A pre-combustion chamber jet-induced methanol spray diffusion combustion system and its application

Abstract

This invention relates to the field of internal combustion engine technology, and more particularly to a pre-combustion chamber jet-induced methanol spray diffusion combustion system and its application, integrated within the cylinder of an engine. It includes: a main combustion chamber for receiving methanol spray and air and completing combustion; an exhaust valve assembly disposed on the cylinder head at the top of the main combustion chamber; a main methanol injector disposed in the area between a first exhaust valve and a second exhaust valve; a first nozzle at the lower end of the main methanol injector having an upper nozzle group and a lower nozzle group arranged axially from top to bottom, the upper nozzle group being circumferentially asymmetrically distributed; an intake valve assembly disposed on the cylinder head at the top of the main combustion chamber; a pre-combustion chamber disposed in the area between a first intake valve and a second intake valve; and an auxiliary methanol injector and a spark plug spaced apart at the top of the pre-combustion chamber. The pre-combustion chamber jet-induced methanol spray diffusion combustion system and its application of this invention improve the combustion efficiency, effective thermal efficiency, and power density of methanol engines.

Description

Technical Field

[0001] This invention relates to the field of internal combustion engine technology, and in particular to a pre-combustion chamber jet-induced methanol spray diffusion combustion system and its application. Background Technology

[0002] Driven by both the global energy structure transformation and the strategic goals of "carbon peaking and carbon neutrality," the search for efficient and low-carbon alternative fuels and suitable power systems has become the core research direction in the field of internal combustion engines.

[0003] Methanol is a low-carbon alternative fuel with high energy density, easy storage and transportation. Its combustion products emit far fewer harmful pollutants (such as particulate matter and nitrogen oxides) than traditional gasoline and diesel. Especially in the context of the era of "carbon peaking" and "carbon neutrality," methanol, as a clean fuel, has broad application prospects in new energy vehicles, ships, power generation, and other fields. Therefore, conducting research on efficient and clean combustion methanol engines is of great significance.

[0004] However, some of the physicochemical properties of methanol itself pose a serious challenge to the efficient and stable combustion of engines. Due to the high ignition temperature and low cetane number of methanol (only 3-5), spark-ignition methanol engines face the problem of misfire under low load and lean combustion conditions, and also have difficulties in cold starting at low temperatures. Therefore, improving the ignition stability and combustion characteristics of the engine are the main technical problems that need to be solved for spark-ignition methanol engines.

[0005] Jet-induced combustion systems can effectively improve ignition energy and solve problems such as unstable and incomplete combustion in engines. However, existing combustion systems suffer from problems such as mismatch in the distribution of methanol and air in the cylinder, low in-cylinder air utilization, and uneven and insufficient fuel-air mixing, which restrict the improvement of combustion efficiency, effective thermal efficiency, and power density of methanol engines. Summary of the Invention

[0006] To address at least one of the aforementioned technical problems, the present invention provides a pre-combustion chamber jet-induced methanol spray diffusion combustion system and its application, thereby achieving reliable ignition of methanol spray diffusion combustion and uniform and thorough mixing of oil and gas within the combustion system, thereby improving the engine's combustion efficiency, effective thermal efficiency, and power density, while avoiding knocking.

