A system and method for enabling and increasing engine EGR rate

Abstract

The application discloses a system and method for realizing and improving engine EGR rate, which comprises an ECU of an engine, an exhaust pipe and an air inlet pipe connected to the engine, the exhaust pipe and the air inlet pipe being connected to an EGR valve, and a mixed gas pipe being further connected to the EGR valve, wherein the ECU is provided with a pressure difference obtaining unit capable of obtaining a pressure difference, and the exhaust pipe is further provided with an electrically-controlled supercharging device capable of supercharging exhaust gas in the exhaust pipe. The system for realizing and improving engine EGR rate has the structure, when the obtained pressure difference W is less than or equal to zero, and the set value of the EGR rate under the current working condition in the storage unit is greater than zero, the electrically-controlled supercharging device is started to supercharge the exhaust gas until the actual value of the actual EGR rate is equal to the set value of the EGR rate under the current working condition. The application has the advantages that the intake pressure of the exhaust gas is adjusted in real time to ensure the proportion of the exhaust gas and fresh air, and the EGR rate of the engine and the performance of the engine are ensured in real time.

Description

TECHNICAL FIELD

[0001] The present application relates to a system and method for achieving and improving engine EGR rate. BACKGROUND

[0002] In order to control the carbon emission requirements of the engine, the EGR system (exhaust gas recirculation system) is used on the engine to mix the exhaust gas of the engine with fresh air and then enter the engine for combustion. In the prior art, an EGR valve is arranged in the EGR system, and by controlling the opening degree of the EGR valve, the proportion of the exhaust gas and the fresh air is controlled, so as to achieve a suitable EGR rate. In the prior art, the EGR rate can be calculated by using the flow method or the carbon dioxide method to detect the gas flow in the pipeline so as to calculate the EGR rate.

[0003] For example, in the Chinese invention patent with the patent application number 201711421078.0, an EGR rate control system is disclosed, which comprises a diesel engine system controller and an exhaust gas recirculation EGR system. The EGR system comprises an EGR cooler, an air compressor, a high-pressure gas cylinder, a second temperature and pressure sensor and an EGR valve connected in sequence through an exhaust gas inlet pipeline. The EGR cooler is connected with the gas outlet of the aftertreatment box, the gas outlet of the high-pressure gas cylinder is provided with a gas release valve, and the EGR valve is connected with the air inlet of the diesel engine. The controller is connected with the air flow meter, the first temperature and pressure sensor, the intake throttle valve, the EGR valve, the second temperature and pressure sensor, the gas release valve and the diesel engine. The control system can eliminate the dependence on the supercharger drive, thereby solving the problem of low EGR rate at the low speed section of the supercharger. The disadvantage is that under different working conditions, the pressure of the exhaust gas and the pressure of the fresh air are not the same, so it is difficult to ensure the EGR rate by only controlling the opening degree of the EGR valve. In the above invention, the structure of the gas cylinder is arranged to pressurize the exhaust gas (exhaust gas) and then enter the EGR valve, but the actual pressure value is not detected, and the exhaust gas is pressurized regardless of whether there is a demand for EGR rate under the current working condition. Not only does it cause waste of energy, but also it cannot be adjusted in real time, so there is a problem of unsatisfactory EGR rate control. SUMMARY

[0004] The first technical problem to be solved by the present application is to provide a system for achieving and improving engine EGR rate, which can pressurize the exhaust gas in real time according to whether there is a demand for EGR rate under the current working condition, so as to effectively ensure the EGR rate.

[0005] To solve the above technical problems, the system for realizing and improving the EGR rate of an engine is provided, which comprises an ECU of the engine, an exhaust pipe and an air inlet pipe connected to the engine, the exhaust pipe and the air inlet pipe are both connected to an EGR valve, and a mixed gas pipe is further connected to the EGR valve, characterized in that the ECU is provided with a differential pressure acquisition unit capable of acquiring the differential pressure between the front part of the EGR valve and the air inlet pipe, and the exhaust pipe is further provided with an electrically-controlled supercharging device capable of supercharging the exhaust gas in the exhaust pipe.

