A two-stage combustion multi-stroke cycle system and method with controllable intake and exhaust valves

Abstract

A two-stage combustion multi-stroke circulation system and method with controllable intake and exhaust valves, which relates to a two-stage combustion multi-stroke circulation system and method. The present invention aims to solve the problem that existing engines generate a large amount of excess heat energy, which not only needs to be dissipated through the engine cylinder wall, but is also discharged as wasted energy during the cycle exhaust stroke. The circulation system of the present invention includes a cylinder assembly, an intake structure, an exhaust structure and an air storage structure; the intake structure is connected to the air intake port of the cylinder assembly, and the exhaust port of the cylinder assembly is connected to the air storage structure through the exhaust structure. The present invention belongs to the field of internal combustion engine combustion technology.

Description

Technical Field

[0001] The invention relates to a two-stage combustion multi-stroke cycle system and method, belonging to the technical field of internal combustion engine combustion. Background Art

[0002] Due to the excessive use and exploitation of petroleum energy, China and even the world are facing a serious energy crisis, and the world's oil reserves are also decreasing significantly. At the same time, given that the utilization rate of these petroleum energy in existing internal combustion engines is not high (low thermal efficiency), it causes high fuel consumption and high emissions, as well as high exhaust noise, causing serious pollution and harm to the atmosphere and the environment. The current internal combustion engine completes external work and outputs power through four strokes of intake, compression, explosion, and exhaust as a working cycle (gasoline engines are spark ignition type and diesel engines are compression ignition type). Only the explosion stroke is the power stroke, and the other three are auxiliary strokes, which do not do external work. Even the most efficient modern four-stroke engine has the main disadvantage of generating a large amount of excess heat energy, which is dissipated through the cylinder wall of the engine and discharged as wasted energy in the exhaust stroke of the cycle.

[0003] Therefore, how to effectively utilize the heat energy generated by fuel combustion, effectively improve the thermal efficiency of the engine, increase the power density, improve the overall performance of the engine and improve the economy of the engine is a problem that needs to be solved urgently. Summary of the invention

[0004] The present invention aims to solve the problem that existing engines generate a large amount of excess heat energy, which not only needs to be dissipated through the engine cylinder wall, but is also discharged as wasted energy in the cycle exhaust stroke. A two-stage combustion multi-stroke cycle system and method with controllable intake and exhaust valves is proposed.

[0005] The technical solution adopted by the present invention to solve the above-mentioned problem is: the circulation system described in the present invention includes a cylinder assembly, an air intake structure, an exhaust structure and an air storage structure; the air intake structure is connected to the air intake port of the cylinder assembly, and the exhaust port of the cylinder assembly is connected to the air storage structure through the exhaust structure.

[0006] Furthermore, the cylinder assembly includes a cylinder, a piston and a nozzle; the piston is arranged in the cylinder, the nozzle is installed in the middle of the top surface of the cylinder, the air inlet of the cylinder is connected to the air intake structure, and the exhaust port of the cylinder is connected to the air storage structure through the air intake structure.

[0007] Furthermore, the air inlet and the exhaust port are arranged on the top surface of the cylinder, and the air inlet and the exhaust port are respectively located on both sides of the nozzle.

[0008] Furthermore, the air intake structure includes an air intake pipe and an air intake valve. The air intake pipe is connected to the air intake port on the top surface of the cylinder, and the air intake valve is installed in the air intake pipe.

[0009] Furthermore, the exhaust structure includes an exhaust pipe and an exhaust valve, one end of the exhaust pipe is connected to the exhaust port on the top surface of the cylinder, the other end of the exhaust pipe is connected to the gas storage structure, and the exhaust valve is installed in the exhaust pipe.

[0010] Furthermore, the gas storage structure includes a gas storage tank and an exhaust manifold; the other end of the exhaust pipe is connected to the exhaust manifold, and the tank port of the gas storage tank is connected to the exhaust manifold.

[0011] Furthermore, the gas storage structure also includes a gas storage valve; the gas storage valve is installed in the tank mouth of the gas storage tank.

[0012] Furthermore, the gas storage structure also includes a control switch valve; the control switch valve is installed in the exhaust manifold, and the control switch valve is located between the tank port of the gas storage tank and the other end of the exhaust manifold.

