GB1594731A - Dynamo electric machines - Google Patents

Description

(54) IMPROVEMENTS IN AND RELATING TO DYNAMO ELECTRIC MACHINES (71) We, PARAFLUX LIMITED, a British Company, of 39-40, Gay Street, Bath, England, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to dynamo electric machines and to a modification of the machines forming the subject of my prior Patents Nos 1485154 and 1485304.

In Patent No. 1485154 a single phase or multi-phase dynamo electric machine includes a laminated stator having slots with at least one winding therein, arranged to be energised to provide alternating or reversing flux, and a laminated member movable with respect to the stator and having at least one short-circuited continuous loop to which there are no external connections, to form a 'null' position for the movable member where any flux path through the movable member is parallel to the plane of the said at least one loop with no flux linkage thereof, any movement of the movable member from the 'null' position causing current to flow in the said at least one loop to produce a force tending to restore the movable member of the "null" position at which the linkage of the said at least one loop with the energised stator winding(s) is a minimum. The movable member may be a rotor or a linearly moving member.

In Patent No. 1485304, switching means are provided for affecting energisation of the stator windings in a predetermined sequence to change the flux linkage in the short circuited windings to effect movement of the movable member with respect to the stator in a direction determined by the sequence of energisation of the stator windings.

The relative positions of the windings may however, be reversed with advantage for some applications, the energisation for the armature windings being on the rotor or movable member and the short circuit loops wound on or cast into the stator.

Thus, acording to one aspect of the present invention there is provided a single phase or multi-phase dynamo electric machine including a stator having at least one short-circuited winding and a movable member having at least one winding arranged to be energised to provide alternating or changing flux such as to form a 'null' position for the movable member where any flux path through the movable member is parallel to the plane of the said at least one short circuited winding with no flux linkage thereof, any movement of the movable member from the 'null' position causing current to flow in the said at least one short circuited winding to produce a force tending to restore the movable member to the 'null' position at which the linkage of the said at least one short circuited winding with the energised winding(s) of the movable member is a minimum.

According to a further aspect of the invention, switching means are provided for effecting energisation of the windings on the movable member in a predetermined sequence to change the flux linkage in the short circuited stator windings to cause movement of the movable member in a direction determined by the sequence of energisation of the windings on the ntv- able member.

The invention will now be described by way of example only with particular reference to the sole figure of the accompanying drawing which is a view of the rotor of a single phase 2-pole machine showing the relative locations of the energising windings on the rotor and short circuit windings on the stator thereof; A substantial proportion of the shortcircuited stator winding is in diametrically opposed slots X, X', the end conections being divided to pass either side of the rotor shaft. Alternatively, this diametrical substantial proportion of the short circuited winding could be divided into a pair of parallel loops. In either case, the remainder of the winding is disposed in pairs of loops parallel to the diametral portion, typified by loops Y, Y', Z, Z'. While the conductor sections (slot shapes) are drawn as circular, this is for drawing convenience only, as the slot shape can be varied to suit the designer's requirements.

The rotor is shown typically with 12 radial slots to carry the energising windings.

A winding as shown using slots 1-6 and 12-7 in series, energised by a.c., will produce flux along the coil axis which, with the rotor in the position shown can flow through the stator without linking the short-circuited loops. This therefore represents the null position of the rotor. Angular displacement either way up to but excluding 90" will produce a torque tending to restore the rotor to the null position for the reasons explained in Patent No. 1485304. While the winding is shown distributed over two slot pairs, the number of slots and distribution of concentration of the winding can be varied at the designer's discretion.

If a similar winding separately a.c. energised were provided using slots 3-10, 4-9 in series, it is clear that such a winding would be in quadrature with the original, producing a double-acting rotary solenoid which is a direct inversion of that described in Patent No. 1485154.

Similarly, providing two additional windings to that shown, one utilising slots 2-9, 3-8 in series and the other using slots 4-11, 5-10 in series, separately a.c. energised, would provide stepping windings of 60 displacement, and so on.

For machines such as rotary solenoids requiring partial rotation only, the connections to the rotor windings can conveniently be by flexible leads; for increased rotation the connections can be by means of slip rings or commutating segments on the rotor shaft.

To vary the speed-torque characteristic of the machine, the brushes of the commutator are displaced in relation to the stator, or the commutator is displaced relative to the movable member in response to any increase in torque, speed or current.

While the illustration typifies a single phase rotary 2-pole machine, it will be clear that 3 phase and multi-phase and linear versions of the machine can also be produced in this inverted form corresponding to each of the embodiments described in the said prior Patents Nos. 1485154 and 1485304. For instance, in the linear version, a movable member carrying the armature is arranged to move relatively to a stationary member carrying the short-circuit winding(s).

