A speed reducer with special worm and gear structure

Abstract

This application relates to the field of speed reducer technology, and in particular to a speed reducer with a special worm gear structure, comprising a housing, a power input shaft system, and a power output shaft system. The power input shaft system is equipped with a phase-compensated split worm gear assembly. The angular phase difference between the first and second worms is adjusted by a phase precision adjusting sleeve to eliminate backlash, and the tooth profile adopts a variable lead trajectory based on a modified cosine function to reduce meshing impact. The power output shaft system is equipped with a radially elastic load self-balancing worm gear. The gear ring is flexibly connected to the central hub through an elastic support ring composed of corrugated elastic elements, and damping grease is filled in the dovetail groove clearance. This application can improve return accuracy and transmission smoothness through phase compensation and variable lead design, and achieve load self-balancing by utilizing the radial deformation and damping energy dissipation of the elastic support ring, effectively reducing tooth surface fatigue wear and enhancing the system's impact resistance.

Description

Technical Field

[0001] This invention belongs to the field of speed reducer technology, specifically a speed reducer with a special worm gear structure. Background Technology

[0002] Worm gear reducers, as core components in precision transmission, primarily achieve speed reduction and torque increase through the meshing of a worm and a worm wheel, and are widely used in automated equipment. Conventional reducers typically employ a single worm and rigid worm wheel structure, relying on the lubricating medium inside the housing to reduce friction and aid heat dissipation. However, under high-precision or alternating load conditions, the limitations of traditional structures become increasingly apparent. Because the worm lead is fixed, the impact force upon entering the meshing zone affects transmission smoothness, and long-term wear leading to tooth backlash reduces positioning accuracy. Existing backlash compensation methods have room for improvement in adjustment accuracy and coaxiality maintenance. Furthermore, when dealing with asymmetrical loads, the rigid worm wheel exhibits uneven pressure distribution on the meshing surface, easily causing localized fatigue wear, and lacks an effective radial buffer and load self-balancing mechanism. Therefore, how to improve the meshing accuracy, reduce impact, and balance radial loads of reducers through structural innovation has become a key research direction for improving transmission system performance. Summary of the Invention

[0003] To achieve the above-mentioned objectives, this invention provides a speed reducer with a special worm gear structure. The speed reducer includes an upper housing, a lower housing, a power input shaft system, and a power output shaft system installed inside the speed reducer. The power input shaft system is equipped with a phase-compensated split worm gear assembly, which consists of a first worm, a second worm, and a phase precision adjustment sleeve disposed between the first and second worms. In a static assembly state, the phase precision adjustment sleeve adjusts the two worm segments to create a preset angular phase difference Δϕ, thereby eliminating backlash during meshing with the worm gear. The power output shaft system is equipped with a radial elastic load self-balancing worm gear, which is a split structure consisting of a central hub, an elastic support ring disposed around the central hub, and a gear ring covering the outer surface of the elastic support ring. The gear ring is flexibly connected to the central hub through the elastic support ring to balance the radial load during meshing through a flexible compensation mechanism.

[0004] Furthermore, the inner wall of the phase precision adjusting sleeve is provided with a high-precision internal spline, and the opposite ends of the first worm and the second worm are respectively provided with external splines that match the internal splines; the phase precision adjusting sleeve adjusts the relative angular displacement between the first worm and the second worm by changing the meshing tooth position of the internal splines and the external splines; a centering pin is also provided at the connecting end of the first worm and the second worm, and the positioning accuracy of the centering pin is controlled within 0.5mm to ensure the coaxiality of the two worm sections when rotating at high speed.

[0005] Furthermore, the tooth profiles of both the first and second worms employ a variable lead trajectory based on a modified cosine function, with a lead L... (x) The relationship between the x-axis and the x-axis follows the formula: Where L0 is the reference lead, A is the amplitude compensation coefficient, with a value ranging from 0.5 mm to 0.15 mm, and P is the period parameter determined based on the effective working section length of the worm. Through the variable lead trajectory, the worm has a smaller instantaneous lead when entering the meshing zone to reduce meshing impact, while returning to the standard lead in the central meshing zone.

