Why is the economy of plunger carburetor engine greatly reduced when the throttle valve is closed quickly (fast oil collection)

1, top dead center: When the piston moves linearly back and forth in the cylinder, the piston moves up (down) to the highest (low) position, that is, the extreme position where the top of the piston is farthest (near) from the rotation center of the crankshaft, which is called top (bottom) dead center. 2. Piston stroke: the distance from one dead point to another, that is, the distance between the upper and lower dead points, is called piston stroke. Crankshaft rotation 180 degrees. 3. Crank radius: The distance from the center of crankshaft rotation to the center of crank pin is called crankshaft radius, which is generally expressed by R. Usually, the piston stroke is twice the radius of crankshaft, that is, S=2R. 4. Cylinder working volume: the volume swept by the piston when it moves from one dead point to another, which is called cylinder working volume (L) and generally expressed by Vh. 5. Combustion chamber volume. The volume of space above the piston is called the combustion chamber volume. 6. Total cylinder volume: When the piston is at the bottom dead center, the space volume above the piston is called the total cylinder volume. 7. Engine displacement: The total working volume of each cylinder of a multi-cylinder engine is called engine displacement. 8. Compression ratio: Compression ratio is a very important concept of an engine, which indicates the degree of gas compression and is the ratio of the volume before gas compression to the volume after gas compression. That is, the ratio of the total cylinder volume to the combustion chamber volume. 9. Work cycle: Each work cycle includes intake, compression, work and exhaust, that is, the four processes of engine intake, compression, work and exhaust are called a work cycle. 10. Four-stroke engine: the crankshaft must rotate twice, and the piston moves up and down four times to complete a working cycle. It is called a four-stroke engine. 1 1. Two-stroke engine: an engine in which the crankshaft rotates only once and the piston reciprocates up and down twice to complete a working cycle. It is called a two-stroke engine. Engine Engine is an energy conversion mechanism, which converts heat energy generated by fuel combustion into mechanical energy.

2. Fill in the blanks (note: the underlined ones should be filled in)

1. Compared with the external combustion engine, the internal combustion engine has the advantages of high thermal efficiency, small volume, convenient movement and good starting performance. Internal combustion engines are divided into piston internal combustion engines and gas turbines. Automobile engines mainly use piston internal combustion engines.

2. The classification method of the engine is as follows: 1) According to the piston movement mode, it can be divided into two types: reciprocating piston internal combustion engine and rotary piston internal combustion engine. The former has been widely used in automobiles. 2) According to the fuel used, it is divided into gasoline engine, diesel engine and gas fuel engine. 3) According to the number of strokes required to complete a working cycle, there are two-stroke engines and four-stroke engines. The latter is widely used in automobiles. 4) According to the cooling mode, it can be divided into water-cooled engine and air-cooled engine. Water-cooled engines are widely used in automobiles. 5) According to the number of cylinders, it can be divided into single-cylinder engine and multi-cylinder engine. Almost all cars use multi-cylinder engines. 6) According to the arrangement of cylinders, it can be divided into single-row engines and double-row engines. 7) According to whether the air intake system is supercharged, it can be divided into naturally aspirated (non-supercharged) engines and forced intake (supercharged) engines.

8) The main parts of crank-connecting rod mechanism can be divided into three groups, namely, body group, piston-connecting rod group and crankshaft flywheel group.

9) The combustion chamber of the gasoline engine has a wedge-shaped combustion chamber; There are three types: basin combustion chamber and hemispherical combustion chamber.

10) Piston connecting rod group consists of piston, piston ring, piston pin, connecting rod and connecting rod bearing bush.

1 1) The piston can be divided into three parts: the piston top, the piston head and the piston skirt.

12) Piston rings are elastic split rings, including gas rings and oil rings. The gas ring plays the role of sealing and heat conduction; The oil ring plays the role of distributing oil and scraping oil. The opening of the gas ring is provided with a right-angle cut; Step incision; Oblique cuts and grooves with anti-rotation pins.