WHAT WE CLAIM IS: 1. A single phase or multi-phase dynamo electric machine including a stator having at least one short-circuited winding and a movable member having at least one winding arranged to be energised to provide alternating or changing flux such as to form a 'null' position for the movable member where any flux path through the movable member is parallel to the plane of the said at least one short circuited winding with no flux linkage thereof, any movement of the movable member from the 'null' position causing current to flow in the said at least one short circuited winding to produce a force tending to restore the movable member to the 'null' position at which the linkage of the said at least one short circuited winding with the energised winding(s) of the movable member is a minimum.

2. A dynamo electric machine as claimed in Claim 1 and including switching means for effecting energisation of the windings of the movable member in a predetermined sequence to change the flux linkage in the short circuited stator windings to effect movement of the movable member in a direction determined by the sequence of energisation of the windings on the movable member.

3. A dynamo electric machine as claimed in Claim 1 wherein said at least one short-circuited winding on the stator includes a diametral loop with end connections divided circumferentially and a plurality of parallel loops.

4. A dynamo electric machine as claimed in Claim 3 wherein the terminals of the said at least one winding on the movable member are conected to an energising source, flexible leads or via respective segments of a commutator.

5. A dynamo electrical machine as claimed in Claim 4 wherein to vary the speed-torque characteristic of the machine, the brushes of the commutator are displaced in relation to the stator, or the commutator is displaced relative to the movable member in response to any increase in torque, speed or current.

6. A dynamo electric machine as caimed in any one of claims 1 to 5 wherein the movable member is arranged to move past the stator in a linear manner.

7. A dynamo electric machine substantially as hereinbefore described and as shown in the acompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. circular, this is for drawing convenience only, as the slot shape can be varied to suit the designer's requirements. The rotor is shown typically with 12 radial slots to carry the energising windings. A winding as shown using slots 1-6 and 12-7 in series, energised by a.c., will produce flux along the coil axis which, with the rotor in the position shown can flow through the stator without linking the short-circuited loops. This therefore represents the null position of the rotor. Angular displacement either way up to but excluding 90" will produce a torque tending to restore the rotor to the null position for the reasons explained in Patent No. 1485304. While the winding is shown distributed over two slot pairs, the number of slots and distribution of concentration of the winding can be varied at the designer's discretion. If a similar winding separately a.c. energised were provided using slots 3-10, 4-9 in series, it is clear that such a winding would be in quadrature with the original, producing a double-acting rotary solenoid which is a direct inversion of that described in Patent No. 1485154. Similarly, providing two additional windings to that shown, one utilising slots 2-9, 3-8 in series and the other using slots 4-11, 5-10 in series, separately a.c. energised, would provide stepping windings of 60 displacement, and so on. For machines such as rotary solenoids requiring partial rotation only, the connections to the rotor windings can conveniently be by flexible leads; for increased rotation the connections can be by means of slip rings or commutating segments on the rotor shaft. To vary the speed-torque characteristic of the machine, the brushes of the commutator are displaced in relation to the stator, or the commutator is displaced relative to the movable member in response to any increase in torque, speed or current. While the illustration typifies a single phase rotary 2-pole machine, it will be clear that 3 phase and multi-phase and linear versions of the machine can also be produced in this inverted form corresponding to each of the embodiments described in the said prior Patents Nos. 1485154 and 1485304. For instance, in the linear version, a movable member carrying the armature is arranged to move relatively to a stationary member carrying the short-circuit winding(s). WHAT WE CLAIM IS:

1. A single phase or multi-phase dynamo electric machine including a stator having at least one short-circuited winding and a movable member having at least one winding arranged to be energised to provide alternating or changing flux such as to form a 'null' position for the movable member where any flux path through the movable member is parallel to the plane of the said at least one short circuited winding with no flux linkage thereof, any movement of the movable member from the 'null' position causing current to flow in the said at least one short circuited winding to produce a force tending to restore the movable member to the 'null' position at which the linkage of the said at least one short circuited winding with the energised winding(s) of the movable member is a minimum.

2. A dynamo electric machine as claimed in Claim 1 and including switching means for effecting energisation of the windings of the movable member in a predetermined sequence to change the flux linkage in the short circuited stator windings to effect movement of the movable member in a direction determined by the sequence of energisation of the windings on the movable member.

3. A dynamo electric machine as claimed in Claim 1 wherein said at least one short-circuited winding on the stator includes a diametral loop with end connections divided circumferentially and a plurality of parallel loops.

4. A dynamo electric machine as claimed in Claim 3 wherein the terminals of the said at least one winding on the movable member are conected to an energising source, flexible leads or via respective segments of a commutator.

5. A dynamo electrical machine as claimed in Claim 4 wherein to vary the speed-torque characteristic of the machine, the brushes of the commutator are displaced in relation to the stator, or the commutator is displaced relative to the movable member in response to any increase in torque, speed or current.

6. A dynamo electric machine as caimed in any one of claims 1 to 5 wherein the movable member is arranged to move past the stator in a linear manner.

7. A dynamo electric machine substantially as hereinbefore described and as shown in the acompanying drawing.