Oscillating tooth speed reducer for eliminating transmission clearance by adopting wave exciter given deformation

Abstract

The invention discloses a movable tooth speed reducer for eliminating a transmission gap by adopting a wave exciter to give deformation, and belongs to the technical field of precision transmission. Wherein the main bearing assembly is composed of two rows of end face bearings and a row of radial bearings, and the radial bearings are arranged in the middle of the middle oscillating tooth frame, so that the total number of parts forming the main bearing assembly is four; a shock wave device is arranged between the eccentric shaft assembly and the oscillating tooth frame and comprises a shock wave device outer ring, a shock wave device inner ring and an annular elastic element located between the shock wave device outer ring and the shock wave device inner ring, and the elastic element is provided with preset radial deformation H and used for eliminating all transmission gaps in the speed reducer through radial elastic deformation in the initial driving stage. And the rigidity of the elastic element is set to enable the torque required for clearance elimination not to exceed 10% of the rated torque of the speed reducer. The manufacturing precision of the speed reducer is remarkably improved, the axial thickness and the weight of the speed reducer can be reduced by 10%-20%, and the bearing capacity consumed by clearance elimination is controlled within a certain range.

Description

Technical Field

[0001] The present invention relates to the technical field of precision transmission, and in particular to a movable tooth reducer which adopts a shock wave device to provide a given deformation to eliminate transmission clearance. Background Art

[0002] In the current field of high-performance CNC machine tools, composite transmission structures combining low-torque torque motors with high-precision reducers, gratings, brakes, and other components are becoming a key development direction for five-axis CNC rotary tables. These structures are often referred to as "quasi-direct-drive CNC rotary tables." Compared to torque motors with equivalent output torque, these rotary tables offer higher load capacity, smaller size, and lighter weight. This helps improve the acceleration response and rigidity control capabilities of the entire machine, while reducing overall system costs. Consequently, they are widely considered a key component of the next generation of five-axis machining centers.

[0003] Currently, there are many types of reducers used in quasi-direct-drive CNC turntables, including planetary reducers, RV reducers, harmonic reducers, and movable tooth reducers. These reducers have varying degrees of advantages and disadvantages in terms of structural principles, transmission rigidity, accuracy retention, and backlash control. Among them, traditional planetary reducers mostly use a double involute structure, with a limited first-stage reduction ratio, large transmission clearance and low rigidity, requiring an elastic anti-backlash device to meet the needs of precision control. A typical solution is the German PSC planetary reducer, which uses a tapered tooth axial compression method to achieve low backlash transmission. Although the backlash can be controlled within 6", its reduction stage mostly uses a combination of external meshing cylindrical gears and multi-stage planetary gears. The structure is complex, the axial taper modification technology is difficult, the processing accuracy and manufacturing cost are high, and the reduction ratio is also limited to less than 20. The RV reducer has a high reduction ratio and load capacity, but the presence of a needle tooth sliding contact link in the transmission results in high friction loss, making it difficult to maintain long-term precision, which is not conducive to the reliable operation of high-end five-axis rotary tables. Although the harmonic reducer has a high reduction ratio and a small size, its transmission efficiency is low and it tends to heat up during continuous operation, affecting the stability and service life of the system.

[0004] Therefore, in recent years, movable-tooth reducers, particularly those with double- or triple-roller structures, have been increasingly adopted for high-precision applications. By eliminating sliding friction, they improve reducer rigidity and precision retention, overcoming the shortcomings of RV and harmonic structures. A double-roller movable-tooth reducer with four-row cylindrical roller bearings outperforms RV structures in terms of transmission rigidity and backlash control, but suffers from the large number of main bearings and thicker structure.

[0005] In view of this, this application is hereby filed. Summary of the Invention

[0006] The purpose of the present invention is to provide a movable tooth reducer which adopts a given deformation amount of a shock wave generator to eliminate the transmission gap, so as to solve the problems raised in the above background technology.

