Spark ignition type engine control method and device

Abstract

The invention discloses a spark ignition type engine control method, relates to an internal combustion engine, and solves the technical problems of combustion efficiency reduction and single-cylinder misfire easily caused by non-uniform distribution of water in each cylinder in the case of an existing backward temperature compensation technology and a high EGR (Exhaust Gas Recirculation) rate. The method comprises the following steps: acquiring a first humidity value of an intake manifold in an engine, a second humidity value of each cylinder and a reference EGR opening value, calculating a correction coefficient according to the first humidity value, and calculating an EGR target opening value according to the reference EGR opening value and the correction coefficient; and a basic ignition angle is obtained, the humidity offset is calculated according to the second humidity value, the ignition angle compensation amount is calculated according to the humidity offset, and the basic ignition angle is compensated through the ignition angle compensation amount. The invention further discloses a spark-ignition engine control device. It is guaranteed that the engine operates at the knocking boundary for a long time, and efficient combustion is guaranteed.

Description

Technical Field

[0001] This invention relates to internal combustion engines, and more specifically, to a spark-ignition engine control method and apparatus. Background Technology

[0002] Low-carbon fuel engines, represented by natural gas (CNG / LNG) and methanol, as well as zero-carbon fuel engines such as hydrogen and ammonia, have become key technological pathways for decarbonization in the transportation sector due to their 50-100% lower carbon footprint compared to traditional gasoline. However, significant challenges remain in controlling humidity fluctuations (RH 30-95%) and combustion stability under high-boost conditions in these low-carbon and zero-carbon engines.

[0003] 1. Outdated humidity compensation technology: The existing solution uses a fixed humidity MAP for compensation, which cannot adapt to sudden changes in RH, resulting in an air-fuel ratio mismatch of ±1.2, leading to a 5-8% decrease in combustion efficiency.

[0004] 2. Uneven water distribution in cylinders at high EGR rates can easily cause misfires in a single cylinder: Low-carbon fuel engines, such as those using natural gas (CNG / LNG), methanol, and hydrogen, produce a large amount of water during combustion. When the exhaust gas EGR carries a large amount of water into each cylinder, it can easily lead to uneven water distribution and misfires in a particular cylinder. Currently, there is no effective solution. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a spark-ignition engine control method and device to address the shortcomings of the existing technology, and to solve the technical problems that the existing outdated temperature compensation technology and uneven water distribution in each cylinder at high EGR rates can easily lead to a decrease in combustion efficiency and cause misfire in a single cylinder.

[0006] The present invention discloses a spark-ignition engine control method, which involves obtaining a first humidity value of the intake manifold, a second humidity value of each cylinder, and a reference EGR opening value in the engine; calculating a correction coefficient based on the first humidity value; and calculating a target EGR opening value based on the reference EGR opening value and the correction coefficient.

[0007] Obtain the basic ignition angle, calculate the humidity offset based on the second humidity value, calculate the ignition angle compensation based on the humidity offset, and compensate the basic ignition angle using the ignition angle compensation.

[0008] Obtain the knock level signal value of each cylinder. When any knock level signal value is greater than a preset severe knock level threshold, subtract a preset attenuation value from the ignition angle compensation of all cylinders.

[0009] To further improve the calculation, the expression for the correction coefficient is as follows:

[0010] K_EGR=1-0.6%×(RH_actual1-50) / 10;

[0011] Where RH_actual1 is the first humidity value, and K_EGR is the correction factor;

[0012] The expression for calculating the EGR target opening value is as follows:

[0013] EGR final =MAP_EGR × K_EGR;

[0014] Among them, EGR final MAP_EGR is the target EGR opening value, and MAP_EGR is the baseline EGR opening value.

[0015] Furthermore, the expression for calculating the humidity offset is:

[0016] ΔRHx=RH_actual2-MAP_EGR×50%;

[0017] Among them, ΔRH x RH_actual2 is the humidity offset, and RH_actual2 is the second humidity value.

