CN113404615A - Arc top piston top, arc top piston and combustion chamber - Google Patents

Abstract

The present disclosure provides an arc top piston top, arc top piston and combustion chamber, arc top piston top includes: the arc pit area is a bowl-shaped pit and is positioned at the center of the top of the arc-top piston; the height of the first end of the conical surface convex area is higher than that of the second end of the conical surface convex area, the first end of the conical surface convex area is contacted with the outer edge of the arc pit area, and the second end of the conical surface convex area extends to the edge of the top of the arc top piston; the two conical surface convex areas are respectively positioned on the front side and the rear side of the arc pit area, and the two conical surface convex areas are symmetrically arranged relative to the arc pit area. The arc top piston top can be applied to a large-cylinder-diameter high-compression-ratio engine, the air flow movement speed in the air inlet stroke of the engine can be increased to a large extent, the compression stroke and the turbulent kinetic energy at the tail end of the compression stroke are improved, and the detonation phenomenon of the large-cylinder-diameter high-compression-ratio engine in the related technology is effectively solved.

Description

Arc top piston top, arc top piston and combustion chamber

Technical Field

The present disclosure relates to the field of engines, and more particularly to a curved crown piston crown, a curved crown piston, and a combustion chamber.

Background

The engine is a main emission source of atmospheric pollutants and is also an important source of carbon emission, the annual average petroleum consumption of the engine accounts for more than 60% of the total petroleum consumption in China, and the carbon dioxide emission of the engine exceeds 10% of the total carbon emission in China. With the continuous promotion of the green development concept, the engine faces the challenge of increasingly strict emission and oil consumption regulations, and the development of a high-thermal-efficiency near-zero-emission engine becomes the primary target of the academic and engineering circles. At present, the development of gasoline engines with high thermal efficiency mainly depends on technical means such as high compression ratio, external cooling EGR (exhaust gas recirculation), low friction loss and the like. Compared with a diesel engine, the large-displacement gasoline engine has the advantages of low noise, low cost and the like, and has larger market space in the market-dividing fields of high-end business buses, large pickup trucks and the like. Compared with a complex V-shaped multi-cylinder arrangement type, the scheme with the in-line large cylinder diameter has the advantage of cost. However, for a large-cylinder-diameter gasoline engine, the flame propagation distance is longer, the knocking tendency is greater, and the technical challenge of realizing efficient development in combination with technologies such as high compression ratio and the like exists. The technical reasons lead the development of the in-line large-cylinder-diameter high-efficiency gasoline engine to be very difficult.

The top of the piston is used as an important component in a combustion chamber of the engine, and directly influences the mixing uniformity, flame propagation speed, heat release rate, heat transfer loss and knocking tendency of the engine, thereby influencing the performance of the engine. The root of the detonation is that the tail end gas mixture is self-ignited, and the larger the cylinder diameter is, the higher the compression ratio is, the greater the detonation tendency is.

The top of the piston of the conventional PFI gasoline engine is mostly designed to be flat, so that the efficient organization of oil-gas mixing and the improvement of turbulent kinetic energy distribution are difficult, the occurrence of knocking phenomenon is easily caused, the power of the engine is reduced, and the fuel economy of the engine is poor. The irregular pits are formed in the center of the top of the piston of some types and act together with other structures, so that airflow enters a combustion chamber to form a plane vortex, turbulent kinetic energy is enhanced, quality of mixed gas is improved, and detonation tendency is reduced.

In addition, the top of the existing special-shaped piston is generally designed into an irregular shape, is difficult to realize by processing, is often formed by casting, has poor surface roughness, causes certain loss to intake tumble flow, and simultaneously needs to be cooperatively applied with direct injection (GDI) in a cylinder, so that certain problems exist in the application of the special-shaped piston to a large-cylinder-diameter PFI gasoline engine.

Therefore, how to improve the flow of mixed gas in a combustion chamber of the engine by further optimizing the top structure of the piston, effectively inhibit the knocking tendency of the large-cylinder-diameter high-compression-ratio gasoline engine, and realize the autonomous design and development of the in-line large-cylinder-diameter high-efficiency engine is a technical problem which needs to be solved at present.

