Bench Test Method for Fuel Tank Vent Valve Noise Induced by EVAP System Pressure Pulsation

In gasoline Powertrain systems, the evaporative emission control (EVAP) system canister purge valve (CPV) can be actuated by pulse-width modulated (PWM) signals. The CPV is an electronically actuated solenoid. The PWM controlled CPV, when actuated, creates pressure pulsations in the system. This pulsation is sent back to the rest of the EVAP system. Given the right conditions, the fill limit vent valve (FLVV) inside the fuel tank can be excited. The FLVV internal components can be excited and produce noise. This noise can be objectionable to the occupants. Additional components within the EVAP system may also be excited in a similar way. This paper presents a bench test method using parts from vehicle’s EVAP system and other key fuel system components. The test method achieves the following objectives: first, re-create the conditions that result in excitation; second, establish a controlled environment that provides insight into the noise phenomenon; and finally, set the ground work for further studies which may lead to further noise mitigation methods. The key system parameters controlled in this method are: frequency and duty cycle of the PWM signal, liquid level inside the fuel tank and tank grade/orientation. The output data includes: EVAP system purge flow rate, pressure signal inside the EVAP system (one near the CPV and one near the FLVV) and acceleration in Z (vertical) direction on the top tank surface near the FLVV mounting location.