Control method and system for increasing exhaust temperature of a diesel engine

Abstract

The application discloses a control method and system for improving diesel engine exhaust temperature, wherein the control method for improving diesel engine exhaust temperature comprises the following steps: S100, initializing temperature conditions, and judging whether the engine water temperature and the SCR inlet temperature are less than preset values; S200, if less than the preset values, entering a thermal management mode; S300, continuously monitoring whether the SCR inlet temperature is greater than or equal to a calibration value; and S400, if greater than the calibration value, exiting the thermal management mode and entering a normal mode. Therefore, the control method for improving diesel engine exhaust temperature can improve the temperature quickly, and can make the SCR catalyst always be in an efficient temperature range. In different engine operating states, different methods for improving exhaust temperature are adopted, the NOx emission is reduced, the additional fuel consumption is small, and the method is universal and can be applied to all platform diesel engines with the configuration.

Description

Technical Field

[0001] This invention relates to the field of engine technology, and in particular to a control method and system for increasing the exhaust temperature of a diesel engine. Background Technology

[0002] China VI engines generally adopt the technical route of DOC+DPF+SCR+ASC. Due to the characteristics of SCR catalyst and urea solution, the conversion efficiency is low and NOx emissions are high under operating conditions below 200℃. In order to further reduce NOx emissions during vehicle operation, how to increase exhaust temperature has become a key technology for future diesel engine technology breakthroughs.

[0003] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide a control method and system for increasing the exhaust temperature of a diesel engine. The method increases the temperature quickly and keeps the SCR catalytic converter in its efficient temperature range. Different methods for increasing the exhaust temperature are used under different engine operating conditions. This reduces NOx emissions while minimizing additional fuel consumption. The method is also universal and applicable to all platform diesel engines of this configuration.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a control method for increasing the exhaust temperature of a diesel engine, comprising: step S100, initializing temperature conditions and determining whether the engine coolant temperature and SCR inlet temperature are less than preset values; step S200, if less than the preset values, entering a thermal management mode; step S300, continuously monitoring whether the SCR inlet temperature is greater than or equal to a calibrated value; step S400, if greater than the calibrated value, exiting the thermal management mode and entering a normal mode.

[0006] In one embodiment of the present invention, the initial temperature conditions include initializing engine speed, engine circulating oil volume, ambient temperature, ambient pressure, vehicle gear, vehicle speed, and urea injection status.

[0007] In one embodiment of the present invention, determining whether the engine coolant temperature and the SCR inlet temperature are less than preset values ​​specifically involves determining whether the engine coolant temperature is less than 70°C and whether the SCR inlet temperature is less than 210°C.

[0008] In one embodiment of the present invention, the thermal management mode includes a first thermal management mode, a second thermal management mode, and a third thermal management mode.

[0009] In one embodiment of the present invention, step S200 includes:

[0010] If it is less than the preset value, enter the first thermal management mode or the third thermal management mode;

[0011] In the first thermal management mode, if the engine coolant temperature is ≥70℃ and 260℃ ≥ SCR inlet temperature ≥210℃, the second thermal management mode is entered.

[0012] In the second thermal management mode, if the engine coolant temperature is ≥70℃ and the SCR inlet temperature is <210℃, the first thermal management mode is entered.

[0013] In the first thermal management mode or the second thermal management mode, if the engine coolant temperature is <70°C and the SCR inlet temperature is <260°C, the third thermal management mode is entered.

[0014] In one embodiment of the present invention, the continuous monitoring of whether the SCR inlet temperature is greater than or equal to the first calibration value specifically means that the ECU continuously monitors whether the SCR inlet temperature is greater than or equal to 260°C.

[0015] Secondly, the present invention provides a control system for increasing the exhaust temperature of a diesel engine, comprising: a judgment module, an entry module, a monitoring module, and an exit module. The judgment module is used to initialize temperature conditions and determine whether the engine coolant temperature and the SCR inlet temperature are less than preset values; the entry module is used to enter a thermal management mode if the values ​​are less than the preset values; the monitoring module is used to continuously monitor whether the SCR inlet temperature is greater than or equal to a calibrated value; and the exit module is used to exit the thermal management mode and enter a normal mode if the values ​​are greater than the calibrated value.