[0007] Technical solution: A movable tooth reducer that uses a shock wave generator to provide a given deformation to eliminate transmission clearance, including an eccentric shaft assembly, a movable tooth carrier assembly, an inner gear ring assembly, a movable tooth assembly, and a main bearing assembly. The eccentric shaft assembly is used to provide input rotation and drive the movable teeth to move; The movable gear rack assembly includes a middle movable gear rack, a left movable gear rack and a right movable gear rack, which are used to carry movable teeth and transmit torque; The inner gear ring assembly is provided with fixed inner teeth for engaging with the movable tooth assembly; The movable tooth assembly includes an upper core shaft, a lower core shaft, a movable tooth ring and a K-type assembly, which is used to engage with the inner gear ring to realize motion conversion; The main bearing assembly is composed of two rows of axial cylindrical roller thrust bearings and one row of radial cylindrical roller bearings or needle roller bearings, and the radial cylindrical roller bearings are arranged in the middle of the center movable gear carrier, so that the total number of parts constituting the main bearing assembly is four, thereby integrating all main bearing raceways into a single center movable gear carrier; A shock wave generator is provided between the eccentric shaft assembly and the movable gear rack. The shock wave generator includes a shock wave generator outer ring, a shock wave inner ring and an annular elastic element located therebetween. The elastic element is designed with a preset radial deformation amount H, which is used to eliminate all transmission clearances inside the reducer through radial elastic deformation in the initial stage of driving, and the stiffness of the elastic element is set so that the torque required for eliminating the clearance generally does not exceed 10% of the rated torque of the reducer or is determined to be other proportions according to specific working conditions.

[0008] Preferably, the main bearing assembly includes a radial bearing, a bearing isolation ring and an end bearing, wherein: the radial bearing is a radial cylindrical roller bearing or a needle roller bearing, which is installed in the middle of the middle movable gear rack; the end bearing is two rows of axial cylindrical roller thrust bearings, which are symmetrically distributed on the two side end faces of the middle movable gear rack; the bearing isolation ring is arranged between the two rows of end bearings for axial positioning. This design allows the force flow to be evenly distributed, improves the output shaft rotation accuracy, avoids axial movement, and enhances high-speed stability.

[0009] Preferably, the right movable gear rack and the left movable gear rack are radially positioned by means of movable gear rack pins penetrating the middle movable gear rack; the right movable gear rack, the middle movable gear rack and the left movable gear rack are axially fixedly connected by movable gear rack locking screws. This design realizes radial positioning of the three-piece movable gear rack, ensures the coaxiality of the movable gear holes, simplifies the assembly process, and eliminates the risk of micro-wear between components.

[0010] Preferably, the inner gear ring assembly includes a left inner gear ring, a right inner gear ring and an inner gear ring spacer; the left inner gear ring and the right inner gear ring are circumferentially positioned by inner gear ring connecting pins, and are axially compressed by inner gear ring connecting screws; the inner gear ring spacer is arranged between the left inner gear ring and the right inner gear ring, and is used to control the width of the inner gear ring tooth groove, ensure the phase consistency of the inner gear ring tooth profile, and improve the meshing accuracy.

[0011] Preferably, the movable tooth ring is nested in the tooth groove of the movable tooth rack assembly, and the upper core shaft, K-type assembly and lower core shaft are installed in its inner cavity in sequence; the ends of the upper core shaft and the lower core shaft respectively abut the tooth profile curved surface of the inner gear ring, and the K-type assembly is used to provide radial elastic support, compensate for manufacturing tolerances, and reduce the impact noise between the movable teeth and the inner gear ring; at the same time, the upper and lower core shafts spherically contact the tooth profile, adapt to the inner tooth curved surface, and reduce eccentric load wear.

[0012] Preferably, the elastic element is embedded between the outer ring of the shock wave and the inner ring of the shock wave; deformation space is reserved on both radial sides of the elastic element, and its preset deformation amount H is controlled by the thickness of the elastic element and the installation pre-compression amount; the outer ring of the shock wave is axially limited by the shock wave baffle and the shock wave assembly spring clamp ring. This structure accurately covers all transmission chain gaps and prevents the shock wave from axially loosening, thereby ensuring the long-term effectiveness of the anti-clearance function.

