0432719 JOHNSON HOUSING & COVER ASSY.

Illustration 1 g02192355The fuel supply circuit is a conventional design for engines that use fuel injectors. The fuel supply circuit uses a fuel transfer pump to deliver fuel from the fuel tank to the electronic fuel injectors. The transfer pump is a fixed displacement gear pump.The fuel flows then through a fuel filter before entering the fuel supply manifold. A fuel priming pump is on the fuel filter base to fill the system. The system must be primed after the filter changes. The system must be primed after draining the fuel supply and return manifolds, when the fuel injectors are replaced.The fuel flows continuously from the fuel supply manifold through the fuel injectors. The fuel flows when either the supply or the fill port in the injector is not closed by the injector body assembly plunger. The fuel that is not injected into the cylinder is returned to the tank through the fuel return manifold.A pressure regulating valve is at the end of the fuel return manifold. The pressure regulating valve controls the entire fuel system pressure. The regulation provides proper filling of the fuel injectors.The electronically controlled mechanically actuated fuel injector system provides total electronic control of injection timing. The injection timing is varied to optimize the engines performance.The timing ring is part of the rear gear group. A signal is generated by the engine speed/timing sensor. This information is for detection of crankshaft position and for engine speed. Other information and these data allow the Electronic Control Module (ECM) to send a signal to the injector solenoids. The fuel injector solenoid is energized to begin fuel injection. The fuel injector solenoid is de-energized to end fuel injection. Refer to Systems Operation, "Fuel Injector".Gas System
The percentage of gas blending that is allowed is based on the load of the engine. The actual percent of blending that is allowed based on the load is determined by a map that is stored in the software. The load value that the map uses is the load that is determined by the load feedback signal. The load feedback signal is determined by Electronic Modular Control Panel (EMCP) from the total real power as a percent of total rated real power of the generator set. That signal gets sent back to the engine ECM from the EMCP via Pulse Width Modulated (PWM) signal or J1939 message. That load is then used by the engine ECM to determine the maximum amount of gas blending that can be allowed
Generator Total Apparent Power: This is simply the product of the voltage times the total current flow and is expressed in terms of VA or kVA.
Generator Total Real Power: This is the product of the voltage times the component of the total current that is in phase with the voltage and is expressed in terms of W or kW.The ECM provides control of the air/fuel mixture to the engine. Illustration 2 is a diagram of the fuel system main components. The flow of fuel through a typical fuel system is explained below.Refer to the Application and Installation Guide, LEBW5336, "Gaseous Fuel Systems" for more information on fuel system specifications and installation. The publication is available from the Electronic Media Center.
Illustration 2 g03327877The fuel flows from the main gas supply through a knock-down regulator. A knock-down regulator is a second regulator that is needed when the gas supply pressure is too high for a single regulator to manage.From knock-down regulator, the fuel flows to the fuel filter. Usually, the fuel filter is a component of the design at the particular site. The customer is responsible for supplying clean, dry fuel to the engine. The fuel filter may be supplied by Caterpillar or by the customer. To prevent particles from entering the engine, a 1 micron filter is recommended. Use a filter that is properly sized for the required gas pressure.For installation of the fuel filter, the recommended location is close to the engine before the engine gas pressure regulator. Pressure gauges in the gas lines on each side of the fuel filter are recommended to monitor the filter differential pressure. A manual shutoff valve in the gas line before the fuel filter will facilitate servicing of the filter.The filtered gas flows to the Gas Shutoff Valve (GSOV). The GSOV may be supplied by Caterpillar or by the customer. The solenoid for the GSOV may be connected to engine wiring harness or to a harness that is supplied by the customer. In either case, the customer may install a switch that can interrupt the circuit.The control system is configured for a GSOV that is energize-to-run. This means that the GSOV must be energized in order for the engine to run. The GSOV may be energized by the customer equipment or by the ECM. When the GSOV is energized, the valve opens and the fuel flows to the engine. When the control system shuts down the engine, the voltage is removed from the solenoid. The valve closes and the fuel is shut off.The gas flows through the GSOV to the gas pressure regulator.The regulator may be supplied by Caterpillar or by the customer.A regulated pressure of 10.3 to 24.1 kPa (1.5 to 3.5 psi) is recommended.For parallel to utility applications, the required fuel pressure stability is 1.7237 kPa ( 0.25 psi).Less gas pressure may result in reduced substitution. More gas pressure may result in instability.
Illustration 3 g06164237
Flow of fuel through the single turbocharger arrangement
(1) Fuel control valveThe gas flows from the electronically controlled fuel control valve (1). The ECM issues a command signal to the fuel control valve via the CAN data link. The fuel control valve regulates the flow of gas to the engine.
Illustration 4 g03332680
(2) Air inlet tubes
(3) Turbocharger compressor
(4) Mixing tubesThe fuel control valve controls the volume of gas that flows to mixing tubes (4) attached to air inlet tubes (2). The inlet air that is necessary for combustion also enters the air inlet tubes. The air/fuel mixture enters turbocharger compressors (3).
Illustration 5 g03332755
Flow of air and fuel through the