Engine control device, engine control method and procedure

Abstract

An engine control device, when controlling the valve opening for adjusting the flow rate of the air-fuel mixture in an engine, corrects the valve opening based on the deviation between a reference value and a current value of the exhaust temperature, i.e., exhaust temperature deviation.

Description

Technical Field

[0001] This disclosure relates to engine control devices, engine control methods, and procedures. This application claims priority based on Japanese Patent Application No. 2021-020659 filed on February 12, 2021, the contents of which are incorporated herein by reference. Background Technology

[0002] Four-stroke engines, including four-stroke gas turbine engines and four-stroke gasoline engines, experience a decline in volumetric efficiency over the years. Volumetric efficiency is a value that evaluates the intake performance of a four-stroke engine. If volumetric efficiency decreases, the amount of air that can be supplied to the cylinder decreases, resulting in a richer air-fuel ratio. This leads to increased exhaust temperature and increased NOx (nitrogen oxides) emissions. National or local government limits NOx emissions, requiring operation within these limits.

[0003] Patent Document 1 describes a gas engine control device that, in response to the decrease in intake air volume due to years of deterioration, uses a predetermined opening correction value to correct the opening of the fuel gas supply regulating valve. This gas engine control device includes an opening adjustment unit that adjusts the fuel gas supply regulating unit so that the combustion variation value, based on the difference between the instantaneous engine speed during the combustion stroke of each cylinder in the combustion cycle and the average engine speed of one combustion cycle, converges to a target combustion variation value based on the engine load. Furthermore, within a predetermined period, the opening of the fuel gas supply regulating valve, calculated based on the target combustion variation value, is forcibly increased or decreased by a predetermined amount. The opening correction value is calculated based on the maximum and minimum values ​​of the opening during the convergence process towards the target combustion variation value.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent No. 5033029 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] As mentioned above, in the gas engine control device described in Patent Document 1, when calculating the opening correction value, the opening of the fuel gas supply adjustment valve, calculated based on the target combustion variation value, must be forcibly increased or decreased by a predetermined amount. Therefore, there is a problem that the above-mentioned gas engine control device is sometimes difficult to use in environments where it is difficult to operate by forcibly increasing or decreasing the opening of the fuel gas supply adjustment valve by a predetermined amount.

[0009] This disclosure was created to solve the above-mentioned problems, and its purpose is to provide an engine control device, engine control method and program that can easily calculate correction values ​​in engine control.

[0010] Technical solutions for solving the problem

[0011] To address the aforementioned problems, this disclosure provides an engine control device in which, when controlling the opening of a valve that adjusts the flow rate of the air-fuel mixture in the engine, the opening is corrected based on the deviation between a reference value and a current value of the exhaust temperature, i.e., the exhaust temperature deviation.

[0012] This disclosure provides an engine control method, which includes the following steps: when controlling the opening of a valve that adjusts the flow rate of the air-fuel mixture in the engine, the opening is corrected based on the deviation between a reference value and a current value of the exhaust temperature, i.e., the exhaust temperature deviation.

[0013] This disclosure provides a program that causes a computer to perform the following steps: when controlling the opening of a valve that adjusts the flow rate of an engine mixture, correcting the opening based on the deviation between a reference value and a current value of the exhaust temperature, i.e., exhaust temperature deviation.

[0014] Invention Effects

[0015] Based on the engine control device, engine control method and procedure disclosed herein, correction values ​​in engine control can be easily calculated. Attached Figure Description

[0016] Figure 1 This is a schematic structural diagram of the engine according to an embodiment of the present disclosure.

[0017] Figure 2 This is a block diagram illustrating a structural example of a gas engine control device according to the first embodiment of this disclosure.

[0018] Figure 3 This is a flowchart illustrating an example of the operation of the gas engine control device according to the first embodiment of this disclosure.

[0019] Figure 4 This is a characteristic diagram showing the simulation results of an example of the operation of the gas engine control device according to the first embodiment of this disclosure.

[0020] Figure 5 This is a block diagram illustrating a structural example of a gas engine control device according to the second embodiment of this disclosure.

[0021] Figure 6 This is a flowchart illustrating an example of the operation of the gas engine control device according to the second embodiment of this disclosure.

[0022] Figure 7This is a characteristic diagram showing the simulation results of an example of the operation of the gas engine control device according to the second embodiment of this disclosure.

[0023] Figure 8 This is a block diagram illustrating a structural example of a gas engine control device according to the third embodiment of this disclosure.

[0024] Figure 9 This is a flowchart illustrating an example of the operation of the gas engine control device according to the third embodiment of this disclosure.

[0025] Figure 10 This is a characteristic diagram showing the simulation results of an example of the operation of the gas engine control device according to the third embodiment of this disclosure.

[0026] Figure 11 This is a schematic block diagram illustrating the structure of a computer according to at least one embodiment. Detailed Implementation

[0027] <First Implementation Method>

[0028] Below, refer to Figures 1-4 The gas engine control device (engine control device), gas engine control method (engine control method), and program according to the first embodiment of this disclosure will be described. It should be noted that the same or corresponding structures are referred to by the same reference numerals in the various figures, and descriptions are appropriately omitted.

[0029] (Engine structure)

[0030] Figure 1 This is a schematic structural diagram of engine 1 according to at least one embodiment of the present disclosure. Engine 1 is a gas-fired engine that uses fuel gas as fuel, such as a generator engine that outputs power to a generator (not shown) used for generating electricity in a generator set or the like. Furthermore, Figure 1 The engine 1 shown is a gas combustion engine capable of generating a mixture by mixing fuel gas with intake air (air) through combustion, thereby outputting power. Engine 1 is a so-called premixed internal combustion engine that generates a mixture by premixing fuel gas supplied from a gas flow regulating valve 18 and intake air taken in from the outside on an upstream side of the combustion chamber 8, and draws the mixture into the combustion chamber 8 through an intake pipe 18 of a predetermined length.

