| 摘要 |
<p>A system for recovering a mixture of gasoline vapour and air from a vehicle tank during refuelling comprises a flow metering unit 22 connected to the gasoline dispensing nozzle of a station 20 for receiving the mixture as it flows from the tank and for generating electrical output signals corresponding to the volumetric flow of the mixture, and the pressure drop over the flow metering unit. The signals are sent to a control unit 28 that determines the densities of air and gasoline vapour in the mixture. A valve (40, 50) is connected to the flow metering unit, and is controlled by the control unit in response to the density of gasoline vapour in the mixture, to vary the flow of mixture from the tank. The valve is adjusted to reduce the flow of mixture in response to a drop in density of the gasoline vapour. The flow of gasoline liquid into the tank may be measured by a meter unit 18, operatively connected to the control unit, so that the valve may also be varied in response to the gasoline flow. A sample of air may be selectively introduced to the flow metering unit 22 in order that the density of air may be determined. The valve may additionally include means for selectively passing mixtures from different dispensing stations 20 (e.g. for different grades of fuel) to the flow metering unit.</p> |
