CN114458434B

CN114458434B - Atkinson cycle engine assembly with cooled EGR

Info

Publication number: CN114458434B
Application number: CN202210237394.7A
Authority: CN
Inventors: 潘圣临; 王建武; 曹权佐; 施玉春; 孙国媛; 王宏敏; 于晓彤; 刘锦杰; 桂智勇; 马南; 刘顺平; 刘宏华
Original assignee: Harbin Dongan Automotive Engine Manufacturing Co Ltd
Current assignee: Harbin Dongan Automotive Engine Manufacturing Co Ltd
Priority date: 2022-03-11
Filing date: 2022-03-11
Publication date: 2023-02-07
Anticipated expiration: 2042-03-11
Also published as: CN114458434A

Abstract

An Atkinson cycle engine assembly with cooled EGR belongs to the technical field of ignition engines with dosing mechanisms. A crank connecting rod mechanism, an ignition system, a gas distribution system, an air inlet system and an exhaust system are arranged in each engine cylinder; the gas distribution system adopts the Atkinson cycle technology, and the eccentric distance H between the piston axis of the crank connecting rod mechanism and the crankshaft axis is approximately equal to 9-11 mm. The invention adopts a combined mode of cooling EGR and Atkinson cycle to realize lower fuel consumption rate and higher engine power torque, and can maximally improve the engine torque by 30 percent. The cooler reduces the temperature of the exhaust gas, so that the amount of the exhaust gas and the EGR rate can be effectively increased, and the low-temperature exhaust gas contributes more to reducing oil consumption and emission when participating in combustion in the cylinder. The invention adopts the crankshaft offset technology, increases the Atkinson ratio under the condition of unchanged gas distribution phase, and also realizes lower fuel consumption rate.

Description

Atkinson cycle engine assembly with cooled EGR

Technical Field

The invention belongs to the technical field of ignition type engines with dosing mechanisms, and particularly relates to an Atkinson cycle engine assembly with cooled EGR.

Background

With the improvement of the living standard of people, the high-speed development of the automobile and internal combustion engine industry, the environmental protection awareness is intensified, and the oil consumption and emission regulations are continuously upgraded, so that the energy conservation and emission reduction become two major topics for the development of the internal combustion engine industry, and the pollution of the whole industry chain needs to be reduced from a source to a user, and the environment is protected.

In the aspect of energy saving, host plants at home and abroad are applied: the Otto cycle, atkinson cycle and Miller cycle technologies improve the combustion efficiency of the engine, improve the cold start oil consumption, reduce the pumping loss and the friction loss and improve the fuel economy of the gasoline engine by using the electronic supercharger technology and the high-pressure exhaust gas recirculation technology or the low-pressure high-pressure exhaust gas recirculation technology and the like.

The Atkinson cycle technology adopts an inlet valve late closing method, so that a larger physical compression ratio can be designed, the combustion efficiency is improved, and the pumping loss is reduced, so that the combustion efficiency is improved;

the turbocharging engine can make up for the reduction of air inflow brought by the air inlet reflux of the engine in the engine adopting the Atkinson cycle by improving the air inlet pressure of the engine, thereby improving the power torque of the engine.

The cooling EGR technology is matched with the supercharging technology for use, tail gas is taken from exhaust as required and enters an air intake system again after being cooled, pumping loss is reduced, and knocking is improved, so that the Atkinson cycle engine assembly with the cooling EGR is an important technology inevitably developed in the internal combustion engine industry, and is an important measure for protecting the blue sky.

At present, however, the torque drop is about 10% at the same displacement using deep atkinson technology. It is necessary to use a reasonable atkinson ratio, and to use cooled EGR and turbocharging techniques to compensate for the loss of power torque.

Therefore, it is an urgent technical problem to provide an atkinson cycle engine assembly with cooled EGR that can improve engine torque.

