A function switching mechanism of an electric drill

Abstract

The utility model discloses a function switching mechanism of electric drill for switching the working mode of electric drill between the drilling mode and the screwdriver mode. The electric drill comprises a shell, a planetary gear train, an inner ring gear and a skip mechanism. The function switching mechanism adopts a structure design of circumferential driving shaft moving, axial driving radial locking. The mechanism comprises a function ring, a pre-press seat, a locking piece and a limiting piece (steel ball). The function ring is matched with the protruding part / recess part of the pre-press seat through its lug, and converts the circumferential rotation into the axial displacement of the pre-press seat and the locking piece. A pre-press elastic piece is arranged between the pre-press seat and the locking piece to provide axial buffering. The circumferential surface of the locking piece is provided with a reduced diameter section and a transition inclined surface. In the drilling mode, the reduced diameter section of the locking piece forcibly pushes the limiting piece radially into the groove of the inner ring gear, realizing the circumferential forced locking of the inner ring gear. This structure effectively overcomes the "drilling skip" problem easily caused by the traditional axial limiting, and improves the reliability of the electric drill under high load working conditions.

Description

Technical Field

[0001] This utility model relates to the field of power tool technology, specifically to a function switching mechanism for an electric drill. Background Technology

[0002] In existing technologies, the mode switching of dual-mode or multi-mode electric drills is typically achieved by controlling the motion of the internal gear ring in a planetary gear train. In drilling mode, the internal gear ring must be completely locked relative to the drill housing to ensure that the motor power can be output at a constant transmission ratio. In screwdriver mode, the internal gear ring needs to be allowed to rotate relative to the housing within a preset torque limit value to prevent overload and protect the workpiece.

[0003] However, traditional locking structures, such as those applying friction or axial meshing locking force to the end face of the internal gear ring through axial pressure, exhibit significant drawbacks under high-load conditions. When an electric drill performs high-torque, high-load drilling operations, a large axial reaction force is generated within the planetary gear train. This reaction force often causes slight axial deformation or displacement of the drill housing or internal limiting support components. Axial displacement can instantly weaken or even negate the axial preload originally used for locking, causing the internal gear ring to be released unexpectedly, resulting in circumferential rotation, or "drilling gear skipping." This problem not only leads to drilling interruptions and low efficiency but also accelerates the wear of transmission components, severely affecting the product quality and service life of the electric drill. Furthermore, the torque limiting accuracy and stability of axial friction locking are easily affected by temperature changes and fluctuations in the coefficient of friction. Therefore, there is an urgent market demand for a new switching mechanism that is simple in structure, provides high strength and reliable radial locking, and eliminates drilling gear skipping. Utility Model Content

[0004] To solve the above problems, this utility model provides a function switching mechanism for an electric drill.

[0005] To achieve the above objectives, the technical solution of this utility model is as follows: A function switching mechanism for an electric drill, the electric drill comprising a housing, a planetary gear train, and an output shaft, the planetary gear train having an internal gear ring that can selectively restrict rotation, the outer circumference of the internal gear ring having a plurality of grooves; the function switching mechanism includes: A functional ring is rotatably disposed on the housing in the circumferential direction, and the end face of the functional ring is provided with a protrusion; A preload seat is movably disposed along the axial direction, and the end face of the preload seat is provided with a protrusion and a recess that circumferentially cooperate with the protrusion; A locking member is installed axially within the preload seat, the circumferential surface of the locking member having a reduced diameter section and a transition slope; A preload elastic element positioned axially between the preload seat and the locking member; A limiting member is arranged radially and housed within the radial accommodating space of the housing, the limiting member being radially extendable into the groove of the internal gear ring.

[0006] Furthermore, the preload seat is provided with a preload groove along the axial direction, the locking member is installed in the preload groove along the axial direction, the preload elastic member abuts against the preload seat and the locking member along the axial direction, and the transition slope of the locking member is located at the end of the reduced diameter section away from the functional ring in the axial direction.

[0007] Furthermore, the function switching mechanism also includes a limiting elastic element, which is supported by the axial support surface on the housing and abuts against the preload seat axially.

