Fuel engine operation system structure integrating cooling compressed air and operation method of fuel engine operation system structure

Abstract

The invention discloses a fuel engine operation system structure integrating cooling compressed air and an operation method of the fuel engine operation system structure, and relates to the technical field of new energy and engines. Compressed air can efficiently and quickly store energy and is an energy carrier. The method comprises the following steps that S1, a compressed air tank is adopted as an air supply mechanism for cooling compressed air; s2, cooling compressed air is guided into an engine air cylinder in the early stage of an air inlet stroke or the late stage of a compression stroke, compression of the part of air in the compression stroke is reduced, the temperature of compressed mixed gas is reduced, the combustion temperature of the engine is reduced, engine knocking is reduced, the compression negative work of the engine is reduced, and the air inlet amount of the engine is increased; energy stored by compressed air is released in the expansion stroke to do positive work, the power and heat efficiency of the engine are improved, the NOx generation rate is reduced, and when the engine is in the lean-burn working condition, only a conventional emission aftertreatment system is needed to meet the emission regulation requirement; and S3, compressed air is provided by a multi-stage compressor.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy engines, and in particular to a fuel engine operating system structure integrating cooling compressed air and an operating method thereof. Background Art

[0002] Compressed air is a highly efficient energy storage medium. During the off-peak period of the power grid, a large amount of electricity needs to be stored in time, and wind power and solar power also need fast storage devices. Battery charging, raising the water level, and compressed air are all ways to store energy. Batteries charge slowly, and raising the water level is limited by the terrain. Compressed air is the most convenient way to store energy. The compressed air power device is a new energy device. The compressed air engine uses the expansion of compressed air in the cylinder to do work. The compressed air engine alone to drive the vehicle has low energy density and low efficiency. It will freeze if the temperature is too low in the later stage of expansion, and its practical value is not high.

[0003] The improvement of the thermal efficiency of fuel engines is greatly affected by knock and intake volume. Increasing the compression ratio is an effective way to improve the efficiency of fuel engines. The increase in the engine compression ratio is limited by the engine combustion knock. The main cause of engine knock is that the engine combustion temperature is too high. The increase in intake volume is affected by engine knock. Miller cycle and lean combustion can reduce the engine combustion temperature, reduce the engine knock tendency, allow a higher compression ratio, and thus improve engine efficiency. These measures will also reduce the effective power of the engine. The engine cylinder splitting technology completes the compression process outside the combustion chamber, which can theoretically prevent knock, allow a higher compression ratio, and improve the thermal efficiency of the engine.

[0004] Turbocharging uses the exhaust gas energy generated by the engine to drive the air compressor, increase the pressure of the engine intake, increase the engine intake volume, and thus increase the engine power. The pressurized air enters the cylinder from the engine intake valve, is compressed during the compression stroke, and the temperature rises. To prevent knocking, the compression ratio of a turbocharged engine is usually lower than that of a naturally aspirated engine.

[0005] In an engine that uses split-cylinder technology, the conversion of gas from the compression cylinder to the expansion cylinder occurs during the downward movement of the expansion piston. The ignition time occurs after this conversion, and the combustion time is too late. The high-temperature gas cannot fully do work, and the effective efficiency is not high. The ideal ignition time is about 20 degrees of crankshaft angle before the piston reaches the top dead center, and the highest pressure of the gas in the cylinder occurs about 10 degrees of crankshaft angle after the piston leaves the top dead center. This is something that split-cylinder technology cannot do. In practice, the efficiency of engines using split-cylinder technology does not exceed that of conventional engines.

