A METHODOLOGY FOR MEASURING THE EFFECTS OF TRANSIENT LOADS ON THE FUEL EFFICIENCY OF AGRICULTURAL TRACTORS

Fuel efficiency is an important characteristic of a vehicle’s engine. Improved fuel efficiency will result in both environmental and economic benefits. In spite of the fact that the content of transient load components is extensive in many normal driving operations, measurements of fuel efficiency for agricultural tractor engines are normally carried out in steady–state conditions, i.e. at constant engine speed and loading torque. This article presents a methodology for estimating the effects of transient load components on the fuel efficiency of agricultural tractor engines. One application of the method is quantifying the effects of transient loads, to evaluate the accuracy of fuel efficiency and engine emission tests based on steady–state conditions. Another area of use may be in work to improve the engine and drive train characteristics with the aim of minimizing the transient effects. Measurement equipment includes strain gauge transducers, fuel consumption and engine speed sensors. The equipment also measures the fuel consumption and the engine speed. The results of measurements performed to test the methodology show that the transient parts of the load at the engine have important effects on the fuel efficiency. The decrease in fuel efficiency relative to steady–state based calculations was approximately 13% for a normal front end loading operation and 7% when driving on the farm without any implement attached. The tractor tested was supplied with a turbocharged engine with special equipment to reduce the smoke produced at sudden load changes, and the effects on fuel efficiency would probably be even greater if engines without this device were tested.