Intelligent emission heat management control method for hybrid power engine

Abstract

The invention discloses an intelligent emission heat management control method for a hybrid power engine, and relates to an engine heat management technology, when the engine enters an idling operation state, the idling operation duration of the engine and the upstream temperature of an SCR unit are obtained, meanwhile, the change slope of the SCR unit is obtained according to the upstream temperature of the SCR unit, and in the idling operation period, the temperature of the SCR unit is adjusted according to the change slope. If the upstream temperature of the SCR unit is lower than the set temperature threshold value and the change slope is lower than the set slope threshold value, when the running duration is the end point of the idle running cycle, the idle speed of the engine is increased according to a preset rotating speed value; and the charging demand state of the battery is predicted, when the charging demand state shows that the battery has the charging demand, whether the upstream temperature of the SCR unit is lower than a set temperature threshold value or not is judged, and if yes, the rotating speed of the engine is increased, so that the idling running state is converted into the engine increasing idling heating working condition. According to the system, efficient heat management can be carried out on the engine, effective control over NOx exhaust emission is achieved, and then optimal control over emission is achieved.

Description

Technical Field

[0001] The present invention relates to engine thermal management technology, and more particularly, to an intelligent emission thermal management control method for a hybrid power engine. Background Art

[0002] Hybrid vehicles utilize both engine and electric motor drive. During operation, they select a specific operating mode based on road conditions, speed requirements, and battery status. These modes can be single-engine, single-electric motor, or a combination of both. Generally speaking, hybrid engine operating modes are demanding, with frequent engine starts and stops. This results in significant temperature fluctuations in the aftertreatment system connected to the engine exhaust. Exhaust treatment relies on the exhaust temperature of the aftertreatment system. Drastic temperature fluctuations and low exhaust temperatures (<200°C) can result in a significant amount of exhaust pollutants being released into the atmosphere without being fully treated, causing pollution.

[0003] Currently, regulations on mobile pollution sources are becoming increasingly stringent. The Euro VII regulation sets a limit of 0.26g / kWh for PEMS emissions of carbon oxides (NOx), which is 58% lower than that of Euro VI. Figure 1 This is a PEMS test profile for a commercial hybrid bus (70% urban + 30% suburban). The engine remains idle throughout the PEMS test (to account for engine air compressor inflation and air conditioning heating / cooling). The HCU control revealed two segments of the profile where the engine idled continuously for 20 minutes, and four segments where it idled for nearly 10 minutes. This extended idling period inherently lowers the engine's exhaust temperature, and coupled with heat losses in the exhaust pipe, the exhaust temperature by the aftertreatment catalyst drops to a very low level (≤160°C). Due to the nature of hybrid engine operation, when the HCU generates power, it sends a command to the ECU, suddenly increasing the engine speed and load to power generation mode. This shift in operating conditions makes NOx control particularly challenging. The engine exhaust temperature rises slowly, and the relatively low exhaust temperature (<200°C) results in a significant amount of NOx being released into the atmosphere without being fully treated, causing pollution.

[0004] Therefore, when the vehicle's engine is in operation due to air compressor inflation, air conditioning heating / cooling, etc., but not generating electricity, that is, when the engine runs in idle condition for a long time, how the hybrid system controller (HCU), engine control unit (ECU), and engine management system (EMS) can work together efficiently becomes the key to emission control. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the deficiencies of the existing technology and provide a hybrid engine intelligent emission thermal management control method to achieve effective control of NOx tail emissions.

[0006] The hybrid engine intelligent emission thermal management control method described in the present invention sets an idle operation cycle. When the engine enters the idle operation state, the SCR temperature monitoring strategy and the battery charging demand monitoring strategy are simultaneously executed;

[0007] The SCR temperature monitoring strategy comprises: obtaining the engine idling operation duration and the upstream temperature of the SCR unit, and obtaining a change slope of the upstream temperature of the SCR unit according to the upstream temperature of the SCR unit; and if, during the idling operation period, the upstream temperature of the SCR unit is lower than a set temperature threshold and the change slope is lower than a set slope threshold, then when the operation duration reaches the end of the idling operation period, increasing the engine idling speed by a preset speed value;

[0008] The charging demand monitoring strategy is as follows: predicting the battery's charging demand state; when the charging demand state indicates that the battery has a charging demand, determining whether the upstream temperature of the SCR unit is lower than a set temperature threshold; if so, increasing the engine speed to switch from an idle operation state to an engine-boosted idle heating operation state.

