A combustion optimization control system and method for dual fuel micro-jet engines

Abstract

The application discloses a kind of combustion optimization control system and method for dual-fuel micro-injection engine, it is related to dual-fuel engine technical field, including working condition monitoring module, pilot oil compensation control module and fuel execution module, the pilot oil compensation control module is used for based on real-time working condition dynamic correction pilot oil injection parameter, the pilot oil compensation control module includes: injection parameter prediction unit, compensation amount calculation unit and injection correction unit.The application is installed with pilot oil compensation control module, adopts support vector machine model to predict reference parameter and dynamically compensate adaptive controller combination, realize millisecond level pilot oil injection correction, in fuel-gas mode switching process, combustion phase offset amount is controlled within ±0.8°CA, and speed fluctuation rate is reduced to below 5%, effectively eliminates torque mutation and the risk of flameout.

Description

Technical Field

[0001] This invention relates to the field of dual-fuel engine technology, specifically to a combustion optimization control system and method for a dual-fuel micro-injection engine. Background Technology

[0002] Dual-fuel micro-injection engines, as an important development direction of clean power technology, can significantly reduce nitrogen oxide and particulate matter emissions by using natural gas as the main fuel and a small amount of diesel for ignition. Existing combustion optimization control systems generally rely on fixed parameter mapping tables to control the ignition fuel injection process, which can maintain combustion stability under steady-state conditions. However, when the engine switches between fuel and gas modes, factors such as sudden changes in intake airflow velocity, variations in in-cylinder turbulence intensity, and residual exhaust gas fluctuations make it difficult for traditional open-loop control strategies to match dynamic operating conditions in real time, leading to mismatches between the ignition fuel injection quantity and timing. Experiments show that when such deviations exceed ±0.1 mg / cyc or ±0.5°CA, they will cause combustion phase shifts exceeding 3°CA, resulting in a sharp increase in engine speed fluctuations exceeding 15% or even combustion interruption, severely restricting the engineering application of dual-fuel technology.

[0003] Although some studies have attempted to introduce cylinder pressure feedback control in recent years, due to the strong nonlinear characteristics of the combustion process and the transmission delay of sensor signals, the response time of conventional PID control algorithms in the transient process of mode switching is still greater than 20ms, which cannot effectively suppress millisecond-level speed changes. Therefore, it is urgent to develop a real-time dynamic compensation mechanism with operating condition adaptive capability to overcome the technical bottleneck of mode switching instability.

[0004] Patent CN105971746B discloses a control system for a marine medium-speed micro-injection ignition dual-fuel engine. The patent realizes multiple injection control and stopping the injection mode of a certain channel; it uses the same control unit to realize the fuel supply control of the engine, which facilitates the synchronous and precise control of the fuel mode switching process, realizes the smooth transition of the engine, and optimizes the operating parameters of the dual-fuel engine.

[0005] The aforementioned patent comprises an engine operation monitoring unit, a safety protection unit, a fuel injection and speed control unit, and a parameter modification unit installed in a control box. Each unit is connected via a redundant CAN bus to enable data exchange and logical parameter modification. It also interacts with a human-machine interface via a Modbus bus to display parameters. This system can perform multiple injection controls and stop injection modes for a specific channel. Using a single control unit for engine fuel supply control facilitates synchronous and precise control during fuel mode switching, ensuring a smooth engine transition and optimizing dual-fuel engine operating parameters. However, the patent still has shortcomings in adaptive real-time dynamic compensation.

[0006] Therefore, this application proposes a combustion optimization control system and method for a dual-fuel micro-injection engine that is capable of adaptive real-time dynamic compensation. Summary of the Invention

[0007] The purpose of this invention is to provide a combustion optimization control system and method for a dual-fuel micro-injection engine to solve the technical problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a combustion optimization control system for a dual-fuel micro-injection engine, comprising an operating condition monitoring module, a pilot fuel compensation control module, and a fuel execution module, wherein the pilot fuel compensation control module is used to dynamically correct the pilot fuel injection parameters based on real-time operating conditions;

[0009] The pilot fuel compensation control module includes: an injection parameter prediction unit, a compensation amount calculation unit, and an injection correction unit;

[0010] The injection parameter prediction unit is equipped with an offline-trained support vector machine model and an online self-learning algorithm, and outputs the reference value of the ignition fuel quantity and the reference value of the injection timing.

[0011] The compensation calculation unit integrates an adaptive controller based on Lyapunov stability, which uses the angular acceleration deviation fed back by the crankshaft position sensor and the combustion phase offset fed back by the in-cylinder pressure sensor to calculate the pilot fuel quantity compensation coefficient and injection timing compensation amount.

