CN114233464A

CN114233464A - Combustion system, engine and combustion control method

Info

Publication number: CN114233464A
Application number: CN202111530459.9A
Authority: CN
Inventors: 尧命发; 杨瑞; 郑尊清; 刘恒; 王浒
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2021-12-14
Filing date: 2021-12-14
Publication date: 2022-03-25

Abstract

The invention relates to the technical field of internal combustion engines, and provides a combustion system, which comprises a machine body; a piston installed in the body; the cylinder cover is arranged at the opening position of the engine body, and the cylinder cover, the engine body and the piston limit a first combustion chamber; the first combustion part is arranged in the middle of the cylinder cover and used for injecting fuel into the first combustion chamber; the second combustion portion, set up the position that is located first combustion portion side on the cylinder head and communicate with first combustion chamber, the second combustion portion includes: a second combustion chamber formed in the cylinder head, fuel of the second combustion chamber being combusted prior to fuel of the first combustion chamber; and the jet hole is formed on the surface of the cylinder cover opposite to the piston and used for forming a fuel bundle formed by igniting the fuel in the first combustion chamber by jet flame. The present disclosure also provides for an engine including a combustion system, a monitoring unit, and a control unit. And the combustion control method of the engine comprises the step of controlling the ignition timing and the oil injection timing of the spark plug to form cooperative coordination according to the position of the piston of the engine.

Description

Combustion system, engine and combustion control method

Technical Field

The invention relates to the technical field of internal combustion engines, in particular to a combustion system, an engine and a combustion control method.

Background

Methanol, dimethyl ether, biodiesel, synthetic natural gas, polyoxymethylene dimethyl ether (PODE), ammonia and the like, and particularly low-carbon or zero-carbon fuels such as methanol, synthetic natural gas and ammonia have great potential in reducing carbon emissions.

However, the low-carbon and zero-carbon fuels have low activity and are not easy to combust. Applications in the field of internal combustion engines are generally carried out in two ways by igniting a premixed gas or a dual fuel combustion (e.g. diesel/natural gas dual fuel).

The premixed ignition type diesel engine has the advantages that the premixed ignition type diesel engine is low in combustion efficiency, poor in small-load combustion stability, too high in large-load pressure rise rate, even knocks and the like, and the engine can only adopt a low compression ratio due to the limitation of the knocks, so that the thermal efficiency is poor. The dual-fuel mode still needs to burn diesel oil, so that the effect of reducing carbon emission is poor, and the structure of the engine is complicated by adopting two sets of fuel oil systems. In addition, because the fuel has lower activity and is not easy to ignite and burn, the compression self-ignition mode can cause the difficult problems of poor combustion stability under the small-load working condition, even 'fire' and too rough work under the large-load working condition, and simultaneously, the compression ratio of the engine is overhigh, and the running stability and the reliability are poor.

Disclosure of Invention

In view of the above technical problems, the present invention provides a combustion system, an engine and a combustion control method, which are used to at least partially solve the above technical problems.

One aspect of the present disclosure provides a combustion system, a housing; a piston installed in the body; the cylinder cover is arranged at the opening position of the machine body, and the cylinder cover, the machine body and the piston define a first combustion chamber; the first combustion part is arranged in the middle of the cylinder cover, is communicated with the first combustion chamber and is used for injecting fuel into the first combustion chamber; and a second combustion unit provided in the cylinder head at a position beside the first combustion unit and communicating with the first combustion chamber, the second combustion unit including: a second combustion chamber formed in the cylinder head, fuel of the second combustion chamber being combusted prior to fuel of the first combustion chamber; and the jet hole is formed on the surface of the cylinder cover opposite to the piston and used for enabling the fuel combusted in the second combustion chamber to form the jet flame so as to ignite the fuel beam formed by the fuel in the first combustion chamber and enable the fuel beam in the first combustion chamber to be combusted in a diffusion combustion mode.

