Engine device

Abstract

The invention provides an engine device which does not have an expensive sensor and can restrain the emission amount of nitrogen oxide to a target value regardless of the hydrogen mixing ratio of fuel gas. An engine device (1) that is driven by a fuel gas into which hydrogen has been mixed is provided with a control means (8) that controls the excess air ratio and / or ignition parameters of an engine (2) on the basis of the excess air ratio of a mixture of the fuel gas and air supplied to the engine (2) and the exhaust temperature of exhaust gas from the engine (2). Thus, nitrogen oxides contained in the exhaust gas are suppressed.

Description

Technical Field

[0001] This invention relates to an engine device that uses fuel gas mixed with hydrogen to drive the engine. Background Technology

[0002] Traditionally, some engine systems are driven by supplying a mixture of fuel gas and air, with the fuel gas being driven as a mixture of fuel gas and air. In such engine systems, exhaust gases containing nitrogen oxides (NOx) are emitted by burning the fuel gas. Furthermore, engine systems are required to suppress NOx emissions to meet emission regulations and maintain stable operation regardless of changes in the composition of the fuel gas supplied to the engine.

[0003] For example, Patent Document 1 discloses a control method for an engine using fuel composed of multiple different components, the concentration of which varies over time. In this control method, a first control quantity capable of adjusting the air-fuel ratio is controlled such that the air-fuel ratio exists within a band containing the stoichiometric air-fuel ratio. A second control quantity determining the air flow rate or mixture flow rate is detected, and the same air-fuel ratio control is performed to maintain the air-fuel ratio at the stoichiometric air-fuel ratio. Here, the first control quantity is the opening degree of a fuel control valve that controls the flow rate of fuel supplied to the mixer, and the second control quantity is the opening degree of the throttle valve.

[0004] Patent Document 1: Japanese Patent No. 5667413

[0005] In some engine systems, propulsion is achieved by introducing fuel gases, such as natural gas supplied from a pipeline, into the engine, whose fuel composition varies over time, and by mixing in hydrogen. However, in the prior art of air-fuel ratio control, as in Patent Document 1, deviations in fuel composition can be accommodated in engines using hydrocarbon fuel gases, but in engines using hydrogen-mixed fuel gases, in addition to reduced fuel efficiency, nitrogen oxide (NOx) emissions also increase, and therefore, deviations in the hydrogen mixing ratio cannot be accommodated.

[0006] Furthermore, in engines using fuel gas mixed with hydrogen, combustion characteristics vary significantly depending on the hydrogen mix ratio. Therefore, it is necessary to control fuel supply and engine operating conditions based on the hydrogen mix ratio. However, this requires expensive sensors such as hydrogen sensors and NOx sensors to determine the hydrogen mix ratio, raising concerns about increased costs and increased equipment complexity. Summary of the Invention

[0007] The purpose of this invention is to provide an engine device that does not require expensive sensors and can suppress nitrogen oxide emissions to a target value regardless of the hydrogen mix ratio of the fuel gas.

[0008] To solve the above-mentioned problems, the engine device of the present invention is an engine device that drives the engine by introducing fuel gas with a different fuel composition. It is characterized by having a control unit that controls the supply pressure and the ignition parameters of the engine based on the supply pressure of the fuel gas-air mixture to the engine and the exhaust temperature of the exhaust gas from the engine.

[0009] According to the present invention, an engine device can be provided that does not require expensive sensors and can operate in a manner that suppresses nitrogen oxide emissions to a target value regardless of the hydrogen mixing ratio of the fuel gas. Attached Figure Description

[0010] Figure 1 This is a schematic diagram illustrating an example of an engine device according to an embodiment of the present invention.

[0011] Figure 2 This is a schematic diagram illustrating an example of an engine device according to an embodiment of the present invention.

[0012] Figure 3 It is a graph showing the relationship between the engine's average pressure and nitrogen oxide emissions in an engine unit.

[0013] Figure 4 It is a graph showing the relationship between engine ignition timing and excess air ratio when the engine is adjusted in such a way that the nitrogen oxide emission is at a specified target value.

[0014] Figure 5 It is a graph showing the relationship between engine ignition timing and exhaust temperature when the engine is adjusted in such a way that the nitrogen oxide emission is a specified target value.

[0015] Figure 6 This is a graph showing the relationship between excess air ratio and exhaust temperature in the engine device according to the embodiments of the present invention, when the nitrogen oxide emission is adjusted to a predetermined target value.

[0016] Figure 7 This is a flowchart illustrating an example of combustion control operations performed by a control unit in an engine device according to an embodiment of the present invention.