[0031] When engine 1 is used as a generator engine, for example, as the power source for a generator in a generator set, combustion control and air-fuel ratio control are mainly performed on engine 1. In combustion control, in order to keep the output speed and load of engine 1 constant, feedback control is performed with output speed or load as the control variable and fuel gas supply as the operating variable. On the other hand, in air-fuel ratio control, in order to keep the air-fuel ratio in combustion chamber 8 constant, feedback control is performed indirectly with air-fuel ratio as the control variable and directly with the pressure or air-fuel mixture flow rate of intake manifold 11 as the control variable. This adjusts the opening of the throttle valve 14 located in front of intake manifold 11 or the opening of the exhaust bypass valve 26 located in exhaust bypass passage 25 as the operating variable.

[0032] Figure 1 The engine 1 shown has at least one cylinder 10. In this embodiment, the engine 1 has multiple cylinders 10, but... Figure 1 This design represents only one cylinder 10 for ease of understanding. Cylinder 10 includes a cylinder barrel 3 integrally formed with a cylinder block 13 and a piston 2 configured to reciprocate within the cylinder barrel. The engine 1 has an intake port 5, opened and closed by an intake valve 4, and an exhaust port 7, opened and closed by an exhaust valve 6, connected to the cylinder barrel 3, on which the piston 2 slides internally. A combustion chamber 8 is formed between the cylinder barrel 3 and the piston 2, and a spark plug 9 is disposed in the combustion chamber 8.

[0033] An intake manifold 11 is connected to the intake port 5. A throttle valve 14 is connected to the upper end of the intake manifold 11. A compressor 12c of a turbocharger 12 is connected to the intake pipe 16 further upstream. An intercooler 15 is connected to the middle section of the intake manifold 11. A gas flow regulating valve 18 for supplying fuel gas is connected to the mixer 56, which is connected to the middle section of the intake pipe 17 connected to the compressor 12c. An air filter 19 is connected upstream of the mixer 56. An intake manifold pressure sensor 60 and an intake manifold temperature sensor 62 are installed on the intake pipe 16 (or intake manifold 11) to measure the pressure and temperature of the mixture flowing in the intake pipe 16 (or the intake manifold 11), respectively. The detection values ​​of the intake manifold pressure sensor 60 and the intake manifold temperature sensor 62 are input as electrical signals to the gas engine control unit 100.

[0034] In mixer 56, an air-fuel mixture is generated by mixing intake air (outside air) and fuel gas. The air-fuel mixture generated by mixer 56 is supplied to intake port 5 via intake pipe 16. The flow rate of the air-fuel mixture supplied to intake port 5 is adjusted by controlling the opening of throttle valve 14.

[0035] On the other hand, an exhaust manifold 22 is connected to the exhaust port 7, and a turbine 12t of a turbocharger 12 is connected to its downstream end. The compressor 12c of the turbocharger 12 and the turbine 12t rotate as a unit via a rotating shaft 12s. An exhaust pipe 24 is connected to the turbine 12t, and an exhaust bypass valve 26 is provided on the exhaust bypass passage 25 connecting the exhaust pipe 24 and the exhaust manifold 22. An exhaust temperature sensor 64 is provided on the exhaust manifold 22 to measure the temperature of the exhaust gas flowing within the exhaust manifold 22. The detection value of the exhaust temperature sensor 64 is input as an electrical signal to the gas engine control unit 100. It should be noted that the exhaust temperature sensor 64 is provided for each cylinder 10.

[0036] Additionally, a secondary combustion chamber connector 48 with a secondary combustion chamber 46 is provided on the cylinder block 13. Multiple nozzles (not shown) for injecting flames into the combustion chamber 8 are formed around the front end of the secondary combustion chamber connector 48. Fuel gas is supplied to the secondary combustion chamber 46 via a secondary fuel gas supply line 52, and a flame is formed by a spark plug 9 located within the secondary combustion chamber 46. By blowing the flame formed within the secondary combustion chamber 46 out of the nozzles in a torch shape into the combustion chamber 8, effective combustion occurs over a wide area of ​​the combustion chamber 8. It should be noted that an adjusting valve 54 for adjusting the amount of fuel gas supplied relative to the secondary combustion chamber 46 is provided on the secondary fuel gas supply line 52.

[0037] In the engine 1 configured as described above, air drawn in from the air filter 19 is injected with fuel gas in the mixer 56 via the gas flow regulating valve 18 to form a mixture (fuel mixture). This mixture is compressed by the compressor 12c of the turbocharger 12, and then pressurized towards the cylinder 3 through the throttle valve 14 and intake manifold 11 to actuate the engine 1. The mixture is cooled by the intercooler 15 to reduce the heat of compression, and the flow rate is adjusted by regulating the opening of the throttle valve 14.

[0038] Furthermore, the exhaust gas discharged from cylinder 3 is supplied to the turbine 12t of turbocharger 12 via exhaust manifold 22, causing turbine 12t to rotate at high speed. This rotation drives compressor 12c at high speed via rotating shaft 12s, continuing the compression and boosting of fresh air. Additionally, by adjusting the opening of exhaust bypass valve 26 provided in exhaust bypass passage 25, the flow rate of exhaust gas flowing in turbine 12t is adjusted, thereby adjusting the air compression in compressor 12c. Therefore, by controlling the opening of exhaust bypass valve 26, the flow rate of the air-fuel mixture supplied to intake port 5 can be regulated.

