Air quantity dynamic control method and device for diesel engine

Abstract

The application discloses a kind of air quantity dynamic control method and device of diesel engine, method includes: whether it is to satisfy the activation condition of air quantity dynamic control;If yes, then according to smoke limit value, current injection quantity, current actual intake, oxygen concentration in environment, oxygen concentration in exhaust gas and maximum oxygen concentration in atmosphere obtain balanced air quantity and balanced exhaust gas recirculation rate;According to dynamic factor, balanced air quantity and balanced exhaust gas recirculation rate obtain final demand air quantity and final exhaust gas recirculation rate;According to final demand air quantity and final exhaust gas recirculation rate adjustment throttle valve actuator opening and exhaust gas recirculation system opening.The application controls the opening of TVA and EGR simultaneously in the process of vehicle acceleration and deceleration, to adjust air quantity and EGR rate simultaneously, while guaranteeing power, balance NOX and smoke.

Description

Technical Field

[0001] This application relates to the field of engine technology, and more specifically, to a method and apparatus for dynamic control of air volume in a diesel engine. Background Technology

[0002] In diesel engines using EGR (Exhaust Gas Recirculation), under steady-state conditions, controlling the EGR opening to a certain degree allows exhaust gas to recirculate through the EGR and re-enter the combustion chamber for combustion, which can reduce the engine combustion chamber temperature and effectively reduce NOx emissions.

[0003] The China VI b emission regulations for light-duty diesel engines use the WLTC cycle, which has many transient operating conditions. When the vehicle is accelerating, in order to meet the power requirements, the actual air volume needs to quickly follow the required air volume. Due to the limited intake capacity, the EGR is generally not working (off state) during the air volume following process, resulting in excessive NOx emissions. Summary of the Invention

[0004] This application provides a method and device for dynamic air volume control of a diesel engine. During vehicle acceleration and deceleration, the opening of the throttle valve actuator (TVA) and EGR is controlled simultaneously to adjust the air volume and EGR rate. While ensuring power performance, NOx and smoke are balanced so that emissions meet regulatory requirements. At the same time, excessive smoke is avoided to prevent pressure on the carbon accumulation and regeneration mileage of the DPF (Diesel Particulate Filter).

[0005] This application provides a method for dynamic control of air volume in a diesel engine, including:

[0006] Determine whether the activation conditions for dynamic air volume control are met;

[0007] If so, the balanced air volume and balanced exhaust gas recirculation rate are obtained based on the smoke opacity limit, the current fuel injection volume, the current actual intake volume, the oxygen concentration in the environment, the oxygen concentration in the exhaust, and the maximum oxygen concentration in the atmosphere.

[0008] The final required air volume and the final exhaust gas recirculation rate are obtained based on dynamic factors, balanced air volume, and balanced exhaust gas recirculation rate.

[0009] The opening degree of the throttle valve actuator and the opening degree of the exhaust gas recirculation system are adjusted according to the final required air volume and the final exhaust gas recirculation rate.

[0010] Preferably, the activation condition for dynamic air volume control is that the following requirements are met simultaneously:

[0011] The diesel engine is running;

[0012] The diesel engine is in normal mode or warm-up mode;

[0013] The turbocharger and air system are in a closed-loop state and there are no related errors;

[0014] The current water temperature, current ambient temperature, and current ambient pressure are all within the preset range.

[0015] Preferably, the balanced air volume is obtained based on the smoke opacity limit, the current fuel injection quantity, the current actual intake air volume, the oxygen concentration in the environment, the oxygen concentration in the exhaust, and the maximum oxygen concentration in the atmosphere, specifically including:

[0016] Calculate the minimum fresh air quantity based on the current fuel injection quantity and smoke opacity limit;

[0017] The minimum exhaust gas recirculation rate is calculated based on the oxygen concentration in the environment, the oxygen concentration in the exhaust gas, and the maximum oxygen concentration in the atmosphere.

[0018] The maximum fresh air volume is calculated based on the minimum exhaust gas recirculation rate and the current actual intake volume.

[0019] The balanced air volume is calculated based on the maximum fresh air volume, the minimum fresh air volume, and the balance factor.