[0007] In one aspect, the present invention provides a pre-combustion chamber jet-induced methanol spray diffusion combustion system, which is integrated into the cylinder of an engine and includes: a main combustion chamber for receiving methanol spray and air and completing combustion; an exhaust valve assembly disposed on the cylinder head at the top of the main combustion chamber, including a symmetrically arranged first exhaust valve and a second exhaust valve for discharging combustion exhaust gases from the main combustion chamber; and a main methanol injector disposed in the area between the first exhaust valve and the second exhaust valve, wherein the axis of the main methanol injector is collinear with or parallel to the axis of the cylinder; wherein the lower end of the main methanol injector... The system includes a first nozzle extending into the main combustion chamber. Along its axial direction, the first nozzle has an upper nozzle group and a lower nozzle group arranged from top to bottom. The upper nozzle group consists of multiple upper nozzles, and the lower nozzle group consists of multiple lower nozzles. The upper nozzles are asymmetrically distributed along the circumference of the first nozzle, while the lower nozzles are symmetrically distributed along the circumference of the first nozzle. Both the upper and lower nozzles communicate with the fuel passages inside the main injector. An intake valve assembly, located on the cylinder head at the top of the main combustion chamber, includes a first intake valve and a second intake valve. A pre-combustion chamber is located within the first intake... The area between the main intake valve and the second intake valve is connected to the main combustion chamber, and a jet orifice penetrating the inside and outside of the pre-combustion chamber is provided at the bottom. A secondary methanol injector is located at the top of the pre-combustion chamber with its nozzle extending into the chamber, used to inject methanol into the pre-combustion chamber. A spark plug is located at the top of the pre-combustion chamber and spaced apart from the secondary methanol injector; its electrode extends into the pre-combustion chamber to ignite the air-fuel mixture, forming a jet flame. The upper spray orifice of the main methanol injector, located on the side near the exhaust valve assembly, is defined by a cross-section passing through the central axis of the main methanol injector and perpendicular to the horizontal plane. The sum of the number of the lower layer nozzles is N1, and the sum of the number of the upper layer nozzles and the lower layer nozzles located on the side of the main injector near the intake valve assembly is N2. Taking the cross-section passing through the central axis of the main injector and perpendicular to the horizontal plane as the interface, when the piston reaches the top dead center, the volume of the area enclosed by the interface, the exhaust valve assembly, and the cylinder inner wall is V1, and the volume of the area enclosed by the interface, the intake valve assembly, and the cylinder inner wall is V2. N1, N2, V1, and V2 satisfy the relationship: N1 / N2=V1 / V2, and the range of V1 / V2 is 0.50~0.75.

[0008] In some embodiments of the present invention, the upper spray holes are asymmetrically and uniformly distributed on one side at 180° in the circumferential direction of the first nozzle; wherein the one side is the side closer to the intake valve assembly; and / or, the lower spray holes are symmetrically and uniformly distributed on one side at 360° in the circumferential direction of the first nozzle.

[0009] In some embodiments of the present invention, if the upper spray hole and the lower spray hole are respectively disposed on the interface, the upper spray hole and the lower spray hole are evenly distributed, and 0.5 are counted in N1 and N2 respectively.

[0010] In some embodiments of the present invention, the included angle α1 of the first nozzle of the lower nozzle ranges from 60° to 75°.

[0011] In some embodiments of the present invention, the included angle α2 of the second nozzle of the upper nozzle is in the range of (α1+2°)~(α1+8°); wherein α1 is the included angle of the first nozzle of the lower nozzle.

[0012] In some embodiments of the present invention, the axis of the upper spray hole is inclined outward toward the first nozzle.

[0013] In some embodiments of the invention, the axis of the lower nozzle is inclined outward toward the first nozzle.

[0014] In some embodiments of the present invention, the jet holes are uniformly distributed along the circumference of the pre-combustion chamber and the outlet of the jet holes is located entirely inside the main combustion chamber.

[0015] In another aspect, the present invention provides an application of the above-described pre-combustion chamber jet-induced methanol spray diffusion combustion system in methanol engines.

[0016] In some embodiments of the present invention, the methanol engine is a spark-ignition methanol engine.

