A method for monitoring injection timing of a fuel system

Abstract

The present invention discloses a method for monitoring the injection timing of a fuel system, comprising calculating a single tooth cycle according to an engine speed, calculating the injection reference tooth number according to an injection-related signal and a single tooth cycle; calculating the time difference between the timestamp of the falling edge of the injection reference tooth and the injection interruption moment according to the injection reference tooth number, a single tooth cycle and an injection-related signal; calculating the number of teeth of the crankshaft tooth from the injection reference tooth to the injection top dead center of the current injection cylinder, calculating the actual injection timing according to the number of teeth of the crankshaft tooth from the injection reference tooth to the injection top dead center of the current injection cylinder, the injection angular velocity, the time difference between the falling edge of the injection reference tooth and the injection interruption, and the angle between two adjacent crankshaft teeth of the crankshaft disk; judging whether the actual injection timing is within a set injection threshold range and whether the difference between the actual injection timing and the set injection timing is within a set injection deviation threshold range. The present invention can accurately calculate the actual injection timing.

Description

Technical Field

[0001] The invention relates to the technical field of engine control, in particular to a method for monitoring the injection timing of a fuel system. Background Art

[0002] The injection timing of a diesel engine refers to the injection advance angle, which refers to the crankshaft angle of the piston from the top dead center when the injector starts to spray fuel. The size of the injection advance angle has a great influence on the operation of the diesel engine. When the injection advance angle is too large, it will lead to a longer pre-combustion period, causing the diesel engine to work roughly. When the injection advance angle is too small, the diesel combustion process will be delayed, the maximum pressure value will drop, and the thermal efficiency of the diesel engine will be significantly reduced. The correct calculation and execution of the injection advance angle is the premise for achieving efficient combustion of the diesel engine, and it is also the premise for ensuring the correct power output of the diesel engine. Only by ensuring the correct power output of the diesel engine can the safe operation of the vehicle be guaranteed. In order to ensure the correctness of the injection timing of the diesel engine, it is necessary to monitor the injection timing of the fuel system.

[0003] A comparative document 1 with application number 201811130279.X and titled "Engine Injection Timing Deviation Detection Method and System" discloses an engine injection timing deviation detection method and system, the method comprising: obtaining a pre-calibrated ideal explosion pressure MAP and injection advance angle MAP of the engine; obtaining the actual explosion pressure of the engine; when the actual explosion pressure does not meet the requirements of the ideal explosion pressure MAP, determining that there is a deviation in the engine injection timing.

[0004] The comparative document 2 with application number 201811316265.7 and titled "An online timing detection device for valve timing and fuel injection of an internal combustion engine" discloses an online timing detection device for valve timing and fuel injection of an internal combustion engine. The gear system of the internal combustion engine has a driving injection pump gear, a driving crankshaft gear, a driving camshaft gear and an intermediate gear; the timing detection device also has a plurality of magnetoelectric sensors connected to the speed signal disk: magnetoelectric sensor I, magnetoelectric sensor II, magnetoelectric sensor III, and magnetoelectric sensor IV; magnetoelectric sensor I is arranged on the tooth edge of the speed signal disk; the magnetoelectric sensor II is arranged on the tooth edge of the driving camshaft gear; magnetoelectric sensor III is set on the tooth edge of the driving injection pump gear; magnetoelectric sensor IV is a plurality of magnetoelectric sensors transferred to the injection pump.

[0005] In the existing technical solution, Comparative Document 1 measures the actual explosion pressure by installing an explosion pressure sensor. This method requires the use of a combustion analyzer and a cylinder pressure sensor, so this method is mostly used for bench tests during the development process and cannot solve the problem of real-time monitoring of explosion pressure during mass production. Comparative Document 2 requires additional sensor parts, which increases costs, is complex to assemble, and has high maintenance costs in the later stage, is prone to problems, and is difficult to repair. Summary of the invention

[0006] The purpose of the present invention is to solve the above-mentioned shortcomings of the background technology and provide a method for accurately monitoring the injection timing of the fuel system without adding additional sensor parts.