[0039] The gas engine control unit (engine control unit) 100 is connected to the gas flow regulating valve 18, throttle valve 14, exhaust bypass valve 26, intake manifold pressure sensor 60, intake manifold temperature sensor 62, exhaust temperature sensor 64, and engine speed sensor 66 connected to the crankshaft (not shown), etc., to acquire the detection values ​​of each sensor and control the throttle valve 14, exhaust bypass valve 26, etc.

[0040] (Structure of the gas engine control unit)

[0041] The gas engine control unit 100 internally includes a computer and peripheral circuits or peripheral devices of the computer. As a functional structure composed of hardware such as the computer and peripheral circuits or peripheral devices, and software such as programs executed by the computer, it possesses... Figure 2 The exhaust temperature correction control unit 110 and air-fuel ratio control unit 120 are shown. The exhaust temperature correction control unit 110 includes an exhaust temperature calculation unit 111, an exhaust temperature averaging unit 112, an adder 113, a volumetric efficiency degradation calculation unit 114, a degradation retention determination unit 115, and an intake manifold pressure target correction calculation unit 116. The air-fuel ratio control unit 120 includes an adder 121, a MAP feedback control unit 122, a corrected air-fuel ratio target value calculation unit 123, a mixture flow rate target value calculation unit 124, a mixture flow rate calculation unit 125, an adder 126, and a valve opening command value calculation unit 127. Figure 2 This is a block diagram illustrating a structural example of the gas engine control device 100 according to the first embodiment of this disclosure. It should be noted that the gas engine control device 100 of this embodiment can perform both combustion control and air-fuel ratio control, but... Figure 2 Only the functional structure related to air-fuel ratio control is shown.

[0042] It should be noted that in the air-fuel ratio control of this embodiment, the influence of the change of fuel LHV (Lower Heating Value) on the change of theoretical air-fuel ratio is considered, the target value of the pressure of intake manifold 11 (hereinafter also referred to as intake manifold pressure (MAP)) is determined, and the intake manifold pressure (MAP) is controlled by feedback (MAP feedback control), thereby controlling the air-fuel ratio to the target value.

[0043] The exhaust temperature calculation unit 111 calculates the exhaust temperature (reference value) based on the control values ​​of the engine 1 at the reference volumetric efficiency. The exhaust temperature calculation value Tex_cal is expressed by the following formula.

[0044] [Mathematical Expression 1]

[0045]

[0046] Here, Cps is the intake specific heat at constant pressure, Cpex is the exhaust specific heat at constant pressure, MAT is the intake manifold temperature (temperature of intake manifold 11), Qex is the total calorific value, and Gmix is ​​the air-fuel mixture flow rate. Additionally, the total calorific value Qex is calculated using one of the following two formulas.

[0047] [Mathematical Expression 2]

[0048] (⑴)Qex=(electricity generated)×(1-th-ηhl)

[0049] [Mathematical Expression 3]

[0050] (2)Qex=LHV×Ggas×(1-·rnth-nhl)

[0051] Here, LHV is the lower heating value of the fuel, ηth is the power generation efficiency, ηhl is the heat loss, and Ggas is the fuel gas flow rate.

[0052] It should be noted that equation (1) is suitable for this control system because it is not easily affected by changes in LHV or load.

[0053] The exhaust temperature averaging processing unit 112 calculates the average exhaust temperature Tex_ave based on the exhaust temperature values ​​acquired from each exhaust temperature sensor 64 of each cylinder 10. The exhaust temperature sensor values ​​deviate for every 10 cylinders. Furthermore, because the difference with other cylinders increases significantly when there is no ignition, a proper average cannot be calculated; therefore, the average value is calculated after removing the maximum and minimum values ​​acquired by the sensors. This average value represents the current exhaust temperature.

[0054] Adder 113 calculates the deviation ΔTex between the calculated exhaust temperature value Tex_cal and the average exhaust temperature value Tex_ave (called exhaust temperature deviation).

[0055] The volumetric efficiency degradation calculation unit 114 calculates the volumetric efficiency degradation degree based on the exhaust temperature deviation ΔTex and the load of engine 1. The volumetric efficiency degradation degree can be calculated, for example, by mapping with the load and exhaust temperature deviation ΔTex as inputs. The volumetric efficiency degradation degree is a value (e.g., a value of 0 to 1 (0% to 100%)) representing the degree (proportion) of degradation, with the condition of no degradation set to, for example, 1 (=100%).

[0056] In the engine control of this embodiment, in combustion control, feedback control is performed with output speed or load as the control variable and fuel gas supply as the operating variable in order to keep the output speed and load of engine 1 constant. In this case, when the volumetric efficiency decreases, the amount of air-fuel mixture in the cylinder decreases. Therefore, in order to maintain output, excessive fuel is supplied in combustion control, resulting in an increase in exhaust temperature. Therefore, in the engine control of this embodiment, a constant correlation is generated between exhaust temperature deviation ΔTex and volumetric efficiency degradation. However, for example, even for the same volumetric efficiency degradation, there is a deviation such as ΔTex being about 20 to 30°C when the load is 100% and ΔTex being about 10 to 20°C when the load is 50 to 70%. It is necessary to calculate the volumetric efficiency degradation considering this. Therefore, in this embodiment, the volumetric efficiency degradation is calculated based on the exhaust temperature deviation ΔTex and the load of engine 1.

