A combustion system for a large-bore high-speed diesel engine and a diesel engine

Abstract

The present invention provides a combustion system and a diesel engine for a large-bore high-speed diesel engine, including a combustion chamber and an injector. The injector includes a plurality of injection holes, and a plurality of bionic structure grooves are formed on the inner wall of the injection holes of the injector body, so that the fuel spray ejected from the injection holes is in a conical spiral shape; the main body of the inner cavity of the combustion chamber is in a ω shape, and three semi-elliptical circumferential grooves are formed on the inner wall of each pit of the ω-shaped combustion chamber; the present invention optimizes the injector structure, designs a reasonable combustion chamber structure, accelerates the fuel-air mixing, enables the fuel-air mixture to quickly enter the combustion chamber and form a swirling motion in the combustion chamber, speeds up the combustion process, improves the thermal efficiency, and can meet the high-speed requirements of large-bore diesel engines.

Description

Technical Field

[0001] The present invention relates to the technical field of diesel engines, and particularly to an injector, a combustion system of a large-bore high-speed diesel engine, and a large-bore high-speed diesel engine. Background Art

[0002] The statements in this part only present the background art related to the present invention and do not necessarily constitute the prior art.

[0003] Large-bore diesel engines have the characteristics of high power density, good reliability, and low comprehensive cost. For a long time in the past, they have been widely used in ship power or high-power construction machinery.

[0004] However, the inventor found that traditional large-bore diesel engines also have problems such as slow combustion speed and low rotational speed. As a result, the power of the diesel engine with the same cylinder diameter is relatively low. With the increasing market demand, large-bore diesel engines urgently need to increase their rotational speed to improve their power. However, when the rotational speed of a large-bore high-speed diesel engine is relatively high, the combustion cycle time is short, and the in-cylinder combustion is more incomplete, resulting in serious problems of energy consumption and pollution. Summary of the Invention

[0005] In order to solve the deficiencies of the prior art, the present invention proposes a combustion system and a diesel engine for a large-bore high-speed diesel engine, optimizes the structure of the injector, designs a reasonable combustion chamber structure, accelerates the mixing of oil and gas, enables the oil-gas mixture to quickly enter the combustion chamber and form a swirling motion in the combustion chamber, speeds up the combustion process, improves the thermal efficiency, and can meet the requirements of high-speed operation of large-bore diesel engines.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention proposes an injector.

[0008] An injector includes: an injector body, and a plurality of bionic structure grooves are formed on the inner wall of the injection hole of the injector body, so that the oil spray ejected from the injection hole is in a conical spiral shape.

[0009] As a further limitation of the first aspect of the present invention, each bionic structure groove is evenly arranged at equal intervals along the circumference of the injection hole.

[0010] As a further preference of the first aspect of the present invention, the number of bionic structure grooves is four, and the adjacent bionic structure grooves are spaced 90°.

[0011] As a further preference of the first aspect of the present invention, the number range of the injection holes is four to eight, and the diameter of the injection hole is greater than a set threshold value.

[0012] As a further preference of the first aspect of the present invention, when the number of fuel injection holes is four, the included angles of the respective fuel injection holes are 75°, 90°, 120° and 135° respectively.

[0013] As a further preference of the first aspect of the present invention, the bionic structure groove is in the shape of an unequal pitch cylindrical helix, x = 0.4cos2πt, y = 0.4sin2πt, z = 0.72t 1.5 , where t is a dimensionless number, t ∈ [0, 12], and the pitch of any point on the unequal pitch cylindrical helix groove is P, P = 1.2e 36.8z cos(4z), with the unit of mm.

[0014] In the second aspect, the present invention provides a combustion system for a large-bore high-speed diesel engine.

