阅读说明：本技术 点燃压燃汽油机用活塞 (Piston for igniting compression ignition gasoline engine ) 是由 王文建 桂强 蔡文新 史来锋 王静秋 于 2020-12-01 设计创作，主要内容包括：本发明涉及点燃压燃汽油机用活塞,包括活塞本体,其特征是活塞本体的顶面中心设置有凹坑、第一和第二进气避让坑、第一和第二排气避让坑,凹坑包括侧壁和坑底,坑底对准喷油器油束喷射方向,第一和第二进气避让坑、第一和第二排气避让坑沿凹坑的周向依次布置,第一进气避让坑与第二进气避让坑之间和第一排气避让坑与第二排气避让坑之间分别形成第一顶面,第一进气避让坑与第二排气避让坑之间和第一排气避让坑与第二进气避让坑之间分别形成第二顶面,第二顶面的水平高度不低于第一顶面的水平高度。采用本发明,凹坑内形成浓混合气且易于点燃产生火核,进而,火核被快速引导至凹坑外区域使稀薄混合气压燃,有效地提高了发动机的热效率。(The invention relates to a piston for igniting and compression-igniting gasoline engines, which comprises a piston body and is characterized in that a pit, a first air inlet avoiding pit, a second air inlet avoiding pit, a first exhaust avoiding pit and a second exhaust avoiding pit are arranged in the center of the top surface of the piston body, the pit comprises a side wall and a pit bottom, the pit bottom is aligned to the oil beam injection direction of an oil injector, the first air inlet avoiding pit, the second air inlet avoiding pit, the first exhaust avoiding pit and the second exhaust avoiding pit are sequentially arranged along the circumferential direction of the pit, a first top surface is respectively formed between the first air inlet avoiding pit and the second air inlet avoiding pit and between the first exhaust avoiding pit and the second exhaust avoiding pit, a second top surface is respectively formed between the first air inlet avoiding pit and the second exhaust avoiding pit and between the first exhaust avoiding pit and the second air inlet avoiding pit, and the horizontal height of the second top surface is not lower. By adopting the invention, the pit is internally provided with the rich mixed gas which is easy to ignite to generate the fire core, and then the fire core is quickly guided to the area outside the pit to compress the lean mixed gas, thereby effectively improving the thermal efficiency of the engine.)

1. A piston for igniting compression ignition gasoline engine comprises a piston body (1), and is characterized in that: the top surface of the piston body (1) is provided with a pit (2), a first air inlet avoidance pit (3.1), a second air inlet avoidance pit (3.2), a first exhaust avoidance pit (4.1) and a second exhaust avoidance pit (4.2), the pit (2) is located in the center of the top surface of the piston body (1), the pit (2) comprises a side wall (2.1) and a pit bottom (2.2), the pit bottom (2.2) is aligned with the oil jet spraying direction of an oil sprayer, the first air inlet avoidance pit (3.1), the second air inlet avoidance pit (3.2), the first exhaust avoidance pit (4.1) and the second exhaust avoidance pit (4.2) are sequentially arranged along the circumferential direction of the pit (2), a first top surface (5) is formed between the first air inlet avoidance pit (3.1) and the second air inlet avoidance pit (3.2) and between the first exhaust avoidance pit (4.1) and the second exhaust avoidance pit (4.2), and a first exhaust avoidance pit (4.1) and a second exhaust avoidance pit (4.2) are formed between the first air inlet avoidance pit (3.1) and the second exhaust avoidance pit (4.2), and a first exhaust avoidance pit (4.2) are formed between the second exhaust avoidance pit (3.1) respectively The level of the top surface (6) and the level of the second top surface (6) are not lower than the level of the first top surface (5).

2. The piston for an ignition compression ignition gasoline engine as set forth in claim 1, wherein: the side wall (2.1) is in an inverted round table shape, and the pit bottom (2.2) is in a spherical surface shape.

3. A piston for an ignition compression ignition gasoline engine as claimed in claim 1 or 2, wherein: the first top surface (5) comprises a first flow guide surface (5.1) and a first transition cambered surface (5.2), the first flow guide surface (5.1) is arranged from outside to inside, the first transition cambered surface (5.2) is connected with the pit (2), and the first flow guide surface (5.1) is inclined inwards and upwards and has an included angle larger than 1 degree with the horizontal plane.

