A control method and system for injection frequency of a direct injection engine and a vehicle

Abstract

The application discloses a control method of injection times of a direct injection engine, which comprises the following steps: dividing engine working conditions into a starting mode, a catalyst light-off mode, a warm-up mode and a normal operation mode, determining the combustion injection times in the four modes; establishing injection time tables in the four modes; judging the engine working condition according to the priority of the four modes; the priority of the four modes is lower and lower; in the case that the combustion mode changes or does not change, determining the final combustion injection times according to the injection time tables in the four modes and the engine speed. The application also provides a system and a car. The application controls the injection times of the direct injection engine by fully considering the engine working conditions and environmental transient changes and the engine speed fluctuation, so as to avoid the engine speed fluctuation caused by the injection time fluctuation and to influence the emission and fuel economy.

Description

Technical Field

[0001] This invention relates to the field of engine control, and more specifically to a method, system, and automobile for controlling the number of injections in a direct injection engine. Background Technology

[0002] A direct injection engine is an engine that operates by injecting fuel directly into the cylinder. To reduce engine vibration and noise, and improve performance such as cold starts and emissions, different injection frequencies are required depending on the engine's operating conditions. Currently, the injection frequency is commonly determined by engine speed, fuel injection quantity, battery voltage, and coolant temperature. There is also considerable research on the injection frequency of direct injection engines.

[0003] The patent, with publication number CN112096535A, entitled "A Method, System and Automobile for Controlling the Number of Fuel Injections in an Engine," proposes a method for controlling the number of injections under different combustion modes. However, this method does not take into account the problem that fluctuations in the number of injections caused by engine speed fluctuations, in turn, exacerbate speed fluctuations.

[0004] The patent with publication number CN110107419A, entitled "A Method and System for Determining the Number of Fuel Injections," optimizes the number of injections by adding the temperature and temperature change rate of the drive chip to prevent damage to the chip due to excessive injection frequency. However, this method does not consider the impact of transient changes in engine operating conditions and the environment, which can cause fluctuations in the number of injections, leading to fluctuations in engine speed, affecting emissions and fuel economy.

[0005] Therefore, we urgently need a new method for controlling the number of injections in direct injection engines. Summary of the Invention

[0006] The main objective of this invention is to provide a method, system, and vehicle for controlling the number of injections in a direct injection engine. This method fully considers the engine operating conditions and transient changes in the environment, as well as engine speed fluctuations, to control the number of injections in the direct injection engine, so as to avoid engine speed fluctuations caused by injection frequency fluctuations, which would affect emissions and fuel economy.

[0007] The technical solution adopted in this invention is:

[0008] A method for controlling the number of injections in a direct injection engine, comprising the following steps:

[0009] The engine operating conditions are divided into starting mode, catalytic converter ignition mode, warm-up mode, and normal operation mode. The number of combustion injections in each of the four modes is determined. The number of combustion injections in starting mode is denoted as CNT. Injection1Raw The number of combustion injections in catalytic converter ignition mode is CNT. Injection2Raw The number of combustion injections in warm-up mode is CNT.Injection3Raw The number of combustion injections in normal operating mode is CNT. Injection4Raw Establish a table of the number of sprays under four modes;

[0010] The engine's operating condition is determined by the priority of the four modes; the priority of the four modes decreases from one to the next.

[0011] In cases where the combustion mode changes or remains unchanged, the final number of combustion injections is determined based on the injection frequency table for the four modes and the engine speed.

[0012] The present invention also provides an engine fuel injection frequency control system for executing the above-described engine fuel injection frequency control method.

[0013] The present invention also provides an automobile that includes the above-described engine fuel injection frequency control system.

[0014] The beneficial effects of this invention are as follows:

[0015] Different injection frequencies are proposed based on different operating conditions and objectives. The working mode and injection frequency are optimized to improve problems such as speed fluctuation caused by injection frequency fluctuation. At the same time, the injection frequency is optimized in real time according to different engine life cycles.

[0016] This invention fully considers engine operating conditions (starting mode, catalyst ignition mode, warm-up mode and normal operation mode) and transient environmental changes (changes in combustion mode, no change in combustion mode), as well as engine speed fluctuations to control the number of injections in a direct injection engine. This can avoid the problems of engine speed fluctuations caused by fluctuations in the number of injections, which affect emissions and fuel economy.

