Patent Publication Number: US-2022221054-A1

Title: Gear shifting mechanism, gearbox, powertrain, and electric vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Chinese Patent Application No. 202110349748.2, filed on Mar. 31, 2021, which is hereby incorporated by reference in its entirety. 
     TECHNICAL FIELD 
     The present invention relates to the field of electric vehicle technologies, and in particular, to a gear shifting mechanism, a gearbox, a powertrain, and an electric vehicle. 
     BACKGROUND 
     An electric vehicle is driven by a motor. A power output by the motor is decelerated and torqued by a gearbox, and then transmitted to a wheel through an axle shaft (also referred to as a drive shaft, drive shaft) connected to the gearbox in a transmission manner, to drive the electric vehicle to travel. 
     A single-speed gearbox can search for an optimal speed ratio only within a limited vehicle speed range (for example, less than 150 km/h) to achieve a balance between costs and efficiency. However, a high efficiency area of the motor is concentrated at medium and low rotational speeds. Therefore, an operating point of the motor cannot be adjusted by using a fixed speed ratio of the single-speed gearbox. In addition, when the single-speed gearbox is used, and a higher speed is reached, the motor enters a constant power area at a high rotational speed due to characteristics of the motor, and an output torque of the motor decreases sharply. This causes power shortage of the electric vehicle at the high rotational speed. Therefore, a current two-speed gearbox is a major development trend in the electric vehicle field in the future. The two-speed gearbox is capable of changing a speed ratio to adjust an operating point of a motor, so as to increase an output torque of the motor at a high rotational speed, and also improve efficiency. 
     A gear shifting process of the two-speed gearbox may be implemented by using a gear shifting mechanism. Stability of power transmission of the gear shifting mechanism in the gear shifting process is an important factor that affects driving stability of an electric vehicle. 
     SUMMARY 
     This application provides a gear shifting mechanism, a gearbox, a powertrain, and an electric vehicle, to improve stability of power transmission of a gear shifting mechanism in a gear shifting process, so as to improve driving performance of an electric vehicle. 
     According to a first aspect, this application provides a gear shifting mechanism. The gear shifting mechanism includes a gear, a gear hub, a one-way clutch, and a sliding apparatus. The gear includes a body. A first convex wall and a second convex wall are disposed on an end face of the body. The first convex wall is disposed around a shaft hole of the body. A first toothed structure is disposed at an end, of the first convex wall, that is away from the body. The second convex wall and the first convex wall are disposed on a same side of the body. The second convex wall is disposed around the shaft hole of the body. A diameter of the second convex wall is less than that of the first convex wall. The gear hub is sleeved on the second convex wall. The one-way clutch is disposed between the gear hub and the second convex wall. An inner ring of the one-way clutch is connected to the second convex wall. An outer ring of the one-way clutch is connected to the gear hub. 
     When the sliding apparatus is specifically disposed, the sliding apparatus may be radially fixed to the gear hub, and the sliding apparatus is capable of sliding on a surface of the gear hub in a direction toward or away from the gear. In a possible implementation of this application, the sliding apparatus may include a supporting frame, a rolling component, and a sliding sleeve. The supporting frame is sleeved on the gear hub, and the supporting frame is radially fixed to the gear hub. In addition, a second toothed structure is disposed at an end, of the supporting frame, that faces the first convex wall, and the second toothed structure may be meshed with the first toothed structure of the first convex wall. The supporting frame is further disposed with a mounting slot. The rolling component is mounted in the mounting slot, and the rolling component is in contact with the surface of the gear hub. The sliding sleeve is sleeved on the supporting frame. The rolling component is confined between the sliding sleeve and the gear hub. The sliding sleeve is capable of driving the supporting frame and the rolling component to slide on the surface of the gear hub in a direction toward or away from the gear. 
     In a possible implementation of this application, when the second toothed structure is meshed with the first toothed structure, the gear and a rotary shaft rotate synchronously. In this application, the second toothed structure may be stably meshed with the first toothed structure, to avoid power loss due to disengagement of the one-way clutch resulting from power fluctuation, and ensure stable power transmission between the gear and the gear hub. In addition, when the second toothed structure is detached from the first toothed structure, in a case, the one-way clutch may still lock the second toothed structure and the first toothed structure, so that the second toothed structure and the first toothed structure can rotate synchronously. In another case, the one-way clutch may be in an open state, and the one-way clutch does not hinder relative movement between the second toothed structure and the first toothed structure, so that the second toothed structure and the first toothed structure can rotate differentially. 
     In a possible implementation of this application, the gear shifting mechanism may further include the rotary shaft, and the rotary shaft penetrates the shaft hole of the body. In addition, the gear hub may be fixedly connected to the rotary shaft. In this way, power transmission between the gear and the gear hub can be converted into power transmission between the gear and the rotary shaft, so that the gear shifting mechanism implements power transmission between the gear shifting mechanism and a wheel of an electric vehicle by using the rotary shaft. 
