Internal combustion engine is a kind ofPower machineryBy burning the fuel inside the machine and releasing itheat energyDirectly converted to powerThermal engine。In a broad sense, internal combustion engines not only includeReciprocating piston internal combustion engine、Rotary piston engineandFree piston engine, including rotary vane typeJet engineHowever, the internal combustion engine usually refers to the piston type internal combustion engine.In the past, piston type internal combustion engines were the most common.The piston internal combustion engine mixes fuel and air and burns them in its cylinder. The heat released makes the cylinder produce high-temperature and high-pressure gas.Gas expansionPush the piston to do work, and then passCrank connecting rod mechanismOr other institutions willMechanical workOutput to drive the driven machinery.The common ones areDiesel engineandgasoline engine, by settinginternal energyConvert tomechanical energy, viaWorkChange internal energy.[1]
Piston internal combustion engine originated from Dutch physicistsHuygensThe research on obtaining power by powder explosion has not been successful because of the difficulty in controlling the combustion of powder.In 1794, an Englishman named Stritt proposed to obtain power from the combustion of fuel and put forward the concept of mixing fuel and air for the first time.In 1833, the Englishman Wright put forward the design of directly using combustion pressure to push the piston to do work.[2]
In the mid-19th century, scientists perfected the technology of burning gas,gasolineAnd diesel, etc.This laid the foundation for the invention of internal combustion engine.Since the advent of piston internal combustion engine in the 1960s, it has been a relatively perfect machine through continuous improvement and development.itthermal efficiencyHigh power, wide range of power and speed, convenient matchingmaneuverabilityGood, so it has been widely used.All kinds of automobiles, tractors, agricultural machinery, construction machinery, small mobile power stations andwar chariotAll of them are powered by internal combustion engines.Marine merchant ships, inland ships and conventional ships, as well as some small aircraft, are also propelled by internal combustion engines.The number of internal combustion engines in the world ranks first in power machinery, which plays a very important role in human activities.
Later, various internal combustion engine schemes were put forward, but they were not put into practice before the middle of the 19th century.It was not until 1860 that Lenois of France designed and manufactured the first practical gas engine by imitating the structure of the steam engine.This is an internal combustion engine with no compression, electric ignition and lighting gas.Lenois first used elastic piston rings in internal combustion engines.The thermal efficiency of this gas engine is about 4%.
Barnett of England once advocated compressing the combustible mixture before ignition, and then someone wrote an article on the important role of compressing the combustible mixture, and pointed out that compression can greatly improve the efficiency of the Lenois internal combustion engine.In 1862, French scientist Rosa put forward the requirement of improving the efficiency of internal combustion engine after theoretical analysis of the thermodynamic process of internal combustion engine, which was the earliest four stroke working cycle.
In 1876, Otto, the German inventor, applied the principle of Rosa to create the first booster, single cylinder, horizontal, 3.2kW (4.4hp)Four stroke internal combustion engineThe gas is still used as fuel, and the flame ignition is adopted. The rotating speed is 156.7 rpm, the compression ratio is 2.66, the thermal efficiency reaches 14%, and the operation is stable.At that time, both power and thermal efficiency were the highest.
Otto internal combustion engine has been promoted and its performance is also improving.In 1880, the single unit power reached 11~15kW (15~20hp), and in 1893, it increased to 150kW.Due to the increase of compression ratio, the thermal efficiency also increased. In 1886, the thermal efficiency was 15.5%, and in 1897, it was as high as 20-26%.In 1881, British engineer Clark successfully developed the first two-stroke gas engine and exhibited it at the Paris Expo.
With the development of petroleum, gasoline and diesel that are easier to transport than gas have attracted people's attention. The first thing to try is gasoline that is easy to volatilize.In 1883, the GermanDaimler Daimler successfully created the first vertical gasoline engine, which is characterized by light weight and high speed.At that time, the speed of other internal combustion engines did not exceed 200 rpm, but it jumped to 800 rpm, especially meeting the requirements of transportation machinery.From 1885 to 1886, the successful operation of gasoline engine as vehicle power greatly promoted the development of automobiles.At the same time, the development of automobilepromoteThe improvement and enhancement of gasoline engine.Soon the gasoline engine was used to power the boat again.
German engineer in 1892diesel (Diesel) Inspired by the dust explosion in the flour mill, it is envisaged that the air sucked into the cylinder will be highly compressed to make its temperature higher than that of the fuelAutoignition temperatureAnd then blow the fuel into the cylinder with high-pressure air to ignite it.His first compression ignition internal combustion engine (diesel engine) was successfully developed in 1897, opening up a new way for the development of internal combustion engines.
