motorcycle cooling fan, below 35 mph

Hey ya'll new guy here. Don't know much about about electronics but I figured maybe someone here does. Anyway I'm working a new project and I require a switch that functions on several parameters. The application is a motorcycle cooling fan which I would like to switch on below 35 mph, when the cylinder head temp is above 280F, and I would like a delay off so the fan will continue to run a few minutes after the motor is turned off. Currently I am working to assemble the JayCar frequency switch https://www.jaycar.us/productView.asp?ID=KC5378&form=CAT2&SUBCAtid=965#11 this will provide my power,  and I will ground the fan circuit with a thermal bimetal snap switch https://search.digikey.com/us/en/products/B1213515AEDA0GE/317-1462-ND/1986506, thats two out of three. I assume I can use a simple time delay off relay to power the frequency switch., if so I got all the characteristics I'm looking for but thats a lot of bulk to hide on a motorcycle. Is there a better way, smaller, faster, more adjustability, can this be programmed on some kind of chip in a small, neat and sexy package? Like I said new guy here, don't have electronics background so I'll take what ever you can offer up. Thanks.

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Just swap any two wires, it should work then.

Yes - a PIC or PICAXE chip. They have analog to digital for the temp analog sensing, digital inputs for "state" sensing (on/off temp sensors, IGN) with counters (for speedo). Often it's the program size that determiines which is chosen (whether small 8-pin versions or larger).


I don't understand your frequency switch to provide power.
I would have thought a frequency switch (LM2907 or 2917 etc) for the speedo conversion.
Though I suggest no speed switch - it should solely be on temperature. Why cool when not required, and why fan a cold engine.

As I recall, my Kwaka had coolant temp, head temp and oil temp triggers. Although their intricate special (2) relay topology was IMO flawed (I replaced with 2 normal SPST relays), it was an effective system.
2 inputs only worked with ignition power, the 3rd - probably radiator coolant - operated whenever (there was no timer).   
BTW - all sensors were grounding when active, hence I could just parallel those I wanted to trigger one relay.

Remeber now, I'm electronically challenged, with my limited understanding, I figured out that my bike speed sensor is a hall effect pulse sensor, did some googling and came to the conclusion the frequency switch was what I needed. My project is a parade fan for an air-cooled motor, and not running the fan on a cold motor is precisely the reason for the multiple parameters for the switch to close. I don't want the fan on over 35 MPH and I don’t want it on when the engine is cold. The only additional feature I'm looking for is the delay off, so if the motor is hot enough to turn on the fan it will continue running after the ignition is turned off, untill it cools enough to switch back off. I could hook up my frequency switch to always hot instead of ignition hot. Where can I learn about the PIC or PICAXE you mentioned?

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Just swap any two wires, it should work then.

Google.

But I'd trigger off oil temperature and forget speed. (Air coooled really means oil-cooled - eg, old VW engines etc.)
Besides, you are really saying speed is irrelevant unless not-cold - ie, if hot.
And why fan en engine even if stationary of not needed.
One of the worst engine wearers is under-temp running.

Thanks for the input but I only need asistance with the electronics to achieve what I posted, I don't need to redesign the entire concept of my project. I'm only electronically challeneged, the rest of the skill and knowledge required to carry out my project are under control. I've already skinned the oil cooling cat, and no air-cooled doesn't really mean oil-cooled at least on my HD. There is no predictable relationship between oil temperature and cylinder head temperature, so triggering a cylinder head cooling fan off of the oil temperature would be futile. Again thanks for the lead on the PIC/PICAXE. Maybe I'll try over in the motorcycle specific section.

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Just swap any two wires, it should work then.

If you use power through the frequency switch and ground through a bimetal temp switch the fan will only come on if the bike is below 35mph AND the temp is above the setpoint. Is this what you want to do?

I would think that you would want the fans to come on, regardless of speed, if the temp is above the setpoint.

In order to shrink the package down I second oldsparks recommendation of using a microcontroller. A Pic is just one of many. Many DIY'er and hobbyists prefer the Atmel AVR to the Pic because the cost to get started with an AVR is virtually nothing (free software, $1/chip, and you can make a programmer for $3). Another good option to research would be Arduino. I know nothing about them, but they are a customizable platform based around an AVR microcontroller that has a huge support community to help with programming.

