JP2011002063A - Power transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently form an enlarged opening part capable of avoiding damage in a power source cable and a controlling harness while suppressing a cost rise to the minimum.SOLUTION: A power transmission device 10 has a hollow part H1 penetrating through the entire device in a casing 20, and the power transmission device 10 has a hollow second carrier (flange body) 48 with its own inner peripheral face 48A constituting an end of the hollow part H1 at an axial end thereof. The enlarged opening part EP1 with its inner diameter increasing toward an opening end is formed on the inner peripheral face 48A of the second carrier 48.

Description

  The present invention relates to a power transmission device having a hollow portion that penetrates the entire device.

  In industrial machines such as robots and machine tools, a power transmission device having a hollow portion penetrating the entire device is often used. The hollow portion is used for passing a motor power cable, a control harness, and the like.

  Patent Document 1 discloses an example in which a power transmission device having such a hollow portion is configured by an eccentric oscillating speed reduction mechanism in which an external gear oscillates and rotates inside an internal gear. In this power transmission device, a central tube having a central hole penetrating the entire reduction gear is fixed to the internal gear or the carrier, and at the end of the central hole of the central tube fixed to the internal gear or the carrier, An expanded portion whose diameter increases toward the opening end is formed.

  The center tube 10 has a shape as shown in FIG. 6, and is fitted with an expanded portion 10 </ b> A in which the diameter is enlarged on the inner peripheral side and the internal gear or carrier (not shown) on the outer peripheral side. For this purpose, a fitting surface 10B and a cylindrical portion 10C are provided. By incorporating such a “center tube 10” as a “member for forming the expanded portion 10A”, a cable or a harness (not shown) passing through the center tube 10 is connected to the end of the center tube 10. This reduces the wear and damage caused by rubbing the parts.

JP 2008-89157 A (FIG. 1, FIG. 4, paragraphs [0006] [0021])

  However, in the technique disclosed in Patent Document 1, a center tube 10 having a widened portion 10A whose diameter increases toward the opening end is separately prepared and fixed to an internal gear or a carrier. Since this configuration was adopted, there was a problem that the manufacturing cost increased greatly.

  That is, referring again to FIG. 6, the central tube 10 has an expanded portion 10A whose diameter increases toward the opening end due to its function. Only the vicinity is a thick member in the radial direction. In addition, in order to be fitted and fixed to the internal gear or the carrier, it is necessary to form a fitting surface 10B having a complicated shape on the outer periphery. For this reason, when this is to be manufactured by cutting or the like, for example, the machining allowance of the (long and thin) cylindrical portion 10C is extremely increased, the material yield is lowered, and the machining time is enormous. By combining forging with cutting, etc., and cutting a material with a certain shape, the number of manufacturing steps increases. In addition, when molding by casting, a special mold must be designed and manufactured separately. That is, when trying to actually manufacture the center tube 10 having the expanded portion 10A, the actual situation is that it results in a considerable increase in cost.

  The present invention has been made to solve such a conventional problem, and is capable of effectively protecting a power cable, a harness and the like passed through a hollow portion while avoiding an increase in cost. The problem is to provide a device.

  The present invention relates to a power transmission device having a hollow portion that penetrates the entire device in the axial direction, and the power transmission device forms either a fixed member or an output member of the power transmission device at an axial end portion thereof. In addition, the inner peripheral surface of the flange body includes a hollow flange body that constitutes the end of the hollow portion, and an expanded portion having an inner diameter that increases toward the opening end is formed on the inner peripheral surface of the flange body. The above-described problem is solved by adopting the configuration described above.

  In the present invention, the “flange body” of the power transmission device is effectively used. In the present invention, the “flange body” is a member that is provided at an end portion in the axial direction of the power transmission device and constitutes either a fixing member or an output member of the power transmission device. For example, it is an output member when the casing of the power transmission device is fixed, and a member that is a fixed member when the casing itself rotates (a member that provides a reaction force against the rotation of the casing). For this reason, in any case, the flange body is a member at the axial end portion of the power transmission device that handles a large torque after deceleration. Therefore, the flange body is a large member having a certain thickness in the axial direction and sufficient thickness in the radial direction in terms of its function.

  In the present invention, the flange body, which is a large member, is positively used, and the end of the hollow portion (through a cable or the like) is directly formed by the inner periphery of the flange body, and the flange body On the inner peripheral surface, an expanded portion having an inner diameter that increases as it approaches the opening end is formed.