[0017] The warm-up mode judgment is optimized to improve engine speed fluctuations during the warm-up process, thereby accurately controlling the number of injections by the direct injection engine during the warm-up process. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart illustrating the method for controlling the number of injections in a direct injection engine.

[0020] Figure 2 This is a schematic diagram of the warm-up mode determination process;

[0021] Figure 3 It is to determine the warm-up coefficient r WarmUp A flowchart. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0023] Example 1

[0024] See Figures 1-3 A method for controlling the number of injections in a direct injection engine, comprising the following steps:

[0025] The engine operating conditions are divided into starting mode, catalytic converter ignition mode, warm-up mode, and normal operation mode. The number of combustion injections in each of the four modes is determined. The number of combustion injections in starting mode is denoted as CNT. Injection1Raw The number of combustion injections in catalytic converter ignition mode is CNT. Injection2Raw The number of combustion injections in warm-up mode is CNT. Injection3Raw The number of combustion injections in normal operating mode is CNT. Injection4Raw Establish a table of the number of sprays under four modes;

[0026] The engine's operating condition is determined by the priority of the four modes; the priority of the four modes decreases from one to the next.

[0027] In cases where the combustion mode changes or remains unchanged, the final number of combustion injections is determined based on the injection frequency table for the four modes and the engine speed.

[0028] Specifically:

[0029] The engine operating conditions are divided into four modes: starting mode, catalytic converter ignition mode, warm-up mode, and normal operation mode. The priority of these four modes decreases from one to the next.

[0030] 1. Starting mode: This refers to the engine starting phase, during which the number of combustion injections (CNT) is designed based on emissions and to improve engine combustion stability. Injection1Raw This section is based on patent number 202010813483.2, entitled "Engine Fuel Injection Frequency Control Method, System, and Automobile." The injection frequency in starting mode (injection frequency table in starting mode) is as follows:

[0031]

[0032] 2. Catalytic converter light-off mode: When the catalytic converter light-off control is activated, the combustion injection count CNT is designed based on the purpose of increasing the exhaust gas temperature, improving emissions, and enhancing the combustion stability of the engine. Injection2Raw This part can be obtained from the patent with the patent number 202010813483.2 and the patent title "Engine Fuel Injection Count Control Method, System, and Vehicle"; specifically:

[0033] The injection count table in the catalytic converter light-off mode is as follows:

[0034]

[0035]

[0036] 3. Warm-up mode: The combustion injection count is designed based on the purpose of increasing the coolant temperature, improving emissions, and enhancing the combustion stability of the engine. In this embodiment, the warm-up mode determination is optimized to improve the engine speed fluctuation during the warm-up process. If the normal mode has been entered, the warm-up mode will not be entered again to avoid the injection count from jumping back and forth. This is mainly to prevent the coolant temperature from not always rising after the start mode ends. There may be a situation where the temperature drops for a period of time and then continues to rise. The main reason is that the heat generated during engine startup not only heats the engine but also heats the vehicle's electric drive system (such as the power battery, motor, etc.), resulting in a drop in the coolant temperature. Then, when the engine's combustion power is stronger, the coolant temperature rises to near the target temperature. The optimized warm-up mode determination is as follows:

[0037] First, determine the warm-up coefficient r based on the engine combustion count Cnt CombustionCyl and the engine coolant temperature. WarmUp .

[0038] Among them, the method for obtaining the engine combustion count Cnt CombustionCyl is as follows:

[0039] Read the maximum value Cnt i and the minimum value Cnt Max in Cnt Min . Cnt i is the combustion count of the i-th cylinder, which refers to the number of fuel injection times of the i-th cylinder starting from when the engine speed is 0. When the engine speed is 0, the combustion count Cnt i is reset to 0. If the i-th cylinder is cut off from fuel injection, the combustion count Cnt i remains unchanged.

[0040] 1) If Cnt Max - Cnt Min < A, where A is taken as 5 in this embodiment. Among them N is the number of engine cylinders, and ri is a weighting coefficient. This indicates that the number of combustion cycles in each cylinder is similar, so the following averaging method can be used: ri is taken as...

[0041] 2) If Cnt Max -Cnt Min >B, in this example B is 20, indicating that the number of combustion cycles in each cylinder is not close, the engine experiences fuel cut-off, and the combustion cycles in each cylinder are inconsistent, so Cnt is read. Max Cylinder number x, Cnt Min If the cylinder number is y, then Cnt CombustionCyl Pick Other cylinders (other cylinders refer to those excluding Cnt) Min The minimum number of combustion cycles for the other cylinders corresponding to the cylinder number, where To obtain An integer that is not less than 0.

