Safety shaft and torque transmission method with limited space

Abstract

The application discloses a safety shaft suitable for limited space and a torque transmission and overload protection method, which comprises a driven section, a pre-tightening spring is fixedly sleeved outside the driven section, one end of the pre-tightening spring abuts against a cylindrical disengaging section which is movably sleeved outside the driven section through a ball track moving pair, the end of the disengaging section away from the pre-tightening spring is engaged with a cylindrical driving section which is rotatably sleeved outside the driven section through end face teeth, and a locking mechanism is arranged in the end of the disengaging section close to the pre-tightening spring and connected to the side wall of the driven section. The application integrates the overload protection mechanism and the transmission shaft body, directly integrates the torque limiting function into the structure of the shaft, realizes the integration of the overload protection function and the shaft transmission function, and improves the compactness, torsional stiffness and bearing strength of the transmission system.

Description

Technical Field

[0001] This invention belongs to the field of mechanical transmission and overload protection technology, specifically relating to a torque-adjustable safety shaft suitable for reuse in environments with limited installation space. This invention also relates to a torque transmission method for such a reusable torque-adjustable safety shaft. Furthermore, this invention relates to an overload protection method for the same type of shaft. Background Technology

[0002] The stability and reliability of mechanical transmission systems are core factors determining the overall performance and life-cycle cost of equipment. In modern industry, from automated production lines and precision CNC machine tools to multi-degree-of-freedom industrial robots, the drive shaft, as a crucial bridge connecting the power source and the actuator, plays an indispensable role in the power transmission chain. However, in actual working conditions, unforeseen factors such as workpiece jamming, operational errors, or sudden load changes often cause the transmission chain to experience instantaneous impact torque far exceeding normal levels. Without effective overload suppression measures, such impacts will be rapidly transmitted to core components such as motors and reducers, potentially triggering equipment shutdowns and disrupting production rhythms, or even causing transmission component breakage or safety accidents, resulting in significant economic losses.

[0003] Machining a circular groove on the shaft is a simplified safety shaft design. The principle is to create an artificial stress concentration zone through geometric weakening. A circular groove of a specific radius and depth is created at the journal to construct a pre-designed weak section. When the transmitted torque exceeds the design limit, the shear stress at this section exceeds the material strength, causing the shaft to fracture at this point, thus cutting off power transmission and protecting downstream equipment. However, this design has shortcomings: the machining accuracy of the circular groove directly affects the accuracy of the fracture threshold, and fatigue loads under actual working conditions can easily lead to premature fracture or threshold drift; secondly, the shaft with the circular groove is a disposable part, and once it breaks, the entire shaft must be replaced, resulting in high maintenance costs and long downtime; furthermore, since fracture failure is a destructive form, rapid shaft replacement is not possible, making geometric weakening of the shaft unsuitable for applications requiring frequent overload protection or high continuous operation efficiency.

[0004] A torque limiter is a specially designed overload protection device that can quickly cut off power transmission and isolate the overload source when the torque exceeds a preset threshold, thereby protecting downstream equipment from damage. Its key advantage is that it can quickly restore transmission function after fault diagnosis, making it a crucial component for ensuring the safe operation of the transmission system and minimizing downtime.

[0005] Common torque limiters on the market are mainly divided into three categories: friction type, ball type, and shear pin type. They achieve overload protection function with different working principles and show significant differences in performance characteristics and application scenarios.

[0006] Friction-type torque limiters are currently the most widely used, simplest in structure, and most economical type. Their working principle involves using a spring to press a friction plate assembly, transmitting the rated torque through static friction between the driving and driven plates. When an overload occurs, the actual torque exceeds the preset friction limit, causing relative slippage between the friction plates, thus limiting the torque increase and protecting downstream equipment. The core advantages of this type of product are its simple structure, low cost, and the ability for users to steplessly adjust the torque setting by adjusting the spring pressure, offering high flexibility. Furthermore, the equipment usually automatically resumes transmission function after the overload is eliminated, requiring no manual intervention. However, it still has certain limitations in its design: the torque control accuracy is relatively low, with an error range typically around ±10%, making it difficult to meet the requirements of extremely precise protection thresholds; the slippage process is essentially a conversion of mechanical energy into heat energy, and continuous or frequent overloads can cause a sharp increase in the friction interface temperature, leading to thermal degradation of the friction material and a decrease in protective performance; wear of the friction plates is inevitable, requiring regular maintenance and replacement, increasing the total life-cycle cost; residual torque is still transmitted in the slippage state, and it cannot directly output electrical signals for automated shutdown control.

