Internal combustion engine for realizing compression ratio and expansion ratio decoupling

Abstract

An internal combustion engine for achieving compression ratio and expansion ratio decoupling is characterized in that the internal combustion engine is composed of an independent compressor and an independent expansion machine, an intercooler and a combustion chamber are arranged between a compressor air cylinder and an expansion machine air cylinder, and the intercooler and the combustion chamber are connected through a pipeline and a valve system. Separation of the compressor from the expander decouples the compression ratio and the expansion ratio, thereby forming a low compression ratio and an ultra-high expansion ratio. For example, when the compression ratio is 10: 1, the expansion ratio can reach 30: 1. In particular, the internal combustion engine has a new combustion mode, which has a strong ability to resist knocking.

Description

Technical Field

[0001] The present invention relates to the field of internal combustion engines, and in particular to an internal combustion engine that realizes decoupling of compression ratio and expansion ratio, and is a thermodynamic cycle technology that couples multiple excellent thermodynamic processes. Background Art

[0002] The efficiency of internal combustion engines mainly depends on the expansion ratio and lean burn or high EGR rate combustion technology. As we all know, the maximum efficiency of gasoline engines at this stage is about 40%, and the rest of the energy is lost through the heat dissipation of the water tank and the discharge of high-temperature exhaust gas.

[0003] The high expansion ratio greatly reduces the exhaust gas temperature and saves the heat energy loss of exhaust gas emissions. By increasing the EGR rate or low-temperature combustion through lean burn technology, the heat energy loss conducted to the outside can be greatly reduced.

[0004] Gasoline engines cannot increase compression and expansion ratios due to knocking during combustion. It is also very difficult to reduce combustion temperature by increasing the EGR rate or performing lean gas combustion. Due to the flat shape of the combustion chamber, it is difficult to organize airflow movement, the flame propagation distance is long, and the high EGR rate greatly reduces the flame propagation speed. Therefore, combustion cannot be completed in a short time, making it difficult to achieve perfect low-temperature combustion technology. The above "low expansion ratio" and "high-temperature combustion" are the two main factors that have kept the maximum efficiency of gasoline engines at around 40% for a long time and cannot be improved. Summary of the invention

[0005] The technical solution of the present invention is to provide an internal combustion engine that realizes decoupling of compression ratio and expansion ratio, which is composed of at least one compressor and at least two expanders, wherein the compressor is a single-stage compressor composed of one cylinder, or a two-stage compressor composed of two cylinders, and the two expanders are composed of two parallel cylinders. It is characterized in that the number of the compressors and the number of the expanders is 1:2, and the cylinder volume of the compressor is equal to or unequal to the cylinder volume of the expander; the compressor piston and the expander piston are driven by the same crankshaft so that they reciprocate between their respective top dead center and bottom dead center; an intercooler and a combustion chamber are sequentially arranged between the compressor cylinder and the expander cylinder of the internal combustion engine, and each combustion chamber corresponds to an expander cylinder connected thereto, and they are connected by pipelines and valve systems;

[0006] With the reciprocating motion of the compressor piston and the expander piston and the timing of the opening and closing of the valve system, the compressor cylinder completes the intake stroke and compression stroke of the internal combustion engine, the compressed gas is sent to the intercooler for cooling, and then sent to the combustion chamber for combustion, and the generated high-temperature and high-pressure gas is sprayed into the expander cylinder to complete the expansion stroke and exhaust stroke;

[0007] The operation of the internal combustion engine consists of a complete thermodynamic cycle consisting of an intake stroke, a compression stroke, an intermediate cooling process, a combustion process, an expansion stroke and an exhaust stroke, and is completed by the same crankshaft in a 360-degree rotation.

[0008] Furthermore, the internal combustion engine has three in-line cylinders, including a compressor cylinder and two expander cylinders connected in parallel; the crankshaft of the internal combustion engine has three cranks, which respectively drive a compressor piston and two expander pistons to make them reciprocate.

[0009] Furthermore, the internal combustion engine has four in-line cylinders, wherein: two cylinders constitute a two-stage compressor, and the other two cylinders are parallel expander cylinders; the first-stage compressor cylinder, the second-stage compressor cylinder and the two expander cylinders of the two-stage compressor are arranged in parallel; the crankshaft of the internal combustion engine has four cranks, which respectively drive two compressor pistons and two expander pistons to make them reciprocate.

[0010] Furthermore, the internal combustion engine has four cylinders, wherein: two cylinders constitute a two-stage compressor, and the other two cylinders are parallel expander cylinders; wherein the second-stage cylinder of the two-stage compressor is placed on the first-stage compressor cylinder of the two-stage compressor to form a stacked structure; the crankshaft of the internal combustion engine has three cranks, which respectively drive a stacked two-stage compressor piston and two expander pistons to make them reciprocate.

[0011] Furthermore, the technical solution of the present invention provides an internal combustion engine that realizes decoupling of compression ratio and expansion ratio, characterized in that the internal combustion engine has three cylinders, wherein: two cylinders constitute a two-stage compressor, and the other cylinder is an expander cylinder; the second-stage cylinder of the two-stage compressor is placed on the first-stage compressor cylinder of the two-stage compressor to form a stacked structure; the crankshaft of the internal combustion engine has two cranks, which respectively drive a stacked two-stage compressor piston and an expander piston to make them reciprocate.

[0012] Furthermore, the crankshaft of the internal combustion engine has a plane crankshaft with three cranks, wherein one crank-connecting rod mechanism drives the compressor piston, or drives the vertically stacked two-stage compressor piston, and the other two crank-connecting rod mechanisms drive two expander pistons respectively. That is, the three cranks are in the same plane, the first crank and the third crank are in the same direction, and the second crank is in the opposite direction to the first crank and the third crank; wherein the first crank and the second crank drive the expander piston, or the second crank and the third crank drive the expander piston, and the remaining crank drives the compressor piston.

[0013] Furthermore, in the internal combustion engine that achieves decoupling of compression ratio and expansion ratio, the combustion chamber is spherical or quasi-spherical in shape, and is characterized in that the combustion chamber forms a completely sealed independent space through the closing of the combustion chamber intake valve and the jet valve, and the combustion of the mixture in the combustion chamber is constant volume combustion or partial constant volume combustion.

[0014] Furthermore, the internal combustion engine that achieves decoupling of compression ratio and expansion ratio is characterized in that the cylinders can be combined to form an internal combustion engine with a greater number of in-line cylinders, stacked compression cylinders, V-shaped cylinders or horizontally opposed cylinders.

