Mercedes AMG PETRONAS F1 team unveils 2014 challenger and PU106A Hybrid Power Unit; new fuel and lubricants
|The PU106A Hybrid Power Unit. Click to enlarge.|
The Mercedes AMG PETRONAS (Petroliam Nasional Berhad) Formula One Team unveiled the F1 W05, its 2014 challenger, at the Circuito de Jerez in southern Spain. Designed from the ground up as an integrated project between the Mercedes-Benz teams based at Brackley and Brixworth, this new car—the first all-new Silver Arrow to hit the track since 1954—comes in a year when Mercedes-Benz celebrates 120 years of motorsport and the 80th anniversary of the Silver Arrows.
The F1 W05 will deliver more than one-third more performance from every unit of fuel consumed. At the core of the racer is the new PU106A Hybrid Power Unit designed to meet the new philosophy and resulting requirements of Formula One. A maximum race fuel allowance of 100 kg per race, coupled with a maximum fuel flow rate of 100 kg/hour, focused development efforts on delivering performance with a set of new technologies that achieve the efficiency gain of more than 30%.
The initial discussions between the FIA and the engine manufacturers were focused on delivering a more efficient internal combustion engine and more potent Hybrid systems. Both sides were keen to move the sport in this direction. With a normally aspirated engine, the power potential is controlled by the flow of air into the engine via the capacity and the rpm it can be run at. However, the automotive industry is focused not on air consumption but on fuel consumption—and the CO2 emissions this generates. The sport has therefore turned the rules on their head with a formula where the performance is restricted by two fuel mechanisms: a maximum fuel flow rate of 100 kg/hr and a maximum race fuel allowance of 100 kg. The fundamental challenge is to convert as much of the chemical energy in the fuel, into mechanical energy, as efficiently as possible at the prescribed flow rate. Conversion efficiency is now the key.—Andy Cowell Managing Director, Mercedes AMG High Performance Powertrains
|The F1 W05. Click to enlarge.|
|Select 2014 F1 powertrain regulation changes|
|Engine. The 2.4-liter, normally-aspirated V8 engine used from 2006 to 2013 is replaced by a turbo 1.6-liter V6 with high pressure direct injection up to a maximum of 500 bar. Maximum engine speed is reduced from 18,000 rpm to 15,000 rpm. The fuel flow rate of the new ICE must not exceed 100 kg/hour; this maximum rate can only be achieved above 10,500 rpm.|
|Turbocharger. A sole single-stage compressor and single-stage exhaust turbine are used for pressure charging. Size and boost level of the turbocharger are free. Measures must be taken to ensure that, in the event of failure of the turbine wheel, any resulting significant debris is contained within the car.|
|Energy Recovery Systems (ERS). Energy can still be recovered from and deployed to the rear axle, however this is now termed MGU-K ( Kinetic) and is permitted twice the maximum power of the 2013 motor (120 kW versus 60 kW). It may recover five times more energy per lap (2 MJ versus 400 kJ) and deploy 10 times as much (4 MJ) compared to its 2013 equivalent, equating to more than 30 seconds per lap at full power. The rest of the energy is recovered by the MGU-H (for ‘Heat’); an electrical machine connected to the turbocharger.|
|Gearbox. Gearboxes now have eight forward ratios—one more than previously—and the gearbox, including ratios, must now last for six races; one more than the previous five.|
|Minimum Weight. To compensate for the increased weight of the powertrain, the regulations stipulate a new minimum weight limit for the car of 691 kg, up from 642 kg in 2013. Within this allowance, the Power Unit itself must have a minimum weight of 145 kg.|
|Exhaust. Unlike previously where two exhaust tailpipes were used, the 2014 regulations mandate the use of a single, central exit tailpipe through which all exhaust gases must pass.|
|Brake System. Owing to the increased energy recovery requirements on the rear axle, the rear brakes may now employ a ‘brake-by-wire’ system. The brake system must comprise two separate hydraulic circuits for the front and rear wheels operated by one pedal. The system must be designed so that if a failure occurs in one circuit, the pedal will still operate the brakes in the other.|
Under the new F1 regulations, the engine has been formally replaced by the Power Unit, comprising six separate elements: the Internal Combustion Engine (ICE); Motor Generator Unit-Kinetic (MGU-K); Motor Generator Unit-Heat (MGU-H); the Energy Store (ES); the Turbocharger (TC); and Control Electronics (CE).
