Gear shift control method and apparatus for a vehicle drive system
Patent Information
- Application Number
- DE112022007770
- Authority / Receiving Office
- DE · DE
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2022-09-14
- Publication Date
- 2025-07-24
Smart Images
Figure 00000000_0000_ABST
Abstract
Description
TECHNICAL FIELDThe present application relates to the field of vehicles, and more particularly to a gear shift control method for a vehicle drive system and a gear shift control device applying this gear shift control method.PRIOR ARTFIG. 1 shows a schematic topology illustration of a hybrid drive system of a vehicle. The hybrid drive system includes an engine ICE, an electric motor EM, a clutch C, and a transmission T. An output shaft of the ICE is controllably connected to a motor shaft of the electric motor EM by means of the clutch C in a transmission-like manner. With clutch C engaged, the output shaft of the ICE is connected in a gear-like manner to a motor shaft of the electric motor EM. With clutch C disengaged, the output shaft of the ICE is disconnected from the motor shaft of the electric motor EM. The motor shaft of the electric motor EM is directly connected to an input shaft S of the transmission T in a coaxial manner, so that the motor shaft of the electric motor EM is always connected to the input shaft S of the transmission T in a transmission-like manner. In addition to the input shaft S, the transmission T includes a plurality of synchronizers and gear pairs that realize respective gear stages. In this hybrid drive system, a so-called P2 architecture is realized.In the vehicle drive system exemplified in FIG. 1, the prior art gear shift control method is usually used during the gear shift process. In general, as shown in FIG. 2A, the gear shift control method according to the related art includes a first torque control step, a disengagement step, a speed synchronization step, an engagement step, and a second torque control step. Taking a gear shift process in which a first gear pair consisting of gears G 11 and G 12 is shifted to a second gear pair consisting of gears G 21 and G 22 using transmission T, the gear shift control method will be specifically described in combination with FIGS. 2A and 2B.When the gear shift control method shown in FIG. 2A is used to start the gear shift process, the first torque control step is first executed, and the gear shift process enters phase S 1 shown in FIG. 2B. In phase S 1, a hybrid control unit HCU of the vehicle sends a torque request to an engine control unit MCU of the vehicle, and the engine control unit MCU controls the torque of the electric motor EM so that the torque of the electric motor EM gradually decreases and reaches 0 at the end of phase S 1. In phase S 1, the actual rotational speed of the electric motor EM remains consistent with the target rotational speed, and the vehicle speed slightly increases. Moreover, when phase S 1 starts, the hybrid control unit HCU has already set the target gear of the synchronizer A from gear G 11 to G 21, but the hybrid control unit HCU has not sent a signal to the transmission control unit GCU to control the fork movement. Therefore, a target fork position, a monitored fork position signal and an actual fork position all indicate that the synchronizer A is still in an engaged state with the gear G 11.Further, after the engine control unit MCU has given feedback to the hybrid control unit HCU that the actual torque of the electric motor EM is 0, the disengagement step is executed, and the gear shift process occurs in phase S 2 shown in FIG. 2B. In phase S 2, the torque of the electric motor EM remains at 0. In phase S 2, the actual rotational speed of the electric motor EM remains consistent with the setpoint rotational speed, and the vehicle speed remains approximately unchanged. Moreover, at the beginning of phase S 2, the hybrid control unit HCU transmits the target fork position to the transmission control unit GCU of the vehicle, 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 G 11. Therefore, at the end of phase S 2, both the monitored fork position signal and the actual fork position indicate that synchronizer A is in a neutral state in which synchronizer A is not engaged with any gear.Further, after the transmission control unit GCU has given feedback to the hybrid control unit HCU that the synchronizer A is in the neutral state, the rotation speed synchronizing step is executed, and the gear shifting process occurs in phase S 3 shown in FIG. 2B. In phase S 3, the hybrid control unit HCU sends a speed request to the engine control unit MCU of the vehicle, and the engine control unit MCU controls the torque of the electric motor EM. By changing the torque of the electric motor EM, the rotational speed of the electric motor EM can be increased, wherein the torque of the electric motor EM falls back to 0 at the end of phase S 3. In phase S 3, the target rotational speed of the electric motor EM may be calculated by using the rotational speed of the output shaft of the transmission T via the gear ratio of the second gear pair, or may be obtained by directly monitoring the rotational speed of the gear G 21 used as the target gear in the second gear pair. The actual rotational speed of the electric motor EM is smaller than the target rotational speed of the electric motor EM, and by setting a curve corresponding to the control rotational speed, the actual rotational speed gradually approaches the target rotational speed. In phase S 3, the vehicle speed remains approximately unchanged. Moreover, at the beginning of phase S 3, the target fork position, the monitored fork position signal, and