Abstract: With the increasing of vehicle population, the problem of evaporative emissions is becoming severer. Compared with stage Ⅱ systems, the onboard refueling vapor recovery (ORVR) systems have more efficiency, which is conducive to energy conservation and emission reduction. This paper reviewed the development history of onboard vapor recovery techniques to clarify the key technical problems that need to be solved urgently for developing and optimizing onboard refueling vapor recovery systems, and several typical onboard vapor recovery systems were introduced. The research status of filler pipe and carbon canister has been researched. The results indicate that the key point of filler pipe design is the liquid seal, and a reasonable control strategy of canister can reduce the influence of canister desorption on the air-fuel ratio of the engine. Also, the research status of the mathematical model of onboard vapor recovery system has been studied to understand the influencing factors and predict the evaporative emissions. In view of the difference between the operating characteristics of the hybrid electric vehicles engines and the gasoline vehicles engines, the control strategy of canister in hybrid electric vehicles has been discussed. Finally, the problems and future development trends of onboard vapor recovery techniques were summarized. The onboard vapor recovery systems need to be automated to achieve high-precision control to reduce evaporative emissions until the “zero emission” standard is met.

Key words: automotive engineering, onboard refuelling vapor recovery (ORVR), evaporative emissions model; filler pipes, carbon canisters