A new multi-mode variable cycle two-stroke piston engine

Abstract

The application discloses a novel multi-mode variable cycle two-stroke piston engine, which is used for an aviation compound power system of shaft power and gas output modes and belongs to the technical field of aero-engines. The novel multi-mode variable cycle two-stroke piston engine comprises a spark plug, a cylinder, a scavenging port, a piston, a crankcase, a crankcase exhaust port, a crankcase exhaust electric control one-way valve, an air inlet, a main exhaust port, a supplementary combustion chamber, a supplementary combustion agent inlet, a cylinder top exhaust port and a cylinder top exhaust electric control one-way valve. The novel multi-mode variable cycle two-stroke piston engine is provided with an exhaust pipe provided with an electric control one-way valve at the top of the cylinder and the crankcase based on a conventional two-stroke engine. In the shaft power output mode, the cylinder top exhaust port and the crankcase exhaust port are closed, the original two-stroke piston engine shaft power output working mode and performance are retained, in the gas output mode, the electric control one-way valve opens all the exhaust ports, high-pressure gas is basically discharged during the up-and-down movement of the piston, and the engine becomes a gas generator at this time, which can be used for wing tip jet power or an APU of an aero-engine.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aero-engines, in particular to a new multi-mode variable cycle two-stroke piston engine. BACKGROUND

[0002] Aero-piston engines have the outstanding advantages of low cost and low specific fuel consumption, but also have the fatal disadvantage of high power-to-weight ratio. In addition, some composite aero power such as wingtip jet rotor has the comprehensive demand of gas output and shaft power output, so the research and development of aero-piston engine with high power-to-weight ratio, low specific fuel consumption and multiple power output is urgent.

[0003] At present, the power-to-weight ratio of XRDi200cc, a high power-to-weight ratio aero-heavy oil piston engine under research internationally, is 2, the power-to-weight ratio of Hangrui-Yunqiao is 1.41, the power-to-weight ratio of Zongshen C08 / 12H is 1.42, and the power-to-weight ratio of the latest 28kW small heavy oil piston engine with low fuel consumption and high power-to-weight ratio developed by the team of Beijing University of Aeronautics and Astronautics is 1.47, which is far lower than the power-to-weight ratio of about 5 of aero-gas turbine (Ding Shuiting, Song Yue, Du Farong, et al. Development trend and key technology analysis of aero-heavy oil piston engine [J]. Journal of Aerospace Power, 2021, 36(6): 1121-1136).

[0004] At present, all aero-piston engines are only single shaft power output, and for wingtip jet, APU and other occasions that need gas power, they are helpless, and sometimes they have to use turbine piston combined power system, but since two sets of core components of piston engine and turbine are needed, it is obvious that the power-to-weight ratio and cost are not ideal; there are also attempts to increase external pressure boosting system to improve power-to-weight ratio and output gas, but the effect is minimal. SUMMARY

[0005] Therefore, the present application provides a new multi-mode variable cycle two-stroke piston engine, which breaks through the structure and principle of traditional aero-piston engines and proposes a high power-to-weight ratio low specific fuel consumption aero-composite power system with shaft power and gas output modes.

[0006] In order to achieve the above purpose, the present application provides the following technical scheme:

[0007] A new multi-mode variable cycle two-stroke piston engine, comprising a cylinder and a spark plug arranged at the top of the cylinder, further comprising a crankcase, a piston, a scavenging port, an air inlet, a main exhaust port, a first exhaust assembly and a second exhaust assembly.

[0008] The crankcase is arranged below the cylinder, the crankcase is drivingly connected to the piston arranged in the cylinder, one side of the cylinder is provided with a scavenging port, the other side of the cylinder is provided with an intake port and a main exhaust port, the top of the cylinder is provided with a second exhaust assembly, the first exhaust assembly is arranged on the crankcase, and the first exhaust assembly and the second exhaust assembly are communicated with the main exhaust port.