the actual fork position all indicate that the synchronizer A is in the neutral state in which the synchronizer A is not engaged with any gear. Moreover, after the speed synchronizing step is started in the gear shift control method, a timing control is also performed. As soon as it has been determined that the time required in phase S 3 is longer than a predefined threshold value and the actual rotational speed of the electric motor EM does not match the setpoint rotational speed, wherein the difference can be greater than a predefined rotational speed difference, it is determined that a problem exists with the rotational speed synchronization step, and the rotational speed synchronization step must be interrupted for correction and adaptation.Further, after the speed synchronization step is successfully performed so that the actual speed of the electric motor EM coincides with the target speed, the engagement step is performed, and the gear shift process occurs in phase S 4 shown in FIG. 2B. In phase S 4, the torque of the electric motor EM remains at 0. In phase S 4, the actual rotational speed of the electric motor EM remains consistent with the target rotational speed, and the vehicle speed decreases slightly. Moreover, at the beginning of phase S 4, the hybrid control unit HCU transmits the target fork position to the transmission control unit GCU of the vehicle, 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 G 21. Therefore, at the end of phase S 4, both the monitored fork position signal and the actual fork position indicate that the synchronizer A is in an engaged state with the gear G 21.Further, after the transmission control unit GCU has given feedback to the hybrid control unit HCU that the synchronizer A is in an engaged state with the gear G 21, the second torque control step is executed, and the gear shift process occurs in phase S 5, as shown in FIG. 2B. In Phase S 5, the hybrid control unit HCU of the vehicle sends a torque request to the engine control unit MCU of the vehicle, and the engine control unit MCU controls the torque of the electric motor EM so that the torque of the electric motor EM gradually increases to a predetermined value. In phase S 5, the actual rotational speed of the electric motor EM remains consistent with the target rotational speed, and the vehicle speed gradually increases. In phase S 5, the hybrid control unit HCU maintains the target gear of the synchronizer A as the gear G 21, and the target fork position, the monitored fork position signal, and the actual fork position all indicate that the synchronizer A is in an engagement state with the gear G 21. In this way, the entire downshift process from the first gear pair to the second gear pair is completed using the above-mentioned gear shift control method.In the above-described gear shift control method, the following problems may occur. On the one hand, when the rotational speed difference between the actual rotational speed of the electric motor EM and the target rotational speed is too large at the beginning of the rotational speed synchronizing step and the electric motor EM does not have sufficient torque output capability (for example, a case of insufficient battery power), the time required to perform the rotational speed synchronizing step takes too long, Phase S 3 takes too long, and a logical judgment performed using the time threshold according to the existing gear shift control method may result in an undesirable interruption of the gear shift process. On the other hand, if the electric motor EM has excessive torque output during the speed synchronizing step, the vehicle may be subjected to unexpected acceleration during the speed synchronizing step, which may have very severe consequences. FIG. 2C shows an example of such a circumstance. As shown in FIG. 2C, the transmission control unit GCU reports back to the hybrid control unit HCU that the synchronizer A is in the neutral state at the beginning of phase S 3. However, when the actual fork position indicates that the synchronizer A has not yet completed disengagement from the gear G 11, i.e., the synchronizer A is still in an engaged state with the gear G 11, after controlling the torque of the electric motor EM to increase the rotational speed of the electric motor EM, both the target rotational speed and the actual rotational speed of the electric motor EM increase, thereby making it difficult to achieve consistency between the actual rotational speed and the target rotational speed of the electric motor EM. Instead, undesired acceleration of the vehicle may occur due to the increased torque output of the electric motor EM, which may lead to safety problems.CONTENT OF THE INVENTIONThe present application has been made in view of the disadvantages of the above-mentioned hybrid drive system. It is an object of the present application to provide a gear shift control method for a vehicle drive system which can avoid possible erroneous interruptions and unexpected accelerations of the vehicle during the speed synchronization step. Another object of the present application is to provide a gear shift control device that employs the above-mentioned gear shift control method.In order to achieve the above-mentioned purposes, the following technical solutions are provided in the present application.In the present application, there is provided a gear shift control method for a vehicle drive system, wherein the vehicle drive system includes an engine and a transmission, and the engine is always connected in a transmission-like manner to an input shaft of the transmission, the gear shift control method including:a speed synchronizing step for controlling the