Lightweight steering gear with harmonic reducer

Abstract

The present application relates to a kind of light rudder machine of mounting harmonic reducer, including mutually buckling front shell (10) and rear shell (1), motor and harmonic reducer are arranged in front shell (10) and rear shell (1);Cam (4) of harmonic reducer one end is driven synchronous pulley, driven synchronous pulley is combined with the driving pulley (15) on motor (14) by synchronous belt (5);Cam (4) other end coaxially connects and sets up elliptical cam, and elliptical cam is formed wave generator with the flexible bearing (7) of external nesting arrangement and located in the inner wall of flexible gear (9).Lightweight, small, space is compact, arrangement is reasonable to guarantee the sealing and integrity of rudder, assembly production is convenient, and reliability is high.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of service robots, gimbals, high-end toys and automatic control, and particularly relates to a light-weight steering engine carrying a harmonic reducer. BACKGROUND

[0002] Traditional harmonic reducers have the advantages of compact structure, small volume, light weight, large carrying capacity, small backlash and high transmission precision, and are widely used in industrial robots, aerospace and precision machine tool fields. The harmonic reducer is composed of a steel wheel, a flexible wheel and a wave generator. The wave generator with elliptical deformation is installed inside the flexible wheel with elasticity. The wave generator rotates to force the flexible wheel tooth profile and the steel wheel tooth profile to periodically mesh and separate, thereby realizing the effect of staggered tooth difference reduction.

[0003] However, the traditional harmonic reducer has the following problems in the application of the steering engine:

[0004] 1. The traditional harmonic reducer is generally made of metal, so the quality of such a reduction steering engine product is larger.

[0005] 2. In order to ensure the deformation of the metal, the flexible wheel has a certain length in the axial direction, which makes the volume of the harmonic reducer relatively large and the performance is affected.

[0006] 3. The traditional harmonic reducer and the steering engine containing the same are limited in shape design due to the processing performance of the metal. The heat treatment process is not as flexible as injection molding products. SUMMARY

[0007] The technical problem to be solved by the present application is to overcome the above technical problems in the prior art, and to provide a light-weight steering engine carrying a harmonic reducer, which improves the defect that the flexible wheel of the traditional harmonic reducer has a certain length in the axial direction in order to ensure the deformation of the metal, thereby making the volume of the harmonic reducer relatively large and the performance is affected. Lightweight, small volume, compact space, reasonable arrangement to ensure the sealing and integrity of the steering engine, easy assembly and production, high reliability.

[0008] To solve the above technical problems, the application adopts the following technical solutions:

[0009] The application discloses a light-weight rudder with a harmonic reducer, which is characterized by comprising a front shell (10) and a rear shell (1) which are buckled with each other, a motor and a harmonic reducer arranged in the front shell (10) and the rear shell (1); one end of a cam (4) of the harmonic reducer is a driven synchronous pulley, the driven synchronous pulley is combined with a driving pulley (15) on the motor (14) through a synchronous belt (5); the other end of the cam (4) is coaxially connected with an elliptical cam, the elliptical cam forms a wave generator together with a flexible bearing (7) which is arranged in a nested mode outside, and is located in the inner wall of a flexible gear (9); the outer ring teeth of the flexible gear (9) and the inner ring teeth of a steel gear (8) are periodically engaged or separated in the rotating process of the wave generator; the flexible gear (9), the steel gear (8) and the cam (4) are all formed by injection molding of engineering plastics.

[0010] Further, the cam (4) is a two-stage stepped cam, the smaller stepped end is an elliptical cam, and the flexible bearing (7) is arranged in a nested mode outside the elliptical cam; the larger stepped end of the cam (4) is provided with a tooth surface on the outer periphery to form a driven synchronous pulley, and the driven synchronous pulley is engaged with the synchronous belt (5).

[0011] Further, the top of one end of the cam (4) provided with the driven synchronous pulley is fixed with a synchronous belt retainer ring (3), and the inner space of one end of the cam (4) provided with the elliptical cam is provided with a balance bearing (6).

[0012] Further, the output shaft (12) is designed as a long shaft, the flexible gear (9) is fixed to the outer wall of one end of the front shell (10) combined with the output shaft (12), the outer side of the flexible gear (9) is an output mounting flange, and the output mounting flange is flush with the end surface of the front shell (10) on the outer periphery of the output shaft (12).

[0013] Further, the output shaft (12) is provided with a counterbore at one end facing the rear shell (1), a position magnetic steel (16) is arranged in an interference fit position in the counterbore, and an auxiliary bearing (2) is arranged on the outer shaft of the counterbore, the auxiliary bearing (2) is fixed between the output shaft (12) and the inner wall of the central hole of the output shaft (12) of the rear shell (1); a position sensor (17) is further arranged on the rear shell (1) corresponding to the position magnetic steel (16).