[0015] Furthermore, the internal combustion engine that achieves decoupling of compression ratio and expansion ratio is characterized in that any one, several or all of the compressor intake valve, compressor exhaust valve, combustion chamber intake valve, jet valve, and expander exhaust valve are driven by cam and / or jointly driven by hydraulic and solenoid valves; wherein the compressor intake valve and compressor exhaust valve can also adopt a check valve structure driven by gas pressure.

[0016] Furthermore, the internal combustion engine that achieves decoupling of compression ratio and expansion ratio is characterized in that the fuel of the internal combustion engine can be all ignitable liquid and / or ignitable gaseous fuels, especially hydrogen fuel.

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

[0018] (1) The intercooler reduces compression work and improves the efficiency of the internal combustion engine;

[0019] (2) The intercooler reduces the gas volume, achieves an ultra-high expansion ratio, and improves expansion efficiency;

[0020] (3) Due to independent combustion, high EGR rate and low temperature combustion technology can be achieved to reduce heat loss;

[0021] (4) Smaller combustion chamber, faster combustion and enhanced resistance to knock;

[0022] (5) Smaller engine size, especially three-cylinder engines, makes installation on vehicles easier;

[0023] (6) High efficiency output over the entire MAP range.

[0024] In short, this is a high-efficiency internal combustion engine with excellent thermodynamic properties such as nearly isothermal compression, constant volume combustion, low compression ratio, ultra-high expansion ratio, and low-temperature combustion. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 and Figure 2 It is a schematic diagram of the operating principle of the in-line three-cylinder internal combustion engine of the present invention.

[0026] Figure 3 and Figure 4 It is a schematic diagram of the operating principle of the inline four-cylinder internal combustion engine of the present invention.

[0027] Figure 5 It is a schematic diagram of the operating principle of the four-cylinder internal combustion engine with stacked two-stage compression cylinders according to the present invention.

[0028] Figure 6 It is a schematic diagram of the operating principle of the six-cylinder internal combustion engine with stacked two-stage compression cylinders according to the present invention.

[0029] Figure 7 The present invention Figure 1 and Figure 3 The schematic diagram of dynamic balancing of a three-crank crankshaft of an internal combustion engine is shown.

[0030] Figure 8 The present invention Figure 2 and Figure 4 The schematic diagram of dynamic balancing of a four-crank crankshaft of an internal combustion engine is shown. DETAILED DESCRIPTION

[0031] The following will be combined with the attached Figures 1 to 8 The technical solution of the present invention is described in detail.

[0032] The invention proposes a new thermodynamic cycle of an internal combustion engine that realizes decoupling of compression ratio and expansion ratio. There is no existing computational simulation software on the market. Therefore, the research team independently developed "a performance simulation and parameter optimization software for an internal combustion engine system that realizes decoupling of compression ratio and expansion ratio" and filed a computer software copyright application (serial number: 2024R11L2731550). After optimization and simulation calculations using the software, it is proved that the thermodynamic processes such as approximate isothermal compression, constant volume combustion, low temperature combustion and approximate adiabatic expansion are very excellent. After decoupling of compression ratio and expansion ratio, under the condition of compression ratio of 10:1, its expansion ratio can reach more than 30:1, which greatly improves the expansion work efficiency. In addition, this internal combustion engine with constant volume combustion mode also has a strong ability to resist combustion knock. Even if hydrogen combustion produces extremely high pressure and pressure rise rate, the combustion chamber can effectively resist its high pressure without being destroyed because high-strength materials can be used.

[0033] This technology enables the efficiency of existing gasoline engines to surpass or approach that of diesel engines, contributing to the reduction of carbon emissions. At the same time, it provides a technical approach for using hydrogen internal combustion engines in addition to hydrogen fuel cells, a carbon-neutral fuel.

[0034] Embodiment 1:

[0035] Figure 1 and Figure 2It is a schematic diagram of the operation of an in-line three-cylinder internal combustion engine that realizes the decoupling of compression ratio and expansion ratio. The internal combustion engine has three in-line cylinders, including a compressor cylinder 1 and two parallel expander cylinders 31, forming a compressor and two expander systems. The compressor C is connected to the expanders E1 and E2 through pipelines and valves. When the valve is closed, the compressor C and the expanders E1 and E2 are isolated from each other, forming an intake and compression stroke that is independently completed in the compressor cylinder 1, while the expansion and exhaust strokes are independently completed in the expanders E1 and E2. An intercooler 8 is arranged between the compressor C and the expanders E1 and E2, and a combustion chamber is arranged between the intercooler 8 and the two expansion cylinders 31. The crankshaft of the internal combustion engine has three cranks, which respectively drive a compressor piston and two expander pistons to reciprocate.

[0036] The volume of the compressor cylinder 1 is equal to or unequal to the volume of the expander cylinder 31 .

[0037] Specifically, it includes a compressor cylinder 1, a compressor piston 2, a compressor intake valve 3, a compressor intake passage 4, a compressor exhaust valve 5, a compressor exhaust pipe 6, an intercooler 8, an air storage tank 9, a compression chamber clearance volume V1, an expander cylinder 31, an expander piston 32, a combustion chamber intake valve 33, a combustion chamber intake pipe 34, an expander exhaust valve 35, an expander exhaust passage 36, a spark plug 37, a combustion chamber 38, a jet channel 39, a fuel injector 40, a jet valve 41, a second expander intake pipe 42 and an expansion chamber clearance volume V2;

[0038] Wherein: each expander cylinder 31 corresponds to a combustion chamber 38, and the charge of the internal combustion engine entering the intercooler 8 from the compressor cylinder 1 is equal to the sum of the charges entering the two combustion chambers 38 from the intercooler 8;

[0039] See Figure 1 a and Figure 2 a. As the crankshaft rotates, the compressor piston 2 moves downward from the top dead center, the compressor intake valve 3 opens, and air or a certain proportion of cooled EGR gas enters the compressor cylinder 1 through the compressor intake passage 4. Then the compressor piston 2 moves upward from its bottom dead center, and the gas entering the compressor cylinder 1 is compressed until the gas pressure in the compressor cylinder 1 is greater than / equal to the gas pressure in the intercooler 8. The compressor exhaust valve 5 opens, and the compressed gas enters the intercooler 8 through the compressor exhaust pipe 6. When the compressor piston 2 reaches its top dead center, the compressor exhaust valve 5 is closed, completing the intake and compression of the compressor. This is the intake stroke and compression stroke of the inline three-cylinder internal combustion engine.

