A fault diagnosis method and device of a urea system, the urea system and a vehicle

Abstract

The application provides a urea system fault diagnosis method and device, a urea system and a vehicle, and belongs to the technical field of vehicles, aiming to detect the faulty element in the urea system by connecting the urea system with the outside world in the case of abnormal pressure of the urea system, and improve the maintenance efficiency; the urea system comprises a pressure sensor, the method comprises the following steps: in response to the power-on of the vehicle, acquiring a first pressure value collected by the pressure sensor and an environmental pressure value of the environment in which the vehicle is located; based on the first pressure value and the environmental pressure value, performing pressure anomaly detection on the urea system; in the case of pressure anomaly, controlling the urea system to exchange gas with the outside environment, and acquiring a second pressure value collected by the pressure sensor in the gas exchange process; based on the second pressure value and the environmental pressure value, performing pressure anomaly detection on the urea system; based on the result of the pressure anomaly detection, determining the faulty element from a plurality of elements contained in the urea system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vehicles, in particular to a fault diagnosis method and device of a urea system, a urea system and a vehicle. BACKGROUND

[0002] The control unit of the current urea system of a vehicle generally judges whether the system pressure is normal through the data collected by the pressure sensor in the urea system.

[0003] However, the current method of directly collecting data through the pressure sensor to judge whether the system is normal does not take into account the influence of pressure sensor failure, so that if the urea system fails, the real cause of the failure cannot be determined, which makes the maintenance time-consuming and laborious, and even leads to false alarms, resulting in ineffective maintenance of urea system failure. SUMMARY

[0004] Therefore, the present application aims to provide a fault diagnosis method and device of a urea system, a urea system and a vehicle to solve the problem that the current fault diagnosis method of the urea system cannot determine the real cause of the failure, resulting in time-consuming and laborious maintenance.

[0005] To achieve the above-mentioned purpose, the technical solution of the present application is as follows:

[0006] A fault diagnosis method of a urea system, the urea system comprising a pressure sensor for detecting the internal pressure of the urea system, the method comprising:

[0007] In response to the vehicle being powered on, acquiring a first pressure value collected by the pressure sensor and an environmental pressure value of the environment in which the vehicle is located;

[0008] Based on the first pressure value and the environmental pressure value, performing pressure anomaly detection on the urea system, the pressure anomaly detection being used to determine whether the urea system has a pressure anomaly;

[0009] In the case where the pressure anomaly exists, controlling the urea system to exchange gas with the external environment, so as to equalize the gas pressure between the urea system and the external environment through the gas exchange, and acquiring a second pressure value collected by the pressure sensor during the gas exchange;

[0010] Based on the second pressure value and the environmental pressure value, performing the pressure anomaly detection on the urea system;

[0011] Based on the result of the pressure anomaly detection, determining the element of the urea system that has a fault from a plurality of elements included in the urea system.

[0012] Further, the urea system comprises a urea tank, and a breather valve arranged on the urea tank, the breather valve being used to adjust the internal pressure of the urea system, and based on the result of the pressure abnormality detection, determining the element of the urea system that is faulty from a plurality of elements included in the urea system, comprising:

[0013] In the case that the result of the pressure abnormality detection is that the pressure is normal, determining that the faulty element is the breather valve;

[0014] In the case that the result of the pressure abnormality detection is that the pressure is abnormal, determining that the faulty element is the pressure sensor.

[0015] Further, a plurality of the second pressure values are included, the plurality of the second pressure values being obtained in chronological order during the gas exchange process; and the pressure abnormality detection is performed on the urea system based on the second pressure values and the ambient pressure value, comprising:

[0016] Based on the plurality of the second pressure values, determining the pressure change trend of the urea system during the gas exchange process;

[0017] Determining a first pressure difference between each of the second pressure values and the ambient pressure value, to obtain a plurality of the first pressure differences;

[0018] Based on the plurality of the first pressure differences and the pressure change trend, determining whether the urea system still has pressure abnormality.

[0019] Further, based on the plurality of the first pressure differences and the pressure change trend, determining whether the urea system still has pressure abnormality, comprising:

[0020] Based on the pressure change trend, determining a target pressure difference from the plurality of the first pressure differences; wherein the target pressure difference is a first pressure difference corresponding to a second pressure value at a flat stage of the pressure change trend;

[0021] In the case that the target pressure difference is within a preset difference value range and the pressure change trend is a preset trend, determining that the pressure of the urea system is normal;

[0022] In the case that the target pressure difference is not within the preset difference value range and / or the pressure change trend is not the preset trend, determining that the pressure of the urea system is abnormal; wherein the preset difference value range is a normal pressure difference value range between the urea system and the environment in which the urea system is located when the urea system is not started.

[0023] Further, the pressure abnormality detection performed on the urea system based on the second pressure values and the ambient pressure value, comprising:

[0024] determining a second pressure difference between the second pressure value and the ambient pressure value;

[0025] in a case where the second pressure difference is not within a preset difference value range, re-acquiring the second pressure value and re-determining the second pressure difference between the second pressure value and the ambient pressure value;

[0026] in a case where the number of times of re-acquiring the second pressure value reaches a preset number of times and the second pressure difference corresponding to the second pressure value acquired at the last time is still not within the preset difference value range, determining that the urea system pressure is abnormal; wherein the preset difference value range is a normal pressure difference value range between the urea system and the environment in which the urea system is not started.

[0027] Further, the urea system comprises an injector and a delivery pipe connected to the injector, and the injector adjusts the communication or disconnection between the urea system and the exhaust pipeline of the vehicle; before the control of the gas exchange between the urea system and the external environment, the method further comprises:

[0028] controlling the urea system to communicate with the exhaust pipeline, so that the residual urea in the delivery pipe is injected into the exhaust pipeline;

[0029] in the communication process, acquiring a third pressure value collected by the pressure sensor;

[0030] based on the third pressure value and the ambient pressure value, performing the pressure abnormality detection on the urea system to determine whether the urea system still has a pressure abnormality;

[0031] the control of the gas exchange between the urea system and the external environment comprises:

[0032] in a case where the pressure abnormality detection on the urea system determines that the urea system still has an abnormality, controlling the gas exchange between the urea system and the external environment.

[0033] Further, the pressure abnormality detection on the urea system comprises:

[0034] determining a third pressure difference between the pressure value currently detected by the pressure sensor and the ambient pressure value;

[0035] in a case where the third pressure difference is within the preset difference value range, determining that the urea system pressure is normal;

[0036] in a case where the third pressure difference is not within the preset difference value range, determining that the urea system pressure is abnormal.

