JP5385559B2 - Gear transmission with ring gear - Google Patents

Description

The present invention relates to a gear transmission comprising a-ring gear.

Patent Document 1 discloses a ring gear that is rotatably supported with respect to a hollow shaft. Patent Document 1 discloses a gear transmission provided with the ring gear. The ring gear (referred to as “transmission gear” in Patent Document 1) is located outside the hollow shaft (referred to as “cylindrical flange” in Patent Document 1), and between the ring gear and the hollow shaft. A rolling element is disposed as a bearing. Therefore, a gap for arranging the rolling elements is provided between the ring gear and the hollow shaft.
The gear transmission of Patent Document 1 employs a hollow shaft and a ring gear rotatably supported by the hollow shaft in order to pass the cable along the axis of the gear transmission. The torque of the motor is transmitted to the ring gear, and is transmitted from the ring gear to a gear fixed to a crankshaft (referred to as “eccentric shaft” in Patent Document 1).

JP 2007-278355 A

As described above, the gear transmission of Patent Document 1 employs a hollow shaft and a ring gear in order to pass a cable through the gear transmission. If the inner diameter of the hollow shaft is increased, that is, if the inner diameter of the ring gear is increased, the area through which the cable can pass can be increased. However, when the inner diameter of the ring gear is increased, the radial thickness of the ring gear is reduced and the strength of the ring gear is reduced. That is, in the conventional ring gear, the increase in the inner diameter (the inner diameter of the hollow shaft) and the strength of the ring gear are in a trade-off relationship.
The present specification discloses a ring gear that can increase the diameter of the through space inside the ring while maintaining strength.

The gear transmission disclosed in the present specification is an eccentric oscillating gear transmission in which either an internal gear or an external gear engaged with the internal gear rotates eccentrically with respect to the other. The gear transmission is arranged around the axis of the gear transmission, and includes a plurality of crankshafts that eccentrically rotate either one of the internal gear and the external gear, and the axis of the gear transmission. A hollow center shaft arranged coaxially, a ring gear arranged outside the center shaft and engaged with an input gear fixed to each crankshaft, and engaged with a ring gear And a relay gear that transmits the torque of the motor to the ring gear. The gear transmission disclosed in the present specification also has the following characteristics. A plurality of eccentric rotating gears are arranged at intervals in the axial direction of the gear transmission. A ring gear is disposed between the eccentric rotating gears. Two flanges are provided on the inner peripheral surface of the ring gear. A plurality of rolling elements for bearing are arranged between the two flanges. The ring gear is rotatably supported by the center shaft via the bearing rolling element. The thickness of the relay gear in the axial direction is smaller than the thickness of the ring gear in the axial direction. At least a part of the relay gear is engaged with the ring gear at the portion where the flange is provided.
In this specification, the following gear transmission is also disclosed. As a gear transmission is provided with an internal gear, one of the external gear engages with the internal gear is an eccentric oscillating-type gear transmission that eccentrically rotates relative to the other. The gear transmission is arranged around the axis of the gear transmission, and is arranged coaxially with a plurality of crankshafts that eccentrically rotate one of the internal gear and the external gear, and the axis of the gear transmission. And a ring gear disposed on the outside of the center shaft and engaged with an input gear fixed to each crankshaft. Further, two flanges are provided on the inner peripheral surface of the ring gear, and a plurality of rolling elements for bearing are arranged between the two flanges, and the ring gear is connected to the center shaft via the rolling elements for bearing. Is rotatably supported.
When the ring gear is rotatably supported on the shaft, a bearing is usually disposed between the gear and the shaft. Therefore, the diameter of the shaft that can be passed inside the ring gear is defined by the inner diameter of the bearing. In the prior art, in order to increase the inner diameter of the bearing, it was necessary to increase the inner diameter of the ring gear.
On the other hand, the bearing is composed of an inner race, an outer race, and rolling elements sandwiched between them. The inner race and the outer race are rings provided with grooves that make a round in the circumferential direction. The rolling element is restrained from moving in the axial direction of the shaft by the side wall of the groove of the inner race or the outer race.
In the technology disclosed in this specification, attention is paid to the groove structure of the bearing race (inner race or outer race). In the ring gear disclosed in the present specification, two flanges corresponding to the side walls of the groove of the bearing race are provided on the peripheral surface opposite to the surface on which the teeth are formed, and the rolling elements are disposed between the flanges. . Since the strength increases by providing two flanges, the radial thickness of the ring gear can be reduced. The rolling element abuts on the peripheral surface of the ring gear between the two flanges and abuts on the shaft. The peripheral surface of the ring gear sandwiched between the two flanges also functions as a bearing race. That is, the ring gear is rotatably supported by the shaft via the rolling elements. This ring gear does not require a bearing race to be arranged on the gear side, and can reduce the thickness of the ring gear. When the present invention is applied to a ring gear having outer teeth formed on the outer periphery, the diameter of the shaft passing through the inside of the ring gear can be increased. When the present invention is applied to an internal gear having internal teeth formed on the inner periphery, the inner diameter of the ring gear supported by the inner peripheral surface of the hollow shaft can be increased.

