Swash plate in a single-piston, isothermal axial piston pump
Simscape / Fluids / Isothermal Liquid / Pumps & Motors / Auxiliary Components
The Swash Plate block models a single, piston-actuated swash plate within an axial-piston pump. It translates linear actuation into rotational motion that, when connected to the Valve Plate Orifice (IL) block, periodically connects the piston with the pump intake and discharge. You can connect multiple swash plate blocks to multiple pistons.
Schematic of a Swash Plate Within an Axial-Piston Pump Unit
The plate is in dynamic equilibrium if the net work by the piston, actuator, and plate is zero:
FPδP is the work done due to piston displacement.
FAδA is the work done due to actuator displacement.
(τ-τres)δy is the work done due to the net plate torque tangent to plate motion.
The plate torque is:
rP is the Cylinder block pitch radius.
rA is the Swash plate actuator arm.
XA is the actuator displacement.
FP is the piston force.
γ is the plate angular displacement.
The viscous friction torque, or the resistance to motion due to plate-piston contact, is:
μviscous is the Viscous friction coefficient.
ω is the rotor angular velocity.
The piston displacement, x, is proportional to the actuator displacement:
where hoff is the Piston offset from the plate. Displacement is positive if it moves toward the cylinder block.
The piston velocity is:
where VA is the actuator velocity.
Assumptions and Limitations
This block accounts for the effect of viscous friction between the piston and plate, but neglects plate and fluid inertia.
This reference page is for the Isothermal Liquid library block. For the Hydraulics (Isothermal) Liquid library block, see Swash Plate.
A — Mechanical port associated with actuator
Swash plate actuator velocity and force.
P — Mechanical port associated with piston
Piston end velocity and force.
S — Mechanical port associated with shaft
Drive shaft angular velocity and torque. Rotation is relative to the environment.
Swash plate actuator arm — Length of actuator extension
0.065 m (default) | positive scalar
Length of fully extended actuator arm.
Cylinder block pitch radius — Cylinder pitch radius
0.05 m (default) | positive scalar
Pitch radius of the rotating cylinder.
Piston offset from the plate — Resting piston offset
0 m (default) | scalar
Piston offset when the actuator is in neutral position. A positive, nonzero value indicates a partially retracted piston. A negative, nonzero value indicates an extended piston that remains within the cylinder block during an initial actuator displacement away from the cylinder.
Viscous friction coefficient — Torque viscous friction coefficient
50 N/(m/s) (default) | positive scalar
Coefficient used in the equation for torque due to viscous friction.
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