Patent Publication Number: US-2009229545-A1

Title: Crankshaft for integral gas compressor and internal combustion engine

Description:
BACKGROUND 
     Reciprocating gas compressors are well known in the art, and some are suitable for use in handling flammable gases such as natural gas. One type of gas compressor used in these applications is integral with an internal combustion engine. 
     Previously, the construction of an integral gas compressor and internal combustion engine included removing some of the engine components and replacing them with compressor components. For example, U.S. Pat. No. 2,133,769 to Jones discloses an engine-compressor unit with one side of a V-shaped engine, in this case a Ford V-8, being converted to an air compressor. In this apparatus, the engine head on one bank of cylinders is removed, along with the pistons and engine intake and exhaust valves, valve push rods and valve springs. A compressor head is installed on that bank of cylinders of the engine in place of the engine head, and compressor intake and exhaust valves are installed in the compressor head. The Jones apparatus is made from a flathead engine in which the valves are mounted in the engine block below the engine head, and the compressor head covers the existing openings through which the engine valve originally extended. In Jones, apparatus is designed for use with atmospheric air only, and does not address the problems involved with handling gases with inlet pressures above atmospheric pressure or gases which are flammable, such as natural gas. 
     An integral gas compressor and internal combustion engine designed for flammable gases and above atmospheric inlet pressures is disclosed in U.S. Pat. Nos. 4,961,891; 5,189,905; 5,203,680; and 5,267,843 to Waldrop, assigned to the assignee of the present invention. This compressor is shown constructed using a converted V-8 engine. The compressor head on this apparatus manifolds a plurality of inlet valves together. The engine for this compressor is a V-8 engine of a more modern overhead-valve type than the flathead of Jones. In this overhead-valve engine, the cylinder block, also sometimes referred to as the engine block, has a longitudinally extending port therethrough with a plurality of openings intersecting the port substantially perpendicular thereto. Engine valves are mounted on the engine head under a valve cover, and valve push rods are disposed in the openings in the cylinder block to engage valve rocker arms which in turn actuate the valves. The longitudinal port, also referred to as an oil gallery, provides a lubrication path from the engine oil pump to the valve push rods. When converting one side of an existing engine to a compressor, opposite ends of the longitudinal port and all of the intersecting openings have to be plugged. This not only adds to the cost of building the compressor but can also be a source of oil leaks if any of the plugs do not seal properly. Therefore, there is a need for a cylinder block where it is not necessary to plug ports or openings. U.S. patent application Ser. No. 11/247,108 published as US 2007-0079778A1 addresses such concerns. 
     An additional concern with the integral gas compressor and internal combustion engine is that it may run roughly, or unevenly, due to the configuration of the typical V-8 crankshaft normally used with such apparatus. This disclosure describes a crankshaft that creates a firing order that allows the apparatus to run smoothly. 
     SUMMARY 
     A cylinder block designed for use in an integral gas compressor and internal combustion engine uses a crankshaft that changes the normal firing order that would occur with a prior art crankshaft. The block comprises an engine portion defining an engine cylinder therein with a valve train opening defined adjacent to the engine cylinder and also comprises a compressor portion defining a compressor cylinder therein wherein the compressor portion may have no valve train opening. The valve train opening in the engine portion is adapted for receiving an engine valve train component therein. 
     The compressor cylinder and engine cylinder preferably form a V-shaped configuration. In one embodiment, the cylinder block has a V-8 configuration wherein the engine cylinder is one of four engine cylinders, the compressor cylinder is one of four compressor cylinders and the valve train opening is one of a plurality of valve train openings adjacent to the engine cylinders. 
     Stated in another way, the cylinder block comprises a first section with a plurality of cylinders defined therein and having a plurality of bosses integrally formed thereon and a second section with a plurality of cylinders defined therein and having a plurality of bosses integrally formed thereon. The bosses on one of the first and second sections are solid, and the bosses on the other of the first and second sections define valve train openings therein for receiving a portion of an engine valve train therein. Each of the cylinders on the one section are adapted for receiving a compressor piston therein, and each of the cylinders on the other section are adapted for receiving an engine piston therein. Preferably, the first and second sections form a V-shaped configuration, such as a V-8 configuration with four cylinders each. 
