I have no idea how to design the electronics side Rindert. Those servo’s just need power applied to move and reverse polarity to move in the other direction. So if mixture is rich open the valve, if lean apply reverse polarity to adjust. If I could design the electronics I would.
Gary I believe the megasquirt will respond to your own values as opposed to an ecu programmed specifically for gasoline. So an o2 sensor, a crank sensor, temp sensor (if air cooled tap a sensor hole into head), would be all you needed for engine reference. As you mentioned, megasquirt could control your ignition as well. You might be able to manually adjust your air throttle plate initially, then let the megasquirt control an IAC valve piped into your air piping for fine adjustments during runs. IAC= Idle air control valve, usually found screwed into a throttle body. You can also pick up a tach signal from the megasquirt as well. You could probably achieve all this with the smaller “megacycle ecu”. You can plug into the megasquirt or cycle with your laptop and make changes on the fly as well as monitor current operating conditions.
Hi Jim,
The generator I am using is a Quicksilver marine generator made by Genrac. It has a Nissan MA12 engine that was fitted to Nissan Micras in Canada and Europe prior to 1992. It is a single overhead cam 1242cc motor with old school distributor ignition and a carburettor (soon to be replace with woodgas). As our power here is 50 Hertz it runs at a fixed speed of 1500 RPM.
IAC sounds promising, do you know if it is possible to use the tacho function to control engine speed rather than using a mechanical governor?
The mega, let’s just call it mega from here out, can control your idle in different way’s. A servo hooked up to a main throttle plate might be easiest. The mega would use the tach signal for reference and your programmed input as to idle speed desired, then adjust the throttle plate in accordance. I would also consider letting mega control your ignition as well. You can achieve any timing you desired at any given rpm, in other words, you can map your ignition events linear to your rpm and air/fuel needs. Are you planning to run at a constant speed and load? This is recommended for stationary motors.
You could also apply the mega towards your gasifier. Using hopper temp to activate a grate shaker for instance.
I found this DC Motor Contol circuit. I think I should be able to connect the Oxygen Sensor in where the variable resistor R2 is.
It looks like it will cost less than ten dollars to build, not including the oxygen sensor and electric choke control which I plan to get from the junkyard.
I can allready imagine how I am going to bench test this. I’ll uses a candle burning inside an oil lamp chimney to simulate exhaust.
Hi GaryH and JimR
Now this starting to sound realistically doable.
Use off the shelf hardwares. Use developed controls systems.
Bluntly said with no offence intended you biggest development impediments are you neither have actual woodgas engine powering experience. MattR so far resoponding here has. Try and keep him involved.
This part of it will not be me because I know too well now automation on a personal use gasifer power system is completely unessary. Hundreds of hours operating. Many other independently doing this now with NO automation at all. If you can clean burn in a heating woodstove, or cook/bake in a wood fueled cookingstove you can easily woodgasifer operate for home engine power.
MattR now having operated powered knows this too and that automation is to allow for more less willng to learn and be involved operators, and to expand the gasifer useage to fuels outside of actual easy woods into difficult Urban and Ag wastes streams.
JimR I can hear you have been doing your background reading. Good man.
Hopper temperature is a refueling trigger point. Many refernces to this.
For grate shaking use a pressure differential between the hopper pressure and the post grate area. MK and DJ and others.
You betcha’ use a variable engine loaded RPM as a signal for ignition timing control. Much more relaible than an engine exhaust O2 signal. Unfortuantly proprietary experience in this - I cannot name cite.
Wanna play with O2’s? Put that in the pre-cooled hot gasifier output gasses output stream. LEARN what your system/fuels/and loads will output as optimum normal remaining O2 and use that as an amplified control. never been done yet. Your contol point imput will be good but cto ciontrol what? CO/CO2 % balance iS critical important and would be Much better to monitor here but very expensive to do.
You Can use a direct hearth core temerature control point monitor - only SeanF seems to have devleoped long term reliable sensor for that. Or again with manual operations experience on your own system use a much easier farther downstream temperature control point like MikeL and others like WayneK does. Change Anything on the system and you have to then reset the calibration point doing it that way.
JimW is insn’t that many of us are afraid of electronics. Many of us with decades/whole lifetimes now using them now as working tools wnen they are beneficial to us. When not beneficial as a working tool then they are to us a distracting expense.
Hobbies are hobbies. Some people take great pleasure in making fishing lures too. When I fish it has been the fish in the fry pan that counts. I do not need to know how to make the actual lure to get this done. Just how to tie it on, use it and change out when it isn’t producing.
Now get me started on ammunition hand reloading - whole different story! Fun, fun, fun. With a real serious bite you hard capabilty. Ha! Ha! And even old codger me just switched from a non-electronic/no-electric needed beam scale to a new battery digetal. Ha! Fits in my pocket and is tranportable. Beam scale now has an honored under a dust cover resting place for when the day will come that the digetal dies as they alway do. I learned this clear back to my original RICHO pocket printing digital calulator from 1977 and 1980 Radio Shack programable pocket phone dialer along with two didferent 1970’s and 1980’s full line and pharagraph correctable digital daisy wheel typewrighters. None lasted functionable past 18-24 months. Ha! Wifes IBM Selectronic (electro-mecahnical) hard impact Ball machine can still be powered up for those rare now 4-5 page Gov’Mint forms. And she made a Timex watch last for 22 years. She made her expensive Filter Queen last for 30 years and still uses the canister base for spot cleaning and will NOT give it up for a gasifer blower no how much I whine and cry and offfer to buy her “new”, “better”.