[0037] Compared with the prior art, the fault diagnosis method of the urea system has the following advantages:

[0038] The fault diagnosis method of the urea system provided by the application comprises the following steps: in response to the vehicle being powered on, acquiring a first pressure value collected by a pressure sensor and an ambient pressure value of an environment in which the vehicle is located; performing pressure anomaly detection on the urea system based on the first pressure value and the ambient pressure value, the pressure anomaly detection being used to determine whether the urea system has a pressure anomaly; in the case where the pressure anomaly exists, controlling the urea system to exchange gas with the external environment, so as to equalize the gas pressure between the urea system and the external environment through the gas exchange, and acquiring a second pressure value collected by the pressure sensor during the gas exchange; performing the pressure anomaly detection on the urea system based on the second pressure value and the ambient pressure value; and based on the result of the pressure anomaly detection, determining, from a plurality of elements included in the urea system, an element of the urea system that has a fault.

[0039] Therefore, according to the application, when the vehicle is powered on, whether the urea system has a pressure anomaly is determined according to the pressure sensor data in the urea system, and when the pressure anomaly exists, the urea system is connected to the environment, and after the urea system is connected to the environment, the urea system exchanges gas with the environment, so that the pressure of the urea system gradually becomes consistent with the ambient pressure. Therefore, after the urea system is connected to the environment, the element of the urea system that has a fault is determined according to the ambient pressure value and the pressure value collected by the pressure sensor, that is, whether the problem is that the data collected by the pressure sensor itself is incorrect or the problem is that the element of the urea system itself is incorrect. Since the cause of the pressure anomaly of the urea system can be determined, the element of the urea system that has a fault can be accurately located, and the element that has a fault can be repaired, thereby avoiding the problem that the cause of the fault needs to be determined again before the repair, which is time-consuming and laborious.

[0040] Another object of the application is to provide a fault diagnosis device for a urea system, so as to solve the problem that the current fault judgment method for the urea system cannot determine the real cause of the fault, resulting in time-consuming and laborious repair.

[0041] To achieve the above object, the technical scheme of the application is as follows:

[0042] A fault diagnosis device for a urea system, the urea system comprising a pressure sensor used to detect the internal pressure of the urea system, the device comprising:

[0043] An acquisition module is configured to acquire a first pressure value collected by the pressure sensor and an ambient pressure value of an environment in which the vehicle is located in response to power-on of the vehicle;

[0044] A first execution module is configured to perform pressure anomaly detection on the urea system based on the first pressure value and the ambient pressure value, and the pressure anomaly detection is configured to determine whether the urea system has a pressure anomaly;

[0045] A control module is configured to control the urea system to exchange gas with an external environment to balance the air pressure between the urea system and the external environment through the gas exchange, and to acquire a second pressure value collected by the pressure sensor during the gas exchange in the case where the pressure anomaly exists;

[0046] A second execution module is configured to perform the pressure anomaly detection on the urea system based on the second pressure value and the ambient pressure value;

[0047] A determination module is configured to determine an element of the urea system that has a fault based on a result of the pressure anomaly detection from a plurality of elements included in the urea system.

[0048] The fault diagnosis device of the urea system and the fault diagnosis method of the urea system have the same advantages as the prior art, and thus are not described herein.

[0049] Another object of the present application is to provide a urea system to solve the problem that the current fault judgment method of the urea system cannot determine the real cause of the fault, resulting in time-consuming and laborious maintenance.

[0050] To achieve the above object, the technical solution of the present application is as follows:

[0051] A urea system, which is in communication connection with a urea control unit, and the urea control unit is configured to perform the fault diagnosis method of the urea system;

[0052] The urea system comprises a pressure sensor and a filling pipe provided with a sealing cap.

[0053] The pressure sensor is configured to detect the internal pressure of the urea system.

[0054] The filling pipe is in communication with the interior of the urea system, and the filling pipe is configured to inject urea into the urea system; wherein the sealing cap is provided with a cover plate having an electrically controlled switch, the cover plate is configured to adjust the communication or disconnection between the urea system and the external environment, and the electrically controlled switch is controlled by the urea control unit.

[0055] The urea system has the same advantages as the urea system fault diagnosis method of the prior art, and details are not repeated here.

[0056] Another object of the present application is to provide a vehicle to solve the problem that the current urea system fault diagnosis method cannot determine the real cause of the fault, resulting in time-consuming and laborious maintenance.

[0057] To achieve the above object, the technical scheme of the present application is as follows:

[0058] A vehicle comprising: a fault diagnosis unit for executing the urea system fault diagnosis method described above.

[0059] The vehicle has the same advantages as the urea system fault diagnosis method of the prior art, and details are not repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0060] The accompanying drawings, which form a part of the present application, are intended to provide further understanding of the present application, and the illustrative embodiments of the present application and their description serve the purpose of explaining the present application. The present application is not limited by the improper limitations. In the drawings:

[0061] Figure 1 The step flow chart of the urea system diagnosis method provided for the embodiment of the present application;

[0062] Figure 2 The step flow chart of the pressure abnormality detection method using the difference between the second pressure value and the ambient pressure value and the pressure change trend in the embodiment of the present application;

[0063] Figure 3 The step flow chart of the pressure abnormality detection method using multiple cycles in the embodiment of the present application;

[0064] Figure 4 The step flow chart of the method for excluding the influence of the pressure abnormality of the delivery pipe in the urea system on the detection result of the pressure sensor in the embodiment of the present application;

[0065] Figure 5 The step flow chart of the pressure abnormality detection of the urea system in the embodiment of the present application;

[0066] Figure 6 The control logic diagram of the urea system fault diagnosis method provided for the embodiment of the present application;

[0067] Figure 7 The structure schematic diagram of the urea system fault diagnosis device provided for the embodiment of the present application;

[0068] Figure 8 The structure schematic diagram of the urea system provided for the embodiment of the present application;

[0069] Figure 9 A structure diagram of a sealing cover provided by an embodiment of the present application is shown in FIG. 1.

[0070] Figure 10 A structure diagram of a sealing cover provided by an embodiment of the present application is shown in FIG. 1. Figure 9 A structure diagram of a sealing cover provided by an embodiment of the present application is shown in FIG. 1.

[0071] The reference numerals are explained as follows: 1, pressure sensor; 2, filling pipe; 3, sealing cover; 31, cover plate; 32, electrically controlled switch; 321, spring; 322, energizing coil; 33, air hole; 331, semi-permeable membrane; 4, urea tank; 41, breather valve; 5, urea pump; 6, conveying pipe; 7, injector. DETAILED DESCRIPTION

[0072] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0073] The current urea system adjusts the pressure of the urea system through a urea control unit to make the urea system run normally. Meanwhile, the urea control unit judges whether there is pressure abnormality in the urea system through pressure data collected by a pressure sensor in the urea system to timely report errors and remind users to maintain.

