簡單講:
活塞環(較小)與缸壁接觸少, 油膜接觸多, 摩擦力小, 機油消耗大
活塞環(較大), 反之
這裡所謂大小, 指的是不漏氣為範圍
下面有一篇簡單易懂的, 重點有加底線
關於降低活塞環磨擦的文章相當多, 有興趣google, 關鍵字 piston ring designs reduced friction
Engine Oil Consumption - MINI Cooper S (turbocharged engine) 2007-2010 (R55, R56, R57)
Abstract: Overview of engine oil consumption (turbocharged engine). This articles presents: "Key Concepts" (theory of operation); how to proceedure for checking oil, and a video overview of performing an oil check on a MINI Cooper S 2007-2011.
Applies to: MINI Cooper S: 2007-2011 (R56, R55, R57)
Video Overview of How to Check Oil
How to check your engine oil level
Key Concepts
Dealing with Engine Oil Consumption
Technical Information on Oil Consumption
What does engine oil do?
Lubrication
Cooling
Prevention of corrosion and sediment
Engine oil consumption
Summary
Measuring oil consumption
Related
Video Overview of How to Check Oil
How to check your engine oil level
Most engines have a dipstick for measuring the oil level. The following procedure must be
followed to ensure indication of the correct oil level:
1. Park vehicle on flat and even ground with the engine at operating temperature,
i.e. after uninterrupted driving for at least 10 km (6.2 miles).
2. Turn off the engine.
3. After waiting approximately. 5 minutes, pull out the dipstick and wipe with
a lint-free cloth, paper tissue or similar.
4. Carefully insert the dipstick as far as it will go into the dipstick tube and
pull out again.
5. The oil level must be between the two marks on the dipstick.
Depending on the type of engine, the amount of oil between the two marks on the
dipstick is approximately. 1 - 1.5 liters.
Note: Do not exceed the upper mark on the dipstick otherwise engine
may be damaged by over filling with oil.
Key Concepts
Dealing with Engine Oil Consumption
Modern engines can consume up to 0.63 US quart (0.6 liter) within 1000 miles (1600 km) of driving. Make a habit of checking you engine oil regularly, for example; each time you refill your fuel tank. An engine run low on oil can create additional stress on mechanical components, resulting in engine failure.
MINI recommends using: MINI Long Life engine oil. Check with your local MINI dealer for latest specification.
Technical Information on Oil Consumption
What does engine oil do?
Engine oil is one of the most important operating fluids in a combustion engine. Without engine oil, the engine cannot operate correctly. The principal functions of the engine oil are:
Lubrication
Cooling
Prevention of corrosion and sediment
Lubrication
The engine oil / lubricating film is subject to varying requirements. The engine oil must not have excessively high viscosity at low temperatures to guarantee optimum lubrication even when the engine is cold (cold start). On the other hand, the engine oil must not be too thin at high temperatures as this could cause have a negative effect on the lubricating film, even canceling the lubricating effect altogether.
The engine oil's most important job is to minimize friction between metallic surfaces. This is realized by a lubricating film that forms between the surfaces of moving engine parts while the engine is running. The thin film of oil greatly reduces friction, leading to reduced wear and less heat generation. Besides preventing pistons from seizing and bearings from being damaged, the service life of all engine parts involved is increased and fuel consumption is reduced.
Another function of the oil film is to seal the combustion chamber from the crankcase via the piston rings.
Cooling
The pistons reach their normal operating temperature just a few moments after the engine is started. Depending on the ambient temperature, engine configuration and driving style, it may take a few minutes until the engine block, and so the cylinder walls, to reach optimum operating temperature. To prevent the engine from exceeding the operating temperature, it needs a properly functioning cooling system. The engine oil is frequently underestimated or overlooked as an important cooling element, alongside air and coolant water. Yet the engine oil is responsible for a large degree of cooling inside the engine. To cool the piston crowns directly, nearly all MINI engines are equipped with oil spray jets that moisten the piston crowns with engine oil.
