EGR control method, vehicle-mounted terminal and vehicle

Abstract

The invention relates to an EGR control method, a vehicle-mounted terminal and a vehicle. The method comprises the steps that the vehicle is powered on, and whether EGR enabling conditions are met or not is judged; if yes, the opening degree of an EGR valve is controlled according to the first calibration data, and the cooling liquid flow of an EGR cooler is controlled according to the second calibration data; if not, the EGR valve is kept closed; when the EGR enabling condition is met, a first difference value between the gas outlet temperature of an EGR cooler under the current engine working condition and the target EGR gas temperature corresponding to the working condition in third calibration data is calculated; and if the first difference value is larger than 0, the cooling liquid flow of the EGR cooler is increased till the first difference value falls into the first temperature difference range. According to the EGR control method, generation of condensate water in the EGR valve can be reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of EGR, and in particular relates to an EGR control method, a vehicle-mounted terminal and a vehicle. Background Art

[0002] EGR (Exhaust Gas Re-circulation) refers to sending part of the exhaust gas (EGR gas) discharged by the engine back to the intake manifold and re-entering the cylinder together with the fresh mixed gas. The EGR valve is the core component of the EGR system, which is used to adjust the flow of EGR gas entering the intake manifold of the engine. When the temperature of the high-temperature EGR gas drops below the dew point temperature, condensed water will precipitate from the EGR gas. If the production of condensed water is not controlled, it may cause the engine to stall or corrode the EGR valve in severe cases.

[0003] At present, the common practice on the market to reduce the generation of condensed water is to use the engine's own high-temperature cooling water to cool the EGR gas through the EGR cooler, so that the outlet temperature of the EGR cooler is controlled above 57°C (dew point temperature) to avoid the generation of condensed water and reduce the corrosion of the EGR valve by condensed water. Although this method can reduce the generation of condensed water to a certain extent, it sacrifices the thermal efficiency of the engine to a great extent.

[0004] However, with the development of hybrid vehicles, when the vehicle is at low speed, usually only the motor is working, and the engine is intermittent. It is difficult for the engine water temperature to be stabilized above 60°C for a long time, and the outlet temperature of the EGR cooler is also difficult to control above the dew point temperature. Especially for the cooling scheme that uses a medium-temperature cooling system to cool the EGR gas, the outlet temperature of the EGR cooler is usually below the dew point temperature, and the generation of condensed water in the housing of the EGR valve is inevitable.

[0005] Therefore, it is necessary to reduce the generation of condensed water in the EGR valve. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide an EGR control method, a vehicle-mounted terminal and a vehicle to reduce the generation of condensed water in the EGR valve.

[0007] In order to solve the above problems, on the one hand, an embodiment of the present invention provides an EGR control method, including:

[0008] The vehicle is powered on to determine whether the EGR enabling conditions are met;

[0009] If yes, the opening of the EGR valve is controlled according to the first calibration data, and the coolant flow of the EGR cooler is controlled according to the second calibration data; if no, the EGR valve is kept closed;

[0010] When the EGR enabling condition is met, calculating a first difference between an EGR cooler outlet gas temperature under the current engine operating condition and a target EGR gas temperature corresponding to the operating condition in the third calibration data;

[0011] If the first difference is greater than 0, increasing the coolant flow of the EGR cooler until the first difference falls within a first temperature difference range;

[0012] If the first difference value still does not fall within the first temperature difference range when the coolant flow rate of the EGR cooler increases to the maximum, the maximum coolant flow rate of the EGR cooler is maintained for a preset time;

[0013] If the EGR cooler outlet temperature is greater than the calibrated maximum temperature after the preset time, the opening of the EGR valve is reduced.