  In the ring gear disclosed in the present specification, teeth are formed on either the inner peripheral surface or the outer peripheral surface of the ring. Two flanges that make a round in the circumferential direction are provided on the other of the inner peripheral surface and the outer peripheral surface of the ring (the peripheral surface opposite to the peripheral surface on which the teeth are formed). A plurality of rolling elements for bearing are arranged between the two flanges. This ring gear is rotatably supported by the shaft via the bearing rolling element. The rolling elements for bearings may typically be “balls” or “rollers”.

The teeth provided on the peripheral surface of the ring gear are preferably formed over the entire axial width of the ring gear.
If the teeth are formed only in the range facing the thin portion (the portion where no flange is provided) of the ring gear, the torque transmitted to the ring gear is concentrated on the thin portion. That is, torque is concentrated and applied to the portion where the ring gear has low strength. If the teeth are formed over the entire axial width of the ring gear, the torque transmitted to the ring gear can be borne by the thick portion of the ring gear (the portion where the flange is provided).

As described above, a plurality of bearing rolling elements are disposed between the shaft and the ring gear. If the relative positions of the respective rolling elements for bearing are not restricted, the work of assembling the ring gear to the shaft becomes complicated. Therefore, the ring gear preferably includes a cage that holds the relative positions of the plurality of bearing rolling elements.
The cage preferably prevents the bearing rolling element from coming off between the two flanges. The ring gear can be assembled to the shaft in a state where the relative position between the ring gear and the rolling element for bearing is regulated in advance.

The present specification also discloses a gear transmission including the ring gear. In the gear transmission, either the internal gear or the external gear engaged with the internal gear rotates eccentrically with respect to the other. That is, the gear transmission disclosed in this specification is an eccentric oscillating gear transmission.
The gear transmission includes a plurality of crankshafts and a center shaft in addition to the ring gear described above. The crankshaft is disposed around the axis of the gear transmission, and eccentrically rotates either one of the internal gear and the external gear. The center shaft is disposed coaxially with the axis of the gear transmission. The “center shaft” corresponds to a “shaft” that rotatably supports the ring gear described above. The ring gear is rotatably supported by the center shaft via a bearing rolling element, and is engaged with an input gear fixed to each crankshaft. Further, “the axis of the gear transmission” in the present specification is the same as “the axis of the internal gear”.

  The gear transmission can secure a through space having a larger diameter than the conventional one inside the ring gear while maintaining strength. At the same time, a large torque can be transmitted from the ring gear to the crankshaft even though the ring gear is thin in the radial direction. In the case of a ring gear having external teeth, the diameter of the center shaft that penetrates the ring gear can be increased. In the case of a ring gear having internal teeth, the inner diameter of the ring gear can be increased without changing the center shaft that supports the ring gear outside the ring gear from the conventional center shaft.

  The gear transmission may include a plurality of external gears. In that case, it is preferable that the ring gear be disposed between the external gears. The external gear can prevent the ring gear from moving in the axial direction of the gear transmission.

  According to the technique of this specification, in the ring gear rotatably supported by the shaft, the diameter of the through space inside the ring can be increased while maintaining the strength of the ring gear.

Below, the characteristic of the ring gear of an Example is described.
(Feature 1) The two flanges and the gear circumferential surface between them correspond to the “groove” of the bearing race. Therefore, the ring gear of the embodiment can be expressed as follows. In the ring gear, external teeth are formed on the outer peripheral surface, and a groove that makes a round in the circumferential direction is formed on the inner peripheral surface. In the groove, a plurality of rolling elements for bearing are arranged, part of which extends from the groove to the inside in the radial direction of the ring gear. This ring gear is supported by the shaft via a rolling element for bearing.
The above expression can be expanded to a ring gear having inner teeth formed on the inner peripheral surface as follows. A ring gear that is rotatably supported with respect to the hollow shaft, and a groove that makes a round in the circumferential direction is formed on a surface facing the hollow shaft. In the groove, a plurality of rolling elements for a bearing that are partially protruding from the groove to the outside in the radial direction of the ring are arranged. This ring gear is supported by the shaft via a rolling element for bearing.
(Feature 2) The ring gear includes a cage that holds the rolling elements for bearing. The cage makes a circuit at a position facing the peripheral surface of the ring gear, and an opening for exposing the rolling element for bearing to the shaft side is formed.

