Patent ID: 8869604

Claim:
A flow rate detection device comprising a flow rate meter for outputting an output value, depending on a flow rate of a gas, the device detecting the gas flow rate by calculating the gas flow rate on the basis of the output value output from the flow rate meter, wherein it is judged if the output value output from the flow rate meter should be corrected on the basis of the flow rate of the gas passing through the flow rate meter and the change rate of the flow rate and when it is judged that the output value output from the flow rate meter should be corrected, the output value output from the flow rate meter is corrected and then, the gas flow rate is calculated on the basis of the corrected output value, wherein it is judged if the condition of the gas passing through the flow rate meter has changed from the laminar condition to the turbulent condition or vice versa or the flow direction of the gas passing through the flow rate meter has inverted and then, when it is judged that the condition of the gas passing through the flow rate meter has changed from the laminar condition to the turbulent condition or vice versa or the flow direction of the gas passing through the flow rate meter has inverted, it is judged that the output value output from the flow rate meter should be corrected, wherein a point defined by the flow rate of the gas passing through the flow rate meter and its increase rate when the condition of the gas passing through the flow rate meter has changed from the laminar condition to the turbulent condition is previously obtained as a flow rate increase condition transition point and a point defined by the flow rate of the gas passing through the flow rate meter and its decrease rate when the condition of the gas passing through the flow rate meter is previously obtained as a flow rate decrease transition point, wherein when the flow rate of the gas passing through the flow rate meter, it is judged if the point defined by the flow rate and its increase rate is the flow rate increase condition transition point and when it is judged that the point defined by the flow rate of the gas passing through the flow rate meter and its increase rate is the flow rate increase condition transition point, it is judged that the condition of the gas passing through the flow rate meter has changed from the laminar condition to the turbulent condition, and wherein when the flow rate of the gas passing through the flow rate meter decreases, it is judged if the point defined by the flow rate and its decrease rate is the flow rate decrease condition transition point and when the point defined by the flow rate of the gas passing through the flow rate meter and its decrease rate is the flow rate decrease condition transition point, it is judged that the condition of the gas passing through the flow rate meter has changed from the turbulent condition to the laminar condition.