Driving device for achieving exhaust gas recirculation of two-stage pressurization system and control method

Abstract

The invention belongs to the technical field of engine turbochargers, and particularly relates to a driving device for achieving exhaust gas recirculation of a two-stage supercharging system and a control method. The driving device for achieving exhaust gas recirculation of the two-stage supercharging system comprises an engine, a low-pressure-stage turbocharger, a high-pressure-stage turbocharger, a low-pressure supercharging intercooler and a high-pressure supercharging intercooler, and the engine is connected with a high-pressure turbine air inlet pipe of the high-pressure-stage turbocharger through an engine exhaust pipe. The high-pressure turbine gas inlet pipe is communicated with a high-pressure turbine gas inlet of the high-pressure-stage turbocharger, the high-pressure turbine gas inlet pipe is provided with a high-low-pressure-stage exhaust regulating valve and an EGR driving valve in parallel, and through the innovatively-designed driving device, driving of circulating waste gas introduced into the EGR valve, pressure re-increasing and flexible control over introduced flow are achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of engine turbochargers, and particularly relates to a driving device and a control method for realizing exhaust gas recirculation of a two-stage supercharging system. BACKGROUND

[0002] Modern engines represented by aviation piston engines, marine engines and high-power commercial engines increasingly use two-stage supercharging systems to break through the power limit. The two-stage turbocharging technology represented by series or sequential series is the main technical form. Through the cooperation of the low-pressure stage and the high-pressure stage of the two-stage turbocharger, the technical index limit of the required air flow and the maximum pressure ratio in the high-power engine application scenario is solved, and the high-power engine is provided with a continuous supply of high-compression-ratio air to allow the engine to inject more fuel.

[0003] From the application scenario, the engine using the two-stage supercharging system has high power and high thermal efficiency, but from the emission angle, the high thermal load of the engine caused by the high power, the high maximum combustion temperature and the exhaust temperature of the engine, and the superposition of the oxygen-rich environment easily cause the increase of nitrogen oxide emissions. How to effectively control the low nitrogen oxide emissions of this type of high-efficiency and high-power engine has become the focus of research on high-power engines, especially high-power two-stage supercharging engines.

[0004] Currently, for high-efficiency single-stage supercharged engines, two technical routes are basically adopted in the industry to meet the above requirements. One is to use a high-efficiency SCR (selective catalytic reduction) system, and the other technical route is to use an EGR (exhaust gas recirculation) technology. The former is to catalytically reduce nitrogen oxides into nitrogen and water through off-engine catalytic reduction, and the latter is to use the characteristics of the multi-atomic structure of the specific heat capacity of the engine exhaust gas to control the generation of high-temperature, oxygen-rich and other high-nitrogen oxide operating environments by reducing the maximum combustion temperature of the engine, and to improve and reduce the emission of nitrogen oxides through in-engine combustion. For two-stage supercharged high-power engines, with the implementation of the national 6B emission regulations and the non-road T4F emission regulations, the combination of the SCR (selective catalytic reduction) system and the EGR (exhaust gas recirculation) system has become a development trend to control the amount of nitrogen oxide emissions.

[0005] Currently, the EGR technology (exhaust gas recirculation technology) basically adopts high-pressure circulation EGR, such as Figure 1As shown, the structure directly takes a part of exhaust gas (about 5%-25% of the total amount of exhaust gas) from the engine exhaust pipe, passes through the high-pressure circulating EGR valve into the engine supercharging intake pipe, mixes with the compressed air of the supercharger, and enters the engine cylinder to burn and work, in order to realize this circulation, the pressure Pt in the EGR front pipeline connected with the high-pressure circulating EGR valve needs to be greater than the pressure Pc in the EGR rear pipeline, so that the normal and one-way flow of the exhaust gas taken by the EGR (exhaust gas recirculation) can be realized, and this application requirement requires a higher inlet pressure (Pt) at the front end of the turbocharger turbine, for the engine, especially for the engine using two-stage supercharging, the exhaust resistance increases rapidly, and at the same time, the supercharging pressure (Pc) at the compressor end is also greatly limited, which is not conducive to the efficient operation of the engine turbocharger, and is more not conducive to the efficient combustion and power output of the engine.

[0006] In order to meet the application boundary (Pt>Pc) of the high-pressure circulating EGR, in actual application, the turbine shell section of the turbocharger is continuously reduced to ensure a relatively high pre-turbine pressure Pt, and at the same time, the exhaust bypass structure of the turbocharger is used to limit the speed of the supercharger, and the design of the supercharging characteristics of the compressor impeller is combined to obtain a relatively low post-supercharging pressure Pc, so as to realize the EGR recirculation, and such a structure feature causes the pump suction loss of the engine to be too large after work, resulting in a decrease in engine efficiency, for the turbocharger alone, the high pre-turbine pressure is lower than the post-supercharging pressure (Pt>Pc), which will cause the efficiency of the supercharger to decrease, but at least the application requirement can be met, however, for the two-stage supercharging system, the low post-supercharging pressure requirement is not conducive to meeting the requirement of high power of the engine, and the decrease in engine efficiency caused by the high pre-turbine pressure will directly cause the engine to deteriorate, therefore, how to solve the problem caused by the high-pressure exhaust gas recirculation (EGR) requirement of the two-stage supercharging system engine is a technical challenge in a new application scenario. SUMMARY

[0007] The main technical problem to be solved by the present application is to provide a driving device for realizing exhaust gas recirculation of a two-stage supercharging system, which can fully utilize the pressure difference between the two-stage supercharging system, combine the control strategy of the two-stage supercharging system, realize the front and rear driving pressures required for the one-way flow of the circulating exhaust gas, solve the problem of the influence of the pressure difference of the engine single-stage supercharger on the engine and the efficiency of the supercharger, and realize the driving, pressure promotion and flexible control of the introduced circulating exhaust gas of the EGR valve through the innovative design of the driving device.

[0008] To solve the above technical problems, the present application provides the following technical scheme: A kind of drive device for realizing exhaust gas recirculation of two-stage supercharging system, including including engine, low-pressure stage turbocharger, high-pressure stage turbocharger, low-pressure supercharging intercooler and high-pressure supercharging intercooler, engine is connected with the high-pressure turbine intake pipe of high-pressure stage turbocharger by engine exhaust pipe, high-pressure turbine intake pipe is communicated with the high-pressure turbine intake port of high-pressure stage turbocharger, high-pressure turbine intake pipe is provided with high-low pressure stage exhaust gas regulating valve and EGR drive valve in parallel, high-low pressure stage exhaust gas regulating valve is connected with engine exhaust pipe by exhaust gas regulating valve intake pipe, EGR drive valve is connected with engine exhaust pipe by EGR drive valve intake pipe, the high-pressure turbine outlet pipe of high-pressure stage turbocharger and the exhaust gas regulating valve outlet pipe of high-low pressure stage exhaust gas regulating valve are all connected with the low-pressure turbine intake pipe of low-pressure stage turbocharger.

[0009] The following is the further optimization of the technical solutions of the application to the above-mentioned technical solutions: The EGR drive valve outlet pipe of EGR drive valve is connected with EGR valve intercooler, and the EGR valve intercooler is connected with EGR reversing valve through EGR reversing valve inlet pipe.

[0010] Further optimization: the EGR reversing valve low-pressure stage inlet connection pipe of EGR reversing valve is connected with the low-pressure compressor intake pipe of low-pressure stage turbocharger, and the EGR reversing valve high-pressure stage inlet connection pipe of EGR reversing valve is connected with the low-pressure supercharging intercooler pipe between low-pressure supercharging intercooler and high-pressure stage turbocharger.

