Method and device for pre-controlling knocking and misfire of dual-fuel engine
By identifying engine operating conditions and switching combustion parameters through the ECU, the knocking and misfire problems of dual-fuel engines under changing operating conditions are solved, achieving stable and reliable engine operation.
Patent Information
- Application Number
- CN202511397283.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-28
- Publication Date
- 2025-11-18
AI Technical Summary
When operating conditions and loads change, dual-fuel engines may experience knocking and misfires due to uneven air-fuel mixture caused by turbocharger lag and fluctuations in intake flow, affecting the engine's reliability and stability.
The engine operating condition is identified by the ECU, and the substitution rate, injection advance angle and fuel rail pressure are controlled by switching between steady state and transient MAP to achieve flexible combustion and reduce the risk of knock and misfire.
To ensure the stability of the engine during the transition between transient and steady-state operating conditions, and to improve the engine's durability, reliability, and flexible combustion performance throughout its entire life cycle.
Smart Images
Figure CN120968936A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of dual-fuel engine technology, specifically relating to a method and device for pre-controlling knock and misfire in a dual-fuel engine. Background Technology
[0002] Methanol is a highly efficient, clean, and synthetic liquid oxygenated fuel. With the further development of renewable energy technologies, the production of green methanol using hydrogen generated from renewable energy sources and CO2 obtained through capture can significantly reduce the carbon emissions throughout the methanol's life cycle. Therefore, diesel / methanol combined combustion (DMCC) technology is widely used in compression ignition engines, improving their combustion and emission performance and possessing significant carbon reduction potential in the medium to long term. However, when operating conditions and loads change in engines using DMCC technology, the turbocharger's lag and fluctuations in intake airflow can lead to uneven mixing of the premixed methanol-fuel mixture entering the cylinder with the working fluid. This can result in locally overly rich mixtures causing detonation, exceeding design limits and compromising cylinder mechanical strength, thus compromising engine reliability. Furthermore, methanol has a cetane number (≈2) that is much lower than that of conventional diesel (>50), and a latent heat of vaporization (approximately 1,168 kJ / kg) that is significantly higher than that of diesel (approximately 250 kJ / kg). This leads to problems such as ignition difficulties or even misfires in engines using diesel / methanol combined combustion (DMCC) technology when operating conditions and loads change at a high substitution rate, which damages the reliability and stability of the engine. Summary of the Invention
[0003] The technical problem to be solved by the present invention is to provide a method and device for pre-controlling knock and misfire of a dual-fuel engine, which can actively pre-control the occurrence of misfire and knock in the transient process of the engine, and ensure flexible combustion and durable reliability throughout the entire life cycle of the dual-fuel engine.
[0004] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:
[0005] A method for preventing knocking and misfire in a dual-fuel engine includes: an ECU with a steady-state substitution rate MAP, a steady-state injection advance angle MAP, a steady-state fuel rail pressure MAP, a transient substitution rate MAP, a transient injection advance angle MAP, and a transient fuel rail pressure MAP; when the engine enters dual-fuel mode, engine operating parameters are collected, and transient and steady-state operating conditions are identified based on the operating parameters; the ECU selects the corresponding transient or steady-state substitution rate MAP, fuel injection advance angle MAP, and fuel rail pressure MAP based on the operating condition judgment result, and the substitution rate, injection advance angle, and fuel rail pressure output by the ECU are switched from the current MAP lookup value to the transient or steady-state MAP lookup value corresponding to the current engine operating parameters.
[0006] Furthermore, when the engine is operating in a transient state or a steady-state-to-transient state, the ECU employs steady-state-to-transient control, rapidly adjusting the substitution rate, injection advance angle, and fuel rail pressure to the corresponding transient MAP lookup values. When the engine is operating in a steady-state state or a transient-to-steady-state state, the ECU employs transient-to-steady-state control, slowly adjusting the substitution rate, injection advance angle, and fuel rail pressure to the corresponding steady-state MAP lookup values. Further, the steady-state-to-transient control and the transient-to-steady-state control involve linearizing the current substitution rate, injection advance angle, and fuel rail pressure using different rates of change to transition to the corresponding transient or steady-state MAP lookup values.
