A method and system for improving intake uniformity of each cylinder of an engine

Abstract

The application relates to a method and system for improving the consistency of intake air of each cylinder of an engine, obtaining the corresponding crankshaft tooth rotation speed of each cylinder of the engine, calculating the average rotation speed of the crankshaft tooth in a set time period as the average rotation speed corresponding to each cylinder, determining the difference between the average rotation speed of each cylinder and a set target rotation speed; when the absolute value of the difference in rotation speed is not less than a preset value and the gear of the whole vehicle is not in neutral, a correction base value of the ignition advance angle of the corresponding cylinder is determined according to the obtained difference; a correction factor of the base correction value of the ignition advance angle is obtained through a gear signal, vehicle weight information and slope information through table lookup; 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 finally executed ignition advance angle.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vehicle control, in particular to a method and system for improving the consistency of engine intake of each cylinder. BACKGROUND

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

[0003] For natural gas, methanol and other clean fuel ignition type engines, 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, and cannot measure the real-time air-fuel ratio of each cylinder. Due to the influence of engine parts assembly, design or other reasons, the intake of each cylinder is uneven, which will cause the mixture of a certain cylinder to be too thick or too thin, so that the intake of the cylinder is inconsistent with other cylinders. The engine speed signal and the measurement result of the oxygen sensor are average values, and the mixture of each cylinder is adjusted to the thick or thin direction through closed loop control, and no matter which direction will lead to the working condition of a certain cylinder being worse, resulting in unstable engine speed and excessive fluctuation. If an oxygen sensor or a cylinder pressure sensor is added to each cylinder to monitor the combustion of each cylinder, the cost of the engine will increase. SUMMARY

[0004] In order to solve the technical problems existing in the background art, the present application provides a method and system for improving the consistency of engine intake of each cylinder, especially the control of idle speed, which realizes stable control of engine speed without increasing sensors and improves the reliability of the engine.

[0005] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0006] The first aspect of the present application provides a method for improving the consistency of engine intake of each cylinder, comprising the following steps:

[0007] Obtain the corresponding crankshaft tooth speed of each cylinder of the engine, calculate the average speed of the crankshaft tooth in the set time period as the average speed of 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 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 value;

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

[0010] The product of the correction base value and the correction factor is a 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] Further, when the absolute value of the difference in rotational speed is not less than a preset value and the vehicle gear is in neutral, a correction value of the ignition advance angle of the corresponding cylinder is obtained according to 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] Further, the obtained difference is used to obtain the correction value of the ignition advance angle of the corresponding cylinder through rotational speed PID closed-loop control or a preset data table.

[0013] Further, when the absolute value of the difference in rotational speed is less than a preset value, the ignition advance angles of the cylinders are not corrected.

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

[0015] Further, the rotational speed control mode at least includes a high-low idle speed control mode, an external rotational speed control mode, a full-range scheduling mode and a PTO mode.

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

[0017] Further, the correction factor of the ignition advance angle base correction value is obtained by querying a preset MAP according to the gear signal, the vehicle weight information and the slope information.

[0018] The second aspect of the present application provides a system for improving the intake consistency of each cylinder of an engine, comprising:

[0019] An information acquisition module is configured to obtain the crankshaft tooth rotational speed, the set target rotational speed, the gear signal, the vehicle weight information and the slope information corresponding to each cylinder of the engine.

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

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

[0022] The information processing module is further configured to obtain a correction factor of the basic correction value of the spark advance angle through the gear signal, the vehicle weight information and the slope information by table lookup.

[0023] The information processing module is further configured to multiply the basic value and the correction factor to obtain a final correction amount, and add the obtained final correction amount to the spark advance angle of the corresponding cylinder to obtain the finally executed spark advance angle.

[0024] Further, the information processing module is further configured to obtain the spark advance angle correction value of the corresponding cylinder according to the obtained difference value when the absolute value of the difference value of the rotation speed is not less than a preset value and the gear of the whole vehicle is in neutral, and obtain the finally executed spark advance angle by adding the correction value to the spark advance angle of the corresponding cylinder.

