Split-cylinder random fuel injection phase control method and structure of direct injection engine

Abstract

The invention relates to a split-cylinder random fuel injection phase control method and structure for a direct injection engine, and the method comprises the following steps: under an idle working condition, on the basis of the distance of 180 CA degrees between fuel injection pulse widths of cylinders of a four-cylinder engine under a non-idle working condition, increasing the maximum standard fuel injection phase angle deviation offset max, and in the range of the maximum standard oil injection phase angle deviation (offset max), the oil injection phase angle deviation (offset max) is randomly called, and the oil injection phase angle deviation (offset max) comprises an offset 1 (offset max), an offset 2 (offset max), an offset 3 (offset max) and an offset 4 (offset max). Compared with the prior art, rotating speed fluctuation generated by combustion deviation of the engine is offset, and the idling stability is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of engine electronic control systems, and relates to a direct injection engine cylinder random injection phase control method and structure. Background Art

[0002] As the country's requirements for automobile emissions become increasingly stringent and consumers have increasingly higher requirements for the driving of the entire vehicle, higher requirements are placed on the precise control of the engine's fuel. Due to factors such as the material and layout of the engine's fuel system, fuel pulsation will occur during the injection process, and different pulsating pressures will be generated at each injector, resulting in uneven injection of the engine's cylinders. Especially for direct injection engines (GDI) that use a high-pressure fuel system, the fuel rail generally adopts a design without a damper, and the impact of fuel pulsation is greater. If the fuel in the engine cylinder is too lean, there will be excess oxygen after the oil and gas are mixed. Under the high-temperature and oxygen-rich combustion state, the engine nitrogen oxides (NO x ) original emissions; if the fuel in the engine cylinder is too rich, the unburned mixture will be discharged from the cylinder, which will increase the emissions of hydrocarbons (HC) and carbon monoxide (CO). At the same time, uneven fuel injection in each cylinder will lead to different combustion explosion pressures in each cylinder of the engine, causing the engine to run unsteadily, especially in the idling stage. The unsteady engine operation leads to obvious speed fluctuations, which are transmitted to the vehicle cockpit through the transmission system, causing a bad driving experience.

[0003] In order to reduce idle speed fluctuations and improve driving experience, the traditional GDI engine control method is to increase the idle speed, increase the actual air intake entering the engine, improve the engine control robustness, and reduce speed fluctuations. However, this solution increases idle fuel consumption due to the increase in speed.

[0004] Patent CN101694184A discloses an engine start injection control method, which determines the injector opening time according to the fuel injection time, and determines the injector opening duration according to the fuel injection pulse width; wherein the fuel injection time and the fuel injection cylinder number are determined according to the detected engine crankshaft signal and phase signal; the fuel injection pulse width is determined according to the detected engine temperature, and compensated according to the detected battery voltage. However, the patent does not explain in detail the specific calculation method of the injection reference tooth and the injection phase, which has limitations.

[0005] Patent CN114542311A discloses a method and system for controlling direct injection in a cylinder of a direct injection engine under low temperature conditions. The critical crankshaft angle corresponding to the injection wall wetted by the fuel injection is calculated based on the basic parameters of the fuel injector and the combustion system; the injection parameters of the fuel injector are calibrated based on the calibration principle that the calibrated injection end angle is less than the critical crankshaft angle; it is determined whether the direct injection engine is in a low temperature environment. If it is in a low temperature environment, the fuel injector is controlled to execute the injection parameters to complete the direct injection of gasoline in the cylinder under low temperature conditions. However, this patent tries to avoid oil dilution as much as possible from the calibration level and provides a basis for the selection of the injection phase. It does not explain the injection phase reference and range from the system logic level, and cannot solve the speed fluctuation problem at idle speed. Summary of the invention

[0006] The purpose of the present invention is to provide a direct injection engine cylinder random injection phase control method and structure in order to overcome at least one defect of the above-mentioned prior art. Under idle conditions, the present invention realizes random changes in the injection timing of each cylinder on the direct injection engine within a calibrable range, offsets the speed fluctuation caused by engine combustion deviation, and improves idle stability.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] One of the technical solutions of the present invention is to provide a method for controlling the random injection phase of a direct injection engine cylinder, the method comprising the following steps:

[0009] Under non-idling conditions, the distance between the injection pulse widths of each cylinder of a four-cylinder engine is 180CA° (degrees crankshaft angle);

[0010] Under idle conditions, in order to achieve independent control of the injection timing of each cylinder of the engine, reduce the harmful gas emissions of the engine, reduce the idle speed fluctuation of the engine, and improve the stability of the engine's fuel injection control, the maximum standardizable injection phase angle deviation offset is increased on the basis of the distance between the injection pulse widths of each cylinder of the four-cylinder engine of 180CA°. max , at the maximum adjustable injection phase angle deviation offset max Within the range, the electronic control unit randomly adjusts the injection phase angle deviation offset random ∈(-|offset max |,|offset max |), the injection phase angle deviation offset random Including the first cylinder injection phase angle deviation offset1 random 、2nd cylinder injection phase angle deviation offset2 random 、The third cylinder injection phase angle deviation offset3 randomAnd the fourth cylinder injection phase angle deviation offset4 random , under idling conditions, the interval random control of the injection timing of each cylinder can be achieved;

[0011] The injection order of the four-cylinder engine is the first cylinder - the third cylinder - the fourth cylinder - the second cylinder (1-3-4-2), and the injection reference teeth of each cylinder are spaced 180CA° apart;

[0012] The distance between the injection pulse widths of the first cylinder and the third cylinder is 180CA°+offset1 random -offset3 random ;

[0013] The distance between the injection pulse widths of the third cylinder and the fourth cylinder is 180CA°+offset3 random -offset4 random ;

[0014] The distance between the injection pulse width of the fourth cylinder and the second cylinder is 180CA°+offset4 random -offset2 random ;

[0015] The distance between the injection pulse width of the second cylinder and the first cylinder is 180CA°+offset2 random -offset1 random .

[0016] Furthermore, the maximum adjustable injection phase angle deviation offset of each cylinder max The reading is made from a three-dimensional calibratable table, where the X and Y coordinates are the engine speed and load respectively, and the Z coordinate is the maximum calibratable injection phase angle deviation offset. max -180CA°≤offset max ≤180CA°, considering the angle of a complete stroke, determined on the whole vehicle based on the minimum speed fluctuation.

[0017] As a preferred technical solution, the injection timing needs to be calculated based on the crank angle and intake valve timing angle signals.

[0018] Furthermore, the crank signal disc is a 60-2 (58) tooth structure, wherein 58 teeth are designed with evenly spaced tooth tops and tooth grooves, and 2 teeth are designed with missing teeth;

[0019] The crank position sensor measures and inputs a 60-2 tooth signal to the electronic control unit. For every rotation of the engine, the electronic control unit obtains a complete 60-2 tooth signal, with each tooth representing 6CA°.

[0020] Furthermore, the falling edge of the 20th tooth signal is set to the compression top dead center (TDC1) of the first cylinder of the engine, which generally requires the engine to be designed to ensure the size of the crank signal plate, tooth groove / tooth top design, installation angle, etc.

[0021] Furthermore, the falling edge of the 17th tooth in a complete 60-2 tooth signal before the compression top dead center of the first cylinder is set as the injectable start tooth of the first cylinder, which is logically advanced by 3 teeth to reserve space for the injection phase. In principle, the exhaust stroke injection of the engine in the previous cycle can be realized, which can be used in special scenarios. For example, in the cold engine state, in order to prevent oil dilution, a part of the fuel is sprayed into the cylinder at the end of the exhaust stage, and the residual temperature in the cylinder is used to heat the fuel.

