A precision reducer based on cam-gear combined drive

Abstract

The present invention discloses a precision reducer based on cam-gear combined drive, comprising: a base, an input end ball bearing, a cylindrical cam, a planar groove cam, a swing rod, a piece tooth, a piece tooth assembly, a deep groove ball bearing, an output gear, an output end ball bearing, and an upper end cover. The precision reducer based on cam-gear combined drive is a two-stage reduction. The first-stage reduction occurs between the planar groove cam and the swing rod, and the second-stage reduction occurs between the swing rod and the piece tooth. Based on the cam drive principle and the gear meshing drive principle, the present invention proposes an innovative principle of cam-gear combined drive, and through the innovative internal structure, greatly improves the situation that the contact area between gears in the traditional gear train is very small, and increases the contact points and lines as much as possible during the transmission process, so that the combined stress borne by each tooth is greatly reduced. The present invention has a large reduction ratio, can transmit a large torque, and meets the requirements of industrial robot joint reducers in the market.

Description

Technical Field

[0001] The present invention relates to the technical field of speed reducers, and in particular to a precision speed reducer, and more particularly to a precision speed reducer based on a cam-gear combined drive. Background Art

[0002] A speed reducer is an intermediate device connecting a power source and an actuator. The transmission system of a traditional speed reducer usually includes multiple gears with different parameters, such as different sizes, quantities, and types of teeth, such as spur gears, helical gears, turbines, internal gears, etc. The contact in a traditional gear train is usually a point or a line on the tooth, which results in a very small contact area, while the amount of power to be transmitted is large. Therefore, the stress along the contact point or contact line is very high.

[0003] Currently, the mature and standardized speed reducers are: cylindrical gear speed reducers, turbine speed reducers, planetary speed reducers, RV speed reducers, cycloidal pinwheel speed reducers, and harmonic speed reducers. Among them, the precision speed reducers widely used in the joints of industrial robots are RV speed reducers and harmonic speed reducers. Industrial robots are widely used in various industrial fields such as electronics, logistics, and chemical industry. To ensure that industrial robots can reliably complete process tasks and ensure process quality, high requirements are imposed on the positioning accuracy and repeat positioning accuracy of the robots. Therefore, precision speed reducers are crucial for industrial robots.

[0004] The RV speed reducer is a two-stage enclosed planetary drive mechanism with a low tooth difference developed on the basis of a cycloidal pinwheel. Due to the relatively large number of components and complex structure of the RV speed reducer, and extremely high manufacturing precision requirements between components, the product qualification rate is relatively low. A harmonic speed reducer is a drive that relies on a wave generator to cause the flexible gear to generate controllable elastic deformation to achieve motion and power transmission. The harmonic speed reducer mainly includes a wave generator, a flexible gear, and a rigid gear. Among them, the flexible gear is a thin-walled cylinder. Due to structural limitations, the cylinder length of the flexible gear is generally large, resulting in a relatively large overall axial dimension of the harmonic speed reducer. Summary of the Invention

[0005] In view of the meshing transmission of multiple gears used in the transmission system of traditional speed reducers, the present invention proposes an innovative principle of cam-gear combined drive based on the cam drive principle and the gear meshing drive principle, and through an innovative internal structure, greatly improves the situation of very small contact area between gears in a traditional gear train, increasing the number of contact points and lines as much as possible during the transmission process, so that the combined stress on each tooth is greatly reduced. In addition, the structure of the present invention is simple, compact, small in size, has a large reduction ratio, and can transmit a large torque, meeting the requirements of industrial robot joint speed reducers in the market.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A precision reducer based on cam-gear combined drive, comprising: a base, an input end ball bearing, a cylindrical cam, a planar groove cam, a swing rod, a flake tooth, a flake tooth assembly, a deep groove ball bearing, an output gear, an output end ball bearing, and an upper end cover. This precision reducer based on cam-gear combined drive is a two-stage reduction. The first-stage reduction occurs between the planar groove cam and the swing rod, and the second-stage reduction occurs between the swing rod and the flake tooth.