[0009] Preferably, the first exhaust assembly, the second exhaust assembly and the main exhaust port are communicated with a supplemental combustion chamber, and a supplemental combustion agent inlet is arranged on the supplemental combustion chamber.

[0010] Preferably, the first exhaust assembly comprises a crankcase exhaust port, a crankcase exhaust electrically-controlled one-way valve and a first exhaust pipeline, the crankcase exhaust port is arranged at the inlet of the first exhaust pipeline, and the crankcase exhaust electrically-controlled one-way valve is arranged at the outlet of the first exhaust pipeline.

[0011] Preferably, the second exhaust assembly comprises a cylinder top exhaust port, a cylinder top exhaust electrically-controlled one-way valve and a second exhaust pipeline, the cylinder top exhaust port is arranged at the inlet of the second exhaust pipeline, and the cylinder top exhaust electrically-controlled one-way valve is arranged at the outlet of the second exhaust pipeline.

[0012] Preferably, in the shaft power output mode, the crankcase exhaust port and the cylinder top exhaust port are closed, the working mode and performance thereof are the same as those of a typical two-stroke piston engine, and the thermodynamic cycle thereof is an Otto cycle of a typical spark-ignition piston engine.

[0013] Preferably, in the gas output mode, the piston compresses the gas in the cylinder and the gas in the crankcase in a bidirectional manner, after the piston moves upward to above the intake port, the intake port is opened, fresh air enters the crankcase, ignition is started when the piston approaches the top end of the cylinder but has not yet moved to close the cylinder top exhaust port, at this time, the cylinder top exhaust port is exhausted under the control of the cylinder top exhaust electrically-controlled one-way valve, so that the process is constant-pressure combustion.

[0014] The piston continues to move upward to completely close the cylinder top exhaust port in the constant-pressure combustion process, the piston stops at the top dead center, and then the combustion process in the cylinder is constant-volume combustion, and the thermodynamic cycle thereof is a similar Atkinson cycle with the sequence of heating process being reversed.

[0015] Preferably, after the combustion is completed, the piston subsequently moves downward under the pushing of high-pressure gas, and the high-temperature and high-pressure gas after combustion is exhausted from the cylinder top exhaust port under the control of the cylinder top exhaust electrically-controlled one-way valve.

[0016] Meanwhile, when the piston is descending, the gas in the crankcase is discharged from the crankcase exhaust port under the control of the crankcase exhaust electrically-controlled one-way valve; when the piston descends to below the main exhaust port and the scavenging port, the gas in the cylinder and part of the scavenging gas are discharged from the main exhaust port and the cylinder top exhaust port, and the high-pressure gas is output during the whole descending process of the piston.

[0017] Preferably, when the piston is ascending from the bottom dead center, the high-pressure gas in the crankcase is continuously discharged through the crankcase exhaust port under the control of the crankcase exhaust electrically-controlled one-way valve until the pressure is reduced to open the intake port to intake gas;

[0018] Then, the piston continues to ascend, and the high-pressure gas in the cylinder is discharged through the cylinder top exhaust port under the control of the cylinder top exhaust electrically-controlled one-way valve until the piston approaches the top dead center to close the cylinder top exhaust port, and the high-pressure gas is output during the whole ascending process of the piston.

[0019] Preferably, in the gas output mode, the two-stroke piston engine becomes a compressor and a combustion chamber, and can continuously output gas like a gas turbine, and the piston and the crankshaft do not absorb mechanical work, but only maintain the movement of the piston, that is, the piston engine becomes a gas generator capable of continuously discharging gas.

[0020] Preferably, in the gas output mode, the three exhaust pipes are all collected in the external combustion chamber, and a combustion supplement such as hydrogen peroxide is injected into the combustion chamber to increase the amount of gas generated through further vaporization and heat release of the combustion supplement, and to supplement the unburned oil gas in the engine exhaust.

