Method of operating engine, engine system, controller and program product

Abstract

The invention relates to a method of operating an engine, an engine system, a controller and a program product. The engine operates with natural gas as fuel and is provided with a natural gas tank. In a method of operating an engine, a filling event of a natural gas tank of the engine is detected; if a refueling event of the natural gas tank is detected, a knock protection mode of the engine is activated. Therefore, based on natural gas tank filling event identification, the knock protection mode is actively activated before the engine is knocked, and high-load strong knock caused by the fact that the engine uses low-octane natural gas is avoided.

Description

Technical Field

[0001] This application relates to the technical field of engines, and more particularly to the technical field of engines that operate using natural gas as fuel. More specifically, this application relates to a method of operating an engine, an engine system, a controller, and a program product. Background Technology

[0002] In the automotive industry, the engine is the core component and the power source of a car. It generates energy by burning fuel and converts this energy into mechanical energy to drive the car forward.

[0003] Traditional engines typically use gasoline or diesel as fuel. However, with increasingly scarce oil resources and soaring oil prices, the cost of fuel for major oil-importing countries has increased dramatically. This uncertainty in energy supply has prompted countries to seek alternative energy sources. On the other hand, with the growing prominence of global environmental problems, governments worldwide have introduced stringent emission regulations requiring reductions in vehicle emissions.

[0004] Therefore, to avoid over-reliance on a single energy source, countries have begun implementing energy diversification strategies. Furthermore, the demand for clean energy is increasing to protect the environment. Natural gas, as a clean and efficient energy source, is considered one of the important alternatives to oil. Compared to other fossil fuels, natural gas produces the least amount of pollutants throughout its entire life cycle—from extraction and production to storage, transportation, and use—and is therefore known as a "clean fuel." This clean fuel characteristic makes natural gas engines a promising candidate for application in today's increasingly stringent environmental regulations.

[0005] However, due to differences in the composition of natural gas from different sources, the composition of commercially available liquefied natural gas (LNG) for vehicles varies significantly between different regions, resulting in different octane ratings. Heavy-duty gas engines primarily operate under high loads and extreme external characteristics, making in-cylinder combustion highly sensitive to engine performance. Using lower octane fuel can increase the tendency for engine knocking, and severe knocking can damage internal engine components.

[0006] Current engine combustion is controlled using a set of basic combustion parameters (ignition angle, EGR rate, etc.), then calibrated with relevant corrections (coolant temperature correction, environmental correction, etc.), and finally protected by knock monitoring.

[0007] However, current engine knock monitoring is a passive protection mechanism. This means that the knock sensor can only detect the knock signal and respond by reducing the ignition advance angle (delaying combustion to suppress knock) after engine knocking has occurred. When a car is filled with low-octane natural gas and operates under high load or in its external characteristic range, severe knocking can easily occur before the knock protection activates, potentially damaging the engine. Summary of the Invention

[0008] The purpose of this application is to solve or at least alleviate some of the problems existing in the prior art.

[0009] A first aspect of this application is to provide a method for operating an engine that uses natural gas as fuel and is equipped with a natural gas tank. In this method, a refueling event of the engine's natural gas tank is detected; if a refueling event is detected, a knock protection mode of the engine is activated.

[0010] Compared to existing technologies, this invention does not passively implement knock protection measures only after engine knocking is detected. Instead, it proactively activates the engine's knock protection mode upon detecting a natural gas refueling event in the engine's gas tank. This is because the inventors discovered that newly added natural gas may have a lower octane rating than the remaining natural gas in the tank, making the engine more prone to knocking when mixed with natural gas for engine fuel supply. Therefore, by proactively activating the engine's knock protection mode upon detecting a natural gas refueling event before engine operation, the invention ensures safe and reliable operation of the engine after startup, preventing or at least eliminating severe knocking.

[0011] Furthermore, when a refueling event is detected in the engine's natural gas tank, there is no need to test the quality of the newly refueled natural gas, nor is there a need to test the quality of the mixture obtained by mixing the newly refueled natural gas with the remaining natural gas in the natural gas tank. This allows for the implementation of knock protection measures in advance in a very simple way, preventing the engine from knocking or at least preventing severe knocking.

[0012] A second aspect of this application is to provide an engine system configured to implement the steps of the method of operating the engine.

