Abstract:
A compression tester adapter is provided. The compression adaptor includes a generally cylindrical plug fitting, including a pilot segment, an external thread, a cylinder segment, a gasket located between the external thread and the cylinder segment and a plug end; and a connector fitting including an attachment interface; and a hose attached to the plug fitting. A method of adapting a compression tester spark plug hose for use with a spark plug socket is provided. The method includes; engaging a threaded spark plug socket in an internal combustion engine cylinder head; attaching a compression tester spark plug hose; and transmitting a compressed gas to the compression tester spark plug hose wherein the spark plug socket thread is configured with a nominal diameter of 12 millimeters; and creating a substantially airtight seal against a periphery of a tapered seat near a inner extreme of the spark plug socket.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to engine diagnostics. More particularly, the present invention relates to internal combustion engine cylinder compression testers. 
     BACKGROUND OF THE INVENTION 
     Compression testers are used to measure the compression pressure in an individual cylinder of an internal combustion engine. A typical compression tester consists of a compression pressure gauge with a pressure measurement range of, for example, 0-300 pounds per square inch (psig), and a compression pressure hose assembly that attaches to the compression pressure gauge. Typically, the compression tester hose assembly connects to a spark plug socket in an engine cylinder head. Thus, the spark plug is removed from the cylinder head, and the compression tester hose assembly is threaded into the spark plug hole, or socket, in order to establish fluid communication between the compression pressure gauge and the engine cylinder. The engine is then cranked for several revolutions, typically using the engine starter, in order to measure the maximum compression pressure in the engine cylinder. 
     The compression pressure is used to test internal combustion engines for proper compression in each cylinder. Improper compression can cause rough idling or running, backfiring and poor fuel economy. Low compression in a cylinder can be an indication of worn or damaged piston rings, valves, head gasket or timing chain. A high compression reading may indicate carbon buildup in the cylinder. If the compression pressure gauge remains at the same value for several strokes and then begins to climb, the cylinder may have a sticking valve. 
     Standard spark plug sockets typically include 14-millimeter (mm) nominal threads, 18-mm nominal threads, 12-mm nominal threads or 10-mm nominal threads. However, some newer engines utilize other spark plug thread sizes. For example, the Ford Triton™ three-valve V8 engine family utilizes 12-mm nominal threads. 
     SUMMARY OF THE INVENTION 
     The foregoing needs are met, to a great extent, by the present invention, wherein in one aspect an apparatus is provided that in some embodiments facilitates compression testing of an engine that includes 12-mm nominal spark plug sockets. 
     In accordance with another embodiment of the present invention, a compression tester adapter is provided. The compression adaptor includes a generally cylindrical plug fitting, including a flange segment, an external thread, a cylinder segment, a gasket located between the external thread and the cylinder segment and a plug end; and a connector fitting including an attachment interface; and a hose attached to the plug fitting. 
     In accordance with another embodiment of the present invention, a compression tester adapter is provided. The compression adaptor includes means for engaging a threaded spark plug socket in an internal combustion engine cylinder head; means for attaching a compression tester spark plug hose; flexible means for transmitting a compressed gas; means for affixing the flexible means for transmitting to the means for engaging; means for affixing the flexible means for transmitting to the means for attaching wherein the means for engaging is configured to engage an internal thread configured with a nominal diameter of 12 millimeters; and means for creating a substantially airtight seal against a periphery of a tapered seat near a inner extreme of the spark plug socket. 
     In accordance with yet another embodiment of the present invention, a method of adapting a compression tester spark plug hose for use with a spark plug socket is provided. The method includes; engaging a threaded spark plug socket in an internal combustion engine cylinder head; attaching a compression tester spark plug hose; and transmitting a compressed gas to the compression tester spark plug hose wherein the spark plug socket thread is configured with a nominal diameter of 12 millimeters; and creating a substantially airtight seal against a periphery of a tapered seat near a inner extreme of the spark plug socket. 
     There has thus been outlined, rather broadly, certain embodiments of the invention in order that the detailed description thereof herein may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional embodiments of the invention that will be described below and which will form the subject matter of the claims appended hereto. 
     In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of embodiments in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting. 
