JPH0257719A - Cooling method and cooling device for electromagnetic bearing - Google Patents

Abstract

PURPOSE:To interrupt heat conduction to an electromagnetic bearing effectively by providing a groove on the external surface of a rotating shaft or the internal surface of an electromagnetic coil fitted closely to the rotating shaft and flowing cooling fluid through the groove. CONSTITUTION:Cooling fluid enters a circular duct 11 provided on the periphery of a bearing casing 1 through a pipe 12. The fluid passes through a through hole 13 and a splined groove 9, cools a rotating shaft 37, and comes out of a ring 51. Though any cooling means is not provided linearly on a thrust bearing section S, the thrust electromagnetic bearing section S is protected from heat since the heat conducted from a blade 33 and a disk 34 is dissipated by means of the cooling fluid flowing through the splined groove 9 before it reaches the thrust electromagnetic bearing sections S. Thus the groove 9 is provided on the rotating shaft 37 on which the cylindrical core 3 of the electromagnetic bearing is closely fitted to allow the cooling fluid to pass through, heat conduction to the electromagnetic bearing S can be effectively interrupted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and a cooling device for cooling an electromagnetic bearing supporting a shaft of a rotating device whose rotating body becomes hot during operation.

In the present invention, high temperature refers to a temperature that is higher than the heat resistance limit temperature of the insulating material of the coil portion of the electromagnetic bearing.

[Conventional technology]

An electromagnetic bearing is a device that energizes a coil wound around a core and uses the electromagnetic attraction force to levitate a rotating body in space and support it rotatably without contact.

The latest technology regarding electromagnetic bearings is known in the Journal of the Japan Society of Mechanical Engineers, Vol. 90, No. 821, p. 122, "Development of Electromagnetic Bearing Type Rotating Equipment."

[Problem to be solved by the invention]

For example, when an electromagnetic bearing is used to support the shaft of a rotating body, such as a rotor of a steam turbine or a gas turbine, which becomes hot during operation, cooling is required to protect the insulating material of the electromagnetic coil from high heat.

An object of the present invention is to provide a cooling method that can effectively block heat transfer to an electromagnetic bearing that supports the shaft of a rotating member that is operated at high temperatures, and a cooling device that can implement the above-described method with a simple configuration. This is what I am trying to do.

[Means to solve the problem]

The basic principle of the present invention, which was created to achieve the above object, is that a groove is provided at the interface between the rotating shaft and the core of the electromagnetic coil fitted to the rotating shaft, and a cooling fluid is provided in the groove. It distributes.

The above-mentioned groove may be provided on the outer circumferential surface of the shaft, or may be provided on the inner circumferential surface of the core.

As a concrete configuration for putting the above principle into practical use, one method of the present invention is to provide a groove on the outer circumferential surface of the shaft or the inner circumferential surface of the core, and to allow a cooling fluid to flow through the groove.

Further, the device of the present invention created to carry out the above-mentioned method of the present invention comprises a groove provided on the outer peripheral surface of the shaft or the inner peripheral surface of the core, and means for supplying a cooling fluid to the groove. .

When the electromagnetic bearing is also equipped with an electromagnetic thrust bearing, the groove is located closer to the high-temperature rotating body than the thrust bearing.
That is, it is desirable to provide it on the upstream side in the direction of heat flow.

[Effect]

In conventional techniques, the cooling of electromagnetic bearings was only concerned with cooling the outside of the electromagnetic bearing with air. According to the configuration of the method of the present invention described above, cooling fluid (which may be air) is directly supplied. Let it flow by touching the shaft.

Thus, heat flow from the high-temperature rotating body to the coil portion of the electromagnetic bearing passes through the rotating shaft.

Therefore, by cooling the shaft midway through the heat transfer path, the electromagnetic bearing can be thermally protected extremely effectively.

Moreover, by providing the grooves, the heat transfer area between the cooling fluid and the metal member is increased, and effective cooling is performed.

Further, the device of the present invention includes a groove on the outer circumference of the shaft or the inner circumference of the core;
Since the apparatus is provided with a means for supplying cooling fluid to the grooves, the method of the present invention for flowing cooling fluid into the grooves can be carried out easily and reliably.

The cylindrical core to which the device of the present invention is applied is a component of the journal electromagnetic bearing, but if this electromagnetic bearing is also equipped with a thrust electromagnetic bearing, the cylindrical core to be cooled by the device of the present invention is When disposed upstream of the thrust electromagnetic bearing in the heat transfer direction, the heat flow is blocked (or significantly reduced) by the cylindrical core, so the thrust electromagnetic bearing is thermally protected.

〔Example〕

FIG. 1(A) is a sectional view of an electromagnetic bearing equipped with an embodiment of a cooling device according to the present invention. Figure CB) is a temperature distribution chart added in correspondence with Figure (A).

This example is an example in which the present invention is applied to a steam turbine,
Rotating body (turbine rotor) temperature during rated operation 40
It is 0°C. In comparison, the heat resistance of the insulating enamel used for the coil of the electromagnetic bearing is 220°C (heat resistance of class 0 insulation).

The bearing casing 1 is fixed to a bearing box 50 and fixedly supports the stationary core 2 of the journal electromagnetic bearing (radial direction bearing).

An electromagnetic coil 4 is wound around the stationary core 2 .

The rotating core 3 has a cylindrical shape, is fitted onto the rotating shaft 37, and is fitted concentrically with the stationary core 2 through a small gap, forming a magnetic flux loop and floatingly supported by magnetic force. has been done.

