Power tool

Abstract

The utility model discloses an electric tool, including casing, transmission shaft, support subassembly and buffer subassembly. Casing is hollowly arranged, and the motor is arranged in it. Transmission shaft is arranged in casing, and one end is drivenly connected with the output shaft of motor, and the other end is from casing and is used for transmission connection work head. Support subassembly is arranged in casing, and is including single bearing structure and double bearing structure. Single bearing structure is arranged between casing and transmission shaft, and is arranged close to motor. Double bearing structure is arranged between casing and transmission shaft, and is arranged close to work head. Buffer subassembly includes first buffer portion that is arranged between single bearing structure and casing and second buffer portion that is arranged between double bearing structure and casing. First buffer portion and second buffer portion are elastically deformed and arranged. Not only can reduce vibration, thereby making electric tool can adapt high operation and strong impact working environment, and can reduce user hand tremor, and promote user experience.

Description

Technical Field

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

[0002] Handheld power tools are small power tools powered by electric motors or electromagnets, driving the working head through a transmission mechanism, and suitable for handheld operation. Taking the straight grinder as an example, straight grinders are widely used for surface treatment of materials such as metal and stone. Typically, when a straight grinder is working, the high-speed rotation of the motor generates vibration, and the operation is often accompanied by radial and axial impact forces. Because the front end of the straight grinder, where the working head is connected, has a grip area for the user, the user experiences noticeable vibrations at the grip area during operation, which can easily lead to fatigue and potentially cause damage to the user's hand joints. Furthermore, to ensure smooth operation, bearings are usually installed at the front end to support the rotation of the output shaft. However, when the high-speed rotating output shaft encounters radial and axial impact forces, the structural strength and installation stability of existing bearings are insufficient to fully adapt to this working environment, and they may even disintegrate, thus shortening the overall service life of the straight grinder. Utility Model Content

[0003] The main purpose of this utility model is to propose a power tool that aims to solve the problem that existing power tools have poor user experience and short lifespan because their internal structure cannot adapt to high-speed and high-impact working environments.

[0004] To achieve the above objectives, this utility model proposes an electric tool, comprising:

[0005] The casing is hollow, and the motor is installed inside.

[0006] A drive shaft is located in the housing, one end of which is driven and connected to the output shaft of the motor, and the other end of which extends out of the housing and is used to drive and connect the working head.

[0007] A support assembly, disposed within the housing, includes a single-bearing structure and a double-bearing structure. The single-bearing structure is located between the housing and the drive shaft, and is positioned close to the motor. The double-bearing structure is located between the housing and the drive shaft, and is positioned close to the working head.

[0008] The buffer assembly includes a first buffer portion disposed between the single bearing structure and the housing, and a second buffer portion disposed between the double bearing structure and the housing, wherein the first buffer portion and the second buffer portion are elastically deformable.

[0009] Preferably, the drive shaft includes a head section, a middle section, and a tail section connected in sequence, the end of the head section is connected to the working head, and the end of the tail section is driven to the output shaft of the motor, wherein:

[0010] The outer diameter of the head section is larger than that of the middle section, and a first stepped surface is formed at the junction of the two. The double bearing structure is disposed in the middle section and abuts against the first stepped surface; and / or,

[0011] The outer diameter of the tail section is smaller than that of the middle section, and a second stepped surface is formed at the connection between the two. The single bearing structure is located in the tail section and abuts against the second stepped surface.

[0012] Preferably, the inner wall of the housing is provided with a first groove at the position corresponding to the single bearing structure, and the first groove extends along the circumference of the housing;

[0013] The first buffer portion is sleeved on the outer periphery of the single bearing structure and is correspondingly pressed against the first groove.

[0014] Preferably, the outer wall of the dual-bearing structure is provided with a second groove along its circumference;

[0015] The second buffer part is fitted onto the second groove and abuts against the inner wall of the housing.

[0016] Preferably, the drive shaft includes a head section that connects to the working head, and the head section is clearance-fitted with the inner wall of the housing;

[0017] The head section has multiple recesses at the overlapping position with the housing, and the multiple recesses are arranged side by side at intervals along the axial direction of the drive shaft.

