Sensor array for smart frost diagnostics

Inventors

Gao, Zhiming • Nawaz, Kashif • Fricke, Brian A. • Gluesenkamp, Kyle R.

Assignees

UT Battelle LLC

Abstract

Systems and methods implementing a frost sensor comprising a substrate (S); and sub-sensors disposed on the substrate. The sub-sensors comprising: a resistance-based sub-sensor (RSS) formed of a first trace disposed on S in a winding pattern and configured to measure a temperature; a capacitance-based sub-sensor formed of a second trace defining a first electrode and a third trace defining a second electrode (wherein (i) the first and second electrodes comprise interdigitated fingers or other interdigitated structures (including, but not limited to, round, spiral interdigitated electrodes, etc.) configured to detect a change in capacitance due of frost, ice or water, and (ii) the second trace is integrally formed with the first trace); and another RSS formed of a fourth trace defining a third electrode and a fifth trace defining a fourth electrode (wherein (i) the third and fourth electrodes comprise interdigitated fingers or other interdigitated structures (including, but not limited to, round, spiral interdigitated electrodes, etc.) configured to detect a change in resistance due to the frost, ice or water, and (ii) the fourth trace is integrally formed with the third trace).

Core Innovation

The invention relates to a smart frost diagnostics frost sensor array for frosting and defrost control in an HVAC/refrigeration environment. The sensor includes an integrally formed single sensor with multiple sub-sensors disposed on a substrate, including a first resistance-based sub-sensor configured to measure temperature and a capacitance-based sub-sensor configured to detect a change in capacitance due to frost, ice or water present on a surface of the frost sensor.

The capacitance-based sub-sensor is formed of a second trace defining a first electrode and a third trace defining a second electrode, where the first and second electrodes comprise a plurality of interdigitated fingers. The second trace is integrally formed with the first trace of the first resistance-based sub-sensor. The sensor further includes a second resistance-based sub-sensor formed of a fourth trace defining a third electrode and a fifth trace defining a fourth electrode, where the third and fourth electrodes comprise a plurality of interdigitated fingers to detect a change in resistance due to frost, ice or water.

In operation, the invention measures a surface temperature of the external object using the first resistance-based sub-sensor, detects change in capacitance due to frost, ice or water using the capacitance-based sub-sensor, and detects a change in resistance due to the frost, ice or water using the second resistance-based sub-sensor. A processor uses capacitance plus resistance plus temperature to dynamically detect frost growth/thickness, identify residual frost, melting water or ice during defrost, determine substrate surface wet versus dry, attribute wetness to rain versus humidity, and make and validate water versus ice versus frost classifications.

Claims Coverage

The independent claims comprise 2 inventive features: an integrally formed frost sensor on a single substrate, and a corresponding method for operating the frost sensor by measuring temperature and detecting capacitance and resistance changes due to frost, ice, or water.

Across the independent claims, the core inventive approach is an integrally formed single-piece frost sensor with a winding-pattern resistance trace for temperature measurement, a capacitance-based sub-sensor using interdigitated electrodes to detect capacitance changes from frost, ice or water, and a second resistance-based sub-sensor using interdigitated electrodes to detect resistance changes from frost, ice or water.

Stated Advantages

Documented Applications