Multi-fuel engine system and control method thereof

Abstract

One aspect of the present disclosure provides a method for controlling a multi-fuel engine system configured to use gaseous fuel and hydrogen, in which a maximum pressure and a combustion center of a cylinder may be detected while the multi-fuel engine system is operating, and a ratio of hydrogen to be mixed with the gaseous fuel may be determined based on the detected maximum pressure in the cylinder and the combustion center.

Description

Technical Field

[0001] Cross-references to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2023-0052949, filed with the Korean Intellectual Property Office on April 21, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to a multifuel engine system and its control method, and more specifically, to a multifuel engine system and its control method capable of reducing greenhouse gas emissions by adjusting the proportion of environmentally friendly fuels (e.g., hydrogen) through adjusting the EGR rate. Background Technology

[0004] Dual-fuel engine systems are configured to selectively or simultaneously use liquid fuels (such as diesel) and gaseous fuels (such as natural gas). Dual-fuel engine systems can meet both economic and environmental requirements.

[0005] The dual-fuel engine system has a gas fuel operating mode that uses gaseous fuel and a liquid fuel operating mode that uses liquid fuel.

[0006] Liquid fuel is injected into the combustion chamber through main injectors located in each cylinder head; while gaseous fuel is distributed from the main supply pipe to the distribution pipe for each cylinder, and then injected into the intake port of the cylinder head through the intake valve (GAV).

[0007] Dual-fuel engine systems feature micro-ignition injectors for igniting gaseous fuels. Because dual-fuel engine systems are based on diesel engines, which compress intake air under high temperature and pressure to achieve auto-ignition, unlike gasoline engines that ignite fuel via spark plugs. Gaseous fuels such as natural gas have low flash points but high auto-ignition temperatures of approximately 550°C. Therefore, in gaseous fuel operating mode, a small amount of ignition fuel (e.g., diesel) is injected immediately before the main gaseous fuel injection (main injection process) to induce ignition. This allows for stable ignition of the gaseous fuel. Furthermore, even in liquid fuel operating mode, a small amount of ignition fuel (e.g., diesel) is injected immediately before the liquid fuel injection. This improves the combustion environment in the combustion chamber, thereby improving NOx and combustion performance.

[0008] However, dual-fuel engine systems have limitations in fully meeting greenhouse gas emission regulations, which are only strengthened by using gaseous and / or liquid fuels.

[0009] The matters described in the background art are for ease of explanation and may include matters outside the prior art that are well known to those skilled in the art. Summary of the Invention

[0010] Technical issues

[0011] This disclosure is proposed in consideration of the foregoing description. One aspect of this disclosure provides a multi-engine system and its control method capable of adjusting the proportion of environmentally friendly fuels and EGR rate to reduce greenhouse gas emissions.

[0012] The problem to be solved in the embodiments is not limited to this. It may include the purpose and effect understood from the means or embodiments used to solve the problem.

[0013] Technical solution

[0014] To achieve the above objectives, one aspect of this disclosure provides a method for controlling a multi-fuel engine system configured to use gaseous fuel and hydrogen, wherein the maximum pressure of the cylinder and the combustion center can be detected during operation of the multi-fuel engine system, and the proportion of hydrogen to be mixed with the gaseous fuel can be determined based on the detected maximum pressure of the cylinder and the detected combustion center.

[0015] According to one embodiment, the controller can determine whether conditions permitting the mixing of hydrogen with gaseous fuel are met during the operation of a multi-fuel engine system, and determine the proportion of hydrogen to be mixed with gaseous fuel based on whether the conditions permitting the mixing of hydrogen with gaseous fuel are met.

[0016] According to one embodiment, the conditions that allow hydrogen to be mixed with gaseous fuel may be that the maximum pressure of the cylinder detected is at most the design pressure of the cylinder and the combustion center detected is at least the set combustion center.

[0017] According to one embodiment, when the conditions that allow hydrogen to be mixed with gaseous fuel are met, the proportion of hydrogen can be increased to maintain at most a set proportion.

[0018] According to one embodiment, after increasing the proportion of hydrogen, it can be re-determined whether the conditions for allowing hydrogen to be mixed with gaseous fuel are met, and if the conditions for allowing hydrogen to be mixed with gaseous fuel are not met, the proportion of hydrogen can be reduced to the proportion of hydrogen before the increase.

[0019] According to one embodiment, the controller can detect EGR during the operation of a multi-fuel engine system, increase the EGR rate to maintain at most a set EGR rate, and increase the proportion of hydrogen based on the increased EGR rate.

[0020] According to one embodiment, when the conditions for allowing the mixing of hydrogen and gaseous fuel are not met, the EGR rate can be increased to maintain at most the set EGR rate, and after increasing the EGR rate, it can be re-determined whether the conditions for allowing the mixing of hydrogen and gaseous fuel are met.

