Any general discussion around the firmware, what is does, how it does it etc.
By MoysieWRX
#825
Hi Guys,

I had some free time this evening and was a little bored, so i decided to write some code to control a cooling fan, and the code appears to be working fine on the bench (powering an LED on/off), while simulating temperature values using a potentiometer). It is optimised to present very minimal loading on the processor.

From Tuner studio you can enable the fan controls (or leave disabled if your fan is controlled somewhere else's), invert the fan output to suit your hardware, set the Fan cut-in temperature set point, set the hysteresis before the fan cuts-out again.

If this may be of interest to others I'm happy to submit the code to be merged. Let me know your thoughts
I appreciate that Josh is working on code upgrades and this may have a minor impact on his efforts.

The question then would be which spare digital pin to configure for the fan output signal on each of the board layouts?

Regards
Mike

EDIT: Attached screenshot of Fan settings menu
Attachments
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By MoysieWRX
#5754
Hi,

Yes, If i remember correctly, for whichever board mopping you are using you add "pinFan =" and then the pin number used. I've not really been getting much time on the project in the last 6 months due to other commitments, so i'm unsure if the latest code has a pin designated specifically for this purpose.

NOTE: If the pin had not been designated in the latest code, then you would need to amend this yourself at each code update.
User avatar
By cx500tc
#5784
I like the idea of CF control, but using the coolant temp leaving the engine as opposed to the temp entering the engine doesn't seem proper to me since the coolant temp leaving the engine will be thermostat rated temp or higher and not necessarily indicative of the coolant temp and radiator performance and ability to remove heat from the coolant.
By RichCreations
#5785
I like the idea of CF control, but using the coolant temp leaving the engine as opposed to the temp entering the engine doesn't seem proper to me since the coolant temp leaving the engine will be thermostat rated temp or higher and not necessarily indicative of the coolant temp and radiator performance and ability to remove heat from the coolant.
Well, it seems keeping the engine at proper temp is more important then the temp of the coolant going in, and the output tells you engine temp. I would just set the fan to come on well after thermostat opening temp, but less then "too hot" and keep the engine at the correct temp, not the radiator.
By MoysieWRX
#5800
cx500tc wrote:I like the idea of CF control, but using the coolant temp leaving the engine as opposed to the temp entering the engine doesn't seem proper to me since the coolant temp leaving the engine will be thermostat rated temp or higher and not necessarily indicative of the coolant temp and radiator performance and ability to remove heat from the coolant.
From what i understand, the use of the ECT for cooling fan control is quite common.
"* Operation of the electric cooling fan. The PCM will cycle the cooling fan on and off to regulate engine cooling using input from the coolant sensor. This job is extremely important to prevent engine overheating. Note: On some vehicles, a separate coolant sensor or fan switch may be used for the cooling fan circuit only." http://www.aa1car.com/library/coolant_sensors.htm

"On some vehicles the sensor may also be used to switch on the electric cooling fan. The data may also be used to provide readings for a coolant temperature gauge on the dashboard." https://en.wikipedia.org/wiki/Engine_co ... ure_sensor

The code however can easily be adapter to utilise an additional coolant sensor for instance. I guess there are pro's and cons to either route.

Regards
Mike
User avatar
By cx500tc
#5806
RichCreations wrote:Well, it seems keeping the engine at proper temp is more important then the temp of the coolant going in, and the output tells you engine temp. I would just set the fan to come on well after thermostat opening temp, but less then "too hot" and keep the engine at the correct temp, not the radiator.
Not entirely true. If the temp of the coolant going in isn't significantly lower than the temp of the coolant leaving, there's no real cooling going on. It's the thermostat's responsibility to maintain engine temperature, but it can't do that without "cool" coolant.

Which leads to: if the temp of the coolant leaving the engine is 240F, which is entirely possible with an engine being highly loaded, and the radiator itself can lower the temperature adequately without the fan running, for instance when moving down the road at a good clip, there's no need for the fan to run... is there?

Therefore, basing the cooling fan operation on the temperature of the coolant leaving the engine isn't necessarily necessary or even desirable.
MoysieWRX wrote:From what i understand, the use of the ECT for cooling fan control is quite common.
"* Operation of the electric cooling fan. The PCM will cycle the cooling fan on and off to regulate engine cooling using input from the coolant sensor. This job is extremely important to prevent engine overheating. Note: On some vehicles, a separate coolant sensor or fan switch may be used for the cooling fan circuit only." http://www.aa1car.com/library/coolant_sensors.htm

"On some vehicles the sensor may also be used to switch on the electric cooling fan. The data may also be used to provide readings for a coolant temperature gauge on the dashboard." https://en.wikipedia.org/wiki/Engine_co ... ure_sensor

The code however can easily be adapter to utilise an additional coolant sensor for instance. I guess there are pro's and cons to either route.

Regards
Mike
I've seen PCM control over the fan in instances where the vehicle may have air conditioning and the added load, both heat and HP draw from the compressor, may benefit from that. And, in some instances, I've seen similar from automatic transmission equipped vehicles whose ECU monitors trans fluid temps.

However, like I mentioned above in response to RichCreations, there may be instances when controlling the fan solely by the temp of the coolant leaving the engine may not be desirable.

Case in point: my motorcycle. When travelling down the road the radiator fan rarely turns on simply because there's enough airflow across the radiator to keep things cool even when under a heavy load. The fan itself presents a significant load to the electrical system, and on a bike with an already highly loaded system, having the fan not run when not needed is necessary. And I won't go too far in mentioning the fan itself only covers about 1/3 of the radiator, at most, so it really wouldn't do much were it to run when moving.

