CN110821664A - Dual-fuel ignition chamber type four-stroke engine and combustion control method - Google Patents

Abstract

The present invention provides a dual-fuel ignition chamber type four-stroke engine and a combustion control method, which belongs to the field of internal combustion engine combustion. A first fuel nozzle is arranged on the cylinder head and/or on the intake passage, a second fuel nozzle is arranged on the cylinder head and/or on the intake passage, an ignition chamber is arranged on the cylinder head, and an ignition chamber second fuel nozzle and a spark plug are arranged on the ignition chamber. The ignition chamber is connected to the combustion chamber by a channel, and after the spark plug ignites the mixed gas in the ignition chamber, the engine is triggered to ignite in the form of a flame jet. When the main fuel nozzle is installed on the cylinder head and the intake passage at the same time, at low load, the main fuel nozzle for direct injection in the cylinder is used to supply fuel to improve thermal efficiency; at medium load, the main fuel nozzle for the intake passage supplies fuel to reduce the generation of NOx; at high load, the main fuel nozzle for the intake passage and the main fuel nozzle for direct injection in the cylinder both supply fuel to control knock. Efficient and clean combustion is achieved in the full range of working conditions, and the energy structure is optimized.

Description

A dual-fuel ignition chamber type four-stroke engine and combustion control method

technical field

The invention relates to a dual-fuel ignition chamber type four-stroke engine and a combustion control method, belonging to the field of combustion of internal combustion engines.

Background technique

In order to reduce emissions, efforts are currently being made to improve the leanness of the mixture in the engine cylinder, and the ignition effect of the spark plug is not good, especially as the cylinder diameter increases, the ignition effect of the spark plug is even worse. There are problems with cold start difficulties and high HC and CO emissions under low load conditions.

Energy and environmental issues are becoming more and more prominent. Low temperature combustion of premixed compression ignition can improve the thermal efficiency of the engine and reduce NOx emissions. However, the ignition timing of premixed compression ignition is affected by environmental conditions and engine operating conditions, and it is difficult to control reliably. In addition, its working condition range is small, cold start and low load will produce excessive HC and CO, and high load will produce knocking.

It is difficult for a single-fuel engine to meet the needs of energy diversification, and the combustion characteristics of a single fuel have limitations, which limit the performance improvement of the engine.

SUMMARY OF THE INVENTION

The invention discloses a dual-fuel ignition chamber type four-stroke engine and a combustion control method. By setting the ignition chamber, two main fuel intake port nozzles and in-cylinder direct injection nozzles, and adjusting the injection strategy, the ignition chamber type four-stroke engine can achieve efficient and clean combustion within the full range of operating conditions, and optimize the energy structure.

The technical scheme adopted in the present invention is: a dual-fuel ignition chamber type four-stroke engine, comprising an intake port, an exhaust port and a combustion chamber, a first fuel nozzle for direct injection in the cylinder is arranged on the cylinder head and/or a first fuel nozzle for direct injection in the cylinder is arranged on the cylinder head The first fuel nozzle of the intake port is arranged on the intake port, the second fuel nozzle of the direct injection in the cylinder is arranged on the cylinder head and/or the second fuel nozzle of the intake port is arranged on the intake port; the ignition chamber is arranged on the cylinder head A second fuel nozzle and a spark plug of the ignition chamber are arranged on the ignition chamber, and the ignition chamber is connected with the combustion chamber by a channel. The ignition method of the engine is that the spark plug ignites the mixture in the ignition chamber, and the flame jet rich in active radicals is injected into the combustion chamber from the channel to trigger the combustion of fuel in the cylinder.

Further, the structure of the ignition chamber is designed according to the arrangement of the cylinder head, the volume of the ignition chamber is not greater than 5% of the clearance volume; the number of channels between the ignition chamber and the combustion chamber is at least one, and the cross-section of the channel is a circle. The shape or inlet is circular, the outlet is narrow slot, ellipse, rounded rectangle with smaller area, and the longitudinal section of the channel adopts straight cylinder, tapered, tapered, tapered or tapered tapered or a combination of the above shapes.

Further, the ignition chamber is located in the center of the cylinder head, the in-cylinder direct injection main fuel nozzle is arranged on the side, and the number of in-cylinder direct injection main fuel nozzles is at least one; or the in-cylinder direct injection main fuel nozzle is Located in the center of the cylinder head, the ignition chamber is arranged on the side, and the number of the ignition chamber is at least one.

