A variable compression ratio compression ignition engine jet combustion system

Abstract

The application provides a variable compression ratio compression ignition engine jet combustion system, which comprises an engine combustion system and a variable compression ratio jet structure arranged near an exhaust passage; the variable compression ratio jet structure comprises a variable cavity, a steam port, a jet passage and a jet port which are sequentially connected in communication, the steam port is arranged above the variable cavity in the direction opposite to gravity, an edge oil injector is further arranged above the variable cavity, the edge oil injector and a middle oil injector share a fuel supply system, and the jet passage is communicated with a combustion chamber through the jet port. The application is modified on the basis of an existing compression ignition engine cylinder head, the edge oil injector above the variable cavity is added in the exhaust passage, the jet passage is added between the variable cavity and the existing combustion chamber, the edge oil injector is controlled in the starting condition, and high compression ratio is adopted; in the large load, external characteristic or rated condition, low compression ratio is adopted. Through the oil injection strategy of the edge oil injector and the middle oil injector, variable compression ratio jet combustion of the compression ignition engine in different conditions is realized.

Description

Technical Field

[0001] This invention belongs to the field of high-power special engines, and in particular relates to a variable compression ratio compression ignition engine jet combustion system. Background Technology

[0002] For reciprocating piston internal combustion engines, given a certain level of engine mechanical strength, it is difficult to simultaneously improve both power and fuel economy to extremely high levels. In compression ignition engine designs where power is the primary performance indicator, fuel economy and cold start capability are often poor. Variable compression ratio technology can better balance fuel economy and operating condition adaptability while ensuring power, and has been successfully applied in passenger car engines, but is less commonly used in commercial vehicle compression ignition engines or special-purpose engines. Jet combustion technology can shorten the combustion duration to a certain extent, and has the potential to expand compression ignition engines towards higher power and fuel economy. This invention aims to propose a variable compression ratio compression ignition engine jet combustion system. Summary of the Invention

[0003] In view of this, the present invention aims to propose a variable compression ratio compression ignition engine jet combustion system. Based on the existing compression ignition engine cylinder head, it modifies the system by adding a variable chamber and a side injector above the variable chamber in the exhaust manifold, and adding a jet channel between the variable chamber and the existing combustion chamber. During startup, the side injector is controlled to employ a high compression ratio; under high load, external characteristic, or calibration conditions, a low compression ratio is employed. By controlling the injection strategies of the side and center injectors, jet combustion of the compression ignition engine under different operating conditions can be achieved.

[0004] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0005] A variable compression ratio compression ignition engine jet combustion system includes an engine combustion system and a variable compression ratio jet structure disposed in an exhaust manifold.

[0006] The variable compression ratio jet structure includes a variable cavity, a steam port, a jet channel, and a jet outlet connected in sequence. The steam port is located above the variable cavity in the opposite direction of gravity. A side injector is also provided above the variable cavity.

[0007] The side injectors and center injectors share a fuel supply system, but employ different injection strategies;

[0008] The jet channel is connected to the combustion chamber through the jet port.

[0009] Furthermore, the diameter of the jet nozzle ranges from 3mm to 20mm, and the angle between the direction of the working fluid flowing out of the jet nozzle and the vertical direction ranges from 1° to 89°.

[0010] Furthermore, variable compression ratio jet structures are used in compression ignition and spark-ignition engines that burn liquid fuels.

[0011] First, a variable chamber is created in the exhaust manifold. The volume of the variable chamber affects the range of the variable compression ratio. The existing engine has a single-cylinder combustion chamber volume V0, a ​​single-cylinder displacement V1, an injection channel volume V2, and a variable chamber volume V3 at top dead center. The compression ratio Cr of the modified engine is calculated using formula (1). Changing the value of V3 can change the geometric compression ratio of the engine.

