Method and system for improving air inlet consistency of cylinders of engine

Abstract

The invention relates to a method and system for improving air inlet consistency of all cylinders of an engine, and the method comprises the steps: obtaining the crankshaft tooth rotation speed corresponding to all the cylinders of the engine, calculating the average crankshaft tooth rotation speed in a set time period as the average rotation speed corresponding to all the cylinders, and determining the difference value between the average rotation speed of all the cylinders and the set target rotation speed; when the absolute value of the difference value of the rotating speeds is not smaller than a preset value and the gear of the whole vehicle is not in a neutral gear, determining a corrected basic value of an ignition advance angle of a corresponding cylinder according to the obtained difference value; a correction factor of the basic correction value of the ignition advance angle is obtained through table look-up according to the gear signal, the vehicle weight information and the slope information; the product of the correction basic value and the correction factor is the final correction amount, and the obtained final correction amount is accumulated to the ignition advance angle of the corresponding cylinder to obtain the final execution ignition advance angle.

Description

Technical Field

[0001] The present invention relates to the field of vehicle control technology, and in particular to a method and a system for improving the consistency of air intake in each cylinder of an engine. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] For clean fuel spark-ignition engines such as natural gas and methanol, in addition to the conventional speed PID closed-loop control, there is also an air-fuel ratio closed-loop control method based on the oxygen sensor signal. Among them, the oxygen sensor is generally installed on the exhaust manifold and can only measure the average value of the air-fuel ratio, but cannot measure the real-time air-fuel ratio of each cylinder. Affected by the assembly, design or other reasons of the engine parts, when the intake of each cylinder is uneven, the mixture of a cylinder will be too rich or too lean, making the intake volume of this cylinder inconsistent with that of other cylinders. The engine speed signal and the result measured by the oxygen sensor are the average value. Through closed-loop control, the mixture of each cylinder is adjusted in the direction of rich or lean. No matter which direction it is, it will cause the working condition of a certain cylinder to be worse, resulting in unstable engine speed and excessive fluctuations. If an oxygen sensor or cylinder pressure sensor is added to each cylinder to monitor the combustion conditions of each cylinder, the engine cost will increase. Summary of the invention

[0004] In order to solve the technical problems existing in the above-mentioned background technology, the present invention provides a method and system for improving the consistency of intake air in each cylinder of an engine, especially the control of idle speed, so as to achieve stable control of engine speed without adding sensors and improve the reliability of the engine.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A first aspect of the present invention provides a method for improving the consistency of air intake in each cylinder of an engine, comprising the following steps:

[0007] Obtain the crankshaft tooth speed corresponding to each cylinder of the engine, calculate the average crankshaft tooth speed within a set time period as the average speed corresponding to each cylinder, and determine the difference between the average speed of each cylinder and the set target speed;

[0008] When the absolute value of the speed difference is not less than the preset value and the gear position of the vehicle is not in neutral, the correction basic value of the ignition advance angle of the corresponding cylinder is determined according to the obtained difference;

[0009] The correction factor of the basic correction value of the ignition advance angle is obtained by looking up the table through the gear position signal, vehicle weight information and slope information;

[0010] The product of the correction base value and the correction factor is the final correction amount, and the obtained "final correction amount" is added to the ignition advance angle of the corresponding cylinder to obtain the final executed ignition advance angle.

[0011] Furthermore, when the absolute value of the speed difference is not less than a preset value and the vehicle gear is in neutral, an ignition advance angle correction value of the corresponding cylinder is obtained based on the obtained difference, and the final executed ignition advance angle is obtained by adding the correction value to the ignition advance angle of the corresponding cylinder.

[0012] Furthermore, the obtained difference is controlled by a speed PID closed loop or a preset data table to obtain an ignition advance angle correction value of the corresponding cylinder.

[0013] Furthermore, when the absolute value of the speed difference is less than a preset value, the ignition advance angle of each cylinder is not corrected.

[0014] Furthermore, under the set speed control mode, the crankshaft tooth speed, target speed, gear signal, vehicle weight information and slope information corresponding to each cylinder of the engine are obtained to improve the intake consistency of each cylinder.

