Method, device and system for anti-condensation control of an engine

Abstract

The application discloses a method, device and system for preventing condensation of an engine. After the engine runs at a first working point for a preset time with a first default EGR rate, the opening of an EGR valve is controlled to reduce the EGR rate within a preset range. A heat dissipation controller in an intercooler is then controlled to increase the intake air temperature of the engine after the intercooler to a first preset temperature and increase the EGR rate to the first default EGR rate. By automatically adjusting the EGR rate and the intake air temperature through the EGR valve and the heat dissipation controller, the condensation of water vapor in the pressurized gas on the intake air system after the intercooler can be effectively prevented. When the engine switches from the first working point with low speed and low load to a second working point with high speed and high load, the opening of the EGR valve is controlled according to the switching speed to prevent the temperature from decreasing too fast to produce condensed water. The misfire problem of the engine during the transient switching process can be solved only by controlling accessories, and the design is reasonable and the method is simple.

Description

Technical Field

[0001] This application relates to the field of exhaust gas recirculation technology, and in particular to a method, device and system for engine anti-condensation control. Background Technology

[0002] Exhaust Gas Recirculation (EGR) technology refers to the process of returning a portion of the exhaust gas from the engine to the intake manifold, where it re-enters the cylinders along with a fresh air-fuel mixture. Exhaust gas contains gases such as CO2, which are non-combustible and have a high specific heat capacity, absorbing a significant amount of heat and lowering the peak combustion temperature of the air-fuel mixture in the cylinders, thereby reducing NOx formation. Structurally, EGR systems can be divided into internal and external EGR systems. Internal EGR systems reduce pumping losses and increase in-cylinder heat load, while external EGR systems connect an exhaust gas recirculation line to the exhaust system, diverting exhaust gas into the intake system to achieve thorough mixing of exhaust gas and fresh air. Based on the intake location before and after the turbocharger's power stroke, external EGR systems are further divided into high-pressure and low-pressure EGR systems. High-pressure EGR systems take in gas before the turbocharger, resulting in higher in-cylinder pressure, while low-pressure EGR systems take in gas after the catalytic converter, expelling some exhaust gas and resulting in lower in-cylinder pressure.

[0003] In existing technologies, most automotive engines employ a low-pressure EGR system and an intercooler. Both the fresh air entering the engine and the EGR gas contain a certain amount of water vapor. After mixing, the fresh air and EGR gas flow through the turbocharger, increasing the temperature and pressure of the mixture. Then, it passes through the intercooler, where its temperature decreases, causing the water vapor in the mixture to condense and form water droplets. As the temperature continues to drop, these water droplets adhere to the walls of the intake system. When the engine transitions from a stable low-speed, low-load condition to a high-speed, high-load acceleration condition, these water droplets can enter the cylinders with the airflow, leading to misfire. Therefore, preventing engine misfire during these operating condition transitions remains a problem that needs further investigation. Summary of the Invention

[0004] In view of the above problems, this application provides a method, device and system for engine anti-condensation control to prevent engine misfire during engine operating condition switching.

[0005] This application discloses a method for engine anti-condensation control, the method comprising:

[0006] After the engine runs at the first default EGR rate for a preset time at the first operating point, the opening of the EGR valve is controlled to reduce the EGR rate within a preset range; the first default EGR rate is the EGR rate selected at the first operating point based on the principle of minimum fuel consumption.

[0007] The heat dissipation controller in the intercooler is controlled to raise the intake air temperature of the engine after the intercooler to a first preset temperature and raise the EGR rate to the first default EGR rate.

[0008] When the engine switches from the first operating point to the second operating point, the opening of the EGR valve is controlled according to the switching speed; the speed of the second operating point is greater than the speed of the first operating point, and the load of the second operating point is greater than the load of the first operating point.

[0009] Optionally, before controlling the opening degree of the EGR valve, the method further includes:

[0010] The preset time is set according to the magnitude of the EGR rate; the preset time ranges from 3 seconds to 180 seconds.

[0011] Optionally, controlling the opening degree of the EGR valve according to the switching speed includes:

[0012] When the switching speed is less than the preset speed, the opening of the EGR valve is reduced;

[0013] When the switching speed is greater than or equal to the preset speed, the EGR valve is closed.

[0014] Optionally, before raising the intake air temperature of the engine after the intercooler to a first preset temperature, the method further includes:

[0015] The dew point temperature of the engine after the intercooler is calculated based on the EGR rate, the proportion of water vapor in the air entering the engine, the proportion of water vapor in the EGR gas entering the engine, and the saturated water vapor pressure in the air-fuel mixture.