Diesel began to try to make the internal combustion engine realize the Carnot cycle in order to obtain the highest thermal efficiency, but in fact, he achieved an approximate constant pressure combustion, with a thermal efficiency of 26%.The advent of compression ignition internal combustion engine has caused the worldMachinery industryOf great interest, the compression ignition internal combustion engine was also named after its inventor, Diesel Engine.
This kind of internal combustion engine will mostly use diesel as fuel in the future, so it is also called diesel engine.In 1898, diesel engines were first used for stationary enginesGenerator SetIt was used as merchant ship power in 1903, installed on ships in 1904, and the first diesel engine poweredInternal combustion engineIt was made and began to be used in automobiles and agricultural machinery around 1920.
As early asReciprocating piston internal combustion engineBefore its birth, people had devoted themselves to creating rotary piston internal combustion engines, but none of them was successful.Until 1954,Federal GermanyAfter the engineer Wankel solved the sealing problem, it was developed in 1957Rotary piston engine, known asWankel engine。It has a nearly triangular rotating piston, which rotates in the cylinder with a specific profile. PressOtto cycleWork.suchEngine powerHigh, small size, small vibration, smooth operation, simple structure and convenient maintenance, but due to its poor fuel economy and low speedtorqueLow, poor exhaust performance, so it is only used on individual models of cars.
Development trend
From the market transactions of China's machinery industry in late February 2013, it can be seen that there is a peak procurement season after the festival.Among them, the prosperity of the internal combustion engine and accessories market recovered, ranking second with 18% market share.[3]
According to the analysis, the manufacturing of internal combustion engines and accessories is a supporting product of automobile, motorcycle, shipbuilding, industrial machinery, agricultural machinery and other industries, and its product performance must meet the needs of downstream industries. At the same time, the operating conditions and prosperity of these industries will directly affect the market demand of internal combustion engines and accessories. The specific analysis is as follows:
1. Prospect forecast of automotive internal combustion engine
The output of internal combustion engine products is estimated according to the supporting use. During the "12th Five Year Plan" period, the annual output of vehicle internal combustion engines is expected to reach 30 million sets.
2. Prospects of Motorcycle and Marine Internal Combustion Engine
The output of internal combustion engine products is expected to reach 26 million gasoline engines for motorcycles annually during the 12th Five Year Plan period according to the supporting use.
3. Prospect forecast of internal combustion engine for construction machinery
During the "Twelfth Five Year Plan" period, the product output is expected to reach 1 million sets of internal combustion engines for construction machinery annually according to the supporting use.
System mechanism
The engine is composed of many mechanisms andsystem composition A complex machine.Either gasoline engine or diesel engine;Whether it is a four stroke engine or a two stroke engine;WhetherSingle cylinder engine, orMulti cylinder engine。In order to complete energy conversion, realize work cycle and ensure long-term continuous normal operation, the following mechanisms and systems must be available.[4]
(1) Crank connecting rod mechanism
Valve train
Crank and connecting rod mechanism is the main moving part of engine to realize work cycle and complete energy conversion.It consists of body groupPiston connecting rod setandCrankshaft flywheel setEtc.In the power stroke, the piston bears the gas pressure to make a linear movement in the cylinder, converts into the rotating movement of the crankshaft through the connecting rod, and outputs power from the crankshaft.During the intake, compression and exhaust strokes, the flywheel releases energy and converts the rotating motion of the crankshaft into the linear motion of the piston.
The function of the valve distribution mechanism is to open and close the inlet valve and exhaust valve regularly according to the working order and process of the engine, so that the combustible mixture or air can enter the cylinder and exhaust gas can be discharged from the cylinder to realize the air exchange process.The valve train mostly adopts overhead valve train, which is generally composed of valve group, valve drive group and valve drive group.
The function of the gasoline engine fuel supply system is to prepare a certain amount and concentration of mixture according to the requirements of the engine, supply it to the cylinder, and exhaust the burned exhaust gas from the cylinder to the atmosphere;The function of the diesel engine fuel supply system is to supply diesel and air into the cylinder respectively, form a mixture in the combustion chamber and burn it, and finally exhaust the burned exhaust gas.
(4) Lubrication system
The function of the lubrication system is to deliver a certain amount of clean lubricating oil to the surface of parts in relative motion to realize liquid friction, reduce friction resistance and reduce wear of parts.Clean and cool the surface of parts.The lubricating system is usually composed of lubricating oil passageoil pump, oil filter and some valves.
The function of the cooling system is to dissipate part of the heat absorbed by the heated parts in time to ensure that the engine works at the most appropriate temperature.Water-cooled engineThe cooling system ofWater pump, fan, water tank, thermostat, etc.
In gasoline engines, the combustible mixture in the cylinder iselectric sparkIt is ignited and is installed on the cylinder head of the gasoline engine for this purposespark plug, the spark plug head extends into the combustion chamber.All equipment that can generate electric spark between spark plug electrodes on time is called ignition system, which is usually composed ofBattery, generatorDistributor, ignition coil, spark plug, etc.