[0015] Furthermore, the speed control mode includes at least high and low idle speed control modes, external speed control mode, full-range scheduling mode and PTO mode.

[0016] Furthermore, when the absolute value of the speed difference is not less than a preset value and the vehicle gear is not in neutral, the obtained difference is obtained through speed PID closed-loop control or a preset data table to obtain a corrected basic value of the ignition advance angle of the corresponding cylinder.

[0017] Furthermore, the correction factor of the basic correction value of the ignition advance angle is obtained by querying the preset MAP through the gear signal, vehicle weight information and slope information.

[0018] A second aspect of the present invention provides a system for improving the consistency of air intake in each cylinder of an engine, comprising:

[0019] An information acquisition module is used to obtain the crankshaft gear speed corresponding to each cylinder of the engine, the set target speed, the gear position signal, the vehicle weight information and the slope information;

[0020] The information processing module is configured to: calculate the average crankshaft tooth speed within a set time period according to the crankshaft tooth speed corresponding to each cylinder of the engine, as the average speed corresponding to each cylinder, and determine the difference between the average speed of each cylinder and the set target speed;

[0021] The information processing module is further configured to: determine a correction base value of the ignition advance angle of the corresponding cylinder according to the obtained difference when the absolute value of the speed difference is not less than a preset value and the gear position of the vehicle is not in neutral;

[0022] The information processing module is further configured to: obtain a correction factor of a basic correction value of an ignition advance angle by looking up a table through the gear position signal, the vehicle weight information and the slope information;

[0023] The information processing module is further configured to: multiply the product of the correction base value and the correction factor as the final correction amount, and add the obtained "final correction amount" to the ignition advance angle of the corresponding cylinder to obtain the final executed ignition advance angle.

[0024] Furthermore, the information processing module is also configured as follows: when the absolute value of the speed difference is not less than a preset value and the vehicle gear is in neutral, an ignition advance angle correction value of the corresponding cylinder is obtained based on the obtained difference, and the final executed ignition advance angle is obtained by adding the correction value to the ignition advance angle of the corresponding cylinder.

[0025] Compared with the prior art, one or more of the above technical solutions have the following beneficial effects:

[0026] 1. The actual speed of each cylinder is determined by the crankshaft tooth speed. The ignition advance angle correction of each cylinder is obtained according to the difference between the actual speed of each cylinder and the target speed. At the same time, the influence of the gear position, vehicle weight and slope on the speed control when the vehicle is in gear is considered to determine further corrections. The corrected ignition advance angle can solve the speed fluctuation problem caused by inconsistent intake of different cylinders during speed control.

[0027] 2. The whole process does not require additional sensors and actuators. The existing sensors can be used to solve the problem of unstable engine speed control caused by uneven air intake in each cylinder to a certain extent, thereby improving the reliability of the engine in a low-cost manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0029] Figure 1 It is a schematic diagram of a flow chart for improving the consistency of air intake in each cylinder provided by one or more embodiments of the present invention. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0031] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0032] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0033] As introduced in the background technology, when a clean fuel ignition engine uses an air-fuel ratio closed-loop speed control based on an oxygen sensor signal, the oxygen sensor is generally installed on the exhaust manifold to measure the average value of the air-fuel ratio of each cylinder, and the real-time air-fuel ratio of each cylinder cannot be obtained. When the intake of each cylinder is uneven, the mixture of a certain cylinder will be too rich or too lean, making the intake volume of this cylinder inconsistent with that of other cylinders. The oxygen sensor installed on the exhaust manifold can only measure the average value of the air-fuel ratio of each cylinder. Using this average value and the speed signal, the mixture of each cylinder can only be adjusted to be rich or lean as a whole, which will cause the working condition of a certain cylinder to be worse, resulting in unstable engine speed and excessive fluctuations. If an oxygen sensor or cylinder pressure sensor is added to each cylinder to monitor the combustion conditions of each cylinder, the cost of the engine will increase.

