A method and system for OBD diagnosis control based on a national seventh electric heating system

Abstract

This invention discloses an OBD diagnostic control method for a China VII electric heating system, involving an aftertreatment system. It collects the temperature test value of the exhaust gas at the output end of the electric heater and calculates the measured temperature rise energy based on the temperature test value, the engine after-turbo temperature, and the exhaust specific heat capacity. The method obtains the EHC model temperature rise energy through an EHC temperature rise energy model and obtains the EHC heating efficiency based on the ratio between the measured temperature rise energy and the EHC model temperature rise energy. The EHC heating efficiency is compared with a set threshold efficiency; if the EHC heating efficiency is less than or equal to the threshold efficiency, the electric heater is determined to be faulty. This invention also discloses an OBD diagnostic control system for a China VII electric heating system. This invention can determine whether the problem of excessive emissions and increased fuel consumption is caused by a decrease in heater heating efficiency due to aging or carbon buildup in the electric heater itself, thus providing technicians with accurate fault location and facilitating rapid maintenance and replacement of the electric heater.

Description

Technical Field

[0001] This invention relates to post-processing systems, and more specifically, to an OBD diagnostic control method and system based on a China VII electric heating system. Background Technology

[0002] like Figure 1 As shown, the China VII aftertreatment system for engines includes components such as cCSCR / ccASC, ufSCR / ufASC, DOC, CDPF, EHC (electric heating), two-stage nozzles, and a urea pump. When the electric heater (EHC) is activated during engine cold starts, the cCSCR rapidly heats up, raising the temperature of the preceding SCR to reach the urea injection temperature and reduce NOx emissions during cold starts. However, when the electric heater adsorbs a large amount of carbon particles or ages, its heating power decreases, resulting in longer heating times to reach the urea injection temperature, worsened fuel consumption, and excessive emissions. However, current technology can only identify cold-start emissions exceeding standards caused by EHC open-circuit or short-circuit faults, but cannot accurately identify emissions exceeding standards and increased fuel consumption caused by decreased heater heating efficiency due to aging or carbon buildup in the electric heater itself. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to address the shortcomings of the existing technology by providing an OBD diagnostic control method and system based on the China VII electric heating system. This method solves the problems that, after the China VII after-treatment system turns on the electric heater, in the absence of open circuits or other electrical faults in the electric heater, the engine exhaust gas temperature rise rate is slow and emissions do not meet standards during the cold start phase, and the electric heater has a long on-time and high fuel consumption, yet the fault point cannot be accurately diagnosed and located.

[0004] The present invention discloses an OBD diagnostic control method based on a China VII electric heating system. This method involves acquiring the exhaust temperature test value at the output end of the electric heater, and calculating the measured temperature rise energy based on the temperature test value, the engine turbine exhaust temperature, and the exhaust specific heat capacity. The method then obtains the EHC model temperature rise energy through an EHC temperature rise energy model, and obtains the EHC heating efficiency based on the ratio between the measured temperature rise energy and the EHC model temperature rise energy. Finally, the method compares the EHC heating efficiency with a set threshold efficiency. If the EHC heating efficiency is less than or equal to the threshold efficiency, the electric heater is determined to be faulty.

[0005] As a further improvement, the measured temperature rise energy is calculated using the following formula:

[0006] E1 = (T8 - T41) × Cp;

[0007] In the formula, E1 is the measured temperature rise energy; T8 is the measured temperature value of the exhaust gas at the output end of the electric heater; T41 is the engine turbine after-turbo temperature; and Cp is the exhaust specific heat capacity.

[0008] As a further improvement, the temperature rise energy model of the EHC is as follows:

[0009] E2=Ew×Ti-U×A×ΔT;

[0010] In the formula, E2 is the temperature rise energy of the EHC model; U is the thermal conductivity coefficient between the electric heater and the environment; A is the heat dissipation area between the electric heater and the environment; ΔT=T41-Tenv, T41 is the engine turbine back temperature, Tenv is the ambient temperature; Ew is the operating power of the electric heater; Ti is the on-time of the electric heater.

[0011] As a further improvement, the engine turbine temperature is obtained by looking up a table based on the engine speed, circulating oil volume, and engine operating mode.

[0012] An OBD diagnostic control system based on a China VII electric heating system includes,

[0013] A temperature sensor is installed in the exhaust pipe between the electric heater and the pre-stage SCR to collect temperature test values.

[0014] The ECU is used to determine whether the electric heater is faulty by applying the OBD diagnostic control method described above, based on the temperature test value, the engine turbocharger temperature model, and the EHC temperature rise energy model.

[0015] Beneficial effects

[0016] The advantages of this invention are: by analyzing and judging the efficiency of the electric heater through measured temperature rise energy and EHC model temperature rise energy, it is possible to determine whether the problem of excessive emissions and increased fuel consumption is caused by the aging of the electric heater body or carbon buildup, which leads to a decrease in heating efficiency. This provides technicians with accurate fault location, facilitates rapid maintenance and replacement of the electric heater, and avoids the problem of continuous deterioration of fuel consumption and emissions. Attached Figure Description

[0017] Figure 1 A schematic diagram of the structure of the China VII emission standard after-processing system;

[0018] Figure 2 This is a schematic diagram of the OBD diagnostic control method of the present invention. Detailed Implementation

[0019] The present invention will be further described below with reference to embodiments, but this does not constitute any limitation on the present invention. Any limited modifications made by any person within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0020] See Figure 2This invention discloses an OBD diagnostic control method for a China VII electric heating system. The method collects the temperature test value of the exhaust gas at the output end of the electric heater and calculates the measured temperature rise energy based on the temperature test value, the engine after-turbo temperature, and the exhaust specific heat capacity. The engine after-turbo temperature is... Figure 1 The temperature model at T41 is obtained by looking up tables based on engine speed, circulating oil volume, and engine operating mode. Specifically, the measured temperature rise energy is calculated using the following formula:

[0021] E1 = (T8 - T41) × Cp.

