Abstract:
This invention relates generally to a piston assembly and more specifically to a piston assembly in a prepackaged configuration. The prepackaged piston assembly is ready for immediate installation into an engine or compressor. The piston assembly has a plurality of rings preinstalled on a piston member and a sleeve position about the piston member and the plurality of rings maintaining the rings in a compressed position ready for installation into an engine. The piston assembly is lowered into a cylinder bore, the sleeve contacts the top surface of a block and the piston assembly can be easily installed into the cylinder bore without the need for the mechanic to compress the plurality of rings. Thus the present invention reduces time and expense required for rebuilding and engine and increases the quality of the rebuild.

Description:
[0001]    This is a continuation-in-part of co-pending application Serial No. 09,452,071, filed on Nov. 10, 1999.  
         TECHNICAL FIELD  
         [0002]    This invention relates generally to an internal combustion engine and more specifically to prepackaged piston assemblies which are provided with a plurality of piston rings positioned on each piston member and held in a compressed position.  
         BACKGROUND  
         [0003]    Internal combustion engines have numerous components which need to be assembled in order to provide a complete engine. Engine repair facilities, new engine manufacturers and engine re-manufactures are constantly looking for ways to improve quality and reduce cost of assembling engines. Many engine components are supplied by manufactures other than the engine assembly facility. Engine components such as, pistons, rings, connecting rods and wrist pins are often packaged, shipped and stored separately at the engine manufacturer or assembler. Supplying engine components in this manner is costly, and increases the opportunity to damage components.  
           [0004]    Additionally, when used engine components have undergone an excessive amount of wear, the performance and efficiency of the engine is reduced. Engines which have undergone excessive wear are often rebuilt by replacing major components. Many of the components that are normally replaced during the rebuilding process include pistons, piston rings, connecting rods, rod bearings, and main bearings. This rebuilding of the engine brings the engine back to or near, the engine manufacturer&#39;s original performance or specifications. To insure the quality of the rebuilt engine the rebuild process is preferably done in a controlled environment such as a factory or repair shop.  
           [0005]    Often with large machines utilizing internal combustion engines, such as those used in the construction and mining industry, the size of the machine restricts transportation to an engine rebuild shop, or the time permitted for the rebuild process requires that the engine of the machine be rebuilt in the field. Often when engines are rebuilt the quality of the rebuild may be jeopardized due to incorrect inspection or assembly of major components such as pistons and piston rings. Loss of quality may increase with engines which are rebuilt in the field under less than an ideal controlled environment.  
           [0006]    Additionally the amount of time required to prepare components such as piston assemblies for the rebuild process may be significantly greater in a repair shop or the field than if the same work is done in a factory where larger quantities of components are assembled and manufacturing processes and procedures can be systematically followed. Often in the factory, repetitive work is performed at lower labor cost than where the same work is performed by a skilled mechanic in the field.  
           [0007]    The present invention overcomes many of the above identified problems by providing piston assemblies which have been inspected and assembled in a factory environment and packaged in a manner which reduces the likelihood of quality related problems. Labor cost to assemble an engine may also be reduced by eliminating the number of steps to assemble the engines.  
         SUMMARY OF THE INVENTION  
         [0008]    In one aspect of the invention a piston assembly has a prepackaged configuration and is adapted for use with an engine. The engine is comprised of a piston member with a plurality of ring grooves. A plurality of rings are positioned in the ring grooves. A sleeve is positioned about the piston member and the plurality of rings, maintaining the plurality of rings in a compressed position. A container is positioned about the piston member, plurality of rings, and the sleeve.  
           [0009]    In another aspect of the invention a method of assembling a piston assembly in an engine is disclosed. The piston assembly has a prepackaged configuration and comprises a piston member with a plurality of rings thereon and a sleeve positioned around the piston assembly and the plurality of rings. The sleeve maintains the plurality of rings in a compressed position. The method of assembly comprises the following steps. Removing the piston assembly from a container. Positioning the piston assembly in alignment with a cylinder bore. Removing the piston assembly from the sleeve. And, simultaneously inserting the piston assembly into the cylinder bore. The sleeve is discarded after the piston assembly has been installed into the engine.  
           [0010]    In another aspect of the invention a sleeve adapted for use with a piston assembly of an engine is provided. The sleeve includes a top surface, a bottom surface and an outer wall. A window is provided in the outer wall.  