[0008] The input end ball bearing is an angular contact ball bearing, in hole-basis fit with the cylindrical cam and in shaft-basis fit with the base, and the axial movement of the bearing is restricted by the base and the cylindrical cam to unidirectionally fix both ends of the input end ball bearing.

[0009] The cylindrical cam and the planar groove cam are connected together by bolts, and both transmit power and motion through the input shaft. The lower end of the cylindrical cam is in hole-basis fit with the input end ball bearing, and the upper end is in shaft-basis fit with the deep groove ball bearing. The cylindrical cam controls the axial movement of the flake tooth by rotating around the central axis.

[0010] For the planar groove cam, the groove of the cam is divided into two sections, and the planar groove cam makes the swing rod perform a push stroke - return stroke movement by rotating around the central axis.

[0011] The swing rod is fixed on the upper end cover. The lower end of the swing rod is spherical and is matched with the groove of the planar groove cam, and makes a push stroke - return stroke movement as the planar groove cam rotates. The top surface of the upper end is an arc surface, and the two side surfaces are involute surfaces, which are meshed with the flake tooth to drive the flake tooth to make a reciprocating swing.

[0012] The two side surfaces of the slot opening where the flake tooth is matched with the swing rod are conjugate involute surfaces, and the bottom surface is an arc. In addition, the flake tooth and the output gear are meshed with each other to transmit motion and power, just like the inner and outer gear rings are meshed with each other, which greatly increases the contact points or lines. When multiple flake teeth and the output gear are meshed and transmitted, the combined stress on the output gear and the flake tooth will be greatly reduced.

[0013] The flake tooth assembly and the flake tooth are in threaded fit. The lower end of the flake tooth assembly is spherical and is matched with the groove of the cylindrical cam. The rotation of the cylindrical cam drives the flake tooth assembly to move along the groove to realize the axial movement of the flake tooth and the flake tooth assembly.

[0014] The deep groove ball bearing is in hole-basis fit with the output gear and in shaft-basis fit with the upper end of the cylindrical cam, and the axial movement of the bearing is restricted by the cylindrical cam and the output gear to unidirectionally fix both ends of the deep groove ball bearing.

[0015] The lower end of the output gear is in hole-basis fit with the deep groove ball bearing, and the upper end is in hole-basis fit with the output end ball bearing. The output gear transmits motion and power through the flake tooth and outputs outward through the upper flange.

[0016] The output end ball bearing mentioned above is an angular contact ball bearing, which is in a basic shaft system fit with the upper end cover and a basic hole system fit with the output gear. The axial movement of the bearing is restricted by the output gear and the upper end cover, and the two ends of the output end ball bearing are fixed unidirectionally.

[0017] The kinematic relationships of the important components of the present invention are as follows: The input shaft drives the cylindrical cam and the planar groove cam to rotate together. The lower end of the swing rod makes a forward stroke - return stroke movement along the groove of the planar groove cam, and the upper end makes a reciprocating swing, thereby driving the piece teeth to make a reciprocating movement. At the same time, the piece teeth move axially along the groove of the cylindrical cam, periodically engaging and disengaging the output gear, and the output gear transmits motion and power through the piece teeth.

[0018] The working principle of the present invention is as follows: When the cylindrical cam and the planar groove cam rotate together, the lower end of a swing rod makes a forward stroke movement, and the upper end drives the piece teeth to rotate around the central axis of the output gear through meshing transmission, and the piece teeth transmit motion and power to the output gear; before the lower end of the swing rod makes a return stroke movement, the piece tooth assembly moves axially along the groove of the cylindrical cam, driving the piece teeth to disengage from the output gear. At this time, the motion of the output gear is transmitted through other piece teeth; when the lower end of the swing rod makes a return stroke movement, the upper end of the swing rod drives the piece teeth to make a rotation around the central axis of the output gear opposite to the motion of the output gear. At this time, the motion of the output gear is still transmitted through other piece teeth; when the planar groove cam rotates one week and the lower end of the swing rod is about to start making a forward stroke movement again, the piece tooth assembly moves axially along the groove of the cylindrical cam, driving the piece teeth to engage with the output gear. During the whole motion process, the output gear only rotates one tooth. In this way, when the planar groove cam and the cylindrical cam rotate one week, the output gear only rotates one tooth, thereby realizing a large reduction ratio transmission.

