Self-learning method for clutch kp point oil pressure of hybrid vehicle k0

Abstract

The application discloses a kind of hybrid vehicle K0 clutch KP point oil pressure self-learning method, comprising: check the state of vehicle, determine whether vehicle satisfies KP point self-learning condition;Clutch is adjusted to be disconnected state;Maintain motor torque control, stabilize motor speed, keep engine speed idle speed;Constantly fill oil to clutch oil cavity;The speed difference of clutch both ends is monitored, and the average value of clutch oil pressure in the last five sampling periods is calculated as new KP point oil pressure value when the speed difference reaches critical value before this moment.The hybrid vehicle K0 clutch KP point oil pressure self-learning method provided by the application can adjust KP point oil pressure under vehicle stationary and motion conditions, increase self-learning frequency, thereby improve the accuracy of KP point.

Description

Technical Field

[0001] This invention belongs to the field of clutch control technology, specifically relating to a self-learning method for the hydraulic pressure at point KP of the K0 clutch in a hybrid vehicle. Background Technology

[0002] The hybrid system based on the P2 architecture of the vehicle is equipped with an engine, an electric motor, a clutch, a transmission, and a battery pack. The K0 clutch is installed between the electric motor and the engine to transmit and disconnect the engine's power. The clutch generally consists of friction plates, steel plates, a release spring, a piston, and a hydraulic system. When the oil chamber is filled with oil, the piston pushes the release spring, causing the friction plates and steel plates to contact and transmit torque.

[0003] The KISS-POINT point of a clutch refers to the piston pressure required to overcome the release spring and initiate contact between the friction plates and the steel plates. It is also commonly used as the point at which the clutch begins to transmit torque. The hydraulic pressure in the clutch hydraulic control system is called the clutch oil pressure, while the oil pressure corresponding to the KISS-POINT point is called the KP point oil pressure.

[0004] For vehicles with a hybrid architecture, the K0 clutch is a crucial component that assists the drive motor in starting the engine and connects the engine and drive motor to provide driving force for the entire vehicle, significantly impacting the entry into hybrid driving mode. Controlling the KP point during the K0 clutch operation is extremely important; inaccurate KP points lead to torque mismatch between the engine and motor, resulting in poor smoothness and affecting the driver's experience. However, with accumulated mileage, clutch wear and heat can affect the accuracy of the KP point, causing a decline in engine starting function. Therefore, the transmission control unit needs to adjust the hydraulic pressure at the KP point.

[0005] In existing methods for adjusting the KP point hydraulic pressure, adjustments are made solely by monitoring changes in motor torque during the filling process of the clutch hydraulic control system. When the motor torque reaches a threshold, the hydraulic pressure at that moment is taken as the new KP point. This method requires the vehicle to be in a static and stable operating condition. Therefore, it is impossible to adjust the KP point hydraulic pressure during high-speed steady-state operation. This results in the existing transmission control unit being unable to guarantee the adjustment frequency. Furthermore, due to the poor accuracy of the torque sensor, only the hydraulic pressure value at a single moment is used as the self-learning value, leading to poor accuracy of the KP point hydraulic pressure obtained by this method.

[0006] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to provide a self-learning method for the KP point oil pressure of the K0 clutch in a hybrid vehicle, which can adjust the KP point oil pressure of the clutch under high-speed driving conditions.

[0008] To achieve the above objectives, one embodiment of the present invention provides a self-learning method for the hydraulic pressure at the KP point of the K0 clutch in a hybrid vehicle, comprising:

[0009] S1. Check the vehicle's status and determine whether the vehicle meets the self-learning conditions of KP point.

[0010] S2. Adjust the clutch to the disengaged state;

[0011] S3. Maintain motor torque control mode, constant motor speed, engine idle speed, set motor torque threshold and critical value of speed difference between the two ends of the clutch;

[0012] S4. Continuously fill the clutch oil chamber with oil;

[0013] S5. Monitor the motor torque value and the speed difference between the two ends of the clutch. Periodically sample the speed difference and clutch oil pressure. When the speed difference reaches the critical value, read and calculate the average value of the clutch oil pressure of the previous five sampling cycles at this moment.

