Abstract:
A reciprocating compressor barrel frame comprising a continuous curved wall having an inner surface and an outer surface. A housing is formed by the inner surface of the curved wall. A pair cross head shoe supports extend from the outer surface of said curved wall in opposite directions perpendicular to said housing. A plurality of bearing support members are disposed within the housing and supported by the curved wall. The bearing support members are arranged so as to support a crankshaft disposed within the housing. A base flange is connected to the curved wall and is operable to attach to a structure that will support the frame.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     Not Applicable.  
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0002]     Not Applicable.  
       BACKGROUND  
       [0003]     The present invention relates generally to reciprocating compressors. More particularly, the present invention relates to horizontally-opposed reciprocating compressors. Still more particularly, the present invention relates to the structural frame that supports the crankshaft of a horizontally opposed reciprocating compressor.  
         [0004]     Reciprocating compressors are positive-displacement pumps that pressurize a fluid by moving, or stroking, a piston axially within a cylinder. In horizontally-opposed reciprocating compressors, the pistons are connected, via cross heads and connecting rods, to a crankshaft that is rotated by an external power source. The pistons are positioned horizontally and arranged in pairs opposed at different planes across the crankshaft. In conventional applications, the crankshaft is supported within a frame that supports the reciprocating loads, coupled moments, and torque on the crankshaft.  
         [0005]     Most standard frames have a generally rectangular cross-section with vertical walls cantilevered from a heavy base. In order to minimize flexion and distortion of the vertical walls, the walls are generally very thick and interconnected at their tops by a plurality of high-strength tie bars. These tie bars must be made to very tight tolerances as any variations in length can have a major impact on the assembly of the tie bars. Further, as the capacity, speed, and pressure of a compressor increases, the size and weight of the frame also increases in order to manage the increased reciprocating loads, coupled moments, and torque.  
         [0006]     Thus, there remains a need to develop methods and apparatus for supporting reciprocating machinery, which overcome some of the foregoing difficulties while providing more advantageous overall results.  
       SUMMARY OF THE PREFERRED EMBODIMENTS  
       [0007]     The embodiments of the present invention are directed toward methods and apparatus for a reciprocating compressor barrel frame comprising a continuous curved wall having an inner surface and an outer surface. A housing is formed by the inner surface of the curved wall. A pair cross head shoe supports extend from the outer surface of said curved wall in opposite directions perpendicular to said housing. A plurality of bearing support members are disposed within the housing and supported by the curved wall. The bearing support members are arranged so as to support a crankshaft disposed within the housing. A base flange is connected to the curved wall and is operable to attach to a structure that will support the frame.  
         [0008]     In certain embodiments, a reciprocating compressor comprises a crankshaft and a plurality of cross heads coupled to the crankshaft via connecting rods. The compressor also comprises a frame comprising a continuously curved wall that encloses the crankshaft that is rotatably mounted within the frame. A plurality of cross head shoe supports extend from and are formed integral to the curved wall of the frame. Each cross head is supported by cross head shoes that are removably connected to the cross head shoe supports. A plurality of bearing support members are disposed within the housing and are supported by the curved wall. A plurality of bearings are disposed between the crankshaft and the plurality of bearing support members. A lubricant sump is disposed within the housing and arranged so as to lubricate the crankshaft.  
         [0009]     Thus, the present invention comprises a combination of features and advantages that enable it to overcome various problems of prior devices. The various characteristics described above, as well as other features, will be readily apparent to those skilled in the art upon reading the following detailed description of the preferred embodiments of the invention, and by referring to the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     For a more detailed description of the preferred embodiment of the present invention, reference will now be made to the accompanying drawings, wherein:  
         [0011]      FIG. 1  is a view of a reciprocating compressor including a frame constructed in accordance with embodiments of the invention;  
         [0012]      FIG. 2  is a partial sectional end view of a reciprocating compressor including a frame constructed in accordance with embodiments of the invention;  
         [0013]      FIG. 3  is an partial sectional isometric view of a frame constructed in accordance with embodiments of the invention;  
         [0014]      FIG. 4  is an end view of the frame of  FIG. 3 ; and  
         [0015]      FIG. 5  is a sectional end view of a cross head disposed in a frame constructed in accordance with embodiments of the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]     Referring now to  FIGS. 1 and 2 , reciprocating compressor  10  comprises frame  14 , crankshaft  16 , connecting rods  18 , cross heads  20 , pistons  22 , cylinders  24 , and valve assemblies  26 . A power supply is coupled to one end of crankshaft  16  and provides the power to rotate the crankshaft. Crankshaft  16  is supported within frame  14 . Connecting rods  18  couple cross heads  20  and pistons  22  to crankshaft  16 . Pistons  22  move linearly within cylinders  24 . Valve assemblies  26  control flow into and out of cylinders  24 .  
