System, method, and apparatus for injecting a gas in a diesel engine

A method of supplementing a primary fuel with a secondary fuel in an engine, the method comprising:

• calculating a maximum amount of secondary fuel that can be injected into a cylinder of the engine based upon a secondary fuel thermal energy content per unit volume, a number of secondary fuel injectors interfaced to an intake valve port of the cylinder, a flow rate of each of the secondary fuel injectors, and a time window that is proportional to the rotational speed of a crankshaft of the engine;
• calculating a maximum amount of heat energy provided by the maximum amount of the secondary fuel;
• calculating a total amount of heat energy needed by multiplying a primary fuel injection pulse width from a previous primary fuel injection cycle of the cylinder by an amount of heat energy per time period that would be delivered to the engine given the primary fuel and the primary fuel injection pulse width;
• determining a replacement ratio by comparing the maximum amount of heat energy provided by the maximum amount of secondary fuel with the total amount of heat energy needed;
• if the replacement ratio is greater than a predetermined maximum replacement ratio, setting the replacement ratio to the predetermined maximum replacement ratio;
• after an exhaust valve of the cylinder closes, injecting an amount of the secondary fuel into the intake valve port of the cylinder determined by the replacement ratio;
• and
• when a next primary fuel injection pulse is received, relaying a portion of the primary fuel injection pulse width to a primary fuel injector of the cylinder based upon the replacement ratio.

A secondary fuel injection system comprising:

• a source of secondary fuel;
• a secondary fuel injector fluidly coupled to the source of secondary fuel, the secondary fuel injector electrically controlled to inject an amount of the secondary fuel into an intake valve port of a cylinder of an engine;
• means for determining a rotational speed of a crankshaft of the engine, the engine having an engine control module, an injection signal that was connected between the engine control module and a primary fuel injector of the cylinder is intercepted and routed to a processor;
• the processor interfaced to the means for determining the rotational speed of the engine, the processor receiving the rotational speed of the crankshaft;
• software running on the processor calculating an amount of time available for injection of the secondary fuel into the intake valve port of a respective cylinder;
• the software calculating a first amount of heat energy required by the engine for a next cycle by multiplying a width of a primary fuel injection pulse received on the injection signal by an amount of heat energy per time period based upon a specification of the engine;
• the software calculating a second amount of heat energy that is to be provided to the engine by injection of the secondary fuel;
• the software running on the processor electrically controlling the secondary fuel injector to open after an respective exhaust valve of the engine closes for a period of time required to provide the second amount of heat energy from the secondary fuel;
• and
• the software running on the processor providing an injection pulse to the primary fuel injector responsive to receiving a subsequent primary fuel injection pulse from the engine control module, a width of the injection pulse is timed to provide an amount of primary fuel having a heat energy that is equivalent to the first amount of heat energy minus the second amount of heat energy.