CN214660530U - Gasoline engine and combustion chamber thereof - Google Patents

Abstract

The utility model discloses a gasoline engine and a combustion chamber thereof, wherein the combustion chamber comprises a cylinder, a cylinder head and a piston; the cylinder head is arranged on the cylinder, and a cylinder head pit which is right opposite to a piston channel of the cylinder is arranged at the bottom of the cylinder head; the piston can be accommodated in a piston channel of the cylinder in a vertically movable mode, a combustion chamber inner cavity is formed in the space between the top surface of the piston and a pit of the cylinder head, a piston concave surface which is sunken downwards is arranged on the top surface of the piston, and the piston concave surface is an asymmetric concave surface. The utility model discloses can effectively improve the combustion efficiency of oil-gas mixture in the combustion chamber inner chamber, greatly reduced harmful gas's production and emission are favorable to the environmental protection.

Description

Gasoline engine and combustion chamber thereof

Technical Field

The utility model relates to an engine field especially indicates a gasoline engine and combustion chamber thereof.

Background

The engine combustion chamber is an important part of the engine, is related to whether the oil-gas mixture is fully mixed or not and the combustion efficiency of the oil-gas mixture, and is one of main factors influencing the power performance of the engine. The higher the combustion efficiency of the oil-gas mixture gas is, the higher the energy conversion efficiency is, and the better the power performance of the engine is. In addition, the combustion efficiency of the oil-gas mixture has great influence on the exhaust emission of the engine, and the higher the combustion efficiency is, the less the exhaust emission of the combusted oil-gas mixture is.

In general, an engine combustion chamber is formed by a cylinder head pit on the lower bottom surface of a cylinder head and a piston top surface matched with the cylinder head pit. In the existing combustion chamber, a cylinder head pit is of a spherical crown structure, the cylinder head pit is over against a piston, and the top surface of the piston is a plane. When the piston of the existing combustion chamber is compressed, the tumble effect of the oil-gas mixed gas in the combustion chamber is poor, and the combustion efficiency of the oil-gas mixed gas is influenced.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a combustion chamber, it can improve oil-gas mixture's combustion efficiency. The utility model also provides a gasoline engine who has this combustion chamber.

In order to achieve the above purpose, the solution of the present invention is:

