| With the rapid development of industry,the application of construction machinery is increasing gradually.As the "king of construction machinery",excavators are widely used in various engineering fields.In the hydraulic system of excavators,the piston pump is an important power element.FMP112 piston pump developed by a company is used in the hydraulic system of excavator,but it is found that the pump will produce great noise,which will greatly affect the health and working state of excavator operators.Therefore,it is of great significance to identify the noise source of the piston pump,which can provide a basis for future noise reduction.This paper takes the noise of FMP112 piston pump as the research object,compares the noise source identification methods at home and abroad,and designs the noise and vibration test system of FMP112 piston pump combined with theoretical analysis.The noise and vibration characteristics of the pump were obtained by effective measurement of the test data,and the specific noise source and noise transmission path of the pump were identified by spectrum analysis and partial coherence analysis at speeds of 1100r/min,1400r/min,1660r/min,1700r/min and1900r/min at load pressures of 20 MPa and 24 MPa.The main research contents and conclusions of this paper are as follows:(1)This paper introduces the research background of the noise of the main pump of the excavator,the research status of the noise source identification method of the piston pump and the noise source at home and abroad,and makes a theoretical analysis of the noise source and the generating mechanism of the FMP112 piston pump.(2)Combined with the structure of the pump under test,the working principle of the pump was briefly analyzed,and the vibration fundamental frequency of the plunger pump was calculated,and the vibration frequency of each part of the pump at different rotating speeds was obtained.(3)The acoustic knowledge is briefly introduced,and the common test methods and signal analysis and processing methods are introduced.The noise and vibration test of FMP112 piston pump based on sound pressure method is designed.(4)Based on the test data,the influence of background noise on the pump noisewas distinguished,and the overall noise of the pump was analyzed.It was found that the overall noise of the pump under test gradually increased with the increase of rotating speed and load.Finally,the noise and vibration signals of the pump in each working condition are analyzed in terms of frequency spectrum,and the main characteristic frequency is identified based on the fundamental frequency calculation.The analysis shows that the reciprocating impact of the piston,backward flow of oil and the pulsation of the oil are the main noise sources.The noise caused by the vibration of the bearing and the rotation of the spindle is a secondary noise source.(5)Pump partial coherent computation model is established,to determine the pump partial coherent noise identification calculation steps,noise sources of the pump under the conditions of partial coherence calculation,accurate to identify the characteristic frequency of the specific source: when the motor speed of 1400r/min,the main structure of noise under low frequency band for bearing vibration and shaft vibration,through C point transfer;at other rotating speeds,the main structural noise at low frequencies is the vibration generated by the rotation of the spindle,and the air noise source is mainly the propagation of the oil pulsation noise in the air.At medium and high frequencies at various rotating speeds,the structural noise source is mainly the vibration generated by the reciprocating impact of the piston,which is mainly transmitted through A and B point. |
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