[0012] The injection correction unit incorporates a microsecond-level time window correction algorithm, which calculates the compensation coefficient and compensation amount output by the compensation amount calculation unit, and performs real-time superposition correction on the baseline value output by the injection parameter prediction unit.

[0013] Preferably, the operating condition monitoring module is connected to the pilot fuel compensation control module via a high-speed CAN bus to collect engine operating status data;

[0014] The operating condition monitoring module includes: a crankshaft position sensing unit, an in-cylinder pressure sensing unit, and an air-fuel ratio detection unit;

[0015] It integrates a magnetoelectric pulse generator and a digital signal processor to output crankshaft angle signals and speed fluctuation characteristics in real time.

[0016] The cylinder pressure sensing unit integrates a piezoelectric force-sensitive element and a charge amplification circuit, and outputs cylinder pressure change rate data in real time through the cylinder head mounting hole;

[0017] The air-fuel ratio detection unit uses a wide-range oxygen sensor, which is located at the front of the exhaust pipe to detect the measured value of the excess air coefficient.

[0018] Preferably, the fuel injection module and the pilot fuel compensation control module are connected via the PWM signal line of the electronic control unit (ECU) for accurately executing fuel injection commands;

[0019] The fuel execution module includes: a pilot fuel injection unit, a fuel gas injection unit, and a drive circuit unit;

[0020] The pilot fuel injection unit uses a piezoelectric crystal micro-injector with a response time of ≤0.1ms, and performs micro-fuel injection based on the corrected pilot fuel quantity reference value;

[0021] The gas injection unit is equipped with a high-speed electromagnetic natural gas injection valve, which controls the natural gas injection pulse width based on commands from the electronic control unit (ECU).

[0022] The drive circuit unit integrates an H-bridge drive chip and an overcurrent protection circuit, converting the PWM signal into the injection valve drive current.

[0023] Preferably, the system also includes a combustion stability assessment module, which is connected to the ignition fuel compensation control module via a high-speed CAN bus to determine the combustion instability state in real time and trigger the compensation mechanism.

[0024] The combustion stability assessment module includes: an instability feature extraction unit, a mode switching decision unit, and a historical data storage unit;

[0025] The instability feature extraction unit integrates a fast Fourier transform hardware accelerator and calculates the pressure oscillation energy value in the 0.5-5kHz frequency band based on the output signal of the in-cylinder pressure sensing unit.

[0026] The mode switching decision unit integrates a dual threshold comparator circuit, which outputs an activation signal when the speed fluctuation characteristic value is greater than 250 rpm or the pressure oscillation energy value is greater than 200 J / deg.

[0027] The historical data storage unit uses FRAM non-volatile memory to record the compensation parameters and results of each mode switching process.

[0028] Preferably, the combustion stability assessment module further includes an online calibration interface;

[0029] The online calibration interface includes: a calibration parameter input port and a self-learning feedback port;

[0030] The calibration parameter input port supports the RS485 communication protocol and can receive the speed fluctuation threshold and pressure oscillation energy threshold input from external calibration equipment.

[0031] The self-learning feedback port transmits the compensation effect data from the historical data storage unit back to the support vector machine model of the fuel oil compensation control module.

[0032] Preferably, the system is also designed with a fault-tolerant module, which is connected to the pilot fuel compensation control module via an SPI bus to ensure the safety of the injection process;

[0033] The fault-tolerant module includes: a signal redundancy verification unit, an injection safety latch unit, and a fault code generation unit;

[0034] The signal redundancy verification unit is equipped with a phase difference detection circuit and a window comparator to compare the phase difference between the pulse signals of the crankshaft and camshaft position sensors. When the deviation is greater than 0.5°CA, an abnormality flag is triggered.

[0035] The injection safety latch unit integrates a numerical comparator and a parameter switcher. When the pilot fuel quantity compensation coefficient is greater than 15%, it switches to the preset fixed injection parameters.

[0036] The fault code generation unit is configured with a diagnostic protocol stack and a message generator to send fault codes associated with historical data indexes to the vehicle controller.

[0037] Preferably, the adaptive controller of the compensation calculation unit includes:

[0038] The phase offset input circuit is connected to the output terminal of the charge amplifier of the in-cylinder pressure sensor to receive the combustion phase offset voltage signal.

[0039] An angular acceleration conversion circuit is connected to the digital output interface of the crankshaft position sensing unit, converting the crankshaft pulse signal into a digital quantity of angular acceleration.

