Gear shifting system, electric drive axle, engineering vehicle, gear shifting method, device and medium

Abstract

The application discloses a gear shifting system, an electric drive axle, an engineering vehicle, a gear shifting method, a device and a medium, relates to the field of vehicle gear shifting, and aims to improve the reliability of the gear shifting system. The gear shifting system comprises a driving assembly, a rack part, a fork assembly and a gear mechanism. The driving assembly comprises a power source, a power output shaft and a gear output shaft, the power source is drivingly connected with the power output shaft, and the power output shaft is drivingly connected with the gear output shaft. The rack part comprises a body and a rack fixedly connected with the body or integrally formed; the rack is engaged with the gear output shaft; and the body is provided with a mounting through hole. The fork assembly comprises a fork shaft and a fork; the fork shaft is mounted in the mounting through hole and fixedly connected with the mounting through hole; and the fork is fixedly connected with the part of the fork shaft located outside the mounting through hole. The gear mechanism comprises a first-gear gear, a second-gear gear and an engaging sleeve; the engaging sleeve is drivingly connected with the fork; and the inner wall of the engaging sleeve is provided with a first limiting piece and / or a second limiting piece.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of vehicle gear shifting, in particular to a gear shifting system, an electric drive axle, an engineering vehicle, a gear shifting method, a device and a medium. BACKGROUND

[0002] With the rapid development of new energy commercial vehicles and the continuous improvement of drivers' requirements for driving comfort, the gear shifting response speed, gear shifting smoothness and reliability of the electric drive axle gear shifting system are of great concern.

[0003] The inventor found that at least the following problems exist in the prior art: the gear shifting performance of the existing electric drive axle gear shifting system is unreliable, and after gear shifting, the engagement sleeve may be worn out. SUMMARY

[0004] The present application provides a gear shifting system, an electric drive axle, an engineering vehicle, a gear shifting method, a device and a medium to reduce the probability of engagement sleeve wear.

[0005] The present application provides a gear shifting system, comprising:

[0006] A drive assembly comprising a power source, a power output shaft and a gear output shaft, the power source being drivingly connected to the power output shaft, and the power output shaft being drivingly connected to the gear output shaft;

[0007] A rack portion comprising a body and a rack fixedly connected to or integrally formed with the body; the rack is engaged with the gear output shaft; the body is provided with a mounting through hole;

[0008] A shift fork assembly comprising a shift fork shaft and a shift fork; the middle part of the shift fork shaft is mounted in the mounting through hole and fixedly connected thereto; the shift fork is fixedly connected to the part of the shift fork shaft located outside the mounting through hole;

[0009] A gear mechanism comprising a first gear, a second gear and an engagement sleeve; the engagement sleeve is drivingly connected to the shift fork to selectively engage with the first gear or the second gear under the driving of the shift fork to achieve gear shifting; wherein the inner wall of the engagement sleeve is provided with a first limiting piece and / or a second limiting piece to limit the movement limit position of the engagement sleeve.

[0010] In some embodiments, the inner wall of the engagement sleeve is provided with a group of first tapered teeth and a group of second tapered teeth, the first tapered teeth and the second tapered teeth are arranged side by side along the axial direction of the engagement sleeve; at least two adjacent first tapered teeth are provided with the first limiting piece, and at least two adjacent second tapered teeth are provided with the second limiting piece.

[0011] In some embodiments, the first limiting member comprises a first guide surface and a first blocking block; the first guide surface is integrally formed with the inner wall of the engagement sleeve; the first blocking block is located at one end of the first guide surface close to the second conical tooth, and is flush with one end of the first conical tooth.

[0012] In some embodiments, the second limiting member comprises a second guide surface and a second blocking block; the second guide surface is integrally formed with the inner wall of the engagement sleeve; the second blocking block is located at one end of the second guide surface close to the first conical tooth, and is flush with one end of the second conical tooth.

[0013] In some embodiments, the first blocking block and the second blocking block are parallel, and there is a gap between the first blocking block and the second blocking block.

[0014] In some embodiments, a plurality of first limiting members are arranged at intervals along the axial direction of the engagement sleeve; and / or, a plurality of second limiting members are arranged at intervals along the axial direction of the engagement sleeve.

[0015] In some embodiments, the gear shifting system further comprises: the rack portion and the fork shaft are detachably connected through a first pin shaft assembly; and / or, the fork shaft and the fork are detachably connected through a second pin shaft assembly.

[0016] In some embodiments, the fork shaft is provided with a first counterbore, the bottom of the first counterbore is provided with a conical surface; the fork shaft and the rack are detachably connected through a first locking screw, wherein the top of the first locking screw is also provided with a conical surface; and / or, the fork shaft is provided with a second counterbore, the bottom of the second counterbore is provided with a conical surface; the fork shaft and the fork are detachably connected through a second locking screw, wherein the top of the second locking screw is also provided with a conical surface.

[0017] In some embodiments, the gear shifting system further comprises:

[0018] a housing comprising a mounting cavity; the driving assembly, the rack portion and the fork assembly are located in the mounting cavity;

[0019] a limiting mechanism comprising a screw plug, an elastic member and a ball; the screw plug and the elastic member are located inside the mounting cavity, the screw plug abuts against the elastic member, so that the ball is located between the elastic member and the fork shaft;

[0020] The shift fork shaft is provided with a first limiting groove, a second limiting groove and a third limiting groove; a bottom of at least one of the first limiting groove, the second limiting groove and the third limiting groove is provided with a plane; and the ball is selectively located in the first limiting groove, the second limiting groove and the third limiting groove.

[0021] In some embodiments, the first limiting groove, the second limiting groove and the third limiting groove are all arc-shaped grooves, and a bottom of each of the arc-shaped grooves is provided with a plane, so that the ball is in abutment with the plane.

[0022] In some embodiments, the shift fork assembly further comprises:

[0023] A shaft sleeve is fixedly connected with the housing, the shift fork shaft passes through the shaft sleeve, and a gap exists between the shift fork shaft and the shaft sleeve; and the material of the shaft sleeve is softer than the material of the shift fork shaft.

[0024] In some embodiments, the gear mechanism further comprises a gear shaft and a gear seat, the first gear and the second gear are both mounted on the gear shaft, and the first gear and the second gear are located on two sides of the gear seat; and the meshing sleeve is sleeved on the outer wall of the gear seat.

[0025] The gear seat is provided with an oil channel penetrating through the radial direction of the gear seat, so as to lubricate the meshing sleeve and the gear seat.

[0026] In some embodiments, the gear shifting system further comprises:

[0027] An angle sensor is mounted on the gear output shaft of the driving assembly, so as to output a corresponding voltage signal according to the rotation angle and rotation direction of the gear output shaft.

[0028] The embodiment of the present application further provides an electric drive axle comprising the gear shifting system provided by any of the technical solutions of the present application.

[0029] The embodiment of the present application further provides an engineering vehicle comprising the gear shifting system provided by any of the technical solutions of the present application, or comprising the electric drive axle provided by any of the technical solutions of the present application.

