Harmonic speed reduction-ratchet wheel plate spring composite dual-mode elastic driver

Abstract

The invention relates to a harmonic speed reduction-ratchet wheel plate spring composite dual-mode elastic driver. The harmonic speed reduction-ratchet wheel plate spring composite dual-mode elastic driver comprises a motor shell, a driving motor, a harmonic speed reducer and a plate spring energy storage-cam release mechanism. The motor shell comprises a middle shell, a front cover and a rear cover; an input shaft of the harmonic reducer is fixedly connected with the flange; a wave generator is formed through a flange; the plate spring energy storage-cam release mechanism is composed of a ratchet wheel, a bidirectional pawl, a plate spring and a mode switching mechanism. The driver has two working modes: 1, a conventional deceleration mode: a bidirectional pawl locks a ratchet wheel, and high-reduction-ratio torque is output through a harmonic reducer; and 2, an elastic energy storage mode: when the output end is impacted, the outer ring of the ratchet wheel rotates and stretches the plate spring to store energy, and the cam pawl can limit the reverse rotation and release the plate spring. The dual-mode switching mechanism has the dual-mode switching capacity, high precision and impact resistance, the instantaneous driving explosive force is remarkably improved, energy is efficiently stored, energy consumption is reduced, and the dual-mode switching mechanism is suitable for collaborative robot joints, high-dynamic load equipment and other scenes.

Description

Technical Field

[0001] The present invention relates to the field of elastic drivers, in particular to a dual-mode elastic driver of a harmonic speed reducer-ratchet leaf spring composite. Background Art

[0002] With the continuous advancement of biomimetics, articulated robots, represented by exoskeletons, quadrupeds, and humanoid robots, have become a research focus. These robots are required to achieve rapid obstacle avoidance and sudden movements in complex and dynamic environments. The instantaneous power output and environmental adaptability of their joint actuators have become key factors influencing their overall motion performance. The efficient energy utilization mechanisms of biological leg systems suggest that ideal biomimetic joints should possess both high-precision transmission and instantaneous energy release capabilities.

[0003] Currently, mainstream motor drives mostly use traditional rigid transmission structures, such as gearboxes. These structures struggle to achieve high instantaneous torque output within confined spaces, resulting in low power density. During high-speed dynamic motion, the motor's continuous operation leads to significantly increased energy consumption, and the inability to recover impact energy results in low energy efficiency. In the face of sudden external impacts, the motor lacks effective unloading capabilities, making it susceptible to damage from overload and even posing safety risks to operators. In humanoid devices such as exoskeletons and prosthetics, these issues make the system bulky and slow, making it difficult to meet the flexibility and energy efficiency requirements for safe collaboration with humans.

[0004] Elastic drives partially alleviate the above problems by introducing energy storage elements such as leaf springs: they have a certain impact resistance, and the elastic elements can absorb transient impacts to improve system safety; at the same time, the stored kinetic energy can be released when needed, thereby enhancing the instantaneous explosive force of the drive and improving peak power output.

[0005] However, existing elastic actuators still have obvious shortcomings: the driving mode cannot be switched flexibly or relies on complex control systems to achieve mode switching, which increases energy consumption and the probability of failure; the energy storage components and transmission mechanisms are usually designed separately, which is difficult to directly integrate into the joints like rigid motors, resulting in structural redundancy and energy loss; in addition, it is difficult to achieve high-precision transmission and large deformation energy storage at the same time, and there are contradictions in mechanical design.

[0006] Therefore, developing a new elastic actuator that integrates high-precision deceleration, dual-mode switching, and efficient energy storage and release to comprehensively improve the dynamic response capability and energy efficiency of articulated robots has become one of the key technologies that urgently need to be broken through in this field. Summary of the Invention

[0007] The present invention aims to provide a dual-mode elastic actuator combining a harmonic reduction mechanism and a ratchet leaf spring to overcome the shortcomings of the existing technology. This actuator integrates a high-reduction-ratio harmonic reduction mechanism with a highly compliant elastic energy storage element, achieving higher peak torque output while maintaining low energy consumption. Furthermore, this integrated design effectively reduces the actuator's overall size and weight, improving its impact resistance and power density, and providing excellent buffering capabilities under high load conditions.