According to an embodiment of the present disclosure, further comprising: an air inlet passage formed on the cylinder head; the exhaust passage is formed on the other radial side of the cylinder cover which is symmetrical to the air inlet passage; an intake valve is mounted in the air inlet channel and can be opened and closed; an exhaust valve is arranged in the exhaust passage in an openable and closable manner.

According to the embodiment of the disclosure, a connecting line formed by the first combustion part and the second combustion part in a radial plane of the cylinder head is perpendicular to a connecting line formed by the intake passage and the exhaust passage.

According to the embodiment of the disclosure, the first combustion part comprises a first fuel injector which is arranged at the middle position of the cylinder cover and extends into the first combustion chamber along the axial direction of the cylinder cover; and the first end of the first oil injector in the first combustion chamber in the axial direction is provided with spray holes along the circumferential direction.

According to the embodiment of the disclosure, a groove is formed on the surface of the piston opposite to the cylinder cover, the surface of the groove is smoothly arranged, and fuel injected from the injection hole of the first fuel injector forms a vortex group through the surface of the groove.

According to an embodiment of the present disclosure, the second combustion portion further includes a second injector provided in the second combustion chamber to inject fuel into the second combustion chamber; and an ignition plug provided in the second combustion chamber to ignite the fuel injected by the second injector.

There is also provided according to another aspect of the present disclosure an engine comprising: the combustion system; a monitoring unit adapted to monitor the position of the piston; and a control unit adapted to control an ignition timing of the second combustion portion in accordance with a position of the piston; wherein the second combustion portion includes a second injector and a spark plug.

There is also provided a combustion control method of an engine according to another aspect of the present disclosure, including: monitoring a position of a piston of the engine; and controlling the ignition timing of the spark plug according to the position of the piston.

According to an embodiment of the present disclosure, wherein monitoring the position of the piston of the engine comprises obtaining the position of the piston from an angle of a crank angle of a crankshaft associated with the piston in one working cycle of the piston.

According to the embodiment of the disclosure, the controlling of the ignition timing of the spark plug according to the position of the piston comprises the steps of injecting fuel by the second fuel injector during the process that the piston approaches the top dead center again in one working cycle of the piston, then igniting the spark plug, and controlling the first fuel injector to inject the fuel into the first combustion chamber based on the ignition timing of the spark plug so as to realize the ignition of the fuel injected by the first fuel injector by jet flame.

The utility model provides a combustion system, device forms first combustion chamber through organism, piston and cylinder cap cooperation, sets up first combustion portion and second combustion portion in the cylinder cap respectively. The first combustion part is used for inputting fuel into the first combustion chamber, the second combustion part is used for pre-burning a part of fuel, and then a jet flow flame formed by the pre-burned fuel ignites a fuel bundle formed by the fuel in the first combustion chamber and enables the fuel bundle in the first combustion chamber to be combusted in a diffusion combustion mode.

The present disclosure further provides an engine, which has the advantages of the combustion system, and controls the time of oil injection, the opening and closing of the valve, and the ignition timing of the spark plug based on the position and the state of the piston through the cooperation of the monitoring unit and the control unit.

The present disclosure also provides a combustion control method to achieve relatively stable combustion at relatively small loads and relatively high combustion efficiency; under the condition of large load, the occurrence of detonation can be effectively prevented.

Drawings

FIG. 1 is a cross-sectional schematic view of a combustion system according to an exemplary embodiment of the present disclosure;

FIG. 2 is a cross-sectional schematic view of another angle of the illustrative embodiment shown in FIG. 1;

FIG. 3 is a state diagram of a fuel injection state of the combustion system of the exemplary embodiment shown in FIG. 1;

FIG. 4 is a bottom view of the head portion of the exemplary embodiment shown in FIG. 1;

FIG. 5 is a functional block diagram of an engine according to an exemplary embodiment of the present disclosure; and

FIG. 6 is a flow chart of a combustion control method according to the present disclosure.