torque of the motor so that the actual speed of the motor gradually approaches the target speed; and before the actual speed is consistent with the target speed, obtaining the expected speed difference and the speed reference value of the motor; and in the case that the absolute value of the expected speed difference is larger than the absolute value of the speed reference value, stopping the speed synchronizing step.In an optional solution, the torque of the engine, the drag torque of the input shaft, and the rotational inertia of the engine and the rotational inertia of the input shaft are used to calculate the result value as the expected speed difference of the engine.In a further optional solution, the offset rotational speed is set to an arbitrary value between -100 U / min and -300 U / min, and the sum of the result value and the offset rotational speed is used as the expected rotational speed difference.In another optional solution, the gear shift process is a gear shift process from the first gear pair to the second gear pair, and the vehicle speed, the gear ratio of the first gear pair, and the gear ratio of the second gear pair are used to calculate the result value as a rotational speed reference value.In a further optional solution, the offset value is set to an arbitrary value between 0.95 and 1.05 and the product of the offset value and the result value is used as the rotational speed reference value.In another optional solution, the vehicle speed is the speed of the vehicle at just the moment the transmission provides as feedback a signal indicative of a synchronizer having shifted to a neutral state; or the vehicle speed is the current speed of the vehicle after a predetermined time has elapsed since the precise moment the transmission provides as feedback a signal indicative of the synchronizer having shifted to the neutral state.In another optional solution, when the vehicle speed is the current speed, the expected speed difference and the speed reference value of the engine are obtained in real time after the transmission provides a signal as feedback indicating that the synchronizer has shifted to the neutral state.In another optional solution, after the speed synchronizing step is interrupted, the gear shift control method further includes a correction step of reducing the torque of the motor to a predetermined value.In the present application, there is further provided a gear shift control device to which any one of the above-mentioned gear shift control methods is applied.In an optional solution, the gear shift controller includes a speed synchronization unit configured to obtain the expected speed difference of a motor and the speed reference value during a process in which the actual speed of the motor gradually approaches the target speed of the motor, and determine the relationship between the absolute value of the expected speed difference and the absolute value of the speed reference value.In an optional solution, the speed synchronization unit includes:a computer on module configured to calculate the expected speed difference of the motor and the speed reference value; anda judging module configured to judge the relationship between the absolute value of the expected rotational speed difference and the absolute value of the rotational speed reference value,wherein the computer-on module and the evaluation module are electrically connected, thereby enabling signals to be transmitted between the computer-on module and the evaluation module.In an optional solution, when the judging module judges that the absolute value of the expected rotational speed difference is larger than the absolute value of the rotational speed reference value, the judging module generates an interrupt signal to interrupt the process in which the actual rotational speed of the motor gradually approaches the target rotational speed of the motor.In an optional solution, the gear shift control device further includes a modification unit configured to reduce the torque of the engine to a predetermined value after the process in which the actual rotational speed of the engine gradually approaches the target rotational speed of the engine is interrupted.In another optional solution, the computer-on module uses the engine torque, the drag torque of the input shaft, and the rotational inertia of the engine, and the rotational inertia of the input shaft to calculate the result value as the expected speed difference of the engine. In another optional solution, the computer-on module uses the sum of the result value and the offset rotational speed as the expected rotational speed difference, wherein the offset rotational speed is any value between -100 U / min and -300 U / min.In another optional solution, during the gear shifting process from the first gear pair to the second gear pair, the computer-on module uses the vehicle speed, the gear ratio of the first gear pair, and the gear ratio of the second gear pair to calculate the result value as a speed reference value. In a further optional solution, the computer-on module uses the product of the offset value and the result value as a rotational speed reference value, wherein the offset value is an arbitrary value between 0.95 and 1.05.By adopting the above-described technical solutions, according to the present application, a gear shift control method for a vehicle drive system is provided. In the speed synchronization step of the gear shift control method of the present application, vehicle parameters are used to calculate the expected speed difference and the speed reference value, and the relationship between the absolute value of the expected speed difference and the absolute value of the speed reference value is used to judge whether the speed synchronization step has been successfully performed, instead of using the time threshold value to judge whether the speed synchronization step has been successfully performed in the existing gear shift control method. In this way, the gear shift control method of the present application can avoid the problems of erroneous interruption and unexpected acceleration of the vehicle that may be caused by the existing solutions. Further, according to the present application, there is provided a gear shift control device that adopts the above-mentioned gear shift control method and has the same effect.