BS2 engine monitoring project

Hotpuppy

Hi,
· I'm working on a project for my sailboat.· I want to use a BS2 to gather engine data and display it on a serial LCD.· I'm going to use a BS2 proto board mounted in a custom case.· The LCD will probably be mounted in a custom case and incorporate a buzzer and maybe one or two buttons.· That part is all fairly simple.

· The reason for this project is:
1) A New set of gauges would cost over $350 to $500.· A BS2 solution should be under $250 excluding the cost of custom mounts and cases.· I can manufacture those myself with cad/cam software and my machine tools.
2) Gauges take up space and I don't have much mounting space for the data I want.
3) A BS2 digital gauge would be more cost effective and compact.

I'm having trouble with the sensor/sender interface.

For RPM's I'm considering using a hall effect or proximity sensor mounted near the harmonic balancer.· On Kubota small diesels this has an irregular shape with a cam style side and would provide a on/off pulse that could be measuered.

Ideally I would like to use standard engine temperature and pressure senders.· I'm interested in the following data:
Oil pressure
Oil temp
Coolant Temp (antifreeze)
raw water temp (seawater)

possibly exhaust temp

I'm going to use a 4x40 LCD.

It seems like most senders are resistance style and as such a resistance capacitance circuit should work..... however, I can't find any good documentation on most of the senders that describes theory of operation and data curves.·

I'm hoping someone else here will have some experience reading engine performance data with a BS2.

Thanks,
Brian

Post Edited (Hotpuppy) : 4/18/2009 3:42:36 PM GMT

P!-Ro

On regular gas engines, you can use the spark plug to complete the task, but it might be a little different with a diesel engine. I don't know anything about diesel engines, so you will have to ask someone else about the best way to find RPM on one.

As for using the BS to complete this project--I don't think it is the best choice. If you used the SX or the Propeller you could do a lot more, and easier. It would also lower your cost to some extent.

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PG

icepuck

Sounds like you're going to learn some parts counter engineering skills....
Most any single wire sensor you find that is made for a gauge(12v) will work because those work on resistance. If you have warning lights such as an oil pressure light you will have to replace it with a gauge type of sensor.
Do you have a thread gauge? If you don't, find a tool dealer and get one for SAE and metric threads.
Remove the coolant temp switch and oil pressure switch and measure the thread pitch, if you're lucky they will be the same size and thread-that's where you will start.
Next will be to find an auto parts warehouse that will let you look through their books-I recently did this at a local carquest warehouse when I was looking for a condenser for my maytag model 92 gas engine.
Do you happen to know what model kubota you have?
Some were made so you have the option of installing an external cooler, make Tee fitting, install it on the output side and put the temp sensor there.
As far as rpm goes this where it will take a little more investigating. Some diesel engines were made with a place for a magnetic probe so a service tech could have a way to read rpm. Some engines have a place machined to hold the probe and a notch. This notch could be machined into the crank pully on the front side(water pump end) of the engine or the bell housing(or flywheel) end. If that doesn't work out then try using a reflective sensor, which you will have to make but it will be just as safe for the engine as using the magnetic probe.
Adding magnets may through it out of balance and cause expensive mechanical problems later in life.
Hope this helps...
-dan

Hotpuppy

I'm not sure why a SX or Propeller would be a better choice. Care to elaborate?

As for the sensors..... I'm having trouble finding examples of how to read them with a stamp. In particular there should be a resistance curve that the sensor uses.

I plan to solve the RPM issue with a proximity sensor or hall effect sensor.

SRLM

Either the Propeller or the Basic Stamp would for this (or SX, but I've never used it). I'd go with the Propeller since you'll probably be able to wind up the project faster and you'll be able to use a prettier display. Although the 4x20 display will get the data out there, it is a little, ahem, *techie* for a classy sail boat. Mentioned in this thread are two different color LCDs. With these, you can make a nice GUI that's a little bit more friendly and classy.

Either way, the hard part of the project will probably be figuring out how to communicate with the sensors. Once you get that figured out, the microcontroller and display are just icing.

Hotpuppy

SRLM,
Thank you for the clarification. I think you are right the propeller would be a great processor. However, I already own several BS1 and BS2 units. I thought about color vs. mono and text vs. graphics. In the end I decided that readability under a wider range of conditions was more important. LCD text won that. I'm using a Scott Edwards 420 backpack based 14 pin serial LCD unit. It can display larger text. It also supports a bell. At the end of the day I decided that a small text display was more aesthetic than a large VGA panel with pretty graphics. Most of the time I don't look at the gauges. So the data needs to be there, but it isn't a central focus. One of my issues with traditional gauges is the space consumed.

Lastly, I'm a huge proponent of KISS. Keep It Simple Silly. I can always come back and upgrade later. For now you are right the issue is reading the data.


I was hoping that someone else would have some thoughts on how to extract data from a typical engine sensor. I know from past experience I can't exactly go to AutoZone and ask "Joe the parts clerk" how to build a gauge circuit. lol. they have a hard enough time selling me a belt for my boat engine.

I was trying to avoid reverse engineering this by disassembling a gauge to figure out how it works inside.

SRLM

I'd try and see if there were any unique marks on the sensors, and try and look up a datasheet.

Hotpuppy

I haven't found so much as a single datasheet for an automotive sensor... that's the headache I'm trying to unravel right now. I'm looking for just basic examples of how others are reading those sensors.

My guess is that there isn't anything magical in these and that they are just chips in brass. In which case I might make my own so I at least know what they are.

FearTurtles

All of the sensors that you are referring to work off of resistance. So you should be able to use an RCTiming circuit to determine the temps. That is nothing more then a resistor(the sensor) in series with a capacitor connected to an I/O pin. This will allow you to determine what the resistance is by measuring the time it takes the capacitor to discharge. The size of the Cap will depend on the range of the resistor. So some experimenting will be needed. Remove the sensor from the engine and place in water which is at a known temp. Say 80 degF. Measure the resistance. Then place the sensor in water that is at 200 degs and do the same. Making sure that you only submerge the part that is intended to be wet each time. Here is a link to the nuts and volts artical on RCTime circuits.

www.parallax.com/Portals/0/Downloads/docs/cols/nv/vol1/col/nv15.pdf

Larry~

Lets look at this from a different angle!

Do you own a car of the late 90 on ?

does this car have gauges or idiot lights ?

If it has gauges then by the factory repair manual for this car and it will have the info for the sensors !

Bs2 should work fine there is nothing that can't wait a couple of seconds to update.

have you laid out what your going to monitor ? can we see the list

read RPM

read OIL

read RPM

read FUEL

or

read RPM

read Oil and Fuel

read RPM

read AMPS and Volts

Read RPM