Technical Field

The present disclosure relates to the technical field of vehicle gearing control, in particular, to a gearing control unit and a gearing control method for a vehicle power system, to a vehicle power system comprising the gearing control unit, and to a respective machine-readable storage medium.

Background

An automated transmission is an automotive transmission that can automatically change the gear drive ratio during a vehicle drive. An automatic transmission is typically a plurality of gears that drives the gearbox through a motor to achieve upshift or downshift. In the gear system, the design of the back lash) is essential because it facilitates the lubrication between contacting profiles and avoids excessive friction during gear engagement.

During the gear shift, if the motor torque transitions too quickly, a large shock vibration and knock noise will be produced when changing from one side to the other, which is undesirable. On the other hand, reducing the motor’s torque change slope to control the impact of the gap switching increases the gearing duration, which means that the energy interruption time is longer, which is not expected. In the prior art, it is generally difficult to balance maintaining the smoothness of the back lash in the gearing process with reducing the gearing duration. It is generally the case that one of them shall be comprised.

Summary

In this context, the present disclosure is intended to provide a gearing control method that allows for a reduction in the gearing duration while maintaining a smoothness of the back lash during gearing without requiring vehicle- related hardware changes.

According to one aspect of the present disclosure, a gearing control unit for a vehicle power system is provided, the gearing control unit comprising a motor, a plurality of gears for outputting power to the motor at a plurality of gears, and a coupler for coupling a respective gear to a motor drive shaft, wherein the gearing control unit is configured to: control the gear coupled to the motor drive shaft under the current gear and decouple the coupler; adjust the motor speed to cause the motor’s actual speed to be less than zero torque by the first predetermined torque adjustment amount or equal to zero torque; adjust the motor speed to make the difference between the motor’s actual speed and the motor’s reference speed calculated based on the gearing request to be the first predetermined speed adjustment amount; When the difference between the motor’s actual speed and the motor’s reference speed is less than or equal to the speed difference threshold, the speed control or torque control is performed on the motor, and the coupler is controlled to couple the gear corresponding to the target gear and the motor drive shaft; When the gear corresponding to the target gear is coupled with the motor drive shaft, the speed control or torque control is completed.

According to another aspect of the present disclosure, a vehicle power system is provided, comprising: a motor; a plurality of gears for outputting the motor power at a plurality of gears; a coupler for coupling a respective gear to a motor drive shaft to achieve a different gear; and a gearing control unit for controlling the motor speed and/or motor torque as described above to control the gearing process.

According to yet another aspect of the present disclosure, a gearing control method for a vehicle power system is provided, the gearing control method comprising a motor, a plurality of gears for outputting power to the motor at a plurality of gears, and a coupler for coupling a respective gear to a motor drive shaft, wherein the gearing control method comprises: controlling the gear coupled with the motor drive shaft under the current gear and decoupling the coupler; adjusting the motor speed to make the motor’s actual speed to be lower than zero torque by the first predetermined torque adjustment amount or higher than zero torque by the first predetermined torque adjustment amount; adjusting the motor speed to make the difference between the motor’s actual speed and the motor’s reference speed calculated based on the gearing request to be the first predetermined speed adjustment amount; When the difference between the motor’s actual speed and the motor’s reference speed is less than or equal to the speed difference threshold, the speed control or torque control is performed on the motor, and the coupler is controlled to couple the gear corresponding to the target gear and the motor drive shaft; When the gear corresponding to the target gear is coupled with the motor drive shaft, the speed control or torque control is completed.

According to yet another aspect of the present disclosure, a machine- readable storage medium is provided, the machine-readable storage medium having stored executable instructions that, when executed, cause one or more processors to perform the gearing control method as described above.

Brief Description of the Drawings

The technical solutions of the present disclosure are clearer from the following detailed description with reference to the accompanying drawings. It may be understood that these accompanying drawings are merely used for illustration purposes, but are not intended to limit the protection scope of the present disclosure.

