A quick-change structure of a bit head of an electric screwdriver offset gear box and the gear box

Abstract

This invention discloses a quick-change bit structure for an electric screwdriver offset gearbox, comprising an output gear, at least one steel ball, a steel ball sleeve, and an elastic reset component. The output gear has an axially penetrating bit mounting hole, and the inner wall of the bit mounting hole has a flat groove for transmitting torque by engaging with the flat part of the bit. The side wall of the output gear has at least one radially penetrating steel ball hole, which communicates with the bit mounting hole. This invention adopts a quick-change principle of steel ball locking and spring automatic reset. The bit can be unlocked by pulling down the steel ball sleeve with one hand, and the bit will automatically lock when the steel ball sleeve is released after inserting a new bit. The entire replacement process requires no auxiliary tools, has a short operation time, and solves the problem of cumbersome replacement of traditional nut structures. It is suitable for continuous operation scenarios that require frequent switching of bit specifications.

Description

Technical Field

[0001] This invention relates to the field of power tool accessories technology, specifically to a quick-change bit structure and gearbox for an electric screwdriver bias gearbox. Background Technology

[0002] In industrial assembly, equipment maintenance, and home renovation, it is common to encounter narrow spaces where there are obstacles above the screw installation location. In such cases, ordinary upright electric or pneumatic screwdrivers cannot directly reach the area to perform the operation. To solve this problem, the industry generally uses an offset gearbox (commonly known as a "Z-gearbox") as an adapter accessory. Through internal gear transmission, the output torque direction of the electric screwdriver is offset by 90°, allowing the bit to extend parallel to the surface of the obstacle below, thus completing the tightening and loosening of screws.

[0003] Currently, all types of offset gearboxes on the market use a traditional nut-locking structure to fix the bit: after the bit shank passes through the bearing at the output end, the bit is axially pressed and fixed by tightening the nut fitted on the output shaft. While this structure is simple, it suffers from the following three insurmountable technical drawbacks in practical use: (1) The bit replacement operation is cumbersome: When replacing bits, you must use a wrench or other auxiliary tools to unscrew the nut, take out the old bit, put in the new bit and tighten the nut again. The whole process takes a long time. In continuous operation scenarios where different bits need to be frequently replaced, it will seriously reduce work efficiency.

[0004] (2) The cutting edge diameter of the bit is strictly limited: In order to prevent the bit from falling out of the bearing hole during operation, the bit shank must be designed with a limiting step with a diameter larger than that of the bearing hole. This structural limitation means that the cutting edge diameter of the bit cannot exceed the diameter of the bearing hole, making it impossible to use large-diameter bits for tightening high-torque or large-size screws, which greatly limits the applicability of the offset gearbox.

[0005] (3) Poor concentricity of the bit rotation: On the one hand, the nut is positioned by a thread, and the clearance of the thread fit will cause radial runout of the bit; on the other hand, the flat groove of the bit used to transmit torque is usually machined by a secondary wire cutting process after the output shaft is machined. The accumulation of machining error and assembly error makes it difficult to achieve ideal concentricity between the bit and the output shaft. The runout of the bit when it rotates at high speed will not only affect the accuracy of screw tightening, but also accelerate the wear of the bit, and even cause the bit to break.

[0006] There is currently no effective solution to the shortcomings of the existing technologies mentioned above. The quick-change mechanism used in conventional upright electric screwdrivers cannot be directly applied to offset gearboxes, mainly because offset gearboxes have limited internal space and require higher standards for airtightness, miniaturization, and transmission stability. Summary of the Invention

[0007] To solve the above-mentioned technical problems, the technical solution provided by the present invention is: a quick-change bit structure for an electric screwdriver bias gearbox, comprising an output gear, at least one steel ball, a steel ball sleeve, and an elastic reset component; The output gear has an axially penetrating bit mounting hole, and the inner wall of the bit mounting hole has a flat groove for transmitting torque by engaging with the flat part of the bit; the side wall of the output gear has at least one radially penetrating steel ball hole, which is connected to the bit mounting hole. The steel ball is radially movable and accommodated within the steel ball hole; the steel ball sleeve is axially slidably sleeved on the outside of the output gear; The elastic reset member is disposed between the output gear and the steel ball sleeve, and is used to apply an axial reset force to the steel ball sleeve; The inner wall of the steel ball sleeve has a locking section and an unlocking section. When the steel ball sleeve is in the locked position, the locking section presses against the steel ball so that it partially extends into the bit mounting hole to engage the steel ball slot of the bit. When the steel ball sleeve is axially pulled to the unlocking position, the unlocking section is opposite to the steel ball hole, and the steel ball can retract outward into the unlocking section to release the bit.

