Shift method, shift device and hybrid vehicle

Abstract

The embodiment of the application discloses a gear shifting method, a gear shifting device and a hybrid vehicle, and belongs to the technical field of transmission clutches. The gear shifting method comprises the following steps: in the case that target gear information sent by a vehicle control unit HCU is received, controlling oil filling pressure of a transmission clutch according to a transmission input shaft target torque, and performing gear shifting; in the case that a first clutch temperature estimation value is greater than a first overheating threshold value, controlling the oil filling pressure according to a transmission input shaft limiting torque, and performing gear shifting; in the case that a second clutch temperature estimation value is greater than a second overheating threshold value, sending overheating early warning information to the vehicle control unit HCU; receiving updated target gear information returned by the vehicle control unit HCU, controlling the oil filling pressure according to an updated transmission input shaft target torque, and performing gear shifting from a current gear to the updated target gear. The method can protect the transmission clutch from being ablated and ensure uninterrupted power at the same time.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of transmission clutches, and in particular to a gear shifting method, a gear shifting device, and a hybrid vehicle. Background Art

[0002] To prevent damage to the clutch hardware during gear shifting, existing transmission clutch overheat protection methods typically limit the transmission input shaft's torque when the clutch overheats. This reduces the heat generated by clutch slippage during gear shifting. If torque limiting still fails to prevent clutch heating, pressure relief is triggered to open the clutch and prevent burns.

[0003] When the pressure relief is triggered to open the clutch, the transmission is in neutral, which will cause no power response, jerking and other phenomena during driving, seriously affecting the driving experience. Summary of the Invention

[0004] The present application example provides a shifting method, a shifting device and a hybrid vehicle, and the technical solution is as follows.

[0005] In one aspect, an embodiment of the present application provides a shifting method, which is applied to a transmission control unit (TCU) in a hybrid electric vehicle. The method includes:

[0006] Upon receiving the target gear information sent by the vehicle control unit (HCU), the oil filling pressure of the transmission clutch is controlled according to the target torque of the transmission input shaft, and the gear shift from the current gear to the target gear is executed;

[0007] controlling the charge pressure according to a transmission input shaft limit torque to execute a shift from the current gear to the target gear when a first clutch temperature estimate value is greater than a first overheat threshold, the transmission input shaft limit torque being less than the transmission input shaft target torque, the first clutch temperature estimate value being an estimate of a clutch temperature of the transmission clutch during the shift;

[0008] sending an overheat warning message to the vehicle control unit (HCU) when a second clutch temperature estimate is greater than a second overheat threshold, wherein the second clutch temperature estimate is an estimate of the clutch temperature of the transmission clutch after the gear shift is completed;

[0009] Receive the updated target gear information returned by the vehicle control unit HCU, control the oil filling pressure according to the updated transmission input shaft target torque, and execute a gear shift from the current gear to the updated target gear.

[0010] On the other hand, an embodiment of the present application provides a shifting device, comprising:

[0011] The first shift module is configured to control the oil filling pressure of the transmission clutch according to the target torque of the transmission input shaft and execute the shift from the current gear to the target gear when receiving the target gear information sent by the vehicle control unit HCU;

[0012] a second shift module configured to control the charge pressure according to a transmission input shaft limit torque to execute a shift from the current gear to the target gear when a first clutch temperature estimate is greater than a first overheat threshold, the transmission input shaft limit torque being less than the transmission input shaft target torque, and the first clutch temperature estimate being an estimate of a clutch temperature of the transmission clutch during the shift;

[0013] an overheat warning module, configured to send an overheat warning message to the vehicle control unit (HCU) when a second clutch temperature estimate value is greater than a second overheat threshold value, wherein the second clutch temperature estimate value is an estimate of the clutch temperature of the transmission clutch after the gear shift is completed;

[0014] The first shift module is used to receive the updated target gear information returned by the vehicle control unit HCU, control the oil filling pressure according to the updated transmission input shaft target torque, and execute the shift from the current gear to the updated target gear.

[0015] On the other hand, an embodiment of the present application provides a hybrid vehicle, which is used to implement the shifting method as described in the above aspects.

[0016] In an embodiment of the present application, when the first clutch temperature estimate is greater than the first overheating threshold, the filling oil pressure is controlled according to the transmission input shaft limiting torque, and the shift from the current gear to the target gear is executed. Since the transmission input shaft limiting torque is less than the transmission input shaft target torque, the heat generated by transmission clutch slippage can be reduced, and the transmission clutch can be avoided from burning. When the second clutch temperature estimate is greater than the second overheating threshold, it means that the torque limit cannot guarantee that the transmission clutch will not burn after the shift is completed. Therefore, an overheating warning message is sent to the vehicle control unit HCU so that the vehicle control unit HCU matches the new target gear information. The transmission control unit TCU controls the filling oil pressure according to the updated transmission input shaft target torque, and executes the shift from the current gear to the updated target gear, thereby protecting the transmission clutch from burning while ensuring uninterrupted power and improving the driving experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0018] Figure 1 is a schematic diagram of a hybrid architecture provided by an exemplary embodiment of the present application;

[0019] Figure 2 This is a schematic diagram of a combined gear position of 21 provided by an exemplary embodiment of the present application;

[0020] Figure 3 This is a schematic diagram of a combined gear position of 33 provided by an exemplary embodiment of the present application;

[0021] Figure 4 is a flowchart of a shifting method provided by an exemplary embodiment of the present application;

[0022] Figure 5 is a flow chart of a shifting method provided by another exemplary embodiment of the present application;

[0023] Figure 6 This is a schematic diagram of the change of the transmission input shaft torque at different inertia phase times in the case of upshifting provided by an exemplary embodiment of the present application;

[0024] Figure 7 This is a schematic diagram of the change of the transmission input shaft torque at different inertia phase times in the case of downshifting provided by an exemplary embodiment of the present application;

[0025] Figure 8 is a structural block diagram of a shifting device provided by an exemplary embodiment of the present application;

[0026] Figure 9 This is a diagram of the network communication architecture of a hybrid vehicle provided by an exemplary embodiment of the present application. DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and advantages of this application clearer, the implementation methods of this application will be further described in detail below with reference to the accompanying drawings.

[0028] First, a brief introduction to the terms involved in the embodiments of this application is given:

[0029] Transmission: also known as gearbox, a speed-changing device used to coordinate the speed of the power source and the actual driving speed of the wheels.

[0030] Transmission clutch: a device included in the shift actuator, which is a component for transmitting motion and power.

[0031] Synchronizer: a device included in the shift actuator, which plays a role in smoothly engaging gears when shifting gears. When the transmission is performing a gear shift operation, especially from a high gear to a low gear, it is easy to cause impact between the teeth or spline teeth. The synchronizer can avoid the impact between the teeth.

[0032] Transmission input shaft: used to transmit power generated by the power source to the transmission, and connected to the transmission clutch to enable the transmission to perform a gear shift process.

[0033] Transmission output shaft: used to transmit power to the drive wheels.