[0042] In the above calculations, the number of engine combustion cycles (Cnt) is... CombustionCyl Decrease is not allowed; if a decrease is detected, it will be controlled to remain constant. Therefore, the final engine combustion count, Cnt, is... CombustionCyl Only changes or additions are allowed.

[0043] Based on engine combustion frequency (Cnt) CombustionCyl Determine the warm-up coefficient r based on engine coolant temperature WarmUp The following is an example:

[0044]

[0045] The pattern is calculated and updated once every sampling period, which is 10ms in this example.

[0046] Then, the warm-up coefficient r WarmUp The engine is compared with a warm-up coefficient threshold to determine whether it is in warm-up mode. Specifically:

[0047] Once the start-up mode exit is detected, the warm-up coefficient r before the start-up mode exit is read. WarmUp Compare it with the warm-up coefficient threshold (0.1 in this example): 1) If it is not greater than 0, enter the normal mode instead of the warm-up mode; 2) If it is greater than 0, enter the warm-up mode.

[0048] If the system does not enter normal mode, in subsequent sampling periods, the real-time warm-up coefficient will be compared with the warm-up coefficient threshold: 1) If it is not greater than 0, the system will enter normal mode instead of warm-up mode; 2) If it is greater than 0, the system will remain in warm-up mode.

[0049] The cycle time will then be obtained using the method described above. Once normal mode is entered, it will not re-enter warm-up mode. Warm-up mode may only re-enter after the engine re-enters start mode (the specific method for obtaining this information is the same as above).

[0050] The above optimization of the warm-up mode is to ensure that engine speed fluctuations are optimized and that engine speed fluctuations are within ±20 rpm.

[0051] Warm-up mode design combustion injection frequency CNT Injection3Raw This part can be obtained from patent number 202010813483.2, entitled "Engine Fuel Injection Frequency Control Method, System, and Automobile". Specifically:

[0052] The table below shows the number of injections during warm-up mode:

[0053]

[0054] 4. Engine normal operating mode: All modes other than those mentioned above are considered normal engine operating modes. The number of combustion injections (CNT) is designed to improve emissions and engine combustion stability. Injection4Raw This part can be obtained from patent number 202010813483.2, entitled "Engine Fuel Injection Frequency Control Method, System and Automobile", specifically as follows:

[0055] The table showing the number of sprays in normal operating mode is as follows:

[0056]

[0057]

[0058] All four modes are based on engine speed n and fuel injection quantity m. fuelActive Cyl To determine the number of injections based on the operating conditions.

[0059] The priorities of the above modes decrease progressively. That is, if the start-up mode is satisfied, the control of the number of injections in the start-up mode is not considered, and the control of the number of injections in the start-up mode is activated. If the start-up mode is not satisfied, but the catalytic converter ignition mode is satisfied, the control of the catalytic converter ignition mode is activated regardless of whether the warm-up mode is satisfied. The control of other modes is determined according to their priorities.

[0060] The above determines the number of injections in four different modes, but the final number of injections (CNT) is... Injection The process will be optimized, specifically: When the combustion mode changes or remains unchanged, the final number of injections will be determined based on the injection frequency table for the four modes and the engine speed.

[0061] 1. When the combustion mode changes (a change in combustion mode means that the combustion mode in the previous sampling period is different from the combustion mode calculated in the current sampling period. The mode calculation and update are performed once every sampling period, and the sampling period is 10ms in this example), the number of injections is determined according to the injection count table for entering the mode (the method of obtaining the table is to take the nearest value on the coordinate axis, that is, take the injection count corresponding to the coordinate axis that is closer to it. If it is equally close to both sides of the coordinate axis, take the injection count corresponding to the larger coordinate axis). For example: if the starting mode is only entered in the current sampling period,

[0062] Assuming the engine speed n is 120 rpm and the fuel injection quantity m fuelActiveCyl If the value is 6mg, then according to the table lookup method, the engine speed n is taken as 200rpm, and the fuel injection quantity m is... fuelActiveCyl The number of sprays corresponding to 5mg is determined by looking up a table, which shows that the number of sprays is 1. (The method for obtaining the table is to take the nearest value on the coordinate axis, that is, take the number of sprays corresponding to the coordinate axis that is closest to it).