[0018] Preferably, the head section has multiple annular grooves at the overlapping position with the housing, the multiple annular grooves are arranged side by side at intervals along the axial direction of the drive shaft, and each annular groove extends circumferentially along the head section;

[0019] The recess includes the annular groove.

[0020] Preferably, in the axial direction of the drive shaft, the width of the overlapping portion between the head section and the housing is set to W1, the width of the recess is W2, and the number of recesses is N, wherein 0.4×W1≤W2×N≤0.6×W1; and / or,

[0021] In the radial direction of the transmission shaft, the depth of the recess is set to T, and the wall thickness of the transmission shaft is set to D, wherein 1 / 4×D≤T≤1 / 3×D.

[0022] Preferably, the first buffer portion includes a first elastic washer, which is sleeved on the outer periphery of the single bearing structure and has an interference fit with both the single bearing structure and the housing; and / or,

[0023] The second buffer portion includes a second elastic washer, which is sleeved on the outer periphery of the double bearing structure and has an interference fit with both the double bearing structure and the housing.

[0024] Preferably, the dual-bearing structure includes two bearings arranged side by side along the axial direction of the drive shaft, with the inner ring of the bearing sleeved on the outer circumference of the drive shaft and the outer ring of the bearing fixed to the housing;

[0025] The number of the second elastic washers is 2N, and the multiple second elastic washers are evenly distributed in the two bearings, with each second elastic washer sandwiched between the outer ring of the bearing and the housing.

[0026] Preferably, the power tool further includes a heat insulation sleeve, which is arranged around the outer periphery of the housing corresponding to the drive shaft.

[0027] The technical solution provided by this utility model has at least the following advantages:

[0028] The power tool provided by this utility model has a motor installed inside the housing. The motor's output shaft is connected to a drive shaft, one end of which extends out of the housing and is used to drive the working head. A single-bearing structure and a double-bearing structure are used between the drive shaft and the housing. The end of the drive shaft connected to the motor's output shaft is mainly driven by the rotational power output by the motor, and the radial and axial loads are relatively stable. A single-bearing structure at this position not only meets the support requirements but also saves on the number of bearings and installation space, reducing the overall size and weight of the machine. The end of the drive shaft connected to the working head is subjected to significant radial impact forces during operation. A double-bearing structure at this position provides two-point support, effectively limiting the radial runout of the drive shaft and improving the smoothness of its rotation, reducing vibration, thus enabling the power tool to adapt to high-speed and high-impact working environments. Furthermore, even if one bearing in the double-bearing structure fails, the other bearing can still provide support, thereby increasing the overall service life of the machine. Meanwhile, by setting up the first and second buffer sections, vibration energy can be further absorbed and buffered, thereby reducing the vibration intensity directly transmitted to the casing. This reduces hand vibration when the user holds the casing to perform operations, thus improving the user experience. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0030] Figure 1 A schematic diagram of the structure of an embodiment of an electric tool provided by this utility model;

[0031] Figure 2 for Figure 1 The power tool is shown in a cross-sectional view along AA.

[0032] Figure 3 for Figure 2 An enlarged schematic diagram of part B of the power tool;

[0033] Figure 4 for Figure 1 A schematic diagram of the structure of the power tool (with the head section housing removed);

[0034] Figure 5 for Figure 4 A cross-sectional view of the power tool along the CC direction.

[0035] Explanation of icon numbers:

[0036] 100 Power tool; 1 Housing; 11 Head housing; 12 Main housing; 13 Rear housing; 14 First groove; 2 Motor; 21 Output shaft; 3 Drive shaft; 31 Head section; 311 Working head mounting groove; 32 Intermediate section; 33 Tail section; 331 First section; 332 Second section; 4 Support assembly; 41 Single bearing structure; 42 Double bearing structure; 43 Second groove; 44 First clamp; 45 Second clamp; 5 Buffer assembly; 51 First buffer part; 511 First elastic washer; 52 Second buffer part; 521 Second elastic washer; 6 Recess; 61 Annular groove; 7 Heat insulation sleeve; 8 Coupling; F1 Axial.

