CN115560063A - Planetary transmission mechanism without side clearance - Google Patents

Abstract

The invention belongs to the field of mechanical design, and relates to a backlash-free planetary transmission mechanism which comprises a sun gear, an inner gear ring and a plurality of planetary gears, wherein the plurality of planetary gears are arranged in the inner gear ring and around the sun gear, and the sun gear, the planetary gears and the inner gear ring are matched by adopting special gears with variable tooth thicknesses; the variable tooth thickness direction and size of the sun gear and the inner gear ring are the same, the variable tooth thickness direction of the planet gear is opposite to that of the sun gear and the inner gear ring, and the variable tooth thickness size is the same. The invention adjusts the parameters of the tooth direction, addendum circle and the like of each inner gear and each outer gear, thereby achieving the purpose that the tooth thickness is uniformly increased or reduced at different axial sections, and then forcing two gears engaged by the gear pair to generate axial displacement through the external accurate application of the axial force on the end surface of the planet wheel, thereby completing the backlash-free engagement between the gear pairs. Meanwhile, because the axial force applied externally is controllable, the automatic centering device can not generate adverse effects such as meshing interference and the like, and can also ensure the automatic centering function in movement.

Description

Backlash-free planetary transmission mechanism

Technical Field

The invention belongs to the field of mechanical design and relates to a backlash-free planetary transmission mechanism.

Background

In order to ensure good operation, installation and processing performance of the existing planetary transmission mechanism, the paired gear pairs are designed to be in clearance fit, the intervention of backlash directly causes idle stroke of the gear pairs in the operation process, the requirement on the transmission motion of the planetary gear pair with general precision is not high, and therefore the influence on the motion precision of a final product is hardly considered in the clearance of the gear pair of the conventional planetary transmission mechanism. However, in the situation of requiring a particularly high precision of the transmission motion, the backlash of the gear pair directly results in the precision and the stability of the transmission motion, and in order to reduce the backlash between the gear pair, the precision of each gear is continuously increased, which not only increases the difficulty and the cost of production and assembly, but also only reduces or cannot completely eliminate the meshing backlash of the gear pair.

Disclosure of Invention

In view of this, the present invention provides a backlash-free planetary transmission mechanism, which ensures no backlash in the meshing process of a gear pair by a special structure on the premise of maintaining a certain precision, thereby achieving high-precision planetary transmission.

In order to achieve the purpose, the invention provides the following technical scheme: a planetary transmission mechanism without backlash comprises a sun gear, an inner gear ring and a plurality of planet gears, wherein the planet gears are arranged in the inner gear ring and arranged around the sun gear; the variable tooth thickness direction and size of the sun gear and the inner gear ring are the same, the variable tooth thickness direction of the planet gear is opposite to that of the sun gear and the inner gear ring, and the variable tooth thickness size is the same.

Optionally, the planet gear is arranged on the planet carrier.

Optionally, a planet carrier cushion block for axial positioning is arranged on the planet carrier, and the planet carrier cushion block is clamped on the planet carrier through a hole by an elastic retainer ring and is positioned by the upper end face of the lower-stage sun gear.

Optionally, the planet wheel is installed on the planet carrier through a pin shaft, the pin shaft is in interference fit with the planet carrier through t6/H6, an elastic check ring for the shaft is arranged, and the planet carrier pin shaft is prevented from being axially pulled out.

Optionally, the planet wheel passes through thrust ball bearing and dish spring setting on the planet frame, uses the dish spring to add the axial force in advance on the planet frame, and the rethread thrust ball bearing transmits the axial force to the planet wheel.

Optionally, a pure needle bearing is adopted in the portion, higher than the thrust ball bearing, of the interior of the planet wheel.

Optionally, the variable tooth thickness of the planet gear is big end down, the sun gear and the inner gear ring are big end down, the variable tooth thickness parameters are equal, and the specific numerical value is a conventional backlash value j capable of ensuring the machining precision.