[0030] The embodiment of the present application further provides a gear shifting method, which is implemented by using the gear shifting system provided by any of the technical solutions of the present application, and comprises the following steps:

[0031] According to the gear shifting signal, the meshing sleeve is moved along the axial direction thereof to a position in pre-contact with a target gear; wherein the target gear is one of the first gear and the second gear.

[0032] controlling the rotating speed of the engagement sleeve so that the rotating speed difference between the engagement sleeve and the target gear is a set value;

[0033] continuing to move the engagement sleeve along the axial direction so that the engagement sleeve is engaged with the target gear.

[0034] In some embodiments, a duty cycle of 20% to 30% is applied to the driving assembly so that the engagement sleeve is moved along the axial direction of itself to a position pre-contacting with the target gear.

[0035] In some embodiments, the set value is 10 r / min to 20 r / min.

[0036] In some embodiments, the engagement sleeve is moved according to the following steps:

[0037] When the gear shifting signal is to shift to the first gear, the power output shaft is rotated in the first direction, and the power output shaft drives the engagement sleeve to move towards the first gear via the rack, the fork shaft and the fork, so that the engagement sleeve is engaged with the first gear.

[0038] In some embodiments, the engagement sleeve is moved according to the following steps:

[0039] When the gear shifting signal is to shift to the second gear, the power output shaft is rotated in the second direction, and the power output shaft drives the engagement sleeve to move towards the second gear via the rack, the fork shaft and the fork, so that the engagement sleeve is engaged with the second gear.

[0040] The embodiments of the present application also provide a gear shifting device, comprising:

[0041] a memory; and

[0042] a processor coupled to the memory, the processor being configured to execute the gear shifting method according to any of the embodiments of the present application based on the instructions stored in the memory.

[0043] The embodiments of the present application further provide a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the gear shifting method according to any of the embodiments of the present application.

[0044] The shift system provided by the technical scheme has the first limiting piece and / or the second limiting piece arranged on the inner wall of the engaging sleeve, so that the movement limit position of the engaging sleeve is limited. During the shift, the engaging sleeve cannot move unlimitedly towards the target gear to be engaged, but is limited in a specific limit position. After the engaging sleeve moves to the limit position, the engaging sleeve will not continue to move even if it is subjected to the thrust of the tapered teeth of the target gear, but is stably limited in the limit position. The structure makes the engaging sleeve stably keep in the limit position, reduces or even avoids the mutual abrasion between the engaging sleeve and the shift fork due to the excessive displacement of the engaging sleeve, and improves the reliability of the shift system. BRIEF DESCRIPTION OF DRAWINGS

[0045] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and serve to explain the principles of the application. In the drawings:

[0046] Figure 1 Part of the shift system provided by the embodiments of the application is shown in the partial structure schematic view.

[0047] Figure 2 Another part of the shift system provided by the embodiments of the application is shown in the partial structure schematic view.

[0048] Figure 3 The engaging sleeve of the shift system provided by the embodiments of the application is shown in the partial structure schematic view.

[0049] Figure 4 The shift fork shaft of the shift system provided by the embodiments of the application is shown in the partial structure schematic view.

[0050] Figure 5 The shift system provided by some other embodiments of the application is shown in the partial structure schematic view.

[0051] Figure 6 The shift system provided by some other embodiments of the application is shown in the partial structure schematic view.

[0052] Figure 7 The shift method provided by some embodiments of the application is shown in the schematic view.

[0053] Figure 8 The shift method provided by some embodiments of the application is shown in the logic schematic view.

[0054] Reference signs:

[0055] 1, drive assembly; 11, power source; 12, power output shaft; 13, gear output shaft;

[0056] 2, rack part; 21, body; 22, rack; 210, mounting through hole;

[0057] 3. Shift fork assembly; 31. Shift fork shaft; 32. Shift fork; 311. First countersunk hole; 312. Second countersunk hole; 313. First limiting groove; 314. Second limiting groove; 315. Third limiting groove; 33. Bushing; 34. First pin assembly; 341. First pin; 342. Second pin; 35. Second pin assembly; 351. Third pin; 352. Fourth pin; m. First pin hole; n. Second pin hole;

[0058] 4. Gear mechanism; 41. First gear; 411. Engaging gear teeth of the first gear; 412. Third bevel tooth; 42. Second gear; 421. Engaging gear teeth of the second gear; 422. Fourth bevel tooth; 43. Engaging sleeve; 431. First limiting member; 432. Second limiting member; 433. First bevel tooth; 434. Second bevel tooth; 431a. First guide surface; 431b. First blocking block; 432a. Second guide surface; 432b. Second blocking block; 44. Gear seat; 440. Oil passage;

[0059] 5. First locking screw;

[0060] 6. Second locking screw;

[0061] 7. Limiting mechanism; 71. Plug; 72. Elastic element; 73. Ball;

[0062] 8. First iron wire;

[0063] 9. The second wire;

[0064] 10. Angle sensor. Detailed Implementation

[0065] The following is combined Figures 1-8 The technical solutions provided by this invention will be described in more detail below. The descriptions of exemplary embodiments are merely illustrative and are in no way intended to limit this disclosure or its application or use. This disclosure can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to make this disclosure thorough and complete, and to fully express the scope of this disclosure to those skilled in the art. It should be noted that, unless otherwise specifically stated, the relative arrangement of components and steps, the composition of materials, numerical expressions, and values ​​set forth in these embodiments should be interpreted as merely exemplary and not as limiting.

[0066] The terms “first,” “second,” and similar words used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different parts. Words such as “including” or “contains” mean that the element preceding the word covers the element listed after the word, and do not exclude the possibility of covering other elements as well.

[0067] In this disclosure, when a specific device is described as being located between a first device and a second device, an intermediary device may or may not be present between the specific device and the first or second device. When a specific device is described as being connected to other devices, the specific device may be directly connected to the other devices without an intermediary device, or it may be not directly connected to the other devices but have an intermediary device.

[0068] All terms used in this disclosure, including technical or scientific terms, have the same meaning as understood by one of ordinary skill in the art to which this disclosure pertains, unless otherwise specifically defined. It should also be understood that terms defined in a general dictionary, such as a dictionary, should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and not as having an idealized or highly formalized meaning, unless expressly defined herein.

[0069] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment shall be considered part of the specification.

[0070] The dimensions of the various parts shown in the accompanying drawings are not drawn to actual scale. Common structural elements or elements of the same kind are given the same reference numerals in the various drawings, and repeated descriptions of them are omitted where appropriate.

[0071] The inventors discovered that in related technologies, to improve the success rate of gear shifting, beveled teeth are designed to mesh with the engagement sleeve and the shift gear. The interaction between these beveled teeth provides axial force for the axial movement of the engagement sleeve, making it easier for the engagement sleeve and the shift gear to mesh. However, these beveled teeth cause the engagement sleeve to continue moving in the gear-shifting direction under axial force even after the shift fork is in position, resulting in continuous wear between the shift fork and the engagement sleeve. The technical solution provided by the embodiments of the present invention can effectively limit the engagement sleeve, reducing or even preventing continuous wear between the shift fork and the engagement sleeve.

