Fault diagnosis method and system for over-standard emission of automobile exhaust

Abstract

The invention discloses a fault diagnosis method and system for over-standard emission of automobile exhaust. The method comprises the steps that pollutant detection data of an exhaust analyzer for oil-generated pollutants and gas-generated pollutants in the automobile exhaust are acquired; determining the fault type of the corresponding automobile as three-way catalysis, mixed gas dilution or mixed gas concentration according to the concentrations of the oil-generated pollutants and the gas-generated pollutants relative to the preset limit values; acquiring engine electric control data, and determining a voltage or current signal of the oxygen sensor and a fuel correction coefficient according to the engine electric control data; and performing consistency diagnosis on the voltage or current signal of the oxygen sensor and the fuel correction coefficient based on the fault type of the automobile, and determining whether the oxygen sensor and the fuel correction coefficient are normal or not. Through the technical scheme of the invention, the fault part of the automobile can be quickly and accurately diagnosed, and the technical problem which puzzles the over-standard emission treatment of the automobile exhaust is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle fault diagnosis, and particularly to a fault diagnosis method for excessive automobile exhaust emissions and a fault diagnosis system for excessive automobile exhaust emissions. Background Art

[0002] In some densely populated cities, mobile sources have become the primary source of pollutant emissions; and the pollutants emitted by a small number of vehicles with excessive exhaust emissions far exceed the total pollutants emitted by normal vehicles. Therefore, making these malfunctioning vehicles with excessive emissions return to a qualified emission state through treatment technology has become the top priority in the prevention and control of air pollution. So, the accurate diagnosis and repair of the causes of excessive motor vehicle exhaust emissions have become an important task that must be faced first. To do this job well, it is necessary to master engine mechanics, electronic control, and chemical knowledge and application skills. However, traditional automotive repair technologies are not competent for the work of exhaust gas treatment, mainly for the following reasons.

[0003] 1. Because traditional automotive repair work is restorative work aimed at functional losses of the vehicle, such as obvious faults like engine stalling, shaking, increased fuel consumption, and malfunction indicator lamp illumination. However, the vast majority of vehicles with excessive exhaust emissions that can enter the environmental protection inspection line often do not have the above fault characteristics. Measured by traditional repair standards, this is an engine without any functional faults. Therefore, it is often difficult to start the diagnosis and repair.

[0004] 2. There are serious misunderstandings in the technical direction of diagnosis. The three main pollutants emitted by automobiles, namely HC (hydrocarbons), CO (carbon monoxide), and NO (nitrogen oxides), are diagnosed and analyzed separately. For each pollutant exceeding the standard, several or even dozens of fault causes are listed. This method not only fails to effectively solve the problem but also results in incorrect repairs and expanded repairs.

[0005] 3. Through long-term work summaries, it is found that the main reasons for excessive automobile exhaust emissions come from two aspects:

[0006] (1) Engine off-board purification devices, such as three-way catalysts, particulate traps, and Scr (selective catalytic reduction) devices.

[0007] (2) Faults in the air-fuel ratio mixture deviation of the engine, such as a rich mixture (more fuel and less air) and a lean mixture (more air and less fuel). Summary of the Invention

[0008] In view of the above problems, the present invention provides a fault diagnosis method and system for excessive automobile exhaust emissions. By combining the pollutant data of the exhaust gas emitted by the automobile engine and the air-fuel mixture data of the engine electronic control system, based on the experience and standards obtained from long-term exhaust gas treatment and fault screening, it can quickly and accurately diagnose the fault location of the automobile according to the excessive automobile exhaust emission data, and solve the problem that has plagued the treatment of excessive automobile exhaust emissions.

[0009] To achieve the above object, the present invention provides a fault diagnosis method for excessive automobile exhaust emissions, including:

[0010] Obtain the pollutant detection data of the exhaust gas analyzer for the oil-borne pollutants and gas-borne pollutants in the automobile exhaust. Among them, the oil-borne pollutants include hydrocarbons, carbon monoxide and smoke density, and the gas-borne pollutants include nitrogen oxides;

[0011] According to whether the concentrations of the oil-borne pollutants and the gas-borne pollutants are higher or lower than the preset limits respectively, determine that the fault type of the corresponding automobile is three-way catalyst, lean air-fuel mixture or rich air-fuel mixture;

[0012] Obtain the engine electronic control data, and determine the voltage or current signal of the oxygen sensor and the fuel correction coefficient according to the engine electronic control data;

[0013] Based on the fault type of the automobile, perform consistency diagnosis on the voltage or current signal of the oxygen sensor and the fuel correction coefficient to determine whether the oxygen sensor and the fuel correction coefficient are normal.

[0014] In the above technical solution, preferably, according to whether the concentrations of the oil-borne pollutants and the gas-borne pollutants are higher or lower than the preset limits respectively, determine that the fault type of the corresponding automobile is three-way catalyst, lean air-fuel mixture or rich air-fuel mixture. The specific process includes:

[0015] Among the oil-borne pollutants, the preset limit of the concentration of hydrocarbons is 10 ppm, the preset limit of carbon monoxide is 0.04%, and the preset limit of smoke density is 0.05. Among the gas-borne pollutants, the preset limit of the concentration of nitrogen oxides is 10 ppm;

[0016] If any of the oil-borne pollutants exceeds the corresponding preset limit, it is determined that there is too much oil, otherwise it is determined that there is too little oil. If the gas-borne pollutant exceeds the corresponding preset limit, it is determined that there is too much gas, otherwise it is determined that there is too little gas;

[0017] If there is too much oil and too much gas, it is determined that the fault type of the automobile is three-way catalyst failure. If there is too little oil but too much gas, it is determined that the fault type of the automobile is lean air-fuel mixture. If there is too much oil but too little gas, it is determined that the fault type of the automobile is rich air-fuel mixture.

