Method and system for controlling methanol injection time of diesel and methanol dual-fuel engine

By combining the crankshaft and cam sensor with software sequence, the injection time of methanol in diesel methanol dual-fuel engine is accurately controlled, which solves the problem of inaccurate methanol injection in the existing technology, and realizes the optimal point of methanol combustion at the cylinder, avoids fire out of the main engine and risk of leakage.

CN119122694APending Publication Date: 2024-12-13青岛淄柴博洋柴油机股份有限公司
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Patent Information

Application Number
CN202411179109.6
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2024-08-27
Publication Date
2024-12-13

AI Technical Summary

Technical Problem

The prior art cannot accurately control the injection time of methanol in diesel methanol dual-fuel engines, resulting in methanol being unable to burn at the optimal moment, which may cause the risk of main engine shutdown and methanol leakage.

Method used

Through the crankshaft phase sensor and camshaft phase sensor combined with the ignition sequence set by the software, the work top dead center of each cylinder is found, and the methanol injection time is determined using this as a reference to ensure that methanol is at the best point for combustion of the cylinder. The specific steps include determining the position of the crankshaft and cam, setting the threshold, adjusting the injection timing, and ensuring that methanol is sprayed within 2.7°-7.5° of the crankshaft angle before the exhaust valve is closed.

Benefits of technology

Accurate control of methanol injection time is achieved, ensuring that methanol is at the best point of combustion of the cylinder, avoiding methanol spraying walls or front spraying back spraying, and improving combustion efficiency and safety.

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Abstract

The invention belongs to the technical field of diesel and methanol dual-fuel engines, and discloses a method and a system for controlling methanol injection time of a diesel and methanol dual-fuel engine. The method comprises the following steps: finding out an acting top dead center of a cylinder 1 through a crankshaft phase sensor and a camshaft phase sensor; according to an ignition sequence set by software, an acting top dead center of each cylinder is found in sequence; and a gas supply top dead center is found by taking an acting top dead center as a reference, and a base point is found for methanol injection. According to the operation method, the methanol injection time can be accurately controlled, and the optimal point of methanol entering the air cylinder for combustion is achieved. The air supply timing of the engine is accurately controlled, the methanol spraying time is accurately controlled on this basis, methanol is sprayed at the optimal time, and the situation that methanol cannot accurately enter an air cylinder for combustion due to the fact that methanol is sprayed on the wall or sprayed forwards and backwards is avoided.
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Description

Technical Field

[0001] The invention belongs to the technical field of diesel-methanol dual-fuel engines, and in particular relates to a method and system for controlling methanol injection timing of a diesel-methanol dual-fuel engine. Background Art

[0002] In recent years, new energy engines, especially diesel-natural gas dual-fuel engines and diesel-methanol dual-fuel engines, have gradually replaced old diesel engines. Methanol dual-fuel engines are the most prominent. Since methanol is a renewable resource and the emissions after methanol combustion do not pollute the atmosphere, the application of methanol will gradually become widely popular.

[0003] At present, the mixed combustion of diesel and methanol is still in its infancy. After methanol gas is mixed with air to participate in the combustion of diesel, the mixing ratio is still an uncertain factor, which requires each OEM to explore and test. In this context, the control method of methanol injection timing has become a key technical means for methanol combustion.

[0004] The difference in methanol injection timing seriously affects the combustion of methanol after mixing with air. If the control timing is disordered, the methanol will not be able to burn and will also cause the risk of host flameout and methanol leakage.

[0005] Through the above analysis, the problems and defects of the existing technology are: the existing technology cannot accurately control the injection time of methanol, cannot make methanol be injected at the best time, and cannot accurately enter the cylinder for combustion. Summary of the invention

[0006] In order to overcome the problems existing in the related art, the disclosed embodiment of the present invention provides a method and system for controlling the methanol injection timing of a diesel-methanol dual-fuel engine, and specifically relates to a method for controlling the methanol injection timing of a four-stroke diesel-methanol dual-fuel engine.

