Distance adjusting structure

Abstract

The invention discloses a distance adjusting structure, belongs to the field of gardening tools, solves the problem that an adjusting mechanism in the prior art is unreliable and needs frequent operation, and adopts the technical scheme that the distance adjusting structure comprises a machine body, a fixed cutter and a movable cutter, the fixed cutter and the movable cutter are arranged on the machine body, and the movable cutter and the fixed cutter are oppositely arranged to form a shearing gap; the fixed cutter can move relative to the movable cutter to adjust the size of a cutting gap, a distance adjusting transmission part is arranged on the machine body and driven by an external driving part, the machine body is provided with a rotatable distance adjusting part, the outer contour of the distance adjusting part is a non-circular curve, the distance adjusting part is in transmission connection with the worm gear, and the worm gear is in transmission connection with the fixed cutter. The distance adjusting transmission part is configured to limit rotation of the distance adjusting part when no power is input to the external driving part, and the outer contour of the distance adjusting part abuts against the fixed cutter so that the fixed cutter can be driven to be close to or away from the movable cutter when the distance adjusting part rotates. The reliability of the distance adjusting function is improved, and the shutdown distance adjusting frequency and time are reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of garden tools, in particular to a distance adjusting structure. BACKGROUND

[0002] In the existing branch chipper, the cutting gap between the fixed blade and the moving blade is usually adjusted by a screw bolt-nut mechanical adjusting mechanism. Specifically, by rotating the adjusting screw bolt, it is fed along the axial direction to push the fixed blade to swing around its rotation fulcrum, thereby changing the distance between the fixed blade and the moving blade. However, this structure has significant defects in actual operation: when the branch chipper is working, the cutter bears high-frequency impact load and severe vibration, while the working environment is dense in dust and variable in humidity. Under this working condition, the screw bolt-nut pair is prone to loosen, seize or slip, resulting in out-of-control cutting gap; more seriously, the threaded pair lacks reliable self-locking ability and may be self-retracted under the action of reverse impact force, causing the fixed blade to accidentally approach the moving blade and leading to cutter collision and even equipment damage. In order to maintain normal operation, the operator needs to frequently stop the machine for inspection and re-tighten or adjust the screw bolt, which not only reduces the continuous operation efficiency, but also increases the maintenance cost and operation complexity. Especially in long-time or high-intensity operation scenarios, this problem is particularly prominent, which seriously affects the user experience and equipment reliability. SUMMARY

[0003] The purpose of the present application is to provide a distance adjusting structure that solves the problem of unreliable adjusting mechanism in the prior art that requires frequent operation, improves the reliability of the distance adjusting function, and reduces the number and time of distance adjusting stop.

[0004] In order to achieve the above purpose, the present application adopts the following technical scheme: a distance adjusting structure, comprising a machine body, a fixed blade and a moving blade arranged on the machine body, the moving blade and the fixed blade are arranged opposite to each other to form a shearing gap, the fixed blade can move relative to the moving blade to adjust the size of the cutting gap, the machine body is provided with a distance adjusting transmission member, the distance adjusting transmission member is driven by an external driving member, the machine body is provided with a rotatable distance adjusting member, the outer contour of the distance adjusting member is a non-circular curve, the distance adjusting transmission member is in transmission connection, the distance adjusting transmission member is configured to limit the rotation of the distance adjusting member when the external driving member has no power input, the outer contour of the distance adjusting member abuts against the fixed blade, so that the fixed blade is driven to approach or move away from the moving blade when the distance adjusting member rotates.

[0005] After adopting the above technical solution, the present invention has the following advantages: The adjusting component adopts a non-circular curve outer contour design. The radius of curvature of each position on the non-circular curve outer contour of the adjusting component from its own rotation center is unidirectionally increasing or decreasing. Therefore, when the adjusting component rotates, the distance from the contact point between the adjusting component and the fixed blade to the rotation center of the adjusting component is also unidirectionally increasing or decreasing. This increase or decrease in distance is converted into the swing displacement of the fixed blade around the fulcrum, realizing the adjustment of the cutting gap. The movement form of the adjusting component matches the actual movement trajectory of the fixed blade, effectively reducing the occurrence of fixed blade jamming due to lateral force, thereby promoting the fixed blade to move more smoothly relative to the moving blade. At the same time, the adjusting transmission component forms a rotational constraint on the adjusting component in the absence of power, blocking the unexpected displacement caused by the continuous input of external power, and ensuring that the cutting gap is maintained stably during operation as much as possible. In addition, since the position locking function is built into the adjusting transmission component itself, there is no need to add an independent locking mechanism, and the overall structure of the machine is simplified.

