Safety shaft and torque transmission with limited space, overload protection, reset method

Abstract

The application discloses a safety shaft suitable for limited space, torque transmission, overload protection and resetting method, which comprises a driven section, a pre-tightening spring is sleeved outside the driven section, one end of the pre-tightening spring abuts against a cylindrical disengaging section which is sleeved outside the driven section through a ball spline pair, one end of the disengaging section away from the pre-tightening spring is connected with a cylindrical driving section which is sleeved outside the driven section along the circumferential direction through a clutch mechanism, an installation blind hole is formed in the driven section corresponding to one end of the driving section along the axial direction, a cam shaft with one end extending outward is coaxially and rotationally matched in the installation blind hole, and a cam mechanism is arranged on the inner end of the cam shaft and penetrates through the driven section along the radial direction and abuts against the inner wall of the disengaging section. The torque limiting function is integrated in the transmission shaft body through integrated design, so that the overload can be quickly disengaged, reliable self-locking after disengagement and convenient manual resetting can be realized, and the torque transmission and overload protection can be completed without destroying the continuity and mechanical integrity of the transmission shaft structure.

Description

Technical Field

[0001] This invention belongs to the field of mechanical transmission and overload protection technology, specifically relating to a reusable rotary reset safety shaft suitable for installation in limited space. This invention also relates to a torque transmission method for a reusable rotary reset safety shaft suitable for installation in limited space. Furthermore, this invention relates to an overload protection method for a reusable rotary reset safety shaft suitable for installation in limited space. Finally, this invention relates to a reset method for a reusable rotary reset safety shaft suitable for installation in limited space. Background Technology

[0002] In various mechanical transmission systems, such as automated production lines, packaging machinery, machine tools, printing equipment, and robots, power is typically transmitted between the drive motor and the actuator via a drive shaft. However, during equipment operation, abnormal overload torque may occur due to factors such as workpiece jamming, misoperation, program errors, or sudden load changes. If the transmission system lacks overload protection, this torque will be directly transmitted to the motor, reducer, and precision transmission components, potentially leading to equipment downtime, permanent deformation or breakage of transmission components, or even safety accidents, resulting in economic losses and production interruptions.

[0003] To prevent the aforementioned problems, torque limiters, as a critical protective device, are widely used in drive chains. Their core function is to quickly and reliably cut off power transmission when the transmitted torque exceeds a preset safety threshold, thereby protecting upstream and downstream equipment; simultaneously, they can easily restore transmission function after the fault is cleared. Based on their overload response principle and reset method, existing torque limiters can be mainly classified into the following categories: 1) Shear pin type torque limiter: This type belongs to the traditional overload protection method. It transmits torque through a pin with precisely calculated mechanical properties. When an overload occurs, the pin is sheared and breaks, thus disconnecting the power. Its advantages are simple structure, low cost, and well-defined trigger threshold. However, its disadvantages include: after each overload, the machine must be stopped to replace the damaged pin, making maintenance inconvenient and downtime long; the debris generated by the breakage may contaminate the equipment environment, making it unsuitable for applications with high cleanliness requirements; furthermore, it is a one-time destructive protection device and cannot achieve rapid reset.

[0004] 2) Friction-type torque limiter: This type of torque limiter transmits torque by pressing a friction plate with a spring assembly. Overload causes the friction surface to slip. Its advantages include continuous and precise setting of the overload torque through spring preload adjustment, and the ability to reuse the device without replacing parts after an overload. Its main disadvantages are: significant frictional heat is generated during slippage, potentially leading to degradation or thermal deformation of the friction material; long-term slippage causes wear, requiring regular maintenance or replacement of the friction plate; response sensitivity is affected by the stability of the friction coefficient, exhibiting a certain degree of hysteresis; and it typically requires lubrication or cooling, resulting in a relatively complex structure.

[0005] 3) Ball (or roller) grooved torque limiter: This type of torque limiter uses spring-pressed balls or rollers embedded in wedge-shaped grooves on the driving and driven ends to transmit torque. In case of overload, the balls overcome the spring force and are forced out of the grooves, achieving relative rotation (disengagement) between the driving and driven ends. Its advantages include fast response, compact structure, and clear disengagement action. However, existing devices of this type have the following problems: the reset operation after disengagement often requires axial movement of one half of the coupling or disassembly of some parts, which is inconvenient; in the disengaged state, if the power end continues to operate, the balls may repeatedly impact the grooves, causing damage to parts.