[0011] Further optimization: EGR intercooler and EGR reversing valve are connected between EGR intercooler and EGR reversing valve, and EGR supercharger is driven by EGR supercharger drive device.

[0012] Further optimization: engine and EGR supercharger drive device are drivingly connected.

[0013] Further optimization: the compressor part of high-pressure stage turbocharger and low-pressure stage turbocharger is respectively provided with EGR high-pressure drive compressor and EGR low-pressure drive compressor.

[0014] Further optimization: the EGR high-pressure drive compressor is provided with an EGR high-pressure drive compressor air inlet and an EGR high-pressure drive compressor air outlet, the EGR reversing valve is communicated with the EGR high-pressure drive compressor air inlet through an EGR high-pressure drive compressor air inlet pipe, the EGR high-pressure drive compressor air outlet is communicated with the high-pressure compressor air outlet pipe of the high-pressure turbocharger through an EGR high-pressure drive compressor air outlet pipe, the EGR low-pressure drive compressor is provided with an EGR low-pressure drive compressor air inlet and an EGR low-pressure drive compressor air outlet, the EGR reversing valve is communicated with the EGR low-pressure drive compressor air inlet through an EGR low-pressure drive compressor air inlet pipe, and the EGR low-pressure drive compressor air outlet is communicated with the low-pressure turbocharger through an EGR low-pressure drive compressor air outlet pipe.

[0015] Further optimization: the EGR reversing valve low-pressure stage inlet connecting pipe of the EGR reversing valve is connected with the low-pressure compressor air inlet pipe of the low-pressure turbocharger, and the EGR reversing valve high-pressure stage inlet connecting pipe of the EGR reversing valve is connected with the low-pressure turbocharger.

[0016] The application further discloses a control method of a driving device for realizing exhaust gas recirculation of a two-stage turbocharging system. S1, in the process of starting and working of the engine, part of the exhaust gas in the engine exhaust pipe enters the EGR drive valve air inlet pipe, then unidirectionally flows into the EGR drive valve, after circulation gas flow control, is cooled and cooled by the EGR valve intercooler, enters the EGR reversing valve, and can be connected with the EGR reversing valve low-pressure stage inlet connecting pipe or the EGR reversing valve high-pressure stage inlet connecting pipe according to the control working condition, and the inlet pressure Peci of the EGR drive valve is the exhaust gas pressure Pt of the engine exhaust; S2, the high-low pressure stage exhaust regulating valve controls the cut-in time of the high-pressure turbocharger and the low-pressure turbocharger in the two-stage turbocharging system, and simultaneously serves as a control input of the EGR drive valve; S3, under low speed working condition of engine, high-low pressure stage exhaust adjusting valve is in closed state, main part of engine exhaust gas enters from high pressure turbine inlet, flows out from high pressure turbine outlet, pushes high pressure stage turbocharger to rotate and do work, meets engine work requirement, then low pressure exhaust gas after work is discharged through low pressure turbine outlet pipe of low pressure stage turbocharger, at this time, part of circulating exhaust gas enters EGR reversing valve after being regulated by EGR drive valve, connects EGR reversing valve high pressure stage inlet connecting pipe, after circulating exhaust gas and low pressure supercharged intercooler pipe are combined, enters high pressure compressor inlet, is compressed together with clean air, flows out from high pressure compressor outlet, realizes pressure lifting purpose, participates in engine combustion, at this time, pressure Peco2 of EGR reversing valve high pressure stage inlet connecting pipe is consistent with air pressure of low pressure compressor inlet pipe, at this time, Peci>Peco2 is met, circulating exhaust gas flows unidirectionally, realizes exhaust gas recirculation; S4, under high speed working condition of engine, high-low pressure stage exhaust adjusting valve is in fully open state, at this time, engine exhaust gas enters low pressure stage turbocharger through fully open high-low pressure stage exhaust adjusting valve, low pressure stage turbocharger works as main engine supercharging device, at this time, inlet pressure Peci of EGR drive valve is same as pressure in low pressure turbine inlet pipe, also same as engine exhaust pipe pressure, all are exhaust pressure P under this working condition of engine, in order to ensure smooth transmission of circulating gas, at this time, EGR reversing valve will connect EGR reversing valve low pressure stage inlet connecting pipe, circulating gas is connected with low pressure compressor inlet pipe, at this time, pressure Peco1 of EGR reversing valve low pressure stage inlet connecting pipe is same as pressure of low pressure compressor inlet pipe, at this time, Peci>Peco1 is met, circulating exhaust gas flows unidirectionally, realizes exhaust gas recirculation; S5, in the medium speed working condition of the engine, the high-low pressure stage exhaust regulating valve is in the flow regulating state, realizing the control of different opening degrees, at this time, the high temperature and high pressure exhaust gas of the engine enters the inlet pipe of the exhaust regulating valve through the exhaust pipe, and flows under the control of the high-low pressure stage exhaust regulating valve, at this time, the inlet pressure of the inlet pipe of the exhaust regulating valve is the same as the pressure of the high pressure turbine inlet pipe and the pressure of the EGR driving valve inlet pipe, and the inlet pressure Peci of the EGR driving valve is the pressure in the exhaust pipe of the engine, Pt, in the adjustment process, the pressure in the outlet pipe of the exhaust regulating valve is lower than the pressure in the inlet pipe of the exhaust regulating valve, the pressure difference of this part is the same as the pressure difference in the pipeline before and after the high pressure stage turbocharger, the high pressure stage turbocharger also participates in part of the supercharging work, part of the exhaust gas flowing out of the high pressure turbine outlet pipe and the exhaust gas flowing in the outlet pipe of the exhaust regulating valve are collected through the low pressure turbine inlet pipe, and then enter the low pressure stage turbocharger to drive the low pressure stage turbocharger to work, under the control of the high-low pressure stage exhaust regulating valve, the high pressure stage turbocharger and the low pressure stage turbocharger work together to realize the compression of air, the inlet pressure Peci of the EGR driving valve is the same as the pressure Pt in the exhaust pipe of the engine, the circulating gas unidirectionally flows in the EGR driving valve outlet pipe and the EGR valve cooler, and after cooling, enters the EGR reversing valve, the EGR reversing valve preferentially connects the high pressure stage inlet connecting pipe of the EGR reversing valve, at this time, the pressure of the high pressure stage inlet connecting pipe of the EGR reversing valve is Peco2, and Peci>Peco2 is met, the circulating exhaust gas unidirectionally flows to realize the exhaust gas recirculation.

[0017] Further optimization: the above control method further comprises the following steps: S6, the circulating gas is sucked from the EGR booster compressor inlet of the EGR driving supercharger, and flows out from the EGR booster compressor outlet after compression, at this time, the pressure is further increased, and after the control of the EGR reversing valve, the medium and small circulating flow enters the high pressure stage turbocharger through the high pressure stage inlet connecting pipe of the EGR reversing valve, and the large circulating flow enters the low pressure stage turbocharger through the low pressure stage inlet connecting pipe of the EGR reversing valve, the circulating gas pressures Peco2 and Peco1 entering the high pressure stage inlet connecting pipe of the EGR reversing valve and the low pressure stage inlet connecting pipe of the EGR reversing valve are further amplified under the action of the EGR driving supercharger, and are all greater than the pressure in the engine inlet pipe, so that a larger exhaust gas recirculation driving pressure is provided.