[0018] Furthermore, when the humidity offset is greater than zero, the ignition compensation is positive, requiring early ignition; when the humidity offset is less than zero, the ignition compensation is negative, requiring delayed ignition.

[0019] Furthermore, a safety limit range is set, and based on the ignition angle compensation amount and the safety limit range, it is determined whether to compensate the basic ignition angle.

[0020] When the ignition angle compensation amount is within the preset safety limit range, the basic ignition angle is added to the ignition angle compensation amount to obtain the final ignition angle;

[0021] When the ignition angle compensation amount is not within the preset safety limit range, the basic ignition angle is not compensated.

[0022] Furthermore, the expression for calculating the ignition angle compensation amount is as follows:

[0023] ΔΘx=0.15°CA / ΔRH×ΔRHx;

[0024] Where, ΔΘ x ΔRH represents the ignition angle compensation amount, and ΔRH is the percentage of humidity offset relative to the reference EGR opening value. x This represents the humidity offset.

[0025] Furthermore, the safety limit range is [-2°CA, +3°CA].

[0026] Furthermore, the severe knock level threshold is seven, and the attenuation value is 20% of the ignition compensation.

[0027] Furthermore, the processing priority of the knock level signal value is higher than that of humidity compensation.

[0028] A spark-ignition engine control device, comprising:

[0029] The first humidity sensor is installed in the intake manifold and is used to output the first humidity value signal;

[0030] Multiple second humidity sensors are installed in each intake manifold to output second humidity value signals;

[0031] The knock sensor is installed in the engine's combustion chamber and is used to output knock level signals for each cylinder;

[0032] The ECU collects the first humidity value signal, the second humidity value signal, and the knock level signal, and applies the above-mentioned spark-ignition engine control method to control engine ignition based on the first humidity value signal, the second humidity value signal, and the knock level signal.

[0033] Beneficial effects

[0034] The advantages of this invention are:

[0035] This invention compensates for humidity in the intake manifold and corrects ignition for different cylinders based on a first humidity value signal, a second humidity value signal, and a knock level signal under different humidity environments. It also uses high-frequency and high-vibration monitoring to prevent the engine from running into the knock zone after correction, while ensuring that the engine runs at the knock boundary for a long time, ensuring efficient combustion, thereby reducing gas consumption and improving the engine's power and economy. Attached Figure Description

[0036] Figure 1 This is a simplified structural diagram of the spark-ignition engine control device of the present invention;

[0037] Figure 2 This is a schematic diagram of the spark-ignition engine control device of the present invention;

[0038] Figure 3 This is a schematic diagram of the main logic of the spark-ignition engine control method of the present invention;

[0039] Figure 4 This is a detailed schematic diagram of the spark-ignition engine control logic of the present invention.

[0040] The components are: 1-muffler, 2-first humidity sensor, 3-intake manifold, 4-air filter, 5-intercooler, 6-air flow meter, 7-throttle valve, 8-EGR valve, 9-EGR cooler, 10-knock sensor, 11-combustion chamber, 12-intake manifold, 13-second humidity sensor, 14-cylinder block. Detailed Implementation

[0041] The present invention will be further described below with reference to embodiments, but this does not constitute any limitation on the present invention. Any limited modifications made by any person within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0042] See Figures 1-4 The present invention provides a spark-ignition engine control method, the method comprising,

[0043] Obtain the first humidity value of the intake manifold 3 in the engine and the second humidity value of each cylinder.

[0044] Obtain the baseline EGR opening value at the current engine speed and throttle opening. Query the baseline EGR opening value at the current engine speed and throttle opening from the pre-stored EGR pulse spectrum. This pulse spectrum data is calibrated with 50% RH as the baseline operating condition.

[0045] The correction factor is calculated based on the first humidity value, and the target EGR opening value is calculated based on the baseline EGR opening value and the correction factor.

[0046] The expression for calculating the correction factor is:

[0047] K_EGR=1-0.6%×(RH_actual1-50) / 10;

[0048] Where RH_actual1 is the first humidity value and K_EGR is the correction factor.