[0006] Furthermore, existing mainstream torque limiters share a common problem in terms of mechanical structure integration: they are typically installed as independent, serial functional modules between two independent shaft ends of the drive unit and the load unit. This "intermediary" installation method necessitates the addition of two extra connection interfaces (such as keyways, clamping sleeves, or flanges) in the transmission path, relying on the coupling's own housing or sleeve structure to bear the entire torque. This structural form has the following drawbacks: First, the overload protection unit has a redundant structure, which weakens the stiffness and strength of the drive train: the independent modules connected in series in the drive train, the additional connection points and their fasteners, create structural redundancy and weak points. Each connection interface may introduce fitting clearance and coaxiality error, and become a stress concentration area under alternating torque, which weakens the torsional stiffness and fatigue strength of the drive train as a whole.

[0007] Second, it increases the structural size and rotational inertia of the overload protection unit: the independent module structure set on the transmission chain usually increases the axial installation space of the transmission system, and its own rotational inertia will increase the rotational inertia of the system, which is not conducive to improving the dynamic response of the system.

[0008] Third, the alignment accuracy requirements for the transmission chain installation will be increased: as an independent structural module, it has high requirements for the alignment accuracy between the drive shaft and the load shaft. Improper installation can easily cause additional radial force, which will aggravate the wear of parts and ultimately affect the power transmission.

[0009] In summary, existing torque limiters struggle to balance ease of reset, environmental adaptability, stability after disengagement, and maintenance-free operation. Shear pin type torque limiters require component replacement; friction type suffers from wear and heat generation issues; and common ball bearing type limits ease of reset and self-locking protection after disengagement. Furthermore, traditional split-type torque limiters, requiring series installation between the drive shaft and load shaft, introduce additional connection interfaces and clearances. This not only disrupts the structural continuity of the transmission shaft system, creating stress concentration, but also reduces the system's torsional stiffness and fatigue strength.

[0010] 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 a large load but also frequently suffers from unpredictable impact loads, resulting in complex operating conditions. Furthermore, due to the limited internal space of the motor, the installation layout of this shaft is very compact: the axial installation length is limited by the rocker arm housing structure, and the radial dimension is limited by the mere 1-2mm gap between the motor's inner bore and the shaft, making it difficult to arrange the commonly used shear pin type safety shaft.

[0011] Therefore, a safe shaft drive solution is needed in this field. This solution should not only possess advantages such as sensitive overload response, precise torque setting, automatic locking after disengagement, simple and quick reset, enclosed and maintenance-free structure, and no need to replace parts, but more importantly, it should achieve deep integration of the overload protection mechanism and the drive shaft. While providing overload protection, it should maintain the structural continuity, high rigidity, and high strength of the entire transmission system of the equipment or machinery as much as possible, thereby overcoming the shortcomings of traditional independent modular torque limiters. Summary of the Invention

[0012] The purpose of this invention is to provide a reusable rotational reset safety shaft suitable for installations with limited space, which solves the problems of limited space and easy weakening of shaft strength in existing series structures.

[0013] Another object of the present invention is to provide a torque transmission method for a reusable rotary reset safety shaft suitable for installation in space-constrained environments.

[0014] Another object of the present invention is to provide an overload protection method for a reusable rotary reset safety shaft applicable to installation spaces with limited space.

[0015] Another object of the present invention is to provide a reset method for a reusable rotary reset safety shaft applicable to installation spaces with limited space.

[0016] The first technical solution adopted in this invention is: a reusable rotary reset safety shaft applicable to installation space constraints, comprising 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 spline pair, the end of the release section away from the preload spring being connected via a clutch mechanism to a cylindrical driving section rotatably sleeved on the driven section, the driven section having an axially oriented blind hole in one end corresponding to the driving section, a camshaft with one end extending outwards being coaxially rotatably fitted in the blind hole, and a cam mechanism being provided at the inner end of the camshaft, which radially passes through the driven section and abuts against the inner wall of the release section.

[0017] The first technical solution of the present 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.

[0018] The screw-in distance of the large round nut compressing the preload spring L Represented as:

[0019] 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.

[0020] The ball spline pair includes multiple guide tiles that are fixedly attached to the driven section at uniform intervals along the circumference, corresponding to the disengagement section. The inner wall of the disengagement section is provided with guide grooves that are uniformly spaced along the circumference and fit into the multiple guide tiles one by one. The guide tiles on both sides of the fitting position and the inner wall of the disengagement section are recessed inward to form a semi-cylindrical receiving groove. A number of spline balls are uniformly arranged along the length direction in the cylindrical receiving groove formed by the two sides of the fitting position.