     As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an exemplary compression tester configuration including a compression tester adapter according to a preferred embodiment of the invention. 
         FIG. 2  is a side view illustrating the compression tester adapter of  FIG. 1 . 
         FIG. 3  is a side view similar to  FIG. 2 , however,  FIG. 3  illustrates the internal passages. 
         FIG. 4  is a side view of a plug fitting that is compatible with the compression tester adapter of  FIG. 2 . 
         FIG. 5  is a side view of a connector fitting that is compatible with the compression tester adapter of  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION 
     The invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. An embodiment in accordance with the present invention provides a compression tester adapter to adapt a standard compression tester hose assembly for connection to 12-millimeter (mm) nominal threaded spark plug socket. The compression tester adapter includes a plug fitting, a connector fitting, and a flexible hose connected to the plug fitting and to the connector fitting, providing uninterrupted sealed fluid communication between an orifice in the plug fitting and an attachment interface on the connector fitting. 
     An embodiment of the present inventive apparatus and method is illustrated in  FIG. 1 .  FIG. 1  shows a compression tester  10  including a compression pressure gauge  12 , a compression tester hose assembly  14  and a compression tester adapter  16 . The compression tester adapter  16  allows the standard compression tester hose assembly  14  to be connected to a spark plug socket  18  with 12-mm nominal threads in an internal combustion engine cylinder head  20 . 
     The compression tester adapter  16  and the compression tester hose assembly  14  permit connection of the compression pressure gauge  12  to the cylinder head  20  in order to provide fluid communication between a cylinder in the engine and the compression pressure gauge  12 . Thus, when the engine is cranked through, typically, three or more revolutions, the compression pressure gauge  12  senses the maximum compression pressure developed in the engine cylinder. A typical compression pressure gauge  12  is capable of measuring pressures in a range, for example, from 0-300 psig. 
     An embodiment of the compression tester adapter  16  is shown in  FIGS. 2 and 3 . The compression tester adapter  16  includes a plug fitting  22  and a connector fitting  24 , which are connected to the two ends of a flexible hose  26 . In an embodiment of the invention, the flexible hose  26  is approximately 4.31 inches in length, permitting access to a spark plug socket located at the bottom of a relatively deep spark plug well, for example, greater than two inches deep. This configuration has the advantage that a compression tester  10  (see  FIG. 1 ) can be adapted to reach the spark plug socket  18  in, for example, a Ford Triton™ three-valve engine, including the 4.6 liter and 5.4 liter V8 versions. 
     As shown in  FIGS. 2 and 3 , the compression tester adapter  16  plug fitting  22  includes a cylinder segment  42  with external threads  30  configured to engage 12-mm nominal size internal threads, and an orifice  32  to permit entry of compressed air from an engine cylinder into the compression tester adapter  16 . The plug fitting  22  is fixedly attached to the flexible hose  26  using a crimped ferrule  34 . 
     The compression tester adapter  16  also includes a connector fitting  24 , which has a diamond knurl  36  on its exterior surface to aid in manual rotation of the compression tester adapter  16  in order to thread the plug fitting  22  into a spark plug socket  18  (see  FIG. 1 ). The connector fitting  24  is fixedly attached to the flexible hose  26  with a crimped ferrule  40 , and includes an attachment interface  38 . In some embodiments of the invention, the attachment interface  38  includes internal threads, for example, 14-mm or any other sized nominal threads. The attachment interface  38  permits attachment of the compression tester adapter  16  to a standard compression tester hose assembly  14  (see  FIG. 1 ), such as those included with the OTC Models 5605 and 5606, and the Actron® Models CP7828 and CP7827, manufactured by SPX Corporation of North Carolina, U.S.A. 
       FIG. 4  illustrates a plug fitting  22  in accordance with an embodiment of the invention. The plug fitting  22  includes a pilot segment  42  near the plug end that is inserted into the spark plug socket  18  (see  FIG. 1 ). The pilot segment  42  provides a guide surface to center the plug fitting  22  in a spark plug socket. The plug fitting  22  also includes a gasket seat  44  with the same, larger or smaller diameter than that of the pilot segment  42  between the threads  30  and a cylinder segment  28 . 
