JP2004138094A - Speed reducer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent coming-off of an output shaft or the like from a casing of a speed reducer even when an impact load is applied at the time of collision or the like. <P>SOLUTION: On a main body 36A of a casing 36, a claw-shaped circular plate 70 having a projection 70A projected radially inward is provided through a bolt 72. The projection 70A of this plate 70 is in contact with neither of a first support block 40 nor a member integrated with the first support block 40 (unillustrated). A counter part 40A is formed on the first support block 40 facing the projection 70A axially inward of the casing. For the facing part 40A, its outer diameter d1 is set to be larger than inner diameter D1 of the projection. Both parts 70A and 40A are partly overlapped when seen in an axial direction. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a speed reducer, and more particularly to a speed reducer suitable for use for driving a joint of a robot and the like, in which an extremely strong load may be applied to the speed reducer itself due to a collision accident or the like.
[0002]
[Prior art]
In recent years, various types of industrial robots have been used at various manufacturing sites. FIG. 7 conceptually shows the structure of a typical industrial robot.
[0003]
A rotary head 4 is mounted on the fixed base 2 so as to be rotatable around an S axis, and rotates about the S axis via a first servomotor 6 and a first reduction gear 8. A first arm 10 is mounted on the upper part of the rotary head 4 so as to be swingable back and forth around the L axis, and swings back and forth about the L axis via a second servomotor 12 and a second reduction gear 14. . A second arm 16 is mounted on the upper part of the first arm 10 so as to be vertically swingable around a U axis, and swings up and down around the U axis via a third servomotor 18 and a third reduction gear 20. I do. With the above configuration, the end effector E can be driven three-dimensionally (for example, see Patent Document 1).
[0004]
The first to third reduction gears 8, 14, and 20 are required to have a function of converting the output of the first to third servo motors 6, 12, and 18 into low-speed and high-torque, and generally have an eccentric oscillating internal engagement mesh. A reduction gear using a planetary gear mechanism or a flexibly meshing internal meshing planetary gear mechanism is used.
[0005]
In general, such a reduction gear used for driving a joint of an industrial robot is designed to withstand the impact even when the robot collides with something due to an operation error or the like. In addition, the transmission capacity or the safety factor is set higher than that of the reduction gear for normal use.
[0006]
[Patent Document 1]
JP-A-11-300681
[Problems to be solved by the invention]
However, when the robot is operating in an actual factory or the like, sometimes a strong impact (load) far more than expected is applied. That is, in general, in the speed reducer, the shaft and components close to the input shaft are formed thin (small), while the shafts and components close to the output shaft are formed thick (large). This is because the closer the output shaft is, the more the rotation of the input shaft is decelerated and the larger the torque to be handled.
[0008]
However, these handling torques are based on the premise that each shaft or component "rotates" in a predetermined direction under the expected load, so that a shocking load such as at the time of a collision may be instantaneous. When the rotation is applied from outside the speed reducer, each part of the rotating system cannot perform a predetermined rotation, and a torque greatly exceeding expectation may be directly applied to each part. As a result, there is a possibility that a shaft or a pin (for example, a carrier pin) or the like which is in a severe condition in terms of strength may break or break.
[0009]
Further, in this case, if the large part such as the output shaft loses its supporting base due to the breakage and falls off from the casing, so-called secondary damage occurs in which the nearby parts are destroyed due to the fallout. It can be lost.
[0010]
The present invention, as one of the answers to such a problem, does not simply increase the capacity or size of the speed reducer so as to withstand a large impact, but decelerates even if a strong impact is applied. Even if a part of the inside of the machine is destroyed, the components that make up the speed reducer are structurally avoided from falling off to prevent secondary damage, and the entire speed reducer, and thus the speed reducer is mounted It is an object of the present invention to further enhance the safety of the entire device (for example, a robot device).
