A diagnostic method for the catalytic converter conversion efficiency of a hybrid power system

Abstract

The present invention provides a diagnostic method for the catalytic converter conversion efficiency of a hybrid system, comprising the following steps: S0: The whole vehicle operates in the normal condition A with the normal hybrid strategy, and determines whether the enabling condition is established. If it is established, it enters the diagnostic condition B; S1: After entering the diagnostic condition B, the vehicle controller controls and adjusts the engine operating mode, and determines whether the condition for entering condition B is satisfied. If it is satisfied, it enters the recovery condition C; S2: When entering the recovery condition C, the vehicle controller controls the operating parameters of the engine and determines whether the condition for entering condition C is satisfied. If it is satisfied, it enters step S3; S3: The vehicle controller increments the cycle count by 1, and determines the relationship between the cycle count and the preset threshold. When the cycle count is less than the preset threshold, it returns to step S0 to perform the cycle again; corresponding conditions that meet the detection conditions are designed, so as to effectively diagnose the catalytic converter conversion efficiency of the hybrid system including a single planetary gear set.

Description

Technical Field

[0001] The present invention relates to the technical field of hybrid system control, and particularly to a diagnostic method for the conversion efficiency of a catalytic converter in a hybrid system. Background Art

[0002] The three-way catalytic converter is the most effective way to reduce emissions. If the three-way catalytic converter deteriorates, it will cause an increase in emissions because it no longer plays a catalytic conversion role. The heavy-duty diesel vehicle emission standards require that the efficiency of the catalytic converter must be tested. Among them, the on-board diagnostic system OBD diagnoses the deterioration of the conversion rate of the three-way catalytic converter by means of active testing. Under certain operating conditions, the engine electronic control unit is controlled with a specific air-fuel ratio, and then the conversion efficiency of the three-way catalytic converter is determined by comparing the value of its oxygen storage capacity with the standard value.

[0003] Considering that the engine of the hybrid planetary gear is controlled by the vehicle control unit, and the vehicle is affected by accessories and road environment during actual operation, there are two working modes: frequent engine start-stop and rarely stop. In order to ensure that hybrid planetary gear vehicles meet the detection requirements of the on-board diagnostic system in the emission standards, it is particularly important to seek a method for diagnosing the deterioration of the conversion efficiency of the three-way catalytic converter in the planetary gear hybrid system.

[0004] The prior arts (CN110284947A, CN113236404A, CN113431668A, CN113431669A) have all proposed relevant detection methods, but there is no relevant diagnostic method for the planetary gear hybrid system in the prior arts. Summary of the Invention

[0005] To solve the defects and deficiencies in the above prior arts, the present invention provides a diagnostic method for the conversion efficiency of a catalytic converter in a hybrid system.

[0006] The technical solution recorded in the present invention is as follows:

[0007] A diagnostic method for the conversion efficiency of a catalytic converter in a hybrid system, characterized in that it includes the following steps:

[0008] S0: The vehicle runs in normal operating condition A with a normal hybrid strategy, and determines whether the enabling condition is established. If it is established, it enters the diagnostic condition B;

[0009] S1: After entering the diagnostic condition B, the vehicle control unit controls and adjusts the engine working mode, and determines whether the condition for entering condition B is satisfied. If it is satisfied, it enters the recovery condition C;

[0010] S2: When entering the recovery condition C, the vehicle control unit controls the working parameters of the engine and determines whether the condition for entering condition C is satisfied. If it is satisfied, it enters step S3;

[0011] S3: The vehicle controller increments the control loop count by 1 and determines the relationship between the loop count and the preset threshold. When the loop count is less than the preset threshold, it returns to step S0 to restart the loop. When the loop count reaches the preset threshold C, the loop ends.

[0012] As a further preferred embodiment of the present invention, in step S0, the enabling condition being satisfied includes:

[0013] The engine catalytic converter temperature ≥ T1; and

[0014] The engine coolant temperature ≥ T2; and

[0015] The vehicle requested torque is greater than the braking torque boundary torque and less than the drive motor boundary torque;

[0016] Where T1 and T2 are calibration quantities related to temperature.