[0049] The expression for calculating the EGR target opening value is:

[0050] EGR final =MAP_EGR × K_EGR;

[0051] Among them, EGR final MAP_EGR is the target EGR opening value, and MAP_EGR is the baseline EGR opening value. Increased humidity reduces combustion stability, requiring a decrease in the EGR rate to prevent misfire. Decreased humidity, on the other hand, can cause knocking, necessitating an increase in the EGR rate to suppress it.

[0052] The sampling period for the second humidity value is 20ms.

[0053] The humidity offset is calculated based on the second humidity value to obtain the basic ignition angle. The ignition pulse spectrum (MAP_ign) is also calibrated at 50% RH. The ignition angle compensation is calculated based on the humidity offset. When the ignition angle compensation is within the preset safety limit range, the basic ignition angle and the ignition angle compensation are added together to obtain the final ignition angle.

[0054] The expression for calculating the humidity offset is:

[0055] ΔRHx=RH_actual2-MAP_EGR×50%;

[0056] Among them, ΔRH x RH_actual2 is the humidity offset, and RH_actual2 is the second humidity value.

[0057] When the humidity offset is greater than zero, it indicates high humidity, and the ignition compensation is positive, requiring ignition to be advanced. When the humidity offset is less than zero, it indicates low humidity, and the ignition compensation is negative, requiring ignition to be delayed.

[0058] The expression for calculating the ignition angle compensation is as follows:

[0059] ΔΘx=0.15°CA / ΔRH×ΔRHx;

[0060] Where, ΔΘ x ΔRH represents the ignition angle compensation amount, and ΔRH is the percentage of humidity offset relative to the reference EGR opening value. x This represents the humidity offset.

[0061] The safety limit range is [-2°CA, +3°CA]. The maximum value of the safety limit range, +3°CA, is intended to set the maximum retardation of a single cylinder to prevent deterioration of knocking. The minimum value of the safety limit range, -2°CA, is intended to set the maximum advance of a single cylinder to prevent a sudden drop in output torque, thus accommodating knock-sensitive characteristics. Furthermore, the safety limit range is set as an asymmetrical interval.

[0062] The knock level signal for each cylinder is acquired, with a value ranging from 0 to 10. When the knock level signal value exceeds a preset severe knock level threshold, a preset attenuation value is subtracted from the ignition angle compensation of all cylinders, and a humidity sensor re-inspection process is triggered. The first humidity sensor 2 and the second humidity sensor 13 are re-inspected to rule out sensor malfunction. The severe knock level threshold is seven, and the attenuation value is 20% of the ignition compensation. Knock handling has a higher priority than humidity compensation, reducing the compensation intensity of all cylinders and prioritizing mechanical safety to quickly exit the dangerous operating condition.

[0063] The regional control characteristics of EGR and ignition angle: EGR only responds to global humidity changes, while ignition angle only responds to inter-cylinder differences; the two are decoupled but coordinated. EGR correction does not participate in inter-cylinder balance, and inter-cylinder differences are adjusted only through ignition angle.

[0064] A spark-ignition engine control device, comprising:

[0065] The first humidity sensor 2 is installed in the intake manifold 3 and is used to output a first humidity value signal. The first humidity sensor 2 is installed before the EGR inlet point. The EGR inlet point is located in the manifold, so it is not possible to adjust the EGR of each cylinder, but only the ignition timing.

[0066] The first humidity sensor 2 is a capacitive relative humidity sensor (±2% RH accuracy). The signal transmission of the first humidity sensor 2 is a 0-5V analog output signal, corresponding to 10%-95% RH; the first humidity sensor 2 has a 5Hz refresh rate (updated every 200ms). The function of the first humidity sensor 2 is to provide an overall intake air humidity reference for the engine, used to calculate the EGR base opening and global ignition angle.

[0067] Multiple second humidity sensors 13 are installed in each intake manifold 12 to output second humidity value signals. The second humidity sensors 13 are positioned 15 cm away from the valve in each cylinder's intake manifold, and the sampling period of the second humidity sensors 13 is 20 ms (i.e., synchronous sampling every 120° of crankshaft rotation for all 6 cylinders). The key indicator of the second humidity sensors 13 is the detection of the absolute humidity difference between cylinders.