[0022] Furthermore, the falling edge of the 23rd tooth in the complete 60-2 tooth signal where the compression top dead center of the first cylinder is located is set as the injection end tooth of the first cylinder, and logically lags behind by 3 teeth to reserve space for the injection phase. In theory, it can be achieved that the injection continues briefly during the power stroke, and compensates for the small flow of the injector in special scenarios;

[0023] Theoretically, fuel can be injected between the fuel injection start tooth and the fuel injection end tooth, and the fuel injection start tooth timing and the fuel injection end tooth timing are set as the fuel injection boundary line.

[0024] Further, the compression top dead center of the first cylinder is set as the injection reference tooth;

[0025] The phase length from the opening moment angle of the injection pulse width to the injection reference tooth is set as the injection angle SOI (start of injection). The injection angle SOI can be calibrated and can be positive or negative. It is selected on the test bench according to the optimal fuel consumption of the engine.

[0026] Further, the injection reference tooth of the third cylinder is set to the falling edge of the 50th tooth in the complete 60-2 tooth signal where the compression top dead center of the first cylinder is located;

[0027] The injection reference tooth of the fourth cylinder is set to the falling edge of the 20th tooth in a complete 60-2 tooth signal after the compression top dead center of the first cylinder;

[0028] The injection reference tooth of the second cylinder is set to the falling edge of the 50th tooth in a complete 60-2 tooth signal after the compression top dead center of the first cylinder.

[0029] Furthermore, under the idling condition, the phase length from the opening angle of the random injection pulse width of each cylinder with the random phase function turned on to the injection reference tooth is as follows:

[0030] The phase length from the opening angle of the random injection pulse width of the first cylinder to the injection reference tooth is SOI+offset1 random;

[0031] The phase length from the opening angle of the random injection pulse width of the second cylinder to the injection reference tooth is SOI+offset2 random ;

[0032] The phase length from the opening angle of the random injection pulse width of the third cylinder to the injection reference tooth is SOI+offset3 random ;

[0033] The phase length from the opening angle of the random injection pulse width of the fourth cylinder to the injection reference tooth is SOI+offset4 random .

[0034] One of the technical solutions of the present invention is to provide a direct injection engine cylinder random injection phase control structure, which implements the method described, the engine is electrically connected to an electronic control unit (ECU), and the electronic control unit stores a chart required for calculation, and the structure includes a low-voltage part and a high-voltage part;

[0035] In the low-pressure part, the fuel tank is connected to a fuel pump, the fuel pump is connected to a low-pressure pipeline, and the fuel pump is electrically connected to an electronic control unit;

[0036] In the high-pressure part, a high-pressure oil pump is connected to the low-pressure pipeline and the high-pressure pipeline, and the high-pressure oil pump is electrically connected to the electronic control unit;

[0037] The high-pressure pipeline is connected to a high-pressure oil rail, a cylinder and a crankshaft are arranged in the engine, the high-pressure oil rail is connected to an injector, the high-pressure oil rail sprays oil into the cylinder through the injector, one end of the crankshaft extending out of the cylinder is connected to a crank signal disk, a crank sensor is arranged next to the crank signal disk, and the injector and the crank sensor are electrically connected to an electronic control unit.

[0038] As a preferred technical solution, the fuel tank is connected to the fuel pump through a circulation pipeline.

[0039] As a preferred technical solution, the electronic control unit controls the fuel pump to draw fuel from the fuel tank to the low-pressure pipeline, keeps the oil pressure in the low-pressure pipeline stable, and returns excess fuel to the fuel tank.

[0040] As a preferred technical solution, the high-pressure oil pump is connected to a driving cam.

[0041] As a preferred technical solution, the driving cam is arranged on a camshaft, one end of the camshaft is connected to a cam signal disk, and the other end is connected to a variable valve timing (VVT) phaser, a cam position sensor is arranged next to the cam signal disk, and the variable valve timing phaser and the cam position sensor are electrically connected to an electronic control unit.

