motorcycle cooling fan, below 35 mph

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fabrik8r

Member - Posts: 8

Joined: October 14, 2011

Location: United States

Posted: October 14, 2011 at 2:34 PM / IP Logged

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 http://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 http://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.

Just swap any two wires, it should work then.

oldspark

Gold - Posts: 4,913

Joined: November 03, 2008

Location: Australia

Posted: October 14, 2011 at 4:43 PM / IP Logged

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.

fabrik8r

Member - Posts: 8

Joined: October 14, 2011

Location: United States

Posted: October 14, 2011 at 7:11 PM / IP Logged

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?

Just swap any two wires, it should work then.

oldspark

Gold - Posts: 4,913

Joined: November 03, 2008

Location: Australia

Posted: October 15, 2011 at 9:22 PM / IP Logged

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.

fabrik8r

Member - Posts: 8

Joined: October 14, 2011

Location: United States

Posted: October 16, 2011 at 12:35 PM / IP Logged

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.

Just swap any two wires, it should work then.

KPierson

Platinum - Posts: 3,527

This member consistently provides reliable information

Joined: April 14, 2005

Location: Ohio, United States

Posted: October 16, 2011 at 1:04 PM / IP Logged

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.

Kevin Pierson

oldspark

Gold - Posts: 4,913

Joined: November 03, 2008

Location: Australia

Posted: October 16, 2011 at 4:10 PM / IP Logged

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.

fabrik8r

Member - Posts: 8

Joined: October 14, 2011

Location: United States

Posted: October 16, 2011 at 4:59 PM / IP Logged

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.

Just swap any two wires, it should work then.

oldspark

Gold - Posts: 4,913

Joined: November 03, 2008

Location: Australia

Posted: October 16, 2011 at 5:21 PM / IP Logged

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!)

fabrik8r

Member - Posts: 8

Joined: October 14, 2011

Location: United States

Posted: October 16, 2011 at 7:19 PM / IP Logged

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.

Just swap any two wires, it should work then.

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