Analysis Of Attenuation Characteristics Of Hybrid Fluid Filter

Hydraulic system is gradually developing towards high pressure,high power and high speed.The small fluctuation of hydraulic oil pressure will have a great impact on the vibration and stability of hydraulic system.The periodic discharging mechanism of hydraulic pump determines that the flow pulsation will produce pressure pulsation when it meets the system impedance and propagates along the pipeline of the whole hydraulic system,which will cause fatigue or damage of the hydraulic pipeline system,reduce its reliability and bring huge risks.In order to attenuate the pressure pulsation in the hydraulic system,various pressure pulsation attenuators have been designed,such as Impedance,resistance and impedance compound constant pressure pulsation attenuator.But now most of the pressure pulsation attenuators have narrow attenuation frequency range,strong frequency selectivity and can not meet the requirements of broadband filtering.To solve this problem,this paper designs a hybrid fluid filter,which combines the filtering characteristics of H-type and K-type filters,and achieves the effect of broadband attenuation of pressure fluctuation.The main contents of this paper are as follows:?1?Combined with the respective filtering characteristics of H-type and K-type filters,a composite fluid filter is designed.Combining the dynamic characteristics of the hydraulic system piping with the actual working load,the equivalent of the filter is established by using the electro-hydraulic comparison modeling method.The circuit diagram analyzes the influence of the main structural parameters of the filter on the attenuation effect.Under the condition of ideal load or actual load,the attenuation effect of the filter on pressure pulsation under different load conditions is compared.The research results show that under the actual load condition,the low frequency is dominated by the H-type filter,and the high frequency is related to the K-type filter,which realizes the respective filtering characteristics of the H-type and K-type filters;in the case where other parameters are not changed,Appropriately increasing the length of the front pipe L_A is beneficial to the attenuation of the pressure pulsation of the filter;under ideal load conditions,the filter can also effectively attenuate when the frequency is about 200 Hz-250 Hz,but at a frequency of 450 Hz-900 Hz,The filter has no attenuation effect.?2?Under the condition of actual working load,a two-stage composite fluid filter is designed for the deficiency of the frequency range of the composite fluid filter.The equivalent circuit diagram of the filter is established and the two-stage composite fluid filter is analyzed.The effect of some structural parameters and the length of L_B11 on the attenuation effect.The simulation results show that the filtering performance of the two-stage composite fluid filter is better than that of the composite fluid filter.When the frequency is about 450Hz-717Hz,the fluid filter effectively widens the filtering range of the interval.?3?In order to verify the correctness of the model,the piston pump is used as the pulsation source,combined with the dynamic characteristics of the hydraulic system pipeline and the actual load,the mathematical model of the composite fluid filter in the time domain is established by using the power bonding diagram,and the research and analysis are carried out.The main structural parameters of the filter affect the attenuation of pressure pulsations.The simulation results show that under the condition of the same pulsating frequency in the frequency domain,the main structural parameters of the composite fluid filter affect the pressure pulsation attenuation curve and the curve change trend in the frequency domain has the same change.The trend,that is,the change trend is consistent,and it is verified that the equivalent circuit diagram established in the frequency domain and the analysis of the main structural parameters of the composite fluid filter have the correct effect on the pressure pulsation attenuation effect.