Piston ring subassembly, angulating piston assembly and method of making same

摘要

An angulating piston assembly for a vehicle air conditioning system compressor comprises a composite piston including a metal rod having a ball at a proximal end and a plastic head at a distal end. A piston ring subassembly is operatively received about the periphery of the plastic piston head. The subassembly is characterized by a rigid support collar molded into the piston head and a piston ring of low friction material stretched and snugly received over the collar. An integral molded lip on the piston head and an outwardly projecting skirt on the support collar maintain the piston ring in position. An inwardly projecting flange is provided on the support collar and molded into the plastic piston head to provide a lock to prevent relative axial movement between the support collar and the piston head. A method of forming and assembling an angulating piston assembly includes the steps of: 1) mounting the piston ring on the rigid support collar; 2) placing the piston ring subassembly into a mold cavity; 3) positioning a distal end of a piston rod to extend into the mold cavity; 4) closing the mold cavity; 5) injecting molten plastic into the cavity to form the piston head; and 6) separating the mold cavity and removing the assembly.