[0006] Furthermore, the gear ring is made of tin bronze alloy, and its chemical composition by mass percentage is: tin Sn 11.0% to 13.0%, nickel Ni 1.5% to 2.5%, phosphorus P 0.1% to 0.2%, with the balance being copper Cu; the inner diameter surface of the gear ring is machined with a set of dovetail grooves evenly distributed along the circumference, and the cross-section of the dovetail grooves is V-shaped; the elastic support ring is composed of multiple independent corrugated elastic elements, and the elastic elements are made of 60Si2Mn silicon manganese spring steel with a hardness range of 45 to 50 HRC; one end of the elastic element is interference-fitted into the limiting hole of the central hub, and the other end slides into the dovetail groove of the gear ring, and the gap of the dovetail groove is filled with high-viscosity damping grease, and the damping grease provides a structural damping ratio ζ of 0.05 to 0.12.

[0007] Furthermore, when the elastic element is subjected to an asymmetric load impact, it undergoes radial and circumferential deformations. The deformation δ and the applied force F satisfy the nonlinearly modified Hooke's Law formula: F = k1δ + k2δ 3 Where k1 is the linear stiffness coefficient, used to maintain positioning accuracy under light load conditions; k2 is the nonlinear hardening coefficient, used to limit excessive radial offset of the gear ring under heavy load conditions, thereby ensuring that the normal force deviation of each meshing point under multi-point meshing conditions is controlled within ±3% of the design value.

[0008] The beneficial effects of this invention are as follows: By setting up a phase-compensated split worm gear assembly, and utilizing the cooperation of the phase precision adjusting sleeve and the internal and external splines, this invention achieves precise control over the phase difference between the first and second worm gears. This phase misalignment in the physical structure allows the helical surface of the worm gear to simultaneously engage with both sides of the worm wheel tooth groove, eliminating backlash caused by machining errors and wear without changing the center distance, thus significantly improving the return and positioning accuracy of the reducer.

[0009] This invention employs a variable lead trajectory design based on a modified cosine function to alter the relative velocity vector between the worm gear tooth surface and the worm wheel tooth surface at the moment of engagement. The variable lead structure smooths out the acceleration changes during meshing, effectively reducing the vibration amplitude and noise level of the transmission system during operation, and achieving a smooth transition in power transmission. Particularly under high-speed conditions, this structure reduces the impact stress between the tooth surfaces.

[0010] This invention constructs a radially elastic load-balancing worm gear, utilizing the radial flexibility of the corrugated elastic element and the shear energy dissipation effect of the damping grease in the V-shaped dovetail groove to form a load-balancing system with nonlinear stiffness. When the reducer is subjected to asymmetrical loads or instantaneous impact loads, the gear ring can generate a small radial adjustment displacement, allowing the load to be automatically distributed among multiple meshing tooth pairs. This avoids stress concentration caused by single-tooth overload, improving the system's impact resistance and structural reliability.

[0011] This invention utilizes the synergistic effect of corrugated elastic elements and damping grease to achieve dynamic stiffness compensation. Under low load conditions, the system maintains high stiffness to ensure transmission rigidity; under high load or impact conditions, the system absorbs energy through flexible deformation. This adaptive mechanical characteristic reduces the fatigue wear rate of the tooth surface. Simultaneously, the structural combination of the split worm gear and flexible worm wheel, through precision centering and damping vibration reduction, extends the service life of bearings and seals, reducing the frequency of equipment maintenance.

