Caterpillar Inc.

Michael R Huffman

Dana Ray Coldren

Stephen Robert Lewis

Glen F Forck

Mingchun Dong

Matthew Bredesen

An electronically controlled fuel injector includes a reduced part count and complexity over similar fuel injectors without a substantial reduction in performance capabilities. This is accomplished by using a one-piece needle that is hydraulically balanced and biased toward a closed position with a spring positioned in the needle control chamber. Although subtle, this injector has some ability to control the fuel pressure when the needle valve is opening and closing by adjusting a relative timing of a pressure control valve opening relative to a needle control chamber, using separate electrical actuators. The invention is particularly applicable to fuel injectors that cycle through high and low pressure states during and between injection events, respectively. Cam actuated fuel injectors being particularly well suited.

Electronic unit injector with pressure assisted needle control

A fuel injection system includes a fuel pressurizer that may be cam actuated. The fuel injection system also includes an electronically controlled spill valve and an electronically controlled needle control valve. The energization of the electronically controlled spill valve closes a fuel pressurization chamber to a drain passage to allow fuel pressure in the fuel injector to build to injection levels. The electronically controlled needle control valve controls whether high or low fuel pressure is applied to a closing hydraulic surface associated with a direct control needle valve. The fuel injection system includes a hydraulic circuitry that allows for fuel injection to occur by either maintaining the electronically controlled needle control valve in a de-energized state, or by de-energizing the same, after fuel pressure within the fuel injector has built to injection levels. With a de-energize to inject hydraulic circuitry associated with the direct control needle valve, the fuel injection system can prevent overpressurization in the event of electrical failure in the needle control electronic circuitry. This also provides a fuel engine with a limp home capability in the case of such an electronic problem. In addition, the fuel injection system can have reduced overall power requirements that can lead to downsizing and other cost saving advantages.

Mechanically actuated, electronically controlled fuel injection system

An engine is provided comprising an engine housing defining at housing and has a different portion associated with each engine cylinder. Each different portion of the engine auxiliary system has a first electrical actuator coupled to a first valve and a second electrical actuator coupled to a second valve which are wired in series. For example, a fuel injection system is provided with a first electrical actuator operably coupled to a fuel pressurizer and a second electrical actuator operably coupled to a direct control needle valve. The electrical actuators are wired in series on an electrical circuit. A method of controlling a portion of the engine auxiliary system is also provided which consists of actuating a first electrical actuator with a relatively low current and actuating a second electrical actuator with a relatively high current.

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Pontiac, IL, United States of America

Michael R Huffman