Ship-type piston combustion chamber for port injection methanol engine and design method

Abstract

The application provides a boat-shaped piston combustion chamber for a port-injection methanol engine and a design method, wherein the bottom of the inner cavity of the combustion chamber is concave downward to form an arc structure; the top of the arc structure is provided with a piston combustion chamber profile opening, the piston combustion chamber profile opening is located below the piston, and the piston combustion chamber profile opening is smaller than the diameter of the piston; the bottom section of the inner cavity of the combustion chamber comprises two circular arcs, and the joint of the two circular arcs is smoothly connected. The application has the beneficial effects that: the bottom of the combustion chamber is arranged in an arc shape, the mixed gas passes through the arc-shaped bottom of the combustion chamber to form a good tumble flow, and the uniformity of the oil-gas mixture is accelerated, so that the technical effect that the air and the methanol in the combustion chamber are uniformly mixed is achieved; a strong tumble flow is generated in the combustion chamber, the air flow movement and the oil-gas mixture are accelerated, the scavenging effect is improved, and the residual exhaust gas in the cylinder is reduced; when the piston runs to the vicinity of the top dead center, the oil-gas mixture is completed, the mixed gas moves to the vicinity of the spark plug, the spark plug generates an arc ignition, the mixed gas is ignited, and the utilization rate of the methanol is improved.

Description

Technical Field

[0001] This invention belongs to the field of piston combustion chambers for methanol engines, and particularly relates to a ship-shaped piston combustion chamber and its design method for a port-injected methanol engine. Background Technology

[0002] With the gradual implementation of the national dual-carbon policy, my country's energy structure has undergone significant changes. Methanol fuel, with its advantages of large production volume, ample reserves, and low emissions, is gradually becoming the highest-quality new energy fuel besides natural gas. Currently, engines using traditional fuels (gasoline and diesel) face the dilemma of upgraded emission regulations and equipment that does not meet existing requirements. Redesigning new energy fuel engines is costly, time-consuming, and has a high return on investment. Therefore, using new energy fuels in traditional engines is a faster and more effective approach.

[0003] Traditional gasoline engines burning methanol require no special modification, as their combustion chamber shape is sufficient for the air-fuel mixture requirements. However, when traditional diesel engines burn methanol, especially when converted into spark-ignition port-injection methanol engines, their combustion chamber shape cannot meet the air-fuel mixture requirements, resulting in low engine power output and increased methanol consumption. Therefore, a dedicated piston combustion chamber needs to be designed for this type of engine.

[0004] Figure 1 This study examines the fuel-air mixture and fuel-air movement near top dead center when methanol is injected into a conventional diesel engine using a conventional piston combustion chamber (ω-type) intake manifold.

[0005] As shown in the diagram, the methanol injected into the intake manifold enters the cylinder along with the air. Due to the limitations of the traditional piston combustion chamber shape, good airflow is not generated during the piston's upward movement, resulting in poor tumble flow, uneven fuel-air mixing, and low overall space utilization. When the piston reaches near top dead center, the tumble flow essentially disappears, and the airflow direction is inconsistent, failing to flow towards the spark plug. This leads to ignition difficulties, low fuel efficiency, high methanol consumption, and ultimately, low power output. Summary of the Invention

[0006] In view of this, the present invention aims to provide a ship-shaped piston combustion chamber and design method for a port-injected methanol engine, which has solved at least one of the problems in the background art.

[0007] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0008] The combustion chamber of the intake manifold injection methanol engine uses a boat-shaped piston with the bottom of the combustion chamber recessed downward to form an arc-shaped structure.

[0009] The top of the arc-shaped structure has a piston combustion chamber opening, which is located below the piston and is smaller than the piston diameter.

[0010] The bottom cross-section of the combustion chamber consists of two circular arcs, which are smoothly connected at the junction.

[0011] Furthermore, the arc-shaped structure is an asymmetrical structure, and the bottom cross section of the combustion chamber is composed of two eccentric arcs, namely the near-eccentric arc and the far-eccentric arc.

[0012] The center of the arc near the eccentric end and the center of the arc far from the eccentric end are coaxial but not at the same point.

[0013] Furthermore, it includes a proximal eccentric lip and a distal eccentric lip, wherein the height of the proximal eccentric lip is greater than the height of the distal eccentric lip.

[0014] Furthermore, there is an eccentricity between the center of the near-eccentric end arc and the center of the far-eccentric end arc, and the eccentricity is less than half of the piston combustion chamber opening.

[0015] Furthermore, the piston combustion chamber depth is located at the intersection of the near-eccentric end and the far-eccentric end.

[0016] Furthermore, the arc-shaped structure is a symmetrical structure, and the two arc segments are concentric arcs.

