Variable-pitch worm gear mechanism

Abstract

The application discloses a variable locking worm and gear mechanism and belongs to the technical field of worm and gear transmission. In view of the inherent defects of the fixed reverse transmission state (either self-locking or non-self-locking) of the traditional worm and gear, the application first proposes the concept of "dynamic variable locking", breaking the contradiction between efficiency and safety. The mechanism realizes the intelligent switching between the "high-efficiency transmission (non-locking)" and "safety locking" states through one or more combinations of the high and low friction coefficient meshing area, the positioning spring, the rotary damper, the end face ratchet pair, the electric control board and the damping motor and other components integrated on the worm. The application integrates the transmission, clutch and brake functions in one, has compact structure, fast response and high reliability, and is particularly suitable for the occasions requiring dynamic safety locking, such as elevators, roller coasters and mine machinery.

Description

Technical Field

[0001] This invention relates to the field of worm gear transmission technology, specifically to a variable locking worm gear mechanism whose locking state can be dynamically changed. Background Technology

[0002] In traditional worm gear mechanisms, the self-locking characteristic during reverse transmission is determined by the lead angle and the coefficient of friction, which is fixed once the manufacturing is completed. If self-locking safety is pursued, transmission efficiency must be sacrificed (small lead angle), resulting in severe heat generation. If high efficiency is pursued (large lead angle), self-locking is lost. This "fixed state" severely limits its application in advanced mechanical systems that require intelligent switching between transmission and locking states. Summary of the Invention

[0003] 1. Terminology Definition Locked state: The worm gear rotation is completely suppressed, and the mechanism cannot reverse the transmission; In the unlocked state: the worm gear can rotate freely, and the reverse transmission of the mechanism is smooth; Semi-locked / semi-clutch / semi-limited slip state: The worm gear speed is significantly reduced but not completely stopped, and the mechanism transmits part of the torque; this state is usually achieved by controlling the rotational damper (13) to engage while the end face ratchet pair (11,12) is not engaged, or it can be achieved by controlling the resistance torque through the damping motor.

[0004] 2. Purpose of the Invention The purpose of this invention is to provide a variable locking worm gear mechanism that solves the technical problems of the invariable reverse transmission state of traditional worm gears and the difficulty in balancing efficiency and safety, and enables the mechanism to intelligently switch the locking state according to the working conditions during operation.

[0005] 3. Technical Solution The core of this invention lies in dynamically changing the "comprehensive resistance torque" when the worm gear is reverse-driven; when the worm gear is the driving wheel, by changing the resistance torque of the worm, it can switch between the "locked" (the worm does not rotate or hardly rotates) and "unlocked" (the worm rotates significantly) states. To achieve this objective, the present invention adds a locking switching component to the traditional worm gear, the component comprising one or more combinations of the following functional modules: Actuator: Includes a speed reducer (used to increase worm resistance) and a locking device (used to rigidly prevent worm rotation); Triggering structure: such as a positioning spring, used to sense the worm gear speed (by axial force) and mechanically trigger the actuator; Controller: such as an electric control board or a damping motor, used to actively control the actuator to change the resistance torque or axial position of the worm gear.

[0006] The controller is configured to execute a closed-loop control method: when the worm gear speed is detected to exceed a first threshold, the speed reducer is controlled to engage to increase the worm resistance; when the worm gear speed is detected to drop to a second threshold, the locking device is controlled to engage to achieve rigid locking; wherein the first threshold is greater than the second threshold, thereby allowing the mechanism to switch between a locked state and an unlocked state. 4. Detailed Implementation This invention provides various embodiments, covering multiple technical paths from purely mechanical to intelligent electronic control: Example 1 (basic type, mechanical one-way locking): The worm extends axially into a low-friction zone (non-self-locking) and a high-friction zone (self-locking), and the initial engagement position (low-friction zone) is maintained by a positioning spring; when the worm wheel speed exceeds the limit, the axial force overcomes the spring force, and the worm moves to the high-friction zone to achieve locking; Example 2 (Mechanical bidirectional locking): The worm gear has high friction zones at both ends and a low friction zone in the middle, with positioning springs at both ends; locking can be triggered by high-speed rotation of the worm wheel in both directions. Example 3 (Mechanical + Electrical Dual Control): An electric control board is added to the mechanical structure, with electrical control taking priority and mechanical triggering as a safety redundancy; Examples 4-6 (High-performance electronically controlled type): Introducing components such as a rotary damper, end face ratchet pair, and damping motor; the controller precisely controls the deceleration and locking sequence to achieve smooth locking, and can be extended to provide a "semi-locking" function (usually requiring a position sensor to provide feedback on the worm gear position). The high friction coefficient region (3) and low friction coefficient region (4) on the worm (5) can be achieved through a variety of mature material processing technologies, including but not limited to: Surface coating technologies: such as thermal spraying, electroplating, physical vapor deposition (PVD) or chemical vapor deposition (CVD) coating materials with different coefficients of friction; Inlay or composite manufacturing: such as inlaying or cladding low-friction coefficient material blocks such as copper alloys and engineering plastics onto an alloy steel worm gear substrate; Those skilled in the art can select any of the above processes or combinations thereof, or other similar processes, according to the required coefficient of friction, wear resistance and cost requirements; the key requirement is to ensure that the high and low friction zones are firmly bonded to the worm gear base, that the transition between the high and low friction zones is smooth, and that the friction performance is stable during long-term use.

