Swash Plate
Inclined disc axial piston pump in an isothermal liquid network.
Description
The Swash Plate unit simulates a single piston driven inclined disc in an axial piston pump. It converts linear motion into rotary motion which, when connected to the Valve Plate Orifice (IL) unit, periodically connects the piston to the pump suction and discharge connections. Several Swash Plate units can be connected to several pistons.
*Swash Plate diagram in an axial piston pump.
Balance of forces
A disc is in dynamic equilibrium if the useful work of the piston, actuator and disc is zero:
where
-
- is the work done by displacement of the piston;
-
- work done by the displacement of the actuator;
-
- work done due to the useful torque of the disc tangential to its motion.
The torque of the disc is:
where
-
- is the value of the Cylinder block pitch radius parameters;
-
- is the value of the Swash plate actuator arm parameters;
-
- actuator displacement;
-
- piston force;
-
- angular movement of the plate.
The torque of the viscous friction forces, or resistance to movement due to disc contact with the piston, is:
where
-
- is the value of parameters Viscous friction coefficient;
-
- angular velocity of the rotor.
Piston dynamics
The movement of the piston is proportional to the movement of the actuator:
where is the value of the parameter Piston offset from the plate. The displacement will be positive if the piston is moving towards the cylinder block.
The piston speed is:
where is the speed of the actuator.
Ports
Conserving
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A
—
mechanical port associated with the actuator
translational mechanics
Details
Velocity and drive force of an inclined disc.
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P
—
mechanical port associated with the piston
translational mechanics
Details
Velocity and force of the piston.
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S
—
mechanical port connected to the shaft
`rotational mechanics
Details
The angular velocity and torque of a drive shaft. Rotation is performed relative to the environment.
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Parameters
Parameters
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Swash plate actuator arm —
actuator arm length
m | cm | ft | in | km | mi | mm | um | yd
Details
Length of the fully extended actuator lever.
| Units |
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| Default value |
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| Evaluatable |
Yes |
#
Cylinder block pitch radius —
radius of the initial surface of the cylinder
m | cm | ft | in | km | mi | mm | um | yd
Details
The radius of the initial surface of a rotating cylinder.
| Units |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
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Piston offset from the plate —
piston displacement in neutral position
m | cm | ft | in | km | mi | mm | um | yd
Details
Piston displacement when the actuator is in the neutral position. A positive non-zero value indicates a partially retracted piston. A negative non-zero value indicates a retracted piston that remains in the cylinder block during the initial displacement of the actuator from the cylinder.
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| Default value |
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| Evaluatable |
Yes |
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Viscous friction coefficient —
viscous friction moment coefficient
kg/s | N*s/m | N/(m/s) | lbf/(ft/s) | lbf/(in/s)
Details
A coefficient used in the equation for torque due to viscous friction.
| Units |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |