Exhaust gas recirculation system and one-way valve high-pressure protection method thereof

Abstract

The invention provides an exhaust gas recirculation system and a one-way valve high-pressure protection method thereof, and relates to the field of exhaust gas recirculation systems, according to the scheme, the exhaust gas recirculation system comprises an air inlet branch pipe, a control valve and a one-way valve are sequentially arranged on the air inlet branch pipe in the flowing direction of air in the air inlet branch pipe, and the exhaust gas recirculation system further comprises an air inlet valve, the air inlet valve is arranged on an air inlet pipe of the engine; the exhaust valve is arranged on an engine exhaust pipe, the first pressure sensor is arranged at the exhaust end of an air inlet branch pipe, and the first pressure sensor is used for detecting the exhaust pressure # imgabs0 #; the control valve, the air inlet valve, the exhaust valve and the first pressure sensor are all electrically connected with a controller. The one-way valve of the exhaust gas recirculation system can be prevented from high-pressure damage under the engine braking working condition.

Description

Technical Field

[0001] The invention relates to the field of exhaust gas recirculation systems, and in particular to an exhaust gas recirculation system and a one-way valve high-pressure protection method thereof. Background Art

[0002] The exhaust gas recirculation system (EGR for short) includes a control valve, a one-way valve, a valve opening sensor and a control unit. The exhaust gas recirculation system usually starts working after the engine is preheated. It is designed to reduce nitrogen oxide emissions and improve fuel efficiency under conditions of low engine load, moderate speed and suitable temperature. The EGR exhaust gas recirculation system is connected to the exhaust manifold and the intake manifold through a branch pipe to reintroduce part of the exhaust gas discharged by the engine into the intake manifold. On the one hand, the exhaust gas can absorb a large amount of heat, thereby reducing the combustion temperature in the cylinder. At the same time, the addition of exhaust gas also dilutes the oxygen concentration in the mixture, effectively reducing nitrogen oxide emissions and improving fuel efficiency.

[0003] In the prior art, commercial vehicles generally use engine exhaust braking to assist vehicle braking. The working principle of exhaust braking is to convert the engine into an air compressor to slow down the vehicle speed by compressing air. When the exhaust brake is activated, the fuel injector stops spraying fuel, but the engine continues to work, inhaling fresh air. The exhaust valve closes to block the exhaust pipe, so that the pressure in the exhaust pipe reaches 4 to 6 atmospheres. This braking method not only reduces the dependence on brake fluid, but also can provide stronger braking force, making the vehicle more stable.

[0004] When engine exhaust braking (engine braking for short) is used, the engine exhaust temperature will be at high pressure for a long time, which will increase the gas pressure in the exhaust gas recirculation system branch pipe. The one-way valve in the exhaust gas recirculation system will be in a high-pressure state for a long time and it is very easy to be damaged by high pressure, causing fresh air sucked in by the engine intake pipe to enter the EGR branch pipe, reducing the engine intake volume and affecting the engine's fuel economy. Summary of the invention

[0005] In order to solve the technical problem in the above-mentioned prior art that the sealing rubber in the one-way valve of the exhaust gas recirculation system is prone to high-pressure melting under the engine exhaust braking condition, the present invention provides an exhaust gas recirculation system and a one-way valve high-pressure protection method thereof, which can prevent the one-way valve of the exhaust gas recirculation system from being damaged by high pressure under the engine braking condition.

[0006] The technical solution adopted by the present invention to solve the above technical problems is: an exhaust gas recirculation system, including an intake branch pipe, along the gas flow direction in the intake branch pipe, a control valve and a one-way valve are arranged on the intake branch pipe in sequence, and also includes an intake valve, the intake valve is arranged on the engine intake pipe; an exhaust valve, the exhaust valve is arranged on the engine exhaust pipe, and a pressure sensor is arranged at the exhaust end of the intake branch pipe, and the pressure sensor is used to detect the exhaust pressure ; The control valve, the intake valve, the exhaust valve and the pressure sensor are all electrically connected to the controller.

[0007] The present invention can provide corresponding information to the system by detecting the exhaust end pressure of the intake branch pipe in real time, thereby avoiding high pressure damage to the one-way valve caused by excessive pressure and extending the service life of the exhaust gas recirculation system.

[0008] Furthermore, a cooler is provided between the control valve and the one-way valve.

[0009] The present invention prevents the gas temperature in the intake branch pipe from being too high by arranging a cooler.

[0010] Furthermore, the control valve is a butterfly valve, an opening sensor is provided on the control valve, and the opening sensor is electrically connected to the controller.