Disclosure of Invention

The present invention has been made to solve the above problems occurring in the prior art, and an atkinson cycle engine assembly with a cooled EGR;

the technical scheme adopted by the invention is as follows:

the Atkinson cycle engine assembly with the cooling EGR is characterized in that a crank connecting rod mechanism, an ignition system, a gas distribution system, an air inlet system and an exhaust system are arranged in each engine cylinder; the air distribution system adopts an Atkinson cycle technology, the eccentric distance H between the axis of a piston of the crank connecting rod mechanism and the axis of a crankshaft is approximately equal to 9-11 mm, and the cooling system of the Atkinson cycle engine assembly with the cooled EGR comprises a large water channel cycle and a small water channel cycle; the water path small circulation comprises a warm air pipeline, a transmission oil cooler, a water path tee joint I, an EGR cooler, an engine oil cooler, a water path tee joint II, a water inlet pipe assembly, a water pump assembly, a cylinder body cooling device and a cylinder cover cooling device; the water pump assembly is connected with the water inlet pipe assembly, the transmission oil cooler, the EGR cooler and the engine oil cooler, the water pump assembly adopts a mechanical water pump or electronic water pump technology, the cylinder body cooling and the cylinder cover cooling are both connected with the water pump assembly, the cylinder body cooling and the cylinder cover cooling are connected, the water pump assembly is responsible for pumping low-temperature water, the cylinder body cooling and the cylinder cover cooling adopt a layered cooling mode, and cooling liquid cooled by the cylinder body is finally cooled by the cylinder cover and flows to the thermal management module with the cooling liquid in the cylinder cover cooling;

the heat management module comprises an outlet I, an outlet II, an outlet III and an electronic thermostat; the cooling liquid absorbing heat through combustion of the engine cylinder is distributed to a downstream pipeline through an outlet I, an outlet II, an outlet III and an electronic thermostat; the first outlet is connected with an engine oil cooler and is responsible for cooling engine oil; the second outlet is connected with the EGR cooler and the transmission oil cooler respectively and is responsible for cooling the EGR cooler and the transmission oil cooler; the cooling liquid passing through the transmission oil cooler, the EGR and the engine oil cooler finally enters the water pump assembly.

Further, the air inlet system adopts a low-pressure cooling EGR system, and the exhaust system adopts a turbocharger; the low-pressure cooling EGR system comprises an exhaust gas pipeline, an air inlet pipeline, an EGR valve, an EGR cooler, an EGR differential pressure sensor, an EGR temperature sensor and a mixing valve; the air inlet end of the exhaust gas pipeline is connected with the air outlet end of the air inlet pipeline, the air outlet end of the exhaust gas pipeline is connected with the air inlet end of the air inlet pipeline, the turbocharger and the three-way catalyst are installed on the air inlet pipeline and located between two ends of the exhaust gas pipeline, the EGR cooler is installed on the exhaust gas pipeline, an EGR valve is arranged between the EGR cooler and the air outlet end of the exhaust gas pipeline, an air filter is installed on an inlet of the air inlet pipeline, EGR waste gas exhausted by the engine cylinder through the turbocharger is taken from the three-way catalyst, high-temperature waste gas enters the EGR cooler through the exhaust gas pipeline, the EGR cooler exchanges heat with the high-temperature waste gas, and the gas after heat exchange is mixed with fresh air before entering the turbocharger through the EGR valve.

Furthermore, an EGR temperature sensor is arranged in front of the EGR valve in the air inlet direction of the exhaust pipeline and used for measuring the temperature entering the EGR valve, pressure measuring points are arranged in front of and behind the EGR valve, the pressure difference between the front of the EGR valve and the rear of the EGR valve is calculated by the EGR pressure difference sensor, and the opening degree of the EGR valve is controlled in an auxiliary mode.

Further, an air mass flow meter and a mixing valve are sequentially arranged on the air inlet pipeline between the air filter and the exhaust end of the exhaust pipeline, and the flow of fresh air entering an EGR mixing point is controlled by the mixing valve through the opening degree.

Further, the waterway large circulation comprises a radiator assembly, a liquid supplementing kettle and an expansion kettle; the outlet of the radiator assembly and the outlet of the liquid supplementing kettle are both connected with the inlet of the water inlet pipe assembly, the expansion kettle is connected with the liquid supplementing kettle, and the outlet of the radiator assembly and the outlet of the heat management module are both communicated with the inlet of the expansion kettle.

Furthermore, an electronic thermostat is mounted on a pipeline between the thermal management module and the radiator assembly, and the electronic thermostat is responsible for whether the engine major cycle is developed or not and the depth of the major cycle.

