Natural gas engine knocking control method and natural gas engine

Abstract

The invention relates to a natural gas engine knock control method and a natural gas engine, single-cylinder knock analysis is performed on each cylinder according to the cylinder pressure of each cylinder and the rotating speed and load of the natural gas engine, and then single-cylinder gas inlet phase adjustment is performed on each cylinder according to the knock analysis result of each cylinder, so that the knock of the natural gas engine is controlled. The non-uniformity of each cylinder of the natural gas engine is fully considered, and each cylinder of the natural gas engine is accurately controlled, so that the knocking of each cylinder is greatly reduced, the working efficiency of the natural gas engine is greatly improved, the natural gas engine is prevented from being damaged due to knocking, and the service life of the natural gas engine is prolonged. The service life of the natural gas engine is prolonged.

Description

Technical Field

[0001] The present application relates to the technical field of natural gas engines, and in particular to a method for controlling knock in a natural gas engine and a natural gas engine. Background Art

[0002] Knock in natural gas engines has long been the main bottleneck for improving its economy and power. Knock can lead to reduced engine power, increased fuel consumption, increased noise, poor vehicle comfort, and worse emissions. In the most serious cases, it can cause knocking in the cylinder and damage the engine's mechanical parts.

[0003] However, the existing method of controlling knock in natural gas engines is to control knock by uniformly regulating each cylinder of the natural gas engine. However, it does not take into account the impact of the unevenness of each cylinder of the engine and cannot perform a single regulation on different cylinders, resulting in poor control of knock in the natural gas engine. Summary of the invention

[0004] Based on this, it is necessary to provide a method for controlling knock in a natural gas engine and a natural gas engine to address the problem that the existing natural gas engine cannot perform single regulation on different cylinders, resulting in poor control effect on knock in the natural gas engine. In a first aspect, an embodiment of the present application provides a method for controlling knock in a natural gas engine, and the method for controlling knock in a natural gas engine includes:

[0005] Obtain the speed and load of the natural gas engine;

[0006] Get the cylinder pressure of each cylinder;

[0007] According to the cylinder pressure of each cylinder and the speed and load of the natural gas engine, a single cylinder knock analysis is performed on each cylinder;

[0008] According to the knock analysis result of each cylinder, single cylinder intake phase adjustment is performed on each cylinder respectively.

[0009] In one of the embodiments, the single-cylinder intake phase is divided into a plurality of intake timing modes, and the closing timings of the intake valves in the plurality of intake timing modes are different from each other.

[0010] In one embodiment, the plurality of single-cylinder intake phases include a first intake valve timing mode, a second intake valve timing mode, and a third intake valve timing mode;

[0011] In the first intake valve distribution mode, the intake valve is controlled to open in the range of 0°-15°CA before the top dead center of the exhaust stroke, and to close in the range of 20°-35°CA before the bottom dead center of the intake stroke;

[0012] In the second intake valve timing mode, the intake valve is controlled to open in the range of 0°-15°CA before the top dead center of the exhaust stroke, and to close in the range of 35°-50°CA before the bottom dead center of the intake stroke;

[0013] In the third intake valve timing mode, the intake valve is controlled to open in the interval of 0°-15°CA before the top dead center of the exhaust stroke, and to close in the interval of 50°-70°CA before the bottom dead center of the intake stroke.

[0014] In one embodiment, the natural gas engine knock control method further includes:

[0015] Before the step of obtaining the cylinder pressure of each cylinder, determine whether the engine load is greater than 85%. If so, continue to analyze the cylinder pressure of each cylinder. When the cylinder pressure of the cylinder is lower than the preset pressure range, the ignition timing is advanced, the first intake valve timing mode is turned on, and the mixture concentration is increased to increase the cylinder pressure of the cylinder to within the preset pressure range.

[0016] In one embodiment, the natural gas engine knock control method further includes:

[0017] Before the step of obtaining the cylinder pressure of each cylinder, determine whether the engine load is greater than 85%. If so, continue to analyze the cylinder pressure of each cylinder. When the cylinder pressure of the cylinder exceeds the preset pressure range, the ignition timing is delayed, the second intake valve timing mode is turned on, and the mixture concentration is reduced to reduce the cylinder pressure of the cylinder to within the preset pressure range.