[0008] 5. Beneficial effects Intelligent and controllable: Supports pure mechanical triggering, electric control and electromechanical dual control modes, with fast response and high precision. The electric control mode supports semi-locking function. High efficiency and safety: High efficiency when not locked, and safe and reliable when locked, resolving the contradictions of traditional technologies; Wide range of applications: Suitable for high-end applications such as clutches and safety speed limiting devices (e.g., roller coasters, elevators). Attached Figure Description

[0009] Figure 1 Basic type 1 (one-way self-locking, mechanical).

[0010] Figure 2 Basic type 2 (two-way self-locking, mechanical).

[0011] Figure 3 Schematic diagram of the thread on the worm (straightened form).

[0012] Figure 4 Improved version 1 (two-way locking, mechanical + electronic control).

[0013] Figure 5 Improved type 2 (two-way locking, mechanical + electric control).

[0014] Figure 6 Improved Type 3 (two-way locking, electronically controlled).

[0015] Figure 7 Improved Type 4 (Two-way locking, electrically controlled)

[0016] Unified caption: 1 – Left positioning spring; 2 – Right positioning spring; 3 – Left and right high friction coefficient threads; 4 – Middle low friction coefficient thread; 5 – Worm; 6 – Worm wheel; 7 – High friction coefficient surface (approximately 1 / 3 of the length); 8 – Low friction coefficient surface (approximately 2 / 3 of the length); 9 – Left electric control board; 10 – Right electric control board; 11 – Left end face ratchet pair; 12 – Right end face ratchet pair; 13 – Left and right rotary dampers (one-way); 14 – Area on the worm that engages with the rotary damper; 15 – Damping motor; 16 – Damping driven wheel; 17 – Damping driving wheel. Detailed Implementation

[0017] Example 1 This embodiment is the basic type one (one-way locking, mechanical): refer to... Figure 1 As shown, one end of the traditional worm (5) is lengthened to form two meshing areas (area 4 + area 3). When the driving wheel worm rotates counterclockwise, the left side of the worm meshing surface (and the back meshing surface) is a low friction coefficient area (4), which meshes with the worm wheel in the opposite direction and does not self-lock. The right side of the worm meshing surface is a high friction coefficient area (3), which is designed to mesh with the worm wheel in the opposite direction and fall within the self-locking range. A positioning spring (1) is provided at the left end of the worm. The worm wheel (6) can rotate in both directions. When the worm wheel rotates counterclockwise at low speed, the axial force it generates on the worm is insufficient to overcome the elastic force of the positioning spring (1), and the worm will not produce a large axial offset. Its meshing with the worm wheel is non-self-locking. When the worm wheel speed increases to a certain threshold (first threshold), the axial force generated by the worm wheel on the worm is large enough to overcome the set value of the positioning spring force, and the worm will produce a significant leftward offset. [Since the low friction zone is formed by replacing the surface metal material in the high friction zone and then smoothly transitioning to the high friction zone through precise post-processing, it can ensure that the worm...] When the rod (5) moves axially, the meshing transition is smooth and there is no impact. It meshes with the worm wheel in the high friction coefficient area (3) on the right. The speed of the worm wheel decreases to the second threshold, and then self-locking occurs. The worm wheel and worm gear transmission pair is locked. At this time (locked state), if the worm wheel rotates in the opposite direction (clockwise), the worm wheel meshes with the low friction coefficient area on the back of the worm thread. The meshing surface with the worm is a low friction pair. The self-locking is released, the worm can rotate, and under the action of the positioning spring force, the worm returns to the right end position. This process repeats... The worm wheel of this type of drive wheel rotates at low speed and locks in one direction at high speed. To ensure the performance of the high and low friction coefficient zones, this embodiment uses laser cladding of copper alloy on a steel worm base to form the base metal of the low friction zone, and precision grinding to ensure that the worm thread tooth profile is consistent and continuous. Through this (or similar process), the base steel of the worm (5) and the copper alloy covering can have sufficient bonding strength and transition performance between the high and low friction coefficient zones. The features of this embodiment are: the worm gear, which acts as the driving wheel, does not lock at low speeds and locks in one direction at high speeds; it is mechanical and highly reliable; the worm does not output power, resulting in low power consumption; the mechanism switches between idling (not locked) and locking, resulting in low frictional loss and low maintenance costs.

