阅读说明：本技术 一种低成本重油发动机冷启动结构与方法 (Low-cost heavy oil engine cold start structure and method ) 是由 赵华 于 2021-09-30 设计创作，主要内容包括：本发明公开了一种低成本重油发动机冷启动结构与方法,结构包括连通安装于发动机气缸的混合气电磁阀,与混合气电磁阀连通的燃油电磁阀,以及通过两个空气单向电磁阀与混合气电磁阀连通的气罐。方法包括以下步骤：步骤1启动准备阶段：令发动机倒拖运转,使气缸内的空气压入至气罐中；步骤2、启动阶段：使燃油通过燃油电磁阀、气罐内的空气通过空气单向电磁阀分别进入混合气电磁阀；步骤3、稳定运行阶段：控制混合气电磁阀导通,使混合气电磁阀中混合后的空气、燃油喷射至发动机气缸的燃烧室内。本发明具有易用性好、成本低优点。(The invention discloses a cold start structure and a cold start method for a low-cost heavy oil engine. The method comprises the following steps: step 1 starts the preparation phase: the engine is driven to run reversely, so that the air in the air cylinder is pressed into the air tank; step 2, a starting stage: the fuel oil passes through the fuel oil electromagnetic valve, and the air in the air tank respectively enters the mixed gas electromagnetic valve through the air one-way electromagnetic valve; step 3, stable operation stage: and controlling the conduction of the mixed gas electromagnetic valve to enable the mixed air and fuel oil in the mixed gas electromagnetic valve to be injected into a combustion chamber of an engine cylinder. The invention has the advantages of good usability and low cost.)

1. A low-cost heavy oil engine cold start structure which characterized in that: including gas mixture solenoid valve, fuel solenoid valve, gas pitcher, the exit end intercommunication of gas mixture solenoid valve is installed in engine cylinder's combustion chamber, and the gas mixture solenoid valve has two entrance points, an entrance point of gas mixture solenoid valve with the exit end intercommunication of fuel solenoid valve, the entrance point and the outside fuel source intercommunication of fuel solenoid valve, another entrance point of gas mixture solenoid valve through two parallelly connected air one-way solenoid valve with the gas pitcher intercommunication, wherein first air one-way solenoid valve switches on the direction and switches on to the gas mixture solenoid valve for following the gas pitcher, and second air one-way solenoid valve switches on the direction and switches on to the gas pitcher for following the gas mixture solenoid valve.

2. A low-cost heavy oil engine cold start structure as claimed in claim 1, wherein: the capacity of the air tank is 1/3-1/2 of the engine displacement.

3. A low-cost heavy oil engine cold start structure as claimed in claim 1, wherein: the mixed gas electromagnetic valve, the fuel oil electromagnetic valve and the two air one-way electromagnetic valves are respectively controlled and connected with the controller ECU.

4. A low-cost heavy oil engine cold start structure as set forth in claim 3, wherein: and the air tank is provided with an air pressure sensor, and the air pressure sensor is in signal transmission connection with the controller ECU.

5. A cold start method of a low-cost heavy oil engine based on the cold start structure of any one of claims 1 to 4, characterized in that: the method comprises the following steps:

step 1, a starting preparation stage:

the controller ECU controls the conduction of the second air one-way electromagnetic valve and enables the engine to drag and run backwards, so that the piston in the cylinder of the engine presses the air in the cylinder into the air tank through the mixed air electromagnetic valve and the second air one-way electromagnetic valve for many times;

step 2, a starting stage:

the controller ECU controls the second air one-way electromagnetic valve to stop conducting, and controls the fuel oil electromagnetic valve and the first air one-way electromagnetic valve to conduct, so that fuel oil passes through the fuel oil electromagnetic valve, and air in the air tank respectively enters the mixed gas electromagnetic valve through the first air one-way electromagnetic valve to be mixed;

step 3, stable operation stage:

the controller ECU controls the first air one-way electromagnetic valve to stop conducting, and controls the mixed gas electromagnetic valve to conduct, so that the mixed air and the fuel oil in the mixed gas electromagnetic valve are injected into a combustion chamber of an engine cylinder.

