Thanks for the helpful list, Thingstodo!
I was thinking that a 3 phase motor might be more reliable than a brushed dc motor (to power the pump) Would you find this true? Perhaps a really simple sensorless-type controller could be used? I suppose if a 3-phase motor is used, the controller could give an "everythings working" ok signal. Also, could a **very rough** hall-effect type sensor be used for a minimal 3-phase control? I mean, theoretically, no control at all is needed, just a rotating magnetic field. If the hall effect sensor detected that the rotor wasn't turning even though the magnetic field was, then perhaps the pump is jammed?
Next to knowing if the pump is turning, a pressure gauge/switch would be pretty simple. I agree that knowing there is pressure does not mean there's flow. Example: high pressure in front of a clogged filter.
I also agree that monitoring temperature (accurately) can be pretty easy. I just got a PID controller for my espresso machine, and setting up the temperature sensor was extremely easy.
So a combination of pressure gauge an temperature sensor would be quite effective in verifying that an oil system is working. Minimum pressure at a specific point along with a maximum temperature at another point in the system would verify operation.
So, perhaps with the right monitoring and a reliable power source, and external pump would not hurt the system reliability.
- E*clipse
Quote:
Originally Posted by thingstodo
You can monitor a bunch of stuff. This list is my personal, off-the-top-of-my-head, cheap and easy order:
1 - the current used by the motor when *ACTUALLY* pumping. This is an interlock to the controller that will not allow the car to move if the pump is not working.
2 - a sensor (analog or just a switch) in the line that shows oil flow but wastes some of the pump capacity, again as an interlock to the controller
3 - measure the temperature of the part that needs cooling/lubrication and have both an alarm value and a shutdown value that again, shuts down the controller
1 - a Hall effect sensor can give a signal to a simple comparator that feeds Good/Bad to the controller; maybe $20 for OK parts.
1 - or if there is an overall car controller you can go analog and use a setpoint, and deadband, and all that good stuff. Less money if there is already a car controller and a display - maybe $10?
2 - flow switch already is Good/Bad signal, ready for the controller. Flow switches are not that reliable, but the small size means you can use hydraulic sensors. Maybe $50 or so
3 - temperature sensor would have to be non-contact. An IR sensor pointing at the part, that can be soaked in oil ... perhaps a bit of a challenge. But it is the best protection since you are detecting (likley) the highest part that needs oil, and also determining if the oil cooling is being effective. If the motor temperature is a good indication of oil circulating - that's easy to do.
I don't like flow sensing. It's great when it works, but it's a bit of a pain to calibrate. Pressure is easier to calibrate but does not show flow by itself. Temperature is awesome with RTDs and Thermocouples - no calibration! Current sensing is not very accurate, on average, but can be checked with a clamp-on meter and is close enough to give you information ... like if the pump is MOVING oil.
Just my 2 cents.
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