[0008] To achieve the above objectives, the present invention adopts the following technical solutions:

[0009] A dual-mode elastic drive with a harmonic reduction and ratchet leaf spring composite structure mainly includes a drive housing, a frameless torque motor, a bidirectionally controllable harmonic reduction mechanism, a leaf spring energy storage and cam release assembly, and an output shaft. The drive housing is composed of an encoder fixing, a motor rear cover, a middle shell with two ratchet fixing holes (for fixing the leaf spring and motor stator), and a front cover for overall packaging. The frameless torque motor includes a motor rotor, a stator, and a motor shaft, which are responsible for the power output of the drive. The bidirectionally controllable harmonic reduction mechanism is composed of a wave generator, a flexible wheel, and an inner ring rigid wheel-ratchet component with an integrated rigid wheel and ratchet structure, which is used to perform efficient harmonic reduction on the motor shaft. The leaf spring energy storage-cam release mechanism includes an elastic energy storage unit, a bidirectional ratchet locking system, and a mode switching device. The cam release action is controlled by gear transmission, thereby realizing switching between different working modes and energy storage and release.

[0010] Preferably, the wave generator flange is elliptical, with a major axis of 48 mm and a minor axis of 44 mm; the flexible wheel is made of a highly elastic alloy material, has a straight tooth structure with a module of 0.5, 98 teeth, and a pressure angle of 20°, and an interference fit is achieved between its inner wall and the outer ring of the flange bearing using an H7 / p6 fit.

[0011] Preferably, the inner ring of the integrated rigid wheel-ratchet is designed as a straight tooth rigid wheel structure with a module of 0.5, a number of teeth of 100, and a pressure angle of 20°, while the outer ring is a ratchet structure with a module of 0.25, a number of teeth of 215, and a pressure angle of 20°.

[0012] Preferably, each of the two pawls is provided with a ratchet with a module of 0.25, a number of teeth of 2, and a pressure angle of 20°, and is connected to the middle housing through a variable diameter spring, which effectively prevents the pawl from shaking during operation.

[0013] The three leaf springs used as energy storage elements are preferably of 4mm outer diameter, 0.8mm wire diameter, and 24mm hook length, evenly spaced 120° around the circumference. One end of the leaf spring is fixed to an anchor point on the integrated rigid wheel-ratchet, and the other end is connected to the leaf spring mounting base on the middle housing. By replacing leaf springs with different stiffnesses, the energy storage performance can be adjusted, thereby optimizing the energy utilization efficiency of the drive.

[0014] Preferably, the mode switching mechanism controls the rotation direction of the bidirectionally controllable ratchet through a cam, thereby achieving dual-mode operation of the harmonic reduction mechanism. The mechanism drives the cam to rotate through a gear transmission, placing the pawls in different working areas. The engagement states of the two pawls are independent of each other: when both are engaged with the ratchet, the integrated rigid wheel-ratchet is locked, and the drive enters the normal reduction mode, outputting a high reduction ratio; in the elastic energy storage mode, the cam controls the pawls to be in three functional ranges: the left lift range (θ = 0°-20°) pushes the left pawl to disengage the ratchet teeth, while the right pawl remains engaged. At this time, the rigid wheel-ratchet can only rotate counterclockwise to store energy; the right lift range (θ = 20°-40°) pushes the right pawl to disengage and the left pawl to engage, limiting its rotation to clockwise to store energy; the central zero position range (θ = 40°-60°) causes both pawls to disengage simultaneously, releasing the potential energy stored in the leaf spring, driving the rigid wheel-ratchet to rotate freely in both directions, thereby outputting instantaneous high torque.

[0015] Preferably, the bidirectional controllable harmonic reduction mechanism is based on the principle of harmonic reduction and includes a wave generator, a flexspline, and an integrated rigid pulley-ratchet. The motor shaft is connected to the wave generator, which has an interference fit with the flexspline, which then meshes with the rigid pulley. The motor rotates the flexspline, and the difference in tooth count between the flexspline and the rigid pulley creates a 50:1 reduction ratio. The driving torque is transmitted from the motor shaft to the flexspline, then through the flexspline to the output shaft, ultimately acting on the load.