[0040] in, Figure 1a shows that the piston of compressor C reaches its bottom dead center, completing the intake stroke of the compressor. Figure 2 a shows the process in which the piston of compressor C reaches its top dead center, completes its compression stroke and exhausts gas to cooler 8.

[0041] The compressed gas with a certain high temperature and pressure after compression is cooled in the intercooler 8, and the cooled gas is sent to the gas storage tank 9 to store and stabilize the pressure of the gas, completing the cooling process of the compressed gas. This process reduces the temperature and pressure of the compressed gas and reduces the volume of the gas, which not only reduces the compression work, but also lays a foundation for reducing the excessive temperature and pressure after combustion, and also reduces the volume of the combustion chamber 38 and increases the expansion ratio. This is the cooling process of the inline three-cylinder internal combustion engine.

[0042] When the expander piston 32 is near the bottom dead center, the combustion chamber jet valve 41 is closed to cut off the connection between the combustion chamber 38 and the expander cylinder 31, and at the same time, the combustion chamber intake valve 33 is opened to send the cooled gas stored in the gas storage tank 9 into the combustion chamber 38 through the combustion chamber intake pipe 34. At the same time, the fuel injector 40 injects fuel into the combustion chamber 38 or the inlet end of the combustion chamber intake valve 33, so that the gas entering the combustion chamber 38 and the fuel injected by the fuel injector 40 are fully mixed. The combustion chamber intake valve 33 is arranged at an appropriate position in the combustion chamber 38, which allows the gas to have sufficient turbulent kinetic energy after entering the combustion chamber 38, so that the mixed gas is accelerated to mix. Subsequently, the combustion chamber intake valve 33 is closed to form an independent closed space in the combustion chamber 38. Then, at an appropriate time during the movement of the expander piston 32 from its bottom dead center to its top dead center, the spark plug 37 arranged in the combustion chamber 38 ignites the mixed gas in the combustion chamber, so that the mixed gas in the combustion chamber 38 burns and produces high-temperature and high-pressure gas. This is the mixed gas formation and combustion process of the inline three-cylinder internal combustion engine.

[0043] The combustion is a typical constant volume combustion completed in a closed space, which has higher efficiency, higher temperature and higher pressure than other forms of combustion, and improves the ability of gas expansion to do work.

[0044] In order to ensure that the combustion temperature and pressure are not too high so as not to damage the mechanism of the internal combustion engine, the constant volume of combustion in the combustion chamber 38 can be reduced, that is: the jet valve 41 is opened early to allow a small amount of unburned mixture to be sprayed into the expander cylinder 31 for further combustion, which can greatly reduce the pressure in the combustion chamber 38 and the expander cylinder 41; or an appropriate proportion of cooling EGR is added to the mixture to greatly reduce the temperature and pressure in the combustion chamber 38 and the expander cylinder 41. A large EGR rate forms a low-temperature combustion mode, reducing external heat loss. This is a more suitable choice.

[0045] Regardless of the EGR rate and the combustion speed, the moment when the mixture is completely burned is determined to be the top dead center position of the expander piston 32 by calibrating the ignition advance angle.

[0046] Figure 1 b shows that the expander piston 32 of the internal combustion engine reaches its top dead center, at which time the combustion chamber 38 completes the intake, mixture formation, ignition and combustion processes, and the gas temperature and pressure in the combustion chamber reach the highest.

[0047] As the expander piston 32 moves upward from its lower dead center to a position near its upper dead center, the jet valve 41 is opened, and the high-temperature and high-pressure gas that has completed combustion is injected into the expansion chamber clearance volume V2 through the jet channel 39, and expands and performs work in the expander cylinder 31 at the highest expansion ratio.

[0048] Figure 2 b shows that the expansion piston 32 of the expander E1 reaches its bottom dead center. When the expander piston 32 reaches the vicinity of its bottom dead center, the expander exhaust valve 35 is opened, and as the expander piston 32 moves upward, the exhaust gas after combustion is discharged from the expander cylinder 31 through the expander exhaust passage 36. When the expander piston 32 reaches or approaches its top dead center, the expander exhaust valve 35 is closed, ready to enter the next cycle.

[0049] Figure 1 b shows that the expansion piston 32 has just reached its top dead center, completing its exhaust stroke.

[0050] This is the expansion stroke and exhaust stroke of an expander of an inline three-cylinder internal combustion engine. The expansion stroke and exhaust stroke of the second expander connected in parallel are exactly the same as the above expander, only the operating phase is different by 180 degrees of crankshaft angle, see Figure 1 c and Figure 2 c.

[0051] The inline three-cylinder internal combustion engine is composed of an intake stroke, a compression stroke, a cooling process, and two parallel combustion processes, an expansion stroke and an exhaust stroke of a compressor cylinder, forming a complete thermodynamic cycle and completing it in a 360-degree rotation of the same crankshaft.

[0052] The optimization data of Example 1 was obtained by simulation calculation using our self-developed "performance simulation and parameter optimization software for an internal combustion engine system that realizes decoupling of compression ratio and expansion ratio".

[0053] The optimized conditions are:

[0054] a. The higher the efficiency, the better, but the pressure, temperature, etc. must not exceed the limit.

[0055] b. The compressor is a single-stage compressor with a pressure ratio of: working pressure / intake pressure = 25.8 bar / 3 bar = 8.6. The single-stage pressure ratio limit shall not exceed 10.

[0056] c. With reference to the pressure that the expansion cylinder can withstand, the maximum pressure limit entering the expansion chamber after combustion shall not exceed 250 bar. The lower the better while ensuring efficiency.

[0057] d. The average temperature of the expansion cylinder shall not exceed 1150K.

[0058] e. The internal combustion engine speed is set to 3500RPM.

[0059] f. The compression cylinder volume, expansion cylinder volume and combustion chamber volume are selected according to the above conditions.

[0060] This embodiment sets the parameters when the length and height of the internal combustion engine are equal to those of a 1.5T internal combustion engine. Similarly, it is also a supercharged internal combustion engine. Observing Table 1, it is found that the maximum effective thermal efficiency is 52.6%, and the maximum effective power is 83.8Kw.