[0040] The gain parameter generator uses FPGA programmable logic devices to generate time-varying gain parameters based on the rate of change of excess air coefficient, the characteristic value of speed fluctuation, and angular acceleration.

[0041] The compensation quantity calculator integrates multiplier and adder circuits, and outputs digital signals of ignition fuel quantity compensation coefficient and injection timing compensation quantity.

[0042] Preferably, the gain parameter generator performs the following operations:

[0043] (1) The simulated signal of the excess air coefficient change rate of the air-fuel ratio detection unit is acquired by a 12-bit ADC;

[0044] (2) Read the digital value of the speed fluctuation characteristic from the SPI interface of the crankshaft position sensing unit;

[0045] (3) Receive the second derivative value of crankshaft angular acceleration output by the angular acceleration conversion circuit;

[0046] (4) Perform time-varying gain parameter calculation in the FPGA programmable logic device:

[0047]

[0048] Where: α, β, and γ are calibration constants, determined through bench calibration tests; dλ / dt is the rate of change of the excess air coefficient; Δn is the characteristic value of the speed fluctuation; d 2 θ / dt 2 K is the crankshaft angular acceleration. p K is the proportional gain parameter. i K is the integral gain parameter. d This is the differential gain parameter;

[0049] Preferably, the method includes the following steps:

[0050] S1. System initialization configuration: The operator burns the support vector machine model parameters and gain coefficients into the FRAM memory through an external calibration device;

[0051] S2, Sensor Calibration Start: Use a dedicated calibration tool to perform zero-point drift correction on the in-cylinder pressure sensor;

[0052] S3, Mode Switching Activation: The operator triggers a mode switching command from fuel oil to natural gas on the control panel;

[0053] S4. Compensation Result Recording: Manually read the compensation effect report from the historical data storage unit and back it up to an external device.

[0054] Preferably, the method further includes the following steps:

[0055] S11. The operator connects the USB interface of the calibration device to the RS485 port of the online calibration interface, selects the pre-stored calibration constant file through the calibration software interface, and performs the burning operation.

[0056] S21. Connect the output terminal of the charge amplifier of the in-cylinder pressure sensor to the analog input channel of the calibration tool. The operator adjusts the zero-point potentiometer to an error of <±0.5% according to the offset displayed by the calibration tool.

[0057] S31. In the operation interface of the engine control unit (ECU), select the "Dual Fuel Switch" button. When the speed fluctuation displayed on the instrument panel is >250 rpm, manually confirm the activation of pilot fuel compensation.

[0058] S41. Connect to the host computer via the data export interface of the FRAM memory. The operator executes the data reading command and saves the compensation parameter log file.

[0059] Compared with the prior art, the beneficial effects of the present invention are:

[0060] 1. This invention, by installing a pilot fuel compensation control module, combines the prediction of reference parameters using a support vector machine model with dynamic compensation by an adaptive controller to achieve millisecond-level pilot fuel injection correction. During the switching process between fuel and gas modes, the combustion phase offset is controlled within ±0.8°CA, and the speed fluctuation rate is reduced to below 5%, effectively eliminating torque mutation and stall risk.

[0061] 2. This invention integrates a multi-source data synchronous acquisition system with a working condition monitoring module, a magnetoelectric encoder, a piezoelectric ceramic sensor, and a wide-range oxygen sensor, and outputs real-time measured values ​​of speed fluctuation characteristics, cylinder pressure change rate, and excess air coefficient, providing a high-precision input reference for dynamic compensation;

[0062] 3. This invention uses a combustion stability assessment module to calculate the pressure oscillation energy value in real time based on a fast Fourier transform hardware accelerator, and combines it with a dual threshold comparator circuit to predict instability. When the speed fluctuation is >250 rpm or the pressure oscillation energy is >200 J / deg, a compensation mechanism is triggered within 3ms to suppress more than 85% of the instability risk in advance.

[0063] 4. This invention, by installing a fault-tolerant module and using a phase difference detection circuit to verify the consistency of crankshaft and camshaft signals, and cooperating with a numerical comparator to monitor the compensation coefficient in real time, immediately switches to preset safety parameters and generates a diagnostic code when the fuel quantity compensation coefficient is >15% or the phase deviation is >0.5°CA, thereby reducing the mis-injection failure rate from the industry average of 5% to below 0.1%. Attached Figure Description

[0064] Figure 1 This is a schematic diagram of the workflow of the present invention. Detailed Implementation

[0065] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0066] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0067] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral 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 a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0068] Please see Figure 1 One embodiment of this invention provides a combustion optimization control system for a dual-fuel micro-injection engine. When the engine switches from fuel mode to gas mode, the crankshaft position sensor of the operating condition monitoring module collects the speed fluctuation characteristic value in real time, the cylinder pressure sensor synchronously outputs the cylinder pressure change rate data, and the wide-range oxygen sensor detects the measured value of the excess air coefficient in the front section of the exhaust pipe. The above data is transmitted to the pilot fuel compensation control module via a high-speed CAN bus.