Reference numerals

1. A piston;

2. a body;

3. a cylinder cover;

4. a first combustion chamber;

5. spraying a hole;

6. a first fuel injector;

7. an injector end cap;

8. a second combustion chamber;

9. a spark plug;

10. a second fuel injector;

11. a jet hole;

12. an air inlet channel;

13. an intake valve;

14. an exhaust valve; and

15. and (4) an exhaust passage.

Detailed Description

In order that the objects, technical solutions and advantages of the present invention will become more apparent, the present invention will be further described in detail with reference to the accompanying drawings in conjunction with the following specific embodiments.

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.).

FIG. 1 is a cross-sectional schematic view of a combustion system according to an exemplary embodiment of the present disclosure; FIG. 2 is a cross-sectional schematic view of another angle of the illustrative embodiment shown in FIG. 1; FIG. 3 is a state diagram of a fuel injection state of the combustion system of the exemplary embodiment shown in FIG. 1; FIG. 4 is a bottom view of the head portion of the exemplary embodiment shown in FIG. 1; FIG. 5 is a functional block diagram of an engine according to an exemplary embodiment of the present disclosure; FIG. 6 is a flow chart of a combustion control method according to the present disclosure.

The present disclosure provides a combustion apparatus, as shown in fig. 1 to 4, the above combustion system, including: a machine body 2; a piston 1 installed in the body 2; a cylinder head 3 mounted in an open position of the body 2, said body 2, piston 1 and cylinder head 3 defining a first combustion chamber 4; the middle part of the cylinder cover 3 is provided with a first combustion part used for injecting fuel into the first combustion chamber 4, and the cylinder cover 3 is also provided with a second combustion part used for forming jet flame and igniting the fuel in the first combustion chamber 4; wherein the second combustion portion includes a second combustion chamber 8 formed in the cylinder head 3 and an injection hole 11 formed in a surface of the cylinder head 3 opposite to the piston 1, and the fuel in the second combustion chamber 8 combusts prior to the fuel in the first combustion chamber 4, and forms a jet flame in the first combustion chamber 4 through the injection hole 11 to ignite the fuel in the first combustion chamber 4.

In detail, the fuel used in the first combustion section and the second combustion section may be identical, for example, a large amount of fuel is introduced in the first combustion section, and a smaller amount of fuel is introduced in the second combustion section, and the jet flame generated after the smaller amount of fuel is combusted is used to ignite the fuel in the first combustion chamber. It should be understood that embodiments of the present disclosure are not limited thereto.

For example, the fuel used in the first and second combustion sections is not uniform. The first combustion part is filled with a first fuel which is not easy to combust, the second combustion part is filled with a second fuel which is easy to combust, and jet flame generated after the second fuel is combusted is used for igniting the first fuel in the first combustion chamber.

According to the embodiment of the present disclosure, the combustion apparatus further includes an intake passage 12 formed in the cylinder head 3, and an exhaust passage 15 provided in the cylinder head 3 symmetrically to the intake passage 12. An intake valve 13 is provided in the intake passage 12 to be openable and closable, and an exhaust valve 14 is provided in the exhaust passage 15 to be openable and closable.

According to the embodiment of the present disclosure, a line formed by the first combustion portion and the second combustion portion and a line formed by the intake passage 12 and the exhaust passage 15 are perpendicular to each other in a plane formed by the radial direction of the cylinder head 3. So that the second combustion part forms an offset design relative to the first combustion part, which is beneficial to realize the design purpose of the second combustion part igniting the first combustion part by designing parameters (including but not limited to position, diameter, length of jet hole and the like) of the jet hole 5 and the jet hole 11.

According to the embodiment of the present disclosure, as shown in fig. 3 and 4, the first combustion portion includes a first injector 6 that is provided in the middle of the cylinder head 3 and extends into the first combustion chamber 4 in the axial direction of the cylinder head 3. Wherein, the first end of the first fuel injector 6 in the axial direction of the first combustion chamber 4 is provided with a spray hole 5 along the circumferential direction.

