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1、精选优质文档-倾情为你奉上The ma chine pi ston connecting rod set- deta i l edex position of pistonThe piston connecting rod set is composed of the piston, piston wreath, piston pin, connecting rod, connecting rod axle bush, etc. . effect: The effect of the piston is to bear the air pressure, and pass to connect
2、ing rod to drive the bent axle to revolve through connecting rod axle bush, the piston coping is still a part of the burningroom.Theworkcondition:Pistonworksunderthe conditionofheat,highpressure,highspeed,andbad lubrication.Pistondirectlycontactswiththeheatair.The temperature can amount to above 250
3、0 Ks in a moment .The piston is heated severely, but the condition of spreading the hot is bad .So while the piston works, the temperature is very high and thecopingisuptothe600-700Ks:Andthetemperature distributesasymmetrically;Thepistoncopingbearsgreat air pressure, especially the pressure is great
4、est in the route of doing efficacy. The gasoline machine is up to the 3-5MPas, the diesel engine is up to the 6-9MPas.This makes the piston produce pound,1专心-专注-专业and bear the function of the side pressure. Therefore, the pistonshould have enough heat-proof, try to decrease the heating area, strengt
5、hen the cooling of the piston, to make the highest temperature of the coping descend .The piston moves at very high speed(8-12 ms/ s) back and forth in the air cylinder, and speed changes constantly, This produces very great inertial dint, making the piston bear great additional load working under s
6、uch bad condition, the piston will become deformed heating power. At the same time ,it slitters the chemical corrosive power of the burning gas .In order to descend the inertial dint of back and forth, we must ease the weight of the piston as possible .Piston works under the condition of the heat, h
7、igh pressure, high speed(the average speed can amount to the m/ s), and its lubricant condition is bad and the frication between the piston and the air cylinder wall is very great. In order to descend the friction, the surface of the piston surface must be wear-resistant.Request:(1) To have enough r
8、igidity and strength, and the reliable dint;(2) Transmit heat well, bear the high pressure, bear the heat and1bear to wear away;(3) the quantity is small, the weight is light, descend the inertial dint of back and forth as possibleThe aluminum metal alloy material satisfies the top requests basicall
9、y, therefore, the piston generally adopts the high strength aluminum metal alloy, but some low speed diesel engines adopt high class iron casting or heat-proof steel, str ucture: The piston can be divided into three parts, piston coping, the piston head and piston skirt departments.1. The piston cop
10、ingThe piston coping bears the air pressure, it is a part of the burnable room .Its shape, position, size are relevant to the concrete from of the burnable room. They are made to satisfy the combustible hybrid spirit formation and burnable requests. Its coping shape can be divided into four major ty
11、pes, a flat coping piston, a convex coping piston, a concave coping piston and model piston.A convex coping piston is usually used on the two blunt distanceI.C. engines, It is good to improve the process exchanging the gas .Modern four blunt the distance gasoline machine also adopts1the convex copin
12、g piston in order to strengthen the effect ofpushing the gas or extend the ratio of compressing .Convex of a piston coping presents a form of ball, its coping strength is high, having an effect of leading, being advantageous to improve the process of exchanging the gas, two route of travel gasoline
13、machines often adopt the convex coping pistonA piston coping presents the hollow form, the shape and positions of the cave pit must be advantageous to the combustion of the combustible and hybrid gas, having a pair of eddies concave pit ball, concave pit, U concave pit, and so on.2. Piston headThe p
14、iston refers to the first piston wreath to the part above the piston pin.It has several wreath slots, which are used to install the piston wreath and have an effect of sealing completely. It is also called the leak proof department .The diesel engines compress ratio is high, and generally have four
15、wreath slots, The three upper wreaths are used to install, the lower part installs the oil wreath. The gasoline machine has three wreath slots generally, which are two jet of gas wreath slots and an oil wreath slots. At the bottom1of oil wreath slot many paths toward eyelet are drilled to make thequ
16、ilt oil wreath flow from the air cylinder wall to the oil bottom hull through these eyelets. The working condition of the wreath slot is the worst and should leave the coping generally a little farther.Above the gas wreath, a narrow insulating slot is usually set to cut off the heat flow which is sp
17、read from the piston coping to the first gas wreath and make parts of calories from a piston wreath spread, thus easing the hot burden of the first gas wreath. On some engines small wreathe slots are often made between the coping head and the first gas wreathe, sometimes till a few more wreath. This
18、 kind of small wreath can adsorb the lubricant because it accumulates the carbon. It can keep piston and the air cylinder walls from biting to match when it work in the condition of losing oil, so it is called accumulating the carbon slot.The calories that the piston coping absorbs also mainly passe
19、s the air cylinder wall through the piston wreath to leak proof department, again spread by the cool water.In a word, the function of the piston head is in addition to install the piston wreath, still1seal completely function and transmit heat function, sealingcompletely the air cylinder together wi
20、th the piston wreath, keeping combustible admixture spirit from leak crankcase, at the same time pass the(70-80)%calories to the air cylinder wall through the piston wreath.3. Piston skirt departmentThe piston skirt department refers to the parts from the bottom of the oil wreathe slot. It includes
21、the pin which is used to pack the piston. The piston skirt department exercises to rise to lead to the function to the piston in the back and forth in the air cylinder, and bear the side pressure. The length of the skirt department is decided by the size and the piston diameter of the side pressure.