[0034] Hybrid vehicle: also known as hybrid power vehicle, driven by two sets of power sources, one of which includes an engine and the other includes a motor.

[0035] In the gear shift process, clutch slip is the main factor causing the temperature of the transmission clutch to rise. The greater the speed ratio difference between the current gear and the target gear, the greater the speed difference between the driving disc and the driven disc of the clutch. In the same gear shift time, the heat generated by the clutch slip in the speed synchronization stage is more. Or the friction coefficient of the clutch decreases after long-term use, causing the torque capacity of the clutch to decrease under the same oil pressure, which easily causes the clutch driving end and the driven end to continuously slip and fail to effectively transmit the torque transmitted by the transmission input shaft, while generating a large amount of heat. When the heat generated by the clutch is higher than the heat capacity threshold, the clutch will have a risk of ablation.

[0036] In the related art, to avoid damage to the clutch hardware, the transmission input shaft is limited in torque when the clutch is overheated to reduce the slip power of the clutch in the gear shift process. When the clutch is still overheated after limiting the torque, the clutch is opened by triggering pressure relief to avoid ablation. Although this over-temperature protection method can avoid ablation of the clutch, when the clutch continues to overheat after limiting the torque, the clutch is opened by triggering pressure relief, so that the transmission is in neutral, which causes no power response and jerk in the driving process, seriously affecting the driving experience.

[0037] Therefore, the present application proposes a gear shift method which can protect the clutch from ablation while ensuring uninterrupted power and avoiding no power response and jerk, thereby improving the driving experience.

[0038] In some embodiments, the gear shift method provided by the embodiments of the present application is applied to a hybrid electric vehicle, and the hybrid architecture of the hybrid electric vehicle is introduced below.

[0039] Referring to Figure 1 , Figure 1 It is a schematic diagram of a hybrid architecture provided by an exemplary embodiment of the present application.

[0040] like Figure 1 The hybrid architecture includes a first power source and a second power source.

[0041] The first power source includes an engine 1 and a first motor 2. The engine 1 and the first motor 2 are coupled and decoupled via a clutch 3. When the clutch 3 is engaged, the output torque of the first power source is the coupled torque between the engine 1 and the first motor 2. When the clutch 3 is disengaged, the output torque of the first power source is equal to the output torque of the first motor 2. The first motor 2 is connected to the outer hubs of the first transmission clutch 5 and the second transmission clutch 6 via a first transmission input shaft 4. The first transmission clutch 5 and the second transmission clutch 6 share a common outer hub.

[0042] The second power source is the second motor 7 , which transmits its power to the second transmission input shaft 9 through the second motor transmission gear set 8 .

[0043] Figure 1 The transmission includes gear sets that realize three speed ratios, namely, the first gear gear set 10, the second gear gear set 11 and the third gear gear set 12.

[0044] Each gear set includes a driving gear and a driven gear. The driving gears of the I-speed gear set 10 and the III-speed gear set 12 are fixed to the second transmission input shaft 9. A first speed sensor 13 is associated with the driving gear of the I-speed gear set 10, and is used to obtain the speed of the second transmission input shaft 9. The driven end of the first transmission clutch 5 is connected to the second transmission input shaft 9. Therefore, the speed of the second transmission input shaft is equal to the speed of the driven end of the first transmission clutch 5. A second speed sensor 14 is associated with the driving gear of the II-speed gear set 11, and is used to obtain the speed of the driving gear of the II-speed gear set 11. The driving gear of the II-speed gear set 11 is connected to the driven end of the second transmission clutch 6. Therefore, the speed of the driving gear of the II-speed gear set 11 is equal to the speed of the driven end of the second transmission clutch 6.

[0045] The transmission also includes a synchronizer 15 , which can achieve power transmission in gear I or gear III depending on the position of the synchronizer 15 . The transmission ultimately outputs power through a transmission output shaft 16 .

[0046] The transmission in this embodiment is a hybrid transmission, which is used to achieve a combination gear, represented by AB, where A is the gear of the first power source and B is the gear of the second power source.

[0047] For example, A=0, I, II, III; B=0, I, II, III.

[0048] According to the different combinations of clutch and synchronizer, different gear combinations can be achieved without interference.

[0049] See also Figure 2 , Figure 2 This is a schematic diagram of a combination gear position of 21 provided by an exemplary embodiment of the present application.

[0050] like Figure 2 As shown, when the combined gear position is 21, the first transmission clutch 5 is disengaged, the second transmission clutch 6 is engaged, and the synchronizer 15 is engaged with the first gear gear set 10. The first motor 2 transmits power through the first transmission input shaft 4, the second transmission clutch 6, and the second gear gear set 11, while the second motor 7 transmits power through the first gear gear set 10.

[0051] See also Figure 3 , Figure 3 This is a schematic diagram of a combined gear position of 33 provided by an exemplary embodiment of the present application.

[0052] like Figure 3 As shown, in the combined gear position of 33, the first transmission clutch 5 is engaged, the second transmission clutch 6 is disengaged, and the synchronizer 15 engages the third gear set 12. The first motor 2 transmits power through the first transmission input shaft 4, the first transmission clutch 5, and the third gear set 12. The second motor 7 also transmits power through the third gear set 12.

[0053] It should be noted that the above description only takes the combination of gears 21 and 33 as an example, and more gear combination modes are not listed here one by one.

[0054] It should be noted that Figure 1 The hybrid architecture shown is for illustrative purposes only. The shifting method proposed in this application is not limited to this architecture and is equally applicable to other multi-speed transmissions that utilize clutch shifting. Alternatively, this architecture may include more or fewer components, or combinations of certain components, which are not limited in this embodiment.

[0055] In some embodiments, the shifting method provided by the present application is applied to the following Figure 1 The hybrid vehicle of the hybrid architecture shown in FIG. includes a first power source and a second power source, the first power source including a first motor, the second power source including a second motor, and the motor that performs the gear shift is the motor corresponding to the power source associated with the target gear in the target gear information.

[0056] For example, the current gear is 23 (the first power source corresponds to 2, and the second power source corresponds to 3), the target gear is 33 (the first power source corresponds to 3, and the second power source corresponds to 3), and the motor performing gear shifting is the first motor included in the first power source, and the second motor corresponding to the second power source does not perform gear shifting.

[0057] The gear shifting method provided in the present application involves multiple gear shifting modes. In each gear shifting mode, the gear shifting process of the clutch is the most serious heat generation, for example, the gear shifting involving the first transmission clutch and the second transmission clutch (such as switching from 23 to 33), or the gear shifting of only one transmission clutch (such as switching from 03 to 23). Therefore, the temperature of the clutch needs to be monitored to prevent overheating and ablation.

[0058] Referring to Figure 4 , Figure 4 is a flowchart of the gear shifting method provided in an exemplary embodiment of the present application. In some embodiments, the method is applied to a transmission control unit (TCU) in a hybrid vehicle. The method includes the following steps.

[0059] In step 401, in the case of receiving the target gear information sent by the vehicle control unit HCU, the oil pressure of the transmission clutch is controlled according to the target torque of the transmission input shaft, and the gear shifting from the current gear to the target gear is performed.