[0011]
[Means for Solving the Problems]
The present invention relates to a speed reducer in which a shaft that rotates relative to the casing is exposed from an end surface of the casing, wherein, at an axial end portion of the casing, a protrusion protruding inward in a radial direction is provided on the shaft or the shaft. The outer diameter of the shaft or a part of the member integrated with the shaft is set to be larger than the inner diameter of the protrusion. The above-mentioned problem has been solved by forming a facing portion facing the inside in the casing axial direction.
[0012]
In a reduction gear of a type in which a casing is fixed and a shaft (for example, an output shaft) exposed from an end of the casing rotates, the shaft or a member integrated with the shaft is a shaft inside the casing. If it breaks, it may lose its supporting or holding base and fall out of the casing of the speed reducer.
[0013]
On the other hand, in a reduction gear of a type in which the shaft exposed from the end of the casing is fixed and the casing rotates as a so-called frame member, only this shaft or a part integrated with the shaft is fixed. The entire reduction gear including the casing may remain on the member side and fall off.
[0014]
In the present invention, attention is paid to this point, and even if a part of the shaft or the like in the speed reducer is broken due to, for example, an excessive load at the time of a collision, the shaft exposed from the end face of the casing is separated from the casing. By structurally preventing such damage, the safety of persons in the vicinity is ensured, and damage to machines and buildings existing in the vicinity is prevented.
[0015]
That is, in the present invention, a projection is provided at the axial end of the casing to project inward in the radial direction, and a part of the shaft or a member integrated with the shaft, which is exposed from the casing, is provided with the protrusion. The inner diameter of the protruding portion is set smaller than the outer diameter of the opposing portion so as to oppose the inner side in the casing axial direction. This projection prevents the shaft or the member integrated with the shaft from falling off the casing even if the inside of the speed reducer is broken.
[0016]
Since this projection is provided in a state in which it does not come into contact with either the shaft or a member integrated with the shaft, there is no adverse effect on the rotation system of the speed reducer in normal times.
[0017]
The projection may be formed by, for example, a plate attached to an end surface of the casing. Alternatively, it can be formed by a plate fitted on the inner periphery of the casing.
[0018]
The specific reduction mechanism of the reduction gear to which the present invention is applied is not particularly limited.For example, the reduction mechanism includes a planetary gear reduction mechanism having an internal gear and an external gear having a small difference in the number of teeth. On both sides in the axial direction of the planetary gear reduction mechanism, first and second support blocks are arranged in a state where they are connected to each other via a carrier pin that passes through the planetary gear reduction mechanism in the axial direction. It is particularly effective to apply the present invention to a speed reducer in which at least one of the second support blocks functions as the shaft or a member integrated with the shaft.
[0019]
As a modified example of the present invention, a planetary gear reduction mechanism having an internal gear and an external gear having a small difference in the number of teeth is provided, and the relative rotation between the internal gear and the external gear is set in the axial direction. The external gear is taken out to first and second support blocks disposed on both sides in the axial direction of the external gear through internal pins penetrating the external gear, and the first and second support blocks are axially penetrated through the external gear. In the speed reducer connected to each other via a carrier pin, each of the first and second support blocks is provided with a protrusion protruding inward in a radial direction, and the outer periphery of the inner pin and the respective protrusion is provided. It is conceivable that the reduction gear is formed with opposing projections that are axially opposed to the projections at the positions corresponding to the outside in the axial direction of the portions or the positions corresponding to the inside in the axial direction of the respective projections.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0021]
FIG. 1 shows a speed reducer according to an embodiment of the present invention.
[0022]
For convenience, the schematic configuration of the speed reducer 30 will be described. The speed reducer 30 has a planetary gear speed reduction mechanism RG, and corresponds to a speed reducer called a so-called eccentric oscillating type internally meshing planetary gear structure. The speed reducer 30 includes an input shaft 32, an external gear 34 eccentrically oscillating and rotating about the input shaft 32, a small difference in the number of teeth from the external gear, and fixed to a casing 36 and external gears. An internal gear 38 in which the gear 34 internally meshes, first and second support blocks 40 and 41 disposed on both axial sides of the external gear 34, and an external gear 34 penetrates in the axial direction. An eccentric shaft (inner pin) 50 for transmitting relative rotation of the internal gear 38 and the external gear 34 to the first support block 40 and the second support block 41 is provided.