a combustion chamber comprising a cylinder, a cylinder head, and a piston; the cylinder forms a piston channel which penetrates through the cylinder from top to bottom, the cylinder head is arranged on the cylinder, a cylinder head pit which is right opposite to the piston channel is arranged at the bottom of the cylinder head, and the cylinder head pit is sunken upwards; an air inlet hole, an exhaust hole and a spark plug hole are arranged in the pit of the cylinder head, and the spark plug hole is positioned on the side of the central connecting line of the air inlet hole and the exhaust hole; the piston can be accommodated in a piston channel of the cylinder in a vertically movable manner, and a space between the top surface of the piston and a pit of the cylinder head forms an inner cavity of the combustion chamber; the plane parallel to the central line of the air inlet hole and the air outlet hole and passing through the central line of the piston is a transverse plane of the piston, and the plane perpendicular to the central line of the air inlet hole and the air outlet hole and passing through the central line of the piston is a longitudinal plane of the piston; the top surface of the piston is provided with a piston concave surface which is concave downwards; the piston concave surface is divided into an ignition side concave surface and a non-ignition side concave surface by taking the piston transverse surface as a boundary, the ignition side concave surface is close to a spark plug hole, the axial projection of the outer edge of the ignition side concave surface on the piston top surface is an ignition side outer curve, the axial projection of the outer edge of the non-ignition side concave surface on the piston top surface is a non-ignition side outer curve, two ends of the ignition side outer curve are respectively in transition connection with two ends of the non-ignition side outer curve, and the ignition side outer curve and the non-ignition side outer curve are symmetrically arranged relative to the piston transverse surface; the intersection line of the concave surface at the ignition side and the longitudinal surface of the piston is a central curve at the ignition side, the intersection line of the concave surface at the non-ignition side and the longitudinal surface of the piston is a central curve at the non-ignition side, the depth of the central curve at the ignition side at a position away from the transverse surface of the piston is greater than that of the central curve at the non-ignition side at a position away from the transverse surface of the piston, A is greater than zero and less than or equal to the maximum distance from the central curve at the ignition side to the transverse surface of the piston, and the maximum distance from the central curve at the ignition side to the transverse surface of the piston is equal to the maximum distance from the central curve at the non-ignition side to the transverse surface of the piston; the concave surface of the piston is divided into an air inlet side concave surface and an air outlet side concave surface by taking the longitudinal surface of the piston as a boundary, and the air inlet side concave surface and the air outlet side concave surface are respectively close to an air inlet hole and an air outlet hole; the intersection line of the concave surface at the air inlet side and the transverse surface of the piston is an air inlet side central curve, the intersection line of the concave surface at the air exhaust side and the transverse surface of the piston is an air exhaust side central curve, the point with the largest distance from the outer edge of the concave surface at the air inlet side to the longitudinal surface of the piston is positioned on the air inlet side central curve, the point with the largest distance from the outer edge of the concave surface at the air exhaust side to the longitudinal surface of the piston is positioned on the air exhaust side central curve, and the largest distance from the air inlet side central curve to the longitudinal surface of the piston is smaller than the largest distance from the air exhaust central curve to the longitudinal surface of the piston; the depth of the air inlet side central curve at a position B from the longitudinal surface of the piston is less than that of the air outlet side central curve at a position B from the longitudinal surface of the piston, and B is greater than zero and less than or equal to the maximum distance from the air inlet side central curve to the longitudinal surface of the piston.

The maximum distance from the central curve of the air inlet side to the longitudinal surface of the piston is 0.32-0.36 times of the diameter of the piston; the maximum distance from the central curve of the exhaust side to the longitudinal surface of the piston is 0.41-0.46 times of the diameter of the piston.

The depth from the central curve of the air inlet side to the position where the distance from the longitudinal surface of the piston is 0.25 times of the diameter of the piston is the first depth of the concave surface of the air inlet side, and the first depth of the concave surface of the air inlet side is more than or equal to 0.03 times of the diameter of the piston and less than or equal to 0.06 times of the diameter of the piston; the depth of the position, with the distance of 0.25 times the diameter of the piston, on the exhaust side concave surface is the first depth of the exhaust side concave surface, and the first depth of the exhaust side concave surface is greater than 1 time of the first depth of the air inlet side concave surface and less than or equal to 1.7 times of the first depth of the air inlet side concave surface.

The depth from the central curve of the non-ignition side to the position where the transverse surface of the piston is 0.125 times of the diameter of the piston is the first depth of the concave surface of the non-ignition side, and the first depth of the concave surface of the non-ignition side is more than or equal to 0.03 times of the diameter of the piston and less than or equal to 0.06 times of the diameter of the piston; the depth from the central curve of the ignition side to the position where the transverse surface of the piston is 0.125 times of the diameter of the piston is the first depth of the concave surface of the ignition side, and the first depth of the concave surface of the ignition side is more than or equal to 1.3 times of the first depth of the concave surface of the non-ignition side and less than or equal to 2 times of the first depth of the concave surface of the non-ignition side.

The periphery of the top surface of the piston forms a piston conical surface which is gradually expanded outwards from top to bottom; the lower periphery of the cylinder head pit forms a cylinder head conical surface which is gradually expanded from top to bottom.

The concave surface of the exhaust side is provided with an exhaust valve avoiding pit, and the top surface of the piston is provided with an intake valve avoiding pit.

A gasoline engine comprises the combustion chamber.