Further, the ignition chamber, the bottom of the cylinder head, the bottom of the gas valve, the top surface of the piston and the fire power land, and the upper part of the cylinder liner that are not in contact with the piston ring are sprayed with a thermal insulation coating and/or the ignition chamber, the top of the piston is selected from thermal insulation materials, and/or An electric heating device is provided on the ignition chamber.

Further, variable valve technology is employed and/or exhaust gas recirculation technology is employed.

Further, when the main fuel is diesel, ethers, or mixed fuel containing diesel, or mixed fuel containing ethers, the fuel nozzle can only select the main fuel nozzle for direct injection in the cylinder, and the compression ratio is set to the main fuel and cannot be directly injected. The critical compression ratio for compression ignition, premixed compression ignition is performed.

A combustion control method for a dual-fuel ignition chamber type four-stroke engine, the engine is provided with a main fuel nozzle that is easily atomized on a cylinder head and an intake port at the same time, and the compression ratio is set to a critical compression where the main fuel cannot be directly compressed and ignited Compared with the premixed compression ignition method, the ignition chamber flame jet ignition is used. Or, according to the size of the working conditions, the following controls are performed:

When the load is low, use the direct injection main fuel nozzle in the cylinder to supply fuel;

At medium load, the main fuel nozzle of the intake port is used to supply fuel;

At high loads, the port main fuel nozzle and the in-cylinder direct injection main fuel nozzle are used to supply fuel.

During a cold start, the variable valve technology is used to increase the compression ratio and/or the ignition chamber is preheated by an electric heating device, and the main fuel is injected into the ignition chamber for ignition.

The second main fuel nozzle of the ignition chamber can be injected multiple times. During the early injection, the pressure of the second main fuel injected in the ignition chamber is greater than the pressure in the combustion chamber. The second main fuel enters the cylinder through the channel of the ignition chamber, and the second main fuel injected in the later stage Left in the ignition chamber; the fuel in the ignition chamber consists of two parts, one part is the fuel pressed into the ignition chamber by the combustion chamber through the passage, and the other part is the fuel injected by the second main fuel nozzle of the ignition chamber.

The beneficial effects of the invention are that the flame jet of the ignition chamber of the dual-fuel ignition chamber type four-stroke engine can control the ignition phase of the premixed compression ignition, which can further improve the ignition performance and burn quickly. When the engine is equipped with main fuel nozzles that are easily atomized at the same time on the cylinder head and the intake port, the injection strategy of different working conditions is carried out under different working conditions to realize different combustion modes. It is also possible to set a critical compression ratio and use ignition. Premixed compression ignition with chamber flame jet ignition. In this way, efficient and clean combustion in all operating conditions is achieved, and the energy structure is optimized.

Description of drawings

In order to illustrate the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are some embodiments of the present invention, and for those of ordinary skill in the art, other drawings can also be obtained from these drawings without any creative effort.

FIG. 1 is a structural diagram of a dual-fuel ignition chamber type four-stroke engine.

In the figure: 1. Intake port, 2. Exhaust port, 3. Combustion chamber, 4. First fuel nozzle in intake port, 5. Second fuel nozzle in intake port, 6. First fuel nozzle with direct injection in cylinder , 7, the second fuel nozzle of direct injection in the cylinder, 8, the ignition chamber, 9, the second fuel nozzle of the ignition chamber, 10, the spark plug.

Detailed ways

It should be noted that the embodiments of the present invention and the features of the embodiments may be combined with each other under the condition of no conflict. The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments It is only a part of the embodiments of the present invention, but not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

It should be noted that the terminology used herein is for the purpose of describing specific embodiments only, and is not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural as well, furthermore, it is to be understood that when the terms "comprising" and/or "including" are used in this specification, it indicates that There are features, steps, operations, devices, components and/or combinations thereof.

The relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the invention unless specifically stated otherwise. Meanwhile, it should be understood that, for convenience of description, the dimensions of various parts shown in the accompanying drawings are not drawn in an actual proportional relationship. Techniques, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the authorized specification. In all examples shown and discussed herein, any specific value should be construed as illustrative only and not as limiting. Accordingly, other examples of exemplary embodiments may have different values. It should be noted that like numerals and letters refer to like items in the following figures, so once an item is defined in one figure, it does not require further discussion in subsequent figures.

