Electric drive axle 2AMT gear shifting method and gear shifting executing mechanism

Abstract

The invention discloses an electric drive axle 2AMT gear shifting method and a gear shifting executing mechanism. The gear shifting method comprises the steps that firstly, the torque of a driving motor of an electric drive axle is controlled to be reduced to 0; then, the gear taking-off action is executed, and the combination sleeve is driven to move to the critical gear taking-off position; then the rotating speed of the driving motor is adjusted according to the rotating speed required by the target gear, so that the difference between the rotating speed of the combination sleeve and the rotating speed of the combination gear of the target gear is r, and r is larger than 0 and smaller than or equal to 15 r / min; meanwhile, the combination sleeve continues to move to the critical gear engaging position of the target gear; after speed regulation is completed, the combination sleeve is moved to the position where the combination sleeve is completely meshed with the target-gear combination gear; and finally, the torque of the driving motor is recovered according to the current whole vehicle requirement, and the 2AMT gear shifting process of the electric drive axle is completed. By means of the method, the time required for gear shifting execution is shortened, and the power interruption time is shortened.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicles, and particularly relates to a 2AMT shifting method and a shifting actuator for an electric drive axle. Background Art

[0002] With the continuous development of new energy commercial vehicle technology, the integrated electric drive axle has been widely used due to its advantages such as high integration and low energy consumption. However, in the field of heavy commercial vehicles, limited by the motor speed and the high-efficiency working range, in order to simultaneously meet the requirements of high vehicle speed, large output torque and low energy consumption, a multi-speed transmission mechanism is often used for adjustment, especially the two-speed transmission mechanism is the most common.

[0003] The two-speed transmission mechanism of the electric drive axle is the same as the shifting structure of the traditional gearbox, and the power transmission between different speed ratio gear pairs and the transmission shaft is realized under the action of the synchronizer sleeve to complete the two-speed adjustment. Conventional two-speed adjustment methods all adopt a multi-link series connection method. For example, when shifting from the first gear to the second gear, the process includes single control of the axial movement of the synchronizer sleeve by displacement or speed, and the series connection of torque reduction, gear disengagement, speed regulation, gear engagement and torque restoration are carried out, and each link does not affect each other; although this shifting method can basically meet the shifting and speed change requirements of the integrated electric drive axle, due to the single control method of the axial movement of the synchronizer sleeve and the series connection of the shifting execution links, there are problems of low shifting efficiency and long power interruption time. At the same time, there is no proper matching relationship between the single synchronizer sleeve movement control method and the shifting links, and the vehicle is prone to faults such as shifting jerks and emergency stalls, seriously affecting the driving experience and safety of the vehicle. Summary of the Invention

[0004] In order to solve the above problems existing in the prior art, the present invention provides a 2AMT shifting method and a shifting actuator for an electric drive axle. The technical problems to be solved by the present invention are realized through the following technical solutions:

[0005] A 2AMT shifting method for an electric drive axle includes:

[0006] Step 1: First, control the torque of the drive motor of the electric drive axle to drop to 0;

[0007] Step 2: Then perform a gear disengagement action to drive the synchronizer sleeve to move to the critical gear disengagement position;

[0008] Step 3: Then adjust the speed of the drive motor according to the required speed of the target gear, so that the speed difference between the synchronizer sleeve speed and the target gear engagement gear speed is r, where 0 < r ≤ 15 r / min; at the same time, continue to move the synchronizer sleeve to the critical gear engagement position of the target gear;

[0009] Step 4: After the speed regulation is completed, move the synchronizer sleeve to the fully engaged position with the target gear engagement gear;

[0010] Step 5: Finally, restore the torque of the drive motor according to the current vehicle demand to complete the 2AMT shifting process of the electric drive axle.

[0011] Further, in the step 3, the shift sleeve is moved to the critical gear engagement position of the target gear by means of displacement control.

[0012] Further, the step 4 includes:

[0013] Step 4.1: After the speed regulation is completed, first move the shift sleeve accurately to the position where it starts to engage with the engagement gear of the target gear by means of speed control;

[0014] Step 4.2: Then, quickly push the shift sleeve to the position where it is fully engaged with the engagement gear of the target gear by means of displacement control.

