Control method for realizing oil saving of diesel engine through non-inductive regeneration mode

Abstract

The invention relates to a control method for realizing fuel saving of a diesel engine through a non-inductive regeneration mode, and relates to the technical field of diesel engines. When the carbon loading capacity exceeds a first threshold value, judging whether a triggering condition meets a non-inductive regeneration requirement or not; if yes, a non-inductive regeneration mode is executed, specifically, the exhaust temperature is controlled to be the first temperature, carbon particle oxidation is conducted on the particle trap till the carbon loading amount is reduced to a second threshold value, and the second threshold value is lower than the first threshold value; if not, a normal regeneration mode is executed, specifically, the exhaust temperature is increased to a second temperature higher than the first temperature, carbon particle oxidation is conducted on the particle trap till the carbon loading amount is reduced to a third threshold value, and the third threshold value is lower than the second threshold value; and recording the non-inductive regeneration execution times, and resetting the times after the normal regeneration mode is completed. According to the invention, multiple times of low-temperature non-inductive regeneration are implemented in a high-carbon loading interval to replace partial high-temperature regeneration, so that the regeneration period is prolonged, the fuel utilization rate is improved, and the purpose of saving oil is achieved.

Description

Technical Field

[0001] This invention relates to the field of diesel engine technology with particulate traps, and in particular to a control method for achieving fuel saving in diesel engines through a sensorless regeneration mode. Background Technology

[0002] With the upgrading of national environmental protection regulations, diesel engines that meet the China VI emission standards must be equipped with a diesel particulate filter (DPF) to capture particulate matter, mainly carbon soot particles, in the diesel engine exhaust. As the amount of carbon soot particles increases to a certain level, it will increase the exhaust back pressure, which will worsen the combustion of the diesel engine and lead to increased fuel consumption. Therefore, the carbon deposits in the DPF need to be oxidized periodically by increasing the exhaust temperature (referred to as active regeneration), generating carbon dioxide which is discharged with the exhaust gas.

[0003] The existing active regeneration method triggers active regeneration when the carbon load model calculated by the ECU reaches a certain level. This is achieved by controlling the injectors to add one or two stages of fuel injection during the later part of the exhaust stroke (referred to as post-injection). The fuel injected into the cylinder generates incompletely burned hydrocarbons, which are then burned in the DOC (Decay-Oxidation Catalytic Reactor) along with the exhaust gas. This raises the exhaust temperature to a level sufficient to oxidize soot particles, and the process ends when the amount of soot particles remaining in the DPF is reduced to a very low level. To minimize the regeneration time and ensure complete oxidation of soot particles, the exhaust temperature entering the DPF is maintained at around 600°C. For engines using Selective Catalytic Reduction (SCR) technology, active regeneration also serves to remove urea crystals and desulfurize the SCR carrier, thus requiring periodicity. However, the cycle for removing urea crystals and desulfurizing the SCR carrier is much longer than the carbon deposit regeneration cycle.

[0004] Frequent triggering of the aforementioned active regeneration will increase the amount of fuel injected after the exhaust to maintain exhaust temperature, thus increasing fuel consumption. Furthermore, high temperatures significantly impact the lifespan of the DPF (Diesel Particulate Filter), accelerating its degradation. Additionally, high exhaust temperatures during vehicle operation are dangerous, as they can easily ignite flammable materials near the aftertreatment system, posing a significant safety hazard. Summary of the Invention

[0005] The purpose of this invention is to provide a control method for achieving fuel saving in diesel engines through a sensorless regeneration mode, in order to solve the problems of increased fuel consumption, shortened service life, and safety hazards caused by frequent high-temperature active regeneration of existing diesel particulate filters. By implementing multiple low-temperature sensorless regenerations in the high carbon load range to replace part of the high-temperature regeneration, the regeneration cycle is extended and the fuel utilization rate is improved, thereby achieving the goal of fuel saving.

[0006] To achieve the above objectives, the present invention provides a control method for achieving fuel saving in a diesel engine through a sensorless regeneration mode, comprising the following steps: Obtain the carbon loading of the particulate filter; When the carbon load exceeds the first threshold, determine whether the triggering conditions meet the requirements for sensorless regeneration. If the conditions are met, the sensorless regeneration mode is executed: the exhaust temperature is controlled to the first temperature, and carbon particles are oxidized in the particulate filter until the carbon load is reduced to the second threshold, which is lower than the first threshold. If the conditions are not met, the normal regeneration mode is executed: the exhaust temperature is raised to a second temperature higher than the first temperature, and carbon particles are oxidized in the particulate filter until the carbon load is reduced to a third threshold, which is lower than the second threshold. Record the number of times seamless regeneration is performed, and reset the count to zero after the normal regeneration mode is completed.

