A method and device for controlling excess air coefficient of a natural gas engine

Abstract

The present invention discloses a method and device for controlling the excess air coefficient of a natural gas engine. The method comprises obtaining a current engine state signal, a cylinder pressure signal, and the actual excess air coefficient of the previous control cycle; determining the actual air volume based on the relationship between the current engine state signal and a signal threshold, the cylinder pressure signal, and the engine's operating state; and determining a target natural gas injection volume based on the actual air volume and the actual excess air coefficient of the previous control cycle; determining a target throttle opening based on an engine accelerator pedal signal; adjusting the target natural gas injection volume in real time based on the target natural gas injection volume, controlling natural gas combustion based on the real-time adjusted target natural gas injection volume and target throttle opening, and obtaining the actual excess air coefficient of the current control cycle in real time, ensuring that the difference between the actual excess air coefficient and the target excess air coefficient always remains within the threshold range. Using this method, precise control of the actual excess air coefficient is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of natural gas engines, and in particular to a method and device for controlling the excess air coefficient of a natural gas engine. Background Art

[0002] To meet emission standards, natural gas engines use stoichiometric combustion for engine control. The amount of natural gas injected per cycle is determined by the fresh air entering the cylinder. Due to the fluidity lag in the intake process of natural gas engines, precise control of the excess air ratio is challenging. This is particularly difficult during rapid engine acceleration or deceleration, leading to transient lean or rich burn conditions, which negatively impact natural gas emissions control.

[0003] Existing control of the excess air coefficient mainly calculates the amount of fresh air through the intake manifold. However, for natural gas engines with intake port injection, when the natural gas fuel amount is calculated using the collected intake manifold pressure, the piston in the cylinder has not yet reached the piston bottom dead center position. Therefore, the calculated natural gas injection amount is inaccurate, resulting in an increase in the transient excess air coefficient or the time for air-fuel ratio adjustment, reducing control efficiency. In addition, the engine's intake and rich combustion conditions are not distinguished, resulting in a decrease in the calculation accuracy of the excess air coefficient. Summary of the Invention

[0004] The present invention provides a method and device for controlling the excess air coefficient of a natural gas engine, which accurately determines the actual air volume according to the operating state of the engine, and accurately determines the target natural gas injection volume according to the actual air volume, thereby achieving precise regulation of the actual excess air coefficient, so that the actual excess air coefficient is always within a preset excess air coefficient threshold range, and improving the regulation accuracy and calculation efficiency of the actual excess air coefficient.

[0005] In a first aspect, the present invention provides a method for controlling excess air coefficient of a natural gas engine, characterized by comprising:

[0006] According to a preset cycle, within the current control cycle, the engine current state signal and cylinder pressure signal, as well as the actual excess air coefficient of the previous control cycle are obtained; the engine current state signal includes the engine accelerator pedal signal, the engine brake pedal signal and the engine speed signal;

[0007] Determine the target air volume according to the engine accelerator pedal signal, the engine speed signal and the cylinder pressure signal;

[0008] Determine the working state of the engine according to the relationship between the current state signal of the engine and the signal threshold, the working state of the engine including the steady state working state and the transient working state;

[0009] Determine the actual air volume based on the cylinder pressure signal and the engine's operating status;

[0010] Determine the target natural gas injection amount according to the actual air amount, the actual excess air coefficient of the previous control cycle, the target excess air coefficient, the engine speed signal and the air-fuel ratio;

[0011] Determine the target throttle opening according to the target air volume;

[0012] Based on the target natural gas injection amount, the target natural gas injection amount is adjusted in real time, and the target natural gas injection timing and target natural gas injection pulse width are determined according to the real-time adjusted target natural gas injection amount and the engine speed signal; and according to the target throttle opening, the target natural gas injection timing and the target natural gas injection pulse width, the natural gas combustion is controlled, and the actual excess air coefficient of the current control cycle is obtained in real time, so that the difference between the actual excess air coefficient of the current control cycle obtained in real time and the target excess air coefficient is within a preset excess air coefficient threshold range.

[0013] Optionally, the cylinder pressure signal includes an intake manifold pressure signal; determining the target air volume according to the engine accelerator pedal signal, the engine speed signal, and the cylinder pressure signal includes:

[0014] Obtain intake manifold temperature signal;

[0015] Determining the target torque based on a first correspondence according to the engine accelerator pedal signal; the first correspondence being a preset correspondence between the engine accelerator pedal signal and the target torque;

[0016] determining a target air charge according to the target torque and the engine speed signal based on a second correspondence relationship; the second correspondence relationship being a preset correspondence relationship among the target torque, the engine speed signal, and the target air charge;

[0017] determining an actual air charge according to the air mass under the intake manifold pressure signal and the intake manifold temperature signal and the air mass under a preset standard state;

[0018] determining a target air volume according to the target air volume and the actual air volume based on a first calculation formula;

[0019] The first calculation formula is: ;

[0020] in, is the target air volume, To target air charge, is the actual air charge, and is the charge adjustment coefficient, is the charge-to-flow coefficient.

[0021] Optionally, determining the operating state of the engine based on the relationship between the current engine state signal and the signal threshold includes:

[0022] When the engine accelerator pedal signal is greater than the accelerator pedal signal threshold, or the engine brake pedal signal is greater than the brake pedal signal threshold, determining that the engine is in a transient operating state;

[0023] When the engine accelerator pedal signal is less than the accelerator pedal signal threshold, or the engine brake pedal signal is less than the brake pedal signal threshold, it is determined that the engine is in a steady-state operating condition.

[0024] Optionally, the actual air volume is determined based on the cylinder pressure signal and the operating state of the engine, including:

[0025] Determine the air volume feedforward value based on the cylinder pressure signal; the cylinder pressure signal includes the intake manifold pressure signal, the gas partial pressure signal flowing through the EGR valve, the natural gas partial pressure signal, and the residual gas partial pressure signal;

[0026] When the engine is in a steady-state operating condition, a steady-state air volume compensation value is determined according to the engine speed signal and the intake manifold pressure signal;

[0027] When the engine is in transient working condition, the transient air volume compensation value is determined based on multiple cylinder pressure signals;

[0028] Determine the actual air volume according to the engine's operating state, the air volume feedforward value, the steady-state air volume compensation value, and the transient air volume compensation value;

[0029] Optionally, an air volume feedforward value is determined based on the cylinder pressure signal, including:

[0030] Determining an air volume feedforward value based on a second calculation formula according to the cylinder pressure signal;

[0031] The second calculation formula is: ;

[0032] in, is the air volume feedforward value, is the intake manifold pressure signal, is the gas partial pressure signal flowing through the EGR valve, is the natural gas partial pressure signal, is the residual gas partial pressure signal.

[0033] Optionally, when the engine is in a steady-state operating condition, the steady-state air volume compensation value is determined according to the engine speed signal and the intake manifold pressure signal, including:

[0034] When the engine is in a steady-state condition, the prediction time is determined based on the intake manifold pressure signal;

[0035] determining the air partial pressure of the intake manifold based on a third calculation formula according to the intake manifold pressure signal, the gas partial pressure signal flowing through the EGR valve, and the natural gas partial pressure signal;

[0036] Determining a steady-state air volume compensation value based on a fourth calculation formula according to the predicted time, the air partial pressure of the intake manifold, and the engine speed signal;

[0037] When the engine is in transient working condition, the transient air volume compensation value is determined based on multiple cylinder pressure signals, including:

[0038] When the engine is in a transient operating condition, determining the air partial pressures of the N intake manifolds based on the N intake manifold pressure signals, the gas partial pressure signal flowing through the EGR valve, and the natural gas partial pressure signal based on a third calculation formula;

[0039] Determining a transient air volume compensation value based on the fifth calculation formula according to the air partial pressures of the N intake manifolds;

[0040] The third calculation formula is: ; The fourth calculation formula is: ; The fifth calculation formula is: ;

[0041] in, is the steady-state air volume compensation value, is the intake manifold pressure signal, is the gas partial pressure signal flowing through the EGR valve, is the natural gas partial pressure signal, is the air partial pressure signal of the intake manifold, is the engine speed signal, It is the preset correspondence between the air partial pressure of the intake manifold and the engine speed signal. For the prediction time; is the transient air volume compensation value, 、 、 、 and is the air partial pressure of N intake manifolds, is the number of collections, The preset collection period.

