Escape gas separation apparatus, method, and escape gas recovery system

Abstract

The application discloses an escape gas separation device, an escape gas separation method and an escape gas recovery system, and belongs to the technical field of gas fuel engines, in particular to the escape gas recovery of a gas fuel engine. The device comprises a tee pipe, a return gas valve and a separation control subsystem. The return gas valve has two working states, namely an open state and a closed state. In the open state, the open cross-sectional area of the communication part between the exhaust passage inlet pipe and the exhaust passage outlet pipe 5.1 is 5% to 20% of the open cross-sectional area of the communication part between the exhaust passage inlet pipe and the return gas manifold. The escape gas separation device, the escape gas separation method and the escape gas recovery system are suitable for separating and recovering the escape gas in the gas fuel engine.

Description

Technical Field

[0001] This invention relates to the field of gas fuel engine technology, and more particularly to the recovery of escape gases from gas fuel engines. Background Technology

[0002] With increasing public awareness of energy conservation and environmental protection, engine emissions have become a growing concern. Replacing traditional fuels with alternative fuels has become a crucial solution to address engine emissions issues.

[0003] The alternative fuels mentioned are mostly gaseous fuels such as natural gas, hydrogen, or methanol. Engines that use these gaseous fuels are called gas-fueled engines. These gas-fueled engines have a similar structure to ordinary fuel engines, including a crankshaft, pistons, cylinders (engine cylinders), and a cylinder head. The cylinder head has intake valves (intake valves, intake valves) and exhaust valves (exhaust valves, exhaust valves).

[0004] The gas fuel supply methods for the gaseous fuel engine include, but are not limited to, port injection and direct injection. Port injection and direct injection are distinguished based on the injection location of the gaseous fuel. Port injection involves injecting gaseous fuel into the intake manifold or intake port port, where it mixes with incoming fresh air before entering the cylinder. Direct injection involves injecting gaseous fuel directly into the cylinder, where it mixes with fresh air. Due to the properties of the gaseous fuel itself, the exhaust valve on the cylinder must be closed before the gaseous fuel enters the cylinder.

[0005] In the operation of the gas-fueled engine, to ensure that the engine cylinders are filled with fresh gas, the intake valves and exhaust valves are open simultaneously. The time during which the intake and exhaust valves are open simultaneously is represented by crankshaft rotation angle and is called the valve overlap angle. Within the time range of the valve overlap angle, some gaseous fuel may enter the cylinder and then exit through the exhaust valve; this portion of gaseous fuel leaving the cylinder is called escape gas.

[0006] The presence of escape gases not only leads to the loss and waste of gaseous fuel, but also deteriorates the exhaust quality of gas-fueled engines, which is detrimental to environmental protection.

[0007] To address the aforementioned escape gas problem, existing gas fuel aftertreatment devices are generally located at the main exhaust outlet of gas fuel engines. These devices process gases that are mixtures of exhaust gas and escape gas within the exhaust pipe. The concentration of gaseous fuel in the mixture is low, making it difficult to separate the mixture. Summary of the Invention

[0008] This invention proposes an escape gas separation device, method, and escape gas recovery system, which solves the problem that escape gas in existing gas fuel engines is difficult to separate from exhaust gas and cannot be recovered and reused.

[0009] The escape gas separation device for a gas-fueled engine according to the present invention has the following technical solution:

[0010] The device includes a three-way valve, a return valve, and a separation control subsystem;

[0011] The three-way pipe includes an exhaust channel inlet pipe, an exhaust channel outlet pipe, and a return manifold.

[0012] The exhaust passage intake pipe is used to connect to the exhaust valve of one cylinder in the gas fuel engine;

[0013] The return air valve is embedded and fixed inside the three-way pipe; the return air valve has two working states: open state and closed state.

[0014] Open state: The cross-sectional area of ​​the connection between the exhaust channel inlet pipe and the exhaust channel outlet pipe is 5% to 20% of the cross-sectional area of ​​the connection between the exhaust channel inlet pipe and the return manifold.

[0015] Closed state: The connection between the exhaust channel inlet pipe and the exhaust channel outlet pipe is fully open, and the connection between the exhaust channel inlet pipe and the return manifold is fully closed.

[0016] Furthermore, in a preferred embodiment, the return valve 10 is a pushrod type valve.

