CN111677592A - A control system and method for mixing gaseous methanol fuel with a single-cylinder diesel engine - Google Patents

Abstract

The invention discloses a control system and method for blending gaseous methanol fuel with a single-cylinder diesel engine. Combining with multiple parts divided by a speed-exhaust temperature map of a single-cylinder diesel engine and a power-speed map of a single-cylinder diesel engine, according to the speed and The relationship between temperature and power selects the optimal mixing ratio α _w , the methanol control unit controls the opening and closing of the electronically controlled double-opening semi-circular valve according to the collected throttle opening, exhaust temperature, rotational speed and diesel engine inlet pressure to adjust the methanol blending ratio. The invention realizes the best match between the methanol mixing ratio and the single-cylinder diesel engine operating conditions, and simultaneously takes into account the safety of the single-cylinder diesel engine mixing methanol and the power performance of the single-cylinder diesel engine mixing methanol.

Description

A control system and method for mixing gaseous methanol fuel with a single-cylinder diesel engine

technical field

The invention belongs to the field of single-cylinder diesel engines, and relates to a control system and a method for mixing gaseous methanol fuel with a single-cylinder diesel engine.

Background technique

Diesel engines have the advantages of high compression ratio, good adaptability and high thermal efficiency. They are the main power source in agriculture, transportation and other fields. However, pollutants such as NOx, HC, and PM generated by diesel engines during operation will cause air pollution. In 2019, my country's dependence on foreign oil exceeded 70%. In order to reduce dependence on petroleum resources, my country has carried out the promotion of the application of methanol as a clean alternative fuel. Methanol has the characteristics of high oxygen content, wide source and low price. Single-cylinder diesel engines are the main power of small agricultural machinery in my country. Mixing methanol in single-cylinder diesel engines is of great significance for effectively reducing emissions, reducing dependence on oil, and protecting the environment.

At present, the main methods of blending methanol in diesel engines are: direct blending of methanol/diesel fuel, and methanol injection in the intake port. Using the direct blending method of diesel and methanol fuel, it is not necessary to modify the single-cylinder diesel engine, but the mixed fuel formed by methanol/diesel is easy to stratify, the mixing amount of methanol is low, and the cold start is poor. problems such as adjustment of working conditions. The port methanol injection method is suitable for large multi-cylinder diesel engines. The structure of the port methanol injection system is complex and the accuracy is high, so it is difficult to apply to single-cylinder diesel engines.

SUMMARY OF THE INVENTION

In order to solve the deficiencies in the prior art, according to the characteristics of the single-cylinder diesel engine, the present invention proposes a control system and method for mixing gaseous methanol fuel with the single-cylinder diesel engine. , determine the optimal mixing ratio, and achieve the best match between the methanol mixing ratio and the operating conditions of a single-cylinder diesel engine.

The technical scheme adopted in the present invention is as follows:

A control system for mixing gaseous methanol fuel with a single-cylinder diesel engine, comprising a methanol pipeline arranged on an intake pipe and an intake pipe differential pressure sensor, the methanol pipeline is provided with an electronically controlled double-opening semicircular valve, the electronically controlled double-opening semicircular valve and The intake pipe differential pressure sensors are all signal-connected to the methanol control unit, and the intake pipe differential pressure sensors are used to measure the pressure in the intake passage of the diesel engine. The methanol control unit is also connected to the accelerator position sensor, the exhaust temperature sensor and the rotational speed sensor, respectively. The methanol control unit controls the opening and closing of the electronically controlled double-opening semi-circular valve according to the collected throttle opening, exhaust temperature, rotational speed and diesel engine inlet pressure, thereby adjusting the mixing ratio of methanol.