[0007] The technical solution is as follows: A method for controlling the methanol injection timing of a diesel-methanol dual-fuel engine comprises:

[0008] S1, find the top dead center of cylinder 1 through the crankshaft phase sensor and camshaft phase sensor;

[0009] S2, find the top dead center of each cylinder through the firing sequence set by the software;

[0010] S3, taking the power top dead center as the benchmark, find the air supply top dead center and find the base point for methanol injection.

[0011] In step S1, the top dead center of cylinder 1 is found, including:

[0012] S101, judging that the crankshaft rotates one circle by a crankshaft phase sensor for a preset number of crankshaft teeth, and judging the top dead center of cylinder 1 by detecting the angle difference between a characteristic tooth on the crankshaft and the top dead center, wherein the top dead center of cylinder 1 is the air supply top dead center or the power top dead center;

[0013] S102, collecting the position of the camshaft phase sensor, determining the number of cam turns according to the physical position of the cam and the crankshaft, and setting a threshold in the software.

[0014] In step S1, through the crankshaft phase sensor and the camshaft phase sensor, including: a timing gun for displaying timing is externally connected to the alcohol injection valve, the sampled current is converted into light illumination, the current moment is reflected on the crankshaft, the scale produced by the timing gun is used as the standard, and the value is modified in the software to compensate for the angle deviation from the timing gun.

[0015] In step S2, the firing sequence set by the software is: 1-3-5-6-4-2.

[0016] In step S3, the top dead center of the air supply is found based on the power top dead center, and the base point for methanol injection is found, including: when the main engine speed is 300r / min-800r / min, the methanol injection time is the crankshaft angle 2.7°-7.5° before the exhaust valve is closed.

[0017] Furthermore, when the main engine speed is 300r / min-800r / min, the methanol injection timing is when the crankshaft angle is 3°-8° before the exhaust valve is closed.

[0018] Furthermore, according to the increasing speed of the main engine, the methanol injection timing increases linearly with the crankshaft angle before the exhaust valve closes.

[0019] Another object of the present invention is to provide a control system for the methanol injection timing of a diesel-methanol dual-fuel engine, the system implementing the control method for the methanol injection timing of the diesel-methanol dual-fuel engine, the system comprising:

[0020] The 1st cylinder power top dead center acquisition module is used to find the 1st cylinder power top dead center through the crankshaft phase sensor and the camshaft phase sensor;

[0021] The module for obtaining the top dead center of each cylinder is used to find the top dead center of each cylinder in sequence according to the firing sequence set by the software;

[0022] The methanol injection base point acquisition module is used to find the air supply top dead center based on the power top dead center, so as to find the base point for methanol injection.

[0023] Furthermore, the control system is mounted on a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the functions of the control system for the methanol injection timing of the diesel-methanol dual-fuel engine can be realized.

[0024] Another object of the present invention is to provide a storage medium for receiving user input program, the stored computer program enables the electronic device to execute the control method of the methanol injection timing of the diesel-methanol dual-fuel engine

[0025] In combination with all the above technical solutions, the beneficial effects of the present invention are as follows: the operating method of the present invention can accurately control the methanol injection time to achieve the best point for methanol to enter the cylinder and burn. The present invention accurately controls the engine air supply timing, and on this basis accurately controls the methanol injection time, so that methanol is injected at the best time, avoiding methanol wall spray or front and back spray so that methanol cannot accurately enter the cylinder and burn. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings herein are incorporated in and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the description, serve to explain the principles of the present disclosure;

[0027] Figure 1 is a flow chart of a method for controlling the methanol injection timing of a diesel-methanol dual-fuel engine provided by an embodiment of the present invention;

[0028] Figure 2 Adjust injection timing schematic for crankshaft phase sensor;

[0029] Figure 3 Adjust injection timing schematic for camshaft phase sensor;

[0030] Figure 4 In order to start the methanol injection at the appropriate angle before the exhaust valve closes, the intake valve is in the open state, the piston descends faster, and it is easier to inhale the methanol mixture into the cylinder. DETAILED DESCRIPTION

[0031] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific implementation disclosed below.

