Engine combustion chamber using high-activity fuel to assist ignition of low-activity fuel

Abstract

The invention discloses an engine combustion chamber using high-activity fuel to assist in igniting low-activity fuel, which is structurally characterized in that a pre-combustion chamber is formed by an inner nesting sleeve and an outer nesting sleeve, a high-activity fuel injector is mounted above the outer nesting sleeve, the inner nesting sleeve is mounted on a piston, and one or more spraying holes are formed in the circumference of the inner nesting sleeve; the high-activity fuel injector is fixedly installed in an engine cylinder cover, and the piston moves up and down to enable the inner nesting sleeve to enter the outer nesting sleeve. The low-activity fuel injector is installed in the air inlet channel, and the air inlet channel conveys low-activity fuel and air into the combustion chamber at the same time through the low-activity fuel injector. When the piston moves upwards, the fuel is compressed, the high-activity fuel in the pre-combustion chamber is deflagrated firstly, and generated flames ignite a mixture of the low-activity fuel and air through the spray holes embedded in the pre-combustion chamber. By means of the structure, the problem that high-activity fuel is not evenly distributed, low in concentration and difficult to ignite in a compression mode is solved, jet flow flames jetted by the jet holes can easily ignite low-activity fuel such as methyl alcohol and natural gas, and the replacement rate of the low-activity fuel is increased.

Description

Technical Field

[0001] The present invention belongs to the technical field of engine structures, and particularly relates to an engine combustion chamber that pre-ignites a high-activity fuel and then assists in igniting a low-activity fuel. Background Art

[0002] Transportation is a key area of fossil energy consumption and greenhouse gas emissions. High-carbon fossil fuels such as diesel, gasoline, and heavy fuel oil are the main power sources for transportation, especially for heavy vehicles and ships. In the field of internal combustion engines, how to achieve efficient and clean combustion of fuels is an urgent problem to be solved.

[0003] As a clean energy source, low-activity fuels can achieve low-carbon or even zero carbon emissions. Taking methanol fuel as an example, due to its high auto-ignition temperature, large latent heat of vaporization, fast flame propagation speed, low calorific value, etc., there are certain difficulties in directly applying it to engines. However, the application of low-activity fuels in engine combustion is still being explored in depth. Usually, high-activity carbon-containing fuels are used to ignite low-activity fuels, or a method of mixing high-activity carbon-containing fuels with low-activity fuels is adopted. However, pollutants such as carbon dioxide are still generated after combustion, which is not conducive to environmental protection. Therefore, how to widely apply low-activity fuels in the field of internal combustion engines and be directly and quickly ignited without affecting the engine performance to achieve true low-carbon or even zero carbon emissions has become an important problem to be solved at present.

[0004] For this reason, the present invention proposes an engine combustion chamber system that uses a high-activity fuel to pre-ignite and assist in igniting a low-activity fuel to overcome the current technical difficulties. Summary of the Invention

[0005] The purpose of the present invention is to provide an engine combustion chamber with low carbon emissions that quickly ignites a low-activity fuel with a high-activity fuel.

[0006] To solve the above problems, the technical solution of the engine combustion chamber that uses a high-activity fuel to assist in igniting a low-activity fuel is as follows:

[0007] The engine intake passage, intake valve, exhaust passage, exhaust valve are connected to the combustion chamber body. The pre-chamber is composed of an inner nest and an outer nest. The high-activity fuel injector is installed above the outer nest, and the inner nest is installed on the upper plane of the piston. There are 1 to several spray holes on the circumferential wall of the inner nest. The outer nest and the high-activity fuel injector are installed and fixed in the engine cylinder head. When the piston moves up and down, the inner nest enters the outer nest. When the inner nest completely enters the outer nest, the upper plane of the piston reaches the top dead center of the combustion chamber. The low-activity fuel injector is installed in the engine intake passage. The intake passage conveys the low-activity fuel and air into the combustion chamber through the low-activity fuel injector at the same time. When the piston moves upward, the high-activity fuel and the mixture of low-activity fuel and air are compressed at the same time. Because the ignition point of the high-activity fuel is lower than that of the mixture of low-activity fuel and air, the high-activity fuel in the pre-chamber burns first, and then causes the mixture of low-activity fuel and air in the combustion chamber to burn, enabling the engine to operate normally.