[0060] Optionally, the target gear information includes the target gear to be switched, the target torque of the transmission input shaft required to achieve the target gear, the target gear ratio, and the like. Among them, the target torque of the transmission input shaft is the torque request value sent by the vehicle control unit HCU according to the driver's intention and vehicle running information.

[0061] In some embodiments, the vehicle control unit (HCU) is used to determine the target gear information according to the driver's intention and vehicle running information. For example, the target gear information is determined according to the current driving mode, the current vehicle speed, the accelerator pedal opening degree, and the like.

[0062] In the case of receiving the target gear information sent by the vehicle control unit HCU, the transmission control unit TCU controls the transmission input shaft to perform gear shifting with the target torque in the target gear information.

[0063] For example, the target torque is 200 N·m, and the transmission control unit TCU controls the transmission input shaft torque to be 200 N·m to perform gear shifting.

[0064] At step 402, in a case where the first clutch temperature estimation value is greater than the first overheating threshold value, the oil filling pressure is controlled according to a transmission input shaft limiting torque, the shift from the current gear to the target gear is performed, the transmission input shaft limiting torque is less than the transmission input shaft target torque, and the first clutch temperature estimation value is an estimation value of the clutch temperature of the transmission clutch during the shift.

[0065] During the shift, the transmission control unit TCU can estimate the clutch temperature of the transmission clutch to obtain the first clutch temperature estimation value.

[0066] In a possible implementation, the transmission control unit TCU can determine a plurality of sampling time points in advance, and perform temperature estimation at each sampling time point to obtain the first clutch temperature estimation value of the transmission clutch at each sampling time point.

[0067] During the shift, the heat generated by the transmission clutch slip causes the temperature to rise, and the oil cooling of the transmission clutch causes the temperature to drop, so the estimation of the clutch temperature can be based on the heat generated by the slip and the heat dissipated by the oil cooling. For more information about estimating the clutch temperature, see the following embodiments and their related descriptions, which are not repeated here.

[0068] The first overheating threshold value is a threshold value set for the clutch temperature of the transmission clutch during the shift. Optionally, the first overheating threshold value is 200℃.

[0069] In a case where the first clutch temperature estimation value is greater than the first overheating threshold value, it indicates that there is a risk of ablation of the transmission clutch during the shift, and therefore, in order to avoid ablation of the transmission clutch, the transmission input shaft is limited in torque, and the transmission control unit TCU controls the oil filling pressure according to the transmission input shaft limiting torque to perform the shift, wherein the transmission input shaft limiting torque is less than the transmission input shaft target torque, and for example, the transmission input shaft target torque is 200 N·m, and the transmission input shaft limiting torque is 100 N·m.

[0070] Due to the reduction of the transmission input shaft torque, the heat generated by the transmission clutch slip is reduced, and therefore, the risk of ablation of the transmission clutch is reduced.

[0071] In a possible implementation, the transmission control unit TCU can determine the maximum allowable torque of the transmission input shaft according to the maximum allowable torque corresponding to the clutch temperature, and then send the maximum allowable torque to the vehicle control unit HCU, and the HCU sends the maximum allowable torque to the target power source controller, and then limits the power source output torque, so as to limit the transmission input shaft torque, so as to reduce the heat generated by the transmission clutch slip during the shift.

[0072] Step 403 : When the second clutch temperature estimate value is greater than the second overheat threshold, an overheat warning message is sent to the vehicle control unit HCU. The second clutch temperature estimate value is an estimate of the clutch temperature of the transmission clutch after the gear shift is completed.

[0073] During the gear shifting process, the transmission control unit TCU may estimate the clutch temperature of the transmission clutch at the end of the gear shifting to obtain a second clutch temperature estimation value.

[0074] In one possible implementation, the transmission control unit (TCU) can predetermine the shift time required for the shift and determine the shift end time based on the shift start time. In some embodiments, the TCU estimates the clutch temperature at the start time of torque limiting and determines a second clutch temperature estimate at the shift end time based on the heat generated by clutch slippage during the period between the torque limiting start time and the shift end time, as well as the heat dissipated by oil cooling the clutch.

[0075] The second overheat threshold is a threshold set for the clutch temperature of the transmission clutch at the end of a gear shift. In some embodiments, the second overheat threshold is greater than the first overheat threshold. Optionally, the second overheat threshold is 230°C.

[0076] When the estimated temperature of the second clutch is greater than the second overheating threshold, it means that even by limiting the torque of the transmission input shaft, it is impossible to ensure that the transmission clutch will not burn out after the gear shift is completed. Therefore, the transmission control unit TCU sends an overheating warning message to the vehicle control unit HCU to prompt the vehicle control unit HCU to re-match the target gear.

[0077] Optionally, the overheat warning information may include an estimated value of the second clutch temperature.

[0078] In some embodiments, the vehicle control unit HCU re-matches the target gear based on the received overheat warning information, and re-sends the updated target gear information to the transmission control unit TCU.

[0079] Optionally, the updated target gear information includes the updated target gear, and the updated transmission input shaft target torque and target gear ratio.

[0080] In one possible implementation, the HCU reselects the target gear based on the current driving mode, vehicle speed, and accelerator pedal opening. In another possible implementation, the HCU may also determine the updated target gear based on an estimated temperature of the second clutch.

[0081] Step 404, receiving the updated target gear information returned by the whole vehicle control unit HCU, and controlling the transmission input shaft to perform gear shifting based on the updated target torque.

[0082] In some embodiments, the transmission control unit TCU performs gear shifting based on the updated target torque, for example, the target gear before updating is 33 gear, and the target gear after updating is 23 gear.

[0083] In some embodiments, after controlling the transmission input shaft to perform gear shifting based on the updated target torque, the transmission control unit TCU can also continue to estimate the clutch temperature during gear shifting to obtain a new first clutch temperature estimation value, so as to further determine whether the updated target torque needs to be limited; or the transmission control unit TCU can also continue to estimate the clutch temperature at the end of gear shifting to obtain a second clutch temperature estimation value, so as to further determine whether the target gear needs to be re-matched again.

[0084] In summary, when the first clutch temperature estimation value is greater than the first overheating threshold, the oil filling pressure is controlled according to the transmission input shaft torque limitation, and the gear shifting from the current gear to the target gear is performed. Since the transmission input shaft torque limitation is less than the transmission input shaft target torque, the heat generated by the transmission clutch slip can be reduced, and the transmission clutch ablation can be avoided. When the second clutch temperature estimation value is greater than the second overheating threshold, it means that the transmission clutch ablation cannot be prevented after gear shifting is completed by limiting torque. Therefore, an overheating warning information is sent to the whole vehicle control unit HCU, so that the whole vehicle control unit HCU matches new target gear information. The transmission control unit TCU controls the oil filling pressure according to the updated transmission input shaft target torque, and performs gear shifting from the current gear to the updated target gear. Thus, the transmission clutch is protected from ablation while the power is not interrupted, and the driving experience is improved.

