Gear control method for hydraulic parking

Abstract

The invention relates to the field of automobile transmission control, in particular to a gear control method for hydraulic parking. According to the method, multiple threshold values are set, and two paths for entering the factory modes are provided, so that in the vehicle production process, the requirement for production line passing of a main engine factory can be met, the safety of the whole vehicle can be fully guaranteed, and the vehicle adopting hydraulic parking can also be normally moved in the non-ignition state; and on the other hand, the requirement that the vehicle is kept at the non-P gear under the non-ignition condition when the vehicle is repaired after leaving a factory can be met.

Description

Technical Field

[0001] The present invention relates to the field of automobile transmission control, and in particular to a gear position control method for hydraulic parking. Background Art

[0002] Rain testing is a crucial step in the OEM vehicle production process. Its purpose is to verify the vehicle's sealing (e.g., to check for leaks in doors, windows, sunroofs, trunks, etc.). During this test, the vehicle is pulled and pushed slowly through the test area by external equipment, completing the vehicle's sealing inspection.

[0003] As we all know, hydraulic parking systems in ordinary vehicles typically utilize hydraulic devices to achieve the parking brake function. This method of operation is responsive and can complete parking in a very short time, effectively preventing safety hazards such as vehicle rollaway, providing reliable parking assurance, and its operating mechanism is highly efficient and stable. A hydraulic parking system primarily consists of key components such as a hydraulic pump, brake caliper, control valve, and energy storage device. When the vehicle needs to be parked, the hydraulic pump, under the control of the control valve, supplies pressure to the brake caliper. This pressure causes the caliper to quickly and forcefully clamp the brake disc, thereby achieving a stable parking position. Therefore, to enhance vehicle safety and reliability, hydraulic parking systems rely entirely on hydraulic pressure to execute parking and unparking actions during vehicle use. (This means that hydraulic parking systems utilize a hydraulic mechanism to perform parking, and this hydraulic mechanism requires engine speed to generate pressure, which in turn drives the mechanism to generate pressure.)

[0004] However, in traditional gear control designs, hydraulic parking systems communicate and are controlled via the CAN network. For vehicle safety reasons, the parking mechanism is closely linked to the vehicle's operating state during vehicle design. Specifically, in the off-gear state, it is generally assumed that the vehicle does not need to be driven. To prevent accidents caused by accidental vehicle movement due to misoperation, the vehicle's gear cannot be shifted out of P. In other words, in the off-gear state, the vehicle's CAN network has no signal, and the parking mechanism will not release pressure. Therefore, manually releasing the parking mechanism to move the vehicle when the ignition is off is usually required. If the parking mechanism is not manually released while the vehicle is in P, even if the vehicle is towed or pushed by external equipment, the forced movement of the vehicle could damage the transmission locking mechanism.

[0005] However, during the actual rain line test, it was found that manually releasing the parking mechanism to move the vehicle had the following disadvantages: ① Complex and inefficient operation: Manually releasing the parking mechanism requires considerable time and effort, significantly reducing efficiency compared to normal vehicle operation. During vehicle production, rain-testing is typically performed in batches. This inefficiency can impact the overall production schedule, increasing production costs.

[0006] ② Damage to vehicle components: During vehicle production or even vehicle repair, manually releasing the parking mechanism may cause additional wear or damage to the parking system components. For example, forcibly releasing the mechanical parking brake may cause the parking brake cable to deform or break, or cause excessive wear on the brake pads; for electronic parking brakes, improper manual release operations may damage the electronic control components or motors, affecting the normal function of the parking system. In addition, when the vehicle is moved without the ignition, the vehicle's steering, suspension and other systems may be placed in an abnormal stress state. During normal driving, these systems bear force with the engine running and the various vehicle components working together. However, when manually releasing the parking mechanism to move the vehicle, these components may be subjected to uneven force. Long-term or frequent operation may cause components to deform and loosen, affecting the vehicle's handling performance and driving stability.

