Gear shifting control method and gear shifting control device for vehicle power system

Abstract

The invention provides a gear shifting control method for a vehicle power system. In the rotating speed synchronization step of the gear shifting control method, the expected rotating speed difference and the rotating speed reference value are calculated through the parameters of the vehicle, and whether the rotating speed synchronization step is executed smoothly or not is judged according to the size relation between the absolute value of the expected rotating speed difference and the absolute value of the rotating speed reference value. According to the gear shifting control method in the prior art, whether the rotating speed synchronization step is executed smoothly or not is judged through the time threshold value in the rotating speed synchronization step. In this way, according to the gear shifting control method, the problems of mistaken interruption and accidental acceleration of the vehicle possibly caused by the scheme in the prior art can be solved. Furthermore, the invention further provides a gear shifting control device adopting the gear shifting control method, and the gear shifting control device also has the same effect.

Description

Gear shift control method and gear shift control device for vehicle power system Technical Field

[0001] The present application relates to the field of vehicles, and more specifically to a shift control method for a vehicle power system and a shift control device using the shift control method. Background Art

[0002] Figure 1 shows a schematic topological diagram of a hybrid powertrain system for a vehicle. The hybrid powertrain includes an engine (ICE), an electric motor (EM), a clutch (C), and a transmission (T). The output shaft of the engine (ICE) is controllably transmission-coupled to the motor shaft of the electric motor (EM) via the clutch (C). When the clutch (C) is engaged, the output shaft of the engine (ICE) and the motor shaft of the electric motor (EM) are transmission-coupled; when the clutch (C) is disengaged, the output shaft of the engine (ICE) and the motor shaft of the electric motor (EM) are transmission-coupled. The motor shaft of the electric motor (EM) is directly coaxially connected to the input shaft (S) of the transmission (T), ensuring a constant transmission connection between the motor shaft (S) and the input shaft (S) of the transmission (T). In addition to the input shaft (S), the transmission (T) also includes multiple synchronizers and gear pairs for implementing corresponding gear positions. This hybrid powertrain implements a so-called P2 architecture.

[0003] For the vehicle powertrain illustrated in Figure 1 , conventional shift control methods are typically employed to implement gear shifts. In summary, as shown in Figure 2A , this conventional shift control method includes a first torque control step, a disengagement step, a speed synchronization step, an engagement step, and a second torque control step. The following example illustrates a shift from a first gear pair consisting of gears G11 and G12 to a second gear pair consisting of gears G21 and G22 in a transmission T, and further describes this shift control method with reference to Figures 2A and 2B .

[0004] After a shift is initiated using the shift control method shown in Figure 2A , the first torque control step is executed, and the shift process enters phase S1, shown in Figure 2B . During phase S1, the vehicle's powertrain control unit (HCU) sends a torque request to the vehicle's electric motor control unit (MCU). The MCU controls the torque of the electric motor (EM), gradually decreasing it to zero by the end of phase S1. During phase S1, the actual speed of the electric motor (EM) remains consistent with the target speed, and the vehicle's speed increases slightly. Furthermore, at the start of phase S1, the powertrain control unit (HCU) has already set the target gear of synchronizer A from gear G11 to G21. However, the HCU has not yet sent a signal to the transmission control unit (GCU) to control the shift fork. Therefore, the target fork position, the monitored fork position signal, and the actual fork position all indicate that synchronizer A is still engaged with gear G11.

[0005] Furthermore, after the motor control unit MCU feeds back to the powertrain control unit HCU that the actual torque of the motor EM is 0, the disengagement step is started, and the shifting process enters the S2 stage shown in Figure 2B. In the S2 stage, the torque of the motor EM remains at 0. In the S2 stage, the actual speed of the motor EM and the target speed remain consistent, and the speed of the vehicle remains roughly unchanged. In addition, when the S2 stage begins, the powertrain control unit HCU sends the target fork position to the vehicle's transmission control unit GCU, and the transmission control unit GCU controls the synchronizer A based on the target fork position, so that the synchronizer A is disengaged from the gear G11. Therefore, when the S2 stage ends, the monitored fork position signal and the actual fork position both indicate that the synchronizer A is already in a neutral state that is not engaged with any gear.