[0006] Miller cycle engine uses early closing of intake valve, which reduces the effective compression ratio, while the engine expansion ratio remains unchanged. Reducing the effective compression ratio reduces the negative work done by the engine when the piston moves upward during the engine compression process. Large expansion ratio engines reduce the exhaust gas temperature at the end of expansion and reduce the heat carried away by the exhaust gas. Reducing the effective compression ratio also reduces the gas temperature at the end of compression, reduces the tendency of knock, and allows the design of a larger expansion ratio. In theory, the larger the ratio of expansion ratio to compression ratio, the higher the thermal efficiency of the engine. However, the reduction of effective compression ratio will reduce the engine intake time, thereby reducing the intake volume, reducing the effective work of the engine, and reducing the engine power. Turbocharging and Miller cycle can be used together to alleviate the power decline to a certain extent. However, the increase in compression end temperature limits the improvement of power and efficiency. If compressed air (at room temperature) participates in the engine intake process, the intake volume is greatly increased, and while increasing the engine power, the compression end temperature is further reduced, allowing a larger geometric compression ratio. The energy stored in compressed air is released during the engine work process, improving the engine power and efficiency. In theory, the geometric compression ratio of this engine is only limited by the processing and manufacturing process, and in theory the engine efficiency can be very high.

[0007] Lean burn technology is also an effective way to improve engine efficiency. Lean burn can reduce engine combustion temperature, reduce engine knock tendency, allow higher compression ratio, reduce exhaust temperature, reduce heat dissipation loss, and thus improve engine efficiency. Traditional lean burn engines generally use stratified combustion due to ignition energy limitations, and the fuel concentration is unevenly distributed in the cylinder. Near the spark plug, the fuel concentration is high, and ordinary spark plugs can ignite the air-fuel mixture. The efficiency of the three-way catalytic converter for emission post-treatment is very low in converting NOx emissions under lean burn conditions. Therefore, stratified lean burn engines need to add special post-treatment systems to treat NOx, such as SCR systems (ammonia catalytic reduction denitrification). SCR systems usually use urea as a denitrification agent. Urea is constantly consumed in this engine, and there is a smell of ammonia nearby. In order to avoid this complex post-treatment implementation and make the original NOx emissions of lean burn engines meet regulatory standards, ultra-lean homogeneous lean burn technology has been proposed. Ultra-lean means that the relative equivalent air-fuel ratio lambda is about 2. Calculated by mass, the corresponding gasoline air-fuel ratio is about 29:1, and the methanol air-fuel ratio is about 13:1. Ultra-lean combustion reduces the combustion temperature of the mixture and reduces NOx emissions. However, it is difficult to ignite an ultra-lean mixture. Various high-energy ignition technologies are being developed (such as spark plugs with 250mJ and greater ignition energy, plasma ignition, laser ignition, pre-combustion chamber ignition, etc.). Among them, the pre-combustion chamber has the highest ignition energy, which can ignite a mixture with a relative equivalent air-fuel ratio lambda greater than 2. The relative equivalent air-fuel ratio lambda in the pre-combustion chamber is close to the equivalent ratio of 1. The spark plug ignites the mixture in the pre-combustion chamber, and the temperature and pressure of the mixture in the pre-combustion chamber rise sharply. Under the huge pressure difference between the inside and outside of the pre-combustion chamber, the semi-burned mixture in the pre-combustion chamber is ejected from the spray hole to ignite the mixture in the main combustion chamber. At present, the effective thermal efficiency of ultra-lean homogeneous lean-burn engines exceeds 45%. Although the original NOx emissions are much less than those of stratified lean-burn engines, they still cannot meet emission regulations. The original NOx emissions are exponentially related to temperature. For every 100 degrees decrease in temperature, the original NOx emissions are reduced by about 6 times. Using compressed air at room temperature to reduce the intake temperature can make the original NOx emissions of ultra-lean-burn engines meet emission regulations.

[0008] The existing technology of injecting gas into the pre-combustion chamber aims to sweep out the residual exhaust gas in the pre-combustion chamber and increase the ignition energy of the pre-combustion chamber. The gas injected into the pre-combustion chamber is not cooled and has a high temperature. In addition, it is generally injected at the beginning of the compression stroke. The injected gas does negative work on the piston, reducing the effective thermal efficiency of the engine. The temperature of the gas in such a pre-combustion chamber is very high, which is the main source of NOx.

[0009] Therefore, we propose a fuel engine operating system structure and operating method that integrates cooling compressed air to solve the above-mentioned problems.