(7) Starting system
In order to make the engine transition from static state to working state, the crankshaft of the engine must be rotated with external force to make the piston reciprocate, and the combustible mixture in the cylinder burns and expands to work, pushing the piston downward to make the crankshaft rotate.The engine can run by itself and the working cycle can be carried out automatically.Therefore, the whole process from the moment when the crankshaft starts to rotate under the external force to the moment when the engine starts to idle automatically is calledEngine starting。The device needed to complete the starting process is called the starting system of the engine.The gasoline engine consists of the above two mechanisms and five systems, namely, the crank connecting rod mechanism,Valve train, fuel supply system, lubrication system, cooling system, ignition system and starting system;The diesel engine is composed of the above two mechanisms and four systems, namely, the crank connecting rod mechanism, the valve train, the fuel supply system, the lubrication system, the cooling system and the starting system. The diesel engine is compression ignition and does not need an ignition system.
CylinderIt is a cylindrical metal part.The sealed cylinder is the source of realizing work cycle and generating power.Each cylinder equipped with a cylinder liner is installed in the engine body, and its top end is sealed with a cylinder head.The piston can reciprocate in the cylinder liner and seal the cylinder from the lower part of the cylinder, thus forming a sealing space with regular volume changes.The fuel burns in this space and is driven by the gas power generatedPiston movement。The reciprocating motion of the piston is pushed by the connecting rodcrankshaftThe crankshaft rotates fromfree wheelThe end will power output.The crank connecting rod mechanism, which is composed of piston group, connecting rod group, crankshaft and flywheel, is the main part of internal combustion engine to transmit power.
The piston set consists of piston, piston ringpiston pinEtc.The piston is cylindrical, with piston rings on it, so as to seal the cylinder when the piston moves reciprocally.The upper piston rings are called gas rings, which are used to seal the cylinder to prevent gas leakage in the cylinder. The lower ring is called oil ring, which is used to scrape off the excess lubricating oil on the cylinder wall to prevent the lubricating oil from entering the cylinder.The piston pin is cylindrical. It penetrates the pin hole on the piston and the small end of the connecting rod to connect the piston and the connecting rod.The big end of the connecting rod is divided into two halves, which are connected by connecting rod screws and connected with the crank pin of the crankshaft.When the connecting rod works, the small end of the connecting rod reciprocates with the piston, the large end of the connecting rod rotates around the crankshaft axis with the crank pin, and the rod body between the large and small ends of the connecting rod makes a complex swing motion.
The function of the crankshaft is to convert the reciprocating motion of the piston into rotary motion, and transmit the work done by the expansion stroke through the flywheel installed on the rear end of the crankshaft.The flywheel can store energy, make other strokes of the piston work normally, and make the crankshaft rotate evenly.In order to balance the inertia force and reduce the vibration of the internal combustion engine, a balance mass is also properly installed on the crank of the crankshaft.
Common terms
Working cycle: conversion of heat energy and mechanical energy of internal combustion engine, continuous intake, compression, power and exhaust processes in the cylinder through the piston.The process of each machine is called a work cycle.[2]
Piston stroke: the minimum linear distance between top dead center and bottom dead center is called piston stroke (or piston stroke), and the minimum linear distance between the connecting center of crankshaft and connecting rod big end and the rotating center of crankshaft is called crank rotating radius.
Top dead center and bottom dead center: When the piston moves in the cylinder, the highest point is called top dead center (or top dead center), and the lowest point is called bottom dead center.
Working volume: when the piston moves from top dead center to the next point, it is called the cylinder volume (displacement of piston).
Compression ratio: is the degree to which the engine gas mixture is compressed
Crank connecting rod mechanism
The ratio of the total volume of the cylinder to the volume of the compressed cylinder (that is, the volume of the combustion chamber) indicates that the air is full of the cylinder. The larger the air compression ratio, the more heavily the gas is compressed within a certain range when the piston moves, the higher the gas temperature and pressure, and the higher the efficiency of the internal combustion engine.
Structure classification
Announce
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internal-combustion engine
1. According to the fuel used: gasoline engine, diesel engine, natural gas (CNG)LPGEngineEthanol engineOtherDual fuel engine(dual fuel engine) and Bi fuel engine.
2. According to the ignition mode in the cylinder: positive ignition and compression ignition
3. According to the number of strokes: twostrokeFour stroke
4. According to the movement mode of piston, it can be divided into reciprocating type and rotary type
5. According to the cooling mode of cylinder, it can be divided into water cooling type and air cooling type
6. According to the number of cylinders: single cylinder engine, multi cylinder engine
7. According to the speed of internal combustion engine, it can be divided into low speed (<300r/min), medium speed (300~1000r/min) and high speed (>1000r/min);
8. According to the charge pressure of air intake: naturally aspirated, supercharged
9. According to the cylinder arrangement, internal combustion engines can be divided into in-line, oblique, opposed, V-shaped and W-shaped.
