Low-torque over-torque detection structure and low-torque adjusting type electric actuator

Abstract

The utility model relates to the field of electric actuators, and particularly discloses a low-torque over-torque detection structure and a low-torque adjusting type electric actuator, the low-torque over-torque detection structure comprises a worm gear, a worm sleeve and a mounting shaft, the mounting shaft is rotatably arranged in the actuator and coaxially connected with an output shaft of a driving part, the worm sleeve is arranged on the mounting shaft in a sleeving manner and synchronously rotates with the mounting shaft, and the worm sleeve is rotatably connected with the worm gear. The worm gear is rotationally arranged in the actuator and meshed with the outer side wall of the worm sleeve, the worm sleeve can slide back and forth in the axial direction of the mounting shaft, the two ends of the mounting shaft are sleeved with fixing rings, elastic pieces are arranged at the positions, located between the worm sleeve and the two fixing rings, of the mounting shaft, the elastic pieces apply tension between the worm sleeve and the fixing rings, and each elastic piece comprises a compression spring. The compression spring is of a spiral structure and can bear pressure in the axial direction, the pretightening force of the worm sleeve can be adjusted through the compression spring under the condition that a mold is not opened again, and then different over-torsion detection requirements of the actuator are met. The utility model has the effects of small trigger torque and graded adjustment.

Description

Technical Field

[0001] This application relates to the field of electric actuators, and in particular to a low-torque over-torque detection structure and a low-torque adjustable electric actuator. Background Technology

[0002] An electric actuator is a drive device that provides linear or rotary motion. It is a commonly used actuator in industrial automation control. Its function is to receive commands and signals from the electrical control cabinet and drive the corresponding mechanism to perform corresponding actions. The over-torque device in the electric actuator is mainly used to detect the output torque of the electric actuator and to control the motor to cut off power in case of overload to avoid damage to the motor.

[0003] Chinese patent application number CN209894377U provides an intelligent electric actuator torque detection mechanism with a backlash elimination device. It includes a worm gear fixed shaft, a deep groove ball bearing, a body, a worm sleeve, a worm wheel, disc springs, an eccentric crank arm component, and a potentiometer assembly. The worm gear fixed shaft is axially fixed to the body at both ends via deep groove ball bearings. A worm sleeve is installed outside the worm gear fixed shaft, and the worm sleeve is connected to the worm wheel. Disc springs are installed at both ends of the worm wheel sleeve, and the disc springs are installed at both ends of the worm gear fixed shaft. One end of the worm sleeve has a worm sleeve annular groove. The eccentric crank arm component includes an eccentric shaft, and the eccentric crank arm component is installed in the worm sleeve annular groove via the eccentric shaft. A potentiometer assembly is connected to one side of the eccentric crank arm component.

[0004] In similar electric actuators, a worm sleeve is typically fitted onto the worm shaft and rotates synchronously with it. A disc spring is installed on the worm shaft, acting on the end face of the worm sleeve to limit and buffer its movement. During rotation, the axial force of the worm sleeve pushes it to move axially on the worm shaft. During this movement, the disc spring is compressed. Simultaneously, the over-torque detection rod acting on the worm sleeve is triggered, and the result is ultimately converted into output torque for display through a programmed sequence.

[0005] In the initial state, when the disc spring is installed, it will be compressed to a certain extent under the action of preload, and the worm sleeve will bear an initial elastic force value. During the rotation, the movement of the worm sleeve needs to overcome the initial elastic force value in order to move axially. That is, the output torque needs to reach a certain value in order for the worm sleeve to overcome the initial elastic force value and move axially. The value of this output torque is the minimum torque value that the over-torque device can detect.

[0006] In existing technology, when the disc spring compression is 1mm, the corresponding elastic force is 579.8N, and when the compression is 2mm, the corresponding elastic force is 1075.2N. Taking F as the elastic force applied by the disc spring to the worm gear sleeve, T as the actuator's output torque, and d as the worm wheel pitch circle diameter, the conversion formula between F and T is as follows: F = 2000 * T * 1.1 / d. Taking a 50N.m actuator as an example, the worm wheel pitch circle diameter is 90mm (the larger this value, the larger the overall size of the actuator). In existing technology, the compression of the disc spring after installation is 1.5mm, corresponding to an elastic force of 837.4N. Substituting this into the formula, the actuator output torque is 34.257Nm, which is the lowest torque that the over-torque device can detect.

