Self-locking transmission structure with friction clutch device

Abstract

This application belongs to the field of clutch structure technology, specifically providing a self-locking transmission structure with a friction clutch device. The self-locking transmission mechanism is a reduction transmission mechanism with self-locking characteristics. Its input end is connected to a motor, and its output end is fixedly connected to an output shaft, which is connected to an actuator. A friction clutch mechanism is provided between the output end of the self-locking transmission mechanism and the actuator. The friction clutch mechanism includes a positive pressure providing device and at least one friction transmission component. The friction transmission component is disposed between the end face of the output shaft and the actuator. The positive pressure providing device provides positive pressure to the friction working surface of the friction transmission component. Even with the transmission structure self-locked, the output end can still be manually rotated. When a large external torque is applied to the actuator, slippage only occurs at the friction surface, effectively protecting the self-locking transmission structure and the motor from damage. The technical principle and clutch position design of this application are universally applicable to all transmission mechanisms with self-locking characteristics and output rotational motion.

Description

Technical Field

[0001] This application belongs to the field of clutch structure technology, specifically providing a self-locking transmission structure with a friction clutch device. Background Technology

[0002] Among various driving devices, some transmission mechanisms naturally possess self-locking characteristics due to their structural features. That is, when the input end stops driving, the output end cannot reverse drive the input end under the action of external force, and the output end is locked in the current position without the need for an additional braking device. Transmission mechanisms with self-locking characteristics mainly include the following categories: (1) Worm gear transmission, due to its large lead angle helical pair characteristics, self-locking occurs when the worm lead angle is less than the equivalent friction angle of the meshing surface. It is the most common form of self-locking transmission and is widely used in various speed reduction drive devices. (2) Cycloidal pinwheel reducer, which can possess self-locking characteristics under a specific combination of transmission ratio and friction coefficient, and is widely used in precision applications such as robot joints due to its high rigidity and high precision. (3) Planetary gear reducer with few tooth difference, when the tooth difference, pressure angle and friction coefficient satisfy a specific relationship, the output end also cannot reverse drive the input end, thus possessing self-locking characteristics.

[0003] The aforementioned transmission mechanisms with self-locking characteristics face a common problem in certain application scenarios: when the equipment is powered off and the input end stops rotating, external forces (such as manual adjustment by the operator, elastic restoring force of the driven mechanism, etc.) cannot make the output end rotate and reset, requiring the input end to be re-driven before the position can be adjusted, which is inconvenient to operate.

[0004] Existing solutions mainly fall into two categories: The first category is a rigid clutch mechanism, which actively disengages the rigid connection within the transmission mechanism, allowing the output shaft to rotate freely. This type of solution requires active control of the disengagement / engagement action, has a complex structure, and the output shaft is unrestrained in the disengaged state, making it impossible to achieve a smooth transition between normal transmission and manual rotation simultaneously; the keyway / spline connection also introduces backlash, affecting transmission accuracy. The second category is a physical disengagement solution for the transmission components, which achieves physical disengagement by shifting the input component relative to the output component. This also requires active operation and has a complex structure.

[0005] On the other hand, the existing technology of setting a friction clutch mechanism inside the reducer (such as between the worm gear and the output shaft) is mainly used for overload protection. Its clutch position is inside the transmission chain. Even after the external torque exceeds the threshold, it will still act on the transmission chain, causing the transmission components and motor to bear unnecessary impact loads. Such solutions do not consider friction surface wear compensation, and the clutch function will fail due to wear after long-term use.

[0006] In summary, existing technologies have significant shortcomings in resolving the contradiction between transmission mechanisms with self-locking characteristics and the convenience of manual operation at the output end. It is necessary to provide a new solution that can be universally applied to various self-locking transmission mechanisms. Summary of the Invention

[0007] To address the technical problem of the contradiction between a self-locking transmission mechanism and the ease of manual operation at the output end, this application places the friction clutch mechanism outside the output end of the self-locking transmission chain, specifically between the output shaft end face and the actuator, rather than inside the transmission chain. During normal operation, the input end drives the transmission mechanism, and the output shaft rotates the actuator via friction. When an external torque exceeding the friction limit is applied to the actuator, the actuator slides relative to the output shaft, and the external torque acts only on the clutch friction surface, not transmitted to the transmission chain. The self-locking characteristic of the transmission chain ensures that external torque will not reverse-drive the input end, thus protecting the motor.

[0008] First, this application provides a self-locking transmission structure with a friction clutch device. The self-locking transmission mechanism is a reduction transmission mechanism with self-locking characteristics. Its input end is connected to a motor, and its output end is fixedly connected to an output shaft. The output shaft is connected to an actuator. A friction clutch mechanism is also provided between the output end of the self-locking transmission mechanism and the actuator. The friction clutch mechanism includes a positive pressure providing device and at least one friction transmission component. The at least one friction transmission component is disposed between the end face of the output shaft and the actuator. The end face of the output shaft, the at least one friction transmission component, and the actuator are in sequential contact with each other along the axial direction. At least one surface of the at least one friction transmission component forms a friction working surface with the adjacent component. The positive pressure providing device provides continuous positive pressure to the friction transmission component along the normal direction of the friction working surface, so that the friction transmission component is pressed against the adjacent component at the friction working surface.

