Gear shift transmission device, design method thereof, electric drive axle and gear shift method

Abstract

This invention discloses a gear shifting transmission device, an electric drive axle, a design method for the gear shifting transmission device, and a gear shifting method. The gear shifting transmission device includes: a first transmission member, including a first tooth, a first groove, and a clearance groove; at least one shift gear, including a coupling structure, the coupling structure including a wheel body and multiple coupling teeth; a second transmission member, including multiple second teeth and at least one limiting block located between two adjacent second teeth. Along the circumference of the second transmission member, the width of the limiting block is not less than the width shared by the two adjacent second teeth. Along the radial direction of the second transmission member, the limiting block spans the root circle of the multiple coupling teeth. Each second tooth is disposed in a first groove, and a limiting block is disposed in a clearance groove and slides with the clearance groove. The second transmission member has a first state in which the second teeth simultaneously mesh with the first teeth and the coupling teeth, and a second state in which the second teeth only mesh with the first teeth and not with the coupling teeth.

Description

Technical Field

[0001] This invention relates to the field of gear shifting technology for new energy vehicles, and particularly to a gear shifting device, an electric drive axle, a design method for the gear shifting device, and a gear shifting method. Background Technology

[0002] In the gearbox or electric drive axle shifting systems of new energy vehicles, the shift engagement sleeve is typically used for position calibration during shift self-learning and for limiting the gear position after shifting. In existing shifting structures, to ensure stable gear positions and prevent disengagement after shifting, the spline between the engagement sleeve and the shift gear often employs a bevel gear structure. When the shift is complete and the drive motor resumes torque, the bevel gear structure decomposes the transmitted torque into an axial force. This axial force drives the engagement sleeve to continuously move towards the shift gear, improving the shift success rate.

[0003] However, if the axial movement of the engagement sleeve is not effectively limited, it will continuously move towards the shift gear under sustained axial force, leading to uncontrolled shifting and even interference or collision between the engagement sleeve and the gear structure, severely affecting shifting reliability and system lifespan. Therefore, a dedicated limiting structure must be installed to constrain the endpoint of the engagement sleeve's axial movement. Summary of the Invention

[0004] The purpose of this invention is to provide a gear shifting device, an electric drive axle, a design method for the gear shifting device, and a gear shifting method, which can provide stable and effective limiting during gear shifting and achieve reliable gear shifting.

[0005] The first aspect of this invention discloses a gear shifting and transmission device, comprising: The first transmission component includes a plurality of first teeth arranged circumferentially thereon, a first groove extending axially between two adjacent first teeth, and a clearance groove between two adjacent first teeth. At least one shift gear includes a engagement structure, the engagement structure including a wheel body and a plurality of engagement teeth evenly arranged circumferentially along the wheel body; The second transmission member, used to transmit torque in transmission cooperation with the first transmission member and the connecting structure, includes a plurality of second teeth evenly arranged circumferentially and at least one limiting block located between two adjacent second teeth. Along the circumferential direction of the second transmission member, the width of the limiting block is not less than the width shared by two adjacent second teeth. Along the radial direction of the second transmission member, the limiting block spans the root circle of the plurality of connecting teeth. Each second tooth is disposed within a first groove and slidably engages with the first groove. A limiting block is disposed within a clearance groove and slidably engages with the clearance groove. The second transmission member has a first state in which the second teeth simultaneously engage with the first teeth and the connecting teeth, and a second state in which the second teeth only engage with the first teeth and not with the connecting teeth. The second transmission member switches between the first and second states by sliding the second teeth relative to the first groove and by sliding the limiting block relative to the clearance groove.

[0006] In some embodiments, the second transmission member includes an annular meshing sleeve, the second tooth and the limiting block are located on the inner wall of the meshing sleeve, the at least one shift gear includes two shift gears located on both sides of the second transmission member, the limiting block is disposed in the middle of the inner wall of the meshing sleeve along the axial direction, the two end faces of the limiting block along the circumference of the second transmission member are continuous surfaces in the axial direction, and one of the two end faces meshes with the first tooth in a first state.

[0007] In some embodiments, the two end faces of the limiting block along the axial direction are limiting planes, and the end face of the wheel body near the meshing sleeve along the axial direction is a plane. In the second state, the limiting plane is in contact with the end face of the wheel body along the axial direction.

[0008] In some embodiments, the second transmission member includes a plurality of limiting blocks evenly arranged along its circumference.

[0009] In some embodiments, the second tooth along the axial direction includes a straight tooth located in the middle for meshing with the first tooth and bevel teeth located at both ends for meshing with the engagement tooth. The two end faces of the limiting block along the circumference of the second transmission member are surfaces for meshing with the first tooth. Along the circumference of the second transmission member, an axially extending transmission groove is formed between the limiting block and two adjacent second teeth for insertion of the first tooth and the engagement tooth. The transmission groove is provided with a first chamfer connecting the bevel tooth and the straight tooth. The first chamfer crosses the limiting plane along the axial direction.