[0012] In summary, this invention, through structural innovation of the worm gear meshing pair, works synergistically from four dimensions: phase compensation, kinematic optimization, elastic support, and damping vibration reduction. It solves the contradiction between precision, stability, and load-bearing capacity that traditional reducers struggle to balance in high-precision transmission, and thus has extremely high engineering application value. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0014] The attached figures are labeled as follows: 1. Upper housing of the reducer; 2. Lower housing of the reducer; 3. Power output shaft system; 4. Center hub; 5. Elastic support ring; 6. Gear ring; 7. Dovetail groove; 8. First worm gear; 9. Second worm gear; 10. Phase precision adjustment sleeve; 11. Centering pin. Detailed Implementation

[0015] To enable those skilled in the art to understand the technical solution of the present invention more fully, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0016] This invention discloses a speed reducer with a special worm gear structure. The overall structure of this speed reducer with a special worm gear structure is as follows: Figure 1 As shown, it mainly consists of an upper reducer housing 1, a lower reducer housing 2, a power input shaft system, and a power output shaft system 3. The upper reducer housing 1 and the lower reducer housing 2 are mated together by precision-machined mating surfaces and secured by high-strength bolts after being positioned by cylindrical pins, forming a completely sealed power transmission chamber. The chamber is filled with gear oil to form a continuous lubricating oil film at each meshing part.

[0017] The power input shaft system is the core input end of this invention, and it integrates a phase-compensated split worm gear assembly. This assembly breaks through the structural limitations of traditional single worm gears, innovatively consisting of a first worm 8, a second worm 9, and a phase precision adjusting sleeve 10 positioned between them. The first worm 8 and the second worm 9 are arranged sequentially in the axial direction. To ensure the coaxiality of the two worm gears during high-speed rotation, a centering pin 11 is provided at the center of the connection end of the first worm 8 and the second worm 9. The centering pin 11 is inserted into the first worm 8 with an interference fit and into the corresponding hole of the second worm 9 with a clearance fit. Its positioning accuracy is strictly controlled within 0.5mm. This physical limitation eliminates the radial runout that may occur when the two worm gears rotate at high speed, maintaining the dynamic balance characteristics of the power input shaft system.

[0018] The inner wall of the phase precision adjusting sleeve 10 is machined with high-precision internal splines, while the outer circumferential surfaces of the opposite ends of the first worm 8 and the second worm 9 are respectively machined with matching external splines. In the assembled state, the phase precision adjusting sleeve 10 simultaneously covers and engages the external splines of the first worm 8 and the second worm 9 through the internal splines. By changing the relative meshing tooth positions of the internal and external splines, fine adjustment of the relative angular displacement between the first worm 8 and the second worm 9 is achieved. This adjustment mechanism generates a preset angular phase difference Δϕ, causing the helical tooth surface of the first worm 8 to conform to the left side of the worm wheel tooth groove, while the helical tooth surface of the second worm 9 conforms to the right side of the same worm wheel tooth groove. This bidirectional conformation eliminates backlash during the meshing process of the worm wheel and worm, and the reducer exhibits extremely high return accuracy even under frequent reversing or high-precision positioning conditions.

[0019] The tooth profiles of the first worm 8 and the second worm 9 are not traditional constant lead structures, but rather variable lead trajectories based on modified cosine functions. Their lead... Where L0 is the reference lead, A is the amplitude compensation coefficient ranging from 0.5mm to 0.15mm, and P is the periodic parameter determined based on the effective working length of the worm. Through this variable lead design, the worm has a small instantaneous lead at the initial stage of entering the meshing zone. At this time, the helix angle changes slightly, making the tangential relative velocity change when the worm tooth surface contacts the worm wheel tooth surface more gradual, eliminating the meshing impact caused by abrupt lead changes in traditional structures. When entering the central meshing zone, the lead returns to the standard value L0, ensuring a constant transmission ratio. This structure significantly reduces transmission noise and tooth surface contact stress in actual operation.