Fig. 1 is a schematic block diagram of a vehicle power system according to the examples of the present disclosure.

Fig. 2A schematically illustrates one possible embodiment of the vehicle power system of Fig. 1.

Fig. 2B schematically illustrates the back lash switching of the gear system of Fig. 2A during a gearing process.

Fig. 3 shows a flow chart of a gearing control unit performing a gearing control process, according to the examples of the present disclosure.

Fig. 4 schematically illustrates a upshift control process in a drive state of the vehicle, according to the examples of the present disclosure.

Fig. 5 schematically illustrates a downshift control process in a drive state of the vehicle, according to the examples of the present disclosure.

Fig. 6 schematically illustrates a upshift control process in an energy recovery state of the vehicle, according to the examples of the present disclosure.

Fig. 7 schematically illustrates a downshift control process in an energy recovery state of the vehicle, according to the examples of the present disclosure. Fig. 8 is a flow chart of a gearing control method for a vehicle power system, according to the examples of the present disclosure.

Description of Embodiments

The examples of the present disclosure relate to the technical solution of gearing control, which is applicable to the upshift and downshift control of the vehicle in the drive state, and also applicable to the upshift and downshift control of the vehicle in the energy recovery state.

The following describes specific implementations of the present disclosure with reference to the accompanying drawings.

Fig. 1 schematically illustrates a vehicle power system 100 according to the examples of the present disclosure, comprising: A motor 10, a gear unit 20, a gearing control unit 30, and a coupler 40.

The motor 10 provides a drive force for the gear unit 20. The motor 10 may comprise a motor drive shaft for driving the gear unit 20. The gear unit 20 comprises a plurality of gears and may output power of the motor 10 at a plurality of gears. The coupler 40 is used to couple a respective gear with a motor drive shaft to achieve a different gear. The coupler 40 may be implemented to comprise a dog clutch (DC: ), or can also be implemented as a synchronizer. The gearing control unit 30 comprises a gearing control method for controlling the motor 10 and the coupler 40 to control shifting between different gears, according to the examples of the present disclosure. The gearing control unit 30 may be implemented by using hardware, software, or a combination of software and hardware. Parts implemented by hardware may be implemented in one or more application-specific integrated circuits (ASIC), digital signal processors (DSP), programmable logic devices (PLD), field programmable gate arrays (FPGA), processors, controllers, microcontrollers, microprocessors, electronic units designed to perform functions thereof, or combinations thereof. Parts implemented by software may be implemented by using microcode, program code, or a code segment, or may be stored in a machine-readable storage medium such as a storage component.

In an example of the present disclosure, the gearing control unit 30 is implemented to include a memory and a processor. The memory includes instructions, and when the instructions are executed by the processor, the processor performs the gearing control method according to this example of the present disclosure.

In an example of the present disclosure, the gearing control unit 30 is implemented as software and is disposed in a controller of a vehicle power system.

Fig. 2A illustrates one example of the vehicle power system 100 of Fig. 1. Referring to Fig. 2, the gear unit 20 comprises a plurality of gears a-f. The coupler 40 comprises a first dog clutch 41 (DC1 41), a second dog clutch (DC2 42), and an actuator 43 (DCA 43). The gearing control unit 30 may control the first and second dog clutches by controlling the actuator 43 to couple or decouple the respective gears from the motor drive shaft.

The example in Fig. 2A can achieve 4 gears, i.e., gear 1 , gear 2, gear 3 and gear 4, by the settings in Table 1 below.

Table 1

Fig. 2B schematically illustrates the back lash switching of the gear system of Fig. 2A during a gearing process. Referring to Fig. 2B, at the 1st gear, gear a drives gear e, and gear f drives gear b for idling. Next, after the gear shift, gear e drives gear a for idling under the inertia action, while gear f drives gear b for idling under the inertia action. Next, after being shifted to gear 2, gear b drives gear f, and gear e drives gear a. During this process, the back lash has changed.