[0034] Therefore, the following embodiment provides a method and system for improving the intake consistency of each cylinder of an engine, using the crankshaft tooth speed to determine the actual speed corresponding to each cylinder, and performing closed-loop control based on the actual speed of each cylinder and the target speed to obtain the ignition advance angle correction amount of each cylinder, or using the difference between the actual speed of each cylinder and the target speed to check the preset data table to obtain the ignition advance angle correction amount of each cylinder, while considering the influence of the gear position, vehicle weight and slope on the speed control when the whole vehicle is in gear, determining further correction conditions, and solving the speed fluctuation problem during speed control caused by inconsistent intake of different cylinders through the corrected ignition advance angle.

[0035] Embodiment 1:

[0036] The prior art generally improves the idle speed stability problem caused by inconsistent intake of each cylinder by speed closed loop and air-fuel ratio closed loop. This embodiment identifies the speed corresponding to each cylinder by the cylinder number of each cylinder calculated by the ECU and the crankshaft tooth speed corresponding to the cylinder number, and performs closed loop control according to the actual average speed of each cylinder and the target speed to obtain the ignition advance angle correction value of each cylinder, or directly uses the difference between the actual speed of each cylinder and the target speed to check the preset data table to obtain the ignition advance angle correction value of each cylinder, thereby solving the speed fluctuation problem caused by inconsistent intake of different cylinders to a certain extent, and considering the influence of the vehicle load on the idle speed, respectively calculate when the engine is in gear and neutral, and introduce the influence of gear position, vehicle weight and slope on speed control.

[0037] Obtain the crankshaft tooth speed corresponding to each cylinder of the engine, calculate the average crankshaft tooth speed within a set time period as the average speed corresponding to each cylinder, and determine the difference between the average speed of each cylinder and the set target speed;

[0038] When the absolute value of the speed difference is not less than the preset value and the gear position of the vehicle is not in neutral, the correction base value of the ignition advance angle of the corresponding cylinder is determined according to the obtained difference; the correction factor of the basic correction value of the ignition advance angle is obtained by looking up the table through the gear signal, vehicle weight information and slope information; the product of the correction base value and the correction factor is the final correction amount, and the obtained "final correction amount" is accumulated to the ignition advance angle of the corresponding cylinder to obtain the final executed ignition advance angle;

[0039] When the absolute value of the speed difference is not less than a preset value and the vehicle gear is in neutral, the ignition advance angle correction value of the corresponding cylinder is obtained according to the obtained difference, and the final ignition advance angle is obtained by adding the correction value to the ignition advance angle of the corresponding cylinder;

[0040] When the absolute value of the speed difference is less than the preset value, no correction is made to the ignition advance angle of each cylinder.

[0041] The specific process is as follows Figure 1 shown.

[0042] Step 1, obtaining parameters such as engine speed, speed control mode, target speed of speed control, gear signal, vehicle weight, slope, engine cylinder number calculated by ECU, speed of each crankshaft tooth, etc.; wherein the speed control mode includes normal high and low idle speed control of the engine, external speed control, full-range scheduling, and PTO modes;

[0043] Step 2, determine whether the current working condition of the engine is the speed control mode; if the preset condition is met, execute step 3, otherwise re-execute step 1 and wait for the next step of judgment;

[0044] Step 3, calculating the average speed of the crankshaft teeth corresponding to each cylinder;

[0045] Step 4, taking the average speed of the crankshaft teeth of each cylinder as the average speed corresponding to each cylinder, and calculating the difference between the average speed of each cylinder and the set target speed;

[0046] Step 5, judging whether the absolute value of the difference is greater than or equal to the preset value, and the vehicle gear is in neutral, if yes, executing step 6, if not, executing step 8; in this step, the ignition advance angle of each cylinder is corrected only when the deviation between the actual speed and the set speed is greater than a certain value, and the ignition advance angle is not corrected if the speed deviation is very small; wherein the preset value is the calibration value, and the specific data can be calibrated according to the actual application;

[0047] Step 6: When the absolute value of the speed difference is greater than or equal to the preset value and the vehicle gear is in neutral, the speed PID closed-loop control is performed according to the average value of each cylinder and the target value to obtain the ignition advance angle correction value of the corresponding cylinder, or the ignition advance angle correction value of the corresponding cylinder is obtained by looking up the preset data table through the difference of each cylinder;

