# US 5,708,314 A · Multi-rotor A.C. electric drive device

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- Number: US 5,708,314 A
- Document ID: US5708314A
- Status: Granted
- Kind: A
- Application number: 08/535,166
- Filed: 1995-10-23
- Granted: 1998-01-13
- Earliest claimed: 1993-04-27
- Inventors: Mingyuen Law
- Web page: https://patentgrep.com/patent/US5708314A

## CPC

- H02K 16/025: {with rotors and moving stators connected in a cascade (cascade arrangement of an asynchronous motor with another dynamo-electric motor or converter H02K17/34)}
- F16H 3/10: with one or more one-way clutches as an essential feature
- H02K 16/02: Machines with one stator and two {or more} rotors
- B60K 1/02: comprising more than one electric motor
- B60K 6/448: Electrical distribution type
- B60K 2006/262: {the motor or generator are used as clutch, e.g. between engine and driveshaft}
- F16H 3/727: {with at least two dynamo electric machines for creating an electric power path inside the gearing, e.g. using generator and motor for a variable power torque path}
- H02K 7/10: Structural association with clutches, brakes, gears, pulleys or mechanical starters
- Y02T 10/62: Hybrid vehicles
- H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53})
- F16H: GEARING
- B60K: ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

A multi-rotor A.C. electric drive device comprises a stator capable of producing a rotating or an alternating magnetic field and at least two rotors capable of producing an electromagenetic torque at asynchronous speed. The rotors are respectively called the main rotor and the auxiliary rotors. In low speed operating mode of said device, the electromagnetic torque of the auxiliary rotor is amplified through a transmission portion and drives an output element together with the main rotor; after the auxiliary rotor is accelerated to the synchronous speed, an automatic unloading device releases the auxiliary rotor from the driving engagement with the output element. Examples illustrating several types of electromagnetic portion, transmission portion and the automatic unloading device are given.

## Claims

### Claim 1

An A.C. electric device used for driving a machine, including an electromagnetic portion;
said electromagnetic portion including a stator and at least a main rotor and an auxiliary rotor; said stator having a core for conducting magnetic flux, and a winding capable of generating a rotating or an alternating magnetic field when a suitable A.C. power is supplied; said main and auxiliary rotors also having their own respective cores for conducting magnetic flux, and both said rotors being capable of producing torques at asynchronous speed under the effect of a rotating or an alternating magnetic field;
wherein said main rotor has a closed winding or a conductor equivalent to the closed winding for conducting induced current;
said electromagnetic portion has a first closed magnetic circuit and a second closed magnetic circuit both linked with said winding or said conductor of the main rotor;
the first magnetic circuit links with said winding of the stator, and includes the core of the stator and a part of the core of the main rotor, but not the core of the auxiliary rotor;
the second magnetic circuit includes the other part of the core of the main rotor and at least a part of the core of the auxiliary rotor, but not the core of the stator;
whereby, the current in the winding of the stator can excite in the first magnetic circuit a main flux capable of driving the main rotor to rotate and thereby induce a current in the winding or conductor of said main rotor;
said induced current in the winding or conductor of the main rotor can excite in the second magnetic circuit a main flux capable of driving the auxiliary rotor to rotate; and
said main flux excited by the current of said stator winding in said first magnetic circuit does not pass through the core of the auxiliary rotor.

### Claim 2 (depends on 1)

An electric drive device claimed in claim 1, wherein said electric drive device further includes a transmission portion and a frame for supporting the transmission portion;
said transmission portion having several transmission elements with fixed speed ratios between each other, including an output transmission element, used for driving the mechanical loads;
said two rotors are respectively connected with one of said transmission elements, so that they can drive said output element with a respective fixed speed ratio; and
the speed ratio of said main rotor relative to the output element is less than the speed ratio of said auxiliary rotor relative to the same.

### Claim 3 (depends on 2)

An electric drive device claimed in claim 2,
further including an automatic unloading device which can automatically free said auxiliary rotor from driving said output element, when said auxiliary rotor is accelerated to have a certain speed while the electric drive device speeding up.

### Claim 4 (depends on 3)

An electric drive device claimed in claim 3, characterised in that:
said unloading device includes an automatic switch having at least one normally closed contact;
said auxiliary rotor has one wire wound winding;
said winding has closed circuits for conducting the induced current in every phase;
each said closed circuit has at least one pair of said normally closed contact connected in series;
while the said drive device speeding up, when said auxiliary rotor is accelerated to a certain speed, said normally closed contacts will automatically open, so that said closed circuit of every phase of said rotor winding being cut off.

### Claim 5 (depends on 3)

An electric drive device claimed in claim 3, characterised in that:
said automatic unloading device includes a one-way clutch;
a transmission element in said transmission portion is connected to another transmission element or the frame by said one-way clutch;
when said one-way clutch is coupled, said auxiliary rotor can drive said output element with a fixed speed ratio; when said one-way clutch is released, said auxiliary rotor will freely float relative to said output element;
if said auxiliary rotor is fixed and the main rotor is rotating in its predetermined positive direction, said one-way clutch will be released.