WO2023024965A1

WO2023024965A1 - Combustion chamber structure of gasoline engine and gasoline engine

Info

Publication number: WO2023024965A1
Application number: PCT/CN2022/112669
Authority: WO
Inventors: 韩令海; 刘耀东; 李金成; 陈海娥; 李显; 白洪江; 钱丁超
Original assignee: 中国第一汽车股份有限公司
Priority date: 2021-08-25
Filing date: 2022-08-16
Publication date: 2023-03-02
Also published as: CN113586227A

Abstract

A combustion chamber structure of a gasoline engine, comprising: a pre-combustion chamber (1) and a main combustion chamber (2); a bottom wall of the main combustion chamber comprises a piston top wall (22) and a boss (21) disposed on the piston top wall; the boss comprises a boss top wall (211) parallel to the piston top wall, and a first side wall (212) and a second side wall (213) spaced apart in the X-axis direction, wherein the first side wall is connected to the boss top wall and to a bottom wall of an intake valve pit, and the second side wall is connected to the boss top wall and to a bottom wall of an exhaust valve pit; avoidance grooves (214) are provided at intervals along the Y-axis direction of the boss; the pre-combustion chamber is uniformly provided with at least two spray holes (11) along the circumference thereof, the pre-combustion chamber is communicated with the main combustion chamber via the spray holes, wherein two spray holes are in one-to-one correspondence with the avoidance grooves. Additionally disclosed is a gasoline engine.

Description

Combustion chamber structure of gasoline engine and gasoline engine

This application claims the priority of a Chinese patent application with a filing date of August 25, 2021 and application number 202110979846.4, the entire contents of which are incorporated herein by reference.

technical field

The present application relates to the technical field of gasoline engine combustion systems, for example, to a combustion chamber structure of a gasoline engine and the gasoline engine.

Background technique

Among related technologies, internal combustion engines are constantly challenged by fuel consumption regulations, emission regulations and the development of new energy sources. Effective thermal efficiency has become an urgent need and development direction of the internal combustion engine industry. The gasoline engine can achieve multi-point and multi-surface ignition by using the pre-combustion chamber, so as to achieve fast and stable combustion. If it is matched with an ultra-high compression ratio (compression ratio greater than 16), the thermal efficiency can be significantly improved.

The cylinder head of the gasoline engine in the related art has a raised "roof" structure. If an ultra-high compression ratio is used, the top wall of the piston needs to be raised to meet the requirement of the compression ratio. Then the protruding structure of the top wall of the piston will cause the jet flame sprayed into the main combustion chamber from the pre-combustion chamber to contact the wall surface prematurely, resulting in hindered flame propagation, reduced combustion speed, and increased heat transfer loss.

Contents of the invention

The present application provides a combustion chamber structure of a gasoline engine and the gasoline engine, which can avoid the jet flame from impinging on the wall prematurely and improve the thermal efficiency under the premise of realizing an ultra-high compression ratio.

One embodiment provides a gasoline engine combustion chamber structure, including a pre-combustion chamber and a main combustion chamber surrounded by the top wall of the piston and the cylinder head when the piston runs to the top dead center, and the top wall of the piston is spaced along the X-axis direction. The intake valve pit and the exhaust valve pit, the piston top wall is provided with a boss, and the boss includes a boss top wall parallel to the piston top wall and a first side wall and a second side wall arranged at intervals along the X-axis direction. Two side walls, the first side wall is connected to the top wall of the boss and the bottom wall of the intake valve pit, and the second side wall is connected to the top wall of the boss and the exhaust valve pit The bottom wall of the boss is provided with avoidance grooves at intervals along the Y-axis direction; the pre-chamber is evenly arranged with at least two injection holes along the circumference, and the pre-chamber is connected to the main combustion chamber through the injection holes. The two nozzle holes correspond to the escape grooves one by one; the X-axis direction is perpendicular to the Y-axis direction.

An embodiment provides a gasoline engine, including the combustion chamber structure of the gasoline engine as described above.