[0013] Preferably, the eccentric shaft assembly includes an eccentric shaft body, an eccentric shaft bearing and a shock wave bearing, wherein the eccentric shaft bearing is installed on the eccentric section of the eccentric shaft body, and the shock wave bearing is sleeved on the inner side of the shock wave inner ring; the shock wave outer ring is transmission-connected to the eccentric shaft body through the shock wave bearing. In this structure, the eccentric shaft bearing and the shock wave bearing are layered, isolating the input torque fluctuation and making the transmission motion smoother; at the same time, the shock wave inner ring is directly sleeved on the eccentric shaft, simplifying the power transmission path and reducing energy loss.

[0014] Preferably, the outer end faces of the right movable gear rack and the left movable gear rack are respectively provided with shock wave baffles; the shock wave baffles are tightened and fixed by the movable gear rack locking screws to limit the axial displacement of the shock wave. This structure further reduces the axial space occupancy, optimizes the structural redundancy, and improves the assembly reliability.

[0015] Preferably, an annular raceway groove is provided in the axial center of the middle movable gear rack for installing the radial bearing; precision raceways are machined on both side end faces of the middle movable gear rack for installing the end face bearings, thereby avoiding the error in splicing raceways of multiple parts and improving the coaxiality of the main bearing.

[0016] Compared with the prior art, the present invention has the following beneficial effects: By integrating the main bearing raceways originally distributed on the left, right, and center movable gear racks into a single part of the center movable gear rack, the number of key parts has been greatly reduced from 6 to 4, thereby reducing the overall assembly complexity and the difficulty of matching the coaxiality of the parts during machining, while also shortening the manufacturing cycle and reducing manufacturing costs. By adopting a three-row bearing combination structure, namely two rows of axial cylindrical roller thrust bearings and one row of radial cylindrical roller bearings or needle roller bearings, this structure is consistent with the YRT bearings commonly used in CNC turntables. It can ensure high transmission accuracy and stability of the reducer output shaft during rotation, significantly improving the system's positioning and repeatability capabilities; By setting an elastic element with a preset radial deformation H in the shock wave generator and limiting the stiffness of the elastic element, the transmission clearance is first eliminated through elastic deformation during the transmission startup phase. Generally, the required torque is controlled within 10% of the rated torque, which can effectively suppress the initial backlash and avoid additional load caused by the clearance elimination process. It ensures that the rated working torque of the system is not substantially affected, thereby improving the overall load-bearing performance of the reducer.

[0017] By adopting an integrated main bearing and a compact structural design, the reducer of the present invention reduces the axial thickness and overall weight by 10%-20% compared with traditional structures, significantly improving the torque output ratio per unit volume, that is, increasing the torque density, which helps to create a lighter and higher-speed response five-axis machine tool. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a cross-sectional view of an axial section of the present invention; Figure 2 is a cross-sectional view of the present invention; Figure 3 It is a cross-sectional view of the eccentric shaft assembly of the present invention; Figure 4 for Figure 3 Enlarged view of point G in the middle.

[0019] Figure 1: eccentric shaft assembly; 101: eccentric shaft body; 102: eccentric shaft bearing; 103: shock wave bearing; 104: shock wave outer ring; 105: elastic element; 106: shock wave inner ring; 201: movable gear rack pin; 202: movable gear rack locking screw; 203: shock wave assembly spring retaining ring; 204: right movable gear rack; 205: middle movable gear rack; 206: left movable gear rack ; 207, shock wave baffle; 301, inner gear sealing ring; 302, left inner gear ring; 303, inner gear ring connecting pin; 304, inner gear ring connecting screw; 305, inner gear ring spacer; 306, right inner gear ring; 401, movable tooth ring; 402, upper core shaft; 403, K-type assembly; 404, lower core shaft; 501, radial bearing; 502, bearing isolation ring; 503, end bearing. DETAILED DESCRIPTION

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0021] like Figures 1 to 2 As shown, the present application provides a movable tooth reducer that uses a shock wave generator to give a given deformation to eliminate transmission clearance, hereinafter referred to as "the reducer". The reducer includes an eccentric shaft assembly 1, a movable tooth rack assembly, an inner gear ring assembly, a movable tooth assembly and a main bearing assembly.

