A portable electric scissors

Abstract

The utility model discloses a portable electric scissors, including support, with the fixed connection of support fixed knife, with the pivotal axis rotation connection of support and the driving piece of power source of movable knife, still include: the input of reduction gear is connected with the output shaft transmission of driving piece, and transmission mechanism, transmission mechanism includes: worm, with support rotation is connected, and its one end is connected with the output transmission of reduction gear, worm wheel, with support rotation is connected, and is engaged with worm, eccentric wheel, with coaxial fixed connection of worm wheel, and connecting rod, one end with movable knife eccentric rotation is connected, the other end with eccentric wheel eccentric rotation is connected, the axis of worm is perpendicular and meets first plane with pivotal axis, and the rotation axis of worm wheel is offset a preset distance to first plane. The utility model discloses low noise, and good reliability.

Description

Technical Field

[0001] This utility model relates to the field of electric scissors technology, specifically to a portable electric scissors. Background Technology

[0002] Electric pruning shears, especially portable electric pruning shears, are widely used due to their ease of operation and high efficiency. Their core transmission system needs to convert the high-speed rotation of the motor into the low-speed, high-torque reciprocating cutting motion of the blades, which usually involves multi-stage reduction and 90-degree reversal.

[0003] In existing technologies, a common solution to achieve the above functions is to use a "bevel gear transmission structure." This solution typically utilizes a bevel gear pair to change the direction of power transmission. Specifically, after necessary reduction, the motor output is redirected by a pair of bevel gears to change the direction of the power shaft by approximately 90 degrees, ultimately driving the blade to perform the shearing operation.

[0004] However, the aforementioned transmission structure with bevel gears as the core reversing component has significant technical defects: First, the noise level is too high. Because bevel gear pairs are line contact meshing, they are prone to impact during transmission, resulting in significant operating noise. The noise level of the entire machine can typically reach 68-72 dB(A) or higher, becoming the main noise source of the machine and seriously affecting the user experience.

[0005] Secondly, there is a risk of tooth skipping and cascading damage. Pruning shears are subjected to sudden and severe impact loads due to changes in plant diameter during operation, reaching 2 to 3 times the normal load. Under such impact, the meshing backlash of the bevel gear pair can easily cause gear disengagement (i.e., "tooth skipping"). The rebound impact force generated by tooth skipping is transmitted back to the transmission system, potentially causing gear tooth breakage and other malfunctions, significantly reducing the reliability and service life of the transmission system.

[0006] Therefore, there is an urgent need in this field for a new transmission solution to solve the problems of high noise and easy tooth skipping caused by the use of bevel gear pairs in the prior art, while achieving a compact structural layout. Utility Model Content

[0007] The present invention aims to provide a portable electric scissors that operates more smoothly and with less noise.

[0008] To achieve the above objectives, this utility model provides a portable electric scissors, including a bracket, a fixed blade fixedly connected to the bracket, a movable blade rotatably connected to the bracket via a pivot axis, and a driving component as a power source; it also includes a transmission mechanism, the transmission mechanism comprising: The worm gear is rotatably connected to the bracket, and one end of it is driven to the output shaft of the drive component. The worm gear is rotatably connected to the support and meshes with the worm. An eccentric wheel, coaxially and fixedly connected to the worm gear; and The connecting rod is eccentrically connected at one end to the moving blade and eccentrically connected at the other end to the eccentric wheel. The worm's axis intersects the pivot axis perpendicularly to define a first plane, and the worm wheel's rotation axis is offset by a predetermined distance relative to the first plane.