[0069] Inside the pilot fuel compensation control module, the injection parameter prediction unit calls an offline-trained support vector machine model, taking the received speed fluctuation feature values, cylinder pressure change rate, and measured values ​​of excess air coefficient as inputs, and outputs the pilot fuel quantity reference value and injection timing reference value. Simultaneously, the compensation calculation unit starts an adaptive controller based on Lyapunov stability, combining the angular acceleration deviation fed back by the crankshaft position sensor and the combustion phase offset fed back by the in-cylinder pressure sensor to calculate the pilot fuel quantity compensation coefficient and injection timing compensation amount. The injection correction unit activates a microsecond-level time window correction algorithm, superimposing the compensation coefficient and compensation amount output by the compensation calculation unit onto the reference value within a 50μs time window to generate the final corrected pilot fuel injection parameters.

[0070] Furthermore, after receiving the mode switching command, the engine control unit (ECU) continuously monitors the crankshaft angle signal using the magnetoelectric encoder of the operating condition monitoring module. When the detected speed fluctuation characteristic value exceeds the preset threshold, the piezoelectric ceramic sensor immediately acquires the current cylinder pressure change rate data, and the wide-range oxygen sensor simultaneously locks the measured value of the excess air coefficient. The support vector machine model maps the pilot fuel quantity reference value to 0.85 mg / cyc and the injection timing reference value to -12.5°CA based on historical training data. Simultaneously, the adaptive controller calculates the pilot fuel quantity compensation coefficient +8% and the injection timing compensation amount +0.6°CA based on the real-time angular acceleration deviation of 0.3 rad / s² and the combustion phase offset of 2.2°CA. The injection correction unit performs the superposition calculation of the reference value and the compensation amount within a microsecond time window using a hardware adder, and outputs the corrected pilot fuel injection parameters to the fuel execution module.

[0071] Please see Figure 1 This invention provides an embodiment of a combustion optimization control system for a dual-fuel micro-injection engine. The crankshaft position sensing unit of the operating condition monitoring module captures flywheel gear pulse signals via a magnetoelectric encoder. A digital signal processor converts these signals into digital values ​​of crankshaft angle and speed fluctuation characteristics. The piezoelectric ceramic sensor of the cylinder pressure sensing unit converts mechanical vibrations at the cylinder head bolt holes into charge signals, which are then amplified by a charge amplifier circuit to output an analog value of the cylinder pressure change rate. The wide-range oxygen sensor of the air-fuel ratio detection unit detects the exhaust oxygen concentration and outputs the measured value of the excess air coefficient via a calibration curve. All of the above data is transmitted to the pilot fuel compensation control module via a high-speed CAN bus.

[0072] The fuel execution module receives the corrected pilot fuel injection parameters: the piezoelectric crystal micro-injector of the pilot fuel injection unit opens the needle valve within 0.1ms and injects a small amount of diesel fuel at a rate of 0.918mg / cyc; the high-speed electromagnetic natural gas injection valve of the gas injection unit opens with a 5.2ms pulse width based on ECU instructions and injects the main fuel, natural gas; the H-bridge drive chip of the drive circuit unit converts the PWM signal into a 12V / 2A drive current, and the overcurrent protection circuit monitors the risk of current exceeding the limit in real time;

[0073] Furthermore, when the engine enters the transient operating condition of mode switching, the digital signal processor of the crankshaft position sensing unit collects flywheel tooth pulses at a resolution of 0.1°CA. When the rate of change of adjacent pulse intervals exceeds 3%, a speed fluctuation characteristic value of 252rpm is generated. The charge amplifier of the cylinder pressure sensing unit amplifies the 200pC charge signal output by the piezoelectric ceramic sensor into ±5V analog voltage, which is then converted into a digital quantity of cylinder pressure change rate of -0.8MPa / °CA by the ADC. The wide-range oxygen sensor calculates the exhaust oxygen concentration through the Nernst equation and outputs the measured value of excess air coefficient of 1.05. The drive circuit unit of the fuel execution module analyzes the PWM duty cycle signal sent by the fuel compensation control module, and the H-bridge drive chip outputs a 12V voltage to drive the piezoelectric crystal micro-injector, which opens for 87μs at the crankshaft angle position of -11.9°CA to achieve 0.918mg / cyc injection. Simultaneously, the high-speed electromagnetic natural gas injection valve is opened for 5.2ms to complete the main gas injection.

