Abstract: A control system for a mixture-compressing internal combustion engine with a throttle flap valve disposed in an intake manifold and an idle channel bypassing the throttle flap valve. An additional channel, terminating downstream of the idle channel in the intake manifold, with the additional channel merely forming an air channel. A valve is provided for controlling a communication between the additional channel and the intake manifold. The valve is connected with a diaphragm a back surface of which is adapted to be exposed to the intake manifold vacuum through a line connected to the intake manifold. A three/two-way on-off valve, influenced by a control device, is disposed in the line connected to the intake manifold. The on-off valve is adapted to vent the backside of the diaphragm when the intake manifold vacuum is above an idle value during a coasting of the engine so as to enable air to be introduced into the intake manifold through the additional channel.

Abstract: An internal combustion engine driven by a gaseous fuel, with quantity regulation in a lower load range and quality regulation in an upper load range. A gas pressure regulator is provided for controlling a gas flow to an air-gas mixer, with a throttle valve actuatable by an accelerator pedal being arranged in an intake line downstream of the air-gas mixer, whereby the gas pressure regulator is movable in a closing direction through a control line, by a diaphragm by vacuum prevailing in the intake line in a vicinity of the throttle valve. A control valve, influenced by the accelerator in the quality control range, is disposed in a control line. The control line branches off the intake line upstream of the throttle valve or off the air-gas mixer. A throughput or through-flow cross section in the control valve decreases with increasing loads in a direct relationship to a position of the accelerator until the control valve closes at full load.