Fuel injection system, engine and engine cold start method

Abstract

The invention belongs to the technical field of engine equipment, and particularly relates to a fuel injection system, an engine and an engine cold start method. An electric heating plug is arranged on a mixing body in the fuel injection system, the heating end of the electric heating plug extends into a mixing cavity, and the electric heating plug can enable the temperature in the mixing cavity to rise so that fuel injected into the mixing cavity can be rapidly evaporated into fuel steam, atomization of the fuel and formation of the fuel steam under the low-temperature condition are promoted, and the fuel injection efficiency is improved. Fuel steam can be mixed with gas entering the mixing cavity to form mixed gas, the mixed gas passes through a crankcase of the engine body from the gas outlet and then enters an air cylinder of the engine body, ignition is conducted through a sparking plug in the engine body, and stable starting of the engine in a short time under the low-temperature environment is achieved. The problem that an engine is difficult to start under the low-temperature condition due to fuel which is not prone to volatilization, large in latent heat of vaporization and high in viscosity is effectively solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of engine equipment, and particularly relates to a fuel injection system, an engine and an engine cold starting method. BACKGROUND

[0002] The fuel injection system refers to a fuel supply device that sprays a certain amount of fuel into a cylinder or an intake port under a certain pressure by using an oil injector. According to the type of the injected fuel, the fuel injection system can be divided into a gasoline injection system, a diesel injection system and a gaseous fuel injection system, etc. According to the control mode, the fuel injection system can be divided into a mechanical control type, an electronic control type and a mechanical-electronic hybrid control type.

[0003] At present, the commonly used fuels for engines include gasoline, diesel and kerosene, etc. Some of the fuels (diesel and kerosene, etc.) have the characteristics of not being easy to volatilize, having large latent heat of vaporization and large viscosity. Under low temperature conditions, the fuel atomization effect is poor, which causes the mixture gas (a gas formed by mixing fuel and air) to be too lean, which is not conducive to the cold starting of the engine, resulting in the difficulty of the cold starting of the engine. SUMMARY

[0004] The present application provides a fuel injection system, an engine and an engine cold starting method to solve the technical problem that some fuels are not conducive to the cold starting of the engine due to their characteristics, resulting in the difficulty of the cold starting of the engine in the prior art.

[0005] The present application is implemented by the following technical scheme:

[0006] The fuel injection system comprises a mixing body, an oil nozzle and an electric heating plug.

[0007] The mixing body is internally provided with a mixing chamber, and the mixing body is provided with a gas inlet and a gas outlet which are in communication with the mixing chamber.

[0008] The electric heating plug is arranged on the mixing body, and a heating end of the electric heating plug extends into the mixing chamber.

[0009] The oil nozzle is arranged on the mixing body and is used for injecting fuel into the mixing chamber. The electric heating plug can increase the temperature in the mixing chamber, so that the fuel entering the mixing chamber is evaporated into fuel vapor. After the fuel vapor mixes with the gas entering the mixing chamber to form a mixture gas, the mixture gas enters the cylinder of the engine body through the crankcase of the engine body.

[0010] In order to better implement the present application, the fuel injection system further comprises a first temperature sensor in the above structure.

[0011] The first temperature sensor is arranged on the mixing body, and a working end of the first temperature sensor is located in the mixing chamber and is used for monitoring the temperature in the mixing chamber.

[0012] Meanwhile, the application also provides an engine, which comprises an engine body, an electronic control unit and the fuel injection system mentioned above.

[0013] The gas inlet is communicated with the gas outlet of an air inlet pipe in the engine body, and the gas outlet is communicated with the crankcase of the engine body.

[0014] The glow plug, the fuel nozzle and the starter motor in the engine body are all signal connected with the electronic control unit.

[0015] In order to better realize the application, the engine body is provided with a gas taking hole communicated with the cylinder, and the gas taking hole is communicated with the mixing chamber through a gas guide pipe.

[0016] In order to better realize the application, the engine further comprises a second temperature sensor for monitoring the ambient temperature.

[0017] The second temperature sensor is signal connected with the electronic control unit.

[0018] In addition, the application also provides an engine cold starting method based on the engine mentioned above, which comprises the following steps.