[0016] In one embodiment of the present invention, the initial temperature conditions include initializing engine speed, engine circulating oil volume, ambient temperature, ambient pressure, vehicle gear, vehicle speed, and urea injection status.

[0017] In one embodiment of the present invention, determining whether the engine coolant temperature and the SCR inlet temperature are less than preset values ​​specifically involves determining whether the engine coolant temperature is less than 70°C and whether the SCR inlet temperature is less than 210°C.

[0018] In one embodiment of the present invention, the thermal management mode includes a first thermal management mode, a second thermal management mode, and a third thermal management mode.

[0019] Compared with the prior art, the control method and system for increasing the exhaust temperature of diesel engines according to the present invention can increase the temperature quickly and keep the SCR catalyst in a high-efficiency temperature range at all times. Different methods of increasing the exhaust temperature are used under different engine operating conditions, which can reduce NOx emissions while having less additional fuel consumption. At the same time, it is universal and can be applied to all platform diesel engines of this type of configuration. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating a method for controlling the exhaust temperature of a diesel engine according to an embodiment of the present invention.

[0021] Figure 2 This is a schematic diagram of the logic flow of a control method for increasing the exhaust temperature of a diesel engine according to an embodiment of the present invention;

[0022] Figure 3 This is a schematic diagram of the structure of a control system for increasing the exhaust temperature of a diesel engine according to an embodiment of the present invention;

[0023] Figure 4 This is a schematic diagram of a control system for increasing the exhaust temperature of a diesel engine according to a specific embodiment of the present invention. Detailed Implementation

[0024] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0025] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0026] The existing aftertreatment temperature control strategy involves detecting the engine's ambient temperature, ambient pressure, DOC inlet temperature, DPF inlet temperature, engine circulating oil volume, engine speed, fuel tank volume, torque fault status, engine temperature, and engine operating mode. Once all these conditions meet the set requirements, the engine's operating mode switches from normal mode to aftertreatment temperature boosting mode, and the engine's combustion parameters are adjusted (rail pressure, near-after injection quantity, near-after injection angle, injection advance angle, throttle, EGR opening, etc.).

[0027] Figure 4 This is a schematic diagram of a control system for increasing the exhaust temperature of a diesel engine according to a specific embodiment of the present invention, as shown below. Figure 4As shown, in order to further increase the exhaust temperature, an EHC (electric heating) is added to the front end of the catalytic converter based on the original aftertreatment scheme. The ECU controls it and adjusts the combustion state of the engine and the working state of the EHC in combination with the SCR inlet temperature, so that the exhaust temperature is in the high-efficiency range of SCR conversion efficiency, achieving ultra-low NOx emissions and reducing air pollution.

[0028] Figure 1 This is a flowchart illustrating a method for controlling the exhaust temperature of a diesel engine according to an embodiment of the present invention, as shown below. Figure 1 As shown, in a first aspect, a control method for increasing the exhaust temperature of a diesel engine according to a preferred embodiment of the present invention includes: step S100, initializing temperature conditions and determining whether the engine coolant temperature and SCR inlet temperature are less than preset values; step S200, if less than the preset values, entering a thermal management mode; step S300, continuously monitoring whether the SCR inlet temperature is greater than or equal to a calibration value; step S400, if greater than the calibration value, exiting the thermal management mode and entering a normal mode.

[0029] In one embodiment of the present invention, the initial temperature conditions include initializing engine speed, engine circulating oil volume, ambient temperature, ambient pressure, vehicle gear, vehicle speed, and urea injection status.

[0030] In one embodiment of the present invention, determining whether the engine coolant temperature and the SCR inlet temperature are less than preset values ​​specifically involves determining whether the engine coolant temperature is less than 70°C and whether the SCR inlet temperature is less than 210°C.

[0031] In one embodiment of the present invention, the thermal management mode includes a first thermal management mode, a second thermal management mode, and a third thermal management mode.