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

[0026] 1. The actual rotation speed of each cylinder is determined by the rotation speed of the crankshaft, the spark advance angle correction amount of each cylinder is obtained according to the difference value between the actual rotation speed and the target rotation speed of each cylinder, the influence of the gear of the whole vehicle, the vehicle weight and the slope on the rotation speed control is considered, the further correction condition is determined, and the rotation speed fluctuation problem caused by the inconsistent intake of different cylinders is solved by the corrected spark advance angle during the rotation speed control.

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

[0028] The drawings accompanying the specification of this application form a part thereof, serve to provide further understanding of the application, and together with the description of the exemplary embodiments of the application, serve to explain the application, and do not constitute improper limitations on the application.

[0029] Figure 1 is a flowchart provided by one or more embodiments of the application to improve the consistency of the intake of each cylinder. DETAILED DESCRIPTION

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

[0031] It should be pointed out that the following detailed description is exemplary and is intended to provide further explanation of the application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as generally understood by those skilled in the art to which the application belongs.

[0032] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting, as the scope of the exemplary embodiments of this disclosure is intended to be only limited by the appended claims. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that the use of the terms "comprise", "include", "contain" and / or "have" in this specification, particularly in the claims, is taken to mean the presence of a stated feature, step, operation, device, component and / or combination, but not to the exclusion in all cases of one or more additional features, steps, operations, devices, components and / or combinations.

[0033] As introduced in the background, when the clean fuel spark ignition engine uses the air-fuel ratio closed loop control based on the 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 cannot obtain the real-time air-fuel ratio of each cylinder. When the intake air of each cylinder is uneven, the mixture of a certain cylinder will be too rich or too lean, and the intake air of the cylinder will be 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, and the average value and the speed signal can only adjust the mixture of each cylinder as a whole to be rich or lean, which will cause the working condition of a certain cylinder to be worse, resulting in unstable engine speed and excessive fluctuation. If an oxygen sensor or a cylinder pressure sensor is added to each cylinder to monitor the combustion of each cylinder, the cost of the engine will increase.

[0034] Therefore, the following embodiments give a method and system for improving the consistency of the intake air of each cylinder of the engine, using the crankshaft tooth speed to determine the actual speed of each cylinder, and using the difference between the actual speed of each cylinder and the target speed to obtain the ignition advance angle correction value of each cylinder through closed loop control, or directly using the difference between the actual speed of each cylinder and the target speed to obtain the ignition advance angle correction value of each cylinder by looking up a preset data table, while considering the influence of the gear, vehicle weight and slope on the speed control to determine the further correction, and solving the speed fluctuation problem caused by the inconsistent intake air of different cylinders through the corrected ignition advance angle.

[0035] Embodiment one:

[0036] The prior art generally improves the idle speed stability problem caused by the inconsistent intake air of each cylinder through speed closed loop and air-fuel ratio closed loop. The present embodiment identifies the speed of each cylinder by the cylinder number calculated by the ECU and the corresponding crankshaft tooth speed, and obtains the ignition advance angle correction value of each cylinder through closed loop control according to the difference between the actual average speed of each cylinder and the target speed, or directly obtains the ignition advance angle correction value of each cylinder by looking up a preset data table, which solves the speed fluctuation problem caused by the inconsistent intake air of different cylinders to a certain extent, while considering the influence of the vehicle load on the idle speed, and calculating when the engine is in gear and neutral, and introducing the influence of the gear, vehicle weight and slope on the speed control.

[0037] Obtaining the corresponding crankshaft tooth speed of each cylinder of the engine, calculating the average speed of the crankshaft tooth in the set time period as the average speed corresponding to each cylinder, and determining 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 vehicle gear is not in neutral, a correction base value of the ignition advance angle of the corresponding cylinder is determined according to the obtained difference; a correction factor of the base correction value of the ignition advance angle is obtained by looking up a table according to the gear signal, the vehicle weight information and the slope information; the product of the correction base value and the correction factor is the final correction amount, and the final correction amount is added to the ignition advance angle of the corresponding cylinder to obtain the finally executed ignition advance angle;

[0039] When the absolute value of the speed difference is not less than the preset value and the vehicle gear is in neutral, a correction value of the ignition advance angle of the corresponding cylinder is obtained according to the obtained difference, and the finally executed 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, the ignition advance angle of each cylinder is not corrected.

