A shift method and system for an electrically driven dog clutch of a transmission

Abstract

The application provides a shift method and system of an electrically-driven dog clutch of a transmission, which comprises the following steps: when receiving a shift instruction issued by an upper computer, the dog clutch is controlled to enter a coupling preparation stage; in the coupling preparation stage, a driving device is controlled to coordinate the rotating speed of a rotating part and simultaneously displace a tooth sleeve, so that the dog clutch enters a preliminary coupling stage; in the preliminary coupling stage, a target torque input to the dog clutch is controlled, so that the dog clutch enters an engagement stage; in the engagement stage, the teeth of the dog clutch are controlled to be aligned, so that the engagement process is completed. The application can greatly improve the shift efficiency of the dog clutch.

Description

Technical Field

[0001] This invention relates to the field of transmission technology, and in particular to a shifting method and system for an electric drive transmission with a dog-tooth clutch. Background Technology

[0002] In the field of vehicle transmission system technology, as new energy electric drive systems continue to evolve towards higher integration, higher transmission efficiency, and lower cost, the dog clutch shifting mechanism, with its core advantages such as simple structure, large torque transmission, long service life, and low manufacturing cost, has become a widely adopted gear shifting solution in electric drive transmissions. Compared with the traditional synchronizer shifting structure, the dog clutch relies on the rigid meshing of the end face teeth to achieve power transmission, which can better adapt to the high-speed, high-torque output characteristics of electric drive systems and has outstanding application value in pure electric and hybrid power transmission systems. However, due to the inherent limitations of its own structural form and meshing principle, the dog clutch needs to rely on the speed matching of the driving end and the driven end during gear engagement, and rigid impact is easily generated at the moment of engagement. Its NVH performance shortcomings have always restricted the further improvement of the overall vehicle shifting quality.

[0003] To improve the shifting shock problem of dog clutches, existing technologies mainly focus on optimization through three technical approaches. The first is a tooth alignment scheme based on active speed regulation of the drive motor combined with an angle sensor. This scheme eliminates the speed difference between the two ends through motor speed regulation and achieves precise tooth slot alignment with the angle signal. However, this scheme has extremely stringent requirements for the accuracy of angle signal acquisition and real-time processing. Sensor errors and signal noise can easily lead to control lag, failing to fundamentally eliminate the instantaneous impact at the tooth tip. The second is a pre-synchronization scheme by adding an auxiliary conical synchronizer. This scheme achieves speed synchronization in advance through a small friction pair before the dog teeth engage. However, this scheme significantly increases the complexity of the mechanical structure and the axial arrangement dimensions, violating the original design intention of simplifying the transmission structure using a dog clutch. The third is a scheme that optimizes the tooth profile of the dog teeth. This involves designing a guiding slope at the tooth tip or using an inverted conical tooth profile to achieve mechanical guidance for tooth entry. However, under conditions of large speed differences, the forced engagement method generates significant impact stress on the tooth surface, leading to sharp meshing noise.

[0004] In summary, none of the existing improvement solutions can completely eliminate shift shock and vibration problems at the meshing principle level. Even with active speed control strategies, due to objective limitations such as sensor accuracy, control cycle, actuator response delay, and tooth backlash, it is still difficult to achieve absolute zero speed difference and zero angle difference at the moment of meshing. Even slight fluctuations in speed and positional deviations can trigger rigid collisions and generate significant instantaneous impact torque. This impact is transmitted step by step along the transmission chain, transforming into broadband vibration and structural noise from the drive axle to the vehicle body. Especially when the vehicle is stationary or crawling at low speeds, repeated meshing noises significantly reduce the subjective comfort of passengers. Currently, the industry still lacks an effective solution that can balance structural simplicity and shifting smoothness. Summary of the Invention

[0005] Therefore, the purpose of this invention is to provide a shifting method and system for an electric drive transmission dog-tooth clutch, in order to solve the problem that the prior art cannot eliminate the shifting shock and vibration from the meshing principle level, which leads to a reduction in the driving experience of the driver and passengers.

[0006] The first aspect of the present invention proposes: A shifting method using a dog-tooth clutch in an electric drive transmission, wherein the method includes: When a shift command is received from the host computer, the dog clutch is controlled to enter the engagement preparation stage. During the engagement preparation phase, the control drive device coordinates the rotational speed of the rotating components and simultaneously displaces the gear sleeve to bring the dog clutch into the initial engagement phase. In the initial engagement stage, the target torque input to the dog clutch is controlled to enable the dog clutch to engage. During the engagement phase, the teeth of the dog clutch are aligned to complete the engagement process.

[0007] The beneficial effects of this invention are as follows: This technical solution implements phased and refined control over the shifting process of the dog-tooth clutch. After receiving the shifting command from the host computer, it first enters the engagement preparation stage, simultaneously coordinating the rotational speed of the rotating components and controlling the displacement of the gear sleeve, thus reducing the speed difference and meshing position difference in advance, laying a foundation for smooth meshing. After entering the initial engagement stage, the input target torque is precisely controlled to avoid instantaneous impact loads caused by hard contact between the teeth. During the meshing stage, tooth alignment processing is performed to eliminate vibration-induced factors such as tooth tip collision and meshing jamming from the perspective of meshing principle, achieving smooth and impact-free tooth meshing. This solution can fundamentally reduce the impact and vibration during the shifting process, significantly reduce shifting jerks, improve shifting smoothness and power connection smoothness, effectively improve the driving experience of passengers, and at the same time reduce tooth surface impact wear, extending the service life of clutch components.

