Automatic crankcase oil change and makeup system

The method of changing oil in the lubricating oil system of an internal combustion engine while the engine is running, which comprises the steps of:

• periodically removing a series of small increments of used lubricating oil from said system, and
• not later than said removing of each of said increments of used oil, delivering a small increment of fresh lubricating oil into said system which is volumetrically not substantially less than such increment of used oil;
• each of said increments of used oil being received in displacement means while it is being removed from said system and the corresponding said increment of fresh oil being substantially simultaneously delivered from said displacement means into said system;
• whereby the volume of oil in said system is not materially reduced by said removing of each of said increments of used oil.

The method of changing oil in the lubricating oil system of an internal combustion engine while the engine is running, said lubricating oil system comprising oil sump means containing a portion of the lubricating oil in said system, which comprises the steps of:

• periodically removing a series of small increments of used lubricating oil from said system, and
• not later than said removing of each of said increments of used oil, delivering a small increment of fresh lubricating oil into said system which is volumetrically not substantially less than such increment of used oil;
• whereby the volume of oil in said system is not materially reduced by said removing of each of said increments of used oil;
• said method comprising the further steps of:
• sensing the level of oil in said sump at least each time a said successive increment of used oil is removed from said system;
• if the oil level so sensed is not substantially below a predetermined satisfactory operating level when a said successive increment of used oil is removed, then delivering that removed increment of used oil to receptacle means;
• but if the oil level so sensed is substantially below said predetermined level when that increment of used oil is removed, then delivering that removed increment of used oil to said system, whereby the corresponding increment of fresh oil that is delivered to said system constitutes makeup oil.

A system for changing oil in the lubricating oil circuit of an internal combustion engine while the engine is running, which comprises:

• a source of fresh lubricating oil,
• used oil displacement means having an input connected to said circuit and an output, said used oil displacement means being operable to periodically remove a series of small increments of used lubricating oil from said circuit, and
• fresh oil displacement means having an input connected to said fresh oil source and an output connected to said circuit and being operable to periodically deliver a series of small increments of fresh oil to said circuit at substantially the same periodicity as said used oil displacement means removes used oil increments from said circuit,
• each said fresh oil increment being volumetrically not substantially less than a corresponding said used oil increment and being delivered to said circuit not later than said removal of such corresponding used oil increment, whereby the volume of oil in said circuit is not materially reduced by said removing of each of said used oil increments,
• said used oil displacement means and said fresh oil displacement means comprising hydraulic cylinder means having used oil chamber means therein which defines a said used oil increment and having fresh oil chamber means therein which defines a said fresh oil increment,
• said used oil input and output communicating with said used oil chamber means, and said fresh oil input and output communicating with said fresh oil chamber means.

The system of claim which further comprises receptacle means,

• normally closed second and third valve means,
• second fluid conduit means from said used oil chamber means through said used oil output to both of said second and third valve means,
• third fluid conduit means from said second valve means to said receptacle means,
• fourth fluid conduit means from said third valve means to said circuit,
• opening of said second valve means during said second phase of actuation causing such increment of used oil to be delivered through said second and third conduit means to said receptacle means, and
• alternative opening of said third valve means during said second phase of actuation causing such increment of used oil to be delivered through said second and fourth conduit means back into said circuit.