Latching solenoid lock?

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swervyn

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Hello all

I am trying to find a suitable lock for a project I have on the go.

Basically I have a door on each floor of a 2 storey house. A lifting platform services the 2 floors.

For safety reasons I would like each door (top and bottom) to remain locked when the platform is not on that floor. When the platform arrives at the floor the lock will disengage and provide access. The lock at the other floor remains locked.

I feel I can do this quite easily with a solenoid lock but from what I can gather it means either one or the other lock will always be powered unless I can use a latching solenoid lock that activates/deactivates on pulse input then remains in unpowered state until again activated.

This is the type of lock I need:

LOCK

it has a good throw (30mm) but it (from what I can gather) will mean either the upper or lower lock will remain continuously powered. I dont know about power consumption just that I would rather it was not using it until needed!

Searching & searching for latching solenoid locks hasn't really brought me any joy but I have considered a 12V auto car unlocking device?

I have 12v power supply for the locks and wondering if there are better options available?

Thanks
 
Why not do it with a spring and an L bracket (all mechanical). The L bracket is at the top of the door holding it closed, then a small projection on the elevator car pulls the L bracket off the top of the door as the car arrives at each floor. Easy in your case since you arrive at each floor from only one direction.
 


If you want to go electric. Leave booth floors locked and only allow an "unlock" button to open the door when the car is on that floor (a switch "AND" gate). That way, you can leave power off until someone wants to open the door.

I would also check (electric interlocks) that both doors are closed before moving the car.
 
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You could use the yale type door release that will only operate if the lift is present.

You will also need to be able to check if the door is closed before the lift is able to move.

Mike.
 

Thanks, unfortunately a mechanical lock wont do the job, the doors top and bottom will actually be bi-fold doors due to space limitations so was planning (hoping) to use a pin type setup that locks down in to the top of the door leaf, this is where the 30mm throw of the one I linked would be helpful.


Pommie said:
You could use the yale type door release that will only operate if the lift is present.

You will also need to be able to check if the door is closed before the lift is able to move.

Mike.
Click to expand...


Yes, the plan is that the lift cannot operate unless both doors are in the shut position. I currently have a call button up and downstairs which I need to be able to disable when the doors are open. Currently someone could be in the process of loading upstairs and someone downstairs can call the lift which is what I need to sort out.

This is why I am thinking the electronic option



Yes, the door lock actuator is what I looked into, and it's cheap!
 
You can get motor-operated electric deadbolts as well as simple solenoid types.
I have one in a junk box - the bolt movement is progressive rather than going with a "clunk" like a solenoid.

The one I have looks like these, though with a different name on it. The have an internal switch to sense the bolt position.
**broken link removed**
**broken link removed**

They are normally spring loaded so they auto return to one state, but I see no reason you could not remove the spring and use a timer in conjunction with the internal switch to control operation each way but running the motor in the appropriate direction..
 

They look interesting too but it seems they will also always be powered in one state (either open or closed). Depending on what floor the lift carriage is on, one lock will always be open and other closed and vice versa.

I have been looking at this : Latching solenoid lock and the description looks good. They also look expensive.

Seems they have permanent magnets at each end which energises via a pulse signal, meaning they will hold either open or closed without using power continuously. I am not sure how well "normal" solenoid locks like the one I linked earlier: HERE , handle continuous voltage or what the power consumption is. From what I have read they can generate quite a bit of heat when continuously powered and I am not sure whether the should even be used in this way.

I have limit switches set up at each floor which stops the carriage at the right place, plus over travel limits switches connected to 240V which kills power should the other ones or the board they are connected to fail.

Details on long going project at this thread : HERE
 
alec_t said:
How about this?
View attachment 114557
Click to expand...
Thanks for the suggestion, I will get something drawn up to try and show my predicament. I can see what you have shown will lock the top door when the platform lowers, not sure how to go about locking/unlocking the lower door though. I also need to be able to disable the ability to "call" the platform from either floor if either door is open
 
Thanks for suggestions but manual latching really is not going to work how I want it to

Ok, so I got 2 x car door unlockers, these ones HERE

Im pretty sure I can make them do the job but need assistance on how to actuate them. They work on 12V momentary pulse to actuate in one direction and then momentary reverse polarity to actuate in the other direction. I have 12V supply but am unsure how to get the reverse polarity to actuate in the opposite direction? Do I just need 2 x 12V supplies to a relay with one supply reversed (to suit how I will switch it)?

Bit hard to explain, havent done much with this for a couple of months as my brain overloaded last time!
 
One solution would be a (very) large capacitor in series with the actuator and a change over switch. Current will flow until the capacitor is charged. Unfortunately, the capacitor required might be huge depending on the current and time required to switch the solenoid.

Mike.
 


You need an "H-Bridge" to reverse the circuit as below. You may be able to buy a fully assembled H-bridge to drive this on eBay.

 
Add 10K pull down resistors from each of the switch throws to GND to guarantee that all four FETs are off in the wait state. The base resistors sorta kinda do this through the BJT base-emittter junctions, but not well.

ak
 
gophert said:
You need an "H-Bridge" to reverse the circuit as below. You may be able to buy a fully assembled H-bridge to drive this on eBay.

View attachment 114907
Click to expand...

Ooh, H-Bridges look technical! And the ones I am looking at look like they are for Arduino boards?

As I have 2 actuators that need to be controlled individually I guess that means 2 H-Bridges?

A thought I had was to use automotive door control relays? Pretty sure I would need 2 for each actuator

I found this diagram HERE and wondered whether it would work? Any thoughts on that would be appreciated thankyou!

Am trying to keep the control of it pretty simple if I can cheers
 
yes, yes, we can do relays too but my little computer with the easy schematic drawing app is being used by a guest. maybe someone else can help but you can look at the H-bridge and maybe figure out the DPDT relay. Or to recycle someone else's explanation...

 
Thanks, yes I saw that vid they other day and wondered whether it would do the trick!
 
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