After the scheme is adopted, the utility model has the characteristics of it is following:

1. the utility model can guide the oil-gas mixture to the side of the concave surface of the ignition side through the concave surface of the piston, thereby enhancing the tumble strength and the turbulent kinetic energy of the oil-gas mixture in the inner cavity of the combustion chamber, and effectively improving the combustion efficiency of the oil-gas mixture in the inner cavity of the combustion chamber;

2. the piston concave surface of the utility model can increase the volume of the concave surface of the ignition side, thereby reducing the volume of the dead zone of the combustion chamber and further effectively improving the combustion efficiency of the oil-gas mixture in the inner cavity of the combustion chamber;

3. the utility model discloses when exhaust stroke, can make the gaseous stream of tumbling in the combustion chamber inner chamber than the strong department of the piston concave surface partial exhaust hole to make the piston can be better faster exhaust waste gas when exhaust stroke, improve the gas exchange rate of combustion chamber.

Drawings

Fig. 1 is a cross-sectional view of the present invention;

fig. 2 is a partial cross-sectional view of the present invention;

fig. 3 is a schematic view of a partial structure of the cylinder head according to the present invention;

fig. 4 is a schematic structural diagram of the piston of the present invention;

fig. 5 is a top view of the piston of the present invention;

fig. 6 is a cross-sectional view 1 of the piston of the present invention (the cross-section of fig. 6 is a piston transverse plane);

fig. 7 is a cross-sectional view 1 of the piston of the present invention (the cross-section of fig. 7 is the longitudinal plane of the piston);

fig. 8 is a comparison graph 1 of the air flow velocity field of the present invention when the piston is at the bottom dead center of the intake stroke in the prior art;

fig. 9 is a comparison graph of the air flow velocity field when the piston is at the bottom dead center of the intake stroke in the prior art in fig. 2;

fig. 10 is a graph comparing the air flow velocity field at 30 degrees before the top dead center of the compression stroke for the present invention and the prior art;

FIG. 11 is a comparison graph of the tumble strength curve of the present invention with that of the prior art;

FIG. 12 is a graph comparing the turbulent energy field of the present invention with the prior art when the piston is 30 degrees before top dead center of the compression stroke;

FIG. 13 is a graph comparing the intensity curves of turbulent kinetic energy of the present invention with the prior art;

description of reference numerals:

the length of the cylinder 1, the piston channel 11,

a cylinder head 2, a cylinder head pit 21, an intake hole 211, an exhaust hole 212, a spark plug hole 213, a cylinder head cone 214,

the shape of the piston 3, the concave surface 31 of the piston,

the ignition-side concave surface 311, the ignition-side outer curve 3111, the ignition-side center curve 3112,

non-firing side concave surface 312, non-firing side outer curve 3121, non-firing side center curve 3122,

an intake side concave surface 313, an intake side center curve 3131,

the exhaust side concave surface 314, the exhaust side center curve 3141,

a piston cone 32, an exhaust valve avoiding pit 33, an intake valve avoiding pit 34,

the center line L between the intake hole 211 and the exhaust hole 212,

the inner cavity S of the combustion chamber is,

a piston transverse face F1, a piston longitudinal face F2,

the maximum distance L1 from the firing side center curve 3112 to the piston transverse plane F1,

the maximum distance L2 from the non-firing side center curve 3122 to the piston lateral surface F1,

the maximum distance L3 from the intake side center curve 3131 to the piston longitudinal plane F2,

the maximum distance L4 from the exhaust side center curve 3141 to the piston longitudinal plane F2,

the diameter of the piston is D, and,

an intake side concave surface first depth H1, an exhaust side concave surface first depth H2, a firing side concave surface first depth H3, and a non-firing side concave surface first depth H4.

Detailed Description

In order to further explain the technical solution of the present invention, the present invention is explained in detail by the following embodiments.

As shown in fig. 1 to 7, the present invention discloses a combustion chamber, which includes a cylinder 1, a cylinder head 2, and a piston 3; the cylinder 1 forms a piston channel 11 which penetrates through the cylinder up and down, the cylinder head 2 is installed on the cylinder 1, a cylinder head pit 21 which is opposite to the piston channel 11 is arranged at the bottom of the cylinder head 2, the cylinder head pit 21 is sunken upwards, an air inlet hole 211, an air outlet hole 212 and a spark plug hole 213 are formed in the cylinder head pit 21, the air inlet hole 211 is used for installing an air inlet valve, the air outlet hole 212 is used for installing an exhaust valve, the spark plug hole 213 is used for installing a spark plug, and the spark plug hole 213 is positioned on the side of a central connecting line L of the air inlet hole 211 and the air outlet hole 212; the piston 3 is accommodated in the piston channel 11 of the cylinder 1 in a manner of moving up and down, a space between the top surface of the piston 3 and the cylinder head pit 21 forms a combustion chamber inner cavity S, and the top surface of the piston 3 is provided with a piston concave surface 31 which is concave downwards.

In the present invention, a plane parallel to the center line L of the air inlet hole 211 and the air outlet hole 212 and passing through the center line of the piston 3 is a piston transverse plane F1, and a plane perpendicular to the center line L of the air inlet hole 211 and the air outlet hole 212 and passing through the center line of the piston 3 is a piston longitudinal plane F2.

As shown in fig. 5 and 7, the concave piston surface 31 is divided into a concave ignition-side surface 311 and a concave non-ignition-side surface 312 by a piston transverse surface F1, the concave ignition-side surface 311 is close to the spark plug hole 213, an axial projection of an outer edge of the concave ignition-side surface 311 on the top surface of the piston 3 is an outer ignition-side curve 3111, an axial projection of an outer edge of the concave non-ignition-side surface 312 on the top surface of the piston 3 is an outer non-ignition-side curve 3121, two ends of the outer ignition-side curve 3111 are respectively connected with two ends of the outer non-ignition-side curve 3121 in a transition manner, and the outer ignition-side curve 3111 and the outer non-ignition-side curve 3121 are symmetrically arranged with respect to the piston transverse surface F1; the intersection of the ignition-side concave surface 3111 and the piston longitudinal surface F2 is an ignition-side center curve 3112, the intersection of the non-ignition-side concave surface 312 and the piston longitudinal surface F2 is a non-ignition-side center curve 3122, the depth of the ignition-side center curve 3112 at a position a from the piston transverse surface F1 is greater than the depth of the non-ignition-side center curve 3122 at a position a from the piston transverse surface F1, a is greater than zero and equal to or less than the maximum distance L1 from the ignition-side center curve 3112 to the piston transverse surface F1, and the maximum distance L1 from the ignition-side center curve 3122 to the piston transverse surface F1 is equal to the maximum distance L2 from the non-ignition-side center curve 3122 to the piston transverse surface F1. Wherein the depth of the center curve 3112 at the position A from the piston transverse plane F1 is greater than the depth of the center curve 3122 at the position A from the piston transverse plane F1, so that the depth of the concave surface 311 at the ignition side is greater than the depth of the concave surface 312 at the non-ignition side, so that the tumble intensity and the turbulent kinetic energy of the gas-oil mixture in the combustion chamber cavity S can be enhanced, and the strongest position of the gas-oil mixture in the combustion chamber cavity S with the strongest tumble intensity and turbulent kinetic energy is close to the spark plug hole, and the gas-oil mixture is fully mixed at the strongest position, so that the ignition effect of the gasoline engine is good; in addition, the depth of the ignition side concave surface 311 is greater than that of the non-ignition side concave surface 312, and meanwhile, the volume of the ignition side concave surface 3111 can be increased, so that the dead zone volume of the combustion chamber is reduced, and the combustion efficiency of the oil-gas mixture in the inner cavity S of the combustion chamber is effectively improved.