The performance specification of the Power Unit for the 2014 season must be homologated on 28 February. After this point, only modifications for cost and reliability reasons are permitted. 8% of the current Power Unit will remain homologated at the end of the season, with 92% development freedom for 2015.
Per the regulations, the Mercedes team downsized their internal combustion engine (ICE) to a 1.6 liter V6 configuration and down-speeded to a maximum of 15,000 rpm. To achieve high power delivery and therefore efficiency from the ICE, a pressure charging system has been introduced, in the form of a single stage turbocharger and compressor.
The new Hybrid Energy Recovery System (ERS), which incorporates electric motors capable of recovering both kinetic and waste heat energy, presented a ten-fold greater challenge than its predecessor, KERS, introduced by Mercedes-Benz in 2009.
Our learning during the KERS project was the bedrock for building ERS. But we are talking about a big step not just in absolute power but probably more significantly in terms of duty cycle, in other words the percentage of the time around a lap that it is operation. You could in theory combine two of last year’s KERS motors on a single shaft to achieve the maximum power of 120 kW. But instead of using the motor for just short of seven seconds per lap as we did last year, now it’s on for over 30 seconds of every lap. And there is also a much greater reliability requirement, because there are only five of these motors per driver per championship. So it’s more power, a harder duty cycle and significantly greater reliability demands. What’s more, it’s no longer something that’s ‘nice to have’ – given the power and the duty cycle, the car will be seconds slower without the MGU-K working, so you need it to do laps. Stitching all of that together with an absolute deadline is a big challenge, probably to an order of ten times more challenging. And that’s just one of the six parts of the Power Unit we are producing.—Andy Cowell
Fluids. PETRONAS scientists developed a new fuel for the 2014 Power Unit, balancing characteristics such as energy density, octane number and volatility with careful consideration of the mandatory fraction of the fuel that must be of bio-origin.
This posed a challenge as some of the best components for delivering high, smooth power are also those that likely lead to deposit build-up in injector nozzles. An extensive development program involving chemists and engineers testing new fuels in real engines has resulted in a new generation fuel for the V6 that promises to deliver a significant gain in performance.
The smaller engine and increased power per liter mean that it runs hotter. Oil thins at higher temperatures; thus, a hotter engine needs a thicker oil to stop metal components from rubbing together and failing. However, the hotter conditions and reduced quantity of oil in the ICE (reduced from almost seven liters for the V8 to fewer than three liters for the V6) also mean that the oil must contribute more to cooling the engine. This requires thinner, faster flowing oil.
Additionally, the regulation changes restrict the quantity of fuel that can be consumed per race to 100 kg, which means that the oil needs to help conserve energy by minimizing friction. Again, this requires thinner oil.
In order to meet these complex and contradicting requirements, the new engine oil for the 2014 car is a precisely balanced mixture of advanced, thinner synthetic base oils to help cooling and polymer viscosity boosters (which kick-in at higher temperatures) to thicken the oil. Friction-reducing oil components, which make it easier for metal surfaces to slide past each other, have also been used to improve overall fuel economy.
Another consideration is that the higher temperatures also make it more likely that the oil itself will stop working properly. High performance additives have been included to stop the oil from breaking down under these extreme conditions.
Energy losses in the gearbox can also have a significant impact on fuel economy. To address this, PETRONAS technologists have also produced precision gearbox lubricants for the 2014 car to ensure that energy losses in the transmission are kept to a minimum, while making sure that the gearbox is protected from failure.