6. A low-cost heavy oil engine cold start method as claimed in claim 5, wherein: in the step 3, the controller ECU compares the air pressure in the air tank with a preset first air pressure threshold value, and if the air pressure in the air tank is smaller than the preset first air pressure threshold value, the controller ECU controls the first air one-way electromagnetic valve to stop conducting; and if the air pressure in the air tank is greater than a preset first air pressure threshold value, the controller ECU controls a first air one-way electromagnetic valve to be kept conducted.

7. A low-cost heavy oil engine cold start method as claimed in claim 5, wherein: and when the next cold start is carried out, firstly, comparing the air pressure in the air tank with a preset second air pressure threshold value by the controller ECU, and if the air pressure in the air tank is greater than the preset second air pressure threshold value, skipping the step 1 and directly carrying out cold start according to the steps 2 and 3.

Technical Field

The invention relates to the field of cold start of engines, in particular to a cold start structure and method of a low-cost heavy oil engine.

Background

For small engines, the use of heavy oil (including jet fuel, light diesel) fuels has obvious advantages: the heavy oil has proper density, high heat value, good combustion performance, rapid, stable, continuous and complete combustion, small combustion area, little carbon deposition and difficult coking; the low-temperature fluidity is good, and the requirements of cold low-temperature areas and high altitude on the fluidity of oil products can be met; the thermal stability and the anti-oxidation stability are good; the cleanliness is high, and the corrosion to machinery is small; the heavy oil has high ignition point and is not easy to evaporate, which is beneficial to transportation and safety protection of the fuel; the high fuel efficiency can save fuel and transportation cost, prolong the service time of power equipment and reduce the carbon emission of the power equipment; the high energy density contributes to a lighter weight and smaller volume design, further improving the service time of the power plant and the capacity of the available work.

When a heavy oil engine works, fuel is sprayed into a mist with very fine granularity through a nozzle to be fully mixed with air, so that a good combustion effect is achieved. The quality of the atomized fuel and air mixture is critical to power, economy, and emissions. The heavy oil fuel has the characteristics of poor atomization effect of the heavy oil, influences the combustion effect and even causes difficulty in cold start of the engine.

At present, in order to solve the problems existing in the cold start of the heavy oil engine, the heavy oil atomization and combustion improvement mode of the heavy oil piston engine has the following technical routes:

1) air inlet electric spray and auxiliary preheating: most of two-stroke piston engines adopt a carburetor oil supply mode, and the reliable atomization and reasonable combustion of heavy oil are difficult to guarantee by directly adopting the existing carburetor. Therefore, the design of an air intake system, a carburetor and an ignition system can be changed, meanwhile, a preheating system for assisting starting is added, and the fluidity of fuel is improved. In the improved mode, an accelerating tube is adopted for an air inlet system; use of an electronic fuel injection system instead of a carburetor; preheating a crankcase and a heavy oil circuit by using tail gas; reducing the compression ratio of the engine; starting to add a glow plug; the ignition energy is increased. The scheme has the advantages that the engine body is less modified, all required parts are general parts which can be purchased in large batch, the power-weight ratio is high, the overall cost is low, the reliability is high, and the localization rate is high; the disadvantage is that an electric heating preheating system is required to be added, and the starting is slow. This route is represented by the heavy oil engine scheme of 3W company in germany.

2) Mechanical compression direct injection technology: the technology is driven by an additional mechanical mechanism to complete direct injection and flow regulation of fuel oil in a cylinder, and air and the fuel oil are premixed, compressed and then injected into a combustion chamber, so that the scheme has the advantages that a heavy oil engine can be cold started without an external preheating device under the environment of-30 ℃, and the working altitude can reach 8000 m; the disadvantages are that: the mechanical jet regulating and driving device is required to be independent, the overall design is complex, the cost is high, the regulating range of a mechanical regulating system is limited, the degree of freedom and the flexibility are poor, and the application range is limited. This route is represented by the U.S. XRDi corporation heavy oil engine scheme.