In such a back lash switching process, if the motor torque changes greatly in a relatively short period of time, it causes vibration and noise, which is also detrimental to gear life. In this regard, the existing solution is to limit motor torque change slopes to a smaller value, but such solution in turn raises the issue of increased gearing duration. A gearing control method according to the examples of the present disclosure can solve this issue.

The gearing control method according to the examples of the present disclosure allows the motor to be torqued earlier (i.e., from positive to negative torque and/or from negative to positive torque) by controlling motor torque and/or motor speed, thereby enabling the back lash switching to be advanced, so that the impact caused by the back lash switching is minor and the torque change slope is not controlled at a smaller value, thus reducing the gearing duration while avoiding the larger impact of the back lash.

It can be understood that Figs. 2A and 2B are for illustrative purposes only, and that the present gearing control method is not limited to this particular architecture. When the gear system is implemented as a style other than that of Fig. 2A, the back lash switching during the gearing process is similar, as is the gearing control method consistent with examples of the present disclosure.

Fig. 3 shows a gearing control process 300 performed by a gearing control unit 30 according to the examples of the present disclosure.

Referring to Fig. 3, in block 302, the gearing control unit 30 receives a gearing request, such as a upshift request or a downshift request. The uplift request may include a upshift request in the drive state of the vehicle and a upshift request in the energy recovery state of the vehicle. The downshift request may include a downshift request in the drive state of the vehicle and a downshift request in the energy recovery state of the vehicle.

The gearing request may be triggered, for example, by a vehicle driver or by a control system of the vehicle. The present disclosure does not define how to trigger this gearing request.

In block 304, in response to the gearing request, the gearing control unit 30 unloads the motor torque, i.e., controlling the motor torque to be lower or higher than zero torque by the first predetermined torque adjustment amount. Notably, the existing gearing control method is to zero the motor torque upon receipt of the gearing request, i.e., to zero. The gearing control method according to examples of the present disclosure is to change the motor torque to a value that is slightly higher or lower than zero torque, i.e., a smaller negative torque or a smaller positive torque.

The first predetermined torque adjustment amount is associated with the following parameters: An equivalent rotational inertia of a rotating component in fixed connection with a motor, a friction torque of the rotating component, and a maximum allowable value of Ndiffmax of speed difference across the coupler. The rotating components in fixed connection with the motor refer to those rotating components that are not decoupled by gearing.

In an example of the present disclosure, the first predetermined torque adjustment amount is determined by the formula (1):

T1 = J1*p + Tf (1) wherein T1 is the first predetermined torque adjustment amount;

J1 is an equivalent rotational inertia of a rotating component in fixed connection with a motor during the decoupling of the gear corresponding to the current gear from the motor drive shaft;

P is the set value of the motor’s angle acceleration;

Tf is the friction torque of the rotating component.

In this example, the set value of the motor’s angle acceleration is associated with the maximum allowable value Ndiffmax of the speed difference across the coupler. The greater the maximum allowable value is, the greater the set value of the motor’s angle acceleration will be. For example, if the maximum allowable value of the speed difference is 50 rpm, it is recommended to set the change in motor speed to no more than 10 rpm, so during the 200ms of gear coupling, the value of p is: 10 rpm/0.2s = 10*2*pi/60/0.2 = 5.23 rad/s ^A 2. In this example, the friction torque Tf is associated with the linear speed of the rolling bearing of the rotating component, the viscosity of the lubricating oil or grease, and the ambient temperature. For example, the friction torque Tf is proportional to the linear speed of the rolling bearing of the rotating component, proportional to the viscosity of the lubricating oil or grease, and inversely to the ambient temperature.

In block 306, the gearing control unit 30 controls the coupler to decouple the gear coupled to the motor drive shaft under the current gear (Disengage). For example, the gearing control unit 30 sends instructions to the DCA for decoupling. The DCA then manipulates the dog clutch to perform the decoupling operation.