[0015] Further, in the step 4.1: when moving the shift sleeve by means of speed control, the axial moving speed of the shift sleeve is v, and 0.1mm / 2ms ≤ v ≤ 0.15mm / 2ms.

[0016] Further, in the step 2, the calculation process of the critical gear disengagement position is as follows:

[0017] Step 2.1: First, engage a certain gear, that is, the shift sleeve engages with any one of the first-gear transmission gear or the second-gear transmission gear. The drive motor operates at a fixed speed. After the speed of the shift shaft is stable, the shift sleeve moves towards the neutral position at the current fixed speed for gear disengagement, and record the speed of the shift shaft during the movement of the shift sleeve;

[0018] Step 2.2: When the speed of the shift shaft starts to decrease, the shift sleeve stops moving, record the position of the shift sleeve at the current moment, and observe whether the speed of the shift shaft keeps decreasing to 0;

[0019] Step 2.3: If the speed of the shift shaft continues to decrease to 0, repeat the above steps 3 times, and record the position of the shift sleeve when the speed of the shift shaft starts to decrease, and calculate the average value of the 3 times to obtain the critical gear disengagement position;

[0020] Step 2.4: If the speed of the shift shaft stops decreasing and maintains a fixed speed before dropping to 0, then make the shift sleeve continue to move towards the neutral position at a fixed speed. When the speed of the shift shaft starts to decrease again, the shift sleeve stops moving, record the position of the shift sleeve at the current moment, and observe whether the speed of the shift shaft keeps decreasing to 0;

[0021] Step 2.5: If so, repeat steps 2.1 to 2.4 to obtain the critical gear disengagement position.

[0022] Furthermore, the critical gear engagement position = the critical gear disengagement position when changing to the opposite gear - the safety margin; the safety margin is a, where 0 ≤ a ≤ 2 mm.

[0023] Another embodiment of the present invention further provides an electric drive axle 2AMT shift execution structure for executing the electric drive axle 2AMT shift method, including: a shift shaft, a first - gear drive gear, a second - gear drive gear, a spline hub, and a synchromesh sleeve; the first - gear drive gear, the second - gear drive gear, and the spline hub are all sleeved on the shift shaft; a sliding component is arranged between the first - gear drive gear, the second - gear drive gear and the shift shaft, and the spline hub is connected to the shift shaft through internal and external splines; the synchromesh sleeve is sleeved on the outside of the spline hub through internal splines and can achieve axial movement under the action of an external shift power source.

[0024] Furthermore, the external shift power source is electric or hydraulic actuation.

[0025] Advantages of the present invention:

[0026] 1. High shift efficiency and short power interruption time: Adopting the shift control logic of "disengaging while adjusting, adjusting while engaging", by starting to adjust the speed when the synchromesh sleeve moves to the critical gear disengagement position and stopping the speed adjustment until the synchromesh sleeve moves to the critical gear engagement position, that is, during the period when the synchromesh sleeve moves from the critical gear disengagement position to neutral and then from neutral to the critical gear engagement position, all are used for speed adjustment, realizing the parallel development of shift execution and motor speed regulation, greatly shortening the time required for shift execution, improving the shift execution efficiency, reducing the power interruption time, and enhancing the shift efficiency;

[0027] 2. Smooth shifting without jerks: The axial movement of the synchromesh sleeve adopts a composite control method of displacement control and speed control. First, between the start of gear disengagement and the critical gear engagement position, the synchromesh sleeve is quickly moved to the critical gear engagement position through displacement control (the adjustment speed is much greater than speed control). Then, between the critical gear engagement position and the position where the synchromesh sleeve starts to mesh with the target - gear engagement gear, the linear axial movement of the synchromesh sleeve is precisely adjusted through speed control to achieve a smooth meshing transition between the power - transmission gears, thereby greatly reducing the torque mutation phenomenon caused by shifting, effectively improving the shift smoothness, ensuring the driving safety of the vehicle, and at the same time improving the driving experience of the vehicle; finally, the synchromesh sleeve is quickly moved to the position where it is fully meshed with the target - gear engagement gear through displacement control, reducing the shift time and improving the shift efficiency.

