Other reasons include:
- Valve located far from the cylinder.
- Hose from valve to cylinder instead of hard tubing.
- Poor resolution feedback
- Noisy feedback
- Inconsistent system pressure
- Poor quality valve
about “- Valve located far from the cylinder.
- Hose from valve to cylinder instead of hard tubing.”
how to Calculate the Influence。
Can i get a example.Many projects have this problem in our company。
i want to Calculate them。
Many valves are currently focused on a valve block, in order tofacilitate the arrangement of piping。
is This means not incorrect?
in the “DOs and DON’Ts of Hydraulic Position Control System Design” refers that
“Place Valves on Cylinders Mount valves on the end and on top of the cylinders. Keep the trapped volume of oil between the valve and the piston as small as possible”
In the hydraulic control system，is This the key of Good hydraulic system ？
Keeping the trapped volume of oil between the valve and the piston as small as possible is one of the keys, and it is a very important key. this is the same as pushing a mass with a spring. To achieve good control, it is important to keep the spring as stiff as possible. The trapped oil is a spring, so it should be kept small.
However, for very large cylinders (such as 12" bore and long stroke), it can be acceptable to mount the valve a little ways (3 feet or so) from the cylinder since the trapped volume of oil is very small relative to the cylinder volume.
The importance of the trapped oil volume also depends on the required motion profile. If the cylinder does not need to accelerate quickly, then the distance between the valve and the cylinder is not so critical.
The importance of the trapped oil volume also depends on the cylinder construction and the load. If the cylinder or load has a high static friction compared to dynamic friction, then it is important to keep the trapped volume small, otherwise that volume acts like a large spring, which makes it very difficult to control the load. It is very easy to imagine trying to push a mass with a spring. If the mass has a large static friction, and the spring is very “springy”, the load will tend to “slip and stick”.
Calculating the influence is very difficult. Some simulation programs exist. Maybe Peter has some simulations.
thanks Jacob Paso . I understand Understand what you mean。you give me a lot of inspiration
I hope peter give me a more detailed explanation