[0009] In some embodiments, when only one friction drive is provided, one side of the friction drive is fixedly connected to either the output shaft end face or the actuator, and the other side of the friction drive is rotatably in contact with either the output shaft end face or the actuator. The surface of the friction drive that is rotatably in contact with the output shaft end face or the actuator forms a friction working surface.

[0010] In some embodiments, when the number of friction transmission components is greater than 1, multiple friction transmission components are connected in series to form a transmission chain. The friction transmission components at both ends of the transmission chain are fixedly connected to the output shaft and the actuator, respectively. Two adjacent friction transmission components in the transmission chain can rotate relative to each other and form a friction working surface.

[0011] In some embodiments, the positive pressure providing device provides a positive pressure F to the contact surface between the friction drive element and the output shaft end face or the actuator, satisfying the following conditions: T1<μ0F <T2……(1) T1≤ μF……(2) Where T1 is the minimum torque required to drive the actuator, T2 is the maximum torque that the output end can withstand when the transmission mechanism does not fail, μ0 is the maximum static friction coefficient between the friction transmission component and its non-fixed surface, and μ is the dynamic friction coefficient between the friction transmission component and its non-fixed surface.

[0012] In some embodiments, the friction drive is a friction plate, which is fixedly connected to either the output shaft end face or the actuator by adhesive or screws.

[0013] In some embodiments, the positive pressure providing device includes a fastener and a pressure member. One end of the fastener is fixedly connected to the output shaft. The pressure member generates elastic force under pressure. The elastic force is transmitted to the friction working surface through the contact surface between the positive pressure providing device and the actuator and / or friction transmission member.

[0014] In some embodiments, the pressure element is an elastic element that provides a floating stroke along the positive pressure direction, and the component of the elastic force of the elastic element at different compression positions in the normal direction of the friction surface is the positive pressure F.

[0015] In some embodiments, the elastic element is at least two disc springs, with adjacent disc springs mounted opposite each other along the positive pressure direction.

[0016] In some embodiments, the fastener is a stopcock, the end face of the output shaft is provided with a threaded hole, the threaded section of the stopcock passes through the through hole of the actuator and is screwed into the threaded hole, and the elastic element is sleeved around the smooth section of the stopcock.

[0017] In some embodiments, a friction-reducing element is provided between the contact surfaces of the positive pressure providing device and other components, the friction-reducing element being used to reduce the frictional torque when the positive pressure providing device and the actuator rotate relative to each other.

[0018] Compared with the prior art, the beneficial effects that this application can achieve are: 1. With the transmission structure self-locking, the output end can still be rotated manually without the need for power, making it convenient to use.

[0019] 2. When a large external torque is applied to the actuator, slippage only occurs at the friction surface. The torque applied to the self-locking transmission structure has a clear upper limit, effectively protecting the self-locking transmission structure and the motor from damage.

[0020] 3. The transmission structure itself is self-locking, and external torque is not transmitted to the transmission structure (it only acts on the clutch friction surface), so there is no loss to the transmission structure and motor; the wear compensation mechanism of the elastic element ensures that the function is effective for a long time after frequent external force operation.

[0021] 4. Friction coupling reduces the coaxiality requirement between the output end and the actuator, avoids transmission abnormalities caused by misalignment of the lower-level mechanism, and improves assembly tolerance.

[0022] 5. The single friction surface fixed connection scheme has a very small relative sliding amount between the driving end and the driven end during transmission reversal (theoretically zero), which is suitable for precision drive applications that require low backlash.

[0023] 6. The technical principles and clutch position design of this solution are universally applicable to all transmission mechanisms with self-locking characteristics and output rotational motion, and are not limited to worm gears, thus having a wide range of applications.

[0024] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 A schematic diagram of the self-locking transmission structure with friction clutch device in this application is shown; Figure 2 A schematic diagram of another self-locking transmission structure with a friction clutch device is shown in this application; Figure 3 A schematic diagram of another self-locking transmission structure with a friction clutch device is shown in this application; Figure 4 An assembly schematic diagram of the self-locking transmission structure with friction clutch device in this application is shown; In the diagram: 100-worm gear, 101-motor, 1012-circular locating boss, 1042-synchronous belt, 1044-bearing housing; 200-helical gear, 201-output shaft, 2011-first step surface, 2012-second step surface, 2021-upper bearing inner ring, 2031-lower bearing inner ring, 2022-upper bearing outer ring, 2032-lower bearing outer ring, 2041-external thread, 2013-fifth step surface, 204-throat circle, 205-adjusting shim; 3011-slender hole, 3013-third step. Step surface, 3023-fourth platform, 303-first bolt; 401-fourth bolt, 402-anti-loosening washer, 404-hinge, 407-guide rail, 406-slider; 501-actuator, 502-friction plate, 503-disc spring, 504-flat thrust bearing, 505-plug screw, 5021-second bolt, 5031-wave washer, 5051-shaft end plate, 5052-third bolt, 5011-corresponding surface, 5041-waist; 605-eccentric wheel; 700-base, 701-edge. Detailed Implementation

[0027] The term "comprising" in this application specification is synonymous with "including," "containing," or "characterized in," and is inclusive or open-ended, and does not exclude additional undescribed elements or method steps.