Compared with the prior art, the invention has the following beneficial effects:

1) The invention adopts a combined mode of cooling EGR and Atkinson cycle to realize lower fuel consumption rate and higher engine power torque, and can maximally improve the engine torque by 30 percent. The cooler reduces the temperature of the exhaust gas, so that the amount of the exhaust gas and the EGR rate can be effectively increased, and the low-temperature exhaust gas contributes more to reducing oil consumption and emission when participating in combustion in the cylinder.

2) The invention adopts the crankshaft offset technology, increases the Atkinson ratio under the condition of unchanged gas distribution phase, and also realizes lower fuel consumption rate. The offset is 9mm, in this offset range, can reduce the acting stroke effectively and act on the side force of the piston, and then reduce the piston to the cylinder side force, thus make the energy consumed because of friction between cylinder wall and the piston also can reduce correspondingly, not only has improved the thermal efficiency of the internal-combustion engine, can lengthen the practical life of cylinder and piston, meanwhile, because of the offset setting of the bent axle, cause the piston stroke to increase, the piston acting time lengthens, favorable to the abundant burning of the fuel, can obtain more useful work under the same combustion condition, thus improve the fuel economy, improve the overall performance of the engine.

3) According to the invention, through the structural design, the waterway structure is optimized, the structure is more compact in a limited space, and the flow direction and the flow of the cooling liquid can be effectively adjusted according to the working condition of the engine by arranging the thermal management module, so that the engine is ensured to be at a proper working temperature, the performance of the engine is further improved to a certain extent, and the energy consumption of the engine is reduced.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic view of the cooling system of the present invention;

FIG. 3 is a schematic top dead center piston of the crank-link mechanism of the present invention;

FIG. 4 is a schematic illustration of the cooled EGR rate control logic of the present invention;

FIG. 5 is a schematic illustration of the invention P-V;

FIG. 6 is a valve timing diagram;

wherein: 1. an exhaust camshaft phaser; 2. an ignition coil; 3. an intake camshaft phaser; 4. an intake camshaft position sensor; 5. an intake valve; 10. an intercooler; 12. an EGR mixing point; 13. air filtering; 14. an air mass flow meter; 15. a mixing valve; 16. an EGR differential pressure sensor; 17. an EGR valve; 18. an EGR temperature sensor; 19. an EGR cooler; 20. a turbocharger; 21. a three-way catalyst; 23. a spark plug; 24. an exhaust camshaft position sensor; 25. an exhaust valve; 31. a heat sink assembly; 32. a water inlet pipe assembly; 33. a water pump assembly; 34. cooling the cylinder body; 35. cooling the cylinder cover; 36. a liquid replenishing kettle; 37. an expansion kettle; 38. a thermal management module; 39. an outlet I; 40. an outlet II; 41. an outlet III; 42. an electronic thermostat; 43. a warm air pipeline; 44. a transmission oil cooler; 45. the waterway tee I; 47. an oil cooler; 48. a waterway tee joint II; 51. a piston; 52. a connecting rod; 53. a crankshaft.

Detailed Description

For a better understanding of the objects, structure and function of the invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings.

The engine is schematically shown in FIG. 1.

A crank connecting rod mechanism, a gas distribution system, an ignition system, an air inlet system and an exhaust system are arranged in each engine cylinder;

as shown in FIG. 3, the crank-connecting rod mechanism comprises a crankshaft 53, a connecting rod 52, a piston 51 and other parts, and adopts an eccentric configuration, and the crankshaft offset technology means that the center of the crankshaft does not intersect with the center line of the piston, namely the eccentric distance H between the axis of the piston 51 and the axis of the crankshaft 53 is approximately equal to 9-11 mm.

The engine duty cycle is four-stroke, which includes an intake stroke, a compression stroke, a power stroke, and an exhaust stroke.

In the process of an intake stroke, a piston moves from a top dead center to a bottom dead center, an intake valve is opened, the pressure in a combustion chamber is reduced, air and fuel (or oil-gas mixture) are sucked into a cylinder, and at the moment, the piston applies work to the gas. The descending speed of the air inlet stroke piston is low, so that the inflation efficiency is reduced, but the descending time is long, so that the inflation efficiency can be improved due to long inflation time. And the adverse effect of slow descending of the piston in the air inlet stroke is compensated by matching with a supercharging technology.

