Engine intake injection system and control method

Abstract

An engine intake injection system is provided, including a methanol injection system, an intake system and a high-temperature water bypass system. The methanol injection system includes a methanol injection valve and a mixer. The methanol injection valve is used to inject methanol into the mixer. The mixer is connected to the engine cylinder through an intake duct. The intake system includes a supercharger and a main intake pipeline and an auxiliary intake pipeline connected to the outlet of the supercharger. The main intake pipeline includes an air cooler. The auxiliary intake pipeline is connected to the mixer to form a heating pipeline for sending high-pressure and high-temperature air into the mixer to supply the heat required for vaporization of methanol. The high-temperature water bypass system is used to heat the mixer. The high-temperature water bypass system and the heating pipeline are configured to be able to be opened simultaneously or selectively. The above system can preferably provide heat for methanol vaporization. An engine intake injection control method is also provided.

Description

Technical Field

[0001] The present invention relates to the field of engines, in particular to the field of methanol fuel engines. Background Art

[0002] In the context of carbon neutrality, methanol is considered to be one of the main alternative fuels to fuel oil. It has the characteristics of high octane number and large latent heat of vaporization. Methanol fuel has a high octane number and a high auto-ignition temperature. It is difficult to achieve in-cylinder combustion through direct compression ignition, and usually requires ignition combustion. There are roughly two ways for methanol to enter the cylinder: one is that methanol is injected through the intake duct and enters the cylinder with the air, and the other is that methanol is directly injected into the cylinder at high pressure.

[0003] Since methanol has a large latent heat of vaporization, it takes a long time and enough heat to achieve full atomization. When liquid methanol is injected into the cylinder intake duct, methanol will absorb more heat when it changes from liquid to gas, which will reduce the intake duct temperature. The cooled intake duct will affect the subsequent methanol vaporization during injection, resulting in the inability of liquid methanol to completely change to gas when methanol is injected into the intake duct. Some liquid methanol will enter the cylinder with the air. If the methanol droplets in the cylinder have not vaporized when they touch the cylinder wall, they will adhere to the combustion chamber and the cylinder liner wall in liquid form, diluting the lubricating oil stored in the cylinder liner mesh, which is very likely to cause wear and cylinder scuffing. At the same time, the methanol attached to the combustion chamber will also enter the lubricating oil with the movement of the piston, causing the lubricating oil to emulsify. For this reason, it is necessary to control the intake temperature after supercharging, control the liquid methanol to complete the vaporization before touching the cylinder wall, and reduce the risk of cylinder scuffing and lubricating oil emulsification. Summary of the invention

[0004] An object of the present invention is to provide an engine intake injection system that can achieve a better methanol vaporization effect.

[0005] To achieve the above-mentioned purpose, the engine intake injection system includes a methanol injection system, an intake system and a high-temperature water bypass system. The methanol injection system includes a methanol injection valve and a mixer. The methanol injection valve is used to inject methanol into the mixer. The mixer is connected to the engine cylinder through an intake duct; the intake system includes a supercharger and a main intake pipeline and an auxiliary intake pipeline connected to the outlet of the supercharger. The main intake pipeline includes an air cooler. The auxiliary intake pipeline is connected to the mixer to form a heating pipeline for delivering high-pressure and high-temperature air into the mixer to supply the methanol with the heat required for vaporization; the high-temperature water bypass system is used to heat the mixer; wherein the high-temperature water bypass system and the heating pipeline are configured to be able to be opened simultaneously or selectively.

[0006] In one or more embodiments, the main air intake pipeline also includes an auxiliary heat intake pipeline, which is connected to the auxiliary air intake pipeline and is used to supply cooling gas to the heating pipeline for temperature adjustment. The air intake system also includes a boost air electric control valve arranged on the heating pipeline and used to connect the auxiliary heat intake pipeline and the auxiliary air intake pipeline.

[0007] In one or more embodiments, the high-temperature water bypass system further includes a high-temperature water electric control valve for regulating the flow in the high-temperature water bypass system.

[0008] In one or more embodiments, simultaneous opening or selective opening of the high-temperature water bypass system and the heating pipeline is determined by an engine operation mode, and the engine operation mode includes a diesel mode and a methanol dual-fuel mode.

[0009] In one or more embodiments, the engine intake injection system also includes a control system and a temperature detection system, wherein the temperature detection system is used to detect the temperature in the heating pipeline and / or the high-temperature water bypass system, and the control system is used to receive the measurement value signal of the temperature detection system and send a signal to adjust the flow and / or temperature of the heating pipeline and / or the high-temperature water bypass system.