[0017] Explanation of reference numerals in the attached figures

[0018] 1… Engine unit; 2… Engine; 3… Intake passage; 4… Exhaust passage; 5… Fuel supply device; 5a… Fuel flow regulating valve; 5b… Venturi mixer; 5c… Intake valve; 6… Excess air adjustment device; 6a… Throttle valve; 7… Ignition device; 8… Control unit; 9… Fuel supply unit; 11… Cylinder block; 12… Cylinder; 12a… Combustion chamber; 13… Cylinder; 14… Piston; 15… Cylinder head; 18… Connecting rod; 19… Crankshaft; 20… Speed ​​sensor; 21… Torque sensor; 22… Intake port; 23… Exhaust port; 24… Intake valve; 25… Exhaust valve; 27… Exhaust temperature sensor; 28… Oxygen concentration sensor. Detailed Implementation

[0019] The engine device 1, which is an embodiment of the present invention, will be described with reference to the accompanying drawings. Figure 1 and Figure 2 As shown, the engine unit 1 includes an engine 2, an intake passage 3, an exhaust passage 4, a fuel supply device 5, an excess air rate adjustment device 6, an ignition device 7, and a control unit 8.

[0020] In this embodiment, in particular, the engine unit 1 is a gas turbine engine that is driven by introducing a fuel gas, such as natural gas supplied from a pipeline, mixed with hydrogen, into the combustion chamber 12a of the engine 2. This fuel gas has a composition that varies over time. For example, the engine unit 1 supplies the engine 2 with fuel gas primarily composed of hydrocarbon fuels such as light oil, kerosene, or heavy oil, and / or non-hydrocarbon fuels such as ammonia, further mixed with hydrogen, via a fuel supply device 5. The fuel gas is supplied to the combustion chamber 12a as a mixture with air.

[0021] Engine 2 is, for example, a four-stroke engine, configured to have multiple cylinders 12 in the cylinder block 11, but... Figure 1 and Figure 2 Only one cylinder, 12, is shown in the diagram. (For example...) Figure 1 and Figure 2 As shown, each cylinder 12 consists of a cylinder 13, a piston 14, and a cylinder head 15, and an ignition device 7 is provided for each cylinder 12.

[0022] Cylinder 13 is formed in a cylindrical shape within cylinder block 11, for example, and piston 14 is slidably housed within cylinder 13. Cylinder head 15 is mounted on the upper side of cylinder 13, and combustion chamber 12a is formed on the inner side through cylinder 13 and cylinder head 15.

[0023] Below cylinder 13, crankshaft 19 is connected to piston 14 via connecting rod 18. The reciprocating motion of piston 14 is converted into rotational motion of crankshaft 19 via connecting rod 18.

[0024] A speed sensor 20, such as an encoder, is installed in cylinder 13 to detect the rotational speed of crankshaft 19, i.e., the rotational speed of engine 2. The speed sensor 20 sends the detection result to control unit 8. A torque sensor 21 is installed in cylinder 13 near crankshaft 19 to detect the engine load (engine torque) of engine 2. The torque sensor 21 sends the detection result to control unit 8.

[0025] In addition, the cylinder head 15 has an intake port 22 and an exhaust port 23 that communicate with the combustion chamber 12a of the cylinder 13, and has an intake valve 24 and an exhaust valve 25 that open and close the intake port 22 and the exhaust port 23 relative to the combustion chamber 12a, respectively.

[0026] The intake port 22 is connected to the intake passage 3, introducing the air-fuel mixture supplied from the intake passage 3 into the combustion chamber 12a. The exhaust port 23 is connected to the exhaust passage 4, discharging the exhaust gas generated in the combustion chamber 12a into the exhaust passage 4. By opening the intake valve 24, the air-fuel mixture can be drawn into the combustion chamber 12a through the intake port 22. On the other hand, by opening the exhaust valve 25, the exhaust gas generated in the combustion chamber 12a can be discharged through the exhaust port 23.

[0027] In other words, the intake passage 3 is connected to the intake port 22 of each cylinder 12 of the engine 2, and supplies compressed and cooled air to each cylinder 12 through the intake port 22. The exhaust passage 4 is connected to the exhaust port 23 of each cylinder 12 of the engine 2, and discharges the exhaust gas generated in each cylinder 12 through the exhaust port 23.

[0028] In addition, Figure 1 and Figure 2 The diagram illustrates an example where the intake passage 3 is directly connected to the intake port 22. However, to connect the intake passage 3 to each intake port 22 of the multiple cylinders 12, an intake manifold with branch flow paths branching from the intake passage 3 to the multiple cylinders 12 can also be provided between the intake passage 3 and the engine 2. Additionally, in Figure 1 and Figure 2 The diagram illustrates an example where the exhaust passage 4 is directly connected to the exhaust port 23. However, when the exhaust passage 4 is connected to the exhaust ports 23 of the multiple cylinders 12, an exhaust manifold with branch flow paths branching from the exhaust passage 4 to the multiple cylinders 12 can also be provided between the exhaust passage 4 and the engine 2.

