Shift damper mechanism and method for an electronically controlled transfer

Abstract

The application relates to a shift buffer mechanism and method of an electric control differential, and belongs to the technical field of differentials. The technical scheme is as follows: the shift buffer mechanism comprises a shift camshaft, an H-L shift fork subassembly, a shift guide shaft and a high-low gear sleeve; the buffer spring mounting seat of the H-L shift fork subassembly moves along the axial direction of the shift guide shaft along the spiral track on the shift camshaft; at this time, the H-L shift fork cannot reach the specified position because the high-low gear sleeve cannot complete the shift action; the buffer spring is compressed by the buffer spring mounting seat and stores kinetic energy; after the problem of the top tooth disappears, the compressed buffer spring releases the stored kinetic energy; the H-L shift fork is pushed by the buffer spring and reaches the specified position to complete the shift action. The application has the beneficial effects that when the high-low gear switching cannot complete the shift action temporarily due to the top tooth and other reasons, the kinetic energy is stored and released by the buffer spring, the delayed shift is realized without affecting the motor subassembly, and the performance of the differential box is improved.

Description

Technical Field

[0001] This invention relates to a shift buffer mechanism and method for an electronically controlled transfer case, belonging to the field of transfer case technology. Background Technology

[0002] In vehicle drivetrain systems, a transfer case is typically used to achieve four-wheel drive functionality. Four-wheel drive includes two-wheel drive high speed, four-wheel drive high speed, and four-wheel drive low speed. During the shifting between four-wheel drive high speed and four-wheel drive low speed, the lack of a synchronizer in the mechanical structure can easily lead to problems such as gear misalignment during high-low gear switching, resulting in incomplete shifting and affecting signal feedback between the motor sub-assembly and the vehicle. For example, Chinese patent application CN2025214126973, entitled "An Electronically Controlled Transfer Case Shifting Mechanism with Neutral Gear," discloses a high / low gear fork that slides between the input shaft and planetary carrier via a high / low gear sleeve spline to control the switching between high and low speeds. However, the mechanical structure between the high / low gear fork, the high / low gear sleeve, and the corresponding gears lacks a synchronizer, which can easily lead to problems such as gear misalignment during high / low gear switching.

[0003] To address the aforementioned issues, Chinese patent application CN201410521812, entitled "Electrically Controlled Transfer Case Gear Shifting Device," discloses a mechanism where a screw on a shaft moves within a groove on a shift fork, pushing the shift fork into the target gear. The shifting sequence of each gear is determined by the groove design on the shift fork, preventing motor stalling and damage to the motor and operating mechanism when the shift encounters resistance. However, this design suffers from the following technical problems: 1. High processing difficulty, significant impact on shift fork strength, and cumbersome subsequent assembly. 2. The buffer structure is a buffer assembly, installed externally with the motor and reducer assembly, relatively increasing the external structure and thus requiring more space for the entire housing. 3. The buffer structure is a circumferential design, with three buffer springs placed on a single disc. The disc rotates, compressing the springs to achieve buffering, but this also results in the circumferential angle being evenly divided, leading to a smaller circumferential buffer stroke and less spring compression during buffering, thus limiting the buffering range of the motor rotation angle.

[0004] Therefore, achieving delayed shifting or resolving shifting issues caused by top teeth through a simple shifting buffer mechanism without affecting the motor sub-assembly is a current technical challenge in this field. Summary of the Invention

[0005] Limited by the above problems, the present invention aims to provide a shift buffer mechanism and method for an electronically controlled transfer case. The buffer structure is placed inside the HL shift fork sub-assembly, which has no impact on the external space of the housing. The buffer structure consists only of a buffer spring mounting seat, a buffer spring, and a buffer spring positioning plate. The structure is simple and the overall installation ensures convenient installation. By storing and releasing kinetic energy through the buffer spring, delayed shifting is achieved under normal operation of the motor sub-assembly to solve the problems that occur during shifting, such as the top gear shifting.