[0022] In the formula, E1 is the measured temperature rise energy; T8 is the measured temperature value of the exhaust gas at the output end of the electric heater; T41 is the engine turbine after-turbo temperature; and Cp is the exhaust specific heat capacity.

[0023] The temperature rise energy of the EHC model is obtained through the temperature rise energy model of the EHC. Specifically, the temperature rise energy model of the EHC is as follows:

[0024] E2=Ew×Ti-U×A×ΔT.

[0025] In the formula, E2 is the temperature rise energy of the EHC model; U is the thermal conductivity coefficient between the electric heater and the environment; A is the heat dissipation area between the electric heater and the environment; ΔT=T41-Tenv, T41 is the engine turbine back temperature, Tenv is the ambient temperature; Ew is the operating power of the electric heater; Ti is the on-time of the electric heater.

[0026] After obtaining the measured temperature rise energy and the EHC model temperature rise energy, the efficiency of the electric heater can be determined by comparing these two energy values, and the presence of a heating fault in the electric heater can be judged based on the efficiency. The specific judgment process is as follows.

[0027] The EHC heating efficiency is obtained based on the ratio between the measured temperature rise energy and the temperature rise energy of the EHC model. The EHC heating efficiency is compared with a set threshold efficiency. If the EHC heating efficiency is less than or equal to the threshold efficiency, the electric heater is determined to be faulty. The threshold efficiency can be set according to actual needs; this embodiment does not impose further limitations on it.

[0028] When emissions exceed standards and fuel consumption increases, analyzing the efficiency of the electric heater can reveal whether the decrease in heating efficiency is caused by factors such as aging of the heater body or carbon buildup. This provides technicians with accurate fault location, facilitating rapid maintenance and replacement of the electric heater, and preventing the continued deterioration of fuel consumption and emissions.

[0029] An OBD diagnostic control system based on a China VII electric heating system includes a temperature sensor and an ECU.

[0030] The temperature sensor is installed in the exhaust pipe between the electric heater and the pre-stage SCR to collect temperature test values. For example... Figure 1 The T8 position in the diagram is the installation location of the temperature sensor.

[0031] The ECU uses temperature test values, the engine turbocharger temperature model, and the EHC temperature rise energy model to determine whether the electric heater is faulty using the OBD diagnostic control method described above. This allows it to determine whether the reduced heating efficiency is caused by factors such as aging of the electric heater body or carbon buildup, providing technicians with accurate fault location and facilitating rapid maintenance and replacement of the electric heater, thus preventing further deterioration of fuel consumption and emissions.

[0032] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention, and these will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A method for OBD diagnostic control of a China VII electric heating system, characterized in that, The temperature of the exhaust gas at the output of the electric heater is collected, and the measured temperature rise energy is calculated based on the measured temperature, the engine after-turbo temperature, and the exhaust specific heat capacity. The EHC model temperature rise energy is obtained through the EHC temperature rise energy model, and the EHC heating efficiency is obtained based on the ratio between the measured temperature rise energy and the EHC model temperature rise energy. The EHC heating efficiency is compared with a set threshold efficiency. If the EHC heating efficiency is less than or equal to the threshold efficiency, the electric heater is determined to be faulty.

2. The OBD diagnostic control method based on a National VII electric heating system according to claim 1, characterized in that, The measured temperature rise energy is calculated using the following formula. E1 = (T8 - T41) × Cp; In the formula, E1 is the measured temperature rise energy; T8 is the measured temperature value of the exhaust gas at the output end of the electric heater; T41 is the engine turbine after-turbo temperature; and Cp is the exhaust specific heat capacity.

3. The OBD diagnostic control method based on a National VII electric heating system according to claim 1, characterized in that, The energy model for the temperature rise of the EHC is as follows: E2=Ew×Ti-U×A×ΔT; In the formula, E2 is the temperature rise energy of the EHC model; U is the thermal conductivity coefficient between the electric heater and the environment; A is the heat dissipation area between the electric heater and the environment; ΔT=T41-Tenv, T41 is the engine turbine back temperature, Tenv is the ambient temperature; Ew is the operating power of the electric heater; Ti is the on-time of the electric heater.

4. A method for OBD diagnostic control of a National VII electric heating system according to claim 1, 2, or 3, characterized in that, The engine turbine temperature is obtained by looking up a table based on the engine speed, circulating oil volume, and engine operating mode.

5. An OBD diagnostic control system based on a China VII electric heating system, characterized in that, include, A temperature sensor is installed in the exhaust pipe between the electric heater and the pre-stage SCR to collect temperature test values. The ECU is used to determine whether the electric heater is faulty based on the temperature test value, the engine turbocharger temperature model, and the EHC temperature rise energy model, using the OBD diagnostic control method as described in any one of claims 1-4.

Images