[0032] In one embodiment of the present invention, step S200 includes:

[0033] If it is less than the preset value, enter the first thermal management mode or the third thermal management mode;

[0034] In the first thermal management mode, if the engine coolant temperature is ≥70℃ and 260℃ ≥ SCR inlet temperature ≥210℃, the second thermal management mode is entered.

[0035] In the second thermal management mode, if the engine coolant temperature is ≥70℃ and the SCR inlet temperature is <210℃, the first thermal management mode is entered.

[0036] In the first thermal management mode or the second thermal management mode, if the engine coolant temperature is <70°C and the SCR inlet temperature is <260°C, the third thermal management mode is entered.

[0037] In one embodiment of the present invention, the continuous monitoring of whether the SCR inlet temperature is greater than or equal to the first calibration value specifically means that the ECU continuously monitors whether the SCR inlet temperature is greater than or equal to 260°C.

[0038] Figure 3 This is a schematic diagram of a control system for increasing the exhaust temperature of a diesel engine according to an embodiment of the present invention, as shown below. Figure 3 As shown, in a second aspect, the present invention provides a control system for increasing the exhaust temperature of a diesel engine, comprising: a judgment module 301, an entry module 302, a monitoring module 303, and an exit module 304. The judgment module 301 is used to initialize temperature conditions and determine whether the engine coolant temperature and the SCR inlet temperature are less than preset values; the entry module 302 is used to enter a thermal management mode if the values ​​are less than the preset values; the monitoring module 303 is used to continuously monitor whether the SCR inlet temperature is greater than or equal to a calibrated value; and the exit module 304 is used to exit the thermal management mode and enter a normal mode if the values ​​are greater than the calibrated value.

[0039] In one embodiment of the present invention, the initial temperature conditions include initializing engine speed, engine circulating oil volume, ambient temperature, ambient pressure, vehicle gear, vehicle speed, and urea injection status.

[0040] In one embodiment of the present invention, determining whether the engine coolant temperature and the SCR inlet temperature are less than preset values ​​specifically involves determining whether the engine coolant temperature is less than 70°C and whether the SCR inlet temperature is less than 210°C.

[0041] In one embodiment of the present invention, the thermal management mode includes a first thermal management mode, a second thermal management mode, and a third thermal management mode.

[0042] Currently, internal combustion engines face the dual pressures of emissions and fuel consumption, with emissions and fuel consumption showing a trend of inverse relationship. Therefore, while ensuring that emissions meet regulatory requirements, we should minimize the use of thermal management control to keep fuel consumption at a relatively optimal level.

[0043] The present invention aims to increase exhaust temperature with lower fuel consumption. By segmenting the SCR inlet temperature and using different methods to increase exhaust temperature, the SCR catalyst is always in a highly efficient state, achieving ultra-low NOx emissions.

[0044] In practical applications, such as Figure 2As shown, this invention enters the EHC thermal management mode (first thermal management mode) to raise the temperature of the SCR catalyst when the engine coolant temperature monitored by the ECU is <70℃ and T6 is <210℃, and the engine speed, engine oil circulation volume, ambient temperature, ambient pressure, urea injection status and other conditions are all met. When the engine coolant temperature is ≥70℃ and 260℃≥T6≥210℃, and the engine speed, engine oil circulation volume, ambient temperature, ambient pressure, urea temperature, urea injection status, battery voltage, exhaust flow and other conditions are all met, it simultaneously enters the RHU thermal management mode (second thermal management mode) to circulate and raise the temperature of the catalyst, thereby reducing NOx emissions.

[0045] When the engine coolant temperature monitored by the ECU is ≥70℃, and the detected T6 is ≥210℃, and the engine speed, engine oil circulation volume, ambient temperature, ambient pressure, and urea injection status all meet the conditions, the system enters the RHU thermal management mode (second thermal management mode). When the engine coolant temperature monitored by the ECU is ≥70℃, and the detected T6 is <210℃, and the engine speed, engine oil circulation volume, ambient temperature, ambient pressure, and urea injection status all meet the conditions, the system enters the EHC thermal management mode (first thermal management mode) to raise the temperature of the SCR catalyst.