[0021] According to one embodiment, after increasing the EGR rate, when the conditions allowing hydrogen to be mixed with gaseous fuels are met, the proportion of hydrogen can be increased based on the increased EGR rate to maintain at most a set proportion.

[0022] According to one embodiment, after increasing the EGR rate, if the conditions allowing hydrogen to be mixed with gaseous fuels are not met, the EGR rate can be reduced to the EGR rate before the increase.

[0023] According to one embodiment, after increasing the EGR rate, when the conditions allowing hydrogen to mix with gaseous fuel are met, the turbine inlet temperature of the turbocharger can be at most a set temperature. When the turbine inlet temperature is at most the set temperature, the proportion of hydrogen can be increased based on the increased EGR rate to maintain at most the set proportion. And when the turbine inlet temperature exceeds the set temperature, the EGR rate can be reduced to the EGR rate before the EGR rate was reduced.

[0024] According to one embodiment, a multi-fuel engine system may include: a cylinder including a combustion chamber, an intake port communicating with the combustion chamber, and an exhaust port communicating with the combustion chamber; a gas inflow valve configured to inject at least one of gaseous fuel or a mixture of gaseous fuel and hydrogen into the intake port; and a controller configured to determine the proportion of hydrogen to be mixed with the gaseous fuel based on the maximum pressure of the cylinder and the combustion center of the cylinder.

[0025] According to one embodiment, the multi-fuel engine system may further include: a gaseous fuel supply source fluidly connected to a gas inlet valve via a gaseous fuel supply pipe; a gaseous fuel control valve disposed in the gaseous fuel supply pipe; a hydrogen supply source fluidly connected to the gas inlet valve via a hydrogen supply pipe; and a hydrogen control valve disposed in the hydrogen supply pipe. The controller may be configured to control the flow rate control valves in the gaseous fuel supply pipe and the hydrogen supply pipe.

[0026] The gas fuel supply line and the hydrogen supply line can be connected to each other in the main supply line, and the main supply line can be connected to the gas inlet valve.

[0027] The controller can be configured to detect the EGR rate during operation of the multi-fuel engine system, increase the EGR rate to maintain at most a set EGR rate, and increase the proportion of hydrogen based on the increased EGR rate.

[0028] The controller can be configured to determine whether conditions permitting the mixing of hydrogen with gaseous fuels are met during operation of a multi-fuel engine system, and to determine the proportion of hydrogen to be mixed with gaseous fuels based on whether the conditions permitting the mixing of hydrogen with gaseous fuels are met.

[0029] Beneficial effects

[0030] According to this disclosure, a multi-fuel engine system can be operated using a mixture of gaseous fuel and environmentally friendly fuel (decarbonized fuel), thereby reducing greenhouse gas (nitrogen or methane) emissions.

[0031] Specifically, the ratio of hydrogen to gaseous fuel can be optimally set based on maximum pressure, combustion center, and EGR rate, thereby reducing the maximum internal pressure of the cylinder and relatively slowing down the combustion rate (combustion center). Therefore, emissions of greenhouse gases (nitrogen oxides or methane) can be reduced.

[0032] According to this disclosure, the EGR rate can be increased to maintain at most a set EGR rate, and the proportion of hydrogen can be increased to maintain at most a set hydrogen proportion, thereby improving the combustion efficiency of the multifuel engine system and rapidly reducing greenhouse gas (nitrogen oxides or methane) emissions. Attached Figure Description

[0033] Figure 1 This is a view illustrating a multi-fuel engine system according to an embodiment of the present disclosure;

[0034] Figure 2 This is a view illustrating a method for controlling a multi-fuel engine system according to an embodiment of the present disclosure;

[0035] Figure 3 This is a view that illustrates in detail a method for controlling a multi-fuel engine system according to embodiments of the present disclosure;

[0036] Figure 4 It is a view showing that the detected combustion center is at least a set combustion center; and

[0037] Figure 5 This is a view showing the maximum detected pressure of the cylinder up to the cylinder's set pressure. Detailed Implementation

[0038] Some embodiments of this disclosure will now be described in detail with reference to the exemplary accompanying drawings. In the following description, even if elements are shown in different drawings, the same reference numerals will be assigned to the same parts. Furthermore, detailed descriptions of well-known features or functions will be omitted in the following description to avoid unnecessarily obscuring the spirit of this disclosure.

[0039] Additionally, in the following description of components according to embodiments of the present disclosure, the terms “first,” “second,” “A,” “B,” “(a),” and “(b)” may be used. These terms are intended only to distinguish one component from another, and they do not limit the nature, order, or sequence of the constituent components.

