Capacitive liquid level sensor

摘要

Described herein is technology for, among other things, controlling a pump submersed in a liquid, where the pump includes a plurality of capacitive sensors. The capacitive sensors include a first capacitive sensor and a second capacitive sensor disposed above the first capacitive sensor. The technology involves sensing liquid levels with the capacitive sensors, activating the pump after the second capacitive sensor detects the liquid in a normal mode of operation, deactivating the pump after the first capacitive sensor no longer detects the liquid in the normal mode of operation, detecting a failure of one or more capacitive sensors, and adjusting the operation of the pump to compensate for the failure of the one or more capacitive sensors.

主权项

1. A method of controlling a pump for use with a plurality of capacitive sensors, the plurality of capacitive sensors including a first capacitive sensor and a second capacitive sensor positioned above the first capacitive sensor, the method comprising:
sensing liquid levels with the plurality of capacitive sensors in a normal mode of operation; activating the pump to pump the liquid after the second capacitive sensor detects the liquid in the normal mode of operation; deactivating the pump after the first capacitive sensor no longer detects liquid in the normal mode of operation; detecting a failure of at least one of the plurality of capacitive sensors; entering a first error mode of operation from a plurality of error modes of operation after detecting the failure, the first error mode of operation allowing continued activating and deactivating of the pump to allow the pump to continue to pump the liquid based on sensing the liquid levels with at least one of the remaining plurality of capacitive sensors that is functioning, and entering a second error mode of operation from the plurality of error modes when none of the plurality of capacitive sensors are functioning, the second error mode of operation allowing continued activating and deactivating of the pump to allow the pump to continue to pump the liquid by periodically activating the pump for a first predetermined time period, and pausing for a second predetermined time period between the periodic pump activations; actively checking one or more of the plurality of capacitive sensors that failed for determining if one or more of the plurality of capacitive sensors that failed are no longer considered failed; and returning to the normal mode of operation if all the plurality of capacitive sensors that failed are no longer considered failed.