CN104454190A - Intra-cylinder direct injection double gas fuel ignition type combustion and control device - Google Patents

Abstract

The present invention relates to an ignition type combustion and control device with direct injection of dual gas fuels in the cylinder. The dual fuel storage tanks in this experimental model are respectively connected to their respective nozzles through pressure reducing valves. Both fuels are directly injected into the cylinder of the engine. Therefore, the combustion device of this invention has all the advantages of the direct injection ignition type engine in the cylinder. In addition, the combustion device has also canceled the throttle valve of the traditional ignition type engine, reduced the pumping loss in the intake process, and is equipped with an exhaust gas turbocharger. Compressor, which can improve the charging efficiency, and can increase the power per liter compared with non-direct injection gas fuel engines. A fuel injector in the cylinder is near the spark plug, and cooperates with the special shape of the piston. Ensure reliable ignition, while another fuel forms a leaner mixture with air to achieve overall lean combustion of the engine, reduce emissions, reduce oil consumption, ease the pressure of oil shortages, and reduce environmental pollution.

Description

An in-cylinder direct injection dual gas fuel ignition type combustion and control device

technical field

The invention relates to the technical field of internal combustion engines for vehicles, in particular to gas fuel internal combustion engine control and in-cylinder direct injection engines.

Background technique

As the number of automobiles increases year by year, the amount of oil consumed by automobiles also increases year by year. In addition, the proven oil reserves in the world continue to decrease, and the harmful gases emitted by automobiles after burning petroleum fuels cause more serious and irreversible pollution to the environment. Therefore, the development of automobiles has higher and higher requirements for high efficiency and energy saving. With the aggravation of air pollution and increasingly stringent emission regulations, it is imperative to find high-quality engine alternative fuels for automobiles and to explore new combustion modes for engines. High-quality alternative fuels for engines can reduce the pressure brought by automobiles on the shortage of oil resources and reduce the energy crisis. The engine of the new combustion mode can theoretically not only reduce the fuel consumption of the engine, but also reduce the emission of harmful substances, and at the same time achieve the purpose of reducing energy consumption and pollution. Automobile development must take a sustainable development path that coexists harmoniously with the energy environment.

In recent years, gaseous fuel engines have received increasing attention, but traditional gaseous fuel engines have certain shortcomings. Gaseous fuel and air enter the engine cylinder together, and gaseous fuel occupies a part of the intake air volume, which reduces the intake air volume and improves the charging efficiency. Decrease; the net energy density of gaseous fuel is lower than that of petroleum fuel, so that the power of the engine is reduced, and the power cannot meet the driving requirements during lean combustion. Based on the above-mentioned technical background and the problems existing in the existing gas fuel engine, the dual fuel engine involved in the present invention overcomes the shortcomings of the existing gas fuel engine, and can realize multiple combustion modes, and can switch between different combustion modes , to achieve high-efficiency and low-emission combustion of the engine.

In-cylinder direct injection technology means that the fuel injector is placed between the intake and exhaust valves, and high-pressure fuel is directly injected into the combustion chamber for smooth and efficient combustion. Through uniform combustion and stratified combustion, the power output is guaranteed It is a technology to reduce the fuel consumption rate under certain circumstances, especially a technology that reduces the fuel consumption under small loads, and at the same time greatly reduces the tendency of knocking, but greatly improves the power performance. At present, there are two main combustion modes of the direct injection engine, one is the stratified combustion mode, and the other is the homogeneous combustion mode. In China, the combustion method of the direct injection engine is the homogeneous combustion mode. This is because the stratified combustion mode has high requirements on the quality of the oil. It is difficult to improve the quality of oil products, so domestic direct injection engines have always adopted the homogeneous combustion mode. However, the homogeneous combustion mode is difficult to achieve lean combustion of the engine, which limits the improvement of engine economy.

Contents of the invention

The invention is an in-cylinder direct-injection dual-gas fuel ignition type combustion device, aiming to solve the shortcomings of traditional gas-fuel engines and the problems that domestic in-cylinder direct-injection engines cannot achieve stratified combustion and combustion products are difficult to control. The invention can also make the engine burn at a larger air-fuel ratio and work at a higher compression ratio. Through the control system, the engine can work in different combustion modes under different working conditions, so that the engine can correspond to the optimal combustion mode under various working conditions, and work stably and efficiently in the optimal mode.