[0017] The technical solution provided by this invention has the following advantages:

[0018] In the pre-combustion chamber jet-induced methanol spray diffusion combustion system and its application, firstly, by "differentiated distribution of the upper and lower spray holes of the main injector (i.e., the upper spray holes are asymmetrically and uniformly distributed at 180° on one side, and the lower spray holes are symmetrically and uniformly distributed at 360°)," the spatial distribution of methanol spray and air in the main combustion chamber is matched, promoting more uniform and thorough mixing of fuel and gas. Secondly, by "gradient size of the angle between the first and second spray holes (i.e., the angle between the second spray hole of the upper spray hole is greater than the angle between the first spray hole of the lower spray hole)," the methanol spray can effectively utilize the air at the far end of the main combustion chamber of the cylinder, thereby improving the utilization rate of air in the cylinder. Then, the auxiliary injector injects a mixture of methanol and air into the pre-combustion chamber, which is ignited by the spark plug and then combusted. The high-temperature, high-speed jet flame is ejected into the main combustion chamber through the pre-combustion chamber jet holes, thereby providing ignition energy far exceeding that of traditional spark plugs and achieving simultaneous ignition at multiple points, significantly improving ignition reliability. In addition, by staggering the high-heat-load exhaust valve assembly and the pre-combustion chamber, the superposition and concentration of heat loads on structural components are reduced, which helps to reduce the concentration of thermal stress in structural components and improve the reliability of structural components.

[0019] Therefore, the pre-combustion chamber jet-induced methanol spray diffusion combustion system and its application in this embodiment of the invention achieve a reasonable distribution of methanol in the cylinder, improve the air utilization rate in the cylinder, and improve the formation of the air-fuel mixture in the cylinder; by using the jet flame injected from the pre-combustion chamber, the high-pressure methanol spray in the main combustion chamber is ignited, achieving stable ignition of the spark-ignition methanol engine, and ultimately improving the performance indicators of the methanol engine. Attached Figure Description

[0020] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the structure of a pre-combustion chamber jet-induced methanol spray diffusion combustion system according to an embodiment of the present invention;

[0023] Figure 2 This is a top view of the cylinder head of a pre-combustion chamber jet-induced methanol spray diffusion combustion system according to an embodiment of the present invention;

[0024] Figure 3 This is an axial cross-sectional view of the first nozzle of the main injector of the pre-combustion chamber jet-induced methanol spray diffusion combustion system according to an embodiment of the present invention.

[0025] Figure 4 This is a schematic diagram of the structure of a pre-combustion chamber jet-induced methanol spray diffusion combustion system according to an embodiment of the present invention, with the cross-section passing through the central axis of the main methanol injector and perpendicular to the horizontal plane as the interface, and the upper spray hole located on the interface.

[0026] 1-Cylinder;

[0027] 2-Exhaust valve assembly;

[0028] 3-Intake valve assembly;

[0029] 4-Main sprayer;

[0030] 5-Pre-combustion chamber;

[0031] 6-Separation interface;

[0032] 7-Substitute alcohol injector;

[0033] 8-Spark plug;

[0034] 9-Main combustion chamber;

[0035] 10-Jet Flame;

[0036] 11-Methanol spray;

[0037] 12-Piston;

[0038] 41 - Lower spray nozzle;

[0039] 42 - Upper spray nozzle. Detailed Implementation

[0040] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0041] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.