In the description of the present invention, it should be understood that the orientations indicated by orientation words such as "front, rear, top, bottom, left, right", "horizontal, vertical, vertical, horizontal" and "top, bottom" etc. Or the positional relationship is usually based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, and these orientation words do not indicate or imply the indicated device or element unless otherwise stated. It must have a specific orientation or be constructed and operated in a specific orientation, so it should not be construed as a limitation on the scope of protection of the present invention: the orientation words "inside and outside" refer to the inside and outside relative to the contour of each component itself.

For ease of description, spatially relative terms, such as "on", "over", "on the surface", "above", etc., may be used herein to describe what is shown in the figures. The spatial positional relationship of one device or feature shown to other devices or features. It should be understood that spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "above" or "over" other devices or features would then be oriented "below" or "over" the other devices or features under its device or structure". Thus, the exemplary term "above" can encompass both an orientation of "above" and "below." The device may also be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptions used herein interpreted accordingly.

In addition, it should be noted that the use of words such as "first" and "second" to define components is only for the convenience of distinguishing corresponding components. Unless otherwise stated, the above words have no special meaning and therefore cannot be understood to limit the scope of protection of the present invention.

In order to further understand the content of the invention of the present invention, the present invention is described in detail as follows in conjunction with the accompanying drawings:

Example 1:

As shown in FIG. 1 , the engine includes an intake port 1 , an exhaust port 2 and a combustion chamber 3 , and a first fuel nozzle 6 for direct injection in the cylinder is provided on the cylinder head and/or an inlet port 1 is provided on the intake port 1 . The first fuel nozzle 4 in the port, the second fuel nozzle 7 for direct injection in the cylinder is set on the cylinder head and/or the second fuel nozzle 5 in the intake port is set on the intake port 1; the ignition chamber is set on the cylinder head 8. The ignition chamber 8 is provided with a second ignition chamber fuel nozzle 9 and a spark plug 10, and the ignition chamber 8 is connected with the combustion chamber 3 by a channel. The ignition mode of the engine is that the spark plug 10 ignites the mixture in the ignition chamber 8, and the flame jet rich in active radicals is injected into the combustion chamber 3 from the channel to trigger the combustion of the fuel in the cylinder.

The structure of the ignition chamber 8 is designed according to the arrangement of the cylinder head, the volume of the ignition chamber 8 is not greater than 5% of the clearance volume; the number of channels between the ignition chamber 8 and the combustion chamber 3 is at least one, and the channel cross section is The entrance is circular or the entrance is circular, and the exit is narrow slot, oval, rounded rectangle with smaller area, and the longitudinal section of the channel adopts straight cylinder, tapered, tapered, tapered and tapered tapered or tapered tapered shape or a combination of the above shapes.

The ignition chamber 8 is located in the center of the cylinder head, the in-cylinder direct injection main fuel nozzle is arranged on the side, and the number of in-cylinder direct injection main fuel nozzles is at least one; or the in-cylinder direct injection main fuel nozzle is located in the cylinder. In the center of the cover, the ignition chamber 8 is arranged on the side, and the number of the ignition chamber 8 is at least one.

The ignition chamber 8, the bottom of the cylinder head, the bottom of the valve, the top surface of the piston and the fire land, and the upper part of the cylinder liner that are not in contact with the piston ring are sprayed with thermal insulation coating and/or the ignition chamber, and the top of the piston is selected with thermal insulation material to reduce heat transfer loss , to further improve the thermal efficiency of the engine, and/or to set an electric heating device on the ignition chamber 8 to achieve stable ignition during cold start, or to achieve ignition under conditions that exceed the normal combustion limit, and to speed up the combustion rate in the ignition chamber 8, Increases flamethrower energy. .

Adopt variable valve technology to achieve variable compression ratio.

Exhaust gas recirculation technology is used to control the combustion rate of fuel in the cylinder.

When the main fuel is diesel, ether, or mixed fuel containing diesel, or mixed fuel containing ether, the fuel nozzle can only choose the main fuel nozzle of direct injection in the cylinder, and the compression ratio is set to the main fuel that cannot be directly compressed. Critical compression ratio, premixed compression ignition.

