Safety means for a differential pressure valve associated with a fuel injection apparatus

Claim 1

In a fuel injection apparatus of the type including (a) a pump for driving pressurized fuel for injection, (b) a fuel metering valve disposed downstream of said pump and having a variable flow passage section to control the fuel quantities to be injected into a power plant for combustion, the improvement comprising, A. a first differential pressure valve having 1. a first chamber, 2. channel means for introducing the metered fuel from said fuel metering valve into said first chamber; 3. a second chamber, 4. channel means for introducing pressurized fuel from upstream of said metering valve into said second chamber, 5. a flat valve seat, 6. a membrane cooperating with said flat valve seat for varying the outflow of metered fuel from said first chamber, said membrane separating said first and second chambers from one another and being moved as a function of the difference between the pressures prevailing in said first and second chambers and B. a second differential pressure valve having 1. a movable valve member, 2. means for applying the pressure in said second chamber to said movable valve member in the opening direction of said second differential pressure valve, 3. means for applying the pressure in said first chamber to said movable valve member in the closing direction of said second differential pressure valve and 4. discharge means communicating with said second chamber, said discharge means being controlled by said movable valve member.