Further, the electronically controlled double-opening semi-circular valve includes two oppositely arranged semi-circular baffles, a gear is installed at one end of each semi-circular baffle on the same side, the gear and the corresponding semi-circular baffle are welded into one, and can be wound around the axis of the gear. The heart rotates, and the two gears can mesh with each other; one of the gears meshes with the gear on the output shaft of the stepper motor. Through the work of the stepper motor, the two semicircular baffles can be controlled to rotate in the opposite direction or in the opposite direction, and finally the electronic control can be realized. Adjustment of the opening of the double-opening semi-circle valve;

Further, the intake pipe differential pressure sensor includes a rubber diaphragm arranged along the side wall surface of the intake pipe 1, the upper surface of the rubber diaphragm is connected to the Hall element through a moving block, and the moving block has magnetism; the Hall element is connected to the methanol control unit through a data line ; When the diesel engine is running, due to the pressure difference between the upper and lower surfaces of the rubber diaphragm, the rubber diaphragm is deformed, which drives the moving block to move up and down, and the Hall element converts the displacement signal of the moving block into a potential difference and inputs it to the methanol control unit. The potential difference calculates the pressure P _j in the diesel intake port;

其中，甲醇的流量

C为流量系数，θ为电控双开半圆阀的开度角，r为管道的半径，P_j是柴油机进气道中的压力，T_w是甲醇管道中的温度，P_x为甲醇管道中气态甲醇的压力，M_d为柴油的消耗。Further, the relationship between the mixing ratio α of methanol and the opening degree of the electronically controlled double-opening semicircular valve is expressed as:

Among them, the flow of methanol

C is the flow coefficient, θ is the opening angle of the electronically controlled double-opening semicircular valve, _r is the radius of the pipe, P _j is the pressure in the diesel engine intake port, Tw is the temperature in the methanol pipe, P _x is the gaseous methanol in the methanol pipe pressure, M _d is the consumption of diesel.

A control method for blending gaseous methanol fuel with a single-cylinder diesel engine, comprising the following steps:

Step 1. The methanol control unit judges whether the diesel engine is in the working area according to the throttle opening, speed and exhaust temperature; if it is in the working area, it starts to mix methanol; if it is not in the working area, it does not mix methanol, and only Cylinder diesel engine operates only in pure diesel mode;

Step 2, based on the rotation speed-exhaust temperature-methanol mixing and burning ratio strategy map, obtain the maximum mixing and burning ratio α _max1 according to the rotation speed and exhaust temperature at this time; based on the rotation speed-power-methanol mixing and burning ratio strategy map, according to the current The maximum doping ratio α _max2 is obtained from the rotational speed and power, and the optimum doping ratio α _w is obtained by correcting the obtained two maximum doping ratios. The correction method is α _w =min(α _max1 , α _max2 ), where α _max1 is the maximum mixing ratio obtained according to the strategy map of the methanol mixing ratio of the speed-exhaust temperature, and α _max2 is the mixing ratio according to the speed-power The maximum doping ratio from the strategy map.

Step 3. The opening degree of the electronically controlled double-opening semi-circular valve is adjusted by the methanol control unit to realize the optimal mixing and burning ratio α _w .

Further, the drawing method of the rotational speed-exhaust gas temperature-methanol admixture ratio strategy map is:

S1.1, through the single-cylinder diesel engine bench experiment, collect the operating points in the normal operating range of the single-cylinder diesel engine, record the speed and temperature corresponding to all the operating points of the single-cylinder diesel engine under normal operation; select the operating points by box , forming a speed-exhaust temperature diagram of a single-cylinder diesel engine;

S1.2, the speed-exhaust temperature map of the single-cylinder diesel engine obtained in S1 is divided into regions based on:

When t<t _wmin or n<n _wmin , that is, when the single-cylinder diesel engine is in idle speed and low load conditions, at this time, no methanol is mixed with α _max =0%;

When t _wmin <t<t ₁ or n _wmin <n<n ₁ , α _max =10%;

When t ₁ <t<t ₂ or n ₁ <n<n ₂ , at this time α _max =20%;

When t ₂ <t<t ₃ or n ₂ <n<n ₃ , α _max =30%;

When t ₃ <t<t ₄ or n ₃ <n<n ₄ , α _max =20%;

When t ₄ <t<t _wmax or n ₄ <n<n _wmax , at this time α _max =10%;

When t _wmax <t<t _max or n _wmax <n<n _max , α _max =0% of methanol is not mixed at this time;

