CN203532106U

CN203532106U - Pure oxygen engine

Info

Publication number: CN203532106U
Application number: CN201320747381.0U
Authority: CN
Inventors: 田维; 韩志强; 吴学舜; 邓猛
Original assignee: Xihua University
Current assignee: Xihua University
Priority date: 2013-11-22
Filing date: 2013-11-22
Publication date: 2014-04-09
Anticipated expiration: 2023-11-22

Abstract

The utility model discloses a pure oxygen engine. An intake header pipe is connected with four cylinders through intake manifolds, wherein one cylinder is connected with an exhaust pipe, and an exhaust back pressure sensor, an exhaust back pressure control valve and an oxygen concentration sensor are arranged on the exhaust pipe; other three cylinders are connected with an intercooler through an EGR (exhaust gas recirculation) system intake header pipe, an oxygen outlet of the intercooler is connected with the intake header pipe, a pressure sensor is arranged on the EGR system intake header pipe connected with the rear end of the exhaust pipe through a decompression pipe; a decompression valve is arranged on the decompression pipe; and a pressure sensor, a temperature sensor and a pure oxygen inlet are arranged on the intake header pipe. The pure oxygen engine adopts pure oxygen fuel and 75% of EGR mixture, so that the effects of saving energy, reducing emission and improving thermal efficiency and power of the engine are realized.

Description

Pure oxygen engine

Technical Field

The utility model belongs to the internal-combustion engine field, especially a piston pure oxygen engine.

Background

In recent years, environmental issues have been receiving attention from countries and general public people. The exhaust emission of automobiles is pushed to the foreground under the background of heavy pollution, and more strict emission regulations are put forward in all countries in the world. Especially in China, not only are stricter emission regulations put forward, but also measures such as limiting the operation area of vehicles with substandard emission and the like are implemented to relieve serious urban pollution. In order to reduce the emission of the automobile engine, a series of measures such as a charge-air cooling technology, an EGR technology, a high-pressure injection technology, an electronic control technology and the like are adopted by the engine researchers. These technologies alleviate the emission difficulties to some extent, but there are still many technical difficulties to solve the emission problems of the engine fundamentally. The emission of automobile engines (including diesel engines and gasoline engines) is mainly NOx, PM, HC and CO. Especially, PM emissions from diesel engines and GDI gasoline engines have a great influence on particulate matter in the air. Of all these emissions, NOx varies substantially in a reverse manner to the other three emissions, i.e. if the NOx emissions are reduced, the other three emissions, or one or two of them, tend to increase. It is therefore difficult to reduce the emissions of all emissions.

Research has shown that NOx is mainly due to N in air₂With O in the air₂Generated by oxidation reaction. If can convert N in the air₂The pure oxygen engine concept is proposed because no NOx is produced in the engine exhaust when all is removed. If the engine only takes in oxygen and stoichiometric combustion is carried out, abnormal phenomena such as overheating and the like of the engine inevitably occur; if the fuel is not combusted in stoichiometric ratio, the waste of oxygen is inevitable, and the pure oxygen is obtained at a cost. Therefore, the engine must feed in pure oxygen while adding other gases that do not react with oxygen and fuel. CO 2₂Exactly meet the requirements and obtain CO₂Very easy, the product after combustion is CO₂. Although CO is removed from the exhaust gas after combustion₂And also H₂O, but H at high temperature₂O is gaseous and does not react with oxygen and fuel, so that the exhaust gas of the engine can be directly introduced into the intake gas to be mixed with pure oxygen, the formed gas mixture is used as the working medium of the engine, and then the fuel with the corresponding proportion is injected to perform combustion work.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a pure oxygen engine adopts the mixture of pure oxygen fuel and 75% exhaust gas recirculation to admit air to realize the energy saving and emission reduction of engine.

The purpose of the utility model is realized like this: a pure oxygen engine comprises an air inlet main pipe which is respectively connected with air inlets of four cylinders through an air inlet manifold, an air outlet of one of the four cylinders is connected with an exhaust pipe, and an exhaust back pressure sensor, an exhaust back pressure control valve and an oxygen concentration sensor are sequentially arranged on the exhaust pipe along an exhaust direction; the exhaust ports of the rest three cylinders of the four cylinders are connected with the air inlet of an EGR intercooler through an EGR system air inlet main pipe, the air outlet of the EGR intercooler is connected with the air inlet main pipe through an EGR pipe, and an EGR pressure sensor is arranged on the EGR system air inlet main pipe; the air inlet main pipe is provided with a pure oxygen inlet, and the air inlet main pipe is provided with a pressure sensor and a temperature sensor; the EGR system intake manifold is connected to a portion of the exhaust pipe located downstream of the oxygen concentration sensor via a pressure release pipe to which an EGR pressure release valve is attached.