[0013] The steps of the circulation method of the present invention include:

[0014] The piston in the cylinder moves upward to compress the gas. At this time, when the compressed gas reaches the top stop before the injection and combustion, the exhaust valve and the gas storage valve are opened, and the switch valve is controlled to be closed, so that part of the high-temperature and high-pressure gas generated by the compression in the cylinder can enter the gas storage tank for storage without leaking the gas. The gas storage tank stores part of the compressed high-temperature and high-pressure gas. After storing the gas, the gas storage valve and the exhaust valve are closed.

[0015] Furthermore, the remaining high-temperature and high-pressure gas in step 2 is sprayed into the cylinder and burned to cause the piston to move downward. At this time, the exhaust valve is closed, the gas storage valve is closed, and the control switch valve is closed to prevent gas leakage and ensure full combustion.

[0016] Furthermore, after the exhaust gas in the cylinder is discharged during the exhaust process and before the piston reaches the top dead center, the control switch valve is closed, the gas storage valve is opened, and the high-temperature and high-pressure gas stored in the gas tank is released. After the gas in the gas tank is released, it enters the cylinder, the exhaust valve is closed, the piston moves upward to compress the gas, and fuel injection and combustion are performed, so that the high-temperature and high-pressure gas released from the gas tank in step five is burned for the second time to do work, and the piston moves downward.

[0017] The beneficial effects of the present invention are:

[0018] 1. The whole cycle system of the traditional internal combustion engine has only one working process, and no work is done in the other processes, so the fuel utilization rate is not high. Different from the one-time combustion work of the traditional internal combustion engine, the present invention uses secondary combustion work to make the fuel burn fully, effectively utilize the large amount of excess heat energy generated in the combustion work process, and improve thermal efficiency.

[0019] 2. The greater the compression ratio of the present invention, the higher the pressure, which makes the thermal efficiency higher. However, the existing internal combustion engine causes concentrated over-temperature and high-pressure combustion of the combustible mixed gas due to the one-time combustion of fuel, which in turn causes explosion pressure phenomenon. High temperature will increase the content of emissions such as nitrogen oxides. Due to the pressure limitation, the intake conditions of the internal combustion engine will also be constrained to avoid excessive pressure causing excessive engine load and causing negative damage, thereby reducing the working capacity of the internal combustion engine.

[0020] 3. The present invention reduces the pressure limitation. Under the same pressure limitation conditions, the present invention can make the intake volume larger, the compression ratio higher, and the power and power density higher;

[0021] 4. The traditional circulation system generates a large amount of excess heat energy after one work, which will be directly released when the exhaust valve is opened at the end of the work stroke to perform the exhaust process, so that the residual heat after combustion is dissipated and cannot be fully utilized, thereby reducing the thermal efficiency of the overall cycle. The circulation system of the present invention performs one more combustion work process, thereby increasing the utilization rate of fuel, and improving the effective thermal efficiency and power;

[0022] 5. Compared with other working processes, the combustion cycle method of the present invention can increase the intake pressure under the same explosion pressure limit. The traditional combustion working process (the intake pressure is generally 3-5 bar) limits the intake pressure because the intake pressure is too high, which will lead to a large explosion pressure. Based on the 270 marine medium-speed engine (explosion pressure is 21.3MPa, intake pressure is 3.89bar), this working cycle method can increase the intake pressure to 5.89bar under the same explosion pressure conditions, effectively solving the limitation of explosion pressure, increasing the volume of compressed gas, and improving thermal efficiency;

[0023] 6. The working cycle method of the present invention is different from other two-stroke and four-stroke cycles (the traditional combustion cycle only performs combustion and work once), and is also different from other corresponding six-stroke cycles for exhaust after-treatment (water is sprayed into the cylinder after exhaust to utilize waste heat to do work). The combustion process is to burn compressed high-temperature and high-pressure gas, which has the advantage of two combustion and work, and increases the power density. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the structure of the present invention;

[0025] Figure 2 is a thermodynamic cycle flow chart of the method of the present invention;

[0026] Figure 3 It is a medium-speed diesel 270 single-cylinder GT-Power model;

[0027] Figure 4 It is a two-stage combustion model designed based on the single-cylinder GT-Power model of a medium-speed diesel engine;

[0028] Figure 5 It is the cylinder pressure diagram of the two-stage combustion process under multiple cycles;

[0029] Figure 6 It is a comparison chart between the in-cylinder pressure during the two-stage combustion process and the in-cylinder pressure of 270. DETAILED DESCRIPTION

[0030] Specific implementation method 1: Combination Figures 1 to 6 To illustrate this embodiment, a two-stage combustion multi-stroke cycle system with controllable intake and exhaust valves described in this embodiment includes a cylinder assembly, an intake structure, an exhaust structure and an air storage structure; the intake structure is connected to the intake port of the cylinder assembly, and the exhaust port of the cylinder assembly is connected to the air storage structure through the exhaust structure.

