For consumers, in fact, buying a car depends on three factors. One is the power of the vehicle, which determines the strength of the driver to move forward quickly and enter the cabin. One is handling, which determines whether the steering of the vehicle is accurate enough and the chassis support is sufficient during intense driving. There is also fuel economy, which determines the fuel consumption of the vehicle and also affects the thickness of the owner's wallet. It can be said that through a simple analysis, it is not difficult to see that consumers who buy cars now pay more attention to the third one, which is fuel economy, followed by power and handling, so the ranking between them It's like this, fuel economy>power>maneuverability. Precisely because of such user needs and consumer psychology portraits, car companies and engineers continue to make efforts in these fields, and the most important thing to say is that it is the most important component of the car, the engine technology.
Presumably everyone knows that when the engine consumes fuel, work needs to be done. We have already learned this in the physics textbook of junior high school. The engine workmanship is also divided into four major strokes, which are intake stroke, compression stroke, power stroke and exhaust stroke. Each time the engine completes these four steps, it is called a cycle. This kind of cycle currently has three optimization techniques, they are Atkinson cycle, Miller cycle, Otto cycle, so today we are talking about this Miller cycle, it is also currently done on the four-stroke technology The best cycle mode that combines fuel economy and power. Let's take a look at it in detail.
What is Miller Cycle?
uses a supercharged Miller cycle Mazda 2.3S engine
First of all, we need to know what a Miller cycle engine is, In fact, to put it plainly, the Miller cycle engine is a supercharger four-stroke engine based on the Otto cycle. It was first patented by American mechanical engineer Ralph Miller in the 1940s, but it was not until the 1990s that Japan’s Mazda applied it to its large touring car series Millenia. This engine design Only then began to be widely known.
This engine is equipped on mazda Millenia
What is the working principle?
As we mentioned earlier, the general working principle of the Otto cycle engine is basic intake (mixed fuel and air are injected into the cylinder by one or more intake valves), compression (mixed fuel and air Compressed), ignition (the mixed fuel and air are ignited by a spark plug near the apex of the compression stroke), exhaust (combusted exhaust gas is discharged from the cylinder by one or more exhaust valves). Due to the structure Simple, low fuel and exhaust gas utilization, so it will gradually be eliminated by the market.
The Miller cycle is different. It moves the piston to bottom dead center during the intake stroke, but the intake valve remains open while the piston is compressed. The intake valve does not close until the crankshaft passes 70 degrees after the bottom dead center of the piston. To put it simply, in the compression stroke, the intake valve is delayed first, and the intake valve is completely closed when the piston rises about two-fifths of the volume in the cylinder. Therefore, some of the gas in the cylinder will re-enter the intake manifold and maintain the air pressure under the action of supercharging. Therefore, the intake efficiency can be improved and the pump pressure loss can be reduced during the next intake stroke. However, this also causes the actual compressed air to be no more than when it is taken in, which reduces the compression ratio. However, during the ignition stroke, the piston still moves from the top dead center to the bottom dead center, resulting in a special situation where the expansion ratio is greater than the compression ratio. The compression is relatively small, so the fuel consumption is low, and the expansion ratio is large, so the power is large. On the other hand, it also prevents the engine from knocking (pre-ignition) caused by the excessive compression ratio.
To put it simply, the Miller cycle engine abandons the traditional complex connecting rod structure, and instead uses the timing of the gas to create this effect. The solution is: at the end of the intake stroke, postpone the closing of the valve, which will "spit out" part of the inhaled mixture, then close the valve and start the compression stroke. Such a simple control of the timing of opening and closing of a valve creates the effect that the expansion ratio is greater than the compression ratio. Therefore, compared with the traditional Otto cycle engine, the energy contained in the exhaust gas can be fully utilized again, which is why car companies like it now One of the reasons for using the Miller cycle engine.