[0085] Referring to Figure 5 , Figure 5 is a flowchart of a gear shifting method provided by another exemplary embodiment of the present application. The method comprises the following steps.

[0086] Step 510, the whole vehicle control unit HCU sends target gear information to the transmission control unit TCU.

[0087] For example, the current gear is 03 gear, and the whole vehicle control unit HCU determines that the target gear is 23 gear according to the driver's intention and vehicle running information, and the request value of the transmission input shaft torque is the target torque 200 N·m.

[0088] In step 520 , the transmission control unit TCU controls the oil filling pressure of the transmission clutch according to the transmission input shaft target torque, performs gear shifting, and calculates a first clutch temperature estimation value corresponding to the current sampling moment.

[0089] Exemplarily, the previous sampling time is the 20th ms, the current sampling time is the 30th ms, and the sampling duration is 10 ms.

[0090] In some embodiments, the estimated temperature value of the first clutch corresponding to the current sampling moment can be calculated by sliding friction work and heat dissipation work.

[0091] In some embodiments, the transmission control unit TCU determines a first slipping work corresponding to a current sampling moment, where the first slipping work is heat generated by slipping of the transmission clutch during the sampling period.

[0092] Regarding the method of determining the first slip work, in some embodiments, the transmission control unit TCU determines the first slip work corresponding to the current sampling moment based on the clutch transmission torque, clutch slip (unit: rpm), slip coefficient and sampling time (unit: ms).

[0093] Optionally, the first sliding friction work is calculated using the following formula.

[0094] The first slip work = clutch transmission torque × (clutch slip × π / 30) × slip coefficient × (sampling time / 1000).

[0095] Among them, the clutch transmission torque is the torque applied by the power source to the passive end of the transmission clutch through the clutch friction plate, and the clutch slip is the speed difference between the active end and the driven end of the transmission clutch.

[0096] Regarding clutch torque transmission, it can include any of the following methods:

[0097] (1) When the clutch slip is less than or equal to the clutch slip threshold and the torque of the transmission input shaft is less than the clutch torque capacity, the torque applied by the power source to the active end of the transmission clutch is determined as the clutch transfer torque.

[0098] Optionally, the clutch slip threshold is a threshold preset by the transmission control unit TCU, such as 30 rpm.

[0099] Optionally, the clutch torque capacity is calculated based on the current clutch fluid pressure.

[0100] When the clutch slip is less than or equal to the preset clutch slip threshold, that is, the speed difference is relatively small, the speed of the clutch active end and the driven end are close to synchronization, and when the torque of the transmission input shaft is less than the clutch torque capacity, the transmission clutch can transmit all the torque output by the power source. Therefore, the torque transmitted from the power source to the clutch active end is taken as the clutch transmission torque, which has higher calculation efficiency.

[0101] (2) When the clutch slip is greater than the clutch slip threshold, the clutch transmission torque is determined based on the friction radius, number of friction plates, friction coefficient, piston cavity inner diameter, piston cavity outer diameter, maximum working state return spring force, and oil pressure controlled by the solenoid valve of the transmission clutch.

[0102] In some embodiments, the transmission control unit TCU determines a first heat dissipation work corresponding to the current sampling moment, where the first heat dissipation work is the heat generated by the oil cooling the transmission clutch during the sampling period.

[0103] Regarding the determination method of the first heat dissipation work, in some embodiments, the transmission control unit TCU is based on the first clutch temperature estimation value corresponding to the previous sampling moment, the oil temperature, the cooling coefficient, the oil flow rate (unit: L / min), the oil density (unit: kg / m ∧ 3) The specific heat capacity of the oil and the sampling time (unit: ms) are used to determine the first heat dissipation work corresponding to the current sampling moment.

[0104] Optionally, the first heat dissipation work is calculated using the following formula.

[0105] First heat dissipation work=(the estimated temperature of the first clutch at the previous sampling moment - the oil temperature)×cooling coefficient×(oil flow rate / 60000)×(sampling time / 1000)×oil density×oil specific heat capacity.

[0106] In some embodiments, the oil temperature can be measured by a temperature sensor. A mapping relationship exists between the oil density and specific heat capacity, and the oil temperature. The transmission control unit (TCU) can pre-determine this mapping relationship through experimental measurements and store it to determine the oil density and specific heat capacity. In some embodiments, the cooling coefficient can be determined based on empirical values ​​and pre-stored in the transmission control unit (TCU).

[0107] In some embodiments, the transmission main oil pressure can be obtained by measurement, and there is a mapping relationship between the oil flow and the transmission main oil pressure. The transmission control unit TCU can obtain the mapping relationship in advance through experimental measurement and store the mapping relationship to determine the oil flow.

[0108] It should be noted that since the sampling time of each signal in the TCU is in milliseconds, it can be assumed that the transmission main oil pressure and oil temperature remain unchanged within the sampling time, that is, the oil flow rate, oil specific heat capacity and oil density remain unchanged.

[0109] After calculating the first sliding friction work and the first heat dissipation work, the transmission control unit TCU determines the first clutch temperature estimation value corresponding to the current sampling moment based on the first sliding friction work, the first heat dissipation work and the first clutch temperature estimation value corresponding to the previous sampling moment.

[0110] The estimated value of the first clutch temperature corresponding to the current sampling moment can be calculated using the following formula.

[0111] The estimated temperature value of the first clutch at the current sampling moment=the estimated temperature value of the first clutch at the previous sampling moment+(first sliding friction work−first heat dissipation work)÷clutch specific heat capacity÷clutch mass.

[0112] Step 530 , determining whether the estimated value of the first clutch temperature is greater than a first overheating threshold.

[0113] Exemplarily, the first overheating threshold is 200° C., or other preset thresholds, which are not limited thereto.

[0114] When the first clutch temperature estimation value is less than or equal to the first overheat threshold, step 541 is executed; when the first clutch temperature estimation value is greater than the first overheat threshold, step 542 is executed.

[0115] Step 541 : Control the oil filling pressure according to the target torque of the transmission input shaft and continue to shift gears.

[0116] Since the first clutch temperature estimation value is less than or equal to the first overheat threshold, the transmission control unit TCU determines that there is no risk of ablation of the transmission clutch, and therefore gear shifting can continue to be performed using the target torque.

[0117] Step 542 : Control the oil filling pressure according to the transmission input shaft torque limit and execute the gear shift.

[0118] The transmission input shaft limit torque is less than the transmission input shaft target torque. For example, the transmission input shaft target torque is 200 N·m, and the transmission input shaft limit torque is 120 N·m.

[0119] In one possible implementation, the transmission control unit TCU sends a torque limit signal to the vehicle controller HCU, which then transmits the torque limit signal to the corresponding power source controller to limit the power source output torque, thereby limiting the transmission input shaft torque.

[0120] Step 550 : Calculate the estimated temperature of the second clutch corresponding to the shift end time.

[0121] The second clutch temperature estimate is an estimate of the clutch temperature of the transmission clutch at the end of the gear shift.

