Abstract
Wheel-type tractors carry out a range of processing operations, with the exception of early spring work, when caterpillar tractors are used to reduce the compaction effect on the soil. Therefore, to plan the costs and reserves associated with fuel consumption, it is necessary to have an estimate of the fuel economy of the tractor in basic agricultural operations. An objective assessment of fuel consumption requires a mathematical model that describes the fuel characteristics of the engine, taking into account the speed and load torque in a wide range of variation. Verification of the model is possible only with experimental data. Since the efficiency and fuel economy of a tractor depends not only on engine performance, but also on the perfection of the transmission, the running system and the rational choice of speed, it is necessary to take into account the time-varying nature of the tractor’s traction load. The complex of agricultural operations can be divided into characteristic cycles of load change over time. This principle is the basis of PowerMix test cycles, which are conducted on a concrete track to ensure repeatability of the experiment. The use of the variable load on the tractor in the PowerMix tests is positive, but in actual field tests the results may differ due to the instability of the soil properties. On the other hand, PowerMix field cycles can be taken as standard test loads in the simulation of tractor traction tests on the ground
Highlights
To assess fuel economy and determine hourly fuel consumption in partial engine operation modes, a model [1,2,3] is used that takes into account the crankshaft rotational speed and engine load in terms of power relative to the rated power taken through the tractor power take-off shaft
An alternative may be the DLG test protocols according to the PowerMix procedure [7], which, in terms of engine testing, is carried out according to the OECD Code 2 protocol [9], which assumes measurements of fuel consumption in partial modes when loading at a speed εω and power εN according to the Table 1
The proposed method for approximating the specific fuel consumption of a diesel engine is based on experimental test data on a full-throttle characteristic and on partial engine operation modes
Summary
To assess fuel economy and determine hourly fuel consumption in partial engine operation modes, a model [1,2,3] is used that takes into account the crankshaft rotational speed and engine load in terms of power relative to the rated power taken through the tractor power take-off shaft. To achieve the intended aim, it is necessary to complete the following objectives: – to formulate a methodology for approximating the fuel characteristics of the engine using the experimental data of the external speed characteristics and partial engine operation modes; – to develop a mathematical model of the characteristics of a diesel engine to determine the traction dynamics of a wheel-type tractor and to test it in a simulation with PowerMix field cycles. Where εω – ratio of reduced- and full-throttle engine speeds at operating load (decimal); εNe – ratio of reduced- and full-throttle engine power at operating load (decimal):
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