A planetary gear reducer with same-side input and output and hollow structure

Abstract

The present invention discloses a planetary gear reducer with a hollow structure and capable of same-side input and output. The invention solves the problem that when existing planetary gear reducers are applied to robots, the cables of the robots cannot be built in, resulting in a large device size and the inability to meet the use requirements in some areas with limited space. The reducer installs the input gear in the planetary frame of the Nth-stage planetary gear reduction mechanism, and uses the central shaft sleeve to pass through the central through holes of each stage of the sun gear in sequence. One end of the reducer is fixedly connected to the input gear, and the other end is fixedly connected to the first-stage sun gear through a baffle cover. The interior of the central sleeve serves as a wire passing hole, which not only enables the reducer to realize power input and output on the same side, but also takes into account the purpose of the cables being able to directly pass through the reducer, thereby making the planetary gear reducer more suitable for use on specific axes of some robots.

Description

Technical Field

[0001] The invention relates to a gear transmission device, in particular to a planetary gear reducer with same-side input and output and a hollow structure. Background Art

[0002] In recent years, the number of auxiliary equipment connected to industrial machinery has increased. As a result, the number of cables that need to pass through the reducer has increased. Therefore, it is becoming increasingly important to design a reducer with a large hollow structure. Especially for robots, the need to achieve compactness and cable-free teaching has become particularly important.

[0003] Existing robot reducers usually adopt RV reducer structure. The advantages of RV reducer are small size and large reduction ratio. For example, Chinese patent, publication number: CN106641110A discloses a "high rigidity hollow RV reducer for industrial robots". The advantages of RV reducer are small size and large reduction ratio, but relatively speaking, due to the use of cycloid gear structure, it is difficult to process, high cost, low transmission efficiency, and poor precision retention. Planetary gear reducer is superior to RV reducer in terms of cost, efficiency, precision retention, etc.

[0004] However, there are currently no planetary gear reducers with hollow structures on the market. Existing planetary gear reducers, such as CN200710068194.9 and CN103322138A, cannot meet the requirements of built-in cables for robots. The cable layout is relatively random, which makes the entire device larger. In addition, since the power input and output of existing planetary gear reducers are located on both sides when applied to robots, when high-precision transmission and compact robots are required in some space-constrained areas, the existing planetary gear reducers cannot meet the use requirements.

[0005] In addition, the existing planetary gear reducer has the following problems:

[0006] 1. A large number of retaining springs are used for axial positioning, which not only occupies the axial size, but also increases the span of the planetary shaft itself and weakens the rigidity. At the same time, due to the large axial size, it will not be able to meet some scenarios with more stringent requirements on the use space.

[0007] 2. The planetary gear reducer uses deep groove ball bearings between the low-speed planet carrier and the inner gear housing as the output end. However, since deep groove ball bearings are mainly used to bear radial loads, their bearing capacity for axial loads is weak, which reduces the reducer's bearing capacity for axial and moment loads. In some structures, deep groove ball bearings are replaced with double-row angular contact ball bearings, but the use of such bearings will make the entire reducer occupy too much space and also reduce the power density of the reducer. Summary of the invention

[0008] In order to solve the problem that when existing planetary gear reducers are applied to robots, the cables of the robots cannot be built-in, resulting in a large device size, and because the power input and output of existing planetary gear reducers are located on both sides respectively when applied to robots, when high-precision transmission and compact robots are required in some space-constrained areas, the existing planetary gear reducers cannot meet the use requirements, the present invention provides a planetary gear reducer with same-side input and output and a hollow structure.

[0009] The specific technical solution of the present invention is:

[0010] A planetary gear reducer with same-side input and output and a hollow structure, comprising an inner gear housing and N-stage planetary gear reduction mechanisms arranged in sequence along the axial direction of the inner gear housing; N≥2; each stage of the planetary gear reduction mechanism comprises a sun gear, a planetary gear, a planet carrier and a planetary shaft;

[0011] The improvements are:

[0012] It also includes input gear, center sleeve, baffle cover and steel ring;

[0013] The sun gears of each level of planetary gear reduction mechanism have a central through hole, and the center of the planet carrier of the Nth level planetary gear reduction mechanism is provided with a multi-step through hole;

[0014] The central sleeve is coaxially installed in the central through hole of each level of sun gear and the through hole of the multi-level step, and the central sleeve is respectively kept in clearance fit with the central through hole of each level of sun gear; one end of the central sleeve is coaxially fixedly connected with the input gear located in the large diameter hole in the through hole of the multi-level step, and the other end of the central sleeve is pressed and fitted with the blocking cover, and the blocking cover is fixedly connected with the sun gear of the first-stage planetary gear reduction mechanism;

[0015] A bearing for supporting and positioning is installed on the outer surface of the central sleeve and at the position of the middle diameter hole corresponding to the multi-step through hole, and the interior of the central sleeve is a wire passage for the cable to pass through;

[0016] A retaining ring is fixedly arranged on the sun gear in the first-stage planetary gear reduction mechanism, and the end face of the retaining ring contacts the end face of the planetary gear in the first-stage planetary gear reduction mechanism, and is used for axial positioning of the planetary gear in the first-stage planetary gear reduction mechanism.

