Patent ID: 8430646
Filing Date: 2013-04-30
Classification: F04B

Abstract:
1. In a reciprocating compressor, a device for varying the clearance volume of a variable volume clearance pocket, the device comprising: a) a main housing having a gear end and a piston end, and a threaded bore having first threads; b) a gear housing mounted to the gear end of the main housing, the gear housing including a drive gear; c) a head mounted to the piston end of the main housing and adapted to sealably fit within the outer end of a reciprocating compressor cylinder, the compressor cylinder including a compressor piston and a variable volume clearance pocket, the clearance pocket formed between the compressor piston and the outer end of the compressor cylinder; d) a clearancing piston located within the head of the device and adapted to be movable therein, movement of the clearancing piston operable to vary the clearance volume within the compressor cylinder; e) a threaded stem having a drive engagement end and a piston end, the drive engagement end of the threaded stem having a bore therein, the piston end of the threaded stem rigidly connected to the clearancing piston, wherein the threaded stem is supported and aligned by a sleeve bearing, the threaded stem having second threads on the outer diameter of the threaded stem that engage the first threads of the threaded bore, wherein rotation of the threaded stem and the rigidly connected piston causes the second threads to rotate in the first threads, thereby axially withdrawing or advancing the piston within the head; f) a telescoping drive shaft having a gear end and a drive engagement end and adapted to be turned by the drive gear, the gear end of the drive shaft attached to the drive gear, the drive engagement end of the drive shaft adapted to drivably engage the bore in the drive engagement end of the threaded stem to rotate the threaded stem and the rigidly connected piston, wherein the drive engagement end of the drive shaft axially slides into or retreats out of the drive engagement end of the threaded stem as the drive shaft is turned by the drive gear thereby causing the threaded stem to rotate; g) a pressure amplifier configured to amplify pressure from a pressurized fluid source; and h) a pressure-actuated jam nut for biasing the threaded stem in a static position and for unbiasing the threaded stem to allow movement thereof, the jam nut including at least one pressure disc defining a sealed interior region of the jam nut, the interior region configured to accept liquid pressurized by the pressure amplifier, wherein application of the pressurized liquid in the interior region causes the jam nut to lock the threaded stem in a fixed position, wherein when the jam nut is unbiased the threaded stem and the clearancing piston can be rotated to advance axially outward and inward within in the head, and wherein movement of the clearancing piston within the head allows the volume of the clearance pocket to be varied in a controlled manner.