DK201400181A1

DK201400181A1 - Non-touching rotational contact

Info

Publication number: DK201400181A1
Application number: DK201400181A
Authority: DK
Inventors: Christen Espersen; Klaus Madsen; Lars Mellgaard; Jørgen Marcus Nøhr Clausen
Original assignee: Applied Turbine Technologies Aps
Priority date: 2014-03-31
Filing date: 2014-03-31
Publication date: 2015-10-12

Abstract

The present invention relates a non-touching rotational contact comprising a magnetic element adapted to rotate around a first axis A and an magnetic item adapted to rotate around an second axis B and positioned at a first distance along a third axis, where the first distance is such that the magnetic field of the magnetic element has sufficient magnitude within the magnetic item to force it to rotate around the second axis B when the magnetic element rotates around the first axis A, without the two elements contacting each other physically.

Description

NON-TOUCHING ROTATIONAL CONTACT

BACKGROUND

Turbine engines, such as gas or air turbines, come in many shapes and sizes, where fore example the hot gases produced by the burning fuel drive vanes connected to a shaft that spins the compressor of the turbine. One general matter for turbine engines is the need to get the main shaft spinning to start the engine.

This starting process normally uses an electric motor to spin the main turbine shaft where the motor is positioned outside the engine and uses a shaft and gears to connect to the main shaft. It spins the main shaft until there is enough air blowing through the compressor and the combustion chamber to light the engine. Fuel starts flowing and an igniter similar to a spark plug ignites the fuel. Then fuel flow is increased to spin the engine up to its operating speed.

For systems where the starter is physically connected to e.g. the main turbine shaft such as when the starter is an electric motor, it is well know that when the turbine spins up and starts producing thrust the electric motor needs to be prevented from damage by disconnecting it from the turbine, but still it has been realized that the electric motors often last only for a limited amount of starts before tending to break down and needs replacement. This is a problem for systems where the frequency of expected starts is high.

SUMMARY OF THE INVENTION

The present invention introduces a non-touching rotational contact that with advantage could be introduced in a turbine engine as a solution to the problems of the starter electric motors breaking.

The non-touching rotational contact however could also be introduced in a wide range of other systems.

The non-touching rotational contact of the present invention introduces a magnetic element adapted to rotate around a first axis A and an magnetic item adapted to rotate around an second axis B and positioned at a first distance along a third axis , where the first distance is such that the magnetic field of the magnetic element has sufficient magnitude within the magnetic item to force it to rotate around the second axis B when the magnetic element rotates around the first axis A, without the two elements contacting each other physically.

Such a non-touching rotational contact would ensure there to be no physical contact from the driver of the starter (such as an electric motor) to the turbine and thus protecting it from being damaged.

The non-touching rotational contact according to the present invention operates by using the rotation of the magnetic element to induce a Lorentz current in the magnetic item and thus an electric field of opposite polarity, hence the magnetic item needs not itself to be paramagnetic but to be electrically conductive.

Unlike ordinary electric motor configuration also operating on the principle of permanent magnets interacting with electromagnetic elements in a rotational manner, the magnetic element and magnetic item of the present invention are not arranged coaxially, but rather arranged with front surfaces facing each other in the direction of the third axis C.

In the embodiment where used as contact from a starter to a turbine engine, the magnetic element and the magnetic item has the first position during the startup of the gas turbine, and shifts to the second position when said turbine engine has started rotating un-aided. In this manner any interaction from the turbine engine to the starter is prevented during ordinary operation of the turbine engine.

FIGURES

FIG. 1 Illustration of the non-touching rotational contact used in a turbine engine.

Fig. 2A and 2B Embodiments of the magnetic element and magnetic item parts of the non-touching rotational contact of the present invention.

DETAILED DESCRIPTON OF THE INVENTION

The present invention introduces a non-touching rotational connection suitable to be applied as contact from a starter to a turbine, thus could also be referred to as an interactor.

Fig. 1 illustrates such a typical turbine (1) where the present invention with advantage could be implemented, but may just as well be applied in a wide range of other applications.

The turbine (1) illustrated includes an impeller attached to the turbine (1) via the main shaft (2) and a starter (3), and turbines of this kind further comprises a pressure-cabin air compressor, turbine stator blades, combustion chambers and air inlets among other parts, where such parts and how a gas turbine operates is not part of the present invention, but is well known and thus need no further explanation here.

The driving part (4) of the starter could be an electric motor, and actuator or other means adapted to rotate a magnetic element (5) around a first axis A. The magnetic element could advantageously be a permanent magnet, but could alternatively be an electromagnet.

The magnetic element interacts with a magnetic item (6) adapted to rotate around a second axis B and positioned at a first distance along a third axis C. In the illustration the three axis A, B and C merges into one and the same axis, but this is not necessary the case for the invention to function, two or all of the axis A, B and C could be parallel but being offline with a relative distances an d /or two or all of the axis A, B and C could have relative inclinations with respective relative angles.