[0017] Furthermore, the above-mentioned baffle cover includes a circular portion and a conical cylinder portion arranged on the circular portion; the central through hole of the sun gear in the first-stage planetary gear reduction mechanism has a conical hole section; the conical cylinder portion forms a conical surface match with the conical hole section; the screw passes through the circular portion and is threadedly connected to the sun gear of the first-stage planetary gear reduction mechanism.

[0018] Furthermore, in the above-mentioned 2nd to Nth stage planetary gear reduction mechanisms, the sun gear is provided with a first external tooth and a second external tooth, and the tooth height of the first external tooth is greater than the tooth height of the second external tooth; the first external tooth is meshed with the planetary gear of the current stage, and the second external tooth is key-connected with the planetary carrier of the previous stage; the end face of the planetary carrier of the previous stage contacts the end face of the first external tooth on the sun gear of the current stage, and at the same time forms a micro gap with the end face of the planetary gear of the current stage;

[0019] The planet shaft of each stage of the planetary gear reduction mechanism is interference fit with the planet shaft mounting hole on the planet carrier, and the planet wheel and the planet carrier of the Nth stage planetary gear reduction mechanism contact each other to realize the axial positioning of the planet wheel in the Nth stage planetary gear reduction mechanism.

[0020] Furthermore, the planet carrier of the Nth-stage planetary gear reduction mechanism and the inner gear housing are rotationally connected via at least one row of contact ball bearing structures, and the contact ball bearing structure realizes the axial positioning of the planet carrier in the Nth-stage planetary gear reduction mechanism;

[0021] The contact ball bearing structure includes M first inner ring outer raceways arranged along the axial direction on the outer surface of the planet carrier of the N-th stage planetary gear reduction mechanism, and M first outer ring inner raceways corresponding to the M first inner ring outer raceways are arranged on the inner wall of the inner gear housing along the axial direction; M≥1;

[0022] M steel ball installation raceways are formed between the M first inner ring outer raceways and the M first outer ring inner raceways; a plurality of first steel balls are arranged in each steel ball installation raceway along the circumferential direction;

[0023] At least one axial hole is arranged on the planet carrier of the Nth stage planetary gear reduction mechanism, and M ball loading holes are arranged at positions corresponding to the axial hole and the outer raceway of the second inner ring, and each ball loading hole is provided with an anti-escape structure to prevent the ball from escaping.

[0024] Furthermore, a limiting hole is also provided on the planet carrier of the above-mentioned Nth-stage planetary gear reduction mechanism, and the limiting hole is connected to the ball loading hole; a limiting device is provided in the limiting hole to prevent the anti-escape structure from moving.

[0025] Furthermore, the above-mentioned limiting hole is a screw hole parallel to the axial hole, and the limiting device is a tightening screw.

[0026] Furthermore, when the above M is 1: the steel ball mounting raceway includes four eccentric arcs, each of which occupies 1 / 4 of the circumference of the cross-section, and the second steel ball is in point contact with the four arcs of the steel ball mounting raceway.

[0027] Furthermore, when the above M is 2,

[0028] The first ball installation raceway consists of four eccentric arcs, each of which occupies 1 / 4 of the cross-section circumference;

[0029] The second ball installation raceway consists of four eccentric arcs, each of which occupies 1 / 4 of the circumference of the cross section;

[0030] The arc of the first steel ball mounting raceway is the same as the arc of the second steel ball mounting raceway, and the second steel ball is in point contact with the four arcs of the first steel ball mounting raceway, as well as the second steel ball and the four arcs of the second steel ball mounting raceway.

[0031] Furthermore, when the above M is 2,

[0032] The first ball installation raceway consists of two eccentric arcs, each of which occupies 1 / 2 of the cross-section circumference;

[0033] The second ball installation raceway consists of two eccentric arcs, each of which occupies 1 / 2 of the circumference of the cross section;

[0034] The arc of the first steel ball mounting raceway and the arc of the second steel ball mounting raceway are mirror images.