  Since the flange body is a large member, it is often formed by casting. Therefore, if the “expanded portion” is formed together with the molding (the expanded portion can be formed simultaneously with the molding of the flange body), it is not necessary to prepare a separate mold. Further, even if the expanded portion is formed by cutting or the like, the flange body is a material having a sufficient thickness in the radial direction because of its function. Since it is sufficient to delete a little in the direction, it is simple and there is little waste of materials and processing time.

  ADVANTAGE OF THE INVENTION According to this invention, the expansion part which can avoid damage to a power cable and a control harness can be formed efficiently, suppressing a raise of cost as much as possible.

Sectional drawing of the joint drive device of the robot to which an example of embodiment of this invention was applied Sectional view along arrow II-II in FIG. The principal part expanded sectional view which shows an example of the joint drive device of the robot which concerns on other embodiment of this invention. The principal part expanded sectional view which shows an example of the joint drive device of the robot which concerns on further another embodiment of this invention. The principal part expanded sectional view which shows an example of the joint drive device of the robot which concerns on further another embodiment of this invention. Sectional drawing of the center pipe | tube integrated in order to form an expansion part in the conventional power transmission device

  Hereinafter, an example of an embodiment of the present invention will be described in detail based on the drawings.

  FIG. 1 is a sectional view of a joint drive device (power transmission device) for a robot to which an example of an embodiment of the present invention is applied. FIG. 2 is a cross-sectional view taken along the line II-II in FIG.

  This joint drive device 10 is rotatably supported by a rotating member 14 constituting another part of the robot while being fixed to a base member 12 constituting a part of the robot (not shown). To drive. When the joint drive device 10 is used for joint drive after the second stage, the base member 12 corresponds to a movable member at the previous stage. Therefore, in this case, the base member 12 itself can also move, and the rotating member 14 rotates relative to the (movable) base member 12. Furthermore, the terms base member or rotating member are relative, and if one is viewed as a (fixed) base member, the other is a (rotatable) rotating member. And vice versa. In this embodiment, “rotation” is used not to continue to rotate in the same direction but to “rotate and reciprocate within a fixed range”.

  The joint driving device 10 includes a power source (not shown) fixed and arranged on the base member 12, a motor 16 fixed and arranged on the rotating member 14, and a cable 17 that supplies power from the power source to the motor 16. And a speed reduction mechanism portion 18 having an intermeshing planetary gear structure. The casing 20 of the speed reduction mechanism unit 18 is connected to the base member 12 via bolts 22. Although the relationship between the base member 12 and the rotating member 14 is as described above, in this embodiment, for convenience, the base member 12 is in a fixed state, and therefore the casing 20 connected to the base member 12 is fixed. We will see that it functions as a member.

  A pinion 26 is formed at the tip of the motor shaft 24 of the motor 16 and meshes with the gear 28. The gear 28 is connected to the transmission shaft 32 via the spline 30. A transmission pinion 34 is formed on the transmission shaft 32. The transmission pinion 34 meshes with the transmission internal gear 36.

  Referring also to FIG. 2, the transmission internal gear 36 meshes with the transmission pinion 34 and simultaneously meshes with three eccentric body shaft gears 42A to 42C (only 42A is shown). The eccentric body shaft gears 42A to 42C are integrated with the eccentric body shafts 44A to 44C, respectively. The eccentric body shafts 44A to 44C are rotatably supported by first and second carriers 46 and 48 (which are flange bodies) to be described later via tapered roller bearings 50A to 50C and 52A to 52C (only 50A and 52A are shown). Has been. The eccentric body shaft 44A includes eccentric bodies 60A and 62A that are eccentric from the axis of the eccentric body shaft 44A. The eccentric body shaft 44B includes eccentric bodies 60B and 62B (only 60B is shown in FIG. 2). The eccentric body shaft 44C includes eccentric bodies 60C and 62C (only 60C is shown in FIG. 2). External gears 66 and 68 are fitted to the eccentric bodies 60A to 60C and 62A to 62C, respectively. The eccentric phase difference of the external gears 66 and 68 is 180 °.

  The external gears 66 and 68 are in mesh with the internal gear 72 while swinging. The number of teeth of the external gears 66 and 68 is 118 in this example. The internal gear 72 is integrated with the casing 20. In this embodiment, the internal teeth of the internal gear 72 are constituted by roller-shaped outer pins 74. There should be 120 internal teeth (outer pins 74) of the internal gear 72 originally, but two of them are formed (arranged) alternately thinned out. Even in this configuration, the number of mechanistic internal teeth is 120.