[0042] Optionally, determining the actual air volume according to the engine operating state, the air volume feedforward value, the steady-state air volume compensation value, and the transient air volume compensation value includes:

[0043] When the engine is in steady-state operation, the actual air volume is determined based on the air volume feedforward value and the steady-state air volume compensation value; or,

[0044] When the engine is in transient operating conditions, the actual air volume is determined based on the air volume feedforward value and the transient air volume compensation value.

[0045] Optionally, the target natural gas injection amount is determined based on the actual air amount, the actual excess air coefficient of the previous control cycle, the target excess air coefficient, the engine speed signal, and the air-fuel ratio, including:

[0046] Determine the target natural gas feedforward value based on the sixth calculation formula according to the actual air quantity and air-fuel ratio;

[0047] determining a target natural gas compensation amount based on a seventh calculation formula according to a difference between an actual excess air coefficient and a target excess air coefficient in a previous control cycle and an engine speed signal;

[0048] determining a target natural gas injection amount according to a target natural gas feedforward value and a target natural gas compensation amount;

[0049] The sixth calculation formula is: , the seventh calculation formula is: ;

[0050] in, is the target natural gas feedforward value, is the actual air volume, is the air-fuel ratio, is the target natural gas compensation amount, is the difference between the actual excess air coefficient and the target excess air coefficient in the previous control cycle, is the engine speed signal, It is a preset correspondence between the engine speed signal and the difference.

[0051] Optionally, a target throttle opening is determined based on the target air volume, including:

[0052] Get the current ambient temperature, current ambient pressure, throttle inlet pressure and throttle outlet pressure;

[0053] According to the target air volume, the current ambient temperature, and the current ambient pressure, the target air volume is normalized based on an eighth calculation formula to determine a normalized target air volume;

[0054] determining a target throttle opening based on a third correspondence according to the standardized target air volume, the engine speed signal, the throttle inlet pressure, and the throttle outlet pressure;

[0055] The eighth calculation formula is: , the third corresponding relationship is: ;

[0056] in, is the standardized target air volume, is the target air volume, is the current ambient temperature, Due to the current environmental pressure, is the correction factor, is the target throttle opening, is the throttle outlet pressure, is the throttle inlet pressure, is the engine speed signal, It is a preset correspondence between the target throttle opening, the ratio of the throttle outlet pressure to the throttle inlet pressure and the engine speed signal.

[0057] In a second aspect, the present invention provides a control device for excess air coefficient of a natural gas engine, comprising:

[0058] A signal acquisition module is used to obtain the engine's current state signal and cylinder pressure signal, as well as the actual excess air coefficient of the previous control cycle, according to a preset period within the current control cycle; the engine's current state signal includes the engine accelerator pedal signal, the engine brake pedal signal, and the engine speed signal;

[0059] a target air volume determination module, configured to determine a target air volume based on an engine accelerator pedal signal, an engine speed signal, and a cylinder pressure signal;

[0060] A working state determination module is used to determine the working state of the engine according to the relationship between the current state signal of the engine and the signal threshold. The working state of the engine includes a steady state working state and a transient working state.

[0061] An actual air volume determination module is used to determine the actual air volume based on the cylinder pressure signal and the working state of the engine;

[0062] a target natural gas injection amount determination module, for determining the target natural gas injection amount based on the actual air amount, the actual excess air coefficient of the previous control cycle, the target excess air coefficient, the engine speed signal, and the air-fuel ratio;

[0063] A target throttle opening determination module is used to determine a target throttle opening according to a target air volume;

[0064] The real-time control module is used to adjust the target natural gas injection amount in real time based on the target natural gas injection amount, and determine the target natural gas injection timing and target natural gas injection pulse width based on the real-time adjusted target natural gas injection amount and the engine speed signal; and control the natural gas combustion based on the target throttle opening, the target natural gas injection timing and the target natural gas injection pulse width, and obtain the actual excess air coefficient of the current control cycle in real time, so that the difference between the actual excess air coefficient of the current control cycle obtained in real time and the target excess air coefficient is within a preset excess air coefficient threshold range.

[0065] The technical solution of the present invention is to obtain the current state signal of the engine and the cylinder pressure signal, as well as the actual excess air coefficient of the previous control cycle in accordance with a preset cycle within the current control cycle; determine the target air volume according to the engine throttle pedal signal, the engine speed signal and the cylinder pressure signal; determine the working state of the engine according to the relationship between the current state signal of the engine and the signal threshold, the working state of the engine including steady-state working state and transient working state; determine the actual air volume according to the cylinder pressure signal and the working state of the engine; determine the actual air volume according to the actual air volume, the actual excess air coefficient of the previous control cycle, the target excess air coefficient, the engine speed signal and The air-fuel ratio is used to determine the target natural gas injection quantity; the target throttle opening is determined based on the target air quantity; based on the target natural gas injection quantity, the target natural gas injection quantity is adjusted in real time, and the target natural gas injection timing and target natural gas injection pulse width are determined based on the real-time adjusted target natural gas injection quantity and the engine speed signal; and the natural gas combustion is controlled based on the target throttle opening, the target natural gas injection timing, and the target natural gas injection pulse width, and the actual excess air coefficient of the current control cycle is obtained in real time, so that the difference between the actual excess air coefficient of the current control cycle obtained in real time and the target excess air coefficient is within a preset excess air coefficient threshold range. Utilizing the above method, the actual air quantity is accurately determined based on the operating state of the engine, and the target natural gas injection quantity is precisely determined based on the actual air quantity, achieving precise control of the actual excess air coefficient and ensuring that the actual excess air coefficient is always within the preset excess air coefficient threshold range. The logic is simple, and the control accuracy and calculation efficiency of the actual excess air coefficient are improved.

[0066] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present invention, nor is it intended to limit the scope of the present invention. Other features of the present invention will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0068] Figure 1 A flow chart of a method for controlling excess air coefficient of a natural gas engine provided by an embodiment of the present invention;

[0069] Figure 2 A flow chart of a second method for controlling excess air coefficient of a natural gas engine provided by an embodiment of the present invention;

[0070] Figure 3 A flow chart of a third method for controlling excess air coefficient of a natural gas engine provided by an embodiment of the present invention;

[0071] Figure 4 A schematic structural diagram of a natural gas engine provided by an embodiment of the present invention;

[0072] Figure 5 A flowchart of a fourth method for controlling excess air coefficient of a natural gas engine provided by an embodiment of the present invention;

[0073] Figure 6 A schematic structural diagram of a control device for excess air coefficient of a natural gas engine provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0074] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0075] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0076] In one embodiment, Figure 1 This is a flow chart of a method for controlling the excess air coefficient of a natural gas engine provided by an embodiment of the present invention. This embodiment is applicable to situations where the actual excess air coefficient needs to be kept within a threshold range when the engine is in a steady-state or transient state. This method can be executed by a control device for the excess air coefficient of a natural gas engine. The control device for the excess air coefficient of a natural gas engine can be implemented in the form of hardware and / or software, and the control device for the excess air coefficient of a natural gas engine can be configured in a vehicle. Figure 1 As shown, the method includes:

[0077] S110 , according to a preset cycle, in the current control cycle, obtaining the current state signal of the engine and the cylinder pressure signal, as well as the actual excess air coefficient of the previous control cycle.

[0078] The preset period is a pre-set signal acquisition cycle with a specific time step. The current engine status signal includes the engine accelerator pedal signal, the engine brake pedal signal, and the engine speed signal. The excess air coefficient is the ratio of the actual amount of air supplied for natural gas combustion to the theoretical minimum amount of air required for complete natural gas combustion, reflecting the natural gas-air balance.

[0079] Specifically, the method of obtaining the current engine state signal and cylinder pressure signal may include but is not limited to setting different sensors for acquisition. Similarly, the method of obtaining the actual excess air coefficient in the previous control cycle may include but is not limited to obtaining it through an oxygen sensor.

[0080] S120 : Determine a target air volume according to an engine accelerator pedal signal, an engine speed signal, and a cylinder pressure signal.

[0081] The target air volume is the target value of the amount of air that needs to be introduced into the cylinder under the current working state of the engine.

[0082] Specifically, after obtaining the engine throttle pedal signal, engine speed signal and cylinder pressure signal, the target air volume under the current operating condition of the engine can be determined through a pre-lookup table or algorithm calculation based on the obtained engine throttle pedal signal, engine speed signal and cylinder pressure signal.

[0083] S130: Determine the operating state of the engine according to the relationship between the current engine state signal and the signal threshold.

