A supercharging matching method for increasing the supercharging benefit of a single-cylinder hydrogen internal combustion engine

Abstract

The present invention discloses a supercharging matching method for increasing the supercharging benefit of a single-cylinder hydrogen internal combustion engine, belonging to the technical field of single-cylinder hydrogen internal combustion engine optimization. The supercharging matching method for increasing the supercharging benefit of a single-cylinder hydrogen internal combustion engine includes the following steps: calculating the rotational speed of the hydrogen internal combustion engine or the intake duct length based on the intake resonance relationship of the internal combustion engine; calculating the intake air mass flow rate corresponding to the rotational speed of the hydrogen internal combustion engine according to the rotational speed of the hydrogen internal combustion engine and the designed power; matching the operating MAP of the compressor according to the intake air mass flow rate and the supercharging system pressure ratio to determine the rotational speed of the compressor; and selecting a supercharging method. By using the supercharging matching method for increasing the supercharging benefit of a single-cylinder hydrogen internal combustion engine described in the present invention, the intake resonance effect caused by the intake pulse of the single-cylinder hydrogen internal combustion engine is fully utilized, the intake loss caused by supercharging is minimized to the greatest extent, and the goal of enhancing the supercharging benefit of the single-cylinder hydrogen internal combustion engine is achieved; and the compressor always operates at the best efficiency point, ensuring a high system efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of single-cylinder hydrogen internal combustion engine optimization, and particularly to a supercharging matching method for increasing the supercharging benefit of a single-cylinder hydrogen internal combustion engine. Background Art

[0002] Hydrogen is a clean fuel with zero carbon emissions and is an ideal "green" fuel. According to the reaction equation of hydrogen and air, theoretically, the mass of air required to burn 1 kg of hydrogen is 34.32 kg, which is more than twice that of gasoline (14.8 kg) and twice that of natural gas (17.4 kg). Therefore, the demand for air volume by a hydrogen internal combustion engine is much greater than that of gasoline and natural gas, and intake supercharging is a very effective way to increase the intake air volume of an internal combustion engine. There is an urgent need for intake supercharging in a hydrogen internal combustion engine.

[0003] For a multi-cylinder hydrogen internal combustion engine, the commonly used supercharging technology is exhaust gas turbocharging, and the exhaust gas turbocharging technology has also matured. However, for a single-cylinder hydrogen internal combustion engine, due to the unique working mode of the gas, the intake stroke and the exhaust stroke are not affected by other cylinders and are completely independent. Therefore, it is difficult to use the exhaust gas turbocharging technology on a single-cylinder hydrogen internal combustion engine. Therefore, the natural aspiration intake method is more common for a single-cylinder internal combustion engine.

[0004] For a single-cylinder hydrogen internal combustion engine, it is urgent to change from natural aspiration to supercharged intake to increase the power density. However, based on the existing single-cylinder engine industrial system, in order to control the development cost and shorten the development cycle, without new design of the complex cylinder head intake port, the intake supercharging causes an increase in the intake air flow and velocity, an increase in the intake resistance of the intake system, an increase in the pumping loss during the intake process, and a reduction in the benefit brought by supercharging, which is not conducive to the improvement of the system efficiency. In order to increase the power output of a single-cylinder hydrogen internal combustion engine under the existing single-cylinder engine system, supercharging of the single-cylinder hydrogen internal combustion engine is imperative. At the same time, in order to reduce the intake loss brought by supercharging, there is an urgent need for a supercharging matching method to increase the supercharging benefit of a single-cylinder hydrogen internal combustion engine. Summary of the Invention

[0005] The purpose of the present invention is to provide a supercharging matching method for increasing the supercharging benefit of a single-cylinder hydrogen internal combustion engine, which makes full use of the intake resonance effect caused by the intake pulse of the single-cylinder hydrogen internal combustion engine, minimizes the intake loss brought by supercharging to the greatest extent without changing the intake system of the prototype machine, and achieves the goal of enhancing the supercharging benefit of the single-cylinder hydrogen internal combustion engine; and enables the compressor to always work at the best efficiency point to ensure a high system efficiency.

[0006] To achieve the above purpose, the present invention provides a supercharging matching method for increasing the supercharging benefit of a single-cylinder hydrogen internal combustion engine, including the following steps:

[0007] S1. Calculate the rotational speed of the hydrogen internal combustion engine or the length of the intake port based on the intake resonance relationship of the internal combustion engine.