[0074] However, since the current urea system judges the pressure abnormality through the data of the pressure sensor, the pressure abnormality judgment through the data collected by the pressure sensor may lead to misjudgment of the fault without guaranteeing that the pressure sensor itself does not have a fault, so that the real cause of the fault cannot be found, and the maintenance process needs to be rechecked, which is time-consuming and laborious.

[0075] A urea system fault diagnosis method and device, a urea system and a vehicle will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0076] Referring to Figure 1 , Figure 1 A step flowchart of a urea system fault diagnosis method provided by an embodiment of the present application is shown, the urea system includes a pressure sensor for detecting the internal pressure of the urea system, and the method specifically includes:

[0077] In step S1, in response to the vehicle being powered on, a first pressure value collected by the pressure sensor and an environmental pressure value of the environment where the vehicle is located are acquired.

[0078] The fault diagnosis of the urea system is performed when the vehicle is just powered on, so that whether the urea system can normally work before the user starts the vehicle is determined, and then the user can conveniently maintain the fault in time. Therefore, when the vehicle is powered on, the data collected by the pressure sensor of the urea system is acquired to perform fault detection.

[0079] It can be understood that, since the urea system itself has a vent valve connected with the outside environment, when the urea system is working, the pressure in the urea system is adjusted to be stable. When the vehicle is just powered on, the urea system is in an idle state, at this time, the pressure in the urea system is stable in a range that is not much different from the ambient pressure, and then it can be determined whether the pressure of the urea system is abnormal according to the comparison between the pressure of the urea system and the ambient pressure. Thus, in addition to obtaining the pressure value collected by the pressure sensor, the pressure value of the environment in which the vehicle is located is also obtained. The ambient pressure of the environment in which the vehicle is located can be collected by the pressure sensor of the vehicle body.

[0080] In step S2, pressure abnormality detection is performed on the urea system based on the first pressure value and the ambient pressure value, and the pressure abnormality detection is used to determine whether the urea system has a pressure abnormality.

[0081] Since the ambient pressure can be used to determine whether the urea system has a pressure abnormality, the pressure abnormality detection of the urea system can be to compare the first pressure value obtained with the ambient pressure value to determine whether the first pressure value is the ambient pressure value to determine whether the urea system has a pressure abnormality.

[0082] In some embodiments, the urea system and the ambient pressure value can not be completely consistent, but there is a small pressure difference, so the difference range between the normal pressure value of the urea system and the ambient pressure value when the urea system is not started can be calibrated in advance. Thus, in the fault diagnosis process, the difference between the first pressure value and the ambient pressure value can be determined first, and then it is determined whether the difference is within the calibrated range to determine whether the urea system has a pressure abnormality directly through the difference.

[0083] In step S3, in the case where the pressure abnormality exists, the urea system is controlled to exchange gas with the outside environment to equalize the gas pressure between the urea system and the outside environment through the gas exchange, and a second pressure value collected by the pressure sensor is obtained during the gas exchange.

[0084] Wherein, in the case where it is confirmed that the urea system has a pressure abnormality, it cannot be confirmed whether the pressure abnormality is caused by the failure of elements such as the vent valve of the urea system or the failure of the pressure sensor, so further detection is needed to determine the failed element after it is confirmed that the urea system has a pressure abnormality.

[0085] In the embodiment of the present application, the gas exchange between the urea system and the external environment is actually to connect the urea system with the external environment, so that the gas exchange occurs between the urea system and the external environment, and the gas pressure of the urea system becomes the environmental pressure. The method of connecting the urea system with the external environment is not specifically limited in the present application. A gas hole with a switch can be provided in the urea system to control the connection between the urea system and the external environment by controlling the switch. Alternatively, the urea system itself has an element, such as an electrically controlled switch for the cap of the filling pipe in the urea system, to control the connection between the urea system and the external environment by controlling the opening of the switch.

[0086] Specifically, if the urea system is connected with the external environment at this time, the pressure value of the urea system will undoubtedly gradually change to the environmental pressure value. At this time, if the data collected by the pressure sensor changes to approach the environmental pressure value, it can be determined that the pressure sensor is normally operating. If the data collected by the pressure sensor does not change or still exceeds the normal pressure range, it means that the pressure sensor has a fault. Therefore, the environmental pressure value is used to determine whether the fault occurs in the pressure sensor or other positions.

[0087] Therefore, in the case where it is confirmed that the urea system has a pressure abnormality, the urea system is connected with the external environment. At this time, due to the gas exchange between the urea system and the external environment, the urea system and the external environment gradually achieve pressure balance. In this process, the gas pressure of the urea system gradually approaches the environmental pressure. At this time, the data of the pressure sensor is acquired again, and the element with a fault in the urea system is determined again according to the data of the pressure sensor.

[0088] In step S4, the pressure abnormality detection is performed on the urea system based on the second pressure value and the environmental pressure value.

[0089] Since the gas exchange between the urea system and the external environment, the internal pressure of the urea system finally approaches the environmental pressure value. Therefore, the current urea system can be directly determined to have a pressure abnormality by comparing the second pressure value with the environmental pressure value. The scheme of performing the pressure abnormality detection on the urea system by comparing the second pressure value with the environmental pressure value can be the same as or different from step S2.

[0090] Specifically, it can be determined by directly comparing the difference between the second pressure value and the ambient pressure value with the preset difference value range. Whether the urea system still has a pressure anomaly. Considering that the pressure anomaly detection of the urea system this time is to determine the specific cause of the fault, that is, the element that has failed, therefore, it can also be that multiple second pressure values are obtained to determine the pressure change trend, thereby, through the pressure change trend and the difference between the second pressure value and the ambient pressure value, it is determined whether the detected pressure still has an anomaly, thereby improving the accuracy of the pressure anomaly detection; it can also be that multiple detections are performed, when the first detection determines that the pressure is abnormal, the pressure anomaly detection is performed again, and when multiple detections all show that the pressure is abnormal, it is determined that the urea system has a pressure anomaly, which can also improve the accuracy of the pressure anomaly detection.

[0091] Step S5, based on the result of the pressure anomaly detection, determining the element of the urea system that has failed from the multiple elements included in the urea system.

[0092] Specifically, in the case where the result of the pressure anomaly detection is that the pressure is normal, the element that has failed is determined to be the vent valve;

[0093] In the case where the result of the pressure anomaly detection is that the pressure is abnormal, the element that has failed is determined to be the pressure sensor.