[0006] Furthermore, one of the adjusting member and the body is provided with a limiting protrusion, and the other of the adjusting member and the body is provided with a limiting groove that cooperates with the limiting protrusion. The limiting groove extends along the rotation direction of the adjusting member and has a first end and a second end. The first end and the second end are used to limit the starting position and the ending position of the adjusting member, respectively.

[0007] By adopting the aforementioned technical solution, by setting mutually cooperating limiting protrusions and limiting grooves between the adjusting component and the machine body, the rotational movement of the adjusting component is constrained within a certain stroke range. When the limiting protrusions abut against the first end and the second end respectively, the adjusting component cannot continue to rotate in that direction, thus mechanically preventing the movement of the fixed blade and minimizing the risk of blade collision or excessively large ineffective cutting gap caused by over-adjustment.

[0008] Furthermore, the external drive component is connected to a power input shaft, the pitch-adjusting transmission component includes a meshing worm gear and a worm, the pitch-adjusting component is connected to the worm gear, and a clutch mechanism is provided between the power input shaft and the worm to enable or disengage the power input shaft and the worm.

[0009] Using the aforementioned technical solution, the worm gear transmission has a self-locking characteristic. When the external drive unit drives the worm to rotate, it can drive the worm wheel and the connected adjusting component to rotate synchronously. When the mechanism is subjected to impact or vibration loads, since the worm lead angle is less than the friction angle, the impact or vibration load cannot drive the worm to rotate in the opposite direction. From the transmission principle, this prevents the adjusting component from rotating on its own due to external forces, thus avoiding the problem of reduced work efficiency caused by frequent shutdowns for adjustment and tightening. This improves the reliability and stability of the equipment under high-frequency impact loads and harsh working environments. On the other hand, the worm gear structure has a speed reduction and torque amplification function, which can convert the high-speed, low-torque output of the drive unit into the low-speed, high-torque rotation of the adjusting component, making the rotation of the adjusting component more stable and precise, and achieving more refined adjustment of the cutting gap. When the cutting gap is adjusted to the correct position, the clutch mechanism automatically disengages, separating the power input shaft from the worm. At this time, the worm is completely disconnected from the external drive unit, cutting off the continuous input of external power and avoiding damage to parts such as the moving blade caused by excessive adjustment.

[0010] Furthermore, the clutch mechanism includes a first clutch block, a second clutch block, and an elastic element. The first clutch block is fixedly connected to the power input shaft, the second clutch block is connected to the worm gear transmission and can move axially relative to the first clutch block, and the elastic element acts on the second clutch block, so that the second clutch block has a tendency to maintain its movement toward the first clutch block and connect with the first clutch block.

[0011] Through the above technical solution, the elastic element continuously acts on the second clutch block, ensuring that the second clutch block always tends to move towards the first clutch block and remain connected. Under normal adjustment conditions, this achieves stable power transmission between the power input shaft and the worm gear, ensuring the continuity of power during the rotation of the adjusting component and the smoothness of the adjustment action. The elastic element also provides rebound space when the first and second clutch blocks disengage. When power needs to be cut off, the second clutch block is allowed to overcome the elastic force and slide axially to disengage, thus cutting off power between the power input shaft and the worm gear. The clutch action is achieved by mechanical force balance, requiring no electronic control or manual intervention.

[0012] Furthermore, the first clutch block and the second clutch block are provided with meshing teeth that can mesh with each other. The meshing teeth include a first inclined surface. The first inclined surface is located in the rotational direction in which the power input shaft drives the adjusting member to bring the fixed tool closer to the moving tool, and the second clutch block can slide axially along the first inclined surface to disengage.

[0013] By adopting the aforementioned technical solution, the driving force effectively transmits torque through the first inclined surface during the adjustment process of reducing the cutting gap. At the same time, if the driving force continues to be applied after the cutting gap is adjusted to the minimum, resulting in overload, the contact force acting on the first inclined surface will decompose into an axial component force, pushing the second clutch block to slide axially along the first inclined surface to disengage from engagement, thereby achieving overload cutting of power and avoiding hard collision between the fixed blade and the moving blade due to excessive adjustment as much as possible, thus forming overload protection from the mechanical structure level.

[0014] Furthermore, the meshing teeth also include a second inclined surface disposed opposite to the first inclined surface, wherein the angle α between the first inclined surface and the axis of rotation is greater than or equal to the angle β between the second inclined surface and the axis of rotation.