[0007] Therefore, how to meet the production line requirements of the OEM and the needs of vehicle repair while taking into account the safety of the entire vehicle, ensuring that the vehicle can be moved safely and smoothly during rain testing, while avoiding unnecessary burden or damage to the gearbox and other vehicle systems, and allowing the vehicle to pass the inspection area smoothly under the action of external forces has always been a problem that needs to be solved urgently by technical personnel in this field. Summary of the Invention

[0008] The purpose of the present invention is to address the corresponding deficiencies in the existing technology and provide a gear control method for hydraulic parking. The present invention sets multiple thresholds and provides two paths for automatically entering the factory mode. On the one hand, it can meet the production line requirements of the main manufacturer during the vehicle production process, and fully ensure the safety of the entire vehicle, so that vehicles using hydraulic parking can move normally even when the ignition is not on; on the other hand, it can also meet the need to keep the vehicle in a non-P gear (for example, keep it in N gear) when the ignition is not on when the vehicle is returned for repair after leaving the factory.

[0009] The purpose of the present invention is to adopt the following scheme to achieve: A gear position control method for hydraulic parking comprises the following steps: 1) Set the first mileage threshold and the second mileage threshold to determine the path for the vehicle to enter factory mode and whether the vehicle has exited factory mode; 2) During the rain line detection process, the mileage displayed on the instrument panel when the vehicle is first powered on is compared with the first mileage threshold to determine whether the current vehicle is a "repair vehicle": ① If the mileage on the instrument panel is less than the first mileage threshold, the vehicle is not a "repair vehicle" and the first path is selected to enter factory mode; ② If the mileage on the instrument panel is ≥ the first mileage threshold, the vehicle is a "repair vehicle" and the second path is selected to enter factory mode; 3) Monitoring the current instrument panel mileage, comparing the current instrument panel mileage with a first mileage threshold value or a second mileage threshold value, and determining when the vehicle exits the factory mode.

[0010] Preferably, the factory mode is that the current gear of the vehicle remains in a non-P gear state when the ignition is not turned on.

[0011] Preferably, in step 2), if the first path is selected to enter the factory mode, the current gear of the vehicle is automatically maintained in a non-P gear state without ignition.

[0012] Preferably, a time threshold and a vehicle speed threshold are also provided. In step 2), if the second path is selected to enter the factory mode, the current instrument panel mileage needs to be compared with a third mileage threshold X before entering the factory mode. If the third mileage threshold X ≤ the current instrument panel mileage ≤ the second mileage threshold, the vehicle enters the factory mode.

[0013] Preferably, the third mileage threshold X is determined as follows: (1) Detect the automatic gear status, brake pedal status, vehicle speed, and whether the shift handle is pulled down to the second level within the time threshold; (2) If the relationship between the vehicle's "automatic gear status", "brake pedal status", "whether the shift handle is pulled down to the second level", and "vehicle speed" and the vehicle speed threshold is within the time threshold, and the following conditions are met at the same time, then the current instrument panel mileage is recorded and stored as the third mileage threshold X: ① Pull the shift handle down to the second level; ② The automatic gear position is D; ③ The brake pedal is pressed down; ④ Vehicle speed ≤ speed threshold.

[0014] Preferably, in step 3), determining the timing for the vehicle to exit the factory mode specifically includes: 3-1) If the vehicle selects the first path to enter factory mode, the current instrument panel mileage is compared with the first mileage threshold value again to determine whether the vehicle has exited factory mode. ① If the current instrument panel mileage is ≥ the first mileage threshold, the vehicle exits factory mode; ② If the current instrument panel mileage is less than the first mileage threshold, the vehicle remains in factory mode; 3-2) When the vehicle selects the second path to enter factory mode, the current instrument panel mileage is compared with the second mileage threshold value, and the vehicle is judged to exit factory mode based on the relationship between the current instrument panel mileage and the second mileage threshold value: ① If the current instrument panel mileage is greater than the second mileage threshold, the vehicle exits factory mode; ② If the current instrument panel mileage is ≤ the second mileage threshold, the vehicle remains in factory mode.

[0015] Preferably, in step 2), after the vehicle enters factory mode, the TCU executes the following strategies: ① The door signal is "closed"; ② When the vehicle's automatic gear status signal is "N gear", the engine speed is less than the engine speed threshold, and the vehicle's automatic gear status signal remains unchanged.

[0016] Preferably, in step 3-2), the second mileage threshold is the sum of the third mileage threshold X and Y, and Y is a calibration value.