13) Connecting rod is divided into three parts: connecting rod small head, connecting rod shaft and connecting rod big head (including connecting rod cover).

14) Crankshaft consists of three parts: front end (free end), crank and rear end (power output end).

15) The valve group includes: valve, valve seat, valve guide, valve spring, valve spring retainer ring and locking plate.

16) The valve train consists of camshaft, tappet, push rod and rocker arm.

17) the fuel supply system of carburetor gasoline engine consists of carburetor, gasoline tank, gasoline filter, gasoline pump and other devices.

18) The performance indexes of gasoline mainly include evaporation, calorific value and antiknock.

19) The structure of simple carburetor consists of float chamber, throat, metering hole, nozzle and throttle valve.

20) The fuel supply system of diesel engine consists of fuel supply device, air supply device, mixed gas forming device, exhaust gas emission device, etc.

2 1) The hole injector of direct injection combustion chamber consists of injector body, pressure regulating screw, pressure regulating spring, oil return pipe bolt, oil inlet pipe joint, ejector rod, needle valve and needle valve body. Needle valve and needle valve body are collectively referred to as needle valve fittings.

22) The main parts of the cylinder of plunger fuel injection pump are plunger coupling, plunger spring, spring seat, outlet valve coupling, outlet valve spring, reducer and outlet valve pressure seat.

23) The exhaust system consists of exhaust manifold, exhaust manifold and muffler.

24) Distributed fuel injection pump consists of five parts: driving mechanism, two-stage vane pump, high-pressure pump head, automatic fuel supply advance angle adjusting mechanism and governor.

25) The types of oil pumps are piston, diaphragm, gear and vane.

25) Piston oil pump consists of pump body, mechanical oil pump assembly, manual oil pump assembly, check valve and oil circuit.

26) At present, the water cooling system used in automobile engines is mostly forced circulation water cooling system, which consists of radiator, fan, water pump, cooling water jacket and temperature regulating device.

27) Lubrication system generally consists of oil pump, oil pan, oil filter, oil radiator, various valves, sensors, oil pressure gauge and thermometer.

Third, question and answer.

1, which institutions and systems are the engines composed of?

(1, crank-connecting rod mechanism 2, valve train 3, fuel supply system 4, engine block 5, lubrication system 6 and cooling system; 7. Ignition system 8. Start the system)

2. Briefly describe the working principle of four-stroke gasoline engine.

Gasoline engine is a mixture of gasoline and air, which enters the cylinder and is ignited by electric spark. Run circularly according to the following working process. 1) intake stroke 2) compression stroke 3) power stroke 4) exhaust stroke.

3. Briefly describe the working principle of four-stroke diesel engine.

The working process of four-stroke diesel engine and four-stroke gasoline engine is the same, and each working cycle also includes four strokes: intake, compression, work and exhaust. However, the fuel used by diesel engine is diesel, which is very different from gasoline. Diesel has high viscosity, is not easy to evaporate and has low spontaneous combustion temperature, so the formation of combustible mixture, ignition mode, combustion process and changes of gas temperature and pressure are different from those of gasoline engine.

4. Compare the advantages and disadvantages of four-stroke gasoline engine and four-stroke diesel engine.

Compared with gasoline engine, diesel engine has higher compression ratio, higher thermal efficiency, lower fuel consumption rate and lower diesel price, so it has better fuel economy, less exhaust pollution and better emission performance. Their main disadvantages are low speed, large mass, high noise, large vibration and high manufacturing and maintenance costs.

5. What are the main performance indexes of the engine?

1, dynamic performance index 1) Effective torque: refers to the torque output by the engine through the crankshaft or flywheel. 2) Effective power: refers to the power output by the engine through the crankshaft or flywheel. 3) Crankshaft speed: refers to the revolutions per minute of the engine crankshaft, usually expressed by n, and the unit is r/min. 2. Economic performance indicators The fuel consumption rate is usually used to evaluate the economic performance of internal combustion engines. 3. Environmental performance emission performance indicators include smoke and dust emission, harmful gas (carbon monoxide, hydrocarbons, nitrogen oxides) emission, noise, etc.