Specifically, the number of the injection holes 5 is six to eight, and the six injection holes 5 are uniformly spaced in the circumferential direction.

In detail, the first injector 6 is fixed to the end cap by an injector end cap 7.

Further, the number of injection holes 5 may be designed according to the actual fuel injection demand and flow rate. It should be understood that embodiments of the present disclosure are not limited thereto.

For example, the number of the injection holes 5 is other number.

Furthermore, the position of the injection hole 5 can also be designed according to the type of fuel and the relative position with the second combustion part.

According to the embodiment of the present disclosure, a groove is formed on the surface of the piston 1 facing the cylinder head 3, the surface of the groove is smoothly arranged, and fuel injected from the injection hole 5 of the first injector forms a vortex cluster through the surface of the groove.

In detail, a groove is formed on the surface of the piston facing the cylinder cover, and round transition is smoothly arranged at the groove bottom of the groove.

Furthermore, the middle part of the groove and the orthographic projection position of the first combustion part form a convex part, and the convex part and the groove bottom of the groove are integrally formed. So that the fuel injected into the groove is stopped by the groove bottom of the groove and extends to the radial outside along the groove bottom to form a vortex group. It should be understood that embodiments of the present disclosure are not limited thereto.

For example, the shape of the recess should be designed depending on the position of the first combustion portion and the position of the injection hole 5 formed by the first injector 6.

Also, since the piston 1 is moved along the body 2, the shape of the groove should also be designed according to the position of the piston 1 relative to the body 2.

For example, the shape of the groove should be such that, when the piston 1 is moved up to a certain position, the fuel injected by the first injector 6 forms what kind of a vortex in the groove as a design purpose.

According to the embodiment of the present disclosure, as shown in fig. 3 and 4, the second combustion portion includes the second combustion chamber 8 formed in the cylinder head 3, the second injector 10 and the ignition plug 9 are provided in the second combustion chamber 8, and an injection hole 11 for communicating the second combustion chamber with the first combustion chamber is further provided in the surface of the cylinder head 3 facing the piston 1, so that the fuel combusted in the second combustion chamber 8 forms a jet flame.

In detail, the lower end portion of the second combustion chamber 8 is located inside the first combustion chamber 4.

Further, the second combustion chamber 8 is an offset second combustion chamber with respect to the first combustion chamber 4.

Furthermore, in the plurality of jet holes 11 communicating with the second combustion chamber 8, each jet hole 11 can be individually designed according to actual requirements, for example, the position, number and parameters (including but not limited to angle, aperture and length) of the jet hole 11, and the like, so as to satisfy the requirement that the second combustion chamber 8 can form a jet flame and the jet flame can effectively ignite the fuel in the first combustion chamber 4.

For example, the number of jet holes 11 coincides with the number of injection holes 5 of the first injector 6. The jet flame formed by the jet hole 11 partially overlaps with the path of the fuel ejected from the nozzle hole 5.

For example, the number of ejection holes 11 is not the same as the number of ejection holes 5.

For example, the downward inclination angle of the jet hole 11 near the first injector 6 is smaller than that of the jet hole 11 on the other side, so that the jet flames from both sides can contact with the corresponding fuel and effectively ignite, thereby improving the ignition effect of the flame jet on the fuel in the first combustion chamber 4.

For example, the angle and position of the jet holes 11 coincide.

For example, the speed of the fuel ejected from the jet hole 11 and the like are controlled by the overall design of parameters such as the length, the hole diameter, and the angle of the jet hole 11.

There is also provided according to another aspect of the present disclosure an engine, as shown in fig. 5, including a monitoring unit and a control unit. Wherein, the monitoring unit is used for monitoring the position of the piston 1, and the control unit is used for controlling the injection time of the first injector 6 and/or the second injector 10, the opening and closing of the intake valve 13 and/or the exhaust valve 14 and the ignition timing of the spark plug 9 according to the position of the piston 1.