[0018] The technical scheme of the present application has at least the following beneficial effects: The application adopts the EGR drive valve structure, cooperates with the EGR reversing valve, can realize that the recirculated exhaust gas is controlled in flow by the EGR drive valve, selects different connecting pipes according to the driving pressure difference demand, and respectively enters the compressors of the high and low pressure stage turbochargers, realizes the recirculation drive of the circulating gas, and can meet the realization of the exhaust gas recirculation under the full working condition of the engine two-stage supercharging system. The EGR drive valve cooperates with the EGR drive supercharger structure in the application, improves the control ability of the EGR drive valve on the circulating exhaust gas when the low pressure stage supercharger works independently under the high speed working condition of the engine, can effectively consider the flow and pressure of the circulating exhaust gas, and meets the demand of the high power engine on the recirculated exhaust gas. The high and low pressure stage turbochargers in the application can adopt the one turbine double pressure structure, respectively integrate the EGR high pressure drive compressor and the EGR low pressure drive compressor, realize that the circulating exhaust gas is controlled in flow by the EGR drive valve, is controlled in flow direction by the EGR reversing valve according to the demand of different working conditions of the engine, respectively enters the EGR high pressure drive compressor or the EGR low pressure drive compressor, is actively pressurized, ensures that the circulating gas can enter the engine intake pipeline and participates in the engine combustion, and realizes the generation of the engine nitrogen oxide.

[0019] The application is further illustrated below in combination with the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is the installation structure schematic view of the high pressure circulating EGR valve of the engine of the background technology of the application; Figure 2 It is the connection structure schematic view of example 1 of the application; Figure 3 It is the connection structure schematic view of the deep cooling scheme of example 2 of the application; Figure 4 It is the connection structure schematic view of the independent supercharging scheme of example 3 of the application; Figure 5 It is the connection structure schematic view of the one turbine double pressure supercharging scheme of example 4 of the application.

[0021] In the diagram: 1-Engine; 2-Intake manifold; 3-Engine intake pipe; 4-High-pressure turbocharger intercooler; 5-EGR valve intercooler connection pipe; 6-EGR valve intercooler; 7-High-pressure compressor outlet pipe; 8-High-pressure compressor outlet; 9-High-pressure compressor inlet; 10-Low-pressure turbocharger intercooler pipe; 11-Low-pressure turbocharger intercooler; 12-Low-pressure turbocharger outlet pipe; 13-Low-pressure compressor outlet; 14-Low-pressure compressor inlet; 15-Air intake pipe; 16-Air filter; 17-Low-pressure compressor inlet pipe; 18-Exhaust pipe; 19-Muffler; 20-Aftertreatment device; 21-Low-pressure turbine outlet pipe; 22-Low-pressure turbine outlet; 23-Low-pressure turbine inlet; 24-Low-pressure stage turbocharger; 25-Low-pressure turbine intake pipe; 26-High-pressure turbine outlet; 27-High-pressure turbine inlet; 28-Exhaust regulating valve intake pipe; 29-High-pressure turbine intake pipe; 30-High-pressure stage turbocharger; 31-EGR valve intake pipe; 32-High-pressure cycle EGR valve; 33-EGR valve outlet pipe; 34-Engine exhaust pipe; 35-Exhaust manifold; 36-Engine cylinder; 37-High and low-pressure stage exhaust regulating valve; 38-Exhaust regulating valve outlet pipe; 39-EGR drive valve intake pipe; 40-EGR drive valve; 41-EGR drive valve outlet pipe; 42-EGR reversing valve inlet pipe; 43-EGR reversing valve; 44-EGR reversing valve low-pressure stage inlet connection pipe; 45-EGR reversing valve high-pressure stage inlet connection pipe; 46-EGR turbocharger; 47-EGR turbocharger drive unit; 48-EGR turbocharger compressor outlet; 49-EGR turbocharger compressor inlet; 50-EGR high-pressure drive compressor; 51-EGR high-pressure drive compressor outlet pipe; 52-EGR high-pressure drive compressor outlet; 53-EGR high-pressure drive compressor inlet; 54-EGR high-pressure drive compressor inlet pipe; 55-EGR low-pressure drive compressor inlet pipe; 56-EGR low-pressure drive compressor outlet pipe; 57-EGR low-pressure drive compressor outlet; 58-EGR low-pressure drive compressor inlet; 59-EGR low-pressure drive compressor; 60-High-pressure turbine outlet pipe. Detailed Implementation

[0022] Example 1: like Figure 2 As shown, a drive device for a two-stage turbocharging system to achieve exhaust gas recirculation includes an engine 1, a low-pressure stage turbocharger 24, a high-pressure stage turbocharger 30, a low-pressure turbocharger intercooler 11, and a high-pressure turbocharger intercooler 4. An engine cylinder 36 is provided inside the engine 1.

[0023] The engine 1 is provided with an intake manifold 2 and an exhaust manifold 35, the exhaust manifold 35 is connected with the high-pressure turbine intake pipe 29 of the high-pressure turbocharger 30 through the engine exhaust pipe 34, the high-pressure turbine intake pipe 29 is communicated with the high-pressure turbine intake port 27 of the high-pressure turbocharger 30, and the high-pressure turbine intake pipe 29 is provided with the high-low pressure exhaust regulating valve 37 and the EGR driving valve 40 in parallel.

[0024] The high-low pressure exhaust regulating valve 37 is connected with the engine exhaust pipe 34 through the exhaust regulating valve intake pipe 28, and the EGR driving valve 40 is connected with the engine exhaust pipe 34 through the EGR driving valve intake pipe 39.

[0025] In this way, the inlet of the high-low pressure exhaust regulating valve 37 and the EGR driving valve 40 are also connected with the engine exhaust pipe 34, that is, the inlet pressure is the same, which is the engine exhaust pressure Pt.

[0026] The high-pressure turbine exhaust pipe 60 of the high-pressure turbocharger 30 and the exhaust regulating valve exhaust pipe 38 of the high-low pressure exhaust regulating valve 37 are connected with the low-pressure turbine intake pipe 25 of the low-pressure turbocharger 24, the high-pressure turbine exhaust pipe 60 is communicated with the high-pressure turbine exhaust port 26 of the high-pressure turbocharger 30, and the low-pressure turbine intake pipe 25 is communicated with the low-pressure turbine intake port 23 of the low-pressure turbocharger 24.

[0027] The low-pressure turbine exhaust pipe 21 of the low-pressure turbocharger 24 is sequentially connected with the aftertreatment device 20, the muffler 19 and the exhaust pipe 18, and the low-pressure turbine exhaust pipe 21 is communicated with the low-pressure turbine exhaust port 22 of the low-pressure turbocharger 24.

[0028] The low-pressure compressor intake pipe 17 of the low-pressure turbocharger 24 is sequentially connected with the air filter 16 and the air filter 15, and the low-pressure compressor intake pipe 17 is communicated with the low-pressure compressor intake port 14 of the low-pressure turbocharger 24.

[0029] The low-pressure supercharging exhaust pipe 12 of the low-pressure turbocharger 24 is connected with the low-pressure supercharging intercooler 11, the low-pressure supercharging exhaust pipe 12 is communicated with the low-pressure compressor exhaust port 13 of the low-pressure turbocharger 24, the low-pressure supercharging intercooler 11 and the high-pressure turbocharger 30 are connected through the low-pressure supercharging intercooling pipe 10, and the low-pressure supercharging intercooling pipe 10 is communicated with the high-pressure compressor intake port 9 of the high-pressure turbocharger 30.

