Abstract:
A process ( 30 ) is presented for the post-honing cleaning and lubrication of a cylinder ( 24 ) of a reciprocating engine ( 22 ) prior to assembly thereof. The process ( 30 ) includes cleaning ( 32 ) the cylinder ( 24 ) with a water-and-wetting-agent solution and with a solvent in an effort to remove contaminants. The process ( 30 ) also includes lubricating ( 40 ) the cylinder ( 24 ) with a penetrating oil, and coating ( 42 ) the cylinder ( 24 ) with an indicating lubricant ( 28 ) formed of a powdered mixture of tungsten disulfide and graphite. The indicating lubricant ( 28 ) is configured to change color to assume a specific tint when contaminants have been substantially removed from the cylinder ( 24 ), and to refrain from assuming that tint when contaminants have not been substantially removed from the cylinder ( 24 ). The process ( 30 ) includes repeating the cleaning ( 32 ), lubricating ( 40 ), and coating ( 42 ) activities when the indicating lubricant ( 28 ) has refrained from assuming that tint, and allowing ( 48 ) assembly of the engine ( 22 ) to proceed when the indicating lubricant ( 28 ) has assumed that tint.

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to methods of post-honing reciprocating-engine cylinder preparation. More specifically, the present invention relates to the use of cylinder lubricants incorporating cleanliness indicators in connection with post-honing engine assembly methods. 
     BACKGROUND OF THE INVENTION 
     In the manufacture or remanufacture of reciprocating engines, it is typically necessary to bore and/or hone the engine cylinders. The processes of boring and/or honing a cylinder leave a fine contaminant residue. This residue and other contaminants (e.g., soil, dust, and corrosion particles) must be removed prior to engine assembly. A failure to remove these contaminants will result in excessive initial engine wear, shortening the overall performance life of the engine and, in some cases, posing a risk of catastrophic failure. 
     These boring and/or honing processes are often performed in a modest service or customization facility. Such facilities typically lack the elaborate (and expensive) cleaning instrumentality of a production-engine manufacturing facility. Adequate pre-assembly cleaning is therefore typically more of a problem for the modest service or customization facility than the production facility. 
     The very processes of boring and/or honing a cylinder produce process debris. This debris is typically made up of a mixture of particulate matters removed from the inner surface of the cylinder mixed and from the boring and/or honing tool, i.e., of bits of cylinder and bits of abrasive. A portion of this debris embeds itself into the inner surface of the cylinder. This embedded debris is not easily removed from the cylinder. A cylinder may be made visually clean (i.e., the cylinder contains no contaminants visible to the naked eye) and wiping clean (i.e., a white cloth used to wipe the cylinder shows no visible contaminants) without being substantially free of contaminants. 
     To prevent excessive wear and associated problems during engine run-in, therefore, the cylinders should be adequately cleaned prior to running the engine. A cylinder is adequately cleaned when the cleaning process has removed substantially all the contaminants upon or in the inner surface of the cylinder. 
     Additionally, since a reciprocating engine must already be running before its oil distribution system can lubricate the cylinders, there is a short period of “dry” operation during run-in, i.e., when an engine is placed into operation for the first time after boring and/or honing of the cylinders. Therefore, to prevent excessive wear and associated problems during engine run-in, the cylinders should be lubricated prior to running the engine. 
     A wet initial lubrication, e.g., a coating of oil, may have a tendency to attract dirt, dust, and other contaminants during engine assembly. For this reason alone, a wet lubrication is often undesirable. 
     Typical lubricating oil (e.g., crankcase oil) is a surface lubricant. That is, it has a relatively large molecule and lubricates by clinging to the surfaces of the parts, therefore providing a barrier to part-to-part contact. In a cylinder, where piston rings wipe the surface at each stroke, such a surface lubricant must constantly be replaced. This is a task of the engine&#39;s lubrication system. 
     When such a typical lubricating oil is used to provide a wet initial lubrication, the first stroke of the piston (i.e., of the piston rings) wipes such a lubricant out of the cylinder. This leaves the cylinder dry until the oil distribution system can distribute oil to the cylinder. While short, this period of dry run-in may produce excessive wear and associated problems. 
     Since the inner surface of a cylinder will normally be inadequately lubricated during engine run-in, the cylinder will rapidly heat. This heating will expand the pores in the cylinder walls and release embedded contaminants therefrom if the cylinder was not adequately cleaned prior to assembly and run-in. These contaminants, made up mainly of honing debris (i.e., bits of cylinder material and bits of honing-tool abrasive) will contribute markedly to run-in wear and associated problems of the engine, possibly even catastrophic failure thereof. 