[0029] In the intake passage 3, an air filter (not shown) can be installed to purify fresh air and introduce it into the intake passage 3, and an intercooler (not shown) can be installed to cool the air flowing in the intake passage 3.

[0030] In the intake passage 3, a throttle valve 6a is provided as an excess air rate adjustment device 6 for regulating the amount of air or air-fuel mixture supplied to the intake port 22. The throttle valve 6a is controlled and its opening is adjusted by the control unit 8, and the amount of air or air-fuel mixture supplied to the intake port 22 is adjusted according to the opening of the throttle valve 6a. Thus, the throttle valve 6a functions as an excess air rate adjustment device 6 for adjusting the amount of air supplied from the intake passage 3 to the engine 2 and adjusting the excess air rate of the air-fuel mixture supplied to the engine 2.

[0031] An exhaust temperature sensor 27 is installed in the exhaust passage 4 to detect the exhaust temperature of the exhaust gas discharged from the engine 2 into the exhaust passage 4. The exhaust temperature sensor 27 sends the detection result to the control unit 8. In addition, an oxygen concentration sensor 28 is installed in the exhaust passage 4 to detect the oxygen concentration of the exhaust gas discharged from the engine 2 into the exhaust passage 4. The oxygen concentration sensor 28 sends the detection result to the control unit 8.

[0032] The fuel supply device 5 is installed in the intake passage 3 and is controlled by the control unit 8. It supplies fuel gas from the fuel supply section 9, such as pipelines, into the intake passage 3. A mixture of air supplied from the upstream side of the intake passage 3 and fuel gas supplied from the fuel supply section 9 is supplied to the combustion chamber 12a from the intake port 22. The fuel supply device 5 is controlled by the control unit 8 to regulate the amount and timing of fuel gas supply.

[0033] like Figure 1 As shown, the fuel supply device 5 is configured as a mixer, including a fuel flow regulating valve 5a for adjusting the flow rate of fuel gas, a fuel control valve for controlling the amount of fuel gas supplied to the intake passage 3, and a Venturi mixer 5b for mixing the fuel gas with the air flowing in the intake passage 3. Alternatively, as... Figure 2 As shown, the fuel supply device 5 is configured in an injection manner. As a fuel control valve, it may be equipped with an intake valve 5c that injects fuel gas into the intake passage 3, or it may be equipped with an injector or the like instead of an intake valve 5c.

[0034] Fuel control valves such as fuel flow regulating valve 5a or intake valve 5c function as an air excess rate regulating device 6, which adjusts the amount of fuel gas supplied to the intake passage 3 to regulate the air excess rate of the mixture supplied to the engine 2.

[0035] Ignition device 7 is installed in cylinder head 15 of each cylinder 12. Ignition device 7 is, for example, a device using spark plugs for spark ignition. The spark ignition device 7 is controlled by control unit 8 to control the timing and duration of energizing the spark plug, and to control ignition parameters such as ignition timing corresponding to the energizing timing and ignition energy corresponding to the energizing duration.

[0036] Alternatively, the ignition device 7 can be a micro-pilot type device that injects a small amount of liquid fuel, consisting of an injector that injects liquid fuel supplied from a liquid fuel tank (not shown) into the combustion chamber 12a (sub-chamber) below the cylinder head 15. In the micro-pilot type ignition device 7, the control unit 8 controls the timing and duration of energizing the injector, and controls ignition parameters such as the injection timing (ignition timing) corresponding to the energizing timing and the fuel injection quantity corresponding to the energizing duration, i.e., ignition energy.

[0037] The control unit 8 is a computer such as the ECU (Engine Control Unit) that controls the operation of the engine 2. It has a CPU, ROM, RAM, etc., and constitutes the various parts that control the engine 2. The control unit 8 can also store various programs for controlling the engine 2, and control the engine 2 by reading out the programs and executing them.

[0038] In this embodiment, the control unit 8 controls the opening of fuel control valves such as fuel flow adjustment valve 5a or intake valve 5c, or throttle valve 6a, so as to achieve a mixture flow rate determined by engine load and engine speed, as a basic control.

[0039] When the engine speed, load, or excess air ratio changes due to changes in fuel gas composition, the opening of fuel control valves such as fuel flow regulating valve 5a or intake valve 5c or throttle valve 6a is adjusted based on the detection results from speed sensor 20, torque sensor 21 and oxygen concentration sensor 28 installed in exhaust passage 4, so as to achieve the target speed, load and excess air ratio.

[0040] In addition, the control unit 8 controls the combustion of the engine 2 by suppressing the amount or proportion of nitrogen oxides contained in the exhaust gas based on the excess air ratio of the mixture supplied from the intake passage 3 to the engine 2 and the exhaust temperature of the exhaust gas discharged from the engine 2.