[0094] Wherein, the urea system includes a urea tank, and a vent valve arranged on the urea tank, the vent valve is used to adjust the internal pressure of the urea system; when the urea system pressure detection is normal, it indicates that the pressure sensor is in a normal state, and the urea system indeed has a pressure anomaly, and since the pressure regulation in the urea system is performed by the vent valve, the pressure anomaly indicates that the vent valve does not play a role in pressure regulation, therefore, it is determined that the pressure failure cause of the urea system is the vent valve failure; and if the detection is still abnormal at this time, it indicates that the pressure sensor itself has a failure, therefore, it is determined that the pressure sensor of the urea system has a failure.

[0095] In some embodiments, after determining the pressure anomaly cause of the urea system, an alarm information can be sent to the user for the convenience of user maintenance, wherein the alarm information can carry the information of the element that has failed, thereby the user can perform fault maintenance according to the alarm information, since the fault element is confirmed during the pressure anomaly detection, the fault element can be directly maintained, thereby avoiding the problem of time-consuming and laborious maintenance when the fault cause needs to be determined again.

[0096] The fault diagnosis method of the urea system provided by the embodiment of the present application determines whether the pressure is abnormal by acquiring the pressure data of the urea system collected by the pressure sensor when the vehicle is powered on, controls the urea system to communicate with the outside world when the pressure is abnormal, and gradually changes the pressure of the urea system to the ambient pressure. In this case, the pressure data collected by the pressure sensor is reacquired to determine whether the element that fails in the urea system is the pressure sensor or other elements. Thus, by connecting the urea system with the environment, the pressure of the urea system stops changing after the urea system is connected with the environment, and the pressure is constant as the ambient pressure. Therefore, whether the pressure sensor fails can be determined by the ambient pressure value, and the fault element of the urea system is determined, so that the maintenance process does not need to re-detect the element that fails in the urea system, and the maintenance efficiency is improved.

[0097] In the embodiment, the second pressure abnormality detection is to determine the element that fails from the plurality of elements of the urea system. Therefore, to ensure the accuracy of the detection result, not only the difference between the second pressure value and the ambient pressure value is used to determine whether the urea system has pressure abnormality, but also the pressure change trend is combined to determine whether the urea system has pressure abnormality. The pressure abnormality of the urea system can also be determined by multiple pressure abnormality detections, and the pressure abnormality of the urea system is determined when multiple detections are abnormal.

[0098] Specifically, in the case of jointly judging by the difference between the second pressure value and the ambient pressure value and the pressure change trend, a plurality of second pressure values are included, the plurality of second pressure values are acquired in chronological order during the gas exchange process, and the pressure change trend of the urea system is determined based on the plurality of second pressure values. Figure 2 , Figure 2 A step flow chart of the pressure abnormality detection by the way of jointly judging by the difference between the second pressure value and the ambient pressure value and the pressure change trend is shown in FIG. 2. As shown in FIG. 2, the pressure abnormality detection step specifically includes: Figure 2

[0099] Step S201, determining the pressure change trend of the urea system during the gas exchange process based on the plurality of second pressure values.

[0100] Since the second pressure value is acquired in chronological order, after obtaining the plurality of second pressure values, the second pressure values can be sorted based on the time sequence to determine the pressure change trend of the urea system, that is, whether the pressure of the urea system rises, falls or fluctuates within the time range of acquiring the second pressure value.

[0101] ​In an embodiment of the present invention, to determine the pressure change of the urea system during gas exchange, multiple pressure values ​​are acquired during the gas exchange process. Specifically, while controlling gas exchange between the urea system and the external environment, pressure data collected by the pressure sensor may be acquired, and the acquisition may continue until the pressure stops changing. Alternatively, a preset pressure acquisition duration may be set, and multiple second pressure values ​​may be acquired continuously for a preset duration after the gas exchange between the urea system and the external environment occurs. For example, after the urea system is connected to the external environment, it can reach equilibrium with the ambient pressure within 2 minutes. Therefore, a preset pressure acquisition duration of 2 minutes may be set. While controlling gas exchange between the urea system and the external environment occurs, pressure data collected by the pressure sensor may be acquired continuously until 2 minutes have elapsed.

[0102] Step S202 : determining a first pressure difference between each second pressure value and the ambient pressure value to obtain a plurality of first pressure differences.

[0103] Since the presence of a urea system pressure anomaly is determined by combining the pressure difference and the pressure variation trend, in addition to obtaining the pressure variation trend, it is also necessary to determine the difference between multiple second pressure values ​​and the ambient pressure value. In this embodiment of the present invention, since multiple second pressure values ​​are obtained, the difference between each second pressure value and the ambient pressure value is obtained.

[0104] Step S203: determining whether abnormal pressure still exists in the urea system based on the plurality of first pressure differences and the pressure change trend.

[0105] Among them, considering that the second pressure values ​​corresponding to the multiple first pressure differences are obtained at different times, some second pressure values ​​are obtained during the pressure change process and cannot represent the system pressure after the urea system exchanges gas with the external environment. Therefore, after obtaining the multiple first pressure differences, it is necessary to determine the first pressure difference that can be used for pressure anomaly judgment from the multiple first pressure differences. In the embodiment of the present invention, the first pressure difference that can be used for pressure anomaly judgment is the first pressure difference corresponding to the second pressure value with a small pressure change or no change before and after the pressure.

[0106] Therefore, based on the plurality of first pressure differences and the pressure change trend, the step of determining whether the urea system still has abnormal pressure specifically includes:

[0107] Based on the pressure variation trend, determining a target pressure difference from the plurality of first pressure differences; wherein the target pressure difference is a first pressure difference corresponding to a second pressure value at which the pressure variation trend is in a flat stage;

[0108] When the target pressure difference is within a preset difference range and the pressure change trend is a preset trend, determining that the urea system pressure is normal;

[0109] In a case that the target pressure difference is not within the preset difference range and / or the pressure change trend is not the preset trend, it is determined that the urea system pressure is abnormal.

[0110] The preset difference range is a normal pressure difference range between the urea system and the environment when the urea system is not started. Specifically, the preset difference range can be determined by calibrating the minimum difference between the pressure of the urea system and the environment pressure when the vent valve of the urea system is blocked.

[0111] Specifically, the second pressure value after the pressure change is gentle can be determined according to the pressure change trend. For example, a plurality of second pressure values are plotted as a pressure change curve, and the horizontal segment in the pressure change curve is the second pressure value after the pressure change is gentle. Alternatively, the difference between the second pressure value before and after each second pressure value and the second pressure value can be determined. If the difference is less than a preset difference or the difference is 0, it is indicated that the second pressure value is the second pressure value after the pressure change trend is gentle. At this time, the first pressure difference corresponding to the second pressure value is taken as the target pressure difference, and whether the urea system still has a pressure abnormality is determined by the target pressure difference and the pressure change trend.