22、 The so-called side pressure mean in the compression route of travel and make route of travel of efficacy .The level component of the gas pressure which take effect on the piston coping presses the piston to the air cylinder wall. Compress the route of travel and make the side pressure direction of
23、the efficacy route of travel air exactly the opposite, because of the combustion pressure consumedly high in compress the pressure, so, make the side in1the route of travel of efficacy pressure also consumedly high incompress the side in the route of travel pressure. Tw o on the sides that bear the
24、side pressure of the piston skirt department be called to push the dint to face, they be placed in to sell the mutually perpendicular direction of the stalk line with piston up.Structure characteristics:(1) make into oval in advance:The wall thick of the piston skirt department is bigger along the d
25、irection of the pin and the hot inflation have great capacity. While working under the common function of hot burden and the side pressure the skirt ministry becomes the oval pillar form. Following the piston to pin direction it has the elongation slightly, but the perpendicularity pin direction it
26、has slightly short. In order to make piston in working condition still keep the cylinder form and prevent from resulting in piston choked to death or the part wore away big because of oval transform, the piston skirt department processes generally and in advance oval, its major axis and pistons sell
27、 the stalk direction perpendicular. In order to reduce the heat transform around the piston, we can also make the1surface of skirt cast into bottom to sink the 0.5-1 mmsIn order to make both sides of skirt bear the air pressure and keeping with air cylinder small but safety of cleft, while working t
28、he piston must have right of cylinder form. But, because the thickness of the piston skirt department is very asymmetry, the piston pin the metals of a bore part thick, be subjected to the hot inflation to have great capacity, follow the piston to sell a stalk line direction of transform to have gre
29、at capacity in other directions. Moreover, the function that bears the air side pressure, causes the piston to transform the more perpendicular piston of quantity pin the direction big.Thus, if the piston in cold state hour skirt department is a circular, while working the piston will become on oval
30、, making a circumference cleft of the piston and air cylinder not equal, resulting in piston block in the air cylinder and the machine cant work normally. Therefore, while processing we make the piston skirt department into the oval shape in advance. The direction of oval major axis is perpendicular
31、 with the pin. The direction of the minoraxis follows the direction of the pin. Thus while working the1piston work tend the near positive circle.(2) The temperate of the piston along the direction of the length is very asymmetry. The temperature of the upper part of the piston is high, the lower par
32、t is low, it is upper part that the inflation quantity also correspond big, the lower part is small. In order to make the piston top and bottom diameter tend equal, that is to say the cylinder form, must make the piston into the top smaller the bottom the big stairs form in advance, taper.(3) In ord
33、er to reduce the calories of the piston skirt department ,we usually open the hot slot horizontally in the skirt department. In order to compensa the skirt department after be subjected to the heat of transform the quantity, the skirt department opens lengthways of inflation slot. The shape of the s
34、lot contain T form or form slots. The horizontal slot opens generally under most the underneath of a wreath slot, both the edge pin sides ( also opened in the oil wreath slot) of on the skirt department so as to reduce the head calories delivered toward the skirt department, so it is called separati
