Abstract:
A system for accommodating thermal expansion of a pump housing. The system includes a pump having an external housing, and a mounting structure for mounting the pump. Contacting members are disposed intermediate the mounting structure and the pump for allowing one-dimensional movement of the external housing along a longitudinal axis of the external housing. Alternatively, bearing members are positioned to support the pump in the mounting structure, while allowing a thermal distortion of the housing.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to mounting assemblies, and particularly to mounting assemblies for fluid delivery devices subject to thermal variations. 
     BACKGROUND OF THE INVENTION 
     In a variety of applications, it is advantageous to utilize a horizontal pumping system (“HPS”), which generally includes a motor and a pump mounted on a horizontal skid. For example, an HPS may be used in applications such as water floods, liquid propane injection, water supply, booster service, salt water disposal and crude oil transfer. 
     In many applications, the HPS may be subject to thermal variations, distortions, vibrations and stresses leading to pump failure. For example, displacing high temperature fluids through an HPS typically leads to thermal growth of the pump. Existing HPSs fixedly mount the pump to the horizontal skid, thereby preventing movement of the pump as the pump grows and contracts due to thermal variations. The fixed mounting technique combined with these thermal variations results in mechanical stresses, fatigue and eventually mechanical failure and downtime of the HPS. 
     Accordingly, it would be advantageous to provide a pump mounting assembly to permit thermal distortions (expansion and contraction) of the HPS components, thereby reducing stresses and mechanical failure of the HPS. For example, allowing axial expansion of the pump may significantly reduce fatigue and stresses and improve the lifetime performance of the HPS. 
     SUMMARY OF THE INVENTION 
     The present invention features a system for accommodating thermal expansion of a pump housing. The system includes a pump having an external housing, and a mounting structure for mounting the pump. Additionally, a plurality of contacting members are advantageously disposed intermediate the mounting structure and the pump. The contacting members are configured for allowing one-dimensional movement of the external housing along a longitudinal axis of the external housing. 
     Another aspect of the invention features a fluid delivery system including a pump having a housing, and a mounting structure for mounting the pump. Additionally, a plurality of bearing members are advantageously positioned to support the pump in the mounting structure, while allowing a thermal distortion of the housing. 
     Another aspect of the invention features a method for reducing wear of a fluid delivery device. The method includes the act of affixing the fluid delivery device to a support structure at a first predetermined axial position. Additionally, the method advantageously includes the act of providing a support at a second axial position that permits axial movement of the fluid delivery device to alleviate distortions from thermal variations. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and: 
     FIG. 1 is a perspective view of a horizontal pumping system having a mount assembly; 
     FIG. 2 is a cross-sectional view of the horizontal pumping system illustrating contacting members for the mount assembly; 
     FIG. 3 is a cross-sectional view of the clamping assembly illustrating an alternate configuration of contacting members; and 
     FIG. 4 is a cross-sectional view of the horizontal pumping system illustrating bearing members for the mount assembly. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring generally to FIG. 1, an exemplary horizontal pumping system (“HPS”)  10  is illustrated according to a preferred embodiment of the present invention. The HPS  10  includes a pump  12 , a motor  14  drivingly coupled to the pump  12 , and a horizontal skid  16  for supporting the pump  12  and the motor  14 . Preferably, the pump  12  is a centrifugal pump or a positive displacement pump, while the motor  14  is an electric motor. However, the HPS may utilize other pumps  12  and motors  14  for a given application. 
     The motor  14  is fixedly coupled to the horizontal skid  16  at a motor mount surface  18  of the horizontal skid  16 . The pump  12  is coupled to the horizontal skid  16  by a mount assembly  20 . The mount assembly  20  includes a support  22  (e.g., a fixed support) and clamp assemblies  24  and  26 . Support  22  extends outwardly from the motor mount surface  18  at an axial position  28  lengthwise along the horizontal skid  16 . The pump  12  is drivingly coupled to the motor  14  through the support  22 . 
     Alternatively, the support  22  may be an external conduit assembly configured for attachment to a pump conduit, such as one of two pump conduits  29  extending from the pump  12 . The support  22 , in either the illustrated configuration or as an external conduit assembly, may axially fix the pump  12  or may allow axial movement of the pump  12  with respect to the support  22 . These pump conduits  29  are configured to receive and expel a fluid, or vice versa, as the pump  12  operates. For example, the pump  12  may displace water, salt water, sewage, chemicals, oil, liquid propane, or other fluids in through one of the pump conduits  29  and out of the other pump conduit  29 . In addition, the temperature of the fluids may vary. For example, some applications may involve pumping hot fluids, while others may involve pumping cold fluids. In addition, the temperature may change during the pumping operation, either from the source of the fluid itself, or possibly due to the heat generated by the operation of the pump  12  and/or the motor  14 . In addition, temperature may change dramatically due to weather change. 
     Preferably, the pump  12  has a fixed end  30  and a free end  32 , the fixed end  30  being axially fixed at the support  22 . The clamp assemblies  24  and  26  are coupled to the horizontal skid at axial positions  34  and  36 , respectively, and preferably generally parallel with the support  22 . The clamp assemblies  24  and  26  have base members  38  and  40  and upper clamps  42  and  44 , creating clamping conduits  46  and  48 , respectively, for mounting the pump  12  in the clamping conduits  46  and  48 . 
