Why do you need to give feedback on the air fuel ratio of a car engine?

Mainly to improve emissions.

Combustion near the theoretical air-fuel ratio (the ratio of the amount of air and fuel that can theoretically make the combustible mixture fully combusted) can make the combustible mixture in the cylinder not only fully combusted, but also reduce the formation of CO and nitrogen oxides formed by exhaust gas, especially insufficient combustion. At the same time, the three-way catalytic converter at the end of the exhaust pipe can also maximize the full reaction of various harmful components in the exhaust gas in this case, and generate harmless CO2 and H2O. (CO2 is a greenhouse gas, but it is a product of full combustion and is better than CO and nitrogen oxides).

Now there are stratified combustion and lean combustion technology, that is, the overall air-fuel ratio can be lower than the theoretical air-fuel ratio of combustion, the main task is to save energy, reduce CO2 emissions, but still involve the problem of air-fuel ratio. Therefore, in any case, the air-fuel ratio must be fed back control.

It is said that the engine is replaced with a small displacement and the carburetor is still used with the original large displacement, then, the carburetor will not be atomized well because the small displacement engine cannot provide enough vacuum, so that the mixture will be dilute during normal operation. However, if you refuel urgently, the accelerator pump will spray more oil than the carburetor with a small displacement, and it will become thicker again.

Ha ha!! When the engine is tilted, the buoyancy of the float in the carburetor decreases. The liquid level will be too high, just as the level of the engine is too high, which will make the mixture too thick.

If the tilt is too severe, the ignition will also be extinguished. When the car rolls over, it often turns off automatically, because the gasoline flows directly from the carburetor, and the mixture is too thick and automatically turns off.

During engine open-loop control, the ECU only determines the amount of fuel injected based on signals such as rotational speed, intake air volume, inlet air pressure and coolant temperature. The air-fuel ratio of the car is controlled by the throttle valve, the throttle is controlled by the foot pedal, and the fuel intake is controlled by the fuel injector. The oxygen sensor is used to detect the ratio, and the computer controls the fuel injector intake, which is the control principle of gasoline vehicles.

In order to meet the requirements of increasingly stringent emission regulations, the most effective way is to use the catalytic purification efficiency of the three-way catalytic converter to exhaust, and the modern electronically controlled gasoline engine implements closed-loop control of the air-fuel ratio in most operating conditions.

Feedback control principle.

In the process of air-fuel ratio feedback control, the change relationship between the air-fuel ratio, the voltage signal output by the oxygen sensor and the air-fuel ratio feedback control signal.

Assuming that the actual air-fuel ratio of the mixture at the beginning is slightly less, the oxygen sensor outputs a high-level signal, and the ECU reduces and corrects the basic fuel injection duration according to the high-level signal of the oxygen sensor, and the actual fuel injection duration is shortened, the fuel injection volume is reduced, and the correction process is carried out in a way that is first fast and then slow.

If you want to brush the program, you need to upgrade the ECU power, adjust the air-fuel ratio, ignition, throttle, pressure, etc. to improve, so it is also related to the regional altitude, etc., you can take a look at the HDP program, the effect is not bad.

The first is the air filter.

Fouling blocks the air intake, resulting in a decrease in the intake air and an over-concentration of the mixture; The second is that the grease nozzle is worn, which cannot be closed when it should be closed, and the oil dripping phenomenon occurs, and the mixture is too thick; The third is the failure of the oil pressure control valve, resulting in too high oil pressure in the system, the same nozzle air intake leakage or not smooth, insufficient fuel pressure, poor work of the fuel injector, low ignition performance, poor gasoline quality, and oxygen sensor.

The detection is inaccurate, the air flow meter is dirty or malfunctioning, and the three-way catalysis.

There are many possibilities under performance, and most of them are caused by poor fuel quality.

The air-fuel ratio of the car is adjusted by the computer on the car, and if you want to adjust the air-fuel ratio, you have to brush the computer hose and throttle valve on the car.

The air chamber and mixing chamber are composed of five parts: the main oil supply device, the idle device, the acceleration device, the concentration device and the starting device. With the more and more precise control of the air-fuel ratio, the dual-chamber carburetor was gradually developed in the later period.

electronically controlled carburetors, etc. <>

The original carburetor gas supply car was all artificially adjusted mixed steam concentration and ignition angle + platinum, and the driving was basically plenary in that era. Now it's EFI oil supply, basically there is no manual knotting, it's all electric annoyance to complete the people who can remember these two devices, are old repairmen. Perhaps, in their memory, this is the real technology.