[0072] See Figures 1 to 3This invention provides a gear shifting system, including a drive assembly 1, a rack section 2, a shift fork assembly 3, and a gear mechanism 4. The drive assembly 1 includes a power source 11, a power output shaft 12, and a gear output shaft 13, which are driven together. The power output shaft 12 is configured to drive the gear output shaft 13 to rotate. The rack section 2 includes a body 21 and a rack 22 fixedly connected to or integrally formed with the body 21; the rack 22 meshes with the gear output shaft 13. The body 21 has a mounting through hole 210. The shift fork assembly 3 includes a shift fork shaft 31 and a shift fork 32; the middle part of the shift fork shaft 31 is mounted in and fixedly connected to the mounting through hole 210; the shift fork 32 is fixedly connected to the portion of the shift fork shaft 31 located outside the mounting through hole 210. The gear mechanism 4 includes a first gear 41, a second gear 42, and a meshing sleeve 43. The engagement sleeve 43 is connected to the shift fork 32 for transmission. Under the drive of the shift fork 32, it can selectively engage with the first gear 41 and the second gear 42 to achieve gear shifting. The inner wall of the engagement sleeve 43 is provided with a first limiting member 431 and / or a second limiting member 432 to limit the movement limit position of the engagement sleeve 43.

[0073] Referring to Figure 1, the power source of the drive assembly 1 can be any one of mechanical power, hydraulic power, pneumatic power, or electric power; in some embodiments, when the engineering vehicle is a new energy vehicle, the drive assembly 1 uses an electric motor as the power source 11. The power output of the motor is transmitted to the power output shaft 12, and the power output shaft 12 and the gear output shaft 13 are driven by transmission components such as keys. When the motor rotates in the first direction, it drives the power output shaft 12 and the gear output shaft 13 to rotate in the first direction; when the motor rotates in the second direction, it drives the power output shaft 12 and the gear output shaft 13 to rotate in the second direction. The first direction is, for example, one of clockwise and counterclockwise directions, and the second direction is the other of clockwise and counterclockwise directions.

[0074] by Figure 1 Taking the direction shown as an example, the first direction is counterclockwise. After the motor rotates, the power output shaft 12 and the gear output shaft 13 both rotate counterclockwise. The rack 22, the shift fork shaft 31 and the shift fork 32 all move to the right, driving the meshing sleeve 43 to move to the right. The meshing sleeve 43 finally meshes with the first gear 41, realizing the engagement of the first gear.

[0075] by Figure 1 Taking the direction shown as an example, the second direction is clockwise. After the motor rotates, the power output shaft 12 and the gear output shaft 13 both rotate clockwise. The rack 22, the shift fork shaft 31 and the shift fork 32 all move to the left, driving the meshing sleeve 43 to move to the left. The meshing sleeve 43 finally meshes with the second gear 42, realizing the second gear.

[0076] This direction will be used as a reference throughout the following text. It should be noted that when the placement of the components changes, the first and second directions will also be adjusted accordingly. All embodiments of this technical solution are based on this direction. Figure 1 The directions shown describe the first and second directions.

[0077] See also Figure 1 The gear output shaft 13 is a gear shaft, and its outer wall is provided with a ring of teeth for meshing. These teeth enable the gear output shaft 13 to mesh with the rack 22.

[0078] by Figure 1 Taking the direction shown as an example, a row of racks 22 is provided on the top of the body 21 of the rack section 2, and the body 21 and the racks 22 are integrally formed. The length of the racks 22 meets the shift stroke requirements. In the initial state, the gear output shaft 13 is approximately located at the middle position along the length direction of the racks 22. When shifting to the first gear, the gear output shaft 13 rotates along the first direction, driving the racks 22 to move to the right, so that the gear output shaft 13 meshes with the teeth on the left edge of the racks 22. When shifting to the second gear, the gear output shaft 13 rotates along the second direction, driving the racks 22 to move to the left, so that the gear output shaft 13 meshes with the teeth on the right edge of the racks 22.

[0079] The rack part 2 has a through mounting hole 210 on its body 21. The shift fork shaft 31 of the shift fork assembly 3 is fixedly connected to the mounting hole 210. The two are fixedly connected by components such as pins and connecting screws, which will be described later. Then, the linear motion of the rack part 2 drives the shift fork shaft 31 to move linearly in sync.

[0080] See also Figure 1 In some embodiments, the rack portion 2 and the shift fork shaft 31 are detachably connected via a first pin assembly 34. The first pin assembly 34 includes a first pin 341 and a second pin 342. The first pin 341 is a hollow pin, and its sidewall has an opening along its axial direction. The body 21 of the rack portion 2 and the shift fork shaft 31 each have a first pin hole m; the first pin 341 is inserted into the first pin hole m. The second pin 342 is inserted into the first pin 341 with an interference fit to achieve double fastening, making the connection between the rack portion 2 and the shift fork shaft 31 more reliable.

[0081] In some embodiments, the shift fork assembly 3 further includes a bushing 33, which is fixedly connected to the housing of the shift system. The shift fork shaft 31 passes through the bushing 33, and there is a gap between them. The material of the bushing 33 is softer than that of the shift fork shaft 31. The shift fork shaft 31 moves linearly relative to the bushing 33, and the bushing 33 provides support for the shift fork shaft 31. The overall material or inner wall material of the bushing 33 is softer than that of the shift fork shaft 31 to prevent wear on the shift fork shaft 31.

[0082] See also Figure 1 andFigure 2 The shift fork shaft 31 does not contact the first gear 41 or the second gear 42. Figure 2 It can be clearly seen that there is a gap between the shift fork shaft 31 and the first gear 41, a gap between the shift fork shaft 31 and the second gear 42, and a gap between the first gear 41 and the second gear 42.

[0083] In some embodiments, the shift fork shaft 31 and the shift fork 32 are detachably connected via a second pin assembly 35. The second pin assembly 35 includes a third pin 351 and a fourth pin 352. The third pin 351 is a hollow pin, and its sidewall has an opening along its axial direction. Both the shift fork shaft 31 and the shift fork 32 have a second pin hole n; the third pin 351 is inserted into the second pin hole n. The fourth pin 352 is inserted into the third pin 351 with an interference fit to achieve double fastening, making the connection between the shift fork shaft 31 and the shift fork 32 more reliable.

[0084] See Figure 1 and Figure 2 In some embodiments, the shifting system further includes an angle sensor 10, which is mounted on the gear output shaft 13 of the shifting mechanism. The angle sensor 10 is used to output a corresponding voltage signal based on the rotation angle and direction of the gear output shaft 13. Specifically, the angle sensor 10 is a magnetic angle sensor. The magnetic angle sensor can sense changes in magnetic field strength, and these changes are processed by a built-in calculation unit to output a voltage value. Based on the rotation angle, the displacement of the rack 22 can be calculated, thereby achieving precise control of the displacement of the shift fork 32 for accurate gear shifting.