     In a preferred embodiment, the clamp assemblies  24  and  26  are configured to allow axial movement of the pump  12  through the clamping conduits  46  and  48 . This axial freedom is intended to reduce stresses and fatigue, and possible mechanical failure, due to vibrations and thermal expansion/contraction of the pump  12 . Furthermore, the number and geometry of clamp assemblies may vary depending on the application, size of the pump  12 , and other factors. 
     FIG. 2 is a cross-sectional view of the HPS  10  illustrating an embodiment of the mount assembly  20  having contacting members  50 ,  52  and  54  disposed on an inner surface  56  of the clamp assemblies  24  and  26 . The contacting members  50 ,  52  and  54  advantageously reduce the contact area, and consequently the frictional force, between the clamp assemblies  24  and  26  and the pump  12 , thereby allowing the pump  12  to move axially within the clamping conduits  46  and  48 . Although FIG. 2 illustrates three contacting members, the number and geometry of the contacting members may be changed depending on the application and design parameters. In each such design, the contacting members are used to reduce friction and promote axial freedom of the pump  12  within the clamping conduits  46  and  48 . 
     FIG. 3 is a cross-sectional view of the clamp assemblies  24  and  26  illustrating an alternate configuration of contacting members. The exemplary embodiment illustrated in FIG. 3 has three sets  58 ,  60  and  62  of contacting members, each set comprising four contacting members  64 ,  66 ,  68  and  70 . The three sets  58 ,  60  and  62  are axially spaced along the clamping conduits  46  and  48  at axial positions  72 ,  74  and  76 . Although the contacting members  64 ,  66 ,  68  and  70  illustrated in FIG. 3 are angularly spaced about the clamping conduits  46  and  48  at equal angles ,the contacting members may be spaced at other angles to better support movement of the pump  12  through the clamping conduits  46  and  48 . Also, the clamp assemblies  24  and  26  may have other numbers of sets, and the sets  58 ,  60  and  62  may have other numbers of contacting members depending on the application. 
     FIG. 4 is a cross-sectional view of the HPS  10  illustrating an alternate embodiment of the mount assembly  20  having bearing members  78 ,  80  and  82  disposed on the inner surface  56 . The bearing members  78 ,  80  and  82  are preferably ball bearings or roller pin bearings, which further improve the axial freedom of the pump  12  within the clamping conduits  46  and  48 . Alternatively, the bearing members  78 ,  80  and  82  may embody needle bearings, or rotatable members disposed in a holder or cage. The bearing members  78 ,  80  and  82  advantageously create rotatable contacts between the clamp assemblies  24  and  26  and the pump  12 , thereby significantly reducing any resistance to axial movement of the pump  12  while maintaining lateral and vertical support of the pump  12 . Although FIG. 4 illustrates three bearing members, the number and geometry of movable or rotatable bearing members may be changed, while still reducing friction and promoting axial freedom of the pump  12  within the clamping conduits  46  and  48 . For example, there may be more than one set of bearing members  78 ,  80  and  82  in each of the clamping conduits  46  and  48 . Also, there may be multiple bearing members disposed at locations around the inner surface  56 , or there may be multiple sets of bearing members disposed at multiple axial locations along the inner surface. For example, the bearing members  78 ,  80  and  82 , as illustrated in FIG. 4, may have an adjacent set of bearing members disposed axially behind or in front of the bearing members  78 ,  80  and  82  shown in FIG.  4 . 
     Alternatively, the present invention involves a technique for reducing stress, fatigue and/or wear of a fluid delivery assembly such as the HPS  10 . The technique includes the act of fixing a component of the fluid delivery assembly to a support assembly at a first axial position. For example, the technique may involve fixing the pump  12  to the support  22 , as discussed above. The technique further includes providing a support member for the component at a second axial position. Such a support member is configured to allow axial movement of the component. This axial movement may be desirable to alleviate stresses, fatigue and/or wear caused by vibrations, movement and/or expansion/contraction of the component, or other mechanical factors. For example, the pump  12  may expand/contract due to thermal variations in the HPS  10 . Allowing axial movement of the component significantly reduces the chance for mechanical failure, and increases the life of the fluid delivery assembly. 
     The technique may further include introducing bearing members to enhance the axial movement of the component. The bearings may be disposed about the component in a configuration suitable for reducing resistance to axial movement. For example, three bearing members may be disposed about the pump  12 , as previously discussed. 
     The technique may further include disposing the bearings, or bearing members, between the component and the support assembly. For example, bearing members may be disposed between the pump  12  and the clamp assemblies  24  and  26 , as discussed above. 
     The technique also may also involve maintaining a mechanical clearance within the fluid delivery assembly by allowing the axial movement. For example, if an elongated component with internal parts is fixed at two axial positions, and the elongated component is subject to thermal variations causing actual expansion or contraction, the elongated component may bow or otherwise deform. This deformation could result in reduced internal clearances between moving parts, which could then cause increased wear and possible mechanical failure. Accordingly, providing the axial movement can be important for maintaining clearances and preventing undesirable wear and failure. 
     It will be understood that the foregoing description is of preferred exemplary embodiments of this invention, and that the invention is not limited to the specific forms shown. These and other modifications may be made in the design and arrangement of the elements without departing from the scope of the invention as expressed in the appended claims.