A method for improving the low temperature before DOC during vehicle parking regeneration

Abstract

The present invention discloses a method for improving the low temperature before the DOC during vehicle parking regeneration, comprising: S10: pressing the regeneration request switch, after time ti, the ECU obtains a first temperature value T0 upstream of the DOC measured by a temperature sensor, and an initial TVA opening value A0; S20: a comparison unit of the ECU determines whether the first temperature value T0 is less than a target temperature T; S30: in response to the determination result that T0 is less than T, a correction unit calculates a TVA target opening value An; S40: after adjusting the TVA real-time opening value to be equal to the TVA target opening value An, the ECU obtains a second temperature value upstream of the DOC and forms a comparison value T1; S50: the comparison unit determines whether the comparison value T1 is less than the target temperature T; S60: in response to the determination result that T1 is less than T, the step of correcting the TVA target opening value An is repeated until T1 is not less than T. The present invention has the characteristics of being able to perform real-time correction of the TVA opening based on the DOC upstream temperature, thereby ensuring that the DOC upstream temperature reaches the appropriate regeneration temperature, and the temperature rise is stable, thus saving regeneration time.

Description

Technical Field

[0001] The present invention relates to the field of parking regeneration, and in particular to a method for improving the low temperature before DOC during parking regeneration of a vehicle. Background Art

[0002] Parking regeneration means that when the adsorbed particulates reach a certain amount, the DPF tail end burner ignites and burns, burning all the particles adsorbed on the metal fiber felt, turning them into harmless carbon dioxide and discharging them into the air. The parking regeneration process requires the addition of an electronic control system and a DOC. During parking regeneration, due to unsatisfactory thermal management, the temperature before the DOC is low, which affects the HC oxidation rate, resulting in a low HC oxidation rate, an unsatisfactory DOC regeneration temperature, a long regeneration time and a large HC leakage. The existing technology adjusts the opening of the intake throttle valve TVA by the intake pressure to increase the exhaust temperature. For example, the application number is 201610402900.8, and the invention name is A Heavy-Duty Vehicle DPF Regeneration Control System, which discloses controlling the opening of the intake throttle valve 3 and the EGR valve 4 (generally, the EGR valve 4 is completely closed, that is, zero exhaust gas enters the engine intake pipe to prevent exhaust gas temperature loss; the intake throttle valve 3 is closed by more than 50%, that is, a part of the fresh air intake is closed to achieve a heat preservation effect), so that the DOC 8. The upstream temperature is controlled within 350℃-400℃. This correction cannot guarantee that it can adapt to all vehicles or other ambient temperatures. Due to the consistency deviation of the whole vehicle, the temperature before DOC will not meet the minimum regeneration requirement (generally around 280℃), and thus regeneration will be impossible. At the same time, when the opening of the intake throttle valve is too large at one time, the temperature will fluctuate greatly, and it is impossible to determine whether the temperature before DOC meets the minimum regeneration requirement. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for improving the low temperature before DOC during vehicle parking regeneration, which can make real-time corrections to the TVA opening based on the DOC upstream temperature to ensure that the DOC upstream temperature reaches the appropriate regeneration temperature and the temperature rises smoothly, saving regeneration time.

[0004] To solve the above technical problems, a method for improving the low temperature before the DOC during vehicle parking regeneration is provided, wherein the vehicle includes an engine, a TVA connected to the engine intake pipe, a DOC and a DPF connected to the engine exhaust pipe in sequence along the exhaust direction, the engine is connected to an ECU, the DOC is equipped with a temperature sensor electrically connected to the ECU, and the ECU is also electrically connected to a timer and a regeneration request switch. The structural characteristics of the method are: a correction unit and a comparison unit are provided in the ECU, and a control unit is electrically connected to the correction unit and the comparison unit respectively, the comparison unit is preset with a target temperature T, and the correction unit is preset with a correction opening value ΔA and a correction time interval ΔT. The method includes:

[0005] S10: Press the regeneration request switch. After time ti, the ECU obtains a first temperature value T0 upstream of the DOC and an initial opening value A0 of the TVA measured by the temperature sensor.