[0017] As a further preferred embodiment of the present invention, in step S1, the vehicle controller controls and adjusts the engine operating mode including:

[0018] S1-1: If the engine does not have a start-stop condition, the vehicle controller controls the generator to bring the engine into the reverse drag mode;

[0019] S1-2: If the engine has a frequent start-stop condition and the engine is operating above the idle speed, the vehicle controller controls the engine to enter the stop mode;

[0020] S1-3: If the engine is operating at idle speed due to the need of accessories, the vehicle controller controls the generator to bring the engine into the reverse drag mode to meet the diagnostic requirements.

[0021] As a further preferred embodiment of the present invention, in step S1, the conditions for entering condition B being satisfied include:

[0022] In S1-1: The engine reverse drag speed ≥ n1, the reverse drag torque ≥ Tq1, and the reverse drag operating time ≥ t1;

[0023] In S1-2: The engine stop time ≥ t2;

[0024] In S1-3: The engine reverse drag speed ≥ n1, the reverse drag torque ≥ Tq1, and the reverse drag operating time ≥ t1;

[0025] Where t1 and t2 are calibration quantities related to time, n1 is a calibration quantity related to speed, and Tq1 is a calibration quantity related to torque.

[0026] As a further preferred embodiment of the present invention, in the step S2, the operating parameters of the engine controlled by the vehicle controller include: the operating speed, operating torque, and operating time of the engine.

[0027] As a further preferred embodiment of the present invention, in the step S2, the satisfaction of the condition for entering the operating condition C includes:

[0028] The operating speed of the engine ≥ n2; and

[0029] The operating torque of the engine ≥ Tq2; and

[0030] The operating time of the engine ≥ t2;

[0031] Wherein, t2 is a calibrated quantity related to time, n2 is a calibrated quantity related to speed, and Tq2 is a calibrated quantity related to torque.

[0032] Furthermore, the present invention also provides a diagnostic method for the conversion efficiency of a catalytic converter in a hybrid power system, which is characterized in that it includes the following steps:

[0033] S0: Initialization, set the engine reverse drag mode flag bit to 0, set the reverse drag mode completion flag bit to 0, and set the reverse drag single - time completion flag bit to 0;

[0034] S1: When the ignition switch signal key_on is 1, enter the reverse drag waiting mode. At this time, the engine reverse drag mode flag bit is 0, and the reverse drag single - time completion flag bit is 0;

[0035] S2: Determine whether the condition for entering the reverse drag mode is satisfied. When the condition for entering the reverse drag mode is established, enter the engine reverse drag mode;

[0036] S3: When entering the engine reverse drag state, activate the step counter;

[0037] S4: When the engine is in the reverse drag mode, determine whether the condition for exiting the reverse drag mode is satisfied. When the condition for exiting the reverse drag mode is established, exit the reverse drag mode;

[0038] S5: When exiting the reverse drag mode, if the time < T1, do not count the number of times. If the time > T1, then set the reverse drag single - time completion flag bit + 1. When the cumulative number of times of the reverse drag single - time completion flag bit is more than 8 times, the reverse drag mode completion flag bit is 1;

[0039] Wherein, T1 is the effective reverse drag calibration time;

[0040] S6: Determine whether Key_on is 0. If it is 0, clear the step counter data and transfer to S0;

[0041] If key_on is not 0 and the reverse drag flag bit is not 1, then transfer to S2;

[0042] If key_on is not 0 and the reverse-dragging flag bit is 1, then go to S1.

