A precision speed reducer

Abstract

The present invention discloses a precision reducer, comprising a base, an input end ball bearing, a plane groove cam, a cylindrical cam, a rocker, a plate tooth, a deep groove ball bearing, an output gear, an output flange, an output end ball bearing, and an upper end cover. The precision reducer is a two-stage reduction type. The first stage of reduction occurs between the plane groove cam and the rocker, and the second stage of reduction occurs between the rocker and the plate tooth. The present invention breaks the multiple gear meshing transmission adopted by the traditional reducer, and cleverly combines the cam and the gear together; in addition, it improves the traditional reducer, which causes the gear teeth of each gear to be subjected to a large synthetic stress due to the small contact area of ​​the gear teeth. Compared with the traditional gear system, the gear has a longer working life. Compared with the currently commonly used industrial robot joint precision reducer, it has a simple and compact structure and a small size, while being able to transmit a larger torque and realize a transmission with a large reduction ratio, which can meet the needs of the industrial robot joint for a high-precision reducer.

Description

Technical Field

[0001] The present invention relates to the technical field of speed reducers, and particularly to a novel precision speed reducer. 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 surface, 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 transmission 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 transmission that relies on a wave generator to cause controllable elastic deformation of a flexible gear 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] Aiming at the meshing transmission of multiple gears used in the transmission system of traditional speed reducers, based on the cam transmission principle and the gear meshing transmission principle, combined with an innovative internal transmission structure, the present invention proposes an innovative principle of cam-gear combined transmission, and greatly improves the situation of very small contact area between gears in a traditional gear train, increasing 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. 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, comprising a base, an input end ball bearing, a planar groove cam, a cylindrical cam, a swing rod, a piece of teeth, a deep groove ball bearing, an output gear, an output flange, an output end ball bearing, and an upper end cover. The precision reducer is of a two-stage reduction type. 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 of teeth.

[0008] The input end ball bearing mentioned above is an angular contact ball bearing, which is in a hole-basis fit with the planar groove cam and a shaft-basis fit with the base. The axial movement of the input end ball bearing is restricted by the base and the planar groove cam, and the two ends of the input end bearing are fixed unidirectionally.

[0009] The planar groove cam mentioned above transmits motion and power through the input shaft. The groove of the cam is divided into two sections. The planar groove cam rotates around the central axis to make the swing rod perform a push stroke - return stroke motion.

[0010] The cylindrical cam and the planar groove cam are connected together by bolts and move together. The cylindrical cam rotates around the central axis to control the axial movement of the piece of teeth.

[0011] The swing rod mentioned above is fixed on the upper end cover. The bottom of the lower end of the swing rod is spherical and is matched with the groove of the planar groove cam. It makes a push stroke - return stroke motion as the planar groove cam rotates. The top surface of the upper end is an arc surface, and the two side surfaces are vertical planes, which mesh with the piece of teeth to drive the piece of teeth to make a reciprocating swing.

[0012] The two side surfaces of the notch of the piece of teeth that cooperate with the swing rod are arc surfaces, and the bottom surface is a conjugate surface. The lower end of the piece of teeth is spherical and is matched with the groove of the cylindrical cam. When the cylindrical cam rotates around the central axis, the piece of teeth moves up and down along the axis. In addition, the piece of teeth 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 pieces of teeth and the output gear mesh and drive, the combined stress on the output gear and the piece of teeth will be greatly reduced.

[0013] The deep groove ball bearing mentioned above is in a shaft-basis fit with the output gear. The axial movement of the bearing is restricted by the cylindrical cam and the output gear, and the two ends of the deep groove ball bearing are fixed unidirectionally.

[0014] The output gear and the output flange are in an interference fit. The output gear is driven by the piece of teeth to drive the flange to rotate and transmit motion and power to the outside.

[0015] The output end ball bearing mentioned above is an angular contact ball bearing, which is in a hole-basis fit with the output flange and a shaft-basis fit with the upper end cover. The axial movement of the output end ball bearing is restricted by the output flange and the upper end cover, and the two ends of the output end bearing are fixed unidirectionally.

[0016] The kinematic relationships of the important components of the present invention are as follows: When the input shaft drives the planar groove cam and the cylindrical cam to rotate together, the lower end of the swing rod moves in a push - return motion along the groove of the planar groove cam, and the upper end makes a reciprocating swing, thereby driving the toothed plate to make a reciprocating motion. At the same time, the lower end of the toothed plate moves up and down along the groove of the cylindrical cam in the axial direction, periodically engaging and disengaging the output gear.

[0017] The working principle of the present invention is as follows: When the planar groove cam and the cylindrical cam rotate together, the lower end of a swing rod moves in a push motion along the groove of the groove cam. At this time, the upper end of the swing rod drives the toothed plate to rotate around the central axis of the output gear through meshing transmission, so that the toothed plate transmits motion and power to the output gear, making the output gear perform a one - way rotary motion; during the process of the lower end of the swing rod making a return motion, the toothed plate moves axially along the groove of the cylindrical cam and separates from the output gear. At the same time, the upper end of the swing rod drives the toothed plate to rotate around the central axis of the output gear in the opposite direction to the motion of the output gear. At this time, the motion of the output gear is transmitted through other toothed plates; whenever the planar groove cam rotates one week and the lower end of the swing rod is about to start a push motion again, the toothed plate moves axially along the groove of the cylindrical cam and engages with the output gear. During the entire 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.