[0017] The present invention has the following beneficial effects: A gear position control method for hydraulic parking comprises the following steps: 1) Set the first mileage threshold and the second mileage threshold to determine the path for the vehicle to enter factory mode and whether the vehicle has exited factory mode; 2) During the rain line detection process, the mileage displayed on the instrument panel when the vehicle is first powered on is compared with the first mileage threshold to determine whether the current vehicle is a "repair vehicle": ① If the mileage on the instrument panel is less than the first mileage threshold, the vehicle is not a "repair vehicle" and the first path is selected to enter factory mode; ② If the mileage on the instrument panel is ≥ the first mileage threshold, the vehicle is a "repair vehicle" and the second path is selected to enter factory mode; The present invention distinguishes between different states of vehicles (new vehicles before leaving the factory and vehicles returned for repair after leaving the factory) by setting a first mileage threshold, which can specifically meet the needs of different scenarios and improve the flexibility and practicality of the factory model.

[0018] 3) Monitoring the current instrument panel mileage, comparing the current instrument panel mileage with a first mileage threshold value or a second mileage threshold value, and determining when the vehicle exits the factory mode.

[0019] This invention establishes two effective paths to factory mode by setting multiple thresholds and monitoring the mileage on the vehicle dashboard in real time, depending on the vehicle's lifecycle stage. On the one hand, this system can meet the requirements of rain-testing during vehicle production while fully ensuring vehicle safety, enabling vehicles with hydraulic parking brakes to be maneuvered even without the ignition engaged. On the other hand, it can also meet the requirement of maintaining a non-P gear when a vehicle is returned for repair after leaving the factory, significantly facilitating repairs and improving the efficiency and quality of repair work.

[0020] Preferably, the factory mode is that the current gear of the vehicle remains in a non-P gear state when the ignition is not turned on.

[0021] Preferably, in step 2), if the first path is selected to enter the factory mode, the current gear of the vehicle is automatically maintained in a non-P gear state without ignition.

[0022] Preferably, a time threshold and a vehicle speed threshold are also provided. In step 2), if the second path is selected to enter the factory mode, the current instrument panel mileage needs to be compared with a third mileage threshold X before entering the factory mode. If the third mileage threshold X ≤ the current instrument panel mileage ≤ the second mileage threshold, the vehicle enters the factory mode.

[0023] Preferably, the third mileage threshold X is determined as follows: (1) Detect the automatic gear status, brake pedal status, vehicle speed, and whether the shift handle is pulled down to the second level within the time threshold; (2) If the relationship between the vehicle's "automatic gear status", "brake pedal status", "whether the shift handle is pulled down to the second level", and "vehicle speed" and the vehicle speed threshold is within the time threshold, and the following conditions are met at the same time, then the current instrument panel mileage is recorded and stored as the third mileage threshold X: ① Pull the shift handle down to the second level; ② The automatic gear position is D; ③ The brake pedal is pressed down; ④ Vehicle speed ≤ speed threshold.

[0024] Based on the differences in the paths vehicles take to enter Factory Mode, this invention specifically sets the conditions for different vehicles to enter Factory Mode, effectively ensuring the efficiency of the vehicle production and inspection process and improving production efficiency. Furthermore, the second path comprehensively considers multiple conditions to make a judgment, capable of comprehensively and accurately assessing whether a vehicle is suitable for entering Factory Mode. This effectively prevents vehicles from mistakenly entering Factory Mode due to misjudgment while driving, thereby preventing interference with normal user use.

[0025] Preferably, in step 3), determining the timing for the vehicle to exit the factory mode specifically includes: 3-1) If the vehicle selects the first path to enter factory mode, the current instrument panel mileage is compared with the first mileage threshold value again to determine whether the vehicle has exited factory mode. ① If the current instrument panel mileage is ≥ the first mileage threshold, the vehicle exits factory mode; ② If the current instrument panel mileage is less than the first mileage threshold, the vehicle remains in factory mode; 3-2) When the vehicle selects the second path to enter factory mode, the current instrument panel mileage is compared with the second mileage threshold value, and the vehicle is judged to exit factory mode based on the relationship between the current instrument panel mileage and the second mileage threshold value: ① If the current instrument panel mileage is greater than the second mileage threshold, the vehicle exits factory mode; ② If the current instrument panel mileage is ≤ the second mileage threshold, the vehicle remains in factory mode.