A combustion control method for a dual-fuel ignition chamber type four-stroke engine, the engine is provided with a main fuel nozzle that is easily atomized on a cylinder head and an intake port at the same time, and the compression ratio is set to a critical compression where the main fuel cannot be directly compressed and ignited Compared with the premixed compression ignition method, the ignition chamber flame jet ignition is used. Or, according to the size of the working conditions, the following controls are performed:

When the load is low, the direct injection main fuel nozzle in the cylinder is used to supply fuel to form a stratified mixture in the cylinder to achieve sufficient and rapid combustion and reduce HC and CO emissions.

At medium load, the main fuel nozzle of the intake port is used to supply fuel to form a relatively homogeneous lean mixture in the cylinder to achieve rapid combustion and reduce NOx emissions.

When the load is high, the main fuel nozzle of the intake port and the main fuel nozzle of direct injection in the cylinder are used to supply fuel to form a relatively homogeneous pre-mixture in the cylinder, and the main fuel nozzle of direct injection in the cylinder is supplemented near the compression top dead center. fuel, suppress knocking, and achieve stable, efficient and clean combustion.

During cold start, the variable valve technology is used to increase the compression ratio, so that the mixture in the ignition chamber is easier to ignite, and/or the ignition chamber 8 is preheated by the electric heating device on the ignition chamber 8, and the main fuel is injected into the ignition chamber 8 for ignition .

The second fuel nozzle 9 in the ignition chamber can be injected multiple times. During the early injection, the pressure of the second fuel injected in the ignition chamber is greater than the pressure in the combustion chamber, and the second fuel enters the cylinder through the channel of the ignition chamber; the second fuel injected at the later stage remains in the ignition chamber. Room 8.

The fuel in the ignition chamber 8 consists of two parts, one part is the fuel pressed into the ignition chamber by the combustion chamber through the passage, and the other part is the fuel injected by the second fuel nozzle 9 of the ignition chamber.

In this example, taking methanol and natural gas as the main fuels as an example, a four-stroke engine is used for research. Compared with the original engine, the thermal efficiency is increased by 10%, nitrogen oxides are reduced by 70%, particulate matter emissions are reduced by 95%, and carbon dioxide emissions are reduced by 95%. Hydrogen emissions are reduced by 45% and carbon monoxide emissions are reduced by 40%. Other embodiments of the present invention can also achieve the effect of efficient and clean combustion.

Example 2: The difference from Example 1 is that the first fuel nozzle 4 in the intake port is reduced, and the first fuel nozzle 6 with direct injection in the cylinder, the second fuel nozzle 7 with direct injection in the cylinder and the second fuel nozzle in the intake port are used. 5Inject the main fuel to achieve efficient and clean combustion.

Example 3: The difference from Example 1 is that the first fuel nozzle 6 for direct injection in the cylinder is reduced, the first fuel nozzle 4 for the intake port, the second main fuel nozzle 5 for the intake port and the second fuel for direct injection in the cylinder are reduced. Nozzle 7 injects main fuel to achieve efficient and clean combustion.

Example 4: The difference from Example 1 is that the intake port first fuel nozzle 4 and the in-cylinder direct injection second fuel nozzle 7 are reduced, and the intake port second fuel nozzle 5 and the in-cylinder direct injection first fuel nozzle are 6. Main fuel is injected to achieve efficient and clean combustion.

Example 5: Different from Examples 1-4, by using variable valve technology and exhaust gas recirculation technology, a critical compression ratio is set, so that the mixture is in a critical state that cannot be directly compressed and ignited but is close to being compressed. , using the premixed compression ignition method with flame jet ignition in the ignition chamber for efficient and clean combustion.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features thereof can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention. scope.

Claims (9)

1. A dual-fuel ignition chamber type four-stroke engine comprises an air inlet channel (1), an air outlet channel (2) and a combustion chamber (3), and is characterized in that a cylinder cover is provided with a first fuel nozzle (6) for direct injection in a cylinder and/or the air inlet channel (1) is provided with a first fuel nozzle (4) for the air inlet channel, the cylinder cover is provided with a second fuel nozzle (7) for direct injection in the cylinder and/or the air inlet channel (1) is provided with a second fuel nozzle (5); an ignition chamber (8) is arranged on the cylinder cover, a second fuel nozzle (9) of the ignition chamber and a spark plug (10) are arranged on the ignition chamber (8), and the ignition chamber (8) is connected with the combustion chamber (3) through a channel; the ignition mode of the engine is that a spark plug (10) ignites the mixed gas in an ignition chamber (8), and flame jet flow rich in active groups is sprayed into a combustion chamber (3) from a channel to trigger the combustion of fuel in a cylinder.

