US 6,390,240 B1Granted

Method and device for lubricating a machine especially an internal combustion engine

AssigneeDaimlerChrysler AG

InventorsTimo Schmidt, Michael Wiesner, Martin Schulz

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Abstract

A device for lubricating a machine comprises at least one pump or arranged in the oil circuit as well as a first oil tank for keeping a reserve of a first oil and a second oil tank for keeping a reserve of a second oil and temporarily storing an oil mixture. Oil lines are also provided between the oil tanks and the lubricating points. Furthermore, there is an oil sump for collecting the oil or oil mixture downstream of the lubricating points. Oil lines are provided between the oil sump and the two oil tanks. At least one first switching device is arranged in the oil lines, for opening or blocking the oil lines. Between the second oil tank and the first oil tank there is an oil line, which can be controlled by a second switching device. This device has the effect of improving the lubrication and extending the oil intervals.

Claims21

Dependent claims

A method for lubricating an internal combustion engine, comprising the following steps:

in the cold state of the engine, a first oil of low viscosity is fed by means of an oil pump from a first oil tank to various lubricating points, is collected in an oil sump and is returned to the first oil tank,
during the supplying of the lubricating points with the first oil from the first oil tank, a second oil of higher viscosity is kept ready in a second oil tank,
after the warming up of the engine to a predetermined switching temperature, the oil circuit is switched over by a first temperature-controlled switching device in such a way that the second oil is fed from the second oil tank to the lubricating points, it being mixed with the residue of the first oil remaining in the engine to form an oil mixture, is collected in the oil sump and is returned to the second oil tank, so that after a transitional time, the oil in the second oil tank is replaced by the oil mixture and then the oil mixture is fed to the lubricating points,
after the engine has been shut down and has cooled down below a limit temperature, the oil mixture in the second oil tank is fractionated into the first oil and the second oil,
once fractionation has taken place, a connecting line between the second oil tank and the first oil tank is opened by means of a second switching device and the first oil located in the second oil tank is returned via the said connecting line into the first oil tank, the second oil remaining in the second oil tank.

2 more elements

A lubricating system for an internal combustion engine having a plurality of lubricating points, an oil supply circuit for supplying oil to said lubricating points, at least one oil pump arranged in said oil circuit for pumping said oil, a first oil tank for containing a reserve of a first oil having a low viscosity, a second oil tank for containing a reserve of a second oil having a higher viscosity than said first oil and for temporarily storing a mixture of said first and second oils, said oil circuit including oil supply lines extending from said first and second oil tanks to said lubricating points for supplying said low viscosity oil to said lubricating points upon starting said internal combustion engine and said higher viscosity oil from said second tank to said lubricating points upon warm-up of said engine, an oil sump for collecting the oil from said lubricating points, and oil return lines extending between said oil sump and said first and second oil tanks and including at least a first switching device for controlling the flow of said oil from said sump selectively through said first or said second tank, and a tank communication line extending between said first and second tanks and including a second switching device for controlling the return of said first oil from said second tank to said first tank after separation of said first and second oils in said second tank when the engine has been shut down.

Dependencies are inferred from the claim text.