     A bearing may be further disposed in the shaft hole of the body of the gear, so that the gear can be sleeved on the rotary shaft by using the bearing, and the gear and the rotary shaft can rotate differentially. 
     In this application, teeth of the second toothed structure of the supporting frame and teeth of the first toothed structure of the first convex wall may be both arranged in trapezoidal structures, so that the second toothed structure can be meshed with the first toothed structure. 
     In a possible implementation of this application, a locking structure of the supporting frame may be designed, so that the second toothed structure of the supporting frame can be stably meshed with the first toothed structure of the first convex wall. During specific implementation, a first stepped surface, a second stepped surface, and an arc connection surface used to connect the first stepped surface and the second stepped surface may be disposed on a surface, of the gear hub, that is used to fit the sliding apparatus. The first stepped surface is located on a side, of the second stepped surface, that is away from the rotary shaft, so that a step is formed between the first stepped surface and the second stepped surface. In addition, a diameter of the rolling component is greater than a wall thickness of the supporting frame. In this way, when the second toothed structure is meshed with the first toothed structure, the rolling component is tangent to the second stepped surface and an inner surface of the sliding sleeve. In this case, movement of the rolling component in a direction away from the first toothed structure is blocked by the step and the sliding sleeve. In addition, because the rolling component is mounted on the supporting frame, a location of the supporting frame is locked, and the second toothed structure of the supporting frame is stably meshed with the first toothed structure of the first convex wall, thereby implementing stable power transmission of the gear shifting mechanism. 
     It can be understood that a specific manner of disposing the rolling component is not limited in this application. For example, the rolling component may be a pin roller. In this case, the mounting slot on the supporting frame may be provided as a rectangular slot, so that the rolling component can be confined in the rectangular slot. 
     In a possible implementation of this application, a should is further disposed at an end, of the supporting frame, that is away from the first convex wall, and the sliding sleeve is disposed on a side, of the should, that faces the gear. In this way, when the sliding sleeve slides in a direction away from the first convex wall, the sliding sleeve can abut against the should, to push the supporting frame to slide. 
     In addition, an arc surface is further disposed on the inner surface of the sliding sleeve. When the sliding sleeve slides in the direction away from the first convex wall, the rolling component can be tangent to the arc surface of the sliding sleeve, so that the rolling component can slide along with the supporting frame, until the second toothed structure of the supporting frame is detached from the first toothed structure of the first convex wall. In this state, the rolling component rolls from the second stepped surface to the first stepped surface, and the rolling component is tangent to the first stepped surface and the arc surface of the sliding sleeve, so that the rolling component is confined between the first stepped surface and the sliding sleeve. 
     In a possible implementation of this application, sliding of the sliding sleeve may be implemented by using a shifting fork. During specific implementation, a groove may be disposed on a surface, of the sliding sleeve, that is away from the gear hub. The shifting fork may snap into the groove, so that the shifting fork can drive the sliding sleeve to slide on the surface of the gear hub in a direction toward or away from the gear. 
     According to a second aspect, this application provides a gearbox. The gearbox may include the gear shifting mechanism in the first aspect. A gear of the gear shifting mechanism may be meshed with a gear on another rotary shaft in the gearbox, to implement power transmission between the two gears. Stability of power transmission of the gear shifting mechanism provided in this application is relatively high. Therefore, stability of power transmission of the gearbox using the gear shifting mechanism is improved. 
     According to a third aspect, this application provides a powertrain. The powertrain includes a motor and a gearbox. A power output by the motor may be transmitted to the gearbox through a gear shifting mechanism. Power transmission of the gearbox is relatively stable. Therefore, stability of power transmission between the motor and the gearbox can be improved. 
     According to a fourth aspect, this application further provides an electric vehicle. The electric vehicle includes the powertrain in the third aspect. In a gear shifting process, stability of power transmission of the electric vehicle is relatively high, so that the electric vehicle can travel smoothly. This helps improve driving experience of a user. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic diagram of a structure of a gear shifting mechanism according to an embodiment of this application; 
         FIG. 2  is a schematic diagram of a structure of a gear according to an embodiment of this application; 
         FIG. 3  is a cross-sectional view of a gear shifting mechanism according to an embodiment of this application; 
         FIG. 4  is a schematic diagram of differential rotation of a gear and a rotary shaft according to an embodiment of this application; 
         FIG. 5  is a cross-sectional view of a gear shifting mechanism according to another embodiment of this application; 
         FIG. 6  is a cross-sectional view of a gear shifting mechanism according to another embodiment of this application; 
         FIG. 7  is a schematic diagram of a structure of a gear shifting mechanism according to another embodiment of this application; 
         FIG. 8  is a cross-sectional view of a gear shifting mechanism according to another embodiment of this application; 
         FIG. 9  is a schematic diagram of a structure of fitting between a sliding apparatus and a gear hub according to an embodiment of this application; 
         FIG. 10  is a schematic diagram of a meshed state of a second toothed structure and a first toothed structure according to an embodiment of this application; 
         FIG. 11  is a schematic diagram of a structure of fitting between a sliding apparatus and a gear hub according to another embodiment of this application; and 
         FIG. 12  is a cross-sectional view of a gear shifting mechanism according to another embodiment of this application. 