[0035] Furthermore, when the above M is 3,

[0036] The first ball installation raceway consists of two eccentric arcs, each of which occupies 1 / 2 of the cross-section circumference;

[0037] The second steel ball installation raceway includes four eccentric arcs, each of which occupies 1 / 4 of the circumference of the cross section. The second steel ball is in point contact with the four arcs of the second steel ball installation raceway.

[0038] The third ball installation raceway consists of two eccentric arcs, each of which occupies 1 / 2 of the circumference of the cross section;

[0039] The arc of the first steel ball installation raceway and the arc of the third steel ball installation raceway are mirror images.

[0040] The present invention has the following beneficial effects:

[0041] 1. The reducer of the present invention installs the input gear in the planetary frame of the Nth-stage planetary gear reduction mechanism, and uses the central shaft sleeve to pass through the central through holes of each stage sun gear in sequence. One end of the shaft sleeve is fixedly connected to the input gear, and the other end is fixedly connected to the first-stage sun gear through a cover. The interior of the central sleeve serves as a wire passing hole, which not only enables the reducer to realize power input and output on the same side, but also takes into account the purpose of cables being able to directly pass through the reducer, thereby making the planetary gear reducer more suitable for use with specific axes of some robots (that is, the main use occasion of the reducer with power input and output and with a wire passing hole is the first axis of the robot. Such a same-direction setting enables the motor and the reducer to be installed from the same side from above when the first axis is installed on the robot base, which is convenient for assembly).

[0042] 2. The blocking cover in the present invention is composed of a circular ring portion and a tapered cylinder portion. During assembly, the tapered cylinder portion forms a conical surface match with the sun gear in the first-stage planetary gear reduction mechanism; the screw passes through the circular ring portion and is threadedly connected to the sun gear of the first-stage planetary gear reduction mechanism, thereby not only realizing power transmission and providing a large-diameter hollow space, but also ensuring the coaxiality of the center sleeve and the first-stage planetary gear reduction mechanism.

[0043] 3. The present invention adopts a steel ring to axially position the planetary gear of the first-stage planetary gear reduction mechanism, the current-stage planetary carrier axially positions the planetary gear bearing, and the upper-stage planetary carrier axially positions the first external tooth of the lower-stage sun gear, and at the same time, the planetary gear and the planetary carrier of the same stage are in direct contact to achieve mutual axial positioning; compared with the existing reducer structure, the structure of the present invention not only shortens the overall axial size of the planetary gear reducer, but also reduces the characteristics and quantity of parts, thereby reducing the manufacturing cost.

[0044] 4. In the adjacent two-stage planetary gear reduction mechanism of the present invention, the end face of the upper-stage planet carrier forms a micro gap with the end face of the current-stage planet wheel, which can assume the axial positioning function while leaving space for grease, so that an oil film is established between the contact surfaces, thereby improving lubrication and reducing wear; at the same time, it also increases the manufacturing tolerance and reduces the manufacturing difficulty.

[0045] 5. The planet carrier and the inner gear housing of the Nth-stage planetary gear reduction mechanism of the reducer of the present invention are rotationally connected by arranging at least one row of contact ball bearings. This type of bearing can not only bear radial loads, but also axial loads. Compared with the structure of the existing reducer, the reducer's bearing capacity for axial and bending loads is greatly improved; at the same time, the contact ball bearing structure adopts a filling structure composed of an axial hole, a ball filling hole and an anti-escape structure, thereby avoiding the problem of splicing gaps that are inevitably generated by adopting an upper and lower splicing structure, thereby improving manufacturing accuracy, thereby effectively ensuring the raceway stiffness and reducing the wear of the balls in the raceway caused by the splicing raceway gap. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a schematic diagram of the structure of the planetary gear reducer of the present invention.

[0047] Figure 2 It is a schematic diagram of the structure of a planetary gear reducer with an anti-escape structure.

[0048] Figure 3 for Figure 2 Schematic diagram of the end face of the planet carrier of the third-stage planetary gear reduction mechanism after removing the motor.

[0049] Figure 4 It is a partial schematic diagram of the connection between the baffle cover and the sun gear of the first-stage planetary gear reduction mechanism;

[0050] Figure 5 A partial schematic diagram of the anti-escape structure.

[0051] Figure 6 It is a schematic diagram of a single-row contact ball bearing structure;

[0052] Figure 7 It is a schematic diagram of the first form of the two-row contact ball bearing structure;

[0053] Figure 8 It is a schematic diagram of the second form of the two-row contact ball bearing structure;

[0054] Fig. 9 It is a schematic diagram of the third form of the two-row contact ball bearing structure;

[0055] Fig.10 Schematic diagram of the three-row contact ball bearing structure.