[0007] Preferably, the triggering conditions include: The pressure difference between the front and rear ends of the particulate filter did not exceed the clogging threshold. The nitrogen oxide conversion efficiency of the selective catalytic reduction system was not lower than the crystallization risk threshold; The cumulative number of seamless regeneration operations has not exceeded the preset threshold.

[0008] Preferably, in the non-sensory regeneration mode, based on the exponential relationship between carbon particle oxidation rate and carbon loading and temperature, an effective oxidation reaction rate is maintained when the carbon loading is higher than a second threshold.

[0009] Preferably, the exhaust temperature control in the sensorless regeneration mode is achieved by adjusting the intake air volume through the throttle valve and / or adjusting the fuel injection parameters, wherein the fuel injection parameter adjustment includes retarding the injection advance angle, reducing the common rail pressure, and / or performing a single, small-volume, far-end injection.

[0010] Preferred options also include: When the engine starts, the carbon load and the cumulative number of sensorless regeneration cycles are read from the memory; When the engine is powered off, the current carbon load and the cumulative number of sensorless regeneration cycles are stored in the memory.

[0011] Preferably, the memory is an electrically erasable programmable read-only memory.

[0012] Preferably, the first threshold is the minimum carbon load at which the particulate filter must be regenerated, which is related to the characteristics and volume of the particulate filter carrier material, and is set to 3 g / L.

[0013] Preferably, the first temperature is 550℃ and the second temperature is 625℃.

[0014] Preferably, the second threshold is set to 25 grams, and when the carbon loading is higher than 25 grams, the carbon particle oxidation rate is maintained above 20 mg / s; the third threshold is set to 6 grams.

[0015] Preferably, the preset number of times threshold is 3 times.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects: In this invention, without affecting the normal regeneration process, multiple low-temperature, non-sensory regenerations are performed in the high carbon load region, increasing the time interval between two normal regenerations and extending the regeneration cycle. Furthermore, because non-sensory regeneration occurs in the high carbon load region, the fuel has a higher oxidation efficiency for carbon particles, improving fuel utilization and achieving fuel saving. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the main process of a control method for achieving fuel saving in a diesel engine through a sensorless regeneration mode according to the present invention; Figure 2 This is a schematic diagram of the oxidation reaction rate fitting curve under different carbon deposit amounts in the control method for achieving fuel saving in diesel engines through a sensorless regeneration mode according to the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] This invention discloses a control method for achieving fuel saving in diesel engines through a sensorless regeneration mode. The core of this method lies in utilizing the characteristic that the carbon particle oxidation efficiency of diesel engines is significantly improved in the high carbon load range. By entering the sensorless regeneration mode multiple times in the high carbon load range, low-temperature sensorless regeneration replaces part of the high-temperature active regeneration, thereby extending the regeneration cycle while improving fuel efficiency during regeneration and reducing fuel consumption, thus achieving the purpose of fuel saving.

