Method, control device and readable storage medium for controlling an electric heating device of an exhaust gas aftertreatment system

Abstract

This invention provides a method, control device, and readable storage medium for controlling an electric heating device in an exhaust gas aftertreatment system. The method includes: determining whether an engine is running; if running, determining whether the engine coolant temperature is higher than a predetermined temperature; if not higher than the predetermined temperature, setting the electric heating device to maximum power; if higher than the predetermined temperature, determining whether the exhaust gas energy ratio is higher than a first predetermined value; if not higher than the first predetermined value, setting the electric heating device to maximum power; if higher than the first predetermined value, determining whether the exhaust gas energy ratio is higher than a second predetermined value greater than the first predetermined value; if higher than the second predetermined value, setting the electric heating device to a closed state; if not higher than the second predetermined value, adjusting the power of the electric heating device according to the exhaust gas energy ratio; the exhaust gas energy ratio is the ratio of real-time exhaust gas energy to a reference energy. According to this invention, energy waste or reduced exhaust gas treatment efficiency can be prevented.

Description

Technical Field

[0001] This invention relates to exhaust aftertreatment systems for diesel engines, and more particularly to a method, control device, and readable storage medium for controlling an electric heating device in an exhaust aftertreatment system. Background Technology

[0002] Vehicles using diesel engines are typically equipped with exhaust aftertreatment systems to reduce the levels of nitrogen oxides, particulate matter, and unburned hydrocarbons in the exhaust emissions. Figure 1 The diagram schematically illustrates an exhaust gas aftertreatment system equipped with an electric heating device. For example... Figure 1 As shown, the exhaust aftertreatment system 1 generally includes an oxidation catalyst 3 for oxidizing unburned hydrocarbons from the engine and a selective catalytic reduction (SCR) 5 for reducing nitrogen oxides to nitrogen using an aqueous urea solution. In the figure, the oxidation catalyst 3 and the SCR 5 are shown connected via an exhaust pipe; they can actually be assembled together. The exhaust aftertreatment system also includes a filter (not shown) for filtering particulate matter. With increasing emphasis on environmental protection, emission requirements for engine exhaust, especially nitrogen oxides, are becoming increasingly stringent. Although the conversion rate of nitrogen oxides to nitrogen by the SCR in existing exhaust aftertreatment systems has reached over 90% within a suitable temperature range, the conversion rate is highly temperature-dependent. During engine operation at low temperatures, especially during cold starts, the temperature of the entire exhaust aftertreatment system is relatively low. Therefore, a large portion of harmful emissions is generated during the cold start phase of the engine's operating cycle, for example, in the first few hundred seconds after a cold start. Of course, during periods of idling, such as when a vehicle is waiting at a traffic light (a prolonged low-speed operation), the temperature of the entire exhaust aftertreatment system may also be relatively low. Therefore, it has been proposed to install an electric heating device 7 in the exhaust aftertreatment system 1 to improve its performance, especially during engine cold starts, when temperatures are relatively low. Figure 1 The electric heating device 7 is located upstream of the oxidation catalyst 3, but the electric heating device 7 can also be located upstream of the selective catalytic reducer 5 or other possible locations. Figure 2 The circuit structure of the electric heating device is schematically shown. For example... Figure 2As shown, the circuit structure of the electric heating device includes a power supply 9 for supplying power to the electric heating device 7 and a relay 13 connected to the vehicle's electronic control unit (ECU) 11. The ECU 11 controls the relay 13 to connect or disconnect to enable or disable the electric heating device 7. One existing method for controlling the electric heating device is time-based continuous heating, such as maintaining continuous operation of the electric heating device for a predetermined time. Another method is intermittent heating based on the temperature of the electric heating device 7. The heating time of the former method cannot be adjusted according to the engine's operating conditions, and is therefore unintelligent. The latter method only considers temperature without considering exhaust gas quality, and is also one-sided. Both methods can lead to overheating and wasted energy, or insufficient heating resulting in low exhaust gas aftertreatment efficiency, which may lead to urea solution crystallization.

[0003] Therefore, existing methods for controlling electric heating devices in exhaust gas aftertreatment systems need to be improved. Summary of the Invention

[0004] One object of the present invention is to overcome the deficiencies in the prior art described above and to provide a method for controlling an electric heating device in an exhaust gas aftertreatment system. The method for controlling an electric heating device in an exhaust gas aftertreatment system according to the present invention can intelligently control the electric heating device, thereby preventing overheating or underheating, and thus avoiding energy waste or reduced exhaust gas aftertreatment efficiency.