[0007] When testing in a lower torque environment, the number of disc springs needs to be reduced or increased to adjust the elastic force applied by the disc springs. However, since most disc springs are standard parts, the original installation space cannot be adapted, and new molds need to be made to match different numbers of disc springs, resulting in higher production costs. Utility Model Content

[0008] To achieve low torque detection of the actuator, this application provides a low torque over-torque detection structure, which can greatly reduce the minimum torque that the over-torque device can detect.

[0009] First aspect:

[0010] The low-torque over-torque detection structure provided in this application adopts the following technical solution:

[0011] A low-torque over-torque detection structure includes a worm gear, a worm sleeve, and a mounting shaft. The mounting shaft is rotatably mounted inside an actuator. The worm sleeve is fitted onto the mounting shaft and rotates synchronously with the mounting shaft, and can slide axially along the mounting shaft. The worm gear is rotatably mounted inside the actuator and rotates synchronously with the actuator's output shaft. The worm gear meshes with the worm sleeve. Compression springs are installed at both ends of the mounting shaft. The two compression springs abut against both ends of the worm sleeve and apply elastic force to the worm sleeve. An annular groove is formed at one end of the worm sleeve, into which the detection end of the detection mechanism inside the actuator extends.

[0012] By adopting the above technical solution and customizing the compression spring according to actual needs, the preload force on the worm gear sleeve can be further reduced within the original installation space, thereby reducing the minimum torque of the trigger detection mechanism. This allows the actuator to output lower torque and remain under the effective monitoring of the over-torque device, improving the accuracy and stability of the actuator when outputting low torque. Moreover, there is no need to redesign other components of the actuator, greatly reducing production costs.

[0013] Optionally, the compression spring has a rectangular cross-section.

[0014] By adopting the above technical solution, the rectangular spring can provide a larger contact area when subjected to pressure, thereby dispersing stress and improving the spring's load-bearing capacity and stiffness. It is suitable for occasions with high loads and very limited space. When installed on the mounting shaft, it can meet the needs of high-speed compression and heavy loads.

[0015] Optionally, the mounting shaft sidewall is formed with multiple limiting protrusions, which extend axially along the mounting shaft. The inner wall of the worm gear sleeve is provided with multiple limiting grooves. The limiting protrusions and the limiting groove sidewalls mutually limit each other circumferentially along the mounting shaft. The limiting protrusions and the limiting grooves slide axially along the mounting shaft.

[0016] By adopting the above technical solution, the limiting protrusion and the limiting groove cooperate to form a circumferential limit between the mounting shaft and the worm sleeve, so as to ensure that the mounting shaft drives the worm sleeve to rotate. At the same time, the limiting protrusion can slide along the axial direction of the mounting shaft in the limiting groove to cooperate with the sliding of the worm sleeve.

[0017] Optionally, the compression spring may be a light-load spring, a medium-load spring, a heavy-load spring, or an extremely heavy-load spring.

[0018] By adopting the above technical solution, compression springs with different load-bearing capacities can be selected according to different loads or output torques to meet different over-torque detection requirements.

[0019] The second aspect:

[0020] The low-torque adjustable electric actuator provided in this application adopts the following technical solution:

[0021] A low-torque adjustable electric actuator, employing any of the aforementioned low-torque over-torque detection structures, further includes a housing and a motor. Both the low-torque over-torque detection structure and the motor are disposed inside the housing, and the output shaft of the motor is coaxially connected to the mounting shaft.

[0022] By adopting the above technical solution, by replacing the compression spring with a different spring constant in the original installation space, the minimum torque detected by the over-torque device can be adjusted without re-molding, thereby meeting the demand for low torque output; in addition, thanks to the more linear elastic force change of the compression spring, multi-level adjustment of over-torque detection can be achieved, thereby adapting to more complex needs.

[0023] Optionally, a mounting portion is formed inside the housing, the mounting shaft passes through the mounting portion, and a fixing ring is rotatably provided at both ends of the mounting shaft. The fixing ring is fixed to the mounting portion, and one end of the compression spring abuts against the worm gear sleeve, and the other end abuts against the fixing ring.

[0024] By adopting the above technical solution, while using the fixing ring to install and fix the mounting shaft, a space for accommodating the compression spring is formed between the worm sleeve and the fixing ring. The installation structure is compact and the space utilization rate is high.

