【正文】 Any final soluti。 Webs bend due to this loading but they also have a tendency to twist. 由于這 個(gè)負(fù)荷曲柄臂會(huì)產(chǎn)生彎曲，但是它們也有一個(gè)扭轉(zhuǎn)的趨勢。 This torque imposes stresses on the crankshaft journals. 扭矩在曲軸軸頸上產(chǎn)生扭轉(zhuǎn)力。 Current designs make considerable use of puter finite element analysis which allows a wide range of loadings, dimensions and cylinder firing orders to be analysed before any manufacture takes 方法，在任何生產(chǎn)之前，都對(duì)大負(fù)荷范圍、不同尺寸和汽缸點(diǎn)火順序等進(jìn)行分析。 Solid fing avoids stress problems, which would result from the presence of shrink fits, and ensures even stress transmission between journals, webs and pins. 實(shí)鍛避免了因收縮配合帶來的應(yīng)力問題，避免了軸頸、曲柄臂和曲柄銷上的應(yīng)力集中。 Bearing technology continues to change to meet the demands of higher loads but problems of lubricants contaminated by water and residual fuels must also be overe. 軸承技術(shù)不斷發(fā)展為滿足了更大負(fù)荷的需要，但是還需要克服由于水和殘油對(duì)潤滑油所造成的污染問題。 During the 1990s a number of engine builders returned to bimetal bearings which employ a layer of aluminiumtin on the steel backing shell. 在 20 實(shí)際 90 年代，一些柴油機(jī)廠又從 新生產(chǎn)在鋼襯殼內(nèi)部加一層錫鋁合金的雙金屬軸承。 The use of overlay material provides a degree of protection against corrosion, while a thin layer of nickel prevents the lead in the overlay from migrating into the leadbronze layer 覆鍍材料能夠?qū)Ωg提供一定程度的保護(hù)，覆鍍一薄層的鎳就能夠防止鉛向青銅層的遷移。 Early arrangements simply had a layer of white metal on the steel backing shell but this gave way to the multilayer bearing with a layer of leadbronze or copper between the steel and white metal in order to improve adhesion. 早期的軸瓦只是簡單的在薄鋼襯殼內(nèi)部澆注一層白合金，但是這種制作方法為多層軸瓦提供了借鑒，多層軸瓦是在薄鋼襯殼和白合金之間又加了一層鉛青銅或者黃銅來提高金屬間的粘著力。 indeed no scraping is possible due to the thin layer of bearing material present. 這種 類型的軸承只需要表面拋光，不需要過多處理，實(shí)際上由于軸承材料層很薄沒有必要進(jìn)行刮擦等處理。 This type of bearing essentially consists of a thin steel backing shell with a layer, or layers, of bearing material cast, flashed or deposited on the rubbing surface. 這種類型的軸瓦基本上是在薄鋼襯殼內(nèi)部的粗糙的表面上澆注或沉淀一層或多層的軸承材料。 Main bearings for medium speed engines currently in use are of the thin shell type. 中速機(jī)普遍使用薄瓦性的主軸承。 These bearing caps are guided laterally into the engine block at the top and bottom and the hydraulic jacks are often permanently fitted to allow for ease of maintenance. Hydraulically tensioned horizontal side studs support the main bearing caps and with the vertical studs and lateral guide arrangements provide a very rigid main bearing support for the crankshaft. 主軸承蓋可從上部和下部橫向?qū)霗C(jī)體結(jié)構(gòu)，為了方便維護(hù)保養(yǎng)經(jīng)常安裝固定式的液壓千斤頂。 Although this type of arrangement can, in theory, be incorporated within a monoblock engine structure, it is not used. An underslung main bearing support system is preferred. Nodular castiron bearing caps are held from below by means of two hydraulically tensioned studs. 盡管理論上可把這種設(shè)計(jì)的軸承蓋與整體式機(jī)體結(jié)構(gòu)做成一體，但實(shí)際中并不這樣做。潤滑油的吸入口和過濾器都安裝在油底殼中。 With monoblock structures, a subframe is required to act as the engine sump. This subframe, which bolts directly to the lower face of the engine structure, takes no load and can be manufactured from welded plate. Lubricating oil suction pipes and strainers are arranged within the sump. 