[0023]
The input shaft 32 has a hollow portion 42 into which an output shaft of a motor (not shown) is inserted, and a pinion 44 is formed at the tip. Three driven gears 46 arranged in the circumferential direction mesh with the pinion 44. An eccentric shaft 50 is engaged with a central portion of each driven gear 46 via a spline 52. Further, two eccentric bodies 48 are formed integrally with each eccentric body shaft 50.
[0024]
A through-hole 54 is formed in the two external gears 34, and the eccentric body 48 of the eccentric shaft 50 is engaged with the through-hole 54 through a bearing 56. The eccentric body 48 provided on each eccentric body shaft 50 has the same eccentric phase for each external gear 34.
[0025]
The eccentric shaft (internal pin) 50 is supported by the first support block 40 and the second support block 41 arranged on both axial sides of the external gear 34 via bearings 57 and 58, and the internal gear 38 The relative rotation of the external gear 34 (in this case, the rotation component of the external gear 34) is transmitted to the first and second support blocks 40 and 41.
[0026]
The first support block 40 and the second support block 41 are respectively entirely supported by the casing 36 via bearings 70 and 72 so as to be relatively rotatable, and via a carrier pin 68 that passes through the external gear 34 in the axial direction. Integrated. In the case of the present embodiment, of the two support blocks 40 and 41, the first support block 40 functions as a so-called output shaft.
[0027]
The end face of the first support block 40 is exposed from the end 36A of the casing 36, and the end face of the first support block 40 is located on substantially the same plane as the end face 68A of the carrier pin 68. Further, a bolt hole 76 is formed in the carrier pin 68 from the end face 68A in the axial direction, and a bolt (not shown) in which a flange of a driven member (a counterpart machine) penetrates the bolt hole 76. Is screwed into the driven member via the step 68B of the carrier pin 68.
[0028]
In addition, the second support block 41 is firmly connected to the carrier pin 68 by another step 68C of the carrier pin 68 and a bolt 77 with a flange. Therefore, the first and second support blocks 40 and 41 do not fall off the casing 36 during normal operation. However, in this embodiment, measures are taken as follows in the event that the carrier pin 68 is broken.
[0029]
That is, the main body 36B of the casing 36 has a hook-shaped ring-shaped plate 70 having a projection 70A projecting radially inward at an axial end 36A (the left end in FIG. 1) of the main body 36B. Are provided via bolts 72. The protruding portion 70A of the plate 70 is provided so as not to contact either the first support block 40 or a member integrated with the first support block 40.
[0030]
On the other hand, the first support block 40 is formed with an opposing portion 40A that opposes the protrusion 70A on the inner side in the casing axial direction. The outer diameter d1 of the facing portion 40A is set to be larger than the inner diameter D1 of the projection 70A. That is, the projection 70A and the facing portion 40A partially overlap each other when viewed from the axial direction.
[0031]
Next, the operation of the speed reducer 30 will be described.
[0032]
When the input shaft 32 rotates by rotation of a motor (not shown), the eccentric shaft 50 rotates via the pinion 44 and the driven gear 46. As a result, the eccentric body 48 provided integrally with the eccentric shaft 50 rotates eccentrically with respect to the axis Eo of the eccentric shaft 50. Since the three eccentric bodies 48 engaged with the external gears 34 via the bearings 56 have the same eccentric phase for each external gear 34, each external gear 34 has an internal tooth. It swings and rotates while meshing with the gear 38. As a result, the phase between the external gear 34 and the internal gear 38 changes every time each eccentric body 48 makes one rotation, corresponding to the “difference” between the number of teeth of the external gear 34 and the number of teeth of the internal gear 38. Relatively shifted. Therefore, the three eccentric shafts 50 slowly revolve around the input shaft 32 (corresponding to the external gear) while being supported by the first and second support blocks 40 and 41 (corresponding to the shift). In this case, the rotation of the eccentric shaft 50 (the rotation component of the external gear 34) is transmitted to the first and second support blocks 40 and 41, and the speed of the reduction gear 30 is reduced from the first support block 40 side. Taken as output.
