Any general discussion around the firmware, what is does, how it does it etc.
User avatar
By cx500tc
#6111
PSIG wrote:Keep going with the rest of it. The difference in your answer is that the AC is using the target requiring control (low-side pressure data) to control the fan, and you are translating it into something related but completely different—the outlet temperature of the condenser—and trying to make an analogy. The condenser outlet temperature is a factor in the low-side pressure change. That does not mean you want to control the fan using one of the factors, instead of the control target (low-side pressure). You can't use condenser outlet temperature as an example for fan control when the system you are describing does not use it either. No fair. ;)

David
No big difference.

A/C low-side pressure is dependent upon the volume of Freon in the system, the temperature of the Freon leaving the evaporator and the efficiency of the condenser with regards to transferring heat from the Freon to atmosphere and thus influences the temperature of the Freon exiting the condenser. Not sure why that's so hard for some to understand since the ideal gas law explicitly allows for it. If that weren't true, one wouldn't be able to determine the mass of air entering an engine based on pressure and temperature, now, could they?


Your post saying that few vehicles use temp sensors in the radiator to control the fan... may I remind you 30 years of VW, Honda, Toyota, Chrysler, GM and others who do exactly that?

VW did so with the Rabbit/Golf, Polo and others such as the Dasher / Quantum / Passat and corresponding Audi vehicles.
Chrysler K chassis and similar derivatives like the Omni/Horizon, Reliant, Daytona and so on did that.
GM products like Camaro and Trans-Am, Corvette, Cavalier, Grand Prix and such did that.
Toyota Celica's, Tercel and others after the transition to FWD/AWD did that.
Honda did that starting with my motorcycle and most of the PGM-FI things that came from it.
-- Just checked and I can buy a fan switch for a 2010 Civic at my local AutoZone.

And I'd hazard the guess that most people looking to run Speeduino likely wouldn't be running it on any vehicle newer than 2000 or so.

So, to say it's not common is a HUGE stretch of the imagination, considering I just listed 5 of the top automakers in the world who have done it, and continue to do it, and have done so with most of their most popular vehicles.


With regards to your previous post and my replies to it, you convolute things much more than necessary without doing anything that otherwise counters my assertions.

Yes, running the fan based on the coolant exit temp being near the engine's safe, maximum temperature is probably a good thing, but when you've hit that point, nothing the radiator can do will cool you down, because if you did it my way, which unfortunately would either put fan control out of the ECU or otherwise burden the ECU with another sensor, the fan would've already been running if the radiator can't cut it based on ambient air flow alone.

I listed things that can cause the coolant temp leaving the engine to be above ideal, of which only a few bore any relation to the radiator and the need to run the fan. The radiator itself could be highly efficient, read as very oversized, and the temp of the coolant leaving the radiator could be equal to ambient air temp even without a fan running, which itself would be impressive, but... a highly loaded / stressed engine could raise the 70-100F coolant temp right back up to 210F or so when the coolant leaves the engine. Given that, does the fan need to run? No.

The logic behind that reasoning is self-explanatory.


To go back around to the A/C analogy....
The evaporator transfers heat from the air in the room to the Freon in the system, much like the cooling system transfers heat from the engine to the coolant. The Freon then travels over to the condenser, analogous to the radiator on a vehicle, where that heat is transferred to the atmosphere. The evaporator (engine) has no way of knowing the efficiency of the condenser (radiator) with regards to transferring heat to the atmosphere so using the temp of the Freon (coolant) exiting the evaporator (engine) isn't any indication of how efficient the condenser (radiator) is in removing heat from the Freon (coolant), and thus not relevant to when the condenser's (radiator) fan should run.


I think I mentioned previously that an automatic transmission could overheat an engine.
What's your take on that?
User avatar
By PSIG
#6137
I have tried to work with you here to discover or reveal your primary control logic; but this thread has degenerated in basis. This will again be long as I will directly quote all of your words and statements for accuracy. I will then respond to all of them directly and simply, maintaining the same points of operational principles used most commonly today, and which I started this 'conversation' with several pages ago:
cx500tc wrote: No big difference.

