Parameters affecting oil film formation between top of vane and cylinder of multiple vane type compressor's

Effect of parameters affecting oil film formation on the top of vane of multiple vane type compressor was studied using the compressor equipped with an electrical insulating circuit. Experiments were conducted with polyalkylene glycol by varying the cooling conditions. The extent of oil film formation was evaluated as the separation degree (SD) defined by the percentage of the contact potential to the applied voltage between vane and cylinder. In a cooling cycle, SD was higher in the suction period than in compression period. When examining the effect of operating conditions, an increase in suction superheat increased an average separation degree (ASD) probably because of viscosity enhancement of refrigerating oil through reduction of refrigerant gas solubility. Meanwhile, ASD increased with increasing rotational speed and decreasing discharge pressure. Such oil film behaviour may be caused by pushing the vane against the cylinder, which is brought about by an increase in friction between side of vane and rotor groove. Finally, the wear test using real gas heat pump system under the operating conditions corresponding to low ASD. As a result, the wear amount of vane was significantly larger at lower rotational speeds and higher suction pressures.