[0042] As a preferred technical solution, the driving cam drives the piston of the high-pressure oil pump upward, and the electronic control unit controls the high-pressure oil pump to close the actuator valve of the high-pressure oil pump at an appropriate time, and uses the upward energy of the piston to forcibly pump fuel into the high-pressure pipeline;

[0043] The electronic control unit controls the rotational offset of the variable valve timing phaser, and the rotational offset of the variable valve timing phaser drives the rotational offset of the camshaft, thereby driving the valve lift change to achieve continuous variable valve timing;

[0044] The relative rotation offset information of the variable valve timing phaser is characterized by the offset position of the cam signal disk. The cam position sensor captures the offset position information of the cam signal disk and transmits it to the electronic control unit, which calculates the final variable valve timing phase opening.

[0045] As a preferred technical solution, an oil pressure sensor is provided on the high-pressure oil rail, and the oil pressure sensor is electrically connected to the electronic control unit.

[0046] As a preferred technical solution, the oil pressure sensor measures the pressure information in the high-pressure pipeline in a timely manner and feeds back to the electronic control unit;

[0047] The electronic control unit controls the output drive signal to the high-pressure fuel pump, controls the high-pressure fuel pump switch, and presses in an appropriate amount of fuel to maintain the theoretical fuel rail pressure;

[0048] The electronic control unit calculates the required fuel injection amount of each cylinder's fuel injector in combination with the current engine speed and load information, and calculates the final fuel injection pulse width and fuel injection phase of each cylinder, and outputs them to the fuel injector of each cylinder for execution;

[0049] The crank position sensor feeds back the tooth signal in the crank position signal plate to calculate the actual crankshaft position and speed information of the engine.

[0050] One of the technical solutions of the present invention is to provide a direct injection engine cylinder random injection phase control device, including a memory, a processor, and a computer program stored in the memory, and the processor executes the computer program to implement the steps of the described method.

[0051] One of the technical solutions of the present invention is to provide a computer-readable storage medium on which a computer program is stored, and when the computer program is executed by a processor, the steps of the method described are implemented.

[0052] One of the technical solutions of the present invention is to provide a computer program product, including a computer program, which implements the steps of the method when executed by a processor.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] (1) The present invention relates to a random fuel injection phase control strategy for direct injection engines that can reduce idle speed fluctuations. Under idle conditions, the control system can randomly adjust the fuel injection timing of a cylinder or multiple cylinders within a calibrable time range, so that the fuel injection timings of each cylinder are not equidistant, which is used to offset the pressure pulsation in the fuel system. The fuel injection control method can define different fuel injection timings for each cylinder, so that the fuel injection timing of each cylinder in a stroke of the engine can be independently controlled. The fuel injection timing changes randomly, so that the combustion pressure of each cylinder changes randomly within a controllable range, offsetting the influence of specific cylinder combustion deviations caused by manufacturing deviations and other reasons on speed fluctuations, improving the stability of the engine in the idle stage, and effectively reducing the harmful gas emissions of the engine;

[0055] (2) The present invention adopts random changes in the injection timing of each cylinder of the direct injection engine within a calibrable range under idle conditions to offset the speed fluctuation caused by engine combustion deviation, without increasing the idle speed, reducing idle fuel consumption, and achieving technical cost reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 Schematic diagram of a cylinder-by-cylinder random injection phase control structure of a direct injection engine according to an embodiment of the present invention;

[0057] Figure 2 Schematic diagram of the injection timing control of the first cylinder of a direct injection engine according to an embodiment of the present invention;

[0058] Figure 3 Schematic diagram of random fuel injection phase control for cylinders of a direct injection engine according to an embodiment of the present invention.

[0059] Description of the markings in the figure:

[0060] 1—Fuel tank, 2—Fuel pump, 3—Low-pressure pipeline, 4—Cam position sensor, 5—Cam signal plate, 6—High-pressure fuel pump, 7—Drive cam, 8—Camshaft, 9—Variable valve timing phaser, 10—Engine, 11—Cylinder, 12—High-pressure pipeline, 13—Oil pressure sensor, 14—High-pressure fuel rail, 15—Injector, 16—Crankshaft, 17—Crank signal plate, 18—Crank sensor, 19—Electronic control unit. DETAILED DESCRIPTION

[0061] The present invention is described in detail below in conjunction with specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and a specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0062] Example:

[0063] A direct injection engine cylinder random injection phase control structure, such as Figure 1As shown, the engine 10 is electrically connected to an electronic control unit (ECU) 19, which stores the charts required for calculations, and the structure includes a low-voltage part and a high-voltage part;

[0064] In the low-pressure part, the fuel tank 1 is connected to the fuel pump 2 through a circulation pipeline, the fuel pump 2 is connected to the low-pressure pipeline 3, and the fuel pump 2 is electrically connected to the electronic control unit 19;

[0065] The electronic control unit 19 controls the fuel pump 2 to draw fuel from the fuel tank 1 to the low-pressure pipeline 3, keeps the oil pressure in the low-pressure pipeline 3 stable, and the excess fuel returns to the fuel tank 1;

[0066] In the high-pressure part, the high-pressure oil pump 6 is connected to the low-pressure pipeline 3 and the high-pressure pipeline 12, the high-pressure oil pump 6 is connected to the driving cam 7, and the high-pressure oil pump 6 is electrically connected to the electronic control unit 19;

[0067] The driving cam 7 drives the piston of the high-pressure oil pump 6 upward, and the electronic control unit 19 controls the high-pressure oil pump 6 to close the actuator valve of the high-pressure oil pump 6 at an appropriate time, and uses the upward energy of the piston to forcibly pump fuel into the high-pressure pipeline 12;

[0068] The driving cam 7 is arranged on the camshaft 8, one end of the camshaft 8 is connected to the cam signal plate 5, and the other end is connected to the variable valve timing (VVT) phaser 9. A cam position sensor 4 is arranged next to the cam signal plate 5. The variable valve timing phaser 9 and the cam position sensor 4 are electrically connected to the electronic control unit 15;

[0069] The electronic control unit 19 controls the rotational offset of the variable valve timing phaser 9. The rotational offset of the variable valve timing phaser 9 drives the rotational offset of the camshaft 8, thereby driving the valve lift change to achieve continuous variable valve timing.

[0070] The relative rotation offset information of the variable valve timing phaser 9 is characterized by the offset position of the cam signal plate 5. The cam position sensor 4 captures the offset position information of the cam signal plate 5 and transmits it to the electronic control unit 19, which calculates the final variable valve timing phase opening amount.

[0071] The high-pressure pipeline 12 is connected to the high-pressure oil rail 14, and the high-pressure oil rail 14 is provided with an oil pressure sensor 13. The engine 10 is provided with a cylinder 11 and a crankshaft 16. The high-pressure oil rail 14 is connected to the injector 15. The high-pressure oil rail 14 injects oil into the cylinder 11 through the injector 15. One end of the crankshaft 16 extending out of the cylinder 11 is connected to the crank position signal disk 17. A crank position sensor 18 is provided next to the crank position signal disk 17. The oil pressure sensor 13, the injector 15 and the crank position sensor 18 are electrically connected to the electronic control unit 19.

[0072] The oil pressure sensor 13 measures the pressure information in the high pressure pipeline 12 in a timely manner and feeds back the pressure information to the electronic control unit 19;

[0073] The electronic control unit 19 controls the output drive signal to the high-pressure fuel pump 6, controls the switch of the high-pressure fuel pump 6, and presses in an appropriate amount of fuel to maintain the theoretical fuel rail pressure;

[0074] The electronic control unit 19 calculates the required injection amount of the fuel injector 15 of each cylinder 11 in combination with the current speed and load information of the engine 10, and calculates the final injection pulse width and injection phase of each cylinder 11, and outputs them to the fuel injector 15 of each cylinder 11 for execution;

[0075] The crank position sensor 18 feeds back the gear signal in the crank position signal plate 17 for calculating the actual crankshaft position and speed information of the engine 10 .