And signals of the pressure sensor, the temperature sensor, the exhaust back pressure sensor and the oxygen concentration sensor are output to the ECU, and control signals of the ECU are output to the exhaust back pressure control valve and the EGR pressure release valve.

And a cooling medium control valve is arranged on an inlet pipe of a cooling medium of the EGR intercooler, and a control signal of the ECU is output to the cooling medium control valve.

The utility model discloses piston pure oxygen engine advance, exhaust system structure and the combustion control scheme of engine. The engine can realize the mixed air intake of 75% Exhaust Gas Recirculation (EGR) and pure oxygen, and the engine can operate in the states of lean mixture, stoichiometric mixture and rich mixture to perform combustion and work according to the requirements of working conditions with the help of an electronic control system, so that the aims of saving energy, reducing emission, improving heat efficiency and improving power of the engine are fulfilled.

The utility model discloses piston pure oxygen engine, including four jar engines (also can be for the multi-cylinder engine of other quantity), pure oxygen air intake system, engine exhaust system, exhaust gas recirculation system (EGR system) and electronic control system (ECU).

The air intake system of the engine comprises an air intake manifold and an air intake manifold, wherein one end of the air intake manifold is connected with an engine cylinder, and the other end of the air intake manifold is connected with the air intake manifold. The air inlet manifold is also connected with an EGR system and a pure oxygen air inlet system, a temperature sensor and a pressure sensor are also arranged on the air inlet manifold, and signals of the temperature sensor and the pressure sensor are directly transmitted to an electronic control system (ECU).

The exhaust system of the engine comprises an exhaust pipe, a pressure sensor, a back pressure control valve and an oxygen concentration sensor are arranged on the exhaust pipe, signals of the temperature sensor and the oxygen concentration sensor are directly transmitted to the ECU, and the back pressure control valve receives control signals from the ECU. One end of the exhaust pipe is connected with one cylinder of the engine, and the other end of the exhaust pipe is directly communicated with the atmosphere.

The EGR system comprises an EGR system air inlet manifold, an EGR pressure sensor, an EGR intercooler and an EGR pressure release valve. One end of an EGR system air inlet manifold in the EGR system is connected with the other three cylinders of the engine, and the other end of the EGR system air inlet manifold is connected with the air inlet manifold of the engine through an EGR intercooler. The intercooler and the EGR purge valve receive signals from the ECU.

The utility model discloses a characteristics and beneficial effect do:

1. 3 of the 4 exhaust pipes are directly connected to the intake manifold, thereby achieving an EGR rate as high as 75%.

2. 3 of the 4 exhaust pipes are directly connected with an air inlet manifold, the pressure in the air inlet manifold can be close to 75% of the pressure of the exhaust pipe, and the air inlet manifold is equivalently supercharged relative to the atmospheric pressure, so that a supercharger is not required to be additionally installed, the structure is simplified, the cost is saved, and the heat efficiency of the engine can be improved.

3. 3 of 4 exhaust pipes are directly connected with an air inlet main pipe, 75% of exhaust gas enters a cylinder to be combusted again, and THC, CO, PM and other products which are not completely combusted in the exhaust gas can be combusted again to release heat, so that the aims of saving fuel and reducing emission are fulfilled.

4. 3 in the 4 blast pipes are directly connected with the air inlet main pipe, pure oxygen directly enters the air inlet main pipe through the air supply system, and the total mole number of air inlet and exhaust gas under each stable working condition is balanced, so that air quantity adjusting parts such as a throttle valve are not needed, the mechanism and pumping loss are simplified, the cost of the engine is reduced, and the efficiency of the engine is improved.

5. 3 of the 4 exhaust pipes are directly connected with an air inlet main pipe, and the exhaust gas actually exhausted into the air is only 25 percent of that of a common engine, so that the total emission of the engine can be greatly reduced; the exhaust gas waste heat discharged into the air actually is greatly reduced, the EGR retained waste heat heats the intake air, the heat is recycled, and the heat efficiency of the engine is improved.

6. No N is generated in the whole combustion process₂Thus, the problem of NOx emission can be thoroughly solved; on the basis, the combustion temperature of the engine can be properly increased, and THC, CO and PM emission can be reduced.