[0040] According to embodiments of this disclosure, singular terms are also intended to include plural forms unless the context explicitly indicates otherwise. When at least one (or one or more) of “A”, “B”, and “C” is mandated, at least one (or one or more) of “A”, “B”, and “C” can include at least one of all combinations of “A”, “B”, or “C”.

[0041] Additionally, when a component is described as "connected," "coupled," or "connected" to another component, that component may be directly "connected," "coupled," or "connected" to that other component, or that component may be "connected," "coupled," or "connected" to that other component through another component located between that component and that other component.

[0042] Additionally, when the specification describes a component as being formed or disposed "above" or "below" each component, the expression "above" or "below" means that two components are in direct contact with each other, or that at least one different component is formed or disposed between two components. Furthermore, the expression "above" or "below" can include both upward and downward directions from a component.

[0043] Unless otherwise defined, all terms used herein (including technical or scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Terms such as those defined in common dictionaries shall be interpreted as having the same meaning as in the context of the relevant technical field, and shall not be interpreted as having an ideal or over-regular meaning unless expressly defined in this application.

[0044] Reference Figure 1 A multi-fuel engine system 10 according to an embodiment of the present disclosure may include at least one cylinder 11 having a combustion chamber 13. The cylinder 11 may have a combustion chamber 13 defined therein, and a piston 19 may be configured to reciprocate within the combustion chamber 13. The cylinder 11 may have an intake port 12 communicating with the combustion chamber 13 and an exhaust port 14 communicating with the combustion chamber 13. An intake valve 15 may be configured to open and close the intake port 12, and an exhaust valve 16 may be configured to open and close the exhaust port 14.

[0045] The intake pipe 17 and intake manifold (not shown) can be connected to the intake port 12, and intake air can be introduced into the intake port 12 through the intake pipe 17 and intake manifold. When the intake valve 15 is open, intake air can be introduced into the combustion chamber 13 through the intake port 12.

[0046] Exhaust pipe 18 and exhaust manifold (not shown) can be connected to exhaust port 14, and exhaust gas can be discharged to exhaust pipe 18 through exhaust port 14 and exhaust manifold. When exhaust valve 16 is open, exhaust gas can be discharged from combustion chamber 13 through exhaust port 14.

[0047] Reference Figure 1 According to embodiments of the present disclosure, a multi-fuel engine system 10 may include a main injector 21 disposed on a combustion chamber 13, an ignition injector 22 spaced apart from the main injector 21, and a gas inflow valve 23 mounted on an air inlet 12.

[0048] The main injector 21 can be configured to inject liquid fuel into the combustion chamber 13. The main injector 21 can be connected to the liquid fuel supply source 31 via a common rail or pump fluid connection. For example, the liquid fuel can be diesel fuel.

[0049] The ignition injector 22 can be configured to inject ignition fuel into the combustion chamber 13. According to one embodiment, the ignition fuel can be a liquid fuel such as diesel. The ignition injector 22 can be connected to the liquid fuel supply source 31 via a common rail or pump fluid connection.

[0050] The gas inlet valve 23 can be configured to inject at least one of gaseous fuel or a mixture of gaseous fuel and hydrogen into the inlet 12. Specifically, the gas inlet valve 23 can be located on the inlet 12, upstream of the inlet valve 15. For example, the liquid fuel can be natural gas.

[0051] Gaseous fuel supply source 32 and hydrogen supply source 33 can be fluidly connected to gas inlet valve 23. Gaseous fuel can be supplied from gaseous fuel supply source 32 to gas inlet valve 23, and hydrogen can be supplied from hydrogen supply source 33 to gas inlet valve 23. When the flow rate of supplied hydrogen is determined, the flow rate of supplied gaseous fuel can be adjusted relatively. Therefore, the ratio of mixed gaseous fuel and hydrogen can be determined. In particular, when the proportion of hydrogen as a decarbonized fuel is relatively increased, greenhouse gas emissions can be minimized by fully burning unburned greenhouse gases in combustion chamber 13.

[0052] The gas fuel supply source 32 can be fluidly connected to the gas inlet valve 23 via the gas fuel supply pipe 32a. Pressure control valves, gas fuel control valves 32b, on / off valves, or various sensors can be installed in the gas fuel supply pipe 32a.

[0053] The hydrogen fuel supply source 33 can be fluidly connected to the gas inlet valve 23 via the hydrogen supply pipe 33a. Pressure control valves, hydrogen control valves 33b, on / off valves, or various sensors can be installed in the hydrogen supply pipe 33a.

[0054] When the hydrogen control valve 33b controls the flow rate of supplied hydrogen, the gas fuel control valve 32b can relatively control the flow rate of supplied gas fuel. Therefore, the ratio of mixed gas fuel and hydrogen can be determined.