[0008] Preferably, the number of steel ball holes is one, and the steel ball holes are evenly distributed along the circumference of the output gear; one steel ball is disposed in each steel ball hole.

[0009] Preferably, it also includes a retaining ring and a washer, wherein the end of the output gear has an annular groove, the retaining ring is engaged in the annular groove, and the washer is disposed on the side of the retaining ring near the elastic reset member.

[0010] Preferably, the elastic reset element is a spring, which is sleeved on the outside of the output gear, with one end of the spring abutting against the end face of the steel ball sleeve and the other end abutting against the washer.

[0011] Preferably, the unlocking section is provided with a receiving groove corresponding to the steel ball, so that the steel ball is placed in the receiving groove to achieve unlocking.

[0012] Preferably, the two ends of the output gear are rotatably supported in the housing of the bias gearbox by a first bearing and a second bearing, respectively.

[0013] The present invention also discloses an electric screwdriver bias gearbox, including a housing assembly, a transmission assembly, and a quick-change bit structure as described in any one of the claims; The housing assembly includes an upper outer shell and a lower outer shell; The transmission assembly includes an input gear and a driven gear. The input gear is rotatably mounted inside the upper housing, the driven gear is rotatably mounted inside the housing assembly and meshes with the input gear, and the output gear is rotatably mounted inside the lower housing and meshes with the driven gear.

[0014] Preferably, it also includes a locking nut, which is sleeved on the input end of the upper housing and used to lock the bias gearbox to the output end of the electric or pneumatic screwdriver.

[0015] Preferably, the upper outer shell is provided with a quick-connect fitting for vacuuming, and the quick-connect fitting is connected to the internal cavity of the housing assembly.

[0016] The advantages of this invention compared to the prior art are: (1) The present invention adopts the quick-change principle of steel ball locking and spring automatic reset. Only one hand is needed to pull down the steel ball sleeve to unlock the bit. After inserting the new bit, the steel ball sleeve is released to automatically lock. The entire replacement process does not require auxiliary tools and the operation time is short. It solves the problem of cumbersome replacement of traditional nut structure and is suitable for continuous operation scenarios that require frequent switching of bit specifications.

[0017] (2) The present invention achieves axial positioning by using a steel ball to engage the annular groove of the bit handle. The diameter of the bit's cutting edge is no longer limited by the bearing hole size. Bits of different diameters can be selected according to the work requirements, which can meet the needs of large-size screws and high-torque operations, and make the same offset gearbox adaptable to more types of work tasks.

[0018] (3) The quick-change structure of this invention is fully integrated inside the output gear, and the overall axial dimension is basically the same as that of the traditional nut locking structure. There is no need to change the original shape, installation dimensions and transmission parameters of the offset gearbox. The offset gearbox of this invention can directly replace all existing similar products on the market without any modification to the electric screwdriver host, and has excellent backward compatibility.

[0019] (4) The present invention has a vacuum quick-connect interface reserved on the upper shell, which can be connected to an external vacuum source as needed. The negative pressure is formed by the internal cavity of the shell and the hollow bit to realize the automatic adsorption function of the screw. This design is particularly suitable for screw positioning and tightening operations in narrow spaces, further improving the convenience and safety of operation. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the gearbox in this invention.

[0021] Figure 2 This is a schematic diagram of the internal structure of the gearbox in this invention.

[0022] Figure 3 This is a schematic diagram of the quick-change structure in this invention.

[0023] Figure 4 This is a schematic diagram of the quick-change structure of the present invention in conjunction with the bit.

[0024] Figure 5 This is a schematic diagram of the bit's structure.

[0025] 1-Quick-connector for vacuuming; 2-Lock nut; 3-Input gear; 4-Upper housing; 7-Driven gear; 8-First bearing; 9-Output gear; 10-Second bearing; 11-Steel ball; 12-Steel ball sleeve; 13-Washer; 14-Snap ring; 15-Spring; 16-Lower housing; 17-Receiving groove; 901-Bit mounting hole; 902-Flat slot; 903-Steel ball hole. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0027] In the description of the embodiments of the present invention, it should be noted that if terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first," "second," and "third" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0028] Furthermore, the use of terms such as "horizontal," "vertical," and "sag" does not imply that the component must be absolutely horizontal or suspended, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0029] In the description of the embodiments of the present invention, "multiple" means at least two.