[0006] The technical solution of this invention is: A shift buffer mechanism for an electronically controlled transfer case includes an HL shift fork subassembly mounted on a shift guide shaft. The HL shift fork subassembly includes an HL shift fork, a buffer spring mounting seat, a buffer spring, and a buffer spring positioning plate. The top of the buffer spring mounting seat is open, and mounting plates are provided at both ends of the buffer spring mounting seat. A circular hole is provided on the mounting plate. Two buffer spring baffles are provided in the middle of the buffer spring mounting seat. A semi-circular hole is provided on the buffer spring baffle. The HL shift fork includes a shift fork body and a base. The bottom of the base is open, and two mounting plates are provided at both ends of the base. The space between the two mounting plates forms a buffer spring mounting seat moving chamber. The buffer spring mounting seat is set in the buffer spring mounting seat moving chamber and can move left and right. Two round holes are opened on the mounting plates. Two buffer spring baffles are provided in the middle of the base. Two semi-circular holes are opened on the buffer spring baffles. The HL shift fork and buffer spring mounting base are arranged vertically opposite each other, and the semi-circular hole two and the semi-circular hole one correspond to each other to form a complete circular hole three. The shift guide shaft passes through the circular hole one, the circular hole two and the circular hole three and is assembled with the HL shift fork sub-assembly. The two buffer spring baffles are respectively vertically aligned with the two buffer spring baffles, and the space between them forms a buffer spring mounting chamber. Buffer spring positioning plates are installed on both the left and right ends of the buffer spring and mounted on the shift guide shaft inside the buffer spring mounting chamber. The upper parts of the two buffer spring positioning plates are in contact with the two buffer spring baffles, and the lower parts of the two buffer spring positioning plates are in contact with the two buffer spring baffles.

[0007] Furthermore, the shift fork body cooperates with the high and low gear sleeves, and the shift fork body moves the high and low gear sleeves axially to engage with the input shaft connecting teeth or planetary carrier connecting teeth inside the housing.

[0008] Furthermore, a shift fork insert is mounted on the arc-shaped surface of the shift fork body, and the shift fork insert is disposed in an annular groove on the outer surface of the high and low gear sleeve.

[0009] Furthermore, one end of the buffer spring mounting seat extends outward and is provided with a roller. The roller is rolled on the helical track of the shift camshaft, which is arranged parallel to the bottom of the shift guide shaft and is connected to the motor sub-assembly.

[0010] Furthermore, the extension of the buffer spring mounting base has an opening and is provided with a roller mounting base, the roller shaft is mounted on the roller mounting base, and a roller retaining ring is provided at the bottom step of the roller shaft.

[0011] Furthermore, the spiral track on the shift camshaft unfolds into a stepped shape.

[0012] Furthermore, the roller and the shift camshaft are in clearance fit, and the contact surface between the roller and the spiral track is an arc surface. When the shift camshaft rotates, the roller rolls on its spiral track, driving the HL shift fork subassembly to move left and right.

[0013] Furthermore, the shift guide shaft, circular hole one, circular hole two, and circular hole three are arranged coaxially.

[0014] A shift buffer method for an electronically controlled transfer case, employing the aforementioned shift buffer mechanism of the electronically controlled transfer case, comprises the following steps: During normal gear shifting, the high and low gear sleeves move axially with the shift camshaft to switch between high and low gears. When the high and low gear sleeves are temporarily unable to complete the shifting action due to the top tooth, the shift camshaft will still rotate with the motor sub-assembly. The buffer spring mounting seat of the HL shift fork sub-assembly moves along the axis of the shift guide shaft along the helical track on the shift camshaft. At this time, the HL shift fork cannot reach the specified position because the high and low gear sleeves cannot complete the shifting action. The buffer spring is compressed by the buffer spring mounting seat and stores kinetic energy. As the planetary carrier connecting teeth or input shaft connecting teeth rotate, the top tooth problem disappears, the compressed buffer spring releases the stored kinetic energy, and the HL shift fork is pushed by the buffer spring to reach the specified position to complete the shifting action.

