What is the function of automobile knock sensor? What is the relationship between a car deflagration

The knock sensor is installed in the middle of the engine block, and the four-cylinder engine is installed between the 2nd and 3rd cylinders, or one between the 1 and 2 cylinders, and one between the 3rd and 4th cylinders. It is used to measure the degree of engine shake, and is used to adjust the ignition advance angle when the engine detonation. Generally, it is piezoelectric ceramic, when the engine is shaking, the ceramic inside is squeezed to produce an electrical signal, because this electrical signal is very weak, so the connection wire of the general detonation sensor is wrapped with shielded wire.

Knock sensors are AC signal generators, but they are very different from most other automotive AC signal generators, in addition to detecting the speed and position of the shaft like magnetoelectric crankshaft and camshaft position sensors, they also detect vibration or mechanical pressure. Unlike stators and magnetoresistors, they are usually piezoelectric devices. They are made of special materials that sense mechanical pressure or vibrations, such as alternating voltages when an engine detonation.

Engine knocking caused by premature ignition, poor exhaust recirculation, and low-grade fuel can cause engine damage. The knock sensor provides a knock signal to the computer (sometimes via a point-controlled modulus) so that the computer can readjust the ignition timing to prevent further knocking. They actually act as "oxygen sensors" that act as feedback control loops for ignition timing.

What is engine super knocking.

Engine "super knocking", also known as low-speed premature ignition, is an abnormal combustion phenomenon unique to supercharged direct-injection gasoline engines. When the engine inhales the mixture of fuel vapor and air, in the process of compression, due to the mixture of low ignition point substances in the fuel, it will cause the gas mixture to automatically deflagrate before the ignition of the spark plug, forming a new ignition point, and the flame spreads outward at a speed several times higher than the normal combustion, so that the cylinder wall is affected and vibrates, which is called detonation. To put it simply, knocking is a manifestation of abnormal pressure in the combustion chamber caused by abnormal combustion.

A phenomenon when detonation occurs.

The engine will emit a crisp and discontinuous metal knocking sound when a slight knock occurs, while a continuous metal knocking sound will occur when the engine will have a continuous metal knocking sound during a severe and continuous knock, and the engine power will also be significantly reduced.

What are the causes of detonation?

1 The air-fuel ratio is incorrect, and the mixture is too dilute to increase the combustion temperature, thereby increasing the engine temperature.

2. The octane number of fuel is too low, the octane number is an indicator of anti-detonation, the higher the octane number, the stronger the anti-detonation, and the lower the conversely, it is easy to detonation.

3. The cleanliness of the fuel is insufficient, and some physical substances and chemical impurities contained in the fuel, including some aromatic substances, will cause spontaneous combustion and detonation during the compression process of the engine.

4. Excessive carbon deposition in the combustion chamber, due to the serious carbon deposition, the actual volume of the cylinder becomes smaller, the compression ratio increases, and at the same time, the carbon deposition in the high-temperature environment will always burn red due to the poor heat dissipation ability, so that the high-temperature compressed mixture is not only ignited by the sequential spark plug, but also randomly ignited by the high-temperature carbon deposition in the cylinder, resulting in detonation.

5. The engine temperature is too high, the engine is too hot in the environment, the inlet air temperature is too high, or the engine cooling water circulation is poor, which will cause the engine to detonate at high temperature.

6 The ignition angle is too early, so that the piston can gain power as soon as it enters the power stroke after the compression stroke is completed, it is usually ignited before the piston reaches the top dead center. Ignition too early will cause most of the oil and gas to burn when the piston is still compressing the stroke, and the unburned oil and gas will be subjected to great pressure and spontaneous combustion, resulting in detonation.

The methods to solve detonation are as follows.

1. Use fuel that conforms to the compression ratio of the engine.

2. Avoid "drag gear" driving.

3. Regularly clean the carbon deposits and fuel injectors in the oil circuit.

4. Avoid high temperatures: check the coolant water level regularly, check and change the engine oil regularly, avoid long-term intense driving, and monitor the water temperature frequently when driving in summer.

5. Appropriate selection of high-quality fuel additives. For example, fuel additives containing PNF stock solution can solve the problem of engine knocking to a certain extent.

Detect engine knocking to suppress the occurrence of knocking phenomena. When the engineer adjusts the knock sensor, the vibration pattern of the knock is written into the electronic control unit. If the knock sensor detects a vibration pattern, the ECU determines the engine knock and then delays the ignition advance angle.

Currently, advanced knock sensors can even tell which cylinder is knocking and delay the ignition advance angle of that cylinder separately. 

