Drop Mechanism 5

[connorg42]

Hi guys, I'm currently an Industrial designer looking at creating a product which needs a drop mechanism inside. I want the product to drop at a slow speed for about 3 feet; and then the user will pull it down slightly for it to then travel back up to its original position. would this be possible, i was also looking at whether a servo could be used to drop the product down. thanks!

 

[MikeHalloran]

So, one part of the product is hung from, uh, a skyhook.
Then, in response to some unspecified stimulus, another part of the product descends slowly for a little less than a meter, and stops.
Then the user grasps that second part and pulls it down for an unspecified distance against an unspecified force, and releases it, whereupon said second part ascends to its original position at an unspecified speed.

You just need to flesh out the specification a little bit...

Mike Halloran
Pembroke Pines, FL, USA

 

[Metalfixer]

Not sure what you need, but as a starting point, Google, 'Overhead Power and Free Conveyor'

 

[zeusfaber]

Are you trying to make a spider?

A.

 

[connorg42]

Basically im looking at using this mechanism in a battery powered smoke alarm; so once the battery is low, instead of an LED flashing, the alarm will drop so that it is in a position where it will be in the way of the the user, making them change the battery almost instantly. I am looking to have the smoke alarm and battery in the section that will drop and the drop mechanism in the part which will essentially stay on the ceiling.

 

[zeusfaber]

That sounds so irritating, it would probably work!

Using giving the thing a gentle tug to tell it to spool back up isn't an essential part of the concept. You're already sensing whether the battery is flat or not, so maybe the thing could be designed to climb back up (say) five seconds after sensing it's got a fresh battery.

Doesn't sound like the exact speed of drop or exact distance lowered are particularly critical, so for a product this size, I would have thought a small dc motor running at whatever speed comes naturally, driving a winch drum would provide adequate control. Control lowering distance using a timer, and a microswitch to sense when it's got home afterwards. If the lowering mechanism needs to know whether the battery is flat, it might be better off in the bottom half of the device.

Potential problem with that concept is that you're doing a powered lower at a time when your battery (having a dedicated suspension battery would introduce all sorts of issues of its own) is already very tired and when you want to conserve the power that's left for detecting fires.

A.

 

[IRstuff]

A typical 9V battery has its best ampacity with current draws under 2 mA, so that should be your design goal. Potentially, you might consider a ratchet or clutch mechanism for a purely gravity driven drop, so that the exhausted battery does the minimum amount of work to get the battery ejected. At 2mA, it should take about a minute to retract the battery.

The biggest challenge, I think, would be getting the battery to lay flat to keep the vertical profile low.

As an aside, many houses have much higher ceilings than 8 ft., i.e., some have standard ceilings that are 10 ft and 12 ft. Some smoke detectors are mounted on cathedral ceilings, and might be even higher than that.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529

 

[BrianPetersen]

I think the last smoke alarms I bought cost $14.99 each - or somewhere in that vicinity. What's this one going to cost?

 

[connorg42]

I am looking at having the mechanism to be as simple as possible. the motor option would be a cheap and viable design decision. Another option is for a small switch to move to allow the alarm to drop until the weight of the bottom section is acting on the wire/rope; making the alarm drop to a certain length at a gradual speed. would this generally work and is there a way to go about this? Also getting the product back up could become a problem. Looking at existing products on the market, this smoke alarm would slightly more pricey but not extortionate.

 

[dvd]

[ol 1]
[li]Equip the smoke detector with a better battery which costs less than the drop mechanism and lasts much longer.[/li]
[li]Have the smoke detector alarm sound continuously when the battery is low. That may also guarantee almost immediate change-out.[/li]
[li]In order to change the battery it is necessary to have a fresh one on hand. This is sometimes the issue.[/li]
[li]Installing a smoke detector on an overhead power-and-free conveyor might just work to lower the detector down to a workable height for battery change-out. Certainly a conversation piece.[/li]
[/ol]

 

[BrianPetersen]

5. Equip the smoke detector with a rechargeable battery and put a solar cell on the outside of it to charge it. Yeah, most of them are installed against the ceiling and won't get direct sunlight, but indirect lighting should be enough for the tiny amount of power needed.

 

[IFRs]

Gravity drop using a spring, with the latch mechanism requiring a small current to latch. When the current drops below the threshold, the latch unhooks, the spring pushes the battery down. The wires are long enough to keep the alarm functional. When the user replaces the battery, they push it upwards until it latches.

 

[IRstuff]

"Have the smoke detector alarm sound continuously when the battery is low. That may also guarantee almost immediate change-out."

The issue is that the alarm sounds tend to be high pitched, and in a house with a smoke detector in every room,it can be challenging. I'd prefer beeping with some sort of LED flashing pattern

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529

 

[btrueblood]

Just to make it even more annoying, have a motion detector circuit drop the detector when it senses somebody passing below it. Nothing gets their attention like having a 3-lb. weight bop them on the head.

 

[byrdj]

I thought the trend was to make every thing SMART. thus have it call the owner and if not addressed in due time report to the Fire Department

 

[LittleInch]

Any smoke detector now installed as part of an extension or new build in the UK now needs to be powered from the mains with a small rechargeable for power outages. This includes any others already fitted. Thus your device will slowly over time become obsolete. A bit like free standing sat navs. So many built in now sales have plummeted.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[3DDave]

Littleinch - seems like the UK electricians are going for a bonus round. While a small but noticeable extra cost to the owner, this could be hundreds of millions of pounds in windfall for electricians. The rechargeable has at best a 10 year life, and is likely to be a custom form factor to limit replacement, so another electrician will need to be hired to replace the entire fixture.

 

[rb1957]

I'm with IFRs idea ... a simple mechanical release ... a solenoid, and a bit of wire/string ... lick o'paint.

another day in paradise, or is paradise one day closer ?

 

[rb1957]

on 2nd thoughts, that'll never work ... these days you need an app ... how about that as an idea ... make a phone app that sounds if the battery level is low ... ok, that's the difficult bit, now you smart guys make it happen ... and send my royalty cheques to "Prince of Nigeria, PO Box ...

another day in paradise, or is paradise one day closer ?

 

[1gibson]

I would probably buy that if it dropped the actual battery hanging from the power wires, and when I replaced it, retracted itself.