[0010] The above information disclosed in this background technology is only used to increase the understanding of the background technology of the present invention and therefore, it may include information that does not constitute the prior art known to ordinary technicians in this field. Summary of the invention

[0011] The object of the present invention is to provide a fuel engine operating system structure integrating cooling compressed air and an operating method thereof, so as to solve the problems raised by the above-mentioned background technology.

[0012] To achieve the above object, the present invention provides the following technical solution: a fuel engine operating system structure integrating cooling compressed air, comprising:

[0013] An engine body, wherein the engine body is provided with a main combustion chamber, a fuel injector and a spark plug are installed on the main combustion chamber, and an intake valve and an exhaust valve are correspondingly arranged on the main combustion chamber;

[0014] The air supply mechanism adopts a compressed air tank or a multi-stage compressor. The air supply mechanism is connected to a compressed air rail or an intake manifold through an air supply pipe, and supplies air to the engine through the compressed air rail or the intake manifold. The driving wheel of the multi-stage compressor is driven by a motor or an engine.

[0015] Preferably, the air supply mechanism uses a compressed air tank to supply air to the main combustion chamber of the engine, and the air supply pipe is provided with a primary pressure reducing valve, a secondary pressure reducing valve and an air flow meter.

[0016] Preferably, the compressed air enters the main combustion chamber of the engine through the intake manifold, the intake duct, and the intake valve; the intake valve is closed in the early stage of the intake stroke to reduce the compression of the compressed air in the compression stroke.

[0017] Preferably, the main combustion chamber is also equipped with a jet nozzle, which is connected to the compressed air rail. The jet nozzle is arranged so that the flow direction of the injected gas is consistent with the flow direction of the gas flowing into the intake valve; the main combustion chamber inhales air from the outside through the intake valve, and the compressed air is sprayed into the main combustion chamber through the jet nozzle; this reduces the demand for compressed air; the jet nozzle works in the early stage of the intake stroke, and the intake valve closing time must be after the jet nozzle stops working, and the specific time is determined by the engine calibration; the proportion of compressed air sprayed by the jet nozzle to the total intake volume is optimized by the engine calibration according to the specific use occasion; this ratio affects the engine efficiency, power, and emissions. In the occasion where it is easy to arrange and carry the gas tank, the proportion of compressed air sprayed by the jet nozzle to the total intake volume is larger.

[0018] Preferably, the engine body is also provided with a precombustion chamber, on which an air-assisted nozzle is arranged, the air-assisted nozzle is connected to a compressed air rail, the fuel injector and the air-assisted nozzle are both connected to a high-pressure fuel rail, and the jet direction of the spray hole of the air-assisted nozzle is designed to prevent the injected mixed gas from directly flowing out of the precombustion chamber; in the late compression stroke, the air-assisted nozzle sprays cooling compressed air into the engine precombustion chamber to reduce the gas temperature in the precombustion chamber; reduce the generation of NOx; and the amount of cooling compressed air injected is controlled to be about 3-5% of the engine intake volume.

[0019] The present invention also provides a method for operating a fuel engine integrating cooled compressed air, wherein the air supply system is replaced by a multi-stage compressor, and air is supplied to the engine through a compressed air rail or an intake manifold, and the driving wheel of the multi-stage compressor is driven by a motor or an engine; the closer the compression process of the multi-stage compressor is to isothermal compression, the less power is consumed; the cylinder of the compressor and the outlets of each stage of compression are cooled.

[0020] The present invention also provides a method for operating a fuel engine integrating cooling compressed air, comprising the following steps:

[0021] S1: The air supply mechanism for cooling compressed air adopts a compressed air tank;

[0022] S2: Cooling compressed air is introduced into the engine cylinder in the early stage of the intake stroke or the late stage of the compression stroke, which increases the engine intake volume, reduces the negative compression work done by the engine on this part of the gas during the compression stroke, reduces the temperature at the end of the engine compression, reduces the engine combustion temperature, reduces engine knock, and reduces the NOx generation rate; the energy stored in the compressed air is released to do work during the engine expansion stroke, thereby improving the engine thermal efficiency;