[0008] Intake resonance is a significant feature in the intake of a single-cylinder engine. To reduce the intake loss during the supercharging process of a single-cylinder hydrogen internal combustion engine, the intake resonance should be fully utilized.

[0009] In one working cycle, the calculation formula for the number of times the air flow in the intake port resonates due to the intake pulse is:

[0010] ;

[0011] where, is the number of times the air flow in the intake port resonates, is the working cycle period of the single-cylinder hydrogen internal combustion engine, is the resonance wave period in the intake port.

[0012] In the intake port, the air flow velocity can be considered as the local speed of sound, and its calculation formula is:

[0013] ;

[0014] where, is the local speed of sound in the intake port, that is, the air flow velocity; is the adiabatic index, for air ; is the ideal gas constant, for air J / (kg·K); is the intake temperature, with the unit of K.

[0015] During the operation of the hydrogen internal combustion engine, the distance traveled by the pressure wave in the intake port to complete one oscillation under the influence of the intake pulse is twice the length of the intake port. When the intake pulse resonance wave propagates in the intake port at the local speed of sound, the calculation expression for the resonance wave period is:

[0016] ;

[0017] where, is the length of the intake port of the single-cylinder hydrogen internal combustion engine. The calculation formula for the resonance wave frequency is:

[0018] ;

[0019] where, is the resonance wave frequency.

[0020] The calculation formula for the rotational speed of a four-stroke single-cylinder hydrogen internal combustion engine and the working cycle period is:

[0021] ;

[0022] where, is the operating speed of a single-cylinder hydrogen internal combustion engine, with the unit of r / min. The calculation formula for the intake frequency of a single-cylinder hydrogen internal combustion engine is: ;

[0023] Among them, is the intake frequency of a single-cylinder hydrogen internal combustion engine.

[0024] In a working cycle, the number of times the air flow in the intake passage resonates due to the intake pulse The calculation formula is: ;

[0025] The above formula determines the relationship between the number of resonance times , the intake passage length and the rotational speed of the hydrogen internal combustion engine . Only when takes a positive integer value, that is ( is a positive integer), the intake resonance wave caused by the intake pulse of this cycle can maximize the intake air volume of the next cycle.

[0026] When there are no strict numerical requirements for the rotational speed of the hydrogen internal combustion engine, such as when used as a range extender, the operating speed of the hydrogen internal combustion engine can be determined according to the intake passage length of the hydrogen internal combustion engine prototype and the intake resonance relationship, so as to make full use of intake resonance and increase the supercharging benefit. When there are strict numerical requirements for the rotational speed of the hydrogen internal combustion engine, such as when used as a generator, restricted by the power generation frequency requirement and having strict restrictions on the rotational speed, then the intake passage length can be calculated according to the operating speed and the intake resonance relationship, and the intake passage of the prototype engine except for the cylinder head can be designed. This design is much easier than designing the intake air flow passage in the cylinder head, so as to make full use of intake resonance and increase the supercharging benefit.

[0027] S2. Calculate the intake air mass flow corresponding to the rotational speed of the hydrogen internal combustion engine according to the rotational speed and design power of the hydrogen internal combustion engine.

[0028] First, calculate the calorific value of the mixture per unit time from the design power and thermal efficiency of the hydrogen internal combustion engine. The specific calculation formula is:

[0029] ;

[0030] Among them, is the calorific value of the mixture per unit time, P is the design power of a single-cylinder hydrogen internal combustion engine, is the design thermal efficiency of the hydrogen internal combustion engine.

[0031] According to the reaction equation of the hydrogen-air mixture, calculate the air mass flow rate corresponding to the calorific value per unit time. The expression of the reaction equation of the hydrogen-air mixture is:

[0032] ;

[0033] Among them, is the excess air coefficient during the operation of a single-cylinder hydrogen internal combustion engine. Therefore, the calculation formula for the air mass flow rate is:

[0034] ;

[0035] Among them, is the intake air mass flow rate during the operation of a single-cylinder hydrogen internal combustion engine; is the calorific value per unit mass of hydrogen, is 120 MJ / kg.

[0036] S3. According to the intake air mass flow rate and the pressure ratio of the supercharging system, match the compressor operating MAP and determine the compressor speed.

