Still thinking about this.
Well that little boat/car engine with the electric starter looks promising. I could really use a system that works like this. --When the sub is on the surface, the gas engine (and small generator) automatically starts, unless the battery already has full enough charge. If the generator is running on the surface and the sub goes under, the snorkel closes, stopping the airflow intake and the engine shuts off. On the surface again the engine automatically starts if the battery needs charging.
It doesn't start until it detects a low battery condition and it automatically shuts off when a full charge condition is reached or the sub submerges. This could be done with a voltage sensitive solenoid shutting the flap on the snorkel float valve (closed when underwater or battery fully charged). The gas motor/generator (engine/generator one unit, no clutch) only starts when sub is on the surface and battery condition is low. If the sub is under, float flap valve closed, starter motor relay not energized. On the surface, voltage sensitive solenoid not energized, starter motor relay energized – engine starts
But how would the little electric starter motor know-how to disengage once the engine was running?
The voltage regulator on the generator could trigger a relay when detecting low-voltage, to start the little gas engine starter motor. But in the condition where the float valve is closed, power to the relay could be off. This would have to be a physical switch. Maybe even a sealed mercury switch.
This whole assembly, engine/generator, would have to be in some sort of watertight chamber.
For safety the fuel could be in a separate container. If the fuel were in some type of rubber bladder like a small balloon it would provide fuel under a pretty much constant pressure, and you wouldn't have to worry about a separate snorkel for the fuel chamber. A one-way type of valve arrangement could be used to fill the bladder with a few cc of fuel.
Exhaust gas, another flap valve to keep water out.
Well, you just need to see what I'm saying I think I know what I mean!!!!
Edited By Carcharadon on 1077756040