A heat capacity based thermal catalytic aftertreatment system and method

Abstract

The application discloses a thermal capacity-based thermal catalytic aftertreatment system and method, which comprises a first temperature acquisition module, a second temperature acquisition module and a heating power calculation module. c The first temperature acquisition module is used for acquiring the current temperature T e of the catalytic conversion device. c The second temperature acquisition module is used for acquiring the engine exhaust temperature T a . e The heating power calculation module is used for calculating the heating power P of a heating module according to the current temperature T c of the catalytic conversion device, the required temperature T a and the engine exhaust temperature T e , and the heating module is used for heating the exhaust gas. The system and method disclosed by the application reduce the influence of the strong time-varying exhaust flow temperature on the stability of the controller, effectively improve the temperature of the catalytic conversion device during the cold start period, make the catalytic conversion device reach the light-off temperature faster to reduce the emission of pollutants, and when the EHC heating device and the catalytic conversion device are in a high-temperature state, the heating program is turned off to prolong the service life of the system.

Description

Technical Field

[0001] This invention belongs to the field of engine aftertreatment technology, specifically relating to a thermal catalytic aftertreatment system and method based on heat capacity. Background Technology

[0002] Engines are widely used in various motorized equipment due to their wide power range and stable power output. However, the combustion of fossil fuels releases pollutants such as NOx, CO, and PM, which have adverse effects on the environment and human health.

[0003] Using catalytic converters to control engine emissions can effectively reduce pollutant concentrations. However, there is a gap between the efficient operating temperature range of the catalytic converter and the engine exhaust temperature, especially during engine cold starts. In this situation, thermal management technology is needed to raise the exhaust temperature, allowing the catalytic converter to operate within its efficient operating temperature range more quickly.

[0004] With the trend towards hybrid vehicles, electrothermal catalytic converters (EHC) are a promising thermal management technology. They utilize electric heating to raise exhaust gas, rapidly increasing the conversion efficiency of the catalytic converter, reducing the negative impact of low exhaust temperatures on pollutant emissions, and offering strong independence and flexibility without requiring changes to engine parameters. However, currently, there are no energy-efficient control methods for the electric heating device, preventing the catalytic converter from reaching its efficient operating temperature range quickly and economically. Consequently, some pollutants are still released into the air, contributing to environmental pollution. Summary of the Invention

[0005] In order to enable the electric heating device to heat up better so that the engine can better control pollutant emissions under low-temperature conditions such as cold start, the present invention provides a thermal catalytic aftertreatment system and method based on heat capacity.

[0006] A thermal catalytic post-treatment system based on heat capacity, which achieves one of the objectives of the present invention, includes: a first temperature acquisition module, a second temperature acquisition module, and a heating power calculation module;

[0007] The first temperature acquisition module is used to acquire the current temperature T of the catalytic conversion unit. c ;

[0008] The second temperature acquisition module is used to acquire the engine exhaust temperature T. e ;

[0009] The heating power calculation module is used to calculate the current temperature T of the catalytic conversion unit. c and required temperature T a Engine exhaust temperature T eCalculate the heating power P of the heating module, which is used to heat the exhaust gas of the engine.

[0010] Furthermore, it also includes a feedforward power calculation module for calculating power based on the engine exhaust temperature T. e The required temperature T of the catalytic conversion unit a Calculate the feedforward power P e The feedforward power P e Used to calculate the heating power P of the heating module.

[0011] Furthermore, it also includes a feedback correction module for adjusting the current temperature T of the catalytic conversion unit. c The required temperature T of the catalytic conversion unit a Calculate the power correction P c The power correction amount P c Used to adjust the heating power P of the heating module.

[0012] Furthermore, it also includes a flow acquisition module, which is used to acquire the engine exhaust flow rate, and the exhaust flow rate is used to calculate the feedforward power P of the catalytic converter. e .

[0013] Furthermore, it also includes a first heating control module, which is used to time the heating duration of a single heating cycle of the heating module. If the single heating duration is longer than the maximum allowable duration, the heating module is turned off and waits for a set duration before determining whether to turn it on again based on the required temperature of the catalytic conversion device and the current temperature.

[0014] Furthermore, it also includes a second heating control module, which is used to determine whether the current temperature of the catalytic conversion device is higher than the safety limit. If it is higher than the safety limit, the heating module is turned off, and the heating module is turned on again when the current temperature is lower than the required temperature.