Prevention of corrosion and sediment
Not least, the engine oil has the job of protecting the engine against corrosion and sediment. Aggressive combustion residue is neutralized by the lubrication oil and appropriate additives. Other combustion residue is conveyed in the oil circuit to the oil filter where it is filtered out, or it deposits in the oil sump.
Engine oil consumption
Engine oil consumption is determined above all by the configuration of the individual construction groups and systems. It is system characteristic that every combustion engine consumes lubricating oil. The principal causes of this engine oil consumption are:
Pistons with piston rings
Valve stem seals
Crankcase ventilation
The surface topography of the cylinder liners and piston rings is the primary variable that directly influences engine oil consumption, as the piston rings do not provide perfect sealing, but rather form a metering mechanism. In the configuration, there is a conflict of interests between engine oil consumption and friction reduction. The latter has a direct effect on power output and fuel consumption. With every stroke of the piston, minimal quantities of engine oil remain on the cylinder walls. These are indispensable for lubricating the piston rings (see lubricating film above). As the piston moves downwards, the engine oil on the cylinder wall is plays a role in combustion close to the walls and is then expelled along with the combustion exhaust gases. The higher the engine speed, the greater the effect, because there are more combustion cycles for each time unit. For this reason, engines with a high-speed concept tend to have higher engine oil consumption than other engines. The same applies to the lubricating film on the valve stems.
The measurable result in engine oil consumption is primarily influenced by the quality of the fuel used and the driving profile. For example, if in the winter you drive a lot for short distances (= high fuel entrainment as the evaporation temperature is mostly only reached briefly) and then a long distance (fuel can then evaporate readily), this journey will cause a considerable drop in engine oil level. This is not engine oil consumption, but rather a change in engine oil level caused by the fuel content in the engine oil. Customer complaints are often the result of this effect. It can happen that the engine oil level drops by more than 1.05 US quart (1 liter) after driving just a few hundred miles (kilometers). Moreover, the measuring system on some engines (dipstick / QLT) have a tolerance of up to 0.31 US quart (0.3 liters).
But evaporated particles of oil also escape through the crankcase ventilation (expulsion level technically never 100 %) and plays a role in combustion with the intake air. Configuration is especially difficult here. On the one hand, the engine oil should be expelled as completely as possible. On the other hand, crankcase pressure requirements must be satisfied. Other expulsion systems only work optimally with a certain gas throughput, the expulsion effect deteriorating with greater or lesser gas volumes.
Summary
It is a technical necessity that very combustion engine consumes engine oil. The level of the engine oil consumption is greatly influenced by driving style and by the fuel used.
Measuring oil consumption
Oil consumption rate of an engine can only be determined by the by the amount of engine oil needed to top up.
Engine oil is added as soon as the level drops below the max. mark on the dipstick, regardless of certain fundamental rules such as horizontal vehicle position, drain time etc. This can easily cause the level to become too high due to the size of the container which happens to be available.
Excess engine oil can damage the engine and is consumed more quickly due to the splash effect.
For this reason, allow the engine oil level to drop as far as the min. mark before adding the required topping up quantity, (only when checking engine oil consumption amount).
The difference between the two marks corresponds to about 1.05 - 1.6 US quarts (1.0 - 1.5 liters).
abcpanadol wrote:
前半部同意, 活塞環...(恕刪)
樓主沒說明騎乘時會不會噴藍煙，如果噴得很明顯那就影響到一般用路人的權益了，你應該不喜歡一台狂噴煙的破車在你前面停著吧?
拉轉如果沒有噴藍煙但是卻有機油短少現象，搞不好是其他地方漏油，或許不需要花很多錢就可以解決了
機油短少的狀況很多，汽門油封 區軸油封 汽缸壁與活塞環不正常磨損的機油燃燒 等等，如果是不正常磨損造成的機油燃燒，拆解後若是區軸的間隙正常，再檢視活塞環與汽缸壁的狀況，最壞打算來講就是重新塘一下再配一個耐用的活塞以及活塞環就解決了，在順便巡視一下缸頭的狀況，看進排氣有沒有機油滲出，這種問題還不會太煩悶....
自己的老車壞很多次了，只要引擎不出怪手我不太會煩心車子上的事情
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