[0007] Ball-type torque limiters represent a higher precision and faster response technology. They incorporate a precision ball or roller mechanism. During normal operation, a strong spring presses the rolling elements into specially contoured grooves on the driving and driven discs, transmitting torque through the compression between the rolling elements and the groove sidewalls. In the event of an overload, the axial force acting on the rolling elements instantly overcomes the spring resistance, causing the rolling elements to quickly disengage from the grooves, resulting in complete separation of the driving and driven parts and instantaneous power cut-off. This design offers significant advantages: the separation action is sensitive and rapid, with a response time down to the millisecond level; the torque setting accuracy is high, typically ±3% to 5%, meeting the protection requirements of precision transmissions; due to rigid meshing, backlash-free transmission is achieved, and the displacement of the rolling elements during an overload can trigger a limit switch to output an electrical signal for equipment alarms or emergency shutdowns. However, this advantage comes at a significant cost: the complex structure and high precision requirements for processing and assembly result in a relatively high price; in addition, depending on the reset method, some models cannot automatically reset after being disengaged due to overload, requiring manual reversal or the use of special tools to re-engage, making them less convenient to operate than friction type.

[0008] The shear pin torque limiter is a classic form of overload protection. Its principle is as follows: a precisely calculated weak point is artificially placed in the transmission path. During normal operation, torque is transmitted entirely through the pin. Once an overload occurs, the shear stress on the pin exceeds its ultimate strength, causing it to break immediately and interrupting power transmission, acting as a "mechanical fuse." The advantages of this type of device are its simple structure, low cost, and the ability to precisely control the protection threshold through pin size and material. It is still used in some low-speed, infrequently overloaded equipment in heavy industry. However, its inherent limitations constitute a significant constraint: each overload protection action comes at the cost of permanent pin damage; the pin is a single-use component, requiring machine shutdown and replacement after each action, leading to prolonged production interruptions and cumbersome replacement procedures; and the metal shavings generated when the pin breaks can contaminate the internal environment of the equipment, posing a wear risk to gears, bearings, and other parts. Therefore, the shear pin torque limiter has been gradually replaced by friction or ball bearing types in modern automated equipment.

[0009] In summary, while the three types of torque limiters play important protective roles in their respective suitable application scenarios, from the perspective of the overall design of mechanical transmission systems, they generally follow an "external" or "modular" integration mode. That is, they are connected in series between the drive shaft and the load shaft as independent, fully functional components via keys, couplings, flanges, and other connecting parts. Although this design paradigm is relatively straightforward in terms of functional implementation, it introduces several irreconcilable structural contradictions and performance bottlenecks at the system level. When dealing with sudden overloads, their core components will suffer irreversible damage or performance degradation. Therefore, there is a significant dilemma in the current field of mechanical transmission: traditional safety couplings, whether shear-type, friction-type, or ball-type, generally adopt an independent, separate design, connected in series in the transmission chain as individual components. This not only disrupts the structural continuity of the shaft system, leading to a decrease in overall stiffness and insufficient torsional stiffness, but also results in significant volume redundancy and installation space requirements. This discrete integration model necessitates the inclusion of large, independent modules within a limited space, increasing manufacturing costs and limiting its applicability under extreme conditions. Currently, in applications with limited installation space, such as the rocker arm of a coal mining machine, the drive shaft of the rocker arm motor (usually an internal motor) not only bears significant loads but also frequently experiences unpredictable impact loads, resulting in complex operating conditions. Furthermore, due to the limited internal space of the motor, the shaft's installation layout is extremely compact: the axial installation length is constrained by the rocker arm housing structure, and the radial dimension is limited by the mere 1-2 mm gap between the motor's inner bore and the shaft, making it difficult to arrange commonly used shear pin-type safety shafts.