[0057] The degradation degree retention determination unit 115 maintains the calculated degradation degree in transitional states such as load connection or load disconnection, or in abnormal states such as sensor malfunction, thereby stabilizing the volumetric efficiency degradation degree. The degradation degree retention determination unit 115 is input with signals indicating whether it is in a transitional state or an abnormal state. If it is not in a transitional or abnormal state, it directly outputs the input exhaust temperature deviation ΔTex. If it is in a transitional or abnormal state, it maintains the output of the exhaust temperature deviation ΔTex that was input before the transitional or abnormal state occurred. It should be noted that a transitional state includes situations where the load increases by a predetermined value or more, and situations where the load decreases by a predetermined value or more. Furthermore, an abnormal state includes, for example, situations where the detection value of the exhaust temperature sensor 64 or the sensor used to measure the load is abnormal.

[0058] The intake manifold pressure target correction value calculation unit 116 calculates the correction value corresponding to the volumetric efficiency degradation degree relative to the target value in MAP feedback control. The intake manifold pressure target correction value calculation unit 116 calculates the correction value ΔMAP (intake manifold pressure target correction value) of the target value of the intake manifold pressure from the mapping based on the volumetric efficiency degradation degree and outputs it. The mapping for determining an appropriate intake manifold pressure target correction value ΔMAP value relative to the volumetric efficiency degradation degree can be determined based on simulation or actual measurement.

[0059] On the other hand, in the air-fuel ratio control unit 120, the adder 121 adds the target value of the intake manifold pressure (MAP) MAP_ref to the target value of the intake manifold pressure (MAP) for correction by adding the target correction value of the intake manifold pressure ΔMAP, and subtracts the measured value of the intake manifold pressure (MAP) (= the current value), calculates the deviation between "target value MAP_ref + target correction value of the intake manifold pressure ΔMAP" and the measured value MAP (= the current value of the intake manifold pressure) (= intake manifold pressure deviation) and outputs it.

[0060] The MAP feedback control unit 122 calculates the correction value of the target air-fuel ratio of the mixture, namely the air-fuel ratio target correction value Δλst, and outputs it as the operating quantity for feedback control based on the deviation between the target value MAP_ref of the intake manifold pressure obtained by correcting the target value MAP_ref of the intake manifold pressure from the target correction value ΔMAP and the current value MAP of the intake manifold pressure, namely the intake manifold pressure deviation. While the control action of the MAP feedback control unit 122 is not limited, it can be set to, for example, a PI (proportional-integral) action. The MAP feedback control unit 122 changes the air-fuel ratio target correction value Δλst in a manner that brings the intake manifold pressure deviation close to zero. The air-fuel ratio target correction value Δλst is a correction value used to match the current value MAP of the intake manifold pressure to the target value MAP_ref of the intake manifold pressure based on the volumetric efficiency degradation.

[0061] The modified air-fuel ratio target value calculation unit 123 is input with a modified air-fuel ratio target value Δλst and a stoichiometric air-fuel ratio (or target air-fuel ratio) λst, and outputs the modified air-fuel ratio target value obtained by modifying the stoichiometric air-fuel ratio (or target air-fuel ratio) λst by the modified air-fuel ratio target value Δλst. For example, the modified air-fuel ratio target value calculation unit 123 uses a mapping and calculation formula that uses the modified air-fuel ratio target value Δλst and the stoichiometric air-fuel ratio (or target air-fuel ratio) λst as parameters to calculate the modified air-fuel ratio target value. These mappings and calculation formulas can be determined based on simulation or actual measurement.

[0062] The mixture flow target value calculation unit 124 calculates the mixture flow target value Qmix_ref based on the theoretical air-fuel ratio (or target air-fuel ratio) λst (=corrected air-fuel ratio target value) corrected by the air-fuel ratio target correction value Δλst. The mixture flow target value Qmix_ref is a target value for obtaining the mixture flow rate of the theoretical air-fuel ratio (or target air-fuel ratio) λst corrected by the air-fuel ratio target correction value Δλst. The mixture flow target value calculation unit 124 calculates the mixture flow target value Qmix_ref with engine speed, intake manifold pressure MAP, intake manifold temperature MAT, etc., as input variables, and with total engine displacement, atmospheric pressure, etc., as constants.

[0063] In addition, the gas mixture flow calculation unit 125 calculates the current gas mixture flow rate Qmix using the following formula.

[0064] [Mathematical Expression 4]

[0065]

[0066] Here, Qmix is ​​the air-fuel mixture flow rate [L / sec], Ne is the engine speed [min⁻¹], V is the total engine displacement [L], ηv is the baseline volumetric efficiency [⁻¹], MAP is the intake manifold pressure [Pa], MAT is the intake manifold temperature [K], Tk is the absolute temperature [K], and Patm is the atmospheric pressure [Pa].

[0067] Adder 126 subtracts the gas mixture flow rate Qmix from the target gas mixture flow rate Qmix_ref, and calculates the deviation between the target gas mixture flow rate Qmix_ref and the gas mixture flow rate Qmix (gas mixture flow rate deviation).

[0068] The valve opening command value calculation unit 127 calculates the opening command value (valve opening command value) of the throttle valve 14 or the exhaust bypass valve 26 (collectively referred to as the valve that adjusts the flow rate of the mixture) based on the deviation (mixture flow rate deviation) between the target value of the mixture flow rate Qmix_ref and the current value of the mixture flow rate (Qmix). The valve opening command value calculation unit 127 may be, for example, a component that calculates either the valve opening command value of the throttle valve 14 or the valve opening command value of the exhaust bypass valve 26 and outputs it, or a component that calculates both and outputs them, or a component that selectively calculates one of them and outputs it based on conditions.