[0008] The high-activity fuel pre-chamber limits the diffusion space of the fuel ejected by the high-activity fuel injector.

[0009] In a further embodiment, there is one high-activity fuel injector and one low-activity fuel injector respectively, and there is at least one spray hole on the high- and low-activity fuel injectors.

[0010] An ω-shaped groove is machined in the inner cavity at the bottom of the high-activity fuel pre-chamber, which accelerates the combustion of the fuel and improves the combustion efficiency. For the high-activity fuel injector with a single spray hole, an ω1-shaped groove is adopted, and for the high-activity fuel injector with multiple spray holes, an ω2-shaped groove is adopted.

[0011] Compared with the current engine combustion chamber structure technology, the beneficial effects of the present invention are:

[0012] (1) The design of the high-activity fuel pre-chamber changes the traditional compression ignition method, solves the problem that the high-activity fuel is unevenly distributed and has a low concentration, and a large amount of high-activity fuel needs to be injected to achieve compression ignition, and improves the fuel utilization rate. The high-activity fuel is injected into the pre-chamber through the high-activity fuel injector and is compressed and burned. The flame generated after combustion is ejected through the spray hole, and the ejected flame is used to ignite the uniform mixture of low-activity fuel and air.

[0013] (2) The design of the pre-chamber limits the activity space of the high-activity fuel in the inner cavity of the combustion chamber, avoids the uneven distribution of the high-activity fuel in the combustion chamber, and ensures that the high-activity fuel can be evenly distributed and has a sufficient concentration. Only a small amount of high-activity fuel can be easily compressed and burned. The ω-shaped groove provided at the bottom of the inner cavity of the pre-chamber expands the contact area between the fuel spray and the air, which is beneficial to the combustion of the fuel.

[0014] (3) The traditional pre-chamber is always a closed space, and it is difficult to discharge the exhaust gas inside the pre-chamber, and it is difficult to control the temperature. There are certain differences in temperature, components, and concentration between each cycle during the operation of the engine. The design of the pre-chamber of the present invention solves the problems existing in the traditional pre-chamber. When the inner and outer nests are separated, the pre-chamber is open and there will be no situation of residual exhaust gas. In addition, when the piston moves near the top dead center, the exhaust gas in the pre-chamber can be further discharged through the spray holes on the side wall of the pre-chamber, which further ensures the concentration of highly reactive fuel in the pre-chamber, and at the same time ensures that a constant temperature environment is always maintained in the pre-chamber, ensuring that the working conditions of each cycle are at the same level.

[0015] (4) The size and number of the spray holes on the side wall of the pre-chamber are set according to actual needs. The flame ejected from the spray holes can ignite the low-reactivity fuel and improve the problem of low substitution rate of the low-reactivity fuel.

[0016] (5) The present invention is applicable to engines of various types and different cylinder diameters. On the basis of not considering the explosion pressure limit, the combustion thermal efficiency can be significantly improved compared with ordinary diesel engines. At the same time, the substitution rate of low-reactivity fuel is increased, and the feasibility of applying low-reactivity fuel to engines is improved, realizing true low-carbon or zero carbon emissions. Brief Description of the Drawings

[0017] Figure 1 It is a schematic diagram of the principle structure of the combustion chamber system of the present invention.

[0018] Figure 2 It is a schematic diagram of the inner and outer nested structure in the pre-chamber arranged on the engine piston.

[0019] Figure 3 It is a structural diagram of the outer nest of the present invention.

[0020] Figure 4 It is a structural diagram of the inner nest of the present invention.

[0021] Figure 5 It is a dimension diagram of the ω-shaped groove at the bottom of the pre-chamber in the embodiment of the present invention. This structural dimension is applicable when the high-reactivity fuel injector has only one spray hole.