[0010] To address this critical issue, this invention proposes a novel safety shaft design that abandons the traditional disposable concept. Its core mechanism lies in its ability to precisely disengage and completely cut off power transmission when an overload occurs, ensuring that expensive front-end equipment such as motors and reducers are protected from damage. This provides an innovative solution for mechanical equipment that balances reliable protection with cost-effectiveness. Summary of the Invention

[0011] The purpose of this invention is to provide a torque-adjustable safety shaft that is suitable for installation in limited space and can be reused, thus solving the problems of limited space and easy weakening of shaft strength in existing series structures.

[0012] Another object of the present invention is to provide a torque transmission method for a torque-adjustable safety shaft that is suitable for installation in space-constrained applications and can be reused.

[0013] Another object of the present invention is to provide an overload protection method for a reusable torque-adjustable safety shaft applicable to installation spaces with limited space.

[0014] The first technical solution adopted in this invention is: a torque-adjustable safety shaft applicable to installation space with limited capacity and reusable, including a driven section, a preload spring fixedly sleeved on the driven section, one end of the preload spring abutting against a cylindrical release section sleeved on the driven section via a ball track moving pair, the end of the release section away from the preload spring engaging with a cylindrical driving section rotatably sleeved on the driven section via end face teeth, and a locking mechanism connected to the side wall of the driven section is provided radially inside the end of the release section near the preload spring.

[0015] The first technical solution of this invention is further characterized in that, The driven section is located at the end of the preload spring away from the release section, which is inwardly contracted to form a shoulder. The preload spring, the release section, and the driving section are all located in the small diameter section of the driven section. A large round nut is threadedly connected to the small diameter section of the driven section near the shoulder. The end of the preload spring away from the release section abuts against the large round nut.

[0016] The screw-in distance of the large round nut compressing the preload spring L Represented as:

[0017] In the formula, T The preset overload torque is used as the basis for adjusting the screw-in distance of the large round nut according to the actual torque requirements during engineering. L ; K This is the torque coefficient of the preload spring. d The nominal diameter of the large round nut. k This is the spring constant of the preload spring.

[0018] The ball track moving pair includes a cylindrical positioning frame. Multiple sets of positioning holes are evenly spaced along the circumference on the side wall of the positioning frame. Each set of positioning holes includes multiple positioning holes evenly spaced along the axial direction of the positioning frame. Elongated arc grooves are provided on the inner wall of the disengaging section and the side wall of the driven section corresponding to each set of positioning holes. Each positioning hole contains a ball with both ends extending outward and conforming to the arc grooves on the disengaging section and the driven section.

[0019] The end face teeth are respectively opened at the ends of the disengagement section and the driving section that are close to each other. The teeth of the upper end face teeth of the disengagement section and the teeth of the upper end face teeth of the driving section are both conical and interlocked.

[0020] Pressure angle of the end face teeth The following requirements must be met:

[0021] In the formula, m is the end face tooth module, and z is the number of end face teeth. K d is the torque coefficient of the preload spring, and d is the diameter of the driven section where the preload spring is located.

[0022] The locking mechanism includes multiple T-shaped limiting grooves evenly spaced along the circumference on the inner wall of the release section. Each limiting groove is arranged radially narrowing along the release section. A T-shaped locking wedge with its bottom end protruding outward is slidably fitted inside the limiting groove. A compression spring is connected between the top of the locking wedge and the bottom of the limiting groove. A locking groove adapted to the size of each locking wedge is provided on the side wall of the driven section corresponding to the bottom end of the driven wedge.

[0023] A blind mounting hole is provided along the axial direction at the end of the driven section near the driving section. A pull-off shaft with one end extending outward is coaxially connected to the blind mounting hole via a bearing.

[0024] The second technical solution adopted in this invention is: a torque transmission method for a reusable torque-adjustable safety shaft with limited installation space. During operation, power is input from the driving section, transmitted to the disengagement section through the end face teeth, and then transmitted to the driven section through the ball track moving pair between the disengagement section and the driven section, thereby realizing torque transmission.