[0014] In one or more embodiments of the present invention, the self-learning method for the hydraulic pressure at the KP point of the K0 clutch in a hybrid vehicle further includes step S0, which includes: checking whether the vehicle has a self-learning record. If there is a record, self-learning is not performed. If there is no record, the vehicle status is checked to determine whether the vehicle meets the self-learning conditions for the KP point.

[0015] In one or more embodiments of the present invention, step S1 includes: querying the vehicle mileage record to determine whether the vehicle mileage meets the standard; confirming whether the driving load is stable; querying the battery charge to determine whether the battery SOC value is greater than 70%; and confirming whether the lubricating oil temperature in the clutch is normal.

[0016] In one or more embodiments of the present invention, step S2 includes: detecting the clutch status; if the clutch is not disengaged, adjusting the oil pressure of the hydraulic control system connected to the clutch pressure plate to 0, so that the clutch does not transmit torque between the engine and the motor, thereby disengaging the clutch.

[0017] In one or more embodiments of the present invention, step S3 includes: the vehicle controller confirming the current motor torque based on the driver's accelerator and brake pedal status; maintaining the motor torque control mode, keeping the motor speed constant, and keeping the engine idling; setting a motor torque threshold, and confirming the critical value of the speed difference between the two ends of the monitoring clutch based on the threshold.

[0018] In one or more embodiments of the present invention, step S4 includes: supplying hydraulic oil into the oil chamber, continuously increasing the oil pressure, and the piston gradually overcoming the elastic force of the return spring and moving closer to the friction plate under the action of the oil pressure. At the same time, the speed sensor continuously monitors the speed difference between the engine and the motor at both ends of the clutch, and collects and records the oil pressure value and motor torque value during the process.

[0019] In one or more embodiments of the present invention, step S5 includes: during vehicle operation, continuously collecting and processing the speed difference between the two ends of the clutch, and simultaneously recording the motor torque value and the clutch filling pressure value; when the speed difference reaches a critical value, reading and calculating the average value of the clutch oil pressure of the previous five sampling cycles at this moment as the oil pressure value at point KP.

[0020] Compared with existing technologies, this solution takes into account both the motor torque value and the speed difference between the two ends of the clutch, and selects the average oil pressure over multiple sampling periods as the KP point oil pressure, resulting in higher data accuracy. At the same time, it supports self-learning of the vehicle under high-speed motion conditions, increases the frequency of self-learning, and changes the limitation of existing self-learning methods that can only be performed under static conditions. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a flowchart of a self-learning method for the hydraulic pressure at the KP point of the K0 clutch in a hybrid vehicle according to an embodiment of the present invention.

[0023] Figure 2 This is an architectural diagram of a vehicle hybrid system according to an embodiment of the present invention;

[0024] Figure 3 This is a system control diagram of a self-learning method for the hydraulic pressure at the KP point of the K0 clutch in a hybrid vehicle according to an embodiment of the present invention.

[0025] Figure 4 This is a schematic diagram illustrating the change in motor torque according to one embodiment of the present invention;

[0026] Figure 5 This is a schematic diagram illustrating the changes in motor speed and engine speed according to an embodiment of the present invention;

[0027] Figure 6 This is a schematic diagram of the oil pressure sampling process according to one embodiment of the present invention. Detailed Implementation

[0028] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0029] like Figures 1-6 As shown in the embodiment of the present invention, the self-learning method for the hydraulic pressure at clutch KP point K0 in a hybrid vehicle includes steps S0 to S5:

[0030] In step S0, check if the vehicle has a self-learning record of adjusting the KP point hydraulic pressure. If there is a record, it means that the vehicle has already adjusted the KP point hydraulic pressure during this trip, and a second adjustment will not be performed. If there is no record, check the vehicle's status to determine if the vehicle meets the KP point self-learning conditions and whether the KP point hydraulic pressure needs to be adjusted.

[0031] In step S1, the vehicle's status is checked.