The main issue is the magnetic element (5) in a contact mode (but non-touching) is sufficiently close to the magnetic item (6) for the magnetic field to have sufficient magnitude, or strength, to induce a Lorentz current in the magnetic item (6) when the magnetic element (5) has a rotation relative to the magnetic item (6). The magnetic item (6) thus is made of a material suitable for inducing Lorentz current (such as diamagnetic materials) without leaving the material permanently magnetized, thus it is not being ferromagnetic or strongly paramagnetic. One such suitable material is Cupper, but other materials may be just as suitable.

The induced Lorentz current forms in the magnetic item (6) a secondary magnetic field of opposite polarity to the one from the magnetic element (5) thus forming a situation with two repulsive magnetic fields being slightly shifted in their rotation, and thus a torque is induced making the magnetic item (6) rotating around the second axis B when the magnetic element (5) rotates around a first axis A.

One essential element of the present invention is that the magnetic item (6) is not in itself magnetic, the magnetism in it being induced by the rotating magnetic element (5). However, it needs to be electrically conductive.

The magnetic element (5) may be made of one material (or a mixture / alloy of materials) throughout, or alternatively comprises one bulk material having one property and inserted additional materials having other properties. Fig. 2A illustrates one such situation where the bulk material (7) of the magnetic element (5) is formed as a disc of aluminum having embedded permanent magnets (8) encircling the center of the magnetic element at a radius. The figure shows a front view of the magnetic element (5). This however is only one of a plural of different possible configurations.

In the same manner the magnetic item (6) could be formed as a disc facing the magnetic element (5) when positioned in the turbine (as seen in Fig. 1), and may as the magnetic element (5) be made of one material (or a mixture / alloy of materials) throughout, or alternatively comprises one bulk material having one property and inserted additional materials having other properties. In Fig. 2B it is illustrated as made of one material only such as Cupper, where the figure shows a front view and a side view respectively of such and embodiment magnetic item (6).

When starting the turbine (1) the driver (4) of the magnetic element (5) makes it rotate and trough the described process it forces a rotation of the magnetic item (6) too. The magnetic item (6) is connected to the turbine such as to its main shaft (2) and thus forces it to rotate enabling a startup of the turbine (1).

When the turbine (1) gets sufficient torque to continue un-aided then in one embodiment of the present invention one of the magnetic element (5) and the magnetic item (6) changes position along the third axis C moving it to a second distance relative to the other of said two elements. This gives a reduced magnitude of the magnetic field interaction within the magnetic item (6). In this manner the parts composing the starter (3) (such as the driving part (4) like an electric motor) is protected from the turbine (1).

In the preferred but not limiting embodiment of the present invention it is the magnetic element (5) that changes position by a shift to a position at a second distance to the magnetic item (6), the second distance being larger than the first distance.

In the illustration of Fig. 1 the magnetic element (5) is positioned in connection with the starter (3) and the magnetic item (6) is positioned in connection with the turbine (1), but the opposite configuration having the magnetic element (5) positioned in connection with the turbine (1) and the magnetic item (6) positioned in connection with the starter (3) would also apply to the present invention.

It should be emphasized that the basic of the present invention relate to the nontouching contact of the magnetic element (5) and magnetic item (6) where a rotation of the one forces a rotation of the other, and this may easily be implemented in other systems than turbines (1).

Claims

Claim 1: Non-touching rotational contact comprising a magnetic element (5) adapted to rotate around a first axis A and an magnetic item (6) adapted to rotate around an second axis B and positioned at a first distance along a third axis C, where the first distance is such that the magnetic field of the magnetic element (5) has sufficient magnitude within the magnetic item (6) to force it to rotate around the second axis B when the magnetic element (5) rotates around the first axis A, without the two elements (5, 6) contacting each other physically.
Claim 2: Non-touching rotational contact according to claim 1, where the magnetic item (6) is not paramagnetic but electrically conductive.
Claim 3: Non-touching rotational contact according to claim 2, where the rotation of the magnetic element (5) induces a Lorentz current in the magnetic item (6) and thus a electric field of opposite polarity.
Claim 4: Non-touching rotational contact according to claim 1,2 or 3, where the magnetic element (5) and magnetic item (6) are arranged non-coaxially with front surfaces facing each other with front surfaces facing each other in the direction of the third axis C.
Claim 5: Non-touching rotational contact according to one of claims 1 to 4, where at least one of the magnetic element (5) and magnetic item (6) may change position along the third axis C thus giving second distance relative to the other of said two elements (5, 6. with a reduced magnitude of the magnetic field interaction within the magnetic item (6).
Claim 6: Non-touching rotational contact according to any of claims 1 -5, where the first axis A and second axis B is parallel.
Claim 7: Non-touching rotational contact according to any of claims 1 -6, where the third axis C is parallel to either first axis A, second axis B or both.
Claim 8: Non-touching rotational contact according to any of the preceding claims operating in a starter (3) for a turbine engine (1) where either the magnetic element (6) or the magnetic item (6) is in connection to a driver (4) making the element (5, 6) rotate, and where the other element (5, 6) is connected to the main shaft (2) of the turbine engine (1).
Claim 9: Non-touching rotational contact according to claim 8, where the magnetic element (5) and the magnetic item (6) has the first position during the startup of the gas turbine, and shifts to the second position when said turbine engine (1) has started rotating un-aided.