Among them, t exhaust temperature, n is the speed, n _wmin is the minimum speed of the single-cylinder diesel engine mixed with methanol; t _wmin is the minimum exhaust temperature of mixed methanol; n _wmax is the maximum speed of mixed methanol, t _wmax is mixed with methanol The maximum exhaust temperature of burning methanol, n _max is the maximum speed of the single-cylinder diesel engine, t _max is the maximum exhaust temperature of the single-cylinder diesel engine, n ₁ , n ₂ , n ₃ , and n ₄ are the rotation speeds respectively, and n3 is the maximum torque point speed, n ₂ =(n ₃ +n _wmin )/2, n ₁ =(n ₂ +n _wmin )/2, n ₄ =(n ₃ +n _wmax )/2; t ₁ , t ₂ , t ₃ , t ₄ are the temperatures, respectively, and t ₃ is the maximum torque point temperature, t ₁ =(t ₂ +t _wmin )/2, t ₂ =(t ₃ +t _wmin )/2, t ₄ =(t ₃ +t _wmax )/2. .

Further, the drawing method of the rotational speed-power-methanol admixture ratio strategy map is:

S2.1, draw a single-cylinder diesel engine power-speed diagram according to the power and speed of the single-cylinder diesel engine;

S2.2, for the single-cylinder diesel engine power-speed map obtained in S2.1, perform regional division on the basis of:

When n<n _wmin or p<p _wmin , at this time α _max =0%;

When n _wmin <n<n ₁ or p _wmin <p<p ₁ , α _max =10%;

When n ₁ <n<n ₂ or p ₁ <p<p ₁ , α _max =20%;

When n ₂ <n<n ₃ or p ₂ <p<p ₃ , α _max =30%;

When n ₃ <n<n ₄ or p ₃ <p<p ₄ , α _max =20%;

When n ₄ <n<n _wmax or p ₄ <p<p _wmax , α _max =10%;

When n _wmax <n<n _max or p _wmax <p<p _max , at this time α _max =0%;

Among them, p _wmin is the minimum power of the mixed-burning methanol, p _wmax is the maximum power of the mixed-burning methanol, and p _max is the maximum power of a single-cylinder diesel engine.

Beneficial effects of the present invention:

The invention determines the maximum mixing ratio and the optimum mixing ratio of the single-cylinder diesel engine according to parameters such as accelerator position, rotational speed and exhaust gas temperature. According to the operating conditions of the diesel engine, the opening of the electronically controlled double-opening semi-circular valve can be adjusted through the MSCU, and the supply of methanol can be adjusted, thereby changing the mixing ratio of methanol, and realizing the best methanol mixing ratio and single-cylinder diesel engine operating conditions. best match.

The mixing ratio of methanol in the present invention is selected by dividing the rotation speed-exhaust temperature diagram of the single-cylinder diesel engine and the single-cylinder diesel engine power-rotation speed diagram into multiple parts, and then selecting them according to the relationship between the rotation speed, temperature and power respectively. The optimum blending ratio α _w can take into account the safety of single-cylinder diesel engine blending methanol and the power performance of single-cylinder diesel engine blending methanol.

Description of drawings

Fig. 1 is the overall view of the control device;

Figure 2 is a structural diagram of an intake pipe differential pressure sensor;

Figure 3 is a structural diagram of an electronically controlled double-opening semicircular valve;

Figure 4 is the parameter definition diagram of the electronically controlled double-opening semicircular valve;

Fig. 5 is a strategy diagram of the methanol mixing ratio of rotational speed-exhaust temperature;

Fig. 6 is the strategy diagram of speed-power methanol mixing and burning ratio;

In the figure, 1. Intake port, 2. Electronically controlled double-opening semicircular valve, 3. Methanol pipeline, 4. Throttle position sensor, 5. Exhaust temperature sensor, 6. Speed sensor, 7. Methanol control unit, 8. Intake pipe Differential pressure sensor, 9, Hall element, 10, motion block, 11, rubber diaphragm, 12, semicircle baffle, 13, stepper motor, 14, gear.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