Description of drawings

Fig. 1 is a partial sectional view of a combustion chamber structure of a gasoline engine provided by an embodiment of the present application;

Fig. 2 is a schematic diagram of the structure of the bottom wall of the main combustion chamber provided by an embodiment of the present application;

Fig. 3 is a schematic diagram of the jet flame position provided by an embodiment of the present application;

Fig. 4 is a schematic structural diagram of a main combustion chamber provided by an embodiment of the present application.

In the picture:

1. Pre-combustion chamber; 11. Injection hole; 12. Spark plug;

2, main combustion chamber; 21, boss; 211, boss top wall; 212, first side wall; 213, second side wall; 214, avoidance groove; 215, piston pit; 22, piston top wall; 23, cylinder head;

3. Jet flame.

Detailed ways

In the description of this application, it should be noted that unless otherwise specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection. Connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediary, and it can be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in this application in specific situations.

In this application, unless otherwise expressly specified and limited, a first feature being "on" or "under" a second feature may include direct contact between the first and second features, and may also include the first and second features Not in direct contact but through another characteristic contact between them. Moreover, "above", "above" and "above" the first feature on the second feature include that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is horizontally higher than the second feature. "Below", "beneath" and "under" the first feature to the second feature include that the first feature is directly below and obliquely below the second feature, or simply means that the first feature has a lower level than the second feature.

In recent years, internal combustion engines in related technologies have been continuously challenged by fuel consumption regulations, emission regulations and new energy development. The effective thermal efficiency of mainstream mass-produced gasoline engines is 38-41%. In the future, an effective thermal efficiency of 45% or even higher will become an urgent demand and development direction of the internal combustion engine industry. The gasoline engine can use the pre-combustion chamber to achieve multi-point and multi-surface ignition, so as to achieve fast and stable combustion, making up for the disadvantages of Miller cycle, EGR and lean burn technologies in combustion. 16), the thermal efficiency can be significantly improved.

As shown in Figures 1-4, the present embodiment provides a combustion chamber structure of a gasoline engine, including a pre-chamber 1 and a main combustion chamber 2, wherein the pre-chamber 1 is installed on the upper end of the main combustion chamber 2, and the pre-chamber The concrete form of 1 (comprising active type or passive type, the installation mode of pre-chamber 1 main body, pre-chamber 1 installation angle, the depth that pre-chamber 1 stretches into main combustion chamber 2 etc.) do not do too much restriction. In this embodiment, the pre-chamber 1 is installed directly above the center of the main combustion chamber 2 . In other embodiments, the installation position of the pre-chamber 1 may be slightly offset from the center of the main combustion chamber 2 . A spark plug 12 is installed in the pre-combustion chamber 1. After the spark plug 12 ignites the mixture, high-temperature and high-pressure gas is sprayed into the main combustion chamber 2 from the injection hole 11 of the pre-chamber 1, and the mixture in the main combustion chamber 2 is ignited for combustion.

Since the cylinder head combustion chamber of the mainstream gasoline engine in the related art has a raised "roof" shape, if an ultra-high compression ratio is to be realized, the piston top wall 22 needs to be raised to meet the requirement of the compression ratio. Therefore, in the combustion chamber structure of the gasoline engine provided in this embodiment, the bottom wall of the main combustion chamber 2 includes a piston top wall 22 and a boss 21 disposed on the piston top wall 22 . It should be noted that, for the convenience of description, a Cartesian coordinate system is defined, where the intersection point of the central axis of the cylinder and the plane where the bottom wall of the cylinder head 23 is located is the origin, the positive direction of the X-axis faces the intake side of the cylinder, and the positive direction of the Z-axis faces the cylinder head 23 Above, the positive Y axis is determined by the right-hand rule.

