Membrane fuel pump for a membrane carburetor

摘要

The invention is directed to a membrane fuel pump for a membrane carburetor of an internal combustion engine. The carburetor has a pressure controller and the engine has a crankcase wherein pressure fluctuates during the operation thereof. The membrane fuel pump includes a pump membrane mounted in a housing which partitions a space of the housing into a pump chamber for receiving fuel from a fuel supply connection and a drive chamber. The drive chamber is charged with the pressure of the crankcase. A pressure connection connects the pump chamber to the pressure controller of the membrane carburetor. A bypass channel connects the pressure connection to the fuel supply connection and a valve is interposed between the pressure connection and the bypass channel. This valve is responsive to the pressure present in the pressure connection for switching the valve between a first position wherein the bypass channel is open to the pressure connection and a second position wherein the bypass channel is closed to the pressure connection.