     To prevent excessive wear and associated problems during engine run-in, therefore, the cylinders should be both adequately cleaned and lubricated prior to running the engine. A cylinder is adequately lubricated when a penetrating lubricant is uniformly applied to the entirety of the inner surface of the cylinder. This penetrating lubricant, by being penetrating, resists being easily removed by the wiping action of the piston rings. 
     A problem does exist in determining when a cylinder has been adequately cleaned and lubricated. As discussed above, a visual inspection of cleanliness cannot determine if a cylinder has been adequately cleaned, i.e., if substantially all contaminants have been removed from the inner surface of the cylinder. It is desirable, therefore, to have some form of chemical indicator to detect the presence or absence of contaminants in the cylinder. 
     Similarly, conventional penetrating lubricants are thin lubricants, i.e., has a small molecule, in order to be penetrative. Because they are thin lubricants, typical penetrating lubricants are essentially colorless when applied. This makes it difficult if not impossible to visually ascertain if such a penetrating lubricant has been uniformly applied. It is desirable, therefore, to provide a visual indicator in the penetrating lubricant to demonstrate application uniformity. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an advantage of the present invention that an improved post-honing reciprocating-engine cylinder preparation method using a powder for piston-ring installation is provided. 
     It is another advantage of the present invention that the cylinder preparation method provided incorporates improved cleaning of the cylinder(s) to remove substantially all contaminants from the cylinder prior to engine assembly. 
     It is another advantage of the present invention that the cylinder preparation method provided incorporates an indication of cylinder cleanliness prior to engine assembly. 
     The above and other advantages of the present invention are carried out in one form by a method for the post-honing preparation of a cylinder of a reciprocating engine prior to assembly of the engine. The cylinder is cleaned in an effort to remove contaminants therefrom. An inner surface of the cylinder is coated with an indicating lubricant configured to assume a first predetermined tint when the contaminants have been substantially removed and a second predetermined tint when the contaminants have not been substantially removed. The engine is assembled when the indicating lubricant has assumed the first predetermined tint. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete understanding of the present invention may be derived by referring to the detailed description and claims when considered in connection with the Figures, wherein like reference numbers refer to similar items throughout the Figures, and: 
     FIG. 1 shows an oblique view depicting a portion of a block of a reciprocating engine demonstrating a cylinder therein in accordance with a preferred embodiment of the present invention; 
     FIG. 2 shows the oblique view of FIG. 1 depicting an inner surface of the cylinder coated with an indicating lubricant in accordance with a preferred embodiment of the present invention; and 
     FIG. 3 shows a flow chart depicting a process for preparing a cylinder for engine assembly in accordance with a preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1 and 2 show oblique views depicting a portion of a block  20  of a reciprocating engine  22  demonstrating a cylinder  24  therein, with FIG. 2 depicting an inner surface  26  of cylinder  24  coated with an indicating lubricant  28  in accordance with a preferred embodiment of the present invention. FIG. 3 shows a flow chart depicting a process  30  for preparing cylinder  24  for engine assembly in accordance with a preferred embodiment of the present invention. 
     When reciprocating engine  22  is manufactured or remanufactured, or whenever cylinder  24  of engine  22  is bored and/or honed, it is desirable that engine  22  be cleaned and lubricated prior to assembly thereof. That is, contaminants are desirably substantially removed and a penetrating lubricant is desirably applied before engine  22  is assembled and operated. This post-boring and/or post-honing preparation of cylinder  24  for assembly of engine  22  inhibits excessive wear during run-in thereof. 
     In the preferred embodiment of the present invention, the cleaning and lubrication of cylinder  24  of engine  22  is desirably performed via cylinder preparation process  30 . Within process  30 , a task  32  cleans cylinder  24  in an effort to substantially remove contaminants therefrom. In this discussion, “contaminants” are taken to be any remaining metallic debris from the boring and/or honing of cylinder  24 , any soil, any dust, any corrosion, or any other foreign matter in or upon inner surface  26  of cylinder  24 . 
     Cleaning task  32  incorporates a subtask  34  in which cylinder  24  (i.e., block  20  of engine  22 , and therefore cylinder  24  within block  20 ) is cleaned with a solution of water containing a wetting agent in the effort to remove the contaminants from cylinder  24 . The wetting agent may be any of a plurality of soaps and/or detergents. Solution-cleaning subtask  34  serves to clean inner surface  26  of cylinder  24  of a substantial portion of contaminants. 
