JP5064272B2 - Grease leakage prevention structure for unit gear unit - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a grease leakage prevention structure for a unit-type gear device, and more specifically, is used in a robot, a machine tool, a liquid crystal / semiconductor manufacturing apparatus, etc. that require high positioning accuracy, smooth rotation and quietness. The present invention relates to a grease leakage prevention structure for a unit-type gear device provided with a rocking gear device having high accuracy and a high reduction ratio.

  2. Description of the Related Art Conventionally, a wave gear reducer is known as a gear reducer that is lightweight, compact, and capable of obtaining high accuracy and a high reduction ratio without using a complicated mechanism or structure. A typical wave gear reducer includes an annular rigid internal gear, a cup-shaped flexible external gear disposed on the inside thereof, and the flexible external gear flexed into an ellipse to form a rigid internal gear. And a wave generator having an elliptical profile that meshes with the tooth gear and moves the meshing position of both gears in the circumferential direction. When the meshing position moves in the circumferential direction, relative rotation occurs between the two gears due to the difference in the number of teeth of the two gears. Generally, the wave generator is rotated at a high speed by a high-speed rotation source such as a motor, and the rigid internal gear side is fixed, so that a rotational output that is greatly decelerated can be obtained from the flexible external gear side (patent) Reference 1).

  However, the conventional typical wave gear reducer has a problem that a commercially available bearing cannot be used because the wave generator uses a special bearing whose inner ring is elliptical and whose outer ring is elastically deformable. In addition, since the outer ring of the bearing is thin, when the overload is applied, the rigid inner gear and the flexible external gear are caused by the bending of the outer ring that occurs between the balls of the bearing. There is a possibility that a ratcheting phenomenon occurs in which the meshing momentarily shifts. Further, since the length of the long axis of the cam portion of the wave generator on the high speed rotation side has a large ratio to the inner diameter of the rigid internal gear, the moment of inertia tends to increase.

  Therefore, the present inventor used the conventional wave gear reducer as a gear reducer that can obtain the same high accuracy and high reduction ratio while solving the problems of the conventional typical wave gear reducer. Instead of an elliptical contour wave generator, two circular contour eccentric rollers are provided, and the centers of the circular contours of the eccentric rollers are positioned apart from the rotation axis by the predetermined amount. Using a swing generator with an overlapping arrangement, the flexible external gear is bent and meshed with the rigid internal gear, and the meshing position of both gears is moved in the circumferential direction to greatly reduce the speed. We developed a rocking gear device that obtains the rotational output. Then, as shown in FIGS. 4 and 5, a unit-type gear device 100 including this oscillating gear device 110 is under development.

In this oscillating gear device 110, the meshed portion of the rigid internal gear 120 and the flexible external gear 130, the inside of the flexible external gear 130, and the outer peripheral surface of the eccentric roller 141 of the oscillation generator 140 are contacted. It is necessary to efficiently lubricate the part. Further, in a unit type gear device provided with such a gear reducer, a method using an oil seal is generally used as a method for preventing leakage of grease used for lubrication. Specifically, as shown in FIGS. 4 and 5, in the unit-type gear device 100 including the oscillating gear device 110 being developed by the present inventor, the outside of the input-side bearing 162 that supports the input shaft 161 ( By providing the oil seal 163 in contact with the input shaft 161 at the position in FIG. 4) or the inside (FIG. 5), grease leakage from the swing gear device 110 to the opening side of the input unit 300 can be prevented. .
JP-A-10-110790

  However, the unit type gear device 100 shown in FIGS. 4 and 5 is provided with the oil seal 163 so as to come into contact with the input shaft 161 at a position outside or inside the input side bearing 162 that supports the input shaft 161. Therefore, there is a problem that the rotational efficiency of the input shaft 161 is lowered due to the sliding resistance. Moreover, since the space which provides the oil seal 163 is required, there exists a problem that the full length of the input unit 300 becomes large. Moreover, since the unit type gear apparatus 100 is provided with the oil seal 153 also in the position which contacts the output shaft 151, the inside of the unit type gear apparatus 100 in which the rocking gear apparatus 110 is arranged becomes a sealed space. Since heat is generated by the high speed rotation of the swing generator 140 in this sealed space, the inside of the unit type gear device 100 becomes high pressure, and the oil seal 163 is input due to the internal and external pressure difference of the unit type gear device 100. There is a problem that grease leaks from the contact portion of the shaft 161.

  Accordingly, the present invention provides a unit-type gear device having a swing gear device, in which grease leakage from the swing gear device to the opening side of the input unit can be achieved without providing an oil seal in contact with the input shaft in the input unit. It is an object of the present invention to provide a grease leakage prevention structure for a unit-type gear device that can prevent the above-described problem.