[0028] The following will further elaborate on the present invention in detail with reference to the drawings and embodiments. Description of the Drawings

[0029] Figure 1Schematic diagram of the structure of the 2AMT shift actuator for the electric drive axle of the present invention;

[0030] Figure 2 Process schematic diagram of the 2AMT shift method for the electric drive axle of the present invention;

[0031] Figure 3 Schematic diagram of the critical gear disengaging position in the 2AMT shift method for the electric drive axle of the present invention.

[0032] Description of reference numerals

[0033] 1 - Shift shaft; 2 - First - gear drive gear; 3 - Second - gear drive gear; 4 - Spline hub; 5 - Clutch sleeve. Detailed implementation manners

[0034] The following further describes the present invention in detail with reference to specific embodiments, but the implementation manners of the present invention are not limited thereto.

[0035] Embodiment 1

[0036] Please refer to Figure 1 , an embodiment of the present invention provides a 2AMT shift actuator for an electric drive axle, specifically including a shift shaft 1, a first - gear drive gear 2, a second - gear drive gear 3, a spline hub 4, and a clutch sleeve 5; the first - gear drive gear 2, the second - gear drive gear 3, and the spline hub 4 are all sleeved on the shift shaft 1, and a sliding component is provided between the first - gear drive gear 2, the second - gear drive gear 3 and the shift shaft 1, and this sliding component can specifically be a needle bearing; the spline hub 4 and the shift shaft 1 are connected through internal and external splines (the inner surface of the spline hub 4 has internal splines, and the surface of the shift shaft 1 has external splines); the clutch sleeve 5 is sleeved outside the spline hub 4 through its internal splines and can achieve axial movement under the action of an external shift power source.

[0037] Preferably, the external shift power source is electric or hydraulic actuation.

[0038] Embodiment 2

[0039] Please refer to Figures 2 - 3 , an embodiment of the present invention provides a 2AMT shift method for an electric drive axle. This shift method utilizes the 2AMT shift actuator structure in Embodiment 1. This shift method specifically includes the following steps:

[0040] The 2AMT shift method for the electric drive axle specifically includes:

[0041] Step 1: The electric drive bridge shift controller determines whether to execute a shift command based on the vehicle status information received from the CAN bus, in combination with the actual gear position of the current electric drive bridge, the shift shaft speed, and the shift motor status, and comprehensively considering the actual operating conditions of the vehicle. Among them, the vehicle status information includes the position of the vehicle shift lever, the throttle pedal opening, the brake pedal opening, the drive motor speed, the drive motor torque, and the drive motor fault code.

[0042] Step 2: If the shift controller determines that the shift command can be executed currently, it first controls the drive motor torque to drop to 0, so that the gear disengaging process can proceed smoothly; this process occurs Figure 2 during the time period t0 - t1 in

[0043] Step 3: Then, execute the gear disengaging action to drive the synchronizer sleeve to move to the critical gear disengaging position; this process occurs Figure 2 during the time period t1 - t2 in

[0044] The calculation process of the critical gear disengaging position is as follows:

[0045] Step 3.1: First, engage a certain gear, that is, the synchronizer sleeve meshes with any one of the first - gear transmission gear or the second - gear transmission gear. The drive motor operates at a fixed speed. After the shift shaft speed stabilizes, the synchronizer sleeve moves towards the neutral position at the current fixed speed for gear disengaging. During the movement of the synchronizer sleeve, record the drive motor speed and the shift shaft speed.

[0046] Step 3.2: When the shift shaft speed starts to decrease, the synchronizer sleeve stops moving, record the position of the synchronizer sleeve at the current moment, and observe whether the shift shaft speed keeps decreasing to 0.

[0047] Step 3.3: If the shift shaft speed continuously decreases to 0, repeat the above steps 3 times, and record the position of the synchronizer sleeve when the shift shaft speed starts to decrease, that is, the distance between the synchronizer sleeve and the neutral position. Calculate the average value of the 3 times to obtain the critical gear disengaging position.

[0048] Step 3.4: If the shift shaft speed stops decreasing and maintains a fixed speed before dropping to 0, make the synchronizer sleeve continue to move towards the neutral position at a fixed speed. When the shift shaft speed starts to decrease again, the synchronizer sleeve stops moving, record the position of the synchronizer sleeve at the current moment, and observe whether the shift shaft speed keeps decreasing to 0.

