Tractor Transmission Energy Flow Chart

This example shows how to 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.

Model

The figure shows the hydrostatic CVT tractor model.

Hydrostatic CVT Subsystem

This subsystem demonstrates how to model the hydrostatic transmission. Here, connection Engine is a physical signal port associated with the speed source representing the engine. Connection Shaft is a physical signal port associated with the transmission shaft connecting with the final drive of the Tractor. Connection SAE 5W-30 is a physical signal port associated with the fluid properties of the Isothermal Liquid network that represents the transmission hydraulics. Connection Displacement is a physical signal port associated with the axial piston pump displacement command. The driver provides the swash displacement command in a tractor. The charge pump maintains the minimum pressure in the low pressure line of the circuit. The relief valves limit the maximum pressure in the circuit's high pressure line.

Energy Chart Computations: This subsystem shows the energy chart of the tractor transmission system. The green dashed line shows the fluid flow path while in reverse, and the orange line shows the fluid flowpath while in forward gears. The pump displacement is positive for the forward gear and negative for the reverse gear tractor operation. You can compute the available, useful, recirculated, wasted energies as well as the efficiency of the components from the energy flow chart.

Energy Calculations: This subsystem Relief Valve A Energy Computation shows how to perform energy calculations for a relief valve.

Simulation Results from Simscape™ Logging

This model generates a plot of the tractor velocity, engine speed, and transmission speed.

This model also generates a plot of the input and output energies of the pump and motor.