Oxygen Sensor for High Temperature Kilns and Method of Fabrication
OwnerMark C. Smithinventor
Life of this patent
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Abstract
An oxygen sensor for a gas, coal, oil or wood fired kiln that is orders of magnitude cheaper than the current state of the art oxygen sensors. It uses a TiO2 tip sintered between and bridging a 1 mm spacing between a pair of 22 gauge Nichrome® series 90 round annealed resistance wires (0.64 mm diameter and having 0.648 Ohms/ft resistance). The Nichrome® 90 wires do not contact each other. One of the wires is a signal wire that resides down the center of an insulating sheath and the other wire is a ground wire that is wound around the outside of a high temperature ceramic insulating sleeve. The sensor needs no temperature compensation and exhibits an approximate 50,000 ohms of resistance change from a neutral (ambient) atmosphere and a fully reduced atmosphere.
Claims6
An oxygen sensor for use with a high temperature hydrocarbon fired kiln, comprising:
- a probe having a distal probe end and a proximal probe end, said probe made of an insulating sleeve with a signal wire made of an alloy consisting of 90% Nickel, and 10% chrome, said signal wire passing through the approximate center of said insulating sleeve and a common wire made of an alloy consisting of 90% Nickel, and 10% chrome, spirally wrapped around said insulating sleeve;
- said both signal wire and said common wire extending beyond said insulating sleeve and ending in a parallel, spaced configuration;
- a sintered TiO2 tip bridging between and onto said signal wire and said ground wire at said distal probe end, said sintered tip made of a mixture of TiO2 powder mixed in a one to one ratio by volume with a PVA glue and heated to above 2200 degrees F.;
- a first copper wire coupled to said first signal wire at said proximal end of said probe;
- and
- a second copper wire coupled to said common wire at said proximal end of said probe;
- an electronic connector operably connected to said first wire and said second wire, said connector adapted for connection to an oxygen concentration display device.
A method of making a low cost oxygen sensor, comprising the steps of:
- constructing a probe having a 90% Nickle and 10% Chromium signal wire down the center of an insulating sleeve and a 90% Nickle and 10% Chromium common wire wound around said insulating sleeve, with both said signal and said common wires extending for a minimum of 10 mm beyond an end of said insulating sleeve;
- coating said signal wire and said common wire in a one to one by volume, slurry of TiO2 and PVA glue in the region that extends a minimum of 10 mm beyond said end of said insulating sleeve;
- applying a stream of low heat air to said mixture of TiO2 and PVA glue until any moisture is driven off and said TiO2 and PVA glue slurry is solid;
- repeating the steps of coating and applying warm air to build up a tip of TiO2 and PVA glue that is at least 7 mm long on said signal wire and said common wire and bridges between said signal wire and said common wire.
Dependencies are inferred from the claim text.