| The homemade ZL15 small loader has been set for over 40 years,and the structure of its BYD2205 gearbox has not been greatly improved.The original gearbox has the advantages of simple structure,high reliability and low price,which has been adapted to the market form of decades before reform and opening up.With the development of the country,the equipment manufacturing industry has begun to upgrade,and the new environmental protection policy also put forward higher requirements for the environmental impact factors of construction machinery.Especially in terms of noise,the state has issued more stringent control standards.With the application of other zero part noise reduction measures,gearbox has become the second major noise source of ZL15 loaders.Therefore,it is imperative to de noise the existing BYD2205 transmission.This paper introduces the noise test,analysis,noise reduction design of BYD2205 gearbox and the verification process of noise reduction measures.First,the noise of BYD2205 gearbox is tested.A special test bed is designed to simulate the actual working state of the three aspects of the oil temperature,speed and load of the gearbox,and the noise of the BYD2205 gearbox on the loader can be obtained.The noise data of the gearbox on the test platform is collected by using the noise testing system of LMS.Frequency analysis of the data obtained from the test:first,the frequency of the maximum contribution of the gearbox noise is obtained,and then it is compared with the meshing frequency of each gear in the gearbox.In this way,a pair of gears with poor performance on noise can be obtained,providing data support for subsequent noise reduction design.By referring to the noise reduction method of gear transmission both at home and abroad,combined with the actual situation of the gearbox,we have determined the structural optimization plan.In this scheme,the involute helical gear is changed to an involute helical gear with a spiral angle of 15 degrees without changing the gear box(the center distance of the gear pair is constant)and without changing the gear transmission ratio(less than 3%).The scheme greatly improves the coincidence degree of gearbox gear pair,and theoretically can effectively improve the vibration and noise of gearbox.In addition,a pair of gears with high contribution to noise is achieved through technological improvement.Besides,the optimization design of gear modification and lubrication is carried out.On the other hand,because the engine of the loader has been upgraded,the torque of the engine's final input gearbox has increased by more than 11%.It is necessary to check the strength of the pafrts of the gearbox,so as to ensure its reliability.After checking the reliability of the original transmission with the new input parameters,it is found that the reserve coefficient of the original clutch is as low as 0.99,which can not meet the requirements of the use.In the limited change space,this paper improves the reliability of the clutch by means of increasing the number of clutch friction pairs,and meets the requirements of the new engine.Finally,a comparative test between the old and new gearboxes is carried out,and the design effect is verified through loading tests.The test results show that the design scheme achieves the expected design effect,and can reduce noise by more than 2 dB.Through the work of this paper,the gear is changed from the involute straight tooth to the involute helical tooth,and the gear grinding process is improved.These measures obviously reduce the noise.The influence of the new power system on the gearbox is confirmed.By adding 2 pairs of friction pairs,the reserve coefficient of the shifting clutch is increased by 50%.The test shows that the new design greatly improves the reliability and comfort of the original gearbox.It is an important improvement design for existing products,which can meet the needs of high-end market at home and abroad for a period of time,and is in the leading position in China. |
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