[0030] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances. Example

[0031] This invention discloses an overall structure of an electric screwdriver bias gearbox, which includes a housing assembly, a transmission assembly, and a quick-change bit structure. The components are assembled in sequence according to their assembly relationship to achieve quick disassembly and assembly of the bit and stable transmission under bias conditions.

[0032] Specifically, the housing assembly is formed by splicing and fixing the upper outer shell 4 and the lower outer shell 16 together, which together form a closed transmission cavity, providing an installation reference and protection for the transmission assembly and the quick-change bit structure. The input end of the upper outer shell 4 has an external thread, which, together with the locking nut 2, can lock the entire offset gearbox to the output end of the electric or pneumatic screwdriver; during installation, the working angle of the gearbox can be adjusted first, and then the locking nut 2 can be tightened to complete the positioning and fixing. The side wall of the upper outer shell 4 has an interface for installing a quick-connect connector 1 for vacuuming. The quick-connect connector 1 communicates with the internal cavity of the housing. When it is used with adsorption-type hollow bits, an external vacuum source can be connected to form a negative pressure adsorption screw; when the adsorption function is not needed, the interface can be sealed or the quick-connect connector 1 can be removed.

[0033] The transmission assembly is used to transmit torque and includes an input gear 3, a driven gear 7, and an output gear 9. The input gear 3 is rotatably mounted inside the upper housing 4 via bearings, with its upper end extending out of the upper housing 4 and splinedly connected to the output shaft of the electric screwdriver to achieve torque input. The driven gear 7 is rotatably supported in the middle of the housing assembly and meshes with the input gear 3 to complete the first-stage reduction transmission. The output gear 9 is the transmission end and is rotatably mounted on the output end of the lower housing 16 via the first bearing 8 and the second bearing 10. It meshes with the driven gear 7 to complete the second-stage reduction and output torque to the screwdriver bit.

[0034] The quick-change bit structure is located at the output end of the output gear 9 and includes the output gear 9, steel ball 11, steel ball sleeve 12, spring 15, washer 13, and retaining ring 14. The components work together to enable quick tool-free disassembly and assembly of the bit.

[0035] Specifically, the output gear 9 is a cylindrical gear structure with a centrally located, axially penetrating bit mounting hole 901 to accommodate the bit shank. Near the output end, the inner wall of the bit mounting hole 901 has a flat groove 902 that matches the flatness of the bit shank, transmitting torque and preventing circumferential slippage of the bit. Near the output end, the side wall of the output gear 9 has three radially penetrating ball bearing holes 903 evenly spaced along the circumference, which communicate with the bit mounting hole 901. The bit mounting hole 901 of the output gear 9 is integrally machined with the outer cylindrical surface, avoiding secondary machining errors and ensuring the concentricity of the bit mounting.

[0036] Each ball hole 903 contains one ball 11. The diameter of the ball 11 is larger than the axial length of the ball hole 903. It can move freely radially within the ball hole 903 and will not completely detach from the ball hole 903 or fall into the bit mounting hole 901.

[0037] The steel ball sleeve 12 is a cylindrical component that is coaxially slidably sleeved on the outside of the output gear 9. The inner wall is divided into a locking section and an unlocking section. The inner wall of the unlocking section is provided with a receiving groove 17 corresponding to the three steel balls 11. The steel ball sleeve 12 can slide along the axial direction of the output gear 9 to switch between the locking and unlocking positions.

[0038] The output gear 9 has an annular groove at its output end, and the retaining ring 14 is engaged and fixed in the groove; the washer 13 is fitted against the inner end face of the retaining ring 14. The spring 15 is sleeved on the outside of the output gear 9, located between the ball sleeve 12 and the washer 13; one end of the spring 15 abuts against the inner end face of the ball sleeve 12, and the other end abuts against the washer 13, and is always in a pre-compressed state, providing axial restoring force for the ball sleeve 12.

[0039] When installing the screwdriver bit: First, manually pull down the steel ball sleeve 12 to overcome the spring force of the spring 15 and move it axially to the unlocked position. At this time, the receiving groove 17 on the inner wall of the steel ball sleeve 12 is aligned with the steel ball hole 903, the steel ball 11 loses radial constraint and retracts outward into the receiving groove 17, and the bit mounting hole 901 is unobstructed.