[0017] Furthermore, the axis of the center of the arc at the bottom of the combustion chamber coincides with the center line of the piston.

[0018] Compared with the prior art, the boat-shaped piston combustion chamber and design method for the intake manifold injection methanol engine described in this invention have the following advantages:

[0019] The bottom of the combustion chamber is designed in an arc shape, which allows the air-fuel mixture to form a good tumble flow, accelerating the uniformity of the air-fuel mixture. This achieves the technical effect of uniformly mixing the air and methanol entering the combustion chamber. The strong tumble flow generated in the combustion chamber accelerates the airflow and air-fuel mixture, while improving the scavenging effect and reducing residual exhaust gas in the cylinder. When the piston reaches near top dead center, the air-fuel mixture is complete. The mixture moves towards the spark plug, where it generates an electric arc to ignite the mixture, improving methanol utilization, increasing power output, reducing methanol consumption, and reducing emissions, in line with the national "dual carbon" policy. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0021] Figure 1 This is a schematic diagram of the airflow movement when methanol is injected through a conventional piston profile (ω-type) intake manifold;

[0022] Figure 2 This is a schematic diagram of the asymmetric combustion chamber structure of the present invention;

[0023] Figure 3 This is a schematic diagram of the installation and flow of the asymmetric combustion chamber piston and cylinder head of the present invention;

[0024] Figure 4 This is a top view of the asymmetric combustion chamber of the present invention;

[0025] Figure 5 This is a left view of the asymmetric combustion chamber of the present invention;

[0026] Figure 6 This is a right view of the asymmetric combustion chamber of the present invention;

[0027] Figure 7 This is a schematic diagram of the symmetrical combustion chamber structure of the present invention;

[0028] Figure 8 This is a top view of the symmetrical combustion chamber of the present invention;

[0029] Figure 9 This is a first left view of the symmetrical combustion chamber of the present invention;

[0030] Figure 10 This is a second left view of the symmetrical combustion chamber of the present invention;

[0031] Figure 11 This is a three-dimensional schematic diagram of the asymmetric combustion chamber structure of the present invention;

[0032] Figure 12 This is a three-dimensional schematic diagram of the symmetrical combustion chamber structure of the present invention.

[0033] Explanation of reference numerals in the attached figures:

[0034] 1-Piston combustion chamber opening; 2-Piston combustion chamber depth; 3-Height of the near-eccentric end combustion chamber lip; 4-Height of the far-eccentric end combustion chamber lip; 5-Piston combustion chamber eccentricity; 6-Near-eccentric end arc; 7-Center of the near-eccentric end arc; 8-Far-eccentric end arc; 9-Center of the far-eccentric end arc. Detailed Implementation

[0035] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0036] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0037] The following sections will elaborate on this design using both asymmetric and symmetric combustion chamber structures:

[0038] Asymmetric combustion chamber structure: Figure 2 The diagram provided illustrates the structure of this invention, which includes a piston combustion chamber opening 1, a piston combustion chamber depth 2, a near-eccentric end combustion chamber lip height 3, a far-eccentric end combustion chamber lip height 4, a piston combustion chamber eccentricity 5, a near-eccentric end arc 6 and its corresponding center 7, and a far-eccentric end arc 8 and its corresponding center 9. These nine parameters constitute an asymmetric boat-shaped combustion chamber. Due to the presence of the eccentric shaft and the asymmetry of its left and right arcs about the eccentric shaft, with the centers being coaxial but not concentric, this combustion chamber cannot be generated through conventional rotation but can only be generated through cutting.

[0039] The piston combustion chamber's installation position relative to the cylinder head and the airflow movement within the cylinder are as follows: Figure 3 As shown.

[0040] When the air-methanol mixture enters the cylinder, the shape of the piston combustion chamber creates a strong tumble flow, which accelerates the airflow and fuel-air mixing, while also improving the scavenging effect and reducing residual exhaust gas in the cylinder. When the piston reaches near top dead center, the fuel-air mixture is complete, and the mixture moves towards the spark plug. The spark plug generates an electric arc to ignite the mixture.

[0041] A preferred embodiment of the present invention is to set the bottom of the piston combustion chamber in an arc shape, so that the mixture forms a good tumble flow through the bottom of the arc-shaped combustion chamber, which accelerates the uniformity of oil-gas mixing, so as to achieve the technical effect of uniform mixing of air and methanol entering the combustion chamber.