The crankshaft offset technology is adopted, and in the process of a compression stroke, a piston moves from a bottom dead center to a top dead center to promote oil-gas mixing and compress oil-gas mixed gas. The upward process speed of the compression stroke piston is faster than that of a central type. The tangential force has little difference and the power consumption is basically unchanged. The faster the piston movement speed, the less the leakage, the heat loss and the combustible gas loss are reduced, and the maximum temperature, the maximum pressure and the heat efficiency of circulation are favorably improved.

In the working stroke process, the piston moves from the top dead center to the bottom dead center, mixed gas is combusted and releases heat under spark ignition, fuel is combusted and releases a large amount of heat to push the piston to move downwards, and the piston applies work outwards through the crankshaft.

The work stroke increases the piston stroke, which leads to the increase of the cylinder displacement and the improvement of the compression ratio. The final temperature and pressure of compression are higher, and the cycle thermal efficiency and average pressure are improved. The working stroke time is prolonged, which is beneficial to the full combustion of fuel, and more useful work can be obtained under the same combustion condition. The piston stroke increases. It is also possible to recover the power of the internal combustion engine used at the plateau, improving the power performance and the economical performance in the case where the combustion deteriorates due to the decrease in the intake air density.

The crank shaft biasing technology increases the Atkinson ratio under the condition of unchanged gas distribution phase;

the air distribution system comprises an electronic air inlet VVT, an electronic exhaust VVT, an air inlet valve, an exhaust valve and other parts, and the electronic air inlet VVT and the electronic exhaust VVT can adjust the phases of an air inlet camshaft and an exhaust camshaft in real time according to electric signals; the gas distribution system adopts an Atkinson cycle technology;

the Atkinson ratio is the effective expansion ratio divided by the effective compression ratio, and the Atkinson cycle depth is described by the Atkinson ratio; the Atkinson ratio is maximum at the moment that the exhaust valve is opened at the latest and the intake valve is closed at the latest;

the Atkinson engine with the cooled EGR has the design compression ratio of 11.5, the Atkinson ratio of 1.4-2.0 and the valve profile wrap angle of 250 CA.

In the embodiment, the engine adopts a combination mode of an Atkinson cycle and an EGR technology, the valve timing is adjusted through a conventional valve timing mechanism, the late closing of an intake valve is realized, the intake backflow is realized through the late closing of the intake valve to reduce the actual compression ratio of the engine, the Atkinson cycle is realized, the Atkinson ratio is 1.4, and the fuel consumption rate of the engine can be reduced. The cooler is used for reducing the temperature of the exhaust gas, so that the amount of the exhaust gas and the EGR rate can be effectively increased, the oil consumption is further reduced when the low-temperature exhaust gas participates in the combustion in the cylinder, and the contribution to the emission is larger.

The ignition system comprises an ignition coil 2 and a spark plug 23, wherein the ignition coil 2 transfers energy to the spark plug 23, and the spark plug 23 discharges to ignite the mixture; the ignition coil adopts a high-energy ignition coil, and the misfire rate is reduced.

The air distribution system comprises an intake valve 5, an exhaust valve 25, an intake camshaft phaser 3, an exhaust camshaft phaser 1, a camshaft, a spring and other parts, wherein the intake camshaft phaser 3 and the exhaust camshaft phaser 1 adopt electronic phasers and are provided with an intake camshaft position sensor 4 and an exhaust camshaft position sensor 24, the phase positions are monitored in real time, and the electronic phasers adjust the phase angles at any time according to the input of an ECU; the adjustment range is shown in fig. 6:

the air intake system adopts a low-pressure cooling EGR system, an EGR cooler takes air from the three-way catalytic converter, and high-temperature waste gas is cooled by the EGR cooler and then enters the air intake system of the engine through an EGR valve. The amount of exhaust gas entering the intake system is determined by the EGR valve opening. The exhaust system employs a turbocharger 20.

The air intake system includes a first passage and a second passage; the atmosphere is connected with the first channel and selectively communicated with fluid, and the second channel is communicated with the exhaust gas after the three catalysts.