[0014] According to the EGR control method of the embodiment of the present invention, the opening of the EGR valve is controlled according to the first calibration data, and the coolant flow of the EGR cooler is controlled according to the second calibration data. When the EGR enabling condition is met, the first difference between the outlet temperature of the EGR cooler under the current engine working condition and the target EGR gas temperature corresponding to the working condition in the third calibration data is calculated; when the first difference is greater than 0, the coolant flow of the EGR cooler is increased until the first difference falls within the first temperature difference range. In this way, the outlet temperature of the EGR cooler under the current engine working condition is close to the target EGR gas temperature corresponding to the working condition in the third calibration data. When the third calibration data is bench calibrated, the amount of condensed water generated can be controlled at the target EGR gas temperature through in-cylinder combustion analysis, thereby reducing the generation of condensed water in the EGR valve when the vehicle is actually driving. Compared with the prior art, the EGR control method of the embodiment of the present invention can reduce the amount of condensed water generated from 10L / min in the prior art to 1L / min.

[0015] In addition, if the first difference value still does not fall within the first temperature difference range when the coolant flow rate of the EGR cooler increases to the maximum, the maximum coolant flow rate of the EGR cooler is maintained for a preset time; if the outlet temperature of the EGR cooler is greater than the calibrated maximum temperature after the preset time, the opening of the EGR valve is reduced. In this way, the EGR valve overheating is avoided by reducing the opening of the EGR valve, and the combustion in the engine cylinder is prevented from deteriorating.

[0016] Optionally, if the first difference is greater than 0, and increasing the coolant flow of the EGR cooler does not reach the maximum coolant flow, and the first difference falls within the first temperature difference range, the coolant flow of the EGR cooler is controlled according to the second calibration data.

[0017] Optionally, if after the preset time, the EGR cooler outlet temperature is less than or equal to the calibrated maximum temperature, the current opening of the EGR valve is maintained.

[0018] Optionally, the preset time is greater than or equal to 10s;

[0019] and / or,

[0020] The maximum calibrated temperature is 60-80°C;

[0021] and / or,

[0022] The first temperature difference range is -3-3°C.

[0023] Optionally, if the first difference is less than or equal to 0, reducing the coolant flow of the EGR cooler until the first difference falls within the first temperature difference range;

[0024] If the coolant flow of the EGR cooler is reduced to the minimum, and the EGR cooler outlet temperature under the current engine operating condition has not risen to the target EGR gas temperature corresponding to the operating condition in the third calibration data minus the tolerance value, the minimum coolant flow of the EGR cooler is maintained.

[0025] Optionally, the tolerance value is 1-3°C.

[0026] Optionally, if the first difference is less than or equal to 0, and reducing the coolant flow of the EGR cooler does not reach the minimum coolant flow, and the first difference falls within the first temperature difference range, the coolant flow of the EGR cooler is controlled according to the second calibration data.

[0027] Optionally, before the vehicle is powered on and whether the EGR enabling condition is met, the following steps are further included:

[0028] Before the vehicle is powered on, keep the EGR valve closed;

[0029] Check whether the engine water temperature sensor, medium temperature cooling system water temperature sensor, ambient temperature sensor, engine intake air temperature sensor and vehicle speed sensor are faulty;

[0030] If at least one of the engine water temperature sensor, the medium temperature cooling system water temperature sensor, the ambient temperature sensor, the engine intake air temperature sensor and the vehicle speed sensor fails, the EGR valve is kept closed;

[0031] If the engine water temperature sensor, the medium temperature cooling system water temperature sensor, the ambient temperature sensor, the engine intake air temperature sensor and the vehicle speed sensor are all detected normally, then the engine water temperature detected by the engine water temperature sensor, the medium temperature cooling system water temperature detected by the medium temperature cooling system water temperature sensor, the vehicle's surrounding ambient temperature detected by the ambient temperature sensor, the engine intake air temperature detected by the engine intake air temperature sensor and the vehicle speed detected by the vehicle speed sensor are read.

[0032] Optionally, the EGR enabling conditions include:

[0033] a. The engine intake temperature is greater than or equal to the first lower temperature limit;

[0034] b. The vehicle's surrounding temperature is greater than or equal to the second lower temperature limit;

[0035] c. The vehicle speed is greater than or equal to the preset speed;

[0036] d. The engine running time exceeds the warm-up time;

[0037] e. The engine water temperature sensor, medium temperature cooling system water temperature sensor, ambient temperature sensor, engine intake air temperature sensor and vehicle speed sensor are all tested normal.

