New engine technology: VCM automatically switches the variable cylinder fuel consumption by 8%
When oil prices continue to hit new highs, and car manufacturers around the world are striving to develop new energy vehicles for the future, the most realistic thing is to upgrade the traditional gasoline (diesel) technology to achieve more fuel-efficient effects. In-cylinder direct injection, lean combustion, VVT and other technologies have appeared, but the purpose is to make the engine more fully burned; but there is another way to save fuel - directly shutting off the excess cylinders in the work, this is theoretically simple The effective fuel-saving method has become more feasible with the continuous improvement of engine management technology, and has gradually been favored by major car manufacturers.
We know that a large-displacement multi-cylinder engine can bring more power reserves to meet the needs of high-speed rushing, rapid acceleration and climbing, but large displacement will naturally lead to high fuel consumption, especially in the city. When you walk away and don't need strong power, the large displacement engine is a waste. The most thorough solution to the problem is hybrid power, but the cost is not small, and the application of fuel-saving technologies such as turbocharging, in-cylinder direct injection and lean combustion is an effective method.
The Honda Accord 3.5L V6 engine uses the new VCM technology, which can generate 280 horsepower and low fuel consumption (90km/h is only 6.8L/100km). VCM is a variable cylinder management technology. Great contribution. When VCM began to become the focus of attention, it was quickly discovered that this technology was not unique to Honda, and it was already applied to Shanghai GM LaCrosse 3.0 and Chrysler 300C early on, and the application of this variable cylinder management technology can be traced back to 1980s. However, the true meaning of Honda VCM is not only to further apply the V8, V12 variable cylinder management technology, but also to apply it to the popular V6 engine reliably and efficiently, and to work with Honda VTEC. The technology is more advanced.
GM's earliest application of variable cylinder technology
Luxury cars usually have multi-cylinder large displacement engines with V6, V8, V10 and even V12, especially in the United States, Germany and the United Kingdom. However, in daily driving, in most cases, high-power output is not required, and large-displacement multi-cylinders are a bit wasteful. In the 1980s, GM used the new cast aluminum cylinder head HT-4100 V8 engine in the second generation Cadillac Seville. This engine became the world's first VDE engine. When high power output is required, half of the cylinders can be controlled to reduce fuel consumption.
Although the variable cylinder technology is theoretically very attractive, it is limited by the backward computer technology at that time, unable to complete 200 operations per second, some engines even have to be controlled by mechanical means, so not only the fuel saving effect is not obvious, but also It also brings reliability issues. Usually, loud noise is generated. For example, the process of converting from 8 to 4 cylinders is very unstable, and occasionally it is stuck in one state and cannot be adjusted. As a result, this variable cylinder technology quietly retreated from the front line and was refrigerated with a beautiful concept.
More than 20 years have passed, thanks to the rapid development of on-board computer technology, the current on-board computer chip can reach 2000 times per second, so the variable cylinder management technology can be revived. In 2005, Shanghai GM launched the new LaCrosse sedan. The top version is equipped with an AFM V6 3.0L engine. The AFM is translated as “smart fuel management systemâ€. The highlight of this engine is the use of advanced DOD (Displacement on Demand). Displacement control technology. When the engine load is small, the DOD will issue an instruction to close three of the cylinders for fuel saving purposes. The LaCrosse's DOD technology not only saves up to 8% of fuel consumption, but also makes the cylinders switch smoothly, with no vibration at all, which the driver can't feel.
Honda VCM technology goes one step further
The traditional variable cylinder technology is only applied to multi-cylinder engines such as V8 and V12, and generally only closes the number of cylinders. However, the VCM technology developed by Honda can change the individual cylinders so that the 3.5L V6 engine can be changed between 3, 4, and 6 cylinders, so that the engine displacement can also vary between 1.75 and 3.5L. Great savings in fuel. The working process of VCM is as follows:
When the engine is cold, VCM will put all six cylinders into operation, in order to achieve the best working temperature for all cylinders. Once the engine warm-up work is completed, VCM will collect the current vehicle speed, throttle change range, oil temperature, gearbox working status and other information according to the sensors distributed throughout the vehicle to determine the working state of the cylinder. If the vehicle is in a state of rapid acceleration, climbing and high-speed driving, which requires a strong power output, the engine will keep 6 cylinders working. In fact, there are not many opportunities for all six cylinders to work.
More often, when the vehicle is cruising on the highway, moderately accelerating, and entering a gentle slope, the VCM will close the cylinder in the middle of each of the three cylinders in the column around the V6 engine, so that the engine will handle four cylinders. After closing some of the cylinders, the VCM will continue to operate the non-operating cylinders, and the spark plugs continue to ignite, so that all cylinders are evenly worn. The temperature of the spark plugs is maintained so that the cylinders can enter the work at any time.
When the vehicle enters the city for slow driving, idling, or low-load driving, the VCM closes the three cylinders on one side, so that the engine only runs with the other three cylinders, and the actual displacement is only equivalent to 1.75L.
Technical advantages of VCM
Honda's VCM technology is clearly more mature, thanks to Honda's many years of i-VTEC technology. Simply adding some new design to the VTEC mechanical structure makes it easy to change the timing of the valve while closing the cylinder, not only to make the working cylinders more efficient, but also to stop being shut down. The intake and exhaust of the cylinder.
Guangzhou Honda's eighth-generation Accord 3.5L is the first to use VCM technology. The actual test drive Accord 3.5L, this Accord has the largest displacement in history, the most powerful engine performance is very smooth, the idle speed is very quiet, and the high speed is Can give off a strong momentum. If there isn't an "ECO" light on the dashboard that lights up from time to time, we don't even know when the VCM system is involved. When idling and easing, the ECO light will remain on. At this time, the engine may work in a 3-cylinder or 4-cylinder state. If the throttle is deeply stepped on, the ECO light will be extinguished immediately, and the engine will work in 6 cylinders, and the power will continue to flow. If the throttle is released for 1-3 seconds while driving, the ECO light will immediately illuminate, indicating that the engine has entered the closed cylinder operating state. But no matter how VCM changes, we don't feel a trace of vibration when the cylinder is switched. This system is just as fun as a hybrid engine, and the actual performance is well-deserved. The half-day driving down the oil gauge pointer is significantly lower than the average 3.5L V6. The engine is small, and VCM does have a fuel-efficient effect. But while fuel-efficient, we found that the engine output was milder and lacked explosive power, apparently at the expense of some high performance for fuel economy.
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