[0018] In the above technical solution, preferably, engine electronic control data is obtained, and the voltage or current signal of the oxygen sensor and the fuel correction coefficient are determined according to the engine electronic control data. The specific process includes:

[0019] Obtain the voltage or current signals of the front oxygen sensor and the rear oxygen sensor in the engine electronic control data;

[0020] If the types of the front oxygen sensor and the rear oxygen sensor are switch-type oxygen sensors, determine whether the voltage of the switch-type oxygen sensor is within the normal range. If the voltage is higher than the normal range, it is considered that the fault state of the vehicle is a rich mixture; if the voltage is lower than the normal range, it is considered that the fault state of the vehicle is a lean mixture;

[0021] If the types of the front oxygen sensor and the rear oxygen sensor are wide-band oxygen sensors, determine whether the voltage of the wide-band oxygen sensor is within the normal range. If the voltage is higher than the normal range, it is considered that the fault state of the vehicle is a lean mixture; if the voltage is lower than the normal range, it is considered that the fault state of the vehicle is a rich mixture. Alternatively, determine the current direction of the wide-band oxygen sensor. If the current is a positive current, it is considered that the fault state of the vehicle is a lean mixture; if the current is a negative current, it is considered that the fault state of the vehicle is a rich mixture;

[0022] Obtain the long-term fuel correction coefficient and the short-term fuel correction coefficient in the engine electronic control data. If the long-term fuel correction coefficient or the short-term fuel correction coefficient is positive, it is considered that the vehicle is increasing the fuel injection amount, and the fault state of the vehicle is a lean mixture. If the long-term fuel correction coefficient or the short-term fuel correction coefficient is negative, it is considered that the vehicle is reducing the fuel injection amount, and the fault state of the vehicle is a rich mixture.

[0023] In the above technical solution, preferably, based on the fault type of the vehicle, consistency diagnosis is performed on the voltage or current signal of the oxygen sensor and the fuel correction coefficient to determine whether the oxygen sensor and the fuel correction coefficient are normal. The specific process includes:

[0024] Based on the fault type of the vehicle determined by the pollutant detection data of the vehicle exhaust, if the fault types determined according to the voltage or current data of the front oxygen sensor and the rear oxygen sensor are the same, the front oxygen sensor and the rear oxygen sensor are normal; if they are different, the front oxygen sensor and / or the rear oxygen sensor fails;

[0025] If the fault types determined according to the long-term fuel correction coefficient and the short-term fuel correction coefficient are the same, the long-term fuel correction coefficient and the short-term fuel correction coefficient are correct; if they are different, the long-term fuel correction coefficient and / or the short-term fuel correction coefficient of the engine electronic control data is abnormal.

[0026] In the above technical solution, preferably, the method for diagnosing the failure of excessive emission of automobile exhaust further includes:

[0027] Obtain the air flow meter data of the vehicle, and calculate the normal range of air flow at a preset speed based on the displacement of the vehicle. If the air flow meter data exceeds the normal range of air flow, a large value will cause a rich mixture, and a small value will cause a lean mixture. Then, perform a consistency judgment on the failure type determined by the air flow meter data based on the type of vehicle failure determined by the pollutant detection data of the automobile exhaust. If they are consistent, it is determined that the air flow meter of the vehicle has failed;

[0028] Obtain the intake pressure sensor data of the vehicle. If the intake pressure sensor data exceeds the preset normal range of intake pressure, a large value will cause a rich mixture, and a small value will cause a lean mixture. Then, perform a consistency judgment on the failure type determined by the intake pressure sensor data based on the type of vehicle failure determined by the pollutant detection data of the automobile exhaust. If they are consistent, it is determined that the intake pressure sensor of the vehicle has failed.

[0029] The present invention also proposes a failure diagnosis system for excessive emission of automobile exhaust, which applies the method for diagnosing the failure of excessive emission of automobile exhaust disclosed in any one of the above technical solutions, and includes:

[0030] An exhaust gas data acquisition module, configured to acquire the pollutant detection data of the oil-borne pollutants and gas-borne pollutants in the automobile exhaust by an exhaust gas analyzer, wherein the oil-borne pollutants include hydrocarbons, carbon monoxide and smoke density, and the gas-borne pollutants include nitrogen oxides;

[0031] An exhaust gas failure judgment module, configured to determine the failure type of the corresponding vehicle as three-way catalyst, lean mixture or rich mixture according to whether the concentrations of the oil-borne pollutants and the gas-borne pollutants are higher or lower than the preset limits respectively;

[0032] An electronic control data acquisition module, configured to acquire the engine electronic control data, and determine the voltage or current signal of the oxygen sensor and the fuel correction coefficient according to the engine electronic control data;

[0033] An automobile failure diagnosis module, configured to perform a consistency diagnosis on the voltage or current signal of the oxygen sensor and the fuel correction coefficient based on the failure type of the vehicle, and determine whether the oxygen sensor and the fuel correction coefficient are normal.

[0034] In the above technical solution, preferably, the exhaust gas failure judgment module is specifically configured to:

[0035] If any of the oil-born pollutants exceeds the corresponding preset limit, it is determined that there is too much oil; otherwise, it is determined that there is too little oil. If the air-born pollutants exceed the corresponding preset limit, it is determined that there is too much air; otherwise, it is determined that there is too little air.