[0015] Furthermore, the specific steps are as follows: During normal gear shifting, the high and low gear sleeves move axially with the rotation of the shift camshaft. The HL shift fork sub-assemblies respectively cooperate with the input shaft connecting teeth or planetary carrier connecting teeth inside the housing to realize the high and low gear shifting function. When shifting from a high gear to a low gear, if the high-low gear sleeve cannot complete the shifting action temporarily due to the top tooth, the shift camshaft will rotate with the motor sub-assembly. The buffer spring mounting seat in the HL shift fork sub-assembly moves to the right along the axis of the shift guide shaft with the helical track on the shift camshaft. The buffer spring baffle on the left side of the buffer spring mounting seat transmits power to the buffer spring through the buffer spring positioning plate on the left side. At this time, the HL shift fork cannot reach the specified position because the high-low gear sleeve cannot complete the normal meshing with the planetary carrier connecting teeth. The buffer spring positioning plate on the right side of the buffer spring cannot move, causing the buffer spring to be compressed and store energy. As the planetary carrier connecting teeth rotate, the top tooth problem disappears, the compressed buffer spring releases the stored energy, and the HL shift fork is pushed to the specified position by the buffer spring to complete the shifting action. When shifting from a low gear to a high gear, if the high / low gear sleeve cannot complete the shifting action temporarily due to the top tooth, the shift camshaft will rotate with the motor sub-assembly. The buffer spring mounting seat in the HL shift fork sub-assembly moves to the left along the axis of the shift guide shaft along the helical track on the shift camshaft. The buffer spring baffle on the right side of the buffer spring mounting seat transmits power to the buffer spring through the buffer spring positioning plate on the right side. At this time, the HL shift fork cannot reach the specified position because the high / low gear sleeve cannot complete the normal meshing with the input shaft connecting teeth. The buffer spring positioning plate on the left side of the buffer spring cannot move, causing the buffer spring to be compressed and store energy. As the input shaft connecting teeth rotate, the top tooth problem disappears, the compressed buffer spring releases the stored energy, and the HL shift fork is pushed by the buffer spring to reach the specified position to complete the shifting action.

[0016] The beneficial effects of this invention are: simple structure, easy to process and manufacture and subsequent assembly; the buffer structure is placed in the HL shift fork sub-assembly, which has no impact on the external space of the housing and does not require high installation space; when the shifting action cannot be completed temporarily due to the top teeth or other reasons during high and low gear switching, the buffer spring stores and releases kinetic energy, and achieves delayed shifting without affecting the motor sub-assembly, thereby improving the performance of the transfer case. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention; Figure 2 This is a schematic diagram of the shift camshaft according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the shift guide shaft according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the high and low gear sleeves according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the HL shift fork sub-assembly according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the overall structure when switching to a lower gear according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the overall structure when switching to a higher gear according to an embodiment of the present invention; Figure 8 This is a schematic diagram of the unfolded spiral track on the shift camshaft according to an embodiment of the present invention; Figure 9 This is a schematic diagram of the buffer spring mounting base structure according to an embodiment of the present invention; Figure 10 This is a schematic diagram of the HL shift fork structure according to an embodiment of the present invention; Figure 11 This is a schematic diagram illustrating the application state of an embodiment of the present invention; In the diagram: 1. Shift camshaft, 1-1. Helical rail, 2. Shift guide shaft, 3. HL shift fork, 3-1. Shift fork body, 3-2. Mounting plate 2, 3-3. Circular hole 2, 3-4. Buffer spring baffle 2, 3-5. Semicircular hole 2, 3-6. Buffer spring mounting seat moving chamber, 3-7. Circular hole 3, 4. Buffer spring mounting seat, 5. Circular hole 1, 5-2. Semicircular hole 1, 5-3. Mounting plate 1, 5-4. Roller mounting seat, 5-5. Buffer spring, 6. Buffer spring positioning piece, 7. Roller, 8. Roller retaining ring, 9. High and low gear sleeve, 10. Annular groove, 10-1. External tooth, 10-2. Shift fork insert, 11. Input shaft connecting tooth, 12. Planetary carrier connecting tooth, 13. Buffer spring mounting chamber, 14. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments: This embodiment provides a shift buffer mechanism for an electronically controlled transfer case, comprising a shift camshaft 1, an HL shift fork subassembly, a shift guide shaft 2, and a high / low gear sleeve 10. The shift camshaft 1 and the shift guide shaft 2 are arranged in parallel inside the housing. The shift camshaft 1 is connected to a motor subassembly outside the housing, and a helical track 1-1 is provided on the cam of the shift camshaft 1.