[0009] Preferably, when executing the SCR temperature monitoring strategy, if a sudden increase in the engine speed is detected, the current speed is collected, and the engine operating condition is identified based on the current speed, and then it is determined whether the time period corresponding to the sudden increase in speed is to be eliminated based on the identification result.

[0010] Preferably, the working condition identification is specifically:

[0011] The current speed is compared with the set speed threshold. If the current speed is less than or equal to the speed threshold, it is determined that the speed has not changed suddenly, and the running time continues to be measured; if the current speed is greater than the speed threshold, the timing of the running time is paused, and the time period corresponding to the speed greater than the speed threshold is eliminated, and the running time continues to be measured.

[0012] Preferably, the rotation speed value is +200r / min to +300r / min.

[0013] Preferably, the temperature threshold is below 160°C.

[0014] Preferably, when executing the charging demand monitoring strategy, when the upstream temperature of the SCR unit reaches a high temperature threshold, the engine is controlled to run according to the demand of the VCU.

[0015] Preferably, the high temperature threshold is above 220°C.

[0016] Beneficial effects

[0017] The advantages of the present invention are:

[0018] 1. A preventive SCR temperature monitoring strategy is adopted to increase the exhaust temperature by increasing the idle speed, preventing the exhaust pollutants from being discharged into the atmosphere due to the exhaust temperature being too low when the engine enters other operating conditions.

[0019] 2. The battery charging demand is predicted through a charging demand monitoring strategy. Based on the prediction results, the engine is put into a heating state in advance to carry out efficient thermal management of the engine, achieve effective control of NOx tail emissions, and achieve optimal emission control. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a data curve diagram of the PEMS emission test process for hybrid buses;

[0021] Figure 2 This is a flow chart of the hybrid engine intelligent emission thermal management control method of the present invention. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with the embodiments, but this does not constitute any limitation to the present invention. Any limited number of modifications made by anyone within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0023] See Figure 2 The present invention provides a hybrid engine intelligent emission thermal management control method, which sets an idle operation cycle. When the engine enters the idle operation state, the SCR temperature monitoring strategy and the battery charging demand monitoring strategy are simultaneously executed.

[0024] The SCR temperature monitoring strategy involves obtaining the engine's idle operating time and the temperature upstream of the SCR unit (i.e., T6 temperature), and simultaneously determining the slope of change based on the upstream temperature. During the idle operating cycle, if the upstream temperature of the SCR unit falls below a set temperature threshold (e.g., below 160°C) and the slope of change falls below a set slope threshold, the engine's idle speed is increased by a preset speed value when the engine reaches the end of the idle operating cycle. This strategy is a preventative measure. If the engine idles for an extended period, a phased idle speed increase is implemented to raise the exhaust temperature, preventing exhaust pollutants from being fully treated and discharged into the atmosphere due to excessively low exhaust temperatures when the engine enters other operating modes. Increasing the engine idle speed will cause the T6 temperature to rise, so it is necessary to monitor whether it exceeds the high temperature threshold. If so, engine operation is controlled according to the VCU's requirements.

[0025] The rotation speed is between +200 r / min and +300 r / min, which can effectively increase the upstream temperature of the SCR unit.

[0026] When executing the SCR temperature monitoring strategy, if a sudden increase in engine speed is detected, the current speed is collected and the engine operating condition is identified based on the current speed. The identification result then determines whether to exclude the time period corresponding to the sudden speed increase. This approach is primarily intended to more accurately identify the operating condition and avoid the problem of the system mistakenly interpreting a sudden speed increase as the engine exiting idle mode, causing the strategy to exit.