[0032] Specifically, checking the vehicle's condition may include: checking the vehicle's mileage record to determine if the mileage meets the target; confirming the engine and motor speeds to determine if they are sufficient to maintain stable driving load; checking the battery charge level to determine if the battery's State of Charge (SOC) is greater than a predetermined value, such as 70%; and confirming that the clutch lubricating oil temperature is normal. Step S2 can only be performed if the vehicle mileage, engine and motor speeds, battery SOC, and clutch oil temperature all meet the requirements. If all the above requirements are not met, the clutch KP point oil pressure will not be adjusted.

[0033] In step S2, the clutch is adjusted to the disengaged state.

[0034] Specifically, the clutch status is detected. If the clutch is not disengaged, the oil pressure of the hydraulic control system connected to the clutch pressure plate is adjusted to 0, the clutch plate is moved away from the engine flywheel, and the clutch does not transmit torque between the engine and the motor, so that the clutch is in the disengaged state.

[0035] In step S3, the motor torque control mode is maintained, the motor speed is constant, the engine is idling, and the motor torque threshold and the critical value of the speed difference between the two ends of the clutch are set.

[0036] Specifically, based on the driver's accelerator and brake pedal positions, the vehicle's overall controller calculates the threshold value of the motor torque and the critical value of the speed difference between the two ends of the clutch corresponding to the KP point. When the vehicle enters a stable load driving condition, the vehicle's transmission control unit controls the motor torque at this threshold value, stabilizes the motor speed, maintains the engine idle speed, and ensures that the motor speed is higher than the engine speed.

[0037] The reason for setting a threshold for motor torque is that when the clutch reaches the KP point, the clutch begins to transmit torque, the load increases, and the motor output torque will fluctuate significantly. Based on the characteristics of wet clutches, a torque fluctuation value can be set, and the fluctuation value is added to the current torque value as the motor torque threshold. Then, the threshold is used to confirm the critical value of the speed difference between the two ends of the clutch.

[0038] In step S4, the clutch oil chamber is continuously filled with oil.

[0039] Specifically, oil is supplied to the hydraulic control system connected to the clutch pressure plate, and the oil pressure in the hydraulic control system is gradually increased. Under the action of oil pressure, the piston gradually overcomes the elastic force of the return spring and moves closer to the friction plate. When the friction plate just contacts the steel plate, the motor torque and the speed difference between the two ends of the clutch will fluctuate.

[0040] In step S5, the motor torque value and the speed difference between the two ends of the clutch are monitored, and the speed difference and clutch oil pressure are periodically sampled. When the speed difference reaches the critical value, the average value of the clutch oil pressure of the previous five sampling cycles is read and calculated.

[0041] Specifically, during vehicle operation, the speed difference between the two ends of the clutch is continuously collected and processed, while the motor torque value and clutch oil filling pressure value are recorded.

[0042] When the monitored speed difference reaches a preset critical value, the corresponding oil pressure is the KP point corresponding to the control pressure. However, the oil pressure at this moment is affected by sensor reading errors, so it is not used as the KP point obtained through self-learning. Instead, the average oil pressure within the previous five sampling periods is calculated and processed as the KP point oil pressure value for self-learning. The specific sampling process is as follows: Figure 6 As shown.

[0043] The following is a further explanation with reference to an embodiment, and the specific steps are as follows:

[0044] 1. Query adjustment records

[0045] The system checks the clutch KP point hydraulic pressure adjustment record via the transmission control unit. If an adjustment record exists, the KP point hydraulic pressure does not need to be adjusted again during this trip. If no adjustment record exists, the vehicle status is checked.

[0046] 2. Vehicle condition check

[0047] Vehicle data can be queried through the vehicle control unit. This data includes mileage, engine and motor speeds, battery SOC (State of Charge) value, and clutch fluid temperature. Specific standards are: mileage greater than 10,000 kilometers, engine speed between 500-3500 rpm, motor speed between 500-5000 rpm, battery SOC value greater than 70%, and clutch fluid temperature between 80-110℃.

[0048] When the vehicle data meets all the above requirements, the clutch is disengaged via the clutch hydraulic control system. If all the above requirements cannot be met, the clutch KP point hydraulic pressure is not adjusted.

[0049] 3. Adjust the operating conditions of the motor and engine.