[0008] Furthermore, the step of controlling the dog-tooth clutch to enter the engagement preparation stage includes: Real-time circumferential phase and real-time speed of the driving and driven components of the dog clutch, as well as the viscosity parameters of the lubricating oil inside the transmission, were collected respectively. The speed coordination reference difference is determined based on the difference in transmission ratio between the current gear and the target gear, and the speed coordination reference difference is compensated and corrected based on the viscosity parameter to obtain the final speed coordination target value. Release the axial locking structure of the gear sleeve, and record the current axial position of the gear sleeve as the starting reference point for axial displacement.

[0009] Furthermore, the step of the control drive device coordinating the rotational speed of the rotating component and simultaneously displacing the gear sleeve includes: The drive device applies closed-loop speed control to the driving component, causing the driving component to converge toward the final speed coordination target value, while simultaneously driving the gear sleeve to move axially toward the engagement side. The rate of change of the speed difference between the driving and driven components is calculated in real time, and the axial displacement rate of the gear sleeve is dynamically adjusted according to the rate of change of the speed difference. When the tooth end face of the gear sleeve and the tooth end face of the engaging gear ring are detected to be in the same axial plane, the dog tooth clutch is determined to have entered the initial engagement stage.

[0010] Furthermore, the step of controlling the target torque input to the dog clutch during the initial engagement stage includes: The first constant driving torque is output to the driving component, while the gear sleeve is continuously driven to feed axially towards the engagement side. The axial engagement depth of the gear sleeve relative to the engaging gear ring is detected in real time. When the axial engagement depth reaches the first depth threshold, the driving torque is switched to the second amplitude. When the axial engagement depth reaches the second depth threshold, the dog clutch is determined to have entered the engagement stage; wherein the second depth threshold is greater than the first depth threshold, and the second amplitude is less than the first amplitude.

[0011] Furthermore, the step of aligning the teeth of the control dog clutch includes: During the axial feeding process of the gear sleeve, the axial reaction force on the gear sleeve is collected in real time; When the fluctuation amplitude of the axial reaction force exceeds the preset fluctuation threshold, it is determined to be a tooth tip abutting state, and a small circumferential reciprocating oscillation control command is output to the drive device. When the fluctuation amplitude of the axial reaction force falls below the preset fluctuation threshold and continues for a preset duration, it is determined to be in a tooth alignment state, the small circumferential reciprocating oscillation stops, and the tooth sleeve is driven to complete the full stroke axial engagement.

[0012] Furthermore, the step of outputting a small-amplitude circumferential reciprocating oscillation control command to the driving device includes: The reference offset direction of the circumferential reciprocating oscillation is determined based on the direction of the speed difference between the current driving and driven components. Set the oscillation amplitude and oscillation frequency of the reciprocating oscillation, wherein the oscillation amplitude is less than the circumferential angle corresponding to the single tooth pitch; During the reciprocating oscillation process, the oscillation amplitude gradually decreases as the axial engagement depth of the gear sleeve increases.

[0013] Furthermore, after the engagement process is completed, the following is also included: Apply a preset amplitude of verification torque to the active component for a preset verification duration; Within the preset verification time, the speed difference between the driving and driven components and the axial displacement change of the gear sleeve are collected. When the speed difference is lower than the preset difference threshold and the axial displacement change is zero, the shift is confirmed to be complete and a shift completion feedback signal is sent to the host computer.

[0014] The second aspect of the present invention proposes: A shift control system for a dog-tooth clutch in an electric drive transmission, wherein the system comprises: The trigger module is used to receive shift commands from the host computer and control the dog clutch to enter the engagement preparation stage. The coordination module is used to control the drive device to coordinate the rotational speed of the rotating parts during the engagement preparation stage, and simultaneously displace the gear sleeve so that the dog clutch enters the initial engagement stage. The loading module is used to control the target torque input to the dog clutch during the initial engagement stage, so that the dog clutch enters the engagement stage. The execution module is used to control the alignment of the teeth of the dog clutch during the engagement phase to complete the engagement process.

[0015] Furthermore, the step of controlling the dog-tooth clutch to enter the engagement preparation stage includes: Real-time circumferential phase and real-time speed of the driving and driven components of the dog clutch, as well as the viscosity parameters of the lubricating oil inside the transmission, were collected respectively. The speed coordination reference difference is determined based on the difference in transmission ratio between the current gear and the target gear, and the speed coordination reference difference is compensated and corrected based on the viscosity parameter to obtain the final speed coordination target value. Release the axial locking structure of the gear sleeve, and record the current axial position of the gear sleeve as the starting reference point for axial displacement.

[0016] Furthermore, the step of the control drive device coordinating the rotational speed of the rotating component and simultaneously displacing the gear sleeve includes: The drive device applies closed-loop speed control to the driving component, causing the driving component to converge toward the final speed coordination target value, while simultaneously driving the gear sleeve to move axially toward the engagement side. The rate of change of the speed difference between the driving and driven components is calculated in real time, and the axial displacement rate of the gear sleeve is dynamically adjusted according to the rate of change of the speed difference. When the tooth end face of the gear sleeve and the tooth end face of the engaging gear ring are detected to be in the same axial plane, the dog tooth clutch is determined to have entered the initial engagement stage.