[0022] Figure 6 It is a dimension diagram of the ω-shaped groove when the number of spray holes of the high-reactivity fuel injector in the pre-chamber in the embodiment of the present invention is greater than 1. Detailed Embodiments

[0023] The principle and structure of the present invention will be further described below with reference to the drawings and through specific embodiments. The embodiments are narrative rather than restrictive. Any further limitation or equivalent function substitution based on the technical solution of the present invention belongs to the protection scope of the present invention.

[0024] An engine combustion chamber that uses a highly reactive fuel to assist in igniting a low-reactivity fuel (such as Figure 1 ). Specifically, the engine intake passage, intake valve, exhaust passage, and exhaust valve are connected to the combustion chamber body. A pre-chamber is composed of an inner nested part 2-1 and an outer nested part 2-2. A highly reactive fuel injector 3 is installed above the outer nested part, and the inner nested part is installed on the upper plane of the piston 4 (such as Figures 2 - 4 ). One to several spray holes 2-11 are provided on the circumferential wall surface of the inner nested part. The outer nested part and the highly reactive fuel injector are installed and fixed inside the engine cylinder head. When the piston moves up and down, the inner nested part enters the outer nested part. When the inner nested part completely enters the outer nested part, the upper plane of the piston reaches the top dead center of the combustion chamber 1. A low-reactivity fuel injector 5 is installed in the engine intake passage 6, and the intake passage conveys the low-reactivity fuel and air into the combustion chamber simultaneously through the low-reactivity fuel injector. When the piston moves up, the highly reactive fuel and the mixture of low-reactivity fuel and air are compressed simultaneously. Since the ignition point of the highly reactive fuel is lower than that of the mixture of low-reactivity fuel and air, the highly reactive fuel in the pre-chamber burns first, and then through the spray holes on the inner nested part, it causes the mixture of low-reactivity fuel and air in the combustion chamber to burn, enabling the engine to operate normally.

[0025] An ω-shaped groove with concave sides and a convex middle is provided at the bottom of the inner nested part of the pre-chamber (such as Figure 5 ), and the structural dimensions of the groove are determined according to the number of spray holes of the highly reactive fuel injector. The outer diameter of the highly reactive fuel injector is smaller than the inner diameter of the inner nested part, the height of the highly reactive fuel injector is smaller than the height when the inner and outer nested parts coincide, and the highly reactive fuel injector extends into the inner nested part by 2 mm.

[0026] The center line of the pre-chamber and the center line of the combustion chamber are on the same axis.

[0027] As an embodiment, diesel is used as the highly reactive fuel; methanol is used as the low-reactivity fuel. The intake passage 6 is connected to the inner cavity of the combustion chamber through the intake valve 7. The methanol injector is installed in the intake passage. When the intake valve is opened, the methanol injector injects methanol fuel into the intake passage. The methanol fuel is fully mixed with air in the intake passage and then enters the combustion chamber through the intake valve for combustion. The exhaust passage 9 is connected to the inner cavity of the combustion chamber through the exhaust valve 8, and the exhaust gas generated by combustion is discharged through the exhaust valve and the exhaust passage. The diesel injector is installed in the outer nested part of the cylinder head to provide diesel fuel for the pre-chamber.

[0028] When the piston moves to the top (top dead center) of the combustion chamber, the outer nested part and the inner nested part form a (diesel) pre-chamber. The diesel injected by the diesel injector enters the pre-chamber and is compressed and ignited. The flame generated by combustion is sprayed into the inner cavity of the combustion chamber through the spray holes on the side wall of the inner nested part to ignite the mixture of methanol and air entering from the intake passage. The methanol injection timing is -240°CA, and the diesel injection timing is 1°CA.

[0029] The operation completely avoids the problem of uneven diesel distribution and too low concentration, which is difficult to compress and ignite. At the same time, the jet flame ejected from the injection hole can easily ignite the low-reactivity fuel methanol, improving the methanol substitution rate.

