Fault diagnosis method and device for urea system, urea system and vehicle

Abstract

The invention provides a fault diagnosis method and device for a urea system, the urea system and a vehicle, belongs to the technical field of vehicles, and aims to detect faulted elements in the urea system and improve the maintenance efficiency by communicating the urea system with the outside under the condition that the pressure of the urea system is abnormal. The urea system comprises a pressure sensor, and the method comprises the steps that in response to vehicle power-on, a first pressure value collected by the pressure sensor and an environment pressure value of the environment where the vehicle is located are obtained; performing pressure anomaly detection on the urea system based on the first pressure value and the ambient pressure value; under the condition that the pressure is abnormal, the urea system is controlled to conduct gas exchange with the external environment, and a second pressure value collected by the pressure sensor is obtained in the gas exchange process; performing pressure anomaly detection on the urea system based on the second pressure value and the ambient pressure value; on the basis of the result of the pressure abnormality detection, a malfunctioning element is identified from among a plurality of elements included in the urea system.

Description

Technical Field

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

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

[0003] However, the current method of directly collecting data through pressure sensors to determine whether the system is normal does not take into account the impact of pressure sensor failure, resulting in the inability to determine the true cause of a urea system failure, making maintenance time-consuming and labor-intensive, and even leading to false alarms, resulting in ineffective maintenance of the urea system failure. Summary of the invention

[0004] In view of this, the present invention aims to provide a urea system fault diagnosis method, device, urea system and vehicle to solve the problem that the current urea system fault diagnosis method cannot determine the true cause of the fault, resulting in time-consuming and labor-intensive maintenance.

[0005] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0006] A fault diagnosis method for a urea system, wherein the urea system comprises a pressure sensor, wherein the pressure sensor is used to detect the internal pressure of the urea system, and the method comprises:

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

[0008] Based on the first pressure value and the ambient pressure value, performing a pressure abnormality detection on the urea system, wherein the pressure abnormality detection is used to determine whether there is a pressure abnormality in the urea system;

[0009] In the case of the abnormal pressure, controlling the urea system to perform gas exchange with the external environment, so that the air pressure between the urea system and the external environment is balanced through the gas exchange, and obtaining a second pressure value collected by the pressure sensor during the gas exchange process;

[0010] performing the pressure abnormality detection on the urea system based on the second pressure value and the ambient pressure value;

[0011] Based on the result of the pressure abnormality detection, a component of the urea system in which a fault occurs is determined from among a plurality of components included in the urea system.

[0012] Further, the urea system includes a urea tank, and a vent valve disposed on the urea tank, the vent valve is used to adjust the internal pressure of the urea system, and the component of the urea system that fails is determined from a plurality of components included in the urea system based on the result of the pressure abnormality detection, including:

[0013] When the result of the abnormal pressure detection is that the pressure is normal, determining that the faulty component is the vent valve;

[0014] When the result of the pressure abnormality detection is pressure abnormality, it is determined that the failed component is the pressure sensor.

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

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

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

[0018] Based on the plurality of first pressure differences and the pressure variation trend, it is determined whether the urea system still has pressure abnormality.

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

[0020] 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 gentle stage;

[0021] 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;

[0022] 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 in which it is located when the urea system is not started.

[0023] Further, the performing the pressure abnormality detection on the urea system based on the second pressure value and the ambient pressure value includes:

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

[0025] If the second pressure difference is not within the preset difference range, reacquire the second pressure value, and re-determine the second pressure difference between the second pressure value and the ambient pressure value;

[0026] When the number of times the second pressure value is re-acquired reaches a preset number of times and the second pressure difference corresponding to the second pressure value acquired most recently 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 in which it is located when the urea system is not started.

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

[0028] Controlling the urea system to communicate with the exhaust pipe so that the residual urea in the delivery pipe is sprayed into the exhaust pipe;

[0029] During the communication process, obtaining 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 pressure abnormality of the urea system still exists;

[0031] The controlling the urea system to exchange gas with the external environment comprises:

[0032] When the pressure abnormality detection is performed on the urea system and it is determined that the urea system still has an abnormality, the urea system is controlled to perform gas exchange with the external environment.

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

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

[0035] When the third pressure difference is within the preset difference range, determining that the pressure of the urea system is normal;

[0036] When the third pressure difference is not within the preset difference range, it is determined that the urea system pressure is abnormal.

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

[0038] The present invention provides a fault diagnosis method for a urea system, wherein the urea system includes a pressure sensor, and the pressure sensor is used to detect the internal pressure of the urea system. The method includes: in response to a vehicle being powered on, obtaining a first pressure value collected by the pressure sensor and an environmental pressure value of an environment in which the vehicle is located; based on the first pressure value and the environmental pressure value, performing a pressure anomaly detection on the urea system, wherein the pressure anomaly detection is used to determine whether there is a pressure anomaly in the urea system; in the case of the pressure anomaly, controlling the urea system to perform gas exchange with an external environment, so that the air pressure between the urea system and the external environment is balanced through the gas exchange, and obtaining a second pressure value collected by the pressure sensor during the gas exchange; based on the second pressure value and the environmental pressure value, performing the pressure anomaly detection on the urea system; and based on the result of the pressure anomaly detection, determining a component of the urea system that has a fault from among a plurality of components included in the urea system;

