A bidirectional mechanical overrunning permanent magnet two-speed transmission and a shifting method thereof

Abstract

The invention relates to a bidirectional mechanical overrunning permanent magnet two-speed transmission and a shifting method thereof, wherein the clutch comprises a transmission housing, a driving mechanism, a magnetic field modulation gear transmission mechanism, a transmission mechanism connecting member, a shift synchronizer and a clutch; the invention uses a single-stage coaxial magnetic field modulation gear as a transmission mechanism, thereby reducing the friction energy loss of the transmission and lowering the operating vibration and noise; the clutch selectively connects the high-speed shaft of the transmission mechanism with the power output shaft, and the shift synchronizer with a bidirectional mechanical overrunning function is connected with the low-speed shaft and the output shaft of the transmission mechanism; after the clutch is engaged, the shift synchronizer automatically overruns, thereby realizing shifting without power interruption, and the shifting process is smooth and impact-free; the coaxial arrangement method is adopted, thereby improving the compactness of the structure, the modularization degree of the shifting mechanism is high, and the shifting operation is simple.

Description

Technical Field

[0001] The present invention relates to the technical field of electric vehicle transmissions, and in particular to a bidirectional mechanical overrunning permanent magnet two-speed transmission and a shifting method thereof. Background Art

[0002] With the continuous development of human science and technology and the continuous improvement of industrial level, the environmental problems caused by the large-scale emission of greenhouse gases have become increasingly prominent. In order to reduce carbon emissions, achieve carbon neutrality goals, and alleviate the ecological problems caused by the large-scale use of fossil energy, countries around the world have begun to vigorously develop electric vehicles. Electric vehicles are mainly composed of power battery systems, drive systems, and vehicle control systems. Since electric vehicle motors have large starting torque and a wide speed regulation range, the current electric vehicle drive system adopts a single-stage reducer with an electric motor structure. However, under a single-stage reducer, in order to achieve a higher vehicle speed, the single-stage reducer has a small reduction ratio, which results in a larger motor working torque and a higher output current, and does not achieve the optimal working efficiency, and consumes power faster. Therefore, in order to enable the motor to provide higher starting, climbing, and speed-up torque in the constant torque range, and also provide a higher driving speed in the constant power range, it is necessary to design and develop a two-speed transmission that takes into account the economy and power of electric vehicles.

[0003] With the emergence of more and more pure electric vehicles, people's requirements for electric vehicles are no longer just satisfied with driving comfort and economy, but also hope that electric vehicles have power comparable to traditional fuel vehicles. This poses a challenge to the performance of the two-speed transmission of electric vehicles. By searching the existing related technologies, it is known that Chinese patent CN209262227 discloses a two-speed transmission shifting system. It includes a transmission front housing, a transmission rear housing, a shift fork shaft and a shift fork. In this scheme, the power source needs to be disconnected when the shift fork is used for shifting, resulting in shifting setbacks during driving, affecting the driving experience. Chinese patent CN112343981 discloses a two-speed transmission without power interruption for pure electric vehicles. It includes an input shaft, an intermediate shaft, an output shaft, a first gear driving gear, a second gear driving gear, an auxiliary gear driving gear and a clutch arranged on the input shaft in sequence, a main reducer driving gear, a first gear driven gear, a synchronizer, a second gear driven gear and an auxiliary gear driven gear arranged on the intermediate shaft in sequence, and a main reducer driven gear and a differential arranged on the output shaft in sequence. In this scheme, auxiliary gears and synchronizers are used to achieve non-power interruption shifting. However, in this solution, the parallel shaft arrangement and the setting of the auxiliary gear position lead to the oversized reducer and complex structure. At the same time, the synchronizer shifting is adopted, and the shifting impact problem is obvious. Chinese patent CN110748615 discloses a two-speed transmission shifting device and a shifting method thereof. It includes a gear seat, a high-speed driving gear, a high-speed driven gear, a low-speed driving gear, a low-speed driven gear, an input shaft and an output shaft, a clutch shifting mechanism and a reverse gear mechanism. This solution realizes forward power-free interruption shifting, but the reverse gear is realized by using a toothed sliding sleeve, which increases the complexity of the mechanism and there is a noise problem of reverse gear hitting. Chinese patent CN107763153 discloses a planetary gear type two-speed transmission for electric vehicles. It includes a planetary gear system, a first clutch device, and a second clutch device. This solution switches gears by cooperating with a planetary gear mechanism with two clutch mechanisms arranged separately, but due to the complex structure of the planetary gear mechanism, the two clutches are difficult to control with each other, and the shifting smoothness is poor, which affects the driving comfort. Chinese patent CN105526318 discloses an electric drive system based on a two-speed transmission, including a drive mechanism, a planetary gear system, a brake, a clutch, a one-way overrunning clutch, and an output shaft. This solution uses a clutch in conjunction with a one-way overrunning clutch to switch gears, achieving uninterrupted power switching and good gear shifting smoothness. However, due to the working characteristics of the one-way overrunning clutch, it is necessary to use a brake to achieve reverse gear, and the clutch is also required to be on and off to achieve brake energy recovery in low gears, which is difficult to control and the clutch is prone to wear, affecting the service life of the gearbox. Chinese patent CN106763619 discloses a two-speed transmission for electric vehicles, including an input shaft assembly, an intermediate shaft assembly, an output shaft assembly, and a box assembly.This scheme adopts a layout scheme of placing two sets of gears on parallel shafts and using two clutches to achieve gear shifting, which can overcome the problem of power interruption, but due to the large number of gears, the mass of the gearbox is large. In addition, there is friction and drag when switching between the two clutches, which increases the shifting viscosity and energy loss, affecting the driving comfort of the vehicle.