[0084] The engine operating state includes steady-state and transient operating conditions. The current engine state signal may include an accelerator pedal signal and a brake pedal signal. A steady-state operating condition indicates that the engine is in a stable operating state during the control cycle. A transient operating condition indicates that the engine is in a transient operating state of acceleration or deceleration during the control cycle.

[0085] Specifically, after obtaining the current engine state signal, the relationship between the current engine state signal and the corresponding signal threshold is determined based on the obtained current engine state signal. When the current engine state signal is less than the corresponding signal threshold, it indicates that the engine is in a relatively stable operating state during the current control cycle, and the engine operating state is currently a steady-state condition. When the current engine state signal is greater than the corresponding signal threshold, it indicates that the engine operating state has experienced significant fluctuations during the current control cycle, possibly in an acceleration or deceleration state, and the engine operating state is currently a transient condition.

[0086] S140: Determine the actual air volume according to the cylinder pressure signal and the operating state of the engine.

[0087] The actual air volume is the actual amount of air that enters the cylinder under the current working state of the engine.

[0088] Specifically, after determining the engine's operating state, an air volume feedforward value and an air volume compensation value can be calculated based on the engine's operating state and the acquired cylinder pressure signal. The calculated air volume feedforward value and air volume compensation value are then added together to obtain the actual air volume. The air volume compensation value includes a steady-state air volume compensation value under steady-state operating conditions and a transient air volume compensation value under transient operating conditions. When the engine is in steady-state operating conditions, the corresponding transient air volume compensation value is zero. When the engine is in transient operating conditions, the corresponding steady-state air volume compensation value is zero.

[0089] S150 , determining a target natural gas injection amount according to the actual air amount, the actual excess air coefficient of the previous control cycle, the target excess air coefficient, the engine speed signal, and the air-fuel ratio.

[0090] The target excess air coefficient is a preset excess air coefficient determined based on the current engine operating conditions. The air-fuel ratio is the ratio of the mass of natural gas to the mass of air required for theoretical complete combustion of the natural gas, also known as the stoichiometric air-fuel ratio of natural gas.

[0091] Specifically, after calculating the actual air volume, the natural gas injection amount needs to be calculated based on the actual air volume. In this embodiment, the difference between the actual excess air coefficient and the target excess air coefficient during the previous control cycle is calculated. This difference, combined with the engine speed signal, is used to determine the natural gas compensation amount. Furthermore, a natural gas feedforward value is calculated based on the calculated actual air volume and the air-fuel ratio. The natural gas injection amount is then calculated based on the natural gas feedforward value and the natural gas compensation amount.

[0092] S160: Determine a target throttle opening according to the target air volume.

[0093] The throttle opening is the opening angle of the engine throttle, which directly affects the amount of air intake of the engine, thereby controlling the operation of the engine. In this embodiment, the target throttle opening can represent the throttle opening required to introduce a target amount of air into the cylinder under the current operating state of the engine.

[0094] Specifically, after the target air volume is calculated, the target throttle opening corresponding to the target air volume needs to be determined based on the target air volume, so as to ensure that the air volume in the cylinder reaches the target air volume by controlling the target throttle opening.

[0095] S170. Based on the target natural gas injection amount, the target natural gas injection amount is adjusted in real time, and the target natural gas injection timing and the target natural gas injection pulse width are determined according to the real-time adjusted target natural gas injection amount and the engine speed signal; and the natural gas combustion is controlled according to the target throttle opening, the target natural gas injection timing and the target natural gas injection pulse width, and the actual excess air coefficient of the current control cycle is obtained in real time, so that the difference between the actual excess air coefficient of the current control cycle obtained in real time and the target excess air coefficient is within a preset excess air coefficient threshold range.

[0096] The target natural gas injection timing is the time at which natural gas injection begins, which determines the time it takes for the natural gas and air mixture to form and the start of the combustion process. The target natural gas injection pulse width is the duration of natural gas injection, which determines the amount of natural gas injected into the cylinder. The preset excess air coefficient threshold range is a pre-calibrated threshold range related to the current operating state of the engine. Exemplarily, the preset excess air coefficient threshold range can be expressed as [a, b]. The target excess air coefficient is the ideal excess air coefficient, and exemplarily, the target excess air coefficient is 1.

[0097] Specifically, after calculating the target natural gas injection amount, the target natural gas injection amount needs to be adjusted in real time to ensure that the actual excess air coefficient is within a preset excess air coefficient threshold range. In this embodiment, a target natural gas injection timing and a target natural gas injection pulse width can be determined based on the real-time adjusted target natural gas injection amount and the engine speed signal. Methods for determining the target natural gas injection timing and target natural gas injection pulse width include, but are not limited to, pre-calibrating the proportional relationship between the engine speed signal and the target natural gas injection timing, and the proportional relationship between the engine speed signal and the target natural gas injection pulse width. Combining these with the real-time adjusted target natural gas injection amount allows the target natural gas injection timing and target natural gas injection pulse width to be determined. Determining the target natural gas injection timing and target natural gas injection pulse width determines the start time and duration of natural gas injection. Therefore, the throttle valve can be controlled to the target throttle opening, and natural gas injection can be initiated starting at the natural gas injection timing. Simultaneously, a target amount of air is introduced into the cylinder to allow the natural gas and air to mix and combust. When natural gas combustion is complete, an excess air coefficient is generated. This excess air coefficient represents the actual excess air coefficient for the current control cycle, which can be obtained in real time via the oxygen sensor. After obtaining the actual excess air coefficient for the current control cycle, it is compared with the target excess air coefficient to determine whether the difference between the two is within the preset excess air coefficient threshold. If the difference is within the preset excess air coefficient threshold, the actual excess air coefficient has stabilized, and no adjustment is made to the actual excess air coefficient for the current control cycle. When the difference is outside the preset excess air coefficient threshold range, it indicates that the deviation between the actual excess air coefficient and the target excess air coefficient at this time is too large, and the actual excess air coefficient of the current control cycle needs to be adjusted, that is, the actual excess air coefficient of the current control cycle is used as the actual excess air coefficient of the previous control cycle to calculate the target natural gas injection amount, and the cycle is repeated until the difference between the calculated actual excess air coefficient and the target excess air coefficient is within the preset excess air coefficient threshold range, thereby achieving precise control of the actual excess air coefficient.

[0098] The technical solution of the embodiment of the present invention is to obtain the current state signal of the engine and the cylinder pressure signal, as well as the actual excess air coefficient of the previous control cycle in accordance with a preset cycle within the current control cycle; determine the target air volume according to the engine throttle pedal signal, the engine speed signal and the cylinder pressure signal; determine the working state of the engine according to the relationship between the current state signal of the engine and the signal threshold, the working state of the engine including steady-state working state and transient working state; determine the actual air volume according to the cylinder pressure signal and the working state of the engine; determine the actual air volume according to the actual air volume, the actual excess air coefficient of the previous control cycle, the target excess air coefficient, the engine speed signal and the cylinder pressure signal; determine the target air volume according to the relationship between the current state signal of the engine and the signal threshold, the working state of the engine including steady-state working state and transient working state; determine the actual air volume according to the cylinder pressure signal and the working state of the engine; determine the target air volume according to the actual air volume, the actual excess air coefficient of the previous control cycle, the target excess air coefficient and the engine speed signal ... target excess air coefficient and the engine speed signal; determine the target air volume according to the actual air volume, the target excess air coefficient and the engine speed signal; determine the target air volume according to the actual air volume, the target excess air coefficient and the engine speed signal; determine the target air and air-fuel ratio to determine the target natural gas injection quantity; determine the target throttle opening based on the target air quantity; adjust the target natural gas injection quantity in real time based on the target natural gas injection quantity, and determine the target natural gas injection timing and target natural gas injection pulse width based on the real-time adjusted target natural gas injection quantity and the engine speed signal; and control natural gas combustion based on the target throttle opening, target natural gas injection timing, and target natural gas injection pulse width, and obtain the actual excess air coefficient of the current control cycle in real time, so that the difference between the actual excess air coefficient of the current control cycle obtained in real time and the target excess air coefficient is within a preset excess air coefficient threshold range. Utilizing the above method, the actual air quantity is accurately calculated based on the operating state of the engine, and the target natural gas injection quantity is precisely determined based on the actual air quantity, achieving precise control of the actual excess air coefficient and ensuring that the actual excess air coefficient is always within the preset excess air coefficient threshold range. The logic is simple, and the control accuracy and calculation efficiency of the actual excess air coefficient are improved.

