Method and system for controlling process from starting to idling of dual-fuel engine

Abstract

The invention belongs to the field of dual-fuel engine starting, and particularly discloses a control method and system for the process from starting to idling of a dual-fuel engine, and the method comprises the steps that the diesel oil injection quantity, the injection advance angle, the diesel oil rail pressure and the throttle valve required opening degree in the engine starting process are obtained; starting an engine according to the fuel injection quantity and the injection advance angle; judging whether the rotating speed of the engine exceeds an idling takeover value; if the engine is not started again, the diesel injection advance angle is delayed in the starting process, the fuel injection quantity is increased, and the idling set value is triggered to be gradually transited to the final idling target value from the idling takeover value until the rotating speed of the engine exceeds the idling takeover value; if yes, directly triggering the idling set value to gradually transit to the final idling target value from the idling takeover value; and after the idle speed is stable, the injection quantity and the injection advance angle of the diesel oil are gradually transited to the injection quantity and the injection advance angle of micro-injection ignition.

Description

Technical Field

[0001] This invention belongs to the field of dual-fuel engine starting, specifically relating to a control method and system for the process of starting a dual-fuel engine to idling. Background Technology

[0002] When starting a dual-fuel engine (usually referring to diesel-natural gas dual-fuel), it must first run in pure diesel mode. This is because natural gas requires higher temperatures and energy to ignite reliably, while diesel's compression ignition characteristics (generating high-temperature auto-ignition through compression) can provide the engine with initial stable operating conditions.

[0003] Once the engine reaches a stable operating state in diesel mode (with normal parameters such as water temperature and oil temperature), it can smoothly switch to "dual-fuel mode," where most of the fuel is provided by natural gas, and only a small amount of diesel is used as "ignition fuel" to ignite the natural gas.

[0004] A starting method and apparatus for a dual-fuel engine is disclosed in the prior art: when controlling the dual-fuel engine to perform the starting operation, the first intake air volume and the second intake low-pressure gas volume required for the dual-fuel engine to start are calculated based on the starting torque of the dual-fuel engine. The first intake air volume and the second intake low-pressure gas volume are ignited by diesel fuel in the cylinder to control the dual-fuel engine to perform the starting operation. The air and low-pressure gas first enter the intake manifold and mix in the intake manifold before entering the cylinder. It does not require high-pressure direct injection in the cylinder. However, this starting method may result in the engine failing to start multiple times. Summary of the Invention

[0005] In order to solve the technical problems existing in the prior art, the present invention discloses a control method and system for the start-up to idling process of a dual-fuel engine.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: In a first aspect, the present invention provides a control method for the start-up to idle process of a dual-fuel engine, comprising the following steps: Obtain the diesel fuel injection quantity, injection advance angle, diesel rail pressure, and throttle opening requirements during engine start-up; Start the engine based on the injection quantity, injection advance angle, diesel rail pressure, and required throttle opening. Determine if the engine speed exceeds the idle speed control value. If not, restart the engine, and during this restart process, delay the diesel injection advance angle and increase the injection quantity until the engine speed exceeds the idle speed control value. Then, trigger the idle speed setpoint to gradually transition from the idle speed control value to the final idle speed target value. If yes, directly trigger the idle speed setpoint to gradually transition from the idle speed control value to the final idle speed target value. After the idle speed stabilizes, the diesel injection quantity and diesel injection advance angle are gradually transitioned to the injection quantity and diesel injection advance angle of micro-injection ignition.

[0007] As a further technical solution, when the engine starts successfully, the start-up injection advance angle is updated to the injection advance angle pulse spectrum (MAP) based on engine speed and water temperature.

[0008] As a further technical solution, when the engine starts successfully, the diesel injection quantity that can be successfully started is updated in the diesel injection quantity pulse spectrum (MAP) based on engine speed and water temperature.

[0009] As a further technical solution, the delayed diesel injection angle must not exceed a set threshold; if it does, a fault is triggered.

[0010] As a further technical solution, the increased diesel injection quantity must not exceed a set threshold; if it does, a fault will be triggered.