[0028] It should be noted that similar reference numerals and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, the terms "first," "second," "third," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance. The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0029] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0030] To achieve overload protection, existing transmission mechanisms with self-locking characteristics typically place the friction clutch inside the transmission chain (e.g., between the worm gear and the output shaft). However, when the external torque exceeds the clutch threshold, although relative slippage occurs between the worm gear and the output shaft, the external torque has already passed the output shaft before reaching the clutch surface. Therefore, the output shaft and its bearings still bear the full external torque. Furthermore, on the transmission chain side of the clutch surface, since the worm gear is still meshing with the worm, the vibration and impact loads caused by clutch slippage are transmitted to the motor via the worm gear-worm meshing surface.

[0031] This application provides a self-locking transmission structure with a friction clutch device. The self-locking transmission mechanism is a reduction transmission mechanism with self-locking characteristics. Its input end is connected to a motor 101, and its output end is fixedly connected to an output shaft 201. The output shaft 201 is connected to an actuator 501. A friction clutch mechanism is also provided between the output end of the self-locking transmission mechanism and the actuator 501. The friction clutch mechanism includes a positive pressure providing device and at least one friction transmission component. The at least one friction transmission component is disposed between the end face of the output shaft 201 and the actuator 501. The end face of the output shaft 201, the at least one friction transmission component, and the actuator 501 are in sequential contact with each other along the axial direction. At least one surface of the at least one friction transmission component forms a friction working surface with an adjacent component. The positive pressure providing device provides continuous positive pressure to the friction transmission component along the normal direction of the friction working surface, so that the friction transmission component is pressed against the adjacent component at the friction working surface.

[0032] This application positions the friction clutch mechanism at a specific location between the end face of the output shaft 201 of the self-locking drive chain and the external actuator 501, rather than inside the drive chain (e.g., between the worm gear and the output shaft 201). The self-locking drive chain itself acts as a rigid support for the friction clutch surface. When the actuator 501 is subjected to external torque, the force transmission path is: external torque → actuator 501 → friction clutch surface. Since the friction clutch surface is located at the very end of the drive chain's output, if the external torque exceeds the maximum static friction torque after reaching the friction clutch surface, the actuator 501 will slide relative to the end face of the output shaft 201. This prevents the external torque from reaching the drive chain, thus preventing all components in the drive chain (gears, bearings, motor 101) from experiencing external torque exceeding the maximum static friction force of the contact surface. The torque is confined to the friction surface and does not enter the drive chain. This achieves complete protection for the drive chain and motor 101, and completely isolates the external torque.

[0033] Meanwhile, the self-locking characteristic of the transmission mechanism prevents the output shaft 201 from rotating in the reverse direction under external torque. Because the output end is locked at the current angular position by the self-locking transmission chain, one side of the friction clutch surface (the end face of the output shaft 201) forms a fixed friction support surface, allowing the actuator 501 to slide relative to this fixed surface. If the transmission mechanism did not possess the self-locking characteristic, the external torque would drive the gears in the transmission chain and the input motor 101 in the reverse direction through the output shaft 201. Even with the friction clutch mechanism, the external torque would still be transmitted along the transmission chain, and the force isolation function of the friction clutch mechanism would fail. Therefore, the technical effect achieved in this application is the result of the synergistic effect of the self-locking characteristic and the clutch position, and cannot be achieved by simply changing the clutch position or solely utilizing the self-locking characteristic.

[0034] The "transmission mechanism with self-locking characteristics" referred to in this application means a transmission mechanism in which, within the normal operating load range, when the input end stops driving, the output end will not reverse drive the input end under the action of external torque. Specifically, the transmission mechanism can be a worm gear 100 transmission mechanism (the worm 100 is the input end, and the worm wheel or a helical gear 200 directly meshing with the worm 100 is the output end), a cycloidal pinwheel reducer, a planetary gear reducer with a small tooth difference, or other rotary output transmission mechanisms with self-locking characteristics. An intermediate transmission stage (helical gear 200, bevel gear, double gear, etc.) can be set between the input end and the output end as needed to achieve the required reduction ratio.

[0035] The term "actuator 501" as used in this application refers to a component connected to the output shaft 201 of the transmission mechanism via a friction clutch mechanism, used to transmit rotational motion to a lower-level mechanism or load. The actuator 501 may be a rotating arm, output flange, gear, cam, pulley, or other component capable of receiving rotational motion and transmitting it to the driven object. This application does not limit the specific form and use of the actuator 501.