4. A piston for an ignition compression ignition gasoline engine as claimed in claim 1 or 2, wherein: the second top surface (6) comprises a second flow guide surface (6.1), a flow guide groove (6.3) and a second transition arc surface (6.2) which are arranged from outside to inside, the second flow guide surface (6.1) is connected with the pit (2) through the flow guide groove (6.3) and the second transition arc surface (6.2), the horizontal height of the flow guide groove (6.3) is not lower than that of the first top surface (5), and the second flow guide surface (6.1) is inwards inclined upwards and has an included angle larger than 1 degree with the horizontal plane.

5. A piston for an ignition compression ignition gasoline engine as claimed in claim 3, wherein: the second top surface (6) comprises a second flow guide surface (6.1), a flow guide groove (6.3) and a second transition arc surface (6.2) which are arranged from outside to inside, the second flow guide surface (6.1) is connected with the pit (2) through the flow guide groove (6.3) and the second transition arc surface (6.2), the horizontal height of the flow guide groove (6.3) is not lower than that of the first top surface (5), and the second flow guide surface (6.1) is inwards inclined upwards and has an included angle larger than 1 degree with the horizontal plane.

6. A piston for an ignition compression ignition gasoline engine as claimed in claim 1 or 2, wherein: the diameter of the upper edge of the pit bottom (2.2) is 16-19% of the diameter of the piston body (1).

7. A piston for an ignition compression ignition gasoline engine as claimed in claim 3, wherein: the diameter of the upper edge of the pit bottom (2.2) is 16-19% of the diameter of the piston body (1).

8. The piston for an ignition compression ignition gasoline engine as set forth in claim 4, wherein: the diameter of the upper edge of the pit bottom (2.2) is 16-19% of the diameter of the piston body (1).

9. The piston for an ignition compression ignition gasoline engine as set forth in claim 5, wherein: the diameter of the upper edge of the pit bottom (2.2) is 16-19% of the diameter of the piston body (1).

10. The piston for an ignition compression ignition gasoline engine as set forth in claim 2, wherein: the conicity of the side wall (2.1) is 12-20 degrees.

Technical Field

The invention relates to ultra-lean combustion for igniting compression ignition, in particular to a piston for igniting compression ignition gasoline engine.

Background

Based on the requirements of energy conservation and emission reduction, the gasoline engine further improves the heat efficiency of the gasoline engine through a compression ignition technology, namely, a spark plug is used for igniting a part of working media to form a fire core to heat the rest of the working media, and pressure required by compression ignition is formed in a cylinder, so that the rest of the working media are compressed and ignited, and the high compression ratio and the ultra-lean combustion of the gasoline are realized.

CN101338693A discloses a device and a method for expanding the load range of compression ignition type gasoline, wherein a central pit is arranged at the center of the top surface of a piston, oil is injected twice in a cylinder, oil is injected for the first time in an intake stroke to form a thin working medium in the cylinder, oil is injected for the second time when the piston moves to the vicinity of an upper dead point in a compression stroke, gasoline is injected into the central pit, a spark plug is used for igniting a high-concentration working medium in the central pit to form a fire core, the thin working medium at the periphery is heated through the fire core, and finally compression ignition of the thin working medium at the periphery is realized. In order to better heat the thin working medium at the periphery by the fire core, a larger central pit is needed, which is not beneficial to the concentration of secondary injection gasoline and the energy concentration of a spark plug, and limits the improvement of the thermal efficiency of the engine.

CN103195603A discloses a diesel engine with swirl chamber, the combustion chamber is divided into two parts, swirl chamber distributed in the cylinder head and main combustion chamber composed of cylinder/cylinder head and piston, both are connected by channel. The split combustion chamber structure occupies a large space, and cannot be arranged in a compact gasoline engine. The invention integrates an ignition area (a central pit), a flame injection structure (a slit between a pit wall and a cylinder cover), a fast combustion area (a circumferential diversion trench at the periphery of the pit), a compression ignition area (other areas) and the like on the top surface of the piston, and has compact structure.

CN207420706U discloses a piston top surface combustion chamber structure and engine, and basic structure is that the convex top piston top surface has arranged central big pit and four valve and dodges the pit, is provided with extra guiding gutter between central big pit and two valve dodge pits wherein. The structure adopting the central large pit has the advantages that the compression ratio is severely limited, the requirement of igniting and compressing gasoline cannot be met, and the efficient combustion heat efficiency performance of igniting and compressing gasoline cannot be further realized.

