Control method for improving no-load stability of engine

Abstract

The invention discloses a control method for improving no-load stability of an engine, which belongs to the technical field of engines, and comprises the following steps: detecting a starting success state, a rotating speed and an environment temperature of the engine, and when a sensor fault is detected, a temperature parameter monitored by the fault sensor is not used as a judgment item for judging whether a cylinder breaking operation mode is started or not; the temperature parameter monitored by the normal sensor is continuously used as an item for judging whether the cylinder breaking operation mode is started or not; after the engine is started successfully and time t1 is delayed, if the rotating speed n of the engine is larger than or equal to n1 and smaller than or equal to n2, and the environment temperature is not higher than a set temperature threshold value, the engine enters a cylinder breaking operation mode, and oil injection to an engine cylinder is stopped in turn according to the ignition sequence of the engine; when the engine meets the normal operation requirement condition, the engine stops the cylinder cut-off operation mode, the problems of white smoke emission and traveling block caused by unstable combustion when the engine is in no-load operation in the low-temperature environment are solved, and the reliability and the dynamic responsiveness of the engine are also guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical field of engines, and particularly relates to a control method for improving the no-load stability of an engine. Background Art

[0002] When the ambient temperature is relatively low and the engine starts and runs no-load for the first time, the overall temperature of the engine is relatively low, less working medium enters the cylinder, and due to the difference in component consistency, when some cylinders reach the end of the compression stroke, the temperature of the fuel-air mixture working medium in the cylinder is too low to be ignited by compression. The unburned mixture in the cylinder will be discharged during the exhaust stroke, resulting in the phenomena of white smoke emission and hunting.

[0003] The patent with publication number CN 117249011A in the prior art discloses a control method, which is to identify the rotational speed volatility of the idle running condition to determine hunting, and solve this problem by actively stopping fuel injection of one cylinder or multiple cylinders to make them stop working and increasing the circulating fuel quantity of the remaining cylinders. However, continuous fuel injection stop of one cylinder or multiple cylinders will cause a change in the torsional vibration mode of the crankshaft. In the long run, it will lead to abnormal wear of components such as the main bearing, connecting rod bearing, and thrust bearing, reducing reliability. At the same time, when the engine needs to quickly output power, due to the stop of fuel injection of one cylinder or multiple cylinders, the power response of the engine will become poor. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: aiming at the deficiencies in the prior art, to provide a control method for improving the no-load stability of an engine, which solves the problems of white smoke emission and hunting caused by unstable combustion during the no-load operation of the engine in a low-temperature environment, and also ensures the reliability and power response of the engine.

[0005] To solve the above technical problem, the technical solution of the present invention is:

[0006] A control method for improving the no-load stability of an engine includes the following steps:

[0007] Detect the successful start state of the engine, and detect the rotational speed and ambient temperature of the engine through sensors, where the ambient temperature includes two or more temperature parameters;

[0008] Detect whether all the sensors are faulty. When a faulty sensor is detected, the temperature parameter monitored by the faulty sensor is not used as a determination item for enabling or disabling the cylinder cut-off operation mode, and the temperature parameters monitored by the normal sensors continue to be used as determination items for enabling or disabling the cylinder cut-off operation mode;

[0009] When the engine starts successfully and after a delay time t1, if the rotational speed of the engine is not lower than a set first threshold and not higher than a second threshold, and the ambient temperature is not higher than a set temperature threshold, the engine enters the cylinder cut-off operation mode;

[0010] When the engine meets the conditions for normal operation requirements, the engine ends the cylinder deactivation operation mode and resumes normal operation;

[0011] The cylinder deactivation operation mode is to stop fuel injection into the engine cylinders in turn according to the firing order of the engine, and the number of cylinders with injection stopped and the rotation order are calibrated on the test bench.

[0012] Further, the ambient temperature includes at least two temperature parameters among the engine oil temperature, the coolant water temperature, the fuel temperature, and the temperature of the air after the intercooler.

[0013] Further, when the rotational speed of the engine exceeds the second threshold, the engine ends the cylinder deactivation operation mode and resumes normal operation.