[0007] Furthermore, the steady-state to transient control and the transient to steady-state control are to linearize and transition the MAP lookup values of the current substitution rate, injection advance angle and fuel rail pressure to the corresponding transient or steady-state MAP lookup values according to different rates of change.
[0008] Furthermore, during the transition from steady-state to transient control, the rate of change of the substitution rate is 10% / s, the rate of change of the injection advance angle is 4°CA / s, and the rate of change of the fuel rail pressure is 20MPa / s; during the transition from transient to steady-state control, the rate of change of the substitution rate is 0.5% / s, the rate of change of the injection advance angle is 2°CA / s, and the rate of change of the fuel rail pressure is 5MPa / s.
[0009] Furthermore, the operating parameters include the actual engine speed, target speed, mode status, current intake air volume, and fault status; the actual speed is the value measured by the speed sensor; the target speed is the value measured by the throttle position sensor; the current intake air volume is the intake air flow rate after boosting detected by the sensor; when the engine enters dual-fuel mode, the mode status is 1; when the engine reports no fault, the fault status is 1.
[0010] Furthermore, when the deviation between the actual engine speed and the target engine speed is less than a first set value, the rate of change of engine speed ΔV / Δt within time Δt is less than a second set value, the deviation between the current intake air volume and the filtered intake air volume is less than a third set value, and no fault is reported, then it is determined that the engine is operating under steady-state conditions; the filtered intake air volume is the value after the ECU filters and de-jitters the value of the current intake air volume.
[0011] Furthermore, if one or more of the following conditions are met: the deviation between the actual engine speed and the target engine speed is greater than the first set value; the rate of change of engine speed ΔV / Δt within time Δt is greater than the second set value; or the deviation between the current intake air volume and the filtered intake air volume is greater than the third set value, then the engine is determined to be in transient operating condition or steady-state-to-transient operating condition.
[0012] A knock and misfire prevention device for a dual-fuel engine includes: an ECU and a dual-fuel mode switch electrically connected to the ECU, a boost air pressure sensor, an engine speed sensor, a throttle position sensor, a common rail fuel pressure sensor, a fuel injection pump, and an alcohol injector; the ECU is configured with a first setpoint, a second setpoint, a third setpoint, a steady-state substitution rate MAP, a steady-state injection advance angle MAP, a steady-state fuel rail pressure MAP, a transient substitution rate MAP, a transient injection advance angle MAP, and a transient fuel rail pressure MAP; the ECU receives the opening signal from the dual-fuel mode switch. After the start signal is received, the engine's steady-state and transient operating conditions are identified based on the deviation between the current engine speed and the target speed, the rate of change of engine speed, and the deviation between the current intake air volume and the filtered intake air volume. According to the switching direction between transient and steady state, the currently operating substitution rate value, injection advance angle value, and fuel rail pressure are linearized and controlled to transition to the corresponding transient or steady-state MAP lookup value using different change rates. The ECU transmits the real-time calculated substitution rate, injection advance angle, and fuel rail pressure to the injectors, alcohol injectors, and fuel metering unit to control the execution of alcohol injection quantity, fuel injection quantity, injection advance angle, and fuel rail pressure under different substitution rates.