[0037] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0038] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0039] It should be noted that if the embodiments of this utility model involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0040] Furthermore, if the embodiments of this utility model involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

[0041] Handheld power tools are small power tools that use an electric motor or electromagnet as power, drive the working head through a transmission mechanism, and are suitable for handheld operation. Taking the straight grinder as an example, straight grinders are widely used for surface treatment of materials such as metal and stone. Typically, when a straight grinder is working, the high-speed rotation of the motor generates vibration, and the operation is often accompanied by radial and axial impact forces.

[0042] In order to enable the power tool 100 to adapt to high-speed and high-impact working environments and to provide users with a better user experience, this utility model improves the structure of the power tool 100. The power tool 100 will be described in detail below with reference to the accompanying drawings.

[0043] Please see Figures 1 to 3 The power tool 100 includes a housing 1, a drive shaft 3, a support assembly 4, and a buffer assembly 5. The housing 1 is hollow and includes a head shell 11, a main shell 12, and a rear shell 13 connected in sequence. A motor 2 is located in the main shell 12. The motor 2 can be a brushless motor or a brushed motor. The output shaft 21 of the motor 2 partially extends into the head shell 11. The drive shaft 3 is located in the head shell 11, with one end connected to the output shaft 21 of the motor 2 for driving, and the other end extending out of the head shell 11 for driving the working head. A circuit board assembly (not shown) is located in the rear shell 13, electrically connected to the motor 2 and controlling its operation. When the power tool 100 is turned on, the output shaft 21 of the motor 2 rotates, driving the working head to rotate via the drive shaft 3 to perform the operation.

[0044] A support assembly 4 is installed inside the housing 1. The support assembly 4 includes a single-bearing structure 41 and a double-bearing structure 42. Understandably, during operation, the drive shaft 3 is connected to one end of the output shaft 21 of the motor 2 and is primarily driven by the rotational power output by the motor 2. Due to the high rotational precision of the motor 2 and its proximity to the motor 2, the impact transmitted to the drive shaft 3 is relatively small, resulting in relatively stable radial and axial loads on the end of the drive shaft 3 near the motor. By installing a single-bearing structure 41 to support the drive shaft 3 at this location, a single bearing is sufficient to meet the support requirements at this position, and it also saves on the number of bearings and installation space, making the connection between the motor 2 and the drive shaft 3 more compact and reducing the overall size and weight of the machine.

[0045] It should be noted that the single bearing structure 41 refers to a structural design in which only one bearing is used in the support system of mechanical transmission or rotating components to achieve radial positioning, axial limiting and load bearing of the rotating shaft.

[0046] Meanwhile, during operation, the working head is in direct contact with the workpiece surface. The eccentric load on the working head and the reaction force when pressing the workpiece will generate significant radial impact and axial thrust on the drive shaft 3. By setting a double bearing structure 42 at the end of the drive shaft 3 away from the motor 2 to support the drive shaft 3, a two-point positioning support is formed. This not only effectively limits the radial runout of the drive shaft 3, but also improves the smoothness of the rotation of the drive shaft 3 and reduces vibration, thus enabling the power tool 100 to adapt to high-operation and high-impact working environments. The double bearing structure 42 can also distribute the load transmitted by the working head, reduce the force on individual bearings, and reduce the risk of bearing wear or disintegration. Furthermore, even if one bearing in the double bearing structure 42 fails, the other bearing can still provide support, thereby improving the service life of the entire machine.

[0047] It should be noted that the dual-bearing structure 42 refers to a structural design in a mechanical transmission or rotating component support system in which two bearings work together to achieve radial positioning, axial limiting, and load bearing of the rotating shaft. The two bearings are usually arranged at intervals along the axis of the shaft, forming a "two-point support".

[0048] In one embodiment, please refer to Figure 2 and Figure 3 The drive shaft 3 includes a head section 31, a middle section 32 and a tail section 33 connected in sequence. The end of the head section 31 is connected to the working head (not shown), and the end of the tail section 33 is driven to the output shaft 21 of the motor 2.