[0021] The clutch mechanism includes several tapered grooves evenly spaced along the circumference at the end of the active section near the disengagement section, and grooves evenly spaced along the circumference at the end of the disengagement section near the active section, each corresponding to one of the tapered grooves. Each pair of grooves and tapered grooves forms a cavity in which a clutch ball of appropriate size is placed.

[0022] The cam mechanism includes multiple arc-shaped grooves connected end-to-end in the circumferential direction inside the camshaft. The arc of each arc-shaped groove gradually expands outward from the tail end to the head end. Limiting blocks are set between the head and tail ends of two adjacent arc-shaped grooves. Circumferentially, annular guide holes are opened on the side wall of the camshaft corresponding to the positions of the multiple arc-shaped grooves. A T-shaped guide rod is set in each arc-shaped groove. The head of the guide rod slides in fit with the arc-shaped groove. The tail of the guide rod extends out of the camshaft through the guide hole and is fixedly connected to a telescopic cylinder that extends outward through the driven section. The end of the telescopic cylinder away from the guide rod is open and slidably fitted with a wedge-shaped block that extends outward. A locking spring is connected between the inner end of the wedge-shaped block and the inner end wall of the telescopic cylinder. The inner wall of the disengagement section near the driving section has an outwardly flared ramp in the circumferential direction. The outer end of the wedge-shaped block abuts against the ramp surface and is in static friction fit with it.

[0023] A ring-shaped handle base is coaxially fixed to the outer end of the camshaft, and a reset handle is fixed to the outer wall of the handle base.

[0024] The second technical solution adopted in this invention is: a torque transmission method for a reusable rotary reset safety shaft with limited installation space. During operation, power is input from the driving section, transmitted to the disengagement section through the clutch mechanism, and then transmitted to the driven section through the ball spline 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 rotary reset safety shaft with limited installation space. When overloaded, the driven section is blocked and stops rotating. The driving section pushes the clutch ball in the clutch mechanism to move axially, causing the disengagement section to disengage from the driving section. Then, the wedge block in the cam mechanism is further pushed out of the telescopic cylinder under the action of the locking spring and statically frictionally engages with the ramp of the disengagement section, locking the disengagement section in the disengagement position. The power transmission of the driving section is cut off to achieve overload protection.

[0026] The fourth technical solution adopted in this invention is: a reset method for a reusable rotary reset safety shaft applicable to installation spaces with limited space. During reset, the operator rotates the outer end of the camshaft, driving the guide rod in the cam mechanism to slide from the first end to the last end of the arc groove. The wedge block retracts inward with the telescopic cylinder, releasing the lock on the disengagement section. Under the extension of the pre-tension spring, the disengagement section returns to the meshing state with the active section. Subsequently, the operator rotates the camshaft in the opposite direction, driving the guide rod to slide from the last end to the first end of the arc groove. The wedge block pushes outward with the telescopic cylinder and statically frictionally engages with the slope of the disengagement section, locking the disengagement section in the meshing position. The power transmission of the active section is restored, achieving reset.