  Here, hollow first and second carriers (flange bodies) 46 and 48 are rotatably supported on the casing 20 via bearings 78 and 80 at both ends of the external gears 66 and 68 in the axial direction. Has been. The casing 20 is integrated with the base member 12 and the bolts 22. The first and second carriers 46 and 48 are connected and integrated by carrier pins 82A to 82F (see FIG. 2). The aforementioned rotating member 14 is connected to the first carrier 46 via a bolt 84. The first and second carriers 46 and 48 can take out the rotation of the external gears 66 and 68 through the eccentric body shafts 44A to 44C. That is, when the casing 20 is viewed as a fixed member, the first and second carriers 46 and 48 as flange bodies constitute an output member.

  In addition, the joint driving device 10 has a hollow portion H1 penetrating in the axial direction at the center in the radial direction. In the present embodiment, the hollow portion H <b> 1 is configured by the second carrier 48, a cylindrical pipe 85 described later, and the rotating member 14. That is, the inner peripheral surface 48A of the second carrier 48 directly constitutes the end of the hollow portion H1. A cable 17 for supplying power from the power source (not shown) to the motor 16 passes through the hollow portion H1. In the joint drive device 10, the power source is disposed on the base member 12 side, and the motor 16 is disposed on the rotating member 14 side. In this arrangement, regardless of the structure of the hollow portion H1, the cable 17 always rotates relative to any part of the members constituting the hollow portion H1.

  Therefore, in this embodiment, the expanded portion EP1 whose inner diameter increases as it approaches the opening end is formed on the inner peripheral surface 48A of the second carrier 48 on the side where the power source of the hollow portion H1 exists. The expanding portion EP1 has a longer radial length R1 than its axial length L1. This is a configuration for avoiding contact between the cable 17 and the inner peripheral surface 48A of the second carrier 48 as much as possible. In this embodiment, almost the entire inner peripheral surface 48A of the second carrier 48 is the “expanded portion EP1”, and the second carrier 48 is manufactured by a single molding operation using the casting including the expanded portion EP1.

  A cylindrical pipe (hollow member) 85 constituting the hollow portion H1 is connected to the starting end of the inner peripheral surface (expanded portion) 48A of the second carrier 48. The cylindrical pipe 85 is sandwiched between the rotating member 14 and the second carrier 48, and O-rings 82 and 84 are interposed between the rotating member 14 and the second carrier 48, respectively. The cylindrical pipe 85 is a cylindrical member formed of steel or casting, and is separate from the second carrier 48 and the rotating member 14, and the inner peripheral portion 85A has a uniform area (expanded). It has a cross section (not open) (the inner peripheral surface is linear in the axial direction). As described above, in the present embodiment, the second carrier 48, the cylindrical pipe 85, and the rotating member 14 constitute the hollow portion H1.

  In the present embodiment, the expanding portion EP1 is formed only on the second carrier 48 side on the base member 12 side to which the power source is fixed, and the expanding portion is on the rotating member 14 side to which the motor 16 is fixed. Is not particularly formed. This is due to the following reasons (A) and (B).

  (A) In this embodiment, since the power source is fixed to the base member 12 that rotates relative to the second carrier 48 (and the cylindrical pipe 85 that rotates integrally with the second carrier 48), the power source is connected to the power source. The cable 17 and the second carrier 48 (and the cylindrical pipe 85) are likely to be rubbed, worn or damaged. Therefore, the expansion part EP1 is formed and the corner of the hollow part H1 is rounded.

  (B) In this embodiment, since the motor 16 is fixed to the rotating member 14, the cable 17 (connected to the motor 16) and the rotating member 14 (and the rotating member 14 are integrated). There is no relative rotation with the cylindrical pipe 85). Therefore, there is almost no possibility that the cable 17 and the rotating member 14 are rubbed. Therefore, the rotating member 14 does not particularly need an expanded portion.

  Next, the operation of the joint drive device 10 will be described.

  The power of the motor 16 reaches a transmission pinion 34 via a pinion 26 formed on the motor shaft 24, a gear 28 that meshes with the pinion 26, and a transmission shaft 32 that is connected to the gear 28 by a spline 30. When the transmission pinion 34 rotates, the transmission internal gear 36 meshed with the transmission pinion 34 rotates, and further, the rotation is distributed to the three eccentric body gears 42A to 42C meshed simultaneously with the transmission internal gear 36. The eccentric body shafts 44A to 44C rotate in the same direction at the same rotational speed. As a result, the external gear 66 is oscillated and rotated while being inscribed in the internal gear 72 by the eccentric bodies 60A to 60C on the eccentric body shafts 44A to 44C. At the same time, the eccentric gears 68A to 62C of the eccentric shafts 44A to 44C are similarly inscribed in mesh with the external gear 66 with a phase difference of 180 ° from the external gear 66. Oscillates and rotates.