[0069] (Example of the operation of a gas engine control device)

[0070] Reference Figure 3 right Figure 2 The operation of the gas engine control device 100 shown will be explained using an example. Figure 3 This is a flowchart illustrating an example of the operation of the gas engine control device according to the first embodiment of this disclosure. It is executed repeatedly at a predetermined cycle. Figure 3 The processing shown.

[0071] When it begins Figure 3In the processing described, firstly, the exhaust temperature calculation unit 111 calculates the exhaust temperature calculation value Tex_cal (step S11). Next, the exhaust temperature averaging processing unit 112 performs exhaust temperature averaging processing and calculates the exhaust temperature average value Tex_ave (step S12). Next, the adder 113 calculates the exhaust temperature deviation ΔTex between the exhaust temperature calculation value Tex_cal and the exhaust temperature average value Tex_ave (step S13). Next, the volumetric efficiency degradation calculation unit 114 calculates the volumetric efficiency degradation (step S14). Next, the degradation degree retention determination unit 115 determines whether to retain the degradation degree (step S15). If it is retained (in the case of "retain" in step S15), the volumetric efficiency degradation degree is retained at the value before the change (step S16). If it is not retained (in the case of "update" in step S15), the volumetric efficiency degradation degree is updated with the value calculated in step S14 (step S17). Next, the intake manifold pressure target correction value calculation unit 116 calculates the intake manifold target correction value ΔMAP (step S18).

[0072] Next, adder 121 calculates the intake manifold pressure deviation (step S19). Next, MAP feedback control unit 122 calculates the air-fuel ratio target correction value Δλst (step S20). Next, the corrected air-fuel ratio target value calculation unit 123 calculates the theoretical air-fuel ratio (or target air-fuel ratio) λst based on the corrected air-fuel ratio target correction value Δλst, and the mixture flow target value calculation unit 124 calculates the mixture flow target value Qmix_ref (step S21). Next, the mixture flow calculation unit 125 calculates the mixture flow Qmix (step S22). Next, adder 126 calculates the mixture flow deviation (step S23). Next, valve opening command value calculation unit 127 calculates the valve opening command value and outputs it to throttle valve 14 or exhaust bypass valve 26 (step S24), ending the process. Figure 3 The processing shown.

[0073] In the above processing, when the volumetric efficiency deteriorates significantly, the target MAP is increased by adding the target intake manifold pressure correction value ΔMAP to the target MAP_ref. Therefore, for example, when controlling the throttle valve 14, the air volume can be increased because the throttle valve opening moves towards the open side. When the volumetric efficiency decreases, without the exhaust temperature correction control of this embodiment, the air-fuel ratio λ is corrected from rich to lean in this embodiment, which can suppress NOx emissions.

[0074] (The function / effect of this implementation method)

[0075] According to this embodiment, a decrease in volumetric efficiency can be detected based on the deviation between the value obtained and the calculated value from the exhaust temperature sensor. Furthermore, according to this embodiment, feedback control can be performed using the exhaust temperature before deterioration as a target value (reference value), and corrective control of the air supply volume can be implemented. Additionally, when volumetric efficiency decreases, air supply volume can be increased to control the air-fuel ratio when it is lean, thereby suppressing NOx emissions. Moreover, according to this embodiment, since the intake manifold pressure target value is corrected when exhaust temperature rises due to volumetric efficiency deterioration, deterioration detection and correction can be performed through exhaust temperature monitoring.

[0076] Furthermore, in this embodiment, since the correction value in engine control can be calculated in normal control, the correction value in engine control can be easily calculated without being limited by forced increases / decreases in operation amount, etc.

[0077] (Simulation Results)

[0078] Figure 4 This is a characteristic graph showing the simulation results of an operation example of the gas engine control device according to the first embodiment of this disclosure. The horizontal axis represents the degree of volumetric efficiency degradation, and the vertical axis represents the air-fuel ratio λ. The simulation results confirm that, without the exhaust temperature correction control of this embodiment, the air-fuel ratio λ becomes richer relative to the degradation of volumetric efficiency. However, by incorporating the exhaust temperature correction control of this embodiment, the air-fuel ratio λ can be corrected to lean. That is, based on these simulation results, the NOx emission suppression effect of this embodiment can be confirmed.

[0079] <Second Implementation Method>

[0080] Next, refer to Figures 5-7 The gas engine control device (engine control device), gas engine control method (engine control method), and procedure of the second embodiment of this disclosure will be described. Figure 5 This is a block diagram illustrating a structural example of a gas engine control device according to the second embodiment of this disclosure. Figure 6 This is a flowchart illustrating an example of the operation of the gas engine control device according to the second embodiment of this disclosure. Figure 7 This is a characteristic diagram showing the simulation results of an example of the operation of the gas engine control device according to the second embodiment of this disclosure.

[0081] Figure 5 The gas engine control device 100a of the second embodiment shown is compared with the reference. Figure 1 and Figure 2 Compared to the gas engine control device 100 of the first embodiment described herein, there are the following differences. That is, compared to... Figure 2 The exhaust temperature correction control unit 110 shown corresponds to Figure 5 The exhaust temperature correction control unit 110a shown is Figure 2 Compared to the exhaust temperature correction control unit 110 shown, the volumetric efficiency degradation degree output by the degradation degree retention determination unit 115 is directed towards... Figure 2 The air-fuel ratio control unit 120 shown corresponds to Figure 5 The air-fuel ratio control unit 120a shown differs in this respect. Additionally, Figure 5 The air-fuel ratio control unit 120a shown is Figure 2 Compared to the air-fuel ratio control unit 120 shown, the new addition includes a volume efficiency correction value calculation unit 128, which is similar to... Figure 2 The mixed gas flow calculation unit 125 shown corresponds to Figure 5 The difference is that the mixed gas flow calculation unit 125a shown uses a different calculation formula to calculate the mixed gas flow rate Qmix than in the first embodiment.