[0037] Based on the calculated air mass flow rate, input the air flow rate in the naturally aspirated state of the prototype at the current speed, and thus calculate the pressure ratio. The calculation formula is:

[0038] ;

[0039] Among them, is the required pressure ratio, is the air mass flow rate of the prototype in the naturally aspirated state at the corresponding speed n.

[0040] Match the compressor operating MAP according to the calculated intake air flow rate and pressure ratio. The expression of the compressor operating MAP is:

[0041] ;

[0042] Among them, is the compressor operating efficiency, is the compressor operating speed, is the air mass flow rate flowing through the compressor, is the pressure ratio, is the mapping relationship between the compressor operating efficiency and the air mass flow rate and pressure ratio, is the mapping relationship between the speed and the air mass flow rate and pressure ratio, is the intake air mass flow rate at the matching point.

[0043] Taking the air flow rate and pressure ratio as input conditions, the matching principle is to make the point determined by the input air flow rate and pressure ratio appear in the region with the highest compressor efficiency, so as to obtain the corresponding compressor speed , the calculation formula is:

[0044] .

[0045] S4. Select the boost mode.

[0046] After completing the boost MAP matching, the boost system can be designed according to different boost methods.

[0047] When the supercharging method is mechanical supercharging, the speed of the hydrogen internal combustion engine and the speed of the compressor are input to calculate the transmission speed ratio of the mechanical supercharging system. The calculation formula is:

[0048] ;

[0049] in, is the transmission ratio of the supercharger transmission system, is the compressor speed, is the speed of the hydrogen internal combustion engine. Design a mechanical supercharger transmission system to achieve constant speed operation of the compressor so that it always operates at the highest efficiency point to ensure high system efficiency.

[0050] When electric supercharging is selected, the compressor speed is input to complete the design of the electric supercharging control subsystem, and the constant speed control of electric supercharging is realized, so that the compressor always works at the highest efficiency point to ensure higher system efficiency.

[0051] Complete supercharging matching to enhance the supercharging benefit of a single-cylinder hydrogen internal combustion engine.

[0052] The advantages and positive effects of the boost matching method for increasing the boost benefit of a single-cylinder hydrogen internal combustion engine described in the present invention are: on the one hand, the intake resonance effect caused by the intake pulse of the single-cylinder hydrogen internal combustion engine is fully utilized to minimize the intake loss caused by the boost, thereby achieving the goal of enhancing the boost benefit of the single-cylinder hydrogen internal combustion engine. On the other hand, the compressor is always operated at the optimal efficiency point to ensure a higher system efficiency.

[0053] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 It is the overall flow chart of the present invention;

[0055] Figure 2 It is a schematic diagram of the resonance of the intake pulse and the pressure wave in the intake passage of the single-cylinder hydrogen internal combustion engine of the present invention;

[0056] Figure 3 This is a flow chart of calculating the speed of a hydrogen internal combustion engine in step S1 of the present invention;

[0057] Figure 4Flow chart for calculating the intake duct length in step S1 of the present invention;

[0058] Figure 5 Flow chart for calculating the intake air mass flow rate in step S2 of the present invention;

[0059] Figure 6 Flow chart for matching the compressor operating MAP in step S3 of the present invention;

[0060] Figure 7 Schematic diagram of supercharging matching in the first embodiment of the present invention;

[0061] Figure 8 Flow chart for selecting the supercharging method in step S4 of the present invention;

[0062] Figure 9 Schematic diagram of supercharging matching in the second embodiment of the present invention. Detailed implementation manners

[0063] In this application, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. In case of inconsistency, the meaning described in this specification or the meaning derived from the content recorded in this specification shall prevail. Additionally, the terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application. For the purpose of accurately describing the technical content in this application and for accurately understanding the present invention, the following explanations or definitions of the terms used in this specification are given before describing the detailed implementation manners:

[0064] 1) Hydrogen internal combustion engine: It refers to an internal combustion engine that uses hydrogen as fuel. By mixing hydrogen and air and then burning, it drives the piston to reciprocate. The piston pushes the connecting rod, and the connecting rod drives the crankshaft to rotate, thereby outputting rotational power. Different from a hydrogen fuel cell, a hydrogen fuel cell is a power generation device that directly converts the chemical energy of hydrogen and oxygen into electrical energy.

