Sunbeam Corporation Limited

Oster Corporation

James B Cockroft

Peter J Ernster

Daniel L Sukow

Ernest V Canamero

Richard A Smith

A motor speed control circuit for closed loop control of an electric motor of a household electric appliance is disclosed herein. The motor speed control circuit includes a coil adapted to be placed in proximity with a fan connected to an electric motor and producing a time varying signal in response to rotation thereof. A comparator connected to the coil generates a rectangular wave having a frequency proportional to the frequency of the coil signal. Additional means are provided for converting the rectangular wave signal, a D.C. signal having an amplitude which corresponds to the frequency of the rectangular wave. The D.C. signal is compared to a reference signal at an amplifier to produce an error signal which is fed through an opto-isolator to a conduction angle controlled thyrister. The thyrister is connected to the electric motor and a source of electric power to control the speed of the electric motor.

Motor speed control circuit

A motor control circuit is provided for an appliance or the like of the type utilizing a speed adjustment device that controls an adjustable centrifugally controlled governor device. The governor includes a switch contact arrangement which is connected in the triggering circuit of a power switching device, a TRIAC for example, for selectively connecting the motor of the appliance to the power source connections. The switch contacts of the governor device open and close as the rotational speed of the motor increases and decreases respectively from the speed selected on the speed adjustment device. A variable impedance element mechanically coupled to and adjusted by the speed adjustment device is also provided in the triggering circuit of the power switching device in series with the governor switch contacts to vary the triggering of the power switching device as the speed setting is varied. Thus, a variable speed versus motor supply voltage characteristic is provided when the governor contacts are closed. A wider range of stable speed control is provided than is obtained with a governor device alone. Low speed cogging and high speed hunting problems are also minimized. The variable impedance element in various embodiments is arranged to provide a variable impedance characteristic over a portion of the speed adjustment device range and a fixed impedance over the remainder of the range.

Speed responsive motor control circuit

An automatic control for egg cookers, baby bottle warmer, etc. is designed around a conventional slide switch of the type normally biased to the open position. Manually actuated means are provided to move the slide switch to its ON position, whereupon a mechanical latch automatically latches onto the knob of the slide switch to hold it in its ON position. When the cooking has been completed, a bi-metal releases the latch and permits the biasing means to open the switch and terminate the heating.

Automatic control for electric heating device

A bag sealer having an electrically heated wire and a pivotally mounted sealing member which is substantially parallel to and normally biased away from the wire. An integral transformer and solenoid are provided for reducing the voltage supplied to the wire and for bringing the sealing member into pressure bearing relationship with the wire. The primary winding of the transformer serves as the solenoid coil while the solenoid armature, upon being closed, completes the transformer. In order to facilitate activating the switch to energize the transformer winding, a lever extends out through the housing. Molded side pieces carry an extruded channel on which is mounted a resilient pressure bar.

Growing community of inventors

Wauwatosa, WI, United States of America

James B Cockroft