[0082] The volumetric efficiency correction value calculation unit 128 calculates the volumetric efficiency correction value Δηv based on the volumetric efficiency degradation degree. Here, the volumetric efficiency correction value calculation unit 128 calculates the volumetric efficiency correction value Δηv to have a correction margin equal to the intake manifold pressure target correction value ΔMAP calculated by the intake manifold pressure target correction value calculation unit 116 based on the volumetric efficiency degradation degree. That is, the increase ratio of air volume based on the correction amount for intake manifold pressure (intake manifold pressure target correction value ΔMAP) and the correction amount for volumetric efficiency (volumetric efficiency correction value Δηv) are equal. For example, when the intake manifold pressure is set to 300 kPa at 100% load, the intake manifold pressure target correction value ΔMAP is corrected by 6 kPa for every 10°C exhaust temperature deviation ΔTex, which is equivalent to increasing the air volume by 2%. In this case, the volumetric efficiency correction amount Δηv is also calculated in the same way, increasing the air volume by 2% for every 10°C exhaust temperature deviation ΔTex. Therefore, in this embodiment, the decrease in stability caused by combining the two modifications is prevented.

[0083] In addition, the mixed gas flow calculation unit 125a calculates the mixed gas flow rate Qmix using the following formula.

[0084] [Mathematical Expression 5]

[0085]

[0086] The gas-mix flow rate calculation unit 125a calculates the gas-mix flow rate Qmix using the newly calculated volumetric efficiency correction value Δηv from the volumetric efficiency correction value calculation unit 128. In this case, the gas-mix flow rate calculation unit 125a multiplies the volumetric efficiency correction value Δηv by the gas-mix flow rate Qmix calculated in the first embodiment.

[0087] It should be noted that, in the second embodiment, when the exhaust temperature calculation unit 111 calculates the exhaust temperature, the mixed gas flow rate Gmix in the exhaust temperature calculation formula is obtained using the value before volumetric efficiency correction. In the second embodiment, assuming the degree of volumetric efficiency degradation or the deviation of each correction value from the baseline volumetric efficiency, it is necessary to calculate the exhaust temperature based on the mixed gas flow rate Gmix before correction.

[0088] In the second embodiment, a correction based on the volumetric efficiency degradation is performed by adding the intake manifold target value to the correction value ΔMAP relative to the intake manifold pressure target value. In addition, a correction based on the volumetric efficiency degradation is performed by multiplying the volumetric efficiency correction value Δηv by the mixture flow rate Qmix calculated value.

[0089] According to this structure, when controlling, for example, the throttle valve 14 by increasing the target MAP, the throttle valve opening moves towards the open side. Furthermore, the air-fuel mixture flow rate, after correcting for volumetric efficiency, becomes a value that takes into account years of degradation, increasing the deviation from the target air-fuel mixture flow rate value. That is, if the volumetric efficiency correction value calculated by the air-fuel mixture flow rate calculation unit 125a based on the volumetric efficiency degradation is multiplied by the original air-fuel mixture flow rate, the corrected air-fuel mixture flow rate decreases, thus increasing the air-fuel mixture flow rate deviation. For example, when controlling the throttle valve 14, the throttle valve opens and the air-fuel mixture increases. As a result, the increased air-fuel mixture corrects the air-fuel ratio λ from rich to lean when volumetric efficiency decreases, suppressing NOx emissions.

[0090] It should be noted that, Figure 6 The processing shown is the same as Figure 3 The following points differ from the processing shown. Specifically, the addition of step S21-1 after step S21 is different. In this step S21-1, the volumetric efficiency correction calculation unit 128 calculates the volumetric efficiency correction value Δηv. Furthermore, in comparison with... Figure 3 The difference between step S22a and step S222 is that the gas mixture flow calculation unit 125a uses the volumetric efficiency correction value Δηv calculated by the volumetric efficiency correction value calculation unit 128 to calculate the gas mixture flow rate Qmix. All other processes are the same.

[0091] In the second embodiment, by correcting the volumetric efficiency, the correct air-fuel mixture volume that takes into account the deterioration can be calculated, thus improving control accuracy. Furthermore, when volumetric efficiency decreases, by increasing the air volume, air-fuel ratio control can be performed when the air-fuel ratio λ is lean, thereby suppressing NOx emissions.

[0092] It should be noted that, as Figure 7As shown, the simulation results of the second embodiment confirm that the air-fuel ratio λ lean effect is the same as that of the first embodiment when both the intake manifold pressure target value correction and the mixture flow calculation correction are performed.

[0093] <Third Implementation Method>

[0094] Next, refer to Figures 8-10 The gas engine control device (engine control device), gas engine control method (engine control method), and procedure of the third embodiment of this disclosure will be described. Figure 8 This is a block diagram illustrating a structural example of a gas engine control device according to the third embodiment of this disclosure. Figure 9 This is a flowchart illustrating an example of the operation of the gas engine control device according to the third embodiment of this disclosure. Figure 10 This is a characteristic diagram showing the simulation results of an example of the operation of the gas engine control device according to the third embodiment of this disclosure.