[0007] To achieve this purpose, the fuel system injection timing monitoring method designed by the present invention includes reading the injection related signal, calculating the single tooth cycle according to the engine speed, and calculating the injection reference tooth number according to the injection related signal and the single tooth cycle;

[0008] Calculate the time difference between the timestamp of the falling edge of the injection reference tooth and the injection interruption moment according to the injection reference tooth number, the single tooth cycle and the injection related signal;

[0009] Calculate the number of crankshaft teeth from the injection reference tooth to the injection top dead center of the current injection cylinder, read the injection angular velocity, determine the angle between two adjacent crankshaft teeth of the crankshaft disk, and calculate the actual injection timing according to the number of crankshaft teeth from the injection reference tooth to the injection top dead center of the current injection cylinder, the injection angular velocity, the time difference between the falling edge of the injection reference tooth and the injection interruption, and the angle between two adjacent crankshaft teeth of the crankshaft disk;

[0010] Determine whether the actual injection timing is within the set injection threshold range and whether the difference between the actual injection timing and the set injection timing is within the set injection deviation threshold range. If the above two judgment conditions are met at the same time, the injection timing is normal. If the above two judgment conditions cannot be met at the same time, the injection timing is faulty.

[0011] Furthermore, the reading of the injection-related signal includes reading the timestamp of the falling edge of the previous tooth of the crankshaft tooth at the end of the injection, the timestamp of the injection start time, and the tooth number of the previous tooth of the crankshaft tooth at the end of the injection.

[0012] Furthermore, the single tooth period is the time required for the camshaft to rotate one tooth; the calculation formula for the single tooth period is: The Tooth Period is the single tooth period, N is the number of teeth on the crankshaft disk, speed is the engine speed in revolutions per minute, and the unit of the single tooth period is us.

[0013] Furthermore, the method for calculating the injection reference tooth number based on the injection-related signal and a single tooth cycle is: substitute the timestamp of the falling edge of the previous tooth of the crankshaft tooth at the end of the injection, the timestamp of the start of the injection, the tooth number of the previous tooth of the crankshaft tooth at the end of the injection, and the single tooth cycle into the calculation formula of the injection reference tooth number to obtain the injection reference tooth number.

[0014] Furthermore, the calculation formula of the injection reference tooth number is: CTP =N stp -(

(T stoptooth -T start ) / Tooth period

[0015] Furthermore, the method for calculating the time difference between the timestamp of the falling edge of the injection reference tooth and the injection interruption moment according to the injection reference tooth number, the single tooth cycle and the injection-related signal is: calculating the crankshaft rotation time T1 between the previous tooth of the crankshaft tooth at the end of injection and the injection reference tooth, and calculating the crankshaft rotation time T2 between the crankshaft tooth at the end of injection and the injection interruption moment, and the difference between T1 and T2 is the time difference T0 between the timestamp of the falling edge of the injection reference tooth and the injection interruption moment.

[0016] Furthermore, the calculation formula of the crankshaft rotation time T1 between the previous tooth of the crankshaft tooth at the injection end time and the injection reference tooth is: T1 = (N stop -N CTP )×Tooth period The calculation formula of the crankshaft rotation time T2 between the crankshaft tooth at the end of injection and the injection interruption time is: T2 = T stoptooth -T start .

[0017] Furthermore, the method for calculating the actual injection timing based on the number of crankshaft teeth from the injection reference tooth to the injection top dead center of the current injection cylinder, the injection angular velocity, the time difference between the falling edge of the injection reference tooth and the injection interruption, and the angle between two adjacent crankshaft teeth of the crankshaft disk is: substitute the number of crankshaft teeth from the injection reference tooth to the injection top dead center of the current injection cylinder, the injection angular velocity, the time difference between the falling edge of the injection reference tooth and the injection interruption, and the angle between two adjacent crankshaft teeth of the crankshaft disk into the calculation formula of the actual injection timing to obtain the actual injection timing.

[0018] Furthermore, the calculation formula of the actual injection timing is: injection =N injection ×α-T0×W,E injection is the actual injection timing, the N injectionis the number of crankshaft teeth from the injection reference tooth to the injection top dead center of the current injection cylinder, α is the angle between the two adjacent crankshaft teeth, and W is the injection angular velocity.

