Development of a Simulation Model for HMT of a 50 kW Class Agricultural Tractor

Wan-Soo Kim,Seung-Yun Baek,Yong-Joo Kim,Seung-Min Baek,Yeon-Soo Kim

doi:10.3390/app10124064

Abstract

This study was conducted to develop a simulation model of a 50 kW class hydro mechanical transmission (HMT) tractor and to verify the model by comparing the measured and simulated data, including the axle torque, rotational speed, and power transmission efficiency. The platform of the HMT was composed of the engine, hydrostatic unit (HSU), compound planetary gear, range shift, spiral bevel gear, and final reduction gear. The HMT had three gear stages and a maximum forward speed of 40 km/h. To evaluate the performance of the HTM, a test bench was installed based on the engine of the HMT platform, and a simulation model was developed using 3D simulation software. To compare the results of the simulation, a bench test using the platform was performed according to the gear stages. The similarities between the measured and simulated data were analyzed using the t-test. As a result, there were no significant differences for the axle torque, rotational speed, and power transmission efficiency. Finally, the power transmission efficiency between the measured and simulated results was compared and analyzed using linear regression analysis to validate the accuracy of the simulation model. The trend of the power transmission efficiency between the measured and simulated results appeared to be similar in all sections, and we obtained a simulation model with the accuracy of an R-squared value of more than 0.97. In conclusion, the measured and simulated results were similar to each other. Considering the results of this study, it will be useful to develop the HMT tractor and to improve the power transmission efficiency for the optimal design.

Highlights

The growing role of agricultural mechanization and the need to save fossil energy are important factors in the fuel consumption and emissions of agricultural machinery, such as tractors [1,2,3]
The results showed that the hydro mechanical transmissions (HMT) continuously shifted the hydrostatic unit (HSU) stroke to perform gear selection and increased the driving speed of the tractor, and the power transmission efficiency of the HMT increased as the driving speed increased for each gear stage, and decreased again after reaching the maximum point
The objectives of this paper were (1) to develop a prototype of an HMT tractor; (2) to develop a simulation model that reflected the specifications of the parts used in the prototype of the HMT platform; (3) to collect load data through the bench test for the axle torque, rotational speed, and power transmission efficiency; (4) to verify the simulation model through a comparison of the measured and simulation results according to gear stages

Summary

Introduction

The growing role of agricultural mechanization and the need to save fossil energy are important factors in the fuel consumption and emissions of agricultural machinery, such as tractors [1,2,3]. Power transmission is a critical component of a tractor and has evolved from traditional manual transmission (MT) into newer continuously variable transmission (CVT), and dual clutch transmission (DCT). CVT is a variable solution to retain the characteristics of stepless speed regulation and maintain a high efficiency and to improve fuel efficiency by adjusting the engine operating conditions [7,8,9]. CVTs can be classified into V belt types, hydrostatic transmissions (HST), and hydro mechanical transmissions (HMT) [10]. The power level is too low to meet the requirements of agricultural machinery, such as tractors [11,12]

Objectives

Methods

Results

Discussion

Conclusion