[0038] Optionally, the first lower limit temperature is 1-3°C;

[0039] and / or,

[0040] The second lower temperature limit is 1-3°C;

[0041] and / or,

[0042] The preset vehicle speed is 20km / h;

[0043] and / or,

[0044] The warm-up time is 250-350s.

[0045] Optionally,

[0046] When the vehicle is powered on, the following steps are also included before determining whether the EGR enabling conditions are met:

[0047] Acquiring the first calibration data, the second calibration data and the third calibration data through an engine bench test;

[0048] The first calibration data indicates the target EGR gas temperature required under different engine speeds and different engine cylinder mean effective pressures measured when the engine is burning normally, taking the lowest engine fuel consumption as the benchmark;

[0049] The second calibration data indicates the target coolant flow rate of the EGR cooler required under different engine speeds and different engine cylinder mean effective pressures measured when the engine is burning normally, with the lowest engine fuel consumption as the benchmark;

[0050] The third calibration data indicates the target EGR valve opening required under different engine speeds and different engine cylinder mean effective pressures measured when the engine is burning normally, taking the lowest engine fuel consumption as a benchmark.

[0051] Optionally, if after the preset time, the EGR cooler outlet temperature is greater than a calibrated maximum temperature, reducing the opening of the EGR valve includes:

[0052] If the EGR cooler outlet temperature is greater than the calibrated maximum temperature after the preset time, the opening of the EGR valve is controlled according to the fourth calibration data.

[0053] Optionally, the fourth calibration data is obtained through an engine bench test;

[0054] The fourth calibration data indicates the target EGR valve opening required under different engine speeds and different EGR gas temperatures measured when the engine is burning normally, taking the lowest engine fuel consumption as a benchmark.

[0055] On the other hand, an embodiment of the present invention provides a vehicle-mounted terminal, including a memory and a processor, wherein the memory stores a computer program;

[0056] The processor is used to execute the computer program to implement the above-mentioned EGR control method.

[0057] On the other hand, an embodiment of the present invention provides a vehicle, including the above-mentioned vehicle-mounted terminal. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 It is a flow chart of an EGR control method provided by an embodiment of the present invention;

[0059] Figure 2 is a schematic diagram of first calibration data of an EGR control method provided by an embodiment of the present invention;

[0060] Figure 3 This is the intention of the second calibration data of the EGR control method provided by one embodiment of the present invention;

[0061] Figure 4 This is the intention of the third calibration data of the EGR control method provided by one embodiment of the present invention;

[0062] Figure 5 This is the intention of the fourth calibration data of the EGR control method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0063] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0064] like Figure 1 As shown, an embodiment of the present invention provides an EGR control method, comprising:

[0065] The vehicle is powered on to determine whether the EGR enabling conditions are met;

[0066] If yes, the opening of the EGR valve is controlled according to the first calibration data, and the coolant flow of the EGR cooler is controlled according to the second calibration data; if no, the EGR valve is kept closed;

[0067] When the EGR enabling condition is met, calculating a first difference between an EGR cooler outlet gas temperature under the current engine operating condition and a target EGR gas temperature corresponding to the operating condition in the third calibration data;

[0068] If the first difference is greater than 0, increasing the coolant flow of the EGR cooler until the first difference falls within a first temperature difference range;

[0069] If the first difference value still does not fall within the first temperature difference range when the coolant flow rate of the EGR cooler increases to the maximum, the maximum coolant flow rate of the EGR cooler is maintained for a preset time;

[0070] If the EGR cooler outlet temperature is greater than the calibrated maximum temperature after the preset time, the opening of the EGR valve is reduced.