[0048] Step 7: Add the correction value to the ignition advance angle of the corresponding cylinder to obtain the final ignition advance angle;

[0049] Step 8: When the absolute value of the speed difference is less than a preset value, no correction is made to the ignition advance angle of each cylinder;

[0050] At the same time, when the absolute value of the speed difference is greater than or equal to the preset value and the vehicle gear is not in neutral, it means that the vehicle is running in gear. At this time, it is necessary to query the preset MAP through information such as the vehicle gear, weight and slope to obtain the correction factor of the basic correction value of the ignition advance angle; perform speed PID closed-loop control according to the average value of each cylinder and the target value to obtain the corrected basic value of the ignition advance angle of the corresponding cylinder, or query the preset data table through the difference of each cylinder to obtain the corrected basic value of the ignition advance angle of the corresponding cylinder; the product of the corrected basic value and the correction factor is the final correction amount, and the obtained "final correction amount" is added to the ignition advance angle of the corresponding cylinder to obtain the final executed ignition advance angle.

[0051] The above process uses the crankshaft tooth speed to determine the actual speed corresponding to each cylinder, and performs closed-loop control based on the actual speed of each cylinder and the target speed to obtain the ignition advance angle correction amount of each cylinder, or uses the difference between the actual speed of each cylinder and the target speed to check the preset data table to obtain the ignition advance angle correction amount of each cylinder. At the same time, the influence of the gear position, vehicle weight and slope on the speed control when the whole vehicle is in gear is considered, and further correction conditions are determined. The speed fluctuation problem during speed control caused by inconsistent intake of different cylinders is solved through the corrected ignition advance angle.

[0052] The entire process does not require any additional sensors or actuators, and can to a certain extent solve the problem of unstable engine speed control caused by uneven air intake in each cylinder, thereby improving the reliability of the engine.

[0053] Embodiment 2:

[0054] A system for improving the consistency of air intake in each cylinder of an engine, comprising:

[0055] An information acquisition module is used to obtain the crankshaft gear speed corresponding to each cylinder of the engine, the set target speed, the gear position signal, the vehicle weight information and the slope information;

[0056] The information processing module is configured as follows: according to the crankshaft tooth speed corresponding to each cylinder of the engine, the average crankshaft tooth speed within a set time period is calculated as the average speed corresponding to each cylinder, and the difference between the average speed of each cylinder and the set target speed is determined; when the absolute value of the speed difference is not less than a preset value and the gear position of the whole vehicle is not in neutral, the correction base value of the ignition advance angle of the corresponding cylinder is determined according to the obtained difference; through the gear signal, vehicle weight information and slope information, the correction factor of the basic correction value of the ignition advance angle is obtained by looking up the table; the product of the correction base value and the correction factor is the final correction amount, and the obtained "final correction amount" is added to the ignition advance angle of the corresponding cylinder to obtain the final executed ignition advance angle.

[0057] The information processing module is also configured as follows: when the absolute value of the speed difference is not less than a preset value and the vehicle gear is in neutral, an ignition advance angle correction value of the corresponding cylinder is obtained based on the obtained difference, and the final executed ignition advance angle is obtained by adding the correction value to the ignition advance angle of the corresponding cylinder.

[0058] The actual speed of each cylinder is determined by the crankshaft tooth speed, and closed-loop control is performed based on the actual speed of each cylinder and the target speed to obtain the ignition advance angle correction amount of each cylinder. Alternatively, the difference between the actual speed of each cylinder and the target speed is used to check the preset data table to obtain the ignition advance angle correction amount of each cylinder. At the same time, the effects of the gear position, vehicle weight and slope on the speed control when the vehicle is in gear are considered to determine further corrections, and the speed fluctuation problem during speed control caused by inconsistent intake of different cylinders is solved through the corrected ignition advance angle.