[0004] In summary, the problems of gear shift power interruption, noise, gear shift sticking, impact, and complex control of brake energy recovery are common in existing two-speed gearboxes. In addition, the increased structural complexity brought about by overcoming various problems has reduced the economy and reliability of the two-speed gearbox. Therefore, it is an urgent problem that high-performance two-speed gearboxes need to solve to achieve smooth gear shifting without power interruption, fast response to brake energy recovery, and reduce vehicle noise caused by the transmission with a relatively simple and reliable structure and control method. Summary of the invention

[0005] In view of the above problems, the purpose of the present invention is to provide a bidirectional mechanical overriding permanent magnet two-speed transmission and a shifting method thereof, which overcomes the problems of power interruption, impact, noise, etc. of the existing two-speed transmission during shifting based on the principle of magnetic field modulation, and makes the overall structure more compact and the shifting control simpler.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A bidirectional mechanical overrunning permanent magnet two-speed transmission proposed in the present invention comprises a transmission housing, a drive mechanism, a magnetic field modulation gear speed change mechanism, a speed change mechanism connecting member, a shift synchronizer and a clutch; the drive mechanism, the magnetic field modulation gear speed change mechanism, the speed change mechanism connecting member, the shift synchronizer and the clutch are all arranged inside the transmission housing;

[0008] The driving mechanism comprises a driving motor, an input shaft, an intermediate shaft and an output shaft; the input shaft, the intermediate shaft and the output shaft are connected to the transmission housing in sequence through bearings; the output shaft is fixedly connected to the electric vehicle main reducer; the driving motor main shaft is fixedly connected to the input shaft; the driving motor is fixedly connected to the transmission housing;

[0009] The shift synchronizer comprises a second connecting member, a common spline shaft section, a first end face ratchet plate, a second end face ratchet plate, an inner ratchet wheel, an inner bevel gear, a spiral spline shaft section, an outer bevel gear, a first return spring, a pawl mounting section, an axially movable member and a second return spring; the second connecting member is coaxially fixedly connected to the common spline shaft section; the first end face ratchet plate is axially slidably connected to the common spline shaft section through the inner straight spline on the ratchet plate; the first end face ratchet plate can slide to the right along the common spline shaft section to form a one-way contact connection with the second end face ratchet plate; the second end face ratchet plate is coaxially fixedly connected to the inner ratchet wheel; the second end face ratchet plate is coaxially fixedly connected to the inner bevel gear; the The helical spline shaft section is coaxially fixedly connected with the common spline shaft section; the helical spline shaft section is axially rotationally slidably connected with the external helical gear through the helical spline; the ratchet mounting section is axially rotationally slidably connected with the helical spline shaft section through the helical spline; the first return spring is coaxially arranged with the helical spline shaft section, the left side of which contacts the right end face of the external helical gear, and the right side contacts the left end face of the right shoulder of the helical spline shaft section; the lower end of the axially movable member is slidably connected with the first end face ratchet disk, and the upper end is slidably connected with the transmission housing; the second return spring is coaxially arranged with the common spline section, the left side of which contacts the right side of the second connecting member, and the right side contacts the left end face of the first end face ratchet disk;

[0010] The pawl mounting section includes an annular mounting frame, a pawl, an inertial actuating member and a tension spring; the annular mounting frame is coaxially arranged with the inner ratchet and can rotate relatively; the right side of the annular mounting frame is fixedly connected to the left side of the inner bevel gear; the pawl is hinged to the hinge column installed on the annular mounting frame through an intermediate hinge hole, and the rotation range of the pawl is limited by a limit column installed on the annular mounting frame; the inertial actuating member is hinged to another hinge column installed on the annular mounting frame through the intermediate hinge hole; a limit column fixed to the annular mounting frame is also provided on the right side of the inertial braking member; the front end of the tension spring is fixedly connected to the rear end of the inertial braking member, and the rear end is hinged to the third hinge column installed on the annular mounting frame; the rear end of the pawl is in contact and connected with the head of the inertial actuating member;

[0011] The clutch is fixedly connected to the output shaft and can be selectively fixedly connected to or disconnected from the intermediate shaft; the clutch is fixedly connected to the internal helical gear of the shift synchronizer;

[0012] The magnetic field modulation gear speed change mechanism is coaxially arranged between the input shaft and the intermediate shaft;

[0013] The common spline shaft section of the shift synchronizer is connected to the magnetic field modulation gear speed change mechanism through a speed change mechanism connecting piece.

[0014] Furthermore, the magnetic field modulation gear speed change mechanism includes an inner magnetic wheel with M pairs of magnetic poles, an outer magnetic wheel with N pairs of magnetic poles and a magnetic adjustment ring; the magnetic adjustment ring is arranged between the inner magnetic wheel and the outer magnetic wheel; the number of magnetic pole pairs satisfies that M is less than N; the outer magnetic wheel or the inner magnetic wheel is fixedly connected to the transmission housing; the input shaft is coaxially fixedly connected to the inner magnetic wheel or the outer magnetic wheel; the intermediate shaft is coaxially fixedly connected to the rotating component fixedly connected to the input shaft in the magnetic field modulation gear speed change mechanism; the magnetic adjustment ring is connected to the ordinary spline shaft section of the shift synchronizer.

[0015] Furthermore, the magnetic field modulation gear speed change mechanism adopts axial magnetization or radial magnetization.

[0016] Furthermore, the magnetic field modulation gear speed change mechanism adopts radial magnetization; the input shaft is fixedly connected to the outer magnetic wheel; and the inner magnetic wheel is fixedly connected to the transmission housing.

[0017] Furthermore, the magnetic field modulation gear speed change mechanism adopts axial magnetization; the input shaft is fixedly connected to the inner magnetic wheel; and the outer magnetic wheel is fixedly connected to the transmission housing.

[0018] A shifting method for a bidirectional mechanical overrunning permanent magnet two-speed transmission is used for switching forward speed and reversing of a vehicle and realizing braking energy recovery during braking; the method comprises the following steps:

[0019] S1: The clutch is disconnected from the intermediate shaft, and the axially movable member moves to the left, causing the first end face ratchet plate to be disconnected from the second end face ratchet plate, and the motor rotates forward. When the speed reaches a certain value, the inertial actuating member in the shift synchronizer is thrown out under the action of the inertial force, and the tail end is contacted with the limit column, so that the pawl is no longer limited. The pawl is thrown out under the action of the inertial force and contacts with the inner ratchet wheel; at this time, the outer bevel gear is meshed with the inner bevel gear under the push of the spiral spline, and the vehicle starts to move forward. At this time, the axially movable member is in an unloaded free state, and the first end face ratchet plate is meshed with the second end face ratchet plate under the action of the spring; at this point, the vehicle is engaged in the first forward gear, and the transmission reduction ratio is M+N / M or M+N / N; if the vehicle is braked in this state, the motor stops outputting torque, and acts as a generator to receive the torque transmitted from the output end through the second end face ratchet, the first end face ratchet and the transmission, so as to realize braking energy recovery;

[0020] S2: When the electric vehicle is driving in the first gear, if the speed reaches the requirement for shifting up, the axial moving member first moves to the left, disconnecting the first end face ratchet plate from the second end face ratchet plate, and the clutch begins to engage with the intermediate shaft. The internal bevel gear of the shift synchronizer pushes the external bevel gear to perform a separation movement along the spiral spline. Finally, the clutch is fixedly connected to the intermediate shaft, the internal bevel gear is disconnected from the external bevel gear, and the vehicle shifts up to the second gear, with a transmission speed ratio of 1. At this time, if the vehicle is braked, the motor stops outputting torque, and the generator receives the torque transmitted from the output end through the clutch to achieve braking energy recovery.