[0049] Specifically, the outer diameter of the head section 31 is larger than that of the middle section 32, and a first stepped surface is formed at the connection between the two. The double bearing structure 42 is located on the middle section 32 and abuts against the first stepped surface. This arrangement can limit the double bearing structure 42 in the axial direction F1 of the drive shaft 3, ensuring the installation stability of the double bearing structure 42. At the same time, a first clamp 44 is fitted on the middle section 32. The first clamp 44 is located on the side of the double bearing structure 42 away from the first stepped surface, so as to press the double bearing structure 42 tightly against the first stepped surface.

[0050] Specifically, the outer diameter of the tail section 33 is smaller than that of the middle section 32, and a second stepped surface is formed at the connection between the two. The single bearing structure 41 is located on the tail section 33 and abuts against the second stepped surface. This arrangement allows the single bearing structure 41 to be positioned in the axial direction F1 of the drive shaft 3, ensuring the installation stability of the single bearing structure 41. At the same time, an annular mounting groove is opened on the inner wall of the housing 1 at the position corresponding to the tail section 33. The mounting groove extends circumferentially along the housing 1, and a second clamp 45 is installed in the mounting groove. The second clamp 45 is located on the side of the single bearing structure 41 facing away from the second stepped surface, so as to press the single bearing structure 41 against the second stepped surface.

[0051] It should be noted that the above two technical features can be set individually or simultaneously. Specifically, in one embodiment, the above two technical features are set simultaneously, that is, the radial dimensions of the sequentially connected head segment 31, middle segment 32 and tail segment 33 are set in descending order, so as to form a first step surface and a second step surface at their connection points, respectively. The double bearing structure 42 and the single bearing structure 41 respectively abut against the first step surface and the second step surface to improve the installation stability of the double bearing structure 42 and the single bearing structure 41.

[0052] Preferably, the tail section 33 further includes a first section 331 and a second section 332 arranged in a stepped shape, with the connection between the two forming a stepped surface. The radial dimension of the first section 331 is larger than the radial dimension of the second section 332. The first section 331 is connected to the middle section 32, and the connection between the two forms a second stepped surface. A sealing ring is fitted on the second section 332, and the sealing ring abuts against the stepped surface. The second section 332 is connected to the output shaft 21 via a coupling 8. A single bearing structure 41 is provided in the first section 331 and abuts against the second stepped surface.

[0053] For preferred options, please refer to [link / reference]. Figure 2 and Figure 3A first buffer section 51 is provided between the single bearing structure 41 and the housing 1, and a second buffer section 52 is provided between the double bearing structure 42 and the housing 1. Since the first buffer section 51 and the second buffer section 52 are elastically deformable, when the drive shaft 3 vibrates, the vibration energy is transmitted to the first buffer section 51 and the second buffer section 52 through the contact surface, forcing both to deform. During the deformation process, the first buffer section 51 and the second buffer section 52 convert some of the vibration energy into their internal elastic potential energy, thereby reducing the vibration intensity directly transmitted to the housing. This reduces hand vibration when the user holds the housing 1, especially the head shell 11, during operation, thus improving the user experience.

[0054] This invention does not impose specific limitations on the number and position of the first buffer section 51. One first buffer section 51 may be provided, or at least two may be provided. Following the above principle that "the local position where the transmission shaft 3 connects to the output shaft 21 of the motor 2 is less affected by impact," it is preferable to provide one first buffer section 51, which reduces the number of first buffer sections 51 while ensuring the buffering effect.

[0055] To ensure a good cushioning effect, the first buffer part 51 is configured as a washer-type product with a relatively large radial thickness. During assembly of the first buffer part 51, a first groove 14 is formed on the inner wall of the housing 1 at the position corresponding to the single bearing structure 41, and the first groove 14 extends circumferentially along the housing 1. The first buffer part 51 is fitted onto the outer periphery of the single bearing structure 41 and pressed against the first groove 14. This configuration ensures the installation stability of the first buffer part 51 and also allows for an interference fit between the first buffer part 51, the single bearing structure 41, and the housing 1.

[0056] Furthermore, given that "the radial thickness of the first buffer part 51 is relatively large", if the first buffer part 51 is installed by slotting on the outer periphery of the single bearing structure 41, it will affect the strength of the single bearing structure 41. However, slotting on the inner wall of the housing 1 will not affect the strength of the single bearing structure 41.