[0032] Embodiment 1, as Figure 1 As shown, the method for controlling the methanol injection timing of a diesel-methanol dual-fuel engine provided by an embodiment of the present invention includes:

[0033] S1, find the top dead center of cylinder 1 through the crankshaft phase sensor and camshaft phase sensor;

[0034] S2, find the top dead center of each cylinder through the firing sequence set by the software;

[0035] S3, taking the power top dead center as the benchmark, find the air supply top dead center and find the base point for methanol injection.

[0036] In step S1, the top dead center of cylinder 1 is found, including:

[0037] S101, judging that the crankshaft rotates one circle by a crankshaft phase sensor for a preset number of crankshaft teeth, and judging the top dead center of cylinder 1 by detecting the angle difference between a characteristic tooth on the crankshaft and the top dead center, wherein the top dead center of cylinder 1 is the air supply top dead center or the power top dead center;

[0038] S102, collecting the position of the camshaft phase sensor, determining the number of cam turns according to the physical position of the cam and the crankshaft, and setting a threshold in the software.

[0039] In step S1, through the crankshaft phase sensor and the camshaft phase sensor, including: a timing gun for displaying timing is externally connected to the alcohol injection valve, the sampled current is converted into light illumination, the current moment is reflected on the crankshaft, the scale produced by the timing gun is used as the standard, and the value is modified in the software to compensate for the angle deviation from the timing gun.

[0040] In step S2, the firing sequence set by the software is: 1-3-5-6-4-2.

[0041] In step S3, the top dead center of the air supply is found based on the power top dead center, and the base point for methanol injection is found, including: when the main engine speed is 300r / min-800r / min, the methanol injection time is the crankshaft angle 2.7°-7.5° before the exhaust valve is closed.

[0042] When the main engine speed is 300r / min-800r / min, the methanol injection timing is when the crankshaft angle is 3°-8° before the exhaust valve closes.

[0043] According to the increase of main engine speed, the methanol injection timing increases linearly with the crankshaft angle before the exhaust valve closes.

[0044] Exemplarily, both the intake and exhaust valves are in an open state at the top dead center of the air supply. Therefore, it is necessary to avoid the state where the exhaust valve is open to prevent methanol gas from escaping from the exhaust valve. The crankshaft angle from the exhaust valve closing to the intake valve closing is the methanol intake stage. Therefore, in theory, the methanol valve opening time should be the exhaust valve closing time (crankshaft angle). In the initial test, the exhaust valve closing time is used as the methanol valve opening time (crankshaft angle). As the main engine speed increases, the crankshaft rotation speed becomes faster, and the frequency of opening and closing of the intake and exhaust valves becomes faster, but the methanol injection time does not change. Therefore, methanol is easy to miss the cylinder entry time at high speed. At this time, the solution is to advance the injection time of methanol. The specific time (angle) is based on the crankshaft speed. For example: when the main engine speed is 300r / min, it is 5r / s, each circle is 200ms, and each degree is 0.56ms. At this time, methanol is injected at the exhaust valve closing time. If the injection time is 1.5ms, the crankshaft rotation angle is 2.7°.

[0045] When the main engine is 600r / min, 10r / s, 100ms per revolution, 0.28ms per degree, the injection time is still 1.5ms, and the crankshaft rotates by 5.4°. It can be seen that at different speeds, when the injection time remains unchanged, the intake angle will change. Therefore, in order to make up for the angle missed at high speed, it is necessary to advance the methanol injection time at high speed. The advance time (angle) is the calculated rotation angle. Taking the above formula as an example, at 300 revolutions, it needs to be advanced by 2.7°; at 600 revolutions, it needs to be advanced by 5.4°.