[0023] When the cooling compressed air is introduced into the engine cylinder in the early stage of the intake stroke, the compressed air enters the main combustion chamber of the engine through the intake valve, or the cooling compressed air is sprayed into the main combustion chamber of the engine through the jet nozzle, and the arrangement of the jet nozzle is such that the flow direction of the injected gas is consistent with the flow direction of the gas flowing into the intake valve, thereby increasing the tumble flow in the cylinder, improving the mixing process in the cylinder, and increasing the combustion speed;

[0024] When the cooling compressed air is introduced into the engine cylinder at the end of the compression stroke, the cooling compressed air is sprayed into the engine pre-combustion chamber by the air-assisted nozzle, which reduces the gas temperature in the pre-combustion chamber, reduces the NOx generation rate, increases the engine intake volume, saves the engine compression work, and improves the power and efficiency;

[0025] S3: Cooling compressed air is supplied by a multi-stage compressor.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention reduces the compression of the compressed air, reduces the negative work done by the engine compression stroke, reduces the temperature of the mixed gas at the end of the compression stroke, reduces the engine combustion temperature, reduces engine knock, allows a higher geometric compression ratio, reduces the original NOx emission, increases the engine intake volume, and the energy stored in the compressed air is released to do work in the engine expansion stroke, thereby improving the engine power and thermal efficiency. The present invention is applicable to spark ignition engines and can also be used for compression ignition engines, and has better effects on spark ignition engines.

[0027] The above summary is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments and features described above, further aspects, embodiments and features of the present invention will be readily apparent by reference to the accompanying drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the present invention;

[0029] Figure 2 This is a schematic diagram of the structure of Embodiment 2 of the present invention;

[0030] Figure 3 This is a schematic diagram of the structure of Embodiment 3 of the present invention;

[0031] Figure 4 This is a structural schematic diagram of Example 4 of the present invention.

[0032] In the figure: 1. Engine body; 2a. Main combustion chamber; 2b. Pre-combustion chamber; 3. Intake valve; 4. Exhaust valve; 5. Spark plug; 6. Injector; 7a. Jet nozzle; 7b. Air-assisted nozzle; 8. Piston; 9. High-pressure oil rail; 11. Air hole; 12. Compressed air rail; 13. Air flow meter; 14. Secondary pressure reducing valve; 15. Primary pressure reducing valve; 16. Air supply pipe; 17. Compressed air tank; 18. Intake manifold; 19. Intake duct; 20. Multi-stage compressor; 21. Drive wheel. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Example 1

[0035] See also Figure 1, the fuel engine running system structure integrating cooling compressed air includes:

[0036] The engine body 1 is provided with a main combustion chamber 2a, and the main combustion chamber 2a is provided with an injector 6 and a spark plug 5. The main combustion chamber 2a is provided with an intake valve 3 and an exhaust valve 4 correspondingly.

[0037] Air supply mechanism, the air supply mechanism adopts a compressed air tank 17. The pressure of the compressed air tank 17 is 350bar or 700bar. The greater the pressure, the smaller the volume of the tank is required, and the smaller the layout space is. The compressed air tank 17 is connected to the intake manifold 18 through the air supply pipe 16, and the intake manifold 18 is connected to the intake valve 3 through the intake duct 19. The air supply pipe 16 is provided with a primary pressure reducing valve 15, a secondary pressure reducing valve 14 and an air flow meter 13. The compressed air enters the engine cylinder through the primary pressure reducing valve 15, the secondary pressure reducing valve 14, the air flow meter 13, the intake manifold 18, and the intake valve 3. The secondary pressure reducing valve 14 is controlled by the engine control unit ECU.

[0038] In the early stage of the intake stroke, the cooled compressed air is introduced into the engine cylinder, and the compressed air enters the main combustion chamber 2a of the engine through the intake valve 3. The intake valve 3 is closed early to reduce the compression of the compressed air in the compression stroke and reduce the gas temperature at the end of compression.