[0020] Preferably, the exhaust gas recirculation rate after equilibrium is calculated based on the balanced air volume and the maximum fresh air volume.

[0021] Preferably, the dynamic factor is determined based on the relative pressure deviation between the actual boost pressure and the required boost pressure of the diesel engine.

[0022] This application also provides a dynamic air volume control device for a diesel engine, including a judgment module, a balance calculation module, a final quantity calculation module, and an adjustment module;

[0023] The judgment module is used to determine whether the activation conditions for dynamic air volume control are met.

[0024] The balance calculation module is used to obtain the balanced air volume and the balanced exhaust gas recirculation rate based on the smoke opacity limit, the current fuel injection volume, the current actual intake volume, the oxygen concentration in the environment, the oxygen concentration in the exhaust gas, and the maximum oxygen concentration in the atmosphere.

[0025] The final quantity calculation module is used to obtain the final required air volume and the final exhaust gas recirculation rate based on dynamic factors, balanced air volume, and balanced exhaust gas recirculation rate.

[0026] The adjustment module is used to adjust the opening of the throttle valve actuator and the opening of the exhaust gas recirculation system based on the final required air volume and the final exhaust gas recirculation rate.

[0027] Preferably, the activation condition for dynamic air volume control is that the following requirements are met simultaneously:

[0028] The diesel engine is running;

[0029] The diesel engine is in normal mode or warm-up mode;

[0030] The turbocharger and air system are in a closed-loop state and there are no related errors;

[0031] The current water temperature, current ambient temperature, and current ambient pressure are all within the preset range.

[0032] Preferably, the balance calculation module includes a minimum fresh air volume calculation module, a minimum exhaust gas recirculation rate calculation module, a maximum fresh air volume calculation module, and a balanced air volume calculation module.

[0033] The minimum fresh air volume calculation module is used to calculate the minimum fresh air volume based on the current fuel injection quantity and smoke opacity limit.

[0034] The minimum exhaust gas recirculation rate calculation module is used to calculate the minimum exhaust gas recirculation rate based on the oxygen concentration in the environment, the oxygen concentration in the exhaust gas, and the maximum oxygen concentration in the atmosphere.

[0035] The maximum fresh air volume calculation module is used to calculate the maximum fresh air volume based on the minimum exhaust gas recirculation rate and the current actual intake volume.

[0036] The balanced air volume calculation module is used to calculate the balanced air volume based on the maximum fresh air volume, the minimum fresh air volume, and the balance factor.

[0037] Preferably, the balance calculation module further includes a balance exhaust gas recirculation rate calculation module, which is used to calculate the balance exhaust gas recirculation rate based on the balance air volume and the maximum fresh air volume.

[0038] Preferably, the final quantity calculation module includes a dynamic factor determination module, which is used to determine the dynamic factor based on the relative pressure deviation between the actual boost pressure and the required boost pressure of the diesel engine.

[0039] Other features and advantages of this application will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0040] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the present application and, together with their description, serve to explain the principles of the present application.

[0041] Figure 1 A flowchart of the dynamic air volume control method for a diesel engine provided in this application;

[0042] Figure 2 A structural diagram of the dynamic air volume control device for a diesel engine provided in this application. Detailed Implementation

[0043] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present application.

[0044] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0045] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0046] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0047] This application provides a method and device for dynamic air volume control of a diesel engine, which simultaneously controls the opening of the throttle valve actuator and EGR during vehicle acceleration and deceleration to adjust the air volume and EGR rate at the same time. While ensuring power performance, it balances NOx and smoke in the WLTC cycle so that emissions can meet regulatory requirements, while avoiding excessive smoke from putting pressure on DPF carbon accumulation and regeneration mileage.

[0048] like Figure 1 As shown, the dynamic air volume control method for a diesel engine provided in this application includes:

[0049] S110: Determine whether the activation conditions for dynamic air volume control are met; if yes, start the dynamic air volume control strategy and execute S120; otherwise, end the process.