In order to overcome the defects in the prior art, the invention provides a piston for igniting compression ignition gasoline engine. The invention can realize the full mixing of gasoline and air, and the generated fire core has high temperature and high transmission speed, thereby effectively improving the heat efficiency of the engine.

Disclosure of Invention

The invention aims to provide a piston for igniting and compression-igniting gasoline engine, which can effectively improve the thermal efficiency of the engine.

In order to achieve the purpose, the invention adopts the following technical scheme: a piston for igniting and compression-igniting gasoline engine comprises a piston body, and is characterized in that a pit, a first air inlet avoiding pit and a second air inlet avoiding pit are arranged on the top surface of the piston body, the first exhaust avoiding pit and the second exhaust avoiding pit are located in the center of the top surface of the piston body, the pits comprise side walls and pit bottoms, the pit bottoms are aligned to the oil beam spraying direction of the oil sprayer, the first intake avoiding pit, the second intake avoiding pit, the first exhaust avoiding pit and the second exhaust avoiding pit are sequentially arranged along the circumferential direction of the pits, a first top surface is respectively formed between the first intake avoiding pit and the second intake avoiding pit and between the first exhaust avoiding pit and the second exhaust avoiding pit, a second top surface is respectively formed between the first intake avoiding pit and the second exhaust avoiding pit and between the first exhaust avoiding pit and the second intake avoiding pit, and the horizontal height of the second top surface is not lower than that of the first top surface.

Furthermore, the side wall is in an inverted round table shape, and the pit bottom is in a spherical surface shape.

Further, the first top surface comprises a first flow guide surface and a first transition arc surface which are arranged from outside to inside, the first flow guide surface is connected with the pit through the first transition arc surface, and the first flow guide surface inclines inwards and upwards and forms an included angle larger than 1 degree with the horizontal plane.

Further, the second top surface comprises a second guide surface, a guide groove and a second transition arc surface which are arranged from outside to inside, the second guide surface is connected with the pit through the guide groove and the second transition arc surface, the horizontal height of the guide groove is not lower than that of the first top surface, and the second guide surface inclines inwards and upwards and forms an included angle larger than 1 degree with the horizontal plane.

Further, the diameter of the pit bottom edge is 16% -19% of the diameter of the piston body.

Further, the taper of the side wall is 12-20 degrees.

The working process of the invention comprises the following steps:

1. intake stroke

The inlet valve is opened, the piston moves from the upper dead point to the lower dead point, the oil nozzle injects oil for the first time, and thin atomized gasoline is formed in the cylinder;

2. compression stroke

The air inlet valve is closed, the piston moves from the bottom dead center to the top dead center, and meanwhile, a flow guide surface and a flow guide groove at the top of the piston form tumble flow and vortex in the cylinder in the process that the piston moves towards the top dead center, so that the thin atomized gasoline is fully mixed with air; when the piston moves to the vicinity of the top dead center, the oil nozzle sprays gasoline into the pit to form a high-concentration oil-gas mixture in the pit, and the high-concentration oil-gas mixture in the pit is ignited by using the spark plug to form a fire core; the heat of the fire core is rapidly transferred to the periphery of the pit along the diversion trench to heat the thin working medium, the thin working medium around the pit is subjected to compression ignition under the combined action of the pressure applied by the piston and the heat of the fire core, and layered combustion and ultra-thin combustion are realized;

3. power stroke

Under the action of impact force generated by violent combustion of working media, the piston moves from the top dead center to the bottom dead center and drives the crankshaft to rotate;

4. exhaust stroke

Under the action of inertia, the piston moves from the bottom dead center to the top dead center, and the exhaust valve is opened to exhaust the gas in the cylinder.

The invention is provided with the guide groove and the guide surface, and forms vortex and tumble in the cylinder during compression, thereby leading the gasoline sprayed for the first time to be fully mixed with air in the cylinder.

The invention prevents the interference between the top surface of the piston and the air valve by arranging the air valve avoiding pit.