[0011] Secondly, the present invention provides a control system for the start-up to idle process of a dual-fuel engine, comprising the following steps: The acquisition module is configured to acquire the diesel fuel injection quantity, injection advance angle, diesel rail pressure, and throttle opening requirements during the engine start-up process. The start-up module is configured to start the engine based on the fuel injection quantity, injection advance angle, diesel rail pressure, and throttle opening requirements. The judgment module is configured to determine whether the engine speed exceeds the idle speed control value; if not, the engine is restarted, and the restart process delays the diesel injection advance angle and increases the injection quantity until the engine speed exceeds the idle speed control value, then the idle speed setpoint is triggered to gradually transition from the idle speed control value to the final idle speed target value; if yes, then the idle speed setpoint is directly triggered to gradually transition from the idle speed control value to the final idle speed target value. The transition module is configured so that after the idle speed stabilizes, the diesel injection quantity and diesel injection advance angle gradually transition to the injection quantity and diesel injection advance angle of the micro-injection ignition.

[0012] As a further technical solution, the judgment module is also configured to update the start-up injection advance angle to the injection advance angle pulse spectrum based on engine speed and water temperature when the engine starts successfully.

[0013] As a further technical solution, the judgment module is also configured to update the diesel injection quantity that enables successful engine start-up to the diesel injection quantity pulse spectrum based on engine speed and water temperature when the engine starts successfully.

[0014] As a further technical solution, the judgment module is also configured such that the delayed diesel injection angle cannot exceed a set threshold, and if it exceeds the set threshold, a fault is triggered.

[0015] As a further technical solution, the judgment module is also configured such that the increased diesel injection quantity cannot exceed a set threshold, and if it exceeds the set threshold, a fault is triggered.

[0016] Thirdly, the present invention also provides a starting device, which may include a memory and a processor, wherein the memory is used to store program instructions; the processor is used to read the program instructions in the memory and execute the control method for the starting to idle process of the dual-fuel engine according to any one of the first aspects.

[0017] Fourthly, the present invention also provides a computer storage medium including instructions that, when executed by one or more processors, cause a starting device to perform the control method for the starting to idle process of a dual-fuel engine as described in any of the first aspects.

[0018] The beneficial effects of this invention are as follows: The method proposed in this invention helps to improve the success rate of engine starting by increasing the amount of diesel fuel for ignition and delaying the advance of diesel fuel injection. At the same time, after the starting speed exceeds the idle speed control value, the idle speed control stage is entered. The idle speed setpoint is then subjected to transition control, that is, the idle speed setpoint gradually increases from the idle speed control value to the final idle speed setpoint. This makes the transition stage from successful engine start to idle speed control smoother. Attached Figure Description

[0019] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0020] Figure 1 This is a flowchart of the control method proposed in this invention; Figure 2 This is a schematic diagram of the control system proposed in this invention; In the diagram: 201 Acquisition module, 202 Startup module, 203 Judgment module, 204 Transition module; Detailed Implementation It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0021] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless otherwise expressly indicated by the invention, the singular form is also intended to include the plural form. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. Definition: The PID control algorithm in this invention is a control method that uses a linear combination of the proportional (P), integral (I), and derivative (D) values ​​of the deviation.

[0022] In this invention, the idle speed control refers to a process where, instead of using a closed-loop speed control to determine the required throttle opening during engine startup, the required throttle opening is determined directly based on engine speed and coolant temperature. Only after the working fluid in the engine cylinders has burned and performed work, and the engine speed has increased to the idle speed control speed (e.g., 350 rpm), does the speed closed-loop operation occur, meaning the actual engine speed and the set idle speed are closed in a loop. Therefore, the idle speed control acts as a dividing point between the engine startup state and the idle state.

[0023] As described in the background section, existing technologies have shortcomings. To address the aforementioned technical problems, this invention proposes a control method and system for the start-up and idling process of a dual-fuel engine. First, the diesel injection quantity, injection advance angle, diesel rail pressure, and throttle opening requirements during engine start-up are acquired. Based on these parameters, the engine is started. Then, it is determined whether the engine speed exceeds the idle speed control value. If not, the engine is started again, and this start-up process delays the diesel injection advance angle and increases the injection quantity until the engine speed exceeds the idle speed control value. At this point, the idle speed setpoint is gradually transitioned from the idle speed control value to the final idle speed target value. If the engine speed exceeds the idle speed control value, the idle speed setpoint is directly transitioned from the idle speed control value to the final idle speed target value. After the idle speed stabilizes, the diesel injection quantity and injection advance angle are gradually transitioned to the injection quantity and injection advance angle of the micro-injection ignition system. The method proposed in this invention helps to improve the success rate of engine starting by increasing the amount of diesel fuel for ignition and delaying the advance of diesel fuel injection. At the same time, after the starting speed exceeds the idle speed control value, the idle speed control stage is entered. The idle speed setpoint is then subjected to transition control, that is, the idle speed setpoint gradually increases from the idle speed control value to the final idle speed setpoint. This makes the transition stage from successful engine start to idle speed control smoother.