[0006] Furthermore, after the transmission control unit (GCU) reports to the powertrain control unit (HCU) that synchronizer A is in a neutral state, the speed synchronization step begins, and the shift process enters phase S3, shown in Figure 2B. During phase S3, the powertrain control unit (HCU) sends a speed request to the vehicle's electric motor (EM) control unit (MCU). The MCU controls the torque of the electric motor (EM). By changing the torque of the electric motor (EM), the speed of the electric motor (EM) is increased, and the torque of the electric motor (EM) is reduced to zero at the end of phase S3. During phase S3, the target speed of the electric motor (EM) can be calculated using the speed of the output shaft of the transmission T and the gear ratio of the second gear pair, or by directly monitoring the speed of gear G21, the target gear in the second gear pair. The actual speed of the electric motor (EM) is less than the target speed of the electric motor (EM), and a curve corresponding to the speed control is set to gradually approach the target speed. During phase S3, the vehicle speed remains approximately constant. Furthermore, at the start of phase S3, the target shift fork position, the monitored shift fork position signal, and the actual shift fork position all indicate that synchronizer A is in a neutral state, not engaged with any gear. Furthermore, after the speed synchronization step is initiated, the shift control method simultaneously counts time. If it is determined that the time elapsed during the S3 phase exceeds a predetermined threshold and the actual speed of the electric motor EM is inconsistent with the target speed (which may be greater than a predetermined speed difference), a problem with the speed synchronization step is determined, and the speed synchronization step needs to be interrupted for correction and adjustment.

[0007] Furthermore, after the speed synchronization step is successfully completed so that the actual speed of the motor EM is consistent with the target speed, the engagement step is started, and the shifting process enters the S4 stage shown in Figure 2B. In the S4 stage, the torque of the motor EM is maintained at 0. In the S4 stage, the actual speed of the motor EM is consistent with the target speed, and the speed of the vehicle is slightly reduced. In addition, when the S4 stage begins, the power system control unit HCU sends the target fork position to the vehicle's transmission control unit GCU, and the transmission control unit GCU controls the synchronizer A based on the target fork position, so that the synchronizer A is engaged with the gear G21. Therefore, when the S4 stage ends, the monitored fork position signal and the actual fork position both indicate that the synchronizer A is already in a state of engagement with the gear G21.

[0008] Furthermore, after the transmission control unit (GCU) reports to the powertrain control unit (HCU) that synchronizer A is engaged with gear G21, the second torque control step begins, and the shift process enters stage S5, shown in Figure 2B. During stage S5, the vehicle powertrain control unit (HCU) sends a torque request to the vehicle's electric motor control unit (MCU). The MCU controls the torque of the electric motor (EM) so that the torque of the electric motor (EM) gradually increases to a predetermined value. During stage S5, the actual speed of the electric motor (EM) remains consistent with the target speed, and the vehicle's speed gradually increases. During stage S5, the powertrain control unit (HCU) maintains synchronizer A's target gear at gear G21. The target shift fork position, the monitored shift fork position signal, and the actual shift fork position all indicate that synchronizer A is engaged with gear G21. Thus, the entire downshift process from the first gear pair to the second gear pair is completed using the above-described shift control method.

[0009] The aforementioned conventional shift control method may present the following issues. On the one hand, if the speed difference between the actual and target speeds of the electric motor (EM) is too large at the beginning of the speed synchronization step, and the electric motor's torque output capacity is insufficient (e.g., due to a low battery charge), the speed synchronization step may take too long (e.g., the duration of stage S3 is too long). Consequently, the prior art shift control method's use of a time threshold for logical judgment may result in an unintended interruption of the shift process. On the other hand, if the torque output capacity of the electric motor (EM) is excessive during the speed synchronization step, the vehicle may experience unintended acceleration during the speed synchronization step, potentially leading to serious consequences. FIG2C illustrates an example of a possible situation. As shown in FIG2C , although the transmission control unit GCU feeds back to the power system control unit HCU that the synchronizer A is in a neutral state at the beginning of the S3 stage, if the actual shift fork position is such that the synchronizer A has not actually completed disengagement from the gear G11 and the synchronizer A is still engaged with the gear G11, then, after controlling the torque of the motor EM to increase the speed of the motor EM, both the target speed and the actual speed of the motor EM increase, making it difficult to achieve consistency between the actual speed of the motor EM and the target speed. Instead, the vehicle may accelerate unexpectedly due to the increased output torque of the motor EM, which may cause safety problems.