[0013] Furthermore, the ECU includes: a transient / steady-state coordinator, used to collect and calculate the deviation between the current engine speed and the target speed, the rate of change of engine speed, and the deviation between the current intake air volume and the filtered intake air volume based on various sensor parameters; to identify and output the transient and steady-state operating conditions of the engine based on the comparison of the calculated values with set values; a hysteresis controller, which receives the operating condition status signal output by the transient / steady-state coordinator; and outputs the operating condition status signal as the final operating condition status signal when it is confirmed that the comparison result in the transient / steady-state coordinator is not caused by a sudden change due to interference; and a steady-state MAP selector, used to receive the operating condition status signal output by the hysteresis controller; and to retrieve and output the steady-state substitution rate MAP, steady-state injection advance angle MAP, and steady-state fuel rail pressure from the memory based on the signal. MAP output or no output; Transient MAP selector, used to receive the operating condition status signal output by the hysteresis controller, and retrieve and output transient substitution rate MAP, transient injection advance angle MAP, transient fuel rail pressure MAP from the memory according to the signal, or no output; Slope controller, used to receive the MAP output by the steady-state MAP selector or the transient MAP selector, and output the rate of change of substitution rate, injection advance angle and fuel rail pressure in the corresponding operating condition switching direction according to the MAP; Parameter arbitrator, used to receive the rate of change of substitution rate, injection advance angle and fuel rail pressure output by the slope controller, and calculate the current required substitution rate, injection advance angle and fuel rail pressure in combination with the substitution rate, injection advance angle and fuel rail pressure of the previous cycle, and output them to the injector, alcohol injector and fuel metering unit.
[0014] After adopting the above technical solution, the beneficial effects of the present invention are:
[0015] The dual-fuel engine knock and misfire prevention method and device disclosed in this invention identifies the transient and steady-state operating conditions of the engine in dual-fuel mode. Based on the steady-state and transient judgment results, it selects the corresponding transient or steady-state substitution rate MAP, fuel injection advance angle MAP, and fuel rail pressure MAP, switching them from the current MAP lookup table value to the corresponding transient or steady-state MAP lookup table value. Through actuators, namely fuel injectors, alcohol injectors, and fuel metering units, it controls the alcohol injection quantity, fuel injection quantity, injection advance angle, and fuel rail pressure under different substitution rates. This can actively pre-control the occurrence of misfire and knock in the transient process of the engine, ensuring the stability of the operating condition switching process between transient and steady states, and ensuring flexible combustion and durable reliability throughout the entire life cycle of the dual-fuel engine. Attached Figure Description
[0016] Figure 1 This is a logic flowchart of the dual-fuel engine knock and misfire pre-control method of the present invention;
[0017] Figure 2 This is a flowchart for judging transient / steady-state operating conditions;
[0018] Figure 3 This is a flowchart of the slope control process during transient / problem switching;
[0019] Figure 4 This is a schematic diagram of the structural principle of the dual-fuel engine knock and misfire prevention control device of the present invention. Detailed Implementation
[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments. Preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the textual part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but they should not be construed as limiting the scope of protection of the present invention.
[0021] Example 1:
[0022] This application provides a method for preventing knock and misfire in a dual-fuel engine. The ECU (Electronic Control Unit, also known as "vehicle computer" or "on-board computer") contains steady-state substitution rate MAP, steady-state injection advance angle MAP, steady-state fuel rail pressure MAP, transient substitution rate MAP, transient injection advance angle MAP, and transient fuel rail pressure MAP. The aforementioned MAPs are tables formed by comparing the substitution rate, injection advance angle, fuel rail pressure, and related values of the engine under steady-state and transient operating conditions in dual-fuel mode, calibrated through bench tests, to ensure that the engine will not experience internal knock and misfire under both steady-state and transient operating conditions.
[0023] Specifically, the substitution rate MAP is a table that controls the proportion of methanol in dual-fuel mode. The X-axis represents the engine speed, the Y-axis represents the current intake air volume of the engine, and the Z-axis represents the proportion of methanol per cycle when the engine is running in dual-fuel mode. Its function is to achieve different substitution rates at different speeds and loads.
[0024] Advance Angle (MAP): A table for controlling the timing of diesel injection in dual-fuel mode. The X-axis represents engine speed, the Y-axis represents the current intake air volume of the engine, and the Z-axis represents the current injection timing of the engine when running in dual-fuel mode. Its function is to achieve different diesel injection timings at various speeds and loads.