7. Briefly describe the function and working conditions of crank-connecting rod mechanism.

1, function: Crank-connecting rod mechanism is the mechanism that the engine generates and transmits power, and through it, the heat energy released by fuel combustion is converted into mechanical energy. 2. Working conditions: The working conditions of crank-connecting rod mechanism are quite harsh, and it has to withstand high temperature, high pressure, high speed and chemical corrosion.

8. What are the structural forms of the cylinder block?

The structural forms of cylinder block are usually divided into three forms: 1, universal cylinder block 2, gantry cylinder block 3, and tunnel cylinder block cooling form: one is water cooling and the other is air cooling. The arrangement of cylinders can be divided into three types: in-line, V-shaped and opposed. Cylinder liner: There are two kinds of cylinder liners: dry cylinder liner and wet cylinder liner.

10, what is the function of cylinder gasket?

The cylinder gasket is installed between the cylinder head and the cylinder block, and its function is to ensure the sealing of the contact surface between the cylinder head and the cylinder block and prevent air leakage, water leakage and oil leakage.

1 1, briefly describe the function of the piston; Requirements of working conditions and manufacturing materials.

1. Function: bear the gas pressure and transmit it to the connecting rod through the piston pin to drive the crankshaft to rotate. The top of the piston is still part of the combustion chamber. 2. Working conditions: working at high temperature, high pressure, high speed and poor lubrication. 3. Requirements: (1) have sufficient rigidity and strength; (2) Good thermal conductivity, high pressure resistance, high temperature resistance and wear resistance; (3) The weight is small and light, and the reciprocating inertia force is reduced as much as possible. 4. Material: High-strength aluminum alloy is widely used.

12. Briefly describe the position and function of each part of the piston.

1, piston crown: the piston crown bears gas pressure and is an integral part of the combustion chamber. 2. Piston head: the part above the piston ring groove. There are three main functions of the piston head: ① to bear the gas pressure and transmit it to the connecting rod; (2) sealing the cylinder and the piston ring together; ③ The heat absorbed by the piston top is transferred to the cylinder wall through the piston ring. 3. Piston skirt: The piston skirt refers to the part from the lower end face of the oil ring groove to the bottom face of the piston. Function: Guide the piston to reciprocate in the cylinder and bear the lateral pressure. And compensate the deformation of the piston when working.

13, what is the function of the piston pin? What are the working conditions? How is it connected to the piston?

1. Function: connect the piston and the connecting rod small head, and transmit the gas pressure borne by the piston to the connecting rod. 2. Working conditions: high temperature, large periodic impact load and poor lubrication conditions. 3. Installation form: There are two ways: full floating installation and semi-floating installation.

14. What is the function of the connecting rod? Its working conditions; What materials and requirements are there for them?

1. Function: connect the piston with the crankshaft, and transmit the gas pressure borne by the piston to the crankshaft, so that the reciprocating motion of the piston can be converted into the rotary motion of the crankshaft. 2. Working conditions: bear alternating loads such as compression, tension and bending. 3. Requirements: high strength, high rigidity and light weight. 4. Material: Generally, medium carbon steel or alloy steel is forged by die forging or roll forging, and then machined and heat treated.

16, briefly describe the function of crankshaft; Working conditions; Requirements for it; Material and processing requirements.

Crankshaft is one of the most important parts of engine.

1. Function: Convert the force from the connecting rod into rotating power (torque) and output it to the outside. 2. Working conditions: Under the action of periodically changing gas pressure, reciprocating inertia force, centrifugal force and bending and torsion load generated by it. 3. Requirements: sufficient rigidity and strength, good wear resistance and lubricity, and good balance performance. 4. Materials and processing: generally made of medium carbon steel or medium carbon alloy steel by die forging. The surface of the journal is subjected to high-frequency quenching or nitriding and fine grinding. ]

17, the function and classification of crankshaft journal?