[0009] By adopting the above technical solution, the continuous helical meshing characteristics of the worm gear pair are utilized to eliminate the line contact impact of traditional bevel gear transmissions, reducing the overall machine operating noise to a low level (below 60dB in internal testing). Simultaneously, its inherent high transmission ratio ensures the system achieves low-speed, high-torque output. Offsetting the worm gear's rotation axis outside the first plane defined by the worm axis and the cutter shaft (pivot axis) breaks the limitation of the traditional coplanar layout of transmission components. This three-dimensional offset design allows for a more flexible and compact arrangement of the motor, reducer, and other drive modules along the handle's length, effectively utilizing the handle's internal space and creating conditions for miniaturization and slenderness of the tool, while avoiding motion interference between components.

[0010] Furthermore, the rotation axis of the worm gear is offset by the preset distance in a direction parallel to the pivot axis.

[0011] By adopting the above technical solution, the specific direction of the offset is clarified, ensuring the parallel relationship between the worm gear axis and the moving tool pivot axis. This makes the subsequent eccentric wheel-linkage mechanism's motion trajectory clear and the force transmission path direct. This parallel offset facilitates machining and assembly, ensures the symmetry and stability of the mechanism's motion, and further optimizes the space utilization of the internal structure.

[0012] Furthermore, let L1 be the distance between the axis connecting the connecting rod and the moving blade and the axis connecting the connecting rod and the eccentric wheel, and L2 be the distance between the axis connecting the moving blade and the connecting rod and the pivot axis. Then the following relationship is satisfied: L1 > L2.

[0013] By adopting the above technical solution, and by limiting the length of the connecting rod L1 to be greater than the moving blade lever arm L2, a lever ratio that is conducive to torque amplification is constructed. During the moving blade shearing process, this proportional relationship allows the force transmitted from the drive component to the moving blade through the connecting rod to be effectively amplified, thereby obtaining a larger output shearing force with a smaller input torque, improving the cutting ability of the shears, and allowing for smaller and more energy-efficient drive component selection.

[0014] Furthermore, if the distance between the axis connecting the connecting rod and the eccentric wheel and the axis of rotation of the eccentric wheel is defined as L3, then the relationship L2 > L3 is further satisfied.

[0015] By adopting the above technical solution, the moving tool lever arm L2 is further limited to be greater than the eccentricity L3 of the eccentric wheel, forming an optimized dimensional chain of L1>L2>L3. This design ensures that the oscillation amplitude of the mechanism on the moving tool (load) side is greater than the eccentricity amplitude on the drive side (eccentric wheel), achieving "buffering" and "stabilization" of the motion. The smaller L3 helps reduce vibration when the eccentric wheel rotates at high speed, while L2>L3 ensures that the moving tool has sufficient working stroke, while making the transmission process smoother and reducing impact and noise.

[0016] Furthermore, the moving blade has a closed position close to the fixed blade and an open position away from the fixed blade. The moving blade rotates between the closed position and the open position. During the rotation of the moving blade, the axis of rotation between the connecting rod and the moving blade is always located on the same side of the first plane.

[0017] By adopting the above technical solution, the motion trajectory of the connection point between the connecting rod and the moving tool is spatially constrained, ensuring that it remains on the same side of the fixed plane throughout the working cycle. This avoids abrupt changes in force direction and dead points that may occur when the connection point crosses the plane, ensuring that the direction of the transmitted force is always consistent and controllable. This significantly improves the smoothness and reliability of the mechanism's motion and reduces the risk of wear and jamming.

[0018] Furthermore, during the rotation of the moving blade, the axis connecting the connecting rod to the moving blade and the axis connecting the connecting rod to the eccentric wheel are both located on the same side of the first plane.

[0019] By adopting the above technical solution, the connection points at both ends of the connecting rod are constrained to the same side of the "first plane," meaning that the entire connecting rod remains in a relatively stable spatial posture during operation. This constraint allows the connecting rod to primarily bear tensile and compressive stresses, greatly reducing the lateral bending moment and additional loads caused by oscillation, further optimizing the stress state of the rod, improving transmission efficiency, and making the structure operate more quietly and stably.

