Rotor to stator temporary interconnection element for bearingless electric machine

A temporary interconnection element to be installed between the rotor and the stator of a bearingless electric machine, for example during its transport, storage or assembly is described herein. The interconnection element is so designed that the rotor may be secured to an external assembly, such as for example the shaft of an internal combustion engine, before the element is removed from its interconnection position.

FIELD OF THE INVENTION

The present invention relates to electric machines. More specifically, the present invention is concerned with a temporary interconnection element to be mounted between a rotor and a stator of a bearingless electric machine.

BACKGROUND OF THE INVENTION

Electric machines are well known in the art. They are used to transform mechanical energy to electrical energy or vice versa by means of two coaxial generally cylindrical bodies: a first one being fixed: the stator, the other one being coaxially rotatable relative to the other, the rotor.

Some electric machines are self-supportive in that they include bearings or other frictionless elements to rotatably mount the rotor to the stator, while others, which are referred to as bearingless electric machines, do not include any means to support the rotor with respect to the stator. They are often used when the rotor is mounted to a drive shaft that is axially and radially fixed. For example, when an electric generator is directly mounted to an ICE (Internal Combustion Engine), i.e. when the stator is secured to the casing of the ICE and when the rotor is secured to the driving shaft of the ICE.

However, the transport of bearingless electric machines is problematic since there is no bearing to maintain the spatial relationship between the rotor and the stator of the machine. For the same reason, the installation and removal of the bearingless machine to/from an ICE for example is also problematic. These problems are compounded when the electric machine is of the permanent magnet type.

OBJECTS OF THE INVENTION

An object of the present invention is therefore to provide a temporary interconnection element between the rotor and the stator of an electric machine, for example during the transport, storage and installation of a bearingless electric machine to an external assembly, such as the shaft of an ICE.

SUMMARY OF THE INVENTION

More specifically, in accordance with the present invention, there is provided an interconnection element for temporary rotor to stator interconnection, the rotor and stator being intended for use in a bearingless electric machine, the element comprising: a first anchoring portion to be removably secured to the rotor; a second anchoring portion to be removably secured to the stator; and at least one passage extending through the element for fastening the rotor to a shaft.

More specifically, there is provided an interconnection element for temporary rotor to stator interconnection, the rotor and stator being intended for use in a bearingless electric machine, the element being generally in the form of a disc, comprising: a recessed central portion defining a first anchoring portion to be removably secured to the rotor and including passages extending through the element for fastening the rotor to an external element without removal of the element; and a peripheral flange defining a second anchoring portion to be removably secured to the stator.

According to a second aspect of the present invention, there is provided a bearingless electric machine including: a stator; a rotor; an interconnection element for temporary interconnecting the rotor and the stator; the interconnection element allowing the rotor to be connected to an external assembly without requiring removal thereof.

Finally, according to a third aspect of the present invention, there is provided a process for mounting a bearingless electric machine provided with a rotor and a stator to a working machine provided with a rotatable shaft, the process comprising: using a temporary interconnection element for interconnecting the rotor and stator of the bearingless electric machine; securing the rotor of the bearingless electric machine to the rotatable shaft of the working machine; and releasing the temporary interconnection element from at least one of the rotor and stator.

Other objects, advantages and features of the present invention will become more apparent upon reading the following non restrictive description of preferred embodiments thereof, given by way of example only with reference to the accompanying drawings.

DETAILED DESCRIPTION

Generally stated, an embodiment of the present invention relates to a temporary interconnection element to be installed between the rotor and the stator of a bearingless electric machine, for example during its transport or storage. The interconnection element is so designed that the rotor may be secured to an external assembly, such as for example the shaft of an ICE (Internal Combustion Engine), while the element remains in its interconnection position.

A bearingless electric machine10according to an illustrative embodiment of the present invention will now be described first with reference toFIG. 1of the appended drawings.

The bearingless electric machine10includes a casing12, a stator14mounted to the casing12via fasteners15, a rotor16and a temporary interconnection element18for temporary interconnecting the rotor16and the stator14as will be described hereinbelow in more detail.

As will be apparent to one skilled in the art, the electric machine10is of the type having an internal stator/external rotor. However, more conventional electric machines, having an internal rotor, could benefit from the general concept of the present invention.