There are many classification methods for internal combustion engines. According to different classification methods, internal combustion engines can be divided into different types. Let's take a look at internal combustion engines
The spark ignition engine has three major structures and five major systems.The three major structures are crank connecting rod, valve mechanism and engine body, and the five major systems are oil supply, cooling, lubrication, starting and ignition.
Compression ignition engine has three major structures and four major systems.The three mechanisms are crank connecting rod, valve mechanism and engine body, and the four systems are oil supply, cooling, lubrication and starting.
Internal combustion engines can be divided into gasoline engines and diesel engines according to the different fuels used.The internal combustion engine using gasoline as fuel is called gasoline engine;The internal combustion engine using diesel as fuel is called diesel engine.Compared with diesel engines, gasoline engines have their own characteristics;The gasoline engine has high speed, low quality, low noise, easy starting and low manufacturing cost;The diesel engine has large compression ratio, high thermal efficiency, and better economic performance and emission performance than the gasoline engine.
According to the journey
Internal combustion engines can be divided intoFour stroke internal combustion engineandTwo-stroke internal combustion engine。Turn the crankshaft for two revolutions (720 °), and the piston moves up and down in the cylinder for four strokes. The internal combustion engine that completes one working cycle is called a four stroke internal combustion engine;The internal combustion engine that rotates the crankshaft for one circle (360 °) and the piston moves up and down in the cylinder for two strokes to complete one working cycle is called a two-stroke internal combustion engine.automobile engineFour stroke internal combustion engines are widely used.
Cooling mode
Internal combustion engine according toCooling modeDifferent can be divided intoWater-cooled engineandAir-cooled engine。The water-cooled engine is used inCylinder blockAnd cylinder head cooling water jacketCoolantBeing cooled as a cooling medium;The air-cooled engine uses the air flowing between the cylinder block and the radiator on the outer surface of the cylinder head as the cooling medium for cooling.The water-cooled engine has uniform cooling, reliable operation and good cooling effect, and is widely used in modern vehicle engines.
Number of cylinders
Internal combustion engines can be divided intoSingle cylinder engineandMulti cylinder engine。An engine with only one cylinder is called a single cylinder engine;An engine with more than two cylinders is called a multi cylinder engine.For example, two cylinder, three cylinder, four cylinder, five cylinder, six cylinder, eight cylinder and twelve cylinder engines are all multi cylinder engines.Modern vehicle engines mostly use four cylinder, six cylinder and eight cylinder engines.
Cylinder arrangement
Internal combustion engines can be divided intouniserial andDiallel)。The cylinders of a single row engine are arranged in a row, usually vertically. However, in order to reduce the height, sometimes the cylinders are arranged obliquely or even horizontally;The dual row engine arranges the cylinders into two rows, and the included angle between the two rows<180 ° (generally 90 °) is calledV-engine, if the included angle between the two columns=180 °, it is called opposed engine.
Pressurization mode
internal-combustion engine
Internal combustion engine according toAir intake systemWhether supercharging is adopted can be divided into naturally aspirated (non supercharged) engines and forced aspirated (supercharged) engines.Gasoline engines are usually naturally aspirated;In order to improve the power of diesel engines, turbocharged engines are used.
Marine machine
Marine internal combustion engines can use diesel, gasoline, kerosene or gas, natural gas as fuel.Gas engines are called gas engines. Gasoline engines and gas engines have small power and are only used on small ships.
working principle
The cylinder head is provided with an air inlet and an exhaust passage, which are equipped with inlet and exhaust valves.Fresh charge (i.e. air or combustible mixture of air and fuel)Air filter, air intake pipe, air inlet and air inletvalveCharge the cylinder.The expanded fuel gas is discharged into the atmosphere through the exhaust valve, exhaust duct and exhaust pipe, and finally through the exhaust muffler.The opening and closing of the intake and exhaust valves are controlled byCamshaftThe intake and exhaust cams on the are respectively controlled by transmission parts such as tappet, push rod, rocker arm and valve spring. This set of parts is calledInternal combustion engine valve train。The intake and exhaust system is usually composed of air filter, intake pipe, exhaust pipe and exhaust muffler.[1]
In order to supply fuel into the cylinder, internal combustion engines are equipped with oil supply systems.The gasoline engine passes thecarburetorThe air is mixed with gasoline in a certain proportion (air-fuel ratio), and then supplied to the cylinder through the air inlet pipeignition systemThe controlled spark is ignited regularly.The fuel of the diesel engine is injected into the combustion chamber through the fuel injection system of the diesel engine and ignites under high temperature and pressure.