[0012]

[0013] The change in geometric compression ratio is achieved by installing a side injector above the variable cylinder, which uses the same fuel supply system as the center injector. When the engine is in startup mode, the overall engine temperature is low, and the side injector is controlled to inject fuel, filling the variable cylinder. At this time, the compression ratio increases, which is beneficial to improving the probability of compression ignition and shortening the start-up time. As the engine load increases, the exhaust port temperature rises, and the fuel in the variable cylinder vaporizes and enters the injection channel through the vapor port. It mixes and burns with the air in the injection channel. The temperature and pressure of the working fluid in the injection channel increase, which injects the high-temperature and high-pressure mixture and some combustion intermediate products into the cylinder, increasing the in-cylinder turbulent kinetic energy and promoting in-cylinder fuel-air mixing, thus accelerating the overall combustion reaction rate. Under heavy load or calibration conditions, the exhaust port temperature often reaches a very high level, far exceeding the fuel final distillation temperature. The fuel injected by the side injector will quickly vaporize, leaving almost no incompressible liquid state, thus affecting the volume of the variable chamber. This is the state of minimum compression ratio. By flexibly controlling the injection strategies of the side injector and the center injector, the energy of the working fluid ejected from the jet and the overall combustion reaction rate can be regulated, thereby matching the engine operating boundary and mechanical boundary.

[0014] Compared with existing technologies, the variable compression ratio compression ignition engine jet combustion system described in this invention has the following advantages:

[0015] (1) The variable compression ratio compression ignition engine jet combustion system described in this invention can achieve engine combustion rate control and variable compression ratio adjustment through the injection strategy of two injectors, and the technology is highly mature.

[0016] (2) The variable compression ratio compression ignition engine jet combustion system of the present invention can adjust the compression ratio according to the operating conditions, thereby improving the engine's power, operating condition adaptability and fuel economy under partial load.

[0017] (3) The variable compression ratio compression ignition engine jet combustion system of the present invention has a jet channel and variable cavity that increase the surface volume ratio of the engine combustion chamber, which may increase the risk of heat loss. Attached Figure Description

[0018] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0019] Figure 1 This is a top view schematic diagram of a variable compression ratio compression ignition engine jet combustion system according to an embodiment of the present invention;

[0020] Figure 2 This is a half-sectional schematic diagram of a variable compression ratio compression ignition engine jet combustion system according to an embodiment of the present invention.

[0021] Explanation of reference numerals in the attached figures:

[0022] 1. Exhaust passage; 2. Exhaust valve; 3. Intake valve; 4. Injector mounting hole; 5. Variable compression ratio jet structure; 6. Cooling water chamber; 7. Side injector; 8. Steam port; 9. Injector; 10. Combustion chamber; 11. Injector port; 12. Cylinder liner; 13. Injector passage; 14. Variable cavity. Detailed Implementation

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0024] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0025] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0026] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0027] A variable compression ratio compression ignition engine jet combustion system is described, in conjunction with a four-valve structure, such as... Figures 1 to 2 As shown,

[0028] Based on the existing technology, it is necessary to modify the structure near the cylinder head exhaust port to add a variable compression ratio jet structure 5; the variable compression ratio jet structure 5 includes a variable cavity 14, a steam port 8, a jet channel 13, and a jet port 11, which are connected in sequence, wherein the steam port 8 is located above the variable cavity 14 in the opposite direction of gravity.

[0029] The existing engine has a single-cylinder combustion chamber volume V0, a ​​single-cylinder displacement V1, a jet channel volume V2, and a variable cavity volume V3 at top dead center. The compression ratio Cr of the modified engine is calculated using formula (1). Changing the value of V3 can change the geometric compression ratio of the engine.

[0030]

[0031] A side injector 7 is installed above the variable cavity 14, and the side injector 7 and the center injector 9 share a fuel supply system.

[0032] The volume of the variable cavity 14 does not include the portion above the lower end face of the steam port 8. The volume of the variable cavity can determine the variable range of the compression ratio. The variable cavity 14 has an appropriate proportion of its outer surface in the exhaust duct 1.

[0033] The jet channel 13 is connected to the combustion chamber 10 through the jet port 11. The average velocity direction of the working fluid flowing out of the jet port 11 is within the range of 1°-89° with the vertical direction. The diameter of the jet port 11 is within the range of 3mm-20mm.

[0034] When the engine starts, the side injector 7 injects fuel, filling the variable chamber 14 to near the steam port 8. At this time, the engine's compression ratio increases, which helps to improve the in-cylinder thermal atmosphere and increase the ignition probability. The fuel for combustion in the cylinder is supplied by the central injector 9, and the combustion control method is the same as that of existing compression ignition engines.