[0056] The reference numerals are as follows:

[0057] 100-inner gear housing, 1001-inner raceway of the first outer ring;

[0058] 200-planetary gear reduction mechanism, 201-sun gear, 2011-first outer tooth, 2012-second outer tooth, 2013-center through hole, 202-planetary gear, 203-planet carrier, 2031-first inner ring outer raceway, 2032-axial hole, 2033-ball filling hole, 2034-multi-step through hole; 204-planetary shaft, 206-planetary shaft mounting hole, 207-planetary gear inner hole;

[0059] 300-center sleeve, 301-wire channel;

[0060] 400-input gear;

[0061] 500-Steel ball installation raceway;

[0062] 600-first steel ball;

[0063] 700-anti-slip structure, 701-pin shaft, 702-limiting hole, 703-tightening screw.

[0064] 800-blocking cover, 801-circular ring portion, 802-conical cylinder portion;

[0065] 900-bearing;

[0066] 1000-Retaining ring. DETAILED DESCRIPTION

[0067] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0068] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0069] At the same time, in the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper, lower, inner and outer" are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first, second or third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0070] In the present invention, unless otherwise clearly specified and limited, the terms "install, connect, connect" should be understood in a broad sense, for example: it can be a fixed connection, a detachable connection or an integral connection; it can also be a mechanical connection, an electrical connection or a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0071] This embodiment provides a planetary gear reducer with a large-diameter hollow structure, such as Figure 1 As shown, the reducer includes an inner gear housing 100 and N-stage planetary gear reduction mechanisms 200 arranged in sequence along the axial direction of the inner gear housing 100; N≥2, in this embodiment, N is 3, wherein the first-stage planetary gear reduction mechanism is the high-speed input end of the reducer, the second-stage planetary gear reduction mechanism is the medium-speed stage, and the third-stage planetary gear reduction mechanism is the low-speed output end of the reducer; each stage of the planetary gear reduction mechanism 200 includes a sun gear 201, a planetary gear 202, a planet carrier 203 and a planet shaft 204.

[0072] In order to meet the requirements of the robot cable being built in, the structural layout of the planetary reducer is made more reasonable, and at the same time, the power input and output are arranged on the same side. In this embodiment, the planetary reducer is designed with the power input and output on the same side and a hollow structure. The specific structure is as follows: Figure 1 and2 As shown: the sun gear 201 of each stage of the planetary gear reduction mechanism has a central through hole 2013, and the center of the planet carrier 203 of the third stage planetary gear reduction mechanism is provided with a multi-step through hole 2034;

[0073] A central sleeve 300 is coaxially installed in the central through hole 2013 of each level of the sun gear 201 and the multi-step through hole 2034, and the central sleeve 300 respectively maintains clearance fit with the central through hole 2013 of each level of the sun gear 201; one end of the central sleeve 300 is coaxially fixedly connected to the input gear 400 located in the large diameter hole in the multi-step through hole 2035, and the other end of the central sleeve 300 forms a press fit with the blocking cover 800, and the blocking cover is connected to the sun gear 201 of the first-stage planetary gear reduction mechanism. 1 is fixedly connected; a bearing 900 for supporting and positioning is installed on the outer surface of the central sleeve 300 and at the position of the middle diameter hole corresponding to the multi-stage step through hole 2034, and the interior of the central sleeve 300 is a wire passage 301 for the cable to pass through; a retaining ring 1000 is fixedly arranged on the sun gear 201 in the first-stage planetary gear reduction mechanism, and the end face of the retaining ring 1000 contacts the end face of the planetary gear 202 in the first-stage planetary gear reduction mechanism, and is used to axially position the planetary gear 202 in the first-stage planetary gear reduction mechanism.

[0074] In this embodiment, Figure 3 As shown, the blocking cover 800 includes a circular portion 801 and a tapered cylinder portion 802 arranged on the circular portion 801; the central through hole 2013 of the sun gear 201 in the first-stage planetary gear reduction mechanism has a tapered hole section; the tapered cylinder portion 802 forms a conical surface match with the tapered hole section; the screw passes through the circular portion and is threadedly connected to the sun gear 201 of the first-stage planetary gear reduction mechanism. The blocking cover 800 cooperates with the tapered surface of the sun gear 201, thereby not only realizing power transmission and providing a large-diameter hollow space, but also ensuring the coaxiality of the center sleeve and the first-stage planetary gear reduction mechanism, thereby ensuring the transmission accuracy of the entire reducer.

