Patent Application
20100011847
The present invention relates generally to engine diagnostics. More particularly, the present invention relates to internal combustion engine cylinder compression testers.
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 lbs. per square inch, 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 and 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 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, back firing 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 used in certain Ford trucks utilizes 16 mm nominal threads. In addition the spark plug sockets on the Ford Triton® three-valve V8 engines are located in spark plug wells that are relatively deep and, the spark plug sockets include a sealing surface at the inner end of the socket. U.S. Pat. No. 7,216,531 issued May 15, 2007 to Young et al provides a method and apparatus that permits compression testing of an engine exclusively with 16 mm nominal threaded spark plug sockets located in relatively deep spark plug wells that have a sealing surface at the inner end of the socket.
After several years of using 16 mm spark plugs in the Ford Triton® three-valve V8 engine line, a service problem arose. It was discovered that when the 16 mm spark plugs were removed, they would break off leaving a piece stuck in the cylinder head. This created a major problem since the cylinder head has to be removed from the engine to retrieve the broken spark plug part. To further compound this problem, the engine has to be removed or the truck body separated from the vehicle frame to remove the cylinder head since one-third of the cylinder head is tucked beneath the vehicle firewall. This is an expensive problem to rectify typically costing $1,500 minimum in service costs. In order to resolve the problem of 16 mm spark plug breakage, Ford redesigned their engines to use a 12 mm spark plug of conventional design which will not break off when removed.
Accordingly, it is desirable to provide an adapter assembly having a dual purpose adapter that permits compression testing of internal combustion engines that are designed with either 16 mm or 12 mm nominal spark plug sockets located in relatively deep spark plug wells that have sealing surfaces therein. It is also desirable to provide a method of measuring compression pressure in an individual cylinder of an internal combustion engine employing either a 12 mm or 16 mm thread spark plug socket.
Providing an adapter assembly that facilitates compression testing of an internal combustion engine that has 16 mm or 12 mm spark plugs poses a particular challenge because of the nature of the spark plug sockets located in relatively deep spark plug wells having sealing surfaces at the inner ends of the sockets. An adapter provided for use with both the 16 mm and 12 mm spark plug sockets needs to be uniquely designed so that it will threadably and sealingly engage the particular spark plug socket in a proper manner to enable accurate compression testing without causing mechanical interference in the socket.
The present invention relates to a compression tester adapter assembly used with both 12 millimeter and 16 millimeter spark plug sockets in an internal combustion engine cylinder head. The assembly includes an adapter having a leading cylindrical portion including one set of external threads configured with a nominal diameter of 12 millimeters, and a trailing cylindrical portion spaced from the leading cylindrical portion and including another set of external threads configured with a nominal diameter of 16 millimeters. The axial spacing between a first leading full thread on the 12 millimeter threads and a first leading full thread on the 16 millimeter threads lies in the range of 0.636-0.737 inches. The assembly also includes a connector and a hose having opposite ends attached to the adapter and the connector.
The adapter includes a cylindrical head spaced from a trailing thread on the 16 millimeter threads, and a hose connector end extending from the cylindrical head. The adapter further includes one gasket seat located between the leading and trailing cylindrical portions. The adapter also includes one other gasket seat located between the cylindrical head and the trailing cylindrical portion. One gasket is fitted in the one gasket seat and configured to form a seal against a sealing surface spaced from an upper end of the 12 millimeter spark plug socket. One other gasket is fitted in the other gasket seat and configured to form a seal against a sealing surface adjacent the upper end of the 16 millimeter spark plug socket. The 12 millimeter threads are formed substantially along an entire axial length of the leading cylindrical portion. The 16 millimeter threads are formed partially along an axial length of the trailing cylinder portion. An outer diameter of the leading cylinder portion is less than the outer diameter of the trailing cylinder portion.
An outer diameter of the cylindrical head is larger than an outer diameter of the trailing cylindrical portion. The adapter further includes an elongated airway extending longitudinally therethrough. The airway is formed with an enlarged chamber for receiving a valve core adapted to permit air flow through the airway in one direction only. The assembly further includes a first ferrule configured to engage an outer surface of the hose at one end thereof. A second ferrule is configured to engage an outer surface of the hose at another end thereof. The first ferrule is crimped onto the hose connector end at one end thereof to affix the hose to the adapter, and the second ferrule is crimped onto a hose connector end of the connector to affix the hose to the connector. The hose has a hollow central passage providing uninterrupted sealed fluid communication between the adapter and the connector. The connector is connected to a compression tester hose assembly having a compression pressure gauge. The 12 millimeter threads are configured to be threaded into a 12 millimeter spark plug socket causing the one gasket to form the seal spaced from the upper end thereof without interference with the 16 millimeter threads. The 16 millimeter threads are configured to be threaded into the 16 millimeter spark plug socket causing the other gasket to form the seal adjacent the upper end thereof without interference from the 12 millimeter threads.
