Governor-like control system?

[fitterski]

I'm planning a snow-blower (posted elsewhere) possibly using an engine driven pump and one fan motor. I would like to devise control system that comprises 2 levers, one to set not-to-exceed engine rpm such as 2400, and another to set desired fan rpm such as 800. When the demand is low because I'm flying at 15 km/h in 2-3 inches of snow then I would want to engine to be commanded to supply just enough rpm to satisfy the load and keep fan rpm at the set value ...thence automatically modulating engine rpm as that load may vary from the cited one to crawling in 2 feet of the stuff.

Where on earth would I begin such a control design?

TIA

 

[aczlan]

I would use an add-on cruise control, JC Whitney used to sell them.

Aaron Z

 

[bigdeano]

If you get a Cummins truck engine I think they could be had with a governor for equipment use where constant speed is needed. The pump could probably be converted by an injector pump shop.

 

[fitterski]

If you get a Cummins truck engine I think they could be had with a governor for equipment use where constant speed is needed. The pump could probably be converted by an injector pump shop.

I fear what I have in mind is more complex, might require a variable volume pump, a centrifugal governor on the fan, and I don't know what else to divvy things up between the pump and the engine to serve up exactly the correct response.

 

[MossRoad]

I'm planning a snow-blower (posted elsewhere) possibly using an engine driven pump and one fan motor. I would like to devise control system that comprises 2 levers, one to set not-to-exceed engine rpm such as 2400, and another to set desired fan rpm such as 800. When the demand is low because I'm flying at 15 km/h in 2-3 inches of snow then I would want to engine to be commanded to supply just enough rpm to satisfy the load and keep fan rpm at the set value ...thence automatically modulating engine rpm as that load may vary from the cited one to crawling in 2 feet of the stuff.

Where on earth would I begin such a control design?

TIA

A long time ago there was a member here named Mark Chalkley. He bought a machine called an Earth Force. As I recall, he fitted it with a device from (I think, so don't quote me) Rexroth that would adjust the speed of the engine to meet the load required by the HST transmission. I think this is what you are talking about. Anyhow, this is one of the threads that got me looking at Power Trac machines instead of traditional conventional tractors. Its a good read. As I recall, this was a quite sophisticated machine and device, so guard your wallet.

Perhaps you can rig something a bit less expensive.

http://www.tractorbynet.com/forums/all-other-brands/7043-goodbye-kubota-hello-earthforce.html

As to your snowblower plans...

If you have an engine turning at X RPMS, and it spins a pump of fixed displacement of X cubic inches, it will put out X gallons per minute of fluid that will turn a motor at X PRMs. If you want your blower to turn at 800 RPM all the time, you need to keep that same amount of fluid going to the blower motor at all times. If you vary the engine RPMS, thats going to vary the pump speed and that's going to vary the blower motor speed. I don't think there's a way around that. You want the governor to add more fuel to keep the engine at the same RPMS and never let it variate from that RPM to maintain 800 RPM at the blower, yes?

 

[muddstopper]

Since this is the hydraulic forum, I will assume you are going to use a hyd motor to run your blower fan. If this is so, you can use a variable flow control to control fan speed. Set your engine rpms with a throttle stop. You can also get a throttle cable with a knob you just twist to adjust engine speed. It will push in for shut down and pull out for WOT and just twist the knob to adjust anywhere inbetween.

 

[fitterski]

A long time ago there was a member here named Mark Chalkley.....
http://www.tractorbynet.com/forums/all-other-brands/7043-goodbye-kubota-hello-earthforce.html

If you have an engine turning at X RPMS, and it spins a pump of fixed displacement of X cubic inches, it will put out X gallons per minute of fluid that will turn a motor at X PRMs. If you want your blower to turn at 800 RPM all the time, you need to keep that same amount of fluid going to the blower motor at all times. If you vary the engine RPMS, thats going to vary the pump speed and that's going to vary the blower motor speed. I don't think there's a way around that. You want the governor to add more fuel to keep the engine at the same RPMS and never let it variate from that RPM to maintain 800 RPM at the blower, yes?

Thanks for that link, it's a read-and-a-half but I bookmarked it and will eventually go through it all. Too bad all the old pictures and stuff are dead.

This control system is at this point way over my head, never worked with hydraulics in my life! With a mechanical setup it would be something I understand better: a certain gear & engine rpm for the fan speed and a fan-sensing governor on the engine, makes me thing of a torque converter, so that whatever fan speed I have selected would tend to maintain. Of course with most new engines being already digital there's another can of worms in there.

 

[MossRoad]

Thanks for that link, it's a read-and-a-half but I bookmarked it and will eventually go through it all. Too bad all the old pictures and stuff are dead.

This control system is at this point way over my head, never worked with hydraulics in my life! With a mechanical setup it would be something I understand better: a certain gear & engine rpm for the fan speed and a fan-sensing governor on the engine, makes me thing of a torque converter, so that whatever fan speed I have selected would tend to maintain. Of course with most new engines being already digital there's another can of worms in there.

See mudstopper's post above. Some good info there.

 

[oldnslo]

Rexroth does offer a control for their closed loop pumps that offers automatic transmission type drive where the pump will never stall the engine. It adjusts the pumps displacement based on engine RPM. I don't know if any other companies offer this type of mechanical control.

The more complicated you make this system the more stuff to go wrong.

 

[MossRoad]

I guess I don't understand why you want to re-engineer something that already exists??? A snowblower mounted on a truck or tractor, powered by either the vehicle's engine or a separate dedicated engine for the blower already exists.

Is this just a fun thing to do? If so, I'm with ya! :thumbsup:

If not, I can't sit around and watch someone poke themselves in the eye with a sharp stick.