Cylinder liner and method for manufacturing the same

A cylinder liner for insert casting used in a cylinder block, comprising:

• first portion corresponding to a high temperature region;
• a second portion corresponding to a low temperature region;
• and
• a film formed on an outer circumferential surface of the second portion,
• the film being made of a mold release agent that reduces the adhesion between the cylinder liner and the cylinder block so that gaps are formed between the cylinder block and the cylinder liner, thereby reducing a thermal conductivity between the cylinder block and the cylinder liner;
• wherein the cylinder block and the cylinder liner are bonded to each other from a top surface of the cylinder to a bottom surface of the cylinder, and
• wherein the film is made of a material that remains bonded to the second portion of the cylinder liner.

A cylinder liner for insert casting used in a cylinder block, comprising:

• first portion corresponding to a high temperature region;
• a second portion corresponding to a low temperature region;
• and
• a film formed on an outer circumferential surface of the second portion, the film being made of a low adhesion agent containing graphite as a major component that reduces the adhesion between the cylinder liner and the cylinder block so that gaps are formed between the cylinder block and the cylinder liner, thereby reducing a thermal conductivity between the cylinder block and the cylinder liner;
• wherein the cylinder block and the cylinder liner are bonded to each other from a top surface of the cylinder to a bottom surface of the cylinder, and
• wherein the film is made of a material that remains bonded to the second portion of the cylinder liner.

A cylinder liner for insert casting used in a cylinder block, comprising:

• first portion corresponding to a high temperature region;
• a second portion corresponding to a low temperature region;
• and
• a film formed on an outer circumferential surface of the second portion, the film being made of a high temperature resin as a major component that reduces the adhesion between the cylinder liner and the cylinder block so that gaps are formed between the cylinder block and the cylinder liner, thereby reducing a thermal conductivity between the cylinder block and the cylinder liner;
• wherein the cylinder block and the cylinder liner are bonded to each other from a top surface of the cylinder to a bottom surface of the cylinder, and
• wherein the film is made of a material that remains bonded to the second portion of the cylinder liner.

A cylinder liner for insert casting used in a cylinder block, comprising:

• first portion corresponding to a high temperature region;
• a second portion corresponding to a low temperature region;
• and
• a film formed on an outer circumferential surface of the second portion, the film being made of a chemical conversion treatment layer as a major component that reduces the adhesion between the cylinder liner and the cylinder block so that gaps are formed between the cylinder block and the cylinder liner, thereby reducing a thermal conductivity between the cylinder block and the cylinder liner;
• wherein the cylinder block and the cylinder liner are bonded to each other from a top surface of the cylinder to a bottom surface of the cylinder, and
• wherein the film is made of a material that remains bonded to the second portion of the cylinder liner.

A cylinder liner for insert casting used in a cylinder block, comprising:

• first portion corresponding to a high temperature region;
• a second portion corresponding to a low temperature region;
• and
• a film formed on an outer circumferential surface of the second portion, the outer circumferential surface having a plurality of projections, each projection having a constricted shape, the film having a thermal conductivity lower than that of at least one of the cylinder block and the cylinder liner, and the film adapted to reduce a thermal conductivity between the cylinder block and the cylinder liner,
• wherein the cylinder block and the cylinder liner are bonded to each other from a top surface of the cylinder to a bottom surface of the cylinder, and
• wherein the film is made of a material that remains bonded to the second portion of the cylinder liner.

A cylinder liner for insert casting used in a cylinder block, comprising:

• first portion corresponding to a high temperature region;
• a second portion corresponding to a low temperature region;
• and
• a film formed on an outer circumferential surface of the second portion extending from a middle portion to a lower end of the cylinder liner with respect to an axial direction of the cylinder liner, the film having a thermal conductivity lower than that of at least one of the cylinder block and the cylinder liner, and the film adapted to reduce a thermal conductivity between the cylinder block,
• wherein the cylinder block and the cylinder liner are bonded to each other from a top surface of the cylinder to a bottom surface of the cylinder, and
• wherein the film is made of a material that remains bonded to the second portion of the cylinder liner.