[0065] 2) Intake resonance: In the intake system, when air flows through the pipeline, due to the air flow velocity and the geometric shape of the pipeline, pressure waves will be generated inside the pipeline. Due to the relationship between the pipeline length of the intake system and the operating frequency (i.e., rotational speed) of the engine, these pressure waves will reflect and superimpose, thus forming a "resonance" phenomenon.

[0066] 3) Completing one resonance: Inside the intake duct, the process in which the pressure wave caused by the intake pulse propagates from the intake valve to the resonance chamber and then back to the intake valve in the intake duct is defined as completing one resonance.

[0067] 4) Intake duct length: The distance that the air flow travels between the valve of a single-cylinder engine and the pressure stabilizing chamber.

[0068] 5) Stabilizing pressure chamber: A space or environment where the air pressure remains constant during the intake process of a hydrogen internal combustion engine, generally a gas storage space with a relatively large displacement relative to the cylinder.

[0069] 6) Resonance relationship formula: An expression that determines the relationship between the resonance times, intake duct length, and rotational speed of a hydrogen internal combustion engine.

[0070] 7) Pressure ratio: The ratio of the outlet pressure to the inlet pressure of a compressor.

[0071] 8) Compressor MAP: A contour plot of the working efficiency and rotational speed of a compressor with air flow rate as the horizontal axis and pressure ratio as the vertical axis, which can fully describe the working state and characteristics of the compressor.

[0072] The following will describe the embodiments of the present invention in detail with reference to the accompanying drawings.

[0073] Embodiment 1

[0074] As Figure 1 shown. A supercharging matching method for increasing the supercharging benefit of a single-cylinder hydrogen internal combustion engine includes the following steps:

[0075] S1. Based on the intake resonance relationship formula of the internal combustion engine, calculate the rotational speed or intake duct length of the hydrogen internal combustion engine.

[0076] As Figure 2 shown. In one working cycle, is the number of times the reflected wave resonates. It can be seen from the figure that only when the number of resonance times is a positive integer, the intake resonance caused by the intake pulse of the previous cycle can play the maximum role in the intake of the next cycle, increasing the intake air volume. Thus, the relationship formula among the resonance times, intake duct length, and rotational speed of the single-cylinder hydrogen internal combustion engine is determined and expressed as:

[0077] ;

[0078] Among them, is the working cycle period of the single-cylinder hydrogen internal combustion engine, is the resonance wave period in the intake duct, is the resonance wave frequency, is the intake frequency of the single-cylinder hydrogen internal combustion engine; is the local sound speed in the intake duct, that is, the air flow velocity; is the intake duct length of the single-cylinder hydrogen internal combustion engine, is the working rotational speed of the single-cylinder hydrogen internal combustion engine.

[0079] As Figure 3 shown. When the single-cylinder hydrogen internal combustion engine is used as a range extender, it includes the following steps:

[0080] S111: Input the intake conditions during the working process of the single-cylinder hydrogen internal combustion engine, including the intake temperatureT , the ideal gas constant R (for air, J / (kg·K)) and the adiabatic index , for air .

[0081] S112: Calculate the local speed of sound in the intake passage, which is the air flow velocity , and the calculation formula is:

[0082] .

[0083] S113: Input the intake resonance relationship, and the expression is:

[0084] .

[0085] S114: Input the resonance times , which is a positive integer.

[0086] S115: Input the length of the intake passage of the single-cylinder hydrogen internal combustion engine L .

[0087] S116: Obtain the rotational speed of the single-cylinder hydrogen internal combustion engine .

[0088] As Figure 4 shown. When the single-cylinder engine is used as a fixed-frequency generator, it includes the following steps:

[0089] S121: Input the rotational speed of the hydrogen internal combustion engine , and this rotational speed is determined by the frequency required for fixed-frequency power generation.

[0090] S122: Input the intake resonance relationship, and the expression is:

[0091] .

[0092] S123: Input the resonance times , which is a positive integer.

[0093] S124: Input the intake conditions during the operation of the single-cylinder hydrogen internal combustion engine, including the intake temperature T , the ideal gas constant R (for air, J / (kg·K)) and the adiabatic index .

[0094] S125: Calculate the local speed of sound in the intake passage, and the calculation formula is:

[0095] .

[0096] S126: Obtain the length of the intake passageL , complete the design of the intake duct length.