[0010] In some embodiments, a second chamfer is provided between the end of the limiting plane and the inner wall of the engaging sleeve, the second chamfer being a rounded corner.

[0011] In some embodiments, the radially inner end face of the limiting block is an arc surface coaxial with the second transmission member.

[0012] In some embodiments, an end face chamfer is provided at one end of the engaging tooth near the second transmission member along the axial direction. The end face chamfer is used to guide the second tooth when switching from the second state to the first state. Along the radial direction of the shift gear, the starting profile of the end face chamfer is located on the root circle of the plurality of engaging teeth.

[0013] A second aspect of the present invention discloses an electric drive axle, including any of the aforementioned gear shifting and transmission devices.

[0014] A third aspect of this invention discloses a design method for any of the aforementioned gear shifting and transmission devices, comprising: Obtain the maximum axial resultant force F transmitted by the gear shifting device when it is in the first state; The thickness of the limiting block along the axial direction is determined based on the axial resultant force F, such that the maximum stress value of the limiting block under the action of the axial resultant force F is less than one-third of the yield strength of the limiting block material.

[0015] In some embodiments, the second tooth along the axial direction includes a straight tooth located in the middle for meshing with the first tooth and bevel teeth located at both ends for meshing with the engagement tooth. The design method of the gear shifting device includes: When manufacturing the second tooth, a long straight tooth is first drawn out using a broach, and then the two ends of the long straight tooth are squeezed to form the conical tooth using a cone-shaped extrusion method.

[0016] A fourth aspect of the present invention discloses a gear shifting method, employing any of the aforementioned gear shifting and transmission devices, wherein the at least one shift gear includes two shift gears located on both sides of the second transmission member, and the gear shifting method includes: Shift self-learning steps: Drive the second transmission component to move axially to one side until the limiting block contacts the end face of the shift gear on that side, and record this position as the first limiting position; then drive the second transmission component to move axially to the other side until the limiting block contacts the end face of the shift gear on the other side, record this position as the second limiting position, and determine the neutral position based on the first limiting position and the second limiting position.

[0017] In some embodiments, the neutral position is the midpoint between the first limiting position and the second limiting position.

[0018] In some embodiments, the method further includes a shifting step: setting a position L away from the first limiting position along the direction close to the second transmission member as a first target position, and setting a position L away from the second limiting position along the direction close to the second transmission member as a second target position; when the second transmission member moves to the shift gear at the first limiting position to shift gear, the second transmission member is driven to move from the neutral position to the first target position and then stops; then the second transmission member continues to move under the axial force of the second tooth until the limiting block reaches the first limiting position; when the second transmission member moves to the shift gear at the second limiting position to shift gear, the second transmission member is driven to move from the neutral position to the second target position and then stops; then the second transmission member continues to move under the axial force of the second tooth until the limiting block reaches the second limiting position.

[0019] Based on the gear shifting device provided by the present invention, a limiting block with a circumferential width of not less than the width shared by two adjacent second teeth is provided on the second transmission member, and the limiting block spans the root circle of multiple engaging teeth along the radial direction of the second transmission member. This ensures that when the second transmission member engages with the shift gear, the limiting block will not be inserted into the tooth groove between the engaging teeth, and the limiting block will contact and limit the end face of the wheel body, thereby achieving reliable limiting of the second transmission member.

[0020] Other features and advantages of the invention will become clear from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. Attached Figure Description

[0021] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings: Figure 1 This is a cross-sectional view of the gear shifting and transmission device according to an embodiment of the present invention; Figure 2 for Figure 1 A schematic diagram of the structure of the first transmission component of the gear shifting and transmission device shown. Figure 3 for Figure 1 A schematic diagram of the structure of the second transmission component of the gear shifting and transmission device shown; Figure 4 for Figure 3 A partially enlarged structural diagram of part K of the structure shown; Figure 5 for Figure 1 The diagram shows the structure of the shift gears in the gear shifting device. Figure 6 for Figure 5A partially enlarged schematic diagram of part A of the structure shown. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0024] In the description of this invention, it should be understood that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0025] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0026] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0027] like Figures 1 to 6 As shown, the gear shifting device in this embodiment includes a first transmission component 1, at least one shift gear 3, and a second transmission component 2.

[0028] The first transmission member 1 includes a plurality of first teeth 11 arranged circumferentially thereon, a first groove 12 extending axially between two adjacent first teeth 11, and a clearance groove 13 between two adjacent first teeth 11. In the embodiment shown in the figure, the first transmission member is used to input power, and then the first transmission member transmits the power to the second transmission member 2, the second transmission member 2 then transmits the power to the shift gear 3 that meshes with it, and then the shift gear 3 outputs the power downstream. In some embodiments not shown in the figure, the shift gear 3 may also input power, then transmit it to the first transmission member through the second transmission member, and then output it through the first transmission member.