The low-pressure cooling EGR system comprises an exhaust gas pipeline, an air inlet pipeline, an exhaust pipeline, an EGR valve 17, an EGR cooler 19, an EGR differential pressure sensor 16, an EGR temperature sensor 18, a mixing valve 15 and the like;

the inlet end of exhaust gas line is connected with the exhaust end of exhaust pipe, and the exhaust end of exhaust gas line is connected with the inlet end of inlet pipe, turbo charger 20 and three way catalyst converter 21 are all installed on exhaust pipe and are located between the exhaust gas line both ends, install EGR cooler 19 on the exhaust gas line to set up EGR valve 17 between EGR cooler 19 and exhaust gas line's exhaust end, install air filter 13 in the import of inlet pipe air filter 13 and the exhaust gas line install air mass flow meter 14 and mixing valve 15 on the inlet pipe between the exhaust end of exhaust gas line in proper order.

The engine cylinder takes gas from the three-way catalyst 21 through EGR waste gas discharged by the turbocharger 20, high-temperature waste gas enters the EGR cooler 19 through a waste gas pipeline, the EGR cooler 19 carries out heat exchange on the high-temperature waste gas, and the gas after heat exchange enters the turbocharger 20 before a compressor through the EGR valve 17 and is mixed with fresh air before the air filter 13 enters the compressor;

the cooling EGR assembly, through the reduction of 19 to exhaust gas temperature of cooler, can effectively increase exhaust gas volume and EGR rate, low temperature waste gas is bigger to reducing oil consumption, emission contribution when participating in the jar internal combustion, through to structural design, optimizes inlet tube structure, directly gets water through the integrated water pipe of cooler, has removed the harmful risk of heat that the application rubber tube brought from. The turbocharging engine can make up for the reduction of air inflow brought by the air inlet reflux of the engine in the engine adopting the Atkinson cycle by improving the air inlet pressure of the engine, thereby improving the power torque of the engine. And the air input of the engine in the prior art is insufficient, so that the power of the Atkinson engine is smaller than that of an Otto cycle engine with the same displacement.

An EGR temperature sensor 18 is arranged in front of the EGR valve 17 in the air inlet direction of the exhaust pipeline and used for measuring the temperature entering the EGR valve 17, pressure measuring points are arranged in front of and behind the EGR valve 17, the pressure difference between the front and the back of the EGR valve 17 is calculated by an EGR pressure difference sensor 16, and the opening degree of the EGR valve 17 is further assisted to be controlled;

when the exhaust gas pressure is low, in order to ensure the EGR rate, the mixing valve 15 controls the flow of fresh air entering the EGR mixing point 12 through the opening degree, and the EGR rate is ensured;

mixing fresh air and waste gas, and then entering an intercooler 10 through a pressure end of a turbocharger 20 to cool the gas;

the cooling system comprises a waterway large circulation part and a waterway small circulation part, wherein a solid black line is a small circulation waterway, and a space line is a large circulation waterway;

the water circulation structure is provided with two circulation water paths, the flow of water in the water circulation structure can be adjusted adaptively according to the state of the engine, and the cooling effect of the engine in a high-speed running state is ensured. Through the arrangement, the engine is ensured to work in a proper temperature range, and the maximum performance of the engine is favorably exerted. In the prior art, temperature control has errors, so that adjustment according to requirements cannot be realized, and the performance of the engine is reduced to a certain extent.

The water path small circulation comprises a warm air pipeline 43, a transmission oil cooler 44, a water path tee joint I45, an EGR cooler 19, an engine oil cooler 47, a water path tee joint II 48, a water inlet pipe assembly 32, a water pump assembly 33, cylinder body cooling 34, cylinder cover cooling 35 and the like;

the water pump assembly 33 is connected with the water inlet pipe assembly 32, the transmission oil cooler 44, the EGR cooler 19 and the engine oil cooler 47, the cooling liquid of the water inlet pipe assembly 32, the transmission oil cooler 44, the EGR cooler 19 and the engine oil cooler 47 flows through the water pump assembly 33, and the water pump assembly 33 adopts a mechanical water pump or an electronic water pump technology.

The cylinder body cooling 34 and the cylinder cover cooling 35 are both connected with the water pump assembly 33, the cylinder body cooling 34 is connected with the cylinder cover cooling 35, cooling liquid of the cylinder body cooling 34 and the cylinder cover cooling 35 is low-temperature water pumped by the water pump assembly 33, the cylinder body cooling 34 and the cylinder cover cooling 35 adopt a layered cooling mode, and the cooling liquid of the cylinder body cooling 34 finally flows through the cylinder cover cooling 35 and flows into the thermal management module 38 together with the cooling liquid in the cylinder cover cooling 35.