[0061] Table 1:

[0062]

[0063]

[0064] Embodiment 2:

[0065] Figure 3 and Figure 4 The schematic diagram of the operation of an inline four-cylinder internal combustion engine that realizes the decoupling of compression ratio and expansion ratio is shown. The internal combustion engine has four inline cylinders, including a first-stage compressor cylinder 11 and a second-stage compressor cylinder 21 connected in series, and two expander cylinders 31 connected in parallel, forming a two-stage compressor and two expander systems. The first-stage compressor cylinder 11 and the second-stage compressor cylinder 21 are in parallel. The first-stage compressor cylinder 11 and the second-stage compressor cylinder 21 are connected through pipelines and valves, and the second-stage compressor cylinder 21 and the expanders E1 and E2 are connected through pipelines and valves. When the valve is closed, the first-stage compressor cylinder 11, the second-stage compressor cylinder 21, the expanders E1 and E2 are isolated from each other, forming an intake and compression stroke that is completed in the first-stage compressor cylinder 11 and the second-stage compressor cylinder 21, respectively, while the expansion and exhaust strokes are completed independently in the expanders E1 and E2, respectively.

[0066] The crankshaft of the internal combustion engine has four cranks, which respectively drive two compressor pistons and two expander pistons to make them reciprocate.

[0067] The volume of the first-stage compressor cylinder 11 is equal to or unequal to the volume of the expander cylinder 31 .

[0068] Specifically, it includes a first-stage compressor cylinder 11, a first-stage compressor piston 12, a first-stage compressor intake valve 13, a first-stage compressor intake duct 14, a first-stage compressor exhaust valve 15, a first-stage compressor exhaust pipe 16, a first-stage intercooler 18, a first-stage air storage tank 19, and a first-stage compression chamber clearance volume V 11 , secondary compressor cylinder 21, secondary compressor piston 22, secondary compressor intake valve 23, secondary compressor intake duct 24, secondary compressor exhaust valve 25, secondary compressor exhaust pipe 26, secondary intercooler 28, secondary air storage tank 29, secondary compression chamber clearance volume V 12 , an expander cylinder 31, an expander piston 32, a combustion chamber intake valve 33, a combustion chamber intake pipe 34, an expander exhaust valve 35, an expander exhaust passage 36, a spark plug 37, a combustion chamber 38, a jet passage 39, a fuel injector 40, a jet valve 41, a second expander intake pipe 42 and an expansion chamber clearance volume V2;

[0069] Wherein: each expander cylinder 31 corresponds to a combustion chamber 38, and the charge of the internal combustion engine entering the primary intercooler 18 from the primary compressor cylinder 11 is equal to the charge entering the secondary compressor cylinder 21 from the primary intercooler 18; the charge of the internal combustion engine entering the secondary intercooler 28 from the secondary compressor cylinder 21 is equal to the sum of the charges entering the combustion chambers 38 of the two parallel expanders from the secondary intercooler (28);

[0070] See Figure 3 a and Figure 4 a. With the rotation of the crankshaft, the first-stage compressor piston 12 moves downward from the top dead center, the first-stage compressor intake valve 13 opens, and air or a certain proportion of cooled EGR gas enters the first-stage compressor cylinder 11 through the first-stage compressor intake passage 14. Then, the first-stage compressor piston 12 moves upward from its bottom dead center, and the gas entering the first-stage compressor cylinder 11 is compressed until the gas pressure in the first-stage compressor cylinder 11 is greater than / equal to the gas pressure in the first-stage intercooler 18. The first-stage compressor exhaust valve 15 opens, and the compressed gas enters the first-stage intercooler 18 through the first-stage compressor exhaust pipe 16. When the first-stage compressor piston 12 reaches its top dead center, the first-stage compressor exhaust valve 15 is closed, completing the intake and compression of the first-stage compressor. This is the first-stage intake stroke and the first-stage compression stroke of the inline four-cylinder internal combustion engine.

[0071] in, Figure 3 a shows that the first stage compressor piston 12 reaches its bottom dead center, completing the intake stroke of the first stage compressor. Figure 4a shows the process in which the first-stage compressor piston 12 reaches its top dead center, completes its first-stage compression stroke, and exhausts air to the cooler 18.

[0072] After the first-stage compression, the compressed gas with a certain high temperature and high pressure is cooled in the first-stage intercooler 18, and the cooled gas is sent to the first-stage gas storage tank 19 to store and stabilize the pressure of the gas, thereby completing the cooling of the compressed gas. This is the first cooling process of the inline four-cylinder internal combustion engine.

[0073] See Figure 3 b and Figure 4 b. As the crankshaft rotates further, the secondary compressor piston 22 moves downward from the top dead center, the secondary compressor intake valve 23 opens, and the gas stored in the primary air storage tank 19 enters the secondary compressor cylinder 21 through the secondary compressor intake passage 24. Then, the secondary compressor piston 22 moves upward from its bottom dead center, and the gas entering the secondary compressor cylinder 21 is further compressed until the gas pressure in the secondary compressor cylinder 21 is greater than / equal to the gas pressure in the secondary intercooler 28. The secondary compressor exhaust valve 25 opens, and the compressed gas enters the secondary intercooler 28 through the secondary compressor exhaust pipe 26. When the secondary compressor piston 22 reaches its top dead center, the secondary compressor exhaust valve 25 is closed, completing the intake and compression of the secondary compressor. This is the secondary intake stroke and secondary compression stroke of the inline four-cylinder internal combustion engine.

[0074] in, Figure 3 b shows that the piston 22 of the secondary compressor reaches its bottom dead center, completing the intake stroke of the secondary compressor. Figure 4 b shows the process in which the secondary compressor piston 22 reaches its top dead center, completes its compression stroke and exhausts gas to the cooler 28 .

[0075] The compressed gas with a certain high temperature and high pressure after the secondary compression is cooled in the secondary intercooler 28, and the cooled gas is sent to the secondary gas storage tank 29 to store and stabilize the pressure of the gas, completing the second cooling process of the compressed gas.

[0076] The two cooling processes reduce the temperature and pressure of the compressed gas and further reduce the volume of the gas, which not only reduces the compression work, laying the foundation for reducing the excessive temperature and pressure after combustion, but also reduces the volume of the combustion chamber 38 and lays the foundation for increasing the expansion ratio. This is the cooling process of the inline four-cylinder internal combustion engine.

[0077] Obviously, two compressions and two coolings save about 15% of compression work compared to one compression and one cooling, and also reduce about 15% of the heat discharged to the outside due to intermediate cooling during one compression and cooling process. On the one hand, it saves compression work, and on the other hand, it reduces the heat discharged to the outside, achieving double benefits, which is one of the reasons why the efficiency of this thermodynamic cycle can be improved.

