Sealing structure and electric tool

Abstract

The invention relates to a sealing structure and an electric tool. Comprising a gear box which is provided with a sealed accommodating cavity for accommodating a gear; the gear box comprises a first end wall at one end of the accommodating cavity; one end of the motor shaft penetrates through the first end wall to enter the containing cavity, and a first through hole matched with the motor shaft is formed in the first end wall; the motor shaft comprises a first threaded section and a second threaded section which are sequentially arranged, the first threaded section and the second threaded section are both located in the first through hole in the axial direction of the motor shaft, and the first threaded section is closer to the containing cavity than the second threaded section; the first threaded section and the second threaded section are different in rotation direction, and the thread pitch of the second threaded section is smaller than that of the first threaded section. The radial gap between the second threaded section and the first through hole is smaller than that between the first threaded section and the first through hole. According to the technical scheme, the sealing performance is good.

Description

Technical Field

[0001] This application relates to the field of power tool technology, and in particular to a sealing structure and a power tool. Background Technology

[0002] Power tools come in a variety of types and are widely used in various fields of industrial manufacturing. Power tools generally offer multiple speeds to accommodate workpieces of different materials and sizes. Therefore, power tools are equipped with a gearbox to adjust the speed, and this gearbox contains multiple sets of transmission gears.

[0003] To reduce wear on the transmission gears, the gearbox contains lubricating oil. During operation of power tools, due to the high-speed rotation of the motor shaft, the lubricating oil in the gearbox leaks outwards from the junction between the gearbox sidewall and the motor shaft. In existing technology, seals such as rubber rings or felt rings are used on the motor shaft for sealing. However, due to the high-speed rotation of the motor shaft, these seals are prone to wear and failure. Summary of the Invention

[0004] In view of this, this application provides a sealing structure and a power tool to solve at least one problem existing in the prior art.

[0005] To achieve the above objectives, the technical solution of this application is implemented as follows:

[0006] In a first aspect, embodiments of this application provide a sealing structure, including:

[0007] A gearbox having a sealed accommodating cavity for accommodating a gear; the gearbox includes a first end wall at one end of the accommodating cavity;

[0008] One end of the motor shaft passes through the first end wall and enters the receiving cavity. The first end wall has a first through hole that mates with the motor shaft.

[0009] The motor shaft includes a first threaded segment and a second threaded segment arranged in sequence. Both the first threaded segment and the second threaded segment are located within the first through hole in the axial direction of the motor shaft. The first threaded segment is closer to the accommodating cavity than the second threaded segment. The first threaded segment and the second threaded segment have different directions of rotation, and the pitch of the second threaded segment is smaller than the pitch of the first threaded segment. The radial clearance between the second threaded segment and the first through hole is smaller than the radial clearance between the first threaded segment and the first through hole.

[0010] Optionally, the thread of the first threaded segment is a right-hand thread, and the thread of the second threaded segment is a left-hand thread.

[0011] Optionally, the radial clearance between the second threaded segment and the first through hole is greater than 0 mm and less than 0.3 mm.

[0012] Optionally, the first through hole is a stepped hole, including a first diameter segment and a second diameter segment corresponding to the first thread segment and the second thread segment, respectively; the outer diameter of the first thread segment and the outer diameter of the second thread segment are the same, and the inner diameter of the second diameter segment is smaller than the inner diameter of the first diameter segment.

[0013] Optionally, the first through hole is a cylindrical hole, and the outer diameter of the first threaded section is smaller than the outer diameter of the second threaded section.

[0014] Optionally, the motor shaft includes a shaft body and an oil sealing ring, the oil sealing ring being interference-fitted onto the outer circle of the shaft body located within the first through hole; the oil sealing ring has two external threads with different directions of rotation to form the first thread segment and the second thread segment.

[0015] Optionally, the gearbox includes an intermediate cover located at one end of the gearbox near the motor to cover the gearbox; the intermediate cover forms the first end wall.

[0016] Optionally, the sealing structure further includes a first bearing, which is sleeved on the bearing section of the motor shaft; the bearing section is located outside the end of the second threaded section away from the first threaded section and is axially connected to the second threaded section, and the first bearing is interference-fitted with the bearing section.

