METHOD AND SYSTEM FOR DIAGNOSIS OF GAS LEAKAGE IN A GAS-POWERED VEHICLE

摘要

The invention relates to a method for automatic diagnosis of gas leakage in a gas system, intended primarily for a gas- powered vehicle, which gas system comprises at least one gas tank which via a line system is in communication with an engine via a high-pressure valve situated near to the gas tank, a pressure regulator situated downstream of the high- pressure valve, a first low-pressure valve situated thereafter, a further second low-pressure valve situated downstream of the latter, and at least one pressure sensor. The invention is effected by the first and second low-pressure valves respectively being alternately closed first, before every second stopping of the engine, to bring about a maximum pressure drop across whichever low-pressure valve is being checked at the time, and thereby make it possible to diagnose even small leaks, by closing the not yet closed low-pressure valve, by measuring the gas pressure downstream of the first low-pressure valve, by storing the measured pressure value in a memory, by measuring the gas pressure before the next start, by comparing current pressure with the pressure value stored in the memory, by evaluating whether the expected pressure difference obtains, and by determining whether leakage has occurred, i.e. whether the low-pressure valve closed first has leaked. The invention relates also to a system for automatic diagnosis of any leakage in the valves.