[0011] The present invention can enable the controller to form a closed loop for the control valve opening control by arranging the opening sensor, and can realize the system self-check whether the control valve is stuck.

[0012] Furthermore, the air intake valve is a throttle valve.

[0013] Furthermore, the exhaust valve is a butterfly valve.

[0014] In a second aspect, the present invention provides a high-pressure protection method for a one-way valve of an exhaust gas recirculation system, which adopts the above-mentioned exhaust gas recirculation system and comprises the following steps under engine braking conditions: When the exhaust pressure on the intake manifold When the pressure is greater than the set pressure threshold, the intake valve reduces the intake volume until the exhaust pressure is less than the set pressure threshold, and the intake valve then adjusts the intake volume to the initial intake volume.

[0015] The present invention monitors the exhaust pressure , to ensure that the exhaust pressure If it is too large, reduce the exhaust pressure by reducing the intake volume in time. , to avoid excessive exhaust pressure in the exhaust gas recirculation system, which may cause high-pressure damage to the one-way valve.

[0016] Furthermore, the pressure thresholds are set to P1, P2 and P3, and P1<P2<P3, P1, P2 and P3 divide the pressure value into four pressure levels: normal, small, medium and large, and the opening of the intake valve is also correspondingly set to four levels: normal, small, medium and large.

[0017] The present invention sets four levels corresponding to the pressure value and the exhaust valve opening, thereby achieving accurate adjustment of the intake volume according to the exhaust pressure, avoiding a "one-size-fits-all" mode that affects the engine braking effect.

[0018] Furthermore, after the control valve receives the adjustment opening signal, when the actual opening feedback from the opening sensor deviates from the opening target value and does not change within a set time threshold, the exhaust valve increases the exhaust volume.

[0019] The present invention sends an opening adjustment signal to the control valve through the system self-check function, detects whether the control valve can reach the opening target value within a set time threshold, and determines whether the control valve is stuck, thereby avoiding damage to the one-way valve caused by increased intake volume and increased pressure after a control valve failure.

[0020] Furthermore, when the actual opening feedback from the opening sensor deviates from the opening target value and does not change within the set time threshold, the EGR control valve fault light on the cab monitoring screen lights up.

[0021] The present invention controls the EGR control valve fault lamp to timely remind the driver to check the control valve of the exhaust gas recirculation system.

[0022] Furthermore, after parking, the vehicle is powered off and restarted, and a self-test signal is sent to the control valve. When the actual opening feedback from the opening sensor deviates from the opening target value and does not change within the set time threshold, the EGR control valve fault light on the cab monitoring screen lights up again, indicating that the control valve needs to be repaired. After replacing the control valve, the vehicle is powered off and restarted, and a self-test signal is sent to the control valve. When the actual opening feedback from the opening sensor deviates from the opening target value and does not change within the set time threshold, the EGR control valve fault light on the cab monitoring screen lights up again, indicating that the new control valve should be checked. Otherwise, the EGR control valve fault light will not light up and the exhaust gas recirculation system can work normally.

[0023] The present invention ensures that the fault judgment is correct and the new control valve can work normally by performing a system self-check before and after the control valve is replaced, thereby ensuring the effectiveness of the maintenance.

[0024] It can be seen from the above technical solutions that the present invention has the following advantages: The present invention provides an exhaust gas recirculation system and a one-way valve high-pressure protection method thereof. By real-time detection of the exhaust end pressure of the intake branch pipe, corresponding information can be provided to the system to avoid high-pressure damage to the one-way valve caused by excessive pressure, thereby extending the service life of the exhaust gas recirculation system; by setting a cooler, the gas temperature in the intake branch pipe can be prevented from being too high; by setting an opening sensor, the controller can form a closed loop for the control valve opening control, and the system can self-check whether the control valve is stuck; by monitoring the exhaust pressure , to ensure that the exhaust pressure If it is too large, reduce the exhaust pressure by reducing the intake volume in time. , avoid excessive exhaust pressure in the exhaust gas recirculation system, which may cause high-pressure damage to the one-way valve; by setting the pressure value and the exhaust valve opening to four levels, the intake volume can be accurately adjusted according to the exhaust pressure, avoiding the "one-size-fits-all" mode and affecting the engine braking effect; through the system self-check function, an opening adjustment signal is sent to the control valve, and the control valve is detected to see whether it can reach the opening target value within the set time threshold, and whether the control valve is stuck, so as to avoid damage to the one-way valve caused by increased intake volume and increased pressure after a control valve failure; by controlling the EGR control valve fault light, the driver is promptly reminded to check the control valve of the exhaust gas recirculation system; by performing a system self-check before and after replacing the control valve, it is ensured that the fault judgment is correct and the new control valve can work normally, thereby ensuring the effectiveness of the maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solution of the present invention, the accompanying drawings required for use in the description will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0026] Figure 1 It is a schematic diagram of the structural principle of a specific implementation mode 1 of the present invention.