[0017] Secondly, this embodiment provides a sealing structure, including:

[0018] A gearbox having a sealed accommodating cavity for accommodating a gear; the gearbox further includes a first end wall at one end of the accommodating cavity;

[0019] One end of the motor shaft passes through the first end wall and enters the receiving cavity. The first end wall has a first through hole that mates with the motor shaft.

[0020] The motor shaft includes a first threaded segment and a second threaded segment arranged in sequence. Both the first threaded segment and the second threaded segment are located in the first through hole in the axial direction of the motor shaft. The first threaded segment is closer to the accommodating cavity than the second threaded segment. The first threaded segment and the second threaded segment have different directions of rotation. The thread angle of the thread in the first threaded segment is greater than or equal to 60 degrees, and the thread angle of the thread in the second threaded segment is less than or equal to 55 degrees.

[0021] Optionally, the thread of the first threaded segment is a right-hand thread, and the thread of the second threaded segment is a left-hand thread.

[0022] Optionally, the radial clearance between the second threaded segment and the first through hole is greater than 0 mm and less than 0.3 mm.

[0023] Optionally, the first through hole is a stepped hole, including a first diameter segment and a second diameter segment corresponding to the first thread segment and the second thread segment, respectively; the outer diameter of the first thread segment and the outer diameter of the second thread segment are the same, and the inner diameter of the second diameter segment is smaller than the inner diameter of the first diameter segment.

[0024] Optionally, the motor shaft includes a shaft body and an oil sealing ring, the oil sealing ring being interference-fitted onto the outer circle of the shaft body located within the first through hole; the oil sealing ring has two external threads with different directions of rotation to form the first thread segment and the second thread segment.

[0025] Thirdly, this embodiment provides a power tool that includes any of the sealing structures described above.

[0026] The sealing structure and power tool provided in this application include: a gearbox having a sealed accommodating cavity for housing a gear; the gearbox includes a first end wall at one end of the accommodating cavity; a motor shaft, one end of which passes through the first end wall and enters the accommodating cavity, the first end wall having a first through hole that mates with the motor shaft; the motor shaft includes a first threaded segment and a second threaded segment arranged sequentially, the first threaded segment and the second threaded segment both located within the first through hole in the axial direction of the motor shaft, the first threaded segment being closer to the accommodating cavity than the second threaded segment; the first threaded segment and the second threaded segment having different directions of rotation, and the pitch of the second threaded segment being less than the pitch of the first threaded segment; the radial clearance between the second threaded segment and the first through hole being less than the radial clearance between the first threaded segment and the first through hole. Therefore, the sealing structure and power tool of this application embodiment have an axially connected first threaded segment and a second threaded segment on the motor shaft, the first threaded segment and the second threaded segment having different directions of rotation, the pitch of the second threaded segment being less than the pitch of the first threaded segment, and the radial clearance between the second threaded segment and the first through hole being less than the radial clearance between the first threaded segment and the first through hole. In this way, the leaked oil will move axially along the direction of the thread. Since the two thread sections have different directions of rotation, there is an axial thrust that blocks the oil from flowing out, regardless of whether the rotation is clockwise or counterclockwise. Furthermore, the pitch of the second thread section at the outer end is smaller, resulting in a smaller clearance with the hole and a greater axial thrust on the oil, preventing the oil from flowing out along the first and second thread sections, thus providing excellent sealing performance. Therefore, the sealing structure and power tool of this application embodiment have excellent sealing performance.

[0027] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0028] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0029] Figure 1 A schematic diagram of a power tool provided in an embodiment of this application;

[0030] Figure 2 for Figure 1 A cross-sectional schematic diagram;

[0031] Figure 3 This is a schematic diagram of the assembly of the motor and gearbox in a power tool provided in an embodiment of this application;

[0032] Figure 4 This is a schematic diagram of the sealing structure provided in an embodiment of this application;

[0033] Figure 5 for Figure 4 A magnified view of a portion of point A in the middle;

[0034] Figure 6 for Figure 4 Explosion diagram (disassembled diagram).