A spline-shaped groove 9 is cut on the outer periphery of the rotating shaft 37, and the rotating core is externally fitted and fixed to the land portion.

When carrying out the present invention, the spline-shaped groove 9 may be linear or helical, and its tooth profile does not necessarily need to be precise.

The spline-shaped groove 9 is cut in a section corresponding to at least the length L of the cylindrical rotating core 3. In this example, it is further extended to the right in the figure and is cut to reach the outside of the shaft penetrating ring 51.

The illustrated numeral 10 is a sleeve that covers the spline groove 9 of the extension.

The cooling fluid (in this example, ambient temperature atmosphere) is supplied to the pipe 12.
It enters the annular duct 11 provided on the outer periphery of the bearing casing 1, flows through the communication hole 13, flows through the spline groove 9, cools the rotating shaft 37, and is discharged to the outside of the ring 51. be done.

On the other hand, in the high-temperature part of the turbine in this embodiment, the blades 33 installed in the disk 34 are blown with high-temperature, high-pressure steam from the nozzle 32, and are heated and rotated. The nozzle 32 described above is installed on the diaphragm 31. 30 is a chest, and 36 is a labyrinth for sealing steam.

Part 8 in the figure is a thrust electromagnetic bearing part, and the rotating shaft 37
It is composed of a flange-shaped collar 5 fixed near the end of the core 6, a pair of cores 6 and 7, and a coil 8, which face each other with a small gap in between, with the collar 5 in between.

In this example, although no cooling means is provided directly to the thrust bearing portion S, the blade 33. On the way to the thrust electromagnetic bearing part S, the heat conduction from the disk 34 is cooled by the cooling fluid flowing through the spline-shaped groove 9, so the thrust electromagnetic bearing part S is in a thermally protected position and is prevented from overheating. There is no danger.

When carrying out the present invention, it is desirable to arrange the thrust electromagnetic bearing S on the downstream side in the heat flow direction of the rotating side core 3 (cylindrical member fitted to the rotating shaft) of the radial electromagnetic bearing.

In consideration of the unlikely event of a power outage accident, the shaft end of the rotating shaft 37 is supported with respect to the casing 14 by a backup bearing 15. 39.40 is nuts.

In this example, the inside of the bearing box 50 is maintained at a positive pressure by supplying the cooling fluid. Therefore, there is no risk of moisture or dust in the air entering the electromagnetic bearing.

Although not shown, as an embodiment different from the above, the rotating shaft 3
Instead of cutting a groove (for example, a spline-shaped groove 9) on the outer circumference of the core 7, a groove may be provided on the inner circumference of the cylindrical rotating core 3 to allow the cooling fluid to flow through the same effect. can get.

〔Effect of the invention〕

As explained above, in the method of the present invention, a groove is provided in the rotating shaft or the cylindrical core along the fitting surface between the cylindrical core and the rotating shaft of the electromagnetic bearing to allow the cooling fluid to flow. The heat flow that has been conducted is blocked (or significantly weakened) at this part.

Overheating of the insulating coating of the coil wound around the rotating core can be prevented.

Furthermore, since the device of the present invention is provided with a groove along the fitting surface between the rotating shaft and the rotating core, and a means for supplying cooling fluid to the groove, the method of the present invention can be easily carried out. can do.

[Brief explanation of the drawing]

FIG. 1(A) is a cross-sectional view of an electromagnetic bearing equipped with an embodiment of the cooling device according to the present invention, and FIG. 1(B) is a chart showing temperature distribution drawn in correspondence with the above-mentioned cross-sectional view. 1... Bearing casing, 2. Stationary side core of the medium journal electromagnetic bearing, 3... Similarly cylindrical rotating side core, 4...
- Electromagnetic coil, 5... Collar of thrust electromagnetic bearing 6.
7... Core on stationary side, 8... Coil, 9... Spline groove, 11... Duct, 12... Pipe, 32... Turbine nozzle, 33... Turbine blade , 34...turbine disk.

Claims (1)

[Claims] 1. In a method for cooling an electromagnetic bearing that supports the shaft of a rotating member operated at high temperatures, a groove is provided on the surface where the shaft faces the cylindrical core of the electromagnet; A method for cooling an electromagnetic bearing, characterized by flowing a cooling fluid through a groove. 2. In a method for cooling an electromagnetic bearing that supports the shaft of a rotating member that is operated at high temperatures, a groove is provided on the inner peripheral surface of the cylindrical core that is fitted to the shaft, and a cooling fluid is poured into the groove. A cooling method for an electromagnetic bearing, characterized by causing a flow of . 3. In a device for cooling an electromagnetic bearing that supports the shaft of a rotating member operated at high temperatures, a groove provided in the surface where the shaft faces the cylindrical core of the electromagnet of the electromagnetic bearing, and a groove provided in the above groove. A cooling device for an electromagnetic bearing, comprising a means for supplying a cooling fluid. 4. In a device that cools an electromagnetic bearing that supports the shaft of a rotating member that operates at high temperatures, a groove provided on the inner peripheral surface of the cylindrical core of the electromagnet fitted to the shaft, and a cooling 1. A cooling device for an electromagnetic bearing, comprising means for supplying a cooling fluid. 5. The cylindrical core and the groove are provided upstream of the thrust electromagnetic bearing receiving the thrust of the shaft with respect to the direction of heat flow conducted within the shaft. A cooling device for an electromagnetic bearing according to claim 3 or 4.