Vacuum engine

A vacuum motor, commonly known as Flame eater, one of the hot-air engines, but is in contrast to the Stirling engine is an open system. Technically, it is an atmospheric engine, since the external air pressure does the work (similar to the first petrol engine). Thus, the maximum output thrust is limited to the product of the piston area and the air pressure.

The operating noise of the engine is sucking the front of the cylinder burning flame ( outer combustion, working medium: hot air) caused and the subsequent expulsion of the cooled air. Heat is supplied through the cooling fins of the cylinder to the ambient air. Gas exchange takes place in both directions of the intake valve, wherein there are also types with separate outlet. The intake valve is usually controlled by a cam. Any existing exhaust valve opens automatically in case of overpressure. As a functional model engines, they are often built as a stationary engine in horizontal and vertical versions as well as one-, two - or multi-cylinder. They have already been used successfully in models of tractors and nostalgic in rail vehicles.

Only during the movement of the piston from the maximum displacement to mid-displacement work is done with the aid of the cooling of the flame produced by the gases pressure. For all other motions of the piston, the valve is opened.

Vacuum motors are not self starting, even multi-cylinder models do not. Similarly to the Stirling engine, a flywheel is required to overcome the dead centers.

Vacuum motor with automatic piano

There are also vacuum motors without thermal - energy conversion that use only the pressure difference from the atmosphere by means of a different type: The Reproduction Piano ( Pianola ) of the feed the paper punch card is made by a three-cylinder vacuum motor, the crank pins are at 120 degrees to always to find clear direction.