In block 308, the gearing control unit 30 adjusts the motor speed such that the difference between the motor’s actual speed and the motor’s reference speed calculated based on the gearing request is the first predetermined speed adjustment amount. For example, the gearing control unit 30 sends a request for a motor speed to a MCU of a motor, the motor speed requested being higher or lower than the motor’s reference speed by the first predetermined speed adjustment amount.

It should be understood that the motor’s reference speed may be varied throughout the gearing process, e.g., the motor’s reference speed may be expressed as a plurality of segments of broken lines and/or curves over time. The motor’s reference speed may be calculated based on the vehicle speed, for example, to calculate how much the motor speed is to reach to match the vehicle speed corresponding to a target gear (e.g., a upshift gear or a downshift gear). The present disclosure does not define how the motor’s reference speed is calculated.

The first predetermined speed adjustment amount correlates to the maximum allowable value Ndiffmax of the speed difference across the coupler. In an example of the present disclosure, the first predetermined speed adjustment ranges from: 1/3 to 1/2 of the maximum allowable value Ndiffmax.

In block 310, the gearing control unit 30 performs speed control or torque control on the motor when the difference between the motor’s actual speed and the motor’s reference speed is less than or equal to the speed difference threshold. Moreover, the gearing control unit 30 controls the coupler to drive the gear corresponding to the target gear (e.g., the gear of the upshift gear or the gear of the downshift gear) is coupled to the motor drive shaft. For example, the gearing control unit 30 sends instructions to the DCA coupled to the target gear. The DCA then manipulates the dog clutch to perform coupling operation to the target gear.

The situation where the difference between the motor’s actual speed and the motor’s reference speed is less than the speed difference threshold may be understood as the motor entering a predetermined control window. The speed difference threshold is predetermined, e.g., based on the abovedescribed maximum allowable value of the speed difference across the coupler. The speed difference threshold may be pre-set to be equal to or slightly less than the maximum allowable value.

In an example of the present disclosure, referring to block 3101 , the gearing control unit 30 sends an instruction to the motor controller to enter the speed control mode, and the motor controller performs speed control on the motor. This speed control includes: The motor speed is controlled such that the difference between the motor’s actual speed and the motor’s reference speed is the second predetermined rotational speed adjustment amount, i.e., the motor’s actual speed is lower or higher than the motor’s reference speed. The second predetermined speed adjustment amount may be the same as the first predetermined speed adjustment amount or may be different than the first predetermined speed adjustment amount. Similar to the first predetermined speed adjustment amount, the second predetermined speed adjustment amount correlates with the maximum allowable value Ndiffmax of the speed difference across the coupler. In an example of the present disclosure, the values for the second predetermined speed adjustment amount range from: 1/3 to 1/2 of the maximum allowable value Ndiffmax.

In another example of the present disclosure, referring to block 3102, the gearing control unit 30 sends an instruction to the motor controller to enter the torque control mode, and the motor controller then performs torque control on the motor. The torque control includes: The motor torque is controlled such that the difference between the motor’s actual torque and the motor’s reference torque calculated based on the gearing request is the second predetermined torque adjustment amount, i.e., the motor’s actual torque is higher or lower than the motor’s reference torque by the second predetermined torque adjustment amount.

It should be understood that the motor’s reference torque may vary throughout the gearing process, e.g., the motor’s reference torque may be expressed as a plurality of broken lines and/or curves over time. The motor’s reference torque may be calculated based on the vehicle speed, for example, to calculate how much the motor torque is going to reach to match the vehicle speed corresponding to a target gear (e.g., a upshift gear or a downshift gear). The present disclosure does not define how the motor’s reference torque is calculated.