[0042] A preferred embodiment of the present invention is to divide the bottom arc of the combustion chamber into two parts by an eccentricity. The lowest point of the combustion chamber is located near the eccentric end, with a small radius of curvature at the near eccentric end and a large radius of curvature at the far eccentric end. The near eccentric end of the combustion chamber is installed below the intake manifold, and the far eccentric end is installed above the exhaust manifold. This combustion chamber design and its installation method with the cylinder head ensure that air and methanol can mix for a longer period of time during the intake phase, and the mixture can form a strong scavenging flow. On the other hand, this design can ensure the scavenging intensity and reduce the amount of residual exhaust gas in the cylinder, thereby achieving the purpose of generating a strong scavenging flow, accelerating fuel-air mixing, and enhancing the scavenging effect.

[0043] The piston combustion chamber opening should be smaller than the piston diameter.

[0044] The height of the near-eccentric end lip should be greater than the height of the far-eccentric end lip.

[0045] The center of the near-eccentric end arc and the center of the far-eccentric end arc are collinear and located on the eccentric axis generated by the eccentricity.

[0046] The eccentricity should be less than half the diameter of the piston combustion chamber opening.

[0047] The piston combustion chamber depth is located at the intersection of the near-eccentric end and the far-eccentric end.

[0048] The piston combustion chamber is smoothly connected to its various parts.

[0049] In the specific implementation process, this scheme is as follows: an asymmetric boat-shaped piston combustion chamber and its design method for a compression-ignition diesel engine converted to a spark-ignition intake port injection methanol engine. It includes the piston combustion chamber opening 1, piston combustion chamber depth 2, near-eccentric end combustion chamber lip height 3, far-eccentric end combustion chamber lip height 4, piston combustion chamber eccentricity 5, near-eccentric end arc 6 and its corresponding center 7, and far-eccentric end arc 8 and its corresponding center 9. These nine parameters constitute the asymmetric boat-shaped combustion chamber. Due to the existence of the eccentric shaft and the asymmetry of its left and right arcs about the eccentric shaft, and the coaxial but not concurrent centers, this combustion chamber cannot be generated by traditional rotation but only by cutting.

[0050] The piston combustion chamber opening should be smaller than the piston diameter.

[0051] The height of the near-eccentric end lip should be greater than the height of the far-eccentric end lip.

[0052] The center of the near-eccentric end arc and the center of the far-eccentric end arc are collinear and located on the eccentric axis generated by the eccentricity.

[0053] The eccentricity should be less than half the diameter of the piston combustion chamber opening.

[0054] The piston combustion chamber depth is located at the intersection of the near-eccentric end and the far-eccentric end.

[0055] The piston combustion chamber is smoothly connected to its various parts.

[0056] By setting an eccentricity of 5 in the piston combustion chamber and two arcs 6 and 8 at the bottom of the combustion chamber, when the air-methanol mixture enters the cylinder, a strong tumble flow is generated in the combustion chamber due to the shape of the piston combustion chamber, which accelerates the airflow and fuel-air mixing, while improving the scavenging effect and reducing residual exhaust gas in the cylinder. When the piston moves to near the top dead center, the fuel-air mixing is completed, and the mixture moves towards the spark plug. The spark plug generates an electric arc to ignite the mixture, improving methanol utilization, increasing power output, reducing methanol consumption, and reducing emissions, in line with the national "dual carbon" policy.

[0057] Compared to the asymmetrical combustion chamber structure, the arc structure of the symmetrical combustion chamber is symmetrical, with the two arcs being concentric.

[0058] Those skilled in the art will recognize that the units and method steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0059] In the several embodiments provided in this application, it should be understood that the disclosed methods and systems can be implemented in other ways. For example, the division of units described above is merely a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. The aforementioned units may or may not be physically separated. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the embodiments of the present invention according to actual needs.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A boat-shaped piston combustion chamber for a port-injected methanol engine, characterized in that: The bottom of the combustion chamber is recessed downwards to form an arc-shaped structure; The top of the arc-shaped structure has a piston combustion chamber opening, which is located below the piston and is smaller than the piston diameter. The bottom cross-section of the combustion chamber includes two circular arcs, and the two circular arcs are smoothly connected at the junction. The arc-shaped structure is an asymmetrical structure. The bottom cross section of the combustion chamber is composed of two eccentric arcs, namely the near-eccentric arc and the far-eccentric arc. The center of the arc near the eccentric end and the center of the arc far from the eccentric end are coaxial but not at the same point; include The proximal eccentric end lip and the distal eccentric end lip, wherein the height of the proximal eccentric end lip is greater than the height of the distal eccentric end lip; The piston combustion chamber depth is located at the intersection of the near-eccentric end arc and the far-eccentric end arc; The near-eccentric end arc of the combustion chamber is installed below the intake manifold, and the far-eccentric end arc is installed above the exhaust manifold. There is an eccentricity between the axis containing the center of the arc near the eccentric end and the center of the arc far from the eccentric end and the piston centerline. The eccentricity is less than half of the piston combustion chamber opening.

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