[0085] After the shift fork shaft 31 moves into position, the shift fork 32, which is fixedly connected to the shift fork shaft 31, also moves into position. The shift fork 32 is roughly fork-shaped, including a root and two fork sections; the two fork sections surround the outer side of the engagement sleeve 43. The outer wall of the engagement sleeve 43 is provided with a groove, and the two fork sections are respectively provided with protrusions. The protrusions of the two fork sections are engaged in different positions within the same groove, see [reference needed]. Figure 2 .

[0086] See Figure 2 and Figure 3In some embodiments, the inner wall of the engagement sleeve 43 is provided with a ring of first conical teeth 433 and a ring of second conical teeth 434, which are arranged side by side along the axial direction of the engagement sleeve 43. The first gear 41 is correspondingly provided with a third conical tooth 412, and the second gear 42 is correspondingly provided with a fourth conical tooth 422. The first conical tooth 433 and the third conical tooth 412 engage, and the second conical tooth 434 and the fourth conical tooth 422 engage. When first gear is engaged, the first conical tooth 433 and the third conical tooth 412 engage. At this time, the second conical tooth 434 and the fourth conical tooth 422 disengage. When second gear is engaged, the second conical tooth 434 and the fourth conical tooth 422 engage. At this time, the first conical tooth 433 and the third conical tooth 412 disengage.

[0087] At least two adjacent first conical teeth 433 are provided with a first limiting member 431, and at least two adjacent second conical teeth 434 are provided with a second limiting member 432. Multiple first limiting members 431 and multiple second limiting members 432 can be provided along the inner wall of the meshing sleeve 43. Figure 3 The schematic diagram shows that the first limiting member 431 and the second limiting member 432 are located at corresponding positions on the inner wall of the engagement sleeve 43, for example, both at a certain position or several positions in the circumferential direction. This arrangement makes the manufacturing of the engagement sleeve 43 more convenient. Optionally, the first limiting member 431 and the second limiting member 432 can also be located at different positions in the circumferential direction of the engagement sleeve 43.

[0088] like Figure 1 and Figure 3 As shown, the engagement sleeve 43 is internally provided with several evenly distributed first limiting members 431 and second limiting members 432 to solve the problem of mutual wear between the engagement sleeve 43 and the shift fork 32 when the engagement sleeve 43 moves towards the gear due to the axial force of the inverted bevel teeth. If the first limiting members 431 and second limiting members 432 for the engagement sleeve 43 are not provided, or if the limiting members are provided on the shift fork 32, the engagement sleeve 43 will be subjected to a continuous axial force, which will exert lateral pressure on the fork feet of the shift fork 32 and cause continuous wear. The technical solution of this embodiment of the invention adds the first limiting members 431 and second limiting members 432 to limit the engagement sleeve 43, so that the engagement sleeve 43 stops moving when it moves to the end face of the gear engagement teeth, and no longer wears the end face of the fork feet of the shift fork 32. The first limiting members 431 and second limiting members 432 are also used for gear position limiting and calibration during shift self-learning, so that the TCU controls the shift mechanism to find the initial neutral position.

[0089] See Figure 3In some embodiments, the first limiting member 431 includes a first guide surface 431a and a first blocking block 431b; the first guide surface 431a is integrally formed with the inner wall of the engagement sleeve 43; the first blocking block 431b is located at one end of the first guide surface 431a near the second conical tooth 434 and is flush with one end of the first conical tooth 433. The first guide surface 431a is an arc-shaped surface, which makes it easier for the engagement sleeve 43 to slide to the position of engaging with the first gear 41. The first blocking block 431b is a vertical plate, which is disposed on the edge of the first guide surface 431a near the second gear 42. When the engagement sleeve 43 moves to the point where the first gear 41 abuts against the first blocking block 431b of the engagement sleeve 43, the engagement sleeve 43 cannot continue to move in the original direction of movement relative to the first gear 41.

[0090] In the above technical solution, since both the first conical tooth 433 and the third conical tooth 412 are conical, they form an inclined surface fit. When shifting gears, under the axial force of the engagement sleeve 43, the first conical tooth 433 will continuously slide towards the third conical tooth 412. If the first limiting member 431 is not provided, after the gear shifting operation is completed, the first conical tooth 433 of the engagement sleeve 43 may continue to move relative to the third conical tooth 412. In the above technical solution of the present invention, because the first limiting member 431 is provided, when the engagement sleeve 43 moves to the target position during the gear shifting operation, the first limiting member 431 will abut against the end face of the third conical tooth 412 along the axial direction of the first gear 41, so that the engagement sleeve 43 can no longer continue to move relative to the first gear 41.

[0091] See also Figure 3 In some embodiments, the second limiting member 432 includes a second guide surface 432a and a second blocking block 432b; the second guide surface 432a is integrally formed with the inner wall of the engagement sleeve 43; the second blocking block 432b is located at one end of the second guide surface 432a near the first conical tooth 433 and is flush with one end of the second conical tooth 434. The second guide surface 432a is an arc-shaped surface, which makes it easier for the engagement sleeve 43 to slide to the position of engaging with the second gear 42. The second blocking block 432b is a vertical plate, which is disposed on the edge of the second guide surface 432a near the first gear 41. When the engagement sleeve 43 moves to the point where the second gear 42 abuts against the second blocking block 432b of the engagement sleeve 43, the engagement sleeve 43 cannot continue to move in the original direction of movement relative to the second gear 42.

[0092] In the above technical solution, since both the second conical tooth 434 and the fourth conical tooth 422 are conical, they form an inclined surface fit. When shifting to second gear, under the axial force of the engagement sleeve 43, the second conical tooth 434 will continuously slide towards the fourth conical tooth 422. If the second limiting member 432 is not provided, after the second gear shifting operation is completed, the second conical tooth 434 of the engagement sleeve 43 may continue to move relative to the fourth conical tooth 422. In the above technical solution of the present invention, because the second limiting member 432 is provided, when the engagement sleeve 43 moves to the target position during the second gear shifting operation, the second limiting member 432 will abut against the end face of the fourth conical tooth 422 along the axial direction of the second gear 42, so that the engagement sleeve 43 can no longer continue to move relative to the second gear 42.

[0093] See also Figure 3 In some embodiments, the first blocking block 431b and the second blocking block 432b are parallel, and there is a gap between the first blocking block 431b and the second blocking block 432b. This arrangement ensures that the first blocking block 431b and the second blocking block 432b are positioned at the same circumferential position on the engagement sleeve 43 without interfering with each other, making the gear shifting operation more reliable.

[0094] In some embodiments, a plurality of first limiting members 431 are arranged at intervals along the axial direction of the engagement sleeve 43; and / or, a plurality of second limiting members 432 are arranged at intervals along the axial direction of the engagement sleeve 43.