[0008] Furthermore, when the functional ring rotates to the drilling mode position, the reduced diameter section of the locking member is axially positioned radially outside the limiting member, and the radial dimension of the reduced diameter section abuts radially against the limiting member, thereby radially pushing the limiting member into the groove to achieve circumferential locking of the internal gear ring.

[0009] Furthermore, when the functional ring rotates to the screwdriver mode position, the transition slope of the locking member is axially positioned on the radially outer side of the limiting member. The transition slope allows the limiting member to radially disengage from the groove under torque, thereby releasing the circumferential limit of the internal gear ring.

[0010] Furthermore, the limiting element is a steel ball, and there are at least two of them, and the number of grooves on the internal gear ring matches the number of the limiting elements.

[0011] Furthermore, the shift mechanism of the electric drill includes a shift pin, a shift washer, and a shift elastic element; the shift elastic element is arranged axially, and the shift washer abuts against the shift pin axially, and the end of the shift pin abuts against the end of the internal gear ring axially.

[0012] Furthermore, the end of the internal gear ring is provided with a protrusion corresponding to the inclined surface of the end of the skip pin.

[0013] The advantages of this utility model over the prior art are as follows: This invention employs radial forced locking, which completely solves the problem of "drilling skipping gears" and improves the service life and reliability of the electric drill under high load conditions. Furthermore, the axial preload and buffering effect provided by the preload elastic element in this invention ensures smooth and accurate positioning of the functional ring during switching. In addition, the components of this invention are highly integrated, integrating multiple functions such as circumferential selection, axial drive, radial locking, and internal preload while maintaining a compact structure. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of the electric drill gearbox in an embodiment of this utility model; Figure 2 This is an exploded view of the electric drill gearbox in an embodiment of the present invention; Figure 3 This is a cross-sectional view of the electric drill in screwdriver mode in an embodiment of the present invention; Figure 4 This is a cross-sectional view of the electric drill in drilling mode (pre-pressure position) in an embodiment of the present invention; Figure 5 This is a cross-sectional view of the electric drill in drilling mode (clamping position) in an embodiment of the present invention; Figure 6 This is a schematic diagram of the assembly of the skip-gear assembly and the pre-pressing assembly in an embodiment of this utility model; Figure 7 This is an assembly diagram of the skip-gear assembly and the pre-pressurization assembly in an embodiment of the present invention (the housing is not shown). Figure 8 This is a schematic diagram of the structure when the locking member presses the limiting member into the groove in an embodiment of the present invention; Figure 9 This is a schematic diagram of the locking component in an embodiment of the present utility model; Figure 10 This is a schematic diagram of the pre-compression component in an embodiment of the present invention; Figure 11 This is a schematic diagram of the assembly of the switching ring and the pre-pressure seat in an embodiment of this utility model.

[0015] In the picture: 1. Function switching component; 11. Function ring; 12. Bump; 2. Preload assembly; 21. Preload seat; 211. Protrusion; 212. Recess; 213. Preload groove; 22. Locking element; 221. Reduction section; 222. Transition slope; 23. Preload elastic element; 24. Limiting elastic element; 3. Limiting components; 4. Shell; 5. Internal gear ring; 51. Groove; 52. Protrusion; 6. Gear shifting mechanism; 61. Gear shifting pin; 62. Gear shifting washer; 63. Gear shifting elastic element. Detailed Implementation

[0016] 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. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present utility model or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0017] Those skilled in the art will understand that, without conflict, the features in the following embodiments and implementations can be combined with each other.

[0018] The terminology used in this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. For example, terms such as "upper," "lower," "front," and "rear," which indicate orientation or positional relationship, are based solely on the orientation or positional relationship shown in the accompanying drawings and are used only for the convenience of describing the invention and simplifying the description. They do not indicate or imply that the device / component referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention.

[0019] As used herein, the singular forms “a,” “an,” and “the” include plural objects, and the plural form “multiple” includes two or more objects, unless otherwise expressly indicated. As used herein, the term “or” is generally used to include the meaning of “and / or,” unless otherwise expressly indicated, and the terms “install,” “connect,” and “link” should be interpreted broadly, for example, as a fixed connection, a detachable connection, or an integral connection. Connections can be direct or indirect through an intermediate medium, and can be internal communication between two components or an interaction between two components.

