Engine (Engine) - a machine capable of converting other types of energy into mechanical energy, including internal combustion engines (gasoline engines, etc.), external combustion engines (Stirling engines, steam engines, etc.) , electric motors, etc. For example, internal combustion engines usually convert chemical energy into mechanical energy. The engine is not only applicable to power generation device, but also applies to whole machine, including power device (such as gasoline engine, aircraft engine). The engine first appeared in UK, so concept of engine also comes from English language, and its original meaning refers to a kind of "mechanical device that generates energy."
If we consider history of production and development of engines, we can note three stages of development: steam engine, external combustion engine and internal combustion engine.
A steam engine is a reciprocating power machine that converts steam energy (for example, when water is heated in a boiler to produce high temperature and high pressure steam) into mechanical work. The advent of steam engine sparked industrial revolution in 18th century. It was still world's most important prime mover until early 20th century, then gradually gave way to internal combustion engines and steam turbines.
The external combustion engine, that is, its fuel is burned outside engine, was invented by R. Stirling from Scotland in 1816, which is why it is also called Stirling engine. The engine converts thermal energy generated by this combustion into kinetic energy. Watt's improved steam engine is a typical external combustion engine. When a large amount of coal is burned to produce heat energy to heat water into a large amount of water vapor, high pressure is generated, and then this high pressure causes machine to do work, thereby completing conversion of heat energy into kinetic energy.
An internal combustion engine is a kind of power machine, which is a heat engine that directly converts generated thermal energy into power by burning fuel inside machine. There are many types, and conventional gasoline engines and diesel engines are typical internal combustion engines. Less common rocket engines and jet engines used in aircraft are also internal combustion engines.
A motor is a device that converts electrical energy into mechanical energy. It uses energized coils (i.e. stator windings) to create a rotating magnetic field and acts on a rotor (i.e. a closed squirrel-cage aluminum frame) to generate magnetoelectric force torque. Motors are divided into DC motors and motors.AC power supplies depending on different power sources,
The location of engine has a big impact on vehicle performance. For passenger cars, engine layout can be roughly divided into three types: front, mid, and rear. Currently, most models on market use front engines, while mid and rear engines are used in only a few sports cars.
4-cylinder 4-stroke engine, 4 strokes (intake, compression, power, exhaust) of each cylinder are performed in turn, which can ensure that when there are three cylinders in intake, compression or exhaust stroke, there is always one cylinder in power tact, which can provide need for constant power;
2 Engine design
We know that overall structure of a car is divided into four parts: engine, chassis, body and electrical equipment.
Our two most common engines are petrol and diesel engines. Generally speaking, gasoline engines are composed of two main mechanisms and five main systems, namely crank mechanism, valve mechanism, fuel supply system, lubrication and cooling system. system, ignition system and starting system; The diesel engine is composed of two main institutions and four main systems, that is, crank mechanism, gas distribution mechanism, fuel supply system, lubrication system, cooling system and starting system. The diesel engine is compression ignited, no ignition system is required.
2.1 Crank mechanism
The crank mechanism is main moving part of engine to realize duty cycle and complete energy conversion. The main parts of crank mechanism can be divided into three groups: body group, piston rod group and crankshaft flywheel group.
We know that an engine has four strokes: air intake, compression, power stroke, and exhaust. During a stroke, rotational motion of crankshaft is converted into a reciprocating motion of piston due to inertial effect. Generally speaking, a crank mechanism is mechanism by which an engine generates and transmits power. Through it, thermal energy released during the combustion of fuel is converted into mechanical energy.
2.2 Valve mechanism
The engine of a conventional car uses a valve-type gas distribution mechanism. Its function is to regularly open and close intake and exhaust valves of each cylinder according to operating sequence and requirements of engine's duty cycle, so that fresh air enters cylinder and exhaust gases exit the cylinder. Cylinder exhaust.
Two common forms of valve trains
The valve-type camshaft consists of two parts: a valve group and a valve transmission group. The components of each group are related to valve position, camshaft position, and valve drive shape. . All modern automotive engines use overhead valves, meaning intake and exhaust valves are housed in cylinder head and suspended upside down from top of cylinder.
