Interface between hydraulic and mechanical translational domains
The Translational Hydro-Mechanical Converter block models an ideal transducer that converts hydraulic energy into mechanical energy, in the form of translational motion of the converter output member, and vice versa. The compressibility option makes the converter account for dynamic variations of the fluid density.
Using this block as a basic element, you can build a large variety of hydraulic cylinder models by adding application-specific effects, such as leakage, friction, hard stops, and so on.
The converter is simulated according to the following equations:
|q||Flow rate to the converter chamber|
|A||Effective piston area|
|vR||Converter rod velocity|
|vC||Converter case velocity|
|F||Force developed by the converter|
|p||Gauge pressure of fluid in the converter chamber|
|α||Relative amount of trapped air|
|ρl0||Fluid density at atmospheric conditions|
|ρg0||Gas density at atmospheric conditions|
|γ||Specific heat ratio|
|βl||Bulk modulus at atmospheric conditions and no gas|
|ε||Converter orientation with respect to the globally assigned positive direction. If pressure applied at port A exerts force in positive direction, ε equals 1. If pressure applied at port A exerts force in negative direction, ε equals –1.|
The piston volume is computed according to
|Vdead||Chamber dead volume|
|x0||Piston initial position|
|x||Piston displacement from initial position|
Port A is a hydraulic conserving port associated with the converter inlet. Ports R and C are translational mechanical conserving ports associated with the rod and the case of the converter, respectively.
The block dialog box does not have a Source code link. To view the underlying component source, open the following files in the MATLAB® editor:
For incompressible converter implementation —
For compressible converter implementation —
matlabroot is your root folder.
The block simulates an ideal converter, with an option to account for fluid compressibility. Other effects, such as hard stops, inertia, or leakage, are modeled outside of the converter.
Effective piston area. The default value is
Specifies converter orientation with respect to the globally
assigned positive direction. The converter can be installed in two
different ways, depending upon whether it exerts force in the positive
or in the negative direction when pressure is applied at its inlet.
If pressure applied at port A exerts force in negative direction,
set the parameter to
Acts in negative direction.
The default value is
Acts in positive direction.
Specifies whether fluid density is taken as constant or varying
with pressure. The default value is
Off, in which
case the block models an ideal transducer. If you select
the block dialog box displays additional parameters that let you model
dynamic variations of the fluid density without adding any extra blocks.
Initial offset of the piston from the cylinder cap. The default
Volume of fluid in the chamber at zero piston position. The
default value is
Gas-specific heat ratio. The default value is
Initial pressure in the chamber. This parameter specifies the
initial condition for use in computing the block's initial state at
the beginning of a simulation run. The default value is
The block has the following ports:
Hydraulic conserving port associated with the converter inlet.
Mechanical translational conserving port associated with the rod of the converter.
Mechanical translational conserving port associated with the case of the converter.