Finding: Advantages and Disadvantages of Automatic Start and Stop of Engines

With the increasingly stringent environmental protection requirements, energy-saving and emission-reduction become a factor that cars are increasingly valued. More and more automobiles are equipped with automatic engine start-stop technology. This technology is particularly suitable for urban road conditions, when the engine is temporarily turned off while waiting for a red light, it can save fuel consumption at idle. As with all new technologies being fitted to the product, the engine's automatic start-stop technology also faces many questions. Can it really save energy and reduce emissions, contribute to environmental protection, save fuel for owners, stop and stop the road, is there any damage to the engine?

Automatic start and stop of engine
Advantages and disadvantages of starting and stopping the engine automatically

What is the engine automatic start and stop technology

Literally, it is a system that can automatically control the engine flameout and ignition. The English name is STOP&START, abbreviated to STT. Vehicles equipped with an automatic engine start-stop technology will automatically shut off when temporarily stopping during driving. When you need to continue to move forward, the system will automatically restart the engine.

Its core lies in the automatic control of flameout and start-up. It can minimize engine idling idle time to reduce unnecessary fuel consumption, reduce emissions and improve fuel economy. In order to ensure the comfort of the passengers, after the engine stalls, the battery will replace the pulleys to provide the operating power for the engine cooling fan and the interior air conditioning.

The principle of automatic engine start-stop technology

To understand whether the engine start-stop technology is harmful to the car, we must start with its principle.

When the vehicle stops traveling due to congestion, the driver depresses the brake pedal and removes the gear, and the vehicle is stationary. At this time, the automatic start-stop system starts self-checking. When it finds that the engine is spinning and there is no gear, the wheel speed sensor reads zero, and it continues to check if the vehicle has enough power to start the next time. When the above conditions are met, the engine will automatically stop working. After a while, you have to go, so you release the brakes, step on the accelerator pedal, and the engine will start to reignite again.

The idea of ​​engine start-stop technology emerged as early as the 1930s, and the application of the car dates back to the 1970s. At that time, Toyota had conducted similar tests on the Crown sedans. When the vehicle stopped for 1.5 seconds, the engine would automatically shut off the fuel and cut off the flame. This could be said to be the prototype of the engine's automatic start-stop technology. In the 1980s, Volkswagen and Fiat produced their cars in production, but it wasn’t until 2006 that automatic start-stop technology became available.

Why do we need to use the engine automatic start and stop technology?

Putting aside environmental protection, energy conservation and emission reductions, the most direct reason why we use automatic start and stop is to save money.

Many people believe that turning off/starting frequently in urban roads will increase the fuel consumption and will not achieve the purpose of saving fuel. This is not the case. When the vehicle restarts after a short stop, the starting resistance is small because the engine is at normal operating temperature. At start-up, the engine flywheel is started with the help of a starter. At this time, the fuel consumption for starting is only equivalent to the fuel consumption of 0.7 seconds idle, so theoretically, the fuel-saving effect will be achieved when the vehicle is parked for more than 0.7 seconds.

If we don't turn off the engine when parking, the average fuel consumption of the 1.4T engine is about 2.7 liters/hour. We can calculate 2 liters/hour. Consuming 5.5 milliliters of idle speed for 10 seconds, and waiting for an average of 60 seconds at a traffic light, the initial fuel consumption of the planer can save 11 Coke (355 ml) of oil. In the long run, how much oil will it save?

Bosch previously conducted experiments on engine start-stop technology and concluded that the average fuel-saving rate is about 8% to 15%. The greater the congestion, the greater the effect of displacement. The China Automotive Technology and Research Center has also conducted similar tests. The result is that the fuel-saving rate reaches 7%-27%.

But what we need to know is that everything in this world is not perfect. The pros and cons of a technology exist at the same time, and manufacturers often emphasize the advantages of propaganda, but they do not even mention the shortcomings.

Does the automatic start-stop technology damage the engine?

Most friends around me also have questions about this issue. Some people think that the automatic start-stop function is best not to use, because frequent other will cause the piston to wear, the metal debris generated will also wear out other key parts of the engine. Over time, the damage to the engine is great. It sounds like that is the case, but think about it without having to worry about it.

Frequent start and stop of the engine does indeed mean that the wear of the engine is greater, but they all overlooked that the wear of the engine mostly occurs when the cold car starts. More than 80% of the wear of automotive engines comes from the moment of cold start, and normal idle running wear accounts for about 20%. The environment of automatic start-stop work is a hot start, but the engine is temporarily turned off when the vehicle is temporarily parked. At this time, the engine temperature is still high, the engine oil is less viscous, and the fluidity is relatively strong, and it easily adheres to the components. The wear will not be great at this time.

Battery and starter maintenance costs are high

Although there is not much damage to the engine, the engine start-stop technology has its drawbacks. Frequent start and stop of the engine can cause damage to related components such as starters and batteries. Although vehicles with an automatic start-stop system use enhanced starters and batteries, in practice, their failures are higher than those of ordinary vehicles that do not have an automatic start-stop system.

At the same time, enhanced starter and battery maintenance costs will be higher than ordinary starters and batteries. This raises the issue of higher maintenance costs. In addition, because the engine is repeatedly started and stopped repeatedly, this has a higher requirement on the quality of the oil, so that the maintenance costs further increase.

Poor user experience is prone to carbon deposition

Different brands of different models, automatic start and stop system design is also different. The start-stop logic of some models is not very good, and the intervention time is not accurate. Sometimes the long-term stop-start system does not act, but when it is swiped at the toll station, it is braked but it is unsolicited. In addition, noise and vibration at start-up are also a disadvantage of the rider.

In addition, if a serious traffic jam is encountered, the engine will stop working for a long time and the temperature of the combustion chamber will be reduced. Carbon dioxide and paraffin which have not been completely burnt will form carbon deposits and adhere to the inner wall of the cylinder. If the oil is not good, the situation will be more serious. Carbon deposition will increase fuel consumption and reduce power. This is an automatic start-stop function designed to reduce fuel consumption, which in turn increases fuel consumption.

to sum up:

The original intention of the engine's automatic start-stop technology design is for environmental protection and energy conservation. In the theoretical environment, it can indeed achieve this goal. However, if we combine the road conditions in our country - long traffic jams, long periods of stop-and-go will inevitably increase the burden on the starter.

Therefore, in the case of long-term congestion, it is better to turn off the automatic start-stop function, which is more conducive to extending the life of the starter and the battery. However, if the condition of the air-conditioner is open, the burden on the battery is relatively large. In order to start the next time, the engine may start at the very beginning of the stop. At this time also try not to open the automatic start and stop function.

In the case of better traffic conditions, if the red light is more (such as Chang'an Street), then the automatic start and stop function can play its role. In short, the matter is artificial, the engine start-stop technology may not be suitable for China's road conditions in practical applications, but as the technology matures, this system will eventually be widely popularized.

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