     
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
       1 : gear;  101 : gear face;  102 : body;  1021 : shaft hole;  103 : first convex wall;  1031 : first toothed structure; 
       104 : second convex wall;  2 : gear hub;  201 : first stepped surface;  202 : second stepped surface;  203 : arc connection surface; 
       3 : sliding apparatus;  301 : second toothed structure;  302 : groove;  303 : supporting frame;  3031 : mounting slot; 
       3032 : should;  304 : rolling component;  305 : sliding sleeve;  3051 : arc surface;  4 : rotary shaft;  5 : bearing;  6 : one-way clutch; and  7 : shifting fork. 
     Description of Embodiments 
     To make objectives, technical solutions, and advantages of this application clearer, the following further describes this application in detail with reference to the accompanying drawings. It should be noted that in the description of this application, “at least one” means one or more, and “a plurality of” means two or more. In view of this, in the embodiments of the present invention, “a plurality of” may also be understood as “at least two”. The term “and/or” describes an association relationship between associated objects and indicates that three relationships may exist. For example, A and/or B may indicate the following three cases: Only A exists, both A and B exist, and only B exists. In addition, the character “/” generally indicates an “or” relationship between the associated objects, unless otherwise specified. In addition, it should be understood that in the description of this application, the terms such as “first” and “second” are merely used for distinguishing and description, but should not be understood as indicating or implying relative importance, or should not be understood as indicating or implying a sequence. 
     Reference to “an embodiment”, “some embodiments”, or the like described in this specification indicates that one or more embodiments of this application include a specific feature, structure, or characteristic described with reference to the embodiment. Therefore, in this specification, statements, such as “in an embodiment”, “in some embodiments”, “in some other embodiments”, and “in other embodiments”, that appear at different places do not necessarily mean reference to a same embodiment, instead, they mean “one or more but not all of the embodiments”, unless otherwise specifically emphasized. The terms “include”, “comprise”, “have”, and their variants all mean “include but are not limited to”, unless otherwise specifically emphasized. 
     In recent years, electric vehicles develop rapidly. The electric vehicles use electric power as a power source. A fuel engine is replaced with a motor. This can not only achieve zero emission, low noise, and zero pollution, but also greatly save diminishing oil energy. With increasing maturity and development of power battery technologies for the electric vehicles, the electric vehicles inevitably become a main development trend of the automobile industry in the future. 
     As a core of an electric vehicle, a powertrain may usually include apparatuses such as a power supply, a motor, a motor controller, and a gearbox. A power output by the motor is decelerated and torqued by the gearbox, and then transmitted to a wheel through a drive shaft, to drive the electric vehicle to travel. 
     Currently, an electric vehicle usually uses a two-speed gearbox, to change a speed ratio to adjust an operating point of a motor, so as to increase an output torque at a high rotational speed, and also improve efficiency. The two-speed gearbox may be usually disposed with a gear shifting mechanism to perform gear shifting, and a function of the gear shifting mechanism is implemented mainly based on a change of a transmission relationship between components. However, a gearbox usually uses a synchronizer for gear shifting. In a gear shifting process of the gearbox, interruption of power transmission of the gear shifting mechanism affects driving stability of the electric vehicle. 
     A gear shifting mechanism provided in this application is intended to resolve the foregoing problem, to avoid power interruption of the gear shifting mechanism in a gear shifting process, so as to improve stability of power transmission of the gear shifting mechanism. The gear shifting mechanism is used in a gear shifting process of a gearbox, and can effectively avoid power interruption in the gear shifting process of the gearbox, so as to improve driving stability of an electric vehicle having the gearbox. 
     First, refer to  FIG. 1 .  FIG. 1  is a schematic diagram of a structure of a gear shifting mechanism according to an embodiment of this application. The gear shifting mechanism may include a gear  1 , a gear hub  2 , and a sliding apparatus  3 . A gear face  101  of the gear  1  may be used to be meshed with another gear. For example, the gear face  101  of the gear  1  may be meshed with another gear in a gearbox, to implement power transmission between the gear shifting mechanism and the another gear. 
