OBD Speed Limiting Method in the Fault Mode of Vehicle Speed Sensor

Abstract

The present invention discloses an OBD vehicle speed limiting method in the failure mode of a vehicle speed sensor, which includes: determining whether the whole vehicle is an AMT model. If the whole vehicle is an AMT model, then determining whether the severe driving performance limitation system is activated. If it has been activated, determining whether the vehicle speed signal is normal. If the vehicle speed signal is abnormal, the vehicle speed is limited by the maximum engine speed at each gear calibrated in advance. Thereby, the OBD vehicle speed limiting method in the failure mode of the vehicle speed sensor of the present invention can achieve OBD vehicle speed limiting in the failure mode of the vehicle speed sensor. Even if the vehicle speed sensor fails, the OBD vehicle speed limiting strategy can still be activated, making up for the loopholes where OBD vehicle speed limiting cannot be activated in some scenarios.

Description

Technical Field

[0001] The present invention relates to the field of vehicle control technology, and particularly to an OBD vehicle speed limiting method in the failure mode of a vehicle speed sensor. Background Art

[0002] In the national VI diesel engine, a new driver performance limiting system is added. According to the requirements of GB17691-2018 "Limits and Measurement Methods for Emissions from Heavy-Duty Diesel Vehicles", after serious faults such as an empty urea tank, low urea concentration, and low SCR efficiency are activated, even if the vehicle speed sensor is disconnected, the vehicle speed signal can be quickly judged through engine speed, torque, gear signal, etc. When the vehicle speed signal is judged to be unreasonable, the vehicle speed is limited by the maximum engine speed at each gear calibrated in advance, so as to achieve OBD vehicle speed limiting in the failure mode of the vehicle speed sensor. Even if the vehicle speed sensor fails, the OBD vehicle speed limiting strategy can still be activated to urge the driver to repair the vehicle in time.

[0003] In the existing technical solution, OBD vehicle speed limiting is carried out through PID control between parameters such as the current vehicle speed and the target vehicle speed. When the vehicle speed signal is tampered with, first, the vehicle speed signal is diagnosed through engine speed, output torque, clutch signal, and neutral gear signal. After reporting a vehicle speed rationality fault, the torque is limited by activating the vehicle speed rationality fault. However, the OBD vehicle speed limiting function cannot be activated, and only severe torque limitation can be used to strengthen the limiting effect, limiting it to less than 50%.

[0004] In the existing technical solution, there are the following disadvantages:

[0005] 1. A physical neutral gear switch must be installed to complete the diagnosis of vehicle speed rationality, and then severe torque limitation is performed through the fault.

[0006] 2. Only the engine torque can be further limited, and the vehicle speed cannot be limited. In some scenarios, there is no urging effect on the driver, and the limiting effect required by the regulations cannot be achieved.

[0007] 3. The limiting effect cannot be activated until the diagnosis of the vehicle speed signal is completed, and severe driving performance limitation cannot be activated in real time.

[0008] The information disclosed in this background art section is only intended to enhance the overall understanding of the present invention and should not be regarded as an admission or any form of suggestion that this information constitutes prior art already known to those of ordinary skill in the art. Summary of the Invention

[0009] The object of the present invention is to provide an OBD vehicle speed limiting method in the case of a vehicle speed sensor failure mode, which can achieve OBD vehicle speed limiting in the case of a vehicle speed sensor failure mode. Even if the vehicle speed sensor fails, the OBD vehicle speed limiting strategy can still be activated, filling the loophole that the OBD vehicle speed limiting cannot be activated in some scenarios.

[0010] To achieve the above object, the present invention provides an OBD vehicle speed limiting method in the case of a vehicle speed sensor failure mode, including: determining whether the whole vehicle is an AMT model. If the whole vehicle is an AMT model, then determining whether the severe driving performance limitation system is activated. If it has been activated, determining whether the vehicle speed signal is normal. If the vehicle speed signal is abnormal, the vehicle speed is limited by the maximum engine speed at each gear calibrated in advance.

[0011] In an embodiment of the present invention, if the vehicle speed signal is normal, the vehicle speed is limited by the PID control between the actual vehicle speed and the target vehicle speed.

[0012] In an embodiment of the present invention, determining whether the vehicle speed signal is normal specifically judges the vehicle speed signal through the engine speed, torque, and gear signal.

[0013] In an embodiment of the present invention, when the faults of empty urea tank, low urea concentration, and low SCR efficiency are activated, and the faults are not processed and continuously activated for a preset time, the severe driving performance limitation system is activated.

[0014] Compared with the prior art, the OBD vehicle speed limiting method in the case of a vehicle speed sensor failure mode according to the present invention has the following beneficial effects:

[0015] 1. Obtain the gear signal through the ETC2 message sent by the gearbox, and then combine it with the engine speed signal to judge whether the vehicle speed signal is normal in real time, greatly improving the diagnosis efficiency. The vehicle speed rationality fault can be diagnosed in only 10 s;

[0016] 2. After the severe driving limitation system is activated, the maximum vehicle speed at each gear is limited by pre-developed OBD calibration to ensure that the maximum vehicle speed ≤ 20 km / h, ensuring that it has a supervisory effect on the driver in various scenarios;

[0017] 3. There is no need to install a neutral gear switch, and the gear signal is obtained by using the ETC2 message sent by the gearbox, reducing the cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a flow schematic diagram of the OBD vehicle speed limiting method in the case of a vehicle speed sensor failure mode according to an embodiment of the present invention;

[0019] Figure 2It is a schematic logical block diagram of the OBD vehicle speed limit method in the vehicle speed sensor failure mode according to an embodiment of the present invention. Detailed Embodiment

[0020] The following will describe in detail the specific embodiments of the present invention with reference to the accompanying drawings. It should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0021] Unless otherwise clearly stated, in the whole specification and claims, the term "comprise" or its variations such as "comprises" or "including" etc. will be understood to include the stated elements or components, without excluding other elements or other components.