[0078] See Figure 3 c and Figure 4 c. When the expander piston 32 is near the bottom dead center, the combustion chamber jet valve 41 is closed to cut off the connection between the combustion chamber 38 and the expander cylinder 31, and at the same time, the combustion chamber intake valve 33 is opened to send the cooled gas stored in the gas storage tank 29 into the combustion chamber 38 through the combustion chamber intake pipe 34. At the same time, the fuel injector 40 injects the fuel into the combustion chamber 38 or into the inlet end of the combustion chamber intake valve 33, so that the gas entering the combustion chamber 38 and the fuel injected by the fuel injector 40 are fully mixed. The combustion chamber intake valve 33 is arranged at an appropriate position in the combustion chamber 38, which allows the gas to have sufficient turbulent kinetic energy after entering the combustion chamber 38, so that the mixed gas is accelerated to mix. Subsequently, the combustion chamber intake valve 33 is closed to form an independent closed space in the combustion chamber 38. Then, at an appropriate time during the movement of the expander piston 32 from its bottom dead center to its top dead center, the spark plug 37 arranged in the combustion chamber 38 ignites the mixed gas in the combustion chamber, so that the mixed gas in the combustion chamber 38 burns and produces high-temperature and high-pressure gas. This is the mixed gas formation and combustion process of the inline four-cylinder internal combustion engine.

[0079] The combustion is a typical constant volume combustion completed in a closed space, which has higher efficiency, higher temperature and higher pressure than other forms of combustion, and improves the ability of gas to expand and do work.

[0080] Regardless of the EGR rate and the combustion speed, the moment when the mixture is completely burned is determined to be the top dead center position of the expander piston 32 by calibrating the ignition advance angle.

[0081] in, Figure 3 c shows that the combustion chamber 38 of the expander E1 has completed combustion, the expander piston 32 has just reached its top dead center, and the jet valve 40 is about to open or has just opened.

[0082] In order to ensure that the combustion temperature and pressure are not too high so as not to damage the mechanism of the internal combustion engine, the constant volume of combustion in the combustion chamber 38 can be reduced, that is, the jet valve 41 is opened early to allow a small amount of unburned mixed gas to be sprayed into the expander cylinder 31 for further combustion, which can greatly reduce the pressure in the combustion chamber 38 and the expander cylinder 41. That is, after the duration CA0-CA100 required for the complete combustion of the mixed gas is calibrated and measured, the ignition advance angle is determined to be less than the duration, so that a very small part of the mixed gas that has not yet completed combustion can enter the expansion chamber V2 for further combustion.

[0083] Alternatively, adding an appropriate proportion of cooled EGR to the mixture can greatly reduce the temperature and pressure in the combustion chamber 38 and the expander cylinder 41, which is a more appropriate option.

[0084] It should be noted that when the EGR rate rises to a certain extent, such as above 30%, the ignition and combustion of the Otto cycle internal combustion engine become very difficult. Due to the extension of the combustion duration, the moment when the complete combustion is completed has reached 50 to 60 crank angles after the top dead center or even more. At this time, the piston moves downward too much, resulting in a large decrease in the temperature in the cylinder, which further extends the combustion duration, so that a small part of the mixture cannot be burned, or even if it is burned, the combustion center of gravity of the internal combustion engine is greatly moved backward, resulting in a decrease in the effective expansion ratio, and ultimately reducing the efficiency of the Otto cycle internal combustion engine.

[0085] On the contrary, the combustion mode provided by this technology is constant volume combustion. During the combustion process, the gas temperature and pressure become higher and higher. There is no Otto cycle combustion degradation as the EGR rate increases. Therefore, this constant volume combustion mode has the ability to adopt a higher EGR rate.

[0086] As the expander piston 32 moves upward from its lower dead center to a position near its upper dead center, the jet valve 41 is opened, and the high-temperature and high-pressure gas that has completed combustion is injected into the expansion chamber clearance volume V2 through the jet channel 39, and expands and performs work in the expander cylinder 31 at the highest expansion ratio.

[0087] When the expander piston 32 reaches the vicinity of its lower dead center, the expander exhaust valve 35 is opened. As the expander piston 32 moves upward, the exhaust gas after combustion is discharged from the expander cylinder 31 through the expander exhaust duct 36. When the expander piston 32 reaches or approaches its upper dead center, the expander exhaust valve 35 is closed, preparing to enter the next cycle.

[0088] in, Figure 4 c shows that the expansion work of the expander E1 has been completed, the expander piston 32 has just reached its bottom dead center, the jet valve 40 has just been closed, and the expander exhaust valve 35 has just been opened.

[0089] This is the expansion stroke and exhaust stroke of an expander of an inline four-cylinder internal combustion engine. The expansion stroke and exhaust stroke of the second expander connected in parallel are exactly the same as the process of the above expander, with only a difference of 180 crankshaft angles in the operating phase.

[0090] Figure 3 d and Figure 4 d shows the operation process of expander E2.

[0091] The inline four-cylinder internal combustion engine is composed of two series-connected intake strokes, compression strokes and cooling processes, and two parallel-connected combustion processes, expansion strokes and exhaust strokes, forming a complete thermodynamic cycle and completing it in a 360-degree rotation of the same crankshaft.

[0092] The optimization data of Example 2 was obtained by simulation calculation using our self-developed "performance simulation and parameter optimization software for an internal combustion engine system that realizes decoupling of compression ratio and expansion ratio".

[0093] The optimized conditions are:

[0094] a. The higher the efficiency, the better, but the pressure, temperature, etc. must not exceed the limit.

[0095] b. The compressor is a two-stage compressor. The two cylinders of the two-stage compressor are arranged in parallel. The pressure ratio is: working pressure /

[0096] Inlet pressure = 24.7bar / 1bar = 24.7, and its single-stage pressure ratio is 4.97, which does not exceed the limit of 10.

[0097] c. Referring to the pressure that the expansion cylinder can withstand, the maximum pressure entering the expansion chamber after combustion is

[0098] 147.8bar, does not exceed the limit of 250bar. The lower the better while ensuring efficiency.

[0099] d. The average temperature of the expansion cylinder shall not exceed 1150K.

[0100] e. The internal combustion engine speed is set to 3500RPM.

[0101] f. The compression cylinder volume, expansion cylinder volume and combustion chamber volume are selected according to the above conditions.

[0102] This embodiment 2 is a set parameter when the length and height of the internal combustion engine are equal to those of the 1.5L internal combustion engine. Similarly, it is also a non-supercharged internal combustion engine. Observing Table 2, it is found that the maximum effective thermal efficiency is 51.5%, and the maximum effective power is 38.4Kw. This configuration of the combustion chamber volume, the first compression cylinder volume, the expansion cylinder volume and the EGR rate makes the power larger, but the efficiency is slightly lower than that of other embodiments.