         [0017]     As crankshaft  16  is rotated by a power supply, connecting rods  18  and cross heads  20  transform the rotational motion of the crankshaft into linear movement of pistons  22  within cylinders  22 . As pistons  22  stroke forward within cylinders  24 , the pressure within the cylinder increases until discharge valves in valve assembly  26  open to allow pressurized fluids to exit the cylinder. As pistons  22  stroke backward, the pressure within the cylinders  24  decreases and an inlet valve in valve assembly  26  opens to allow fluid to fill the cylinder. Crankshaft  16  is arranged such that while one piston strokes forward the piston on the opposite side of the crankshaft strokes backward. While this arrangement helps maintain balance, the coupled moments, which are formed by the variation of plane of action of the pistons&#39; operation, are transferred by the crank shaft  16  and are supported by the frame of compressor  10 .  
         [0018]     Regardless of the efforts taken to balance crankshaft  16 , there will be some unbalanced forces and compressor  10  will be subject to vibratory reciprocating loads. By supporting crankshaft  16  and all of the other moving components, frame  14  will be subjected to the reciprocating loads, coupled moments, and torque on the crankshaft and has to be able to withstand those loads without excessive distortion. In order to improve the distribution of the reciprocating loads, coupled moments, and torque as well as the distortion of the frame itself, frame  14  is a “barrel”-type frame comprising a continuous, curved wall  28  that forms a crankshaft housing  30 .  
         [0019]     Curved wall  28  surrounds crankshaft  16  such that the loads generated in a plurality of directions by the movement of the crankshaft and the reciprocating actions of the piston assemblies are transferred to the wall. Because wall  28  is continuously curved, every element of the wall is supported by adjacent elements within the wall and the curved wall is effectively self-supported against these loads in a plurality of directions. Therefore, no external tie bars are necessary to support and balance the reciprocating loads as are found in the existing art. Curved wall  28  also improves the efficiency with which the reciprocating loads, coupled moments, and torque are dissipated, thus allowing a reduction in wall thickness, and hence a reduction in the weight of frame  14  versus a conventional box-type frame.  
         [0020]     Referring now to  FIGS. 3 and 4 , barrel-type frame  14  integrally comprises curved wall  28 , housing  30 , cross head shoe supports  32 , base flange  34 , end flanges  36 , bearing supports  38 , lubricant sump  40 , and access openings  42 . Frame  14  is shown as having two cross heads, but multiple pairs of cross heads are possible. Frame  14  may be constructed from a single casting that is machined to include desired features. Constructing frame  14  from a single piece of material eliminates welding and other high-temperature processes that may distort the frame. Furthermore Frame  14  may be constructed with plurality of ribs formed between wall  28 , base flange  34 , and cross head shoe supports  32  that provide structural rigidity and potentially increase thermal transfer capability of the frame.  
         [0021]     Base flange  34  is a flat, rectangular member that provides a base suitable for attachment to a foundation or other structure that will support the compressor. Base flange  34  may comprise a bolt pattern or other means for securing the compressor. Curved wall  28  extends from base flange  34  to form substantially cylindrical housing  30  having end flanges  36 . Although curved wall  28  is illustrated as being substantially cylindrical, other curved shapes are possible and may provide advantages in certain applications.  
         [0022]     Housing  30  provides an enclosure adapted to receive a crankshaft and comprises bearing supports  38 , lubricant sump  40 , and access openings  42 . Bearing supports  38  provide mounting and attachment points for bearings that support the crankshaft. Lubricant sump  40  provides a reservoir of lubricant that can be used to lubricate the bearings and crankshaft. Access openings  42  provide access to the crankshaft and other components installed within the housing. When in operation, access opening  42 , as well as end flanges  36  may be covered with simple hinged covers, clamped covers, or other type covers.  
         [0023]     Frame  14  also features cross head shoe supports  32  that are constructed integral with wall  28 . Integral cross head shoe support  32  provides support for each of the shoes and cross head as well as further increase the strength of wall  28 . The integral feature of cross head shoe support  32  with the frame  14  also allows machining of the crank shaft bore and the cross head shoe support bore with the same machining set up. This eliminates misalignment problems between the cross head with the crank shaft as it is inherent with the conventional separate cross head guide design. Furthermore, the integral design eliminates the extra machining and bolting arrangement which is required by the conventional attachment design.  
         [0024]     Cross head shoe supports  32  comprise an internal cavity  44  shaped to receive cross head and cross head shoe. Cavity  44  may be fitted with a stationary cross head shoe  50 , see  FIG. 5 , that provides a precision-machined surface for guiding the cross head  52 . Shoes  50  are removable and can be replaced as needed. By mounting cross head shoes  50  on shoe support  32 , the surfaces of the shoe support are protected from damage and only the shoes need to be replaced in the event of surface wear. Hence, the replaceable shoes will protect frame  14  from any primary damage caused by the motion of cross head on the shoes. In certain embodiments, cross head shoe supports  32  have access openings that allow for the removal and replacement of shoes  50  without removing cross head  52 .  
         [0025]     While preferred embodiments of this invention have been shown and described, modifications thereof can be made by one skilled in the art without departing from the scope or teaching of this invention. The embodiments described herein are exemplary only and are not limiting. Many variations and modifications of the system and apparatus are possible and are within the scope of the invention. For example, the relative dimensions of various parts, the materials from which the various parts are made, and other parameters can be varied, so long as the compressor frame apparatus retain the advantages discussed herein. Accordingly, the scope of protection is not limited to the embodiments described herein, but is only limited by the claims that follow, the scope of which shall include all equivalents of the subject matter of the claims.