[0017] This invention also proposes a method for separating escape gases in a gas-fueled engine, the technical solution of which is as follows:

[0018] The method employs the aforementioned escape gas separation device. The gas fuel engine comprises several cylinders, each cylinder including an intake valve, an exhaust valve, and a crankshaft. Each cylinder is connected to one of the escape gas separation devices, and the exhaust passage intake pipe of the escape gas separation device communicates with the exhaust valve of the cylinder. The method includes:

[0019] S1. Obtain the working status of the intake valve, exhaust valve, and crankshaft;

[0020] S2. Control the working state of the return valve according to the working state of the intake valve, exhaust valve and crankshaft;

[0021] S2.1 When either the intake valve or the exhaust valve is in the closed state:

[0022] The return air valve is kept in the closed state.

[0023] S2.2 When the exhaust valve is in the open state and the intake valve is in the closed state:

[0024] The working status of the intake valve is monitored in real time. When it switches from the closed state to the open state, the working status of the crankshaft is monitored in real time. After the crankshaft moves one crankshaft angle, the return valve is controlled to switch to the open state.

[0025] This invention also proposes an escape gas recovery system for a gas-fueled engine, the technical solution of which is as follows:

[0026] It includes a gas-fueled engine, which includes several cylinders, and the system also includes a fresh air intake pipe, a mixer, an intake manifold, an exhaust pipe, a one-way valve, a return pipe, and several of the aforementioned escape gas separation devices.

[0027] Each of the cylinders corresponds to a separate escape gas device; each cylinder is equipped with an intake valve and an exhaust valve; the exhaust valve of each cylinder is connected to the intake pipe of the exhaust channel in the corresponding escape gas separation device.

[0028] The fresh air intake pipe is connected to the air intake end of the mixer; the air outlet end of the mixer is connected to the air intake end of the main air intake pipe.

[0029] The intake valves of all cylinders are connected to the outlet end of the intake manifold;

[0030] The outlet end of the exhaust channel of each escape gas separator is connected to the inlet end of the exhaust pipe;

[0031] The outlet of the return manifold of each escape gas separator is connected to the inlet of the return pipe; the outlet of the return pipe is connected to the inlet of the mixer.

[0032] Furthermore, in a preferred embodiment, the system further includes a plurality of intake manifolds;

[0033] Each of the intake manifolds corresponds one-to-one with a number of cylinders;

[0034] Each of the intake manifolds is connected in series between the outlet end of the main intake pipe and the intake valve of the cylinder.

[0035] Furthermore, in a preferred embodiment, the recovery system further includes several control modules, each corresponding to an escape gas separation device;

[0036] The control module is used to collect the working status of the intake valve, exhaust valve and crankshaft of the cylinder; it is also used to control the working status of the return valve based on the working status of the intake valve, exhaust valve and crankshaft.

[0037] Furthermore, a preferred embodiment is provided, wherein the control module includes an information acquisition submodule and a return air regulation submodule;

[0038] The information acquisition submodule is used to acquire the working status of the intake valve, exhaust valve and crankshaft;

[0039] The return air control submodule is used to control the working state of the return air valve according to the working state of the intake valve, exhaust valve and crankshaft;

[0040] The return gas control submodule includes a return gas shut-off unit and a return gas open unit;

[0041] The return air shut-off unit is used to control the return air valve to be closed when one of the intake valve or the exhaust valve is in a closed state.

[0042] The return air opening unit is used to monitor the working status of the intake valve in real time when the exhaust valve is in the open state and the intake valve is in the closed state; to monitor the working status of the crankshaft in real time when the intake valve switches from the closed state to the open state; and to control the return air valve to switch to the open state after the crankshaft moves one crankshaft angle.

[0043] The present invention has the following beneficial effects:

[0044] 1. The escape gas separation device of the present invention, compared with the traditional escape gas treatment system that sets the treatment device at the engine exhaust outlet, can recover gaseous fuel with higher purity. This is because the traditional escape gas treatment system, which sets the treatment device at the engine exhaust outlet, results in a lower concentration of escape gas (i.e., recovered gaseous fuel) in the mixture of exhaust gas and escape gas obtained after treatment; while the present device, by delaying the opening of the intake valve for a certain period of time before opening the return valve, allows a large amount of exhaust gas to be discharged before separating and recovering the escape gas, thus resulting in a higher concentration of recovered gaseous fuel, which can be reused after recovery.