[0122] In some embodiments, the transmission control unit TCU may predetermine the shift time required for the gear shift, and determine the gear shift end time based on the gear shift start time.

[0123] Similar to the first clutch temperature estimation value, in some embodiments, the second clutch temperature estimation value corresponding to the shift end time can be obtained by calculating the sliding friction work and the heat dissipation work.

[0124] In some embodiments, the transmission control unit (TCU) determines the second slippage work generated between the start of the torque limit and the end of the shift based on the transmission input shaft torque limit, clutch slip, and the remaining shift time. For ease of calculation, the following assumptions are made:

[0125] (1) Since the gear shift has been executed for a period of time, the current speed of the transmission input shaft is not much different from the target speed. The influence of the inertia torque caused by the change in the speed of the transmission input shaft is not considered. It is assumed that the transmission input shaft limit torque remains constant during the gear shift after the torque limit.

[0126] (2) The remaining shift time Δt (unit: ms) can be obtained by subtracting the executed shift time from the preset total shift time, where the executed shift time can be calculated by the TCU.

[0127] (3) The clutch slip n2 - n1 changes linearly with the sampling time, where n1 is the transmission input shaft speed at the start of torque limiting, and n2 is the target input shaft speed corresponding to the target gear. n1 can be obtained from the speed sensor, and n2 can be calculated from the TCU. The speed unit is rpm. The slip angle θ after the clutch driving and driven ends synchronize their speeds is 2π × ((n2 - n1) / 60) × ((Δt / 2) / 1000).

[0128] Based on the above assumptions, the second slip work of the clutch from the start of torque limiting to the end of gear shifting can be expressed as:

[0129] W=Tthd×θ=Tthd×π×((n2-n1)×Δt / 60000);

[0130] Among them, Tthd is the transmission input shaft limit torque.

[0131] In some embodiments, the transmission control unit TCU determines the second heat dissipation work generated between the start of torque limiting and the end of the gear shift based on the estimated clutch temperature at the start of torque limiting, the oil temperature, oil flow, oil specific heat capacity, oil density and the remaining gear shift time.

[0132] Optionally, the second heat dissipation work is calculated using the following formula.

[0133] Second heat dissipation work=(estimated first clutch temperature at the start of torque limiting−oil temperature at the start of torque limiting)×cooling coefficient×oil flow rate×remaining shift time×oil density×oil specific heat capacity.

[0134] After determining the second sliding friction work and the second heat dissipation work, the transmission control unit TCU determines the second clutch temperature estimation value corresponding to the shift end time based on the second sliding friction work, the second heat dissipation work and the first clutch temperature estimation value corresponding to the torque limit start time.

[0135] The estimated temperature of the second clutch corresponding to the end of the shift is calculated using the following formula.

[0136] The estimated second clutch temperature corresponding to the end of the shift = the estimated first clutch temperature corresponding to the start of the torque limit + (second sliding friction work - second heat dissipation work) / clutch specific heat capacity / clutch mass.

[0137] Step 560 , determining whether the estimated value of the second clutch temperature is greater than a second overheat threshold.

[0138] In some embodiments, the second overheating threshold is greater than the first overheating threshold. For example, the second overheating threshold is 230° C., or other preset thresholds, which are not limited thereto.

[0139] When the first clutch temperature estimation value is less than or equal to the first overheat threshold, step 571 is executed; when the first clutch temperature estimation value is greater than the first overheat threshold, step 572 is executed.

[0140] Step 571 , controlling the oil filling pressure according to the transmission input shaft limit torque, and continuing the gear shift.

[0141] Since the second clutch temperature estimation value is less than or equal to the second overheating threshold, the transmission control unit TCU determines that there is no risk of ablation of the transmission clutch, and therefore gear shifting can continue to be performed with limited torque.

[0142] Step 572: When the second clutch temperature estimation value is greater than the second overheat threshold, the transmission control unit TCU sends an overheat warning message to the vehicle control unit HCU, so that the vehicle control unit HCU determines the updated target gear information.

[0143] wherein the target gear in the updated target gear information is an adjacent gear to the target gear before the update.

[0144] In the case where the second clutch temperature estimation value is greater than the second overheating threshold, it indicates that the heat generated by switching the current gear to the target gear is too high, and the risk of burnout of the transmission clutch cannot be avoided by limiting the transmission input shaft torque, therefore, the vehicle control unit HCU can re-match a gear adjacent to the target gear before the update, to reduce the heat generated by the transmission clutch slip, thereby avoiding the burnout of the transmission clutch.

[0145] For example, the current gear is 03 gear, the target gear is 23 gear, and in the case where the second clutch temperature estimation value is greater than the second overheating threshold, the vehicle control unit HCU determines that the updated target gear is the gear (33 gear) adjacent to the target gear before the update.

[0146] After determining the updated target gear, the vehicle control unit HCU sends the updated target gear information to the transmission control unit TCU, and the transmission control unit TCU receives the updated target gear information returned by the vehicle control unit HCU, and controls the oil filling pressure to perform gear shifting based on the updated transmission input shaft target torque.

[0147] In this embodiment, in the case where the second clutch temperature estimation value is greater than the second overheating threshold, by re-matching a gear adjacent to the target gear as a new target gear, the original target gear corresponding clutch can be exited in time, and the power is transmitted through the clutch corresponding to the new target gear, which protects the transmission clutch from being burned out while ensuring uninterrupted power and improving the driving experience.

[0148] During the inertia phase of gear shifting, the change in transmission input shaft speed will generate inertia torque, which needs to be controlled to prevent impact. In related technologies, the torque value currently requested by the power source is summed or subtracted from the calculated inertia torque according to the type of gear shifting, as the torque value output by the power source during gear shifting. However, controlling the power source to suddenly increase or decrease a torque equal to the size of the inertia torque will cause the system to impact, affecting the smoothness of gear shifting.

[0149] Therefore, in some embodiments, the present application also introduces a method of smoothing and superimposing inertia torque according to inertia loading process coefficients or inertia unloading process coefficients, to further enhance the smoothness of gear shifting and improve the driving experience.

[0150] Regarding the calculation method of inertia torque, in some embodiments, the transmission control unit TCU determines the target speed of the transmission input shaft based on the transmission output shaft speed and the target gear ratio in the updated target gear information, and determines the current speed of the transmission input shaft based on the transmission output shaft speed and the current gear ratio.

[0151] Target speed = target gear ratio × transmission output shaft speed; current speed = current gear ratio × transmission output shaft speed. The transmission output shaft speed is calculated by multiplying the speed measured by the wheel-end speed sensor by the final drive ratio. All speed ratios in this application (including current gear ratio, target gear ratio, and final drive ratio) are the ratios of the driving gear speed to the driven gear speed.

[0152] After determining the target speed and current speed of the transmission input shaft, the difference between the target speed and the current speed is determined as the speed difference between the driving plate and the driven plate of the transmission clutch, and the inertia torque is determined based on the speed difference, inertia phase time, rotational inertia and inertia coefficient.