[0019] Due to the adoption of the above - mentioned technical solution, the present invention has the following beneficial effects:

[0020] 1. A new type of precision reducer breaks the multiple - gear meshing transmission used in traditional reducers, combines cams and gears ingeniously, and has a brand - new transmission principle.

[0021] 2. A new type of precision reducer greatly improves the synthetic stress on the teeth of each gear caused by the small contact area of the teeth in traditional reducers. Compared with traditional gear trains, the working life of the gears is longer.

[0022] 3. A new type of precision reducer, compared with the commonly used industrial robot joint precision reducers at present, while being simple and compact in structure and small in size, can transmit a larger torque, realize a large reduction ratio transmission, and can meet the requirements of industrial robot joints for high - precision reducers. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Structural diagram of the new type of precision reducer.

[0024] Figure 2 Cylindrical cam part drawing.

[0025] Figure 3 Plane groove cam part drawing.

[0026] Figure 4 Tooth segment assembly part drawing.

[0027] Figure 5 Tooth segment part drawing.

[0028] Figure 6 Rocking bar part drawing.

[0029] Figure 7 Output gear part drawing.

[0030] Notes in the figure: 1 bolt, 2 base, 3 input end ball bearing, 4 cylindrical cam, 5 plane groove cam, 6 screw, 7 deep groove ball bearing, 8 rocking bar, 9 tooth segment assembly, 10 tooth segment, 11 output gear, 12 output end ball bearing, 13 upper end cover, 14 screw. Specific implementation mode

[0031] Referring to the attached drawings, a new type of precision reducer includes: base 2, input end ball bearing 3, cylindrical cam 4, plane groove cam 5, rocking bar 8, tooth segment 10, tooth segment assembly 9, deep groove ball bearing 7, output gear 11, output end ball bearing 12, upper end cover 13. The new type of precision reducer is a two-stage reduction type. The first-stage reduction occurs between the plane groove cam and the rocking bar, and the second-stage reduction occurs between the rocking bar and the tooth segment.

[0032] Referring to the attached drawings, the base 2 is connected to the upper end cover 13 by screws 14. The input end ball bearing 3 is an angular contact ball bearing, with a hole-basis fit with the cylindrical cam 4, a shaft-basis fit with the base 2, and the axial movement of the bearing is restricted by the base 2 and the cylindrical cam 4 to unidirectionally fix both ends of the input end ball bearing 3. The cylindrical cam 4 and the planar groove cam 5 are connected together by screws 6, and power and motion are transmitted between them through the input shaft. The lower end of the cylindrical cam 4 has a hole-basis fit with the input end ball bearing 3, and the upper end has a shaft-basis fit with the deep groove ball bearing 7. The cylindrical cam 4 controls the axial movement of the flapper teeth 10 by rotating around the central axis. The groove of the planar groove cam 5 is divided into two sections. The planar groove cam 5 rotates around the central axis to make the swing rod 8 perform a forward stroke - return stroke motion. The swing rod 8 is fixed to the upper end cover 13. The lower end of the swing rod 8 is spherical and mates with the groove of the planar groove cam 5, performing a forward stroke - return stroke motion as the planar groove cam 5 rotates. The upper top surface is an arc surface, and the two side surfaces are involute surfaces, which mesh with the flapper teeth 10 to drive the flapper teeth 10 to perform reciprocating swings. The two side surfaces of the slot where the flapper teeth 10 mates with the swing rod 8 are conjugate involute surfaces, and the bottom surface is an arc. In addition, the flapper teeth 10 mesh with the output gear 11 to transmit motion and power, similar to the meshing of internal and external gear rings, greatly increasing the contact points or lines. When multiple flapper teeth 10 and the output gear 11 mesh and transmit power, the combined stress on the output gear 11 and the flapper teeth 10 will be greatly reduced. The flapper teeth assembly 9 and the flapper teeth 10 are in threaded fit. The lower spherical part of the flapper teeth 10 assembly mates with the groove of the cylindrical cam 4, and the rotation of the cylindrical cam 4 drives the flapper teeth assembly 9 to move along the groove, realizing the axial movement of the flapper teeth 10 and the flapper teeth assembly 9. The deep groove ball bearing 7 has a hole-basis fit with the output gear 11, a shaft-basis fit with the upper end of the cylindrical cam 4, and the axial movement of the deep groove ball bearing 7 is restricted by the cylindrical cam 4 and the output gear 11 to unidirectionally fix both ends of the deep groove ball bearing 7. The lower end of the output gear 11 has a hole-basis fit with the deep groove ball bearing 7, and the upper end has a hole-basis fit with the output end ball bearing 12. The output gear 11 transmits motion and power through the flapper teeth 10 and outputs it outward through the upper flange. The output end ball bearing 12 is an angular contact ball bearing, with a shaft-basis fit with the upper end cover 13, a hole-basis fit with the output gear 11, and the axial movement of the bearing is restricted by the output gear 11 and the upper end cover 13 to unidirectionally fix both ends of the output end ball bearing 12.