[0005] According to one aspect of the present invention, a method is provided for controlling an electric heating device in an exhaust gas aftertreatment system, the method comprising:

[0006] Determine whether the engine is running; when the engine is not running, turn the electric heating device off and put it into a non-operating state.

[0007] When the engine is running, determine whether the engine coolant temperature is higher than a predetermined temperature. If the engine coolant temperature is not higher than the predetermined temperature, set the electric heating device to operate at maximum power.

[0008] When the engine coolant temperature is higher than the predetermined temperature, it is determined whether the exhaust gas energy ratio is higher than a first predetermined value. If the exhaust gas energy ratio is not higher than the first predetermined value, the electric heating device is set to the maximum power operating state.

[0009] If the exhaust gas energy ratio is higher than the first predetermined value, determine whether the exhaust gas energy ratio is higher than the second predetermined value, wherein the second predetermined value is greater than the first predetermined value. If the exhaust gas energy ratio is higher than the second predetermined value, put the electric heating device in the non-working off state.

[0010] If the exhaust gas energy ratio is not higher than the second predetermined value, the power of the electric heating device is adjusted according to the exhaust gas energy ratio;

[0011] The exhaust gas energy ratio is the ratio of the real-time energy of the exhaust gas to the reference energy.

[0012] According to another aspect of the present invention, a control device is provided, characterized in that it comprises:

[0013] Processor; and

[0014] A memory storing executable instructions, which, when executed, cause the processor to perform the method described above for controlling an electrically heated device in an exhaust gas aftertreatment system.

[0015] According to another aspect of the present invention, a readable storage medium is provided, characterized in that executable instructions are stored thereon, which, when executed, cause a machine to perform the method described above for controlling an electrically heated device for an exhaust gas aftertreatment system.

[0016] The method for controlling an electric heating device in an exhaust gas aftertreatment system according to the present invention controls and / or adjusts the heating power of the electric heating device based on the exhaust gas energy ratio, avoiding the one-sidedness of controlling and / or adjusting the heating power of the electric heating device solely based on temperature. This enables intelligent control of the electric heating device, thereby preventing overheating or underheating, and thus avoiding energy waste or reduced exhaust gas treatment efficiency. Attached Figure Description

[0017] Figure 1 The diagram schematically illustrates an exhaust gas aftertreatment system equipped with an electric heating device;

[0018] Figure 2 The circuit structure of the electric heating device is schematically shown.

[0019] Figure 3 A flowchart illustrating a method for controlling an electric heating device for an exhaust gas aftertreatment system according to the present invention is shown schematically.

[0020] Figure 4 The diagram schematically illustrates the relationship between the heating power of an electric heating device according to an embodiment of the present invention and the exhaust gas energy ratio R.

[0021] Figure 5 The relationship between the heating power of the electric heating device and the exhaust gas energy ratio R according to another embodiment of the present invention is schematically shown; and

[0022] Figure 6 The control device according to the present invention is shown schematically. Detailed Implementation

[0023] As is known, an engine typically includes the following states: standby, ready, cranking, running, stopping, and finish. The standby state refers to the state where the engine has completed initialization; the ready state refers to the state after the engine is powered on; the cranking state refers to the state where the engine ignites and its speed is greater than zero but lower than a certain speed (e.g., 400 rpm); the running state refers to the state where the engine can operate stably; the stopping state refers to the state where the engine is powered off but its speed is not zero; and the finish state refers to the state where the engine is powered off and its speed is zero. Since the duration of the engine states other than the running state is relatively short, the method of the electric heating device for controlling the exhaust aftertreatment system according to the present invention is mainly applicable to the running state of the engine.

[0024] The method for controlling the electric heating device of the exhaust gas aftertreatment system according to the present invention is an intelligent control method that considers not only the temperature of the exhaust gas but also its quality; that is, it controls the operation of the electric heating device of the exhaust gas aftertreatment system based on the energy of the exhaust gas. Specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0025] Figure 3 A flowchart illustrating a method for controlling an electrically heated device in an exhaust gas aftertreatment system according to the present invention is shown schematically. Figure 3 As shown, the method for controlling the electric heating device of the exhaust aftertreatment system according to the present invention is executed starting in step S1. In fact, the vehicle's electronic control unit automatically executes the method of the present invention after the engine is ignited. In step S2, the electronic control unit determines whether the engine is running. If the engine is not running, the electronic control unit 11 controls the relay 13 to be in the open state, thereby putting the electric heating device 7 in the non-operating closed state P. Off If the engine is running, proceed to step S3.