The invention has the beneficial effects that: the invention relates to a backlash-free planetary transmission mechanism, which can achieve the uniform increase or decrease of tooth thickness in different axial sections by adjusting the parameters of the tooth directions, addendum circles and the like of inner and outer gears, and force two gears engaged by a gear pair to generate axial displacement by externally and accurately applying axial force on the end surface of a planet wheel so as to complete the backlash-free engagement between the gear pair. Meanwhile, because the axial force applied externally is controllable, the automatic centering device can not generate adverse effects such as meshing interference and the like, and can also ensure the automatic centering function in movement.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims thereof.

Drawings

For the purposes of promoting a better understanding of the objects, aspects and advantages of the invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic view of the overall structure of the present invention;

FIG. 2 is a schematic view of the tooth thickness adjustment of the present invention;

fig. 3 is a view from direction K of fig. 2.

Reference numerals are as follows: the device comprises a sun wheel 1, a planet carrier 2, a planet wheel 3, an inner gear ring 4, a pure needle bearing 5, a thrust ball bearing 6, a disc spring 7, an elastic retainer ring for a shaft 8, a pin shaft 9, a planet carrier cushion block 10 and an elastic retainer ring for a hole 11.

Detailed Description

The following embodiments of the present invention are provided by way of specific examples, and other advantages and effects of the present invention will be readily apparent to those skilled in the art from the disclosure herein. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention in a schematic way, and the features in the following embodiments and examples may be combined with each other without conflict.

Wherein the showings are for the purpose of illustration only and not for the purpose of limiting the invention, shown in the drawings are schematic representations and not in the form of actual drawings; for a better explanation of the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there is an orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "front", "rear", etc., based on the orientation or positional relationship shown in the drawings, it is only for convenience of description and simplification of description, but it is not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore the terms describing the positional relationship in the drawings are only used for illustrative purposes and are not to be construed as limiting the present invention, and the specific meaning of the terms described above will be understood by those skilled in the art according to the specific circumstances.

Referring to fig. 1 to 3, a backlash-free planetary transmission mechanism includes a sun gear 1, an inner gear ring 4 and a plurality of planet gears 3, wherein the plurality of planet gears 3 are disposed in the inner gear ring 4 and around the sun gear 1, the planet gears 3 and the inner gear ring 4 are all matched by using special gears with variable tooth thickness, the sun gear 1 rotates to drive the planet gears 3 engaged therewith to rotate, so as to drive the inner gear ring 4 engaged with the planet gears 3 to rotate; the variable tooth thickness direction and the size of the sun gear 1 and the inner gear ring 4 are the same, the variable tooth thickness direction of the planet gear 3 is opposite to that of the sun gear 1 and the inner gear ring 4, the variable tooth thickness size is the same, the planet gear 3 is arranged on the planet carrier 2, a planet carrier cushion block 10 for axial positioning is arranged on the planet carrier 2, and the planet carrier cushion block 10 is clamped on the planet carrier 2 through a hole by an elastic retainer ring 11 and is positioned by the upper end face of the lower sun gear 1.

In this embodiment, in order to prevent the occurrence of the axial pin pulling phenomenon of the pin shaft 9 of the planet carrier 2, the planet wheel 3 is installed on the planet carrier 2 through the pin shaft 9, the pin shaft 9 and the planet carrier 2 are in interference fit with each other by t6/H6, and the shaft elastic collar 8 is adopted for secondary protection.

In this embodiment, planet wheel 3 passes through thrust ball bearing 6 and dish spring 7 sets up on planet carrier 2, uses dish spring 7 to add the axial force in advance on planet carrier 2, and rethread thrust ball bearing 6 transmits the axial force to planet wheel 3, uses thrust ball bearing 6 can reduce resistance and power loss that relative slip produced in service by a wide margin.

In this embodiment, in order to adapt to the axial displacement condition of the planet wheel 3, the pure needle bearing 5 is adopted in the part higher than the thrust ball bearing 6 inside the planet wheel 3, so that the matching and operation effect of the bearing and the planet wheel 3 can be well guaranteed after the planet wheel 3 moves up and down.

