Quote:
Originally Posted by Ether
How is this possible? Can you explain what is happening?
(I assume by "energy" you are referring to the energy delivered into the load)
~
|
I'll give it a try.
I define Energy as the integral of net force on load*piston speed.
If the valve is able to keep the pressure high then it pays to have a longer stroke since the force is higher. The gain in energy due to longer stroke outweighs the gain from precharging with a reduced stroke.
Precharging makes use of potential energy which is limited by the %initial_stroke*area of piston. The input energy is negligible relative to the large area pistons. When the pistons get small enough, the input energy becomes significant and is like a power supply so you don't have to rely on potential energy to deliver the goods.
In the limiting case.... if you had a huge valve or infinite flow to the cylinder, then the pressure drop would be negligible and the work done would be Psupply*Area*stroke which is the best the piston can deliver.