As shown in fig. 5 and 6, the concave surface 31 of the piston is divided into a concave surface 313 on the intake side and a concave surface 314 on the exhaust side by a piston longitudinal surface F2, and the concave surface 313 on the intake side and the concave surface 314 on the exhaust side are respectively close to the intake hole 211 and the exhaust hole 212; the intersection line of the intake side concave surface 313 and the piston transverse surface F1 is an intake side center curve 3131, and the intersection line of the exhaust side concave surface 314 and the piston transverse surface F is an exhaust side center curve 3141; the point where the outer edge of the intake side concave surface 313 is the greatest distance from the piston longitudinal surface F2 is on the intake side center curve 3131 such that the maximum distance L3 from the intake side center curve 3131 to the piston longitudinal surface F2 is the maximum distance from the outer edge of the intake side concave surface 313 to the piston longitudinal surface F2; the point at which the outer edge of the discharge side concave surface 314 is the greatest distance from the piston longitudinal surface F2 is on the discharge side center curve 3141 such that the maximum distance L4 from the discharge side center curve 3141 to the piston longitudinal surface F2 is the maximum distance from the outer edge of the discharge side concave surface 314 to the piston longitudinal surface F2; the maximum distance L3 from the intake side center curve 3131 to the piston longitudinal surface F2 is smaller than the maximum distance L4 from the exhaust center curve 3141 to the piston longitudinal surface F2, so that the piston concave surface 31 is biased toward the exhaust side concave surface 314 side; the depth of the intake side center curve 3131 at a position B from the piston longitudinal plane F2 is less than the depth of the exhaust side center curve 3141 at a position B from the piston longitudinal plane F2, B being greater than zero and equal to or less than the maximum distance L3 of the intake side center curve 3131 to the piston longitudinal plane F2. Wherein the utility model discloses a maximum distance L3 of side central curve 3131 that admits air to piston longitudinal surface F2 is less than exhaust central curve 3141 to the maximum distance L4 of piston longitudinal surface F2, the degree of depth that side central curve 3131 that admits air was located apart from piston longitudinal surface F2 for B is less than the degree of depth that side central curve 3141 was located apart from piston longitudinal surface F2 for B' S position, so set up, make the engine when the exhaust stroke, make the gaseous tumble of combustion chamber cavity S in the strong department of department partial exhaust hole 212 of combustion chamber, thereby make piston 3 can be better faster exhaust waste gas when the exhaust stroke, improve the gas exchange rate of combustion chamber.

Preferably, in the present invention, the maximum distance L3 from the central curve 3131 on the air inlet side to the longitudinal plane F2 of the piston is 0.32 to 0.36 times the diameter D of the piston; the maximum distance L4 from the exhaust side center curve 3141 to the piston longitudinal surface F2 is 0.41-0.46 times of the diameter D of the piston. The maximum distance L3 from the central curve 3131 of the air inlet side to the longitudinal surface F2 of the piston is 0.32-0.36 times of the diameter D of the piston, so that the strong tumble flow of the oil-gas mixed gas cannot be too close to the inner wall of the piston channel 11 when the engine is in an air inlet stroke, and the phenomenon that the inner wall of the piston channel 11 is impacted is avoided; and the maximum distance L4 from the exhaust side center curve 3141 to the piston longitudinal surface F2 is 0.41-0.46 times of the diameter D of the piston, so that the strong tumble flow of gas in the combustion chamber inner cavity S can be deflected to the exhaust hole 212 during the exhaust stroke of the engine, and the exhaust is facilitated.