[0025] MAP (Mount Pressure Map): A table for controlling fuel rail pressure in dual-fuel mode. The X-axis represents engine speed, the Y-axis represents the current circulating fuel volume of the engine, and the Z-axis represents the current fuel rail pressure when the engine is running in dual-fuel mode. Its function is to achieve different fuel rail pressures at various speeds and loads.
[0026] like Figure 1As shown, the knock and misfire prevention method for a dual-fuel engine claimed in this application specifically includes: when the engine enters dual-fuel mode, collecting engine operating parameters and identifying transient and steady-state operating conditions based on these parameters; the ECU selects the corresponding transient or steady-state substitution rate MAP, fuel injection advance angle MAP, and fuel rail pressure MAP based on the operating condition judgment result; the ECU outputs the substitution rate, injection advance angle, and fuel rail pressure from the current MAP lookup table value to the transient or steady-state MAP lookup table value corresponding to the current engine operating parameters. The ECU transmits the corresponding operating values to the actuators, namely the injector, alcohol injector, and fuel metering unit, to control the alcohol injection quantity, fuel injection quantity, injection advance angle, and fuel rail pressure under different substitution rates, which can reduce the risk of knock and misfire in the methanol dual-fuel engine under all operating conditions.
[0027] When the engine is operating under transient or steady-state-to-transient conditions, the ECU employs steady-state-to-transient control (S→T), rapidly adjusting the substitution rate, injection advance angle, and fuel rail pressure to the corresponding transient MAP lookup values to ensure rapid engine response under transient conditions. When the engine is operating under steady-state conditions or transient-to-steady-state conditions, the ECU employs transient-to-steady-state control (T→S), slowly adjusting the substitution rate, injection advance angle, and fuel rail pressure to the corresponding steady-state MAP lookup values to ensure engine stability under steady-state conditions.
[0028] Specifically, steady-state to transient control (S→T) and transient to steady-state control (T→S) involve linearizing the MAP lookup values of the current substitution rate, injection advance angle, and fuel rail pressure according to different rates of change, transitioning them to the corresponding transient or steady-state MAP lookup values. This rate of change (k...) t k p k R This refers to the linear control slope. Based on the switching direction between transient and steady-state conditions, it calls and outputs the linear control slope of the substitution rate, injection advance angle, and fuel rail pressure corresponding to the switching direction. This ensures the stability of the operating condition switching process between transient and steady-state conditions and further reduces the risk of engine knock and misfire.
[0029] Among them, the rates of change of substitution rate, injection advance angle, and fuel rail pressure during the transition from steady-state to transient control are greater than those during the transition from transient to steady-state control. That is, the rate of change k of the substitution rate during the transition from steady-state to transient control is defined as: t Let a be the rate of change of the injection advance angle, k. p For b, the rate of change of fuel rail pressure k R For c; the rate of change k of the substitution rate during transient-to-steady-state control. t Let a0 be the rate of change of the injection advance angle k. p For b0, the rate of change of fuel rail pressure k RLet c0 be the value of c. Then a > a0, b > c0, and b > c0.
[0030] In this application, the following parameters can be specified: a = 10% / s, b = 4°CA / s, c = 20MPa / s, a0 = 0.5% / s, b0 = 2°CA / s, c0 = 5MPa / s. It should be noted that different models of methanol-diesel dual-fuel engines may have different requirements for the rate of change of substitution rate, injection advance angle, and fuel rail pressure during the transition between steady-state and transient operating conditions under different operating environments. Operators need to set these parameters appropriately according to their specific needs. This application only provides an example of a preferred solution.
[0031] In summary, as Figure 3 As shown, after the ECU's transient / steady-state coordinator outputs the operating condition status and it is confirmed by the hysteresis controller, the subsequent control method of the engine is as follows:
[0032] (1) When the engine is in transient operation or steady-state-to-transient operation, the ECU adopts steady-state-to-transient control (S→T), and the rate of change of the substitution rate (control slope) k t The rate of change of the injection advance angle is 10% / s, k p The rate of change of fuel rail pressure is 4°CA / s, k R The pressure is 20 MPa / s. The substitution rate, injection advance angle and fuel rail pressure are rapidly and linearly controlled from the current MAP value to the transient MAP lookup value corresponding to the current operating condition parameters.
