Page 10 - Industrial Technology Extra 12th October 2020

The high pressure of EFI means that, even at
high altitudes, the amount injected is continuously
electronically calculated based on data such as
temperature, air pressure and required
performance. Because the pressure helps create an
extremely fine vaporisation of fuel, it ensures a
consistent mix of fuel and air. As a result, using an
To achieve extended flight times using minimal injection system is able to increase fuel
fuel quantities, these aircraft require reliable consumption by as much as 30 per cent.
propulsion systems. Previously, the only way of
achieving fuel delivery to the engine was done by a Small planes, small motors
carburettor to provide a combustible mixture of fuel When designing an injection system for a small
and air. However, a carburettor is unable to provide aircraft, everything needs to be minimised. The
an optimum mix of fuel for all of the various phases compact system consists of many components,
of the flight. including the injector, a fuel pump, ignition module
In place of a carburettor, smaller aircraft and a fuel pressure accumulator. These mechanical
manufacturers are increasingly beginning to components need to weigh just a few hundred
consider electronic fuel injection (EFI) to provide the grams and take up as little space as possible in
benefits of fuel injection to small UAVs. The system order to save space and help keep the aircraft light.
works by injecting fuel, which is under pressure in A high-performance, low-weight DC micromotor,
the system, into the intake manifold using special such as the Faulhaber range supplied by EMS, can
injectors and the fuel-to-air ratio is electronically fit compactly into an EFI system to help deliver
controlled using a control unit. Sensors in the intake consistent fuel pressure. The motor helps create the
and exhaust system of the engine, feed data to an auxiliary energy required to build up the necessary
electric control unit, where it is then assessed, and pressure, which powers the fuel pump to deliver
the ideal amount of fuel required at a particular fuel and air into the system. Motors must be able to
point is calculated. work tirelessly, with low rotor inertia for fast and
The right balance of fuel and air in an engine is reliable acceleration and braking. As Faulhaber
required for it to burn, so the sensors also help the motors are also characterised by their high power
system to fine-tune the mixture for the load and and low weight, they form part of this important fuel
conditions at each precise moment of the flight. system without contributing to any unnecessary
Efficient fuel consumption is especially weight gain.
important in UAVs, where every gram of weight Just as the desire for light aircraft may have
saved helps extend flight time or increase the usable developed significantly since the Wright Brother’s
load. Another issue with carburettors is the invention, the need to economise fuel consumption
inconsistency of the fuel mixture they achieve. If the won’t cease to grow in importance any time soon.
mixture is too rich at altitude, it’s perfect at sea From supplying a lightweight solution to highflying
level. Conversely, if it’s ideal at altitude, it is too travellers, to helping smaller aircraft make the most
weak on the ground. This compromise leads to out of their fuel, micromotors are key to helping
reduced performance and increased fuel developments in the aeronautical industry take off.
consumption. www.ems-limited.co.uk

October 2020 • INDUSTRIAL TECHNOLOGY EXTRA • p10