Lean combustion control mode of spark ignition type diesel engine

Abstract

The invention relates to a lean burn control mode of a spark ignition type diesel engine, and relates to the technical field of engines, the used fuel is diesel oil, and the diesel oil is used as heavy oil, is weak in volatility, easy to store, high in ignition point and safer compared with gasoline, and meets the military use standard; an ignition device is reserved, and aviation kerosene and gasoline can be switched according to actual use conditions; compared with other two-stroke diesel engines, heating and preheating systems are not needed in the starting and working processes, and the fault probability of the whole machine is reduced; compared with a gasoline engine, the heat efficiency is higher, and the fuel consumption rate is lower; compared with a traditional two-stroke engine with the same displacement, the weight of the engine body is equivalent.

Description

Technical Field

[0001] The present invention relates to the technical field of engines, and in particular to a lean combustion control method for an ignition diesel engine and a diesel engine comprising the control method. Background Art

[0002] Traditional piston engines occupy a very important position in the field of small aircraft such as military and commercial drones due to their many advantages such as simple structure, small size, light weight, mature technology and easy maintenance.

[0003] Compared with the traditional four-stroke piston engine, the two-stroke piston engine has a simpler structure and a higher power-to-weight ratio, and therefore has broad application prospects in the field of small aircraft power in the future.

[0004] At present, the main power source for drones is internal combustion engines, among which gasoline engines are the main ones. As a lightweight fuel, gasoline has high energy density, unstable chemical molecules, high volatility, and is easy to ignite. It is difficult to store, requires harsh storage conditions, is flammable and explosive, and has poor safety. If used in the military, there is also the problem of the singleness of military fuel. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a lean combustion control method for an spark-ignition diesel engine.

[0006] The technical solution adopted by the present invention is mainly composed of an engine body, an electronic control system, a supercharging system, and a fuel supply system; the main components of the engine body are a cylinder body, a crankcase, a cylinder head, a throttle housing, a crankshaft, a connecting rod, and a piston; the main components of the electronic control system are an electronic control unit (ECU), a cylinder head temperature sensor, an intake air flow sensor (intake air temperature sensor, intake air pressure sensor), a crankshaft position sensor, a throttle servo motor, a throttle position sensor, a spark plug, an ignition coil, a fuel pump, an oil pump, an air nozzle, and a fuel nozzle; the supercharging system is mainly composed of a compressor and a high-pressure air pipe; the fuel supply system is mainly composed of a fuel rail housing, an air rail housing, a fuel tank, an oil inlet pipe, and an oil return pipe; the engine body is used as an installation base, and the electronic control system, the supercharging system, and the fuel supply system are installed or connected to the engine body. In the electronic control system, the air nozzle is fixed on the upper part of the cylinder body, and the air nozzle, the fuel nozzle, and the air rail housing form a mixing chamber. The compressor in the supercharging system provides a suitable compressed air pressure, and introduces the compressed air generated by the compressor into the mixing chamber through the high-pressure air pipe, and is secondary atomized with the oil mist sprayed by the fuel nozzle. The electronic control unit (ECU) in the electronic control system obtains the crankshaft position sensor signal and the throttle position sensor signal to calculate the basic injection amount, obtains the cylinder head temperature sensor signal and the intake flow sensor signal (intake temperature sensor, intake pressure sensor) to calculate the corrected injection coefficient, and calculates the compensation coefficient according to the electrical load of the engine, thereby determining the final injection pulse width to maintain the engine operation and ensure lean combustion.

[0007] Preferably, the compressed air pressure provided by the compressor in the air supply system does not change with the engine speed; Preferably, the high-pressure air pipe in the air supply system is not limited to a metal pipe, and can be a metal braided hose, a rubber hose or other sealed transmission pipeline; Preferably, the engine uses a spark plug to ignite the diesel combustible mixture injected from the air nozzle to perform work; Preferably, the engine of the present invention can be a spark ignition engine or a compression ignition engine, and can also be a two-stroke or four-stroke engine. In addition, the engine can include a dual-fluid fuel injection system or a single-fluid fuel injection system; Preferably, the method of determining the injection pulse width of the present invention includes not only the influence of the correction of the cylinder head temperature, the intake temperature and the intake pressure, but also the influence of the electrical load of the generator carried by the engine.

[0008] According to a second aspect of the present invention, there is provided an ignition-type air-injection direct injection diesel engine, comprising a two-stroke diesel engine combustion system as provided in the first aspect of the present invention.