     The integral gas compressor and internal combustion engine apparatus comprises a cylinder block defining a set of compressor cylinders and a set of engine cylinders therein and further defining valve train openings adjacent to the set of engine cylinders only, a crankshaft rotatably disposed in the cylinder block, a compressor piston disposed in each of the compressor cylinders, an engine piston disposed in each of the engine cylinders, a connecting rod connecting each of the compressor and engine pistons to the crankshaft, a compressor head with compressor valves therein adjacent to the compressor cylinders, an engine head adapted for receiving engine valves therein adjacent to the engine cylinders, a cam rotatably disposed in the cylinder block, and an engine valve train including engine valves and engaging the cam, a portion of the engine valve train extending through the valve train openings. 
     Preferably, the portion of the valve train extending though the valve train openings comprises a plurality of valve push rods. 
     The cylinder block in the compressor further defines an oil gallery connectable to an engine oil pump and in communication with the valve train openings. The cylinder block may have a V-shaped configuration having a pair of banks, wherein the compressor cylinders are defined in one bank and the engine cylinders are defined in the other bank, and may be a V-8 configuration with four compressor cylinders and four engine cylinders. The valve train openings may be completely defined in the bank defining the engine cylinders. 
     The crankshaft used in the apparatus has four journals, two end journals and two intermediate journals. The two end journals are coaxial, and the two intermediate journals are coaxial. The crankshaft changes the firing order from that which would occur with a typical prior art V-8 crankshaft and causes the apparatus to run more evenly. 
     Numerous objects and advantages of the invention will become apparent as the following detailed description of the preferred embodiment is read in conjunction with the drawings illustrating such embodiment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  generally shows a compressor package of the type which utilizes the cylinder block for an integral gas compressor and internal combustion engine of the present invention. 
         FIG. 2  is a plan view of the compressor package of  FIG. 1 . 
         FIG. 3  is an end view of an integral gas compressor and internal combustion engine showing the cylinder block of the present invention. 
         FIG. 4  is a perspective view of the cylinder block. 
         FIG. 5  is a vertical cross section taken along lines  5 - 5  in  FIG. 4 . 
         FIG. 6  is a horizontal cross section taken along lines  6 - 6  in  FIG. 5 . 
         FIG. 7  is a prior V-8 crankshaft. 
         FIG. 8  is a prior art V-8 crankshaft with connecting rods mounted thereto. 
         FIG. 9  is a view of the crankshaft of the current invention. 
         FIG. 10  is a crankshaft of the current invention with connecting rods mounted thereto. 
         FIG. 11  is a representative view looking down at the engine and compressor cylinders. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, and more particularly to  FIG. 1 , an integral gas compressor and internal combustion engine apparatus which incorporates the crankshaft of the present invention is shown and generally designated by the numeral  10 . Compressor  10  is shown as a portion of a compressor package  12 . Integral gas compressor and internal combustion engine  10  will also be referred to herein as simply compressor apparatus  10 . 
     Compressor package  12  as illustrated is of a type particularly well adapted for use in recovering natural gas from a well, but may be used for other flammable gases or gases with elevated inlet pressures. The invention is not intended to be limited to the illustrated compressor package  12 .  FIGS. 1 and 2  have been greatly simplified to eliminate much of the piping and wiring associated with package  12 . The omitted items are known in the art and are not necessary for an understanding of the invention. 
     In a typical package  12 , such as that shown in  FIGS. 1 and 2 , compressor  10  is mounted on a skid or baseplate  14 . An inlet tank and liquid separator  18  is also attached to skid  14 . A valve  20  is in communication with tank  18  and is adapted for connection to the source of the gas to be compressed. In one embodiment, this gas would be natural gas from a wellhead (not shown), but compressor  10  and package  12  can be adapted to virtually any gas, and the invention is not intended to be limited to any particular application. 
     The top of tank  18  is connected to a compressor inlet manifold  82  mounted on a compressor head  24  on compressor  10  by a line  26 . That is, line  26  is an inlet or suction line for compressor  10 . 