[0020] Please refer to Figure 1-11This utility model provides a function switching mechanism for an electric drill, including a function switching component 1, a preload component 2, and a limiting member 3. The function switching mechanism is located at the front of the electric drill gearbox and mainly interacts with the internal gear ring 5 of the planetary gear train. The outer circumference of the internal gear ring 5 has grooves 51 evenly distributed circumferentially to accommodate the limiting member 3. The function switching component 1 includes a function ring 11 and a protrusion 12, which are installed on the outside of the electric drill housing 4. Mode selection is achieved by circumferential rotation of the user's hand, and its outer circumference has anti-slip textures for user operation. The preload component 2 includes a preload seat 21, a locking member 22, and a preload elastic member 23. The preload seat 21 is held against the stepped surface of the housing 4 by the limiting elastic member 24. The side of the preload seat near the function ring 11 has a protrusion 211 and a recess 212, which cooperate with the protrusion 12 on the function ring 11.

[0021] The protrusion 12 on the inner end face of the functional ring 11 serves as the main driving element. Its shape and slope are optimized to ensure stable contact with the protrusion 211 and recess 212 on the end face of the preload seat 21 during circumferential rotation, and to efficiently convert the circumferential force into axial thrust along the output shaft axis of the electric drill. The slope angle between the protrusion 211 and the recess 212 determines the proportional relationship between the operating force and axial displacement required for mode switching.

[0022] Please refer to Figure 2-5 The preload assembly 2 and the locking member 22 are arranged along the axis of the electric drill and are driven by the axial thrust of the functional ring 11. A preload groove 213 is provided inside the preload seat 21, and the locking member 22 is slidably installed within the preload groove 213. The preload elastic member 23 is compressed and positioned between the preload seat 21 and the locking member 22, providing a continuous axial preload force to the locking member 22. This preload force ensures that the preload seat 21 and the locking member 22 do not loosen during axial movement, acting as a rigid body driven by the functional ring 11. Furthermore, when the functional ring 11 rotates to switch modes, if the radial position of the limiting member 3 is disturbed by the circumferential position of the internal gear ring 5 and cannot retract in time (i.e., not aligned with the groove 51), the axial compression of the preload elastic member 23 allows the functional ring 11 to continue rotating, eliminating any jamming sensation. Once the internal gear ring 5 rotates into position or the limiting member 3 aligns with the groove 51, the restoring force of the preload elastic member 23 instantly drives the locking member 22 to complete the final locking action.

[0023] The limiting element 3 is preferably a steel ball made of a highly wear-resistant material. To distribute stress, it is preferable to use two or more steel balls, which are evenly distributed circumferentially within the radial accommodating space of the housing 4, radially aligned with the groove 51 of the internal gear ring 5. The diameter of the radial accommodating space (through hole) is precisely designed to ensure that the steel balls can only move radially and cannot move circumferentially or axially.

[0024] The locking member 22 includes a reduced-diameter section 221 and a transition slope 222 arranged axially. The reduced-diameter section 221 is located at the upper end of the locking member 22 and has a smaller radial dimension. When it contacts the limiting member 3, it applies sufficient radial thrust to the limiting member 3, forcibly pushing it into the groove 51 of the internal gear ring 5. The transition slope 222 is located at the lower end of the locking member 22, and its slope is calculated to guide the limiting member 3 out of the groove 51 in screwdriver mode, thereby achieving torque limiting.

[0025] Please refer to Figure 4-5 During drilling mode, the functional ring 11 drives the locking member 22 to move axially to the locked position. The reduced diameter section 221 of the locking member 22 is axially positioned radially outside the limiting member 3, and the provided radial thrust securely locks the limiting member 3 into the groove 51 of the internal gear ring 5. At this time, the internal gear ring 5 is reliably radially fixed, and the circumferential locking force is different from the traditional axial locking force, and its ability to resist axial reaction force is extremely strong.

[0026] Please refer to Figure 3 When operating in screwdriver mode, the functional ring 11 drives the locking member 22 to move axially to the release position. The transition slope 222 of the locking member 22 is axially positioned radially outward of the limiting member 3, at which point the radial constraint force of the limiting member 3 is weakened. When the output torque reaches the preset value, the protrusion 52 of the internal gear ring 5 overcomes the preload force of the shift mechanism 6 and rotates, and the limiting member 3 moves radially outward along the direction of the transition slope 222, releasing the lock on the internal gear ring 5.