[0055] The gaseous fuel supply pipe 32a and the hydrogen supply pipe 33a can be fluidly connected to the gas inlet valve 23 via the main supply pipe 35. Specifically, the gaseous fuel supply pipe 32a and the hydrogen supply pipe 33a can be joined to each other at the first end (inlet) of the main supply pipe 35, and the second end (outlet) of the main supply pipe 35 can be connected to the gas inlet valve 23. Therefore, the gaseous fuel supplied through the gaseous fuel supply pipe 32a and the hydrogen supplied through the hydrogen supply pipe 33a can be mixed in a specific ratio in the main supply pipe 35.

[0056] Reference Figure 1 The multi-fuel engine system 10 according to embodiments of the present disclosure may include a turbocharger 25 disposed between an intake manifold 17 and an exhaust manifold 18 in communication with both the intake manifold 17 and the exhaust manifold 18. The turbocharger 25 may include: a compressor 26 for compressing outside air introduced through the intake manifold 17; a turbine 27 rotated by exhaust gas discharged through the exhaust manifold 18; and a common shaft 28 for coupling the compressor 26 to the turbine 27. A boost air cooler 29 may be disposed on the intake manifold 17, downstream of the compressor 26.

[0057] Reference Figure 1 The multi-fuel engine system 10 according to embodiments of the present disclosure may include an exhaust gas recirculation system 40 to recirculate a portion of the exhaust gas discharged from the exhaust port 14 toward the intake port 12.

[0058] The exhaust gas recirculation system 40 may include: an EGR (exhaust gas recirculation) duct 41 disposed between the exhaust pipe 18 and the intake pipe 17; and an EGR cooler 42 disposed in the EGR duct 41 to recirculate exhaust gas to mix with fresh air.

[0059] according to Figure 1 In one embodiment, the inlet of the EGR duct 41 can be connected to the exhaust pipe 18 at a point downstream of the turbine 27, and the outlet of the EGR duct 41 can be connected to the intake pipe 17 at a point upstream of the compressor 26, so that the EGR duct 41 forms a low-pressure EGR path.

[0060] EGR cooler 42 can be configured to cool EGR gas passing through EGR conduit 41. An on / off valve 43 can be located upstream of EGR cooler 42. When on / off valve 43 is open, EGR gas can pass through EGR conduit 41, and when on / off valve 43 is closed, EGR gas cannot pass through EGR conduit 41. EGR valve 44 can be located downstream of EGR cooler 42, and EGR valve 44 can be configured to control the flow rate of EGR gas discharged from EGR cooler 42.

[0061] The EGR rate can be calculated using the CO2 concentration measured by an exhaust gas analyzer. The exhaust gas analyzer measures the exhaust-side CO2 concentration (CO2) at point 18a downstream of the turbine 27 of the turbocharger 25. e ), and can measure the intake-side CO2 concentration (CO2 concentration) at point 17a upstream of the compressor 26 of the turbocharger 25. i When the exhaust gas is no longer recirculated, the atmospheric CO2 concentration (CO2) can be measured at point 17a upstream of compressor 26. amb CO2 concentration can be measured in vol% and the EGR rate can be calculated using the following equation (1).

[0062] Equation 1

[0063]

[0064] The controller 100 can be configured to control the operation of the intake valve 15, exhaust valve 16, gas fuel control valve 32b, hydrogen control valve 33b, main injector 21, ignition injector 22 and gas inflow valve 23 based on various fuel modes.

[0065] According to one embodiment, the controller 100 can be configured to detect the maximum pressure (P) of the cylinder 11 using various sensors when the multi-fuel engine system 10 is operating using liquid or gaseous fuel. m The controller 100 determines the proportion (R) of hydrogen to be mixed with gaseous fuel based on the detected internal pressure (P) of cylinder 11, the combustion center time (COC), and the EGR rate (E). The combustion center (COC) can be the point in time when half of the fuel supplied to cylinder 11 is completely burned. The controller 100 can control the proportion of hydrogen and the proportion of gaseous fuel by controlling the hydrogen control valve 33b and the gaseous fuel control valve 32b. Therefore, the mixing ratio of gaseous fuel and hydrogen can be determined.

[0066] Figure 2 This is a view illustrating a method for controlling a multifuel engine system according to an embodiment of the present disclosure.

[0067] Reference Figure 2 Liquid or gaseous fuel is supplied to the combustion chamber 13 of cylinder 11 and burned to operate the multi-fuel engine system 10 (S1).

[0068] In liquid fuel mode, when air is introduced into intake port 12 and intake valve 15 is opened, air is introduced into combustion chamber 13 of cylinder 11, and then intake valve 15 is closed. When piston 19 moves upward to top dead center, the air introduced into combustion chamber 13 is compressed. Subsequently, main injector 21 injects liquid fuel into combustion chamber 13, causing the liquid fuel to burn through compression ignition.