     Positioned adjacent to tank  18  is a fuel vessel  28  which is adapted for connection to a fuel source, such as the natural gas wellhead. A line  30  connects fuel vessel  28  to carburetor  32  on the engine portion of compressor  10 . 
     An aftercooler  40  is mounted on skid  14  and used to cool gas discharged from compressor  10 . Aftercooler  40  is shown as a finned tube type with a cooling fan  42  associated therewith. Fan  42  may be driven by a drive shaft  44  extending from compressor  10 . Aftercooler  40  may include an engine jacket water-cooling section to cool the engine and compressor sections of compressor  10 . 
     A discharge line  46  connects the outlet of compressor  10  with aftercooler  40 . An aftercooler outlet line  48  extends from aftercooler  40 . 
     An electrical control panel  50  for controlling the apparatus may be positioned on skid  14 . Control panel  50  is of a kind generally known in the art, and the connections thereto are omitted for clarity. 
     Compressor  10  is constructed using the general layout of a known internal combustion engine, such as, but not limited to, a 460 cubic inch Ford V-8 engine. The general V-shaped configuration of compressor  10  is shown in  FIG. 3 . Compressor  10  comprises a cylinder block  60  specifically designed to be used as a compressor on one side or bank and as an engine on the other side or bank. While the original engine cylinder block as used in some prior art compressors may be used, the preferred cylinder block is as described herein, and in U.S. patent application Ser. No. 11/247,108, assigned to the assignee hereof. 
     Below cylinder block  60  is an oil pan  64 . At the upper end of cylinder block  60  is an engine intake manifold  66 . Oil pan  64  and engine intake manifold  66  are standard components of the original Ford or other engine. A known carburetor  68  and air cleaner  70  are mounted on engine intake manifold  66 . 
     Connected to cylinder block  60  on the right bank of cylinders  71 , as viewed in  FIG. 3 , is a standard engine head  72  with a valve cover  74  thereon. An exhaust manifold  76  carries away the exhaust gases of the engine. This right side of compressor  10  remains basically a standard engine and includes valve train  78 , as will be further discussed herein, and other engine components which are not illustrated, such as spark plugs, wiring, etc. 
     The left side of compressor  10 , as viewed in  FIG. 3 , is used for gas compression. Compressor head  24  is attached to cylinder block  60  on the left bank of cylinders  81 . Connected to compressor head  24  is compressor inlet manifold  82 . Attached to compressor inlet manifold  82  is a flange to which inlet line  26  is connected. Compressor head  24 , compressor inlet manifold  82  and flange  83  are of the kind described in the above-referenced patents to Waldrop. 
     Standard engine pistons  84  are reciprocably disposed in the cylinders  71  on the right bank of cylinder block  60 . Thus, cylinders  71  may be described as engine cylinders  71 . The engine pistons are connected to crankshaft  86  by connecting rods  88 . Engine pistons  84  and connecting rods  88  are the original components of the engine on which compressor  10  is based. Crankshaft  86  is not the original, or a prior art V-8 crankshaft, but rather is a novel crankshaft as described herein for use with the V-8 cylinder block. 
     A plurality of compressor pistons  90  are reciprocably disposed in cylinders  81  in the left bank of cylinder block  60 . Thus, cylinders  81  may be described as compressor cylinders  81 . Each compressor piston  90  is connected to crankshaft  86  by additional connecting rods  92 . Compressor pistons  90  are preferably specifically designed for gas compression, but connecting rods  92  may be the same as connecting rods  88  on the engine side of compressor  10 . It is understood that compressor head  24  will have a plurality of compressor valves disposed therein associated with compressor pistons  90 . 
     A plurality of bosses  93  and  95  are integrally cast into cylinder block  60  adjacent to engine cylinders  71  and compressor cylinders  81 , respectively. 
     Valve train  78  of the engine side of compressor  10  includes a rotating cam  94  which engages a plurality of push rods  96 . Push rods  96  in turn engage corresponding valve rocker arms  98  which actuate engine valves  100  in each cylinder in a manner known in the art. Valve springs are not shown. 
