Cummins Engine Company, Inc.

Timothy A Warlick

Lester L Peters

Julius P Perr

Jeffrey L Campbell

Michael E Lucas

Kuang-Wen T Wan

A fuel injector includes an injector housing having a plunger assembly disposed within a central axial bore and including a lower plunger, an intermediate plunger, and an upper plunger. The lower plunger reciprocates within the central bore to meter a variable quantity of fuel during downward portions of the reciprocating motion. A timing spring is wound around the upper portion of the lower plunger to bias the lower plunger upwardly. A timing chamber formed between the upper and intermediate plungers receives timing fluid to create a hydraulic link between the plungers. Timing fluid exits the timing chamber through a central passage, which may have a reduced area regulating orifice, formed through the intermediate plunger, which is ordinarily closed by a valve mechanism. The valve mechanism is acted upon in part by the timing spring. To improve the pressure regulation using a higher spring load and to accommodate a larger area drainage passage, a valve spring biases closed the passage. The force provided by the valve spring is predetermined to open the valve mechanism and drain timing fluid when the timing fluid pressure exceeds the maximum pressure during injection. After injection is completed, timing fluid exits from the timing chamber either through the central passage or through a spillport which is closable by the nonbeveled lower portion of the upper plunger.

High pressure unit fuel injector with timing chamber pressure control

A unit injector (200,300,400,500) of the cam actuated, open nozzle type is disclosed including an extremely compact injector body (202,302,402,502) having a minimum number of internal flow passages and a two piece injector plunger (222,308,310,412,506,510) arranged to provide pressure/time metering (all embodiments), scavenging fuel flow (all embodiments), hydraulic timing (all embodiments), fuel cut off (all embodiments), wear compensation in advance timing mode (all embodiments) and sharp cut off of fuel injection without high 'crush' loads and wear injection without high 'crush' loads and wear compensation in retard and advance modes (embodiment of FIG. 3). All embodiments of this invention are characterized by an injector body (202,302,402,502) having an exterior shape designed to form a fuel supply flow path and an isolated fuel drain flow path between the exterior surface of the injector body (202,302,402,502) and the interior surface of the recess in which the injector (200,300,400,500) is designed to be received. This arrangement allows a very simple pattern of passages (mostly radial passages) to be formed in the injector body.

Unit injector employing hydraulically controlled timing and fuel shut off

A unit injector (200, 300, 400, 500, 600) of the cam actuated, open nozzle type is disclosed including an extremely compact injector body (202, 302, 402, 502) having a minimum number of internal flow passages and a two piece injector plunger (222, 308, 310, 412, 506, 510, 606, 612) arranged to provide pressure/time metering (all embodiments), scavenging fuel flow (all embodiments), hydraulic timing (all embodiments), fuel cut off (embodiments of FIGS. 1, 3 and 4), wear compensation in advance timing mode (all embodiments) and sharp cut off of fuel injection without high 'crush' loads and wear compensation in retard and advance modes (embodiment of FIG. 3). All embodiments of this invention are characterized by an injector body (202, 302, 402, 502) having an exterior shape designed to form a fuel supply flow path and an isolated fuel drain flow path between the exterior surface of the injector body (202, 302, 402, 502) and the interior surface of the recess in which the injector (200, 300, 400, 500, 600) is designed to be received. This arrangement allows a very simple pattern of passages (mostly radial passages) to be formed in the injector body.

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Columbus, IN, United States of America

Timothy A Warlick