[0021] The present application has the following advantages:

[0022] The present application innovates the structure and principle of the traditional two-stroke aviation piston engine, and enables the two-stroke piston engine to have and switch to the gas output function as needed on the premise of retaining the original shaft power output function, so as to realize the typical Otto cycle and the variable cycle similar to the SABRE cycle, respectively, and has the advantages of simple structure, high power-to-weight ratio, and low fuel consumption, and has outstanding advantages and broad application prospects in wingtip jet rotor power, APU power, and similar aviation power systems. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only exemplary, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the provided drawings.

[0024] The structures, proportions, sizes, etc. shown in the specification are only used to cooperate with the content disclosed in the specification, so that those skilled in the art can understand and read, and are not used to limit the conditions that can be implemented by the application, so they do not have technical significance. Any modification of structure, change of proportion relationship or adjustment of size, without affecting the effect and purpose that can be achieved by the application, should still fall within the scope of the technology disclosed by the application.

[0025] Figure 1 The overall structure of the application is shown in the schematic diagram.

[0026] Figure 2 The schematic diagram of the piston upstroke in the application is shown in the schematic diagram.

[0027] Figure 3 The schematic diagram of the isobaric combustion of the application is shown in the schematic diagram.

[0028] Figure 4 The schematic diagram of the isochoric combustion of the application is shown in the schematic diagram.

[0029] Figure 5 The schematic diagram of the piston downstroke in the application is shown in the schematic diagram.

[0030] Figure 6 The schematic diagram of the scavenging exhaust in the application is shown in the schematic diagram.

[0031] Figure 7 The schematic diagram of the variable cycle thermodynamic cycle of the application is shown in the schematic diagram.

[0032] In the figure:

[0033] 1 spark plug; 2 cylinder; 3 scavenging port; 4 piston; 5 crankcase; 6 crankcase exhaust port; 7 intake port; 8 crankcase exhaust electrically controlled one-way valve; 9 main exhaust port; 10 supplementary combustion chamber; 11 supplementary combustion agent inlet; 12 cylinder head exhaust electrically controlled one-way valve; 13 cylinder head exhaust port. DETAILED DESCRIPTION

[0034] The embodiments of the application are described below by specific examples, and those skilled in the art can easily understand other advantages and effects of the application from the content disclosed in the specification. Obviously, the described examples are part of the examples of the application, not all. Based on the examples in the application, all other examples obtained by those skilled in the art without creative labor fall within the scope of the application.

[0035] In order to solve the related technical problems existing in the prior art, the embodiment of the application provides a new two-stroke variable cycle engine, which aims to solve the problem that the power-to-weight ratio of the traditional aviation piston engine is large and cannot provide the required fuel gas for some aviation power. As Figure 1As shown, specifically includes cylinder 2 and set in the cylinder 2 top spark plug 1, also includes crankcase 5, piston 4, scavenging port 3, intake port 7, main exhaust port 9, first exhaust assembly and second exhaust assembly;

[0036] The crankcase 5 is arranged in the lower part of the cylinder 2, the crankcase 5 transmission connection is arranged in the piston 4 of the cylinder 2, the cylinder 2 side is provided with scavenging port 3, the other side of the cylinder 2 is provided with intake port 7 and main exhaust port 9, the top of the cylinder 2 is provided with the second exhaust assembly, the first exhaust assembly is arranged on the crankcase 5, the first exhaust assembly and the second exhaust assembly are communicated with the main exhaust port 9.

[0037] Wherein, it also includes a supplemental combustion chamber 10 and a supplemental combustion agent inlet 11, the first exhaust assembly, the second exhaust assembly and the main exhaust port 9 are collected and communicated with the supplemental combustion chamber 10, and the supplemental combustion chamber 10 is provided with the supplemental combustion agent inlet 11.

[0038] Preferably, the first exhaust assembly includes a crankcase exhaust port 6, a crankcase exhaust electrically controlled one-way valve 8 and a first exhaust pipeline, the first exhaust pipeline inlet is provided with the crankcase exhaust port 6, and the first exhaust pipeline outlet is provided with the crankcase exhaust electrically controlled one-way valve 8.

