A NOVEL TORQUE AMPLIFIER USING ALTERNATING FLOW HYDRAULICS AND ORBITAL ROTARY PISTON HYDRAULIC MOTOR PRINCIPLES-DESIGN AND PERFORMANCE

Abstract

The kinematic design methodology of a proposed hydrostatic machine [1] which comprises of (i) multi-piston pump with each chamber connected to corresponding chamber, with flexible or rigid piping, of an orbital rotary piston (ORBIT**) motor, (ii) a charge pump to compensate leakage and (iii) necessary circuit and valves, is presented. It works on the principles of alternating flow hydraulics (AFH) and hydrostatic transmission (HST) with Orbital rotary piston machines (ROPIMA). Earlier AFH-HST systems with cylindrical piston pump and motor, having transmission ratio of 1: 1, exhibited high efficiency in comparison to the DC HST of same capacity, as there is less loss due to the absence of flow distributor valve [2, 3]. Torque amplification is a unique additional advantageous feature of the proposed machine. The transmission ratio i.e., torque amplification or speed reduction ratio equals to the number of phases (piston) or one less depending upon the kinematic arrangement. A prototype is made and some aspects of performances are studied. It's possible application ranges from reduction unit in general to the articulated joint such as robot wrist actuator etc.