The invention further contemplates a method of measuring compression pressure in an individual cylinder of an internal combustion engine employing either a 12 millimeter or 16 millimeter threaded spark plug socket. The method includes the steps of providing an adapter having a leading cylindrical portion including one set of external threads configured with a nominal diameter of 12 millimeters, and a trailing cylindrical portion spaced from the leading cylindrical portion and including another set of external threads configured with a nominal diameter of 16 millimeters, wherein axial spacing between a first leading full thread on the 12 millimeter threads and a first leading full thread on the 16 millimeter threads lies in the range of 0.636-0.737 inches, a connector, and a hose having opposite ends attached to the adapter and connector, the adapter including a cylindrical head spaced from a trailing thread on the 16 millimeter threads, one gasket located between the leading and trailing cylindrical portions and one other gasket located between the cylindrical head and the trailing cylindrical portion; engaging the 12 millimeter or 16 millimeter threaded spark plug socket with matching external threads formed on the adapter so as to form a seal between one of the gaskets and a sealing surface near the upper end of the spark plug socket; attaching a compression tester spark plug hose and a compression pressure gauge to the connector; and transmitting a compressed gas to the compression tester spark plug hose and a compression pressure gauge.
Referring now to
The adapter assembly 16 and the compression tester hose 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.
An embodiment of the adapter assembly 16 is shown in
In a preferred embodiment, the flexible hose 24 is about 3/16″ in diameter and about 10″ long. This length permits access to a spark plug socket located at the bottom of a relatively deep spark plug well, for example, greater than 2″ deep. This configuration has the advantage that the tester 10 can be used to reach a spark plug socket in a Ford Triton® three valve engine including the 4.6 and 5.4 liter V8 versions as well as a 6.8 liter V10 version. The adapter 22 and the quick disconnect coupling 23 are fixedly joined to opposite ends of the flexible hose 24 using aluminum ferrules 29 which are crimped upon the hose 24 as shown in
As shown in
As seen best in
In accordance with the invention, the adapter 22 is designed with critical dimensions so that it may be threadably and sealingly engaged in a proper manner in either an internally threaded 16 millimeter or 12 millimeter spark plug socket recessed relatively deep within the spark plug chamber of an internal combustion engine cylinder head 20.
The adapters 22, 22a are formed such that the axial spacing between the first full thread 66 of the 12 millimeter threads set 54 and the first full thread 68 of the 16 millimeter thread set 46 falls within the critical range of 0.636″-0.737″.
In the preferred embodiments, the external threads 46 of the adapters 22, 22a are configured in accordance with the international standards (ISO) specification 261 metric 16 millimeter nominal thread standard M16×1.5. The external threads 54 of the adapter 22 and 22a are configured in accordance with the international standard (ISO) specification 261 metric 12 millimeter nominal thread standard M12×1.25. External thread set 46 is formed partially along the axial length of the first cylindrical portion 44, and the external thread set 54 extends substantially the entire axial length of second cylindrical portion 52.
The ends 56 of the adapters 22, 22a are machined with a slight chamfered edge to prevent damage to the adapters 22, 22a or the spark plug socket threads when the adapters 22, 22a are inserted into the spark plug socket.
The adapters 22, 22a facilitate the use of an existing compression tester with either a 16 millimeter or 12 millimeter spark plug socket for an engine such as including the Ford Triton® V8 and V10 engine family.
The adapters 22 or 22a and quick disconnect coupling 23 are attached to the flexible hose 24 by inserting the respective hose connector ends 30 and 25 into opposite ends of the flexible hose 24 and crimping the ferrules 29 over the exterior of the hose 24 to compress the hose 24 over the hose connector ends 30 and 25. Thus, the adapter 22 or 22a and the coupling 23 are fixedly attached to the flexible hose 24 so that the adapter 22 or 22a can be threaded into a spark plug socket by manually rotating the assembly 16 by way of the knurl normally formed on the exterior of the coupling 23. The assembly 10 provides a continuous uninterrupted sealed or air tight fluid communication path between the orifice 32 in adapter 22 or 22a and the airway 26 terminating on the upper end of coupling 23.
The present invention thus provides an adapter assembly 16 having an adapter 22, 22a that can be threadably and sealingly engaged either in a 12 millimeter or 16 millimeter spark plug socket 70 or 72 recessed relatively deep in an internal combustion engine cylinder head 20 without causing mechanical interference therein. The adapter 22, 22a may have a variable overall length and a variable number of threads in the 16 millimeter or 12 millimeter thread sets 46 or 54 as long as the spacing between the first full thread of the 12 millimeter thread set 54 and the first full thread of the 16 millimeter thread set 46 lies in the critical range of 0.636″-0.737″.
While the invention has been described with reference to a preferred embodiment, those skilled in the art will appreciate that certain substitutions, alterations and omissions may be made without departing from the spirit thereof. Accordingly, the foregoing description is meant to be exemplary only and should not be deemed limitative on the scope of the invention set forth with the following claims.