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Kevin Pierson

As per KP, definitely something programmable. Setting interdependencies gets too complicated for analog or discrete circuits.


But I suggest a rethink about the speed aspect - draw out a flow-chart or truth table for when you want the fan(s) on.
It is true that you "don't need to redesign the entire concept of your project" - you can always rebuild it later if you find its shortcomings...


My air/oil comment was merely to emphasis the importance of oil in cooling. For liquid cooled engines, oil typically accounts for 40% of the cooling. And whilst people clam old VWs are air cooled, they are not - they are oil cooled.

But while bikes perhaps tend to be less oil cooled, I'd suggest BOTH head & oil temp can trigger the cooling.
However that has an interesting problem - what if the oil is hot but the sleeves (bore jacket) is cool, or vice-versa. More so the former - cold bores are not good!    


I presume you have mods that have increased the heat from the engine. I may have lost touch, but few air-cooled engines (additional) require fans. And I have seen a few stationary HD engines without fan assist - eg, generators, wheelchairs, air-compressors.   


But I'd skip the frequency conversion - there is no need for it.
Cooling should be a function of temperature, nothing else. (Except intelligent predictive avoidance - ie, pre-cooling.)

Your engine will have an optimum operating temperature (usually for the compression chamber) and that is what you want to keep to.

You got it; below 35 MPH and  above a set temp, that is what I want to accomplish, with the bonus addition of a delay off, so the fans will contue to cool for a few munitues after the ignition is switched off. Sorry guys I left out some of the details that I didn't really feel important for the purpose of figuring out how to accomplish my desired switching function. I'm kinda using a Lean Six Sigma approach to my project, instead of using one oversized parade fan mounted between the two cylinders, I'm using two fans, precisely located for maximum effect, just big enough to move enough air do the job; since they are relatively weak, they would basically be ineffective at speeds over 30-35 MPH, so there is really no point to allow them to run when not needed. Minimum power draw on the electrical system is another goal, so maximum time off is desireable. I've already tested the prototype with just the thermal switch and it works very well, the speed/frequency switch function would make the system totaly automatic, and remove the need for me to operate a manual toggle switch as I approach and depart low speed operation situations, like routine traffic or city driving. Thanks again for the input guys, I will start looking into the options you have mentioned and try my hand at elctronics, seems like its just a different kind of fabrication.

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Just swap any two wires, it should work then.

Six Sigma will not alter the suitability of your design.

Maybe to paraphrase, why do you want the fan to come on below a certain vehicle speed?
Not that fans are required in any vehicle above typically 20-30 mph irrespective of fan power, but can you name a vehicle that has fans come on below a certain speed?

Or alternatively, what is the temp to come on above 35mph as opposed to below 35mph? (And why?)


But if you decide to use vehicle or wind speed, then the chip/s I mentioned else a PIC etc or even an Arduino will do the job (with suitable interfacing).


I hope you aren't being paid a bonus for this. (In keeping with 6-sigma LOL!)

Not sure how to clarify my goals any further but I'll give it a try.

why do you want the fan to come on below a certain vehicle speed?

Because as the bike speed slows it progressively loses its potential to sufficiently air cool naturally and the CHTs begin to quickly climb, the fan will continue to provide air cooling while the bike is stoped or moving slowly, the air being moved by the small fans to cool the cylinder heads will be over powered by the air rushing past the bike at 35 MPH, so no point leaving them run.

what is the temp to come on above 35mph as opposed to below 35mph? (And why?)

They won't come on above 35 MPH at any temp. While moving at speeds above 35 MPH the CHTs are naturally maintained within a desireable range, again the fans would be useless above 35 MPH because the wind rushing past would overpower the air which the fan is moving, and the air rushing past the bike above 35 MPH is actually doing the job of cooling. I won't need the cooling fan when the vehicle is moving fast enough to achieve sufficient air cooling.

I don't know that much about SIx Sigma either, just that the basic premise is maximizing efficiency.

Again, the prototype has already proven to perform as desired, I just need to build a switch to control it as I described previously.

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Just swap any two wires, it should work then.

Would be pretty simple with an 8 pin microcontroller.

