Auto_Shut_Down

George's Introduction

 The best of ideas are refined to absolute simplicity, our world wide DIYer group often refers to this as KISS engineering.

As readers know, the Power in Utterpower is having contact with Engineers (active and retired), and DIYers with lots of hands on experience. Gwyn Lawrence down in Belize has a high need to refine ideas to a "least cost", and due to the environment he and his neighbors live in, the solution must be rugged and reliable as well.

Some of Gwyn's conclusions brought a smile to my face, one in particular was bicycle parts. There are a few things I've designed that sent me to some of my favorites haunts, that being  the junk yard, and even dumpster diving behind transmission rebuild shops, and Tire stores.  I've even been found inside dumpsters, and had to talk quickly and let employees know I had permission from their Boss to be there :-) The Mission was all about finding the most common and appropriate donor piece to make something out of, 'Kiss' isn't just making something simple, it's making it out of something as common and inexpensive as possible, this allows others to follow you, and to find the parts to both make it and just as important REPAIR it.

With that said, Here's Gwyn's story, I receive a story at least once a month about engines lost to overheat, and no lube oil. 

The ‘David’ Automatic Shut Down System

Background

Stationary engines require an automatic shut down system.  Most commonly this is triggered by high temperature due to low coolant levels.  The largest company in the U.S. to build these devices is called ‘Murphy.’  This has become a generic name for automatic shut down systems.  Traditional Murphy systems start at around $300.

In April of 2007 I decided to design a Murphy system that would cost less than $10 in materials.  When completed I named this the ‘David’ system, a biblical reference and also the name of my father, who died recently.

Design Considerations 

The automatic shut down system must be produced for less than $10 U.S. in materials.

The automatic shut down system must be produced with materials commonly found in developing countries. (Because I live in Belize)

The automatic shut down system must be able to be fabricated using technology commonly available in developing countries.  (Because this is where the need exists.)

Construction Principles

Engines seize due to high cylinder temperatures.  The cylinder is encased in a water jacket.  When thermosyphon cooling systems are in operation, water temperature cannot be above boiling point.  So it was decided to use exhaust gas temperature as the trigger.

Experimentation was done on a ‘China’ diesel engine.  The 195 has one cylinder and a bore of 95mm.  It is a water cooled 12hp diesel engine.  Exhaust manifold temperature under a constant heavy load hovers around 550 degrees F.  Seizing temperature of the engine is above 1,000 degrees F.  If the engine could be shut down when the exhaust manifold temperature reaches around 600-650 degrees F. then there should be no engine damage.

The Governor Lever

On the 195 it is necessary to lengthen the governor lever so it extends beyond the side of the engine.  This is easily achieved by removing the engine data plate and fabricating a new lever or extending the existing one.

The Exhaust Pipe

 In stationary applications the engine should be in an engine shed.  It is therefore necessary to remove the stock exhaust and replace it with a straight pipe.  This permits the exhaust to be routed outside the confined space of the engine house.

The Linkage

After much experimentation it was discovered that a common bicycle cable was the cheapest, simplest and most reliable linkage.

Connecting the Dots

Placing a copper plate directly on the exhaust requires a special solder with a melting point of 650 degrees F.  In order to use a common solder (plumbing or electrical) I placed a copper plate a short distance above the exhaust.  This was achieved by bending a one inch by one eighth  ‘L’ of steel on the exhaust and squishing a piece of copper pipe on the top.

It takes a bit of experimentation to find the correct distance.  An ‘L’ of copper is then soldered to this. 

A bicycle cable then links this to a lever which will be pulled (by a spring) against the governor control when the solder melts.  Thus shutting down the engine.

Testing

I used a torch to heat the exhaust pipe in the vicinity of the manifold, measuring the temperature with an infra red thermometer.   This was done with the engine running.  The solder melted and the engine shuts down. 

Actuating mechanism.  The bike cable holds the lever in the ‘run’ position.  When the solder releases the bottom spring pulls the lever into the governor arm and stops the engine.

This is the dual fuel set up using the auto shut down bracket to tidy up the run of the diesel line.  Note that the tank is now remotely mounted. 

Copper solder joint attached directly to manifold with hose clamps and bike cable

The extended governor lever.  The assorted holes were for running derated at 1,400RPM

Which worked.

Steel ‘L’ clamped to exhaust pipe with a copper top and copper ‘L’ soldered to it.  Note the 2 threaded holes in the top left corner of the photo.  Very handy to bolt something into!

The electric start 195 with tank removed.  ST 5kw dog house also removed.  The piece of channel is bolted using the now redundant tank hold down bolts.  It makes an easy tidy up for the fuel and electric lines

This is probably enough detail for anyone to follow what is going on.  BUT, I am willing and able to add anything if required.  It took me 4 months to arrive at this solution.  I am sure there are other ways to do this, but this works and is cheap and reliable.  I used scrap material from around the shop, plus a bicycle cable.

The cable run is detailed below.

Cable run using a piece of flat steel attached to the air intake bolts

Cable run attached to injector hold down bolts.  A bit over engineered, but heh, the steel was available and the injector studs are long enough.

I also have a Listeroid attached to a 5kw in the same shop.  Also a permanent magnet DC arc welding generator.  It puts out 160 amps (80 amps a leg) which makes a great battery charger linked to a Xantrex (formerly Trace) C60 charge controller. It is also a good welder.

When it gets cold in the U.S. think about flying down to Cancun (really cheap) and taking the 6 hour bus ride to Corozal. Alternatively it is possible to fly to Belize City and travel 2 hours north.  It is also an easy drive from Texas. I’m pretty sure such an “educational” trip could be tax deductible.  My shop is next to the Caribbean.  Belize has the largest barrier reef in the Northern Hemisphere and the official language is English.  Plus Peter Singfield, the “slow speed Listeroid man” is 3 miles away and has all sorts of goodies for sale, imported directly from China.  I am also thinking of opening “The Caribbean Academy of Alternative Energy” and would need guest teachers!!!!!!!!

Just a thought.

Gwyn Lawrence  Corozal, Belize.  August 15, 2007  gwyn_lawrence@yahoo.com