Patent ID: 6874530

Claim:
A metering unit for metering liquid and/or gaseous educts by means of a feed pump for a fuel cell system comprising: a housing, a differential pressure valve ( 14 ) located within said housing for regulating the educt flow and having a movable member defining an upper valve chamber ( 34 ) and a lower valve chamber ( 32 ), a lead line ( 16 ) having a piston portion ( 16 a ), at least one control piston ( 12 ) reciprocally movable within said piston portion ( 16 a ), a first and a second connecting line ( 28 , 28 ′, 29 ) leading from the piston portion ( 16 a ) to the differential pressure valve ( 14 , 14 ′), said differential pressure valve ( 14 , 14 ′) having a regulatable throttling cross section ( 39 ) which can be varied automatically, as a function of a flow pressure dictated by the position of the control piston within the piston portion ( 16 a ), in order to regulate the educt flow, and at least one drain line ( 40 ) protruding into said upper valve chamber far enough that said regulatable throttling cross section ( 39 ) is created between an inlet side opening of said drain line and said movable member, further comprising a travel sensor ( 20 ) for determining the position of the control piston ( 12 ) in the lead line ( 16 ).