2.3 Fuel supply system
As name implies, this system refers to a device used to supply a combustible mixture. Of course, due to different types of fuel, delivery method will be different. For example, supply of gasoline is carried out based on requirements of engine, and a certain amount and concentration of mixed gas is prepared, which is supplied to cylinder, and exhaust gas after combustion is released from cylinder to atmosphere; at same time, diesel fuel supply is prepared in accordance with requirements of engine. The gas mixture of quantity and concentration is supplied to cylinder, and exhaust gas after combustion is released from cylinder into atmosphere.
2.4 Lubrication system
We know that when engine is running, each moving part affects other part with a certain force, and there is a high-speed relative motion. With relative motion, friction on surface of parts is inevitable and wear is accelerated. Therefore, in order to reduce wear, reduce frictional resistance and extend service life, engine must have a lubrication system. The function of lubrication system is to continuously supply enough clean oil of appropriate temperature to friction surfaces of all transmission parts when engine is running, and form an oil film between friction surfaces to realize fluid friction, thereby reducing friction resistance and reducing energy consumption and reducing wear of machine parts to achieve goal of improving reliability and durability of engine. Lubrication methods include pressure lubrication, splash lubrication and grease lubrication.
2.5 Cooling system
The main function of cooling system is timely dissipation of part of heat absorbed by heated parts to ensure that engine operates at most suitable temperature. The cooling system can be divided into air-cooled system and water-cooled system according to different cooling media. If heat of high-temperature parts of engine is directly dissipated into atmosphere for cooling, it is called an air-cooled system. A device that first transfers heat to cooling water and then dissipates it into atmosphere for cooling is called a water cooling system. Due to uniform cooling of water-cooled system, effect is good and running noise of engine is small, at present, water-cooled system is widely used in automobile engines. 2.6 Starting system
To bring a stationary engine into operation, engine crankshaft must first be rotated by an external force so that piston starts moving up and down, and combustible mixture is sucked into cylinder, and then enters subsequent working cycle in turn. And relying on this external power system is starting system. Nowadays, almost all car engines are started by electric starters. When pinion gear on engine shaft engages with ring teeth on periphery of engine flywheel, electromagnetic torque generated by rotation of engine is transmitted to engine crankshaft through flywheel to start engine. An electric starter is called a starter. It uses a rechargeable battery as a power source, and has advantages of simple structure, convenient operation, fast and reliable starting.
2.7 Ignition system (not required for diesel engine)
Gasoline engine ignition system This is a set of systems that gasoline engines have more than diesel engines. When cylinder is about to finish its compression stroke, it is about to enter power stroke. At this time, an ignition system is needed for timely, accurate and reliable ignition of prepared combustible mixed fuel to ensure engine operation.
Energy is a measure of motion of matter, corresponding to various forms of motion of matter. Energy also has different forms that can be converted into each other, but total remains same. Energy in thermodynamics basically refers to thermal energy and mechanical energy converted from thermal energy. Our car's engine converts chemical energy found in fossil fuels into mechanical energy to drive car.
The birth of internal combustion engine. We divide them into two categories: gas engines and petrol engines with Otto cycle characteristics and diesel engines with Diesel cycle characteristics. Modern gas engines are basically equivalent to gasoline engines. Although design of direct injection gasoline engines has changed, working mechanism is still within Otto cycle. For ease of interpretation, following engines are referred to as gasoline and diesel engines.
But have we ever wondered why gasoline engines need spark plugs? Why can't diesel engines be injected with gasoline? Why is it said that diesel is more powerful and more economical, but driving comfort is not ideal? So, in this article, editor uses a comparative method to interpret principles of operation of gasoline and diesel engines.
At first glance, two types of heat engines differ in way they suck in air and ignite fuel. Although they seem to burn oil and apply force only when piston is at top, moment of combustion is within a few milliseconds. What happened gave two machines a different quality. This is difference between Otto cycle and the Diesel cycle.
Diesel cycle operating status and corresponding p-v diagram
Working status of Otto cycle and corresponding p-v diagram
First, let's talk about Otto cycle on left. As shown in figure above, p is pressure in cylinder, v is volume in cylinder, suction stroke is A-B, piston inhales down, and gas pressure at this time remains almost unchanged; B-C adiabatic compression stroke, piston moves up and compresses gas When pressure increases, piston does work on gas, which consumes mechanical energy and increases internal energy of gas (temperature rises); in C-D isovolume combustion process, gas burns suddenly and pressure rises sharply. At this point, volume is too late to change, so you can put it. It is considered as a constant change in volume, adiabatic power stroke D-E, gas pressure increases and then expands adiabatically to push piston down to do work, and at same time expends its own internal energy on mechanical work, and pressure gradually decreases; E-B isovolumic exhaust process, work At end of stroke, exhaust valve opens, gas pressure drops sharply and volume does not have time to change; in exhaust stroke B-A, piston continues to move up by inertia, while exhaust gas is ejected, and pressure at this time remains unchanged.