Set up an external interrupt to read the speed pulses. Set up a digital input to monitor the temp switch and a second digital input to monitor ignition power. One digital output can power the fan(s) (through a transistorized output). Power the circuit from battery power so you can power the fans after the ignition has been shut off.

You could then write the logic to make the controller do whatever you want.

Dealing with the speed pulses is a bit challenging for a novice, but it really isn't that bad once you understand the concept. You basically will use a timer that resets every time the external interrupt is triggered. The timer will provide a "time stamp" that you can compare to a preset value. If the time stamp is longer then the preset then the time stamp is a lower value (the lower the speed the longer the pulse will be). When dealing with speed signals you'll need some code to detect when the signal is gone (ie bike not moving) to prevent overflowing the timer register and possibly getting undesired operations.

All the digital inputs and the timer to keep the fans on after ignition is shut off is typical "novice" tasks.



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Kevin Pierson

KPierson wrote:

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Would be pretty simple with an 8 pin microcontroller.

Set up an external interrupt to read the speed pulses. Set up a digital input to monitor the temp switch and a second digital input to monitor ignition power. One digital output can power the fan(s) (through a transistorized output). Power the circuit from battery power so you can power the fans after the ignition has been shut off.

You could then write the logic to make the controller do whatever you want.

Dealing with the speed pulses is a bit challenging for a novice, but it really isn't that bad once you understand the concept. You basically will use a timer that resets every time the external interrupt is triggered. The timer will provide a "time stamp" that you can compare to a preset value. If the time stamp is longer then the preset then the time stamp is a lower value (the lower the speed the longer the pulse will be). When dealing with speed signals you'll need some code to detect when the signal is gone (ie bike not moving) to prevent overflowing the timer register and possibly getting undesired operations.

All the digital inputs and the timer to keep the fans on after ignition is shut off is typical "novice" tasks.

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Cool, thanks, that invites a little confidence, I apreciate it. I'm rather persistent once I get my mind set on something. It may take a long time But I will fgure it out eventually. Once I research enough info to be comfortable with these tasks and I get the components together I may check back in for some assistance.

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Just swap any two wires, it should work then.

Any reason not to just go ahead an buy the 8 pin PICAXE starter kit? What other components will I need?

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Just swap any two wires, it should work then.

fabrik8r wrote:

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I don't know that much about Six Sigma either, just that the basic premise is maximizing efficiency.

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Classic!

Nor do most companies that I've worked with despite them "implemented" Quality, TQM, 6-sigma etc for decades. Ha - my last couldn't even version track or date their documentation (guess who recruited a former GE executive? He was probably attracted by the bonus scheme...).   

But 6 sigma is not about efficiency, it is about quality. It is IMO simply reverse engineering of Demings principles (ie, from stats and back to stats).
A key attribute of 6σ is research.


Sorry I confused the fan above 35mph.
I was thinking along the lines of why fan below 35mph if it isn't hot.
One engine desire is to reach operating temp ASAP.
Another is not to over-cool.
But your research should have uncovered that.


As for the PIC, try to estimate the number of program lines you require. That often set the minimum PIC "size".

Ok, just read a little on the PICAXE site,  and watched some Utube vids, not even close to understanding how to do what I want to do, but I do see that it is totally possible and relatively easy once I gain an understanding. I'm already thinking of ways to use this thing to do other stuff. Before I get to far along, my bike has its own CHT sensor in the front cylinder, can I tap this signal for the thermal trigger instead of using a thermal snap switch to ground like my original set up? I just see a lot more potential for custom adjustment of the on/off temps. I'm considering a possibility of adding individual temp sensors to control the front and rear cylinder fans independently. ,So will the 8 pin PICAXE still be big enough to incorporate all the elements of my switching function, if I use the OEM speed and temp signals, or if I use two independant temp sensors for each cylinder?

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Just swap any two wires, it should work then.

What type of sensor is it? What does it's output look like?

I am not familiar with PICs but a typical 8 pin AVR chip has 6 usable I/O pins and two pins for power and ground. To run the fans independently you would need:

CHT1
CHT2
VSS
Fan Out 1
Fan Out 2
Ignition

Assuming you have 6 pins available for I/O you should be able to pull it off with one chip. If your CHT is an analog voltage back you'll have to make sure you have two AD converters as well.

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Kevin Pierson