[0063] Assuming the engine speed n is 120 rpm and the fuel injection quantity m fuelActiveCyl If the value is 4mg, then according to the table lookup method, the engine speed n is taken as 200rpm, and the fuel injection quantity m is... fuelActiveCyl The number of sprays corresponding to 5mg is determined by looking up a table, which shows that the number of sprays is 1. (The method for obtaining the table is to take the nearest value on the coordinate axis, that is, take the number of sprays corresponding to the coordinate axis that is closest to it).

[0064] Assuming the engine speed n is 400 rpm and the fuel injection quantity m fuelActiveCyl If the value is 15mg, then according to the table lookup method, the engine speed n is taken as 400rpm, and the fuel injection quantity m is... fuelActiveCyl The number of sprays corresponding to 15mg is determined by looking up the table, which shows that the number of sprays is 2. (The method for obtaining the table is to take the nearest value on the coordinate axis, that is, take the number of sprays corresponding to the coordinate axis that is closest to it).

[0065] Assuming the engine speed n is 450 rpm and the fuel injection quantity m fuelActiveCyl If the value is 19mg, then according to the method above, take the engine speed n as 400rpm and the fuel injection quantity m. fuelActiveCyl The number of sprays corresponding to 20mg is determined by referring to a table, which shows that the number of sprays is 3. (The method for obtaining the table is to take the nearest value on the coordinate axis, that is, take the number of sprays corresponding to the coordinate axis that is closest to it).

[0066] Assuming the engine speed n is 900 rpm and the fuel injection quantity m fuelActiveCyl The value is 17.5mg. Therefore, according to the table lookup method, the engine speed n is taken as 1000rpm, and the fuel injection quantity m...fuelActiveCyl The number of sprays corresponding to 20mg is determined by referring to the table to be 3; (if the distance between the two coordinate axes is close, the number of sprays corresponding to the larger coordinate axis is taken).

[0067] When the combustion mode changes, the injection count from the table is immediately used to meet the control requirements of different modes. That is, when the combustion mode changes, the final injection count is the one obtained from the table using the above method.

[0068] At the same time, to avoid the occurrence of undesirable injection counts, the method of sampling closer to the coordinate axis is adopted (assuming that the number of injections changes from 3 to 1 due to the change in engine speed and fuel injection quantity. If linear interpolation is performed, it will pass through 2, but 2 is not the desired number of injections. Therefore, the method of sampling closer to the coordinate axis is adopted).

[0069] 2. When the combustion mode remains unchanged (meaning the combustion mode in the previous sampling period is the same as the combustion mode calculated in the current sampling period), based on the engine speed n and the fuel injection quantity m... fuelActiveCyl The injection frequency is determined from the injection frequency table for this mode (using the method of looking up the table with the closest coordinate axis to determine the injection frequency); based on the engine speed n' (obtained by subtracting the preset speed offset n1 from the engine speed n (in this example, the initial value is 100 rpm, and it is continuously updated, which will be explained in detail later) and the fuel injection quantity m fuelActiveCyl '(Based on fuel injection quantity m) fuelActiveCyl Subtracting the preset speed offset m1 (in this example, the initial value is 3mg, and it is continuously updated, which will be explained in detail later), the injection frequency table for this mode determines the second injection frequency (by looking up the table using the method of taking the closest coordinate axis). Based on the engine speed n' (obtained by adding the preset speed offset n1 (in this example, the initial value is 100rpm) to the engine speed n) and the fuel injection quantity m fuelActiveCyl '(Based on fuel injection quantity m) fuelActiveCyl Adding the preset rotational speed offset m1 (the initial value in this example is 3mg), the number of injections for this mode is determined by the table (the number of injections is determined by looking up the table based on the method of taking the closer coordinate axis).

[0070] 1) If injection times one, two, and three are all equal, then assuming the combustion mode remains unchanged, the engine speed n and fuel injection quantity m will be... fuelActiveCyl The final number of sprays is determined to be one of the original spray counts;

[0071] 2) If the number of injections (number 1, number 2, and number 3) are not equal, then when the combustion mode remains unchanged, the engine speed n and the fuel injection quantity m will be... fuelActiveCylThe final injection count remains unchanged, that is, it maintains the injection count obtained in the previous sampling period. The purpose of this is to avoid abnormal fluctuations in the engine or air-fuel ratio control caused by fluctuations in the injection count due to operating condition fluctuations (operating condition fluctuations refer to changes in engine speed and / or fuel injection quantity).