[0033] The motion relationships of the important components of the present invention are as follows: The input shaft drives the cylindrical cam 4 and the planar groove cam 5 to rotate together. The lower end of the swing rod 8 performs a forward stroke - return stroke motion along the groove of the planar groove cam 5, and the upper end performs a reciprocating swing, thereby driving the flapper teeth 10 to perform a reciprocating motion. At the same time, the flapper teeth 10 move axially along the groove of the cylindrical cam 4, periodically engaging and disengaging the output gear 11, and the output gear 11 transmits motion and power through the flapper teeth 10.

[0034] The working principle of the present invention is as follows: When the cylindrical cam 4 and the planar groove cam 5 rotate together, the lower end of a swing rod 8 performs a forward stroke motion, and the upper end drives the fluted teeth 10 to rotate around the central axis of the output gear 11 through meshing transmission. The fluted teeth 10 transmit motion and power to the output gear 11; before the lower end of the swing rod 8 performs a return stroke motion, the fluted tooth assembly 9 performs an axial motion along the groove of the cylindrical cam 4, driving the fluted teeth 10 to separate from the output gear 11. At this time, the motion of the output gear 11 is transmitted through other fluted teeth 10; when the lower end of the swing rod 8 performs a return stroke motion, the upper end of the swing rod 8 drives the fluted teeth 10 to rotate around the central axis of the output gear 11 in a direction opposite to the motion of the output gear 11. At this time, the motion of the output gear 11 is still transmitted through other fluted teeth 8; when the planar groove cam 5 rotates one week and the lower end of the swing rod 8 is about to start performing a forward stroke motion again, the fluted tooth assembly 9 performs an axial motion along the groove of the cylindrical cam 4, driving the fluted teeth 10 to engage with the output gear 11. During the entire motion process, the output gear 11 only rotates one tooth. In this way, the cycle repeats. Whenever the planar groove cam 5 and the cylindrical cam 4 rotate one week, the output gear 11 only rotates one tooth, thereby achieving a large reduction ratio transmission.

