Text/Civil
We will find a problem when comparing car parameters, the engine power on the hybrid model is generally lower than that of the same displacement of fuel models, such as the Toyota Fenglanda 2.0L engine, the maximum 126kW power, 171 horsepower, and the Honda CR-V hybrid version, 2.0L engine maximum 107kW power, 146 horsepower. Is it a manufacturer technical difference? Or is it to reduce costs?
Obviously, none of them, the reason why the engine power of the hybrid model is lower than that of the same displacement fuel vehicle is because the combustion cycle of the engine they use is different. Engines generally focus on only one in terms of economy and power, which is difficult to take into account.
At present, the four-stroke internal combustion engine commonly used in fuel models on the market uses the Otto cycle, which has the advantage of low technical difficulty; while the positioning of the hybrid model is fuel economy, so it is usually matched with the Atkinson cycle engine (or Miller cycle), or the Atkinson cycle and the Otto cycle can be seamlessly connected to the engine. Their advantages are high efficiency and fuel saving.
What is the difference between the three and how to distinguish them?
Otto cycle, simply put, this engine has four stages of suction, compression, work, and exhaust, and the travel of the piston in these four stages is the same. The compression ratio of the Otto cycle is equal to the expansion ratio, and the structure is simple and does not require a complex gas distribution mechanism.
The essence of the Atkinson cycle is that the expansion ratio is greater than the compression ratio. The method of delaying the valve closing time is used to allow the gas mixture in the cylinder to be pressed back into the intake pipe part, so that the work stroke of the piston is greater than the compression stroke. Therefore, the benefit of the Atkinson cycle is that the engine is more efficient, that is, the thermal efficiency is higher. The price is sacrificing motivation.
The Miller cycle is actually similar to Atkinson, and the expansion ratio is greater than the compression ratio, but in a different way. Miller cycles are achieved by closing the valves early, before the end of the intake stroke. Compared to the Atkinson cycle, such an approach is more fuel-efficient at low loads, but at high loads it can lead to insufficient engine power.
Both atkinson and miller cycles are designed to save fuel and reduce emissions without compromising engine performance. But the disadvantage is obvious, that is, the motivation will decrease. General car companies will make a complex gas distribution mechanism for the Atkinson and Miller cycles to make up for the shortcomings of these two cycles.
How are atkinson and Miller cycles applied and performed in practice?
Back to the original problem, the reason why the engine power of the hybrid model is lower than that of the fuel model is that the nominal displacement of the engine is the displacement of the working stroke, and the calculation of the power level should be calculated by the displacement of the compression stroke, so if the Atkinson and Miller cycle engines are 2.0L displacement, the actual power will be smaller than the 2.0L of the Otto cycle, which may be similar to the 1.8L Otto cycle engine power.
However, the engine on the general hybrid model will only directly drive the car under the conditions of great need for power or suitable for the efficient operation of the engine, and the efficiency of the engine is low in most working conditions, so the main role of the engine is to drive the generator to generate electricity, and the main power to drive the car is the motor.
In terms of specific applications, such as the Atkinson cycle 1.8L engine in the Toyota hybrid system, the maximum horsepower is less than 100 horses, but the fuel consumption is only 3L; Honda's Ten Generation Civic, Alto cycle 1.5T engine, the maximum power is close to 200 horses, while the fuel consumption needs to be more than doubled, so as the ultimate goal of the hybrid, the engine of the Atkinson and Miller cycles with lower power but good fuel consumption performance is the first choice.
summary:
The fundamental reason why the engine power of the hybrid model is lower than that of the same displacement fuel vehicle is because all the purposes of the hybrid model are for fuel economy, and the more powerful Otto cycle engine cannot meet this condition, and the advantage of the Atkinson and Miller cycle engines is that the thermal efficiency is higher, the fuel saving effect is obvious, although it will lead to insufficient power but can be solved by the motor. So there is no need to worry about the size of the power.