[0074] Please see Figure 1 The present invention provides an embodiment of a combustion optimization control system for a dual-fuel micro-injection engine. The instability feature extraction unit of the combustion stability evaluation module receives cylinder pressure change rate data output by the cylinder pressure sensing unit. It performs spectrum analysis on the 0.5-5kHz frequency band signal through an integrated fast Fourier transform hardware accelerator to calculate the pressure oscillation energy value. The mode switching decision unit compares the real-time speed fluctuation feature value and the pressure oscillation energy value with a preset threshold. When any parameter exceeds the limit, it sends an activation signal to the pilot fuel compensation control module through the high-speed CAN bus. The historical data storage unit uses an FRAM memory to record the current compensation parameters and combustion phase results.

[0075] The calibration parameter input port of the online calibration interface receives the speed fluctuation threshold correction value sent by the external calibration device through the RS485 communication protocol, such as adjusting it from 250rpm to 230rpm; the self-learning feedback port sends the compensated combustion phase offset recorded in the historical data storage unit, such as -0.7°CA, back to the support vector machine model to trigger the online self-learning algorithm to update the model weights.

[0076] Furthermore, during engine mode switching, the fast Fourier transform hardware accelerator of the instability feature extraction unit captures cylinder pressure change rate data at a sampling rate of 100kHz. After 1024-point FFT operation, the energy peak of 185J / deg at a frequency of 4.2kHz is extracted. The dual threshold comparator circuit of the mode switching decision unit synchronously detects the speed fluctuation feature value of 268rpm, which exceeds the 250rpm threshold. It immediately outputs a high-level activation signal to the pilot fuel compensation control module. The historical data storage unit writes the current pilot fuel quantity compensation coefficient +8%, injection timing compensation amount +0.6°CA, and the compensation combustion phase offset amount -0.7°CA into the FRAM storage area. The operator connects to the RS485 port through an external calibration device to adjust the speed fluctuation threshold from 250rpm to 230rpm. The self-learning feedback port automatically uploads the current compensation data packet to the support vector machine model. The model updates the speed weight coefficient from 0.35 to 0.41 through an incremental learning algorithm.

[0077] Please see Figure 1 This invention provides an embodiment of a combustion optimization control system for a dual-fuel micro-injection engine. The signal redundancy verification unit of the fault-tolerant module compares the pulse rise time difference between the crankshaft position sensor and the camshaft position sensor via a phase difference detection circuit. When a phase deviation > 0.5°CA is detected, an abnormal flag is triggered. The numerical comparator of the injection safety latch unit monitors the pilot fuel quantity compensation coefficient in real time. When the compensation coefficient > 15%, it switches to preset safety parameters: pilot fuel quantity 0.75 mg / cyc, injection timing -10°CA. The fault code generation unit generates a CAN message containing fault type codes such as P0300 and historical data indexes, with FRAM address 0x5A3, based on the diagnostic protocol stack and sends it to the vehicle controller.

[0078] Furthermore, during the engine mode switching phase, the window comparator of the signal redundancy verification unit continuously monitors the rise time difference of the crankshaft and camshaft sensor pulses. When the crankshaft sensor experiences a pulse delay of 0.8ms due to flywheel backlash, corresponding to a phase deviation of 0.6°CA, the window comparator outputs an over-limit signal to trigger an abnormal flag. Simultaneously, the injection safety latch unit detects that the pilot fuel quantity compensation coefficient has reached +18%, and the numerical comparator immediately outputs a switching command. The parameter switcher forcibly switches the injection parameters from the dynamic compensation value, 1.02mg / cyc, -13.2°CA, to the preset safety parameters, 0.75mg / cyc, -10°CA. The fault code generation unit calls the UDS diagnostic protocol stack to generate a CAN message containing fault code P0303, cylinder 3 misfire, and associated historical data storage address 0x5A3, which is sent to the vehicle controller at a baud rate of 500kbps.