[0020] The radial elastic load self-balancing worm gear mounted on the power output shaft 3 adopts a split flexible design, which is fundamentally different from the traditional rigid worm gear. This worm gear consists of a central hub 4, an elastic support ring 5, and a gear ring 6 covering the outermost layer. The gear ring 6 is made of high-performance tin bronze alloy, with an optimized chemical composition, including, by mass percentage: 11.0% to 13.0% tin (Sn), 1.5% to 2.5% nickel (Ni), 0.1% to 0.2% phosphorus (P), and the balance being copper (Cu). The addition of nickel improves the alloy's hardness and corrosion resistance, while phosphorus improves its casting performance and wear resistance, making the gear ring 6 less prone to pitting or spalling under long-term high-load meshing.

[0021] The inner diameter surface of the gear ring 6 is machined with a set of dovetail grooves 7 evenly spaced circumferentially, and the cross-section of these dovetail grooves 7 presents a V-shaped structure. The elastic support ring 5 is composed of multiple independent corrugated elastic elements. These elements are made of 60Si2Mn silicon manganese spring steel, and after quenching and medium-temperature oil return treatment, their hardness range is maintained between 45 and 50 HRC. One end of each corrugated elastic element is inserted into the circumferentially distributed limiting holes of the central hub 4 through an interference fit, and the other end slides into the corresponding dovetail groove 7 of the gear ring 6 through a sliding fit. The fit gap between the dovetail groove 7 and the elastic element is filled with high-viscosity damping grease. This damping grease forms a damping film of limited thickness in the V-shaped space of the dovetail groove 7, providing a structural damping ratio ζ between 0.05 and 0.12.

[0022] When the reducer is under heavy load or subjected to asymmetric load impact, the gear ring 6 undergoes minute radial and circumferential deformations through the elastic support ring 5. The deformation δ and the applied force F satisfy the nonlinearly modified Hooke's law formula: F = k1δ + k2δ 3 Where k1 is the linear stiffness coefficient, used to maintain positioning accuracy under light load conditions; k2 is the nonlinear hardening coefficient, used to limit excessive radial offset of the gear ring 6 under heavy load conditions. This flexible compensation mechanism allows the gear ring 6 to generate adaptive micro-displacement when the worm gear is subjected to impact, thereby distributing the load across more meshing tooth pairs, ensuring that the normal force deviation at each meshing point is controlled within ±3% of the design value under multi-point meshing conditions, achieving a self-balancing load distribution.

[0023] The specific assembly and operation procedures for this speed reducer are as follows: S1: First, pre-assemble the power input shaft system. Connect the first worm 8 and the second worm 9 coaxially through the centering pin 11 and the phase precision adjusting sleeve 10 to ensure that the rotation axes of the two worms coincide. Find the optimal phase compensation point by rotating the sleeve.

[0024] S2: Assemble the power output shaft system, install the corrugated elastic element onto the center hub 4, and fill the dovetail groove 7 of the gear ring 6 with damping grease.

[0025] S3: Use specialized press-fitting equipment to press the gear ring 6 onto the outer periphery of the elastic support ring 5 to complete the overall construction of the flexible worm gear.

[0026] S4: Install the assembled input shaft system and output shaft system 3 into the bearing seats of the lower housing 2 of the reducer respectively, and fasten the upper housing 1 of the reducer and tighten the bolts.

[0027] S5: Inject lubricating oil through the oil injection hole and conduct no-load and full-load running-in tests.

[0028] In summary, this invention, through the deep integration of a split-type phase adjustment structure, a variable lead tooth profile design, and a flexible load balancing mechanism, resolves the contradiction between precision and lifespan in precision transmission at the physical structural level. The close cooperation between the various components and the clear operational logic, along with specific material selection and mathematical model constraints, ensure the feasibility and reliability of the technical solution in actual production. This structural innovation not only improves the static performance of the reducer but also achieves a significant leap in transmission system performance during dynamic operation through flexible compensation and damping vibration reduction.

[0029] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention. Parts not described in detail in this invention belong to the prior art known to those skilled in the art. All improvements, evolutions, and modifications based on the concept of this invention fall within the protection scope of this invention.

