US PATENT CLASS 388
Class Notes


Current as of: June, 1999
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388 /   HD   ELECTRICITY: MOTOR CONTROL SYSTEMS



DEFINITION

Classification: 388/

STATEMENT OF CLASS SUBJECT MATTER

This class and Class 318, Electricity: Motive Power Systems are the generic loci for systems of electrical control of electric motors. See Lines With Other Classes, below, for a further explanation of this line.

Note: This class is being developed in stages from old Class 318, Electricity: Motive Power Systems. As other sections of Class 318 are reclassified, they will be added hereto.

TYPES OF MOTORS

Note: At the present stage of development of this class, only the following types of motor are included.

1. Direct Current (DC) Commutating Motor: An electric motor designed to operate on direct current and having a commutator electrically connected to a winding of the motor.

MODES OF MOTOR CONTROL

Note: At the present stage of development of this class, only the following modes of motor control are included. 1. Acceleration Control: Controlling the rate of change of speed of an electric motor either (a) from zero speed to some running speed, or vice versa, or (b) from one running speed to another running speed by variation of the electric power input to the motor. Acceleration control includes deceleration control.

2. Deceleration Control: Controlling the rate of change of speed of an electric motor from a first running speed to a second (lower) running speed, including zero speed, by variation of the electric power input to the motor.

3. Running Speed Control: Controlling an electric motor so as to maintain a particular substantially constant running speed.

CLASS ORGANIZATION AND SEARCH PHILOSOPHY

This class has been structured according to a new classification philosophy known as "Concept Capture Classification" (CCC or 3C). This type of classification facilitates a new computer-based search method while continuing to support all traditional uses of the classification of patents.

Organizational Structure - The class consists of two complementary classification schedules:

1. A hierarchical schedule of subclasses (numbered from 800 to 860). The hierarchy of these subclasses follows all the rules that apply throughout the Manual of Classification. These subclasses are designed to accommodate, in general, the claimed subject matter in the patents. They differ from subclasses elsewhere in the Manual only in that they are somewhat broader and tend to contain fewer disclosure-based cross-reference copies.

2. A "term list," or schedule of Art Collections. This list is an indexing scheme with little hierarchy. These Art Collections are much like other Art Collections throughout the Manual of Classification except that care has been taken to place copies of each patent in Class 388 into each and every Art Collection for which that patent has a significant

disclosure. In other words, the "concepts" disclosed in each patent are "captured" for later reference by placing cross reference copies into all the appropriate art collections, thus the name "Concept Capture Classification."

METHOD OF CLASSIFYING NEWLY ISSUED PATENTS

When a new patent is issued in this class, copies should be placed in all appropriate subclasses of the hierarchical schedule as required by the claims. Further copies should be placed in all appropriate (according to disclosure) art collections in order to capture as much information about the patent as possible for future reference. Although cross-references based on the disclosure but not the claims may be placed in the regular subclasses, they should be limited as much as possible to the Art Collections.

SUGGESTED SEARCH STRATEGIES A traditional search of paper copies may be conducted in the same way as with any other class by selecting subclasses from among those numbered subclasses 800-860, and then looking at each patent in each subclass chosen. This approach may also be used on the "Automated Patent System" (APS) with limitation that only those patents more recent than 1975 are available for text display.

A computer-aided search (or "CCC Search") may be conducted by searching a collection of subclasses and Art Collections combined using the logical operations of the APS or of the "Classification and Search Support Information System" (CASSIS), CD/ROM version. In either of these systems one would compose a search statement that says, for example, "Give me a list of all patents which are in subclass 811 and art collections (902 and 903 and 917)." To appear on the output list a patent would have to have a copy in all of the subclasses chosen. A somewhat less restrictive search statement might be used, as for example, "Give me a list of all patents which are in subclass 811 and art collections (902 or 903 or 917).

In each of the search examples (811 and 902 and 903 and 917; and 811 and 902 or 903 or 917) note that the art collections (902, 903 and 917) are used as tools to search the subclass (811). In other words the subclass 811 is the true location of the patent but it resides there with many other patents of the same proximate function. Traditionally, it has been necessary to look at all patents in subclass 811 during a search and make judgments "on the spot" as to their relevancy to a given search condition. With a CCC search, one enters the search condition into the computer in terms of which art collections are chosen, then the computer selects from subclass 811 only those which are relevant to the given conditions. In this way the searcher, hopefully, views fewer patents which are more relevant to his search and he does not miss "hidden" or "implicit" disclosures.