[0041] First, the combustion control of engine 2 will be explained. In engine device 1, which utilizes fuel gas mixed with hydrogen as described in this invention, the hydrogen mixing ratio of the supplied fuel gas varies. The nitrogen oxides contained in the exhaust gas of engine device 1 vary depending on the hydrogen mixing ratio of the fuel gas supplied to engine 2, the engine speed, load, excess air ratio, and ignition timing.

[0042] exist Figure 3The diagram illustrates the relationship between the average pressure of the combustion gases in combustion chamber 12a and the amount of nitrogen oxides emitted, under the same operating conditions, for each hydrogen mix ratio of the combustion gases. According to this relationship, a higher hydrogen mix ratio in combustion chamber 12a results in a greater amount of nitrogen oxides emitted. However, even with the same hydrogen mix ratio, the amount (or proportion) of nitrogen oxides emitted can be reduced by delaying ignition timing or by leaning the fuel gas mixture, i.e., increasing the excess air ratio.

[0043] In addition, Figure 4 The diagram illustrates the relationship between the ignition timing of engine 2 and the excess air ratio of the air-fuel mixture supplied to engine 2 when engine 1 is operated with engine 1 running at a predetermined target value for each hydrogen mixing ratio in the combustion gases. Figure 4 The correlation shown indicates that, given the target value for nitrogen oxide emissions, the excess air ratio relative to ignition timing (ignition timing relative to excess air ratio) varies depending on the hydrogen mix ratio. However, regardless of the hydrogen mix ratio, the trend of lower excess air ratio with more delayed ignition timing is characterized by the same linear correlation.

[0044] exist Figure 5 The diagram illustrates the relationship between the ignition timing of engine 2 and the exhaust temperature of the exhaust gas from engine 2 when engine 1 is operated with engine 1 running at a predetermined target value for each hydrogen mixing ratio in the combustion gases. Figure 5 The correlation shown indicates that, given a specified target value for nitrogen oxide emissions, the exhaust temperature relative to ignition timing (ignition timing relative to exhaust temperature) varies depending on the hydrogen mix ratio. However, regardless of the hydrogen mix ratio, the trend of higher exhaust temperature with more delayed ignition timing is characterized by the same linear correlation.

[0045] In addition, based on Figure 4 Correlation and Figure 5 The relevant relationship, in Figure 6 The diagram shows the relationship between the excess air ratio of the mixture supplied to engine 2 and the exhaust temperature of the exhaust gas from engine 2, under the condition that combustion occurs at each ignition timing, when engine 1 is operated with a predetermined target value for nitrogen oxide emissions, for each hydrogen mixing ratio of the combustion gases. Figure 6 When the nitrogen oxide emissions reach a specified target value, the correlation between excess air ratio and exhaust temperature exhibits a trend where the higher the excess air ratio, the lower the exhaust temperature. This linear correlation remains largely unchanged regardless of the hydrogen mixing ratio. In other words, for engine unit 1, if the excess air ratio and exhaust temperature are... Figure 6 The linear correlation shown indicates that the emission amount of nitrogen oxides becomes the specified target value.

[0046] Therefore, in engine unit 1, based on... Figure 6 The linear correlation between the excess air ratio and exhaust temperature for each hydrogen mixing ratio is shown. A target line L is set for the engine unit 1 during operation, and for each target value of nitrogen oxide emissions, it is stored as a mapping. Furthermore, the correlation between the excess air ratio and exhaust temperature can be a linear correlation with a certain width, allowing a certain range (width) of exhaust temperature (or a certain excess air ratio) relative to a specified excess air ratio (or specified exhaust temperature). That is, the target line L for engine unit 1 during operation can also have a certain width.

[0047] In addition, in engine unit 1, since the relationship between excess air rate and exhaust temperature varies depending on the operating conditions of engine 2 such as engine speed and engine load, the target line L for engine unit 1 during operation is pre-stored as a mapping for each operating condition of engine unit 1.

[0048] If the excess air ratio and exhaust temperature detected during engine unit 1 deviate from the aforementioned correlation between excess air ratio and exhaust temperature, then the nitrogen oxides in the exhaust gas of engine unit 1 do not meet the specified target value.

[0049] Therefore, in the engine device 1 of this embodiment, as the combustion control of the engine 2, the control unit 8 controls each part based on the excess air ratio of the fuel gas and the exhaust temperature of the exhaust gas during operation, and the engine speed and engine load of the engine 2, so as to maintain a certain correlation between the excess air ratio and the exhaust temperature.

[0050] Specifically, the control unit 8 controls the excess air ratio of engine 2 and the ignition parameters (ignition timing, ignition energy, etc.) when igniting engine 2, thereby suppressing nitrogen oxides in the exhaust gas to meet emission control limits regardless of the hydrogen mix ratio, or improving the fuel efficiency of the fuel gas supplied to engine 2. At this time, the control unit 8 performs feedback control on the excess air ratio and ignition parameters of engine 2 to ensure that the excess air ratio and exhaust temperature detected during operation meet the aforementioned correlation between excess air ratio and exhaust temperature.