[0018] Due to the adoption of the above - mentioned technical solution, the present invention has the following beneficial effects:

[0019] 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.

[0020] 2. A new type of precision reducer greatly improves the problem that the combined stress on the teeth of each gear is relatively large due to the small contact area of the teeth in traditional reducers. Compared with traditional gear systems, the working life of the gears is longer.

[0021] 3. A new type of precision reducer, compared with the precision reducers commonly used in industrial robot joints 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

[0022] Figure 1 It is a structural diagram of a precision reducer.

[0023] Figure 2 It is a part drawing of a planar groove cam.

[0024] Figure 3 It is a part drawing of a cylindrical cam.

[0025] Figure 4 It is a part drawing of the swing rod.

[0026] Figure 5 It is a part drawing of the chip tooth.

[0027] The markings in the figure: 1 bolt, 2 base, 3 input end ball bearing, 4 planar groove cam, 5 cylindrical cam, 6 screw, 7 chip tooth, 8 swing rod, 9 deep groove ball bearing, 10 output gear, 11 output flange, 12 output end ball bearing, 13 upper end cover, 14 screw. Specific implementation manners

[0028] Referring to the attached drawings, a precision reducer includes: base 2, input end ball bearing 3, planar groove cam 4, cylindrical cam 5, swing rod 8, chip tooth 7, deep groove ball bearing 9, output gear 10, output flange 11, output end ball bearing 12, and upper end cover 13. The novel precision reducer is a two-stage reduction type. The first-stage reduction occurs between the planar groove cam 4 and the swing rod 8, and the second-stage reduction occurs between the swing rod 8 and the chip tooth 7.

[0029] 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, which is in hole-basis fit with the planar groove cam 4, in shaft-basis fit with the base 2, and the axial movement of the input end ball bearing 3 is restricted by the base 2 and the planar groove cam 4, with one-way fixing at both ends of the input end ball bearing 3. The planar groove cam 4 transmits motion and power through the input shaft. The groove of the planar groove cam 4 is divided into two sections. The planar groove cam 4 rotates around the central axis to make the swing rod 8 perform a forward stroke - return stroke motion. The cylindrical cam 5 and the planar groove cam 4 are connected together by screws 6 and move together. The cylindrical cam 5 rotates around the central axis to control the axial movement of the fluted teeth 7. The swing rod 8 is fixed on the upper end cover 12. The bottom of the lower end of the swing rod 8 is spherical and mates with the groove of the planar groove cam 4, and performs a forward stroke - return stroke motion as the planar groove cam 4 rotates. The top surface of the upper end of the swing rod 8 is an arc surface, and the two side surfaces are vertical planes, which mesh and drive with the fluted teeth, mesh and drive with the fluted teeth 7, and drive the fluted teeth 7 to perform a reciprocating motion. The two side surfaces of the notch of the fluted teeth 7 that mates with the swing rod 8 are arc surfaces, and the bottom surface is a conjugate surface. The lower end of the fluted teeth 7 is spherical and mates with the groove of the cylindrical cam 5. When the cylindrical cam 5 rotates around the central axis, the fluted teeth 7 move up and down along the axis. In addition, the fluted teeth 7 mesh with the output gear 10 to transmit motion and power, just like the inner and outer gear rings meshing with each other, greatly increasing the contact points or lines. When multiple fluted teeth 7 and the output gear 10 mesh and drive, the combined stress on the output gear 10 and the fluted teeth 7 will be greatly reduced. The deep groove ball bearing 9 is in shaft-basis fit with the output gear 10, and the axial movement of the deep groove ball bearing 9 is restricted by the cylindrical cam 5 and the output gear 10, with one-way fixing at both ends of the deep groove ball bearing 9. The output gear 10 and the output flange 11 are in interference fit. The output gear 10 is driven by the fluted teeth 7, thereby driving the output flange 11 to rotate and transmitting motion and power to the outside. The output end ball bearing 12 is an angular contact ball bearing, which is in hole-basis fit with the output flange 11, in shaft-basis fit with the upper end cover 13, and the axial movement of the output end ball bearing 12 is restricted by the output flange 11 and the upper end cover 13, with one-way fixing at both ends of the output end bearing 12.

[0030] The motion relationship of the important components of the present invention is as follows: The input shaft drives the planar groove cam 4 and the cylindrical cam 5 to rotate together. The lower end of the swing rod 8 moves along the groove of the planar groove cam 4 to perform a forward stroke - return stroke motion, and the upper end performs a reciprocating swing, thereby driving the fluted teeth 7 to perform a reciprocating motion. At the same time, the fluted teeth 7 move axially along the groove of the cylindrical cam 5, periodically engaging and disengaging the output gear 10.