[0021] S3: During normal driving of the electric vehicle in the second gear, when the vehicle speed drops to the speed threshold of the first gear, the clutch is disconnected from the intermediate shaft, and the motor speed gradually increases to a state where the speeds of the inner pawl, the pawl mounting section and the inner ratchet of the shift synchronizer are equal, causing the outer bevel teeth to mesh with the inner bevel teeth under the push of the spiral spline, and the axially movable member is in an unloaded free state. The first end face ratchet disc is meshed with the second end face ratchet disc under the action of the spring, and the vehicle gear is reduced to the first gear;

[0022] S4: After the electric vehicle has completed parking, the axial moving member moves to the left, disconnecting the first end face ratchet plate from the second end face ratchet plate, disconnecting the clutch from the intermediate shaft, and the ratchet pawl in the shift synchronizer is in an un-wedged state. At this time, no matter how the vehicle is pushed by the outside world, the torque cannot be transferred to the motor, and the electric vehicle is in a neutral state;

[0023] S5: The clutch is disconnected from the intermediate shaft, the axially movable member is in a free state, and the first end face ratchet plate is engaged with the second end face ratchet plate under the action of the spring; the motor rotates in the reverse direction, the vehicle is in reverse gear, and the transmission ratio is M+N / M or M+N / N.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The present invention utilizes magnetic field modulation gears as the transmission speed transmission mechanism, reduces the shifting shock and transmission noise through non-contact transmission of torque, and improves the comfort of the driver.

[0026] 2. The present invention adopts an automatic shift synchronizer in conjunction with a clutch as a shift actuator, thereby achieving shifting without power interruption and improving the driving stability of the vehicle.

[0027] 3. The present invention switches the working mode of the gear shift synchronizer to realize braking power recovery when the vehicle is running at a low speed, and the control is simple. When the vehicle is running at a high speed, the drag torque of the low-speed magnetic wheel is reduced, and the energy loss is small.

[0028] 4. The present invention uses the meshing of the end face ratchets to realize the reverse gear function, which simplifies the transmission structure and improves the compactness of the transmission.

[0029] 5. The present invention adopts a non-contact magnetic field modulation gear, which can reduce the impact of power output end vibration on the transmission system; no lubrication is required during operation, which improves the operating stability of the two-speed transmission under harsh conditions and saves transmission maintenance expenses. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a schematic structural diagram of a two-speed transmission in Embodiment 1 of the present invention;

[0031] Figure 2 1 is a schematic structural diagram of a two-speed transmission in the first forward gear working state in Embodiment 1 of the present invention;

[0032] Figure 3 1 is a schematic structural diagram of a two-speed transmission in a forward second gear working state in Embodiment 1 of the present invention;

[0033] Figure 4 is a schematic structural diagram of a two-speed transmission in reverse gear working state in embodiment 1 of the present invention;

[0034] Figure 5 This is a schematic diagram of the structure of a two-speed transmission in neutral working state in Embodiment 1 of the present invention;

[0035] Figure 6 is a schematic structural diagram of a two-speed transmission in Embodiment 2 of the present invention;

[0036] Figure 7 2 is a schematic structural diagram of a two-speed transmission in a forward first gear working state in Embodiment 2 of the present invention;

[0037] Figure 8 2 is a schematic structural diagram of a two-speed transmission in a forward second gear working state in Embodiment 2 of the present invention;

[0038] Fig. 9 is a schematic structural diagram of a two-speed transmission in reverse gear working state in embodiment 2 of the present invention;

[0039] Fig.10 is a schematic structural diagram of a two-speed transmission in a neutral working state in Embodiment 2 of the present invention;

[0040] Fig.11 It is a structural schematic diagram of the radial magnetic field modulation gear speed change mechanism in the present invention;

[0041] Fig.12 It is a structural schematic diagram of the axial magnetic field modulation gear speed change mechanism in the present invention;

[0042] Fig.13is an enlarged structural schematic diagram of the interior of the shift synchronizer in the present invention;

[0043] Fig.14 yes Fig.13 Schematic diagram of the structure of the middle pawl installation section. DETAILED DESCRIPTION

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0045] It should be noted that, in the description of the present invention, the terms "up", "down", "top", "bottom", "one side", "the other side", "left", "right", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not mean that the device or element must have a specific orientation, be constructed and operated in a specific orientation.

[0046] A bidirectional mechanical overrunning permanent magnet two-speed transmission proposed in the present invention comprises a shift synchronizer 7, a clutch 9, a transmission housing 12, a drive mechanism, a magnetic field modulation gear speed change mechanism and a speed change mechanism connecting member; the drive mechanism, the magnetic field modulation gear speed change mechanism, the speed change mechanism connecting member, the shift synchronizer 7 and the clutch 9 are all arranged inside the transmission housing 12.

[0047] The driving mechanism includes a driving motor 1, an input shaft 2, an intermediate shaft 8 and an output shaft 10; the input shaft 2, the intermediate shaft 8 and the output shaft 10 are connected to the transmission housing 12 in sequence through bearings; the output shaft 10 is fixedly connected to the electric vehicle main reducer 11; the main shaft of the driving motor 1 is fixedly connected to the input shaft 2; the driving motor 1 is fixedly connected to the transmission housing 12.

[0048] As attached Fig.13 and 14As shown, the shift synchronizer 7 includes a second connecting member 701, a common spline shaft section 702, a first end face ratchet plate 703, a second end face ratchet plate 704, an inner ratchet wheel 705, an inner bevel gear 706, a spiral spline shaft section 707, an outer bevel gear 708, a first return spring 709, a pawl mounting section 710, an axial moving member 711 and a second return spring 712; the second connecting member 701 is coaxially fixedly connected with the common spline shaft section 702; the first end face ratchet plate 703 is axially slidably connected with the common spline shaft section 702 through the inner straight spline on the ratchet plate; the first end face ratchet plate 703 can slide to the right along the common spline shaft section 702 to form a one-way contact connection with the second end face ratchet plate 704; the second end face ratchet plate 704 is coaxially fixedly connected with the inner ratchet wheel 705; the second end face ratchet plate 703 is axially connected with the inner bevel gear 706; the second end face ratchet plate 704 is coaxially fixedly connected with the inner ratchet wheel 705; the second end face ratchet plate 703 is axially connected with the inner bevel gear 706. 706 is coaxially fixedly connected; the helical spline shaft section 707 is coaxially fixedly connected with the ordinary spline shaft section 702; the helical spline shaft section 707 is axially rotated and slidably connected with the external bevel gear 708 through the helical spline; the pawl mounting section 710 is axially rotated and slidably connected with the helical spline shaft section 707 through the helical spline; the first return spring 709 is coaxially arranged with the helical spline shaft section 707, the left side of which contacts with the right end face of the external bevel gear 708, and the right side contacts with the left end face of the right shoulder of the helical spline shaft section 707; the lower end of the axial moving member 711 is slidably connected with the first end face ratchet disk 703, and the upper end is slidably connected with the transmission housing; the second return spring 712 is coaxially arranged with the ordinary spline section 702, the left side of which contacts with the right side of the second connecting member 701, and the right side contacts with the left end face of the first end face ratchet disk 703.