As shown in FIG. 1, a control system for blending gaseous methanol fuel with a single-cylinder diesel engine includes a methanol pipeline 3 and an intake pipe differential pressure sensor 8 arranged on the intake pipe 1, and the methanol pipeline 3 is equipped with an electronically controlled double-opening semicircle. Valve 2, the electronically controlled double-opening semi-circular valve 2 and the intake pipe differential pressure sensor 8 are all signal-connected to the methanol control unit 7 (Methanol Supply Control Unit), and the intake pipe differential pressure sensor 8 is used to measure the pressure in the intake passage of the diesel engine , the methanol control unit 7 is also connected to the accelerator position sensor 4, the exhaust temperature sensor 5 and the rotational speed sensor 6, wherein the accelerator position sensor 4 is used to measure the opening of the accelerator, and the exhaust temperature sensor 5 is used to measure the exhaust gas of the diesel engine. gas temperature, and the rotational speed sensor 6 is used to collect the rotational speed of the single-cylinder diesel engine; the methanol control unit 7 controls the opening and closing of the electronically controlled double-opening semicircular valve 2 according to the collected throttle opening, exhaust temperature, rotational speed and diesel engine intake port pressure Then adjust the mixing ratio of methanol.

In this embodiment, the intake pipe differential pressure sensor 8 is composed of a Hall element 9 , a moving block 10 , and a rubber diaphragm 11 . As shown in FIG. 2 , a rubber diaphragm 11 is arranged along the side wall of the intake pipe 1 , the lower part of the rubber diaphragm 11 is connected to the air intake 1 , the upper part of the rubber diaphragm 11 is atmospheric pressure, and the upper surface of the rubber diaphragm 11 passes through the moving block 10 . The Hall element 9 is connected, and the motion block 10 has magnetism; the Hall element 9 is connected to the methanol control unit 7 through the data cable; when the diesel engine is running, due to the pressure difference between the upper and lower surfaces of the rubber diaphragm 11, the rubber diaphragm 11 is deformed and drives the movement The block 10 moves up and down, and the Hall element 9 converts the displacement signal of the moving block 10 into a potential difference and inputs it to the methanol control unit 7. The methanol control unit 7 calculates the pressure P _j in the diesel engine intake port according to the potential difference.

In order to effectively control the mixing ratio of methanol, the present invention optimizes the design of the electronically controlled double-opening semicircular valve 2 on the methanol pipeline 3, as shown in FIG. 3, the electronically controlled double-opening semicircular valve 2 includes two semicircular baffles 12, The baffles 12 are arranged opposite to each other, and a gear 14 is installed at one end of each semicircular baffle 12 on the same side. The gear 14 is welded with the corresponding semicircular baffle 12 and can rotate around the axis of the gear 14. The two gears 14 can One of the gears 14 meshes with the gear on the output shaft of the stepper motor 13. Through the operation of the stepper motor 13, the two semicircular baffles 12 can be controlled to rotate in the opposite direction or in the opposite direction, and finally the electronically controlled double-opening semicircular valve can be realized. 2 opening adjustment.

r为管道的半径，θ为半圆挡片边与竖直线的夹角。As shown in FIG. 4 , the included angle between the two semi-circular baffles 12 in the electronically controlled double-opening semi-circular valve 2 is the opening angle θ, and the range of θ is 0 to 45°, that is, the maximum opening is 45°. area

r is the radius of the pipe, and θ is the angle between the edge of the semicircular baffle and the vertical line.

The principle of adjusting the mixing ratio of methanol through the opening of the electronically controlled double-opening semicircular valve 2 is as follows:

The mass flow Q _m (Kg/s) of methanol is expressed as:

P_x为甲醇管道3中气态甲醇的压力，M为甲醇分子质量，即32；理想气体常数R＝8.314；将甲醇气体的密度代入式(1)得到：ρ _m is the density of methanol gas,

P _x is the pressure of gaseous methanol in methanol pipeline 3, M is the molecular mass of methanol, namely 32; ideal gas constant R=8.314; Substitute the density of methanol gas into formula (1) to obtain:

Among them, C is the flow coefficient, A is the open area of the electronically controlled double-opening semicircular valve 2, P _j is the pressure in the diesel engine intake port, _Tw is the temperature in the methanol pipeline 3, which is generally a fixed value;

其中M_d为柴油的消耗，Q_m为甲醇的流量。The methanol control unit 7 (MSCU) calculates the consumption of diesel oil M _d (Kg/s) according to the fuel injection amount and the rotational speed of the diesel engine, and adjusts the opening of the electronically controlled double-opening semicircular valve 2 to adjust the supply of methanol, so that methanol is mixed with burning than to achieve the required α,

where M _d is the consumption of diesel and Q _m is the flow of methanol.

