Dual-stage three-way catalyst efficiency diagnosis system and method

Abstract

The present invention relates to a dual-stage three-way catalyst efficiency diagnosis system, comprising a first-stage three-way catalyst, a second-stage three-way catalyst, a first-stage temperature sensor, and a second-stage temperature sensor; the present invention also relates to a dual-stage three-way catalyst efficiency diagnosis method, comprising the steps of obtaining a first maximum oxygen storage capacity, a second maximum oxygen storage capacity, a third maximum oxygen storage capacity, a fourth maximum oxygen storage capacity, a first-stage three-way catalyst corrected maximum oxygen storage capacity, a first-stage three-way catalyst corrected critical state maximum oxygen storage capacity, a second-stage three-way catalyst corrected maximum oxygen storage capacity, and a second-stage three-way catalyst corrected critical state maximum oxygen storage capacity; obtaining a first cumulative time, a second cumulative time, a third cumulative time, a fourth cumulative time, a fifth cumulative time, and a sixth cumulative time; defining an efficiency interval; obtaining a dual-stage three-way catalyst overall efficiency; and obtaining a dual-stage three-way catalyst efficiency diagnosis result. The present invention monitors the efficiency of the dual-stage TWC in real time and effectively.

Description

Technical Field

[0001] The invention relates to the technical field of natural gas engine tail gas purification treatment control, and in particular to a two-stage three-way catalyst efficiency diagnosis system and method. Background Art

[0002] With the upgrade of gas engine emission regulations, the three-way catalyst (TWC) is used to treat engine exhaust (NOX, CO, HC), and the efficiency of TWC needs to be monitored in real time and effectively. At the same time, in order to reduce the cost of TWC, a two-stage TWC is needed; the first-stage TWC has a large surface area and a high coating density, which is mainly used for rapid redox reactions, and the second-stage TWC is longer and has a low coating density, which is mainly used to capture emissions escaping from the first stage.

[0003] In order to effectively determine the efficiency of TWC in real time, typical existing technologies are as follows:

[0004] 1. The Chinese patent application with application publication number CN114233446A and invention name “A method, device and equipment for diagnosing efficiency of three-way catalyst” discloses the following technical solutions:

[0005] A method for diagnosing the efficiency of a three-way catalytic converter: judging whether to enter the three-way catalyst efficiency diagnosis through vehicle operation data, calculating the oxygen storage capacity of the three-way catalyst at this time when the diagnostic conditions are met, and when the oxygen storage capacity is less than the corresponding limit value, enriching the fuel-air ratio to consume the oxygen stored inside the three-way catalyst, and then filling the three-way catalyst with oxygen by diluting the fuel-air ratio; judging whether the efficiency of the three-way catalyst meets the requirements by checking the maximum oxygen filling capacity.

[0006] 2. The Chinese patent application with application publication number CN114856777A and invention name “Two-stage three-way catalytic converter oxygen cleaning control method, device, vehicle and storage medium” discloses the following technical solutions:

[0007] A method for diagnosing the efficiency of a two-stage three-way catalytic converter: determining the efficiency of the first-stage three-way catalyst by comparing the oxygen storage amount of the first-stage three-way catalyst with the corresponding limit value, then determining the efficiency of the second-stage three-way catalyst by comparing the oxygen storage amount of the second-stage three-way catalyst with the corresponding limit value, and then determining which stage of the three-way catalyst needs to be cleared of oxygen based on the efficiencies of the front and rear stages of the three-way catalyst.

[0008] In addition, most of the other existing technologies enter the diagnosis through specific operating conditions (such as fuel cut-off, reverse towing), and then enrich or dilute the fuel-air ratio, and finally determine whether the maximum oxygen filling amount or the corresponding oxygen filling time meets the requirements to perform three-way catalyst efficiency diagnosis.

[0009] The defects of the prior art are:

[0010] 1. The existing technology requires the three-way catalyst efficiency diagnosis to be performed under specific working conditions, which makes it impossible to perform real-time monitoring. Furthermore, the fuel-air ratio needs to be enriched or diluted, which will affect gas consumption and driving experience.

[0011] 2. Since the existing technology uses the maximum oxygen filling amount or oxygen filling time as the standard for three-way catalyst efficiency diagnosis, and the calculation of the maximum oxygen filling amount or oxygen filling time is related to the rear oxygen sensor, if the rear oxygen sensor fails, diagnosis cannot be performed;

[0012] 3. Since the existing technology for efficiency diagnosis of a two-stage three-way catalyst is to evaluate the efficiency of the front and rear two-stage three-way catalysts separately, it is impossible to directly measure the overall efficiency of the two-stage three-way catalyst. Summary of the invention

[0013] In view of the above problems, the present invention provides a dual-stage three-way catalyst efficiency diagnosis system and method, the purpose of which is to monitor the efficiency of the dual-stage TWC in real time and effectively.

[0014] To solve the above problems, the technical solution provided by the present invention is:

[0015] A two-stage three-way catalyst efficiency diagnostic system comprises a first-stage three-way catalyst, a second-stage three-way catalyst, a first-stage temperature sensor, a second-stage temperature sensor, and an exhaust flow sensor; wherein:

[0016] The first-stage temperature sensor is arranged at the inlet of the first-stage three-way catalyst and is used to collect the temperature of the first-stage three-way catalyst;

[0017] The second-stage temperature sensor is arranged at the inlet of the second-stage three-way catalyst and is used to collect the temperature of the second-stage three-way catalyst;

[0018] The exhaust flow sensor is arranged at the exhaust pipe outlet and is used to collect exhaust flow data.

[0019] Preferably, it also includes a first-stage fresh three-way catalyst oxygen storage capacity table, a second-stage fresh three-way catalyst oxygen storage capacity table, a first critical aged three-way catalyst oxygen storage capacity table, and a second critical aged three-way catalyst oxygen storage capacity table; wherein:

[0020] The first-stage fresh three-way catalyst oxygen storage capacity table is a two-dimensional table, including the first-stage three-way catalyst temperature and the first maximum oxygen storage capacity; each first-stage three-way catalyst temperature uniquely corresponds to one first maximum oxygen storage capacity;

[0021] The second-stage fresh three-way catalyst oxygen storage capacity table is a two-dimensional table, including the second-stage three-way catalyst temperature and the second maximum oxygen storage capacity; each second-stage three-way catalyst temperature uniquely corresponds to one second maximum oxygen storage capacity;

[0022] The first critical aged three-way catalyst oxygen storage capacity table is a two-dimensional table, including the first-stage three-way catalyst temperature and the third maximum oxygen storage capacity; each first-stage three-way catalyst temperature uniquely corresponds to one third maximum oxygen storage capacity;

[0023] The second critical aged state three-way catalyst oxygen storage capacity table is a two-dimensional table, including the second-stage three-way catalyst temperature and the fourth maximum oxygen storage capacity; each second-stage three-way catalyst temperature uniquely corresponds to one fourth maximum oxygen storage capacity.