[0099] Figure 2 This is a flow chart of a second method for controlling excess air coefficient of a natural gas engine provided by an embodiment of the present invention. The cylinder pressure signal includes an intake manifold pressure signal. This embodiment further refines the specific implementation of S120 in the above embodiment, which determines the target air volume based on the engine accelerator pedal signal, the engine speed signal, and the cylinder pressure signal, as follows:

[0100] Obtain intake manifold temperature signal;

[0101] Determining the target torque based on a first correspondence according to the engine accelerator pedal signal; the first correspondence being a preset correspondence between the engine accelerator pedal signal and the target torque;

[0102] determining a target air charge according to the target torque and the engine speed signal based on a second correspondence relationship; the second correspondence relationship being a preset correspondence relationship among the target torque, the engine speed signal, and the target air charge;

[0103] determining an actual air charge according to the air mass under the intake manifold pressure signal and the intake manifold temperature signal and the air mass under a preset standard state;

[0104] determining a target air volume according to the target air volume and the actual air volume based on a first calculation formula;

[0105] The first calculation formula is: ;

[0106] in, is the target air volume, To target air charge, is the actual air charge, and is the charge adjustment coefficient, is the charge-to-flow coefficient.

[0107] For details not yet provided in this embodiment, please refer to the above embodiments and will not be described again here.

[0108] like Figure 2 As shown, the method includes:

[0109] S210 . According to a preset cycle, in the current control cycle, obtain the current state signal of the engine and the cylinder pressure signal, as well as the actual excess air coefficient of the previous control cycle.

[0110] S211: Acquire an intake manifold temperature signal.

[0111] Among them, the intake manifold is a pipeline that evenly circulates air and exhaust in the intake pipe to each cylinder.

[0112] Specifically, the intake manifold temperature signal may be obtained in a manner including but not limited to obtaining it through a temperature sensor.

[0113] S212: Determine a target torque according to the engine accelerator pedal signal and based on the first corresponding relationship.

[0114] The first correspondence is a preset correspondence between the engine accelerator pedal signal and the target torque. In this embodiment, the first correspondence can be a table or a two-dimensional chart, with the engine accelerator pedal signal as input and the target torque as output.

[0115] Specifically, after the engine accelerator pedal signal is acquired, the target torque may be determined according to a calibrated first correspondence between the engine accelerator pedal signal and the target torque.

[0116] S213 : Determine a target air charge according to the target torque and the engine speed signal based on a second corresponding relationship.

[0117] The second correspondence is a preset correspondence between the target torque, the engine speed signal, and the target air charge. In this embodiment, the second correspondence can be a table or a two-dimensional chart, with the target torque and the engine speed signal as input and the target air charge as output. The target air charge is the target amount of air to be filled into the engine cylinder. In this embodiment, a preset correspondence exists between the target air charge, the target torque, and the engine speed.

[0118] Specifically, after the target torque is determined, the corresponding target air charge can be determined based on the calculated target torque and the engine speed signal in combination with the calibrated second corresponding relationship.

[0119] S214 : Determine an actual air charge according to the air mass under the intake manifold pressure signal and the intake manifold temperature signal and the air mass under a preset standard state.

[0120] The actual air charge is the ratio of the air mass at the current intake manifold air pressure and intake manifold temperature to the air mass at a preset standard state. For example, the preset standard state is atmospheric pressure at a pressure of 1013 hPa and a temperature of 273 K.

[0121] Specifically, after determining the target air charge, the actual air charge needs to be determined based on the target air charge. In this embodiment, the air mass at the intake manifold pressure signal and intake manifold temperature signal can be determined based on the obtained intake manifold pressure signal and intake manifold temperature signal. This determination can be performed, for example, through table lookup or algorithmic calculation. Simultaneously, the air mass at a preset standard state is obtained, and the air mass at the intake manifold pressure signal and intake manifold temperature signal is divided by the air mass at the preset standard state to obtain a ratio between the two. This ratio is the timed air charge.

[0122] S215 : Determine a target air volume according to the target air volume and the actual air volume based on a first calculation formula.

[0123] The first calculation formula is: ;

[0124] in, is the target air volume, To target air charge, is the actual air charge, and is the charge adjustment coefficient, is the charge-to-flow coefficient.

[0125] Specifically, after determining the actual air charge and the target air charge, combined with the first calculation formula, the charge adjustment coefficient and And the charge conversion coefficient It can be determined by pre-setting the calibration. After the determination is made, the determined 、 、 , actual air charge and target air charge are substituted into the first calculation formula to determine the target air charge. .

[0126] S216: Determine the operating state of the engine according to the relationship between the current engine state signal and the signal threshold.

[0127] S217: Determine the actual air volume according to the cylinder pressure signal and the operating state of the engine.

[0128] S218: Determine a target natural gas injection amount based on the actual air amount, the actual excess air coefficient of the previous control cycle, the target excess air coefficient, the engine speed signal, and the air-fuel ratio.

[0129] S219: Determine a target throttle opening according to the target air volume.

[0130] S220. Based on the target natural gas injection amount, adjust the target natural gas injection amount in real time, and determine the target natural gas injection timing and the target natural gas injection pulse width according to the real-time adjusted target natural gas injection amount and the engine speed signal; and control the natural gas combustion according to the target throttle opening, the target natural gas injection timing and the target natural gas injection pulse width, and obtain the actual excess air coefficient of the current control cycle in real time, so that the difference between the actual excess air coefficient of the current control cycle obtained in real time and the target excess air coefficient is within a preset excess air coefficient threshold range.

[0131] The technical solution of the embodiment of the present invention is to obtain the temperature signal of the intake manifold; determine the target torque based on the first correspondence according to the engine throttle pedal signal; the first correspondence is a preset correspondence between the engine throttle pedal signal and the target torque; determine the target air charge based on the second correspondence according to the target torque and the engine speed signal; the second correspondence is a preset correspondence between the target torque, the engine speed signal and the target air charge; determine the actual air charge according to the intake manifold pressure signal, the air quality under the temperature signal and the air quality under the preset standard state; determine the target air volume based on the first calculation formula according to the target air volume and the actual air volume. Using the above method, the size of the target air volume is accurately determined, providing a basis for subsequently determining the target throttle opening according to the target air volume.

[0132] Figure 3 This is a flow chart of a third method for controlling excess air coefficient of a natural gas engine provided by an embodiment of the present invention. Figure 4 This is a structural diagram of a natural gas engine provided by an embodiment of the present invention. This embodiment refines the specific implementation method of the above-mentioned embodiment S130, which determines the working state of the engine based on the relationship between the current state signal of the engine and the signal threshold, as follows:

[0133] When the engine accelerator pedal signal is greater than the accelerator pedal signal threshold, or the engine brake pedal signal is greater than the brake pedal signal threshold, determining that the engine is in a transient operating state;

[0134] When the engine accelerator pedal signal is less than the accelerator pedal signal threshold, or the engine brake pedal signal is less than the brake pedal signal threshold, it is determined that the engine is in a steady-state operating condition.

[0135] Furthermore, the specific implementation of S140 in the above embodiment for determining the actual air volume based on the cylinder pressure signal and the engine operating state is refined as follows:

[0136] Determine the air volume feedforward value based on the cylinder pressure signal; the cylinder pressure signal includes the intake manifold pressure signal, the gas partial pressure signal flowing through the EGR valve, the natural gas partial pressure signal, and the residual gas partial pressure signal;

[0137] When the engine is in a steady-state operating condition, a steady-state air volume compensation value is determined according to the engine speed signal and the intake manifold pressure signal;

[0138] When the engine is in transient working condition, the transient air volume compensation value is determined based on multiple cylinder pressure signals;

[0139] The actual air volume is determined based on the engine's operating state, the air volume feedforward value, the steady-state air volume compensation value, and the transient air volume compensation value.

[0140] For details not yet provided in this embodiment, please refer to the above embodiments and will not be described again here.

[0141] like Figure 3 and Figure 4 As shown, the method includes:

[0142] S310 , according to a preset cycle, in the current control cycle, obtain the current state signal of the engine and the cylinder pressure signal, as well as the actual excess air coefficient of the previous control cycle.

[0143] S311 : Determine a target air volume according to an engine accelerator pedal signal, an engine speed signal, and a cylinder pressure signal.

[0144] S312: When the engine accelerator pedal signal is greater than the accelerator pedal signal threshold, or the engine brake pedal signal is greater than the brake pedal signal threshold, determine that the engine is in a transient operating condition.

[0145] S313: When the engine accelerator pedal signal is less than the accelerator pedal signal threshold, or the engine brake pedal signal is less than the brake pedal signal threshold, determine that the engine is in a steady-state operating condition.

