Engine controller update

[Jens]

Seeing that we have a brand new corner set up for automation, I guess I should take advantage of this new playground

I thought I would give a sneak preview of what I am up to.

First, I would like to go into the background a bit to give some overview of things.
As a lot of you know, I run a 20/2 to heat my house. I used to heat with wood in an airtight fireplace. The project really started when I realized that chopping wood is getting harder and harder as I age.
It seemed that using the waste heat of a diesel engine that was fed with vegetable oil would be a good way to go. In addition, I had long contemplated acquiring a backup generator and the combination of the two seemed like the Universe telling me that all my stars where lined up and pointing to my newest hobby.
Now I would like to stress that this IS a hobby. I am not off grid or anything bizarre. I live in Victoria, BC in your average suburban setting (I do not own a white picket fence though).
If I was living off grid I would have chosen a commercial generating plant but I was looking for something I could play with.
The way I approached this in my mind is in many small steps. I first thought the concept of getting a big hunk of cast iron all the way from India would be a cool experience even if the engine turned out to be a pile of scrap. Well, it was fun ..... (yup, I can scratch that off my list of things I need to do before I die).
So, I now had this hunk of cast iron and figured that making it run would be kinda cool .... boy was it ever .... Next step was to built a steel frame .... check. So then I figured that I better get this huge contraption out of the garage and my next project was borne - build a home for Thumper as I had lovingly started to call her.
About a year or so after it all started I had Thumper squirreled away in her little home and all was well. SInce I know had a working generator, it was time for the next project - the plumbing to put all this sorta free heat to good use.
Early last year I started to heat with Thumper and wouldn't you know, it worked out waaaay better than I had anticipated. I was pleased, the spousal unit finally got the idea that all this crap might be useful after all and all was well. I would run the engine for a couple of hours at night and maybe a bit in the morning. It supplied all of our heating needs and a good portion of our domestic hot water as well.
Unfortunately, it required a lot of interaction with the engine .... usually in the dark, with a flashlight and when I would have rather been horizontal, sleeping. Well, it wasn't really as bad as I am making it out but the point was that I was talking myself into a new project.
Wouldn't it be cool if everything happened automatically with only the occasional peek into the engine shed (during the day and when I wanted to play). I was also looking for an excuse to start playing with micro controllers .... and wouldn't you know, here it was 

Although I had lots of computer and electronics background, I didn't want to get involved with the additional project of building the electronics. I was looking for something off the shelf that could be customized.
After a lot of internet surfing, I finally decided to use a product called "Cubloc" from Comfile Technologies http://www.cubloc.com/product/01_03.php.
I started with a study board kit for the CB280 module. The idea was one of playing to get a feel for it all. I spent a fair bit of time programming all kinds of stuff and although the product (or the support) were nowhere near perfect, it was the best solution that seemed available. Yes, there were other outfits that produced controllers but at a considerable higher price (around 30% seems to stick in my mind) with no guarantee that they would be any better.
Time passes, I contemplate life, the stars, the Universe and then, earlier this year I did my "damn the torpedos" thing and purchased an industrial controller kit called a "CuTouch". This is not the way to save money folks ..... but remember it's a hobby. I don't drink,gamble or have to keep a string of women happy so all the money I saved was spent on this cooool controller box.
The entire kit is comprised by the actual controller, a nice touch screen, buffers and relays to control stuff in the real world. A big kid's heaven

This pretty much brings us up to speed on the entire background.

The initial goal is to control things like starting, fuel selection (diesel when cold or just before shutting down and veg oil at other times) and generally make everything happen. The automated controller will be in addition to the manual safeguards so should anything weird happen (I have been known to have made one or two programming errors in my life) the engine would not self destruct.

The controller will do the following when complete:
It will allow 'run by time' mode in which I determine how long I want to run the engine. After the appointed run time the engine will shut down.
Note that in all of these instances the controller will monitor a number of parameters and look after things like fuel selection and stuff.
Next mode is 'run by time-of-day". In this mode I specify what time the engine is to start and what time it is to stop.
The best mode, and the whole point of the exercise is the 'run by temperature" mode.
The controller gets temperature input from a number of places. The two most important inputs being coolant temperature and heat storage reservoir temperature. Heat storage from the engine is done with two 60 gallon hot water tanks inside my house. From there it is distributed for domestic hot water or heating the house.
In the 'run by temperature' mode I basically monitor the temperature in the heat storage tanks. Setup screens let me set the parameters so I can for example have the engine start when the hot water storage is down to 120F and the engine will shut of when the heat storage is at 180F. The engine will also stop if the engine coolant gets too hot or if a head overheats etc etc .....

I am hoping that before this heating season is over, the controller will be able to run the engine.

The controller monitors a large number of conditions and it is expected that it will include governor assist functions by next year. The mechanical governor has a number of issues as you all know and this electronic governor will assist the mechanical governor. The nature of thgis control is two fold - the controller will read current engine rpm and adjust as required but it will also monitor generator power draw. If, for example I switch on a 1 kw load, the controller will see this and automatically increase the throttle by a calculated amount in order to compensate for engine slow down that would normally happen. This, at least in theory,  should go a long way towards smoothing out engine RPM. The mechanical governor will  not need to adjust things because the instant the load was switched on the throttle was opened enough to keep RPM constant. Of course the same action applies when a load is removed to prevent the RPM from over-reving.

Other features which eventually will creap in are things like a fuel flow sensor. Currently the controller is set up to handle 30 temperature probes so I could for example measure coolant temperature at the input to the exhaust heat exchanger and temperature at the output of the heat exchanger. I have no idea yet what to do with all this data but the point is it will be available should I come up with some new project . Eventually the controller will be able to stream this data into a regular computer for number crunching or just for a real cool display

Temperature is acquired with Dallas one-wire temperature sensors. Current per phase will be acquired with a current transformer that will feed a Dallas one wire DAQ. I am currently stuck on a way to get enough data points of RPM measurement so that I can average the data and have reasonably quick response time to changes in speed.
Anyway, that is just one of many issues yet to be worked out.

So, this is it for now, the other humanoid units wish to interact with me for some reason or other. Feel free to ask questions and I will try my best to come up with plausible answers

Oh, one more thing - the controller will do it's best to keep engine load in a given range. If electrical power needs to be drawn for the household the controller will reduce dump loads and when power is not required the controller will dump more power (electrical hot water heaters) to keep the engine load at an acceptable level.

Jens

[mobile_bob]

Jens

excellent writeup !!

i really look forward to your progress with the cubloc product,  it should be a really nice system
when you get it up and running and look forward to reading about the projects progress.

bob g

[billswan]

Jens

Can't wait to see how all this works out.

How about a pix or two of some of the equipment........

Billswan

[veggie]

Jens,

That's really interesting. Please keep us up-to-date on the project.
Yes...pictures would be appreciated.

Two questions...
Are you programming it in ladder or BASIC?
Does that CuTouch controller have built-in relays and analogI/O ?, or do you have to buy an additional board?
http://cubloc.com/product/03_01.php

The website is quoting $399 which is quite reasonable for an all-in-one touch screen controller.

Veggie

[Halfcrazy]

Jens can you give or link to a brief description of how you are capturing the heat? Are you using a heat exchanger on the exhaust? Also do you have a thermostat in the engine?