[0042] According to an embodiment of the present invention, a pre-combustion chamber jet-induced methanol spray diffusion combustion system is provided, the schematic diagram of which is shown below. Figure 1 As shown. Figure 1 In this system, a pre-combustion chamber jet-induced methanol spray diffusion combustion system is integrated into the engine cylinder, including: a main combustion chamber for receiving methanol spray and air and completing combustion; an exhaust valve assembly located on the cylinder head at the top of the main combustion chamber, including a symmetrically arranged first exhaust valve and a second exhaust valve for discharging combustion exhaust gases from the main combustion chamber; and a main methanol injector located in the area between the first and second exhaust valves, with the axis of the main methanol injector collinear or parallel to the axis of the cylinder; wherein, the lower end of the main methanol injector is provided with a first nozzle extending into the main combustion chamber, and the first nozzle is provided with an upper nozzle group and a lower nozzle group arranged in a top-to-bottom order along its axial direction, the upper nozzle group consisting of multiple upper nozzles and the lower nozzle group consisting of multiple lower nozzles, the upper nozzles being arranged along... The first nozzle is asymmetrically distributed circumferentially, while the lower nozzle is symmetrically distributed circumferentially along the first nozzle. Both the upper and lower nozzles are connected to the fuel passage inside the main fuel injector. The intake valve assembly, located on the cylinder head at the top of the main combustion chamber, includes a first intake valve and a second intake valve. The pre-combustion chamber, located between the first and second intake valves, is connected to the main combustion chamber, and has a jet hole at its bottom that penetrates the inside and outside of the pre-combustion chamber. The auxiliary fuel injector, located at the top of the pre-combustion chamber with its nozzle extending into the pre-combustion chamber, is used to inject methanol into the pre-combustion chamber. The spark plug, located at the top of the pre-combustion chamber and spaced apart from the auxiliary fuel injector, has its electrode extending into the pre-combustion chamber to ignite the air-fuel mixture in the pre-combustion chamber, forming a jet flame.

[0043] In some embodiments of the present invention, the high-temperature, high-pressure flame in the pre-combustion chamber, under the influence of temperature and pressure differences, is injected into the main combustion chamber through the jet orifice of the pre-combustion chamber, forming a jet flame in the main combustion chamber. The formed jet flame collides with the methanol spray in the main combustion chamber, and the large amount of active substances carried in the jet flame induces the high-pressure methanol spray in the main combustion chamber to ignite, achieving a spray diffusion combustion similar to diesel fuel, thereby improving thermal efficiency and power density while avoiding knocking.

[0044] In some embodiments of the present invention, the main fuel injector and the pre-combustion chamber are both arranged in the area between the four valves (i.e., the first and second exhaust valves in the exhaust valve assembly, and the first and second intake valves in the intake valve assembly) at the center of the cylinder head. Since both the exhaust valve assembly and the pre-combustion chamber are high-heat-load areas, they are staggered, with the main fuel injector located on the side closer to the exhaust valve assembly and the pre-combustion chamber located on the side closer to the intake valve assembly.

[0045] In some embodiments of the present invention, a top view of the cylinder head of the pre-combustion chamber jet-induced methanol spray diffusion combustion system is shown below. Figure 2 As shown. Figure 2 In the cylinder 1, the main fuel injector 4 is located on the side near the exhaust valve assembly 2, and the pre-combustion chamber 5 is located on the side near the intake valve assembly 3. The interface 6 is a cross-section passing through the central axis of the main fuel injector and perpendicular to the horizontal plane.

[0046] In some embodiments of the present invention, the cross-section passing through the central axis of the main injector and perpendicular to the horizontal plane is used as the interface. The sum of the number of upper and lower injection holes on the side near the exhaust valve assembly is N1, and the sum of the number of upper and lower injection holes on the side near the intake valve assembly is N2. When the piston reaches top dead center, the volume of the area enclosed by the interface, the exhaust valve assembly, and the cylinder wall is V1, and the volume of the area enclosed by the interface, the intake valve assembly, and the cylinder wall is V2. The relationship between N1, N2, V1, and V2 needs to satisfy: N1 / N2 = V1 / V2 and the range of V1 / V2 is 0.50~0.75.

[0047] In some embodiments of the present invention, the cylinder is divided by a cross-section passing through the central axis of the main injector and perpendicular to the horizontal plane. When the piston reaches top dead center, the cylinder volume V1 is the area enclosed by the interface, the exhaust valve assembly, and the cylinder inner wall (left side of the interface); the cylinder volume V2 is the area enclosed by the interface, the intake valve assembly, and the cylinder inner wall (right side of the interface); the ratio of V1 to V2 is V1 / V2 = 39% / 61%. According to "N1 / N2=V1 / V2", the ratio of the sum of the number of upper and lower nozzles N1 on the side near the exhaust valve assembly (left side of the interface) to the number of upper and lower nozzles N2 on the side near the intake valve assembly (right side of the interface) is set as N1 / N2=4 / 6 (the specific calculation process is as follows: first, round the units digit of V1 and V2 according to the rounding rule to obtain V1 and V2 in multiples of ten; take the rounded V1 / V2 ratio as the N1 / N2 ratio).