Preferably, in the present invention, a depth from the intake side central curve 3131 to a position where the distance F2 from the piston longitudinal surface is 0.25 times of the piston diameter D is an intake side concave surface first depth H1, and the intake side concave surface first depth H1 is greater than or equal to 0.03 times of the piston diameter D and less than or equal to 0.06 times of the piston diameter D; the depth of the exhaust side concave surface 3141 from the piston longitudinal surface F2 to 0.25 times of the piston diameter is an exhaust side concave surface first depth H2, and the exhaust side concave surface first depth H2 is greater than 1 time of the intake side concave surface first depth H1 and is less than or equal to 1.7 times of the intake side concave surface first depth H1. The utility model discloses so set up, can be so that the degree of depth of piston concave surface 31 is less to ensure piston 3's intensity, guaranteed piston 3's rigidity, avoid piston 3 to warp at the during operation and strike cylinder 1.

Preferably, in the present invention, the depth from the center curve 3112 on the non-ignition side to the position where the piston transverse surface F1 is 0.125 times the piston diameter D is the first depth H4 of the non-ignition side concave surface, and the first depth H4 of the non-ignition side concave surface is not less than 0.03 times and not more than 0.06 times the piston diameter D; the depth of the ignition side center curve 3122 from the position where the piston transverse surface F1 is 0.125 times the piston diameter D is the ignition side concave surface first depth H3, and the ignition side concave surface first depth H3 is 1.3 times or more and 2 times or less of the non-ignition side concave surface first depth H4. The utility model discloses so set up, can be so that the degree of depth of piston concave surface 31 is less to ensure piston 3's intensity, guaranteed piston 3's rigidity, avoid piston 3 to warp at the during operation and strike cylinder 1.

As shown in fig. 1 to 4, the top circumference of the piston 3 forms a piston conical surface 32 which is gradually enlarged from top to bottom and outwards, the lower circumference of the cylinder head pit 21 forms a cylinder head conical surface 214 which is gradually enlarged from top to bottom and outwards, when the piston 3 is in a compression stroke, the piston conical surface 32 and the cylinder head conical surface 214 are matched to form a squish flow effect, so that airflow around the combustion chamber inner cavity S flows to the center of the combustion chamber inner cavity S, thereby being beneficial to increasing the flame diffusion intensity during ignition and improving the combustion efficiency of the oil-gas mixed gas. The concave surface 31 of the piston 3 can be directly cast and formed, and the conical surface 32 of the piston can be formed by CNC machining, so that the volume of the top of the piston 3 can be accurately controlled by CNC machining. Additionally the utility model discloses a set up piston conical surface 32 and can ensure piston 3's intensity, guaranteed piston 3's rigidity, avoid piston 3 to warp at the during operation and strike cylinder 1.

As shown in fig. 4 and 5, the exhaust side concave surface 314 is provided with an exhaust valve escape pit 33 for escaping an exhaust valve, and the top surface of the piston 3 is provided with an intake valve escape pit 34 for escaping an intake valve, so that the piston 3 can move upward as much as possible.

Comparing the technical effect difference between the prior art and the solution of the present invention by experimental simulation, selecting a calibration point (ignition time is-15 CA) to calculate the working condition, comparing the prior art with the simulation result of the solution of the present invention by using three-dimensional simulation calculation software, please refer to FIGS. 8 to 13, FIG. 8 is a comparison graph of the air flow velocity field when the piston is at the bottom dead point of the intake stroke with the prior art 1, FIG. 9 is a comparison graph of the air flow velocity field when the piston is at the bottom dead point of the intake stroke with the prior art 2, FIG. 10 is a comparison graph of the air flow velocity field when the piston is 30 degrees before the top dead point of the compression stroke, FIG. 11 is a comparison graph of the tumble strength curve between the present invention and the prior art, FIG. 12 is a comparison graph of the turbulent kinetic energy field when the piston is 30 degrees before the top dead point of the compression stroke, fig. 13 is a comparison graph of the intensity curve of turbulent kinetic energy of the present invention and the prior art. In fig. 11 and 13, the dotted line represents the variation curve of the solution (i.e. new model) of the present invention, and the solid line represents the variation curve of the prior art (i.e. original model).