[0153] The inertia phase time is the sum of the inertia loading time corresponding to the inertia loading phase, the speed regulation time corresponding to the speed regulation phase, and the inertia unloading time corresponding to the inertia unloading phase.

[0154] Optionally, the inertia torque is calculated using the following formula.

[0155] Inertia torque = speed difference ÷ inertia phase time × moment of inertia × inertia coefficient.

[0156] Optionally, the inertia loading time, the speed regulation time, and the inertia unloading time are all predetermined based on experience and are ultimately determined through repeated experiments on the premise of balancing the total shifting time and the shifting smoothness.

[0157] Optionally, the inertia coefficient is determined based on the current speed and torque of the motor, calibrated and adjusted according to actual test results, and pre-stored in the TCU.

[0158] In some embodiments, the oil filling pressure of the transmission clutch is controlled according to the target torque of the transmission input shaft, and the shift from the current gear to the target gear is executed in the following three stages.

[0159] (1) Inertia loading stage.

[0160] In some embodiments, during the inertia loading phase, the transmission control unit (TCU) controls the charge pressure to perform a gear shift according to an inertia loading torque determined based on the inertia torque, the target torque, and the inertia loading process coefficient.

[0161] Optionally, the inertia loading progress coefficient is the ratio of the executed inertia loading time to the total inertia loading time.

[0162] In a possible scenario, in the case of upshift, the transmission input shaft speed decreases due to the decrease of the transmission ratio, and a positive inertial torque is applied to the wheel end during the process of the decrease of the input shaft speed, thus, the motor output torque needs to be controlled to decrease in order to control the transmission input shaft torque to decrease in the upshift.

[0163] In some embodiments, in the case of upshift, the inertial loading torque is the difference between the transmission input shaft target torque and the product of the inertial torque and the inertial loading process coefficient.

[0164] For example, the transmission input shaft target torque is 200 N·m, the inertial torque is 10 N·m, and the inertial loading process coefficient is 30%, in the case of upshift, the inertial loading torque is 197 N·m.

[0165] In a possible scenario, in the case of downshift, the transmission input shaft speed increases due to the increase of the transmission ratio, and a negative inertial torque is applied to the wheel end during the process of the increase of the input shaft speed, thus, the motor output torque needs to be controlled to increase in order to control the transmission input shaft torque to increase in the downshift.

[0166] In some embodiments, in the case of downshift, the inertial loading torque is the sum of the transmission input shaft target torque and the product of the inertial torque and the inertial loading process coefficient.

[0167] For example, the transmission input shaft target torque is 100 N·m, the inertial torque is 5 N·m, and the inertial loading process coefficient is 80%, in the case of downshift, the inertial loading torque is 104 N·m.

[0168] (2) Speed regulation phase.

[0169] In some embodiments, in the speed regulation phase, the transmission control unit TCU adjusts the motor speed to the target speed, and performs the shift according to the superimposed value of the transmission input shaft target torque and the inertial torque.

[0170] The speed regulation phase mainly completes the speed regulation of the transmission input shaft, so that it reaches the target speed.

[0171] Optionally, the target speed is the transmission output shaft speed multiplied by the target gear ratio.

[0172] In a possible scenario, in the case of upshift, the superimposed value of the transmission input shaft target torque and the inertial torque is the difference between the transmission input shaft target torque and the inertial torque.

[0173] For example, the transmission input shaft target torque is 200 N·m, and the inertial torque is 10 N·m, in the case of upshift, the superimposed value is 190 N·m.

[0174] In one possible scenario, in the case of downshifting, the superposition value of the transmission input shaft target torque and the inertia torque is the sum of the transmission input shaft target torque and the inertia torque.

[0175] For example, the target torque of the transmission input shaft is 100 N·m, the inertia torque is 5 N·m, and in the case of downshifting, the superposition value is 105 N·m.

[0176] (3) Inertial unloading stage.

[0177] In some embodiments, during the inertia unloading phase, the transmission control unit TCU performs shifting according to the inertia unloading torque, which is determined based on the inertia torque, the transmission input shaft target torque, and the inertia unloading process coefficient.

[0178] Optionally, the inertia unloading process coefficient is a ratio of the executed inertia unloading time to the total inertia unloading time.

[0179] In some embodiments, in the case of an upshift, the inertia unloading torque is the sum of the overlay value and the product of the inertia torque and the inertia unloading process coefficient.

[0180] For example, the superposition value is 100 N·m, the inertia torque is 10 N·m, and the inertia unloading process coefficient is 30%, then the inertia unloading torque=100+10×30%=10 3 N·m.

[0181] In some embodiments, in the case of a downshift, the inertia unloading torque is the difference between the overlay value and the product of the inertia torque and the inertia unloading process coefficient.

[0182] For example, the superposition value is 150 N·m, the inertia torque is 5 N·m, and the inertia unloading process coefficient is 80%, then the inertia unloading torque = 150 - 5 × 80% = 146 N·m.

[0183] See also Figure 6 , Figure 6 This is a schematic diagram of the change of the transmission input shaft torque at different inertia phase times in the case of upshifting provided by an exemplary embodiment of the present application.

[0184] like Figure 6 As shown, in the case of upshifting, in the inertia loading stage, the transmission input shaft torque is reduced from the target torque to the target torque-inertia torque according to the inertia loading process coefficient; in the speed regulation stage, the transmission input shaft torque remains at the target torque-inertia torque; in the inertia unloading stage, the transmission input shaft is increased from the target torque-inertia torque to the target torque according to the inertia unloading process coefficient.

[0185] In some embodiments, the sum of the inertia loading time corresponding to the inertia loading phase, the speed regulation time corresponding to the speed regulation phase, and the inertia unloading time corresponding to the inertia unloading phase is the total time of the shift process.

[0186] As to the determination of the inertia loading time and the inertia unloading time, in one possible implementation, the inertia loading time and the inertia unloading time can be determined according to the product of a preset proportion value and the total time of the shift process.

[0187] Optionally, the inertia loading time is usually 5% to 10% of the total time of the shift process from the start time; and the inertia unloading time is usually from the time of 90% to 95% of the total time to the end of the shift process.

[0188] For example, the total time of the shift process is 600 ms, the inertia loading time is the first 10%, and the inertia unloading time is the last 10%. Thus, the inertia loading time is from the first ms to the 60th ms, and the inertia unloading time is from the 541st ms to the 600th ms.

[0189] Referring to Figure 7 , Figure 7 is a schematic diagram of the change of the torque of the input shaft of the transmission in different inertia phases in the case of downshift according to an example embodiment of the present application.

[0190] As shown in Figure 7 , in the case of downshift, in the inertia loading phase, the torque of the input shaft of the transmission is increased from the target torque to the target torque + inertia torque according to the inertia loading process coefficient; in the speed regulation phase, the torque of the input shaft of the transmission is kept at the target torque + inertia torque; and in the inertia unloading phase, the torque of the input shaft of the transmission is decreased from the target torque + inertia torque to the target torque according to the inertia unloading process coefficient.