2. A dual fuel firing chamber four stroke engine as claimed in claim 1 wherein: the structure of the ignition chamber (8) is designed according to the arrangement condition of a cylinder cover, and the volume of the ignition chamber (8) is not more than 5% of the clearance volume; the number of the channels of the ignition chamber (8) and the combustion chamber (3) is at least 1, the cross section of the channel is circular or the inlet is circular, the outlet is in the shape of a narrow slit with a small area, an ellipse or a rounded rectangle, and the longitudinal section of the channel adopts a straight cylinder shape, a tapered shape, a gradually expanded shape or a gradually contracted and gradually expanded shape or the combination of the shapes.

3. A dual fuel firing chamber four stroke engine as claimed in claim 1 wherein: the ignition chamber (8) is positioned in the center of the cylinder cover, the in-cylinder direct injection main fuel nozzles are arranged on the side surface, and the number of the in-cylinder direct injection main fuel nozzles is at least 1; or the direct injection main fuel nozzle is positioned in the center of the cylinder cover, the ignition chambers (8) are arranged on the side surface, and the number of the ignition chambers (8) is at least 1.

4. A dual fuel firing chamber four stroke engine as claimed in claim 1 wherein: the ignition chamber (8), the bottom of the cylinder cover, the bottom of the air valve, the top surface of the piston, the fire bank and the upper part of the cylinder sleeve which can not be contacted by the piston ring are sprayed with a heat insulation coating and/or the ignition chamber (8), and the top of the piston is selected from a heat insulation material; and/or an electric heating device is arranged on the ignition chamber (8).

5. A dual fuel firing chamber four stroke engine as claimed in claim 1 wherein: using variable valve technology and/or using exhaust gas recirculation technology.

6. A dual fuel firing chamber four stroke engine as claimed in claim 1 wherein: when the main fuel is diesel oil, ether, or mixed fuel containing diesel oil or mixed fuel containing ether, the fuel nozzle can only select the in-cylinder direct injection main fuel nozzle, the compression ratio is set to the critical compression ratio that the main fuel can not be directly compressed to ignite, and the premixed compression ignition is carried out.

7. A combustion control method of a dual-fuel ignition chamber type four-stroke engine is characterized in that:

the engine is provided with a main fuel nozzle which is easy to atomize on a cylinder cover and an air inlet channel simultaneously, the compression ratio is set to be a critical compression ratio at which the main fuel can not be directly compressed and ignited, and a premixed compression ignition mode of flame jet ignition of an ignition chamber is adopted; or, the following control is carried out according to the working condition size:

at low load, fuel is supplied by using a direct injection main fuel nozzle in the cylinder;

at medium load, fuel is supplied by using a main fuel nozzle of an air inlet;

at high load, fuel is supplied using the intake port main fuel nozzle and the in-cylinder direct injection main fuel nozzle.

8. The combustion control method of a dual-fuel firing chamber type four-stroke engine according to claim 7, characterized in that: during cold starting, the variable valve technology is adopted to improve the compression ratio and/or an electric heating device is used for preheating the ignition chamber (8), and main fuel is injected into the ignition chamber (8) for ignition.

9. The combustion control method of a dual-fuel firing chamber type four-stroke engine according to claim 7, characterized in that: the second main fuel nozzle (9) of the ignition chamber can be used for injecting for multiple times, during early injection, the pressure of the second main fuel injected into the ignition chamber is greater than the pressure in the combustion chamber (3), the second main fuel enters the cylinder through a channel of the ignition chamber (8), and the second main fuel injected later is left in the ignition chamber (8); the fuel in the ignition chamber (8) consists of two parts, one part is the fuel pressed into the ignition chamber (8) by the combustion chamber (3) through a channel, and the other part is the fuel sprayed by the second main fuel nozzle (9) of the ignition chamber.

Images