[0095] Multiple first limiting elements 431 are provided to ensure more uniform and reliable circumferential limiting of the engagement sleeve 43 during gear shifting. Multiple second limiting elements 432 are provided to ensure more uniform and reliable circumferential limiting of the engagement sleeve 43 during gear shifting.

[0096] See Figure 1 , Figure 2 and Figure 4 In some embodiments, the shifting system further includes a housing (not shown) and a limiting mechanism 7. The housing includes a mounting cavity; the drive assembly 1, the rack portion 2, and the shift fork assembly 3 are all located within the mounting cavity. The limiting mechanism 7 includes a screw plug 71, an elastic element 72, and a ball 73. The screw plug 71 and the elastic element 72 are both located inside the mounting cavity, with the screw plug 71 abutting against the elastic element 72 so that the ball 73 is positioned between the elastic element 72 and the shift fork shaft 31. The shift fork shaft 31 is provided with a first limiting groove 313, a second limiting groove 314, and a third limiting groove 315; at least one of the first limiting groove 313, the second limiting groove 314, and the third limiting groove 315 has a flat surface at its bottom; the ball 73 is selectively located in one of the first limiting groove 313, the second limiting groove 314, or the third limiting groove 315. The ball 73 can make stable contact with any position on the flat surface.

[0097] The elastic element 72 is specifically, for example, a spring. Under the action of the elastic element 72, the ball 73 is pressed against between the elastic element 72 and the shift fork shaft 31. The ball 73 can be located in any of the first limiting groove 313, the second limiting groove 314, and the third limiting groove 315. Figure 4 As shown, from right to left, the grooves are: first limiting groove 313, second limiting groove 314, and third limiting groove 315. When the engagement sleeve 43 engages with the first gear 41, the ball 73 is pressed into the first limiting groove 313. When the engagement sleeve 43 engages with the second gear 42, the ball 73 is pressed into the third limiting groove 315. When not shifting gears, the engagement sleeve 43 does not engage with either the first gear 41 or the second gear 42, but is positioned between the two gears. In this case, the ball 73 falls into the second limiting groove 314.

[0098] When shifting gears, if the theoretical shifting stroke of the engagement sleeve 43 is L1, the actual shifting stroke is L1±ΔL / 2. If the first limiting groove 313 and the third limiting groove 315 are not provided with a plane, then after shifting, the ball 73 may come into contact with the arc surface of the first limiting groove 313 and the third limiting groove 315. This contact will apply a certain axial force to the shift fork shaft 31, so that the shift fork shaft 31 is still pushed to move after shifting. If the first limiting groove 313 and the third limiting groove 315 are set as planes, then even if the actual shift stroke is L1±ΔL / 2, after the shift is completed, the ball 73 will also contact the plane of the first limiting groove 313 and the third limiting groove 315. This contact method will not apply axial force to the shift fork shaft 31 and will not cause the shift fork shaft 31 to move unexpectedly. This can compensate for the deviation of the shift accuracy controlled by the TCU (Transmission Control Unit), so that the shift stroke is based on the TCU control, avoiding the shift position conflict caused by the inconsistency between the machining or assembly error and the TCU control accuracy deviation, and at the same time avoiding self-locking failure.

[0099] The second limiting groove 314 corresponds to the neutral position. A flat surface is provided at the bottom of the second limiting groove 314 so that the shift fork shaft 31 will not move due to the axial force between the ball 73 and the second limiting groove 314 when in neutral.

[0100] In some embodiments, the width of the planes of the first limiting groove 313, the second limiting groove 314, and the third limiting groove 315, i.e., the dimension of the planes along the axial direction of the shift fork shaft 31, is 1mm ± 0.5mm. Setting these values ​​can effectively compensate for deviations in the shifting accuracy controlled by the TCU, ensuring that the shifting stroke is based on the TCU control.

[0101] In some embodiments, the first limiting groove 313, the second limiting groove 314 and the third limiting groove 315 are all arc-shaped grooves, and the bottom of each arc-shaped groove is provided with a plane so that the ball 73 can optionally abut against the plane, thereby improving the reliability of self-locking, compensating for the deviation of the TCU control shifting accuracy, and making the shifting stroke based on the TCU control.

[0102] Back Figure 1 In some embodiments, the gear mechanism 4 further includes a gear shaft (not shown) and a gear seat 44. The first gear 41, the gear seat 44, and the second gear 42 are all mounted on the gear shaft. The first gear 41 and the second gear 42 are located on both sides of the gear seat 44. The meshing sleeve 43 is sleeved on the outer wall of the gear seat 44. The gear seat 44 is provided with an oil passage 440 that runs through its radial direction to lubricate the meshing sleeve 43 and the gear seat 44.

[0103] During gear shifting, the gear seat 44 remains stationary, while the engagement sleeve 43 moves. Regardless of the position of the engagement sleeve 43, the oil in the oil passage 440 can lubricate the engagement sleeve 43. The splines of both the gear seat 44 and the engagement sleeve 43 are lubricated, which reduces the coefficient of friction of the spline sliding motion from 0.15–0.22 to 0.05–0.1, thus reducing shifting resistance.

[0104] The shifting system provided by the above technical solution can be assembled as a whole in the workshop and then modularly installed on engineering vehicles to improve assembly efficiency.

[0105] See Figure 5 and Figure 6 Other implementation methods will be introduced below.

[0106] In other embodiments, the shift fork shaft 31 is provided with a first countersunk hole 311, the bottom of which is a tapered surface; the shift fork shaft 31 is detachably connected to the rack 22 by a first locking screw 5, wherein the top of the first locking screw 5 is also a tapered surface; and / or, the shift fork shaft 31 is provided with a second countersunk hole 312, the bottom of which is a tapered surface; the shift fork shaft 31 is detachably connected to the shift fork 32 by a second locking screw 6, wherein the top of the second locking screw 6 is also a tapered surface.

[0107] like Figure 5 and Figure 6 As shown, the rack 22 is fitted onto one side of the shift fork shaft 31 and is fixed to the shift fork shaft 31 by the first locking screw 5. The rack 22 has a small hole, and the first locking screw 5 also has a corresponding small hole on its hexagonal surface. The rack 22 and the first locking screw 5 are connected by the first iron wire 8 to prevent loosening.

[0108] The shift fork 32 is fitted onto the other side of the shift fork shaft 31 and is fixed to the shift fork shaft 31 by the second locking screw 6. The shift fork 32 has a small hole and the shift fork 32 and the second locking screw 6 are connected by the second iron wire 9 to prevent loosening.

[0109] The shift fork shaft 31 is provided with a tapered surface that mates with the first locking screw 5 and the second locking screw 6 at the assembly points of the first locking screw 5 and the second locking screw 6, so that the force transmission between the rack 2, the shift fork shaft 31, and the shift fork 32 is more efficient.

[0110] In some scenarios, when there is no assembly space inside the gearbox due to design limitations, and the rack 22, shift fork 32 and shift fork shaft 31 cannot be pre-assembled into components before being assembled with the gearbox housing and gear set, the parts can be disassembled inside the gearbox using the first locking screw 5, the second locking screw 6, the first wire 8 and the second wire 9 to improve the flexibility of the shift system installation.