[0050] The activation conditions for dynamic air volume control are that the following requirements are met simultaneously: 1) the diesel engine is running; 2) the diesel engine is in normal mode or warm-up mode; 3) the turbocharger and air system are in closed-loop state and there are no related errors; 4) the water temperature, ambient temperature and ambient pressure are all within the preset range.

[0051] Specifically, the state of the data state machine read by the ECU (Electronic Control Unit) is used to determine whether the diesel engine is running, what operating mode it is in, whether the turbocharger and air system are in a closed-loop state, and whether there are any related errors. The current coolant temperature is obtained from the coolant temperature sensor, the current ambient temperature from the ambient temperature sensor, and the current ambient pressure from the ambient pressure sensor. The dynamic air volume control strategy is not used when the coolant and ambient temperatures are low to avoid poor engine combustion; it is also not used at high altitudes to avoid significant power loss. Therefore, the dynamic air volume control strategy is only activated when the coolant temperature, ambient temperature, and ambient pressure are all within preset ranges.

[0052] S120: Based on the smoke opacity limit Smklim_rlamset, current fuel injection quantity Injcrv_qsetunbal, current actual air intake quantity Airctl_mInt (mg / hub), and ambient oxygen concentration O 2 _renv、Oxygen concentration in exhaust gas O 2 _rexh and the maximum oxygen concentration in the atmosphere O 2 _rcon obtains the balanced air volume Airctl_mdyn and the balanced exhaust gas recirculation (EGR) rate Airctl_rdyn.

[0053] The smoke opacity limit determines the dynamic performance and smoke opacity. Generally, the smaller the smoke opacity limit, the better the dynamic performance and the greater the smoke opacity. Conversely, the larger the smoke opacity limit, the worse the dynamic performance and the smaller the smoke opacity.

[0054] As an example, based on the smoke opacity limit Smklim_rlamset, the current fuel injection quantity Injcrv_qsetunbal, the current actual air intake quantity Airctl_mInt, and the ambient oxygen concentration O 2 _renv、Oxygen concentration in exhaust gas O 2 _rexh and the maximum oxygen concentration in the atmosphere O 2 _rcon obtains the balanced air volume Airctl_mdyn, specifically including:

[0055] S1201: Calculate the minimum fresh air volume Airctl_mmin (mg / hub) based on the current fuel injection quantity Injcrv_qsetunbal and the smoke limit Smklim_rlamset.

[0056] As an example, the minimum fresh air volume Airctl_mmin is the product of the current fuel injection quantity Injcrv_qsetunbal and the smoke opacity limit Smklim_rlamset, i.e.

[0057] Airctl_mmin= Injcrv_qsetunbal* Smklim_rlamset (1)

[0058] S1202: Based on the oxygen concentration in the environment. 2 _renv、Oxygen concentration in exhaust gas O 2 _rexh and the maximum oxygen concentration in the atmosphere O 2 _rcon calculates the minimum exhaust gas recirculation rate Airctl_regrmin (%):

[0059] (2)

[0060] S1203: Calculate the maximum fresh air volume Airctl_mmax (mg / hub) based on the minimum exhaust gas recirculation rate Airctl_regrmin and the current actual intake air volume Airctl_mInt:

[0061] Airctl_mmax=(1-Airctl_regrmin)* Airctl_mInt (3)

[0062] The maximum fresh air intake volume determines the current maximum NOx emission.

[0063] S1204: Calculate the balanced air volume Airctl_mdyn (mg / hub) based on the maximum fresh air volume Airctl_mmax, the minimum fresh air volume Airctl_mmin, and the balance factor Airctl_facPrio:

[0064] Airctl_mdyn=(Airctl_mmin-Airctl_mmax)*Airctl_facPrio+Airctl_mmax (4)

[0066] The balance factor was obtained experimentally. Table 1 provides an example of the relationship between engine speed (rpm), fuel quantity (mg / hub), and balance factor.