[0097] S2. Calculate the intake air mass flow rate corresponding to the hydrogen internal combustion engine speed based on the hydrogen internal combustion engine speed and the designed power.

[0098] As Figure 5 shown. After determining the operating speed of the single-cylinder hydrogen internal combustion engine, the specific calculation process of the intake air mass flow rate corresponding to the hydrogen internal combustion engine speed is as follows:

[0099] S201: Input the designed power of the single-cylinder hydrogen internal combustion engine P .

[0100] S202: Input the designed efficiency of the hydrogen internal combustion engine .

[0101] S203: Calculate the calorific value of the fuel-air mixture per unit time, and the calculation formula is:

[0102] ;

[0103] where is the calorific value of the fuel-air mixture per unit time.

[0104] S204: Input the designed excess air coefficient of the hydrogen-air mixture .

[0105] S205: Calculate the intake air flow rate of the supercharged single-cylinder hydrogen internal combustion engine, and the calculation formula is:

[0106] ;

[0107] where is the air mass flow rate during the operation of the single-cylinder hydrogen internal combustion engine, is the lower calorific value per unit mass of hydrogen, which is 120 MJ / kg.

[0108] S206: Input the operating speed of the hydrogen internal combustion engine .

[0109] S207: Obtain the air mass flow rate of the naturally aspirated prototype engine at the speed of .

[0110] S208: Calculate the pressure ratio of the supercharging system, and the calculation expression is:

[0111] ;

[0112] where is the required supercharging ratio.

[0113] S3. Determine the compressor speed by matching the compressor operating MAP according to the intake air mass flow rate and the supercharging system pressure ratio.

[0114] As Figure 6 shown. The specific process of matching the compressor operating MAP is as follows:

[0115] S301: Determine the supercharging matching principle as matching the intake air flow rate and the supercharging ratio to the best thermal efficiency operating point of the compressor.

[0116] S302: Input the intake air mass flow rate of a single-cylinder hydrogen internal combustion engine .

[0117] S303: Input the supercharging system pressure ratio .

[0118] S304: Match the compressor MAP. The expression of the compressor MAP is:

[0119] ;

[0120] where is the compressor operating efficiency, is the compressor operating speed, is the flow rate through the compressor, is the supercharging ratio, and are the mapping relationships of the compressor operating efficiency and speed with the flow rate and pressure ratio respectively.

[0121] The matching method expression is:

[0122] ;

[0123] S305: Calculate the compressor speed from the compressor MAP expression. The expression:

[0124] ;

[0125] where is the compressor speed.

[0126] The schematic diagram of supercharging matching is as Figure 7 shown.

[0127] The main body of the schematic diagram is the MAP diagram of a general compressor, which contains normalized flow rate, pressure ratio, efficiency and speed data. The air mass flow rate and pressure ratio input by S302 and S303 are used to match the compressor efficiency. When the matched compressor efficiency is the maximum operating efficiency point in the compressor MAP, the compressor corresponding to the current compressor MAP is considered to be the required matched compressor, and its corresponding efficiency is Figure 7The efficiency corresponding to the "pentagram" in the figure is used to implement S305 to determine the operating speed of the compressor. .

[0128] S4. Select the supercharging method.

[0129] As Figure 8 shown. The specific process of selecting the supercharging method is as follows:

[0130] S401: Select the supercharging method, including two methods: mechanical supercharging and electric supercharging.

[0131] S402: Select mechanical supercharging, and the implementation process includes the steps of S403, S404, S405, and S406.

[0132] S403: Input the rotational speed of the single-cylinder hydrogen internal combustion engine .

[0133] S404: Input the rotational speed of the compressor .

[0134] S405: Calculate the speed ratio of the mechanical supercharging transmission system, and the calculation formula is:

[0135] ;

[0136] where is the transmission ratio of the mechanical supercharging system.

[0137] S406: Design the mechanical supercharging transmission system with the obtained transmission ratio to achieve constant rotational speed control of the compressor.

[0138] S407: Select the supercharging method as electric supercharging, and the implementation process includes the steps of S408, S409, and S410.

[0139] S408: Input the rotational speed of the compressor .

[0140] S409: Design the power supply system for electric supercharging.

[0141] S410: Design the rotational speed control system for the electric compressor to achieve constant rotational speed control of the compressor.