[0041] The specific process is shown in Figure 1 .

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

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

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

[0045] Step 4, taking the average speed of the crankshaft tooth 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, step 6 is executed, if no, step 8 is executed; in this step, the ignition advance angle of each cylinder is corrected only when the actual speed and the set speed deviation is greater than a certain value, if the speed deviation is very small, the ignition advance angle is not corrected; wherein the preset value is a calibration value, which can be calibrated according to the actual application;

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

[0048] Step 7, the correction value is added to the ignition advance angle of the corresponding cylinder to obtain the final executed ignition advance angle;

[0049] Step 8, when the absolute value of the difference in the rotational speed is less than the preset value, the ignition advance angle of each cylinder is not corrected;

[0050] Meanwhile, when the absolute value of the difference in the rotational speed is greater than or equal to the preset value and the gear of the whole vehicle is not in neutral, it is indicated that the vehicle is running in gear at this time, and at this time, a correction factor of a basic correction value of the ignition advance angle is obtained by searching a preset MAP through the gear of the whole vehicle, the vehicle weight and the slope information; a basic correction value of the ignition advance angle of the corresponding cylinder is obtained according to the average value and the target value of each cylinder through rotational speed PID closed-loop control, or the basic correction value of the ignition advance angle of the corresponding cylinder is obtained by searching a preset data table through the difference value of each cylinder; the product of the basic correction value and the correction factor is the final correction amount, and the final correction amount obtained is added to the ignition advance angle of the corresponding cylinder to obtain the final executed ignition advance angle.

[0051] The above process determines the actual rotational speed of each cylinder by using the rotational speed of the crankshaft, obtains a correction amount of the ignition advance angle of each cylinder according to the actual rotational speed and the target rotational speed of each cylinder through closed-loop control, or obtains the correction amount of the ignition advance angle of each cylinder by searching a preset data table through the difference value of the actual rotational speed and the target rotational speed of each cylinder, simultaneously considers the influence of the gear, the vehicle weight and the slope of the whole vehicle in gear on the rotational speed control to determine further correction, and solves the rotational speed fluctuation problem in rotational speed control caused by inconsistent intake of different cylinders through the corrected ignition advance angle.

[0052] The whole process can solve the problem of unstable engine rotational speed control caused by inconsistent intake of each cylinder of the engine to a certain extent without additional sensors and actuators, and improves the reliability of the engine.

[0053] Embodiment two:

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

[0055] An information acquisition module for acquiring the corresponding rotational speed of the crankshaft, the set target rotational speed, the gear signal, the vehicle weight information and the slope information of each cylinder of the engine;

[0056] The information processing module is configured to: calculate the average rotation speed of the crankshaft in a set time period as the average rotation speed of each cylinder according to the rotation speed of the crankshaft corresponding to each cylinder, determine the difference between the average rotation speed of each cylinder and a set target rotation speed, when the absolute value of the difference in rotation speed is not less than a preset value and the gear of the whole vehicle is not in neutral, determine the correction base value of the ignition advance angle of the corresponding cylinder according to the obtained difference, obtain the correction factor of the base correction value of the ignition advance angle through the gear signal, the vehicle weight information and the slope information, and through table lookup, multiply the correction base value and the correction factor to obtain the final correction amount, and add the obtained final correction amount to the ignition advance angle of the corresponding cylinder to obtain the finally executed ignition advance angle.

[0057] The information processing module is further configured to: when the absolute value of the difference in rotation speed is not less than a preset value and the gear of the whole vehicle is in neutral, obtain the correction value of the ignition advance angle of the corresponding cylinder according to the obtained difference, and obtain the finally executed ignition advance angle by adding the correction value to the ignition advance angle of the corresponding cylinder.

[0058] The actual rotation speed of each cylinder is determined by using the rotation speed of the crankshaft, the correction amount of the ignition advance angle of each cylinder is obtained by closed-loop control according to the actual rotation speed and the target rotation speed of each cylinder, or the correction amount of the ignition advance angle of each cylinder is obtained by looking up a preset data table according to the difference between the actual rotation speed and the target rotation speed of each cylinder, the further correction is determined by considering the influence of the gear, the vehicle weight and the slope of the whole vehicle on the rotation speed control when the vehicle is in gear, and the rotation speed fluctuation problem in rotation speed control caused by the inconsistent intake of different cylinders is solved by the corrected ignition advance angle.