[0069] In gas fuel mode, when air is introduced into the intake port 12, the gas inlet valve 23 injects gaseous fuel into the intake port 12, and when the intake valve 15 is opened, air and gaseous fuel are introduced into the combustion chamber 13, and then the intake valve 15 is closed. When the piston 19 moves upward to top dead center, the gaseous fuel and air introduced into the combustion chamber 13 are compressed. Subsequently, the ignition injector 22 injects ignition fuel into the combustion chamber 13, causing the gaseous fuel to be ignited and burned in the combustion chamber 13.

[0070] When the multi-fuel engine system 10 is running using liquid or gaseous fuel, the controller 100 uses various sensors to detect the maximum pressure (P) of the cylinder 11. m ), combustion center (COC) and EGR rate (E) (S2). The combustion center (COC) can be the point at which half of the fuel supplied to cylinder 11 is completely burned.

[0071] The controller 100 determines the proportion (R) of hydrogen to be mixed with gaseous fuel based on the detected internal pressure P, combustion center (COC), and EGR rate (E) of the cylinder 11 (S3). When the hydrogen control valve 33b is controlled to a specific opening, the hydrogen proportion (R) is determined, and based on the determined hydrogen proportion, the gaseous fuel proportion is determined relative to the gaseous fuel control valve 32b, thereby determining the volume ratio of gaseous fuel and hydrogen for mixing. For example, when the hydrogen proportion is determined to be 5 vol%, the gaseous fuel proportion can be determined to be 95 vol%.

[0072] According to one embodiment, in S3, the EGR rate (E) can be relatively increased to maintain at most a set EGR rate (E). t The controller 100 can control the EGR valve 44 to relatively increase the opening degree of the EGR valve 44, thereby relatively increasing the EGR rate (E).

[0073] The controller 100 operates the multi-fuel engine system 10 (S4) using a mixture of gaseous fuel and hydrogen. Air is introduced into the intake port 12, the gas inlet valve 23 injects the mixture of gaseous fuel and hydrogen into the intake port 12, and the intake valve 15 is opened, allowing the mixture of gaseous fuel and hydrogen, along with air, to be introduced into the combustion chamber 13. The intake valve 15 is then closed. When the piston 19 moves to top dead center, the mixture of gaseous fuel and hydrogen, along with air, introduced into the combustion chamber 13 is compressed. The ignition injector 22 injects ignition fuel into the combustion chamber 13, causing the mixture of gaseous fuel and hydrogen to ignite and burn within the combustion chamber 13.

[0074] Figure 3 This is a view that illustrates in detail a method for controlling a multifuel engine system according to embodiments of the present disclosure.

[0075] Liquid or gaseous fuel is supplied to the combustion chamber 13 of cylinder 11 and burned to operate the multi-fuel engine system 10 (S11).

[0076] During operation of the multi-fuel engine system 10, the controller 100 can determine whether conditions are met that allow hydrogen to be mixed with gaseous fuel (or whether the proportion of hydrogen to be mixed with gaseous fuel is a permissible proportion). According to one embodiment, the gaseous fuel can be, for example, natural gas, and the hydrogen can be hydrogen gas. Hydrogen has a high flame velocity. Therefore, when the mixture of hydrogen (hydrogen gas) and gaseous fuel (gaseous fuel) burns in the combustion chamber 13 of the cylinder 11, the combustion rate and center of combustion (COC) are relatively fast. Therefore, the maximum pressure (P) of the cylinder 11 can be relatively increased. m Specifically, when the proportion (R) of hydrogen (hydrogen gas) exceeds a set proportion (R... t When the combustion center (COC) is smaller than the set combustion center (COC), the combustion center (COC) will be smaller. t (The combustion center becomes earlier than the set combustion center time). Therefore, the maximum pressure of cylinder 11 (P) m This will exceed the design pressure (P) of cylinder 11. d Therefore, the detected maximum pressure of cylinder 11 is compared with the design pressure (Pd) of cylinder 11, and the detected combustion center (COC) is compared with the set combustion center (COC). t This is compared to determine whether the conditions for allowing hydrogen to be mixed with gaseous fuels are met. The set combustion center (COC) is... t () can be the combustion center detected when the multi-fuel engine system 10 is running without hydrogen supply.

[0077] Specifically, the condition that allows hydrogen to be mixed with gaseous fuel can be the detected maximum pressure (P) of cylinder 11. mAt most the design pressure of cylinder 11 (P) d And the detected combustion center (COC) is at least the set combustion center (COC). t ) conditions.