Claims

1. A precision reducer based on cam-gear combined drive, characterized in that, it includes: a base, an input end ball bearing, a cylindrical cam, a planar groove cam, a swing rod, a flake tooth, a flake tooth assembly, a deep groove ball bearing, an output gear, an output end ball bearing and an upper end cover; this precision reducer based on cam-gear combined drive is a two-stage reduction; the first-stage reduction occurs between the planar groove cam and the swing rod, and the second-stage reduction occurs between the swing rod and the flake tooth; The input end ball bearing is an angular contact ball bearing, has a hole-basis fit with the cylindrical cam, has a shaft-basis fit with the base, and restricts the axial movement of the bearing through the base and the cylindrical cam, and fixes the two ends of the input end ball bearing unidirectionally; The cylindrical cam and the planar groove cam are connected together by bolts, and both transmit power and motion through the input shaft. The lower end of the cylindrical cam has a hole-basis fit with the input end ball bearing, and the upper end has a shaft-basis fit with the deep groove ball bearing. The cylindrical cam controls the axial movement of the flake tooth by rotating around the central axis; For the planar groove cam, the groove of the cam is divided into two sections, and the planar groove cam makes the swing rod perform a push stroke - return stroke movement by rotating around the central axis; The swing rod is fixed on the upper end cover. The lower end of the swing rod is spherical and is matched with the groove of the planar groove cam, and makes a push stroke - return stroke movement as the planar groove cam rotates. The upper end top surface is an arc surface, and the two side surfaces are involute surfaces, which mesh and drive with the flake tooth to drive the flake tooth to make a reciprocating swing; The two side surfaces of the notch of the flake tooth that cooperates with the swing rod are conjugate involute surfaces, and the bottom surface is an arc. In addition, the flake tooth meshes with the output gear to transmit motion and power, just like the inner and outer gear rings meshing with each other, which greatly increases the contact points or lines. When multiple flake teeth and the output gear mesh and drive, the combined stress on the output gear and the flake tooth will be greatly reduced; The flake tooth assembly and the flake tooth are in a threaded fit. The lower end of the flake tooth assembly is spherical and is matched with the groove of the cylindrical cam. The cylindrical cam rotates to drive the flake tooth assembly to move along the groove, realizing the axial movement of the flake tooth and the flake tooth assembly; The deep groove ball bearing has a hole-basis fit with the output gear, has a shaft-basis fit with the upper end of the cylindrical cam, and restricts the axial movement of the bearing through the cylindrical cam and the output gear, and fixes the two ends of the deep groove ball bearing unidirectionally; The lower end of the output gear has a hole-basis fit with the deep groove ball bearing, and the upper end has a hole-basis fit with the output end ball bearing. The output gear transmits motion and power through the flake tooth and outputs outward through the upper flange.

2. The precision reducer based on cam-gear combined drive according to claim 1, characterized in that, the output end ball bearing is an angular contact ball bearing, has a shaft-basis fit with the upper end cover, has a hole-basis fit with the output gear, and restricts the axial movement of the bearing through the output gear and the upper end cover, and fixes the two ends of the output end ball bearing unidirectionally.

3. The precision reducer based on cam-gear combined drive according to claim 1, characterized in that, The input shaft drives the cylindrical cam and the planar groove cam to rotate together. The lower end of the swing rod moves in a push stroke - return stroke along the groove of the planar groove cam, and the upper end makes a reciprocating swing, driving the flake teeth to make a reciprocating motion. At the same time, the flake teeth move axially along the groove of the cylindrical cam, periodically engaging and disengaging the output gear, and the output gear transmits motion and power through the flake teeth.

4. A precision reducer based on cam - gear combined drive according to claim 1, characterized in that when the cylindrical cam and the planar groove cam rotate together, the lower end of a swing rod makes a push stroke motion, and the upper end drives the flake teeth to rotate around the central axis of the output gear through meshing transmission, and the flake teeth transmit motion and power to the output gear; before the lower end of the swing rod makes a return stroke motion, the flake tooth assembly moves axially along the groove of the cylindrical cam, driving the flake teeth to disengage from the output gear, and at this time the motion of the output gear is transmitted through other flake teeth; when the lower end of the swing rod makes a return stroke motion, the upper end of the swing rod drives the flake teeth to make a rotation opposite to the motion of the output gear around the central axis of the output gear, and at this time the motion of the output gear is still transmitted through other flake teeth; when the planar groove cam rotates one week and the lower end of the swing rod is about to start making a push stroke motion again, the flake tooth assembly moves axially along the groove of the cylindrical cam, driving the flake teeth to engage with the output gear. During the whole motion process, the output gear only rotates one tooth. In this way, the cycle repeats. Whenever the planar groove cam and the cylindrical cam rotate one week, the output gear only rotates one tooth, thereby achieving a large reduction ratio transmission.

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