蘇A's 痞客幫

The engine is controlled by a computer based ECU (engine control unit) which makes use of a range of sensors and actuators to operate the engine. The ECU controls all aspects of the engine performance with the exception of the cable operated 'butterfly' throttle which is operated via the accelerator pedal. The ECU makes use of the following sensors: Throttle position sensor This is a rotary angle position sensor fitted to the throttle butterfly shaft Manifold air pressure sensor This sensor is connected to the inlet manifold by a piece of flexible tubing and measures the absolute pressure in the inlet manifold. (Inlet manifold pressure is at its lowest when the throttle is closed and engine revs are high.) Inlet air temperature sensor Installed in the inlet manifold, this sensor reports the temperature of air entering the engine. Engine temperature sensor Installed in the vehicle radiator, this sensor reports the temperature of the engine coolant. Crank shaft position sensor This sensor is used to determine the angle of the crankshaft and engine speed. The crankshaft pulley includes a series of signal 'teeth' and one indexing 'toothless' region which is read by an inductive pulse pickup. Lambda sensor This sensor, installed in the exhaust pipe, measures the oxygen content of the exhaust gases. Road speed sensor The car speedometer (driven by a cable from the gearbox) also includes an output which informs the ECU of the car's road speed. Fuel octane plug The ECU must be informed of the octane rating of the fuel used. A selector plug is provided that is adjusted by the car user. Air conditioning switch The ECU takes an input from the cabin air conditioning (AC) system to know when the AC system is active.

Based on the inputs from the above sensors the ECU controls the following actuators and systems: Ignition The ECU controls the timing of the ignition spark provided to each cylinder. On some models a direct ignition system (DIS) is used in place of a single ignition coil and distributor. Fuel injection Each cylinder has its own fuel injector which is opened for a short time to introduce petrol into the intake manifold. Idle air control When the engine is idling (accelerator not depressed) the throttle butterfly is fully closed. To control the engine idle speed a small motor in the throttle body is used to pass air into the engine effectively by-passing the throttle butterfly. Air conditioning override In cases where the engine is expected to deliver near maximum power the ECU can switch off the air conditioning clutch to remove the load the AC system places on the engine. Check engine light Situated in the instrument panel the orange 'check engine' lamp is illuminated when the engine is not running. It will also illuminate whilst the engine is running if an engine engine error (such as a malfunctioning sensor) occurs.

    The engine block is the basic frame of the engine. All other engine parts either fit inside it or fasten to it. It holds the cylinders, water jackets, and oil galleries.The engine block also holds the crankshaft, which fastens to the bottom of the block. The camshaft also fits inside the block, except on overhead-cam engines (OHC). In most cars, this block is made of gray iron, or an alloy (mixture) of gray iron and other metals, such as nickel or chromium. Engine blocks are castings. The engine block is the basic frame of the engine. All other engine parts either fit inside it or fasten to it. It holds the cylinders, water jackets, and oil galleries.The engine block also holds the crankshaft, which fastens to the bottom of the block. The camshaft also fits inside the block, except on overhead-cam engines (OHC). In most cars, this block is made of gray iron, or an alloy (mixture) of gray iron and other metals, such as nickel or chromium. Engine blocks are castings. 氣缸體是發動機的基本框架。 發動機的其他零件都安裝在它裡面或者固定在它上。 缸體裡有氣缸，水套和油道。  曲軸也固定在氣缸體底部。 除了頂置凸輪(OHC)發動機以外，凸輪軸都安裝在氣缸體裡面。 在大多數汽車裡，氣缸體由灰鑄鐵或者一種灰鑄鐵和其他金屬的合金(混合物)做成，例如鎳或鉻。氣缸體是鑄件。 Some engine blocks, especially those in smaller cars, are made of cast aluminum. This metal is much lighter than iron. However, iron wears better than aluminum. Therefore, the cylinders in most aluminum engines are lined with iron or steel sleeves. These sleeves are called cylinder sleeves. Some engine blocks are made entirely of aluminum. Some engine blocks, especially those in smaller cars, are made of cast aluminum. This metal is much lighter than iron. However, iron wears better than aluminum. Therefore, the cylinders in most aluminum engines are lined with iron or steel sleeves. These sleeves are called cylinder sleeves. Some engine blocks are made entirely of aluminum. 有些氣缸體，特別是在小汽車裡的那些，都是由鋁做成的。  這種金屬比鑄鐵輕得多。 但是，鑄鐵的耐磨性比鋁好。  因此，在大多數鋁製發動機的氣缸內鑲有鑄鐵或者鋼的軸套。 这些轴套叫做气缸套。 這些軸套叫做氣缸套。而有些氣缸體完全由鋁做成。