[0019] Furthermore, the method for monitoring the injection timing of the fuel system comprises the following steps:

[0020] Step 1: Read the injection-related signal, calculate the single tooth cycle according to the engine speed, and calculate the injection reference tooth number according to the injection-related signal and the single tooth cycle;

[0021] Step 2: Calculate the time difference between the timestamp of the falling edge of the injection reference tooth and the injection interruption moment according to the injection reference tooth number, the single tooth cycle and the injection related signal;

[0022] Step 3: Calculate the number of crankshaft teeth from the injection reference tooth to the injection top dead center of the current injection cylinder, read the injection angular velocity, and determine the angle between two adjacent crankshaft teeth of the crankshaft disk;

[0023] Step 4: Calculate the actual injection timing according to the number of crankshaft teeth from the injection reference tooth to the injection top dead center of the current injection cylinder, the injection angular velocity, the time difference between the falling edge of the injection reference tooth and the injection interruption, and the angle between two adjacent crankshaft teeth of the crankshaft disk;

[0024] Step 5: Determine whether the actual injection timing is within the set injection threshold range and whether the difference between the actual injection timing and the set injection timing is within the set injection deviation threshold range. If the above two judgment conditions are met at the same time, the injection timing is normal. If the above two judgment conditions cannot be met at the same time, the injection timing is faulty.

[0025] The beneficial effects of the present invention are as follows: the monitoring method designed by the present invention can accurately calculate the actual injection timing without the aid of other external devices or sensors, thereby reducing the development cost. By judging whether the actual injection timing is within the timing range allowed by the engine, the judgment conclusion of abnormal injection and normal injection can be obtained, and the abnormal injection can be identified to reduce the impact on emissions and noise. When an error in the injection timing is monitored, the engine and the entire vehicle can be put into a safe state by limiting the engine injection, thereby reducing the unexpected torque output caused by the injection timing failure and ensuring the driving safety of the entire vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a flow chart of the method for monitoring the injection timing of the fuel system in the present invention;

[0027] Figure 2 is a schematic diagram of the time and injection reference teeth in the present invention; DETAILED DESCRIPTION

[0028] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0029] like Figure 1-2 The fuel system injection timing monitoring method shown includes the following steps:

[0030] Step 1: Read the injection-related signal, calculate the single tooth cycle according to the engine speed, and calculate the injection reference tooth number according to the injection-related signal and the single tooth cycle;

[0031] Step 2: Calculate the time difference between the timestamp of the falling edge of the injection reference tooth and the injection interruption moment according to the injection reference tooth number, a single tooth cycle and the injection related signal;

[0032] Step 3: Calculate the number of crankshaft teeth from the injection reference tooth to the injection top dead center of the current injection cylinder, read the injection angular velocity, and determine the angle between two adjacent crankshaft teeth of the crankshaft disk;

[0033] Step 4: Calculate the actual injection timing according to the number of crankshaft teeth from the injection reference tooth to the injection top dead center of the current injection cylinder, the injection angular velocity, the time difference between the falling edge of the injection reference tooth and the injection interruption, and the angle between two adjacent crankshaft teeth of the crankshaft disk;

[0034] Step 5: Determine whether the actual injection timing is within the set injection threshold range and whether the difference between the actual injection timing and the set injection timing is within the set injection deviation threshold range. If the above two judgment conditions are met at the same time, the injection timing is normal. If the above two judgment conditions cannot be met at the same time, the injection timing is faulty.

[0035] Reading the injection-related signal includes reading the timestamp of the falling edge of the previous tooth of the crankshaft tooth at the end of the injection, the timestamp of the injection start time, and the tooth number of the previous tooth of the crankshaft tooth at the end of the injection.

[0036] A single tooth cycle is the time required for the camshaft to rotate one tooth; the calculation formula for a single tooth cycle is: Tooth Period is a single tooth cycle, N is the number of teeth on the crankshaft, speed is the engine speed in revolutions per minute, and the unit of a single tooth cycle is u s .