An experimental computer-aided "CCC search" with specialized output is available on the CASSIS CD/ROM machines in many Patent Depository Libraries. These machines are programmed to give a search of up to three subclasses using up to six art collections. e.g., Search (811 or 819 or 831) and (902 or 903 or ... or 937) Note. This search treats the three subclasses as separate searches and prints the lists of "hits" separately for each. The output is in the form of a graph with patent number as vertical axis and art collections as horizontal axis. For each patent found as a "hit" a line is printed giving the patent number, which subclass it is in, and which art collections (of those entered) it is in. If the patent is in one subclass and one art collection (only) it is considered a "2-way hit", if it is in one (or more) subclass(es) and all six art collections it is considered a "7-way hit" and is flagged accordingly. Obviously, "7-way" hits share more features with the search statement than "2-way" hits. This special output offers the important advantage of not only identifying relevant patents, but of indicating just what is relevant about each included patent.

LINES WITH OTHER CLASSES

Where an electric motor control system is claimed in combination with a load device and the load device is claimed either (1) in general terms only (e.g., "load device", "variable load", "means actuated by motor", etc.) or (2) in specific terms, but by name only (e.g., "vehicle", "rolling mill", "gearing", etc.), classification is in this class (388) or in Class 318, Electricity: Motive Power Systems.

Where significant structure of a load device is claimed in combination with a motor control system, classification is with the load device.

Examples of classes which provide for the combination of significant load device structure and motor control include: Class 62, Refrigeration; Class 180, Motor Vehicles; Class 187, Elevator, Industrial Lift Truck, or Stationary Lift for Vehicle; Class 219, Electric Heating; Class 244, Aeronautics; Class 250, Radiant Energy; Class 290, Prime-Mover Dynamo Plants; Class 322, Electricity: Single Generator Systems; Class 360, Dynamic Magnetic Information Storage or Retrieval; Class 414, Material or Article Handling; and Class 417, Pumps.

REFERENCES TO OTHER CLASSES

SEE OR SEARCH CLASS

62, Refrigeration, appropriate subclasses, particularly 228.1+, for motor driven refrigerant compressors.

180, Motor Vehicles, appropriate subclasses for electric motor driven vehicles or vehicle subsystems.

187, Elevator, Industrial Lift Truck, or Stationary Lift for Vehicle,

289+, for an elevator with an electric drive motor controlled by means having an electric component.

200, Electricity: Circuit Makers and Breakers, appropriate subclasses for generic structure of circuit making and breaking devices.

219, Electric Heating, appropriate subclasses for electric heating apparatus including electric motors.

236, Automatic Temperature and Humidity Regulation, appropriate subclasses for temperature and humidity regulating systems which include an electric motor, particularly

74+, for electric motor actuated systems.

244, Aeronautics, appropriate subclasses for aeronautical subsystems which include electric motors.

250, Radiant Energy, appropriate subclasses for radiant energy responsive apparatus which include motors.

290, Prime-Mover Dynamo Plants, 9+, for prime-mover dynamo plants including electric traction motors; subclasses 10+, 22+, 30, 31, 36+, 38, 46, 47 and 48 for electric motor starters for prime-mover dynamo plants.

307, Electrical Transmission or Interconnection Systems,

401+, for generic saturable reactor systems.

310, Electrical Generator or Motor Structure, appropriate subclasses for generic structure of electric motors, particularly

189, for variable length or tapped windings.

322, Electricity: Single Generator Systems, electric motor systems are found throughout the class both as driving means for a generator and as a control therefor. See particularly

16, for electric motor driven generator systems having simultaneous control of motor and generator; subclass 39 for electric motor driven generator systems having electric motor control; subclasses 70, 71, 80 and 84 for generator control systems employing electric motor systems therein. See section IV of the class definition of Class 322.