[0017] Furthermore, the step of controlling the target torque input to the dog clutch during the initial engagement stage includes: The first constant driving torque is output to the driving component, while the gear sleeve is continuously driven to feed axially towards the engagement side. The axial engagement depth of the gear sleeve relative to the engaging gear ring is detected in real time. When the axial engagement depth reaches the first depth threshold, the driving torque is switched to the second amplitude. When the axial engagement depth reaches the second depth threshold, the dog clutch is determined to have entered the engagement stage; wherein the second depth threshold is greater than the first depth threshold, and the second amplitude is less than the first amplitude.

[0018] Furthermore, the step of aligning the teeth of the control dog clutch includes: During the axial feeding process of the gear sleeve, the axial reaction force on the gear sleeve is collected in real time; When the fluctuation amplitude of the axial reaction force exceeds the preset fluctuation threshold, it is determined to be a tooth tip abutting state, and a small circumferential reciprocating oscillation control command is output to the drive device. When the fluctuation amplitude of the axial reaction force falls below the preset fluctuation threshold and continues for a preset duration, it is determined to be in a tooth alignment state, the small circumferential reciprocating oscillation stops, and the tooth sleeve is driven to complete the full stroke axial engagement.

[0019] Furthermore, the step of outputting a small-amplitude circumferential reciprocating oscillation control command to the driving device includes: The reference offset direction of the circumferential reciprocating oscillation is determined based on the direction of the speed difference between the current driving and driven components. Set the oscillation amplitude and oscillation frequency of the reciprocating oscillation, wherein the oscillation amplitude is less than the circumferential angle corresponding to the single tooth pitch; During the reciprocating oscillation process, the oscillation amplitude gradually decreases as the axial engagement depth of the gear sleeve increases.

[0020] Furthermore, after the engagement process is completed, the following is also included: Apply a preset amplitude of verification torque to the active component for a preset verification duration; Within the preset verification time, the speed difference between the driving and driven components and the axial displacement change of the gear sleeve are collected. When the speed difference is lower than the preset difference threshold and the axial displacement change is zero, the shift is confirmed to be complete and a shift completion feedback signal is sent to the host computer.

[0021] The third aspect of the present invention proposes: A transmission control device includes a memory, a processor, and a control program stored in the memory and executable on the processor, wherein the processor executes the control program to implement the shifting method of the dog clutch of an electric drive transmission as described above.

[0022] The fourth aspect of the present invention proposes: A computer-readable storage medium having a control program stored thereon, wherein the program, when executed by a processor, implements the shifting method of the dog clutch of an electric drive transmission as described above.

[0023] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0024] Figure 1 A flowchart illustrating the shifting method of the dog clutch in an electric drive transmission according to the first embodiment of the present invention; Figure 2 This is a structural block diagram of the shifting system of the dog-tooth clutch of the electric drive transmission provided in the third embodiment of the present invention.

[0025] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0026] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of the invention are illustrated in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0027] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0029] Please see Figure 1 The image shows a shifting method for a dog clutch in an electric drive transmission provided in the first embodiment of the present invention. The shifting method for a dog clutch in an electric drive transmission provided in this embodiment can reduce the impact and vibration during the shifting process from the source, significantly reduce the shifting jerk feeling, improve shifting smoothness and power connection smoothness, effectively improve the driving experience of the driver and passengers, and at the same time reduce tooth surface impact wear and extend the service life of the clutch components.

[0030] Specifically, this embodiment provides: A shifting method using a dog-tooth clutch in an electric drive transmission, wherein the method includes: Step S10: When a shift command is received from the host computer, the dog clutch is controlled to enter the engagement preparation stage. It should be noted that upon receiving the shift command from the host computer's vehicle controller, the system first controls the dog clutch to enter the engagement preparation stage. The core objective is to complete the pre-adjustment of the speed difference and the release of the gear sleeve lock, preparing the hardware and software for subsequent gear sleeve movement and engagement. This stage does not directly execute the engagement action; instead, it first completes the target calculation for speed coordination and unlocks the actuator to avoid overload of the actuator caused by locked gear movement. Simultaneously, pre-synchronization reduces the speed difference, laying the foundation for smooth engagement later.

[0031] Step S20: During the engagement preparation stage, the control drive device coordinates the rotational speed of the rotating parts and simultaneously displaces the gear sleeve so that the dog clutch enters the initial engagement stage. It should be noted that, based on the preparation stage, the control drive device performs closed-loop coordination of the rotation speed of the active rotating component, causing the rotation speed of the active component to converge towards that of the driven component. At the same time, it synchronously drives the gear sleeve to move axially towards the engagement side, realizing the simultaneous adjustment of rotation speed and advancement of the gear sleeve, thus shortening the overall shifting time. When the tooth end faces are flush, the initial engagement stage begins. At this time, the end faces of the gear sleeve and the engagement gear ring have just come into contact and have not yet entered the tooth groove meshing. This is the key turning point from the idle stroke to the load contact.