[0019] Starting the glow plug, and using the glow plug to make the temperature in the mixing chamber reach a preset temperature;

[0020] Spraying fuel into the mixing chamber through the fuel nozzle, and evaporating the fuel into fuel vapor in the mixing chamber;

[0021] After the fuel vapor mixes with the gas entering the mixing chamber to form mixed gas, the mixed gas enters the cylinder of the engine body through the gas outlet, the crankcase of the engine body and then the cylinder of the engine body;

[0022] Igniting through the spark plug in the engine body.

[0023] In order to better realize the application, the method mentioned above is further optimized, and the preset temperature is obtained by the following way.

[0024] ;

[0025] In the formula, T 1min is the preset temperature; T 2min is the actual temperature of the mixed gas when the piston moves to the compression end point; is the compression ratio of the cylinder, and γ is the specific heat capacity ratio of the mixed gas; wherein, T 2min ≥ the lowest temperature at which the engine can be stably ignited after the spark plug ignites.

[0026] In order to better realize the present application, further optimization is made in the above method, and the temperature in the mixing chamber is brought to the preset temperature by the following method using the glow plug:

[0027] Determination of the preset temperature;

[0028] Calculation of the glow plug power:

[0029] ;

[0030] ;

[0031] ;

[0032] wherein P 电热塞 is the heating power of the glow plug; Q 电热塞 is the heat released by the glow plug; C 燃油 is the specific heat capacity of the fuel; m 燃油 is the total amount of fuel injected into the mixing chamber, is the temperature rise of the fuel; C 气体 is the specific heat capacity of the air; m 气体 is the intake air amount; is the temperature rise of the gas entering the cylinder; T 1min is the preset temperature; T 0燃油 is the initial temperature of the fuel; T 0气体 is the initial temperature of the gas entering the cylinder.

[0033] In order to better realize the present application, further optimization is made in the above method, and the temperature in the mixing chamber is brought to the preset temperature by the following method using the glow plug:

[0034] After the preset temperature is determined, the amount of fuel required for one working cycle is confirmed;

[0035] wherein the amount of fuel required for one working cycle is obtained according to the following method:

[0036] Determination of the target air-fuel ratio:

[0037] ;

[0038] wherein n0 is the required amount of oxygen obtained according to the fuel combustion reaction formula; m0 is the molar mass of the mixed gas; is the concentration of oxygen in the mixed gas; m 燃油 is the molar mass of the fuel;

[0039] According to the ideal gas state equation, the mass m a of the gas sucked in during the intake stage is calculated:

[0040] ;

[0041] P1: the pressure of the piston at the beginning of compression; V s : the displacement of the cylinder; : the volumetric efficiency; R: the gas constant of the gas;

[0042] The evaporation amount of the fuel required for one working cycle is calculated as follows:

[0043] ;

[0044] The evaporation amount of the fuel required for one working cycle is calculated as follows:

[0045] m = m f / K;

[0046] K: the evaporation coefficient of the fuel at T 1min ; m: the evaporation amount of the fuel required for one working cycle.

[0047] Compared with the prior art, the present application has the following beneficial effects:

[0048] In the fuel injection system provided by the present application, the glow plug in the mixing body can increase the temperature in the mixing chamber, so that the fuel injected into the mixing chamber can be rapidly evaporated into fuel vapor, which promotes the atomization of the fuel and the formation of the fuel vapor under low temperature conditions. The fuel vapor can be mixed with the gas entering the mixing chamber to form mixed gas, which enters the cylinder of the engine body through the gas outlet, the crankcase of the engine body, and is ignited by the spark plug in the engine body, so that the engine can be started stably in a short time under low temperature conditions, and the problem that the fuel with large latent heat of vaporization and large viscosity is difficult to start under low temperature conditions is effectively solved.

[0049] In the engine provided by the present application, the fuel injection system does not need to be provided with an additional gas source, i.e., a gas source for providing gas with pressure into the mixing chamber, and the high-pressure gas in the cylinder can directly enter the mixing chamber through the gas taking hole and the gas guide pipe, which can greatly improve the uniformity of the mixed gas and promote the atomization of the fuel, thereby improving the probability of cold start of the engine. BRIEF DESCRIPTION OF DRAWINGS

[0050] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0051] Figure 1 is a structural schematic diagram of a fuel injection system of the present application.

[0052] Figure 2 is a sectional view of a fuel injection system of the present application.