[0059] The whole process can solve the problem of unstable engine rotation speed control caused by the uneven intake of each cylinder of the engine to a certain extent without additional sensors and actuators, and improves the reliability of the engine.

[0060] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method of improving the intake uniformity of each cylinder of an engine, characterized by, The method comprises the following steps: Obtaining the crankshaft tooth speed corresponding to each cylinder of the engine, calculating the average crankshaft tooth speed in a set time period as the average speed corresponding to each cylinder, and determining 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 vehicle gear is not in neutral, the correction base value of the ignition advance angle of the corresponding cylinder is determined according to the obtained difference value; The correction factor of the ignition advance angle base correction value is obtained through the gear signal, the vehicle weight information and the slope information by table lookup; 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 finally executed ignition advance angle.

2. The method of claim 1 wherein, When the absolute value of the speed difference is not less than the 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 value, and the finally executed ignition advance angle is obtained by adding the correction value to the ignition advance angle of the corresponding cylinder.

3. The method of claim 2 wherein the step of adjusting the amount of air supplied to each cylinder of the engine is performed by adjusting the amount of air supplied to each cylinder of the engine by adjusting the position of the throttle valve in each cylinder of the engine. The obtained difference value is controlled by speed PID closed loop or preset data table to obtain the ignition advance angle correction value of the corresponding cylinder.

4. The method of claim 1 wherein the step of improving the uniformity of the intake charge to each cylinder of the engine comprises the step of: When the absolute value of the speed difference is less than the preset value, the ignition advance angle of each cylinder is not corrected.

5. The method of claim 1 wherein the step of improving the uniformity of the intake charge to each cylinder of the engine comprises the step of: In the set speed control mode, the crankshaft tooth speed corresponding to each cylinder of the engine, the target speed, the gear signal, the vehicle weight information and the slope information are obtained to improve the intake consistency of each cylinder.

6. A method of improving the uniformity of the intake charge to the cylinders of an engine as recited in claim 5 wherein, The speed control mode at least includes high-low idle speed control mode, external speed control mode, full-range scheduling mode and PTO mode.

7. The method of claim 1 wherein the step of improving the uniformity of the intake charge to each cylinder of the engine comprises the step of: When the absolute value of the speed difference is not less than the preset value and the vehicle gear is not in neutral, the correction base value of the ignition advance angle of the corresponding cylinder is obtained by speed PID closed loop control or preset data table.

8. The method of claim 1 wherein the step of improving the uniformity of the intake charge to each cylinder of the engine comprises the step of: The correction factor of the ignition advance angle base correction value is obtained by querying the preset MAP through the gear signal, the vehicle weight information and the slope information.

9. A system for improving the uniformity of intake air to each cylinder of an engine, the system comprising: It comprises: An information acquisition module is configured to obtain the crankshaft tooth speed corresponding to each cylinder of the engine, the set target speed, the gear signal, the vehicle weight information and the slope information; An information processing module is configured to calculate the average crankshaft tooth speed in a set time period as the average speed corresponding to each cylinder according to the crankshaft tooth speed corresponding to each cylinder of the engine, 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 the correction base value of the ignition advance angle of the corresponding cylinder according to the obtained difference value when the absolute value of the speed difference is not less than the preset value and the vehicle gear is not in neutral; The information processing module is further configured to obtain the correction factor of the ignition advance angle base correction value by table lookup through the gear signal, the vehicle weight information and the slope information; The information processing module is further configured to obtain the finally executed ignition advance angle by adding the obtained final correction amount to the ignition advance angle of the corresponding cylinder.

10. A system for improving the uniformity of the intake charge to the cylinders of an engine as recited in claim 9, characterized in that, The information processing module is further configured to: when the absolute value of the difference in rotational speed is not less than a preset value and the gear of the whole vehicle is in neutral, obtaining a correction value of the ignition advance angle of the corresponding cylinder according to the obtained difference; and obtaining a final executed ignition advance angle by adding the correction value to the ignition advance angle of the corresponding cylinder.

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