Automated door opener 5

[daveward]

I'm looking for a clever 12v way to open and close an access panel. Let's say the panel is18"X18"', basically a flat piece of 20 ga steel, hinged on one side. My goal is to have the opening side (opposite the hinge) move about 4" away from its rest position and stay there until triggered shut. Ideally the motion would be relatively slow and smooth, maybe like a DVD disc as it moves in and out of an automated player.

My first idea was to hook up an lever affair to a windshield wiper motor because the motor could be mounted so as to not conflict for space with what's behind the access panel. I'm thinking the motor would be strong enough to move the door and hold it open.

Any other experiences or ideas would be welcome. Thanks. Dave

 

[plasgears]

Door remains closed by spring.
Motor drives an eccentric that pushes the door open.

If security of closure is reqd, have a pin on door that follows a track on the eccentric.

 

[IRstuff]

If you use a highspeed gear motor, you'll have enough torque to drive the door and the gearing with pretty much keep the door in place.

TTFN

 

[patprimmer]

It could also be done with a solenoid and a damper to slow the action. If security is required, the first portion of the solenoid opening stroke and last portion of the closing stroke could operate a latch.

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[MintJulep]

Door window motor. Sunroof motor. Seat adjustment motor. One of the mini vans has powered hinged windows in the back.

Sounds like a trip to the scrap yard is in order.

 

[CritchAutomotive]

I would strongly advise against using an electric motor, instead use an air ram (you will require a pump and regulator) the only problem is shutting, if you require automatic shutting (generally it would be easier to push it shut) you may need to explore the spring tensions with an adjustable regulator and bleed device to get smooth operation of the air ram.

 

[daveward]

Message to CritchAutomotive: You cautioned: " I would strongly advise against using an electric motor, instead..." But you didn't indicate what it is you're trying to help me avoid...why the concern?

And yes, you're right, it would be easier to elbow the panel shut but I actually envisioned a remotely activated opening/closing. I'd really like to consider the air ram idea if the activating mechanism nearest the door panel was sized smaller than any of the electric motors that have been considered. I could easily picture a smooth/slow opening/closing action and that would be ideal. But I do have to close it remotely.

So..I've sort of asked a bundle of questions...and where would I go to see a smallish air-ram that you have in mind?

Thanks Dave

 

[Tmoose]

Bimba cylinder ?

 

[CritchAutomotive]

There was no reason for this except I have never seen it done (I assume due to refinement, mechanisms and a lump of electronic control), most automatic openers are spring loaded opening and push shut (ie ashtrays etc) but this requires precise manufacture which would be expensive and difficult to locate, I have seen air rams used widely though never actually done it myself, but this should be your best bet as you can finely tweak the motion with the regulator until it fits your requirement (am curious to exactly what you are using it for???)

Cheers to Tmoose, that site looks pretty good, here is what I can see...

http://fluid-power.globalspec.com/Industrial-Directory/miniature_rod

 

[daveward]

In response to the curiousity question, what am I using it for...? It's wasn't my intent to mislead anyone, but I thought the explanantion on my first post would be better understood if I used an access panel analogy.

But actually...if you've ever seen some of the newer Porsches you've noticed their rear airfoils erect and retract automatically depending on vehicle speed. My idea was to put a forward facing air scoop on my front engined car...where at rest the scoop would be down/closed with no opening, so no foreign material could enter. But at some point, like at ignition, the scoop would open to it's 3 or 4" open position...and be held there until the ignition was turned off, let's say. This would give the engine a better supply of in-rushing cooler air than it now gets. I've considered whether the scoop could actually be made light enough to rise and fall based on headwind , but it seems prudent that if I'm looking for cool air for my engine I'd want it regardless of vehicle speed, hence the idea of an electric motor opening it.

Anyway, the ideas that have been generated would work very well for either an access panel or a hood scoop. If it was really for an access panel I could easily picture someone in the back seat of a Suburban raeching inside the access panel to turn on or off a video disc player or rear radio...or to even hide some contraband. Naughty suburban people.

Dave

 

[MintJulep]

Might be able to do this using engine vacuum for power.

Heater/AC damper actuators perhaps?

 

[DesignOutsourcing]

If this flap is for cooling the engine, your problems (overheating) are likely to be at low speeds or when standing. If it is for aerodynamic effect you would need to decide whether you want more downforce or less drag. Drag could be used to automatically change the spoiler angle/position. If it is just for cool air into the induction system (surely you have an air filter to keep the dirt out so a movable flap is not needed?), just keep it open. If this is just to look cool, "look honey, his thingy is moving", I suggest some pop-up light actuators which are usually pneumatic (engine vacuum) or electric.