[0031] Specific implementation method 2: Combination Figures 1 to 6 This embodiment is described. The cylinder assembly of a two-stage combustion multi-stroke cycle system with controllable intake and exhaust valves described in this embodiment includes a cylinder 1, a piston 2 and a nozzle 3; the piston 2 is arranged in the cylinder 1, the nozzle 3 is installed in the middle of the top surface of the cylinder 1, the intake port of the cylinder 1 is connected to the intake structure, and the exhaust port of the cylinder 1 is connected to the gas storage structure through the intake structure. Other components and connection relationships are the same as those of the first embodiment.

[0032] Specific implementation method three: Combination Figures 1 to 6 To explain this embodiment, the intake port and the exhaust port of the controllable intake and exhaust valve two-stage combustion multi-stroke cycle system described in this embodiment are arranged on the top surface of the cylinder 1, and the intake port and the exhaust port are respectively located on both sides of the nozzle 3. Other components and connection relationships are the same as those of the second embodiment.

[0033] Specific implementation method four: Combination Figures 1 to 6 This embodiment is described. This embodiment is a controllable intake and exhaust valve two-stage combustion multi-stroke cycle system, characterized in that: the intake structure includes an intake pipe 4 and an intake valve 5, the intake pipe 4 is connected to the intake port on the top surface of the cylinder 1, and the intake valve 5 is installed in the intake pipe 4. Other components and connection relationships are the same as those of the first specific embodiment.

[0034] Specific implementation method five: Combination Figures 1 to 6 To explain this embodiment, the exhaust structure of the controllable intake and exhaust valve two-stage combustion multi-stroke cycle system described in this embodiment includes an exhaust pipe 6 and an exhaust valve 7, one end of the exhaust pipe 6 is connected to the exhaust port on the top surface of the cylinder 1, the other end of the exhaust pipe 6 is connected to the gas storage structure, and the exhaust valve 7 is installed in the exhaust pipe 6. Other components and connection relationships are the same as those of the specific embodiment 1.

[0035] Specific implementation method six: Combination Figures 1 to 6 To explain this embodiment, the gas storage structure of a two-stage combustion multi-stroke cycle system with controllable intake and exhaust valves described in this embodiment includes a gas storage tank 8 and an exhaust manifold 9; the other end of the exhaust pipe 6 is connected to the exhaust manifold 9, and the tank port of the gas storage tank 8 is connected to the exhaust manifold 9. Other components and connection relationships are the same as those of the specific embodiment one or five.

[0036] Specific implementation method seven: Combination Figures 1 to 6 To explain this embodiment, the gas storage structure of the controllable intake and exhaust valve two-stage combustion multi-stroke cycle system described in this embodiment further includes a gas storage valve 10; the gas storage valve 10 is installed in the tank mouth of the gas storage tank 8. Other components and connection relationships are the same as those of the specific embodiment 6.

[0037] Specific implementation method eight: Combination Figures 1 to 6 To explain this embodiment, the gas storage structure of the controllable intake and exhaust valve two-stage combustion multi-stroke cycle system described in this embodiment further includes a control switch valve 11; the control switch valve 11 is installed in the exhaust manifold 9, and the control switch valve 11 is located between the tank opening of the gas storage tank 8 and the other end of the exhaust manifold 9. Other components and connection relationships are the same as those of the specific embodiment 6.

[0038] Specific implementation method nine: Combination Figures 1 to 6 To illustrate this embodiment, a two-stage combustion multi-stroke cycle method with controllable intake and exhaust valves described in this embodiment is as follows:

[0039] The piston 2 in the cylinder 1 moves upward to compress the gas. At this time, when the compressed gas reaches the top stop before the injection and combustion, the exhaust valve 7 and the gas storage valve 10 are opened, and the switch valve 11 is controlled to be closed, so that part of the high-temperature and high-pressure gas generated by the compression in the cylinder 1 can enter the gas storage tank 8 for storage without leaking the gas. The gas storage tank 8 stores part of the compressed high-temperature and high-pressure gas. After storing the gas, the gas storage valve 10 and the exhaust valve 7 are closed.