[0032] Step S30: In the initial engagement stage, control the target torque input to the dog clutch so that the dog clutch enters the engagement stage; It should be noted that after entering the initial engagement stage, the target torque input to the dog clutch is controlled to maintain a suitable circumferential clamping force on the tooth surface, which is then gradually engaged in conjunction with the axial feed of the tooth sleeve. The core of this stage is to control the matching of torque magnitude and feed speed, so as to ensure that the teeth slide smoothly into the tooth groove while avoiding excessive torque that would cause impact wear on the tooth surface.

[0033] Step S40: During the engagement phase, the teeth of the dog clutch are aligned to complete the engagement process.

[0034] It should be noted that during the meshing phase, in response to the problem of tooth tip aggression that is prone to occur, the teeth of the dog clutch are actively aligned. By using small circumferential oscillations, the teeth are guided to slide into the tooth grooves to complete the full stroke meshing. The alignment process solves the jamming and tooth knocking problems that are prone to occur in traditional hard push meshing and is the core control strategy for achieving smooth meshing.

[0035] Second Embodiment Furthermore, the step of controlling the dog-tooth clutch to enter the engagement preparation stage includes: Real-time circumferential phase and real-time speed of the driving and driven components of the dog clutch, as well as the viscosity parameters of the lubricating oil inside the transmission, were collected respectively. The speed coordination reference difference is determined based on the difference in transmission ratio between the current gear and the target gear, and the speed coordination reference difference is compensated and corrected based on the viscosity parameter to obtain the final speed coordination target value. Release the axial locking structure of the gear sleeve, and record the current axial position of the gear sleeve as the starting reference point for axial displacement.

[0036] It should be noted that the system collects real-time circumferential phase and real-time speed of the driving and driven components of the dog-tooth clutch, as well as the viscosity parameters of the lubricating oil inside the transmission. The circumferential phase and speed are acquired through a rotary transformer or position sensor, forming the feedback basis for speed coordination control. Lubricating oil viscosity is obtained indirectly through oil temperature conversion or directly from a viscosity sensor. The viscosity directly affects the oil churning resistance during shifting, the lubrication state of the gear teeth, and the resistance to gear sleeve movement. At low temperatures and high viscosity, the gear sleeve propulsion resistance is high, and the control tolerance for speed differences also needs to be adjusted accordingly. Simultaneous acquisition of multiple parameters ensures that subsequent control targets can adapt to the current actual operating conditions, rather than using fixed values ​​that result in poor adaptability.

[0037] Based on the difference in transmission ratio between the current gear and the target gear, the theoretical speed coordination benchmark difference is calculated. This is the target speed that the driving component needs to achieve under ideal conditions, ensuring transmission ratio matching before and after engagement. Then, the speed coordination benchmark difference is compensated and corrected based on the lubricating oil viscosity parameters. Under low temperature and high viscosity conditions, the target speed difference is appropriately amplified to allow sufficient tooth groove slippage, preventing excessively small speed differences and tooth tip hardening due to oil resistance. Under high temperature and low viscosity conditions, the speed difference is reduced to decrease meshing impact. The final speed coordination target value obtained after correction takes into account both the theoretical transmission ratio requirements and the influence of actual oil conditions, exhibiting stronger adaptability to operating conditions than fixed speed difference control.

[0038] Release the axial locking structure of the gear sleeve, that is, disengage the locking steel ball or self-locking mechanism of the original position, releasing the axial degree of freedom of the gear sleeve; at the same time, record the current axial position of the gear sleeve as the starting reference point for axial displacement. All subsequent calculations of engagement depth and displacement rate are based on this reference point, ensuring the accuracy of axial displacement control. Unlocking and reference calibration are completed simultaneously, which not only avoids damage to the mechanism caused by shifting gears while locked, but also provides an accurate zero-point reference for displacement closed-loop control.

[0039] Furthermore, the step of the control drive device coordinating the rotational speed of the rotating component and simultaneously displacing the gear sleeve includes: The drive device applies closed-loop speed control to the driving component, causing the driving component to converge toward the final speed coordination target value, while simultaneously driving the gear sleeve to move axially toward the engagement side. The rate of change of the speed difference between the driving and driven components is calculated in real time, and the axial displacement rate of the gear sleeve is dynamically adjusted according to the rate of change of the speed difference. When the tooth end face of the gear sleeve and the tooth end face of the engaging gear ring are detected to be in the same axial plane, the dog tooth clutch is determined to have entered the initial engagement stage.

[0040] It should be noted that the drive device, i.e., the drive motor, applies closed-loop speed control to the active component, causing the speed of the active component to gradually converge towards the final coordinated target value. Simultaneously, the gear sleeve is driven axially towards the engagement side through the shifting actuator. Traditional shifting control often uses a serial logic of "synchronizing speed first, then moving the gear sleeve," resulting in a long shifting time. This method uses parallel collaborative control, synchronously advancing the gear sleeve's idle stroke during the speed convergence process. When the speed difference shrinks to a reasonable range, the gear sleeve just reaches the engagement end face, significantly reducing the total shifting time and adapting to the stringent requirements of electric drive systems for shifting power interruption time.