3) Air-assisted injection technology: the technology uses an integrated nozzle with a Laval structure or a combination of an oil nozzle and an air tap, and adds an air pump on the engine through the transformation of the engine so as to add a low-pressure air path; the low-pressure air is used for impacting fuel particles, so that the fuel is fully atomized; and different oil beam atomization effects are obtained by adjusting the pressure and the opening time of the auxiliary air. The technical scheme has the advantages that the heavy oil engine can be started without auxiliary cold at the temperature of-30 ℃, and the oil consumption is low; the defects are that the structure is complex, and the reliability of the whole machine is lower; the number of added parts is more, and the engine is heavier, so that the power-weight ratio is lower; because the special nozzle is used, only 1-2 companies have the capacity of mass production of the air auxiliary nozzle all over the world, the cost of the whole machine is higher, the full-automatic controllability is lower, and the yield is easily controlled by people. Representative of this technical route is the AADI solution by the oratal corporation of australia.

Compared with the above 3 technical routes, the route 1 adopts heavy oil inlet channel injection (PFI), has the lowest cost, needs electric heating for auxiliary start, and has poor usability in the start process; routes 2 and 3 are a high-pressure direct injection mode and a low-pressure air-assisted direct injection mode respectively, the starting performance is good, but the cost of the engine is high, high pressure is continuously built for fuel oil through a mechanical structure in the running process of the engine, or pressure air is generated by an air pump, and the power loss is also large.

Disclosure of Invention

The invention aims to provide a low-cost heavy oil engine cold start structure and a low-cost heavy oil engine cold start method, and aims to solve the problems of poor usability and high cost of the heavy oil engine cold start in the prior art.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

the utility model provides a low-cost heavy oil engine cold start structure, includes gas mixture solenoid valve, fuel solenoid valve, gas pitcher, the exit end intercommunication of gas mixture solenoid valve is installed in engine cylinder's combustion chamber, and the gas mixture solenoid valve has two entrance points, an entrance point of gas mixture solenoid valve with fuel solenoid valve's exit end intercommunication, fuel solenoid valve's entrance point and outside fuel source intercommunication, another entrance point of gas mixture solenoid valve through two parallelly connected air one-way solenoid valve with the gas pitcher intercommunication, wherein first air one-way solenoid valve switch on the direction for switching on to the gas mixture solenoid valve from the gas pitcher, and second air one-way solenoid valve switches on the direction for switching on to the gas pitcher from the gas mixture solenoid valve.

Further, the capacity of the air tank is 1/3-1/2 of the engine displacement.

Furthermore, the mixed gas electromagnetic valve, the fuel oil electromagnetic valve and the two air one-way electromagnetic valves are respectively controlled and connected with the controller ECU.

Further, the gas tank is provided with a gas pressure sensor, and the gas pressure sensor is in signal transmission connection with the controller ECU.

A cold start method of a low-cost heavy oil engine comprises the following steps:

step 1, a starting preparation stage:

the controller ECU controls the conduction of the second air one-way electromagnetic valve and enables the engine to drag and run backwards, so that the piston in the cylinder of the engine presses the air in the cylinder into the air tank through the mixed air electromagnetic valve and the second air one-way electromagnetic valve for many times;

step 2, a starting stage:

the controller ECU controls the second air one-way electromagnetic valve to stop conducting, and controls the fuel oil electromagnetic valve and the first air one-way electromagnetic valve to conduct, so that fuel oil passes through the fuel oil electromagnetic valve, and air in the air tank respectively enters the mixed gas electromagnetic valve through the first air one-way electromagnetic valve to be mixed;

step 3, stable operation stage:

the controller ECU controls the first air one-way electromagnetic valve to stop conducting, and controls the mixed gas electromagnetic valve to conduct, so that the mixed air and the fuel oil in the mixed gas electromagnetic valve are injected into a combustion chamber of an engine cylinder.

Further, in step 3, the controller ECU compares the air pressure in the air tank with a preset first air pressure threshold, and if the air pressure in the air tank is smaller than the preset first air pressure threshold, the controller ECU controls the first air one-way electromagnetic valve to stop conducting; and if the air pressure in the air tank is greater than a preset first air pressure threshold value, the controller ECU controls a first air one-way electromagnetic valve to be kept conducted.