[0024] Preferably, it also includes a first-stage three-way catalyst oxygen storage capacity correction table and a second-stage three-way catalyst oxygen storage capacity correction table; wherein:

[0025] The first-stage three-way catalyst oxygen storage capacity correction table is a two-dimensional table, including the exhaust flow data, the engine speed and the first-stage oxygen storage efficiency coefficient; each combination of the exhaust flow data and the engine speed uniquely corresponds to one first-stage oxygen storage efficiency coefficient;

[0026] The second-stage three-way catalyst oxygen storage capacity correction table is a two-dimensional table, which includes the exhaust flow data, the engine speed and the second-stage oxygen storage efficiency coefficient; each combination of the exhaust flow data and the engine speed uniquely corresponds to one second-stage oxygen storage efficiency coefficient.

[0027] A two-stage three-way catalyst efficiency diagnosis method using a two-stage three-way catalyst efficiency diagnosis system comprises the following steps:

[0028] S100. Obtain the first maximum oxygen storage capacity and the second maximum oxygen storage capacity; obtain the third maximum oxygen storage capacity and the fourth maximum oxygen storage capacity;

[0029] S200. Obtain the maximum oxygen storage capacity of the first-stage three-way catalyst after correction, the maximum oxygen storage capacity of the first-stage three-way catalyst after correction, the maximum oxygen storage capacity of the second-stage three-way catalyst after correction, and the maximum oxygen storage capacity of the second-stage three-way catalyst after correction;

[0030] S300. Statistically obtain the first cumulative time, the second cumulative time, the third cumulative time, the fourth cumulative time, the fifth cumulative time, and the sixth cumulative time;

[0031] S400. Determine an efficiency range for the first-stage three-way catalyst; and define the efficiency range for the second-stage three-way catalyst; the efficiency range includes a high efficiency range, a general efficiency range, and a low efficiency range;

[0032] S500. Calculate the overall efficiency of the two-stage three-way catalyst;

[0033] S600. Collect the current engine state and three-way catalyst operation mode; the engine state includes the operation state and the non-operation state; the three-way catalyst operation mode includes the oxygen removal mode, the heating mode, and other modes; then perform the following operations according to the engine state and the three-way catalyst operation mode:

[0034] If the current engine state is the operating state, and the three-way catalyst operating mode is not the oxygen removal mode, and the three-way catalyst operating mode is not the heating mode, then enter the dual-stage three-way catalyst efficiency diagnosis process;

[0035] If the current engine state is not the operating state, or the three-way catalyst operating mode is the oxygen removal mode, or the three-way catalyst operating mode is the heating mode, then the dual-stage three-way catalyst efficiency diagnosis is terminated;

[0036] S700. Execute the two-stage three-way catalyst efficiency diagnosis process to obtain and output a two-stage three-way catalyst efficiency diagnosis result; the two-stage three-way catalyst efficiency diagnosis result includes a two-stage three-way catalyst efficiency that is normal and a two-stage three-way catalyst efficiency that is low.

[0037] Preferably, S100 specifically includes the following steps:

[0038] S110. Obtaining the temperature of the first-stage three-way catalyst through the first-stage temperature sensor;

[0039] S120. Obtaining the temperature of the second-stage three-way catalyst through the second-stage temperature sensor;

[0040] S130. Perform a table lookup operation according to the temperature of the first-stage three-way catalyst, and find the first maximum oxygen storage capacity corresponding to the temperature of the first-stage three-way catalyst in the oxygen storage capacity table of the first-stage fresh three-way catalyst;

[0041] S140. Perform a table lookup operation according to the temperature of the second-stage three-way catalyst, and find the second maximum oxygen storage capacity corresponding to the temperature of the second-stage three-way catalyst in the oxygen storage capacity table of the second-stage fresh three-way catalyst;

[0042] S150. Perform a table lookup operation according to the temperature of the first stage three-way catalyst, and find the third maximum oxygen storage capacity corresponding to the temperature of the first stage three-way catalyst in the first critical aged state three-way catalyst oxygen storage capacity table;

[0043] S160. Perform a table lookup operation according to the temperature of the second-stage three-way catalyst, and look up the fourth maximum oxygen storage capacity corresponding to the temperature of the second-stage three-way catalyst in the second critical aged state three-way catalyst oxygen storage capacity table.

[0044] Preferably, S200 specifically includes the following steps:

[0045] S210. The exhaust flow data is collected by the exhaust flow sensor;

[0046] S220. Obtain engine speed from ECU via CAN bus;

[0047] S230. Perform a table lookup operation according to the exhaust flow data and the engine speed, and find the first-stage oxygen storage efficiency coefficient corresponding to the combination of the exhaust flow data and the engine speed in the first-stage three-way catalyst oxygen storage capacity correction table;

[0048] S240. Perform a table lookup operation according to the exhaust flow data and the engine speed, and find the second-stage oxygen storage efficiency coefficient corresponding to the combination of the exhaust flow data and the engine speed in the second-stage three-way catalyst oxygen storage capacity correction table;

[0049] S250. Calculate the maximum oxygen storage capacity of the first-stage three-way catalyst after correction, expressed as follows:

[0050] M′1=M1*η1

[0051] Wherein: M'1 is the maximum oxygen storage capacity of the first-stage three-way catalyst after correction; M1 is the first maximum oxygen storage capacity; η1 is the first-stage oxygen storage efficiency coefficient;

[0052] S260. Calculate the maximum oxygen storage capacity of the first-stage three-way catalyst after correction in the critical state, expressed as follows:

[0053] M'3=M3*η1

[0054] Wherein: M′3 is the critical maximum oxygen storage capacity of the first stage three-way catalyst after correction; M3 is the third maximum oxygen storage capacity;

[0055] S270. Calculate the maximum oxygen storage capacity of the second-stage three-way catalyst after correction, expressed as follows:

[0056] M'2=M2*η2

[0057] Wherein: M'2 is the maximum oxygen storage capacity of the second-stage three-way catalyst after correction; M2 is the second maximum oxygen storage capacity; η2 is the second-stage oxygen storage efficiency coefficient;

[0058] S280. Calculate the maximum oxygen storage capacity of the second-stage three-way catalyst after correction in the critical state, expressed as follows:

[0059] M'4=M4*η2

[0060] Wherein: M'4 is the critical maximum oxygen storage capacity of the second-stage three-way catalyst after correction; M4 is the fourth maximum oxygen storage capacity.