[0039] Therefore, the present invention determines whether there is a pressure abnormality in the urea system according to the pressure sensor data in the urea system when the vehicle is powered on. When there is a pressure abnormality, the urea system is connected to the environment. After the urea system is connected to the environment, it will exchange gas with the environment, so that the pressure of the urea system will gradually be consistent with the environmental pressure. Therefore, after the urea system is connected to the environment, the pressure value collected by the pressure sensor can be used again to confirm the component with fault in the urea system according to the environmental pressure value and the pressure value collected by the pressure sensor, that is, to determine whether it is a problem with the data collected by the pressure sensor itself or a problem with the component of the urea system itself; and because the fault cause of the abnormal pressure of the urea system can be determined, the faulty component in the urea system can be accurately located, and then the faulty component can be repaired, avoiding the problem of re-determining the fault cause before repair, which is time-consuming and labor-intensive.

[0040] Another object of the present invention is to provide a fault diagnosis device for a urea system to solve the problem that the current fault diagnosis method of the urea system cannot determine the true cause of the fault, resulting in time-consuming and labor-intensive maintenance.

[0041] To achieve the above object, the technical solution of the present invention is achieved as follows:

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

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

[0044] 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 used to determine whether there is a pressure anomaly in the urea system;

[0045] a control module, configured to control the urea system to perform gas exchange with the external environment in the presence of the abnormal pressure, 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;

[0046] 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;

[0047] The determination module is used to determine a faulty component of the urea system from a plurality of components included in the urea system based on the abnormal pressure detection result.

[0048] The advantages of the urea system fault diagnosis device and the urea system fault diagnosis method described above over the prior art are the same, and are not described in detail here.

[0049] Another object of the present invention 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 labor-intensive maintenance.

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

[0051] A urea system, the urea system is communicatively connected with a urea control unit, and the urea control unit is used to execute the fault diagnosis method of the urea system;

[0052] The urea system comprises: a pressure sensor and a filling pipe with a sealing cover at the pipe opening;

[0053] Wherein, the pressure sensor is used to detect the internal pressure of the urea system;

[0054] The filling pipe is connected to the interior of the urea system, and is used to inject urea into the urea system; wherein the sealing cover is provided with a cover plate with an electric control switch, and the cover plate is used to adjust the connection or disconnection between the urea system and the external environment, and the electric control switch is controlled by the urea control unit.

[0055] The advantages of the urea system and the fault diagnosis method of the urea system described above over the prior art are the same, and will not be elaborated herein.

[0056] Another object of the present invention is to provide a vehicle 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 labor-intensive maintenance.

[0057] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0058] A vehicle comprises: a fault diagnosis unit, wherein the fault diagnosis unit is used to execute the above-mentioned fault diagnosis method of the urea system.

[0059] The advantages of the vehicle and the above-mentioned urea system fault diagnosis method over the prior art are the same, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0061] Figure 1 A flowchart of the steps of the diagnostic method of the urea system provided by the embodiment of the present invention;

[0062] Figure 2 A flowchart of the steps of performing pressure anomaly detection by jointly judging the difference between the second pressure value and the ambient pressure value and the pressure change trend in an embodiment of the present invention;

[0063] Figure 3 This is a flowchart of the steps of performing pressure anomaly detection in a multiple-cycle manner in an embodiment of the present invention;

[0064] Figure 4 A flowchart of the steps of a method for eliminating the influence of abnormal pressure in a delivery pipe in a urea system on a detection result of a pressure sensor in an embodiment of the present invention;

[0065] Figure 5 A flowchart of the steps of abnormal pressure detection of a urea system in an embodiment of the present invention;

[0066] Figure 6 A control logic diagram of a fault diagnosis method for a urea system provided by an embodiment of the present invention;

[0067] Figure 7 A schematic diagram of the structure of a fault diagnosis device for a urea system provided by an embodiment of the present invention;

[0068] Figure 8 A schematic diagram of the structure of a urea system provided in an embodiment of the present invention;

[0069] Fig. 9 A schematic diagram of the structure of a sealing cover provided by an embodiment of the present invention;

[0070] Fig.10 for Fig. 9 The schematic diagram of the structure after the enlargement of A in the middle;

[0071] Explanation of the reference numerals: 1. pressure sensor; 2. filling pipe; 3. sealing cover; 31. cover plate; 32. electric switch; 321. spring; 322. energized coil; 33. air hole; 331. semipermeable membrane; 4. urea tank; 41. ventilation valve; 5. urea pump; 6. delivery pipe; 7. injector. DETAILED DESCRIPTION

[0072] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0073] The current urea system uses a urea control unit to adjust the pressure of the urea system to ensure the normal operation of the urea system. At the same time, the urea control unit also uses the pressure data collected by the pressure sensor in the urea system to determine whether there is abnormal pressure in the urea system, and report an error when doing so, reminding the user to perform maintenance.