The combustion of fuel in the cylinder of an internal combustion engine heats the piston, cylinder liner, cylinder head, valves and other parts and raises the temperature.In order to ensure the normal operation of the internal combustion engine, the above parts must be operated at the permitted temperature without damage due to overheating, so a cooling system must be provided.
The internal combustion engine cannot automatically switch from the stopped state to the running state. The crankshaft must be turned by external force to start it.The device that generates external force is called starting device.Common starting methods include electric starting, compressed air starting, gasoline engine starting and manual starting.
The working cycle of the internal combustion engine is composed ofinlet, compression, combustion and expansion, exhaust and other processes.Among these processes, only the expansion process is the process of doing external work, and other processes are required to better realize the process of doing work.According to the number of strokes to achieve a working cycle, the working cycle can be divided into four stroke and two stroke.
Working principle diagram of internal combustion engine
Four stroke refers to the completion of a working cycle within four strokes of intake, compression, power (expansion) and exhaust, during which the crankshaft rotates for two revolutions.During the intake stroke, the inlet valve is opened and the exhaust valve is closed.The air flowing through the air filter, or the combustible mixture formed by mixing the carburetor with gasoline, enters the cylinder through the intake pipe and inlet valve;During the compression stroke, the gas in the cylinder is compressed, the pressure increases, and the temperature rises;The expansion stroke is to inject oil or ignite before compressing TDC, so that the mixture will burn, producing high temperature and pressure, pushing the piston down and doing work;During the exhaust stroke, the piston pushes the exhaust gas in the cylinder to exhaust through the exhaust valve.Then the next working cycle starts from the intake stroke.
Two stroke refers to the completion of a working cycle in two strokes, during which the crankshaft rotates for one revolution.First, when the piston is at the bottom dead center, the air inlet and exhaust ports are opened, and the fresh charge isAir inletFill the cylinder and sweep the exhaust gas in the cylinder to exhaust from the exhaust port;Then the piston goes up, closes both the inlet and exhaust ports, and the charge in the cylinder begins to be compressed until the piston is close to TDC and ignites or injects fuel to burn the combustible mixture in the cylinder;Then the gas in the cylinder expands, pushing the piston downward to do work;When the exhaust port is opened when the piston moves downward, the exhaust gas will be discharged. The piston will continue to move downward to the bottom dead center, completing a working cycle.
The exhaust process and intake process of internal combustion engine are collectively referred to as air exchange process.The main function of air exchange is to exhaust the exhaust gas of the previous cycle as clean as possible, so that this cycle can be supplied with as much fresh charge as possible, so that as much fuel as possible can be completely burned in the cylinder, thus generating more power.The quality of air exchange process directly affects the performance of internal combustion engine.Therefore, in addition to reducing the flow resistance of the intake and exhaust systems, the main purpose is to make the intake and exhaust valves open and close at the most appropriate time.
In fact, the intake valve is opened before TDC to ensure that the intake valve has a large opening when the piston goes down, which can reduce the flow resistance at the beginning of the intake process, reduce the work consumed by suction, and at the same time, fill more fresh charge.When the piston runs to the bottom dead center in the intake stroke, due to the air flow inertia, the fresh charge can still continue to fill the cylinder, so the intake valve will be delayed to close after the bottom dead center.
The exhaust valve is also opened in advance before the bottom dead center, that is, the exhaust starts after the expansion stroke. This is to make use of the high gas pressure in the cylinder to make the exhaust gas flow out of the cylinder automatically, so that the gas pressure in the cylinder is lower when the piston moves from the bottom dead center to the top dead center, so as to reduce the work consumed by the piston to exhaust the exhaust gas out of the cylinder.The purpose of closing the exhaust valve after TDC is to use the inertia of exhaust flow to exhaust the residual exhaust gas in the cylinder more cleanly.
Application
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Working indicators
internal-combustion engine
1. Power performance index: how much power is emitted and how much power/torque reserves are.
2. Economic performance index: within unit power and unit timeFuel consumption。
3. Reliability and durability indicators: the longest running time between overhaul or replacement of parts and long-term fault free working capacity.
4. Environmental performance indicators (NOx, HC, CO, particulateNoise）: Emission of harmful substances per unit power per unit time.
Advantages and disadvantages
Utilization range of internal combustion engine
Internal combustion engines are widely used.All kinds of transportation vehicles (cars, tractors, diesel locomotives, etc.) on the ground, mining, construction and engineering machinery, because of the power limit of the country, have created many places to use their own power supply to generate electricity. Water transportation can be used as the main engine and auxiliary engine of inland and marine ships.In military terms, such asTank, armored vehicles, infantry fighting vehicles, heavy weapon tractors and various surface ships, etc.
① The heat energy utilization rate of internal combustion engine is high.The maximum thermal efficiency of turbocharged diesel engine can reach 46%.The steam engine is only 11-16%.