[0018] In one embodiment, the natural gas engine knock control method further includes:

[0019] Before the step of obtaining the cylinder pressure of each cylinder, determine whether the engine load is less than or equal to 85% and greater than or equal to 70%. If so, continue to analyze the cylinder pressure of each cylinder. When the cylinder pressure of the cylinder is lower than the preset pressure range, the ignition timing is advanced and the second intake valve mode is turned on to increase the cylinder pressure of the cylinder to within the preset pressure range.

[0020] In one embodiment, the natural gas engine knock control method further includes:

[0021] Before the step of obtaining the cylinder pressure of each cylinder, determine whether the engine load is less than or equal to 85% and greater than or equal to 70%. If so, continue to analyze the cylinder pressure of each cylinder. When the cylinder pressure of the cylinder is higher than the preset pressure range, turn on the third intake valve timing mode and reduce the mixture concentration so that the cylinder pressure of the cylinder is reduced to within the preset pressure range.

[0022] In one embodiment, the natural gas engine knock control method further includes:

[0023] Before the step of obtaining the cylinder pressure of each cylinder, the single-cylinder knock analysis step includes analyzing the engine load level to determine whether the engine load is less than or equal to 70%. If so, the third intake valve timing mode is activated.

[0024] In a second aspect, an embodiment of the present application further provides a natural gas engine for implementing the above-mentioned natural gas engine knock control method, comprising:

[0025] A cylinder pressure sensor, wherein there are a plurality of cylinder pressure sensors, and the plurality of cylinder pressure sensors are respectively installed in different cylinders, and the cylinder pressure sensor is used to detect the cylinder pressure of the cylinder;

[0026] An electronic control unit is electrically connected to the cylinder pressure sensor, and is used to receive the detection result of the cylinder pressure sensor. The electronic control unit is used to perform knock analysis on each cylinder according to the detection result of each cylinder pressure sensor and the speed and load of the natural gas engine, and to adjust the single-cylinder intake phase of each cylinder according to the knock analysis result.

[0027] In one embodiment, the natural gas engine also includes a storage unit, which is electrically connected to the electronic control unit. The storage unit stores a preset pressure range. The electronic control unit is used to adjust the intake valve mode of each cylinder based on the comparison between the detection result of the cylinder pressure sensor on the cylinder and the preset pressure range stored in the storage unit.

[0028] The embodiment of the present application provides a method for controlling knock in a natural gas engine and a natural gas engine. Through the cylinder pressure of each cylinder and the speed and load of the natural gas engine, a single-cylinder knock analysis is performed on each cylinder respectively, and then according to the knock analysis result of each cylinder, the single-cylinder intake phase of each cylinder is adjusted respectively, so as to perform targeted adjustments for different cylinders, fully consider the unevenness of each cylinder of the natural gas engine, and realize precise control of each cylinder of the natural gas engine, thereby greatly reducing the knock of each cylinder, greatly improving the working efficiency of the natural gas engine, avoiding damage to the natural gas engine due to knock, and increasing the service life of the natural gas engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A flow chart of a method for controlling knock in a natural gas engine provided in some embodiments of the present application.

[0030] Figure 2 A subsequent flow chart of a method for controlling knock in a natural gas engine provided in some embodiments of the present application.

[0031] Figure 3 A schematic diagram of the single-cylinder intake phase of a natural gas engine knock control method provided in some embodiments of the present application. DETAILED DESCRIPTION

[0032] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0033] In the description of the present application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0034] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0035] In this application, unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0036] In the present application, unless otherwise clearly specified and limited, if there is a description that a first feature is "above" or "below" a second feature, etc., or similar descriptions appear, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0037] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only implementation method.

[0038] See also Figure 1-Figure 3 An embodiment of the present application provides a method for controlling knock in a natural gas engine. The method for controlling knock in a natural gas engine includes:

[0039] S100, obtaining the speed and load of the natural gas engine;

[0040] S200, obtaining the cylinder pressure of each cylinder;

[0041] S300, performing a single cylinder knock analysis on each cylinder according to the cylinder pressure of each cylinder and the speed and load of the natural gas engine;

[0042] S400: According to the knock analysis result of each cylinder, adjust the single cylinder intake phase of each cylinder.