[0030] The high-pressure compressor exhaust pipe 7 of the high-pressure turbocharger 30 is connected with the high-pressure supercharging intercooler 4, the high-pressure compressor exhaust pipe 7 is communicated with the high-pressure compressor exhaust port 8 of the high-pressure turbocharger 30, and the high-pressure supercharging intercooler 4 is connected with the intake manifold 2 through the engine intake pipe 3.

[0031] The EGR valve intercooler 6 is connected to the EGR drive valve outlet pipe 41 of the EGR drive valve 40, the EGR valve 43 is connected to the EGR valve intercooler 6 through the EGR valve inlet pipe 42, the EGR valve low-pressure stage inlet connection pipe 44 of the EGR valve 43 is connected to the low-pressure compressor inlet pipe 17, and the EGR valve high-pressure stage inlet connection pipe 45 of the EGR valve 43 is connected to the low-pressure supercharging intercooler pipe 10.

[0032] In the embodiment, the high-low stage exhaust regulating valve 37 has three states of closing, fully opening and regulating. In the low-speed working condition of the engine 1, the high-low stage exhaust regulating valve 37 is in the closing state, the high-pressure exhaust gas discharged from the engine exhaust pipe 34 enters the turbine of the high-pressure stage turbocharger 30 through the high-pressure turbine inlet pipe 29, and at this time, the high-pressure stage turbocharger 30 provides the required supercharged air for the engine 1. In the high-speed working condition of the engine 1, the high-low stage exhaust regulating valve 37 is in the fully open state, at this time, the high-pressure exhaust gas discharged from the engine exhaust pipe 34 directly flows through the low-pressure turbine inlet pipe 25 through the fully open high-low stage exhaust regulating valve 37, and then enters the turbine of the low-pressure stage turbocharger 24, at this time, the low-pressure stage turbocharger 24 provides the required supercharged air for the engine 1. In the medium-speed working condition of the engine 1, the high-low stage exhaust regulating valve 37 is in the flow regulating state, which can control the distribution ratio of the exhaust gas flow entering the high-pressure turbine inlet pipe 29 and the low-pressure turbine inlet pipe 38, at this time, the high-pressure stage turbocharger 30 and the low-pressure stage turbocharger 24 work simultaneously to achieve the purpose of two-stage supercharging.

[0033] The working state of the EGR drive valve 40 is directly related to the opening and closing state of the high-low stage exhaust regulating valve 37. In the low-speed working condition of the engine 1, the high-low stage exhaust regulating valve 37 is in the closing state, at this time, the EGR drive valve inlet pipe 39 connected to the EGR drive valve 40 is connected in parallel to one side of the high-pressure turbine inlet pipe 29, and the exhaust gas is taken from the engine exhaust pipe 34, at this time, the exhaust gas discharged from the engine 1 mainly enters the high-pressure stage turbocharger 30 through the high-pressure turbine inlet pipe 29, drives the high-pressure stage turbocharger 30 to work, and the low-pressure exhaust gas after work is connected to the low-pressure turbine inlet pipe 25 through the high-pressure turbine outlet pipe 60, and after the pressure is reduced, it flows through the turbine of the low-pressure stage turbocharger 24, the low-pressure turbine outlet pipe 21, the aftertreatment device 20 and the muffler 19, and is discharged into the atmosphere through the exhaust pipe 18.

[0034] In order to achieve the exhaust gas recirculation, a small part of the exhaust gas discharged from the engine 1 is regulated by the EGR drive valve 40 (the flow range can be controlled between 0-30% according to the requirement), and then flows into the EGR valve intercooler 6 through the EGR drive valve outlet pipe 41 to be cooled, with the temperature controlled below 200°C. The cooled exhaust gas flows into the EGR reversing valve 43 through the EGR reversing valve inlet pipe 42 in one-way. The exhaust gas from the EGR reversing valve 43 flows into the low-pressure supercharging intercooler pipe 10 through the EGR reversing valve high-pressure inlet connecting pipe 45.

[0035] Because the low-pressure turbocharger 24 does not participate in the supercharging in this working condition, the pressure in the low-pressure supercharging intercooler pipe 10 is approximately equal to the pressure in the air inlet pipe 15, and thus the pressure Peco2 in the EGR reversing valve high-pressure inlet connecting pipe 45 is far lower than the inlet pressure Peci in the EGR drive valve inlet pipe 39 (the same as the engine exhaust pressure Pt), so that the exhaust gas recirculation required by the engine 1 can be easily achieved, and the exhaust gas recirculation amount can be controlled according to the requirement.

[0036] In the high-speed working condition of the engine 1, the high-low pressure exhaust regulating valve 37 is fully open, and the high-temperature and high-pressure exhaust gas from the engine 1 flows into the parallel high-pressure turbine inlet pipe 29, the exhaust regulating valve inlet pipe 28 and the EGR drive valve inlet pipe 39 through the exhaust pipe 34. The gas in the high-pressure turbine inlet pipe 29 flows into the exhaust regulating valve outlet pipe 38 through the high-pressure turbine outlet pipe 60. In the fully open state of the high-low pressure exhaust regulating valve 37, the pressures in the exhaust regulating valve inlet pipe 28 and the exhaust regulating valve outlet pipe 38 are the same, and thus the pressures in the high-pressure turbine inlet pipe 29 and the high-pressure turbine outlet pipe 60 are also the same, i.e. there is no pressure difference in the turbine flow pipe of the high-pressure turbocharger 30, and thus the high-pressure turbocharger 30 does not work, i.e. does not supercharge. At this time, the high-pressure turbine inlet pipe 29 and the high-pressure turbine outlet pipe 60, together with the fully open high-low pressure exhaust regulating valve 37, regulate the high-temperature and high-pressure exhaust gas into the low-pressure turbine inlet pipe 25, and then the low-pressure turbocharger 24 is supercharged. At this time, only the low-pressure turbocharger 24 rotates at high speed to achieve the supercharging function.

[0037] The pressure in the front end of the EGR drive valve 40, the EGR drive valve intake pipe 39, is the same as the pressure in the exhaust gas regulating valve intake pipe 28, the exhaust gas regulating valve exhaust pipe 38, and the low-pressure turbine intake pipe 25, which is the exhaust pressure Pt of the engine 1, and after the EGR drive valve 40 adjusts the circulating exhaust gas flow according to the needs of the engine 1, the circulating exhaust gas flows unidirectionally into the EGR valve through the EGR drive valve exhaust pipe 41, is cooled in the EGR valve intercooler 6, the temperature is controlled to below 200°C, enters the EGR reversing valve 43 through the EGR reversing valve inlet pipe 42, the circulating exhaust gas flowing out of the EGR reversing valve 43 is connected to the low-pressure stage inlet connection pipe 44, mixed with clean air in the low-pressure compressor intake pipe 17, synchronously pressurized by the low-pressure stage turbocharger 24, and then flows through the low-pressure intercooler 11, the engine intake pipe 3, and other pipelines to enter the engine 1 to participate in combustion.

[0038] Because the inlet pressure Peci of the EGR drive valve 40 is the same as the engine exhaust pressure Pt under this working condition, the pressure Peco1 in the EGR reversing valve low-pressure stage inlet connection pipe 44 is the same as the pressure in the air intake pipe 15 and the low-pressure compressor intake pipe 17, which is the same as the ambient pressure P0, and at this time Peci>Peco1, the EGR drive valve can smoothly drive the circulating exhaust gas, and can control the amount of exhaust gas recirculation as needed.