[0033] (2) When the engine is in steady-state operation or transient-to-steady-state operation, the ECU adopts transient-to-steady-state control (T→S), and the rate of change of the substitution rate k t The rate of change of the injection advance angle is 0.5% / s, k p The rate of change of fuel rail pressure is 2°CA / s, k R The pressure is 5 MPa / s. The substitution rate, injection advance angle and fuel rail pressure are slowly and linearly controlled from the current MAP value to the steady-state MAP lookup value corresponding to the current operating condition parameters.
[0034] The following describes how to identify transient and steady-state operating conditions of an engine based on its operating parameters.
[0035] Steady-state operating conditions refer to the operating conditions under which the engine's operating parameters remain basically stable over a relatively long period of time, such as engine speed, intake air volume, and load. Transient operating conditions refer to situations where the engine's state changes rapidly, such as acceleration, deceleration, or a sudden increase in load. Therefore, some parameters can reflect the engine's operating condition.
[0036] like Figure 2As shown, the operating parameters required for determining the engine operating condition in this application include: actual engine speed n, target speed n0, mode status, current intake air volume A, and fault status. Here, actual speed n is the value measured by the speed sensor, target speed n0 is the value measured by the throttle position sensor, and current intake air volume A is the intake air flow rate after boosting detected by the sensor. When the engine is running in dual-fuel mode, the mode status is 1; when the engine reports no fault, the fault status is 1.
[0037] The method for determining whether the engine is operating in steady-state or transient-to-steady-state conditions is as follows: when the deviation between the actual engine speed n and the target speed n0 is less than a first set value C, the rate of change of engine speed ΔV / Δt within time Δt is less than a second set value B, the deviation between the current intake air volume A and the filtered intake air volume A0 is less than a third set value A, and no fault is reported, then the engine is determined to be operating in steady-state conditions. Here, the filtered intake air volume A0 is the value after the ECU filters and de-jitters the current intake air volume A.
[0038] The method for determining whether an engine is in transient or steady-state-transient operating condition is as follows: when the deviation between the actual engine speed n and the target speed n0 is greater than the first set value C, or the rate of change of speed ΔV / Δt within time Δt is greater than the second set value B, or the deviation between the current intake air volume A and the filtered intake air volume A0 is greater than the third set value A, the engine is determined to be in transient or steady-state-transient operating condition.
[0039] The first setting value C can be calibrated to 5 r / min, the second setting value B can be calibrated to 5 r / s, and the third setting value A can be calibrated to 10 kg / h.
[0040] Specifically, the steady-state and transient operating conditions of an engine can be divided into the following three cases:
[0041] (1) When the engine is under constant load and variable speed, the speed deviation between the current actual speed n and the target speed n0 is greater than C.
[0042] (2) When the engine is under the condition of simultaneous variable load and variable speed, within the time Δt, the engine speed change rate ΔV / Δt is greater than B; the speed deviation between the current actual speed n and the target speed n0 is greater than C; and the deviation between the current actual intake volume A and the filtered intake volume A0 is greater than A.
[0043] (3) When the engine is under variable load and constant speed conditions, the deviation between the current actual intake volume A and the filtered intake volume A0 is greater than A.
[0044] The three steady-state to transient operating conditions mentioned above are all included in the judgment method of engine transient operating condition or steady-state to transient operating condition. Combining the judgment of engine steady-state operating condition or transient to steady-state operating condition can cover all engine operating conditions. The ECU will output the transient state and perform steady-state to transient control to achieve flexible combustion and stable operation of the engine under all operating conditions, and reduce the risk of knocking and misfire of methanol dual-fuel engine under all operating conditions.