[0016] The dew point temperature is increased by a preset dew point temperature to obtain a preset temperature; the preset dew point temperature ranges from 2°C to 6°C.

[0017] Optionally, after the engine switches from the first operating point to the second operating point, the method further includes:

[0018] After the engine runs at the second default EGR rate for a preset time at the second operating point, the opening of the EGR valve is controlled to reduce the EGR rate within a preset range; the second default EGR rate is the EGR rate selected at the second operating point based on the principle of minimum fuel consumption.

[0019] The heat dissipation controller in the intercooler is controlled to raise the intake air temperature of the engine after the intercooler to a second preset temperature and raise the EGR rate to a second default EGR rate.

[0020] Based on the above-mentioned method for engine anti-condensation control, this application also discloses an engine anti-condensation control device, including: a first EGR rate reduction unit, a first EGR rate increase unit, and an EGR valve control unit;

[0021] The first EGR rate reduction unit is used to control the opening of the EGR valve and reduce the EGR rate within a preset range after the engine has been running at the first default EGR rate for a preset time at the first operating point; the first default EGR rate is the EGR rate selected at the first operating point according to the principle of minimum fuel consumption.

[0022] The first EGR rate enhancement unit is used to control the heat dissipation controller in the intercooler to increase the intake air temperature of the engine after the intercooler to a first preset temperature and increase the EGR rate to the first default EGR rate.

[0023] The EGR valve control unit is used to control the opening degree of the EGR valve according to the switching speed when the engine switches from the first operating point to the second operating point; the speed of the second operating point is greater than the speed of the first operating point, and the load of the second operating point is greater than the load of the first operating point.

[0024] Optionally, the device further includes:

[0025] A preset time setting unit is used to set the preset time according to the magnitude of the EGR rate; the preset time ranges from 3 seconds to 180 seconds.

[0026] Optionally, the EGR valve control unit includes:

[0027] The EGR valve reduction subunit is used to reduce the opening of the EGR valve when the switching speed is less than the preset speed.

[0028] The EGR valve shut-off subunit is used to close the EGR valve when the switching speed is greater than or equal to a preset speed.

[0029] Optionally, the device further includes:

[0030] The dew point temperature calculation unit is used to calculate the dew point temperature of the engine after the intercooler based on the EGR rate, the proportion of water vapor in the air entering the engine, the proportion of water vapor in the EGR gas entering the engine, and the saturated water vapor pressure in the mixed gas environment.

[0031] A preset temperature calculation unit is used to add a preset dew point temperature to the dew point temperature to obtain a preset temperature; the preset dew point temperature ranges from 2°C to 6°C.

[0032] Optionally, the device further includes:

[0033] The second EGR rate reduction unit is used to control the opening of the EGR valve and reduce the EGR rate within a preset range after the engine has been running at the second operating point at the second default EGR rate for a preset time; the second default EGR rate is the EGR rate selected at the second operating point according to the principle of minimum fuel consumption.

[0034] The second EGR rate enhancement unit is used to control the heat dissipation controller in the intercooler to increase the intake air temperature of the engine after the intercooler to a second preset temperature and increase the EGR rate to the second default EGR rate.

[0035] Based on the above-mentioned method for preventing engine condensation, this application also discloses a system for preventing engine condensation, including a heat dissipation controller and an EGR valve;

[0036] The heat dissipation controller is used to control the flow rate of coolant flowing into the intercooler radiator;

[0037] The EGR valve is used to control the EGR rate.

[0038] Optionally, the heat dissipation controller includes a three-way valve and a bypass pipe. The three-way valve is used to control the coolant to circulate through the bypass pipe instead of the intercooler radiator.

[0039] Optionally, the heat dissipation controller includes an electric water pump for reducing the flow rate of coolant into the intercooler radiator by reducing its rotational speed.