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a schematic topology illustration of a hybrid propulsion system with a P2 architecture; FIG. 2A is a flowchart showing a gear shift control method for a vehicle drive system according to the related art; FIG. 2B is a schematic diagram showing the curves of various parameters that change with time during a shift-down process performed using the prior art shift control method for the hybrid drive system in FIG. 1, wherein the horizontal axis represents time; FIG. 2C is a schematic diagram showing, when a malfunction occurs, the curves of the various parameters that change with time during the shift-down process performed using the prior art gear shift control method for the hybrid drive system in FIG. 1, the malfunction being caused by a synchronizer not being disengaged from a gear before the shifting, and the horizontal axis representing time; FIG. 3A is a flowchart showing a gear shift control method for a vehicle drive system according to an embodiment of the present application; FIG. 3B is a schematic diagram showing, when a malfunction occurs, the curves of the various parameters that change with time during the shift-down process performed using the gear shift control method according to an embodiment of the present application for the hybrid drive system in FIG. 1, the malfunction being caused by a synchronizer not being disengaged from a gear before the shifting, and the horizontal axis representing time; and FIG. 4 is a structural block diagram showing a gear shift control device according to an embodiment of the present application.Explanation of CharactersICE: Engine; EM: Electric motor; C: Clutch; T: Transmission; A: Synchronizer; G11, G12, G21, G22: Gears;HCU: hybrid control unit; MCU: engine control unit; GCU: transmission control unit; SCU: gear shift control unit; COM: computer-on module; JM: judgment module; MU: modification unit.CONCRETE EMBODIMENTSExemplary embodiments of the present application will be described below with reference to the drawings. It should be understood that this specific description is intended to teach those skilled in the art how to practice the present application, and is not intended to exhaustively disclose all possible implementations of the present application, nor to limit the scope of the present application.In the present application, "connected in a gear-like manner" means that two components may be connected to each other by transmitting torque. Unless otherwise stated, this includes a direct or indirect connection between the two components. "Always connected in a gear-like manner" means that the two components are always connected in the gear-like manner, and "connected in a controllable gear-like manner" means that the two components may be connected or disconnected in a gear-like manner.In the present application, "rotation speed" may refer to, for example, the number of revolutions per unit time of an object rotating about a central axis, the unit for which may be, for example, U / min (revolutions per minute); "speed" may refer to, for example, a ratio of the distance of a moving object to time, the unit for which may be, for example, m / s, km / h, etc.In the present application, an outer sleeve of a synchronizer is driven for operation by a fork. When the outer sleeve is engaged with a corresponding gear by the drive of the fork, the synchronizer is in an engaged state. When the outer sleeve is not engaged with a gear by the drive of the fork, the synchronizer is in a neutral state.A gear shift control method for a vehicle drive system according to an embodiment of the present application will be described below with reference to the drawings.Generally speaking, and as shown in FIG. 3A, the gear 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 with respect to the hybrid drive system of the vehicle in FIG. 1, and with respect to the shift-down process as an example performed by the transmission T from the first gear pair consisting of the gears G 11 and G 12 to the second gear pair consisting of the gears G 21 and G 22, the shift control method according to the present application will be described in detail in conjunction with FIGS. 3A and 3B.When the gear shift control method shown in FIG. 3A is used to start the gear shift process, the first torque control step is first executed, and the gear shift process enters phase S 1 as shown in FIG. 3B. In phase S 1, the hybrid control unit HCU of the vehicle sends a torque request to the engine control unit MCU of the vehicle, and the engine control unit MCU controls the torque of the electric motor EM so that the torque of the electric motor EM gradually decreases and reaches 0 at the end of phase S 1. In phase S 1, the actual rotational speed of the electric motor EM remains consistent with the target rotational speed, and the vehicle speed slightly increases. Moreover, at the beginning of phase S1, the hybrid control unit HCU has already set the target gear of the synchronizer A to G21 from gear