[0010] In one or more embodiments, the air intake duct is a venturi tube, a passage for introducing a methanol-air mixture is provided at a throat of the air intake duct with the smallest diameter, and an inlet end of the air intake duct is used for introducing air.

[0011] Another object of the present invention is to provide an engine intake injection control method, comprising the following steps: determining the operating mode of the engine; when the engine is operating in diesel mode, stopping the high-temperature water bypass system from heating the mixer, stopping the intake of the auxiliary intake pipe and allowing all the air to be air-cooled through the main intake pipe and then sent into the cylinder; when the engine is operating in methanol dual-fuel mode, determining the amount of heat supplied by the high-temperature water bypass system to the mixer based on the working parameters in the cylinder, and adjusting the air temperature in the heating pipe based on whether the air temperature in the mixer meets the methanol vaporization requirements.

[0012] In one or more embodiments, when the maximum flow rate and the maximum temperature of the air supplied by the heating pipeline cannot meet the vaporization requirements, the methanol substitution rate in the dual-fuel mode of the engine is reduced.

[0013] In one or more embodiments, when the engine is running at different loads, the required air temperature of the heating pipeline and / or the water supply heat of the high-temperature water bypass system are determined according to parameters such as engine speed, load, supercharger speed, intake pressure and the control curve of the electronically controlled valve, and then the air heat in the heating pipeline and / or the water supply heat of the high-temperature water bypass system are adjusted.

[0014] In one or more embodiments, the engine operates in diesel mode when the engine is cold, and switches to methanol dual-fuel mode after warming up.

[0015] The above engine intake injection system introduces a portion of high-temperature air from behind the supercharger to provide vaporization heat for methanol, and then injects methanol into the air in the heating pipe, making full use of the heat after air supercharging, and preventing the overall intake temperature from rising, and not affecting the cylinder filling coefficient due to the increase in intake temperature. This small portion of air introduced from behind the supercharger can also be controlled at a suitable temperature and flow rate according to the methanol injection amount under different working conditions, achieving the purpose of methanol vaporization with less high-temperature air. In addition, a high-temperature water bypass system is provided, so that the high-temperature gas and high-temperature water heating schemes can be flexibly selected to provide suitable heat for methanol vaporization. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other features, properties and advantages of the present invention will become more apparent through the following description in conjunction with the accompanying drawings and embodiments, in which:

[0017] Figure 1 is a schematic diagram of an embodiment of an engine intake injection system;

[0018] Figure 2 is a schematic diagram of the principle of an embodiment that only uses a high-temperature water bypass system for heating;

[0019] Figure 3 It is a schematic diagram of the structure of the Venturi tube inlet;

[0020] Figure 4 is a simplified flow chart of one embodiment of an engine intake injection control method;

[0021] Figure 5 It is a specific flow chart of an embodiment of an engine intake injection control method.

[0022] Symbols and Markings

[0023] 1 Supercharger

[0024] 2 Air Cooler

[0025] 3 Cylinders

[0026] 4 Methanol injection valve

[0027] 5. Mixer

[0028] 6 Electric boost air valve

[0029] 7 Temperature Sensor

[0030] 10 High temperature water electric control valve

[0031] 13 Intake system

[0032] 14 High temperature water bypass system

[0033] 31 Main air intake line

[0034] 32 Auxiliary air intake line

[0035] 35 Heating pipeline

[0036] 40 Intake

[0037] 41 Throat

[0038] 42 channels

[0039] 401 High temperature water inlet

[0040] 404 High temperature water outlet

[0041] 501 Air Inlet

[0042] 502 Methanol Import

[0043] 503 Gas outlet

[0044] 312 Auxiliary heat pipe DETAILED DESCRIPTION

[0045] The present invention is further described below in conjunction with specific embodiments and drawings. More details are elaborated in the following description to facilitate a full understanding of the present invention. However, the present invention can obviously be implemented in a variety of other ways different from the description herein. Those skilled in the art can make similar generalizations and deductions based on actual application situations without violating the connotation of the present invention. Therefore, the protection scope of the present invention should not be limited by the content of this specific embodiment.

[0046] It should be noted that these and other subsequent drawings are only examples and are not drawn to scale, and should not be used to limit the actual scope of protection required by the present invention.