7. The utility model provides a combustion scheme under each stable operation condition, under the acceleration operating mode and the pure oxygen molar ratio under the deceleration operating mode all about 20.3%, is close with the oxygen content molar ratio in the middle of the air, therefore the pure oxygen engine can realize stable combustion process.

8. The exhaust system is provided with an exhaust back pressure adjusting device, and the residual exhaust gas coefficient in the cylinder directly exhausting the atmosphere can be ensured to be equal to that of the other 3 cylinders.

9. The EGR system is provided with a pressure release valve, and the oxygen molar ratio in a cylinder of the engine and the total gas amount in the cylinder are controlled by adjusting the EGR amount under the working conditions of rapid acceleration and rapid deceleration, so that the reliable operation of the engine is ensured.

10. The utility model discloses it is all suitable to the compression ignition engine that uses the diesel engine to represent and the spark-ignition engine that uses the gasoline engine to represent.

Drawings

Fig. 1 is a mechanism layout diagram of the pure oxygen engine of the present invention.

FIG. 2 is a block diagram of the operation principle of the pure oxygen engine of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

In fig. 1, an (engine) intake manifold 2, engine cylinders 3, an exhaust manifold 4, an exhaust back pressure sensor 5, an exhaust pipe 6, an EGR system intake manifold 7, an EGR pressure sensor 8, an exhaust back pressure control valve 9, an oxygen concentration sensor 10, an EGR pressure release valve 11, an EGR intercooler 12, an EGR pipe 13, an (intake manifold) temperature sensor 14, an (intake manifold) pressure sensor 15, and a pure oxygen intake port 16;

fig. 1 shows a pure oxygen engine, which comprises an intake manifold 1 connected with intake ports of four cylinders 3 through intake manifolds 2, respectively, and is characterized in that an exhaust port of one of the four cylinders 3 is connected with an exhaust pipe 6, and an exhaust back pressure sensor 5, an exhaust back pressure control valve 9 and an oxygen concentration sensor 10 are sequentially arranged on the exhaust pipe 6 along an exhaust direction; the exhaust ports of the rest three cylinders in the four cylinders 3 are connected with the air inlet of an EGR intercooler 12 through an EGR system air inlet manifold 7, the air outlet of the EGR intercooler 12 is connected with the air inlet manifold 1 through an EGR pipe 13, and an EGR pressure sensor 8 is arranged on the EGR system air inlet manifold 7; the air inlet main pipe 1 is provided with a pure oxygen inlet 16, and the air inlet main pipe 1 is provided with a pressure sensor 15 and a temperature sensor 14; the EGR system intake manifold 7 is connected to a portion of the exhaust pipe 6 downstream of the oxygen concentration sensor 10 via a pressure release pipe to which an EGR pressure release valve 11 is attached.

The pressure sensor 15, the temperature sensor 14, the exhaust back pressure sensor 5, and the oxygen concentration sensor 10 output signals to the ECU, and control signals of the ECU are output to the exhaust back pressure control valve 9 and the EGR relief valve 11.

A cooling medium control valve is arranged on an inlet pipe of a cooling medium of the EGR intercooler 12, and a control signal of the ECU is output to the cooling medium control valve.

An air inlet manifold 1 of the engine is connected with an air inlet manifold 2, a pure oxygen air inlet 16 and an EGR (exhaust gas recirculation) pipe 13, and the air inlet manifold of the engine is provided with an air inlet manifold temperature sensor 14 and an air inlet manifold pressure sensor 15;

the intake manifold 2 is connected with an intake manifold 1 of the engine and is also correspondingly connected with four cylinders 3 of the engine one by one;

one of the four (engine) cylinders 3 is connected with one end of an exhaust manifold 4, and the other three cylinders are connected with an EGR system intake manifold 7;

the other end of the exhaust manifold 4 is connected with one end of an exhaust pipe 6, and an exhaust back pressure sensor 5 is arranged on the exhaust manifold 4;

the other end of the exhaust pipe 6 is directly exhausted into the atmosphere, and an exhaust back pressure control valve 9 and an oxygen concentration sensor 10 are installed on the exhaust pipe 6;

an EGR pressure sensor 8 is installed on an EGR system air inlet manifold 7, one end of the EGR system air inlet manifold 7 is connected with the other three (engine) cylinders 3, the other end of the EGR system air inlet manifold 7 is connected with an exhaust pipe 6 through an EGR pressure release valve 11, the connection position is located at the downstream of an exhaust back pressure control valve 9 and an oxygen concentration sensor 10, and the other end of the EGR system air inlet manifold is connected with an EGR intercooler 12 (both a shell-and-tube heat exchanger or a plate heat exchanger and the like;

the other end of the EGR intercooler 12 is connected to the intake manifold via an EGR pipe 13.