[0049] Step 3.5: If so, repeat steps 3.1 - 3.4 to obtain the critical gear disengaging position.

[0050] Step 4: Then, adjust the speed of the drive motor according to the required speed of the target gear position, so that the speed difference between the speed of the synchronizer sleeve and the speed of the engaging gear of the target gear position is r, where 0 < r ≤ 15 r / min; meanwhile, continue to move the synchronizer sleeve to the critical gear engagement position of the target gear position; the speed adjustment process occurs during Figure 2 the time period of t2 - t4 in Figure 2 ; the movement process of the synchronizer sleeve occurs during the time period of t2 - t3 in

[0051] The purpose of adjusting the motor speed is to keep the speed difference between the synchronizer sleeve and the engaging gear of the target gear position within a certain range, which is convenient for the smooth progress of the gear shifting process. An excessive speed difference will cause excessive wear of the transmission gears, abnormal noise during gear shifting, and excessive gear shifting impact. When the speed difference is 0, it will cause the two gears that need to be engaged to be unable to shift gears when the tooth tips are facing each other. Therefore, a certain speed difference must be ensured before the synchronizer sleeve and the engaging gear of the target gear position are engaged.

[0052] The critical gear engagement position = the critical gear disengagement position when changing to the opposite gear - safety margin; that is, the critical gear engagement position when shifting from gear 1 to gear 2 is the position where the critical gear disengagement position when shifting from gear 2 to gear 1 is shifted one safety margin further towards the neutral position, ensuring the reliability of gear shifting; the safety margin is a, where 0 ≤ a ≤ 2 mm; in the embodiment of the present invention, a = 0.5 mm. As Figure 2 shown, the critical disengagement position P_2 for shifting from gear 2 to gear 1 is the critical gear disengagement position when shifting from gear 2 to gear 1, the critical engagement position P_1 for shifting from gear 1 to gear 2 is the critical gear engagement position when shifting from gear 1 to gear 2, and P_0 is the neutral position, taken as the origin 0. Then, the value of the critical engagement distance of P_1 from the origin 0 (taking the positive value) = the value of the critical disengagement distance of P_2 from the origin 0 (taking the positive value) - 0.5 mm.

[0053] Specifically, the synchronizer sleeve is moved to the critical gear engagement position of the target gear position by means of displacement control, thereby reducing the gear shifting time and improving the gear shifting efficiency.

[0054] Step 5: After the speed adjustment is completed, move the synchronizer sleeve to the fully engaged position with the engaging gear of the target gear position; this process occurs during Figure 2 the time period of t4 - t5 in

[0055] Specifically, Step 5 includes:

[0056] Step 5.1: After the speed adjustment is completed, first move the synchronizer sleeve accurately to the position where it starts to engage with the engaging gear of the target gear position by means of speed control; accurately adjust the linear axial movement of the synchronizer sleeve by means of speed control to achieve a smooth meshing transition between the power transmission teeth, thereby greatly reducing the torque mutation phenomenon caused by gear shifting and effectively improving the gear shifting smoothness.

[0057] Preferably, the axial moving speed of the engaging sleeve is v, where 0.1mm / 2ms ≤ v ≤ 0.15mm / 2ms.

[0058] Step 5.2: Then, the engaging sleeve is quickly pushed to a position fully meshed with the target gear of the target gear position by means of displacement control; when performing displacement control, the moving speed of the engaging sleeve is much greater than that during speed control. By means of displacement control, the engaging sleeve can be quickly moved to a position fully meshed with the target gear of the target gear position, thereby reducing the shifting time and improving the shifting efficiency.

[0059] Step 6: Finally, the drive motor torque is restored according to the current vehicle requirements to complete the 2AMT shifting process of the electric drive axle. This process occurs in Figure 2 the time period of t5 - t6.

[0060] Step 7: Determine whether the shifting is successful according to the actual position of the engaging sleeve.

[0061] The actual position of the engaging sleeve is specifically determined by comprehensively judging the current motor speed, output torque value, vehicle speed, and current actual working conditions. This judgment process is a conventional technology and will not be elaborated in the embodiments of the present invention.