[0016] Working principle:

[0017] This drive combines a harmonic deceleration structure with an elastic energy storage mechanism, supporting both conventional deceleration and elastic energy storage operating modes. In conventional deceleration mode, the outer ratchet is secured by a pawl, and the system operates in a pure deceleration state. After the motor is started, it rotates the shaft, and power is transmitted to the flexspline via a wave generator. The elliptical profile of the flexspline causes it to deform and dynamically mesh with the rigid wheel. Because the flexspline has fewer teeth than the rigid wheel, each complete rotation produces a certain relative displacement, achieving a high reduction ratio and highly precise torque output. The output shaft is connected to the flexspline to ensure stable power output.

[0018] In elastic energy storage mode, the micromotor drives the cam through a gear transmission, causing the pawl on one side to engage with the ratchet wheel, allowing elastic energy storage in one direction. When the load is low, the system does not store energy. However, when the output shaft is subjected to a high load or impact force, the outer ratchet rotates under the action of torque, causing the leaf spring connected to it to undergo elastic deformation, converting the impact energy into elastic potential energy storage, which acts as a buffer and shock absorber. At this time, external impacts are not directly transmitted to the motor, effectively improving the stability and reliability of the drive system. When the load is reduced and operation returns to normal, the pawl releases the ratchet wheel, and the elastic element quickly resets and releases the stored energy, jointly providing output torque with the motor, increasing instantaneous power while improving overall energy utilization efficiency.

[0019] Through the coordinated control between the cam and the pawl, the system can realize elastic energy storage and power release in the clockwise and counterclockwise directions respectively, giving the drive bidirectional adaptive working capability.

[0020] The beneficial effects of the present invention are as follows:

[0021] 1. While retaining the traditional rigid joint motor drive form, the present invention introduces a harmonic reduction structure, which effectively improves the reduction ratio of the driver, enabling it to output a higher peak torque, thereby enhancing the instantaneous power performance of the articulated robot during dynamic motion.

[0022] 2. The present invention uses a micro-motor to drive the cam to switch to elastic energy storage mode. In this mode, when the actuator encounters an external impact, it absorbs the impact energy and converts it into stored elastic potential energy, releasing this energy at the appropriate time. This provides excellent buffering performance and energy utilization efficiency, enhancing the robot's safety in dealing with sudden loads while reducing overall energy consumption.

[0023] 3. The present invention adopts three leaf springs and fixes them by welding to ensure a stable connection. At the same time, it has a large deformation ability, thereby achieving a higher elastic energy storage capacity and improving the energy release capacity of the driver.

[0024] 4. The present invention highly integrates the motor, reduction mechanism and elastic energy storage module into one. The shell is made of aluminum alloy and the reduction mechanism adopts harmonic reduction. While ensuring a high reduction ratio and complete elastic drive function, it significantly reduces the volume and weight of the driver and improves its power density. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is an isometric assembly diagram of the present invention

[0026] Figure 2 This is an isometric diagram of the present invention

[0027] Figure 3Schematic diagram of the frameless motor structure and encoder of the present invention

[0028] Figure 4 Schematic diagram of the bidirectional controllable harmonic reducer of the present invention

[0029] Figure 5 Schematic diagram of the leaf spring energy storage-cam release structure of the present invention

[0030] Figure 6 Isometric diagram of the mode switching mechanism

[0031] Among them, 1 encoder, 2 encoder fixing part, 3 motor back shell, 4 bearing, 5 flange cover, 6 motor fixing part, 7 motor rotor, 8 motor stator, 801 stator winding, 802 stator body, 9 bearing, 10 cam release mechanism, 1001 left pawl, 1002 right pawl, 1003 variable diameter spring, 1004 driven gear, 1005 cam, 11 leaf spring, 12 bearing, 13 motor shaft, 14 middle cover, 15 bearing, 16 elliptical wave generator, 17 flexible wheel, 18 integrated rigid wheel-ratchet, 19 bearing, 20 front cover, 21 output shaft, 22 plug bolt, 23 micro motor, 24 driving gear. DETAILED DESCRIPTION

[0032] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings, but the protection scope of the present invention is not limited to the following.

[0033] Example 1:

[0034] Combine Figures 1 to 6 As shown, in this embodiment, the micro motor 23 drives the cam 1005 to rotate through gear transmission, so that the left pawl 1001 and the right pawl 1002 are engaged with the outer ring ratchet of the integrated rigid wheel-ratchet 18, thereby fixing the component and the drive enters the normal deceleration working mode.