[0039] The compressed air entering the engine cylinder undergoes the engine's intake, compression, combustion expansion, and exhaust strokes in the cylinder. During the intake stroke, the compressed gas expands and pushes the piston 8 to do positive work. During the compression stroke, the piston 8 compresses the gas and does negative work. The compressed air acts like a spring, and the positive and negative work cancel each other out. During the expansion stroke, the energy stored in the compressed air is released again to do positive work. Before the spark plug 5 ignites, the negative work done in the engine compression process accounts for about 10% of the effective work of the engine. Compressed air directly enters the cylinder in a high-pressure state in the early stage of the intake stroke, which can reduce the negative compression work done by the piston 8 in the compression stroke. Compressed air enters the cylinder in a high-pressure state, which can increase the intake volume and solve the problem of low power density of the Miller cycle and lean-burn engines.

[0040] Example 2

[0041] See also Figure 2 , the fuel engine running system structure integrating cooling compressed air includes:

[0042] The engine body 1 is provided with a main combustion chamber 2a, and the main combustion chamber 2a is provided with an injector 6, an air injection nozzle 7a and a spark plug 5. The main combustion chamber 2a is provided with an intake valve 3 and an exhaust valve 4 correspondingly.

[0043] Air supply mechanism, the air supply mechanism adopts a compressed air tank 17. The compressed air tank 17 is connected to the compressed air rail 12 through the air supply pipe 16, and the air supply pipe 16 is provided with a primary pressure reducing valve 15, a secondary pressure reducing valve 14 and an air flow meter 13. The compressed air enters the engine cylinder through the primary pressure reducing valve 15, the secondary pressure reducing valve 14, the air flow meter 13, the compressed air rail 12 and the air nozzle 7a. The secondary pressure reducing valve 14 and the air nozzle 7a are controlled by the engine control unit ECU.

[0044] In the early stage of the intake stroke, the cooling compressed air is introduced into the engine cylinder, and the cooling compressed air is sprayed into the main combustion chamber 2a of the engine by the air nozzle 7a. The arrangement of the air nozzle 7a should make the flow direction of the injected gas consistent with the flow direction of the gas flowing into the intake valve 3, so as to increase the tumble of the gas in the engine cylinder. High tumble promotes the mixing of gas and fuel, increases the turbulence in the cylinder, and improves the combustion speed of the mixed gas.

[0045] The jet nozzle 7a completes the jet before the intake valve 3 is closed, reducing the compression of the compressed air during the compression stroke and lowering the gas temperature at the end of compression. The greater the jet pressure, the shorter the required gas jet time, the less the compressed air is compressed during the compression stroke, the lower the gas temperature at the end of compression, the greater the Miller depth, that is, the greater the ratio of the engine expansion ratio to the compression ratio, the greater the improvement in engine efficiency. Generally, the jet time is controlled so that the effective compression ratio experienced by the compressed air is between 4 and 6.

[0046] The compressed air entering the engine cylinder from the jet nozzle 7a undergoes the engine's intake, compression, combustion, expansion, and exhaust strokes in the cylinder. During the intake stroke, the compressed gas expands and pushes the piston 8 to do positive work. During the compression stroke, the piston 8 compresses the gas and does negative work. The compressed air acts like a spring, and the positive and negative work cancel each other out. During the expansion stroke, the energy stored in the compressed air is released again to do positive work. Before the spark plug 5 ignites, the negative work done in the engine compression process accounts for about 10% of the effective work of the engine. The compressed air directly enters the cylinder in a high-pressure state in the early stage of the intake stroke, which can also reduce this part of the loss. The compressed air enters the cylinder in a high-pressure state, which can increase the intake volume and solve the problem of low power density of the Miller cycle and lean-burn engines.

[0047] In non-road use scenarios, the volume of the compressed air tank 17 is limited, and the proportion of gas entering the engine cylinder through the jet nozzle 7a can be larger. The specific proportion is related to the engine design and can be determined by calibration optimization. At this time, the engine geometric compression ratio can be very high, mainly limited by the manufacturing process. At this time, the engine effective efficiency can exceed 55%.

[0048] In the vehicle power scenario, the volume of the compressed air tank 17 is limited by the layout space. The weight of the compressed air also increases the energy consumption of the vehicle. At this time, the amount of air entering the cylinder from the jet nozzle 7a should be controlled at about 15%. At this time, the engine effective efficiency can exceed 50%.

