Its a pretty interesting technology. It is basically a big slug with a metting pin to control the Delta P on both sides. Pretty durable as long as you keep big pieces of metal out of the system - the slug can close so hard that it peens the seat if metal is in the way!

Like anything else it has ups and downs. The cost was the same as a comparable electro-hydraulic pilot solenoid controlling a spool. One positive is that it doesn't need pilot pressure, which can give you lowering with engine off capability. It can also be replaced as a cartridge. On the control side there is some hysteresis and non-linearity which may or may not be a problem depending on your needs.

As far as regeneration I don't see why not. I found an article in the 5/5/2005 edition of MachineDesign.com which talks about the Incova being used on JD backhoes with regeneration. They also used 4 valves per cylinder to perform some whiz-bang functionality. We only used 2.

As far as implementation - our software was the biggest growing pain. We also had to learn what kind of beast we were dealing with :) Just like anything new and different.

After 3 yrs of development I am pretty pleased. Unfortunately, due to some early problems and misunderstandings, my former company has desided to strike out on a different path on future projects. Its a shame as all the issues are worked out now.

Cheers

I had read about the JD backhoe, but was not sure how the regeneration was done. What type of product is this used on?
Did the hystresis or non-linearity cause any control delays? Or is it just a matter of getting use to the controls?
We are considering using the Incova system with joystick controls, so your experience is greatly appreciated.

I know that we were more demanding than the JD application. :) The operators are very picky - they want high flow to reduce cycle times and very fine controlable flow on demand.

In our application the hysteresis wasn't a big deal, I just used the conservative curve in my software, which in this case was the lower flow for a given mA.

The non-linearilty is constant from valve to valve if you have pressure compensation, which we had on one of the valves, so we were able to eliminate that with a software curve. The other valve used gravity only, so it didn't have pressure compensation, and had different linearity curves depending on the load on the cylinders. This was a pain and took me about two solid months of fooling around with the software curves to get a good compromise. It was worth it in the end though, as the final software and produced controllability better than anything else on the market.

There were no delays due to the hardware - just the CAN bus running at 100hz and the computer processing time. In actuality it was almost too quick. Any flinch in the controls was immediately transmitted to the valve. We got into a human/machine resonance problem and had to dampen the controls a little.

The other issue to be aware of is the variance in cracking current between valves. This can be dealt with in several ways.
1. Perform a manual on vehicle calibration for each function through a software routine. cheap, but relies on humans to get it right. And if it is wrong the software curve doesn't match the actual valve performance.

2. Perform an automatic on vehicle calibration for each function through a software routine and some type of position or pressure sensor. Ideal, but requires sensors. I believe this is what JD does.

3. Initiate the current below the level of the production tolerance. Very cheap, but you sacrafice some of the control range. Instead of using 90+% of the joystick range you would have to live with only ~75% being usefull. This may or may not be important in your application, and will depend on what size of controls you have. Ours was only 2", so we needed all the range we could get.

If you go with these valves let me know. I have a lot more detailed info I could share.

You might want to check out this Forum about the same type of valves.

http://www.ifps.org/phpBB2/viewforum.php?f=1&sid=c4837ca1d8e0261ee47c42bcb97edb3c

"DIN Cartridge Valves vs Subplate mounted"

Bud Trinkel CFPE
HYDRA-PNEU CONSULTING, INC.
http://www.fluidpower1.us