G11, but the hybrid control unit HCU has not sent a signal to the transmission control unit GCU to control the fork movement. Therefore, the target fork position, the monitored fork position signal, and the actual fork position all indicate that the synchronizer A is in an engaged state with the gear G 11.Further, after the engine control unit MCU has given feedback to the hybrid control unit HCU that the actual torque of the electric motor EM is 0, the disengagement step is executed, and the gear shift process occurs in phase S 2 shown in FIG. 3B. In phase S 2, the torque of the electric motor EM remains at 0, the actual rotational speed of the electric motor EM remains consistent with the setpoint rotational speed, and the vehicle speed remains approximately unchanged. Moreover, at the beginning of phase S 2, the hybrid control unit HCU transmits the target fork position to the transmission control unit GCU of the vehicle, 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 G 11. Therefore, at the end of phase S 2, when all components successfully execute the above-mentioned process, both the monitored fork position signal and the actual fork position indicate that the synchronizer A is in the neutral state in which the synchronizer A is not engaged with any gear. However, to illustrate the error correction mechanism of the gear shift control method of the present application during the speed synchronization step, FIG. 3B shows that the synchronizer A is not actually successfully disengaged from gear G 11, but the monitored fork position signal erroneously represents that the synchronizer A has been disengaged from gear G 11.Further, after the transmission control unit GCU has given feedback to the hybrid control unit HCU that the synchronizer A is in the neutral state, the rotation speed synchronizing step is executed, and the gear shifting process occurs in phase S 3 shown in FIG. 3B. In phase S 3, the hybrid control unit HCU sends a speed request to the engine control unit MCU of the vehicle, and the engine control unit MCU controls the torque of the electric motor EM. By changing the torque of the electric motor EM, the rotational speed of the electric motor EM can be increased. In phase S 3, the target rotational speed of the electric motor EM may be calculated by using the rotational speed of the output shaft of the transmission T via the gear ratio of the second gear pair, or may be obtained by directly monitoring the rotational speed of the gear G 21 used as the target gear in the second gear pair. The actual rotational speed of the electric motor EM is smaller than the target rotational speed of the electric motor EM, and by setting a curve corresponding to the control rotational speed, the actual rotational speed gradually approaches the target rotational speed. Since FIG. 3B shows a situation where a malfunction occurs during execution of the gear shift control process, i.e., although the transmission control unit GCU gives feedback to the hybrid control unit HCU that the synchronizer A is in the neutral state at the beginning of phase S 3, the actual fork position indicates that the synchronizer A has not actually completed disengagement from the gear G 11 and the synchronizer A is still in an engagement state with the gear G 11. In this way, after controlling the torque of the electric motor EM to accelerate the electric motor EM, the actual rotational speed of the motor EM cannot be controlled to be consistent with the target rotational speed.To deal with this situation, in the gear shift control method of the present application, as shown in FIG. 3A, after starting the speed synchronizing step, the expected speed difference is calculated using the torque of the electric motor EM, the drag torque of the input shaft S, and the rotational inertia of the electric motor EM and the input shaft S, and the speed reference value is calculated using the vehicle speed, the gear ratio of the first gear pair, and the gear ratio of the second gear pair. If the rotational speed difference to be expected is greater than the rotational speed reference value before the actual rotational speed of the electric motor EM is consistent with the setpoint rotational speed, the rotational speed synchronization step is interrupted.Specifically, it is assumed that the torque of the electric motor EM is T M( for example, with a unit N·m), the drag torque of the input shaft S is T f( for example, with a unit N·m), both the rotational inertia of the electric motor EM and that of the input shaft S are J (for example, with a unit kg·m 2) and the offset rotational speed N is O where the offset rotational speed is an arbitrary value between -100 U / min and -300 U / min. Then, in the speed synchronization step, after a time t (e.g., with a unit s) has elapsed since the exact moment when the transmission T fed back the signal indicating that the synchronizer A has shifted to the neutral state, the expected speed difference N(t) (e.g., with a unit U / min) is expressed as:In the above-mentioned formula, a conversion coefficient is for a conversion process for rotational speed units. Since the unit of N(t) is U / min (revolutions per minute) and the unit of the result obtained by integrating the torque is rad / s (radians per second), the above-mentioned conversion coefficient for the conversion must be set.Assume that the vehicle speed is v (e.g., at a unit km / h), the gear ratio of the first gear pair is r 1, the gear ratio of the second gear pair is r 2, the wheel radius is R (e.g., at a unit m), and the offset value is f (V), the offset value being any value between 0.95 and 1.05. Then, the reference value N(th) (at, for example, a