[0191] In this embodiment, the torque of the input shaft of the transmission is gradually adjusted by the inertia loading process coefficient and the inertia unloading process coefficient, so that the inertia torque is stably output in the inertia phase. Through the control in the three phases of the inertia loading phase, the speed regulation phase, and the inertia unloading phase, the speed regulation of the input shaft of the transmission is completed while the smoothness of the shift process is ensured, and the driving experience is improved.

[0192] Referring to Figure 8 , Figure 8 is a structural block diagram of a shift device according to an example embodiment of the present application.

[0193] The device comprises:

[0194] The first shift module 801 is configured to, in the case of receiving the target gear information sent by the vehicle control unit HCU, control the oil filling pressure of the transmission clutch according to the target torque of the input shaft of the transmission, and perform the shift from the current gear to the target gear.

[0195] a second shift module 802 configured to control the oil charging pressure according to a transmission input shaft limit torque to execute a shift from the current gear to the target gear when a first clutch temperature estimate is greater than a first overheat threshold, the transmission input shaft limit torque being less than the transmission input shaft target torque, and the first clutch temperature estimate being an estimate of a clutch temperature of the transmission clutch during the shift;

[0196] an overheat warning module 803, configured to send an overheat warning message to the vehicle control unit (HCU) when a second clutch temperature estimate value is greater than a second overheat threshold value, wherein the second clutch temperature estimate value is an estimate of the clutch temperature of the transmission clutch after the gear shift is completed;

[0197] The first shift module 801 is used to receive the updated target gear information returned by the vehicle control unit HCU, control the oil filling pressure according to the updated transmission input shaft target torque, and execute the shift from the current gear to the updated target gear.

[0198] Optionally, the first shift module 801 is configured to:

[0199] When the first clutch temperature estimation value is less than or equal to the first overheat threshold, controlling the charge pressure according to the transmission input shaft target torque to continue shifting;

[0200] Optionally, the second shift module 802 is configured to:

[0201] When the second clutch temperature estimation value is greater than the first overheat threshold and less than or equal to the second overheat threshold, the shift is continued by controlling the charge pressure according to the transmission input shaft limit torque.

[0202] Optionally, the overheating warning module 803 is used to:

[0203] When the second clutch temperature estimation value is greater than the second overheating threshold, the overheating warning information is sent to the vehicle control unit HCU, so that the vehicle control unit HCU determines the updated target gear information, wherein the target gear in the updated target gear information is an adjacent gear to the target gear before the update.

[0204] Optionally, the overheating warning module 803 is used to:

[0205] Determining a first sliding friction work corresponding to a current sampling moment, where the first sliding friction work is heat generated by sliding friction of the transmission clutch during a sampling period;

[0206] determine a first heat dissipation work corresponding to the current sampling moment, the first heat dissipation work being heat dissipated by the oil to cool the transmission clutch in the sampling duration;

[0207] determine the first clutch temperature estimation value corresponding to the current sampling moment based on the first sliding friction work, the first heat dissipation work and the first clutch temperature estimation value corresponding to the previous sampling moment.

[0208] Optionally, the overheating warning module 803 is configured to:

[0209] determine the first sliding friction work corresponding to the current sampling moment based on clutch transmission torque, clutch slip, sliding friction coefficient and sampling duration, the clutch transmission torque being torque applied by the power source to the driven end of the transmission clutch through the clutch friction plate, and the clutch slip being the speed difference between the driving end and the driven end of the transmission clutch;

[0210] the determination of the first heat dissipation work corresponding to the current sampling moment comprises:

[0211] determine the first heat dissipation work corresponding to the current sampling moment based on the first clutch temperature estimation value corresponding to the previous sampling moment, oil temperature, cooling coefficient, oil flow, oil density, specific heat capacity of the oil and the sampling duration.

[0212] Optionally, the overheating warning module 803 is configured to:

[0213] determine the clutch transmission torque based on the clutch transmission torque, the clutch slip, the sliding friction coefficient, the friction radius of the transmission clutch, the number of friction plates, the friction coefficient, the inner diameter of the piston cavity, the outer diameter of the piston cavity, the maximum working state return spring force and the oil pressure controlled by the electromagnetic valve in the case where the clutch slip is greater than the clutch slip threshold.

[0214]

[0215] Optionally, the overheating warning module 803 is configured to:

[0216] determine the second sliding friction work generated between the torque limiting start moment and the gear shifting end moment according to the transmission input shaft limiting torque, the clutch slip and the remaining gear shifting duration;

[0217] determine the second heat dissipation work generated between the torque limiting start moment and the gear shifting end moment according to the first clutch temperature estimation value corresponding to the torque limiting start moment, the oil temperature, the oil flow, the specific heat capacity of the oil, the oil density and the remaining gear shifting duration.​

[0218] An estimated temperature value of the second clutch corresponding to the shift end time is determined based on the second sliding friction work and the second heat dissipation work.

[0219] Optionally, the first shift module 801 is configured to:

[0220] During the inertia loading phase, the gear shift is performed by controlling the oil filling pressure according to the inertia loading torque, wherein the inertia loading torque is determined based on the inertia torque, the transmission input shaft target torque, and an inertia loading process coefficient;

[0221] In the speed regulation phase, the motor speed is adjusted to the target speed, and gear shifting is performed according to the superposition value of the transmission input shaft target torque and the inertia torque;

[0222] During the inertia unloading phase, the gear shift is performed by controlling the charge pressure according to an inertia unloading torque determined based on the inertia torque, the transmission input shaft target torque, and an inertia unloading process coefficient.

[0223] Optionally, in the case of an upshift, the superposition value is the difference between the transmission input shaft target torque and the inertia torque, the inertia loading torque is the difference between the transmission input shaft target torque and the product of the inertia torque and the inertia loading process coefficient, and the inertia unloading torque is the sum of the superposition value and the product of the inertia torque and the inertia unloading process coefficient;

[0224] In the case of downshifting, the superposition value is the sum of the transmission input shaft target torque and the inertia torque, the inertia loading torque is the sum of the transmission input shaft target torque and the product of the inertia torque and the inertia loading process coefficient, and the inertia unloading torque is the difference between the superposition value and the product of the inertia torque and the inertia unloading process coefficient.

[0225] See also Figure 9 , Figure 9 This is a diagram of the network communication architecture of a hybrid vehicle provided by an exemplary embodiment of the present application.

[0226] like Figure 9 As shown, the shifting method proposed in this application is implemented based on Controller Area Network (CAN) communication.

[0227] The node controller units on the CAN bus include, but are not limited to, a gearbox control unit TCU, a vehicle control unit HCU, an engine control unit EMS (Engine Management System), and a motor control unit MCU (Motor Control Unit). The signals of each controller are routed through a central gateway CGW (Central Gateway). For example, after the vehicle controller HCU receives a power request, the vehicle controller HCU sends a torque request to the engine management system EMS and the motor control unit MCU. The engine output torque and the motor output torque are coupled, and finally transmitted to the wheels through the transmission to drive the car to travel.

[0228] The scheme shown in the above embodiments of the application can be applied to a hybrid electric vehicle.