(First embodiment)
In this embodiment, a gear transmission 100 including a ring gear 42 will be described.
FIG. 1 shows a cross-sectional view of the gear transmission 100. FIG. 2 is a sectional view taken along line II-II in FIG. FIG. 3 shows an enlarged view of a range surrounded by a broken line A in FIG. FIG. 4 is a sectional view taken along line IV-IV in FIG.
As shown in FIG. 1, a through-hole 5 is formed in the gear transmission 100 along the axis CL1. A cable 46 passes through the through hole 5. The through-hole 5 is formed by a through-hole formed in carriers 18 </ b> X and 18 </ b> Y, which will be described later, and an inner peripheral surface of a hollow shaft (center shaft) 6. The hollow shaft 6 is disposed coaxially with the axis CL1 of the gear transmission 100. The ring gear 42 is rotatably supported by the hollow shaft 6 via a roller (bearing rolling element) 44 (see also FIG. 2). As will be described later, torque of the motor 62 is transmitted to the ring gear 42, and torque is transmitted from the ring gear 42 to the crankshaft 14. Details of the gear transmission 100 will be described later.

The ring gear 42 will be described in detail.
As shown in FIG. 3, two flanges 68 are provided on the inner peripheral surface of the ring gear 42. The two flanges 68 are integrally formed at both ends of the ring gear 42 in the axial direction. Therefore, it can be said that the groove 70 is formed in the ring gear 42. A plurality of rollers 44 are disposed between the two flanges 68. As shown in FIGS. 3 and 4, the roller 44 is arranged so that a part thereof protrudes to the inner peripheral side from the flange 68. The roller 44 is in contact with the inner peripheral surface of the ring gear 42 and is in contact with the outer peripheral surface of the hollow shaft 6. The ring gear 42 is rotatably supported by the hollow shaft 6 by a plurality of rollers 44.
A gear 54 is engaged with the ring gear 42. The torque of the motor 62 (see FIG. 1) is transmitted to the ring gear 42 by the gear 54. As shown in FIG. 3, external teeth 76 are formed over the entire axial width of the outer peripheral surface of the ring gear 42. Torque transmitted from the gear 54 can be borne by the flange 68. Therefore, the strength of the ring gear 42 can be maintained even if the radial thickness of the ring gear 42 is reduced. When the radial thickness of the ring gear 42 is reduced, the inner diameter of the ring gear 42 can be increased, and as a result, the inner diameter of the hollow shaft 6 can be increased. If the inner diameter of the hollow shaft 6 can be increased, many wires and the like can be passed through the through hole 5 (see FIG. 1).

Here, with reference to FIG. 5 and FIG. 6, the ring gear 42 of the present embodiment and the conventional ring gear 142 will be compared.
FIG. 5 shows the positional relationship between the ring gear 42 and the hollow shaft 6 of this embodiment. FIG. 6 shows the positional relationship between the conventional ring gear 142 and the hollow shaft 106. The outer diameter R42 of the ring gear 42 and the outer diameter R142 of the ring gear 142 are equal.
As shown in FIG. 5, in the ring gear 42 of this embodiment, a roller 44 can be disposed between the flanges 68. In other words, the roller 44 can be disposed in the groove 70 of the ring gear 42. Therefore, the distance T42 from the outer peripheral surface of the ring gear 42 to the inner peripheral surface of the ring gear 42 can be made smaller than the distance T142 from the outer peripheral surface of the ring gear 142 to the inner peripheral surface of the ring gear 142. That is, the radial thickness T42 of the ring gear 42 can be made thinner than the radial thickness T142 of the ring gear 142. As a result, the ring gear 42 can increase the diameter of the substantial through space inside the ring more than the ring gear 142. As a result, the inner diameter R6 of the hollow shaft 6 can be made larger than the inner diameter R106 of the hollow shaft 106.

As described above, the torque applied to the ring gear 42 can be borne by the flange 68. Therefore, the strength of the ring gear 42 is maintained at the same level as the strength of the ring gear 142. The ring gear 42 has a diameter of the through space inside the ring larger than that of the conventional ring gear 142, and has the same strength as the ring gear 142.
The gear transmission 100 including the ring gear 42 can pass more wiring and the like through the gear transmission 100 along the axis CL1 than the conventional gear transmission.