The main combustion chamber 2 provided in this embodiment is shown in Figure 2, and the piston top wall 22 is provided with exhaust valve pits and intake valve pits at intervals along the X-axis direction. In one embodiment, the intake valve pits are located on the X-axis In the positive direction, the exhaust valve pit is located in the negative direction of the X-axis, wherein there are two intake valve pits and two exhaust valve pits, and two intake valve pits and two exhaust valve pits are arranged at intervals along the Y-axis direction. The boss 21 located on the piston top wall 22 includes a boss top wall 211 parallel to the piston top wall 22, and a first side wall 212 and a second side wall 213 arranged at intervals along the X-axis direction, wherein the first side wall 212 is connected to The second side wall 213 is connected to the top wall 211 of the boss and the bottom wall of the exhaust valve pit. The compression ratio of the combustion chamber of the gasoline engine provided by the present embodiment is 17:1, correspondingly, the height of setting boss 21 (being the distance between boss top wall 211 and piston top wall 22) is 4.5m, compared with other In the embodiment, the height of the boss 21 is determined according to the required compression ratio, the greater the required compression ratio, the greater the height of the boss 21 .

In order to prevent the jet flame 3 sprayed from the nozzle holes 11 of the pre-chamber 1 into the main combustion chamber 2 from contacting the wall of the main combustion chamber 2 prematurely, resulting in hindered flame propagation and increased heat transfer loss, it is necessary to arrange the nozzle holes of the pre-chamber 1 reasonably 11 and 2 walls of the main combustion chamber. Therefore, the boss 21 provided in this embodiment is provided with two avoidance grooves 214 at intervals along the Y-axis direction, and the pre-combustion chamber 1 is evenly arranged with at least two injection holes 11 along the circumferential direction, wherein the two injection holes 11 and the avoidance grooves 214 The one-to-one correspondence prevents the jet flame 3 from impinging on the wall of the combustion chamber prematurely, and enhances the turbulent kinetic energy in the avoidance groove 214, so that after the jet flame 3 arrives, it can quickly ignite the mixed gas nearby and burn quickly. If more escape grooves 214 are provided, the area of the main combustion chamber 2 will be increased, which will affect the increase of the compression ratio. The two avoidance grooves 214 in this embodiment are arranged symmetrically along the first plane, wherein the first plane is plane Y=0, and the avoidance grooves 214 provided in this embodiment are spherical grooves, and the depth of the spherical grooves is 3mm. The maximum radius is 20mm, and the perpendicular line of the line connecting the centers of the two spherical grooves coincides with the center line of the pre-chamber 1 along the plane Y=0, or there is a small amount of offset, and the offset is 0-4mm.

In one embodiment, the number of injection holes 11 in the pre-combustion chamber 1 is an even number, which can conform to the characteristic that the combustion chamber of a gasoline engine is plane-symmetric. The number of nozzle holes 11 of the pre-combustion chamber 1 provided by the present embodiment is 6, as shown in Figure 3, the layout position of the nozzle holes 11 can be seen through the position of the jet flame 3, wherein two jet flames 3 are on the plane Z The projection on =0 is on a straight line, and the straight line is parallel to the Y axis. These two beams of jet flames 3 correspond to the escape grooves 214 one by one; among the remaining four beams of jet flames 3, two beams of jet flames 3 are located at the intake On the side of the door pit, two jet flames 3 are arranged on the side of the exhaust valve pit. The projections of two adjacent jet flames 3 on the plane Z=0 form an included angle of 60°, and each jet flame 3 is reasonably designed s position. If the number of injection holes 11 in the pre-chamber 1 is 4 or 2, the characteristics of multi-point and multi-face ignition of the pre-chamber 1 cannot be brought into full play; The limited size of the combustion chamber 1 will make it difficult to arrange the nozzle holes 11 and cause interference between adjacent jet flames 3 .

In one embodiment, as shown in Figure 4, the extension direction of the nozzle hole 11 forms an α angle with the plane Z=0, and the α angle is designed according to the angle between the intake and exhaust valves, and the range of the α angle is 15°-30° to ensure the jet flow The flame 3 is substantially evenly distributed between the cylinder head 23 and the piston top wall 22 .

In this embodiment, by setting the number and position of the nozzle holes 11 of the pre-combustion chamber 1, and the extension direction of the nozzle holes 11, the position of the jet flame 3 ejected from the nozzle holes 11 is reasonably arranged, and at the same time, the avoidance groove on the boss 21 is combined. The setting of 214, under the condition of ensuring the ultra-high compression ratio, prevents the jet flame 3 from hitting the wall prematurely, which hinders the flame propagation and increases the heat transfer loss.