[0015] Through the above technical solution, the larger inclination angle of the first inclined surface makes it easier to generate sufficient axial force under overload, which makes it easier for the second clutch block to overcome the preload of the elastic element and slide off, thus achieving overload protection for the minimum cutting gap; while when the reverse rotation moves the fixed blade away from the moving blade, making it easier for the user to clean the debris on the moving blade or remove the fixed blade and the moving blade, the torque is transmitted by the second inclined surface. Its smaller inclination angle reduces the axial force generated under the same torque, making the engagement of the first clutch block and the second clutch block tighter, and preventing the phenomenon of slippage of the meshing teeth during power transmission as much as possible, ensuring that the adjustment action of moving the fixed blade away from the moving blade is more stable and reliable.

[0016] Furthermore, a first circumferential limiting structure is provided between the first clutch block and the power input shaft to restrict the circumferential rotation of the first clutch block relative to the power input shaft, and an axial limiting structure is provided to restrict the axial movement of the first clutch block relative to the power input shaft. A second circumferential limiting structure is provided between the second clutch block and the worm gear to restrict the circumferential rotation of the second clutch block relative to the worm gear.

[0017] The above technical solution ensures that the first clutch block is fixed in position during transmission, enabling reliable torque transmission between the power input shaft and the worm gear. Only the second clutch block undertakes the axial movement function, and the second clutch block can slide freely in the axial direction to achieve engagement or disengagement.

[0018] Furthermore, at least a portion of the outer contour of the adjusting member is an Archimedean spiral.

[0019] Through the above technical solution, the geometric characteristic of the Archimedes spiral is that its radial radius increases linearly with the change of rotation angle. When the adjusting component rotates synchronously with the worm gear, the part that abuts against the fixed blade will generate a uniform and continuous linear displacement, thereby driving the fixed blade to generate a continuous and uniform swing displacement around the fulcrum. This linear transmission characteristic allows the adjusting component to control the size of the cutting gap more intuitively and accurately, thus ensuring that the cutting gap is always at the minimum value when adjusting the gap.

[0020] Furthermore, the adjusting element and the worm gear are coaxially connected.

[0021] The above technical solution eliminates the intermediate transmission components, allowing both components to have the same center of rotation and synchronized angular displacement. This directly and seamlessly converts the rotation of the worm gear into the contour motion of the adjusting component, improving the response speed and accuracy of the cutting gap adjustment.

[0022] Furthermore, the external drive component includes a motor.

[0023] The above technical solution eliminates the need for manual wrenches or external force rotation during gap adjustment, achieving electrification and automation. The motor provides stable and controllable output torque, which, combined with the speed reduction and torque amplification characteristics of the worm gear, makes the gap adjustment process smooth, labor-saving, and responsive. It is especially suitable for frequent adjustments or high-load conditions. In addition, the electric drive minimizes the cutting gap errors or mechanical damage caused by uneven force during manual adjustment, improving operational consistency and equipment reliability. Attached Figure Description

[0024] The present invention will be further described below with reference to the accompanying drawings:

[0025] Figure 1 This is a schematic diagram of the adjusting structure of the present invention;

[0026] Figure 2 This is a partial structural schematic diagram of the adjustable distance structure of the present invention;

[0027] Figure 3 This is a schematic diagram of the adjusting element of the present invention;

[0028] Figure 4 This is a schematic diagram of another part of the adjustable distance structure of the present invention;

[0029] Figure 5 This is a partially exploded view of the adjustable distance structure of the present invention;

[0030] Figure 6 This is a schematic diagram of the structure of the first clutch component of the present invention;

[0031] Figure 7 This is a schematic diagram of the first clutch component of the present invention from another perspective;

[0032] Figure 8 This is a schematic diagram of the structure of the second clutch component of the present invention;

[0033] Figure 9 This is a schematic diagram of the second clutch component of the present invention from another perspective;

[0034] Figure 10 This is a schematic diagram of the adjusting member of the present invention rotating to the end position;

[0035] In the diagram, 10 is the machine body; 101 is the limiting protrusion; 102 is the connecting shaft; 11 is the fixed blade; 111 is the fixed blade rotation shaft; 12 is the moving blade; 13 is the cutting gap; 20 is the worm gear; 21 is the worm; 22 is the power input shaft; 23 is the first clutch block; 24 is the second clutch block; 25 is the elastic element; 26 is the meshing tooth; 261 is the first inclined surface; 262 is the second inclined surface; 27 is the spline; 28 is the spline groove; 29 is the shaft shoulder; 30 is the adjusting element; 301 is the outer contour; 302 is the limiting groove; 303 is the first end; 304 is the second end; and 31 is the snap ring. Detailed Implementation

[0036] 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.