[0013] A third aspect of this application is to provide a controller including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method of operating an engine.

[0014] A fourth aspect of this application is to provide a computer-readable storage medium on which a computer program is stored, the computer program being executed by a processor to implement the steps of the method for operating an engine.

[0015] A fifth aspect of this application is to provide a program product comprising a computer program, characterized in that, when the computer program is executed by a processor, it implements the steps of the method for operating the engine. Attached Figure Description

[0016] The embodiments of this application will be described in further detail below with reference to the accompanying drawings. However, those skilled in the art will understand that these drawings are for illustrative purposes only and should not be construed as limiting the scope of this application. The accompanying drawings show:

[0017] Figure 1 This is a block diagram of an engine system according to one embodiment of this application; and

[0018] Figure 2 This is a flowchart of a method for operating an engine according to one embodiment of this application. Detailed Implementation

[0019] Figure 1A block diagram of an engine system according to one embodiment of this application is shown. The engine system has an engine 10 as a core component, which operates using natural gas as fuel and is therefore associated with a natural gas tank 17 storing liquefied natural gas as fuel. Exhaust gas produced by the engine 10 is discharged through an exhaust pipe 11, and fresh air enters a mixer 16 through an intake pipe 14 via a throttle valve 15 and is mixed with the natural gas from the natural gas tank 17 before being supplied to the engine 10. To improve the performance of the engine 10, the engine system may also have a turbocharger 12, such as an exhaust gas turbocharger, which uses the exhaust gas from the exhaust pipe 11 to increase the pressure of the fresh air in the intake pipe 14, thereby increasing the intake volume of the engine 10 and thus increasing the output power and torque of the engine 10. Here, a turbocharger control valve 13 is provided for the turbocharger 12, which can regulate the exhaust gas flow rate entering the turbocharger 12, thereby controlling the boost pressure of the turbocharger 12. Here, a filling event sensor 18 is provided for the natural gas tank 17, which is used to detect filling events of the natural gas tank 17 of the engine 10. Here, the filling event sensor 18 can be, for example, a level sensor and / or a pressure sensor. During the filling process of the natural gas tank 17, the liquid level and internal pressure of the natural gas tank 17 will increase. Therefore, the filling event of the natural gas tank 17 can be detected by detecting the liquid level of the natural gas tank 17 by the level sensor and / or by detecting the internal pressure of the natural gas tank 17 by the pressure sensor. The engine system also has a knock sensor 20 for detecting whether knocking occurs in the engine 10. Figure 1 In the illustrated embodiment, two knock sensors 20 are shown. However, depending on the number of cylinders in the engine, a different number of knock sensors 20 may be used; for example, one knock sensor 20 may be provided for each cylinder. However, this is not mandatory, and in the simplest case, only one knock sensor 20 may be provided. The engine system also has an ignition system 21 configured to ignite the air-fuel mixture supplied to the engine 10. Finally, the engine system also includes a controller 19. Figure 1 As shown, the controller 19 is signal-connected to the refueling event sensor 18, the knock sensor 20, the ignition system 21, the throttle valve 15, and the turbocharger control valve 13 (shown by dashed lines in the figure) to receive corresponding sensor signals, analyze and process the sensor signals, and control the corresponding actuators based on the analysis and processing results of the sensor signals.

[0020] Figure 2 A flowchart of a method for operating an engine according to one embodiment of this application is shown. The following will use... Figure 2 This application describes a method for operating an engine according to one embodiment.

[0021] The method begins in step S100. After the method begins, a refueling event of the natural gas tank 17 of the engine 10 is first detected in step S110. This refueling event can be detected by the refueling event sensor 18. As described above, the refueling event sensor 18 can be, for example, a level sensor and / or a pressure sensor, thereby detecting the refueling event of the natural gas tank 17 by detecting the level of the natural gas tank 17 by the level sensor and / or by detecting the internal pressure of the natural gas tank 17 by the pressure sensor.

[0022] Next, in step S120, it is determined whether the refueling event has been detected. If the increase in the liquid level of the natural gas tank 17 exceeds a preset first threshold and / or if the increase in the internal pressure of the natural gas tank 17 exceeds a preset second threshold, then the refueling event is detected.