[0036] The term "friction working surface" as used in this application refers to the surface of a friction transmission component that, under normal pressure, contacts adjacent components (the end face of the output shaft 201, the actuator 501, or adjacent friction transmission components) and transmits or limits torque through friction. During normal transmission, the friction working surface is in a static friction state to transmit torque, with the components on both sides maintaining static friction contact and no relative sliding occurring. The output shaft 201 transmits torque to the actuator 501 through the friction working surface, and the actuator 501 rotates synchronously with the output shaft 201. When the external torque exceeds the maximum static friction torque, it switches to a dynamic friction state to achieve clutch protection.

[0037] The term "output shaft 201 end face" as used in this application refers to the surface of the output shaft 201 at its axial end, including the shaft end plane, the stepped surface provided at the shaft end, the flange surface provided at the shaft end, and other surfaces that can form axial positive pressure contact with the friction transmission component.

[0038] The term "positive pressure providing device" as used in this application refers to a device or structure capable of providing continuous positive pressure to a friction transmission component along the normal direction of the friction working surface. The positive pressure providing device can provide positive pressure through mechanical elastic elements (disc spring 503, wave washer 5031, coil spring, spring nut, etc.), magnetic elements, pneumatic elements, or combinations thereof. This application uses a mechanical elastic element as an example in its embodiments, but is not limited thereto.

[0039] In some embodiments, when only one friction drive is provided, one side of the friction drive is fixedly connected to either the end face of the output shaft 201 or the actuator 501, and the other side of the friction drive is rotatably in contact with either the end face of the output shaft 201 or the actuator 501. The surface of the friction drive that is rotatably in contact with the end face of the output shaft 201 or the actuator 501 forms a friction working surface.

[0040] In the single friction plate 502 scheme, the friction plate 502 is fixed on one side and slides on the other side, with only one friction working surface. It has a compact structure, small axial dimension, and extremely small relative sliding amount between the active and passive ends during reversal. It is suitable for occasions with strict requirements on space and backlash.

[0041] In some embodiments, when the number of friction transmission components is greater than 1, multiple friction transmission components are connected in series to form a transmission chain. The friction transmission components at both ends of the transmission chain are fixedly connected to the output shaft 201 and the actuator 501, respectively. Two adjacent friction transmission components in the transmission chain can rotate relative to each other and form a friction working surface.

[0042] In the dual friction plate 502 scheme, the two plates are respectively fixed to the output shaft 201 and the actuator 501. The contact surface of the two is the friction working surface. Both friction plates 502 can be disassembled and installed by bolts. They can be replaced individually after wear. The maintenance cost is low and it is suitable for occasions where the friction surface wears frequently and requires regular maintenance.

[0043] In some embodiments, the positive pressure providing device provides a positive pressure F to the contact surface between the friction drive and the end face of the output shaft 201 or the actuator 501, satisfying the following conditions: T1<μ0F <T2……(1) T1≤ μF……(2) Where T1 is the minimum torque required to drive the actuator 501, T2 is the maximum torque that the output end can withstand when the transmission mechanism does not fail, μ0 is the maximum static friction coefficient between the friction transmission component and its non-fixed surface, and μ is the dynamic friction coefficient between the friction transmission component and its non-fixed surface.

[0044] In formula (1), T1 < μ0F ensures that during normal operation, the maximum static friction torque between the friction drive member and the end face of the output shaft 201 is greater than the minimum torque required to drive the actuator 501, enabling the output shaft 201 to reliably drive the actuator 501 to rotate through static friction without slipping; μ0F < T2 ensures that when an external torque acts on the friction surface through the actuator 501, the maximum torque that the friction surface can transmit does not exceed the safety bearing threshold at the output end of the transmission mechanism, thereby causing slip protection at the friction surface rather than failure of the transmission mechanism.

[0045] In formula (2), T1 ≤ μF is for the case of active commutation: when the driving direction at the input end changes, there may be a brief relative rotation between the output shaft 201 and the actuator 501. At this time, the friction surface is in a dynamic friction state. Formula (2) ensures that the dynamic friction torque is still not less than the minimum torque required to drive the actuator 501, reducing the risk that the actuator 501 loses its following ability during the commutation process.

[0046] In some embodiments, the friction drive member is a friction plate 502, and the friction drive member is fixedly connected to either the end face of the output shaft 201 or the actuator 501 by gluing or screws.

[0047] In some embodiments, the normal pressure providing device includes a fastener and a pressure member. One end of the fastener is fixedly connected to the output shaft 201, and the pressure member generates an elastic force under a compressed state. The elastic force is transmitted to the friction working surface through the contact surface between the normal pressure providing device and the actuator 501 and / or the friction drive member.

[0048] In some embodiments, the pressure member is an elastic element, which provides a floating stroke along the normal pressure direction, and the component of the elastic force of the elastic element at different compression amounts in the normal direction of the friction surface is the normal pressure F.

[0049] As used in this application, the "floating stroke" refers to the effective elastic deformation range of the elastic element in the normal pressure direction. Within this stroke range, the elastic force of the elastic element can always provide a normal pressure that meets the constraints for the friction working surface. The existence of the floating stroke enables the elastic element's compression amount to decrease correspondingly after the friction working surface wears and its axial dimension decreases, but it still remains within the effective stroke range, and the normal pressure will not drop to the failure level, thereby achieving automatic compensation for wear.