[0022] See Figure 1 and Figure 2 The eccentric shaft assembly 1 is used to provide input rotation and drive the movable teeth to move, and includes an eccentric shaft body 101, an eccentric shaft bearing 102, and a shock wave bearing 103. The eccentric shaft bearing 102 is mounted on the eccentric section of the eccentric shaft body 101. The movable gear rack assembly is used to carry the movable teeth and transmit torque, and includes a middle movable gear rack 205, a left movable gear rack 206, and a right movable gear rack 204. The right movable gear rack 204 and the left movable gear rack 206 are radially positioned by a movable gear rack pin 201 that penetrates the middle movable gear rack 205. The right movable gear rack 204, the middle movable gear rack 205, and the left movable gear rack 206 are axially fixed by a movable gear rack locking screw 202. The inner gear ring assembly is used to mesh with the movable gear assembly, and includes a left inner gear ring 302, a right inner gear ring 306, and an inner gear ring spacer 305. The left inner gear ring 302 and the right inner gear ring 306 are circumferentially positioned by the inner gear ring connecting pin 303 and axially compressed by the inner gear ring connecting screw 304. The inner gear ring spacer 305 is arranged between the left inner gear ring 302 and the right inner gear ring 306 to control the width of the inner gear ring tooth groove. The movable gear assembly is used to mesh with the inner gear ring to achieve motion conversion, and includes an upper core shaft 402, a lower core shaft 404, a movable gear ring 401, and a K-type component 403. The gear ring is nested in the tooth groove of the movable gear rack assembly, and its inner cavity is sequentially installed with the upper core shaft 402, the K-type component 403, and the lower core shaft 404. The ends of the upper core shaft 402 and the lower core shaft 404 respectively abut the tooth profile curved surface of the inner gear ring. The K-type component 403 is used to provide radial elastic support. The main bearing assembly includes a radial bearing 501 , a bearing spacer 502 and an end bearing 503 .

[0023] Specifically, the radial bearing 501 is a radial cylindrical roller bearing or a needle roller bearing, which is installed in the middle of the middle movable gear frame 205; the end face bearing 503 is two rows of axial cylindrical roller thrust bearings, which are symmetrically distributed on the end faces of both sides of the middle movable gear frame 205; the bearing isolation ring 502 is arranged between the two rows of end face bearings 503 for axial positioning. Since the radial cylindrical roller bearing is arranged in the middle of the middle movable gear frame 205, the total number of parts constituting the main bearing assembly is four, thereby integrating all the main bearing raceways in a single middle movable gear frame 205, which can significantly improve the manufacturing accuracy of the reducer and reduce the axial thickness and weight of the reducer by 10%-20%.

[0024] Furthermore, an annular raceway groove is provided in the axial center of the middle movable gear rack 205 for mounting the radial bearing 501, thereby avoiding the error in splicing the raceways of multiple parts and improving the coaxiality of the main bearing; precision raceways are machined on both side end faces of the middle movable gear rack 205 for mounting the end face bearings 503, thereby eliminating the risk of thermal deformation of traditional bearing seats and ensuring long-term accuracy retention.

[0025] Furthermore, the outer end surfaces of the right movable gear rack 204 and the left movable gear rack 206 are respectively provided with shock wave baffles 207; The shock wave baffle 207 is compressed and fixed by the movable gear frame locking screw 202 to limit the axial displacement of the shock wave.

[0026] See Figure 3 and Figure 4 A shock wave is provided between the eccentric shaft assembly 1 and the movable tooth frame. The shock wave comprises a shock wave outer ring 104, a shock wave inner ring 106 and an annular elastic element 105 located therebetween. The shock wave outer ring 104 is transmission-connected to the eccentric shaft body 101 through a shock wave bearing 103, and is axially limited by a shock wave baffle 207 and a shock wave assembly spring retaining ring 203; the shock wave bearing 103 is sleeved on the inner side of the shock wave inner ring 106, and the elastic element 105 is embedded between the shock wave outer ring 104 and the shock wave inner ring 106, and deformation space is reserved on both sides of the radial direction. The preset deformation amount H is controlled by the thickness of the elastic element 105 and the installation pre-compression amount. The deformation amount H is used to eliminate various gaps in the system, and the stiffness of the elastic element 105 can be given through experiments according to the requirements of the control system. Its upper limit is to keep the working stress of the movable tooth assembly only less than 1 / 10 of the rated stress when the gap H just disappears.