[0067] Table 1

[0068]

[0069] Based on this, the balanced exhaust gas recirculation rate Airctl_rdyn (%) is calculated according to the balanced air volume Airctl_mdyn and the maximum fresh air volume Airctl_mmax:

[0070] Airctl_rdyn=1-Airctl_mdyn / Airctl_mmax (5)

[0071] S130: Based on the dynamic factor Airctl_facDyn, the balanced air volume Airctl_mdyn, and the balanced exhaust gas recirculation rate Airctl_rdyn, the final required air volume Airctl_mDynAdpn (mg / hub) and the final exhaust gas recirculation rate Airctl_rDynAdpn (%) are obtained.

[0072] When the boost pressure does not keep up or overshoot occurs, the calibrated steady-state fresh air demand Airctl_mdes (mg / hub) needs to be dynamically adjusted to meet the power and emission requirements. Therefore, the concept of dynamic factor Airctl_facDyn is introduced.

[0073] As an example, the dynamic factor Airctl_facDyn is determined based on the relative pressure deviation Pcr_facpdiff between the actual boost pressure Pcr_pact (hpa) and the required boost pressure Pcr_pdes (hpa) of the diesel engine.

[0074] Specifically, the relative pressure deviation Pcr_facpdiff is calculated according to the following formula:

[0075] Pcr_facpdiff=(Pcr_pdes-Pcr_pact) / Pcr_pdes (6)

[0076] Based on this, the dynamic factor Airctl_facDyn is determined by the engine speed (rpm) and the relative pressure deviation Pcr_facpdiff. Table 2 shows an example of the correspondence between engine speed, relative pressure deviation, and the dynamic factor.

[0077] Table 2

[0078]

[0079] As an example, the final required air volume Airctl_mDynAdpn is determined by the balanced air volume Airctl_mdyn, the calibrated steady-state required fresh air volume Airctl_mdes, and the dynamic factor Airctl_facDyn:

[0080] Airctl_mDynAdpn=(Airctl_mdyn-Airctl_mdes)*Airctl_facDyn+ Airctl_mdes (7)

[0082] The final exhaust gas recirculation rate Airctl_rDynAdpn is determined by the equilibrium recirculation rate Airctl_rdyn, the steady-state demand recirculation rate Airctl_rdes, and the dynamic factor Airctl_facDyn:

[0083] Airctl_rDynAdpn=(Airctl_rdyn-Airctl_rdes)*Airctl_facDyn+Airctl_rdes (8)

[0085] The calibrated steady-state fresh air demand (hereinafter referred to as steady-state air volume) and the corresponding steady-state recirculation rate were obtained by test bench calibration based on the universal characteristics of NOx and smoke opacity targets. Table 3 provides an example of the correspondence between engine speed (rpm), fuel quantity (mg / hub) and steady-state air volume.

[0086] Table 3

[0087]

[0088] Preferably, the dynamic factors are corrected based on ambient temperature, ambient pressure, and water temperature, and the final required air volume Airctl_mDynAdpn and the final exhaust gas recirculation rate Airctl_rDynAdpn are calculated using the corrected dynamic factors.

[0089] S140: Adjust the opening of the throttle valve actuator TVA and the opening of the exhaust gas recirculation system EGR according to the final required air volume Airctl_mDynAdpn and the final exhaust gas recirculation rate Airctl_rDynAdpn, so that the actual intake volume meets the requirements, thereby ensuring that the emissions and smoke opacity meet the requirements under dynamic conditions.

[0090] Based on the above-mentioned dynamic air volume control method for diesel engines, this application also provides a dynamic air volume control device for diesel engines. For example... Figure 2 As shown, the air volume dynamic control device includes a judgment module 210, a balance calculation module 220, a final quantity calculation module 230, and an adjustment module 240.

[0091] The judgment module 210 is used to determine whether the activation conditions for dynamic air volume control are met.

[0092] The balance calculation module 220 is used to obtain the balanced air volume and the balanced exhaust gas recirculation rate based on the smoke opacity limit, the current fuel injection volume, the current actual intake volume, the oxygen concentration in the environment, the oxygen concentration in the exhaust gas, and the maximum oxygen concentration in the atmosphere.

[0093] The final quantity calculation module 230 is used to obtain the final required air volume and the final exhaust gas recirculation rate based on the dynamic factor, the balanced air volume, and the balanced exhaust gas recirculation rate.