In fig. 1, "in and out" of the EGR intercooler are shown as the inlet and outlet of the cooling medium, which may be inside the tubes of the shell and tube heat exchanger, and the cooled EGR gas outside (i.e., between the tubes).

The pressure signal of the exhaust back pressure sensor 5 is directly transmitted to the ECU, the signal of the EGR pressure sensor 8 is directly transmitted to the ECU, and the ECU controls an exhaust back pressure control valve 9 by comparing the pressure signal of the exhaust back pressure sensor 5 with the signal of the EGR pressure sensor 8, so that the residual exhaust gas coefficients in each of the four cylinders of the (engine) cylinder 3 are ensured to be equal.

The oxygen concentration sensor 10 is used to determine the state of the engine air-fuel mixture.

The EGR pressure release valve 11 is opened or closed according to the signal of the ECU, and the control of the EGR amount is realized.

The EGR intercooler 12 receives a signal from the ECU to control the temperature of the EGR gas according to the operating condition of the engine, thereby preventing overheating of the engine.

Signals of the (intake manifold) temperature sensor 14 and the (intake manifold) pressure sensor 15 are directly transmitted to the ECU as a basis for judging and controlling the EGR intercooler 12 (a cooling medium control valve is provided on an inlet pipe of a cooling medium of the EGR intercooler 12, and a control signal of the ECU is output to the cooling medium control valve) and the EGR pressure release valve and the exhaust back pressure control valve (signals of the pressure sensor 15, the temperature sensor 14, the exhaust back pressure sensor 5 and the oxygen concentration sensor 10 are output to the ECU, and a control signal of the ECU is output to the exhaust back pressure control valve 9 and the EGR pressure release valve 11).

The pure oxygen engine of the utility model works according to the following principle:

the exhaust gas from one of the 4-cylinder engines exits the engine directly into the atmosphere with an exhaust back pressure controlled by a back pressure control valve and consistent with the exhaust pressure of the remaining three cylinders (i.e., the pressure in the EGR system intake manifold). All the gas in the other three cylinders enters an engine air inlet manifold after passing through an EGR system air inlet manifold and an EGR intercooler, the temperature of the gas after the EGR intercooler is controlled according to the pressure and the temperature in the air inlet manifold, and H in the EGR gas after the intercooler₂O remains in a dry vapor state. The pure oxygen then directly enters into air intake manifold and EGR gas mixture through the pure oxygen import on the air intake manifold, and inside the gas mixture enters into the engine via air intake manifold, the air input of pure oxygen was controlled by ECU according to operating mode and the oxygen concentration sensor of installing on the blast pipe. The fuel quantity is controlled according to the air inflow and the working condition of the pure oxygen.

According to the working condition and the corresponding gas mixture state of the piston type internal combustion engine, the combustion mode of the pure oxygen engine is divided into a stoichiometric ratio combustion mode, a lean mixture combustion mode and a rich mixture combustion mode. Each combustion mode is distinguished according to the running condition of the engine, including a steady-state working condition, an acceleration working condition and a deceleration working condition, so that the combustion modes under 9 different working conditions are obtained, and the specific combustion mode is carried out according to the following processes:

1. stoichiometric combustion mode

Chemical formula under steady state condition:

wherein,

CO₂+0.9H₂o is the amount of EGR gas entering the cylinder;

the amount of pure oxygen entering the cylinder;

for the amount of fuel entering the cylinder, CH_1.8Is an equivalent molecular formula of the fuel;

the total product formed after combustion.

Under steady-state conditions, the gas will be totally exhausted

All the intake pipes are introduced with:

amount of EGR gas CO left of the chemical formula₂+0.9H₂O is equal, so the engine operation is balanced over the gases; in addition, the pure oxygen added and the fuel quantity entered can be completely combusted, so that the engine can be stably and continuously operated.

In this state, the molar percentage of pure oxygen to the total intake air was 20.3%.

Chemical formula under acceleration (deceleration) working condition:

wherein,

CO₂+0.9H₂o is the amount of EGR gas entering the cylinder;

the amount of pure oxygen entering the cylinder;

the total product formed after combustion.

