49cc engine construction. Points of failure and repair methods

An engine is a complex machine that consists of many mechanisms and systems. Whether it is a gasoline engine, or a diesel engine; Whether it's a four-stroke engine or a two-stroke engine; Whether it's a single-cylinder engine, or a multi-cylinder engine. In order to complete the energy conversion, realize the work cycle, and ensure the continuous normal operation for a long time, the following mechanisms and systems must be in place.

1) Crank linkage mechanism.

The crank linkage mechanism is the main moving part of the engine to realize the working cycle and complete the energy conversion. It is composed of a body group, a piston connecting rod group and a crankshaft flywheel group, etc. In the power stroke, the piston is subjected to gas pressure in a linear motion in the cylinder, which is converted into the rotary motion 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 rotational motion of the crankshaft into the linear motion of the piston.

2) Gas distribution mechanism.

The function of the valve mechanism is to open and close the intake and exhaust valves at regular intervals according to the working sequence and working process of the engine, so that the combustible mixture or air enters the cylinder, and the exhaust gas is discharged from the cylinder to realize the ventilation process. Most of the valve trains adopt overhead valve valve mechanisms, which are generally composed of valve groups, valve transmission groups and valve actuation groups.

3) Fuel supply system.

The function of the fuel supply system of the gasoline engine is to prepare a certain amount and concentration of mixed gas according to the requirements of the engine, supply it to the cylinder, and discharge the exhaust gas after combustion 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 discharge the exhaust gas after combustion.

4) Lubrication system.

The function of the lubrication system is to deliver a certain amount of clean lubricating oil to the surface of the parts in relative motion to achieve liquid friction, reduce frictional resistance, and reduce the wear of parts. and the surface of the part is cleaned and cooled. The lubrication system usually consists of a lubricating oil channel, an oil pump, an oil filter, and some valves.

5) Cooling system.

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 suitable temperature state. The cooling system of a water-cooled engine usually consists of a cooling jacket, a water pump, a fan, a water tank, a thermostat, etc.

6) Ignition system.

In a gasoline engine, the flammable mixture in the cylinder is ignited by an electric spark, for which a spark plug is installed on the cylinder head of the gasoline engine, and the head of the spark plug protrudes into the combustion chamber. All equipment that can generate electric sparks between the spark plug electrodes on time is called an ignition system, which usually consists of a battery, a generator, a distributor, an ignition coil and a spark plug.

7) Starting system.

In order to make the engine transition from a stationary state to a working state, it is necessary to rotate the crankshaft of the engine with external force first, so that the piston can reciprocate, and the combustible mixture in the cylinder burns and expands to work, and pushes the piston to move downward to rotate the crankshaft. The engine can run on its own and the duty cycle can be automatic. Therefore, the whole process from the crankshaft starting to rotate under the action of external force to the engine starting to idle automatically is called the starting of the engine.

The device required to complete the starting process is called the starting system of the engine.

Common faults and maintenance methods of automobile engine Abstract: As an important component in the structure of automobiles, the engine can provide power for the normal operation of automobiles**. However, in combination with the actual situation, in the operation of the car, the engine will frequently fail due to a variety of factors, which seriously affects the sustainable and stable development of China's automobile industry.

1. Common faults of automobiles: the engine cannot be started, common reasons: 1

The circuit is blocked or the battery is out of power. 2.Ignition coil or spark plug failure.

3.The oil circuit is faulty, the oil pump is damaged, and the oil tank is free of oil. Workaround:

If the battery is out of power, you can use the wire or emergency power supply for ignition, and then, it may be a circuit oil circuit failure, it is recommended to send it to the repair shop. 2. Common faults of automobiles: punctures, punctures and other faults, solutions

The puncture tire should be replaced in time, or the tire should be repaired. If it is a flat-proof tire, although you can continue to drive with a flat air, it is still recommended to repair the tire in time. When the tire bursts, remember not to slam on the brakes, slam the direction, hold on to the direction, brake slowly, and deal with it calmly.

After the car is stopped, change the spare tire or contact the rescue. 3. Common faults of automobiles: brake failure, common causes:

1.Maintenance is not in place 2Inadequate operation leads to thermal decay.

Solution: Maintain the brake system. Always check the consumption level of brake discs, brake pads, etc.