Disclosure of Invention

Technical problem to be solved

In the prior art, knocking is usually suppressed by accelerating combustion speed, reducing in-cylinder temperature and the like. The inventor finds that the mixing of the fuel and the air in the cylinder can be effectively enhanced by optimizing the structure of the combustion chamber, the combustion speed is accelerated, the knocking is inhibited, and the EGR tolerance is improved. The applicant finds that the piston top combustion chamber structure is optimized through design, the mixed gas flow in a cylinder can be better improved, the tumble ratio and the turbulent kinetic energy of the combustion chamber are improved, the knocking tendency of the large-cylinder-diameter high-compression-ratio gasoline engine is effectively inhibited, the flame propagation speed is accelerated, the combustion duration is shortened, the combustion stability is improved, and finally the dynamic property and the economical efficiency of the engine are improved. The present disclosure provides a curved crown piston crown and a curved crown piston and combustion chamber using the same to at least solve the problems of the prior art described above.

(II) technical scheme

To achieve the above objects, the present disclosure provides an arc crown piston crown comprising: the arc pit area is a bowl-shaped pit and is positioned at the center of the top of the arc-top piston; the height of the first end of the conical surface convex area is higher than that of the second end of the conical surface convex area, the first end of the conical surface convex area is contacted with the outer edge of the arc pit area, and the second end of the conical surface convex area extends to the edge of the top of the arc top piston; the two conical surface convex areas are respectively positioned on the front side and the rear side of the arc pit area, and the two conical surface convex areas are symmetrically arranged relative to the arc pit area.

In some embodiments of the present disclosure, further comprising:

the first flat top area is a plane, one end of the first flat top area is in contact with the outer edge of the left side of the arc-shaped pit area, the other end of the first flat top area extends to the edge of the top of the arc-shaped top piston, and the first flat top area is located between the two conical surface convex areas;

and the second flat top area is a plane and is coplanar with the first flat top area, one end of the second flat top area is contacted with the outer edge of the right side of the arc-shaped pit area, the other end of the second flat top area extends to the edge of the top of the arc-shaped top piston, and the second flat top area is positioned between the two conical surface convex areas.

In some embodiments of the present disclosure, a vertical distance from an outer edge of the arc pit area to a pit bottom of the arc pit area is 5-7 mm, and a radius of the arc pit area is 75-85 mm.

In some embodiments of the present disclosure, the included angle between the conical generatrix of the conical convex area and the plane of the first flat top area or the second flat top area is 18 ° to 22 °.

In some embodiments of the present disclosure, the first plateau region comprises:

the two inlet valve avoiding areas are arc-shaped pits and are respectively arranged at the intersection of the first flat top area and the two conical surface convex areas; wherein, the included angle between the normal line of the bottom of the arc-shaped concave pit in the two inlet valve avoiding areas and the vertical direction is 17-20 degrees.

In some embodiments of the present disclosure, the second flat top region comprises:

the two exhaust valve avoiding areas are arc-shaped pits and are respectively arranged at the intersection of the second flat top area and the two conical surface convex areas; wherein, the included angle between the pit bottom normal of the arc-shaped pit in the two exhaust valve avoiding areas and the vertical direction is 20-24 degrees.

The present disclosure also provides an arc crown piston, comprising:

a crown piston crown as disclosed above;

the outer diameter of the head is the same as that of the top of the arc top piston, the outer diameter is 95-100 mm, and the head is located below the top of the arc top piston;

and the skirt part is fixedly connected with the lower part of the head part.

In some embodiments of the present disclosure, the head comprises:

the oil guide groove is formed in the outer ring of the head part;

and the piston ring is sleeved in the oil guide groove.

In some embodiments of the present disclosure, the skirt further comprises

And the connecting rod pin hole is suitable for rotatably connecting the connecting rod of the arc top piston.

The present disclosure also provides a combustion chamber comprising:

a cylinder wall;

the arc top piston is arranged inside the cylinder wall and is coaxially and slidably connected with the cylinder wall;

and the cylinder cover is fixedly connected with the upper opening of the cylinder wall and forms a closed cavity with the cylinder wall.