[0040] Then, fully insert the bit shank into the bit mounting hole 901, and rotate the bit slightly to make the flat part of the shank fully fit with the flat groove 902; loosen the steel ball sleeve 12, and the spring 15 returns to its original position, pushing the steel ball sleeve 12 to the locking position. The inner wall of the locking section squeezes the steel ball 11, causing part of its spherical surface to be stuck into the pre-set annular groove on the bit shank, restricting the axial movement of the bit, and completing the installation.

[0041] When removing the bit: First, pull down the steel ball sleeve 12 to the unlock position. The steel ball 11 retracts into the receiving groove 17, releasing the engagement with the bit slot. Then, simply pull the bit out to complete the disassembly. No auxiliary tools are needed throughout the process.

[0042] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. A bit quick change structure of an electric screwdriver biasing gear box, characterized in that, It includes an output gear (9), at least one steel ball (11), a steel ball sleeve (12), and a resilient reset element; The output gear (9) has an axially penetrating bit mounting hole (901), and the inner wall of the bit mounting hole (901) has a flat groove (902) for transmitting torque in conjunction with the flat part of the bit; the side wall of the output gear (9) has at least one radially penetrating steel ball hole (903), and the steel ball hole (903) is connected to the bit mounting hole (901). The steel ball (11) is radially movable and accommodated in the steel ball hole (903); the steel ball sleeve (12) is axially slidably sleeved on the outside of the output gear (9); The elastic reset member is disposed between the output gear (9) and the steel ball sleeve (12) and is used to apply an axial reset force to the steel ball sleeve (12); The inner wall of the ball sleeve (12) has a locking section and an unlocking section. When the ball sleeve (12) is in the locked position, the locking section presses against the ball (11) so that part of it extends into the bit mounting hole (901) to engage the ball slot of the bit. When the ball sleeve (12) is axially pulled to the unlocking position, the unlocking section is opposite to the ball hole (903), and the ball (11) can retract outward into the unlocking section to release the bit.

2. The quick-change bit structure according to claim 1, characterized in that, The number of steel ball holes (903) is 3, and the 3 steel ball holes (903) are evenly distributed along the circumference of the output gear (9); a steel ball (11) is correspondingly set in each steel ball hole (903).

3. The quick-change bit structure according to claim 1, characterized in that, It also includes a retaining ring (14) and a washer (13). The end of the output gear (9) is provided with an annular groove. The retaining ring (14) is engaged in the annular groove. The washer (13) is disposed on the side of the retaining ring (14) near the elastic reset member.

4. The quick-change bit structure according to claim 3, characterized in that, The elastic reset element is a spring (15), which is sleeved on the outside of the output gear (9). One end of the spring (15) abuts against the end face of the steel ball sleeve (12), and the other end abuts against the washer (13).

5. The quick-change bit structure according to claim 3, characterized in that, The unlocking section is provided with a receiving groove (17) corresponding to the steel ball (11), so that the steel ball (11) is placed in the receiving groove (17) to achieve unlocking.

6. The quick-change bit structure according to claim 1, characterized in that, The two ends of the output gear (9) are rotatably supported in the housing of the bias gearbox by the first bearing (8) and the second bearing (10), respectively.

7. An electric screwdriver bias gearbox, characterized in that, Includes a housing assembly, a transmission assembly, and a quick-change bit structure as described in any one of claims 1-6; The housing assembly includes an upper outer shell (4) and a lower outer shell (16). The transmission assembly includes an input gear (3) and a driven gear (7). The input gear (3) is rotatably mounted in the upper housing (4). The driven gear (7) is rotatably mounted in the housing assembly and meshes with the input gear (3). The output gear (9) is rotatably mounted in the lower housing (16) and meshes with the driven gear (7).

8. The electric screwdriver offset gearbox according to claim 7, characterized in that, It also includes a locking nut (2), which is fitted onto the input end of the upper housing (4) and is used to lock the bias gearbox to the output end of an electric or pneumatic screwdriver.

9. The electric screwdriver offset gearbox according to claim 7, characterized in that, The upper outer shell (4) is provided with a quick-connect fitting (1) for vacuuming, and the quick-connect fitting (1) is connected to the internal cavity of the shell assembly.

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