Interface between hydraulic and mechanical rotational domains
The Rotational Hydro-Mechanical Converter block models an ideal transducer that converts hydraulic energy into mechanical energy, in the form of rotational motion of the converter shaft, and vice versa. Physically, the converter represents the main component of a single-acting rotary vane actuator. 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 rotary actuators 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|
|D||Converter displacement, or fluid volume needed to rotate the shaft per angle unit|
|ωS||Converter shaft angular velocity|
|ωC||Converter case angular velocity|
|T||Torque on the shaft|
|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 generates torque in positive direction, ε equals 1. If pressure applied at port A generates torque in negative direction, ε equals –1.|
The piston volume is computed according to
|Vdead||Chamber dead volume|
|θ0||Shaft initial angle|
|θ||Shaft rotation from initial position|
Port A is a hydraulic conserving port associated with the converter inlet. Ports S and C are mechanical rotational conserving ports associated with the shaft and the case of the converter, respectively. Pressure at port A generates torque in the direction specified by the Converter orientation parameter.
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 converter displacement. 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 generates torque in the
positive or in the negative direction when pressure is applied at
its inlet. If pressure applied at port A generates torque 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 rotational conserving port associated with the shaft of the converter.
Mechanical rotational conserving port associated with the case of the converter.