Design and Manufacturing of a Crankshaft-Free Compressor

The conventional crankshaft-driven reciprocating compressors inherently suffer from insufficient torque at the end of the compression due to their design. This study aims at designing and experimentally testing a crankshaft-free compressor in which the compression process is achieved by driving the pistons over an elliptical ring in order to convert the rotary motion directly into reciprocating motion of the pistons. The proposed mechanism allows the forces acting on the pistons to be aligned with the piston axis which results in improved mechanical efficiency and torque characteristics. Thermodynamic analysis was performed in order to determine the operating parameters and MATLAB/Simulink was used to evaluate the dynamic behavior of the mechanism. Additionally, the structural integrity and vibration characteristics of the system were investigated by means of finite element and modal analysis via ANSYS. Based on the obtained results, proper materials for each of the components were selected and the compressor was manufactured and experimentally tested under laboratory conditions. Experimental data showed that with an input power of 1 kW, the crankshaft-free orbital compressor was capable of achieving a delivery pressure of 800 kPa (absolute) with a volumetric flow rate of 200 L/min at 1000 rpm. It was concluded that the designed compressor can be considered as a potential alternative to conventional reciprocating compressors in industrial applications.