       FIG. 2  is a schematic diagram of a structure of the gear  1  according to an embodiment of this application. In this application, the gear  1  includes a body  102 , and the gear face  101  is disposed on an outer ring of the body  102 . A first convex wall  103  is disposed on an end face of the body  102 , and the first convex wall  103  is disposed around a shaft hole  1021  of the body  102 . In the embodiment shown in  FIG. 2 , the first convex wall  103  may be disposed in an annular structure, and a diameter of the first convex wall  103  is less than an inner diameter of the gear face  101  of the gear  1 . In addition, the first convex wall  103  may be further disposed coaxially with the body  102  of the gear  1 , so that a structure of the gear  1  is relatively compact. 
     A first toothed structure  1031  may be disposed at an end, of the first convex wall  103 , that is away from the body  102 . The first toothed structure  1031  has a plurality of teeth. The plurality of teeth may be evenly distributed in a direction around the first convex wall  103 , but this does not constitute a limitation. 
     It can be understood that, in some possible embodiments of this application, the first convex wall  103  may alternatively include a plurality of arc protrusions with the first toothed structure  1031 , to effectively reduce a weight of the gear  1 . In addition, in this embodiment, a specific manner of disposing the first convex wall  103  is similar to that of disposing the first convex wall  103  in the annular structure. Details are not described herein again. 
     Still refer to  FIG. 2 . A second convex wall  104  may be further disposed on the end face of the body  102  of the gear  1 . The second convex wall  104  may be disposed in an annular structure around the shaft hole  1021  of the gear  1 . The second convex wall  104  and the first convex wall  103  are disposed on a same side of the body  102 . The second convex wall  104  is disposed coaxially with the first convex wall  103 , and a diameter of the second convex wall  104  is less than that of the first convex wall  103 . 
     Refer to both  FIG. 1  and  FIG. 2 . The gear hub  2  described in the foregoing embodiment may be sleeved on the second convex wall  104 , the sliding apparatus  3  is sleeved on the gear hub  2 , and a second toothed structure  301  is disposed at an end of a side, of the sliding apparatus  3 , that faces the first convex wall  103 . The second toothed structure  301  may be meshed with the first toothed structure  1031 . 
     For ease of understanding a connection relationship between the gear hub  2 , the sliding apparatus  3 , and the gear  1 , refer to  FIG. 3 .  FIG. 3  is a cross-sectional view of the gear shifting mechanism according to an embodiment of this application. In this embodiment, the gear shifting mechanism may further include a rotary shaft  4 . The rotary shaft  4  penetrates the shaft hole  1021  of the body  102  of the gear  1 . In addition, a bearing  5  may be further disposed in the shaft hole  1021  of the body  102  of the gear  1 , so that the gear  1  is sleeved on the rotary shaft  4  by using the bearing  5 , and the gear  1  and the rotary shaft  4  can rotate independently at different rotational speeds. In some possible embodiments of this application, the bearing  5  may be, but is not limited to, a deep groove ball bearing, a needle roller bearing, or the like. 
     It can be learned from the embodiment shown in  FIG. 1  that, in this application, the gear hub  2  and the sliding apparatus  3  may also be disposed in annular structures. Still refer to  FIG. 3 . The gear hub  2  is sleeved on the second convex wall  104  of the gear  1 , and an end of the gear hub  2  is further inserted between the first convex wall  103  and the second convex wall  104 . 
     In addition, the gear hub  2  may be further sleeved on the rotary shaft  4 , so that the gear hub  2  and the gear  1  can be disposed coaxially. In this application, the gear hub  2  and the rotary shaft  4  may be fixedly connected. For example, the gear hub  2  and the rotary shaft  4  may be connected by using a spline, a flat key, or the like, or may be connected through soldering or in an interference fit manner, so that the gear hub  2  can rotate along with the rotary shaft  4 . 
     Still refer to  FIG. 3 . A one-way clutch  6  is further disposed between the gear hub  2  and the second convex wall  104 , and the one-way clutch  6  is sleeved on the second convex wall  104 . In this application, a specific form of disposing the one-way clutch  6  is not limited. For example, the one-way clutch  6  may be a roller one-way clutch or a wedge one-way clutch. 
     In a possible embodiment of this application, the one-way clutch  6  may include an inner ring, an outer ring, and a locking structure disposed between the inner ring and the outer ring. The locking structure may be configured to lock relative rotation between the outer ring and the inner ring in a specific direction, so that the outer ring and the inner ring rotate synchronously; and skip locking relative rotation in another direction, so that the outer ring and the inner ring rotate relative to each other. 
     Still refer to  FIG. 3 . In this application, the inner ring of the one-way clutch  6  may be connected to the second convex wall  104 , and the outer ring may be connected to the gear hub  2 . In this way, when the rotary shaft  4  tends to rotate relative to the gear  1  in a first direction, the one-way clutch  6  may lock relative movement between the gear hub  2  and the second convex wall  104 , to hinder relative movement between the gear hub  2  and the second convex wall  104 , so that the rotary shaft  4  and the gear  1  rotate synchronously. When the rotary shaft  4  rotates relative to the gear  1  in the first direction or a second direction, where the second direction is opposite to the first direction, the one-way clutch  6  does not hinder relative movement between the gear hub  2  and the second convex wall  104 . In this case, the rotary shaft  4  and the gear  1  can rotate at different rotational speeds, thereby implementing differential rotation of the rotary shaft  4  and the gear  1 . 