[0049] Example 3

[0050] See also Figure 3 , the fuel engine running system structure integrating cooling compressed air includes:

[0051] The engine body 1 is provided with a main combustion chamber 2a and a pre-combustion chamber 2b, the main combustion chamber 2a is provided with a main combustion chamber nozzle 6, the pre-combustion chamber 2b is provided with an air-assisted nozzle 7b and a spark plug 5, an air hole 11 is provided at the bottom of the pre-combustion chamber 2b, the air-assisted nozzle 7b is connected to a compressed air rail 12, the main combustion chamber nozzle 6 and the air-assisted nozzle 7b are both connected to a high-pressure oil rail 9, and an intake valve 3 and an exhaust valve 4 are correspondingly provided on the main combustion chamber 2a.

[0052] The air supply mechanism adopts a compressed air tank 17, which is connected to the compressed air rail 12 through an air supply pipe 16. The air supply pipe 16 is provided with a primary pressure reducing valve 15, a secondary pressure reducing valve 14 and an air flow meter 13. The compressed air enters the engine pre-combustion chamber 2b through the primary pressure reducing valve 15, the secondary pressure reducing valve 14, the air flow meter 13, the compressed air rail 12 and the air assisting nozzle 7b. The secondary pressure reducing valve 14 and the air assisting nozzle 7b are controlled by the engine control unit ECU.

[0053] At the end of the compression stroke, the cooling compressed air is introduced into the engine cylinder, and the cooling compressed air is sprayed into the engine pre-combustion chamber 2b by the air-assisted nozzle 7b to reduce the gas temperature in the pre-combustion chamber 2b. The spray direction of the spray hole of the air-assisted nozzle 7b is designed to prevent the injected mixed gas from flowing out of the pre-combustion chamber 2b.

[0054] After the compressed air and fuel are mixed in the air-assisted nozzle 7b, they are sprayed into the pre-combustion chamber 2b. In the air-assisted nozzle 7b, the ratio of the air volume to the fuel volume is close to the equivalent ratio, that is, lambda is close to 1, and the ratio of air to gasoline is close to 14.7:1, which ensures the ignition energy of the pre-combustion chamber 2b.

[0055] The volume of the pre-combustion chamber 2b is generally 3%-5% of the cylinder volume when the piston 8 is at the top dead center. The pre-combustion chamber 2b is used in an engine with ultra-lean homogeneous combustion. In the main combustion chamber 2a, the ratio of air to fuel is close to lambda=2. The relative equivalent air-fuel ratio lambda in the pre-combustion chamber 2b is close to the equivalent ratio 1. The spark plug 5 ignites the mixture in the pre-combustion chamber 2b, and the temperature and pressure of the mixture in the pre-combustion chamber 2b rise sharply. Under the huge pressure difference between the inside and outside of the pre-combustion chamber 2b, the semi-burned mixture in the pre-combustion chamber 2b is ejected from the air hole 11, igniting the mixture in the main combustion chamber 2a. The temperature in the pre-combustion chamber 2b is much higher than the temperature in the main combustion chamber 2a.

[0056] The original emission of NOx is exponentially related to the temperature. For every 100-degree increase in temperature, the original emission of NOx increases by about 6 times. Therefore, the pre-combustion chamber 2b is the main source of NOx. Generally, if the compression ratio is reduced by 2 units, the temperature at the end of compression will be about 100 degrees lower. In the late stage of the compression stroke, a low-temperature mixed gas is sprayed into the pre-combustion chamber 2b, and the high-temperature gas inside is discharged, thereby reducing the temperature of the gas in the pre-combustion chamber 2b, which can effectively reduce the original emission of NOx, so that the post-treatment of the ultra-lean combustion engine does not require a complex SCR system to directly meet emission regulations. The purpose of injection in the late stage of the engine compression stroke is to reduce the temperature rise of the mixed gas injected into the pre-combustion chamber when it is compressed. In order to reduce the volume of the compressed air tank 17, the gas sprayed into the pre-combustion chamber 2b by the air-assisted nozzle 7b accounts for 3%-5% of the total intake volume.