[0015] A combustion system for a large-bore high-speed diesel engine includes a combustion chamber and the fuel injector described in the first aspect of the present invention. The fuel injector includes a plurality of fuel injection holes;

[0016] The inner cavity body of the combustion chamber is in a ω shape. Three semi-elliptical circumferential grooves are provided on the inner wall of each pit of the ω-shaped combustion chamber. The included angles of the respective fuel injection holes are different, and the fuel injection holes are non-uniformly distributed circumferentially along the axis of the fuel injector.

[0017] As a further limitation of the second aspect of the present invention, the major axes of the three semi-elliptical circumferential grooves in the same pit are collinear, and the collinear straight line forms a set included angle with the horizontal line.

[0018] As a further preference of the second aspect of the present invention, the three semi-elliptical circumferential grooves are groove one, groove two and groove three respectively. The major axis lengths of groove one, groove two and groove three are different. Taking the major axis of groove one as the x-axis and the minor axis of groove one as the y-axis, a rectangular coordinate system is established;

[0019] The equation of the semi-ellipse of groove one is:

[0020] The equation of the semi-ellipse of groove two is:

[0021] The equation of the semi-ellipse of groove three is:

[0022] In the third aspect, the present invention provides a large-bore high-speed diesel engine, which includes the fuel injector described in the first aspect of the present invention; or, includes the combustion system of the large-bore high-speed diesel engine described in the second aspect of the present invention.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] 1. The present invention uses a large-diameter fuel injection hole engraved with a bionic structure groove, making the fuel spray ejected by the injector in a conical spiral shape. The fuel injection hole engraved with the bionic groove causes the fuel spray ejected by the injector to generate a regular rotational movement in the combustion chamber, which synergistically moves with the eddy current of the air in the combustion chamber, improving the formation speed and quality of the combustible mixed gas, accelerating the combustion speed, and improving the power performance and fuel economy of the diesel engine.

[0025] 2. The present invention adopts a multi-wave combustion chamber structure. The multi-wave combustion chamber corrects the defect of very weak air flow movement in the central area through the protrusion in the center of the pit. At the same time, the three semi-elliptical circumferential grooves adapt to the spiral fuel spray, making it difficult for a large amount of the fuel mist ejected by the injector to adhere to the inner cavity of the combustion chamber. Moreover, the incoming fuel and air can form an eddy current together in the combustion chamber, making it easier for the combustion chamber to form a uniform mixture, accelerating the combustion process, and improving the thermal efficiency.

[0026] Advantages of additional aspects of the present invention will be partly given in the following description, partly will become obvious from the following description, or will be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The schematic diagrams in the specification forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0028] Figure 1 Schematic diagram of the fuel injection hole provided for Embodiment 1 of the present invention;

[0029] Figure 2 Schematic diagram of the trajectory of a single bionic structure groove in the fuel injection hole provided for Embodiment 1 of the present invention.

[0030] Figure 3 Schematic diagram of the multi-wave combustion chamber provided for Embodiment 2 of the present invention;

[0031] Figure 4 Schematic diagram of the semi-elliptical circumferential groove provided for Embodiment 2 of the present invention;

[0032] Wherein, 1 - bionic structure groove; 2 - groove one; 3 - groove two; 4 - groove three. DETAILED DESCRIPTION OF THE INVENTION

[0033] The present invention will be further described below in conjunction with the drawings and embodiments.

[0034] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0035] Without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other.

[0036] Embodiment 1:

[0037] In view of the problems of "short combustion cycle time, more insufficient in-cylinder combustion, serious energy consumption and pollution problems" existing in large-bore high-speed diesel engines mentioned in the background art, how to optimize the combustion system and construct a more efficient combustion process has become the key to improving the performance of large-bore high-speed diesel engines. A large number of research results show that the injection hole angle and quantity, injector structure, and combustion chamber shape are of great significance for optimizing the combustion system.