     In one example embodiment, plug fitting  22  includes a pilot segment  42  with a diameter of approximately 0.375 inch, a gasket seat  44  with a diameter of approximately 0.39 inch, and a cylinder segment  28  with a diameter of approximately 0.55 inch. In this example embodiment, the pilot segment  42  is approximately 0.21 inch wide with a 0.03 inch 45° chamfer  64  at the plug end, the gasket seat  44  is approximately 0.156 inch wide, and the cylinder segment  28  is approximately 0.25 inch wide with a 0.03 inch 45° chamfer  66  at its plug end. (Alternatively, these widths could be referred to as axial lengths.) 
     A 12-mm nominal metric external thread  30 , or threads, which may be configured generally in compliance with International Standards Organization (ISO). Specifications may be machined into the external surface of the rim segment  46 . The plug fitting  22  also includes a rim segment  46  with a larger diameter than that of the cylinder segment  28 . At the end of the plug fitting  22  opposite the pilot segment  42  is a tube end  48  of the plug fitting  22 , which includes a tube segment  50  and a hose connector segment  54 . The tube segment  50  includes a straight knurl  52  and the hose connector segment  54  includes a serration profile  56 , which aid in attaching the flexible hose  26  (see  FIG. 2 ) to the plug fitting  22 . 
     The plug fitting  22  further includes an internal airway  58 , comprising a cylindrical bore, for example, of 0.110 inch diameter, through the center of the plug fitting  22  along its longitudinal axis with an orifice  60  at the plug, or pilot, end and an opening  62  at the tube end  48 . The plug end of the pilot segment  42  and the cylinder segment  28  are machined with chamfered edges  64 ,  66  to prevent damage to the plug fitting  22  or to the spark plug socket threads when the plug fitting is inserted into the spark plug socket. 
     The plug fitting is configured to accommodate a gasket  68  at the gasket seat  44  to seal against a tapered edge at the bottom of the spark plug socket  18  (see  FIG. 1 ). The gasket  68  is retained by the threads  30  and the cylinder segment  28 . In one embodiment, the plug fitting  22  includes an O-ring type gasket  68  made from a resilient material that conforms to the gasket seat  44  surface, such as a natural or artificial rubber, or an elastomer, which provides for an air tight seal against the tapered bottom edge of the spark plug socket  18  to facilitate measurement of the maximum compression pressure developed in the engine cylinder. 
     The 12-mm nominal external threads  30  on the plug fitting  22  shown in  FIG. 4  have a pitch diameter, a crest or external diameter, or a root or internal diameter of approximately 12-mm and a shape similar to that of the threads on a spark plug. However, the precise diameter and shape of the external threads  30  on the plug fitting  22  depend on the specification or standard required by the design of the compression tester adapter in order to mate with the threads of a particular spark plug socket adapter  18  (see  FIG. 1 ). In embodiments of the invention, the external threads  30  of the plug fitting  22  are configured in accordance with the International Standards Organization (ISO) specifications. Other embodiments of the invention may include variations of this thread standard or another 12-mm nominal thread standard. The compression tester adapter facilitates the use of an existing compression tester with an engine including a 12-mm nominal spark plug socket, such as the Ford Triton™ three-valve V8 engine family. 
     An embodiment of the connector fitting  24  is illustrated in  FIG. 5 . The connector fitting  24  includes a cylinder segment  70  with a diamond knurl  36  machined on the external surface of the cylinder segment  70 . The cylinder segment  70  includes a chamfered edge at each end  72 ,  74 . Some embodiments of the invention include a socket  76  with internal threads  78  to provide an attachment interface  38 . 
     Some embodiments of the compression tester adapter include a connector fitting  24  with internal threads  78  configured in accordance with the International Standards Organization (ISO) specifications. Various embodiments of the compression tester adapter include an attachment interface  38  or socket  76  with different sized standard threads, for example, 14-mm nominal threads. 
     The socket  76  opens into an internal airway  80 , comprising a cylindrical bore, for example, of 0.110 inch diameter, through the center of the connector fitting  24  along its longitudinal axis with an opening  82  at the opposite or tube end of the connector fitting  24 . At this end of the connector fitting  24  is a tube end  84  comprising a tube segment  86  and a hose connector segment  88 . The tube segment  86  includes a straight knurl  90  and the hose connector segment  88  includes a serration profile  92 , which aid in attaching the flexible hose  26  (see  FIG. 2 ) to the connector fitting  24 . 