The second predetermined torque adjustment amount may be the same as the first predetermined torque adjustment amount or may be different than the first predetermined torque adjustment amount. Similar to the first predetermined torque adjustment amount, the second predetermined torque adjustment amount is associated with the following parameters: An equivalent rotational inertia of a rotating component in fixed connection with a motor, a friction torque of the rotating component, and a maximum allowable value Ndiffmax of the speed difference across the coupler.

Notably, in calculating the equivalent rotational inertial, the second predetermined torque adjustment amount is equivalent rotational inertial in the gear coupling process employed by the inertial J2, while the first predetermined torque adjustment amount is equivalent rotational inertial J1 is gear decoupling inertial.

In an example of the present disclosure, the maximum allowable value Ndiffmax of the speed difference across the coupler is calculated by the following equation (2):

T2 = J2*p + Tf (2) wherein T2 is the second predetermined torque adjustment amount;

J2 is the equivalent rotational inertial of the rotating component in fixed connection with the motor during the coupling of the gear according to the target gear with the motor drive shaft;

P is the set value of the motor’s angle acceleration;

Tf is the friction torque of the rotating component.

Similar to the calculation of the first predetermined torque adjustment amount, in this example, the set value of the motor’s angle acceleration is associated with the maximum allowable value NdiffmaxOf the speed difference across the coupler. The greater the maximum allowable value of this speed difference is, the greater the set value of the motor’s angle acceleration may be.

“Speed difference across the coupler” may be understood as the speed difference across between any two of the plurality of components of the coupler. For example, the speed difference may be: The speed difference D1 between the motor speed and the gear to be coupled; or the speed difference D2 between the motor’s gear group transmission speed and the gear to be coupled; or the speed difference D3 between the speed of other torque source and the gear/gear axis to be coupled. Accordingly, “the maximum allowable value Ndiffmax of the speed difference across the coupler” refers to the maximum allowable value of these differences. For example, if the maximum allowable value of the speed difference D1 > the maximum allowable value of the speed difference D2 > the maximum allowable value of the speed difference D3, the maximum allowable value of the speed difference Ndiffmax according to examples of the present disclosure is the maximum allowable value of the speed difference D1. Similar to the calculation of the first predetermined torque, in this example, the friction torque Tf is associated with the linear speed of the rolling bearing of the rotating component, the viscosity of the lubricating oil or grease, and the ambient temperature. For example, the friction torque Tf is proportional to the linear speed of the rolling bearing of the rotating component, proportional to the viscosity of the lubricating oil or grease, and inversely to the ambient temperature.

In block 312, the speed control or torque control is ended after the gear corresponding to the target gear is coupled with the motor drive shaft.

In an example of the present disclosure, a stroke sensor is provided on the coupler manipulation actuator for detecting the stroke of a gear operated by the coupler. Upon detection by the stroke sensor of a stroke signal indicating that the gear corresponding to the target gear is being pushed into place by the coupler, the gear corresponding to the target gear is coupled to the motor drive shaft. The gearing control unit 30 ends the speed control or torque control and ends the gearing control in response to the stroke signal.

Figs. 4-7 show examples of a gearing control process in four situations. These four situations include: The vehicle is in the drive state for upshift (hereinafter referred to as “drive upshift”), the vehicle is in the downshift gear (hereinafter referred to as “drive downshift”), the vehicle is in the energy recovery state for upshift (hereinafter referred to as “energy recovery upshift”), and the vehicle is in the energy recovery state for downshift (hereinafter referred to as “energy recovery downshift”). These control processes may be achieved by the above-described gearing control unit 30. For example, the motor functions as a motor in a drive state of the vehicle and as a generator in an energy recovery state of the vehicle.

An example of a gearing control process in each situation is described below with reference to Figs. 4-7.