[0229] The application further provides a hybrid electric vehicle for implementing the gear shifting method of any one of the above embodiments.

[0230] A person of ordinary skill in the art can understand that all or part of the steps of the above embodiments can be completed by hardware, or by a program instructing relevant hardware, and the program can be stored in a computer readable storage medium. The storage medium mentioned above can be a read-only memory, a magnetic disk or an optical disk.

[0231] The above is only an optional embodiment of the application and is not used to limit the application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the application shall be included in the protection scope of the application.

Claims

1. A shifting method, characterized in that: The method is applied to a transmission control unit (TCU) in a hybrid vehicle, and comprises: Upon receiving the target gear information sent by the vehicle control unit (HCU), the oil filling pressure of the transmission clutch is controlled according to the target torque of the transmission input shaft, and the gear shift from the current gear to the target gear is executed; controlling the charge pressure according to a transmission input shaft limit torque to execute a shift from the current gear to the target gear when a first clutch temperature estimate value is greater than a first overheat threshold, the transmission input shaft limit torque being less than the transmission input shaft target torque, the first clutch temperature estimate value being an estimate of a clutch temperature of the transmission clutch during the shift; sending an overheat warning message to the vehicle control unit (HCU) when a second clutch temperature estimate is greater than a second overheat threshold, wherein the second clutch temperature estimate is an estimate of the clutch temperature of the transmission clutch after the gear shift is completed; Receive the updated target gear information returned by the vehicle control unit HCU, control the oil filling pressure according to the updated transmission input shaft target torque, and execute a gear shift from the current gear to the updated target gear.

2. The method according to claim 1, characterized in that The method further comprises: When the first clutch temperature estimation value is less than or equal to the first overheat threshold, controlling the charge pressure according to the transmission input shaft target torque to continue shifting; When the second clutch temperature estimation value is greater than the first overheat threshold and less than or equal to the second overheat threshold, the shift is continued by controlling the charge pressure according to the transmission input shaft limit torque.

3. The method according to claim 1, characterized in that The step of sending overheat warning information to the vehicle control unit HCU when the estimated temperature value of the second clutch is greater than a second overheat threshold comprises: When the second clutch temperature estimation value is greater than the second overheating threshold, the overheating warning information is sent to the vehicle control unit HCU, so that the vehicle control unit HCU determines the updated target gear information, wherein the target gear in the updated target gear information is an adjacent gear to the target gear before the update.

4. The method according to claim 1, wherein The method further comprises: Determining a first sliding friction work corresponding to a current sampling moment, where the first sliding friction work is heat generated by sliding friction of the transmission clutch during a sampling period; determining a first heat dissipation work corresponding to the current sampling moment, where the first heat dissipation work is the amount of heat generated by the oil cooling the transmission clutch during the sampling period; The first clutch temperature estimation value corresponding to the current sampling moment is determined based on the first sliding friction work, the first heat dissipation work, and the first clutch temperature estimation value corresponding to the previous sampling moment.

5. The method according to claim 4, characterized in that Determining the first sliding friction work corresponding to the current sampling moment includes: determining the first slipping work corresponding to the current sampling moment based on the clutch transmission torque, clutch slip, slip coefficient, and sampling duration, wherein the clutch transmission torque is the torque applied by the power source to the passive end of the transmission clutch through the clutch friction plate, and the clutch slip is the speed difference between the active end and the driven end of the transmission clutch; The determining the first heat dissipation work corresponding to the current sampling moment includes: The first heat dissipation work corresponding to the current sampling moment is determined based on the first clutch temperature estimation value, oil temperature, cooling coefficient, oil flow, oil density, oil specific heat capacity, and the sampling duration corresponding to the previous sampling moment.

6. The method according to claim 1, characterized in that The method further comprises: determining a second sliding friction work generated between the start time of torque limiting and the end time of gear shifting according to the transmission input shaft limit torque, clutch slip, and remaining gear shifting time; determining a second heat dissipation work generated between the start time of torque limiting and the end time of the gear shift based on the estimated temperature of the first clutch corresponding to the start time of torque limiting, the oil temperature, oil flow rate, oil specific heat capacity, oil density, and the remaining gear shift time at the start time of torque limiting; An estimated temperature value of the second clutch corresponding to the shift end time is determined based on the second sliding friction work and the second heat dissipation work.

7. The method according to claim 1, characterized in that The step of controlling the oil filling pressure of the transmission clutch according to the target torque of the transmission input shaft to execute the shift from the current gear to the target gear includes: During the inertia loading phase, the gear shift is performed by controlling the oil filling pressure according to the inertia loading torque, wherein the inertia loading torque is determined based on the inertia torque, the transmission input shaft target torque, and an inertia loading process coefficient; In the speed regulation phase, the motor speed is adjusted to the target speed, and gear shifting is performed according to the superposition value of the transmission input shaft target torque and the inertia torque; During the inertia unloading phase, the gear shift is performed by controlling the charge pressure according to an inertia unloading torque determined based on the inertia torque, the transmission input shaft target torque, and an inertia unloading process coefficient.

8. The method according to claim 7, characterized in that In the case of an upshift, the superposition value is the difference between the transmission input shaft target torque and the inertia torque, the inertia loading torque is the difference between the transmission input shaft target torque and the product of the inertia torque and the inertia loading process coefficient, and the inertia unloading torque is the sum of the superposition value and the product of the inertia torque and the inertia unloading process coefficient; In the case of downshifting, the superposition value is the sum of the transmission input shaft target torque and the inertia torque, the inertia loading torque is the sum of the transmission input shaft target torque and the product of the inertia torque and the inertia loading process coefficient, and the inertia unloading torque is the difference between the superposition value and the product of the inertia torque and the inertia unloading process coefficient.

9. A gear shifting device, characterized in that: The device comprises: The first shift module is configured to control the oil filling pressure of the transmission clutch according to the target torque of the transmission input shaft and execute the shift from the current gear to the target gear when receiving the target gear information sent by the vehicle control unit HCU; a second shift module configured to control the charge pressure according to a transmission input shaft limit torque to execute a shift from the current gear to the target gear when a first clutch temperature estimate is greater than a first overheat threshold, the transmission input shaft limit torque being less than the transmission input shaft target torque, and the first clutch temperature estimate being an estimate of a clutch temperature of the transmission clutch during the shift; an overheat warning module, configured to send an overheat warning message to the vehicle control unit (HCU) when a second clutch temperature estimate value is greater than a second overheat threshold value, wherein the second clutch temperature estimate value is an estimate of the clutch temperature of the transmission clutch after the gear shift is completed; The first shift module is used to receive the updated target gear information returned by the vehicle control unit HCU, control the oil filling pressure according to the updated transmission input shaft target torque, and execute the shift from the current gear to the updated target gear.

10. A hybrid vehicle, characterized in that: The hybrid electric vehicle includes a transmission control unit TCU, a vehicle control unit HCU, an engine control unit EMS and a motor control unit MCU. The transmission control unit TCU is used to implement the shifting method according to any one of claims 1 to 8.

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