[0006] S20: The comparison unit of the ECU determines whether the first temperature value T0 is less than the target temperature T;

[0007] S30: In response to a determination that the first temperature value T0 is less than the target temperature T, the correction unit corrects the TVA target opening value An according to the corrected opening value ΔA, the corrected time interval ΔT, and the initial opening value A0; wherein An=A0-ΔA*(nΔT), where n is an integer greater than or equal to 1;

[0008] S40: After adjusting the TVA real-time opening value to be equal to the TVA target opening value An, the ECU obtains a second temperature value upstream of the DOC measured by the temperature sensor and forms a comparison value T1; wherein the TVA real-time opening value is greater than or equal to the target opening value An after each correction;

[0009] S50: The comparison unit of the ECU determines whether the comparison value T1 is less than the target temperature T;

[0010] S60 : In response to the judgment result that the comparison value T1 is less than the target temperature T, the step of correcting the TVA target opening value An is repeated until the comparison value T1 is not less than the target temperature T.

[0011] Furthermore, the comparison value T1 is set to be equal to a second temperature value upstream of the DOC measured by the temperature sensor.

[0012] Furthermore, the comparison value T1 is set to be equal to the difference between the second temperature value upstream of the DOC measured by the temperature sensor and the hysteresis temperature preset in the ECU.

[0013] Furthermore, the hysteresis temperature is 10°C.

[0014] Furthermore, the TVA initial opening value A0 ranges from 20% to 30%.

[0015] Furthermore, the corrected opening value ΔA is a fixed opening value corrected within a unit time.

[0016] Furthermore, the corrected opening value ΔA is 0.01% / s.

[0017] Furthermore, the target temperature T is in the range of 300°C-350°C.

[0018] Furthermore, the correction time interval ΔT has a value range of 10s-30s.

[0019] Furthermore, the value range of ti is 100s-300s.

[0020] After adopting the above method, when it is determined that the first temperature value T0 is less than the target temperature T, the TVA opening is corrected in real time based on the DOC upstream temperature, that is, the correction is made gradually over time. During the TVA opening correction process, the DOC upstream temperature will not fluctuate significantly, and the DOC upstream temperature will eventually reach a suitable regeneration temperature (generally >300°C), allowing the entire vehicle to regenerate smoothly. By correcting the TVA opening value in real time, the DOC upstream temperature and DPF regeneration temperature are increased, regeneration efficiency is accelerated, and regeneration time is saved. By setting a hysteresis temperature, the DOC upstream temperature is prevented from fluctuating around the set value, resulting in repeated corrections to the TVA opening and failure to stabilize the TVA opening value. The temperature sensor detects the DOC upstream temperature value once at the end of the unit time △T. The DOC upstream temperature at the end of the unit time △T tends to be stable. At this time, the measurement error is small and the measurement is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a flow chart of a method for improving the low temperature before the DOC during parking regeneration of a vehicle provided by an embodiment of the present invention. Implementation Method

[0022] Reference Figure 1 The method for improving the low temperature before the DOC during vehicle parking regeneration involves a vehicle including an engine, a TVA (i.e., an intake throttle valve) connected to the engine's intake pipe, a DOC (i.e., a diesel oxidation catalyst unit) and a DPF (i.e., a diesel particulate filter) connected sequentially to the engine's exhaust pipe along the exhaust direction. The engine is connected to an ECU, and the DOC is equipped with a temperature sensor electrically connected to the ECU. Specifically, the temperature sensor can be installed at the upstream end of the DOC or in the exhaust pipe upstream of the DOC. The ECU is also electrically connected to a timer and a regeneration request switch, wherein the regeneration request switch can be installed in the cab or on an operating table in a test laboratory. The ECU is provided with a correction unit and a comparison unit, as well as a control unit electrically connected to the correction unit and the comparison unit. The comparison unit of the ECU is preset with a target temperature T, and the correction unit is preset with a correction opening value ΔA and a correction time interval ΔT. The method includes:

[0023] S10: Press the regeneration request switch. After time ti, the ECU obtains the first temperature value T0 upstream of the DOC measured by the temperature sensor and the initial opening value A0 of the TVA;

[0024] S20: The comparison unit of the ECU determines whether the first temperature value T0 is less than the target temperature T;

[0025] S30: In response to the determination that the first temperature value T0 is less than the target temperature T, the correction unit corrects the TVA target opening value An based on the corrected opening value ΔA, the corrected time interval ΔT, and the initial opening value A0; wherein An=A0-ΔA*(nΔT), where n is an integer greater than or equal to 1 and is initially counted from 1;

[0026] S40: After adjusting the TVA real-time opening value to be equal to the TVA target opening value An, the ECU obtains a second temperature value upstream of the DOC measured by the temperature sensor and forms a comparison value T1; wherein the TVA real-time opening value is greater than or equal to the target opening value An after each correction;

[0027] S50: The comparison unit of the ECU determines whether the comparison value T1 is less than the target temperature T;

[0028] S60 : In response to the judgment result that the comparison value T1 is less than the target temperature T, the step of correcting the TVA target opening value An is repeated until the comparison value T1 is not less than the target temperature T.

