Project title: Experiment and improvement on noise reduction and efficiency of gears in diesel engine Thesis:
In most machines, the major requirements for gear transmission are low sound excitation character, a high-level load carrying capability and generally high efficiency, which is more vital with increased environmental awareness. This paper discusses and analyzes two main elements gear system efficiency improvement and sound excitation. The main reason in noise reduction at gear system is given. Recommendations for reduction in sound excitation and looses in gear mesh have been given. Abstract
Noise from heavy machinery that depends on gears such as heavy tracks, heavy-duty generators, has become a significant environmental concern. The levels of noise from the gearbox can be very disturbing to the personnel operating the machine and the general population. Gear noise is becoming an important factor to put into consideration during the design of gears, especially due to the allowable noise levels that machines should emit for environmental safety (Society of Automotive Engineers 56). Various factors play an integral role towards the generation of noise by such machineries. Gear dynamics and noise are the most underdeveloped areas in the studies involving gear design; this has caught the attention of many current studies. The kinematic design and geometric design, the mathematical modeling of gearboxes, and vibration analysis of gears are the key principles in attempting to model a good gear system. It is becoming necessary to put into consideration the vibration characteristics of gear systems and the meshing transfer error fluctuation in order to help in the reduction of noise during gear transmission. So far, research studies reveal that vibration characteristics of gear systems include the effect that the gear train structures have in the levels of rigidity of the significant meshing points, rib arrangements (Society of Automotive Engineers 58). Limited research has been conducted regarding the vibration transfer in a gear system that has an output crankshaft and the gear casing. It is therefore imperative to have an understanding of the noise generating mechanism in gears in order to develop a gear system has low noise during transmission; in addition, it is important to have an understanding of how the casing affects gear noise during transmission. In this regard, study provides an overview of the noise generating mechanism in gear systems, and provides a guideline for the development of gear systems that have low-vibration structures in order to reduce noise in gears. This experiments attempts to investigate the gear noise and the transmission error in gear systems. Conventionally, the Transmission Error is viewed as one of the causation factors that are responsible for excitation of noise in gear systems (Society of Automotive Engineers 66). Transmission Error is defined as the difference that exists between the real location of the crankshaft gear and the location that the output gear should be if it was considered as an ideal gear. Variables such as Dynamic Error Transmission have to be measured in order to determine the susceptibility of a gearbox to noise generation and the effect on its overall efficiency. The experiment was performed on a simple gearbox powered by diesel. The relationship between the Dynamic Transfer Error and the levels of noise was determined. A transfer function can be used to evaluate the relationship between the gear noise levels and the Dynamic Transfer Error. It is evident that the structural orientations of the gear units determine the efficiency excitation of the gear system. For instance, teeth deflections affect the transmission error. However, it does not necessarily mean that a reduction of the Dynamic Transmission Error translates into noise reduction by gear systems (Society of Automotive Engineers 56). The principal aim of the...
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