A Lambda correction system for a hydrogen engine

Abstract

This invention discloses a lambda correction system for hydrogen engines, used for air-fuel ratio correction calculations in hydrogen engines, for use in the verification of immature hydrogen engines. The system is characterized by comprising an open-loop correction unit for outputting the lambda correction value for the open-loop portion and a closed-loop correction unit for outputting the lambda correction value for the closed-loop portion. The invention has the following beneficial effects: During the experimental phase of hydrogen engine development, an open-loop correction value for the air-fuel ratio is determined based on four criteria, facilitating experiments without accurate oxygen sensor feedback; an air-fuel ratio correction factor influenced by start time and water temperature is introduced to increase calculation accuracy; and an air-fuel ratio correction factor for hydrogen injection and rail pressure is introduced to enhance hydrogen combustion safety.

Description

Technical Field

[0001] The present invention relates to a Lambda correction scheme for a hydrogen engine. Background Art

[0002] A hydrogen engine is an engine that uses hydrogen as an internal combustion engine fuel, also known as a "hydrogen fuel engine." Because hydrogen contains no carbon, it produces no CO2 upon combustion, and can be obtained from renewable energy sources such as solar and wind power. Therefore, it is considered an ideal energy source or energy carrier. When used as an internal combustion engine fuel, hydrogen easily achieves lean burn, emits few pollutants, and has high thermal efficiency. However, the application of hydrogen engines is currently still in the experimental and verification stage, but increasingly stringent emission standards make the verification and application of hydrogen engines imperative. Due to hydrogen's instability and the requirements for intake air, special judgment conditions need to be considered when calculating the air-fuel ratio correction for hydrogen engines. Summary of the Invention

[0003] The purpose of the present invention is to provide an air-fuel ratio correction scheme for a hydrogen engine, which is suitable for use in the experimental stage of a hydrogen engine and allows the open-loop and closed-loop parts to work independently for use in the verification of immature hydrogen engines.

[0004] In order to achieve the above-mentioned purpose, the technical solution of the present invention is to provide a Lambda correction system for a hydrogen engine, which is used for the air-fuel ratio correction calculation of the hydrogen engine and is used for the verification of immature hydrogen engines. It is characterized in that it includes an open-loop correction unit for outputting the open-loop Lambda correction amount and a closed-loop correction unit for outputting the closed-loop Lambda correction amount, wherein the open-loop Lambda correction amount or the closed-loop Lambda correction amount is used as the final Lambda correction value Lambda_CV, or the open-loop Lambda correction amount and the closed-loop Lambda correction amount are added to obtain the final Lambda correction value Lambda_CV.

[0005] Preferably, the open-loop correction unit includes:

[0006] The initial correction module is used to obtain the initial correction value by calibrating the speed of the hydrogen engine and the intake flow of the hydrogen engine through Map;

[0007] Time / water temperature air-fuel ratio correction module, used to obtain the start time / water temperature air-fuel ratio correction;

[0008] The hydrogen injection part Lambda correction module is used to obtain the hydrogen injection part Lambda correction;

[0009] Rail pressure part Lambda correction module, used to obtain rail pressure part Lambda correction;

[0010] The open-loop Lambda correction module is used to obtain the open-loop Lambda correction by adding the initial correction, the start time / water temperature air-fuel ratio correction, the hydrogen injection Lambda correction, and the rail pressure Lambda correction.

[0011] Preferably, the time / water temperature air-fuel ratio correction module obtains the start time / water temperature air-fuel ratio correction by the following steps:

[0012] The starting time of the hydrogen engine is converted by CURVE to obtain the air-fuel ratio correction value affected by the starting time;

[0013] After converting the water temperature through CURVE, the corresponding water temperature correction coefficient is obtained;

[0014] Multiply the air-fuel ratio correction value affected by the start time by the water temperature correction coefficient to obtain the start time / water temperature air-fuel ratio correction amount.

[0015] Preferably, the hydrogen injection part Lambda correction module obtains the hydrogen injection part Lambda correction by the following steps:

[0016] The speed and hydrogen flow of the hydrogen engine are calibrated through Map to obtain the Lambda correction value of the hydrogen injection part;

[0017] The EGR valve position is converted by Curve and then ramped to obtain the EGR valve position correction coefficient;

[0018] The Lambda correction value of the hydrogen injection part is multiplied by the EGR valve position correction coefficient to obtain the Lambda correction amount of the hydrogen injection part.

[0019] Preferably, the rail pressure Lambda correction module obtains the rail pressure Lambda correction by the following steps:

[0020] The speed and hydrogen flow of the hydrogen engine are calibrated through Map to obtain the Lambda correction value of the hydrogen injection part;

[0021] After the rail pressure is converted into Curve, it is multiplied by the Lambda correction value of the hydrogen injection part to obtain the Lambda correction value of the rail pressure part.