[0027] Figure 2 This is a flow chart of regulating the exhaust pressure in the second specific implementation mode of the present invention.

[0028] Figure 3 This is a flow chart for monitoring whether a control valve is stuck in the second specific implementation mode of the present invention.

[0029] In the figure, 1. engine; 2. control valve; 3. cooler; 4. check valve; 5. pressure sensor; 6. intake valve; 7. exhaust valve; 8. intake pipe; 9. exhaust pipe; 10. intake branch pipe. DETAILED DESCRIPTION

[0030] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in this specific embodiment. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of them. Based on the embodiments in this patent, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this patent.

[0031] like Figure 1 As shown, this specific embodiment provides an exhaust gas recirculation system, including an intake branch pipe 10, an intake valve 6, an exhaust valve 7, a pressure sensor 5, a control valve 2 and a one-way valve 4; along the gas flow direction in the intake branch pipe 10, the control valve 2 and the one-way valve 4 are sequentially arranged on the intake branch pipe 10, the intake valve 6 is arranged on the intake pipe 8 of the engine 1, the intake valve 6 is used to control and adjust the intake amount, the exhaust valve 7 is arranged on the exhaust pipe 9 of the engine 1, and is used to control and adjust the exhaust amount; the pressure sensor is arranged at the exhaust end of the intake branch pipe 10, and the pressure sensor is used to detect the exhaust pressure; the control valve 2, the intake valve 6, the exhaust valve 7 and the pressure sensor are all electrically connected to the controller, and in this specific embodiment, the controller refers to the vehicle controller.

[0032] like Figure 1 As shown, in order to reduce the temperature of the exhaust gas entering the engine 1, in this specific embodiment, a cooler 3 is arranged between the control valve 2 and the one-way valve 4; the control valve 2 adopts a butterfly valve, and an opening sensor is arranged on the control valve 2, and the opening sensor is electrically connected to the controller. Through the opening sensor, it can be known whether the control valve 2 obtains the opening target value; the intake valve 6 adopts a throttle valve, and the exhaust valve 7 adopts a butterfly valve. Specific implementation method 2 like Figure 2 As shown, this specific embodiment provides a high-pressure protection method for a one-way valve of an exhaust gas recirculation system, using the exhaust gas recirculation system of specific embodiment 1, and under the braking condition of the engine 1, the exhaust valve 7 is closed and no exhaust is performed, comprising the following steps: When the controller determines the exhaust pressure on the intake branch pipe 10 When the pressure is greater than the set pressure threshold, the intake valve 6 is adjusted to reduce the intake volume until the exhaust pressure When the pressure is less than the set pressure threshold, the intake valve 6 adjusts the intake volume to the initial intake volume.

[0034] The working principle of this specific embodiment is: when the intake volume of the engine 1 is reduced, in the braking mode, the total amount of gas transferred to the exhaust pipe 9 is reduced, which also reduces the intake pressure of the exhaust gas recirculation system, thereby effectively reducing the exhaust pressure. , to prevent high pressure from damaging the one-way valve 4; this specific implementation method monitors the exhaust pressure , to ensure that the exhaust pressure If it is too large, reduce the exhaust pressure by reducing the intake volume in time. , avoiding exhaust pressure in the exhaust gas recirculation system Too large, causing high pressure damage to the one-way valve 4.

[0035] like Figure 2 As shown, in order to accurately adjust the intake volume and avoid ensuring the exhaust pressure When the pressure is lower than the set threshold, the intake volume of the engine 1 is greatly reduced, affecting the braking of the engine 1. In this specific embodiment, the pressure threshold is set to P1, P2 and P3, and P1<P2<P3. P1, P2 and P3 divide the pressure value into four pressure levels: normal, small, medium and large. P3 is determined by the maximum pressure resistance value of the rubber sealing ring. The opening of the intake valve 6 is also set to four levels: normal, small, medium and large. When the exhaust pressure After decreasing to within P1, the intake valve restores the original intake volume; in this specific embodiment, P1 is set to 330 kPa, P2 is set to 340 kPa, P3 is set to 350 kPa, and the opening of the intake valve 6 is set to 0%, 5%, 10% and 15% respectively. The larger the opening, the smaller the intake volume, that is, when Less than 330kPa, the intake valve 6 is fully open at 0%, and the intake volume is maximum at this time. ≤340kPa, the opening of the intake valve 6 is 5%, which reduces the intake volume to a small extent and reduces the pressure. ≤350kPa, the opening of the intake valve 6 is 10%, the intake volume is moderately reduced, and when 350kPa≤ When the engine 1 is running, the opening of the intake valve 6 is 15%, and the intake volume is reduced to the maximum extent while ensuring the braking effect of the engine 1; after running for a period of time, when it is reduced to within P1, the opening of the intake valve 6 is reduced to full open, and the intake volume is adjusted back to the initial intake volume; after this setting, the exhaust pressure can be adjusted according to the exhaust pressure. Accurately adjust the intake volume to avoid the "one-size-fits-all" adjustment mode that affects the braking effect of the engine 1.