[0043] The embodiment of the present application provides a method for controlling knock in a natural gas engine. Through the cylinder pressure of each cylinder and the speed and load of the natural gas engine, a single-cylinder knock analysis is performed on each cylinder respectively. Then, according to the knock analysis result of each cylinder, the single-cylinder intake phase of each cylinder is adjusted respectively, so as to perform targeted adjustments for different cylinders, fully consider the unevenness of each cylinder of the natural gas engine, and realize precise control of each cylinder of the natural gas engine, thereby reducing the knock of each cylinder, greatly improving the working efficiency of the natural gas engine, avoiding damage to the natural gas engine due to knock, and increasing the service life of the natural gas engine.

[0044] like Figure 1 and Figure 2As shown, in some embodiments, the exhaust phase of a single cylinder is divided into a plurality of intake valve timing modes, and the closing timings of the intake valves in the plurality of intake valve timing modes are different from each other.

[0045] In multiple intake valve timing modes, the cylinder intake valve opening time is located before the cylinder exhaust stroke top dead center to reduce intake resistance. In multiple intake valve timing modes, the intake valve closing time is located after the intake stroke bottom dead center, so that part of the mixture entering the cylinder returns to the intake pipe, that is, the actual mixture volume is smaller than the cylinder volume, the actual compression ratio is smaller than the cylinder geometric compression ratio, and the expansion ratio is greater than the actual compression ratio, saving fuel.

[0046] In addition, the difference between multiple intake valve distribution modes is that the closing time of the intake valve is different. It can be understood that the later the intake valve is closed, the more the mixed gas returns to the intake pipe, the smaller the actual compression ratio, the lower the temperature at the end of compression, and the lower the knock tendency. At the same time, the higher the pressure at the intake pipe, the lower the intake loss. By setting multiple intake valve distribution modes with different closing times, it is possible to adapt to the intake needs under different working conditions and greatly reduce the knock tendency of natural gas engines.

[0047] like Figure 1 and Figure 2 As shown, in some embodiments, the plurality of intake air distribution modes include a first intake air distribution mode, a second intake air distribution mode, and a third intake air distribution mode;

[0048] In the first intake valve timing mode, the intake valve of the control cylinder is opened in the range of 0°-15° CA (Crank Angle, engine crankshaft angle) before the top dead center of the cylinder's exhaust stroke, and is closed in the range of 20°-35° CA before the bottom dead center of the cylinder's intake stroke;

[0049] In the second intake valve timing mode, the intake valve of the control cylinder is opened in the range of 0°-15°CA before the top dead center of the exhaust stroke of the cylinder, and is closed in the range of 35°-50°CA before the bottom dead center of the intake stroke of the cylinder;

[0050] In the third intake valve timing mode, the intake valve of the control cylinder is opened in the range of 0°-15°CA before the top dead center of the exhaust stroke of the cylinder, and is closed in the range of 50°-70°CA before the bottom dead center of the intake stroke of the cylinder.

[0051] Among the first intake valve timing mode, the second intake valve timing mode and the third intake valve timing mode, the intake valve closing time of the first intake valve timing mode is the earliest, so the actual compression ratio is the largest, the intake volume is the largest, and the knock tendency is the largest. The intake valve closing time of the second intake valve timing mode is later than the intake valve closing time of the first intake valve timing mode, and the intake valve closing time of the third intake valve timing mode is the latest, so the actual compression ratio is the smallest, the intake volume is the smallest, and the knock tendency is the smallest. At the same time, during the power stroke, the expansion ratio is greater than the compression ratio, thereby improving the economy of the engine. By switching different intake valve timing modes according to the actual needs of the natural gas engine, the knock of the natural gas engine can be controlled, thereby greatly improving the working efficiency of the natural gas engine, avoiding damage to the natural gas engine due to knock, and increasing the service life of the natural gas engine.

[0052] like Figure 2 and Figure 3 As shown, in some embodiments, the method for controlling knock in a natural gas engine further includes:

[0053] Before obtaining the cylinder pressure of each cylinder, determine whether the engine load is greater than 85%. If so, continue to analyze the cylinder pressure of each cylinder. When the cylinder pressure of the cylinder is lower than the preset pressure range, the ignition timing is advanced, the first intake valve mode is turned on, and the mixture concentration is increased to increase the cylinder pressure of the cylinder to within the preset pressure range.