The main journal is the supporting part of the crankshaft and is supported in the main bearing seat of the crankcase through the main bearing. According to the number of main journals, the crankshaft can be divided into fully supported crankshaft and partially supported crankshaft. Fully supported crankshaft: the number of crankshaft journals is one more than the number of cylinders. Incomplete crankshaft: the number of crankshaft main journals is less than or equal to the number of cylinders.

19. Try to list the ignition sequence of four-cylinder four-stroke engine and inline six-cylinder four-stroke engine.

1) ignition sequence and crank arrangement of four-cylinder four-stroke engine: the ignition interval angle of four-cylinder four-stroke engine is 720/4 = 180. There are only two possible ignition sequences, namely 1-3-4-2 or 1-2-4-3.

2) Ignition sequence and crankshaft arrangement of four-stroke inline six-cylinder engine.

The ignition interval angle of four-stroke inline six-cylinder engine is 720/6 = 120. One emission sequence is 1-5-3-6-2-4, and the other is 1-4-2-6-3-5.

20. What is the function of crankshaft torsional vibration damper?

Function: Absorb the energy of torsional vibration of crankshaft, reduce torsional vibration and avoid strong vibration and its serious consequences. 2 1, what does the flywheel do?

Function: it is used to store the energy of power stroke, overcome the resistance of intake, compression and exhaust stroke and other resistance, and make the crankshaft rotate at a uniform speed; As a driving part of friction clutch in transmission system.

22. What is the function of the valve train? What are the layout forms?

Function: according to the working sequence and requirements of the cylinder, open and close the intake and exhaust valves on time, supply combustible mixture (gasoline engine) or fresh air (diesel engine) to the cylinder, and discharge exhaust gas in time. Arrangement: According to the arrangement of valves, there are overhead valves and side valves. The side valve type has tended to be eliminated; According to camshaft installation position: upper camshaft type, middle camshaft type and lower camshaft type; According to the transmission mode of crankshaft and camshaft, it can be divided into gear transmission, chain transmission and toothed belt transmission; According to the number of valves in each cylinder, there are 2-valve, 3-valve, 4-valve and 5-valve types. ]

23. What is valve timing? Draw the valve timing diagram and indicate the valve overlap angle.

Valve timing is the opening time and opening duration of intake valve and exhaust valve expressed by crank angle. It is usually represented by an annular diagram-valve timing diagram.

24. What is the function of valve clearance? What's the harm if the valve clearance is too large or too small?

Function: Leave room for the thermal expansion of the valve to ensure the sealing of the valve. Excessive clearance: After the intake valve and exhaust valve are opened late, the intake and exhaust time is shortened, and the valve opening height is reduced, which changes the normal valve timing and makes the engine power drop due to insufficient intake and unclean exhaust. In addition, the impact of valve train parts increases and the wear accelerates. Too small clearance: after the engine works, the parts are heated and expanded, pushing open the valve, which makes the valve not close tightly, causing air leakage, reducing power, causing serious carbon deposition or burns on the sealing surface of the valve, and even the valve hits the piston. The valve mechanism with hydraulic tappet does not need to leave valve clearance.

25. What is the function of the valve group? What are its working conditions and requirements?

Function: Control the opening and closing of intake and exhaust pipes. Working conditions: withstand high temperature, high pressure, impact and lubrication difficulties. Requirements: Sufficient strength, rigidity, wear resistance, high temperature resistance, corrosion resistance and impact resistance.

26. What is a combustible mixture? What's the role?

Combustible mixture is a mixture of fuel and air in a certain proportion. Its function: according to the requirements of various working conditions of the engine, prepare a certain amount and concentration of combustible mixture for combustion in the cylinder.

27. What are the characteristics of a simple carburetor?

When the rotational speed is constant, the law that the concentration of combustible mixture supplied by the simple carburetor changes with the throttle opening (or throat vacuum Ph) is called the characteristic of the simple carburetor.

28. What is the composition of combustible mixture and its relationship with the performance of gasoline engine?

The content of fuel in combustible mixture is called the composition of combustible mixture.