[0049] The pawl mounting section 710 includes an annular mounting frame 7101, a pawl 7102, an inertial actuating member 7103 and a tension spring 7104; the annular mounting frame 7101 is coaxially arranged with the inner ratchet 705 and can rotate relatively; the right side of the annular mounting frame 7101 is fixedly connected to the left side of the inner bevel gear 706; the pawl 7102 is hinged to the hinge column on one side of the annular mounting frame 7101 through the middle hinge hole, and the pawl is limited by the limit column installed on the annular mounting frame 7101 The inertial actuating member 7103 is hinged to the hinge column installed on the other side of the annular mounting frame through the middle hinge hole; a limiting column fixed on the annular mounting frame 7101 is also provided on the right side of the inertial braking member 7103; the front end of the tension spring 7104 is fixedly connected to the rear end of the inertial braking member 7103, and the rear end is hinged to the third hinge column installed on the annular mounting frame 7101; the rear end of the pawl 7102 is in contact and connected with the head of the inertial actuating member 7103.

[0050] One side of the clutch 9 is fixedly connected to the output shaft and can be selectively fixedly connected or disconnected with the intermediate shaft 8, and the other side is fixedly connected to the internal bevel gear 706 of the shift synchronizer 7; the magnetic field modulation gear speed change mechanism is coaxially arranged between the input shaft 2 and the intermediate shaft 8.

[0051] As attached Fig.11 and 12 As shown, the magnetic field modulation gear speed change mechanism includes an inner magnetic wheel 3 with M pairs of magnetic poles, an outer magnetic wheel 5 with N pairs of magnetic poles and a magnetic adjustment ring 4; the magnetic adjustment ring 4 is coaxially arranged between the inner magnetic wheel 3 and the outer magnetic wheel 5; the number of magnetic pole pairs satisfies that M is less than N; the outer magnetic wheel 5 or the inner magnetic wheel 3 is fixedly connected to the transmission housing 12; the input shaft 2 is coaxially fixedly connected to the inner magnetic wheel 3 or the outer magnetic wheel 5; the intermediate shaft 8 is coaxially fixedly connected to the rotating member fixedly connected to the input shaft 2 in the magnetic field modulation gear speed change mechanism; the magnetic adjustment ring 4 is connected to the ordinary spline shaft section 702 of the shift synchronizer 7.

[0052] The magnetic field modulation gear speed change mechanism is an axially magnetized magnetic field modulation gear or a radially magnetized magnetic field modulation gear.

[0053] When the magnetic field modulation gear speed change mechanism adopts the radially magnetized magnetic field modulation gear, the input shaft 2 is fixedly connected to the outer magnetic wheel 5 , and the inner magnetic wheel 3 is fixedly connected to the transmission housing 12 .

[0054] When the magnetic field modulation gear speed change mechanism adopts the axially magnetized magnetic field modulation gear, the input shaft 2 is fixedly connected to the inner magnetic wheel 3 ; the outer magnetic wheel 5 is fixedly connected to the transmission housing 12 .

[0055] A shifting method for a bidirectional mechanical overrunning permanent magnet two-speed transmission is used for switching forward speed and reversing of a vehicle and realizing braking energy recovery during braking; the method comprises the following steps:

[0056] S1: The clutch 9 is disconnected from the intermediate shaft 8, and the axial moving member 711 moves to the left, so that the first end face ratchet plate 703 is disconnected from the second end face ratchet plate 704, and the driving motor 1 rotates forward. When the speed reaches a certain value, the inertial actuating member 7103 in the shift synchronizer is thrown out by the inertial force, and the tail end is contacted with the limit column, so that the pawl 7102 is no longer limited. The pawl 7102 is thrown out by the inertial force and contacts with the inner ratchet 705; at this time, the outer bevel gear 708 is pushed by the helical spline The first end face ratchet disc 703 meshes with the second end face ratchet disc 704 under the action of the spring. At this point, the vehicle is in forward gear 1, and the transmission reduction ratio is M+N / M or M+N / N. If the vehicle is braked in this state, the drive motor 1 stops outputting torque and acts as a generator to receive torque transmitted from the output end through the second end face ratchet disc, the first end face ratchet disc and the transmission, thereby realizing braking energy recovery.

[0057] S2: When the electric vehicle is driving in the first gear, if the speed reaches the requirement for shifting up, the axial moving member 711 first moves to the left, so that the first end face ratchet plate is disconnected from the second end face ratchet plate, the clutch 9 starts to engage with the intermediate shaft 8, and the internal bevel gear 706 of the shift synchronizer pushes the external bevel gear 708 to perform a separation movement along the spiral spline. Finally, the clutch 9 is fixedly connected to the intermediate shaft 8, the internal bevel gear 706 is disconnected from the external bevel gear 708, the vehicle shifts up to the second gear, and the transmission speed ratio is 1; at this time, if the vehicle is braked, the drive motor 1 stops outputting torque, and the generator receives the torque transmitted from the output end through the clutch 9 to achieve braking energy recovery;

[0058] S3: During normal driving of the electric vehicle in the second gear, when the vehicle speed drops to the speed threshold of the first gear, the clutch 9 is disconnected from the intermediate shaft 8, and the speed of the drive motor 1 is gradually increased to a state where the speeds of the inner ratchet 7102 of the shift synchronizer and the inner ratchet 705 are equal, so that the outer bevel gear 708 is meshed with the inner bevel gear 706 under the push of the helical spline, the axial moving member 711 is in an unloaded free state, and the first end face ratchet plate 703 is meshed with the second end face ratchet plate 704 under the action of the spring, and the vehicle gear is reduced to the first gear;

[0059] S4: After the electric vehicle has completed parking, the axial moving member 711 moves to the left, disconnecting the first end face ratchet plate 703 from the second end face ratchet plate 704, disconnecting the clutch 9 from the intermediate shaft 8, and the ratchet pawl 7102 in the shift synchronizer is in an un-wedged state. At this time, no matter how the vehicle is pushed by the outside world, the torque cannot be transferred to the drive motor 1, and the electric vehicle is in a neutral state;

[0060] S5: The clutch 9 is disconnected from the intermediate shaft 8, the axially movable member 711 is in a free state, and the first end face ratchet plate is engaged with the second end face ratchet plate under the action of the spring; the drive motor 1 rotates in the reverse direction, the vehicle is in the reverse gear state, and the transmission speed ratio is M+N / M or M+N / N.