In one embodiment, the top wall of the boss 21 is provided with a piston pit 215, and the piston pit 215 is arranged opposite to the pre-combustion chamber 1. The arrangement of the piston pit 215 can enhance the gas flow between the pre-chamber 1 and the main combustion chamber 2. , can promote the increase of turbulent kinetic energy in the pre-combustion chamber 1, and then improve the anti-exhaust gas and lean-burn ability, and stabilize the ignition. The piston pit 215 provided in this embodiment is a spherical pit with a depth of 2 mm and a maximum radius of 10 mm.

The present application increases the compression ratio by setting the boss 21 on the top wall of the piston, and increases the compression ratio by reducing the area of the main combustion chamber. The jet flame sprayed into the main combustion chamber 2 from the nozzle hole 11 of the pre-chamber 1 contacts the wall of the main combustion chamber 2 prematurely, causing the flame propagation to be hindered and the heat transfer loss to increase, thereby achieving an ultra-high compression ratio and improving thermal efficiency.

This embodiment also provides a gasoline engine, including the combustion chamber structure of the gasoline engine as described above, utilizing the space between the boss 21 and the cylinder head 23, and rationally and specifically arranging six evenly distributed jet flames 3 on the main combustion chamber. In the chamber 2, each jet flame 3 can make full use of its own space to develop, avoiding the premature impact of the jet flame 3 on the wall, thereby ensuring that the jet flame 3 entering the main combustion chamber 2 can be continuously and quickly spread, reducing the heat transfer loss of the jet flame 3 hitting the wall, and improving the thermal efficiency of the gasoline engine.

Claims

A combustion chamber structure of a gasoline engine, comprising a pre-combustion chamber (1) and a main combustion chamber (2) surrounded by a piston top wall (22) and a cylinder head (23) when the piston runs to the top dead center,

The piston top wall (22) is provided with an intake valve pit and an exhaust valve pit at intervals along the X-axis direction, and a boss (21) is provided on the piston top wall (22), and the boss (21) includes The boss top wall (211) parallel to the piston top wall (22) and the first side wall (212) and the second side wall (213) arranged at intervals along the X-axis direction, the first side wall (212) is connected The boss top wall (211) and the bottom wall of the intake valve pit, the second side wall (213) is connected to the boss top wall (211) and the bottom of the exhaust valve pit wall, the boss (21) is provided with avoidance grooves (214) at intervals along the Y-axis direction;

The pre-chamber (1) is uniformly arranged with at least two injection holes (11) along the circumference, and the pre-chamber (1) communicates with the main combustion chamber (2) through the injection holes (11), wherein The two spray holes (11) are in one-to-one correspondence with the avoidance groove (214);

The X-axis direction is perpendicular to the Y-axis direction.
The combustion chamber structure of a gasoline engine according to claim 1, wherein the number of the injection holes (11) is an even number.
The combustion chamber structure of a gasoline engine according to claim 2, wherein the number of the injection holes (11) is six.
The combustion chamber structure of a gasoline engine according to claim 1, wherein the extension direction of the injection hole (11) forms an angle α with the plane where the boss top wall (211) is located, and the angle α is 15°-30°.
The combustion chamber structure of a gasoline engine according to claim 1, wherein there are two avoidance grooves (214), and the two avoidance grooves (214) are arranged symmetrically along a first plane, and the first plane is a main combustion chamber. The plane of symmetry of the chamber (2) along the X-axis direction.
The combustion chamber structure of a gasoline engine according to claim 1, wherein the escape groove (214) is a spherical groove.
The combustion chamber structure of a gasoline engine according to claim 1, wherein a spark plug (12) is arranged in the pre-combustion chamber (1).
The combustion chamber structure of a gasoline engine according to any one of claims 1-7, wherein the boss top wall (211) is provided with a piston pit (215), and the piston pit (215) is connected to the pre-chamber (1) Facing the setting.
The combustion chamber structure of a gasoline engine according to claim 8, wherein the piston pit (215) is a spherical pit.
A gasoline engine, comprising the combustion chamber structure of the gasoline engine according to any one of claims 1-9.