The same logic regarding airflow and electrical system load would apply to most any vehicle with an electrical fan, so basing the fan on the temp of the coolant leaving the engine isn't a good strategy, in my opinion. But I'm not against the ECU controlling the fan- just do it logically. ;)
User avatar
By PSIG
#5854
cx500tc wrote:I like the idea of CF control, but using the coolant temp leaving the engine as opposed to the temp entering the engine doesn't seem proper to me since the coolant temp leaving the engine will be thermostat rated temp or higher and not necessarily indicative of the coolant temp and radiator performance and ability to remove heat from the coolant.
Yeah, gotta go with Rich and Moysie on this one. The entire exercise is to keep the engine within a very narrow temperature range. This is generally within 15°F to 20°F (8°-11°C) of the thermostat rating, as the thermostat functions from closed to fully open in that range, and is all the capability it has to maintain temperature. The mass of the engine mirrors that temperature and is why most engines have their temperature sensors at or near the thermostat and coolant outlet. The cooling system must maintain the proper temperature range, whether it's powering a boat on a winter lake of cooling water, or in a ratty rusted truck crossing Death Valley in summer. Same temperature goals, based on coolant outlet temperature, regardless of the inlet temperature.
cx500tc wrote:If the temp of the coolant going in isn't significantly lower than the temp of the coolant leaving, there's no real cooling going on.
Correct, but that condition is reflected in the exiting temperature, whether the hot condition is caused by hot coolant entering, or if a large load is on the engine. Whatever the cause, it doesn't care, and only knows it's not enough. So to control temperatures that are escalating, the fan turns ON, increasing the heat shedding (cooling capacity) to lower the exit temperature of the coolant to within the proper range. Using your example in that process; if it was hot coolant going in as the problem, then the problem was solved right there. :D
cx500tc wrote:Which leads to: if the temp of the coolant leaving the engine is 240F, which is entirely possible with an engine being highly loaded, and the radiator itself can lower the temperature adequately without the fan running, for instance when moving down the road at a good clip, there's no need for the fan to run... is there?
Yes, there is, as it's too high if 240°F is out-of-range. "Too hot" is a relative term, based on the proper temperature range for that engine, and if it's within the range or above it. The system does not know if this was a short burst of power, or if you are still on the throttle and it's going to melt. Either way it's too high. Image If the cooling system was fully adequate, then the exit temperature of the coolant would not exceed the range. But it did. So the fan turns ON to bring it back into range as quickly as possible. Actually, the fans(s) should turn ON before it exceeds the range, in an effort to keep temperature in-control. A cooling system of sufficient capacity and proper operating condition will quickly warm to range and not exceed the range.
cx500tc wrote:Case in point: my motorcycle. When travelling down the road the radiator fan rarely turns on simply because there's enough airflow across the radiator to keep things cool even when under a heavy load.
Bingo - the exiting coolant (and therefore engine) are cool enough, and not threatening to leave the proper range, so the fan is OFF.
cx500tc wrote:The fan itself presents a significant load to the electrical system, and on a bike with an already highly loaded system, having the fan not run when not needed is necessary.
While that is not the fault of the cooling system; it is pointless to have the fan run when not necessary, and so it only runs when the exiting coolant (engine temperature) is heading out-of-range. Fortunately, that's good for your electrical system, and exactly what you're after. ;)
cx500tc wrote:And I won't go too far in mentioning the fan itself only covers about 1/3 of the radiator, at most, so it really wouldn't do much were it to run when moving.
Irrelevant, except to note that your fan being so small, it should probably turn ON sooner to allow more time to counter rising temperatures that are threatening to go out-of-range. With the point being to keep it within range, most fans will turn ON aat about half range and up, to attempt to keep it under control. If the temperatures rise above range before the fan runs, then the thermostat is out of capacity, the system is already at max flow, and the cooling air is only just starting. Too late, and a greater overheat is likely, especially if the conditions (usually high load) is still present and still pushing temps up. While unnecessary fan operation is useless, engine temperature control is critical to performance, efficiency, and engine life. If in-doubt I would run the fan too much as the safer alternative.

David
By RichCreations
#5857
As always, PSIG you really hit the nail on the head! I feel like we are all very lucky that you take the time to write such clear, well thought out responses. Thank you!

I just want to add, I have installed several AUX electric cooling fans, and the sensor/thermal switch ALWAYS goes on the thermostat outlet/radiator inlet. Every OEM system I have seen, also uses Engine Coolant Temp, not cold water return temp to control the fans... If you want to suggest doing it different then every known system, there needs to be a really good reason! And think about this, the coolant coming back from the radiator, will always be warmer then Outside Air Temp, so running the fan, will always add cooling capacity, even if slight.
cx500tc wrote:
And I won't go too far in mentioning the fan itself only covers about 1/3 of the radiator, at most, so it really wouldn't do much were it to run when moving.
And this one also needs addressed. yes, the fan covers part of the radiator, and causes aerodynamic drag, reducing air flow, blocking part of the radiator, and if it "windmills" (most do) then it is even worse as the area blocked is equal to the swept area of the blades, not the area of the blades themselves. So on the highway, running the fan can still have a positive effect, by no longer blocking part of the radiator, therefore increasing cooling capacity... ... by making the fan act like it is "not there" blockage wise... if the fan covers 1/3rd of the radiator, when not running, it likely reduces cooling capacity as much a 15-20%. The good news is, at highway speed, that fan likely pulls less current, as it is being helped by the air velocity.
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