[0019] See attached document Figure 1 , 5 11, the HL shift fork sub-assembly includes an HL shift fork 3, a buffer spring mounting base 5, a buffer spring 6, a buffer spring positioning plate 7, and a roller 8. The top of the buffer spring mounting base 5 is open, and both ends of the buffer spring mounting base 5 are provided with mounting plates 5-3. The mounting plates 5-3 have round holes 5-1. Two buffer spring baffles 5-4 are provided in the middle of the buffer spring mounting base 5. The buffer spring baffles 5-4 have semi-circular holes 5-2. One end of the buffer spring mounting base 5 extends outward and is provided with a roller 8. The roller 8 is rolled on the spiral track 1-1. The HL shift fork 3 includes a shift fork body 3-1 and a base 3-2. The shift fork body 3-1 cooperates with the high and low gear sleeve 10. A shift fork insert 11 is mounted on the arc-shaped surface of the shift fork body 3-1. The shift fork insert 11 is set in an annular groove 10-1 on the outer surface of the high and low gear sleeve 10. The shift fork body 3-1 moves the high and low gear sleeve 10 axially and engages with the input shaft connecting tooth 12 or the planetary carrier connecting tooth 13 inside the housing. The bottom of the base 3-2 is open. Mounting plates 3-3 are provided at both ends of the base 3-2. The space between the two mounting plates 3-3 forms a buffer spring mounting seat moving chamber 3-7. The buffer spring mounting seat 5 is set in the buffer spring mounting seat moving chamber 3-7 and can move left and right. A circular hole 3-4 is opened on the mounting plate 3-3. Two buffer spring baffles 3-5 are set in the middle of the mounting plate 3-3. A semi-circular hole 3-6 is opened on the buffer spring baffle 3-5. The HL shift fork 3 and the buffer spring mounting base 5 are arranged vertically opposite each other. The semi-circular hole 2 3-6 and the semi-circular hole 1 5-2 are vertically corresponding to form a complete circular hole 3 4. The shift guide shaft 2 passes through the circular hole 1 5-1, the circular hole 2 3-4 and the circular hole 3 4 and is assembled with the HL shift fork sub-assembly. The two buffer spring baffles 3-5 correspond vertically to the two buffer spring baffles 5-4, respectively, and the space between them forms a buffer spring mounting chamber 14. Buffer spring 6 is equipped with buffer spring positioning pieces 7 at both ends and is mounted on the shift guide shaft 2 inside the buffer spring mounting chamber 14. The upper parts of the two buffer spring positioning pieces 7 are in contact with the two buffer spring baffles 3-5, respectively, and the lower parts of the two buffer spring positioning pieces 7 are in contact with the two buffer spring baffles 5-4, respectively.

[0020] The shift guide shaft 2, the first round hole 5-1, the second round hole 3-4 and the third round hole 4 are arranged coaxially.

[0021] See attached document Figure 2 A cam is provided in the middle of the shift camshaft 1, and a spiral track 1-1 is provided on the outer ring surface of the cam. When the motor sub-assembly provides power, the shift camshaft 1 rotates around its own axis.

[0022] See attached document Figure 3 The shift guide shaft 2 is used to assemble the HL shift fork subassembly into the housing.

[0023] See attached document Figure 4 The high and low gear sleeve 10 has an annular groove 10-1 and an external tooth 10-2 at both ends. The annular groove 10-1 cooperates with the shift fork insert 11 on the shift fork body 3-1, and the external tooth 10-2 cooperates with the input shaft connecting tooth 12 and the planetary carrier connecting tooth 13 respectively.

[0024] See attached document Figure 5Both ends of the buffer spring 6 are equipped with buffer spring positioning plates 7, which are compressed and installed in the buffer spring mounting chamber 14. This gives the buffer spring a certain elastic potential energy, and when the buffer spring mounting seat 5 moves, it can transmit power to the buffer spring 6 through the buffer spring positioning plate 7 on one side, then to the buffer spring positioning plate 7 on the other side, and finally to the HL shift fork 3. Power is transmitted to the HL shift fork 3 through the internal buffer spring 6 and the buffer spring positioning plates 7 at both ends. The HL shift fork 3 drives the high and low gear sleeve 10 to move axially, changing the engagement between the high and low gear sleeve 10 and the input shaft connecting gear 12 or the planetary carrier connecting gear 13, thus realizing the switching of high and low gears.

[0025] See attached document Figure 5 During normal gear shifting, the high and low gear sleeve 10 moves axially with the shift camshaft 1 to achieve high and low gear shifting function.

