Expansible chamber devices – Passage in cylinder for application of separate fluid to...
Reexamination Certificate
1997-11-26
2001-01-23
Thorpe, Timothy S. (Department: 3746)
Expansible chamber devices
Passage in cylinder for application of separate fluid to...
C092S087000
Reexamination Certificate
active
06176171
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to lubricated pumps, and more particularly to heavy diesel fuel injection pumps having precipitate inhibiting features.
BACKGROUND ART
In one class of liquid pumps, a pump body defines a plunger bore within which a plunger reciprocates with each pumping stroke of the device. In order to prevent the plunger from sticking or seizing, a lubricant, such as lubricating oil, must often be employed. In some cases, such as heavy diesel fuel injection pumps, the lubricant itself can sometimes be a source of plungers 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.
The present invention is directed to overcoming these and other problems associated with the formation of precipitates in lubricated pumps, especially heavy diesel fuel injection pumps.
DISCLOSURE OF THE INVENTION
In one embodiment, a pump with precipitate inhibiting features includes a pump body that defines a flushing fluid inlet and a flushing fluid outlet that open into a plunger bore. A plunger is positioned in the plunger bore and moveable between a retracted position and an advanced position. The plunger has a first end separated from a second end by a side surface. A portion of the plunger's side surface and the plunger bore define a flush connection passage that connects the flushing inlet to the flushing fluid outlet over a portion of the plunger's movement between its retracted position and its advanced position.
In another embodiment of the present invention, a fuel injection pump with precipitate inhibiting features includes a pump body that defines a flushing fluid inlet and a flushing fluid outlet that open into a plunger bore. A plunger is positioned in the plunger bore and moveable between a retracted position and an advanced position. The plunger has a first end separated from a second end by a side surface. A portion of the plunger's side surface and the plunger bore define a flush connection passage that connects the flushing fluid inlet to the flushing fluid outlet over part of the plunger's movement between its retracted position and its advanced position. A different portion of the plunger's side surface blocks the flushing fluid inlet from the flushing fluid outlet over a different part of the plunger's movement between its retracted position and its advanced position. A portion of the plunger bore and a portion of the plunger adjacent its first end define a fuel pressurization chamber. The first end of the plunger is attached to a tappet.
In still another embodiment, a fuel injection pump with precipitate inhibiting features includes a pump body that defines a flushing fluid inlet and a flushing fluid outlet that open into a plunger bore. The plunger is positioned in the plunger bore and moveable between a retracted position and an advanced position. The plunger has a first end, which is exposed to lubricating oil, that is separated from a second end, which is exposed to heavy diesel fuel, by a side surface. A portion of the side surface and the plunger bore define a flush connection passage that connects the flushing fluid inlet to the flushing fluid outlet over part of the plunger's movement between its retracted position and its advanced position. A different portion of the plunger's side surface blocks the flushing fluid inlet from the flushing fluid outlet over a different part of the plunger's movement between its retracted position and its advanced position. The flushing fluid inlet is connected to a source of flushing fluid that is different from lubricating oil and heavy diesel fuel.
REFERENCES:
patent: 4826081 (1989-05-01), Zwick
patent: 4963077 (1990-10-01), Besic
patent: 5337651 (1994-08-01), Gardiner
patent: 5431957 (1995-07-01), Gardiner
patent: 2123492A (1984-02-01), None
patent: 641153 (1979-08-01), None
US Patent Appl No. 08/762,504, Method and Apparatus For Injecting Fuel Using Control Fluid to Control the Injection's Pressure and Time US Pat 5826501.
Patent Abstracts of Japan, vol. 009, No. 098 (M-375), Apr. 27, 1985 & JP 59 221459 A (Mitsubishi Jukogyo KK), Dec. 13, 1984.
Caterpillar Inc.
Gartenberg Ehud
McNeil Michael B.
Thorpe Timothy S.
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