[0040] This application discloses a method, device, and system for preventing engine condensation. After the engine has been running at a first default EGR rate for a preset time at a first operating point, the opening of the EGR valve is controlled to reduce the EGR rate within a preset range. Then, the cooling controller in the intercooler is controlled to raise the intake air temperature of the engine after the intercooler to a first preset temperature and raise the EGR rate to the first default EGR rate. By automatically adjusting the EGR rate and intake air temperature through the EGR valve and cooling controller, water vapor in the turbocharged gas can be effectively prevented from condensing on the intake system after the intercooler. Furthermore, when the engine switches from a low-speed, low-load first operating point to a high-speed, high-load second operating point, the opening of the EGR valve is controlled according to the switching speed to prevent the temperature from dropping too quickly and generating condensate. The problem of misfire during transient engine switching can be solved simply by controlling the components; the design is reasonable and the method is simple. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0042] Figure 1 This is a schematic flowchart of an engine anti-condensation control method disclosed in an embodiment of this application;

[0043] Figure 2 This is a schematic diagram of an engine component structure disclosed in an embodiment of this application;

[0044] Figure 3 This is a schematic diagram of another engine component structure disclosed in an embodiment of this application;

[0045] Figure 4 This is a schematic diagram of the structure of an engine anti-condensation control device disclosed in an embodiment of this application. Detailed Implementation

[0046] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0047] Example 1: This application discloses a method for engine anti-condensation control.

[0048] For details, please refer to Figure 1 The method for engine anti-condensation control disclosed in this embodiment includes the following steps:

[0049] Step 101: After the engine runs at the first default EGR rate for a preset time at the first operating point, control the opening of the EGR valve to reduce the EGR rate within a preset range.

[0050] In the method described in this embodiment, the first default EGR rate is the EGR rate selected based on the principle of minimum fuel consumption at the first operating point. For example, the default EGR rate at the operating point of 2000 rpm / 100 N·m is 20%, and its corresponding relationship can be obtained by looking up a table.

[0051] As an optional method, a preset time can be set before controlling the EGR valve opening. Specifically, the EGR rate is compared to a specified value. When the EGR rate is greater than the specified value, it indicates a higher EGR rate, and the preset time can be set to a first preset number of seconds, such as 45 seconds. When the EGR rate is less than or equal to the specified value, it indicates a lower EGR rate, and the preset time can be set to a second preset number of seconds, such as 50 seconds. The first preset number of seconds must be less than the second preset number of seconds, and the range between the first and second preset numbers is 3 to 180 seconds.

[0052] As an optional method, the preset range is 20% to 70% of the first default EGR rate. For example, after the engine runs at a 20% EGR rate for 45 seconds at the first operating point, the EGR valve opening is controlled to reduce its EGR rate to 10%.

[0053] Step 102: Control the heat dissipation controller in the intercooler to raise the intake air temperature of the engine after the intercooler to a first preset temperature and raise the EGR rate to the first default EGR rate.

[0054] In the method described in this embodiment, before raising the temperature to the first preset temperature, the dew point temperature of the engine after the intercooler can be calculated based on the EGR rate, the proportion of water vapor in the air entering the engine, the proportion of water vapor in the EGR gas entering the engine, and the saturated water vapor pressure in the air-fuel mixture. The dew point temperature refers to the temperature at which air cooling reaches saturation under constant water vapor content and pressure, i.e., the temperature at which water vapor and water reach equilibrium.

[0055] In the method described in this embodiment, the preset temperature is obtained by increasing the dew point temperature by a preset dew point temperature. The preset dew point temperature ranges from 2°C to 6°C. For example, if the dew point temperature is 30°C and the preset dew point temperature is 3°C, the preset temperature is 33°C.

[0056] Step 103: When the engine switches from the first operating point to the second operating point, the opening degree of the EGR valve is controlled according to the switching speed.

[0057] In the method described in this embodiment, the engine speed at the second operating point is greater than that at the first operating point, and the load at the second operating point is greater than that at the first operating point. Specifically, the opening of the EGR valve is controlled according to the switching speed when the engine switches operating conditions. When the switching speed is less than a preset speed, it indicates a slow switching, and the opening of the EGR valve can be appropriately reduced. When the switching speed is greater than or equal to the preset speed, it indicates a fast switching, and the EGR valve can be closed to prevent the pressurized gas from liquefying upon cooling.

[0058] As an alternative approach, when the engine design and calibration data are well matched, for example, when the engine's combustion system can tolerate more EGR, the intake of each cylinder is relatively uniform, the combustion cycle fluctuation of each cylinder is relatively small, and the engine's intake and exhaust timing, fuel injection timing, and ignition timing are all well matched with the transient switching process, then the engine's switching speed for different operating conditions is fast, and the EGR valve may not need to be closed.

[0059] In the method described in this embodiment, after the engine operating condition is switched, the engine can run at the second operating point at the second default EGR rate for a preset time, and then the opening of the EGR valve is controlled to reduce the EGR rate within a preset range. The second default EGR rate is the EGR rate selected at the second operating point based on the principle of minimum fuel consumption. Then, the cooling controller in the intercooler is controlled to raise the intake air temperature of the engine after the intercooler to the second preset temperature and raise the EGR rate to the second default EGR rate.

