Caterpillar Inc.

Scott C Brown

Martin Leo Willi

Eric W Ohlson

Jeffery T Fischer

Geoffrey D Ginzel

James B Maddock

Raymond G Evans

Shawn J Weck

A method for controlling and adjusting the delivery of liquid pilot fuel to each cylinder of a dual fuel engine during a dual fuel operating mode so as to both minimize the quantity of liquid pilot fuel being delivered to each individual cylinder while, at the same time, ensuring that such minimum quantity of liquid pilot fuel provides complete combustion performance within each such cylinder wherein certain cylinder performance parameters such as exhaust port temperature or cylinder pressure are evaluated on a per cylinder basis in order to determine cylinder performance. The present method establishes certain predetermined incremental changes in the selected cylinder performance parameters, which changes are indicative of poor or deteriorated combustion performance within any particular cylinder, and thereafter varies the amount of liquid pilot fuel delivered to such cylinder based upon an analysis and evaluation of changes occurring in the selected cylinder performance parameters. Although it is preferred that each cylinder be evaluated on an individual basis, it is recognized and anticipated that, in some applications, the present method may be used to control the delivery of liquid pilot fuel to two or more cylinders simultaneously.

Method for achieving minimum liquid pilot fuel delivery to each cylinder of a dual fuel engine while operating in a dual fuel mode

A method for controlling delivery of fuel to each cylinder of an engine by adjusting the appropriate fuel valve duration times to each such cylinder based upon a predetermined detonation level. By using the detonation level measurements from each individual cylinder as a controlling parameter, the delivery of fuel to that particular cylinder can be trimmed to achieve the predetermined detonation level. Balancing the detonation level for each such cylinder to a common detonation level likewise produces a substantially identical air/fuel ratio in each such cylinder. The detonation control loop can be initiated at predetermined intervals so as to continuously maintain a balanced air/fuel ratio to each cylinder in any particular engine.

Method for balancing the air/fuel ratio to each cylinder of an engine

A method for transitioning between a first operating mode of a dual fuel engine and a second operating mode of the dual fuel engine includes establishing a final liquid fuel amount desired to be delivered to the engine upon completion of the transition to the second operating mode. Delivery of liquid fuel to the engine is adjusted by a first amount and, correspondingly, delivery of gaseous fuel to the engine is adjusted by a second amount, where an energy content of the first amount of liquid fuel is substantially the same as an energy content of the second amount of gaseous fuel. A determination is made as to whether liquid fuel is being delivered to the engine in an amount which is substantially the same as the desired final liquid amount previously established. The fuel adjustment step and the determination step are repeated until a determination is made that liquid fuel is being delivered to the engine in an amount which is substantially the same as the desired final liquid fuel amount, at which point the transition is considered complete.

Method for a controlled transition between operating modes of a dual

In one embodiment of the present invention an apparatus for controlling one or more engines by synchronizing the functions of two or more electronic control modules includes a master electronic control module, one or more slave electronic control modules, and one or more data links for transferring data between the electronic control modules. Engine control and monitoring functions are divided between the master electronic control module and the slave electronic control modules. The present invention may be used to control and monitor dual fuel engines and engines that operate on one type of fuel. The master electronic control module may transition operation of the engine to the diesel fuel only mode in the event of a failure of any dual fuel mode specific components. The master ECM coordinates timing and speed of fuel injection to engine cylinders using input from an adjustable engine speed command device and a speed sensor connected to each engine. The loads driven by the engines may be allocated evenly or unevenly.

Apparatus for an engine control system

A method for adjusting a fuel control system of an internal combustion engine to account for variations in the energy content of a fuel delivered to the engine involves monitoring the O.sub.2 level of the engine exhaust gases. The fuel may be a gaseous fuel for example. The fuel control system utilizes a stored gaseous fuel energy content value (E.sub.G) to determine the necessary duration of a gaseous fuel admission valve control signal. The method includes sensing an actual engine exhaust gas O.sub.2 level and comparing the actual exhaust gas O.sub.2 level with a desired exhaust gas O.sub.2 level. The stored gaseous fuel energy content value (E.sub.G) is adjusted based upon the comparison. The desired exhaust gas O.sub.2 level may be determined as a function of one or more engine operating parameters which indicate a desired or expected air/fuel ratio, the level of O.sub.2 in the exhaust gases being an indicator of the air/fuel ratio.