[0061] Preferably, S300 specifically includes the following steps:

[0062] S310. Record the total running time after the engine is started;

[0063] S320. Obtaining the oxygen storage capacity of the first-stage three-way catalyst during the entire operation of the engine;

[0064] S330. Obtaining the oxygen storage capacity of the second-stage three-way catalyst during the entire operation of the engine;

[0065] S340. Count the cumulative time that satisfies the condition expressed as follows as the first cumulative time:

[0066] T1∈T,when(0<M5<M3')

[0067] Wherein: T1 is the first accumulated time; T is the total running time after the engine is started; M5 is the oxygen storage capacity of the first stage three-way catalyst during the entire operation of the engine obtained in S320;

[0068] S350. Count the accumulated time that satisfies the condition expressed as follows as the second accumulated time:

[0069] T2∈T,when(M3'<M5<(M3'+M1') / 2)

[0070] Wherein: T2 is the second accumulated time;

[0071] S360. Count the accumulated time that satisfies the condition expressed as follows as the third accumulated time:

[0072] T3∈T,when((M3'+M1') / 2<M5<M1')

[0073] Wherein: T3 is the third accumulated time;

[0074] S370. Count the accumulated time that satisfies the condition expressed as follows as the fourth accumulated time:

[0075] T4∈T,when(0<M6<M4')

[0076] Wherein: T4 is the fourth accumulated time; M6 is the oxygen storage amount of the second-stage three-way catalyst during the entire operation of the engine obtained in S330;

[0077] S380. Count the accumulated time that satisfies the condition expressed as follows as the fifth accumulated time:

[0078] T5∈T,when(M4'<M6<(M4'+M2') / 2)

[0079] Wherein: T5 is the fifth accumulated time;

[0080] S390. Count the accumulated time that satisfies the condition expressed by the following formula as the sixth accumulated time:

[0081] T6∈T,when((M4'+M2') / 2<M6<M2')

[0082] Wherein: T6 is the sixth accumulated time.

[0083] Preferably, S400 specifically includes the following steps:

[0084] S410. According to the oxygen storage amount of the first-stage three-way catalyst during the entire operation of the engine obtained in S320, the efficiency range is defined for the first-stage three-way catalyst:

[0085] If (M3'+M1') / 2<M5<M1', the first stage three-way catalyst is defined as belonging to the high efficiency range;

[0086] If M3'<M5<(M3'+M1') / 2, the first stage three-way catalyst is defined as belonging to the general efficiency range; then the second accumulated time is equivalently calculated, specifically expressed as follows:

[0087] T2'=ε1*T2

[0088] Where: T2' is the equivalent second cumulative time; ε1 is the calibrated equivalent parameter, which is preset manually;

[0089] If 0<M5<M3', the first stage three-way catalyst is defined as belonging to the low efficiency range; then the first accumulated time is equivalently calculated, specifically expressed as follows:

[0090] T1'=ε2*T1

[0091] Where: T1' is the equivalent first cumulative time; ε2 is the calibrated equivalent parameter, which is preset manually;

[0092] S420. According to the oxygen storage amount of the second-stage three-way catalyst during the entire operation of the engine obtained in S330, the efficiency range is defined for the second-stage three-way catalyst:

[0093] If (M4'+M2') / 2<M6<M2', the second-stage three-way catalyst is defined as belonging to the high efficiency range;

[0094] If M4'<M6<(M4'+M2') / 2, the second stage three-way catalyst is defined as belonging to the general efficiency range; then the fifth accumulated time is equivalently calculated, specifically expressed as follows:

[0095] T5'=ε3*T5

[0096] Where: T5' is the equivalent fifth cumulative time; ε3 is the calibrated equivalent parameter, which is preset manually;

[0097] If 0<M6<M4', the second stage three-way catalyst is defined as belonging to the low efficiency range; then the fourth accumulated time is equivalently calculated, specifically expressed as follows:

[0098] T4'=ε4*T4

[0099] Wherein: T4' is the equivalent fourth cumulative time; ε4 is the calibrated equivalent parameter, which is preset manually.

[0100] Preferably, the overall efficiency of the two-stage three-way catalyst in S500 is expressed as follows:

[0101]

[0102] in: is the overall efficiency of the dual-stage three-way catalyst; γ is the ratio of the coating density of the first-stage three-way catalyst to the coating density of the second-stage three-way catalyst.

[0103] Preferably, the dual-stage three-way catalyst efficiency diagnosis process in S700 specifically includes the following steps:

[0104] S710. Compare the overall efficiency of the dual-stage three-way catalyst calculated in S500 with the manually preset efficiency calibration limit, and then perform the following operations according to the comparison result:

[0105] If the overall efficiency of the two-stage three-way catalyst is greater than the efficiency calibration limit, determining that the two-stage three-way catalyst efficiency diagnosis result is that the two-stage three-way catalyst efficiency is normal;

[0106] If the overall efficiency of the dual-stage three-way catalyst is not greater than the efficiency calibration limit, executing S720;

[0107] S720. Count the maintenance time of the overall efficiency of the two-stage three-way catalyst being no greater than the efficiency calibration limit; then perform the following operations according to the maintenance time:

[0108] If the maintenance time during which the overall efficiency of the dual-stage three-way catalyst is not greater than the efficiency calibration limit is less than the manually preset maintenance time threshold, then return to and execute S720 again;

[0109] If the maintenance time of the dual-stage three-way catalyst overall efficiency being not greater than the efficiency calibration limit is not less than the maintenance time threshold, it is determined that the dual-stage three-way catalyst efficiency diagnosis result is that the dual-stage three-way catalyst efficiency is low.

