Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1985-10-23
1988-07-12
Budd, Mark O.
Electrical generator or motor structure
Dynamoelectric
Rotary
310 12, 310162, 310154, 310266, H02K 3700
Patent
active
047572205
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an electrodynamic vernier machine.
An electrodynamic vernier machine is known of the type comprising:
two parts separated from each other by a gap, said parts being capable of moving relative to each other in a direction such that the average width of the gap remains constant; and
means co-operating magnetically with a first one of said parts to create a magnetic field having 2p poles moving along said direction, p being an integer;
the first part being constituted by a magnetic frame comprising N teeth forming N slots, where N is an integer multiple of p, with the slots being open to the gap and being uniformly spaced along said direction; and
the second part comprising M elements disposed along the said direction, where M is an integer multiple of p and differs from N by a number T=t.times.p, where t is an integer which is small relative to N/p.
For example, a rotary motor of this type comprises a rotor mounted to rotate about an axis and a coaxial stator including N slots and N teeth. A polyphase winding is disposed in the slots creating a rotating field in the rotor. The M elements of the rotor are constituted by M teeth forming M slots, where M is greater than N. A magnet is fixed coaxially in the rotor in such a manner as to create a continuous magnetic field which passes through the gap and penetrates into the stator.
Generally speaking, known electrodynamic vernier machines are machines of the homopolar synchronous type whose two relatively movable parts comprise two respective rows of teeth facing each other, with the the number of teeth in one row being different from the number of teeth in the other row.
These machines have drawbacks. they must have a narrow gap which, by virtue of the magnetic circuit saturating, reduces the ampere-turns and consequently the machine torque. Further, the magnetic flux of these machines includes a homopolar component which does not produce any torque but which does contribute to saturating the magnetic circuit. As a result, the bulk of the machine may be prohibitive in certain applications.
The aim of the present invention is to mitigate these drawbacks.
The present invention provides an electrodynamic vernier machine of the above-mentioned type, characterized in that:
each of the M elements comprises two flux generators oriented in opposite directions, these elements interfering with the N teeth of the first part to create in said first part a magnetic field having 2p poles and capable of latching in synchronous manner with the 2p-pole moving field created by the said means which co-operate magnetically with the first part.
Several particular embodiments of electrodynamic vernier machines are described below by way of example with reference to the accompanying drawings, in which:
FIG. 1 is a diagram in partial longitudinal section through a vernier motor of known type;
FIG. 2 is a cross-section showing a portion of the profile of the the teeth in the rotor and the stator of the motor shown in FIG. 1;
FIG. 3 is a cross-section showing a portion of another vernier motor of known type;
FIG. 4 is a graph showing the operation of the motor shown in FIG. 3;
FIG. 5 is a cross-section showing a portion of a step-down vernier of known type; and
FIGS. 6 to 12 are cross-sections showing portions of seven different vernier type motors in accordance with the present invention.
The vernier motor shown in FIG. 1 comprises a stator 1 having a winding 12. The stator 1 is made up from an assembly of toothed magnetic laminations and the winding 2 is of the 2p-pole polyphase type and is lodged in the slots situated between the teeth of the stator. The stator 1 is circularly cylindrical about an axis 3 and is annular in section. A toothed rotor 4, likewise built-up from an assembly of magnetic laminations is mounted to rotate about the axis 3 and is disposed in the internal cylindrical volume of the stator 1, being separated therefrom by a cylindrical gap 5. A cylindrical magnet 6 is fixed coaxially in the rotor 4. The magnet 6 is fixed in the rotor
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Alsthom
Budd Mark O.
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