     It can be learned from the descriptions of the foregoing embodiment that the sliding apparatus  3  may be sleeved on the gear hub  2 . In addition, the sliding apparatus  3  may further slide on a surface of the gear hub  2  along a side that faces or is away from the gear  1 , so that the second toothed structure  301  of the sliding apparatus  3  can be meshed with the first toothed structure  1031  of the first convex wall  103 , or the second toothed structure  301  and the first toothed structure  1031  that are meshed are detached from each other. 
     To implement sliding of the sliding apparatus  3  on the surface of the gear hub  2 , in a possible embodiment of this application, the gear shifting mechanism may further include a shifting fork  7 . A groove  302  may be disposed on a surface, of the sliding apparatus  3 , that is away from the gear hub  2 . The shifting fork  7  may snap into the groove  302 , to implement connection between the shifting fork  7  and the sliding apparatus  3 . In addition, the shifting fork  7  may be further connected to a gear shifting controller. In this way, with the gear shifting controller, the shifting fork can drive the sliding apparatus  3  to slide on the surface of the gear hub  2 , to control a meshed or detached state of the second toothed structure  301  of the sliding apparatus  3  and the first toothed structure  1031  of the first convex wall  103  of the gear  1 . 
     It can be understood that the foregoing embodiment provides only one possible connection manner of the shifting fork  7  and the sliding apparatus  3 . In some other embodiments of this application, the shifting fork  7  and the sliding apparatus  3  are connected in another possible manner. In addition, the sliding of the sliding apparatus  3  on the surface of the gear hub  2  may be alternatively implemented by disposing another possible axial sliding system. 
     After the structure of the gear shifting mechanism provided in the foregoing embodiment of this application is understood, the following describes in detail an operating status and a gear shifting process of the gear shifting mechanism with reference to the accompanying drawings. 
     First, refer to  FIG. 3 . In an embodiment shown in  FIG. 3 , the second toothed structure  301  of the sliding apparatus  3  and the first toothed structure  1031  of the first convex wall  103  of the gear  1  are in a detached state. 
       FIG. 4  shows differential rotation of the gear  1  and the rotary shaft  4  in a view along a direction A in  FIG. 3 . A direction of the differential rotation of the gear  1  and the rotary shaft  4  may be a clockwise direction or a counterclockwise direction. In an embodiment shown in  FIG. 4 , the differential rotation of the gear  1  and the rotary shaft  4  is described by using an example in which both the gear  1  and the rotary shaft  4  rotate clockwise. A rotational speed of the gear  1  may be denoted as ω1, and a rotational speed of the rotary shaft  4  may be denoted as ω2. Because the gear hub  2  is fixedly connected to the rotary shaft  4 , the gear hub  2  may rotate synchronously with the rotary shaft  4 . In this case, a rotational speed of the gear hub  2  is also ω2. In this embodiment of this application, the rotational speed ω1 of the gear  1  may be greater than the rotational speed ω2 of the rotary shaft  4 . In this state, the one-way clutch  6  does not lock relative rotation between the second convex wall  104  and the gear hub  2 , and therefore does not lock relative rotation between the gear  1  and the rotary shaft  4 , to implement the differential rotation of the gear  1  and the rotary shaft  4 . In this case, the gear  1  and the rotary shaft  4  can rotate independently. In this application, a differential rotation state of the gear  1  and the rotary shaft  4  may be denoted as a first-speed operating state of the gear shifting mechanism. 
     It can be understood that, in this embodiment of this application, the sliding apparatus  3  may be alternatively connected to the gear hub  2  by using a spline or the like, so that the sliding apparatus  3  can not only slide on the surface of the gear hub  2  in a direction toward or away from the gear  1 , but also rotate synchronously with the gear hub  2 . 
     In the foregoing embodiment, the differential rotation of the gear  1  and the rotary shaft  4  is described by using the rotation of the gear  1  and the rotary shaft  4  in the clockwise direction. In some other embodiments of this application, the differential rotation of the gear  1  and the rotary shaft  4  may be alternatively implemented when the gear  1  and the rotary shaft  4  rotate counterclockwise. For example, the gear  1  and the rotary shaft  4  may rotate counterclockwise, and the rotational speed ω1 of the gear  1  is less than the rotational speed ω2 of the rotary shaft  4 . 