[0078] Reference Figure 3 The controller 100 can determine whether the detected maximum pressure (Pm) of the cylinder 11 is at most the design pressure (Pd) of the cylinder 11 (see [reference]). Figure 4 ), and by determining whether the detected combustion center (COC) is at least the set combustion center (COC) t (See also) Figure 5 (S12) is used to determine whether the conditions for allowing hydrogen to be mixed with gaseous fuels are met.

[0079] In S12, when the maximum pressure (P) of the detected cylinder 11 is determined... m At most the design pressure of cylinder 11 (P) d And the detected combustion center (COC) is at least the set combustion center (COC). t When the controller 100 determines that the conditions allowing hydrogen to be mixed with gaseous fuel are met, the proportion of hydrogen (R) increases by a specific value (a vol%) (S13). Under operating conditions where the multi-fuel engine system 10 operates using only liquid or gaseous fuel, since no hydrogen is added, the proportion of hydrogen to be mixed with the gaseous fuel (R) can be 0 vol%, and the proportion of hydrogen (R) can gradually increase from 0 vol% to a specific value (a vol%).

[0080] After the proportion of hydrogen (R) in S13 is increased by a specific value (a vol%), the controller 100 can re-determine whether the conditions allowing hydrogen to be mixed with gaseous fuel are met. Specifically, the controller 100 can re-determine the detected maximum pressure (P) of cylinder 11. m Is it at most the design pressure (P) of cylinder 11? d And whether the detected combustion center (COC) is at least the set combustion center (COC) t (S14) to reassess whether the conditions for allowing the mixing of hydrogen with gaseous fuels are met.

[0081] When the maximum pressure (P) of cylinder 11 is determined in S14 m ) Exceeds the design pressure of cylinder 11 (P) d And the detected combustion center (COC) is smaller than the set combustion center (COC) value. tWhen the hydrogen ratio (R) is not determined to meet the conditions allowing the mixing of hydrogen and gaseous fuel, the controller 100 may subtract a specific value (a vol%) from the hydrogen ratio (R) (S14-1). In other words, when the hydrogen ratio (R) is subtracted from the specific value (a vol%), the hydrogen ratio (R) decreases to the hydrogen ratio before the addition in S12 (i.e., the hydrogen ratio detected in S12). Thereafter, the controller 100 determines whether the detected EGR rate (E) is at most the set EGR rate (E). t (S15). Less than the set combustion center (COC) t The combustion center (COC) refers to the time before combustion center (COC) being earlier than the set combustion center time (COC). t When the center of combustion (COC) is smaller than the set center of combustion (COC) t At that time, as the combustion center (COC) arrives relatively early, the maximum pressure (P) of cylinder 11 is... m This will exceed the design pressure (P) of cylinder 11. d When the maximum pressure of cylinder 11 (P) m ) Exceeds the design pressure of cylinder 11 (P) d When mixing with gaseous fuels, the proportion of hydrogen to be mixed with the gaseous fuel will not increase relatively.

[0082] Set EGR rate (E t The set EGR rate can be a reference EGR rate used to determine whether combustion in the multi-fuel engine system 10 is performing stably. t Various settings can be made according to the specifications and operating conditions of the multi-fuel engine system 10. The EGR rate (E) is at most the set EGR rate (E...). t When the EGR rate (E) exceeds the set EGR rate (E), the combustion in the multi-fuel engine system 10 will be stable, and when the EGR rate (E) exceeds the set EGR rate (E), the combustion will be stable. t When the combustion of the multi-fuel engine system 10 becomes unstable, the combustion becomes unstable.

[0083] When the EGR rate (E) is determined in S15, it is at most the set EGR rate (E). t When the EGR rate (E) increases by a specific value (b%) (S16), the controller 100 can control the EGR valve 44 to relatively increase the opening of the EGR valve 44, thereby relatively increasing the EGR rate (E). As the EGR rate (E) relatively increases, the oxygen concentration in the combustion chamber 13 of the cylinder 11 relatively decreases. Therefore, due to the relatively delayed combustion center, the combustion center (COC) can be at least at the set combustion center (COC). t (See also) Figure 4 ), and can relatively reduce the maximum pressure of cylinder 11 (P m (See also) Figure 5As mentioned above, when the EGR rate (E) increases relatively, the combustion center (COC) can be relatively delayed, and the maximum pressure (P) of cylinder 11 can be relatively reduced. m ).

[0084] After the EGR rate (E) is increased by a specific value (b%) in S16, the controller 100 can re-determine whether the conditions allowing hydrogen to be mixed with gaseous fuel are met. Specifically, the controller 100 can determine whether the detected maximum pressure (Pm) of cylinder 11 is at most the design pressure (P) of cylinder 11. d And whether the detected combustion center (COC) is at least the set combustion center (COC) t (S17) to determine whether the conditions for allowing hydrogen to be mixed with gaseous fuels are met.