[0051] Regardless of the hydrogen mix ratio, engine unit 1 can improve fuel efficiency by advancing the ignition timing and / or enriching the fuel gas (reducing the excess air ratio). In addition, regardless of the hydrogen mix ratio, engine unit 1 can reduce nitrogen oxide emissions by delaying the ignition timing and / or leaning the fuel gas (increasing the excess air ratio).

[0052] In the engine unit 1 of this embodiment, relational information such as formulas and mappings representing the relationship between excess air rate and exhaust temperature are stored in advance in the control unit 8. For example, the relationship between excess air rate and exhaust temperature can be obtained from data detected during experimental operation of the engine unit 1 and the relational information can be constructed in advance. Alternatively, the relational information can be obtained from data detected during actual operation of the engine unit 1 and constructed in real time. In addition, in the engine unit 1, relational information representing the relationship between excess air rate and exhaust temperature for each operating condition of the engine 2, such as engine speed and engine load (e.g., for each combination of engine speed and engine load), is stored in the control unit 8.

[0053] In addition, in engine unit 1, the hydrogen mixing ratio is inferred based on the correlation between ignition timing and excess air ratio, and the ignition timing and excess air ratio during operation. The correction amount of ignition timing and excess air ratio is calculated based on the inferred hydrogen mixing ratio, and the ignition timing and excess air ratio are corrected based on the correction amount.

[0054] Next, refer to Figure 7 The flowchart illustrates a specific example of combustion control of engine 2 performed by control unit 8.

[0055] First, the control unit 8 assumes that the hydrogen mixing ratio of the combustion gas supplied to the engine 2 is 0 (step S1).

[0056] During the operation of engine unit 1, control unit 8 detects the engine speed of engine 2 via speed sensor 20 and the engine load of engine 2 via torque sensor 21. Then, control unit 8 reads the correlation information between excess air ratio and exhaust temperature corresponding to the detected engine speed and engine load of engine 2 from the stored correlation information between excess air ratio and exhaust temperature.

[0057] During operation of the engine unit 1, the control unit 8 detects the oxygen concentration of the exhaust gas discharged from the engine 2 to the exhaust passage 4 via the oxygen concentration sensor 28, and calculates the excess air ratio of the fuel gas supplied from the intake passage 3 to the engine 2 based on the oxygen concentration. Additionally, during operation of the engine unit 1, the control unit 8 detects the exhaust temperature of the exhaust gas discharged from the engine 2 to the exhaust passage 4 via the exhaust temperature sensor 27 (step S2).

[0058] Then, the control unit 8 compares the excess air rate and exhaust temperature (current excess air rate and current exhaust temperature) with the read correlation information of excess air rate and exhaust temperature, and determines whether the current excess air rate and current exhaust temperature are consistent with the correlation information (step S3). For example, the control unit 8 determines whether the current excess air rate and current exhaust temperature are within the range of... Figure 5 The relevant information shown is the target line L for excess air ratio and exhaust temperature.

[0059] If the current excess air ratio and current exhaust temperature are on the target line L (step S3: "Yes"), the control unit 8 does not correct the excess air ratio and ignition parameters, and ends the process.

[0060] On the other hand, if the current excess air ratio and the current exhaust temperature are not on the target line L (step S3: "No"), the control unit 8 corrects the excess air ratio and ignition parameters, such as advancing or delaying the ignition timing, so that the excess air ratio and exhaust temperature are on the target line L (step S4).

[0061] Additionally, the control unit 8 infers the hydrogen mixing ratio based on the relationship between ignition timing and excess air ratio (step S5). For example, the control unit 8 based on... Figure 4 The relationship between ignition timing and excess air ratio for each hydrogen mixing ratio shown can be used to deduce and correct the hydrogen mixing ratio corresponding to the current excess air ratio and the corrected ignition timing. At this time, the control unit 8 can... Figure 4 The hydrogen blending ratio is inferred from the curves of each hydrogen blending ratio that are closest to the corrected ignition timing and the current excess air ratio.

[0062] Then, based on the inferred hydrogen mixing ratio, the control unit 8 adjusts it to the optimal excess air ratio (step S6). For example, the control unit 8 adjusts the inferred hydrogen mixing ratio to the optimal excess air ratio. Figure 4 In the chart, the excess air ratio is corrected to the corrected ignition timing.

[0063] Then, the control unit 8 returns to step S2 and keeps the engine 2 running according to the corrected ignition timing and excess air ratio.

[0064] As described above, according to this embodiment, the engine unit 1 is an engine unit driven by fuel gas mixed with hydrogen, and includes a control unit 8. This control unit 8 controls the excess air ratio and / or the ignition parameters of the engine 2 based on the excess air ratio of the fuel gas-air mixture supplied to the engine 2 and the exhaust temperature of the exhaust gas from the engine 2, in order to suppress nitrogen oxides contained in the exhaust gas. For example, the control unit 8 controls the amount or proportion of nitrogen oxides contained in the exhaust gas.