[0076] like Figure 2 As shown, the injection timing needs to be calculated based on the crank angle and intake valve timing angle signals;

[0077] The crank signal disc 17 has a 58 (60-2) tooth structure, wherein 58 teeth are designed with evenly spaced tooth tops and tooth grooves, and 2 teeth are designed with tooth gaps;

[0078] The crank position sensor 18 measures and inputs a 60-2 tooth signal to the electronic control unit 19. The electronic control unit 19 obtains a complete 60-2 tooth signal for each rotation of the engine 10. Each tooth represents 6 degrees of crank angle (CA°);

[0079] The falling edge of the 20th tooth signal is set as the compression top dead center (TDC1) of the first cylinder of the engine 10, and the engine 10 is generally required to be designed to ensure the size of the crank signal plate 17, the tooth groove / tooth top design, the installation angle, etc.;

[0080] The falling edge of the 17th tooth in the complete 60-2 tooth signal before TDC1 is set as the fuel injection start tooth of the first cylinder. Logically, 3 teeth are advanced to reserve space for the fuel injection phase. In principle, the exhaust stroke fuel injection of the engine 10 in the previous cycle can be realized. It can be used in special scenarios. For example, in the cold engine state, in order to prevent oil dilution, a part of the fuel is sprayed into the cylinder at the end of the exhaust stage to heat the fuel using the residual temperature in the cylinder;

[0081] The falling edge of the 23rd tooth in the complete 60-2 tooth signal where TDC1 is located is set as the injection end tooth of the first cylinder. Logically, it lags behind by 3 teeth to reserve space for the injection phase. In theory, it can achieve a short-term continuous injection during the power stroke, and make up for the small flow of injector 15 in special scenarios.

[0082] Theoretically, fuel can be injected between the fuel injection start tooth and the fuel injection end tooth, and the fuel injection start tooth timing and the fuel injection end tooth timing are set as the fuel injection boundary line;

[0083] TDC1 is set as the injection reference gear;

[0084] The phase length from the opening moment angle of the injection pulse width to the injection reference tooth is set as the injection angle SOI (start of injection). The injection angle SOI can be calibrated and can be positive or negative. It is selected on the test bench according to the optimal fuel consumption of the engine 10. In this embodiment, SOI=300CA° is preferably used, which means that the injection starts 300CA° forward from TDC1, that is, the injection starts 50 teeth forward from the falling edge of the 20th tooth signal (the falling edge of the 30th tooth in the previous complete 60-2 tooth signal);

[0085] Taking the four-cylinder engine 10 as an example, the injection sequence is the first cylinder - the third cylinder - the fourth cylinder - the second cylinder (1-3-4-2), and the injection reference teeth of each cylinder 11 are spaced 180CA° apart;

[0086] The injection reference tooth of the third cylinder is set to the falling edge of the 50th tooth in the complete 60-2 tooth signal where TDC1 is located;

[0087] The injection reference tooth of the fourth cylinder is set to the falling edge of the 20th tooth in a complete 60-2 tooth signal after TDC1;

[0088] The injection reference tooth for the second cylinder is set to the falling edge of the 50th tooth in a complete 60-2 tooth signal after TDC1.

[0089] A method for controlling the random injection phase of a direct injection engine cylinder is implemented by using the above structure, such as Figure 3 As shown, the specific steps are as follows:

[0090] Under non-idling conditions, the distance between the injection pulse widths of each cylinder 11 is 180CA°;

[0091] Under idle conditions, in order to achieve independent control of the injection timing of each cylinder 11 of the engine 10, reduce the harmful gas emissions of the engine 10, reduce the idle speed fluctuation of the engine 10, and improve the stability of the fuel injection control of the engine 10, a maximum standardizable injection phase angle deviation offset is added on the basis of the distance 180CA° between the injection pulse widths of each cylinder 11. max , at the maximum adjustable injection phase angle deviation offset max Within the range, the electronic control unit 19 randomly adjusts the injection phase angle deviation offset random ∈(-|offset max |,|offset max |), injection phase angle deviation offset random Including the first cylinder injection phase angle deviation offset1 random 、2nd cylinder injection phase angle deviation offset2 random、The third cylinder injection phase angle deviation offset3 random And the fourth cylinder injection phase angle deviation offset4 random , under idling conditions, the interval random control of the injection timing of each cylinder 11 can be achieved;

