The main components of single cylinder gasoline engine and the factors affecting the power performance

The working principle of a single cylinder engine is to ignite the mixed gas in the cylinder, and the explosive gas pushes the piston through the reciprocating linear motion of the piston in the cylinder, so as to realize the crankshaft connecting rod mechanism to drive the crankshaft to rotate. The continuous up and down movement of the piston becomes the continuous rotating movement of the crankshaft, which continuously outputs power to make the engine work normally.

The engine is mainly composed of seven parts: crank connecting rod mechanism, valve mechanism, lubrication system, cooling system, supply system, starting system and ignition system.
The crankshaft connecting rod mechanism is composed of cylinder head, cylinder gasket, cylinder block, oil pan, piston, piston pin, piston ring, connecting rod, crankshaft and flywheel.
The valve mechanism is composed of valve, valve seat, valve spring, valve spring seat, valve oil seal, valve guide, valve door lock plate, timing gear, camshaft, hydraulic tappet and so on.
The lubrication system is composed of oil pump, filter collector, oil filter and so on.
The cooling system is composed of radiator, thermostat, cooling fan and so on.
The supply system is composed of air filter, air flow meter, throttle, intake manifold, fuel tank, fuel pump, fuel filter, carburetor and so on.
The starting system is composed of battery, starting relay, starter, control circuit and so on.
The ignition system is composed of battery, ignition switch, ignition controller, ignition coil, high voltage wire, spark plug and other groups.

Here's a look at some of the key components and factors that have an impact on engine performance

A）Carburetor
Simply put, a carburetor atomizes gasoline and then mixes it with air to form a flammable gas
Take a look at how a carburetor works:

The outside air is filtered and drawn into the carburetor, where the air begins to accelerate through the carburetor narrow and causes its pressure to drop, creating suction at the mouth of the supply line, which sucks the fuel out of the float chamber through the nozzle and atomizes it. The atomized fuel and air are mixed and burned in the cylinder to generate power.
The good working condition of carburetor is the key factor of engine power output and fuel economy. The working state of the carburetor not only depends on the design and manufacturing accuracy, but also closely related to the quality of cleaning and adjustment during use:
1, if the carburetor is improperly adjusted, it may lead to a 10% increase in the flow rate per minute of the main measuring hole, thereby increasing fuel consumption by 5%-7%.
2, if the thickening device valve is not tightly closed, fuel consumption may increase by 10%. When the float fails, fuel consumption may even increase by 2%, and the failure of the carburetor to effectively filter impurities from the gasoline may lead to severe carbon accumulation of valve gaskets and spark plugs.
3, the carburetor float chamber oil level is too low, the combustible mixture into the engine is too thin, the gasoline molecular spacing becomes larger, the combustion speed of the mixture slows down, most of the heat generated by combustion is absorbed by the engine cylinder block, piston, barhead, resulting in engine temperature rise, engine overheating. The engine overheats, reducing the performance of the lubricating oil and accelerating the wear of the parts.
4, the carburetor float chamber oil level is too high, fuel atomization is poor, the combustible mixture is too thick, the mixture can not be completely burned. There is a large amount of carbon deposition in the combustion chamber, the top of the piston, the piston ring groove and the spark plug electrode, which reduces the volume of the combustion chamber and changes the engine compression ratio. Carbon accumulation and high temperature make the crankcase lubricating oil deteriorate, and the engine accelerates the wear of piston ring and cylinder block due to poor lubrication.
Carburetor as a precision mechanical device, its important role in the engine can be called the "heart" of the engine.

B)Piston
A piston is an important part of an engine and is usually made of aluminum or cast iron. The role of the piston is to convert the high-temperature and high-pressure gas generated in the combustion chamber into mechanical energy, and to continuously output power through the connecting rod and the crankshaft