[0018] Example 2 This embodiment is the basic type two (two-way locking, mechanical): refer to... Figure 2 , Figure 3As shown, this type is based on the basic type 1 and is extended to a two-way locking structure. The specific method is to lengthen both ends of the traditional worm (5) to form three meshing areas (4 areas + 3 areas on the left and right); the middle is a low friction coefficient area (4), which meshes with the worm wheel and drives in the opposite direction without self-locking; the two sides are high friction coefficient areas (3), which are designed to mesh with the worm wheel and drive in the opposite direction within the self-locking range; each end of the worm is equipped with a positioning spring (1, 2), and the worm wheel is the driving wheel, which can rotate in both directions. When the worm wheel rotates at low speed, the axial force it forms on the worm is insufficient to overcome the positioning spring force, so the worm will not produce a large axial movement. The meshing with the worm wheel is non-self-locking; when the worm wheel speed increases to a certain threshold, the axial force generated by the worm wheel on the worm is large enough to overcome the set value of the positioning spring force, the worm will deviate significantly and mesh with the worm wheel in the high friction coefficient area (3) on one side, thereby generating self-locking and locking the transmission pair; at this time (locked state), if the worm wheel rotates in the opposite direction, the worm wheel meshes with the back of the worm thread (low friction coefficient area), and the meshing surface with the worm is a low friction pair, the self-locking is released, the worm can rotate, and under the action of the positioning spring force, it returns to the center position, and so on...; the worm wheel of this type of drive wheel rotates at low speed and locks in both directions at high speed; See Figure 2 The extended worm thread base is made of high-friction material (region 7) (such as steel), and low-friction material (such as copper alloy) is inlaid in 2 / 3 of the length of the meshing surface on both sides of the thread (region 8). Because the transition area between the high and low friction zones is smoothly formed after the secondary machining of the worm gear, and its external shape and surface machining accuracy are consistent, it can cope with applications that require high frequency and bidirectional reliable locking, so as to ensure the stability and life of long-term operation. The features of this embodiment are: the worm gear, which acts as the driving wheel, does not lock at low speeds and locks at high speeds; it is mechanical and highly reliable; the worm does not output power, resulting in low power consumption; the mechanism switches between idling (not locked) and locking, resulting in low frictional loss and low maintenance costs.

[0019] Example 3 This embodiment is an improved version one (two-way locking, mechanical + electronic control): refer to Figure 4 Based on the basic model 2, the two ends of the worm pass through the positioning spring and are equipped with a left electric control plate (9) and a right electric control plate (10) to control the worm to move to the left and right, and play a dual-control locking (electric locking and mechanical locking) role. The features of this embodiment are: on the basis of the advantages of the basic model, an electric control function is added, which can achieve more precise control. During normal operation, electric control is used to be precise and convenient, and mechanical control can be used to supplement and fall back in case of electric control failure. When the transition zone between the high and low friction coefficient zones (3, 4) is made to a certain bandwidth (i.e., a gradual transition), the semi-locking function of the worm gear mechanism can be realized by precisely controlling the position of the worm through the electric control board. If the high friction coefficient area (3) on the left and the right positioning spring (2) are removed from this embodiment, it becomes the basic type with one + electronic control function, that is, only one-way lock function.