A/C low-side pressure is dependent upon the volume of Freon in the system, the temperature of the Freon leaving the evaporator and the efficiency of the condenser with regards to transferring heat from the Freon to atmosphere and thus influences the temperature of the Freon exiting the condenser. Not sure why that's so hard for some to understand since the ideal gas law explicitly allows for it. If that weren't true, one wouldn't be able to determine the mass of air entering an engine based on pressure and temperature, now, could they?
To the contrary, that is a HUGE difference, and a very specific basis point in this whole foray. You say 'temperature exiting the condenser', which is one of many factors in the low-side pressure. I am highlighting the actual control target and target sensor, which are both low-side pressure. To ignore the target of the control, while focusing on just one of many factors, will greatly limit or defeat any ability to achieve the goal of low-side pressure control. It is that simple. To continue by attempting to base primary control logic on a fallacy of operation, or by simple association to an unrelated fact, is yet another fallacy.

Your position (without further supportive evidence from you) is based on questionable cause, and specifically on post hoc ergo propter hoc and reduction-of-cause fallacies. Yes, you give “explanation”, but you fail to support that explanation with un-distorted facts and sound logic for your radiator-outlet-temperature-based fan control. I wish your control was useful as an alternative primary control mechanism, but without sound control logic, it is not. We can see some examples as we continue.

The entire following section is a misstatement and distortion of what I said. I did not say that sensors are not used in radiators. I responded to your statement that OEMs use them at the radiator outlet/engine inlet for fan control. This entire section is based on a false quote you attribute to me and therefore a fallacy. I will not waste time responding to something I did not say, whether the statement is otherwise true or not, and ask you to not distort my words or use them out-of-context again. Re-state the facts, using correct quotes and context, and I will happily respond. This is neither accurate nor fair:
cx500tc wrote:Your post saying that few vehicles use temp sensors in the radiator [FALSE, I said radiator outlet, the basis of your entire position] to control the fan... may I remind you 30 years of VW, Honda, Toyota, Chrysler, GM and others who do exactly that?

VW did so with the Rabbit/Golf, Polo and others such as the Dasher / Quantum / Passat and corresponding Audi vehicles.
Chrysler K chassis and similar derivatives like the Omni/Horizon, Reliant, Daytona and so on did that.
GM products like Camaro and Trans-Am, Corvette, Cavalier, Grand Prix and such did that.
Toyota Celica's, Tercel and others after the transition to FWD/AWD did that.
Honda did that starting with my motorcycle and most of the PGM-FI things that came from it.
-- Just checked and I can buy a fan switch for a 2010 Civic at my local AutoZone.
Then we have an inserted statement with no apparent qualification:
cx500tc wrote:And I'd hazard the guess that most people looking to run Speeduino likely wouldn't be running it on any vehicle newer than 2000 or so.
Why not? What's your point of newer than 2000? How does it support radiator outlet temperature fan control logic?

And this is a leftover of the misquote and fallacy above:
cx500tc wrote:So, to say it's not common is a HUGE stretch of the imagination, considering I just listed 5 of the top automakers in the world who have done it, and continue to do it, and have done so with most of their most popular vehicles.
So we can ditch that reference until you can quote it correctly, or we can leave it as supporting evidence of traditional fan control.
cx500tc wrote:With regards to your previous post and my replies to it, you convolute things much more than necessary without doing anything that otherwise counters my assertions.
If you are claiming that answers and explanations, escalating in a smorgasbord offering of three words to lengthy and fully detailed and supported are convoluted; then either you do not comprehend the most common cooling control systems at even their most basic level, or you are employing yet another logical fallacy known as Ad Ignorantiam (argument from ignorance), or “shifting the burden of proof”. It is not up to me to convince you, and I have only been acting to describe facts as they are in traditional systems—not concepts of a new method as you propose. As you are proposing a change in traditional control logic, it is up to you to provide the proof that the logic of your proposal is valid. You have not, are using a basis of erroneous information, and continue to avoid describing a valid control mechanism.