[0142] During the implementation process, the intake resonance effect caused by the intake pulse of the single-cylinder hydrogen internal combustion engine is fully utilized. Under the condition of minimizing the change of the intake system of the prototype machine to the greatest extent, the intake loss caused by supercharging is minimized to achieve the goal of enhancing the supercharging benefit of the single-cylinder hydrogen internal combustion engine and ensuring a high system efficiency.

[0143] Embodiment 2

[0144] A supercharging matching method for increasing the supercharging benefit of a single-cylinder hydrogen internal combustion engine includes the following steps:

[0145] S1. Calculate the rotational speed of the hydrogen internal combustion engine or the length of the intake passage based on the intake resonance relationship of the internal combustion engine.

[0146] As Figure 2 shown. In one working cycle, 1, 2, …, is the number of times the reflected wave resonates. It can be seen from the figure that only when the number of resonance times is a positive integer can the intake resonance caused by the intake pulse of the previous cycle play the maximum role in the intake of the next cycle, increasing the intake air volume. Thus, the relationship between the number of resonance times, the length of the intake passage, and the rotational speed of the single-cylinder hydrogen internal combustion engine is determined and expressed as:

[0147] ;

[0148] Among them, is the working cycle period of the single-cylinder hydrogen internal combustion engine, is the resonance wave period in the intake passage, is the resonance wave frequency, is the intake frequency of the single-cylinder hydrogen internal combustion engine; is the local sound speed in the intake passage, that is, the air flow velocity; is the length of the intake passage of the single-cylinder hydrogen internal combustion engine, is the working rotational speed of the single-cylinder hydrogen internal combustion engine.

[0149] As Figure 3 shown. When a single-cylinder hydrogen internal combustion engine with an intake passage length of 0.3 m and a displacement of 250 cc is used as a motorcycle range extender, it includes the following steps:

[0150] S111: Input the intake conditions during the working process of the single-cylinder hydrogen internal combustion engine, including the intake temperature T = 300 K, the ideal gas constant R (for air, J / (kg·K)), and the adiabatic index , for air .

[0151] S112: Calculate the local sound speed in the intake passage, which is the air flow velocity u , and the calculation formula is:

[0152] 。

[0153] S113: Input the intake resonance relationship, and the expression is:

[0154] ;

[0155] S114: Input the number of resonance times .

[0156] S115: Intake duct length of the single-cylinder hydrogen internal combustion engine L = 0.3 m.

[0157] S116: Obtain the rotational speed of the single-cylinder hydrogen internal combustion engine , that is, when the supercharged single-cylinder hydrogen internal combustion engine is used as a range extender for a motorcycle, its rotational speed should be designed to operate at a constant rotational speed of 6944 r / min to increase the supercharging benefit.

[0158] Such as Figure 4 shown. When a single-cylinder hydrogen internal combustion engine with a displacement of 250 cc is used as a fixed-frequency generator, when the rotational speed requirement of the hydrogen internal combustion engine is 6000 r / min, it includes the following steps:

[0159] S121: Input the rotational speed of the hydrogen internal combustion engine .

[0160] S122: Input the intake resonance relationship formula, and the expression is:

[0161] .

[0162] S123: Input the resonance times .

[0163] S124: Input the intake conditions during the operation of the single-cylinder hydrogen internal combustion engine, including the intake temperature T = 300 K, the ideal gas constant R (for air, J / (kg·K)) and the adiabatic index (for air .

[0164] S125: Calculate the local speed of sound in the intake duct, and the calculation formula is:

[0165] .

[0166] S126: Obtain the intake duct length L = 0.347 m, and complete the design of the intake duct length.

[0167] Taking the single-cylinder hydrogen internal combustion engine used as a fixed-frequency generator as an example, the supercharging matching process is implemented. It should be understood that when the single-cylinder hydrogen internal combustion engine is used as a range extender, except for the different calculated values, the other implementation processes are the same.

[0168] S2. According to the rotational speed and design power of the hydrogen internal combustion engine, calculate the intake air mass flow corresponding to the rotational speed of the hydrogen internal combustion engine.

[0169] The designed power of this supercharged single-cylinder hydrogen internal combustion engine is 15 kW, the designed thermal efficiency is 32%, and the designed excess air ratio is 2 to achieve lower NOx emissions.