[0079] Please see Figure 1One embodiment of the present invention provides a combustion optimization control system for a dual-fuel micro-injection engine. The phase offset input circuit of the compensation calculation unit receives the combustion phase offset voltage signal output by the charge amplifier of the in-cylinder pressure sensor, such as -1.2V corresponding to 3°CA; the angular acceleration conversion circuit analyzes the digital pulse signal from the crankshaft position sensing unit and calculates the crankshaft angular acceleration, such as -420 rad / s², through second-order differentiation. 2 The gain parameter generator uses an FPGA programmable logic device, based on the excess air coefficient change rate of 0.15s. -1 The characteristic value of rotational speed fluctuation at 240 rpm and the time-varying gain parameter generated by angular acceleration, K p =0.32, K i =0.08, K d =0.15; The compensation quantity calculator calculates K through the multiplier. p ·e(t), the integral and differential terms synthesized by the adder, and the final output is the pilot fuel quantity compensation coefficient +7.2% and the injection timing compensation amount +0.5°CA;

[0080] Furthermore, the charge amplifier of the in-cylinder pressure sensor outputs a combustion phase offset analog voltage of -1.2V. After calibration, corresponding to a 3° CA delay, the 12-bit ADC of the phase offset input circuit quantizes it into a digital value of 3072. The angular acceleration conversion circuit reads the 0.1° CA timestamp data from the SPI interface of the crankshaft position sensing unit and calculates the current angular acceleration of -420 rad / s using the second-order central difference method. 2 The FPGA of the gain parameter generator performs the following calculation: It acquires the excess air coefficient change rate of the air-fuel ratio detection unit at 0.15s. -1 The rotational speed fluctuation characteristic value was read as 240 rpm, and the second derivative of the angular acceleration was received as -1050 rad / s. 3 According to formula K p =0.0021 × 0.15 = 0.32, K i =0.00033×240=0.08, K d =0.00014×(-1050)=-0.15; The multiplier of the compensation quantity calculator calculates the proportional term 0.32×3°CA=0.96°CA, the integral term 0.08×∫3°CA dt=0.24°CA, and the differential term (-0.15)×(-420)=63. After being combined by the adder, the injection timing compensation quantity is +0.5°CA; the synchronous output pilot fuel quantity compensation coefficient is +7.2%;

[0081] The calibration constants α, β, and γ in the gain parameter generator were determined through bench calibration tests. The specific process was as follows: The engine was mounted on a dynamic dynamometer bench, and the crankshaft position sensor, cylinder pressure sensor, and wide-range oxygen sensor of the operating condition monitoring module were connected, and the emissions analyzer was connected simultaneously. The initial parameter set was input to the online calibration interface through the calibration equipment. First, under steady-state conditions of 1500 rpm and 25% load, the fuel mode was switched, and the α value was adjusted until the correlation coefficient between the excess air coefficient change rate and the combustion phase offset exceeded 0.95. Then, under transient conditions with a 10 rpm / s load step increase, the β value was adjusted so that the root mean square error between the speed fluctuation characteristic value and the pilot fuel quantity compensation coefficient was less than 3%. Finally, the γ value was optimized under the -10℃ low-temperature cold start condition to ensure that the angular acceleration closed-loop response delay was less than 2ms. Finally, α=0.0021, β=0.00033, and γ=0.00014 were determined and written into the non-volatile memory of the gain parameter generator.

[0082] Working principle: First, the operating condition monitoring module acquires the crankshaft angle signal on the flywheel side of the engine in real time through the magneto-electric encoder of the crankshaft position sensing unit and calculates the speed fluctuation characteristic value. The piezoelectric ceramic sensor of the cylinder pressure sensing unit synchronously detects the pressure vibration at the cylinder head bolt holes and outputs the cylinder pressure change rate data. The wide-range oxygen sensor of the air-fuel ratio detection unit measures the exhaust oxygen concentration in the front section of the exhaust pipe and converts it into the measured value of the excess air coefficient. The above parameters are transmitted to the pilot fuel compensation control module through the high-speed CAN bus.

[0083] Next, the injection parameter prediction unit of the pilot fuel compensation control module calls the offline trained support vector machine model, inputs the received speed fluctuation feature value, cylinder pressure change rate and excess air coefficient measured value into the model, and outputs the pilot fuel quantity reference value and injection timing reference value; the compensation amount calculation unit simultaneously starts the adaptive controller based on Lyapunov stability, combines the angular acceleration deviation fed back by the crankshaft position sensor and the combustion phase offset fed back by the cylinder pressure sensor, and calculates the pilot fuel quantity compensation coefficient and injection timing compensation amount; the injection correction unit activates the microsecond-level time window correction algorithm, superimposes the compensation amount onto the reference value within the preset time window, generates the corrected pilot fuel injection parameters and sends them to the fuel execution module through the PWM signal line of the electronic control unit (ECU);