[0027] In this embodiment, the working condition identification is specifically as follows:

[0028] The current speed is compared with the set speed threshold. If the current speed is less than or equal to the speed threshold, it is determined that there is no sudden speed change, and the running time measurement continues. If the current speed is greater than the speed threshold, the running time measurement is paused, and the period corresponding to the speed exceeding the threshold is eliminated, and the running time measurement continues. In other words, some low-speed and low-load operating conditions, which require the driver to briefly press the accelerator and do not cause a significant speed change, should not be considered as a sudden speed change. However, when the hybrid system requires a short period of engine intervention, the engine speed will increase significantly, and this operating condition should be eliminated.

[0029] In this embodiment, the charging demand monitoring strategy is to predict the battery's charging demand state. When the charging demand state indicates a battery charging demand, the system determines whether the temperature upstream of the SCR unit is below a set temperature threshold. If so, the engine speed is increased to transition from idle operation to an engine boosted idle heating condition. In this embodiment, the engine boosted idle heating condition can increase the engine idle speed by a preset speed value in accordance with the SCR temperature monitoring strategy, or it can be calibrated to a higher idle speed to rapidly increase exhaust temperature. By predicting the battery charging demand, the engine's operating condition can be known in advance, allowing for efficient thermal management of the engine to be implemented in advance, achieving effective NOx tailpipe emissions control and optimal emissions control. The battery charging demand state prediction method can utilize existing prediction models or a battery charge determination method. For example, when the battery charge falls below a set threshold, a battery charging demand is predicted.

[0030] When executing the charging demand monitoring strategy, when the upstream temperature of the SCR unit reaches a high temperature threshold (such as ≥220°C), the engine operation is controlled according to the needs of the VCU, the management intensity of the heating mode is reduced, and optimal emission control is achieved while ensuring NOx emission compliance.

[0031] The above is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the structure of the present invention. These modifications and improvements will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. A hybrid engine intelligent exhaust thermal management control method, characterized in that: Set the idle operation cycle. When the engine enters the idle operation state, the SCR temperature monitoring strategy and the battery charging demand monitoring strategy are executed simultaneously. The SCR temperature monitoring strategy comprises: obtaining the engine idling operation duration and the upstream temperature of the SCR unit, and obtaining a change slope of the upstream temperature of the SCR unit according to the upstream temperature of the SCR unit; and if, during the idling operation period, the upstream temperature of the SCR unit is lower than a set temperature threshold and the change slope is lower than a set slope threshold, then when the operation duration reaches the end of the idling operation period, increasing the engine idling speed by a preset speed value; The charging demand monitoring strategy is as follows: predicting the battery's charging demand state; when the charging demand state indicates that the battery has a charging demand, determining whether the upstream temperature of the SCR unit is lower than a set temperature threshold; if so, increasing the engine speed to shift the engine from an idle operation state to an engine boosted idle heating operation state.

2. The hybrid engine intelligent exhaust thermal management control method according to claim 1, characterized in that: When executing the SCR temperature monitoring strategy, if a sudden increase in the engine speed is detected, the current speed is collected, and the engine operating condition is identified based on the current speed. Then, based on the identification result, it is determined whether the time period corresponding to the sudden increase in the speed is to be eliminated.

3. The hybrid engine intelligent exhaust thermal management control method according to claim 2, characterized in that: The working condition identification is specifically as follows: Comparing the current speed with a set speed threshold, if the current speed is less than or equal to the speed threshold, it is determined that the speed has not changed suddenly, and the running time is continuously counted; If the current rotational speed is greater than the rotational speed threshold, the timing of the running time is suspended, and after the time period corresponding to the rotational speed greater than the rotational speed threshold is eliminated, the running time continues to be counted.

4. The hybrid engine intelligent exhaust thermal management control method according to claim 1, characterized in that: The rotation speed value is +200r / min to +300r / min.

5. The hybrid engine intelligent exhaust thermal management control method according to claim 1, characterized in that: The temperature threshold is below 160°C.

6. The hybrid engine intelligent exhaust thermal management control method according to claim 1, characterized in that: When the charging demand monitoring strategy is executed, when the temperature upstream of the SCR unit reaches a high temperature threshold, the engine is controlled to run according to the demand of the VCU.

7. The hybrid engine intelligent exhaust thermal management control method according to claim 6, characterized in that: The high temperature threshold is above 220°C.

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