[0170] As Figure 5 shown. After determining the operating speed of the single-cylinder hydrogen internal combustion engine, the specific calculation process of the intake air mass flow corresponding to the hydrogen internal combustion engine speed is as follows:

[0171] S201: Input the designed power of the single-cylinder hydrogen internal combustion engine P = 15 kW.

[0172] S202: Input the designed efficiency of the hydrogen internal combustion engine .

[0173] S203: Calculate the calorific value of the air-fuel mixture per unit time, and the calculation formula is:

[0174] ;

[0175] where is the calorific value of the air-fuel mixture per unit time.

[0176] S204: Input the designed excess air ratio of the hydrogen-air mixture .

[0177] S205: Calculate the intake air flow of the supercharged single-cylinder hydrogen internal combustion engine, and the calculation formula is:

[0178] ;

[0179] where is the air mass flow during the operation of the single-cylinder hydrogen internal combustion engine, is the lower calorific value per unit mass of hydrogen, which is 120 MJ / kg.

[0180] S206: Input the operating speed of the hydrogen internal combustion engine .

[0181] S207: Obtain the air mass flow of the naturally aspirated prototype at the speed of .

[0182] S208: Calculate the pressure ratio of the supercharging system, and the calculation expression is:

[0183] ;

[0184] where is the required supercharging ratio.

[0185] S3. According to the intake air mass flow and the pressure ratio of the supercharging system, match the working MAP of the compressor and determine the compressor speed.

[0186] As Figure 6 shown. The specific process of matching the compressor operating MAP is as follows:

[0187] S301: Determine the supercharging matching principle as matching the intake air flow rate and supercharging ratio to the best thermal efficiency operating point of the compressor.

[0188] S302: Input the intake air mass flow rate of the single-cylinder hydrogen internal combustion engine .

[0189] S303: Input the supercharging system pressure ratio .

[0190] S304: Match the compressor MAP. The compressor MAP expression is:

[0191] ;

[0192] where is the compressor operating efficiency, is the compressor operating speed, is the flow rate through the compressor, is the supercharging ratio, and are the mapping relationships of the compressor operating efficiency and speed with the flow rate and pressure ratio respectively.

[0193] The matching method expression is:

[0194] ;

[0195] S305: Calculate the compressor speed from the compressor MAP expression. The expression:

[0196] ;

[0197] where is the compressor speed.

[0198] The schematic diagram of supercharging matching is as Figure 9 shown.

[0199] The main body of the schematic diagram is the MAP diagram of a general compressor, which includes the flow rate, pressure ratio, efficiency, and speed data of the compressor. The air mass flow rate and pressure ratio input by S302 and S303 are used to match the compressor efficiency. When the matched compressor efficiency is the maximum operating efficiency point in the compressor MAP, it is considered that the compressor corresponding to the current compressor MAP is the required matched compressor, and its corresponding efficiency is the efficiency corresponding to the "pentagram" in Figure 9 . Thus, S305 is implemented to determine the operating speed of the compressor .

[0200] S4. Select the supercharging method.

[0201] As Figure 8 shown. The specific process of selecting the supercharging method is as follows:

[0202] S401: Select the supercharging method, including two methods: mechanical supercharging and electric supercharging.

[0203] S402: Select mechanical supercharging, and the implementation process includes the steps of S403, S404, S405, and S406.

[0204] S403: Input the rotational speed of the single-cylinder hydrogen internal combustion engine .

[0205] S404: Input the rotational speed of the compressor .

[0206] S405: Calculate the speed ratio of the mechanical supercharging transmission system, and the calculation formula is:

[0207] ;

[0208] wherein, is the transmission ratio of the mechanical supercharging system.

[0209] S406: Design the mechanical supercharging transmission system with the obtained speed ratio to achieve constant rotational speed control of the compressor.

[0210] S407: Select the supercharging method as electric supercharging, and the implementation process includes the steps of S408, S409, and S410.

[0211] S408: Input the rotational speed of the compressor .

[0212] S409: Design the power supply system for electric supercharging.

[0213] S410: Design the rotational speed control system of the electric compressor to achieve constant rotational speed control of the compressor.

[0214] During the implementation process, the intake resonance effect caused by the intake pulse of the single-cylinder hydrogen internal combustion engine is fully utilized. Under the condition of minimizing the change of the intake system of the prototype machine to the greatest extent, the intake loss caused by supercharging is minimized to the greatest extent, the goal of enhancing the supercharging benefit of the single-cylinder hydrogen internal combustion engine is achieved, and a high system efficiency is ensured.