[0020] Furthermore, as the moving blade rotates from the open position to the closed position, the angle formed by connecting the projection points of the connecting axis between the connecting rod and the eccentric wheel, the connecting axis between the connecting rod and the moving blade, and the pivot axis on a plane perpendicular to the pivot axis gradually decreases.

[0021] By adopting the above technical solution, this included angle can be regarded as the transmission pressure angle, and its gradual reduction is a dynamic optimization process. In the initial stage of shearing (open position), the larger pressure angle allows the moving blade to quickly approach the workpiece; while in the final stage of shearing (closed position), the pressure angle is reduced to a minimum, at which point the direction of force transmission is most conducive to overcoming material resistance, and the transmission efficiency is the highest. This "fast first, then force" characteristic makes the shears move rapidly during idle strokes and achieve the highest mechanical efficiency when the shearing load is at its maximum, thus achieving a good balance between efficiency and capacity.

[0022] Furthermore, it also includes a speed reducer, the input end of which is drivenly connected to the output shaft of the drive unit, and its output end is drivenly connected to a worm gear, wherein the speed reducer is a planetary gear reducer.

[0023] By adopting the above technical solution, a planetary gear reducer is used as the primary reduction mechanism, which has the advantages of compact structure, large transmission ratio, strong load-bearing capacity, and smooth operation. Combined with the subsequent worm gear reducer, it forms a two-stage reduction system, which can significantly improve the final output torque, ensuring that even a small motor can generate sufficient shear force, while making the entire drive transmission system layout more centralized and efficient.

[0024] Furthermore, the input end of the worm gear is connected to the output end of the reducer via a spline connection, a flat square connection, or by integrally forming it with the output end of the reducer.

[0025] By adopting the above technical solutions, a variety of reliable and efficient torque transmission connection methods are provided. Spline connections can transmit larger torques and have good centering; flat square connections have a simple structure and are easy to assemble; one-piece molding completely eliminates connection gaps, improving transmission rigidity and accuracy. These methods can ensure smooth and lossless power transmission from the reducer to the worm gear, reducing vibration and noise caused by loose connections or errors.

[0026] Furthermore, it also includes a trigger switch, which has a first position and a second position in its travel stroke. When the trigger switch is in the first position, the driving member drives the moving blade to rotate toward the fixed blade; when the trigger switch is in the second position, the driving member drives the moving blade to rotate away from the fixed blade.

[0027] By adopting the above technical solution and setting a trigger switch with dual positions, bidirectional electric control of the scissor opening and closing action is achieved. Users can easily complete the entire cutting and resetting process by holding and pressing the trigger in different positions with one hand, without having to manually pry open the blade. This makes operation more labor-saving, convenient, and efficient, improving the automation of the product and the user experience.

[0028] In summary, this application has at least one of the following beneficial technical effects: 1. Through the synergy of multiple designs, including "worm gear axis offset," "L1>L2>L3 linkage optimization," and "connecting rod same-side motion constraint," a compact three-dimensional layout of the transmission system and a reduced product size are achieved while ensuring smooth and efficient transmission of force and motion. The worm gear pair provides a large reduction ratio and self-locking safety, while the optimized four-bar linkage realizes torque amplification and stroke conversion. Ultimately, the electric shears possess multiple advantages, including compact structure, powerful cutting force, smooth operation, and low noise.

[0029] 2. The unique dynamic transmission angle (pressure angle) design allows the mechanical efficiency of the mechanism to adaptively change according to load requirements during the shearing process (increasing at the final stage). This, combined with the optimized rod length ratio, significantly improves peak shear force output and energy utilization efficiency. Combined with a planetary gear reducer and a reliable connection method, a highly efficient, precise, and low-loss power transmission chain is constructed.