[0068] The knock sensor 10 is installed in the combustion chamber 11 of the engine and is used to output the knock level signal of each cylinder.

[0069] The ECU collects a first humidity value signal, a second humidity value signal, and a knock level signal, and applies the aforementioned spark-ignition engine control method to control engine ignition based on the first humidity value signal, the second humidity value signal, and the knock level signal.

[0070] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention, and these will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A method for controlling an ignition-type engine, characterized in that, The method includes obtaining a first humidity value of the intake manifold (3) in the engine, a second humidity value of each cylinder block (14) and a reference EGR opening value, calculating a correction coefficient based on the first humidity value, and calculating the target EGR opening value based on the reference EGR opening value and the correction coefficient. Obtain the basic ignition angle, calculate the humidity offset based on the second humidity value, calculate the ignition angle compensation based on the humidity offset, and compensate the basic ignition angle using the ignition angle compensation. Obtain the knock level signal value of each cylinder. When any knock level signal value is greater than a preset severe knock level threshold, subtract a preset attenuation value from the ignition angle compensation of all cylinders.

2. The spark-ignition engine control method according to claim 1, characterized in that, The expression for calculating the correction coefficient is as follows: K_EGR=1-0.6%×(RH_actual1-50) / 10; Where RH_actual1 is the first humidity value, and K_EGR is the correction factor; The expression for calculating the EGR target opening value is as follows: EGR final =MAP_EGR×K_EGR; Among them, EGR final MAP_EGR is the target EGR opening value, and MAP_EGR is the baseline EGR opening value.

3. The spark-ignition engine control method according to claim 1, characterized in that, The expression for calculating the humidity offset is: ΔRHx=RH_actual2-MAP_EGR×50%; Among them, ΔRH x RH_actual2 is the humidity offset, and RH_actual2 is the second humidity value.

4. The spark-ignition engine control method according to claim 1, characterized in that, When the humidity offset is greater than zero, the ignition compensation is positive, and ignition needs to be advanced. When the humidity offset is less than zero, the ignition compensation is negative, and ignition needs to be delayed.

5. The spark-ignition engine control method according to claim 1, characterized in that, Set a safety limit range, and determine whether to compensate the basic ignition angle based on the ignition angle compensation amount and the safety limit range. When the ignition angle compensation amount is within the preset safety limit range, the basic ignition angle is added to the ignition angle compensation amount to obtain the final ignition angle; When the ignition angle compensation amount is not within the preset safety limit range, the basic ignition angle is not compensated.

6. The spark-ignition engine control method according to claim 1, characterized in that, The expression for calculating the ignition angle compensation is: ΔΘx=0.15°CA / ΔRH×ΔRHx; Where, ΔΘ x ΔRH represents the ignition angle compensation amount, and ΔRH is the percentage of humidity offset relative to the reference EGR opening value. x This represents the humidity offset.

7. The spark-ignition engine control method according to claim 1, characterized in that, The safety limit range is [-2°CA, +3°CA].

8. The spark-ignition engine control method according to claim 1, characterized in that, The threshold for severe knocking level is seven, and the attenuation value is 20% of the ignition compensation.

9. The spark-ignition engine control method according to claim 1, characterized in that, The processing priority of the knock level signal value is higher than that of humidity compensation.

10. A spark-ignition engine control device, characterized in that, It includes: The first humidity sensor (2) is installed in the intake manifold (3) and is used to output the first humidity value signal; Multiple second humidity sensors (13) are installed in each intake manifold (12) to output second humidity value signals; A knock sensor (10) is installed in the combustion chamber (11) of the engine to output knock level signals for each cylinder; The ECU collects the first humidity value signal, the second humidity value signal, and the knock level signal, and applies the spark-ignition engine control method according to any one of claims 1-9 to control engine ignition based on the first humidity value signal, the second humidity value signal, and the knock level signal.

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