Regards
Steve Unruh
Hi Steve,
You are quite correct in saying that I am at the hobby level. I’m an amature. I LIKE doing this. Any one who really wants to make money in the woodgas business should probably hire a contol systems engineer.
Best,
Rindert Wesseling
Yes I too am an amateur, my reasons for look at auto mixture control?
I quote from this topic…
Matt Ryder
“actually I have a controls engineer working on an engine management system for our turnkey systems. This will use the O2 sensor as it main input but also temps in the reduction zone and vacuum pressure. This system will have servo controlled valves to fine tune things. Its a ways off yet but are working on it.”
Wayne Keith
" Gary , Just read your post again . ( woodgas generator ) Yes auto control for a fuel / air would be important."
Pete Stanaitis
“I want the A/F ratio info to tell me BEFORE my engine governor opens up all the way that something is changing.”
In numerous other posts I have seen where people need to adjust their mixture, this is fine for a vehicle. However I am building a generator that will need to run for up to 6 hours at a time unattended. This is to provide AC power to the house and charge a large battery bank (2000 AH 24 volt). This is in addition to solar power, the generator will not need to be used in fine weather conditions. However during the wet season we can get many weeks of thick cloud cover and the generator will be needed then. I also have a diesel generator that that can be started and be producing power within 10 seconds. This diesel generator will auto start if the battery voltage gets too low and shut down when full charge is reached. I will run the diesel on biodiesel but I only can get a limited supply of oil to run it. Wood gas will save having to buy diesel for many reasons such as saving money, using renewable energy and most important to me not having to rely on the grid.
As for the point about low fuel, the system I am building uses an auger to feed wood chips into the reactor on demand. If this auger runs for too long indicating a lack of fuel to feed or a blockage it will trigger a shut down. Normal shut down will involve turning off the auger for a set time prior to the engine being turned off.
Hi Jim,
As this is a fixed speed generator is there any reason to vary ignition timing?
Hi Rindert,
It will be good to see how your oil lamp test goes.
I finally got the electric choke element in the mail. Here I am testing it with a 9 volt battery. It draws 1.2 Amps at first. Then as it heats up it seems to stabilize around .42 Amps. The battery didn’t get hot. The coil moved about 80° from where it started. This looks good to me so far.
Won’t this bimetal heater’s response be too slow? And, since you say that the current changes as it heats up, I think you’d need a pretty fancy algorithm to put/keep it where you want it. I don’t think (correct me if I am wrong) this device is designed to MAINTAIN any other position than either wide open or fully closed.
Pete Stanaitis
>Won’t this bimetal heater’s response be too slow?
Does the composition of the gas change quickly? How quickly?
>pretty fancy algorithm
I don’t plan to use an algorythm. This is a FEEDBACK control system.
>device is designed to MAINTAIN any other position than either wide open or fully closed.
Yes this device probably WAS DESIGNED to maintain an either open or closed position. But it is a simple resistance heater. I am fairly certain it will maintain any intermediate position I ask it to.
Anywho, if it doesn’t end up working, there ARE other actuators that I think will work as drop in replacements. 1) D’Arsonval Movement 2) Muscle Wire.
Here’s a sketch of an actuated valve I’ve been playing with, using a hobby servo, a fender washer, a piece of wire and a cake decorating thimble:
Plan on mounting it in a tee fitting to keep the servo out of the flow.
http://jamclasses.drbanjo.com/static/dimages/linear%20air%20mixture%20valve%20idea.JPG
And, more importantly, a few pics of the (work in progress) gasifier/engine monitoring system that has found its way on and off my workbench over the last few years. I have a short attention span and bounce between several projects, a trait I’m not proud of!
Is there a reason for that design, just I see it will have to work against the flow of gas and needs a much larger diameter. I am planning to use a butterfly from a EFI car manifold.
The primary reason was for tight shutoff versus a homemade butterfly. Your choice of an EFI butterfly makes more sense, as it should also give a tight shutoff.
As it is to control mixture it never needs to shut off, just control flow to get the mixture right.
True, except when its time to shut down.
I have found a way that some one else has done this, not for wood gas but it would work the same anyway. http://www.youtube.com/watch?v=TC-577J4ICo The Arduino used to control this only cost around $15 then the sensors need to be added. I see someone else has used it here http://www.hayriv.com/arduino/gasifier-monitor to monitor Gasifier temperatures and vacuums. It could be used to operate a grate shaker when the difference in vacuum changes to set level above and below the grate.
Anyway I am looking for as much info as I can online for this, especially for the mixture control. The Arduino can easily control a stepper motor connected to a butterfly valve to regulate mixture. Also I am looking at using to regulate the generator speed by sensing the AC Hertz and using a stepper motor connected to the throttle body to keep the speed correct. This would be useful for anyone wanting to use a car engine to drive a generator rather a belt driven governor like I have ATM which just does not do the job as well as I would like.
Here is list of possible options as I see it.
Monitor temperatures
Monitor vacuum
Control grate shaker
Air Mixture control
Engine speed control
It could even be used to automate the gasifier start up by pumping in diesel, igniting it, control valves as needed as temperatures come up and starting the engine when gas quality is correct. This may be a bit ambititous but as I see it is possible. If anyone thinks this is over kill or uneccecary it would be appreciated if you do not try to kill the thread. Any one with useful contributions would be appreciated.