Recently, at the ignition ceremony of Chery's new 2.0L displacement hybrid engine, it was clearly introduced that in addition to the hard off-road vehicle that will be installed in Jietu for the first time next year, the model will also be configured on the new car positioned at the million-level level in the future. Even if turbocharging is installed, the 2.0L displacement engine can still support the million-dollar positioning? Chery, which has always been good at engine technology, can it still bring a classic internal combustion engine in the context of hybrid?
Just looking at the range extension and plug-in hybrid, 2.0T is already considered a large displacement
Cars equipped with internal combustion engines have been developed for 100 years, but in fact, it is only in recent years that the displacement of engines has become "regularized". This is the 1.5-liter and 2.0-liter displacement as the absolute core power unit. Whether it's Ford's 1.0T, Toyota's 1.2T, Mercedes-Benz's 1.3T, Volkswagen's 1.4T, PSA's 1.6T, Audi's 1.8T. They are either completely discarded or remain unupdated for a long time. The most common is to be replaced by its own 1.5T and 2.0T engine combinations. Even if it is further compatible, you can remove the turbo and replace it with naturally aspirated. As for upward compatibility, it is not too easy to convert an equivalent 0.5L four-cylinder into a 3.0L in-line six-cylinder. To put it simply, it is to keep the cost of manufacturing a single cylinder as low as possible. In this process, if the 1.5T is a three-cylinder, it is even more ideal. It's just that this solution is not accepted by the market.
Back to Chery, in the era of fuel vehicles, there is a feeling that 1.6T is the world. As a representative of Chery's third-generation aircraft, the F4J16 engine has a maximum power of 145kW, which is indeed at the level of A+ to B-class cars. But Chery later also launched the F4J20, which is more defined as a 3.5-generation 2.0T engine. In addition to responding to the upward demand of the brand, on the other hand, it is also because Chery has broken through the constraints of the gearbox. Especially after the transverse 8AT gearbox landed, Chery launched the 2.0T on a large scale, and there was no technical constraint.
At present, the fifth-generation engine with plug-in hybrid and range extension as the development direction, Chery obviously followed the mainstream direction and chose the 1.5T+2.0T playing method. On this basis, if Chery still wants to break through the six-cylinder, then there is a high probability that it will also choose the in-line six-cylinder in the technical direction. But then again, even if Chery builds a straight-six engine, will it be able to make the more expensive Chery fuel car accepted by the market? Or to make it clearer, can the six-cylinder Chery fuel car be sold for 1 million yuan? The answer to this question is obviously not as high as the probability of taking the new energy technology route, after all, the latter already has a real case to refer to. In the field of engines, Chery, which is good at, we can also temporarily put aside the discussion of the six-cylinder engine and see what kind of technical moat this new 2.0T engine can bring.
How can the engine eat less and go far
Compared with the era of fuel vehicles, the displacement of million-dollar luxury cars is often 3.0T, and 2.0T is balanced. However, relative to the scope of the audience and the degree of application, 2.0T is undoubtedly a product of advanced technology and stability. Especially after the change of working conditions and environment, in the face of the functional needs mainly based on power generation, Chery's fifth-generation 2.0T engine has obviously become more radical than the third-generation engine that we are more familiar with.
From the perspective of bore and stroke, the third-generation Chery 1.6T engine, which we are most familiar with, has a bore of 77mm and a stroke of 85.8mm. To put it simply, this engine retains the bore of Chery's previous 1.5T engine, and then lengthens the stroke. However, this bore-stroke ratio can only be regarded as average, because the third-generation 2.0T engine launched later directly increased the bore-to-stroke ratio to the level of 1.22. Extrapolating back from this data, Chery's third-generation 2.0T engine has definitely increased its bore, but the proportion of longer strokes is even higher. The fifth-generation H4J15 engine, with a displacement of 1.5T, has a bore of 72mm and a stroke of 92mm, and the proportion has exceeded 1.27. Obviously, this H4J20 engine of the same origin will at least retain this bore stroke ratio, or even further increase it.