[0110] Compared with the prior art, the present invention has the following advantages:

[0111] 1. The present invention can monitor the efficiency of the two-stage TWC in real time, and does not require the fuel-air ratio to be enriched or diluted during engine operation;

[0112] 2. Since the present invention provides a new two-stage TWC efficiency calculation method, the accuracy and effectiveness of the two-stage TWC efficiency calculation are improved;

[0113] 3. Since the judgment basis of the system of the present invention is very intuitive, the overall efficiency of the two-stage three-way catalyst can be directly evaluated. BRIEF DESCRIPTION OF THE DRAWINGS

[0114] Figure 1 The figure is a schematic diagram of a method flow of a specific embodiment of the present invention. DETAILED DESCRIPTION

[0115] The present invention is further explained below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0116] A two-stage three-way catalyst efficiency diagnostic system comprises a first-stage three-way catalyst, a second-stage three-way catalyst, a first-stage temperature sensor, a second-stage temperature sensor, and an exhaust flow sensor; wherein:

[0117] The first-stage temperature sensor is arranged at the inlet of the first-stage three-way catalyst and is used to collect the temperature of the first-stage three-way catalyst.

[0118] The second-stage temperature sensor is arranged at the inlet of the second-stage three-way catalyst and is used to collect the temperature of the second-stage three-way catalyst.

[0119] The exhaust flow sensor is arranged at the exhaust pipe outlet to collect exhaust flow data.

[0120] In this specific embodiment, it also includes a first-stage fresh three-way catalyst oxygen storage capacity table, a second-stage fresh three-way catalyst oxygen storage capacity table, a first critical aged three-way catalyst oxygen storage capacity table, and a second critical aged three-way catalyst oxygen storage capacity table; wherein:

[0121] The oxygen storage capacity table of the first-stage fresh three-way catalyst is a two-dimensional table, including the first-stage three-way catalyst temperature and the first maximum oxygen storage capacity; each first-stage three-way catalyst temperature uniquely corresponds to a first maximum oxygen storage capacity.

[0122] The second-stage fresh three-way catalyst oxygen storage capacity table is a two-dimensional table, including the second-stage three-way catalyst temperature and the second maximum oxygen storage capacity; each second-stage three-way catalyst temperature uniquely corresponds to a second maximum oxygen storage capacity.

[0123] It should be noted that the first-stage fresh three-way catalyst oxygen storage capacity table and the second-stage fresh three-way catalyst oxygen storage capacity table are both obtained by performing oxygen storage operations on fresh three-way catalysts at different temperatures, and filling the measured maximum oxygen storage capacity into the corresponding position in the table.

[0124] The oxygen storage capacity table of the three-way catalyst in the first critical aged state is a two-dimensional table, including the first-stage three-way catalyst temperature and the third maximum oxygen storage capacity; each first-stage three-way catalyst temperature uniquely corresponds to a third maximum oxygen storage capacity.

[0125] The second critical aged state three-way catalyst oxygen storage capacity table is a two-dimensional table, including the second-stage three-way catalyst temperature and the fourth maximum oxygen storage capacity; each second-stage three-way catalyst temperature uniquely corresponds to a fourth maximum oxygen storage capacity.

[0126] It should be noted that the critical aged three-way catalyst refers to the three-way catalyst that can just ensure qualified exhaust emissions.

[0127] In this specific embodiment, it also includes a first-stage three-way catalyst oxygen storage capacity correction table and a second-stage three-way catalyst oxygen storage capacity correction table; wherein:

[0128] The first-stage three-way catalyst oxygen storage capacity correction table is a two-dimensional table, including exhaust flow data, engine speed and first-stage oxygen storage efficiency coefficient; each combination of exhaust flow data and engine speed uniquely corresponds to a first-stage oxygen storage efficiency coefficient.

[0129] The second-stage three-way catalyst oxygen storage capacity correction table is a two-dimensional table, which includes exhaust flow data, engine speed and second-stage oxygen storage efficiency coefficient; each combination of exhaust flow data and engine speed uniquely corresponds to a second-stage oxygen storage efficiency coefficient.

[0130] like Figure 1 As shown, a two-stage three-way catalyst efficiency diagnosis method using a two-stage three-way catalyst efficiency diagnosis system comprises the following steps:

[0131] S100. Obtain a first maximum oxygen storage capacity and a second maximum oxygen storage capacity; obtain a third maximum oxygen storage capacity and a fourth maximum oxygen storage capacity.

[0132] In this specific embodiment, S100 specifically includes the following steps:

[0133] S110. Obtain the temperature of the first-stage three-way catalyst through the first-stage temperature sensor.

[0134] S120. Obtain the temperature of the second-stage three-way catalyst through the second-stage temperature sensor.

[0135] S130. Perform a table lookup operation according to the temperature of the first-stage three-way catalyst, and find out the first maximum oxygen storage capacity corresponding to the temperature of the first-stage three-way catalyst in the oxygen storage capacity table of the first-stage fresh three-way catalyst.

[0136] S140. Perform a table lookup operation according to the temperature of the second-stage three-way catalyst, and find out the second maximum oxygen storage capacity corresponding to the temperature of the second-stage three-way catalyst in the second-stage fresh three-way catalyst oxygen storage capacity table.

[0137] S150. Perform a table lookup operation according to the temperature of the first-stage three-way catalyst, and find out the third maximum oxygen storage capacity corresponding to the temperature of the first-stage three-way catalyst in the first critical aged state three-way catalyst oxygen storage capacity table.

[0138] S160. Perform a table lookup operation according to the temperature of the second-stage three-way catalyst, and find out the fourth maximum oxygen storage capacity corresponding to the temperature of the second-stage three-way catalyst in the second critical aged state three-way catalyst oxygen storage capacity table.

[0139] S200. Obtain the maximum oxygen storage capacity of the first-stage three-way catalyst after correction, the maximum oxygen storage capacity of the first-stage three-way catalyst after correction in the critical state, the maximum oxygen storage capacity of the second-stage three-way catalyst after correction, and the maximum oxygen storage capacity of the second-stage three-way catalyst after correction in the critical state.