[0045] Example 2:
[0046] This application also provides a dual-fuel engine knock and misfire prevention control device. It should be noted that the dual-fuel engine knock and misfire prevention control device of this embodiment can be used to execute the dual-fuel engine knock and misfire prevention control method provided in Embodiment 1 of this application. The device is used to implement the above embodiments and preferred embodiments, and will not be repeated as described thereon.
[0047] like Figure 4 As shown, a dual-fuel engine knock and misfire prevention control device includes: an ECU and a dual-fuel mode switching switch electrically connected to the ECU, a boost air pressure sensor, an engine speed sensor, a throttle position sensor, a fuel common rail pressure sensor, a fuel injection pump, and an alcohol injector; the ECU is configured with a first setpoint, a second setpoint, a third setpoint, a steady-state substitution rate MAP, a steady-state injection advance angle MAP, a steady-state fuel rail pressure MAP, a transient substitution rate MAP, a transient injection advance angle MAP, and a transient fuel rail pressure MAP.
[0048] Combination Figures 1 to 4 As shown, after receiving the dual-fuel mode switching switch activation signal, the ECU identifies the engine's steady-state and transient operating conditions based on the deviation between the current engine speed and the target speed, the rate of change of engine speed, and the deviation between the current intake air volume and the filtered intake air volume. Depending on the direction of the transient / steady-state switching, the ECU linearizes the currently operating substitution rate, injection advance angle, and fuel rail pressure using different rates of change to transition to the corresponding transient or steady-state MAP lookup values. Finally, the ECU transmits the real-time calculated substitution rate, injection advance angle, and fuel rail pressure to the actuators—the fuel injector, alcohol injector, and fuel metering unit—to control the execution of alcohol injection quantity, fuel injection quantity, injection advance angle, and fuel rail pressure under different substitution rates.
[0049] Specifically, the ECU includes: a memory, a transient / steady-state coordinator, a hysteresis controller, a steady-state MAP selector, a transient MAP selector, a slope controller, and a parameter arbitrator. The memory stores preset first, second, and third setpoints, as well as steady-state substitution rate MAP, steady-state injection advance angle MAP, steady-state fuel rail pressure MAP, transient substitution rate MAP, transient injection advance angle MAP, and transient fuel rail pressure MAP. These setpoints and MAPs are calibrated through bench testing. The first, second, and third setpoints are respectively the engine speed deviation setpoint, engine speed change rate setpoint, and intake air volume deviation setpoint.
[0050] The transient / steady-state coordinator is used to collect and calculate the deviation between the current engine speed and the target speed, the rate of change of speed, and the deviation between the current intake air volume and the filtered intake air volume based on the parameters of each sensor. It identifies and outputs the transient and steady-state operating conditions of the engine by comparing the calculated values with the corresponding set values.
[0051] The hysteresis controller receives the operating condition signal output by the transient / steady-state coordinator. When it is confirmed that the comparison result in the transient / steady-state coordinator is not caused by a sudden change due to disturbance, it outputs the operating condition signal as the final operating condition signal.
[0052] The steady-state MAP selector is used to receive the operating condition signal output by the hysteresis controller, and retrieve the steady-state substitution rate MAP, steady-state injection advance angle MAP, steady-state fuel rail pressure MAP from the memory according to the signal, or not output.
[0053] The transient MAP selector is used to receive the operating condition signal output by the hysteresis controller, and retrieve the transient substitution rate MAP, transient injection advance angle MAP, transient fuel rail pressure MAP from the memory according to the signal, or not output them.
[0054] The slope controller is used to receive the MAP output from the steady-state MAP selector or the transient MAP selector, and to switch the substitution rate, injection advance angle and fuel rail pressure change rate of the corresponding operating condition according to the MAP output.
[0055] The parameter arbitrator receives the rate of change of substitution rate, injection advance angle and fuel rail pressure from the slope controller, and calculates the current required substitution rate, injection advance angle and fuel rail pressure by combining the substitution rate, injection advance angle and fuel rail pressure from the previous cycle, and outputs them to the actuators, namely the injectors, fuel injectors and fuel metering unit.