[0111] This invention also provides an electric drive axle, including the shifting system provided by any of the technical solutions of this invention.

[0112] This invention also provides an engineering vehicle, including a gear shifting system provided by any of the technical solutions of this invention; or, including an electric drive axle provided by any of the technical solutions of this invention.

[0113] See Figure 7 and Figure 8 This invention also provides a gear shifting method, implemented using the gear shifting system provided by any of the technical solutions of this invention. The gear shifting method includes the following steps:

[0114] In step S100, according to the shift signal, the engagement sleeve 43 is moved along its own axial direction to a position where it is about to contact the target gear; wherein the target gear is one of the first gear 41 and the second gear 42. When shifting to first gear, the target gear is the first gear 41. When shifting to second gear, the target gear is the second gear 42.

[0115] In step S100 above, whether shifting into first gear or second gear, a duty cycle of 20% to 30% is applied to the drive assembly 1 so that the engagement sleeve 43 moves along its axial direction to a position where it is about to make contact with the target gear. Taking first gear as an example, the engagement sleeve 43 is engaged until it just makes contact with the gear teeth, which is the pre-contact position. This position can be preset in the program. Figure 1The first gear engagement tooth 411 is the first part of the first gear 41 to contact the engagement sleeve 43. When the engagement sleeve 43 and the first gear engagement tooth 411 are misaligned, causing an angular change in the angle sensor 10, the angle sensor will output a corresponding voltage signal. Furthermore, the voltage signal output by the angle sensor differs depending on whether the power source 11 rotates in the first or second direction. Based on the output voltage signal, the shifting progress can be determined. The TCU then controls the PID to quickly shift to the gear travel position, preventing the shifting motor from stalling and burning out, and avoiding shifting impacts or tooth knocking that could cause wear on the gear engagement teeth, generate metal filings, and affect the cleanliness of the electric drive axle. In the initial state, the engagement sleeve 43 does not contact the first gear engagement tooth 411; otherwise, in neutral, the engagement sleeve 43 and the first gear 41 will engage, which would be dangerous. The first gear engagement tooth 411 has a tapered surface on the side facing the engagement sleeve 43. The tapered surface ensures that the engagement sleeve 43 and the first gear 41 do not mesh and do not contact each other when in neutral; otherwise, when not in gear, the engagement sleeve 43 and the first gear 41 will continuously grind against each other. When first gear is engaged, the TCU controls the shifting mechanism to drive the output gear shaft to rotate counterclockwise to shift to the correct gear. The angle sensor 10 feeds back a voltage signal value of 1.3V, and then feeds back the engaged gear to the VCU. The instrument panel in the cab displays "1st gear".

[0116] When shifting to second gear, the engagement process between the meshing sleeve 43 and the second gear 42 is similar to that of first gear. A duty cycle of 20%–30% is applied to the drive assembly 1, causing the meshing sleeve 43 to move axially to a position where it is about to contact the target gear. The gear is shifted until the meshing sleeve 43 just contacts the engagement teeth 421 of the second gear, reaching the pre-contact position. When the meshing sleeve 43 and the engagement teeth 421 of the second gear misalign, causing an angle change in the angle sensor 10, the TCU controls the PID to quickly shift to the gear travel position, preventing the shifting motor from stalling and burning out, and preventing shifting impacts or tooth breakage that could cause wear on the gear engagement teeth, generate metal filings, and affect the cleanliness of the electric drive bridge. In its original state, the meshing sleeve 43 does not contact the engagement teeth 421 of the second gear; otherwise, in neutral, the meshing sleeve 43 and the second gear 42 would engage, which would be dangerous. The second gear engagement tooth 421 has a tapered surface on the side facing the engagement sleeve 43. The tapered surface ensures that the engagement sleeve 43 and the first gear 41 do not mesh or contact when in neutral; otherwise, when no gear is engaged, the engagement sleeve 43 and the second gear 42 will continuously grind. When shifting to second gear, the TCU controls the shifting mechanism to drive the output gear shaft to rotate clockwise to the position. The angle sensor 10 feeds back a 1.3V voltage signal value to the TCU, and then feeds back the engaged gear to the VCU. The instrument panel in the cab displays "2nd gear".

[0117] Step S200: Control the rotational speed of the meshing sleeve 43 so that the speed difference between the meshing sleeve 43 and the target gear is a set value. In some embodiments, the set value is 10 r / min to 20 r / min.

[0118] The rotational speed of the meshing sleeve 43 is greater than that of the target gear, and the difference between the two is 10 r / min to 20 r / min. This can achieve co-gear meshing, reduce the wear of the meshing sleeve 43 and the target gear, and shorten the shifting time.

[0119] The aforementioned gear-shifting process does not directly engage the meshing sleeve 43 with the target gear. Direct engagement would cause the meshing sleeve 43 to impact the target gear, resulting in significant impact and potentially causing shifting failure due to misalignment of the teeth between the meshing sleeve 43 and the target gear. This technical solution first brings the meshing sleeve 43 close to the target gear, achieving a pre-contact state. At this point, the friction between the two limits the misalignment to within one tooth. Under these conditions, because the relative rotational speed between the meshing sleeve 43 and the target gear is relatively low, smooth engagement can be achieved solely through friction. Specifically, the meshing teeth of the meshing sleeve 43 slide smoothly along the impact tooth surface into the tooth groove of the target gear's engagement teeth, avoiding retraction along the tooth surface, thereby reducing wear and shortening shifting time. This smooth tooth engagement method is more efficient and does not damage the splines of the meshing sleeve 43 and the target gear.

[0120] In step S300, the engagement sleeve 43 continues to move along the axial direction of the shift fork, so that the engagement sleeve 43 engages with the target gear.

[0121] The power of the engagement sleeve 43 comes from the drive assembly 1. When the first gear is engaged, the power transmission path is as follows: the power output shaft 12 rotates in the first direction, and drives the engagement sleeve 43 to move toward the first gear 41 in sequence via the rack 22, the shift fork shaft 31, and the shift fork 32, so as to realize the engagement of the engagement sleeve 43 with the first gear 41.

[0122] When in second gear, the power transmission path is as follows: the power output shaft 12 rotates in the second direction, and drives the meshing sleeve 43 to move toward the second gear 42 in sequence via the rack 22, shift fork shaft 31, and shift fork 32, thereby realizing the meshing of the meshing sleeve 43 and the second gear 42.

[0123] Figure 8 The diagram illustrates the entire shifting logic. Upon receiving the shift start signal, the MCU (Microcontroller Unit) performs a torque clearing operation, resetting the torque to zero. After torque clearing, the TCU (Transmission Control Unit) disengages the gear, i.e., engages neutral. The neutral voltage value fed back by angle sensor 10 indicates successful disengagement. After disengagement, the MCU adjusts the speed until the engagement sleeve's rotational speed is 10-20 r / min higher than the target gear's speed. Then, the TCU controls the PID controller for two-stage gear engagement. The target gear voltage value fed back by angle sensor 10 indicates successful shifting. After shifting, the VCU (Vehicle Control Unit) updates the gear position; the MCU increases torque.