[0041] The system calculates the rate of change of the speed difference between the driving and driven components in real time, i.e., the convergence speed of the speed difference, and dynamically adjusts the axial displacement rate of the gear sleeve based on this rate of change. When the speed difference converges quickly and the downward slope is large, it indicates good speed synchronization, and the gear sleeve displacement rate can be appropriately increased to further accelerate the shifting rhythm. When the speed difference converges slowly and fluctuates greatly, the gear sleeve displacement rate is reduced to avoid hard contact of the tooth end faces under large speed differences, which could cause tooth breakage. The dynamic speed regulation mechanism ensures that the gear sleeve feed speed is always matched with the speed synchronization state, achieving an optimal balance between speed and smoothness.

[0042] When the tooth end face of the gear sleeve and the tooth end face of the engaging gear ring are detected to be in the same axial plane, the dog clutch is determined to have entered the initial engagement stage. This determination is usually confirmed by combining the position signal from the axial displacement sensor with the axial force abrupt change signal. When the displacement reaches the theoretical end face position and the axial reaction force shows a step increase, it indicates that the tooth ends have made contact. Initial engagement is a critical dividing point in the shifting process. Before this, there is a no-contact free travel; after this, the engagement travel with contact begins, which is also the starting point for subsequent torque grading control.

[0043] Furthermore, the step of controlling the target torque input to the dog clutch during the initial engagement stage includes: The first constant driving torque is output to the driving component, while the gear sleeve is continuously driven to feed axially towards the engagement side. The axial engagement depth of the gear sleeve relative to the engaging gear ring is detected in real time. When the axial engagement depth reaches the first depth threshold, the driving torque is switched to the second amplitude. When the axial engagement depth reaches the second depth threshold, the dog clutch is determined to have entered the engagement stage; wherein the second depth threshold is greater than the first depth threshold, and the second amplitude is less than the first amplitude.

[0044] It should be noted that after entering the initial engagement stage, a constant driving torque of the first amplitude is output to the driving component, while the gear sleeve is continuously driven to feed axially towards the engagement side. The first amplitude is a relatively large torque value, the purpose of which is to maintain a stable circumferential clamping force on the end faces of the driving and driven teeth, preventing tooth surface slippage that could lead to engagement failure, and providing sufficient circumferential driving force for the teeth to slide into the tooth groove along the guide surface. In this stage, the teeth only contact each other on the end faces, resulting in a large contact area. The large torque will not cause serious wear; on the contrary, it can improve the initial engagement response speed.

[0045] The axial engagement depth of the gear sleeve relative to the engaging gear ring is monitored in real time. When the axial engagement depth reaches the first depth threshold, it indicates that the tooth has slid past the tooth tip chamfer and begun to enter the tooth groove. At this point, the drive torque is switched to a smaller second amplitude. After entering the tooth groove, the tooth flanks begin to contact. If a large torque is maintained, it will cause impact wear on the tooth flanks. Therefore, the torque amplitude is reduced, allowing the tooth to engage slowly with a lower circumferential force, effectively reducing meshing impact and tooth surface stress. The graded torque switching precisely matches the tooth surface contact state at different engagement depths, avoiding the impact problem of high torque throughout the entire range and the engagement difficulty problem of low torque throughout the entire range.

[0046] When the axial engagement depth reaches the second depth threshold, the dog clutch is determined to have entered the engagement stage. The second depth threshold being greater than the first depth threshold indicates that the teeth have completed most of the engagement stroke, entering the final alignment and full-stroke engagement stage. These two depth thresholds divide the initial engagement stage into two sub-stages: end-face contact and half-stroke engagement, each matched with different torque levels, achieving refined control of the engagement process.

[0047] Furthermore, the step of aligning the teeth of the control dog clutch includes: During the axial feeding process of the gear sleeve, the axial reaction force on the gear sleeve is collected in real time; When the fluctuation amplitude of the axial reaction force exceeds the preset fluctuation threshold, it is determined to be a tooth tip abutting state, and a small circumferential reciprocating oscillation control command is output to the drive device. When the fluctuation amplitude of the axial reaction force falls below the preset fluctuation threshold and continues for a preset duration, it is determined to be in a tooth alignment state, the small circumferential reciprocating oscillation stops, and the tooth sleeve is driven to complete the full stroke axial engagement.

[0048] It should be noted that during the axial feeding of the gear sleeve, the axial reaction force acting on the gear sleeve is collected in real time. This force can be indirectly calculated through the current, force sensors, or displacement difference of the shifting actuator. During normal sliding into the tooth groove, the axial reaction force rises smoothly with minimal fluctuation. When tooth tips collide, the teeth collide, causing violent high-frequency fluctuations in the axial reaction force. By monitoring whether the fluctuation amplitude exceeds a preset fluctuation threshold, it is possible to accurately determine whether the current state is one of tooth tip collision or normal sliding. Force feedback recognition does not require an additional position phase sensor; it relies on the signal from the actuator itself, resulting in low cost and fast response.

[0049] When the tooth tips are determined to be in a contacting state, a small-amplitude circumferential reciprocating oscillation control command is output to the drive unit, controlling the driving component to rotate back and forth at a small angle, causing the tooth tips to slide slightly on the end face of the driven tooth to find the tooth groove entry. The reciprocating oscillation replaces the traditional method of hard pushing the tooth sleeve during gear shifting, avoiding the risk of tooth surface plastic deformation and tooth breakage caused by prolonged hard contact of the tooth tips. At the same time, relying on the guiding effect of the tooth tip chamfer, the tooth is guided to slide naturally into the tooth groove, greatly improving the smoothness of meshing.