[0094] The adjustment module 240 is used to adjust the opening of the throttle valve actuator and the opening of the exhaust gas recirculation system based on the final required air volume and the final exhaust gas recirculation rate.

[0095] Preferably, the activation condition for dynamic air volume control is that the following requirements are met simultaneously:

[0096] The diesel engine is running;

[0097] The diesel engine is in normal mode or warm-up mode;

[0098] The turbocharger and air system are in a closed-loop state and there are no related errors;

[0099] The current water temperature, current ambient temperature, and current ambient pressure are all within the preset range.

[0100] Preferably, the balance calculation module 220 includes a minimum fresh air volume calculation module 2201, a minimum exhaust gas recirculation rate calculation module 2202, a maximum fresh air volume calculation module 2203, and a balanced air volume calculation module 2204.

[0101] The minimum fresh air volume calculation module 2201 is used to calculate the minimum fresh air volume based on the current fuel injection volume and smoke opacity limit.

[0102] The minimum exhaust gas recirculation rate calculation module 2202 is used to calculate the minimum exhaust gas recirculation rate based on the oxygen concentration in the environment, the oxygen concentration in the exhaust gas, and the maximum oxygen concentration in the atmosphere.

[0103] The maximum fresh air volume calculation module 2203 is used to calculate the maximum fresh air volume based on the minimum exhaust gas recirculation rate and the current actual intake volume.

[0104] The balanced air volume calculation module 2204 is used to calculate the balanced air volume based on the maximum fresh air volume, the minimum fresh air volume, and the balance factor.

[0105] Preferably, the balance calculation module 220 further includes a balance exhaust gas recirculation rate calculation module 2205, which is used to calculate the balance exhaust gas recirculation rate based on the balance air volume and the maximum fresh air volume.

[0106] Preferably, the final quantity calculation module 230 includes a dynamic factor determination module 2301, which is used to determine the dynamic factor based on the relative pressure deviation between the actual boost pressure and the required boost pressure of the diesel engine.

[0107] Preferably, the final quantity calculation module 230 further includes a correction module 2302, which is used to correct the dynamic factors according to the ambient temperature, ambient pressure, and water temperature.

[0108] The final quantity calculation module 230 also includes a final demand air volume calculation module 2303 and a final exhaust gas recirculation rate calculation module 2304. The final demand air volume calculation module 2303 calculates the final demand air volume based on the balanced air volume, the calibrated steady-state demand fresh air volume, and dynamic factors. The final exhaust gas recirculation rate calculation module 2304 calculates the final exhaust gas recirculation rate based on the balanced recirculation rate, the steady-state demand recirculation rate, and dynamic factors.

[0109] This application uses a series of state machines and sensor modules to determine when to activate the dynamic control strategy, avoiding loss of power while ensuring engine safety. It obtains the minimum and maximum fresh air volume and the corresponding EGR rate through the model, and calculates the final required air volume and the final EGR rate in real time. This ensures that emissions meet regulatory requirements while balancing smoke opacity and improving DPF regeneration range.

[0110] While specific embodiments of this application have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of this application. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of this application. The scope of this application is defined by the appended claims.

Claims

1. A method for dynamic control of air volume in a diesel engine, characterized in that, include: Determine whether the activation conditions for dynamic air volume control are met; If so, then based on the smoke opacity limit, the current fuel injection quantity, the current actual intake air quantity, the oxygen concentration in the environment, the oxygen concentration in the exhaust, and the maximum oxygen concentration in the atmosphere, the balanced air volume and the balanced exhaust gas recirculation rate are obtained, among which, Calculate the minimum fresh air quantity based on the current fuel injection quantity and the smoke opacity limit; The minimum exhaust gas recirculation rate is calculated based on the oxygen concentration in the environment, the oxygen concentration in the exhaust gas, and the maximum oxygen concentration in the atmosphere. The maximum fresh air volume is calculated based on the minimum exhaust gas recirculation rate and the current actual intake volume; The balanced air volume is calculated based on the maximum fresh air volume, the minimum fresh air volume, and the balance factor. The final required air volume and the final exhaust gas recirculation rate are obtained based on the dynamic factor, the balanced air volume, and the balanced exhaust gas recirculation rate, wherein the dynamic factor is determined based on the relative pressure deviation between the actual boost pressure and the required boost pressure of the diesel engine. The opening degree of the throttle valve actuator and the opening degree of the exhaust gas recirculation system are adjusted according to the final required air volume and the final exhaust gas recirculation rate. Specifically, during vehicle acceleration and deceleration, the opening of the throttle valve actuator and the exhaust gas recirculation system are controlled simultaneously to adjust the air volume and exhaust gas recirculation rate at the same time, so as to balance NOx and smoke opacity while ensuring power performance.