[0010] Summary of the Invention

[0011] This application was developed in light of the aforementioned shortcomings of hybrid power systems. One objective of this application is to provide a shift control method for a vehicle power system that avoids potential erroneous interruptions and unintended vehicle acceleration during the speed synchronization step. Another objective of this application is to provide a shift control device that utilizes the aforementioned shift control method.

[0012] In order to achieve the above objectives, this application adopts the following technical solutions.

[0013] The present application provides a shift control method for a vehicle power system, wherein the vehicle power system includes a motor and a transmission, wherein the motor is always in driving connection with an input shaft of the transmission, and the shift control method includes:

[0014] The speed synchronization step controls the torque of the motor so that the actual speed of the motor gradually approaches the target speed; before the actual speed is consistent with the target speed, the expected speed difference and the speed reference value of the motor are obtained. If the absolute value of the expected speed difference is greater than the absolute value of the speed reference value, the speed synchronization step is interrupted.

[0015] In an optional solution, a value calculated using the torque of the motor, the drag torque of the input shaft, and the rotational inertia of both the motor and the input shaft is used as the expected speed difference of the motor.

[0016] In another optional solution, the offset rotational speed is set to any value between -100 rpm and -300 rpm, and the sum of the result value and the offset rotational speed is used as the expected rotational speed difference.

[0017] In another optional solution, the shifting process is shifting from the first gear pair to the second gear pair, and the result value calculated using the vehicle speed, the transmission ratio of the first gear pair and the transmission ratio of the second gear pair is used as the speed reference value.

[0018] In another optional solution, the offset value is set to any value between 0.95 and 1.05, and the product of the offset value as a weighting coefficient and the result value is used as the speed reference value.

[0019] In another optional solution, the speed of the vehicle is the speed of the vehicle at the moment when the transmission feeds back a signal that the synchronizer is switched to a neutral state; or

[0020] The speed of the vehicle is the speed of the vehicle at a current moment when a predetermined time has passed after the transmission feeds back a signal that the synchronizer is switched to the neutral state.

[0021] In another optional solution, when the speed of the vehicle is the speed at the current moment, the expected speed difference and the speed reference value of the motor are acquired in real time after the transmission feeds back a signal indicating that the synchronizer has switched to a neutral state.

[0022] In another optional solution, the shift control method further includes a correction step after interrupting the speed synchronization step, in which the torque of the motor is reduced to a predetermined value.

[0023] The present application also provides a shift control device as follows, which adopts the shift control method described in any one of the above technical solutions.

[0024] In an optional solution, a speed synchronization unit is included, which can obtain the expected speed difference and speed reference value of the motor in the process of gradually making the actual speed of the motor approach the target speed, and determine the size relationship between the absolute value of the expected speed difference and the absolute value of the speed reference value.

[0025] In an optional solution, the speed synchronization unit includes:

[0026] a calculation module capable of obtaining a desired speed difference and a speed reference value of the motor through calculation; and

[0027] A judgment module capable of judging the magnitude relationship between the absolute value of the expected speed difference and the absolute value of the speed reference value,

[0028] The calculation module and the judgment module are electrically connected, so that signals can be transmitted between the calculation module and the judgment module.

[0029] In an optional solution, when the judgment module determines that the absolute value of the expected speed difference is greater than the absolute value of the speed reference value, the judgment module generates an interrupt signal to interrupt the process of gradually approaching the actual speed of the motor to the target speed.

[0030] In an optional solution, the shift control device further includes a correction unit, which is capable of reducing the torque of the motor to a predetermined value after the process in which the actual speed of the motor gradually approaches the target speed is interrupted.

[0031] In another alternative, the calculation module uses the torque of the motor, the drag torque of the input shaft, and the moment of inertia of both the motor and the input shaft to calculate a value as the desired speed difference of the motor. In a further alternative, the calculation module uses the sum of the calculated value and an offset speed as the desired speed difference, where the offset speed is any value between -100 rpm and -300 rpm.