[0140] In this specific embodiment, S200 specifically includes the following steps:

[0141] S210. Collect exhaust flow data through an exhaust flow sensor.

[0142] S220. Obtain engine speed from ECU via CAN bus.

[0143] S230. Perform a table lookup operation based on the exhaust flow data and the engine speed, and look up the first-stage oxygen storage efficiency coefficient corresponding to the combination of the exhaust flow data and the engine speed in the first-stage three-way catalyst oxygen storage capacity correction table.

[0144] S240. Perform a table lookup operation based on the exhaust flow data and the engine speed, and find the second-stage oxygen storage efficiency coefficient corresponding to the combination of the exhaust flow data and the engine speed in the second-stage three-way catalyst oxygen storage capacity correction table.

[0145] S250. Calculate the maximum oxygen storage capacity of the first-stage three-way catalyst after correction, and express it as follows:

[0146] M'1=M1*η1

[0147] Wherein: M'1 is the maximum oxygen storage capacity of the first-stage three-way catalyst after correction; M1 is the first maximum oxygen storage capacity; η1 is the first-stage oxygen storage efficiency coefficient.

[0148] S260. Calculate the maximum oxygen storage capacity of the first-stage three-way catalyst after correction in the critical state, expressed as follows:

[0149] M'3=M3*η1

[0150] Wherein: M'3 is the maximum oxygen storage capacity of the first-stage three-way catalyst after correction in the critical state; M3 is the third maximum oxygen storage capacity.

[0151] S270. Calculate the maximum oxygen storage capacity of the second-stage three-way catalyst after correction, expressed as follows:

[0152] M'2=M2*η2

[0153] Wherein: M'2 is the maximum oxygen storage capacity of the second-stage three-way catalyst after correction; M2 is the second maximum oxygen storage capacity; η2 is the second-stage oxygen storage efficiency coefficient.

[0154] S280. Calculate the maximum oxygen storage capacity of the second-stage three-way catalyst after correction in the critical state, expressed as follows:

[0155] M'4=M4*η2

[0156] Wherein: M'4 is the critical maximum oxygen storage capacity of the second-stage three-way catalyst after correction; M4 is the fourth maximum oxygen storage capacity.

[0157] S300. Obtain a first cumulative time, a second cumulative time, a third cumulative time, a fourth cumulative time, a fifth cumulative time, and a sixth cumulative time through statistics.

[0158] In this specific embodiment, S300 specifically includes the following steps:

[0159] S310. Record the total running time after the engine is started.

[0160] S320. Obtain the oxygen storage amount of the first-stage three-way catalyst during the entire operation of the engine.

[0161] S330. Obtain the oxygen storage amount of the second-stage three-way catalyst during the entire operation of the engine.

[0162] S340. Count the cumulative time that satisfies the condition expressed by the following formula as the first cumulative time:

[0163] T1∈T,when(0<M5<M3')

[0164] Wherein: T1 is the first accumulated time; T is the total running time after the engine is started; M5 is the oxygen storage capacity of the first-stage three-way catalyst during the entire operation of the engine obtained in S320.

[0165] S350. Count the accumulated time that satisfies the condition expressed by the following formula as the second accumulated time:

[0166]

[0167] Wherein: T2 is the second cumulative time.

[0168] S360. Count the accumulated time that satisfies the condition expressed by the following formula as the third accumulated time:

[0169] T3∈T,when((M3'+M1') / 2<M5<M1')

[0170] Among them: T3 is the third accumulated time.

[0171] S370. Count the cumulative time that satisfies the condition expressed by the following formula as the fourth cumulative time:

[0172] T4∈T,when(0<M6<M4')

[0173] Wherein: T4 is the fourth accumulated time; M6 is the oxygen storage amount of the second-stage three-way catalyst during the entire operation of the engine obtained in S330.

[0174] S380. Count the accumulated time that satisfies the conditions expressed by the following formula as the fifth accumulated time:

[0175] T5∈T,when(M4'<M6<(M4'+M2') / 2)

[0176] Among them: T5 is the fifth accumulated time.

[0177] S390. Statistically accumulate the time that meets the condition expressed by the following formula as the sixth cumulative time:

[0178] T6 ∈ T, when ((M4'+M2') / 2 < M6 < M2')

[0179] Where: T6 is the sixth cumulative time.

[0180] S400. Define an efficiency range for the first-stage three-way catalyst; and define an efficiency range for the second-stage three-way catalyst; the efficiency range includes a high-efficiency range, a general-efficiency range, and a low-efficiency range.

[0181] In this specific embodiment, S400 specifically includes the following steps:

[0182] S410. Define an efficiency range for the first-stage three-way catalyst according to the oxygen storage amount of the first-stage three-way catalyst obtained in S320 during the entire operation of the engine:

[0183] If (M3'+M1') / 2 < M5 < M1', then define that the first-stage three-way catalyst belongs to the high-efficiency range.

[0184] If M3' < M5 < (M3'+M1') / 2, then define that the first-stage three-way catalyst belongs to the general-efficiency range; then perform an equivalent calculation on the second cumulative time, specifically expressed by the following formula:

[0185] T2' = ε1 * T2

[0186] Where: T2' is the equivalent second cumulative time; ε1 is the calibrated equivalent parameter, preset manually.

[0187] If 0 < M5 < M3', then define that the first-stage three-way catalyst belongs to the low-efficiency range; then perform an equivalent calculation on the first cumulative time, specifically expressed by the following formula:

[0188] T1' = ε2 * T1

[0189] Where: T1' is the equivalent first cumulative time; ε2 is the calibrated equivalent parameter, preset manually.

[0190] S420. Define an efficiency range for the second-stage three-way catalyst according to the oxygen storage amount of the second-stage three-way catalyst obtained in S330 during the entire operation of the engine:

[0191] If (M4'+M2') / 2 < M6 < M2', then define that the second-stage three-way catalyst belongs to the high-efficiency range.

[0192] If M4' < M6 < (M4' + M2') / 2, it is determined that the second-stage three-way catalyst belongs to the general efficiency range; then, the fifth cumulative time is equivalently calculated, which is specifically expressed by the following formula:

[0193] T5' = ε3 * T5

[0194] Where: T5' is the equivalent fifth cumulative time; ε3 is the calibrated equivalent parameter, which is preset manually.