[0037] The method for calculating the injection reference tooth number based on the injection-related signal and a single tooth cycle is: substitute the timestamp of the falling edge of the previous tooth of the crankshaft tooth at the end of injection, the timestamp of the start of injection, the tooth number of the previous tooth of the crankshaft tooth at the end of injection and a single tooth cycle into the calculation formula of the injection reference tooth number to obtain the injection reference tooth number.

[0038] The calculation formula for the injection reference tooth number is:

[0039] N CTP =N stop -(

(T stoptooth -T start ) / Tooth period

[0040] The method for calculating the time difference between the timestamp edge of the injection reference tooth and the injection interruption according to the injection reference tooth number, a single tooth cycle and the injection-related signal is: calculate the crankshaft rotation time T1 between the previous tooth of the crankshaft tooth at the end of injection and the injection reference tooth, calculate the crankshaft rotation time T2 between the crankshaft tooth at the end of injection and the injection interruption moment, and the difference between T1 and T2 is the time difference T0 between the timestamp edge of the injection reference tooth and the injection interruption moment.

[0041] The calculation formula of the crankshaft rotation time T1 between the previous tooth of the crankshaft tooth and the injection reference tooth at the end of injection is: T1 = (N stop -N CTP )×Tooth priod The calculation formula of the crankshaft rotation time T2 between the end of injection and the injection interruption time is: T2-T stoptooth -T start .

[0042] The method for calculating the actual injection timing based on the number of crankshaft teeth from the injection reference tooth to the injection top dead center of the current injection cylinder, the injection angular velocity, the time difference between the falling edge of the injection reference tooth and the injection interruption, and the angle between two adjacent crankshaft teeth of the crankshaft disk is as follows: substitute the number of crankshaft teeth from the injection reference tooth to the injection top dead center of the current injection cylinder, the injection angular velocity, the time difference between the falling edge of the injection reference tooth and the injection interruption, and the angle between two adjacent crankshaft teeth of the crankshaft disk into the calculation formula of the actual injection timing to obtain the actual injection timing.

[0043] The calculation formula for the actual injection timing is: F injection=N injection ×α-T0×W,E injection is the actual injection timing, N injection is the number of crankshaft teeth from the injection reference tooth to the injection top dead center of the current injection cylinder, α is the angle between two adjacent crankshaft teeth, and W is the injection angular velocity.

[0044] Take a fuel injection of cylinder 1 as an example. Assuming that after the fuel injection is completed, the three signals fed back to the application layer by the bottom layer are: T stoptooth =2000us, T start =1100us, N stop =57, the tooth period is calculated according to the current engine speed. The current engine speed is 1200rpm, which is converted into a tooth period of 833us. Based on these parameters, the injection reference tooth is calculated as NCTP=57-([(2000-1100) / 833]+1)=55.

[0045] According to the calculation result of step 1, calculate T0 = (57-55) × 833-(2000-1100) = 766us. injection =N injection ×α-T0×W is to calculate the angle between the injection time and the injection top dead center. In this formula, N injection It is the number of crankshaft teeth from the injection reference tooth to the injection top dead center. There are 60 teeth in one circle of our engine crankshaft teeth, so each tooth is 6°. The number of teeth multiplied by 6° can calculate the angle of the injection reference tooth from the top dead center. Taking a certain injection of the engine cylinder 1 as an example, the top dead center of the 1st cylinder is the 60th tooth of the crankshaft tooth, and the calculated injection reference tooth is the 55th tooth. The angle of the injection reference tooth from the top dead center is (60-55)×6=30°, but the injection reference tooth is not the moment when the injection task is being performed. 10 refers to the time from the falling edge of the injection reference tooth to the injection interruption. T0×W is to calculate the angle within this time. Assuming that T0=766us and W=0.0072° / us calculated above, the angle within T0 is 766×0.0072=5.5°, and the actual injection timing is 30-5.5=24.5°.

