Flow metering method and flowmeter

A flowmeter for metering a flow rate of fluid passing through a housing by feeding the fluid into the housing, stocking the fluid in the housing and feeding out the fluid to the outside of the housing, characterized by comprising:

• a metering flow path disposed in said housing for passing the fluid in connection with the feed-in or feed-out of the fluid into/from said housing;
• a reference flow path disposed in said housing, the fluid stocked being filled in said reference flow path so as to freely flow;
• a thermal type metering flow sensor disposed in said metering flow path;
• and a thermal type reference flow sensor disposed in said reference flow path, wherein the electrical output corresponding to a metered flow rate achieved by using said thermal type metering flow sensor is corrected on the basis of the electrical output corresponding to a reference flow rate achieved by using said thermal type reference flow sensor to thereby achieve a flow rate value.

A method of metering a flow rate of fluid by making the fluid under metering flow into a metering flow path, achieving the electrical output corresponding to a metered flow rate of the fluid under metering in said metering flow path by an electrical circuit constructed so as to contain a thermal type flow sensor disposed in said metering flow path by utilizing the fact that a heat absorption amount from the thermal type flow sensor to the fluid under metering corresponds to the metered flow rate of the fluid under metering in the metering flow path, and performing conversion to the flow rate value corresponding to the electrical output corresponding to the metered flow rate by using pre-created calibration curves, characterized in that:

• the calibration curve is created for a reference fluid;
• the fluid under metering is filled in a reference flow path so as to freely flow therethrough, and the electrical output corresponding to a reference flow rate of the fluid under metering in said reference flow path is achieved by an electrical circuit constructed so as to contain a thermal type reference flow sensor disposed in said reference flow path by utilizing the fact that a heat absorption amount from said thermal type reference flow sensor to the fluid under metering corresponds to the reference flow rate of the fluid under metering in said reference flow path;
• and
• the output-corresponding value corresponding to the electrical output corresponding to the metered flow rate or the flow rate value achieved by the conversion using the calibration curve is corrected by using the electrical output corresponding to the reference flow rate, thereby correcting the error of the flow rate value due to the difference in thermal property of the fluid under metering from the reference fluid.

A flowmeter for metering a flow rate of fluid passing through a housing by feeding the fluid into the housing, stocking the fluid in the housing and feeding out the fluid to the outside of the housing, characterized by comprising:

• a metering flow path disposed in said housing for passing the fluid in connection with the feed-in or feed-out of the fluid into/from said housing;
• a reference flow path disposed in said housing, the fluid stocked being filled in said reference flow path so as to freely flow;
• a first thermal type flow sensor disposed in said metering flow path;
• a second thermal type flow sensor disposed in said reference flow path;
• a first flow rate detection circuit constructed so as to contain said first thermal type flow sensor;
• and a second flow rate detection circuit constructed so as to contain said second thermal type flow sensor, wherein conversion from both of the first output-corresponding value corresponding to a first output value achieved in said first flow rate detection circuit on the basis of the thermal interaction between the fluid in said metering flow path and said first thermal type flow sensor and the second output-corresponding value corresponding to a second output value achieved in said second flow rate detection circuit on the basis of the thermal interaction between the fluid in said reference flow path and said second thermal type flow sensor to the flow rate value is performed on the basis of a correction output-corresponding value achieved by correcting the first output-corresponding value on the basis of the second output-corresponding value by using a calibration curve for reference fluid.

A flowmeter for metering a flow rate of fluid passing through a housing by feeding the fluid into the housing, stocking the fluid in the housing and feeding out the fluid to the outside of the housing, characterized by comprising:

• a metering flow path disposed in said housing for passing the fluid in connection with the feed-in or feed-out of the fluid into/from said housing;
• a reference flow path disposed in said housing, the fluid stocked being filled in said reference flow path so as to freely flow;
• a first thermal type flow sensor disposed in said metering flow path;
• a second thermal type flow sensor disposed in said reference flow path;
• a first flow rate detection circuit constructed so as to contain said first thermal type flow sensor;
• and a second flow rate detection circuit constructed so as to contain said second thermal type flow sensor, wherein conversion to a flow rate value is performed by using a calibration curve for reference fluid on the basis of a first output-corresponding value corresponding to a first output value achieved in said first flow rate detection circuit on the basis of the thermal interaction between the fluid in said metering flow path and said first thermal type flow sensor, and a corrected flow rate value is achieved by multiplying the flow rate value by a correction parameter corresponding to a second output value achieved in said second flow rate detection circuit on the basis of the thermal interaction between the fluid in said reference flow path and said second thermal type flow sensor.