Modeling Simulation and Validation of a Tractor Wet Clutch Controlled by Proportional Valve

Abstract

Wet clutch is a widely used machine element in the agricultural machines be-cause it allows the transmission of high torque with a more user-friendly turn on/off. In this article, the control of a wet clutch pack using a proportional valve in the power take-off unit is investigated. A wet clutch package is implemented on the transmission direct PTO shaft and actuate the power take-off unit of an ag-ricultural tractor. A one-dimensional mathematical model of the wet clutch and the electro-hydraulic control system was developed. Several actuation cases were simulated, and responses of all circuit elements were evaluated. Based on these predictions, test procedures with out-put torque values 300 and 600 N-m were set at 1.900 rpm unloaded engine speed. Variables, including speed, pres-sure, and temperature, were recorded in the experiments. The test and simulation results were compared. The clutch pressure increase was 10% under-predicted while the mainline pressure drop was 1% over-predicted. The proposed 1-D model can be further improved indeed. Yet, the acceptable agreement between the model and tests, offer less costly trial-and-error in the design and tune-up of future systems.

Keywords

• power transmission
• wet clutch
• hydraulics modeling
• PWM based control

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