[0075] When in use, the external motor transmits power to the central sleeve 300 through the input gear 400, and the central sleeve 300 transmits power to the first-stage planetary gear reduction mechanism through the cover 800, and the first-stage planetary gear reduction mechanism transmits power to the third-stage planetary gear reduction mechanism through the second-stage planetary gear reduction mechanism, and finally the power is transmitted to the subsequent equipment by the planet carrier 203 of the third-stage planetary gear reduction mechanism. And because the interior of the central sleeve 300 has a wire channel 301, the cables of the robot can be built into the wire channel.

[0076] In order to overcome the problem that the existing planetary gear reducer has a large axial dimension, which increases the span of the planetary shaft itself and weakens its rigidity, the planetary gear reducer of this embodiment also adopts an overall axial scaled structural design, which not only overcomes the above problem, but also further meets the use requirements with relatively stringent space requirements. The overall axial scaled structure is specifically as follows: Figure 1 and Figure 2 As shown, the sun gear 201 in the 2nd to 3rd stage planetary gear reduction mechanism 200 is provided with a first external tooth 2011 and a second external tooth 2012 along its own axial direction, and the tooth height of the first external tooth 2011 is greater than the tooth height of the second external tooth 2012; the first external tooth 2011 of each stage of the sun gear 200 is meshed with the planetary gear 202 of the current stage, and the second external tooth 2012 is keyed to the planetary carrier 203 of the previous stage; the end face of the planetary carrier 203 of the previous stage is in contact with the end face of the first external tooth 2011 on the sun gear 201 of the current stage; the planet shaft 204 of each stage of the planetary gear reduction mechanism is interference fit with the planet shaft mounting hole 206 on the planet carrier 203, and the planetary gear 202 and the planet carrier 203 of the 3rd stage planetary gear reduction mechanism are in contact with each other to realize the axial positioning of the planetary gear in the 3rd stage planetary gear reduction mechanism.

[0077] In addition, in order to further reduce the axial size of the reducer, the three-stage planetary gear reduction mechanism in this embodiment shares an internal gear housing 100, and the module of the planetary gear 202 in each stage of the planetary gear reduction mechanism is the same, which can make the width size of the planetary gear 202 in each stage of the planetary mechanism (especially the first stage planetary gear and the second stage planetary gear) thinner.

[0078] In order to solve the problems existing in the use of deep groove ball bearings or double-row angular contact ball bearings between the output end planet carrier and the inner gear housing of the existing planetary gear reducer, this embodiment also provides a contact ball bearing structure design at the output end planet carrier. Figure 1 As shown:

[0079] The planet carrier 203 of the third-stage planetary gear reduction mechanism is rotationally connected to the inner gear housing 100 via at least one row of contact ball bearing structures (in this embodiment, the contact ball bearing structure is one row), and the contact ball bearing structure realizes the axial positioning of the planet carrier in the third-stage planetary gear reduction mechanism;

[0080] The contact ball bearing structure includes M first inner ring outer raceways 2031 arranged along the axial direction on the outer surface of the planet carrier 203 of the third-stage planetary gear reduction mechanism, and M first outer ring inner raceways 1001 corresponding to the M first inner ring outer raceways 2031 are arranged on the inner wall of the inner gear housing 100 along the axial direction; M≥1;

[0081] M steel ball installation raceways 500 are formed between the M first inner ring outer raceways 2031 and the M first outer ring inner raceways 1001 ; a plurality of first steel balls 600 are arranged in the circumferential direction in each steel ball installation raceway.

[0082] like Figure 2 and Figure 4 As shown, in order to facilitate the processing and installation of the contact ball bearing structure, in this embodiment, at least one axial hole 2032 is provided on the planetary carrier 203 of the third-stage planetary gear reduction mechanism, and M ball loading holes 2033 are provided at the positions corresponding to the positions of the axial hole 2032 and the first inner ring outer raceway 2031, and each ball loading hole 2033 is provided with an anti-escape structure 700 for preventing the ball from escaping.

[0083] There are many forms of anti-escape structure to choose from. Its purpose is to prevent the first steel ball 600 from falling out of the ball filling hole 2033 during operation, especially under large load conditions after processing. A better way is that not only will the first steel ball 600 not fall out of the ball filling hole 2033 during operation, but also the raceway can be opened to take out the first steel ball 600 when maintenance is needed.

[0084] The ball filling hole 2033 should be set perpendicular to the steel ball mounting raceway 500, that is, perpendicular to the axial hole 2032, which is the best. It can also be set obliquely, but when it is set obliquely, firstly, the processing cost will increase, and secondly, there is a risk of reducing the bearing stiffness.