There are two ways to express the composition of combustible mixture: air-fuel ratio: the mass ratio of air to fuel contained in combustible mixture. Excess air coefficient: the concentration of combustible mixture has a great influence on the performance of the engine, which directly affects the power and economy. ]

29. What are the working characteristics of automotive gasoline engines?

1, the working condition changes widely, the load can change from 0 to 100%, the speed can rise from the lowest to the highest, and the working condition changes very quickly; 2. Most of the time when the car is running, the engine works under the medium load. Automobile engines are often 40% ~ 60%, while trucks are 70% ~ 80%.

30. What are the requirements for the composition of combustible mixture in various working conditions of automotive gasoline engine?

1, stable working condition (1), idle working condition requires rich mixture of α = 0.6 ~ 0.8. (2) The light load condition requires rich mixture α = 0.7 ~ 0.9. (3) The medium load condition requires economy, and the mixture composition α = 0.9 ~ 1. 1. (4) Maximum power Pemax is required under heavy load and full load conditions, α = 0.85 ~ 0.95.

2. Transition conditions (5) Starting conditions require the supply of extremely rich mixed gas α = 0.2 ~ 0.6. (6) Under the acceleration condition, when the throttle valve of the carburetor suddenly opens, more fuel should be forcibly supplied, and the fuel supply should be additionally increased, so that the mixture can be enriched to a sufficient degree in time.

3 1. What auxiliary devices are there in the fuel system of carburetor gasoline engine? What are their respective roles?

1. The oil tank is used to store gasoline. 2. The gasoline filter is used to remove impurities and moisture in gasoline. 3. The gasoline pump sucks the gasoline from the fuel tank, passes through the pipeline and the gasoline filter, and then pumps it into the carburetor float chamber (carburetor engine) or the oil delivery main pipe (EFI engine). Type: Mechanical diaphragm gasoline pump and electric gasoline pump are commonly used in automobiles.

32. What are the advantages of electronically controlled fuel injection system of gasoline engine?

1) accurate measurement, uniform injection, random correction, so that the air-fuel ratio is always maintained in the best area of 14.7. 2) "three noes" bring "three good". 3) Get the "three big harvests" of power, economy and purification. Engine power increase15% ~ 20%; Fuel consumption rate decreased1%~ 5%; The emission pollution value is obviously reduced, with CO < 1% and HC < 100× 10-6. 4) The cold start performance, hot start performance, transition performance, rapid deceleration and pollution prevention performance, load self-adjustment performance and flameout prevention performance are improved. 5) The control function is expanded and the self-diagnosis function is added. 6) Reduce the failure rate of gasoline engine oil circuit and circuit.

33. What are the types of fuel injection systems of gasoline engines?

1. According to the control mode, it can be divided into mechanical control, electromechanical hybrid control and electronic control. In recent ten years, electronically controlled gasoline injection system has been rapidly developed and widely used. 2. According to the different injection parts, it can be divided into in-cylinder injection and out-of-cylinder injection. Out-of-cylinder injection is divided into single point injection and multi-point injection. At present, the most widely used is multi-point injection. 3. According to whether the injection is continuous or not, it is classified as continuous injection and intermittent injection. Intermittent injection is the main injection form adopted by EFI engine at present.

Intermittent injection can be divided into three forms: simultaneous injection, group injection and sequential injection. Modern EFI engines mainly adopt sequential injection. 4. According to the measurement method of intake air, there are two ways: indirect measurement and direct measurement. 1) Indirect measurement mode ① Throttle-speed mode ② Speed-density mode ② Direct measurement mode ① Volume flow mode ② Mass flow mode.

34, what is the role of diesel fuel supply system?

Complete the storage, filtration and transportation of fuel oil, and inject it into the combustion chamber regularly, quantitatively and with certain injection quality according to the requirements of various working conditions of diesel engine, so that it can be quickly mixed with air for combustion, and finally discharge the exhaust gas into the atmosphere.

35. What are the formation characteristics of diesel engine combustible mixture?

(1) Fuel and air are mixed in the cylinder. (2) The mixing and burning time is very short. (3) Diesel oil has high viscosity and is not volatile, so it must be sprayed in mist. (4) spraying, mixing and burning.