[0029] For example, if the TVA opening needs to be adjusted from 40% to 20%, the prior art uses a one-step method to achieve this. However, when the TVA opening is adjusted directly to the desired value, the DOC upstream temperature and the DPF temperature fluctuate significantly. During regeneration, after the DOC upstream temperature stabilizes, it may deviate (larger or smaller) from the temperature measured when the adjustment is completed, resulting in unsatisfactory regeneration. The present invention, however, uses a multi-step method to adjust the TVA opening in real time. Once the TVA opening is adjusted to a certain value, the DOC temperature is acquired and compared when the DOC temperature stabilizes. This makes the acquired DOC temperature more accurate, ensuring optimal results. Ultimately, the DOC upstream temperature (pre-DOC temperature) reaches a suitable regeneration temperature, allowing the vehicle to regenerate smoothly. Especially when dealing with a variety of different vehicle models, the required opening values ​​are different. For this reason, in the prior art, it is necessary to preset multiple opening values ​​that are about to be reached, that is, the engine of each vehicle model needs to be preset once. Through the design of the present invention, a multi-step method is used to perform gradual adjustments in real time, and the TVA can be corrected in real time based on the DOC upstream temperature. The DOC upstream temperature will not fluctuate greatly, and ultimately the DOC upstream temperature of different vehicle models will reach a suitable regeneration temperature.

[0030] Reference Figure 1There are two specific implementations of the comparison value T1. One is that the comparison value T1 is equal to the second temperature value upstream of the DOC measured by the temperature sensor. Preferably, the second comparison value T1 is the difference between the second temperature value upstream of the DOC measured by the temperature sensor and the hysteresis temperature preset in the ECU. At this time, judging whether the comparison value T1 is less than the target temperature T, that is, judging whether the difference between the second temperature value upstream of the DOC measured by the temperature sensor and the hysteresis temperature is less than the target temperature T, is also equivalent to judging whether the second temperature value upstream of the DOC measured by the temperature sensor is less than the sum of the target temperature T and the hysteresis temperature. The purpose of setting the hysteresis temperature is to prevent the DOC upstream temperature (second temperature value) from fluctuating around the target temperature T, resulting in repeated correction of the TVA opening and failure to stabilize the TVA opening value at a certain value. Specifically, when the second temperature value upstream of the DOC exceeds the sum of the target temperature T and the hysteresis temperature, the TVA opening stops correcting and stabilizes at the current opening value. If at this time the DOC upstream temperature drops slightly due to environmental reasons, the TVA opening can only be re-enabled for correction when it drops below the target temperature T. This is equivalent to giving the TVA opening adjustment command a buffer. Without this buffer, the TVA opening may be adjusted repeatedly, causing the DOC upstream temperature to fluctuate back and forth and become unstable. The hysteresis temperature is generally 10°C.

[0031] Reference Figure 1 The corrected opening value △A is the fixed opening value corrected per unit time, and the fixed opening value is a constant value. Preferably, the corrected opening value △A is 0.01% / s, that is, the TVA opening value is corrected by 0.01% per second, and the fixed opening value is 0.01%. It can be set according to different models to prevent the value from being too large, which causes the DOC upstream temperature to change too quickly, or too small, which causes the DOC upstream temperature to change slowly. The TVA opening is corrected in real time based on the DOC upstream temperature. During the TVA opening correction process, since it is a real-time correction, it is gradually adjusted over time. For example, it is adjusted 20 times within 20 seconds, that is, the TVA opening value is only adjusted by 0.01% each time. The DOC upstream temperature after each adjustment will not fluctuate greatly. At the end of 20 seconds, the second temperature value of the DOC upstream is close to stable. At this time, the comparison value T1 and the target temperature T are judged to determine whether to proceed to the next cycle. n is the number of cycles. After one or more cycles, the DOC upstream temperature is finally made to reach a suitable regeneration temperature, allowing the entire vehicle to regenerate smoothly. Among them, the value range of the target temperature T is 300℃-350℃, preferably, T is 300℃; the value range of △T is 10s-30s, preferably, △T is 20s; the value range of ti is 100s-300s, preferably, ti is 200s; the value range of the TVA initial opening value A0 is 20%-30%. Example 1