[0050] In some embodiments, the elastic element is at least two disc springs 503, and two adjacent disc springs 503 are installed in an opposing manner along the normal pressure direction.

[0051] The elastic element adopts a combined manner of at least two disc springs 503 in an opposing combination. Two adjacent disc springs 503 are installed with their small - end faces facing each other or their large - end faces facing each other (hereinafter collectively referred to as "opposing").

[0052] In one embodiment, the elastic element is two disc springs 503, which are installed facing each other with their small ends facing each other (arranged along the axial direction as: large-small-small-large).

[0053] In another embodiment, the elastic element consists of three disc springs 503 arranged sequentially along the positive pressure direction, with the first and second disc springs facing each other at their small ends, and the second and third disc springs facing each other at their large ends (arranged in the axial direction as follows: large-small-small-large-large-small).

[0054] The force-deformation characteristic curve of disc spring 503 is non-linear, and a single disc spring 503 reaches a large stiffness range within a small deformation range. When two or more disc springs 503 are used in a mating installation, the overall deformation is several times that of a single spring, while the load is the same. This means that during the process of wear on the friction surface and reduction in the compression of the disc spring 503, the change in normal pressure under the mating installation method is significantly smaller than that under the single spring or unidirectional installation method. This keeps the transmission friction torque of the friction surface within the constraint range throughout the entire wear compensation stroke, reducing the probability of premature failure due to a sudden drop in normal pressure caused by wear, or excessive manual rotation resistance due to high normal pressure.

[0055] Those skilled in the art can select the appropriate number of disc springs 503 and combine them in the above-described pairing manner according to the required wear compensation stroke. It should be noted that if two adjacent disc springs 503 are stacked in the same direction (i.e., the small end and the large end face each other, and the axial arrangement is "large-small-large-small"), then the stiffness of multiple disc springs 503 is superimposed rather than the deformation is superimposed. The overall result is that the stiffness increases while the deformation remains unchanged, which cannot achieve the technical purpose of expanding the wear compensation stroke. Therefore, it is not within the scope of protection of this application.

[0056] In some embodiments, the fastener is a screw 505, the end face of the output shaft 201 is provided with a threaded hole, the threaded section of the screw 505 passes through the through hole of the actuator 501 and is screwed into the threaded hole, and the disc spring 503 is sleeved around the smooth section of the screw 505.

[0057] In this embodiment, the fastener selected is a 505 threaded screw. The 505 threaded screw has three sections: a threaded section, a smooth section, and a head. These three sections perform different technical functions in this solution.

[0058] After passing through the through hole of the actuator, the threaded section is screwed into the threaded hole on the end face of the output shaft 201, thus anchoring the entire positive pressure providing device onto the output shaft 201. The preload of the threaded connection can be set by controlling the tightening torque, thereby indirectly controlling the initial compression and initial positive pressure value of the disc spring 503.

[0059] The smooth section is located between the threaded section and the head. Its outer diameter is precisely machined, and its surface is smooth and thread-free. The disc spring 503 is fitted around the smooth section, using the outer surface of the smooth section as a radial positioning reference, ensuring that the disc spring 503 and the threaded hole of the output shaft 201 remain coaxial. This coaxial positioning ensures that the spring force of the disc spring 503 is transmitted along the axis of the output shaft 201, and the normal pressure is evenly applied to the friction working surface, reducing uneven wear on the friction working surface caused by eccentric loads. Simultaneously, the smooth section surface is thread-free, allowing the disc spring 503 and the friction-reducing component to slide freely along the axial direction of the smooth section without being jammed by threads, ensuring unimpeded axial movement of the disc spring 503 during wear compensation.

[0060] The head diameter is larger than the polished rod diameter, forming a stepped surface between them. After the screw is tightened to the correct position, the head stepped surface transmits the positive pressure to the actuator 501 through the disc spring 503. During the process of the actuator 501 moving upward axially due to friction surface wear, the compression of the disc spring 503 decreases. However, as long as the axial displacement of the actuator 501 does not exceed the axial length of the polished rod, the disc spring 503 is always constrained between the head stepped surface and the actuator 501, and the overall assembly relationship of the positive pressure providing device remains unchanged.

[0061] In one embodiment, the friction transmission component is an annular friction plate 502 with a through hole at its center. The threaded section of the plug screw 505 passes through the through hole of the actuator 501 and the central through hole of the friction plate 502 in sequence and is then screwed into the threaded hole on the end face of the output shaft 201. The inner diameter of the central through hole of the friction plate 502 is larger than the outer diameter of the smooth section of the plug screw 505, so that the actuator 501 and the friction plate 502 can rotate around the plug screw 505.

[0062] In another embodiment, the friction drive is a friction disc or friction ring without a central through hole, which is bonded to the end face of the actuator 501. The path of the plug screw 505 does not pass through the friction drive, and the friction working surface of the friction drive contacts the end face of the output shaft 201 in the annular area around the plug screw 505.