[0020] Specifically, the present invention includes the following steps: Step 1: After the engine is powered on and started, the electronic control unit (engine controller, ECU) first reads the model carbon load value and the number of sensorless regeneration accumulations at the end of the previous working cycle from the electrically erasable programmable read-only memory (EEPROM). These two key parameters are recorded and stored in the memory in real time each time the engine is powered off to ensure data continuity. Then the engine enters normal operation, and the model carbon load is integrated according to the real-time operating parameters to dynamically reflect the carbon deposits inside the DPF, proceeding to Step 2. Step 2: Determine the carbon load of the model. When the integral value of the carbon load exceeds the first threshold M1, the system initiates the regeneration judgment logic. The M1 value represents the minimum carbon load at which the DPF must be regenerated. Its specific value is directly related to the characteristics and volume of the DPF carrier material and is set to 3g / L. Taking a commercially available 7L engine as an example, its M1 value is set to 30 grams. If the current carbon load of the model does not exceed the first threshold M1, the engine maintains its normal operating mode without change, and the carbon load of the model continues to accumulate. Once the carbon load of the model exceeds the M1 value, proceed to step 3. Step 3: A comprehensive assessment of the engine status is conducted. If the pressure difference between the DPF front and rear ends measured by the sensor exceeds the pre-calibrated blockage threshold (this blockage threshold is obtained through bench testing; specifically, the full-condition map is run and the pressure difference value at each operating point is recorded when the carbon deposit inside the DPF reaches 40 grams, thus forming a blockage judgment benchmark under different operating conditions), or the nitrogen oxide conversion efficiency calculated by the selective catalytic reduction system is lower than the efficiency threshold when there is a risk of crystallization (this conversion efficiency threshold is selected as 50% of the normal efficiency value at the operating point as the judgment basis; according to actual test experience, the amount of crystals generated at this time can be completely removed by one normal regeneration process), or the number of times the sensorless regeneration mode has been executed has exceeded three; if any of the above conditions are met, it is determined that high-temperature normal regeneration must be triggered to ensure DPF reliability, and the sensorless regeneration will be skipped and the high-temperature regeneration process in Step 7 will be directly entered; otherwise, the sensorless regeneration mode in Step 4 will be entered. Step 4, in the sensorless regeneration mode, the chemical reaction equations for the oxidation of carbon particles inside the DPF are as follows: C + O₂ → CO₂ This chemical reaction process conforms to the Arrhenius kinetic equation and can be expressed as: R=k*exp((-Ea) / RT)*Co2 Given the sufficient oxygen concentration and relatively small reactive carbon loading in diesel engine exhaust, it is reasonable to assume that all carbon particles can fully contact oxygen. Therefore, the kinetic equation can be simplified to: Rpm=A*exp((-Ea) / RT)*Mpm Where Rpm represents the DPF regeneration rate (unit: mg / s), Mpm represents the current carbon loading (unit: mg), and A is a reaction constant that is only related to the DPF structural size; The equation clearly reveals an exponential relationship between reaction rate and temperature at a given carbon loading. To obtain accurate reaction rate data, the aftertreatment system of the 7-liter engine was quantitatively analyzed for carbon buildup. Oxidation was then performed at different constant temperatures with equal time intervals, and the carbon content was precisely weighed. This yielded multiple sets of carbon consumption data under various temperature and carbon buildup conditions. Oxidation rate curves under different temperatures and carbon loadings were then fitted. Figure 2As shown; Based on the maximum exhaust temperature boundary corresponding to the external characteristic curve of this model, a temperature that neither exceeds the temperature limit nor fails to maintain a considerable oxidation rate is selected as the target temperature for imperceptible regeneration. For example, 550℃ is selected as the target temperature for imperceptible regeneration. According to the analysis of the oxidation rate curve, at this temperature, when the carbon load is 25 grams, an oxidation rate of about 20 mg / s can still be achieved. However, when the carbon load is less than 25 grams, the oxidation rate drops significantly. Therefore, 25 grams of carbon load is set as the marker point for the completion of imperceptible regeneration. Areas with carbon loads higher than this constitute the high-efficiency oxidation reaction zone. The increase in exhaust temperature under this state is relatively small. Under high load conditions, the exhaust temperature can be raised to the target value by appropriately reducing the fresh intake air volume through throttle control. Under medium and low load conditions, in addition to the above intake control methods, the target exhaust temperature can also be achieved by combining injection advance angle retarding, common rail pressure reduction, and single small amount of far-field injection. Since the amount of fuel injected after the injection is small during this process, it can achieve full oxidation in the oxidation catalyst. The content of unburned hydrocarbons in the exhaust is extremely low, and there is no risk of high-temperature ignition of exhaust. Therefore, there is no need to illuminate the high-temperature warning light on the instrument panel, and the user cannot perceive that the regeneration process is in progress. As the imperceptible regeneration proceeds, the carbon load of the model gradually decreases, and the process proceeds to step 5. Step 5: As the seamless regeneration continues, the model carbon load gradually decreases. It is continuously determined whether the current model carbon load is still higher than the second threshold M2 (the value of M2 is the carbon load corresponding to the aforementioned seamless regeneration completion mark, which is set to 25 grams in this example). If the model carbon load is not lower than M2, the seamless regeneration mode continues to run, and the model carbon load continues to be integrated. Once the model carbon load drops below M2, proceed to step 6. Step 6: Determine that the sensorless regeneration is complete. At this time, the cumulative number of sensorless regenerations is increased by one and the updated value is stored in the electrically erasable programmable read-only memory. Then, the carbon loading of the model continues to be integrated and the logic returns to the initial judgment in Step 2. Step 7: When normal regeneration is triggered due to excessive differential pressure, low SCR efficiency, or excessive number of sensorless regeneration cycles, a higher exhaust temperature level needs to be established (the DPF inlet exhaust temperature needs to be maintained at approximately 625°C). During the regeneration process, the high temperature indicator light on the dashboard will remain on to warn the user of the risk of high exhaust temperature. The normal regeneration process continues until the model carbon load drops below the third threshold M3 (M3 is the marker carbon load for the completion of normal regeneration, usually set at a low level, approximately 6 grams). After normal regeneration is completed, the accumulated number of sensorless regeneration cycles will be cleared and re-stored in the EEPROM, thus completing a full regeneration cycle. Subsequently, the model carbon load will be re-integrated from M3 and the process will return to Step 2 to enter the next cycle judgment.