[0061] The present invention is further described below by specific embodiments:

[0062] Embodiment 1:

[0063] As attached Figure 1 As shown, a bidirectional mechanical overrunning permanent magnet two-speed transmission includes a transmission housing 12, a drive mechanism, a magnetic field modulation gear transmission mechanism, a shift synchronizer 7, a transmission mechanism connecting member 6 and a clutch 9; the drive mechanism, the magnetic field modulation gear transmission mechanism, the shift synchronizer 7 and the clutch 9 are all arranged in the transmission housing 12.

[0064] The driving mechanism includes a driving motor 1, an input shaft 2, an intermediate shaft 8 and an output shaft 10; the input shaft 2, the intermediate shaft 8 and the output shaft 10 are connected to the transmission housing in sequence through bearings, the output shaft 10 is fixedly connected to the electric vehicle main reducer 11, the driving motor 1 is fixedly connected to the input shaft 2, and the driving motor 1 is fixedly connected to the transmission housing 12.

[0065] The magnetic field modulation gear speed change mechanism includes an inner magnetic wheel 3 with M pairs of magnetic poles, an outer magnetic wheel 5 with N pairs of magnetic poles and a magnetic modulation ring 4; the number of magnetic pole pairs satisfies that M is less than N, and the outer magnetic wheel 5 is fixedly connected to the transmission housing 12; the input shaft 2 is fixedly connected to the inner magnetic wheel 3, and the intermediate shaft 8 is fixedly connected to the inner magnetic wheel 3; the shift synchronizer 7 is fixedly connected to the magnetic modulation ring 4 through the second connecting member 701 and the speed change mechanism connecting member 6; in this embodiment, the magnetic field modulation gear speed change mechanism is an axially magnetized magnetic field modulation gear.

[0066] The shift synchronizer 7 includes a second connecting member 701, a common spline shaft section 702, a first end face ratchet plate 703, a second end face ratchet plate 704, an inner ratchet wheel 705, an inner bevel gear 706, a spiral spline shaft section 707, an outer bevel gear 708, a first return spring 709, a pawl mounting section 710, an axial moving member 711 and a second return spring 712.

[0067] The second connecting member 701 is coaxially fixedly connected with the common spline shaft section 702, the first end face ratchet plate 703 is axially slidably connected with the common spline shaft section 702 through the inner straight spline on the ratchet plate, the first ratchet plate can slide rightward along the common spline shaft section 702 to form a one-way contact connection with the second end face ratchet plate 704, the second end face ratchet plate 704 is coaxially fixedly connected with the inner ratchet wheel 705, the second end face ratchet plate 704 is coaxially fixedly connected with the inner bevel gear 706, the helical spline shaft section 707 is coaxially fixedly connected with the common spline shaft section 702, the helical spline The shaft section 707 is connected to the external bevel gear 708 in an axial rotational sliding manner through a spiral spline, the ratchet mounting section 710 is connected to the spiral spline shaft section 707 in an axial rotational sliding manner through a spiral spline, the first return spring 709 is coaxially arranged with the spiral spline shaft section 707, the left side contacts the right end face of the external bevel gear 708, the right side contacts the left end face of the right shoulder of the spiral spline shaft end, the lower end of the axial moving member 711 is connected to the groove on the first end face ratchet disk 703 in a sliding manner, and the upper end of the axial moving member 711 is connected to the horizontal upper hole on the transmission housing in a sliding manner. The second return spring 712 is coaxially arranged with the common spline section, the left side of the second return spring 712 contacts the right side of the connecting member, and the right side of the second return spring 712 contacts the right end face of the first end face ratchet disk 703.

[0068] The pawl mounting section 710 includes an annular mounting frame 7101, a pawl 7102, an inertial actuating member 7103 and a tension spring 7104; the annular mounting frame 7101 is coaxially arranged with the inner ratchet 705 and can rotate relatively; the right side of the annular mounting frame 7101 is fixedly connected to the left side of the inner bevel gear 706; the pawl 7102 is hinged to the first hinge column mounted on the annular mounting frame 7101 through the middle hinge hole, and is limited by the limit column on the annular mounting frame 7101 The inertial actuating member 7103 is hinged to the second hinged column installed on the annular mounting frame 7101 through the middle hinge hole; a limiting column fixed to the annular mounting frame 7101 is provided on the right side of the inertial braking member 7103; the front end of the tension spring 7104 is fixedly connected to the rear end of the inertial braking member 7103, and the rear end is hinged to the third hinged column installed on the annular mounting frame 7101; the rear end of the pawl 7102 is in contact with the head of 7103.

[0069] The clutch 9 is fixedly connected to the output shaft 10 , and the clutch 9 can be selectively fixedly connected to or disconnected from the intermediate shaft 8 . The left end surface of the clutch 9 is fixedly connected to the right end surface of the internal bevel gear 706 of the shift synchronizer 7 .

[0070] Looking from right to left, the main shaft rotates clockwise as the forward direction.

[0071] As attached Figures 2 to 5 As shown, the shifting operation method and braking energy recovery strategy of embodiment 1 are as follows:

[0072] S1: The clutch 9 is disconnected from the intermediate shaft 8, and the axial moving member 711 moves to the left, causing the first end face ratchet disc 703 to be disconnected from the second end face ratchet disc 704, and the motor 1 rotates forward. When the speed reaches a certain value, the inertia braking member 7103 in the shift synchronizer 7 is in contact with the limit column at the rear end under the action of the inertia force, so that the pawl 7102 is no longer limited. The pawl 7102 is thrown out under the action of the inertia force and contacts the inner ratchet 705. At this time, the outer bevel gear 708 is meshed with the inner bevel gear 706 under the push of the helical spline 707, and the vehicle starts to move forward. At this time, the axial moving member 711 is in an unloaded free state, and the first end face ratchet disc 703 is meshed with the second end face ratchet disc 704 under the action of the second return spring 712. At this point, the vehicle is in forward gear 1, and the transmission reduction ratio is M+N / M.