[0071] According to the EGR control method of the embodiment of the present invention, the opening of the EGR valve is controlled according to the first calibration data, and the coolant flow of the EGR cooler is controlled according to the second calibration data. When the EGR enabling condition is met, the first difference between the outlet temperature of the EGR cooler under the current engine working condition and the target EGR gas temperature corresponding to the working condition in the third calibration data is calculated; when the first difference is greater than 0, the coolant flow of the EGR cooler is increased until the first difference falls within the first temperature difference range. In this way, the outlet temperature of the EGR cooler under the current engine working condition is close to the target EGR gas temperature corresponding to the working condition in the third calibration data. When the third calibration data is bench calibrated, the amount of condensed water generated can be controlled at the target EGR gas temperature through in-cylinder combustion analysis, thereby reducing the generation of condensed water in the EGR valve when the vehicle is actually driving. Compared with the prior art, the EGR control method of the embodiment of the present invention can reduce the amount of condensed water generated from 10L / min in the prior art to 1L / min.

[0072] In addition, if the first difference value still does not fall within the first temperature difference range when the coolant flow rate of the EGR cooler increases to the maximum, the maximum coolant flow rate of the EGR cooler is maintained for a preset time; if the outlet temperature of the EGR cooler is greater than the calibrated maximum temperature after the preset time, the opening of the EGR valve is reduced. In this way, the EGR valve overheating is avoided by reducing the opening of the EGR valve, and the combustion in the engine cylinder is prevented from deteriorating.

[0073] This method can be used for the cooling scheme of cooling EGR gas in the medium temperature cooling system. The medium temperature cooling system is usually equipped with an EGR cooler, an intercooler, an EGR valve, a water pump, and a heat exchanger. The water pump, the heat exchanger, and the intercooler form a coolant loop. The water circuit of the EGR cooler is connected in series in the above-mentioned coolant loop. The inlet of the gas flow channel of the EGR valve is connected to the gas outlet of the EGR cooler. The coolant flowing out of the water pump enters the water circuit of the EGR cooler through the heat exchanger and the intercooler to cool the high temperature gas (usually 500-600°C) in the EGR cooler. The cooled gas then enters the EGR valve, and the outlet of the EGR valve is connected to the intake system of the engine.

[0074] The EGR gas is cooled by a low-temperature intermediate-temperature cooling system to obtain EGR gas at a lower temperature, which is beneficial to improving combustion and increasing the thermal efficiency of the engine.

[0075] In one embodiment, if the first difference is greater than 0, and increasing the coolant flow of the EGR cooler does not reach the maximum coolant flow, and the first difference falls within the first temperature difference range, the coolant flow of the EGR cooler is controlled according to the second calibration data.

[0076] In one embodiment, if the EGR cooler outlet temperature is less than or equal to the calibrated maximum temperature after the preset time, the current opening of the EGR valve is maintained. If the EGR cooler outlet temperature is less than or equal to the calibrated maximum temperature, it indicates that the EGR valve over-humidification phenomenon does not exist, and maintaining the current opening of the EGR valve is conducive to improving fuel economy.

[0077] In one embodiment, the preset time is greater than or equal to 10s, so that there is enough time to make a judgment and avoid reducing the opening of the EGR valve too early; the calibrated maximum temperature is 60-80°C, and the calibrated maximum temperature is above the condensation temperature of the EGR gas; the first temperature difference range is -3-3°C, so that the EGR cooler outlet temperature under the current engine operating condition is as close as possible to the target EGR gas temperature corresponding to the operating condition in the third calibration data.

[0078] In one embodiment, if the first difference is less than or equal to 0, the coolant flow of the EGR cooler is reduced until the first difference falls within the first temperature difference range; if the coolant flow of the EGR cooler is reduced to a minimum, and the outlet temperature of the EGR cooler under the current engine operating condition has not risen to a level corresponding to the target EGR gas temperature corresponding to the operating condition in the third calibration data minus the tolerance value, the minimum coolant flow of the EGR cooler is maintained.

[0079] In one embodiment, the tolerance value is 1-3° C., so that the EGR cooler outlet gas temperature under the current engine operating condition is as close as possible to the target EGR gas temperature corresponding to the operating condition in the third calibration data.

[0080] In one embodiment, if the first difference is less than or equal to 0, and reducing the coolant flow of the EGR cooler does not reach the minimum coolant flow, and the first difference falls within the first temperature difference range, the coolant flow of the EGR cooler is controlled according to the second calibration data.