C-D-E isobaric combustion diesel cycle is a power stroke. The first stage C-D is an isobaric combustion process. Diesel is on fire. The piston moves under a certain pressure while volume increases. The fuel burns, pushing piston to do work. D-E - adiabatic working stroke. The rest of steps are same as above. Of course, p-v curve in figure is an ideal state, and there are certain differences in actual working conditions. Like a passenger car, a high-speed diesel engine is between two cycles, and combustion process is divided into two stages. , The first half is equal volume combustion, second half is isobaric combustion, which satisfies high speed, and also matches characteristics of classic diesel engines.
Do you know? Diesel is actually more flammable than gasoline.
The reason for long coexistence of gasoline and diesel engines is that there are two types of fuel, gasoline and diesel, so there are two types of internal combustion engines that can make full use of characteristics of different fuels. . This may seem like nonsense, but it also confirms phrase "existence is intelligent."
Gasoline and diesel fuel consist of hydrocarbon compounds consisting of two elements: carbon and hydrogen. Gasoline consists of hydrocarbons with 5-9 carbon molecules, while number of carbon atoms in diesel fuel is 10-20. Because gasoline molecules are smaller than diesel fuel, gasoline has better volatility and a faster burning rate. Faster, but diesel with a long chain structure is more likely tooxidizes, so self-ignition temperature of diesel is lower than that of gasoline.
Diesel is easier to ignite than gasoline? This may seem incomprehensible, but it is true. We compare hydrocarbons with a very ordinary tree, then gasoline is like a pile of sawdust that can be thrown into air and slowly fall down, and diesel fuel is like a toothpick that will fall freely no matter how you throw it; wood chips are difficult to light with a match, but a toothpick is easy to light, but throw sawdust into fire and it instantly turns into fire, and a toothpick can burn for even a few seconds.
Two engines isn't just difference between compression ignition and ignition, it's just beginning.
Because of these differences, two engines also have differences and characteristics.
Gasoline volatilizes faster than diesel, so gasoline can enter cylinder in a mixture state on intake stroke, while diesel is less volatile and difficult to mix, so it can only be injected directly into cylinder before intake stroke. workflow starts.
The auto-ignition point of diesel fuel is lower than that of gasoline, so diesel fuel can ignite spontaneously in high temperature and high pressure cylinders; if compression ignition is used in gasoline engines, they must have higher pressures and thus higher temperatures to ignite. , but since gasoline volatilizes easily, it will absorb a lot of heat when evaporating, which again increases difficulty of compression ignition, so this is most suitable way to ignite with a spark plug.
Gasoline burns faster than diesel fuel, so it is too powerful to put gasoline in an environment with high temperature and high pressure. Combustion spreads in form of "waves", which avoids effects of deflagration, and diesel fuel several places at same time in air with high temperature and high pressure with formation of a flame, that is, in form of deflagration (similar to “knock” of gasoline engines) The operating condition is relatively heavy, and therefore diesel burns slowly, although combustion starts violently, burning time is even longer than that of a gasoline engine.
A gasoline engine is an engine that uses gasoline as fuel. The advantages are high speed, simple structure, light weight, low cost, stable operation, convenient use and maintenance. The disadvantage is that thermal efficiency is lower than diesel, fuel consumption is higher, ignition system is more complicated than diesel, and reliability and serviceability are not as good as diesel.
A diesel engine is an engine that uses diesel fuel to release energy. The advantages are high power and good economic performance, and it is also suitable for truck use. The disadvantage is that cost is high, vibration and noise are large, and it is difficult to start car in cold in winter..