[0038] In order to achieve the purpose of optimizing the combustion system, this embodiment proposes an optimized injector. The injector includes a plurality of injection holes. The injection holes adopt a large-diameter type (here, the large diameter is a relative concept, and the diameter of the injection hole should be greater than a certain set threshold). The number of injection holes is appropriately selected, and each injection hole is non-uniformly distributed circumferentially along the axis of the injector, and the injection hole angles are also different. Four bionic structure grooves are uniformly engraved inside the injection hole. By imitating the flight trajectory of a bee hovering upward, the bionic structure grooves inside the injection hole are designed so that the fuel spray ejected by the injector is in a conical spiral shape.

[0039] Specifically, as Figure 1 and Figure 2 shown, the following is provided for illustration:

[0040] In this implementation manner, the diameter of the injection hole is D, and the value range of D is 0.4 mm to 1.0 mm. Preferably, the diameter D of the injection hole here is 0.8 mm; the number of injection holes is Z1, and the value range of Z1 is 4 to 8. Preferably, the number of injection holes Z1 here is taken as 4.

[0041] In this implementation manner, each injection hole is non-uniformly distributed circumferentially along the axis of the injector, and the angles of each injection hole are different. When the number of injection holes is 4, the angles of each injection hole are 75°, 90°, 120°, and 135° respectively.

[0042] In this implementation manner, the radius R of the injection hole is 0.4 mm, the length L of the fuel injection pipe bundle is 30 mm, and the width B of the bionic structure groove 1 is 0.01 mm, and the depth H is 0.01 mm. The four bionic structure grooves 1 are spaced 90° apart and are uniformly engraved on the inner wall of the injection hole. The bionic structure groove 1 is in the shape of a non-uniform pitch cylindrical helix, and its mathematical equation is:

[0043] x = 0.4cos2πt (1);

[0044] y = 0.4sin2πt (2);

[0045] z = 0.72t1.5 (3);

[0046] Wherein, t ∈ [0, 12], the units of x, y and z are mm, the pitch of any point on the spiral is P, and P = 1.2e 36.8z cos(4z), the unit is mm, and at this time the unit of z is radian, and the value is calculated by formula (3).

[0047] Embodiment 2:

[0048] This embodiment provides a combustion system for a large-bore high-speed diesel engine, which includes a combustion chamber and the injector described in Embodiment 1 of the present invention. The injector includes a plurality of injection holes. The inner cavity body of the combustion chamber is in a ω shape. Three semi-elliptical circumferential grooves are provided on the inner wall of each pit of the ω-shaped combustion chamber, and a multi-wave combustion chamber is formed through the three semi-elliptical circumferential grooves to adapt to the conical spiral fuel spray of the injector.

[0049] Specifically, as Figure 3 and Figure 4 shown, the following illustration is provided:

[0050] The circumferential grooves at the bottom of the wave-shaped combustion chamber (i.e., groove 2 of the first groove, groove 3 of the second groove, and groove 4 of the third groove) are semi-elliptical, and their major axes are on the same horizontal line. The angle α between the major axis and the horizontal line is 30° (the horizontal line refers to the line parallel to the horizontal plane when the combustion chamber is placed horizontally). Taking the major axis of groove 2 of the first groove as the x-axis and the minor axis of groove 2 of the first groove as the y-axis, the Figure 3 shown rectangular coordinate system is obtained.

[0051] In this implementation manner, preferably, the major axis a1 of groove 2 of the first groove is 30 mm, and the minor axis b1 of groove 2 of the first groove is 10 mm; the major axis a2 of groove 3 of the second groove is 50 mm, and the minor axis b2 of groove 3 of the second groove is 16 mm; the major axis a3 of groove 4 of the third groove is 70 mm, and the minor axis b3 of groove 4 of the third groove is 30 mm. Thus, the mathematical equations of the three semi-elliptical circumferential grooves at the bottom of the multi-wave combustion chamber can be given:

[0052] The equation of the semi-elliptical shape of groove 2 of the first groove is:

[0053]

[0054] The equation of the semi-elliptical shape of groove 3 of the second groove is:

[0055]

