Compressed gas engine

Abstract

A compressed gas engine is provided. The compressed gas engine may include a first crankshaft, a first set of piston assemblies, a second set of piston assemblies, and a first valve assembly. The first set of piston assemblies may be coupled to the first crankshaft and comprise a first piston assembly having a first diameter and a second piston assembly having a second diameter. The second set of piston assemblies may be operatively coupled to the first crankshaft and comprise a third piston assembly having the first diameter and a fourth piston assembly having the second diameter. The second set of piston assemblies may be positioned on the crankshaft opposite the first set of piston assemblies such that the piston assemblies of the first set of piston assemblies and the piston assemblies of the second set of piston assemblies having the same diameter are aligned.

What is claimed is: 
     
         1 . A compressed gas engine comprising:
 a first engine module comprising:
 a first crankshaft; 
 a first set of piston assemblies operatively coupled to the first crankshaft and comprising a first piston assembly having a first diameter and a second piston assembly having a second diameter; 
 a second set of piston assemblies operatively coupled to the first crankshaft and comprising a third piston assembly having the first diameter and a fourth piston assembly having the second diameter, the second set of piston assemblies positioned on the crankshaft opposite the first set of piston assemblies such that the piston assemblies of the first set of piston assemblies and the piston assemblies of the second set of piston assemblies having the same diameter are aligned; and 
 a first valve assembly fluidly coupled to the first set of pistons and the second set of pistons and configured to control a flow of compressed air through the first engine module; and 
   wherein:
 an open-side cavity of the first piston assembly is fluidly coupled to and receives compressed air from a compressed air source; and 
 a rod-side cavity of the second piston assembly is fluidly coupled to and receives partially expanded compressed air from a rod-side cavity of the first piston assembly. 
   
     
     
         2 . The compressed air engine of  claim 1 , wherein the second diameter is larger than the first diameter. 
     
     
         3 . The compressed air engine of  claim 1 , wherein adjacent piston assemblies within the same set of piston assemblies are connected to the crankshaft at points that are radially offset from each other by 180 degrees. 
     
     
         4 . The compressed air engine of  claim 1 , wherein the first valve assembly comprises at least one of plurality of spool valves or a plurality of solenoid valves. 
     
     
         5 . The compressed gas engine of  claim 1 , wherein:
 the rod-side cavity of the first piston assembly is fluidly coupled to and receives compressed air from the compressed air source; and   an open-side cavity of the second piston assembly is fluidly coupled to and receives partially expanded compressed air from the open-side cavity of the first piston assembly.   
     
     
         6 . The compressed gas engine of  claim 5 , wherein:
 an open-side cavity of the third piston assembly is fluidly coupled to and receives compressed air from the compressed air source; and   a rod-side cavity of the fourth piston assembly is fluidly coupled to and receives partially expanded compressed air from a rod-side cavity of the third piston assembly.   
     
     
         7 . The compressed gas engine of  claim 6 , wherein:
 the rod-side cavity of the third piston assembly is fluidly coupled to and receives compressed air from the compressed air source; and   an open-side cavity of the fourth piston assembly is fluidly coupled to and receives partially expanded compressed air from the open-side cavity of the third piston assembly.   
     
     
         8 . The compressed gas engine of  claim 5 , wherein:
 the rod-side cavity of the second piston assembly is fluidly coupled to and receives compressed air from the compressed air source; and   the open-side cavity of the second piston assembly is fluidly coupled to and receives compressed air from the compressed air source.   
     
     
         9 . The compressed gas engine of  claim 1 , wherein:
 the first set of piston assemblies further comprises a fifth piston assembly having a third diameter; and   the second set of piston assemblies comprises a sixth piston assembly having the third diameter.   
     
     
         10 . The compressed gas engine of  claim 9 , wherein a rod-side cavity of the fifth piston assembly is fluidly coupled to and receives further expanded compressed air from the rod-side cavity of the second piston assembly. 
     
     
         11 . The compressed air engine of  claim 10 , wherein the rod-side cavity of the fifth piston assembly is fluidly coupled to and exhausts decompressed air to a decompressed air container. 
     