The cylinder head fastens to the top of the block, just as a roof fits over a house. The underside forms the combustion chamber with the top of the piston. The most common cylinder head types are the hemi, wedge, and semi-hemi.All three of these terms refer to the shape of the engine's combustion chamber. The cylinder head carries the valves, valve springs and the rockers on the rocker shaft, this part of the valve gear being worked by the push-rods. Sometimes the camshaft is fitted directly into the cylinder head and operates on the valves without rockers. This is called an overhead camshaft arrangement. Like the cylinder block, the head is made from either cast iron or aluminum alloy. The cylinder head fastens to the top of the block, just as a roof fits over a house. The underside forms the combustion chamber with the top of the piston. The most common cylinder head types are the hemi, wedge, and semi-hemi. All three of these terms refer to the shape of the engine's combustion chamber. The cylinder head carries the valves, valve springs and the rockers on the rocker shaft, this part of the valve gear being worked by the push-rods. Sometimes the camshaft is fitted directly into the cylinder head and operates on the valves without rockers. This is called an overhead camshaft arrangement. Like the cylinder block, the head is made from either cast iron or aluminum alloy. 氣缸蓋固定在氣缸體的頂上，正像屋頂套在一所房子上面一樣。氣缸蓋下面與活塞頂上的空間形成燃燒室。 最常見的氣缸蓋類型是半球形，楔形和準半球形。  這三種說法都是指燃燒室的形狀。 氣缸蓋攜帶閥門，氣門彈簧和在搖臂桿上的搖臂，這部分的氣門傳動機構通過推桿工作。有時，凸輪軸直接安裝在氣缸蓋上並且不用搖臂控制閥門工作。 這被叫為頂置凸輪軸裝置。 像氣缸體一樣，氣缸蓋是由鑄鐵或者鋁合金製成。

    The cylinder head is attached to the block with high-tensile steel studs. The joint between the block and the head must be gas-tight so that none of the burning mixture can escape. This is achieved by using cylinder head gasket. This is a sandwich gasket, ie a sheet of asbestos between two sheets of copper, both these materials being able to withstand the high temperature and pressures within the engine. The cylinder head is attached to the block with high-tensile steel studs. The joint between the block and the head must be gas-tight so that none of the burning mixture can escape. This is achieved by using cylinder head gasket. This is a sandwich gasket, ie a sheet of asbestos between two sheets of copper, both these materials being able to withstand the high temperature and pressures within the engine. 氣缸蓋與氣缸體用高強度的鋼螺栓縛連結。 氣缸體和氣缸蓋之間的連接必須密封以便沒有燃燒的混合氣體洩漏。 這通過使用氣缸蓋襯墊實現。 這是一個夾層襯墊，即在兩片銅之間放一片石棉，這兩種材料都能禁得住在發動機內的高溫和高壓。