[0060] The method described in this embodiment is reasonably designed and simple. It can automatically adjust the EGR rate and intake air temperature by controlling only the components, effectively preventing water vapor in the turbocharged gas from condensing on the intake system after the intercooler. Furthermore, it takes into account the situation when the engine switches operating conditions, controlling the opening of the EGR valve according to the switching speed to prevent the temperature from dropping too quickly and causing condensation.

[0061] Example 2: This application discloses another method for upgrading an energy storage system. The method described in this example is for a case where the heat dissipation controller is an electronic water pump. Figure 2 This is a schematic diagram of an engine component structure disclosed in an embodiment of this application, such as... Figure 2 As shown:

[0062] The outlet of intake manifold 7 is connected to the intake passage of engine 1, the inlet of engine exhaust pipe 8 is connected to the exhaust passage of engine 1, and the outlet of engine intake pipe 2 is connected to the inlet of intake manifold 7. Along the intake airflow direction, air filter 3, compressor 4, intercooler 5, and throttle valve 6 are connected in series on engine intake pipe 2. Along the exhaust airflow direction, turbine 9, catalytic converter 10, and muffler 11 are connected in series on engine exhaust pipe 8. Turbine 9 is coaxially connected to compressor 4. The two ends of the intercooler water circulation pipe 12 are connected to the inlet and outlet of the intercooler 5, respectively. The electric water pump 13 and the intercooler radiator 14 are connected in series on the intercooler water circulation pipe 12. One end of the low-pressure EGR pipe 17 is connected to the engine exhaust pipe 8 between the catalytic converter 10 and the muffler 11. The other end of the low-pressure EGR pipe 17 is connected to the engine intake pipe 2 between the air filter 3 and the compressor 4. The EGR valve 15 and the EGR heat exchanger 16 are connected in series on the low-pressure EGR pipe 17.

[0063] In the method described in this embodiment, engine 1 operates stably at a first operating point of 2000 rpm / 100 N·m, with an EGR rate of 20% (the first default EGR rate), and the intake air temperature of the engine after intercooler 5 is 25°C. After engine 1 has been running at the first operating point for 45 seconds, the EGR rate is reduced from 20% to 10% by controlling EGR valve 15, and the intake air temperature of the engine after intercooler 5 is increased by reducing the speed of electric water pump 13. As the engine intake air temperature increases, the EGR rate also increases; when the engine intake air temperature reaches 35°C, the EGR rate also increases from 10% to 20%.

[0064] When engine 1 switches from the first operating point to the second operating point of 3000 rpm / 120 N·m, the EGR valve 15 is closed. When engine 1 reaches the second operating point, the EGR valve 15 is opened again.

[0065] When engine 1 is running stably at the second operating point, the EGR valve 15 is controlled to achieve the second default EGR rate of 22%. After engine 1 has been running at the second operating point for 45 seconds, the EGR rate is reduced from 22% to 11% by controlling the EGR valve 15, and the intake air temperature of the engine after intercooler 5 is increased by controlling the electric water pump 13. As the engine intake air temperature gradually increases, the EGR rate also increases. When the engine intake air temperature reaches 42°C, the EGR rate also increases from 11% to 22%.

[0066] Among them, the control of EGR rate is matched with the intake air temperature control of the engine after intercooler 5. Even if the engine runs stably for a long time at a certain operating point, there is no large water droplet generated on the intake pipe after intercooler 5, thereby preventing misfire when the engine switches from the first operating point to the second operating point.

[0067] One optional method is to calculate the dew point temperature, and then obtain the preset temperature, which is the desired intake air temperature of the engine after the intercooler 5. At the first operating point, with an EGR rate of 20%, the dew point temperature is 31℃, and the preset temperature is 35℃. At the second operating point, with an EGR rate of 22%, the dew point temperature is 38℃, and the preset temperature is 42℃.

[0068] Example 3: This application discloses another method for upgrading an energy storage system. The method described in this example is for a case where the heat dissipation controller is a three-way valve and a bypass pipe. Figure 3 This is a schematic diagram of another engine component structure disclosed in an embodiment of this application, as shown below. Figure 3 As shown:

[0069] A three-way valve 18 is connected in series on the intercooler water circulation pipe 12 between the electric water pump 13 and the intercooler radiator 14. Two ports of the three-way valve 18 are connected to the intercooler water circulation pipe 12, and the third port of the three-way valve 18 is connected to one port of the bypass pipe 19. The other port of the bypass pipe 19 is connected to the intercooler water circulation pipe 12 between the intercooler 5 and the intercooler radiator 14.