[0195] If 0 < M6 < M4', it is determined that the second-stage three-way catalyst belongs to the low efficiency range; then, the fourth cumulative time is equivalently calculated, which is specifically expressed by the following formula:

[0196] T4' = ε4 * T4

[0197] Where: T4' is the equivalent fourth cumulative time; ε4 is the calibrated equivalent parameter, which is preset manually.

[0198] It should be noted that the principle of S400 is as follows:

[0199] The time is normalized. The catalytic efficiency of the three-way catalyst is related to the oxygen storage capacity of the three-way catalyst. Between the minimum oxygen storage capacity and the maximum oxygen storage capacity, the higher the oxygen storage capacity of the three-way catalyst, the higher the catalytic efficiency of the three-way catalyst. In the prior art, due to the aging of the three-way catalyst and the insufficient accuracy of the oxygen storage closed-loop control, it is impossible to ensure that the oxygen storage amount inside the three-way catalyst is always in the high efficiency range.

[0200] S500. Calculate the overall efficiency of the dual-stage three-way catalyst.

[0201] In this specific embodiment, the overall efficiency of the dual-stage three-way catalyst in S500 is expressed by the following formula:

[0202]

[0203] Where: is the overall efficiency of the dual-stage three-way catalyst; γ is the ratio of the coating density of the first-stage three-way catalyst to the coating density of the second-stage three-way catalyst.

[0204] S600. Collect the current engine state and the operation mode of the three-way catalyst; the engine state includes the running state and the non-running state; the operation mode of the three-way catalyst includes the oxygen cleaning mode, the heating mode, and other modes; then, the following operations are performed according to the engine state and the operation mode of the three-way catalyst:

[0205] If the current engine state is the running state, and the operation mode of the three-way catalyst is not the oxygen cleaning mode, and the operation mode of the three-way catalyst is not the heating mode, then enter the dual-stage three-way catalyst efficiency diagnosis process.

[0206] If the current engine state is not the running state, or the three-way catalyst operation mode is the oxygen removal mode, or the three-way catalyst operation mode is the heating mode, then this dual-stage three-way catalyst efficiency diagnosis is terminated.

[0207] It should be noted that the three-way catalyst basically does not work in the oxygen purification mode or heating mode, so it is not considered in this application.

[0208] S700. Execute the two-stage three-way catalyst efficiency diagnosis process to obtain and output the two-stage three-way catalyst efficiency diagnosis result; the two-stage three-way catalyst efficiency diagnosis result includes the two-stage three-way catalyst efficiency being normal and the two-stage three-way catalyst efficiency being low.

[0209] In this specific embodiment, the two-stage three-way catalyst efficiency diagnosis process in S700 specifically includes the following steps:

[0210] S710. Compare the overall efficiency of the two-stage three-way catalyst calculated in S500 with the manually preset efficiency calibration limit, and then perform the following operations according to the comparison result:

[0211] If the overall efficiency of the two-stage three-way catalyst is greater than the efficiency calibration limit, it is determined that the two-stage three-way catalyst efficiency diagnosis result is that the two-stage three-way catalyst efficiency is normal.

[0212] If the overall efficiency of the dual-stage three-way catalyst is not greater than the efficiency calibration limit, S720 is executed.

[0213] S720. Count the time during which the overall efficiency of the two-stage three-way catalyst is not greater than the efficiency calibration limit; then perform the following operations based on the maintenance time:

[0214] If the maintenance time during which the overall efficiency of the dual-stage three-way catalyst is not greater than the efficiency calibration limit is less than the manually preset maintenance time threshold, the process returns to and executes S720 again.

[0215] If the overall efficiency of the two-stage three-way catalyst is not greater than the efficiency calibration limit and the maintenance time is not less than the maintenance time threshold, it is determined that the two-stage three-way catalyst efficiency diagnosis result is that the two-stage three-way catalyst efficiency is low.

[0216] In the above detailed description, various features are grouped together in a single embodiment to simplify the disclosure. This method of disclosure should not be interpreted as reflecting an intention that the embodiments of the claimed subject matter require more features than are clearly stated in each claim. On the contrary, as reflected in the appended claims, the invention is in a state of having less than all the features of the disclosed individual embodiments. Therefore, the appended claims are hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment of the invention.

[0217] The disclosed embodiments are described above to enable any person skilled in the art to implement or use the present invention. Various modifications of these embodiments are obvious to those skilled in the art, and the general principles defined herein may also be applied to other embodiments without departing from the spirit and scope of the present disclosure. Therefore, the present disclosure is not limited to the embodiments given herein, but is consistent with the broadest scope of the principles and novel features disclosed in this application.

[0218] The above description includes examples of one or more embodiments. Of course, it is not possible to describe all possible combinations of components or methods for the purpose of describing the above embodiments, but it should be recognized by those skilled in the art that the various embodiments may be further combined and arranged. Therefore, the embodiments described herein are intended to cover all such changes, modifications and variations that fall within the scope of protection of the appended claims. In addition, with respect to the term "comprising" used in the specification or claims, the word is covered in a manner similar to the term "including", just as "including," is explained as a transitional word in the claims. In addition, any term "or" used in the specification of the claims is intended to mean "non-exclusive or".