② The power range is wide and the adaptability is good. The minimum internal combustion engine power is less than 0.73 kW, and the maximum internal combustion engine power can reach 34000 kW.
⑤ Compact structure, light weight, small size, less fuel and water consumption.
④ It is easy to operate and start quickly.Under normal conditions, ordinary diesel engines and gasoline engines can be started within 3-5 seconds, and can operate at full load in a short time.Simple and safe.In the petroleum industry, the oil exploration work is all in the field with high mobility. The selection and requirements for power equipment are: it has sufficient power, compact structure, light weight, easy handling and installation, and low fuel and water consumption.Therefore, internal combustion engines are widely used in oil exploration.
The disadvantages of internal combustion engines are:
(1) High fuel requirements High speed internal combustion engines generally use gasoline or light diesel oil as feedstock, and have strict requirements on fuel cleanliness.
⑵ The environmental pollution is becoming more and more serious.
⑶ Complex layout and development space - the operation route of multi source business in the electromechanical industry and the way of long-term accumulation and transformation of a large number of potential customers.
Performance Development
The performance of internal combustion engine mainly includes power performance and economic performance.The power performance refers to the power (torque) emitted by the internal combustion engine, which represents the amount of energy conversion of the internal combustion engine. The parameters that mark the power performance include torque and power.Economic performance refers to the amount of fuel consumption when a certain power is delivered, which indicates the quality of energy conversion. The parameters that mark economic performance are thermal efficiency andFuel consumption rate。
The future development of internal combustion engines will focus on improving the combustion processMechanical efficiencyReduce heat loss and fuel consumption rate;Develop and utilize non petroleum fuels and expand fuel resources;Reduce harmful components in exhaust, reduce noise and vibration, and reduce environmental pollution;Adopt highSupercharging technology, further strengthen the internal combustion engine and increase the power of single machine;developmentCompound engine、heat insulationtypeTurbo compound engineEtc;The microprocessor is used to control the internal combustion engine, so that it is in the best conditionworking conditionLower running;Strengthen the research on structural strength to improve the working reliability and life, and constantly createNew internal combustion engineThe technology of variable valve, variable lift, variable phase, or even stopping several cylinders failed to continuously change the cylinder diameter while traveling, but it is equivalent.
The engine has a barrel shaped cylinder body, and a round hole is arranged at the back of the barrel bottom and in the middle of the barrel bottom.There is also a cylinder body, which looks like a chopstick passing through a thick round cake and bonding. The chopstick is the shaft, which also passes through the hole at the bottom of the barrel cylinder body. The cake body is also included in the barrel, and is sealed into a hollow cylinder cavity.The volume of the cylinder cavity can be changed. For example, as long as the barrel is fixed, it can be achieved by pumping the shaft with a mechanical device or a hydraulic device.
The bottom of the barrel is slit from the edge of the round hole to the inner wall of the barrel, and a rectangular plate is inserted;From the round edge to the shaft cutting slot, the cake surface is also inserted with a rectangular plate. The two rectangular plates can divide the cylinder cavity into two parts to form two sealing cylinder cavities, the first sealing cylinder cavity and the second sealing cylinder cavity.One of the sealed cylinder cavities is opened from the side of the rectangular plate on the barrel wall, filled with high-pressure gas, or filled with oil and gas mixture and ignited;The second sealing chamber deflates from the opening of a rectangular plate on the barrel wall which is separated from the previous opening.When the barrel is fixed, the rectangular plate will pull the cake and chopsticks to rotate, and vice versa.
The first sealing chamber stops gas supply from the minimum and inflation to a certain phase (corner), which can be achieved by valves or by controlling the oil and gas supply.Due to the expansion of high-pressure gas, the device will continue to rotate, and the air pressure in the first sealing cylinder chamber will decrease until it is slightly lower than the ambient air pressure, which will cause rotation resistance.So the second rectangular plate needs to open a hole near the edge of the head, install a one-way valve, and supply air inward.If the initial air pressure is appropriate, when the second rectangular plate turns to the second opening, the air pressure in the first sealing cylinder chamber is just equal to or close to the ambient air pressure, which is the most economical.The third case is that there is a small amount of residual pressure.
When two rectangular plates are about to meet, they need to avoid.Then a curved chute is carved from the inner circle of the skirt of the barrel, and a sliding block is installed, which is connected with the second rectangular plate;A hollow cylinder is sheathed on the side where the shaft passes through the bottom of the barrel. The outer circle is carved with a curved chute, and a sliding block is installed to connect with the first rectangular plate.The chute is composed of a circle and a cycloid, which controls the forward punching, jacking and withdrawal of the rectangular plate.The bottom of the bucket and the cake are thick enough, so they won't come out.The second rectangular plate rotates with the cake in the rotation direction;In the axial direction, it is controlled by the chute on the barrel, so it can still resist the bottom of the barrel when changing the volume.In the same way, the first rectangular plate can always hold against the inner surface of the pie.