[0074] However, since the pressure abnormality of the current urea system is judged by the data of the pressure sensor, if there is no guarantee that the pressure sensor itself has no faults, judging the pressure abnormality through the data collected by the pressure sensor may lead to misjudgment of the fault and the real cause of the fault cannot be found, so the maintenance process needs to be re-checked, which is time-consuming and labor-intensive.

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

[0076] Reference Figure 1 , Figure 1 A flowchart of a method for diagnosing a fault of a urea system provided by an embodiment of the present invention is shown. The urea system includes a pressure sensor, and the pressure sensor is used to detect the internal pressure of the urea system. The method specifically includes:

[0077] Step S1, in response to the vehicle being powered on, obtaining a first pressure value collected by the pressure sensor and an environmental pressure value of an environment in which the vehicle is located.

[0078] Among them, the fault diagnosis of the urea system is performed when the vehicle is just powered on, so as to check whether the urea system can work normally before the user starts the vehicle, so as to facilitate the user to repair the fault in time. Therefore, when the vehicle is powered on, the data collected by the pressure sensor of the urea system is obtained to perform fault detection.

[0079] It is understandable that, since the urea system itself has a vent valve connected to the external environment, when the urea system is working, the pressure in the urea system is adjusted to stabilize the pressure in the urea system. When the vehicle is just powered on, the urea system is not working. At this time, the pressure in the urea system is stabilized within a range that is not much different from the external environment, and then the pressure of the urea system can be compared with the environmental pressure to confirm whether the pressure of the urea system is abnormal. Therefore, in addition to obtaining the pressure value collected by the pressure sensor, the embodiment of the present invention also obtains the pressure value of the environment in which the vehicle is located. Among them, the pressure of the environment in which the vehicle is located can be collected by the pressure sensor of the vehicle body.

[0080] Step S2: performing pressure abnormality detection on the urea system based on the first pressure value and the ambient pressure value, wherein the pressure abnormality detection is used to determine whether there is pressure abnormality in the urea system.

[0081] Among them, since it is possible to determine whether there is a pressure abnormality in the urea system through the ambient pressure, the pressure abnormality detection of the urea system can be performed by comparing the acquired first pressure value with the ambient pressure value to determine whether the first pressure value is the ambient pressure value to judge whether there is a pressure abnormality in the urea system.

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

[0083] Step S3, in the case of the abnormal pressure, controlling the urea system to exchange gas with the 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.

[0084] Among them, when it is confirmed that there is a pressure abnormality in the urea system, it cannot be confirmed whether the pressure abnormality is caused by a failure of a component of the urea system such as a vent valve, or a failure of a pressure sensor. Therefore, after confirming the pressure abnormality in the urea system, further testing is required to determine the faulty component.

[0085] In the embodiment of the present invention, controlling the urea system to exchange gas with the external environment is actually to connect the urea system with the outside world, so that the urea system and the external environment exchange gas, and the air pressure of the urea system becomes the ambient air pressure. The present invention does not specifically limit the method of connecting the urea system with the outside world. An air hole with a switch can be provided in the urea system to control the connection between the urea system and the outside world by controlling the switch. It can also be through the elements of the urea system itself, such as setting the cover of the filling pipe in the urea system as an electric control switch, and controlling the opening of the cover to control the connection between the urea system and the outside world.

[0086] Specifically, considering that if the urea system is connected to the external environment at this time, the pressure value of the urea system will undoubtedly gradually change to the ambient pressure value. At this time, if the data collected by the pressure sensor changes to a value close to the ambient pressure value, it can be determined that the pressure sensor is operating normally. If the data collected by the pressure sensor remains unchanged or still exceeds the normal pressure range, it means that the pressure sensor is faulty. Therefore, the ambient pressure value is used to determine whether the fault occurs in the pressure sensor or elsewhere.

[0087] Therefore, when it is confirmed that there is abnormal pressure in the urea system, the urea system is controlled to be connected with the external environment. At this time, due to the gas exchange between the urea system and the external environment, the air pressure of the urea system and the external environment gradually achieves air pressure equilibrium. In this process, the air pressure of the urea system gradually approaches the ambient air pressure. At this time, the data of the pressure sensor is obtained again, and the test is performed again based on the data of the pressure sensor to determine the faulty component in the urea system.

[0088] Step S4: performing the pressure abnormality detection on the urea system based on the second pressure value and the ambient pressure value.

[0089] Since the urea system is controlled to exchange gas with the external environment, the internal pressure of the urea system will eventually approach the ambient pressure value. Therefore, it is possible to directly compare the second pressure value with the ambient pressure value to determine whether there is a pressure abnormality in the current urea system. The scheme for detecting pressure abnormality in the urea system by using the second pressure value and the ambient pressure value may be the same as step S2 or different.

[0090] Specifically, it is possible to directly use the comparison result between the difference between the second pressure value and the ambient pressure value and the preset difference range to determine whether the urea system still has pressure anomaly. Considering that the urea system performs pressure anomaly detection in order to determine the specific cause of the fault, that is, the faulty component, it is also possible to obtain multiple second pressure values ​​to determine the pressure change trend, thereby jointly confirming whether the detected pressure is still abnormal through the pressure change trend and the difference between the second pressure value and the ambient pressure value, thereby improving the accuracy of pressure anomaly detection; it is also possible to perform multiple tests, and when the pressure anomaly is determined in the first test, perform pressure anomaly detection again, and only when multiple tests show pressure anomaly, it is determined that the urea system has pressure anomaly, which can also improve the accuracy of pressure anomaly detection.