[0015] A second objective of this invention is a thermocatalytic post-treatment method based on heat capacity, comprising the following steps:

[0016] Obtain the current temperature T of the catalytic converter c If the current temperature T c Temperature T less than the required temperature of the catalytic conversion unit a Then, based on the engine exhaust temperature T e The current temperature T of the catalytic conversion unit c and required temperature T a Calculate the heating power P of the heating module, and heat the exhaust gas of the engine according to the heating power P.

[0017] Furthermore, the method for calculating the heating power P includes:

[0018] P = P e +P c

[0019] In the formula:

[0020] P e : with engine exhaust temperature T e The required temperature T of the catalytic conversion unit a Related feedforward power;

[0021] P c : and the current temperature T of the catalytic conversion unit c The required temperature T of the catalytic conversion unit a The relevant power correction amount.

[0022] Furthermore, based on the principle of heat capacity, the calculation of the heating power P includes taking into account the engine exhaust temperature Te and the required temperature T of the catalytic converter. a Calculate the feedforward power Pe;

[0023] The calculation of the feedforward power Pe includes:

[0024]

[0025] In the formula:

[0026] θ e Here is the flow compensation coefficient, θ. e With engine exhaust flow F e Positive correlation;

[0027] m is the mass of the substrate of the catalytic conversion device;

[0028] c represents the specific heat capacity of the substrate of the catalytic conversion device;

[0029] T a The required temperature for the catalytic conversion unit;

[0030] T e Engine exhaust temperature;

[0031] τ represents the shortest heating time for a single heating cycle of the heating module.

[0032] Since the feedforward power Pe is only related to the exhaust flow rate and exhaust temperature, it cannot directly reflect the current state of the catalytic converter. Furthermore, the catalytic converter releases or absorbs heat during the chemical reaction, so it is necessary to read the current state of the catalytic converter to correct the heating power P. Therefore, further, based on the principle of heat capacity, the calculation of the heating power P includes taking into account the current temperature T of the catalytic converter. c The required temperature T of the catalytic conversion unit aCalculate the power correction P c ;

[0033]

[0034] In the formula:

[0035] θ c Here is the temperature compensation coefficient, θ. c It is negatively correlated with the substrate heat exchange efficiency of the catalytic conversion device;

[0036] m is the mass of the substrate of the catalytic conversion device;

[0037] c represents the specific heat capacity of the substrate of the catalytic conversion device;

[0038] T a The required temperature for the catalytic conversion unit;

[0039] T c This refers to the current temperature of the catalytic conversion unit;

[0040] τ represents the shortest heating time for a single heating cycle of the heating module.

[0041] Furthermore, when the current temperature T of the catalytic conversion unit c Greater than the safety limit T max Or the heating duration of a single heating cycle of the heating module exceeds the maximum allowable heating time τ. max When the temperature T of the catalytic converter is reached, the heating module is turned off; if the current temperature T of the catalytic converter is reached... c Greater than the safety limit T max If the current temperature of the catalytic converter is lower than the required temperature of the catalytic converter, the heating module will be turned on; if the heating duration of a single heating cycle of the heating module is greater than the maximum allowable heating time τ... max Wait for the set time before deciding whether to turn on the heating module.

[0042] Beneficial effects:

[0043] The system and method described in this invention regulate the temperature based on the heat capacity of the catalytic converter, which reduces the impact of the highly time-varying exhaust flow temperature on the stability of the controller. It can effectively increase the temperature of the catalytic converter during cold start, enabling the catalytic converter to reach the ignition temperature more quickly to reduce pollutant emissions. Furthermore, when the EHC heating device and the catalytic converter are in a high-temperature state, the heating program is shut down to protect the relevant devices and extend the working life of the system. Attached Figure Description

[0044] Figure 1 This is a schematic diagram illustrating the working principle of the thermocatalytic post-treatment system described in this invention;

[0045] Figure 2This is a simplified structural diagram of the thermocatalytic post-treatment system described in this invention;

[0046] Figure 3 This is a schematic diagram of the logic control of the thermocatalytic post-treatment method described in this invention.