[0056] The dual-fuel engine knock and misfire prevention method and device of the present invention identifies transient and steady-state operating conditions based on engine operating parameters. The ECU switches the substitution rate, injection advance angle and fuel rail pressure output to the actuator from the current MAP lookup value to the transient or steady-state MAP lookup value corresponding to the current engine operating parameters based on the operating condition judgment result. This can reduce the risk of knock and misfire in methanol dual-fuel engines under all operating conditions.
[0057] In the description of this specification, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Unless otherwise expressly defined, terms such as "set," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.
[0058] It should be noted that the methods described in the embodiments disclosed above can be implemented directly using hardware, software modules executed by a processor, or a combination of both. Software modules can be stored in any other form of storage medium known in the art, such as electrically programmable ROMs, electrically erasable programmable ROMs, microcontrollers, or processors. To clearly illustrate the interchangeability of hardware and software, parts of the ECU have been generally described in the above description according to functional modules, such as: memory, transient / steady-state coordinator, hysteresis controller, steady-state MAP selector, transient MAP selector, slope controller, and parameter arbitrator. These functional modules can be a processing chip integrating algorithms; or they can be program code stored in a storage medium. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution, and no restrictions are placed here.
[0059] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the described embodiments are merely some, not all, of the present invention. These are merely illustrative examples, and the scope of protection of the present invention is defined by the claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention and without any inventive effort, but all such changes and modifications fall within the scope of protection of the present invention.
Claims
1. A method for pre-controlling knock and misfire in a dual-fuel engine, characterized in that, include: The ECU is configured with steady-state substitution rate MAP, steady-state injection advance angle MAP, steady-state fuel rail pressure MAP, transient substitution rate MAP, transient injection advance angle MAP, and transient fuel rail pressure MAP. When the engine enters dual-fuel mode, engine operating parameters are collected, and transient and steady-state operating conditions are identified based on these parameters. Based on the operating condition judgment result, the ECU selects the corresponding transient or steady-state substitution rate MAP, fuel injection advance angle MAP, and fuel rail pressure MAP. The substitution rate, injection advance angle, and fuel rail pressure output by the ECU are switched from the current MAP lookup value to the transient or steady-state MAP lookup value corresponding to the current engine operating condition parameters.
2. The method according to claim 1, characterized in that, When the engine is in transient operating condition or steady-state-to-transient operating condition, the ECU adopts steady-state-to-transient control, and the substitution rate, the injection advance angle and the fuel rail pressure are quickly adjusted to the corresponding transient MAP lookup values. When the engine is in steady-state operation or transient-to-steady-state operation, the ECU adopts transient-to-steady-state control, and the substitution rate, the injection advance angle and the fuel rail pressure are slowly adjusted to the corresponding steady-state MAP lookup values.
3. The method according to claim 2, characterized in that, The steady-state to transient control and the transient to steady-state control are achieved by linearizing the MAP lookup values of the current substitution rate, injection advance angle, and fuel rail pressure according to different rates of change, and transitioning them to the corresponding transient or steady-state MAP lookup values.
4. The method according to claim 3, characterized in that, The rate of change of the substitution rate, the injection advance angle, and the fuel rail pressure during the transition from steady-state to transient control is greater than the rate of change of the substitution rate, the injection advance angle, and the fuel rail pressure during the transition from transient to steady-state control.
5. The method according to claim 4, characterized in that, During the steady-state to transient control, the rate of change of the substitution rate is 10% / s, the rate of change of the injection advance angle is 4°CA / s, and the rate of change of the fuel rail pressure is 20MPa / s. During the transient-to-steady-state control, the rate of change of the substitution rate is 0.5% / s, the rate of change of the injection advance angle is 2°CA / s, and the rate of change of the fuel rail pressure is 5MPa / s.