[0065] In the hydrogen-fueled engine unit 1, to suppress nitrogen oxide emissions, adjustments are needed to lean the fuel gas (increase the excess air ratio) and retard the ignition timing (ignition lag) compared to conventional gas engines. In this case, the adjustments to the excess air ratio and ignition timing vary depending on the hydrogen-fuel mixture ratio, but this ratio is uncertain and fluctuates, requiring expensive sensors to determine it. In contrast, engine unit 1 does not have expensive sensors. Regardless of the hydrogen-fuel mixture ratio, by adjusting the excess air ratio and ignition timing to maintain the correlation between the excess air ratio and exhaust temperature, nitrogen oxide emissions can be suppressed to a predetermined target value.

[0066] In addition, according to this embodiment, the control unit 8 controls the excess air rate and / or ignition parameters based on the excess air rate and exhaust temperature, ignition parameters, engine speed and / or engine load, so as to suppress nitrogen oxides contained in the exhaust gas.

[0067] Therefore, even when the relationship between excess air rate and exhaust temperature for suppressing nitrogen oxide emissions differs for each operating condition, such as engine speed and engine load, engine unit 1 can utilize the relationship between excess air rate and exhaust temperature corresponding to various operating conditions.

[0068] Furthermore, according to this embodiment, the control unit 8 stores in advance information about the relationship between nitrogen oxides becoming a certain excess air rate and exhaust temperature based on operating conditions corresponding to engine speed and / or engine load, and controls the excess air rate and / or the aforementioned ignition parameters based on the relevant relationship information.

[0069] Therefore, the engine unit 1 has information on the relationship between excess air rate and exhaust temperature in the mapping and other systems for each operating condition. Based on the information on the relationship between excess air rate and exhaust temperature corresponding to the operating conditions, the excess air rate and ignition parameters are controlled to correct the deviation of the measured values ​​of excess air rate and exhaust temperature, thereby suppressing the emission of nitrogen oxides to the specified target value.

[0070] Furthermore, according to this embodiment, the control unit 8 estimates the hydrogen mixing ratio in the fuel gas based on operating conditions, excess air ratio, and / or corrections to ignition parameters.

[0071] Therefore, the engine unit 1 can determine the hydrogen mixing ratio without having expensive sensors for measuring the hydrogen mixing ratio of fuel gas, and further, can perform combustion control based on the estimated hydrogen mixing ratio.

[0072] Furthermore, according to this embodiment, in the engine unit 1, the engine 2 is a four-stroke engine and includes: an ignition device 7 that ignites the engine 2 by spark ignition or micro-pilot ignition; a fuel supply device 5 that supplies fuel gas to the intake side of the engine 2 by injection or mixing; and an excess air rate adjustment device 6 that adjusts the excess air rate based on the oxygen concentration in the exhaust gas by at least one of a fuel flow adjustment valve 5a and a throttle valve 6a.

[0073] Moreover, in such an engine device 1, the control unit 8 adjusts the excess air rate by controlling at least one of the opening of the fuel flow adjustment valve 5a and the opening of the throttle valve 6a.

[0074] Therefore, engine unit 1 can more accurately control the excess air ratio to satisfy the relationship between excess air ratio and exhaust temperature.

[0075] Furthermore, in such an engine device 1, the control unit 8 controls the ignition parameters by controlling the timing of the energization of the spark plug in the spark ignition method.

[0076] As a result, engine unit 1 can more accurately control the ignition parameters that satisfy the relationship between excess air rate and exhaust temperature.

[0077] According to this embodiment, the engine unit 1 feeds fuel containing hydrocarbons as the main component into the engine 2 as fuel gas.

[0078] Therefore, engine unit 1 can operate in accordance with fuel gas in which hydrogen is mixed into fuel that is mainly composed of hydrocarbons, so that the emission of nitrogen oxides meets the limit value.

[0079] Furthermore, in the above embodiments, an example was described in which the hydrogen mixing ratio was inferred based on the correlation between ignition timing and excess air ratio and the ignition timing and excess air ratio during operation in engine device 1, and the correction amount of ignition timing and excess air ratio was calculated using the inferred value of hydrogen mixing ratio, but the present invention is not limited to this example.

[0080] In other embodiments, in engine unit 1, control unit 8 determines whether the hydrogen mixing ratio of the fuel gas is trending upwards or downwards based on the correlation information between excess air ratio and exhaust temperature. Then, according to the determination result, control unit 8 adjusts excess air ratio and / or ignition timing by a predetermined amount, and performs feedback control on excess air ratio and ignition timing.