[0027] The beneficial effects of this invention are: This invention is applicable to space-constrained safety shafts and torque transmission, overload protection, and reset methods. Through integrated design, the torque limiting function is integrated into the transmission shaft body, which not only enables rapid overload release, reliable self-locking after release, and convenient manual reset, but also completes torque transmission and overload protection without destroying the structural continuity and mechanical integrity of the transmission shaft, effectively overcoming the negative impact of traditional independent modular structures on the stiffness and fatigue strength of the transmission shaft system. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall structure of the reusable rotary reset safety shaft applicable to installation spaces of the present invention; Figure 2 This is a partial structural diagram of a reusable rotary reset safety shaft applicable to installation spaces limited by the present invention; Figure 3 This is an axial cross-sectional schematic diagram of a reusable rotary reset safety shaft applicable to installation spaces limited by the present invention; Figure 4 This is a schematic diagram of the driven section in a reusable rotary reset safety shaft applicable to installation spaces of the present invention; Figure 5 This is a partial structural diagram of the ball spline pair in the reusable rotary reset safety shaft applicable to installation space in this invention; Figure 6 This is a radial cross-sectional view of the ball spline pair in a reusable rotary reset safety shaft applicable to installation space constraints, as described in this invention. Figure 7 This is a schematic diagram of the disengagement section in a reusable rotary reset safety shaft applicable to installation spaces of the present invention; Figure 8 This is a schematic diagram of the active section of a reusable rotary reset safety shaft applicable to installation spaces in this invention; Figure 9 This is a schematic diagram of the camshaft structure in the reusable rotary reset safety shaft applicable to installation space of the present invention; Figure 10 This is a schematic diagram of the cam mechanism in a reusable rotary reset safety shaft applicable to installation spaces in this invention. Figure 11 This is a radial cross-sectional schematic diagram of the cam mechanism in a reusable rotary reset safety shaft applicable to installation space of the present invention; Figure 12 This is a schematic diagram showing the state of the guide rod in the arc-shaped groove of the reusable rotary reset safety shaft with limited installation space, applicable to the present invention. Figure 13 This is a schematic diagram showing the state of the guide rod near the end of the arc-shaped groove in a reusable rotary reset safety shaft with limited installation space, applicable to the present invention. Figure 14 This is a schematic diagram illustrating an application scenario for the invention of a reusable rotary reset safety shaft with limited installation space.

[0029] In the diagram, 1. Driven section, 2. Preload spring, 3. Disengagement section, 4. Driven section, 5. Mounting blind hole, 6. Camshaft, 7. Shoulder, 8. Large round nut, 9. Guide bearing, 10. Guide groove, 11. Receiving groove, 12. Splined ball, 13. Tapered groove, 14. Groove, 15. Clutch ball, 16. Arc groove, 17. Limit stop, 18. Guide hole, 19. Guide rod, 20. Telescopic cylinder, 21. Wedge block, 22. Locking spring, 23. Ramp, 24. Positioning sleeve, 25. Positioning spring, 26. Handle base, 27. Reset handle, 28. Bearing, 29. Small round nut, 30. Large stop washer, 31. Small stop washer, 32. Camshaft end cap, 33. Fastening bolt, 34. Motor housing end cap, 35. Motor housing. Detailed Implementation

[0030] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0031] Example 1 This invention provides a reusable rotational reset safety shaft suitable for installations with limited space, such as... Figures 1 to 3 As shown, the device includes a driven section 1, with a preload spring 2 fixedly sleeved on the outside of the driven section 1. One end of the preload spring 2 abuts against a cylindrical release section 3, which is sleeved on the outside of the driven section 1 via a ball spline pair. The end of the release section 3 away from the preload spring 2 is connected via a clutch mechanism to a cylindrical driving section 4, which is circumferentially rotatable on the outside of the driven section 1. A blind mounting hole 5 is axially formed in the end of the driven section 1 corresponding to the driving section 4. A camshaft 6 with one end extending outward is coaxially rotatably fitted in the blind mounting hole 5. The outer end of the blind mounting hole 5 expands radially outward to form a step, on which a... The bearing 28 is fixedly sleeved on the outer side of the camshaft 6, allowing the camshaft 6 to rotate relative to the mounting blind hole 5. The inner end of the camshaft 6 is provided with a cam mechanism that passes radially through the driven section 1 and abuts against the inner wall of the disengagement section 3. The outer end of the camshaft 6 is coaxially fixedly sleeved with an annular handle base 26. A reset handle 27 is fixed on the outer wall of the handle base 26. The outer side of the handle base 26 is a motor housing end cover 34 that is movably fitted with it. The motor housing end cover 34 is bolted to the motor housing 35. A sealing ring is installed in the handle base 26 to prevent external dust from entering.

[0032] like Figure 4 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 7. The preload spring 2, disengagement section 3, and driving section 4 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 4 and the driven section 1 for power input and output, thus achieving an integrated design. A large round nut 8 is threadedly connected to the small-diameter section of the driven section 1 near the shoulder 7. The end of the preload spring 2 furthest from the disengagement section 3 abuts against the large round nut 8, which limits its movement, thereby applying an axial preload force towards the driving section 4 to the disengagement section 3. The threaded section has a groove for engaging the inner tongue of the large stop washer 30. The large stop washer 30 is installed on one end of the large round nut 8. After tightening the large round nut 8 to a sufficient preload force, the outer tongue of the large stop washer 30 is bent to achieve locking. The preload force provided by the large round nut 8 is adjusted by adjusting the screw-in distance of the large round nut 8. Let the screw-in distance be L, the overload protection torque be T, the nominal diameter of the large round nut 8 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 8 can be calculated by substituting the pressure F into Hooke's Law ( It is derived that, i.e. The large round nut 8 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 8. 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.

