Engine Speed Control System for Improving the Fuel Efficiency of Agricultural Tractors for Plowing Operations

Abstract

This study was conducted to develop a load-sensitive engine speed control system to maximize the fuel efficiency of an agricultural tractor. The engine speed controller was developed through a model-based design approach using a tractor simulation model. The simulated engine speed and torque values were measured with an average error range of 1.4-4.9% compared to results obtained from field experiments. Using the tractor model, the gain parameters of the proportional-integral (PI) controller were optimized under the step, ramp, and actual load conditions. The simulation results using the actual load showed that the engine speed could be adjusted to within 2-3% of the desired value using the proposed engine speed controller. The throttle control system was constructed using four parts of a tractor engine, a microprocessor with an engine speed control algorithm, a throttle actuator, and a data acquisition system. Using the developed system, the operating engine speed values showed an average 1.17 % error compared to the desired engine speed. Three fuel efficiency parameters were used for evaluating the fuel-saving performance of the control system: specific volumetric fuel consumption (SVFC), fuel consumption per tilled area (FCA), and fuel consumption per work hour (FC). The values for SVFC, FCA, and FC obtained from the engine speed control system during plowing operations were 23.03-57.87%, 4.11-42.06%, and −7.24-38.48%, respectively, showing an improvement over the same operations without the control system.

Simulation of Fuel Consumption Based on Engine Load Level of a 95 kW Partial Power-Shift Transmission Tractor

“…The results indicated that the gear selection of 7.56 km/h (M2-High) was highly beneficial to conduct plow tillage operation using the 95 kW partial PST tractor considering high engine torque. To optimize the fuel consumption, the gear selection should be shifted to the M2-High instead of M3-Low because M3-Low generates low engine torque that might be suddenly turn-off the engine due to high soil strength [14].…”

“…In this study, the plow tillage load was also applied to generalize the verified simulation model. The representative plow tillage load data was calculated from literature [14]. To select the suitable gear stage at low fuel consumption, the representative load data was plotted in the engine performance curve that generalized the simulation model for agricultural operations.…”

“…Therefore, the engine speed should be adjusted within the ungoverned region where the working efficiency was comparatively higher but the fuel consumption was relatively lower. The plow operation loads, which were calculated comparing with the literature [14], were performed for two gear selections. M2-High and M3-Low were 7.56 km/h and 9.81 km/h, respectively, which were selected to perform plow tillage at the same agricultural field.…”

“…The fuel consumption of the tractor depends on workloads because the working loads are varied by operation conditions such as engine speed, soil properties of the field, operation types based on implements, and transmission gear stages. Among them, the engine speed and transmission gear stages mostly affect the fuel efficiency of the tractor [14]. The fuel efficiency of the tractor can be optimized by adjusting engine load conditions.…”

“…The performance was reported as better than the existing mechanical governor. Lee [14] developed a model-based controller for fuel consumption based on working loads during plow tillage operation. Therefore, the engine load level is an important factor to estimate the optimal fuel consumption of the agricultural tractors.…”