How does this strange hybrid system work?

Not all hybrids are created equal. In particular, the Nissan Qashqai, which is opening its electronic power technology in Europe.

For many technical, financial, or strategic reasons, not all car manufacturers use the same mechanical configurations for their electrified engines. This is especially the case with mixed solutions, where there are many configurations. One of the intriguing things comes to us again from Japan: electronic power technology is the technology closest to electric propulsion ideologically. explanations.

Behind this new name in Europe hides a mechanism that cut its teeth in Japan with the Nissan Note e-Power, giving it a second chance at life: it became the best-selling car in the archipelago (with the exception of indestructible kei cars) with a very large majority of e-Power engines. navel? An almost unique configuration, in which only an electric motor drives the wheels, while a heat engine acts only as a generator of electricity. A system similar to that of Fisker Karma or BMW i3 REx. Or even the Voltec solution of the first-generation Opel Ampera, although the manufacturer failed to indicate that the heat engine actually had contact with the wheels at times.

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In Japan, the discourse is well established: this will offer all the advantagesElectrical engine Lots of promotion by Nissan, while eliminating its drawbacks. To better underscore its philosophy, the Note borrowed several elements from the Nissan Leaf, such as the engine, a piece of battery, the front/rear gear selector, or even the electronic pedal system. It then benefited from the approval and immediacy of a small electrician, while offering autonomy within the confines of a petrol tank. In usage, it’s hard to tell the difference with the classic hybrid, especially since the ingredients weren’t sized well or optimized. But water has been flowing under the bridge since 2017, and electronic power technology has introduced a much-needed technical update for Europe.

The principle is always the same: the electric motor installed in the front is powered by the battery, which itself is recharged by the internal combustion engine. This is the basic principle of the so-called hybrid sequential process. So it differs from Toyota’s parallel hybrid system and we find similar operation on Mitsubishi or on Honda e:HEV technology (formerly i-MMD). In the latter cases, a sequential hybrid mode is possible depending on certain driving stages, but the internal combustion engine can still drive the wheels at high speed, where the electric motor is not the most efficient.

What the e-Power does not do, which, in the order of the power supply chain, consists of a heat engine, alternator (Nissan does not call it an electric motor like Honda), battery, commutator and inverter. Electrical engine. Thus, the fixed configuration develops a total power of 190 hp (140 kW) for a torque of 330 Nm, and is available with all drive modes. Therefore, the values ​​of the electric motor are inherent in the technical sheet.

Unique motor with variable compression ratio

Contrary to all expectations, the focus of this scheme is thermomechanics, which differs significantly from the modest HRD12DE of the eponymous note (which still continues its career with the new generation of the city car). Because if the power of this unit does not matter for moving the car forward, and not really for the production of power in a small car, then Nissan had to deeply review its version for application in SUVs and to meet European standards.

The thermal generator is a 3-cylinder 1.5-liter, with a power of 158 hp (116 kW) and a torque of 250 Nm. The engine is small, no doubt, limited by CO2 emissions rules, but also by the space available in the bay, where it is installed longitudinally. The MR15DDT (DOHC, Direct Injection, Turbo) with the abbreviation VCR is the second to use a variable compression ratio as standard, the first being introduced for Infiniti in the United States. Its goal is to measure compression ratios as needed, with ratios ranging from 8:1 to 14:1 here. To achieve this, Nissan engineers developed a system that increases or decreases piston stroke via an actuator depending on power demand. So the technical solution is quite similar to that of the VC-T engine, which was found for example in the Infiniti QX50 for example.

In most cases, when the power demand is reasonable, the engine prefers a high compression ratio, which ensures efficiency and reduces emissions. On the contrary, a lower compression ratio enhances the power. In both cases, the injection technique is quite traditional because it is a homogeneous, not stratified, direct injection. Also, a rotational speed of 4800 rpm is most often maintained, during which the peak torque of the engine is reached. But the system can change the speed according to the power needs, but also so that there is no difference between the engine speed and the speed.