[0053] Figure 3 is a partial structural diagram of an engine of the present application.

[0054] Figure 4 is a flow chart of a cold start method of an engine of the present application.

[0055] in the figure:

[0056] 1, mixing body; 11, gas inlet; 12, gas outlet;

[0057] 2, fuel injection nozzle;

[0058] 3, glow plug;

[0059] 4, engine body; 41, gas extraction hole. DETAILED DESCRIPTION

[0060] In order to make the purpose, technical scheme and advantages of the present application more clear, the technical scheme of the present application will be described in detail below. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts fall within the scope of protection of the present application.

[0061] In the description of the present application, it should be noted that, unless otherwise specified, the meaning of "multiple" is two or more; the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" and the like are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0062] In the description of the present application, it should also be noted that, unless otherwise specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0063] In the embodiments of the present application, as shown in Figure 1 and Figure 2 , the fuel injection system comprises a mixing body 1, a fuel nozzle 2 and an electric heating plug 3; wherein,

[0064] The mixing body 1 is internally provided with a mixing chamber, and the mixing body 1 is provided with a gas inlet 11 and a gas outlet 12 which communicate with the mixing chamber;

[0065] The electric heating plug 3 is arranged on the mixing body 1, and the heating end of the electric heating plug 3 extends into the mixing chamber;

[0066] The fuel nozzle 2 is arranged on the mixing body 1, and the fuel injection end of the fuel nozzle 2 extends into the mixing chamber for injecting fuel into the mixing chamber, as shown in Figure 1 and Figure 2 .

[0067] The fuel injection system is installed on an engine body 4, and the gas inlet 11 communicates with the gas outlet of the intake pipe in the engine body 4, the gas outlet 12 communicates with the crankcase of the engine body 4, and the fuel nozzle 2 is signal connected with the electronic control unit of the engine;

[0068] When the cold start of the engine is performed, the staff can turn on the power switch of the electric heating plug 3 to gradually increase the temperature thereof, so as to increase the temperature in the mixing chamber;

[0069] Subsequently, the starting motor of the engine drives the crankshaft to rotate; at the same time, the electronic control unit controls the fuel nozzle 2 to open, and injects fuel into the mixing chamber through the fuel nozzle 2; the fuel is rapidly evaporated into fuel vapor when entering the mixing chamber due to the high temperature, and the fuel vapor mixes with the gas (air) entering the mixing chamber to form mixed gas, which is then introduced into the cylinder of the engine body 4 through the crankcase of the engine body 4 and the gas outlet 12;

[0070] The electronic control unit controls the spark plug of the engine to ignite, so that the engine is normally started; after the engine idling is stable, the electric heating plug 3 can be turned off, and the cold start of the engine is completed.

[0071] The electric heating plug 3 arranged on the mixing body 1 can promote the atomization of the fuel and the formation of the fuel vapor under low temperature conditions, and the mixing efficiency of the fuel vapor and the air (gas-gas) is much higher than that of the fuel and the air (liquid-gas), which promotes the formation of homogeneous mixed gas, realizes the stable start of the engine under low temperature conditions in a short time, and effectively solves the problem that the fuel which is not easy to evaporate, has large latent heat of vaporization and large viscosity causes the engine to be difficult to start under low temperature conditions.

[0072] It is worth noting that the cold start of the engine (cold start) refers to the start process after a certain time from the last shutdown under the condition that the temperature of the engine body (engine body 4) is consistent with the ambient temperature. In this process, the poor atomization effect of low-temperature fuel causes the mixture to be too lean, resulting in difficulty in cold start of the engine. The fuel injection system provided in the embodiment can improve the temperature in the mixing chamber by the glow plug 3, so that the fuel entering the mixing chamber can be quickly evaporated into fuel vapor, promoting the formation of homogeneous mixture, to solve the problem of cold start of the engine.

[0073] In some embodiments, the fuel injection system further comprises a first temperature sensor; wherein,

[0074] The first temperature sensor is arranged on the mixing body 1, and the working end of the first temperature sensor is located in the mixing chamber for monitoring the temperature in the mixing chamber.

[0075] When the temperature in the mixing chamber reaches a temperature sufficient to evaporate the fuel, the electronic control unit controls the fuel injector 2 to start working to inject fuel into the mixing chamber, so that the fuel can be quickly evaporated into fuel vapor when entering the mixing chamber, to promote the atomization of the fuel and the formation of fuel vapor under low-temperature conditions.