(III) advantageous effects

According to the technical scheme, the arc top piston and the combustion chamber using the same have at least one or part of the following beneficial effects:

(1) the arc-shaped concave pit area and the two conical surface convex areas on the top of the arc-shaped top piston can optimize the air flow movement form in the cylinder to a greater extent, increase the air flow movement speed in the air inlet stroke of the engine, can be applied to the development of a large-cylinder-diameter high-efficiency engine, and effectively solves the knocking phenomenon of the large-cylinder-diameter high-compression-ratio engine in the related technology.

(2) The conical surface convex area and the flat top area can jointly realize the optimization of the air flow motion form to form a larger-scale tumble, the piston compression process can lead the tumble to be broken and converted into stronger turbulent kinetic energy during the work doing period of the combustion chamber, the combustion is accelerated, the detonation tendency is obviously improved, the application problem of the high compression ratio technology of the large-cylinder-diameter engine is solved, and the fuel economy of the engine can be effectively improved.

(3) The crown piston top and cone surface protrusion structure in the present disclosure, through cooperating with the engine air flue and matching, does not rely on the GDI system, is applicable to lower cost air flue injection (PFI). The application working condition limit of the high compression ratio technology of the traditional air passage injection PFI gasoline engine can be effectively expanded, and the inhibition of knocking and the improvement of fuel economy can be realized under lower injection pressure.

(4) The edge structure of the top of the arc-top piston in the disclosure can enable fuel in a combustion chamber to form turbulence in the edge area of the top of the piston, is particularly suitable for the design of a large cylinder diameter, can effectively enhance fuel flow and heat exchange of sensitive areas such as the outer edge of the combustion chamber and the like, and improves the detonation tendency.

(5) The structure at the top of the arc top piston is easy to machine and manufacture by using a mirror surface machining process, the flow loss can be reduced, the flow strength of fuel in a cylinder is increased, the combustion speed is increased, the fuel consumption is reduced, the low-speed power of an engine is enhanced, and the driving feeling and the fuel economy of the whole vehicle are improved.

Drawings

FIG. 1 is a perspective view of a crown of an arc top piston in an embodiment of the present disclosure;

FIG. 2 is a top view of a crown of the arc top piston in an embodiment of the present disclosure;

FIG. 3 is a cross-sectional view taken along A-A of FIG. 2;

FIG. 4 is a cross-sectional view taken along line B-B of FIG. 2;

FIG. 5 is a cross-sectional view taken along the line C-C of FIG. 2;

FIG. 6 is a front view of a curved top piston in an embodiment of the present disclosure;

FIG. 7 is a perspective view of a flat-top combustor;

FIG. 8 is a perspective view of a contoured combustion chamber;

FIG. 9 is a graph comparing transient tumble flows for an arc top piston combustion chamber with a conventional flat top piston combustion chamber in an embodiment of the present disclosure;

FIG. 10 is a graph comparing transient turbulence energy for a curved topped piston combustion chamber in an embodiment of the present disclosure with a conventional flat topped piston combustion chamber.

[ description of main reference numerals in the drawings ] of the embodiments of the present disclosure

1-a first plateau region;

2-arc pit area;

3-a conical surface convex area;

31-a first end of a conical raised area;

32-a second end of the conical raised area;

4-an exhaust valve avoiding area;

5-an intake valve avoidance zone;

6-a second plateau region;

7-top;

8-a head;

9-a skirt;

10-oil guide grooves;

11-a piston ring;

12-connecting rod pin hole.

Detailed Description

The present disclosure provides an arc top piston top, arc top piston and combustion chamber, its arc top piston top includes: an arc-shaped pit area and two conical surface convex areas. The arc pit area is a bowl-shaped pit and is positioned at the center of the top of the arc top piston; the first end of the conical surface convex area is higher than the second end of the conical surface convex area, the first end of the conical surface convex area is contacted with the outer edge of the arc pit area, and the second end of the conical surface convex area extends to the edge of the top of the arc top piston; the two conical surface convex areas are respectively positioned on the front side and the rear side of the arc pit area, and are symmetrically arranged relative to the arc pit area. The arc top piston top can be applied to a large-cylinder-diameter high-compression-ratio engine, the air flow movement speed in the air inlet stroke of the engine can be increased to a large extent, the compression stroke and the turbulent kinetic energy at the tail end of the compression stroke are improved, and the detonation phenomenon of the large-cylinder-diameter high-compression-ratio engine in the related technology is effectively solved.

