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# CylinderSpringReturn

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# CylinderSpringReturn

## Library

Iconic Diagrams\Hydraulics\Cylinders\Basic Cylinders

## Use

Domains: Continuous. Size: 1-D. Kind: Iconic Diagrams (Hydraulics/Translational).

## Description

This is an ideal model of a single acting cylinder with no mass and no friction and a return spring to drive the cylinder back when there is no pressure in the chamber. The volume of the chamber is given by:

V = Vdead + Aa*(x + x_initial)

with Aa the piston area, x the piston position and Vdead the initial volume when piston position is zero. The piston area Aa is related to the piston diameter dp by:

Aa = pi * dp^2 / 4

The driving force of the return spring is determined by two parameters: the force for piston position zero (Fspr_min) and the force when the piston is at the other side (Fspr_max). The spring constant (kspr) and initial spring position (x0) are calculated out of these parameters by:

kspr = (Fspr_max - Fspr_min)/stroke

x0 = -Fspr_min/kspr

There is no restriction on the travel of the piston. Only a warning is given when the maximum stroke is exceeded or the piston position gets negative.

## Interface

 Ports Description pa pm hydraulic port translation port Causality preferred pressure out pa preferred force out pm Parameters Vdead stroke x_initial dp Fspr_min Fspr_max rest volume of oil in cylinder chamber when closed [N.s/m] stroke length [m] starting position of piston [m] piston diameter [m] minimum return spring force (at x = 0) [N] maximum return spring force (at x = stroke) [N]