[0048] In some embodiments of the present invention, the upper nozzle group consists of a plurality of upper nozzles, which are asymmetrically distributed on one side at 180° around the first nozzle and the axis of the upper nozzles is inclined to the outside of the first nozzle.

[0049] In some embodiments of the present invention, the lower nozzle group consists of a plurality of lower nozzles, which are symmetrically and uniformly distributed in a 360° circumferential direction around the first nozzle, and the axis of the lower nozzles is inclined to the outside of the first nozzle.

[0050] In some embodiments of the present invention, the aperture sizes of the upper and lower spray holes are exactly the same.

[0051] In some embodiments of the present invention, the included angle α1 of the first nozzle of the lower nozzle ranges from 60° to 75°, and the included angle α2 of the second nozzle of the upper nozzle ranges from (α1+2°) to (α1+8°). This gradient setting of the included angles of the second nozzle of the upper nozzle and the first nozzle of the lower nozzle allows the methanol spray from the upper nozzle to land further within the cylinder, effectively utilizing the air in the peripheral area of ​​the intake valve assembly.

[0052] In some embodiments of the present invention, the axis of the main alcohol injector 4 is the axis of the first nozzle.

[0053] In some embodiments of the present invention, the axial cross-sectional view of the first nozzle of the main injector of the pre-combustion chamber jet-induced methanol spray diffusion combustion system is shown below. Figure 3 As shown. Figure 3In the middle section, the angle between the axis of the lower spray hole 41 and the axis of the main alcohol injector 4 (i.e., the axis of the first nozzle) is the first spray hole angle α1, and the value of α1 ranges from 60° to 75°. The angle between the axis of the upper spray hole 42 and the axis of the main alcohol injector 4 (i.e., the axis of the first nozzle) is the second spray hole angle α2, and the value of α2 ranges from (α1+2°) to (α1+8°).

[0054] In some embodiments of the present invention, in the pre-combustion chamber jet-induced methanol spray diffusion combustion system, the cross-section passing through the central axis of the main methanol injector and perpendicular to the horizontal plane is used as the interface. A schematic diagram of the structure when the upper spray nozzle is located on the interface is shown below. Figure 4 As shown. Figure 4 In the main sprayer 4, the first nozzle is equipped with an upper spray hole group and a lower spray hole group. The upper spray hole group consists of 4 upper spray holes 42, and the lower spray hole group consists of 6 lower spray holes 41. The upper spray holes 42 and the lower spray holes 41 have the same diameter. The lower spray holes 41 are symmetrically and evenly distributed 6 times around the first nozzle of the main sprayer 4 in a 360° circumference. The upper spray holes 42 are asymmetrically and evenly distributed 180° on one side of the first nozzle of the main sprayer 4 in a 180° circumference. The upper spray holes 42 at 0° and 180° span the left and right sides of the interface. When counting the number of upper spray holes N1 and lower spray holes N2 on the left and right sides of the interface, 0.5 holes are counted on each side. Therefore, N1 is 3 + 0.5 + 0.5 = 4, and N2 is 5 + 0.5 + 0.5 = 6.

[0055] In some embodiments of the present invention, the included angle α1 of the first nozzle of the lower nozzle of the main sprayer is 75°, and the included angle α2 of the second nozzle of the upper nozzle is 80°.

[0056] In some embodiments of the present invention, the cylinder diameter is 300 mm.