[0024] Example 1 In a typical embodiment of the present invention, such as Figure 1As shown, this embodiment provides a control method for the start-up to idle process of a dual-fuel engine. Currently, in models where direct-injection diesel ignites alternative fuels injected through manifolds or central injection, there is a problem of insufficient ignition of micro-injected diesel during the start-up process. The main reasons are: low water temperature, low intake air temperature, and low cylinder temperature before starting, which are not conducive to the complete ignition of diesel injected into the cylinder. This embodiment optimizes the start-up process by correcting the amount of diesel injected based on the water temperature and intake air temperature at the time of start-up, appropriately increasing the amount of diesel and appropriately delaying the diesel injection advance angle. Furthermore, during the start-up process (not a closed-loop speed control but controlled by checking the feedforward throttle opening based on the current speed and water temperature), when the engine speed exceeds the idle speed control gate speed (after the idle speed control gate enters the closed-loop PID control) speed (e.g., 350 r / min), the idle speed setpoint is changed from 350 r / min. The speed gradually transitions to the final idle speed setpoint of 700 rpm. At this point, the speed deviation is 700 rpm - 350 rpm = 350 rpm. This means that if the starting speed exceeds the idle speed control unit speed of 350 rpm, but the idle speed setpoint remains at 700 rpm, the closed-loop speed control output will be too large, resulting in excessive working fluid entering the cylinder for combustion and causing speed overshoot. Solving this problem requires time and involves calibrating the PID controller to reduce speed overshoot. This embodiment addresses this overshoot problem by ramping the idle speed setpoint. The control method for the dual-fuel engine from start-up to idle proposed in this embodiment includes the following steps: S101. Obtain the diesel fuel injection quantity, injection advance angle, diesel rail pressure, and throttle opening requirement during engine start-up. Specifically, based on engine speed, intake air temperature, and coolant temperature, check the diesel fuel injection quantity, injection advance angle, and diesel rail pressure during start-up; and based on engine speed, intake air temperature, and coolant temperature, check the throttle opening requirement during start-up.

[0025] S102. Start the engine according to the stated fuel injection quantity and injection advance angle; S103. Determine if the engine speed exceeds the idle speed control value; if not, restart the engine, and during this restart process, delay the diesel injection advance angle and increase the injection quantity until the engine speed exceeds the idle speed control value, then trigger the idle speed setpoint to gradually transition from the idle speed control value to the final idle speed target value; if yes, then directly trigger the idle speed setpoint to gradually transition from the idle speed control value to the final idle speed target value. S104. After the idle speed stabilizes, the diesel injection quantity and diesel injection advance angle are gradually transitioned to the injection quantity and diesel injection advance angle of the micro-injection ignition.

[0026] The reason for delaying the diesel injection advance angle during the above-mentioned start-up process is that the diesel injection advance angle is generally before the piston's top dead center during compression. If the diesel injection advance angle is too large, the piston moves upward, but the working fluid in the combustion chamber is relatively cold. Although diesel is injected, it is not conducive to the compression ignition of diesel. A lot of unburned diesel is injected onto the cylinder wall and piston top surface, forming large liquid particles that are even more difficult to ignite. If the diesel injection advance angle is delayed further, when the piston moves upward and the combustion chamber space is smaller, the air temperature and pressure in the combustion chamber are very high. At this time, injecting diesel is more conducive to the compression ignition of diesel. Therefore, appropriately delaying the diesel injection advance angle can facilitate engine start-up.

[0027] Furthermore, if the above-mentioned start-up fails, the diesel injection advance angle will be delayed in the next start-up process until the start-up is successful. However, the delayed diesel injection angle cannot exceed a certain threshold. If the threshold is exceeded, a fault will be reported. If the start-up is successful, the start-up injection advance angle will be updated in the injection advance angle MAP based on engine speed and coolant temperature. Similarly, the diesel injection quantity during the start-up process will gradually increase after the start-up fails, but there is a certain limit. If the limit is exceeded, a fault will be reported. If the start-up is successful, the diesel injection quantity for successful start-up will be updated in the diesel injection quantity MAP based on engine speed and coolant temperature.