After mixed gas in gasoline engine is ignited, it instantly burns and releases energy, so cycle can be repeated many times per unit time, and high power can be output at high speed, so it has a small size. and light weight With higher performance and faster response speed, wide speed range can also improve feeling of control. However, compression ratio of a gasoline engine is often half that of a diesel engine, and temperature and pressure in cylinder during power stroke is much lower than that of a diesel engine, so thermal efficiency is relatively low. which is commonly known as "fuel consumption".
After fuel is injected into diesel engine, it takes a certain time to burn it, so it is advisable that fuel burns completely at a low speed to ensure high torque. To withstand high pressure and high torque in cylinder, diesel engine cylinder and piston rod parts are stronger than gasoline engines, so they are heavier than gasoline engines. But also due to characteristics of high compression ratio and low speed, diesel engines can better convert heat into kinetic energy, so diesel engines have better thermal efficiency, that is, better fuel consumption. This is why cars and racing cars usually use gasoline engines, while larger vehicles like buses and trucks use diesel engines.
With development of technology, ride and displacement of diesel engines have been greatly improved. The process of manufacturing cylinder block from high-strength aluminum reduces weight of engine. Exhaust aftertreatment and particle recovery effectively reduce exhaust gas pollution. The high-pressure common rail injection system and lower compression ratio (compared to traditional diesel engines) effectively suppress noise; use of balancer shafts increases ride comfort; Variable section VGT turbines and intercoolers increase engine power, and many excellent designs are gradually being introduced into car. Based on car (click to enter: analysis of technology of an efficient, powerful and environmentally friendly passenger car diesel engine), diesel engine has capital to compete with gasoline engine, and its low carbon emissions and excellent torque at low speed have been chosen by many SUVs and even cars.
In Europe, share of diesel vehicles in passenger cars has reached 40%, while domestic diesel engines are mainly used in SUV models. More recently, diesel vehicles of domestic own brands have been launched. But current quality of domestic diesel fuel is not good enough, as a result of which diesel engines are not accepted by all.seriously in China. The main problems are that cetane number is not high enough (poor combustion), sulfur content is too high (damaging engine parts and increasing exhaust pollution), too many polycyclic aromatic hydrocarbons (that is, too many impurities that will cause coking and carbon deposition, if combustion is bad)) etc., if quality of diesel fuel in China can be improved, I believe that in face of sharp rise in oil prices and environmental degradation, Chinese will gradually adopt diesel cars.
4Introduction to general vehicle parameters
The most common engine parameters are displacement, compression ratio, horsepower in liters, maximum power, maximum torque, maximum power, etc. What do they mean?
Displacement is sum of displacements of all cylinders. We know that each cylinder has top dead center and bottom dead center, and volume between top dead center and bottom dead center is stroke volume of cylinder, and stroke volume is sum of number of cylinders and volume of cylinder.
4.2 Compression ratio
Compression ratio is compression ratio of engine mixture, expressed as ratio of total volume of cylinder before compression to volume of cylinder after compression (that is, volume of combustion chamber).
The higher compression ratio, more powerful engine. Typically, low pressure compression ratio is typically below 10 and high pressure compression ratio is above 10. The highest compression ratio known for gasoline engines has been as high as 12:1.
Normal engine operating temperature is 80-110°C. Too high a compression ratio can cause spontaneous combustion and pre-ignition of gasoline, causing detonation, weakening engine and damaging mechanical components. Therefore, it is very important to maintain normal engine operating temperature while increasing compression ratio.
4.3 Number of cylinders and arrangement of cylinders
"L4", "V6", "V8", and "W12" refer to location and number of engine cylinders. L: in-line; V: V-shaped; W: W-shaped; H: horizontally opposed engine; number indicates number of cylinders; L4 stands for inline 4-cylinder engine. The in-line arrangement is currently most widely used cylinder arrangement, especially in engines with a displacement of less than 2.5 liters.
4.4 max power
The physical meaning of power is work done per unit of time. Engine power output is closely related to speed. As speed increases, so does power of engine. There will be a downward trend, so there will be a peak, which is maximum power of engine, which mainly depends on size of engine cylinder displacement, amount of fuel burned and engine speed.
4.5 maximum power
Horsepower and power are actually same thing, but traditionally people like to express power in terms of horsepower, and letter is PS. However, kilowatt (KW) values are now also present. The conversion ratio between them is as follows: 1PS=0.735 kW.