[0146] Specifically, after obtaining the engine accelerator pedal signal or the engine brake pedal signal, it is necessary to determine whether the engine accelerator pedal signal is within the accelerator pedal signal threshold, or whether the engine brake pedal signal is within the brake pedal signal threshold. If it is determined that the engine accelerator pedal signal is greater than the accelerator pedal signal threshold, or the engine brake pedal signal is greater than the brake pedal signal threshold, it indicates that the engine has experienced significant fluctuations in the current control cycle, and the vehicle may be in the acceleration or deceleration stage. At this time, the engine operating state is a transient operating state. If it is determined that the engine accelerator pedal signal is less than the accelerator pedal signal threshold, or the engine brake pedal signal is less than the brake pedal signal threshold, it indicates that the engine is in a relatively stable operating state in the current control cycle, and the engine operating state is a steady-state operating state.

[0147] S314: Determine an air volume feedforward value according to the cylinder pressure signal.

[0148] This step can be further refined as follows: according to the cylinder pressure signal, the air volume feedforward value is determined based on the second calculation formula. The second calculation formula is: ;in, is the air volume feedforward value, is the intake manifold pressure signal, is the gas partial pressure signal flowing through the EGR valve, is the natural gas partial pressure signal, is the residual gas partial pressure signal.

[0149] The cylinder pressure signal includes the intake manifold pressure signal, the partial pressure signal of the gas flowing through the EGR valve, the natural gas partial pressure signal, and the residual gas partial pressure signal. The air mass feedforward value represents a pure air mass feedforward value calculated in advance and input into the system to respond to certain expected changes or disturbances.

[0150] Specifically, refer to Figure 4 After obtaining the cylinder pressure signal, that is, the intake manifold pressure signal , Gas partial pressure signal flowing through the EGR valve , natural gas partial pressure signal and residual gas partial pressure signal (not shown in the figure), intake manifold pressure signal The total air pressure entering the cylinder includes the gas partial pressure signal flowing through the EGR valve. , natural gas partial pressure signal , residual gas partial pressure signal As well as the pure air partial pressure, the intake manifold pressure signal is required to calculate the air volume feedforward value corresponding to the pure air partial pressure. The gas partial pressure signal flowing through the EGR valve , natural gas partial pressure signal and residual gas partial pressure signal The sum of is subtracted. It is the air volume feedforward value.

[0151] S315: When the engine is in a steady-state operating condition, determine a steady-state air volume compensation value according to the engine speed signal and the intake manifold pressure signal.

[0152] Among them, this step can be refined as follows: when the engine is in a steady-state operating condition, determining the predicted time according to the intake manifold pressure signal; determining the air partial pressure of the intake manifold based on the intake manifold pressure signal, the gas partial pressure signal flowing through the EGR valve, and the natural gas partial pressure signal based on a third calculation formula; determining the steady-state air volume compensation value based on the predicted time, the air partial pressure of the intake manifold, and the engine speed signal based on a fourth calculation formula; the third calculation formula is: ; The fourth calculation formula is: ;in, is the steady-state air volume compensation value, is the intake manifold pressure signal, is the gas partial pressure signal flowing through the EGR valve, is the natural gas partial pressure signal, is the air partial pressure signal of the intake manifold, is the engine speed signal, It is the preset correspondence between the air partial pressure of the intake manifold and the engine speed signal. Forecast time.

[0153] The steady-state air volume compensation value is a steady-state compensation for the air volume feedforward value.

[0154] Specifically, when determining that the engine is in steady-state operating condition, refer to Figure 4 , The time point in a control cycle when the actual amount of air entering the cylinder is calculated. The actual amount of air entering the cylinder within a control cycle is the time point at which the intake is completed. There is a time difference between the two. is the preset calculation time point, but in fact At this moment, the piston has not reached the bottom dead center position, and the actual amount of air has not yet entered. Therefore, it is necessary to consider the time point when the actual amount of air intake is completed. , thus improving the calculation accuracy of the air volume compensation value. In this embodiment, the prediction time is set , indicating the actual air volume entering the completion time point Calculation time point with actual air volume entering Therefore, in determining the prediction time When Moment and Determine at any time, usually, Moment and There is a certain corresponding relationship between the time and the intake manifold pressure, so the intake manifold pressure signal can be used to calculate the Sure Moment and time, and Once confirmed, the predicted time is also determined It should be noted that when the engine is in steady state, the predicted time The control period is within the normal fluctuation range, so subsequent calculations can be performed based on the cylinder pressure signal obtained once. In other words, the predicted time is determined. Afterwards, the air partial pressure of the intake manifold needs to be determined. In this embodiment, the third calculation formula can be used: , the intake manifold pressure signal is known , Gas partial pressure signal flowing through the EGR valve and natural gas partial pressure signal , the air partial pressure of the intake manifold can be determined according to the third calculation formula . Determine the air partial pressure in the intake manifold and prediction time Then, combined with the engine speed signal , using the air partial pressure of the manifold and engine speed signal The preset correspondence between the two, combined with the prediction time ,Right now , the steady-state air volume compensation value can be determined .

[0155] S316: When the engine is in a transient operating state, determine a transient air volume compensation value based on multiple cylinder pressure signals.

[0156] Among them, this step can be refined as follows: when the engine is in a transient operating condition, the air partial pressures of the N intake manifolds are determined based on the third calculation formula according to the N intake manifold pressure signals, the gas partial pressure signal flowing through the EGR valve, and the natural gas partial pressure signal; based on the N intake manifold air partial pressures, the transient air volume compensation value is determined based on the fifth calculation formula; the fifth calculation formula is: ;in, is the transient air volume compensation value, 、 、 、 and is the air partial pressure of N intake manifolds, is the number of collections, To predict the time, The preset collection period.

[0157] in, is the transient air volume compensation value, 、 、 、 and is the air partial pressure of N intake manifolds, is the number of collections, To predict the time, The preset collection period.

[0158] The transient air volume compensation value is a transient compensation for the air volume feedforward value.

[0159] Specifically, when the engine is in transient operating conditions, the predicted time The intake manifold pressure signal exceeds the normal fluctuation range in the current control cycle. , Gas partial pressure signal flowing through the EGR valve and natural gas partial pressure signal Therefore, when calculating the transient air volume compensation value, it is necessary to start the intake manifold pressure signal. , Gas partial pressure signal flowing through the EGR valve and natural gas partial pressure signal Multiple acquisition function, that is, acquiring N intake manifold pressure signals within the control cycle , Gas partial pressure signal flowing through the EGR valve and natural gas partial pressure signal The collected data and the intake manifold pressure signal at the same time The gas partial pressure signal flowing through the EGR valve at the same time and natural gas partial pressure signal Subtract and get the air partial pressure of N intake manifolds , using the air partial pressure of N intake manifolds In this preset collection cycle The change in the air volume is used to calculate the transient air volume compensation value. In this embodiment, the fifth calculation formula is used, namely , the preset collection period is known and prediction time , after substituting into the fifth calculation formula, the transient air volume compensation value can be determined .

[0160] S317: Determine the actual air volume according to the engine operating state, the air volume feedforward value, the steady-state air volume compensation value, and the transient air volume compensation value.

[0161] Among them, this step can be further refined as follows: when the engine is in a steady-state operating condition, the actual air volume is determined based on the air volume feedforward value and the steady-state air volume compensation value; or, when the engine is in a transient operating condition, the actual air volume is determined based on the air volume feedforward value and the transient air volume compensation value.

[0162] Specifically, when the engine is in a steady-state operating condition, the actual air volume can be determined by adding the determined air volume feedforward value and the steady-state air volume compensation value, that is, ,in, is the actual air volume, is the air volume feedforward value, is the steady-state air volume compensation value. When the engine is in transient working condition, the actual air volume can be determined by adding the determined air volume feedforward value and the transient air volume compensation value, that is, ,in, It is the instantaneous air volume compensation value.

[0163] S318: Determine a target natural gas injection amount based on the actual air amount, the actual excess air coefficient of the previous control cycle, the target excess air coefficient, the engine speed signal, and the air-fuel ratio.

[0164] S319: Determine a target throttle opening according to the target air volume.

[0165] S320. Based on the target natural gas injection amount, adjust the target natural gas injection amount in real time, and determine the target natural gas injection timing and the target natural gas injection pulse width according to the real-time adjusted target natural gas injection amount and the engine speed signal; and control the natural gas combustion according to the target throttle opening, the target natural gas injection timing and the target natural gas injection pulse width, and obtain the actual excess air coefficient of the current control cycle in real time, so that the difference between the actual excess air coefficient of the current control cycle obtained in real time and the target excess air coefficient is within a preset excess air coefficient threshold range.