     
         12 . The compressed gas engine of  claim 9 , wherein an open-side cavity of the fifth piston assembly is fluidly coupled to and receives further expanded compressed air from an open-side cavity of the second piston assembly. 
     
     
         13 . The compressed air engine of  claim 12 , wherein the open-side cavity of the fifth piston assembly is fluidly coupled to and exhausts decompressed air to a decompressed air container 
     
     
         14 . The compressed gas engine of  claim 1 , further comprising a second engine module comprising:
 a second crankshaft operatively coupled to the first crankshaft; and   a third set of piston assemblies operatively coupled to the second crankshaft and comprising a fifth piston assembly having the first diameter and a sixth piston assembly having the second diameter;   a fourth set of piston assemblies operatively coupled to the second crankshaft and comprising a seventh piston assembly having the first diameter and an eighth piston assembly having the second diameter, the fourth set of piston assemblies positioned on the crankshaft opposite the third set of piston assemblies such that the piston assemblies of the third set of piston assemblies and the piston assemblies of the fourth set of piston assemblies having the same diameter are aligned; and   a second valve assembly valve assembly fluidly coupled to the third set of pistons and the fourth set of pistons, and configured to control a flow of compressed air through the second engine module.   
     
     
         15 . The compressed gas engine of  claim 14 , wherein:
 adjacent piston assemblies within the same set of piston assemblies are connected to the respective crankshaft at points that are radially offset from each other by 180 degrees; and   the piston assemblies of the first and the second sets of piston assemblies are connected to the first crankshaft at points that are radially offset by 90 degrees from connection points between the second crankshaft and the piston assemblies of the third and the fourth sets of piston assemblies.   
     
     
         16 . A method of operating a compressed gas engine, the method comprising:
 flowing compressed gas from a compressed gas source into a rod-side cavity of a first piston assembly of a first set of piston assemblies operatively coupled to a crankshaft, the first piston assembly having a first diameter;   flowing compressed gas from the compressed gas source into an open-side cavity of a second piston assembly of a second set of piston assemblies operatively coupled to the crankshaft and opposite the first set of piston assemblies, the second piston assembly having the first diameter and being aligned with the first piston assembly;   forcing partially expanded compressed gas to flow from an open-side cavity of the first piston assembly into an open-side cavity of a third piston assembly of the first set of piston assemblies, the third piston assembly having a second diameter; and   forcing partially expanded compressed gas to flow from a rod-side cavity of the second piston assembly into a rod-side cavity of a fourth piston assembly of the second set of piston assemblies, the fourth piston assembly having the second diameter and being aligned with the third piston assembly.   
     
     
         17 . The method of  claim 16 , wherein the second diameter is larger than the first diameter. 
     
     
         18 . The method of  claim 16 , further comprising:
 flowing compressed gas from the compressed gas source into the open-side cavity of the first piston assembly;   flowing compressed gas from the compressed gas source into the rod-side cavity of the second piston assembly;   forcing partially expanded compressed gas to flow from the rod-side cavity of the first piston assembly into a rod-side cavity of the third piston assembly; and   forcing partially expanded compressed gas to flow from the open-side cavity of the second piston assembly into an open-side cavity of the fourth piston assembly.   
     
     
         19 . The method of  claim 18 , wherein:
 the first set of piston assemblies further comprises a fifth piston assembly having a third diameter;   the second set of piston assemblies further comprises a sixth piston assembly having the third diameter and being aligned with the fifth piston assembly;   the third diameter is greater than the second diameter;   the second diameter is greater than the first diameter; and   the method further comprises:
 forcing further expanded compressed gas to flow from the open-side cavity of the third piston assembly into an open-side cavity of the fifth piston assembly; and 
 forcing further expanded compressed gas to flow from the rod-side cavity of the fourth piston assembly into a rod-side cavity of the sixth piston assembly. 
   
     
     
         20 . The method of  claim 19 , further comprising:
 forcing further expanded compressed gas to flow from the rod-side cavity of the third piston assembly into a rod-side cavity of the fifth piston assembly; and   forcing further expanded compressed gas to flow from the open-side cavity of the fourth piston assembly into an open-side cavity of the sixth piston assembly.