Spark anemometry based on the analysis of an electrical discharge can be implemented in the automotive sector through measurements of the secondary circuit voltage. Actual applicability of this method is quite limited, given that it requires additional hardware that is not compatible with space requirements specific for production engines (e.g. fueled with gasoline, LPG or methane); furthermore, applying high voltage measurements is complex and entails increased cost. This is the main reason why the existing spark anemometry method is limited to research applications. Instead, we are proposing a new technology that represents an alternative solution with contained cost but with the same effectiveness; it requires no additional hardware given that it is based on the characteristics of inductive ignition systems (already present in the vast majority of spark ignition engines).
More to the point, the proposed methodology features a starting point based on secondary current measurements (rather than secondary voltage) so as to estimate the in-cylinder fluid velocity around the spark plug during ignition. Even if it requires a calibration phase on a dedicated flow rig, the technology is completely non-invasive in terms of actual application on power units (with a wide range of displacement and configurations). In fact, once the coil and spark plug characteristics are defined, implementing the measurement is relatively straight forward, through the parameters identified during the calibration phase.
Innovation beyond the state-of-the-art is clear when considering that no additional hardware is required and the simple application on real-world systems; the most complex aspects of the methodology are related to the calibration phase.
Impact on actual applications can be identified through the possibility of defining optimal control strategies for various engine speed and load conditions, with ignition timing specifically adjusted for each cylinder. These control algorithms are based on the evaluation of fluid velocity close to the spark plug, with an emphasis on reducing cyclic variability. This approach allows significant efficiency increments, directly applicable on new or existing power units. The potential reduction of fuel consumption is even more noteworthy in “extreme” working conditions such as high levels of exhaust gas recirculation (EGR), lean fueling and the use of alternative fuels such as hydrogen.
Innovative aspects
- optimal ignition control tailored to actual in-cylinder conditions
- the technology does not require additional components for power units equipped with traditional ignition systems (i.e. inductive type)
- possible implementation of the control algorithm trough ECU software updates, therefore ensuring ample market potential
- completely compatible with standard ignition diagnostics
- fuel economy benefits are even more prominent in extreme conditions such as high levels of EGR, ultra-lean fueling and the use of alternative fuels such as hydrogen
Competitive edge
The technology offers significant competitive advantages in the reference automotive market; spark anemometry can also be applied on stationary engines, even if the off-road market can be heterogeneous to a high degree in terms of control methods. Given the current state of emerging technology, evaluating critical aspects is somewhat difficult and features high level of uncertainty. Nonetheless, two major bottlenecks were identified for the automotive market. Implementing spark anemometry on new power units is limited by the willingness of the OEM to include it in the ECU. On the other hand, for existing engines, the end user plays an essential role; dedicated promotion actions that convey the main advantage of fuel economy benefits should ease implementation in the legacy fleet as well.
The only technology identified as a competitor at this stage is spark anemometry based on secondary voltage measurements; reduced applicability of this method is the main reason why it is not present on the market. The advantages of the proposed technology makes it possible to implement in-cylinder fluid measurements on a wide scale and to develop optimal control strategies aimed at improving fuel economy.