[0166] The technical solution of the embodiment of the present invention determines that the engine is in a transient operating state when the engine throttle pedal signal is greater than the throttle pedal signal threshold, or when the engine brake pedal signal is greater than the brake pedal signal threshold; determines that the engine is in a steady-state operating state when the engine throttle pedal signal is less than the throttle pedal signal threshold, or when the engine brake pedal signal is less than the brake pedal signal threshold; determines an air volume feedforward value based on the cylinder pressure signal; determines a steady-state air volume compensation value based on the engine speed signal and the intake manifold pressure signal when the engine is in a steady-state operating state; determines a transient air volume compensation value based on multiple cylinder pressure signals when the engine is in a transient operating state; and determines the actual air volume based on the engine's operating state, the air volume feedforward value, the steady-state air volume compensation value, and the transient air volume compensation value. Utilizing the above method, the engine's operating state is determined, and the actual air volume is accurately determined according to different engine operating states, thereby improving the accuracy and efficiency of the actual air volume calculation.

[0167] Figure 5 This is a flow chart of a fourth method for controlling the excess air coefficient of a natural gas engine provided by an embodiment of the present invention. This embodiment refines the specific implementation method of determining the target natural gas injection amount based on the actual air amount, the actual excess air coefficient of the previous control cycle, the target excess air coefficient, the engine speed signal, and the air-fuel ratio in S150 of the above embodiment as follows:

[0168] Determine the target natural gas feedforward value based on the sixth calculation formula according to the actual air quantity and air-fuel ratio;

[0169] determining a target natural gas compensation amount based on a seventh calculation formula according to a difference between an actual excess air coefficient and a target excess air coefficient in a previous control cycle and an engine speed signal;

[0170] determining a target natural gas injection amount according to a target natural gas feedforward value and a target natural gas compensation amount;

[0171] The sixth calculation formula is: , the seventh calculation formula is: ;

[0172] in, is the target natural gas feedforward value, is the actual air volume, is the air-fuel ratio, is the target natural gas compensation amount, is the difference between the actual excess air coefficient and the target excess air coefficient in the previous control cycle, is the engine speed signal, It is a preset correspondence between the engine speed signal and the difference.

[0173] Furthermore, the specific implementation method of determining the target throttle opening according to the target air volume in S160 in the above embodiment is refined as follows:

[0174] Get the current ambient temperature, current ambient pressure, throttle inlet pressure and throttle outlet pressure;

[0175] According to the target air volume, the current ambient temperature, and the current ambient pressure, the target air volume is normalized based on an eighth calculation formula to determine a normalized target air volume;

[0176] determining a target throttle opening based on a third correspondence according to the standardized target air volume, the engine speed signal, the throttle inlet pressure, and the throttle outlet pressure;

[0177] The eighth calculation formula is: , the third corresponding relationship is: ;

[0178] in, is the standardized target air volume, is the target air volume, is the current ambient temperature, Due to the current environmental pressure, is the correction factor, is the target throttle opening, is the throttle outlet pressure, is the throttle inlet pressure, is the engine speed signal, It is a preset correspondence between the target throttle opening, the ratio of the throttle outlet pressure to the throttle inlet pressure and the engine speed signal.

[0179] For details not yet provided in this embodiment, please refer to the above embodiments and will not be described again here.

[0180] like Figure 5 As shown, the method includes:

[0181] S410: According to a preset cycle, in the current control cycle, obtain the current state signal of the engine and the cylinder pressure signal, as well as the actual excess air coefficient of the previous control cycle.

[0182] S411 : Determine a target air volume according to an engine accelerator pedal signal, an engine speed signal, and a cylinder pressure signal.

[0183] S412: Determine the operating state of the engine according to the relationship between the current state signal of the engine and the signal threshold.

[0184] S413: Determine the actual air volume according to the cylinder pressure signal and the operating state of the engine.

[0185] S414: Determine a target natural gas feedforward value according to the actual air quantity and air-fuel ratio based on a sixth calculation formula.

[0186] The sixth calculation formula is: ,in, is the target natural gas feedforward value, is the actual air volume, is the air-fuel ratio.

[0187] Specifically, after determining the actual air volume, according to the air-fuel ratio, use the sixth calculation formula , the actual air volume known and air-fuel ratio After substituting, the target natural gas feedforward value can be calculated .

[0188] S415: Determine a target natural gas compensation amount based on a seventh calculation formula according to a difference between the actual excess air coefficient and the target excess air coefficient in the previous control cycle and the engine speed signal.

[0189] The seventh calculation formula is: ;in, is the target natural gas compensation amount, is the difference between the actual excess air coefficient and the target excess air coefficient in the previous control cycle, is the engine speed signal, It is a preset correspondence between the engine speed signal and the difference.

[0190] Specifically, after obtaining the actual excess air coefficient of the previous control cycle, the difference between the actual excess air coefficient of the previous control cycle and the target excess air coefficient is calculated, that is, , is the target excess air coefficient, is the actual excess air coefficient, The difference is the difference, and the difference in excess air coefficient can be calculated. Combined with the engine speed signal, according to the preset correspondence between the difference and the engine speed signal, that is, , the target natural gas compensation amount can be determined. For example, The specific corresponding relationship can be determined through multiple experiments, simulations, or algorithm verification, and is not specifically limited here.

[0191] S416: Determine a target natural gas injection amount according to the target natural gas feedforward value and the target natural gas compensation amount.

[0192] Specifically, after determining the target natural gas feedforward value and the target natural gas compensation amount, the target natural gas feedforward value and the target natural gas compensation amount are added together, that is, , is the target natural gas feedforward value, is the target natural gas compensation amount, is the target natural gas injection amount.

[0193] S417: Obtain the current ambient temperature, current ambient pressure, throttle inlet pressure, and throttle outlet pressure.

[0194] Specifically, the method of obtaining the current ambient temperature, current ambient pressure, throttle inlet pressure and throttle outlet pressure may include but is not limited to using corresponding thermometers, pressure gauges or devices that display ambient temperature and pressure on electronic instruments, etc. The specific method can be determined according to actual conditions and is not limited here.

[0195] S418 : According to the target air volume, the current ambient temperature, and the current ambient pressure, the target air volume is standardized based on the eighth calculation formula to determine the standardized target air volume.

[0196] Specifically, according to the current ambient temperature and the current ambient pressure, a correction coefficient under the current ambient temperature and the current ambient pressure can be determined, and the determined correction coefficient is multiplied by the target air volume, that is, the eighth calculation formula is used: ,in, is the standardized target air volume, is the target air volume, is the current ambient temperature, Due to the current environmental pressure, is the correction factor, and the correction factor and target air volume After substituting, the standardized target air volume can be determined , thereby eliminating the influence of the current ambient temperature and the current ambient pressure on the target air volume.

[0197] S419: Determine a target throttle opening according to the standardized target air volume, the engine speed signal, the throttle inlet pressure, and the throttle outlet pressure based on a third corresponding relationship.

[0198] The third corresponding relationship is: ;in, is the target throttle opening, is the throttle outlet pressure, is the throttle inlet pressure, is the engine speed signal, It is a preset correspondence between the target throttle opening, the ratio of the throttle outlet pressure to the throttle inlet pressure and the engine speed signal.

[0199] Specifically, determine the standardized target air volume Afterwards, according to the standardized target air volume , combined with the obtained throttle inlet pressure, throttle outlet pressure and engine speed signal, the target throttle opening can be determined according to the third corresponding relationship .in, The determination method may include but is not limited to determining the specific corresponding relationship through multiple experiments, simulations or algorithm verification, and is not specifically limited here.

[0200] S420. Based on the target natural gas injection amount, the target natural gas injection amount is adjusted in real time, and the target natural gas injection timing and the target natural gas injection pulse width are determined according to the real-time adjusted target natural gas injection amount and the engine speed signal; and the natural gas combustion is controlled according to the target throttle opening, the target natural gas injection timing and the target natural gas injection pulse width, and the actual excess air coefficient of the current control cycle is obtained in real time, so that the difference between the actual excess air coefficient of the current control cycle obtained in real time and the target excess air coefficient is within a preset excess air coefficient threshold range.