     In a gear shifting process of the gear shifting mechanism, a relative rotation relationship between the gear  1  and the rotary shaft  4  may change. In this application, the mechanism may implement gear shifting through a change of a location of the sliding apparatus  3 . During specific implementation, the sliding apparatus  3  may slide from a location shown in  FIG. 3  in a direction toward the gear  1 , until the sliding apparatus  3  slides to a location shown in  FIG. 5 .  FIG. 5  is a cross-sectional view showing that the second toothed structure  301  of the sliding apparatus  3  of the gear shifting mechanism and the first toothed structure  1031  of the first convex wall  103  of the gear  1  are in a meshed state according to an embodiment of this application. 
     In the embodiment shown in  FIG. 5 , the second toothed structure  301  of the sliding apparatus  3  and the first toothed structure  1031  of the first convex wall  103  of the gear  1  are in the meshed state, and the gear  1  and the rotary shaft  4  rotate in a direction that is the same as or opposite to a direction shown in  FIG. 4 . In this application, a synchronous rotation state of the gear  1  and the rotary shaft  4  may be denoted as a second-speed operating state of the gear shifting mechanism. 
     It can be understood that, with the gear shifting mechanism provided in this application, the one-way clutch  6  is disposed between the gear hub  2  and the second convex wall  104 , and with respect to the gear hub  2 , the second convex wall  104  is located on a side, of the one-way clutch  6 , that is close to the rotary shaft  4 . In this way, in a gear shifting process of the gear shifting mechanism, an acting force of the one-way clutch  6  is applied to the second convex wall  104  and the gear hub  2 , to reduce impact of a change of an operating status of the one-way clutch  6  on stability of meshing between the gear  1  and another gear. 
     In addition, the second toothed structure  301  of the sliding apparatus  3  is stably meshed with the first toothed structure  1031  of the first convex wall  103 , so that stability of power transmission can be maintained. This avoids interruption of power transmission between the gear  1  and the rotary shaft  4 , thereby improving driving stability of an electric vehicle to which the gear shifting mechanism is applied. 
     When the one-way clutch  6  locks relative rotation between the gear  1  and the rotary shaft  4 , the operating status of the one-way clutch  6  is likely to switch due to impact of power fluctuation (for example, in a vehicle bumping scenario). It can be learned from the descriptions of the foregoing embodiment that switching of the operating status of the one-way clutch  6  affects stability of power transmission of the gear shifting mechanism. Stability of the operating status of the one-way clutch  6  can be maintained through reliability of the meshing between the first toothed structure  1031  and the second toothed structure  301 . In view of this, in some embodiments of this application, stable meshing between the first toothed structure  1031  and the second toothed structure  301  is implemented by designing a location locking structure of the sliding apparatus  3 . 
     During specific implementation, refer to  FIG. 6 .  FIG. 6  is a cross-sectional view of a gear shifting mechanism according to another embodiment of this application. The gear shifting mechanism shown in  FIG. 6  differs from that in the foregoing embodiment mainly in a manner of disposing the sliding apparatus  3 . In this embodiment, the sliding apparatus  3  may include a supporting frame  303 , a rolling component  304 , and a sliding sleeve  305 . The supporting frame  303  may have an annular structure. The supporting frame  303  is sleeved on the gear hub  2 , and the supporting frame  303  may be radially fixed to the gear hub  2 , so that the supporting frame  303  and the gear hub  2  can rotate synchronously. In addition, a second toothed structure  301  is disposed at an end of a side, of the supporting frame  303 , that faces the first convex wall  103 , and the second toothed structure  301  may be meshed with the first toothed structure  1031 . In the embodiment shown in  FIG. 6 , the second toothed structure  301  and the first toothed structure  1031  are in a meshed state. 
       FIG. 7  shows a fitting relationship between the supporting frame  303 , the gear hub  2 , and the gear  1 . The supporting frame  303  may be connected to the gear hub  2  by using a spline, but this does not constitute a limitation, so that the supporting frame  303  can not only slide on the surface of the gear hub  2  in a direction toward or away from the gear  1 , but also rotate along with the gear hub  2 . In addition, the supporting frame  303  is disposed with a mounting slot  3031 . The rolling component  304  is mounted in the mounting slot  3031 , the rolling component  304  is in contact with the surface of the gear hub  2 , and the rolling component  304  is capable of rolling in the mounting slot  3031 . In a possible embodiment of this application, the rolling component  304  may be a pin roller, and the mounting slot  3031  may be provided as a rectangular slot, so that the rolling component  304  can be confined in the mounting slot  3031 . In this embodiment, the rolling component  304  is disposed as a pin roller, so that a contact area between the rolling component  304  and the gear hub  2  can be effectively increased, to improve stability for supporting the rolling component  304  by the gear hub  2 . In some other possible embodiments of this application, the rolling component  304  may be alternatively disposed as a ball. 