[0036] If there is too much oil and too much air, it is determined that the fault type of the vehicle is a three-way catalytic converter fault. If there is too little oil but too much air, it is determined that the fault type of the vehicle is a lean mixture. If there is too much oil but too little air, it is determined that the fault type of the vehicle is a rich mixture.

[0037] Among the oil-born pollutants, the preset concentration limit of hydrocarbons is 10 ppm, the preset limit of carbon monoxide is 0.04%, and the preset limit of smoke density is 0.05. Among the air-born pollutants, the preset concentration limit of nitrogen oxides is 10 ppm.

[0038] In the above technical solution, preferably, the electronic control data acquisition module is specifically configured to:

[0039] Obtain the voltage or current signals of the front oxygen sensor and the rear oxygen sensor in the engine electronic control data.

[0040] If the types of the front oxygen sensor and the rear oxygen sensor are switch-type oxygen sensors, determine whether the voltage of the switch-type oxygen sensor is within the normal range. If the voltage is higher than the normal range, it is considered that the fault state of the vehicle is a rich mixture. If the voltage is lower than the normal range, it is considered that the fault state of the vehicle is a lean mixture.

[0041] If the types of the front oxygen sensor and the rear oxygen sensor are wide-band oxygen sensors, determine whether the voltage of the wide-band oxygen sensor is within the normal range. If the voltage is higher than the normal range, it is considered that the fault state of the vehicle is a lean mixture. If the voltage is lower than the normal range, it is considered that the fault state of the vehicle is a rich mixture. Alternatively, determine the current direction of the wide-band oxygen sensor. If the current is a positive current, it is considered that the fault state of the vehicle is a lean mixture. If the current is a negative current, it is considered that the fault state of the vehicle is a rich mixture.

[0042] Obtain the long-term fuel trim coefficient and the short-term fuel trim coefficient in the engine electronic control data. If the long-term fuel trim coefficient or the short-term fuel trim coefficient is positive, it is considered that the vehicle is increasing the fuel injection amount, and the fault state of the vehicle is a lean mixture. If the long-term fuel trim coefficient or the short-term fuel trim coefficient is negative, it is considered that the vehicle is reducing the fuel injection amount, and the fault state of the vehicle is a rich mixture.

[0043] In the above technical solution, preferably, the vehicle fault diagnosis module is specifically configured to:

[0044] Based on the automobile exhaust pollutant detection data, the automobile fault type is determined. If the fault types determined according to the voltage or current data of the front oxygen sensor and the rear oxygen sensor are consistent, the front oxygen sensor and the rear oxygen sensor are normal; if they are inconsistent, the front oxygen sensor and / or the rear oxygen sensor are faulty;

[0045] If the fault types determined according to the long-term fuel correction coefficient and the short-term fuel correction coefficient are consistent, then the long-term fuel correction coefficient and the short-term fuel correction coefficient are correct; if they are inconsistent, then the long-term fuel correction coefficient and / or the short-term fuel correction coefficient of the engine electronic control data are abnormal.

[0046] In the above technical solution, preferably, the automobile fault diagnosis module is also used for:

[0047] Acquire the air flow meter data of the automobile, and calculate the normal range of air flow at a preset speed based on the displacement of the automobile. If the air flow meter data exceeds the normal range of air flow, a larger value will result in a rich mixed gas, and a smaller value will result in a lean mixed gas. Then, based on the automobile fault type determined by the pollutant detection data of the automobile exhaust, perform consistency judgment on the fault type determined by the air flow meter data, and if they are consistent, determine that the air flow meter of the automobile is faulty;

[0048] The intake pressure sensor data of the vehicle is obtained. If the intake pressure sensor data exceeds a preset normal range of intake pressure, a larger value will result in a rich mixture, while a smaller value will result in a lean mixture. Based on the vehicle fault type determined by the pollutant detection data of the vehicle exhaust, a consistency judgment is made on the fault type determined by the intake pressure sensor data. If they are consistent, it is determined that the intake pressure sensor of the vehicle is faulty.

[0049] Compared with the prior art, the beneficial effects of the present invention are: by combining the exhaust pollutant data of automobile engines and the mixed gas data of the engine electronic control system, based on the experience and standards obtained from long-term exhaust treatment and fault screening, the automobile fault location can be quickly and accurately diagnosed according to the automobile exhaust emission excess data, thus solving the difficult problem that plagues the treatment of automobile exhaust emission excess. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 The present invention is a flowchart of a method for diagnosing excessive exhaust emissions from automobiles disclosed in an embodiment of the present invention. DETAILED DESCRIPTION

[0051] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are only a part rather than all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0052] The present invention will be further described in detail below with reference to the accompanying drawings:

[0053] As Figure 1 shown, a method for diagnosing faults in excessive emissions of automobile exhaust according to the present invention includes:

[0054] Obtaining pollutant detection data of the exhaust gas analyzer for oil-borne pollutants and gas-borne pollutants in the automobile exhaust, wherein the oil-borne pollutants include hydrocarbons, carbon monoxide and smoke density, and the gas-borne pollutants include nitrogen oxides;

[0055] Determining the fault type of the corresponding automobile as three-way catalysis, lean mixture or rich mixture according to whether the concentrations of the oil-borne pollutants and the gas-borne pollutants are higher or lower than the preset limits respectively;

[0056] Obtaining the engine electronic control data, and determining the voltage or current signal of the oxygen sensor and the fuel correction coefficient according to the engine electronic control data;

[0057] Based on the fault type of the automobile, performing consistency diagnosis on the voltage or current signal of the oxygen sensor and the fuel correction coefficient to determine whether the oxygen sensor and the fuel correction coefficient are normal.