Because that’s one of the criticisms we have for this type of hybrid system, where the engine tends to roar much louder than the car moves forward. A feeling quite similar to what a Toyota hybrid mechanism can provide due to the planetary transmission. But e-Power technology features an electric motor that still delivers responsiveness, when the HSD system gives the impression of energy wasting in the air. But to enhance the experience even more, Nissan engineers developed the device line melody Which the number of revolutions varies based on throttle pressure and speed, although it is not strictly necessary to do so. A solution that turned out to be more interesting than the wrong gearshifts that appear more and more on mechanics without gearboxes (Ford Kuga Hybrid, Honda Civic e: HEV, etc.).

The motor is directly connected to an electric generator that produces 110 kW of power. It takes care of recharging the battery installed under the front seats, when it reaches its minimum charge. It also directly supports the battery during heavy loads to fill the power gap. Since the battery has a net capacity of 1.97 kWh (2.1 kWh total) it can only produce a maximum of 60 kWh (80 hp), which is a much lower power level than the 140 kWh (190 hp) that the machine can take advantage of. electrical. Note that the battery is based on 96 cells and powered by 346V, is obviously not rechargeable by an external power source and has operating thresholds between 25 and 75% of the SoC. This allows to keep to a minimum the buffer necessary to ensure correct operation of the system (although it can technically do this), but also to not see performance crash at low load.

electric with exhaust

The question of the overall efficiency of this engine always arises in the face of these many brokers. Cependant, Nissan n’a pas été en mesure de nous fournir l’information for le moment, mais de préciser que le bloc thermique peut présenter un taux de 38% en moyenne, avec un rendement thermodynamique proche des 40% avec le taux de compression higher. In the end, it is very close to the atmospheric mechanics of the Atkinson cycle (Toyota or Honda), which managed to deliver record values ​​\u200b\u200bof 41%.

With larger components and much more detailed technology than noted on the note, the electronic power system should live up to the level of the Nissan Qashqai, which opens the mechanics in Europe. That’s what its CMF-CD platform allows, while the Juke Hybrid (CMF-B) platform has no choice but to use Renault’s e-Tech solution. However, if the principle wants above all to put a fileelectric motor feeling, the system is as close to conventional on-wheel hybrid mechanics than to alternator-supported electromechanics as observation can offer. An important nuance.

When it arrives in Europe, the system is offered completely differently by Nissan so as not to bother customers. Because when the technology came to Japan, Yokohama liked to say that the motors took advantage of all the benefits of electric propulsion without having to worry about recharging. But one zero-emission sign voluntarily forgot to point out that one of the main advantages of electric motors is precisely that they do not emit carbon dioxide. What the electronic power solution does not do.

On WLTP-certified seats, the Nissan Qashqai e-Power displays consumption from 5.3 to 5.4 l/100 km (119-123 g/km CO2) depending on configurations. The goal appears successful on the board. To put it in perspective, the Toyota CH-R 2.0-liter Hybrid is offered with 184 hp in total sails between 5.2 and 5.3 l/100 km (118-121 g/km), and the RAV4, in its top class, is between 5.6 and 5.8 l / 100 km (126-132 g / km) with a capacity of 2.5 liters with a total power of 218 hp.

Transitional Hybrid for Nissan

There are two ways to look at things when it comes to electricity. Strictly speaking about fuel, the Qashqai is a hybrid because gasoline is necessary to run it. But things are different under the hood. But the e-Power isn’t really a hybrid (the heat engine doesn’t directly contribute to wheel spin), and its electric motor alone doesn’t make it an electric car: let’s not forget that the Qashqai has an exhaust port.

Regardless of which philosophical approach one may take, the Nissan Qashqai e-Power will indeed have a mixed gray card, with the abbreviation EH in box P.3. So he wouldn’t benefit from any environmental reward or penalty for now. A respite that Nissan intends to take advantage of, which sees its engine as a transitional solution to all-electric, more relevant to plug-in hybrid solutions. Look to our tester soon to see if it can deliver on its promises.

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