[0030] 3. By integrating a compact drive module (motor + planetary reducer), an offset worm gear transmission, and an eccentric linkage mechanism with controlled motion trajectory into a single design, the form factor of the portable tool is greatly optimized. Furthermore, convenient one-handed operation is achieved through electric bidirectional control (trigger switch). These features work together to solve the technical challenge of balancing portability, power, stability, and operability, providing a high-performance portable electric scissors solution. Attached Figure Description

[0031] 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 embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the structure of the electric scissors in this application; Figure 2 This is a cross-sectional structural diagram of the transmission mechanism. Figure 3 This is a cross-sectional structural diagram of an electric shears. Figure 4 This is a structural diagram of an electric scissors from another angle; Figure 5 This is an exploded view of the electric scissors. Figure 6 This is a schematic diagram of the parameter structure of electric scissors.

[0033] Reference numerals: 1. Drive component; 2. Worm gear; 3. Bracket; 31. Pivot axis; 32. Rotation axis; 4. Worm; 41. Worm axis; 5. Reducer; 51. Reduction gear set; 52. Gear ring; 6. Eccentric mechanism; 61. Eccentric wheel; 62. Connecting rod; 7. Moving tool; 8. Fixed tool; 9. Trigger switch. Detailed Implementation

[0034] 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.

[0035] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" 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 between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0036] In the description of this application, it should be understood that the terms "upper", "lower", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application 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 this application.

[0037] The technical solutions of this application will be described in detail below with reference to the accompanying drawings and specific embodiments. Unless otherwise specified, the features in the following embodiments can be combined with each other.

[0038] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the following description is provided in conjunction with the appendix. Figures 1 to 6 The specific embodiments of this utility model will be described in detail below.

[0039] This utility model discloses a portable electric scissors. Please refer to... Figure 1 , Figures 3 to 5 The electric scissors mainly include a bracket 3, a fixed blade 8 fixedly connected to the bracket 3, a movable blade 7 rotatably connected to the bracket 3 via a pivot axis 31, a drive unit 1 as a power source, a reducer 5 set on the output shaft of the drive unit 1, and a transmission mechanism that converts the rotational motion of the drive unit 1 into the reciprocating swing of the movable blade 7.

[0040] The transmission mechanism is the core component for achieving the purpose of this utility model. For example... Figures 2 to 5 As shown, the transmission mechanism specifically includes a worm 4, a worm wheel 2, an eccentric wheel 61, and a connecting rod 62. The worm 4 is rotatably supported on the bracket 3 via bearings and other structures. One end of the worm 4 is driven to the output end of the reducer 5 to receive power from the driving component 1 after reduction and torque amplification by the reducer 5. The reducer 5 is preferably a planetary gear reducer with a compact transmission structure and a large reduction ratio, which typically includes a reduction gear set 51 and a gear ring 52. In this embodiment, a three-stage planetary gear reducer is used. The connection method between the worm 4 and the output end of the reducer 5 can be varied, such as through spline fit, flat square fit, or the two can be directly integrally formed to ensure the reliability and efficiency of power transmission.

[0041] The worm gear 2 is rotatably mounted on the bracket 3 and meshes with the worm 4, thus enabling speed reduction and conversion of motion direction. For example... Figure 2 and Figure 3 As shown, the axis 41 of the worm gear 4 intersects perpendicularly in space with the pivot axis 31 of the moving blade 7, and these two intersecting axes together define a virtual "first plane". A key design feature of this invention is that the rotation axis 32 of the worm gear 2 is set parallel to the pivot axis 31 of the moving blade 7, and this rotation axis 32 is not located within the aforementioned first plane, but is offset by a predetermined distance relative to the first plane in a direction perpendicular to the plane. This offset design allows for more flexible spatial layout of the worm gear 2 and its related components, contributing to the compactness of the overall structure of the electric scissors.