[0039] Preferably, the second exhaust assembly includes a cylinder top exhaust port 13, a cylinder top exhaust electrically controlled one-way valve 12 and a second exhaust pipeline, the second exhaust pipeline inlet is provided with the cylinder top exhaust port 13, and the second exhaust pipeline outlet is provided with the cylinder top exhaust electrically controlled one-way valve 12.

[0040] The above three exhaust pipes can ensure that the high-pressure gas and high-pressure air are continuously collected in the supplemental combustion chamber 10 for further supplemental combustion and pressure increase; the supplemental combustion chamber 10 has a hydrogen peroxide type supplemental combustion agent injection and high-temperature gas vaporization reaction to further increase the gas amount and pressure, supplement the combustion of unburned oil gas, reduce pollution emission and improve combustion efficiency.

[0041] In the shaft power output mode of the embodiment, the crankcase exhaust port 6 and the cylinder top exhaust port 13 are closed, the working mode and performance thereof are the same as those of a typical two-stroke piston engine, and details are not repeated, and the thermodynamic cycle thereof is a typical Otto cycle of a spark-ignition piston engine, such as Figure 7 The typical Otto cycle 0-1-2-3-4-1.

[0042] In the gas output mode, the piston 4 bidirectionally compresses the gas in the cylinder 2 and the gas in the crankcase 5, the piston 4 goes up, corresponding to Figure 7 The process 1-2' in the similar Sabathe cycle; after the piston 4 goes up above the intake port 7, the intake port 7 is opened, and fresh air enters the crankcase 5, such as Figure 2As shown; when the piston 4 approaches the top end of the cylinder 2 but has not yet moved to close the cylinder top exhaust port 13, the ignition of combustion is started, as shown in Fig. 2a, at this time, because the cylinder top exhaust port 13 is under the control of the cylinder top exhaust electrically controlled one-way valve 12, the process is constant pressure combustion, corresponding to Figure 3 2'-2.5 process similar to the Atkinson cycle. The piston 4 continues to go up during the constant pressure combustion process until the cylinder top exhaust port 13 is closed, the piston 4 stops at the top top dead center, and the subsequent combustion is a constant volume combustion process, as shown in Fig. 2b, corresponding to Figure 7 2.5-3' process similar to the Atkinson cycle. Figure 4 2'-2.5 process similar to the Atkinson cycle. The piston 4 continues to go up during the constant pressure combustion process until the cylinder top exhaust port 13 is closed, the piston 4 stops at the top top dead center, and the subsequent combustion is a constant volume combustion process, as shown in Fig. 2b, corresponding to Figure 7 2.5-3' process similar to the Atkinson cycle. Figure 7 2'-2.5 process similar to the Atkinson cycle. The piston 4 continues to go up during the constant pressure combustion process until the cylinder top exhaust port 13 is closed, the piston 4 stops at the top top dead center, and the subsequent combustion is a constant volume combustion process, as shown in Fig. 2b, corresponding to

[0043] After the combustion is completed, the piston 4 then goes down under the push of high pressure gas, and the high temperature and high pressure gas after combustion is discharged from the cylinder 2 through the cylinder top exhaust port 13 under the control of the cylinder top exhaust electrically controlled one-way valve 12;

[0044] At the same time, when the piston 4 goes down to compress the gas in the crankcase 5, the gas in the crankcase 5 is discharged from the crankcase 5 through the crankcase exhaust port 6 under the control of the crankcase exhaust electrically controlled one-way valve 8; when the piston 4 goes down to below the main exhaust port 9 and the scavenging port 3, the gas in the cylinder 2 and part of the scavenging gas are discharged from the main exhaust port 9 and the cylinder top exhaust port 13, and there is gas or high pressure gas output during the entire piston downstroke. That is, the piston 4 then goes down under the push of high pressure gas, as shown in Fig. 2c, and the high temperature and high pressure gas after combustion expands, corresponding to Figure 5 2.5-3' process similar to the Atkinson cycle. Figure 7 2'-2.5 process similar to the Atkinson cycle. The piston 4 continues to go up during the constant pressure combustion process until the cylinder top exhaust port 13 is closed, the piston 4 stops at the top top dead center, and the subsequent combustion is a constant volume combustion process, as shown in Fig. 2b, corresponding to Figure 6 , the intake port 7 is closed, the scavenging port 3 is opened, the crankcase exhaust port 6 is opened under the control of the crankcase exhaust electrically controlled one-way valve 8, the main exhaust port 9 is opened, the cylinder top exhaust port 13 is opened under the control of the cylinder top exhaust electrically controlled one-way valve 12, part of the gas in the crankcase 5 enters the cylinder 2, and part of the gas is discharged from the crankcase exhaust port 6, and the gas in the cylinder 2 is discharged from the main exhaust port 9 and the cylinder top exhaust port 13.