[0045] 2. The escape gas recovery system described in this invention can recover and reuse escape gas, reduce the loss and waste of gaseous fuel, improve the overall energy utilization efficiency of the engine, and improve the economy of the engine system.

[0046] 3. The escape gas recovery system described in this invention can recover and reuse escape gas, reduce air pollution from gaseous fuels, improve engine emission quality, and enhance the environmental friendliness of the engine system.

[0047] 4. The escape gas recovery system described in this invention can recover and reuse escape gas, reducing the amount of gaseous fuel in the exhaust gas emitted by the engine and improving the engine's emission performance.

[0048] 5. The escape gas recovery system of the present invention, through a one-way valve and a mixer, can directly utilize the recovered escape gas while ensuring stable air intake of the engine, without the need for separate storage containers. This improves the energy utilization rate of the generator and simplifies the gaseous fuel recovery process.

[0049] The escape gas separation device, method, and escape gas recovery system described in this invention are suitable for separating and recovering escape gases in gas-fueled engines. Attached Figure Description

[0050] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0051] Figure 1 This is a structural diagram of an escape gas recovery system according to one embodiment of the present invention;

[0052] Figure 2 This is a structural diagram of an escape gas separation device according to one embodiment of the present invention;

[0053] Figure 3 This is a schematic diagram of the pure exhaust stage, the intake and exhaust overlap stage, and the pure intake stage of a cylinder in one embodiment of the present invention. Attached image description:

[0055] 1. Fresh air intake pipe; 2. Mixer; 3. Intake main pipe; 3.1. Intake manifold; 4. Cylinder; 5. Exhaust pipe; 5.1. Exhaust passage outlet pipe; 6. T-pipe; 6.1. Exhaust passage intake pipe; 7. Return pipe; 7.1. Return manifold; 8. One-way valve; 9. Intake valve; 10. Return valve; 11. Exhaust valve; 12. Piston; 20. Cylinder head. Detailed Implementation

[0056] To make the technical solutions and advantages of the present invention clearer, the specific embodiments of the present invention will be described in further detail and completely below with reference to the accompanying drawings. The various embodiments described below are only some preferred embodiments of the present invention, and not all of them; the various embodiments described below are intended to explain the present invention and should not be construed as limiting the present invention; reasonable combinations of the technical features defined in the various embodiments of the present invention, as well as all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort, are all within the scope of protection of the present invention.

[0057] Implementation Method 1: Combination Figure 1 -3 This embodiment describes an escape gas separation device, and the specific implementation details are as follows:

[0058] The device includes a three-way pipe 6, a return valve 10, and a separation control subsystem;

[0059] The three-way pipe 6 includes an exhaust channel inlet pipe 6.1, an exhaust channel outlet pipe 5.1, and a return manifold 7.1;

[0060] The exhaust passage intake pipe 6.1 is used to connect to the exhaust valve 11 of one cylinder 4 in the gas fuel engine;

[0061] The return air valve 10 is embedded and fixed inside the three-way pipe 6; the return air valve 10 has two working states: open state and closed state.

[0062] Open state: The cross-sectional area of ​​the connection between the exhaust channel inlet pipe 6.1 and the exhaust channel outlet pipe 5.1 is 5% to 20% of the cross-sectional area of ​​the connection between the exhaust channel inlet pipe 6.1 and the return manifold 7.1;

[0063] Closed state: The connection between the exhaust channel inlet pipe 6.1 and the exhaust channel outlet pipe 5.1 is fully open, and the connection between the exhaust channel inlet pipe 6.1 and the return manifold 7.1 is fully closed.

[0064] In this embodiment, when the return air valve 10 is in the open state, the cross-sectional area of ​​the connection between the exhaust channel intake pipe 6.1 and the exhaust channel outlet pipe 5.1 is 5% to 20% of the cross-sectional area of ​​the connection between the exhaust channel intake pipe 6.1 and the return air manifold 7.1. That is, the connection between the exhaust channel intake pipe 6.1 and the exhaust channel outlet pipe 5.1 is not completely closed, but a certain gap is retained.