[0073] If the vehicle is braked in this state, the motor 1 stops outputting torque and acts as a generator 1 to receive feedback torque from the output end through the output shaft 10, the clutch 9, the shift synchronizer 7, the speed change mechanism connecting part 6, the magnetic adjustment ring 4, the inner magnetic wheel 3, and the input shaft 2, thereby realizing braking energy recovery.

[0074] S2: During the driving process of the electric vehicle in the first gear, if the speed reaches the requirement for shifting up, the axial moving member 711 first moves to the left, so that the first end face ratchet plate 703 is disconnected from the second end face ratchet plate 704, the clutch 9 starts to engage with the intermediate shaft 8, and the internal bevel gear 706 in the shift synchronizer 7 pushes the external bevel gear 708 to do a separation movement along the spiral spline 707. Finally, the clutch 9 is fixedly connected to the intermediate shaft 8, the internal bevel gear 706 is disconnected from the external bevel gear 708, the vehicle shifts up to the second gear, and the transmission speed ratio is 1. At this time, if the vehicle is braked, the motor stops outputting torque, and the generator 1 receives the feedback torque from the output end through the output shaft 10, the clutch 9, the intermediate shaft 8, the inner magnetic wheel 3, and the input shaft 2 to achieve braking energy recovery.

[0075] S3: During the normal driving of the electric vehicle in the second gear, when the vehicle speed drops to the speed threshold of the first gear, the clutch 9 is disconnected from the intermediate shaft 8, and the speed of the motor 1 is gradually increased to a state where the speed of the inner ratchet of the shift synchronizer 7 is equal to the speed of the ratchet installation section of the overrunning clutch, so that the outer bevel gear 708 is driven by the helical spline shaft section 707 to mesh with the inner bevel gear 706, the axial moving member 711 is in an unloading free state, and the first end face ratchet plate 703 is engaged with the second end face ratchet plate 704 under the action of the second return spring 712. The vehicle gear is reduced to the first gear.

[0076] S4: After the electric vehicle has completed parking, the axially movable member 711 moves to the left, disconnecting the first end face ratchet plate 703 from the second end face ratchet plate 704, and the clutch 9 from the intermediate shaft 8 is always disconnected. The inner ratchet 705 in the shift synchronizer 7 and the ratchet on the pawl mounting section 710 are in an un-wedged state. At this time, no matter whether the vehicle is pushed forward or reversely by the outside world, the torque cannot be transferred to the motor, and the electric vehicle is in a neutral state.

[0077] S5: The clutch 9 is disconnected from the intermediate shaft 8, the axially movable member 711 is in a free state, and the first end face ratchet plate 703 is engaged with the second end face ratchet plate 704 under the action of the second return spring 712; the motor 1 rotates in the reverse direction, the vehicle is in the reverse gear state, and the transmission speed ratio is M+N / M.

[0078] Embodiment 2:

[0079] As attached Figure 6 As shown, a bidirectional mechanical overrunning permanent magnet two-speed transmission includes a transmission housing 12, a drive mechanism, a magnetic field modulation gear transmission mechanism, a shift synchronizer 7, a connecting member 6, and a clutch 9. The drive mechanism, the magnetic field modulation gear transmission mechanism, the shift synchronizer 7, and the clutch 9 are all arranged in the transmission housing 12.

[0080] The driving mechanism includes a driving motor 1, an input shaft 2, an intermediate shaft 8, and an output shaft 10; the input shaft 2, the intermediate shaft 8, and the output shaft 10 are connected to the transmission housing through bearings, the output shaft 10 is fixedly connected to the electric vehicle main reducer 11, the driving motor 1 is fixedly connected to the input shaft 2, and the driving motor 1 is fixedly connected to the transmission housing 12.

[0081] The magnetic field modulation gear speed change mechanism comprises an inner magnetic wheel 3 with M pairs of magnetic poles, an outer magnetic wheel 5 with N pairs of magnetic poles and a magnetic modulation ring 4; the number of magnetic pole pairs satisfies that M is less than N, the inner magnetic wheel 3 is fixedly connected to the transmission housing 12; the input shaft 2 is fixedly connected to the outer magnetic wheel 5, and the intermediate shaft 8 is fixedly connected to the outer magnetic wheel 5; the shift synchronizer 7 is fixedly connected to the speed change mechanism connector 6 and the magnetic modulation ring 4 through the second connecting member 701. In this embodiment, the magnetic field modulation gear speed change mechanism is a radially magnetized magnetic field modulation gear.

[0082] The shift synchronizer 7 includes a second connecting member 701, a common spline shaft section 702, a first end face ratchet plate 703, a second end face ratchet plate 704, an inner ratchet wheel 705, an inner bevel gear 706, a spiral spline shaft section 707, an outer bevel gear 708, a first return spring 709, a pawl mounting section 710, an axial moving member 711 and a second return spring 712.

[0083] The second connecting member 701 is coaxially fixedly connected with the common spline shaft section 702. The first end face ratchet disc 703 is axially slidably connected with the common spline shaft section 702 through the inner straight spline on the ratchet disc, and the first ratchet disc can slide rightward along the common spline shaft section 702 to form a one-way contact connection with the second end face ratchet disc 704. The second end face ratchet plate 704 is coaxially fixedly connected to the inner ratchet wheel 705, the second end face ratchet plate 704 is coaxially fixedly connected to the inner bevel gear 706, the helical spline shaft section 707 is coaxially fixedly connected to the ordinary spline shaft section 702, the helical spline shaft section 707 is axially rotated and slidably connected with the outer bevel gear 708 through the helical spline, the pawl mounting section 710 is axially rotated and slidably connected with the helical spline shaft section 707 through the helical spline, the first return spring 709 is coaxially arranged with the helical spline shaft section 707, the left side contacts the right end face of the outer bevel gear 708, and the right side contacts the left end face of the right side shoulder of the helical spline shaft end, the lower end of the axially movable member 711 is slidably connected to the groove on the first end face ratchet plate 703, and the upper end of the axially movable member 711 is slidably connected to the horizontal upper hole on the transmission housing. The second return spring 712 is coaxially arranged with the common spline segment, the left side of the second return spring 712 contacts the right side of the connecting member, and the right side of the second return spring 712 contacts the right end surface of the first end surface ratchet disk 703 .