[0057] In some embodiments of the present invention, a secondary methanol injector and a spark plug are spaced apart at the top of the pre-combustion chamber; wherein, the secondary methanol injector injects a certain amount of methanol into the pre-combustion chamber to form a mixture of a certain concentration, and the spark plug ignites the mixture to form a jet flame, which is ejected from the jet hole of the pre-combustion chamber to induce and ignite the high-pressure methanol spray in the main combustion chamber.

[0058] Example

[0059] The methanol engine using the pre-combustion chamber jet-induced methanol spray diffusion combustion system of this invention improves combustion efficiency by 5.2%, effective thermal efficiency by 6.5%, and power density by 8.8% compared to the prototype methanol engine.

[0060] The methanol engine in the pre-combustion chamber jet-induced methanol spray diffusion combustion system differs from the prototype methanol engine only in the following ways:

[0061] The methanol engine using the pre-combustion chamber jet-induced methanol spray diffusion combustion system is as follows: The pre-combustion chamber jet-induced methanol spray diffusion combustion system of this invention is applied to a 300mm diameter methanol engine employing this method. Specifically, the main injector uses the double-layer nozzles described in this invention, with four upper nozzles and six lower nozzles. The included angle α1 of the first nozzle in the lower layer is 70°, and the included angle α2 of the second nozzle in the upper layer is 74°. The ratio of the volume on the left side of the cylinder interface (i.e., the volume of the area enclosed by the interface, exhaust valve assembly, and cylinder wall) to the volume on the right side (i.e., the volume of the area enclosed by the interface, intake valve assembly, and cylinder wall) at top dead center is... V1 / V2=4 / 6. The six lower-layer nozzles are symmetrically and evenly distributed 360° around the first nozzle of the main sprayer, and none of them cross the left and right sides of the interface. Four of the lower-layer nozzles are completely located on the left side of the interface, and two of them are completely located on the right side of the interface. The four upper-layer nozzles are asymmetrically and evenly distributed 180° on each side around the first nozzle of the main sprayer, and none of them cross the left and right sides of the interface. All of them are located on the right side of the interface. The ratio of the number of upper-layer nozzles to the number of lower-layer nozzles is: N1 / N2=4 / (2+4)=4 / 6. At this time, the ratio of the number of nozzles N1 / N2 matches the ratio of the left and right volumes of the interface V1 / V2 exactly, that is: N1 / N2=V1 / V2=4 / 6.

[0062] The prototype methanol engine is a pre-combustion chamber jet-induced methanol spray diffusion combustion method with a circumferentially uniformly distributed nozzle scheme for the main methanol injector.

[0063] In summary, the pre-combustion chamber jet-induced methanol spray diffusion combustion system and its application in this embodiment of the invention improve the in-cylinder mixture formation effect of methanol engines, making the distribution of methanol in the cylinder more uniform and reasonable, the air utilization rate higher, and the fuel-air mixture more complete. When applied to a 300mm cylinder bore high-power methanol engine, this combustion system improves the combustion efficiency by 5.2%, the effective thermal efficiency by 6.5%, and the power density by 8.8%.