Other features of the ring gear 42 will be described. Even if the ring gear 42 does not have the characteristics described below, the diameter of the through space inside the ring is larger than that of the conventional ring gear 142 and the ring gear 142 Similar strength can be obtained. That is, if two flanges 68 are provided on the inner peripheral surface of the ring gear 42, the diameter of the through space inside the ring is larger than that of the ring gear 142, and the same strength as the ring gear 142 can be obtained. .
As shown in FIGS. 3 and 4, the plurality of rollers 44 are positioned in the groove 70 of the ring gear 42 (between the two flanges 68) by the retainer 72. Therefore, the ring gear 42 can be assembled to the hollow shaft 6 with the roller 44 positioned in the groove 70 in advance. Assembling of the ring gear 42 and the hollow shaft 6 can be facilitated. The retainer 72 is a plate having an opening 72 a and makes a round around the inner periphery of the ring gear 42. As shown in FIG. 4, the width W <b> 72 of the opening 72 a is smaller than the diameter of the roller 44. As shown in FIG. 3, the retainer 72 is located on the opposite side of the position where the roller 44 and the ring gear 42 are in contact, with the axis 44 </ b> M of the roller 44 interposed therebetween. With such a structure, the retainer 72 can prevent the roller 44 from coming off between the flanges 68. The cage 72 can be formed of a material such as metal or resin.

The gear transmission 100 will be described.
As shown in FIGS. 1 and 2, the gear transmission 100 includes a case 34 in which a plurality of internal teeth pins 32 are arranged on the inner periphery, and two external gears 28 </ b> X arranged inside the case 34. 28Y is provided. In FIG. 2, an external gear 28Y appears. A plurality of internal teeth pins 32 are arranged around the inner periphery of the case 34 and form an internal gear together with the case 34. In the following description, the internal tooth pin 32 and the case 34 are collectively referred to as an internal gear 36.
As shown in FIG. 1, a through hole 28a is formed in the external gears 28X and 28Y. Eccentric bodies 12X and 12Y fixed to the crankshaft 14 are fitted into the through holes 28a via the needle roller bearings 8, respectively. When the crankshaft 14 rotates, the external gears 28X and 28Y rotate eccentrically with respect to the internal gear 36. An input gear 38 is also fixed to the crankshaft 14. The input gear 38 meshes with the ring gear 42.
As shown in FIG. 2, the ring gear 42 is disposed coaxially with the axis CL <b> 1 and meshes with three input gears 38 and a gear 54 fixed to the relay shaft 2 (see FIG. 1).

  As shown in FIG. 1, the relay shaft 2 is supported on the carriers 18 </ b> X and 18 </ b> Y by a pair of deep groove ball bearings 52. A gear 4 is fixed to the end of the relay shaft 2. The gear 4 meshes with a motor gear 56 fixed to the output shaft 58 of the motor 62. The torque of the output shaft 58 of the motor 62 is transmitted to the three crankshafts 14 through the motor gear 56, the gear 4, the gear 54, the ring gear 42 and the input gear 38.

The crankshaft 14 is supported by the carriers 18X and 18Y by a pair of tapered roller bearings 16. The carrier 18Y is fixed to the pedestal 48. Since the crankshaft 14 passes through the through holes 28a of the external gears 28X and 28Y, the carriers 18X and 18Y and the external gears 28X and 28Y do not rotate relatively. The carrier 18X and the carrier 18Y are connected by a columnar portion 18Z shown in FIG. The columnar portion 18Z passes through the through hole 28b of the external gear 28Y. A gap that allows eccentric rotation of the external gear 28Y is provided between the columnar portion 18Z and the through hole 28b.
Although illustration is omitted, a through hole is also formed in the external gear 28X, and the columnar portion 18Z passes through the through hole.

An internal gear 36 (case 34) is supported on the carriers 18X and 18Y by a pair of angular ball bearings 26. The internal gear 36 can rotate relative to the carriers 18X and 18Y.
As shown in FIG. 2, the external gear 28 </ b> Y meshes with the internal gear 36. The number of external teeth of the external gear 28Y is different from the number of internal teeth of the internal gear 36 (the number of internal pins 32). When the external gear 28Y rotates eccentrically, the internal gear 36 rotates. That is, when the external gear 28Y rotates eccentrically, the internal gear 36 rotates with respect to the carriers 18X and 18Y.
The rotated member 22 is fixed to the internal gear 36. As described above, since the carrier 18 </ b> Y is fixed to the pedestal 48, the gear transmission 100 can rotate the rotated member 22 relative to the pedestal 48.

