Abstract
The chapter deals with a numerical simulation of a machine-tractor unit with an elastic-damping mechanism installed between an engine and a tractor transmission while fulfilling an agricultural performance (sowing). The mechanism is a complex system. The description of an elastic-damping mechanism shows all its advantages. There has been given a theoretical substantiation of a transparency level effect on a machine-tractor unit performance while sowing. The purpose of the work is to conduct theoretical study to identify the effect of an elastic-damping mechanism in a tractor transmission on working characteristics of a sowing machine. There has been obtained a regression equation and identified optimum parameters of an elastic-damping mechanism installed in a tractor transmission. There has been also given a substantiation of an expediency to install an elastic-damping mechanism in a tractor transmission for sowing grain crops.
TopIntroduction
For promising and modernized tractors there are being developed various transmissions. The results of experimental studies of the existing types indicate a high dynamic load during such processes as starting from a standstill, shifting gears, as well as during steady modes of tractor motion. Taking into account a high cost of modern transmissions and additional costs of fixing them, the problem to reduce dynamic load in tractor transmissions is of great relevance.
It is believed that the introduction of additional elastic damping mechanisms (EDM) as active vibration filters at the entrance and exit of a transmission can provide a required level of protection of an engine and transmission elements from fluctuations of an external traction load. This makes a thorough study aimed at reducing dynamic loading especially important.
It is time consuming to carry out experiments with real objects or with physical models, so it’s reasonable to develop numerical simulations (mathematical models) using the results of simpler experiments. To simulate all the processes occurring in the transmission when the tractor is working is a relevant problem.
The known numerical simulations do not allow sufficiently taking into account the real design features, conditions and modes of a controlled tractor motion, their interaction with an environment, with an intensity of changes and their features.
We have proposed a tractor model with an elastic-damping mechanism (EDM) installed in a tractor transmission. An EDM is needed to reduce vibrations in the engine-transmission system. It is closely installed to the engine and well protects the engine and transmission from fluctuations of external loads. An EDM installation reduces a number of external effects, thereby protects an engine and transmission from high dynamic loads, and allows decreasing a possible drive wheel travel reduction (slip).
The proposed simulation (model) allows to study the effect of external traction load oscillations on the working characteristics of an engine, transmission, a whole unit. This model has made it possible to conduct a multi-factor experiment to find optimum parameters of the elastic-damping mechanism. The conducted study has proved the effectiveness of an EDM to reduce dynamic load of transmission units.
Key Terms in this Chapter
Planetary Reduction Gear: Is a mechanism comprising several planetary gears, rotating around a central (solar) gear. Planetary gears (satellites) are fixed by a carrier. A planetary gear includes another outside hollow gear geared inside with satellites (planetary gears).
Machine-Tractor Unit (MTU): Is a tractor connected to a working machine or machines. A tractor in the unit is a source of mechanical energy which helps the machine to move around the field, for example when a tractor pulls a cultivator.
Multi-Factor Experiment: Is an experiment that involves varying several factors, possibly affecting on the studied phenomenon.
Regression Analysis: Is a statistical study of the effect of one or several independent variables on a dependent variable.
Degree of Transmission Transparency: Is a filtration degree of oscillations from an external load to a power unit (engine). A very rigid transmission is called transparent, i.e. one that passes a reactive external load through itself without any changes.
Gear Change Box (GB): Is used to change a torque and to transfer it from engine to wheels.
Elastic-Damping Mechanism (EDM): Is a mechanism that dampens vibrations and dissipates energy inside the system under the effect of cyclic loads. In this case, the mechanical energy of the oscillations is converted into the thermal energy.