unit U / min) is expressed as: wherein the vehicle speed v may be a speed of the vehicle at just the moment the transmission T feeds back the signal indicating that the synchronizer A has switched to the neutral state, so that the reference value N(th) is actually a fixed value. Alternatively, the vehicle speed v may be a current speed of the vehicle after a time t has elapsed since the exact moment when the transmission T fed back the signal indicating that the synchronizer A has shifted to the neutral state so that the reference value N(th) is actually a variable. Moreover, the gear ratio of the first gear pair is the total gear ratio of the torque transmission path corresponding to the first gear pair in the entire transmission system, and the gear ratio of the second gear pair is the total gear ratio of the torque transmission path corresponding to the second gear pair in the entire transmission system.In the above-mentioned formula, the conversion coefficient is for the conversion process for rotational speed units. Since the unit of the vehicle speed is v km / h and the unit of the reference value N(th) is U / min, the above-mentioned conversion coefficient for the conversion must be set.The gear shift control method according to an embodiment of the present application also includes a correction step. Once the speed synchronizing step is interrupted according to the above-mentioned logical judgment, the correcting step is executed, and the gear shifting process enters in phase S 6, as shown in FIG. 3B. At the beginning of phase S 6, the hybrid control unit HCU changes the target gear. In phase S 6, the torque of the electric motor EM is reduced to a predefined value (the predefined value may optionally be 0) and the setpoint fork position signal is adapted as a function of the setpoint gearwheel. In this way, unexpected accelerations of the vehicle can be avoided.Further, when the speed synchronization step has been successfully executed so that the actual speed of the electric motor EM is consistent with the target speed, as shown in FIG. 3A, the engagement step and the second torque control step are sequentially executed. In the engagement step, the synchronization device A is engaged with the setpoint gear, for which purpose reference can be made specifically to phase S 4 in FIG. 2B. In the second torque control step, the torque of the electric motor EM is controlled to increase, for which reference may be made specifically to phase S 5 in FIG. 2B, and the torque of the electric motor EM may be transmitted to the wheels via the second gear pair. In this way, the entire downshift process from the first gear pair to the second gear pair is completed using the above-mentioned gear shift control method.The technical solutions of the present application have been described in detail in the above-mentioned concrete embodiments, the following being a supplementary explanation. i. It is understood that by using the logical judgment based on the expected rotational speed difference and the rotational speed reference value, the gear shift control method of the present application can not only avoid the problem of unexpected acceleration of the vehicle caused by excessive torque of the electric motor EM as described in the above-mentioned embodiment, but also avoid the problem of erroneous interruption of the gear shift process caused by too low torque of the electric motor EM. ii. It is understood that, before the gear shift control method of the present application is used by the hybrid drive system shown in FIG. 1 to perform the gear shift process, the clutch C can be in a disengaged state, such that the engine ICE is separated from the input shaft S of the transmission T. iii. It is understood that the vehicle drive system to which the gear shift control method of the present application can be applied is not limited to the hybrid drive system having the P2 architecture shown in FIG. 1, but can be applied to other drive systems. For example, it may be applied to a bridge drive system in which the internal combustion engine is omitted and the engine is always connected in a transmission-like manner to the input shaft of the transmission. iv. In the above-mentioned concrete embodiments, the shift-down process using the gear shift control method of the present application is described. It is understood that in the case of performing an upshift process using the gear shift control method of the present application, the speed synchronization step is interrupted when the absolute value of the expected speed difference is larger than the absolute value of the reference value before the actual speed is consistent with the target speed. v. In a gear shift control method according to an embodiment of the present application, the offset speed is a parameter used for correcting a final value of the expected speed difference, and a criterion for setting a value of the offset speed may be determined according to relevant requirements for safe operation. The offset value may be an empirical parameter, wherein a criterion for defining the offset value may be ascertained as a function of the vehicle speed. The higher the vehicle speed, the larger the offset value. In an optional solution to the gear shift control method of the present application, the offset rotation speed and the offset value may be removed, and accordingly, the expected rotation speed difference and the rotation speed reference value are calculated using the following expressions.Moreover, in the present application, the value of π may be 3.14 or may be more accurately set to increase the accuracy.The present application also provides a gear shift control device