[0037] The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein.

[0038] It should be understood that in the various embodiments of the present invention, the number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0039] It should be understood that in this invention, "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0040] It should be understood that in this invention, "multiple" refers to two or more. "And / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, X and / or Y can represent: X alone, X and Y simultaneously, or Y alone. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "Contains X, Y, and Z", "Contains X, Y, and Z" means that all three X, Y, and Z are contained; "Contains X, Y, or Z" means that one of X, Y, and Z is contained; "Contains X, Y, and / or Z" means that any one, two, or three of X, Y, and Z are contained.

[0041] The technical solution of the present invention will be described in detail below with reference to specific embodiments. The following specific embodiments may be combined or substituted with each other according to the actual situation, and the same or similar concepts or processes may not be described again in some embodiments.

[0042] like Figures 1 to 10 As shown, this invention provides an adjustable gap structure suitable for a wood chipper. The adjustable gap structure includes a body 10, a fixed blade 11 and a movable blade 12 mounted on the body 10. The movable blade 12 is positioned opposite the fixed blade 11 to form a cutting gap 13. The fixed blade 11 can move relative to the movable blade 12 to adjust the size of the cutting gap 13. The body 10 is provided with an adjustable gap transmission component, which is driven by an external drive component. The body 10 is provided with a rotatable adjustable gap component 30. The outer contour 301 of the adjustable gap component 30 is a non-circular curve. The adjustable gap component 30 is connected to a worm gear 20. The adjustable gap transmission component is configured to restrict the rotation of the adjustable gap component 30 when there is no power input from the external drive component, thereby preventing unexpected displacement caused by continuous input of external power and ensuring that the cutting gap 13 is maintained stably during operation. The outer contour 301 of the adjustable gap component 30 abuts against the fixed blade 11. Next, the radius of curvature of each position on the non-circular curved outer contour 301 of the adjusting member 30 from its own rotation center is unidirectionally increasing or decreasing. Therefore, when the adjusting member 30 rotates, the distance from the contact point between the adjusting member 30 and the fixed blade 11 to the rotation center of the adjusting member 30 is also unidirectionally increasing or decreasing. This increase or decrease in distance is converted into the swing displacement of the fixed blade 11 around the fulcrum. This motion form matches the actual motion trajectory of the fixed blade 11, effectively reducing the occurrence of the fixed blade 11 getting stuck due to the lateral component force. This pushes the fixed blade 11 to move more smoothly relative to the moving blade 12, so that the fixed blade 11 is driven to move closer to or away from the moving blade 12 when the adjusting member 30 rotates. This ensures that the cutting gap 13 is always at the minimum value during the adjustment, thus solving the problem that the cutting gap 13 becomes larger due to wear of the fixed blade 11 during operation.

[0043] Specifically, the pitch adjustment transmission component includes a meshing worm wheel 20 and a worm 21. The pitch adjustment component 30 is connected to the worm wheel 20, and the worm 21 is connected to the external drive component. Due to the self-locking characteristic of the worm wheel and worm gear transmission, when the external drive component drives the worm 21 to rotate, it can drive the worm wheel 20 and the pitch adjustment component 30 connected to it to rotate synchronously. When the mechanism is subjected to impact or vibration loads, since the lead angle of the worm 21 is less than the friction angle, the impact or vibration load cannot drive the worm 21 to rotate in the reverse direction. From the transmission principle, the possibility of the pitch adjustment component 30 rotating on its own due to external force is blocked, which avoids the problem of reduced work efficiency caused by frequent machine stops for adjustment and tightening as much as possible. This improves the reliability and stability of the equipment under high-frequency impact loads and harsh working environments. On the other hand, the worm wheel and worm gear structure has a speed reduction and torque increase function, which can convert the high-speed, low-torque output of the external drive component into the low-speed, high-torque rotation of the pitch adjustment component 30, making the rotation of the pitch adjustment component 30 more stable and precise, and realizing more precise adjustment of the cutting gap 13.