[0057] The gas injected in the late stage of the compression stroke increases the engine intake volume and reduces the negative compression work. The energy stored in this part of the compressed gas is released in the expansion stroke to do positive work and improve the engine power and efficiency. Combined with the effect of ultra-lean combustion, the engine thermal efficiency is close to 50%.

[0058] Example 4

[0059] See also Figure 4 The difference between this embodiment and the third embodiment is that the air supply mechanism uses a multi-stage compressor 20. The driving wheel 21 of the multi-stage compressor 20 is driven by a motor or an engine. On a vehicle, the arrangement of the compressed air tank 17 is sometimes a challenge. In an ultra-lean combustion engine with a pre-combustion chamber 2b, the compressed air tank 17 is replaced by a vehicle-mounted multi-stage compressor.

[0060] Isothermal compression is the most efficient compression process. The more stages the multi-stage compressor 20 has, the closer the compression is to isothermal. Considering the cost of the compressor, two-stage compression is recommended. Taking air from the intake manifold of the turbocharger can save the power consumption required by the compressor, improve the thermal conductivity of the cylinder wall material of the compressor, improve the heat dissipation of the compression process, and make the compression process closer to isothermal compression. Aluminum nitride is wear-resistant, and its thermal conductivity is twice that of cast iron, making it a good cylinder wall material. For a compressor that supplies air specifically for the pre-combustion chamber 2b, the compressor displacement is about 3% of the engine displacement. In this way, the cost and layout space can be controlled. The compression stroke inside the engine is approximately adiabatic compression, and the compression efficiency is the lowest. The air is supplied by an external multi-stage compressor, and the temperature at the end of compression is low, and the power consumption is small. In the compression stroke, the later the air-assisted nozzle 7b is opened, the less compression the gas entering the cylinder from the air-assisted nozzle 7b is subjected to in the cylinder, and the lower the temperature. However, the higher the compression ratio required by the compressor, the greater the power consumed by the compressor. The gas entering the cylinder from the air-assisted nozzle 7b expands during the expansion stroke of the engine, increasing the effective work of the engine. Compressor design principle: Generally, the pressure in the compressed air rail 12 is about 3-5 bar greater than the pressure at the end of compression in the engine cylinder, ensuring that the intake volume in the pre-combustion chamber 2b meets the requirements. The gas entering the cylinder from the air-assisted nozzle 7b expands and does work during the expansion stroke of the engine, increasing the intake volume, reducing the negative work done by the compression stroke of the engine, increasing the effective work of the engine, and improving the effective thermal efficiency of the engine.

[0061] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0062] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0063] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0064] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A fuel engine operating system structure integrating cooling compressed air, characterized in that: include: An engine body (1), the engine body (1) being provided with a main combustion chamber (2a), the main combustion chamber (2a) being provided with a fuel injector (6) and a spark plug (5), and the main combustion chamber (2a) being provided with an intake valve (3) and an exhaust valve (4) correspondingly; An air supply mechanism adopts a compressed air tank (17) or a multi-stage compressor (20), the air supply mechanism is connected to a compressed air rail (12) or an intake manifold (18) through an air supply pipe (16), and supplies air to the engine through the compressed air rail (12) or the intake manifold (18), and a driving wheel (21) of the multi-stage compressor (20) is driven by a motor or an engine.

2. The fuel engine operating system structure integrating cooling compressed air according to claim 1 is characterized in that: The air supply mechanism adopts a compressed air tank (17) to supply air to the main combustion chamber (2a) of the engine, and the air supply pipe (16) is provided with a primary pressure reducing valve (15), a secondary pressure reducing valve (14) and an air flow meter (13).

3. The fuel engine operating system structure integrating cooling compressed air according to claim 2 is characterized in that: The compressed air enters the main combustion chamber (2a) of the engine through an intake manifold (18), an intake duct (19), and an intake valve (3); the intake valve is closed at an early stage of the intake stroke, the specific time of which is determined by the engine calibration, so as to reduce the compression of the compressed air during the compression stroke.