[0035] Explanation of reference numerals in the attached figures:

[0036] 10. Gearbox; 11. First through hole; 111. First diameter section; 112. Second diameter section; 12. Intermediate cover; 20. Motor shaft; 21. First threaded section; 22. Second threaded section; 30. Oil sealing ring; 40. First bearing; 41. Shaft retaining ring. Detailed Implementation

[0037] To make the technical solution and beneficial effects of this application more apparent and understandable, a detailed description is provided below by listing specific embodiments. The accompanying drawings are not necessarily drawn to scale, and local features may be enlarged or reduced to more clearly show the details of the local features; unless otherwise defined, the technical and scientific terms used herein have the same meanings as those in the technical field to which this application pertains.

[0038] In the description of this application, the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "height", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used for the purpose of simplifying the description of this application and do not indicate that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. In other words, they should not be construed as limitations on this application.

[0039] In this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating the relative importance of the indicated features or the number of indicated technical features. Therefore, a feature specified as "first" or "second" may explicitly include at least one of those features. In the description of this application, "multiple" means at least two, such as two, three, etc.; "several" means at least one, such as one, two, three, etc., unless otherwise explicitly specified.

[0040] In this application, unless otherwise expressly defined, the terms "installation," "connection," "linking," "fixing," "setting," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can also refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0041] In this application, unless otherwise expressly defined, the terms "above," "on top of," "over," "above," "below," "below," "below," or "below" for "first feature over second feature" can refer to the first and second features being in direct contact, or to the first and second features being in indirect contact through an intermediate medium. Furthermore, "above," "over," and "below" for "first feature over second feature" can mean the first feature is directly above or diagonally above the second feature, or simply indicates that the horizontal height of the first feature is higher than the horizontal height of the second feature. Similarly, "below," "below," and "below" for "first feature over second feature" can mean the first feature is directly below or diagonally below the second feature, or simply indicates that the horizontal height of the first feature is lower than the horizontal height of the second feature.

[0042] To fully understand this application, detailed steps and structures will be presented in the following description to illustrate the technical solution of this application. Preferred embodiments of this application are described in detail below; however, in addition to these detailed descriptions, this application may have other implementation methods.

[0043] Example 1

[0044] To address the technical problems in related technologies, embodiments of this application provide a sealing structure. (See reference...) Figure 3 and Figure 4 The sealing structure includes:

[0045] Gearbox 10 has a sealed accommodating cavity for accommodating gears; gearbox 10 includes a first end wall at one end of the accommodating cavity;

[0046] The motor shaft 20 has one end passing through the first end wall and entering the receiving cavity. The first end wall has a first through hole 11 that mates with the motor shaft 20.

[0047] The motor shaft 20 includes a first threaded section 21 and a second threaded section 22 that are axially connected. Both the first threaded section 21 and the second threaded section 22 are located within the first through hole 11 in the axial direction of the motor shaft 20. The first threaded section 21 is closer to the receiving cavity than the second threaded section 22. The first threaded section 21 and the second threaded section 22 have different directions of rotation, and the pitch of the second threaded section 22 is smaller than the pitch of the first threaded section 21. The radial clearance between the second threaded section 22 and the first through hole 11 is smaller than the radial clearance between the first threaded section 21 and the first through hole 11.

[0048] The sealing structure in this application embodiment can be disposed in a magnetic drill, see [link]. Figure 1 and Figure 2 This is understandable and can also be implemented in other power tools with a gearbox 10. The following explanation will primarily focus on the sealing structure in a magnetic drill as an example to facilitate understanding.

[0049] Understandably, the gearbox 10 may include two end walls in the same direction as the motor shaft 20, and the circumferential gearbox walls may be side walls. In addition, there are top walls and bottom walls, which together form the gearbox 10. Specifically, the gearbox 10 may be rectangular or generally rectangular in shape.

[0050] The first end wall is the end wall closest to the motor, that is, the end wall through which the motor shaft 20 passes. Since the motor shaft 20 needs to rotate at high speed, the first through hole 11 cannot be sealed using rigid "plugging" methods such as interference fits or welding. Existing flexible "plugging" methods, such as rubber rings or felt rings, also suffer from wear problems.