[0215] Therefore, by adopting the supercharging matching method for enhancing the supercharging benefit of the single-cylinder hydrogen internal combustion engine described in the present invention, the intake resonance effect caused by the intake pulse of the single-cylinder hydrogen internal combustion engine is fully utilized, the intake loss caused by supercharging is minimized to the greatest extent, and the goal of enhancing the supercharging benefit of the single-cylinder hydrogen internal combustion engine is achieved; and the compressor always operates at the best efficiency point, ensuring a high system efficiency.

[0216] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A supercharging matching method for increasing the supercharging benefit of a single-cylinder hydrogen internal combustion engine, characterized in that, It includes the following steps: S1. Calculate the hydrogen internal combustion engine speed or the intake duct length based on the intake resonance relationship of the internal combustion engine; S2. Calculate the intake air mass flow rate corresponding to the hydrogen internal combustion engine speed according to the hydrogen internal combustion engine speed and the designed power; S3. Match the compressor operating MAP according to the intake air mass flow rate and the supercharger pressure ratio, and determine the compressor speed; S4. Select the supercharging method; In S2, the calculation expression for the intake air mass flow rate is: ； Among them, is the intake air mass flow rate during the operation of a single-cylinder hydrogen internal combustion engine; is the calorific value of the air-fuel mixture per unit time, is the calorific value per unit mass of hydrogen, is the excess air coefficient of the hydrogen-air mixture reaction, P is the designed power of a single-cylinder hydrogen internal combustion engine, is the designed thermal efficiency of a hydrogen internal combustion engine; In the step S3, according to the best efficiency point matching principle, the compressor operating MAP is matched. The mathematical expression of the best efficiency point matching principle is: ; Among them, is the compressor working efficiency, is the compressor working speed, is the air mass flow rate through the compressor, is the pressure ratio, is the mapping relationship between the compressor working efficiency, air mass flow rate and pressure ratio, is the mapping relationship between the speed, air mass flow rate and pressure ratio, is the intake air mass flow rate at the matching point, is the pressure ratio at the matching point; In S3, the calculation expression for the supercharger pressure ratio is: ； Among them, is the pressure ratio, is the air mass flow rate of the prototype under naturally aspirated condition.

2. A supercharging matching method for increasing the supercharging benefit of a single-cylinder hydrogen internal combustion engine according to claim 1, characterized in that In S1, the intake resonance relationship among the intake resonance times, the intake duct length and the hydrogen internal combustion engine speed is: ； Among them, is the intake resonance frequency, is the adiabatic index, is the ideal gas constant, is the intake temperature, is the intake port length, is the rotational speed of the hydrogen internal combustion engine; Utilize the intake resonance caused by the intake pulse of the hydrogen internal combustion engine to reduce the intake resistance brought by supercharging.

3. The supercharging matching method for increasing the supercharging benefit of a single-cylinder hydrogen internal combustion engine according to claim 2, characterized in that, The said is a positive integer.

4. A supercharging matching method for increasing the supercharging benefit of a single-cylinder hydrogen internal combustion engine according to claim 3, characterized in that When the hydrogen internal combustion engine is used as a range extender, calculate the hydrogen internal combustion engine speed according to the intake duct length through the intake resonance relationship.

5. A supercharging matching method for increasing the supercharging benefit of a single-cylinder hydrogen internal combustion engine according to claim 4, characterized in that When the hydrogen internal combustion engine is used as a fixed-frequency generator, calculate the intake duct length according to the hydrogen internal combustion engine speed required by the power generation frequency through the intake resonance relationship.

6. A supercharging matching method for increasing the supercharging benefit of a single-cylinder hydrogen internal combustion engine according to claim 5, characterized in that, In S4, when mechanical supercharging is selected, the calculation formula for the transmission ratio of the supercharging transmission system is: ； Among them, is the transmission ratio of the supercharger transmission system, is the compressor speed, is the hydrogen internal combustion engine speed.

7. A supercharging matching method for increasing the supercharging benefit of a single-cylinder hydrogen internal combustion engine according to claim 6, characterized in that In S4, when electric supercharging is selected, the rotational speed of the compressor is used Design an electric supercharging control system to achieve constant rotational speed control of the electric supercharging compressor.

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