     Those skilled in the art will appreciate that, in solution-cleaning subtask  34 , engine block  20  may simply be “washed with soap and water.”This washing may be accomplished by immersion, by pressure spay, and/or by scrubbing. This washing may also be accomplished multiple times, may involve multiple wetting agents, and may involve a final clear rinse (i.e., a rinse with water only). These and other variations of solution-subtask  34  do not depart from the spirit of the intended invention. 
     Cleaning task  32  also incorporates a subtask  36  in which cylinder  24  may be further cleaned with a solvent in the effort to remove the contaminants therefrom. The solvent is desirably a volatile solvent (e.g., lacquer thinner, brake cleaner, etc.) which reacts to draw out any water and/or wetting agent residue, as well as other contaminants, thereby serving to dry as well as clean cylinder  24 . Solvent-cleaning subtask  36  serves to penetrate, bring to the surface, and wash away contaminants within inner surface  26  of cylinder  24 . 
     Solvent-cleaning subtask  36  is desirably effected through the use of an absorbent applicator at least partially saturated with the solvent. The use of such an applicator allows contaminants to be wiped away once released by the solvent. Those skilled in the art will appreciate that the absorbent applicator used for solvent-cleaning subtask  36  may be a paper towel, a shop towel, a mop applicator, or any other applicator capable of being at least partially saturated with the requisite liquid. The material of which the applicator is formed is irrelevant to its operation. This material should desirably be absorbent (e.g., can hold a sufficient quantity of the requisite liquid), non-polluting (e.g., is substantially free of lint or other contaminants), and is non-abrasive (e.g., unlikely to scratch or otherwise mar inner surface  26  of cylinder  24 ). The use of variant applicators and/or variant methods of effecting solvent-cleaning subtask  36  (e.g., immersion, wiping, etc.) does not depart from the spirit of the present invention. 
     Following cleaning task  32 , process  30  performs a task  40  to lubricate inner surface  26  of cylinder  24  with a penetrating oil (e.g., ZEPRESERVE [Zep Manufacturing Co.], WD-40 [WD-40 Company], etc.). It is desirable that a penetrating oil be used to allow the lubricant to extend into inner surface  26  of cylinder  24 . 
     Lubricating task  40  is desirably effected through the use of an absorbent applicator at least partially saturated with the penetrating oil. The use of such an applicator allows a substantially uniform coat of penetrating oil to be spread over the entirety of inner surface  26  of cylinder  24 . Those skilled in the art will appreciate that the absorbent applicator of lubricating task  40  may be substantially identical to the absorbent applicator of solvent-cleaning subtask  36 . The use of variant applicators and/or variant methods of effecting lubricating task  40  does not depart from the spirit of the present invention. 
     A task  42  then coats inner surface  26  of cylinder  24  with indicating lubricant  28 . In the preferred embodiment, indicating lubricant  28  is a powder for piston-ring installation. That is, indicating lubricant  28  is a powdered lubricant that coats and penetrates inner surface  26  of cylinder  24 , thereby providing a lubrication that assists in the insertion of a piston and with associated piston rings into cylinder  24  during the assembly of reciprocating engine  22 , and further provides lubrication for those piston rings during engine run-in. 
     Desirably, indicating lubricant is a modified tungsten disulfide lubricant powder. In the preferred embodiment, graphite is the modifying agent. That is, indicating lubricant  28  is a powdered mixture of tungsten disulfide and graphite, WS 2 +C. Both tungsten disulfide and graphite are acceptable lubricants, having low coefficients of friction. 
     Lubricating task  40  is desirably effected immediately prior to coating task  42 . The penetrating oil of lubricating task  40  is then in position on inner surface  26  of cylinder  24 , and acts as a carrier for indicating lubricant  28 . As a carrier, the penetrating oil aids in the even dispersal of indicating lubricant  28  onto and into inner surface  26  of cylinder  24 . That is, the penetrating oil carries indicating lubricant  28  into the pores of the metal of cylinder  24 . 
     Those skilled in the art will appreciate that lubricating task  40  and coating task  42  may be combined into a single task if powdered indicating lubricant  28  is combined with the penetrating oil prior to application. The combining of tasks  40  and  42  does not depart from the spirit of the present invention. 