[0091] Step S5, based on the result of the abnormal pressure detection, determining a component of the urea system that has a fault from a plurality of components included in the urea system.

[0092] Specifically, when the result of the abnormal pressure detection is that the pressure is normal, determining that the faulty component is the vent valve;

[0093] When the result of the pressure abnormality detection is pressure abnormality, it is determined that the failed component is the pressure sensor.

[0094] The urea system includes a urea tank and a vent valve arranged on the urea tank, and the vent valve is used to adjust the internal pressure of the urea system; when the pressure detection of the urea system is normal, it means that the pressure sensor is in a normal state, and the urea system does have abnormal pressure. Since the pressure regulation in the urea system is performed through the vent valve, the abnormal pressure indicates that the vent valve does not play a role in pressure regulation. Therefore, it is confirmed that the cause of the pressure failure of the urea system is a failure of the vent valve; and if the abnormality is still detected at this time, it means that the pressure sensor itself is faulty. Therefore, it is determined that the pressure sensor of the urea system is faulty.

[0095] In some embodiments, after determining the cause of the abnormal pressure of the urea system, an alarm message may be sent to the user to facilitate maintenance by the user, wherein the alarm message may carry information about the faulty component. Thus, the user may perform fault repair according to the alarm message. Since the faulty component is confirmed during the pressure abnormality detection, the faulty component may be directly repaired, thus avoiding the need to re-determine the cause of the fault during maintenance, which is time-consuming and labor-intensive.

[0096] The fault diagnosis method of the urea system provided by the embodiment of the present invention 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. When the pressure is abnormal, the urea system is further controlled to be connected with the outside world so that the pressure of the urea system gradually changes to the ambient pressure. In this case, the pressure data collected by the pressure sensor is re-acquired to determine whether the component that fails in the urea system is the pressure sensor or other components. Therefore, by connecting the urea system with the environment, since after the urea system is connected with the environment, when the pressure of the urea system stops changing, its pressure is always the ambient pressure, therefore, it is possible to determine whether the pressure sensor is faulty by the ambient pressure value, and then determine the faulty component of the urea system, so that the maintenance process does not need to re-detect the faulty component in the urea system, thereby improving the maintenance efficiency.

[0097] In this embodiment, the second pressure abnormality detection is to determine the faulty component from multiple components 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 a pressure abnormality, but also the judgment of the pressure change trend can be combined to jointly determine whether the urea system has a pressure abnormality; or multiple pressure abnormality detections can be performed to determine the pressure abnormality of the urea system 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 the second pressure values ​​are included, and the plurality of the second pressure values ​​are obtained in chronological order during the gas exchange process, referring to Figure 2 , Figure 2 The flowchart of the steps of detecting pressure anomaly by using the difference between the second pressure value and the ambient pressure value and the pressure change trend to jointly judge is shown in FIG. Figure 2 As shown, the pressure anomaly detection step specifically includes:

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

[0100] Among them, since the second pressure values ​​are obtained in chronological order, after obtaining multiple second pressure values, the second pressure values ​​can be sorted based on the chronological order to determine the pressure change trend of the urea system, that is, within the time range of obtaining the second pressure values, whether the pressure of the urea system rises, falls or fluctuates.

[0101] In the embodiment of the present invention, in order to determine the pressure change of the urea system during the gas exchange process, multiple pressure values ​​are obtained during the gas exchange process. Specifically, while controlling the urea system to exchange gas with the external environment, the pressure data collected by the pressure sensor is obtained until the pressure stops changing, or the duration of pressure acquisition is preset, and multiple second pressure values ​​are continuously obtained within the preset duration after the urea system and the external environment are controlled to exchange gas. For example, after the urea system is connected to the external environment, it can be balanced with the ambient air pressure within 2 minutes, so the pressure acquisition duration can be preset to 2 minutes; when controlling the urea system to exchange gas with the external environment, the pressure data collected by the pressure sensor is continuously obtained until 2 minutes are reached.

[0102] Step S202: 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.

[0103] Among them, since the pressure difference and the pressure change trend are used to jointly determine whether the urea system has pressure abnormality, in addition to obtaining the pressure change trend, it is also necessary to determine the difference between multiple second pressure values ​​and the ambient pressure value. In the embodiment of the present invention, since multiple second pressure values ​​are obtained, at this time, 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 variation 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 abnormality judgment from the multiple first pressure differences. In the embodiment of the present invention, the first pressure difference that can be used for pressure abnormality judgment is the first pressure difference corresponding to the second pressure value with a small or no pressure change before and after.

[0106] Therefore, based on the plurality of first pressure differences and the pressure change trends, 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 gentle 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] 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.

[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 defined by calibrating the minimum difference between the pressure of the urea system and the ambient pressure when the vent valve of the urea system is blocked.