[0006] After the above structure is adopted, when the detected differential pressure value is less than or equal to zero, the engine cannot obtain the EGR rate or has a very low EGR rate even if the EGR valve has an opening degree, so the electrically-controlled supercharging device is started to supercharge the exhaust gas in real time, thereby ensuring the ratio of the exhaust gas and the fresh air and the EGR rate under the current working condition. The present application can be adjusted in real time according to the actual working condition, effectively saves the power resource and ensures the normal operation of the engine.

[0007] The electrically-controlled supercharging device comprises a turbocharger connected in parallel to the exhaust pipe, and an electromagnetic valve connected to the turbocharger and used for controlling whether the turbocharger is started, and the electromagnetic valve is electrically connected to the ECU of the engine.

[0008] The first pressure sensor is arranged on the exhaust pipe in front of the EGR valve, the second pressure sensor is arranged on the air inlet pipe in rear of the EGR valve, and the differential pressure acquisition unit is used for reading the values of the first pressure sensor and the second pressure sensor to obtain the differential pressure.

[0009] The pressure detection pipes are respectively arranged on the exhaust pipe in front of the EGR valve and the air inlet pipe in rear of the EGR valve, the ends of the two pressure detection pipes are connected to a differential pressure sensor, and the differential pressure sensor is electrically connected to the differential pressure acquisition unit of the ECU.

[0010] The ECU of the engine is provided with a storage unit pre-stored with the EGR rate value under the preset working condition.

[0011] The exhaust pipe is connected in parallel to a branch pipe, a three-way valve is arranged at the position where the exhaust pipe is initially connected in parallel to the branch pipe, and the three-way valve is electrically connected to the ECU.

[0012] The turbocharger is a turbocharger connected to the exhaust pipe.

[0013] The second technical problem solved by the present application is a method for realizing and improving the EGR rate of an engine, characterized in that the system for realizing and improving the EGR rate of an engine is adopted.

[0014] S1, the ECU differential pressure acquisition unit of the engine acquires the differential pressure between the exhaust pipe before the EGR valve and the air intake pipe after the EGR valve in real time, and obtains the differential pressure value W; the acquisition unit of the ECU acquires the actual EGR rate;

[0015] S2, when the acquired differential pressure value W is less than or equal to zero, and the set value of the EGR rate in the current working condition in the storage unit is greater than zero, the electrically controlled supercharging device is started to supercharge the exhaust gas until the actual value of the actual EGR rate is equal to the set value of the EGR rate in the current working condition; when the acquired differential pressure value W is greater than zero, the electrically controlled supercharging device is not started.

[0016] In step S2, when the actual value of the actual EGR rate is greater than the set value of the EGR rate in the current working condition, the speed of the turbocharger is controlled to be reduced; when the actual value of the actual EGR rate is less than the set value of the EGR rate in the current working condition, the speed of the turbocharger is controlled to be increased.

[0017] Flow meters are arranged in the exhaust pipe and the air intake pipe, and the actual EGR rate is calculated by using the flow method.

[0018] After the above method is used, when the ECU detects that the differential pressure between the two ends of the EGR valve is less than or equal to zero, it is detected whether the set value of the EGR rate in the current working condition is greater than zero, and when the above two conditions are met at the same time, the ECU controls the electrically controlled supercharging device to supercharge, and simultaneously monitors whether the actual value of the EGR rate is equal to the set value; if they are equal, the electrically controlled supercharging device maintains the current speed to supercharge. If they are not equal, there are two cases: when the actual value is lower than the set value, the speed is increased until they are equal. When the actual value is higher than the set value, the speed is reduced or directly stopped until they are equal. When the ECU detects that the differential pressure between the two ends of the EGR valve is greater than zero, the supercharging device does not need to work.