[0084] The pawl mounting section 710 includes an annular mounting frame 7101, a pawl 7102, an inertial actuating member 7103 and a tension spring 7104; the annular mounting frame 7101 is coaxially arranged with the inner ratchet 705 and can rotate relatively. The right side of the annular mounting frame 7101 is fixedly connected to the left side of the inner bevel gear 706. The pawl 7102 is hinged to the first hinge column on the annular mounting frame 7101 through the middle hinge hole, and the rotation range of the pawl 7102 is limited by the limit column on the annular mounting frame 7101. 7103 is hinged to the second hinge column on the annular mounting frame 7101 through the middle hinge hole. The right side of the inertial braking member has a limit column fixed to the annular mounting frame 7101. The front end of the tension spring 7104 is fixedly connected to the rear end of the inertial braking member, and the rear end is hinged to the third hinge column of the annular mounting frame 7101. The rear end of the pawl 7102 is in contact with the head of 7103.

[0085] The clutch 9 is fixedly connected to the output shaft 10 , and the clutch 9 can be selectively fixedly connected to or disconnected from the intermediate shaft 8 ; the clutch 9 is connected to the outer ring of the shift synchronizer 7 .

[0086] As attached Figures 7 to 10 As shown, the shifting operation method and braking energy recovery strategy of embodiment 2 are:

[0087] S1: The clutch 9 is disconnected from the intermediate shaft 8, and the axial moving member 711 moves to the left, causing the first end face ratchet disc 703 to be disconnected from the second end face ratchet disc 704, and the driving motor 1 rotates forward. When the speed reaches a certain value, the inertia braking member 7103 in the shift synchronizer 7 is in contact with the limit column at the rear end under the action of the inertia force, so that the pawl 7102 is no longer limited. The pawl 7102 is thrown out under the action of the inertia force and contacts the inner ratchet 705. At this time, the outer bevel gear 708 is meshed with the inner bevel gear 706 under the push of the helical spline 707, and the vehicle starts to move forward. At this time, the axial moving member 711 is in an unloaded free state, and the first end face ratchet disc 703 is meshed with the second end face ratchet disc 704 under the action of the second return spring 712; at this point, the vehicle is in forward gear 1, and the transmission reduction ratio is M+N / N. If the vehicle is braked in this state, the drive motor 1 stops outputting torque and acts as a generator 1 to receive feedback torque from the output end through the output shaft 10, the clutch 9, the shift synchronizer 7, the speed change mechanism connecting part 6, the magnetic adjustment ring 4, the inner magnetic wheel 3, and the input shaft 2, thereby realizing braking energy recovery.

[0088] S2: During the driving process of the electric vehicle in the first gear, if the speed reaches the requirement for shifting up, the axial moving member 711 first moves to the left, so that the first end face ratchet plate 703 is disconnected from the second end face ratchet plate 704, the clutch 9 starts to engage with the intermediate shaft 8, and the internal bevel gear 706 in the shift synchronizer 7 pushes the external bevel gear 708 to do a separation movement along the spiral spline 707. Finally, the clutch 9 is fixedly connected to the intermediate shaft 8, the internal bevel gear 706 is disconnected from the external bevel gear 708, the vehicle shifts up to the second gear, and the transmission speed ratio is 1. At this time, if the vehicle is braked, the motor stops outputting torque, and the drive motor 1 receives the feedback torque from the output end through the output shaft 10, the clutch 9, the intermediate shaft 8, the inner magnetic wheel 3, and the input shaft 2 to achieve braking energy recovery.

[0089] S3: During the normal driving of the electric vehicle in the second gear, when the vehicle speed drops to the first gear speed threshold, the clutch 9 is disconnected from the intermediate shaft 8, and the speed of the drive motor 1 is gradually increased to a state where the speed of the inner ratchet of the shift synchronizer 7 is equal to the speed of the ratchet installation section of the overrunning clutch, so that the outer bevel gear 708 is meshed with the inner bevel gear 706 under the push of the helical spline 707, the axial moving member 711 is in an unloading free state, and the first end face ratchet plate 703 is meshed with the second end face ratchet plate 704 under the action of the second return spring 712. The vehicle gear is reduced to the first gear.

[0090] S4: After the electric vehicle has completed parking, the axially movable member 711 moves to the left, disconnecting the first end face ratchet plate 703 from the second end face ratchet plate 704, and the clutch 9 from the intermediate shaft 8 is always disconnected. The inner ratchet 705 in the shift synchronizer 7 and the ratchet on the pawl mounting section 710 are in an un-wedged state. At this time, no matter whether the vehicle is pushed forward or reversely by the outside world, the torque cannot be transferred to the motor, and the electric vehicle is in a neutral state.

[0091] S5: The clutch 9 is disconnected from the intermediate shaft 8, the axially movable member 711 is in a free state, and the first end face ratchet plate 703 is engaged with the second end face ratchet plate 704 under the action of the second return spring 712; the drive motor 1 rotates in the reverse direction, the vehicle is in the reverse gear state, and the transmission speed ratio is M+N / N.

[0092] Matters not described in detail in the present invention are known in the art.

[0093] The embodiments described above are merely descriptions of preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A bidirectional mechanical overrunning permanent magnet two-speed transmission, Features: The transmission comprises a transmission housing, a drive mechanism, a magnetic field modulation gear speed change mechanism, a speed change mechanism connecting member, a shift synchronizer and a clutch; the drive mechanism, the magnetic field modulation gear speed change mechanism, the speed change mechanism connecting member, the shift synchronizer and the clutch are all arranged inside the transmission housing; The driving mechanism comprises a driving motor, an input shaft, an intermediate shaft and an output shaft; the input shaft, the intermediate shaft and the output shaft are connected to the transmission housing in sequence through bearings; the output shaft is fixedly connected to the electric vehicle main reducer; the driving motor main shaft is fixedly connected to the input shaft; the driving motor is fixedly connected to the transmission housing; The shift synchronizer comprises a second connecting member, a common spline shaft section, a first end face ratchet plate, a second end face ratchet plate, an inner ratchet wheel, an inner bevel gear, a spiral spline shaft section, an outer bevel gear, a first return spring, a pawl mounting section, an axially movable member and a second return spring; the second connecting member is coaxially fixedly connected to the common spline shaft section; the first end face ratchet plate is axially slidably connected to the common spline shaft section through the inner straight spline on the ratchet plate; the first end face ratchet plate can slide to the right along the common spline shaft section to form a one-way contact connection with the second end face ratchet plate; the second end face ratchet plate is coaxially fixedly connected to the inner ratchet wheel; the second end face ratchet plate is coaxially fixedly connected to the inner bevel gear; the The helical spline shaft section is coaxially fixedly connected with the common spline shaft section; the helical spline shaft section is axially rotationally slidably connected with the external helical gear through the helical spline; the ratchet mounting section is axially rotationally slidably connected with the helical spline shaft section through the helical spline; the first return spring is coaxially arranged with the helical spline shaft section, the left side of which contacts the right end face of the external helical gear, and the right side contacts the left end face of the right shoulder of the helical spline shaft section; the lower end of the axially movable member is slidably connected with the first end face ratchet disk, and the upper end is slidably connected with the transmission housing; the second return spring is coaxially arranged with the common spline section, the left side of which contacts the right side of the second connecting member, and the right side contacts the left end face of the first end face ratchet disk; The pawl mounting section includes an annular mounting frame, a pawl, an inertial actuating member and a tension spring; the annular mounting frame is coaxially arranged with the inner ratchet and can rotate relatively; the right side of the annular mounting frame is fixedly connected to the left side of the inner bevel gear; the pawl is hinged to the hinge column installed on the annular mounting frame through an intermediate hinge hole, and the rotation range of the pawl is limited by a limit column installed on the annular mounting frame; the inertial actuating member is hinged to another hinge column installed on the annular mounting frame through the intermediate hinge hole; a limit column fixed to the annular mounting frame is also provided on the right side of the inertial braking member; the front end of the tension spring is fixedly connected to the rear end of the inertial braking member, and the rear end is hinged to the third hinge column installed on the annular mounting frame; the rear end of the pawl is in contact and connected with the head of the inertial actuating member; The clutch is fixedly connected to the output shaft and can be selectively fixedly connected to or disconnected from the intermediate shaft; the clutch is fixedly connected to the internal helical gear of the shift synchronizer; The magnetic field modulation gear speed change mechanism is coaxially arranged between the input shaft and the intermediate shaft; The common spline shaft section of the shift synchronizer is connected to the magnetic field modulation gear speed change mechanism through a speed change mechanism connecting piece.