[0043] As a further preferred embodiment of the present invention, the step S2 includes:

[0044] S2.1: When the engine is in the working state:

[0045] If

[0046] the vehicle speed Veh_spd satisfies V0 < Veh_spd < V1; and

[0047] the vehicle torque Veh_tq satisfies B0 < Veh_tq < B1; and

[0048] both the reverse-dragging mode completion flag bit and the single reverse-dragging completion flag bit are 0, enter the engine reverse-dragging mode;

[0049] S2.2: When the engine is in the shutdown state:

[0050] If

[0051] the vehicle speed Veh_spd satisfies V2 < Veh_spd < V3; and

[0052] the vehicle torque Veh_tq satisfies Veh_tq < B2; and

[0053] both the reverse-dragging mode completion flag bit and the single reverse-dragging completion flag bit are 0, enter the engine reverse-dragging mode;

[0054] Among them,

[0055] V0, V1, V2, V3 are speed-related rotational speed calibration quantities; and V0 < V1 < V2 < V3;

[0056] B0 is the torque boundary obtained by looking up the table through the vehicle speed when considering economy calibration;

[0057] B1, B2 are the drive motor boundary values when considering economy calibration; and B0 < B1 < B2.

[0058] As a further preferred embodiment of the present invention, in the step S4, the condition for exiting the reverse mode is:

[0059] the vehicle torque Veh_tq satisfies Veh_tq > B3;

[0060] or the vehicle torque Veh_tq satisfies Veh_tq < B4;

[0061] or the vehicle speed Veh_spd satisfies Veh_spd < V4;

[0062] Among them,

[0063] V4 is the rotational speed calibration quantity related to the vehicle speed, and V3 < V4;

[0064] B4 is the torque boundary obtained by looking up the table according to the vehicle speed when considering economy calibration;

[0065] B3 is the driving motor boundary value when considering economy calibration, and B2 < B3 < B4.

[0066] A diagnostic method for the conversion efficiency of a catalytic converter in a hybrid power system, characterized in that: in step S5, the reverse-dragging single-completion flag signal is a self-resetting signal, and when the effective time T2 is exceeded, the reverse-dragging single-completion flag returns to 0; wherein, T2 is the self-resetting effective time.

[0067] Compared with the prior art, the technical effects that the present invention can achieve include:

[0068] The present invention provides a diagnostic method for the conversion efficiency of a catalytic converter in a hybrid power system. In the prior art, the vehicle control unit first controls the engine to operate under a rich air-fuel mixture to consume the oxygen stored in the catalytic converter; subsequently, the vehicle control unit forces the catalytic converter to work under a lean air-fuel mixture to store oxygen. The vehicle control unit controls the catalytic converter to work in this controlled air-fuel ratio mode until the oxygen stored in the catalytic converter exceeds a preset calibration value or the post-oxygen sensor indicates that the catalytic converter is completely saturated, and then diagnoses the conversion efficiency of the catalytic converter by comparing the oxygen storage capacity of the catalytic converter with the preset calibration value of the critical catalytic converter. And the present invention designs corresponding working conditions that meet the detection conditions for the above diagnostic method, and controls the system to enter the corresponding working conditions by judging the entry conditions corresponding to each working condition, so as to realize the effective diagnosis of the conversion efficiency of the catalytic converter of the hybrid power system including a single planetary gear set. Description of the Drawings

[0069] Figure 1 It is a schematic structural diagram of the hybrid power system of the present invention;

[0070] Figure 2 It is a schematic diagram of the diagnostic working conditions of the on-board diagnostic system OBD in the first embodiment of the present invention;

[0071] Figure 3 It is a diagnostic working condition operation flow chart of the on-board diagnostic system OBD in the first embodiment of the present invention;

[0072] Figure 4 It is a schematic diagram of each working condition in the second embodiment of the present invention;

[0073] Figure 5 It is a schematic diagram of the state of the engine reverse-dragging mode in the second embodiment of the present invention. Detailed Embodiments

[0074] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention.

[0075] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0076] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "front end", "rear end", "both ends", "one end", "the other end", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0077] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0078] As Figure 1 shown is a schematic structural diagram of a hybrid power system provided by the present invention. It couples an internal combustion engine ICE, a traction motor TM, and a generator ISG together through a planetary gear set G. Among them, the internal combustion engine ICE is connected to the carrier end, the generator ISG is connected to the sun gear end, and the traction motor TM is connected to the ring gear end. Among them, the internal combustion engine ICE is started by being dragged by the generator ISG.