[0111] Specifically, the second pressure value after the pressure change is smoothed can be determined according to the pressure change trend, such as plotting multiple second pressure values ​​as a pressure change curve, and the horizontal section in the pressure change curve is the second pressure value after the pressure is smoothed; or the difference between the second pressure value before and after each second pressure value and the second pressure value can be determined, and if the difference is less than the preset difference or the difference is 0, it means that the second pressure value is the second pressure value in the smooth stage of the pressure change trend. At this time, the first pressure difference corresponding to the second pressure value is used as the target pressure difference, and the target pressure difference and the pressure change trend are used to jointly determine whether the urea system still has pressure abnormality.

[0112] It can be understood that since the vent valve of the urea system is located on the urea tank, the urea tank is arranged on the chassis of the vehicle and has a harsh working environment, it is easy to get blocked when the vehicle is wading or in other bad road conditions. After the blockage, the air 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 invention is a pressure decrease trend.

[0113] In some embodiments, the pressure abnormality detection can also be a multiple-cycle detection. Only when multiple detections are abnormal, the urea system pressure abnormality is confirmed; that is, when the pressure abnormality is detected for the first time, the pressure abnormality detection is re-tested until the set number of detections is reached. If the pressure is still abnormal at this time, it means that the urea system has a pressure abnormality.

[0114] Specifically, refer to Figure 3 , Figure 3 A flowchart of the steps of performing pressure anomaly detection in a multiple-cycle manner is shown. Figure 3 As shown, the specific steps of the pressure anomaly detection method include:

[0115] Step S301: determine a second pressure difference between the second pressure value and the ambient pressure value.

[0116] Step S302: if the second pressure difference is not within a preset difference range, reacquire the second pressure value, and re-determine the second pressure difference between the second pressure value and the ambient pressure value.

[0117] Step S303: when the number of times the second pressure value is re-obtained reaches a preset number and the second pressure difference corresponding to the second pressure value most recently obtained is still not within the preset difference range, it is determined that the urea system pressure is abnormal.

[0118] The preset number of times may be two, three or more times, depending on the actual situation. For example, if the preset number of times is three times, then if the first detection is abnormal, a second detection is performed. If the second detection is normal, it means that the pressure of the urea system is normal; if the second detection is abnormal, a third detection is performed. If the third detection is normal, it means that the pressure of the urea system is normal; if the third detection is abnormal, it is determined that the pressure of the urea system is abnormal. Therefore, by repeating the detection multiple times when the detection result is abnormal pressure, the accuracy of the abnormal pressure detection of the urea system is improved.

[0119] In some embodiments, the urea system includes 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. When the urea system is withdrawing urea or injecting urea, if there is an abnormal power failure, the injector will be immediately closed and the urea pump will stop working, causing part of the urea to accumulate in the delivery pipe, resulting in abnormal pressure in the delivery pipe, and further causing abnormal pressure detected by the pressure sensor. Therefore, before determining the faulty component of the urea system, it is necessary to eliminate the influence of the abnormal pressure in the delivery pipe.

[0120] Reference Figure 4 , Figure 4 The flowchart of the method for eliminating the influence of abnormal pressure in the delivery pipe of the urea system on the detection result of the pressure sensor is shown as follows: Figure 4 As shown, the specific methods include:

[0121] Step S401, 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.

[0122] Specifically, whether urea is injected into the exhaust pipe or is withdrawn and retained in the injector and delivery pipe, the positive or negative pressure is generated by the forward or reverse rotation of the urea pump. If a power failure occurs suddenly at this time, the urea pump stops working, the injector is closed, and some urea residue is retained in the delivery pipe, causing abnormal pressure in the entire urea system; therefore, in order to eliminate the abnormal pressure in this case, the injector of the urea system is opened to control the connection between the urea system and the exhaust pipe. At this time, the air pressure of the urea system and the exhaust pipe can be balanced, so that the retained urea is injected into the exhaust pipe.

[0123] Step S402: during the connection process, obtaining a third pressure value collected by the pressure sensor.

[0124] Step S403: performing 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 pressure abnormality.

[0125] Step S404: 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, controlling the urea system to perform gas exchange with the external environment.

[0126] In the embodiment of the present invention, the third pressure value is the internal pressure value of the urea system collected by the pressure sensor when the urea system is connected to the exhaust pipe. At this time, the abnormality detection is performed through the third pressure value and the ambient pressure value to exclude the pressure abnormality caused by the abnormal power failure of the urea system. It should be noted that in order to avoid the third pressure value being obtained when the pressure of the urea system and the exhaust pipe is not balanced, resulting in detection errors, the third pressure value collected by the pressure sensor can be obtained again after a preset time interval after the injector is turned on. After the third pressure value is obtained, it is determined whether there is a pressure abnormality in the urea system based on the difference between the third pressure value and the ambient pressure value.

[0127] If the test result shows that the urea system still has abnormal pressure, it means that the abnormal pressure is not caused by abnormal power failure of the urea system, but may be caused by a component failure of the urea system. At this time, the above step S3 is performed to further eliminate the cause of the abnormal pressure of the urea system to determine the location of the urea system failure; if the test result shows that the pressure of the urea system is normal, it means that there is no pressure failure in the urea system, and the fault diagnosis can be completed directly.