2. A bidirectional mechanical overrunning permanent magnet two-speed transmission according to claim 1, Features: The magnetic field modulation gear speed change mechanism includes an inner magnetic wheel with M pairs of magnetic poles, an outer magnetic wheel with N pairs of magnetic poles and a magnetic adjustment ring; the magnetic adjustment ring is arranged between the inner magnetic wheel and the outer magnetic wheel; the number of magnetic pole pairs satisfies that M is less than N; the outer magnetic wheel or the inner magnetic wheel is fixedly connected to the transmission housing; the input shaft is coaxially fixedly connected to the inner magnetic wheel or the outer magnetic wheel; the intermediate shaft is coaxially fixedly connected to the rotating component fixedly connected to the input shaft in the magnetic field modulation gear speed change mechanism; the magnetic adjustment ring is connected to the common spline shaft section of the shift synchronizer.

3. A bidirectional mechanical overrunning permanent magnet two-speed transmission according to claim 2, Features: The magnetic field modulation gear speed change mechanism adopts axial magnetization or radial magnetization.

4. A bidirectional mechanical overrunning permanent magnet two-speed transmission according to claim 3, Features: The magnetic field modulation gear speed change mechanism adopts radial magnetization; the input shaft is fixedly connected to the outer magnetic wheel; and the inner magnetic wheel is fixedly connected to the transmission housing.

5. A bidirectional mechanical overrunning permanent magnet two-speed transmission according to claim 3, Features: The magnetic field modulation gear speed change mechanism adopts axial magnetization; the input shaft is fixedly connected to the inner magnetic wheel; and the outer magnetic wheel is fixedly connected to the transmission housing.

6. A shifting method of a bidirectional mechanical overrunning permanent magnet two-speed transmission according to claim 1, used for switching forward speed and reversing of a vehicle, and realizing braking energy recovery during braking; It is characterized in that The following steps are involved: S1: The clutch is disconnected from the intermediate shaft, and the axial moving member moves to the left, causing the first end face ratchet plate to be disconnected from the second end face ratchet plate, and the motor rotates forward. When the speed reaches a certain value, the inertial actuating member in the shift synchronizer is thrown out under the action of the inertial force, and the tail end is contacted with the limit column, so that the pawl is no longer limited. The pawl is thrown out under the action of the inertial force and contacts with the inner ratchet wheel; At this time, the outer bevel gear meshes with the inner bevel gear under the push of the spiral spline, and the vehicle starts to move forward. At this time, the axial moving member is in an unloaded free state, and the first end face ratchet plate meshes with the second end face ratchet plate under the action of the spring; at this point, the vehicle is engaged in the first forward gear, and the transmission reduction ratio is M+N / M or M+N / N; if the vehicle is braked in this state, the motor stops outputting torque, and acts as a generator to receive the torque transmitted from the output end through the second end face ratchet, the first end face ratchet and the transmission, thereby realizing braking energy recovery; S2: When the electric vehicle is driving in the first gear, if the speed reaches the requirement for shifting up, the axial moving member first moves to the left, disconnecting the first end face ratchet plate from the second end face ratchet plate, and the clutch begins to engage with the intermediate shaft. The internal bevel gear of the shift synchronizer pushes the external bevel gear to perform a separation movement along the spiral spline. Finally, the clutch is fixedly connected to the intermediate shaft, the internal bevel gear is disconnected from the external bevel gear, and the vehicle shifts up to the second gear, and the transmission speed ratio is 1. At this time, if the vehicle is braked, the motor stops outputting torque, and the generator receives the torque transmitted from the output end via the clutch to achieve braking energy recovery; S3: During normal driving of the electric vehicle in the second gear, when the vehicle speed drops to the speed threshold of the first gear, the clutch is disconnected from the intermediate shaft, and the motor speed gradually increases to a state where the speeds of the inner pawl, the pawl mounting section and the inner ratchet of the shift synchronizer are equal, causing the outer bevel teeth to mesh with the inner bevel teeth under the push of the spiral spline, and the axially movable member is in an unloaded free state. The first end face ratchet disc is meshed with the second end face ratchet disc under the action of the spring, and the vehicle gear is reduced to the first gear; S4: After the electric vehicle has completed parking, the axial moving member moves to the left, disconnecting the first end face ratchet plate from the second end face ratchet plate, disconnecting the clutch from the intermediate shaft, and the ratchet pawl in the shift synchronizer is in an un-wedged state. At this time, no matter how the vehicle is pushed by the outside world, the torque cannot be transferred to the motor, and the electric vehicle is in a neutral state; S5: The clutch is disconnected from the intermediate shaft, the axially movable member is in a free state, and the first end face ratchet plate is engaged with the second end face ratchet plate under the action of the spring; the motor rotates in the reverse direction, the vehicle is in reverse gear, and the transmission ratio is M+N / M or M+N / N.

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