[0027] The shift mechanism 6 includes a shift pin 61, a shift washer 62, and a shift elastic element 63. The shift pin 61 has a cylindrical structure with a spherical end to reduce friction with the internal gear ring 5. The number of shift pins 61 corresponds to the number of protrusions 52 on the internal gear ring 5, typically 3-6, evenly distributed along the circumference. The contact surface between the protrusions 52 at the end of the internal gear ring 5 and the end of the shift pin 61 has a precise bevel structure. The shift elastic element 63 uses a disc spring or a coil spring to provide the necessary pressure to maintain contact between the shift pin 61 and the internal gear ring 5. The preload of the shift elastic element 63 is transmitted to the shift pin 61, which abuts against the end of the internal gear ring 5. During operation, the interaction force between the shift pin 61 and the protrusions 52 is decomposed into axial and circumferential components. When the output shaft of the electric drill encounters significant resistance, the circumferential torque increases. When the corresponding axial component force exceeds the preload of the shifting elastic element 63, the shifting pin 61 is axially pushed open, thereby realizing the rotation of the internal gear ring 5 and shifting.

[0028] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Those skilled in the art should understand that this utility model includes, but is not limited to, the content described in the above specific embodiments. Any modifications that do not depart from the functional and structural principles of this utility model will be included within the scope of the claims.

Claims

1. A function switching mechanism for an electric drill, the electric drill comprising a housing, a planetary gear train, and an output shaft, the planetary gear train having an internal gear ring that can selectively restrict rotation, the outer circumference of the internal gear ring having a plurality of grooves; characterized in that, The function switching mechanism includes: A functional ring is rotatably disposed on the housing in the circumferential direction, and the end face of the functional ring is provided with a protrusion; A preload seat is movably disposed along the axial direction, and the end face of the preload seat is provided with a protrusion and a recess that circumferentially cooperate with the protrusion; A locking member is installed axially within the preload seat, the circumferential surface of the locking member having a reduced diameter section and a transition slope; A preload elastic element positioned axially between the preload seat and the locking member; A limiting member is arranged radially and housed within the radial accommodating space of the housing, the limiting member being radially extendable into the groove of the internal gear ring.

2. The function switching mechanism according to claim 1, characterized in that: The preload seat is provided with a preload groove along the axial direction, the locking member is installed in the preload groove along the axial direction, the preload elastic member abuts against the preload seat and the locking member along the axial direction, and the transition slope of the locking member is located at the end of the reduced diameter section away from the functional ring in the axial direction.

3. The function switching mechanism according to claim 1, characterized in that: The function switching mechanism also includes a limiting elastic element, which is supported by the axial support surface on the housing and abuts against the preload seat axially.

4. The function switching mechanism according to claim 1, characterized in that: When the functional ring rotates to the drilling mode position, the reduced diameter section of the locking member is positioned axially on the radial outside of the limiting member. The radial dimension of the reduced diameter section abuts against the limiting member radially, pushing the limiting member radially into the groove to achieve circumferential locking of the internal gear ring.

5. The function switching mechanism according to claim 1, characterized in that: When the functional ring rotates to the screwdriver mode position, the transition slope of the locking member is axially positioned on the radially outer side of the limiting member. The transition slope allows the limiting member to radially disengage from the groove under torque, thereby releasing the circumferential limit of the internal gear ring.

6. The function switching mechanism according to claim 1, characterized in that: The limiting element is a steel ball, and there are at least two of them. The number of grooves on the internal gear ring matches the number of the limiting elements.

7. The function switching mechanism according to claim 1, characterized in that: The shift mechanism of the electric drill includes a shift pin, a shift washer, and a shift elastic element; the shift elastic element is arranged axially, and the shift washer abuts against the shift pin axially, and the end of the shift pin abuts against the end of the internal gear ring axially.

8. The function switching mechanism according to claim 7, characterized in that: The end of the internal gear ring is provided with a protrusion corresponding to the inclined surface of the end of the skip pin.

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