[0028] Furthermore, after the engine starts successfully (the engine speed is judged to have started successfully based on whether the engine speed exceeds a speed threshold called the idle speed control speed, such as 350 r / min), once the engine starting speed exceeds the idle speed control speed setting value, the engine speed control becomes a closed-loop control between the actual speed and the idle speed setting speed. Then the setting speed gradually transitions from the idle speed control speed setting value to the final target idle speed setting value.

[0029] Furthermore, after the idle speed stabilizes, based on parameters such as water temperature, the diesel injection quantity and diesel injection advance angle are gradually transitioned to the diesel quantity and diesel injection advance angle ignited by micro-injection.

[0030] Furthermore, although the engine start-up process uses the throttle valve to control the amount of fuel gas to generate engine combustion energy to overcome the friction torque during the start-up process, the amount of diesel fuel used as ignition fuel also needs to be adjusted. If the water temperature or intake air temperature is too low, the amount of diesel fuel used for ignition needs to be increased and the diesel fuel injection advance angle needs to be delayed, which helps to improve the success rate of starting the engine.

[0031] Example 2 Based on the control method for the dual-fuel engine start-up to idle speed process disclosed in Embodiment 1, this embodiment provides a control system for the dual-fuel engine start-up to idle speed process, including an acquisition module 201, a start-up module 202, a judgment module 203, and a transition module 204. The specific functions of each module are as follows: The acquisition module 201 is configured to acquire the amount of diesel fuel injected, the injection advance angle, the diesel rail pressure, and the required throttle opening during the engine start-up process. The start module 202 is configured to start the engine according to the fuel injection quantity, injection advance angle, diesel rail pressure and throttle opening requirements. The judgment module 203 is configured to determine whether the engine speed exceeds the idle speed control value; if not, the engine is restarted again, and the restart process delays the diesel injection advance angle and increases the injection quantity until the engine speed exceeds the idle speed control value, then the idle speed setpoint is triggered to gradually transition from the idle speed control value to the final idle speed target value; if yes, then the idle speed setpoint is directly triggered to gradually transition from the idle speed control value to the final idle speed target value. The transition module 204 is configured so that after the idle speed stabilizes, the diesel injection quantity and diesel injection advance angle gradually transition to the injection quantity and diesel injection advance angle of the micro-injection ignition.

[0032] In the above system, the judgment module 203 is also configured to update the start-up injection advance angle to the injection advance angle pulse spectrum based on engine speed and water temperature when the engine starts successfully.

[0033] In the above system, the judgment module 203 is also configured to update the diesel injection quantity that enables successful engine start-up to the diesel injection quantity pulse spectrum based on engine speed and water temperature when the engine starts successfully.

[0034] In the above system, the judgment module 203 is also configured such that the delayed diesel injection angle cannot exceed a set threshold, and if it exceeds the set threshold, a fault is triggered.

[0035] In the above system, the judgment module 203 is also configured such that the increased diesel injection quantity cannot exceed a set threshold, and if it exceeds the set threshold, a fault is triggered.

[0036] Example 3 Furthermore, the present invention provides a starting device, which may include a processor and a memory, wherein: the memory is used to store program instructions; the processor is used to read the program instructions in the memory and execute the technical solution of the control method for the dual-fuel engine starting to idling process shown in any of the above embodiments according to the program instructions in the memory. Its implementation principle and beneficial effects are similar to those of the control method for the dual-fuel engine starting to idling process, and will not be described again here.

[0037] Example 4 This invention also provides a computer storage medium including instructions that, when executed by one or more processors, cause a starting device to perform the control method for the dual-fuel engine start-to-idle process shown in any of the above embodiments. The implementation principle and beneficial effects are similar to those of the control method for the dual-fuel engine start-to-idle process, and will not be described again here.

[0038] In the above embodiments, the processor can be a general-purpose processor, a digital signal processor, an application-specific integrated circuit (ASIC), an off-the-shelf programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of this invention. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this invention can be directly manifested as execution by a hardware decoding processor, or execution by a combination of hardware and software modules in the decoding processor. The software modules can reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory; the processor reads instructions from the memory and, in conjunction with its hardware, completes the steps of the above methods.

