Engine Control 2

[RogerAS]

OK,

So I've played around with some chip programming, unlike the rockhead you've come to love. (er whatever) about thinking of my diesel engine. Something with which the analog chips might have a real  problem is reading engine RPM and making sharable information available. For a single cylinder diesel the rpm (tach) reading options are limited. I don't want the engine bogging down if I'm not around. There's no sense in building an automated system if you have to watch it like a hawk. :-) Even, or maybe because of, the "stamp" approach, the reading of RPM is important. With a "stamp" slot (ram or stack address) available to keep an eye on RPM why not use it? Diesels run at a "sweet spot" for both fuel consuption and long life output. Find the load and RPM and keep an eye on both.

Anyway, if I could use the output from a tach I could keep my AC genhead closer to that sweet 60Hz zone. Or more accurately I could "preset" the engine govenor with no load to get better fuel/watt ratio.

If I mounted two tiny, like CD laser neos, on 180° of the flywheel with some rugged fixed coils, I could get a double pulse and use a 2 cylinder tach. If I could generate the "spark" signature made for a gas engine tach it would work wouldn't it? Ok that's for me, what about gleaning input into the control chippery? Is there a means I'm not finding for reading RPM and convertng that to digital?

Pepa, the nights are getting sweet in the Ozarks, better come visit on veggie and bring me a barrel. I might use 50 gals a year! Hell boy, come compare carpenter scars with me! Unless you like whitetail deer huntn' better not come after 10/01! :-)

Hell, I could build a stator plate and machine the 14+" Kubota flywheel to accept magnets and have a single plate radial flux. Without the second disc there would be losses, but I could build an actuatted stator to control output and load. That would take the belt loss away. One could allow for cogging by placing the stator plate out away from the lines of flux until the engine was warmmed up. Now we're talking about some benefits of automation in the first place. One could even program in monthly engine assisted equalization cycles, or on a very bright/high output PV day. The possibilities are there.

I'm not out to make a commercial electronic design here. I'm just willing to do the grunt work to maybe get an open source diesel engine control that's reliable cheap and easy. Well maybe reliable and cheap would be good enough for me. Look what this site has done for homebuilt wind power!

I've got way more time than money, but I'm always broke!

[pepa]

hi Rodger, we have a six month long season down here, the deer ar as thick as flies on honey, only about i50#-200# but a lot of them. i have a trained hunting horse and a sweet little 44mag. carbine that shoots like a pistol and i have the missing thumb end and half of a big toe but all woodworkers do, don't they? come down here and i will show you some whitetails. pepa.

[ghurd]

Now that is just plain mean and vicious.

We don't have that many white tail here.

G-

[Colaman]

Have a look around a junkyard - plenty of modern cars have the sensors you need and they will (generally) run off 12V fine, or will not require power in at all.

For example:

• Hall-effect sensors for ignition mounted near the crankshaft pulley or in the distributor that pick up a little metal tab that sweeps past.
  
• Speed sensors from the back of a transmission to measure output rpm directly. They normally give out a few pulses per shaft revolution.
  
• A wheel sensor from an ABS system that's designed to give pulses from a "tone wheel" full of slots on the brake rotor.
  
  

All of these will give off pulses that can be readily shaped to operate an input in a stamp. From there it gets a little fuzzy for me on their programming, but you could increment a counter with each pulse, check total pulse count at a suitable interval (eg, 1 second) and calculate RPM from that. From that, you could adjust your governor to suit load, etc.

[commanda]

Most of the better micro-controllers have a "input capture timer". The timer is incremented off the internal clock. The external input (on change of state) loads the value into a register you can read, and resets the counter. Fairly straighforward to convert the value to rpm. Haven't played with one for many years. Might have been a 68HC11 about 10 years ago.

I've achieved the same result using a crystal oscillator/divider driving the interrupt pin. Interrupt Service Routine (ISR) increments the counter. Your tach signal drives another input, which can be a polled input pin or another interrupt. This might have been a Picaxe I did this on.

On chips like later generation Z80's, and the Rabbit (very close relative), you can set up an internal counter which counts down to zero, generates an interrupt, and reloads the counter. You could use this one ISR to increment another counter, and poll the input from the tacho.

Amanda

[pepa]

hi ghurd,roger, it gets better than that. no season limit, two per day, with a lot of anterless days and a anterless permit for two tags is ten dollars. this is a fixture i made from whitetail antlers, pepa.

[JW]

Hi Roger,

 You can get a proximity sensor from granger. Use one with 5000hz sampling rate. When I work with steam engines I need a crisp squarewave from the engine. The sensor I use is 1/4in in dia and 1 1/4in in length. I can mount this pretty easy. I use an aluminum target. its light weight and doesnt hurt balence to much. They have them in both NPN/PNP switching. I preffer NPN closing the circuit to ground, but thats just my prefference. These use 6 to 9volt dc. If the engine is 4 cycle spark ingition or diesel you can figure that, the cam will always spin half the speed of the crankshaft. I always use my sensors on the cam. If you want a P/N for the sensor I use, I can post it, would do it now, but dont have the granger catalog handy.

For the throttle interface, use a futaba servo. These are easily controlled with a PWM signal in the 6volt range.

hope this helps

JW

[JW]

JW

[elvin1949]

 Got plenty of whitetail here[9 in my front yard

this morning].West central Louisiana.

later

elvin