[0103] Table 2:

[0104]

[0105]

[0106] A variation of Embodiment 2 adopts a four-cylinder in-line naturally aspirated form, wherein the volume of the first-stage compression cylinder is equal to the volume of the two expansion cylinders, and the second-stage compression cylinder is ranked at the first crank, the first-stage compression cylinder is ranked at the second crank, and the two expansion cylinders are ranked at the third and fourth cranks. The combustion chamber volume size, the first and second compression cylinder volumes, the expansion cylinder volume, and the external EGR value in the second embodiment are modified, and the length and height dimensions of the internal combustion engine are kept the same as those of the Otto cycle internal combustion engine 1.5L internal combustion engine. The results after optimization calculation are shown in Table 3.

[0107] Comparing Table 3 with Table 2, except for the power which is smaller than that in Table 2, all other indicators in Table 3 are better than those in Table 2. The indicated efficiency is as high as 53.5%, the effective efficiency is as high as 50%, and the maximum expansion cylinder pressure is 146.6 bar, which is lower than the maximum pressure of 164.1 bar in Table 2. The pressure reduction is beneficial to the strength and NVH of the internal combustion engine. The EGR rate is 20%, which is lower than 32% in Table 2, which indicates that it is easier to ignite successfully during operation. The expansion ratio is 36.8:1, which is much larger than the expansion ratio of 26.4:1 in Table 2, which is also the reason why the efficiency is higher than that in Table 2.

[0108] Another variation of Example 2, the size of the internal combustion engine is the same as that in Table 3, and a supercharger is added to increase the power and expand the combustion chamber volume. The results are listed in Table 4. Observing Table 4, the maximum expansion cylinder pressure reaches 201.8 bar, which is still lower than the maximum pressure of the diesel engine. If the maximum pressure is controlled at around 160 bar, it is only necessary to adjust the boost pressure to 1.8 bar.

[0109] The main purpose of the above two variations of Embodiment 2 is to configure a naturally aspirated and a supercharged internal combustion engine to run on the same structure, and to provide high power and low power options to simplify processing.

[0110] Table 3:

[0111]

[0112]

[0113] Table 4:

[0114]

[0115]

[0116] Embodiment 3:

[0117] Figure 5 The schematic diagram of the operating principle of a four-cylinder internal combustion engine with two-stage compression cylinders stacked to achieve decoupling of compression ratio and expansion ratio. It includes a first-stage compressor cylinder 11 and a second-stage compressor cylinder 21 connected in series therewith, and two expander cylinders 31. The second-stage compressor cylinder 21 is placed on the first-stage compressor cylinder 11 to form a vertical stacked structure. The crankshaft of the internal combustion engine has three cranks, one of which drives the stacked two-stage compressor piston, and the other two cranks drive two expander pistons respectively to make them reciprocate.

[0118] The operating principle and operating process of the four-cylinder internal combustion engine, including the intake stroke, compression stroke, intermediate cooling process, combustion process, expansion stroke and exhaust stroke are the same as those in Example 2, except that the installation position and driving mechanism of the two-stage compressor are different.

[0119] The special feature of this structure is that, although there are four cylinders, it only occupies the longitudinal length of three cylinders. Therefore, with the same efficiency and power, the length of the internal combustion engine can be significantly reduced.

[0120] The data after optimization of Example 3 are listed in the table below. The optimization conditions are basically the same as those of Example 2, except that the two compression cylinders are stacked to save space. Therefore, under the same length and height as a 1.5L internal combustion engine, the compressor cylinder volume and the expansion cylinder volume are both increased. Therefore, under the condition of roughly the same efficiency, the power is greater and the pressure of the expansion cylinder is lower, which is beneficial to improving the reliability of the internal combustion engine. Of course, the NVH performance of the internal combustion engine will also be better.

[0121] From observation of Table 5, it can be seen that the maximum indicated efficiency is 52.8% and the maximum indicated power is 45.2Kw.

[0122] Table 5:

[0123]

[0124]

[0125] Obviously, Example 3 is worthy of promotion, and it has low cost, high power, high efficiency, and small size, and all its advantages are fully demonstrated.

[0126] Note: The parameters of Table 2, Table 3 and Table 4 of Example 2 and its variants are also applicable to Example 3. Since the size of Example 3 is three crank mechanisms, the length of the internal combustion engine of Example 3 is generally reduced, which is the biggest advantage.

[0127] Example 4, that is, its operating principle diagram is the same as that of Example 3 Figure 5 This embodiment only determines that the effective power of the internal combustion engine is 25Kw, and obtains the smallest installation size, which is particularly important for use as a range extender.

[0128] The data after optimization of Example 4 are listed in the table below. The optimization conditions are basically the same as those of Example 2, except that the two compression cylinders are stacked to save space.

[0129] Observe the following table and you will find that the compression cylinder capacity of the internal combustion engine is 218cc, the two expansion cylinder capacities are 218cc, the supercharger boost pressure is 2bar, the maximum expansion cylinder pressure is 199.3bar, the maximum indicated efficiency is 53.9%, the maximum effective efficiency is 52.4%, the maximum indicated power is 27.3Kw, and its effective power is 25Kw.

[0130] Although the expansion cylinder pressure is relatively high, the efficiency is also significantly improved, and its maximum pressure still does not reach the level of a diesel engine. In particular, the cylinder volume is very small, and the total pressure borne by the connecting rod crank mechanism is not very high. Since the cylinder volume is very small, the length of the internal combustion engine is reduced by about 130mm compared to the 1.5T Otto cycle internal combustion engine, and its height is reduced by about 45mm, which is a very good choice as a range extender.

[0131] Table 6:

[0132]

[0133]

[0134] Embodiment 5:

[0135] Figure 6 The schematic diagram of the operating principle of a six-cylinder internal combustion engine with two-stage compression cylinders stacked to achieve decoupling of compression ratio and expansion ratio. It includes four cylinders forming two groups of stacked two-stage compressors, and the remaining two cylinders are used as two expander cylinders. The crankshaft of the internal combustion engine has four cranks, two of which drive two stacked two-stage compressor pistons respectively, and the other two cranks drive two expander pistons to make them reciprocate.

[0136] The operating principle and operating process of the six-cylinder internal combustion engine with two two-stage compressors, including the intake stroke, compression stroke, intermediate cooling process, combustion process, expansion stroke and exhaust stroke are the same as those of a four-cylinder internal combustion engine for decoupling the compression ratio and the expansion ratio described in Example 2, except that the two single-stage compressors are replaced by two two-stage compressors.

