A METHOD TO UTILIZE A VEHICLE’S OWN EXHAUST GAS TO SMOKE TEST THE EVAP SYSTEM
Publication Date: 2014-Mar-04
The IP.com Prior Art Database
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A METHOD TO UTILIZE A VEHICLE'S OWN EXHAUST GAS TO SMOKE TEST THE EVAP SYSTEM
Vehicles sold in North America are required to perform diagnostics on various powertrain subsystems. One such subsystem is the Evap shown below. For federal states, the Evap system is monitored for a leak size of 0.04". For green states, the system is monitored for a leak size of 0.02". If Evap leaks are found the MIL is lit. Once the MIL is lit, customers bring vehicle to the dealership garage for service. Typically, a smoke tester is used to check where in the Evap system the leak is. Smoke testers are expensive and can run in the thousands of dollars. They have ability to generate smoke and at the same time infer the leak size. Smoke testers also generate Nitrogen gas. It is undesirable to introduce shop air that is rich in oxygen into the Evap system as oxygen can be volatile when mixed with fuel vapors. Spontaneous combustion could occur if hydrocarbons mix with oxygen. Also, technicians are typically not interested in the leak size. They are interested in finding the leak location and repairing it.
This system utilizes the vehicle's own exhaust gas to generate smoke. Exhaust gas is composed mainly of Nitrogen gas, which is what the smoke testers generate. Oxygen is not a component of the exhaust gas. The vehicle exhaust gas is passed through a condenser to absorb the H2O byproduct in the exhaust gas. Water is filtered out since it could harm the internal valves inside the...