Engine cylinder liner having a mid stop

A replaceable liner for use in an internal combustion engine containing a liner receiving cavity extending between the engine head and a crankshaft to which a piston is connected for reciprocating travel within the liner receiving cavity and having a liner stop positioned intermediate the ends of the liner receiving cavity and a liner coolant passage formed to provide coolant to the outer surface of the liner, comprising

• (a) a substantially cylindrical outer end portion having a piston engaging inside surface for guiding the piston during one portion of reciprocating piston travel leading to and from the outer limit of piston travel and a top end face for forming a combustion gas seal with the engine head, said cylindrical outer end portion including
• (1) securing means for preventing radial movement of said outer end portion while permitting limited axial movement of the outer end portion within the liner receiving cavity by forming a radial press fit with the inside surface of the liner receiving cavity by compressively and frictionally engaging the inside surface of the liner receiving cavity when pressed thereinto, said securing means including an end boss adjacent the outermost end of said cylindrical outer end portion, said end boss having an outside cylindrical surface extending inwardly from said top end face, said outside cylindrical surface having a diameter slightly greater than the inside diameter of the liner receiving cavity adjacent said end boss to form a coolant impervious press fit completely around said end boss between the inside surface of the liner receiving cavity and the liner when the liner is placed within the liner receiving cavity, said end boss being free of any engine engaging radial surface thereby permitting axial movement of the outermost end of said outer end portion within the liner receiving cavity,
• (2) stop means for retaining the innermost end of said outer end portion against axially inward movement relative to the liner receiving cavity, said stop means including a stop boss adjacent the innermost end of said outer end portion, said stop boss including a radially oriented stop engaging surface continuously engaging the liner stop when said liner is placed within the liner receiving cavity to form a substantially coolant impervious seal when the liner is biased with sufficient force against the liner stop, and
• (3) an annular recess formed in the outside surface of said cylindrical outer portion and extending over substantially the entire axial distance between said end boss and said stop boss to form one wall of the liner coolant passage when the liner is placed within the engine, said annular recess extending over no more than approximately 30% of the total axial length of the liner;
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• (b) a cylindrical inner end portion integrally joined with said outer end portion, said inner end portion having a piston engaging inside surface which is a continuation of said piston engaging inside surface of said outer end portion for guiding piston movement during the remaining portion of the reciprocal piston movement, said inner end portion being free of direct supporting and heat conducting contact between said inner end portion and the inside surface of the liner receiving cavity, said inner end portion having an axial length equal to at least 30 percent of the total length of said inner and outer end portions.

A replaceable liner for use in an internal combustion engine including a head and a block having a head engaging surface and a liner receiving cavity extending between the head engaging surface and a crankshaft to which a piston is connected for reciprocating travel within the liner and having a liner stop positioned approximately in the midsection of the liner receiving cavity and a liner coolant passage formed to provide coolant to the outer surface of the liner, comprising:

• (a) a hollow cylindrical body formed of material having predetermined resilient characteristics including an outer end portion having a piston engaging inside surface for guiding piston movement to and from the outer limits of piston travel and a top end face for forming a combustion gas seal with the engine head and including an inner end portion having a piston engaging inside surface which is a continuation of said piston engaging inside surface of said outer end portion for guiding piston movement during the remaining portion of the reciprocal piston movement, said inner end portion being free of direct supporting and heat conducting contact between said inner end portion and the engine block, said inner end portion having an axial length equal to at least 30 percent of the total length of said inner and outer end portions;
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• (b) positioning means utilizing the resilient characteristics along the entire axial length of said outer end portion to maintain an adequate combustion gas seal between said top end face and the engine head, said positioning means including
• (1) securing means for preventing radial movement of said outer end portion while permitting limited axial movement of the outer end portion within the cylindrical cavity by forming a radial press fit with the inside surface of the liner receiving cavity by compressively and frictionally engaging the inside surface of the liner receiving cavity when pressed thereinto, said securing means including an end boss adjacent the outermost end of said outer end portion, said end boss having an outside cylindrical surface extending axially inwardly from said top end face, said outside cylindrical surface having a diameter slightly greater than the inside diameter of the liner receiving cavity adjacent the head engaging surface to form a coolant impervious press fit completely around said end boss between the engine block and the liner when the liner is placed within the liner receiving cavity, said end boss being free of any block engaging radial surfaces thereby permitting axial movement of the outermost end of said outer end portion within the liner receiving cavity, and
• (2) stop means for retaining the innermost end of said outer end portion against axially inward movement relative to the liner receiving cavity, said stop means including a stop boss adjacent the innermost end of said outer end portion, said stop boss including an outside diameter smaller than the outside diameter of said end boss, said stop boss including a radially oriented stop engaging surface continuously engaging the liner stop when said liner is placed within the liner receiving cavity to form a substantially coolant impervious seal when the liner is biased with sufficient force against the liner stop, said stop engaging surface being positioned to cause said outer end portion to extend a predetermined distance beyond the head engaging surface of the engine block when said stop engaging surface is placed in contact with the liner stop;
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• wherein said outer end portion contains an annular recess formed in the outside surface of said outer portion and extending over substantially the entire axial distance between said end boss and said stop boss to form one wall of the liner coolant passage when the liner is placed within the engine block, said annular recess extending over no more than approximately 30% of the total axial length of the liner.