The oil pan is usually formed of pressed steel. The oil pan and the lower part of the cylinder block together are called the crankcase; they enclose, or encase, the crankshaft. The oil pump in the lubricating system draws oil from the oil pan and sends it to all working parts in the engine. The oil drains off and runs down into the pan. Thus, there is constant circulation of oil between the pan and the working parts of the engine. The oil pan is usually formed of pressed steel. The oil pan and the lower part of the cylinder block together are called the crankcase; they enclose, or encase, the crankshaft. The oil pump in the lubricating system draws oil from the oil pan and sends it to all working parts in the engine. The oil drains off and runs down into the pan. Thus, there is constant circulation of oil between the pan and the working parts of the engine. 油底殼通常由鋼沖壓形成。 油底殼和氣缸體的下半部分一同被叫做曲軸箱；他們把曲軸封閉起來。 潤滑系統中的機油泵從油底殼抽取油並把油輸送到發動機內全部正在工作的部分。 機油流出後又流回油底殼。因而在油底殼和發動機工作零件之間有機油不斷流動循環。

To withstand the heat of the combustion chamber, the piston must be strong. It also must be light, since it travels at high speeds as it moves up and down inside the cylinder. The piston is hollow. It is thick at the top where it take the brunt of the heat and the expansion force. It is thin at the bottom, where there is less heat. The top part of the piston is the head , or crown . The thin part is the skirt The sections between the ring grooves are called ring lands.

The piston crown may be flat , concave ,dome or recessed . In diesel engine , the combustion chamber may be formed totally or in part in the piston crown , depending on the method of injection . So they use pistons with different shapes.

piston rings fit into ring grooves near the of the piston. In simplest terms, piston rings are thin, circular pieces of metal that fit into grooves in the tops of the pistons.

In modern engines ,each piston has three rings. (Piston in older engines sometimes had four rings, or even five.) The ring’s outside surface presses against the cylinder walls. Rings provide the needed seal between the piston and the cylinder walls. That is, only the rings contact the cylinder walls. The top two rings are to keep the gases in the cylinder and are called compression rings. The lower one prevents the oil splashed onto the cylinder bore from entering the combustion chamber , and is called an oil ring. Chrome-face cast-iron compression rings are commonly used in automobile engines. The chrome face provide a very smooth , wear-resistant surface.

During the power stoke , combustion pressure on the combustion rings is very high. It causes them to untwist . Some of the high-pressure gas gets in back of the rings. This force the ring face into full contact with the cylinder wall. The combustion pressure also holds the bottom of the ring tightly against the bottom of the ring groove. Therefore , high combustion pressure causes a tighter seal between the ring face and the cylinder wall.

The piston pin holds together the piston and the connecting rod . This pin fits into the piston pin holes and into a hole in the top end of the connecting rod. The top end of is much smaller than the end that fits on the crankshaft . This small end fits inside the bottom of the piston . The piston pin fits through one side of the piston , through the small end of the rod , and then through the other side of the piston . It holds the rod firmly in place in the center of the piston. Pins are made of high-strengh steel and have a hollow center . Many pins are chrome-plated to help them wear better.

high-strength steel . It transmits and motion from the piston to the crankpin on the crankshaft . The connecting rod little end is connected to the piston pin . A bush made from a soft metal , such as bronze , is used for this joint . The lower end of the connecting rod fits the crankshaft journal . This is called the big end . For this big-end bearing , steel-backed lead or tin shell bearing are used . These are the same as those used for the main bearings . The split of the big end is sometimes at an angle , so that it is small enough to be withdrawn through the cylinder bore . The connecting rod is made from forged alloy steel .

The crankshaft , in conjunction with the connecting rod , coverts the reciprocating motion of the piston to the rotary motion needed to drive the vehicle . It is usually made from carbon steel which is alloyed with a small proportion of nickel .The main bearing journals fit into the cylinder block and the big end journals align with the connecting rods .At the rear end of the crankshaft is attached the flywheel , and at the front end are the driving whells for the timing gears , fan , cooling water and alternator .

The throw of the crankshaft , the distance between the main journal and the big end centers , controls the length of the stroke . The stroke is double the throw , and the stroke-length is the distance that the piston travels from TDC to BDC and vice versa .

Camshaft Case

 

              

PS：網路上找來的，中文翻譯部分應該還要再修飾一下。