[0009] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention provides a lean combustion control method for a spark-ignition diesel engine, wherein the fuel used is diesel. Diesel is a heavy oil with low volatility, easy storage, and high ignition point. It is safer than gasoline and meets military standards. 2. The diesel engine provided by the present invention retains the ignition device, and can switch between aviation kerosene and gasoline according to actual usage; 3. Compared with other two-stroke diesel engines, the present invention does not require a heating or preheating system during starting and operation, thus reducing the probability of complete machine failure; 4. The diesel engine provided by the present invention has higher thermal efficiency and lower fuel consumption rate compared with the gasoline engine; 5. The diesel engine provided by the present invention has a comparable engine weight to a conventional two-stroke engine of the same displacement. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 Schematic diagram of an engine system for implementing operations of the control system and method.

[0011] In the figure: 101, cylinder head; 102, cylinder block; 103, piston; 104, connecting rod; 105, crankcase; 106, crankshaft; 107, throttle housing; 201, cylinder head temperature sensor; 202, spark plug; 203, ignition coil; 204, crankshaft position sensor; 205, throttle position sensor; 206, throttle servo motor; 207, intake air flow sensor (intake air temperature sensor, intake air pressure sensor ); 208, oil pump; 209, air nozzle; 210, fuel nozzle; 211, fuel pump; 212, electronic control unit (ECU); 301, compressor; 302, high-pressure air pipe; 401, air guide housing; 402, oil pipe; 403, oil tank; 404, fuel rail housing; 405, fuel inlet pipe; 406, fuel return pipe; 407, fuel tank; 501, mixing chamber; 502, combustion chamber. Implementation

[0012] The present invention will be further described below in conjunction with the accompanying drawings.

[0013] like Figure 1As shown, a lean combustion control method for an ignition diesel engine includes an engine body, an electronic control system, a supercharging system, and a fuel supply system. The engine body is provided with a crankcase 105, a cylinder body 102, and a cylinder head 101. The air rail housing 401 of the fuel supply system is installed on the cylinder head 101, and fixes the air nozzle 209 in the electronic control system, and fixes the fuel nozzle 210 together with the fuel rail housing 404. The compressor 301 of the supercharging system is fixed on the crankcase 105, and is connected to the air rail housing 401 through a high-pressure air pipe 302. The crankshaft position sensor 204 of the electronic control system is installed on the crankcase 105, the throttle position sensor 205, the throttle servo motor 206, and the intake air flow sensor (intake air temperature sensor, intake air pressure sensor) 207 are installed on the throttle housing 107, and the cylinder head temperature sensor 201 is installed on the cylinder head. The sensors, actuators and electronic control unit ECU212 in the electronic control system are connected through a wiring harness.

[0014] In this example, when the engine is running, the piston 103 in the cylinder body reciprocates, which is converted by the connecting rod 104 into the rotational motion of the crankshaft 106. The crankshaft 106 drives the compressor 301 to operate and generate compressed air of appropriate pressure; the fuel rail housing 404, the air rail housing 401, the fuel nozzle 210, and the air nozzle 209 on the cylinder head 101 form a mixing chamber 501. The compressed air is filled into the mixing chamber 501 through the high-pressure air pipe 302, mixed with the diesel injected from the fuel nozzle 210, atomized once, and then sprayed into the combustion chamber 502 through the air nozzle 209 for secondary atomization.

[0015] In this example, after the secondary atomized mixture enters the combustion chamber 502 , the piston 103 moves upward and is compressed to generate sufficient pressure and temperature, and is ignited by the spark plug 202 .

[0016] To sum up, since the viscosity of diesel is higher than that of gasoline, its low-temperature fluidity is poor, and the atomization effect is poor under the same pressure. However, through the above-mentioned control method, the diesel is atomized twice under the appropriate pressure, so that the engine can be started and operated without adding redundant heating devices.

Claims

1. A lean burn control method for a spark-ignition diesel engine, characterized in that: Diesel is used as the engine fuel, and during operation, the excess air coefficient is greater than 1.

2. The method according to claim 1, characterized in that: The compressed air pressure provided by the compressor in the air supply system does not change with changes in engine speed.

3. The method of claim 1, wherein: The high-pressure air pipe in the air supply system is not limited to metal pipes, and can be other sealed transmission pipelines such as metal braided hoses and rubber hoses.

4. The method of claim 1, wherein: The engine uses a spark plug to ignite the diesel combustible mixture injected from the air nozzle to perform work.

5. The method of claim 1, wherein: Engine of the present invention can be a spark ignition engine or a compression ignition engine, and can also be a two-stroke and four-stroke engine. In addition, the engine can include a dual-fluid fuel injection system or a single-fluid fuel injection system.

6. According to (subject name) described in claim 1, the method of determining the injection pulse width of the present invention not only includes the correction influence of cylinder head temperature, intake temperature, and intake pressure, but also includes the influence of the electrical load of the generator carried by the engine.

7. According to the second aspect of the present invention, there is provided a spark-ignition direct injection diesel engine, comprising a two-stroke diesel engine combustion system as provided in the first aspect of the present invention.

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