The above object of the present invention is achieved through the following technical solutions, which are described in detail in conjunction with the accompanying drawings.

Referring to shown in Fig. 1, the present invention is a kind of in-cylinder direct injection dual gas fuel stratified combustion device, consists of engine 1, supercharger 4, dual fuel storage tanks 2 and 3, three-way catalytic converter 6, electronic control unit 5 and so on. The engine is composed of intake system, exhaust system, dual gas fuel supply system, cooling system, lubrication system, ignition system and so on. The dual fuel supply system consists of fuel storage tanks 2 and 3, gas fuel pipelines, gas fuel decompression devices 7 and 10, high-pressure gas rails 17 and 18, gas fuel nozzles 9 and 12, gas fuel leakage alarm devices 20 and 21, etc. , The gaseous fuel storage tanks 2, 3 are connected to respective nozzles 9, 12, and each nozzle injects fuel directly into the engine cylinder. The engine supercharger 4 is connected with the exhaust pipe 15 of the engine, and supercharges the intake air of the engine. The EGR system is connected with the exhaust pipe and intake pipe of the engine, so that the exhaust gas enters the supercharger together with the air. The electronic control device 5 receives various operating parameter signals of the engine, specifically including: accelerator pedal position signal, engine speed signal, crankshaft position signal, camshaft position signal, lubricating oil pressure signal, lubricating oil temperature signal, cooling water temperature signal, Gas temperature and pressure signals, oxygen concentration signals in exhaust gas, detonation signals, dual fuel temperature and pressure signals, the output end controls the nozzles, spark plugs, superchargers, EGR valves and other devices of the dual fuel engine. The gaseous fuel in the above-mentioned dual fuel tank is not two specific fuels, the flame propagation speed of the gaseous fuel A (auxiliary fuel) is higher than that of fuel B (main fuel), and the ignition energy is lower than that of fuel B, while fuel A The octane rating is higher. The main requirements for Fuel B are that the octane number of Fuel B should be high, and the net energy density of Fuel B should be relatively high.

The present invention relates to an in-cylinder direct injection dual gas fuel combustion and control device. The engine in the device is an ignition engine. The purpose of the invention is to realize the stratified combustion of the engine and the stable combustion of the engine at a larger air-fuel ratio. After the lean combustion of the engine, the knocking tendency of the engine is reduced, and the compression ratio of the engine can be appropriately increased so that the economy of the engine can be further improved. improve. We design the compression ratio of the engine to be 12, which is higher than that of the traditional gasoline engine, which can improve the thermal efficiency of the engine; another point worth mentioning is that the invention cancels the throttle valve of the traditional ignition engine and reduces The pumping loss of the engine improves the charging efficiency. Domestic in-cylinder direct-injection lean-burn gasoline engines only have the throttle valve fully open under heavy load, but the throttle valve is not fully open under medium and small loads. Therefore, the engine has throttling loss under medium and small loads. There is no throttling loss, and the intake efficiency is greatly improved. The dual fuel of the engine adopts direct injection in the cylinder, which has all the advantages of the direct injection engine. The dual direct injection system of the engine has also been specially designed, especially the position of the nozzle of fuel A and the spark plug, as well as the position of the nozzle of fuel A and the shape of the piston. An easy-to-ignite mixture can be formed near the spark plug, that is, a partially rich mixture of fuel A and air is formed near the spark plug, making it easy to ignite, and then ignites the mixture formed by fuel B and air to make the engine work smoothly. Special design requires special control. In the present invention, the direct injection of two fuels in the cylinder also needs to cooperate with the ignition of the spark, so there are two injection timings and one ignition timing. The control of these three timings is crucial to the present invention. especially important. In order to control these three boundary conditions, the present invention conducts a large number of simulations for these three boundary conditions, the purpose is to find out the best cooperation at three moments under different working conditions, and implement optimal control under different working conditions . And do the same simulation experiment in each combustion mode to find out the optimal control parameters to realize the control of the engine. The dual-fuel supply of the engine in the present invention and the direct injection in the cylinder of the dual-fuel can make the engine realize the optimal combustion mode corresponding to this working condition under different operating conditions:

1. Start-up and warm-up conditions (Type A combustion mode): Traditional engines need to give the engine a richer mixture in the start-up condition to make the engine start reliably, but the combustion of the mixture in the start-up condition is incomplete, The fuel economy and emission performance of the engine are all deteriorated when starting the working condition. Compared with the traditional engine, the present invention has a combustion mode corresponding to the starting working condition when starting, that is, the A-type combustion mode. The specific implementation method is: the engine is alone Use fuel A, start to supply fuel A to the cylinder during the intake stroke, so that a relatively uniform mixture of fuel A and air is formed in the cylinder, and inject fuel A into the cylinder again at the end of the compression stroke, so that it forms a local relatively small gas near the spark plug. Rich mixture. Because fuel A has low ignition energy, fast flame propagation speed, and short combustion duration, the engine can be started in a short time and the engine warm-up process can be completed quickly. When the temperature of the engine cooling water reaches the normal operating temperature of the engine, gradually add fuel B while reducing the supply of fuel A to ensure that the total heat release of the fuel remains unchanged. The total heat release of fuel = calorific value of fuel A * mass of fuel A + calorific value of fuel B * mass of fuel B. According to the simulated control parameters, the excess air coefficient of the fuel is gradually increased to make the engine idle at a larger air-fuel ratio.

2, low-load working condition (more A and less B-type combustion modes): there are two kinds of fuel stratification among the present invention, the stratification between the mixed gas formed by fuel A-air and the mixed gas formed by fuel B-air Stratification of fuel B with air. It is emphasized here that the stratification mentioned in the text refers to the stratification formed by fuel B and air unless otherwise specified. When the load is low, make the engine work in the stratified lean combustion mode. The nozzle of fuel B starts to inject during the compression stroke and implements multiple injections. The multiple injections cooperate with the gas flow to form a stratified mixture. When it is close to the compression top dead center, The nozzle of fuel A is opened, fuel A is injected, and a relatively rich mixture of fuel A and air is formed at the spark plug. The spark plug flashes to ignite it, and then ignites the lean mixture formed by fuel B and air to make the engine run normally. Due to the stratified combustion of the engine and the air layer near the engine cylinder wall, the heat transfer loss of the engine is reduced, and the thermal efficiency of the engine is improved.

3. Heavy load condition (less A and more B-type combustion mode): under heavy load, according to the signal of the accelerator pedal of the engine, the signal of the accelerator pedal gradually increases and finally stabilizes, and the engine needs a larger torque output. As the engine torque demand continues to increase, the fuel supply system gradually increases the fuel B with high net energy density, while reducing the supply of fuel A to meet the engine torque demand. The specific implementation method is to start injecting fuel B at the beginning of the intake when the engine torque requirement is met, increase the injection pulse width and injection pressure to form a uniform and rich mixture with air, and gradually reduce the fuel A. During this process, the air-fuel ratio of the mixture should be kept constant.

4. Rapid acceleration working condition (multi-A and multiple B-type combustion modes): When the engine needs to accelerate rapidly, not only large torque but also high rotational speed are required. According to the engine accelerator pedal signal, the engine accelerator pedal signal increases instantaneously. At this time, to meet the engine's rapidly increasing demand for torque and speed, it is necessary to supply the engine with a mixture with a short combustion cycle, that is, a power mixture. The specific implementation method is that the engine fuel supply system supplies fuel B with high net energy density to the engine and also needs to supply fuel A with fast combustion speed to the engine. Injection of fuel B in the intake stroke of the engine is the same as the implementation method of heavy load, and realizes high-pressure injection. At the same time, the fuel injection pulse width is increased, the difference is that more fuel A is injected when the compression is close to the top dead center, so that the combustion cycle of the mixture is the shortest, the output torque and speed of the engine increase rapidly, and the rapid acceleration of the engine is realized.

Description of drawings

Fig. 1 is the overall mechanism diagram of the dual-gas fuel combustion and control device for in-cylinder direct injection.

Fig. 2 is a cross-sectional view of the cylinder head of the direct injection dual gas fuel combustion and control device in the cylinder.

Fig. 3 shows the signals received and instructions issued by the electronic control power supply of the direct injection dual gas fuel combustion and control device in the cylinder.

Fig. 4 is a schematic diagram of the fuel injection of the direct injection dual gas fuel combustion and control device in the cylinder.