[0095] Figure 8 The gas engine control device 100b of the third embodiment shown is compared with the reference. Figure 5 Compared to the gas engine control device 100a of the second embodiment described above, it has the following differences. That is, compared to... Figure 5 The exhaust temperature correction control unit 110a shown corresponds to Figure 8 The exhaust temperature correction control unit 110b shown omits the following: Figure 5 This differs from the intake manifold pressure target correction value calculation unit 116 shown. Additionally, in relation to... Figure 5 The air-fuel ratio control unit 120a shown corresponds to Figure 8 The air-fuel ratio control unit 120b shown omits [the following]. Figure 5 The adder 121, MAP feedback control unit 122, and corrected air-fuel ratio target value calculation unit 123 shown here are different from the mixture flow target value calculation unit 124 in that it calculates the mixture flow target value Qmix_ref based on the theoretical air-fuel ratio (target air-fuel ratio) λst.

[0096] In the gas engine control device 100b of the third embodiment, the MAP feedback control function is disabled. In the third embodiment, by correcting the volumetric efficiency, the air-fuel mixture flow rate becomes a value that takes into account years of degradation, increasing the deviation from the target air-fuel mixture flow rate value. As a result, for example, when the throttle valve 14 is controlled, the throttle valve moves to the open side, increasing the air-fuel mixture flow rate. When the volumetric efficiency decreases, the air-fuel ratio λ is corrected from being rich to lean, thus suppressing NOx emissions.

[0097] It should be noted that, Figure 9 The processing shown is the same as Figure 6The difference between this and the previous process is that steps S18 to S20 are omitted. Additionally, as shown... Figure 10 As shown, simulation results from the third embodiment confirm that even when MAP feedback control is disabled, a lean air-fuel ratio λ is achieved by correcting for volumetric efficiency through annual degradation relative to volumetric efficiency.

[0098] (Other implementation methods)

[0099] As described above, embodiments of the present disclosure have been described in detail with reference to the accompanying drawings. However, the specific structure is not limited to the present embodiments and may include design changes that do not depart from the scope of the present disclosure.

[0100] Computer Architecture

[0101] Figure 11 This is a schematic block diagram illustrating the structure of a computer according to at least one embodiment.

[0102] Computer 90 has a processor 91, main memory 92, memory 93 and interface 94.

[0103] The aforementioned gas engine control devices 100, 100a, and 100b are installed in the computer 90. Furthermore, the operations of each of the aforementioned processing units are stored in the memory 93 as programs. The processor 91 reads the program from the memory 93, expands it in the main memory 92, and executes the aforementioned processing according to the program. Additionally, the processor 91 secures the corresponding storage area in the main memory 92 according to the program for each of the aforementioned storage units.

[0104] The program can also be used to implement a portion of the functions performed by the computer 90. For example, the program can also function by combining with other programs already stored in memory or with other programs installed on other devices. It should be noted that in other embodiments, in addition to the above-described structure, the computer may also possess a custom LSI (Large Scale Integrated Circuit) such as a PLD (Programmable Logic Device) to replace the above structure. Examples of PLDs include PAL (Programmable Array Logic), GAL (Generic Array Logic), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Array). In this case, some or all of the functions implemented by the processor can be implemented by this integrated circuit.

[0105] Examples of memory 93 include HDD (Hard Disk Drive), SSD (Solid State Drive), magnetic disk, optical disk, CD-ROM (Compact Disc Read Only Memory), DVD-ROM (Digital Versatile Disc Read Only Memory), and semiconductor memory. Memory 93 can be an internal medium directly connected to the bus of computer 90, or an external medium connected to computer 90 via interface 94 or a communication line. Furthermore, when the program is sent to computer 90 via a communication line, computer 90, upon receiving the program, can also open the program in main memory 92 and execute the aforementioned processing. In at least one embodiment, memory 93 is a non-temporary tangible storage medium.

[0106] <Note>

[0107] For example, the gas engine control devices 100, 100a and 100b described in each embodiment are as follows.

[0108] (1) A first method provides an engine control device (gas engine control devices 100, 100a, and 100b), wherein, when controlling the opening of a valve (throttle valve 14 or exhaust bypass valve 26) that adjusts the intake amount of the air-fuel mixture of engine 1, the opening is corrected based on the deviation between a reference value Tex_cal and the current value Tex_ave of the exhaust temperature, i.e., the exhaust temperature deviation ΔTex. According to this method and the following methods, since the correction value in engine control can be calculated in normal control, the correction value in engine control can be easily calculated without being limited by forced increases / decreases in operating amounts, etc.

[0109] (2) The second type of engine control device (gas engine control device 100, 100a and 100b) is based on the engine control device of (1), wherein the opening of the valve (throttle valve 14 or exhaust bypass valve 26) is controlled in order to control the air-fuel ratio λ of the mixture to a specified value.

[0110] (3) A third-party engine control unit (gas engine control unit 100, 100a and 100b) is based on the engine control unit of (1) or (2), wherein it has a volumetric efficiency degradation calculation unit 114, which calculates the volumetric efficiency degradation based on the exhaust temperature deviation ΔTex and the load of engine 1, and corrects the opening of the valve (throttle valve 14 or exhaust bypass valve 26) based on the volumetric efficiency degradation.

[0111] (4) The fourth type of engine control device (gas engine control devices 100, 100a and 100b) is based on the engine control device of (3), wherein it further includes a degradation degree retention determination unit 115, which determines whether the load changes, and retains the volumetric efficiency degradation degree as before the change when the load changes. According to this method, the volumetric degradation degree can be calculated stably.

