Another cabin air filter idea...

I recently purchased a 3d printed cabin air filter for my 4Runner. I think I paid $80 some dollars and its ok I guess, but the filter media itself is a joke in my opinion. I ordered the "activated carbon" version for odors and pollen but there is no way its stopping anything but leaves and pine needles. You can see right through it.

Anyways I got to thinking about using the one I bought as a model for drawing up my own 3d printed version in Fusion360 to adapt a better filter media. I'm not bad with CAD but what a pain, way to complicated. So I ordered some 1/4" air filter media off Amazon. You can't see through it like the one I had purchased. I think I saw a carbon or activated charcoal one available.

Squirrel cage fans are pretty much a bunch of airplane wings on end. Low pressure on the inside and high pressure on the outside. I was worried that my filter idea would stall the "wing" but it works just fine. I am running my tester now in the 4runner and I'm waiting on glue to set up before installing in the Tacoma. The blowers are slightly different with the 4runner being the larger.



I cut some strips and glued the ends together and made a "rim" to add some stability.



The hub is pretty large (too large) on my first one for the 4Runner. I reduced it to half as big on my tester for the Tacoma. At first I had it as being solid but things do fall down in from the cowling and I thought it would be best if this debris could still collect inside the cage.



These are kinda rough just to prove the concept, refining and templates to come if there are no issues.

 

I like the ingenuity and experimentation. Always worth pursuing no matter how absurd it may seem. Even the Wright brothers were told their plane would never work. Now we are going Mach 4 in the air.

Having said that......... I can't see how this would work. It looks like it would be too disruptive to the fan blades and air flow at that point and added weight would add to bearing failure sooner. Filters tend to work better with laminar flowing air.

BUT I'm no engineer and there are probably 12 laws of physics that I'm unaware of that would directly impact how this does or does not work.

 

I guess time will tell but air out the vents is about the same and there is no vibration like its out of balance. I didn't know what to expect, honestly.

 

FWIW: If you check the cabin filter and it's a mess and you don't have a spare: you can back rinse it with the kitchen sink sprayer and wash the all of the pollen and dirt away in a pinch. They aren't made of paper so they don't disintegrate.

 

I was thinking about the weight and balance concern...I've had maple helicopters and pine needles in my blower for years before I knew to even clean it out without noticing any vibration. I certainly agree it should be perfectly balanced and clean to live a long life. From what I've seen its mouse bodies and full on nests that cause problems lol. This little bit of foam "mostly" evenly distributed has to be better balanced than all that crap that collects on one side of the cage. I wonder if dirty blades cause more vibration issues than some small bit of debris (not mouse bodies). I may pop the cage off and weigh it and then weigh the foam filter, just for fun...

 

That squirrel cage blower wheel looks like mine has several times when I removed it for no air flow, except that my blower wheel was crammed full of grass as was the rest of the evaporator housing. The damned mice made their winter home in my A/C system.

Your system might work better if you had a thinner filter that won't impede air flow going thru it. If you lower the air flow, you lower the a/c effectiveness.

My 2004 Tacoma was the last year that they didn't have cabin air filters, the 2005 & newer did so. This is why mice get into the interior of my A/c system & plug it up, a small hole under the windshield cover plate allows them in. They also used to get into the air filter housing until I put a piece of stainless steel expanded screen @ the fenderwell entry point. The first time I checked the airfilter & found that they had eaten away part of the filter & left droppings inside the housing, motivated me to figure out a repair.

The fresh air intake hole needs a screen in it also, but it would require me to cut into the cab sheet metal which I won't do.

 

I'm surprised Dyson hasn't invented a centrifugal spinny cleaner thing that has a spring valve in the bottom that opens up and drops the stuff out every time you shut the vehicle off. I know they make something small kinda like that for Snorkels, what would happen if we put one under the hood below the cowl where it can drop out the debris before it gets to the filter?

 

So I had installed a new blower motor like a month ago in the Badger. I just pulled it down to install my new filter and found this lol. I'm hopeful it was a remnant shaken loose and not fresh lol.

I just got back from a short 60 mile trip out and about in the 4Runner. No issues with AC running the filter. I did remove the top donut piece from my Tacoma version. So its just a 2-1/2" wide strip of foam lining the inside of the cage.

There was a slight drop in air pressure coming out the vents, which I think is normal when running a filter vs. wide open. I could not imagine running my home hvac without a filter. I just replaced the evap core so I'm totally happy with this setup keeping it clean (or cleaner anyway). I have one more tweak to make but the improvement will be minimal I think.

One nice thing about the Tacoma vs 4Runner is that the Tacoma does not have any interior trims to be removed to remove the blower, unlike the 4Runner.

 

That would be pretty sweet. I thought about how to cut a clean access hole under the wiper cover. Looks difficult to do cleanly.