学习知识之主机活塞清洁环（Piston Cleaning ring ）
建议船东和二冲程船用主机操作者学习此篇.爱学习者也可以阅读。
It is recommoned that the shipowners and operators of MAN B&W two-stroke marine diesel engines to read. If you are intersted in it, please start to read.
近期收到专利公司关于活塞清洁环使用方面的服务信（Service Letter直译）,也有的叫专利通讯的。为了让大家更清楚的了解，对该服务信做一个详细的解读。
Recently, We received a service letter from the MAN-ES about th piston cleaning ring. I don't know if you have received it and carried out. In order to let you know more clearly, I want to make a detailed introduction of the service letter.
随着时间的推移，活塞设计高度增加，以确保气缸状况。但是由于高度增加，活塞上部沉积物变得比较短的活塞发动机更为严重。因此在2000年左右，专利公司引进了活塞清洁环的设计。（关于活塞头的设计发展历程将有新的专题）
The piston crown top land height has increased over time to secure the cylinder condition. Because of the increased top land dimensions, deposits on the top land have become more critical than for shorter top land engines.The PC-ring has been introduced since 2000.（PS：For the development of piston will be pubished in new topic.）
活塞清洁环布置在缸套的顶部。当活塞运行到接近上死点（TDC）时，通过安装的活塞清洁环刮掉活塞头上部沉积物，以防止活塞头上积聚过多沉积物。
The piston cleaning ring is arranged in the top of cylinder liner.The piston cleaning ring is installed to protect against excessive deposit build-up on the piston crown top land by scraping off the deposits when the piston approaches top dead center (TDC).
活塞清洁环也会随着使用经验的积累而进行设计更新。
The piston cleaning rings are updated with the accumulation of experience.
1.缸套检修
Cylinder overhaul
活塞清洁环和气缸套的设计总是相互遵循。因此，在对气缸单元进行检修时，必须检查和清洁活塞清洁环，如果完好，则重新使用。
The PC ring and cylinder liner are designed to always follow each other. Therefore, when a cylinder unit is overhauled, the PC ring must be inspected, cleaned and if intact, reused.
如果由于某种原因将活塞清洁环从缸套上拆下，则必须在部件上标记正确的位置。活塞清洁环必须安装在与拆卸时相同的位置，因为它与缸套一起磨损。
If the PC ring is removed from the liner for some reason, it is important to mark the correct position on the parts. The PC ring must be installed in the same position as when removed, because it is worn together with the cyl-inder liner.
若是活塞清洁环的磨损程度与缸套相同，因此在检修期间无需更换活塞清洁环。
Since the PC ring is worn to the same extent as the liner, it is not necessary to replace the PC ring during over-haul.
拆前标记
安装时对齐
2.新缸套
New liner
安装新缸套时，也必须安装新的活塞清洁环。
When installing a new liner, it is mandatory to install a new PC ring too.
3.修复缸套
Reconditioned liner
当安装一个修复的缸套（当缸套在活塞裙上死点位置磨损超过规定的临界尺寸）时，必须安装一个与缸套内径相匹配的活塞清洁环，因为它们是需要匹配的。（参见说明书页2265-2207-0001）
When installing a reconditioned liner (when the liner is worn beyond the defined critical dimension in the skirt TDC position) a PC ring must be installed which matches the new bore diameter, and it must follow the liner as they are a matched item.
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获取中英文对照说明书页2265-2207-0001
4.不带活塞清洁环的运行（不推荐）
Operation WITHOUT a PC ring (not recommended)
既然活塞清洁环的作用是防止沉积在活塞顶环上，如果不使用活塞清洁环，则导致活塞上部沉积过多。
Since the function of the PC ring is to protect against deposits building up on the piston crown top land, op-eration without a PC ring can lead to excessive deposit formation on the top land.
活塞上部的沉积物会对单元状况产生负面影响。可能导致缸套表面抛光，也可能导致活塞环和缸套之间缺乏润滑，最终导致活塞环或活塞裙部磨损。
Deposits on the top land can have a negative impact on the
condition of the unit. It may cause polishing of the liner surface and also lead to a lack of lubrication between the piston rings and liner, which eventually can result in piston ring or piston skirt scuffing.
沉积物堆积也会影响活塞在气缸内的位置，并导致缸套和活塞裙之间的高摩擦。这种情况可能导致缸套和活塞裙严重损坏，必须避免。
A deposit build-up can also affect the position of the pis-ton inside the cylinder and cause high friction between the liner and piston skirt. This situation may lead to se-vere damage of the liner and skirt, and must be avoided.
不建议在没有活塞清洁环的情况下运行，只有在没有活塞清洁环可用的紧急情况下才允许操作，这种情况应该尽快改正。
Operation without a PC ring cannot be recommended and is only allowed in emergency situations when no PC ring is available. The condition should be rectified as soon as possible.
回顾我们之前关于缸套检修和活塞清洁环评估的说明，认为有必要发送此更新，并给出明确的指示，除非活塞清洁环损坏到不能再使用的程度，否则不要拆下活塞清洁环。修订后的说明载于文件2265-2207-0001。
A review of our previous instruction for cylinder overhaul and PC ring evaluation has deemed it necessary to send out this update, and to give the clear instruction not to remove the PC ring unless it is damaged to an extent where it can no longer be used. The revised instruction has been included on the document 2265-2207-0001.
如果由于损坏而必须更换活塞清洁环，只要活塞裙部TDC位置的缸套磨损小于孔径的0.1%，则可以将新的活塞清洁环安装到磨损的缸套上。的说明书页2265-2207-0001说明了活塞裙TDC位置的定义和测量方法。
If the PC ring has to be renewed because of damage, a new one can be fitted to a worn liner provided that the liner wear in the piston skirt TDC position is less than 0.1% of the bore diameter. The instruction 2265-2207-0001 shows the definition of the skirt TDC position and how to measure it.
注意，缸套磨损的评定不应以缸套最大磨损为依据，而应考虑活塞裙部缸套的磨损量。
Note, that the evaluation of the liner wear must NOT be based on the liner maximum wear but on the wear mea-sured in the the piston skirt TDC.
如果活塞清洁环断裂或损坏，并且活塞裙部TDC位置的缸套磨损超过0.1%，请联系MAN Energy Solutions获取进一步指导。
If the PC ring is broken or damaged and the liner wear exceeds
0.1% in the piston skirt TDC position, please contact MAN Energy Solutions for further guidance.
如果由于某种原因无法更换缸套，则应咨询MAN Energy Solutions，以获得指导如何进行的操作。
If for some reason it is not possible to exchange the liner, MAN
Energy Solutions should be consulted for guidance on how to
proceed.