There is also provided a combustion control method of an engine according to another aspect of the present disclosure, as shown in fig. 6, including: monitoring the position of the piston 1 of the engine; and controlling the ignition timing of the ignition plug in accordance with the position of the piston 1.

Monitoring the position of the piston 1 of the engine according to the embodiment of the present disclosure includes obtaining the position of the piston 1 according to the angle of the crank angle of the crankshaft linked with the piston 1 in one working cycle of the piston 1.

According to the embodiment of the present disclosure, controlling the ignition timing of the ignition plug 9 according to the position of the piston 1 includes, during one working cycle of the piston 1, the second injector 10 injecting fuel while the piston 1 is again close to the top dead center, then the ignition plug 9 igniting, and controlling the first injector 6 to inject fuel into the first combustion chamber 4 based on the ignition timing of the ignition plug 9 to achieve effective ignition of the fuel injected by the first injector by the jet flame.

In detail, the piston 1 firstly descends from the top dead center, when the intake valve 13 is opened, the exhaust valve 14 is in a closed state, and fresh air enters the first combustion chamber 4 and the second combustion chamber 8 through the air inlet channel; when the piston 1 goes beyond the bottom dead center, the intake valve 13 is closed, the piston 1 moves upwards to compress the air in the cylinder, the temperature and the pressure of the air are continuously increased, the second fuel injector 10 starts to inject fuel, and the injected fuel is mixed with the air in the second combustion chamber 8 to form uniform mixed air; when the piston 1 moves to a position close to the top dead center, the ignition plug 9 ignites and ignites the combustible mixture in the second combustion chamber 9, the temperature and the pressure in the second combustion chamber 8 are increased rapidly due to the heat release of the fuel combustion, so that the pressure difference between the second combustion chamber 8 and the first combustion chamber 4 is increased gradually, and the combustion flame in the second combustion chamber 8 is ejected from the jet hole 11 under the action of the pressure difference to form jet flame; moreover, the first injector 6 also starts to inject fuel, and due to the higher injection pressure, the fuel spray will be injected to the edge of the first combustion chamber 4, so that the jet flame can ignite the combustible mixture at the end of the spray; after the combustible mixed gas at the spray tail end of the first combustion chamber 4 is ignited, diffusion combustion flame is formed, and a large amount of heat is released by fuel combustion to push the piston 1 to move downwards and output mechanical work; when the piston 1 moves to a position close to the bottom dead center, the exhaust valve 14 is opened, and the piston 1 moves upwards to remove waste gas in a combustion chamber, so that the whole working process is completed.

According to the combustion system, the engine and the combustion control method provided by the disclosure, 1, the low-activity fuel in the first combustion chamber is ignited by the jet flame formed by the second combustion chamber, so that the low-activity fuel can realize diffusion combustion, and the diffusion combustion has higher efficiency, so that the combustion system and the engine provided by the disclosure have higher combustion efficiency and thermal efficiency. 2. The low-activity fuel in the first combustion chamber is ignited by the jet flame, so that the ignition and combustion stability of the low-activity fuel under a small-load working condition can be obviously improved. 3. Compared with the premixing ignition mode in the prior art, the method can effectively avoid the problem of overhigh boosting rate under the working condition of large load. 4. The fuel quantity entering the first combustion chamber and/or the second combustion chamber can be adjusted according to the real-time change of the load, so that the stable combustion of the combustion system under the full working condition can be effectively improved. And then make the fuel quantity that increases the second combustion chamber under the light load condition, strengthen the pilot action of efflux flame, the stability of comparatively effectual promotion burning, under the heavy load condition, optimize the injection strategy of fuel, comparatively effectual prevention burning is too rough.