[0219] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A dual-stage three-way catalyst efficiency diagnostic system, characterized in that: It includes a first-stage three-way catalyst, a second-stage three-way catalyst, a first-stage temperature sensor, a second-stage temperature sensor, and an exhaust flow sensor; wherein: The first-stage temperature sensor is arranged at the inlet of the first-stage three-way catalyst and is used to collect the temperature of the first-stage three-way catalyst; The second-stage temperature sensor is arranged at the inlet of the second-stage three-way catalyst and is used to collect the temperature of the second-stage three-way catalyst; The exhaust flow sensor is arranged at the exhaust pipe outlet and is used to collect exhaust flow data; The dual-stage three-way catalyst efficiency diagnostic system further comprises a first-stage fresh three-way catalyst oxygen storage capacity table, a second-stage fresh three-way catalyst oxygen storage capacity table, a first critical aged three-way catalyst oxygen storage capacity table, and a second critical aged three-way catalyst oxygen storage capacity table; wherein: The first-stage fresh three-way catalyst oxygen storage capacity table is a two-dimensional table, including the first-stage three-way catalyst temperature and the first maximum oxygen storage capacity; each first-stage three-way catalyst temperature uniquely corresponds to one first maximum oxygen storage capacity; The second-stage fresh three-way catalyst oxygen storage capacity table is a two-dimensional table, including the second-stage three-way catalyst temperature and the second maximum oxygen storage capacity; each second-stage three-way catalyst temperature uniquely corresponds to one second maximum oxygen storage capacity; The first critical aged three-way catalyst oxygen storage capacity table is a two-dimensional table, including the first-stage three-way catalyst temperature and the third maximum oxygen storage capacity; each first-stage three-way catalyst temperature uniquely corresponds to one third maximum oxygen storage capacity; The second critical aged three-way catalyst oxygen storage capacity table is a two-dimensional table, including the second-stage three-way catalyst temperature and the fourth maximum oxygen storage capacity; each second-stage three-way catalyst temperature uniquely corresponds to one fourth maximum oxygen storage capacity; The dual-stage three-way catalyst efficiency diagnostic system further comprises a first-stage three-way catalyst oxygen storage capacity correction table and a second-stage three-way catalyst oxygen storage capacity correction table; wherein: The first-stage three-way catalyst oxygen storage capacity correction table is a two-dimensional table, including the exhaust flow data, the engine speed and the first-stage oxygen storage efficiency coefficient; each combination of the exhaust flow data and the engine speed uniquely corresponds to one first-stage oxygen storage efficiency coefficient; The second-stage three-way catalyst oxygen storage capacity correction table is a two-dimensional table, which includes the exhaust flow data, the engine speed and the second-stage oxygen storage efficiency coefficient; each combination of the exhaust flow data and the engine speed uniquely corresponds to one second-stage oxygen storage efficiency coefficient.

2. A two-stage three-way catalyst efficiency diagnosis method using the two-stage three-way catalyst efficiency diagnosis system according to claim 1, characterized in that: The following steps are involved: S100. Obtain the first maximum oxygen storage capacity and the second maximum oxygen storage capacity; obtain the third maximum oxygen storage capacity and the fourth maximum oxygen storage capacity; S200. Obtain the maximum oxygen storage capacity of the first-stage three-way catalyst after correction, the maximum oxygen storage capacity of the first-stage three-way catalyst after correction, the maximum oxygen storage capacity of the second-stage three-way catalyst after correction, and the maximum oxygen storage capacity of the second-stage three-way catalyst after correction; S300. Statistically obtain the first cumulative time, the second cumulative time, the third cumulative time, the fourth cumulative time, the fifth cumulative time, and the sixth cumulative time; S400. Determine an efficiency range for the first-stage three-way catalyst; and define the efficiency range for the second-stage three-way catalyst; the efficiency range includes a high efficiency range, a general efficiency range, and a low efficiency range; S500. Calculate the overall efficiency of the two-stage three-way catalyst; S600. Collect the current engine state and three-way catalyst operation mode; the engine state includes the operation state and the non-operation state; the three-way catalyst operation mode includes the oxygen removal mode, the heating mode, and other modes; then perform the following operations according to the engine state and the three-way catalyst operation mode: If the current engine state is the operating state, and the three-way catalyst operating mode is not the oxygen removal mode, and the three-way catalyst operating mode is not the heating mode, then enter the dual-stage three-way catalyst efficiency diagnosis process; If the current engine state is not the operating state, or the three-way catalyst operating mode is the oxygen removal mode, or the three-way catalyst operating mode is the heating mode, then the dual-stage three-way catalyst efficiency diagnosis is terminated; S700. Execute the two-stage three-way catalyst efficiency diagnosis process to obtain and output a two-stage three-way catalyst efficiency diagnosis result; the two-stage three-way catalyst efficiency diagnosis result includes a two-stage three-way catalyst efficiency that is normal and a two-stage three-way catalyst efficiency that is low.

3. The dual-stage three-way catalyst efficiency diagnostic method according to claim 2, characterized in that: S100 specifically includes the following steps: S110. Obtaining the temperature of the first-stage three-way catalyst through the first-stage temperature sensor; S120. Obtaining the temperature of the second-stage three-way catalyst through the second-stage temperature sensor; S130. Perform a table lookup operation according to the temperature of the first-stage three-way catalyst, and find the first maximum oxygen storage capacity corresponding to the temperature of the first-stage three-way catalyst in the oxygen storage capacity table of the first-stage fresh three-way catalyst; S140. Perform a table lookup operation according to the temperature of the second-stage three-way catalyst, and find the second maximum oxygen storage capacity corresponding to the temperature of the second-stage three-way catalyst in the oxygen storage capacity table of the second-stage fresh three-way catalyst; S150. Perform a table lookup operation according to the temperature of the first stage three-way catalyst, and find the third maximum oxygen storage capacity corresponding to the temperature of the first stage three-way catalyst in the first critical aged state three-way catalyst oxygen storage capacity table; S160. Perform a table lookup operation according to the temperature of the second-stage three-way catalyst, and look up the fourth maximum oxygen storage capacity corresponding to the temperature of the second-stage three-way catalyst in the second critical aged state three-way catalyst oxygen storage capacity table.

4. The dual-stage three-way catalyst efficiency diagnostic method according to claim 3, characterized in that: S200 specifically includes the following steps: S210. The exhaust flow data is collected by the exhaust flow sensor; S220. Obtain engine speed from ECU via CAN bus; S230. Perform a table lookup operation according to the exhaust flow data and the engine speed, and find the first-stage oxygen storage efficiency coefficient corresponding to the combination of the exhaust flow data and the engine speed in the first-stage three-way catalyst oxygen storage capacity correction table; S240. Perform a table lookup operation according to the exhaust flow data and the engine speed, and find the second-stage oxygen storage efficiency coefficient corresponding to the combination of the exhaust flow data and the engine speed in the second-stage three-way catalyst oxygen storage capacity correction table; S250. Calculate the maximum oxygen storage capacity of the first-stage three-way catalyst after correction, expressed as follows: M′1=M1*η1 Wherein: M′1 is the maximum oxygen storage capacity of the first-stage three-way catalyst after correction; M1 is the first maximum oxygen storage capacity; η1 is the first-stage oxygen storage efficiency coefficient; S260. Calculate the maximum oxygen storage capacity of the first-stage three-way catalyst after correction in the critical state, expressed as follows: M′3=M3*η1 Wherein: M′3 is the critical maximum oxygen storage capacity of the first stage three-way catalyst after correction; M3 is the third maximum oxygen storage capacity; S270. Calculate the maximum oxygen storage capacity of the second-stage three-way catalyst after correction, expressed as follows: M′2=M2*η2 Wherein: M′2 is the maximum oxygen storage capacity of the second-stage three-way catalyst after correction; M2 is the second maximum oxygen storage capacity; η2 is the second-stage oxygen storage efficiency coefficient; S280. Calculate the maximum oxygen storage capacity of the second-stage three-way catalyst after correction in the critical state, expressed as follows: M′4=M4*η2 Wherein: M'4 is the critical maximum oxygen storage capacity of the second-stage three-way catalyst after correction; M4 is the fourth maximum oxygen storage capacity.