Power per liter is an important metric for evaluating engine performance. It represents power generated by cylinder displacement per liter and reflects technical level of engine. The more power per liter, higher utilization factor of engine weight, relatively speaking, smaller engine and less material it saves. Its unit is kW/L, and our usual method of calculation is to divide its cylinder displacement by its maximum power.
4.7 Maximum Torque
Maximum torque is maximum torque that crankshaft can produce when engine is running, and vehicle's driving force is closely related to it. The more torque, more "power" engine has and better car's climbing ability, starting speed and acceleration. The maximum torque only exists at a certain speed or within a certain range of speeds, and this range is speedb or speed range indicated with designation of maximum torque. Peak torque usually occurs in mid to low rpm range of engine, but as speed increases, torque will decrease. The unit of torque is newton meter (Nm).
5 brands and manufacturers of engines
5.1 Brand of gasoline engine
Undoubtedly, Japanese company Mitsubishi almost monopolized supply of gasoline engines for all cars of its own brand that cannot produce their own engines. Mitsubishi Corporation, which has a small market share in China's complete vehicle market, established Aerospace Mitsubishi in Shenyang, Liaoning Province in 1997 and Dong'an Mitsubishi in Harbin, Heilongjiang Province in 1998 with Mr. Yang's matchmaking Rong, a giant in Chinese auto industry at time Manufactured medium and small petrol engines for Hafei, Southeast, Brilliance and other companies of time. With emergence of independent brands such as Chery, Geely, Brilliance, and BYD around 1999 when they were unable to produce their own engines at start of their construction, performance of these two engine companies invested by Mitsubishi in China grew by leaps and bounds. and they made a lot of money for less money.
According to incomplete statistics, models using Dongan Mitsubishi engines include: BYD F3, Brilliance Junjie, Southeast Lancer, Lingyue, Xiwang, Hafei Racing Horse, Saibao, Zotye 5008, Fengxing Jingyi, Changfeng Feiteng... using Shenyang Aerospace Mitsubishi. Engine models include: BYD F6, Brilliance Zunchi, Junjie, Jinbei Hiace, Chery Dongfangzi, Ford Transit, JAC Binyue, Shanghai Yinglun TX4, Emgrand EC8, Southeast Lingyue, Junge, Galant, JMC Landwind, Haima 3, Liuqi Fengxing MPV, Changfeng Leopard . , Great Wall Haval, Jiayu, Huatai Terraca, Beiqi Yusheng, Cavaliers, Foton Monpac, Scenic, Zhengzhou Nissan (Weibo) Odin, ZTE Infinity, Weihu, Suguang Aolong, Qi Win...
Diesel engine 5.2 Brand
When it comes to light duty diesel engines, Isuzu is clear king. Back in 1984 and 1985, Japanese diesel engine and commercial vehicle giant founded Qingling Motors and Jiangling Motors in Chongqing, Sichuan and Nanchang, Jiangxi, respectively, and began manufacturing Isuzu pickup trucks, light trucks, and 4JB1 engines. With shutdown of passenger cars such as Ford Transit and Foton Scenic, Isuzu engines have found a blue ocean in passenger car market. Now almost all diesel engines used in pickup trucks, light trucks and light buses in China are purchased from Isuzu or manufactured using Isuzu technology.
In terms of high power diesel engines, Cummins from USA is leader. This American independentThe engine manufacturer has set up four complete truck-only companies in China: Dongfeng Cummins, Xi'an Cummins, Chongqing Cummins, and Foton Cummins. Heavy truck manufacturers such as MAN, bus companies such as Yutong, Jinlong, Youth, and Zhongtong, and construction machinery companies such as Sany Heavy Industry, Zoomlion and XCMG. It can be said that Cummins has almost monopolized high-end heavy-duty diesel engine market in China.
EFI 5.3 system
To meet China's ZF's increasingly stringent emissions requirements, all domestically produced vehicles must be equipped with EFI systems. Germany's Bosch, America's Delphi and Japan's Denso (owned by Toyota Group) have nearly monopolized all Chinese EFI market shares, among which Germany's Bosch has largest market share of over 60%. From domestic brands to foreign brands, from cars to trucks, from gasoline-powered vehicles to diesel-powered vehicles, every time Chinese consumers buy a car, they will contribute thousands of yuan in profits to above three foreign companies.