Under acceleration (deceleration) conditions, the gas will be exhausted altogether

All the intake pipes are introduced with:

when x is greater than 0, the ratio of x,

amount of EGR gas CO larger than that on the left side of the original chemical formula₂+0.9H₂O, so that the quantity of working medium in the cylinder of the engine in the next cycle is increased, and simultaneously, the pure oxygen air inlet quantity and the corresponding quantity of fuel x (1.45O) are increased₂+CH_1.8) The balance of a working cycle on the engine is broken, the work capacity is increased, and therefore the engine is accelerated. After accelerating to the target rotation speed, x is made 0, and the engine returns to the stable operation state again. In this state, the mole percentage of pure oxygen to the total intake air is greater than 20.3%.

When x is less than 0, the first step is carried out,

less than the left EGR gas amount CO of the original chemical formula₂+0.9H₂O, the amount of working fluid in the cylinder of the next cycle is reduced, and simultaneously the working fluid is reducedPure oxygen intake air quantity and corresponding fuel x (1.45O) are reduced₂+CH_1.8) The balance of a working cycle on the engine is broken, the work capacity is weakened, and therefore the engine is decelerated. After the speed is reduced to the target speed, x is made to be 0, and the engine returns to the stable working state again. In this state, the mole percentage of pure oxygen to the total intake air is less than 20.3%.

2. In lean combustion mode (oxygen excess combustion mode)

Chemical formula under steady state working condition:

wherein,

defining alpha as the actual oxygen surplus coefficient of each working cycle, namely the coefficient of the additionally added oxygen;

definition, target oxygen excess coefficient

Then there are:

CO₂+0.9H₂o is the amount of EGR gas entering the cylinder;

the amount of pure oxygen entering the cylinder;

being virtually all products formed after combustion, alpha O₂Does not participate in the reaction.

Under steady-state conditions, the gas will be totally exhausted

All the intake pipes are introduced with:

amount of EGR gas CO greater than the left side of the chemical formula₂+0.9H₂O, after a plurality of cycles, the total exhaust will reach

Total amount of EGR reaches

The gas working medium of the engine reaches a new balance, namely:

wherein,

therefore, the working process of the engine can be balanced on gas; in addition, the added pure oxygen can ensure that the entered fuel quantity can be completely combusted, the heat released by the fuel in each cycle is the same, the work capacity of the engine is stable, and therefore the engine can stably and continuously run.

In this state, the mole percentage of pure oxygen in the whole intake air is more than 20.3%; the oxygen is in excess of the fuel, and belongs to a lean combustion mode.

Chemical formula under acceleration (deceleration) working condition:

wherein,

All the intake pipes are introduced with:

when x is greater than 0, the ratio of x,

amount of EGR gas larger than left side of original chemical formula

Therefore, the working medium amount in the cylinder of the next cycle engine is increased, and simultaneously, the pure oxygen air inflow and the corresponding amount of fuel x (1.45O) are increased₂+CH_1.8) The balance of a working cycle on the engine is broken, the work capacity is increased, and therefore the engine is accelerated. After accelerating to the target rotation speed, x is made 0, and the engine returns to the stable operation state again. In this state, pure oxygen accounts for the entire intake airThe mole percentage value of the (B) is more than 20.3 percent; the oxygen amount is excessive relative to the fuel, and the lean combustion belongs to.

When x is less than 0, the first step is carried out,

amount of EGR gas smaller than left side of original chemical formulaTherefore, the working medium amount in the cylinder of the next cycle engine is reduced, and simultaneously, the pure oxygen air inflow and the corresponding amount of fuel x (1.45O) are reduced₂+CH_1.8) The balance of a working cycle on the engine is broken, the work capacity is weakened, and therefore the engine is decelerated. After the speed is reduced to the target speed, x is made to be 0, and the engine returns to the stable working state again. In this state, the mole percentage of pure oxygen in the whole intake air is more than 20.3%; the oxygen amount is excessive relative to the fuel, and the lean combustion belongs to.

3. According to a rich gas combustion mode:

chemical formula under steady state working condition:

wherein,

defining beta as a fuel surplus coefficient of each working cycle, namely a coefficient of actually adding more fuel in each cycle relative to pure oxygen;

definition, target oxygen excess coefficient

Then there are:

CO₂+0.9H₂o is the amount of EGR gas entering the cylinder;

the amount of pure oxygen entering the cylinder;

beta CH being the total product formed after combustion_1.8(G) Is the vapor formed by the fuel at high temperature.