[0076] Based on the above-mentioned fuel injection system, the embodiment further provides an engine, which comprises an engine body 4, an electronic control unit and the above-mentioned fuel injection system, as shown in Figures 1 to 3 ; wherein,

[0077] The gas inlet 11 is in communication with the gas outlet of the intake pipe in the engine body 4, and the gas outlet 12 is in communication with the crankcase of the engine body 4.

[0078] The glow plug 3, the fuel injector 2 and the starter motor in the engine body 4 are signal connected with the electronic control unit.

[0079] When the cold start of the engine is performed, the worker can turn on the power switch of the glow plug 3 through the electronic control unit, so that the temperature of the glow plug 3 gradually rises to increase the temperature in the mixing chamber.

[0080] Subsequently, the electronic control unit controls the starter motor of the engine to start working to drive the flywheel in the engine body 4 to rotate; at the same time, the electronic control unit controls the fuel injector 2 to open to inject fuel into the mixing chamber through the fuel injector 2; the fuel will quickly evaporate into fuel vapor when entering the mixing chamber, and the fuel vapor and the air entering the mixing chamber are mixed to form a mixture, which is then introduced into the cylinder of the engine body 4 through the crankcase of the engine body 4 and the gas outlet 12.

[0081] At this time, the electronic control unit will control the spark plug of the engine to ignite, so that the engine starts normally; after the engine idling is stable, the electronic control unit will automatically turn off the glow plug 3, and the cold start of the engine is completed.

[0082] In some embodiments, the engine body 4 is provided with a gas taking hole 41 communicating with the cylinder, see Figure 3 The gas taking hole 41 communicates with the mixing chamber through a gas guide pipe (not shown in the figure);

[0083] When the fuel enters the mixing chamber and evaporates into fuel vapor, the piston in the engine body 4 is in the compression stage, so that the gas in the cylinder becomes high pressure gas, part of the high pressure gas enters the mixing chamber through the gas guide pipe, mixes with air and fuel vapor in the mixing chamber to form mixed gas, and then enters the cylinder of the engine body 4 through the crankcase of the engine body 4;

[0084] The part of the high pressure gas entering the mixing chamber from the cylinder can disperse the fuel vapor in the mixing chamber to promote the atomization of the fuel and improve the cold start probability of the engine.

[0085] In addition, after the engine starts successfully, the heat provided by the part of the high pressure gas entering the mixing chamber from the cylinder can heat the fuel in the mixing chamber to replace the work of the glow plug 3, at this time, the glow plug 3 can be turned off to reduce the consumption of electric energy.

[0086] In some embodiments, the engine further comprises a second temperature sensor for monitoring the ambient temperature;

[0087] The second temperature sensor is signal connected with the electronic control unit, and the second temperature sensor is used for monitoring the temperature of the environment;

[0088] During the cold start process, the electronic control unit can obtain the temperature of the environment through the second temperature sensor, that is, the temperature of the air entering the mixing chamber can be obtained, and based on the temperature information (information of the temperature of the air entering the mixing chamber), the minimum heating power of the glow plug 3 (the minimum temperature at which the engine can be stably ignited after the mixed gas is heated to the ignition temperature of the spark plug) can be calculated, and the consumption of electric energy (required by the glow plug 3) is reduced.

[0089] Based on the above-mentioned engine, the embodiment also provides an engine cold start method, see Figure 4 The method comprises the following steps:

[0090] Start the glow plug 3, and heat the temperature in the mixing chamber to a preset temperature by using the glow plug 3;

[0091] Inject fuel into the mixing chamber through the fuel nozzle 2, and the fuel evaporates into fuel vapor in the mixing chamber;

[0092] The fuel vapor mixes with the gas (air and high pressure gas) entering the mixing chamber to form a mixed gas, which then enters the cylinder of the engine body 4 through the gas outlet 12 and the crankcase of the engine body 4;

[0093] Ignition is performed by the spark plug in the engine body 4.

[0094] Specifically, the preset temperature described above is obtained as follows:

[0095] ;

[0096] In the formula, T 1min is the preset temperature (actual temperature of the mixed gas when the piston is at the compression start point); T 2min is the actual temperature of the mixed gas when the piston moves to the compression end point; is the compression ratio of the cylinder, and γ is the specific heat capacity ratio of the mixed gas; wherein, T 2min is the minimum temperature at which the engine can be stably ignited after the spark plug ignites.