[0026] By setting reasonable first and second mileage thresholds, this invention provides vehicles with sufficient time and mileage to fully and smoothly complete all scheduled inspections or maintenance tasks. This effectively prevents premature vehicle exit from factory mode, preventing inspections or maintenance from being completed and requiring rework, thereby significantly improving efficiency.

[0027] Preferably, in step 2), after the vehicle enters factory mode, the TCU executes the following strategies: ① The door signal is "closed"; ② When the vehicle's automatic gear status signal is "N gear", the engine speed is less than the engine speed threshold, and the vehicle's automatic gear status signal remains unchanged.

[0028] The present invention controls the TCU to execute relevant strategies after the vehicle enters factory mode. This ensures that the vehicle's automatic gear signal remains in N gear even if the vehicle doors are frequently opened and closed or the gear is accidentally changed during inspection or maintenance, thereby ensuring the safety of the vehicle inspection or maintenance process.

[0029] Preferably, in step 3-2), the second mileage threshold is the sum of the third mileage threshold X and Y, and Y is a calibration value determined through a calibration experiment.

[0030] Preferably, an error judgment threshold is further provided for clearing the recorded and stored current instrument panel mileage, i.e., the third mileage threshold X, after exiting the factory mode when the instrument panel mileage display is significantly smaller.

[0031] The present invention sets an error judgment threshold and, after exiting the factory mode, monitors the instrument panel mileage in real time and compares it with the set error judgment threshold, thereby preventing the vehicle from mistakenly entering the factory mode while driving when the vehicle instrument panel malfunctions or the instrument panel mileage decreases due to maintenance, thereby affecting the normal driving of the vehicle.

[0032] Glossary Main vehicle manufacturer: In the field of vehicle production, it usually refers to an automobile manufacturer, that is, a manufacturer responsible for assembling various automobile parts into a complete automobile product.

[0033] NVM: In the present invention, non-volatile memory (NVM) is a computer memory that can retain its stored data even when there is no power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0035] A gear position control method for hydraulic parking comprises the following steps: 1) Set the first mileage threshold and the second mileage threshold to determine the path for the vehicle to enter factory mode and whether the vehicle has exited factory mode; 2) During the rain line detection process, the mileage displayed on the instrument panel when the vehicle is first powered on is compared with the first mileage threshold to determine whether the current vehicle is a "repair vehicle": ① If the mileage on the instrument panel is less than the first mileage threshold, the vehicle is not a "repair vehicle" and the first path is selected to enter factory mode, keeping the vehicle's current gear in a non-P gear without the ignition on; ② If the mileage on the instrument panel is ≥ the first mileage threshold, the vehicle is considered a "repair vehicle" and the second path is selected to enter factory mode, keeping the vehicle's current gear in a non-P gear without the ignition on. Typically, a time threshold and a vehicle speed threshold are also provided. In step 2), if the second path is selected to enter factory mode, the current instrument panel mileage needs to be compared with a third mileage threshold X before entering factory mode. If the third mileage threshold X ≤ the current instrument panel mileage ≤ the second mileage threshold, the vehicle enters factory mode.

[0036] The third mileage threshold X is determined as follows: (1) Detect the automatic gear status, brake pedal status, vehicle speed, and whether the shift handle is pulled down to the second level within the time threshold; (2) If the relationship between the vehicle's "automatic gear status", "brake pedal status", "whether the shift handle is pulled down to the second level", and "vehicle speed" and the vehicle speed threshold is within the time threshold, and the following conditions are met at the same time, then the current instrument panel mileage is recorded and stored as the third mileage threshold X: ① Pull the shift handle down to the second level; ② The automatic gear position is D; ③ The brake pedal is pressed down; ④ Vehicle speed ≤ speed threshold.

[0037] It is worth noting that after the vehicle enters factory mode, the TCU also needs to execute the following strategies: ① The door signal is "closed"; ② When the vehicle's automatic gear status signal is "N gear", the engine speed is less than the engine speed threshold, and the vehicle's automatic gear status signal remains unchanged.