36. What are the types of diesel combustion chambers? Please list several typical combustion chambers.

There are two types: unified combustion chamber and separated combustion chamber. 1, unified combustion chamber

A single cavity surrounded by the top of concave piston and the bottom of cylinder head is also called direct injection combustion chamber. (1)ω combustion chamber (2) Spherical combustion chamber 2. Separate combustion chamber: the separate combustion chamber consists of two parts, one is located between the piston top and the cylinder bottom, which is called the main combustion chamber, and the other is located in the cylinder head, which is called the auxiliary combustion chamber. These two parts are connected by one or several channels. (1) swirl chamber combustion chamber (2) precombustion chamber combustion chamber

37. What is the function of the syringe? What are the requirements? What are the widely used syringes at present?

The function is to inject the high-pressure diesel oil supplied by the fuel injection pump into the combustion chamber at a certain pressure. The requirements are: ① uniform atomization; (2) there is a certain injection pressure and injection range, as well as a suitable injection cone angle; (3) oil cut off quickly, no leakage. At present, there are two kinds of closed injectors, namely, split-hole injector and needle injector.

38. What is the structure of needle injector matched with split combustion chamber? What are the characteristics?

Structure: The overall structure is basically the same as the hole type, except that a shaft pin extends downward below the sealing cone surface at the lower end of the needle valve, which is in the shape of an inverted cone cylinder, and the shaft pin extends out of the spray hole, so that the spray hole becomes an annular slit. Generally, there is only one nozzle with a diameter of 1 ~ 3 mm and a low injection pressure of 12 ~ 14 MPa. Features: (1) The nozzle is large in diameter, easy to process and difficult to block. (2) It can't meet the needs of combustion chambers with special requirements on fuel injection quality.

39. What is the function of the fuel injection pump? What are the commonly used types at present?

Function: increase the pressure of diesel oil, and deliver high-pressure diesel oil to the injector regularly and quantitatively according to the working sequence and load of the engine. At present, plunger fuel injection pump and distribution fuel injection pump are mainly used.

40, plunger fuel injection pump consists of several parts? What is its workflow? What are the characteristics?

It is mainly composed of four parts: sub-pump, oil quantity adjusting mechanism, driving mechanism and pump body. Its working process includes: oil feeding process, oil supply process and oil return process ① The total stroke h of reciprocating motion of plunger is constant and is determined by the lift of cam. (2) The oil supply for each cycle of the plunger depends on the oil supply stroke hg, which is variable without camshaft control. ③ The start time of oil supply does not change with the change of oil supply stroke. ④ Turning the plunger can change the end time of oil supply, thus changing the oil supply.

4 1. What is the function of the oil quantity adjusting mechanism of plunger fuel injection pump? How to change the oil supply? How to change the timing of oil supply?

The function of oil quantity adjusting mechanism is to change the oil supply of fuel injection pump according to the change of diesel engine load and speed. The way to change the oil supply is to turn the plunger and change the oil supply stroke. Multi-cylinder machine should also pay attention to the adjustment of oil supply uniformity of each cylinder. A-type pump adopts toothed rod type oil quantity adjusting mechanism, and there is also an oil quantity adjusting mechanism, which is a pull rod fork type. The fuel supply of the fuel injection pump determines the fuel injection time of the fuel injector, and the adjustment of the fuel injection advance angle is realized by adjusting the fuel supply advance angle of the fuel injection pump.

42, the intake system of diesel engine consists of what parts? What are their respective roles? What is its classification?

The intake system of diesel engine consists of air filter and intake manifold. Among them: air filter 1, function: remove dust and sand particles contained in the air to reduce the wear of cylinders, pistons and piston rings. 2. Classification: inertia type, filtration type and comprehensive type (oil bath filter). The function of intake manifold is to distribute air or combustible mixture to the air intake of each cylinder. Intake preheating device: preheat the intake pipe with waste gas or coolant.