[0063] In some embodiments, a friction-reducing element is provided between the contact surfaces of the positive pressure providing device and other components. The friction-reducing element is used to reduce the frictional torque when the positive pressure providing device and the actuator 501 rotate relative to each other.

[0064] The term "friction-reducing component" as used in this application refers to a component disposed between the positive pressure providing device and its adjacent rotating component to reduce the coefficient of friction between their contact surfaces. The friction-reducing component may be a planar thrust bearing 504, a needle roller thrust bearing, a self-lubricating gasket (such as a PTFE gasket, a graphite-based composite gasket), or other components capable of providing low-friction rotational support while bearing axial positive pressure.

[0065] A friction-reducing component is installed at the contact surface between the positive pressure providing device and the actuator 501. When the actuator 501 rotates relative to the output shaft 201 under external force, there is a relative rotational tendency between the elastic element in the positive pressure providing device and the actuator 501. If the two are in direct contact, the dynamic friction torque at the contact surface may cause wear and torsional deformation of the end face of the elastic element, and the positive pressure will deviate from the design value after long-term use. The installation of the friction-reducing component ensures that the aforementioned relative rotation occurs at the low-friction interface of the friction-reducing component, significantly reducing the friction torque borne by the elastic element, thereby slowing down the accumulation of wear and deformation and extending the effective service life of the friction clutch mechanism.

[0066] Furthermore, the friction drive component can be fixed to the actuator 501 instead of the output shaft 201. During normal transmission reversal, the relative sliding amount between the driving end of the output shaft 201 and the driven end of the actuator 501 is extremely small, making it suitable for low backlash precision transmission applications.

[0067] When the friction drive component is fixed to the actuator 501, the friction working surface is located between the friction drive component and the end face of the output shaft 201. During normal transmission, the output shaft 201 drives the friction drive component and the actuator 501 to rotate synchronously through static friction, with no relative motion between the three. When the input end reverses direction, due to the backlash inside the transmission chain, the output shaft 201 will have a slight angular return stroke. However, the friction drive component and the actuator 501 remain stationary as fixed bodies (held by load or inertia). The angular displacement of the end face of the output shaft 201 relative to the friction drive component is equal to the return angle inside the transmission chain. Since the static friction at the friction surface re-establishes clamping within this slight return stroke, the actual displacement of the actuator 501 can approach zero.

[0068] In contrast, if the friction drive component is fixed to the output shaft 201, the output shaft 201 will drive the friction drive component to return together during commutation, and the return angle will be directly transmitted to the actuator 501, which is detrimental to low-backlash precision transmission. The present application will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0069] Example 1 like Figure 1As shown, in this embodiment, the transmission mechanism is a worm gear transmission mechanism. The input end of the transmission mechanism is a worm 100, which is directly machined on the output shaft of the motor (not shown in the figure). The motor is provided with a threaded hole for bolt connection and a circular positioning boss 1012. The output end of the transmission mechanism is a helical gear 200 that meshes with the worm gear 100. The helical gear 200 is fixed to the output shaft 201 by riveting. The output shaft 201 is provided with a first stepped surface 2011 and a second stepped surface 2012. The first stepped surface 2011 and the first stepped surface 2012 are respectively used to abut against the inner ring 2021 of the upper bearing and the inner ring 2031 of the lower bearing. The housing 300 has mounting holes and stepped surfaces. The upper housing 302 and the lower housing 301 are respectively provided with a third stepped surface 3013 and a fourth stepped surface 3023. The third stepped surface 3013 and the fourth stepped surface 3023 are respectively used to abut against the outer ring 2022 of the upper bearing and the outer ring 2032 of the lower bearing. After the upper housing 302 and the lower housing 301 are fastened by the first bolt 303, the abutting surfaces are pressed together to eliminate the assembly gap caused by bearing clearance and part tolerance.

[0070] The input end of the friction clutch mechanism is the output shaft 201 of the helical gear 200, and the output end is the actuator 501. The friction transmission component is a friction plate 502, which is fixed to the inner surface of the actuator 501 by adhesive bonding, and its outer surface is in relative rotatable contact with the end face of the output shaft 201.

[0071] The positive pressure providing device includes fasteners, pressure components, and friction-reducing components. The pressure component is an elastic element. The component of the elastic force of the elastic element at different compression positions in the normal direction of the friction surface is the positive pressure F. The elastic element also provides a certain floating stroke for the positive pressure providing device along the positive pressure direction, so that the positive pressure is effective within the stroke range. It is used to compensate for the dimensional changes caused by friction surface wear and ensure that the function does not degrade after long-term use.