[0047] Air enters the supercharger 1 from the air inlet 501. After being pressurized by the supercharger 1, the air pressure and temperature increase. In a conventional engine, the air pressurized by the supercharger 1 continues to pass through the air cooler 2, and the pressurized air is cooled to a suitable temperature range before being sent to the cylinder 3. The low-pressure intake port injection methanol engine installs the methanol injection valve 4 on the intake port of each cylinder, and each cylinder is equipped with a methanol injection valve 4 to control the methanol injection amount separately. Liquid methanol enters the methanol injection valve 4 from the methanol inlet 502, and after being sprayed into the intake port, it enters the cylinder 3 together with the pressurized and cooled air. In the process of entering the cylinder 3, the liquid methanol absorbs heat and vaporizes to become a gas, forming a mixed gas with the air, and is ignited by diesel or a spark plug to complete combustion and work, and the exhaust gas is discharged through the gas outlet 503.

[0048] Since methanol has a large latent heat of vaporization, it takes a long time and sufficient heat to achieve full atomization. If methanol cannot be completely converted into gas, it may cause problems such as liquid adhesion, wear and tear, cylinder scuffing, and lubricant emulsification.

[0049] Most of the existing technologies achieve the purpose of methanol vaporization in the intake duct by increasing the intake temperature, such as controlling the intake temperature by controlling the cooling water flow of the air cooler, and another is to use the EGR system and combine the supercharged but uncooled air to enter the intake box to control the temperature. The engine intake injection system disclosed in the present invention promotes the vaporization of methanol by introducing a high-pressure hot air treated by a high-pressure device.

[0050] like Figure 1 As shown, the engine intake injection system includes a methanol injection system, an intake system 13 and a high-temperature water bypass system 14. The methanol injection system includes a methanol injection valve 4 and a mixer 5. The methanol injection valve 4 is used to inject methanol into the mixer 5. The mixer 5 is connected to the engine cylinder 3 through the intake duct. The engine may include multiple cylinders, and each cylinder is connected to each mixer through the intake duct.

[0051] The high-temperature water bypass system is used to heat the mixer 5. After the high-temperature water flows in from the high-temperature water inlet 401, it flows through the cylinder unit and the temperature rises to 80-90°C. The bypass high-temperature water after the high-temperature water branch is used to heat the mixer 5, which can increase the wall temperature of the mixer 5 and promote the spraying of methanol onto the wall of the mixer 5. The high-temperature water is passed into the outer wall of the methanol mixer to heat the methanol mixer. When the liquid methanol is sprayed into the injector, the heat is transferred to the liquid methanol to promote the vaporization of methanol. Finally, the high-temperature water flows out at the high-temperature water outlet 404. The high-temperature water bypass system can also include a high-temperature water electric control valve 10, which is used to regulate the flow in the high-temperature water bypass system pipeline, and then adjust the heat supply to the mixer 5.

[0052] The air intake system 13 includes a supercharger 1 and a main air intake pipeline 31 and an auxiliary air intake pipeline 32 connected to the outlet of the supercharger 1. The main air intake pipeline 31 includes an air cooler 2 to cool the high-temperature air. The auxiliary air intake pipeline 32 is connected to the mixer 5 to form a heat supply pipeline 35 for sending high-pressure and high-temperature air into the mixer 5 to supply the heat required for vaporization of methanol.

[0053] That is, after the air enters the supercharger 1 from the air inlet 501, it is divided into two paths, wherein the main intake line 31 is the main path with a larger flow rate, and the air enters the cylinder after being cooled by the air cooler 2; the auxiliary intake line 32 is the auxiliary path, and the air that has not been cooled by the air cooler is sent to the methanol injection mixer 5 of each cylinder.

[0054] In some embodiments, the main air intake pipeline 31 further includes an auxiliary heat intake pipeline 312, which is in communication with the auxiliary air intake pipeline 32 and is used to supply cooling gas to the heating pipeline 35 for temperature adjustment. The air intake system 13 further includes a charge air electric control valve 6 disposed on the heating pipeline and used to connect the auxiliary heat intake pipeline 312 and the auxiliary air intake pipeline 32. The charge air electric control valve 6 may be a three-way valve, which adjusts the air temperature by adjusting the gas flow and ratio.