Further, when the next cold start is performed, the controller ECU compares the air pressure in the air tank with a preset second air pressure threshold, and if the air pressure in the air tank is greater than the preset second air pressure threshold, the step 1 is skipped, and the cold start is directly performed according to the steps 2 and 3.

The invention relates to an integrated gas-assisted direct injection nozzle for starting an engine, wherein a mixed gas battery valve, an oil nozzle electromagnetic valve and an oil-gas mixing cavity are integrated on a single nozzle unit, and an integrated gas tank is designed, so that the gas-assisted direct injection nozzle unit is more integrated, more compact and lower in cost.

The invention realizes the self supply of compressed air by matching the one-way valves on the air inlet and the air suction pipe with the switch of the mixed air electromagnetic valve, and simplifies the parts such as an air pump and the like on other air auxiliary injection system designs.

The cold start method adopts a three-section start method: a starting preparation stage, a starting stage and a stable operation stage. The starting preparation stage actually changes the engine into an air pump, and high-pressure air enters a compressed air cavity by opening a mixed air electromagnetic valve and matching with an air suction electromagnetic valve, so that compressed air is prepared for the starting stage; in the starting stage, the fuel oil is driven by compressed air to pass through the spray holes of the contraction and expansion pipe structure, so that the fuel oil droplets are crushed and atomized into spray, and combustible mixed gas is formed near the spark plug, thereby realizing the cold starting of the heavy oil; and in the stable operation stage, the gas-assisted direct injection nozzle unit is started to stop working, the engine uses the PFI nozzle to inject oil, and the engine stably operates.

Compared with the prior art, the invention provides the cold start structure and the cold start method of the heavy oil engine, which have good usability and low cost, are suitable for the engine with the discharge capacity of 50 cc-3L, the engine can be in two-stroke or four-stroke mode, the fuel comprises aviation kerosene or light diesel oil, and the cold start structure and the cold start method are suitable for the engine: general machinery, garden tools, generators, outboard engines, unmanned aerial vehicle engines, non-road engineering machinery engines and the like.

Drawings

FIG. 1 is a schematic diagram of the present invention.

Detailed Description

The invention is further illustrated with reference to the following figures and examples.

As shown in FIG. 1, the cold start structure of the low-cost heavy oil engine of the invention comprises a mixed gas electromagnetic valve 1, a fuel oil electromagnetic valve 2 and a gas tank 3, wherein an oil-gas mixing cavity 10 is arranged inside the mixed gas electromagnetic valve 1, the outlet end at the bottom of the mixed gas electromagnetic valve 1 is provided with a spray hole 14 with a convergent-divergent tube structure, the outlet end at the bottom of the mixed gas electromagnetic valve 1 is communicated and installed at the top of a combustion chamber 5 of an engine cylinder 4, a spark plug 9 is installed at the top of the combustion chamber 5, and the combustion chamber 5 of the engine cylinder 4 is also connected with an air inlet 12 through a PFI (pulse frequency injection) nozzle 11 for introducing air. The side of the mixed gas electromagnetic valve 1 is provided with two inlet ends, wherein one inlet end is used as a fuel inlet, and the other inlet end is used as an air inlet and an air outlet.

The inlet end of the fuel electromagnetic valve 2 is communicated with an external fuel source, the outlet end of the fuel electromagnetic valve 2 is communicated with a fuel inlet arranged on the mixed gas electromagnetic valve 1, and fuel provided by the external fuel source can enter the mixed gas electromagnetic valve 1 through the fuel electromagnetic valve 2. The gas-assisted direct injection nozzle unit 13 is formed by a mixed gas electromagnetic valve 1, an oil-gas mixed gas 10 in the mixed gas electromagnetic valve, a fuel oil electromagnetic valve 2 and a spray hole 14 of a convergent-divergent tube structure.

The air inlet and outlet of the mixed gas electromagnetic valve 1 are provided with a connecting pipe with a general branch structure, the connecting pipe is provided with two branch pipes, wherein a first air one-way electromagnetic valve 6.1 is communicated and connected into the first branch pipe, and a second air one-way electromagnetic valve 6.2 is communicated and connected into the second branch pipe. The air of gas mixture solenoid valve 1 is imported and exported and is connected with the total union end of connecting pipe, and two tunnel branch pipe ends communicate respectively in gas pitcher 3 in the connecting pipe, and wherein first air one-way solenoid valve 6.1 switches on the direction and switches on to gas mixture solenoid valve 1 from gas pitcher 3, and second air one-way solenoid valve 6.2 switches on the direction and switches on to gas pitcher 3 from gas mixture solenoid valve 1.