For the purpose of promoting a better understanding of the objects, aspects and advantages of the present disclosure, reference is made to the following detailed description taken in conjunction with the accompanying drawings. This disclosure may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity, and like reference numerals designate like elements throughout.

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood that the description is illustrative only and is not intended to limit the scope of the present disclosure. In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the disclosure. It may be evident, however, that one or more embodiments may be practiced without these specific details. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present disclosure.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The terms "comprises," "comprising," and the like, as used herein, specify the presence of stated features, steps, operations, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, or components.

All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise defined. It is noted that the terms used herein should be interpreted as having a meaning that is consistent with the context of this specification and should not be interpreted in an idealized or overly formal sense.

Where a convention analogous to "at least one of A, B and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B and C" would include but not be limited to systems that have a alone, B alone, C alone, a and B together, a and C together, B and C together, and/or A, B, C together, etc.). Where a convention analogous to "A, B or at least one of C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B or C" would include but not be limited to systems that have a alone, B alone, C alone, a and B together, a and C together, B and C together, and/or A, B, C together, etc.).

The present disclosure provides an arc top piston crown, as shown in fig. 1, comprising: an arc-shaped pit area 2 and two conical convex areas 3. The arc pit area 2 is a bowl-shaped pit and is positioned at the center of the top of the arc top piston. The first end 31 of the conical surface convex area is higher than the second end 32 of the conical surface convex area, the first end 31 of the conical surface convex area is contacted with the outer edge of the arc pit area 2, and the second end 32 of the conical surface convex area extends to the edge of the top of the arc top piston; the two conical surface convex areas 3 are respectively positioned on the front side and the rear side of the arc pit area 2, and the two conical surface convex areas 3 are symmetrically arranged relative to the arc pit area 2.

The combined design of the arc-shaped pit area 2 and the conical surface convex area 3 can increase the airflow movement speed in the air inlet stroke of the engine to a greater extent.

As shown in fig. 1 and 2, the arc-top piston top further includes: a first plateau 1 and a second plateau 6. The first flat top area 1 is a plane, one end of the first flat top area 1 is in contact with the outer edge of the left side of the arc-shaped pit area 2, the other end of the first flat top area 1 extends to the edge of the top of the arc-shaped piston, and the first flat top area 1 is located between the two conical surface convex areas 3. The second flat top area 6 is a plane and is coplanar with the first flat top area 1, one end of the second flat top area 6 is contacted with the outer edge of the right side of the arc-shaped pit area 2, the other end of the second flat top area 6 extends to the edge of the top of the arc-shaped top piston, and the second flat top area 6 is positioned between the two conical surface convex areas 3.

The conical surface convex area 3 can be combined with the flat top area, the optimization of the air flow motion form is realized, large-scale tumble flow is formed, the tumble flow can be broken and converted into stronger turbulent kinetic energy in the piston compression process during the work doing period of the combustion chamber, the combustion is accelerated, the detonation tendency is further obviously improved, the application problem of the high compression ratio technology of the large-cylinder-diameter engine is solved, and the fuel economy of the combustion chamber of the engine can be effectively improved.

The combined design of the arc pit area 2 and the conical surface bulge can increase the airflow movement speed of the air inlet stroke of the combustion chamber to a greater extent and improve the tumble strength; at the moment of the compression end of the combustion chamber, by means of the special structural design of the conical surface convex area 3 at the top of the piston, tumble flow can be effectively broken and converted into stronger turbulent kinetic energy, and the combustion process is accelerated. Especially in the knock sensitive areas such as the outer edge of the combustion chamber, compared with the traditional technical scheme, the local micro-turbulence can be formed, the flow and heat exchange of the area are effectively enhanced, and the knocking tendency is obviously improved.

