Development and research of two-cylinder multi-stage pumping hydraulic drive of technological machines

Abstract

A five-stage two-cylinder pumping gear–multiplier hydraulic drive based on a simple dual gearbox and a dual block gearbox - multiplier is presented in the article. The gearbox consists of an input and two equal output (metering) cylinders and provides a gear stage (the speed and pressure of the pumps increases) at idle. The block reducer–multiplier consists of an input and two pairs (equal in a pair and unequal between pairs) of output cylinders and provides a reducer and two multipliers (the speed and pressure of pumps decreases) during the working stroke. The operation mode of the multiplier gearbox is provided by a combination of output cylinders supplying fluid to the power cylinders by switching part of them to drain. These four stages are combined with the stage of liquid supply to the power cylinders through the flow divider (pump stage). It is advisable to use a multi-stage drive with a smoothly increasing load on the entire value of the working stroke (operation of precipitation, extraction). The analysis is performed of a sequential combination of five stages (gear at idle, gear, pumping and two multipliers at working stroke) for a linearly increasing power load, which is determined by the pressure at the beginning of P₀ and the maximum at the end of the working stroke P_max. The analysis was performed under the condition of equality of pressure and pump power by stages and the condition of equality of the forward running time of comparable (simple and developed) drives. The ratio of pump capacities is estimated. The dependences of the main parameters of the developed drive, reduction and multiplication coefficients are obtained. With the accepted initial data, it is possible to reduce the pressure and power of the pumps by 34-40% (as compared with a simple hydraulic drive). In the ideal case of full use of pump power, this reduction is 39,5 – 46%. The next version of the drive, executed only on the basis of a dual block multiplier gearbox, provides four stages. The analysis of the sequential combination of gear, pump and two multiplier stages is performed. Herewith, the gear stage covers the idling and the initial part of the working stroke. With comparable initial data, this option provides a reduction in pressure and pump power by 30 – 34%. This is 4-6% less compared to the five-speed drive.