[0085] Based on the above conditions, two specific structures of the anti-escape structure are provided for reference. The first structure is adopted in this embodiment:

[0086] 1. If Figure 5 As shown, a pin 701 is arranged in the ball filling hole 2033, and a limiting hole 702 is arranged on the planetary carrier 203 of the third-stage planetary gear reduction mechanism. The limiting hole 702 is connected with the ball filling hole 2033, and the pin 701 is positioned by installing a tightening screw 703 in the limiting hole 702. The limiting hole 702 is preferably parallel to the central axis of the axial hole 2032, so that the force is relatively balanced when the limiting and tightening is performed. The pin 701 is fixed. If the contact ball bearing structure is multi-row, the limiting holes 702 should be staggered, and the limiting holes closer to the center row are deeper. In this case, the axial hole 2032 should be equal to the number of raceways.

[0087] The processing and assembly method of the contact ball bearing structure in this embodiment is as follows:

[0088] Step 1: Processing M first outer ring inner raceways 1001 on the inner gear housing 100;

[0089] Step 2: The axial hole 2032, M ball loading holes 2033 and M limiting holes 702 are machined on the planet carrier 203 of the third-stage planetary gear reduction mechanism; after the axial hole 2032, M ball loading holes 2033 and M limiting holes 702 are manufactured, the pins 701 are respectively installed in the M ball loading holes 2032, and then the limiting devices are installed through the limiting holes 702 to fix the pins 701. After fixing, the pins 701 are machined so that the ends of the pins 701 away from the inner raceway 1001 of the first outer ring are coplanar with the hole wall of the axial hole 2032;

[0090] Alternatively, first make M ball filling holes 2032 and M limiting holes 702 on the planet carrier 203 of the third-stage planetary gear reduction mechanism; after the M ball filling holes 2032 and the M limiting holes 702 are made, the pins 701 are all installed in the M ball filling holes 2032, and then the limiting devices are installed through the limiting holes 702 to fix the pins 701. After fixing, the axial holes 2032 are made so that the end of each pin 701 away from the first outer ring inner raceway 1001 is coplanar with the hole wall of the axial hole 2032;

[0091] Step 3: Process the M first inner ring outer raceways 2031 on the planet carrier 203 of the third-stage planetary gear reduction mechanism, and at the same time process the pins 701 extending into the first inner ring outer raceway 2031 through the ball filling holes 2032, so that one end of each pin 701 extending into the first inner ring outer raceway 2031 is coplanar with the wall of the first inner ring outer raceway 2031; after the production is completed, remove the pins 701 and the limiting device;

[0092] Step 4: Load the first steel ball 600. There are two ways to do this:

[0093] Method 1:

[0094] Step 4.1: Load a first steel ball 600 into a raceway through the ball loading hole 2032 made in step 3; grease may be applied to the first steel ball 600 and / or the raceway to reduce the difficulty of installation;

[0095] Step 4.2: Rotate the inner gear housing 100 so that the first steel ball 600 loaded in step 4.1] is offset from the ball loading hole 2032;

[0096] Step 4.3: Load a first steel ball 600 into the raceway through the ball loading hole 2032;

[0097] Step 4.4: loop steps 4.2 to 4.3 until all the first steel balls 600 are loaded into the raceway;

[0098] Step 4.5: Repeat steps 4.1 to 4.4 to load other raceways until all are loaded;

[0099] Method 2:

[0100] Step 4.1: Load a first steel ball 600 into each raceway through the ball loading hole 2032 made in step 3;

[0101] Step 4.2: Rotate the inner gear housing 100 so that the first steel balls 600 loaded in step 4.1 are staggered from the ball loading holes 2032;

[0102] Step 4.3: Load a first steel ball 600 into each rolling path through the ball loading hole 2032;

[0103] Step 4.4: loop steps 4.2 to 4.3 until all first steel balls 600 are loaded into each raceway;

[0104] Step 5: Install the pin shaft 701 into the ball filling hole 2032 to seal it, and insert the limiting device into the limiting hole 702 to fix the pin shaft 701.

[0105] 2. An isosceles trapezoidal elastic sleeve is arranged in the ball filling hole, with the bottom surface with a larger area of ​​the sleeve facing the center of the bearing, and the top surface with a smaller area facing the outer raceway of the first inner ring. The diameter of the larger area is larger than the diameter of the first steel ball, and the diameter of the smaller area is smaller than the diameter of the first steel ball. However, the difference needs to ensure that the deformation generated during installation can squeeze the first steel ball in, and at the same time, the strength can ensure that the first steel ball is not squeezed out when the first steel ball is subjected to force at this position during operation.

