Use

The working principle

The internal combustion engine burns fuel within th cylinders and converts the expanding force of the combustion or “explosion” into rotary force used to propel the vehicle.

内燃机在气缸中燃烧燃料，将燃烧带来的推动力或爆炸作用转变成（部件）的旋转运动，来驱动车辆。

Internal and external combustion engine

Internal combustion

内燃机

Gasoline engines

汽油机

Diesel engines 柴油机

Compression-ignition engine

压缩点燃式发动机

Spark-ignition engine

火花点燃式发动机

Internal and external combustion engine

Two-and four-stroke engines

four-stroke enginesToday, internal combustion engines in cars, trucks, motorcycles, aircraft, construction machinery and many others, most commonly use a four-stroke cycle. The four strokes refer to intake, compression, combustion (power), and exhaust strokes that occur during two crankshaft rotations per working cycle of the gasoline engine and diesel engine.The cycle begins at Top Dead Center (TDC), when the piston is farthest away from the axis of the crankshaft. A stroke refers to the full travel of the piston from Top Dead Center (TDC) to Bottom Dead Center (BDC). 1. INTAKE stroke: On the intake or induction stroke of the piston , the piston descends from the top of the cylinder to the bottom of the cylinder, reducing the pressure inside the cylinder. A mixture of fuel and air is forced by atmospheric (or greater) pressure into the cylinder through the intake port. The intake valve(s) then close.

Two-and four-stroke engines2. COMPRESSION stroke: With both intake and exhaust valves closed, the piston returns to the top of the cylinder compressing the fuel-air mixture. This is known as the compression stroke.3. POWER stroke.: While the piston is close to Top Dead Center, the compressed air–fuel mixture is ignited, usually by a spark plug (for a gasoline or Otto cycle engine) or by the heat and pressure of compression (for a diesel cycle or compression ignition engine). The resulting massive pressure from the combustion of the compressed fuel-air mixture drives the piston back down toward bottom dead center with tremendous force. This is known as the power stroke, which is the main source of the engine's torque and power.

Two-and four-stroke engines

4. EXHAUST stroke: During the exhaust stroke, the piston once again returns to top dead center while the exhaust valve is open. This action evacuates(排出） the products of combustion from the cylinder by pushing the spent fuel-air mixture through the exhaust valve(s).

Liquid-cooled and air-cooled engines

Most modern internal combustion engines are cooled by a closed circuit(回路） carrying liquid coolant （冷却液） through channels in the engine block and cylinder head, where the coolant absorbs heat, to a heat exchanger or radiator（散热器）  where the coolant releases heat into the air. Thus, while they are ultimately cooled by air, because of the liquid-coolant circuit they are known as water-cooled. In contrast, heat generated by an air-cooled engine is released directly into the air. Typically this is facilitated with metal fins（散热片）  covering the outside of the cylinders which increase the surface area that air can act on.

Liquid-cooled and air-cooled engines

往复式发动机和转子式发动机

转子式发动机The most successful rotary engine is the Wankel engine. Developed by the German engineer Felix Wankel in 1956, it has a disk that looks like a triangle with bulging sides rotating inside a cylinder shaped like a figure eight with a thick waist. The engine runs on a four-stroke cycle. The Wankel engine has 48% fewer parts and about a third the bulk and weight of a reciprocating engine. Its main advantage is that advanced pollution control devices are easier to design for it than for the conventional piston engine. Another advantage is that higher engine speeds are made possible by rotating instead of reciprocating motion.

Lubrication System

往复式发动机和转子式发动机

Spark-ignition and compression-ignition engines

Automobile Engine

Intermittent combustion means that the combustion within the engine starts and stops.

They are commonly divided into continuous-combustion engines and intermittent-combustion engines. In the first type (e.g., jet engines) fuel and air flow steadily into the engine, where a stable flame is maintained for continuous combustion. In the second (e.g., gasoline – reciprocating-piston engines), discrete quantities of fuel and air are periodically ignited.

Automobile Engine

Intermittent combustion means that the combustion within the engine starts and stops.

间断燃烧意味着燃烧在发动机启动和停止间进行。

Intermittent combustion means that the combustion within the engine starts and stops.

Robert Stirling was the Scottish inventor of the first practical example of a closed cycle air engine in 1816,

by the location of cylinders

by the location of cylinders

Crank mechanism

Automobile Engine

A carburetor (American spelling), carburettor, or carburetter (Commonwealth spelling) is a device that blends air and fuel for an internal combustion engine. It is sometimes shortened to carb in North America and the United Kingdom.

Automobile Engine

The internal combustion engine burns fuel within the cylinders and converts the expanding force of the combustion or “explosion” into rotary force used to propel the vehicle.

内燃机在汽缸内燃烧燃料，并将燃烧的推动力或是爆炸力转换成旋转力驱动汽车。

Engine and driving wheels

Valvetrain配气机构Valvetrain is an term used to describe the mechanisms and parts which control the operation of the valves. The valvetrain consists of valves, rocker arms, pushrods, and camshaft(s). Valvetrain opening/closing and duration, as well as the geometry of the valvetrain, controls the amount of air and fuel entering the combustion chamber at any given point in time. Timing for open/close/duration is controlled by the camshaft that is synchronized( 一致） to the crankshaft by a chain or belt.