[0035] When the windings 801 of the frameless motor stator 8 are energized, a magnetic field is generated that drives the motor rotor 7 to rotate, thereby driving the motor shaft 13. The motor torque is transmitted to the elliptical wave generator 16 in the bidirectionally controllable harmonic reduction mechanism, causing the flexspline 17 to elastically deform under the action of the wave generator, forming an elliptical shape. At this time, the inner ring of the integrated rigid wheel-ratchet 18 remains stationary, while the flexspline 17 engages with it after deformation. Along the major axis of the ellipse, the teeth of the flexspline 17 are fully engaged with the teeth of the rigid wheel; along the minor axis, the two are disengaged, with the intermediate region in a transitional state of gradual engagement and disengagement. This dynamic engagement causes the flexspline to displace relative to the rigid wheel during rotation. Because the flexspline 17 has 98 teeth, while the inner ring of the integrated rigid wheel-ratchet 18 has 100 teeth, the flexspline moves two tooth pitches in the opposite direction relative to the rigid wheel for each complete rotation of the wave generator, thus achieving a 50:1 reduction ratio. The output shaft 21 is fixedly connected to the flexible spline 17 to complete the power transmission process from the frameless motor to the output shaft.

[0036] Example 2:

[0037] refer to Figures 1 to 6 In this embodiment, in the initial state, the micro motor 23 drives the cam 1005 to rotate through gear transmission, so that the left pawl 1001 engages with the outer ratchet of the integrated rigid wheel-ratchet 18, and the right pawl 1002 is in a disengaged state. At this time, the cam is in the right lift area, and the driver only allows energy storage in the clockwise direction, entering the elastic energy storage working mode.

[0038] When the winding 801 of the drive motor stator 8 is energized, a magnetic field is generated to drive the motor rotor 7 to rotate, thereby driving the motor shaft 13 to move and transmitting the torque to the bidirectional controllable harmonic reduction mechanism. Under low-load operation, if the motor shaft 13 rotates counterclockwise when viewed from the side of the front cover 20, the output shaft 21 also rotates counterclockwise synchronously. At this time, the outer ratchet and pawl mechanism of the integrated rigid wheel-ratchet 18 remain stationary and do not affect the normal power transmission of the harmonic reducer. When the output shaft 21 encounters a high load or impact force, the outer ratchet of the integrated rigid wheel-ratchet 18 begins to rotate clockwise, driving the leaf spring 11 connected to it to elongate and deform, converting the external impact energy into elastic potential energy storage. The three leaf springs 11 jointly absorb the impact load during the force-bearing process, playing a good buffering and shock-resistant role, effectively improving the stability and safety of the system in complex environments. When the leaf spring 11 deforms to a set angle, the integrated rigid wheel-ratchet 18 stops rotating. Once the load returns to normal and the motor shaft 13 resumes counterclockwise rotation, the micromotor 23 drives the cam 1005 to rotate again, disengaging the left pawl 1001 from the outer ratchet ring and releasing the elastic potential energy stored in the leaf spring 11. At this point, the leaf spring quickly rebounds, driving the integrated rigid wheel-ratchet 18 counterclockwise, and together with the motor, it generates driving torque, significantly improving the driver's instantaneous power output while enhancing overall energy efficiency and reducing energy consumption.

[0039] Similarly, when the micromotor 23 drives the cam 1005 in the left lift range through a gear transmission, under low-load conditions, if the motor shaft 13 rotates clockwise when viewed from the front cover 20, the output shaft 21 also rotates clockwise. When the output shaft 21 encounters a high load or external impact, the outer ratchet of the integrated rigid-ratchet 18 rotates clockwise. At this point, the leaf spring 11, an elastic energy storage element, begins to stretch and deform in the clockwise direction, storing energy in the form of elastic potential energy. After the motor shaft 13 resumes normal clockwise rotation, the micromotor 23 drives the cam 1005 again, disengaging the pawl 10 from the outer ratchet of the integrated rigid-ratchet 18 and releasing the elastic potential energy stored in the leaf spring 11. This energy release causes the integrated rigid-ratchet 18 to rotate clockwise, and together with the driver, it outputs drive torque, further enhancing the system's dynamic response capability under transient conditions.