Under steady-state conditions, the gas will be totally exhaustedAll the intake pipes are introduced with:

amount of EGR gas CO greater than the left side of the chemical formula₂+0.9H₂And O. After a number of cycles, the formula will reach a new equilibrium,

at this time, the proportion of fuel vapor is small, and part of fuel is liquid, so that the working process of the engine is approximately balanced on gas; in addition, the added pure oxygen completely participates in the reaction, and the released heat is the same as the work-doing capacity, so that the engine can stably and continuously run.

In this state, the mole percentage of pure oxygen in all the intake air is less than 20.3%, and the fuel is excessive, which belongs to over-rich combustion.

Chemical formula under acceleration (deceleration) working condition:

wherein,

All the intake pipes are introduced with:

when x is greater than 0, the ratio of x,

amount of EGR gas larger than left side of original chemical formulaTherefore, the working medium amount in the cylinder of the next cycle engine is increased, and simultaneously, the pure oxygen air inflow and the corresponding amount of fuel x (1.45O) are increased₂+CH_1.8) The balance of a working cycle on the engine is broken, the work capacity is increased, and therefore the engine is accelerated. After accelerating to the target rotation speed, x is made 0, and the engine returns to the stable operation state again. In this state, the mole percentage of pure oxygen in the whole intake air is more than 20.3%; the oxygen quantity is relative to the fuel shortage, and belongs to an over-rich mixed gas combustion mode.

When x is less than 0, the first step is carried out,

amount of EGR gas smaller than left side of original chemical formula

Therefore, the working medium amount in the cylinder of the next cycle engine is reduced, and simultaneously, the pure oxygen air inflow and the corresponding amount of fuel x (1.45O) are reduced₂+CH_1.8) The balance of a working cycle on the engine is broken, the work capacity is weakened, and therefore the engine is decelerated. After the speed is reduced to the target speed, x is made to be 0, and the engine returns to the stable working state again. In this state, the mole percentage of pure oxygen in all the intake air is less than 20.3%; the oxygen quantity is relative to the fuel shortage, and belongs to an over-rich mixed gas combustion mode.

The working conditions of rapid acceleration and rapid deceleration are as follows:

and for the quick acceleration working condition, the gas quantity of the EGR is adjusted by adjusting the opening degree of the EGR pressure release valve, so that the molar ratio of pure oxygen in the mixed gas is controlled, and the engine is accelerated stably.

And for the condition of rapid deceleration, adjusting the gas quantity of the EGR by adjusting the opening degree of the EGR pressure release valve, thereby controlling the lean limit of the gas mixture and keeping the engine to decelerate stably.

The "residual exhaust gas coefficient" is a term of art for internal combustion engines and is defined above any of the specifications for internal combustion engines.

Claims

1. A pure oxygen engine comprises an air inlet main pipe (1) which is respectively connected with air inlets of four cylinders (3) through an air inlet manifold (2), and is characterized in that an air outlet of one cylinder in the four cylinders (3) is connected with an exhaust pipe (6), and an exhaust back pressure sensor (5), an exhaust back pressure control valve (9) and an oxygen concentration sensor (10) are sequentially arranged on the exhaust pipe (6) along the exhaust direction; the exhaust ports of the rest three cylinders in the four cylinders (3) are connected with the air inlet of an EGR intercooler (12) through an EGR system air inlet manifold (7), the air outlet of the EGR intercooler (12) is connected with an air inlet manifold (1) through an EGR pipe (13), and an EGR pressure sensor (8) is arranged on the EGR system air inlet manifold (7); a pure oxygen inlet (16) is formed in the air inlet main pipe (1), and a pressure sensor (15) and a temperature sensor (14) are arranged on the air inlet main pipe (1); the EGR system intake manifold (7) is connected to a portion of the exhaust pipe (6) located downstream of the oxygen concentration sensor (10) via a pressure relief pipe to which an EGR pressure relief valve (11) is attached.

2. The pure oxygen engine according to claim 1, further comprising an ECU; and signals of the pressure sensor (15), the temperature sensor (14), the exhaust back pressure sensor (5) and the oxygen concentration sensor (10) are output to the ECU, and control signals of the ECU are output to the exhaust back pressure control valve (9) and the EGR pressure release valve (11).

3. A pure oxygen engine according to claim 2 characterized in that a cooling medium control valve is arranged in the inlet pipe of the cooling medium of the EGR intercooler (12), and the control signal of the ECU is output to the cooling medium control valve.