The Noise Character Research Of Automobile Transmission

The NVH performance of the transmission directly affect the ride comfort and is also the key link of automobile sound quality. The main contents of the current research for transmission are reducing the energy consumption and vibration noise in the condition of the original or higher bearing capacity.Therefore low noise and lightweight is the focus of domestic transmission research. Currently the main noise problem of domestic transmission is gear whine, gear rattle and special fault noice .In this paper,firstly the mechanism of gear transmission system noise is analyzed and summarized The physical process of the noise is detailed analyzed, which include the formation, transmission, radiation of transmission noise. A dynamic analysis model of cylindrical gears is build and the effect of meshing stiffness and profile error is emphatically studied. Then,spur gear transmission system is made the basis research object.Firstly the three-dimensional entity model of the box is set up.Then the finite element analysis model is established and the accuracy of the finite element mesh was controled. The natural frequency and vibration mode was calculated. Through experimental modal, the accuracy of the finite element model is verified . Then the radiation noise is predicted by combining the test data with the finite element model. The combining of the finite element model and the experiment data can greatly improve the forecast precision and speed in the initial NVH design. Many research institutes currently are using this method.A domestic car make a big noise in the neutral condition.A series of experiments, including the interior noise test and engine vibration test.,are designed to find the possible noise source. Through spectrum analysis the input shaft bearings is identified to be the may transmission noise source. In consider of the low cost, low development cycle and the reliability, the input shaft bearings are replaced. By changing the number of roller bearings, bearing's inherent frequency is changed.Thus it avoid engine incentive frequency and interior noise levels were significantly improved.This research solve the quality problems of a new car,and consumer's acceptance has been achieved and good economic benefit has been obtained.A precursor of domestic transmission exists serious gear whine at 5rd gear.Firstly.The interior noise test and bench test are made. Based on the test data , the main reduction gear pair's second order and the first order of the fifth gears pair were equal ,which was found by the order analysis combined spectrum analysis. Secondly, by acoustic contribution amount analysis, the main possible noise source are found.It may be the fifth gears pair or the main reduction gears pair.Thirdly ,through comparing and analysising of the contact spot of the fifth gears pair and the main reduction gears pair, final noise source is found ,which is the main reduction gears pair . In the end , the main reduction gears pair's design parameters were changed , and gear whine is reduced.In this paper,the noise mechanism of the auto transmission was studied. Prediction of radiation noise is executed based on the noise mechanism .Author solved two typical noise problem of domestic transmission . Good economic benefit has been got.