With regard to "Oil Throttle", it is time for automotive professional Xiaobian to restore the facts!

Some time ago, the automobile circle had made a lot of noises due to Honda's “throttle”, and many people even had doubts about the quality of the Honda brand. Why do you feel that the increase in oil seems to have been heard recently? There has been a period of time before the “accident of the engine”, and people have become calm. As a small editor of engineering, you will know the fact behind the increase in motor oil.

Gasoline engine changes

Said that the increase in oil, have to mention the gasoline engine technology changes in the past years, in the birth and development of gasoline engines have been using the inlet fuel injection, naturally aspirated fuel injection.

In recent years, in order to pursue a series of features such as small displacement, high power, fuel economy, and environmental protection, more and more engines have been designed as direct injection and turbocharged fuel injection methods in fuel tanks. . Does it sound like "direct injection" is a new technology for the engine? The answer is no, technically speaking, direct fuel injection technology is used in the diesel engine's "watching the home line", the initial structural design of the diesel engine is used in the direct injection cylinder.

Diesel engines have no spark plugs and instead are fuel injectors. The injectors of traditional gasoline engines are not in the cylinder, but in the intake (outside the cylinder). And we can clearly see that the oil sump and the combustion chamber are not two separate closed spaces, but there are piston gaps that connect them to each other.

Engine radon

Since there is a gap between the combustion chamber and the oil sump, first of all, it is necessary to understand that there is a bit of engine that is inherently unavoidable, either that there is oil in the oil sump to increase the oil, or that the oil enters the combustion chamber and causes the engine to burn oil. What is the increase in oil? process.

During the compression and combustion stroke, a small amount of fuel enters the crankcase (oil sump) through the gap at the piston ring, which is referred to in the industry as "helium gas."

And in the compression and combustion stroke, due to the inherent motion characteristics of the engine piston, there is always the need to fit tightly on one side and the cylinder wall, and on the other side, the pressure on the other side is small (for convenience of expression, the clearance on the drawing is slightly Exaggerated. This also increased the occurrence of radon to some extent.

Zooming in, the piston's head is equipped with a seal ring, but due to the lubrication of the piston, and taking into account the resistance of the movement, even if the piston is installed with a sealing ring, inevitably occur helium.

What's wrong with in-cylinder direct injection, turbocharged technology?

With a port injection gasoline engine, the fuel injected by the injector has been mixed with the air before entering the cylinder. The mixed fuel mixture is drawn into the cylinder through the intake stroke, because the intake speed is very fast. Together with the flow characteristics of air and inertia, combustible gas is basically in contact with the top of the piston.

The direct fuel injection technology features fuel injectors that directly inject fuel into the cylinders, but the atomized fuel also mixes with the air in the cylinder, and because of the direct injection technology used in most engines, the fog is emitted. Most of the fuel oil falls on the cylinder wall.

In the compression and combustion stroke of the piston, the piston ring on the piston head that originally provides the lubrication and sealing effect may have oil scraping phenomenon, especially in a relatively cold area, the fuel atomized by the injector during the cold start of the vehicle is also There is no time to mix with the air, and the air after passing through the air filter originally has a small amount of water vapor, which condenses after encountering a cold cylinder wall, and is then scraped into the crankcase (oil sump) by a small amount during the compression stroke. This is why The increase in the Honda CR-V oil has initially occurred in cold regions.

Coupled with the current use of turbocharging technology, the gasoline entering the crankcase during the cold start, after the engine heats up, the pressure of the intake air increases due to the intervention of the turbine, so that the engine oil that could otherwise be heated can solve the problem of increased oil. This situation is complicated by the intervention of the turbine.

Considering that every time you actually enter the crankcase with gasoline and water through helium is very small, in order to answer many people's doubts, we come to the actual calculation. The four-stroke engine rotates the crankshaft two times per crankshaft (work once). Suppose a four-cylinder engine idles at 2000 rpm during cold start. Then, the engine must be injected 4000 times per minute. In addition, the ECU will generally respond to the cold start. Spray more fuel. In particular, most people drive in short-distance. After the car is cold-started, the gasoline that has entered the crankcase has not been left hot until it is exhausted. The car is then stopped and frozen there. This way, it is easy to repeat the above-mentioned process every day. Thousands of helium gasses have been completed. Dilution of engine oil has become normal.

Is there any increase in engine oil in the diesel engine as a technology that "squats" from a diesel engine? The answer is that diesel cars don't exist only, and they “have to give up treatment.” Usually we see three scales on the diesel engine's oil gauge, which are low, high, and fuel dilution scales. Theoretically, as long as the oil does not exceed the fuel dilution scale, no need to worry.

The solution to increased oil

First of all, the problem of increased engine oil can be solved in the engine design. In the early stage of engine development, the crankcase ventilation was used to volatilize the gasoline entering the crankcase into the atmosphere. However, due to the current environmental protection standards, almost all engines are now PCV system installed. PCV is a shorthand for Positive Crankcase Ventilation. When the engine heats up, the gasoline volatilizes and then reenters the combustion chamber through the fuel separator and the intake manifold. Second, delay the timing of fuel injection to reduce the possibility of gasoline entering the crankcase through the piston ring gap. It can also reduce the ignition advance angle, make the engine temperature rise faster, accelerate the volatilization and evaporation of gasoline in the crankcase, and increase the idle speed of the cold vehicle to allow the engine temperature to rise as quickly as possible.

Can more oil damage the engine?

After reading this, I believe that many people can make an objective judgment on various issues on the Internet, such as “increase in engine oil” and “engine major flaws”. For everyone's concern, the increase in motor oil will not cause damage to the engine, as a small series of engineering students, for the moment that it is difficult to answer this question. First of all, the problem itself is problematic. In the crowd of car buyers, there are people who use cars, car users, perfectionists, there are cars as arts and crafts for there, and cars as vehicles, through analogy For diesel vehicles, it is now possible to determine that the engine oil will not cause major damage to the engine until the engine oil has exceeded the limit of PCV work (fuel dilution scale).

In foreign countries, one car can be passed from grandpa to grandson, and the engine can still be used. Modern engine technology, especially materials, is far superior to the previous engine. The Honda CR-V 1.5T uses the same engine at home and abroad. For domestic problems, some foreigners are out of curiosity to get the engine oil with more oil to get a professional testing agency to determine the results, the results show that the metal element content is normal, due to domestic Most of the models are based on gasoline engines, which also leads to a higher awareness of the increase in motor oil in the overseas population than in the domestic market. And taking into account China's 15 years of retirement system, especially in some cities, about 10 years of vehicle travel are very limited. From an objective point of view, this time the domestic consumer has reacted slightly to the increase in oil incidents.

The headline says: Because China's car culture has not experienced the initial development of the automobile industry, in many people's hearts, the car is still the "imported product" of the year, and it lacks some basic knowledge about the car. Xiao Bian this time only from the engine's own technical level analysis of this already very traditional "new problems." For the engine oil of the protagonist Honda CR-V, the former “Oil Throttle” will not affect the engine. Xiao Bian will invite third-party professionals in future articles to bring more authoritative analysis. Please stay tuned!