A control method for blending gaseous methanol fuel with a single-cylinder diesel engine, comprising the following steps:

Step 1. The methanol control unit 7 judges whether the diesel engine is in the working area (that is, whether the diesel engine is in the medium load condition) according to the throttle opening, the rotational speed and the exhaust gas temperature; if it is in the working area (the medium load condition), then Start mixing methanol; if it is not in the working area (that is, the diesel engine is in idle speed, low load condition and high load condition), methanol is not mixed, and the single-cylinder diesel engine only runs in pure diesel mode;

Step 2, based on the rotation speed-exhaust temperature-methanol mixing and burning ratio strategy map, obtain the maximum mixing and burning ratio α _max1 according to the rotation speed and exhaust temperature at this time; based on the rotation speed-power-methanol mixing and burning ratio strategy map, according to the current The maximum doping ratio α _max2 is obtained from the rotational speed and power, and the optimum doping ratio α _w is obtained by correcting the obtained two maximum doping ratios. The correction method is α _w =min(α _max1 , α _max2 ), where α _max1 is the maximum mixing ratio obtained according to the strategy map of the methanol mixing ratio of the speed-exhaust temperature, and α _max2 is the mixing ratio according to the speed-power The maximum doping ratio from the strategy map.

The above strategy map of rotational speed-exhaust temperature-methanol admixture ratio divides the speed-exhaust temperature map of a single-cylinder diesel engine into multiple state intervals; the method for drawing the rotational speed-exhaust temperature-methanol admixture ratio strategy map is as follows:

S1.1, first, draw the speed-exhaust temperature diagram of the single-cylinder diesel engine. Specifically, through the single-cylinder diesel engine bench experiment, collect the operating points in the normal operating range of the single-cylinder diesel engine, and compare all the operating points under normal operation. Record the corresponding speed and temperature; select the recorded points to form a speed-exhaust temperature map, that is, the diamond-shaped area in Figure 5 is obtained.

S1.2, the speed-exhaust temperature map of the single-cylinder diesel engine obtained in S1 is divided into regions based on:

When t<t _wmin or n<n _wmin , that is, when the single-cylinder diesel engine is in idle speed and low-load conditions, α _max =0% is not mixed with methanol; that is, the area a in FIG. 5 .

When t _wmin <t<t ₁ or n _wmin <n<n ₁ , at this time α _max =10%; that is, the b region in FIG. 5 .

When t ₁ <t<t ₂ or n ₁ <n<n ₂ , at this time α _max =20%; that is, region c in FIG. 5 .

When t ₂ <t<t ₃ or n ₂ <n<n ₃ , at this time α _max =30%; that is, the area d in FIG. 5 .

When t ₃ <t<t ₄ or n ₃ <n<n ₄ , at this time α _max =20%; that is, the c′ region in FIG. 5 .

When t ₄ <t<t _wmax or n ₄ <n<n _wmax , at this time α _max =10%; that is, the b′ region in FIG. 5 .

When t _wmax <t<t _max or n _wmax <n<n _max , at this time, α _max =0% of undoped methanol; that is, the a' region in FIG. 5 .

Among them, t exhaust temperature, n is the speed, n _wmin is the minimum speed of the single-cylinder diesel engine mixed with methanol; t _wmin is the minimum exhaust temperature of mixed methanol; n _wmax is the maximum speed of mixed methanol, t _wmax is mixed with methanol The maximum exhaust temperature of burning methanol, n _max is the maximum speed of the single-cylinder diesel engine, t _max is the maximum exhaust temperature of the single-cylinder diesel engine, n ₁ , n ₂ , n ₃ , and n ₄ are the rotation speeds respectively, and n3 is the maximum torque point speed, n ₂ =(n ₃ +n _wmin )/2, n ₁ =(n ₂ +n _wmin )/2, n ₄ =(n ₃ +n _wmax )/2; t ₁ , t ₂ , t ₃ , t ₄ are the temperatures, respectively, and t ₃ is the maximum torque point temperature, t ₁ =(t ₂ +t _wmin )/2, t ₂ =(t ₃ +t _wmin )/2, t ₄ =(t ₃ +t _wmax )/2; the maximum mixing ratio is determined according to the speed-exhaust temperature diagram of the single-cylinder diesel engine, which can ensure the safety of mixing methanol with the single-cylinder diesel engine.