[0081] In one embodiment, before the vehicle is powered on and whether the EGR enabling condition is met, the following step is further performed:

[0082] Before the vehicle is powered on, keep the EGR valve closed. Before the vehicle is powered on, the EGR valve is closed by default to prevent a large amount of engine exhaust gas from entering the cylinder at the moment of engine startup, causing the engine to misfire (stall).

[0083] Check whether the engine water temperature sensor, medium temperature cooling system water temperature sensor, ambient temperature sensor, engine intake air temperature sensor and vehicle speed sensor are faulty. The engine water temperature sensor is arranged on the cylinder block of the engine and is used to detect the water outlet temperature of the engine's water jacket. The medium temperature cooling system water temperature sensor is arranged in the above-mentioned coolant circuit. The engine intake air temperature sensor is arranged in the engine's intake system, usually before the air filter. The vehicle speed sensor is usually a wheel speed sensor, which is arranged on the drive shaft or on the wheel, and converts the wheel speed into vehicle speed. The ambient temperature sensor is arranged on the vehicle body and is used to detect the temperature of the environment in which the vehicle is located.

[0084] If at least one of the engine water temperature sensor, the medium temperature cooling system water temperature sensor, the ambient temperature sensor, the engine intake air temperature sensor and the vehicle speed sensor fails, the EGR valve is kept closed. At the same time, an alarm can also be issued when at least one of the engine water temperature sensor, the medium temperature cooling system water temperature sensor, the ambient temperature sensor, the engine intake air temperature sensor and the vehicle speed sensor fails.

[0085] If the engine water temperature sensor, the medium temperature cooling system water temperature sensor, the ambient temperature sensor, the engine intake air temperature sensor and the vehicle speed sensor are all detected normally, then the engine water temperature detected by the engine water temperature sensor, the medium temperature cooling system water temperature detected by the medium temperature cooling system water temperature sensor, the vehicle's surrounding ambient temperature detected by the ambient temperature sensor, the engine intake air temperature detected by the engine intake air temperature sensor and the vehicle speed detected by the vehicle speed sensor are read.

[0086] In one embodiment, the EGR enabling conditions include:

[0087] a. The engine intake temperature is greater than or equal to the first lower limit temperature; b. The vehicle's surrounding ambient temperature is greater than or equal to the second lower limit temperature; c. The vehicle speed is greater than or equal to the preset speed; d. The engine running time exceeds the warm-up time; e. The engine water temperature sensor, medium temperature cooling system water temperature sensor, ambient temperature sensor, engine intake temperature sensor and vehicle speed sensor are all tested normal.

[0088] In one embodiment, the first lower limit temperature is 1-3°C, for example, 3°C; the second lower limit temperature is 1-3°C, for example, 3°C; the preset vehicle speed is 20km / h; and the warm-up time is 250-350s, for example, 250s or 350s.

[0089] In one embodiment, when the vehicle is powered on, before determining whether the EGR enabling condition is met, the following step is further included:

[0090] The first calibration data, the second calibration data and the third calibration data are obtained through engine bench tests. The inlet water temperature of the EGR cooler used in the engine bench calibration is determined with reference to the common water temperature of the vehicle WLTC operating condition (for example, the inlet water temperature of the EGR cooler can be 45°C, and this value can be adjusted according to actual conditions). By adjusting the inlet water flow of the EGR cooler to obtain different EGR cooler outlet temperatures, when the engine does not have abnormal combustion such as pre-ignition, detonation and condensation misfire (that is, the engine is burning normally), the EGR cooler outlet temperature when the engine fuel consumption is the lowest is used as the calibrated target EGR gas temperature, thereby obtaining the basic EGR gas temperature MAP ( Figure 4 The third calibration data shown), the coolant flow MAP of the basic EGR cooler (such as Figure 3 The second calibration data shown) and the basic EGR valve opening MAP ( Figure 2 The first calibration data shown).

[0091] like Figure 2 As shown, the first calibration data indicates the target EGR valve opening required under different engine speeds and different engine cylinder mean effective pressures (BMEP) measured when the engine is burning normally, taking the lowest engine fuel consumption as the benchmark. The unit of the engine cylinder mean effective pressure is MPa, and the unit of the engine speed is rpm.