First, the air filter mechanism blocks the air inlet and reduces the air intake, and the mixture is too slave, and second, the grease nozzle is worn. When it should be closed, it can't be closed, there is a dripping of oil, and the mixture is too thick. Third, the failure of the oil pressure regulating valve causes the oil pressure of the system to be too high, and the same nozzle.

Although the conversion rate of CO and HC.

There is a slight increase, but the conversion rate of NOx drops sharply to 20%, so it is necessary to ensure the best air-fuel ratio, and the key to achieving the best air-fuel ratio is to ensure that the oxygen sensor is working properly. If the fuel contains lead and silicon, it will cause oxygen sensor poisoning.

I think that when the air-fuel ratio of the car is not right, we should find out the cause in time and use more scientific methods to solve this problem.

At this time, it is necessary to check the engine system, then to control the closed-loop oil circuit, and then to check the sensor, and also to check the fuel injector.

It can be dealt with according to the knowledge of the car, and at the same time, the fault and cause of this aspect should also be checked, and finally the correct treatment method should be chosen.

At this time, you can restart the car and light it again, so that the car can be set on fire.

If you want to brush the program, you need to upgrade the ECU power, adjust the air-fuel ratio, ignition, pressure, etc., so it is also related to the regional altitude, etc., you can take a look at the HDP program, and the effect is not bad.

Today's engines are equipped with three-way catalytic converters, which reduce HC+CO and NOx in emissions through redox reactions, and the conversion efficiency is highest when the air-fuel ratio is nearby. An excessively large air-fuel ratio will cause the mixture to be diluted, which will increase NOx emissions. However, if the air-fuel ratio is too small, the mixture will be concentrated, which will increase CO emissions. For a certain type of catalytic converter, it has its own ideal air-fuel ratio window for adaptation, which means that the catalytic converter used in different engines may not be suitable for other models.

Oxygen sensor feedback signal The information is stored in the ECU.

Summary. Feedback control refers to the process of returning the output information of the system to the input terminal, comparing it with the input information, and using the deviation between the two to control. Feedback control is actually using past situations to guide the present and the future.

In the control system, if the effect of the returned information is to cancel out the input information, it is called negative feedback, and negative feedback can stabilize the system; If its function is to enhance the input information, it is called positive feedback, and positive feedback can strengthen the signal.

Does the engine have air-fuel ratio feedback control during start-up and why? Please briefly describe the use of the car engine.

Hello dear. The engine is not controlled by air-fuel ratio feedback during start-up. Under the working conditions of starting, idling, warming, accelerating, and full load of the mobile phone, the engine of the hair and pin code does not work with the theoretical air-fuel ratio, and requires a thick mixture, and the open-loop control is still used.

The air-fuel ratio refers to the mass ratio of air to natural material in the mixture. Expressed in grams of air consumed per gram of material, it is suitable for mechanical engines.

Please briefly describe the reasons for the air-fuel ratio feedback control of the engine and the conditions for its implementation.

Please provide answers to my above questions.

Feedback control refers to the process of returning the output information of the system to the input terminal, comparing it with the input information, and using the deviation between the two to control. In fact, the feedback control of this circle uses the past to guide the present and the future. In the control system, if the function of the returned information is to counteract the collapse of the input information, it is called negative feedback, and negative feedback can make the system tend to be stable; If its function is to enhance the input information, it is called positive feedback, and positive feedback can strengthen the signal.

Engines work in a variety of conditions, from cold starts to late acceleration and deceleration. Different working conditions have different requirements for the air-fuel ratio of the engine. Therefore, the requirements for the air-fuel ratio for various operating conditions will be explained in detail below.

1.Requirements for the air-fuel ratio of the cold start rock group car: the temperature of the engine is low during cold start, and the fuel is not easy to atomize.

Therefore, at this point the engine requires a very thick mixture. 2.Warm-up air-fuel ratio requirements:

After the cold start, in order to quickly bring the engine into the operating temperature, the ECM will increase the engine speed or clear the engine temperature to rise rapidly. At this time, a thick mixture is required. 3.

Idle air-fuel ratio requirements: Due to the small number of mixtures inhaled in the cylinder at idle speed and the poor atomization of gasoline, in order to ensure the normal combustion of the mixture, its concentration must be increased. 4.

Air-fuel ratio requirements for small loads: When the load is small, it is also necessary to provide a concentrated mixture, but the added concentration decreases with the increase of load. 5.

Medium-load air/fuel ratio requirements: At medium-load, the throttle opening is large enough to provide a thinner mixture for optimal fuel consumption. The engine is at medium load most of the operating time.