[0056] The equation of the semi-elliptical shape of groove 4 of the third groove is:

[0057]

[0058] The specific working principle of the combustion system of the large-bore high-speed diesel engine of the present invention is as follows:

[0059] Based on the design of the combustion system of the large-bore high-speed diesel engine, while retaining its original reasonable structural design (such as the original air filter, intercooler, supercharger, intake manifold, intake manifold, and air passage, etc., which are not the innovative points of the present invention, so they are not specifically illustrated here and the existing solutions can be adopted), the present invention mainly improves the fuel injection holes of the fuel injector and the combustion chamber structure. First, four spiral grooves are drilled inside the fuel injection holes to make the fuel spray ejected by the fuel injector generate regular rotational motion in the combustion chamber; secondly, three circumferential grooves are opened at the bottom of the multi-wave combustion chamber to adapt to the spiral fuel beam, and the incoming fuel and air can form a vortex together in the combustion chamber, making it easier to form a uniform mixture in the combustion chamber, improving the formation speed and quality of the combustible mixed gas, accelerating the combustion process, improving the thermal efficiency, reducing the cost, and improving the economic benefits.

[0060] Embodiment 3:

[0061] This embodiment provides a large-bore high-speed diesel engine, including the fuel injector described in Embodiment 1 of the present invention; or, including the combustion system of the large-bore high-speed diesel engine described in Embodiment 2 of the present invention.

[0062] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An injector, It is characterized in that It includes: An injector body, on the inner wall of the injection holes of the injector body, there are provided a plurality of bionic structure grooves, so that the oil spray ejected from the injection holes is in a conical spiral shape; The number range of the injection holes is four to eight, and the diameter of the injection holes is greater than a set threshold value; The bionic structure groove is in the shape of a non-uniform pitch cylindrical helix, where \(x = 0.4\cos(2\pi t)\), \(y = 0.4\sin(2\pi t)\), and \(z = 0.72t\). 1.5 , where \(t\) is a dimensionless number and \(t\in[0,12]\). The pitch of any point on the non-uniform pitch cylindrical helix groove is \(P\), and \(P = 1.2e\). 36.8z \(\cos(4z)\), with the unit of mm.

2. The injector according to claim 1, characterized in that Each bionic structure groove is arranged equidistantly and uniformly along the circumference of the injection hole.

3. The injector according to claim 1, characterized in that The number of bionic structure grooves is four, and the adjacent bionic structure grooves are spaced 90°.

4. A combustion system of a large-bore high-speed diesel engine, characterized in that It includes a combustion chamber and the injector according to any one of claims 1-3, and the injector includes a plurality of injection holes; The inner cavity body of the combustion chamber is in a ω shape, and on the inner wall of each pit of the ω-shaped combustion chamber, there are provided three semi-elliptical circumferential grooves.

5. The combustion system of a large-bore high-speed diesel engine according to claim 4, characterized in that The major axes of the three semi-elliptical circumferential grooves in the same pit are collinear, and the collinear straight line forms a set angle with the horizontal line.

6. The combustion system of a large-bore high-speed diesel engine according to claim 4 or 5, characterized in that The three semi-elliptical circumferential grooves are respectively groove one, groove two and groove three, and the major axis lengths of groove one, groove two and groove three are different. Taking the major axis of groove one as the x-axis and the minor axis of groove one as the y-axis to construct a rectangular coordinate system; The equation of the semi-ellipse of the first bevel is: y ≤ 0, -30 mm ≤ x ≤ 30 mm; The equation of the semi-ellipse of the second groove is: y ≤ 0, 30 mm ≤ x ≤ 130 mm; The equation of the semi-ellipse of Groove 3 is: y ≤ 0, 130 mm ≤ x ≤ 270 mm.

7. A large-bore high-speed diesel engine, characterized in that, It includes the injector according to any one of claims 1-3; or, it includes the combustion system of a large-bore high-speed diesel engine according to any one of claims 4-6.

Images