35、ng the hot slot. The vertical slot will make the skirt department have the certain flexibility so1as to the possibly small cleft with the air cylinder while thusmaking piston assemble, but at hot state have the in expiation of function again, result in piston choked to death in the air cylinder unli
36、kely, past be called vertical slot inflation slot. The skirt department will make it open a side of the slot after open the vertical slot just the degree diminish, bearing the side a side that pressure is smaller in assemble should make it locate make route of travel of efficacy .The diesel engine p
37、iston is subjected to the dint big, the skirt department does not open the slot generally.(4) In order to ease the weight some pistons slice one part in both sides that opens the bore or is free from the side pressure to the skirt department, to eliminate the inertial dint, to reduce neighborhood of
38、 heat transform the quantity, and form drag along the plank type piston or short piston.The flexibility between of the plank structure skirt is good, the quantity is small, the matching cleft between the piston and air cylinder is smaller, so it is applicable to the high speed engine.(5) In order to
39、 reduce the hot inflation degree of the aluminum metal alloy piston skirt department, some gasoline machine1piston imbeds the steel slice in the piston skirt department or pin.The structure characteristics of the permanent model steel is as the permanent model steel is the low carbon iron nickel met
40、al alloy with33% 36% nickel, its coefficient of expansion is only 1/10 of that of aluminum metal alloy. But pin through the permanent model steel slice and the skirt departments connect with each other and curb the degree of the coefficient of expansion.(6) the gasoline that have is on board, the ce
41、nter line of the piston pin is to deviate the piston center line flat surface, subjected to the main side in the route of travel of efficacy a square of the pressure partial to move the 1-2 mms. This kind of structure can make piston compare in from compress route of travel go to make route of trave
42、l of efficacy mildly from press toward air cylinder of a the noodles transfer to press toward air cylinder of another one side, reducing the sound of knocking the urn. While installing, the direction that this kind of piston pin is partial to place cant pack anti-, otherwise change to pound the dint
43、 and will enlarge, making the skirt department damaged1中 文 翻 译 ：发 动 机 活 塞 连 杆 组 活 塞 详 解活 塞 连 杆 组 由 活 塞 、 活 塞 环 、 活 塞 销 、 连 杆 、 连 杆 轴 瓦 等 组 成 。一、功用：活 塞 的 功 用 是 承 受 气 体 压 力 ，并 通 过 活 塞 销 传 给 连 杆 驱 使 曲 轴 旋 转 ， 从 而 气 缸 里 面 的 吸 气 、 排 气 等 过 程 。 活 塞 顶 部 还 是 燃 烧 室 的 组 成 部 分 。活 塞 的 工 作 条 件 ： 活 塞 在 高 温 、 高 压 、
44、 高 速 、 润 滑 不 良 的 条 件 下 工 作 。 活 塞 直 接 与 高 温 气 体 接 触 ， 瞬 时 温 度 可 达 2 5 0 0 K 以 上 ， 因 此 ， 受 热 严 重 ， 而 散 热 条 件 又 很 差 ， 所 以 活 塞 工 作 时 温 度 很 高 ， 顶 部 高 达 6 0 0 7 0 0 K， 且 温 度 分 布 很 不 均 匀 ； 活 塞 顶 部 承 受 气 体 压 力 很 大 ， 特 别 是 作 功 行 程 压 力 最 大 ，汽 油 机 高 达 3 5 MPa ，柴 油 机 高 达 6 9 MPa ，这 就 使 得 活 塞 产 生 冲 击 ， 并 承 受 侧 压
45、 力 的 作 用 ， 因 此 ， 活 塞 应 有 足 够 的 耐 热 性 ， 要 尽 量 减 小 活 塞 的 受 热 面 ， 加 强 活 塞 的 冷 却 ， 适 当 增 大 传 热 面 ， 使 活 塞 顶 部 的 最 高 温 度 下 降 ， 以 便 保 护 活 塞 头 。 活 塞 在 气 缸 内 以 很 高 的 速 度 ( 8 1 2 m/ s ) 往 复 运 动 ， 且 速 度 在 不 断 地 变 化 ， 这 就 产 生 了 很 大 的 惯 性 力 ， 使1活 塞 受 到 很 大 的 附 加 载 荷 。 活 塞 在 这 种 恶 劣 的 条 件 下 工 作 ， 会 产 生 变 形 并 加 速
46、磨 损 ， 还 会 产 生 附 加 载 荷 和 热 应 力 ， 同 时 受 到 燃 气 的 化 学 腐 蚀 作 用 。 因 此 ， 为 了 减 小 往 复 惯 性 力 ， 必 须 尽 可 能 地 减 轻 活 塞 的 重 量 。 活 塞 是 在 高 温 、 高 压 、 高 速 （ 活 塞 平 均 速 度 可 达 1 0 1 1 1 5 m/ s ） 的 条 件 下 工 作 的 ， 其 润 滑 条 件 较 差 ， 活 塞 与 气 缸 壁 间 摩 擦 严 重 。 为 减 小 摩 擦 ， 活 塞 表 面 必 须 光 滑 、 耐 磨 。要 求 ： ( 1 )要 有 足 够 的 刚 度 和 强 度 ， 传
47、 力 可 靠 ；( 2 )导 热 性 好 ， 耐 高 压 、 耐 高 温 、 耐 磨 损 ；( 3 )质 量 小 ， 重 量 轻 ， 尽 可 能 减 小 往 复 惯 性 力 。铝 合 金 材 料 基 本 上 满 足 上 面 的 要 求 ， 因 此 ， 活 塞 一 般 都 采 用 高 强 度 铝 合 金 ， 但 在 一 些 低 速 柴 油 机 上 采 用 高 级 铸 铁 或 耐 热 钢 也 符 合 要 求 。二 、 构造：活 塞 可 分 为 三 部 分 ， 活 塞 顶 部 、 活 塞 头 部 和 活 塞 裙 部 。 1 . 活 塞 顶 部活 塞 顶 部 承 受 气 体 压 力 ， 它 是 燃 烧 室 的 组 成 部 分 ， 其 形 状 、 位 置 、 大 小 都 和 燃 烧 室 的 具 体 形 式 有 关 ， 都 是 为 满 足 可 燃 混 合 气 形 成 和 燃 烧 的 要 求 ， 其 顶 部 形 状 可 分 为 四 大 类 ， 平 顶 活 塞 、 凸 顶 活 塞 、 凹 顶 活 塞 和 成 型 顶 活 塞 。加 工 最 简 单 的 是 平 顶 活 塞 ， 它 的 顶 部 是 一 个 平 面 ， 结 构 简 单 ， 制 造1起 来 较 容 易 ， 受 热 面 积 小 ， 加 工 简 单 ， 顶 部 应 力 分 布 较 为 均 匀 ， 一 般 用 在 汽