[0029] like Figure 1 , Figure 5 and Figure 6 As shown, the shift gear 3 includes a coupling structure, which comprises a wheel body 31 and a plurality of coupling teeth 32 evenly arranged along the circumference of the wheel body 31. The coupling structure of the shift gear 3 is used to engage with the second transmission component to transmit power. The shift gear includes a coupling structure and a transmission gear that are fixedly connected to each other along the axial direction. During transmission, the second transmission component transmits power to the coupling structure through the meshing coupling teeth, and then the coupling structure transmits the power to the transmission gear, whose teeth then output the power. The coupling teeth 32 on the coupling structure are typically splined teeth.

[0030] The second transmission member 2 is used to transmit torque in transmission cooperation with the first transmission member 1 and the connecting structure. The second transmission member 2 includes a plurality of second teeth 21 evenly arranged along its circumference and at least one limiting block 22 located between two adjacent second teeth 21. Each second tooth 21 of the second transmission member is disposed in a first groove 12 and slides in cooperation with the first groove 12. In the embodiment shown in the figure, the first teeth are splined teeth, and a first groove is formed between two first teeth. The second teeth 21 are also splined teeth and can slide in the first groove, thereby realizing the axial movement of the second transmission member to achieve engagement or disengagement of the gear shifting gear.

[0031] In existing gear shifting structures, to ensure stable gear shifting and prevent disengagement, the spline between the engagement sleeve and the shift gear often employs a bevel gear structure. When the shift is complete and the drive motor resumes torque, the bevel gear structure decomposes the transmitted torque into an axial force. This axial force drives the engagement sleeve to continuously move towards the shift gear, improving the shift success rate. The second tooth and the engagement tooth of the shift gear in this application also adopt this design. When the second tooth engages with the engagement tooth, and torque is transmitted between them, the engagement tooth generates an axial force on the second tooth, causing the second transmission component to tend to move axially towards the shift gear. In the embodiment shown in the figure, the parts where the second tooth and the engagement tooth mesh are both bevel gear structures.

[0032] In this embodiment, the width of the circumferential limiting block 22 along the second transmission member 2 is not less than the width shared by two adjacent second teeth 21, that is, along a circle coaxial with the second transmission member, typically using the root circle of the second tooth as this circle. The width of the limiting block 22 is greater than or equal to the width shared by two adjacent second teeth 21. The width shared by two adjacent second teeth refers to the width of the structure including the two adjacent second teeth themselves and the tooth groove between them, that is, the width defined by the two outermost contour lines of the two adjacent second teeth along the circumference of the second transmission member 2. Therefore, the limiting block of this embodiment can be manufactured based on the fabrication of two adjacent second teeth blanks joined together, producing a limiting block with a width greater than or equal to the width of two adjacent second teeth 21.

[0033] Along the radial direction of the second transmission member 2, the limiting block 22 spans the root circles of multiple engaging teeth 32, meaning the limiting block passes through the root circles of the engaging teeth 32. Part of the limiting block's structure is located on one side of the root circle, and another part is located on the other side. In the embodiment shown, where the second transmission member is a gear ring structure, the limiting block extends radially inward from the inner wall of the second transmission member, and the engaging teeth extend radially outward from the outer circumference of the wheel body, the diameter of the limiting block's tip circle is smaller than the diameter of the engaging tooth root circle of the engaging teeth 32. That is, in this embodiment, the limiting block cannot be inserted into the tooth groove between two adjacent engaging teeth, while the second tooth, along the radial direction of the second transmission member 2, does not span the root circles of multiple engaging teeth 32, and can be inserted into the tooth groove between two adjacent engaging teeth to mesh normally with them. That is, the length of the radial limiting block along the second transmission component 2 is longer than the second tooth, and the length of the second tooth along the axial direction is longer than the length of the limiting block. When the engaging tooth is inserted between two adjacent second teeth in the axial direction, the limiting tooth corresponding to the limiting block can be inserted to the end face of the limiting block along the axial direction. In the axial direction, the limiting block does not interfere with the engagement between the engaging tooth and the second tooth. Thus, when the second tooth meshes with the engaging tooth of the shift gear, the limiting block can contact the end face of the wheel body of the engaging structure for limiting.

[0034] A limiting block 22 is disposed within a clearance groove 13 and slides within the clearance groove 13. Since the length of the limiting block along the radial direction of the second transmission member 2 is longer than the second tooth, such as... Figure 2 As shown, the depth of the clearance groove 13 is deeper than that of the first groove 12.