[0081] For example, control unit 8 detects the current excess air ratio and the current exhaust temperature. Based on the correlation information between the excess air ratio and the exhaust temperature, and considering the current excess air ratio and / or the current exhaust temperature, if the exhaust temperature is lower than the target exhaust temperature, control unit 8 determines that the hydrogen mixing ratio is increasing. Conversely, if the exhaust temperature is higher than the target exhaust temperature, control unit 8 determines that the hydrogen mixing ratio is decreasing.

[0082] If the control unit 8 determines that the hydrogen mixing ratio is trending upward, it performs at least one of increasing the prescribed amount of excess air and delaying the prescribed amount of ignition timing. Conversely, if the control unit 8 determines that the hydrogen mixing ratio is trending downward, it performs at least one of decreasing the prescribed amount of excess air and advancing the prescribed amount of ignition timing.

[0083] Then, the control unit 8 detects the current excess air ratio and the current exhaust temperature again. Based on the correlation information between the excess air ratio and the exhaust temperature, it determines whether the hydrogen mixing ratio is trending upwards or downwards. If the hydrogen mixing ratio is neither increasing nor decreasing, the control unit 8 terminates the feedback control of the excess air ratio and ignition timing. Otherwise, if the hydrogen mixing ratio is either increasing or decreasing, the feedback control of the excess air ratio and ignition timing at the specified amounts is repeated.

[0084] As described above, in the engine device 1 according to other embodiments, the control unit 8, based on the correlation information between excess air ratio and exhaust temperature, performs at least one of increasing excess air ratio and delaying ignition timing as an ignition parameter when the hydrogen mixing ratio of fuel gas is increasing.

[0085] In engine unit 1, if the proportion of hydrogen mixed in increases, the emission of nitrogen oxides increases. In contrast, in other embodiments, by leasing the fuel gas (increasing the excess air ratio) and delaying the ignition timing, the relationship between the excess air ratio and the exhaust temperature is maintained, thereby enabling the emission of nitrogen oxides to be suppressed to a target value while aiming to improve fuel efficiency.

[0086] In addition, according to the engine device 1 of other embodiments, the control unit 8, based on the correlation information between excess air rate and exhaust temperature, performs at least one of reducing excess air rate and advancing ignition timing as an ignition parameter when the hydrogen mixing ratio of fuel gas is decreasing.

[0087] In engine unit 1, if the hydrogen mixing ratio is reduced, the amount of nitrogen oxide emissions decreases, but fuel efficiency deteriorates. In contrast, in other embodiments, by enriching the fuel gas (reducing the excess air ratio) and advancing the ignition timing to maintain the relationship between the excess air ratio and exhaust temperature, it is possible to prevent fuel efficiency from deteriorating too much and suppress the amount of nitrogen oxide emissions to a target value.

[0088] Alternatively, engine unit 1 can be a gas engine that can be driven by injecting fuel gas mixed with hydrogen into engine 2, or it can be a dual-fuel engine that can be driven by injecting fuel gas mixed with hydrogen into engine 2, as well as at least one of liquid fuels such as light oil or heavy oil.

[0089] Furthermore, the present invention can be appropriately modified without departing from the spirit or idea of ​​the invention as can be read from the claims and description as a whole, and the engine device with such modifications is also included in the technical concept of the present invention.

[0090] [Notes on the Invention]

[0091] Hereinafter, a summary of the invention extracted from the above embodiments will be noted. Furthermore, the structures and processing functions described in the following notes can be selected and combined arbitrarily.

[0092] <Postscript 1>

[0093] An engine device that utilizes fuel gas mixed with hydrogen for propulsion, characterized in that...

[0094] The system includes a control unit that controls the excess air ratio and / or the ignition parameters of the engine based on the excess air ratio of the fuel-air mixture supplied to the engine and the exhaust temperature of the exhaust gas from the engine.

[0095] <Appendix 2>

[0096] According to the engine device described in Appendix 1, its characteristic is that,

[0097] The aforementioned control unit controls the amount or proportion of nitrogen oxides contained in the aforementioned exhaust gas.

[0098] <Appendix 3>

[0099] According to the engine device described in Appendix 1, its characteristic is that,

[0100] The aforementioned control unit controls the aforementioned excess air ratio and / or the aforementioned ignition parameters based on the aforementioned excess air ratio, the aforementioned exhaust temperature, the aforementioned ignition parameters, the aforementioned engine speed, and / or engine load.

[0101] <Appendix 4>

[0102] According to the engine device described in Appendix 3, its characteristic is that,

[0103] The control unit stores in advance information about the relationship between the nitrogen oxides and the excess air rate and the exhaust temperature, based on the operating conditions corresponding to the engine speed and / or the engine load, and controls the excess air rate and / or the ignition parameters based on the information about the relationship.