[0033] The active section 4, away from the disengagement section 3, is provided with a small round nut 29 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 31. The small stop washer 31 is installed on one end of the small round nut 29. After the active section 4 is axially positioned away from the load by the small round nut 29, the outer tongue of the small stop washer 31 is bent to abut against the cut of the small round nut 29, thereby achieving locking and preventing loosening.

[0034] like Figures 5 to 7 As shown, the ball spline pair includes multiple guide tiles 9 that are fixedly attached to the driven section 1 at uniform intervals along the circumference, corresponding to the disengagement section 3. The guide tiles 9 can be integrally formed with the driven section 1 to ensure stability. The inner wall of the disengagement section 3 has guide grooves 10 that are uniformly spaced along the circumference and fit into the multiple guide tiles 9 one by one. The guide tiles 9 on both sides of the fitting position and the inner wall of the disengagement section 3 are recessed inward to form a semi-cylindrical receiving groove 11. Several spline balls 12 are evenly arranged along the length direction in the cylindrical receiving groove 11 formed by the two sides of the fitting position. Thus, the ball spline pair enables the disengagement section 3 to move only axially relative to the driven section 1, resulting in low friction, sensitive response, and smooth sliding, ensuring the reliability of overload disengagement and reset. At the same time, the disengagement section 3 is completely fixed circumferentially relative to the driven section 1, ensuring stability when transmitting torque.

[0035] like Figure 7 and Figure 8 As shown, the clutch mechanism includes twelve conical grooves 13 evenly spaced along the circumference at one end of the active section 4 near the disengagement section 3, and twelve grooves 14 evenly spaced along the circumference at one end of the disengagement section 3 near the active section 4, corresponding one-to-one with the twelve conical grooves 13. Each pair of grooves 14 and conical grooves 13 forms a cavity in which a clutch ball 15 of appropriate size and tight fit is placed.

[0036] like Figures 9 to 11 As shown, the cam mechanism includes four arc-shaped grooves 16 connected end-to-end in the circumferential direction inside the camshaft 6. The arc of each arc-shaped groove 16 gradually expands outward from the tail end to the head end, that is, the tail end is close to the center of the camshaft 6 and the head end is outward. A limit stop 17 is provided between the head and tail ends of two adjacent arc-shaped grooves 16. An annular guide hole 18 is provided in the circumferential direction on the side wall of the camshaft 6 corresponding to the positions of the four arc-shaped grooves 16. During processing, as shown... Figure 10As shown, the arc groove 16 can be machined on the end of the camshaft 6 first, and then the annular guide hole 18 can be formed by adding the camshaft end cover 32. The camshaft end cover 32 and the camshaft 6 are fastened together by coaxial fastening bolts 33. Each arc groove 16 has a mounting groove with a width greater than the guide hole 18 that is radially outward at its tail end. Each arc-shaped groove 16 is provided with a T-shaped guide rod 19. The head of the guide rod 19 slides in the arc-shaped groove 16. During installation, the head of the guide rod 19 enters the arc-shaped groove 16 through the mounting groove. The tail of the guide rod 19 extends out of the camshaft 6 through the guide hole 18 and is fixedly connected to a telescopic cylinder 20 that extends outward through the driven section 1. The annular opening of the guide hole 18 provides relative movement space for the guide rod 19 when the camshaft 6 rotates. A circular through hole with an outer diameter of the telescopic cylinder 20 is provided at the position where the telescopic cylinder 20 extends outward through the driven section 1. The end of the telescopic cylinder 20 away from the guide rod 19 is open and slides in a wedge-shaped block 21 with one end extending outward. A locking spring 22 is connected between the inner end of the wedge block 21 and the inner end wall of the telescopic cylinder 20. The inner wall of the disengagement section 3 near the driving section 4 has an outwardly flared ramp 23 along the circumference. The outer end of the wedge block 21 abuts against the slope surface of the ramp 23 and is in static frictional engagement with it. A positioning sleeve 24 is coaxially fixed to the front of the inner end of the camshaft 6. A positioning spring 25 with one end extending outward and abutting against the inner end wall of the mounting blind hole 5 is coaxially fixed inside the positioning sleeve 24, which is used to achieve axial positioning and buffering of the camshaft 6.

