Control of humidifier chamber temperature for accurate humidity control

A breathing assistance system for delivering a flow of gases to a patient for therapeutic purposes, comprising:

• a blower unit comprising an inlet and an outlet, the blower unit having an adjustable, variable speed fan unit adapted to draw gases from the inlet and to deliver a flow of gases over a range of flow rates to the outlet;
• a humidifier unit which in operation provides heat to a volume of water in a humidifier chamber, the humidifier unit comprising an inlet port, an exit port, and a heater base, the humidifier unit further operational to permit a flow of gases from the outlet of the blower unit to enter the humidifier unit via the inlet port, pass through the humidifier unit and become heated and humidified, and exit the humidifier unit via the exit port, the blower unit and the humidifier unit being integrated into the same housing;
• a heater plate adapted to heat contents of the humidifier unit by providing heat energy to the heater base of the humidifier unit;
• a heater plate temperature sensor which in operation measures the temperature of the heater plate;
• an exit port temperature sensor which in operation measures a temperature relating to the flow of gases exiting the humidifier unit;
• and
• a controller,
• wherein the exit port of the humidifier connects, in use, to a conduit configured to deliver the flow of gases from the exit port to the patient via an interface, the conduit comprising a heater wire which in operation heats the flow of gases within the conduit, the conduit including a patient end temperature sensor which in operation measures a temperature of the flow of gases within the conduit close to the patient;
• wherein the controller:
• controls the speed of the fan unit to deliver a flow of gases to the outlet at a desired user set flow rate;
• receives data from the heater plate temperature sensor, data from the patient end temperature sensor, and data from the exit port temperature sensor;
• and
• controls the temperature of the gases provided to the patient to achieve a target dew point temperature by:
• controlling the heater wire based on the data from the patient end temperature sensor and data from the exit port temperature sensor;
• and controlling the heater plate based on the data from the heater plate temperature sensor and data from the exit port temperature sensor.

A breathing assistance system for delivering a flow of gases to a patient for therapeutic purposes, comprising:

• a blower unit comprising an inlet and an outlet, the blower unit having an adjustable, variable speed fan unit adapted to draw gases from the inlet and to deliver a flow of gases over a range of flow rates to the outlet;
• a humidifier unit which in operation provides heat to a volume of water in a humidifier chamber, the humidifier unit comprising an inlet port, an exit port, and a heater base, the humidifier unit further operational to permit a flow of gases from the outlet of the blower unit to enter the humidifier unit via the inlet port, pass through the humidifier unit and become heated and humidified, and exit the humidifier unit via the exit port;
• a heater plate adapted to heat contents of the humidifier unit by providing heat energy to the heater base of the humidifier unit;
• a heater plate temperature sensor which in operation measures the temperature of the heater plate;
• an exit port temperature sensor which in operation measures a temperature relating to the flow of gases exiting the humidifier unit;
• and
• a controller,
• wherein the exit port of the humidifier connects, in use, to a conduit configured to deliver the flow of gases from the exit port to the patient via an interface, the conduit comprising a heater wire which in operation heats the flow of gases within the conduit, the conduit including a patient end temperature sensor which in operation measures a temperature of the flow of gases within the conduit close to the patient;
• wherein the controller:
• controls the speed of the fan unit to deliver a flow of gases to the outlet at a desired user set flow rate;
• receives data from the heater plate temperature sensor, data from the patient end temperature sensor, and data from the exit port temperature sensor;
• and
• controls the temperature of the gases provided to the patient to achieve a target dew point temperature by:
• controlling the heater wire based on the data from the patient end temperature sensor and data from the exit port temperature sensor;
• and controlling the heater plate based on the data from the heater plate temperature sensor and data from the exit port temperature sensor.

A breathing assistance system for delivering a flow of gases to a patient for therapeutic purposes while reducing condensation in a conduit, comprising:

• a blower unit comprising an inlet and an outlet, the blower unit having an adjustable, variable speed fan unit adapted to draw gases from the inlet and to deliver a flow of gases over a range of flow rates to the outlet;
• a humidifier unit which in operation provides heat to a volume of water in a humidifier chamber, the humidifier unit comprising an inlet port, an exit port, and a heater base, the humidifier unit further operational to permit a flow of gases from the outlet of the blower unit to enter the humidifier unit via the inlet port, pass through the humidifier unit and become heated and humidified, and exit the humidifier unit via the exit port;
• a heater plate adapted to heat contents of the humidifier unit by providing heat energy to the heater base of the humidifier unit;
• a heater plate temperature sensor which in operation measures the temperature of the heater plate;
• an exit port temperature sensor which in operation measures a temperature relating to the flow of gases exiting the humidifier unit;
• and
• a controller,
• a conduit configured to deliver the flow of gases from the exit port to the patient via an interface, the conduit comprising a heater wire which in operation heats the flow of gases within the conduit, the conduit further comprising a patient end temperature sensor which in operation measures a temperature of the flow of gases within the conduit close to the patient,
• wherein the exit port of the humidifier connects, in use, to the conduit;
• wherein the controller:
• controls the speed of the fan unit to deliver a flow of gases to the outlet at a desired user set flow rate;
• receives data from the heater plate temperature sensor, data from the patient end temperature sensor, and data from the exit port temperature sensor;
• and
• controls the temperature of the gases provided to the patient to achieve a target dew point temperature by:
• controlling the heater wire based on the data from the patient end temperature sensor and data from the exit port temperature sensor;
• and controlling the heater plate based on the data from the heater plate temperature sensor and data from the exit port temperature sensor.