[0079] [First Embodiment]

[0080] In the prior art, the diagnostic method for the catalytic converter conversion efficiency of a planetary gear hybrid power system is as follows:

[0081] 1) First, the vehicle control unit controls the engine to operate under a rich mixture to consume the oxygen stored in the three-way catalytic converter;

[0082] 2) Subsequently, the vehicle controller forces the catalytic converter to store oxygen while operating in a lean mixture. The vehicle controller controls the catalytic converter to operate in this controlled air-fuel ratio mode until the oxygen stored in the catalytic converter exceeds the preset calibration value or the downstream oxygen sensor indicates that the catalytic converter is completely saturated;

[0083] 3) Then, by comparing the oxygen storage capacity of the catalytic converter with the calibration value of the critical catalytic converter, the conversion efficiency of the three-way catalytic converter is diagnosed.

[0084] The purpose of the present invention is to provide a diagnostic method for the conversion efficiency of a catalytic converter in a hybrid power system, designing operating conditions that meet the detection requirements and setting corresponding entry conditions to achieve an effective diagnosis of the conversion efficiency of the catalytic converter. This purpose is achieved through the following technical solutions:

[0085] As Figures 2 - 3 shown in the first embodiment provided by the present invention,

[0086] As Figure 2 shown, this embodiment includes the following three operating conditions: normal condition A (normal operating condition) → diagnostic condition B (engine coast-down or engine message shutdown condition) → recovery condition C (condition where the engine resumes normal operation), specifically:

[0087] Normal condition A:

[0088] When the vehicle is operating normally in normal condition A, after the on-board diagnostic system OBD diagnostic enable condition is satisfied, it enters diagnostic condition B.

[0089] Diagnostic condition B:

[0090] After entering diagnostic condition B, the engine is controlled to enter the shutdown or coast-down mode according to the engine operating mode.

[0091] Recovery condition C:

[0092] After entering recovery condition C, the engine speed and torque are controlled to restore to the normal operating condition, completing a whole diagnostic condition cycle of the on-board diagnostic system OBD.

[0093] As Figure 3 shown, the specific operation steps of the first embodiment are:

[0094] S0: The vehicle operates in normal condition A with a normal hybrid power strategy, and determines whether the enable condition is satisfied. If it is satisfied, it enters diagnostic condition B;

[0095] In this step S0, the satisfaction of the enable condition includes:

[0096] The engine catalytic converter temperature ≥ T1; and

[0097] The engine coolant temperature ≥ T2; and

[0098] The vehicle request torque is greater than the braking torque boundary torque and less than the drive motor boundary torque;

[0099] Where T1 and T2 are calibration quantities related to temperature.

[0100] S1: After entering diagnostic condition B, the vehicle controller controls and adjusts the engine operating mode, and determines whether the conditions of condition B are met. If met, enter the recovery condition C;

[0101] In this step S1, the vehicle controller controls and adjusts the engine operating mode including:

[0102] S1-1: If the engine does not have a start-stop condition, the vehicle controller controls the generator to bring the engine into the reverse drag mode; At this time, the conditions for entering condition B need to be met: the engine reverse drag speed ≥ n1, the reverse drag torque ≥ Tq1, and the reverse drag condition running time ≥ t1;

[0103] S1-2: If the engine has a frequent start-stop condition and the engine is operating above the idle speed, the vehicle controller controls the engine to enter the stop mode; At this time, the conditions for entering condition B need to be met: S1-2: the engine stop time ≥ t2;

[0104] S1-3: If the engine is operating at the idle speed due to the need of accessories, the vehicle controller controls the generator to bring the engine into the reverse drag mode to meet the diagnostic requirements; At this time, the conditions for entering condition B need to be met: the engine reverse drag speed ≥ n1, the reverse drag torque ≥ Tq1, and the reverse drag condition running time ≥ t1;

[0105] Where t1 and t2 are calibration quantities related to time, n1 is a calibration quantity related to speed, and Tq1 is a calibration quantity related to torque.