[0032] In another alternative embodiment, when the shift process is from the first gear pair to the second gear pair, the calculation module uses the vehicle speed, the transmission ratio of the first gear pair, and the transmission ratio of the second gear pair to calculate a result value as the speed reference value. In a further alternative embodiment, the calculation module uses the offset value as a weighting coefficient and multiplies the result value by the product to determine the speed reference value, where the offset value is any value between 0.95 and 1.05.

[0033] By adopting the above-mentioned technical solution, the present application provides a shift control method for a vehicle power system. In the speed synchronization step of the shift control method of the present application, the expected speed difference and the speed reference value are calculated using vehicle parameters. The speed synchronization step is then judged based on the magnitude relationship between the absolute value of the expected speed difference and the absolute value of the speed reference value. This replaces the prior art shift control method that uses a time threshold to judge whether the speed synchronization step is successfully executed. In this way, the shift control method of the present application can avoid the problems of false interruption and unintended vehicle acceleration that may be caused by the prior art solution. Furthermore, the present application also provides a shift control device that adopts the above-mentioned shift control method, which also has the same effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG1 is a schematic diagram showing a topological structure of a hybrid power system having a P2 architecture.

[0035] FIG. 2A is a flow chart illustrating a prior art shift control method for a vehicle power system.

[0036] FIG2B is a schematic diagram showing curves of various parameters changing over time during a downshift performed by the hybrid system in FIG1 using a conventional shift control method, wherein the horizontal axis in the figure represents time.

[0037] FIG2C is a schematic diagram showing curves of various parameters changing over time when a fault occurs during downshifting performed by the hybrid system in FIG1 using the prior art shift control method, wherein the fault is caused by the synchronizer not being disengaged from the gear before the shift. The horizontal axis in the figure represents time.

[0038] FIG3A is a flowchart illustrating a shift control method of a vehicle power system according to an embodiment of the present application.

[0039] Figure 3B is a schematic diagram showing curves of various parameters changing over time when a fault occurs during downshifting performed by the hybrid system in Figure 1 using the shift control method of an embodiment of the present application, wherein the fault is caused by the synchronizer not being disengaged from the gear before the shift. The horizontal axis in the figure represents time.

[0040] FIG4 is a structural block diagram showing a shift control device according to an embodiment of the present application.

[0041] Description of Reference Numerals

[0042] ICE engine; EM motor; C clutch; T transmission; A synchronizer; G11, G12, G21, G22 gears;

[0043] HCU power system control unit; MCU motor control unit; GCU transmission control unit; SCU shift control unit; COM calculation module; JM judgment module; MU correction unit. Specific embodiments

[0044] The following describes exemplary embodiments of the present application with reference to the accompanying drawings. It should be understood that these specific descriptions are only used to teach those skilled in the art how to implement the present application, and are not intended to exhaust all possible methods of the present application, nor to limit the scope of the present application.

[0045] In this application, "drive coupling" refers to a connection between two components that can transmit torque, and unless otherwise specified, includes direct or indirect connections between the two components. "Always drive coupling" means that the two components always maintain a drive coupling state, and "controlled drive coupling" means that the two components can be drive coupled and released.

[0046] In this application, "rotational speed" may refer to the number of revolutions a rotating object makes around its central axis per unit time, for example, its unit may be rpm (revolutions per minute); "speed" may refer to the ratio of the displacement of a moving object to time, for example, its unit may be m / s, km / h, etc.

[0047] In this application, the synchronizer's outer gear sleeve is driven by the shift fork. When the outer gear sleeve is engaged with the corresponding gear under the drive of the shift fork, the synchronizer is in the engaged state. When the outer gear sleeve is not engaged with any gear under the drive of the shift fork, the synchronizer is in the neutral state.

[0048] The following will describe a shift control method for a vehicle power system according to an embodiment of the present application based on the accompanying drawings.

[0049] In summary, as shown in FIG3A , the shift control method includes a first torque control step, a disengagement step, a speed synchronization step, an engagement step, and a second torque control step. Still referring to the hybrid powertrain system of the vehicle of FIG1 , the shift control method according to the present application will be described in detail using the process of transmission T performing a downshift from the first gear pair consisting of gears G11 and G12 to the second gear pair consisting of gears G21 and G22 as an example, with reference to FIG3A and FIG3B .