[0128] In some embodiments, when determining whether there is a pressure abnormality in the urea system by 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: determining a third pressure difference between a pressure value currently detected by the pressure sensor and the ambient pressure value.

[0130] Step S502: When the third pressure difference is within the preset difference range, determining that the urea system pressure is normal.

[0131] Step S503: When the third pressure difference is not within the preset difference range, determining that the urea system pressure is abnormal.

[0132] Specifically, since the two endpoint values ​​in the preset difference range are the minimum difference of the urea system pressure in the case of a urea system failure, if they are within this range, it means that the pressure of the urea system is normal, and if they are not within this range, it means that the pressure of the urea system is abnormal. In the embodiment of the present invention, the preset difference range is related to the accuracy and range of the pressure sensor and the design of the urea system, and therefore, can be obtained by calibration. The preset difference range of the embodiment of the present invention is -350mbar to 350mbar; wherein, the preset difference range may not include the values ​​at the endpoints, or may include the values ​​at the endpoints.

[0133] Among them, 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 when power is turned on and to exclude abnormal power failure of the urea system. If more accurate detection is required, the pressure change trend and the difference can be used for detection together, or repeated confirmation can be performed through multiple tests.

[0134] The fault diagnosis method of the urea system provided by the embodiment of the present invention eliminates the abnormal pressure of the delivery pipe first when the urea system has abnormal pressure, and then controls the communication between the urea system and the external environment to balance the air pressure of the urea system and the external environment. Therefore, by comparing the ambient pressure value with the pressure value collected by the pressure sensor, it can be determined based on the comparison result whether the cause of the abnormal pressure of the urea system is due to the failure of a component therein or the failure of the pressure sensor. At the same time, when comparing the data of the pressure sensor with the ambient pressure, the pressure change trend and the pressure difference are used to jointly determine the pressure difference or to use multiple detections to determine whether the urea system has abnormal pressure, thereby improving the accuracy of the detection. Since it can be accurately determined whether the fault of the urea system is the vent valve or the pressure sensor, the maintenance process is facilitated, and maintenance can be performed directly according to the prompt information, avoiding the need to determine the faulty component during the maintenance process, which is time-consuming and labor-intensive.

[0135] The following is a detailed explanation of the above process with a specific example:

[0136] Reference Figure 6 , Figure 6 FIG. 4 shows a control logic diagram of a fault diagnosis method for a urea system provided by an embodiment of the present invention. Figure 6 As shown, the method specifically includes:

[0137] First, when the vehicle is powered on, the urea control unit is activated and begins to diagnose faults in the urea system to avoid driving problems.

[0138] When the diagnosis starts, the pressure data currently collected by the pressure sensor and the ambient pressure data collected by the vehicle body pressure sensor are obtained. If the difference △P between the two is within the preset range, that is, -350mbar<△P<350mbar, it means that the pressure sensor is normal and the pressure monitoring of the urea system can be continued; if the difference between the two is not within the preset range, that is, △P≥350mbar or △P≤-350mbar, it means that the pressure of the urea system is abnormal;

[0139] At this time, first check whether it is caused by abnormal pressure in the delivery pipe, that is, control the injector of the urea system to open, so that the delivery pipe is connected to the exhaust pipe. At this time, re-acquire the current pressure value of the pressure sensor, compare it with the ambient pressure value, determine the difference, and determine whether the urea system still has abnormal pressure based on the difference; if the data of the pressure sensor is obtained within 1 minute of opening the urea system injector, and the difference between it and the ambient pressure value is determined, if the difference △P between the two is within the preset range, that is, -350mbar<△P<350mbar, it means that the pressure sensor is normal and the pressure monitoring of the urea system can be continued; if the difference between the two is not within the preset range, that is, △P≥350mbar or △P≤-350mbar, it means that the urea system still has abnormal pressure;

[0140] If the urea system still has abnormal pressure, the urea system is controlled to be connected to the external environment, and the pressure of the urea system is adjusted to be consistent with the environment. At this time, the pressure abnormality detection is performed again to check whether the pressure value of the pressure sensor continues to decrease and whether the pressure difference △P between the pressure of the pressure sensor and the ambient pressure detected last is within the preset difference range; for example, the detection data of the pressure sensor is continuously obtained within 2 minutes after the urea system is controlled to be connected to the external environment to determine whether the pressure of the urea system is on a downward trend during this process, and whether the difference △P between the pressure value after the urea system pressure is stabilized and the ambient pressure value is between -350mbar and 350mbar; if so, it means that the pressure value detected by the pressure sensor is normal, which further indicates 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, the ambient pressure value and the pressure difference △P are not between 350mbar and -350mbar, it means that the data collected by the pressure sensor is abnormal, which further indicates that the pressure sensor is faulty. At this time, a warning of the pressure sensor failure can be sent to the user to remind the user to repair it.