to which the gear shift control method according to an embodiment of the present application is applied or in which the gear shift control method according to an embodiment of the present application is implemented. The gear shift control device may include a speed synchronization unit and a modification unit independent of other control units of the vehicle, or may include a speed synchronization unit and a modification unit integrated with other control units of the vehicle.In a case where the speed synchronization unit and the modification unit are independent of other control units, as shown in FIG. 4, the gear shift control device may include the hybrid control unit HCU, the transmission control unit GCU, the motor control unit MCU, the speed synchronization unit SCU, and the modification unit MU, which are electrically connected and may communicate with each other by signaling.The transmission control unit GCU may monitor a state of the synchronizer of the transmission and provide the state of the synchronizer as feedback. The motor control unit MCU may monitor the torque and the rotational speed of the motor and provide the torque and the rotational speed of the motor as feedback, and may also control the torque of the electric motor EM to adjust the rotational speed of the electric motor EM. The hybrid control unit HCU is electrically connected to the transmission control unit GCU and the motor control unit MCU, the hybrid control unit HCU may receive a state signal of the synchronizer provided by the transmission control unit GCU as feedback, and may transmit a signal to the transmission control unit GCU to change the state of the synchronizer. The hybrid control unit HCU may receive the torque and the rotational speed of the motor provided by the motor control unit MCU as feedback, and may transmit a signal to the motor control unit MCU to control the torque of the motor to adjust the rotational speed of the motor. The hybrid control unit HCU, the transmission control unit GCU, and the engine control unit MCU may adopt the respective existing control units of the vehicle.During execution of the gear shift control method of the present application, the speed synchronization unit SCU may receive the required parameters transmitted by the hybrid control unit HCU to calculate the expected speed difference and the speed reference value, and may generate an interrupt signal to interrupt the speed synchronization step when it is determined that the absolute value of the expected speed difference is larger than the absolute value of the speed reference value. More specifically, the speed synchronization unit SCU may include a computer-on module COM configured to calculate the expected speed difference and the speed reference value of the motor, and a judgment module JM configured to judge a relationship between the absolute value of the expected speed difference and the absolute value of the speed reference value. The computer-on module COM and the evaluation module JM are electrically connected so that signals can be transmitted between the computer-on module COM and the evaluation module JM. It is understood that during the calculation of the expected rotational speed difference and the rotational speed reference value by the computer-on module COM, the above-described parameters and calculation methods can be used for the calculation. For example, the computer-on module uses the torque of the engine, the drag torque of the input shaft, and the rotational inertia of the engine and that of the input shaft to calculate a result as the expected speed difference of the engine. In addition, the computer-on module COM uses the sum of the result and the offset rotational speed as the expected rotational speed difference, wherein the offset rotational speed is an arbitrary value between -100 U / min and -300 U / min. Moreover, during the gear shifting process from the first gear pair to the second gear pair, the computer-on module COM uses the vehicle speed, the gear ratio of the first gear pair, and the gear ratio of the second gear pair to calculate a result value as a rotation speed reference value. Furthermore, the computer-on module COM uses the product of the offset value and the result value as a rotational speed reference value, wherein the offset value is an arbitrary value between 0.95 and 1.05. Accordingly, when the judgment module JM judges that the absolute value of the expected rotational speed difference is larger than the absolute value of the rotational speed reference value, the judgment module JM generates an interrupt signal to interrupt a process in which the actual rotational speed of the motor gradually approaches the target rotational speed of the motor.During execution of the gear shift control method of the present application, after the interrupt signal is sent to the hybrid control unit HCU, the hybrid control unit HCU may control the torque of the electric motor EM via the motor control unit MCU to interrupt the speed synchronization step. Subsequently, the modification unit MU generates a predetermined torque that the electric motor EM needs to reach after the interruption, and the modification unit MU controls the torque of the electric motor EM or controls the torque of the electric motor EM via the motor control unit MCU to reach the predetermined torque. In an optional solution, the predetermined torque may be 0.Moreover, in the case that the speed synchronization unit and the modification unit are integrated into other control units, in an optional solution, the functions realized by the speed synchronization unit and the modification unit may be integrated into the hybrid control unit.