[0051] The inventors of this invention have creatively proposed a method for sealing by using the direction of the thread to drive the lubricant to move axially in a specified direction. Furthermore, in cases where the motor shaft 20 may rotate in both directions, the inventors have creatively proposed setting two threads with different directions of rotation, with the outer thread having a smaller pitch and a smaller clearance with the hole, resulting in a greater axial thrust on the oil. Whether rotating in the forward or reverse direction, the lubricant cannot flow out along the motor shaft 20.

[0052] For example, see Figure 4 and Figure 5 The threaded section at the outer end is on the right side of the diagram. The threaded section on the right is a left-hand thread with a smaller pitch and a smaller gap with the hole, while the threaded section on the left is a right-hand thread. During the operation of the entire machine, due to the high temperature and pressure inside the gearbox 10, the lubricating oil will have the potential energy to flow out of the gearbox 10, which is the tendency to flow from left to right as shown in the diagram.

[0053] Specifically, when the motor shaft 20 rotates counterclockwise, the right-hand thread pushes the lubricating oil to the left, preventing it from flowing to the right, i.e., preventing it from flowing out of the gearbox 10, or preventing it from flowing out further. When the motor rotates clockwise, the right-hand thread pushes the lubricating oil to the right to the left-hand thread. At this time, the left-hand thread pushes the lubricating oil to the left again. Because the left-hand thread has a smaller pitch, it has more threads for the same length, and the gap between the left-hand thread and the first through hole 11 is smaller than that between the right-hand thread and the first through hole 11, the negative pressure is greater. Therefore, the axial thrust of the left-hand thread is greater, preventing the lubricating oil from continuing to flow to the right and causing it to accumulate at the right-hand thread. When the motor rotates from counterclockwise back to clockwise, the lubricating oil accumulated at the right-hand thread will be pushed back into the gearbox 10.

[0054] Furthermore, the process of pushing the lubricating oil accumulated at the right-hand thread back into the gearbox 10 is repeated, which not only plays a sealing role, but also continuously cools and lubricates the gears inside the gearbox 10, achieving two goals at once.

[0055] Specifically, lubricant can be a semi-fluid grease with a certain degree of viscosity.

[0056] The sealing structure of this embodiment features a first threaded section 21 and a second threaded section 22 axially connected on the motor shaft 20. The first threaded section 21 and the second threaded section 22 have different rotation directions, and the pitch of the second threaded section 22 is smaller than the pitch of the first threaded section 21. Furthermore, the radial clearance between the second threaded section 22 and the first through hole 11 is smaller than the radial clearance between the first threaded section 21 and the first through hole 11. This allows leaked oil to move axially along the rotation direction of the threads. Because the two threads have different rotation directions, there is an axial thrust that prevents oil from flowing out, regardless of whether the rotation is clockwise or counterclockwise. The smaller pitch of the second threaded section 22 at the outer end results in a smaller clearance with the hole, generating a greater axial thrust on the oil, preventing it from flowing out along the first threaded section 21 and the second threaded section 22, thus providing excellent sealing.

[0057] In some other embodiments of this application, the thread of the first threaded segment 21 is a right-hand thread, and the thread of the second threaded segment 22 is a left-hand thread.

[0058] Because power tools are used more frequently and / or for longer periods of time in forward rotation, i.e. Figure 3 and Figure 4 The counter-clockwise rotation in the gearbox allows for a better seal by setting the thread of the first threaded section 21 to a right-hand thread. Understandably, the end of the motor shaft 20 that enters the gearbox 10 is the power input end, and the power output end is the opposite end. Regarding the power output end... Figure 3 and Figure 4 The counterclockwise rotation in the output is the forward rotation.

[0059] In some other embodiments of this application, the radial clearance between the second threaded segment 22 and the first through hole 11 is greater than 0 mm and less than 0.3 mm.

[0060] That is, the radial clearance between the threaded section at the outer end and the first through hole 11 is very small. This allows for a greater axial thrust on the oil. Here, the radial clearance between the threaded section and the first through hole 11 refers to the clearance between the major diameter of the thread and the hole wall.