     The sliding sleeve  305  may be configured to drive the supporting frame  303  and the rolling component  304  to slide on the surface of the gear hub  2  in a direction toward or away from the first toothed structure  1031 . For ease of describing a fitting relationship between the sliding sleeve  305 , the supporting frame  303 , and the rolling component  304 , refer to  FIG. 8 .  FIG. 8  is a schematic diagram of the fitting relationship between the sliding sleeve  305 , the supporting frame  303 , and the rolling component  304  in the gear shifting mechanism in the embodiment shown in  FIG. 6 . It can be learned from  FIG. 8  that the sliding sleeve  305  may be sleeved on the supporting frame  303 , and the rolling component  304  may be confined between the sliding sleeve  305  and the gear hub  2 . In addition, a groove  302  may be disposed on a surface, of the sliding sleeve  305 , that is away from the gear hub  2 , and a shifting fork  7  may snap into the groove  302 , to implement connection between the shifting fork  7  and the sliding sleeve  305 . In this way, the sliding sleeve  305  is driven, through an operation on the shifting fork  7 , to slide, and a meshed or detached state of the second toothed structure  301  of the supporting frame  303  and the first toothed structure  1031  of the first convex wall  103  of the gear  1  is controlled. 
     To enable the sliding sleeve  305  to drive the supporting frame  303  to slide in a direction away from the first toothed structure  1031 , a should  3032  may be disposed at an end, of the supporting frame  303 , that is away from the first convex wall  103 . The should  3032  is disposed on a surface of a side, of the supporting frame  303 , that is away from the gear hub  2 . Refer to both  FIG. 6  and  FIG. 8 . The sliding sleeve  305  is disposed on a side, of the should  3032 , that faces the gear  1 , and the sliding sleeve  305  may abut against the should  3032 , to effectively prevent the sliding sleeve  305  from being detached from the supporting frame  303 . 
       FIG. 9  is a schematic diagram of a structure of fitting between the sliding apparatus  3  and the gear hub  2  according to an embodiment of this application. A surface, of the gear hub  2 , that is used to fit the sliding apparatus  3  may be alternatively provided as a stepped surface. In this embodiment of this application, a stepped surface, of the gear hub  2 , that has a larger outer diameter may be referred to as a first stepped surface  201 , and a stepped surface with a smaller outer diameter is referred to as a second stepped surface  202 . In this case, the first stepped surface  201  is located on a side, of the second stepped surface  202 , that is away from the rotary shaft. In addition, the first stepped surface  201  and the second stepped surface  202  may be connected by using an arc connection surface  203 . 
     A location of the sliding apparatus  3  shown in  FIG. 9  is the same as that of the sliding apparatus  3  shown in  FIG. 6 . Therefore, it can be understood that, in the embodiment shown in  FIG. 9 , the second toothed structure  301  of the supporting frame  303  and the first toothed structure  1031  of the first convex wall  103  are in a meshed state. In this state, the rolling component  304  is separately tangent to the second stepped surface  202  of the gear hub  2  and an inner surface of the sliding sleeve  305 . It can be understood that, in this embodiment, a diameter of the rolling component  304  is greater than a wall thickness of the supporting frame  303 . In this case, if a connection between the first toothed structure  1031  of the first convex wall  103  and the second toothed structure  301  of the supporting frame  303  appears to be loose, the rolling component  304  may move back, within a small range, to the arc connection surface  203  between the first stepped surface  201  and the second stepped surface  202  of the gear hub  2 . However, because the rolling component  304  is tangent to the inner surface of the sliding sleeve  305  in this case, the rolling component  304  is confined by the sliding sleeve  305  and the second stepped surface  202  of the gear hub  2 , and no longer moves in a direction toward the first stepped surface  201 . In this way, the first convex wall  103  and the supporting frame  303  can be locked in a connected state shown in  FIG. 10 . 
       FIG. 10  is a schematic diagram of a structure when the second toothed structure  301  of the supporting frame  303  and the first toothed structure  1031  of the first convex wall  103  are in a meshed state. In some embodiments of this application, teeth of the first toothed structure  1031  and teeth of the second toothed structure  301  may be both arranged in trapezoidal structures, but this does not constitute a limitation. A cross-sectional area at the top of the trapezoidal structure is less than that at the root. The root of the trapezoidal structure is an end, of the trapezoidal structure, that is used to connect to a corresponding first convex wall or sliding sleeve. In this case, the top of the trapezoidal structure is an end, of the trapezoidal structure, that is away from the corresponding first convex wall or sliding sleeve. The teeth of the first toothed structure  1031  and the teeth of the second toothed structure  301  are arranged in the trapezoidal structures, so that the first toothed structure  1031  can be conveniently meshed with the second toothed structure  301 . 