[0042] Please see Figures 2 to 4 This invention limits the motion trajectory of the transmission mechanism to enhance operational stability. The moving blade 7 has a closed position close to the fixed blade 8 and an open position away from the fixed blade 8. Throughout the entire working stroke of the moving blade 7 rotating between the open and closed positions, the axis connecting the connecting rod 62 to the moving blade 7 and the axis connecting the connecting rod 62 to the eccentric wheel 61 are always located on the same side of the first plane defined by the worm gear axis 41 and the pivot axis 31. This directional arrangement ensures that the direction of the transmitted force remains consistent, helping to reduce vibration and unnecessary internal forces during mechanism operation.

[0043] To further enhance ease of operation, the electric scissors may also include a trigger switch 9. This trigger switch 9 has two triggerable positions along its travel: a first position and a second position. When the user presses the trigger switch 9 to the first position, it controls the drive element 1 to rotate in a first direction, thereby driving the moving blade 7 towards the fixed blade 8 to perform a cutting action. When the user presses the trigger switch 9 to the second position, it controls the drive element 1 to rotate in a second direction opposite to the first direction, thereby driving the moving blade 7 away from the fixed blade 8 to open the scissors. The trigger switch 9 has two identifiable position states along its travel. When the user slightly pulls the trigger to the first position (e.g., the half-stroke position), the trigger switch 9 generates a first electrical signal. After this signal is detected by the MCU, the MCU controls the drive element 1 (motor) to rotate in the first direction via the motor drive circuit, which in turn drives the moving blade 7 towards the fixed blade 8 through the entire transmission chain to perform a cutting action.

[0044] When the user pulls the trigger switch 9 to the second position, either deeper or fully depressed, the trigger switch 9 generates a second electrical signal different from the first electrical signal. Upon detecting this signal, the MCU controls the motor drive circuit to rotate the drive component 1 in the second direction, opposite to the first direction. This drives the moving blade 7 away from the fixed blade 8, achieving the opening and resetting of the blade. Alternatively, the trigger switch 9 can be designed with the initial position and the pressed position as the first and second positions, respectively. Pulling the trigger switch 9 to the second position performs cutting, and releasing the trigger switch 9 resets it to the first position to open. This design achieves electric opening and closing, making operation more effortless and convenient.

[0045] Please see Figures 2 to 5 The eccentric wheel 61 is coaxially and fixedly connected to the worm gear 2, and rotates together with the worm gear 2. One end of the connecting rod 62 is eccentrically connected to the eccentric wheel 61 at a position off its center of rotation via a pin, and the other end is eccentrically connected to the moving blade 7 at a position off its pivot axis 31 via a pin. In this way, the power of the drive component 1 is transmitted to the eccentric wheel 61 in sequence through the reducer 5, the worm 4, and the worm gear 2. The rotational motion of the eccentric wheel 61 is converted into the reciprocating oscillation of the moving blade 7 around its pivot axis 31 via the connecting rod 62, thereby realizing the coordinated shearing action with the fixed blade 8.

[0046] Please see Figure 6This invention further optimizes the dimensional relationships in the transmission mechanism to improve shearing performance. The distance between the rotating connecting axes at both ends of the connecting rod 62 is defined as L1 (i.e., the effective length of the connecting rod). The distance from the connecting axis of the moving blade 7 to the pivot axis 31 is defined as L2 (i.e., the lever arm length on the moving blade). The distance from the connecting axis of the eccentric wheel 61 to its own rotation axis 32 is defined as L3 (i.e., the eccentricity). This invention designs these dimensions to satisfy the following relationship: L1 is greater than L2, and L2 is greater than L3. This specific proportional relationship optimizes the force and torque transmission path, providing a larger effective torque when the moving blade 7 closes for shearing, making cutting more effortless and smoother.

[0047] From a dynamic transmission perspective, during the shearing process as the moving blade 7 rotates from the open position to the closed position, the angle α (which can be understood as the transmission pressure angle) formed by connecting the projection points of the connecting axes of the connecting rod 62 and the eccentric wheel 61, the connecting axis of the connecting rod 62 and the moving blade 7, and the pivot axis 31 of the moving blade 7 onto a plane perpendicular to the pivot axis 31 gradually decreases. This characteristic ensures that at the end of the cutting process, when the maximum material resistance needs to be overcome, the transmission mechanism is in a state of optimal force transmission efficiency, thereby improving the shearing capacity.