As shown in fig. 2 and 3, the first flat top region 1 includes: two intake valve avoidance zones 5. The intake valve avoiding area 5 is an arc-shaped pit, and the two intake valve avoiding areas 5 are respectively arranged at the intersection of the first flat top area 1 and the two conical surface convex areas 3; wherein, the included angle instrument between the normal line of the bottom of the arc-shaped concave pit in the two inlet valve avoiding areas 5 and the vertical direction is 17-20 degrees. The second flat top region 6 includes: two exhaust valve avoidance zones 4. The exhaust valve avoiding areas 4 are arc-shaped pits, and the two exhaust valve avoiding areas 4 are respectively arranged at the intersection of the second flat top area 6 and the two conical surface convex areas 3; wherein, the included angle beta between the pit bottom normal of the arc-shaped pit in the two exhaust valve avoiding areas 4 and the vertical direction is 20-24 degrees.

FIG. 4 is a cross-sectional view taken along the direction B-B of FIG. 2, in which the vertical distance d from the outer edge of the arc-shaped pit region 2 to the bottom of the arc-shaped pit region 2 is 5 to 7mm, and the radius R of the arc-shaped pit region 2 is 75 to 85 mm.

Fig. 5 shows a cross-sectional view along the direction C-C of fig. 2, in which the included angle y between the generatrix of the conical surfaces of the two conical surface convex regions 3 and the plane of the first flat top region 1 or the second flat top region 6 is 18 ° to 22 °.

According to the arc-top piston, the top part can form micro-turbulence in the edge area, the flow and heat exchange of the arc-top piston are effectively enhanced, and the detonation tendency is greatly improved.

The present disclosure also provides a curved crown piston, as shown in fig. 6, which includes the aforementioned crown 7, head 8 and skirt 9. The outer diameter of head 8 is the same with the outer diameter of top 7, and this outer diameter be 95 ~ 100mm, and this head 8 is located top 7 below, and skirt portion 9 links firmly with the below of head 8.

As shown in fig. 6, the head 8 of the arc-topped piston includes: an oil guide groove 10 arranged on the outer ring of the head part 8 and a piston ring 11 sleeved and arranged in the oil guide groove 10.

The skirt portion 9 of the arc top piston includes a connecting rod pin hole 12 for rotatably connecting the connecting rod of the arc top piston. The connecting rod drives the arc top piston to move up and down to do work externally by being connected with a crankshaft of the engine.

The oil guide groove 10 is used for installing a piston ring 11 of the arc top piston to form a lubricating oil path, so that the arc top piston is lubricated. Specifically, the outer ring of the piston ring 11 contacts with the inner wall of the cylinder wall in the combustion chamber, and the piston ring 11 guides the residual fuel on the cylinder wall into the oil guide groove 10 along with the sliding of the arc-top piston to complete the lubrication of the arc-top piston, thereby prolonging the service life of the arc-top piston.

The distance between the first flat top area 1 or the second flat top area 6 of the arc top piston top 7 and the center of the connecting rod pin hole 12 is 32-36 mm.

An air inlet valve avoiding area 5 and an air outlet valve avoiding area 4 of the arc top piston top 7 are areas for ensuring the safety distance between the piston and the air valve, and the whole areas are of arc structures and are respectively intersected with the arc pit area 2, the conical surface convex area 3, the first flat top area 1 and the second flat top area 6. The central normal lines of the intake valve avoiding area 5 and the exhaust valve avoiding area 4 are coaxial with the central line of the engine valve, wherein the radius of the intake valve avoiding area 5 is 20-22 mm, and the distance between the bottom of the arc-shaped pit in the intake valve avoiding area 5 and the connecting rod pin hole 12 is 38-42 mm; the radius of the exhaust valve avoiding area 4 is 17-19 mm, and the distance between the bottom of the arc-shaped pit in the exhaust valve avoiding area 4 and the connecting rod pin hole 12 is 41-45 mm.

The diameter range of the piston used by the arc top piston structure is 95-100 mm.

In addition, fig. 7 and 8 respectively show a top-flat combustion chamber perspective view and a special-shaped combustion chamber perspective view in the related art, the top structures of the two pistons cannot be machined, the pistons need to be machined in a casting mode, the casting production process is multiple, the process control is complex, and the rejection rate is high.