The knock sensor is mounted in the middle of the engine block. For example, a four-cylinder engine is installed between cylinders 2 and 3, or one between cylinders 1 and 2 and one between cylinders 3 and 4. It is used to measure engine shake and adjust the ignition advance angle in case of engine knocking.

Usually piezoelectric ceramics. When the engine vibrates, the ceramic inside is squeezed to produce an electrical signal. Because this electrical signal is very weak, the connecting wires of ordinary knock sensors are wrapped with shielded wires.

Knock sensors are AC signal generators, but they are very different from most other AC signal generators in cars. In addition to detecting the speed and position of rotating shafts like magnetoelectric crankshaft and camshaft position sensors, they also detect vibration or mechanical pressure. Unlike stators and magnetoresistors, they are typically piezoelectric devices.

They are made of special materials that can sense mechanical pressure or vibration (for example, when the engine starts knocking, it can generate alternating voltage).

Engine damage can occur due to premature ignition, poor exhaust gas recirculation, and engine knocking caused by low-quality fuel. The knock sensor provides a knock signal to the computer, prompting the computer to readjust the ignition timing to prevent further knocking. They actually act as "oxygen sensors" in the ignition timing feedback control loop.

The working principle of the knock sensor: when the engine vibrates or knocks the cylinder, the piezoelectric ceramic produces a voltage peak, and the greater the knock or vibration, the greater the peak. The engine control unit (ECU) processes the signals received by the detonation sensor, and if a detonation is determined, the ignition is postponed and the detonation continues.

When the engine control unit ECU does not receive the signal from the knock sensor, the ignition time is advanced to ensure the optimal output of the engine. Therefore, the purpose of using a knock sensor is to improve the dynamic performance of the engine without knocking.

Automotive sensors, which used to be used solely in engines, are now being used in chassis, body, and lighting electrical systems. These systems use more than 100 sensors. Among the wide variety of sensors, the common ones are inlet pressure sensors:

Reflects the change in the absolute pressure in the intake manifold and provides a reference signal to the ECU (Engine Electronic Control Unit) to calculate the duration of the injection. Air flow meter: measures the amount of air inhaled by the engine and provides it to the ECU as a reference signal for the injection time; Throttle position sensor: measure the angle of throttle opening, and provide ECU as a reference signal for oil cut-off, control of fuel-air ratio, and ignition advance angle correction; Crankshaft position sensor:

Detect the crankshaft and engine speed, and provide it to the ECU as a reference signal to determine the ignition timing and working sequence;

Automobile knock sensors are usually installed on the generator of the car to detect whether the detonation phenomenon is likely to occur when the engine is started, so as to adjust the ignition advance time through the electronic control system to avoid the occurrence of detonation.

The combustion of the engine is very complex, so it needs to be quite precise design and control, the slightest control error or abnormality, will cause abnormal combustion, and "knocking" is a kind of abnormal combustion. To put it simply, detonation is an abnormal pressure in the combustion chamber caused by abnormal combustion.

When the engine is working, it will cause engine detonation due to the influence of excessive ignition time (ignition early start angle), engine load, temperature and fuel quality. In the event of a knocking, the gas combustion pin bursts before the piston moves to the top dead center, causing noise and reducing the power of the engine engine, and damaging the mechanical parts of the engine. In order to prevent knocking, the knock sensor is an indispensable and important component in order to adjust the ignition advance time through the electronic control system.

There are many types of knock sensors, such as magnetostrictive knock sensors, piezoelectric ceramic knock sensors, piezoelectric resonance sensors, etc.

In order to better avoid further knocking of the engine, it has the protagonist of today's car knock sensor. But there are still some friends who don't know it very deeply, and even don't even know the name. So, what is the function of the car knock sensor, let's give you a look.

The automobile knock sensor is actually a device used to check engine deflagration. In the event of an engine deflagration (causing chatter), the knock sensor changes the vibration analysis of the engine to the operating voltage of the data signal, and the feedback is fed back to the vehicle's on-board computer (ECU). At this time, the ECU will immediately adjust the ignition timing according to the data information stored in advance and the feedback from the opinions, thereby reducing the probability of deflagration of the car.

You can't underestimate the existence of the car knock sensor, once there is a problem, of course, you can't test the engine deflagration. Even if the engine has already detonated, the ECU cannot adjust the ignition timing on time to prevent further detonation, and the direct impact on the engine is extremely large. Naturally, with the continuous development of high-tech technology, the ECU of contemporary automobile engines has long considered this situation in the case of formulation.

Therefore, if the data signal of the knock sensor cannot be detected for a long time, the maintenance program will be automatically opened to prevent knocking, and the fault indicator will continue to flash to alert the buyer.

Millions of car purchase subsidies.