[0037] In the cam mechanism, to ensure the self-locking reliability of the wedge block 21, the inclined plane angle is... The self-locking condition should be met: ,Right now For the safety shaft of the rocker arm of a coal mining machine in a certain coal mine, the material of the self-locking inclined surface is 40CrNiMo, and its surface roughness is Ra3.2. Under the condition of no lubrication and dry friction, the static friction coefficient is taken as... When the value is 0.20, its self-locking critical angle can be calculated using the above formula. To ensure reliable self-locking, the slope angle is... It should not exceed 11.31°.

[0038] Example 2 This invention provides a torque transmission method for a reusable rotary reset safety shaft applicable to installation spaces with limited space. During operation, power is input from the driving section 4. After the driving section 4 rotates, the torque is transmitted to the disengagement section 3 via clutch balls 15. Because the side walls of the tapered groove 13 of the driving section 4 are outwardly flared inclined surfaces, the clutch balls 15 are subjected to driving forces in both the circumferential and axial directions of the tapered groove 13. The circumferential force is transmitted to the groove 14 via the clutch balls 15, and then to the disengagement section 3. The axial force is less than the preload of the adjusted preload spring 2, thus ensuring that the clutch balls 15 will not push the disengagement section 3 open during torque transmission. The torque is then transmitted to the driven section 1 via the ball spline pair between the disengagement section 3 and the driven section 1. During transmission, the guide groove 10 on the disengagement section 3 drives the guide bearing 9 on the driven section 1 to rotate circumferentially via the spline balls 12 in the receiving groove 11. Finally, the driven section 1 drives the external load, thus achieving torque transmission. At this time, the guide rod 19 and the telescopic cylinder 20 are located at the first end of the arc groove 16, that is, the telescopic cylinder 20 is extended. The wedge block 21 abuts against the slope 23 and the locking spring 22 is in a compressed state. The disengagement section 3 is engaged with the driving section 4 through the clutch ball 15 under the pre-tightening force of the pre-tightening spring 2.

[0039] Example 3 This invention provides an overload protection method for a reusable rotary reset 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 4 is greater than the torque output under normal conditions (usually twice). At this time, the clutch ball 15 is subjected to a significantly increased axial force from the tapered groove 13, which exceeds the preload force of the adjusted preload spring 2. This causes the clutch ball 15 to push open the disengagement section 3 through the groove 14. After being pushed open, the clutch ball 15 disengages from the cavity formed by the tapered groove 13 and the groove 14, and the torque transmission is interrupted. The guide groove 10 moves axially relative to the guide bearing 9. After the disengagement section 3 moves axially synchronously, it compresses the preload spring 2. The disengagement section 3 disengages from the driving section 4, cutting off the power transmission and achieving overload protection without mechanical breakage. After the detachment section 3 moves axially and disengages, the ramp 23 moves axially and disengages from the wedge block 21. After the wedge block 21 loses radial pressure, the locking spring 22 extends and pushes the wedge block 21 further out of the telescopic cylinder 20 and engages with the ramp 23 near the active section 4 again through static friction, thereby locking the detachment section 3 in the disengaged position and preventing the detachment section 3 from accidentally resetting.

[0040] Example 4 This invention provides a reset method for a reusable rotary reset safety shaft applicable to installation spaces with limited space, such as... Figure 12 and Figure 13As shown, during reset, the operator rotates the camshaft 6 via the reset handle 27, driving the guide rod 19 to slide along the guide hole 18 from the beginning of the arc groove 16 to the position of the tail limit block 17. The wedge block 21 retracts inward with the telescopic cylinder 20, releasing the lock on the disengagement section 3. Under the extension of the preload spring 2, the disengagement section 3 resumes engagement with the drive section 4. The clutch ball 15 re-fits tightly in the cavity formed by the tapered groove 13 and the groove 14. Subsequently, the operator rotates the camshaft 6 in the opposite direction, driving the guide rod 19 to slide from the tail end of the arc groove 16 to the beginning. The wedge block 21 pushes outward again with the telescopic cylinder 20 and statically rubs against the end of the ramp 23 away from the drive section 4. The locking spring 22 is compressed, thereby locking the disengagement section 3 in the engagement position. The power transmission of the drive section 4 is restored, achieving reset.