In contrast, the first flat top area 1, the second flat top area 6, the arc-shaped pit area 2 and the conical surface convex area 3 in the top 7 of the arc-topped piston in the present disclosure may adopt a mirror finishing process, the design structure is easy to process, and the surface roughness precision may reach more than ra 3.2.

The mirror surface processing technology can reduce the flow loss and realize better oil-gas mixing effect. The flow intensity in the cylinder is increased, and the knocking is further improved. By the technical measures, the application problem of the high compression ratio technology of the large-cylinder-diameter gasoline engine can be effectively solved, the fuel consumption rate is effectively reduced, the low-speed power performance is enhanced, and the driving feeling and the fuel economy of the whole vehicle are obviously improved.

The present disclosure also provides a combustion chamber using the above arc-top piston, the combustion chamber including: cylinder walls, a curved-roof piston, and a cylinder head. The arc top piston is arranged in the cylinder wall and is coaxially and slidably connected with the cylinder wall; the cylinder cover is fixedly connected with the upper opening of the cylinder wall and forms a closed cavity with the cylinder wall.

Through the structure that designs into the easy processing's of major scale arc pit district 2 with arc top piston top central area, two conical surface protruding district 3 and first flat top district 1 and the second flat top district 6 combined action simultaneously, can show the optimization air current motion form, form the tumble flow of bigger scale, especially at the combustion chamber compression end moment, rely on conical surface protruding district 3 class of designs at piston top, can effectively make the tumble flow broken, turn into stronger turbulent kinetic energy, the combustion process accelerates, show and improve the detonation tendency, the problem of application of big cylinder diameter gasoline engine high compression ratio technique has been solved, fuel economy nature has effectively been promoted.

As can be seen in fig. 9, the transient tumble ratio of the curved-topped piston combustion chamber of the present disclosure is significantly higher than that of the conventional flat-topped piston combustion chamber; as can be seen in fig. 10, the transient turbulence energy of the curved-topped piston combustion chamber of the present disclosure is significantly greater than the transient tumble ratio of a conventional flat-topped piston combustion chamber. Therefore, the arc top piston combustion chamber provided by the disclosure has a good combustion effect, and the power of the engine is strong.

The design of the piston top combustion chamber directly influences the oil-gas mixing uniformity, flame propagation speed, heat release rate heat transfer loss and detonation tendency of the engine, and further influences the performance of the engine. Through the design optimization combustion chamber structure, the combustion characteristics of the gasoline engine can be better improved, the tumble ratio and the turbulent kinetic energy of the combustion chamber are improved, the flame propagation speed is accelerated, the combustion duration is shortened, the combustion stability is improved, the detonation tendency is reduced, and finally the dynamic property and the economical efficiency of the engine are improved.

The combustion chamber applying the arc top piston can realize the implementation of a high compression ratio scheme without depending on a GDI direct injection system, effectively reduces the development cost of the system, and makes the use of a large-cylinder-diameter high-compression ratio gasoline engine in the fields of commercial vehicles and the like possible. The combustion chamber disclosed by the invention is independent of a GDI system, is developed aiming at lower-cost air passage injection (PFI), and can be applied to high compression ratio models through the optimized design of the combustion chamber at the top of the piston under lower injection pressure and the cooperative matching of the air passage and the like, so that the application range of the high compression ratio technology of the traditional PFI gasoline engine is effectively expanded.

It should also be noted that directional terms, such as "upper", "lower", "front", "rear", "left", "right", and the like, used in the embodiments are only directions referring to the drawings, and are not intended to limit the scope of the present disclosure. Throughout the drawings, like elements are represented by like or similar reference numerals. In the event of possible confusion for understanding of the present disclosure, conventional structures or configurations will be omitted, and the shapes and sizes of the components in the drawings do not reflect actual sizes and proportions, but merely illustrate the contents of the embodiments of the present disclosure.

Unless otherwise indicated, the numerical parameters set forth in the specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the present disclosure. In particular, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about". Generally, the expression is meant to encompass variations of ± 10% in some embodiments, 5% in some embodiments, 1% in some embodiments, 0.5% in some embodiments by the specified amount.