In this statement you are combining four different statements into one, so let's separate them for an attempt at clarity:
cx500tc wrote:1) Yes, running the fan based on the coolant exit temp being near the engine's safe, maximum temperature is probably a good thing,
2) but when you've hit that point, nothing the radiator can do will cool you down,
3) because if you did it my way, which unfortunately would either put fan control out of the ECU or otherwise burden the ECU with another sensor,
4) the fan would've already been running if the radiator can't cut it based on ambient air flow alone.
And to each statement: 1) Yes, that's the traditional method to keep it within the target limits.
2) Yes it can, and why the fan is also running in conventional systems before the target goes over-temp.
3) True and also true.
4) Again, the fan is also already running in conventional systems, as you described in #1. At least we're getting closer!

In the following quote, multiple statements are winding around each other, so again we separate:
cx500tc wrote:1) I listed things that can cause the coolant temp leaving the engine to be above ideal, of which only a few bore any relation to the radiator and the need to run the fan.
2) The radiator itself could be highly efficient, read as very oversized, and the temp of the coolant leaving the radiator could be equal to ambient air temp even without a fan running, which itself would be impressive, but...
3) a highly loaded / stressed engine could raise the 70-100F coolant temp right back up to 210F or so when the coolant leaves the engine.
4) Given that, does the fan need to run? No.

The logic behind that reasoning is self-explanatory.
There is no logic basis, as it ultimately describes a failed system:
1)You did, but the source of the heat does not have to be radiator-related, and all of the listed factors can be cause to run the fan as the target (engine coolant temperature) increases.
2) That's very close to possible. It is impossible to return to absolute ambient in a closed system with energy exchanges, due to inescapable minor inefficiencies; but you could get close. A boat using the water it's floating on for coolant is an example of constant and relatively cold intake coolant.
3) Absolutely not unless the system is FAILED. This is one fallacy source and cannot be used to base operational logic as it describes a FAILED system.
4) The fan is irrelevant, as the system is FAILED, and that explains the failure of your control logic. Flowing ambient 70°F to 100°F coolant into the engine, and the target engine temperature be overheating at 210°F describes a FAILED system, outside of operational norms and does not support fan control logic.

OK, ready for another total failure? Here we go, with multiple logic fallacies:
cx500tc wrote:To go back around to the A/C analogy....
The evaporator transfers heat from the air in the room to the Freon in the system, much like the cooling system transfers heat from the engine to the coolant. The Freon then travels over to the condenser, analogous to the radiator on a vehicle, where that heat is transferred to the atmosphere. The evaporator (engine) has no way of knowing the efficiency of the condenser (radiator) with regards to transferring heat to the atmosphere so using the temp of the Freon (coolant) exiting the evaporator (engine) isn't any indication of how efficient the condenser (radiator) is in removing heat from the Freon (coolant), and thus not relevant to when the condenser's (radiator) fan should run.
I won't even split this one into sections or point-out the various errors, as it leaves the single greatest source of heat completely out of the picture—the AC COMPRESSOR. It is easy to explain all kinds of systems, such as how to turn lead into gold, design a perpetual-motion machine, or turn ethanol into high energy-density fuel if we can conveniently leave some really important stuff out or switch a few words like pressure and temperature. As this description is grossly incomplete and erroneous I will not address it further.
cx500tc wrote:I think I mentioned previously that an automatic transmission could overheat an engine.
What's your take on that?
And we can finish with yet another perfect example of how heat can be added to the system, and be detected by the engine coolant temperature sensor, permitting effective traditional fan control. As the transmission cooler factor (in this case either internal to the radiator or external in-front of it) adds heat to the coolant in the radiator, the engine temperature will rise. Yes, another of those innumerable factors that raises the target's temperature, allowing radiator fan response to any of them in traditional or conventional systems.