Try to avoid applying the brakes for a long time in daily driving, and go downhill in low gear. Avoid overheating the brake pads.

Fourth, the common fault of the car: abnormal noise, common causes: 1

Abnormal body noise. 2.Abnormal engine noise.

Solution: If it is a slight abnormal noise of the car, it is usually caused by insufficient rigidity of the body, which will not affect the driving, but if there is a violent abnormal noise, it is recommended to stop for inspection. The engine screeches are usually caused by timing belts, fan belts, etc.

It is recommended to check the generator, water pump, power steering pump and other accessories. And send it for repair in time.

Common car faults and maintenance tips It is inevitable that there will be such and such problems when the car is driving on the road, so is there no way to avoid these problems? In fact, if you have some understanding of the car, we can still solve some small problems ourselves.

1. Abnormal digestion of lubricating oil.

When a car travels a mileage, the dashboard quickly shows that the lubricant is insufficient, and there are usually 3 reasons:

1.It is possible that there is a problem with the sealing of the engine piston, resulting in too large a gap between the piston and the cylinder wall, and the engine oil is burned.

2.It is possible that the engine parts are severely worn, which makes the gap between the parts too large, resulting in different lubricating oil consumption.

3.The lubricating oil used is not up to standard, resulting in abnormal fuel consumption.

Second, the engine overheating failure.

In operation, it is easy to appear that the coolant temperature is too high, once the cooling temperature exceeds the normal value, the engine can not dissipate heat normally, which will lead to overheating of the engine and affect the normal operation of the engine. The main reasons for abnormal working of the cooling system: thermostat failure, radiator failure, fan not turning, water tank blockage, etc.

The car dashboard prompts that when the coolant temperature is abnormal, you should stop the car to check whether the coolant is leaking. It should be noted that the engine should not be stopped immediately when the car is hot, nor can the coolant be filled immediately, but the engine temperature should be normal before operation. If there is a lot of coolant, the engine thermostat and fan heat dissipation fault should be ruled out.

The common faults of automobile engines are: 1. At various speeds, the muffler emits a rhythmic "abrupt" sound and slightly emits black smoke; 2. The speed cannot be raised to high speed, and the power of the car is obviously insufficient; 3. The engine is not easy to start; It is not easy to speed up (stuffy) after starting, the car is weak to drive, and when accelerating sharply, the carburetor sometimes backfires, and even the engine is easy to stall, and the engine temperature is high; 4. The engine accelerates slowly under idle conditions, but when accelerating sharply, the engine speed cannot be increased, and sometimes the carburetor is tempered; 5. The engine temperature is normal, and it works well at low, medium and high speeds, and after relaxing the accelerator pedal, the speed is too high or the idle speed is unstable or even stalled; 6. The steering wheel trembles at high speed; 7. Deviation when driving. An "engine" is a machine that can convert other forms of energy into mechanical energy, such as internal combustion engines (gasoline engines, etc.), external combustion engines (Stirling engines, steam engines, etc.), electric motors, etc.

There are so many reasons why an engine won't start that it's hard to explain. The leaking pipe on the carburetor you mentioned is not the one at the bottom of the carburetor. If so, it's called an oversized spill deflector, and there is an oil leak here, which indicates that the oil level is high.

Most of the reasons are that there is a foreign body card needle valve in the carburetor, which needs to be disassembled, cleaned and adjusted. Of course, there may be other reasons, but they all need to be disassembled and cleaned for inspection.

There are two situations when the engine fault light is on: (1): the yellow symbol light indicates that the engine is faulty, but the fault does not affect the normal operation of the engine, but it must be maintained; （2）：

The red symbol light indicates that the engine has a serious fault, and it needs to be repaired immediately under normal circumstances, if it is under special road conditions, it can be used in an emergency, but it is necessary to pay attention to the working status of the engine at all times; But as a reminder, EFI engines have self-protection control systems, which will not let you ignore the life and death of the engine;

The main structure of the engine is the fuselage, and other components are installed on the fuselage. It consists of crank connecting rod mechanism, gas distribution mechanism, fuel supply system, lubrication system, cooling system, gasoline engine ignition system, etc. According to the fuel, there are two types of engines: gasoline and diesel engines; There are two types of two-strokes and four-strokes according to the way they work.