[0124] The above technical solution offers high reliability and high efficiency in gear shifting.

[0125] This invention provides a gear shifting device, including a memory and a processor coupled to the memory. The processor is configured to execute the gear shifting method in any of the foregoing embodiments based on instructions stored in the memory.

[0126] Memory may include, for example, system memory, fixed non-volatile storage media, etc. System memory may store, for example, the operating system, application programs, boot loader, and other programs.

[0127] Some embodiments of this disclosure also provide a computer-readable storage medium having a computer program stored thereon. When executed by a processor, the program implements the gear-shifting method of any of the above embodiments.

[0128] The processors described herein may include general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in alternatives, it may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors cooperating with a DSP core, or any other such configuration.

[0129] Storage media can be any available medium that can be accessed by a computer. By way of example and not limitation, such computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disc storage, disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Any connection is also properly referred to as computer-readable media. For example, if software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then such coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of media. As used herein, disk and disc include compact discs (CDs), laser discs, optical discs, digital multi-purpose discs (DVDs), floppy disks, and Blu-ray discs, where disks typically reproduce data magnetically, and discs reproduce data optically using lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0130] Those skilled in the art will understand that the method embodiments of this disclosure can be provided as a method, system, or computer program product. Therefore, this disclosure can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this disclosure can take the form of a computer program product embodied on one or more computer-usable non-transitory storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0131] This disclosure is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0132] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a processFigure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0133] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0134] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0135] In the description of this invention, each technical feature may be combined with other technical features where feasible.

[0136] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A gear shifting system, characterized in that, include: The drive assembly (1) includes a power source (11), a power output shaft (12), and a gear output shaft (13). The power source (11) is driven to the power output shaft (12), and the power output shaft (12) is driven to the gear output shaft (13). The rack section (2) includes a body (21) and a rack (22) that is fixedly connected to or integrally formed with the body (21); the rack (22) meshes with the gear output shaft (13); the body (21) is provided with a mounting through hole (210). The shift fork assembly (3) includes a shift fork shaft (31) and a shift fork (32); the middle part of the shift fork shaft (31) is installed in the mounting through hole (210) and is fixedly connected to the mounting through hole (210); the shift fork (32) is fixedly connected to the part of the shift fork shaft (31) located outside the mounting through hole (210); The gear mechanism (4) includes a first gear (41), a second gear (42), and a meshing sleeve (43); the meshing sleeve (43) is connected to the shift fork (32) for transmission, so that it can selectively mesh with one of the first gear (41) and the second gear (42) under the drive of the shift fork (32) to realize gear shifting; wherein, the inner wall of the meshing sleeve (43) is provided with a first limiting member (431) and a second limiting member (432) to limit the movement limit position of the meshing sleeve (43); The inner wall of the meshing sleeve (43) is provided with a set of first conical teeth (433) and a set of second conical teeth (434); the first gear (41) is provided with a third conical tooth (412), and the second gear (42) is provided with a fourth conical tooth (422). The first limiting member (431) is configured to prevent the first conical tooth (433) of the engagement sleeve (43) from continuing to move relative to the third conical tooth (412) after the gear shifting operation is completed; when the engagement sleeve (43) moves to the target position after the gear shifting operation, the first limiting member (431) abuts against the end face of the third conical tooth (412) along the axial direction of the first gear (41), so that the engagement sleeve (43) can no longer continue to move relative to the first gear (41); The second limiting member (432) is configured to prevent the second conical tooth (434) of the engagement sleeve (43) from continuing to move relative to the fourth conical tooth (422) after the second gear shifting operation is completed; when the engagement sleeve (43) moves to the target position after the second gear shifting operation, the second limiting member (432) abuts against the end face of the fourth conical tooth (422) along the axial direction of the second gear (42), so that the engagement sleeve (43) cannot continue to move relative to the second gear (42); The shifting system also includes: An angle sensor (10) is installed on the gear output shaft (13) of the drive assembly (1) to output a corresponding voltage signal according to the rotation angle and rotation direction of the gear output shaft (13); The shifting system is configured to execute a shifting method, which includes the following steps: According to the shift signal, the engagement sleeve (43) is moved along its own axial direction to a position where it is in pre-contact with the target gear; wherein, the target gear is one of the first gear (41) and the second gear (42); a duty cycle of 20% to 30% is applied to the drive assembly (1) so that the engagement sleeve (43) moves along its own axial direction to a position where it is in pre-contact with the target gear; The rotational speed of the meshing sleeve (43) is controlled so that the speed difference between the meshing sleeve (43) and the target gear is a set value; the rotational speed of the meshing sleeve (43) is greater than the rotational speed of the target gear, and the set value is 10 r / min to 20 r / min, so as to achieve co-gear meshing; Continue to move the engagement sleeve (43) axially so that the engagement sleeve (43) engages with the target gear.

2. The shifting system according to claim 1, characterized in that, The first conical tooth (433) and the second conical tooth (434) are arranged side by side along the axial direction of the engagement sleeve (43); at least two adjacent first conical teeth (433) are provided with the first limiting member (431), and at least two adjacent second conical teeth (434) are provided with the second limiting member (432).

3. The shifting system according to claim 2, characterized in that, The first limiting member (431) includes a first guide surface (431a) and a first blocking block (431b); the first guide surface (431a) is integrally formed with the inner wall of the engagement sleeve (43); the first blocking block (431b) is located at one end of the first guide surface (431a) near the second conical tooth (434) and is flush with one end of the first conical tooth (433).

4. The shifting system according to claim 3, characterized in that, The second limiting member (432) includes a second guide surface (432a) and a second blocking block (432b); the second guide surface (432a) is integrally formed with the inner wall of the engagement sleeve (43); the second blocking block (432b) is located at one end of the second guide surface (432a) near the first conical tooth (433) and is flush with one end of the second conical tooth (434).

5. The shifting system according to claim 4, characterized in that, The first blocking block (431b) and the second blocking block (432b) are parallel, and there is a gap between the first blocking block (431b) and the second blocking block (432b).

6. The shifting system according to claim 1, characterized in that, A plurality of first limiting members (431) are arranged at intervals along the axial direction of the engagement sleeve (43); and / or, a plurality of second limiting members (432) are arranged at intervals along the axial direction of the engagement sleeve (43).

7. The shifting system according to claim 1, characterized in that, The rack portion (2) is detachably connected to the shift fork shaft (31) via a first pin assembly (34); and / or, the shift fork shaft (31) is detachably connected to the shift fork (32) via a second pin assembly (35).