[0057] This invention does not impose specific limitations on the type of the first buffer part 51. Any buffer washer capable of elastic deformation is acceptable.

[0058] In one embodiment, the first buffer portion 51 includes a first elastic washer 511, which is sleeved on the outer periphery of the single bearing structure 41 and has an interference fit with both the single bearing structure 41 and the housing 1.

[0059] Preferably, the first buffer part 51 is an O-ring. The O-ring is made of a high-molecular elastic material such as rubber, which has good elasticity and deformation capacity. When vibration occurs, the O-ring undergoes compression, stretching, or shear deformation. During the deformation process, the molecular chains of the O-ring undergo relative displacement due to the external force, converting some of the vibration energy into elastic potential energy inside the material, thereby reducing the vibration intensity directly transmitted to the housing 1, and the vibration damping effect is obvious.

[0060] This invention does not impose specific limitations on the number and position of the second buffer section 52. At least two second buffer sections 52 are provided. Addressing the aforementioned issue that "the local area where the drive shaft 3 connects to the working head is subjected to significant impact," it is preferable to provide multiple second buffer sections 52, with each multiple second buffer section 52 corresponding to two bearings.

[0061] To ensure effective cushioning, the second buffer portion 52 is configured as a washer-like product with a small radial thickness. During assembly, a second groove 43 is formed along the circumference of the outer wall of the double bearing structure 42; the second buffer portion 52 is fitted into the second groove 43 and abuts against the inner wall of the housing 1. This configuration ensures the installation stability of the second buffer portion 52 and provides an interference fit between the second buffer portion 52, the double bearing structure 42, and the housing 1. Furthermore, because the second buffer portion 52 has a small radial thickness, the groove on the outer circumference of the double bearing structure 42 does not affect its strength.

[0062] This invention does not impose specific limitations on the type of the second buffer part 52. Any buffer washer capable of elastic deformation is acceptable.

[0063] In one embodiment, the second buffer portion 52 includes a second elastic washer 521, which is sleeved on the outer periphery of the double bearing structure 42 and has an interference fit with both the double bearing structure 42 and the housing 1.

[0064] Preferably, the second buffer section 52 also uses an O-ring. The beneficial effects of using an O-ring are the same as those of the first buffer section 51, and will not be repeated here.

[0065] Furthermore, based on the above embodiments, a double bearing structure 42 is provided between the drive shaft 3 and the housing 1 near the working head. The double bearing structure 42 includes two bearings arranged side by side along the axial direction F1 of the drive shaft 3. The inner ring of the bearing is sleeved on the outer circumference of the drive shaft 3, and the outer ring of the bearing is fixed to the housing 1.

[0066] It should be noted that the structures and specifications of the two bearings can be the same or different. In one embodiment, one of the bearings is a deep groove ball bearing, and the other is an angular contact bearing. In another embodiment, the structures and specifications of the two bearings are exactly the same. No specific restrictions are imposed here, and designers can choose according to the specific application scenario.

[0067] Based on this, a second elastic washer 521 is provided between each bearing of the dual bearing structure 42 and the housing 1. Preferably, the number of second elastic washers 521 is 2N, and the multiple second elastic washers 521 are evenly distributed between the two bearings, with each second elastic washer 521 sandwiched between the outer ring of the bearing and the housing 1.

[0068] N is set to 2 to 5. That is, when N is 2, a total of 4 second elastic washers 521 are provided, with two second elastic washers 521 provided for each bearing; when N is 3, three second elastic washers 521 are provided for each bearing; when N is 4, four second elastic washers 521 are provided for each bearing; and when N is 5, five second elastic washers 521 are provided for each bearing.

[0069] Please see Figure 5 Preferably, N is set to 2, and two second elastic washers 521 are provided for each bearing. In this way, the buffering and vibration reduction effect can be guaranteed, and the number of second elastic washers 521 can be reduced.

[0070] Continuing from the previous statement that "the head section 31 is installed through the housing 1 and connected to the working head," the head section 31 is fitted with the inner wall of the housing 1 with a clearance fit to ensure that the drive shaft 3 can rotate. However, during operation, the high-speed rotating drive shaft 3 will generate airflow between its outer wall and the inner wall of the housing 1. This airflow may carry dust into the interior of the housing 1, where it will accumulate at the bearings, thus affecting the service life of the bearings.