This is actually easy to understand, because under the trend of hybridization, the thermal efficiency requirements of internal combustion engines are further raised. In order to achieve higher thermal efficiency, it is necessary to flexibly deploy the intake and exhaust systems to achieve a greater expansion ratio. In the case of turbocharged engines, the direction of adjustment can only be the intake section, that is, the intake valve is closed early. The core logic of the whole structure is to make the piston go longer through inertia. Make more use of inertia, which is what Chery called the "deep Miller cycle" when introducing the fifth-generation engine. That is, the intake valve closes a little earlier. In addition to reducing the friction coefficient of the cylinder wall, it is also necessary to lay a longer path to lay a good foundation, that is, to lengthen the stroke. This technical requirement is destined to change the engine to a more slender cylinder shape.
But this also poses new problems, because an excessively slender cylinder block means a narrow and deep combustion chamber. On the one hand, this makes it more difficult to jet oil and gas mixtures. For example, it is easier to spray the cylinder wall, which is more likely to form irregular ignition, which eventually causes carbon deposits. On the other hand, it becomes more difficult to ignite the gas mixture in the combustion chamber more evenly and efficiently. Because the end of the combustion chamber is farther away from the spark plug.
As early as the third-generation 1.6T engine, Chery has accumulated a relatively mature fish belly inlet technology, and improved the tumbling design of the combustion chamber for oil and gas mixtures. But as the engine travel continues to lengthen, Chery also needs new technology, and this time the solution is pre-combustion.
Supercar technology can be decentralized, because the engine is mainly used to generate electricity
Pre-combustion technology is one of the lean combustion categories, with the goal of burning more fully with less fuel. However, at the specific implementation level, some car companies choose to use the existing combustion chamber to achieve the effect of igniting a small number and then igniting the entire combustion chamber, which is represented by Mazda's compression-ignition engine. Another route is to design an additional auxiliary combustion chamber, and the oil-gas mixture ignited first in this area will ignite the lean oil-gas mixture in the main combustion chamber. The masterpiece of this route is the Maserati Poseidon engine, which of course can be traced back to the engines of today's Formula 1 cars.
However, even the technical scheme of the pre-combustion chamber has different details. In theory, the twin combustion chambers should be independently equipped with oil supply, gas, and ignition systems. But in a high-volume operation, this design is too complex and takes up too much space. Even Maserati, on the Poseidon engine, retains only one oil supply system. The oil-gas mixture is then pressed into the pre-combustion chamber by adjusting the timing of the injection and by means of piston diversion guidance. This can also be counted as passive pre-combustion technology. The advantage is not only that the oil supply system is eliminated, but also that the main combustion chamber can reduce the burden on the usual cycle at low loads. Because the main combustion chamber of the Poseidon engine retains a complete set of oil supply and ignition systems.
Chery, on the other hand, chose the active pre-combustion solution, which is equipped with a complete oil, gas and ignition system in the pre-combustion chamber. As for the main combustion chamber, we can see from the relevant patent drawings that there is only one air intake, and there is no display of additional spark plugs. The reason is that the fifth-generation H4J20 engine is aimed at plug-in hybrid PHEVs and extended-range REEVs, and there is no compatibility requirement under low-load conditions at all. At the same time, this greatly reduces the calibration pressure after the application of pre-combustion chamber technology, and additionally provides the stability of the implementation of new technologies.
It is worth mentioning that the pre-combustion chamber also has the effect of reducing engine knocking. Combined with the fact that Chery did not explicitly introduce 500Bar high-pressure direct injection on the fifth-generation engine. Its direct injection pressure is likely to remain at the current mainstream level of 350Bar. Therefore, the 2.0T engine developed for plug-in hybrid and extended range is likely to continue to be compatible with lower grades of gasoline.
In short, the core appeal of Chery's new 2.0T engine is to use less gasoline and generate more electricity. To this end, we have not hesitated to excavate pre-combustion chamber technology, which is often used in supercars. Dramatically, this operation allows it to shoulder the direct drive under high load conditions even in the PHEV state. Obviously, more efficient engines can continue to endorse million-dollar products under the wave of new energy.