[0050] When the amplitude of the axial reaction force fluctuation falls below the preset fluctuation threshold and remains below it for a preset duration, it indicates that the tooth tip has slid into the tooth groove and the tooth side is stably engaged, indicating that the tooth groove is aligned. At this point, the small circumferential reciprocating oscillation stops, and the gear sleeve is continuously driven to complete the full stroke of axial engagement until the engagement endpoint is reached. Precise control of the oscillation stop timing ensures that the tooth groove is fully aligned before advancing the full stroke, avoiding mid-journey jamming, and also avoids unnecessary continuous oscillation that prolongs the shifting time.

[0051] Furthermore, the step of outputting a small-amplitude circumferential reciprocating oscillation control command to the driving device includes: The reference offset direction of the circumferential reciprocating oscillation is determined based on the direction of the speed difference between the current driving and driven components. Set the oscillation amplitude and oscillation frequency of the reciprocating oscillation, wherein the oscillation amplitude is less than the circumferential angle corresponding to the single tooth pitch; During the reciprocating oscillation process, the oscillation amplitude gradually decreases as the axial engagement depth of the gear sleeve increases.

[0052] It should be noted that the reference offset direction for the circumferential reciprocating oscillation is determined based on the direction of the speed difference between the driving and driven components. In other words, the center offset direction of the oscillation is consistent with the direction of the speed difference. This design ensures that the oscillation always occurs along the direction of speed convergence, preventing the speed difference from widening in the opposite direction. This not only helps to accelerate the slot finding speed but also ensures that the speed difference remains within a reasonable range after engagement, avoiding speed synchronization failure caused by oscillation.

[0053] The amplitude and frequency of the reciprocating oscillation are set, with the amplitude being strictly smaller than the circumferential angle corresponding to a single tooth pitch, typically controlled between 1 / 3 and 1 / 2 of the single tooth pitch. An amplitude smaller than the single tooth pitch ensures that the oscillation always occurs within the range of two adjacent teeth, preventing skipping multiple teeth and causing misalignment or tooth breakage, thus ensuring the safety of the slotting process. The oscillation frequency is set according to the response bandwidth of the actuator, typically ranging from a few hertz to tens of hertz, balancing slotting efficiency and system stability.

[0054] During the reciprocating oscillation process, the oscillation amplitude gradually decreases as the axial engagement depth of the gear sleeve increases. This is because the deeper the teeth engage, the stronger the guiding effect of the tooth flanks and the smaller the circumferential degree of freedom of the teeth, so that alignment can be completed without a large oscillation amplitude; at the same time, the decreasing amplitude also avoids the impact and wear of the tooth flanks caused by large oscillations in the deep engagement state, allowing the oscillation action to gradually converge with the engagement depth, and finally smoothly transition to the fully engaged state, achieving a smooth connection from slot finding to locking.

[0055] Furthermore, after the engagement process is completed, the following is also included: Apply a preset amplitude of verification torque to the active component for a preset verification duration; Within the preset verification time, the speed difference between the driving and driven components and the axial displacement change of the gear sleeve are collected. When the speed difference is lower than the preset difference threshold and the axial displacement change is zero, the shift is confirmed to be complete and a shift completion feedback signal is sent to the host computer.

[0056] It should be noted that after full engagement, a preset amplitude verification torque is applied to the driving component for a preset verification duration. The amplitude of the verification torque is usually greater than the average operating torque during normal driving, simulating the stress state under actual load conditions. The purpose is to check whether the clutch will slip or disengage under load, and to eliminate false engagement states where the teeth are not fully engaged. False engagement is a common failure mode of dog clutches. Externally, the gear sleeve appears to be in place, but in reality, only a small portion of the tooth surface overlaps, making it extremely prone to slippage under load. Applying the verification torque can effectively expose these hidden dangers and ensure shifting reliability.

[0057] Within a preset verification period, two core indicators are simultaneously collected: the speed difference between the driving and driven components and the axial displacement change of the gear sleeve. A speed difference below a preset threshold indicates that the driving and driven components rotate synchronously without slippage, ensuring stable torque transmission. Zero axial displacement indicates no sleeve backing, confirming reliable axial locking. These two dimensions verify the reliability of circumferential transmission and axial locking, respectively. Both conditions must be met simultaneously to confirm effective meshing; achieving only one dimension is insufficient for completion, thus avoiding the risk of misjudgment based on a single indicator.

[0058] When both the speed difference and axial displacement meet the requirements, the gear shift is confirmed to be complete, a gear shift completion feedback signal is sent to the host vehicle controller, and normal drive torque control is restored. This closed-loop verification mechanism adds a final safety check to the entire gear shifting process, ensuring reliable engagement for each shift, improving the safety and durability of the transmission, and providing accurate status feedback for the vehicle's power control.