Claims

1. A speed reducer with a special worm gear structure, characterized in that, The speed reducer includes an upper housing (1), a lower housing (2), a power input shaft system, and a power output shaft system (3) installed inside the speed reducer. The power input shaft system is equipped with a phase-compensated split worm gear assembly, which consists of a first worm (8), a second worm (9), and a phase precision adjustment sleeve (10) disposed between the first worm (8) and the second worm (9). In the static assembly state, the phase precision adjustment sleeve (10) is used to adjust the two worm gears to maintain a certain distance between them. A preset angular phase difference Δϕ is used to eliminate backlash when meshing with the worm gear; a set of radial elastic load self-balancing worm gear is mounted on the power output shaft system (3). The worm gear is a split structure, consisting of a central hub (4), an elastic support ring (5) set around the central hub (4), and a gear ring (6) covering the outside of the elastic support ring (5); the gear ring (6) is flexibly connected to the central hub (4) through the elastic support ring (5) to balance the radial load during meshing through a flexible compensation mechanism.

2. The reducer with a special worm gear structure according to claim 1, characterized in that: The inner wall of the phase precision adjusting sleeve (10) is provided with a high-precision internal spline, and the opposite ends of the first worm (8) and the second worm (9) are respectively provided with external splines that match the internal splines; the phase precision adjusting sleeve (10) adjusts the relative angular displacement between the first worm (8) and the second worm (9) by changing the meshing tooth position of the internal spline and the external spline; the connecting end of the first worm (8) and the second worm (9) is also provided with a centering pin (11), and the positioning accuracy of the centering pin (11) is controlled within 0.5mm to ensure the coaxiality of the two worm sections when rotating at high speed.

3. A reducer with a special worm gear structure according to claim 1, characterized in that: The tooth profile curves of both the first worm (8) and the second worm (9) adopt a variable lead trajectory based on a modified cosine function, with a lead L. (x) The relationship between the x-axis and the x-axis follows the formula: Where L0 is the reference lead, A is the amplitude compensation coefficient, with a value ranging from 0.5 mm to 0.15 mm, and P is the period parameter determined based on the effective working section length of the worm. Through the variable lead trajectory, the worm has a smaller instantaneous lead when entering the meshing zone to reduce meshing impact, while returning to the standard lead in the central meshing zone.

4. A reducer with a special worm gear structure according to claim 1, characterized in that: The gear ring (6) is made of tin bronze alloy, and its chemical composition by mass percentage is: tin Sn 11.0% to 13.0%, nickel Ni 1.5% to 2.5%, phosphorus P 0.1% to 0.2%, with the balance being copper Cu; the inner diameter surface of the gear ring (6) is machined with a set of dovetail grooves (7) distributed at equal intervals along the circumference, and the cross-section of the dovetail grooves (7) is V-shaped; the elastic support ring (5) is composed of multiple independent corrugated elastic elements, and the elastic elements are made of 60Si2Mn silicon manganese spring steel with a hardness range of 45 to 50 HRC; one end of the elastic element is interference-fitted into the limiting hole of the central hub (4), and the other end slides into the dovetail groove (7) of the gear ring (6), and the gap of the dovetail groove (7) is filled with high viscosity damping grease, and the damping grease provides a structural damping ratio ζ of 0.05 to 0.

12.

5. A reducer with a special worm gear structure according to claim 4, characterized in that: The elastic element (10) generates radial and circumferential deformation when subjected to asymmetric load impact, and the deformation δ and the force F satisfy the nonlinear corrected Hooke's law formula: F=k1δ+k2δ 3 ; wherein k1 is a linear stiffness coefficient to maintain positioning accuracy under light load; k2 is a nonlinear hardening coefficient to limit excessive radial deviation of the gear ring (6) under heavy load conditions, thereby ensuring that the normal force deviation of each meshing point under multi-point meshing is controlled within ±3% of the design value.

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