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AssigneeDaimler-Benz Aktiengesellschaft
InventorsViktor Pfeffer, Friedrich Wirbeleit
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The invention relates to a piston with variable compression height, particularly for internal-combustion engines, that consists of an interior piston part to which a connecting rod is coupled, and an exterior piston part that is slidably held at said interior piston part. In this case, the exterior piston, via two control chambers that are supplied with oil from the lubricating oil circuit, supports itself by adherence at the interior piston part, said control chambers being connected by a hydraulic system. In order to, in the process, keep the pressure in the oil feed to one control chamber approximately constant over the whole rotational speed range of the internal-combustion engine, the control chamber is connected to the lubricating oil circuit by means of a non-rotating control oil groove in the connecting rod bearing only in an indicated crank angle range, and/or the oil-carrying grooves and bores in the piston and in the connecting rod are coordinated with one another with respect to their cross-sections.
An arrangement for the control of the oil feed to a control chamber of a piston with variable compression height, particularly for internal-combustion engines, which control chamber is arranged between an interior piston part and an exterior piston part that is slidably guided at it, and which control chamber is connected to the lubricating oil circuit of the internal-combustion engine, via an oil bore arranged in said interior piston part, into the course of which a check valve is inserted that opens in the direction of said control chamber, and which oil bore leads out into an oil groove in a connecting rod small end bush of the connecting rod coupled to said interior piston part, as well as via a longitudinal oil bore leading from the oil groove through the connecting rod shaft to a control oil groove in the connecting rod bearing, and via a transverse bore extending in the crank pin between the control oil groove and a main oil bore, wherein the control oil groove extends only over a part of the bearing circumference in the connecting rod bearing and in the range between the last third of the outward motion of the piston to the last third of the inward motion of the piston, overlaps with the transverse bore.
An arrangement for the control of the oil feed to a control chamber of a piston with variable compression height, particularly for internal-combustion engines, which control chamber is arranged between an interior piston part and an exterior piston part that is slidably guided at it, and which control chamber is connected to the lubricating oil circuit of the internal-combustion engine, via an oil bore arranged in said interior piston part, into the course of which a check valve is inserted that opens in the direction of said control chamber, and which oil bore leads out into an oil groove in a connecting rod small end bush of the connecting rod coupled to said interior piston part, as well as via a longitudinal oil bore leading from the oil groove through the connecting rod shaft to a control oil groove in the connecting rod bearing, and via a transverse bore extending in the crank pin between the control oil groove and a main oil bore, wherein the cross-sectional area of the check valve determining the passage within the oil bore 16 in each case is larger than that of the control oil groove in the connecting rod bearing and the oil groove in the connecting rod bushing, and the cross-sectional area of the longitudinal bore is larger than that of the control oil groove in the connecting rod bearing.
A variable compression height piston construction comprising:
Dependencies are inferred from the claim text.