[0072] In this embodiment, a disc spring 503 is preferably used, whose stiffness curve is relatively flat within the working stroke, resulting in small changes in normal pressure after wear compensation. A friction-reducing component is a planar thrust bearing 504, which is fitted around the optical shaft of the fastener and held in place by the end face of the actuator, providing smooth rotational support when the actuator and output shaft rotate relative to each other. A plug screw 505 is used, with its threaded section screwed into the threaded hole of the output shaft. The disc spring and thrust bearing are fitted around the optical shaft section, making the assembly method simple and reliable. The threaded section of the plug screw 505 passes through the central through-hole of the actuator 501 and the friction plate 502 and is screwed into the threaded hole 204 of the output shaft 201. The disc spring 503 and thrust bearing 504 are fitted around the optical shaft portion of the plug screw 505. The thrust bearing 504 is held in place by the end face of the actuator 501. After the screw 505 is tightened to the designed torque, the disc spring 503 is compressed, and its elastic force is converted into a positive pressure between the friction plate 502 and the end face of the output shaft 201, enabling the output shaft 201 to drive the actuator 501 to rotate through static friction. When the actuator 501 is subjected to an external force exceeding the maximum static friction, the friction plate 502 slides relative to the end face of the output shaft. After the friction surface wears, the pressure on the disc spring decreases, and the actuator 501 moves upward. Within a certain range of wear, sufficient positive pressure is still maintained, achieving wear self-compensation.

[0073] In the single friction plate scheme, one side of the friction plate is fixed and the other side slides, with only one friction working surface. The structure is compact, the axial dimension is small, and the relative sliding amount between the active and passive ends is extremely small when reversing. It is suitable for occasions with strict requirements on space and backlash.

[0074] Example 2 The main differences between this embodiment and embodiment one are: (1) The output end of the transmission mechanism is changed to a worm gear 200 with a throat circle 204. The axial installation position of the bearing needs to be adjusted by adjusting the clearance shim 205 to ensure that the worm gear and worm are properly meshed and without interference; (2) The connection between the motor and the housing 300 is changed to a hinge 404; (3) The friction clutch mechanism is changed to a double friction plate scheme - two friction plates 502 are respectively fastened to the turbine output shaft 201 and the actuator 501 by the second bolt 5021. The contact surface of the two friction plates 502 is the friction working surface; the positive pressure providing device is changed to a wave-shaped shim 5031. After the two third bolts 5052 lock the shaft end baffle 5051 in place, the wave-shaped shim 5031 provides appropriate positive pressure to make the working surfaces of the two friction plates stick together, such as Figure 2 As shown. The two friction plates 502 are fixed together by the second bolt 5021, which facilitates the individual replacement of the friction plates after the friction surfaces are worn, making maintenance convenient.

[0075] In the dual friction plate scheme, the two plates are fixedly connected to the output shaft and the actuator respectively. The contact surface of the two is the friction working surface. Both friction plates can be disassembled and installed by bolts, and can be replaced individually after wear. The maintenance cost is low, and it is suitable for occasions where the friction surface wears frequently and requires regular maintenance.

[0076] Example 3 like Figure 3-4 As shown, the main difference between this embodiment and the previous embodiment is that: (1) the worm 100 of the transmission mechanism does not directly serve as the motor shaft. The output shaft of the motor 101 is fixedly connected to the driving synchronous pulley 1041, and the driven synchronous pulley is fixedly connected to the worm 100 on the same axis. The driving synchronous pulley 1041 and the driven synchronous pulley are connected by a synchronous belt 1042. During operation, the motor 101 rotates, driving the driving synchronous pulley 1041 to rotate. The power is transmitted to the driven synchronous pulley via the synchronous belt 1042, thereby driving the worm 100, which is coaxially arranged with the driven synchronous pulley, to rotate.

[0077] The worm 100 shaft is constrained by the bearing and the bearing seat 1044 by the shaft shoulder. The bearing seat 1044 is fixed relative to the motor 101. The scheme of this embodiment is applicable to the occasion where the motor 101 needs to be arranged in a staggered manner with the worm 100; (2) The transmission backlash elimination mechanism is changed to the guide rail 407-slider 406 scheme. The guide rail 407 is fixedly connected to the lower housing 301. The slider 406 is fixedly connected to the motor 101 and the bearing seat 1044. The motor 101 is rotatably connected to the housing 300 through the hinge 404. The housing 300 is also provided with a waist-shaped hole 3011 opened along the hinge rotation direction. The motor is connected to the housing through the fourth bolt 401 passing through the waist-shaped hole 3011. An anti-loosening washer 402 is also added between the head of the fourth bolt 401 and the housing. , so that the motor 101 drives the worm 100 to rotate around the hinge axis to the backlash elimination position, thereby realizing linear movement backlash elimination; (3) The helical gear output shaft 201 is a hollow structure, and the wire harness can pass through the shaft center, and the corresponding shaft end face has a small annular area; the outer circular surface of the output shaft 201 is provided with an external thread, and the fifth step surface 2013 on the shaft is in contact with the corresponding surface 5011 of the actuator 501.

[0078] The solution using nut 5051 with washer 5041 and locking spring 5032 instead of disc spring and plug screw provides continuous positive pressure to the friction transmission component along the normal direction of the friction working surface. This is suitable for applications with limited space on the bobbin, such as... Figure 3 As shown.