[0201] The technical solution of the embodiment of the present invention determines a target natural gas feedforward value based on the sixth calculation formula according to the actual air quantity and air-fuel ratio; determines a target natural gas compensation amount based on the seventh calculation formula according to the difference between the actual excess air coefficient and the target excess air coefficient in the previous control cycle and the engine speed signal; determines a target natural gas injection amount based on the target natural gas feedforward value and the target natural gas compensation amount; obtains the current ambient temperature, current ambient pressure, throttle inlet pressure, and throttle outlet pressure; normalizes the target air quantity based on the target air quantity, current ambient temperature, and current ambient pressure according to the eighth calculation formula to determine a standardized target air quantity; and determines a target throttle opening based on the standardized target air quantity, the engine speed signal, and the throttle inlet pressure and throttle outlet pressure based on a third corresponding relationship. Using this method, the target natural gas injection amount and the target throttle opening are accurately determined based on the actual air quantity, thereby improving calculation accuracy and efficiency and providing a basis for subsequently determining the actual excess air coefficient of the current cycle based on the natural gas injection amount and throttle opening.

[0202] Figure 6 A schematic diagram of a control device for excess air coefficient of a natural gas engine provided by an embodiment of the present invention, referring to Figure 6 As shown, the control device includes:

[0203] The signal acquisition module 110 is configured to acquire, within a preset period, an engine current state signal and a cylinder pressure signal within a current control cycle, as well as an actual excess air coefficient from a previous control cycle; the engine current state signal includes an engine accelerator pedal signal, an engine brake pedal signal, and an engine speed signal;

[0204] a target air volume determination module 120 for determining a target air volume based on an engine accelerator pedal signal, an engine speed signal, and a cylinder pressure signal;

[0205] The working state determination module 130 is used to determine the working state of the engine according to the relationship between the current state signal of the engine and the signal threshold. The working state of the engine includes a steady state working state and a transient working state.

[0206] The actual air volume determination module 140 is used to determine the actual air volume according to the cylinder pressure signal and the operating state of the engine;

[0207] a target natural gas injection amount determination module 150 for determining a target natural gas injection amount based on the actual air amount, the actual excess air coefficient of the previous control cycle, the target excess air coefficient, the engine speed signal, and the air-fuel ratio;

[0208] A target throttle opening determination module 160 is configured to determine a target throttle opening according to a target air volume;

[0209] The real-time control module 170 is used to adjust the target natural gas injection amount in real time based on the target natural gas injection amount, and determine the target natural gas injection timing and target natural gas injection pulse width based on the real-time adjusted target natural gas injection amount and the engine speed signal; and control the natural gas combustion based on the target throttle opening, the target natural gas injection timing and the target natural gas injection pulse width, and obtain the actual excess air coefficient of the current control cycle in real time, so that the difference between the actual excess air coefficient of the current control cycle obtained in real time and the target excess air coefficient is within a preset excess air coefficient threshold range.

[0210] The control device for the excess air coefficient of a natural gas engine provided in an embodiment of the present invention can execute the control method for the excess air coefficient of a natural gas engine provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method.

[0211] Optionally, the target air volume determination module 120 is further configured to: obtain an intake manifold temperature signal; determine a target torque based on a first correspondence according to an engine accelerator pedal signal; the first correspondence being a preset correspondence between the engine accelerator pedal signal and the target torque; determine a target air charge based on a second correspondence according to the target torque and the engine speed signal; the second correspondence being a preset correspondence between the target torque, the engine speed signal, and the target air charge; determine an actual air charge based on the air mass under the intake manifold pressure signal and the intake manifold temperature signal and the air mass under a preset standard state; determine a target air volume based on a first calculation formula according to the target air charge and the actual air charge; the first calculation formula being: ;in, is the target air volume, To target air charge, is the actual air charge, and is the charge adjustment coefficient, is the charge-to-flow coefficient.

[0212] Optionally, the working state determination module 130 is further configured to: determine that the engine is in a transient operating condition when the engine throttle pedal signal is greater than the throttle pedal signal threshold, or the engine brake pedal signal is greater than the brake pedal signal threshold; determine that the engine is in a steady-state operating condition when the engine throttle pedal signal is less than the throttle pedal signal threshold, or the engine brake pedal signal is less than the brake pedal signal threshold.

[0213] Optionally, the actual air volume determination module 140 is further configured to: determine an air volume feedforward value based on a cylinder pressure signal; the cylinder pressure signal also includes a gas partial pressure signal, a natural gas partial pressure signal and a residual gas partial pressure signal flowing through the EGR valve; when the engine is in a steady-state operating condition, determine a steady-state air volume compensation value based on an engine speed signal and an intake manifold pressure signal; when the engine is in a transient operating condition, determine a transient air volume compensation value based on multiple cylinder pressure signals; determine the actual air volume based on the engine's operating state, the air volume feedforward value, the steady-state air volume compensation value and the transient air volume compensation value.

[0214] Optionally, the actual air volume determination module 140 is further configured to: determine the air volume feedforward value according to the cylinder pressure signal, including: determining the air volume feedforward value according to the cylinder pressure signal based on a second calculation formula;

[0215] Optionally, the actual air volume determination module 140 is further configured to: determine a predicted time according to the intake manifold pressure signal when the engine is in a steady-state operating condition; determine the air partial pressure of the intake manifold based on a third calculation formula according to the intake manifold pressure signal, the gas partial pressure signal flowing through the EGR valve, and the natural gas partial pressure signal; determine a steady-state air volume compensation value based on a fourth calculation formula according to the predicted time, the air partial pressure of the intake manifold, and the engine speed signal; determine the air partial pressures of N intake manifolds based on the third calculation formula when the engine is in a transient operating condition according to N intake manifold pressure signals, the gas partial pressure signal flowing through the EGR valve, and the natural gas partial pressure signal; and determine a transient air volume compensation value based on the fifth calculation formula according to the air partial pressures of the N intake manifolds; the third calculation formula is: ; The fourth calculation formula is: ; The fifth calculation formula is: ;in, is the steady-state air volume compensation value, is the intake manifold pressure signal, is the gas partial pressure signal flowing through the EGR valve, is the natural gas partial pressure signal, is the air partial pressure signal of the intake manifold, is the engine speed signal, It is the preset correspondence between the air partial pressure of the intake manifold and the engine speed signal. For the prediction time; is the transient air volume compensation value, 、 、 、 and is the air partial pressure of N intake manifolds, is the number of collections, The preset collection period.

[0216] Optionally, the actual air volume determination module 140 is further configured to: determine the actual air volume based on the air volume feedforward value and the steady-state air volume compensation value when the engine is in a steady-state operating condition; or determine the actual air volume based on the air volume feedforward value and the transient air volume compensation value when the engine is in a transient operating condition.

[0217] Optionally, the target natural gas injection amount determination module 150 is further configured to: determine a target natural gas feedforward value based on the actual air amount and the air-fuel ratio based on a sixth calculation formula; determine a target natural gas compensation amount based on a difference between the actual excess air coefficient and the target excess air coefficient in the previous control cycle and the engine speed signal based on a seventh calculation formula; and determine a target natural gas injection amount based on the target natural gas feedforward value and the target natural gas compensation amount. The sixth calculation formula is: , the seventh calculation formula is: ;in, is the target natural gas feedforward value, is the actual air volume, is the air-fuel ratio, is the target natural gas compensation amount, is the difference between the actual excess air coefficient and the target excess air coefficient in the previous control cycle, is the engine speed signal, It is a preset correspondence between the engine speed signal and the difference.

[0218] Optionally, the target throttle opening determination module 160 is further configured to: obtain the current ambient temperature, the current ambient pressure, the throttle inlet pressure, and the throttle outlet pressure; normalize the target air volume according to the target air volume, the current ambient temperature, and the current ambient pressure based on an eighth calculation formula to determine the standardized target air volume; and determine the target throttle opening according to the standardized target air volume, the engine speed signal, the throttle inlet pressure, and the throttle outlet pressure based on a third corresponding relationship; the eighth calculation formula is: , the third corresponding relationship is: ;in, is the standardized target air volume, is the target air volume, is the current ambient temperature, Due to the current environmental pressure, is the correction factor, is the target throttle opening, is the throttle outlet pressure, is the throttle inlet pressure, is the engine speed signal, It is a preset correspondence between the target throttle opening, the ratio of the throttle outlet pressure to the throttle inlet pressure and the engine speed signal.

[0219] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in the present invention can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of the present invention can be achieved. This is not limited herein.