The embodiments of the present disclosure have been described above. However, these examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Although the embodiments are described separately above, this does not mean that the measures in the embodiments cannot be used in advantageous combination. The scope of the disclosure is defined by the appended claims and equivalents thereof. Various alternatives and modifications can be devised by those skilled in the art without departing from the scope of the present disclosure, and such alternatives and modifications are intended to be within the scope of the present disclosure.

Claims

1. A combustion system, comprising:

a body (2);

a piston (1) mounted within the body (2);

a cylinder head (3) mounted in an open position of the body (2), the cylinder head (3), the body (2) and the piston (1) defining a first combustion chamber (4);

the first combustion part is arranged in the middle of the cylinder cover (3), is communicated with the first combustion chamber (4) and is used for injecting fuel into the first combustion chamber (4); and

a second combustion unit provided in the cylinder head (3) at a position beside the first combustion unit and communicating with the first combustion chamber (4), the second combustion unit including:

a second combustion chamber (8) formed in the cylinder head (3), the fuel of the second combustion chamber (8) being combusted prior to the fuel of the first combustion chamber (4); and

and the jet hole (11) is formed on the surface of the cylinder cover (3) opposite to the piston (1) and is used for forming the jet flame by the fuel combusted in the second combustion chamber (8) so as to ignite the fuel beam formed by the fuel in the first combustion chamber (4) and enable the fuel beam in the first combustion chamber (4) to be combusted in a diffusion combustion mode.

2. The combustion system of claim 1, further comprising:

an intake duct (12) formed in the cylinder head (3); and

an exhaust passage (15) formed on the other radial side of the cylinder head (3) that is symmetrical to the intake passage (12);

wherein an inlet valve (13) is mounted in the air inlet channel (12) in an openable and closable manner; an exhaust valve (14) is mounted in the exhaust passage (15) in an openable and closable manner.

3. The combustion system according to claim 2, wherein a line connecting the first and second combustion portions formed in a radial plane of the cylinder head (3) is perpendicular to a line connecting the intake passage (12) and the exhaust passage (15).

4. A combustion system according to any one of claims 1-3, wherein said first combustion portion comprises a first fuel injector (6) arranged in a central position of said cylinder head (3) and extending into said first combustion chamber (4) in an axial direction of said cylinder head (3); and a first axial end of the first fuel injector (6) in the first combustion chamber (4) is provided with a spray hole along the circumferential direction.

5. The combustion system according to claim 4, wherein a surface of the piston (1) facing the cylinder head (3) is formed with a groove, the surface of the groove is smoothly provided, and fuel injected from the injection hole of the first fuel injector (6) forms a vortex cluster through the surface of the groove.

6. The combustion system of any of claims 1-3, wherein the second combustion section further comprises:

a second injector (10) provided in the second combustion chamber (8) for injecting fuel into the second combustion chamber (8); and

and an ignition plug (9) provided in the second combustion chamber (8) to ignite the fuel injected by the second injector (10).

7. An engine, comprising:

the combustion system of any one of claims 1 to 6;

a monitoring unit adapted to monitor the position of the piston (1); and

a control unit adapted to control the ignition timing of the second combustion section in accordance with the position of the piston (1);

wherein the second combustion part comprises a second injector (10) and a spark plug (9).

8. A combustion control method of an engine, comprising:

monitoring the position of a piston (1) of an engine; and

and controlling the ignition timing of the spark plug (9) according to the position of the piston (1).

9. The control method according to claim 8, wherein monitoring the position of the piston (1) of the engine comprises obtaining the position of the piston (1) from an angle of a crank angle of a crankshaft linked with the piston (1) in one working cycle of the piston.

10. A control method according to claim 9, wherein controlling the ignition timing of the spark plug (9) in accordance with the position of the piston (1) comprises injecting fuel by the second injector (10) during the time when the piston (1) is again near top dead center in one working cycle of the piston, after which the spark plug (9) ignites, and controlling the first injector (6) to inject fuel into the first combustion chamber (4) based on the ignition timing of the spark plug (9) for achieving ignition of the fuel injected by the first injector (6) by the jet flame.