[0039] Under the medium-speed working condition of the engine 1, the high-low pressure stage exhaust gas regulating valve 37 is in a flow regulating state, and different opening degrees can be controlled, at this time, the high-temperature and high-pressure exhaust gas of the engine 1 enters the exhaust gas regulating valve intake pipe 28 through the exhaust pipe 34, and flows under the control of the high-low pressure stage exhaust gas regulating valve 37, and at this time, the inlet pressure of the exhaust gas regulating valve intake pipe 28 is the same as the pressure of the high-pressure turbine intake pipe 29 and the pressure of the EGR drive valve intake pipe 39, and the inlet pressure Peci of the EGR drive valve 40 changes with the working condition of the engine 1 and the opening degree adjustment of the high-low pressure stage exhaust gas regulating valve 37, which is the pressure in the engine exhaust pipe 34, i.e., Pt.

[0040] Unlike the full-opening working condition of the high-low pressure stage exhaust gas regulating valve 37, during the adjustment process, the pressure in the exhaust gas regulating valve exhaust pipe 38 is lower than the pressure in the exhaust gas regulating valve intake pipe 28, and the pressure difference is the same as the pressure difference between the front and rear pipes of the high-pressure stage turbocharger 30, so the high-pressure stage turbocharger also participates in part of the pressurization work, and part of the exhaust gas flowing out of the high-pressure turbine exhaust pipe 60 and the exhaust gas flowing in the exhaust gas regulating valve exhaust pipe 38 are collected through the low-pressure turbine intake pipe 25, and then enter the low-pressure stage turbocharger 24 to drive the low-pressure stage turbocharger 24 to work.

[0041] Under this working condition, the high-pressure stage turbocharger 30 and the low-pressure stage turbocharger 24 work together under the control of the high-low pressure stage exhaust gas regulating valve 37 to compress air.

[0042] The inlet pressure Peci of the EGR drive valve 40 is the same as the pressure Pt in the engine exhaust pipe 34, and the circulating gas unidirectionally flows in the EGR drive valve outlet pipe 41 and the EGR valve intercooler 6, and then enters the EGR reversing valve 43 after being cooled, and the EGR reversing valve low-pressure stage inlet connecting pipe 44 or the EGR reversing valve high-pressure stage inlet connecting pipe 45 can be selected at this time, and the pressure Peco1 and Peco2 in the two pipes are both lower than the Peci pressure value, and the exhaust gas recirculation can be driven. Considering the shortest principle of the circulating gas path, the EGR reversing valve 43 preferentially connects the EGR reversing valve high-pressure stage inlet connecting pipe 45 under this working condition, the circulating gas is collected through the low-pressure intercooler pipe 10, flows through the compressor of the high-pressure turbocharger 30, and then enters the engine 1 after being cooled by the high-pressure intercooler 4 to participate in combustion and work.

[0043] In the embodiment, the high-pressure turbocharger 30, the low-pressure turbocharger 24, the high-low pressure exhaust regulating valve 37 and the aftertreatment device 20 are all prior art, wherein the high-pressure turbocharger 30, the low-pressure turbocharger 24 and the high-low pressure exhaust regulating valve 37 are two-stage turbocharging and control technology adopted to realize high-power output of the engine 1.

[0044] In summary, the application mainly innovatively designs an EGR drive valve 40 downstream of the engine exhaust pipe 34 when the engine 1 adopts a two-stage turbocharging system, the device is connected in parallel with the high-low pressure exhaust regulating valve 37 and the high-pressure turbine inlet pipe 29, and is connected with the engine exhaust pipe 34 through the drive valve inlet pipe 39, the inlet pressure Peci of the EGR drive valve 40 is the same as the engine exhaust pressure Pt under all working conditions of the engine 1, and the circulating gas after being regulated by the EGR drive valve 40 enters the EGR reversing valve 43 after being cooled by the EGR intercooler 6, and the output channel of the circulating gas can be selected according to different working conditions of the engine 1, the EGR reversing valve high-pressure stage inlet connecting pipe 45 is connected under low-speed and medium-speed working conditions of the engine 1, and the circulating gas pressure is Peco2 at this time, which is lower than the inlet pressure Peci of the EGR drive valve 40, and the circulating exhaust gas can be smoothly driven to flow, and the EGR reversing valve low-pressure stage inlet connecting pipe 44 is connected under high-speed working conditions of the engine 1, and the circulating gas pressure is Peco1 at this time, which is also lower than the inlet pressure Peci of the EGR drive valve 40, and the above process can smoothly ensure that the exhaust gas recirculation function of the two-stage turbocharging system of the engine is realized, and the engine 1 and the high-pressure turbocharger 30 and the low-pressure turbocharger 24 all work in the high-efficiency range.

[0045] In this way, the problem of the poor adaptability and the difficulty in achieving the boundary requirement of the engine exhaust pressure Pt≥engine intake pressure Pc in the prior art, in which the circulating exhaust gas is directly introduced from the engine exhaust pipe 34 through the high-pressure circulating EGR valve 32, cooled by the EGR valve intercooler 6, and then introduced into the engine intake pipe 3, is solved.

[0046] Embodiment 2 As an improvement, in order to solve the problem of high temperature of the circulating exhaust gas flowing from the EGR drive valve 40, the low-pressure intercooler 11 of the engine two-stage supercharging system can be used in combination with the EGR intercooler 6 for deep cooling treatment, so as to further reduce the temperature of the circulating gas and more effectively control the generation of nitrogen oxides.

[0047] As shown in Figure 3 , the outlet of the EGR reversing valve high-pressure stage inlet connecting pipe 45 is moved forward and connected with the low-pressure supercharging outlet pipe 12.

[0048] In this way, under the low-speed and medium-speed working conditions of the engine 1, the circulating exhaust gas regulated by the EGR drive valve 40 flows into the EGR valve intercooler in one direction through the EGR drive valve outlet pipe 41, is connected with the EGR reversing valve 43 through the EGR reversing valve high-pressure stage inlet connecting pipe 45, and at this time, the outlet of the EGR reversing valve high-pressure stage inlet connecting pipe 45 is connected with the low-pressure supercharging outlet pipe 12. The circulating gas is combined with the air flowing out of the low-pressure turbocharger 24, and then enters the low-pressure intercooler 11 for further cooling, so as to achieve the purpose of deep cooling of the circulating gas and further reduce the temperature of the circulating gas.

[0049] Embodiment 3 As shown in Figure 4 , based on embodiment 1, an EGR supercharger 46 is connected between the EGR intercooler 6 and the EGR reversing valve 43.

[0050] The EGR supercharger 46 is provided with an EGR supercharger compressor inlet 49 and an EGR supercharger compressor outlet 48, and the EGR supercharger 46 is driven to work by an EGR supercharger drive device 47.

[0051] In this design, an EGR turbocharger 46 is installed downstream of the EGR drive valve 40. The recirculated exhaust gas flowing in from the EGR drive valve 40 is introduced into the compressor of the EGR turbocharger 46 through the compressor inlet 49. After being compressed and pressurized, the recirculated exhaust gas flows out from the compressor outlet 48 of the EGR turbocharger and enters the EGR reversing valve 43. Then, according to the required flow rate and control strategy, it enters the high-pressure stage turbocharger 30 or the low-pressure stage turbocharger 24 through the high-pressure stage inlet connection pipe 45 or the low-pressure stage inlet connection pipe 44 of the EGR reversing valve. After being mixed with air, it enters the cylinder 36 of the engine 1 to participate in combustion and play a role in controlling the generation of nitrogen oxides.

[0052] In this embodiment, the power of the EGR turbocharger drive device 47 comes from the engine 1, and the engine 1 transmits power to the engine 1 through a belt drive transmission method.