[0050] After a shift is initiated using the shift control method shown in Figure 3A , the first torque control step is executed, and the shift process enters phase S1, shown in Figure 3B . During phase S1, the vehicle's powertrain control unit (HCU) sends a torque request to the vehicle's electric motor control unit (MCU). The MCU controls the torque of the electric motor (EM), gradually decreasing it to zero by the end of phase S1. During phase S1, the actual speed of the electric motor (EM) remains consistent with the target speed, and the vehicle's speed increases slightly. Furthermore, at the start of phase S1, the powertrain control unit (HCU) has already set the target gear of synchronizer A from gear G11 to G21. However, the HCU has not yet sent a signal to the transmission control unit (GCU) to control the shift fork. Therefore, the target fork position, the monitored fork position signal, and the actual fork position all indicate that synchronizer A is engaged with gear G11.

[0051] Furthermore, after the motor control unit (MCU) reports that the actual torque of the electric motor (EM) is zero to the powertrain control unit (HCU), the disengagement step begins, and the shift process enters phase S2, shown in Figure 3B. During phase S2, the torque of the electric motor (EM) remains at zero, the actual speed of the electric motor (EM) remains consistent with the target speed, and the vehicle's speed remains approximately constant. Furthermore, when phase S2 begins, the powertrain control unit (HCU) transmits a target shift fork position to the vehicle's transmission control unit (GCU). Based on the target shift fork position, the GCU controls synchronizer A to disengage it from gear G11. Therefore, at the end of phase S2, if all components have successfully executed the above process, the monitored shift fork position signal and the actual shift fork position will both indicate that synchronizer A is in a neutral state, not engaged with any gear. However, to illustrate the error correction mechanism of the shift control method of this application during the speed synchronization step, Figure 3B illustrates that synchronizer A has not actually disengaged from gear G11, but the monitored shift fork position signal erroneously indicates that synchronizer A has disengaged from gear G11.

[0052] Furthermore, after the transmission control unit (GCU) reports to the powertrain control unit (HCU) that synchronizer A is in a neutral state, the speed synchronization step begins, and the shift process enters stage S3, shown in Figure 3B. During stage S3, the powertrain control unit (HCU) sends a speed request to the vehicle's electric motor (EM) control unit, which controls the torque of the electric motor (EM). By changing the torque of the electric motor (EM), the speed of the electric motor (EM) can be increased. During stage S3, the target speed of the electric motor (EM) can be calculated using the speed of the output shaft of the transmission T and the gear ratio of the second gear pair, or directly monitored by monitoring the speed of gear G21, the target gear in the second gear pair. The actual speed of the electric motor (EM) is less than the target speed of the electric motor (EM), and a curve corresponding to the speed control is set to gradually approach the target speed. Figure 3B illustrates a fault condition during the execution of the shift control method. That is, although the transmission control unit (GCU) reports to the powertrain control unit (HCU) that synchronizer A is in a neutral state at the beginning of stage S3, the actual shift fork position indicates that synchronizer A has not yet fully disengaged from gear G11, and therefore synchronizer A remains engaged with gear G11. In this way, after the torque of the motor EM is controlled to control the motor EM to accelerate, the actual rotation speed of the motor EM cannot be made consistent with the target rotation speed.

[0053] In order to cope with this situation, as shown in Figure 3A, in the gear shift control method of the present application, after the speed synchronization step is started, the expected speed difference is calculated using the torque of the motor EM, the drag torque of the input shaft S, and the rotational inertia of both the motor EM and the input shaft S, and the speed reference value is calculated using the speed of the vehicle, the transmission ratio of the first gear pair, and the transmission ratio of the second gear pair. The speed synchronization step is interrupted when the expected speed difference is greater than the speed reference value before the actual speed of the motor EM is consistent with the target speed.