[0046] The number of teeth N in calculating the injection reference tooth distance from the injection top dead center injection When the value of N is used, the calculation is different according to the number of engine cylinders and the injection type of each cylinder. Taking a six-cylinder diesel engine as an example, the crankshaft tooth numbers NTDC corresponding to the injection top dead center of cylinders 1-6 are (60, 80, 100, 120, 20, 40) respectively. In general, N injction The calculation formula is: N injection =

N TDC -N CTP

[0047] The post-injection of the 4th cylinder occurs between the 1st and 20th teeth of the crankshaft. injection The calculation formula is: injection =

N TDC -N CTP

[0048] The pilot injection of the 5th cylinder may occur before the 120th crankshaft tooth. If this is the case,

[0049] N injection The calculation formula is: injection =

N TDC -N CTP

[0050] N injection After the calculation is completed, the timing calculation can be performed. When the calculation result is positive, it means that the pre-injection and main injection are on time. When the calculation result is negative, it means that the post-injection is on time.

[0051] Specific application example: Calculate the actual timing E according to the calculation results of steps 1 and 2 injetion First, we need to calculate the injection angular velocity W, which is still calculated based on the engine speed of 1200rpm, W = 0.0072° / us,

[0052] E injection =(60-55)×6-766×0.0072=24.5°, the actual timing is 24.5°.

[0053] Determine whether the actual timing is within the timing range allowed by the engine

[0054] The fuel injection of the engine includes pre-injection, main injection and post-injection. The allowable range of injection timing is generally within a certain range before and after the top dead center. The threshold value may be different for different engines. According to the actual timing, it can be judged whether the actual timing is within the allowable threshold range. If it exceeds the threshold, it is considered that this injection is abnormal and the injection timing fault is directly reported;

[0055] If the actual injection timing is within the threshold range allowed by the engine, the deviation between the actual injection timing and the set injection timing is calculated; when the deviation between the actual injection timing and the set injection timing exceeds a certain threshold, an injection timing fault can be diagnosed. For example, assuming that the threshold range of the set injection is 60° at the top dead center, the actual timing is 24.5° within the threshold range.

[0056] Assuming that the set injection timing is 21°, the allowed deviation between the actual injection timing and the set injection timing is 2°. At this time, 24.5° exceeds the threshold and an injection timing fault is reported.

[0057] The monitoring method designed by the present invention can accurately calculate the actual injection timing without the help of other external devices or sensors, thus reducing the development cost. By judging whether the actual injection timing is within the timing range allowed by the engine, the judgment conclusion of abnormal injection and normal injection can be obtained, and the abnormal injection can be identified to reduce the impact on emissions and noise. When the injection timing is monitored to be wrong, the engine injection can be limited to put the engine and the whole vehicle into a safe state, reducing the unexpected torque output caused by the injection timing failure, and ensuring the driving safety of the whole vehicle.

[0058] It should be noted that the description of the above technical solutions is exemplary, and this specification can be embodied in different forms and should not be interpreted as being limited to the technical solutions set forth herein. On the contrary, providing these descriptions will make the disclosure of the present invention thorough and complete, and will fully convey the scope disclosed in this specification to those skilled in the art. In addition, the technical solutions of the present invention are limited only by the scope of the claims.

[0059] When the detailed description of related known functions or configurations is determined to unnecessarily obscure the key points of the present specification and claims, the detailed description will be omitted.

[0060] Finally, it should be pointed out that the above embodiments are only representative examples of the present invention. Obviously, the present invention is not limited to the above embodiments, and there are many variations. Any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention should be considered to belong to the protection scope of the present invention.

Claims

1. A method for monitoring injection timing of a fuel system, characterized in that: Read the injection related signal, calculate the single tooth cycle according to the engine speed, and calculate the injection reference tooth number according to the injection related signal and the single tooth cycle; Calculate the time difference between the timestamp of the falling edge of the injection reference tooth and the injection interruption moment according to the injection reference tooth number, the single tooth cycle and the injection related signal; Calculate the number of crankshaft teeth from the injection reference tooth to the injection top dead center of the current injection cylinder, read the injection angular velocity, determine the angle between two adjacent crankshaft teeth of the crankshaft disk, and calculate the actual injection timing according to the number of crankshaft teeth from the injection reference tooth to the injection top dead center of the current injection cylinder, the injection angular velocity, the time difference between the falling edge of the injection reference tooth and the injection interruption, and the angle between two adjacent crankshaft teeth of the crankshaft disk; Determine whether the actual injection timing is within the set injection threshold range and whether the difference between the actual injection timing and the set injection timing is within the set injection deviation threshold range. If both of the above judgment conditions are met at the same time, the injection timing is normal. If both of the above judgment conditions cannot be met at the same time, the injection timing is faulty. The injection angular velocity is the rotational angular velocity of the engine.