[0065] For example, when the return air valve 10 is in the open state, the cross-sectional area of ​​the connection between the exhaust channel intake pipe 6.1 and the exhaust channel outlet pipe 5.1 can be 10% or 5% of the cross-sectional area of ​​the connection between the exhaust channel intake pipe 6.1 and the return air manifold 7.1. At this time, most of the gas flowing out of the exhaust channel intake pipe 6.1 flows out of the return air manifold 7.1, and a small portion of the gas still flows out of the exhaust channel outlet pipe 5.1.

[0066] In this embodiment, the cylinder 4 includes a crankshaft, a piston 12, and a cylinder head 20;

[0067] The inner wall of the cylinder 4 and the cylinder head 20 together form a combustion chamber;

[0068] One end of the piston 12 is disposed in the combustion chamber; the other end of the piston 12 is connected to the crankshaft; the piston 12 is used to reciprocate in the combustion chamber and also to drive the crankshaft to move.

[0069] The cylinder head 20 is provided with an intake valve 9 and an exhaust valve 11;

[0070] The intake valve 9 is used to connect to the outlet end of the intake pipeline (such as the intake manifold 3.1) and control the connection and disconnection between the outlet end of the intake pipeline and the combustion chamber.

[0071] In this embodiment, when the escape gas separation device is in use, the intake end of the exhaust channel intake pipe 6.1 is connected to the exhaust valve 11 on the cylinder 4; the exhaust valve 11 is used to control the connection and disconnection between the intake end of the exhaust channel intake pipe 6.1 and the combustion chamber.

[0072] Implementation Method Two: Combination Figure 1 -3 This embodiment further defines the return gas valve 10 in the escape gas separation device described in Embodiment 1. The specific implementation details are as follows:

[0073] The return valve (10) is a push rod type valve.

[0074] In this embodiment, the structure of the return valve 10 is similar to that of the intake valve and the exhaust valve.

[0075] The return valve 10 includes a valve head and a valve stem.

[0076] The valve head is typically disc-shaped and 1 to 3 mm thick. It can be made of alloy steel (chromium steel, nickel-chromium steel) or heat-resistant alloy (silicon-chromium steel).

[0077] The valve stem, which is usually cylindrical, is fixedly connected to the valve head and is used to drive the valve head to move up and down in the three-way pipe, thereby adjusting the gas flow between the exhaust channel intake pipe 6.1 and the exhaust channel outlet pipe 5.1 or return manifold 7.1.

[0078] The return valve 10 may also include valve guides, valve springs, and other structures; these are common valve structures and will not be described in detail here.

[0079] Implementation Method 3: Combination Figure 1 -3 This embodiment describes a method for separating escape gases in a gas-fuel engine:

[0080] The method is implemented using the aforementioned escape gas separation device. The gas fuel engine includes several cylinders 4, each cylinder 4 including an intake valve 9, an exhaust valve 11, and a crankshaft. Each cylinder 4 is connected to one of the escape gas separation devices, and the exhaust passage intake pipe 6.1 of the escape gas separation device is connected to the exhaust valve 11 of the cylinder 4. The method includes:

[0081] S1. Obtain the working status of the intake valve 9, exhaust valve 11 and crankshaft;

[0082] S2. Control the working state of the return valve 10 according to the working state of the intake valve 9, the exhaust valve 11 and the crankshaft;

[0083] S2.1 When either the intake valve 9 or the exhaust valve 11 is in the closed state:

[0084] The return air valve 10 is kept in the closed state.

[0085] S2.2 When the exhaust valve 11 is in the open state and the intake valve 9 is in the closed state:

[0086] The working status of the intake valve 9 is monitored in real time. When it switches from the closed state to the open state, the working status of the crankshaft is monitored in real time. After the crankshaft moves one crankshaft angle, the return valve 10 is controlled to switch to the open state.

[0087] In this embodiment, the crankshaft rotates 360 degrees in one revolution. The piston's guide distribution can be controlled by setting the gas fuel injection time, the opening and closing time and angle of the intake or exhaust valves, and using the crankshaft rotation angle as a reference.

[0088] Crankshaft rotation angle is expressed in °CA, where 1°CA represents one degree of crankshaft rotation out of 360 degrees. Generally, 0°CA is defined as the piston reaching top dead center.

[0089] In this embodiment, the crankshaft moves by one crankshaft rotation angle, that is, the crankshaft rotates by one degree crankshaft rotation angle.