           [0011]    In another aspect of the invention a method is provided for manufacturing a sleeve for use with a piston assembly having a pre-packaged configuration is provided. The method includes the steps of providing a tube having a predetermined inside diameter, removing a length of the tube and providing a window in the removed tube. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is a partially sectioned view of an engine having a prepackaged piston assembly partially installed therein;  
         [0013]    [0013]FIG. 2 is a exploded view of a piston assembly and components of the prepackaged configuration;  
         [0014]    [0014]FIG. 3 is a perspective view of a plurality of piston assemblies without connecting rods arranged in a shipping container.  
         [0015]    [0015]FIG. 4 is a top view of a of a plurality of pre-packaged piston assemblies arranged on a shipping container.  
         [0016]    [0016]FIG. 5 is a perspective view of a sleeve, or ring compressor, for maintaining the rings of the prepackaged piston assembly in the compressed position; and  
         [0017]    [0017]FIG. 6 is a perspective view of a second embodiment of the sleeve for maintaining the rings of a prepackaged piston assembly in the compressed position.  
         [0018]    [0018]FIG. 7 is a perspective view of a strap for use as an alternate embodiment of a sleeve.  
         [0019]    [0019]FIG. 8 is a partially sectioned view of an embodiment of an alternate sleeve and latching member.  
         [0020]    [0020]FIG. 9 is a partially sectioned view of an embodiment of an alternate sleeve and latching member.  
         [0021]    [0021]FIG. 10 is a partially sectioned view of an embodiment of an alternate sleeve and latching member.  
         [0022]    [0022]FIG. 11 is a partially sectioned view of an embodiment of an alternate sleeve and latching member. 
     
    
     DETAILED DESCRIPTION  
       [0023]    Although this embodiment of the present invention refers to use of a piston assembly  10  in a prepackaged configuration  12  for use with an internal combustion engine  14 , it should be recognized that the invention is equally as valuable in use with an air compressor or other machines using piston assemblies.  
         [0024]    Referring first to FIG. 1, the engine  14  is illustrated as a partially sectioned view of an engine block  16 . A portion of a prepackaged piston assembly  18  is also shown. The block  16  defines a top surface  20  and a pair of outer walls  24  extending downward from each end of the top surface  20 . A cylinder bore  26  extends downward from the top surface  20 . The cylinder bore  26  may be positioned in a replaceable liner or a fixed bore in the engine block  16 . In this application, a water jacket  28  is interposed the cylinder bore  26  and the outer walls  24 ; however, as an alternative the engine  14  could be air cooled.  
         [0025]    The prepackaged piston assembly  18  as best shown in FIG. 2 is comprised of a piston assembly  10  a sleeve  30  and a container  32 . The piston assembly  10  has a piston member  36  having a top portion  38  and an outer surface  40  defined on the piston member  36 . A plurality of ring grooves  42  are positioned in the outer surface  40  below the top portion  38  and a plurality of rings  46  are inserted in the ring grooves  42 . The plurality of rings  46  define a ring spread  48 . The ring spread  48  can be defined as an axial distance between the top of a top ring groove  50  and the bottom of a bottom ring groove  52 . A wrist pin bore  54  extends through the outer surface  40  of the cylindrical piston member  36 . A snap ring groove  58  is defined within the wrist pin bore  54  near each end. As an alternative the piston assembly  10  may further have a connecting rod  60 . The connecting rod  60  is affixed to the piston member  36  in a conventional manner by using a wrist pin  62 . A lubricant and or rust inhibitor may be applied to all or some surfaces of the pre-packaged piston assembly  18 .  
         [0026]    In the prepackaged configuration  12  of the piston assembly  10 , the sleeve  30  is positioned about the piston member  38  and the plurality of rings  46 . The sleeve  30  maintains the plurality of rings  46  in a compressed position. The pre-packaged piston assembly  18  may in be an individual configuration, or may be in a multiple configuration as shown if FIGS. 3 and 4. The pre-packaged piston assembly  18  may include the connecting rod  60  although it is not required.  
         [0027]    The sleeve  30  may be manufactured in a number of ways. Preferably the sleeve  20  is manufacture from a material and in a manner that would minimize cost. As further shown in FIG. 5, a perspective view of one sleeve  30  of the present invention is illustrated. The sleeve  30  has a top surface  64  a bottom surface  66  and an outer wall  68 . A sleeve bore  70  (or inner wall) extends between the top surface  64  and the bottom surface  66 . A window  74  may extend from the outer wall  68  to the sleeve bore  70 . An alternative to the window  74  is a sleeve being made from a transparent material. The sleeve bore  70  is of a predetermined inside diameter  76  which is equal to or slightly smaller than the diameter of the cylinder bore  26  and slightly larger the outside diameter  78  of the piston member  36 .  