Fig. 4 shows an example of the drive upshift control process. In Fig. 4, the row “DRIVE_UP” represents a plurality of links driving the upshift control process. The row “BLACK LASH” illustrates the back lash condition corresponding to each of the stages, “b” denotes the back lash, and “FN” denotes the force received when the gear is coupled. “T_Motor” indicates the motor torque. “N_Motor” indicates the motor speed. To clearly show the overadjustment control of the motor speed, the dashed line “N_THEO” indicates the motor’s reference speed and the solid line “N_ACTUAL” indicates the motor’s actual speed (or the requested motor speed). “P_Gear” indicates a gear. In the drive upshift example shown in Fig. 4, the gear rises from gear 1 to gear 2.

Referring to Fig. 4, in block 402, a drive upshift request is received.

In block 404, the control motor torque changes to a lower first predetermined torque adjustment amount (-AT1) than the zero torque, i.e., the motor torque is changed to a negative torque rather than a zero torque as in the existing scheme.

In block 406, the control coupler decouples the gear coupled with the motor drive shaft under the current gear.

In block 408, the motor speed is adjusted such that the motor speed is reduced to be lower than the motor’s reference speed by the first predetermined torque adjustment amount (N_THEO-IZIN1) based on the upshift gear (N_THEO).

In block 410, when the difference between the motor’s actual speed (N_ACTUAL) and the motor’s reference speed (N_THEO) is less than or equal to the speed difference threshold (e.g., 50rpm), speed control is performed on the motor, i.e., controlling the motor speed to be higher than the motor’s reference speed by the second predetermined speed adjustment amount (N_THEO+HD+N2); or alternatively, controlling the motor torque to be higher than the motor’s reference torque by the second predetermined torque adjustment amount (+AT2).

In block 412, when the gear corresponding to the upshift gear is coupled with the motor drive shaft, terminate the speed control or torque control to complete the drive upshift control.

Fig. 5 shows an example of a drive downshift control process. In Fig. 5, the row “DRIVE_DOWN” represents a plurality of links of the drive downshift control process. The row “BLACK LASH” shows the back lash condition corresponding to each link, “b” denotes the back lash, and “FN- denotes the force received when the gear is coupled. “T_Motor” indicates the motor torque. “N_Motor” indicates the motor speed. To clearly show the overadjustment control of the motor speed, the dashed line “V_THEO” represents the motor’s reference speed and the solid line “N_ACTUAL” represents the motor’s actual speed (or the requested motor speed). “P_Gear” indicates a gear. In the drive downshift example shown in Fig. 5, the gear is downshifted from gear 2 to gear 1 .

Referring to Fig. 5, in block 502, a drive downshift request is received.

In block 504, the motor torque is controlled to be higher than zero torque by the first predetermined torque adjustment amount (+AT1), i.e., the motor torque is changed to a positive torque rather than a zero torque as in the existing scheme.

In block 506, the coupler is controlled to disengage the gear coupled to the motor drive shaft under the current gear.

In block 508, the motor speed is adjusted such that the motor speed increases to a speed lower than the motor’s reference speed (N_THEO) by the first predetermined torque adjustment amount (N_THEO-AN1).

In block 510, when the difference between the motor’s actual speed (N_ACTUAL) and the motor’s reference speed (N_THEO) is less than or equal to the speed difference threshold (e.g., 50 rpm), speed control is performed on the motor, i.e., the motor’s actual speed is controlled to be higher than the motor’s reference speed by the second predetermined speed adjustment amount (N_THEO+AN2); or alternatively, the motor torque is controlled to be higher than the motor’s reference torque by the second predetermined torque adjustment amount (+AT2).

In block 512, when the gear corresponding to the downshift gear is coupled with the motor drive shaft, the speed control or the torque control is ended, and the drive downshift control is completed.