     In addition, it can be learned from the descriptions of the foregoing embodiment that, when the second toothed structure  301  of the supporting frame  303  and the first toothed structure  1031  of the first convex wall  103  are in the meshed state, the gear shifting mechanism is in the second-speed operating state. In this case, the gear  1  and the rotary shaft  4  shown in  FIG. 6  can rotate synchronously. In addition, because relative locations of the first convex wall  103  and the supporting frame  303  can be locked in the meshed state, the gear  1  and the rotary shaft  4  can be prevented from being detached from each other in a power transmission process, so that stability of power transmission between the gear  1  and the rotary shaft  4  can be improved. 
     Still refer to  FIG. 9 . In this application, an arc surface  3051  may be further disposed on the inner surface of the sliding sleeve  305 . In a process in which the sliding sleeve  305  slides from a location shown in  FIG. 9  in a direction away from the first convex wall  103  (not shown in  FIG. 9 , where reference may be made to  FIG. 6 ), the sliding sleeve  305  abuts against the should  3032  of the supporting frame  303 , and the rolling component  304  can be tangent to the arc surface  3051  of the sliding sleeve  305 . Therefore, the sliding sleeve  305  can drive the rolling component  304  to move from the second stepped surface  202  of the gear hub  2  in a direction from the arc connection surface  203  to the first stepped surface  201 . 
       FIG. 11  is a schematic diagram of a structure when the rolling component  304  is tangent to both the first stepped surface  201  of the gear hub  2  and the arc surface  3051  of the sliding sleeve  305 . In this case, to enable the sliding sleeve  305  to continue sliding in the direction away from the first convex wall  103 , the second toothed structure  301  of the supporting frame  303  and the first toothed structure  1031  of the first convex wall  103  may be in a detached state shown in  FIG. 12 . It can be learned from the descriptions of the foregoing embodiment that, when the second toothed structure  301  of the supporting frame  303  and the first toothed structure  1031  of the first convex wall  103  are in the detached state, the gear shifting mechanism is in the first-speed operating state. In this case, the gear  1  and the rotary shaft  6  can rotate independently, to implement differential rotation of the gear  1  and the rotary shaft  6 . 
     In the foregoing embodiment, the gear shifting process of switching the gear shifting mechanism from the second-speed operating state to the first-speed operating state is described. On this basis, when the gear shifting mechanism needs to be switched from the first-speed operating state shown in  FIG. 12  to the second-speed operating state shown in  FIG. 6 , the sliding sleeve  305  may be enabled to slide in a direction toward the first convex wall  103 , so that the second toothed structure  301  of the supporting frame  303  is meshed with the first toothed structure  1031  of the first convex wall  103 . In this case, refer to  FIG. 6 . The rolling component  304  moves to the second stepped surface  202  of the gear hub  2 , and is tangent to both the second stepped surface  202  and the inner surface of the sliding sleeve  305 , so that the sliding apparatus  3  is locked at the location, to implement stable meshing between the second toothed structure  301  of the supporting frame  303  and the first toothed structure  1031  of the first convex wall  103 . 
     With the gear shifting mechanism provided in this embodiment of this application, the sliding apparatus  3  is disposed as a structure in which the sliding sleeve  305 , the supporting frame  303 , and the rolling component  304  cooperate with each other, and the stepped surfaces are disposed on the surface of the gear hub  2 . Therefore, when the second toothed structure  301  of the supporting frame  303  is meshed with the first toothed structure  1031  of the first convex wall  103 , the rolling component  304  can be confined by the sliding sleeve  305  and the gear hub  2 , to lock a location of the supporting frame  303 , and implement reliable meshing between the second toothed structure  301  and the first toothed structure  1031 . Therefore, the gear  1  and the rotary shaft  4  can be prevented from being detached from each other in a power transmission process, to avoid interruption of power transmission between the gear  1  and the rotary shaft  4 , thereby improving driving stability of an electric vehicle to which the gear shifting mechanism is applied. 
     In addition, with the gear shifting mechanism, because the one-way clutch  6  is disposed between the gear hub  2  and the second convex wall  104 , stability of meshing between the gear  1  and another gear can be maintained. 
     It can be understood that, in addition to the two-speed gear shifting scenario, the gear shifting mechanism provided in the foregoing embodiment of this application may be further applied to a scenario with a gear shifting requirement for more than two speeds. During specific implementation, a plurality of gear shifting mechanisms provided in this application may be disposed, and gear faces of gears of the gear shifting mechanisms may have different quantities of teeth. In this way, a transmission ratio may be changed through meshing between gear faces of gears with different quantities of teeth, to meet a multi-speed adjustment requirement. 
     In addition, when the gear shifting mechanism provided in this application is applied to a gearbox, efficiency of a powertrain using the gearbox can be improved, thereby extending a driving mileage. In this way, when a total driving mileage of an electric vehicle remains unchanged, battery usage can be reduced, to reduce costs. This has great economic value. 
     The foregoing descriptions are merely specific implementations of the present invention, but are not intended to limit the protection scope of the present invention. Any variation or replacement readily figured out by a person skilled in the art within the technical scope disclosed in the present invention shall fall within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.