[0023] If the refueling event is detected in step S120, the knock protection mode of the engine 10 is activated in step S130. Otherwise, the process returns to step S110 to re-detect the refueling event of the natural gas tank 17 of the engine 10.

[0024] After activating the knock protection mode of the engine 10 in step S130, if the engine 10 is detected to be running in step S140, the load of the engine 10 is detected in step S150.

[0025] Typically, the engine is prone to knocking in the medium-to-high load range, while knocking does not occur in the low load range. Within the scope of this application, the medium-to-high load range where knocking is prone to occur is referred to as the knocking region. Here, the load of the engine 10 can be detected, for example, by detecting the opening of the throttle valve 15 of the engine 10. When the opening of the throttle valve 15 of the engine 10 is above a first preset value (including the first preset value), for example, above 70%, the engine 10 is in the medium-to-high load range, that is, in the knocking region. Correspondingly, when the opening of the throttle valve 15 of the engine 10 is below the first preset value (excluding the first preset value), for example, below 70%, the engine 10 is in the low load range, that is, not in the knocking region.

[0026] Therefore, in step S160, it is determined, for example, whether the engine 10 is in the knock zone based on the load of the engine 10. If the engine 10 is in the knock zone, then in step S170, the ignition system 21 of the engine 10 is corrected by reducing the ignition advance angle and the engine 10 is torque-limited.

[0027] In other words, although the knock protection mode is activated, measures to reduce the knock tendency are not actually taken as long as the engine is not in the knock zone. Measures to reduce the knock tendency are only taken when the engine is in the knock zone. For example, the knock tendency can be reduced by decreasing the ignition advance angle and limiting torque.

[0028] Here, the ignition advance angle reduction correction can, for example, reduce the ignition advance angle by a second preset value, preferably 6° crankshaft angle, and the torque limitation can, for example, limit the torque of the engine 10 to a third preset value, preferably 70%, of the rated torque of the engine 10.

[0029] Therefore, measures to reduce the tendency to knock are not passively taken only after a knock occurs, but rather measures to reduce the tendency to knock are actively taken as soon as a refueling event of the natural gas tank is detected and the engine is in the knock zone, thereby avoiding severe knocking and damage to the engine.

[0030] In the next step S180, it is detected whether the engine 10 has experienced knocking. This can be done, for example, by using a knock sensor 20. If knocking is detected in step S180, the current ignition advance angle reduction correction is maintained in step S190, and the torque limitation is gradually released in predetermined first-step increments until the torque limitation is completely released in step S210. Then, in step S220, the knock protection mode is exited, and the method ends in step S300.

[0031] Conversely, if no knocking is detected in the engine 10 in step S180, the ignition advance angle reduction correction is gradually released in step S200 with a pre-set second step size, and the torque limitation is gradually released with a pre-set third step size. Here, the first step size is smaller than the third step size. Therefore, the torque limitation is released at a faster speed in step S200, and at a slower speed in step S190.

[0032] Next, during the gradual release of the ignition advance angle reduction correction with the second step size in step S200, it is determined in step S230 whether the ignition advance angle reduction correction has returned to zero. If it is determined in step S230 that the ignition advance angle reduction correction has returned to zero, then in step S210, it is detected whether the torque limit has been completely released. When it is detected in step S210 that the torque limit has been completely released, the knock protection mode is exited in step S220, and then the method is terminated in step S300.

[0033] If it is determined in step S230 that the ignition advance angle reduction correction has not yet returned to zero, the process returns to step S180 to detect whether engine 10 has experienced knocking. If engine 10 knocking is detected in step S180, the current ignition advance angle reduction correction is maintained in step S190, that is, the further release of the ignition advance angle reduction correction is stopped. When the torque limit is detected to be completely released in step S210, the knock protection mode is exited in step S220, and then the method ends in step S300. If engine 10 knocking is not detected in step S180, the method continues in step S200.

[0034] When the ignition timing reduction correction and torque limiting are released to a certain extent, the engine may become prone to knocking again. At this point, the ignition timing reduction correction is no longer released; instead, the current ignition timing reduction correction is maintained, but the torque limiting is continued to be released until the torque limiting is completely released, at which point the knock protection mode is exited. Because the ignition timing reduction correction and torque limiting are released gradually, although knocking is detected at this point, it is only a very slight knocking.