[0019] In summary, the application has the advantages of adjusting the intake pressure of the exhaust gas in real time to ensure the intake proportion of the exhaust gas and fresh air, thereby ensuring the EGR rate of the engine and the performance of the engine in real time. BRIEF DESCRIPTION OF DRAWINGS

[0020] The application will be further described below in combination with the drawings:

[0021] Figure 1 is a structural schematic diagram of one embodiment of the application. EMBODIMENT

[0022] As Figure 1 shown, the application provides a system capable of realizing and improving the EGR rate of an engine, Figure 1The system comprises an ECU of an engine, an exhaust pipe 1 and an air inlet pipe 2 connected to the engine, a storage unit for presetting the EGR rate under a preset working condition is arranged in the ECU of the engine. The exhaust pipe 1 and the air inlet pipe 2 are both connected to an EGR valve 3, the EGR valve 3 is electrically connected to the ECU of the engine, a mixed gas pipe 4 is further connected to the EGR valve 3, a pressure difference obtaining unit for obtaining the pressure difference between the pipe section of the exhaust pipe 1 in front of the EGR valve 3 and the pipe section of the air inlet pipe 2 behind the EGR valve 3 is arranged in the ECU, in the embodiment, a pressure detecting pipe 7 is connected to the pipe section of the exhaust pipe 1 in front of the EGR valve 3 and the pipe section of the air inlet pipe 2 behind the EGR valve 3 respectively, the ends of the two pressure detecting pipes 7 are connected to a pressure difference sensor 8, the pressure difference sensor 8 is electrically connected to the pressure difference obtaining unit of the ECU. Of course, the EGR valve 3 in front of the exhaust pipe 1 is provided with a first pressure sensor, the pipe section of the air inlet pipe 2 behind the EGR valve 3 is provided with a second pressure sensor, the pressure difference obtaining unit is used for reading the values of the first pressure sensor and the second pressure sensor to obtain the pressure difference, the specific structure of the two pressure sensors is not shown in the figure and will not be described in detail here.

[0023] With reference to Figure 1 As shown in the figure, the exhaust pipe 1 is further provided with an electrically controlled supercharging device for supercharging the exhaust gas in the exhaust pipe, the electrically controlled supercharging device comprises a turbocharger 5 connected in parallel to the exhaust pipe 1, the turbocharger 5 is further connected with a solenoid valve 6 for controlling whether the turbocharger 5 is started or not, the solenoid valve 6 is electrically connected to the ECU of the engine. Specifically, the exhaust pipe 1 is provided with a branch pipe 9 in parallel, a three-way valve 10 is arranged at the position where the exhaust pipe 1 is initially connected in parallel to the branch pipe 9, the three-way valve is electrically connected to the ECU and can control whether the exhaust gas flows through the exhaust pipe 1 or the branch pipe 9. Of course, the turbocharger 5 can be a turbocharger connected to the exhaust pipe 1, the specific structure of the turbocharger is the prior art and will not be described in detail here. Under normal working conditions, the exhaust gas is not supercharged, i.e. the exhaust gas directly enters the EGR valve 3 through the exhaust pipe, and the appropriate EGR rate can be obtained, but when the exhaust gas needs to be supercharged, the three-way valve is actuated, the exhaust gas enters the EGR valve after passing through the turbocharger on the branch pipe 9, so that the EGR rate is ensured.

[0024] With reference to Figure 1 Based on the above system, the application further provides a method for realizing and improving the EGR rate of the engine, the steps are as follows:

[0025] S1, under the current working condition, the pressure difference obtaining unit of the ECU of the engine obtains the pressure difference between the pipe section of the exhaust pipe in front of the EGR valve and the pipe section of the air inlet pipe behind the EGR valve in real time, and obtains the pressure difference value W; the obtaining unit of the ECU obtains the actual EGR rate;

[0026] S2. When the obtained pressure difference value W is less than or equal to zero, and the set value of the EGR rate under the current working condition in the storage unit is greater than zero, the electronically controlled supercharging device is started to boost the exhaust gas until the actual value of the EGR rate is equal to the set value of the EGR rate under the current working condition; when the obtained pressure difference value W is greater than zero, the electronically controlled supercharging device is not started.

[0027] In step S2, when the actual value of the actual EGR rate is greater than the set value of the EGR rate under the current working condition, the turbocharger is controlled to reduce the speed; when the actual value of the actual EGR rate is less than the set value of the EGR rate under the current working condition, the turbocharger is controlled to increase the speed.