Claims
A gear shift control method for a vehicle drive system, the vehicle drive system comprising an electric motor (EM) and a transmission (T), and the electric motor (EM) is always connected in a transmission-like manner to an input shaft (S) of the transmission (T), the gear 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) motor gradually approaches the target speed; and before the actual speed is consistent with the target speed, obtaining the expected speed difference and the speed reference value of the motor; and in the case that the absolute value of the expected speed difference is larger than the absolute value of the speed reference value, interrupting the speed synchronization step.The gear shift control method according to claim 1, wherein the torque of the electric motor (EM), the drag torque of the input shaft (S), and the rotational inertia of the electric motor (EM), and the rotational inertia of the input shaft (S) are used to calculate the result value as the expected rotational speed difference of the electric motor (EM).The gear shift control method according to claim 2, wherein the offset rotational speed is set to an arbitrary value between -100 U / min and -300 U / min, and the sum of the result value and the offset rotational speed is used as the expected rotational speed difference.The gear shift control method according to claim 1, wherein the gear shift process is a gear shift process from the first gear pair (G11, G12) to the second gear pair (G21, G22), and the vehicle speed, the gear ratio of the first gear pair (G11, G12), and the gear ratio of the second gear pair (G21, G22) are used to calculate the result value as a rotation speed reference value.The gear shift control method according to claim 4, wherein the offset value is set to an arbitrary value between 0.95 and 1.05, and the product of the offset value and the result value is used as the rotation speed reference value.The gear shift control method according to claim 4 or 5, wherein the vehicle speed is the speed of the vehicle at just the moment when the transmission (T) provides, as feedback, a signal indicating that a synchronizer (A) has shifted to a neutral state; or the vehicle speed is a current speed of the vehicle after elapse of a predetermined time from the exact moment when the transmission (T) provides, as feedback, a signal indicating that the synchronizer (A) has shifted to the neutral state.The gear shift control method according to claim 6, wherein when the vehicle speed is the current speed, the expected rotational speed difference and the rotational speed reference value of the engine are obtained in real time after the transmission (T) provides, as feedback, the signal indicating that the synchronizer (A) has shifted to the neutral state.The gear shift control method according to any one of claims 1 to 7, wherein after the stopping of the speed synchronizing step, the gear shift control method further comprises a correction step of reducing the torque of the electric motor (EM) to a predetermined value.A gear shift control device to which the gear shift control method according to any one of claims 1 to 8 is applied.The gear shift control device according to claim 9, comprising: a speed synchronization unit (SCU) configured to obtain the expected speed difference of the electric motor (EM) and the speed reference value during a process in which the actual speed of the electric motor (EM) gradually approaches the target speed of the electric motor (EM), and judge the relationship between the absolute value of the expected speed difference and the absolute value of the speed reference value.The gear shift control device according to claim 10, wherein the speed synchronization unit (SCU) comprises: a computer-on module (COM) configured to calculate the expected speed difference of the engine and the speed reference value; and a judging module (JM) configured to judge the relationship between the absolute value of the expected speed difference and the absolute value of the speed reference value, wherein the computer-on module (COM) and the judging module (JM) are electrically connected, thereby enabling transmission of signals between the computer-on module (COM) and the judging module (JM).The gear shift control device according to claim 11, wherein when the judging module (JM) judges that the absolute value of the expected rotational speed difference is larger than the absolute value of the rotational speed reference value, the judging module (JM) generates an interrupt signal to interrupt the process in which the actual rotational speed of the electric motor (EM) gradually approaches the target rotational speed of the electric motor (EM).The gear shift control device according to any one of claims 10 to 12, wherein the gear shift control device further comprises a modification unit (MU) configured to reduce the torque of the electric motor (EM) to a predetermined value after the process in which the actual rotational speed of the electric motor (EM) gradually approaches the target rotational speed of the electric motor (EM) is interrupted.