[0035] After the engine starts, the temperature in the exhaust manifold 1 begins to rise, and the fuel in the variable chamber 14 begins to absorb heat and vaporize, mixing with the fresh air entering the injection passage 13 during the compression stroke. When the hot atmosphere reaches the ignition conditions, combustion begins, heating and pressurizing the mixture in the injection passage. The working fluid in the injection passage enters the combustion chamber 10 through the injection port 11. Because the ejected working fluid has a high velocity, it can increase the turbulent kinetic energy in the cylinder. Since the ignition process can only approach the top dead center at low loads, the injection timing largely coincides with the injection process of the intermediate injector 9, which to some extent promotes mixing and increases the combustion rate. In this process, the fuel burned in the cylinder consists of the vaporized fuel in the variable chamber 14 and the fuel injected by the intermediate injector 9, and the compression ratio gradually decreases.

[0036] When under heavy load, the exhaust temperature rises further, far exceeding the final distillation temperature of the fuel. The fuel in the variable chamber 14 is essentially vaporized, and the compression ratio has decreased to its minimum. At this point, a suitable injection timing can be selected within the range from near exhaust valve closing to before top dead center, controlling the circulating fuel quantity of the side injector 7. When the fuel is injected by the central injector 9 and combustion begins in the cylinder, the fuel in the variable chamber 14 vaporizes and ignites, pushing the working fluid in the jet chamber into the cylinder, thus promoting in-cylinder fuel-air mixing and increasing the combustion rate. To obtain higher power output, the compression ratio in this process can be lower than the minimum compression ratio of existing compression-ignition engines, thus possessing the potential to increase maximum output power.

[0037] This embodiment takes a four-valve compression ignition engine as an example, but is not limited to compression ignition engines. The variable compression ratio jet structure 5 can also be applied to non-four-valve engines and spark-ignition engines.

[0038] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for operating a jet combustion system in a variable compression ratio compression ignition engine, characterized in that: The combustion system includes the engine combustion system and a variable compression ratio jet structure located near the exhaust port; The variable compression ratio jet structure includes a variable cavity, a steam port, a jet channel, and a jet outlet connected in sequence. The steam port is located above the variable cavity in the opposite direction of gravity, and a side injector is also provided above the variable cavity. The side injectors and center injectors share a fuel supply system, but employ different injection strategies; The jet channel is connected to the combustion chamber through the jet nozzle; Combustion system operation method: When the engine starts, the side injectors inject fuel to fill the variable chamber to the vicinity of the steam port. At this time, the compression ratio of the engine increases, which can improve the hot atmosphere in the cylinder and increase the ignition probability. The fuel for combustion in the cylinder is supplied by the central injectors, and the combustion control method is the same as the existing compression ignition engine control method. Once the engine has started, the temperature in the exhaust manifold begins to rise. The fuel in the variable cylinder chamber begins to absorb heat and vaporize, mixing with the fresh air entering the injection channel during the compression stroke. When the hot atmosphere reaches the ignition conditions, combustion begins, heating and pressurizing the mixture in the injection channel. The working fluid in the injection channel enters the combustion chamber through the injection port. Because the ejected working fluid has a high velocity, it increases the turbulent kinetic energy in the cylinder. Since the ignition process is near top dead center at lower loads, the injection timing largely coincides with the injection process of the intermediate injector, achieving the purpose of promoting mixing and increasing the combustion rate. During this process, the fuel burned in the cylinder consists of vaporized fuel in the variable cylinder chamber and fuel injected from the intermediate injector, and the compression ratio gradually decreases. When under heavy load, the exhaust temperature rises further, far exceeding the final distillation temperature of the fuel. The fuel in the variable combustion chamber is completely vaporized, and the compression ratio drops to its minimum. At this point, the injection timing can be selected within the range from near the exhaust valve closing time to before top dead center, controlling the circulating fuel quantity of the side injectors. When the fuel is injected by the central injector and combustion begins in the cylinder, the fuel in the variable combustion chamber is vaporized and ignited, pushing the working fluid in the jet chamber into the cylinder, thereby promoting in-cylinder fuel-air mixing and increasing the combustion rate. To obtain higher power output, the compression ratio in this process can be lower than the minimum compression ratio of existing compression ignition engines, possessing the potential to increase the maximum output power.

2. The operating method of a variable compression ratio compression ignition engine jet combustion system according to claim 1, characterized in that: The diameter of the jet nozzle ranges from 3mm to 20mm, and the angle between the direction of the average velocity of the working fluid flowing out of the jet nozzle and the vertical direction ranges from 1° to 89°.

3. The operating method of a variable compression ratio compression ignition engine jet combustion system according to claim 1, characterized in that: Variable compression ratio jet structures are used in compression ignition and spark ignition engines that burn liquid fuels.

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