[0054] Specifically, let the torque of the motor EM be T M (Unit is N·m, for example), the drag torque of the input shaft S is T f (unit is N·m, for example), the moment of inertia of the motor EM and the input shaft S is J (unit is kg·m 2 ), the offset speed is N O If the offset speed is any value between -100 rpm and -300 rpm, then the expected speed difference N(t) (e.g., in rpm) after a time t (e.g., in seconds) has passed since the transmission T fed back a signal that the synchronizer A switched to a neutral state in the speed synchronization step is expressed as:

[0055]

[0056] In the above formula, This is the conversion factor used for speed unit conversion. Since N(t) is expressed in rpm (revolutions per minute), and the result obtained by integrating torque is expressed in rad / s (radians per second), this conversion factor is required for conversion.

[0057] Assuming the vehicle speed is v (e.g., km / h), the transmission ratio of the first gear pair is r1, the transmission ratio of the second gear pair is r2, the radius of the wheel is R (e.g., m), and the offset value is f(v), and the offset value is any value between 0.95 and 1.05, then the reference value N(th) (e.g., rpm) is expressed as:

[0058]

[0059] The vehicle speed v can be the vehicle speed at the moment when the transmission T feeds back a signal that synchronizer A has switched to a neutral state, in which case the reference value N(th) is effectively a constant value. Alternatively, the vehicle speed v can be the vehicle speed at the current moment, time t, after the transmission T feeds back a signal that synchronizer A has switched to a neutral state, in which case the reference value N(th) is effectively a variable value. Furthermore, the transmission ratio of the first gear pair is the total transmission ratio of the torque transmission path corresponding to the first gear pair in the entire transmission system, and the transmission ratio of the second gear pair is the total transmission ratio of the torque transmission path corresponding to the second gear pair in the entire transmission system.

[0060] In the above formula, This is the conversion factor used for speed unit conversion. Since the vehicle speed v is in km / h and the reference value N(th) is in rpm, the above conversion factor is required for conversion.

[0061] The shift control method according to one embodiment of the present application also includes a correction step. Once the speed synchronization step is interrupted according to the aforementioned logic, the correction step is executed, and the shift process enters phase S6 shown in FIG3B . When phase S6 begins, the powertrain control unit (HCU) changes the target gear. During phase S6, the torque of the electric motor (EM) is reduced to a predetermined value (optionally, 0), and the target shift fork position signal is adjusted based on the target gear. This prevents unintended vehicle acceleration.

[0062] Furthermore, if the speed synchronization step is successfully completed, aligning the actual speed of the electric motor (EM) with the target speed, the engagement step and the second torque control step are sequentially executed, as shown in Figure 3A . In the engagement step, synchronizer A engages the target gear, as shown in step S4 in Figure 2B . In the second torque control step, the torque of the electric motor (EM) is increased, as shown in step S5 in Figure 2B . This torque is then transmitted to the wheels via the second gear pair. In this manner, the entire downshift process from the first gear pair to the second gear pair is completed using the above-described shift control method.

[0063] The technical solution of the present application has been described in detail in the above specific embodiments, and supplementary explanations are given below.

[0064] i. It can be understood that by utilizing the logical judgment between the above-mentioned expected speed difference and the speed reference value, the gear shift control method according to the present application can not only avoid the problem of excessive torque of the motor EM causing unexpected acceleration of the vehicle as described in the above-mentioned embodiment, but also avoid the problem of insufficient torque of the motor EM causing erroneous interruption of the gear shift process.

[0065] ii. It can be understood that before the hybrid system shown in FIG. 1 is shifted using the shift control method according to the present application, the clutch C can be in a disengaged state, so that the engine ICE and the input shaft S of the transmission T are decoupled.

[0066] iii. It will be appreciated that the vehicle powertrain capable of employing the shift control method according to the present application is not limited to the hybrid powertrain having the P2 architecture shown in FIG1 , but may also be other powertrains. For example, it may be an electric axle drive system in which the engine is omitted and the motor is permanently drivingly coupled to the input shaft of the transmission.

[0067] iv. In the above specific embodiments, it is described that the downshift process is performed using the shift control method of the present application. It can be understood that when the upshift process is performed using the shift control method of the present application, if the absolute value of the expected speed difference before the actual speed is consistent with the target speed is greater than the absolute value of the reference value, the speed synchronization step is interrupted.