[0035] The second transmission member 2 has a first state in which the second tooth 21 simultaneously meshes with the first tooth 11 and the engagement tooth 32, and a second state in which the second tooth 21 meshes only with the first tooth 11 and not with the engagement tooth 32. The second transmission member 2 switches between the first and second states by sliding the second tooth 21 relative to the first groove 12 and by sliding the limiting block 22 relative to the clearance groove 13. That is, in the first state, the second transmission member engages with the shift gear, and the second transmission member simultaneously drives the first transmission member and the shift gear. In the second state, the second transmission member does not drive the shift gear, but only drives the first transmission member, that is, the gear shifting device is in neutral.

[0036] In this embodiment, the gear shifting device has a limiting block 22 on the second transmission member 2 with a circumferential width not less than the width shared by two adjacent second teeth 21. The limiting block 22 spans the root circle of multiple engaging teeth 32 along the radial direction of the second transmission member 2. The limiting block is large in size and has high strength. When the second transmission member 2 is engaged with the shift gear 3, the limiting block 22 will not be inserted into the tooth groove between the engaging teeth 32. Under the action of the axial force between the engaging teeth and the second teeth, the limiting block 22 will contact the end face of the wheel body 31. The large-width limiting block has high strength and can withstand greater axial force, thus achieving reliable limiting of the second transmission member 2.

[0037] In some embodiments, such as Figure 1 , Figure 3 and Figure 4 As shown, the second transmission component 2 includes an annular meshing sleeve, with the second tooth 21 and the limiting block 22 located on the inner wall of the meshing sleeve. At least one shift gear 3 includes two shift gears 3 located on both sides of the second transmission component 2, as shown. Figure 1 In the illustrated embodiment, the two shift gears 3 are respectively the first gear and the second gear located on both sides of the second transmission member. The axial limiting block 22 is located in the middle of the inner wall of the meshing sleeve. That is, the size of the axial limiting block does not completely occupy the inner wall of the meshing sleeve. There is still space on both sides of the inner wall of the axial meshing sleeve. As shown in the figure, there are two grooves on both sides of the limiting block for the engagement teeth of the two shift gears to extend into. Specifically, when the second transmission member and a shift gear, such as the first gear, are engaged, the engagement teeth of the first gear corresponding to the limiting block extend into the grooves on the side of the limiting block, directly opposite the limiting block along the axial direction, thus not affecting the normal axial insertion of the engagement teeth and the second gear. The two end faces of the limiting block 22 along the circumference of the second transmission member 2 are continuous surfaces in the axial direction, as shown in the figure, and one of the two end faces engages with the first gear 11 in the first state. The two end faces of the circumferential limiting block are used for transmission with the first tooth. When the first transmission component rotates in different directions, the first tooth selects different end faces of the two end faces of the limiting block for engagement. In this embodiment, the two end faces of the circumferential limiting block are continuous surfaces with no breaks in the middle. The limiting block can transmit a larger torque with the first tooth, and the transmission effect is more reliable.

[0038] In some embodiments, the two end faces of the limiting block 22 along the axial direction are limiting planes 221, and the end face of the wheel body 31 near the meshing sleeve along the axial direction is a plane. In the second state, the limiting planes 221 are in contact with the end face of the wheel body 31 along the axial direction. Figure 1 and Figure 4 As shown, the limiting block 22 on the second transmission member 2 has an axial (i.e., Figure 1The two end faces (in the left and right directions) of the gear 3 are machined into flat planes. Simultaneously, the end face of the gear body 31 of the shift gear 3 near the meshing sleeve is also machined into a flat plane. When the shift gear is in the first state, the second transmission member 2 moves to one side under axial force, and the limiting plane 221 directly contacts the end face of the corresponding side shift gear 3's gear body 31, forming a surface-to-surface contact limiting. This embodiment, by designing the limiting surface as a planar contact, significantly reduces contact stress compared to point or line contact, avoiding local crushing or wear. Simultaneously, planar contact ensures uniform force distribution between the limiting block and the gear body when subjected to axial resultant force, resulting in stable and reliable limiting. Furthermore, planar machining is simple, easily ensuring flatness requirements, and facilitating simultaneous contact of multiple limiting blocks, improving the synchronization and reliability of the limiting.

[0039] In some embodiments, the second transmission member 2 includes a plurality of limiting blocks 22 evenly arranged circumferentially thereon. For example... Figure 3 and Figure 4 As shown, multiple limiting blocks 22, such as three, four, or six, are evenly arranged along the circumferential direction on the inner wall of the second transmission component 2 (the meshing sleeve shown in the figure). These limiting blocks are distributed at equal angles around the circumference. Correspondingly, the same number of clearance grooves 13 are also evenly arranged on the circumference of the first transmission component 1 (the gear seat in the embodiment shown in the figure), and each limiting block 22 slides into one clearance groove 13. In this embodiment, by setting multiple circumferentially distributed limiting blocks, the axial resultant force is distributed to the end faces of multiple limiting blocks after shifting, reducing the load borne by each limiting block, thereby reducing the stress level of a single limiting block and improving the fatigue life of the structure. At the same time, the even distribution ensures that the meshing sleeve is subjected to balanced force in the circumferential direction, avoiding tilting or jamming of the meshing sleeve due to uneven loading, making the limiting action smoother and more reliable. In addition, the common guidance of multiple limiting blocks also improves the straightness of the axial movement of the meshing sleeve.