The piston top surface is used to withstand the pressure of high temperature gas, and the piston ring is divided into two kinds of gas ring and oil ring, generally there are two gas rings and one oil ring in each cylinder.
The main role of the gas ring is to seal and heat transfer: seal means to ensure a good seal between the piston and the cylinder wall, prevent the flammable mixture and high temperature gas in the cylinder from leaking into the crankcase, and ensure that the combustible mixture into the engine is compressed enough, and the compression is sufficient, and the combustion is sufficient
The main function of the oil ring is to scrape the excess oil splashed on the cylinder wall when running down, prevent the excess oil from entering the combustion chamber to participate in combustion, and prevent the phenomenon of burning oil; A uniform oil film is applied to the cylinder wall when going up to reduce the wear of the piston, piston ring and cylinder.
The working conditions of the piston ring are extremely harsh, and the force is also very complicated. It is subjected to the action of high temperature and high pressure gas in the cylinder when working, and slides at high speed in the cylinder under conditions of extremely difficult lubrication. Therefore, the material used for manufacturing piston rings should have good wear resistance, thermal conductivity, heat resistance, impact toughness, elasticity and sufficient mechanical strength. At present, the piston ring materials widely used are high quality gray cast iron, ductile cast iron, alloy cast iron and steel strip. It can be said that the piston ring is the engine in the material and processing requirements of the most stringent parts, its service life is the service life of the engine, its material, structure, physical and chemical properties, installation and use have a great impact on the performance of the engine.

C)Crank Connecting Rod Mechanism
The piston group, connecting rod group and crankshaft flywheel group together form the crank connecting rod mechanism, which is the transmission mechanism of the internal combustion engine to achieve the working cycle and complete the energy conversion, is the mechanism of the engine to generate and transmit power, through which the heat energy emitted after the fuel combustion is converted into mechanical energy, is the energy conversion mechanism of the engine. Its working conditions are very bad, to withstand high temperature, high pressure, high speed and chemical corrosion, and to withstand a lot of gas pressure and moving parts of the mass inertia force, so the connecting rod body may be bent and twisted deformation, so the material and structure of the crank linkage mechanism requirements are very high, its structure directly determines the performance and efficiency of the engine.

Crankshaft radius and connecting rod length are important parameters in engine design, which affect the performance and reliability of the engine. Crankshaft radius is usually selected based on factors such as engine displacement and speed, while connecting rod length is related to factors such as cylinder diameter and piston stroke, specifically:
1. Crankshaft radius: The distance between the center of crankshaft rotation and the center of the crank pin is called the crank radius. Its size directly affects the balance of the engine and the size of the rotary inertia force. The crankshaft radius is long, the rotating part is large, and the crankshaft speed is high, so the centrifugal force is large, which may affect the balance and vibration of the engine.
2. Connecting rod length: Connecting rod length refers to the distance between the midpoint of the two connecting rod heads. The design of connecting rod length mainly considers the overall layout and design requirements of the engine, as well as the height of the combustion chamber and the stroke of the piston. The length of the connecting rod has an important effect on the performance of the engine, because it is related to the trajectory of the piston and the compression ratio of the engine.
3. Connecting rod crankshaft ratio: this is the ratio of connecting rod length to crankshaft radius, which affects the speed and acceleration of the piston. Even at the same engine speed, the piston will have different motion characteristics because of the different connecting rod and crankshaft ratio.
In the design of crankshaft and connecting rod, it is also necessary to consider the engine combustion chamber design, piston stroke, crankshaft support mode and balance weight arrangement. In order to ensure the service life and reliability of the connecting rod, it is necessary to carry out strength analysis to determine the key parameters such as stress distribution and maximum stress value of the connecting rod during the working process.
To sum up, the design of crankshaft radius and connecting rod length is a complex engineering problem that requires a comprehensive consideration of many factors to ensure engine performance, efficiency and reliability.

D)Cylinder Compression Ratio
The cylinder is the core component of the engine, he and the piston and cylinder head together to form the combustion chamber, the combustible mixture in the combustion chamber combustion explosion, generating huge downward pressure, pushing the piston downward to produce torque, through the crankshaft output. Its working environment is extremely harsh, the temperature, pressure changes dramatically, need to withstand a large number of thermal load and mechanical load, and has a certain corrosion resistance. Therefore, the cylinder liner is generally cast with high-quality cast iron.