[0059] Please see Figure 2 The third embodiment of the present invention provides: A shift control system for a dog-tooth clutch in an electric drive transmission, wherein the system comprises: The trigger module is used to receive shift commands from the host computer and control the dog clutch to enter the engagement preparation stage. The coordination module is used to control the drive device to coordinate the rotational speed of the rotating parts during the engagement preparation stage, and simultaneously displace the gear sleeve so that the dog clutch enters the initial engagement stage. The loading module is used to control the target torque input to the dog clutch during the initial engagement stage, so that the dog clutch enters the engagement stage. The execution module is used to control the alignment of the teeth of the dog clutch during the engagement phase to complete the engagement process.

[0060] Furthermore, the step of controlling the dog-tooth clutch to enter the engagement preparation stage includes: Real-time circumferential phase and real-time speed of the driving and driven components of the dog clutch, as well as the viscosity parameters of the lubricating oil inside the transmission, were collected respectively. The speed coordination reference difference is determined based on the difference in transmission ratio between the current gear and the target gear, and the speed coordination reference difference is compensated and corrected based on the viscosity parameter to obtain the final speed coordination target value. Release the axial locking structure of the gear sleeve, and record the current axial position of the gear sleeve as the starting reference point for axial displacement.

[0061] Furthermore, the step of the control drive device coordinating the rotational speed of the rotating component and simultaneously displacing the gear sleeve includes: The drive device applies closed-loop speed control to the driving component, causing the driving component to converge toward the final speed coordination target value, while simultaneously driving the gear sleeve to move axially toward the engagement side. The rate of change of the speed difference between the driving and driven components is calculated in real time, and the axial displacement rate of the gear sleeve is dynamically adjusted according to the rate of change of the speed difference. When the tooth end face of the gear sleeve and the tooth end face of the engaging gear ring are detected to be in the same axial plane, the dog tooth clutch is determined to have entered the initial engagement stage.

[0062] Furthermore, the step of controlling the target torque input to the dog clutch during the initial engagement stage includes: The first constant driving torque is output to the driving component, while the gear sleeve is continuously driven to feed axially towards the engagement side. The axial engagement depth of the gear sleeve relative to the engaging gear ring is detected in real time. When the axial engagement depth reaches the first depth threshold, the driving torque is switched to the second amplitude. When the axial engagement depth reaches the second depth threshold, the dog clutch is determined to have entered the engagement stage; wherein the second depth threshold is greater than the first depth threshold, and the second amplitude is less than the first amplitude.

[0063] Furthermore, the step of aligning the teeth of the control dog clutch includes: During the axial feeding process of the gear sleeve, the axial reaction force on the gear sleeve is collected in real time; When the fluctuation amplitude of the axial reaction force exceeds the preset fluctuation threshold, it is determined to be a tooth tip abutting state, and a small circumferential reciprocating oscillation control command is output to the drive device. When the fluctuation amplitude of the axial reaction force falls below the preset fluctuation threshold and continues for a preset duration, it is determined to be in a tooth alignment state, the small circumferential reciprocating oscillation stops, and the tooth sleeve is driven to complete the full stroke axial engagement.

[0064] Furthermore, the step of outputting a small-amplitude circumferential reciprocating oscillation control command to the driving device includes: The reference offset direction of the circumferential reciprocating oscillation is determined based on the direction of the speed difference between the current driving and driven components. Set the oscillation amplitude and oscillation frequency of the reciprocating oscillation, wherein the oscillation amplitude is less than the circumferential angle corresponding to the single tooth pitch; During the reciprocating oscillation process, the oscillation amplitude gradually decreases as the axial engagement depth of the gear sleeve increases.

[0065] Furthermore, after the engagement process is completed, the following is also included: Apply a preset amplitude of verification torque to the active component for a preset verification duration; Within the preset verification time, the speed difference between the driving and driven components and the axial displacement change of the gear sleeve are collected. When the speed difference is lower than the preset difference threshold and the axial displacement change is zero, the shift is confirmed to be complete and a shift completion feedback signal is sent to the host computer.

[0066] The fourth embodiment of the present invention provides a transmission control device, including a memory, a processor, and a control program stored in the memory and executable on the processor, wherein the processor executes the control program to implement the shifting method of the dog clutch of the electric drive transmission as described above.

[0067] The fifth embodiment of the present invention provides a computer-readable storage medium having a control program stored thereon, wherein the program, when executed by a processor, implements the shifting method of the dog clutch of the electric drive transmission as described above.

[0068] In summary, the shifting method and system of the electric drive transmission dog clutch provided in the above embodiments of the present invention can fundamentally reduce the impact and vibration during the shifting process, significantly reduce shifting jerks, improve shifting smoothness and power connection smoothness, effectively improve the driving experience of drivers and passengers, and at the same time reduce tooth surface impact wear and extend the service life of clutch components.

[0069] It should be noted that the above modules can be functional modules or program modules, and can be implemented through software or hardware. For modules implemented through hardware, the above modules can reside in the same processor; or the above modules can be located in different processors in any combination.

[0070] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-including system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0071] More specific examples of computer-readable media (a non-exhaustive list) include: electrical connections (electronic devices) having one or more wires, portable computer disk drives (magnetic devices), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Furthermore, computer-readable media can even be paper or other suitable media on which the program can be printed, because the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in computer memory.