[0032] When the regeneration request switch is pressed, the engine enters parking regeneration. After a time ti (200s), the ECU obtains the first temperature value T0 upstream of the DOC measured by the temperature sensor as 265°C, and the TVA initial opening value A0 is 24.5%. At this time, the DPF regeneration temperature is 590°C. The detection and display of the DPF regeneration temperature are both existing technologies, that is, a DPF temperature sensor is set on the DPF, the DPF temperature sensor is electrically connected to the ECU, and the ECU program presets the target temperature T=300°C.The comparison unit of the ECU determines that the first temperature value T0 (265°C) upstream of the DOC measured by the temperature sensor is lower than the target temperature T (300°C), and activates the correction. In response to the judgment result that the first temperature value T0 (265°C) is lower than the target temperature T (300°C), the correction unit corrects the TVA target opening value An based on the correction opening value △A (0.01% / s), the correction time interval △T (20s), and the initial opening value A0 (24.5%); wherein n is an integer greater than or equal to 1, that is, the number of cycles, and the initial n is counted from 1. The first correction n=1, An=A1=A0-△A*( 1△T) = 24.5% - 0.01* (1*20) = 24.3%, that is, within 20s, the TVA opening is corrected by 0.01% for every 1s increase in time. During this period, the TVA opening value is the TVA real-time opening value. As time increases, the TVA real-time opening value gradually decreases. After 20s, the TVA real-time opening value is adjusted to be equal to the TVA target opening value An (that is, A1 = 24.3%). Then, the ECU obtains the second temperature value upstream of the DOC measured by the temperature sensor and forms a comparison value T1. At this time, the comparison unit of the ECU determines that the comparison value T1 is still less than the target temperature T (300℃), and then continues to adjust. Positive, repeat the steps of correcting the TVA target opening value An. When the second correction is performed, An=A2=A0-△A*(2△T)=24.5%-0.01*(2*20)=24.1%. Then, the ECU obtains the second temperature value upstream of the DOC measured by the temperature sensor and forms a comparison value T1. At this time, the comparison unit of the ECU determines that the comparison value T1 is still less than the target temperature T (300℃). Then, the correction is repeated for the third, fourth, fifth and other integer times. Finally, after about 200s, that is, after n=10 times △T, the second temperature value upstream of the DOC is 315℃. At this time, the comparison value T When 1 equals the second temperature upstream of the DOC measured by the temperature sensor, 315°C, the comparison value T1 exceeds the target temperature T (300°C). When the comparison value T1 equals the difference between the second temperature upstream of the DOC measured by the temperature sensor (315°C) and the hysteresis temperature (10°C) preset in the ECU, that is, when the comparison value T1 equals 305°C (315°C - 10°C), the comparison value T1 is still greater than the target temperature T (300°C). At this time, the TVA opening is no longer adjusted. The TVA target opening value An = A10 = A0 - ΔA * (10ΔT) = 24.5% - 0.01 * (10 * 20) = 22.5%. Through TVA opening correction, the DOC upstream temperature (i.e., the second temperature) ultimately stabilizes at around 315°C. The regeneration temperature can be increased from 590°C before correction to 615°C (close to the ideal DPF regeneration temperature), accelerating regeneration efficiency and ultimately shortening the regeneration time to approximately 1800 seconds. The engine does not enable this logic verification regeneration time is about 2250s, as shown below:.

[0033] parameter unit Before correction After correction TVA opening value % 24.5 22.5 DOC upstream temperature ℃ 265 305 DPF regeneration temperature ℃ 590 615 Regeneration time s 2250 1800

[0034] Therefore, it can be concluded that real-time correction can improve the DOC upstream temperature and DPF regeneration temperature, speed up the regeneration efficiency and save regeneration time.

[0035] The present invention is not limited to the above embodiments. For those skilled in the art, equivalent changes based on the specific structure of the present invention and simple replacement of method steps are all within the protection scope of the present invention.

