Cummins Engine Company, Inc.

Bruce E Varney

Daniel K Hickey

Daniel K Vetters

Tibor Kiss

A unit fuel injector is provided which includes a threadless injector body attaching device for attaching an upper body section of the fuel injector to a lower body section while avoiding imparting a transverse load to the upper body section thereby minimizing bore distortion, plunger wear and the likelihood of injector failure. The threadless injector body attaching device includes a groove formed in the lower end of the upper body section and one or more apertures extending through the lower body section for positioning adjacent the groove. Also, one or more pins are provided for insertion into a respective aperture and connection to the lower body section. The groove and opposing aperture or apertures are sized to create a slip fit to avoid a contact force between the pin or pins and the upper body section. Upon assembly, the pin, aperture and groove create a relatively loose connection between the upper body section and the lower body section without transverse loads while utilizing the clamping load imparted by an injector mounting clamp to apply the necessary sealing load to the injector body to create a fluid seal between the upper and lower body sections.

Pinned injector assembly

An improved unit fuel injector is provided which effectively and precisely controls the timing of fuel injection by avoiding outside influences acting on a timing plunger. The unit fuel injector includes a timing plunger positioned between upper and lower plungers, a timing chamber positioned between the timing plunger and upper plunger and a spring chamber positioned between the timing plunger and a metering chamber for containing one or more springs for biasing the plungers. A spring chamber drain valve device is provided for directing fuel in the spring chamber to a low pressure drain while isolating the spring chamber from the low pressure drain system thereby preventing pressure variations in the drain system from entering the spring chamber and acting on the timing plunger. In addition, a scavenge circuit is provided to direct a scavenging flow of fuel and combustion gas from the injector directly to the low pressure drain without communication with the spring chamber. Consequently, pressure variations in the spring chamber are minimized thereby reducing the variations in biasing force on the timing plunger 38 to permit precise control of the timing fluid metering into the timing chamber by simply varying the timing fluid pressure.

Fuel injector with isolated spring chamber

A top stop assembly for a fuel injector is provided which includes a top stop housing having a threadless injector engaging portion positioned at one end of the housing for threadlessly engaging the outer diameter portion of an injector barrel to minimize inward bore distortion. The top stop is preferably formed integrally on the top stop housing body to create a predetermined axial length of the housing which defines a predetermined outer limit of a retraction stroke of an injector plunger assembly, i.e. a top stop position. The top stop position is set by selecting a top stop housing having a predetermined axial length corresponding to the desired top stop position thereby reducing costs and avoiding loosening problems associated with multi-part top stop assemblies.

Growing community of inventors

Columbus, IN, United States of America

Bruce E Varney