[0104] <Appendix 5>

[0105] According to the engine device described in Appendix 4, its characteristic is that,

[0106] Based on the aforementioned operating conditions, the aforementioned excess air ratio, and / or the aforementioned correction amount for the ignition parameters, the aforementioned control unit estimates the hydrogen mixing ratio in the aforementioned fuel gas.

[0107] <Appendix 6>

[0108] The engine device described in any one of Appendices 1 to 5 is characterized in that,

[0109] The aforementioned engine is a four-stroke engine and possesses the following characteristics:

[0110] The ignition device ignites the engine using spark ignition or micro-pilot ignition.

[0111] A fuel supply device supplies the fuel gas to the intake side of the engine via injection or mixing; and

[0112] An excess air rate adjustment device adjusts the excess air rate based on the oxygen concentration in the exhaust gas by means of at least one of a fuel flow adjustment valve and a throttle valve.

[0113] <Appendix 7>

[0114] According to the engine device described in Appendix 6, its characteristic is that,

[0115] The aforementioned control unit adjusts the excess air ratio by controlling at least one of the opening degree of the aforementioned fuel flow adjustment valve and the opening degree of the aforementioned throttle valve.

[0116] <Postscript 8>

[0117] According to the engine assembly described in Appendix 6 or 7, its characteristic is that,

[0118] The aforementioned control unit controls the ignition parameters by controlling the timing of energizing the spark plug in the aforementioned spark ignition method.

[0119] <Postscript 9>

[0120] The engine device described in any one of Appendices 1 to 8 is characterized in that,

[0121] The fuel, which contains hydrocarbons as its main component, is fed into the engine as the aforementioned fuel gas.

[0122] <Postscript 10>

[0123] The engine device described in any one of Appendices 1 to 9 is characterized in that,

[0124] Based on the correlation information between the excess air ratio and the exhaust temperature, the control unit performs at least one of increasing the excess air ratio and delaying the ignition timing, which is an ignition parameter, when the hydrogen mixing ratio of the fuel gas is increasing.

[0125] <Postscript 11>

[0126] The engine device described in any one of Appendices 1 to 10 is characterized in that,

[0127] Based on the relationship information between the excess air ratio and the exhaust temperature, the control unit performs at least one of reducing the excess air ratio and advancing the ignition timing, which is an ignition parameter, when the hydrogen mixing ratio of the fuel gas is decreasing.

Claims

1. An engine device that utilizes fuel gas mixed with hydrogen for propulsion, characterized in that, The system includes a control unit that controls the excess air ratio and / or the engine's ignition parameters based on the excess air ratio of the fuel-air mixture supplied to the engine and the exhaust temperature of the exhaust gas from the engine.

2. The engine device according to claim 1, characterized in that, The control unit controls the amount or proportion of nitrogen oxides contained in the exhaust gas.

3. The engine device according to claim 1, characterized in that, The control unit controls the excess air ratio and / or the ignition parameters based on the excess air ratio, the exhaust temperature, the ignition parameters, the engine speed, and / or the engine load.

4. The engine device according to claim 3, characterized in that, The control unit, based on the operating conditions corresponding to the engine speed and / or the engine load, pre-stores information relating the excess air rate and the exhaust temperature to the nitrogen oxides, and controls the excess air rate and / or the ignition parameters based on the information relating to the excess air rate and / or the exhaust temperature.

5. The engine device according to claim 4, characterized in that, The control unit estimates the hydrogen mixing ratio in the fuel gas based on the operating conditions, the excess air ratio, and / or the correction amount of the ignition parameters.

6. The engine device according to claim 1, characterized in that, The engine is a four-stroke engine and has the following features: An ignition device that ignites the engine using spark ignition or micro-pilot ignition; A fuel supply device supplies fuel gas to the intake side of the engine via injection or mixing. as well as An excess air rate adjustment device adjusts the excess air rate based on the oxygen concentration in the exhaust gas by means of at least one of a fuel flow adjustment valve and a throttle valve.

7. The engine device according to claim 6, characterized in that, The control unit adjusts the excess air ratio by controlling at least one of the opening degree of the fuel flow adjustment valve and the opening degree of the throttle valve.

8. The engine device according to claim 6, characterized in that, The control unit controls the ignition parameters by controlling the timing of energizing the spark plug in the spark ignition method.

9. The engine device according to claim 1, characterized in that, The fuel gas, which contains hydrocarbons as its main component, is introduced into the engine.

10. The engine device according to claim 1, characterized in that, Based on the correlation information between the excess air ratio and the exhaust temperature, when the hydrogen mixing ratio of the fuel gas is on an increasing trend, the control unit performs at least one of increasing the excess air ratio and delaying the ignition timing, which is the ignition parameter.

11. The engine device according to claim 1, characterized in that, Based on the correlation information between the excess air ratio and the exhaust temperature, when the hydrogen mixing ratio of the fuel gas is decreasing, the control unit performs at least one of reducing the excess air ratio and advancing the ignition timing, which is the ignition parameter.

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