[0030] As Figure 5 , Figure 6 shown, there are differences in the structural dimensions of the ω-shaped groove at the bottom of the inner cavity of the diesel pre-chamber.

[0031] As an embodiment, when the diesel injector has only one injection hole, the structure and dimensions of the ω-shaped groove are as Figure 5 shown. β is the angle of the diesel spray, r0 is the radius of the bottom concave arc, r1 is the radius of the top concave arc, and preferably β is 15°. r1 is 15 mm, r0 is 30 mm. The inner nesting height is 30 mm, the diameter is 70 mm, the number of inner nesting injection holes is 8, the injection hole diameter is 5 mm, the outer nesting height is 30 mm, and the diameter is 71 mm.

[0032] As an embodiment, when the diesel injector has multiple injection holes, the structural dimensions of the ω-shaped groove are as Figure 6 shown. Where D0 is the outer diameter of the inner nesting, D1 is the groove opening diameter, D2 is the maximum outer diameter of the groove step part, d is the lip diameter, H1 is the depth of the ω-shaped groove, H2 is the height of the central boss, h is the lip depth, R0 is the lip arc radius, R is the bottom concave arc radius, and α is the central boss cone angle.

[0033] Preferably, D0 is 70 mm, D1 is 64 mm, D2 is 60 mm, d is 50 mm, H1 is 18 mm, H2 is 14 mm, h is 4 mm, R0 is 4 mm, R is 8 mm, and α is 150°. The inner nesting height is 30 mm, the number of inner nesting injection holes is 8, the injection hole diameter is 5 mm, the outer nesting height is 30 mm, and the diameter is 71 mm.

[0034] The experimental results show that the set structure of the diesel pre-chamber can not only meet the operation of the diesel-methanol dual-fuel compression ignition engine, but also greatly improve the combustion stability.

Claims

1. An engine combustion chamber that uses high-activity fuel to assist in igniting low-activity fuel, wherein the engine intake duct, intake valve, exhaust duct, and exhaust valve are connected to the combustion chamber body, and is characterized by: The pre-combustion chamber is formed by an inner nest (2-1) and an outer nest (2-2). A high-activity fuel injector (3) is installed above the outer nest. The inner nest is installed on the upper plane of the piston (4). One to several spray holes are arranged on the circumferential wall of the inner nest. The outer nest and the high-activity fuel injector are fixedly installed in the engine cylinder head. The inner nest enters the outer nest by moving the piston up and down. When the inner nest completely enters the outer nest, the upper plane of the piston reaches the upper dead center of the combustion chamber (1). The low-activity fuel injector (5) is installed in the engine intake passage (6). The intake passage delivers low-activity fuel and air into the combustion chamber at the same time through the low-activity fuel injector. When the piston moves upward, the high-activity fuel and the low-activity fuel and air mixture are compressed at the same time. Since the ignition point of the high-activity fuel is lower than the ignition point of the low-activity fuel and air mixture, the high-activity fuel in the pre-combustion chamber first explodes, and then causes the low-activity fuel and air mixture in the combustion chamber to explode, so that the engine can operate normally.

2. An engine combustion chamber for assisting the ignition of low-activity fuel by high-activity fuel according to claim 1, characterized in that: The nested bottom of the pre-combustion chamber is provided with an ω-shaped groove with concave sides and a convex middle, and the structural size of the groove is determined according to the number of spray holes of the high-activity fuel injector.

3. An engine combustion chamber for assisting the ignition of low-activity fuel by high-activity fuel according to claim 1, characterized in that: The outer diameter of the high-activity fuel injector is smaller than the inner diameter of the inner nest, the height of the high-activity fuel injector is smaller than the height when the inner and outer nests overlap, and the high-activity fuel injector extends into the inner nest by 2-3 mm.

4. The engine combustion chamber for assisting the ignition of low-activity fuel by high-activity fuel according to claim 1, characterized in that: The center line of the pre-combustion chamber and the center line of the combustion chamber are located on the same axis. The pre-combustion chamber is a closed space only when the upper plane of the piston reaches the top dead center of the combustion chamber, and is open in other cases.

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