[0072] Due to issues such as carbon buildup in fuel injectors after prolonged use and aging of engine components, the preset speed offset n1 and preset speed offset m1 may deviate. Therefore, the preset speed offset n1 and preset speed offset m1 need to be self-learned and updated throughout the engine's lifespan to ensure control accuracy.

[0073] The next step will detail the self-learning update method for the preset speed offset n1 and preset speed offset m1. Self-learning updates can only be performed when the following conditions are met simultaneously:

[0074] The intake air temperature (the temperature of the gas entering the cylinder) fluctuates within ±3℃.

[0075] The throttle opening fluctuation range shall not exceed ±2.5%;

[0076] The vehicle speed fluctuation range is within ±2km / h;

[0077] The throttle opening fluctuation range shall not exceed ±2%;

[0078] The target intake pressure (target intake pressure entering the cylinder) fluctuation range shall not exceed ±3kPa;

[0079] The combustion mode remained unchanged;

[0080] No faults were detected;

[0081] The preset speed offset n1 was not updated in this driving cycle;

[0082] The preset speed offset m1 was not updated during this driving cycle;

[0083] Only after all the above conditions are met simultaneously and the duration exceeds T (3s in this example) is the update of the preset speed offset n1 (the preset speed offset n1 will be learned, updated, and stored according to two values, including n11 and n12, where n11 is used to calculate the first injection number and n12 is used to calculate the second injection number. By default, both n11 and n12 are 100 rpm and are continuously updated) and the preset speed offset m1 (the preset speed offset m1 will be learned, updated, and stored according to two values, including m11 and m12, where m11 is used to calculate the first injection number and m12 is used to calculate the second injection number. By default, both m11 and m12 are 3mg and are continuously updated) are allowed. Once the above is satisfied, the engine speed n and fuel injection quantity m are read under each operating condition (in this example, the method for determining the same self-learning operating condition is: the intake air temperature, throttle opening, target intake air pressure, vehicle speed, throttle opening, and combustion mode are the same. The definition of the same is based on the satisfaction of conditions 1-6 above) fuelActiveCyl The parameters include: injection frequency, target air-fuel ratio (target value, requested value of air-fuel ratio, and air-fuel ratio control based on this target value), actual air-fuel ratio (read by the front wide-range oxygen sensor), and target engine speed.

[0084] 1) If the fuel injection quantity m fuelActiveCyl If the fluctuation is small (fuel injection quantity fluctuation range within ±0.5mg), but the engine speed fluctuation is large (engine speed fluctuation range not within ±20rpm), and the injection frequency is not constant, then...

[0085] 1.1) If the speed closed-loop control is activated, the difference between the actual maximum speed and the target speed is taken as the positive deviation, that is, the positive deviation replaces n12 to calculate the second injection number, and the positive deviation is stored as the new n12; the difference between the target speed and the actual minimum speed is taken as the negative deviation, that is, the negative deviation replaces n11 to calculate the first injection number, and the negative deviation is stored as the new n11.

[0086] 1.2) If the engine speed closed-loop control is not activated, read the average engine speed, maximum engine speed, and minimum engine speed. Subtract the average engine speed from the maximum engine speed as the positive deviation, and subtract the minimum engine speed from the average engine speed as the negative deviation. Update the calculation of injection count one and injection count two using the same method as in 1.1), and update the storage of new n11 and n12.

[0087] 2) If the engine speed fluctuation is small (within ±20 rpm), but the fuel injection quantity m fuelActiveCyl If the fluctuations are large (the fuel injection quantity fluctuates within ±0.5mg) and the number of injections is not constant, then...