[0025] Optionally, the fixing ring includes an insertion part and an abutment part. The insertion part is connected to one side of the abutment part and is inserted into the mounting part. The cross-sectional dimension of the abutment part is larger than that of the insertion part, and the abutment part abuts against the mounting part.

[0026] By adopting the above technical solution, the assembly structure of the mounting shaft is further optimized by utilizing the insertion and mating of the insertion part and the mounting part, thereby improving assembly efficiency and accuracy.

[0027] Optionally, a plurality of connecting portions are formed around the abutment portion, and each connecting portion is provided with a bolt, which is screwed into the mounting portion. The plurality of connecting portions are evenly distributed around the abutment portion.

[0028] By adopting the above technical solutions, the stability of the mounting shaft assembly structure has been further improved.

[0029] In summary, this application includes at least one of the following beneficial technical effects:

[0030] 1. By customizing compression springs according to actual needs, the preload on the worm gear sleeve can be further reduced within the original installation space, thereby reducing the minimum torque of the trigger detection mechanism. This allows the actuator to output torque at a lower level and remain under the effective monitoring of the over-torque device, improving the accuracy and stability of the actuator when outputting torque at low levels. Moreover, there is no need to redesign other parts of the actuator, which greatly reduces production costs.

[0031] 2. Rectangular springs can provide a larger contact area when under pressure, thereby dispersing stress and improving the spring's load-bearing capacity and stiffness. They are suitable for applications with high loads and very limited space. When mounted on a shaft, they can meet the requirements of high-speed compression and heavy loads.

[0032] 3. Compression springs with different load-bearing capacities can be selected according to different loads or output torques to meet different over-torque detection requirements. Attached Figure Description

[0033] Figure 1 This is a cross-sectional view of the overall structure of an embodiment of this application;

[0034] Figure 2 This is a cross-sectional view of the mounting shaft and worm gear sleeve in an embodiment of this application;

[0035] Figure 3 This is a schematic diagram showing the fixing ring separately in an embodiment of this application.

[0036] Reference numerals: 1. Housing; 11. Mounting part; 2. Motor; 3. Worm gear; 4. Worm sleeve; 41. Annular groove; 42. Limiting groove; 5. Mounting shaft; 51. Limiting protrusion; 6. Fixing ring; 61. Insertion part; 62. Abutment part; 63. Connecting part; 7. Elastic element; 71. Compression spring; 8. Detection mechanism; 9. Bearing. Detailed Implementation

[0037] The following is combined with Figure 1-3 This application is described in further detail.

[0038] This application discloses a low-torque over-torque detection structure, referring to... Figure 1 The actuator includes a worm gear 3, a worm sleeve 4, and a mounting shaft 5. The mounting shaft 5 is rotatably disposed inside the actuator and is coaxially connected to the output shaft of the drive component. The worm sleeve 4 is sleeved on the mounting shaft 5 and rotates synchronously with the mounting shaft 5. The worm gear 3 is rotatably disposed inside the actuator and meshes with the outer wall of the worm sleeve 4. The worm gear 3 is coaxially connected to the output shaft of the actuator. The drive component drives the output shaft of the actuator to rotate through the meshing of the worm gear 3 and the worm sleeve 4.

[0039] Meanwhile, the worm sleeve 4 can slide back and forth along the axial direction of the mounting shaft 5. The mounting shaft 5 is fitted with fixing rings 6 at both ends. The fixing rings 6 are installed inside the actuator. The mounting shaft 5 and the fixing rings 6 are rotatably engaged. Elastic elements 7 are provided at the positions of the mounting shaft 5 between the worm sleeve 4 and the two fixing rings 6. The elastic elements 7 are fitted on the mounting shaft 5. The two ends of the elastic elements 7 abut against the worm sleeve 4 and the fixing rings 6 respectively, and apply tension between the worm sleeve 4 and the fixing rings 6 to achieve pre-tightening of the worm sleeve 4.

[0040] In addition, one end of the worm sleeve 4 is provided with an annular groove 41, and a detection mechanism 8 is provided inside the actuator. The detection mechanism 8 has a detection end that extends into the annular groove 41. The detection mechanism 8 is used to detect the displacement of the worm sleeve 4 along the axial direction of the mounting shaft 5. The detection mechanism 8 works with the CPU to convert the displacement parameter of the worm sleeve 4 into a torque parameter, thereby realizing the over-torque detection of the actuator.

