The engine in the wheels (s) of an electric car, few models are currently equipped, but their multiple qualities could well attract many manufacturers in the future. For the moment, only some sportsmen have the right, but in the future, this engine architecture could well equip our everyday cars. Decryption.
Although simpler technically speaking than a thermal, the electric car evolves slowly but surely with the advent of this energy. If the basic diagram remains the same overall, with a battery that causes one or more electric motors, the techniques are evolving to gain power, autonomy, aerodynamics, etc.
In short, the electric car continues to evolve and it does not only evolve for ten years, when it began to emerge on a large scale with the Renault Zoé, Nissan Leaf and other Volkswagen Golf Electric and Tesla Model S. The electric car, we can go back to the beginning of the last century to discover the premises.
And necessarily, who says last century, says Ferdinand Porscheone of the great automotive craftsmen at that time. He was not only a genius car engineer; He was also a pioneer in electromobility. As early as 1900, he designed an electric lead electric vehicle, whose limited autonomy was quickly compensated by the addition of a thermal engine, in a way anticipating the concept of electric car with autonomy extension.
This first model also introduced a rather interesting technical innovation: Rolding engines, or engines integrated into the wheels. This technology, still marginal today in the automotive industry, nevertheless seems to be a brilliant future. Really ?
What is the engine to the wheel?
Unlike conventional electric motors known as « inboard »installed inside the chassis between the axles, The wheel engines are directly housed in the wheels. They thus eliminate the need for transmission trees, differentials or gearboxes. Each engine directly transmits its power to the wheel, offering a transmission without intermediary, more direct and potentially more efficient.
Among the most often cited advantages of wheeled engines, we find in particular Simplification of design. Indeed, freeing classic mechanical constraints, manufacturers can rethink the architecture of their platforms. This allows in particular to enlarge the interior space or to integrate a larger capacity battery to benefit from better autonomy.
The engine-wheel also has another advantage, since it allows Reduce mechanical losses. In thermal vehicles as in electricity, energy is partially lost on the way through the mechanical components. The engine-wheel, by removing these intermediaries, promises a higher energy efficiency.
And the advantages do not stop there. Thanks to autonomous engines by wheel, it becomes easier to offer traction, propulsion or all -wheel drive versions, simply by changing the number and arrangement of engines. It is a boon for manufacturers, especially start-ups, who must optimize their development costs.
The Individual management of each engine Allows you to go far beyond what a self-locking differential can offer. The management of power to the wheel becomes more fine, adaptive, and programmable, which improves stability, handling and even sports performance in certain cases.
Why does this technology struggle to become widespread?
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As you can see, there are many advantages compared to a classic engine “posed” simply under a hood. However, the drivers are struggling to win on the market and particularly on our high series cars. And as you should suspect, several obstacles, technical and economic, slow down their adoption.
One of the main reproaches addressed to the engine motors by engineers concerns The increase in non -suspended massthat is to say the weight of the elements (wheels, brakes, etc.) which are not supported by suspensions. The more this mass is high, The more the dynamic behavior of the vehicle deteriorates. This affects driving accuracy, handling and comfort, especially on degraded roads. This becomes a drawback for a sports car, but it is generally rather well compensated for the advantages that this offers.
Some manufacturers, such as Mercedes, explore tracks to integrate the brake discs directly into the engines in order to compensate for this overload. But this in turn introduces additional technical complexity, reducing the initial gains in simplicity. The snake that bites its tail in short.
Installed directly in the wheels, The robe engines are more exposed to shocks, vibrations, dust, water, snow, or even salt used to clear the roads. All these elements can damage mechanical and electronic components, reduce their lifespan or generate breakdowns. Long -term reliability remains a question mark today.
Cooling is also another puzzle for engineers. If the brakes sometimes benefit from a directed air flow, cool a compact electric motor housed in a wheel – without access to a liquid cooling circuit – is a more difficult task. Excessive warm -up harms the components’ yield and longevity.
In order not to fix anything, the high voltage cables transporting the energy to the wheels are subject to frequent movements. In the event of an accident or loss of a wheel, they can break and expose drivers under tension, posing a serious risk for occupants and help. Safety devices exist, but they still increase the complexity of a system supposed to be “simple”. Again, the snake that bites its tail …
Who already uses the wheel engines?
Despite everything, several manufacturers believe in wheezers but, we will see it, in targeted applications. Very targeted even should we say.
Renault, for example, uses this technology in its R5. Not that of standard, but the R5 Turbo 3rd, an ultra-sporting model limited to 1,980 copies and with two rear motors. Each engine develops 278 horsepower, for a cumulative power of 555 horsepower, all in 20 -inch rims necessary to house these engines to say the least. Renault highlights “Immediate responsiveness” et “An ability to dose the power precisely to make drifts”. But it is above all a showcase product, proof is with its limited production.
Hyundai, for its part, is developing the Uni Wheel project, a range of wheat engines intended for vehicles ranging from city car to the sports model, with the ambition to release interior space and rationalize the architecture of electric platforms.
On the utility side, companies like Neapco and Elaphe are joining forces to offer robe engines designed for delivery vehicles. The space gain could make it possible to increase the loading volume, an advantage in the city centers where the place is limited. Their superb model even incorporates a two -speed gearbox, and can be mounted on conventional rims.
Protean Electric, a British company, pushes technology even further with its fifth generation of Proteandrive engines, which can equip vehicles up to 5.2 tonnes. Each 138 horsepower engine can be mounted in 18 -inch wheels, allowing a four -wheel drive configuration reaching 552 horsepower in total.
In the same vein, the rimac nevera of 1,914 hp is equipped with four engines on the wheel, as are the Lotus Evija and its 2,000 hp or the Pininfarina Battista. Three excluded supercars sold several million euros and whose architecture allows you to have absolutely extraordinary lines, all with breathtaking performance.
A false promise of simplicity?
As you may have noticed, the paradox of wheezers is striking: in theory, they simplify the vehicle by eliminating a number of mechanical components; In practice, they introduce a series of new technical and security constraints.
This observation undoubtedly explains why, despite the promising prototypes and the spectacular concepts, No high series model has yet adopted them sustainable.
Certain projects such as the Lordstown Endurance (an American electric pick-up with very disappointing autonomy, editor’s note), equipped with four robe engines, almost succeeded, but the industrial and financial difficulties ended the adventure before series production. Maybe he was just too early on his time, like many others before him.
However, the robe engines have imposed themselves in the universe of two-wheelers, including electric bikes and scooters. Their use in lunar rovers also proves their robustness in extreme environments. But for passenger cars or utilities, their adoption is still marginal.
This could change if an actor decided to take the plunge and overcome the technical challenges by suitable engineering. The constant progress in power electronics, in composite materials and cooling could raise the last locks.
The vehicles of the future could finally integrate this old idea of Ferdinand Porsche and offer a truly modular, spacious, efficient and eco-efficiency platform.
But for the moment, we are not there yet, and manufacturers’ investments seem to focus on autonomies and charging powersone of the main brakes, with prices, of the electric car today for many customers.