[0092] The maximum adjustable injection phase angle deviation offset of each cylinder 11 max The three-dimensional calibratable table reading is selected. The X and Y coordinates in the three-dimensional calibratable table are the speed and load of the engine 10 respectively, and the Z coordinate is the maximum calibratable injection phase angle deviation offset. max -180CA°≤offset max ≤180CA°, considering the angle of a complete stroke, determined on the vehicle based on the minimum speed fluctuation;

[0093] In this embodiment, the maximum adjustable injection phase angle deviation offset max The first cylinder injection phase angle deviation is 50CA°, offset1 random The second cylinder injection phase angle deviation is 40CA°, offset2 random The injection phase angle deviation of the third cylinder is 30CA°. random The fourth cylinder injection phase angle deviation is 30CA°, offset4 random is 40CA°;

[0094] The distance between the injection pulse width of the first cylinder and the third cylinder is 180CA°+offset1 random -offset3 random =(180+40-30)CA°=190CA°;

[0095] The distance between the injection pulse widths of the third and fourth cylinders is 180CA°+offset3 random -offset4 random =(180+30-40)CA°=170CA°;

[0096] The distance between the injection pulse width of the fourth cylinder and the second cylinder is 180CA°+offset4 random -offset2 random =(180+40-30)CA°=190CA°;

[0097] The distance between the injection pulse width of the second cylinder and the first cylinder is 180CA°+offset2 random -offset1 random =(180+30-40)CA°=170CA°;

[0098] At this time, under the idling condition, the phase length from the opening angle of the random injection pulse width of each cylinder 11 with the random phase function turned on to the injection reference tooth is as follows:

[0099] The phase length from the opening angle of the random injection pulse width of the first cylinder to the injection reference tooth is SOI+offset1 random =(300+40)CA°=340CA°;

[0100] The phase length from the opening angle of the random injection pulse width of the second cylinder to the injection reference tooth is SOI+offset2 random =(300+30)CA°=330CA°;

[0101] The phase length from the opening angle of the random injection pulse width of the third cylinder to the injection reference tooth is SOI+offset3 random =(300+30)CA°=330CA°;

[0102] The phase length from the opening angle of the random injection pulse width of the fourth cylinder to the injection reference tooth is SOI+offset4 random =(300+40)CA°=340CA°.

[0103] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for controlling the random injection phase of a direct injection engine cylinder, characterized in that: The method comprises the following steps: Under non-idling conditions, the distance between the injection pulse widths of each cylinder of the four-cylinder engine is 180CA°; Under idle conditions, the maximum adjustable injection phase angle deviation offset is increased based on the distance between the injection pulse widths of each cylinder of a four-cylinder engine of 180CA.° max , at the maximum adjustable injection phase angle deviation offset max Randomly call the injection phase angle deviation offset within the range random ∈(-|offset max |,|offset max |), the injection phase angle deviation offset random Including the first cylinder injection phase angle deviation offset1 random 、2nd cylinder injection phase angle deviation offset2 random 、The third cylinder injection phase angle deviation offset3 random And the fourth cylinder injection phase angle deviation offset4 random ; The injection order of the four-cylinder engine is the first cylinder - the third cylinder - the fourth cylinder - the second cylinder, and the injection reference teeth of each cylinder are 180CA° apart; The distance between the injection pulse widths of the first cylinder and the third cylinder is 180CA°+offset1 random -offset3 random ; The distance between the injection pulse widths of the third cylinder and the fourth cylinder is 180CA°+offset3 random -offset4 random ; The distance between the injection pulse width of the fourth cylinder and the second cylinder is 180CA°+offset4 random -offset2 random ; The distance between the injection pulse width of the second cylinder and the first cylinder is 180CA°+offset2 random -offset1 random .

2. The method for controlling the random fuel injection phase of a direct injection engine according to claim 1, characterized in that: The maximum adjustable injection phase angle offset of each cylinder max The reading is made from a three-dimensional calibratable table, where the X and Y coordinates are the engine speed and load respectively, and the Z coordinate is the maximum calibratable injection phase angle deviation offset. max -180CA°≤offset max ≤180CA°.