[0014] Further, the steel gear (8) is clamped on the step between the front shell (10) and the rear shell (1) in the axial direction, and the bottom cover of the flexible gear (9) and the output shaft (12) are rigidly fixed together; a supporting bearing (11) is arranged between the front shell (10) and the output shaft (12), and the supporting bearing (11) is arranged in an interference fit mode on the end surface of the front shell (10) on the outer periphery of the output shaft (12).

[0015] Further, the tooth shapes of the flexible gear (9) and the steel gear (8) are both C-shaped teeth.

[0016] Further, the steel wheel (8) and the cam (4) are injection molded by PPS+10% or more carbon fiber; the flexible wheel (9) is injection molded by POM or PA or PPS or PEEK or other material adding carbon fiber or PTFE or molybdenum disulfide.

[0017] Further, the front shell (10) and the rear shell (1) are injection molded by PPS or PC adding 10% or more carbon fiber or glass fiber.

[0018] Therefore, the light steering engine provided by the application carries the special plastic harmonic reducer mechanism, the flexible wheel, the steel wheel and the cam of the plastic harmonic reducer mechanism are injection molded by special engineering plastic, the tooth profile C tooth profile is designed to ensure the transmission torque and rigidity of the plastic reducer, the driving motor of the light steering engine drives the driven synchronous pulley integrated with the cam to rotate through the driving synchronous pulley installed on the motor output shaft, the cam rotation promotes the wave generation work, and the harmonic reducer operates.

[0019] Compared with the existing harmonic reducer mechanism and the light steering engine, the application has the following beneficial effects:

[0020] The assembly is convenient, and many connecting parts such as screws can be omitted, so that the weight is further reduced.

[0021] The structure of the application has a unique assembly method, reduces the assembly difficulty, prevents mistakes, and is convenient to manufacture.

[0022] The harmonic reducer includes a non-metallic shell, and the quality of the speed steering engine product is smaller.

[0023] The flexible wheel of the harmonic reducer is a non-metallic material, and the deformation amount of the metal does not need to be considered, the length of the flexible wheel in the axial direction is controlled to be flat, and the length is smaller than that of the metal flexible wheel.

[0024] Considering the non-metallic property of the shell, the steel wheel and the cam, the product shape design and process are more flexible than the metal processing process, and the processing performance is better than that of the traditional metal harmonic reducer and the steering engine. BRIEF DESCRIPTION OF DRAWINGS

[0025] Fig. 1 It is a structure schematic view (perspective view) of the light steering engine carrying the harmonic reducer according to the embodiment of the application.

[0026] Fig. 2The schematic diagram of the transmission part structure of the light rudder of the present application with a harmonic reducer (after removing the rear shell 1).

[0027] Fig. 3 The schematic diagram of the internal structure of the light rudder of the present application with a harmonic reducer.

[0028] Figs. 1-3 The accompanying drawings are as follows: 1. rear shell; 2. auxiliary bearing; 3. synchronous belt stop ring; 4. cam; 5. synchronous belt; 6. balance bearing; 7. flexible bearing; 8. steel wheel; 9. flexspline; 10. front shell; 11. support bearing; 12. output shaft; 13. flexspline gasket; 14. motor; 15. driving pulley; 16. position magnet; 17. position sensor. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0030] ATTACHMENT Figs. 1-3 In the present application, the light rudder with a harmonic reducer includes a front shell 10 and a rear shell 1 that are buckled together, and the front shell 10 and the rear shell 1 are assembled into an integrated light rudder by self-tapping screws, which ensures the sealing and integrity of the rudder and facilitates assembly and production, and has high reliability.

[0031] The motor 14 and the harmonic reducer arranged in parallel with the shaft of the motor 14 are placed in the two shells; the harmonic reducer includes a flexspline 9, a steel wheel 8 and a wave generator including a cam 4 in the flexspline 9. The motor 14 and the harmonic reducer are arranged in parallel, which is compact in space and reasonable in arrangement.

[0032] The outer ring of the flexspline 9 and the inner ring of the steel wheel 8 are periodically engaged and separated in tooth shape, which realizes the effect of staggered tooth difference reduction.

[0033] In the interior of the flexspline 9, a wave generator including the cam 4 is arranged. The cam 4 is a two-stage stepped cam, the smaller stepped end of which is an elliptical cam, and the elliptical cam is nested and installed with a flexible bearing 7, which is installed on the inner ring of the flexspline 9. The inner ring of the flexspline 9 is provided with a limit stop ring, which can control the axial position of the flexible bearing 7. The outer periphery of the larger stepped end of the cam 4 is provided with a tooth surface to form a driven synchronous pulley, which is engaged with the synchronous belt 5; the end of the driven pulley of the cam 4 is fixed with a synchronous belt stop ring 3 by self-tapping screws, which can limit the axial movement of the synchronous belt 5.