[0026] See attached document Figure 6 When shifting from a high gear to a low gear, if the high / low gear sleeve 10 cannot complete the shifting action temporarily due to issues such as tooth tipping, the shift camshaft 1 will rotate with the motor sub-assembly. The buffer spring mounting seat 5 in the HL shift fork sub-assembly moves to the right along the axis of the shift guide shaft with the helical track 1-1 on the shift camshaft 1. The buffer spring baffle 5-4 on the left side of the buffer spring mounting seat 5 transmits power to the buffer spring 6 through the buffer spring positioning plate 7 on the left side. At this time, the HL shift fork 3 cannot reach the specified position because the high / low gear sleeve 10 cannot complete the normal meshing with the planetary carrier connecting tooth 13. The buffer spring positioning plate 7 on the right side of the buffer spring 6 is blocked by the buffer spring baffle 3-5 on the right side and cannot move, causing the buffer spring 6 to be compressed and store energy. As the planetary carrier connecting tooth 13 rotates, the issues such as tooth tipping between the high / low gear sleeve 10 and the planetary carrier connecting tooth 13 disappear, the compressed buffer spring 6 releases the stored energy, and the HL shift fork 3 reaches the specified position and completes the shifting action.

[0027] See attached document Figure 7When shifting from a low gear to a high gear, if the high / low gear sleeve 10 cannot complete the shifting action temporarily due to issues such as tooth tipping, the shift camshaft 1 will rotate with the motor sub-assembly. The buffer spring mounting seat 5 in the HL shift fork sub-assembly moves to the left along the axis of the shift guide shaft 2 along the spiral track 1-1 on the shift camshaft 1. The buffer spring baffle 5-4 on the right side of the buffer spring mounting seat 5 transmits power to the buffer spring 6 through the buffer spring positioning plate 7 on the right side. At this time, the HL shift fork 3 cannot reach the specified position because the high / low gear sleeve 10 cannot complete the normal meshing with the input shaft connecting tooth 12. The buffer spring positioning plate 7 on the left side of the buffer spring 6 cannot move due to the obstruction of the buffer spring baffle 3-5 on the left side, causing the buffer spring 6 to be compressed and store energy. As the input shaft connecting tooth 12 rotates, the issues such as tooth tipping between the high / low gear sleeve 10 and the input shaft connecting tooth 12 disappear, the compressed buffer spring 6 releases the stored energy, and the HL shift fork 3 reaches the specified position and completes the shifting action.

[0028] The above technical solution enables delayed gear shifting during normal operation of the external motor subassembly. This reduces the number of individual components, optimizes the overall structure, simplifies and speeds up assembly, and improves efficiency.

[0029] See attached document Figure 8 The spiral track 1-1 on the shift camshaft 1 unfolds into a stepped shape.

[0030] See attached document Figure 9 The buffer spring mounting base 5 is a semi-cylindrical structure with an open upper part. Two parallel annular mounting plates 5-3 are provided at both ends. The inner hole of the mounting plate 5-3 is a circular hole 5-1. Two parallel semi-annular buffer spring baffles 5-4 are provided in the middle of the buffer spring mounting base 5. The inner hole of the buffer spring baffle 5-4 is a semi-circular hole 5-2. The right end of the buffer spring mounting base 5 extends outward and has a through hole. A roller mounting base 5-5 is provided at the through hole. The roller mounting base 5-5 has a cylindrical cavity structure. The roller 8 includes a shaft and a roller body rotatably mounted on the shaft. The roller body and the buffer spring mounting base 5 are clearance-fitted to ensure smooth rotation of the roller 8 on the buffer spring mounting base 5. The shaft of the roller 8 is mounted on the roller mounting base 5-5 and fastened with screws or other fasteners. A roller retaining ring 9 is provided at the bottom step of the shaft of the roller 8 to prevent the roller body from falling off.

[0031] See attached document Figure 10The HL shift fork 3 includes a shift fork body 3-1 and a base 3-2. The shift fork body 3-1 cooperates with the high and low gear sleeve 10. The base 3-2 is a semi-cylindrical structure with an open bottom. Two parallel annular mounting plates 3-3 are provided at both ends of the base 3-2. The space between the two mounting plates 3-3 forms a buffer spring mounting seat moving chamber 3-7. The buffer spring mounting seat 5 is set in the buffer spring mounting seat moving chamber 3-7 and can move left and right. The inner hole of the mounting plate 3-3 is a circular hole 3-4. Two parallel semi-annular buffer spring baffles 3-5 are provided in the middle of the base 3-2. The inner hole of the buffer spring baffles 3-5 is a semi-circular hole 3-6.

