Hello all,
So, I have a Westerbeke brand generator that MUST run at 1800 RPM to produce a frequency of 60Hz. FYI - it has built-in overspeed protection which causes a shutdown, if needed.
It currently uses a mechanical governor to regulate the motor RPM via simple linkage to the carburetor. This mechanical governor fails, eventually, and cost around $800.
Load on the generator is always varying with appliances kicking on/off, so the engine speed is managed with fuel supply via the carburetor. The response needs to be fast.
My "plan" is to replace the mechanical governor by doing the following:
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Measure the motor RPM with something (recommendations appreciated). There are "teeth" on a spinning flywheel that could be picked up with a proximity sensor.
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Use PID control, on the arduino, to move the linkage to the carburetor via a servo (recommendations appreciated).
Hope someone can point me in right direction.
Thanks,
Tim
This looks like a very meaningful project. Regarding sensor for measuring RPM I'm not sure whether a proximity sensor or pure hall sensor is the best. 1800 RPM corresponds to 30 revolutions per second. How many blades is there on the fan? How about the mounting possibilities for a sensor? Using a optical, reflecting sensor and a black and white surface on the axle is one way.
Using the fanblades counting pulses sounds like useful. For Opto - measuring I would measure the time between 2 pulses.
Almost any Arduino would do. Se what replays You get and start making som test code for the measuring part.
I would think ignition pulses would be more reliable. How many engine cylinders? How many teeth on flywheel?
If you are thinking of using a hobby servo to control the throttle linkage then I reckon you need to reconsider. From what you describe the governor needs to be very active and I don't think hobby servos would survive for long.
In theory this is a very doable project but practice may be somewhat different. What are the consequences of a failure to maintain the correct RPM? Maybe the $800 is not such a bad deal?
Whatever system you choose to operate the throttle you can be certain that your system is not going to work perfectly first time. How do you propose to test your system with a range of loads, and varying loads? - during which time there will be significant variations from the required 1800 rpm.
This is the sort of project for which a spare generator would be useful for experiments.
...R
JCA34F:
I would think ignition pulses would be more reliable. How many engine cylinders? How many teeth on flywheel?
I once used the low side of the ignition coil but it called for some conditioning of the signals. Not that easy for none electronic people.
Robin2:
If you are thinking of using a hobby servo to control the throttle linkage then I reckon you need to reconsider. From what you describe the governor needs to be very active and I don't think hobby servos would survive for long.
In theory this is a very doable project but practice may be somewhat different. What are the consequences of a failure to maintain the correct RPM? Maybe the $800 is not such a bad deal?
Whatever system you choose to operate the throttle you can be certain that your system is not going to work perfectly first time. How do you propose to test your system with a range of loads, and varying loads? - during which time there will be significant variations from the required 1800 rpm.
This is the sort of project for which a spare generator would be useful for experiments.
...R
You've got a clear point!
I've received some more ideas from folks and am now starting out with a Hall Effect Sensor, specifically used to count gear teeth - ordered it today. I plan to disconnect the throttle linkage tomorrow and get a feel for both the force required and also confirm the full travel distance needed to manage the RPM's. I agree that hobby level servo not good. I am looking at better servos that can take the abuse. One recommendation was Savox, which looks pretty durable. Thanks for the input and I'm looking forward to giving this a try!
And I'm curious to read about Your progress.