[0058] In this embodiment, by combining the exhaust gas pollutant data of the automobile engine and the mixture data of the engine electronic control system, and based on the experience and standards obtained from long-term exhaust gas treatment and fault screening, the fault location of the automobile can be quickly and accurately diagnosed according to the excessive emission data of the automobile exhaust, solving the problem that has plagued the treatment of excessive automobile exhaust emissions.

[0059] Specifically, the exhaust gas pollutants emitted by the engine mainly come from the intake air and fuel of the engine. Among them, the pollutants generated by the fuel are HC hydrocarbons and CO carbon monoxide (smoke density for diesel), and the pollutants generated by the air are NO nitrogen oxides. Therefore, the present invention creatively simplifies the pollutants (HC hydrocarbons, CO carbon monoxide, PM smoke density and NO nitrogen oxides) in the automobile exhaust into the following two types:

[0060] (1) The HC hydrocarbons and CO carbon monoxide generated by gasoline vehicles or the smoke density generated by diesel vehicles are all pollutants generated by the engine fuel, so they are simplified and collectively referred to as oil-borne pollutants (hereinafter referred to as "oil" for short);

[0061] (2) NO nitrogen oxides are pollutants generated by the engine intake air, so they are classified as airborne pollutants (hereinafter referred to as "air").

[0062] In the above embodiment, preferably, according to whether the concentrations of oilborne pollutants and airborne pollutants are respectively higher or lower than the preset limits, determine the fault types of the corresponding vehicle as three-way catalysis, lean mixture or rich mixture. The specific process includes:

[0063] Among the oilborne pollutants, the preset limit for the concentration of hydrocarbons is 10 ppm, the preset limit for carbon monoxide is 0.04%, and the preset limit for smoke density is 0.05. Among the airborne pollutants, the preset limit for the concentration of nitrogen oxides is 10 ppm;

[0064] If any of the oilborne pollutants exceeds the corresponding preset limit, it is determined that there is too much oil, otherwise it is determined that there is too little oil. If the airborne pollutants exceed the corresponding preset limit, it is determined that there is too much air, otherwise it is determined that there is too little air;

[0065] If there is too much oil and too much air, it is determined that the fault type of the vehicle is a three-way catalytic converter fault. If there is too little oil but too much air, it is determined that the fault type of the vehicle is a lean mixture. If there is too much oil but too little air, it is determined that the fault type of the vehicle is a rich mixture.

[0066] According to the above pollutant types, data normalization is performed on their minimum limits. Using the minimum limits as the judgment criteria for determining whether the oil and air exceed the standard emissions, as shown in the following table:

[0067]

[0068] According to this judgment criterion, the present invention creatively simplifies hundreds of fault types derived from traditional technologies into the following three fault types (1. Three-way catalysis, 2. Lean mixture, 3. Rich mixture). By combining the data of oilborne pollutants and airborne pollutants, through the fault judgment examples in the following table, the fault type of vehicle exhaust exceeding the standard and the state of the engine mixture richness can be accurately judged.

[0069]

[0070] In the above embodiment, preferably, obtain the engine electronic control data, and determine the voltage or current signal of the oxygen sensor and the fuel correction coefficient according to the engine electronic control data. The specific process includes:

[0071] Obtain the voltage or current signals of the front oxygen sensor and the rear oxygen sensor in the engine electronic control data;

[0072] If the types of the front oxygen sensor and the rear oxygen sensor are switch-type oxygen sensors, then determine whether the voltage of the switch-type oxygen sensor is within the normal range. If the voltage is higher than the normal range, it is considered that the fault state of the vehicle is a rich air-fuel mixture. If the voltage is lower than the normal range, it is considered that the fault state of the vehicle is a lean air-fuel mixture;

[0073] If the types of the front oxygen sensor and the rear oxygen sensor are wide-band oxygen sensors, then determine whether the voltage of the wide-band oxygen sensor is within the normal range. If the voltage is higher than the normal range, it is considered that the fault state of the vehicle is a lean air-fuel mixture. If the voltage is lower than the normal range, it is considered that the fault state of the vehicle is a rich air-fuel mixture. Or, determine the current direction of the wide-band oxygen sensor. If the current is a positive current, it is considered that the fault state of the vehicle is a lean air-fuel mixture. If the current is a negative current, it is considered that the fault state of the vehicle is a rich air-fuel mixture;

[0074] Obtain the long-term fuel trim coefficient and the short-term fuel trim coefficient in the engine electronic control data. If the long-term fuel trim coefficient or the short-term fuel trim coefficient is positive, it is considered that the vehicle is increasing the fuel injection volume, and the fault state of the vehicle is a lean air-fuel mixture. If the long-term fuel trim coefficient or the short-term fuel trim coefficient is negative, it is considered that the vehicle is reducing the fuel injection volume, and the fault state of the vehicle is a rich air-fuel mixture.

[0075] During the implementation process, the front / rear oxygen sensors and the long / short-term fuel trim programs in the engine electronic control data are high-incidence areas of exhaust gas over-standard faults. However, there has never been a suitable instrument and diagnostic technology to verify whether the signals they feedback are accurate. Therefore, it is impossible to confirm whether they have failed through an accurate technology. In the present invention, the faults in the engine electronic control data are verified according to the fault types judged by the exhaust gas pollutant detection data. If the verification is consistent, it indicates that the corresponding front / rear oxygen sensors and the long / short-term fuel trim programs are normal. If the verification is inconsistent, it indicates that the corresponding front / rear oxygen sensors and / or the long / short-term fuel trim programs are abnormal or faulty.