The capacity of the air tank is selected according to the displacement of the engine cylinder, and 1/3-1/2 of the displacement of the engine cylinder can be selected.

In the invention, the control ends of the mixed gas electromagnetic valve 1, the fuel oil electromagnetic valve 2 and the two air one-way electromagnetic valves 6.1 and 6.2 are respectively and electrically connected with the signal output end of the controller ECU8, the air tank 1 is provided with the air pressure sensor 7, and the air pressure sensor 7 is electrically connected with the signal input end of the controller ECU 8. Meanwhile, the controller ECU8 is also electrically connected with the first air one-way solenoid valve 6.1, the second air one-way solenoid valve 6.2, the spark plug 9, the mixed gas solenoid valve 1, the fuel solenoid valve 2 and the PFI nozzle 11 in a controlling way.

The invention relates to a cold start method of a low-cost heavy oil engine, which comprises the following three stages:

1. a start preparation stage:

the controller ECU controls the conduction of the second air one-way electromagnetic valve 6.2, and the engine is dragged backwards for 2-3 times by a starter or a hand-pulling starter, so that the compression stroke of the piston in the engine cylinder 4 reaches the vicinity of a top dead center, and the air in the cylinder 4 is pumped into the air tank 3 by the mixed gas electromagnetic valve and the second air one-way electromagnetic valve. At this time, the controller ECU determines whether the air pressure in the air tank 3 reaches a set value, and if the air pressure reaches the set value, the next stage is performed.

2. A starting stage:

the controller ECU controls the second air one-way electromagnetic valve 6.2 to stop conducting, and controls the fuel oil electromagnetic valve 2 and the first air one-way electromagnetic valve 6.1 to conduct, so that the fuel oil respectively enters the mixed gas electromagnetic valve 1 through the fuel oil electromagnetic valve 2 and the high-pressure air in the air tank 3 through the first air one-way electromagnetic valve 6.1 to be mixed.

In the starting stage and the previous starting preparation stage, the staggered conduction intervals of the first air one-way solenoid valve 6.1 and the second air one-way solenoid valve 6.2 are designed according to the starting process requirement, and are generally set to be 1-3 ms.

In the starting stage, the air pressure in the air tank 3 may be compared with a preset second air pressure threshold by the controller ECU, and if the air pressure in the air tank 3 is greater than the preset second air pressure threshold, it indicates that the air pressure remaining after the last cold start in the air tank 3 can meet the air for the cold start, at this time, the cold start is directly started from the starting stage without executing the starting preparation stage.

3. And (3) a stable operation stage:

the controller ECU controls the first air one-way electromagnetic valve 6.1 to stop conducting, and controls the mixed gas electromagnetic valve 1 to conduct, so that the mixed air and fuel oil in the mixed gas electromagnetic valve 1 are injected into a combustion chamber of an engine cylinder 4.

In step 3, the controller ECU may compare the air pressure in the air tank 3 with a preset first air pressure threshold, and if the air pressure in the air tank 3 is smaller than the preset first air pressure threshold, the controller ECU controls the first air one-way solenoid valve 6.1 to stop conducting.

If the air pressure in the air tank 3 is greater than the preset first air pressure threshold value, which indicates that the air in the air tank 3 still has enough air pressure, the controller ECU controls the first air one-way electromagnetic valve 6.1 to be kept on at the moment, so that the air in the air tank 3 enters the air cylinder 4 of the engine, and the engine obtains an approximate supercharging effect.

The embodiments of the present invention are described only for the preferred embodiments of the present invention, and not for the limitation of the concept and scope of the present invention, and various modifications and improvements made to the technical solution of the present invention by those skilled in the art without departing from the design concept of the present invention shall fall into the protection scope of the present invention, and the technical content of the present invention which is claimed is fully set forth in the claims.