In the embodiment, the planet gear 3 has the variable tooth thickness with the small upper part and the large lower part, the sun gear 1 and the inner gear ring 4 have the large upper part and the small lower part, the variable tooth thickness parameters are equal, the specific numerical value is a conventional backlash value j which can ensure the processing precision, and the left tooth surface and the right tooth surface are respectively half of each other, so the stressed meshing of the whole gear is in line contact and is the same as the meshing contact in the conventional design. And after the assembly is finished, the backlash of the planetary mechanism is completely eliminated, and the planetary mechanism is in a backlash-free state, so that the transmission precision is not lost. Because each planet wheel 3 is provided with a disc spring 7 for applying axial force, the requirement on the tooth thickness difference of the planet wheels 3 is not high. In order to ensure that the planetary transmission mechanism has flexible operation, no clamping stagnation, small starting torque and high efficiency, the axial force on the planetary wheel 3 needs to be calculated, and the axial force F = F0 (circumferential force) x sin alpha (tooth surface axial included angle) is caused by changing the tooth thickness into the taper. And selecting the disc spring 7 corresponding to the axial force according to the calculated axial force to counteract the meshing axial force. F0 The maximum dynamic load (circumferential force) or the frequency of use is selected to ensure that the gears are engaged in backlash-free motion for at least 90% of the service life.

In the present embodiment, the variable tooth thickness of the sun gear 1 and the planetary gears 3 is changed by tooth grinding. The reference value of the designed standard tooth thickness is the small end of the gear tooth thickness, namely the lower end of the sun gear 1 and the upper end of the planet gear 3. For reducing the meshing interference of the gear tooth tops while changing the tooth thickness, the tooth top circle of each gear needs to be designed in a taper manner, the taper direction is the same as the tooth direction taper direction, and the size of the taper direction is 1 time of the tooth thickness changing value of the tooth direction tooth thickness. Meanwhile, in order to ensure enough meshing tooth width, the tooth width of the sun gear 1 and the inner gear ring 4 needs to be 15-20% larger than that of the planet gear 3 in design. For the taper and variable tooth thickness processing of the inner gear ring 4, the main shaft of the gear shaper can be deflected by an angle which is the same as the included angle alpha between the variable tooth thickness of the inner gear and the axis.

The invention solves the precision of the transmission motion of the conventional planetary transmission mechanism, and changes the conventional necessary clearance design into the non-backlash meshing motion by the special adjusting mechanism, thereby ensuring the precision of the transmission motion of the planetary transmission mechanism.

Finally, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (7)

1. The utility model provides a no backlash planetary drive mechanism which characterized in that: the sun gear, the planet gears and the inner gear ring are matched by adopting special gears with variable tooth thicknesses, and the sun gear rotates to drive the planet gears meshed with the sun gear to rotate so as to drive the inner gear ring meshed with the planet gears to rotate;

the variable tooth thickness direction and size of the sun gear and the inner gear ring are the same, the variable tooth thickness direction of the planet gear is opposite to that of the sun gear and the inner gear ring, and the variable tooth thickness size is the same.

2. The backlash-free planetary gear set as in claim 1, wherein: the planet wheel is arranged on the planet carrier.

3. A backlash-free planetary gear mechanism as claimed in claim 2, wherein: the planet carrier is provided with a planet carrier cushion block for axial positioning, the planet carrier cushion block is clamped on the planet carrier through a hole by an elastic retainer ring and is positioned by the upper end surface of the lower-level sun gear.

4. A backlash-free planetary gear mechanism as claimed in claim 2, wherein: the planet wheel is installed on the planet carrier through the round pin axle, and the interference fit of t 6H 6 is adopted in the cooperation of round pin axle and planet carrier to be provided with the circlip for the axle, prevent that planet carrier round pin axle axial pull out the round pin phenomenon and take place.

5. A backlash-free planetary gear mechanism as claimed in claim 2, wherein: the planet wheel passes through thrust ball bearing and dish spring setting on the planet frame, uses the dish spring to add the axial force in advance on the planet frame, and the rethread thrust ball bearing transmits the axial force to the planet wheel.

6. The backlash-free planetary gear set as in claim 4, wherein: the part of the interior of the planet wheel, which is higher than the thrust ball bearing, adopts a pure needle bearing.

7. The backlash-free planetary gear set as in claim 1, wherein: the variable tooth thickness of the planet wheel is big end down, the sun wheel and the inner gear ring are big end down, the variable tooth thickness parameters are equal, and the specific numerical value is a conventional backlash value j capable of ensuring the machining precision.

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