Piston for an internal combustion engine

Abstract

A cooling structure for an internal combustion engine piston is provided. The piston includes an oil cooling channel integrated in the piston. The oil cooling channel has a bottom surface facing towards a top surface of the piston and a top surface facing away from the top surface of the piston. The oil cooling channel is provided with an oil inlet and an oil outlet which are laterally separated from each other. The bottom surface and / or the top surface of the oil cooling channel is slanted relative to a central axis of a wrist pin opening provided in said piston.

Description

BACKGROUND AND SUMMARY[0001]The present invention relates to a cooling structure for an internal combustion engine piston.[0002]Cooled pistons having an oil inlet are known from example U.S. Pat. No. 3,221,718 and DE 3733964. The oil inlets used as catch funnels for cooling oil that is dispensed from an oil spraying nozzle connected with the engine housing have inners walls that are configured to be funnel shaped, cylindrical, oval or in the form of a venture jet. In order to achieve better distribution, in the cooling duct, of the oil captured in this manner, additional dividers are inserted into the wall of the cooling duct, which lie opposite the exit surface of the oil inlet.[0003]Using such shaping structures, the result supposed to be achieved is that the oil stream that widens from the oil spraying nozzle is captured and passed to the cooling duct. These structures demonstrates defects in achieving a continuous oil fill level of the cooling duct, due to disadvanatageous flow ...

AI Technical Summary

Benefits of technology

[0007]An advantage of this aspect is that the oil flow can be better controlled resulting in improved cooling efficiency.

[0008]Another advantage is that oil may be forced from the oil inlet to the oil outlet in almost a complete rotation of a crank axle in said internal combustion engine.

[0014]An advantage of this embodiment is that the oil level can be better controlled.

[0016]An advantage of this embodiment is that the oil circulation can be better controlled.

Problems solved by technology

These structures demonstrates defects in achieving a continuous oil fill level of the cooling duct, due to disadvanatageous flow and friction conditions during entry of the cooling oil into the inlet.

However, in U.S. Pat. No.7,051,684 there is still a problem with the fill level in the oil cooling duct and the amount of oil circulating in said oil cooling duct in said piston for achieve sufficient cooling of the piston.

Especially, there is a problem if the oil level in the oil duct in said piston becomes to small.

The small oil level may cause too much air to be mixed with the oil when the engine rev is in a higher range.

Air is a very bad thermal conductor, which decreases the cooling efficiency dramatically.

Another problem with the design of U.S. Pat. No. 7,051,684 is that the circulation of oil in the oil cooling duct is too low.

A too low circulation of oil in the oil cooling duct will further decrease the cooling efficiency.

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