[0097] It is worth noting that the compression process of the engine can be approximated as a reversible adiabatic process (ignoring heat loss), which follows the ideal gas adiabatic process equation:

[0098] ;

[0099] In the formula: T1 is the ideal temperature of the mixed gas when the piston is at the compression start point; T2 is the ideal temperature of the mixed gas when the piston is at the compression end point; =V1 / V2 compression ratio (maximum volume of the cylinder / minimum volume); γ specific heat capacity ratio of the mixed gas;

[0100] From the above formula, we can get:

[0101] ;

[0102] At this time, as long as T2 is higher than the minimum temperature at which the engine can be stably ignited after the spark plug ignites, the preliminary intake target temperature parameter (T1) is obtained;

[0103] However, the heat dissipation of the cylinder wall during the compression stage will make the actual T2 lower than the ideal value by 5%-15% or even more, which needs to be corrected through experimental measurement. The correction formula is:

[0104] T 2min =T2 / (1-η 散热 )

[0105] In the formula, T 2min is the actual temperature of the mixed gas when the piston moves to the compression end point; η 散热is the heat loss coefficient of the gas in the cylinder; therefore, the preset temperature is obtained:

[0106] .

[0107] In some embodiments, the above-mentioned use of glow plug 3 to make the temperature in the mixing chamber reach the preset temperature is performed by the following steps:

[0108] determination of the preset temperature;

[0109] calculation of the power of glow plug 3:

[0110] ;

[0111] ;

[0112] ;

[0113] wherein P 电热塞 is the heating power of glow plug 3; Q 电热塞 is the heat released by glow plug 3; C 燃油 is the specific heat capacity of fuel; m 燃油 is the total amount of fuel injected into the mixing chamber, is the temperature rise of fuel; C 气体 is the specific heat capacity of air; m 气体 is the intake air amount; is the temperature rise of the gas entering the cylinder; T 1min is the preset temperature; T 0燃油 is the initial temperature of fuel; T 0气体 is the initial temperature of the gas entering the cylinder.

[0114] In some embodiments, the use of glow plug 3 to make the temperature in the mixing chamber reach the preset temperature further comprises the following steps:

[0115] After the preset temperature is determined, the amount of fuel required for one working cycle is confirmed;

[0116] wherein the amount of fuel required for one working cycle is obtained according to the following method:

[0117] determination of the target air-fuel ratio:

[0118] ;

[0119] wherein n0 is the required amount of oxygen obtained according to the fuel combustion reaction formula; m0 is the molar mass of the mixture gas; is the concentration of oxygen in the mixture gas; m 燃油 is the molar mass of fuel;

[0120] Calculate the mass m of the gas inhaled during the intake phase using the ideal gas law. a :

[0121] ;

[0122] In the formula: P1 is the pressure when the piston is at the beginning of compression; V s Cylinder displacement; R is the inflation efficiency; R is the gas constant of the gas.

[0123] Calculate the amount of fuel evaporation required for one working cycle:

[0124] ;

[0125] The amount of fuel required for one working cycle can be calculated based on the amount of fuel evaporated in one working cycle and the evaporation coefficient.

[0126] m=m f / K;

[0127] K represents fuel in T. 1min The evaporation coefficient at time; m is the amount of fuel evaporation required for one working cycle.

[0128] By performing a cold start on the engine in the above manner, the fuel temperature is higher than its evaporation temperature, which ensures that a sufficient amount of fuel can evaporate into fuel vapor. At the same time, by controlling the fuel injection quantity through the low-temperature correction strategy of the engine electronic control unit, the demand for fuel that has not yet evaporated can be made up, so as to achieve a sufficient supply of fuel vapor and ensure that the engine can complete a cold start under low-temperature conditions.

