Translational Hydro-Mechanical Converter
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||Mechanical orientation of the converter (|
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:
Basic Assumptions and Limitations
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.
- Piston area
Effective piston area. The default value is
- Converter orientation
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:
Pressure at A causes positive displacement of R relative to C— Increase in the fluid pressure results in a positive displacement of port R relative to port C. This is the default.
Pressure at A causes negative displacement of R relative to C— Increase in the fluid pressure results in a negative displacement of port R relative to port C.
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
On, the block dialog box displays additional parameters that let you model dynamic variations of the fluid density without adding any extra blocks.
- Piston displacement
Select method to determine displacement of port R relative to port C:
Calculate from velocity of port R relative to port C— Calculate displacement from relative port velocities, based on the block equations. This is the default method.
Provide input signal from Multibody joint— Enable the input physical signal port p to pass the displacement information from a Multibody joint. Use this method only when you connect the converter to a Multibody joint by using a Translational Multibody Interface block. For more information, see How to Pass Position Information.
This parameter is enabled when Compressibility is
- Initial piston position
Initial offset of the piston from the cylinder cap. This parameter is enabled when Compressibility is
Onand Piston displacement is
Calculate from velocity of port R relative to port C. The default value is
- Dead volume
Volume of fluid in the chamber at zero piston position. This parameter is enabled when Compressibility is
On. The default value is
- Specific heat ratio
Gas-specific heat ratio. This parameter is enabled when Compressibility is
On. The default value is
- Initial pressure
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. It is enabled when Compressibility is
On. 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.
Physical signal input port that passes the position information from a Simscape™ Multibody™ joint. Connect this port to the position sensing port p of the joint. For more information, see Connecting Simscape Networks to Simscape Multibody Joints. To enable this port, set the Interface displacement parameter to
Provide input signal from Multibody joint.
 Manring, N.D., Hydraulic Control Systems, John Wiley & Sons, New York, 2005
 Meritt, H.E., Hydraulic Control Systems, John Wiley & Sons, New York, 1967