Abstract: An electrically commutated motor includes a first module to measure a current in a coil of the motor, and a second module to adjust timing of commutation of the motor based on the current measurement.

Abstract: A switched reluctance motor having a rotor and a stator is disclosed. The stator has a plurality of peripherally spaced stator poles, each being defined by an inner curvilinear face, which is generally aligned with the curvilinear faces of adjacent stator poles in a circumferential path. A plurality of stator inserts are also provided that are disposed between adjacently spaced stator poles. Each stator insert has a curvilinear face that is generally aligned in the same circumferential path with the curvilinear faces of adjacently spaced stator poles to reduce siren noise. Each stator insert is also constructed to include at least one pocket opposite its curvilinear face for receiving a magnet to facilitate positioning of the rotor relative to the stator poles. Each stator insert is further provided with oppositely extending arms for receiving and mounting a pre-wound stator coil or “wound-in-place” coils.

Abstract: An improved design for a switched reluctance motor is disclosed that keeps the motor cool during operation and thereby improves the performance and reliability of the motor. The improved design employs three centrifugal fans mounted to the motor shaft, which are used to create two independent airflow paths, one of which cools the electronic components of the motor. The improved design also divides the functions performed by a single printed circuit board into two circuit boards, an upper circuit board and a lower circuit board. Another feature of the improved design includes locating the position/speed sensing encoder immediately below one of the centrifugal cooling fans. The disclosed construction provides for increased dissipation of heat that is generated by the motor and its electronic components. In this configuration, the printed circuit boards and other electronic components are located in such a manner that air can be circulated in a path to remove heat from these components.

Abstract: A switch and speed control assembly for use in a wet/dry utility vacuum or blower is disclosed. The switch and speed control assembly provides a single rotary control actuator for turning the vacuum or blower on and off, for infinitely varying the speed of the motor, and for providing a momentary boost control. The switch and speed control assembly includes a thumb wheel fitted to the shaft of a voltage varying potentiometer, a snap action switch in operable relation to the exterior edge of the thumb wheel, and a compression spring contained beneath the thumb wheel. As the thumb wheel is rotated in an increasing "on" direction, the contacts of the snap action switch are closed, allowing electric current to flow to the motor of the wet/dry utility vacuum or blower. The voltage levels in the motor, and correspondingly the speed of the motor, are controlled by varying the potentiometer voltage through rotation applied to the thumb wheel.

Abstract: A power converter and controller system for a motor using an inductive load, such as a switched reluctance motor, which provides enhanced motor performance. The improved power converter and controller system accomplishes this by using a return bus having a storage device for storing energy. A controller monitors both the in the inductive load and the energy stored in the storage device and dynamically controls the storage device and the inductive load to dynamically control the current in the inductive load and the voltage on the storage device.

Abstract: A filter condition sensor and indicator is disclosed. A filter condition sensor and indicator that responds to the presence of a predetermined collection of material in a filter operatively positioned in an output air flow path. A small by-pass air flow path is connected to the output air flow path and is separate from the filter. A heated thermistor is positioned in the by-pass air flow path. Electrically connected in series with the heated thermistor is an indicator light that illuminates when the resistance in the circuit is decreased due to predetermined cooling of the heated thermistor. In this way, a predetermined collection of material in the filter increases the flow of air in the small by-pass air flow path for cooling the heated thermistor and for lowering the resistance in the circuit to illuminated the indicator light.

Abstract: A variable speed direct drive drill press/router is disclosed. The drill press/router includes a housing supported above a horizontal bed which contains a generally vertically extending spindle that is rotatably mounted within and partially extends below the housing. A manually engageable or motor driven driver axially moves the spindle predetermined distances toward and away from the horizontal bed. For driving the spindle, a switched reluctance motor is mounted at the upper end of the housing for rotary driving engagement at a desired range of predetermined speeds throughout the entire range of axial movement of the spindle. The lower end of the spindle is capable of interchangeably receiving a workpiece rotating tool such as a drill or router for drilling or routing a workpiece.

Abstract: A control circuit (1) for use in a humidifier (H). A capacitor functioning as a humidity sensor (55) includes a sulphonated fluorocarbon material acting as the dielectric (57) of the capacitor. The material is sandwiched between sheets (59a, 59b) of a screen material which act as plates of the capacitor. An RC oscillator (53) has a variable frequency output and incorporates the capacitor. Changes in the dielectric value of the material due to sensed changes in humidity produce changes in the oscillator output frequency. A DC voltage is supplied to the oscillator. The amount of voltage impressed on the sensor at relatively high-humidity levels is controlled to prevent leakage currents caused when the material is exposed thereto. The generation of such leakage currents otherwise adversely effects sensor operation. Operation of the circuit to control operation of the humidifier is also described.

Abstract: A system for encoding position information includes a grid of evenly spaced, parallel conductive lines fixed with respect to one of two mechanical parts, the grid being disposed along the line of movement of the parts. Two pairs of interdigitated electrodes capacitively sense the conductive lines of the grid, the electrodes being fixedly disposed on the other mechanical part. Decoding circuitry is responsive to the electrodes for providing relative movement information. The fingers of each electrode are disposed substantially parallel to the grid lines, the capacitance of each electrode with respect to the grid being a function of the proximity of the fingers of that electrode to the grid lines. The decoding circuitry includes first and second latches whose outputs are a function of which electrode of its corresponding pair has the greater capacitance to the grid. The second pair of interdigitated electrodes is offset from the first pair such that its ouput differs from that of the first pair.

Abstract: A power saw includes a motor for driving a saw blade or the like around its rotational axis to cut a workpiece. The position of the rotational axis with respect to a reference position is sensed and a manually operated keyboard is provided for entering a desired change in the position of the rotational axis. Positioning motors are provided along with circuitry which is responsive to the entering of a desired change in the position of the rotational axis of the saw blade for moving the axis correspondingly.

Abstract: An induction heating apparatus which includes an induction coil with an associated load and a resonant inverter circuit coupled to a DC power supply for energizing the heating coil. The inverter circuit includes a gate controlled thyristor which is cyclically gated to produce a conductive first period followed by an nonconductive second period in order to energize the heating coil. A diode of opposite polarity to the gate controlled thyristor is coupled in parallel therewith and has an impedance connected in series. The voltage across this series impedance is coupled to the gate of the gate controlled thyristor. The inverter circuit additionally includes an improper load check circuit for disabling the gating of the thyristor in the event of an improper load coupled to the heating coil, and a gate triggered timing generator for adjusting the timing of production of thyristor gate pulses to maintain substantially constant power to proper heating coil loads.

Abstract: A cycle-select switching system for automatic appliances and the like of the type for selectively performing any one of a plurality of distinct operating cycles. The switching system comprises selection means having a plurality of outputs, each corresponding to one of the operating cycles, and a momentary contact switch for producing a control signal of variable time duration. The selection means is responsive to the control signal by sequentially advancing to the output defined by a selected time duration of the control signal and thereby initiating the operating cycle corresponding thereto.

Abstract: A circuit for the automatic starting of an induction motor of the type having a sensing means for producing a signal proportional to the main winding current and control means for allowing current flow through a start winding only when energized by a start winding control signal. The starting circuit includes means for continuously producing a variable threshold level which is proportional to a condition capable of affecting the current level in the main winding and which defines an adjustable threshold switching level. A comparison means continuously compares the adjustable threshold switching level to the signal proportional to the main winding current and, whenever the latter signal exceeds the former, the comparison means generates a start winding control signal which activates the start winding control means thereby establishing current flow through the start winding.