[0106] In this embodiment, when the number M of the steel ball installation raceway 500 is 1: the steel ball installation raceway 500 includes four eccentric arcs, each of which occupies 1 / 4 of the circumference of the cross section, and the first steel ball 600 is in point contact with the four arcs of the steel ball installation raceway 500. Figure 6 As shown, each first outer ring inner raceway 1001 is composed of a first arc A1 and a second arc A2 that are eccentrically arranged, and the first steel ball 600 is in point contact with the first arc A1 and the second arc A2, respectively, and the contact points here are recorded as S1 and S2 respectively; each first inner ring outer raceway 2031 is composed of a third arc A3 and a fourth arc A4 that are eccentrically arranged, and the first steel ball 600 is in point contact with the third arc A3 and the fourth arc A4, respectively, and the contact points here are recorded as S3 and S4 respectively, thereby forming a four-point contact ball bearing structure. In order to further reduce steel ball wear, the contact points of the first steel ball 600 with the first arc, the fourth arc, and the center of the first steel ball 600 are collinear (such as Figure 6 As shown, that is, S1, S4, O are collinear); the contact points of the first steel ball 600 with the second arc, the third arc, and the center of the first steel ball 600 are collinear (as shown Figure 6 As shown, points S2, S3 and O are collinear).

[0107] When the number M of steel ball installation raceway 500 is 2, there are three structural forms:

[0108] The first form is:

[0109] The first steel ball installation raceway includes four eccentric arcs, each of which occupies 1 / 4 of the circumference of the cross section; the second steel ball installation raceway includes four eccentric arcs, each of which occupies 1 / 4 of the circumference of the cross section; the arc of the first steel ball installation raceway is the same as the arc of the second steel ball installation raceway, and the first steel ball 600 and the four arcs of the first steel ball installation raceway, as well as the first steel ball 600 and the four arcs of the second steel ball installation raceway are all point contacts, such as Figure 7 As shown;

[0110] The second and third forms are:

[0111] The first steel ball installation raceway includes two eccentric arcs, each of which occupies 1 / 2 of the circumference of the cross section; the second steel ball installation raceway includes two eccentric arcs, each of which occupies 1 / 2 of the circumference of the cross section; the arc of the first steel ball installation raceway and the arc of the second steel ball installation raceway are mirror images, and the structure presented is a back-to-back mirror image (such as Figure 8 ), or face-to-face mirroring (as Fig. 9 shown).

[0112] like Fig.10 As shown, when the number M of steel ball mounting raceways is 3, the first steel ball mounting raceway includes two eccentric arcs, each of which occupies 1 / 2 of the circumference of the cross-section; the second steel ball mounting raceway includes four eccentric arcs, each of which occupies 1 / 4 of the circumference of the cross-section, and the first steel ball is in point contact with the four arcs of the second steel ball mounting raceway; the third steel ball mounting raceway includes two eccentric arcs, each of which occupies 1 / 2 of the circumference of the cross-section; the arc of the first steel ball mounting raceway and the arc of the third steel ball mounting raceway are mirrored.

Claims

1. A planetary gear reducer with same-side input and output and a hollow structure, comprising an inner gear housing and N-stage planetary gear reduction mechanisms arranged in sequence along the axial direction of the inner gear housing; N≥2; each stage of the planetary gear reduction mechanism comprises a sun gear, a planetary gear, a planet carrier and a planetary shaft; Features: It also includes input gear, center sleeve, baffle cover and steel ring; The sun gears of each level of planetary gear reduction mechanism have a central through hole, and the center of the planet carrier of the Nth level planetary gear reduction mechanism is provided with a multi-step through hole; The central sleeve is coaxially installed in the central through hole of each level of sun gear and the through hole of the multi-level step, and the central sleeve is respectively kept in clearance fit with the central through hole of each level of sun gear; one end of the central sleeve is coaxially fixedly connected with the input gear located in the large diameter hole in the through hole of the multi-level step, and the other end of the central sleeve is pressed and fitted with the blocking cover, and the blocking cover is fixedly connected with the sun gear of the first-stage planetary gear reduction mechanism; A bearing for supporting and positioning is installed on the outer surface of the central sleeve and at the position of the middle diameter hole corresponding to the multi-step through hole, and the interior of the central sleeve is a wire passage for the cable to pass through; A retaining ring is fixedly arranged on the sun gear in the first-stage planetary gear reduction mechanism, and the end face of the retaining ring contacts the end face of the planetary gear in the first-stage planetary gear reduction mechanism, and is used for axial positioning of the planetary gear in the first-stage planetary gear reduction mechanism.

2. The planetary gear reducer with same-side input and output and a hollow structure according to claim 1, characterized in that: The blocking cover includes a circular portion and a tapered cylinder portion arranged on the circular portion; the central through hole of the sun gear in the first-stage planetary gear reduction mechanism has a tapered hole section; the tapered cylinder portion and the tapered hole section form a conical surface match; the screw passes through the circular portion and is threadedly connected to the sun gear of the first-stage planetary gear reduction mechanism.