[0047] Explanation of reference numerals in the attached drawings: 200 Engine; 201 First temperature sensor; 202 Flow sensor; 203 EHC heating device; 204 Second temperature sensor; 205 Electric heating controller; 206 Catalytic converter. Detailed Implementation

[0048] The following detailed embodiments are provided to explain the technical solutions of the claims of this invention, so that those skilled in the art can understand the claims. The scope of protection of this invention is not limited to the following specific embodiments. Any modifications made by those skilled in the art that incorporate the technical solutions of the claims but differ from the following detailed embodiments are also within the scope of protection of this invention.

[0049] In the description of this invention, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0050] The following is combined with Figure 1 and Figure 2 An embodiment of the system described in this invention is presented.

[0051] The thermocatalytic post-treatment system of the present invention includes: a first temperature acquisition module, a second temperature acquisition module, and a heating power calculation module;

[0052] like Figure 1 As shown, the second temperature acquisition module acquires the engine's exhaust temperature T. e The flow acquisition module acquires the engine's exhaust flow rate F. e This data is then fed back to the heating power calculation module, specifically to the feedforward power calculation module within the heating power calculation module. The feedforward power calculation module calculates the power based on the engine's exhaust temperature T. e Calculate the feedforward power P e The first temperature acquisition module acquires the current temperature T of the catalytic conversion unit. c This information is then fed back to the heating power calculation module, specifically to the feedback correction module within the heating power calculation module. The feedback correction module adjusts the temperature T of the catalytic converter based on the current temperature T of the catalytic converter. c Calculate the corrected power P c According to the feedforward power P e and corrected power P c The heating power P of the heating module is set to raise the temperature of the incoming gas from the engine, so that the catalytic converter can be quickly heated to the high-efficiency operating range, thereby better controlling the emission of pollutants.

[0053] like Figure 2 As shown, the first temperature acquisition module is the second temperature sensor 204, which is placed on the catalytic conversion device 206 to collect the current temperature T of the catalytic conversion device 206. c And feed it back to the heating power calculation module;

[0054] The second temperature acquisition module is the first temperature sensor 201, which is placed between the engine 200 and the electro-catalytic converter (EHC) heating device 203, and is used to acquire the engine exhaust temperature T. e And feed it back to the heating power calculation module;

[0055] The heating power calculation module is used to calculate the current temperature T of the catalytic conversion unit. c The required temperature T of the catalytic conversion unit a Engine exhaust temperature T e Calculate the heating power P of the heating module. The heating module can be an electric heating catalytic converter (EHC) heating device used to heat the exhaust gas of the engine. One end of it is connected to the exhaust port of the engine, and the other end is connected to the catalytic converter. The exhaust gas of the engine is heated by the electric heating control module, so that the catalytic converter can quickly heat up to reach the high-efficiency operating range.

[0056] Preferably, it also includes a feedforward power calculation module for calculating power based on the engine exhaust temperature T. e The required temperature T of the catalytic conversion unit a Calculate the feedforward power P e The feedforward power P e Used to calculate the heating power P of the heating module.

[0057] Preferably, it further includes a feedback correction module for adjusting the current temperature T of the catalytic conversion unit. c The required temperature T of the catalytic conversion unit a Calculate the power correction P c The power correction amount P c Used to adjust the heating power P of the heating module.

[0058] Preferably, it also includes a flow acquisition module, which can be a flow sensor 202, placed between the engine and the EHC heating device, to collect the engine exhaust flow in real time and feed it back to the electric heating controller 205. The exhaust flow is used to calculate the feedforward power P of the catalytic converter heating device. e .

[0059] Preferably, it also includes a first heating control module, used to time the single heating duration of the heating module. If the single heating duration is longer than the maximum allowable duration, the heating module is turned off and waits for a set duration before determining whether to turn it on again based on the required temperature of the catalytic conversion device and the current temperature.

[0060] Preferably, it also includes a second heating control module, used to determine whether the current temperature of the catalytic conversion device is higher than the safety limit. If it is higher than the safety limit, the heating module is turned off, and the heating module is turned on again when the current temperature is lower than the required temperature.

[0061] The feedforward power calculation module, feedback correction module, first heating control module, and second heating control module can be located in... Figure 2 The electric heating controller 205 shown is connected to the first temperature sensor 201, the flow sensor 202, the EHC heating device 203, and the second temperature sensor 204.