[0044] It should be noted that one end of the fixed blade 11 is rotatably mounted on the machine body 10 via the fixed blade rotation shaft 111. The adjusting member 30 can push the fixed blade 11 to rotate around the fixed blade rotation shaft 111 to approach the moving blade 12. Although this invention is described with a wood chipper as a typical application scenario, the principle and structure of its adjusting structure are not limited to this. It can also be widely applied to other mechanical equipment that requires adjustment of the cutting gap 13 between two opposing working parts, such as wood chippers, feed crushers, garden pruning machines, plastic crushers, and metal shearing equipment. In addition, although the fixed blade 11 adjusts the cutting gap 13 by swinging around a fulcrum in the above embodiment, in other embodiments, the fixed blade 11 can also be designed to move in a horizontal straight line. In this case, the rotational motion of the worm gear 20 can be converted into a linear thrust through a gear and rack mechanism or a cam push rod and other mechanical conversion devices, directly pushing the fixed blade 11 to translate and change the cutting gap 13 between it and the moving blade 12. This horizontal adjusting scheme can also combine the self-locking characteristics of the worm gear and the clutch protection mechanism to ensure the stability and safety of the adjustment process as much as possible. Adjustable element 30 can be a cam.

[0045] In this application, the body 10 is provided with a limiting protrusion 101, and the adjusting member 30 is provided with a limiting groove 302 that cooperates with the limiting protrusion 101. The limiting groove 302 extends circumferentially along the adjusting member 30 and has a first end 303 and a second end 304 opposite to each other. The limiting protrusion 101 is embedded in the limiting groove 302 and, by abutting against the first end 303 or the second end 304 of the limiting groove 302, constrains the rotational movement of the adjusting member 30 within a defined stroke range. After the initial assembly of the equipment is completed, the adjusting member 30 is located at the starting position of the adjustment stroke, at which time the limiting protrusion 101 abuts against the first end 303 of the limiting groove 302. The function of the first end 303 is to prevent the user from accidentally reversing the driving of the adjusting member 30 during the first use of the equipment, and to avoid abnormal interference between the non-circular outer contour 301 of the adjusting member 30 and the fixed blade 11 due to the adjusting member 30 rotating in a non-designed direction, i.e., reversing, thereby protecting the fixed blade 11 from mechanical damage. When the adjusting member 30 rotates to the end of its stroke in the adjustment direction, the limiting protrusion 101 abuts against the second end of the limiting groove 302, restricting the adjusting member 30 from continuing to rotate. This position corresponds to the maximum effective feed of the fixed blade 11, meaning that after the fixed blade 11 has worn down due to long-term use, the adjustment of the adjusting member 30 has compensated for it to the limit. If the rotation angle of the adjusting member 30 is not restricted, it may continue to rotate and exceed the effective adjustment range. Since the outer contour 301 of the adjusting member 30 is a non-circular curve, continued rotation will cause its contour to return to the initial position, resulting in the fixed blade 11 moving in the opposite direction and the cutting gap 13 suddenly increasing, making it impossible for the equipment to cut materials normally. Therefore, the second end 304 of the limiting groove 302 not only limits the upper limit of the adjusting stroke, but also prevents the adjusting member 30 from returning to the starting state due to excessive rotation, ensuring that the adjustment process is unidirectional and controllable; at the same time, this position indicates that the fixed blade 11 has reached its service life, reminding the user to replace the fixed blade 11 in time.

[0046] Because manual adjustment is prone to uneven force application, leading to errors in the cutting gap (13) or damage to the mechanism, an external drive component, including a motor, is used. This eliminates the need for manual wrenches or external force rotation, achieving electrification and automation of gap adjustment. The motor provides stable and controllable output torque, and combined with the reduction and torque-increasing characteristics of the worm gear structure, the gap adjustment process is smooth, labor-saving, and responsive, improving operational consistency and equipment reliability. It is especially suitable for frequent adjustments or high-load conditions.

[0047] To further improve the accuracy of the adjustment, the adjusting element 30 and the worm gear 20 are coaxially connected. The adjusting element 30 and the worm gear 20 are connected to the machine body 10 via the connecting shaft 102, eliminating the intermediate transmission components. This allows them to have the same rotation center and synchronous angular displacement, thereby directly and seamlessly converting the rotation of the worm gear 20 into the contour motion of the adjusting element 30, thus improving the response speed and accuracy of the cutting gap 13 adjustment.

