Therm-o-disc, Incorporated

Emerson Electric Company

Thomas C Anderson

Bernd D Zimmermann

Prasad S Khadkikar

James A Tennant

Tung-Sheng Yang

David Reynolds

Paul Mark DeSantis

Christian Georgeff

Charles A Hirsch

Bernd D Zimmerman

In many applications, where the level of a liquid needs to be monitored (and possibly controlled), it is not necessary to provide a continuous (analog) liquid level signal, but limit sensing to one (or two) discrete levels over a small level range. In this case, a ceramic substrate sensor with discrete thermistor/heater pairs provides necessary information to control the level of the fluid. Protection of the substrate from liquid (and potential contaminants) is accomplished by coating the surface with an inert glass ('glaze') layer and/or polymer layer (e.g., 'Parylene'). Packaging of the coated substrate is accomplished by protective base, epoxy, and slosh shield. Cost can be significantly reduced over a prior art multiple thermocouple based sensor design, since discrete electronic components are avoided or reduced. Also, the number of pins, and therefore electrical connections, can be significantly reduced.

Liquid level sensor using thick film substrate

A heating tank assembly for a hot water dispenser having a tank body, an electric heating element, a magnetic switch, and a movable float. The tank body has a plurality of walls and a main heating chamber for storing and heating water. At least a portion of the electric heating element is located within the main heating chamber of the tank body. The magnetic switch is electrically connected to the heating element and acts as a protective switch to the heating element. The movable float is located within the tank body and has a magnet that closes the magnetic switch when sufficient water is present in the tank. The heating tank assembly may also include at least one thermal cutout device. The thermal cutout device acts as a backup and will shut off the heating element if the heating element reaches a preset maximum temperature. The present invention also includes a method for determining whether a heating tank assembly of a hot water dispenser has little or no water by including a step of moving the float to or from the magnetic switch and closing the magnetic switch when sufficient water is present in the tank body. The present invention also includes a method for manufacturing a heating tank assembly of a hot water dispenser.

Apparatus and method for protecting a heating tank assembly of a hot water dispenser

A temperature control circuit provides for optical isolation, dry start protection, dedicated load control, manual reset, and relay control in hot water heaters and related applications. The control circuit removes power from a load at a first temperature, and includes a first optical isolation device, a first diode temperature sensor, and a first switching mechanism. The first optical isolation device controls operation of a power source, where the power source is provided to the load, such as a hot water heater heating element. The first diode temperature sensor is biased to provide a switching signal at the first temperature. The first switching mechanism is disposed between the first diode temperature sensor and the first optical isolation device, where the first switching mechanism disengages operation of the first optical isolation device in response to the switching signal. The control circuit can further include a high limit cycling circuit for disengaging operation of the power source at the second temperature. A latching circuit can be used to maintain the temperature control circuit in a switched state until a manual reset occurs.

High sensitivity diode temperature sensor with adjustable current source

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Arlington Heights, IL, United States of America

Thomas C Anderson