[0022] Preferably, the closed-loop correction unit includes an oxygen sensor range monitoring module and a correction value control module, wherein:

[0023] The oxygen sensor range monitoring module includes:

[0024] The reasonable range detection submodule is used to determine whether the oxygen sensor raw voltage value exceeds a preset reasonable range after obtaining the oxygen sensor raw voltage value. If it exceeds, the closed-loop part Lambda correction amount is directly set to a predetermined calibration value. If it does not exceed, the oxygen sensor raw voltage value is output;

[0025] The Lambda measurement value acquisition submodule is used to convert the original voltage value of the oxygen sensor output by the reasonable range detection submodule into the Lambda measurement value, and obtain the final Lambda measurement value of the oxygen sensor after PT1 filtering;

[0026] The implementation of the correction value control module includes the following steps:

[0027] Step 1: Preset a Lambda range based on the design value of the hydrogen engine's air-fuel ratio:

[0028] If the Lambda measurement value obtained by the oxygen sensor range monitoring module is within the Lambda range, it is determined that the Lambda value is in the Normal state and the process goes to step 2;

[0029] If the Lambda measurement value obtained by the oxygen sensor range monitoring module exceeds the Lambda range, proceed to step 3;

[0030] Step 2: Set the closed-loop Lambda correction to 0;

[0031] Step 3: In the first step, the closed-loop Lambda correction value is stepped to the scalable value LamdaPosStep_C, and then gradually ramped until the closed-loop Lambda correction value reaches the upper limit of the closed-loop correction value. Each time the closed-loop Lambda correction value is updated, the closed-loop Lambda correction value is output.

[0032] The present invention has the following beneficial effects:

[0033] 1) During the test phase of hydrogen engine development, four judgment conditions are used to provide an open-loop correction value for the air-fuel ratio, facilitating experiments in environments without accurate oxygen sensor feedback;

[0034] 2) Introduced air-fuel ratio correction for the influence of starting time and water temperature to increase calculation accuracy;

[0035] 3) An air-fuel ratio correction value for the hydrogen injection / rail pressure part is introduced to enhance the safety of hydrogen combustion. DETAILED DESCRIPTION

[0036] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0037] The present invention discloses a lambda correction system for a hydrogen engine, comprising an open-loop correction unit and a closed-loop correction unit. The open-loop lambda correction value provided by the open-loop correction unit and the closed-loop lambda correction value provided by the closed-loop correction unit can be independently effective, with either the open-loop lambda correction value or the closed-loop lambda correction value serving as the final lambda correction value Lambda_CV. The open-loop lambda correction value provided by the open-loop correction unit and the closed-loop lambda correction value provided by the closed-loop correction unit can also act together, with the open-loop lambda correction value and the closed-loop lambda correction value added to obtain the final lambda correction value Lambda_CV.

[0038] The implementation of the open-loop correction unit includes the following steps:

[0039] Step 1: Obtain an initial correction value by calibrating the speed of the hydrogen engine and the intake flow rate of the hydrogen engine through a Map.

[0040] Step 2: Convert the starting time of the hydrogen engine into CURVE to obtain the air-fuel ratio correction value affected by the starting time;

[0041] After converting the water temperature through CURVE, the corresponding water temperature correction coefficient is obtained;

[0042] Multiply the air-fuel ratio correction value affected by the start time by the water temperature correction coefficient to obtain the start time / water temperature air-fuel ratio correction amount.

[0043] Step 3: The speed of the hydrogen engine and the hydrogen flow rate of the hydrogen engine are calibrated through Map to obtain the Lambda correction value of the hydrogen injection part;

[0044] The EGR valve position is converted by Curve and then ramped to obtain the EGR valve position correction coefficient;

[0045] The Lambda correction value of the hydrogen injection part is multiplied by the EGR valve position correction coefficient to obtain the Lambda correction amount of the hydrogen injection part.

[0046] Step 4: The speed of the hydrogen engine and the hydrogen flow rate of the hydrogen engine are calibrated through Map to obtain the Lambda correction value of the hydrogen injection part;

[0047] After the rail pressure is converted into Curve, it is multiplied by the Lambda correction value of the hydrogen injection part to obtain the Lambda correction value of the rail pressure part.

[0048] Step 5: Add the initial correction amount, the start time / water temperature air-fuel ratio correction amount, the hydrogen injection part Lambda correction amount, and the rail pressure part Lambda correction amount to obtain the open-loop part Lambda correction amount of the hydrogen engine.

[0049] The implementation of the closed-loop correction unit includes the following steps:

[0050] Step 1: Oxygen sensor range monitoring, including:

[0051] Step 101: Obtain the raw voltage value of the oxygen sensor and perform a rationality check on the raw voltage value of the oxygen sensor. If the raw voltage value of the oxygen sensor exceeds the reasonable range, directly set the closed-loop Lambda correction value to a predetermined calibration value. If it does not exceed the reasonable range, proceed to step 102.

