On-Board Fuel Consumption Monitoring – The New Standard

August 22, 2024, 7 minute read

Targeting more environmentally friendly mobility, internal combustion engines is a constant focus point of the manufacturers and the governments. As fuel consumption has a direct impact on the environmental compatibility in terms of carbon emissions, NOX, fine particles emissions and so on, a new set of rules have been defined in Worldwide harmonized Light-duty vehicles Test Procedure (WLTP) and Real Driving Emissions (RDE).

New rules requires that the manufacturers implement OBFCM (On-Board Fuel Consumption Monitoring) systems which have an accuracy of simulated consumption better than +/- 5% compared to the real measurement. Actual compliant tests are run in real-life conditions with fuel flow meters installed in the fuel rail.

Today’s automakers are mainly relying on simulated data to determine or estimate the fuel consumption, this method provides an indication indeed in a large boundary domain under ideal operating conditions which are hardly achievable in the real-world operation.

Allengra solution of a dedicated on-board fuel monitoring device, minimizes external factors influence such as:

       -  Pressure variations

       -  Fuel & environment temperature

       -  Fuel specification & quality

       -  Overall system wear or aging

The common measurement technologies that could be used to measure fuels are:

       -  Mechanical flow meters

       -  Vortex flow meters

       -  Delta Pressure flow meters

       -  Coriolis flow meters

       -  Ultrasonic flow meters

The ultrasonic principle stands out as the ideal candidate which has also already imposed as the go-to solution in the motorsport for balance of power (BoP). As for the other technologies, they are failing either technically and/or commercially due to accuracy, size, suitability for in-car installation, vibration resistance, lifetime, influence on the engine functionality or price.

PUM Fuel Flow Meter

The key advantages of the ultrasonic principle are:

       -  High accuracy

       -  Non-intrusive

       -  No moving mechanical components

       -  Wide measurement range (low and high flows)

       -  High measurement frequency

       -  Suitable for on-board installation (resistant to vibrations and environmental conditions)

       -  Scalable

Due to the versatility of the ultrasonic principle, it can be produced in a compact and cost-effective way for the mass production, therefore every vehicle can come with the on-board fuel flow meter installed directly from factory, thus providing the users with real fuel consumption, along with a better understanding of the RDE.

With over a decade of experience, Allengra is the go-to manufacturer of Ultrasonic Fuel Flow Meters. A refined time-of-flight principle at the base for ultrasonic metering, combining it with other technologies, serving the automotive industry with just what it needs.

Due to the many ICE configurations and topologies, but also having a different measurement location with specific operating conditions, the measurement technology needs to support high flexibility. Therefore, our proprietary technology has the following highlights worth mentioning among others:

1. Pressures

  • Up to 20 barG after the low pressure pump or fuel supply systems specific to motorcycles
  • Up to 2200 barG after the high pressure pump for monitoring of the fuel injection process

2. Medium temperatures

  • From -40°C to 100°C under normal operation conditions
  • Cryogenic applications (e.g. in liquid hydrogen) or high temperatures up to 240°C possible under special handling

3. Ambient temperatures

  • -40°C up to 125°C covering both harsh winters but also installation close  to the engine or other heat producing elements

4. Vibrations

  • According to ISO 16750 and IEC 60068 standards

5. Flow measurement domain

  • measuring from 0 ml/min to 8000 ml/min with high precision
  • other flow ranges based on special requests 

6. Measurement frequencies

  • Up to 1 kHz for conventional fuel flow meters
  • Up to 6 kHz for fuel flow meters tailored for motorsport targeting limit of BoP to ensure anti-aliasing
  • Up to 100 kHz for fuel flow metering at the injector level so that the injection profile can be monitored and adapted in real time

7. Measurement channels

  • 1 measurement channel for simple and cost-effective applications
  • 2 – 3 measurement channels for high-end applications with redundancy or anti-aliasing requirements
  • Up to 32 measurement channels for monitoring the complete engine combustion cycle at the injectors level

8. Fuel type identification & compensation

  • Fuel grade, quality, temperature and pressures are influencing the measurement accuracy.
  • Allengra systems can be calibrated on specific fuels for ultra-high accuracy applications (<0.5%) or self-compensate based on built-in fuel identification feature