[0041] Example 5 This invention provides a reusable rotational reset safety shaft suitable for installations with limited space. The assembly sequence is as follows: 1) Assemble the cam mechanism: Install the positioning spring 25 and positioning sleeve 24 into the blind hole 5 of the driven section 1, and cover the camshaft 6 with the camshaft end cover 32 and fix it with the fastening bolt 33.

[0042] 2) Install the camshaft 6 into the mounting blind hole 5 via the bearing 28, and press it against the positioning spring 25.

[0043] 3) Install the large round nut 8, the large stop washer 30, the preload spring 2, and the relevant gaskets for the release section.

[0044] 4) Install the locking spring 22 and the wedge block 21 into the telescopic cylinder 20.

[0045] 5) Four sets of telescopic cylinders 20 and guide rods 19 are respectively installed through the four circular through holes on the side of the driven section 1. The T-shaped heads of the four guide rods 19 extend into the arc-shaped groove 16 along the four mounting grooves reserved in the annular guide hole 18.

[0046] 6) Place the disengaged segment 3 onto the driven segment 1.

[0047] 7) Insert the spline ball 12 into the receiving groove 11 of the driven section 1, install the end plugs of the receiving groove 11 and fix them with fastening bolts.

[0048] 8) Insert the clutch ball 15 into the tapered groove 13 of the drive section 4 and mate it with the groove 14 of the disengagement section 3.

[0049] 9) Place the small stop washer 31 onto the shaft section with the opening at one end of the driven section 1, so that its inner tongue is embedded in the preset groove on the shaft section; then screw on the small round nut 29 and tighten it to the set position, and bend the outer tongue of the small stop washer 31 into the corresponding cut of the small round nut 29 to achieve the locking and anti-loosening of the small round nut 29.

[0050] 10) Insert the inner tongue of the large locking washer 30 into the corresponding slot on the shaft section, adjust the large round nut 8 until the preload is reached, and then bend the outer tongue of the large locking washer 30 into the corresponding cut on the outer circumference of the large round nut 8 to complete the locking and anti-loosening.

[0051] 11) Install the relevant components of the reset handle 27.

[0052] This invention combines a closed cam structure with a ball clutch mechanism to achieve functions such as rapid overload response, reliable self-locking after disengagement, and convenient manual reset, without the need to replace any parts. It is suitable for overload protection applications in various mechanical transmission systems.

[0053] Example 6 This invention provides a reusable rotary reset safety shaft suitable for installations with limited space, with the rocker arm of a coal mining machine as a typical application example, such as... Figure 14 This invention demonstrates its installation in an extremely space-constrained environment. The components are highly integrated within the rocker arm housing, creating strict limitations on the installation space for the safety shaft: a radial clearance of only 1-2 mm is allowed between the motor's inner bore and the outer diameter of the shaft; the axial length is also limited by the rocker arm housing structure, making it impossible to accommodate the additional mounting interfaces or modules required for traditional independent torque limiters. By integrating the overload protection mechanism inside the shaft and employing a ball spline and cam self-locking structure, this invention successfully achieves reliable installation and stable operation in such enclosed and compact spaces, fully demonstrating its structural compactness and assembly adaptability under complex working conditions.

Claims

1. A reusable rotary reset safety shaft suitable for installation in limited space, characterized in that: 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 through a ball spline pair, the end of the release section (3) away from the preload spring is connected to a cylindrical driving section (4) sleeved on the driven section in a circumferential direction through a clutch mechanism, a blind hole (5) is provided in the driven section (1) corresponding to the driving section (4) in an axial direction, a camshaft (6) with one end extending outward is coaxially rotated in the blind hole (5), and a cam mechanism is provided at the inner end of the camshaft (6) that passes radially through the driven section and abuts against the inner wall of the release section (3).

2. The reusable rotational reset safety shaft applicable to installation spaces with limited capacity 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 (7) by contracting inward. The preload spring (2), the release section (3) and the driving section (4) are all located in the small diameter section of the driven section (1). A large round nut (8) is threaded on the small diameter section of the driven section (1) near the shoulder (7). The end of the preload spring (2) away from the release section (3) abuts against the large round nut (8).

3. The reusable rotational reset safety shaft applicable to installation spaces with limited capacity as described in claim 2, characterized in that, The large round nut (8) compresses the preload spring (2) by a certain distance. L Represented as: In the formula, T To achieve the preset overload torque, the screwing distance of the large round nut (8) 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 (8) is... k is the elastic coefficient of the preload spring (2).