[0061] In other embodiments of this application, reference continues to be made to... Figure 4 and Figure 5 The first through hole 11 is a stepped hole, including a first diameter section 111 and a second diameter section 112 corresponding to the first threaded section 21 and the second threaded section 22, respectively; the outer diameter of the first threaded section 21 and the outer diameter of the second threaded section 22 are the same, and the inner diameter of the second diameter section 112 is smaller than the inner diameter of the first diameter section 111.

[0062] This is one way to achieve different radial clearances between the two threaded segments and the hole, meaning the two threaded segments have the same outer diameter, but the corresponding inner diameters of the holes are different. Understandably, the outer diameter of the threaded segment here can also be the major diameter.

[0063] In some other embodiments of this application, the first through hole 11 is a cylindrical hole, and the outer diameter of the first threaded section 21 is smaller than the outer diameter of the second threaded section 22.

[0064] This is the second way to achieve different radial clearances between the two threaded segments and the hole, that is, the outer diameters of the two threaded segments are different, while the inner diameters of the holes corresponding to the two threaded segments are the same.

[0065] In other embodiments of this application, reference is made to Figure 5 and Figure 6 The motor shaft 20 includes a shaft body and an oil sealing ring 30. The oil sealing ring 30 is interference-fitted onto the outer circle of the shaft body located inside the first through hole 11. The oil sealing ring 30 has two external threads with different directions of rotation to form the first threaded section 21 and the second threaded section 22.

[0066] The two threads on the motor shaft 20 are achieved by using an oil-sealing ring 30. The oil-sealing ring 30 is an annular sleeve with two threads of different directions machined on its outer surface, and its inner diameter is interference-fitted with the shaft body. This makes machining easier and helps maintain the machining quality of the motor shaft 20, because the motor shaft 20 has high requirements for mechanical properties such as strength and rigidity. Machining threads on the motor shaft 20, both the threads themselves and the machining process, may adversely affect the performance of the motor shaft 20. It is understandable that in some cases, it is also possible to directly machine the threads on the motor shaft 20.

[0067] In other embodiments of this application, reference continues to be made to... Figure 4 and Figure 5 The gearbox 10 includes an intermediate cover 12, which is located at one end of the gearbox 10 near the motor to cover the gearbox 10; the intermediate cover 12 forms the first end wall.

[0068] Understandably, at least one of the various walls of the gearbox 10, such as the end wall, side wall, top wall, or bottom wall, is fixed to the gearbox 10 by means of installation. In this embodiment, the intermediate cover 12 forms the first end wall by installation. Specifically, the installation of the intermediate cover 12 and the other walls of the gearbox 10 maintains a seal, and the intermediate cover 12 does not move; therefore, the sealing method is conventional and effective.

[0069] In other embodiments of this application, reference continues to be made to... Figure 5 and Figure 6The sealing structure further includes a first bearing 40, which is sleeved on the bearing section of the motor shaft 20. The bearing section is located outside the end of the second threaded section 22 away from the first threaded section 21 and is axially connected to the second threaded section 22. The first bearing 40 is interference-fitted with the bearing section.

[0070] In this way, even if a small amount of lubricating oil flows axially toward the bearing under the action of other forces, such as gravity, the lubricating oil cannot flow out due to the interference fit between the bearing and the bearing section.

[0071] Specifically, the motor shaft 20 is also equipped with a shaft retaining ring 41 to position the axial position of the first bearing 40.

[0072] Example 2

[0073] This embodiment provides a sealing structure, see reference. Figure 3 and Figure 4 include:

[0074] The gearbox 10 has a sealed accommodating cavity for accommodating gears; the gearbox 10 also includes a first end wall at one end of the accommodating cavity;

[0075] The motor shaft 20 has one end passing through the first end wall and entering the receiving cavity. The first end wall has a first through hole 11 that mates with the motor shaft 20.

[0076] The motor shaft 20 includes a first threaded section 21 and a second threaded section 22 that are axially connected. Both the first threaded section 21 and the second threaded section 22 are located within the first through hole 11 in the axial direction of the motor shaft 20. The first threaded section 21 is closer to the accommodating cavity than the second threaded section 22. The first threaded section 21 and the second threaded section 22 have different directions of rotation. The thread profile angle of the first threaded section 21 is greater than or equal to 60 degrees, and the thread profile angle of the second threaded section 22 is less than or equal to 55 degrees.