[0014] Further, when the cylinder deactivation operation time of the engine exceeds t2, the engine ends the cylinder deactivation operation mode and resumes normal operation.

[0015] Further, when the rotational speed fluctuation rate of the engine within a period of time t3 exceeds the fluctuation rate threshold, the engine ends the cylinder deactivation operation mode and resumes normal operation.

[0016] Further, the calculation formula for the rotational speed fluctuation rate of the engine is:

[0017]

[0018] In the formula, C is the rotational speed fluctuation rate of the engine within a period of time t3;

[0019] n max is the highest rotational speed of the engine within a period of time t3;

[0020] n min is the lowest rotational speed of the engine within a period of time t3;

[0021] n 目标 is the target rotational speed of the engine.

[0022] Further, when the difference between the target rotational speed and the actual rotational speed of the engine is greater than the set third threshold and the cyclic fuel quantity is greater than the sum of the average value within a period of time t4 and the fuel quantity threshold, the engine ends the cylinder deactivation operation mode and resumes normal operation.

[0023] Further, when the override state is activated, the engine ends the cylinder deactivation operation mode and resumes normal operation.

[0024] Further, detect the original signal of the sensor, and when the original signal is abnormal, determine that the sensor is faulty.

[0025] Further, after the original signal of the faulty sensor becomes normal, the detection parameters of the sensor continue to be used as the determination item for whether to enable the cylinder cutoff operation mode.

[0026] After adopting the above technical solution, the beneficial effects of the present invention are as follows:

[0027] In the control method for improving the no-load stability of the engine disclosed by the present invention, based on the environmental state, through bench calibration verification, the fuel injection is stopped and the cylinders are cut off alternately in the most reliable way, avoiding the abnormal wear problem caused by long-term fuel injection stop of one cylinder or multiple cylinders, and ensuring reliability; when the engine is in the state of alternately stopping fuel injection and cutting off cylinders, since the number of working cylinders decreases, the work required for each cylinder increases, and the fuel injection amount increases, it is easier to ensure stable compression ignition in a low-temperature environment, ensuring the smooth operation of the engine and avoiding white smoke; when the normal operation requirement conditions are met, the engine ends the cylinder cutoff operation mode and resumes normal operation, ensuring the power response of the engine and meeting the normal power usage requirements of users. Description of the Drawings

[0028] Figure 1 It is a schematic flow chart of the control method for improving the no-load stability of the engine of the present invention. Detailed Embodiments

[0029] The following further describes the present invention in conjunction with the drawings and embodiments. The preferred embodiments of the present invention are shown in the drawings. The function of the drawings is to supplement the description of the text part of the specification, enabling people to intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it cannot be understood as a limitation on the protection scope of the present invention.

[0030] It should be noted that in the description of this specification, greater than, less than, exceeding, etc. are understood as not including the number itself, and above, below, within, etc. are understood as including the number itself. The terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features.

[0031] As Figure 1 shown, a control method for improving the no-load stability of an engine includes the following steps:

[0032] S10. Detect the successful start state of the engine, and detect the engine speed n and the ambient temperature through sensors. The ambient temperature includes more than two temperature parameters.

[0033] Among them, the ambient temperature includes at least two temperature parameters of the engine oil temperature T1, the coolant water temperature T2, the fuel temperature T3, and the air temperature after the intercooler T4. In this application, it is preferred that the ambient temperature includes all the above temperature parameters.

[0034] S20. Detect whether all sensors are faulty. When a faulty sensor is detected, the temperature parameter monitored by the faulty sensor is not used as a determination item for enabling or disabling the cylinder cutoff operation mode, and the temperature parameters monitored by normal sensors continue to be used as determination items for enabling or disabling the cylinder cutoff operation mode.

[0035] Specifically, detect the original signal of the sensor. When the original signal is abnormal, it is determined that the sensor is faulty. The original signal can be a voltage and / or current signal.

[0036] S21. After the original signal of the faulty sensor becomes normal, the detection parameters of this sensor continue to be used as determination items for enabling or disabling the cylinder cutoff operation mode.