[0025] The third technical solution adopted in this invention is: an overload protection method for a reusable torque-adjustable safety shaft with limited installation space. When overloaded, the driven section is blocked and stops rotating. The driving section pushes the disengagement section to move axially and disengage through the end face teeth. Then, the locking wedge in the locking mechanism moves axially to the top of the locking groove and falls into the locking groove under the extension of the compression spring and engages with it, locking the disengagement section in the disengagement position. The power transmission of the driving section is cut off to achieve overload protection.

[0026] The beneficial effects of this invention are as follows: This invention is applicable to space-constrained safety shafts and torque transmission and overload protection methods. By integrating the overload protection mechanism with the transmission shaft body, the torque limiting function is directly incorporated into the shaft structure. When the system is overloaded, the torque can be quickly cut off, and in the disengaged state, it relies on its own structure to stably lock and prevent unnecessary collision damage. This achieves the integration of overload protection and shaft transmission functions, improving the structural compactness, torsional stiffness, and load-bearing capacity of the transmission system. It effectively avoids the shortcomings caused by the disruption of shaft structure continuity by external independent modules, such as reduced stiffness, shortened fatigue life, and additional installation space requirements. It is suitable for heavy-load working conditions such as coal mining machine rocker arms where installation space is extremely limited. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall structure of the torque-adjustable safety shaft applicable to installation spaces with limited space, which is a reusable type of shaft according to the present invention. Figure 2 This is an axial cross-sectional view of the torque-adjustable safety shaft applicable to the present invention, which has limited installation space and can be reused. Figure 3 This is a schematic diagram of the driven section in a reusable torque-adjustable safety shaft applicable to installation space, according to the present invention. Figure 4 This is a schematic diagram of the positioning frame in a reusable torque-adjustable safety shaft applicable to installation space, according to the present invention. Figure 5 This is a schematic diagram of the disengagement section in a reusable torque-adjustable safety shaft applicable to installation spaces, as described in this invention. Figure 6 This is a partial cross-sectional schematic diagram of the disengagement section in a reusable torque-adjustable safety shaft with limited installation space, to which the present invention is applicable. Figure 7 yes Figure 6 This invention relates to a partially enlarged schematic diagram of a reusable torque-adjustable safety shaft applicable to installation spaces. Figure 8 This is a schematic diagram of the structure of the reusable torque-adjustable safety shaft with limited installation space, applicable to the present invention, where the additional section can be detached. Figure 9 This is a schematic diagram illustrating an application scenario for the invention, specifically a reusable torque-adjustable safety shaft with limited installation space.

[0028] In the diagram, 1. Driven section, 2. Preload spring, 3. Disengagement section, 4. End face tooth, 5. Driven section, 6. Shoulder, 7. Large round nut, 8. Positioning bracket, 9. Arc groove, 10. Ball bearing, 11. Limiting groove, 12. Locking wedge, 13. Compression spring, 14. Locking groove, 15. Mounting blind hole, 16. Bearing, 17. Pull-off shaft, 18. Large stop washer, 19. Small round nut, 20. Small stop washer; 31. Detach from the main body of the segment; 32. Detach from the additional segment. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0030] Example 1 This invention provides a reusable torque-adjustable safety shaft suitable for installations with limited space, such as... Figure 1 and Figure 2 As shown, it includes a driven section 1, a preload spring 2 fixedly sleeved on the driven section 1, one end of the preload spring 2 abutting against a cylindrical release section 3 sleeved on the driven section 1 via a ball track moving pair, the end of the release section 3 away from the preload spring 2 engaging with a cylindrical driving section 5 rotatably sleeved on the driven section 1 via end face teeth 4, the end of the release section 3 near the preload spring 2 is radially provided with a locking mechanism connected to the side wall of the driven section 1, the end of the driven section 1 near the driving section 5 is axially provided with a blind hole 15, a pull-off shaft 17 extending outward is coaxially rotatably connected in the blind hole 15 via a bearing 16.