[0077] The difference between this embodiment and Embodiment 1 is that the tooth profile angles of the first thread segment 21 and the second thread segment 22 are different, and there are no requirements for the radial clearance between the thread segment and the first through hole 11; everything else is the same.

[0078] Understandably, the second thread segment 22 has a smaller thread angle, meaning that for the same length, there are more threads, thus generating a greater axial thrust on the lubricating oil. Therefore, it can achieve similar beneficial effects to that of Embodiment 1.

[0079] The sealing structure of this embodiment features a first threaded section 21 and a second threaded section 22 axially connected on the motor shaft 20. The first threaded section 21 and the second threaded section 22 have different rotation directions, and the thread angle of the first threaded section 21 is greater than or equal to 60 degrees, while the thread angle of the second threaded section 22 is less than or equal to 55 degrees. This allows leaked oil to move axially along the direction of the threads. Because the two threads have different rotation directions, there is an axial thrust that prevents oil from flowing out, regardless of whether the rotation is clockwise or counterclockwise. Furthermore, the smaller thread angle of the second threaded section 22 at its outer end generates a greater axial thrust on the lubricating oil, preventing oil from flowing out along the first threaded section 21 and the second threaded section 22, thus providing excellent sealing performance.

[0080] In some other embodiments of this application, the thread of the first threaded segment 21 is a right-hand thread, and the thread of the second threaded segment 22 is a left-hand thread.

[0081] It is understandable that it has similar beneficial effects to Embodiment 1, and will not be described in detail.

[0082] In some other embodiments of this application, the radial clearance between the second threaded segment 22 and the first through hole 11 is greater than 0 mm and less than 0.3 mm.

[0083] Understandably, the radial clearance between the first threaded section 21 and the through hole can be set to be greater than the aforementioned clearance range, for example, greater than 0.3 mm and less than 0.5 mm. This can achieve similar beneficial effects to Embodiment 1, which will not be elaborated further.

[0084] In other embodiments of this application, reference is made to Figure 5 The first through hole 11 is a stepped hole, including a first diameter section 111 and a second diameter section 112 corresponding to the first threaded section 21 and the second threaded section 22, respectively; the outer diameter of the first threaded section 21 and the outer diameter of the second threaded section 22 are the same, and the inner diameter of the second diameter section 112 is smaller than the inner diameter of the first diameter section 111.

[0085] It is understandable that it has similar beneficial effects to Embodiment 1, and will not be described in detail.

[0086] In other embodiments of this application, reference is made to Figure 5 and Figure 6 The motor shaft 20 includes a shaft body and an oil sealing ring 30. The oil sealing ring 30 is interference-fitted onto the outer circle of the shaft body located inside the first through hole 11. The oil sealing ring 30 has two external threads with different directions of rotation to form the first threaded section 21 and the second threaded section 22.

[0087] It is understandable that it has similar beneficial effects to Embodiment 1, and will not be described in detail.

[0088] Understandably, this embodiment has similar settings and beneficial effects to Embodiment 1. For technical details not disclosed in this embodiment, please refer to the description of Embodiment 1 for understanding.

[0089] Example 3

[0090] This application also provides an embodiment of a power tool, see reference. Figure 1 and Figure 2 The power tool includes the sealing structure described in Embodiment 1 or Embodiment 2.

[0091] Specifically, the power tool may be a magnetic drill. Magnetic drills are commonly used for outdoor operations, therefore, preventing lubricating oil leakage from the gearbox 10 is of paramount importance.

[0092] It should be understood that the above embodiments are exemplary and are not intended to encompass all possible implementations included in the claims. Various modifications and changes can be made to the above embodiments without departing from the scope of this application. Similarly, the various technical features of the above embodiments can be arbitrarily combined to form other embodiments of this application that may not be explicitly described. Therefore, the above embodiments merely illustrate several implementations of this application and do not limit the scope of protection of this patent application.