[0048] In summary, the portable electric scissors provided by this utility model embodiment, through the adoption of a transmission scheme combining a worm gear and an eccentric connecting rod, and through coordinated optimization of its spatial layout, size ratio, and motion trajectory, achieve the advantages of efficient and stable transmission, compact and small structure, and powerful and reliable cutting, effectively improving the overall performance of the product and the user experience.

[0049] This article uses specific examples to illustrate the principles and implementation methods of this utility model. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made to this utility model without departing from the principles of this utility model, and these improvements and modifications also fall within the protection scope of the claims of this utility model.

Claims

1. A portable electric scissors, comprising a bracket, a fixed blade fixedly connected to the bracket, a movable blade rotatably connected to the bracket via a pivot axis, and a drive component as a power source; characterized in that, It also includes a transmission mechanism, which comprises: The worm gear is rotatably connected to the bracket, and one end of it is driven to the output shaft of the drive component. The worm gear is rotatably connected to the support and meshes with the worm. An eccentric wheel, coaxially and fixedly connected to the worm gear; and The connecting rod is eccentrically connected at one end to the moving blade and eccentrically connected at the other end to the eccentric wheel. The worm's axis intersects the pivot axis perpendicularly to define a first plane, and the worm wheel's rotation axis is offset by a predetermined distance relative to the first plane.

2. The electric scissors according to claim 1, characterized in that, The rotation axis of the worm gear is offset by the preset distance in a direction parallel to the pivot axis.

3. The electric scissors according to claim 1, characterized in that, Let L1 be the distance between the axis connecting the connecting rod and the moving tool and the axis connecting the connecting rod and the eccentric wheel, and let L2 be the distance between the axis connecting the moving tool and the connecting rod and the pivot axis. Then the following relationship is satisfied: L1 > L2.

4. The electric scissors according to claim 3, characterized in that, Let L3 be the distance between the axis of rotation connecting the connecting rod and the eccentric wheel and the axis of rotation of the eccentric wheel. Then, the following relationship is further satisfied: L2 > L3.

5. The electric scissors according to claim 1, characterized in that, The moving blade has a closed position close to the fixed blade and an open position away from the fixed blade. The moving blade rotates between the closed position and the open position. During the rotation of the moving blade, the axis of rotation between the connecting rod and the moving blade is always located on the same side of the first plane.

6. The electric scissors according to claim 5, characterized in that, During the rotation of the moving blade, the axis connecting the connecting rod to the moving blade and the axis connecting the connecting rod to the eccentric wheel are both located on the same side of the first plane.

7. The electric scissors according to claim 5, characterized in that, As the moving blade rotates from the open position to the closed position, the included angle formed by connecting the projection points of the connecting axis between the connecting rod and the eccentric wheel, the connecting axis between the connecting rod and the moving blade, and the pivot axis on a plane perpendicular to the pivot axis gradually decreases.

8. The electric scissors according to claim 1, characterized in that, It also includes a speed reducer, the input end of which is driven to the output shaft of the drive unit, and its output end is driven to the worm gear. The speed reducer is a planetary gear reducer.

9. The electric scissors according to claim 8, characterized in that, The input end of the worm gear is connected to the output end of the reducer via a spline connection, a flat square connection, or by being integrally formed with the output end of the reducer.

10. The electric scissors according to claim 1, characterized in that, It also includes a trigger switch, which has a first position and a second position in its travel stroke. When the trigger switch is in the first position, the driving member drives the moving blade to rotate toward the fixed blade. When the trigger switch is in the second position, the driving member drives the moving blade to rotate away from the fixed blade.

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