[0040] The present invention combines the advantages of high-precision deceleration of a harmonic reducer with the good impact resistance of an elastic energy storage structure. Through the synergistic effect of the ratchet-pawl control mechanism and the elastic element, the driver can effectively absorb energy when encountering external impacts and release it at the appropriate time to assist power output, realizing energy recovery and reuse and compound output functions. This design significantly enhances the impact resistance, operational stability, and transient response speed of the drive system in complex working conditions in applications such as robots, while effectively reducing energy consumption and improving energy efficiency. It is of great significance for the development of high-performance, long-life, and adaptive drive systems.

Claims

1. A dual-mode elastic driver with a harmonic speed reduction and ratchet leaf spring composite, comprising a motor housing, a drive motor, a bidirectionally controllable harmonic speed reduction mechanism, and a leaf spring energy storage-cam release mechanism. The motor housing consists of an encoder mount, a motor rear cover, a middle housing with two pawl mounting holes (for securing the spring and drive stator), and a front cover, providing overall support and encapsulation for the driver components. The drive motor, consisting of a rotor and stator, is connected to the input shaft via a flange. A magnet structure is embedded within the flange to transmit power to the motor. The bidirectional controllable harmonic speed reduction mechanism is composed of a wave generator, a flexible wheel and an integrated rigid wheel-ratchet (the inner ring is a rigid wheel structure). The wave generator consists of an elliptical fixing flange and eight deep groove ball bearings, which are fixed through threaded holes on the flange. The flexible spline is made of a highly elastic alloy material, and its inner wall is assembled with an interference fit on the outer ring of the bearing. The inner ring of the integrated rigid wheel-ratchet maintains an engaged state with the flexible spline to achieve efficient reduction transmission. The leaf spring energy storage-cam release mechanism includes an elastic energy storage unit, a pawl assembly, an integrated rigid wheel-ratchet (the outer ring is a ratchet structure) and a mode switching mechanism. The elastic energy storage part is composed of three leaf springs; the two pawls are fixed to the motor housing through annular grooves and a variable diameter spring; the ratchet is designed as a bidirectional ratchet structure, which is used to connect the energy storage leaf spring and control its response ability to the direction of external impact force; the outer ring ratchet of the bidirectional controllable ratchet is engaged with the two pawls to control its rotation direction. The mode switching mechanism consists of a micro motor, a driving gear, a driven gear and a cam. The micro motor is fixed on the front cover of the driver, and the driving gear is installed on its output shaft end and meshes with the driven gear for transmission; the cam is coaxially connected to the driven gear, and compresses the variable diameter spring through eccentric rotation, thereby driving the pawl to deflect at an angle to achieve the switching of the drive mode.

2. The dual-mode elastic actuator of harmonic speed reduction and ratchet leaf spring composite according to claim 1, characterized in that: The inner ring of the stator of the driver is fixed to the middle shell by bolts; the rotor of the driver is composed of magnetic steel, magnets and motor rotor end cover, and is connected to the rear cover through a flange cover and bearings; A bidirectional controllable harmonic reducer mechanism is installed in the inner cavity of the casing main body supporting the motor stator, which realizes bidirectional control of the bidirectional controllable harmonic reduction and two controllable energy storage directions.

3. The dual-mode elastic actuator of harmonic speed reduction and ratchet leaf spring composite according to claim 1, characterized in that: The inner ring of the integrated rigid wheel-ratchet is a straight tooth rigid wheel with a module of 0.5, a number of teeth of 100, and a pressure angle of 20°, and the outer ring is a ratchet with a module of 0.25, a number of teeth of 215, and a pressure angle of 20°.

4. The dual-mode elastic actuator of harmonic speed reduction and ratchet leaf spring composite according to claim 1, characterized in that: The leaf spring energy storage-cam release mechanism consists of an elastic energy storage element, a pawl, an integrated steel wheel-ratchet (outer ratchet), and a mode switching mechanism. The three leaf springs of the elastic energy storage element are made of spring steel, with a rest length of 20mm, an extended length of 80mm, and a thickness of 4mm. Each of the two pawls has ratchet teeth with a module of 0.25, two teeth, and a pressure angle of 20°.

5. The dual-mode elastic actuator of harmonic speed reduction and ratchet leaf spring composite according to claim 1, characterized in that: The mode switching mechanism is composed of a micro motor, a driving gear, and a driven gear. The driving gear has a module of 1, 16 teeth, and a pressure angle of 20 degrees. The driven gear has a module of 1, 32 teeth, and a pressure angle of 20 degrees.

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