[0085] When the maximum pressure (P) of cylinder 11 detected in S17 is determined m At most the design pressure of cylinder 11 (P) d And the detected combustion center (COC) is at least the set combustion center (COC). t When the conditions for mixing hydrogen and gaseous fuel are met, the controller 100 can determine whether the inlet temperature (T) of the turbine 27 of the turbocharger 25 is at most the set temperature (T). a (S18). Set temperature (T) a This can be a safe temperature used to determine whether turbine 27 is damaged.

[0086] When the inlet side temperature (T) of turbine 27 is determined in S18, it is at most the set temperature (T). a When the hydrogen ratio (R) is at most a set ratio (R), the controller 100 can determine whether the hydrogen ratio (R) is at most a set ratio (R). t (S19).

[0087] When the proportion (R) of hydrogen is determined in S19, it is at most the set proportion (R). t When the hydrogen ratio (R) is increased, the control method of this disclosure can return to S13. Therefore, the controller 100 increases the hydrogen ratio (R) by a specific mixing ratio (a vol%) (S13). In other words, the hydrogen ratio (R) can be increased by a specific mixing ratio (a vol%) based on the EGR rate (E) and the inlet side temperature (T) of the turbine 27.

[0088] As described above, the EGR rate (E) is increased to maintain at most the set EGR rate (E). t After that, increase the proportion of hydrogen (R) to maintain it at most the set proportion (R). tThis improves the combustion efficiency of the multi-fuel engine system 10 and rapidly reduces greenhouse gas emissions (nitrogen oxides or methane).

[0089] When the maximum pressure (P) of cylinder 11 is determined in S14 m At most the design pressure of cylinder 11 (P) d And the detected combustion center (COC) is at least the set combustion center (COC). t When the hydrogen ratio (R) is at most a set ratio (R), the controller 100 can determine whether the hydrogen ratio (R) is at most a set ratio (R). t (S19).

[0090] When it is determined in S18 that the inlet side temperature (T) of turbine 27 exceeds the set temperature (T) a When the EGR rate (E) is reduced by a specific value (b%), the controller 100 can subtract a specific value (b%) from the EGR rate (E) (S20). The controller 100 can control the EGR valve 44 to reduce the opening of the EGR valve 44 by a specific degree, so that the EGR rate (E) can be reduced by a specific value (b%). When the EGR rate (E) is reduced by a specific value (b%), the EGR rate (E) can be reduced to the EGR rate before the increase in the EGR rate (E) in S16 (i.e., the EGR rate detected in S15).

[0091] After subtracting a specific value (b%) from the EGR rate (E), the controller 100 determines whether the multi-fuel engine system 10 is under abnormal conditions (S21).

[0092] Abnormal conditions in the multi-fuel engine system 10 can be caused by various reasons (such as gas tripping, emergency shutdown, shutdown of the multi-fuel engine system 10, or change in the mode of the multi-fuel engine system 10), leading to abnormal operation of the multi-fuel engine system 10. In the following text, gas tripping refers to the phenomenon where fuel is not completely burned and is discharged into the exhaust pipe due to abnormal combustion in the combustion chamber 13 of the cylinder 11.

[0093] When it is determined in S21 that the multi-fuel engine system 10 is under abnormal conditions, the hydrogen control valve 33b is completely closed to block hydrogen, and the on / off valve 43 of the exhaust gas recirculation system 40 is completely closed to block EGR (S22).

[0094] When it is determined in S21 that the multi-fuel engine system 10 is under normal conditions rather than abnormal conditions, the control method of this disclosure returns to S12.

[0095] When the maximum pressure (P) of the detected cylinder 11 is determined in S12 m ) Exceeds the design pressure of cylinder 11 (P) d And the detected combustion center (COC) is smaller than the set combustion center (COC) value.t When the controller 100 determines whether the multi-fuel engine system 10 is under abnormal conditions (S21), the controller 100 determines whether the multi-fuel engine system 10 is under abnormal conditions.

[0096] When it is determined in S15 that the EGR rate (E) exceeds the set EGR rate (E t When the controller 100 determines whether the multi-fuel engine system 10 is under abnormal conditions (S21), the controller 100 determines whether the multi-fuel engine system 10 is under abnormal conditions.

[0097] The above description is merely an example of the technical concept of this disclosure, and those skilled in the art can make various modifications and variations without departing from the essential features of this disclosure.

[0098] Therefore, embodiments of this disclosure are provided to illustrate the spirit and scope of this disclosure, and not to constitute a limitation thereof; thus, the spirit and scope of this disclosure are not limited by the embodiments. The scope of protection of this disclosure should be interpreted by the appended claims, and all equivalents thereof should be interpreted as being included within the scope of this disclosure.