[0026] In step S3, the electronic control unit determines whether the engine coolant temperature is higher than a predetermined temperature. If the engine coolant temperature is not higher than the predetermined temperature, the electronic control unit 11 controls the relay 13 to be in the ON state, thereby activating the electric heating device 7 and placing it in the maximum electric heating power operating state P. On-Max The engine coolant temperature is measured in real time by a temperature sensor electrically connected to the electronic control unit 11. The preset temperature can be selected according to the engine model or control strategy requirements; for example, the preset temperature can be set to approximately 50°C. If the engine coolant temperature is higher than the preset temperature, step S4 is executed.

[0027] In step S4, the electronic control unit determines whether the exhaust gas energy ratio R is higher than a first predetermined value R1. If the exhaust gas energy ratio R is not higher than the first predetermined value R1, the electronic control unit 11 controls the relay 13 to be in the ON state, thereby putting the electric heating device 7 into the working state and into the working state of maximum electric heating power P. On-Max If the exhaust gas energy ratio R is higher than the first predetermined value R1, then proceed to step S5.

[0028] In step S5, the electronic control unit determines whether the exhaust gas energy ratio R is higher than a second predetermined value R2, wherein the second predetermined value R2 is greater than a first predetermined value R1. If the exhaust gas energy ratio R is higher than the second predetermined value R2, the electronic control unit 11 controls the relay 13 to be in the open state, thereby putting the electric heating device 7 in the non-operating off state P. Off If the exhaust gas energy ratio R is not higher than the second predetermined value R2, then proceed to step S6.

[0029] According to one embodiment of the present invention, in step S6, the electronic control unit 11 controls the relay 13 to be in the ON state, thereby putting the electric heating device 7 into the working state. Furthermore, the electronic control unit 11 controls the supply voltage of the power supply 9 according to the magnitude of the exhaust gas energy ratio R, thereby enabling real-time adjustment (or stepless continuous adjustment) of the electric heating power of the electric heating device 7, such as... Figure 4 As shown. In Figure 4 In the figure, the horizontal axis represents the exhaust gas energy ratio R, and the vertical axis P represents the electric heating power of the electric heating device 7.

[0030] Although according to Figure 4 The method shown allows for more precise control of the power of the electric heating device 7 to avoid energy waste, but it increases the complexity and difficulty of control. Alternatively, the electric heating device 7 can be controlled in stages based on the exhaust gas energy ratio R. Figure 5 The diagram schematically illustrates the relationship between the heating power of an electric heating device according to another embodiment of the present invention and the exhaust gas energy ratio R. Figure 5 In the diagram, the horizontal axis represents the exhaust gas energy ratio R, and the vertical axis P represents the electric heating power of the electric heating device 7. For example... Figure 5 As shown, in step S6, the electronic control unit determines whether the exhaust gas energy ratio R is higher than a third predetermined value R3, wherein the third predetermined value is greater than a first predetermined value R1 but less than a second predetermined value R2. If the exhaust gas energy ratio R is higher than the third predetermined value R3, the electronic control unit 11 controls the relay 13 to be in the ON state, thereby putting the electric heating device 7 into the working state and into the working state of minimum electric heating power P. On-MinThe minimum electric heating power is not zero. If the exhaust gas energy ratio R is not higher than the third predetermined value, the electronic control unit 11 controls the relay 13 to be in the on state, thereby putting the electric heating device 7 into the working state and into the working state P where the electric heating power is at the intermediate value. On-Mid Among them, the intermediate value of the electric heating power lies between the minimum and maximum electric heating power. Figure 5 In the illustrated embodiment, the electric heating device 7 is controlled by three power levels: maximum electric heating power (e.g., 7.2 kW), intermediate electric heating power (e.g., 5 kW), and minimum electric heating power (e.g., 3 kW). It should be understood that, depending on the needs of the control strategy, the electric heating device 7 can be controlled by even more power levels.

[0031] The method for controlling the electric heating device of the exhaust aftertreatment system according to the present invention can repeatedly perform the steps S2 to S6 described above during vehicle operation, and proceed to step S7 after the engine is powered off, that is, stop performing the method of the present invention.