         [0028]    As further shown in FIG. 6, another embodiment of the sleeve  30  is shown. The sleeve  30  has a top surface  64  a bottom surface  66  and an outer wall  68 . A sleeve bore  70  is defined between the top surface  64  and the bottom surface  66 . The sleeve bore  70  defines a straight portion  80  extending from the bottom surface  68  toward the top surface  66 . A tapered portion  82  of the sleeve bore  70  extends outwardly from a top end  84  of the straight portion  80  to the top surface  64 . The length of the straight portion  80  is at least equal to the ring spread  48  of the piston member  36 .  
         [0029]    Referring now to FIGS. 7-11, an alternate sleeve  30 ′ may be formed from a substantially flat strap  86 . The formed sleeve  30 ′ provides a variable inside diameter  90  that is substantially equal to that of the piston member  36 . The flat strap  86  includes a sleeve portion  88  having predetermined width  92  at a first end  94  of the strap  86 . Additionally, the sleeve portion  88  includes a predetermined length  95 . The predetermined length  95  must be at least equal to the circumference of the piston member  36  that the sleeve  30  will be used on. A second end  96  has a narrower width than that of the predetermined width  92 . The predetermined width  92  is equal to or greater than the ring spread  48  of the piston member  36 . A latching member  100  is provided near the first end  94 . The latching member  100  is adapted to receive the second end  96 , to form the sleeve  30 ′. The latching member  100  is preferably adapted to varying the inside diameter  76  of the sleeve  30 ′.  
         [0030]    The latching member  100  may be provided in a variety of configurations. Some examples of latching members  100  are described hereafter, but it should be noted that any number of conventional latching members are suitable, yet not described.  
         [0031]    An embodiment of a latching member  100  is illustrated in FIG. 8, and is similar to that of a plastic wire tie. The latching member  100  includes a body portion  102 . The body portion  102  has a slot  104  defined therein. At least one barb  108  (or catch) is disposed within the slot  104 . A mating portion  110  of the strap  86  is adapted to be positioned within the slot  104 . The mating portion  110  may include a friction portion  112 . The friction portion  112  illustrated in FIG. 7 is a plurality of ribs  114  disposed along a surface  116  of the strap  86 . The friction portion  110  is configured to permit movement of the mating portion  110  relative to the slot  104 .  
         [0032]    Referring now to FIG. 9, an embodiment for the latching member  100  is similar to that used to adjust the size of a hat. Near the first end  94  of the strap  86  a plurality of openings  120  are spaced predetermined distance from one and other. On the first end  94  of the strap  86  one or more protrusions  122  extend outward from the surface  116  of the strap  86 . The protrusions  122  include a body portion  124  and a head portion  126 . The body portion  124  of the protrusion  122  is of a slightly smaller diameter than that of the head portion  126 . At least one of the protrusions  122  and at least one of the openings  120  are adapted to engage one and other and form a sleeve  30  of the appropriate inside diameter  76 .  
         [0033]    Referring now to FIG. 10, an embodiment of a latching member  100  is illustrated. The body portion  102  is defined near the first end  94  of the strap  86 . The body portion  102  also includes the slot  104  and is adapted to receive the second end  96 . Within the body portion  102  a rotatable cam  130  is disposed, and pivotable between a first and second position. The cam  130  includes a lever portion  132  adapted to rotate the cam  130 . In the first position the second end  96  of the strap  86  is moveable within the slot  104 . With the cam  130  in the second position, the second end  96  is fixedly interposed the cam  130  and the slot  104 .  
         [0034]    Referring now to FIG. 11, an embodiment of the latching member  100  having a wedge member  134  is illustrated. The wedge member  134  is positioned within the slot  104  and moveable between a first position and a second position. In the first position the second end  96  of the strap  86  is moveable within the slot  104 . With the wedge member  134  in the second position the second end  96  of the strap  86  is fixedly interposed the slot  104  and the wedge member  134 .  