[0037] S30. When the engine starts successfully and after a delay time t1, if the engine speed n is not lower than the set first threshold n1 and not higher than the second threshold n2, and the ambient temperature is not higher than the set temperature threshold, the engine enters the cylinder cutoff operation mode. That is, when the engine starts successfully and after a delay time t1, when the engine speed satisfies n1 ≤ n ≤ n2, and at the same time T1 ≤ T1’ or T2 ≤ T2’ or T3 ≤ T3’ or T4 ≤ T4’, the engine enters the cylinder cutoff operation mode.

[0038] Among them, the cylinder cutoff operation mode is to stop fuel injection into the engine cylinders in turn according to the engine firing order. The cylinders with fuel injection stopped can be one or multiple. In practical applications, the number of cylinders with fuel injection stopped and the rotation order are calibrated on the test bench.

[0039] S40. When the engine meets the normal operation requirement conditions, the engine ends the cylinder cutoff operation mode and resumes normal operation to ensure the power response of the engine.

[0040] In this application, there are multiple normal operation requirement conditions for the engine. As long as one of them is met, the cylinder cutoff operation mode ends. The following steps S41 to S45 describe each condition respectively.

[0041] S41. When the engine speed n exceeds the second threshold n2, that is, n > n2, the engine ends the cylinder cutoff operation mode and resumes normal operation.

[0042] When the engine speed increases to n2, the engine's cyclic fuel injection volume also increases accordingly. At this time, stable compression ignition can be achieved, eliminating the influence of the low-temperature environment on combustion stability. Therefore, the engine can end the cylinder cutoff operation mode.

[0043] S42. When the engine's cylinder cutoff operation time exceeds t2, the engine ends the cylinder cutoff operation mode and resumes normal operation.

[0044] As the time of intermittent cylinder shutdown and operation increases, the heat transfer of the working medium in the cylinder will cause the overall temperature of the engine and its coolant to rise. Each cylinder gradually achieves stable compression ignition, eliminating the influence of low-temperature environment on combustion stability. Therefore, when the engine cylinder shutdown operation time t > t2, the engine can end the cylinder shutdown operation mode.

[0045] S43. When the engine speed fluctuation rate within a period of time t3 exceeds the fluctuation rate threshold C1, the engine ends the cylinder shutdown operation mode and resumes normal operation. In this application, the engine only refers to the main engine, and the fluctuation rate threshold C1 is calibrated through a test bench.

[0046] Specifically, the calculation formula for the engine speed fluctuation rate is:

[0047]

[0048] In the formula, C is the engine speed fluctuation rate within a period of time t3;

[0049] n max is the maximum engine speed within a period of time t3;

[0050] n min is the minimum engine speed within a period of time t3;

[0051] n 目标 is the target engine speed.

[0052] When the engine has a greater speed demand, that is, when accelerating in the no-load state, the engine speed fluctuation rate increases. At this time, the engine ends the cylinder shutdown operation mode and resumes normal operation, ensuring the power response of the engine.

[0053] S44. When the difference between the target engine speed and the actual engine speed is greater than the set third threshold n3 and the circulating fuel quantity is greater than the sum of the average value within a period of time t4 and the fuel quantity threshold C2, that is, n 目标 - n > n3 and the circulating fuel quantity > the average value within time t4 + C2, the engine ends the cylinder shutdown operation mode and resumes normal operation.

[0054] When the engine has a greater speed and torque demand, the engine target speed n 目标 increases and the circulating fuel quantity increases. The increase in the engine circulating fuel injection quantity can also achieve stable compression ignition, eliminating the influence of low-temperature environment on combustion stability. Therefore, the engine can end the cylinder shutdown operation mode and resume normal operation.

[0055] Among them, the fuel quantity threshold C2 is the fuel quantity corresponding to the maximum load that the current fuel injection cylinder can bear.

[0056] S45. When the override state is activated, the engine ends the cylinder shutdown operation mode and resumes normal operation.

[0057] When there are special user requirements, the override switch can be used to end the alternate fuel injection cut-off cylinder operation state at any time and resume normal operation to ensure controllability at any time.

[0058] S50. After the alternate fuel injection cut-off cylinder strategy ends, record the number of cylinder cut-offs and the operation time for this time, which are used by developers to track and analyze the operation state of the strategy and optimize various thresholds.