2. The method for monitoring the injection timing of a fuel system according to claim 1, characterized in that: The reading of the injection-related signal includes reading the timestamp of the falling edge of the previous tooth of the crankshaft tooth at the end of the injection, the timestamp of the injection start time, and the tooth number of the previous tooth of the crankshaft tooth at the end of the injection.

3. The method for monitoring the injection timing of a fuel system according to claim 2, characterized in that: The single tooth cycle is the time required for the camshaft to rotate one tooth; the calculation formula of the single tooth cycle is: The Tooth Period is the single tooth period, N is the number of teeth on the crankshaft disk, speed is the engine speed in revolutions per minute, and the unit of the single tooth period is us.

4. The method for monitoring the injection timing of a fuel system according to claim 3, characterized in that: The method for calculating the injection reference tooth number based on the injection-related signal and a single tooth cycle is: substitute the timestamp of the falling edge of the previous tooth of the crankshaft tooth at the end of the injection, the timestamp of the start of the injection, the tooth number of the previous tooth of the crankshaft tooth at the end of the injection, and the single tooth cycle into the calculation formula of the injection reference tooth number to obtain the injection reference tooth number.

5. The method for monitoring the injection timing of a fuel system according to claim 4, characterized in that: The calculation formula of the injection reference tooth number is: N CTP =N stop -(【(T stoptooth -T start ) / Tooth period 】+1), the N CTP is the injection reference tooth number, the N stop is the tooth number of the crankshaft tooth before the injection end time, and the T stoptooth is the timestamp of the falling edge of the previous crankshaft tooth at the end of the injection, and the T start is the timestamp of the injection start time.

6. The method for monitoring the injection timing of a fuel system according to claim 5, characterized in that: The method for calculating the time difference between the timestamp of the falling edge of the injection reference tooth and the injection interruption time according to the injection reference tooth number, the single tooth cycle and the injection-related signal is as follows: calculate the crankshaft rotation time T1 between the previous tooth of the crankshaft tooth at the end of injection and the injection reference tooth, calculate the crankshaft rotation time T2 between the crankshaft tooth at the end of injection and the injection interruption time, and the difference between T1 and T2 is the time difference T0 between the timestamp of the falling edge of the injection reference tooth and the injection interruption time.

7. The method for monitoring the injection timing of a fuel system according to claim 6, characterized in that: The calculation formula of the crankshaft rotation time T1 between the previous tooth of the crankshaft tooth at the end of the injection and the injection reference tooth is: T1 = (N stop -N CTP )×Tooth period The calculation formula of the crankshaft rotation time T2 between the crankshaft tooth at the end of injection and the injection interruption time is: T2 = T stoptooth -T start .

8. The method for monitoring the injection timing of a fuel system according to claim 7, characterized in that: The method for calculating the actual injection timing based on the number of crankshaft teeth from the injection reference tooth to the injection top dead center of the current injection cylinder, the injection angular velocity, the time difference between the falling edge of the injection reference tooth and the injection interruption, and the angle between two adjacent crankshaft teeth of the crankshaft disk is as follows: the number of crankshaft teeth from the injection reference tooth to the injection top dead center of the current injection cylinder, the injection angular velocity, the time difference between the falling edge of the injection reference tooth and the injection interruption, and the angle between two adjacent crankshaft teeth of the crankshaft disk are substituted into the calculation formula of the actual injection timing to obtain the actual injection timing.

9. The method for monitoring the injection timing of a fuel system according to claim 8, characterized in that: The calculation formula of the actual injection timing is: injection =N injection ×α-T0×W,E injection is the actual injection timing, the N injection is the number of crankshaft teeth from the injection reference tooth to the injection top dead center of the current injection cylinder, α is the angle between the two adjacent crankshaft teeth, and W is the injection angular velocity.

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