Study On The Output Flow Pulsation Control Of Hydraulic Pump And Its Application

As an important part of hydromechatronics technology, hydraulic transmission haslots of unique advantages so that it is widely used in industrial field. However, hydraulictransmission also has some problems which limit its development. Pressure pulsation isjust one of these problems to be solved.Many reasons could cause pressure pulsation in hydraulic system, and the outputflow pulsation of hydraulic pump is the chief reason. It is the source of pressurepulsation.In this paper, some methods are proposed to reduce the pressure pulsation inhydraulic system by reducing the output flow pulsation of hydraulic pump.Firstly, structures, theoretical output flows and internal leakages of two kinds ofcommon hydraulic pumps, axial piston pump and internal gear pump, are discussed tofigure out the regularity of actual output flow of these two kinds of hydraulic pumps.Secondly, the experiment principle and method of measuring the actual output flowof hydraulic pump are discussed. And experiment device is designed and made tocomplete the experiment of measuring the actual output flow of two certain hydraulicpumps. The experiment data is analysed to get the real regularity of actual output flowof these two kinds of hydraulic pumps.Thirdly, two methods of reducing the output flow pulsation of hydraulic pump areproposed according to the real regularity of actual output flow of these two kinds ofhydraulic pumps:(1) Using staggered phase parallel pumps. With this method, flow rate and pressurepulsation can be reduced effectively by staggering the wave crest and wave trough ofoutput flow of two same hydraulic pumps.(2) Using closed-loop servo control system. In this method, a servo motor drivesthe hydraulic pump and a pressure sensor measures the pressure of hydraulic system andgives a feedback, so a closed-loop servo control system is established. The servo motorprovides real time change of rotation rate of the pump in need so that the output flowrate and pressure is getting steadily. Because of the limit of response frequency of servomotor, this method can get a beneficial effect when used in a low speed range. Thischaracteristic is just right for improving worse flow rate and pressure pulsation at lowspeed and enlarges available speed range of hydraulic pump.After the methods are proposed, corresponding software and hardware are designedto test and verify the effect. And the experimental result proves that these methods areeffective and feasible.Finally, the two methods proposed above are combined and used on a certainhydraulic universal testing machine. The application effect proves that these methodsare success. In a word, in this paper the methods to reduce the output flow pulsation ofhydraulic pump are proposed and applicated in industrial production. It improves theavailable speed range of hydraulic pump and provides a new direction to solve theproblem of pressure pulsation in hydraulic system.