I wrote this brief study for my physics coursework and I thought it would be suitable for a blog post. As I found out during this write-up, information about KERS is extremely hard to come by as it is a very secretive area of engineering. I’ll have all my references at the bottom but before you read, it is worth mentioning that this is not a truly reliable study. I have done the best I can with the information I have found and I would like to thank Craig Scarborough (@ScarbsF1) for pointing me in the right direction on occasion. Enjoy!
Most hybrid vehicles today utilise a rechargeable electric motor running alongside an Internal Combustion Engine (ICE), which in turn generates the electricity needed to power the aforementioned motor. In terms of satisfying changes needed to combat climate change, hybrid vehicles are arguably a step in the right direction. However all-electric power is an even more sustainable solution but they require an alternative energy source (hybrids use the mechanical movement of an ICE) to generate the electricity needed to power the electric motor.
In years gone by, the Motor-Generator Unit (MGU) has primarily been used to convert currents. However over the past decade this technology has been harnessed to increase the efficiency of vehicles, more specifically road-going vehicles such as cars, buses and lorries. MGUs, in the motoring world, can now be referred to as energy recovery systems, their most common application being in how they recover energy that is normally lost under braking.
Work is done at the brakes (by friction) to slow the vehicle down and this dissipates heat energy as a result of the contact between the brake pad and the braking surface (e.g. a disc). This lost energy can be recovered by inputting a generator into the drive system. When the vehicle is under deceleration, the generator harvests this previously lost energy – it acts as a highly resistive force when generating electricity so less force is needed on the braking surface. Therefore less work is done at the brakes and thus less heat is dissipated. Energy has been recovered from the braking phase which can now be used for other purposes, such as powering an electric motor that provides a drive for the vehicle.
These are the basic principles of the Kinetic Energy Recovery System (KERS). It recovers kinetic energy normally lost under braking, stores it (in a chemical or mechanical energy store) and is then used to power the vehicle during acceleration. KERS is, effectively, a glorified MGU: it is well-known for its use in Formula One over the past five years although the technology has expanded rapidly into road cars and other forms of motorsport.
Although it has not cropped up extensively in the media, braking (in particular brake bias and control) will be an important design consideration for 2014. This is down to the introduction of the new power units, which – due to the additional recovery power of the MGU-K – makes the bias difficult to adjust and control.
Current Braking System and KERS
In this section of this post I am going to break (pardon the pun) down the key characteristics of the current (2009-2013) braking system and how each component affects each other.
Since 2009 (excluding 2010), Formula 1 has utilised the Kinetic Energy Recovery System (KERS) that increases the efficiency of the braking system, transferring the previously lost energy to a battery. This energy can then be used to provide an additional boost of power at the driver’s disposal for 6.67 seconds per lap. The KERS harvests 60kW of power, which equates to about 80bhp – about the same power as a small family hatchback car.
It does this via a Motor Generator Unit (MGU). As the driver brakes, the engine drives the generator of the MGU which acts as a resistive force to the driveshaft connected to the wheels. The MGU transfers the energy recovered from the generator to the battery. When the driver pushes the KERS button the energy is sent back to the motor of the MGU, adding power to the engine.
2014 presents the biggest change to Formula 1 cars since the late 1980s: gone are the naturally aspirated 2.4 litre V8 engines and in their place a 1.6 litre V6 turbo is introduced. To make matters more complex the engine manufacturers must apply complex energy recovery systems to boost power output, reduce fuel consumption and further reduce the number of engines allowed per driver per season to lower costs. The idea behind this is to bring F1 technology more in line with road car development.
The last time turbo power was in F1 was during the 1988 season. Honda dominated this era with McLaren, using a 1.5 litre V6 in the famous MP4/4 before being replaced by a 3.5 litre naturally aspirated engines for the following season. Technology has moved on drastically since then. The 2014 power units have the potential to decide the world championship such is their importance. The manufacturer who meets their side of the bargain will have a huge upper hand on the opposition. They are therefore the most likely component to give the biggest performance factor.
What are Power Units?
The engineers no longer refer to the next generation of F1 powertrain as “engines”. They are now dubbed as “power units”. The reason behind this being that the powertrain is made up of more than just a combustion engine/turbo, there are more complex elements involved from this season onwards. The recovery systems on board will generate enough energy to supply plenty of extra kick via an electric motor, with the additional power output mapped into the engine system to provide more performance at optimal stages of the lap (i.e. the driver will no longer have to push a button to use the additional power available).
Facts & Figures
Let’s get into the numbers, starting with the turbo-charged engine itself.
Capacity: 1.6 litres
Maximum rpm: 15,000
Maximum fuel flow rate: 100kg per hour at 12,000-15,000rpm
*Estimated figure. Rumours of some manufacturers extracting a higher power output (notably Mercedes) at this stage of development.
Energy Recovery Systems (ERS):
Power output: Additional 161bhp for 33.3 seconds per lap
Maximum harvest energy: 2MJ per lap
Maximum energy output: 4MJ per lap
Battery weight: Limited to 20-25kg (must be placed beneath the fuel cell as a single unit)