[0020] Example 4 This embodiment is an improved version two (two-way locking, mechanical + electronic control): refer to... Figure 5 Based on the improved version 1, the original high friction coefficient area (3) on the worm gear was removed, a left and right rotation damper (13) (one-way damping) was added, a left and right end face ratchet locking pair (11, 12) was added, and the setting position of the left and right electric control plates (9, 10) was moved to make its structure more reasonable. The working idea of ​​this embodiment is: the lead angle of the worm can be designed to be larger, so that the resistance and energy consumption of the worm wheel are smaller at low speed. The worm wheel rotates with the worm in idle mode. When the speed of the worm wheel reaches the set value, the axial force of the worm increases and the worm begins to move significantly to the side of the axial force. At this time, the damper engagement area (14) on this side first engages with the rotary damper on the same side. The damper works and prevents the worm from rotating to lock. The locked state further increases the axial force and the movement of the worm also increases further until it engages with the end face ratchet pair on the same side. If the worm wheel in the locked state starts to rotate in the opposite direction, since the rotary damper is unidirectional, under the action of the positioning spring (1 or 2), the worm easily returns to the middle position, and the worm wheel and worm gear transmission pair returns to the idle state (non-self-locking). If the reverse rotation speed of the worm wheel increases to the set value, it enters the reverse locking state, and so on... The above describes the working principle of the purely mechanical structure. When an electric control board (9, 10) is added as a controller, the axial movement of the worm can be controlled more precisely, thus achieving the dual control function of mechanical + electric control in the worm gear transmission state. The end face ratchet pair is the final locking device, and the rotary damper is the speed reducer. During normal operation, electric control is used for precision and convenience. When electric control fails, mechanical control is used to supplement and fall back in time. By precisely controlling the position of the worm gear through the electric control board, the semi-locking function of the worm gear mechanism can be realized (rotation damper engaged, end face ratchet pair not engaged); the semi-locking state can receive the speed feedback signal of the worm (5) through the controller (such as ECU) and adjust the position of the electric control board (9, 10) to achieve closed-loop stable control. The controller can trigger the locking device after determining that the deceleration condition is met, based on preset logic, timing, or feedback signals from sensors (such as worm gear speed sensor signals). If the left rotary damper (13), the left engagement area (14), the left end ratchet pair (11) and the right positioning spring (2) are removed from this embodiment, only the one-way locking function (mechanical + electronic control) will be available.

[0021] Example 5 This embodiment is an improved type three (two-way locking, electrically controlled): Refer to... Figure 6 Based on the improved version 2, the left and right positioning springs (1, 2) are removed, and the electric control board is replaced with a curved plate that can move the damper and the end face ratchet at the same time. The working principle of this embodiment is as follows: the worm is axially fixed and cannot be displaced. The left and right electric control plates (9, 10) can move synchronously towards the center (or outwards). During the synchronous movement of the left and right electric control plates towards the center, the left and right dampers (13) are first pushed into the engagement area (14). At this time, the total torque (i.e., the combined resistance torque) after the damper torque on the worm is superimposed on its friction torque is greater than the driven torque transmitted to the worm by the worm wheel. The worm stops rotating, and the worm wheel and worm lock. Then, the electric control plate pushes the outer side (moving side) of the end face ratchet (11, 12) pair closer to the inner side for engagement, thereby achieving the locking (i.e., the locking does not loosen due to the change in damper resistance). Conversely, when locked, when the left and right electric control plates move outwards, the locking is released, and the worm can rotate freely. The end face ratchet pair is the final locking device, and the rotary damper is the speed reducer. By precisely controlling the position of the worm gear through the electric control board, the semi-locking function of the worm gear mechanism can be realized (rotation damper engaged, end face ratchet pair not engaged); the semi-locking state can receive the speed feedback signal of the worm (5) through the controller (such as ECU) and adjust the position of the electric control board (9, 10) to achieve closed-loop stable control. If the left rotary damper (13), left engagement area (14), left end ratchet pair (11) and left electric control board (9) are removed in this embodiment, only one-way locking function (electrically controlled) is available.