[0070] At this point, by controlling the three-way valve 18, the circulating water flowing through the intercooler 5 can bypass the intercooler radiator 14 and instead circulate through the bypass pipe 19. This causes the intake air temperature of the engine after the intercooler 5 to rise rapidly.

[0071] Compared to Embodiment 2, the method described in this embodiment can more quickly increase the intake air temperature of the engine after the intercooler 5. Especially when the electric water pump 13 has a minimum speed requirement, even when the electric water pump 13 is operating at the minimum speed, the circulating water in the intercooler 5 will dissipate heat through the intercooler radiator 14, and the intake air temperature of the engine after the intercooler 5 will rise more slowly.

[0072] Based on the engine anti-condensation control method disclosed in the above embodiments, this embodiment correspondingly discloses an engine anti-condensation control device. Please refer to... Figure 4 The engine anti-condensation control device includes: a first EGR rate reduction unit 401, a first EGR rate increase unit 402, and an EGR valve control unit 403;

[0073] The first EGR rate reduction unit 401 is used to control the opening of the EGR valve and reduce the EGR rate within a preset range after the engine has been running at the first default EGR rate for a preset time at the first operating point; the first default EGR rate is the EGR rate selected at the first operating point according to the principle of minimum fuel consumption.

[0074] The first EGR rate enhancement unit 402 is used to control the heat dissipation controller in the intercooler to increase the intake air temperature of the engine after the intercooler to a first preset temperature and increase the EGR rate to the first default EGR rate.

[0075] The EGR valve control unit 403 is used to control the opening of the EGR valve according to the switching speed when the engine switches from the first operating point to the second operating point; the speed of the second operating point is greater than the speed of the first operating point, and the load of the second operating point is greater than the load of the first operating point.

[0076] Optionally, the device further includes:

[0077] A preset time setting unit is used to set the preset time according to the magnitude of the EGR rate; the preset time ranges from 3 seconds to 180 seconds.

[0078] Optionally, the EGR valve control unit 403 includes:

[0079] The EGR valve reduction subunit is used to reduce the opening of the EGR valve when the switching speed is less than the preset speed.

[0080] The EGR valve shut-off subunit is used to close the EGR valve when the switching speed is greater than or equal to a preset speed.

[0081] Optionally, the device further includes:

[0082] The dew point temperature calculation unit is used to calculate the dew point temperature of the engine after the intercooler based on the EGR rate, the proportion of water vapor in the air entering the engine, the proportion of water vapor in the EGR gas entering the engine, and the saturated water vapor pressure in the mixed gas environment.

[0083] A preset temperature calculation unit is used to add a preset dew point temperature to the dew point temperature to obtain a preset temperature; the preset dew point temperature ranges from 2°C to 6°C.

[0084] Optionally, the device further includes:

[0085] The second EGR rate reduction unit is used to control the opening of the EGR valve and reduce the EGR rate within a preset range after the engine has been running at the second operating point at the second default EGR rate for a preset time; the second default EGR rate is the EGR rate selected at the second operating point according to the principle of minimum fuel consumption.

[0086] The second EGR rate enhancement unit is used to control the heat dissipation controller in the intercooler to increase the intake air temperature of the engine after the intercooler to a second preset temperature and increase the EGR rate to the second default EGR rate.

[0087] Based on the engine anti-condensation control method disclosed in the above embodiments, this embodiment discloses an engine anti-condensation control system, including a heat dissipation controller and an EGR valve;

[0088] The heat dissipation controller is used to control the flow rate of coolant flowing into the intercooler radiator;

[0089] The EGR valve is used to control the EGR rate.

[0090] Optionally, the heat dissipation controller includes a three-way valve and a bypass pipe. The three-way valve is used to control the coolant to circulate through the bypass pipe instead of the intercooler radiator.

[0091] Optionally, the heat dissipation controller includes an electric water pump for reducing the flow rate of coolant into the intercooler radiator by reducing its rotational speed.

[0092] The embodiments in this specification are described in a progressive manner. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant details can be found in the method section.

[0093] It should also be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0094] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0095] The features described in the embodiments of this specification can be substituted for or combined with each other, so that those skilled in the art can implement or use this application.