3. The method for controlling the random fuel injection phase of a direct injection engine according to claim 1, characterized in that: The crank signal plate has a 60-2 tooth structure, of which 58 teeth are designed with evenly spaced tooth tops and tooth grooves, and 2 teeth are designed with tooth gaps, and each tooth represents 6CA°.

4. The method for controlling the random fuel injection phase of a direct injection engine according to claim 3, characterized in that: The falling edge of the 20th tooth signal is set as the compression top dead center of the first cylinder of the engine.

5. The method for controlling the random fuel injection phase of a direct injection engine according to claim 4, characterized in that: The falling edge of the 17th tooth in a complete 60-2 tooth signal before the compression top dead center of the first cylinder is set as the injection start tooth of the first cylinder.

6. The method for controlling the random fuel injection phase of a direct injection engine cylinder according to claim 5, characterized in that: The falling edge of the 23rd tooth in the complete 60-2 tooth signal where the compression top dead center of the first cylinder is located is set as the injection end tooth of the first cylinder; The injection start tooth timing and the injection end tooth timing are set as the injection boundary line.

7. The method for controlling the random fuel injection phase of a direct injection engine according to claim 4, characterized in that: The compression top dead center of the first cylinder is set as the injection reference tooth; The phase length from the opening moment angle of the injection pulse width to the injection reference tooth is set as the injection angle SOI.

8. The method for controlling the random fuel injection phase of a direct injection engine according to claim 7, characterized in that: The injection reference tooth of the third cylinder is set to the falling edge of the 50th tooth in the complete 60-2 tooth signal where the compression top dead center of the first cylinder is located; The injection reference tooth of the fourth cylinder is set to the falling edge of the 20th tooth in a complete 60-2 tooth signal after the compression top dead center of the first cylinder; The injection reference tooth of the second cylinder is set to the falling edge of the 50th tooth in a complete 60-2 tooth signal after the compression top dead center of the first cylinder.

9. The method for controlling the random fuel injection phase of a direct injection engine cylinder by cylinder according to claim 8, characterized in that: Under idling conditions, the phase length from the opening angle of the random injection pulse width of each cylinder with the random phase function turned on to the injection reference tooth is as follows: The phase length from the opening angle of the random injection pulse width of the first cylinder to the injection reference tooth is SOI+offset1 random ; The phase length from the opening angle of the random injection pulse width of the second cylinder to the injection reference tooth is SOI+offset2 random ; The phase length from the opening angle of the random injection pulse width of the third cylinder to the injection reference tooth is SOI+offset3 random ; The phase length from the opening angle of the random injection pulse width of the fourth cylinder to the injection reference tooth is SOI+offset4 random .

10. A direct injection engine cylinder random injection phase control structure, characterized in that: The structure implements the method as claimed in any one of claims 1 to 9, the engine (10) is electrically connected to the electronic control unit (19), and the structure includes a low-voltage part and a high-voltage part; In the low-pressure part, the fuel tank (1) is connected to a fuel pump (2), the fuel pump (2) is connected to a low-pressure pipeline (3), and the fuel pump (2) is electrically connected to an electronic control unit (19); In the high-pressure part, a high-pressure oil pump (6) is connected to a low-pressure pipeline (3) and a high-pressure pipeline (12), and the high-pressure oil pump (6) is electrically connected to an electronic control unit (19); The high-pressure pipeline (12) is connected to a high-pressure oil rail (14); a cylinder (11) and a crankshaft (16) are arranged in the engine (10); the high-pressure oil rail (14) is connected to an injector (15); the high-pressure oil rail (14) injects oil into the cylinder (11) through the injector (15); one end of the crankshaft (16) extending out of the cylinder (11) is connected to a crank position signal disk (17); a crank position sensor (18) is arranged next to the crank position signal disk (17); the injector (15) and the crank position sensor (18) are electrically connected to an electronic control unit (19).

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