The above strategy map of speed-power-methanol blending and burning ratio divides the single-cylinder diesel engine power-speed map into multiple state intervals. The method of drawing the strategy map of rotating speed-power-methanol blending and burning ratio is as follows:

S2.1, first, draw a single-cylinder diesel engine power-speed diagram according to the power and speed of the single-cylinder diesel engine;

S2.2, for the single-cylinder diesel engine power-speed map obtained in S2.1, perform regional division on the basis of:

When n<n _wmin or p<p _wmin , at this time α _max =0%; that is, the e region in FIG. 6 .

When n _wmin <n<n ₁ or p _wmin <p<p ₁ , at this time α _max =10%; that is, the f region in FIG. 6 .

When n ₁ <n<n ₂ or p ₁ <p<p ₁ , at this time α _max =20%; that is, the g area in FIG. 6 .

When n ₂ <n<n ₃ or p ₂ <p<p ₃ , at this time α _max =30%; that is, the h region in FIG. 6 .

When n ₃ <n<n ₄ or p ₃ <p<p ₄ , at this time α _max =20%; that is, the g' area in FIG. 6 .

When n ₄ <n<n _wmax or p ₄ <p<p _wmax , at this time α _max =10%; that is, the f' area in FIG. 6 .

When n _wmax <n<n _max or p _wmax <p<p _max , at this time α _max =0%; that is, the area e in FIG. 6 .

Among them, pwmin is the minimum power of mixed-burning methanol, pwmax is the highest power of mixed-burning methanol, and pmax is the highest power of single-cylinder diesel engine;

The maximum mixing ratio is determined according to the power-speed diagram of the single-cylinder diesel engine, which can ensure the power performance of the single-cylinder diesel engine mixing methanol.

Step 3. The opening degree of the electronically controlled double-opening semi-circular valve 2 is adjusted by the methanol control unit 7 to realize the optimal mixing and burning ratio α _w .

Further explanation is made below in conjunction with the working process of the present invention:

1) After the power is turned on, the MSCU detects the ambient temperature of the single-cylinder diesel engine, determines the deformation rate of the rubber diaphragm, and ensures the accuracy of the differential pressure sensor. The correction coefficient A of the pressure sensor is set, and the final pressure Pz=AP _j is obtained by correction. When the temperature is -30～-10℃, the correction factor is A1, and the range is 1～1.2; when the temperature is -10～20℃, the correction factor is A2, and the value is 1; when the temperature is 20～40℃, the correction factor is A3, A3 The range is 0.9～1; when 40～60℃, the correction coefficient is A4, and the range is 0.8～0.9.

2) After the diesel engine is started, the MSCU detects the throttle opening, detects the rotational speed and the exhaust temperature. If it is in the working area, it starts to mix methanol; if the conditions are not met, it does not mix methanol, and the single-cylinder diesel engine runs in pure diesel mode.

3) _MSCU determines the optimal methanol mixing ratio αw under this working condition according to the rotation speed and exhaust temperature, and on this basis, according to the strategy map of the methanol mixing and burning ratio of the rotation speed-exhaust temperature and the strategy map of the speed-power mixing and burning ratio and the maximum mixing ratio α _max , MSCU calculates the methanol supply according to the stored fuel injection quantity, and adjusts the opening of the electronically controlled double-opening semicircular valve, so that the methanol mixing ratio reaches the optimal mixing ratio α _w .

4) When the single-cylinder diesel engine is blending with methanol, the MSCU can monitor the throttle position and speed changes of the diesel engine in real time, compare it with the data of the previous cycle, and correct the methanol blending ratio. If the throttle opening does not change , the speed increases, the opening of the electronically controlled double-opening semicircular valve 2 is reduced, the speed increase is less than 50r/min, and the methanol supply is reduced by 10%; the increase range is 50-100r/min, and the methanol supply is reduced by 20%. , the increase range is between 100-150r/min, reduce the methanol supply by 30%; the increase range is between 150-200r/min, reduce the methanol supply by 40%; when the increase range exceeds 200r/min, close the electronic control double-open Half-circle valve 2. If the speed decreases, it means that the real-time load of the single-cylinder diesel engine increases, and the opening of the electronically controlled double-opening semicircular valve 2 needs to be increased. When the speed reduction is less than 50r/min, increase the methanol supply by 10%; the speed decreases by 50r/min. , Increase the methanol supply by 10% to enhance its power, but the increased methanol amount does not exceed the limit value, that is, the modified blending ratio must not exceed the maximum blending ratio α _max .