[0055] Specifically, Figure 1 As shown, in the case where the air is divided into two paths after the supercharger 1, the air passing through the air cooler 2 on the main intake pipeline 31 is further divided into two paths, wherein the auxiliary heat intake pipeline 312 is connected with the auxiliary intake pipeline 32 to form a heat supply pipeline 35. The heat supply pipeline 35 mixes the air that has not been cooled by the air cooler and the air that has been cooled by the air cooler to reach different temperatures required for methanol vaporization under various loads, and then sends the air into the mixer 5 to mix with methanol to promote the vaporization of methanol.

[0056] After the methanol injection valve 4 injects liquid methanol into the mixer 5, the high-temperature air sent in by the heating pipeline 35 provides heat for the vaporization of the liquid methanol. The heat of high-temperature water can also be used simultaneously or alternatively to ensure that the liquid methanol is completely vaporized in the airway and mixed with the compressed air-cooled air before entering the cylinder.

[0057] Whether the high-temperature water bypass system 14 and the heating pipeline 35 are simultaneously opened or one of them is opened is determined by the operating mode of the engine. The operating modes of the engine include diesel mode and methanol dual-fuel mode. When the engine is running in diesel mode, methanol does not enter the cylinder. In methanol dual-fuel mode, methanol and diesel enter the cylinder at the same time. After the engine is started, it is first determined whether the engine is running in diesel mode or methanol dual-fuel mode, and then the opening of the high-temperature water bypass system and the heating pipeline is determined according to different modes.

[0058] To achieve the above objectives, in some embodiments, the engine intake injection system also includes a control system and a temperature detection system. The temperature detection system is used to detect the temperature of the heating pipeline 35 and / or the high-temperature water bypass system 14. The control system is used to receive the measurement value signal of the temperature detection system and send a signal to adjust the flow and / or temperature of the heating pipeline 35 and / or the high-temperature water bypass system 14, thereby determining the amount of heat supplied to the mixer.

[0059] For example, a temperature sensor 7 is installed in the heating circuit to monitor the air temperature in the heating pipeline 35 entering the mixer 5. The temperature sensor is connected to the engine control system. According to the different temperature requirements of each load mixer, the opening of the boost air electric control valve 6 is controlled by the control system to adjust the intake air flow and / or proportion before and after air cooling, so as to achieve temperature control under various loads, and achieve different gas temperatures in the heating pipeline of methanol under different working conditions, so as to better help methanol vaporization without increasing the intake air temperature. A high-temperature water electric control valve 10 is installed on the high-temperature water bypass pipeline, and the high-temperature water bypass flow can be adjusted according to the engine control system instructions, working conditions, replacement rate and other parameters. When the engine is in the diesel fuel mode, the high-temperature water bypass pipeline is closed.

[0060] By flexibly controlling the opening of each valve through the control system ECU, the air temperature of the methanol injection port of the engine can be adjusted and controlled under various loads, thereby maximizing the methanol vaporization requirements.

[0061] An embodiment of determining the opening status of the high-temperature water bypass system and the heating pipeline through different engine modes is introduced below.

[0062] When the engine runs in diesel mode, air enters the main intake pipe 31 and is directly sent to the cylinder 3 after passing through the air cooler 2. At the same time, the high-temperature water electric control valve 10 is closed, and the high-temperature water does not flow through the methanol mixer 5.

[0063] When the engine is running in methanol dual-fuel mode, first, the high-temperature water electric control valve 10 determines the bypass pipeline flow rate according to parameters such as load and substitution rate, and the high-temperature water heats the methanol mixer 5 to increase the mixer wall temperature; at the same time, the control system determines whether the air temperature in the heating pipeline meets the methanol vaporization requirement based on the temperature sensor 7. If the temperature is not reached, the opening of the electric control valve 6 is adjusted to increase the supply flow of the high-temperature gas.

[0064] In addition, according to the heat demand for methanol vaporization, it is also possible to flexibly select one of the methods of supplying hot air through the heating pipe and supplying hot water through the high-temperature water bypass system.

[0065] like Figure 2As shown, in this embodiment, the methanol injection mixer 5 is installed above the cylinder head intake passage, and the pipeline of the cylinder unit high temperature water bypass system is connected to the methanol injection mixer 5. After the high temperature water flows through the cylinder unit, the temperature rises to 80-90°C, and then the high temperature water flows to the methanol injection mixer to heat the mixer wall surface and provide sufficient heat for methanol vaporization. According to parameters such as load and substitution rate, the high temperature water electric control valve 10 determines the bypass pipeline flow rate, thereby providing the heat required by the mixer.

