The Development Of The Fuel System Leak Detector

With the awareness of environmental standard enhanced, people gradually recognize the importance of the exhaust emission, and the government raised the standard of the exhaust emission. To comply with the standard of the emission of pollutant , it's necessary to do the online test for leakage and venting of the fuel system during the inspection of conformity of production.With more and more shortening of the tact timing for the automobile producing, it's a immediate need to detect the leakage of the oil system in synchronizing step. Comparing the container with smaller size, detecting the larger one with 90L is still difficult. In the domestic, the equipments for testing leakage and venting of the fuel system are mainly imported from foreign countries, although some research units and firms have made many efforts for the development of these equipments which still can't reach the standard due to the susceptibility to the change of temperature.Due to the concrete conditions of the automobile's fuel system, a measure and control system based on industrial PC and programmable controller is proposed in this thesis, and use micro differential pressure sensor, rigid symmetry air pipe loop and embedded system by using micro differential pressure principle to measure pressure. Inflating the container by high precision pressure regulating valve in the second inflating phase to compensate the balance of the pressure in the detecting system, we can shorten the detecting time and impove the precision. Data of differential pressure which are acquired on line are handled with least square fit to erase noise as the criterion of the leakage level. The equipment we've developed has been running well for half a year in a automobile manufacture firm so far.