The use of ordinal numbers such as "first," "second," "third," etc., in the specification and claims to modify a corresponding element does not by itself connote any ordinal number of the element or any ordering of one element from another or the order of manufacture, and the use of the ordinal numbers is only used to distinguish one element having a certain name from another element having a same name.

In addition, unless steps are specifically described or must occur in sequence, the order of the steps is not limited to that listed above and may be changed or rearranged as desired by the desired design. The embodiments described above may be mixed and matched with each other or with other embodiments based on design and reliability considerations, i.e., technical features in different embodiments may be freely combined to form further embodiments.

The above-mentioned embodiments are intended to illustrate the objects, aspects and advantages of the present disclosure in further detail, and it should be understood that the above-mentioned embodiments are only illustrative of the present disclosure and are not intended to limit the present disclosure, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present disclosure should be included in the scope of the present disclosure.

Claims (10)

1. A curved top piston crown comprising:

the arc pit area is a bowl-shaped pit and is positioned at the center of the top of the arc-top piston;

the height of the first end of the conical surface convex area is higher than that of the second end of the conical surface convex area, the first end of the conical surface convex area is contacted with the outer edge of the arc pit area, and the second end of the conical surface convex area extends to the edge of the top of the arc top piston; the two conical surface convex areas are respectively positioned on the front side and the rear side of the arc pit area, and the two conical surface convex areas are symmetrically arranged relative to the arc pit area.

2. The crown of claim 1, further comprising:

the first flat top area is a plane, one end of the first flat top area is in contact with the outer edge of the left side of the arc-shaped pit area, the other end of the first flat top area extends to the edge of the top of the arc-shaped top piston, and the first flat top area is located between the two conical surface convex areas;

and the second flat top area is a plane and is coplanar with the first flat top area, one end of the second flat top area is contacted with the outer edge of the right side of the arc-shaped pit area, the other end of the second flat top area extends to the edge of the top of the arc-shaped top piston, and the second flat top area is positioned between the two conical surface convex areas.

3. The curved-topped piston crown as set forth in claim 1, wherein a vertical distance from an outer edge of the curved pit area to a pit bottom of the curved pit area is 5-7 mm, and a radius of the curved pit area is 75-85 mm.

4. The arc top piston crown of claim 1, wherein the included angle between the generatrix of the conical surface of the conical convex area and the plane of the first flat top area or the second flat top area is 18 ° to 22 °.

5. The crown piston crown of claim 2, wherein the first flat crown area comprises:

the two inlet valve avoiding areas are arc-shaped pits and are respectively arranged at the intersection of the first flat top area and the two conical surface convex areas; wherein, the included angle between the normal line of the bottom of the arc-shaped concave pit in the two inlet valve avoiding areas and the vertical direction is 17-20 degrees.

6. The arc crown piston crown of claim 2, wherein the second flat crown area comprises:

the two exhaust valve avoiding areas are arc-shaped pits and are respectively arranged at the intersection of the second flat top area and the two conical surface convex areas; wherein, the included angle between the pit bottom normal of the arc-shaped pit in the two exhaust valve avoiding areas and the vertical direction is 20-24 degrees.

7. An arc top piston comprising:

the curved top piston crown of any one of claims 1 to 6;

the outer diameter of the head is the same as that of the top of the arc top piston, the outer diameter is 95-100 mm, and the head is located below the top of the arc top piston;

and the skirt part is fixedly connected with the lower part of the head part.

8. The arc crown piston of claim 7, wherein the head comprises:

the oil guide groove is formed in the outer ring of the head part;

and the piston ring is sleeved in the oil guide groove.

9. The crown piston of claim 7, wherein the skirt further comprises

And the connecting rod pin hole is suitable for rotatably connecting the connecting rod of the arc top piston.

10. A combustion chamber, comprising:

a cylinder wall;

the arc top piston of any one of claims 7 to 9, disposed inside the cylinder wall in sliding coaxial connection therewith;

and the cylinder cover is fixedly connected with the upper opening of the cylinder wall and forms a closed cavity with the cylinder wall.

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