[0046] The above are theoretical values. Since the crankshaft angle uses a sensor to collect the number of teeth to determine the crankshaft angular speed, the number of crankshaft teeth has a greater impact on the system. The more teeth there are, the greater the sampling frequency and the more accurate the angle control; the fewer teeth there are, the smaller the sampling frequency and the greater the angle control deviation. Therefore, during the test, it is necessary to connect an instrument used to display timing - a timing gun - to the injection valve. The timing gun converts the sampling current into light illumination, which can directly reflect the current moment on the crankshaft. The scale produced by the timing gun shall prevail, and the value shall be modified in the software to compensate for the angle deviation from the timing gun.

[0047] The above operation method can accurately control the methanol injection timing to achieve the optimal point for methanol to enter the cylinder and burn.

[0048] Example 2, as another embodiment of the present invention, the method for controlling the methanol injection timing of a diesel-methanol dual-fuel engine provided by the embodiment of the present invention includes:

[0049] Figure 2 and Figure 3 The crankshaft phase and camshaft phase sensors collect angles to determine the top dead center of cylinder 1 and provide a reference value for the top dead center of the air supply. Based on this, the injection timing is adjusted to achieve precise control.

[0050] Through the above Figure 2 Crankshaft phase sensor and Figure 3 Camshaft phase sensor, the system first determines the crankshaft rotation of one circle by the preset number of crankshaft teeth in the system, and then determines the top dead center of a cylinder (air supply top dead center or power top dead center) by detecting the angle difference between the characteristic teeth on the crankshaft and the top dead center (system preset); then the system collects the position of the camshaft phase sensor, and determines whether the cam is the first or second circle according to the physical position of the cam and the crankshaft. The threshold can be set in the software. Through the above process, the phase (1 cylinder power top dead center) can be accurately found. Then, through the ignition sequence set by the software (1-3-5-6-4-2), the power top dead center of each cylinder is found in sequence. Secondly, push forward 360 degrees based on the power top dead center to find the air supply top dead center and find the base point for methanol injection. In the initial test, the exhaust valve closing time is used as the methanol valve opening time (crankshaft angle). As the main engine speed increases, the crankshaft rotation speed becomes faster, and the opening and closing frequency of the intake and exhaust valves becomes faster, but the methanol injection time does not change, so methanol is easy to miss the cylinder entry time at high speeds. The solution at this time is to advance the time of alcohol spraying. Figure 4 To be specific: the methanol injection moment begins at an appropriate angle before the exhaust valve closes (see the next paragraph for detailed methods). At this time, the intake valve is in an open state, and the piston descends at a faster rate, making it easier to inhale the methanol mixture into the cylinder; the exhaust valve is about to close, and the exhaust valve is closed during the process from methanol injection to methanol entry, which can prevent methanol gas from being discharged.

[0051] The specific time (angle) is based on the crankshaft rotation speed, as shown in the following example:

[0052] When the host speed is 300r / min, the host speed is converted to 5r / s, each circle is 200ms, each circle is 360°, then each degree is 200ms / 360°=0.56ms, at this time, methanol is injected when the exhaust valve is closed. Actual tests have verified that the opening time of the methanol injector is 1.5ms (physical properties of the methanol injector), then the crankshaft rotates an angle of 1.5ms / 0.56ms=2.7° during the opening process of the methanol injector.

[0053] When the host speed is 800r / min, the host speed is converted to 13.3r / s, each circle is 75ms, and each degree of 360° per circle is 75ms / 360°=0.2ms. At this time, the injection time is still 1.5ms. During the process of opening the alcohol injector, the crankshaft rotates by an angle of 1.5ms / 0.2ms=7.5°.

[0054] Therefore, taking the main engine speed of 300r / min-800r / min as an example, the methanol injection timing should be 2.7°-7.5° before the exhaust valve closes, which is about 3°-8° crankshaft angle (the shaded part in the figure) as the optimal injection timing, and increases linearly with the increasing speed.

