Piston for diesel engine

Abstract

The piston for the diesel engine comprises a piston body, the piston body is installed in an air cylinder in a sliding mode, the piston body is composed of a piston head part, a piston skirt part and a piston pin seat, and an air inlet valve avoiding pit and an exhaust valve avoiding pit are formed in the periphery of the top of the piston head part. A combustion chamber pit is formed in the middle of the top of the piston head, a flow dividing arc is arranged on the top of the side of the combustion chamber pit, and the combustion chamber pit is composed of an arc ridge, an inner chamber and an outer chamber. According to the oil-gas mixing device, oil-gas mixing quality optimization under the conditions of different loads and excess air coefficients is achieved through the unique arc ridges and the side entrainment structure, and when the loads are reduced or the excess air coefficients are increased, the arc ridges promote oil-gas mixing; and when the load is increased or the excess air coefficient is reduced, the mixing quality is further improved by side rolling flow, and the flexible adaptive design fundamentally solves the problems of the existing diesel engine in the aspects of fuel consumption rate and soot emission.

Description

Technical Field

[0001] The utility model belongs to the technical field of diesel engines. Specifically, the utility model relates to a piston for a diesel engine. Background Art

[0002] The engine piston is one of the most important and complex components in the engine. The engine fuel burns in the piston combustion chamber, and the piston combustion chamber and the upper surface are directly affected by the high-temperature and high-pressure gas. In various mechanical products, the exploration of engine thermal efficiency improvement technology is the most common thing.

[0003] The trend in the selection of combustion chamber forms for modern high-speed diesel engines is to pay more and more attention to energy conservation and environmental protection. The importance attached by users to engine fuel consumption and the continuous upgrading of national engine emission regulations have promoted the continuous optimization of piston design for engines.

[0004] In the prior art, it is difficult to improve the engine thermal efficiency, especially for diesel engines, which have incomplete combustion, low thermal efficiency, high fuel consumption rate, and high soot emissions. Summary of the Utility Model

[0005] The utility model provides a piston for a diesel engine, which solves the problems raised in the above background art.

[0006] In order to achieve the above object, the technical solution adopted by the utility model is as follows: A piston for a diesel engine includes a piston body. The piston body is slidably installed in a cylinder. The piston body is composed of a piston head, a piston skirt, and a piston pin boss. An intake valve relief pit and an exhaust valve relief pit are provided on the outer periphery of the top of the piston head. A combustion chamber pit is provided at the middle position of the top of the piston head. A diversion arc is provided at the top side of the combustion chamber pit. The combustion chamber pit is composed of an arc ridge, an inner chamber, and an outer chamber.

[0007] Preferably, annular grooves, a first annular groove, and a second annular groove are formed on the outer side wall of the piston head from top to bottom. A lower inner annular cooling groove is formed on the top end surface of the piston head. An upper inner annular cooling groove is formed on the bottom end surface of the piston head.

[0008] Preferably, the lower inner annular cooling groove and the upper inner annular cooling groove form an inner annular cooling groove up and down. An oil through hole is formed at the bottom of the piston head. One end of the oil through hole communicates with the lower inner annular cooling groove, and the other end communicates with the inner cavity of the piston skirt.

[0009] Preferably, the radius of the diversion arc is set to R1 = 9 mm, and the radius of the tip of the diversion arc is set to R2 = 1.5 mm.

[0010] Preferably, the arc ridge fillet is set to R3 = 3 mm, the inner chamber is set to a fillet R4 = 8 mm, and the outer chamber is set to a fillet R5 = 2 mm.

[0011] The beneficial effects of adopting the above technical solutions are as follows:

[0012] First, the composite swirl combustion chamber design in this utility model realizes the optimization of the fuel-air mixing quality under different load and excess air coefficient conditions through its unique arc ridge and side swirl structures. When the load decreases or the excess air coefficient increases, the arc ridge promotes fuel-air mixing; when the load increases or the excess air coefficient decreases, the side swirl further improves the mixing quality. This flexible adaptive design fundamentally solves the problems of fuel consumption rate and soot emission in existing diesel engines. Description of the Drawings

[0013] Figure 1 is the assembly drawing provided by this utility model;

[0014] Figure 2 is the assembly drawing provided by this utility model from another perspective;

[0015] Figure 3 is the structural view of the side swirl shape of this utility model;

[0016] Figure 4 is the bottom view provided by this utility model;

[0017] Figure 5 is the front view provided by this utility model;

[0018] Figure 6 is the structural view of the double swirl shape of this utility model;

[0019] Figure 7 is the comparison data of fuel consumption rate;

[0020] Figure 8 is the comparison data of soot emissions;

[0021] Among them:

[0022] 1. Piston head; 11. Intake valve relief pit; 12. Exhaust valve relief pit; 13. Combustion chamber pit; 14. Diverging arc; 15. Annular groove; 16. First annular groove; 17. Second annular groove; 18. Inner annular cooling groove; 19. Oil passage hole; 2. Piston skirt; 3. Piston pin boss. Detailed Implementation Modes

[0023] The following is a more detailed description of the specific implementation manner of the present utility model with reference to the accompanying drawings through the description of the embodiments, aiming to help those skilled in the art have a more complete, accurate and in-depth understanding of the concept and technical solution of the present utility model and facilitate its implementation.

[0024] Specifically, as Figures 1 to 8 shown, a piston for a diesel engine includes a piston body, the piston body is slidably installed in a cylinder, the piston body is composed of a piston head 1, a piston skirt 2 and a piston pin boss 3, an intake valve relief pit 11 and an exhaust valve relief pit 12 are provided on the outer periphery of the top of the piston head 1, a combustion chamber recess 13 is provided at the middle position of the top of the piston head 1, a diversion arc 14 is provided at the top side of the combustion chamber recess 13, and the combustion chamber recess 13 is composed of an arc ridge, an inner chamber and an outer chamber.

[0025] It should be noted that as the load of the diesel engine decreases or the excess air coefficient increases, the penetration ability of the fuel jet weakens, and the arc ridge of the compound swirl combustion chamber effectively improves the fuel-air mixing quality; as the load of the diesel engine increases or the excess air coefficient decreases, the penetration ability of the fuel jet increases, and the diversion shape of the side swirl combustion chamber more significantly improves the fuel-air mixing quality.

[0026] There are two optimizations in this embodiment:

[0027] 1. Optimization when the load decreases or the excess air coefficient increases

[0028] When the load of the diesel engine decreases or the excess air coefficient increases, the penetration ability of the fuel jet is relatively weakened, which may lead to insufficient fuel-air mixing and affect the combustion efficiency. At this time, the arc ridge design in the compound swirl combustion chamber plays a key role. The arc ridge can not only effectively guide the intake air to form a vortex, but also promote the diffusion of the fuel mist during fuel injection, making the fuel more widely distributed in the combustion chamber. This design increases the contact area between the fuel and the air, enhances the uniformity and quality of the fuel-air mixing, thereby improving the combustion process and reducing the fuel consumption rate. At the same time, due to more sufficient fuel-air mixing and more complete combustion, the generation of unburned hydrocarbons and particulate matter is reduced, which is beneficial to reducing the emission of soot;

[0029] 2. Optimization when the load increases or the excess air coefficient decreases

[0030] On the contrary, when the load of the diesel engine increases or the excess air coefficient decreases, the penetration ability of the fuel jet increases, and it is easy to form a local rich mixture zone, which is also not conducive to the improvement of combustion efficiency and emission performance. To address this issue, the side swirl design in the compound swirl combustion chamber demonstrates its unique advantages. The side swirl combustion chamber, through its specific flow splitting shape, guides part of the fuel to flow along the side wall during fuel injection, forming a side swirl. This not only effectively alleviates the problem of excessive fuel concentration in the central region but also promotes the mixing of fuel and air in a wider area. This improvement in the mixing method enables better fuel-air mixing quality even under high load or low excess air coefficient conditions, further enhancing combustion efficiency and reducing emissions.

[0031] An annular groove 15, a first annular groove 16, and a second annular groove 17 are formed on the outer side wall of the piston head 1 from top to bottom. An inner lower annular cooling groove is formed on the top end face of the piston head 1, and an inner upper annular cooling groove is formed on the bottom end face of the piston head 1.

[0032] The inner lower annular cooling groove and the inner upper annular cooling groove form an inner annular cooling groove 18 up and down. An oil passage hole 19 is formed at the bottom of the piston head 1. One end of the oil passage hole 19 communicates with the inner lower annular cooling groove 18, and the other end communicates with the inner cavity of the piston skirt 2.

[0033] The radius of the flow splitting arc 14 is set to R1 = 9 mm, and the tip radius of the flow splitting arc 14 is set to R2 = 1.5 mm.

[0034] The arc ridge fillet is set to R3 = 3 mm, the inner chamber is set to a fillet R4 = 8 mm, and the outer chamber is set to a fillet R5 = 2 mm;

[0035] It should be noted that through appendix Figure 7 It is obtained that at the working conditions of 1800 r / min - 1990 Nm and 1200 r / min - 2400 Nm respectively, the fuel consumption rate HPISFC is the lowest, that is, the combustion chamber KS8 scheme;

[0036] It should be noted that through appendix Figure 8 It is obtained that at the working conditions of 1800 r / min - 1990 Nm and 1200 r / min - 2400 Nm respectively, the soot emission is the lowest, that is, the combustion chamber KS8 scheme.

[0037] In this embodiment, the product solves the problems of fuel consumption rate and soot emission of the existing diesel engine by using the KS8 scheme.

[0038] The following uses specific embodiments to elaborate on the specific working methods: Embodiment 1

[0039] Diffusion combustion dominates the combustion process of direct injection diesel engines. Good fuel-air mixing quality is the key to improving the diffusion combustion process of direct injection diesel engines. With the continuous increase in the injection pressure of the high-pressure fuel supply system, the breakup and atomization quality of the fuel jet in the cylinder have been improved. However, the high injection pressure also leads to an increase in the penetration distance of the fuel spray, and spray wall impingement has become an inevitable phenomenon in medium and small bore diesel engines. The wall-guided combustion system utilizes a specially designed combustion chamber wall structure to guide the fuel jet to move in the cylinder, making full use of the kinetic energy of the high-speed fuel jet, promoting the macroscopic mixing of fuel and air, and improving the fuel-air mixing quality. Embodiment 2

[0040] On the basis of the traditional ω combustion chamber, the double swirl combustion chamber is provided with arc ridges. After the fuel jet impinges on the arc ridges, swirl flows are formed in the inner chamber and the outer chamber in a certain proportion. The side swirl combustion chamber is provided with a flow splitting profile on the side wall of the traditional ω combustion chamber. After the fuel jet impinges on the tip of the flow splitting profile, a wall jet that laterally swirls is formed along the split arc, and when the wall jets of adjacent fuel beams flow out of the split arc, an interference effect occurs, forming an interference wall jet that moves towards the center of the combustion chamber. Embodiment 3

[0041] The design concept of the composite swirl combustion system is to combine the wall guiding advantages of the double swirl and side swirl combustion chambers, and at the same time promote the diffusion of fuel in the axial and circumferential directions of the combustion chamber. The fuel jet forms axial and circumferential swirl flows in sequence in the composite swirl combustion chamber: the fuel jet first impinges on the arc ridges, forming swirl flows in the inner chamber and the outer chamber; subsequently, the fuel in the outer chamber impinges on the tip of the flow splitting profile, forming a laterally swirling wall jet and an interference wall jet.

[0042] The above has made an exemplary description of the present invention in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited by the above methods. As long as various non-substantive improvements are made by adopting the method concept and technical solution of the present invention; or without improvement, the above concept and technical solution of the present invention are directly applied to other occasions, all are within the protection scope of the present invention.

Claims

1. A piston for a diesel engine, comprising a piston body which is slidably mounted in a cylinder. The piston body consists of a piston head (1), a piston skirt (2) and a piston pin boss (3), characterized in that, An intake valve relief pit (11) and an exhaust valve relief pit (12) are provided on the outer periphery of the top of the piston head (1). A combustion chamber pit (13) is provided at the middle position of the top of the piston head (1). A diversion arc (14) is provided at the top side of the combustion chamber pit (13). The combustion chamber pit (13) is composed of an arc ridge, an inner chamber and an outer chamber; An annular groove (15), a first annular groove (16) and a second annular groove (17) are formed on the outer side wall of the piston head (1) from top to bottom. A lower inner annular cooling groove is formed on the top end surface of the piston head (1). An upper inner annular cooling groove is formed on the bottom end surface of the piston head (1); The lower inner annular cooling groove and the upper inner annular cooling groove form an inner annular cooling groove (18) up and down. An oil through hole (19) is formed at the bottom of the piston head (1). One end of the oil through hole (19) communicates with the lower inner annular cooling groove (18), and the other end communicates with the inner cavity of the piston skirt (2).

2. A piston for a diesel engine according to claim 1, characterized in that: The radius of the diversion arc (14) is set to R1 = 9 mm, and the tip radius of the diversion arc (14) is set to R2 = 1.5 mm.

3. A piston for a diesel engine according to claim 1, characterized in that: The arc ridge fillet is set to R3 = 3 mm, the inner chamber is set to a fillet R4 = 8 mm, and the outer chamber is set to a fillet R5 = 2 mm.

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