Importance

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Abstract

A lube oil and fuel blending system, pumping device and method are provided which effectively, inexpensively and controllably removes used lube oil from an engine and delivers the lube oil to the fuel system for consumption within the engine. The lube oil and fuel blending system includes a fuel pumping device or injector containing a bore and a plunger reciprocally mounted in the bore for movement through a retraction stroke and an advancement stroke, each having a predetermined stroke length. A fuel drain circuit communicates with the bore at a drain location spaced a predetermined seal length axially along the bore from an outer opening of the bore through which the plunger extends. The predetermined seal length is specifically designed less than the predetermined stroke length to cause lube oil on the outer portion of the plunger to be delivered by the plunger to the fuel drain circuit at the drain location. Fuel leakage through the fuel drain circuit washes the lube oil from the plunger thereby blending the lube oil and fuel and delivering the blend to the fuel supply system via a return line. A variable restriction valve may be provided in the return line to control the leakage flow. Therefore, the predetermined seal length can be chosen relative to the stroke to achieve a desired leakage rate. In another embodiment, an undercut may be used to increase the used lube oil leakage rate.

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First Claim