[0039] In the several embodiments provided by this invention, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0040] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, the functional units in the various embodiments of this invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated units described above can be implemented in hardware or in a combination of hardware and software functional units.

[0041] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A control method for the start-up to idle process of a dual-fuel engine, characterized in that, Includes the following steps: Obtain the diesel fuel injection quantity, injection advance angle, diesel rail pressure, and throttle opening requirements during engine start-up; Start the engine based on the injection quantity, injection advance angle, diesel rail pressure, and required throttle opening. Determine if the engine speed exceeds the idle speed control value; If the engine is restarted, and the restart process delays the diesel injection advance angle and increases the injection quantity until the engine speed exceeds the idle speed control value, then the idle speed setpoint will gradually transition from the idle speed control value to the final idle speed target value; if so, then the idle speed setpoint will directly transition from the idle speed control value to the final idle speed target value. After the idle speed stabilizes, the diesel injection quantity and diesel injection advance angle are gradually transitioned to the injection quantity and diesel injection advance angle of micro-injection ignition.

2. The control method for the start-up to idle process of a dual-fuel engine as described in claim 1, characterized in that, When the engine starts successfully, the start-up injection advance angle is updated to the injection advance angle pulse spectrum based on engine speed and water temperature.

3. The control method for the start-up to idle process of a dual-fuel engine as described in claim 1, characterized in that, When the engine starts successfully, the diesel injection quantity that enables successful start-up is updated to the diesel injection quantity pulse spectrum based on engine speed and water temperature.

4. The control method for the start-up to idle process of a dual-fuel engine as described in claim 1, characterized in that, The delayed diesel injection angle must not exceed a set threshold; if it does, a fault will be triggered.

5. The control method for the start-up to idle process of a dual-fuel engine as described in claim 1, characterized in that, The increased diesel injection quantity must not exceed a set threshold; if it does, a fault will be triggered.

6. A control system for the start-up to idle process of a dual-fuel engine, characterized in that, as follows: The acquisition module is configured to acquire the diesel fuel injection quantity, injection advance angle, diesel rail pressure, and throttle opening requirements during the engine start-up process. The start-up module is configured to start the engine based on the fuel injection quantity, injection advance angle, diesel rail pressure, and throttle opening requirements. The judgment module is configured to determine whether the engine speed exceeds the idle speed control value; If the engine is restarted, and the restart process delays the diesel injection advance angle and increases the injection quantity until the engine speed exceeds the idle speed control value, then the idle speed setpoint will gradually transition from the idle speed control value to the final idle speed target value; if so, then the idle speed setpoint will directly transition from the idle speed control value to the final idle speed target value. The transition module is configured so that after the idle speed stabilizes, the diesel injection quantity and diesel injection advance angle gradually transition to the injection quantity and diesel injection advance angle of the micro-injection ignition.

7. The control system for the start-up to idle process of a dual-fuel engine as described in claim 6, characterized in that, The judgment module is also configured to update the start-up injection advance angle to the injection advance angle pulse spectrum based on engine speed and water temperature when the engine starts successfully.

8. The control system for the start-up to idle process of a dual-fuel engine as described in claim 6, characterized in that, The aforementioned judgment module is also configured to update the diesel injection quantity that enables successful engine start-up to the diesel injection quantity pulse spectrum based on engine speed and water temperature when the engine starts successfully.

9. The control system for the start-up to idle process of a dual-fuel engine as described in claim 6, characterized in that, The judgment module is also configured such that the delayed diesel injection angle cannot exceed a set threshold; if it does, a fault is triggered.

10. The control system for the start-up to idle process of a dual-fuel engine as described in claim 6, characterized in that, The judgment module is also configured such that the increased diesel injection quantity cannot exceed a set threshold; if it does, a fault is triggered.

11. A boot device, comprising a memory and a processor, wherein, The memory is used to store program instructions; characterized in that the processor is used to read the program instructions in the memory and execute the control method for the dual-fuel engine start-up to idle process according to any one of claims 1-5.

12. A computer storage medium, characterized in that, The instruction includes instructions that, when executed by one or more processors, cause the starting device to perform the control method for the dual-fuel engine start-up to idle process as described in any one of claims 1-5.

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