[0137] After optimizing Example 5, the data are listed in Table 7. The optimized conditions are basically the same as those of Example 2, except that the four compression cylinders are stacked in pairs to form two two-stage compressors. Under the same length and height as the 1.5L internal combustion engine, the cylinder volume of the first-stage compressor is 300cc, and the expansion cylinder volume is 375cc. This structure does not seem to save installation space, and the two-stage compressor increases the cost, which is not the best choice.

[0138] From observation of Table 7, we can see that the maximum indicated efficiency is 51.9%, the maximum indicated power is 33.6Kw, and the maximum pressure of the expansion cylinder is 141.5bar.

[0139] Table 7:

[0140]

[0141]

[0142] Embodiment 6:

[0143] An embodiment of the dynamic balancing principle of a three-crank flat crankshaft.

[0144] Figure 7 This is a schematic diagram of a three-crank flat crankshaft dynamic balance.

[0145] The internal combustion engine for realizing decoupling of compression ratio and expansion ratio as described in claim 1 and claim 3 is characterized in that the crankshaft has three cranks, and the three cranks are all in the same plane. One crank is used to drive the piston of a single-stage compressor or the piston of a two-stage compressor, and the two cranks are used to drive the two expander pistons to make them reciprocate.

[0146] Figure 7 As shown, the reciprocating inertia forces of the first and third piston-connecting rod crank mechanisms are F1 and F3, which are in the upward direction, and the reciprocating inertia force of the second piston-connecting rod crank mechanism is F2, which is in the downward direction. The sum of the reciprocating inertia forces ∑F generated by them is zero, that is: F1+F3=F2, and the sum of the reciprocating inertia moments ∑M is zero. That is: F1*L1=F3*L2.

[0147] Assume that M1, M2 and M3 are the reciprocating inertia masses of the three cylinders, R1 is the crank radius driving the compressor piston, R2 is the crank radius driving the two expander pistons, λ1 is the compressor connecting rod ratio, λ2 is the expander connecting rod ratio. L1 is the center distance from the compression cylinder to the adjacent expansion cylinder, and L2 is the center distance between the two expansion cylinders. Then:

[0148] F1=M1*R1*ω 2 *(cosα+λ1cos(2α)),

[0149] F2=M2*R2*ω 2 *(cosα+λ2cos(2α)),

[0150] F3=M3*R2*ω 2 *(cosα+λ2cos(2α)),

[0151] M1*R1*ω 2 *(cosα+λ1cos(2α))+M3*R2*ω 2 *(cosα+λ2cos(2α))

[0152] =M2*R2*ω 2 *(cosα+λ2cos(2α)),

[0153] M1*R1*(cosα+λ1cos(2α))+M3*R2*(cosα+λ2cos(2α))

[0154] =M2*R2*(cosα+λ2cos(2α)),

[0155] Assuming β is the crank proportional factor, then R1 = βR2, and the relationship between the compressor reciprocating inertia mass M1 and the expander reciprocating inertia mass M3, as well as the relationship between the two expander reciprocating inertia masses M2 and M3 is obtained:

[0156] M1=L2 / (L1*β)*M3,

[0157] M2=(L2+L1) / (L1)*M3.

[0158] When each reciprocating inertial mass satisfies the above relationship, the equilibrium condition can be achieved, which can be met by changing the size and material.

[0159] As for the rotational inertia force, it can be balanced by the crankshaft counterweight.

[0160] The above equilibrium state is more like the situation of an Otto cycle 4-cylinder internal combustion engine.

[0161] Embodiment 7:

[0162] The present technology provides an embodiment of the four-crank crankshaft dynamic balancing principle.

[0163] Figure 8 It is a schematic diagram of dynamic balancing of a four-crank crankshaft of an internal combustion engine of this technology.

[0164] Unlike the Otto cycle, after optimization using self-developed simulation software, it was found that due to the different volumes of the first-stage compression cylinder and the second-stage compression cylinder, the cylinder center distances are also different, so the reciprocating inertia forces formed by the four cranks are not equal. Therefore, it is necessary to determine the structural parameters of the internal combustion engine based on the optimized efficiency, power and other parameters, including the structural dimensions of the crankshaft and how to achieve dynamic balance.

[0165] The internal combustion engine that realizes decoupling of compression ratio and expansion ratio is characterized in that its crankshaft has four cranks, and the four cranks are all in the same plane. The first and fourth cranks face upward, and the second and third cranks face downward. The secondary compressor has a smaller volume and a shorter stroke, while the cylinder size of the primary compressor is larger, larger than the cylinder size of the expander. Regardless of the cylinder size, it is not very difficult to change the mass of the piston, connecting rod and crank of the primary and secondary compressors by changing the structure (such as using a ten-byte compressor structure) or changing the specific gravity of the material, so that the reciprocating inertia force and reciprocating inertia moment of the crankshaft are balanced.

[0166] For the convenience of description, the crankshaft flywheel end is set to be the fourth crank, wherein: the first crank is a two-stage compression cylinder, whose reciprocating inertia force is F1, the second crank is a one-stage compression cylinder, whose reciprocating inertia force is F2, the third crank and the fourth crank are two identical expansion cylinders, whose reciprocating inertia forces are F3 and F4.

[0167] Assume that the cylinder center distance from the first cylinder to the second cylinder is A, the cylinder center distance from the second cylinder to the third cylinder is B, and the cylinder center distance from the third cylinder to the fourth cylinder is C. According to the force balance and moment balance relationship:

[0168] The force balance is: F1+F4=F2+F3,

[0169] Torque balance: F1(A+B+C)=F2(B+C)+F3C,

[0170] Setting: F3=F4, then F1=F2;

[0171] F1A=F3C, then F1 / F3=C / A;

[0172] That is, when F1=F2, F3=F4, and F1 / F3=C / A, the crankshaft can achieve reciprocating inertia force balance and reciprocating inertia moment balance, and the balance of rotational inertia force is solved by the crankshaft balancing block.

[0173] In order to balance the output torque, the first and second cylinders of the four-cylinder internal combustion engine are used as expander cylinders, or the third and fourth cylinders are used as expander cylinders, and the timing phase difference between the two expander cylinders is 180 degrees, that is, one expander cylinder is ignited every 180 degrees, forming a relatively uniform output torque and reducing the NVH of the internal combustion engine.

[0174] Although the volumes of the two compressor cylinders are different, if an equal pressure ratio design is adopted, the work consumed by the two cylinders is almost equal. Therefore, the fluctuation effect on the rotational torque output is extremely small and can be ignored.

[0175] Based on the above reasons, the present invention adds the content that the cylinder capacity of each compressor is equal to or unequal to the cylinder capacity of the expander in the claims.