[0041] Specifically, refer to Figure 1 The elastic element 7 includes a compression spring 71, which has a helical structure and can withstand pressure along the axial direction. Two fixing rings 6 apply pressure to the compression spring 71 from both ends of the mounting shaft 5, and the two compression springs 71 apply elastic force from both ends of the worm sleeve 4, thereby providing preload to the worm sleeve 4. Compared with disc springs, springs have more controllable dimensions. By customizing compression springs 71 with different sizes and spring constants, the preload of the worm sleeve 4 can be adjusted without re-molding, thus meeting the different over-torque detection requirements of the actuator.

[0042] Furthermore, refer to Figure 1The compression spring 71 is a rectangular cross-section spring. Due to its cross-sectional characteristics, a rectangular spring can provide a larger contact area when subjected to pressure, thereby dispersing stress and improving the spring's load-bearing capacity and stiffness. It is suitable for applications with high loads and very limited space. Mounted on the mounting shaft 5, it can meet the requirements of high-speed compression and ultra-heavy loads. In addition, the compression spring 71 can be a light-load spring, a medium-load spring, a heavy-load spring, or an ultra-heavy-load spring, depending on the load conditions, to match the over-torque detection requirements under different loads or output torques.

[0043] In this embodiment, the customized compression spring 71 has an outer diameter of 30mm, an inner diameter of 15mm, a length of 21mm, and a spring constant of 118.6N / mm. After installation, the compression is 2mm, corresponding to a spring force F = 118.6 * 2 = 237.2N. Substituting this into the aforementioned conversion formula F = 2000 * T * 1.1 / d, we get T = 9.7Nm. Compared to a disc spring, this significantly reduces the minimum torque detectable by the over-torque device, allowing the actuator to output less torque while remaining under the effective monitoring of the over-torque device. Referring to the table below, which shows the actual torque values ​​of the customized spring triggering the over-torque switch under different output ratios in two directions, the error is approximately 1-2N.m, achieving over-torque adjustment in 5N.m increments.

[0044]

[0045] Reference Figure 2 The outer wall of the mounting shaft 5 is formed with multiple limiting protrusions 51, which extend axially along the mounting shaft 5. The inner wall of the worm sleeve 4 has corresponding limiting grooves 42, each corresponding to a limiting protrusion. The limiting grooves 42 extend axially along the worm sleeve 4, and their cross-sectional shape and dimensions are adapted to the cross-sectional shape and dimensions of the limiting protrusions 51. When the worm sleeve 4 is fitted onto the mounting shaft 5, each limiting protrusion 51 is located within its respective limiting groove 42. The cooperation of the limiting protrusions 51 and the limiting grooves 42 creates circumferential limiting between the mounting shaft 5 and the worm sleeve 4, ensuring that the mounting shaft 5 drives the worm sleeve 4 to rotate. Simultaneously, the limiting protrusions 51 can slide axially along the mounting shaft 5 within the limiting grooves 42 to accommodate the sliding of the worm sleeve 4.

[0046] In this embodiment, three limiting protrusions 51 are provided and are evenly distributed around the mounting shaft 5, and three corresponding limiting grooves 42 are provided.

[0047] The implementation principle of a low-torque over-torque detection structure disclosed in this application is as follows:

[0048] When the output bearing 9 of the actuator is subjected to different loads, the axial force applied by the worm wheel 3 to the worm sleeve 4 is different. The higher the load, the greater the axial force on the worm sleeve 4, and the greater the displacement of the worm sleeve 4 along the mounting shaft 5, which in turn cooperates with the detection mechanism 8 to perform over-torque detection.

[0049] By customizing the compression spring 71 according to actual needs, the preload force on the worm sleeve 4 can be further reduced within the original installation space, thereby reducing the minimum torque of the trigger detection mechanism 8. This allows the actuator to output lower torque and remain under the effective monitoring of the over-torque device, improving the accuracy and stability of the actuator when outputting low torque.

[0050] This application also discloses a low-torque adjustable electric actuator, including the aforementioned low-torque over-torque detection structure, a housing 1, and a motor 2. A mounting portion 11 is formed within the housing 1, and a mounting shaft 5 passes through the mounting portion 11. The motor 2 is mounted inside the housing 1, and the output shaft of the motor 2 is coaxially connected to the mounting shaft 5. Two retaining rings 6 are respectively fitted onto both ends of the mounting shaft 5 and fixed to the mounting portion 11. The mounting shaft 5 and the retaining rings 6 are rotatably connected via bearings 9. The inner ring of the bearing 9 is fitted onto the mounting shaft 5, and the outer ring of the bearing 9 is embedded in the retaining rings 6. In this embodiment, a deep groove ball bearing 9 is selected.