[0062] The following is combined with Figure 3 An embodiment of the method described in this invention is presented.

[0063] S01. Determine whether engine 200 is started. If engine 200 is started, execute S02 to check the status of EHC aftertreatment system.

[0064] S02, measuring the temperature T of the catalytic converter 206 c ;

[0065] S03, Determine the temperature T of the catalytic converter 206. c Has the required temperature T been reached? a If the condition is met, return to step S01; otherwise, proceed to the next step.

[0066] S04. Use flow sensor 202 to measure the exhaust flow rate F of engine 200. e The exhaust temperature T of the engine 200 is measured using the first temperature sensor 201. e ;

[0067] S05, Calculate the feedforward power P e Feedforward power P e Used to calculate the heating power of the catalytic (EHC) heating device 203;

[0068] The feedforward power P e According to the flow rate F measured by flow sensor 202 e and the temperature T measured by the first temperature sensor 201 e The calculation method is as follows:

[0069]

[0070] In the formula:

[0071] θ e Here is the flow compensation coefficient, θ. e The flow rate F measured by flow sensor 202 e Positive correlation, and in this embodiment, its preferred range is 1.1-1.35;

[0072] m is the mass of the catalytic conversion unit 206 substrate;

[0073] c represents the specific heat capacity of the 206 substrate in the catalytic conversion unit;

[0074] T a The required temperature for catalytic conversion unit 206;

[0075] T e The temperature measured by the first temperature sensor 201;

[0076] τ represents the shortest heating time for a single cycle of the EHC heating device 203;

[0077] S06. Calculate the power correction P of the EHC heating device 203. c The power correction amount P c According to the temperature T measured by the second temperature sensor 204 c The heating power P of the EHC heating device 203 is adjusted in real time;

[0078] The P c The calculation method is as follows:

[0079]

[0080] In the formula:

[0081] θ c Here is the temperature compensation coefficient, θ. c The substrate heat exchange efficiency of the catalytic conversion device 206 is negatively correlated, and the preferred range in this embodiment is 1.17-1.54;

[0082] m is the mass of the catalytic conversion unit 206 substrate;

[0083] c represents the specific heat capacity of the 206 substrate in the catalytic conversion unit;

[0084] T a The required temperature for catalytic conversion unit 206;

[0085] T c The temperature measured by the second temperature sensor 204;

[0086] τ represents the shortest heating time for a single cycle of the EHC heating device 203;

[0087] S07. If the EHC heating device 203 is not started, the EHC heating device 203 shall be turned on with heating power P to heat the incoming gas and raise the temperature T of the downstream catalytic converter 206. c To enable it to reach the required temperature T a The heating duration T of the EHC heating device is timed, otherwise the heating duration T is accumulated; and if no emergency shutdown signal is received, the EHC heating device 203 will continue to heat for at least τ after it is turned on.

[0088] In this embodiment, the heating power P is calculated as follows:

[0089] P = P e +P c

[0090] Preferably, in order to save energy and protect the EHC heating device 203; when the heating power P of the EHC heating device 203 is greater than or equal to P max When using the maximum allowable heating power P max Heating;

[0091] S08, Determine whether the EHC heating time T is less than the maximum allowable heating time τ of the EHC heating device 203. max ;

[0092] If T < τ max Jump to S09;

[0093] Otherwise, turn off the EHC heating device 203; after the shutdown time of the heating device 203 reaches the expected stop time kτ, reset the heating time T of the EHC heating device 203 to 0; return to step S01.

[0094] S09, If the temperature T of the catalytic conversion unit 206 c ≥ Safety Limit T max If the EHC heating device 203 is turned off to alleviate the thermal shock of the catalytic conversion device 206, then return to step S01.

[0095] It should be noted that S08 and S09 can be executed in interchangeable order or simultaneously. The heating duration T of the EHC heating device can be determined first, followed by the temperature T of the catalytic converter 206. c Alternatively, the catalytic conversion unit can be 206°C at temperature T. c The heating duration T of the EHC heating device is then determined. In terms of its internal function and logic, there is no strict execution order.