[0054] When the natural gas engine is under high load, the natural gas engine adopts the power mode and continues to detect the cylinder pressure. When the cylinder pressure is lower than the preset pressure range, the ignition timing is advanced, the first intake valve mode is turned on, and the mixture concentration is increased to reduce the cylinder pressure to within the preset pressure range, thereby greatly improving the single-cylinder power of the natural gas engine and thus improving the power of the entire engine.

[0055] It should be noted that the load of a natural gas engine is the ratio of the power generated by the natural gas engine at a certain speed to the maximum power that can be generated at the same speed, expressed as a percentage.

[0056] The preset pressure range in the embodiment of the present application is between ±3 bar, and the preset pressure range in the embodiment of the present application can be adjusted according to the specific natural gas engine.

[0057] In addition, advancing the ignition timing means changing the ignition advance angle, which means that the spark plug sparks before the piston reaches the compression top dead center, igniting the combustible mixture in the combustion chamber. The angle that the crankshaft rotates during the period from the ignition moment to the piston reaching the compression top dead center is called the ignition advance angle. In addition, the ignition advance angle that enables the natural gas engine to obtain the best power, economy and best emissions is called the optimal ignition advance angle. In the embodiment of the present application, the natural gas engine obtains the best power and economy by adjusting the ignition advance angle to the optimal ignition advance angle.

[0058] In addition, increasing the concentration of the mixed gas is to add the mixed gas into the cylinder, thereby increasing the concentration of the mixed gas in the cylinder, and then achieving an increase in the cylinder pressure in the cylinder.

[0059] like Figure 2 and Figure 3 As shown, in some embodiments, the method for controlling knock in a natural gas engine further includes:

[0060] Before obtaining the cylinder pressure of each cylinder, determine whether the engine load is greater than 85%. If so, continue to analyze the cylinder pressure of each cylinder. When the cylinder pressure of the cylinder exceeds the preset pressure range, the ignition timing is delayed, the second intake valve mode is turned on, and the mixture concentration is reduced to reduce the cylinder pressure of the cylinder to within the preset pressure range.

[0061] When the natural gas engine is under high load, the natural gas engine adopts the power mode and continues to detect the cylinder pressure. When the cylinder pressure is higher than the preset pressure range, the risk of knocking is greatly increased. Therefore, the second intake valve timing mode is adopted to appropriately reduce the actual compression ratio to avoid knocking. Under the premise of avoiding knocking, both power and fuel economy can be taken into account.

[0062] like Figure 2 and Figure 3 As shown, in some embodiments, the method for controlling knock in a natural gas engine further includes:

[0063] Before obtaining the cylinder pressure of each cylinder, determine whether the engine load is less than or equal to 85% and greater than or equal to 70%. If so, continue to analyze the cylinder pressure of each cylinder. When the cylinder pressure of the cylinder is lower than the preset pressure, the ignition timing is advanced and the second intake valve mode is turned on to increase the cylinder pressure of the cylinder to within the preset pressure range.

[0064] When the natural gas engine is at medium load, the power requirement of the natural gas engine is reduced, and the engine enters the economy priority mode and continues to detect the cylinder pressure. When the cylinder pressure is lower than the preset pressure range, the second intake valve mode is used, and the power requirement is increased. The intake volume is also increased, taking into account the power while ensuring fuel economy.

[0065] like Figure 2 and Figure 3 As shown, in some embodiments, the method for controlling knock in a natural gas engine further includes:

[0066] Before obtaining the cylinder pressure of each cylinder, determine whether the engine load is less than or equal to 85% and greater than or equal to 70%. If so, continue to analyze the cylinder pressure of each cylinder. When the cylinder pressure of the cylinder is higher than the preset pressure, turn on the third intake valve timing mode and reduce the mixture concentration to reduce the cylinder pressure to within the preset pressure range.

