Issue: May 2016


Axle technology helps put the fun into driving electric and hybrid vehicles



by Nick Palmen

OEMs have no choice but to offer hybrid or electric cars in markets such as Germany.

An independent online survey commissioned by GKN Driveline found that around half of the one thousand people who responded to the survey (49%) expected their car dealership to offer a plug-in hybrid option. Some 52% agreed that their perfect car would combine plug-in charging with all-wheel drive.

The poll of motorists showed that 75% preferred the idea of plug-ins, with 61.2% agreeing that an electric range of 50km would meet their daily needs. There is, however, still some way to go to gain full market acceptance. Around 81% of respondents said they were wary of hybrids, with 62.8% citing “poor value for money” as the main reason. Conversely, just 25% described all-wheel drive vehicles as “expensive” to purchase or run. They associated the technology with off-road capability (73%), safety (37%) and higher performance (36%). Automotive Industries (AI) asked Peter Moelgg, President of Engineering, GKN Automotive, what GKN sees as the future of electric drive technology.

Moelgg: The market for electric and hybrid vehicles is currently small, but there is no denying the direction of travel is growth. Most OEMs now bring out an all-wheel drive variant of their models and increasingly they are launching an electrified version as well. That will become more and more common.

GKN believes that within the next 10 years, 40% of all new vehicles will have some form of electrification and we are focused on being the leading supplier of electrified driveline technology on a global basis. We don’t just see demand for electrified vehicles concentrated in the US or Europe, but in markets such as Asia and, particularly, China. We already have strong heritage in the area of electric mobility, with nearly 300,000 GKN electric axles on the road and our successful involvement in programs such as the BMW i8, Porsche 918 Spyder, Volvo XC90 and S90, BMW 2 Series Active Tourer and Mitsubishi Outlander.

Our focus going forward is on developing electrified driveline technology that pushes the market forward by making cars better to drive through additional functionality, and making our electric drive modules smaller, lighter and more integrated. We have the proven capabilities and experience in this market and we are using that experience to develop the next generation of technologies.

What additional functionality can we expect to see from EVs or hybrids?

Moelgg: One particular area we are looking at is improving the drive appeal of electrified vehicles, making them as dynamic and enjoyable as conventional powertrain architectures. There are already some great vehicles out there, such as the BMW i8, but to increase the desirability of electrified vehicles you need to make them attractive from a performance point of view, as well as efficiency. The eTwinster system we recently demonstrated at our Wintertest event in Sweden introduced torque vectoring to electric vehicles, making the driving experience far more dynamic for the motorist. This combines the GKN twin-clutch Twinster technology seen on the Ford Focus RS and Range Rover Evoque with our eAxle technology seen on programs like the BMW 2 Series.

AI: What are your customers asking for? Do they want more power from their hybrid vehicles?

Moelgg: There is certainly a trend towards electric drive systems that can handle more power from the electric motor. If you look at early electric axle applications, for example, the requirement was to deliver around 1,000Nm of torque and a speed of 60Km per hour, whereas with current applications the minimum is 2,000Nm to 2,500Nm of torque and a minimum speed of 200Km per hour. We are talking to customers about levels beyond 3,500Nm plus, as they look for the electric element of their vehicles to provide the majority of the motive power and for the internal combustion engine to be downsized to a supporting role. The hardware on these vehicles is only part of the story. Our systems integration experience is what sets up apart. Axle-split hybrid vehicles are actually not easy to tune. They can be run in front-wheel drive, rear-wheel drive, battery-only or a blend. And drivers don’t want to be able to notice which mode the vehicle is in. They expect the car to behave in the same way repeatedly and predictably. We specialize in delivering this.

AI: GKN’s technology has focused on powering the opposite axle to the IC driven axle. What benefits does that offer?

Moelgg: An eAxle is used in a so called “through-the-road” hybrid where the primary axle is driven by a combustion engine, while the secondary eAxle is driven by an electric motor, providing parallel hybrid and pure electric drive capability. The eAxle applies electrical torque direct to the vehicle’s axle, instead of hybridizing a conventional transmission. If the engine drives the front wheels, the eAxle drives the rear – and vice versa.

The torque goes from the electric motor to the eAxle via either a single or multi-speed gear train before passing to the drive shafts. The additional gear reduction enables smaller electric motors to deliver more torque to the wheels – and more immediately.

eAxles don’t just hybridize the car – they also give it electric all-wheel drive. This means a lot more options in terms of how the vehicle’s torque is tuned, blended and balanced.

Conventional all-wheel drive technology is improving with the use of disconnect systems, so the fuel penalty of choosing all-wheel drive has diminished. However, if you create all-wheel drive through hybridization, you receive all of the traction benefits but with a fuel saving of around 30% to 40%. That is a compelling argument for the consumer.

AI: You say that the balance of power will shift from the internal combustion engine to the electric motor. What is the catalyst for that change?

Moelgg: There is a dual push. Governments around the world are demanding cleaner, greener, more efficient cars and, importantly, consumers want them. If there is push without any pull, then the growth of electrified vehicles would stall, but you have seen with the success of the likes of the Volvo XC90 T8 Twin Engine or the Mitsubishi Outlander PHEV, that consumers like and want these vehicles.

As electric motors – or other alternative fuel sources - evolve and become more powerful, then the ICE will naturally become smaller and will simply complement the electrified power. There is still scope for improvements in the technology but you are already seeing high-end sports cars with ICEs normally seen in small city cars because the electrified power source is so sophisticated.

AI: When can we expect to see electric or hybrid vehicles as a mainstream, mass market product?

Moelgg: It’s already happening and the pace of change is accelerating. If you look at the number of new recent vehicle launches, many have been HEVs and automakers are stating their intention to grow sales of electrified vehicles. Volvo recently said they expect to sell one million electrified cars by 2025, which is a clear sign to consumers and the market that they are serious about this segment. The arguments about infrastructure remain, but they are being addressed.

AI: What role will 48V applications have in increasing the adoption of electric vehicles?

Moelgg: We see a key role for 48V technology, particularly for enabling mass electrification. We are developing a 48V ap­plication, which we expect to showcase to customers during the next 12 months.

AI: GKN recently launched its eTwinster. Can you explain the technology and the thinking behind the development?

Upgrading an eAxle to vector torque is relatively simple. And it makes particular sense for rear-axle hybrid modules. To control the torque at each individual wheel, you just need to replace the eAxle’s differential with a twin-clutch system like GKN’s Twinster technology.

Plug-in hybrids are ideal for torque vectoring because hybridization changes the weight distribution and behavior of the base vehicle. If a car maker wants to offer performance without compromising their CO2 scores, then a plug-in hybrid with torque vectoring gives them a lot of freedom to deliver. The vehicle response is extremely gratifying to drivers, even in large hybrid SUVs.



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