[0027] The specific tasks of this application are as follows: When the system is in an unloaded state, or the output shaft does not bear an external load, the elastic element 105 of the shock wave is in an initial radial compression state due to installation pre-tightening. At this time, the elastic element 105 provides a slight but controlled radial force, so that the gap between the movable tooth assembly and the inner gear ring assembly is compressed and eliminated in advance; this pre-tightening state puts the entire transmission chain in a low backlash state, effectively avoiding the initial dead zone and backlash phenomenon; when the eccentric shaft assembly 1 starts to rotate, its movement drives the shock wave outer ring 104 to rotate through the shock wave and the eccentric shaft bearing 102, and the elastic element 105 in the shock wave structure allows controlled radial elastic deformation to occur between the shock wave outer ring 104 and the inner ring, and the rotational motion is transmitted to the movable tooth assembly through the shock wave structure, driving the movable tooth assembly to perform reciprocating radial motion. At the same time, the upper core shaft 402 in the movable tooth assembly moves along the inner tooth curved surface trajectory of the inner gear ring under the eccentric drive. Due to the internal teeth restriction, the motion is decomposed into: radial swing generated by the eccentric drive and tangential motion that produces actual output torque. The tangential motion pushes the movable tooth carrier assembly through the movable tooth ring 401 to achieve low-speed rotation output, thereby achieving a deceleration effect; When the output shaft is subjected to a certain external load, the elastic element 105 within the shock wave generator is further compressed, and its deformation approaches the set value H. At this point, the radial clearance within the shock wave generator is completely compressed, achieving a zero-clearance, high-rigidity meshing state. By designing the stiffness of the elastic element 105, the torque required for the backlash elimination process does not exceed 10% of the rated operating torque, thereby avoiding weakening the reducer's effective load-bearing capacity.

[0028] The reduction ratio of this reducer is determined by the number of teeth on the movable gear rack. If the number of teeth on the movable gear rack is Z2, then for every rotation of the eccentric shaft, the movable gear rack rotates 1 / Z2 of a circle, achieving a reduction ratio of Z2.

[0029] In order to improve the strength of the movable tooth frame in this application, the design actually adopts the tooth extraction method, retaining only half of the theoretical number of teeth, thereby taking into account both transmission efficiency and structural strength.

[0030] The above content is a detailed description of the present invention in conjunction with specific embodiments, and it cannot be considered that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A movable tooth reducer that uses a shock wave generator to provide a given deformation to eliminate transmission clearance, comprising an eccentric shaft assembly (1), a movable tooth rack assembly, an inner gear ring assembly, a movable tooth assembly, and a main bearing assembly, characterized in that: The eccentric shaft assembly (1) is used to provide input rotation and drive the movable teeth to move; The movable tooth rack assembly comprises a middle movable tooth rack (205), a left movable tooth rack (206) and a right movable tooth rack (204), and is used for carrying movable teeth and transmitting torque; The inner gear ring assembly is provided with fixed inner teeth for engaging with the movable tooth assembly; The movable tooth assembly comprises an upper core shaft (402), a lower core shaft (404), a movable tooth ring (401) and a K-type assembly (403), and is used for meshing with the inner gear ring to realize motion conversion; The main bearing assembly is composed of two rows of axial cylindrical roller thrust bearings and one row of radial cylindrical roller bearings or needle roller bearings, and the radial cylindrical roller bearings are arranged in the middle of the middle movable gear rack (205), so that the total number of parts constituting the main bearing assembly is four, thereby integrating all main bearing raceways into a single middle movable gear rack (205); A shock wave generator is provided between the eccentric shaft assembly (1) and the movable gear frame, and the shock wave generator comprises a shock wave generator outer ring (104), a shock wave generator inner ring (106), and an annular elastic element (105) located therebetween. The elastic element (105) is designed with a preset radial deformation amount H, and is used to eliminate all transmission clearances inside the reducer through radial elastic deformation in the initial stage of driving. The stiffness of the elastic element (105) is set so that the torque required for eliminating the clearance generally does not exceed 10% or other given proportions of the rated torque of the reducer.