[0031] like Figure 3 As shown, the driven section 1, located at the end of the preload spring 2 furthest from the disengagement section 3, contracts inward to form a shoulder 6. The preload spring 2, disengagement section 3, and driving section 5 are all located in the small-diameter section of the driven section 1, making the outer diameter dimensions of different sections of the safety shaft approximately the same. External gear sleeves are fitted on the large-diameter sections of both the driving section 5 and the driven section 1 for power input and output, thus achieving an integrated design. A large round nut 7 is threadedly connected to the small-diameter section of the driven section 1 near the shoulder 6. The end of the preload spring 2 furthest from the disengagement section 3 abuts against the large round nut 7, which limits its movement, thereby applying an axial preload force towards the driving section 5 to the disengagement section 3. The threaded section has a groove for engaging the inner tongue of the large stop washer 18. The large stop washer 18 is installed on one end of the large round nut 7. After tightening the large round nut 7 to a sufficient preload force, the outer tongue of the large stop washer 18 is bent to achieve locking. The preload force provided by the large round nut 7 is adjusted by adjusting the screw-in distance of the large round nut 7. Let the screw-in distance be L, the overload protection torque be T, the nominal diameter of the large round nut 7 be d (i.e., the diameter of the driven section 1 shaft is d), the torque coefficient of the preload spring 2 be K, and the elastic coefficient be k. Then the pressure on the preload spring 2 can be expressed by the formula... Calculations show that the screw-in distance L of the large round nut 7 can be obtained by substituting the pressure F into Hooke's Law ( It is derived that, i.e. The large round nut 7 can be adjusted to the required preload position by calculating the screw-in distance using this formula. In engineering, the preload of the preload spring 2 can be changed by adjusting the screw-in distance of the large round nut 7. The preload force of the preload spring 2 directly determines the limit torque that the safety shaft can withstand, thereby obtaining the expected overload protection torque.

[0032] The active section 5, away from the disengagement section 3, is provided with a small round nut 19 that is threadedly connected to the small diameter section of the driven section 1. The threaded section has a groove for accommodating the inner tongue of the small stop washer 20. The small stop washer 20 is installed on one end of the small round nut 19. After the active section 5 is axially positioned away from the load by the small round nut 19, the outer tongue of the small stop washer 20 is bent to abut against the cut of the small round nut 19, thereby achieving locking and preventing loosening.

[0033] like Figures 4 to 7 As shown, the ball track sliding pair includes a cylindrical positioning frame 8. Five sets of positioning holes are evenly spaced circumferentially on the side wall of the positioning frame 8. Each set of positioning holes includes seven positioning holes evenly spaced axially along the positioning frame 8. Elongated arc grooves 9 are formed on the inner wall of the disengagement section 3 and the side wall of the driven section 1 corresponding to each set of positioning holes. Each positioning hole contains a ball 10 with both ends extending outwards and conforming to the arc grooves 9 on the disengagement section 3 and the driven section 1. Thus, the ball track sliding pair ensures that the disengagement section 3 can only move axially relative to the driven section 1, guaranteeing the reliability of overload disengagement and reset. Simultaneously, the disengagement section 3 is completely fixed circumferentially relative to the driven section 1, ensuring stability during torque transmission.

[0034] The end face teeth 4 are respectively opened at the ends of the disengagement section 3 and the driving section 5 that are close to each other. The teeth of the end face teeth 4 on the disengagement section 3 and the teeth of the end face teeth 4 on the driving section 5 are both conical and interlocking. In engineering, if the pressure angle of the end face teeth used is... α If the module of the end face tooth is m and the number of teeth on the end face tooth is z, then the axial force on end face tooth 4 is... Under normal operating conditions of the safety shaft, the pressure F on the preload spring 2 should be greater than the axial force on the end face tooth 4. ,Right now From this, it can be deduced that This formula can be used to verify whether the selected parts meet the engineering requirements.

