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.

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 piston of an internal-combustion engine may include a piston head and a piston skirt, a cooling duct circulating in the piston head, a boss for receiving a piston pin, and a feed hopper for supplying cooling oil into the cooling duct. The feed hopper may be fastened to another component of the piston via a retaining lug by at least one of a material closure, a force closure, and a positive closure.

A piston of an internal-combustion engine may include a piston head and a piston skirt, a cooling duct circulating in the piston head, a boss for receiving a piston pin, and a feed hopper for supplying cooling oil into the cooling duct. The feed hopper may be fastened to another component of the piston via a retaining lug by at least one of a material closure, a force closure, and a positive closure.

A steel piston (10) for an internal combustion engine has a cooling channel and shaft surfaces (12, 14) with which the piston (10), in the installed state, abuts a cylinder bore or a cylinder liner on a pressure side and a counterpressure side, wherein one shaft surface (12) has a width which is 25-50% smaller than the other shaft surface (14).

A steel piston (10) for an internal combustion engine has a cooling channel and shaft surfaces (12, 14) with which the piston (10), in the installed state, abuts a cylinder bore or a cylinder liner on a pressure side and a counterpressure side, wherein one shaft surface (12) has a width which is 25-50% smaller than the other shaft surface (14).

A one-piece cast piston (10) for an internal combustion engine includes a cooling channel (12) and at least one rib (18) on the inner side of the piston opposite the recess base of a combustion bowl (14).

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 piston with an oil return channel may include a piston head, a piston skirt, and an oil return hole. The piston head may include a ring groove. The piston skirt may be connected to the piston head. The piston skirt may have a surface including a concave face window. A connection between the face window and the ring groove may form a residual ring bank. The oil return hole may be formed by milling on the residual ring bank. The oil return hole may connect the ring groove close to the piston skirt with the face window. A depth of the oil return hole may be greater than a depth of the ring groove.