[0036] like Figure 3As shown, in order to timely detect the jam of the control valve 2 and protect the one-way valve 4 when the control valve 2 is jammed, a "self-check" function is added in this specific embodiment. The controller periodically sends an adjustment signal to the control valve 2 of the exhaust gas recirculation system. The given opening target value is different from the existing opening of the control valve 2. After receiving the adjustment signal, the control valve 2 performs the adjustment action. When the actual opening feedback from the opening sensor deviates from the opening target value and does not change within the set time threshold, this indicates that the control valve 2 is jammed, the sealing ring of the control valve 2 is melted, and the sealing cannot be achieved. The control valve 2 is Leakage, there is a tendency of pressure increase at the one-way valve 4. To protect the one-way valve 4, the exhaust valve 7 is opened to increase the exhaust volume, and the intake volume through the control valve 2 is reduced to avoid the pressure increase at the one-way valve 4; the actual opening feedback from the opening sensor is a voltage signal, and the voltage signal and the opening of the control valve 2 are calibrated in advance. In this specific implementation, the time threshold is set to 5s; in order to promptly improve the driver's control valve 2 stuck, when the actual opening feedback from the opening sensor deviates from the opening target value and does not change within the set time threshold, it is judged that the control valve 2 is stuck, and the EGR control valve 2 fault light on the cab monitoring screen lights up.

[0037] To avoid misjudgment of control valve 2 failure and increase inspection work, after the driver stops the car for inspection and restarts after power off, the system control performs "self-check" again. The controller periodically sends a signal to adjust the opening of control valve 2 of the exhaust gas recirculation system. The opening target value given is different from the existing opening of the adjustment valve. Control valve 2 performs the adjustment action after receiving the actual opening adjustment. When the actual opening feedback from the opening sensor deviates from the opening target value and does not change within the set time threshold, this indicates that control valve 2 is indeed stuck, and the EGR control valve 2 fault light on the cab monitoring screen lights up, and needs to be replaced and repaired.

[0038] To ensure that the new control valve 2 can work normally after being replaced and to ensure the effectiveness of maintenance, in this specific embodiment, after the control valve 2 is replaced, the vehicle is powered off and restarted, and the controller sends a self-test signal to the control valve 2, that is, the controller sends a signal to the control valve 2 to adjust the opening. When the actual opening feedback from the opening sensor deviates from the opening target value and does not change within the set time threshold, it indicates that the new control valve 2 has a fault, and the EGR control valve 2 fault light on the cab monitoring screen lights up again, prompting the new control valve 2 to be checked. Otherwise, the EGR control valve 2 fault light will not light up, and the exhaust gas recirculation system can work normally.

[0039] This specific implementation method takes two approaches to avoid high pressure damage to the one-way valve 4. On the one hand, the exhaust pressure is regulated. , to avoid excessive intake pressure of the exhaust gas recirculation system in the engine 1 braking mode, which will cause the exhaust pressure On the other hand, monitor whether the control valve 2 is stuck or leaking to avoid the exhaust pressure of the check valve 4 caused by the leakage of the control valve 2. Through the cooperation of these two aspects, comprehensive protection of the one-way valve 4 is achieved to avoid high-pressure damage.

