Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1982-05-20
1984-03-27
Duggan, Donovan F.
Electrical generator or motor structure
Dynamoelectric
Rotary
310 12, H02K 706
Patent
active
044397020
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to electric machines and particularly concerns electric motors having a helical stator.
DESCRIPTION OF THE PRIOR ART
Known in the art is an electric motor (British Pat. No. 945,225 Nat.Cl. H2A, Published Dec. 23, 1963) allowing helical movement of the rotor to be effected. In this motor, a stator carrying a polyphase armature winding has the form of a hollow cylinder provided with helical grooves on the inner surface thereof. The rotor of the motor, disposed within a stator bore, is constructed in the form of a cylinder and is further provided with helical grooves and salient poles forming the main magnetic field.
When the winding is connected to an a.c. power supply, the rotor moves helically. The speed of this movement is determined by the frequency of the terminal voltage, which frequency is selected to be relatively low, e.g. such that the motor make 1 r.p.m. If the windings are connected to a d.c. power supply, the rotor will be held in a fixed position due to the presence of salient poles. To achieve a required position of the rotor, the frequency must be lowered gradually or suddenly to zero.
In the case where the winding is supplied with a three-phase alternating current, a rotatory magnetic field is formed, in which field the rotor starts to synchronously rotate since it is provided with salient poles. Simultaneously, the helical grooves of the rotor are set along the helical grooves of the stator, thereby resulting in the movement of the rotor also along the axis in the direction which depends on the direction of rotation.
However, the motors of the above type are characterized by inherent shortcomings caused by low adjusting properties of a.c. electric machines operating from an industrial feeding voltage network, said shortcomings consisting mainly in that the range of monitoring a frequency of rotation thereof is narrow, and therefore the range of monitoring the speed of helical movement of the rotor in the given device is narrow as well.
Frequency regulators of the feeding voltage, acceptable for industrial use and allowing the frequency of rotation of synchronous and asynchronous motors to be continuously controlled, have not at present left experimental studies.
SUMMARY OF THE INVENTION
The invention provides an electric motor which ensures a helical movement of a driven working member of an industrial mechanism, due to a special formation of excitation and control magnetic fields and continuous control of linear speed of the latter, and would allow the range of monitoring the speed of the helical movement to be expanded.
The problem set forth is solved by an electric motor, comprising a stator provided with a helical magnetic core within whose grooves is laid an armature winding, and a rotor disposed within a stator bore and provided with salients for forming a main magnetic field, disposed around the rotor along a helical line, the length of the salients being equal to .alpha..delta...tau., and the distance therebetween being (2-.alpha..delta.)..tau., where .alpha..delta. is a coefficient of a rated pole arc, and .tau. is a pole pitch of the motor. According to the invention, in the magnetic core is provided an additional groove wherein is laid an excitation winding, the portions of each turn of the magnetic core whereon an armature winding and an excitation winding are disposed have a length which ensures axial alignment of the grooves for placing the armature winding within all the magnetic core turns. The salients forming the main magnetic field have a length which is equal to the pole pitch of the motor and are disposed at a distance from one another which is equal to the pole pitch of the motor.
Such an arrangement of the motor makes it possible to accomplish continuous control of the helical movement of the rotor, and consequently of a working member of an industrial mechanism driven by this motor, said control being carried out by changing the feeding voltage either of the armature winding or of the excitation winding. The above m
REFERENCES:
patent: 3824420 (1974-07-01), Marinus et al.
patent: 3889165 (1975-06-01), Van
patent: 3898487 (1975-08-01), Sobiepanek et al.
patent: 4197488 (1980-04-01), Kant
Belikov Viktor T.
Chelak Viktor G.
Ivlev Anatoly D.
Duggan Donovan F.
Odessky Politekhnichesky Institut
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