[0048] Because the geometric characteristics of the Archimedean spiral are that its radial radius increases linearly with the change of rotation angle, and at least a part of the outer contour 301 of the adjusting member 30 is an Archimedean spiral, the radius of curvature of each position on the outer contour of the adjusting member 30 from its own rotation center is unidirectionally increasing or decreasing. Therefore, the adjustment of the cutting gap 13 is achieved by the continuous change of the radius of curvature when the adjusting member 30 rotates. When the adjusting member 30 rotates synchronously with the worm gear 20, the part that abuts against the fixed blade 11 will generate a uniform and continuous linear displacement, thereby pushing the fixed blade 11 to generate a continuous and uniform oscillating displacement around the fulcrum. This linear transmission characteristic allows the adjusting member 30 to control the size of the cutting gap 13 more intuitively and accurately, ensuring that the cutting gap 13 is always at its minimum value during adjustment, and better solving the problem that the cutting gap 13 increases due to wear of the fixed blade 11 during operation.

[0049] Furthermore, the external drive unit is connected to a power input shaft 22, and a clutch mechanism is provided between the power input shaft 22 and the worm gear 21 to connect or disconnect the power between them. When the clearance is adjusted to the correct position, the clutch mechanism automatically disengages, separating the power input shaft 22 from the worm gear 21. At this time, the worm gear 21 is completely disconnected from the external drive unit, cutting off the continuous input of external power and minimizing damage to parts such as the moving tool 12 caused by excessive clearance adjustment.

[0050] Specifically, the clutch mechanism includes a first clutch block 23, a second clutch block 24, and an elastic element 25. The first clutch block 23 is fixedly connected to the power input shaft 22, and the second clutch block 24 is drivenly connected to the worm gear 21 and can move axially relative to the first clutch block 23. The elastic element 25 acts on the second clutch block 24, causing the second clutch block 24 to tend to move towards the first clutch block 23 and connect with it. Under normal adjustment conditions, it can achieve stable power transmission between the power input shaft 22 and the worm gear 21, ensuring the continuity of power and the smoothness of the adjustment action when the adjusting member 30 rotates. The elastic element also provides a rebound space when the first clutch block 23 and the second clutch block 24 disengage. When it is necessary to cut off the power, the second clutch block 24 is allowed to overcome the elastic force and slide axially to disengage, thereby cutting off the power between the power input shaft 22 and the worm gear 21. The clutch action is achieved by mechanical force balance, without electronic control or manual intervention. The elastic element 25 can be a spring.

[0051] The first clutch block 23 and the second clutch block 24 are provided with meshing teeth 26 that can mesh with each other. The meshing teeth 26 include a first inclined surface 261. The first inclined surface 261 is located in the rotation direction of the power input shaft 22 driving the adjusting member 30 to bring the fixed blade 11 closer to the moving blade 12. The second clutch block 24 can slide and disengage along the first inclined surface 261, so that during the adjustment process of reducing the cutting gap 13, the driving force can effectively transmit torque through the first inclined surface 261. At the same time, if the driving force is continued to be applied after the adjustment is to the minimum cutting gap 13, resulting in overload, the contact force acting on the first inclined surface 261 will be decomposed into an axial component force, pushing the second clutch block 24 to slide and disengage along the first inclined surface 261, thereby realizing the overload cut-off of the power and avoiding hard collision between the fixed blade 11 and the moving blade 12 due to over-adjustment as much as possible, thus forming overload protection from the mechanical structure level.

[0052] Furthermore, the meshing teeth 26 also include a second inclined surface 262 disposed opposite to the first inclined surface 261. The angle α between the first inclined surface 261 and the axis of rotation is greater than or equal to the angle β between the second inclined surface 262 and the axis of rotation. Preferably, the angle α is greater than the angle β. The larger inclination angle of the first inclined surface 261 makes it easier to generate sufficient axial force under overload, causing the second clutch block 24 to more easily overcome the preload force of the elastic element 25 and slip out, thus achieving overload protection for the minimum clearance. When the reverse rotation moves the fixed blade 11 away from the moving blade 12, making it easier for the user to clean the debris on the moving blade 12 or remove the fixed blade 11 and the moving blade 12, the torque is transmitted by the second inclined surface 262. Its smaller inclination angle reduces the axial force generated under the same torque, making the meshing of the first clutch block 23 and the second clutch block 24 tighter, and preventing the meshing teeth 26 from slipping during power transmission as much as possible, ensuring that the adjustment action of the fixed blade 11 moving away from the moving blade 12 is more stable and reliable. When the angle β between the second inclined plane 262 and the axis of rotation approaches 0°, its surface tends to be parallel to the axial direction. At this time, the contact force is almost entirely used for circumferential force transmission, and almost no component force is generated to cause the second clutch block 24 to slide axially. Therefore, the two clutch blocks can maintain stable engagement during the reverse rotation without accidental disengagement, so that the adjusting piece 30 can smoothly reverse and exit, ensuring that the adjustment action of the fixed tool 11 away from the moving tool 12 is smooth, continuous and reliable.