[0084] Finally, the drive circuit unit of the fuel execution module converts the PWM signal into a drive current. The piezoelectric crystal micro-injector of the pilot fuel injection unit performs micro-fuel injection according to the corrected pilot fuel quantity reference value. The high-speed electromagnetic natural gas injection valve of the gas injection unit controls the natural gas injection pulse width based on ECU instructions. The combustion stability assessment module analyzes the cylinder pressure oscillation energy and speed fluctuation characteristics in real time. When an instability risk is detected, a compensation mechanism is triggered to update the support vector machine model. At the same time, the fault tolerance module verifies the signal consistency and monitors the over-limit behavior of the compensation coefficient to ensure a safe closed loop in the injection process.

[0085] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A combustion optimization control system for a dual-fuel micro-injection engine, characterized in that: It includes a working condition monitoring module, a pilot fuel compensation control module, and a fuel execution module. The pilot fuel compensation control module is used to dynamically correct the pilot fuel injection parameters based on real-time working conditions. The pilot fuel compensation control module includes: an injection parameter prediction unit, a compensation amount calculation unit, and an injection correction unit; The injection parameter prediction unit is equipped with an offline-trained support vector machine model and an online self-learning algorithm, and outputs the reference value of the ignition fuel quantity and the reference value of the injection timing. The compensation calculation unit integrates an adaptive controller based on Lyapunov stability, which uses the angular acceleration deviation fed back by the crankshaft position sensor and the combustion phase offset fed back by the in-cylinder pressure sensor to calculate the pilot fuel quantity compensation coefficient and injection timing compensation amount. The injection correction unit incorporates a microsecond-level time window correction algorithm, which calculates the compensation coefficient and compensation amount output by the compensation amount calculation unit, and performs real-time superposition correction on the baseline value output by the injection parameter prediction unit.

2. The combustion optimization control system for a dual-fuel micro-injection engine according to claim 1, characterized in that: The operating condition monitoring module and the pilot fuel compensation control module are connected via a high-speed CAN bus to collect engine operating status data; The operating condition monitoring module includes: a crankshaft position sensing unit, an in-cylinder pressure sensing unit, and an air-fuel ratio detection unit; It integrates a magnetoelectric pulse generator and a digital signal processor to output crankshaft angle signals and speed fluctuation characteristics in real time. The cylinder pressure sensing unit integrates a piezoelectric force-sensitive element and a charge amplification circuit, and outputs cylinder pressure change rate data in real time through the cylinder head mounting hole; The air-fuel ratio detection unit uses a wide-range oxygen sensor, which is located at the front of the exhaust pipe to detect the measured value of the excess air coefficient.

3. The combustion optimization control system for a dual-fuel micro-injection engine according to claim 1, characterized in that: The fuel injection module and the pilot fuel compensation control module are connected via the PWM signal line of the electronic control unit (ECU) to accurately execute fuel injection commands; The fuel execution module includes: a pilot fuel injection unit, a fuel gas injection unit, and a drive circuit unit; The pilot fuel injection unit uses a piezoelectric crystal micro-injector with a response time of ≤0.1ms, and performs micro-fuel injection based on the corrected pilot fuel quantity reference value; The gas injection unit is equipped with a high-speed electromagnetic natural gas injection valve, which controls the natural gas injection pulse width based on commands from the electronic control unit (ECU). The drive circuit unit integrates an H-bridge drive chip and an overcurrent protection circuit, converting the PWM signal into the injection valve drive current.

4. A combustion optimization control system for a dual-fuel micro-injection engine according to claim 1, characterized in that: The system is also designed with a combustion stability assessment module, which is connected to the ignition fuel compensation control module via a high-speed CAN bus to determine the combustion instability state in real time and trigger the compensation mechanism. The combustion stability assessment module includes: an instability feature extraction unit, a mode switching decision unit, and a historical data storage unit; The instability feature extraction unit integrates a fast Fourier transform hardware accelerator and calculates the pressure oscillation energy value in the 0.5-5kHz frequency band based on the output signal of the in-cylinder pressure sensing unit. The mode switching decision unit integrates a dual threshold comparator circuit, which outputs an activation signal when the speed fluctuation characteristic value is greater than 250 rpm or the pressure oscillation energy value is greater than 200 J / deg. The historical data storage unit uses FRAM non-volatile memory to record the compensation parameters and results of each mode switching process.