[0045] Preferably, when the piston starts to go up from the bottom dead center, the high pressure gas in the crankcase continues to be discharged through the crankcase exhaust port under the control of the crankcase exhaust electrically controlled one-way valve until the pressure decreases to negative pressure to open the intake port to intake air;

[0046] The piston then continues to move upward, and the high-pressure gas in the cylinder can be discharged through the cylinder top exhaust port under the control of the cylinder top exhaust electronic check valve until the piston approaches the top dead center and closes the cylinder top exhaust port. Throughout the piston's upward movement, there is high-pressure gas or combustion gas output.

[0047] Preferably, in the gas output mode, the two-stroke piston engine transforms into a compressor and combustion chamber, capable of continuously outputting gas like a gas turbine. At the same time, the piston and crankshaft do not absorb mechanical work, but only maintain their own piston movement. That is, the piston engine becomes a gas generator capable of continuous exhaust at this time.

[0048] Preferably, in the gas output mode, all three exhaust pipes converge into the external combustion chamber 10 of the cylinder, and by injecting a combustion agent such as hydrogen peroxide into the combustion chamber 10, the amount of gas generated is increased through the further vaporization and exothermic reaction of the combustion agent such as hydrogen peroxide, while supplementing the combustion of unburned oil and gas in the engine exhaust.

[0049] This invention innovates the structural principle of traditional two-stroke aero piston engines, enabling them to retain the original shaft power output function while also having the ability to switch to gas output function as needed. This allows for the implementation of both the typical Otto cycle and the Sabart cycle-like variable cycle operation of a two-stroke piston engine. The invention features a simple structure, high power-to-weight ratio, and low fuel consumption, demonstrating significant advantages and broad application prospects in wingtip jet rotor power, APU power, and similar aero propulsion systems.

[0050] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A novel multi-mode variable cycle two-stroke piston engine, comprising a cylinder (2) and a spark plug (1) disposed at the top of the cylinder (2), characterized in that, It also includes a crankcase (5), piston (4), scavenging port (3), intake port (7), main exhaust port (9), first exhaust assembly and second exhaust assembly; The crankcase (5) is located at the lower part of the cylinder (2). The crankcase (5) is connected to the piston (4) located in the cylinder (2). A scavenging port (3) is provided on one side of the cylinder (2). An air inlet (7) and a main exhaust port (9) are provided on the other side of the cylinder (2). A second exhaust assembly is provided at the top of the cylinder (2). A first exhaust assembly is provided on the crankcase (5). Both the first exhaust assembly and the second exhaust assembly are connected to the main exhaust port (9). The first exhaust assembly includes a crankcase exhaust port (6), a crankcase exhaust electronic check valve (8), and a first exhaust pipe. The first exhaust pipe has a crankcase exhaust port (6) at its inlet and a crankcase exhaust electronic check valve (8) at its outlet. The second exhaust assembly includes a cylinder top exhaust port (13), a cylinder top exhaust electronic check valve (12), and a second exhaust pipe. The cylinder top exhaust port (13) is provided at the inlet of the second exhaust pipe, and the cylinder top exhaust electronic check valve (12) is provided at the outlet of the second exhaust pipe.