對(duì)于整體結(jié)構(gòu)來說，下部結(jié)構(gòu)被用作柴油機(jī)的油底殼。一些機(jī)型（如： Wartsila Vasa 38）將進(jìn)氣總管與機(jī)體集成在一起，而水和油的通道則采用鑄造或車削后，做為機(jī)體結(jié)構(gòu)的部件。使用貫穿螺栓并不是意味著設(shè)計(jì)上存在缺陷，而是在需要的地方有效地利用加強(qiáng)機(jī)構(gòu)。一些柴油機(jī)還利用長貫穿螺栓從主軸承的下表面通到構(gòu)件的上部為整個(gè)機(jī)體進(jìn)行額外加強(qiáng)。 Modern Cast Monoblock Structure 現(xiàn)代整體鑄造結(jié)構(gòu) Engines designed during the 1990s generally employ a cast monoblock form of construction with the cylinder block and bedplate forming a single cast iron structure. This nodular iron casting provides considerable rigidity due to its singlepiece design and construction. In some engines additional strengthening can be provided by long tie rods extending from the lower face of the main bearing to the upper part of the structure. Tie rods are also employed between the upper face of the cylinder head and the lower face of the intermediate frame structure to ensure that bustion loads are transmitted from the cylinder head to the engine frame structure. The use of tie rods does not imply a weakness in design and is an effective use of a strengthening mechanism where it is needed. A rigid structure is necessary in order to preserve alignment of all engine parts, particularly the crankshaft and camshaft, and to minimize problems related to vibration of the structure. Some engines (. Wartsila Vasa 38) have the air inlet manifold as an integrated part of the engine block while many water and oil channels are castin or machined as part of the engine structure. Such features make for easier maintenance, improved accessibility and a reduction in the number of engine parts. 在 20 實(shí)際 90 年代，柴油機(jī)設(shè)計(jì)開始運(yùn)用整體鑄造結(jié)構(gòu)，把汽缸體和機(jī)座一起鑄造成一個(gè)鑄鐵構(gòu)件。如果是鑄鐵機(jī)體的話，就很少有構(gòu)件厚度方面的要求，為了保證熔化的鐵水能夠容易地流到所有的部 位，構(gòu)件的厚度一般要比能承受實(shí)際應(yīng)力的厚度大得多。有些情況下，用貫穿螺栓以一定壓力把主軸承座和汽缸體連接在一起，鋼制的貫穿螺栓從汽缸體的上部一直通到機(jī)座的下表面（主軸承下部）。為了保證剛度，機(jī)體結(jié)構(gòu)通常是由鑄鐵材料鑄成一個(gè)整體。s structure. In some cases tie rods are employed to maintain the main bearing housings and engine block in pression. The steel tie rods pass from the upper part of the cylinder block to the lower face of the bedplate below the main bearing housing. Smaller engines often have no tie rods as the structural section thickness is great enough to keep tensile stresses reasonable during peak pressure periods. With a casting there is a minimum section thickness requirement to ensure that the molten metal flows readily to all parts and this thickness is often greater than that dictated by actual stress considerations. Accurate alignment between bedplate and cylinder block is essential to effective stress transmission and engine operation. 傳統(tǒng)柴油的結(jié)構(gòu)中包含有一個(gè)用來安裝汽缸套的汽缸體，發(fā)動(dòng)機(jī)是直列式布置還是 V型布置就造成了汽缸 體設(shè)計(jì)形式上的差異。十字頭式柴油機(jī)有時(shí)使用活塞的底面作為掃氣風(fēng)機(jī)，來協(xié)助完成渦輪增壓循環(huán)。 The flow of air may all pass through the pressor of the turbocharger and then through the scavenge blower in series, or part of it may pass through the pressor and part through the scavenge blower in parallel. 所有的流動(dòng)空氣都經(jīng)過渦輪增壓器的壓氣機(jī)，然后經(jīng)過串聯(lián)的掃氣風(fēng) 機(jī)，或者是一部分空氣經(jīng)過壓氣機(jī)，另一部分經(jīng)過和