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oil level sensor

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RK NAIR

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Dear All,

Would any one have the idea of sensing the oil level ( Lubication oil in the sump ) . the obstacle iam facing is that, while the engine works this oil will be splashed by the crank shaft ,oil will be thrown to upside continuously. Is there any cost effectice solid state sensor method to do this?

Pls guide me if you have any idea.
 
Most engines use a pressure switch to detect oil level, if there is pressure in the galleys that the oil is pumped into ,there is oil..As you mentioned the oil is splashed around in the crankcase while the engine is running and determining the oil level would be difficult. One alternitave would be to check oil temperature, when an engine is low on oil the oil will run hotter than usual.. You haven't mentioned the type of engine, so we don't know if we're dealing with a lawnmower or a oceanliner...
 
Several autos (American made) that I've owned since the early 90's have had 'low oil sensors' and I think all three autos that I own now have low oil sensors. These sensors indicate low oil level, not low oil pressure and my experience is that they do it quite reliably. The level has to be very low to trigger it but is still high enough that the oil pump intake is still flooded. That's an important point - that while all the splashing is occuring the pump intake must be fully flooded or the pump will draw air and the system pressure will drop. On an older auto the oil pressure light might be the first indication of low oil pressure when you round a corner and the intake sucks air.

A number of consumer grade things like lawnmowers and portable generators are equipped with low oil switches as well. The engines will stop or just not run if the oil level is too low. I know Honda generators have been equipped this way since 1990. Note that these are splash lubricated where autos are pressurized systems.

I'd look in manuals, handbooks or just go to a parts dealer and ask to see some low oil level indicators or switches.
 
tansis said:
Liquid level sensors , many types to choose from

https://www.globalspec.com/learnmor...detectors/level_sensing/liquid_level_switches


A capacitive level sensor looks like the best choice, and circuits can be found around the web.

Cap senders are cool, but they do depend on the dielectric constant of the media. I know there are major problems with fuel sensing because alcohol has such a higher dielectric constant than gasoline that blended fuels read radically differently as the mix changes. Also, the temp of the media changes the dielectric constant significantly, including a thermistor for thermal compensation can fix this.
 
gerty said:
Most engines use a pressure switch to detect oil level, if there is pressure in the galleys that the oil is pumped into ,there is oil..As you mentioned the oil is splashed around in the crankcase while the engine is running and determining the oil level would be difficult. One alternitave would be to check oil temperature, when an engine is low on oil the oil will run hotter than usual.. You haven't mentioned the type of engine, so we don't know if we're dealing with a lawnmower or a oceanliner...

Dear Gerty,

Its a stationary diesel engine coupled to a heavy duty compressor.when oil level goes down , this sensor signal will be fed to an solid state actuator and stop the engine.this is what i need to do.But it should be a little bit precision , other wise this compressor will switch off intermittendly.
 
stevez said:
Several autos (American made) that I've owned since the early 90's have had 'low oil sensors' and I think all three autos that I own now have low oil sensors. These sensors indicate low oil level, not low oil pressure and my experience is that they do it quite reliably. The level has to be very low to trigger it but is still high enough that the oil pump intake is still flooded. That's an important point - that while all the splashing is occuring the pump intake must be fully flooded or the pump will draw air and the system pressure will drop. On an older auto the oil pressure light might be the first indication of low oil pressure when you round a corner and the intake sucks air.

A number of consumer grade things like lawnmowers and portable generators are equipped with low oil switches as well. The engines will stop or just not run if the oil level is too low. I know Honda generators have been equipped this way since 1990. Note that these are splash lubricated where autos are pressurized systems.

I'd look in manuals, handbooks or just go to a parts dealer and ask to see some low oil level indicators or switches.

Dear stevez,

Mine is also a stationary engine,like honda genset.Please let me know the system in honda with circuit.
 
If you have room in the crankcase, you can add a still well, which is basically a cylinder which only allows oil in from the bottom. You could use a small entry hole(s) to provide some lowpass filtering of the oil level. Sensing is still a problem, but this should get rid of the splash.
 
When Worthington Air Compressor was still in business they used a oil pressure switch. The switch would monitor pressure and when pressure went below approximately 7 psi the engine would shut down. It also pulled in a latching relay with indicator light (manual reset) alerting operator why it shut down. This system also kept operator from using machine when pressure was low ,even though oil level was adequate, due to worn bearings,bad oil pump etc... A oil pressure switch from a car/truck that uses a light instead of a gauge must be used, as a gauge will give an analog output.The oil pressure switch would ground the connected wire when pressure was low...
 
Firstly, the crank does not run through the oil in the pan. Too much drag and power loss. There will always be oil droplets in the crankcase air being thrown off the pressure fed bearings. The pistons rising and falling blow these droplets around the case. That is how the cylinders and all the other non-pressure fed parts are lubricated.
Cheap lawn mower engines do have an extension on the rod cap that dips into the sump oil to lubricate the bearing.
Easiest sensor is a pivoting float with magnet attached that controls a reed switch. They are readily available with threaded plug ends. You just need to weld a bung into the sump and wire it to a light or cutoff switch. You can easily make your own by inserting the reed switch inside a sealed off brass tube with a doughnut float and magnet around the outside.
You will have to add a latching circuit so once tripped it stays tripped until manually reset.
Keep in mind the dipstick markings are for a stopped motor. The pan level will decrease by the volume of the oil system when running.
 
RK Nair- sorry I don't have any info to send. I became aware of the sensor when a friend asked me to look at his brand new Honda generator - because it failed to start. A quick read of the instructions and a telltale unopened container of motor oil revealed the problem. He never put oil in. I'd contact Honda or see if manuals or parts can be identified via the internet or from a local dealer.
 
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