2. The method for dynamic air volume control of a diesel engine according to claim 1, characterized in that, The activation condition for dynamic air volume control is that the following requirements must be met simultaneously: The diesel engine is running; The diesel engine is in normal mode or warm-up mode; The turbocharger and air system are in a closed-loop state and there are no related errors; The current water temperature, current ambient temperature, and current ambient pressure are all within the preset range.

3. The method for dynamic air volume control of a diesel engine according to claim 1, characterized in that, The balanced exhaust gas recirculation rate is calculated based on the balanced air volume and the maximum fresh air volume.

4. A dynamic air volume control device for a diesel engine, characterized in that, It includes a judgment module, a balance calculation module, a final quantity calculation module, and an adjustment module; The judgment module is used to determine whether the activation conditions for dynamic air volume control are met. The balance calculation module is used to obtain the balanced air volume and the balanced exhaust gas recirculation rate based on the smoke opacity limit, the current fuel injection quantity, the current actual intake air volume, the oxygen concentration in the environment, the oxygen concentration in the exhaust gas, and the maximum oxygen concentration in the atmosphere. The balance calculation module includes a minimum fresh air volume calculation module, a minimum exhaust gas recirculation rate calculation module, a maximum fresh air volume calculation module, and a balanced air volume calculation module. The minimum fresh air volume calculation module is used to calculate the minimum fresh air volume based on the current fuel injection volume and the smoke limit. The minimum exhaust gas recirculation rate calculation module is used to calculate the minimum exhaust gas recirculation rate based on the oxygen concentration in the environment, the oxygen concentration in the exhaust gas, and the maximum oxygen concentration in the atmosphere. The maximum fresh air volume calculation module is used to calculate the maximum fresh air volume based on the minimum exhaust gas recirculation rate and the current actual air intake volume. The balanced air volume calculation module is used to calculate the balanced air volume based on the maximum fresh air volume, the minimum fresh air volume, and the balance factor. The final quantity calculation module is used to obtain the final required air quantity and the final exhaust gas recirculation rate based on the dynamic factor, the balanced air quantity, and the balanced exhaust gas recirculation rate. The final quantity calculation module includes a dynamic factor determination module, which is used to determine the dynamic factor based on the relative pressure deviation between the actual boost pressure and the required boost pressure of the diesel engine. The adjustment module is used to adjust the opening degree of the throttle valve actuator and the opening degree of the exhaust gas recirculation system according to the final required air volume and the final exhaust gas recirculation rate. Specifically, during vehicle acceleration and deceleration, the opening of the throttle valve actuator and the exhaust gas recirculation system are controlled simultaneously to adjust the air volume and exhaust gas recirculation rate at the same time, so as to balance NOx and smoke opacity while ensuring power performance.

5. The dynamic air volume control device for a diesel engine according to claim 4, characterized in that, The activation condition for dynamic air volume control is that the following requirements must be met simultaneously: The diesel engine is running; The diesel engine is in normal mode or warm-up mode; The turbocharger and air system are in a closed-loop state and there are no related errors; The current water temperature, current ambient temperature, and current ambient pressure are all within the preset range.

6. The dynamic air volume control device for a diesel engine according to claim 5, characterized in that, The balance calculation module also includes a balance exhaust gas recirculation rate calculation module, which is used to calculate the balance exhaust gas recirculation rate based on the balance air volume and the maximum fresh air volume.

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