Pumps and Motors

Fixed- and variable-displacement devices for mechanical-hydraulic energy conversion

Use these blocks to model pumping in the isothermal liquid domain.

Simscape Blocks

Fixed-Displacement Motor (IL)	Fixed-displacement motor in isothermal liquid system (Since R2020a)
Variable-Displacement Motor (IL)	Variable-displacement motor in an isothermal liquid system (Since R2020a)
Fixed-Displacement Pump (IL)	Fixed-displacement pump in isothermal liquid system (Since R2020a)
Variable-Displacement Pump (IL)	Variable-displacement pump in an isothermal liquid network (Since R2020a)
Pressure-Compensated Pump (IL)	Constant-pressure, variable-displacement pump in an isothermal liquid network (Since R2020a)
Centrifugal Pump (IL)	Centrifugal pump in isothermal liquid network (Since R2020a)
Jet Pump (IL)	Liquid-liquid jet pump in an isothermal liquid network (Since R2020a)
Swash Plate	Swash plate in a single-piston, isothermal axial piston pump (Since R2020a)
Valve Plate Orifice (IL)	Variable orifice in an isothermal axial-piston machine (Since R2020a)

Featured Examples

Hydraulic Axial-Piston Motor

An axial piston motor with a test harness. To increase the fidelity of the simulation, this model uses a detailed representation of the motor that accounts for the interaction between the pistons, swash plate, and valve plate.

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Hydraulic Axial-Piston Pump with Load-Sensing and Pressure-Limiting Control

A test rig designed to investigate the interaction between an axial-piston pump and a typical control unit simultaneously performing the load-sensing and pressure-limiting functions. To increase the fidelity of the simulation, this example uses a detailed model of the pump that accounts for the interaction between the pistons, swash plate, and valve plate.

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Lubrication System

A simplified version of a lubrication system fed with the centrifugal pump. The system consists of five major units: Pump Unit, Scavenge Unit, Heat Exchanger Manifold, Nozzle Manifold, and Control Unit. Both the pump and the scavenge unit are built around the centrifugal pump. The Scavenge Unit collects fluid discharged by nozzles and pumps it back into the reservoir of the Pump Unit. The Control Unit generates commands to bypass either the heat exchanger, represented as a local resistance, or the nozzles block. In a real system, these commands are generated by temperature sensors installed in lubrication cavities.

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Priority Valve Controlling Two Hydraulic Motors

A pressure-compensated 3-way flow control valve. This valve maintains constant flow rate through the main hydraulic motor, which is connected to the pressure-compensated outlet of the flow control valve. It acts as a priority valve, diverting the excess flow to the auxiliary hydraulic motor if the main hydraulic motor receives enough fluid to maintain a preset angular velocity. The auxiliary motor is shut off completely if there is insufficient flow to power the main hydraulic motor.

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Hydrostatic Transmission

A hydraulic transmission system built of a variable-displacement pump and a fixed-displacement motor. The pipes between the pump and the motor are connected by two replenishing valves (check valves) and a charge pump on the pump side and two pressure relief valves on the motor side. The motor drives a mechanical load consisting of an inertia, viscous friction, and time-varying torque. The system is tested with both positive and negative pump flow rate by varying the pump displacement.

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Power-Assisted Steering Mechanism

A simplified version of a power-assisted steering mechanism. The hydraulic actuation system includes a double-acting hydraulic cylinder, 4-way valve, fixed-displacement pump, and a pressure-relief valve. The steering rack acts against a load modeled by a spring and damper.

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Hydraulic Axial-Piston Pump with Load-Sensing and Pressure-Limiting Control

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Tractor Transmission Energy Flow Chart

Model, parameterize, and test a tractor with a hydrostatic continuously variable transmission (CVT). When you run one of the plot functions, you can view plots of the tractor velocity, engine speed, transmission speed, and pump and motor energy computations.

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Servo Valve with Custom Fidelity

Compares the mechanical performance of various spool actuation configurations and model fidelity levels for a hydraulic 4-way 3-position directional valve. The directional valve controls a simple double-acting cylinder in a closed-loop application. This example allows you to choose among four different spool actuation designs:

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