阅读说明：本技术 一种中重型点燃式发动机燃烧室 (Medium-heavy ignition engine combustion chamber ) 是由 王浒 赵旭敏 尧命发 郑尊清 刘海峰 于 2020-08-20 设计创作，主要内容包括：本发明公开了一种中重型点燃式发动机的燃烧室,包括由气缸盖的底面、活塞的顶面和气缸的壁面封闭组成的空间。气缸盖的底面为水平面,气缸盖的中心位置设置有火花塞安装孔。活塞顶面的中间为弧形凹部,在弧形凹部的左右两侧分别依次连接有喉部、半ω型凹部及外缘部,彼此之间光滑连接。本发明提高缸内湍流强度的同时改善气缸盖底部的气流运动,进而提高燃烧速率,降低缸盖底部温度,抑制爆震,降低缸盖底板开裂的风险。(The invention discloses a combustion chamber of a medium and heavy ignition engine, which comprises a space formed by closing the bottom surface of a cylinder cover, the top surface of a piston and the wall surface of a cylinder. The bottom surface of the cylinder cover is a horizontal plane, and a spark plug mounting hole is formed in the center of the cylinder cover. The middle of the top surface of the piston is an arc-shaped concave part, and the left side and the right side of the arc-shaped concave part are respectively and sequentially connected with a throat part, a semi-omega-shaped concave part and an outer edge part which are smoothly connected with each other. According to the invention, the turbulence intensity in the cylinder is improved, and the airflow movement at the bottom of the cylinder cover is improved, so that the combustion rate is improved, the temperature at the bottom of the cylinder cover is reduced, the detonation is inhibited, and the risk of cracking of the bottom plate of the cylinder cover is reduced.)

1. A combustion chamber of a medium-heavy ignition engine comprises a space formed by closing the bottom surface of a cylinder cover, the top surface of a piston and the wall surface of a cylinder, wherein a spark plug mounting hole is formed in the center of the cylinder cover, and the combustion chamber is characterized in that:

the bottom surface of the cylinder cover is a horizontal plane, the middle of the top surface of the piston is an arc-shaped concave part, the left side and the right side of the arc-shaped concave part are respectively and sequentially connected with a throat part, a semi-omega-shaped concave part and an outer edge part, the outer edge part is a horizontal plane, the arc-shaped concave part, the throat part, the semi-omega-shaped concave part and the outer edge part are smoothly connected with each other, the longitudinal central axis of the top surface of the piston is taken as a symmetry axis, the arc-shaped concave part, the semi-omega-shaped concave part and the outer edge part which are positioned on the left side and the right side of the longitudinal central axis of the top surface of the piston are arranged in a bilateral symmetry mode relative to the longitudinal central axis, and the arc-shaped.

2. The combustion chamber of a medium and heavy duty spark ignition engine of claim 1, characterized in that: the radius of the arc-shaped concave part is 40-50% of the diameter of the cylinder, and the distance between the farthest position of the arc-shaped concave part from the bottom surface of the cylinder cover and the plane of the bottom surface of the cylinder cover is 15-25% of the diameter of the cylinder.

3. The combustion chamber of a medium-heavy type spark ignition engine according to claim 1 or 2, characterized in that: the distance between the throat part of the piston and the bottom surface of the cylinder cover at the position closest to the bottom surface of the cylinder cover is 1-2% of the diameter of the cylinder.

4. The combustion chamber of a medium and heavy duty spark ignition engine of claim 3, characterized in that: the included angle between the tangent line of the connection part of the semi-omega-shaped concave part and the outer edge part and the bottom surface of the cylinder cover 1 is 60-120 degrees, the included angle between the tangent line of the connection part of the semi-omega-shaped concave part and the throat part and the bottom surface of the cylinder cover is 25-30 degrees, and the distance between the farthest position of the semi-omega-shaped concave part from the bottom surface of the cylinder cover and the horizontal plane of the outer edge part is 3-6 percent of the diameter of the cylinder.

5. The combustion chamber of a medium and heavy duty spark ignition engine of claim 4, characterized in that: the distance between the nearest position of the left throat part to the bottom surface of the cylinder cover and the nearest position of the right throat part to the bottom surface of the cylinder cover is 65-75% of the diameter of the cylinder.

6. The combustion chamber of a medium and heavy duty spark ignition engine of claim 5, characterized in that: the width of the outer edge part of the piston top surface is 3-5% of the cylinder diameter.