[0038] 3) Monitor the current instrument panel mileage and compare the current instrument panel mileage with the first mileage threshold or the second mileage threshold to determine when the vehicle should exit factory mode, including: 3-1) If the vehicle selects the first path to enter factory mode, the current instrument panel mileage is compared with the first mileage threshold value again to determine whether the vehicle has exited factory mode. ① If the current instrument panel mileage is ≥ the first mileage threshold, the vehicle exits factory mode; ② If the current instrument panel mileage is less than the first mileage threshold, the vehicle remains in factory mode; 3-2) When the vehicle selects the second path to enter factory mode, the current instrument panel mileage is compared with the second mileage threshold value, and the vehicle is judged to exit factory mode based on the relationship between the current instrument panel mileage and the second mileage threshold value: ① If the current instrument panel mileage is greater than the second mileage threshold, the vehicle exits factory mode; ② If the current instrument panel mileage is ≤ the second mileage threshold, the vehicle remains in factory mode.

[0039] According to the above method, an embodiment is made as follows: a gear control method for hydraulic parking includes the following steps: Figure 1 As shown: 1) Set a first mileage threshold to determine the path a vehicle takes to enter and exit Factory Mode. During vehicle production, the mileage required to fully cover each stage of the production line must be determined based on the specific process flow of the OEM's production line. This ensures that the vehicle can stably shift into a non-P gear without the ignition on the production line. In this embodiment, the first mileage threshold is set to 10 km.

[0040] 2) When powered on, the TCU receives the mileage displayed on the dashboard of the vehicle and compares it with the first mileage threshold to determine the path the vehicle should take to enter factory mode. The specific method is as follows: ① If the mileage on the instrument panel is less than the first mileage threshold, the vehicle selects the first path to enter factory mode; ② If the mileage on the instrument panel is ≥ the first mileage threshold, the vehicle selects the second path to enter factory mode.

[0041] After the vehicle is powered on, the instrument panel will send the mileage signal (BCM_2_TotalOdometer_Km) to the TCU according to the set 10ms period.

[0042] Based on the path the vehicle chooses to enter factory mode, the specific steps to further determine whether the vehicle has entered factory mode are as follows: 2-1) If the vehicle selects the first path to enter factory mode, it will enter factory mode directly; Entering Factory Mode via the first path ensures that the vehicle remains in N, rather than P, even when the ignition is turned off, while on the OEM production line. Since the vehicle is still in production and not yet officially in use, entering Factory Mode requires only a simple mileage check (comparison with the first mileage threshold), simplifying operation and effectively improving production efficiency.

[0043] 2-2) If the vehicle selects the second path to enter factory mode, the specific steps for determining whether the vehicle has entered factory mode are as follows: 2-2-1) A time threshold is set, and within this time threshold, the automatic gear position, brake pedal status, vehicle speed, and whether the shift handle is pulled down to the last two positions are detected; 2-2-2) Set the vehicle speed threshold to determine whether the vehicle enters factory mode; 2-2-3) Within the time threshold, the specific steps for determining whether the vehicle has entered factory mode are as follows based on the vehicle's "automatic gear status," "brake pedal status," "whether the shift handle is pulled down to the second position," and the relationship between the "vehicle speed" and the vehicle speed threshold detected in step 2-2-1): (1) If the vehicle's "automatic gear status", "brake pedal status", "whether the shift handle is pulled down to the second level", and the relationship between the "vehicle speed" and the vehicle speed threshold all meet the following conditions within the time threshold, the current instrument panel mileage is recorded and stored as the third mileage threshold X: Pull the shift handle down to the second level; ② The automatic gear position is D; ③ The brake pedal is pressed down; ④ Vehicle speed ≤ speed threshold; On the contrary, if the vehicle does not meet the above conditions at the same time, the current instrument panel mileage will not be recorded and stored as the third mileage threshold X (in this embodiment, the third mileage threshold X is stored in the vehicle's NVM), and the process returns to the previous determination step: the vehicle selects the path to enter the factory mode.

[0044] In this embodiment, the time threshold is 10 seconds, and the speed threshold is 3 meters per second. By analyzing vehicle design logic, collecting driving behavior data, considering actual road scenarios, and adhering to regulatory standards, the system uses operating conditions that would not be triggered under normal vehicle driving as judgment criteria. This effectively prevents users from accidentally entering factory mode during use, affecting normal driving, while also ensuring safety when entering factory mode.

[0045] ⑵ A second mileage threshold is also provided, and the current instrument panel mileage is compared with a third mileage threshold X. If the third mileage threshold X ≤ the current instrument mileage ≤ the second mileage threshold, the vehicle enters factory mode.