The above embodiments are only used to illustrate the design ideas and features of the present invention, and the purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly, and the protection scope of the present invention is not limited to the above embodiments. Therefore, all equivalent changes or modifications made according to the principles and design ideas disclosed in the present invention fall within the protection scope of the present invention.

Claims (7)

1. a control method of single-cylinder diesel engine blending gaseous methanol fuel, is characterized in that, comprises the steps: Step 1. The methanol control unit (7) judges whether the diesel engine is in the working area according to the throttle opening, rotational speed and exhaust temperature; if it is in the working area, it starts to mix methanol; if it is not in the working area, it does not mix. Methanol, single-cylinder diesel engine only operates in pure diesel mode; Step 2, based on the rotation speed-exhaust temperature-methanol mixing and burning ratio strategy map, obtain the maximum mixing and burning ratio α _max1 according to the rotation speed and exhaust temperature at this time; based on the rotation speed-power-methanol mixing and burning ratio strategy map, according to the current The maximum mixing ratio α _max2 is obtained from the rotational speed and power, and the obtained two maximum mixing ratios are corrected to obtain the optimal mixing ratio α _w ; the correction method is α _w =min(α _max1 , α _max2 ), where, α _max1 is the maximum mixing ratio obtained according to the strategy map of speed-exhaust temperature methanol mixing and burning ratio, and α _max2 is the maximum mixing ratio obtained according to the strategy map of speed-power mixing and burning ratio; In step 3, the opening degree of the electronically controlled double-opening semicircular valve (2) is adjusted by the methanol control unit (7), so as to realize the optimum mixing and burning ratio α _w . 2. the control method of a kind of single-cylinder diesel engine blending gaseous methanol fuel according to claim 1, is characterized in that, the drawing method of described rotating speed-exhaust temperature-methanol blending ratio strategy diagram is: S1.1, through the single-cylinder diesel engine bench experiment, collect the operating points in the normal operating range of the single-cylinder diesel engine, record the speed and temperature corresponding to all operating operating points of the single-cylinder diesel engine under normal operation; select the operating points by box , forming a speed-exhaust temperature diagram of a single-cylinder diesel engine; S1.2, the speed-exhaust temperature map of the single-cylinder diesel engine obtained in S1 is divided into regions based on: When t<t _wmin or n<n _wmin , that is, when the single-cylinder diesel engine is in idle speed and low load conditions, at this time, no methanol is mixed with α _max =0%; When t _wmin <t<t ₁ or n _wmin <n<n ₁ , α _max =10%; When t ₁ <t<t ₂ or n ₁ <n<n ₂ , at this time α _max =20%; When t ₂ <t<t ₃ or n ₂ <n<n ₃ , α _max =30%; When t ₃ <t<t ₄ or n ₃ <n<n ₄ , α _max =20%; When t ₄ <t<t _wmax or n ₄ <n<n _wmax , at this time α _max =10%; When t _wmax <t<t _max or n _wmax <n<n _max , α _max =0% of methanol is not mixed at this time; Among them, t exhaust temperature, n is the speed, n _wmin is the minimum speed of the single-cylinder diesel engine mixed with methanol; t _wmin is the minimum exhaust temperature of mixed methanol; n _wmax is the maximum speed of mixed methanol, t _wmax is mixed with methanol The maximum exhaust temperature of burning methanol, n _max is the maximum speed of the single-cylinder diesel engine, t _max is the maximum exhaust temperature of the single-cylinder diesel engine, n ₁ , n ₂ , n ₃ , and n ₄ are the rotation speeds respectively, and n ₃ is the maximum torque point speed, n ₂ =(n ₃ +n _wmin )/2, n ₁ =(n ₂ +n _wmin )/2, n ₄ =(n ₃ +n _wmax )/2; t ₁ , t ₂ , t ₃ , and t ₄ are temperatures, respectively, and t ₃ is the maximum torque point temperature, t ₁ =(t ₂ +t _wmin )/2, t ₂ =(t ₃ +t _wmin )/2, t ₄ =( t ₃ +t _wmax )/2. 