[0112] It can be understood that since the vent valve of the urea system is located on the urea tank, which is arranged at the chassis of the vehicle, the working environment is harsh, and the vehicle is prone to blockage when wading or in other bad road conditions. After the blockage, the pressure in the tank will change due to the continuous consumption of urea, causing the pressure in the urea tank to rise and exceed the ambient pressure. Therefore, the preset trend in the embodiment of the present application is a pressure decreasing trend.

[0113] In some embodiments, the pressure abnormality detection can also be multiple cycle detection. When multiple detections are all abnormal, it is confirmed that the urea system pressure is abnormal. That is, when the pressure abnormality is detected for the first time, the pressure abnormality detection is re-detected until a set number of detections is reached. At this time, if the pressure is still abnormal, it is indicated that the urea system has a pressure abnormality.

[0114] Specifically, referring to Figure 3 , Figure 3 a step flowchart of the pressure abnormality detection in a multiple cycle manner is shown, as shown in Figure 3 the specific steps of the pressure abnormality detection method include:

[0115] Step S301, determining a second pressure difference between the second pressure value and the ambient pressure value.

[0116] Step S302, in the case that the second pressure difference is not in the preset difference value range, the second pressure value is re-acquired, and the second pressure difference between the second pressure value and the ambient pressure value is re-determined.

[0117] Step S303, in the case that the number of times of re-acquiring the second pressure value reaches a preset number of times, and the second pressure difference corresponding to the second pressure value acquired at the last time is still not in the preset difference value range, it is determined that the urea system pressure is abnormal.

[0118] The preset number of times can be two, three or more, which is determined according to actual conditions. For example, the preset number of times is three. In the case that the first detection is not normal, the second detection is performed. If the second detection is normal, it is indicated that the urea system pressure is normal. If the second detection is not normal, the third detection is performed. If the third detection is normal, it is indicated that the urea system pressure is normal. If the third detection is not normal, it is determined that the urea system pressure is abnormal. Thus, by repeatedly detecting in the case that the detection result is pressure abnormality, the accuracy of the urea system pressure abnormality detection is improved.

[0119] In some embodiments, the urea system includes an injector and a delivery pipe connected to the injector. The injector adjusts the communication or disconnection of the urea system and the exhaust pipeline of the vehicle. In the process of drawing back urea or injecting urea, if there is an abnormal power-off condition, the injector will immediately close and the urea pump will stop working, causing part of the urea to accumulate in the delivery pipe, resulting in abnormal pressure of the delivery pipe, and further causing abnormal pressure detected by the pressure sensor. Therefore, before determining the faulty element of the urea system, the influence of the abnormal pressure of the delivery pipe needs to be ruled out.

[0120] Referring to Figure 4 , Figure 4 A step flow chart of a method for ruling out the influence of the abnormal pressure of the delivery pipe in the urea system on the detection result of the pressure sensor is shown. As shown in Figure 4 , the specific method includes:

[0121] Step S401, the urea system is controlled to communicate with the exhaust pipeline, so that the residual urea in the delivery pipe is injected into the exhaust pipeline.

[0122] Specifically, no matter whether the urea is injected into the exhaust pipeline or is sucked back during the process of remaining in the injector and the delivery pipeline, due to the forward rotation or the reverse rotation of the urea pump, a corresponding positive pressure or a negative pressure is generated, if power failure occurs suddenly at this time, the urea pump stops working, the injector is closed, and part of the urea remains in the delivery pipeline, causing abnormal pressure of the entire urea system; therefore, in order to exclude the pressure abnormality in this case, the injector of the urea system is opened to control the urea system to communicate with the exhaust pipeline. At this time, the air pressure of the urea system and the exhaust pipeline can be balanced, so that the remaining urea is injected into the exhaust pipeline.

[0123] In the communication process, a third pressure value collected by the pressure sensor is acquired, in step S402.

[0124] In step S403, based on the third pressure value and the ambient pressure value, the pressure abnormality detection is performed on the urea system to determine whether the urea system still has pressure abnormality.

[0125] In step S404, in the case that the pressure abnormality detection is performed on the urea system and it is determined that the urea system still has pressure abnormality, the urea system is controlled to exchange gas with the external environment.

[0126] In the embodiment of the present application, the third pressure value is the internal pressure value of the urea system collected by the pressure sensor when the urea system communicates with the exhaust pipeline, at this time, the third pressure value and the ambient pressure value are used for abnormality detection to exclude the pressure abnormality caused by abnormal power failure of the urea system. It should be noted that, in order to avoid the case that the third pressure value is acquired when the pressure of the urea system and the exhaust pipeline is not balanced, resulting in detection error, the third pressure value collected by the pressure sensor can be acquired after a preset time interval after the injector is opened. After the third pressure value is acquired, whether the urea system has pressure abnormality is determined according to the difference between the third pressure value and the ambient pressure value.

[0127] If the detection result shows that the urea system still has pressure abnormality, it means that the pressure abnormality is not caused by abnormal power failure of the urea system, but may be caused by the failure of the elements of the urea system, at this time, step S3 is performed to further exclude the cause of the pressure abnormality of the urea system to determine the position of the failure of the urea system; if the detection result shows that the urea system has normal pressure, it means that the urea system does not have pressure failure, and then the fault diagnosis can be directly completed.

[0128] In some embodiments, in the case that whether the urea system has pressure abnormality is determined according to the difference between the pressure value collected by the pressure sensor and the ambient pressure value, the specific steps of the pressure abnormality detection include:

[0129] Step S501, determine a third pressure difference between the current detected pressure value of the pressure sensor and the ambient pressure value.

[0130] Step S502, when the third pressure difference is within the preset difference value range, determine that the urea system pressure is normal.

[0131] Step S503, when the third pressure difference is not within the preset difference value range, determine that the urea system pressure is abnormal.

[0132] Specifically, since the two end point values in the preset difference value range are the minimum difference values of the urea system pressure in the case of urea system failure, within this range, it indicates that the pressure of the urea system is normal, and not within this range indicates that the pressure of the urea system is abnormal. In the embodiment of the application, the preset difference value range is related to the accuracy and range of the pressure sensor, and also related to the design of the urea system, so it can be obtained by calibration. The preset difference value range of the embodiment of the application is-350mbar~350mbar; wherein, the preset difference value range can not include the values at the end points, or can include the values at the end points.

[0133] Wherein, since only the difference between the pressure value obtained by the sensor and the ambient pressure value is used to determine whether the urea system pressure is normal, the accuracy is limited, therefore, it is more suitable for preliminary detection at power-on, and for exclusion of urea system abnormal power-off, if more accurate detection is required, detection can be performed by pressure change trend and difference value together, or by multiple detection and repeated confirmation.

