UWE Bristol Engineering showcase 2015

Joshua Minto
MEng Motorsport Engineering
Project Supervisor:
Dr. Mike Ackerman
Investigation and Design of a Throttle-less Engine
The Drive for Efficiency
Automotive Engineering is an area that sees constant improvements and innovation, particularly in regard to the internal combustion
engine, as regulators and consumers move increasingly toward improved emissions and fuel economy. One such area for potential to
see increased efficiency is the inlet stroke, as it is the induction of air into the cylinder which contains a lot of the frictional losses.
Therefore, removing the throttle plate and controlling the air intake via an alternative means, in order to create a throttle-less engine,
will remove most of the restrictions associated with the inlet process, therefore improving the overall efficiency.
Project summary
The project is based on the idea of controlling
the air intake to an internal combustion
engine not with a throttle plate, but by
varying the valve opening duration, in order
to reduce pumping losses as much as possible
Project Objectives
The objectives of the project were to develop
a simulation of throttled and throttle-less
operation and compare the two, and
investigate the means by which this can be
achieved through camless actuation of valves
PV Diagrams
A numerical simulation of an engine was created in
order to obtain pressure data across the cycle, and
plot it against volume in order to produce a PV
(pressure-volume) diagram. These are a very useful
tool in engine analysis as the area inside the lines
that are produced shows the work produced and
done by the engine, where the upper and large
loop shows the work gained, and the lower loop
shows the frictional losses due to the gas exchange
processes, and is known as the pumping loop.
Proof of Concept
In order to demonstrate the feasibility of electromechanical actuation, a test rig
(left) was constructed using a generic valve, inside which 10 disc magnets were
inserted, and a solenoid. Using the equipment shown in the image on the right,
it was possible to create a signal to actuate the valve with opening and closing
durations that could be set by the user, though in a real application, they would
be determined by a program based on a range of inputs
Reducing the Pumping Loop
The images shown above are close up views of the
pumping loop, with that on the left being a
superimposed image of the throttled and throttleless
models, where the upper lines are part of the
compression and exhaust strokes, which are the
same for both models, but the lower two lines show
the different intake strokes. The upper of these is
from the throttle-less model whilst the lower is the
throttled, demonstrating that a considerable
reduction in pumping work can be achieved.
Bigger Benefits at lower throttle angles
The two images on the right again show the
pumping loop for throttled (top) and throttleless
(bottom) operation of the simulation,
however, this was performed with much lower
throttle openings and cylinder air masses than
the image on the right. This shows how the
restriction due to the throttle is larger at low
throttle angles, and how throttle-less operation
greatly reduces the work required for lower
cylinder air mass requirements.
Project Conclusion
This project has shown the potential that
exists not only for throttle-less operation, but
particularly its application alongside camless
valve actuation to provide a more efficient
means of air intake to a gasoline internal
combustion engine. The simulations created
are an effective way of demonstrating the
differences between throttled and throttleless
operation, in particular the benefits of
the latter, especially at low throttle openings.
Overall, it has been shown that there is a
clear benefit to using throttle-less rather than
throttled operation as a means to control air
intake, not just in replacing the throttle plate,
but also in actuating the valves without a
cam, and has shown the suitability and
potential of doing this via electromechanical
means.