Multipurpose expanding machine

Abstract

At present the Sibkriotekhnika Joint-Stock Company (AO), Kompressor Scientific ,, Production Association, Kompressory BS NPTs, and a number of other organization produce compressors with low capacity in vertical, Y-shaped, and W-shaped versions intended for use in air conditioning, medicine, in transport and other branches of the economy [i]. A distint, uishing feature of these machines is their reliable and economical operation without lubrication, not only of the piston t, "oups but also of elements of the motive mechanism. They are therefore promising elements in designing multipurpose expanding machines whose application is most useful as decompressors, pneumatic motors, or independent, ecologically safe decompressor and compressor plants.The production of such machines envisages the use of a single unified compressor base which enables the producing enterprise with minimal production costs and within a short time to broaden the assormaent of products.The substance of the technical solution will be illustrated on the example of a separate series of multi-row piston engines whose design diagram is shown in Fig. 1.Piston 1 provided with seals or packing rings carries out a reciprocating motion without lubrication in cylinder 2 which on its periphery has the composite chamber 3 (pressure and temperature of the emerging gas is Pt', Tf, respectively). On the end face of the cylinder there are one or several single-type normally open self-acting inlet valves 4 whose shutting element moves within the range 0 < h < hva. The working gas (air) with the initial parameters Pi, Ti is fed to the inlet chamber 5 from the pneumatic mains of the enterprise or from a compressor stage of the plant itself.The cycle of the multipurpose expanding machine (MPEM) is presented in Fig. 2. The theoretical decompressor cycle 1-2-3-4-5-1 intended for obtaining the required final temperature of the gas Tf upon its expansion within the pressure range Pi-Pf is basic, for ensuring the mass flow rate of the gas m and the refrigerating power Q = Cpffa(T/-Tf), where cp is the heat capacity of the gas. In this case, when the piston moves from upper dead center (UDC) to the side of the shaft, the cylinder is filled with fresh gas via the open inlet valve (processes 1-2), and this is accompanied by an increase of the pressure gradient Ap, = Pi --Pc('P) that is due to the change of the instantaneous speed of the piston. At point 2 the gas force Fg, proportional to Ap2, exceeds the force of the valve spring Fsp, and in consequence the valve is automatically closed and the working chamber becomes closed, i.e., it is isolated from the inlet and outlet chambers. Further movement of the piston on the section 2-3 (the process of expansion) increases the volume of the working chamber, the pressure in it decreases from P2 to P3 with the corresponding lowering of the temperature. At point 3 the moving piston uncovers the exhaust windows 6 (see Fig. I) in the lateral surface of the cylinder in the zone of the lower dead center (LDC), and that leads to an abr...