[0076] For example, the standard data streams and fault types of oxygen sensors of different models disclosed in the following table:

[0077]

[0078] For example, for a switch-type oxygen sensor with a standard data stream of 0.1 V to 0.7 V, the normal voltage range in the normal state of the vehicle is 0.26 V to 0.75 V. When the voltage is 0.65 V, the air-fuel ratio of the engine is in the best state. If the voltage is lower than 0.26 V, it represents that the vehicle is in a lean air-fuel mixture state. If the voltage is higher than 0.75 V, it represents that the vehicle is in a rich air-fuel mixture state.

[0079] For example, for a wide-band oxygen sensor with a standard data stream of 2V±0.05V, if the voltage is lower than 1.95V (2V-0.05V), it means that the vehicle is in a rich mixture state; if the voltage is higher than 2.05V (2V+0.05V), it means that the vehicle is in a lean mixture state. The judgment method for other 2.2V or 3.3V wide-band oxygen sensors is similar.

[0080] In addition, the engine electronic control data has a long / short-term fuel correction coefficient. If the coefficient is in the positive range, it means that the engine computer is controlling to increase the amount of fuel injection. If the coefficient is in the negative range, it means that the engine computer is controlling to reduce the amount of fuel injection.

[0081] In the above implementation, preferably, based on the fault type of the vehicle, the voltage or current signal of the oxygen sensor and the fuel correction factor are diagnosed for consistency to determine whether the oxygen sensor and the fuel correction factor are normal. The specific process includes:

[0082] Based on the automobile exhaust pollutant detection data, the automobile fault type is determined. If the fault types determined according to the voltage or current data of the front oxygen sensor and the rear oxygen sensor are consistent, the front oxygen sensor and the rear oxygen sensor are normal. If they are inconsistent, the front oxygen sensor and / or the rear oxygen sensor are faulty.

[0083] If the fault types determined by the long-term fuel correction factor and the short-term fuel correction factor are consistent, the long-term fuel correction factor and the short-term fuel correction factor are correct. If they are inconsistent, the long-term fuel correction factor and / or short-term fuel correction factor of the engine electronic control data are abnormal.

[0084] In the above implementation, preferably, the fault diagnosis method for excessive exhaust emissions from automobiles also includes:

[0085] The air flow meter data of the vehicle is obtained, and the normal range of air flow at a preset speed is calculated based on the displacement of the vehicle. If the air flow meter data exceeds the normal range of air flow, a large value will result in a rich mixture, and a small value will result in a lean mixture. Based on the vehicle fault type determined by the pollutant detection data of the vehicle exhaust, the fault type determined by the air flow meter data is judged for consistency. If they are consistent, it is determined that the vehicle's air flow meter has a fault.

[0086] During the implementation process, the standard data stream of the air flow rate is the engine displacement × coefficient 1 to 1.3 (g / s) when the engine speed is 700 revolutions per minute. For example, for a 2.0-liter displacement engine with a speed of 700 revolutions per minute, the air flow rate between 2.0 and 2.6 g / s is the normal state. If it is greater than 2.6 g / s, it is determined that the air-fuel mixture is rich. If the type of vehicle fault determined based on the pollutant detection data of the vehicle exhaust is also rich air-fuel mixture, it is determined that the air flow meter is faulty. If the air flow rate is less than 2.0 g / s, it is determined that the air-fuel mixture is lean. If the type of vehicle fault determined based on the pollutant detection data of the vehicle exhaust is also lean air-fuel mixture, it is determined that the vehicle's air flow meter is faulty.

[0087] Obtain the intake pressure sensor data of the vehicle. If the intake pressure sensor data exceeds the preset normal range of the intake pressure, a large value will cause the air-fuel mixture to be rich, and a small value will cause the air-fuel mixture to be lean. Then, make a consistency judgment on the fault type determined by the intake pressure sensor data based on the type of vehicle fault determined by the pollutant detection data of the vehicle exhaust. If they are consistent, it is determined that the vehicle's intake pressure sensor is faulty.

[0088] During the implementation process, under the stable idle condition of the engine, the normal range of the intake pressure of the intake pressure sensor is 28 ± 7 kPa, that is, the intake pressure between (21 - 35 kPa) is normal. If it is greater than 35 kPa, it will cause the air-fuel mixture to be rich. If the type of vehicle fault determined based on the pollutant detection data of the vehicle exhaust is also rich air-fuel mixture, it is determined that the intake pressure sensor is faulty. If it is less than 21 kPa, it will cause the air-fuel mixture to be lean. If the type of vehicle fault determined based on the pollutant detection data of the vehicle exhaust is also lean air-fuel mixture, it is determined that the vehicle's intake pressure sensor is faulty.

[0089] According to the vehicle exhaust emission exceedance fault diagnosis method disclosed in the above implementation manner, taking a 2.0-liter displacement engine as an example, with a speed of 700 revolutions, and a switching type oxygen sensor before and after. According to the exhaust data, taking the following table as an example, the diagnosis results of the fault location by this diagnosis method are described by ticking the fault location in the blanks behind normal and wrong.