[0028] It should be noted that the EGR rate on each engine is preset in the ECU according to different working conditions, and the EGR rate under actual conditions can be calculated in real time by setting a flow meter in the exhaust pipe 1 and the air inlet pipe 2. The above-mentioned detection process and structure are prior art and will not be described in detail here. The present invention can adjust whether to pressurize the exhaust gas in a timely manner according to the EGR rate under actual working conditions. It can not only ensure the EGR rate, but also does not need to pressurize the exhaust gas at all times, thereby greatly saving power resources and ensuring the EGR rate of the engine in real time. When the intake pressure of the engine EGR system is higher than the exhaust pressure, even if the EGR valve is open, the EGR rate cannot be obtained or an extremely low EGR rate cannot be obtained. This method and device can solve this problem.

[0029] The present invention is not limited to the above-mentioned embodiments. For those skilled in the art, equivalent changes based on the specific structure of the present invention and simple replacement of the method steps are all within the protection scope of the present invention.

Claims

1. A system capable of achieving and improving the EGR rate of an engine, comprising an ECU of the engine, an exhaust pipe and an air intake pipe connected to the engine, both the exhaust pipe and the air intake pipe being connected to an EGR valve, and a mixture pipe being further connected to the EGR valve, characterized in that, The ECU is provided with a differential pressure acquisition unit capable of acquiring the differential pressure between the exhaust pipe line before the EGR valve and the air inlet pipe line after the EGR valve, and the exhaust pipe is provided with an electrically controlled supercharging device capable of supercharging the exhaust gas in the exhaust pipe; the first pressure sensor is connected to the exhaust pipe line before the EGR valve, the second pressure sensor is connected to the air inlet pipe line after the EGR valve, and the differential pressure acquisition unit reads the values of the first pressure sensor and the second pressure sensor to obtain the differential pressure; the pressure detection pipes are connected to the exhaust pipe line before the EGR valve and the air inlet pipe line after the EGR valve respectively, the ends of the two pressure detection pipes are connected to the differential pressure sensor, and the differential pressure sensor is electrically connected to the differential pressure acquisition unit of the ECU; the ECU of the engine is provided with a storage unit pre-stored with the EGR rate value under the preset working condition; the exhaust pipe is provided with a branch pipe, and the three-way valve is arranged at the initial parallel connection position of the exhaust pipe and the branch pipe, and the three-way valve is electrically connected to the ECU.

2. The system of claim 1, wherein: The electrically controlled supercharging device comprises a turbocharger connected in parallel to the exhaust pipe, and the turbocharger is further connected with an electromagnetic valve for controlling whether the turbocharger is started or not, and the electromagnetic valve is electrically connected to the ECU of the engine.

3. The system of claim 1, wherein: The turbocharger is a turbo supercharger connected to the exhaust pipe.

4. A method of enabling and increasing the EGR rate of an engine, characterized by: The system capable of achieving and improving the EGR rate of the engine is adopted in any one of claims 1-3; S1, under the current working condition, the differential pressure acquisition unit of the ECU of the engine acquires the differential pressure between the exhaust pipe line before the EGR valve and the air inlet pipe line after the EGR valve in real time to obtain the differential pressure value W; the acquisition unit of the ECU acquires the actual EGR rate; S2, when the acquired differential pressure value W is less than or equal to zero, and the set value of the EGR rate under the current working condition in the storage unit is greater than zero, the electrically controlled supercharging device is started to supercharge the exhaust gas until the actual value of the actual EGR rate is equal to the set value of the EGR rate under the current working condition; when the acquired differential pressure value W is greater than zero, the electrically controlled supercharging device is not started.

5. The method of claim 4, wherein: In step S2, when the actual value of the actual EGR rate is greater than the set value of the EGR rate under the current working condition, the turbocharger is controlled to reduce the speed; when the actual value of the actual EGR rate is less than the set value of the EGR rate under the current working condition, the turbocharger is controlled to increase the speed.

6. The method for achieving and improving the engine EGR rate according to claim 4, characterized in that: Flow meters are arranged in the exhaust pipe and the air inlet pipe, and the flow method is adopted to calculate the actual EGR rate.

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