Abstract: In an internal combustion engine, in particular for a motor car, having a fuel supply for liquid fuel, in particular gasoline, and a fuel supply for gaseous fuel, in particular natural gas, at least one heat exchanger is provided between the two fuel supplies, by means of which a heat exchange is facilitated between the gaseous and the liquid fuels.

Abstract: An oral irrigating appliance wherein the pump which draws liquid from a reservoir and delivers spurts of liquid to a jet tip has a reciprocable piston which receives motion from one arm of an oscillatable two-armed armature forming part of a three-pole electromechanical oscillator connectable to a source of alternating current. The quantity of liquid which the pump delivers to the jet tip per unit of time is variable by changing the amplitude of oscillations of the armature. The pump receives liquid by way of an inlet valve whose valve element is opened by inflowing liquid when the piston performs a suction stroke, and the pump delivers liquid to the jet tip by way of an outlet valve having a valve element which is opened by liquid when the piston performs a compression stroke. The valve element of the inlet valve is closed by liquid when the piston performs a compression stroke, and the valve element of the outlet valve is closed, with a preselected delay, when the piston performs a suction stroke.