     Referring to  FIGS. 3-6 , each push rod  96  is movably disposed in a corresponding push rod opening  102  machined in each boss  93  of cylinder block  60 . A longitudinally extending oil port or gallery  104  intersects openings  102  and thus is in communication therewith. Engine lubricating oil is pumped by the engine oil pump (not shown) to port  104  and thus to openings  102  in a manner known in the art. 
     In some integral gas compressor and internal combustion apparatus made from previously existing engines, there are identical openings  102  in bosses  95  and a port  104  on the compressor side, all of the ports and openings being in communication with one another by crossover passages (not shown) in an enlarged section  105 . Because there is no valve train, and thus no push rods, on the compressor side, it will be seen by those skilled in the art that the port and openings in previously-existing engines will result in an open path for oil to flow out onto the cylinder block if the port and openings are not closed. Not only does this cause a loss of oil pressure for the engine, the presence of oil on the compressor side is undesirable. Therefore, in previous apparatus of this type, port  104  and openings  102  have been plugged on the compressor side. This adds to the material and labor costs of the equipment and also requires leak testing. 
     Cylinder block  60  is preferably only machined for the engine valve train on the engine side of the block. That is, bosses  95  and enlarged section  105  are left solid and unmachined. The compressor side of cylinder block  60 , as seen on the left sides of FIGS.  3 - 6 , is not machined at all. That is, on cylinder block  60 , there is a solid portion  110 , and the block is designed to fully isolate oil in the engine side from the compressor side. Thus, there is no need to plug any port or openings to prevent the problems associated with prior compressors made from existing engine blocks. 
       FIGS. 7 and 8  depict a typical prior art crankshaft  150  that would be used in a V-8 cylinder block. Crankshaft  150  has first, second, third and fourth journal locations  152 ,  154 ,  156  and  158 , respectively. Journals  152  and  158  may be referred to as end journals, and journals  154  and  156  may be referred to as intermediate journals. As viewed in  FIG. 7 , journal  154  is positioned 90° clockwise from journal  152 , journal  156  is positioned 270° clockwise from journal  152 , and journal  158  is positioned 180° clockwise from journal  152 . A pair of connecting rods  160  of a type known in the art would be mounted at each journal location to connect compressor pistons  90  and engine pistons  84  to crankshaft  150 . Rotation of the crankshaft  150  will cause compressor pistons  90  and engine pistons  84  to move in the engine and compressor cylinders  71  and  81 , respectively. 
     Referring now to  FIG. 11 , the engine and compression cylinders are represented by the circles identified with the numbers 1 through 8. During operation, the firing order for a V-8 engine would be 1-5-4-2-6-3-7-8 with prior art crankshaft  150 . It is understood that the firing order refers to the normal operation of an engine in which a spark plug fires, causing a power stroke of an engine piston. This is what is meant when reference is made to the engine or an engine cylinder firing. A V-8 that has been converted to a compressor will therefore have “dead spots” in which the engine side does not fire. For example, when engine cylinder  1  fires, the crankshaft will rotate 90°, but instead of firing again, compressor piston in compressor cylinder  5  moves. Additional 90° rotation causes engine cylinder  4  to fire, and after an additional 90° of rotation, engine cylinder  2  fires. An additional 90° of rotation then causes movement of compressor piston in compressor cylinder  6 , then after 90° engine cylinder  3  fires, then another 90° and the compressor in compressor cylinder  7  moves. An additional 90° of rotation causes the compressor piston in compressor cylinder  8  to move, and 90° further rotation causes engine cylinder  1  to fire again. Thus, with the prior art V-8 crankshaft, 270° of crankshaft rotation can occur between the times when the engine side fires. For example, after engine cylinder  3  fires, crankshaft  150  will rotate 270° before another engine cylinder fires, in this case engine cylinder  1 . As such, when a V-8 engine is converted to a compressor, the apparatus can run rough because of the intermittent and uneven firing on the engine side. 
     To create a smoother running compressor, crankshaft  86  is used. Crankshaft  86  is similar to a crankshaft used in 4-cylinder engines, modified so that two connecting rods can be attached at each journal location. Crankshaft  86  has four journals, namely, first, second, third and fourth journals  162 ,  164 ,  166  and  168 . Journals  162  and  168  may be referred to as end journals, while journals  164  and  166  may be referred to as intermediate journals. Crankshaft  86  has first and second ends  170  and  172  and is mounted in cylinder block  60  in a manner known in the art. 