[0142] Reference Figure 7 , Figure 7 FIG. 4 shows a schematic diagram of the structure of a fault diagnosis device for a urea system provided by an embodiment of the present invention. Figure 7 As shown, the urea system includes a pressure sensor, and the pressure sensor is used to detect the internal pressure of the urea system. The device specifically includes:

[0143] An acquisition module 601 is used for acquiring, in response to the vehicle being powered on, a first pressure value collected by the pressure sensor and an environmental pressure value of an environment in which the vehicle is located;

[0144] A first execution module 602 is used to perform pressure abnormality detection on the urea system based on the first pressure value and the ambient pressure value, wherein the pressure abnormality detection is used to determine whether there is pressure abnormality in the urea system;

[0145] A control module 603 is used for controlling the urea system to perform gas exchange with the 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 obtaining a second pressure value collected by the pressure sensor during the gas exchange process;

[0146] A second execution module 604 is used to perform the pressure abnormality detection on the urea system based on the second pressure value and the ambient pressure value;

[0147] The determination module 605 is used to determine the faulty component of the urea system from among the multiple components included in the urea system based on the abnormal pressure detection result.

[0148] In some embodiments, the urea system includes a urea tank, and a vent valve disposed on the urea tank, the vent valve is used to adjust the internal pressure of the urea system, and based on the result of the pressure abnormality detection, the determination module 605 includes:

[0149] A first determination submodule, configured to determine that the faulty component is the vent valve when the result of the pressure abnormality detection is that the pressure is normal;

[0150] When the result of the pressure abnormality detection is pressure abnormality, it is determined that the failed component is the pressure sensor.

[0151] In some embodiments, the second pressure values ​​are multiple, and the second pressure values ​​are acquired in chronological order during the gas exchange process; the second execution module 604 includes:

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

[0153] A first acquisition 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] The third determination submodule is configured to determine whether the urea system still has abnormal pressure based on the plurality of first pressure differences and the pressure variation trend.

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

[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 determination submodule, configured to reacquire the second pressure value and re-determine a 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 determination submodule, configured to determine that the urea system pressure is abnormal when the number of times the second pressure value is re-acquired reaches a preset number of times and the second pressure difference corresponding to the second pressure value acquired most recently is still not within the preset difference range; wherein the preset difference range is a normal pressure difference range between the urea system and the environment in which it is located when the urea system is not started.

[0159] In some embodiments, the urea system includes 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 also includes:

[0160] a control module, used for controlling the urea system to communicate with the exhaust pipe so that the residual urea in the delivery pipe is sprayed into the exhaust pipe;

[0161] The second acquisition module is 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 includes:

[0163] a seventh determination submodule, configured to determine a third pressure difference between a pressure value currently detected by the pressure sensor and the ambient pressure value;

[0164] an eighth determination submodule, configured to determine that the pressure of the urea system is normal when the third pressure difference is within the preset difference range;

[0165] When the third pressure difference is not within the preset difference range, it is determined that the urea system pressure is abnormal.

[0166] Reference Figure 8 , Figure 8 The structural schematic diagram of a urea system provided by an embodiment of the present invention is shown. The urea system is in communication connection with a urea control unit. The urea control unit is used to execute the fault diagnosis method of the urea system described in any of the above embodiments. The urea system specifically includes:

[0167] A pressure sensor 1 and a filling pipe 2 with a sealing cover 3 at the pipe opening;

[0168] Wherein, the pressure sensor 1 is used to detect the internal pressure of the urea system;

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

[0170] Specifically, the urea system further includes a urea tank 4, a urea pump 5, a delivery pipe 6, and an injector 7 connected to the delivery pipe 6. The pressure sensor 1 is arranged in a channel connecting the urea tank 4 and the delivery pipe 6; the delivery pipe 6 is used to deliver urea from the urea tank 4 to the injector 7, or to deliver urea from the injector 7 back to the urea tank 4; the urea tank 4 is provided with a vent valve 41 for adjusting the internal pressure of the urea tank 4. The urea control unit is respectively connected to the electric control switch 32 and the injector 7 to control the opening and closing of the electric control switch 32 and the injector 7; the urea control unit is also connected to the pressure sensor 1 in communication to obtain the pressure data collected by the pressure sensor 1.

[0171] When executing the above-mentioned 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 determines whether the current pressure of the urea system is normal.

[0172] If the pressure is abnormal, at this time, the urea control unit controls the injector 7 to open, so that the urea system is connected to the exhaust pipe, thereby removing the residual urea in the delivery pipe 6 and eliminating the influence caused by the abnormal power failure of the urea system. After eliminating the abnormal power failure of the urea system, the internal pressure of the urea system detected by the pressure sensor 1 is re-obtained. If the pressure value is still abnormal, the electronic control switch 32 is controlled to open, so that the urea system is connected to the outside world based on the sealing cover 3, and then the pressure value is stabilized near the ambient pressure. After that, the pressure value of the pressure sensor 1 is re-obtained to determine the faulty component in the urea system.

[0173] Among them, refer to Fig. 9 and Fig.10 , Fig. 9 A perspective view of the sealing cover 3 of the urea system, according to Fig. 9 It can be seen that the sealing cover 3 is provided with an air hole 33 connected to the outside, and the area of ​​the cover plate 31 in the sealing cover 3 is slightly larger than the area of ​​the air hole 33; specifically, when 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 air hole 33, and only during the fault diagnosis of the urea system, the cover plate 31 is opened based on the control signal of the urea control unit, that is, when the electric control switch 32 receives the signal of the urea control unit, the cover plate 31 is moved down to connect the urea system with the external environment.