[0134] The fault diagnosis method of the urea system provided by the embodiment of the application, in the case of pressure abnormality of the urea system, first excludes the pressure abnormality of the delivery pipe, and then controls the urea system to communicate with the external environment, so that the urea system and the external environment pressure are balanced, thereby, by comparing the ambient pressure value with the pressure value collected by the pressure sensor, based on the comparison result of the two, it can be determined that the reason for the urea system pressure abnormality is specifically because of the failure of the element or the failure of the pressure sensor; at the same time, since when comparing the data of the pressure sensor with the ambient pressure, the pressure change trend and the pressure difference are used together to determine whether the urea system has pressure abnormality, or the multiple detection method is used to determine whether the urea system has pressure abnormality, the accuracy of detection is improved; since the failure of the urea system can be accurately determined as the vent valve or the pressure sensor, the maintenance process is facilitated, and maintenance can be directly performed according to the prompt information, avoiding the need to determine the failed element during maintenance, which is time-consuming and laborious.

[0135] Next, the above process will be described in detail in conjunction with a specific example:

[0136] Referring to Figure 6 ,Figure 6 A control logic diagram of the fault diagnosis method of the urea system provided by the embodiment of the present application is shown in Figure 1. Figure 6 As shown in the figure, the method specifically comprises:

[0137] First, when the vehicle is powered on, the urea control unit is activated, i.e. starts to perform fault diagnosis on the urea system, to avoid driving problems.

[0138] When starting the diagnosis, the pressure data currently collected by the pressure sensor is acquired, and the ambient pressure data collected by the vehicle body pressure sensor is acquired. If the difference ΔP between the two is within the preset range, i.e. -350 mbar < ΔP < 350 mbar, it means that the pressure sensor is normal, and the pressure monitoring of the urea system can continue; if the difference between the two is not within the preset range, i.e. ΔP ≥ 350 mbar or ΔP ≤ -350 mbar, it means that the pressure of the urea system is abnormal.

[0139] At this time, it is first investigated whether it is caused by abnormal pressure of the delivery pipe, i.e. the ejector of the urea system is opened to make the delivery pipe communicate with the exhaust pipe. At this time, the current pressure value of the pressure sensor is re-acquired and compared with the ambient pressure value to determine the difference, so as to determine whether the urea system still has pressure abnormality based on the difference. For example, the data of the pressure sensor is acquired within 1 min after the ejector of the urea system is opened, and the difference between the data and the ambient pressure value is determined. If the difference ΔP between the two is within the preset range, i.e. -350 mbar < ΔP < 350 mbar, it means that the pressure sensor is normal, and the pressure monitoring of the urea system can continue; if the difference between the two is not within the preset range, i.e. ΔP ≥ 350 mbar or ΔP ≤ -350 mbar, it means that the urea system still has pressure abnormality.

[0140] If the urea system still has pressure abnormality, the urea system is controlled to communicate with the external environment, and the pressure of the urea system is adjusted to be consistent with the environment. At this time, pressure abnormality detection is performed again, and it is determined whether the pressure difference ΔP between the pressure value of the pressure sensor and the ambient pressure is within the preset difference range. For example, the detection data of the pressure sensor is continuously acquired within 2 min after the urea system is controlled to communicate with the external environment, to determine whether the pressure of the urea system is in a downward trend in this process, and to determine whether the difference ΔP between the pressure value of the urea system after the pressure is stable and the ambient pressure value is between -350 mbar and 350 mbar. If so, it means that the pressure value detected by the pressure sensor is normal, and thus it means that the fault of the urea system is that the vent valve is blocked. At this time, a warning of vent valve blockage can be sent to the user to remind the user to perform maintenance.

[0141] If the pressure value detected by the pressure sensor and the ambient pressure value and the pressure difference ΔP are not between 350 mbar and -350 mbar, it indicates that the data collected by the pressure sensor is abnormal, and then it indicates that the pressure sensor has a fault, at this time, an alarm for sending the pressure sensor fault can be sent to remind the user to repair.

[0142] Referring to Figure 7 , Figure 7 The structure of the fault diagnosis device of the urea system provided by the embodiment of the present application is shown in the figure. Figure 7 As shown in the figure, the urea system includes a pressure sensor for detecting the internal pressure of the urea system, and the device specifically includes:

[0143] The acquisition module 601 is configured to acquire a first pressure value collected by the pressure sensor and an ambient pressure value of an environment in which the vehicle is located in response to the vehicle being powered on.

[0144] The first execution module 602 is configured to perform pressure anomaly detection on the urea system based on the first pressure value and the ambient pressure value, and the pressure anomaly detection is used to determine whether the urea system has a pressure anomaly.

[0145] The control module 603 is configured to control the urea system to exchange gas with the external environment to equalize the air pressure between the urea system and the external environment through the gas exchange, and acquire a second pressure value collected by the pressure sensor during the gas exchange in the case of the pressure anomaly.

[0146] The second execution module 604 is configured to perform the pressure anomaly detection on the urea system based on the second pressure value and the ambient pressure value.

[0147] The determination module 605 is configured to determine, based on the pressure anomaly detection result, an element of the urea system that has a fault from a plurality of elements included in the urea system.

[0148] In some embodiments, the urea system includes a urea tank and a breather valve arranged on the urea tank, and the breather valve is used to adjust the internal pressure of the urea system, and the determination module 605 includes:

[0149] The first determination sub-module is configured to determine that the element having a fault is the breather valve in the case of the pressure anomaly detection result being pressure normal.

[0150] In the case of the pressure anomaly detection result being pressure abnormal, it is determined that the element having a fault is the pressure sensor.

[0151] In some embodiments, the second execution module 604 comprises:

[0152] a second determining submodule, configured to determine a pressure variation trend of the urea system during the gas exchange process based on the plurality of second pressure values;

[0153] a first obtaining submodule, configured to determine a first pressure difference between each of the second pressure values and the ambient pressure value, to obtain a plurality of first pressure differences;

[0154] a third determining submodule, configured to determine whether the urea system still has the pressure abnormality based on the plurality of first pressure differences and the pressure variation trend.

[0155] In some embodiments, the second execution module 604 further comprises:

[0156] a fourth determining submodule, configured to determine a second pressure difference between the second pressure value and the ambient pressure value;

[0157] a fifth determining submodule, configured to re-obtain the second pressure value and re-determine the second pressure difference between the second pressure value and the ambient pressure value when the second pressure difference is not within a preset difference range;

[0158] a sixth determining submodule, configured to determine that the urea system has the pressure abnormality when a number of times of re-obtaining the second pressure value reaches a preset number of times and a second pressure difference corresponding to the second pressure value obtained last time is still not within the preset difference range, wherein the preset difference range is a normal pressure difference range between the urea system and an environment in which the urea system is located when the urea system is not started.