[0090] Implementation Method 4: Combination Figure 1 -3 This embodiment describes an escape gas recovery system, the specific implementation details of which are as follows:

[0091] It includes a gas fuel engine, which includes several cylinders 4. The system also includes a fresh air intake pipe 1, a mixer 2, an intake manifold 3, an exhaust pipe 5, a one-way valve 8, a return pipe 7, and several of the above-mentioned escape gas separation devices.

[0092] Each of the cylinders 4 corresponds to one of the escape gas separation devices; each cylinder 4 is equipped with an intake valve 9 and an exhaust valve 11; the exhaust valve 11 of each cylinder 4 is connected to the exhaust channel intake pipe 6.1 in the corresponding escape gas separation device.

[0093] The fresh air intake pipe 1 is connected to the air intake end of the mixer 2; the air outlet end of the mixer 2 is connected to the air intake end of the main air intake pipe 3.

[0094] The intake valves 9 of all cylinders 4 are connected to the outlet end of the intake manifold 3;

[0095] The outlet end of the exhaust channel outlet pipe 5.1 of each escape gas separation device is connected to the inlet end of the exhaust pipe 5;

[0096] The outlet end of the return manifold 7.1 of each escape gas separator is connected to the inlet end of the return pipe 7; the outlet end of the return pipe 7 is connected to the inlet end of the mixer 2.

[0097] Furthermore, the system also includes several intake manifolds 3.1;

[0098] The plurality of intake manifolds 3.1 correspond one-to-one with the plurality of cylinders 4;

[0099] Each of the intake manifolds 3.1 is connected in series between the outlet end of the main intake pipe 3 and the intake valve 9 of the cylinder 4.

[0100] Furthermore, the system also includes a gas fuel injection device for supplying gas fuel into the cylinder 4.

[0101] Furthermore, the gas fuel injection device is an intake manifold injection device, which is installed inside the intake manifold 3.

[0102] Furthermore, the gas fuel injection device is an in-cylinder injection device, which is installed inside the cylinder 4.

[0103] Furthermore, the gas fuel injection device is an intake manifold injection device, which is located inside the intake manifold 3.1.

[0104] In this embodiment, the cylinder 4, which uses the escape gas recovery system to separate and recover escape gas, has the following working stages:

[0105] Stage 1, Combustion and Work Stage:

[0106] The intake valve 9, exhaust valve 11 and return valve 10 are all in the closed state;

[0107] The mixed gas is compressed and performs work in the combustion chamber to generate exhaust gas;

[0108] in:

[0109] The mixed gas is a mixture of fresh air and gaseous fuel;

[0110] Phase 2, Pure Exhaust Phase:

[0111] The intake valve 9 and the return valve 10 are both in the closed state, and the exhaust valve 11 is in the open state;

[0112] The exhaust gas is discharged from the cylinder 4 through the exhaust outlet pipe 5.1 of the exhaust channel;

[0113] Phase 3, Intake and Exhaust Overlap Phase:

[0114] Both the exhaust valve 11 and the intake valve 9 are in the open state, and the return valve 10 is in the closed state.

[0115] The exhaust gas continues to be discharged from the cylinder 4 through the exhaust pipe 5.1 of the exhaust passage;

[0116] A new batch of fresh air and gaseous fuel mixture begins to enter the combustion chamber;

[0117] Phase 4, Gas Return Separation Phase:

[0118] After the intake valve 9 opens, the crankshaft rotates for a period of time, and the return valve 10 switches to the open state; at this time, the intake valve 9, exhaust valve 11, and return valve 10 are all in the open state.

[0119] A small portion of the exhaust gas continues to be discharged from cylinder 4 through the exhaust pipe 5.1 (at which point only a small gap remains);

[0120] The escaped gas is discharged from the cylinder 4 through the return manifold 7.1;

[0121] in:

[0122] The escaped gas is the portion of the gaseous fuel that did not participate in combustion in the newly entered batch of gaseous fuel;

[0123] Phase 5, Pure Intake Phase:

[0124] The intake valve 9 is in the open state, and the exhaust valve 11 and the return valve 10 are in the closed state;

[0125] The combustion chamber continues to receive the mixed gas;

[0126] After the crankshaft has rotated a certain angle, the intake valve 9 is closed, and the system re-enters stage 1, the combustion and power stage.

[0127] In this embodiment, the escape gas generated during the intake and exhaust overlap process of the gas fuel engine is controlled to enter the return gas pipe 7 by controlling the working state of the return gas valve 10.