[0088] 2.1) If the air-fuel ratio is under closed-loop control activation (when the air-fuel ratio closed-loop control is activated, short-term fuel correction and long-term fuel correction control will be performed on the fuel control, where short-term fuel correction can be found in patent CN202111202932.0 "A method and control system for short-term fuel correction of an engine", and long-term fuel correction can be found in patent CN202010246641.0 "A self-learning method for long-term fuel correction of a gasoline engine"), then the difference between the actual maximum air-fuel ratio and the target speed is taken as the positive deviation, that is, the positive deviation replaces m12 to calculate the second injection number, and the positive deviation is stored as the new m12; the difference between the target speed and the actual minimum air-fuel ratio is taken as the negative deviation, that is, the negative deviation replaces m11 to calculate the first injection number, and the negative deviation is stored as the new m11;

[0089] 2.2) If the air-fuel ratio is not in closed-loop control activation, read the actual average air-fuel ratio, the actual maximum air-fuel ratio, and the actual minimum air-fuel ratio. Subtract the actual average air-fuel ratio from the actual maximum air-fuel ratio as the positive deviation, and subtract the actual minimum air-fuel ratio from the actual average air-fuel ratio as the negative deviation. Update the calculation of injection times one and injection times two, and update the storage of new m11 and m12, using the same method as in 2.1).

[0090] 3) If the engine speed fluctuation is small (within ±20 rpm), but the fuel injection quantity m fuelActiveCyl If the fluctuation is small (the fuel injection quantity fluctuation range is within ±0.5mg), the number of injections remains constant, and the actual air-fuel ratio fluctuation is small (within ±0.1 in this example), then n11, n12, m11, and m12 are taken as 0.95 times, 0.95 times, 0.98 times, and 0.98 times respectively from the previous storage and stored.

[0091] The values ​​n11, n12, m11, and m12 are updated at most once during each driving cycle. After being updated and stored, they are not used in the current driving cycle. When the next driving cycle is activated, the updated values ​​will be used to replace them.

[0092] During the transitional operating condition, i.e., after a change in operating condition (the definition of the same operating condition is explained earlier, and is the same as the self-learning operating condition), within a preset time T2 (0.5s in this example), 1) if the air-fuel ratio fluctuates too much (the air-fuel ratio change is not within ±0.1), the maximum value of m11 and m12 from these two operating conditions is immediately used to control the number of injections; otherwise, the minimum value from the two operating conditions is used to control the number of injections. 2) If the engine speed fluctuates too much (the engine speed fluctuation range is not within ±20rpm), the maximum value of n11 and n12 from these two operating conditions is immediately used to control the number of injections; otherwise, the minimum value from the two operating conditions is used to control the number of injections. This process continues until the operating condition changes again, and then the same method is used to determine which operating condition's n11, n12, m11, and m12 to select based on the air-fuel ratio and engine speed fluctuation. The adjustments to the preset engine speed offset n1 and preset engine speed offset m1 for the transitional operating condition are not stored; that is, they are re-evaluated and updated in the next driving cycle.

[0093] Example 2

[0094] An engine fuel injection frequency control system is provided for executing the engine fuel injection frequency control method in Example 1.

[0095] Example 3

[0096] An automobile includes the engine fuel injection frequency control system of Embodiment 2.

[0097] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

[0098] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for controlling the number of injections in a direct injection engine, characterized in that, The steps include the following: The engine operating conditions are divided into starting mode, catalytic converter ignition mode, warm-up mode, and normal operation mode. The number of combustion injections in each of the four modes is determined. Specifically, the number of combustion injections in starting mode is... The number of combustion injections in catalytic converter ignition mode is The number of combustion injections in warm-up mode is The number of combustion injections in normal operating mode is Establish a table of the number of sprays under four modes; The engine's operating condition is determined by the priority of the four modes; the priority of the four modes decreases from one to the next. In cases where the combustion mode changes or remains unchanged, the final number of combustion injections is determined based on the injection frequency table for the four modes and the engine speed. The engine warm-up mode is determined based on the priority of the four modes as follows: Based on engine combustion frequency Determine the warm-up coefficient based on engine coolant temperature ; Warm-up coefficient It is compared with the warm-up coefficient threshold to determine whether the engine is in warm-up mode; Based on engine combustion frequency Determine the warm-up coefficient based on engine coolant temperature The method is as follows: First, obtain the engine combustion count. : Read The maximum value in and minimum value ; The combustion count for the i-th cylinder refers to the number of fuel injections for the i-th cylinder, starting from engine speed 0. At engine speed 0, the combustion count is... Reset to 0; if the i-th cylinder is cut off from fuel, then the number of combustion cycles... Keep it from being updated; 1) When If A=5, then ,in N is the number of engine cylinders. As a weighting factor, when the number of combustion cycles in each cylinder is similar, then Pick ; 2) When B=20 indicates that the number of combustion cycles in each cylinder is not close, resulting in fuel cut-off in the engine and inconsistent combustion across cylinders; (Reading...) Cylinder number x, If the cylinder number is y, then Pick The minimum number of combustion cycles in other cylinders, where To obtain Integers not less than 0; In the above calculations, the number of engine combustion cycles... Decrease is not allowed; if a decrease is detected, it must be kept constant. Then based on the engine combustion frequency Determine the warm-up coefficient based on engine coolant temperature : The pattern is calculated and updated once every sampling period.