[0090]

[0091]

[0092]

[0093] The present invention also proposes a vehicle exhaust emission exceedance fault diagnosis system, which applies the vehicle exhaust emission exceedance fault diagnosis method disclosed in any one of the above implementation manners, including:

[0094] An exhaust gas data acquisition module, which is used to acquire the pollutant detection data of the exhaust gas analyzer for the oil-born pollutants and gas-born pollutants in the vehicle exhaust. Among them, the oil-born pollutants include hydrocarbons, carbon monoxide and smoke density, and the gas-born pollutants include nitrogen oxides;

[0095] An exhaust gas fault judgment module, which is used to determine the fault type of the corresponding vehicle as three-way catalytic, lean mixture or rich mixture according to whether the concentrations of the oil-born pollutants and gas-born pollutants are higher or lower than the preset limits respectively;

[0096] An engine control data acquisition module, which is used to acquire the engine control data and determine the voltage or current signal of the oxygen sensor and the fuel correction coefficient according to the engine control data;

[0097] A vehicle fault diagnosis module, which is used to perform a consistency diagnosis on the voltage or current signal of the oxygen sensor and the fuel correction coefficient based on the fault type of the vehicle to determine whether the oxygen sensor and the fuel correction coefficient are normal.

[0098] In the above embodiment, preferably, the exhaust gas fault judgment module is specifically used for:

[0099] If any of the oil-born pollutants exceeds the corresponding preset limit, it is determined that there is too much oil, otherwise it is determined that there is too little oil. If the gas-born pollutant exceeds the corresponding preset limit, it is determined that there is too much gas, otherwise it is determined that there is too little gas;

[0100] If there is too much oil and too much gas, it is determined that the fault type of the vehicle is three-way catalytic converter fault. If there is too little oil but too much gas, it is determined that the fault type of the vehicle is lean mixture. If there is too much oil but too little gas, it is determined that the fault type of the vehicle is rich mixture;

[0101] Among them, for the oil-born pollutants, the preset limit of the concentration of hydrocarbons is 10 ppm, the preset limit of carbon monoxide is 0.04%, and the preset limit of smoke density is 0.05. For the gas-born pollutants, the preset limit of the concentration of nitrogen oxides is 10 ppm.

[0102] In the above embodiment, preferably, the engine control data acquisition module is specifically used for:

[0103] Acquire the voltage or current signals of the front oxygen sensor and the rear oxygen sensor in the engine control data;

[0104] If the types of the front oxygen sensor and the rear oxygen sensor are switch-type oxygen sensors, judge whether the voltage of the switch-type oxygen sensor is within the normal range. If the voltage is higher than the normal range, it is considered that the fault state of the vehicle is rich mixture. If the voltage is lower than the normal range, it is considered that the fault state of the vehicle is lean mixture;

[0105] If the types of the front oxygen sensor and the rear oxygen sensor are wide-band oxygen sensors, determine whether the voltage of the wide-band oxygen sensor is within the normal range. If the voltage is higher than the normal range, it is considered that the fault state of the vehicle is a lean mixture; if the voltage is lower than the normal range, it is considered that the fault state of the vehicle is a rich mixture. Alternatively, determine the current direction of the wide-band oxygen sensor. If the current is a positive current, it is considered that the fault state of the vehicle is a lean mixture; if the current is a negative current, it is considered that the fault state of the vehicle is a rich mixture.

[0106] Obtain the long-term fuel trim coefficient and the short-term fuel trim coefficient in the engine electronic control data. If the long-term fuel trim coefficient or the short-term fuel trim coefficient is positive, it is considered that the vehicle is increasing the fuel injection amount, and the fault state of the vehicle is a lean mixture. If the long-term fuel trim coefficient or the short-term fuel trim coefficient is negative, it is considered that the vehicle is reducing the fuel injection amount, and the fault state of the vehicle is a rich mixture.

[0107] In the above embodiment, preferably, the vehicle fault diagnosis module is specifically configured to:

[0108] Based on the vehicle fault type determined from the pollutant detection data of the vehicle exhaust, if the fault types determined according to the voltage or current data of the front oxygen sensor and the rear oxygen sensor are the same, the front oxygen sensor and the rear oxygen sensor are normal; if they are different, the front oxygen sensor and / or the rear oxygen sensor fails.

[0109] If the fault types determined according to the long-term fuel trim coefficient and the short-term fuel trim coefficient are the same, the long-term fuel trim coefficient and the short-term fuel trim coefficient are correct; if they are different, the long-term fuel trim coefficient and / or the short-term fuel trim coefficient of the engine electronic control data is abnormal.

[0110] In the above embodiment, preferably, the vehicle fault diagnosis module is further configured to:

[0111] Obtain the air flow meter data of the vehicle, and calculate the normal range of the air flow at the preset speed based on the displacement of the vehicle. If the air flow meter data exceeds the normal range of the air flow, a large value will cause a rich mixture, and a small value will cause a lean mixture. Then, perform a consistency judgment on the fault type determined by the air flow meter data based on the vehicle fault type determined from the pollutant detection data of the vehicle exhaust. If they are the same, it is determined that the air flow meter of the vehicle fails.

[0112] Obtain the intake pressure sensor data of the vehicle. If the intake pressure sensor data exceeds the preset normal range of the intake pressure, a large value will cause a rich mixture, and a small value will cause a lean mixture. Then, perform a consistency judgment on the fault type determined by the intake pressure sensor data based on the vehicle fault type determined from the pollutant detection data of the vehicle exhaust. If they are the same, it is determined that the intake pressure sensor of the vehicle fails.

[0113] For the fault diagnosis system for excessive emission of vehicle exhaust disclosed according to the above embodiments, the functions to be achieved by each module respectively correspond to the steps of the fault diagnosis method for excessive emission of vehicle exhaust disclosed in the above embodiments. During the implementation process, refer to the above embodiments for operation, and details are not described herein again.