     The chemical properties of indicating lubricant  28  are such that indicating lubricant  28  assumes a “clean” tint uniformly over inner surface  26  of cylinder  24  when indicating lubricant  28  detects that cylinder  24  is substantially free of contaminants. That is, if cleaning task  32  (i.e., solution-cleaning subtask  34  and solvent-cleaning subtask  36 ) has cleaned substantially all contaminants from the entirety of inner surface  26  of cylinder  24 , indicating lubricant  28  will assume the clean tint. In the preferred embodiment, the clean tint is a greenish tint different from the base tint (i.e., pre-application tint) of powdered indicating lubricant  28 . In the preferred embodiment where indicating lubricant  28  is a tungsten disulfide plus graphite mixture, the base tint is a neutral gray. 
     Conversely, indicating lubricant  28  does not assume the clean tint (i.e., does assume a “dirty” tint) when indicating lubricant  28  detects that cylinder  24  has contaminants. That is, if cleaning task  32  (i.e., solution-cleaning subtask  34  and solvent-cleaning subtask  36 ) has not cleaned substantially all contaminants from inner surface  26  of cylinder  24 , indicating lubricant  28  will assume the dirty tint. In the preferred embodiment, the dirty tint may be the base (grayish) tint of indicating lubricant  28 , or may be a blackish or silvery tint if indicating lubricant  28  reacts with the contaminants. It is the assumption of the clean tint that differentiates powdered indicating lubricant  28  from prior art. The clean tint provides simultaneous indication of both the cleanliness of inner surface  26  of cylinder  24  and the distribution of indicating lubricant  28  over that inner surface  26 . By uniformly changing from the base tint to the clean tint (i.e., exhibiting no dirty tint), indicating lubricant  28  provides visual verification that inner surface  26  of cylinder  24  has been cleaned of substantially all contaminants. Likewise, by changing to the clean tint over the entirety of inner surface  26 , indicating lubricant provides visual verification that no portion of inner surface  26  has been omitted in coating task  42 . 
     In a query task  44 , process  30  determines if indicating lubricant  28  has assumed the clean tint. If query task  44  determines that indicating lubricant  28  has not assumed the clean tint (i.e., has assumed the dirty tint because contaminants were detected), then process  30  repeats cleaning task  32 , lubricating task  40 , and coating task  42  in an effort to remove substantially all contaminants from inner surface  26  of cylinder  24 . This is repeated until query task determines that indicating lubricant  28  has assumed the clean tint. 
     If query task  44  determines that indicating lubricant  28  has assumed the clean tint (i.e., contaminants were not detected), then the assembly of reciprocating engine  22  may proceed. 
     Prior to the assembly of reciprocating engine  22 , process  30  effects a task  46  in which the piston rings (not shown) to be used in cylinder  24  are prelubricated with a lightweight oil, e.g., mineral oil or SAE  10  motor oil, to facilitate insertion of the rings into cylinder  24 . Task  46  is contrary to conventional practice, where the piston rings are inserted dry. It is the use of indicating lubricant  28  that makes task  46  feasible. Process  30  then effects a final task  48  allowing the assembly of reciprocating engine  22  to proceed. That is, the post-honing, pre-assembly preparation of cylinder  24  is complete. 
     Indicating lubricant  28 , with assistance from the penetrating oil of lubricating task  40 , coats inner surface  26  of cylinder  24  with a fine, penetrating lubricant suitable for engine run-in. That is, indicating lubricant  28  will remain in cylinder  24  during engine run-in, thereby significantly reducing engine wear during this critical operation. 
     The use of indicating lubricant  28  significantly reduces the time required for seating of the piston rings into cylinder  24  during run-in. Such seating is substantially immediate, further reducing run-in wear. 
     In summary, the present invention teaches a post-honing reciprocating-engine cylinder preparation process  30  using a powder for piston-ring installation. A cleaning task  32  within process  30  cleans cylinder  24  to remove substantially all contaminants therefrom. A coating task  42  within process  30  coats inner surface  26  of cylinder  24  with a powdered indicating lubricant  28 . Indicating lubricant  28  provides an indication of the cleanliness of cylinder  24  prior to engine assembly. Indicating lubricant  28  also provide a penetrative and dry lubrication of cylinder  24  to aid in the installation of a piston and associated piston rings into cylinder  24  during assembly of reciprocating engine  22 . Indicating lubricant  28  also aids in the inhibition of excessive wear and tear of engine  22  during run-in. 
     Although the preferred embodiments of the invention have been illustrated and described in detail, it will be readily apparent to those skilled in the art that various modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.