[0053] The EGR turbocharger drive unit 47 uses a drive motor, and the power output end of the drive motor is connected to the impeller drive of the compressor of the EGR turbocharger 46.

[0054] With this design, the EGR turbocharger drive unit 47 is directly used to drive the compressor. At this time, it is only necessary to control and adjust the opening of the EGR drive valve 40 to regulate the flow rate of the circulating gas entering the compressor inlet 49 of the EGR turbocharger. The control operation is simple and precise. After the compressor pressurizes the circulating gas, it flows through the compressor outlet 48 of the EGR turbocharger to the EGR reversing valve 43, and finally enters the engine 1 to participate in combustion.

[0055] Example 4: like Figure 5 As shown, based on the above embodiment 1, the function of the EGR turbocharger 46 in embodiment 3 can also be implemented using the structure of this embodiment, with an EGR high-pressure drive compressor 50 and an EGR low-pressure drive compressor 59 respectively provided in the compressor sections of the high-pressure stage turbocharger 30 and the low-pressure stage turbocharger 24.

[0056] The EGR high-pressure driven compressor 50 is provided with an EGR high-pressure driven compressor inlet 53 and an EGR high-pressure driven compressor outlet 52. The EGR reversing valve 43 is connected to the EGR high-pressure driven compressor inlet 53 through the EGR high-pressure driven compressor inlet pipe 54, and the EGR high-pressure driven compressor outlet 52 is connected to the high-pressure compressor outlet pipe 7 through the EGR high-pressure driven compressor outlet pipe 51.

[0057] The EGR high-pressure drive compressor 50 is coaxially arranged with the compressor of the high-pressure stage turbocharger 30 and is driven to rotate by the turbine of the high-pressure stage turbocharger 30, realizing the "one vortex dual-pressure structure" of the high-pressure stage turbocharger 30.

[0058] The EGR low-pressure driven compressor 59 is provided with an EGR low-pressure driven compressor air inlet 58 and an EGR low-pressure driven compressor air outlet 57, the EGR reversing valve 43 is communicated with the EGR low-pressure driven compressor air inlet 58 through an EGR low-pressure driven compressor air inlet pipe 55, and the EGR low-pressure driven compressor air outlet 57 is communicated with the low-pressure supercharging air outlet pipe 12 through an EGR low-pressure driven compressor air outlet pipe 56.

[0059] The EGR low-pressure driven compressor 59 is coaxially arranged with the compressor of the low-pressure turbocharger 24, is driven to rotate by the turbine of the low-pressure turbocharger 24, and realizes the "one-turbine dual-pressure structure" of the low-pressure turbocharger.

[0060] The engine exhaust gas from the engine exhaust pipe 34 is regulated in flow by the EGR driving valve 40, and after the circulating gas passes through the EGR reversing valve 43, according to different operating conditions of the engine 1, the circulating gas can be connected to the EGR high-pressure driven compressor air inlet pipe 54 or the EGR low-pressure driven compressor air inlet pipe 55 for pressure boosting, so as to ensure the realization of the exhaust gas recirculation.

[0061] In this way, when the EGR reversing valve 43 is connected to the EGR high-pressure driven compressor air inlet pipe 54, the circulating gas enters the EGR high-pressure driven compressor 50 through the EGR high-pressure driven compressor air inlet 53, is compressed and boosted in pressure, and then flows out from the EGR high-pressure driven compressor air outlet 52. At this time, the pressure of the circulating exhaust gas is higher than the pressure Pt of the circulating gas entering from the engine exhaust pipe 34, so that the pressure in the EGR high-pressure driven compressor air outlet pipe 51 is greater than the pressure in the engine air inlet pipe 3, and the exhaust gas recirculation function is realized.

[0062] When the EGR reversing valve 43 is connected to the EGR low-pressure driven compressor air inlet pipe 55, the circulating gas enters the EGR low-pressure driven compressor 59 through the EGR low-pressure driven compressor air inlet 58, is compressed and boosted in pressure, and then flows out from the EGR low-pressure driven compressor air outlet 57. At this time, the pressure of the circulating exhaust gas is also higher than the pressure Pt of the circulating gas entering from the engine exhaust pipe 34, so that the pressure in the EGR low-pressure driven compressor air outlet pipe 56 is greater than the pressure in the low-pressure supercharging air outlet pipe 12, and the exhaust gas recirculation function is also realized.

[0063] In this embodiment, the compressors and turbines on the high-pressure turbocharger 30 and the low-pressure turbocharger 24 share a driving shaft with the EGR high-pressure driven compressor 50 and the EGR low-pressure driven compressor 59, respectively, and an additional EGR driven supercharger is not needed to realize the pressure boosting of the circulating gas, so as to realize the exhaust gas recirculation function, and the overall structure is more simple.