[0033]
By the way, according to the inventor's experiments or observations with the actual machine, if any accident such as a collision occurs, in the speed reducer having such a structure, the carrier pin 68 that looks strong at first glance is more eccentric. It has been confirmed that the shaft (inner pin) 50 is more easily broken than the shaft (inner pin) 50. This is because the carrier pin 68 handles a large torque which has been originally decelerated, and is connected to the first and second support blocks 40 and 41 in a state where slippage is not allowed, that is, in a completely fixed state. Therefore, an impact torque (reaction torque) is directly applied from the side of the first support block 40 (the side of the counterpart machine) in a state where the second support block 41 cannot substantially rotate. It seems to be related.
[0034]
Here, if the carrier pin 68 is broken, the first support block 40 loses its support base, so that the first support block 40 is moved out of the casing 36 (in a conventional structure without special consideration). May fall off.
[0035]
However, in the speed reducer 30 according to this embodiment, the ring-shaped plate 70 having the projection 70A is attached to the axial end of the casing 36, and the projection 70A is further provided on the first support block 40 side. An opposing portion 40A is formed to oppose. The outer diameter d1 of the opposing portion 40A is set to be larger than the inner diameter D1 of the protruding portion 70A, and the protruding portion 70A and the opposing portion 40A partially overlap each other when viewed from the axial direction.
[0036]
Therefore, the first support block 40 cannot jump out of the casing 36 due to the presence of the facing portion 40A and the protrusion 70A. Therefore, even if the carrier pin 68 is broken, for example, the first support block 40, which is the output shaft, does not fall out of the casing 36, and secondary damage due to the drop of the first support block 40 occurs. Can be prevented.
[0037]
Since a motor (not shown) connected to the input shaft 32 is disposed on the side of the second support block 41, it is considered that there is almost no possibility of dropping.
[0038]
Since the projection 70A is provided so as not to contact the first support block 40 or any of the members integrated with the first support block, the projection 70A does not generate any rotation with respect to the rotation of the reduction gear during normal operation. Has no effect.
[0039]
FIG. 3 schematically shows (an example of) another embodiment of the present invention.
[0040]
Note that the reference numerals of the respective units are newly added for the sake of convenience in explaining FIG.
[0041]
The variation in the column direction (vertical axis direction) of the table shown in FIG. 3 shows a modification for forming the projection PR on the casing C side. The projection PR on the casing C side can be formed by a configuration such as (1) retaining ring PR1, (2) plate PR2 + bolt BL, and (3) washer PR3 + bolt BL. The retaining ring and the washer are included in the concept of the plate in a broad sense.
[0042]
The method (1) using the retaining ring PR1 has a small number of parts and is easy to assemble. In the method (2) using the plate PR2 and the bolts BL, since the strength of the protruding portion is high, the effect of preventing falling off is high. In the method (3) using the washer PR3 and the bolt BL, both commercial and general-purpose components can be used, so that the cost is low.
[0043]
On the other hand, the variation in the row direction (horizontal axis direction) of the table shown in FIG. 3 shows a modification for forming the facing portion FA on the shaft SH (or a member integral with the shaft) SH. Regarding the formation of the facing portion FA on the shaft SH side, (A) a method of providing a projection FA1 on the outer periphery of the axial end of the shaft SH, and (B) the shaft between the shaft SH and the protrusion PR on the casing C side. A method of interposing a plate FA2 integrated with the SH (and the counterpart machine MM), or (C) using a part of the driven member of the counterpart machine MM integrated with the output shaft as a part of the speed reducer, A method of forming the facing portion FA3 on the side of the counterpart machine MM may be considered.