[0112] (5) The fifth type of engine control device (gas engine control device 100 and 100a) is an engine control device according to (3) or (4), wherein it includes: an intake manifold pressure target correction value calculation unit 116, which calculates the correction value of the target value of the pressure of the intake manifold 11 of the engine 1 (hereinafter referred to as intake manifold pressure) based on the volume efficiency degradation degree, namely the intake manifold pressure target correction value ΔMAP; and an intake manifold pressure feedback control unit (MAP feedback control unit 122), which calculates the correction value of the target value of the air-fuel ratio of the mixture, namely the air-fuel ratio target correction value Δλst, and uses it as the basis for the intake manifold pressure target correction value. The deviation between the target value ΔMAP of the intake manifold pressure and the current value MAP of the intake manifold pressure is the operating quantity of the intake manifold pressure deviation feedback control; the mixture flow target value calculation unit 124 calculates the mixture flow target value Qmix_ref based on the value obtained by correcting the target value of the air-fuel ratio from the air-fuel ratio target correction value; the valve opening command value calculation unit 127 calculates the valve (throttle valve 14 or exhaust bypass valve 26) opening command value based on the deviation between the mixture flow target value Qmix_ref and the current value Qmix of the mixture flow.

[0113] (6) The sixth type of engine control device (gas engine control device 100a) is based on the engine control device of (5), wherein the current value of the flow rate of the mixture Qmix is ​​a value obtained by correcting the volumetric efficiency degradation.

[0114] (7) The engine control device of the seventh type (gas engine control device 100a and 100b) according to the engine control device of (3) or (4) includes: a mixture flow target value calculation unit 124, which calculates the mixture flow target value Qmix_ref; and a valve opening command value calculation unit 127, which calculates the valve (throttle valve 14 or exhaust bypass valve 26) opening command value based on the deviation between the mixture flow target value Qmix_ref and the current value Qmix of the mixture flow rate corrected according to the volume efficiency deterioration.

[0115] Industrial availability

[0116] According to various methods of the present invention, correction values ​​in engine control can be easily calculated.

[0117] Explanation of reference numerals in the attached figures

[0118] 1. Engine

[0119] 3 cylinders

[0120] 10 cylinders

[0121] 11. Intake Manifold

[0122] 12. Supercharger

[0123] 12C compressor

[0124] 12t turbine

[0125] 13 Cylinder Block

[0126] 14 Throttle body

[0127] 22 Exhaust Manifold

[0128] 24 Exhaust pipe

[0129] 25 Exhaust bypass passage

[0130] 26. Exhaust bypass valve

[0131] 60 Intake manifold pressure sensor

[0132] 62 Intake manifold temperature sensor

[0133] 64 Exhaust Temperature Sensor

[0134] 66 Engine speed sensor

[0135] 100 Gas Engine Control Unit (Engine Control Unit)

Claims

1. An engine control device, wherein, When controlling the valve opening to adjust the air-fuel mixture flow rate of the engine, the valve opening is corrected based on the deviation between the reference value and the current value of the exhaust temperature, i.e., the exhaust temperature deviation. It includes a volumetric efficiency degradation calculation unit that calculates the volumetric efficiency degradation based on the exhaust temperature deviation and the engine load. The opening degree is adjusted based on the aforementioned volumetric efficiency degradation. It also has a degradation degree retention determination unit, which determines whether the load changes, and if it changes, retains the volumetric efficiency degradation degree as before the change.

2. The engine control device according to claim 1, wherein, The valve opening is controlled in order to control the air-fuel ratio of the mixture to a specified value.

3. The engine control device according to claim 1 or 2, wherein, have: The intake manifold pressure target correction value calculation unit calculates the correction value of the target value of the engine's intake manifold pressure based on the volume efficiency degradation degree, which is the intake manifold pressure target correction value. The intake manifold pressure feedback control unit calculates a correction value for the target value of the air-fuel ratio of the mixture, namely the air-fuel ratio target correction value, and uses it as the operating quantity for feedback control of the deviation between the value obtained by correcting the target value of the intake manifold pressure based on the intake manifold pressure target correction value and the current value of the intake manifold pressure, namely the intake manifold pressure deviation. The mixture flow rate target value calculation unit calculates the mixture flow rate target value based on the value obtained by correcting the target value of the air-fuel ratio from the target correction value of the air-fuel ratio; The valve opening command value calculation unit calculates the valve opening command value based on the deviation between the target value of the air-fuel mixture flow rate and the current value of the air-fuel mixture flow rate.

4. The engine control device according to claim 3, wherein, The current value of the flow rate of the mixed gas is a value obtained by correcting for the volumetric efficiency degradation.

5. The engine control device according to claim 1 or 2, wherein, have: The target value calculation unit for the mixed gas flow rate calculates the target value for the mixed gas flow rate. The valve opening command value calculation unit calculates the valve opening command value based on the deviation between the target value of the air-fuel mixture flow rate and the current value of the air-fuel mixture flow rate obtained by correcting the volumetric efficiency degradation.

6. An engine control method, comprising the following steps: When controlling the valve opening to adjust the air-fuel mixture flow rate of the engine, the valve opening is corrected based on the deviation between the reference value and the current value of the exhaust temperature, i.e., the exhaust temperature deviation. The volumetric efficiency degradation is calculated based on the exhaust temperature deviation and the engine load. The opening degree is adjusted based on the aforementioned volumetric efficiency degradation. Determine whether the load has changed, and if it has changed, maintain the volumetric efficiency degradation at the value before the change.

7. A program product that causes a computer to perform the following steps: When controlling the valve opening to adjust the air-fuel mixture flow rate of the engine, the valve opening is corrected based on the deviation between the reference value and the current value of the exhaust temperature, i.e., the exhaust temperature deviation. The volumetric efficiency degradation is calculated based on the exhaust temperature deviation and the engine load. The opening degree is adjusted based on the aforementioned volumetric efficiency degradation. Determine whether the load has changed, and if it has changed, maintain the volumetric efficiency degradation at the value before the change.

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