3. The planetary gear reducer with same-side input and output and having a hollow structure according to claim 1 or 2, characterized in that: In the 2nd to Nth stage planetary gear reduction mechanisms, the sun gear is provided with a first external tooth and a second external tooth, and the tooth height of the first external tooth is greater than the tooth height of the second external tooth; the first external tooth is meshed with the planetary gear of the current stage, and the second external tooth is key-connected with the planetary carrier of the previous stage; The end face of the previous stage planet carrier contacts the end face of the first external tooth on the current stage sun gear, and at the same time forms a micro gap with the end face of the current stage planet gear; The planet shaft of each stage of the planetary gear reduction mechanism is interference fit with the planet shaft mounting hole on the planet carrier, and the planet wheel and the planet carrier of the Nth stage planetary gear reduction mechanism contact each other to realize the axial positioning of the planet wheel in the Nth stage planetary gear reduction mechanism.

4. The planetary gear reducer with same-side input and output and having a hollow structure according to claim 3, characterized in that: The planet carrier of the Nth-stage planetary gear reduction mechanism is rotationally connected to the inner gear housing via at least one row of contact ball bearing structures, and the contact ball bearing structure realizes axial positioning of the planet carrier in the Nth-stage planetary gear reduction mechanism; The contact ball bearing structure includes M first inner ring outer raceways arranged along the axial direction on the outer surface of the planet carrier of the N-th stage planetary gear reduction mechanism, and M first outer ring inner raceways corresponding to the M first inner ring outer raceways are arranged on the inner wall of the inner gear housing along the axial direction; M≥1; M steel ball installation raceways are formed between the M first inner ring outer raceways and the M first outer ring inner raceways; a plurality of first steel balls are arranged in each steel ball installation raceway along the circumferential direction; At least one axial hole is arranged on the planet carrier of the Nth stage planetary gear reduction mechanism, and M ball loading holes are arranged at positions corresponding to the axial hole and the outer raceway of the second inner ring, and each ball loading hole is provided with an anti-escape structure to prevent the ball from escaping.

5. The planetary gear reducer with same-side input and output and having a hollow structure according to claim 4, characterized in that: A limiting hole is also provided on the planet carrier of the Nth-stage planetary gear reduction mechanism, and the limiting hole is connected to the ball loading hole; a limiting device for preventing the anti-escape structure from moving is provided in the limiting hole.

6. The planetary gear reducer with same-side input and output and having a hollow structure according to claim 5, characterized in that: The limiting hole is a screw hole parallel to the axial hole, and the limiting device is a tightening screw.

7. The planetary gear reducer with same-side input and output and having a hollow structure according to claim 4, characterized in that: When M is 1: the steel ball mounting raceway includes four eccentric arcs, each of which occupies 1 / 4 of the circumference of the cross section, and the second steel ball is in point contact with the four arcs of the steel ball mounting raceway.

8. The planetary gear reducer with same-side input and output and a hollow structure according to claim 4, characterized in that: When M is 2, The first ball installation raceway consists of four eccentric arcs, each of which occupies 1 / 4 of the cross-section circumference; The second ball installation raceway consists of four eccentric arcs, each of which occupies 1 / 4 of the circumference of the cross section; The arc of the first steel ball mounting raceway is the same as the arc of the second steel ball mounting raceway, and the second steel ball is in point contact with the four arcs of the first steel ball mounting raceway, as well as the second steel ball and the four arcs of the second steel ball mounting raceway.

9. The planetary gear reducer with same-side input and output and a hollow structure according to claim 4, characterized in that: When M is 2, The first ball installation raceway consists of two eccentric arcs, each of which occupies 1 / 2 of the cross-section circumference; The second ball installation raceway consists of two eccentric arcs, each of which occupies 1 / 2 of the circumference of the cross section; The arc of the first steel ball mounting raceway and the arc of the second steel ball mounting raceway are mirror images.

10. The planetary gear reducer capable of same-side input and output and having a hollow structure according to claim 4, characterized in that: When M is 3, The first ball installation raceway consists of two eccentric arcs, each of which occupies 1 / 2 of the cross-section circumference; The second steel ball installation raceway includes four eccentric arcs, each of which occupies 1 / 4 of the circumference of the cross section. The second steel ball is in point contact with the four arcs of the second steel ball installation raceway. The third ball installation raceway consists of two eccentric arcs, each of which occupies 1 / 2 of the circumference of the cross section; The arc of the first steel ball installation raceway and the arc of the third steel ball installation raceway are mirror images.

Images