[0071] In one embodiment, please refer to Figure 3 and Figure 4 The head section 31 has multiple recesses 6 at its overlap with the housing 1. These recesses 6 are arranged side-by-side at intervals along the axial direction F1 of the drive shaft 3. By providing multiple recesses 6 in the head section 31, not only can the airflow within the gap be turbulent, extending the path and time for dust to reach the bearing inside the housing 1, but it is also equivalent to increasing the accommodating space within the gap between the head section 31 and the housing 1. After dust enters the gap, it will first fill the recesses, thereby blocking the spread path of the dust and reducing the contamination of the internal structure of the housing 1 by the dust.

[0072] Meanwhile, the drive shaft 3 generates heat due to high-speed rotation and friction during operation, which needs to be dissipated through heat exchange with the surrounding air (or cooling fluid). By setting multiple recesses 6, the surface area of ​​the drive shaft 3 is increased, allowing it to make more sufficient contact with the airflow flowing in the gap, thereby accelerating heat transfer, helping to reduce the operating temperature of the drive shaft 3, and preventing overheating from affecting the life of bearings and other components.

[0073] This invention does not impose specific limitations on the formation method of the recess 6. In some embodiments, the recess 6 can be formed between two adjacent protrusions by arranging protrusions at intervals on the outer wall of the head section 31.

[0074] In another embodiment, please refer to Figure 4 and Figure 5 The head section 31 has multiple annular grooves 61 at the overlapping position with the housing 1. The multiple annular grooves 61 are arranged side by side at intervals along the axial direction F1 of the drive shaft 3, and each annular groove 61 extends circumferentially along the head section 31; wherein, the recess 6 includes annular grooves 61.

[0075] Considering the small gap between the head section 31 and the inner wall of the housing 1, in order to avoid the recess 6 affecting the clearance fit between the head section 31 and the inner wall of the housing 1, in this embodiment, an annular groove 61 is formed on the outer wall of the head section 31 to create the recess 6. Furthermore, compared to setting protrusions on the outer wall of the head section 31, the process of creating a groove on the outer wall of the head section 31 is simpler and easier to manufacture.

[0076] To ensure dustproof performance, please refer to the following for details. Figure 4 and Figure 5 On the axial direction F1 of the drive shaft 3, the width of the overlapping portion between the head section 31 and the housing 1 is set to W1, the width of the recess 6 is W2, and the number of recesses 6 is N, where 0.4×W1≤W2×N≤0.6×W1. In this way, the path and time for dust to reach the bearing inside the housing 1 can be extended as much as possible.

[0077] Since the recess 6 is formed by slotting the outer wall of the head section 31, in order to ensure the strength of the head section 31, please refer to [specific details]. Figure 4 and Figure 5 In the radial direction of the drive shaft 3, the depth of the recess 6 is set to T, and the wall thickness of the drive shaft 3 is set to D, where 1 / 4×D≤T≤1 / 3×D. It should be noted that the center of the end face away from the motor in the head section is recessed along the direction towards the motor to form a closed working head mounting groove 311. The wall thickness of the drive shaft refers to the wall thickness at the non-closed end of the working head mounting groove 311 where the recess 6 is located. In this way, sufficient space is provided for dust to be contained without affecting the strength of the drive shaft 3.

[0078] It should be noted that the above two technical features can be set individually or simultaneously. Specifically, in one embodiment, both technical features are set simultaneously.

[0079] This invention does not limit the cross-sectional shape of the annular groove 61. The cross-section of the annular groove 61 can be semi-circular, square, or triangular.

[0080] Typically, for handheld power tools 100, a gripping area is directly provided on the housing 1. Taking a straight mill as an example, the gripping part is usually set directly on a local area of ​​the housing 1 near the working head, allowing the user to grip this area for operation. Since the drive shaft 3 is located in the corresponding area inside the housing 1, the drive shaft 3 generates heat due to high-speed rotation and friction during operation, thus the corresponding area of ​​the housing 1 is prone to overheating.