The pit is arranged in the center of the top of the piston, the bottom of the pit is aligned to the oil jet injection direction of the oil injector, and the guide grooves which are beneficial to forming vortex are arranged around the pit, so that gasoline which is injected for the second time is fully mixed with air in the pit, lean mixed gas is formed in the area outside the pit, rich mixed gas is formed in the area inside the pit, the rich mixed gas in the area inside the pit is easy to ignite to generate a fire core, and the temperature and the pressure of the lean mixed gas in the area outside the pit are rapidly improved to be compression-ignited through slit injection and circumferential vortex guidance, so that the thermal efficiency of an engine is effectively improved.

The taper of the side wall is set to be 12-20 degrees, namely the side wall is approximately vertical to the upper edge plane of the pit bottom, so that the energy concentration of secondary injection gasoline and a spark plug is facilitated, the temperature of a formed flame kernel is higher, and the heat efficiency of the engine is further improved.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a top view of FIG. 1;

FIG. 3 is a cross-sectional view of FIG. 1;

FIG. 4 is a schematic diagram of a pit structure of the present invention;

FIG. 5 is a top view of FIG. 4;

FIG. 6 is a schematic diagram of the relationship between the spray direction of the oil jet and the pits of the present invention.

In the figure: 1-a piston body; 2-pits; 2.1-side wall; 2.2-pit bottom; 3.1-first air intake avoiding pit; 3.2-second air inlet avoiding pit; 4.1-first exhaust avoiding pit; 4.2-second exhaust avoiding pit; 5-a first top surface; 5.1-a first flow guide surface; 5.2-first transition camber; 6-a second top surface; 6.1-a second flow guide surface; 6.2-second transition arc; 6.3-diversion trench.

Detailed Description

The present invention is further described with reference to the following drawings and examples, but the examples should not be construed as limiting the present invention.

A piston for igniting and compressing gasoline engine comprises a piston body 1, a concave pit 2, a first air inlet avoiding pit 3.1, a second air inlet avoiding pit 3.2, a first exhaust avoiding pit 4.1 and a second exhaust avoiding pit 4.2 are arranged on the top surface of the piston body 1, the concave pit 2 is positioned in the center of the top surface of the piston body 1, the concave pit 2 comprises a side wall 2.1 and a pit bottom 2.2, the pit bottom 2.2 is aligned with the oil beam injection direction of a fuel injector, the first air inlet avoiding pit 3.1, the second air inlet avoiding pit 3.2, the first exhaust avoiding pit 4.1 and the second exhaust avoiding pit 4.2 are sequentially arranged along the circumferential direction of the concave pit 2, a first top surface 5 is respectively formed between the first air inlet avoiding pit 3.1 and the second air inlet avoiding pit 3.2 and between the first exhaust avoiding pit 4.1 and the second exhaust avoiding pit 4.2, and a second top surface 6 is respectively formed between the first exhaust avoiding pit 4.1 and the second exhaust avoiding pit 3.2, the level of the second top surface 6 is not lower than the level of the first top surface 5.

The preferred embodiments are: in the above scheme, the side wall 2.1 is in the shape of an inverted circular truncated cone, and the pit bottom 2.2 is in the shape of a spherical surface.

The preferred embodiments are: in the above scheme, the first top surface 5 includes a first flow guiding surface 5.1 and a first transition arc surface 5.2 arranged from outside to inside, the first flow guiding surface 5.1 is connected with the pit 2 through the first transition arc surface 5.2, and the first flow guiding surface 5.1 is inclined inwards and upwards and has an included angle greater than 1 ° with a horizontal plane.

The preferred embodiments are: in the above scheme, the second top surface 6 includes a second flow guiding surface 6.1, a flow guiding groove 6.3 and a second transition arc surface 6.2, the second flow guiding surface 6.1 is connected with the pit 2 through the flow guiding groove 6.3 and the second transition arc surface 6.2, the horizontal height of the flow guiding groove 6.1 is not lower than that of the first top surface 5, and the second flow guiding surface 6.2 is inclined upwards inwards and has an included angle greater than 1 ° with the horizontal plane.

The preferred embodiments are: in the scheme, the diameter of the upper edge of the pit bottom 2.2 is 16-19% of the diameter of the piston body 1.

The preferred embodiments are: in the solution according to claim 2, the taper of the side wall 2.1 is 12 ° to 20 °.

Details not described in the present specification are prior art known to those skilled in the art.