Spark Ignited and Direct Injection
- Fuel cost savings
- Clean Emissions
- Fully rated horsepower
- Retrofit system – expands capability and adds value to your present investment
- Lower maintenance costs & improved longevity due to cleaner fuel
- Appropriate for rail or stationary applications
- Environmentally responsible technology
Low Pressure Direct Injection
The EE spark ignited prechamber (SIP) natural gas conversion is designed for the EMD 2-cycle diesel engines. It utilizes a low-pressure direct injection system, a prechamber spark ignition system, and an advanced full-authority electronic engine controller.
By means of an electro-hydraulic valve incorporated into the head, natural gas is injected into the cylinder near the bottom of the piston’s stroke when cylinder pressures are low. This requires far less injection pressure than late-cycle injection, and allows fuel and air to mix thoroughly during compression. The system achieves full rated engine horsepower with only 120-150 psi of injection supply pressure.
The EE Spark Ignited Prechamber is installed in place of the EMD diesel injector, and at the top of the piston’s stroke provides enough ignition energy to light the lean mixture of natural gas and air in the main combustion chamber. This oil-cooled prechamber is supplied with natural gas separately from the main chamber, and the engine controller is called upon to continuously adjust the prechamber air-fuel ratio for ideal ignition.
In order to reduce emissions and improve the quality of combustion at low engine speed and load, EE employs innovative control techniques to manipulate combustion characteristics. A spark ignited, 100% gas EMD engine runs smoothly from Low Idle to Notch 8.
EE chose to use low pressure injection over a high pressure system for a number of reasons. Low pressure injection:
– Extends the life of injectors and other fuel system components
– Improves the safety of the working environment on and around the engine
– Makes the fuel system simpler and more cost effective
– Avoids the complexity and energy consumption of a fuel pressure boosting system
These benefits of the ECI design translate into cost savings in both the initial investment and the operation of the equipment.
100% Spark Ignited Details
At the heart of the SIP conversion are the specially designed EE pistons and heads, originally developed for and used in the EE dual fuel conversions.
The piston design incorporates a lower compression ratio and a modified crown shape to provide maximum power with natural gas.
The modified head is based on the OE EMD design and is specially cast to accommodate the EE Gas Injector Valve (GIV).
This combination of purpose-designed head, piston, and specialty hydraulic/electronic gas injector valve is the polished product of years of development.
The power assemblies are applied using the standard diesel pack installation procedure, making the conversion straightforward and possible in any shop equipped for the overhaul of standard EMD engines.
System operation is governed by EE’s patented electronic control unit, or ECU. The ECU uses industrially proven electronic technology together with custom software to monitor and manipulate critical engine functions through a variety of sensors. It controls fuel injection timing, ignition timing, engine speed and generator excitation, smoothly handling wheel slip and traction motor series-parallel transition. The ECU is able to detect cylinder temperature imbalances, gas leaks, and equipment failures.
The ECU allows a maintenance technician to communicate with the system using either a simple digital information screen or a laptop computer and EE software.
The EE technician tool software can be run on a Windows laptop and allows a real-time, graphical display of critical engine parameters.
Cellular modem transmission capabilities are also available, which allow for data acquisition and fault history reviews from remote locations.
In order to achieve full rated power on turbocharged diesel engines, there are modifications made to the existing engine air cooling system. Additional radiators, more effective aftercoolers, some piping and the addition of water circulating pumps work to reduce the high temperature air the turbocharger produces. This equipment fits easily inside of the long hood, with the addition of contoured sheet metal necessary for the new radiators. On LNG-fueled equipment, supplemental cooling is also claimed from the vaporization of the liquid natural gas on the fuel tender.
The additional air charge cooling is not required for roots-blown engine conversions.