[0128] In this embodiment, in the escape gas recovery system:

[0129] The plurality of cylinders sequentially separate and discharge exhaust gas and escape gas according to the firing order, wherein:

[0130] The exhaust gas is discharged into the air through exhaust pipe 5;

[0131] All escaped gases flow into the return pipe 7 sequentially according to the phase difference of each return valve 10 opening and closing, mix, and then enter the mixer 2 under the restriction of the one-way valve 8, and re-enter the cylinder 4 together with the engine intake air (fresh air).

[0132] In this embodiment, in the escape gas recovery system, since the intake manifold 1 (and intake manifold 3), mixer 2, cylinder 4, three-way pipe 6 and return pipe 7 form a passage, it is necessary to ensure that the gas pressure in the return pipe 7 is greater than the intake pressure of the intake manifold 1; otherwise, the fresh air in the intake system will flow back into the cylinder 4 through the return pipe 7.

[0133] In the escape gas recovery system, the following two methods are used to ensure that fresh air in the intake system does not flow back into cylinder 4 through return pipe 7:

[0134] 1. A one-way valve 8 is installed to prevent fresh air in the intake system from flowing back into the cylinder 4 through the return pipe 7.

[0135] 2. When the return valve is in the open state, the connection between the exhaust channel intake pipe (6.1) and the exhaust channel outlet pipe (5.1) remains open to a certain extent, that is, a gap of a set size is left. At the same time, under the inertia of the crankshaft, the direction of gas flow of cylinder 4 to exhaust outward will not change, thereby compressing the gas in the return pipe 7, making the gas pressure in the return pipe 7 greater than the gas pressure of the intake system, thereby ensuring that fresh air in the intake system flows back into cylinder 4 through the return pipe 7.

[0136] Implementation Method 5: Combination Figure 1 -3 This embodiment further defines the escape gas recovery system described in Embodiment 4:

[0137] The recovery system also includes several control modules, each corresponding to an escape gas separation device;

[0138] The control module is used to collect the working status of the intake valve 9, exhaust valve 11 and crankshaft of cylinder 4; and is also used to control the working status of the return valve 10 according to the working status of the intake valve 9, exhaust valve 11 and crankshaft.

[0139] Specifically, the control module includes an information acquisition submodule and a return gas regulation submodule;

[0140] The information acquisition submodule is used to acquire the working status of the intake valve 9, the exhaust valve 11, and the crankshaft;

[0141] The return air control submodule is used to control the working state of the return air valve 10 according to the working state of the intake valve 9, the exhaust valve 11 and the crankshaft.

[0142] The return gas control submodule includes a return gas shut-off unit and a return gas open unit;

[0143] The return air shut-off unit is used to control the return air valve 10 to be closed when one of the intake valve 9 or the exhaust valve 11 is in a closed state.

[0144] The return air opening unit is used to monitor the working status of the intake valve 9 in real time when the exhaust valve 11 is in the open state and the intake valve 9 is in the closed state; to monitor the working status of the crankshaft in real time when the intake valve 9 switches from the closed state to the open state; and to control the return air valve 10 to switch to the open state after the crankshaft moves one crankshaft angle.

