Electricity: motive power systems – Field or secondary circuit control – Plural – diverse or diversely connected or controlled field...
Reexamination Certificate
2000-02-08
2001-08-07
Nappi, Robert E. (Department: 2837)
Electricity: motive power systems
Field or secondary circuit control
Plural, diverse or diversely connected or controlled field...
C318S777000, C310S185000
Reexamination Certificate
active
06271639
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention generally relates to capacitor start single phase induction motors and, in particular, to a 2/4 pole motor employing a partial 2-pole winding starting and to 4/8 and 4/6/8 pole motors employing a partial 4-pole winding starting.
2. Description of the Prior Art
Capacitor start single phase induction motors having two or more pole configurations are useful in multi-speed applications. For example, some washing machines employ 4/6/8 pole capacitor start single phase induction motors because such motors are able to adjust speed for various cycles within a certain speed range without the need for a complicated and expensive variable frequency controller. There is a continuing need to design such motors to provide good performance for both running and starting at a low cost of materials and manufacture. The running performance includes evaluating such factors as torque, speed, current, temperature rise, efficiency, size and other factors. The starting performance includes evaluation of the speed-torque curves of the motor. The minimum torque or torque dip at a speed between zero to the speed at breakdown torque can be a limiting factor for starting. Sometimes, a compromise needs to be made among the running performance, starting performance, material cost, tooling or other factors.
Some 4/6/8 pole motors in production employ basically independent 4-pole, 6-pole and 8-pole main windings and a 4-pole auxiliary winding. Only a small portion of a 6-pole winding is shared with a 4-pole winding. To reduce the size of the motor and save active material, a new approach to sharing the 4-pole and 8-pole windings has been developed and is described in co-invented, co-assigned PCT patent application Ser. No. PCT/US99/11235, filed May 20, 1999, entitled SINGLE PHASE THREE SPEED MOTOR WITH SHARED WINDINGS, the entire disclosure of which is incorporated herein by reference. One advantage of the shared winding approach is that it improves running performance without an increase in material cost. However, to reconnect the main winding from a 4-pole configuration to an 8-pole configuration, or visa versa, one more contact, such as a single pole single throw switch, is needed either as part of the starting switch or as part of the external circuit of the motor. If the additional contact is implemented as part of the starting switch, the starting switch will require three switches and four contacts. This implementation makes the starting switch more complicated and expensive to retool and produce. On the other hand, if the additional contact is implemented as part of the external circuit of the motor, the additional contact would be in the form of a timer or a relay. However, since the 4-pole to 8-pole reconnection is implemented by the external circuit, the motor cannot use 4-pole starting for 8-pole running without affecting the starting performance. Using 6-pole starting can avoid this problem (see PCT/US99/11235 noted above). However, when the motor employs 6-pole starting and 4-pole running, a torque dip occurs during the transfer from 6-pole to 4-pole. To cancel the dip, a time delay relay is required to maintain the 6-pole auxiliary winding in the circuit 40 ms longer during transfer from starting to running. The relay is an additional component providing additional cost.
There is a need for a 4/8 pole and 4/6/8 pole motors which employ 4-pole starting so that many of the above problems are avoided. There is also a need for a 2/4 pole motor which employs 2-pole starting so that many of the above problems are avoided.
SUMMARY OF THE INVENTION
It is an object of this invention to reduce material costs in a capacitor start single phase induction motor by employing a partial winding starting.
It is another object of this invention to reduce material costs while improving performance of such a motor.
It is another object of this invention to employ partial winding starting in a capacitor start single phase induction motor without the need for a retooled starting switch.
It is another object of the invention to employ only a single 4-pole auxiliary winding in a 4/8 pole and 4/6/8 pole capacitor start single phase induction motor.
It is another object of the invention to employ the entire 8-pole configuration of the main winding as part of the 4-pole configuration of the main winding in a 4/8 pole and 4/6/8 pole capacitor start single phase induction motor so that there is no independent 8-pole winding.
In one form, the invention is a motor comprising a stator core, a rotor in rotational relationship with the stator core, a main winding on the core having at least a 4-pole configuration and an 8-pole configuration, a 4-pole auxiliary winding on the core, and a switching circuit. The switching circuit selectively simultaneously energizes a portion only of the 4-pole configuration of the main winding and the 4-pole auxiliary winding when starting the motor for energizing the main winding in the 8-pole configuration.
In another form, the invention is a motor comprising a stator core, a rotor in rotational relationship with the stator core, a main winding on the core having at least a 2-pole configuration and an 4-pole configuration, a 2-pole auxiliary winding on the core and a switching circuit. The switching circuit selectively simultaneously energizes a portion only of the 2-pole configuration of the main winding and the 2-pole auxiliary winding when starting the motor for energizing the main winding in the 4-pole configuration.
In another form, the invention is a motor comprising a stator core, a rotor in rotational relationship with the stator core, a main winding on the core having at least an n-pole configuration and an m-pole configuration where n and m are even numbers and n<m, a n-pole auxiliary winding on the core and a switching circuit. The switching circuit selectively simultaneously energizes a portion only of the n-pole configuration of the main winding and the n-pole auxiliary winding when starting the motor for energizing the main winding in the m-pole configuration. Other objects and features will be in part apparent and in part pointed out hereinafter.
REFERENCES:
patent: 2946941 (1960-07-01), Jin
patent: 4103213 (1978-07-01), Landgraf
patent: 4322665 (1982-03-01), Landgraf
patent: 4463303 (1984-07-01), Kirschbaum
patent: 4467257 (1984-08-01), Douthart et al.
patent: 4473788 (1984-09-01), Kirschbaum
patent: 4476422 (1984-10-01), Kirschbaum
patent: 4947098 (1990-08-01), Vlasak
patent: 5825111 (1998-10-01), Fei
patent: 5883488 (1999-03-01), Woodward
patent: 6175209 (2001-01-01), Fei
patent: 2031657 (1980-04-01), None
patent: 015459 (1983-01-01), None
patent: 230388 (1987-10-01), None
patent: 228946 (1988-09-01), None
Fei, et al., “An Experimental Study of Single-Phase Induction Motor Starting Performance and Its Dependency on Winding Harmonics”, IEEE-IAS Annual Meeting, Paper No. EM-4-2-76, Oct., 1995.
Rajaraman, et al., IEEE, “Theory and Design of Part-Winding Starting”, IEEE Transactions on Energy Conversion, vol. 14, no. 1, Mar. 1999, pp. 31-36.
Duda Rina I.
Emerson Electric Co.
Nappi Robert E.
Senniger Powers Leavitt & Roedel
LandOfFree
Capacitor start single phase induction motor with partial... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Capacitor start single phase induction motor with partial..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Capacitor start single phase induction motor with partial... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2517774