[0055] Embodiment 3, the embodiment of the present invention provides a control system for methanol injection timing of a diesel-methanol dual-fuel engine, the system comprising:

[0056] The 1st cylinder power top dead center acquisition module is used to find the 1st cylinder power top dead center through the crankshaft phase sensor and the camshaft phase sensor;

[0057] The module for obtaining the top dead center of each cylinder is used to find the top dead center of each cylinder in sequence according to the firing sequence set by the software;

[0058] The methanol injection base point acquisition module is used to find the air supply top dead center based on the power top dead center, so as to find the base point for methanol injection.

[0059] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0060] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principles of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for controlling the methanol injection timing of a diesel-methanol dual-fuel engine, characterized in that: The method includes: S1, find the top dead center of cylinder 1 through the crankshaft phase sensor and camshaft phase sensor; S2, find the top dead center of each cylinder through the firing sequence set by the software; S3, taking the power top dead center as the benchmark, find the air supply top dead center and find the base point for methanol injection.

2. The method for controlling the methanol injection timing of a diesel-methanol dual-fuel engine according to claim 1, characterized in that: In step S1, the top dead center of cylinder 1 is found, including: S101, judging that the crankshaft rotates one circle by a crankshaft phase sensor for a preset number of crankshaft teeth, and judging the top dead center of cylinder 1 by detecting the angle difference between a characteristic tooth on the crankshaft and the top dead center, wherein the top dead center of cylinder 1 is the air supply top dead center or the power top dead center; S102, collecting the position of the camshaft phase sensor, determining the number of cam turns according to the physical position of the cam and the crankshaft, and setting a threshold in the software.

3. The method for controlling the methanol injection timing of a diesel-methanol dual-fuel engine according to claim 1, characterized in that: In step S1, through the crankshaft phase sensor and the camshaft phase sensor, including: a timing gun for displaying timing is externally connected to the alcohol injection valve, the sampled current is converted into light illumination, the current moment is reflected on the crankshaft, the scale produced by the timing gun is used as the standard, and the value is modified in the software to compensate for the angle deviation from the timing gun.

4. The method for controlling the methanol injection timing of a diesel-methanol dual-fuel engine according to claim 1, characterized in that: In step S2, the firing sequence set by the software is: 1-3-5-6-4-2.

5. The method for controlling the methanol injection timing of a diesel-methanol dual-fuel engine according to claim 1, characterized in that: In step S3, the top dead center of the air supply is found based on the power top dead center, and the base point for methanol injection is found, including: when the main engine speed is 300r / min-800r / min, the methanol injection time is the crankshaft angle 2.7°-7.5° before the exhaust valve is closed.

6. The method for controlling the methanol injection timing of a diesel-methanol dual-fuel engine according to claim 5, characterized in that: When the main engine speed is 300r / min-800r / min, the methanol injection timing is when the crankshaft angle is 3°-8° before the exhaust valve closes.

7. The method for controlling the methanol injection timing of a diesel-methanol dual-fuel engine according to claim 6, characterized in that: According to the increase of main engine speed, the methanol injection timing increases linearly with the crankshaft angle before the exhaust valve closes.

8. A control system for methanol injection timing of a diesel-methanol dual-fuel engine, characterized in that: The system implements the method for controlling the methanol injection timing of a diesel-methanol dual-fuel engine as claimed in any one of claims 1 to 7, and the system comprises: The 1st cylinder power top dead center acquisition module is used to find the 1st cylinder power top dead center through the crankshaft phase sensor and the camshaft phase sensor; The module for obtaining the top dead center of each cylinder is used to find the top dead center of each cylinder in sequence according to the firing sequence set by the software; The methanol injection base point acquisition module is used to find the air supply top dead center based on the power top dead center, so as to find the base point for methanol injection.

9. The control system for methanol injection timing of a diesel-methanol dual-fuel engine according to claim 8, characterized in that: The system is mounted on a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the functions of the control system of the methanol injection timing of the diesel-methanol dual-fuel engine can be realized.

10. A program storage medium for receiving user input, characterized in that: The stored computer program enables the electronic device to execute the method for controlling the methanol injection timing of a diesel-methanol dual-fuel engine as described in any one of claims 1-7.