2. The novel multi-mode variable cycle two-stroke piston engine as described in claim 1, characterized in that, It also includes a combustion chamber (10) and a combustion agent inlet (11). The first exhaust assembly, the second exhaust assembly and the main exhaust port (9) converge and connect to the combustion chamber (10). The combustion chamber (10) is provided with a combustion agent inlet (11).

3. The novel multi-mode variable cycle two-stroke piston engine as described in claim 1, characterized in that, When the crankcase exhaust port (6) and cylinder top exhaust port (13) are closed during shaft power output operation, the operation mode and performance are the same as those of a typical two-stroke piston engine, and its thermodynamic cycle is the typical Otto cycle of a spark-ignition piston engine.

4. The novel multi-mode variable cycle two-stroke piston engine as described in claim 1, characterized in that, In the gas output mode, the piston (4) compresses the gas in the cylinder (2) and the gas in the crankcase (5) in both directions. After the piston (4) moves up to above the air inlet (7), the air inlet (7) opens and fresh air enters the crankcase (5). When the piston (4) approaches the top of the cylinder (2) but has not yet moved to close the cylinder top exhaust port (13), ignition and combustion begin. At this time, the cylinder top exhaust port (13) exhausts gas under the control of the cylinder top exhaust electronic control check valve (12). Therefore, this process is constant pressure combustion. During the isobaric combustion process, the piston (4) continues to move upward until the cylinder top exhaust port (13) is completely closed. The piston (4) stops at the top dead center. After that, the combustion process in the cylinder (2) is constant volume combustion. Its thermodynamic cycle is similar to the Sabart cycle, which is the opposite of the Sabart cycle heating process, first constant pressure heating and then constant volume heating.

5. The novel multi-mode variable cycle two-stroke piston engine as described in claim 4, characterized in that, After combustion ends, the piston (4) then moves downward under the push of the high-pressure gas. The high-temperature and high-pressure gas after combustion is discharged from the cylinder (2) through the cylinder top exhaust port (13) under the control of the cylinder top exhaust electronic check valve (12). At the same time, when the piston (4) descends and compresses the gas in the crankcase (5), the gas in the crankcase (5) is discharged from the crankcase exhaust port (6) under the control of the crankcase exhaust electronic check valve (8); when the piston (4) descends to below the main exhaust port (9) and the scavenging port (3), the gas in the cylinder (2) and part of the scavenging gas are discharged from the main exhaust port (9) and the cylinder top exhaust port (13). There is gas or high-pressure gas output throughout the piston's downward movement.

6. The novel multi-mode variable cycle two-stroke piston engine as described in claim 5, characterized in that, When the piston (4) moves upward from the bottom dead center, the high-pressure gas in the crankcase (5) continues to be discharged through the crankcase exhaust port (6) under the control of the crankcase exhaust electronic check valve (8) until the pressure drops to negative pressure and the intake port (7) is opened to allow air to enter. Then the piston (4) continues to move upward, and the high-pressure gas in the cylinder can be discharged through the cylinder top exhaust port (13) under the control of the cylinder top exhaust electronic control check valve (12) until the piston (4) closes the cylinder top exhaust port (13) when it approaches the top dead center. The piston outputs high-pressure gas or combustion gas during the entire upward process.

7. The novel multi-mode variable cycle two-stroke piston engine as described in claim 1, characterized in that, In gas output mode, the two-stroke piston engine transforms into a compressor and combustion chamber, capable of continuously outputting gas like a gas turbine. At the same time, the piston and crankshaft do not absorb mechanical work, but only maintain their own piston movement. In other words, the piston engine becomes a gas generator capable of continuous exhaust at this time.

8. The novel multi-mode variable cycle two-stroke piston engine as described in claim 1, characterized in that, In the gas output mode, all three exhaust pipes converge into the external combustion chamber (10) of the cylinder. By injecting a combustion agent such as hydrogen peroxide into the combustion chamber (10), the amount of gas generated is increased through the further vaporization and exothermic reaction of the combustion agent such as hydrogen peroxide, and at the same time, the unburned oil and gas in the engine exhaust are supplemented for combustion.

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