CylinderSingleSpringReturn

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CylinderSingleSpringReturn

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Library

Iconic Diagrams\Hydraulics\Cylinders

Use

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

Description

CylinderSpringReturn1

This is the extended model of a single acting cylinder with mass, friction, end stops and a return spring to drive the cylinder back when there is no pressure in the chamber.

CylinderSingle-SpringReturn1

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

PistonDiameter

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

 

The travel of the piston is restricted. At the cylinder heads two collision models prevent the piston from traveling any further. The friction between the piston and the cylinder walls is modeled by static and viscous friction.

Interface

Ports

Description

pa

p_barrel, p_rod

hydraulic port

translation ports

Causality

 

preferred pressure out pa

preferred force out pm

 

Parameters

 

Vdead

B

stroke

x_initial

dp

m_barrel

m_rod

kc

dc

Fc

dv

slope

rest volume of oil in cylinder chamber when closed [m3]

effective bulk modulus [Pa]

stroke length [m]

starting position of piston [m]

piston diameter [m]

barrel mass [kg]

rod and piston mass [kg]

stiffness during collision with cylinder heads [N/m]

damping during collision with cylinder heads [N.s/m]

static friction [N]

viscous friction coefficient [N.s/m]

steepness of the static friction curve []

Note

When a the cylinder piston collides with the cylinder heads, simulation may get very slow or even become unstable. In these cases you are advised to use the BDF-method with default settings. Try to change the absolute integration error until a stable simulation is obtained!