[0129] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A fuel injection system characterised in that: The system comprises a mixing body (1), an oil nozzle (2) and an electric heating plug (3); The mixing body (1) is internally provided with a mixing chamber, and the mixing body (1) is provided with a gas inlet (11) and a gas outlet (12) which are in communication with the mixing chamber; The electric heating plug (3) is arranged on the mixing body (1), and a heating end of the electric heating plug (3) extends into the mixing chamber; The oil nozzle (2) is arranged on the mixing body (1) and is used for injecting fuel into the mixing chamber; the electric heating plug (3) can increase the temperature in the mixing chamber so that the fuel entering the mixing chamber is evaporated into fuel vapor, the fuel vapor mixes with the gas entering the mixing chamber to form mixed gas, and the mixed gas enters the cylinder of the engine body (4) through the gas outlet (12) and the crankcase of the engine body (4).

2. A fuel injection system according to claim 1, characterised in that: Further comprising a first temperature sensor; the first temperature sensor is arranged on the mixing body (1), and a working end of the first temperature sensor is located in the mixing chamber and is used for monitoring the temperature in the mixing chamber.

3. An engine characterized by: The system comprises an engine body (4), an electronic control unit and the fuel injection system of claim 1 or 2. The gas inlet (11) is in communication with the gas outlet of the intake pipe in the engine body (4), and the gas outlet (12) is in communication with the crankcase of the engine body (4). The electric heating plug (3), the oil nozzle (2) and the starter motor in the engine body (4) are all signal connected with the electronic control unit.

4. The engine of claim 3, wherein: The engine body (4) is provided with a gas taking hole (41) which is in communication with the cylinder and is in communication with the mixing chamber through a gas guide pipe.

5. The engine of claim 3, wherein: Further comprising a second temperature sensor for monitoring the ambient temperature; The second temperature sensor is signal connected with the electronic control unit.

6. An engine cold start method based on the engine of any one of claims 3 to 5, characterized by: The system comprises the following steps: Start the electric heating plug (3) and use the electric heating plug (3) to make the temperature in the mixing chamber reach a preset temperature; Inject fuel into the mixing chamber through the oil nozzle (2), and evaporate the fuel into fuel vapor in the mixing chamber; The fuel vapor mixes with the gas entering the mixing chamber to form mixed gas, and then enters the cylinder of the engine body (4) through the gas outlet (12) and the crankcase of the engine body (4); Ignite by the spark plug in the engine body (4).

7. The engine cold start method of claim 6, wherein: The preset temperature is obtained by the following method: ； In the formula, T 1min is a preset temperature; T 2min is the actual temperature of the mixture gas when the piston moves to the compression end; is the compression ratio of the cylinder, and γ is the specific heat capacity ratio of the mixture gas; wherein, T 2min is the minimum temperature at which the engine can be stably ignited after the spark plug is ignited.

8. The engine cold start method of claim 7, wherein: The temperature in the mixing chamber is raised to the preset temperature by the electric heating plug (3) by the following method: Determination of the preset temperature; Calculation of the power of the electric heating plug: ； ； ； wherein P 电热塞 is the heating power of the glow plug (3); Q 电热塞 is the heat released by the glow plug (3); C 燃油 is the specific heat capacity of the fuel; m 燃油 is the total amount of fuel injected into the mixing chamber, is the temperature increase of the fuel; C 气体 is the specific heat capacity of the air; m 气体 is the intake air mass; is the temperature increase of the gas entering the cylinder; T 1min is the preset temperature; T 0燃油 is the initial temperature of the fuel; T 0气体 is the initial temperature of the gas entering the cylinder.

9. The engine cold start method of claim 8, wherein: The temperature in the mixing chamber is raised to the preset temperature by the electric heating plug (3) by the following method: After the preset temperature is determined, the amount of fuel required for one working cycle is confirmed; The amount of fuel required for one working cycle is obtained by the following method: Determination of the target air-fuel ratio: ； wherein: n0 is the required amount of oxygen calculated from the fuel combustion reaction formula; m0 is the molar mass of the mixed gas; is the concentration of oxygen in the mixed gas; m 燃油 is the molar mass of the fuel; According to the ideal gas state equation, the mass m of the gas sucked in during the intake phase is calculated a : ； wherein: P1 is the compression start point pressure; V s is the cylinder displacement; is the charge efficiency; R is the gas constant for the gas; Calculation of the evaporation amount of fuel required for one working cycle: ； The evaporation amount of fuel required for one working cycle is calculated according to the evaporation amount of fuel required for one working cycle and the evaporation coefficient: m = m f / K; K is the evaporation coefficient of the fuel at T 1min m is the evaporation quantity of the fuel required for one working cycle.

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