[0062] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions or substitutions can still be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. An electric drive axle 2AMT shifting method, characterized in that including: Step 1: First, control the driving motor torque of the electric drive axle to drop to 0; Step 2: Then perform the gear disengaging action to drive the synchronizer sleeve to move to the critical gear disengaging position; Step 3: Then adjust the speed of the driving motor according to the rotational speed required for the target gear, so that the rotational speed difference between the synchronizer sleeve and the engaging gear of the target gear is r, where 0 < r ≤ 15 r / min; at the same time, continue to move the synchronizer sleeve to the critical gear engaging position of the target gear; Step 4: After the speed adjustment is completed, move the synchronizer sleeve to the fully engaged position with the engaging gear of the target gear; Step 5: Finally, restore the driving motor torque according to the current vehicle demand to complete the 2AMT shifting process of the electric drive axle.

2. The electric drive axle 2AMT shifting method according to claim 1, wherein In the said Step 3, the synchronizer sleeve is moved to the critical gear engaging position of the target gear by means of displacement control.

3. The electric drive axle 2AMT shifting method according to claim 1, characterized in that The said Step 4 includes: Step 4.1: After the speed adjustment is completed, first move the synchronizer sleeve accurately to the position where it starts to engage with the engaging gear of the target gear by means of speed control; Step 4.2: Then quickly push the synchronizer sleeve to the fully engaged position with the engaging gear of the target gear by means of displacement control.

4. The electric drive axle 2AMT shifting method according to claim 3, characterized in that, In the said Step 4.1: When moving the synchronizer sleeve by means of speed control, the axial moving speed of the synchronizer sleeve is v, and 0.1 mm / 2 ms ≤ v ≤ 0.15 mm / 2 ms.

5. The electric drive bridge 2AMT shifting method according to claim 1, characterized in that, In the said Step 2, the calculation process of the critical gear disengaging position is as follows: Step 2.1: First, engage a certain gear, that is, the synchronizer sleeve engages with any one of the first gear driving gear or the second gear driving gear, the driving motor runs at a fixed speed, after the shifting shaft speed is stable, the synchronizer sleeve moves towards the neutral gear direction at the current fixed speed to disengage the gear, and record the shifting shaft speed during the movement of the synchronizer sleeve; Step 2.2: When the shifting shaft speed starts to drop, the synchronizer sleeve stops moving, record the position of the synchronizer sleeve at the current moment, and observe whether the shifting shaft speed keeps dropping to 0; Step 2.3: If the shifting shaft speed continues to drop to 0, repeat the above steps 3 times, and record the position of the synchronizer sleeve when the shifting shaft speed starts to drop, and calculate the average value of the 3 times to obtain the critical gear disengaging position; Step 2.4: If the shifting shaft speed stops dropping and maintains a fixed speed before dropping to 0, then make the synchronizer sleeve continue to move towards the neutral gear direction at a fixed speed, when the shifting shaft speed starts to drop again, the synchronizer sleeve stops moving, record the position of the synchronizer sleeve at the current moment, and observe whether the shifting shaft speed keeps dropping to 0; Step 2.5: If so, repeat Steps 2.1 to 2.4 to obtain the critical gear disengaging position.

6. The electric drive axle 2AMT shifting method according to claim 1, wherein The critical gear engaging position = the critical gear disengaging position when changing to the opposite gear - the safety margin; the safety margin is a, where 0 ≤ a ≤ 2 mm.

7. A shift execution structure for performing the electric drive bridge 2AMT shift method according to any one of claims 1 to 6, characterized in that, including: Shift shaft, first-gear transmission gear, second-gear transmission gear, spline hub and coupling sleeve; the first-gear transmission gear, second-gear transmission gear and spline hub are all sleeved on the shift shaft; a sliding component is arranged between the first-gear transmission gear, second-gear transmission gear and the shift shaft, and the spline hub is connected to the shift shaft through internal and external splines; the coupling sleeve is sleeved outside the spline hub through internal splines and can achieve axial movement under the action of an external shift power source.

8. The 2AMT shift execution structure of the electric drive bridge according to claim 7, wherein, The external shift power source is electric or hydraulic actuated.

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