43. Briefly describe the function and principle of muffler.

Function: reduce exhaust noise and eliminate flames and sparks in exhaust gas. Principle: The muffler gradually reduces the exhaust pressure, attenuates the exhaust pressure pulsation, and exhausts the exhaust energy.

44. What are the types of engine exhaust purification devices? What purification measures have been adopted?

The methods of engine exhaust purification can be divided into two categories: ① internal purification; ② Off-machine purification. Among them: (1) in-machine purification measures: 1, improving the quality of combustible mixture 1) intake automatic temperature regulating device 2) exhaust gas recirculation system 2) improving combustion conditions 3) using low-pollution fuel (2) off-machine purification measures.

Uses: 1, secondary air injection system 2, catalytic converter 3, crankcase forced ventilation system, etc. The purification of diesel engine exhaust adopts: 1) exhaust gas recirculation system 2) improved combustion system unified combustion chamber→ separated combustion chamber 3) improved fuel injection timing, fuel injection rate, aperture and quantity, pilot injection and airflow 4) changed fuel properties natural gas, additives and emulsified oil 5) water injection into intake pipe, water vapor addition into intake pipe 6) pressurization technology 7) high pressure rail system 8).

45, what are the characteristics of diesel engine distribution pump?

1) has simple structure, small volume and light weight. 2) It is convenient to use and maintain, and there is no need to adjust the oil supply consistency and oil supply advance angle of each cylinder. 3) The cam lift of distribution pump is small, which is beneficial to improve the speed of diesel engine.

46, what is the function of the governor? What kinds of governors are there?

Function: automatically adjust the oil supply according to the change of engine load to ensure the stable change of engine speed in a small range. Type: Divided into two-pole (two-speed) governor, full-program (full-speed) governor, constant-speed governor and comprehensive governor by function; According to the speed sensing, there are pneumatic governor, mechanical centrifugal governor and compound governor. At present, the most widely used is the mechanical centrifugal governor.

1) Two-pole type can only automatically stabilize and limit the minimum and maximum speed of diesel engine, but it is controlled by the driver in all intermediate speed ranges. In the model, R stands for mechanical centrifugal type and Q stands for variable lever ratio. 2) The full-program governor can not only limit overspeed and stabilize idle speed, but also make the engine work stably at any selected speed within its working speed range.

47. What is the best injection advance angle of diesel engine? What's the impact? How to adjust?

Optimal fuel injection advance angle: the fuel injection advance angle that can make the diesel engine obtain the maximum power and the minimum fuel consumption rate under the condition of constant fuel supply. The fuel injection advance angle has a great influence on the diesel engine, and if it is too large, the engine will run unsteadily. Too small, the maximum pressure and thermal efficiency decrease, and the exhaust pipe emits white smoke. The optimal injection advance angle is not constant. The greater the fuel supply, the higher the rotational speed and the greater the optimal injection advance angle. The optimal injection advance angle is also related to the engine structure. 1) The fuel injection advance angle of the automatic fuel injection advance angle regulator is guaranteed by the fuel injection advance angle of the fuel injection pump. In order to make the best injection advance angle increase with the increase of speed, in recent years, mechanical centrifugal automatic fuel injection advance angle regulator is widely used in automobile diesel engines at home and abroad, which can automatically change the injection advance angle according to the change of speed. 2. Fuel injection pump coupling. The coupling connecting the camshaft of the fuel injection pump and the gear shaft driving the camshaft also plays a role in adjusting the fuel injection advance angle.

49. What is the function of the cooling system? What types are there?

Function: Make the working engine get moderate cooling, so as to keep working in the most suitable temperature range. Classification: water cooling system and air cooling system

50. Please describe the route of large circulation and small circulation of cooling water channel.

Large cycle: water pump → water distribution pipe → cylinder block water jacket → cylinder head water jacket → thermostat → radiator → water pump.

Small circulation: water pump → water distribution pipe → cylinder block water jacket → cylinder head water jacket → thermostat → water pump.

5 1. Explain the main components of water cooling system and their main uses.

