汽车发动机英语教程 Lesson 10 pistons 活塞 英汉对照

Lesson 10  pistons

活塞

 

The piston with its rings,  seals the cylinder and transmits the gas pressure to the connecting rod.

It absorbs heat from the gas, and this heat must be carried away if the metal temperature is to be held within safe limits.

The constant reversal of the piston travel sets up inertia forces, which increase both with the weight of the piston and with its speed.

For this reason designers try to keep piston weight low, particularly in high-speed engines.

活塞，连同活塞环密封汽缸，并把气体的压力传递给连杆。

活塞从气体吸收热量。假如要使金属的温度保持在安全限度以内，就必须散热。

活塞行程的不断往复产生惯性力，此力随活塞的重量和及其速度而增大。

为此，设计者设法使活塞造得轻些，特别是高速发动机。

 

In “uncooled” pistons, the heat absorbed by the piston top travels through the piston side-walls, then through the rings into the cylinder walls and finally to the jacket water surrounding the cylinder.

In highly loaded engines, additional means of heat removal are necessary; this is accomplished by a liquid, generally oil.

These are termed “cooled” pistons.

在无冷却的活塞中，活塞顶部吸收的热量通过活塞侧壁，再通过活塞环，传入汽缸壁，最后，传向包在汽缸周围的水套中的水里。

在那些高负荷的发动机中，散热的附加措施是必要的。采用液体通常是油液进行冷却。

这种活塞被称为“冷却”活塞。

The top section of a piston is called the crown and the lower section the skirt.

The shape of the top of the crown depends largely on the design of the combustion chamber.

The crown section is usually thick, in order to withstand the gas pressure without distorting and to provide a good path for the heat flow from the upper surface of the crown to the rings.

When running the piston diameter increases because of the increase in temperature.

To take care of the greater expansion in the high-temperature zone, the crown is machined on a slight taper, the diameter being greatest where the crown meets the skirt and becoming less toward the top.

活塞的顶端部分称为活塞顶，下面部分称为活塞裙。

顶部的形状主要取决于燃烧室的设计。

为了承受气体压力而不变形，并让热流从活塞顶表面传向活塞环提供良好通道，活塞顶部通常很厚。

在运行中，因为温度升高，活塞直径增大。

考虑到高温区热膨胀较大，活塞顶部加工成低小锥形，即活塞顶部和活塞裙部交接处直径最大，愈向顶部直径愈小。

 

The crown carries the upper set of rings, which are the “compression”, or “power rings”.

In most uncooled pistons, a division plate above the wristpin prevents lubricating oil from splashing against the hot under-surface of the crown.

The amount of splashed oil would be insufficient to cool the piston; consequently, the oil would overheat and carbon deposits would form.

活塞顶部装有一组上活塞环，是压缩环或动力环。

在多数不冷却活塞中，活塞销上的隔板防止机油飞溅到活塞顶下部的热表面。

飞溅的机油量不足以冷却活塞，因此，机油就因过热而形成积碳。

 

The skirt of a trunk piston takes the side-thrust of the connecting rod and prevents the piston from rocking from side to side; it also carries the lower set of rings, which are the “oil-control” rings.

Below the upper ring band, where heavy wall thickness is needed to carry the heat flow, the piston skirt becomes much thinner.

The running clearance between the skirt and the cylinder wall must be small; therefore, it is important that the thin skirt should stay truly round.

For this reason, interior ribs are used to stiffen the skirts of cast pistons.

筒状活塞的裙部承受连杆的侧向推力，并防止活塞从一侧向另一侧摆动，裙部也装有一组下活塞环， 为机油控制环（油环）。

活塞的上环带的下面，必须有足够的壁厚，以防止传热（携带热流），而活塞的裙部可薄一些（变得更薄。）

活塞的裙部和汽缸壁之间的运行间隙很小，因此，活塞薄薄的裙部保持真正的圆形很重要。

基于这种原因，使用内埋加强筋以增加铸件活塞裙部的硬度。

 

The ideal piston material would be light and strong, conduct beat well, expand only slightly when heated, resist wear, and be low in cost.

Formerly, all pistons were made of cast iron but today the alloy cast irons, which offer greater heat resistance and better wearing qualities, are widely used.

These materials are not perfect as regards weight and heat transfer ability, but nevertheless are quite satisfactory in slow-speed engines, particularly where the piston is effectively cooled by a liquid.

理想的活塞材料应该重量轻，轻度高，导热性能好，热膨胀很小，耐磨，成本低。

从前，所有的活塞都用铸铁制造，但今天，广泛采用合金铸铁，它能提供更好的耐热耐磨性能。

这些材料在重量和传热能力方面不是很理想（完美），但是，尽管如此，它对低速发动机，特别是对那些用液体充分（有效地）冷却活塞的发动机是十分合适的。

Composite pistons.

Forged steel crowns and cast-iron skirts have been combined in pistons for large engines, to obtain the strength and heat resistance of steel in the upper section, where these properties are important, and the good wearing properties of cast iron in the lower section, where the piston bears against the cylinder.

组合活塞（合成材料活塞）

锻件活塞顶和铸铁活塞裙部组合而成的活塞用于大型发动机中，以便在活塞的上部分获得刚的强度和耐热这些重要的特性，而在紧靠汽缸的活塞下部获得铸铁的良好耐磨特性。

Many cast-iron pistons are electroplated with metals like cadmium and tin.

The purpose is to permit closer clearances(giving a quieter engine), assure proper run-in (that is, the seating of a new piston), eliminate seizing and provide longer life。

In some designs, wear is reduced by using inserts of antifriction metal in the piston walls.

许多铸铁活塞采用镉与锡之类的金属镀层。

目的是获得更小的间隙（使发动机噪音小），保证良好的磨合（也就是，新活塞的磨合）避免卡死并延长使用寿命。

在某些设计中，在活塞壁上采用镶嵌耐磨金属材料以减少磨损。