This device converts the internal energy of high-pressure gas into kinetic energy along an arc path on an impact surface. It is a power mechanical device.Conversely, it can also be driven by the machine to rotate in reverse direction to produce compressed air, or as a brake.Make a small capacity air compressor to produce high-pressure oil and gas, add an ignition device, and then make a capacity power mechanical device to convert the internal energy of a large amount of high-temperature and high-pressure gas after combustion into kinetic energyengine。
Its work path is an arc, and its capacity can be changed steplessly, which means that it can be changedEngine displacement。With the accelerator, the air pressure after combustion can be changed and the speed can be flexibly changed;By changing the displacement and cooperating with the transmission, it can adapt to various loads within a certain range and adopt the "most economical" method mentioned above.If multiple sets of rectangular plates are used opposite, the bending of the shaft can be reduced;It is continuous exhaust, so the noise is low;Multiple sets of cylinders can be connected with each other in a staggered manner, ensuring stable power.It can minimize the residual pressure discharge, andloadThe most economical working condition can be adopted under all conditions, so it is easy to use energy-saving technology.
As a kind of engine, it is different from steam engine, piston engine andDelta rotor engine。It is called "variable capacity arcing cylinder engine"
theoretical research
Three theories[1]
P-v diagram of constant pressure heating internal combustion engine cycle
(3) Mixed heating cycle (Diesel cycle);Corresponding to diesel engine
Theoretical cycle
It is an ideal cycle for quantitative analysis by simplifying the actual cycle.
research objective
(1) The relationship between the basic thermodynamic parameters in the working process is clarified with simple formulas to clarify the basic way to improve η it;
(2) Determine the theoretical limit of η it;To judge the perfection degree and improvement potential of internal combustion engine working process.
(3) Analyze and compare the economy and power of different thermal cycle modes.
Simplify Assumptions
(1) Air as working medium, ideal gas;
(2) Refrigerant replacement and leakage loss are not considered, and inlet and exhaust flow loss and impact are ignored;
(3) Ideal adiabatic isentropic process;The working medium does not exchange heat with the outside world;
(4) Ideal heating and exothermic process.
Ship application
Relevant curves of diesel power plant
Diesel power unitIt is the main power plant on modern ships.The main engines of modern ships and warships aremarine diesel，burn gasIs calledGas engine, gasoline engine and gas engine have low power, only used forSmall shipsOn.
Mechanical loss
Average mechanical loss pressure pmm: the work lost in one cycle per unit cylinder working volume of the engine.It can be used to measure the size of mechanical loss.That is:
1、 Composition of mechanical loss:[5]
1. Friction loss between piston and piston ring: accounting for the main part of friction loss, about 45-65%
2. Friction loss between bearing and valve mechanism: including friction loss of all main bearings, connecting rod bearings, camshaft bearings, etc.The larger the bearing diameter, the higher the speed, and the greater the loss.15-30%。
3. Power consumption of driving auxiliary mechanism: it refers to the component assembly necessary to ensure engine operation, such as cooling water pump assembly（Air-cooled engineCooling fan), oil pump, fuel injection pump, governor, etc;10-20%.
4. Fluid friction loss: Some work will be consumed to overcome oil mist, air resistance and crankcase ventilation.
5. Loss of driving scavenging pump and supercharger: two-stroke orSupercharged engineIn addition, the loss caused by the compression of the intake air shall be added.10-20%
Distribution
Name of mechanical loss
% of Pm
% of Pi
Friction loss, including movable connecting rod, piston ring bearing and crankshaft valve mechanism
60～7545～6515 ～ 202～3
8 ～ 20
Loss of driving various accessories, including water pump, fan, oil pump, electrical equipment
10～20 2～8 6～3 1～2 1～2
1 ～5
Loss of driven supercharger
6 ～ 10
Pump air loss
10~20
2~4
Total power loss
10~30
Loss measurement
1. Indicator diagram method: use the indicator diagram to calculate the Pi value, measure the effective power of the engine Pe from the dynamometer, and then calculate the production Pm, hm and Pmm values.
Problem: The error comes from the correct determination of the top dead center position of the piston on the P-V diagram and the measurement error.In addition, the unevenness of each cylinder will also cause certain errors.The indicator diagram method can obtain satisfactory results only when the top dead center position can be accurately corrected.Limitation: Only the overall mechanical loss can be measured.
2. Backdrag method: When the engine runs stably under a given working condition and the temperature of cooling water and oil reaches the normal value, cut off the oil supply to the engine, convert the electric dynamometer into a motor, pull the engine backward at a given speed, and maintain the temperature of cooling water and oil unchanged. The measured backdrag power is the mechanical loss power of the engine under this working condition.