[0035] like Figure 7 and Figure 8As shown, the locking mechanism includes five T-shaped limiting grooves 11 evenly spaced along the circumferential direction on the inner wall of the disengagement section 3. Each limiting groove 11 is arranged radially narrowing along the disengagement section 3. A T-shaped locking wedge 12 with its bottom end extending outward is slidably fitted inside the limiting groove 11. A compression spring 13 is connected between the top of the locking wedge 12 and the bottom of the limiting groove 11. A locking groove 14 with a size adapted to the bottom end of each locking wedge 12 is opened on the side wall of the driven section 1. When the safety shaft is transmitting torque normally, the locking wedge 12 is located outside the locking groove 14, and the locking groove 14 is located behind the locking wedge 12 in the same axial direction, that is, close to the end of the preload spring 2. When overload protection is applied, the locking wedge 12 retracts synchronously with the disengagement section 3 and is pushed into the locking groove 14 under the action of the compression spring 13. The locking wedge 12 has two ends along the axial direction of the release section 3, namely the front vertical surface and the rear bottom inward slope surface. One end of the slope surface is close to the pre-tightening spring 2, which makes it easy for the locking wedge 12 to fall into the locking groove 14 during the retraction process. The front vertical surface can resist the locking wedge 12 from rebounding and disengaging after it falls into the locking groove 14.

[0036] Example 2 This invention provides a torque transmission method for a reusable torque-adjustable safety shaft applicable to installation spaces with limited capacity. During operation, power is input from the driving section 5. After the driving section 5 rotates, the torque is transmitted to the disengagement section 3 via the end face teeth 4. Because the teeth of the end face teeth 4 have a tapered structure with contracted tooth tips, the disengagement section 3 is driven by the driving section 5 in both circumferential and axial directions. The circumferential force transmits torque to the disengagement section 3, while the axial force is less than the preload of the adjusted preload spring 2, thus ensuring that the driving section 5 will not push the disengagement section 3 open during torque transmission. The torque is then transmitted to the driven section 1 via a ball-track sliding pair between the disengagement section 3 and the driven section 1. During transmission, the arc groove 9 on the disengagement section 3 drives the arc groove 9 on the driven section 1 and the driven section 1 to rotate circumferentially via the balls 10 in the positioning frame 8. Finally, the driven section 1 drives the external load, thus achieving torque transmission. At this time, the locking wedge 12 is located in front of the locking groove 14, one end of the compression spring 13 is in a compressed state, and the disengagement section 3 is engaged with the driving section 5 through the end face teeth 4 under the pre-tightening force of the pre-tightening spring 2.

[0037] Example 3 This invention provides an overload protection method for a reusable torque-adjustable safety shaft applicable to installation spaces with limited space. When overloaded, the driven section 1 is obstructed and stops rotating. The torque output by the motor through the driving section 5 is greater than the torque output under normal conditions (usually twice). At this time, the axial force on the disengagement section 3 by the end face tooth 4 increases significantly and exceeds the preload force of the preload spring 2 obtained by adjustment, thereby pushing the disengagement section 3 backward. The arc groove 9 on the disengagement section 3 moves axially along the arc groove 9 on the driven section 1 via the positioning frame 8. After the disengagement section 3 moves axially synchronously, it compresses the preload spring 2. The disengagement section 3 disengages from the driving section 5, and the torque transmission is disconnected here, cutting off the power transmission and realizing overload protection without mechanical breakage. After the detachment section 3 moves axially and disengages, the locking wedge 12 in the limiting slide groove 11 moves back synchronously with the detachment section 3 to the top of the locking groove 14. At this time, the compression spring 13 releases its potential energy and extends to push the locking wedge 12 outward along the limiting slide groove 11 and into the locking groove 14, thereby locking the detachment section 3 in the detached position, preventing the detachment section 3 from accidentally resetting, and avoiding frequent tooth collisions between the active section 5 and the detachment section 3.

