Patent attributes
A fuel vapor processing apparatus includes a canister housing an adsorbent material that adsorbs fuel vapor from a tank, and a valve in a passage connecting the canister and tank. When a stroke amount is within a range, the valve is closed to close the tank and a valve opening start position is learned. In the learning, the stroke amount is varied in the opening direction by repeatedly changing in the opening direction by a first stroke and maintaining for a first time period, and subsequently changing in a closing direction by a second stroke and maintaining for a second time period. The valve opening start position is determined based on the stroke amount in the second time period when the tank pressure is reduced by the predetermined value or more or in a preceding process.