[0067] When the natural gas engine load is medium load, at this time, the natural gas engine's power requirements are weakened, the engine enters the economy priority mode, and continues to detect the cylinder pressure of the cylinder. When the cylinder pressure of the cylinder is higher than the preset pressure range, the risk of knock is relatively large, so the third intake valve timing mode is adopted. The intake valve closing time of the third intake valve timing mode is later than the intake valve closing time of the third intake valve timing mode. Therefore, the actual compression ratio is small, the intake volume is small, and the knock tendency is minimal. At the same time, in the power stroke, the expansion ratio is greater than the compression ratio, thereby improving the engine economy and reducing the risk of knock, avoiding damage to the natural gas engine due to knock, and increasing the service life of the natural gas engine.

[0068] like Figure 2 and Figure 3 As shown, in some embodiments, the method for controlling knock in a natural gas engine further includes:

[0069] Before the step of obtaining the cylinder pressure of each cylinder, it is determined whether the engine load is less than 70%. If so, the third intake valve timing mode is started.

[0070] When the engine is under low load, the power requirement is low, and a smaller intake volume can meet the demand. Therefore, the third intake valve mode is used in the low load area, and its intake volume is the lowest to ensure fuel economy. In addition, the volume of air returning to the intake pipe is the highest in the third intake valve mode, so the intake pressure is the highest, which can reduce the throttle throttling and reduce the supercharger boost.

[0071] In a second aspect, an embodiment of the present application further provides a natural gas engine, which is used to implement the above-mentioned natural gas engine knock control method, including:

[0072] Cylinder pressure sensor: there are multiple cylinder pressure sensors, which are installed in different cylinders respectively. The cylinder pressure sensor is used to detect the cylinder pressure of the cylinder;

[0073] The electronic control unit is electrically connected to the cylinder pressure sensor. The electronic control unit is used to receive the detection result of the cylinder pressure sensor. The electronic control unit is used to perform knock analysis on each cylinder according to the detection result of each cylinder pressure sensor and the speed and load of the natural gas engine, and adjust the single cylinder intake phase of each cylinder according to the knock analysis result.

[0074] A natural gas engine provided in an embodiment of the present application can cooperate with the above-mentioned natural gas engine knock control method to perform single control on each cylinder inside the natural gas engine, detect the cylinder pressure of each cylinder through a cylinder pressure sensor, and perform single-cylinder knock analysis on each cylinder according to the detected speed and load of the natural gas engine, and the cylinder pressure of each cylinder, and then adjust the single-cylinder intake phase of each cylinder according to the knock analysis result of each cylinder, so as to perform targeted adjustments for different cylinders, fully consider the unevenness of each cylinder of the natural gas engine, and achieve precise control of each cylinder of the natural gas engine, thereby greatly reducing the knock of each cylinder, greatly improving the working efficiency of the natural gas engine, avoiding damage to the natural gas engine due to knock, and increasing the service life of the natural gas engine.

[0075] In some embodiments, the natural gas engine also includes a storage unit, which is electrically connected to the electronic control unit. The storage unit stores a preset pressure range. The electronic control unit is used to adjust the intake valve mode of each cylinder based on the comparison of the cylinder pressure sensor's detection result on the cylinder with the preset pressure range stored in the storage unit.

[0076] By storing the preset pressure range in the storage unit, the electronic control unit can compare the cylinder pressure sensor's detection result on the cylinder with the preset pressure range stored in the storage unit, and then the electronic control unit can automatically adjust the intake and valve timing mode of each cylinder, thereby greatly improving the working efficiency of the natural gas engine.

[0077] The preset pressure range in the embodiment of the present application can be adjusted according to the specific natural gas engine.

[0078] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0079] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A method for controlling knock in a natural gas engine, characterized in that: The natural gas engine knock control method comprises: Obtain the speed and load of the natural gas engine; Get the cylinder pressure of each cylinder; According to the cylinder pressure of each cylinder and the speed and load of the natural gas engine, performing a single cylinder knock analysis on each cylinder; According to the knock analysis result of each cylinder, single cylinder intake phase adjustment is performed on each cylinder respectively.

2. The method for controlling knock of a natural gas engine according to claim 1, characterized in that: The single-cylinder intake phase is divided into a plurality of intake timing modes, and the intake valve closing timings of the plurality of intake timing modes are different from each other.