[0051] Specifically, refer to Figure 3 The fixing ring 6 includes an insertion portion 61 and an abutment portion 62, both of which are cylindrical. One end of the insertion portion 61 is formed at one end of the abutment portion 62, and the diameter of the abutment portion 62 is larger than the diameter of the insertion portion 61. The insertion portion 61 is inserted into the mounting portion 11, and when the insertion portion 61 is inserted into the mounting portion 11, the abutment portion 62 abuts against the mounting portion 11. At the same time, a plurality of connecting portions 63 are formed around the abutment portion 62, and each connecting portion 63 is provided with a bolt. The bolt is screwed into the mounting portion 11 to fix the fixing ring 6 as a whole to the mounting portion 11.

[0052] In this embodiment, three connecting portions 63 are provided and evenly distributed around the circumference of the insertion portion 61. The triangular distribution of the mounting structure further ensures the stability of the fixing ring 6 during installation.

[0053] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A low-torque over-torque detection structure, characterized in that: The actuator includes a worm gear (3), a worm sleeve (4), and a mounting shaft (5). The mounting shaft (5) is rotatably mounted inside the actuator. The worm sleeve (4) is fitted onto the mounting shaft (5). The worm sleeve (4) rotates synchronously with the mounting shaft (5) and can slide along the axial direction of the mounting shaft (5). The worm gear (3) is rotatably mounted inside the actuator and rotates synchronously with the actuator output shaft. The worm gear (3) meshes with the worm sleeve (4). Compression springs (71) are installed at both ends of the mounting shaft (5). The two compression springs (71) abut against both ends of the worm sleeve (4) and apply elastic force to the worm sleeve (4). An annular groove (41) is provided at one end of the worm sleeve (4). The annular groove (41) allows the detection end of the detection mechanism (8) inside the actuator to extend into it.

2. The low-torque over-torque detection structure according to claim 1, characterized in that: The compression spring (71) has a rectangular cross-section.

3. The low-torque over-torque detection structure according to claim 1, characterized in that: The mounting shaft (5) has multiple limiting protrusions (51) formed on its side wall. The limiting protrusions (51) extend axially along the mounting shaft (5). The inner wall of the worm sleeve (4) is provided with multiple limiting grooves (42). The side walls of the limiting protrusions (51) and the limiting grooves (42) limit each other circumferentially along the mounting shaft (5). The limiting protrusions (51) and the limiting grooves (42) slide axially along the mounting shaft (5).

4. The low-torque over-torque detection structure according to claim 1, characterized in that: The compression spring (71) is a light-load spring, a medium-load spring, a heavy-load spring, or an extremely heavy-load spring.

5. A low-torque adjustable electric actuator, employing the low-torque over-torque detection structure described in any one of claims 1-4, characterized in that: It also includes a housing (1) and a motor (2). The low torque over-torque detection structure and the motor (2) are both located inside the housing (1). The output shaft of the motor (2) is coaxially connected to the mounting shaft (5).

6. A low-torque adjustable electric actuator according to claim 5, characterized in that: An installation part (11) is formed inside the housing (1). The installation shaft (5) passes through the installation part (11). Fixed rings (6) are rotatably provided at both ends of the installation shaft (5). The fixed rings (6) are fixed to the installation part (11). One end of the compression spring (71) abuts against the worm sleeve (4), and the other end abuts against the fixed ring (6).

7. A low-torque adjustable electric actuator according to claim 6, characterized in that: The fixing ring (6) includes a plug-in part (61) and an abutment part (62). The plug-in part (61) is connected to one side of the abutment part (62). The plug-in part (61) is plugged into the mounting part (11). The cross-sectional dimension of the abutment part (62) is larger than that of the plug-in part (61). The abutment part (62) abuts against the mounting part (11).

8. A low-torque adjustable electric actuator according to claim 7, characterized in that: The abutment portion (62) has a plurality of connecting portions (63) formed around its periphery. Each connecting portion (63) is provided with a bolt, which is screwed into the mounting portion (11). The plurality of connecting portions (63) are evenly distributed around the abutment portion (62).

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