Patent ID: 7648787

Claim:
A gas leak detection device that detects a gas leak in a fuel cell system including a fuel cell; a fuel gas supply source; a supply passage through which fuel gas is supplied from the fuel gas supply source to the fuel cell; a discharge passage through which fuel gas is discharged from the fuel cell; and a purge valve provided in the discharge passage, which adjusts an amount of fuel gas discharged from the fuel cell, the gas leak detection device comprising: a supply-amount detector provided in the supply passage, which detects an amount of supplied fuel gas, wherein the supply passage includes a first passage positioned downstream of the supply-amount detector, the fuel cell includes a second passage through which the fuel gas flows, the discharge passage includes a third passage positioned upstream of the purge valve, the gas leak detection device further comprising: a consumption-amount calculator programmed to calculate an amount of fuel gas consumed by the fuel cell; a pressure detector that detects a pressure of the fuel gas in a gas leak detection passage including the first passage, the second passage, and the third passage; a change-amount calculator that obtains a change in the pressure of the fuel gas using the detected pressure, and is programmed to calculate a change in an amount of fuel gas in the gas leak detection passage due to the change in the pressure of the fuel gas; a difference-amount calculator programmed to calculate a difference between the detected amount of supplied fuel gas and a sum of the amount of consumed fuel gas and the change in the amount of fuel gas in the gas leak detection passage by subtracting the amount of consumed fuel gas and the change in the amount of fuel gas in the gas leak detection passage from the amount of supplied fuel gas; and a fuel-gas leak detector that determines that a fuel gas leak is present in the gas leak detection passage when the difference is equal to or greater than a first predetermined value.