Automatic grill shutter prototype

[graydonengineering]

After a great deal of hard work, I have a working prototype for an automatic grill shutter device that fits behind the upper gill opening of my Nissan Frontier. I made a video of the device in action and am working on getting that uploaded onto youtube right now. I didn't want to post a failed project so I have waited till the later stages to share as I am now confident that it works as intended

The device is self regulating biased on air velocity. I have 2 pivoting shutter levers on precisely tuned spring that shut when air force becomes high enough. It is still in trial stages but I have a working prototype now. I have driven in temps over 100 degrees at varying speeds and so far I have not seen any increase in coolant temp over normal. Max with or without the device has been about 195 degrees F. I will use this thread to document my progress.

[Frank Lee]

But I like the grille block to be closed from start-up and at low speed when cold, to hasten warm-up...

[graydonengineering]

I could do that with a fully automated version with servo motors.. That may be the next version but I am trying to keep cost to a minimum.

[Daox]

I'd have to agree with Frank. If I'm gonna go to all the trouble of making an automated grill block I'd want it closed all the time until it absolutely needs to be open, right up just before the fan turns on.

[Diesel_Dave]

Cool! Can you post a link to the Youtube video?

In theory, yes, you would ideally want to run differently in the cold, etc. However, If you have a simple, robust, mechanical solution that is based only on air velocity, I'd say that's a big accomplishment.

[Old Tele man]

...should be an easy mod to have the shutters "open" when the fan(s) comes on the first time and then stay "open" as long as the vehicle speed is above 30-35 mph, ie:

OPEN @ fan ON

CLOSE @ <35 MPH


...what "control" inputs are you now using?

[orange4boy]

...what "control" inputs are you now using?

I believe it's mechanical. A spring opens the shutters when air speed is low and the shutters close when air speed is high.

Nice and simple, if not optimized.

[graydonengineering]

Originally Posted by Daox

I'd have to agree with Frank. If I'm gonna go to all the trouble of making an automated grill block I'd want it closed all the time until it absolutely needs to be open, right up just before the fan turns on.

If you don't need as much cooling, you could use the speed sensitive device allong with a partial grill block or even a full grill block. Having a self regulating device allows you to push the envelope a bit more. At current state, I have driven in over 100 degree temps without exceeding 190 degrees F which means I could potentally add a partial grill block to the lower grill, even under worst case desert heat conditions and maintain proper temps. I could certainly do so in the cooler half of the year and cut down to 25% open area at highway speed and 75% at low speed since the device allows full air flow at low speeds.

My desire is to set my front end up with the shutter and grill block to allow sufficient cooling under my personal worst case driving conditions and have no need to worry about it again. No electric motors or sensors to fail due to the harsh environments.

Last night I tuned the system in to work as intended; that is, the first shutter closes at around 45 to 50 and the second shuts around 60 to 65 mph. I matched my personal best mpg on the way to work this moring, even without the grill in place at 32 MPG! That is really good considering my recent averages have been around 27 without the device. I don't think I will maintain over 30 for the tank but if I could set a new pr, that would indicate the the shutter is giving me some real results.

[graydonengineering]

Originally Posted by Old Tele man

...should be an easy mod to have the shutters "open" when the fan(s) comes on the first time and then stay "open" as long as the vehicle speed is above 30-35 mph, ie:

OPEN @ fan ON

CLOSE @ <35 MPH


...what "control" inputs are you now using?

Yes, currently it is "brain dead" pure mechanical with limit switches that trip indicator lights in the cab for feedback purpose only.

I really like the idea of adding motor contolls in some ways. I could have the device shut at all times unless a certain coolant temp is exceeded. I see manny potential issues with that though. Cost would increase and relyability could be a factor. Also, it could have the potential to lag behind what is needed for the engine, always in catch-up mode trying to maintain coolant temperature after it has already increased rather than before.

I was also trying to think of a way to add an in-cab manual overide for warm up purposes. I think that would be a nice adition, especially for cool climates.

[Old Tele man]

...the necessary "logic" sequence (2-digit digital control logic) would be:

0 0 = power-on RESET
1 0 = fan(s) are on
0 1 = speed >30-35 mph
1 1 = (a) fan(s) on & (b) speed>30-35 mph

...a single OR-gate will do the job. Here's how the OR-gate control logic would output "follow" the fan & speed inputs:

0 0 = 0 = OFF, shutters are closed.
0 1 = 1 = ON, shutters are commanded to open.
1 0 = 1 = ON, shutters are commanded to open.
1 1 = 1 = ON, shutters are commanded to open.

...where the two inputs are: 0 = no voltage, and 1 = 12VDC, etc.

...or, you could even have it respond as:

0 0 = 0 = OFF, shutters are closed.
0 1 = 1 = ON, one shutter is commanded to open.
1 0 = 1 = ON, other shutter is commanded to open.
1 1 = 1 = ON, both shutters are commanded to open.