| 摘要 |
Known tank systems have an adsorption filter in order to accept degassing constituents of the fuel in a fuel tank. Such tank systems have to be tested for leaks and a pump appliance is provided for this purpose. The pump appliance is fitted to a ventilation conduit of the adsorption filter in order to supply a defined volume to the tank system so that an increase in pressure in the tank system is effected. In order to determine whether the tank system is pressure-tight, ample time is left after the pressure build-up in order that, if pressure decays, the conclusion can be drawn that there is a leak. The pump appliance according to the invention possesses an electromagnetic valve which has a vacuum connection connected to an induction pipe of an internal combustion engine in order to adjust, alternately, vacuum and ambient pressure in a pump space so that the pressure forces move a pump diaphragm in order to pump air into a ventilation conduit of an adsorption filter. During the pump procedure, it is necessary to ventilate the electromagnetic valve and this takes place, in accordance with the invention, by means of a ventilation opening leading directly to the surroundings. The pump appliance according to the invention is provided, in particular, for a tank system of an internal combustion engine.
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