2. The method for controlling the number of injections in a direct injection engine according to claim 1, characterized in that: Warm-up coefficient The method for determining whether the engine is in warm-up mode is by comparing it with a warm-up coefficient threshold: Once the start-up mode exit is detected, the warm-up coefficient before the start-up mode exit is read. The value is compared with the warm-up coefficient threshold: 1) If it is not greater than 0, the system enters normal mode instead of warm-up mode; 2) If it is greater than 0, the system enters warm-up mode. If the normal mode is not entered, in subsequent sampling periods, the real-time warm-up coefficient is compared with the warm-up coefficient threshold: 1) If it is not greater than 0, the normal mode is entered instead of the warm-up mode; 2) If it is greater than 0, the warm-up mode is maintained. Once in normal mode, it will not enter warm-up mode again; it may only enter warm-up mode again after the engine enters start mode.

3. The method for controlling the number of injections in a direct injection engine according to claim 1, characterized in that: The table showing the number of injections in start-up mode is as follows: The table below shows the number of injections in catalytic converter ignition mode: The table below shows the number of injections during warm-up mode: The table showing the number of sprays in normal operating mode is as follows: 。 4. The method for controlling the number of injections in a direct injection engine according to claim 1, characterized in that: When the combustion mode changes or remains unchanged, the method for determining the final number of combustion injections based on the injection frequency table for the four modes and the engine speed is as follows: When the combustion mode changes, the number of injections is determined according to the injection frequency table of the entered mode. The table lookup method is as follows: take the nearest value on the coordinate axis, that is: take the injection frequency corresponding to the coordinate axis that is closer to it. If it is equally close to both sides of the coordinate axis, take the injection frequency corresponding to the larger coordinate axis. In addition, it is necessary to avoid the occurrence of undesirable injection frequencies. When undesirable injection frequencies occur, take the one closer to the coordinate axis. When the combustion mode remains unchanged, the injection frequency is determined according to the injection frequency table for that mode; based on engine speed... and fuel injection quantity The injection frequency table for this mode determines the number of injections, where engine speed is a factor. =Engine speed Subtract the preset speed offset n1, fuel injection quantity =Fuel ​​injection quantity Subtract the preset speed offset m1; based on the engine speed and fuel injection quantity The injection frequency table for this mode determines the number of injections three times, where engine speed is... =Based on engine speed (plus preset speed offset n1), fuel injection quantity =Fuel ​​injection quantity (plus the preset speed offset m1). 1) When injection times one, two, and three are equal, and the combustion mode remains unchanged, the engine speed at this time is... and fuel injection quantity The final number of sprays is determined to be one of the original spray counts; 2) When the number of injections (number 1, number 2, and number 3) are not equal, and the combustion mode remains unchanged, the engine speed at this time is... and fuel injection quantity The final number of sprays remains unchanged, that is, the number of sprays obtained in the previous sampling period is maintained.