The thermal management module 38 includes a first outlet 39, a second outlet 40, a third outlet 41, an electronic thermostat 42, and so on. The cooling liquid absorbing heat through combustion of the engine cylinder is distributed to a downstream pipeline through a first outlet 39, a second outlet 40, a third outlet 41 and an electronic thermostat 42;

the first outlet 39 is connected with an engine oil cooler 47 and is responsible for cooling the engine oil;

the second outlet 38 is respectively connected with the EGR cooler 19 and the transmission oil cooler 44 and is responsible for cooling the EGR cooler 19 and the transmission oil cooler 44; the cooling liquid passing through the transmission oil cooler 44, the EGR cooler 19 and the engine oil cooler 47 finally enters the water pump assembly 33, and belongs to a part of a small circulation water path of the engine;

the waterway large circulation comprises a radiator assembly 31, a liquid supplementing kettle 36 and an expansion kettle 37; the outlet of the radiator assembly 31 and the outlet of the liquid supplementing kettle 36 are both connected with the inlet of the water inlet pipe assembly 32, the expansion kettle 37 is connected with the liquid supplementing kettle 36, and the outlet of the radiator assembly 31 and the outlet of the heat management module 38 are both communicated with the inlet of the expansion kettle 37.

An electronic thermostat 42 is installed on a pipeline between the thermal management module 38 and the radiator assembly 31, the electronic thermostat 42 is responsible for whether the engine large circulation and the depth of the large circulation are developed, and when the electronic thermostat is started, high-temperature cooling liquid from the cylinder body cooling 34 and the cylinder cover cooling 35 flows into the radiator assembly 31 through the electronic thermostat 42 to exchange heat with the high-temperature cooling liquid.

The crankshaft offset is shown in fig. 3, and when the top dead center or the bottom dead center is reached, the eccentric distance H between the axis of the piston 51 and the axis of the crankshaft 53 is approximately equal to 9-11 mm.

The EGR rate demand and control concept are shown in FIG. 4;

the whole vehicle inputs the torque demand to an ECU, the ECU calculates the air inflow (including fresh air quantity and EGR mass), the EGR mass is calculated, and the EGR rate is calculated through the pressure difference and the temperature before and after the EGR so as to further calculate the EGR mass flow;

after the position of the EGR valve is determined, the opening degree of the valve is adjusted in real time through the pressure sensor and the temperature sensor to meet the mass flow of the EGR, so that the requirement of the EGR rate is met, and the control of the engine on the EGR is met.

The difference between the atkinson cycle in the intake, compression, power, exhaust stroke and the otto cycle is shown in fig. 5.

It is to be understood that the present invention has been described with reference to certain embodiments, and that various changes in the features and embodiments, or equivalent substitutions may be made therein by those skilled in the art without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. An Atkinson cycle engine assembly with cooling EGR is characterized in that a crank link mechanism, an ignition system, a gas distribution system, an air inlet system and an exhaust system are arranged in each engine cylinder; the method is characterized in that: the air distribution system adopts an Atkinson cycle technology, the eccentric distance H between the axis of a piston (51) of the crank link mechanism and the axis of a crankshaft (53) is approximately equal to 9-11 mm, and the cooling system of the Atkinson cycle engine assembly with the cooled EGR comprises a large water channel cycle and a small water channel cycle;

the water path small circulation comprises a warm air pipeline (43), a transmission oil cooler (44), a water path tee joint I (45), an EGR cooler (19), an oil cooler (47), a water path tee joint II (48), a water inlet pipe assembly (32), a water pump assembly (33), a cylinder body cooling (34) and a cylinder cover cooling (35);

the water pump assembly (33) is connected with the water inlet pipe assembly (32), the transmission oil cooler (44), the EGR cooler (19) and the engine oil cooler (47), the water pump assembly (33) adopts the mechanical water pump or electronic water pump technology,

the cylinder body cooling (34) and the cylinder cover cooling (35) are both connected with the water pump assembly (33), the cylinder body cooling (34) is connected with the cylinder cover cooling (35), the water pump assembly (33) is used for pumping low-temperature water, the cylinder body cooling (34) and the cylinder cover cooling (35) adopt a layered cooling mode, and cooling liquid of the cylinder body cooling (34) finally flows into the thermal management module (38) through the cylinder cover cooling (35) and flows into the thermal management module (38) together with the cooling liquid in the cylinder cover cooling (35);