[0064] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0065] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A pre-combustion chamber jet-induced methanol spray diffusion combustion system, characterized in that, The pre-combustion chamber jet-induced methanol spray diffusion combustion system is integrated into the engine cylinder and includes: The main combustion chamber is used to receive methanol spray and air and complete combustion. An exhaust valve assembly is disposed on the cylinder head at the top of the main combustion chamber, including a first exhaust valve and a second exhaust valve arranged symmetrically, for discharging combustion exhaust gases from the main combustion chamber; The main fuel injector is located in the area between the first exhaust valve and the second exhaust valve, and the axis of the main fuel injector is collinear with or parallel to the axis of the cylinder. The lower end of the main injector is provided with a first nozzle extending into the main combustion chamber. The first nozzle is provided with an upper spray hole group and a lower spray hole group in a top-to-bottom order along its axial direction. The upper nozzle group consists of multiple upper nozzles, and the lower nozzle group consists of multiple lower nozzles. The upper nozzles are asymmetrically distributed along the circumference of the first nozzle, and the lower nozzles are symmetrically distributed along the circumference of the first nozzle. The upper and lower spray holes are respectively connected to the fuel passage inside the main injector; An intake valve assembly, disposed on the cylinder head at the top of the main combustion chamber, includes a first intake valve and a second intake valve; The pre-combustion chamber is located in the area between the first intake valve and the second intake valve. Its cavity is connected to the main combustion chamber, and its bottom is provided with a jet hole that penetrates the inside and outside of the pre-combustion chamber cavity. A secondary methanol injector, located at the top of the pre-combustion chamber with its nozzle extending into the pre-combustion chamber, is used to inject methanol into the pre-combustion chamber. A spark plug is disposed at the top of the pre-combustion chamber and spaced apart from the auxiliary alcohol injector. Its electrode extends into the pre-combustion chamber to ignite the gas mixture in the pre-combustion chamber to form a jet flame. Among them, the cross-section passing through the central axis of the main injector and perpendicular to the horizontal plane is used as the dividing interface. The sum of the number of upper and lower spray holes set on the side of the main injector near the exhaust valve assembly is N1, and the sum of the number of upper and lower spray holes set on the side of the main injector near the intake valve assembly is N2. Taking the cross-section that passes through the central axis of the main injector and is perpendicular to the horizontal plane as the interface, when the piston reaches the top dead center, the volume of the area enclosed by the interface, the exhaust valve assembly, and the cylinder inner wall is V1, and the volume of the area enclosed by the interface, the intake valve assembly, and the cylinder inner wall is V2. N1, N2, V1, and V2 satisfy the relationship: N1 / N2 = V1 / V2, and the range of V1 / V2 is 0.50 to 0.

75.

2. The pre-combustion chamber jet-induced methanol spray diffusion combustion system according to claim 1, characterized in that, The upper spray holes are uniformly distributed asymmetrically on one side at 180° in the circumference of the first nozzle; Wherein, the "single side" refers to the side closest to the intake valve assembly; And / or, the lower spray holes are symmetrically and uniformly distributed in the circumferential direction of the first nozzle at 360°.

3. The pre-combustion chamber jet-induced methanol spray diffusion combustion system according to claim 1, characterized in that, If the upper and lower spray holes are set on the interface, then the upper and lower spray holes are evenly distributed, with 0.5 each in N1 and N2.

4. The pre-combustion chamber jet-induced methanol spray diffusion combustion system according to claim 1, characterized in that, The included angle α1 of the first nozzle of the lower layer nozzle is in the range of 60°~75°.

5. The pre-combustion chamber jet-induced methanol spray diffusion combustion system according to claim 1, characterized in that, The included angle α2 of the second nozzle of the upper nozzle is in the range of (α1+2°)~(α1+8°); Where α1 is the included angle of the first nozzle of the lower layer nozzle.

6. The pre-combustion chamber jet-induced methanol spray diffusion combustion system according to claim 1, characterized in that, The axis of the upper spray hole is inclined to the outside of the first nozzle.

7. The pre-combustion chamber jet-induced methanol spray diffusion combustion system according to claim 1, characterized in that, The axis of the lower spray hole is inclined to the outside of the first nozzle.

8. The pre-combustion chamber jet-induced methanol spray diffusion combustion system according to claim 1, characterized in that, The jet orifices are evenly distributed along the circumference of the pre-combustion chamber, and the outlets of the jet orifices are located entirely inside the main combustion chamber.

9. The application of the pre-combustion chamber jet-induced methanol spray diffusion combustion system according to any one of claims 1 to 8 in methanol engines.

10. The application according to claim 9, characterized in that, The methanol engine is a spark-ignition methanol engine.

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