[0064] The application further discloses a control method of a driving device for realizing exhaust gas recirculation of a two-stage supercharging system. S1, in the process that the engine 1 starts to work, part of the exhaust gas in the engine exhaust pipe 34 enters the EGR driving valve air inlet pipe 39, then unidirectionally flows into the EGR driving valve 40, after the circulation gas flow control, is cooled by the EGR valve intercooler 6, enters the EGR reversing valve 43, and can be connected to the EGR reversing valve low-pressure stage inlet connecting pipe 44 or the EGR reversing valve high-pressure stage inlet connecting pipe 45 according to the control working condition; the inlet pressure Peci of the EGR driving valve 40 is the exhaust gas pressure Pt of the engine 1 exhaust; S2, the high-low pressure stage exhaust regulating valve 37 controls the cut-in time of the high-pressure stage turbocharger 30 and the low-pressure stage turbocharger 24 in the two-stage supercharging system, and simultaneously serves as the control input of the EGR driving valve 40; S3, in the low-speed working condition of the engine 1, the high-low pressure stage exhaust regulating valve 37 is in the closed state, the main part of the engine 1 exhaust gas enters from the high-pressure turbine air inlet 27 and flows out from the high-pressure turbine air outlet 26, drives the high-pressure stage turbocharger 30 to rotate and work, meets the working needs of the engine 1, then the low-pressure exhaust gas after work is discharged through the low-pressure turbine air outlet pipe 21 of the low-pressure stage turbocharger 24, at this time, part of the circulating exhaust gas enters the EGR reversing valve 43 after being regulated and controlled by the EGR driving valve 40, the EGR reversing valve high-pressure stage inlet connecting pipe 45 is connected, the circulating exhaust gas is combined with the low-pressure supercharged intercooler pipe 10, then enters the high-pressure compressor air inlet 9, is compressed together with clean air, flows out from the high-pressure compressor air outlet 8, realizes the pressure boosting purpose, participates in the combustion of the engine 1, at this time, the pressure Peco2 of the EGR reversing valve high-pressure stage inlet connecting pipe 45 is consistent with the air pressure of the low-pressure compressor air inlet pipe 17, at this time, Peci>Peco2 is met, the circulating exhaust gas unidirectionally flows, and the exhaust gas recirculation is realized; S4, under the high-speed working condition of the engine 1, the high-low pressure stage exhaust adjusting valve 37 is in the fully open state, at this time, the exhaust gas discharged from the engine 1 enters the low pressure stage turbocharger 24 through the fully open high-low pressure stage exhaust adjusting valve 37, the low pressure stage turbocharger 24 will work as the main supercharging device of the engine 1, at this time, the inlet pressure Peci of the EGR driving valve 40 is the same as the pressure in the low pressure turbine inlet pipe 25, and also the same as the pressure in the engine exhaust pipe 34, all of which are the exhaust pressure P of the engine 1 under this working condition, in order to ensure the smooth transmission of the circulating gas, at this time, the EGR reversing valve 43 will connect the EGR reversing valve low pressure stage inlet connecting pipe 44, the circulating gas is connected with the low pressure compressor inlet pipe 17, at this time, the pressure Peco1 of the EGR reversing valve low pressure stage inlet connecting pipe 44 is the same as the pressure of the low pressure compressor inlet pipe 17, and also consistent with the pressure of the air inlet pipe 15, at this time, Peci>Peco1 is met, the circulating exhaust gas flows unidirectionally, and the exhaust gas recirculation is realized; S5, under the medium-speed working condition of the engine 1, the high-low pressure stage exhaust adjusting valve 37 is in the flow adjusting state, realizing the control of different opening degrees, at this time, the high-temperature and high-pressure exhaust gas of the engine 1 enters the exhaust adjusting valve inlet pipe 28 through the exhaust pipe 34, and then flows under the control of the high-low pressure stage exhaust adjusting valve 37, at this time, the inlet pressure of the exhaust adjusting valve inlet pipe 28 is the same as the pressure of the high pressure turbine inlet pipe 29 and the pressure of the EGR driving valve inlet pipe 39, and changes with the working condition of the engine 1 and the opening degree adjustment of the high-low pressure stage exhaust adjusting valve 37, the inlet pressure Peci of the EGR driving valve 40 is the pressure Pt in the engine exhaust pipe 34, which is different from the fully open working condition of the high-low pressure stage exhaust adjusting valve 37, during the adjustment process, the pressure in the exhaust adjusting valve outlet pipe 38 is lower than the pressure in the exhaust adjusting valve inlet pipe 28, the pressure difference of this part is the same as the pressure difference in the front and rear pipes of the high pressure stage turbocharger 30, therefore, the high pressure stage turbocharger 30 also participates in part of the supercharging work, part of the exhaust gas flowing out of the high pressure turbine outlet pipe 60 and the exhaust gas flowing in the exhaust adjusting valve outlet pipe 38 are collected through the low pressure turbine inlet pipe 25, and then enter the low pressure stage turbocharger 24 to drive the low pressure stage turbocharger 24 to work, under this working condition, the high pressure stage turbocharger 30 and the low pressure stage turbocharger 24 work jointly under the control of the high-low pressure stage exhaust adjusting valve 37, realizing the compression of air, the inlet pressure Peci of the EGR driving valve 40 is the same as the pressure Pt in the engine exhaust pipe 34, the circulating gas unidirectionally flows in the EGR driving valve outlet pipe 41 and the EGR valve, is cooled after that, enters the EGR reversing valve 43, the EGR reversing valve 43 preferentially connects the EGR reversing valve high pressure stage inlet connecting pipe 45, at this time, the pressure of the EGR reversing valve high pressure stage inlet connecting pipe 45 is Peco2, and Peci>Peco2 is met, the circulating exhaust gas unidirectionally flows, realizing the exhaust gas recirculation; S6, in order to improve the engine 1 high speed condition, low pressure stage turbocharger 24 independent work, because of EGR drive valve 40 inlet pressure is low (the same as the engine exhaust pressure, for Pt), the circulating gas can not fully enter the high pressure stage turbocharger 30 problem, in the EGR drive valve 40 is located on the line set up an EGR drive turbocharger 46, circulating gas from the EGR turbocharger compressor inlet 49 of EGR drive turbocharger 46 suction, compression from the EGR turbocharger compressor outlet 48, at this time, the pressure will be further improved, after the EGR reversing valve 43 control, small circulating flow through the EGR reversing valve high pressure machine inlet connection 45 pipe into the high pressure stage turbocharger 30, large circulating flow through the EGR reversing valve low pressure stage inlet connection pipe 44 into the low pressure stage turbocharger 24, in the process, into the EGR reversing valve high pressure machine inlet connection 45 into the EGR reversing valve low pressure stage inlet connection pipe 44 of the circulating gas pressure Peco2 and Peco1 under the action of EGR drive turbocharger 46 further amplification, are greater than the pressure in the engine intake pipe 3, provide greater exhaust gas recirculation drive pressure.

[0065] For those skilled in the art, according to the teachings of the present application, without departing from the principles and spirit of the present application, the change, modification, replacement and variation of the embodiments still fall within the scope of the present application.

Claims

1. A drive device for implementing exhaust gas recirculation in a two-stage turbocharging system, comprising an engine (1), a low-pressure stage turbocharger (24), a high-pressure stage turbocharger (30), a low-pressure supercharging intercooler (11), and a high-pressure supercharging intercooler (4), characterized in that: The engine (1) is connected with the high-pressure turbine intake pipe (29) of the high-pressure turbocharger (30) through the engine exhaust pipe (34), the high-pressure turbine intake pipe (29) is communicated with the high-pressure turbine intake port (27) of the high-pressure turbocharger (30), the high-pressure turbine intake pipe (29) is provided with the high-low pressure exhaust regulating valve (37) and the EGR drive valve (40) in parallel, the high-low pressure exhaust regulating valve (37) is connected with the engine exhaust pipe (34) through the exhaust regulating valve intake pipe (28), the EGR drive valve (40) is connected with the engine exhaust pipe (34) through the EGR drive valve intake pipe (39), the high-pressure turbine exhaust pipe (60) of the high-pressure turbocharger (30) and the exhaust regulating valve exhaust pipe (38) of the high-low pressure exhaust regulating valve (37) are connected with the low-pressure turbine intake pipe (25) of the low-pressure turbocharger (24).

2. A drive device for implementing exhaust gas recirculation of a two-stage supercharging system according to claim 1, characterized in that: The EGR drive valve (40) is connected with the EGR valve intercooler (6), the EGR valve intercooler (6) is connected with the EGR reversing valve (43) through the EGR reversing valve inlet pipe (42).

3. A drive device for implementing exhaust gas recirculation for a two-stage supercharging system according to claim 2, characterized in that: The EGR reversing valve low-pressure stage inlet connection pipe (44) of the EGR reversing valve (43) is connected with the low-pressure compressor intake pipe (17) of the low-pressure turbocharger (24), the EGR reversing valve high-pressure stage inlet connection pipe (45) of the EGR reversing valve (43) is connected with the low-pressure supercharging intercooler pipe (10) between the low-pressure supercharging intercooler (11) and the high-pressure turbocharger (30).

4. A drive device for implementing exhaust gas recirculation of a two-stage supercharging system according to claim 3, characterized in that: The EGR intercooler (6) and the EGR reversing valve (43) are connected with the EGR supercharger (46), the EGR supercharger (46) is driven to work by the EGR supercharger drive device (47).

5. A drive device for implementing exhaust gas recirculation of a two-stage supercharging system according to claim 4, characterized in that: The engine (1) is drivingly connected with the EGR supercharger drive device (47).

6. A drive device for implementing exhaust gas recirculation of a two-stage supercharging system according to claim 2, characterized in that: The compressor parts of the high-pressure turbocharger (30) and the low-pressure turbocharger (24) are respectively provided with the EGR high-pressure drive compressor (50) and the EGR low-pressure drive compressor (59).