[0035] This not only avoids the strong knocking under high load caused by using low-octane natural gas in the engine, but also gradually removes torque limiting according to different knocking conditions, ensuring engine power; and gradually removes ignition advance angle reduction correction according to different knocking conditions, preventing excessive ignition advance angle correction for relatively high-octane natural gas, thus ensuring engine fuel economy.

[0036] It should be noted that the above method can be, for example, through... Figure 1 The controller 19 shown is used to implement the method. The controller 19 includes a memory, a processor, and a computer program stored in the memory. The processor executes the computer program to implement the steps of the method.

[0037] This application also relates to a computer-readable storage medium on which a computer program is stored, which, when executed by a processor, implements the steps of the method.

[0038] This application also relates to a program product comprising a computer program that, when executed by a processor, implements the steps of the method.

[0039] The above descriptions are merely exemplary embodiments of this application. The scope of protection of this application is not limited to the above embodiments, and all technical solutions falling within the concept of this application are within the scope of protection of this application. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of this application should also be considered within the scope of protection of this application.

Claims

1. A method of operating an engine (10), said engine (10) being fueled by natural gas and equipped with a natural gas tank (17), Its features are, Detect the refueling event of the natural gas tank (17) of the engine (10); If a refueling event of the natural gas tank (17) is detected, the knock protection mode of the engine (10) is activated.

2. The method according to claim 1, characterized in that, The refueling event is detected in the following ways: The liquid level of the natural gas tank (17) is detected. If the amount or rate of increase of the liquid level of the natural gas tank (17) exceeds a preset first threshold, the filling event is detected. And / or The internal pressure of the natural gas tank (17) is detected. If the increase in the internal pressure of the natural gas tank (17) or the rate of increase exceeds a preset second threshold, the refueling event is detected.

3. The method according to claim 1, characterized in that, In the knock protection mode, after starting the engine (10), the load of the engine (10) is detected and it is determined whether the engine (10) is in the knock zone based on the load of the engine (10). If the engine (10) is in the knock zone, the ignition system (21) of the engine (10) is corrected by reducing the ignition advance angle and the engine (10) is torque limited.

4. The method according to claim 3, characterized in that, The load of the engine (10) is detected by detecting the opening of the throttle valve (15) of the engine (10). When the opening of the throttle valve (15) of the engine (10) is above a first preset value, preferably above 70%, the engine (10) is in the knock zone.

5. The method according to claim 3, characterized in that, If the engine (10) is in the knock zone, the ignition advance angle is reduced by a second preset value, preferably 6° crankshaft angle, and the torque of the engine (10) is limited to a third preset value, preferably 70%, of the rated torque of the engine (10).

6. The method according to claim 3, characterized in that, Detect whether the engine (10) has experienced knocking; If knocking is detected in the engine (10), the current ignition advance angle reduction correction is maintained, and the torque limit is gradually released in a preset first step length until the torque limit is completely released and the knocking protection mode is exited. If no knocking is detected in the engine (10), the ignition advance angle reduction correction is gradually released in a pre-set second step, and the torque limitation is gradually released in a pre-set third step. The length of the first step is less than the length of the third step.

7. The method according to claim 6, characterized in that, When gradually removing the ignition advance angle reduction correction with the second step size, it is determined whether the ignition advance angle reduction correction returns to zero; If the ignition advance angle reduction correction has been reduced to zero, the knock protection mode will be exited when the torque limit is completely released. If the ignition advance angle reduction correction has not yet returned to zero, the engine (10) is checked for knocking. If knocking is detected in the engine (10), the ignition advance angle reduction correction is stopped from being released, and the knocking protection mode is exited when the torque limit is completely released.

8. An engine system, characterized in that, The engine system is configured to implement the steps of the method according to any one of claims 1 to 7.

9. The engine system according to claim 8, characterized in that, The engine system includes: Engine (10); Natural gas tank (17); A refueling event sensor (18) is used to detect refueling events of the natural gas tank (17) of the engine (10); and A knock sensor (20) is used to detect whether the engine (10) is knocking.

10. The engine system according to claim 9, characterized in that, The filling event sensor (18) is a level sensor and / or a pressure sensor.

11. A controller comprising a memory, a processor, and a computer program stored in the memory, characterized in that, The processor executes the computer program to implement the steps of the method according to any one of claims 1 to 7.

12. A program product comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 7.

Images