Technical Field

The invention relates to the technical field of engines, in particular to a combustion chamber of a medium-heavy ignition engine.

Background

At present, most medium-heavy ignition engines (including gasoline engines, natural gas engines, methanol engines and the like) are obtained by directly modifying diesel engines, cannot be fully adapted to premixed combustion modes, are weak in-cylinder tumble flow, low in turbulence intensity, slow in fuel flame propagation, easy to cause detonation, and limited in further improvement of heat efficiency. In order to solve the problems, Chinese patent CN209855911U discloses a combustion system for igniting an engine by using gasoline on the basis of a diesel engine, on the basis of keeping a flat-bottom cylinder cover of the original diesel engine, an oblique axis vortex is formed in a cylinder through the design of a spiral air inlet channel and a tangential air inlet channel, the guide of air flow motion is realized by matching with the top surface of an integrally concave arc piston, the longitudinal tumble strength and the holding capacity in the cylinder are effectively improved, and then the turbulence strength in the cylinder close to the upper dead point is increased through large-scale tumble crushing at the end of a compression stroke. However, the combustion system still has some problems, in the compression and combustion processes, due to the adoption of the flat-bottom cylinder cover, the area close to the bottom of the cylinder cover in the combustion chamber is difficult to form effective airflow movement, the speed is low, the combustion speed is slow, heat is easy to accumulate, hot spots are induced to generate spontaneous combustion, meanwhile, the risk of cracking of a bottom plate of the cylinder cover is increased, and the structure of the combustion chamber needs to be further optimally designed.

Disclosure of Invention

The invention aims to overcome the defects in the prior art, and provides a combustion chamber of a medium-heavy ignition engine, which improves the turbulence intensity in a cylinder and simultaneously improves the airflow movement at the bottom of a cylinder cover, thereby improving the combustion rate, reducing the temperature at the bottom of the cylinder cover, inhibiting detonation and reducing the risk of cracking of a bottom plate of the cylinder cover.

The purpose of the invention is realized by the following technical scheme.

A combustion chamber of a medium-heavy ignition engine comprises a space formed by closing the bottom surface of a cylinder cover, the top surface of a piston and the wall surface of a cylinder, wherein a spark plug mounting hole is formed in the center of the cylinder cover;

the bottom surface of the cylinder cover is a horizontal plane, the middle of the top surface of the piston is an arc-shaped concave part, the left side and the right side of the arc-shaped concave part are respectively and sequentially connected with a throat part, a semi-omega-shaped concave part and an outer edge part, the top wall of the outer edge part is a horizontal plane, the arc-shaped concave part, the throat part, the semi-omega-shaped concave part and the outer edge part are smoothly connected with each other, the longitudinal central axis of the top surface of the piston is taken as a symmetry axis, the arc-shaped concave part, the semi-omega-shaped concave part and the outer edge part which are positioned on the left side and the right side of the longitudinal central axis of the top surface of the piston are arranged in a bilateral symmetry mode around the longitudinal central axis, and the arc-.

Compared with the prior art, the technical scheme of the invention has the following beneficial effects:

the design of the cylindrical concave part is utilized to guide the tumble motion, the tumble intensity and the turbulent intensity in the cylinder at the moment of near ignition are enhanced, and the flame propagation at the initial stage is promoted; the design of the throat and the semi-omega-shaped concave part improves the flow extrusion strength, strengthens the airflow movement of the combustion chamber close to the bottom of the cylinder cover, reduces the temperature of the bottom of the cylinder cover, effectively inhibits detonation, and accelerates the combustion rate of the mixed gas in the peripheral area of the combustion chamber. Therefore, when tumble flow is formed in the cylinder of the engine with the flat-bottom cylinder cover, the combustion rate can be improved and knocking can be inhibited at the same time by adopting the invention, and the risk of cracking of the bottom plate of the cylinder cover is reduced.

Drawings

FIG. 1 is a schematic structural diagram of a combustion chamber of a medium and heavy ignition type engine according to the invention;

FIG. 2 is a top plan view of the piston taken in the direction B of the combustion chamber shown in FIG. 1;

FIG. 3 is a schematic view of the flow conditions of the compression stroke air stream;

fig. 4 is a schematic view of the airflow after the spark plug is fired.