5. The dual-stage three-way catalyst efficiency diagnostic method according to claim 4, characterized in that: S300 specifically includes the following steps: S310. Record the total running time after the engine is started; S320. Obtaining the oxygen storage capacity of the first-stage three-way catalyst during the entire operation of the engine; S330. Obtaining the oxygen storage capacity of the second-stage three-way catalyst during the entire operation of the engine; S340. Count the cumulative time that satisfies the condition expressed as follows as the first cumulative time: T1∈T,when(0<M5<M3′) Wherein: T1 is the first accumulated time; T is the total running time after the engine is started; M5 is the oxygen storage capacity of the first stage three-way catalyst during the entire operation of the engine obtained in S320; S350. Count the accumulated time that satisfies the condition expressed as follows as the second accumulated time: T2∈T,when(M3'<M5<(M3'+M1′) / 2) Wherein: T2 is the second accumulated time; S360. Count the accumulated time that satisfies the condition expressed as follows as the third accumulated time: T3∈T,when((M3'+M1′) / 2<M5<M1′) Wherein: T3 is the third accumulated time; S370. Count the accumulated time that satisfies the condition expressed as follows as the fourth accumulated time: T4∈T,when(0<M6<M4′) Wherein: T4 is the fourth accumulated time; M6 is the oxygen storage amount of the second-stage three-way catalyst during the entire operation of the engine obtained in S330; S380. Count the accumulated time that satisfies the condition expressed as follows as the fifth accumulated time: T5∈T,when(M4'<M6<(M4′+M2′) / 2) Wherein: T5 is the fifth accumulated time; S390. Count the accumulated time that satisfies the condition expressed by the following formula as the sixth accumulated time: T6∈T,when((M4'+M2′) / 2<M6<M2′) Wherein: T6 is the sixth accumulated time.

6. The dual-stage three-way catalyst efficiency diagnostic method according to claim 5, characterized in that: S400 specifically includes the following steps: S410. According to the oxygen storage amount of the first-stage three-way catalyst during the entire operation of the engine obtained in S320, the efficiency range is defined for the first-stage three-way catalyst: If (M3′+M1′) / 2<M5<M1′, the first stage three-way catalyst is defined as belonging to the high efficiency range; If M3'<M5<(M3'+M1') / 2, the first stage three-way catalyst is defined as belonging to the general efficiency range; then the second accumulated time is equivalently calculated, specifically expressed as follows: T2′=ε1*T2 Where: T2' is the equivalent second cumulative time; ε1 is the calibrated equivalent parameter, which is preset manually; If 0<M5<M3′, the first stage three-way catalyst is defined as belonging to the low efficiency range; then the first accumulated time is equivalently calculated, specifically expressed as follows: T1′=ε2*T1 Where: T1′ is the equivalent first cumulative time; ε2 is the calibrated equivalent parameter, which is preset manually; S420. According to the oxygen storage amount of the second-stage three-way catalyst during the entire operation of the engine obtained in S330, the efficiency range is defined for the second-stage three-way catalyst: If (M4′+M2′) / 2<M6<M2′, the second-stage three-way catalyst is defined as belonging to the high efficiency range; If M4′<M6<(M4′+M2′) / 2, the second-stage three-way catalyst is defined as belonging to the general efficiency range; then the fifth accumulated time is equivalently calculated, specifically expressed as follows: T5′=ε3*T5 Where: T5' is the equivalent fifth cumulative time; ε3 is the calibrated equivalent parameter, which is preset manually; If 0<M6<M4′, the second stage three-way catalyst is defined as belonging to the low efficiency range; then the fourth accumulated time is equivalently calculated, specifically expressed as follows: T4′=ε4*T4 Wherein: T4′ is the equivalent fourth cumulative time; ε4 is the calibrated equivalent parameter, which is preset manually.

7. The dual-stage three-way catalyst efficiency diagnostic method according to claim 6, characterized in that: The overall efficiency of the two-stage three-way catalyst in S500 is expressed as follows: in: is the overall efficiency of the dual-stage three-way catalyst; γ is the ratio of the coating density of the first-stage three-way catalyst to the coating density of the second-stage three-way catalyst.

8. The dual-stage three-way catalyst efficiency diagnostic method according to claim 7, characterized in that: The dual-stage three-way catalyst efficiency diagnosis process described in S700 specifically includes the following steps: S710. Compare the overall efficiency of the dual-stage three-way catalyst calculated in S500 with the manually preset efficiency calibration limit, and then perform the following operations according to the comparison result: If the overall efficiency of the two-stage three-way catalyst is greater than the efficiency calibration limit, determining that the two-stage three-way catalyst efficiency diagnosis result is that the two-stage three-way catalyst efficiency is normal; If the overall efficiency of the dual-stage three-way catalyst is not greater than the efficiency calibration limit, executing S720; S720. Count the maintenance time of the overall efficiency of the two-stage three-way catalyst being no greater than the efficiency calibration limit; then perform the following operations according to the maintenance time: If the maintenance time during which the overall efficiency of the dual-stage three-way catalyst is not greater than the efficiency calibration limit is less than the manually preset maintenance time threshold, then return to and execute S720 again; If the maintenance time of the dual-stage three-way catalyst overall efficiency being not greater than the efficiency calibration limit is not less than the maintenance time threshold, it is determined that the dual-stage three-way catalyst efficiency diagnosis result is that the dual-stage three-way catalyst efficiency is low.

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