[0040] Specific implementation method ten: Combination Figures 1 to 6 To explain the present embodiment, the present embodiment describes a two-stage combustion multi-stroke cycle method with controllable intake and exhaust valves. The high-temperature and high-pressure gas remaining in step 2 is injected into the cylinder 1 for combustion, and the working piston 2 moves downward. At this time, the exhaust valve 7 is closed, the gas storage valve 10 is closed, and the switch valve 11 is controlled to be closed to avoid gas leakage and ensure its full combustion.

[0041] Specific implementation method eleven: Combination Figures 1 to 6The present embodiment is described. The present embodiment describes a method for two-stage combustion and multi-stroke cycle with controllable intake and exhaust valves. When the exhaust gas in the cylinder 1 is discharged during the exhaust process and before the piston 2 reaches the top dead center, the control switch valve 11 is closed, the gas storage valve 10 is opened, and the high-temperature and high-pressure gas stored in the gas tank 8 is released. After the gas in the gas tank 8 is released, the gas enters the cylinder 1, the exhaust valve 7 is closed, the piston 2 moves upward to compress the gas, and fuel injection combustion is performed, so that the high-temperature and high-pressure gas released from the gas tank 8 in step five is burned for the second time to perform work, and the piston 2 moves downward.

[0042] How it works

[0043] Step 1: First, the intake process is performed, and the gas enters the cylinder 1. After the stroke is completed, the piston 2 in the cylinder 1 moves upward to compress the gas. When the compressed gas reaches the top stop, the gas storage process is performed before the fuel injection and combustion, so that part of the high-temperature and high-pressure gas generated by the compression in the cylinder 1 can enter the gas storage tank 8 without leaking the gas. The gas storage tank 8 stores part of the compressed high-temperature and high-pressure gas;

[0044] Step 2: After a portion of gas is stored in the gas storage tank 8, the remaining high-temperature and high-pressure gas in the cylinder 1 in step 1 is burned after the fuel injection, and the piston 2 moves downward to do work. When the piston 2 reaches the bottom dead center, it is ready to discharge the gas generated after the first combustion, and the first exhaust process is performed;

[0045] Step three: before the piston 2 reaches the top dead center during the exhaust process, the high-temperature and high-pressure gas stored in the gas tank 8 is released. After the gas in the gas tank 8 is released, the piston 2 moves upward to compress the gas, and then sprays oil into the cylinder 1, so that the high-temperature and high-pressure gas released from the gas tank 8 undergoes a second combustion and work. The piston 2 moves downward to the bottom dead center, ready to discharge the exhaust gas generated after the second combustion, and performs the second exhaust process.

[0046] Example

[0047] Verification using a single-cylinder diesel engine model built by GT-Power

[0048] Step 1: Establish the GT-Power model of a 270 marine medium-speed diesel engine with a single cylinder; refer to the GT-Power model of a medium-speed diesel engine with a single cylinder. Figure 3 ;

[0049] Table 1 shows the main parameters required to build the GT-Power model:

[0050] Table 1 Basic parameters of modeling

[0051]

[0052] Step 2: Set a gas tank with a gas storage valve on the exhaust manifold after the gas comes out of the cylinder exhaust valve, and set a control switch valve behind the gas tank valve on the exhaust manifold. By controlling the opening and closing time of each valve, the designed cycle process is achieved. The two-stage combustion model is established by GT-Power based on the established 270 single-cylinder model. Figure 4 As shown, this cycle starts from -180° crankshaft angle and ends at 900°. This thermal working cycle consists of three two-stroke cycles. Since there is only one intake process, the intake valve only needs to be opened and closed once; the exhaust valve needs to be opened each time the gas tank stores and releases gas, and there is also an exhaust process, so the exhaust valve needs to be opened and closed three times; this cycle has two combustion processes, requiring two injection settings; settings are required when the gas tank stores and releases gas, and there are two opening and closing time settings. During the compression stroke, before reaching the top point and before the exhaust valve is closed, the gas tank valve is opened to store the compressed high-temperature and high-pressure gas. After closing the valve, the remaining gas undergoes a combustion process. After the second piston upward exhaust, the compression process is carried out. Before the exhaust valve is closed, the gas storage valves are opened to release the stored high-temperature and high-pressure gas, and then the valves are closed to continue the compression process, preparing for the second combustion process; the control switch valve of the exhaust manifold is used to control the cyclic exhaust process and prevent leakage during the storage and release of gas in the gas tank.

[0053] Step 3: Use the model to verify the operation of the design process under 100% working conditions. Since this design cycle has a larger intake air demand than the 270 model, the intake air pressure during operation is increased accordingly, such as Figure 5 The figure shows the operation of ten cycles. The first cycle is quite different from the others and has no reference value. However, the results show that the designed cycle can run stably.