6.Large-load air-fuel ratio requirements: At heavy load and full load, the throttle opening has exceeded 75%.

At this time, with the increase of throttle opening, the mixture gradually becomes thicker to meet the output requirements of the engine. In fact, when more torque is needed before the throttle is fully opened, it is possible to increase the throttle. For the purpose of fuel consumption, all partial load conditions must be adjusted by means of an economy mixture before the throttle is fully opened.

At full load, however, a power mixture is required for maximum power. 7.Rapid acceleration air-fuel ratio requirements:

During rapid acceleration, the engine needs a lot of power, so the power-to-air-fuel ratio is used, i.e., the concentrated air-to-fuel ratio. 8.Rapid deceleration of air-fuel ratio requirements:

In the event of a sharp deceleration, the engine adopts the oil cut-off control mode. For a short time, the engine computer does not control the injection of fuel injection nozzles. The influence of the air-fuel ratio on the engine dynamics and economy is roughly related to the air-fuel ratio and flame temperature obtained from the engine test, and the relationship between output and fuel consumption is as follows

When the air-fuel ratio is slightly less than the theoretical air-fuel ratio, the flame combustion temperature is the highest, and the engine heats up quickly. When the air-fuel ratio is 12-13, the flame propagation speed is the fastest, and the engine power is the largest, and the air-fuel ratio is also called the power-air-fuel ratio. Due to the increase in the concentration of the mixture, the fuel in the mixture cannot be completely burned, and the fuel consumption of the engine increases significantly.

When the air-fuel ratio is about 16, gasoline burns most completely, engine fuel consumption is the lowest, and the flame temperature and engine power decrease. The air-fuel ratio at this time is called the economic air-fuel ratio. If the mixture is continuously reduced and the lean burn limit is exceeded, a misfire will occur and fuel consumption will increase.

Therefore, increasing engine power and reducing fuel consumption are two contradictory indicators, to increase the power to reduce the economy, and to improve the economy needs to reduce the power. In order to make the engine perform well, the concentration of gasoline engine mixture is usually controlled between the power air-fuel ratio and the economic air-fuel ratio. When the air/fuel ratio is A F18 or A F12, both power and economy are reduced.

Summary. Dear, hello, I am happy to serve you, why there are strict requirements for the air-fuel ratio of the engine The views are as follows: the theoretical air-fuel ratio of various fuels is not the same, for example, theoretically, the air quality required for 1 kg of gasoline to achieve a state of complete combustion is kilograms, so the theoretical air-fuel ratio of gasoline is; 1 kg of diesel fuel needs to achieve the air quality required for complete combustion, so the theoretical air-fuel ratio of diesel is; 1 kg of natural gas needs to achieve the air quality required for complete combustion, so the theoretical air-fuel ratio of natural gas is.

We must not only consider the power and economy of the engine, but also meet the increasingly stringent emission regulations, and control the air-fuel ratio in the high-efficiency area of the three-way catalytic converter as much as possible to reduce the emission of harmful substances and meet the requirements of emission regulations.

Why are there strict requirements for the air-fuel ratio of the engine? Talk about your opinion.

Dear, hello, very high defeat to answer the service for you, why there are strict requirements for the air-fuel ratio of the engine The views are as follows: the theoretical air-fuel ratio of various fuels is not the same, for example, theoretically, 1 kilogram of gasoline to achieve a state of complete aging combustion requires a kilogram of air quality, so the theoretical air-fuel ratio of gasoline is; 1 kg of diesel fuel needs to achieve the air quality required for complete combustion, so the theoretical air-fuel ratio of diesel is; 1 kg of natural gas needs to achieve the air quality required for complete combustion, so the theoretical air-fuel ratio of natural gas is. We must not only consider the power and economy of the engine, but also meet the increasingly stringent emission regulations, and control the air-fuel ratio in the high-efficiency area of the three-way catalytic converter as much as possible to reduce the emission of harmful substances and meet the requirements of emission regulations.

An engine is a machine that can convert other forms of energy into mechanical energy, including internal combustion engines (reciprocating piston engines), external combustion engines (Stirling engines, steam engines, etc.), jet engines, electric bumper machines, etc. For example, the internal combustion engine usually converts chemical energy into mechanical energy. An engine applies to both a power generation unit and an entire machine including a power unit (e.g

gasoline engines, aero engines). The engine was first born in England, so the concept of the engine is also derived from the English language, and its original meaning refers to the "high-round mechanical device that produces power".