4. The reusable rotational reset safety shaft applicable to installation spaces with limited capacity as described in claim 1, characterized in that, The ball spline pair includes multiple guide tiles (9) that are fixedly attached to the driven section (1) and the disengagement section (3) at uniform intervals along the circumference. The inner wall of the disengagement section (3) is provided with guide grooves (10) that are uniformly spaced along the circumference and are fitted into the multiple guide tiles (9) one by one. The guide tiles (9) on both sides of the fitting position and the inner wall of the disengagement section (3) are recessed inward to form a semi-cylindrical receiving groove (11). A number of spline balls (12) are evenly arranged along the length direction in the cylindrical receiving groove (11) formed by the two sides of the fitting position.

5. The reusable rotary reset safety shaft applicable to installation spaces with limited capacity as described in claim 1, characterized in that, The clutch mechanism includes a number of conical grooves (13) evenly spaced along the circumference at one end of the active section (4) near the disengagement section (3). The disengagement section (3) is provided with grooves (14) evenly spaced along the circumference at one end of the active section (4) that correspond one-to-one with the number of conical grooves (13). Each pair of grooves (14) and the conical grooves (13) form a cavity in which a clutch ball (15) of appropriate size is placed.

6. The reusable rotational reset safety shaft applicable to installation spaces with limited capacity as described in claim 1, characterized in that, The cam mechanism includes multiple arc-shaped grooves (16) connected end-to-end in the circumferential direction inside the camshaft (6). The arc of each arc-shaped groove (16) gradually expands outward from the tail end to the head end. A limit stop (17) is provided between the head and tail ends of two adjacent arc-shaped grooves (16). An annular guide hole (18) is provided in the circumferential direction on the side wall of the camshaft (6) corresponding to the position of the multiple arc-shaped grooves (16). A T-shaped guide rod (19) is provided in each arc-shaped groove (16). The head of the guide rod (19) slides with the arc-shaped groove (16), and the tail of the guide rod (19) slides with the arc-shaped groove (16). The part extends out of the camshaft (6) through the guide hole (18) and is fixedly connected to the telescopic cylinder (20) that extends outward through the driven section (1). The telescopic cylinder (20) is open at one end away from the guide rod (19) and is slidably fitted with a wedge block (21) that extends outward. A locking spring (22) is connected between the inner end of the wedge block (21) and the inner end wall of the telescopic cylinder (20). The inner wall of the disengagement section (3) near the driving section (4) is provided with an outwardly flared ramp (23) along the circumferential direction. The outer end of the wedge block (21) abuts against the slope (23) and is in static friction fit with it.

7. The reusable rotational reset safety shaft applicable to installation spaces with limited capacity as described in claim 1, characterized in that, The outer end of the camshaft (6) is coaxially fixedly sleeved with an annular handle base (26), and a reset handle (27) is fixed on the outer wall of the handle base (26).

8. The torque transmission method for a reusable, rotationally resettable safety shaft applicable to installation space-constrained locations, as described in claim 1, is characterized in that... During operation, power is input from the active section (4), transmitted to the disengagement section (3) through the clutch mechanism, and then transmitted to the driven section (1) through the ball spline pair between the disengagement section (3) and the driven section (1), thus realizing torque transmission.

9. The overload protection method for a reusable rotary reset 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 (4) pushes the clutch ball (15) in the clutch mechanism to move axially, causing the disengagement section (3) to disengage from the driving section (4). Then, the wedge block (21) in the cam mechanism is pushed out of the telescopic cylinder (20) under the extension of the locking spring (22) and statically frictionally engages with the ramp (23) of the disengagement section (3), locking the disengagement section (3) in the disengagement position. The driving section (4) cuts off the power transmission to achieve overload protection.

10. The reset method for a reusable rotary reset safety shaft with limited installation space as described in claim 1, characterized in that, When resetting, the operator rotates the camshaft (6), driving the guide rod (19) in the cam mechanism to slide from the first end of the arc groove (16) to the last end. The wedge block (21) retracts inward with the telescopic cylinder (20) to release the lock on the disengagement section (3). Under the extension of the preload spring (2), the disengagement section (3) resumes the engagement state with the active section (4). Then, the operator rotates the camshaft (6) in the opposite direction, driving the guide rod to slide from the last end of the arc groove to the first end. The wedge block pushes outward with the telescopic cylinder and makes static friction cooperation with the slope of the disengagement section, locking the disengagement section (3) in the engagement position. The power transmission of the active section (4) is restored to achieve resetting.

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