[0114] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, 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 fault diagnosis method for excessive exhaust emissions from automobiles, characterized in that: include: Acquire pollutant detection data of the exhaust gas analyzer for oil-borne pollutants and gas-borne pollutants in automobile exhaust, wherein the oil-borne pollutants include hydrocarbons, carbon monoxide and smoke, and the gas-borne pollutants include nitrogen oxides; According to the concentrations of the oil-borne pollutants and the gas-borne pollutants relative to preset limit values, respectively, determining the fault type of the corresponding vehicle as three-way catalytic converter, lean mixture or rich mixture; Acquiring engine electronic control data, and determining a voltage or current signal of an oxygen sensor and a fuel correction factor according to the engine electronic control data; Based on the fault type of the automobile, a consistency diagnosis is performed on the voltage or current signal of the oxygen sensor and the fuel correction factor to determine whether the oxygen sensor and the fuel correction factor are normal.

2. The fault diagnosis method for excessive exhaust emissions of automobiles according to claim 1 is characterized in that: According to the concentrations of the oil-borne pollutants and the gas-borne pollutants relative to the preset limit values, respectively, determining the fault type of the corresponding vehicle as three-way catalytic converter, lean mixture or rich mixture, the specific process includes: Among the oil-borne pollutants, the preset limit value of hydrocarbon concentration is 10ppm, the preset limit value of carbon monoxide is 0.04%, the preset limit value of smoke density is 0.05, and among the gas-borne pollutants, the preset limit value of nitrogen oxide concentration is 10ppm; If any of the oil-borne pollutants exceeds the corresponding preset limit, it is determined that there is too much oil, otherwise it is determined that there is too little oil; if the gas-borne pollutants exceed the corresponding preset limit, it is determined that there is too much gas, otherwise it is determined that there is too little gas; If there is more oil and more gas, the fault type of the car is determined to be a three-way catalytic converter fault. If there is less oil but more gas, the fault type of the car is determined to be a lean mixture. If there is more oil but less gas, the fault type of the car is determined to be a rich mixture.

3. The fault diagnosis method for excessive exhaust emissions of automobiles according to claim 2, characterized in that: The engine electronic control data is obtained, and the voltage or current signal of the oxygen sensor and the fuel correction factor are determined according to the engine electronic control data. The specific process includes: Obtain the voltage or current signal of the front oxygen sensor and the rear oxygen sensor in the engine electronic control data; If the front oxygen sensor and the rear oxygen sensor are switch-type oxygen sensors, it is determined whether the voltage of the switch-type oxygen sensor is within a normal range, if the voltage is higher than the normal range, it is considered that the fault state of the vehicle is a rich mixture, and if the voltage is lower than the normal range, it is considered that the fault state of the vehicle is a lean mixture; If the front oxygen sensor and the rear oxygen sensor are broadband oxygen sensors, then judging whether the voltage of the broadband oxygen sensor is within a normal range, if the voltage is higher than the normal range, it is considered that the fault state of the vehicle is a lean mixture, and if the voltage is lower than the normal range, it is considered that the fault state of the vehicle is a rich mixture, or judging the current direction of the broadband oxygen sensor, if the current is a positive current, it is considered that the fault state of the vehicle is a lean mixture, and if the current is a negative current, it is considered that the fault state of the vehicle is a rich mixture; A long-term fuel correction coefficient and a short-term fuel correction coefficient are obtained from the electronic control data of the engine. If the long-term fuel correction coefficient or the short-term fuel correction coefficient is positive, it is considered that the vehicle is increasing the fuel injection amount, and the fault state of the vehicle is a lean mixture. If the long-term fuel correction coefficient or the short-term fuel correction coefficient is negative, it is considered that the vehicle is reducing the fuel injection amount, and the fault state of the vehicle is a rich mixture.

4. The fault diagnosis method for excessive exhaust emissions from automobiles according to claim 3 is characterized in that: Based on the fault type of the automobile, consistency diagnosis is performed on the voltage or current signal of the oxygen sensor and the fuel correction factor to determine whether the oxygen sensor and the fuel correction factor are normal. The specific process includes: Based on the automobile exhaust pollutant detection data, the automobile fault type is determined. If the fault types determined according to the voltage or current data of the front oxygen sensor and the rear oxygen sensor are consistent, the front oxygen sensor and the rear oxygen sensor are normal; if they are inconsistent, the front oxygen sensor and / or the rear oxygen sensor are faulty; If the fault types determined according to the long-term fuel correction coefficient and the short-term fuel correction coefficient are consistent, then the long-term fuel correction coefficient and the short-term fuel correction coefficient are correct; if they are inconsistent, then the long-term fuel correction coefficient and / or the short-term fuel correction coefficient of the engine electronic control data are abnormal.

5. The fault diagnosis method for excessive exhaust emissions from automobiles according to claim 4 is characterized in that: Also includes: Acquire the air flow meter data of the automobile, and calculate the normal range of air flow at a preset speed based on the displacement of the automobile. If the air flow meter data exceeds the normal range of air flow, a larger value will result in a rich mixed gas, and a smaller value will result in a lean mixed gas. Then, based on the automobile fault type determined by the pollutant detection data of the automobile exhaust, perform consistency judgment on the fault type determined by the air flow meter data, and if they are consistent, determine that the air flow meter of the automobile is faulty; The intake pressure sensor data of the vehicle is obtained. If the intake pressure sensor data exceeds a preset normal range of intake pressure, a larger value will result in a rich mixture, while a smaller value will result in a lean mixture. Based on the vehicle fault type determined by the pollutant detection data of the vehicle exhaust, a consistency judgment is made on the fault type determined by the intake pressure sensor data. If they are consistent, it is determined that the intake pressure sensor of the vehicle is faulty.