3. the control method of a kind of single-cylinder diesel engine blending gaseous methanol fuel according to claim 1, is characterized in that, the drawing method of described rotational speed-power-methanol blending ratio strategy diagram is: S2.1, draw a single-cylinder diesel engine power-speed diagram according to the power and speed of the single-cylinder diesel engine; S2.2, for the single-cylinder diesel engine power-speed map obtained in S2.1, perform regional division on the basis of: When n<n _wmin or p<p _wmin , at this time α _max =0%; When n _wmin <n<n ₁ or p _wmin <p<p ₁ , α _max =10%; When n ₁ <n<n ₂ or p ₁ <p<p ₁ , α _max =20%; When n ₂ <n<n ₃ or p ₂ <p<p ₃ , α _max =30%; When n ₃ <n<n ₄ or p ₃ <p<p ₄ , α _max =20%; When n ₄ <n<n _wmax or p ₄ <p<p _wmax , α _max =10%; When n _wmax <n<n _max or p _wmax <p<p _max , at this time α _max =0%; Among them, p _wmin is the minimum power of the mixed-burning methanol, p _wmax is the maximum power of the mixed-burning methanol, and p _max is the maximum power of a single-cylinder diesel engine. 4. A system for realizing the control method for blending gaseous methanol fuel of a single-cylinder diesel engine according to any one of claims 1-3, characterized in that it comprises a methanol pipeline arranged on the intake pipe (1) (3) and an intake pipe differential pressure sensor (8), the methanol pipeline (3) is equipped with an electronically controlled double-opening semicircular valve (2), the electronically controlled double-opening semicircular valve (2) and the intake pipe differential pressure sensor (8) Both are connected with the signal of the methanol control unit (7), the intake pipe differential pressure sensor (8) is used to measure the pressure in the intake port of the diesel engine, and the methanol control unit (7) is also connected to the accelerator position sensor (4), the exhaust gas An air temperature sensor (5) and a rotational speed sensor (6), the methanol control unit (7) controls the electronically controlled double-opening semicircular valve (2) according to the collected accelerator opening, exhaust temperature, rotational speed and diesel engine intake port pressure. Open and close to adjust the mixing ratio α of methanol. 5. The control system of a single-cylinder diesel engine blending gaseous methanol fuel according to claim 4, wherein the electronically controlled double-opening semicircular valve (2) comprises two oppositely arranged semicircular baffles (12), A gear (14) is fixedly mounted on the same side end of each semicircular baffle (12), and the two gears (14) mesh with each other; one of the gears (14) meshes with the gear on the output shaft of the stepping motor (13), The stepper motor (13) drives the two semicircular blocking pieces (12) to rotate in the opposite direction or in the opposite direction, so as to finally realize the adjustment of the opening degree of the electronically controlled double-opening semicircular valve (2). 6. The control system of a single-cylinder diesel engine blending gaseous methanol fuel according to claim 4, wherein the intake pipe differential pressure sensor (8) comprises a rubber diaphragm provided along the sidewall surface of the intake pipe (1) (11), the upper surface of the rubber diaphragm (11) is connected to the Hall element (9) through the moving block (10); the Hall element (9) is connected to the methanol control unit (7) through the data line; when the diesel engine is running, due to The pressure difference between the upper and lower surfaces of the rubber diaphragm (11) causes the rubber diaphragm (11) to deform, driving the moving block (10) to move up and down, and the Hall element (9) converts the displacement signal of the moving block (10) into a potential difference and inputs it A methanol control unit (7), the methanol control unit (7) calculates the pressure P _j in the intake port of the diesel engine according to the potential difference. 7. The control system of a single-cylinder diesel engine blending gaseous methanol fuel according to claim 4, characterized in that, the relationship between the blending ratio α of the methanol and the opening degree of the electronically controlled double-opening semicircular valve (2) is expressed as for:

Among them, the flow of methanol

C is the flow coefficient, θ is the opening angle of the electronically controlled double-opening semicircular valve 2, _r is the radius of the pipe, P _j is the pressure in the diesel engine intake port, Tw is the temperature in the methanol pipeline 3, and P _x is the methanol pipeline 3 pressure of gaseous methanol in medium, M _d is the consumption of diesel.

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