5. The method for controlling the number of injections in a direct injection engine according to claim 4, characterized in that: Due to carbon buildup in fuel injectors after long-term use and aging of engine parts, the preset speed offset n1 and preset speed offset m1 will deviate. Therefore, the preset speed offset n1 and preset speed offset m1 need to be updated through self-learning throughout the entire engine life cycle. The preset rotational speed offset n1 is learned, updated, and stored according to two values: n11 and n12. n11 is used to calculate the first injection count, and n12 is used to calculate the second injection count. The preset rotational speed offset m1 is also learned, updated, and stored according to two values: m11 and m12. m11 is used to calculate the first injection count, and m12 is used to calculate the second injection count. n11, n12, m11, and m12 are continuously updated. The method for self-learning and updating the preset speed offset n1 and preset speed offset m1 is as follows: Determine whether the conditions for self-learning update are met; self-learning update can only be performed when all conditions are met simultaneously. Read engine speed under various operating conditions Fuel injection quantity Injection frequency, target air-fuel ratio, actual air-fuel ratio, target engine speed: 1) If the fuel injection quantity If the fluctuation is small, but the engine speed fluctuates greatly, and the number of injections is not constant, then... 1.1) If the speed closed-loop control is activated, the difference between the actual maximum speed and the target speed is taken as the positive deviation, that is, the positive deviation replaces n12 to calculate the second injection number, and the positive deviation is stored as the new n12; the difference between the target speed and the actual minimum speed is taken as the negative deviation, that is, the negative deviation replaces n11 to calculate the first injection number, and the negative deviation is stored as the new n11. 1.2) If the engine speed closed-loop control is not activated, read the average engine speed, the maximum engine speed, and the minimum engine speed; subtract the average engine speed from the maximum engine speed as the positive deviation, use the positive deviation to replace n12 to calculate the second injection number, and store the positive deviation as the new n12; subtract the minimum engine speed from the average engine speed as the negative deviation, use the negative deviation to replace n11 to calculate the first injection number, and store the negative deviation as the new n11. 2) If the engine speed fluctuation is small, but the fuel injection quantity is high If the fluctuations are large and the number of sprays is not constant, then 2.1) If the target air-fuel ratio is in closed-loop control activation, the difference between the actual maximum air-fuel ratio and the target engine speed is taken as a positive deviation. The positive deviation is used to replace m12 to calculate the second injection number, and the positive deviation is stored as the new m12. The difference between the target engine speed and the actual minimum air-fuel ratio is taken as a negative deviation. The negative deviation is used to replace m11 to calculate the first injection number, and the negative deviation is stored as the new m11. 2.2) If the target air-fuel ratio is not in closed-loop control activation, read the actual average air-fuel ratio, the actual maximum air-fuel ratio, and the actual minimum air-fuel ratio; subtract the actual average air-fuel ratio from the actual maximum air-fuel ratio as the positive deviation, use the positive deviation to replace m12 to calculate the second injection number, and store the positive deviation as the new m12; subtract the actual minimum air-fuel ratio from the actual average air-fuel ratio as the negative deviation, use the negative deviation to replace m11 to calculate the first injection number, and store the negative deviation as the new m11; 3) If the engine speed fluctuation is small, but the fuel injection quantity is high... If the fluctuation is small, the number of injections remains constant, and the actual air-fuel ratio fluctuates little, then n11, n12, m11, and m12 are taken as 0.95 times, 0.95 times, 0.98 times, and 0.98 times respectively from the previous storage and stored. The values ​​n11, n12, m11, and m12 are updated at most once in each driving cycle. After being updated and stored, they are not used in the current driving cycle. When the next driving cycle is activated, the updated values ​​will be used to replace them. During the transitional operating condition, i.e., within the preset time T2 after the operating condition changes, 1) if the air-fuel ratio fluctuates too much, the maximum value of m11 and m12 in these two operating conditions is immediately used to control the number of injections; otherwise, the minimum value in these two operating conditions is used to control the number of injections. 2) If the engine speed fluctuates too much, the maximum value of n11 and n12 in these two operating conditions is immediately used to control the number of injections; otherwise, the minimum value in these two operating conditions is used to control the number of injections. Until the operating condition changes again, the same method is used to determine which operating condition's n11, n12, m11, and m12 to select based on the air-fuel ratio and engine speed fluctuation. The adjustments to the preset engine speed offset n1 and preset engine speed offset m1 in the transitional operating condition are not stored; that is, they are re-judged and updated in the next driving cycle.

6. The method for controlling the number of injections in a direct injection engine according to claim 5, characterized in that: The self-learning update conditions for the preset speed offset n1 and preset speed offset m1 are: The temperature fluctuation range of the gas entering the cylinder is within ±3℃; The throttle opening fluctuation range shall not exceed ±2.5%; The vehicle speed fluctuation range is within ±2km / h; Throttle opening fluctuation range shall not exceed ±2%; The target intake pressure fluctuation range for the cylinder shall not exceed ±3kPa; The combustion mode remained unchanged; No faults were detected; The preset speed offset n1 was not updated in this driving cycle; The preset speed offset m1 was not updated during this driving cycle; Only after all the above conditions are met simultaneously and the duration exceeds T can the preset speed offset n1 and preset speed offset m1 be updated.

7. An engine fuel injection frequency control system, characterized in that, Used to perform the engine fuel injection number control method according to any one of claims 1 to 6.

8. A car, characterized in that, The engine fuel injection frequency control system as described in claim 7 above.

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