8. The shifting system according to claim 1, characterized in that, The shift fork shaft (31) is provided with a first countersunk hole (311), the bottom of which is set as a tapered surface; the shift fork shaft (31) is detachably connected to the rack (22) by a first locking screw (5), wherein the top of the first locking screw (5) is also set as a tapered surface; and / or, the shift fork shaft (31) is provided with a second countersunk hole (312), the bottom of which is set as a tapered surface; the shift fork shaft (31) is detachably connected to the shift fork (32) by a second locking screw (6), wherein the top of the second locking screw (6) is also set as a tapered surface.

9. The shifting system according to claim 1, characterized in that, Also includes: The housing includes a mounting cavity; the drive assembly (1), the rack portion (2), and the shift fork assembly (3) are all located in the mounting cavity; The limiting mechanism (7) includes a screw plug (71), an elastic element (72), and a ball (73); the screw plug (71) and the elastic element (72) are both located inside the mounting cavity, and the screw plug (71) abuts against the elastic element (72) so that the ball (73) is located between the elastic element (72) and the shift fork shaft (31); The shift fork shaft (31) is provided with a first limiting groove (313), a second limiting groove (314) and a third limiting groove (315); at least one of the first limiting groove (313), the second limiting groove (314) and the third limiting groove (315) has a flat surface at its bottom; the sphere (73) is located in one of the first limiting groove (313), the second limiting groove (314) and the third limiting groove (315).

10. The shifting system according to claim 9, characterized in that, The first limiting groove (313), the second limiting groove (314) and the third limiting groove (315) are all arc-shaped grooves, and the bottom of each arc-shaped groove is provided with a flat surface so that the sphere (73) can optionally abut against the flat surface.

11. The shifting system according to claim 9, characterized in that, The fork assembly (3) further includes: A bushing (33) is fixedly connected to the housing, and the shift fork shaft (31) passes through the bushing (33) with a gap between them; the material of the bushing (33) is softer than the material of the shift fork shaft (31).

12. The shifting system according to claim 1, characterized in that, The gear mechanism (4) further includes a gear shaft and a gear seat (44). The first gear (41), the gear seat (44) and the second gear (42) are all mounted on the gear shaft, and the first gear (41) and the second gear (42) are located on both sides of the gear seat (44). The meshing sleeve (43) is sleeved on the outer wall of the gear seat (44). The gear seat (44) is provided with an oil passage (440) that runs through its radial direction to lubricate the meshing sleeve (43) and the gear seat (44).

13. An electric drive bridge, characterized in that, Includes the shifting system described in any one of claims 1 to 12.

14. An engineering vehicle, characterized in that, It includes the shifting system according to any one of claims 1 to 12; or, it includes the electric drive axle according to claim 13.

15. A gear-shifting method, characterized in that, This is achieved using a gear shifting system; The shifting system includes: The drive assembly (1) includes a power source (11), a power output shaft (12), and a gear output shaft (13). The power source (11) is driven to the power output shaft (12), and the power output shaft (12) is driven to the gear output shaft (13). The rack section (2) includes a body (21) and a rack (22) that is fixedly connected to or integrally formed with the body (21); the rack (22) meshes with the gear output shaft (13); the body (21) is provided with a mounting through hole (210). The shift fork assembly (3) includes a shift fork shaft (31) and a shift fork (32); the middle part of the shift fork shaft (31) is installed in the mounting through hole (210) and is fixedly connected to the mounting through hole (210); the shift fork (32) is fixedly connected to the part of the shift fork shaft (31) located outside the mounting through hole (210); The gear mechanism (4) includes a first gear (41), a second gear (42), and a meshing sleeve (43); the meshing sleeve (43) is connected to the shift fork (32) for transmission, so that it can selectively mesh with one of the first gear (41) and the second gear (42) under the drive of the shift fork (32) to realize gear shifting; wherein, the inner wall of the meshing sleeve (43) is provided with a first limiting member (431) and a second limiting member (432) to limit the movement limit position of the meshing sleeve (43); The inner wall of the meshing sleeve (43) is provided with a set of first conical teeth (433) and a set of second conical teeth (434); the first gear (41) is provided with a third conical tooth (412), and the second gear (42) is provided with a fourth conical tooth (422). The first limiting member (431) is configured to prevent the first conical tooth (433) of the engagement sleeve (43) from continuing to move relative to the third conical tooth (412) after the gear shifting operation is completed; when the engagement sleeve (43) moves to the target position after the gear shifting operation, the first limiting member (431) abuts against the end face of the third conical tooth (412) along the axial direction of the first gear (41), so that the engagement sleeve (43) can no longer continue to move relative to the first gear (41); The second limiting member (432) is configured to prevent the second conical tooth (434) of the engagement sleeve (43) from continuing to move relative to the fourth conical tooth (422) after the second gear shifting operation is completed; when the engagement sleeve (43) moves to the target position after the second gear shifting operation, the second limiting member (432) abuts against the end face of the fourth conical tooth (422) along the axial direction of the second gear (42), so that the engagement sleeve (43) cannot continue to move relative to the second gear (42); The shifting system also includes: An angle sensor (10) is installed on the gear output shaft (13) of the drive assembly (1) to output a corresponding voltage signal according to the rotation angle and rotation direction of the gear output shaft (13); The gear shifting method includes the following steps: According to the shift signal, the engagement sleeve (43) is moved along its own axial direction to a position where it is in pre-contact with the target gear; wherein, the target gear is one of the first gear (41) and the second gear (42); a duty cycle of 20% to 30% is applied to the drive assembly (1) so that the engagement sleeve (43) moves along its own axial direction to a position where it is in pre-contact with the target gear; The rotational speed of the meshing sleeve (43) is controlled so that the speed difference between the meshing sleeve (43) and the target gear is a set value; the rotational speed of the meshing sleeve (43) is greater than the rotational speed of the target gear, and the set value is 10 r / min to 20 r / min, so as to achieve co-gear meshing; Continue to move the engagement sleeve (43) axially so that the engagement sleeve (43) engages with the target gear.

16. The gear shifting method according to claim 15, characterized in that, Move the engagement sleeve (43) according to the following steps: When the shift signal is to shift to the first gear, the power output shaft (12) is rotated in the first direction. The power output shaft (12) drives the engagement sleeve (43) to move toward the first gear (41) via the rack (22), the shift fork shaft (31), and the shift fork (32) so as to realize the engagement sleeve (43) and the first gear (41).

17. The gear shifting method according to claim 15, characterized in that, Move the engagement sleeve (43) according to the following steps: When the shift signal is to shift to second gear, the power output shaft (12) is rotated in the second direction. The power output shaft (12) drives the meshing sleeve (43) to move toward the second gear (42) via the rack (22), the shift fork shaft (31), and the shift fork (32) so as to achieve meshing between the meshing sleeve (43) and the second gear (42).

18. A gear shifting device, characterized in that, include: Memory; and A processor coupled to the memory, the processor being configured to execute the shifting method as described in any one of claims 15 to 17 based on instructions stored in the memory.

19. A computer-readable storage medium, characterized in that, It stores a computer program that, when executed by a processor, implements the shifting method as described in any one of claims 15 to 17.

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