[0032] In the method of the electric heating device for controlling an exhaust gas aftertreatment system according to the present invention, the exhaust gas energy ratio R can be defined as the ratio of the real-time energy of the exhaust gas to a reference energy. Since different energies can be used as the reference energy, the exhaust gas energy ratio R may also be different.

[0033] According to an embodiment of the present invention, the exhaust gas energy ratio R can be determined by the following formula:

[0034]

[0035] In formula (1), the molecule represents the real-time energy of the exhaust gas, where:

[0036] It represents the real-time mass flow rate of exhaust gas (kg / h), which can be calculated by the electronic control unit based on the fuel injection quantity and the fresh air input quantity;

[0037] Cp represents the heat capacity of the exhaust gas, which is a constant, for example, it can be 1.07 kJ / (kg·K);

[0038] T is the temperature of the exhaust gas upstream of the selective catalytic reduction unit in the exhaust aftertreatment system, which can be measured by a temperature sensor.

[0039] The denominator in formula (1) (i.e., the reference energy) represents the average energy of the exhaust gas during the transient cold cycle required by the relevant regulations, where:

[0040] This indicates the mass flow rate (kg / h) of exhaust gas during the transient cold cycle required by the relevant regulations. It can also be calculated by the electronic control unit based on the fuel injection quantity and fresh air input quantity when the engine is idling.

[0041] This indicates the average temperature of the exhaust gas during the transient cold cycle required by the relevant regulations; it can also be measured by a temperature sensor.

[0042] When the exhaust gas energy ratio R is determined by formula (1), the first predetermined value R1 can be, for example, 0.8, the second predetermined value R2 can be, for example, 1.2, and the third predetermined value R3 can be, for example, 1.0.

[0043] According to another embodiment of the present invention, the exhaust gas energy ratio R can be determined by the following formula:

[0044]

[0045] The numerator in formula (2) also represents the real-time energy of the exhaust gas, but the denominator in formula (2) (i.e., the reference energy) represents the energy required for the hydrolysis of the components of the real-time injected urea aqueous solution, where:

[0046] The mass flow rate (kg / h) of the real-time injected urea solution can be calculated by the electronic control unit based on the nitrogen oxide content measured by the nitrogen oxide sensor and the real-time mass flow rate of the exhaust gas.

[0047] Δh vap This represents the enthalpy of vaporization of the urea aqueous solution, and its value is 2350 kJ / kg.

[0048] When the exhaust gas energy ratio R is determined by formula (2), the first predetermined value R1 can be, for example, 0.5, the second predetermined value R2 can be, for example, 1.0, and the third predetermined value R3 can be, for example, 0.8.

[0049] Whether controlling the power of an electric heating device in real time or in stages, it can be achieved by changing the power supply voltage of the electric heating device, thereby changing the current flowing through the electric heating device, or by changing the resistance of the electric heating device.

[0050] Although the method of the present invention is performed by the vehicle's electronic control unit in the above preferred embodiments, it should be understood that it is also feasible to use other control devices, such as microcontrollers, including processors and memory, to perform the method of the present invention in place of the electronic control unit. Figure 6The control device according to the invention is schematically shown. The control device 20 according to the invention includes a processor 21 and a memory 23 storing executable instructions. When the executable instructions in the memory 23 are executed, the processor 21 causes the processor 21 to execute the method according to the invention for controlling an electrically heated device in an exhaust gas aftertreatment system.

[0051] The method for controlling an electric heating device in an exhaust gas aftertreatment system according to the present invention controls and / or adjusts the heating power of the electric heating device based on the exhaust gas energy ratio, avoiding the one-sidedness of controlling and / or adjusting the heating power of the electric heating device solely based on temperature. This enables intelligent control of the electric heating device, thereby preventing overheating or underheating, and thus avoiding energy waste or reduced exhaust gas treatment efficiency.

[0052] Although the present invention has been described in detail with reference to preferred embodiments, it should be understood that such detailed description is for illustrative purposes only and does not constitute a limitation thereof. The scope of the invention is determined by the technical solutions defined in the claims.