[0059] S60. After the engine control system is powered off and stops running, the next start-up will re-detect from the above step S10 to determine whether to enter the cylinder cut-off operation mode.

[0060] The control method for improving the no-load stability of the engine according to the present invention alternately cuts off fuel injection to cylinders in the most favorable and reliable manner through bench calibration verification based on the engine speed and environmental conditions, solving the problems of white smoke emission and hunting caused by unstable combustion during the no-load operation of the engine in a low-temperature environment, and also ensuring the reliability of the engine. When the conditions for normal operation requirements are met, the engine ends the cylinder cut-off operation mode and resumes normal operation, ensuring the power response of the engine and meeting the normal power usage requirements of users.

[0061] Although the specific implementation manners of the present invention have been described above, those skilled in the art should understand that the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. These are only illustrative examples, and the protection scope of the present invention is defined by the claims. Without departing from the principles and essence of the present invention and without any creative work, those skilled in the art can make various changes or modifications to these implementation manners, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A control method for improving the no-load stability of an engine, characterized in that, It includes the following steps: Detect the successful start state of the engine, and detect the engine speed and ambient temperature through sensors. The ambient temperature includes more than two temperature parameters; Detect whether all the sensors are faulty. When a sensor fault is detected, the temperature parameter monitored by the faulty sensor is not used as a determination item for enabling or disabling the cylinder deactivation operation mode, and the temperature parameters monitored by the normal sensors continue to be used as determination items for enabling or disabling the cylinder deactivation operation mode; When the engine starts successfully and after a delay time t1, if the engine speed is not lower than the set first threshold and not higher than the second threshold, and the ambient temperature is not higher than the set temperature threshold, the engine enters the cylinder deactivation operation mode; When the engine meets the normal operation requirement conditions, the engine ends the cylinder deactivation operation mode and resumes normal operation; The cylinder deactivation operation mode is to stop fuel injection into the engine cylinders in turn according to the engine firing order. The number of cylinders to stop injection and the rotation order are calibrated on the test bench.

2. The control method for improving the no-load stability of the engine according to claim 1, characterized in that The ambient temperature includes at least two temperature parameters among oil temperature, coolant temperature, fuel temperature, and post-intercooler air temperature.

3. The control method for improving the no-load stability of an engine according to claim 1, characterized in that, When the engine speed exceeds the second threshold, the engine ends the cylinder deactivation operation mode and resumes normal operation.

4. The control method for improving the no-load stability of the engine according to claim 1, wherein When the cylinder deactivation operation time of the engine exceeds t2, the engine ends the cylinder deactivation operation mode and resumes normal operation.

5. The control method for improving the no-load stability of an engine according to claim 1, wherein When the engine speed volatility within a period of time t3 exceeds the volatility threshold, the engine ends the cylinder deactivation operation mode and resumes normal operation.

6. The control method for improving the no-load stability of the engine according to claim 4, characterized in that The calculation formula for the engine speed volatility is: In the formula, C is the engine speed volatility within a period of time t3; n max is the maximum rotational speed of the engine within a period of time t3; n min is the lowest rotational speed of the engine during a period of time t3; n 目标 is the target speed of the engine.

7. The control method for improving the no-load stability of the engine according to claim 1, characterized in that, When the difference between the target speed and the actual speed of the engine is greater than the set third threshold and the cyclic fuel quantity is greater than the sum of the average value within a period of time t4 and the fuel quantity threshold, the engine ends the cylinder deactivation operation mode and resumes normal operation.

8. The control method for improving the no-load stability of an engine according to claim 1, characterized in that, When the override state is activated, the engine ends the cylinder deactivation operation mode and resumes normal operation.

9. The control method for improving the no-load stability of an engine according to any one of claims 1 to 8, characterized in that, Detect the original signals of the sensors. When the original signals are abnormal, it is determined that the sensors are faulty.

10. The control method for improving the no-load stability of the engine according to claim 9, characterized in that, When the original signals of the faulty sensors become normal, the detection parameters of the sensors continue to be used as determination items for enabling or disabling the cylinder deactivation operation mode.

Images