(1) The function of the radiator: transfer the heat absorbed by the cooling water in the water jacket to the atmosphere, increase the heat dissipation area and accelerate the water cooling. Structure: radiator, also known as water tank, consists of upper water storage chamber, radiator core and lower water storage chamber. (2) Auxiliary water storage tank: seal the cooling system, isolate the water and gas in the cooling system, and keep the pressure stable. (3) Water pump: Pressurize the cooling water to make it circulate in the cooling system to enhance the cooling effect. (4) Fan function: improve the air flow rate through the radiator core and accelerate the cooling of water.

52. What is the function of the lubrication system? Function of lubrication system

Lubrication function: lubricate the surface of moving parts, reduce friction and wear, and reduce engine power consumption; Cleaning function: the oil circulates continuously in the lubrication system to clean the friction surface and take away the wear debris and other foreign objects; Cooling effect: the oil circulating in the lubrication system can also take away the heat generated by friction and play a cooling role; Sealing function: oil film is formed between moving parts to improve its sealing performance, which is beneficial to prevent air leakage or oil leakage; Anti-rust function: form an oil film on the surface of parts to protect the surface of parts and prevent corrosion and rust; Hydraulic function: lubricating oil can also be used as hydraulic oil, such as hydraulic tappet, which plays a hydraulic role; Shock absorption and buffering: oil film is formed on the surface of moving parts, which plays the role of shock absorption and buffering.

53. What lubrication method is used for general engines?

Because the working conditions of engine moving parts are different, the requirements for lubrication intensity are also different, so different lubrication methods should be adopted. (1) pressure lubrication: oil pump is used to continuously deliver lubricating oil with a certain pressure to the friction surface. (2) Splash lubrication: When the engine is working, the lubrication method of lubricating the friction surface by using oil droplets or oil mist splashed by moving parts is called splash lubrication. (3) Oil lubrication: In the engine auxiliary system, some components need to be lubricated by adding grease regularly. (4) Self-lubrication: In recent years, bearings containing wear-resistant materials have been used in some engines to replace bearings filled with grease. This kind of bearing does not need to be filled with grease in use, so it is called self-lubricating bearing.

54, what is the engine lubrication system? What's the role?

The system that delivers lubricating oil to the surface of moving parts to realize lubrication is called the lubrication system of the engine. The function of lubrication is to cover the friction surface with a layer of lubricating oil to form an oil film between the surfaces of moving parts, thus reducing friction resistance, power loss, parts wear and prolonging service life.

55. What is the function of the oil pump? What types are there? What are their structures?

Function: Improve the oil pressure and ensure the continuous circulation of oil in the lubrication system. At present, gear oil pump and rotor oil pump are widely used in engine lubrication system. 1, gear oil pump (1) The external gear oil pump consists of a driving shaft, a driving gear, a driven shaft, a driven gear and a shell. (2) Internal gear oil pump 2. Rotor oil pump consists of pump body, pump cover, inner rotor (driving) and outer rotor (driven).

56. What is the function of the oil filter? What are the parts?

Function: circulating oil can be purified before being sent to the surface of moving parts. 1, oil filter There are two types of oil filters: floating type and fixed type. 2. The coarse oil filter is usually connected in series between the oil pump and the main oil circuit, and belongs to the full-flow filter. 3. Fine oil filter This filter has great resistance to the flow of oil, so it is mostly divided into parts and connected in parallel with the main oil circuit. There are two kinds of fine filters: filtration type and centrifugal type.

57. What is the function of crankcase ventilation device? How does it work?

Automobile engines generally have crankcase ventilation devices, so that the mixed gas and waste gas entering the crankcase can be pumped out in time, so that fresh gas enters the crankcase and forms continuous convection. It has the effects of cooling and lowering blood pressure.

Crankcase ventilation generally has two ways, one is natural ventilation and the other is forced ventilation. The gas extracted from the crankcase is introduced into the intake pipe of the engine and sucked into the cylinder for combustion. This ventilation method is called forced ventilation. In this way, the mixed gas escaping into the crankcase can be recovered, which is beneficial to improve the economy of the engine and meets the requirements of environmental protection.