[0050] Based on the driver's current accelerator and brake pedal positions, the vehicle control unit determines the threshold value of the motor torque and the critical value of the speed difference between the two ends of the clutch corresponding to the KP point. Then, through the motor control unit and the engine control unit, the motor torque is controlled at this threshold to maintain a constant motor speed, and the engine is then adjusted to idle speed. The transmission control unit immediately monitors and records the speed difference between the two ends of the clutch, the motor torque, and the clutch oil pressure.

[0051] 4. Determine the oil pressure at point KP.

[0052] The transmission control unit retrieves data on the motor speed difference and clutch oil pressure to determine the time point when the motor speed difference reaches the critical value. Then, it reads and calculates the average value of the clutch oil pressure for the previous five sampling cycles at this moment, and the clutch hydraulic control system adjusts the oil pressure at point KP to this average value.

[0053] In summary, the self-learning method for the KP point oil pressure of the K0 clutch in a hybrid vehicle according to an embodiment of the present invention can adjust the KP point oil pressure of the clutch even when the vehicle is in high-speed motion, which changes the limitation of the existing self-learning method that can only be performed under static conditions. Furthermore, by introducing the speed difference as an additional indicator, the obtained KP point oil pressure of the clutch is more accurate.

[0054] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0055] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A self-learning method for the hydraulic pressure at point KP of the K0 clutch in a hybrid vehicle, characterized in that, include: S1. Check the vehicle's status and determine whether the vehicle meets the self-learning conditions of KP point. S2. Adjust the clutch to the disengaged state; S3. Maintain motor torque control mode, constant motor speed, engine idle speed, set motor torque threshold and critical value of speed difference between the two ends of the clutch; S4. Continuously fill the clutch oil chamber with oil; S5. Monitor the motor torque value and the speed difference between the two ends of the clutch. Periodically sample the speed difference and clutch oil pressure. When the speed difference reaches the critical value, read and calculate the average value of the clutch oil pressure of the previous five sampling cycles at this moment. Step S1 includes: Check the vehicle's mileage records to determine if the vehicle's mileage meets the standard. Confirm that the driving load is stable; Check the battery level and determine if the battery SOC value is greater than 70%. Check if the temperature of the lubricating oil in the clutch is normal; Step S5 includes: During vehicle operation, the speed difference between the two ends of the clutch is continuously collected and processed, and the motor torque value and clutch oil filling pressure value are recorded at the same time. Once the speed difference reaches the critical value, the average value of the clutch oil pressure in the previous five sampling cycles is read and calculated as the oil pressure value at point KP.

2. The self-learning method for the hydraulic pressure at point KP of the K0 clutch in a hybrid vehicle according to claim 1, characterized in that, Step S0 is included before step S1, and step S0 includes: Check if the vehicle has a record of adjusting the oil pressure at the KP point; If there are records, self-learning is not required; If there is no record, check the vehicle's status to determine if the vehicle meets the KP point self-learning conditions.

3. The self-learning method for the hydraulic pressure at point KP of the K0 clutch in a hybrid vehicle according to claim 1, characterized in that, Step S2 includes: The clutch status is checked. If the clutch is not disengaged, the oil pressure of the hydraulic control system connected to the clutch pressure plate is adjusted to 0, so that the clutch does not transmit torque between the engine and the motor, thus putting the clutch in the disengaged state.

4. The self-learning method for the hydraulic pressure at point KP of the K0 clutch in a hybrid vehicle according to claim 1, characterized in that, Step S3 includes: The vehicle controller determines the current motor torque based on the driver's accelerator and brake pedal positions; Maintain the motor torque control mode, keep the motor speed constant, and keep the engine idling; Set the motor torque threshold, and determine the critical value of the speed difference between the two ends of the clutch corresponding to point KP based on the threshold.

5. The self-learning method for the hydraulic pressure at point KP of the K0 clutch in a hybrid vehicle according to claim 1, characterized in that, Step S4 includes: Hydraulic oil is supplied to the oil chamber to continuously increase the oil pressure. Under the action of oil pressure, the piston gradually overcomes the elastic force of the return spring and moves closer to the friction plate. At the same time, the speed sensor continuously monitors the speed difference between the engine and motor at both ends of the clutch, and collects and records the oil pressure value and motor torque value during the process.

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