As can be seen from figure 8, the utility model discloses when the piston is in intake stroke bottom dead center, can make the mixed gas of oil and gas produce more strong tumble flow intensity than prior art in the combustion chamber inner chamber through piston concave surface 31.

As shown in fig. 9, when the piston is at the bottom dead center of the intake stroke, the oil-gas mixture can be guided to the side of the ignition side concave surface 311 through the concave surface 31 of the piston; and the prior art makes the gas-oil mixture shunt to both sides for the gas-oil mixture is concentrated inadequately.

As shown in fig. 10, when the piston of the present invention is 30 degrees before the top dead center of the compression stroke, the oil-gas mixture can be guided to the side of the concave surface 311 of the ignition side through the concave surface 31 of the piston; and the prior art makes the gas-oil mixture shunt to both sides for the gas-oil mixture is concentrated inadequately.

As can be seen from FIG. 12, the piston concave surface 31 of the present invention enables the mixed gas to generate stronger tumble strength in the combustion chamber cavity than the prior art.

As can be seen from FIG. 13, the turbulent kinetic energy intensity of the present invention is obviously superior to the prior art, and the present invention has strong turbulent kinetic energy in 30 degrees before the compression top dead center, which is favorable for the ignition energy diffusion benefit.

As can be seen from fig. 9 to 13, the movable concave surface 31 of the present invention enables the present invention to enhance the tumble strength of the oil-gas mixture in the combustion chamber cavity S during both the intake stroke and the compression stroke; in the intake stroke and the compression stroke, the most strong tumble strength of the oil-gas mixture is positioned on one side of the concave surface 311 on the ignition side, so that the ignition effect of the gasoline engine can be effectively improved.

The utility model also provides a gasoline engine, it includes foretell combustion chamber, makes this gasoline engine's combustion efficiency high through foretell combustion chamber.

The above embodiments and drawings are not intended to limit the form and style of the present invention, and any suitable changes or modifications made by those skilled in the art should not be construed as departing from the scope of the present invention.

Claims (7)

1. A combustion chamber, characterized by: comprises a cylinder, a cylinder head and a piston;

the cylinder forms a piston channel which penetrates through the cylinder from top to bottom, the cylinder head is arranged on the cylinder, a cylinder head pit which is right opposite to the piston channel is arranged at the bottom of the cylinder head, and the cylinder head pit is sunken upwards; an air inlet hole, an exhaust hole and a spark plug hole are arranged in the pit of the cylinder head, and the spark plug hole is positioned on the side of the central connecting line of the air inlet hole and the exhaust hole;

the piston can be accommodated in a piston channel of the cylinder in a vertically movable manner, and a space between the top surface of the piston and a pit of the cylinder head forms an inner cavity of the combustion chamber; the plane parallel to the central line of the air inlet hole and the air outlet hole and passing through the central line of the piston is a transverse plane of the piston, and the plane perpendicular to the central line of the air inlet hole and the air outlet hole and passing through the central line of the piston is a longitudinal plane of the piston; the top surface of the piston is provided with a piston concave surface which is concave downwards;

the piston concave surface is divided into an ignition side concave surface and a non-ignition side concave surface by taking the piston transverse surface as a boundary, the ignition side concave surface is close to a spark plug hole, the axial projection of the outer edge of the ignition side concave surface on the piston top surface is an ignition side outer curve, the axial projection of the outer edge of the non-ignition side concave surface on the piston top surface is a non-ignition side outer curve, two ends of the ignition side outer curve are respectively in transition connection with two ends of the non-ignition side outer curve, and the ignition side outer curve and the non-ignition side outer curve are symmetrically arranged relative to the piston transverse surface; the intersection line of the concave surface at the ignition side and the longitudinal surface of the piston is a central curve at the ignition side, the intersection line of the concave surface at the non-ignition side and the longitudinal surface of the piston is a central curve at the non-ignition side, the depth of the central curve at the ignition side at a position away from the transverse surface of the piston is greater than that of the central curve at the non-ignition side at a position away from the transverse surface of the piston, A is greater than zero and less than or equal to the maximum distance from the central curve at the ignition side to the transverse surface of the piston, and the maximum distance from the central curve at the ignition side to the transverse surface of the piston is equal to the maximum distance from the central curve at the non-ignition side to the transverse surface of the piston;