323, Electricity: Power Supply or Regulation Systems,

340, for electric motor systems which control transformer tap changing; subclass 364 for electric motor systems controlled

impedance selection systems; and appropriate subclasses throughout the class for electric motor actuated or controlled phase control systems.

327, Miscellaneous Active Electrical Nonlinear Devices, Circuits, and Systems,

518+, for miscellaneous control systems. 331, Oscillators, appropriate subclasses for oscillators, per se, particularly

1+, for tunable oscillators of the automatic frequency stabilizing type; and subclasses 48, 90 and 177+ for oscillators having means for setting or controlling the frequency of a generated wave of the oscillator by varying a frequency determining element of the oscillator.

332, Modulators,

106+, for generic pulse modulation control systems.

360, Dynamic Magnetic Information Storage or Retrieval, appropriate subclasses for control of motors used in dynamic recording apparatus.

361, Electricity: Electrical Systems and Devices,

23+, for motor protection circuits which cause shut-down of the motor when predetermined conditions are met or exceeded; and subclasses 139+ for control circuits for relays and other electromagnetic-magnetic devices.

363, Electric Power Conversion Systems,

157+, for frequency conversion systems for controlling the frequency applied to load circuits in general.

364, Electrical Computers and Data Processing Systems,

130+, for generic digital data processing control systems.

377, Electrical Pulse Counters, Pulse Dividers, or Shift Registers: Circuits and Systems, 27+, for generic pulse counting systems.

414, Material of Article Handling, appropriate subclasses for control of motors used in materials or article handling apparatus.

417, Pumps,

1+, for condition responsive control of a pump driver motor.

GLOSSARY:

ANALOG

Of or pertaining to the general class of devices or circuits in which the output varies as a continuous function of the input (cf., "digital" below).

ANALOG CONTROL

A control circuit utilizing analog, as opposed to digital, signals.

ARMATURE

The moving element in an electromechanical device such as the rotating part of a generator or motor, the movable part of a relay, or the spring mounted portion of a bell or buzzer. BRUSH

A piece of conductive material, usually carbon or graphite, which rides on the commutator of a motor and forms the electrical connection between the motor and a power source.

CLOSED LOOP CONTROL

A method of control in which the power input of a motor is adjusted by a control circuit which compares a reference signal with a feedback signal proportional to an output parameter (e.g., speed) of the motor to modify the power input of the motor so as to achieve or maintain some desired operating condition of the motor (e.g., constant running speed).

COMMUTATOR

The part of a motor armature to which the armature windings are connected. It consists of a set of conductors arranged about the rotation axis of the armature and insulated from the axis and from one another. A set of stationary contacts, called "brushes" ride on the outer face of the conductors and thereby connect the armature windings to a power source.

COUNTER EMF

A voltage developed in an inductive circuit (e.g., in an armature winding) by an alternating or pulsating current. The polarity of this voltage is at every instant opposite that of the applied voltage.

DIGITAL

Of or pertaining to the general class of devices or circuits in which the output varies in discrete steps (cf., "analog" above).

DIGITAL CONTROL A control circuit utilizing digital, as opposed to analog, signals.

ELECTRIC MOTOR

A machine which transforms electrical energy into mechanical work. Note: For a description of each of the several types of electric motor, see section IA above.

FEEDBACK

The return of energy from the output of a motor to the input for the purpose of controlling the input so as to achieve or maintain a desired output condition.

FIELD WINDING

A coil of insulated wire which produces a magnetic field in the space occupied by the motor armature.

LOAD

That device, or system, which is the recipient of the mechanical work output of an electric motor.

MICROPROCESSOR

A circuit which can be programmed with stored instructions to perform a variety of functions, which functions may include, for example, one or more modes of motor control.

MOTOR CONTROL A system or device (usually an electrical circuit) which causes one or more of the operating parameters of a motor to be held constant or to be changed in a predetermined way. Note: For a description of each of the several modes of motor control, see the class definition above.

OPEN LOOP CONTROL

A method of control in which the power input to a motor is varied so as to achieve a desired running condition (e.g., constant running speed) without the use of feedback.

PHASE LOCKED LOOP

A closed loop circuit in which the output signal is compared to a reference signal and any phase difference between the two signals is used to adjust the output signal to "lock" it to the phase of the reference signal.