Thermistor flow sensor having multiple temperature points
AssigneeFisher & Paykel Healthcare Limited
InventorsRussel William Burgess, Houde Huang
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Abstract
A gases flow rate sensing system may be configured to operate in at least two different target temperature modes, based upon a measured temperature of the gases flow. In some embodiments, the gases flow sensing system may have a voltage divider containing a thermistor. The gases flow rate may be determined based upon a voltage output indicating an amount of power needed to maintain the thermistor at a target temperature as specified by the target temperature mode, and a measured temperature of the gases flow.
Claims91
A breathing assistance apparatus that provides a flow of gases to a patient, the breathing assistance apparatus comprising:
- at least one gases flow path configured to direct the flow of gases to the patient;
- a gases flow inlet configured to receive the flow of gases from a gases flow source;
- a temperature sensor configured to measure a temperature of the gases flow;
- and
- a gases flow rate sensing system configured to measure a gases flow rate of the flow of gases, wherein the gases flow rate sensing system is configured to operate in at least two different temperature modes, based upon the measured temperature of the gases flow.
A system for measuring a flow rate of a flow of gases, the system comprising:
- a thermistor circuit including a thermistor, wherein the thermistor circuit is configured to produce a voltage output and to operate in at least a first target temperature mode and a second target temperature mode;
- a temperature sensor configured to measure a gases flow temperature;
- and
- a controller coupled to the temperature sensor and the thermistor circuit, wherein the controller is configured to adjust the thermistor circuit to change between the at least first and second target temperature modes, in response to changes in the measured gases flow temperature.
A system for measuring a flow rate of a gases flow, comprising
- a thermistor circuit comprising a thermistor, the thermistor circuit having a plurality of different target temperature modes,
- wherein the thermistor circuit is configured to output a range of output voltages, the range of output voltages being the same for each of the plurality of temperature modes.
Dependencies are inferred from the claim text.