[0046] In the present invention, the second mileage threshold = the third mileage threshold X + Y, where Y is a calibrated value. The design considerations for the vehicle entering factory mode via the second route are primarily based on the practical needs of vehicle repair scenarios. When a vehicle is under repair, it is often necessary to maintain a non-P gear without the ignition, but such operations generally do not require the vehicle to move long distances.

[0047] To ensure that the vehicle can successfully exit Factory Mode after maintenance is completed while avoiding any potential impact on subsequent normal driving, the present invention specifically sets a second mileage threshold as one of the key criteria for determining whether the vehicle enters Factory Mode. In this embodiment of the present invention, the value of Y is 2 km.

[0048] 3) Based on the judgment result of step 2), after the vehicle enters factory mode, the TCU executes the following strategies: ① The door signal is "closed"; For safety reasons, some OEMs automatically shift the vehicle to P gear when the door signal is detected as "open." Therefore, to meet the specific debugging and testing requirements of factory production processes and vehicle repairs, this invention ensures that even with frequent door openings, the vehicle will not suddenly shift from N to P gear, thereby disrupting the production process and the smooth progress of vehicle repairs.

[0049] ② When the vehicle's automatic gear status signal is "N gear", the engine speed is less than the engine speed threshold, and the vehicle's automatic gear status signal remains unchanged.

[0050] Most OEMs have set up the logic of "normally shutting down and entering P gear" in order to prevent the vehicle from moving due to external forces or other factors after the engine is shut down. Therefore, when the engine speed of the vehicle is less than a specific engine speed (i.e., the engine speed threshold in the present invention), the automatic gear state of the vehicle will jump to P gear, thereby realizing the parking function. However, in order to meet the special needs of the factory production process or vehicle repair (for example, when testing the vehicle's electrical system, it may be necessary to frequently shut down and ignite the engine to check the electrical performance under different states), the present invention specifically sets the vehicle to enter the factory mode. Regardless of whether the vehicle is shut down or powered on and ignited again, when the vehicle's automatic gear state signal is "N gear", the engine speed is less than the engine speed threshold, and the automatic gear state signal still remains in "N gear". In this embodiment, the engine speed threshold is 50 rpm. And the engine speed threshold is a calibrated value.

[0051] After the vehicle enters factory mode, the current instrument panel mileage is monitored and compared with the first mileage threshold or the second mileage threshold value based on the path the vehicle took to enter factory mode. The specific steps for determining whether to exit factory mode are as follows: 3-1) When the vehicle selects the first path to enter factory mode, the current instrument panel mileage is compared with the first mileage threshold value again, and the vehicle is judged to exit factory mode based on the relationship between the current instrument panel mileage and the first mileage threshold value: ① If the current instrument panel mileage is ≥ the first mileage threshold, the vehicle exits factory mode; ② If the current instrument panel mileage is less than the first mileage threshold, the vehicle remains in factory mode; When the vehicle is completed on the production line of the OEM, it exits the factory mode and can be subsequently sold and used normally.

[0052] 3-2) When the vehicle selects the second path to enter factory mode, the current instrument panel mileage is compared with the second mileage threshold value, and the vehicle is judged to exit factory mode based on the relationship between the current instrument panel mileage and the second mileage threshold value: ① If the current instrument panel mileage is greater than the second mileage threshold, the vehicle exits factory mode; ② If the current instrument panel mileage is ≤ the second mileage threshold, the vehicle remains in factory mode.

[0053] In this embodiment, an error judgment threshold is further provided, which is used to clear the recorded and stored current instrument panel mileage, i.e., the third mileage threshold X, after exiting the factory mode when the instrument panel mileage display is significantly smaller.

[0054] Specifically, if the instrument panel mileage is less than the error determination threshold, the third mileage threshold X is reset to zero. The error determination threshold is calculated as follows: third mileage threshold X minus a set value, where the set value is 5. If the instrument panel mileage decreases or clears due to a malfunction or a replacement of the instrument panel during vehicle repair, there is a high probability that during normal vehicle operation, when the instrument panel mileage increases again to the third mileage threshold X stored in the NVM, the vehicle will enter factory mode without a request, thus affecting normal vehicle operation. Therefore, after exiting factory mode, if the instrument panel mileage is less than the third mileage threshold X minus 5, the instrument panel mileage stored in the NVM is reset to zero.