     First and fourth journals  162  and  168  are coaxial, and thus have common longitudinal axis  174 , second and third journals  164  and  166  are coaxial and have longitudinal axis  176 . Ends  170  and  172 , which may be referred to as mounting ends  170  and  172  have a longitudinal axis  178 . Longitudinal axes  174 ,  176  and  178  lie in a common plane represented by line  180  in  FIG. 3 . As viewed in  FIG. 9 , longitudinal axis  174  is positioned above longitudinal axis  178 , and longitudinal axis  176  is positioned below longitudinal axis  178 . First and fourth journals  162  and  168  are, as viewed in  FIGS. 9 and 10 , above journals  164  and  166 . Considering longitudinal axis  178  as a center, journals  164  and  166  are positioned 180° from journals  162  and  168 . 
     Crankshaft  86  may have counterweights  182  of a type known in the art mounted thereto. As shown in  FIG. 10 , counterweights  182  may include four pairs of counterweights, namely, first, second, third and fourth pairs  184 ,  186 ,  188  and  190 . Connecting rods  88  and  92 , which may be connecting rods of a type generally used with a V-8, are mounted to crankshaft  86 . Each journal  162 ,  164 ,  166  and  168  has two connecting rods mounted thereto, one connecting rod  88  and one connecting rod  92 . Eight connecting rods, which may be referred to as connecting rods  194 ,  196 ,  198 ,  200 ,  202 ,  204 ,  206  and  208 , are shown in  FIG. 10 . Connecting rods  194  and  196  are mounted to journal  162 . Connecting rods  198  and  200  are connected to journal  164 . Connecting rods  202  and  204  are mounted to journal  166 . Connecting rods  206  and  208  are mounted to journal  168 . 
     Each of connecting rods  92  is connected to either an engine piston  84  or compressor piston  90 . For example, connecting rods  88  may comprise connecting rods  194 ,  198 ,  202  and  206  which may each be connected to an engine piston  84  which, in the schematic of  FIG. 11 , corresponds to engine pistons in the engine cylinders numbered 1, 2, 3, and 4. Connecting rods  92  may comprise connecting rods  196 ,  200 ,  204  and  208  which are connected to compressor pistons  90  which correspond to the numbers 5, 6, 7 and 8 in  FIG. 11 . 
     Compressor  10  runs more evenly and smoothly with crankshaft  86  than with a typical prior art V-8 crankshaft  150 . 
     The engine cylinders  81  in the engine side of compressor  10  will fire every half rotation, or every 180° of rotation of crankshaft  86  so that there will be a power stroke on the engine side every half rotation of the crankshaft. Thus, the engine side will fire four times every 720° of rotation, just as with a typical crankshaft, but will run more evenly. The firing order on the engine side will be 1-3-4-2 and at any given time, two engine pistons  84  will cycle up and two will cycle down. 
     Because the engine side fires every 180° of rotation of crankshaft  86 , there is no unevenness to the running of compressor  10 . Each compressor piston  90  will go through an intake/exhaust cycle with each full rotation of crankshaft  86 , and, as with engine pistons  84 , two compressor pistons  90  will cycle up and two will cycle down at any given time. The compressor  10 , because the engine side fires more evenly than with the prior art crankshaft, will run more efficiently, in that it will require less fuel, will produce fewer emissions, higher torque and create less wear. The compressor  10  will run more smoothly with less vibration, which will reduce maintenance costs. 
     While cylinder block  60  has been shown in the drawings with the engine side or section on the right and the compressor side or section on the left, these could be reversed by reversing the machining. That is, compressor  10  could be made with the engine side or section on the left and the compressor side or section on the right. 
     It will be seen, therefore, that the cylinder block and crankshaft for integral gas compressor and internal combustion engine of the present invention is well adapted to carry out the ends and advantages mentioned as well as those inherent therein. While a presently preferred embodiment of the apparatus has been shown for the purposes of this disclosure, numerous changes in the arrangement and construction of the parts may be made by those skilled in the art. All such changes are encompassed within the scope and spirit of the appended claims.