the thermal management module (38) comprises a first outlet (39), a second outlet (40), a third outlet (41) and an electronic thermostat (42);

the cooling liquid absorbing heat through combustion of the engine cylinder is distributed to a downstream pipeline through a first outlet (39), a second outlet (40), a third outlet (41) and an electronic thermostat (42);

the first outlet (39) is connected with an engine oil cooler (47) and is responsible for cooling engine oil;

the second outlet (40) is respectively connected with the EGR cooler (19) and the transmission oil cooler (44) and is responsible for cooling the EGR cooler (19) and the transmission oil cooler (44); the cooling liquid passing through the transmission oil cooler (44), the EGR cooler (19) and the engine oil cooler (47) finally enters the water pump assembly (33).

2. An Atkinson cycle engine assembly with cooled EGR as claimed in claim 1, wherein: the air inlet system adopts a low-pressure cooling EGR system, and the exhaust system adopts a turbocharger (20);

the low-pressure cooling EGR system comprises an exhaust gas pipeline, an air inlet pipeline, an exhaust pipeline, an EGR valve (17), an EGR cooler (19), an EGR differential pressure sensor (16), an EGR temperature sensor (18) and a mixing valve (15);

the inlet end of exhaust gas line is connected with the exhaust end of exhaust pipe, and the exhaust end of exhaust gas line is connected with the inlet end of inlet gas line, turbo charger (20) and three way catalyst converter (21) are all installed on the exhaust pipe and are located between the exhaust gas line both ends, install EGR cooler (19) on the exhaust gas line to set up EGR valve (17) between the exhaust end of EGR cooler (19) and exhaust gas line, install air filter (13) on the import of inlet gas line, engine cylinder gets gas from three way catalyst converter (21) through turbo charger (20) exhaust EGR waste gas, high temperature waste gas gets into EGR cooler (19) through the exhaust gas line, EGR cooler (19) carry out the heat exchange to high temperature waste gas, gas after the heat exchange gets into before turbo charger (20) compressor through EGR valve (17), mix with air filter (13) the fresh air that gets into before the compressor.

3. An Atkinson cycle engine assembly with cooled EGR as claimed in claim 2, wherein: an EGR temperature sensor (18) is arranged in front of the EGR valve (17) in the air inlet direction of the exhaust pipeline and used for measuring the temperature entering the EGR valve (17), pressure measuring points are arranged in front of and behind the EGR valve (17), the pressure difference between the front of and behind the EGR valve (17) is calculated by an EGR pressure difference sensor (16), and the opening degree of the EGR valve (17) is further assisted to be controlled.

4. An Atkinson cycle engine assembly with cooled EGR as claimed in claim 3, wherein: an air mass flow meter (14) and a mixing valve (15) are sequentially arranged on an air inlet pipeline between the air filter (13) and the exhaust end of the exhaust pipeline, and the flow of fresh air entering an EGR mixing point (12) is controlled by the mixing valve (15) through opening.

5. An Atkinson cycle engine assembly with cooled EGR as claimed in claim 1, wherein: the waterway large circulation comprises a radiator assembly (31), a liquid supplementing kettle (36) and an expansion kettle (37); the outlet of the radiator assembly (31) and the outlet of the liquid supplementing kettle (36) are both connected with the inlet of the water inlet pipe assembly (32), the expansion kettle (37) is connected with the liquid supplementing kettle (36), and the outlet of the radiator assembly (31) and the outlet of the heat management module (38) are both communicated with the inlet of the expansion kettle (37).

6. An Atkinson cycle engine assembly with cooled EGR as claimed in claim 2, wherein: an electronic thermostat (42) is mounted on a pipeline between the thermal management module (38) and the radiator assembly (31), and the electronic thermostat (42) is responsible for whether the engine major cycle is developed or not and the depth of the major cycle.

7. An Atkinson cycle engine assembly with cooled EGR as claimed in claim 6, wherein: the Atkinson engine is designed with a compression ratio of 11.5, an Atkinson ratio of 1.4-2.0 and a valve profile wrap angle of 250 CA.