Of course, Miller cycle and Atkinson cycle engines are actually widely used, so no matter which cycle it is, it is to make the engine burn better. As for the usage habits, the Atkinson cycle is generally used by Japanese car companies, while German cars prefer Miller. Volkswagen's EA211 TSI evo engine and EA888 TSI engine all use the Miller cycle. Compared with the other two cycles, the Otto cycle is not high in hard-core technology, so it is also the most widely used in car companies, mostly in some entry-level models.
Which car models use Miller cycle technology?
The advantages and disadvantages of the Miller cycle are described in detail above. So which models on the market currently use the Miller cycle technology? The following brother will focus on introducing a few models to everyone.
JMC Ford Territory
Engine: JX4G15C6L series direct injection 1.5T
as a joint venture compact SUV, leading The space in the world is still very good, and the configuration is also rich, and the materials used are more kind. From the perspective of comprehensive pricing, overall it is more recommended.
In terms of power, thanks to the blessing of Miller cycle technology, the compression ratio of the 1.5T engine equipped in the Territory has increased from 9.5 to 11.4, and the thermal efficiency has increased from 36 % Increased to 37.5%, which increases the expansion ratio of the engine to a greater extent, and also greatly reduces the fuel consumption of the vehicle in urban conditions, and the result is naturally more fuel-efficient. Therefore, it can be said that Ford's territorial technology has brought tangible benefits to consumers, so this car master thinks it is worthwhile to start. After all, the price is not expensive, only 10.98-16.88 million, right?
Dongfeng Nissan Qashqai
Engine: HRA2 series direct injection 1.2T
The appearance of the cash Qashqai really makes people change after a small change It feels bright, and this is also the main reason why this type of compact SUV that focuses on youthfulness is so attractive, and that is because of the existence of good looks. Of course, the Qashqai's handling is also impressive. The chassis is tuned enough and the body roll control is relatively slight. Facing corners, there is no sense of restlessness caused by the high center of gravity of the SUV model. The performance is worthy of the identity of a joint venture SUV.
And in terms of power, although its 1.2T engine has a relatively average acceleration performance, it is still sufficient for daily use. This 1.2T engine also uses Miller cycle and direct injection technology. Technically speaking, it is jointly developed by Nissan and Renault, and it also adds a self-start-stop function. Turbocharger can output the maximum torque at a very low speed. In addition, the engine speed is about 1500 rpm under normal road conditions, so ordinary familiesTraveling with a full load is actually no problem at all. The performance in terms of fuel consumption is also very good. The average fuel consumption is 6.9L-8.3L, which is a very low level. Of course, this is also due to the role played by the Miller cycle.
SAIC Volkswagen Tuyue
Engine: EA211-DJS-CSS series direct injection 1.4T, EA888-DKV series direct injection 2.0T
As the fresh blood invested by SAIC Volkswagen in the compact SUV market, Tuyue is expected to take over the old Tiguan flag. The overall performance of the vehicle is relatively balanced, and Volkswagen’s brand appeal is also destined to become a model. Very popular models. From the appearance point of view, Tuyue as a whole is very in line with the appetite of today's young consumers, and it is more tough than previous Volkswagen models.
The power performance is also very good, the 2.0T measured acceleration is 7.33 seconds, and the dual-clutch transmission is also very tacit in daily driving. Like our theme today, Volkswagen Tuyue is also the first domestic model to be equipped with both Miller cycle and turbocharging. The engine has a dual-injection calculation system, which is more powerful and fuel-efficient than the traditional EA888 engine. Therefore, consumers can buy a Tuyue with a price of more than 200,000 yuan. I think the overall performance is quite worth it, and the product performance is also very good.
Finally, after reading the Miller cycle principle and model recommendation introduced by Brother today, I wonder if you have any Increase knowledge? In fact, the emergence of new technologies is not only to provide consumers with more economical and practical model choices, but also a gimmick provided by the manufacturers themselves in order to make the models sell at a good price. Although technology is indeed the primary productive force, we should not blindly believe in everything. Laser welding and cavity wax injection promoted by the public in the early two years are actually just a common technical method in automobile production, and it is not enough. In order to become a selling point, we consumers need to be more rational when buying cars.
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