Claims

1. A method for controlling an electric heating device in an exhaust gas aftertreatment system, the method comprising: Determine whether the engine is running; when the engine is not running, ensure the electric heating device is in a non-operating, off state (P). Off ); When the engine is running, it is determined whether the engine coolant temperature is higher than a predetermined temperature. If the engine coolant temperature is not higher than the predetermined temperature, the electric heating device is set to operate at maximum power (P). On-Max ); When the engine coolant temperature is higher than the predetermined temperature, it is determined whether the exhaust gas energy ratio (R) is higher than a first predetermined value. If the exhaust gas energy ratio (R) is not higher than the first predetermined value (R1), the electric heating device is set to the maximum power operating state (P). On-Max ); If the exhaust gas energy ratio (R) is higher than the first predetermined value, determine whether the exhaust gas energy ratio (R) is higher than a second predetermined value (R2), wherein the second predetermined value (R2) is greater than the first predetermined value (R1). If the exhaust gas energy ratio (R) is higher than the second predetermined value (R2), put the electric heating device into the non-operating off state (P). Off ); If the exhaust gas energy ratio (R) is not higher than the second predetermined value (R2), the power of the electric heating device is adjusted according to the exhaust gas energy ratio (R); The exhaust gas energy ratio (R) is the ratio of the real-time energy of the exhaust gas to the reference energy.

2. The method for controlling the electric heating device of the exhaust gas aftertreatment system as described in claim 1, wherein, Adjusting the power of the electric heating device includes controlling the power of the electric heating device in real time according to the magnitude of the exhaust gas energy ratio (R).

3. The method for controlling the electric heating device of the exhaust gas aftertreatment system as described in claim 1, wherein, Adjusting the power of the electric heating device includes controlling the power of the electric heating device in stages according to the magnitude of the exhaust gas energy ratio (R).

4. The method for controlling the electric heating device of the exhaust gas aftertreatment system as described in claim 3, wherein, Adjusting the power of the electric heating device includes determining whether the exhaust gas energy ratio (R) is higher than a third predetermined value (R3), wherein the third predetermined value (R3) is greater than the first predetermined value (R1) but less than the second predetermined value (R2). If the exhaust gas energy ratio (R) is higher than the third predetermined value (R3), the electric heating device is set to operate at minimum power (P). On-Min ); If the exhaust gas energy ratio (R) is not higher than the third predetermined value (R3), the electric heating device is set to operate at intermediate power (P). On-Mid ( ), wherein the intermediate power is between the minimum power and the maximum power.

5. The method for controlling the electric heating device of the exhaust gas aftertreatment system as described in claim 4, wherein, The reference energy is the average energy of the exhaust gas during the transient cold cycle required by the relevant regulations, and the exhaust gas energy ratio (R) is calculated according to the following formula: in, This indicates the real-time mass flow rate of the exhaust gas. Indicates the heat capacity of exhaust gas. T The temperature of the exhaust gas is measured upstream of the selective catalytic reduction unit in the exhaust gas aftertreatment system. This indicates the mass flow rate of the exhaust gas during the transient cold cycle as required by relevant regulations. This indicates the average temperature of the exhaust gas during the transient cold cycle required by the relevant regulations.

6. The method for controlling the electric heating device of the exhaust gas aftertreatment system according to claim 5, wherein, The first predetermined value (R1) is 0.8, the second predetermined value (R2) is 1.2, and the third predetermined value (R3) is 1.

0.

7. The method for controlling the electric heating device of the exhaust gas aftertreatment system as described in claim 4, wherein, The reference energy is the energy required for the hydrolysis of components in the real-time injected urea aqueous solution, and the exhaust gas energy ratio (R) is calculated according to the following formula: in, This indicates the real-time mass flow rate of the exhaust gas. Indicates the heat capacity of exhaust gas. T It measures the temperature of the exhaust gas. This indicates the real-time mass flow rate of the urea solution being sprayed. This represents the enthalpy of vaporization of an aqueous urea solution.

8. The method for controlling the electric heating device of the exhaust gas aftertreatment system according to claim 7, wherein, The first predetermined value (R1) is 0.5, the second predetermined value (R2) is 1.0, and the third predetermined value (R3) is 0.

8.

9. The method for controlling the electric heating device of the exhaust gas aftertreatment system according to claim 1, wherein, The predetermined temperature is 50°C.

10. A control device, characterized in that, include: processor; as well as A memory storing executable instructions, which, when executed, cause the processor to perform a method for controlling an electrically heated device for an exhaust gas aftertreatment system as described in any one of claims 1 to 9.

11. The control device as claimed in claim 10, characterized in that, The control device is the vehicle's electronic control unit.

12. A readable storage medium, characterized in that, It stores executable instructions that, when executed, cause the machine to perform the method of controlling the electric heating device for an exhaust gas aftertreatment system as described in any one of claims 1 to 9.

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