[0031] The working principle of the present invention is as follows: When the planar groove cam 4 and the cylindrical cam 5 rotate together, the lower end of a swing rod 8 performs a forward stroke movement. The upper end of the swing rod 8 drives the fluted gear 7 to rotate around the central axis of the output gear 10 through meshing transmission. The fluted gear 7 transmits motion and power to the output gear 10. During the process when the lower end of the swing rod 8 performs a return stroke movement, the fluted gear 7 moves axially along the groove of the cylindrical cam 5 and separates from the output gear 10. At the same time, the upper end of the swing rod 8 drives the fluted gear 7 to rotate around the central axis of the output gear 10 in a direction opposite to the movement of the output gear 10. At this time, the movement of the output gear 10 is still transmitted through other fluted gears 7. Every time the planar groove cam 4 rotates one week, after the lower end of the swing rod 8 starts to perform a forward stroke movement again, the fluted gear 7 moves axially along the groove of the cylindrical cam 5 and engages with the output gear 10. During the entire movement process, the output gear 10 only rotates one tooth. In this way, the cycle repeats. Every time the planar groove cam 4 and the cylindrical cam 5 rotate one week, the output gear 10 only rotates one tooth, thereby achieving a large reduction ratio transmission.

Claims

1. A precision speed reducer, characterized in that, It includes a base, an input end ball bearing, a planar groove cam, a cylindrical cam, a swing rod, a piece of teeth, a deep groove ball bearing, an output gear, an output flange, an output end ball bearing, and an upper end cover; the precision reducer is of two-stage reduction type; 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 of teeth; The input end ball bearing is an angular contact ball bearing, which is in hole-basis fit with the planar groove cam and in shaft-basis fit with the base. The axial movement of the input end ball bearing is restricted by the base and the planar groove cam, and the two ends of the input end ball bearing are fixed unidirectionally; The planar groove cam transmits motion and power through the input shaft. The groove of the cam is divided into two sections. The planar groove cam rotates around the central axis to make the swing rod perform a forward stroke - return stroke motion; The cylindrical cam and the planar groove cam are connected together by bolts and move together. The cylindrical cam rotates around the central axis to control the axial movement of the piece of teeth; The swing rod is fixed on the upper end cover. The bottom of the lower end of the swing rod is spherical and is matched with the groove of the planar groove cam, and performs a forward stroke - return stroke motion as the planar groove cam rotates; The two side surfaces of the notch where the piece of teeth is matched with the swing rod are arc surfaces, and the bottom surface is a conjugate surface. The lower end of the piece of teeth is spherical and is matched with the groove of the cylindrical cam. When the cylindrical cam rotates around the central axis, the piece of teeth moves up and down along the axis direction. The piece of teeth meshes with the output gear to transmit motion and power, and the inner and outer gear rings mesh with each other to increase the contact points or lines. When multiple pieces of teeth and the output gear mesh and drive, the combined stress on the output gear and the piece of teeth will decrease; The output gear and the output flange are in interference fit. The output gear is driven by the piece of teeth, so as to drive the flange to rotate and transmit motion and power to the outside.

2. The precision reducer according to claim 1, wherein The deep groove ball bearing is in shaft-basis fit with the output gear. The axial movement of the bearing is restricted by the cylindrical cam and the output gear, and the two ends of the deep groove ball bearing are fixed unidirectionally.

3. A precision speed reducer according to claim 1, characterized in that, The output end ball bearing is an angular contact ball bearing, which is in hole-basis fit with the output flange and in shaft-basis fit with the upper end cover. The axial movement of the output end ball bearing is restricted by the output flange and the upper end cover, and the two ends of the output end bearing are fixed unidirectionally.

4. A precision speed reducer according to claim 1, characterized in that, When the input shaft drives the planar groove cam and the cylindrical cam to rotate together, the lower end of the swing rod moves along the groove of the planar groove cam to perform a forward stroke - return stroke motion, and the upper end performs a reciprocating swing, thereby driving the piece of teeth to perform a reciprocating motion; at the same time, along with the up and down movement of the lower end of the piece of teeth along the groove of the cylindrical cam in the axial direction, the output gear is periodically engaged and disengaged.

5. A precision speed reducer according to claim 1, characterized in that, When the planar groove cam and the cylindrical cam rotate together, the lower end of a swing rod moves in a pushing stroke along the groove of the groove cam. At this time, the upper end of the swing rod drives the fluted teeth to rotate around the central axis of the output gear through meshing transmission, so that the fluted teeth transmit motion and power to the output gear, causing the output gear to perform a one-way rotary motion; during the process of the lower end of the swing rod moving in a return stroke, the fluted teeth move axially along the groove of the cylindrical cam and separate from the output gear. At the same time, the upper end of the swing rod drives the fluted teeth to rotate around the central axis of the output gear in the direction opposite to the motion of the output gear, and the motion of the output gear is transmitted through other fluted teeth; whenever the planar groove cam rotates one week and the lower end of the swing rod is about to start a pushing stroke again, the fluted teeth move axially along the groove of the cylindrical cam and 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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