[0053] Furthermore, a first circumferential limiting structure is provided between the first clutch block 23 and the power input shaft 22 to restrict the circumferential rotation of the first clutch block 23 relative to the power input shaft 22, and an axial limiting structure is provided to restrict the axial movement of the first clutch block 23 relative to the power input shaft 22. A second circumferential limiting structure is provided between the second clutch block 24 and the worm gear 21 to restrict the circumferential rotation of the second clutch block 24 relative to the worm gear 21. This ensures that the first clutch block 23 is fixed in position during transmission, so that the power input shaft 22 and the worm gear 21 can reliably transmit torque. Only the second clutch block 24 undertakes the axial movement function. The second clutch block 24 can slide freely in the axial direction to achieve the engagement or disengagement action.

[0054] The first and second circumferential limiting structures are the spline 27 on the power input shaft 22 and the worm gear 21, respectively, and the spline groove 28 on the first clutch block 23 and the second clutch block 24, which mate with the spline 27. This allows the first clutch block 23 and the second clutch block 24 to reliably transmit torque to the power input shaft 22 and the worm gear 21 through the spline groove 28. Furthermore, the spline 27 and the spline groove 28 are detachably connected, facilitating assembly, maintenance, and replacement of parts. Finally, the axial limiting structure includes a shoulder 29 integrally formed with the power input shaft 22 and a retaining ring 31 detachably mounted on the power input shaft 22. The lower end face of the shoulder 29 abuts against the upper end face of the first clutch block 23, restricting the first clutch block 23 from moving upward axially. The retaining ring 31 is embedded in an annular groove on the power input shaft 22 and abuts against the lower end face of the first clutch block 23, restricting the first clutch block 23 from moving downward axially. Thus, the first clutch block 23 is reliably positioned axially, rotating only synchronously with the power input shaft 22, and cannot move axially. Of course, in other embodiments, the axial limiting structure can also take other forms. For example, a threaded section can be provided at the end of the power input shaft 22, and the first clutch block 23 can be pressed by a lock nut to achieve bidirectional limiting; or, a limiting rib can be provided on the power input shaft 22, and the inner hole of the first clutch block 23 can be provided with an axial stepped surface that mates with it, and the axial movement is limited by the contact between the limiting rib and the stepped surface.

[0055] In use, with the clutch mechanism engaged, the external drive unit drives the power input shaft 22 to rotate forward. The power input shaft 22 drives the worm gear 21 to rotate synchronously via the clutch mechanism. At this time, the first inclined surface 261 of the first clutch block 23 and the first inclined surface 261 of the second clutch block 24 are in contact with each other and transmit torque, causing the worm gear 21 to rotate accordingly. The worm gear 21 drives the worm wheel 20, which meshes with it, to rotate. The worm wheel 20 is coaxially connected with the adjusting member 30, so the adjusting member 30 rotates synchronously forward with the worm wheel 20. The non-circular outer contour of the adjusting member 30 abuts against the fixed blade 11. During rotation, it pushes the fixed blade 11 to swing around the fixed blade rotation axis 111, causing the cutting gap 13 between the fixed blade 11 and the moving blade 12 to gradually decrease and eventually be maintained at the minimum set value, thereby compensating for the increase in the cutting gap 13 caused by the wear of the fixed blade 11 due to long-term use. Before the fixed blade 11 contacts the moving blade 12, the resistance that the adjusting member 30 needs to overcome to push the fixed blade 11 is relatively small, denoted as the first load. After the fixed blade 11 contacts the moving blade 12, the adjusting member 30 needs to further press the two blades together to maintain the minimum gap. At this time, the reaction force increases significantly, denoted as the second load, which is greater than the first load. This reaction force is transmitted in the opposite direction to the clutch mechanism via the adjusting member 30, worm gear 20, and worm 21, acting on the inclined contact pair of the first clutch block 23 and the second clutch block 24. Since the first inclined surface 261 has an inclination angle, the reverse load will decompose into an axial component force on the inclined surface. This axial component force pushes the second clutch block 24 to move axially along the power input shaft 22, compressing the elastic member 25. When the axial component force is greater than the preload of the elastic member 25, the second clutch block 24 is displaced, causing the first clutch block 23 and the second clutch block 24 to disengage, the power transmission path is cut off, and the adjusting process is automatically terminated.