         [0035]    Referring again to FIG. 2, in the prepackaged configuration  12 , the pre-packaged piston assembly  18  is sealed in the container  32 . In this embodiment the container is a plastic bag  138 . The plastic bag  138  is coated on the inside with a rust inhibitor and/or lubricant. The plastic bag  138  defines a cavity  140  which is capable of accommodating the prepackaged configuration  12  of the piston assembly  10 . Alternatively of the plastic bag  138 , a flexible sheet having a protective coating and a seal  142  could be used. The flexible sheet may be constructed of many different materials including, but not limited to, paper, waxed paper and plastic. The flexible sheet may additionally be coated or impregnated with the rust inhibitor and/or lubricant.  
         [0036]    Referring again to FIGS. 3 and 4, a plurality of pre-packaged piston assemblies  18  arranged in a single shipping container is shown. The piston assemblies  10  may include the connecting rod  60  as illustrated in FIG. 4. As shown in FIG. 3, the piston assemblies  10  may be packaged without the connecting rod  60 . The piston assemblies  10  may be coated with the lubricant and/or rust inhibitor as previously discussed. A foam sheet having a plurality of cavities  158  that are shaped to fit the piston assemblies  10  may be used. Alternately, conventional packing materials may surround all or part of the piston assemblies  10 . The second container  144  may further be adapted to receive a plurality of layers of piston assemblies  10 . Each of the plurality of layers may be positioned on a tray  162  that is adapted to hold the packing materials and piston assemblies  10 . Sheets of plastic or paper having a protective coating may be wrapped around the piston assemblies  10 . The sheets of plastic or paper may also be coated with the lubricant and/or rust inhibitor. The second container  144  and/or the sheets may further be hermetically sealed.  
         [0037]    Referring again to FIG. 2, a second container  144  may also be provided but is not required in the present invention. The second container  144  illustrated in FIG. 2 has a cylindrical configuration, but as an alternative could have other shapes such as a square or octagonal configuration. The second container  144  has a container wall  150  and a bottom  152 . An opening  154  in a top end of the second container  144  is closable. For example, a cap (or a top)  156  can be positioned in/or over the opening  154 . Or as an alternative the second container  144  could be a box having an attachable top  156 . The second container also  144  defines a container cavity  158  which is of a sufficient size to allow insertion of the prepackaged configuration  12  of the piston assembly  18  or a plurality thereof. The second container  144  is adapted to hold the components firmly therein. A container seal  160  may be provided on the top  156  of the second container  144  to engage the container wall  150  when the top  156  is positioned over the opening  154 . Additionally, alternate containers could be manufactured from foam, plastic or fiber materials.  
         [0038]    While the invention is susceptible to various modifications and alternative forms, a specific embodiment thereof has been shown by way of example in the drawings and is herein described in detail. It should be understood, however, that there is no intent to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.  
       INDUSTRIAL APPLICABILITY  
       [0039]    The prepackaged piston assembly  10  of the present invention is prepared in the following manner. Components including the piston member  36  the plurality of rings  46  and the sleeve  30  are gathered and inspected for conformity to manufacturer&#39;s specifications. The plurality of rings  46  are installed into the ring grooves  42  in the appropriate positions. The plurality of rings  46  are compressed using a conventional ring compressor. Referring to the sleeve  30  of FIGS. 5 and 6, the sleeve  30  is positioned around the piston member until the sleeve  30  contacts the ring compressor. The sleeve  30  is pushed or pulled against the ring compressor sliding the sleeve  30  over the plurality of rings  46 . As the sleeve  30  slides over the plurality of rings  46  the ring compressor slides off of the plurality of rings  46 . When the plurality of rings are confined completely within the sleeve bore  54  the ring compressor is removed from the piston member  68 .  
         [0040]    If the sleeve  30  of the embodiment of FIG. 6 is to be used, the step of compressing the plurality of rings  46  would not require a conventional ring compressor. After the plurality of rings  46  are properly positioned on lower portion of the piston member  36  the sleeve  30  is positioned over the piston member  36  with the tapered portion  82  toward the plurality of rings  46 . The sleeve  30  is them moved toward the plurality of rings  46  wherein the tapered portion  82  compresses the plurality of rings  46  as it moves. Movement of the sleeve  30  is ceased when the plurality of rings  46  are confined within the straight portion  80  of the sleeve  30 .  
