| US 7,584,747 B1 | ||
| Cam assisted common rail fuel system and engine using same | ||
| Daniel R. Ibrahim, Metamora, Ill. (US); and Stephen R. Lewis, Chillicothe, Ill. (US) | ||
| Assigned to Caterpillar Inc., Peoria, Ill. (US) | ||
| Filed on Mar. 26, 2008, as Appl. No. 12/79,292. | ||
| Int. Cl. F02M 69/46 (2006.01); F02M 69/50 (2006.01) | ||
| U.S. Cl. 123—456 [123/478] | 18 Claims |

| 1. A fuel system for an internal combustion engine comprising:
a plurality of nozzle groups, each of the nozzle groups having a nozzle body with a fuel inlet and at least one nozzle outlet,
a control passage, a nozzle supply passage and a drain, each of the nozzle groups further including a needle check movable
between a first check position blocking the at least one nozzle outlet from the nozzle supply passage and a second check position
where the at least one nozzle outlet is open to the nozzle supply passage, and each needle check further having a closing
hydraulic surface exposed to a fluid pressure of the corresponding control passage;
a common rail fluidly connecting with the fuel inlet of each of the nozzle groups and configured to supply a pressurized fuel
to the nozzle supply passage of each of the nozzle groups at a first pressure;
a plurality of pump groups each configured to supply a pressurized fuel to the nozzle supply passage of one of the nozzle
groups at a second, higher pressure, each pump group including a mechanically actuated pressure intensifier having a tappet;
each of the nozzle groups further including an electrically actuated needle control valve configured to control the needle
check and being movable between a first needle control valve position blocking the control passage from the drain, and a second
needle control valve position at which the control passage is open to the drain; and
each of the pump groups further including an electrically actuated pump valve comprising a spill valve movable between a first
pump valve position at which fuel is displaced from the pump group to a low pressure space and a second pump valve position
at which fuel is displaced from the pump group to the nozzle supply passage of the corresponding nozzle group; and
the fuel system further including a plurality of check valves each being positioned fluidly between one of the plurality of
pump groups and the nozzle supply passage of one of the plurality of nozzle groups and blocking fluid flow from the common
rail to the corresponding pump group.
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