[0032] The mounting plate 5-3 and the buffer spring baffle 5-4 of the buffer spring mounting base 5 are both located in the movable chamber 3-7 of the buffer spring mounting base, and the extension of the buffer spring mounting base 5 is located below the base 3-2.

[0033] The above is merely one embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made on the basis of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A shift buffer mechanism for an electronically controlled transfer case, comprising an HL shift fork subassembly disposed on a shift guide shaft (2), characterized in that: The HL shift fork subassembly includes an HL shift fork (3), a buffer spring mounting base (5), a buffer spring (6), and a buffer spring positioning plate (7). The top of the buffer spring mounting base (5) is open, and mounting plates (5-3) are provided at both ends of the buffer spring mounting base (5). A circular hole (5-1) is opened on the mounting plate (5-3). Two buffer spring baffles (5-4) are provided in the middle of the buffer spring mounting base (5). A semi-circular hole (5-2) is opened on the buffer spring baffle (5-4). The HL shift fork (3) includes a fork body (3-1) and a base (3-2). The bottom of the base (3-2) is open, and mounting plates (3-3) are provided at both ends of the base (3-2). The space between the two mounting plates (3-3) forms a buffer spring mounting seat moving chamber (3-7). The buffer spring mounting seat (5) is set in the buffer spring mounting seat moving chamber (3-7) and can move left and right. The mounting plate (3-3) has a round hole (3-4). The base (3-2) has two buffer spring baffles (3-5) in the middle. The buffer spring baffles (3-5) have a semi-circular hole (3-6). The HL shift fork (3) and the buffer spring mounting base (5) are arranged opposite each other, and the semi-circular hole two (3-6) and the semi-circular hole one (5-2) are arranged opposite each other to form a complete circular hole three (4). The shift guide shaft (2) passes through the circular hole one (5-1), the circular hole two (3-4) and the circular hole three (4) and is assembled with the HL shift fork sub-assembly. The two buffer spring baffles (3-5) correspond vertically to the two buffer spring baffles (5-4) respectively, and the space between them forms a buffer spring mounting chamber (14). The buffer spring (6) is equipped with buffer spring positioning pieces (7) at both ends and is mounted on the shift guide shaft (2) in the buffer spring mounting chamber (14). The upper parts of the two buffer spring positioning pieces (7) are in contact with the two buffer spring baffles (3-5) respectively, and the lower parts of the two buffer spring positioning pieces (7) are in contact with the two buffer spring baffles (5-4) respectively.

2. The shift buffer mechanism of an electronically controlled transfer case according to claim 1, characterized in that: The shift fork body (3-1) cooperates with the high and low gear sleeve (10). The shift fork body (3-1) moves the high and low gear sleeve (10) axially to mesh with the input shaft connecting teeth (12) or planetary carrier connecting teeth (13) inside the housing.

3. The shift buffer mechanism of an electronically controlled transfer case according to claim 2, characterized in that: The fork body (3-1) is equipped with a fork insert (11) on its arc-shaped surface. The fork insert (11) is located in an annular groove (10-1) on the outer surface of the high and low gear sleeve (10).

4. The shift buffer mechanism of an electronically controlled transfer case according to claim 2, characterized in that: One end of the buffer spring mounting base (5) extends outward and is provided with a roller (8). The roller (8) is rolled on the spiral track (1-1) of the shift camshaft (1). The shift camshaft (1) is arranged parallel to the bottom of the shift guide shaft (2). The shift camshaft (1) is connected to the motor sub-assembly.

5. The shift buffer mechanism of an electronically controlled transfer case according to claim 4, characterized in that: The extension of the buffer spring mounting base (5) has an opening and is provided with a roller mounting base (5-5). The shaft of the roller (8) is mounted on the roller mounting base (5-5), and a roller retaining ring (9) is provided at the bottom step of the shaft of the roller (8).

6. The shift buffer mechanism of an electronically controlled transfer case according to claim 4, characterized in that: The spiral track (1-1) on the shift camshaft (1) unfolds into a stepped shape.