[0038] Example 4 This invention provides a reset method for a reusable torque-adjustable safety shaft applicable to installation spaces with limited space. To facilitate manual reset of the locking mechanism, the disengagement section 3 is machined into two parts: a disengagement body 31 and a disengagement auxiliary section 32, coaxially connected by bolts. The disengagement body 31 is located near the driving section 5 and has end face teeth 4, and a ball bearing sliding pair is installed between it and the driven section 1. The disengagement auxiliary section 32 is located near the preload spring 2 and has a locking mechanism on its inner wall. During reset, the operator must follow these steps: First, the entire safety shaft is pulled out of the installation space by pulling away shaft 17; Next, after removing the small round nut 19, remove the driving section 5; loosen the large round nut 7 until the small diameter section of the driven section 1 is close to the shaft shoulder 6; Then, use a disassembly tool to remove the connecting bolts between the release section body 31 and the release auxiliary section 32; pull out the release section body 31 and the release auxiliary section 32 axially along the small diameter section of the driven section 1, and the locking wedge 12 detaches from one end of the limiting slide groove 11 axially (the compression spring 13 can be fixed to the bottom of the limiting slide groove 11, but only abuts against the top of the locking wedge 12), and remove the locking wedge 12 from the locking groove 14; put the removed locking wedge 12 back into the limiting slide groove 11 and compress the compression spring 13, and adjust the front and rear position of the release auxiliary section 32 until the locking wedge 12 is located in front of the locking groove 14, that is, away from the pre-tightening spring 2; reconnect the release section body 31 and the release auxiliary section 32; Then, install the active section 5 and the small round nut 19; tighten the large round nut 7 to the preset overload protection torque position; Finally, the entire safety shaft was reinstalled in its original position.

[0039] Example 5 This invention provides a reusable torque-adjustable safety shaft suitable for installations with limited space. The assembly sequence is as follows: 1) Place the five sets of locking wedges 12 into the five sets of limiting slides 11 of the disengagement auxiliary section 32 one by one. The bottom of the limiting slides 11 is fixed to the compression spring 13 at the top of the locking wedges 12. Then, fix the disengagement auxiliary section 32 to the disengagement section body 31 with bolts.

[0040] 2) Insert the pull-off shaft 17 into the inner ring of the bearing 16, and then fix the outer ring of the bearing 16 into the mounting blind hole 15.

[0041] 3) Screw the large round nut 7 into the small diameter section of the driven section 1, and then put on the large stop washer 18 and the preload spring 2 in sequence.

[0042] 4) Fit the positioning bracket 8 into the small diameter section of the driven section 1, align a set of positioning holes with a circular arc groove 9, and then place a ball bearing 10 into each positioning hole. The inner end of the ball bearing 10 falls into the circular arc groove 9 on the driven section 1.

[0043] 5) Insert the release section 3 into the small diameter section of the driven section 1, release the additional section 32 to the preload spring 2, the locking wedge block 12 is located in front of the locking groove 14, the arc groove 9 on the release section body 31 is embedded in each set of balls 10, and the end face teeth 4 on the release section body 31 are forward.

[0044] 6) Insert the driving section 5 into the small diameter section of the driven section 1, so that its end face teeth 4 mesh with the end face teeth 4 on the disengagement section body 31, then screw in the small round nut 19, and finally bend the outer tongue of the small stop washer 20 to lock it.

[0045] Example 6 This invention provides a reusable torque-adjustable safety shaft suitable for installations with limited space, with a typical application example being the rocker arm of a coal mining machine. Figure 9 As shown, in a highly integrated layout, the arrangement of components is compressed to its limit, thus severely restricting the installation space of the safety shaft: only a tiny gap is left radially between the inner hole of the motor and the outer circle of the shaft, and the shaft extension length is also limited by the structural dimensions, making it difficult to provide the additional interfaces or mounting units required by traditional independent torque limiters. This invention directly integrates the overload protection mechanism inside the drive shaft body, combining the torque limiting function with the shaft structure, thereby achieving reliable installation and operation of the safety shaft within an extremely compact space, fully demonstrating its structural adaptability and compact design advantages under complex working conditions.

Claims

1. A reusable torque-adjustable safety shaft suitable for installations with limited space, characterized in that: It includes a driven section (1), a preload spring (2) is fixedly sleeved on the driven section (1), one end of the preload spring (2) abuts against a cylindrical release section (3) sleeved on the driven section (1) via a ball track moving pair, the end of the release section (3) away from the preload spring (2) is engaged by an end face tooth (4) with a cylindrical driving section (5) rotatably sleeved on the driven section (1) along the circumferential direction, and a locking mechanism connected to the side wall of the driven section (1) is provided radially inside the end of the release section (3) near the preload spring (2).