[0081] To prevent the heat generated by the housing 1 during operation from affecting the user's grip, in one embodiment, the power tool 100 further includes a heat insulation sleeve 7, which is arranged around the outer periphery of the housing 1 corresponding to the drive shaft 3. This reduces heat transfer to the grip area, thereby improving the user's operating experience.

[0082] The above description is only a preferred embodiment of the present utility model and does not limit the patent scope of the present utility model. All equivalent structural transformations made under the concept of the present utility model and using the contents of the present utility model specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present utility model.

Claims

1. A power tool, characterized in that, include: The casing is hollow, and the motor is installed inside. A drive shaft is located in the housing, one end of which is driven and connected to the output shaft of the motor, and the other end of which extends out of the housing and is used to drive and connect the working head. A support assembly, disposed within the housing, includes a single-bearing structure and a double-bearing structure. The single-bearing structure is located between the housing and the drive shaft, and is positioned close to the motor. The double-bearing structure is located between the housing and the drive shaft, and is positioned close to the working head. The buffer assembly includes a first buffer portion disposed between the single bearing structure and the housing, and a second buffer portion disposed between the double bearing structure and the housing, wherein the first buffer portion and the second buffer portion are elastically deformable.

2. The power tool according to claim 1, characterized in that, The drive shaft includes a head section, a middle section, and a tail section connected in sequence. The end of the head section is connected to the working head, and the end of the tail section is driven to the output shaft of the motor, wherein: The outer diameter of the head section is larger than that of the middle section, and a first stepped surface is formed at the junction of the two. The double bearing structure is disposed in the middle section and abuts against the first stepped surface; and / or, The outer diameter of the tail section is smaller than that of the middle section, and a second stepped surface is formed at the connection between the two. The single bearing structure is located in the tail section and abuts against the second stepped surface.

3. The power tool according to claim 1, characterized in that, The inner wall of the housing has a first groove at the position corresponding to the single bearing structure, and the first groove extends circumferentially along the housing. The first buffer portion is sleeved on the outer periphery of the single bearing structure and is correspondingly pressed against the first groove.

4. The power tool according to claim 1, characterized in that, The outer wall of the dual bearing structure is provided with a second groove along its circumference; The second buffer part is fitted onto the second groove and abuts against the inner wall of the housing.

5. The power tool according to claim 1, characterized in that, The drive shaft includes a head section that connects to the working head, and the head section is clearance-fitted with the inner wall of the housing; The head section has multiple recesses at the overlapping position with the housing, and the multiple recesses are arranged side by side at intervals along the axial direction of the drive shaft.

6. The power tool according to claim 5, characterized in that, The head section has multiple annular grooves at the overlapping position with the housing. The multiple annular grooves are arranged side by side at intervals along the axial direction of the drive shaft, and each annular groove extends circumferentially along the head section. The recess includes the annular groove.

7. The power tool according to claim 6, characterized in that, Along the axial direction of the drive shaft, the width of the overlapping portion between the head section and the housing is set to W1, the width of the recess is W2, and the number of recesses is N, wherein 0.4×W1≤W2×N≤0.6×W1; and / or, In the radial direction of the transmission shaft, the depth of the recess is set to T, and the wall thickness of the transmission shaft is set to D, wherein 1 / 4×D≤T≤1 / 3×D.

8. The power tool according to claim 1, characterized in that, The first buffer portion includes a first elastic washer, which is sleeved on the outer periphery of the single bearing structure and has an interference fit with both the single bearing structure and the housing; and / or, The second buffer portion includes a second elastic washer, which is sleeved on the outer periphery of the double bearing structure and has an interference fit with both the double bearing structure and the housing.

9. The power tool according to claim 8, characterized in that, The dual-bearing structure includes two bearings arranged side by side along the axial direction of the drive shaft, with the inner ring of the bearing sleeved on the outer circumference of the drive shaft and the outer ring of the bearing fixed to the housing. The number of the second elastic washers is 2N, and the multiple second elastic washers are evenly distributed in the two bearings, with each second elastic washer sandwiched between the outer ring of the bearing and the housing.

10. The power tool according to claim 1, characterized in that, The power tool also includes a heat insulation sleeve, which is arranged around the outer periphery of the housing corresponding to the drive shaft.

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