7. The shift buffer mechanism of an electronically controlled transfer case according to claim 4, characterized in that: The roller (8) is clearance-fitted with the shift camshaft (1), and the contact surface between the roller (8) and the spiral track (1-1) is an arc surface. When the shift camshaft (1) rotates, the roller (8) rolls on its spiral track (1-1), driving the HL shift fork subassembly to move left and right.

8. The shift buffer mechanism of an electronically controlled transfer case according to claim 4, characterized in that: The shift guide shaft (2), the first round hole (5-1), the second round hole (3-4) and the third round hole (4) are arranged coaxially.

9. A shift buffer method for an electronically controlled transfer case, employing the shift buffer mechanism of the electronically controlled transfer case as described in any one of claims 4-8, characterized in that... The following steps are required: During normal gear shifting, the high and low gear sleeve (10) moves axially with the shift camshaft (1) to achieve high and low gear switching. When the high and low gear sleeve (10) cannot complete the shifting action temporarily due to the top tooth, the shift camshaft (1) will still rotate with the motor sub-assembly. The buffer spring mounting seat (5) of the HL shift fork sub-assembly moves along the axis of the shift guide shaft (2) with the spiral track (1-1) on the shift camshaft (1). At this time, the HL shift fork (3) cannot reach the specified position because the high and low gear sleeve (10) cannot complete the shifting action. The buffer spring (6) is compressed by the buffer spring mounting seat (5) and stores kinetic energy. As the planetary carrier connecting tooth (13) or the input shaft connecting tooth (12) rotates, the top tooth problem disappears, the compressed buffer spring (6) releases the stored kinetic energy, and the HL shift fork (3) is pushed by the buffer spring (6) to reach the specified position to complete the shifting action.

10. A shifting buffer method for an electronically controlled transfer case according to claim 9, characterized in that... The specific steps are as follows: During normal gear shifting, the high and low gear sleeves (10) move axially as the shift camshaft (1) rotates. The HL shift fork sub-assemblies are respectively engaged with the input shaft connecting teeth (12) or planetary carrier connecting teeth (13) inside the housing to realize the high and low gear shifting function. When shifting from a high gear to a low gear, if the high-low gear sleeve (10) is temporarily unable to complete the shifting action due to the top tooth, the shift camshaft (1) will rotate with the motor sub-assembly. The buffer spring mounting seat (5) in the HL shift fork sub-assembly moves to the right along the axis of the shift guide shaft (2) along the spiral track (1-1) on the shift camshaft (1). The buffer spring baffle (5-4) on the left side of the buffer spring mounting seat (5) transmits the power to the buffer through the buffer spring positioning plate (7) on the left side. Spring (6), at this time, the HL shift fork (3) cannot reach the specified position because the high and low gear sleeve (10) cannot complete the normal meshing with the planetary carrier connecting tooth (13). The buffer spring positioning piece (7) on the right side of the buffer spring (6) cannot move, causing the buffer spring (6) to be compressed and store energy. As the planetary carrier connecting tooth (13) rotates, the top tooth problem disappears, the compressed buffer spring (6) releases the stored energy, and the HL shift fork (3) is pushed by the buffer spring (6) to reach the specified position to complete the shifting action. When shifting from a low gear to a high gear, if the high / low gear sleeve (10) is temporarily unable to complete the shifting action due to the top tooth, the shift camshaft (1) will rotate with the motor sub-assembly. The buffer spring mounting seat (5) in the HL shift fork sub-assembly moves to the left along the axis of the shift guide shaft (2) along the spiral track (1-1) on the shift camshaft (1). The buffer spring baffle (5-4) on the right side of the buffer spring mounting seat (5) transmits the power to the buffer spring through the buffer spring positioning plate (7) on the right side. Spring (6), at this time, the HL shift fork (3) cannot reach the specified position because the high and low gear sleeve (10) cannot complete the normal meshing with the input shaft connecting tooth (12). The buffer spring positioning piece (7) on the left side of the buffer spring (6) cannot move, causing the buffer spring (6) to be compressed and store energy. As the input shaft connecting tooth (12) rotates, the top tooth problem disappears, the compressed buffer spring (6) releases the stored energy, and the HL shift fork (3) is pushed by the buffer spring (6) to reach the specified position to complete the shifting action.

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