[0022] Example 6 This embodiment is an improved version four (two-way locking, mechanical + electronic control): refer to Figure 7 Based on the improved version 2, the original left and right rotation damper (13, unidirectional damping), damping engagement area (14) and left and right electric control plates (9, 10) on the worm gear were removed, and a damping motor (15), damping drive wheel (16) and damping driven wheel (17) were added to make its structure more reasonable. The working idea of ​​this embodiment is as follows: the two-way mechanical locking function of the improved type 2 is still retained. Although this function may not be very friendly to the end face ratchet (high wear), the original damper and electric control board are replaced by a newly added damping motor. The torque of the damping motor is transmitted to the worm through the damping driving wheel (16) and the damping driven wheel (17). When the worm wheel changes from low speed to high speed, the axial force on the worm increases. When it is greater than the positioning spring force, the worm moves to one side until the ratchet engages. At this time, it is a mechanical engagement. When the worm wheel speed has not increased or has just increased, the damping motor starts and increases the resistance torque to the worm until it is locked. The end face ratchet pair engages (when the engagement is completed, the damping motor is de-energized and there is no damping force). If the worm wheel reverses at this time, the worm returns to the middle free-spinning position under the action of the positioning spring force. The end face ratchet pair is the final locking device, and the damping motor is the speed reducer. Another advantage of the damping motor is that it can precisely control the magnitude of the resistance torque, so that the mechanism is in a "semi-locked" state. When the mechanism is applied to the clutch, it can play a semi-clutching function. By controlling the output torque of the damping motor (15), the resistance torque applied to the worm (5) can be dynamically balanced with the driven torque transmitted from the worm wheel (6), thereby realizing the slow rotation or creep of the worm, i.e., the "semi-locked" state. This function is usually completed by external computer control (such as ECU). The implementation of the "semi-lock" function usually requires an external controller (such as an ECU) to calculate the required resistance torque based on the target state (such as the clutch slip ratio) and send a corresponding control command to the damping motor (15). The damping motor (15) receives a control signal from the clutch controller or the vehicle ECU, which is calculated based on the target slip ratio or the target output torque, thereby driving the damping motor to output a precise resistance torque and achieve a stable semi-lock state.

[0023] In summary, different combinations of the above composite devices can lead to various composite worm gear transmission mechanisms, each with its own performance emphasis, which will not be listed here.

Claims

1. A variable locking worm gear mechanism, comprising a worm wheel (6), a worm (5), and a housing, characterized in that, It also includes a lock-to-change component; The locking switching component is configured to dynamically change the combined resistance torque of the worm (5) during reverse transmission, thereby switching the mechanism between a locked state and an unlocked state.

2. The variable locking worm gear mechanism according to claim 1, characterized in that, The lock-up switching component includes an actuator and a triggering structure; The actuator includes a speed reducer and a locking device; The triggering structure is configured to drive or allow the actuator to change the resistance torque of the worm (5) in response to changes in operating conditions.

3. The variable locking worm gear mechanism according to claim 2, characterized in that: The speed reducer is selected from one or more of the following: the high friction coefficient meshing area of ​​the worm gear (3) and the rotary damper (13); The locking device is selected from one or more of the high friction coefficient meshing area of ​​the worm gear (3) and the end face ratchet pair (11, 12); The triggering structure is a positioning spring (1, 2), which is used to maintain the worm position when there is no external command, and to allow the worm to move when the axial force generated by the worm wheel speed exceeds a set threshold.

4. The variable locking worm gear mechanism according to claim 1, characterized in that, The locking switching component includes an actuator and a controller; The actuator includes a speed reducer and a locking device; The controller is configured to actively control the actuator to change the resistance torque or position of the worm (5).

5. A variable locking worm gear mechanism according to claim 4, characterized in that: The speed reducer is selected from one or more of the following: worm gear high friction coefficient meshing area (3), rotary damper (13), and damping motor (15); The locking device is selected from one or more of the high friction coefficient meshing area of ​​the worm gear (3) and the end face ratchet pair (11, 12); The controller is selected from one or more of the electric control board (9, 10) and the damping motor (15).

6. A variable locking worm gear mechanism according to claim 4 or 5, characterized in that, The controller is configured to dynamically adjust the output torque of the damping motor or the position of the electric control board based on the worm speed or position feedback signal, so as to maintain the worm rotating at a specific slip ratio and enable the mechanism to achieve a semi-locked state.

7. A locking timing control method for a variable locking worm gear mechanism, characterized in that, Includes the following steps: Monitor the rotational speed of the worm wheel (6) or the axial force on the worm (5); When the rotational speed exceeds the first threshold or the axial force exceeds the set value, the speed reducer is activated to increase the resistance torque of the worm (5) and reduce the rotational speed of the worm (5). When the rotational speed of the worm (5) is detected to drop to the second threshold, the locking device is controlled to engage in order to achieve rigid locking of the worm (5); Wherein, the first threshold is greater than the second threshold.

8. A locking control method for a variable locking worm gear mechanism, characterized in that, Includes the following steps: Real-time monitoring of operating parameters, including one or more of the following: worm wheel (6) speed, worm (5) axial force, or worm (5) speed; When it is necessary to enter the locking state, control the locking switching component to increase the overall resistance torque of the worm (5) until the mechanism enters the locking state; When it is necessary to release the locked state, the locking switching component is reset to reduce the overall resistance torque of the worm (5) until the mechanism exits the locked state and returns to the non-locked state.

Images