Fig. 6 shows an example of an energy recovery upshift control process. In Fig. 6, the row “RECUPERATION_UP” represents a plurality of links in the energy recovery upshift process. Accordingly, “the maximum allowable value Ndiffmax of the speed difference across the coupler” refers to the maximum allowable value of these differences. “T_Motor” indicates the motor torque. “N_Motor” indicates the motor speed. To clearly show the over-adjustment control of the motor speed, the dashed line “N_THEO” indicates the motor’s reference speed and the solid line “N_ACTUAL” indicates the motor’s actual speed (or the requested motor speed). “P_Gear” indicates a gear. In the energy recovery upshift example shown in Fig. 6, the gear rises from gear 1 to gear 2. Referring to Fig. 6, in block 602, an energy recovery upshift request is received.

In block 604, the motor torque s controlled to be lower than zero torque by the first predetermined torque adjustment amount (-AT1), i.e., the motor torque is changed to a negative torque rather than a zero torque as in the existing scheme.

In block 606, the coupler is controlled to disengage the gear coupled to the motor drive shaft under the current gear.

In block 608, the motor speed is adjusted such that the motor speed is reduced to be lower than the motor’s reference speed (N_THEO) calculated based on the downshift request by the first predetermined speed adjustment amount (N_THEO+AN1).

In block 610, when the difference between the motor’s actual speed (N_ACTUAL) and the motor’s reference speed (N_THEO) is less than or equal to the speed difference threshold (e.g., 50rpm), speed control is performed on the motor, i.e., the motor’s actual speed is controlled to be lower than the motor’s reference speed by the second predetermined speed adjustment amount (N_THEO-AN2); or, the motor torque is controlled to be lower than the motor’s reference torque by the second predetermined torque adjustment amount.

In block 612, when the gear corresponding to the upshift gear is coupled with the motor drive shaft, speed control or torque control is ended to complete the energy recovery upshift control.

Fig. 7 shows an example of an energy recovery downshift control process. In Fig. 7, the row “RECUPERATION_DOWN” represents a plurality of links in the energy recovery upshift process. The row “BLACK LASH” illustrates the black lash condition corresponding to each of the stages, “b” denotes the back lash, and “FN” denotes the force received when the gear is coupled. “T_Motor” indicates the motor torque. “N_Motor” indicates the motor speed. To clearly show the over-adjustment control of the motor speed, the dashed line “N_THEO” indicates the motor’s reference speed and the solid line “N_ACTUAL” indicates the motor’s actual speed (or the requested motor speed). “P_Gear” indicates a gear. In the energy recovery downshift example shown in Fig. 6, the gear drops from gear 2 to gear 1.

Referring to Fig. 7, in block 702, an energy recovery downshift request is received.

In block 704, the motor torque is controlled to be higher than zero torque by the first predetermined torque adjustment amount (+AT1), i.e., the motor torque is changed to a positive torque rather than a zero torque as in the existing scheme.

In block 706, the coupler is controlled to disengage the gear coupled to the motor drive shaft under the current gear.

In block 708, the motor speed is adjusted such that the motor speed is reduced to be lower than the motor’s reference speed (N_THEO) by the first predetermined speed adjustment amount (N_THEO+AV1) calculated based on the downshift request.

In block 710, when the difference between the motor’s actual speed (V_ACTUAL) and the motor’s reference speed (N_THEO) is less than or equal to the speed difference threshold (e.g., 50 rpm), speed control is performed on the motor, i.e., the motor’s actual speed is controlled to be lower than the motor’s reference speed by the second predetermined speed adjustment amount (N_THEO-AN2); or, torque control is performed on the motor, i.e., the motor’s actual torque is controlled to be lower than the motor’s reference torque by the second predetermined torque adjustment amount (- AT2).

In block 712, when the gear corresponding to the downshift gear is coupled with the motor drive shaft, the speed control or torque control is ended to complete the energy recovery downshift control.

Referring further to Figs. 4-7, in the process of decoupling the gear from the motor drive shaft under the current gear and the target gear from the motor drive shaft, the motor torque is controlled by controlling the motor speed and/or motor torque to advance over zero, thereby providing a time for the back lash to be replaced and shortening the gearing time.

