Please find detailed below an explanation of the operating principles of the G-volution Optimiser and its relationship with the OEM base engine.
The function of the OEM ECU is to control the engine. The most demanding part of which is the generation of the fuel control signals. These must be generated in real time to a high degree of accuracy. The fuel control signals are generated as the output from a closed loop control system, the primary input to which is throttle demand.
Because the fuelling is normally controlled solely by the OEM ECU, the fuel control signals are supplied only to the fuel injectors. Therefore, there is no requirement for the OEM ECU to either broadcast these signals or accept external inputs to modify them. Even if these features were added to OEM ECU SW and the CAN catalogue, the latency associated with external communications or other general purpose inputs / outputs would be too great to provide fuel control with the required accuracy and timing.
Optimiser Operation Characteristics and Benefits
Emulation of the primary injector pulse signals is the operation basis of the G-volution Optimiser.
Emulating and translating the primary injector control signals allows the original fuel demand to be mapped into individual demands for a number of fuels (primary, secondary, tertiary etc). This principle is protected by patent GB2372835 (owned by G-Volution). Additionally, patent GB2447046 (also owned by G-Volution) details the implementation and techniques necessary to modify the primary fuel injector control signal and generate a viable multi-fuel system. The Optimiser is unique as it is the only patented system of this type.
Operating in this mode provides a number of significant benefits.
The OEM ECU remains the master for the engine control loop. The Optimiser acts as a slave, translating the primary fuel control signals and managing the alternative fuel system. The Optimiser is effectively transparent to the OEM ECU and thus the original OEM ECU continues to operate normally.
The original engine power and torque characteristics are maintained because the engine is running on the original maps under the control of the original OEM ECU at all times. It is only the ratio of the diesel and natural gas used that is changed by the Optimiser. The Optimiser and alternative fuel system is calibrated to ensure that there is effectively no difference in the performance or response of the engine.
Because the Optimiser operates on the primary fuel control signals, it is inside the control system feedback loop. Therefore it works in sympathy with the control loop, rather than against it.
For example, as seen with other systems on the market, changing the throttle pedal demand or altering the fuel rail pressure to reduce the primary fuelling would perturb the control loop and potentially introduce instability or force it to a new operating point.
The fact that the Optimiser works in real time inside the control loop, means that it can operate effectively all of the time. Therefore there are no conditions which prevent operation on multiple fuels (including during gear changes and high transient operation).
Because of the OEM ECU retains control of the engine all of the emission control strategies remain unaffected. The start of injection (hence ignition timing), which is not affected by the Optimiser, nor is the control of EGR or SCR systems (if fitted).
The Optimiser does however provide the capability to change the ratio of the multiple fuels in real time dependent on the operation conditions of the engine. This provides a new degree of freedom in fuelling the engine, allowing optimisation for power, economy or emissions dependent on the characteristics of the individual fuels used.
The original engine control system (for automotive application) will normally be a safety integrity level (SIL) 2 implementation. Because the original OEM ECU is unaffected and continues to operate normally, the original system safety case will not be compromised.