[0059] The entire process does not require any additional sensors or actuators, and can to a certain extent solve the problem of unstable engine speed control caused by uneven air intake in each cylinder, thereby improving the reliability of the engine.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for improving the consistency of air intake in each cylinder of an engine, characterized in that: The following steps are involved: Obtain the crankshaft tooth speed corresponding to each cylinder of the engine, calculate the average crankshaft tooth speed within a set time period as the average speed corresponding to each cylinder, and determine the difference between the average speed of each cylinder and the set target speed; When the absolute value of the speed difference is not less than the preset value and the gear position of the vehicle is not in neutral, the correction basic value of the ignition advance angle of the corresponding cylinder is determined according to the obtained difference; The correction factor of the basic correction value of the ignition advance angle is obtained by looking up the table through the gear position signal, vehicle weight information and slope information; The product of the correction base value and the correction factor is the final correction amount. The obtained "final correction amount" is added to the ignition advance angle of the corresponding cylinder to obtain the final ignition advance angle.

2. A method for improving the consistency of air intake in each cylinder of an engine as claimed in claim 1, characterized in that: When the absolute value of the speed difference is not less than a preset value and the vehicle gear is in neutral, the ignition advance angle correction value of the corresponding cylinder is obtained according to the obtained difference, and the final ignition advance angle is obtained by adding the correction value to the ignition advance angle of the corresponding cylinder.

3. A method for improving the consistency of air intake in each cylinder of an engine as claimed in claim 2, characterized in that: The obtained difference is controlled by the speed PID closed loop or the preset data table to obtain the ignition advance angle correction value of the corresponding cylinder.

4. A method for improving the consistency of air intake in each cylinder of an engine as claimed in claim 1, characterized in that: When the absolute value of the speed difference is less than the preset value, no correction is made to the ignition advance angle of each cylinder.

5. A method for improving the consistency of air intake in each cylinder of an engine as claimed in claim 1, characterized in that: Under the set speed control mode, the crankshaft tooth speed, target speed, gear signal, vehicle weight information and slope information corresponding to each cylinder of the engine are obtained to improve the intake consistency of each cylinder.

6. A method for improving the consistency of air intake in each cylinder of an engine as claimed in claim 5, characterized in that: The speed control modes include at least high and low idle speed control modes, external speed control mode, full-range scheduling mode and PTO mode.

7. A method for improving the consistency of air intake in each cylinder of an engine as claimed in claim 1, characterized in that: When the absolute value of the speed difference is not less than the preset value and the vehicle gear is not in neutral, the obtained difference is obtained through the speed PID closed-loop control or the preset data table to obtain the corrected basic value of the ignition advance angle of the corresponding cylinder.

8. A method for improving the consistency of air intake in each cylinder of an engine as claimed in claim 1, characterized in that: The correction factor of the basic correction value of the ignition advance angle is obtained by querying the preset MAP through the gear signal, vehicle weight information and slope information.

9. A system for improving the consistency of air intake in each cylinder of an engine, characterized in that: include: An information acquisition module is used to obtain the crankshaft gear speed corresponding to each cylinder of the engine, the set target speed, the gear position signal, the vehicle weight information and the slope information; The information processing module is configured to: calculate the average crankshaft tooth speed within a set time period according to the crankshaft tooth speed corresponding to each cylinder of the engine, as the average speed corresponding to each cylinder, and determine the difference between the average speed of each cylinder and the set target speed; The information processing module is further configured to: determine a correction base value of the ignition advance angle of the corresponding cylinder according to the obtained difference when the absolute value of the speed difference is not less than a preset value and the gear position of the vehicle is not in neutral; The information processing module is further configured to: obtain a correction factor of a basic correction value of an ignition advance angle by looking up a table through the gear position signal, the vehicle weight information and the slope information; The information processing module is further configured to: multiply the product of the correction base value and the correction factor as the final correction amount, and add the obtained "final correction amount" to the ignition advance angle of the corresponding cylinder to obtain the final executed ignition advance angle.

10. A system for improving the consistency of air intake in each cylinder of an engine as claimed in claim 9, characterized in that: The information processing module is also configured as follows: when the absolute value of the speed difference is not less than a preset value and the vehicle gear is in neutral, an ignition advance angle correction value of the corresponding cylinder is obtained based on the obtained difference, and the final executed ignition advance angle is obtained by adding the correction value to the ignition advance angle of the corresponding cylinder.

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