[0054] This example uses the GT-Power model of a single cylinder of a 270 medium-speed marine diesel engine. The calibrated single-cylinder model of a medium-speed marine diesel engine is operated under 100% load conditions. A two-stage combustion model based on controllable intake and exhaust valves is established. The cylinder pressure curve output by the joint simulation result is compared with the cylinder pressure curve of the 270 model. Figure 6 As shown, the second combustion work was carried out in a stable operation based on the same maximum pressure of the first combustion stage as that of the 270 model.

[0055] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement made to the above embodiments without departing from the content of the technical solution of the present invention, based on the technical essence of the present invention, within the spirit and principles of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims

1. A two-stage combustion multi-stroke cycle method of a two-stage combustion multi-stroke cycle device with controllable intake and exhaust valves, characterized in that: A two-stage combustion multi-stroke circulation system of a two-stage combustion multi-stroke circulation device with controllable intake and exhaust valves used in the invention comprises a cylinder assembly, an intake structure, an exhaust structure and an air storage structure; the intake structure is connected to the intake port of the cylinder assembly, and the exhaust port of the cylinder assembly is connected to the air storage structure through the exhaust structure; The cylinder assembly comprises a cylinder (1), a piston (2) and a nozzle (3); the piston (2) is arranged in the cylinder (1), the nozzle (3) is installed in the middle of the top surface of the cylinder (1), the air inlet of the cylinder (1) is connected to the air inlet structure, and the air outlet of the cylinder (1) is connected to the air storage structure through the air inlet structure; The air inlet and the exhaust port are arranged on the top surface of the cylinder (1), and the air inlet and the exhaust port are respectively located on both sides of the nozzle (3); The air intake structure comprises an air intake pipe (4) and an air intake valve (5); the air intake pipe (4) is in communication with an air intake port on the top surface of the cylinder (1); and the air intake valve (5) is installed in the air intake pipe (4); The exhaust structure comprises an exhaust pipe (6) and an exhaust valve (7); one end of the exhaust pipe (6) is in communication with an exhaust port on the top surface of the cylinder (1); the other end of the exhaust pipe (6) is connected to the gas storage structure; and the exhaust valve (7) is installed in the exhaust pipe (6); The gas storage structure comprises a gas storage tank (8) and an exhaust manifold (9); the other end of the exhaust pipe (6) is connected to the exhaust manifold (9), and the tank opening of the gas storage tank (8) is in communication with the exhaust manifold (9); The gas storage structure further comprises a gas storage valve (10); the gas storage valve (10) is installed in the tank opening of the gas storage tank (8); The gas storage structure further comprises a control switch valve (11); the control switch valve (11) is installed in the exhaust manifold (9), and the control switch valve (11) is located between the tank opening of the gas storage tank (8) and the other end of the exhaust manifold (9); The steps of the two-stage combustion multi-stroke cycle method of the two-stage combustion multi-stroke cycle device with controllable intake and exhaust valves include: The piston (2) in the cylinder (1) moves upward to compress the gas. At this time, when the compressed gas reaches the upper end stop before the fuel injection and combustion, the exhaust valve (7) and the gas storage valve (10) are opened, and the switch valve (11) is controlled to be closed, so that part of the high-temperature and high-pressure gas generated by the compression in the cylinder (1) can enter the gas storage tank (8) for storage without leaking the gas. The gas storage tank (8) stores part of the compressed high-temperature and high-pressure gas. After the gas is stored, the gas storage valve (10) and the exhaust valve (7) are closed; The remaining high-temperature and high-pressure gas in the cylinder (1) is sprayed with oil and burned to cause the piston (2) to move downward. At this time, the exhaust valve (7) is closed, the gas storage valve (10) is closed, and the control switch valve (11) is closed to prevent gas leakage and ensure full combustion. After the exhaust gas in the cylinder (1) is discharged during the exhaust process and before the piston (2) reaches the top dead center, the control switch valve (11) is closed, the gas storage valve (10) is opened, and the high-temperature and high-pressure gas stored in the gas storage tank (8) is released. After the gas in the gas storage tank (8) is released, it enters the cylinder (1), the exhaust valve (7) is closed, the piston (2) moves upward to compress the gas, and the fuel injection combustion is performed, so that the high-temperature and high-pressure gas released from the gas storage tank (8) is burned for the second time to perform work, and the piston (2) moves downward.

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