4. The fuel engine operating system structure integrating cooling compressed air according to claim 2 is characterized in that: The main combustion chamber (2a) is also provided with an air nozzle (7a), which is connected to a compressed air rail (12). The arrangement of the air nozzle (7a) is such that the flow direction of the injected gas is consistent with the flow direction of the gas flowing into the intake valve (3). The main combustion chamber (2a) inhales air from the outside through the intake valve (3), and the compressed air is injected into the main combustion chamber (2a) through the air nozzle (7a). This reduces the demand for compressed air. The air nozzle works in the early stage of the intake stroke, and the closing time of the intake valve is after the air nozzle stops working, and the specific time is determined by the engine calibration. The proportion of the compressed air injected by the air nozzle to the total intake volume is optimized by the engine calibration according to the specific use occasion. This proportion affects the engine efficiency, power and emission. In the occasion where the gas tank is easy to arrange and carry, the proportion of the compressed air injected by the air nozzle to the total intake volume is larger.

5. The fuel engine operating system structure integrating cooling compressed air according to claim 1 is characterized in that: The engine body (1) is also provided with a pre-combustion chamber (2b), and an air-assisted nozzle (7b) is arranged on the pre-combustion chamber (2b). The air-assisted nozzle (7b) is connected to a compressed air rail (12), and the fuel injector (6) and the air-assisted nozzle (7b) are both connected to a high-pressure fuel rail (9). The jet direction of the spray hole of the air-assisted nozzle (7b) is designed to prevent the injected mixed gas from directly flowing out of the pre-combustion chamber (2b); in the late stage of the compression stroke, the air-assisted nozzle (7b) sprays cooling compressed air into the engine pre-combustion chamber (2b), thereby reducing the gas temperature in the pre-combustion chamber (2b); reducing the amount of NOx generated; and the amount of cooling compressed air sprayed is controlled to be about 3-5% of the engine intake amount.

6. The operating method of the fuel engine operating system structure integrating cooling compressed air according to any one of claims 2 to 5, characterized in that: The air supply system is replaced by a multi-stage compressor, and air is supplied to the engine through a compressed air rail (12) or an intake manifold (18). The driving wheel (21) of the multi-stage compressor (20) is driven by a motor or an engine. The closer the compression process of the multi-stage compressor is to isothermal compression, the less power is consumed. The cylinder of the compressor and the outlets of each stage of compression are cooled.

7. The operating method of the fuel engine operating system structure integrating cooling compressed air according to any one of claims 1 to 6, characterized in that: The steps include: S1: The air supply mechanism for cooling compressed air adopts a compressed air tank (17); S2: Cooling compressed air is introduced into the engine cylinder in the early stage of the intake stroke or the late stage of the compression stroke, which increases the engine intake volume, reduces the compression of this part of the gas in the compression stroke, reduces the negative compression work done by the engine compression stroke, reduces the temperature at the end of the engine compression, reduces the engine combustion temperature, reduces engine knock, and reduces the NOx generation rate; The energy stored in the compressed air is released to do work during the engine expansion stroke, improving the engine's thermal efficiency; When the cooling compressed air is introduced into the engine cylinder at the early stage of the intake stroke, the compressed air enters the main combustion chamber (2a) of the engine through the intake valve (3), or the cooling compressed air is sprayed into the main combustion chamber (2a) of the engine through the jet nozzle (7a), and the arrangement of the jet nozzle (7a) is such that the flow direction of the injected gas is consistent with the flow direction of the gas flowing into the intake valve (3), thereby increasing the tumble flow in the cylinder, improving the mixing process in the cylinder, and increasing the combustion speed; When the cooling compressed air is introduced into the engine cylinder at the late stage of the compression stroke, the cooling compressed air is sprayed into the engine pre-combustion chamber (2b) by the air auxiliary nozzle (7b), thereby reducing the gas temperature in the pre-combustion chamber (2b), reducing the NOx generation rate, increasing the engine intake volume, saving the engine compression work, and improving the power and efficiency; S3: Cooling compressed air is supplied by a multi-stage compressor (20).

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