[0034] The flexible bearing 7 is installed on the inner ring of the flexspline 9 and is located between the flexspline 9 and the outer wall of the elliptical cam, the inner ring of the flexspline 9 is provided with a limit stop ring, which can control the axial position of the flexible bearing 7. The bottom cover of the flexspline 9 and the output shaft 12 are rigidly fixed together by self-tapping screws. The steel wheel 8 is provided with a limit groove, which is tightly fitted and fixed with the positioning hole and the positioning rib of the front shell 10, and the support bearing 11 is installed in interference fit with the front shell 10.

[0035] The balance bearing 6 is arranged between the inner shaft hole of the elliptical cam and the output shaft 12, and the balance bearing 6 is located in the inside of the corresponding cam 4. The inner ring of the balance bearing 6 is fixed on the output shaft 12, and the output shaft 12 is arranged in parallel with the output shaft of the motor 14.

[0036] The output shaft 12 passes through the inner central hole of the front shell 10, and the support bearing 11 is arranged between the front shell 10 and the output shaft 12 to limit the axial position. The output shaft 12 adopts a long shaft design, one end of the output shaft 12 combined with the front shell 10 is an output mounting flange, and the other end is provided with a counterbore, the counterbore is in interference fit with the position magnetic steel 16, and the outer shaft of the counterbore is provided with an auxiliary bearing 2. Correspondingly, the auxiliary bearing 2 is arranged between the side wall of the central hole of the rear shell 1 and the outer shaft of the counterbore, and the mounting hole of the auxiliary bearing 2 is arranged on the side wall of the central hole of the rear shell 1. The rear shell 1 is provided with a fixing hole corresponding to the output shaft, which is used for fixing the position sensor 17.

[0037] The motor 14 is installed on the motor mounting seat of the front shell 10, and the driving pulley 15 is in interference fit with the output shaft of the motor 14. The motor 14 drives the synchronous belt 5 through the driving pulley 15 to drive the driven pulley on the cam 4 to rotate. The driving pulley 15 is enclosed in the rear shell 1 and is arranged in space with the inner wall of the top of the rear shell 1.

[0038] In order to realize light weight, the flexspline, the steel wheel and the cam of the harmonic reducer mechanism of the application are all made of special engineering plastics by injection molding. In order to ensure the transmission torque and rigidity of the plastic reducer, the tooth shape of the flexspline and the steel wheel adopts C tooth shape design. The tooth shape of the steel wheel is formed by the motion envelope of the tooth shape of the flexspline. The tooth height ratio of the C tooth shape is 30% higher than that of the involute tooth shape or the circular arc tooth shape. The meshing ratio of the C tooth shape is 50% higher than that of the involute tooth shape or the circular arc tooth shape.

[0039] The addendum arc radius of the C tooth shape is smaller than that of the involute tooth shape or the circular arc tooth shape, and the dedendum arc radius is larger than that of the involute tooth shape or the circular arc tooth shape.

[0040] The cam profile of the wave generator adopts an elliptical contour, the major axis and the minor axis of the ellipse are determined according to the speed ratio and the gear modulus of the harmonic reducer, and the polar equation of the elliptical curve is , wherein a and b are the lengths of the major axis and the minor axis of the elliptical curve, As the polar axis, It is the polar angle.

[0041] The process of determining the tooth profile of the flexspline C is as follows:

[0042] First, assume the flexible gear tooth profile adopts a circular arc tooth profile, and the polar coordinate equation of the tooth profile is: In the formula ( , ( ) represents the polar coordinates of the center point of the circle. R The radius is the radius of the circle. This is derived from the elliptical profile of the cam. Then, its asymptote S can be obtained using differential geometry, where... This tapering curve is a cam-shaped curve. The envelope of the normal family, through coordinate transformation, gives the polar coordinate equation of the tooth profile of the flexible gear tooth. with the gradient By approximating the fit and considering the addendum circle diameter, root circle diameter, and pitch circle diameter of the flexure, the C-tooth profile of the flexure is finally determined. Based on the rotation law of the wave generator and the deformation of the C-tooth profile of the flexure, the envelope of the flexure tooth profile is obtained through finite element analysis, and the tooth profile of the steel wheel is drawn.

[0043] Furthermore, the engineering plastic substrate can be at least one of nylon, POM, PAI, and PEEK, or one of carbon fiber, glass fiber, graphite, PTFE, and molybdenum disulfide can be added to the substrate.

[0044] Furthermore, the steel wheel 8 and the cam 4 are injection molded using PPS with more than 10% carbon fiber; the flexible wheel 9 is injection molded using POM, PA, PPS, or PEEK as the base material with added carbon fiber, PTFE, or molybdenum disulfide.

[0045] The front housing 10 and the rear housing 1 are injection molded using PPS or PC with more than 10% carbon fiber or glass fiber.