     Although the connector fitting  24  shown in  FIG. 5  includes a socket  76  with internal threads  78 , the attachment interface  38  of the connector fitting  24  in other embodiments may include any suitable connector interface, for example, a quick-disconnect coupling connector of the type used on some existing compression tester assemblies, such as the Actron™ Models CP7828 and CP7827 manufactured by SPX Corporation of North Carolina, U.S.A. 
     In an embodiment of the compression tester adapter, the plug fitting and the connector fitting are machined from cold-rolled carbon steel, and include a bright nickel plate finish. However, in other embodiments these fittings may include any suitable material, such as brass, cast iron, or the like. 
     Referring again to  FIG. 2 , the flexible hose  26  includes a hollow central passage of generally cylindrical shape along the longitudinal axis of the flexible tube  26  to transmit compressed air from the plug fitting  22  to the connector fitting  24 , and thus to the compression pressure gauge  12  (see  FIG. 1 ). The compression tester adapter provides a continuous uninterrupted sealed, or airtight, fluid communication path between the orifice  32  in the plug fitting  22  and the attachment interface  38  of the connector fitting  24 . 
     The plug fitting  22  and the connector fitting  24  are attached to the flexible hose  26  by inserting the tube ends  48 ,  84  (see  FIG. 4  and  FIG. 5 ) into both ends of the flexible hose  26  and crimping steel ferrules  34 ,  40  over the exterior of the flexible hose  26  to compress the flexible hose  26  over the tube ends  48 ,  84  (see  FIG. 4  and  FIG. 5 ). Thus, the connector fitting  24  and the plug fitting  22  are fixedly attached to the flexible hose  26  so that the plug fitting  22  can be threaded into a spark plug socket by manually rotating the compression tester adapter by way of the diamond knurl  36  exterior surface of the connector fitting  24 . The various embodiments including a flexible hose  26  have the advantage that the compression tester adapter can be installed in a spark plug socket that is not accessible with a straight, rigid, one-piece adapter fitting. 
     The flexible hose  26  is made of an oil- and grease-resistant material, such as a natural or artificial rubber, or polymer, and includes one or more internal reinforcement sleeves including a braid or mesh oriented on the bias, that is, approximately at a 45-degree diagonal with respect to the longitudinal axis of the flexible tube  26 . A preferred embodiment of the invention includes two textile braid reinforcements between an inner tube of seamless nitrile rubber and an outer jacket of neoprene. An alternative embodiment includes two metallic mesh reinforcement sleeves. Other embodiments may include any suitable reinforcement sleeve configurations, including one or more textile or metallic braid or mesh reinforcement sleeves. In some embodiments the textile or metallic braid or mesh may be oriented at a different orientation, for example, parallel to the longitudinal axis of the flexible tube  26  or at a different angle, for example, at a 30-degree angle with the longitudinal axis of the flexible tube  26 . Furthermore, another alternative embodiment of the invention includes a flexible hose made of a single flexible material and does not include a reinforcement sleeve. 
     The various embodiments of the invention that include a textile or metallic braid or mesh reinforcement sleeve, or multiple reinforcement sleeves, have the advantage that the reinforcement sleeve transfers the torque or moment placed upon the connector fitting  24  when the diamond knurl  36  exterior surface is rotated in order to thread the plug fitting  22  external threads  30  into a spark plug socket. Thus, the reinforcement sleeve carries the majority of the torque or moment loading when the compression tester adapter is tightened into or loosened from a spark plug socket. 
     An alternative embodiment of the invention includes a plug fitting end and a connector fitting end machined from a single metal stock. In this embodiment, one end of the compression tester adapter  16  is configured with the features described above for on the plug fitting  22  of  FIG. 4 , except for the tube end  48 , which is not included; the opposite end is configured with the features described above for the connector fitting  24  of  FIG. 5 , except for the tube end  84 , which is not included. Thus, this embodiment does not include a flexible hose, but rather comprises a single, rigid, machined fitting with a plug end and a connector end. 
     The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.