[0021] Through the above control method, although the carbon load of the engine continues to increase during actual use, the regeneration cycle is significantly extended after adopting the logic control of the present invention, which greatly increases the interval between the two instrument panel reminders of high regeneration temperature alarms; at the same time, by utilizing the non-sensory regeneration characteristics in the high carbon load range, the purpose of carbon particle oxidation can be achieved by heating the exhaust with less fuel consumption, which effectively improves fuel economy and improves engine economic performance.

[0022] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A control method for achieving fuel saving in a diesel engine through a sensorless regeneration mode, characterized in that, Includes the following steps: Obtain the carbon loading of the particulate filter; When the carbon load exceeds the first threshold, determine whether the triggering conditions meet the requirements for sensorless regeneration. If the conditions are met, the sensorless regeneration mode is executed: the exhaust temperature is controlled to the first temperature, and carbon particles are oxidized in the particulate filter until the carbon load is reduced to the second threshold, which is lower than the first threshold. If the conditions are not met, the normal regeneration mode is executed: the exhaust temperature is raised to a second temperature higher than the first temperature, and carbon particles are oxidized in the particulate filter until the carbon load is reduced to a third threshold, which is lower than the second threshold. Record the number of times seamless regeneration is performed, and reset the count to zero after the normal regeneration mode is completed.

2. The control method for achieving fuel saving in a diesel engine through a sensorless regeneration mode according to claim 1, characterized in that, Triggering conditions include: The pressure difference between the front and rear ends of the particulate filter did not exceed the clogging threshold. The nitrogen oxide conversion efficiency of the selective catalytic reduction system was not lower than the crystallization risk threshold; The cumulative number of seamless regeneration operations has not exceeded the preset threshold.

3. The control method for achieving fuel saving in a diesel engine through a sensorless regeneration mode according to claim 2, characterized in that, In the sensorless regeneration mode, based on the exponential relationship between carbon particle oxidation rate and carbon loading and temperature, an effective oxidation reaction rate is maintained when the carbon loading is higher than the second threshold.

4. The control method for achieving fuel saving in a diesel engine through a sensorless regeneration mode according to claim 3, characterized in that, The exhaust temperature control in the sensorless regeneration mode is achieved by adjusting the intake air volume through the throttle valve and / or adjusting the fuel injection parameters. The fuel injection parameter adjustments include retarding the injection advance angle, reducing the common rail pressure, and / or performing a single, small-volume, far-field injection.

5. The control method for achieving fuel saving in a diesel engine through a sensorless regeneration mode according to claim 4, characterized in that, Also includes: When the engine starts, the carbon load and the cumulative number of sensorless regeneration cycles are read from the memory; When the engine is powered off, the current carbon load and the cumulative number of sensorless regeneration cycles are stored in the memory.

6. The control method for achieving fuel saving in a diesel engine through a sensorless regeneration mode according to claim 5, characterized in that, The memory is an electrically erasable programmable read-only memory.

7. A control method for achieving fuel saving in a diesel engine through a sensorless regeneration mode according to any one of claims 1-5, characterized in that, The first threshold is the minimum carbon load at which the particulate filter must be regenerated. It is related to the characteristics and volume of the particulate filter carrier material and is set at 3 g / L.

8. The control method for achieving fuel saving in a diesel engine through a sensorless regeneration mode according to claim 7, characterized in that, The first temperature is 550℃, and the second temperature is 625℃.

9. A control method for achieving fuel saving in a diesel engine through a sensorless regeneration mode according to claim 8, characterized in that, The second threshold is set at 25 grams, and when the carbon loading is higher than 25 grams, the carbon particle oxidation rate is maintained above 20 mg / s; the third threshold is set at 6 grams.

10. A control method for achieving fuel saving in a diesel engine through a sensorless regeneration mode according to claim 9, characterized in that, The preset threshold for the number of attempts is 3.

Images