2. The torque-adjustable safety shaft for reusable installation in limited space as described in claim 1, characterized in that, The driven section (1) is located at the end of the preload spring (2) away from the release section (3) and forms a shoulder (6) by contracting inward. The preload spring (2), the release section (3) and the driving section (5) are all located in the small diameter section of the driven section (1). A large round nut (7) is threaded on the small diameter section of the driven section (1) near the shoulder (6). The end of the preload spring (2) away from the release section (3) abuts against the large round nut (7).

3. The torque-adjustable safety shaft for use in space-constrained applications as described in claim 2, characterized in that: The large round nut (7) compresses the preload spring (2) by a certain distance. L Represented as: In the formula, T To set the preset overload torque, the screwing distance of the large round nut (7) is adjusted according to the actual torque requirements during the project. L ; K The torque coefficient of the preload spring (2) is d The nominal diameter of the large round nut (7) is... k is the elastic coefficient of the preload spring (2).

4. The torque-adjustable safety shaft for reusable installation in space-constrained environments as described in claim 1, characterized in that: The ball track moving pair includes a cylindrical positioning frame (8). Multiple sets of positioning holes are evenly spaced along the circumference on the side wall of the positioning frame (8). Each set of positioning holes includes multiple positioning holes evenly spaced along the axial direction of the positioning frame (8). The inner wall of the disengagement section (3) and the side wall of the driven section (1) are provided with long arc grooves (9) corresponding to each set of positioning holes. Each positioning hole is fitted with a ball (10) with both ends extending outward and adapted to the arc grooves (9) on the disengagement section (3) and the driven section (1).

5. The torque-adjustable safety shaft for reusable installation in space-constrained environments as described in claim 1, characterized in that: The end face teeth (4) are respectively opened at the ends of the disengagement section (3) and the active section (5) that are close to each other. The teeth of the upper end face teeth (4) of the disengagement section (3) and the teeth of the upper end face teeth (4) of the active section (5) are both conical and interlocked.

6. The applicable space-constrained, reusable torque-adjustable safety shaft as described in claim 1 or 5, characterized in that, The pressure angle of the end face tooth (4) The following requirements must be met: In the formula, m is the module of the end face tooth (4), and z is the number of teeth of the end face tooth (4). K d is the torque coefficient of the preload spring (2) and d is the diameter of the driven section (1) where the preload spring (2) is located.

7. The applicable space-constrained, reusable torque-adjustable safety shaft as described in claim 1, characterized in that, The locking mechanism includes multiple T-shaped limiting grooves (11) evenly spaced along the circumference on the inner wall of the release section (3). Each limiting groove (11) is arranged radially narrowing along the release section (3). A T-shaped locking wedge (12) with its bottom end extending outward is slidably fitted inside the limiting groove (11). A compression spring (13) is connected between the top of the locking wedge (12) and the bottom of the limiting groove (11). A locking groove (14) with its size is provided on the side wall of the driven section (1) corresponding to the bottom end of each locking wedge (12).

8. The applicable space-constrained, reusable torque-adjustable safety shaft as described in claim 1, characterized in that, The driven section (1) has an axially protruding blind hole (15) at one end near the driving section (5). A pull-off shaft (17) with one end extending outward is coaxially connected to the blind hole (15) via a bearing (16).

9. The torque transmission method for a reusable torque-adjustable safety shaft with limited installation space as described in claim 1, characterized in that, During operation, the power is input from the active section (5), transmitted to the disengagement section (3) through the end face teeth (4), and then transmitted to the driven section (1) through the ball track moving pair between the disengagement section (3) and the driven section (1), thus realizing torque transmission.

10. The overload protection method for a reusable torque-adjustable safety shaft with limited installation space as described in claim 1, characterized in that, When overloaded, the driven section (1) stops rotating due to obstruction. The driving section (5) pushes the disengagement section (3) to move axially and disengage through the end face teeth (4). Then, the locking wedge (12) in the locking mechanism moves axially to the top of the locking groove (14) and falls into the locking groove (14) under the extension of the compression spring (13) and engages with it, locking the disengagement section (3) in the disengagement position. The driving section (5) cuts off the power transmission to achieve overload protection.

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