Variable-volume head

Abstract

Disclosed is a device that includes a natural-gas compression system having a natural-gas powered combustion engine, a compression cylinder configured to receive natural gas and output compressed natural gas, a piston disposed in the compression cylinder and configured to translate through the compression cylinder in response to mechanical power received from the natural-gas powered combustion engine, and a variable-volume head mounted to the compression cylinder and configured to vary a compressed volume of the compression cylinder. In some instances, the variable-volume head includes a head body, an adjustment screw rotatably coupled to the head body, a plug moveable in threaded engagement with the adjustment screw, and an anti-rotation device coupled to the plug, the head body, or both. The anti-rotation device may be configured to impede the plug from rotating relative to the head body as the adjustment screw rotates.

1 . A device, comprising:
 a natural-gas compression system, comprising:
 a natural-gas powered combustion engine, 
 a compression cylinder configured to receive natural gas and output compressed natural gas; 
 a piston disposed in the compression cylinder and configured to translate through the compression cylinder in response to mechanical power received from the natural-gas powered combustion engine; 
 a variable-volume head mounted to the compression cylinder and configured to vary a compressible volume of the compression cylinder, wherein the variable-volume head comprises:
 a head body; 
 an adjustment screw rotatably coupled to the head body; 
 a plug moveable in threaded engagement with the adjustment screw; and 
 an anti-rotation device coupled to the plug, the head body, or both, wherein the anti-rotation device is configured to impede the plug from rotating relative to the head body as the adjustment screw rotates. 
 
   
     
     
         2 . The device of  claim 1 , wherein the anti-rotation device comprises:
 a groove; and   a guide pin extending into the groove, wherein the guide pin extends between the plug and the variable-volume head.   
     
     
         3 . The device of  claim 1 , wherein the adjustment screw comprises:
 a first threaded portion extending into the plug; and   a second threaded portion through which the adjustment screw is rotatably coupled to the head body.   
     
     
         4 . The device of  claim 3 , wherein the first threaded portion and the second threaded portion are oppositely oriented such that one is right handed and the other is left handed. 
     
     
         5 . The device of  claim 3 , wherein the first threaded portion has a first thread pitch substantially larger than a second thread pitch of the second threaded portion. 
     
     
         6 . The device of  claim 5 , wherein the first threaded portion and the second threaded portion are oppositely oriented. 
     
     
         7 . A device, comprising:
 a variable-volume head, comprising:
 a moveable member configured to vary the size of a volume that houses a compressible fluid, wherein the moveable member comprises a first threaded aperture; 
 an adjustment screw having a first threaded portion mated with the first threaded aperture of the moveable member. 
   
     
     
         8 . The device of  claim 7 , wherein the adjustment screw comprises a second threaded portion. 
     
     
         9 . The device of  claim 8 , wherein the first threaded portion has first threads that are oriented in an opposite direction relative to second threads of the second threaded portion. 
     
     
         10 . The device of  claim 8 , wherein the first threaded portion has a first thread pitch that is substantially larger than a second thread pitch of the second threaded portion. 
     
     
         11 . The device of  claim 8 , comprising a head body coupled to the adjustment screw via the second threaded portion. 
     
     
         12 . The device of  claim 11 , comprising a collar having a second threaded aperture mated with the second threaded portion, wherein the head body is coupled to the adjustment screw via the collar. 
     
     
         13 . The device of  claim 7 , comprising an anti-rotation device configured to impede rotation of the moveable member and allow the moveable member to translate. 
     
     
         14 . The device of  claim 13 , wherein the anti-rotation device comprises a groove and a guide pin disposed in the groove. 
     
     
         15 . The device of  claim 7 , comprising a compressor coupled to the variable volume head. 
     
     
         16 . A method, comprising:
 rotating a member relative to a compressor through a first angular distance;   translating the member a first axial distance in response to rotating through the angular distance;   rotating the member relative to a plug through a second angular distance;   axially moving the plug the first axial distance plus a second axial distance determined by the second angular distance; and   changing a compressible volume of a compressor with the plug.   
     
     
         17 . The method of  claim 16 , wherein the first angular distance is generally equal to the second angular distance. 
     
     
         18 . The method of  claim 16 , wherein the first axial distance is substantially smaller than the second axial distance. 
     
     
         19 . The method of  claim 16 , comprising receiving torque from a tool interface. 
     
     
         20 . The method of  claim 16 , comprising biasing the plug away from or toward an interior of a cylinder of the compressor.