[0055] In this way, according to the above method, when the vehicle passes the rain line detection process, the current gear will be automatically changed from P gear to N gear (neutral) without ignition according to the current vehicle status, so that the vehicle can pass the detection area safely and smoothly under the action of external force, meeting the production line requirements of the OEM or the needs of vehicle repair, without causing unnecessary burden or damage to the gearbox and other vehicle systems.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications made to the present invention by those skilled in the art without departing from the spirit of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A gear control method for hydraulic parking, characterized in that: The following steps are involved: 1) Set the first mileage threshold and the second mileage threshold to determine the path for the vehicle to enter factory mode and whether the vehicle has exited factory mode; 2) During the rain line detection process, the mileage displayed on the instrument panel when the vehicle is first powered on is compared with the first mileage threshold to determine whether the current vehicle is a "repair vehicle": ① If the mileage on the instrument panel is less than the first mileage threshold, the vehicle is not a "repair vehicle" and the first path is selected to enter factory mode; ② If the mileage on the instrument panel is ≥ the first mileage threshold, the vehicle is a "repair vehicle" and the second path is selected to enter factory mode; 3) Monitoring the current instrument panel mileage, comparing the current instrument panel mileage with a first mileage threshold value or a second mileage threshold value, and determining when the vehicle exits the factory mode.

2. A gear position control method for hydraulic parking according to claim 1, characterized in that: The factory mode is that the current gear of the vehicle remains in a non-P gear state when the ignition is not turned on.

3. The gear position control method for hydraulic parking according to claim 1, characterized in that: In step 2), if the first path is selected to enter the factory mode, the current gear of the vehicle is automatically kept in a non-P gear state without ignition.

4. The gear position control method for hydraulic parking according to claim 1, characterized in that: A time threshold and a vehicle speed threshold are also provided. In step 2), if the second path is selected to enter the factory mode, the current instrument panel mileage needs to be compared with a third mileage threshold X before entering the factory mode. If the third mileage threshold X ≤ the current instrument panel mileage ≤ the second mileage threshold, the vehicle enters the factory mode.

5. The gear position control method for hydraulic parking according to claim 4, characterized in that: The third mileage threshold X is determined as follows: (1) Detect the automatic gear status, brake pedal status, vehicle speed, and whether the shift handle is pulled down to the second level within the time threshold; (2) If the relationship between the vehicle's "automatic gear status", "brake pedal status", "whether the shift handle is pulled down to the second position", and "vehicle speed" and the vehicle speed threshold is within the time threshold, and the following conditions are met at the same time, then the current instrument panel mileage is recorded and stored as the third mileage threshold X: ① Pull the shift handle down to the second level; ② The automatic gear position is D; ③ The brake pedal is pressed down; ④ Vehicle speed ≤ speed threshold.

6. The gear position control method for hydraulic parking according to claim 1, characterized in that: In step 3), the timing for the vehicle to exit factory mode is determined, including: 3-1) If the vehicle selects the first path to enter factory mode, the current instrument panel mileage is compared with the first mileage threshold value again to determine whether the vehicle has exited factory mode. ① If the current instrument panel mileage is ≥ the first mileage threshold, the vehicle exits factory mode; ② If the current instrument panel mileage is less than the first mileage threshold, the vehicle remains in factory mode; 3-2) When the vehicle selects the second path to enter factory mode, the current instrument panel mileage is compared with the second mileage threshold value, and the vehicle is judged to exit factory mode based on the relationship between the current instrument panel mileage and the second mileage threshold value: ① If the current instrument panel mileage is greater than the second mileage threshold, the vehicle exits factory mode; ② If the current instrument panel mileage is ≤ the second mileage threshold, the vehicle remains in factory mode.

7. The gear position control method for hydraulic parking according to claim 1, characterized in that: In step 2), after the vehicle enters factory mode, the TCU executes the following strategies: ① The door signal is "closed"; ② When the vehicle's automatic gear status signal is "N gear", the engine speed is less than the engine speed threshold, and the vehicle's automatic gear status signal remains unchanged.

8. The gear position control method for hydraulic parking according to claim 6, characterized in that: In step 3-2), the second mileage threshold is the sum of the third mileage threshold X and Y, where Y is a calibration value.

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