2. The movable tooth reducer according to claim 1, which adopts a shock wave device to set a deformation amount to eliminate transmission clearance, is characterized in that: The main bearing assembly comprises a radial bearing (501), a bearing isolation ring (502) and an end bearing (503), wherein: The radial bearing (501) is a radial cylindrical roller bearing or a needle roller bearing, and is installed in the middle of the middle movable gear rack (205); The end face bearings (503) are two rows of axial cylindrical roller thrust bearings, symmetrically distributed on both side end faces of the middle movable gear rack (205); The bearing isolation ring (502) is arranged between two rows of end face bearings (503) and is used for axial positioning.

3. The movable tooth reducer according to claim 1, which adopts a shock wave device to set a deformation amount to eliminate transmission clearance, is characterized in that: The right movable gear rack (204) and the left movable gear rack (206) are radially positioned by a movable gear rack pin (201) penetrating the middle movable gear rack (205); the right movable gear rack (204), the middle movable gear rack (205) and the left movable gear rack (206) are axially fixedly connected by a movable gear rack locking screw (202).

4. The movable tooth reducer according to claim 1, which adopts a shock wave device to set a deformation amount to eliminate transmission clearance, is characterized in that: The inner gear ring assembly comprises a left inner gear ring (302), a right inner gear ring (306) and an inner gear ring spacer (305); the left inner gear ring (302) and the right inner gear ring (306) are circumferentially positioned by an inner gear ring connecting pin (303) and axially compressed by an inner gear ring connecting screw (304); The inner gear ring spacer (305) is arranged between the left inner gear ring (302) and the right inner gear ring (306) and is used to control the inner gear ring tooth groove width.

5. The movable tooth reducer according to claim 1, which adopts a shock wave device to set a deformation amount to eliminate transmission clearance, is characterized in that: The movable tooth ring (401) is nested in the tooth groove of the movable tooth frame assembly, and the upper core shaft (402), the K-type assembly (403) and the lower core shaft (404) are installed in the inner cavity of the movable tooth ring in sequence; The ends of the upper core shaft (402) and the lower core shaft (404) respectively abut against the tooth profile curved surface of the inner gear ring, and the K-type component (403) is used to provide radial elastic support.

6. The movable tooth reducer according to claim 1, which adopts a shock wave device to set a deformation amount to eliminate transmission clearance, is characterized in that: The elastic element (105) is embedded between the shock wave outer ring (104) and the shock wave inner ring (106); Deformation space is reserved on both radial sides of the elastic element (105), and a preset deformation amount H thereof is controlled by the thickness of the elastic element (105) and the amount of pre-compression during installation; The shock wave outer ring (104) is axially limited by the shock wave baffle (207) and the shock wave assembly spring clamp (203).

7. The movable tooth reducer according to claim 1, which adopts a shock wave device to set a deformation amount to eliminate transmission clearance, is characterized in that: The eccentric shaft assembly (1) comprises an eccentric shaft body (101), an eccentric shaft bearing (102) and a shock wave generator bearing (103), wherein: The eccentric shaft bearing (102) is mounted on the eccentric section of the eccentric shaft body (101); the shock wave bearing (103) is sleeved on the inner side of the shock wave inner ring (106); and the shock wave outer ring (104) is transmission-connected to the eccentric shaft body (101) via the shock wave bearing (103).

8. The movable tooth reducer according to claim 3, which adopts a shock wave device to set a deformation amount to eliminate transmission clearance, is characterized in that: The outer end surfaces of the right movable gear rack (204) and the left movable gear rack (206) are respectively provided with shock wave baffles (207); The shock wave baffle (207) is pressed and fixed by the movable gear frame locking screw (202) to limit the axial displacement of the shock wave.

9. The movable tooth reducer according to claim 1, which adopts a shock wave device to set a deformation amount to eliminate transmission clearance, is characterized in that: An annular raceway groove is provided in the axial center of the middle movable gear rack (205) for mounting the radial bearing (501); and precision raceways are machined on both side end faces of the middle movable gear rack (205) for mounting the end face bearings (503).

Images