[0159] In some embodiments, the urea system comprises an injector and a delivery pipe connected to the injector, and the injector adjusts communication or disconnection between the urea system and an exhaust pipeline of the vehicle; and the device further comprises:

[0160] a control module, configured to control the urea system to communicate with the exhaust pipeline, so that residual urea in the delivery pipe is injected into the exhaust pipeline;

[0161] a second obtaining module, configured to perform the pressure abnormality detection on the urea system based on the third pressure value and the ambient pressure value, to determine whether the urea system still has the pressure abnormality.

[0162] In some embodiments, the execution module 602 comprises:

[0163] a seventh determining sub-module, configured to determine a third pressure difference between the current detected pressure value and the ambient pressure value of the pressure sensor;

[0164] an eighth determining sub-module, configured to determine that the urea system pressure is normal when the third pressure difference is within the preset difference range;

[0165] determine that the urea system pressure is abnormal when the third pressure difference is not within the preset difference range.

[0166] Referring to Figure 8 , Figure 8 A structure diagram of a urea system provided by an embodiment of the present application is shown, the urea system being in communication connection with a urea control unit, the urea control unit being used to execute the fault diagnosis method of the urea system according to any one of the above embodiments, and the urea system specifically comprising:

[0167] a pressure sensor 1 and a filling pipe 2 provided with a sealing cap 3;

[0168] The pressure sensor 1 is used to detect the internal pressure of the urea system.

[0169] The filling pipe 2 is in communication with the inside of the urea system, and the filling pipe 2 is used to inject urea into the urea system; wherein the sealing cap 3 is provided with a cover plate 31 with an electric control switch 32, the cover plate 31 is used to adjust the communication or disconnection of the urea system with the external environment, and the electric control switch 32 is controlled by the urea control unit.

[0170] Specifically, the urea system further comprises a urea tank 4, a urea pump 5, a conveying pipe 6 and an injector 7 connected with the conveying pipe 6, and the pressure sensor 1 is arranged in a passage in communication between the urea tank 4 and the conveying pipe 6; the conveying pipe 6 is used to convey urea from the urea tank 4 into the injector 7, or convey urea from the injector 7 back to the urea tank 4; the urea tank 4 is provided with a breather valve 41 for adjusting the internal pressure of the urea tank 4. Wherein, the urea control unit is connected with the electric control switch 32 and the injector 7 respectively, so as to control the opening and closing of the electric control switch 32 and the injector 7; the urea control unit is also in communication connection with the pressure sensor 1, so as to obtain the pressure data collected by the pressure sensor 1.

[0171] In executing the above fault diagnosis method of the urea system, the pressure sensor 1 detects the internal pressure of the urea system and sends it to the urea control unit, so that the urea control unit judges whether the current urea system pressure is normal.

[0172] If the pressure is abnormal, the urea control unit controls the injector 7 to open, so that the urea system is in communication with the exhaust pipeline, thereby removing the residual urea in the conveying pipe 6, and eliminating the influence caused by the abnormal power-off of the urea system. After eliminating the abnormal power-off of the urea system, the internal pressure of the urea system detected by the pressure sensor 1 is reacquired, and if the pressure value is still abnormal, the electrically controlled switch 32 is controlled to open, so that the urea system is in communication with the outside based on the sealing cover 3, and then the pressure value of the pressure sensor 1 is reacquired to determine the faulty element in the urea system.

[0173] Referring to Figure 9 and Figure 10 , Figure 9 is a perspective view of the sealing cover 3 of the urea system, according to Figure 9 , it can be seen that the sealing cover 3 is provided with a gas hole 33 in communication with the outside, and the area of the cover plate 31 in the sealing cover 3 is slightly larger than the area of the gas hole 33; specifically, in the case where the fault diagnosis of the urea system is not performed, both ends of the cover plate 31 are in contact with the inner wall of the sealing cover 3 to close the gas hole 33, and only during the fault diagnosis of the urea system, the cover plate 31 is lowered based on the control signal of the urea control unit, i.e. when the electrically controlled switch 32 receives the signal of the urea control unit, so that the urea system is in communication with the outside environment.

[0174] Referring to Figure 10 , Figure 10 is an enlarged view of A in Figure 9 , according to Figure 10 , it can be seen that the electrically controlled switch 32 specifically includes a spring 321 and a power coil 322, one end of the spring 321 is connected to the cover plate 31, and the other end is fixed to the inner wall of the sealing cover 3. It can be understood that the cover plate 31 is made of a magnetic material, so that when it is necessary to make the urea system in communication with the outside, the power coil 322 is energized according to the instruction of the urea control unit, so that the power coil 322 generates a magnetic attraction to the cover plate 31, thereby lowering the cover plate 31 and making the gas hole 33 in communication with the urea system, so that the urea system can be in communication with the outside environment; and when the fault diagnosis of the urea system is completed, the power coil 322 can be de-energized according to the instruction of the urea control unit, at this time, the attraction of the power coil to the cover plate disappears, and the cover plate 31 reseals the gas hole 33 due to the elastic force of the spring 321.

[0175] In some embodiments, to avoid the blockage of the gas hole 33 and the difficulty in performing the fault detection of the urea system, a semi-permeable membrane 331 with an area comparable to that of the gas hole 33 is arranged on the side of the gas hole 33 close to the outside environment, so as to prevent liquid and impurities from blocking the gas hole 33 and ensure smooth airflow.

[0176] Based on the same inventive concept, the embodiments of the present application also provide a vehicle, which comprises a fault diagnosis unit for executing the fault diagnosis method of the urea system according to any one of the above embodiments.

[0177] The above merely provides the preferred embodiments of the present application and is not used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

[0178] For the method embodiments, in order to simply describe, all are expressed as a series of action combinations, but the person skilled in the art should know that the present application is not limited by the action sequence described, because according to the present application, certain steps can be in other sequence or simultaneously. Secondly, the person skilled in the art should know that the embodiments described in the specification all belong to the preferred embodiments, and the actions and components involved are not necessarily the necessary of the present application.

[0179] The above has introduced in detail the fault diagnosis method, device, urea system and vehicle of the present application, the principle and implementation mode of the present application have been described in this paper by applying specific examples, the above embodiment description is only used to help understand the method and core idea of the present application; at the same time, for the person skilled in the art, according to the idea of the present application, the specific implementation mode and application scope will have changes, and the above is not understood as the limitation of the present application.