Intermittent combustion and continuous combustion

enginesThe internal combustion engine burns fuel within the cylinders and converts the expanding force of the combustion or “explosion” into rotary force used to propel the vehicle.

内燃机在汽缸内燃烧燃料，并将燃烧的推动力或是爆炸里转换成旋转力驱动汽车。

Review1 It is well-known that the automobile is composed of four sections such as engine, chassis, body and electrical system.发动机、底盘、车身和电气系统。

2 why the engine is called the heart of a vehicle?

Because the engine is used to supply power for an automobile.

Review3 Internal combustion engines find wide application in modern automobiles. True or False.True

4 What is the operating principle of ICE?

ICE burns fuel within the cylinders and converts the expanding force of the combustion or “explosion” into rotary force used to propel the vehicle.

Ignition System点火系统Collect more information to further your understanding , esp. on the sentences " The battery provides current to produce the spark. Once the current leaves its source, it flows in a definite path to the cylinders.”

assignment 12 Internal combustion engines commonly use a four-stroke circle. Please narrate its power stroke.While the piston is close to Top Dead Center, the compressed air–fuel mixture is ignited, usually by a spark plug (for a gasoline or Otto cycle engine) or by the heat and pressure of compression (for a diesel cycle or compression ignition engine). The resulting massive pressure from the combustion of the compressed fuel-air mixture drives the piston back down toward bottom dead center with tremendous force. This is known as the power stroke.

assignment 13 Translate the underlined sentences in the article.

Unlike the conventional gasoline engine, it has no spark plugs. The heat of compression ignites the fuel. A piston coming up on the compression stroke compresses the air in the cylinder until it reaches an extremely high temperature. At this time, fuel is injected into the cylinder under high pressure. The temperature within the cylinder ignites the fuel. The expanding gases of the burning fuel force the piston down on its power stroke . 与传统汽油机不同的是，它没有火花塞，是靠摩擦产生的热量点燃燃料。火花塞在压缩冲程中上行压缩气体使气缸温度升至很高，高压将燃料喷入气缸，高温将燃料点燃。燃烧导致的气体膨胀推动活塞下行进入做功冲程。

The Automobile Components

Frame1 What is the function of frame?

2 What’s the purpose of rubber pads?

3 The frame is supported on__________ by means of ______________. The whole assembly is called__________.

dampingThe action of a substance or of an element in a mechanical or electrical device that gradually reduces the degree of oscillation, vibration, or signal intensity, or prevents it from increasing. For example, sound-proofing technology dampens the oscillations of sound waves. Built-in damping is a crucial design element in technology that involves the creation of oscillations and vibrations

Frame

FrameThe engine is mounted on the frame with rubber pads which absorb vibrations and also provide damping of these vibrations. The frame is supported on wheel axles by means of springs. This whole assembly is called the chassis.

frame 车架rubber pad 橡胶衬垫damping 阻尼wheel axles 轮轴Chassis 底盘

Suspension system悬架系统What is the function of the suspension system ?悬架系统The function of the suspension system is to absorb vibrations due to the up and down motion of wheels, caused by the irregularities in the road surface.

Power train传动系统The power train carries the power the engine produces to the car wheels, and it consists of _____________The clutch( 离合器）， transmission( 变速箱）， driveshaft( 驱动轴）， differential( 差速器） and rear axle( 后桥）

Steering System

Braking System

Automobile Engine

压缩比：压缩前气缸中气体的最大容积与压缩后的最小容积之比，国标以 ε 表示，也等于气缸总容积与燃烧室容积的比值。汽油机在运转时，吸进的是汽油与空气混合气，压缩比越大，压缩终了的混合气的压力和温度就越高，混合气中的汽油分子就能气化得更完全，燃烧也更迅速更充分，因而发动机发出的功率越大，经济性越好，排气质量也能相应得到改善。The COMPRESSION RATIO of an engine is a measurement  of  how  much  the  air-fuel  charge  is compressed in the engine cylinder. It is calculated by dividing the volume of one cylinder with the piston at BDC by the volume with the piston TDC.

Automobile Engine

压缩比：压缩前气缸中气体的最大容积与压缩后的最小容积之比，国标以 ε 表示，也等于气缸总容积与燃烧室容积的比值。汽油机在运转时，吸进的是汽油与空气混合气，压缩比越大，压缩终了的混合气的压力和温度就越高，混合气中的汽油分子就能气化得更完全，燃烧也更迅速更充分，因而发动机发出的功率越大，经济性越好，排气质量也能相应得到改善。The smaller engines were commonly air-cooled and located at the rear of the vehicle; compression ratios were relatively low. The 1970s and '80s saw an increased interest in improved fuel economy which brought in a return to smaller V-6 and four-cylinder layouts, with as many as five valves per cylinder to improve efficiency.