Fig. 5 is a control flow chart of the in-cylinder direct injection dual gas fuel combustion and control device.

In the figure: 1 Engine body, 2 Fuel A storage tank, 3 Fuel B storage tank, 4 Exhaust gas turbocharger, 5 Electronic control unit, 6 Three-way catalytic converter, 7 Pressure reducing valve, 8 Pressure gauge, 9 Fuel A nozzle, 10 pressure reducing valve, 11 pressure gauge, 12 fuel B nozzle, 13 exhaust manifold, 14 EGR valve, 15 intake pipe, 16 spark plug, 17 fuel B high-pressure gas rail, 18 fuel A high-pressure gas rail, 19 battery, 20 Fuel A leakage alarm device, 21 Fuel B leakage alarm device

The specific implementation manners of the present invention will be further described below in conjunction with the embodiments shown in the accompanying drawings.

Fig. 1 is an in-cylinder direct injection dual gas fuel ignition type combustion and control device, which consists of an engine body 1, a fuel A storage tank 2, a fuel B storage tank 3, an exhaust gas turbocharger 4, an electronic control unit 5, a three-effect Catalytic converter 6, pressure reducing valve 7, pressure gauge 8, fuel A nozzle 9, pressure reducing valve 10, pressure gauge 11, fuel B nozzle 12, exhaust manifold 13, EGR valve 14, intake pipe 15, spark plug 16 , Fuel B high-pressure gas rail 17, fuel A high-pressure gas rail 18, storage battery 19, fuel A leakage alarm device 20, fuel B leakage alarm device 21 and other components. The gas fuel A is connected to the high-pressure gas rail 9 of fuel A through the pressure reducing valve 7 and the pressure gauge 8, and the high-pressure gas rail is connected to the nozzle of the fuel A, and the fuel B is connected to the high-pressure gas rail 17 of the fuel B through the pressure reducing valve 10, the pressure gauge 11 The high-pressure gas rail 17 of fuel B is connected with the nozzle 12 of fuel B. Both nozzles inject fuel directly into the engine cylinder, forming the fuel supply system of the invention. The fuel supply system also includes alarms 20, 21 for fuel leaks. The exhaust manifold 13 of the engine is connected with the supercharger 4 to supercharge the intake air of the engine and form the supercharging system of the device. The EGR valve 14 connects the exhaust pipe 13 and the intake pipe 15 of the engine to form the EGR system of the device. The three-way catalytic converter 6 is connected to the exhaust manifold 13 of the engine, installed behind the supercharger 4, and processes the exhaust gas of the engine to form a refitted post-treatment system.

Figure 2 is a cross-sectional view of the cylinder head of the direct injection dual gas fuel combustion and control device. From the figure, it can be seen that the nozzle 9 of fuel A, the nozzle 12 of fuel B and the position projection of spark plug 16 on the horizontal plane are matched with Figure 4 The spatial positional relationship of the three parts can be determined. Based on this, it can be judged whether the mechanical strength of the engine cylinder head meets the requirements through finite element analysis and theoretical calculation.

Figure 3 shows the signal processing of the electronic control unit of the engine. The receiving end receives the engine operating condition signals: accelerator pedal position signal, engine speed signal, crankshaft angle signal, top dead center position signal, lubricating oil pressure signal, lubricating oil temperature signal, Cooling water temperature signal, intake air temperature and pressure signal, oxygen concentration signal in exhaust gas, knock signal, dual fuel temperature and pressure signal. The output end is connected with the fuel A nozzle 9, the fuel B nozzle 12 and the spark plug 16, and sends instructions to the actuator to realize the injection of dual fuel and the flashover of the spark plug.

Fig. 4 is the direct injection dual gas fuel combustion and control device in the cylinder, so that both fuels can realize the direct injection in the cylinder of the engine, and the positions of the fuel injectors and spark plugs of fuel A and B are designed, and the nozzle of fuel A is 9 It is at an angle of 35 degrees to the axis of the cylinder, the nozzle 12 of fuel B is at an angle of 50 degrees to the axis of the cylinder, and the angle of the spark plug 16 is at 25 degrees to the axis of the cylinder. The ignited mixture enables fuel B to form a stratified mixture under some operating conditions. This invention is a gas dual-fuel stratified combustion device, so the throttle valve of the traditional gasoline engine is canceled. Compared with the traditional stratified lean-burn engine, it not only reduces the throttling loss of the engine at high load, but also reduces the throttle loss of the engine when the engine is running. The working conditions can reduce the throttling loss of the engine, increase the intake air volume, reduce the heat transfer loss of the engine, and further improve the fuel economy of the engine. The engine can work under a larger compression ratio after lean combustion, so the compression ratio of the engine is designed to be 12, so that the thermal efficiency of the engine can be further improved.