the concave surface of the piston is divided into an air inlet side concave surface and an air outlet side concave surface by taking the longitudinal surface of the piston as a boundary, and the air inlet side concave surface and the air outlet side concave surface are respectively close to an air inlet hole and an air outlet hole; the intersection line of the concave surface at the air inlet side and the transverse surface of the piston is an air inlet side central curve, the intersection line of the concave surface at the air exhaust side and the transverse surface of the piston is an air exhaust side central curve, the point with the largest distance from the outer edge of the concave surface at the air inlet side to the longitudinal surface of the piston is positioned on the air inlet side central curve, the point with the largest distance from the outer edge of the concave surface at the air exhaust side to the longitudinal surface of the piston is positioned on the air exhaust side central curve, and the largest distance from the air inlet side central curve to the longitudinal surface of the piston is smaller than the largest distance from the air exhaust central curve to the longitudinal surface of the piston; the depth of the air inlet side central curve at a position B from the longitudinal surface of the piston is less than that of the air outlet side central curve at a position B from the longitudinal surface of the piston, and B is greater than zero and less than or equal to the maximum distance from the air inlet side central curve to the longitudinal surface of the piston.

2. The combustor of claim 1, wherein: the maximum distance from the central curve of the air inlet side to the longitudinal surface of the piston is 0.32-0.36 times of the diameter of the piston; the maximum distance from the central curve of the exhaust side to the longitudinal surface of the piston is 0.41-0.46 times of the diameter of the piston.

3. The combustor of claim 1, wherein: the depth from the central curve of the air inlet side to the position where the distance from the longitudinal surface of the piston is 0.25 times of the diameter of the piston is the first depth of the concave surface of the air inlet side, and the first depth of the concave surface of the air inlet side is more than or equal to 0.03 times of the diameter of the piston and less than or equal to 0.06 times of the diameter of the piston;

the depth of the position, with the distance of 0.25 times the diameter of the piston, on the exhaust side concave surface is the first depth of the exhaust side concave surface, and the first depth of the exhaust side concave surface is greater than 1 time of the first depth of the air inlet side concave surface and less than or equal to 1.7 times of the first depth of the air inlet side concave surface.

4. The combustor of claim 1, wherein: the depth from the central curve of the non-ignition side to the position where the transverse surface of the piston is 0.125 times of the diameter of the piston is the first depth of the concave surface of the non-ignition side, and the first depth of the concave surface of the non-ignition side is more than or equal to 0.03 times of the diameter of the piston and less than or equal to 0.06 times of the diameter of the piston;

the depth from the central curve of the ignition side to the position where the transverse surface of the piston is 0.125 times of the diameter of the piston is the first depth of the concave surface of the ignition side, and the first depth of the concave surface of the ignition side is more than or equal to 1.3 times of the first depth of the concave surface of the non-ignition side and less than or equal to 2 times of the first depth of the concave surface of the non-ignition side.

5. The combustor of claim 1, wherein: the periphery of the top surface of the piston forms a piston conical surface which is gradually expanded outwards from top to bottom; the lower periphery of the cylinder head pit forms a cylinder head conical surface which is gradually expanded from top to bottom.

6. The combustor of claim 1, wherein: the concave surface of the exhaust side is provided with an exhaust valve avoiding pit, and the top surface of the piston is provided with an intake valve avoiding pit.

7. A gasoline engine, characterized in that: comprising a combustion chamber according to claim 1.

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