A Swiss Gas Turbine for Road Vehicles
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THE use of gas turbines for driving road vehicles is complicated by the wide speed range required, and a power unit designed with this factor in mind is shown in patent No. 680,019. The patentee is Turbo A.G., 35, Breisacherstrasse, Basel, Switzerland.
The drawing shows the power-gas generating unit, the output of which is led to a turbine of the type rapidly becoming conventional. The generator is a six-cylindered swash-plate engine, the power output of which is devoted entirely to driving its own airpump and the usual auxiliaries.
Each power piston is extended to form a second piston of larger diameter, which acts. as an air
compressor. The air that is drawn in passes via poppet valves to the cylinder space. These valves are operated by a cam, tappet and bellcrank mechanism.
The outlet valves are located in the pistons, and are opened by the compressed air and closed by springs. They discharge via ports in the pistons and the compressed air is stored in a chamber until required. The power cylinders operate on the two-stroke cycle, and are charged by the stored air when the air inlet ports are uncovered by the piston.
The exhaust ports are positioned opposite to the inlets, sc that they are opened at the same time, and the result is to mix a large quantity of compressed air with the exhaust• gases, at the same time giving a scavenge to the cylinder. The combustion heads are each provided with an aircell and a sparking plug., The reason for the latter is not given, but it is probably to help ignite weak charges. An injection pump is mounted on top of the unit, and is driven by a vertical shaft which also drives the dynamo, waterpump and ignition distributor.
The control system is novel, in that the gas generator is governed to run at a constant speed of about 1,800 r.p.m. The turbine speed is varied by restricting the area of its inlet ports. When this area is at its largest, the developed gas pressure is low, and the power output is at a minimum. If the ports be contracted, the gas pressure builds up, more load is imposed on the generator, which then consumes more fuel. The velocity of the gas entering the turbine is increased and so more power is developed.
The patent gives drawings of the turbine employed, and fuiF details of the mechanism connecting the restricting valve with the accelerator pedal.