[0174] Among them, refer to Fig.10 , Fig.10 for Fig. 9 The enlarged view of point A in the middle, according to Fig.10 It can be seen that the electric control switch 32 specifically includes a spring 321 and a power-on 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 magnetic material, so that when the urea system needs to be connected to the outside, the power-on coil 322 is energized according to the instruction of the urea control unit, so that the power-on coil 322 generates magnetic attraction to the cover plate 31, thereby the cover plate 31 moves down, the air hole 33 is connected to the urea system, and the urea system can be connected to the external environment; and when the fault diagnosis of the urea system is completed, the power-on coil 322 can be stopped according to the instruction of the urea control unit, at this time, the attraction of the power-on coil to the cover plate disappears, and the cover plate 31 re-seals the air hole 33 due to the elastic force of the spring 321.

[0175] In some embodiments, in order to avoid clogging of the pore 33 and difficulty in fault detection of the urea system, a semipermeable membrane 331 with an area equivalent to the pore 33 is provided on the side of the pore 33 close to the external environment. The semipermeable membrane 331 prevents liquid and impurities from clogging the pore 33, thereby ensuring smooth airflow.

[0176] Based on the same inventive concept, an embodiment of the present invention further provides a vehicle, the vehicle comprising a fault diagnosis unit, the fault diagnosis unit being used to execute the fault diagnosis method of the urea system described in any one of the above embodiments.

[0177] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0178] For the method embodiments, for the sake of simplicity, they are all described as a series of action combinations, but those skilled in the art should know that the present invention is not limited by the order of the actions described, because according to the present invention, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and components involved are not necessarily required by the present invention.

[0179] The above is a detailed introduction to a urea system fault diagnosis method, device, urea system and vehicle provided by the present invention. Specific examples are used herein to illustrate the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for fault diagnosis of a urea system, characterized in that: The urea system comprises a pressure sensor, and the pressure sensor is used to detect the internal pressure of the urea system. The method comprises: In response to the vehicle being powered on, acquiring a first pressure value collected by the pressure sensor and an ambient pressure value of an environment in which the vehicle is located; Based on the first pressure value and the ambient pressure value, performing a pressure abnormality detection on the urea system, wherein the pressure abnormality detection is used to determine whether there is a pressure abnormality in the urea system; In the case of the abnormal pressure, controlling the urea system to perform gas exchange with the external environment, so that the air pressure between the urea system and the external environment is balanced 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 pressure abnormality detection, a component of the urea system in which a fault occurs is determined from among a plurality of components included in the urea system.

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 disposed on the urea tank, the vent valve being used to adjust the internal pressure of the urea system, and the component of the urea system that fails is determined from a plurality of components included in the urea system based on the result of the abnormal pressure detection, including: When the result of the abnormal pressure 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 failed component is the pressure sensor.

3. The fault diagnosis method of the urea system according to claim 1, characterized in that: The method comprises: comprising: obtaining a plurality of second pressure values ​​in a chronological order during the gas exchange process; and performing the pressure abnormality detection on the urea system based on the second pressure value and the ambient pressure value, comprising: 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 of the second pressure values ​​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 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 gentle 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 in which it is located 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, reacquire the second pressure value, and re-determine 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-acquired reaches a preset number of times and the second pressure difference corresponding to the second pressure value acquired most recently 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 in which it is located when the urea system is not started.

6. The fault diagnosis method of the urea system according to claim 1, characterized in that: The urea system comprises an injector and a delivery pipe connected to the injector, wherein the injector regulates the connection or disconnection between the urea system and the exhaust pipe of the vehicle; 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 sprayed into the exhaust pipe; During the communication process, obtaining a third pressure value collected by the pressure sensor; Based on the third pressure value and the ambient pressure value, performing the pressure abnormality detection on the urea system to determine whether the pressure abnormality of 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 in the urea system still exists, the urea system is controlled to perform gas exchange with the external environment.

7. The fault diagnosis method of the urea system according to any one of claims 1 to 6, 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 the 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.

8. A fault diagnosis device for a urea system, characterized in that: The urea system includes a pressure sensor, and the pressure sensor is used to detect the internal pressure of the urea system. The device includes: an acquisition module, configured to acquire, in response to the vehicle being powered on, 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 used 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 the external environment in the presence of the abnormal pressure, 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; The determination module is used to determine a faulty component of the urea system from a plurality of components included in the urea system based on the abnormal pressure detection result.

9. A urea system, characterized in that: The urea system is communicatively connected with 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 7; 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; wherein the sealing cover is provided with a cover plate with an electric control switch, and the cover plate is used to adjust the connection or disconnection between the urea system and the external environment, and the electric control switch is controlled by the urea control unit.

10. A vehicle, characterized in that: The vehicle comprises a fault diagnosis unit, and the fault diagnosis unit is used to execute the fault diagnosis method of the urea system according to any one of claims 1 to 7.

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