Note I have not made any personal remarks (save for the fact they are your statements), and nothing to attack your proposal to improve primary radiator fan control using radiator outlet temperature, except that you are not actually supporting it—whether you think you are or not.

David
User avatar
By cx500tc
#6174
I keep vacillating with my replies; my apologies.
PSIG wrote:I have tried to work with you here to discover or reveal your primary control logic....
David
My opinion is you haven't worked with me at all. Instead, you've attempted to point out flaws within the logic I've provided without offering anything of your own creation which would counter or correct my flaws. I may be wrong, but you've yet to convince me of such, if you've tried.




Control logic:
Radiator fan control based on the temperature of the coolant exiting the radiator. Fan would switch on at some coolant temperature deemed necessary by the end-user and switch off when the coolant temperature is at or below some other temperature, itself below the original temperature. For instance, the fan turns on when the coolant leaving the radiator is at 185F and turns off when the coolant leaving the radiator is at 165F.
The ECU would receive notification via digital input regarding the fan's operational status, i.e. on or off.

Supplemental control over the fan can be controlled by the ECU, derived from the temperature of the coolant exiting the engine, preferably set to a temperature which indicates the engine is experiencing an excursion towards overheating temperatures, perhaps 10F above the thermostat's "fully open" rating. For instance, a 185F thermostat may trigger the fan to operate when the coolant leaving the engine is at 195F.

It is worth noting that most EFI systems sample coolant temperature ahead of the thermostat, not after the thermostat, so as to be aware of engine warm-up conditions so this must be considered and accounted for.
User avatar
By PSIG
#6177
[EDIT -- I see you changed your reply, so give me a bit to get back and consider what you've said.]

Thanks for the positive response. Okay, let's look at some typical real-world operation, so we can analyze how this works in the neighbor's car, and how a different scheme like yours could perhaps work. While my notes within your quotes are grossly oversimplifying the process and many specifics; the purpose is to get each of us on the same page so we can move forward from there:
cx500tc wrote:Alright... let's back up.

Engine starts running from cold, at idle speed.

Engine puts heat into the coolant and thermostat starts opening at around 175F, permitting coolant flow.

Ambient air temp, and thus coolant temp within the radiator is 80F. <<Alright, and effectively typical, but there is some temperature rise due to thermostat bypass in most systems. The bypass permits purging of air bubbles and for the warming coolant to travel to the thermostat to be sensed. This means a minor rise in temperature in the upper radiator hose of perhaps 20°F in your example system.>>

Coolant pump sucks 80F coolant from the radiator and puts it behind the thermostat, replacing some of the 80F coolant with 175F coolant. <<Agreed, and the thermostat is barely open (rated “cracking” temperature), so flow is very small.>>

Thermostat is now seeing 100F coolant after the coolant passes through the engine, and begins closing, cutting off flow through the radiator. <<Typically, the thermostat doesn't 'pop' open, but rather 'creeps' open. The coolant flow is so small at this point, the coolant passing through the engine reaches full temperature, exiting from the engine to the radiator above 175°F from this point onward. The warmup process is relatively slow, but the radiator coolant is rising towards the engine coolant temperature.>>

Current conditions in the radiator are conductive heat transfer between the 175F and existing 80F coolant, since the thermostat is closed, thus bringing the net coolant temp up to 120F. << The thermostat is open, and there is mixing flow. As there is little or no airflow to carry the heat away from the radiator, the radiator coolant temp continues to rise, and the engine temp with it. As it does, the thermostat (and engine coolant sensor) sense the increase, and the thermostat continues to open further to increase coolant flow and control temperature. Typical temperature differential (radiator inlet versus radiator outlet) in a warmed and stabilized system is only on the order of 5 to 25 degrees F, and due to spikes from loads or rain or whatever added factors.>>

Now what?
Once it can no longer control temperature at it's limits, and if idle heat input continues, the system exceeds limits (overheats) at 195°F (175° rating + up to 20° T-stat control range). In typical systems equipped with electric fans, the coolant sensor (whether part of the ECM or separate) indicates rising engine temperature, and the fan turns ON below the range limit. In this example system, about 185°F would be typical to prevent overheat before the fans could remove sufficient heat. The fan airflow carries the heat away from the system, reducing the radiator coolant, and consequently the engine and sensor temperature.