[0040] In some embodiments, the axial second tooth 21 includes a straight tooth located in the middle for meshing with the first tooth 11 and bevel teeth located at both ends for meshing with the engagement tooth 32. The two end faces of the limiting block 22 along the circumference of the second transmission member 2 are surfaces for meshing with the first tooth 11. Along the circumference of the second transmission member 2, an axially extending transmission groove 23 is formed between the limiting block 22 and two adjacent second teeth 21 for insertion of the first tooth 11 and the engagement tooth 32. The transmission groove 23 is provided with a first chamfer 241 connecting the bevel tooth and the straight tooth, and the first chamfer 241 extends across the limiting plane 221 along the axial direction. Figure 4As shown, the second tooth 21 is divided into three segments along the axial direction: the middle segment is a straight tooth 212, whose tooth flank meshes with the first tooth 11 for transmission; the two ends are engaging bevel teeth 211, used to mesh with the engaging teeth 32 of the shift gear 3 for transmission. During transmission, the engaging bevel teeth 211 and the engaging teeth generate an axial component force through the conical surface. The two end faces 222 of the limiting block 22 along the circumferential direction are also designed as transmission surfaces, meshing with the tooth flank of the first tooth 11 and participating in torque transmission. Therefore, the limiting block 22 not only plays a limiting role but also undertakes part of the transmission function. In the circumferential direction, the limiting block 22 and the two adjacent second teeth 21 form an axially penetrating transmission groove 23, which is used to accommodate the insertion of the engaging teeth 32. A first chamfer 241 is provided on the side wall of the transmission groove 23. This first chamfer 241 connects the bevel tooth and the spur tooth, and its axial position crosses the limiting plane 221. Specifically, as shown in the figure, the distance between the starting contour line of the first chamfer 241 and the limiting plane 221 along the axial direction is S. The starting and ending contour lines of the first chamfer 241 along the axial direction are located on both sides of the limiting plane 221 of the limiting block. In this embodiment, by using the end face of the limiting block as the transmission surface, the tooth surface area for transmitting torque is increased, thereby improving the load-bearing capacity. The setting of the first chamfer ensures that the engaging tooth will not contact the second tooth or the limiting block in the axial direction when inserted, avoiding interference with the contact limiting of the limiting block and the wheel body in the axial direction, thus maintaining the reliability of the limiting while ensuring smooth transmission.

[0041] In some embodiments, a second chamfer 242 is further provided between the end of the limiting plane 221 and the inner wall of the engaging sleeve, and the second chamfer 242 is a rounded corner. Figure 4 As shown, a second chamfer 242 is provided at the end of the limiting plane 221 (i.e., at the junction of the limiting plane and the inner wall of the engagement sleeve). This second chamfer is in the form of a rounded corner. Since the limiting plane 221 bears a large axial impact load during operation, stress concentration easily occurs at its root (where it connects to the engagement sleeve body). This embodiment effectively reduces stress concentration by providing a rounded corner at this location, preventing the limiting block from breaking at its root under repeated impacts, and significantly improving the structural strength and fatigue life of the limiting block. At the same time, the rounded corner design facilitates processing and avoids potential damage from sharp edges.

[0042] In some embodiments, the radially inner end face of the limiting block 22 is an arc surface coaxial with the second transmission member 2. For example... Figure 4 As shown, the radially inner end face of the limiting block 22 (i.e., the face facing the axis of the second transmission member) is machined into an arc surface coaxial with the second transmission member 2. The arc surface design in this embodiment facilitates manufacturing and also helps to make the pressure on the limiting block more uniform during limiting.

[0043] In some embodiments, such as Figure 5 and Figure 6As shown, the end of the axially engaged tooth near the second transmission member has a chamfered end face. The chamfered end face guides the second tooth when switching from the second state to the first state. Along the radial direction of the shift gear, the starting contour line of the chamfered end face is located on the root circle of the plurality of engaged teeth. When engaging a gear, the second tooth may smoothly insert into the tooth groove between the two engaged teeth, or it may first contact the end face of the engaged tooth. In this embodiment, by setting the chamfered end face, when the engaged tooth contacts the chamfered end face, the chamfered end face provides a tangential force perpendicular to the radial direction to the second tooth, guiding the second tooth to rotate and smoothly insert it into the tooth groove, facilitating gear engagement. Meanwhile, since the starting contour line of the end face chamfer along the radial direction is located on the root circle of the engaging tooth, the end face of the wheel body that is close to the second transmission component along the axial direction can be as large as possible in the radial direction when forming a plane, and its contact area with the limiting block can be as large as possible. For example, the boundary line of its contact area along the radial direction of the shift gear can be set to the position of the root circle of the engaging tooth, thereby increasing the limiting contact area of ​​the limiting block and improving the limiting reliability.