7. A drive device for implementing exhaust gas recirculation of a two-stage supercharging system according to claim 6, characterized in that: The EGR high-pressure drive compressor (50) is provided with an EGR high-pressure drive compressor air inlet (53) and an EGR high-pressure drive compressor air outlet (52), the EGR reversing valve (43) is communicated with the EGR high-pressure drive compressor air inlet (53) through an EGR high-pressure drive compressor air inlet pipe (54), the EGR high-pressure drive compressor air outlet (52) is communicated with the high-pressure compressor air outlet pipe (7) of the high-pressure turbocharger (30) through an EGR high-pressure drive compressor air outlet pipe (51), the EGR low-pressure drive compressor (59) is provided with an EGR low-pressure drive compressor air inlet (58) and an EGR low-pressure drive compressor air outlet (57), the EGR reversing valve (43) is communicated with the EGR low-pressure drive compressor air inlet (58) through an EGR low-pressure drive compressor air inlet pipe (55), and the EGR low-pressure drive compressor air outlet (57) is communicated with the low-pressure compressor air outlet pipe (12) of the low-pressure turbocharger (24) through an EGR low-pressure drive compressor air outlet pipe (56).

8. A drive device for implementing exhaust gas recirculation of a two-stage supercharging system according to claim 2, characterized in that: The EGR reversing valve low-pressure stage inlet connecting pipe (44) of the EGR reversing valve (43) is connected with the low-pressure compressor air inlet pipe (17) of the low-pressure turbocharger (24), and the EGR reversing valve high-pressure stage inlet connecting pipe (45) of the EGR reversing valve (43) is connected with the low-pressure compressor air outlet pipe (12) of the low-pressure turbocharger (24).

9. A control method of a drive device for an exhaust gas recirculation system of a two-stage supercharging system according to claim 5, characterized by: The method comprises the following steps: S1, in the process of starting and working of the engine (1), part of exhaust gas in the engine exhaust pipe (34) enters the EGR drive valve air inlet pipe (39), then unidirectionally flows into the EGR drive valve (40), after circulation gas flow control, is cooled by the EGR valve intercooler (6), enters the EGR reversing valve (43), can be connected with the EGR reversing valve low-pressure stage inlet connecting pipe (44) or the EGR reversing valve high-pressure stage inlet connecting pipe (45) according to the control working condition, and the inlet pressure Peci of the EGR drive valve (40) is the exhaust gas pressure Pt of the engine (1); S2, the high-low pressure stage exhaust regulating valve (37) controls the cut-in time of the high-pressure turbocharger (30) and the low-pressure turbocharger (24) in the two-stage supercharging system, and simultaneously serves as a control input of the EGR drive valve (40); S3, low speed working condition of engine (1), high-low pressure stage exhaust regulating valve (37) is closed state, engine (1) exhaust gas main part from high pressure turbine inlet (27) into, from high pressure turbine outlet (26) flow out, drive high pressure stage turbocharger (30) rotation work, meet the engine (1) work need, then after work, low pressure exhaust gas, through the low pressure stage turbocharger (24) low pressure turbine outlet pipe (21) discharge, at this time, a part of circulating exhaust gas after EGR drive valve (40) regulation and control into EGR reversing valve (43), connect EGR reversing valve high pressure stage inlet connecting pipe (45), circulating exhaust gas and low pressure after supercharging intercooler pipe (10) confluence, enter high pressure compressor inlet (9), same clean air compression, again from high pressure compressor outlet (8) flow out, realize the purpose of pressure increase, participate in engine (1) combustion, at this time, EGR reversing valve high pressure stage inlet connecting pipe (45) pressure Peco2 and low pressure compressor inlet pipe (17) air pressure is consistent, at this time meet Peci>Peco2, circulating exhaust gas unidirectional flow, realize exhaust gas recirculation; S4, high speed working condition of engine (1), high-low pressure stage exhaust regulating valve (37) is full open state, at this time engine (1) exhaust gas through full open high-low pressure stage exhaust regulating valve (37) into low pressure stage turbocharger (24), low pressure stage turbocharger (24) will be as the main engine (1) supercharging device work, at this time EGR drive valve (40) inlet pressure Peci and low pressure turbine inlet pipe (25) in the pressure same, also same with engine exhaust pipe (34) in the pressure, all for engine (1) exhaust pressure P under this condition, in order to guarantee the smooth transmission of circulating gas, at this time, EGR reversing valve (43) will connect EGR reversing valve low pressure stage inlet connecting pipe (44), circulating gas and low pressure compressor inlet pipe (17) connection, at this time, EGR reversing valve low pressure stage inlet connecting pipe (44) pressure Peco1 and low pressure compressor inlet pipe (17) pressure same, at this time meet Peci>Peco1, circulating exhaust gas unidirectional flow, realize exhaust gas recirculation; S5, in the medium speed working condition of the engine (1), the high-low pressure stage exhaust regulating valve (37) is in the flow regulating state, realizing the control of different openings, at this time, the high temperature and high pressure exhaust gas of the engine (1) enters the exhaust regulating valve inlet pipe (28) through the exhaust pipe (34) and flows under the control of the high-low pressure stage exhaust regulating valve (37), at this time, the inlet pressure of the exhaust regulating valve inlet pipe (28) is the same as the pressure of the high pressure turbine inlet pipe (29) and the pressure of the EGR drive valve inlet pipe (39), and the inlet pressure Peci of the EGR drive valve (40) is the pressure Pt in the engine exhaust pipe (34), in the adjustment process, the pressure in the exhaust regulating valve outlet pipe (38) is lower than the pressure in the exhaust regulating valve inlet pipe (28), the pressure difference of this part is the same as the pressure difference in the pipeline before and after the high pressure stage turbocharger (30), the high pressure stage turbocharger (30) also participates in part of the supercharging work, part of the exhaust gas flowing out of the high pressure turbine outlet pipe (60) and the exhaust gas flowing in the exhaust regulating valve outlet pipe (38) are collected through the low pressure turbine inlet pipe (25) and then enter the low pressure stage turbocharger (24) to drive the low pressure stage turbocharger (24) to work, under the control of the high-low pressure stage exhaust regulating valve (37), the high pressure stage turbocharger (30) and the low pressure stage turbocharger (24) work together to realize the compression of air, the inlet pressure Peci of the EGR drive valve (40) is the same as the pressure Pt in the engine exhaust pipe (34), the circulating gas unidirectionally flows in the EGR drive valve outlet pipe (41) and the EGR valve, cools down and then enters the EGR reversing valve (43), the EGR reversing valve (43) preferentially connects the EGR reversing valve high pressure stage inlet connecting pipe (45), at this time, the pressure of the EGR reversing valve high pressure stage inlet connecting pipe (45) is Peco2, and Peci>Peco2, the circulating exhaust gas unidirectionally flows to realize the exhaust gas recirculation.

10. The control method of a drive device of an exhaust gas recirculation system according to claim 9, characterized by Further comprising the following steps: S6, the circulating gas is sucked from the EGR supercharger compressor inlet (49) of the EGR drive supercharger (46), compressed and then flows out from the EGR supercharger compressor outlet (48), at this time, the pressure is further increased, after the control of the EGR reversing valve (43), the small circulating flow enters the high pressure stage turbocharger (30) through the EGR reversing valve high pressure stage inlet connecting pipe (45), the large circulating flow enters the low pressure stage turbocharger (24) through the EGR reversing valve low pressure stage inlet connecting pipe (44), the circulating gas pressures Peco2 and Peco1 entering the EGR reversing valve high pressure stage inlet connecting pipe (45) and the EGR reversing valve low pressure stage inlet connecting pipe (44) are further amplified under the action of the EGR drive supercharger (46) and are all greater than the pressure in the engine inlet pipe (3), providing greater exhaust gas recirculation driving pressure.

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