[0056] When the external drive unit drives the power input shaft 22 to rotate in the opposite direction, the second inclined surface 262 of the first clutch block 23 and the second inclined surface 262 of the second clutch block 24 engage, driving the worm gear 21 to rotate. The worm gear 21 drives the worm wheel 20 to rotate, and the rotation of the worm wheel 20 synchronously drives the cam to rotate in the opposite direction, so that the fixed blade 11 moves away from the moving blade 12, making it easier for the user to clean the debris on the moving blade 12 or remove the fixed blade 11 and the moving blade 12.

[0057] In addition to the preferred embodiments described above, the present invention has other embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection claimed by the present invention.

Claims

1. A variable gap structure comprising a housing (10), a stationary blade (11) and a movable blade (12) disposed on said housing (10), said movable blade (12) being disposed opposite said stationary blade (11) to form a cutting gap (13), said stationary blade (11) being movable relative to said movable blade (12) to adjust the size of the cutting gap (13), characterized in that, The machine body (10) is provided with a pitch adjusting transmission member driven by an external driving member, the machine body (10) is provided with a rotatable pitch adjusting member (30), the outer contour (301) of the pitch adjusting member (30) is a non-circular curve, the pitch adjusting member (30) is in transmission connection with the pitch adjusting transmission member, the pitch adjusting transmission member is configured to limit the rotation of the pitch adjusting member (30) when the external driving member has no power input, the outer contour (301) of the pitch adjusting member (30) abuts against the fixed knife (11) to drive the fixed knife (11) to move close to or away from the moving knife (12) when the pitch adjusting member (30) rotates. ​ 2. The pitch structure of claim 1, wherein, One of the pitch adjusting member (30) and the machine body (10) is provided with a limiting protrusion (101), and the other of the pitch adjusting member (30) and the machine body (10) is provided with a limiting groove (302) matched with the limiting protrusion (101), the limiting groove (302) is arranged along the rotation direction of the pitch adjusting member (30) and has a first end portion (303) and a second end portion (304), the first end portion (303) and the second end portion (304) are used to limit the start position and the end position of the pitch adjusting member (30) respectively.

3. The pitch structure according to claim 1 or 2, characterized in that The external driving member is connected with a power input shaft (22), the pitch adjusting transmission member includes a worm wheel (20) and a worm (21) in meshing connection with each other, the pitch adjusting member (30) is in transmission connection with the worm wheel (20), and a clutch mechanism for connecting or disconnecting the power between the power input shaft (22) and the worm (21) is arranged between the power input shaft (22) and the worm (21).

4. The pitch structure of claim 3, wherein, The clutch mechanism includes a first clutch block (23), a second clutch block (24) and an elastic member (25), the first clutch block (23) is fixedly connected with the power input shaft (22), the second clutch block (24) is in transmission connection with the worm (21) and can move axially relative to the first clutch block (23), and the elastic member (25) acts on the second clutch block (24) to make the second clutch block (24) have a tendency to move towards the first clutch block (23) to be connected with the first clutch block (23).

5. The pitch structure of claim 4, wherein, The first clutch block (23) and the second clutch block (24) are provided with meshing teeth (26) which can mesh with each other, the meshing teeth (26) include a first inclined surface (261), the first inclined surface (261) is located in the rotation direction of the power input shaft (22) for driving the pitch adjusting member (30) to move the fixed knife (11) close to the moving knife (12), and the second clutch block (24) can axially slide away along the first inclined surface (261).

6. The pitch structure of claim 5, wherein, The meshing teeth (26) further include a second inclined surface (262) arranged opposite to the first inclined surface (261), and the included angle α between the first inclined surface (261) and the rotation axis is greater than or equal to the included angle β between the second inclined surface (262) and the rotation axis.

7. The pitch structure of claim 4, wherein, The first clutch block (23) and the power input shaft (22) are provided with a first circumferential limiting structure for limiting the circumferential rotation of the first clutch block (23) relative to the power input shaft (22), and an axial limiting structure for limiting the axial movement of the first clutch block (23) relative to the power input shaft (22), and the second clutch block (24) and the worm (21) are provided with a second circumferential limiting structure for limiting the circumferential rotation of the second clutch block (24) relative to the worm (21).

8. The pitch structure of claim 1, wherein, At least a part of the outer contour (301) of the distance adjusting piece (30) is an Archimedes spiral.

9. The pitch structure of claim 3, wherein, The distance adjusting piece (30) and the worm wheel (20) are coaxially connected.

10. The pitch structure of claim 1, wherein, The external driving piece comprises a motor.

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