[0106] S2: When entering the recovery condition C, the vehicle controller controls the engine operating parameters and determines whether the conditions of condition C are met. If met, enter step S3; In this step S2, the vehicle controller controls the engine operating parameters including: the engine operating speed, operating torque, and running time; The conditions for entering condition C being met include:

[0107] The engine operating speed ≥ n2; and

[0108] The engine operating torque ≥ Tq2; and

[0109] The engine running time ≥ t2;

[0110] Where t2 is a calibration quantity related to time, n2 is a calibration quantity related to speed, and Tq2 is a calibration quantity related to torque, where t2 is related to the operating condition speed and torque. The higher the speed and the greater the torque, the smaller t2.

[0111] S3: The vehicle controller increments the control loop count by 1 and determines the relationship between the loop count and the preset threshold. When the loop count is less than the preset threshold, it returns to step S0 to restart the loop. When the loop count reaches the preset threshold C, the loop ends.

[0112] [Second Embodiment]

[0113] As Figures 4 - 5 shown in the second embodiment of the present invention.

[0114] As Figure 4 shown, in the second embodiment of the present invention, according to the actual operating conditions of the vehicle in the single planetary gear hybrid system, a complete diagnostic condition of the catalytic converter conversion efficiency actually includes 5 conditions:

[0115] Condition 1: At the vehicle start stage, the engine is in the shutdown state. When the vehicle speed is higher than the preset value A, and the vehicle requested torque is less than the boundary of the drive motor and greater than the boundary of the braking torque, it enters the reverse drag mode.

[0116] Condition 2: It does not enter the reverse drag mode.

[0117] Condition 3:

[0118] Section A enters the reverse drag mode;

[0119] Section B is in the rapid acceleration state, so it is not in the reverse drag mode;

[0120] Section C enters the reverse drag mode, but the time < T, so it belongs to an invalid reverse drag.

[0121] Section D has a high vehicle speed and is in the reverse drag mode;

[0122] Condition 4: Comprehensively consider the economic calibration and the braking torque boundary B to control whether to enter the reverse drag mode.

[0123] Condition 5: Similar to condition 2, but in condition 5, the vehicle speed is lower than A, so condition 5 cannot enter the reverse drag mode either.

[0124] In this embodiment, the reverse drag module mainly includes three parts: section A corresponds to entering the reverse drag mode, sections B and C correspond to exiting the reverse drag mode, and the effective reverse drag mode corresponds to section D.

[0125] The specific steps of the second embodiment include:

[0126] S0: Initialize, respectively set the engine reverse drag mode flag to 0, the reverse drag mode completion flag to 0, and the reverse drag single - time completion flag to 0;

[0127] S1: When the ignition switch signal key_on is 1, enter the reverse drag waiting mode, the engine reverse drag mode flag bit is 0, and the reverse drag single completion flag bit is 0;

[0128] S2:

[0129] (1)When the engine is in the working state:

[0130] When the vehicle speed Veh_spd of the whole vehicle satisfies V0 < Veh_spd < V1 and the vehicle torque of the whole vehicle satisfies B0 < Veh_tq < B1, and both the reverse drag completion and single completion flag bits are 0, enter the engine reverse drag mode;

[0131] (2)When the engine is in the shutdown state:

[0132] When V2 < the vehicle speed Veh_spd of the whole vehicle < V3 and the vehicle torque Veh_tq < B2, and both the reverse drag completion and single completion flag bits are 0, enter the engine reverse drag mode;

[0133] S3: When entering the engine reverse drag state, activate the step counter;

[0134] S4: When the engine is in the reverse drag mode, when Veh_tq > B3 or Veh_tq < B4 or Veh_spd < V4, exit the reverse drag mode;