[0046] When the engine coolant temperature is <70℃ and T6 is <260℃, the engine speed, engine oil circulation volume, ambient temperature, ambient pressure, urea injection status, urea temperature, battery voltage, and exhaust flow rate are all satisfied, and the system enters the EHC thermal management mode (third thermal management mode) to keep the SCR catalyst warm.

[0047] The ECU detects that when T6 ≥ 260℃, it exits the EHC thermal management and RHU thermal management modes. In the EHC thermal management mode, the ECU heats the exhaust gas by controlling the electric heating when the demand for exhaust temperature heating is reached. In the RHU thermal management mode, the ECU adjusts the engine's combustion control parameters (rail pressure, injection advance angle, throttle body, and after-injection) when the demand for exhaust temperature heating is reached.

[0048] In summary, the method and system for controlling the exhaust temperature of diesel engines of the present invention can rapidly increase the temperature while ensuring that the SCR catalyst is always in a highly efficient temperature range. Different methods for increasing the exhaust temperature are used under different engine operating conditions, which reduces NOx emissions while minimizing additional fuel consumption. Furthermore, it is universally applicable to all platform diesel engines of this configuration.

[0049] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A method for controlling the exhaust temperature of a diesel engine, characterized in that, include: Step S100: Initialize temperature conditions and determine whether the engine coolant temperature and SCR inlet temperature are lower than preset values; Step S200: If it is less than the preset value, then: When the engine coolant temperature is lower than the first coolant temperature threshold, the engine enters the first thermal management mode. When the engine coolant temperature is greater than or equal to the first coolant temperature threshold and the SCR inlet temperature is less than the first SCR temperature threshold, the first thermal management mode is entered. When the engine coolant temperature is greater than or equal to the first coolant temperature threshold and the SCR inlet temperature is greater than or equal to the first SCR temperature threshold and less than the second SCR temperature threshold, the second thermal management mode is entered. In the first thermal management mode, the exhaust gas is heated by an electric heater, and in the second thermal management mode, the exhaust gas is heated by adjusting the engine's combustion control parameters. Step S300: Continuously monitor whether the SCR inlet temperature is greater than or equal to the calibration value; Step S400: If the value is greater than the calibration value, exit the thermal management mode and enter the normal mode.

2. The control method for increasing the exhaust temperature of a diesel engine as described in claim 1, characterized in that, The initialization temperature conditions include initializing engine speed, engine oil circulation volume, ambient temperature, ambient pressure, vehicle gear, vehicle speed, and urea injection status.

3. The control method for increasing the exhaust temperature of a diesel engine as described in claim 1, characterized in that, The specific steps for determining whether the engine coolant temperature and SCR inlet temperature are less than preset values ​​are as follows: Determine whether the engine coolant temperature is less than 70°C and whether the SCR inlet temperature is less than 210°C.

4. The control method for increasing the exhaust temperature of a diesel engine as described in claim 3, characterized in that, The continuous monitoring of whether the SCR inlet temperature is greater than or equal to the first calibration value specifically means that the ECU continuously monitors whether the SCR inlet temperature is greater than or equal to 260°C.

5. A control system for increasing the exhaust temperature of a diesel engine, based on the control method for increasing the exhaust temperature of a diesel engine as described in any one of claims 1 to 4, characterized in that, The system includes: The judgment module is used to initialize temperature conditions and determine whether the engine coolant temperature and SCR inlet temperature are lower than preset values. The module is used to enter thermal management mode if the value is less than a preset value. The monitoring module is used to continuously monitor whether the SCR inlet temperature is greater than or equal to the calibration value; and The exit module is used to exit the thermal management mode and enter the normal mode if the value is greater than the calibration value.

6. The control system for increasing diesel engine exhaust temperature as described in claim 5, characterized in that, The initialization temperature conditions include initializing engine speed, engine oil circulation volume, ambient temperature, ambient pressure, vehicle gear, vehicle speed, and urea injection status.

7. The control system for increasing diesel engine exhaust temperature as described in claim 5, characterized in that, The specific steps for determining whether the engine coolant temperature and SCR inlet temperature are less than preset values ​​are as follows: Determine whether the engine coolant temperature is less than 70°C and whether the SCR inlet temperature is less than 210°C.

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