[0068] v. In the shift control method according to one embodiment of the present application, the offset speed is a parameter used to modify the final value of the desired speed difference. The offset speed value can be determined based on safety requirements. The offset value can be an empirical parameter, and the offset value can be selected based on vehicle speed, with the offset value increasing as the vehicle speed increases. In an optional embodiment of the shift control method of the present application, the offset speed and offset value can be omitted, and the desired speed difference and speed reference value can be calculated using the following expressions accordingly.

[0069]

[0070]

[0071] In addition, in the present application, the value of π may be 3.14, or a more precise value may be used for the sake of accuracy.

[0072] vi. The present application also provides a shift control device that adopts a shift control method according to an embodiment of the present application or implements a shift control method according to an embodiment of the present application. The shift control device may include a speed synchronization unit and a correction unit that are independent of other control units of the vehicle, and may also include a speed synchronization unit and a correction unit that are integrated with other control units of the vehicle.

[0073] When the speed synchronization unit and the correction unit are independent of other control units, as shown in Figure 4, the shift control device may include an electrically conductive power system control unit HCU, a transmission control unit GCU, a motor control unit MCU, a speed synchronization unit SCU and a correction unit MU, which can communicate signals with each other.

[0074] The transmission control unit GCU can monitor the status of the transmission's synchronizer and can provide feedback on the status of the synchronizer. The motor control unit MCU can monitor the torque and speed of the motor and can provide feedback on the torque and speed of the motor, and can also control the torque of the motor EM to adjust the speed of the motor EM. The powertrain control unit HCU is electrically connected to the transmission control unit GCU and the motor control unit MCU. The powertrain control unit HCU can receive the status signal of the synchronizer fed back by the transmission control unit GCU, and can send a signal to the transmission control unit GCU to change the state of the synchronizer. The powertrain control unit HCU can receive the torque and speed of the motor fed back by the motor control unit MCU, and can send a signal to the motor control unit MCU to adjust the speed of the motor by controlling the torque of the motor. The powertrain control unit HCU, the transmission control unit GCU, and the motor control unit MCU can adopt the corresponding control units already available in the vehicle.

[0075] During the execution of the shift control method of the present application, the speed synchronization unit SCU is capable of receiving the required parameters sent by the power system control unit HCU to calculate the expected speed difference and the speed reference value, and when it is determined that the absolute value of the expected speed difference is greater than the absolute value of the speed reference value, the speed synchronization unit is capable of generating an interrupt signal to interrupt the speed synchronization step. More specifically, the speed synchronization unit SCU may include a calculation module COM that obtains the expected speed difference and the speed reference value of the motor by calculation, and a judgment module JM that judges the magnitude relationship between the absolute value of the expected speed difference and the absolute value of the speed reference value. The calculation module COM and the judgment module JM are electrically connected, so that signal transmission can be carried out between the calculation module COM and the judgment module JM. It can be understood that in the process of the calculation module COM calculating the expected speed difference and the speed reference value, the parameters and calculation method described above can be used for calculation. For example, the calculation module uses the motor torque, the input shaft drag torque, and the moment of inertia of both the motor and the input shaft to calculate the desired motor speed difference. Furthermore, the calculation module COM uses the sum of this calculated value and an offset speed as the desired speed difference, with the offset speed being a value anywhere between -100 rpm and -300 rpm. Furthermore, when shifting from the first gear pair to the second gear pair, the calculation module COM uses the vehicle speed, the gear ratio of the first gear pair, and the gear ratio of the second gear pair as the speed reference value. Furthermore, the calculation module COM uses the product of this calculated value and the offset value as a weighting factor to determine the speed reference value, with the offset value being a value anywhere between 0.95 and 1.05. Accordingly, if the judgment module JM determines that the absolute value of the desired speed difference is greater than the absolute value of the speed reference value, the judgment module JM generates an interrupt signal to interrupt the process of gradually approaching the actual motor speed to the target speed.

[0076] During the execution of the shift control method of the present application, after an interrupt signal is transmitted to the powertrain control unit (HCU), the HCU can interrupt the speed synchronization step by controlling the torque of the electric motor (EM) through the electric motor control unit (MCU). Subsequently, the correction unit (MU) generates a predetermined torque required for the electric motor (EM) to reach after the interruption. The correction unit (MU) then controls the torque of the electric motor (EM) or controls the torque of the electric motor (EM) through the electric motor control unit (MCU) to achieve the predetermined torque. Alternatively, the predetermined torque can be zero.