It should be understood that the values of the first predetermined speed adjustment amount may be different in different situations. For example, in situations where the gear is increased from gear 1 to gear 4 and the gear is increased from gear 1 to gear 2, the values of the first predetermined speed adjustment amount may be different. In the case of drive upshift and energy recovery upshift, the values of the first predetermined speed adjustment amount may be different. Similarly, the values of the second predetermined speed adjustment amount may be different in different situations. Similarly, the values of the first predetermined torque adjustment amount may be different in different situations. Similarly, the values of the second predetermined torque adjustment amount may be different in different situations.

The present disclosure also provides an electric drive bridge for an electric vehicle that includes a gearing control unit 30 as described above. Accordingly, the electric drive bridge also has the features and advantages of the gearing control unit 30 as described above.

Fig. 8 shows a gearing control method 800 according to one example of the present disclosure. The method 800 may be implemented by the abovedescribed gearing control unit 30 or by the above-described vehicle power system 100, so the above-described description of the gearing control unit 30 and vehicle power system 100 is equally applicable here.

Referring to Fig. 8, in step S810, a gearing request is received.

In step S820, in response to the gearing request, the motor torque is unloaded such that the motor torque changes to be lower or higher zero torque by the first predetermined torque adjustment amount.

In step S830, the control coupler disengages the gear coupled to the motor drive shaft under the current gear.

In step S840, the motor speed is adjusted such that the difference between the motor’s actual motor speed and the motor’s reference speed calculated based on the gearing request is the first predetermined speed adjustment amount.

In step S850, when the difference between the motor’s actual speed and the motor’s reference speed is less than or equal to the speed difference threshold, speed control or torque control is performed on the motor and the coupler is controlled to couple a gear corresponding to the target gear to the motor drive shaft.

In step S860, the speed control or torque control is ended when the gear corresponding to the target gear is coupled with the motor drive shaft.

The present disclosure also provides a machine-readable storage medium stored with executable instructions that, when executed, cause the machine to perform the method 800 as described above.

It should be understood that all of the operations in the above-described methods are merely exemplary and that the present disclosure is not limited to any of the operations in the methods or the order of those operations, but rather should encompass all other equivalents under the same or similar ideas.

It should be understood that the gearing control unit may include one or more processors. These processors may be implemented using electronic hardware, computer software, or any combination thereof. Whether these processors are implemented as hardware or software will depend on the particular application and the overall design constraints applied to the system. By way of example, the processors, any portion of the processors, or any combination of processors given herein may be implemented as microprocessors, microcontrollers, digital signal processors (DSP), field programmable gate arrays (FPGA), programmable logic devices (PLD), state machines, gate logic, discrete hardware circuits, and other suitable processing components configured to perform the various functions described herein. The functions of the processor, any portion of the processor, or any combination of processors given herein may be implemented as software executed by a microprocessor, microcontroller, DSP, or other suitable platform.

The software may be broadly considered to represent instructions, instruction sets, codes, code segments, program codes, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, running threads, processes, functions, etc. The software may reside in a computer-readable medium. The computer-readable medium may include, for example, a memory, which may be, for example, a magnetic memory device (e.g., hard disk, floppy disk, magnetic stripe), a CD, a smart card, a flash memory device, random access memory (RAM), read only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), registers, or removable disks. Although the memory is shown as being separate from the processor in the various aspects given herein, the memory may also be located inside the processor (e.g., a cache or register).

The above description is provided for use so that any person skilled in the art may implement various aspects described herein. Various modifications of these aspects are apparent to those skilled in the art, and the general principles defined herein may apply to other aspects. Accordingly, the claims are not intended to be limited to the aspects illustrated herein. Equivalency transforms across all structures and functions of elements described in the various aspects of the present invention known to, or about to be known to, those skilled in the art, will be expressly incorporated herein by reference and is intended to be covered by the claims.