[0145] The above description of several specific embodiments further details the technical solution provided by the present invention in order to highlight the advantages and benefits of the technical solution provided by the present invention. However, the above-described specific embodiments are not intended to limit the present invention. Any reasonable modifications and improvements to the present invention, reasonable combinations of embodiments, and equivalent substitutions based on the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for separating escape gases in a gas-fueled engine, characterized in that, The escape gas separation method is implemented based on an escape gas separation device; The escape gas separation device includes a three-way pipe (6), a return gas valve (10), and a separation control subsystem; The three-way pipe (6) includes an exhaust channel inlet pipe (6.1), an exhaust channel outlet pipe (5.1), and a return manifold (7.1). The exhaust passage intake pipe (6.1) is used to connect to the exhaust valve (11) of a cylinder (4) in the gas fuel engine. The return valve (10) is embedded and fixed inside the three-way pipe (6); the return valve (10) has two working states: open state and closed state; Open state: The cross-sectional area of ​​the connection between the exhaust channel inlet pipe (6.1) and the exhaust channel outlet pipe (5.1) is 5% to 20% of the cross-sectional area of ​​the connection between the exhaust channel inlet pipe (6.1) and the return manifold (7.1); Closed state: The connection between the exhaust channel inlet pipe (6.1) and the exhaust channel outlet pipe (5.1) is fully open, and the connection between the exhaust channel inlet pipe (6.1) and the return manifold (7.1) is fully closed; The gas fuel engine includes a number of cylinders (4), each cylinder (4) including an intake valve (9), an exhaust valve (11) and a crankshaft; each cylinder (4) is connected to an escape gas separation device, and the exhaust passage intake pipe (6.1) in the escape gas separation device is connected to the exhaust valve (11) of the cylinder (4); The escape gas separation method of the gas fuel engine includes: S1. Obtain the working status of the intake valve (9), exhaust valve (11) and crankshaft; S2. Control the working state of the return valve (10) according to the working state of the intake valve (9), exhaust valve (11) and crankshaft; S2.1 When either the intake valve (9) or the exhaust valve (11) is in the closed state: The return air valve (10) is controlled to be in the closed state; S2.2 When the exhaust valve (11) is in the open state and the intake valve (9) is in the closed state: The working status of the intake valve (9) is monitored in real time. When it switches from the closed state to the open state, the working status of the crankshaft is monitored in real time. When the crankshaft moves one crankshaft angle, the return valve (10) is controlled to switch to the open state.

2. The escape gas separation method according to claim 1, characterized in that, The return valve (10) is a push rod type valve.

3. A gas escape recovery system for a gas-fueled engine, comprising a gas-fueled engine, said gas-fueled engine including a plurality of cylinders (4), characterized in that, The escape gas recovery system is based on the escape gas separation method according to claim 1 or 2; The escape gas recovery system also includes a fresh air intake pipe (1), a mixer (2), an intake manifold (3), an exhaust pipe (5), a one-way valve (8), a return pipe (7), and several escape gas separation devices; The plurality of cylinders (4) correspond one-to-one with the plurality of escape gas separation devices; each cylinder (4) is provided with an intake valve (9) and an exhaust valve (11); the exhaust valve (11) of each cylinder (4) is connected to the exhaust channel intake pipe (6.1) in the corresponding escape gas separation device; The fresh air intake pipe (1) is connected to the air intake end of the mixer (2); the air outlet end of the mixer (2) is connected to the air intake end of the main air intake pipe (3); The intake valves (9) of all cylinders (4) are connected to the outlet end of the intake manifold (3); The outlet end of the exhaust channel outlet pipe (5.1) of each escape gas separation device is connected to the inlet end of the exhaust pipe (5); The outlet of the return manifold (7.1) of each escape gas separator is connected to the inlet of the return pipe (7); the outlet of the return pipe (7) is connected to the inlet of the mixer (2).

4. The escape gas recovery system according to claim 3, characterized in that, The system also includes several intake manifolds (3.1). Each of the intake manifolds (3.1) corresponds to one of the cylinders (4); Each of the intake manifolds (3.1) is connected in series between the outlet end of the main intake pipe (3) and the intake valve (9) of the cylinder (4).

5. The escape gas recovery system according to claim 4, characterized in that, The recovery system also includes several control modules, each corresponding to an escape gas separation device; The control module is used to collect the working status of the intake valve (9), exhaust valve (11) of the cylinder (4) and the crankshaft; it is also used to control the working status of the return valve (10) according to the working status of the intake valve (9), exhaust valve (11) and the crankshaft.

6. The escape gas recovery system according to claim 5, characterized in that, The control module includes an information acquisition submodule and a return air regulation submodule; The information acquisition submodule is used to acquire the working status of the intake valve (9), the exhaust valve (11) and the crankshaft; The return air control submodule is used to control the working state of the return air valve (10) according to the working state of the intake valve (9), the exhaust valve (11) and the crankshaft; The return gas control submodule includes a return gas shut-off unit and a return gas open unit; The return air shut-off unit is used to control the return air valve (10) to be closed when one of the intake valve (9) or the exhaust valve (11) is in a closed state; The return air opening unit is used to monitor the working status of the intake valve (9) in real time when the exhaust valve (11) is in the open state and the intake valve (9) is in the closed state; to monitor the working status of the crankshaft in real time when the intake valve (9) switches from the closed state to the open state; and to control the return air valve (10) to switch to the open state after the crankshaft moves one crankshaft angle.

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