         [0041]    Referring to the alternate sleeve  30 ′ of FIGS. 7-10 the standard ring compressor is not require and the following procedure is used. After the components have been inspected, the plurality of rings  46  are installed into the ring grooves  42 . The strap  86  is wrapped around the plurality of rings  46  that were previously installed in the ring grooves  42 . The second end  96  of the strap  86  is mated with the latching member  100  and pulled until the plurality of rings  46  are in the compressed position. Once the plurality of rings  46  are in the compressed position, the latching member  100  is used to fix the variable inside diameter  90  of the sleeve  30 ′ and maintain the plurality of rings  46 .  
         [0042]    A connecting rod  60  can be included with the piston assembly  10  or attached by the mechanic, since the sleeve  30  does not interfere with access to the wrist pin bore  54 . The piston assembly  10  is next inserted into the a container  32  impregnated with a rust inhibitor and/or lubricant. Alternately, piston assembly may be coated with lubricant and/or rust inhibitor and vacuum sealed. The container  32  and rust inhibitor/lubricant protects the piston assembly  10  from environmental contaminants such as dirt and moisture during storage and transportation of the prepackaged piston assembly  18 . The pre-packaged piston assembly  12  can be positioned in a second container  144  to protect the piston assembly  10  from physical damage such as breaking or scratching. The second container  144  may be adapted to hold a plurality of piston assemblies  10  in a pre-packaged configuration  12 . However it is possible to have a single container which is capable of protecting the all piston assemblies  10  from all of the previously mentioned concerns. The container(s)  32 , 144  can additionally be sealed in a manner which requires breaking of the seal  140  when the prepackaged piston assembly  18  is removed by the mechanic. Usage of the seal  140  verifies to the mechanic that the piston assembly  10  has not been tampered with and conforms to the manufacturers&#39; specifications.  
         [0043]    After the engine block  16  has been prepared for assembly, installation of the pre-packaged piston assemblies  18  is accomplished by breaking the seal  140  and opening the container  32 . The pre-packaged piston assembly  18  is then removed from the container  32 . Although not required for the proper use of this invention, but desirable of a diligent mechanic, the position of the plurality of rings  36  may be verified through the transparent sleeve  30  or window  74 . In this example a connecting rod  60  is attached to the piston assembly  10 . The pre-packaged piston assembly  18  is now positioned above the respective cylinder bore  26  waiting installation. The piston assembly  10  is next lowered toward the cylinder bore  26  with the connecting rod  60  inserted first. The piston assembly  10  is further lowered toward and into the cylinder bore  26  until the bottom surface  66  of the sleeve  30  contacts the top surface  20  of the engine block  16 . When the sleeve  30  contacts the block  16  the piston assembly  10  can be further inserted into the cylinder bore  26  by pushing on the top portion  38  of the piston member  36  or by pulling on the connecting rod  60 . After the plurality of rings  46  have entered the cylinder bore  26  the sleeve  30  can be discarded. When all piston assemblies  10  have been installed into the engine  14  the remainder of the engine  14  components are assembled in a typical fashion.  
         [0044]    The sleeve  30  of the present invention can be manufactured in a number of ways. Metal sleeves  30  can be machined from a removable cylinder liner by cutting the sleeves  30  to length and deburring the cut edges. Additionally sleeves  30  could be cut from a piece of tube or pipe with the proper inside diameter. A third method of manufacturing sleeves  30  could include injection molding from a plastic or alternate material.  
         [0045]    Primary considerations of manufacturing sleeves  30  is to select a material which is sufficiently rigid to resist distortion and thermal expansion. Since there is typically only 0.002″ difference between the inside diameter of the cylinder bore  26  and the outside diameter  78  of the piston member  36  the material characteristics must allow manufacturing to close tolerances. The cost of the selected material for the sleeve  30  should also be inexpensive, thus allowing the sleeve  30  to be discarded after a single use. Recycling sleeves  30  at this time does not appear to be a cost effective option since it would require the added expense of transportation.  
         [0046]    Thus is can be seen that using a piston assembly  10  in the prepackaged configuration  12  during the assembly of an engine  6  increases quality of the rebuilt engine  14  by insuring that the piston assembly meets or exceeds manufacturers&#39; specifications. Quality of the engine  14  is also enhanced when because the piston assembly  10  is less likely to be contaminated by dirt or moisture. The cost of rebuilding an engine  14  using the prepackaged piston assembly  18  is reduced because the time required to assembly large quantities of piston assemblies  10  in a factory setting is typically less than assembling small quantities in the field.