[0044]
In the method (A), the number of parts does not need to be increased, so that the assembling is easy and the parts are dedicated. However, the thickness of the facing part FA in the axial direction is appropriately set according to the application. it can. The method (B) is excellent in that the shaft (or a product integral with the shaft) SH can be used as it is as a conventional standard product (product without a corresponding portion). The method (C) can also use the same type (standard) standard product as the shaft SH (or a product integral with the shaft) SH, and also has the advantage that the axial length of the reduction gear does not increase. .
[0045]
The structure according to the embodiment shown in FIGS. 1 and 2 corresponds to a further modification of the structure (2)-(A) in FIG. 3, and a key-shaped ring-shaped plate 70 thick in the axial direction. As described above, it is possible to grasp that the casing 36B of the casing 36 is such that a casing (standard product) conventionally used can be diverted as it is.
[0046]
As described above, in the present invention, the gist of the present invention is that the protrusion is directed radially inward from the casing side so that the shaft that rotates relative to the casing or a member integrated with the shaft does not separate from the casing. It is sufficient that an opposing portion that opposes this protrusion on the shaft or a member integrated with the shaft on the inner side in the casing axial direction is formed, and is not limited to the example of FIG. 3. The facing portion FA only needs to have an outer diameter larger than the inner diameter of the protrusion PR, and does not necessarily need to protrude from the outer periphery of the shaft SH.
[0047]
In FIG. 3, [New] indicates a product newly manufactured for implementing the present invention, and [Sub] indicates a component which can be diverted from a conventional component (member) as it is.
[0048]
4 to 6 show another embodiment of the present invention.
[0049]
As shown in FIGS. 4 and 5, also in this embodiment, the first and second support blocks 140 and 141 that rotate relative to the casing 136 are exposed from the end surface 136A of the casing 136 as in the previous embodiment. Related to the speed reducer 130. The speed reducer 130 has a planetary gear speed reduction mechanism RG2 having an internal gear 138 and an external gear 134 having a small difference in the number of teeth as its speed reduction mechanism, and controls the relative rotation of the internal gear 138 and the external gear 134. The external gear 134 is taken out via an eccentric shaft (inner pin) 150 penetrating in the axial direction to first and second support blocks 140 and 141 arranged on both sides in the axial direction of the external gear 134. The first and second support blocks 140 and 141 are connected to each other via a carrier pin 168 that passes through the external gear 134 in the axial direction.
[0050]
In this embodiment, not only the first support block 140 but also the second support block 141 is provided with a fall prevention measure. In order to prevent the second support block 141 from falling off, one of the methods is to form a structure similar to the above-described configuration regarding the prevention of the first support block 140 from falling off on the second support block 141 side. It is, of course, effective.
[0051]
However, in this embodiment, a slightly different configuration is adopted by utilizing the fact that similar drop-off prevention mechanisms are arranged on both sides. That is, retaining rings (projections) 140A, 141A protruding inward in the radial direction are disposed on the first and second support blocks 140, 141, respectively (ends in the axial direction), and the eccentric body shaft (the inner pin) is provided. The plate (opposing protruding portion) 150A facing the outer periphery of the protruding portion 140A, 141A (or a position corresponding to the inner side of the protruding portion 140A, 141A in the axial direction) on the outer periphery of the protruding portion 140A, 141A. (Via the stop washer 150B).
[0052]
As the retaining rings 140A and 141A as the projections, those conventionally provided for positioning the bearings of the first and second support blocks 140 and 141 can be used.
[0053]
As shown in FIG. 6, it is assumed that, for example, the carrier pin 168 is broken at a portion indicated by reference numeral BK in FIG. 6 due to application of some excessive impact (load). Due to this break, the first support block 140 loses its support base and tends to fall out of the casing 136. However, the retaining ring (projection) 140A formed on the first support block 140 becomes eccentric shaft (inner pin) 150. Since it is caught by the plate (opposing projection) 150A formed in the above, it is prevented that it actually falls off.
[0054]
Other configurations are basically the same as those of the previous embodiment. Therefore, in FIG. 4 to FIG. I do.
