Hi Guys
I'm Gregs partner in crime in this project. Firstly a massive thank you for the interest shown in helping out with advice & suggestions, very much appreciated!
Many of you have asked for details, so Greg gave me a nudge to register here and provide them directly.
Background and detailsAs mentioned previously, it's a boat (in a couple of weeks time we'll unveil all the details) project but this is an ancillary aspect to it.
The engine in question is single cylinder diesel, direct injection, mechanical governor (for those diesel heads it's a 1995 Lister Petter
AD1C, Build 02... so Ring Gear with the optional electric starter and variable speed 1,000-3,600RPM circa 7.5HP @ 3,600RPM). Currently hooked up to an Ingersoll Rand 'Euro' Air Compressor Pump Head via belts. It has absolutely no modern features, no alternator, no electronics etc. It doesn't have a Heater Plug (this is an option, but not fitted). This is the sort of engine used on Concrete Mixers, temporary Traffic Lights, Compactors, Water Pumps etc.
This was bought to drive a Shot Blaster for the boat restoration aspect. Once that phase is done I was minded to take the Compressor Pump off and fit a GenSet (or possibly a heavy duty 24v Alternator) and fit it on the boat as a power source (battery charging etc) thereby squeezing every last drop of value out of it
The ultimate plan is to; measure the RPM, fit a Relay to the Starter circuit, add Servos to operate the Decompressor and Engine Stop. In short have the ARM based microcontroller automate/monitor it, but of course each of those one step at a time.
This small standalone simple engine becomes the proof of concept/test bed for...
Big Marine EngineWell, this is for a several months time but the main propulsion engine is a 1964 Parsons Porbeagle (a marinised Ford(son) 4D, 4 cylinder Diesel) yielding 57HP @ 2,250 RPM iirc. Again, as you may imagine from the vintage, lacking all the mod-cons). The boat has/had two of these directly attached to each of the two prop-shafts.
We're looking hard into switching from two of these directly coupled to just the one. This will then drive a Hydraulic Pump and the props will be, in turn, driven from individually controlled Hydraulic Motors.
End goalsTo remotely monitor all aspects of both the small and large engines (RPM, Start/Stop, Fuel, Oil, Temperature etc) and remote control them.
Also to measure the direction and speed of the two prop-shafts.
RPMSo, back to the original task/question 'How would i measure RPMs in a diesel engine?'.
Thoughts about using
TCRT5000L Reflective Optical Sensor with Transistor Output (and a Schmitt Trigger to smooth the output)? I see many fans of Hall Effect (and some very good reasons why being put up too). Given measuring the prop-shafts is also a consideration and standardising on a single method has advantages the IR route is certainly attractive, and IR has its supporters here too. Perhaps we need both, Hall Effect on the Engines and IR on the prop-shafts?
Cheers
Jim.