Heavy diesel fuel refers generally to the material that is left over after crude oil has been distilled. Heavy diesel fuel typically has viscosity somewhere on the order of road tar at ambient temperatures, and must normally be heated to temperatures in excess of 400.degree. Fahrenheit in order to make the same sufficiently flowable through a fuel injection pump. Due in part to the extremely high viscosity of heavy diesel fuel, the current state of the art in relatively large diesel engines continues to be cam actuated fuel injection pumps. In order to prevent the plunger from sticking or seizing, a lubricant, such as lubricating oil, must often be employed. In some cases, the lubricant itself can be a source of plunger sticking and seizures due to the formation of precipitates where the lubricating oil comes in contact with the heavy diesel fuel. One such precipitate includes the build-up of calcium carbonate in a plunger bore where heavy diesel fuel has migrated up the side of the plunger into contact with the lubricating oil.
Because there is often a relatively tight clearance between the reciprocating plunger and its bore, only a small amount of calcium carbonate build-up is necessary to cause the plunger to seize. Because of this problem, heavy diesel fuel injection pumps are periodically removed, disassembled, and cleaned in order to remove any calcium carbonate build-up. Depending upon what constituent chemicals are present in both the lubricating oil and the heavy diesel fuel, plunger seizures can occur in literally a matter of hours when calcium carbonate build-ups are high. More often, heavy diesel fuel injectors must typically be disassembled and cleaned about every one thousand hours of operation.
The present invention is directed to these and other problems associated with precipitate build-up in heavy diesel fuel injection pumps.
USPTO Backgrounds
USPTO Backgrounds