Methods and systems are provided for an oil gallery of a piston. In one example, a system for a piston comprising an internal oil gallery. The internal oil gallery comprises one or more of a funnel shaped inlet, a funnel shaped outlet, and a plurality of tongues extending along a circumference of the internal oil gallery.

Methods and systems are provided for an oil gallery of a piston. In one example, a system for a piston comprising an internal oil gallery. The internal oil gallery comprises one or more of a funnel shaped inlet, a funnel shaped outlet, and a plurality of tongues extending along a circumference of the internal oil gallery.

To provide a piston for an internal combustion engine configured to ensure a required amount of cooling oil to be effectively guided to portions that need to be cooled and to achieve a lightweight structure. A piston 3 comprises a piston crown portion 24 including a top portion 21 and a pair of pin boss portions each having a piston pin hole to allow insertion of a piston pin and configures to be cooled by a cooling oil injected from an oil jet apparatus having a nozzle toward a back surface 30a of the top portion 21. The top portion 21 comprises cooling voids 29a, 29b provided near at least one of the pin boss portions inside the top portion 21 and inlet openings 35a, 35b provided on the back surface 30a and configured to guide the oil injected from the nozzle toward the cooling voids 29a and 29b.

A cooling apparatus of a piston according to an exemplary embodiment of the present disclosure may include a piston configured to be formed with a cooling gallery, an inlet fluidly communicated with the cooling gallery, and an outlet fluidly communicated with the cooling gallery, therein, a first oil jet configured to inject cooling oil into the inlet, and a second oil jet configured to inject cooling oil into the outlet.

A cooling apparatus of a piston according to an exemplary embodiment of the present disclosure may include a piston configured to be formed with a cooling gallery, an inlet fluidly communicated with the cooling gallery, and an outlet fluidly communicated with the cooling gallery, therein, a first oil jet configured to inject cooling oil into the inlet, and a second oil jet configured to inject cooling oil into the outlet.

It is an object of the present invention to provide a novel internal-combustion engine piston which makes it possible to achieve both an improvement in thermal efficiency and a reduction in exhaust harmful components, and to suppress the occurrence of abnormal combustion such as knocking and pre-ignition. A cooling passage is formed in a piston, and on a top face of the piston are provided a first heat shielding layer composed of a material having a lower thermal conductivity and volumetric specific heat than those of a piston base material, and a second heat shielding layer composed of a material having a lower thermal conductivity and volumetric specific heat than those of the first heat shielding layer, wherein a first distance between the first heat shielding layer and the cooling passage is set to be less than a second distance between the second heat shielding layer and the cooling passage. A cooling loss can be reduced by the second heat shielding layer, and the vaporization of fuel adhering to the piston can be promoted by the first heat shielding layer to reduce exhaust gas harmful components. Since the first distance is less than the second distance, the temperature of the first heat shielding layer does not rise excessively, whereby the occurrence of knocking and pre-ignition can be suppressed.

It is an object of the present invention to provide a novel internal-combustion engine piston which makes it possible to achieve both an improvement in thermal efficiency and a reduction in exhaust harmful components, and to suppress the occurrence of abnormal combustion such as knocking and pre-ignition. A cooling passage is formed in a piston, and on a top face of the piston are provided a first heat shielding layer composed of a material having a lower thermal conductivity and volumetric specific heat than those of a piston base material, and a second heat shielding layer composed of a material having a lower thermal conductivity and volumetric specific heat than those of the first heat shielding layer, wherein a first distance between the first heat shielding layer and the cooling passage is set to be less than a second distance between the second heat shielding layer and the cooling passage. A cooling loss can be reduced by the second heat shielding layer, and the vaporization of fuel adhering to the piston can be promoted by the first heat shielding layer to reduce exhaust gas harmful components. Since the first distance is less than the second distance, the temperature of the first heat shielding layer does not rise excessively, whereby the occurrence of knocking and pre-ignition can be suppressed.

A cooling apparatus of a piston according to an exemplary embodiment of the present disclosure may include a piston configured to be formed with a cooling gallery, an inlet fluidly communicated with the cooling gallery, and an outlet fluidly communicated with the cooling gallery, therein, a first oil jet configured to inject cooling oil into the inlet, and a second oil jet configured to inject cooling oil into the outlet.

A cooling apparatus of a piston according to an exemplary embodiment of the present disclosure may include a piston configured to be formed with a cooling gallery, an inlet fluidly communicated with the cooling gallery, and an outlet fluidly communicated with the cooling gallery, therein, a first oil jet configured to inject cooling oil into the inlet, and a second oil jet configured to inject cooling oil into the outlet.

A piston of an internal combustion engine may include a piston shaft and a piston head. The piston head may be provided with a closed cooling channel with a cooling medium arranged therein. The piston shaft may have a spherically round cross-sectional shape, wherein a deviation from the roundness with respect to a piston diameter may be less than 0.5 per thousand.