Wire heated tube with temperature control system, tube type detection, and active over temperature protection for humidifier for respiratory apparatus

A conduit for use in a respiratory apparatus for delivering breathable gas to a patient, the conduit comprising:

• a tube;
• a helical rib on an outer surface of the tube;
• a control system configured to control the conduit comprising:
• a power supply to provide power to the conduit;
• an over-temperature control circuit to prevent overheating of the conduit;
• a heating control circuit configured to control heating of the conduit to obtain a predetermined temperature;
• and
• a sensing circuit including a sensing resistor configured to indicate the temperature of a sensor positioned in the conduit;
• and a bias generator circuit configured to provide a first source voltage to the sensing circuit so that the temperature of the conduit is monitored whether the conduit is being heated or not;
• a tube circuit comprising at least three wires supported by the helical rib in contact with the outer surface of the tube and a temperature sensor connected to at least one of the three wires to provide a signal to a power supply and the control system;
• and
• a first cuff connected to a first end of the tube and a second cuff connected to a second end of the tube, the first cuff being configured to be connected to a patient interface of the respiratory apparatus and the second cuff being configured to be connected to a flow generator or humidifier of the respiratory apparatus.

A PAP system configured for delivering breathable gas to a patient, comprising:

• a flow generator to generate a supply of breathable gas to be delivered to the patient;
• a humidifier including a heating plate to vaporize water and deliver water vapor to humidify the supply of breathable gas;
• a heated tube configured to heat and deliver the humidified supply of breathable gas to the patient;
• and
• a control system comprising:
• a power supply to provide power to the heated tube;
• an over-temperature control circuit to prevent overheating of the heated tube;
• a heating control circuit configured to control heating of the heated tube to obtain a predetermined temperature;
• a sensing circuit including a sensing resistor configured to indicate the temperature of a sensor positioned in the heated tube;
• and a bias generator circuit configured to provide a first source voltage to the sensing circuit so that the temperature of the heated tube is monitored whether the heated tube is being heated or not,
• wherein the power supply is configured to supply power to the heating plate and the heated tube, and
• the control system is configured to control the power supply to prevent overheating of the heating plate and the heated tube.

A method of controlling a heated conduit connected to a respiratory apparatus, the method comprising:

• supplying power to the heated conduit;
• continuously monitoring a temperature of a sensor positioned in the heated conduit;
• and
• controlling the power supply to the heated conduit via a control system to obtain a predetermined temperature, the control system comprising:
• a power supply to provide power to the heated conduit;
• an over-temperature control circuit to prevent overheating of the heated conduit;
• a heating control circuit configured to control heating of the heated conduit to obtain a predetermined temperature;
• a sensing circuit including a sensing resistor configured to indicate the temperature of a sensor positioned in the heated conduit;
• and
• a bias generator circuit configured to provide a first source voltage to the sensing circuit so that the temperature of the heated conduit is monitored whether the heated conduit is being heated or not.