COOLING DUCT FOR A PISTON OF A COMBUSTION ENGINE

Abstract

Disclosed is a cooling duct (6) for a piston (1) of a combustion engine. The cooling duct (6) has an annular shape and comprises two openings (7, 8) which are arranged next to each other and are alternately used as inlets as well as at least one outlet (15, 16) on the side of the cooling duct (6) located radially opposite the openings (7, 8). In order to allow the oil to more easily flow through the cooling duct (6) and thus the piston (1) to be better cooled, the cooling duct (6) has two outlets (15, 16) that are arranged next to each other as well as a reduced cross-section (17) which lies between the two outlets and acts as a throttle.

Description

The invention relates to a cooling channel of a piston for an internal combustion engine, in accordance with the preamble of the claim.

A cooling channel for a piston of an internal combustion engine is known from the European patent EP 1 063 409 B1, which channel has two openings that are disposed next to one another and are intended to be alternately used as inflow openings, and an outflow opening disposed on the side of the cooling channel that lies radially opposite these openings. It is disadvantageous, in this connection, that the oil introduced into the cooling channel flows through the cooling channel at a very high flow velocity, whereby only a small part of the oil flows out by way of the outflow opening, and the rest continues to flow, at a high flow velocity, to the second opening, alternately used as an inflow opening, and flows out of the cooling channel by way of this opening. If the oil outflow is stopped by the oil jet that impacts this second opening, because of a changed position of the piston, so that now oil can be introduced into the cooling channel by way of this opening, eddies occur in the oil, which hinder the oil flow in the channel and thus cause the cooling effect of the oil to deteriorate.

It is the task of the invention to avoid this disadvantage of the state of the art. This task is accomplished with the characteristics standing in the characterizing part of the claim.

The invention will be described in the following, using the drawing. This shows the cooling channel according to the invention, disposed in a piston for an internal combustion engine.

In the FIGURE, a piston 1 for an internal combustion engine is shown, having a ring belt 2, a piston crown 3, a piston skirt 4 that follows the ring belt 2 on the side facing away from the piston crown, and a pin bore 5 for a piston pin not shown in the FIGURE.

A ring-shaped cooling channel 6 is disposed close to the piston crown 3 of the piston 1, radially on the outside, which channel has two openings 7 and 8 on one side, which openings are connected with the ring-shaped part of the cooling channel 6 by way of a channel bend 9 and 10 in the shape of a quarter circle, in each instance, and face in the direction facing away from the piston crown. The openings 7 and 8 alternately serve as inflow openings or as outflow openings for oil 12 sprayed in the direction of the openings 7 and 8 by an oil nozzle 11.

In the FIGURE, the piston 1 is shown in a position that corresponds to the upper dead center of the piston 1. In this connection, the oil jet 12, which is directed at a slant with reference to the piston axis 13, impacts the opening 8, which therefore functions as an inflow opening. If the piston 1 moves downward, in the direction of the arrow 14, within the scope of the combustion or intake stroke, the opening 7 is impacted by the oil jet 12 starting from a specific piston position, so that then this opening 7 functions as an inflow opening for the oil 12.

On the side that lies radially opposite the openings 7 and 8, the cooling channel 6 has two outflow openings 15 and 16 that face in the direction facing away from the piston crown. Between the outflow openings 15 and 16, the cooling channel 6 has a cross-section narrowing 17 that acts as a throttle.

The throttle 17 brings about the result, for one thing, that part of the oil 12 sprayed into the opening 8 in the position of the piston 1 shown in the FIGURE is passed out of the outflow opening 16, and, for another, that the flow of the oil that continues to flow through the left half of the cooling channel 6 is slowed down, which has the effect that no eddies that would hinder the oil inflow by way of the opening 7, into the left half of the cooling channel 6, form in the oil in the left half of the cooling channel 6, when the piston 1 moves downward in the direction of the arrow 14, whereby the opening 7 gets into the jet path of the oil 12, in order to then function as an inflow opening. In this connection, oil then flows through the left half of the cooling channel 6 by way of the opening 7, and part of this oil flows out of the outflow opening 15 because of the throttle 17, and the rest continues to flow through the right half of the cooling channel 6, at a slower velocity, because of the throttle 17, in order to flow out of the opening 8. In this way, a rapid change in the oil flow direction in the cooling channel 6 and thus improved cooling of the piston 1 are achieved.

REFERENCE SYMBOL LIST

• 1 piston
• 2 ring belt
• 3 piston crown
• 4 piston skirt
• 5 pin bore
• 6 cooling channel
• 7, 8 opening
• 9, 10 channel bend
• 11 oil nozzle
• 12 oil, oil jet
• 13 piston axis
• 14 arrow
• 15, 16 outflow opening
• 17 cross-section narrowing, throttle

Claims

1. Cooling channel (6) of a piston (1) for an internal combustion engine, having a piston crown (3) and a ring belt (2), wherein the cooling channel (6) is configured in ring shape and is disposed close to the piston crown (3) of the piston (1), radially on the outside, close to its ring belt (2), and has two openings (7, 8) that are disposed next to one another and are intended to be alternately used as inflow openings, and at least one outflow opening (15, 16) disposed on the side of the cooling channel (6) that lies radially opposite the openings (7, 8), wherein the cooling channel (6) has two outflow openings (15, 16) disposed next to one another, and a cross-section narrowing (17) disposed between them, which acts as a throttle.