6. A fault diagnosis system for excessive exhaust emissions from automobiles, characterized in that: The fault diagnosis method for excessive exhaust emissions of automobiles according to any one of claims 1 to 5 comprises: An exhaust data acquisition module is used to acquire pollutant detection data of the exhaust analyzer for oil-borne pollutants and gas-borne pollutants in automobile exhaust, wherein the oil-borne pollutants include hydrocarbons, carbon monoxide and smoke, and the gas-borne pollutants include nitrogen oxides; An exhaust fault judgment module is used to determine the fault type of the corresponding vehicle as three-way catalytic converter, lean mixture or rich mixture according to the concentration of the oil-borne pollutants and the gas-borne pollutants relative to the preset limit values; An electronic control data acquisition module, used to acquire electronic control data of the engine, and determine a voltage or current signal of the oxygen sensor and a fuel correction factor according to the electronic control data of the engine; The vehicle fault diagnosis module is used to perform consistency diagnosis on the voltage or current signal of the oxygen sensor and the fuel correction factor based on the fault type of the vehicle, and determine whether the oxygen sensor and the fuel correction factor are normal.

7. The fault diagnosis system for excessive exhaust emissions of automobiles according to claim 6, characterized in that: The exhaust gas fault judgment module is specifically used for: If any of the oil-borne pollutants exceeds the corresponding preset limit, it is determined that there is too much oil, otherwise it is determined that there is too little oil; if the gas-borne pollutants exceed the corresponding preset limit, it is determined that there is too much gas, otherwise it is determined that there is too little gas; If there is more oil and more gas, the fault type of the automobile is determined to be a three-way catalytic converter fault; if there is less oil but more gas, the fault type of the automobile is determined to be a lean mixture; if there is more oil but less gas, the fault type of the automobile is determined to be a rich mixture; Among them, among the oil-borne pollutants, the preset limit value of hydrocarbon concentration is 10ppm, the preset limit value of carbon monoxide is 0.04%, the preset limit value of smoke density is 0.05, and among the gas-borne pollutants, the preset limit value of nitrogen oxide concentration is 10ppm.

8. The fault diagnosis system for excessive exhaust emissions of automobiles according to claim 7, characterized in that: The electronic control data acquisition module is specifically used for: Obtain the voltage or current signal of the front oxygen sensor and the rear oxygen sensor in the engine electronic control data; If the front oxygen sensor and the rear oxygen sensor are switch-type oxygen sensors, it is determined whether the voltage of the switch-type oxygen sensor is within a normal range, if the voltage is higher than the normal range, it is considered that the fault state of the vehicle is a rich mixture, and if the voltage is lower than the normal range, it is considered that the fault state of the vehicle is a lean mixture; If the front oxygen sensor and the rear oxygen sensor are broadband oxygen sensors, then judging whether the voltage of the broadband oxygen sensor is within a normal range, if the voltage is higher than the normal range, it is considered that the fault state of the vehicle is a lean mixture, and if the voltage is lower than the normal range, it is considered that the fault state of the vehicle is a rich mixture, or judging the current direction of the broadband oxygen sensor, if the current is a positive current, it is considered that the fault state of the vehicle is a lean mixture, and if the current is a negative current, it is considered that the fault state of the vehicle is a rich mixture; A long-term fuel correction coefficient and a short-term fuel correction coefficient are obtained from the electronic control data of the engine. If the long-term fuel correction coefficient or the short-term fuel correction coefficient is positive, it is considered that the vehicle is increasing the fuel injection amount, and the fault state of the vehicle is a lean mixture. If the long-term fuel correction coefficient or the short-term fuel correction coefficient is negative, it is considered that the vehicle is reducing the fuel injection amount, and the fault state of the vehicle is a rich mixture.

9. The fault diagnosis system for excessive exhaust emissions of automobiles according to claim 8, characterized in that: The automobile fault diagnosis module is specifically used for: Based on the automobile exhaust pollutant detection data, the automobile fault type is determined. If the fault types determined according to the voltage or current data of the front oxygen sensor and the rear oxygen sensor are consistent, the front oxygen sensor and the rear oxygen sensor are normal; if they are inconsistent, the front oxygen sensor and / or the rear oxygen sensor are faulty; If the fault types determined according to the long-term fuel correction coefficient and the short-term fuel correction coefficient are consistent, then the long-term fuel correction coefficient and the short-term fuel correction coefficient are correct; if they are inconsistent, then the long-term fuel correction coefficient and / or the short-term fuel correction coefficient of the engine electronic control data are abnormal.

10. The fault diagnosis system for excessive exhaust emissions of automobiles according to claim 9, characterized in that: The automobile fault diagnosis module is also used for: Acquire the air flow meter data of the automobile, and calculate the normal range of air flow at a preset speed based on the displacement of the automobile. If the air flow meter data exceeds the normal range of air flow, a larger value will result in a rich mixed gas, and a smaller value will result in a lean mixed gas. Then, based on the automobile fault type determined by the pollutant detection data of the automobile exhaust, perform consistency judgment on the fault type determined by the air flow meter data, and if they are consistent, determine that the air flow meter of the automobile is faulty; The intake pressure sensor data of the vehicle is obtained. If the intake pressure sensor data exceeds a preset normal range of intake pressure, a larger value will result in a rich mixture, while a smaller value will result in a lean mixture. Based on the vehicle fault type determined by the pollutant detection data of the vehicle exhaust, a consistency judgment is made on the fault type determined by the intake pressure sensor data. If they are consistent, it is determined that the intake pressure sensor of the vehicle is faulty.

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