[0044] In some embodiments, an electric drive axle is also disclosed, including any of the aforementioned gear shifting devices. The electric drive axle may include a drive motor, a reducer, a differential, and the gear shifting device described in any of the above embodiments. The gear shifting device is disposed between the drive motor and the reducer. The first transmission member 1 is connected to the output shaft of the drive motor. Two shift gears 3 correspond to the first gear and the second gear, respectively. The second transmission member 2 (meshing sleeve) is driven to move axially through a shift fork to achieve gear switching. Due to the use of a meshing sleeve structure with a limiting block wider than two second teeth, the end face of the limiting block forms a surface contact limit with the end face of the shift gear body, which can reliably withstand the axial force generated by the bevel teeth after gear engagement and prevent excessive movement of the meshing sleeve. The electric drive axle of this embodiment has the advantages of accurate shifting position, reliable limiting, strong impact resistance, and compact structure, and is especially suitable for new energy vehicles with strict requirements for axial space.

[0045] In some embodiments, a design method for any of the above-described gear shifting transmissions is disclosed, comprising: Obtain the maximum axial resultant force F transmitted by the gear shifting transmission device when it is in the first state; The thickness of the limiting block 22 along the axial direction is determined based on the axial resultant force F, ensuring that the maximum stress value of the limiting block 22 under the action of the axial resultant force F is less than one-third of the yield strength of the limiting block 22 material. This design method first calculates the axial resultant force F acting on the end face of the limiting block when the gear shifting device transmits maximum torque. Taking an electric drive axle as an example: obtain the maximum output torque Tmax of the drive motor and the total speed ratio I of the first (or second) gear. Convert Tmax to the engaging teeth of the shifting gear through I to obtain the maximum torque transmitted by the engaging teeth T = Tmax × I. Then, the circumferential force Ft = T / r at the engaging teeth can be calculated, where r is the radius of the meshing point between the engaging teeth and the second tooth. Since the second tooth and the engaging tooth use bevel meshing, this circumferential force will decompose into an axial force Fa. Subtracting the friction between the second and first transmission components from the axial force Fa yields the axial resultant force F. This axial resultant force F is then evenly distributed to the end faces of multiple limiting blocks (each limiting block bears F / n, where n is the number of limiting blocks). A model of the limiting block is established using finite element simulation software. The axial force is applied, and the maximum stress σmax at the root and end face of the limiting block is calculated. The axial thickness of the limiting block (i.e., ...) is adjusted. Figure 4 The axial dimension of the middle limiting block is determined until σmax is less than one-third of the yield strength σs of the limiting block material, i.e., σmax < σs / 3. This design method provides a quantitative design basis for the thickness of the limiting block, ensuring that the limiting block has sufficient safety margin under maximum working conditions, thereby avoiding plastic deformation or fracture of the limiting block.

[0046] In some embodiments, the second tooth 21 along the axial direction includes a straight tooth located in the middle for meshing with the first tooth 11 and bevel teeth located at both ends for meshing with the engagement tooth 32. The design method of the gear shifting transmission includes: When manufacturing the second tooth 21, a long straight tooth is first drawn out using a broach, and then the two ends of the long straight tooth are extruded using a tapered extrusion method to form tapered teeth. This embodiment provides a method for machining the second tooth. This method adopts an integral broaching process: first, a spline (i.e., a long straight tooth) with straight teeth of the entire length is drawn out on the inner wall of the meshing sleeve in one go using a broach. The axial length of the long straight tooth covers the entire length of the final second tooth (including the straight tooth portion in the middle and the tapered tooth portions at both ends). Then, a tapered extrusion process is used, using a special extrusion tool to extrude and shape the two ends of the long straight tooth, so that the tooth shape at both ends becomes tapered teeth, while the middle portion remains straight teeth. This process does not require machining a relief groove, so the tooth body on both sides of the limiting block maintains material continuity with the limiting block body, forming an integral structure, which significantly improves the structural strength and impact resistance of the limiting block; the extrusion process produces a hardened layer on the surface of the tapered teeth, improving the tooth surface hardness and wear resistance; this process has high processing efficiency and is suitable for mass production.