[0040] From the above specific implementations, it can be seen that the present invention has the following beneficial effects: 1. By real-time detection of the exhaust end pressure of the intake manifold 10, the system can be provided with corresponding information to avoid high pressure damage to the one-way valve 4 caused by excessive pressure, thereby extending the service life of the exhaust gas recirculation system; 2. Prevent the gas temperature in the intake branch pipe 10 from being too high by providing a cooler 3; 3. By setting the opening sensor, the controller can form a closed loop for the opening control of the control valve 2, and the system can self-check whether the control valve 2 is stuck; 4. By monitoring the exhaust pressure, ensure that when the exhaust pressure is too high, reduce the exhaust pressure by reducing the intake volume in time to avoid excessive exhaust pressure of the exhaust gas recirculation system, causing high pressure damage to the check valve 4; 5. By setting the pressure value and the opening of the exhaust valve 7 to four levels, the intake volume can be accurately adjusted according to the exhaust pressure, avoiding the "one-size-fits-all" mode that affects the braking effect of the engine 1; 6. Send an opening adjustment signal to the control valve 2 through the system self-check function, and detect whether the control valve 2 can reach the opening target value within the set time threshold, and judge whether the control valve 2 is stuck, so as to avoid damage to the check valve 4 caused by increased intake volume and pressure after the control valve 2 fails; 7. By controlling the EGR control valve 2 fault light, the driver is reminded to check the control valve 2 of the exhaust gas recirculation system in time; 8. By performing a self-check on the system before and after replacing the control valve 2, it is ensured that the fault diagnosis is correct and the new control valve 2 can work normally, thus ensuring the effectiveness of the maintenance.

[0041] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An exhaust gas recirculation system, comprising an intake branch pipe (10), wherein a control valve (2) and a non-return valve (4) are sequentially arranged on the intake branch pipe (10) along the gas flow direction in the intake branch pipe (10), characterized in that: Also includes, An intake valve (6), the intake valve (6) being arranged on an intake pipe of the engine; An exhaust valve (7), wherein the exhaust valve (7) is arranged on an exhaust pipe of the engine, A pressure sensor (5), the pressure sensor (5) being arranged at the exhaust end of the intake branch pipe (10), the pressure sensor (5) being used to detect the exhaust pressure; The control valve (2), the intake valve (6), the exhaust valve (7) and the pressure sensor (5) are all electrically connected to a controller.

2. The exhaust gas recirculation system according to claim 1, characterized in that A cooler (3) is provided between the control valve (2) and the one-way valve (4).

3. The exhaust gas recirculation system according to claim 2, characterized in that: The control valve (2) is a butterfly valve, and an opening sensor is provided on the control valve (2), and the opening sensor is electrically connected to the controller.

4. The exhaust gas recirculation system according to claim 3, characterized in that: The air intake valve (6) is a throttle valve.

5. The exhaust gas recirculation system according to claim 4, characterized in that: The exhaust valve (7) is a butterfly valve.

6. A high pressure protection method for a one-way valve of an exhaust gas recirculation system, characterized in that: The exhaust gas recirculation system according to any one of claims 3 to 5, and under engine braking conditions, comprises the following steps: When the exhaust pressure on the intake manifold When the pressure is greater than the set pressure threshold, the intake valve reduces the intake volume until the exhaust pressure is less than the set pressure threshold, and the intake valve then adjusts the intake volume to the initial intake volume.

7. The high pressure protection method for the one-way valve of the exhaust gas recirculation system according to claim 6, characterized in that: The pressure thresholds are set to P1, P2 and P3, and P1<P2<P3. P1, P2 and P3 divide the pressure value into four pressure levels: normal, small, medium and large. The opening of the intake valve is also correspondingly set to four levels: normal, small, medium and large.

8. The high pressure protection method for the one-way valve of the exhaust gas recirculation system as claimed in claim 6, characterized in that: After the control valve receives the adjustment opening signal, when the actual opening feedback from the opening sensor deviates from the opening target value and does not change within the set time threshold, the exhaust valve increases the exhaust volume.

9. The high pressure protection method for the one-way valve of the exhaust gas recirculation system as claimed in claim 8, characterized in that: When the actual opening feedback from the opening sensor deviates from the opening target value and does not change within the set time threshold, the EGR control valve fault light on the cab monitoring screen lights up.

10. The high pressure protection method for the one-way valve of the exhaust gas recirculation system according to claim 9, characterized in that: After parking, the vehicle is powered off and restarted, and a self-test signal is sent to the control valve. When the actual opening feedback from the opening sensor deviates from the opening target value and does not change within the set time threshold, the EGR control valve fault light on the cab monitoring screen lights up again, indicating that the control valve needs to be repaired. After replacing the control valve, the vehicle is powered off and restarted, and a self-test signal is sent to the control valve. When the actual opening feedback from the opening sensor deviates from the opening target value and does not change within the set time threshold, the EGR control valve fault light on the cab monitoring screen lights up again, indicating that the new control valve should be checked. Otherwise, the EGR control valve fault light will not light up and the exhaust gas recirculation system can work normally.

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