Claims

1. A sealing structure, characterized in that, include: A gearbox having a sealed accommodating cavity for accommodating a gear; the gearbox includes a first end wall at one end of the accommodating cavity; One end of the motor shaft passes through the first end wall and enters the receiving cavity. The first end wall has a first through hole that mates with the motor shaft. The motor shaft includes a first threaded segment and a second threaded segment arranged in sequence. Both the first threaded segment and the second threaded segment are located within the first through hole in the axial direction of the motor shaft. The first threaded segment is closer to the accommodating cavity than the second threaded segment. The first threaded segment and the second threaded segment have different directions of rotation, and the pitch of the second threaded segment is smaller than the pitch of the first threaded segment. The radial clearance between the second threaded segment and the first through hole is smaller than the radial clearance between the first threaded segment and the first through hole.

2. The sealing structure according to claim 1, characterized in that, The first threaded section has a right-hand thread, and the second threaded section has a left-hand thread.

3. The sealing structure according to claim 1, characterized in that, The radial clearance between the second threaded section and the first through hole is greater than 0 mm and less than 0.3 mm.

4. The sealing structure according to any one of claims 1-3, characterized in that, The first through hole is a stepped hole, including a first diameter segment and a second diameter segment corresponding to the first thread segment and the second thread segment, respectively; the outer diameter of the first thread segment and the outer diameter of the second thread segment are the same, and the inner diameter of the second diameter segment is smaller than the inner diameter of the first diameter segment.

5. The sealing structure according to any one of claims 1-3, characterized in that, The first through hole is a cylindrical hole, and the outer diameter of the first threaded section is smaller than the outer diameter of the second threaded section.

6. The sealing structure according to any one of claims 1-3, characterized in that, The motor shaft includes a shaft body and an oil sealing ring. The oil sealing ring is interference-fitted onto the outer circle of the shaft body located within the first through hole. The oil sealing ring has two external threads with different directions of rotation to form the first thread segment and the second thread segment.

7. The sealing structure according to any one of claims 1-3, characterized in that, The gearbox includes an intermediate cover located at one end of the gearbox near the motor to cover the gearbox; the intermediate cover forms the first end wall.

8. The sealing structure according to any one of claims 1-3, characterized in that, The sealing structure further includes a first bearing, which is sleeved on the bearing section of the motor shaft; the bearing section is located outside the end of the second threaded section away from the first threaded section and is axially connected to the second threaded section, and the first bearing is interference-fitted with the bearing section.

9. A sealing structure, characterized in that, include: A gearbox having a sealed accommodating cavity for accommodating a gear; the gearbox further includes a first end wall at one end of the accommodating cavity; One end of the motor shaft passes through the first end wall and enters the receiving cavity. The first end wall has a first through hole that mates with the motor shaft. The motor shaft includes a first threaded segment and a second threaded segment arranged in sequence. Both the first threaded segment and the second threaded segment are located in the first through hole in the axial direction of the motor shaft. The first threaded segment is closer to the accommodating cavity than the second threaded segment. The first threaded segment and the second threaded segment have different directions of rotation. The thread angle of the thread in the first threaded segment is greater than or equal to 60 degrees, and the thread angle of the thread in the second threaded segment is less than or equal to 55 degrees.

10. The sealing structure according to claim 9, characterized in that, The first threaded section has a right-hand thread, and the second threaded section has a left-hand thread.

11. The sealing structure according to claim 9, characterized in that, The radial clearance between the second threaded section and the first through hole is greater than 0 mm and less than 0.3 mm.

12. The sealing structure according to any one of claims 9-11, characterized in that, The first through hole is a stepped hole, including a first diameter segment and a second diameter segment corresponding to the first thread segment and the second thread segment, respectively; the outer diameter of the first thread segment and the outer diameter of the second thread segment are the same, and the inner diameter of the second diameter segment is smaller than the inner diameter of the first diameter segment.

13. The sealing structure according to any one of claims 9-11, characterized in that, The motor shaft includes a shaft body and an oil sealing ring. The oil sealing ring is interference-fitted onto the outer circle of the shaft body located within the first through hole. The oil sealing ring has two external threads with different directions of rotation to form the first thread segment and the second thread segment.

14. A power tool, characterized in that, Includes the sealing structure as described in any one of claims 1-13.

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