The so-called compression ratio is the ratio of the total volume of the cylinder to the volume of the combustion chamber, so the change of the total volume of the cylinder or the volume of the combustion chamber will cause the change of the compression ratio. The compression ratio of the engine has a great influence on the formation and combustion of the mixture, so it has a great influence on its power and fuel consumption. The reduction of compression ratio will cause incomplete calcination of mixture gas, resulting in decreased engine power and increased fuel consumption; Increasing the compression ratio, although good for improving power, will make the engine work rough. The compression ratio is the degree to which the engine gas mixture is compressed. Therefore, to ensure the appropriate compression ratio, the factors affecting the compression ratio are:
1. The volume of the cylinder head vortex chamber increases, making the compression ratio smaller
2, bearing clearance becomes larger
After a long time of use, the clearance between the main bearing, connecting rod bearing and piston pin and the connecting rod bushing will become larger due to wear, and the piston cannot reach the required top dead center when it goes up, thus reducing the compression ratio. Therefore, the clearance of these bearings should be regularly checked to ensure that it is within the allowable range to avoid the reduction of the compression ratio.
3, the valve depression is too large
Severe wear of the valve or valve seat will cause the valve sag to increase, so that the calcination chamber volume will increase, and the compression ratio will also change. At the same time, do not ignore the valve sag inspection, once the limit is exceeded, it is necessary to replace the new part for repair.
4, connecting rod deformation
Connecting rod bending, twisting or double bending, will also make the piston not reach the required top dead center, so that the compression ratio is reduced. Therefore, in the case of connecting rod deformation, it is necessary to correct it in time.
5, cylinder pad thickness
The material of the cylinder gasket is generally copper asbestos gasket, which has the characteristics of high pressure resistance and high temperature resistance. If the cylinder gasket is too thick, the calcination chamber volume will be larger, thus making the compression ratio smaller.

E) Cylinder Diameter Travel Ratio
Cylinder diameter and stroke are important structural parameters of the engine, which directly determine the engine displacement, compression ratio, power output characteristics and engine size. The larger the cylinder diameter stroke ratio, the engine tends to be high-speed, the faster the engine speed climbs, generally suitable for gasoline engines; The smaller the bore stroke ratio, the more inclined the engine is to low speed, which is generally suitable for the pursuit of low speed and large torque diesel engines.
In the engine, the ratio of the cylinder diameter to the piston stroke is called the cylinder diameter stroke ratio, and there are three modes: the engine with the cylinder diameter greater than the stroke is called the short stroke engine, and the cylinder diameter stroke ratio is greater than 1; The engine whose cylinder diameter is equal to the stroke is called the equal-stroke engine, and the cylinder diameter stroke ratio is equal to 1; An engine with a cylinder diameter less than the stroke is called a long-stroke engine, and the cylinder diameter stroke ratio is less than 1. The power output characteristics of these three engines are different.

F)Camshaft
The camshaft is a part of the engine's valve mechanism, responsible for driving the valve to open and close on time, to ensure that the engine regularly inhales fresh combustible mixture into the cylinder during work, and to discharge the burned exhaust gas from the cylinder in time.

Camshaft design has the following effects on engine fuel efficiency:
1, provide better valve control: the shape of the camshaft and the position of the convex point can determine the opening and closing time of the valve, as well as the lift and fall speed of the valve. By optimizing the camshaft design, more precise valve control can be achieved to ensure that the correct cylinder intake and displacement are introduced at different load and speed conditions, thereby improving fuel efficiency.
2, improve the intake and exhaust flow: the convex shape and arrangement of the camshaft can also affect the opening and closing speed of the valve, which affects the intake and exhaust flow in the cylinder. Through the design of a reasonable camshaft, the air flow dynamics in the cylinder can be improved, the filling efficiency and exhaust efficiency of the combustion chamber can be improved, and the fuel efficiency can be improved
3, control valve overlap: valve overlap is the time difference between the valve opening and closing time. Proper valve overlap can improve exhaust gas recirculation efficiency and reduce emissions, while also helping to improve intake efficiency. The camshaft design can control the size of the valve overlap, and by optimizing the amount of valve overlap, better fuel efficiency can be achieved.
4, reduce mechanical losses: the design of the camshaft will also affect the friction and energy loss of the valve transmission system. By reducing the friction and inertia load of the valve transmission mechanism, the camshaft can reduce additional mechanical losses and improve fuel efficiency.
All in all, camshaft design plays a key role in fuel efficiency by providing better valve control, improving air flow in the cylinder, controlling valve overlap, and reducing mechanical losses.
All in all, the accessories and factors that determine the quality of an engine are quite complex, and only in continuous practice can they be combined into a high-quality engine. As you know, a speed stable at 3100rmp, power between 3.6-3.7, the cylinder head temperature is maintained at 210-220 degrees Celsius, the oil temperature is about 120 degrees Celsius, and the fuel consumption is lower than 390g/kw.h, which is a high-quality 168 power, we can achieve such data by the engine produced by WADE Machinery