Figure 5 is the control flow chart of the direct injection dual gas fuel combustion and control device in the cylinder. The engine operation must first judge the engine operation mode according to the operation parameters (mainly the accelerator pedal position signal) received by the engine ECU. The mode controls the engine differently, selects the combustion mode of the engine, and ensures the real-time control of the engine. Ensure that the engine torque output value meets the torque demand, and then enable the engine to achieve real-time relatively optimal control, so that the engine's economy, power, and emissions are relatively good. Each operating condition of the engine corresponds to the corresponding simulated map, and the control parameters closest to the current working state of the engine are found from the map, and then the engine is controlled. Specific implementation route: determine the operating conditions of the engine by the operating parameters of the engine - the combustion mode corresponding to the operating conditions - the relative optimal control of the combustion mode.

Claims (6)

1. the two gaseous fuel Spark ignition type burning of in-cylinder direct injection and control gear, it is characterized in that, it is made up of motor (1), exhaust-gas turbocharger (14), double fuel storage tank (2) (3), three way catalytic converter (6), EGR valve (14), electric control device (5); Double fuel storage tank (2) (3) are connected with respective nozzle (9) (12) respectively through reduction valve (7) (10), two kinds of fuel all adopt the in-cylinder direct injection of motor, exhaust-gas turbocharger (4) is connected with the exhaust manifold (13) of motor, carries out supercharging to the air inlet of motor; EGR valve (14) is connected with suction tude (15) with waste pipe (13), waste gas enters pressurized machine (4) with fresh air, electric control device (5) receives the various CRANK PULSES of motor, control the device such as oil sprayer (9) (12), spark plug (16), pressurized machine (4), EGR valve (14) of duel fuel engine

This invention also eliminates the closure of conventional point combustion engine, reduces the restriction loss of motor, improves charging efficiency.

2. the two gaseous fuel Spark ignition type burning of a kind of in-cylinder direct injection according to claim 1 and control gear, it is characterized in that, fuel in above-mentioned double fuel storage tank nonspecific two kinds of fuel, the velocity of propagation of flame of described fuel A is higher than fuel B (velocity of propagation of flame of fuel A preferably fuel B velocity of propagation of flame more than three times), the ignition energy of fuel A will lower than the ignition energy of fuel B, and the octane value of fuel A wants high; The octane value of described fuel B wants high, and the net energy density of fuel B is wanted high (should higher than the net energy density of fuel A).

3. the two gaseous fuel Spark ignition type burning of a kind of in-cylinder direct injection according to claim 1 and control gear, it is characterized in that, two kinds of fuel all adopts the direct injection in cylinder, and is engraved in the profile error under Under Different Work Condition of Engine when realizing time for spraying, the time for spraying of fuel B, the time of ignition these three of fuel A.

4. the two gaseous fuel Spark ignition type burning of a kind of in-cylinder direct injection according to claim 1 and control gear, it is characterized in that, a kind of oil sprayer of fuel near spark plug, the special shape of fitting piston, localized rich district can be formed, to realize reliable igniting near spark plug; Another kind of fuel can form rarer mixed gas with air, realizes the overall lean-burn of motor, and can realize the conversion of multiple combustion mode.

5. the two gaseous fuel Spark ignition type burning of a kind of in-cylinder direct injection according to right 1 and control gear, it is characterized in that, this device also eliminates the closure of conventional point combustion engine, decreases the pumping loss in ignition internal combustion engine intake process, improves charging efficiency.

6. the compression ratio of motor is designed to 12 by the present invention, slightly higher than the compression ratio of conventional gasoline machine, this motor is gas lean-combustion engine, and tendency to detonate reduces, and the compression ratio improving motor is conducive to improving the power character of motor and improving the Economy of motor further.