[0096] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for engine anti-condensation control, characterized in that, include: After the engine runs at the first default EGR rate for a preset time at the first operating point, the opening of the EGR valve is controlled to reduce the EGR rate within a preset range. The first default EGR rate is the EGR rate selected at the first operating point based on the principle of minimum fuel consumption. The heat dissipation controller in the intercooler is controlled to raise the intake air temperature of the engine after the intercooler to a first preset temperature and raise the EGR rate to the first default EGR rate. When the engine switches from the first operating point to the second operating point, the opening of the EGR valve is controlled according to the switching speed. The speed at the second operating point is greater than the speed at the first operating point, and the load at the second operating point is greater than the load at the first operating point; The step of controlling the opening degree of the EGR valve based on the comparison result between the switching speed and the preset speed includes: When the switching speed is less than the preset speed, the opening of the EGR valve is reduced; When the switching speed is greater than or equal to the preset speed, the EGR valve is closed; Before raising the intake air temperature of the engine after the intercooler to a first preset temperature, the method further includes: The dew point temperature of the engine after the intercooler is calculated based on the EGR rate, the proportion of water vapor in the air entering the engine, the proportion of water vapor in the EGR gas entering the engine, and the saturated water vapor pressure in the air-fuel mixture. The preset temperature is obtained by adding the dew point temperature to the preset temperature.

2. The method according to claim 1, characterized in that, Before controlling the opening degree of the EGR valve, the method further includes: The preset time is set according to the magnitude of the EGR rate; the preset time ranges from 3 seconds to 180 seconds.

3. The method according to claim 1, characterized in that, The preset dew point temperature ranges from 2°C to 6°C.

4. The method according to claim 1, characterized in that, After the engine switches from the first operating point to the second operating point, the method further includes: After the engine runs at the second default EGR rate for a preset time at the second operating point, the opening of the EGR valve is controlled to reduce the EGR rate within a preset range; the second default EGR rate is the EGR rate selected at the second operating point based on the principle of minimum fuel consumption. The heat dissipation controller in the intercooler is controlled to raise the intake air temperature of the engine after the intercooler to a second preset temperature and raise the EGR rate to a second default EGR rate.

5. A device for engine anti-condensation control, characterized in that, include: First EGR rate reduction unit, first EGR rate increase unit, and EGR valve control unit; The first EGR rate reduction unit is used to control the opening of the EGR valve and reduce the EGR rate within a preset range after the engine has been running at the first default EGR rate for a preset time at the first operating point; the first default EGR rate is the EGR rate selected at the first operating point according to the principle of minimum fuel consumption. The first EGR rate enhancement unit is used to control the heat dissipation controller in the intercooler to increase the intake air temperature of the engine after the intercooler to a first preset temperature and increase the EGR rate to the first default EGR rate. The EGR valve control unit is used to control the opening degree of the EGR valve according to the switching speed when the engine switches from the first operating point to the second operating point. The speed at the second operating point is greater than the speed at the first operating point, and the load at the second operating point is greater than the load at the first operating point; The EGR valve control unit includes: The EGR valve reduction subunit is used to reduce the opening of the EGR valve when the switching speed is less than the preset speed. The EGR valve shut-off subunit is used to close the EGR valve when the switching speed is greater than or equal to a preset speed. The device further includes: The dew point temperature calculation unit is used to calculate the dew point temperature of the engine after the intercooler based on the EGR rate, the proportion of water vapor in the air entering the engine, the proportion of water vapor in the EGR gas entering the engine, and the saturated water vapor pressure in the mixed gas environment. A preset temperature calculation unit is used to add a preset dew point temperature to the dew point temperature to obtain a preset temperature.

6. The apparatus according to claim 5, characterized in that, The device further includes: A preset time setting unit is used to set the preset time according to the magnitude of the EGR rate; the preset time ranges from 3 seconds to 180 seconds.

7. A system for preventing engine condensation, characterized in that, For implementing the method of any one of claims 1-4, the system includes a heat dissipation controller and an EGR valve; The heat dissipation controller is used to control the flow rate of coolant flowing into the intercooler radiator; The EGR valve is used to control the EGR rate.

8. The system according to claim 7, characterized in that, The heat dissipation controller includes a three-way valve and a bypass pipe. The three-way valve is used to control the coolant to circulate through the bypass pipe instead of the intercooler radiator.

9. The system according to claim 7, characterized in that, The heat dissipation controller includes an electric water pump, which is used to reduce the flow rate of coolant into the intercooler radiator by reducing its rotational speed.

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