Detailed Description

To further illustrate the functional structure of the present invention, the present invention is described in detail below with reference to the accompanying drawings and preferred embodiments, but it should be understood that the scope of the present invention is not limited by the specific embodiments.

As shown in fig. 1, the combustion chamber of a medium-heavy type spark ignition engine of the present invention includes a space enclosed by a bottom surface of a cylinder head 1, a top surface of a piston 2, and a wall surface of a cylinder 3, and a spark plug mounting hole 4 is provided at a central position of the cylinder head 1.

The bottom surface of the cylinder head 1 is a horizontal plane, the middle of the top surface of the piston 2 is an arc-shaped recess 201, the left side and the right side of the arc-shaped recess 201 are respectively and sequentially connected with a throat part 202, a semi-omega-shaped recess 203 and an outer edge part 204, the outer edge part 204 is a horizontal plane, and the arc-shaped recess 201, the throat part 202, the semi-omega-shaped recess 203 and the outer edge part 204 are smoothly connected with each other. As shown in fig. 2, the arc-shaped recess 201, the semi- ω -shaped recess 203, and the outer edge 204 located on both left and right sides of the longitudinal center axis of the piston top surface are provided symmetrically with respect to the longitudinal center axis, with the longitudinal center axis of the piston top surface being a symmetry axis. The arc-shaped recess 201, the semi-omega-shaped recess 203 and the outer edge 204 are respectively arranged on the top surface of the piston in a full length along a direction parallel to the longitudinal central axis of the top surface of the piston.

Preferably, the radius R of the arc-shaped concave part 201 is 40-50% of the cylinder diameter D, and the distance H1 between the farthest position of the arc-shaped concave part 201 from the bottom surface of the cylinder cover 1 and the plane where the bottom surface of the cylinder cover 1 is located is 15-25% of the cylinder diameter D.

Preferably, the distance H2 between the bottom surface of the cylinder head 1 and the nearest part of the throat 202 of the piston 2 from the bottom surface of the cylinder head 1 is 1-2% of the cylinder diameter D. Preferably, an included angle α between a tangent line of the half- ω -shaped recess 203 connected with the outer edge portion 204 and the bottom surface of the cylinder head 1 is 60 to 120 °, an included angle β between a tangent line of the half- ω -shaped recess 203 connected with the throat portion 202 and the bottom surface of the cylinder head 1 is 25 to 30 °, and a distance H3 between the farthest position of the half- ω -shaped recess 203 from the bottom surface of the cylinder head 1 and the horizontal plane where the outer edge portion 204 is located is 3 to 6% of the cylinder diameter D.

Preferably, the distance L1 between the closest of the left throat 202 to the bottom surface of the cylinder head 1 and the closest of the right throat 202 to the bottom surface of the cylinder head 1 is 65-75% of the cylinder diameter D.

Preferably, the width L2 of the outer edge portion 204 of the piston crown surface is 3-5% of the cylinder diameter D.

Fig. 3 is a schematic diagram of the flow of the mixture in the cylinder during the compression stroke of the piston 2. As shown in fig. 3, in the compression stroke, a regular clockwise longitudinal tumble motion is formed under the guidance of the arc-shaped recess 201. At the same time, due to the squeezing action of the piston 2, the air flow flows from the arc-shaped recess 201 and the outer rim portion 204 to the semi- ω -shaped recess 203, and a squeezing flow of a certain intensity is generated. Therefore, the air flow movement of the combustion chamber close to the bottom of the cylinder cover can be enhanced, the temperature of the bottom of the cylinder cover is reduced, and knocking is effectively inhibited.

FIG. 4 is a schematic view of the flow of the mixture in the combustion chamber during combustion. After spark ignition, the air-fuel mixture at the position of the arc-shaped recess 201 is ignited first, the in-cylinder temperature pressure rises sharply, a pressure difference between the position of the arc-shaped recess 201 and the throat 202 is formed, and the unburned air-fuel mixture at the position of the arc-shaped recess 201 is forced into the semi- ω -shaped recess 203 through the narrow throat 202 due to flame combustion expansion. When the piston moves downwards, due to the guiding effect of the semi-omega-shaped concave portion 203, the generated reverse squish flow strengthens the squish flow strength of the peripheral area of the combustion chamber, and the combustion rate of the mixed gas in the peripheral area of the combustion chamber can be effectively accelerated while the temperature of the bottom of the cylinder cover is reduced.