[0047] In some embodiments, a shifting method is disclosed, applying any of the above-described shifting transmission devices, wherein at least one shifting gear 3 includes two shifting gears 3 located on both sides of the second transmission member 2, and the shifting method includes: Shift self-learning steps: Drive the second transmission component 2 axially to one side until the limit block 22 contacts the end face of the gear body 31 of the shift gear 3 on that side, and record this position as the first limit position; then drive the second transmission component 2 axially to the other side until the limit block 22 contacts the end face of the gear body 31 of the shift gear 3 on the other side, and record this position as the second limit position, and determine the neutral position based on the first limit position and the second limit position. The shift self-learning steps are performed when the shift transmission device is first powered on or when recalibration is required. The TCU (Transmission Control Unit) controls the shift actuator (such as a motor or hydraulic system) to drive the second transmission component 2 (meshing sleeve) to slowly move to one side (e.g., the first gear side). When the limiting plane 221 of the limit block 22 contacts the end face of the gear body 31 of the shift gear 3 (first gear) on that side, the meshing sleeve cannot continue to move due to mechanical obstruction. At this time, the current or position sensor signal of the actuator will change abruptly, and the TCU records the current position as the first limit position P1. Then, the TCU drives the engagement sleeve to move in the opposite direction, towards the other side (the second gear side), until the limit block contacts the end face of the second gear, recording the second limit position P2. Finally, the neutral position (e.g., the midpoint position) is calculated based on P1 and P2. This shifting method uses the contact between the limit block and the end face of the gear as a mechanical hard limit, providing a real and reliable physical reference point for self-learning, avoiding inaccurate positioning caused by sensor drift or assembly errors. Through self-learning, the TCU can accurately determine the endpoint of the shift stroke, thereby precisely controlling the shifting action and improving the success rate and consistency of shifting.

[0048] In some embodiments, the neutral position is the midpoint between the first limit position and the second limit position. After obtaining the first limit position P1 and the second limit position P2 through self-learning, the TCU calculates the neutral position N = (P1 + P2) / 2, which is the arithmetic midpoint of the two limit positions. Setting the neutral position as the midpoint in this embodiment ensures that the clearance between the meshing sleeve and the shift gear is equal on both sides when the sleeve is in neutral. This results in symmetrical shift stroke and dynamic characteristics when shifting gears in either direction, simplifying the control algorithm and improving shift smoothness.

[0049] In some embodiments, the method further includes a gear-shifting step: a position L away from the first limiting position along the direction close to the second transmission member 2 is designated as the first target position; a position L away from the second limiting position along the direction close to the second transmission member 2 is designated as the second target position; when the second transmission member 2 moves towards the shift gear 3 at the first limiting position to shift gear, the second transmission member 2 is driven to move from neutral to the first target position and then stops; then the second transmission member 2 continues to move under the axial force of the second tooth 21 until the limiting block 22 reaches the first limiting position; when the second transmission member 2 moves towards the shift gear 3 at the second limiting position to shift gear, the second transmission member 2 is driven to move from neutral to the second target position and then stops; then the second transmission member 2 continues to move under the axial force of the second tooth 21 until the limiting block 22 reaches the second limiting position. Figure 1 As shown, after completing self-learning and determining the neutral position, normal gear shifting is performed. For first gear: the TCU sets the first target position to the distance L (i.e., P1 - L, where L is the preset anti-collision distance) of retraction from the first limit position P1 towards neutral. The TCU controls the actuator to drive the engagement sleeve to accelerate and then decelerate from the neutral position towards the first gear, precisely moving to the first target position and stopping. At this time, at the first target position, the second tooth 21 and the engagement tooth 32 have just engaged. Subsequently, the drive motor restores torque, and torque begins to be transmitted between the bevel teeth of the second tooth 21 and the bevel teeth of the engagement tooth 32, generating axial force. This axial force pushes the engagement sleeve to continue moving towards first gear until the limiting plane 221 of the limiting block 22 contacts the end face of the wheel body 31 of the first gear, reaching the first limit position, at which point gear engagement is complete. The second gear shifting process is similar. This embodiment sets an anti-collision distance L so that the actuator stops before fully contacting the hard limit when shifting gears. The axial force generated by the bevel teeth gently pushes the engagement sleeve to the limit position, avoiding the impact noise and damage caused by high-speed impact on the limit surface, while ensuring that the gear is fully engaged.

[0050] 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 preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A gear shifting and transmission device, characterized in that, include: The first transmission component includes a plurality of first teeth arranged circumferentially thereon, a first groove extending axially between two adjacent first teeth, and a clearance groove between two adjacent first teeth. At least one shift gear includes a engagement structure, the engagement structure including a wheel body and a plurality of engagement teeth evenly arranged circumferentially along the wheel body; The second transmission member, used to transmit torque in transmission cooperation with the first transmission member and the connecting structure, includes a plurality of second teeth evenly arranged circumferentially and at least one limiting block located between two adjacent second teeth. Along the circumferential direction of the second transmission member, the width of the limiting block is not less than the width shared by two adjacent second teeth. Along the radial direction of the second transmission member, the limiting block spans the root circle of the plurality of connecting teeth. Each second tooth is disposed within a first groove and slidably engages with the first groove. A limiting block is disposed within a clearance groove and slidably engages with the clearance groove. The second transmission member has a first state in which the second teeth simultaneously engage with the first teeth and the connecting teeth, and a second state in which the second teeth only engage with the first teeth and not with the connecting teeth. The second transmission member switches between the first and second states by sliding the second teeth relative to the first groove and by sliding the limiting block relative to the clearance groove.