[0066] The above system achieves methanol vaporization by diverting a small amount of high-temperature supercharged air, which has no effect on the temperature of the air entering the cylinder. By diverting a small amount of high-temperature supercharged air from the supercharger and air cooler, liquid methanol is vaporized, so that the intake temperature of the whole machine will not rise, and the cylinder filling coefficient will not be affected by the increase in intake temperature. After the introduction of this high-temperature supercharged air, the complete vaporization of methanol under different working conditions can be controlled. The heating pipe can provide different heat under each working condition to better promote vaporization without increasing the intake temperature. The air temperature in some areas where methanol is injected is increased, providing heat for methanol vaporization, helping methanol vaporization, and reducing the methanol vaporization time, thereby ensuring that the methanol entering the cylinder is in a completely vaporized state, avoiding the problems of cylinder pulling and lubricating oil emulsification caused by methanol droplets on the wall. The above system also realizes flexible selection between high-temperature gas heating and high-temperature water heating, providing sufficient heat for methanol vaporization, and can also be adjusted in time according to different working conditions to adapt to heat requirements.

[0067] In addition, to promote the mixing effect of the gas, in some embodiments, the intake passage 40 connected to the cylinder is a venturi tube. Figure 3 As shown, during the process of the pressurized air entering the cylinder, in order to prevent the pressurized air from flowing back, the air pressure in the heating pipeline 35 is controlled so that the mixed air can smoothly enter the cylinder. The intake duct 40 of each cylinder adopts a Venturi tube structure, including an inlet end 43, a throat 41 and an outlet end 44.

[0068] The inlet end 43 of the intake duct introduces the supercharged air-cooled air, and the throat 42 of the intake duct 40 is provided with a passage 42 for introducing the methanol-air mixture at the smallest diameter, and then the methanol-air mixture is sprayed at the smallest diameter of the throat of the air duct. The cross-sectional area at the throat becomes smaller, the flow rate increases, and the pressure at this place becomes smaller. The pressure difference between the air at the throat and the methanol-air mixture promotes the mixing of the methanol-air mixture with the main circuit supercharged air under the action of the pressure difference. The above structure realizes the effect of mixed flow of air entering the cylinder at different positions, which promotes the methanol-air mixture to smoothly enter the cylinder and burn.

[0069] In combination with the above introduction to the engine intake injection system, an engine intake injection control method can also be understood.

[0070] Reference Figure 4The flowchart shown shows that, first, the operating mode of the engine is determined after the engine is started.

[0071] When the engine is running in diesel mode, the high-temperature water bypass system is stopped from supplying heat to the mixer, such as by closing the high-temperature water electric control valve 10, and the intake of the auxiliary intake line 32 is stopped so that all the air is air-cooled through the main intake line 31 and then sent into the cylinder 3.

[0072] When the engine is running in methanol dual fuel mode, the heat supply of the high temperature water bypass system to the mixer 5 is determined according to the working parameters in the cylinder such as load and substitution rate; the air temperature in the heating pipeline 35 is adjusted according to whether the air temperature in the mixer meets the methanol vaporization requirement. The adjustment is performed by the aforementioned three-way valve, which will not be described in detail here.

[0073] In some embodiments, when the maximum amount of air supplied by the heating pipe cannot meet the vaporization requirement, such as when the temperature sensor 7 still cannot reach the required temperature range when the electric control valve 6 is fully opened, the control system will reduce the methanol substitution rate. After the engine is warmed up or the load is increased, the methanol substitution rate will continue to be increased, and the opening of the boost air electric control valve 6 will be adjusted according to the control system boost air electric control valve control curve (map) to adjust the air temperature in the heating pipe 35.

[0074] Continue to refer to Figure 5 As shown, when the engine is running at different loads, such as high load or low load, the heat supply of the high-temperature water bypass system and / or the heat supply of the heating pipeline are determined according to parameters such as engine speed, load, supercharger speed, intake pressure and the high-temperature water electric control valve control curve diagram (map diagram), and then the air heat in the heating pipeline and / or the water heat of the high-temperature water bypass system are adjusted by adjusting the opening of the electric control valve.