3. The method for controlling knock of a natural gas engine according to claim 2, characterized in that: The plurality of single-cylinder intake phases include a first intake valve timing mode, a second intake valve timing mode and a third intake valve timing mode; In the first intake valve distribution mode, the intake valve of the cylinder is controlled to open in the interval of 0°-15°CA before the top dead center of the exhaust stroke of the cylinder, and to close in the interval of 20°-35°CA before the bottom dead center of the intake stroke of the cylinder; In the second intake valve timing mode, the intake valve of the cylinder is controlled to open in the interval of 0°-15°CA before the top dead center of the exhaust stroke of the cylinder, and to close in the interval of 35°-50°CA before the bottom dead center of the intake stroke of the cylinder; In the third intake valve timing mode, the intake valve of the cylinder is controlled to open in the interval of 0°-15°CA before the top dead center of the exhaust stroke of the cylinder, and to close in the interval of 50°-70°CA before the bottom dead center of the intake stroke of the cylinder.

4. The method for controlling knock of a natural gas engine according to claim 3, characterized in that: The natural gas engine knock control method further includes: Before the step of obtaining the cylinder pressure of each cylinder, determine whether the engine load is greater than 85%. If so, continue to analyze the cylinder pressure of each cylinder. When the cylinder pressure of the cylinder is lower than the preset pressure range, the ignition timing is advanced, the first intake valve timing mode is turned on, and the mixture concentration is increased to increase the cylinder pressure of the cylinder to within the preset pressure range.

5. The method for controlling knock of a natural gas engine according to claim 3, characterized in that: The natural gas engine knock control method further includes: Before the step of obtaining the cylinder pressure of each cylinder, determine whether the engine load is greater than 85%. If so, continue to analyze the cylinder pressure of each cylinder. When the cylinder pressure of the cylinder exceeds the preset pressure range, the ignition timing is delayed, the second intake valve timing mode is turned on, and the mixture concentration is reduced to reduce the cylinder pressure of the cylinder to within the preset pressure range.

6. The method for controlling knock of a natural gas engine according to claim 3, characterized in that: The natural gas engine knock control method further includes: Before the step of obtaining the cylinder pressure of each cylinder, determine whether the engine load is less than or equal to 85% and greater than or equal to 70%. If so, continue to analyze the cylinder pressure of each cylinder. When the cylinder pressure of the cylinder is lower than the preset pressure range, the ignition timing is advanced and the second intake valve mode is turned on to increase the cylinder pressure of the cylinder to within the preset pressure range.

7. The method for controlling knock of a natural gas engine according to claim 3, characterized in that: The natural gas engine knock control method further includes: Before the step of obtaining the cylinder pressure of each cylinder, determine whether the engine load is less than or equal to 85% and greater than or equal to 70%. If so, continue to analyze the cylinder pressure of each cylinder. When the cylinder pressure of the cylinder is higher than the preset pressure range, turn on the third intake valve timing mode and reduce the mixture concentration so that the cylinder pressure of the cylinder is reduced to within the preset pressure range.

8. The method for controlling knock of a natural gas engine according to claim 3, characterized in that: The natural gas engine knock control method further includes: Before the step of obtaining the cylinder pressure of each cylinder, it is determined whether the engine load is less than or equal to 70%. If so, the third intake valve timing mode is turned on.

9. A natural gas engine, characterized in that: The implementation of the method for controlling knock in a natural gas engine according to any one of claims 1 to 8 comprises: A cylinder pressure sensor, wherein there are a plurality of cylinder pressure sensors, and the plurality of cylinder pressure sensors are respectively installed in different cylinders, and the cylinder pressure sensor is used to detect the cylinder pressure of the cylinder; An electronic control unit is electrically connected to the cylinder pressure sensor, and is used to receive the detection result of the cylinder pressure sensor. The electronic control unit is used to perform knock analysis on each cylinder according to the detection result of each cylinder pressure sensor and the speed and load of the natural gas engine, and to adjust the single-cylinder intake phase of each cylinder according to the knock analysis result.

10. The natural gas engine according to claim 9, characterized in that: The natural gas engine also includes a storage unit, which is electrically connected to the electronic control unit. The storage unit stores a preset pressure range. The electronic control unit is used to adjust the intake valve timing mode of each cylinder based on the comparison between the detection result of the cylinder pressure sensor on the cylinder and the preset pressure range stored in the storage unit.

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