[0052] Step 102: Convert the original voltage value of the oxygen sensor into a Lambda measurement value, and obtain the final Lambda measurement value of the oxygen sensor after PT1 filtering.

[0053] Step 2: Correction value control, including:

[0054] Step 201: Preset a Lambda range based on the design value of the hydrogen engine's air-fuel ratio:

[0055] If the Lambda measurement value is within the Lambda range, it is determined that the Lambda value is in the Normal state and the process goes to step 202;

[0056] If the Lambda measurement value exceeds the Lambda range, proceed to step 203;

[0057] Step 202: Set the closed-loop Lambda correction to 0;

[0058] Step 203: In the first step, the closed-loop Lambda correction amount is stepped to the scalable value LamdaPosStep_C, and then gradually ramped until the closed-loop Lambda correction amount reaches the closed-loop correction value upper limit. Each time the closed-loop Lambda correction amount is updated, the closed-loop Lambda correction amount is output.

Claims

1. A lambda correction system for a hydrogen engine, used for air-fuel ratio correction calculation of a hydrogen engine, for use in the verification of immature hydrogen engines, characterized by: comprising an open-loop correction unit for outputting an open-loop portion Lambda correction value and a closed-loop correction unit for outputting a closed-loop portion Lambda correction value, wherein the open-loop portion Lambda correction value or the closed-loop portion Lambda correction value is used as a final Lambda correction value Lambda_CV, or the open-loop portion Lambda correction value and the closed-loop portion Lambda correction value are added to obtain the final Lambda correction value Lambda_CV; The open-loop correction unit comprises: The initial correction module is used to obtain the initial correction value by calibrating the speed of the hydrogen engine and the intake flow of the hydrogen engine through Map; Time / water temperature air-fuel ratio correction module, used to obtain the start time / water temperature air-fuel ratio correction; The hydrogen injection part Lambda correction module is used to obtain the hydrogen injection part Lambda correction; Rail pressure part Lambda correction module, used to obtain rail pressure part Lambda correction; The open-loop Lambda correction module is used to obtain the open-loop Lambda correction by adding the initial correction, the start time / water temperature air-fuel ratio correction, the hydrogen injection Lambda correction, and the rail pressure Lambda correction; The time / water temperature air-fuel ratio correction module obtains the start time / water temperature air-fuel ratio correction using the following steps: The starting time of the hydrogen engine is converted into CURVE to obtain the air-fuel ratio correction value affected by the starting time; After converting the water temperature through CURVE, the corresponding water temperature correction coefficient is obtained; Multiply the air-fuel ratio correction value affected by the starting time by the water temperature correction coefficient to obtain the starting time / water temperature air-fuel ratio correction value; The hydrogen injection part Lambda correction module obtains the hydrogen injection part Lambda correction by the following steps: The speed and hydrogen flow of the hydrogen engine are calibrated through Map to obtain the Lambda correction value of the hydrogen injection part; The EGR valve position is converted by Curve and then ramped to obtain the EGR valve position correction coefficient; Multiplying the Lambda correction value of the hydrogen injection part by the EGR valve position correction coefficient to obtain the Lambda correction amount of the hydrogen injection part; The rail pressure Lambda correction module obtains the rail pressure Lambda correction by the following steps: The speed and hydrogen flow of the hydrogen engine are calibrated through Map to obtain the Lambda correction value of the hydrogen injection part; After the rail pressure is converted into Curve, it is multiplied by the Lambda correction value of the hydrogen injection part to obtain the Lambda correction value of the rail pressure part; The closed-loop correction unit includes an oxygen sensor range monitoring module and a correction value control module, wherein: The oxygen sensor range monitoring module includes: The reasonable range detection submodule is used to determine whether the oxygen sensor raw voltage value exceeds a preset reasonable range after obtaining the oxygen sensor raw voltage value. If it exceeds, the closed-loop part Lambda correction amount is directly set to a predetermined calibration value. If it does not exceed, the oxygen sensor raw voltage value is output; The Lambda measurement value acquisition submodule is used to convert the original voltage value of the oxygen sensor output by the reasonable range detection submodule into the Lambda measurement value, and obtain the final Lambda measurement value of the oxygen sensor after PT1 filtering; The implementation of the correction value control module includes the following steps: Step 1: Preset a Lambda range based on the design value of the hydrogen engine's air-fuel ratio: If the Lambda measurement value obtained by the oxygen sensor range monitoring module is within the Lambda range, it is determined that the Lambda value is in the Normal state and the process goes to step 2; If the Lambda measurement value obtained by the oxygen sensor range monitoring module exceeds the Lambda range, proceed to step 3; Step 2: Set the closed-loop Lambda correction to 0; Step 3: In the first step, the closed-loop Lambda correction value is stepped to the scalable value LamdaPosStep_C, and then gradually ramped until the closed-loop Lambda correction value reaches the upper limit of the closed-loop correction value. Each time the closed-loop Lambda correction value is updated, the closed-loop Lambda correction value is output.