6. The method according to claim 1, characterized in that, The operating parameters include the engine's actual speed, target speed, mode status, current intake air volume, and fault status. The actual rotational speed is the value measured by the rotational speed sensor; The target rotational speed is the value measured by the throttle position sensor; The current intake volume is the boosted intake flow rate detected by the sensor; When the engine enters dual-fuel mode, the mode state is 1. When the engine reports no fault, the fault status is 1.
7. The method according to claim 6, characterized in that, When the deviation between the actual speed of the engine and the target speed is less than the first set value, the rate of change of speed ΔV / Δt within time Δt is less than the second set value, the deviation between the current intake volume and the filtered intake volume is less than the third set value, and no fault is reported, then the engine is judged to be in steady-state operation or transient-to-steady-state operation. The filtered intake volume is the value after the ECU filters and de-jitters the current intake volume value.
8. The method according to claim 7, characterized in that, When one or more of the following conditions are met: the actual speed of the engine deviates from the target speed by more than the first set value; the rate of change of speed ΔV / Δt within time Δt is greater than the second set value; or the deviation between the current intake volume and the filtered intake volume is greater than the third set value, the engine is determined to be in transient operating condition or steady-state-to-transient operating condition.
9. A knock and misfire prevention control device for a dual-fuel engine, characterized in that, include: The ECU and the dual-fuel mode switch electrically connected to the ECU, the boost air pressure sensor, the engine speed sensor, the throttle position sensor, the common rail fuel pressure sensor, the fuel injection pump, and the alcohol injector; The ECU is configured with a first set value, a second set value, a third set value, a steady-state substitution rate MAP, a steady-state injection advance angle MAP, a steady-state fuel rail pressure MAP, a transient substitution rate MAP, a transient injection advance angle MAP, and a transient fuel rail pressure MAP. After receiving the activation signal of the dual-fuel mode switching switch, the ECU identifies the steady-state and transient operating conditions of the engine based on the deviation between the current engine speed and the target speed, the speed change rate, and the deviation between the current intake air volume and the filtered intake air volume. According to the switching direction between transient and steady state, the ECU linearizes the current operating substitution rate value, injection advance angle value, and fuel rail pressure by using different change rates to transition to the corresponding transient or steady-state MAP lookup value. The ECU transmits the real-time calculated substitution rate, injection advance angle, and fuel rail pressure to the injectors, alcohol injectors, and fuel metering unit to control the execution of alcohol injection quantity, fuel injection quantity, injection advance angle, and fuel rail pressure under different substitution rates.
10. The apparatus according to claim 9, characterized in that, The ECU includes: The transient / steady-state coordinator is used to collect and calculate the deviation between the current engine speed and the target speed, the rate of change of engine speed, and the deviation between the current intake air volume and the filtered intake air volume based on the parameters of each sensor. It identifies and outputs the transient and steady-state operating conditions of the engine by comparing the calculated values with the set values. The hysteresis controller receives the operating condition signal output by the transient / steady-state coordinator. When it is confirmed that the comparison result in the transient / steady-state coordinator is not caused by a sudden change due to interference, it outputs the operating condition signal as the final operating condition signal. The steady-state MAP selector is used to receive the operating condition signal output by the hysteresis controller, and retrieve the steady-state substitution rate MAP, steady-state injection advance angle MAP, steady-state fuel rail pressure MAP from the memory according to the signal, or not output them. The transient MAP selector is used to receive the operating condition signal output by the hysteresis controller, and retrieve the transient substitution rate MAP, transient injection advance angle MAP, transient fuel rail pressure MAP from the memory according to the signal, or not output them. The slope controller is used to receive the MAP output by the steady-state MAP selector or the transient MAP selector, and output the substitution rate, injection advance angle and fuel rail pressure change rate of the corresponding operating condition switching direction according to the MAP. The parameter arbitrator is used to receive the rate of change of the substitution rate, injection advance angle and fuel rail pressure output by the slope controller, and calculate the current required substitution rate, injection advance angle and fuel rail pressure in combination with the substitution rate, injection advance angle and fuel rail pressure of the previous cycle, and output them to the injector, fuel injector and fuel metering unit.