[0079] When assembling a self-locking transmission structure with a friction clutch, place the self-locking transmission structure on the assembly device, such as... Figure 4As shown, the assembly and transposition includes a jig and a force application mechanism. The jig includes a base 700 and at least one flange 701. The flange 701 includes two abutting surfaces forming a right angle for limiting the motor along the radial and axial directions of the worm gear. The force-applying mechanism is an eccentric wheel 605 driven by an auxiliary drive structure. The auxiliary motor is fixed on the base of the fixture, and the eccentric wheel 605 is mounted on the output shaft of the auxiliary motor. The outer surface of the eccentric wheel 605 abuts against the drive motor 101 carrying the worm. The worm 100 of the transmission mechanism does not directly serve as the motor shaft. A driving synchronous pulley 1041 is fixedly connected to the output shaft of the motor 101, and a driven synchronous pulley is fixedly connected coaxially with the worm 100. The driving synchronous pulley 1041 and the driven synchronous pulley are connected by a synchronous belt 1042. The shaft of the worm 100 is constrained by a shoulder and a bearing on a bearing seat 1044. The bearing seat 1044 is fixed relative to the motor 101. The transmission backlash elimination mechanism is a guide rail 407-slider 406 scheme. The guide rail 407 is fixedly connected to the lower housing 301, and the slider 406 is fixedly connected to the motor 101 and the bearing seat 1044.

[0080] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A self-locking transmission structure with a friction clutch, wherein the self-locking transmission mechanism is a reduction transmission mechanism with self-locking characteristics, its input end is connected to a motor, and its output end is fixedly connected to an output shaft, the output shaft being connected to an actuator, characterized in that, A friction clutch mechanism is also provided between the output end of the self-locking transmission mechanism and the actuator. The friction clutch mechanism includes a positive pressure providing device and at least one friction transmission component. The at least one friction transmission component is disposed between the output shaft end face and the actuator, and the output shaft end face, the at least one friction transmission component and the actuator are in sequential contact with each other along the axial direction. At least one surface of the at least one friction transmission component forms a friction working surface with the adjacent component. The positive pressure providing device provides continuous positive pressure to the friction transmission component along the normal direction of the friction working surface, so that the friction transmission component is pressed against the adjacent component at the friction working surface.

2. The self-locking transmission structure with friction clutch device according to claim 1, characterized in that, When only one friction drive component is provided, one side of the friction drive component is fixedly connected to either the output shaft end face or one of the actuators, and the other side of the friction drive component is in relative rotatable contact with either the output shaft end face or another actuator. The surface of the friction drive component that is in relative rotatable contact with the output shaft end face or the actuator forms a friction working surface.

3. The self-locking transmission structure with friction clutch device according to claim 1, characterized in that, When the number of friction transmission components is greater than 1, multiple friction transmission components are connected in series to form a transmission chain. The friction transmission components at both ends of the transmission chain are fixedly connected to the output shaft and the actuator, respectively. Two adjacent friction transmission components in the transmission chain can rotate relative to each other and form a friction working surface.

4. The self-locking transmission structure with friction clutch device according to claim 1, characterized in that, The positive pressure providing device provides a positive pressure F to the contact surface between the friction drive component and the output shaft end face or the actuator, satisfying the following conditions: T1<μ0F <T2……(1) T1 ≤ μF……(2) Where T1 is the minimum torque required to drive the actuator, T2 is the maximum torque that the output end can withstand when the transmission mechanism does not fail, μ0 is the maximum static friction coefficient between the friction transmission component and its non-fixed surface, and μ is the dynamic friction coefficient between the friction transmission component and its non-fixed surface.

5. The self-locking transmission structure with friction clutch device according to claim 1, characterized in that, The friction drive component is a friction plate, which is fixedly connected to the end face of the output shaft or any of the actuators by applying adhesive or screws.

6. The self-locking transmission structure with friction clutch device according to claim 1, characterized in that, The positive pressure providing device includes a fastener and a pressure component. One end of the fastener is fixedly connected to the output shaft. The pressure component generates elastic force under pressure. The elastic force is transmitted to the friction working surface through the contact surface between the positive pressure providing device and the actuator and / or friction transmission component.

7. The self-locking transmission structure with friction clutch device according to claim 6, characterized in that, The pressure component is an elastic element, which provides a floating stroke along the positive pressure direction. The component of the elastic force of the elastic element at different compression positions in the normal direction of the friction surface is the positive pressure F.

8. The self-locking transmission structure with friction clutch device according to claim 7, characterized in that, The elastic element consists of at least two disc springs, with adjacent disc springs installed facing each other along the positive pressure direction.

9. The self-locking transmission structure with friction clutch device according to claim 7, characterized in that, The fastener is a stopcock, the end face of the output shaft is provided with a threaded hole, the threaded section of the stopcock passes through the through hole of the actuator and is screwed into the threaded hole, and the elastic element is sleeved around the smooth section of the stopcock.

10. The self-locking transmission structure with friction clutch according to claim 6, characterized in that, A friction-reducing component is also provided between the contact surfaces of the positive pressure providing device and other components. The friction-reducing component is used to reduce the frictional torque when the positive pressure providing device and the actuator rotate relative to each other.

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