Hopper level sensor/switch question for stokers

My expertise lies in industrial automation. Unfortunately, I'm a mechanical guy, but I do specifiy the sensors on the equipment that I design. I don't worry too much about what controls them though so I don't know what you'd have to rig up to turn the auger on and off. Maybe a simple relay and a timer or a high and low switch through some relays would do the trick.

I can tell you that if you're looking to add a sensor to your hopper, you should be looking for a capacitive type and I would use IFM Efector as my brand of choice, but that's because we get huge discounts for using them in volume. Capacitive switches look for a change in density so they'll work regardless of the material. The other thing that's neat about them is that they can get "taught" to see through things like the walls of the hopper so they can be mounted without drilling the hopper. The only industrial alternative to this would be sonar or optical. I don't know much about sonar, but I think it would be much more expensive and optical would pose issues because they would get dirty very quickly.

There are plenty of solutions out there I'm sure, but in injection molding machines, they convey plastic resin to hoppers on the molding machines (i.e. conveying coal to a hopper on your stove) and they all use capacitive sensors in the hoppers to signal a the feeder to run.

Attached an image of a hopper for a injection molding machine and to the side is an orange sensor which is an IFM Efector capacitive switch.

I have a set up where I auger feed my hopper and thought about having it auto fill.
but the fact that when the hopper needs filling the ash pan needs emptying.
So what I do is when I go down to empty the ash pan, I switch on the hopper feed auger and by the time I finish with the ashes,
the hopper is full and I turn off the auger feeding the hopper.

I figured as dirty and corrosive as coal is, any auto fill would eventually fail and I would have a mess.

I did make up a simple way to know when the hopper is empty and ash pan is full, it has been working well for 2 years.
I'll post it below ( I also believe in the KISS method )
build a hopper empty/ash pan full indicator ....cheap

I imagine that a similar snap switch and counter mechanism could count the rotations of the Pitman Arm on the ashing system of the AHS Coal Gun and thereby indirectly indicate the hopper fill level to some degree of accuracy.

here is my auger feed hopper I posted in 2008, it is still working fine.

homemade auger feed coal bin

syncmaster wrote:here is my auger feed hopper I posted in 2008, it is still working fine.

homemade auger feed coal bin

Very nice work!