5. A combustion optimization control system for a dual-fuel micro-injection engine according to claim 4, characterized in that: The combustion stability assessment module also includes an online calibration interface; The online calibration interface includes: a calibration parameter input port and a self-learning feedback port; The calibration parameter input port supports the RS485 communication protocol and can receive the speed fluctuation threshold and pressure oscillation energy threshold input from external calibration equipment. The self-learning feedback port transmits the compensation effect data from the historical data storage unit back to the support vector machine model of the fuel oil compensation control module.

6. A combustion optimization control system for a dual-fuel micro-injection engine according to claim 1, characterized in that: The system is also designed with a fault-tolerant module, which is connected to the pilot fuel compensation control module via the SPI bus to ensure the safety of the injection process. The fault-tolerant module includes: a signal redundancy verification unit, an injection safety latch unit, and a fault code generation unit; The signal redundancy verification unit is equipped with a phase difference detection circuit and a window comparator to compare the phase difference between the pulse signals of the crankshaft and camshaft position sensors. When the deviation is greater than 0.5°CA, an abnormality flag is triggered. The injection safety latch unit integrates a numerical comparator and a parameter switcher. When the pilot fuel quantity compensation coefficient is greater than 15%, it switches to the preset fixed injection parameters. The fault code generation unit is configured with a diagnostic protocol stack and a message generator to send fault codes associated with historical data indexes to the vehicle controller.

7. A combustion optimization control system for a dual-fuel micro-injection engine according to claim 1, characterized in that: The adaptive controller of the compensation calculation unit includes: The phase offset input circuit is connected to the output terminal of the charge amplifier of the in-cylinder pressure sensor to receive the combustion phase offset voltage signal. An angular acceleration conversion circuit is connected to the digital output interface of the crankshaft position sensing unit, converting the crankshaft pulse signal into a digital quantity of angular acceleration. The gain parameter generator uses FPGA programmable logic devices to generate time-varying gain parameters based on the rate of change of excess air coefficient, the characteristic value of speed fluctuation, and angular acceleration. The compensation quantity calculator integrates multiplier and adder circuits, and outputs digital signals of ignition fuel quantity compensation coefficient and injection timing compensation quantity.

8. A combustion optimization control system for a dual-fuel micro-injection engine according to claim 7, characterized in that: The gain parameter generator performs the following operations: (1) The simulated signal of the excess air coefficient change rate of the air-fuel ratio detection unit is acquired by a 12-bit ADC; (2) Read the digital value of the speed fluctuation characteristic from the SPI interface of the crankshaft position sensing unit; (3) Receive the second derivative value of crankshaft angular acceleration output by the angular acceleration conversion circuit; (4) Perform time-varying gain parameter calculation in the FPGA programmable logic device: ； Where: α, β, and γ are calibration constants, determined through bench calibration tests; dλ / dt is the rate of change of the excess air coefficient; Δn is the characteristic value of the speed fluctuation; d 2 θ / dt 2 K is the crankshaft angular acceleration. p K is the proportional gain parameter. i K is the integral gain parameter. d This is the differential gain parameter.

9. A combustion optimization control method for a dual-fuel micro-injection engine, applicable to the system described in any one of claims 1-8, characterized in that: The method includes the following steps: S1. System initialization configuration: The operator burns the support vector machine model parameters and gain coefficients into the FRAM memory through an external calibration device; S2, Sensor Calibration Start: Use a dedicated calibration tool to perform zero-point drift correction on the in-cylinder pressure sensor; S3, Mode Switching Activation: The operator triggers a mode switching command from fuel oil to natural gas on the control panel; S4. Compensation Result Recording: Manually read the compensation effect report from the historical data storage unit and back it up to an external device.

10. The combustion optimization control method for a dual-fuel micro-injection engine according to claim 9, characterized in that: The method further includes the following steps: S11. The operator connects the USB interface of the calibration device to the RS485 port of the online calibration interface, selects the pre-stored calibration constant file through the calibration software interface, and performs the burning operation. S21. Connect the output terminal of the charge amplifier of the in-cylinder pressure sensor to the analog input channel of the calibration tool. The operator adjusts the zero-point potentiometer to an error of <±0.5% according to the offset displayed by the calibration tool. S31. In the operation interface of the engine control unit (ECU), select the "Dual Fuel Switch" button. When the speed fluctuation displayed on the instrument panel is >250 rpm, manually confirm the activation of pilot fuel compensation. S41. Connect to the host computer via the data export interface of the FRAM memory. The operator executes the data reading command and saves the compensation parameter log file.

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