Method for determining the energy content of a fuel delivered to an

A method of detecting leakage through a gaseous fuel admission valve of a dual fuel engine including at least one such gaseous fuel admission valve and a gaseous fuel shut off valve includes determining a liquid fuel rate when the engine is operating in a liquid fuel mode and the gaseous fuel shut off valve is closed. The gaseous fuel shut off valve is thereafter opened while the engine is operating in the liquid fuel mode. A liquid fuel rate is determined after the gaseous fuel shut off valve is opened and the liquid fuel rate determined before opening of the gaseous fuel shut off valve is compared with the liquid fuel rate determined after opening of the gaseous fuel shut off valve. A detonation level within the engine cylinder may also be checked to determine if such detonation level exceeds a predetermined level indicative of gaseous fuel leakage. The detonation level check may also be utilized in a spark-ignited engine.

Method and apparatus for detecting gaseous fuel leakage through a

A method for responding to detection of an open fault condition in a gaseous fuel admission valve for providing a flow of gaseous fuel to an affected combustion cylinder of an engine, the engine including at least one other gaseous fuel admission valve for providing a flow of gaseous fuel to at least one other combustion cylinder, a gaseous fuel shut off valve for controlling gaseous fuel flow from a source of gaseous fuel to a gaseous fuel manifold in communication with the gaseous fuel admission valve, and apparatus for causing ignition of a mixture of the gaseous fuel and air in each combustion cylinder. The present method involves the steps of closing the gaseous fuel shut off valve; disabling the ignition of the mixture of gaseous fuel and air in the affected combustion cylinder; and continuing operation of the at least one other gaseous fuel admission valve to allow flow of remaining gaseous fuel in the gaseous fuel manifold through the at least one other gaseous fuel admission valve into the at least one other combustion cylinder of the engine where the gaseous fuel can be combusted. In the instance of an engine operating in a dual fuel mode, at a suitable point, operation can be shifted to a liquid fuel mode. In the instance of an engine that operates solely on gaseous fuel, once the gaseous fuel remaining in the gaseous fuel manifold is exhausted, the engine will come to rest.

Method for responding to detection of an open fault condition in a

A method for controlling delivery of fuel to each cylinder of an engine by adjusting the appropriate fuel valve duration times to each such cylinder based upon either a desired cylinder exhaust port temperature, or a predetermined detonation level. By using the exhaust port temperature measurements and/or detonation level measurements from each individual cylinder as a controlling parameter, the delivery of fuel to that particular cylinder can be trimmed to achieve the desired exhaust port temperature and/or predetermined detonation level. Balancing the exhaust port temperature and/or detonation level for each such cylinder to a common desired exhaust port temperature and/or detonation level likewise produces a substantially identical air/fuel ratio in each such cylinder. Both the exhaust port temperature control loop and the detonation control loop can be initiated at predetermined intervals so as to continuously maintain a balanced air/fuel ratio to each cylinder in any particular engine and, in certain situations, both control loops can operate simultaneously with respect to any particular cylinder.

A method for adjusting a fuel control system of an engine capable of operating in both a first mode during which only a first fuel is delivered to the engine and a second mode during which both the first fuel and a second fuel are delivered to the engine includes operating the engine in the first mode during which a governor output value (X.sub.M1) is established and stored in memory. The engine is then operated in the second mode during which a governor output value (X.sub.M2) is established. The governor output value (X.sub.M2) is compared with the stored governor output value (X.sub.M1) and a stored second fuel energy content value is adjusted based upon the comparison. The actual energy content of the second fuel can also be directly calculated.

A method for delivering liquid fuel and gaseous fuel to a dual fuel engine operating in a dual fuel mode includes establishing a governor output value indicative of a total fuel energy rate desired to be delivered to the engine to maintain a desired engine speed. A first value indicative of a liquid pilot fuel energy rate desired to be delivered to the engine and a second value indicative of a gaseous fuel energy rate desired to be delivered to the engine are each determined such that the sum of the desired liquid pilot fuel energy rate and the desired gaseous fuel energy rate is substantially equal to the desired total fuel energy. A stored gaseous fuel energy content can be updated to assure continued accuracy of the fuel control system of the dual fuel engine.

Method for enabling a substantially constant total fuel energy rate

A fuel pressure relief system for a dual fuel engine including at least one gaseous fuel admission valve positioned between a gaseous fuel inlet region and an air intake region is provided. The system includes a first pressure sensor positioned in the gaseous fuel inlet region and a second pressure sensor positioned in the air intake region. An electronic controller is connected to the first pressure sensor and the second pressure sensor. A gaseous fuel vent path extends between the gaseous fuel inlet region and a portion of an air intake path of the engine. A vent valve is positioned along the gaseous fuel vent path and is connected to the electronic controller for control thereby. When the differential pressure across the gaseous fuel admission valve exceeds a predetermined level the fuel vent valve is opened to relieve the pressure.

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Peoria, IL, United States of America

Scott C Brown