Other features of the gear transmission 100 will be described.
As shown in FIG. 1, the ring gear 42 is disposed between the external gear 28X and the external gear 28Y. Therefore, it is possible to suppress the ring gear 42 from moving in the direction of the axis line CL1. A bearing that restricts movement of the ring gear 42 in the direction of the axis CL1 can be omitted.
An input gear 38 is fixed to the crankshaft 14 between the pair of tapered roller bearings 16. Therefore, the torque of the ring gear 42 is transmitted to the crankshaft 14 at a position where the displacement of the crankshaft 14 is restricted. The rotation balance of the crankshaft 14 is stabilized. Similarly, a gear 54 is fixed to the relay shaft 2 between the pair of deep groove ball bearings 52. Since the rotation balance of the gear 54 is stabilized, a stable torque can be transmitted from the gear 54 to the ring gear 42.
An oil seal 24 is disposed between the carriers 18X and 18Y and the case 34, an oil seal 55 is disposed between the carrier 18X and the relay shaft 2, and an O-ring is provided between the carriers 18X and 18Y and the hollow shaft 6. 71 (see FIG. 3) is arranged. The oil seals 24 and 55 and the O-ring 71 can prevent oil in the gear transmission 100 from leaking out of the gear transmission 100.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

  In the above embodiment, the gear transmission 100 including the ring gear 42 has been described. The ring gear 42 can also be used for devices other than the gear transmission. In the embodiment, the ring gear 42 is supported outside the hollow shaft 6. In this case, the shaft that supports the ring gear 42 may be solid.

  It is also possible to support a ring gear having internal teeth inside the hollow shaft. That is, it may be a ring gear in which inner teeth are formed on the inner peripheral surface of the ring and two flanges are provided on the outer peripheral surface of the ring. In this case, a plurality of rolling elements for bearing are arranged between the two flanges, and the ring gear is rotatably supported on the hollow shaft via the rolling elements for bearing.

  A plurality of internal gears may rotate eccentrically with respect to the external gear. In that case, it is preferable to arrange | position a ring gearwheel between internal gears. A bearing for restricting the movement of the ring gear in the axial direction can be omitted.

  The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

Sectional drawing of the gear transmission of 1st Example is shown. Sectional drawing along the II-II line | wire of FIG. 1 is shown. The enlarged view of the range enclosed with the broken line A of FIG. 1 is shown. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. The figure explaining the positional relationship of the ring gear of a 1st Example and a hollow shaft is shown. The figure explaining the positional relationship of the conventional ring gearwheel and a hollow shaft is shown.

Explanation of symbols

6: Shaft (center shaft)
14: crankshaft 28: external gear 36: internal gear 38: input gear 42: ring gear 44: rolling element 68 for bearing: flange 72: cage 76: external gear 100: gear transmission

Claims (5)

An eccentric oscillating gear transmission in which either one of the internal gear and the external gear engaged with the internal gear rotates eccentrically with respect to the other,
A plurality of crankshafts arranged around the axis of the gear transmission and eccentrically rotating either one of the internal gear and the external gear;
A hollow center shaft arranged coaxially with the axis of the gear transmission,
A ring gear disposed on the outside of the center shaft and engaged with an input gear fixed to each crankshaft;
A relay gear that is engaged with the ring gear and transmits the torque of the motor to the ring gear ;
A plurality of eccentric rotating gears are arranged at intervals in the axial direction of the gear transmission,
A ring gear is arranged between the eccentric rotating gears,
Two flanges are provided on the inner peripheral surface of the ring gear,
A plurality of rolling elements for bearing are arranged between two flanges,
Via the rolling element bearing, the ring gear is rotatably supported on the center shaft,
The axial thickness of the relay gear is thinner than the axial thickness of the ring gear,
A gear transmission , wherein at least a part of the relay gear is engaged with a ring gear at a portion where the flange is provided .   The gear transmission according to claim 1, wherein the teeth of the ring gear are formed over the entire width in the axial direction of the ring gear.   The gear transmission according to claim 1, further comprising a cage that holds the relative positions of the plurality of bearing rolling elements.   4. The gear transmission according to claim 3, wherein the retainer prevents the rolling element for a bearing from coming off between two flanges. 5. The eccentric rotating gear is an external gear ;
In the axial direction of the gear transmission, the thickness of the external gear is thinner at the portion where the ring gear is disposed than the outer peripheral portion engaged with the internal gear ,
The gear transmission according to any one of claims 1 to 4, wherein an interval between the external gears is narrower in an outer peripheral portion engaging with the internal gear than in a portion where the ring gear is disposed .

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