Question: what type of truck engines do you investigate for your phd

John Welford answered on 28 Jun 2012:

Hi matthew2000,

I look at turbochargers that go on the truck engines. These are usually big diesel engines.

As you might know engines work by creating explosions in their cylinders, the explosion makes the gas inside expand and the expanding gas pushes a piston. The piston turns a crankshaft and the crankshaft drives the truck (through a gearbox).

So to make the engine more powerful we want to create a bigger explosion. To do that we need to put in more fuel (diesel) and also more air. To put more air in to the cylinder we either need to make the cylinder bigger, or we need to compress the air.

To keep our engine nice and small (and therefore light and cheap) it is a good idea to go with the compressed air option. It is the job of the turbocharger to compress the air.

When you press the accelerator in a car (or a truck!) the amount of fuel delivered to the cylinders changes, and so the amount of air that is supplied to the cylinders also needs to change. To change how much the turbocharger compresses the air we need to move part of the turbocharger. This is where the electric motors come in. They change the position of parts in the turbocharger to change its performance.

It’s not a very nice environment to put an electric motor in as it is very hot and it vibrates a lot near the engine. It also has to be very reliable as trucks are expected to last a long time and drive hundreds of thousands of miles.

Phew – That’s quite a long explanation to give you just a little bit of an idea what I do. Let me know if any of it doesn’t make sense!