[0075] For example, when the engine is running at high load, the required air temperature of the heating pipeline is determined according to the control curve of the boost air electric control valve (map), and then the electric control valve is controlled to adjust the air heat in the heating pipeline and / or the water heat of the high-temperature water bypass system. The temperature value output by the temperature sensor is used to determine whether the air temperature in the heating pipeline meets the control curve of the electric control valve. If it meets the requirements, the substitution rate is gradually adjusted through the control system. The substitution rate refers to the ratio of methanol to fuel combustion work, which is generally calculated according to the substitution ratio of the calorific value of the two fuels. The methanol substitution rate is adjusted to the required range on the map until it runs stably. If it does not meet the control curve of the electric control valve, it is necessary to reduce the methanol substitution rate in the engine operation mode according to the minimum vaporization temperature required for different substitution rates. Then continue to adjust the valve opening through the engine control system to adjust the air temperature in the heating pipeline until the requirements on the control curve of the electric control valve are met.

[0076] When the engine is cold, it runs in diesel mode, and after warming up, it can switch to methanol dual-fuel mode.

[0077] The present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or multiple times in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0078] Although the present invention is disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, any modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope defined by the claims of the present invention.

Claims

1. An engine intake injection system, It is characterized in that include: A methanol injection system, comprising a methanol injection valve and a mixer, wherein the methanol injection valve is used to inject methanol into the mixer, and the mixer is connected to an engine cylinder via an intake passage; An air intake system, comprising a supercharger and a main air intake pipeline and an auxiliary air intake pipeline connected to the outlet of the supercharger, wherein the main air intake pipeline comprises an air cooler, and the auxiliary air intake pipeline is connected to the mixer to form a heat supply pipeline for sending high-pressure and high-temperature air into the mixer to supply heat required for vaporization of methanol; as well as a high temperature water bypass system for heating the mixer; Among them, the high-temperature water bypass system and the heating pipeline are configured to be able to be opened simultaneously or selectively, and the simultaneous opening or selective opening is determined by the engine operation mode, and the engine operation mode includes a diesel mode and a methanol dual-fuel mode; the main intake pipeline also includes an auxiliary heat intake pipeline, and the auxiliary heat intake pipeline is connected to the auxiliary intake pipeline, and is used to supply cooling gas to the heating pipeline for temperature adjustment. The intake system also includes a boost air electric control valve arranged on the heating pipeline for connecting the auxiliary heat intake pipeline and the auxiliary intake pipeline.

2. The engine intake injection system according to claim 1, It is characterized in that The high-temperature water bypass system also includes a high-temperature water electric control valve for regulating the flow in the high-temperature water bypass system.

3. The engine intake injection system as claimed in claim 1, It is characterized in that The engine intake injection system also includes a control system and a temperature detection system. The temperature detection system is used to detect the temperature in the heating pipeline and / or the high-temperature water bypass system. The control system is used to receive the measurement value signal of the temperature detection system and send a signal to adjust the flow and / or temperature of the heating pipeline and / or the high-temperature water bypass system.

4. The engine intake injection system as claimed in claim 1, It is characterized in that The air inlet is a venturi tube structure, a passage for introducing a methanol-air mixture is arranged at the smallest diameter of the throat of the air inlet, and the inlet end of the air inlet is used for introducing air.

5. An engine intake injection control method, It is characterized in that Using the engine intake injection system according to any one of claims 1 to 4, the method comprises the following steps: Determine the engine's operating mode; When the engine is running in diesel mode, the high temperature water bypass system is stopped from heating the mixer, the air intake of the auxiliary air intake line is stopped, and all the air is sent into the cylinder through the main air intake line for air cooling; When the engine is running in methanol dual-fuel mode, the heat supply of the high-temperature water bypass system to the mixer is determined according to the working parameters in the cylinder, and the air temperature in the heating pipeline is adjusted according to whether the air temperature in the mixer meets the methanol vaporization requirements.

6. The engine intake injection control method according to claim 5, It is characterized in that When the maximum flow rate and maximum temperature of the air supplied by the heating pipeline cannot meet the vaporization requirements, the methanol substitution rate in the dual-fuel mode of the engine is reduced.

7. The engine intake injection control method according to claim 6, It is characterized in that When the engine is running at different loads, the required air temperature of the heating pipeline and / or the water supply heat of the high-temperature water bypass system are determined according to parameters such as engine speed, load, supercharger speed, intake pressure and the control curve of the electronic control valve, and then the air heat in the heating pipeline and / or the water supply heat of the high-temperature water bypass system are adjusted.

8. The engine intake injection control method according to claim 6, It is characterized in that When the engine is cold, it runs in diesel mode and switches to methanol dual-fuel mode after warming up.

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