[0220] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A method for controlling excess air coefficient of a natural gas engine, characterized in that: include: According to a preset cycle, within the current control cycle, the current state signal of the engine and the cylinder pressure signal, as well as the actual excess air coefficient of the previous control cycle are obtained; The engine current state signal includes an engine accelerator pedal signal, an engine brake pedal signal and an engine speed signal; determining a target air volume according to the engine accelerator pedal signal, the engine speed signal, and the cylinder pressure signal; determining the operating state of the engine according to a relationship between the current engine state signal and a signal threshold, wherein the operating state of the engine includes a steady-state operating state and a transient operating state; determining an actual air volume according to the cylinder pressure signal and the operating state of the engine; determining a target natural gas injection amount according to the actual air amount, the actual excess air coefficient of the previous control cycle, the target excess air coefficient, the engine speed signal, and the air-fuel ratio; determining a target throttle opening according to the target air volume; Based on the target natural gas injection amount, the target natural gas injection amount is adjusted in real time, and a target natural gas injection timing and a target natural gas injection pulse width are determined based on the real-time adjusted target natural gas injection amount and the engine speed signal; and natural gas combustion is controlled based on the target throttle opening, the target natural gas injection timing, and the target natural gas injection pulse width, and an actual excess air coefficient of a current control cycle is obtained in real time, so that a difference between the real-time obtained actual excess air coefficient of the current control cycle and the target excess air coefficient is within a preset excess air coefficient threshold range. The cylinder pressure signal includes an intake manifold pressure signal; determining a target air volume according to the engine accelerator pedal signal, the engine speed signal, and the cylinder pressure signal, including: Obtain intake manifold temperature signal; determining a target torque according to the engine accelerator pedal signal and based on a first correspondence relationship; the first correspondence relationship being a preset correspondence relationship between the engine accelerator pedal signal and the target torque; determining a target air charge according to the target torque and the engine speed signal based on a second correspondence relationship; the second correspondence relationship being a preset correspondence relationship among the target torque, the engine speed signal, and the target air charge; determining an actual air charge according to the air mass under the intake manifold pressure signal and the intake manifold temperature signal and the air mass under a preset standard state; determining a target air volume according to the target air volume and the actual air volume based on a first calculation formula; The first calculation formula is: ; in, is the target air volume, for the target air charge, is the actual air charge, and is the charge adjustment coefficient, is the charge-to-flow coefficient.

2. The control method according to claim 1, characterized in that: Determining the operating state of the engine according to the relationship between the current state signal of the engine and the signal threshold includes: When the engine accelerator pedal signal is greater than an accelerator pedal signal threshold, or the engine brake pedal signal is greater than a brake pedal signal threshold, determining that the engine is in a transient operating state; When the engine accelerator pedal signal is less than an accelerator pedal signal threshold, or the engine brake pedal signal is less than a brake pedal signal threshold, it is determined that the engine is in a steady-state operating condition.

3. The control method according to claim 2, characterized in that: Determining an actual air volume according to the cylinder pressure signal and the operating state of the engine includes: Determining an air quantity feedforward value based on the cylinder pressure signal; the cylinder pressure signal includes an intake manifold pressure signal, a gas partial pressure signal flowing through an EGR valve, a natural gas partial pressure signal, and a residual gas partial pressure signal; When the engine is in the steady-state operating condition, determining a steady-state air volume compensation value according to the engine speed signal and the intake manifold pressure signal; When the engine is in the transient operating condition, determining a transient air volume compensation value according to a plurality of cylinder pressure signals; The actual air amount is determined according to the operating state of the engine, the air amount feedforward value, the steady-state air amount compensation value, and the transient air amount compensation value.

4. The control method according to claim 3, characterized in that: Determining an air volume feedforward value according to the cylinder pressure signal includes: determining an air volume feedforward value based on the cylinder pressure signal and a second calculation formula; The second calculation formula is: ; in, is the air volume feedforward value, is the intake manifold pressure signal, is the gas partial pressure signal flowing through the EGR valve, is the natural gas partial pressure signal, is the residual gas partial pressure signal.

5. The control method according to claim 3, characterized in that: Determining the actual air volume according to the operating state of the engine, the air volume feedforward value, the steady-state air volume compensation value, and the transient air volume compensation value includes: When the engine is in the steady-state operating condition, determining the actual air volume according to the air volume feedforward value and the steady-state air volume compensation value; or When the engine is in the transient operating condition, the actual air volume is determined according to the air volume feedforward value and the transient air volume compensation value.

6. The control method according to claim 1, characterized in that: Determining a target natural gas injection amount according to the actual air amount, the actual excess air coefficient of the previous control cycle, the target excess air coefficient, the engine speed signal, and the air-fuel ratio includes: determining a target natural gas feedforward value according to the actual air amount and the air-fuel ratio based on a sixth calculation formula; determining a target natural gas compensation amount based on a seventh calculation formula according to a difference between the actual excess air coefficient and the target excess air coefficient in a previous control cycle and the engine speed signal; determining the target natural gas injection amount according to the target natural gas feedforward value and the target natural gas compensation amount; The sixth calculation formula is: , the seventh calculation formula is: ; in, is the target natural gas feedforward value, is the actual air volume, is the air-fuel ratio, is the target natural gas compensation amount, is the difference between the actual excess air coefficient and the target excess air coefficient in the previous control cycle, is the engine speed signal, It is a preset corresponding relationship between the engine speed signal and the difference.

7. The control method according to claim 1, characterized in that: Determining a target throttle opening according to the target air volume includes: Get the current ambient temperature, current ambient pressure, throttle inlet pressure and throttle outlet pressure; According to the target air volume, the current ambient temperature, and the current ambient pressure, the target air volume is normalized based on an eighth calculation formula to determine a normalized target air volume; determining the target throttle opening according to the standardized target air volume, the engine speed signal, the throttle inlet pressure, and the throttle outlet pressure based on a third correspondence; The eighth calculation formula is: , the third corresponding relationship is: ; in, is the standardized target air volume, is the target air volume, is the current ambient temperature, is the current environmental pressure, is the correction factor, is the target throttle opening, is the throttle outlet pressure, is the throttle inlet pressure, is the engine speed signal, It is a preset correspondence relationship among the target throttle opening, the ratio of the throttle outlet pressure to the throttle inlet pressure, and the engine speed signal.

8. A control device for excess air coefficient of a natural gas engine, characterized in that: include: a signal acquisition module, configured to acquire, within a preset period, an engine current state signal and a cylinder pressure signal within a current control cycle, as well as an actual excess air coefficient of a previous control cycle; the engine current state signal includes an engine accelerator pedal signal, an engine brake pedal signal, and an engine speed signal; a target air volume determination module, configured to determine a target air volume according to the engine accelerator pedal signal, the engine speed signal, and the cylinder pressure signal; an operating state determining module, configured to determine the operating state of the engine according to a relationship between the current engine state signal and a signal threshold, wherein the operating state of the engine includes a steady state operating state and a transient operating state; an actual air volume determination module, configured to determine the actual air volume according to the cylinder pressure signal and the operating state of the engine; a target natural gas injection amount determination module, configured to determine a target natural gas injection amount based on the actual air amount, the actual excess air coefficient of the previous control cycle, the target excess air coefficient, the engine speed signal, and the air-fuel ratio; a target throttle opening determination module, configured to determine a target throttle opening according to the target air volume; a real-time control module configured to adjust the target natural gas injection amount in real time based on the target natural gas injection amount, determine a target natural gas injection timing and a target natural gas injection pulse width based on the real-time adjusted target natural gas injection amount and the engine speed signal, and control natural gas combustion based on the target throttle opening, the target natural gas injection timing, and the target natural gas injection pulse width, and obtain in real time an actual excess air coefficient of a current control cycle, so that a difference between the real-time obtained actual excess air coefficient of the current control cycle and the target excess air coefficient falls within a preset excess air coefficient threshold range; The target air volume determination module is specifically configured to: obtain an intake manifold temperature signal; determine a target torque based on a first correspondence relationship according to an engine accelerator pedal signal; the first correspondence relationship being a preset correspondence relationship between the engine accelerator pedal signal and the target torque; determining a target air charge based on a second correspondence according to the target torque and the engine speed signal; The second correspondence is a preset correspondence between the target torque, the engine speed signal, and the target air charge; determining an actual air charge according to the air mass under the intake manifold pressure signal and the intake manifold temperature signal and the air mass under a preset standard state; determining a target air volume according to the target air volume and the actual air volume based on a first calculation formula; The first calculation formula is: ;in, is the target air volume, To target air charge, is the actual air charge, and is the charge adjustment coefficient, is the charge-to-flow coefficient.

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