With typical hysteresis in the control system, the engine temperature (and sensor) cool to perhaps 180°F, and the fan shuts OFF. Without the cooling airflow but the engine still adding idle heat; the engine temperature increases again to the fan ON point of 185°F. If the conditions remain stable, the cycle repeats, and the engine temperature remains within a tight 5-10° range, and also within limits.

Now, if the engine is loaded the system becomes unstable. Or airflow increases through movement, or air temperature increases or decreases, or leaves blow onto the radiator, or 101 other things. This is where it all changes, where control limitations become potential issues, and why engine temperature has traditionally been used for control. Because we cannot know what any or all of those other factors are or might be, nor to what extent or duration; we simply watch the engine temperature for their effects, and deal with them as they actually occur. The fan responds by running when it needs to, and only as much as it needs to, in order to maintain engine temperatures within the upper and lower temperature limits.

Using this typical example of operation as the basis of primary fan control today, how can we use radiator outlet temperature to improve upon the goal of tightly-controlled and limited engine temperature? Please describe how your method can detect the various changing factors, and deal with them effectively, maintaining the engine temperature within specific limits.

David
User avatar
By cx500tc
#6178
PSIG wrote:[EDIT -- I see you changed your reply, so give me a bit to get back and consider what you've said.]
...
David
Okay.

In the mean time I'll mull over what you wrote.
User avatar
By cx500tc
#6179
So, the only way to know the radiator can cool the coolant is to measure the temperature of the coolant leaving the engine?
User avatar
By StevevanProoyen
#6180
weighing in here as we are currently implementing a system to properly PWM control both radiator and AC fans on a project vehicle (not speeduino though)

In general, older vehicles with mechanical fans relied on radiator outlet thermo switches and AC high side pressure switches to kick in an auxiliary fan when things were not quite right, the thermo switch in the radiator outlet was always set to trigger at a lower temp than the engine thermostat (say 70C if the thermostat is rated at 80C)

Early oem electric fan strategies were similarly setup with fairly crude engine temp referenced on/off/speed control and may or may not have included the radiator outlet temp switch failsafe option

modern cooling fan strategies are much more complex, and in base form (ignoring for the moment vehicle speed and AC status) reference the differential between engine outlet and radiator outlet temps

an excerpt from VW/Audi document ssp_222
Code: Select all
The actual coolant temperature values are registered at two different points in the cooling circuit and indicated to the control unit in the form of a voltage signal.
Coolant actual value 1 - directly at the coolant outlet in the coolant distributor on the engine.
Coolant actual value 2 - at the radiator before coolant discharge from the radiator.

Signal utilisation
Comparison of the coolant actual values (1) and (2) is the basis for activation of the electrical radiator fan.
so basically either could work, but both are required to accurately and efficiently form a coolant control strategy
engine temp only - not optimal
rad outlet temp only - better
both = optimal
User avatar
By PSIG
#6187
Cool. ;) Actually, I'll take your second post first, to lay the concepts before my questions:
cx500tc wrote:So, the only way to know the radiator can cool the coolant is to measure the temperature of the coolant leaving the engine?
No, the only way the system can know if it is cooling the engine properly is to measure the engine temperature, typically via the CLT sensor. Can the radiator cool the coolant enough? Well, just look at the engine temperature and you will know. Without checking against engine temp, you have no idea if it can or actually is, right? No matter what else you are doing, nor how you are doing it, the results are proof. The proof is the engine temperature. The engine temperature is the specification. The only specification. Temperature from __° to __°. That is the goal, that is the target, and therefore that is the primary. The radiator outlet temperature can be an enhancement, and can be additional data to improve control (along with other factors such as engine load and vehicle speed, PID algorithms, etc.); but they only enhance the primary control of engine temperature when trying to control engine temperature. :lol:

If there are special considerations such as the expanded-range "two temperature" system StevevanProoyen describes (which you do not use and, while cool ;) and very useful overall, does not directly apply), then again fan control can certainly be enhanced with the simple deduction that a radiator outlet temperature higher than a new and lower WOT variable engine target temperature is a failure mode, so turn the fan ON. Still, the target and primary goal are the engine temperatures specified as 1) 85° to 95°C and 2) 95°to 110°C, as measured by a typical CLT (G62) sensor. Not the radiator outlet (G83) which compares it's data to a map derived from G62. This is similar to the fail-safe mode he also mentions, using the same principle that outlet temperature higher than the engine target temperature will obviously not succeed in maintaining the engine within target range; e.g., if overheat is at 200° then the radiator outlet switch is set for perhaps 195°, as the fan should already be running to control that temperature and if it is then no harm done, but if it's not, then it runs in fail-safe to help prevent over-temp or at least extreme over-temp. Fail-safe is not the primary control. It is a fail-safe.

One more point about the VW/Audi system referenced, which is the reason you were looking for better control of your fans—reduced fan power consumption. Due to the necessity of the VAG system to drop engine temperature under higher loads and heat generation, the fans use a "Pre-control pulse duty factor (dependent on specified temperature and engine speed)" which runs the fans more often, in order to have reserve cold coolant capacity to reduce engine temperatures quickly if throttled-up. A completely different scenario than yours, with different goals, and exactly the opposite results as you are after. I addressed exactly this problem previously.

I hope you can see that all-along I have not been trying to argue against your system directly, but looking to achieve what your stated goals are, and why some control schemes would be better or worse towards that. So, with that outline (agreed or not), my questions are within your quote below:
cx500tc wrote:Control logic:
Radiator fan control based on the temperature of the coolant exiting the radiator. Fan would switch on at some coolant temperature deemed necessary by the end-user and switch off when the coolant temperature is at or below some other temperature, itself below the original temperature. For instance, the fan turns on when the coolant leaving the radiator is at 185F and turns off when the coolant leaving the radiator is at 165F. << "Some" temperature? Based on what variables? Wide-open full load? Low speed? High speed? Low airflow? >>
The ECU would receive notification via digital input regarding the fan's operational status, i.e. on or off. << Why? >>

Supplemental control over the fan can be controlled by the ECU, derived from the temperature of the coolant exiting the engine, preferably set to a temperature which indicates the engine is experiencing an excursion towards overheating temperatures, perhaps 10F above the thermostat's "fully open" rating. << 10° above fully-open is 10° above typical max temperature limit (limit of thermal flow control), and would normally describe a failure. How does this work to both minimize temperature change and prevent the overheat and failure? But wait... >> For instance, a 185F thermostat may trigger the fan to operate when the coolant leaving the engine is at 195F. << This may be the primary rift I was looking for. As describe in my earlier posts; thermostats are not rated with a "fully open" temperature, but rather an "initial opening" temperature. For example, a 185°F thermostat just barely begins to open ("cracking" temp) at 185°. The same 185-rated thermostat would be maxed-out and fully open 15° to 20° higher, or about 200° to 205°, and incapable of further temperature control. Considering the fan would also be running full-blast at this point also, the system has nothing left to control or reduce the engine temperature. The point of no return. Therefore, this is the usual reason for the upper temperature limit to be roughly the max T-stat limit, as the temperature is effectively uncontrolled above that point. Whether this changes your theories or not, at least it can be restated in same-terms to reduce confusion. >>

It is worth noting that most EFI systems sample coolant temperature ahead of the thermostat, not after the thermostat, so as to be aware of engine warm-up conditions so this must be considered and accounted for. << How is it considered, and how is it accounted-for? >>
David
By RichCreations
#6190
As describe in my earlier posts; thermostats are not rated with a "fully open" temperature, but rather an "initial opening" temperature.
It does not change your argument, (or the truth of it), but this is not always true, marine thermostats often have both initial, and fully open temp ratings...
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