[0092] like Figure 3 As shown, the second calibration data indicates that when the engine is burning normally, the target coolant flow rate of the EGR cooler required under different engine speeds and different engine cylinder mean effective pressures measured, with the lowest engine fuel consumption as the benchmark. The unit of the coolant flow rate is L / min.

[0093] like Figure 4 As shown, the third calibration data represents the target EGR gas temperature required under different engine speeds and different engine cylinder mean effective pressures measured when the engine is burning normally, taking the lowest engine fuel consumption as a benchmark.

[0094] In one embodiment, if after the preset time, the EGR cooler outlet temperature is greater than the calibrated maximum temperature, reducing the opening of the EGR valve includes:

[0095] If the EGR cooler outlet temperature is greater than the calibrated maximum temperature after the preset time, the opening of the EGR valve is controlled according to the fourth calibration data.

[0096] In one embodiment,

[0097] like Figure 5As shown, the fourth calibration data indicates that when the engine is burning normally, based on the lowest engine fuel consumption, the target EGR valve opening required under different engine speeds (horizontal axis) and different EGR gas temperatures (vertical axis) measured. The EGR valve opening is the ratio of the flow area of ​​the gas channel of the EGR valve to the cross-sectional area of ​​the gas channel. For example, an opening of 0 indicates that the flow area of ​​the gas channel of the EGR valve is 0, that is, the valve plate in the gas channel of the EGR valve is completely closed at this time; an opening of 60 indicates that the ratio of the flow area of ​​the gas channel of the EGR valve to the cross-sectional area of ​​the gas channel is 60%, and the valve plate in the gas channel of the EGR valve is rotated to a certain angle. On the other hand, an embodiment of the present invention provides a vehicle-mounted terminal, including a memory and a processor, wherein the memory stores a computer program;

[0098] The processor is used to execute the computer program to implement the above-mentioned EGR control method.

[0099] On the other hand, an embodiment of the present invention provides a vehicle, including the above-mentioned vehicle-mounted terminal.

[0100] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An EGR control method, characterized in that: include: The vehicle is powered on to determine whether the EGR enabling conditions are met; If so, controlling the opening of the EGR valve according to the first calibration data, and controlling the coolant flow of the EGR cooler according to the second calibration data; If not, keep the EGR valve closed; When the EGR enabling condition is met, calculating a first difference between an EGR cooler outlet gas temperature under the current engine operating condition and a target EGR gas temperature corresponding to the operating condition in the third calibration data; If the first difference is greater than 0, increasing the coolant flow of the EGR cooler until the first difference falls within a first temperature difference range; If the first difference value still does not fall within the first temperature difference range when the coolant flow rate of the EGR cooler increases to the maximum, the maximum coolant flow rate of the EGR cooler is maintained for a preset time; If the EGR cooler outlet temperature is greater than the calibrated maximum temperature after the preset time, the opening of the EGR valve is reduced.

2. The EGR control method according to claim 1, characterized in that: If the first difference is greater than 0, and increasing the coolant flow of the EGR cooler does not reach the maximum coolant flow, and the first difference falls within the first temperature difference range, the coolant flow of the EGR cooler is controlled according to the second calibration data.

3. The EGR control method according to claim 1, characterized in that: If the EGR cooler outlet temperature is less than or equal to the calibrated maximum temperature after the preset time, the current opening of the EGR valve is maintained.

4. The EGR control method according to claim 1, characterized in that: The preset time is greater than or equal to 10s; and / or, The maximum calibrated temperature is 60-80°C; and / or, The first temperature difference range is -3-3°C.

5. The EGR control method according to claim 1, characterized in that: If the first difference is less than or equal to 0, reducing the coolant flow of the EGR cooler until the first difference falls within the first temperature difference range; If the coolant flow of the EGR cooler is reduced to the minimum, and the EGR cooler outlet temperature under the current engine operating condition has not risen to the target EGR gas temperature corresponding to the operating condition in the third calibration data minus the tolerance value, the minimum coolant flow of the EGR cooler is maintained.