Difference from actual operation: (1) The gas pressure drops significantly in the expansion stroke, making the piston and connecting rod.The friction loss of crankshaft is reduced;(2) Due to the low temperature and high density in the exhaust process, Pp is larger than the actual value;(3) During the expansion and compression stroke of the backward drag, there is heat transfer loss from the charge to the cylinder wall. When measuring the effective power under this condition, this part of heat transfer loss has been taken into account.
The comprehensive result is that the power consumed during reverse towing is more than the actual mechanical loss of the diesel engine. In the low compression ratio engine, the error is about 5%, and in the high compression ratio engine, the error can be as high as (15-20)%. Therefore, this method is applicable to the gasoline engine with low compression ratio.
internal-combustion engine
3. Cylinder out method: after the internal combustion engine is adjusted to the given working condition and works stably, first measure its effective power Pe, and then stop the operation of a cylinder with the injection pump rack position or throttle unchanged, and quickly restore the speed to the original value by reducing the braking torque, and re measure its effective power Pe '.If the working condition of other cylinders and the mechanical loss of the engine do not change after the cylinder is extinguished, the original indicated power of the extinguished cylinder is (Pi) x.Put out the fire for each cylinder in turn, and finally obtain the indicated power of the whole engine from the sum of the indicated power of each cylinder.
Limitation: It can only be used for diesel multi cylinder engine.
4. Fuel consumption line method: ensure that the engine speed remains unchanged, gradually change the fuel supply, measure the relationship between the hourly fuel consumption B and the load pme, draw a load characteristic curve, extend the intersection of the straight line segment with the abscissa, and the distance from this intersection point to the origin is the average mechanical loss pressure pmm.
It is only applicable to pmm and η it, which do not change with the load, and it is only applicable to diesel engines.
In short;The back drag method can only be used when an electric dynamometer is equipped, and is not applicable to high-power engines. It is more suitable for measuring the mechanical loss of gasoline engines with low compression ratios.For exhaustTurboFor diesel engines, the normal operation of the supercharging system is damaged by the reverse drag method and the cylinder out method, so the mechanical loss can only be measured by the indicator diagram method and the fuel consumption line method.For turbocharged and highly turbocharged diesel engines in the exhaust turbine (pb>0.15 MPa), there is no other applicable method to replace it except the indicator diagram.
Attention
Announce
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Misuse
Theoretical cycle
1. Recycle the lubricating oil or mix the oil of different quality for use[1]
3. One wayFlow control valveOr remove the ventilation hose randomly after it is damaged
4. Large capacity battery has long service life
5. Add electrolyte at will
6. Increase the terminal voltage of generator at random
7. The air filter is short circuited for a long time or the filter of different specifications is replaced randomly
8. Always shut down under high power and high temperature
9. The lubricating oil in the high-pressure oil pump is not properly filled or replaced
10. The injector injection pressure is adjusted too high
11. Remove the air steam valve on the radiator at will
12. Replace the spark plug at will
Fuel use
Fuel is the power source of the engine, which also causesengineThe main factor of the fault is that clean fuel does not contain water and impurities, otherwise the fuel injection pump and nozzle will be severely worn or even damaged.[4]
In China, the fuel quality problem has always been the main reason for the reduction of engine life and failure. Therefore, when using imported engines, try to use high-quality low sulfur fuel. If the requirements cannot be met, the fuel delivery pipeline can be modifiedOil water separatorA primary filter or oil-water separator is added in front, and the filter element level is selected based on the engine output power.
When using inferior fuel, the fuel tank must be cleaned regularly, otherwise it is easy to accumulate on the tank wall and bottom due to the water and impurities contained in the inferior fuel in the fuel tank. If it is not cleaned for a long time, the accumulated mud peel will fall off, and it will enter the fuel pipeline during work, resulting in blockage of the pipeline or fuel filter element. Good maintenance habits should be observed during daily maintenance,Drain the water impurities deposited in the oil tank and the accumulated water in the oil-water separator.
contaminated
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air pollution
Internal combustion engines (such as reciprocating internal combustion engines) will emit emissions due to incomplete combustion of carbon containing fuels during operationatmospheric pollutant。The most important emissions of internal combustion engines arecarbon dioxide, water vapor and some carbon black particles.Depending on the operating conditions and the oil gas ratio, the internal combustion engine also emits emissionscarbon monoxide、nitrogen oxide 、sulfide(Mainlysulfur dioxide）And some unburnedhydrocarbon。
noise pollution
The internal combustion engine will produce significant noise pollution when working.For example, cars on the road will produce noise, and aircraft will also produce jet noise when flying (especiallySupersonic aircraft）。rocket engineThe noise generated is the largest.
