| 摘要 |
<p>A valve device is disclosed for an aeration and air evacuation pipe leading away from a motor fuel tank. In a known valve device for aerating and evacuating air from a motor fuel tank, a positive pressure valve is provided, the closing force of which is generated by a compression spring which is braced against its valve element. This closing force generally corresponds to the positive pressure value of a water column of 300 to 400 mm. Such a positive pressure valve is therefore unsuitable for aeration and air evacuation devices in which the required positive pressure value is very low, only approximately 80 mm WG for example, for safety and functional considerations, and correct functioning of the valve element of the positive pressure valve is required to be ensured even at low temperatures. The positive pressure valve of the novel valve device fulfills these requirements, in that its valve seat is provided on a downward sloping end face of a duct, and the valve element is a weight component which rests upon the valve seat exclusively by the effect of gravity. By coordinating the characteristics of duct cross-sectional area and weight of the valve element, any desired closing force can be determined to close tolerances, while it is impossible for condensate to accumulate under the valve element, and therefore for the latter to freeze fast.</p> |
