Exhaust gas recycling in an internal combustion engine

Claim 1

In an internal combustion engine 10 of the fuel injection type wherein a substantially constant volume of air is charged to the engine's respective combustion chambers from an air intake manifold 12, and an amount of fuel is injected from a fuel injector pump 13 into said combustion chambers to form a combustible mixture, which, upon ignition, forms an exhaust gas which is introduced to an exhaust gas conduit 18, an exhaust gas recycle circuit having a gas passage 21, 23 which communicates said exhaust gas conduit 18 with said air intake manifold 12, first valve means 22 disposed in said gas passage 21, 23 having a first valve means actuator 24 operably engaged therewith, a vacuum source 29 communicated with said first valve means actuator 24 to impose a vacuum atmosphere thereon whereby to controllably position the first valve means 22 and thereby regulate exhaust gas flow through said gas passage 21, 23, second valve means 34 communicating said first valve means actuator 24 with a source of bleed gas, a second valve means actuator 36 operably connected to said second valve means 34 to regulate the flow of bleed gas to said first valve means actuator 24, said fuel injection pump 13 having an indicator element 16 which is displaceable to a degree proportional to the fuel flow being delivered from said pump to the respective combustion chambers, and an engine speed indicator element 42 which is operable to provide a variable signal proportional to engine speed, said fuel pump indicator element 16, and said engine speed indicator 44, being respectively communicated with said second valve actuator whereby to adjust the flow of gas bleed into said first valve actuator 24.