[0046] Thus, motor 14 drives drive pulley 15, which in turn drives driven synchronous pulley on cam 4 via synchronous belt 5. A flexible bearing 7 is mounted on cam 4, forming a wave generator. The wave generator is installed inside a flexible flexure 9. The rotation of the wave generator forces the teeth of flexure 9 to periodically mesh and separate from the teeth of steel wheel 8, thereby achieving a tooth-shifting speed reduction effect. Flexure 9 is fixed to output shaft 12, which is coaxial. A position magnet 16 is mounted at the end of output shaft 12, forming a closed-loop position and speed control system with position sensor 17 for the lightweight servo motor.

[0047] It should be noted that the various steps / components described in the present application can be split into more steps / components or two or more steps / components or parts of the operation of steps / components can be combined into new steps / components, as required by implementation, to achieve the objectives of the present application.

[0048] Those skilled in the art will easily understand that the above description is only the preferred embodiment of the present application and is not intended to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A lightweight servo motor equipped with a harmonic reducer, characterized in that: The device includes a front housing (10) and a rear housing (1) that interlock with each other, and a motor (14) and a harmonic reducer are installed in the front housing (10) and the rear housing (1). The output shaft (12) of the harmonic reducer and the output shaft of the motor (14) are arranged in parallel. One end of the cam (4) of the harmonic reducer is a driven synchronous pulley, which is connected to the driving pulley (15) on the motor (14) through a synchronous belt (5). The other end of the cam (4) is coaxially connected to an elliptical cam, which forms a wave generator with the externally nested flexible bearing (7) and is located inside the inner wall of the flexible wheel (9). The outer ring teeth of the flexible wheel (9) and the inner ring teeth of the steel wheel (8) are in the wave generator. The device engages or disengages periodically during rotation; the flexible wheel (9), steel wheel (8), and cam (4) are all injection molded from engineering plastics; the bottom cover of the flexible wheel (9) and the output shaft (12) are rigidly fixed together; inside the flexible wheel (9), a wave generator including the cam (4) is installed; the flexible bearing (7) is installed on the inner ring of the flexible wheel (9) and located between the flexible wheel (9) and the outer wall of the elliptical cam; the output shaft (12) adopts a long shaft design, and the flexible wheel (9) is fixed on the outer wall of one end that is connected to the front housing (10). The outer side of the flexible wheel (9) is the output mounting flange, which is flush with the end face of the front housing (10) around the output shaft (12).

2. The lightweight servo motor equipped with a harmonic reducer according to claim 1, characterized in that: Cam (4) is a two-stage stepped cam. The smaller step end is an elliptical cam, and a flexible bearing (7) is nested on the outside of the elliptical cam. The larger step end of cam (4) is provided with a toothed surface to form a driven synchronous pulley, which meshes with the synchronous belt (5).

3. The lightweight servo motor equipped with a harmonic reducer according to claim 2, characterized in that: The cam (4) has a timing belt retainer (3) fixed at the top of one end of the driven timing belt pulley. The cam (4) has a balance bearing (6) installed in the internal space of one end of the elliptical cam. The inner ring of the balance bearing (6) is fixed on the output shaft (12).

4. The lightweight servo motor equipped with a harmonic reducer according to claim 1, characterized in that: The output shaft (12) has a countersunk hole at one end facing the rear housing (1), and a position magnet (16) is interference-fitted inside the countersunk hole. An auxiliary bearing (2) is installed on the outer shaft of the countersunk hole. The auxiliary bearing (2) is fixed between the output shaft (12) and the inner wall of the center hole of the output shaft (12) of the rear housing (1). A position sensor (17) is also provided on the rear housing (1) corresponding to the position magnet (16).

5. The lightweight servo motor equipped with a harmonic reducer according to claim 1, characterized in that: The steel wheel (8) is axially mounted on the step between the front housing (10) and the rear housing (1); a support bearing (11) is provided between the front housing (10) and the output shaft (12), and the support bearing (11) is installed with the front housing (10) in an interference fit and located in the end face of the front housing (10) outside the output shaft (12).

6. The lightweight servo motor equipped with a harmonic reducer according to claim 1, characterized in that: Both the flexible wheel (9) and the steel wheel (8) have C-shaped teeth.

7. The lightweight servo motor equipped with a harmonic reducer according to claim 1, characterized in that: The steel wheel (8) and the cam (4) are injection molded with PPS and more than 10% carbon fiber; the flexible wheel (9) is injection molded with carbon fiber, PTFE or molybdenum disulfide as the base material, using POM or PA or PPS or PEEK as the base material.

8. The lightweight servo motor equipped with a harmonic reducer according to claim 1, characterized in that: The front housing (10) and the rear housing (1) are injection molded using PPS or PC with more than 10% carbon fiber or glass fiber.

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