[0135] Where

[0136] V0, V1, V2, V3, V4 are speed-related rotational speed calibration values; and satisfy V0 < V1 < V2 < V3 < V4;

[0137] B0, B4 are braking torque boundaries obtained by looking up the table through the vehicle speed after comprehensively considering economic calibration;

[0138] B1, B2, B3 are drive motor boundary values obtained by comprehensively considering economic calibration; and satisfy B0 < B1 < B2 < B3 < B4;

[0139] S5: When exiting the reverse drag mode, if the time is less than T1, the number of times is not counted; if the time > T1, then record the reverse drag single completion flag bit +1 (this signal is a self-resetting signal, and when it exceeds the effective time T2, this signal is automatically reset), when the accumulated number of times is more than 8 times, the reverse drag mode completion flag bit is 1;

[0140] S6: Judge whether Key_on is 0, if it is 0, clear the step counter data, and go to S0;

[0141] If key_on is not 0 and the reverse drag flag bit is not 1, go to S2;

[0142] If key_on is not 0 and the reverse drag flag bit is 1, go to S1.

[0143] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A diagnostic method for the catalytic conversion efficiency of a hybrid power system, characterized in that: It includes the following steps: S0: The whole vehicle operates in normal condition A with a normal hybrid strategy, and determines whether the enabling condition is established. If it is established, it enters the diagnostic condition B; S1: After entering the diagnostic condition B, the vehicle controller controls and adjusts the engine operating mode, and judges whether the condition for entering condition B is satisfied. If it is satisfied, it enters the recovery condition C; S2: When entering the recovery condition C, the vehicle controller controls the engine operating parameters and judges whether the condition for entering condition C is satisfied. If it is satisfied, it enters step S3; S3: The vehicle controller increments the cycle count by 1 and determines the relationship between the cycle count and the preset threshold. When the cycle count is less than the preset threshold, it returns to step S0 to perform the cycle again. When the cycle count reaches the preset threshold C, the cycle ends; In the said step S1, the vehicle controller controls and adjusts the engine operating mode including: S1-1: If the engine does not have a start-stop condition, the vehicle controller controls the generator to bring the engine into the reverse drag mode; S1-2: If the engine has a frequent start-stop condition and the engine is operating above the idle condition, the vehicle controller controls the engine to enter the stop mode; S1-3: If the engine is operating at the idle condition due to the need of accessories, the vehicle controller controls the generator to bring the engine into the reverse drag mode to meet the diagnostic requirements; In the said step S2, the vehicle controller controls the engine operating parameters including: the engine operating speed, operating torque and operating time; In the said step S2, the satisfaction of the condition for entering condition C includes: The engine operating speed ≥ n2; and The engine operating torque ≥ Tq2; and The engine operating time ≥ t2; Wherein, t2 is a calibrated quantity regarding time, n2 is a calibrated quantity regarding speed, and Tq2 is a calibrated quantity regarding torque.

2. The diagnostic method for the catalytic converter conversion efficiency of a hybrid power system according to claim 1, wherein: In the said step S0, the establishment of the enabling condition includes: The engine catalytic converter temperature ≥ T1; and The engine coolant temperature ≥ T2; and The vehicle requested torque is greater than the braking torque boundary torque and less than the drive motor boundary torque; Wherein T1 and T2 are calibrated quantities regarding temperature.

3. A diagnostic method for the conversion efficiency of a catalytic converter in a hybrid power system according to claim 1, characterized in that: In the said step S1, the satisfaction of the condition for entering condition B includes: In S1-1: The engine reverse drag speed ≥ n1, the reverse drag torque ≥ Tq1, and the reverse drag condition operating time ≥ t1; In S1-2: The engine stop time ≥ t2; In S1-3: The engine reverse drag speed ≥ n1, the reverse drag torque ≥ Tq1, and the reverse drag condition operating time ≥ t1; Wherein t1 and t2 are calibrated quantities regarding time, n1 is a calibrated quantity regarding speed, and Tq1 is a calibrated quantity regarding torque.

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