Arduino controlled automatically actuated grill block

[texanidiot25]

I think he's talking about something that actuates in response to coolant temps, using a spring. Not unlike how the engine's thermostat is simply a spring that opens by expanding at a certain temp.

[wwkayaker]

Originally Posted by khafra

I know there has to be a simply engineered solution I'm missing, but how do you get a spring-loaded flap to open under low pressure and close under high pressure?

Put the spring to where it is pushing back towards the car on the top side with the bottom side being the part that swings against the air movement. I will try to draw it for you but I only have the basic keyboard functions so bare with me.

..........spring=/
................../o=fulcrum
incoming air=/ =radiator side of air dam



The springs could be mounted on the ends of the air dam and be attached by some metal to the fulcrum. Be sure to reinforce the entire thing to prevent any bending under the pressure. You will have to test different springs to find the right one that will be open at less than the speed at which you want it to be fully open. Also, the spring side of the lever will have to be covered to prevent the air pressure from pushing on it unless the entire air dam is on the incoming air side of the lever.

[backyard engineer]

when might we get an actual picture of this adjustable grill block? I'm thinking were all picturing one for ourselves, so it be nice to see one for real.

[Daox]

I am bringing this thread back from the dead of 2009.

A quick update. I did install the grill block on my 2003 Matrix. It did not open and close properly because the grill block conformed to the front grill which is curved. When you bend a hinge it doesn't like to work well anymore. It likes to snap open or shut. Being that it was made mostly from coroplast, it just bent and didn't open. I dinked around with it a little, but not enough to get it working properly.

I have long since sold the Matrix and the grill block has been sitting on my shelf since. I think about the project here and there and how I'd go about improving it (aka making it actually work) should I go about having another crack at it. The time has now come for that second crack.





This time around I've changed a few things. Mainly, the grill block must be straight and flat, and it also has to be more rigid. The flexible coroplast "frame" was a major problem. The frame is now made of aluminum angle that is bolted together. This allows everything to hinge properly and easily. Secondly, the thing was a big pain to work on while it was on the car. This new version is designed to be an insert so it can be relatively easily removed from the vehicle to be worked on. The mounting of the actuator was also an issue so it has been moved off of the grill block. It will now be mounted somewhere on the vehicle and it will actuate the grill block via a flexible pushrod. This will make mounting the actuator easier and allow it to get out of the way of water and other things.

On the electrical side of things I've decided to tap right into the coolant temperature sensor. I already have been working on a coolant temperature hack for the Prius, so I already have an arduino in the car and tapped into the coolant temp, so its already half done for me.





So, let me explain what we actually have here. Its an aluminum angle frame. The opening will be 12" wide by 4" tall. My upper grill has less area than that, and I have my lower grill blocked year round, so it should be plenty of area. The shutters are made of coroplast with a 1/8" steel rod stuck through one of the corrugation pockets. This acts as the hinging point and adds some rigidity. The steel rod is bent on the end to make a lever for the actuator to push on. The two steel rods are connected by an aluminum plate with some holes in it. Another bend could be made on the steel rods to capture that plate. Not pictured is a flexible pushrod that will attach to the aluminum plate. This will go to the electric door lock actuator so that it can push the grill block open and closed. An Arduino will be used to interpret coolant temperature and decide when to open and close the grill block. Using an H-bridge allows the Arduino to easily control the door lock actuator.

I'm very happy with the design thus far. It should prove much more robust and really doesn't cost much more at all. The aluminum angle is a couple bucks and the 1/8" rod is also very cheap. Any coroplast can be used and painted to look good even. But, I'm always open to new/other ideas.

[WesternStarSCR]

Subscribed! Cant wait to see it progress...

Looking at doing one using a 1" or 2" linear actuator next year. Aftermarket coolant fan switch from Summit Racing that uses probe stuck into radiator fins to fire time limted relays etc.

Grill Shutters, at their most basic, are merely rectangular butterfly valves, stacked (I know, obvious).

Your design lends this basic design concept to whatever sized needed. I think store bought air registers are more trouble and fiddly. Love the simple, large, modular, removeable design you got there.

As long as I can pivot some rectangular shapes around an axis, I can build grill block shutters, assuming wife has no other plans for the honey do list...

Great CAD images BTW.

[Daox]

Thanks. I have been thinking of it on and off for quite a while. I wanted to come up with something easy and cheap to make without any special tools, and scalable for whatever application. I think this fits the bill fairly well.

I started working on the block tonight. I have some 1/8" x 3/4" angle aluminum. Its not really what I wanted to use (I was thinking of 1/16" x 1/2" angle.), but it should work.






I started with cutting out the top lengths, and then the side lengths. I just used a hacksaw with a metal blade and clamped it in my vise. Make sure to use the smooth side of your reversible jaws, the jagged side will eat up the surface of the aluminum very quickly.





Then, I measured down 7/8" on each side and cut along the inside edge of the material. 7/8" ended up being more than enough, but gave me the overall length I wanted which was 4".





Using the vise, I bent each of the tabs inward.





Then, I cut the excess length off the ends. I'll cut the remaining excess off the tabs once I get farther along.





Then I did a test fit. It looks pretty good. My two side pieces are a little off. Bending is quite hard to get them the same length. But, I can shave a bit off the long one with a file and use a hammer to bend the tabs down a bit more.

[Daox]

I worked on the frame again tonight.




First I popped some holes in the side pieces. Yep, the excess tab still needs to be cut off.





Then I popped some matching holes in the top and bottom pieces. I also countersunk them so the insert should slide right into the hole that is cut for it. At this point I was glad I was using 1/8" thick aluminum vs 1/16".





Then all that was left was fitting and putting them together. In order to get things to line up I had to do a little slotting work with the drill and a bit of elbow grease. Thankfully its only aluminum so it eats through it pretty easily.





Here is the frame assembled. As you can see my camera kinda died on me at the end, but at least it got the whole frame in the image. It looks pretty good. Its not perfectly square, but I'll work that out another time by messing with the bent tabs.

[meelis11]

subscribed

[Ardent]

Might I suggest using an RC servo instead? I don't know the level of experience you have with the Arduino, but for those who may not know, servo control is very straightforward.

I'm working towards a very similar grill block, but it looks as though you are closer than me to making it a reality. I have an on-board Arduino performing other duties, and have CAN communication working in testing. I've envisioned a similar shutter, but with aluminum slats, the Arduino polling the ECU for coolant temp, and using a PID algorithm controlling the slats via an RC servo to the minimum required opening.

I'm currently using one of these servos: 125G EXI Servo B1228
with one of these for 12V to 6V conversion: Exceed RC UBEC-3A (2-6S Lipo Input)

[Daox]

A servo is a good way to go if you want to control how far the grill opens. I think others have mentioned it, perhaps not in this thread specifically.

The main benefit of using a power door lock actuator is the price. The servo deal looks to be ~$25 from your links. You can get a power door lock actuator on ebay for $4 shipped, and the h-bridge on mouser for $5 plus shipping.

NEW CAR UNIVERSAL POWER DOOR LOCK ACTUATOR MOTOR 12 volt U.S.A seller | eBay
TLE52052XK Infineon Technologies | Mouser

I happened to already have the door lock actuator, so all I needed was an h-bridge.

Options are always good though!