5.4 Engine design
Austrian AVL, German FEV and British Ricardo are today three largest independent engine companies in world. Together with Italian diesel engine specialist VM, these four companies monopolize development of engines of domestic independent brands. .
Currently, AVL's main customers in China are: Chery, Weichai, Xichai, Dachai, Shangchai, Yunnei, etc.
The Italian company VM, located in same city as Ferrari, Lamborghini and Maserati, has supplied engines for Range Rover, Rover 800 and Alfa Romeo in last century. Since 2004, Jiangling, Huatai, Changfeng, Great Wall and SAIC have successively acquired VM's diesel engine manufacturing technology and key production equipment and started to produce their own diesel engines. The German company FEV started selling engine technology to Guangxi Yuchai back in 1980. At present, its main customers in China are: FAW, SAIC, Brilliance, Landwind, Yuchai and Yunnei. British Ricardo began supplying diesel engines for London buses and French Citroen back in 1930s. Major achievements in recent years include development of DSG transmissions for Audi R8 and Bugatti Veyron, BMW's help in optimizing K1200 series motorcycle engines, McLaren's help in developing its first engine M838T and so on. Currently, Ricardo's customers in China are: FAW, SAIC, Great Wall, Lifan, etc.
World's 6 Best Engines 2016
The professional editors of Ward's AutoWorld choose "Top Ten Engines" of year each year. These strict selection criteria areComparative data such as engine noise, vibration and comfort (NVH), fuel efficiency and technological innovations are collected. . The top ten engines must be equipped with production models, and price of models will gradually increase to no more than $61,000. These models must also be sold in North American market, but due to its popularity and authority in world, every time results are published, attract everyone's attention.
In this selection, all power systems of all Volkswagen Group brands, including Audi and Porsche, were disqualified due to Volkswagen diesel emission fraud incident. This year's Ward Top Ten includes six gasoline engines, one diesel engine and three hybrid systems. Among them, European and American brands occupy half country, and Asian brands are slightly weaker. Of course, since judges are all North American, their personal preferences cannot be ignored.
3.0-litre turbocharged BMW inline-6 petrol engine
BMW 340i GM 3.6L V6 petrol engine with direct injection
Cadillac ATS General Purpose 1.5L Direct Injection Inline-4 Petrol + 120kW Electric Motor
5.2L Chevrolet Volt Dafort V8 Petrol
Ford Mustang Shelby GT350 Hyundai 2.0L Direct Injection Inline-4 Petrol + 50kW Electric Motor
Hyundai Sonata plug-in hybrid with 3.5-litre Nissan V6 petrol engine
Nissan Maxima Fiat/Chrysler 3.0L V6 Turbo Diesel
Subaru's 2.0L turbo horizontally opposed 4-cylinder petrol engine
Subaru WRX Toyota 1.8L Inline-4 Petrol + 53kW Electric Motor
Toyota Prius Volvo 2.0-litre Supercharged Inline-4 Petrol
Volvo XC90 BMW 3.0-litre turbocharged inline 6-cylinder petrol engine.
Due to Volkswagen emissions scandal, his group was disqualified from competition, so Audi's 3.0-litre supercharged petrol engine could not compete, making BMW's 3.0-litre turbocharged petrol unit under codenamed B58 an easy win. Here comes jackpot. In fact, BMW has always been a frequent guest at Ward Engine Awards. In recent years, N55, N20 and B38 awards reflect the Ward judges' recognition of turbocharged BMW engines.
BMW 3.0L turbocharged inline 6-cylinder petrol engine↓
This time code name for award-winning engine is B58. Anyone with even slightest understanding of BMW's powertrain can tell from codename that this is a product of BMW's engine modularity strategy. It's roughly a patchwork of two B38.Up engines, it's a turbocharged inline 6-cylinder petrol engine. The engine uses a larger twin-scroll turbocharger and a higher compression ratio than N55 engine. Equipped with this engine, BMW 340i responds aggressively to gas pedal, delivering impeccable response and balance.
Cylinder/cylinder head material Aluminum alloy/Aluminum alloy
Diameter x stroke (mm)82x94.6
Progressive power (PS/L)107
Equipped Models 2016 BMW 340i
Fuel consumption city/constant speed (l/100 km)10.68/7.12
Notes.Fuel consumption test complies with EPA standard
Link: World's Top Ten Engines 2016http://auto.sohu.com/20160129/n436368805.shtml