[0176] Other embodiments are that, through the above-mentioned embodiment of an internal combustion engine that realizes decoupling of compression ratio and expansion ratio, professionals in the field can easily combine it into an in-line, compression cylinder stacking, V-cylinder or horizontally opposed cylinder internal combustion engine with more cylinders.

[0177] An embodiment of the valve system driving mechanism is that any one or all of the jet valve, combustion chamber intake valve, compressor exhaust valve, compressor intake valve and expander exhaust valve are driven by a cam.

[0178] Alternatively, any one or all of the jet valve, combustion chamber intake valve, compressor exhaust valve, compressor intake valve and expander exhaust valve are driven jointly by hydraulic and solenoid valves.

[0179] The preferred embodiment of the compressor valve system drive mechanism is to use the same valve plate check valve driven by gas pressure as the existing air compressor. Especially in the case of two-stage compression, the use of the valve plate check valve can greatly reduce the product structure and cost, while increasing the reliability of the product.

[0180] An embodiment involving the installation position of the fuel injector 40 is that the fuel injector 40 sprays the fuel into the combustion chamber 38, and can also spray the fuel into the front end of the valve port of the expansion machine intake valve 33.

[0181] As an alternative embodiment of the fuel type, the internal combustion engine may be fueled by any liquid and / or gaseous ignitable fuel, in particular hydrogen fuel.

Claims

1. An internal combustion engine that realizes decoupling of compression ratio and expansion ratio, which is composed of at least one compressor and at least two expanders, wherein the compressor is a single-stage compressor composed of one cylinder, or a two-stage compressor composed of two cylinders, and the two expanders are composed of two parallel cylinders. Characterized in that: The number of the compressors and the number of the expanders are 1:2, and the cylinder capacity of the compressors is equal to or unequal to that of the expander; the compressor piston and the expander piston are driven by the same crankshaft to reciprocate between their respective top dead center and bottom dead center; an intercooler and a combustion chamber are sequentially arranged between the compressor cylinder and the expander cylinder of the internal combustion engine, each combustion chamber corresponds to an expander cylinder connected thereto, and they are connected by pipelines and valve systems; With the reciprocating motion of the compressor piston and the expander piston and the timing of the opening and closing of the valve system, the compressor cylinder completes the intake stroke and compression stroke of the internal combustion engine, the compressed gas is sent to the intercooler for cooling, and then sent to the combustion chamber for combustion, and the generated high-temperature and high-pressure gas is sprayed into the expander cylinder to complete the expansion stroke and exhaust stroke; The operation of the internal combustion engine consists of a complete thermodynamic cycle consisting of an intake stroke, a compression stroke, an intermediate cooling process, a combustion process, an expansion stroke and an exhaust stroke, and is completed by the same crankshaft in a 360-degree rotation.

2. An internal combustion engine for achieving decoupling of compression ratio and expansion ratio according to claim 1, characterized in that: The internal combustion engine has three in-line cylinders, including a compressor cylinder and two expander cylinders connected in parallel; the crankshaft of the internal combustion engine has three cranks, which respectively drive a compressor piston and two expander pistons to make them reciprocate.

3. An internal combustion engine for achieving decoupling of compression ratio and expansion ratio according to claim 1, characterized in that: The internal combustion engine has four in-line cylinders, wherein: two cylinders constitute a two-stage compressor, and the other two cylinders are parallel expander cylinders; the first-stage compressor cylinder, the second-stage compressor cylinder and the two expander cylinders of the two-stage compressor are arranged in parallel; the crankshaft of the internal combustion engine has four cranks, which respectively drive two compressor pistons and two expander pistons to make them reciprocate.

4. The internal combustion engine for achieving decoupling of compression ratio and expansion ratio according to claim 1, characterized in that: The internal combustion engine has four cylinders, wherein: two cylinders constitute a two-stage compressor, and the other two cylinders are parallel expander cylinders; wherein the second-stage cylinder of the two-stage compressor is placed on the first-stage compressor cylinder of the two-stage compressor to form a stacked structure; the crankshaft of the internal combustion engine has three cranks, which respectively drive a stacked two-stage compressor piston and two expander pistons to make them reciprocate.

5. An internal combustion engine that realizes decoupling of compression ratio and expansion ratio, characterized in that: The internal combustion engine has three cylinders, wherein: two cylinders constitute a two-stage compressor, and the other cylinder is an expander cylinder; the second-stage cylinder of the two-stage compressor is placed on the first-stage compressor cylinder of the two-stage compressor to form a stacked structure; the crankshaft of the internal combustion engine has two cranks, which respectively drive a stacked two-stage compressor piston and an expander piston to make them reciprocate.

6. An internal combustion engine for achieving decoupling of compression ratio and expansion ratio according to claim 2 or 4, characterized in that: The crankshaft has a planar crankshaft with three cranks, wherein one crank-connecting rod mechanism drives the compressor piston, or drives the stacked two-stage compressor piston, and the other two crank-connecting rod mechanisms drive two expander pistons respectively; that is, the three cranks are in the same plane, the first crank and the third crank are in the same direction, and the second crank is in the opposite direction to the first crank and the third crank; wherein the first crank and the second crank drive the expander piston, or the second crank and the third crank drive the expander piston, and the remaining crank drives the compressor piston.

7. An internal combustion engine that realizes decoupling of compression ratio and expansion ratio according to claims 1 and 5, wherein the combustion chamber is spherical or quasi-spherical in shape, characterized in that: The combustion chamber forms a completely sealed independent space by closing the combustion chamber intake valve and the jet valve, and the combustion of the mixed gas in the combustion chamber is constant volume combustion or partial constant volume combustion.

8. An internal combustion engine that realizes decoupling of compression ratio and expansion ratio according to claims 1 and 5, characterized in that: The cylinders can be combined to form an internal combustion engine with a larger number of in-line cylinders, compressed cylinder stacking, V-type cylinders or horizontally opposed cylinders.

9. An internal combustion engine that realizes decoupling of compression ratio and expansion ratio according to claims 1 and 5, characterized in that: Any one, several or all of the compressor intake valve, compressor exhaust valve, combustion chamber intake valve, jet valve, and expander exhaust valve are driven by cams and / or hydraulic and solenoid valves; wherein, the compressor intake valve and compressor exhaust valve can also adopt a check valve structure driven by gas pressure.

10. An internal combustion engine that realizes decoupling of compression ratio and expansion ratio according to claims 1 and 5, characterized in that: The fuel for the internal combustion engine is any ignitable liquid and / or ignitable gaseous fuel, in particular hydrogen fuel.

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