Claims

1. A method for controlling a multi-fuel engine system configured to use a gaseous fuel and hydrogen, the method comprising: detecting a maximum pressure of a cylinder and a center of combustion during operation of the multi-fuel engine system; and determining a proportion of hydrogen to be mixed with the gaseous fuel based on the detected maximum pressure of the cylinder and the center of combustion.

2. The method of claim 1, wherein, determining whether a condition for allowing the hydrogen to be mixed with the gaseous fuel is satisfied, and wherein the proportion of hydrogen to be mixed with the gaseous fuel is determined in accordance with whether the condition for allowing the hydrogen to be mixed with the gaseous fuel is satisfied.

3. The method of claim 2, wherein, the condition for allowing the hydrogen to be mixed with the gaseous fuel is a condition that the detected maximum pressure of the cylinder is at most a design pressure of the cylinder and the detected center of combustion is at least a set center of combustion.

4. The method of claim 2, wherein, when the condition for allowing the hydrogen to be mixed with the gaseous fuel is satisfied, increasing the proportion of hydrogen to be at most a set proportion.

5. The method of claim 4, wherein, redetermining whether the condition for allowing the hydrogen to be mixed with the gaseous fuel is satisfied after the proportion of hydrogen is increased, and wherein when the condition for allowing the hydrogen to be mixed with the gaseous fuel is not satisfied, decreasing the proportion of hydrogen to the proportion of hydrogen before the proportion of hydrogen is increased.

6. The method of claim 2, wherein, detecting EGR during operation of the multi-fuel engine system, increasing an EGR rate to be at most a set EGR rate, and increasing the proportion of hydrogen based on the increased EGR rate.

7. The method of claim 6, wherein, when the condition for allowing the hydrogen to be mixed with the gaseous fuel is not satisfied, increasing the EGR rate to be at most the set EGR rate, and wherein whether the condition for allowing the hydrogen to be mixed with the gaseous fuel is satisfied is redetermined after the EGR rate is increased.

8. The method of claim 7, wherein, when the condition for allowing the hydrogen to be mixed with the gaseous fuel is satisfied after the EGR rate is increased, increasing the proportion of hydrogen based on the increased EGR rate to be at most the set proportion.

9. The method of claim 7, wherein, when the condition for allowing the hydrogen to be mixed with the gaseous fuel is not satisfied after the EGR rate is increased, decreasing the EGR rate to the EGR rate before the EGR rate is increased.

10. The method of claim 7, wherein, when the condition for allowing the hydrogen to be mixed with the gaseous fuel is satisfied after the EGR rate is increased, determining whether an inlet side temperature of a turbine of a turbocharger is at most a set temperature, wherein when the inlet side temperature of the turbine is at most the set temperature, increasing the proportion of hydrogen based on the increased EGR rate to be at most the set proportion, and wherein when the inlet side temperature of the turbine exceeds the set temperature, decreasing the EGR rate to the EGR rate before the EGR rate is decreased.

11. A multi-fuel engine system comprising: a cylinder including a combustion chamber, an intake port communicating with the combustion chamber, and an exhaust port communicating with the combustion chamber; a gas inflow valve configured to inject at least one of a gaseous fuel or a mixture of the gaseous fuel and hydrogen into the intake port; and a controller configured to determine a proportion of hydrogen to be mixed with the gaseous fuel based on a maximum pressure of the cylinder and a center of combustion of the cylinder.

12. The multi-fuel engine system according to claim 11, further comprising: a gaseous fuel supply source fluidly connected to the gas inflow valve by a gaseous fuel supply pipe; a gaseous fuel control valve provided in the gaseous fuel supply pipe; a hydrogen gas supply source fluidly connected to the gaseous inflow valve through a hydrogen gas supply pipe; and a hydrogen gas control valve provided in the hydrogen gas supply pipe, wherein the controller is configured to control the flow rate control valve in the gaseous fuel supply pipe and the flow rate control valve in the hydrogen gas supply pipe.

13. The multi-fuel engine system of claim 12, wherein, the gaseous fuel supply pipe and the hydrogen gas supply pipe are joined to each other in a main supply pipe, and wherein the main supply pipe is coupled to the gaseous inflow valve.

14. The multi-fuel engine system of claim 11, wherein, the controller is configured to: detect an EGR rate during operation of the multi-fuel engine system, increase the EGR rate to maintain at most a set EGR rate; and increase the proportion of hydrogen gas based on the increased EGR rate.

15. The multi-fuel engine system of claim 11, wherein, the controller is configured to: determine whether a condition for allowing hydrogen gas to be mixed with gaseous fuel is satisfied during operation of the multi-fuel engine system; and determine the proportion of hydrogen gas to be mixed with gaseous fuel in accordance with whether the condition for allowing hydrogen gas to be mixed with gaseous fuel is satisfied.

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