6. The EGR control method according to claim 5, characterized in that: The tolerance value is 1-3°C.

7. The EGR control method according to claim 6, characterized in that: If the first difference is less than or equal to 0, and reducing the coolant flow of the EGR cooler does not reach the minimum coolant flow, and the first difference falls within the first temperature difference range, the coolant flow of the EGR cooler is controlled according to the second calibration data.

8. The EGR control method according to claim 1, characterized in that: When the vehicle is powered on, before determining whether the EGR enabling conditions are met, the following steps are also required: Before the vehicle is powered on, keep the EGR valve closed; Check whether the engine water temperature sensor, medium temperature cooling system water temperature sensor, ambient temperature sensor, engine intake air temperature sensor and vehicle speed sensor are faulty; If at least one of the engine water temperature sensor, the medium temperature cooling system water temperature sensor, the ambient temperature sensor, the engine intake air temperature sensor and the vehicle speed sensor fails, the EGR valve is kept closed; If the engine water temperature sensor, the medium temperature cooling system water temperature sensor, the ambient temperature sensor, the engine intake air temperature sensor and the vehicle speed sensor are all detected normally, then the engine water temperature detected by the engine water temperature sensor, the medium temperature cooling system water temperature detected by the medium temperature cooling system water temperature sensor, the vehicle's surrounding ambient temperature detected by the ambient temperature sensor, the engine intake air temperature detected by the engine intake air temperature sensor and the vehicle speed detected by the vehicle speed sensor are read.

9. The EGR control method according to claim 8, characterized in that: EGR enabling conditions include: a. The engine intake temperature is greater than or equal to the first lower temperature limit; b. The vehicle's surrounding temperature is greater than or equal to the second lower temperature limit; c. The vehicle speed is greater than or equal to the preset speed; d. The engine running time exceeds the warm-up time; e. The engine water temperature sensor, medium temperature cooling system water temperature sensor, ambient temperature sensor, engine intake air temperature sensor and vehicle speed sensor are all tested normal.

10. The EGR control method according to claim 9, characterized in that: The first lower limit temperature is 1-3°C; and / or, The second lower temperature limit is 1-3°C; and / or, The preset vehicle speed is 20km / h; and / or, The warm-up time is 250-350s.

11. The EGR control method according to claim 10, characterized in that: When the vehicle is powered on, the following steps are also included before determining whether the EGR enabling conditions are met: Acquiring the first calibration data, the second calibration data and the third calibration data through an engine bench test; The first calibration data indicates the target EGR valve opening required under different engine speeds and different engine cylinder mean effective pressures measured when the engine is burning normally, taking the lowest engine fuel consumption as a benchmark; The second calibration data indicates the target coolant flow rate of the EGR cooler required under different engine speeds and different engine cylinder mean effective pressures measured when the engine is burning normally, with the lowest engine fuel consumption as the benchmark; The third calibration data indicates the target EGR gas temperature required under different engine speeds and different engine cylinder mean effective pressures measured when the engine is burning normally, based on the lowest engine fuel consumption.

12. The EGR control method according to any one of claims 1 to 11, characterized in that: If the EGR cooler outlet temperature is greater than the calibrated maximum temperature after the preset time, reducing the opening of the EGR valve includes: If the EGR cooler outlet temperature is greater than the calibrated maximum temperature after the preset time, the opening of the EGR valve is controlled according to the fourth calibration data.

13. The EGR control method according to claim 12, characterized in that: Acquiring the fourth calibration data through an engine bench test; The fourth calibration data indicates the target EGR valve opening required under different engine speeds and different EGR gas temperatures measured when the engine is burning normally, taking the lowest engine fuel consumption as a benchmark.

14. A vehicle-mounted terminal, characterized in that: comprising a memory and a processor, wherein the memory stores a computer program; The processor is used to execute the computer program to implement the EGR control method described in any one of claims 1-13.

15. A vehicle, characterized in that: Including the vehicle-mounted terminal as claimed in claim 14.

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