[0072] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0073] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0074] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A shifting method using a dog-tooth clutch in an electric drive transmission, characterized in that, The method includes: When a shift command is received from the host computer, the dog clutch is controlled to enter the engagement preparation stage. During the engagement preparation phase, the control drive device coordinates the rotational speed of the rotating components and simultaneously displaces the gear sleeve to bring the dog clutch into the initial engagement phase. In the initial engagement stage, the target torque input to the dog clutch is controlled so that the dog clutch enters the engagement stage; During the engagement phase, the teeth of the dog clutch are aligned to complete the engagement process.

2. The shifting method of the electric drive transmission dog clutch according to claim 1, characterized in that, The steps for controlling the dog clutch to enter the engagement preparation stage include: Real-time circumferential phase and real-time speed of the driving and driven components of the dog clutch, as well as the viscosity parameters of the lubricating oil inside the transmission, were collected respectively. The speed coordination reference difference is determined based on the difference in transmission ratio between the current gear and the target gear, and the speed coordination reference difference is compensated and corrected based on the viscosity parameter to obtain the final speed coordination target value. Release the axial locking structure of the gear sleeve, and record the current axial position of the gear sleeve as the starting reference point for axial displacement.

3. The shifting method of the electric drive transmission dog clutch according to claim 2, characterized in that, The steps of the control drive device coordinating the rotational speed of the rotating component and simultaneously displacing the gear sleeve include: The drive device applies closed-loop speed control to the driving component, causing the driving component to converge toward the final speed coordination target value, while simultaneously driving the gear sleeve to move axially toward the engagement side. The rate of change of the speed difference between the driving and driven components is calculated in real time, and the axial displacement rate of the gear sleeve is dynamically adjusted according to the rate of change of the speed difference. When the tooth end face of the gear sleeve and the tooth end face of the engaging gear ring are detected to be in the same axial plane, the dog tooth clutch is determined to have entered the initial engagement stage.

4. The shifting method of the dog-tooth clutch in the electric drive transmission according to claim 1, characterized in that, The step of controlling the target torque input to the dog clutch during the initial engagement stage includes: The first constant driving torque is output to the driving component, while the gear sleeve is continuously driven to feed axially towards the engagement side. The axial engagement depth of the gear sleeve relative to the engaging gear ring is detected in real time. When the axial engagement depth reaches the first depth threshold, the driving torque is switched to the second amplitude. When the axial engagement depth reaches the second depth threshold, the dog clutch is determined to have entered the engagement stage; wherein the second depth threshold is greater than the first depth threshold, and the second amplitude is less than the first amplitude.

5. The shifting method of the dog-tooth clutch in the electric drive transmission according to claim 1, characterized in that, The step of aligning the teeth of the control dog clutch includes: During the axial feeding process of the gear sleeve, the axial reaction force on the gear sleeve is collected in real time; When the fluctuation amplitude of the axial reaction force exceeds the preset fluctuation threshold, it is determined to be a tooth tip abutting state, and a small circumferential reciprocating oscillation control command is output to the drive device. When the fluctuation amplitude of the axial reaction force falls below the preset fluctuation threshold and continues for a preset duration, it is determined to be in a tooth alignment state, the small circumferential reciprocating oscillation stops, and the tooth sleeve is driven to complete the full stroke axial engagement.

6. The shifting method of the dog-tooth clutch in the electric drive transmission according to claim 5, characterized in that, The step of outputting a small-amplitude circumferential reciprocating oscillation control command to the drive device includes: The reference offset direction of the circumferential reciprocating oscillation is determined based on the direction of the speed difference between the current driving and driven components. Set the oscillation amplitude and oscillation frequency of the reciprocating oscillation, wherein the oscillation amplitude is less than the circumferential angle corresponding to the single tooth pitch; During the reciprocating oscillation process, the oscillation amplitude gradually decreases as the axial engagement depth of the gear sleeve increases.

7. The shifting method of the dog-tooth clutch in an electric drive transmission according to claim 1, characterized in that, After the engagement process is completed, the following is also included: Apply a preset amplitude of verification torque to the active component for a preset verification duration; Within the preset verification time, the speed difference between the driving and driven components and the axial displacement change of the gear sleeve are collected. When the speed difference is lower than the preset difference threshold and the axial displacement change is zero, the shift is confirmed to be complete and a shift completion feedback signal is sent to the host computer.

8. A shift control system for a dog-tooth clutch in an electric drive transmission, characterized in that, The system includes: The trigger module is used to receive shift commands from the host computer and control the dog clutch to enter the engagement preparation stage. The coordination module is used to control the drive device to coordinate the rotational speed of the rotating parts during the engagement preparation stage, and simultaneously displace the gear sleeve so that the dog clutch enters the initial engagement stage. The loading module is used to control the target torque input to the dog clutch during the initial engagement stage, so that the dog clutch enters the engagement stage. The execution module is used to control the alignment of the teeth of the dog clutch during the engagement phase to complete the engagement process.

9. A transmission control device, comprising a memory, a processor, and a control program stored in the memory and executable on the processor, characterized in that, When the processor executes the control program, it implements the shifting method of the dog clutch of the electric drive transmission as described in any one of claims 1 to 7.

10. A computer-readable storage medium having a control program stored thereon, characterized in that, When executed by the processor, the program implements the shifting method of the dog clutch of the electric drive transmission as described in any one of claims 1 to 7.

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