[0055]
In the above-described embodiment, a so-called eccentric oscillating type internally meshing planetary gear structure is adopted as the structure of the reduction gear. However, the structure of the reduction gear is not particularly limited in the present invention. For example, a central input type eccentric oscillating type internally meshing planetary gear structure having an eccentric body on the outer periphery of the input shaft and incorporating an external gear in the eccentric body may be used. Furthermore, a simple planetary gear structure, a parallel shaft gear structure, or an orthogonal gear structure such as a bevel gear or a hypoid gear may be used.
[0056]
Further, the reduction gear according to the present invention is not limited to an industrial robot for use, but may be a reduction gear for some reason, for example, when the reduction gear itself is mounted on a moving object such as a vehicle. It is equally applicable to applications in which a very large impact load may be applied.
[0057]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, even if a strong shock is applied and a part in a speed reducer is destroyed, components etc. which comprise a speed reducer are structurally avoided from falling off, and secondary damage is prevented beforehand. As a result, an excellent effect can be obtained that the safety of the entire reduction gear and, further, the whole of the device (for example, a robot device) on which the reduction gear is mounted can be further improved.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a speed reducer according to an embodiment of the present invention. FIG. 2 is a side view of the speed reducer as viewed from the direction of arrow II in FIG. 1. FIG. FIG. 4 is a chart schematically showing an example. FIG. 4 is a longitudinal sectional view of a speed reducer according to another embodiment of the present invention. FIG. 5 is a side view of the speed reducer of FIG. FIG. 7 is a longitudinal sectional view showing a state in which a carrier pin of the reduction gear of FIG. 4 is broken. FIG. 7 is a conceptual diagram showing a schematic structure of an industrial robot.
30, 130: Reducer 32: Input shaft 34, 134 ... External gear 36, 136 ... Casing 38, 138 ... Internal gear 40, 140 ... First support block 41, 141 ... Second support block 46 ... Follower gear 48 ... eccentric bodies 50 and 150 eccentric shaft 58 ... external teeth 70 ... plates 70A, 140A and 141A ... projections 36A ... facing parts 150A ... facing projections

Claims (6)

In a speed reducer in which a shaft that rotates relative to the casing is exposed from an end surface of the casing,
At the axial end of the casing, a projection protruding inward in the radial direction is provided in a state in which it does not come into contact with either the shaft or a member integrated with the shaft,
The shaft or a member integrated with the shaft, the outer diameter of itself is set to be larger than the inner diameter of the protrusion, and a facing portion facing the protrusion on the inside in the casing axial direction is formed. Speed reducer. In claim 1,
The reduction gear, wherein the projection is formed by a plate attached to an end surface of the casing. 2. The reduction gear according to claim 1, wherein the projection is formed by a plate fitted on an inner periphery of the casing. In any one of claims 1 to 3,
The reduction mechanism of the speed reducer includes a planetary gear reduction mechanism having an internal gear and an external gear having a small difference in the number of teeth, and first and second support blocks are provided on both axial sides of the planetary gear reduction mechanism. Are arranged in a state where they are connected to each other via a carrier pin that passes through the planetary gear reduction mechanism in the axial direction, and at least one of the first and second support blocks is integrated with the shaft or the shaft. A speed reducer characterized in that it functions as a member. In claim 4,
A speed reducer, wherein at least one end face of the first and second support blocks has a mounting hole for mounting a counterpart machine. A planetary gear reduction mechanism having an internal gear and an external gear with a small difference in the number of teeth is provided, and the relative rotation between the internal gear and the external gear is controlled via an internal pin that passes through the external gear in the axial direction. The external gear is taken out to first and second support blocks arranged on both sides in the axial direction of the external gear, and the first and second support blocks are connected to each other via a carrier pin that passes through the external gear in the axial direction. In the reducer,
Each of the first and second support blocks is provided with a protrusion protruding radially inward,
At the outer periphery of the inner pin and at an axially outer corresponding position of each of the projecting portions or at an axially inner corresponding position of each of the projecting portions, opposing projecting portions axially facing the projecting portions are formed. Characterized reduction gear.

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