Walbro Corporation

John D Zmierski

Kirk D Doane

A fuel pressure regulation system for an internal combustion engine to regulate fuel pressure using a two-state pressure switch. In addition to the pressure switch, the system includes a control circuit, a current sensor, and a fuel pressure control device such as a fuel pump. The control circuit uses the pressure switch to sense whether the downstream fuel pressure is above or below a desired reference pressure. When below the reference pressure, the control circuit drives the fuel pump at full on to increase the fuel line pressure to the reference pressure. Once the fuel pressure rises and increases to or past the reference pressure, the pressure switch changes state, at which point the current sensor is used to sample and record the magnitude of the electric current supplied to the fuel pump at the moment the switch state changes. As long as the fuel line pressure is above the reference pressure, this stored value is used as a reference value in conjunction with the current measurement reading from the current sensor to provide closed loop control of the fuel pump operating current.

Fuel pressure regulation system

A fuel pressure regulation system for use in a fuel pump system in which atomizing air is injected into the fuel delivered to the injector. The system includes both an air rail and a fuel rail and is operable to maintain the fuel pressure within the system at a consistent pressure above the air rail pressure. The system also includes a first pressure sensor, a second pressure sensor, a control circuit, and a fuel pressure pump or other fuel control device. The first and second pressure sensors are differential pressure sensors which measure the air and fuel pressure, respectively, convert those measurements into first and second electronic signals, and send those signals to the control circuit. The control circuit is an electronic circuit that includes a first stage, a second stage, and an output stage and provides the fuel pump with closed loop control based on the first and second signals. Preferably, the closed loop control is achieved using both proportional and integral control with the output being in the form of a pulse-width modulated signal. The fuel pump is in fluid communication with the fuel rail and adjusts the fluid pressure within the fuel rail according to the pulse-width insulated signal sent by the control circuit.

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Cass City, MI, United States of America

John D Zmierski