipped with a low-temperature cooling device according to the present invention, and FIG. 2 is a longitudinal sectional view of the rotor of the electric machine equipped with a low-temperature cooling device according to the present invention taken along the line - in FIG. FIG. 3 is a partially enlarged longitudinal sectional view of a coolant discharge channel showing the arrangement of busbars, which is the main part of the electric machine according to the present invention. DESCRIPTION OF SYMBOLS 1... Rotor, 2... Rotor shaft, 8... Superconducting field winding, 10... Coolant, 11... Radial channel, 12... Chamber, 16... Coolant discharge channel, 17... Coolant supply 18...another channel for coolant discharge, 20...bus bar.

Claims (1)

[Claims] 1. An electric machine with a low-temperature cooling device, which has a bus bar 20
A superconducting field winding 8 connected to the rotor 1 is provided in a cavity of the rotor 1 filled with a coolant 10, and the winding is directly attached to the shaft 2 of the rotor 1, with the coolant 10 being supplied to one end of the shaft 2. An axial channel 17 for feeding the superconducting field winding 8 is provided, and channels 16 for discharging the coolant 10 are provided at both ends of the shaft 2, so that the superconducting field winding 8 is connected to the rotor 1 over its entire length. A chamber 12 is provided parallel to the axis at the point where it is attached to the shaft 2, and said chamber 12 communicates with a channel 17 for supplying the coolant 10 and a radial channel 11 provided in the superconducting field winding 8, Also, the above room 1
2 is a channel 18 for discharging the gas phase coolant 10 provided along the axis of the shaft 2 of the rotor 1 at the other end of the shaft 2, and a channel 18 for discharging the gas phase coolant 10 provided along the axis of the shaft 2 of the rotor 1, and a channel 18 for discharging the superconducting field winding 8 over the entire length thereof. An electric machine with a low-temperature cooling device, characterized in that the electric machine is connected to a longitudinal channel 23 provided in the rotor 1 for discharging a vapor phase coolant from the cavity of the rotor 1. 2. Electric machine with cryogenic cooling device according to claim 1, in which the bus bar 20 is provided in an axial channel 18 for the discharge of the vapor phase coolant 10 from the chamber 12.