[0036] The present invention discloses a method for improving the low temperature before the DOC during vehicle parking regeneration, comprising: S10: pressing the regeneration request switch, after time ti, the ECU obtains a first temperature value T0 upstream of the DOC measured by a temperature sensor, and an initial TVA opening value A0; S20: a comparison unit of the ECU determines whether the first temperature value T0 is less than a target temperature T; S30: in response to the determination result that T0 is less than T, a correction unit calculates a TVA target opening value An; S40: after adjusting the TVA real-time opening value to be equal to the TVA target opening value An, the ECU obtains a second temperature value upstream of the DOC and forms a comparison value T1; S50: the comparison unit determines whether the comparison value T1 is less than the target temperature T; S60: in response to the determination result that T1 is less than T, the step of correcting the TVA target opening value An is repeated until T1 is not less than T. The present invention has the characteristics of being able to perform real-time correction of the TVA opening based on the DOC upstream temperature, thereby ensuring that the DOC upstream temperature reaches the appropriate regeneration temperature, and the temperature rise is stable, thus saving regeneration time.

Claims

1. A method for improving the low temperature before the DOC during vehicle parking regeneration, wherein the vehicle includes an engine, a TVA connected to the engine intake pipe, a DOC and a DPF connected to the engine exhaust pipe in sequence along the exhaust direction, the engine is connected to an ECU, the DOC is equipped with a temperature sensor electrically connected to the ECU, and the ECU is also electrically connected to a timer and a regeneration request switch, wherein: The ECU is provided with a correction unit and a comparison unit, and a control unit electrically connected to the correction unit and the comparison unit respectively. The comparison unit is preset with a target temperature T, and the correction unit is preset with a correction opening value ΔA and a correction time interval ΔT. The method includes: S10: Press the regeneration request switch. After time ti, the ECU obtains a first temperature value T0 upstream of the DOC and an initial opening value A0 of the TVA measured by the temperature sensor. S20: The comparison unit of the ECU determines whether the first temperature value T0 is less than the target temperature T; S30: In response to a determination that the first temperature value T0 is less than the target temperature T, the correction unit corrects the TVA target opening value An according to the corrected opening value ΔA, the corrected time interval ΔT, and the initial opening value A0; wherein An=A0-ΔA*(nΔT), where n is an integer greater than or equal to 1; S40: After adjusting the TVA real-time opening value to be equal to the TVA target opening value An, the ECU obtains a second temperature value upstream of the DOC measured by the temperature sensor and forms a comparison value T1; wherein the TVA real-time opening value is greater than or equal to the TVA target opening value An after each correction; S50: The comparison unit of the ECU determines whether the comparison value T1 is less than the target temperature T; S60 : In response to the judgment result that the comparison value T1 is less than the target temperature T, the step of correcting the TVA target opening value An is repeated until the comparison value T1 is not less than the target temperature T.

2. The method for improving the low temperature before the DOC during parking regeneration of a vehicle according to claim 1, characterized in that: The comparison value T1 is set equal to a second temperature value upstream of the DOC measured by the temperature sensor.

3. The method for improving the low temperature before the DOC during parking regeneration of a vehicle according to claim 1, characterized in that: The comparison value T1 is equal to the difference between the second temperature value upstream of the DOC measured by the temperature sensor and the hysteresis temperature preset in the ECU.

4. The method for improving the low temperature before the DOC during parking regeneration of a vehicle according to claim 3, characterized in that: The hysteresis temperature is 10°C.

5. The method for improving the low temperature before the DOC during parking regeneration of a vehicle according to claim 1, characterized in that: The TVA initial opening value A0 ranges from 20% to 30%.

6. The method for improving the low temperature before the DOC during parking regeneration of a vehicle according to claim 1, characterized in that: The corrected opening value ΔA is the corrected fixed opening value per unit time.

7. The method for improving the low temperature before the DOC during parking regeneration of a vehicle according to claim 6, characterized in that: The modified opening value ΔA is 0.01% / s.

8. The method for improving the low temperature before the DOC during parking regeneration of a vehicle according to claim 1, characterized in that: The target temperature T ranges from 300°C to 350°C.

9. The method for improving the low temperature before the DOC during parking regeneration of a vehicle according to claim 1, characterized in that: The correction time interval ΔT ranges from 10s to 30s.

10. The method for improving the low temperature before the DOC during parking regeneration of a vehicle according to claim 1, characterized in that: The value range of ti is 100s-300s.

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