[0077] In addition, when the speed synchronization unit and the correction unit are integrated with other control units, in an optional solution, the functions implemented by the speed synchronization unit and the correction unit can be integrated into the power system control unit.

Claims

1. A shift control method for a vehicle power system, the vehicle power system comprising an electric motor (EM) and a transmission (T), the electric motor (EM) being permanently drivingly coupled to an input shaft (S) of the transmission (T), the shift control method comprising: a speed synchronization step of controlling the torque of the electric motor (EM) so that the actual speed of the electric motor (EM) gradually approaches the target speed; Before the actual speed is consistent with the target speed, an expected speed difference and a speed reference value of the motor are obtained. If the absolute value of the expected speed difference is greater than the absolute value of the speed reference value, the speed synchronization step is interrupted.

2. The shift control method according to claim 1, characterized in that: A value calculated using the torque of the motor (EM), the drag torque of the input shaft (S), and the rotational inertia of both the motor (EM) and the input shaft (S) is used as a desired speed difference of the motor (EM).

3. The shift control method according to claim 2, characterized in that: Assume that the offset rotational speed is any value between -100 rpm and -300 rpm, and take the sum of the result value and the offset rotational speed as the expected rotational speed difference.

4. The shift control method according to claim 1, wherein: The shifting process is to shift from a first gear pair (G11, G12) to a second gear pair (G21, G22), and a value calculated using the vehicle speed, the transmission ratio of the first gear pair (G11, G12), and the transmission ratio of the second gear pair (G21, G22) is used as a speed reference value.

5. The shift control method according to claim 4, characterized in that: The offset value is set to any value between 0.95 and 1.05, and the product of the offset value as a weighting coefficient and the result value is used as the speed reference value.

6. The shift control method according to claim 4 or 5, characterized in that: The speed of the vehicle is the speed of the vehicle at the moment when the transmission (T) feeds back a signal that the synchronizer (A) is switched to a neutral state; or The speed of the vehicle is the speed of the vehicle at a current moment when a predetermined time has passed after the transmission (T) feeds back a signal that the synchronizer (A) is switched to a neutral state.

7. The shift control method according to claim 6, characterized in that: When the speed of the vehicle is the current speed, the expected speed difference and the speed reference value of the motor are acquired in real time after the transmission (T) feeds back a signal indicating that the synchronizer (A) is switched to a neutral state.

8. The shift control method according to any one of claims 1 to 7, characterized in that: The shift control method further includes, after interrupting the speed synchronization step, a correction step of reducing the torque of the electric motor (EM) to a predetermined value.

9. A gear shift control device, characterized in that: The shift control method according to any one of claims 1 to 8 is adopted.

10. The shift control device according to claim 9, characterized in that: The invention comprises a speed synchronization unit (SCU), which is capable of obtaining a desired speed difference and a speed reference value of the motor (EM) in the process of gradually bringing the actual speed of the motor (EM) closer to the target speed, and determining the magnitude relationship between the absolute value of the desired speed difference and the absolute value of the speed reference value.

11. The shift control device according to claim 10, wherein: The speed synchronization unit (SCU) includes: a calculation module (COM), capable of obtaining a desired speed difference and a speed reference value of the motor through calculation; and a judgment module (JM), which is capable of judging the magnitude relationship between the absolute value of the expected speed difference and the absolute value of the speed reference value, The calculation module (COM) and the judgment module (JM) are electrically connected, so that signals can be transmitted between the calculation module (COM) and the judgment module (JM).

12. The shift control device according to claim 11, characterized in that: When the judgment module (JM) judges that the absolute value of the expected speed difference is greater than the absolute value of the speed reference value, the judgment module (JM) generates an interrupt signal to interrupt the process of gradually approaching the actual speed of the motor (EM) to the target speed.

13. The shift control device according to any one of claims 10 to 12, characterized in that: The shift control device further includes a correction unit (MU) capable of reducing the torque of the electric motor (EM) to a predetermined value after a process in which the actual speed of the electric motor (EM) gradually approaches the target speed is interrupted.

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