[0096] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0097] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

Claims

1. A thermocatalytic aftertreatment system based on heat capacity, characterized in that, include: First temperature acquisition module, second temperature acquisition module, heating power calculation module; The first temperature acquisition module is used to acquire the current temperature T of the catalytic conversion unit. c ; The second temperature acquisition module is used to acquire the engine exhaust temperature T. e ; The heating power calculation module is used to calculate the current temperature T of the catalytic conversion unit. c and required temperature T a Engine exhaust temperature T e Calculate the heating power P of the heating module; the heating module heats the incoming gas from the engine, enabling the catalytic converter to quickly reach its high-efficiency operating range. It also includes a feedforward power calculation module, used to calculate power based on engine exhaust temperature T. e The required temperature T of the catalytic conversion unit a Calculate the feedforward power P e The feedforward power P e Used to calculate the heating power P of the heating module; It also includes a flow acquisition module for acquiring engine exhaust flow, which is used to calculate the feedforward power P of the heating module. e ; Feedforward power P e The calculations include: ； In the formula: θ e Here is the flow compensation coefficient, θ. e With engine exhaust flow F e Related; m is the mass of the substrate of the catalytic conversion device; c represents the specific heat capacity of the substrate of the catalytic conversion device; T a The required temperature for the catalytic conversion unit; T e Engine exhaust temperature; τ represents the shortest heating time for a single heating cycle of the heating module; The method for calculating the heating power P includes: P=P e +P c In the formula: P e : with engine exhaust temperature T e The required temperature T of the catalytic conversion unit a Related feedforward power; P c : and the current temperature T of the catalytic conversion unit c The required temperature T of the catalytic conversion unit a The relevant power correction amount.

2. The thermocatalytic aftertreatment system based on heat capacity as described in claim 1, characterized in that, It also includes a feedback correction module, used to adjust the current temperature T of the catalytic converter based on the current temperature T. c The required temperature T of the catalytic conversion unit a Calculate the power correction P c The power correction amount P c Used to adjust the heating power P of the heating module.

3. The thermocatalytic aftertreatment system based on heat capacity as described in any one of claims 1 to 2, characterized in that, It also includes a first heating control module, which is used to time the heating duration of a single heating cycle of the heating module. If the single heating duration is longer than the maximum allowable duration, the heating module is turned off and waits for a set duration before determining whether to turn it on again based on the required temperature of the catalytic conversion device and the current temperature.

4. The thermocatalytic aftertreatment system based on heat capacity as described in any one of claims 1 to 2, characterized in that, It also includes a second heating control module, which is used to determine whether the current temperature of the catalytic conversion device is higher than the safety limit. If it is higher than the safety limit, the heating module is turned off and turned on again when the temperature is lower than the required temperature.

5. A thermocatalytic post-treatment method based on heat capacity for the system as described in claim 1, characterized in that, Obtain the current temperature T of the catalytic converter c If the current temperature T c Temperature T less than the required temperature of the catalytic conversion unit a Then, based on the engine exhaust temperature T e The current temperature T of the catalytic conversion unit c and required temperature T a Calculate the heating power P of the heating module, and heat the exhaust gas of the engine according to the heating power P.

6. The thermocatalytic post-treatment method based on heat capacity as described in claim 5, characterized in that, The calculation of the heating power P includes taking into account the current temperature T of the catalytic converter. c The required temperature T of the catalytic conversion unit a Calculate the power correction P c ; ； In the formula: θ c Here is the temperature compensation coefficient, θ. c Related to the substrate heat exchange efficiency of the catalytic conversion device; m is the mass of the substrate of the catalytic conversion device; c represents the specific heat capacity of the substrate of the catalytic conversion device; T a The required temperature for the catalytic conversion unit; T c This refers to the current temperature of the catalytic conversion unit; τ represents the shortest heating time for a single heating cycle of the heating module.

7. The thermocatalytic post-treatment method based on heat capacity as described in claim 5, characterized in that, When the current temperature T of the catalytic conversion unit c Greater than the safety limit T max Or the heating duration of a single heating cycle of the heating module exceeds the maximum allowable heating time τ. max When the temperature T of the catalytic converter is reached, the heating module is turned off; if the current temperature T of the catalytic converter is reached... c Greater than the safety limit T max If the current temperature of the catalytic converter is lower than the required temperature of the catalytic converter, the heating module will be turned on; if the heating duration of a single heating cycle of the heating module is greater than the maximum allowable heating time τ... max Wait for the set time before deciding whether to turn on the heating module.

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