2. The gear shifting device as described in claim 1, characterized in that, The second transmission component includes an annular meshing sleeve, the second tooth and the limiting block are located on the inner wall of the meshing sleeve, the at least one shift gear includes two shift gears located on both sides of the second transmission component, the limiting block is disposed in the middle of the inner wall of the meshing sleeve along the axial direction, the two end faces of the limiting block along the circumference of the second transmission component are continuous surfaces in the axial direction, and one of the two end faces meshes with the first tooth in the first state.

3. The gear shifting device as described in claim 2, characterized in that, The two end faces of the limiting block along the axial direction are limiting planes, and the end face of the wheel body near the meshing sleeve along the axial direction is a plane. In the second state, the limiting plane is in contact with the end face of the wheel body along the axial direction.

4. The gear shifting device as described in claim 3, characterized in that, The second transmission component includes a plurality of limiting blocks evenly arranged along its circumference.

5. The gear shifting device as described in claim 3, characterized in that, The second tooth along the axial direction includes a straight tooth located in the middle for meshing with the first tooth and bevel teeth located at both ends for meshing with the connecting tooth. The two end faces of the limiting block along the circumference of the second transmission member are surfaces for meshing with the first tooth. Along the circumference of the second transmission member, an axially extending transmission groove is formed between the limiting block and two adjacent second teeth for the insertion of the first tooth and the connecting tooth. The transmission groove is provided with a first chamfer connecting the bevel tooth and the straight tooth. The first chamfer crosses the limiting plane along the axial direction.

6. The gear shifting device as described in claim 3, characterized in that, A second chamfer is provided between the end of the limiting plane and the inner wall of the engagement sleeve, and the second chamfer is a rounded corner.

7. The gear shifting device as described in claim 2, characterized in that, The radially inner end face of the limiting block is an arc surface coaxial with the second transmission component.

8. The gear shifting device as described in any one of claims 1 to 7, characterized in that, An end face chamfer is provided at one end of the engaging tooth near the second transmission member along the axial direction. The end face chamfer is used to guide the second tooth when switching from the second state to the first state. Along the radial direction of the shift gear, the starting contour line of the end face chamfer is located on the root circle of the plurality of engaging teeth.

9. An electric drive bridge, characterized in that, Includes the gear shifting and transmission device according to any one of claims 1-8.

10. A design method for a gear shifting transmission device according to any one of claims 1 to 8, characterized in that, include: Obtain the maximum axial resultant force F transmitted by the gear shifting device when it is in the first state; The thickness of the limiting block along the axial direction is determined based on the axial resultant force F, such that the maximum stress value of the limiting block under the action of the axial resultant force F is less than one-third of the yield strength of the limiting block material.

11. The design method of the gear shifting and transmission device as described in claim 10, characterized in that, The second tooth along the axial direction includes a straight tooth located in the middle for meshing with the first tooth and bevel teeth located at both ends for meshing with the engagement tooth. The design method of the gear shifting device includes: When manufacturing the second tooth, a long straight tooth is first drawn out using a broach, and then the two ends of the long straight tooth are squeezed to form the conical tooth using a cone-shaped extrusion method.

12. A gear-shifting method, characterized in that, Using the gear shifting device according to any one of claims 1 to 8, the at least one shift gear includes two shift gears located on both sides of the second transmission member, and the gear shifting method includes: Shift self-learning steps: Drive the second transmission component to move axially to one side until the limiting block contacts the end face of the shift gear on that side, and record this position as the first limiting position; then drive the second transmission component to move axially to the other side until the limiting block contacts the end face of the shift gear on the other side, record this position as the second limiting position, and determine the neutral position based on the first limiting position and the second limiting position.

13. The gear shifting method as described in claim 12, characterized in that, The neutral position is the middle position between the first limiting position and the second limiting position.

14. The gear shifting method as described in claim 13, characterized in that, The process also includes a gear-shifting step: A position L away from the first limiting position along the direction close to the second transmission member is designated as the first target position; a position L away from the second limiting position along the direction close to the second transmission member is designated as the second target position. When the second transmission member moves towards the shift gear at the first limiting position to shift gear, the second transmission member is driven to move from the neutral position to the first target position and then stops. The second transmission member then continues to move under the axial force acting on the second tooth until the limiting block reaches the first limiting position. Similarly, when the second transmission member moves towards the shift gear at the second limiting position to shift gear, the second transmission member is driven to move from the neutral position to the second target position and then stops. The second transmission member then continues to move under the axial force acting on the second tooth until the limiting block reaches the second limiting position.

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