  The difference in the number of teeth between the internal gear 72 and the external gears 66 and 68 (the difference between the original number of teeth 120 of the internal gear 72 and the number of teeth 118 of the external gears 66 and 68) is 2, respectively. When the external gears 66 and 68 swing once, the external gears 66 and 68 rotate by the difference in the number of teeth. This rotation component is transmitted to the first and second carriers 46 and 48 (which are flange bodies) via the eccentric shafts 44A to 44C.

  Both the first and second carriers 46 and 48 and the cylindrical pipe 85 rotate integrally. Since the first carrier 46 is integrated with the rotating member 14 via the bolt 84, the rotating member 14 rotates at a rotational speed reduced with the motor 16 disposed on the rotating member 14. .

  Although the cable 17 is connected to the motor 16, the cable 17, the motor 16, and the rotating member 14 rotate together, so that relative rotation between the cable 17 and the rotating member 14 does not occur. The cable 17 hardly occurs, and basically the cable 17 is hardly rubbed or damaged (even if the expanding portion is not particularly formed on the rotating member 14).

  On the other hand, in this embodiment, since the power source is fixed to the base member 12 side, the cable 17 connected to the power source particularly rotates relative to the second carrier 48. However, in this embodiment, the expanded portion EP1 is formed on the entire inner peripheral surface 48A of the second carrier 48, and the cable 17 has a corresponding rigidity. The contact itself with 17 is effectively prevented. Further, even if contact is made, the contact pressure can be drastically reduced (compared to the case where the expanded portion is not formed on the inner peripheral surface 48A), and damage to the cable 17 can be greatly reduced.

  In addition, since the expanded portion EP1 of the second carrier 48 is set such that the radial length R1 is longer than the axial length L1, the contact between the cable 17 and the inner peripheral surface 48 is very unlikely to occur. ing.

  In this embodiment, since the second carrier 48 is originally formed of a casting, it is only necessary to design the mold including the expanded portion EP1 from the beginning. It is unnecessary. In addition, the cylindrical pipe (hollow member) 85 is a simple cylindrical member having a uniform diameter (not expanded), and is low in cost. For this reason, an increase in cost is minimal in manufacturing (although additional processing may be performed when the casting surface becomes rough).

  In the above embodiment, a separate cylindrical pipe (hollow member) 85 is interposed between the second carrier 48 and the rotating member 14, but in the present invention, the second carrier and the rotating member are rotated. It is not specifically limited about what kind of structure it connects between members.

  For example, as shown in FIG. 3, a part of the inner peripheral portion 87 </ b> A of the pipe 87 is extended from the expanded portion EP <b> 3 formed by the inner peripheral surface 89 </ b> A of the second carrier 89. It can also be a shape. In this case, the expanded portions EP2 and EP3 having a large radius of curvature can be easily configured. In addition, since the other structure is the same as that of previous embodiment, it attaches | subjects the same code | symbol to the site | part which has the same or similar function in a figure, and duplication description is abbreviate | omitted. In other embodiments, parts having the same or similar functions are denoted by the same reference numerals.

  Further, for example, as shown in FIG. 4, a cylindrical portion 90 </ b> F constituting the hollow portion H <b> 3 may be integrally protruded from the rotating member 90 side. In this example, since the rotation member 90 is formed of a casting, the design is changed so that a member including the cylindrical portion 90F is formed with respect to the mold of the rotation member 90. The rotating member 90 including the cylindrical portion 90F can be manufactured without increasing costs and manufacturing man-hours. Further, since the cylindrical portion 90F is integrated with the rotating member 90 and only one O-ring 84 is required, the number of parts can be reduced.

  Further, for example, as shown in FIG. 5, a cylindrical portion 92F constituting the hollow portion H4 may be integrally projected from the second carrier 92 side. Also in this case, since the second carrier 92 is formed of a casting, the design cost is changed by changing the design so that a member including the cylindrical portion 92F is formed with respect to the mold of the second carrier 92. In addition, the second carrier 92 including the cylindrical portion 92F can be manufactured without increasing the number of manufacturing steps. Also in this example, a part of the inner peripheral portion 92F1 of the cylindrical portion 92F has the shape of the enlarged / expanded portion EP5 obtained by extending the expanded portion EP4 formed by the inner peripheral surface 92A of the second carrier 92. You can also. Furthermore, since the cylindrical portion 92F is integrated with the second carrier 92 and only one O-ring 82 is required, the number of parts can be reduced.