[0022] Figure 1 It is a schematic flowchart of the OBD vehicle speed limit method in the vehicle speed sensor failure mode according to an embodiment of the present invention.

[0023] As Figure 1 shown, an OBD vehicle speed limit method in the vehicle speed sensor failure mode according to a preferred embodiment of the present invention includes: determining whether the whole vehicle is an AMT vehicle model. If the whole vehicle is an AMT vehicle model, then determining whether the severe driving performance limitation system is activated. If it is activated, determining whether the vehicle speed signal is normal. If the vehicle speed signal is not normal, the vehicle speed is limited by the maximum engine speed at each gear calibrated in advance.

[0024] In an embodiment of the present invention, if the vehicle speed signal is normal, the vehicle speed is limited by the PID control between the actual vehicle speed and the target vehicle speed.

[0025] In an embodiment of the present invention, determining whether the vehicle speed signal is normal specifically judges the vehicle speed signal through the engine speed, torque, and gear signal (obtained from the ETC2 message sent by the gearbox).

[0026] In an embodiment of the present invention, when the faults of the urea tank being empty, the urea concentration being low, and the SCR efficiency being low are activated, and the faults are not processed and continuously activated for a preset time, the severe driving performance limitation system is activated.

[0027] In practical applications, when severe faults such as an empty urea tank, low urea concentration, and low SCR efficiency are activated, if the faults are not addressed, after the faults are continuously activated for a certain period of time, the severe driving performance limitation system is activated. If the vehicle speed sensor is disconnected, the vehicle speed signal is quickly judged based on the engine speed and gear signal (obtained from the ETC2 message sent by the transmission). When it is determined that the vehicle speed signal is unreasonable, the vehicle speed is limited by the maximum engine speed at each gear calibrated in advance, thus realizing the OBD vehicle speed limit in the vehicle speed sensor fault mode. Even if the vehicle speed sensor fails, the OBD vehicle speed limit strategy can still be activated, filling the loophole that the OBD vehicle speed limit cannot be activated in some scenarios.

[0028] Figure 2 It is a schematic logical block diagram of the OBD vehicle speed limit method in the vehicle speed sensor fault mode according to an embodiment of the present invention. As Figure 2 shown, first, it is judged whether the whole vehicle is an AMT model. If it is an AMT model, then it is judged whether the severe driving performance limitation system is activated. If it has been activated, then it is judged whether the vehicle speed signal is normal. If it is normal, the vehicle speed is limited by the PID control between the actual vehicle speed and the target vehicle speed. If it is not normal, the vehicle speed rationality fault is diagnosed through the engine speed and gear signal (obtained from the ETC2 message sent by the transmission). By calibrating the failure strategy for the vehicle speed rationality fault, after the fault is reported, the engine speed is limited for each gear respectively, and calibration is carried out in advance to calibrate the maximum vehicle speed for each gear in the fault mode, so as to ensure that the actual vehicle speed is lower than 20 km / h.

[0029] In summary, the OBD vehicle speed limit method in the vehicle speed sensor fault mode of the present invention has the following beneficial effects:

[0030] 1. The gear signal is obtained from the ETC2 message sent by the transmission, and combined with the engine speed signal, it is judged in real time whether the vehicle speed signal is normal, greatly improving the diagnosis efficiency. The vehicle speed rationality fault can be diagnosed in only 10 s;

[0031] 2. After the severe driving limitation system is activated, by carrying out OBD calibration in advance, the maximum vehicle speed for each gear is limited to ensure that the maximum vehicle speed ≤ 20 km / h, ensuring that it has a reminder effect on the driver in all scenarios;

[0032] 3. There is no need to install a neutral switch, and the gear signal is obtained from the ETC2 message sent by the transmission, reducing costs.

[0033] The foregoing description of specific exemplary embodiments of the present invention is for purposes of illustration and exemplification. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many modifications and variations are possible in light of the above teaching. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the invention and its practical applications, so that those skilled in the art can implement and utilize the various different exemplary embodiments of the invention, as well as various different selections and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. An OBD vehicle speed limiting method in the failure mode of the vehicle speed sensor, characterized in that, it includes: judging whether the whole vehicle is an AMT model; if the whole vehicle is an AMT model, judging whether the severe driving performance limitation system is activated; if it is activated, judging whether the vehicle speed signal is normal; if the vehicle speed signal is abnormal, limiting the vehicle speed through the maximum engine speed at each gear calibrated in advance; wherein, if the vehicle speed signal is normal, limiting the vehicle speed through the PID control between the actual vehicle speed and the target vehicle speed; judging whether the vehicle speed signal is normal is specifically judged by the engine speed, torque, and gear signal for the vehicle speed signal.

2. The OBD vehicle speed limiting method in the failure mode of the vehicle speed sensor according to claim 1, characterized in that, after the faults of empty urea tank, low urea concentration, and low SCR efficiency are activated, and the faults are not processed and continuously activated for a preset time, the severe driving performance limitation system is activated.

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