Claims

1. A method for diagnosing a fault in a urea system, characterized in that: The urea system includes a pressure sensor for detecting an internal pressure of the urea system, and the urea system also includes an injector and a delivery pipe connected to the injector, wherein the injector adjusts the connection or disconnection between the urea system and an exhaust pipe of a vehicle. The method includes: In response to the vehicle being powered on, obtaining a first pressure value collected by the pressure sensor and an ambient pressure value of an environment in which the vehicle is located; performing a pressure anomaly detection on the urea system based on the first pressure value and the ambient pressure value, wherein the pressure anomaly detection is used to determine whether there is a pressure anomaly in the urea system; In the event of the pressure anomaly, controlling the urea system to perform gas exchange with an external environment, so as to balance the air pressure between the urea system and the external environment through the gas exchange, and obtaining a second pressure value collected by the pressure sensor during the gas exchange process; performing the pressure abnormality detection on the urea system based on the second pressure value and the ambient pressure value; Based on the result of the abnormal pressure detection, determining a component of the urea system that has failed from a plurality of components included in the urea system; Before controlling the urea system to exchange gas with the external environment, the method further includes: controlling the urea system to communicate with the exhaust pipe so that the residual urea in the delivery pipe is injected into the exhaust pipe; During the communication process, obtaining a third pressure value collected by the pressure sensor; performing the pressure abnormality detection on the urea system based on the third pressure value and the ambient pressure value to determine whether the pressure abnormality in the urea system still exists; The controlling the urea system to exchange gas with the external environment comprises: When the pressure abnormality detection is performed on the urea system and it is determined that the pressure abnormality still exists in the urea system, the urea system is controlled to perform gas exchange with the external environment.

2. The fault diagnosis method of the urea system according to claim 1, characterized in that: The urea system includes a urea tank and a vent valve provided on the urea tank, the vent valve being used to regulate the internal pressure of the urea system. The determining, based on the result of the abnormal pressure detection, of a component of the urea system having a fault from among a plurality of components included in the urea system, includes: When the result of the pressure abnormality detection is that the pressure is normal, determining that the faulty component is the vent valve; When the result of the pressure abnormality detection is pressure abnormality, it is determined that the faulty component is the pressure sensor.

3. The fault diagnosis method of the urea system according to claim 1, characterized in that: The method further includes: comprising: obtaining a plurality of second pressure values ​​in chronological order during the gas exchange process; and performing the pressure abnormality detection on the urea system based on the second pressure values ​​and the ambient pressure value, including: determining a pressure change trend of the urea system during the gas exchange process based on a plurality of the second pressure values; determining a first pressure difference between each second pressure value and the ambient pressure value to obtain a plurality of first pressure differences; Based on the plurality of first pressure differences and the pressure variation trend, it is determined whether the urea system still has a pressure abnormality.

4. The fault diagnosis method of the urea system according to claim 3, characterized in that: The determining whether the urea system still has abnormal pressure based on the plurality of first pressure differences and the pressure change trend includes: Based on the pressure variation trend, determining a target pressure difference from the plurality of first pressure differences; wherein the target pressure difference is a first pressure difference corresponding to a second pressure value at which the pressure variation trend is in a flat stage; When the target pressure difference is within a preset difference range and the pressure change trend is a preset trend, determining that the urea system pressure is normal; When the target pressure difference is not within the preset difference range and / or the pressure change trend is not a preset trend, it is determined that the urea system pressure is abnormal; wherein the preset difference range is a normal pressure difference range between the urea system and the environment when the urea system is not started.

5. The fault diagnosis method of the urea system according to claim 1, characterized in that: The performing the pressure abnormality detection on the urea system based on the second pressure value and the ambient pressure value includes: determining a second pressure difference between the second pressure value and the ambient pressure value; If the second pressure difference is not within the preset difference range, reacquiring the second pressure value and re-determining the second pressure difference between the second pressure value and the ambient pressure value; When the number of times the second pressure value is re-obtained reaches a preset number and the second pressure difference corresponding to the most recently obtained second pressure value is still not within the preset difference range, it is determined that the urea system pressure is abnormal; wherein the preset difference range is a normal pressure difference range between the urea system and the environment when the urea system is not started.

6. The fault diagnosis method of a urea system according to any one of claims 1 to 5, characterized in that: The performing pressure abnormality detection on the urea system includes: determining a third pressure difference between a pressure value currently detected by the pressure sensor and the ambient pressure value; When the third pressure difference is within a preset difference range, determining that the pressure of the urea system is normal; When the third pressure difference is not within the preset difference range, it is determined that the urea system pressure is abnormal.

7. A fault diagnosis device for a urea system, characterized in that: The urea system includes a pressure sensor for detecting the internal pressure of the urea system, an injector and a delivery pipe connected to the injector, and the injector adjusts the connection or disconnection between the urea system and the exhaust pipe of the vehicle; the device includes: an acquisition module, configured to acquire, in response to power-on of the vehicle, a first pressure value collected by the pressure sensor and an ambient pressure value of an environment in which the vehicle is located; a first execution module, configured to perform a pressure anomaly detection on the urea system based on the first pressure value and the ambient pressure value, wherein the pressure anomaly detection is configured to determine whether there is a pressure anomaly in the urea system; a control module, configured to control the urea system to perform gas exchange with an external environment when the pressure abnormality exists, so as to balance the air pressure between the urea system and the external environment through the gas exchange, and to obtain a second pressure value collected by the pressure sensor during the gas exchange; a second execution module, configured to perform the pressure abnormality detection on the urea system based on the second pressure value and the ambient pressure value; a determination module, configured to determine a faulty component of the urea system from among a plurality of components included in the urea system based on the abnormal pressure detection result; The control module is further configured to control the urea system to communicate with the exhaust pipe before controlling the urea system to exchange gas with the external environment, so that the residual urea in the delivery pipe is sprayed into the exhaust pipe; During the communication process, obtaining a third pressure value collected by the pressure sensor; performing the pressure abnormality detection on the urea system based on the third pressure value and the ambient pressure value to determine whether the pressure abnormality in the urea system still exists; When the pressure abnormality detection is performed on the urea system and it is determined that the pressure abnormality still exists in the urea system, the urea system is controlled to perform gas exchange with the external environment.

8. A urea system, characterized in that: The urea system is communicatively connected to a urea control unit, and the urea control unit is used to execute the fault diagnosis method of the urea system according to any one of claims 1 to 6; The urea system comprises: a pressure sensor and a filling pipe with a sealing cover at the pipe opening; Wherein, the pressure sensor is used to detect the internal pressure of the urea system; The filling pipe is connected to the interior of the urea system and is used to inject urea into the urea system. The sealing cover is provided with a cover plate having an electric control switch, and the cover plate is used to adjust the connection or disconnection between the urea system and the external environment. The electric control switch is controlled by the urea control unit.

9. A vehicle, characterized in that: The vehicle includes a fault diagnosis unit, which is used to execute the fault diagnosis method of the urea system according to any one of claims 1 to 6.

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