The temporary interconnection element18is mounted to the casing12via six fasteners20(only two shown) and to the rotor16via five fasteners22(only three shown). Since the stator14is mounted to the casing via fasteners15(only one shown), the rotor16is indirectly connected to the stator14via the interconnection element18. Even though the stator14is illustrated mounted to the casing via fasteners15, other fastening means such as soldering, clamping, etc, can also be used.

The temporary interconnection element18will now be described in more detail with reference toFIG. 7.

The temporary interconnection element18is in the form of a generally ring-shaped body having a recessed central portion24and a peripheral flange26and defining a central aperture28and a central axis29.

The recessed central portion24defines a first anchoring portion to be removably secured to the rotor16. The first anchoring portion allows receiving fasteners via five fastener apertures30allowing the element18to be mounted to the rotor via fasteners22(seeFIG. 1).

The recessed central portion24further comprises five larger apertures32for providing a passage extending through the element18for fastening the rotor16to an external element such as the rotatable shaft38(seeFIG. 2) without removal, or even contact in the case of the present embodiment, of the interconnection element18.

The peripheral flange26, which is radially distanced from the central portion24, defines a second anchoring portion to be removably secured to the stator14via the casing12. More specifically, the peripheral flange26includes six slotted apertures34allowing the interconnection of the element18to the casing12via fasteners20(seeFIG. 1).

FIG. 2of the appended drawings, illustrates the electric machine10mounted to an ICE36provided with a rotatable shaft38that is axially and radially fixed with respect to the remaining of the ICE36. More specifically, the casing12of the machine10is secured to the ICE36via fasteners40. It is to be noted that the rotor16of the machine10is not yet secured to the shaft38.

InFIG. 3, the rotor16is mounted to the shaft38via five fasteners42(only three shown) that pass through the larger apertures32of the element18(seeFIG. 7). These fasteners42go through smaller apertures (not shown) of the rotor16and are secured to the shaft38via threaded apertures (not shown) of the shaft38.

When this installation of the fasteners42is done, the element18is no longer required to maintain the integrity of the rotor16relatively to the stator14and may be removed from the electric machine10. Indeed, since the rotor16is fixedly mounted to the shaft38and the stator14is fixedly mounted to the ICE36via the permanent interconnection of the stator14with respect to the casing12, the spatial relationship between the rotor16and the stator14is maintained via the ICE36.

Accordingly,FIG. 4illustrates the electric machine10where the fasteners22(FIG. 1) securing the temporary interconnection element18to the rotor16have been removed.

The element18may then be removed completely from the casing12via the removal of the fasteners20, as can be seen fromFIG. 5.

The temporary interconnection element18may then be stored or discarded since it is no longer required to maintain the spatial relationship between the rotor16and the stator14, as long as the electric machine10is mounted to the ICE36.

Alternatively and optionally, as illustrated inFIG. 6, it is possible to store the element18directly into the stator14by flipping it and by securing it in its original place with the original fasteners20. Indeed, since the central portion24of the element18is recessed (seeFIG. 7), the element18does not contact the rotor16in any way when the element18is flipped around. The temporary interconnection element18is therefore said to be in its storage position. This is interesting since it ensures that the temporary interconnection element18will be available should it become necessary to remove the electric motor10from the ICE36.

Even though the present invention has been described with reference to an electric machine10including a casing12, the temporary interconnecting element18can be secured directly to the stator14via its second anchored portion26.

Of course, one skilled in the art will understand that the dimension, number of apertures and overall shape of the element18illustrated herein are partly based on the operational requirements of the element18and partly based on the configuration of the rotor and stator of the electric machine and of the shaft of the ICE and may therefore differ without departing from the spirit and nature of the present invention.

For example, according to another embodiment (not shown) the slotted apertures may be replaced by round apertures. The peripheral flange26may extend at an angle from the central portion24so as to facilitate its securing to a casing or a stator having different geometries than those illustrated inFIGS. 1-6.

Also, depending on the configuration of the bearingless electric machine, the larger apertures32, which provide a passage extending through the element18for fastening the rotor16to an external element, may be radially distanced from the apertures30for example.

Finally, since the central aperture28serves no anchoring or fastening purposes, it can alternatively be filled, yielding an interconnecting element having generally the shaped of a disc. Of course, the interconnecting element can have other shapes.