  The joint drive device 94 shown in FIG. 5 does not have a transmission internal gear (36). That is, the motive power of the motor 16 is transmitted to a pinion 26 formed on the motor shaft 24 and a gear 28 meshing with the pinion 26, and then directly through the spline 30, there are three eccentric body shafts 94A to 94C (94A , 94B only) is transmitted to one eccentric body shaft 94A. The external gears 66 and 68 are swung by the eccentric bodies 96A and 98A of the single eccentric body shaft 94A. The other two eccentric body shafts 94B and 94C are rotated by the swinging of the external gears 66 and 68 and function as driven eccentric body shafts. That is, as a result, the external gears 66 and 68 obtain driving force only from the eccentric body shaft 94A and swing while being supported by the three eccentric body shafts 94A to 94C.

  Due to the relative rotation generated between the external gears 66 and 68 and the internal gear 72, the external gears 66 and 68 rotate, and this rotation component is supplied to the first through the eccentric body shafts 94A to 94C. The speed reduction principle taken out from the second carriers (flange bodies) 46 and 92 is the same as that of the previous embodiment.

  In the present invention, the configuration of the speed reduction mechanism itself is not particularly limited. As in the example of FIG. 5, the structure in which the second carrier and the hollow member are integrated can be applied to the speed reduction mechanism having the transmission internal gears shown in FIGS. 1 to 4. Further, even a power transmission device of a speed reduction mechanism other than the listed configuration has a hollow portion that penetrates the entire device in the axial direction in the casing, and has an inner circumference at its axial end. The present invention can be applied to any power transmission device having a configuration in which the surface includes a hollow flange body that constitutes the end of the hollow portion, and a corresponding effect can be obtained.

  Further, in the present invention, as in the above-described embodiment, for example, even if the flange bodies are on both sides in the axial direction of the power transmission device, it is not always necessary to provide the widened portions on both flange bodies. You may just provide an expansion part only in the flange body of one side. When the flange body itself exists only on one side, it is naturally provided only on the flange body on the one side.

  Furthermore, as described above, the casing and the flange body may be fixed and any of them may be movable. However, in fact, in a so-called frame rotation type power transmission device in which the flange body side is fixed and the casing side rotates. The present invention is also applicable. Even in this case, since the motor as the drive source is always arranged on either side, if the power cable passes through the hollow portion (even if the flange body constituting the hollow portion does not move) However, when the motor itself rotates together with the casing, a twisted cable is rubbed against the inner peripheral surface of the hollow portion, and thus the present invention is applied to a power transmission device having such a frame rotating structure. Therefore, a corresponding effect can be obtained.

  Further, the application object of the present invention is not limited to the above example, and a hollow part through which an object other than a motor or a power supply cable, for example, an air hose for an air cylinder or a sensor wiring of various machines is passed. The present invention can also be applied to a power transmission device having

  For example, it can be applied as a power transmission device for industrial machines such as robots and machine tools.

DESCRIPTION OF SYMBOLS 12 ... Base member 14 ... Turning member 16 ... Motor 17 ... Cable 28 ... Gear 30 ... Spline 32 ... Transmission shaft 34 ... Transmission pinion 36 ... Transmission internal gear 36A ... Shaft part 44A-44C ... Eccentric body shaft 46, 48 ... First 1. Second carrier (flange body)
48A ... Inner peripheral surface EP1 ... Expanded portion 60A-60C, 62A-62C ... Eccentric body 85 ... Cylindrical pipe (hollow member)
H1 ... hollow part

Claims (6)

In the power transmission device having a hollow portion that penetrates the entire device in the axial direction,
The power transmission device has, at its axial end, a hollow flange body that constitutes either the fixing member or the output member of the power transmission device and whose inner peripheral surface constitutes the end of the hollow portion. And a widened portion having an inner diameter that increases toward the opening end is formed on the inner peripheral surface of the flange body. In claim 1,
The power transmission device, wherein a radial length is longer than an axial length of the expanding portion. In claim 1 or 2,
A power transmission device, wherein a hollow member constituting a part of the hollow portion is connected to a starting end of the expanded portion of the flange body. In claim 3,
The power transmission device, wherein an inner periphery of the hollow member is not expanded. In Claim 1 or 2, The hollow member which comprises a part of said hollow part is integrally extended with the said flange body, and a part of inner periphery of this hollow member extended the said expansion part, A power transmission device characterized by that. In any one of Claims 1-5,
The power transmission device, wherein the flange body is formed of a casting.

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