In order to solve the above problems, the grease leakage prevention structure of the unit type gear device of the present invention is a grease leakage prevention structure of a unit type gear device provided with a swing gear device,
The oscillating gear device includes an annular rigid internal gear, an annular flexible external gear arranged inside the rigid internal gear, and a rocker fitted inside the flexible external gear. A rotation generator, and the flexible external gear is bent, and the two gears are partially meshed at two locations facing each other across the center of the rigid internal gear, and the rotation generator is rotated. By causing the meshing position of both gears to move in the circumferential direction, a relative rotation is generated between the rigid internal gear and the flexible external gear,
The swing generator is disposed on an outer periphery of the eccentric cam, a circular contour eccentric cam that rotates eccentrically around a rotation axis of the swing generator, a bearing fitted on the outer periphery of the eccentric cam, and Two eccentric rollers each having a circular contour provided with a wheel, and the two eccentric rollers are overlapped so that the centers of the circular contours of the eccentric rollers are positioned away from the rotation shaft by the predetermined amount in the opposite directions. Arranged,
The unit-type gear device includes the rigid internal gear, the flexible external gear, an output shaft connected and fixed to the flexible external gear, and an output unit having an output unit housing that supports them. The swing generator, the input shaft to which the swing generator is connected and fixed, the input side bearing fixed to the input shaft, and the input unit having an input unit housing that supports the input shaft. And
The input unit has an output unit side end face facing the eccentric roller on the output unit side,
The output unit side end surface has a grease reservoir groove recessed in the opposite direction to the output unit side,
The grease reservoir groove is formed on the rotating shaft side of the swing generator and on the outer side of the input side bearing from the meshing position of the rigid internal gear and the flexible external gear. .

  According to the above configuration, the output unit side end surface of the input unit is annularly provided around the rotation shaft on the rotation shaft side of the oscillation generator from the meshing position of the rigid internal gear and the flexible external gear. The grease used for lubrication of the meshing portion of the rigid internal gear and the flexible external gear is blown outward by the rotation of the oscillation generator. This grease can be stored in the grease storage groove when it adheres to the output unit side end surface and moves to the rotation shaft side, and it is possible to efficiently prevent the grease from entering the rotation shaft side of the grease storage groove. Can do. Therefore, it is possible to prevent grease leakage from the oscillating gear device to the opening side of the input unit without providing an oil seal in contact with the input shaft in the input unit. As a result, the unit-type gear device having the above configuration does not need to provide the input unit with an oil seal that comes into contact with the input shaft. . Further, since a space for providing an oil seal is not necessary, the entire length of the input unit can be reduced accordingly. Furthermore, since the internal pressure of the unit type gear device can be released to the outside, the internal / external pressure difference of the unit type gear device is reduced, and the grease leakage due to the internal / external pressure difference can be eliminated.

  Furthermore, the output unit side end surface of the input unit has a grease leakage prevention wall provided in an annular shape around the rotation shaft on the rotation shaft side of the oscillation generator from the grease reservoir groove. .

  According to the above configuration, the end face on the output unit side of the input unit has the grease leakage prevention wall provided around the rotation shaft on the rotation shaft side of the oscillation generator from the grease storage groove. It is possible to prevent the grease that is about to move to the rotating shaft side from being blocked by the grease leakage prevention wall and further entering the rotating shaft side.

  It is preferable that the highest portion of the grease leakage prevention wall is close to the eccentric roller.

  According to the above configuration, when the grease that has moved from the grease reservoir groove to the rotary shaft side penetrates to a position that exceeds the grease leakage prevention wall, the highest part of the grease leakage prevention wall is close to the eccentric roller. Grease contacts the end face of the eccentric roller at the highest part of the grease leakage prevention wall. Since the eccentric roller rotates at high speed, the grease that has contacted moves the end surface of the eccentric roller to the outside by centrifugal force. Therefore, it is possible to prevent the grease from entering the rotating shaft further than the grease leakage prevention wall.

  According to the present invention, in a unit-type gear device having a swing gear device, grease leakage from the swing gear device to the opening side of the input unit can be achieved without providing an oil seal in contact with the input shaft in the input unit. It is possible to provide a grease leakage prevention structure for a unit-type gear device that can prevent the above.

  Hereinafter, with reference to the drawings, a unit type gear device to which a grease leakage preventing structure for a unit type gear device according to an embodiment of the present invention is applied will be described.

  FIG. 1 is a cross-sectional view of a unit gear device to which the present invention is applied, in a plane including a device axis. The unit-type gear device 1 includes an output unit 2 and an input unit 3. The oscillating gear device 10 is incorporated in the end of the output unit 2 on the input unit 3 side.

  The oscillating gear device 10 includes an annular rigid internal gear 20, an annular flexible external gear 30 that can be elastically deformed, and an oscillation generator 40. The rigid internal gear 20 includes an internal tooth portion 21 formed on the inner peripheral surface. The flexible external gear 30 has a cup shape and includes an external tooth portion 31 formed on the outer peripheral surface of the opening of the cup. The swing generator 40 includes two eccentric rollers 41.

  In the oscillating gear device 10, a flexible external gear 30 is arranged inside a rigid internal gear 20, and a oscillating generator 40 is fitted inside the flexible external gear 30, so that a flexible external tooth is provided. By bending the gear 30, the internal teeth formed in the internal tooth portion 21 of the rigid internal gear 20 and the external teeth formed in the external tooth portion 31 of the flexible external gear 30 are rigid internal teeth. The gear 20 is configured so as to mesh at two locations facing each other across the center of the gear 20.

  The swing generator 40 includes two eccentric rollers 41 having a circular contour that rotate about the rotation axis of the swing generator 40. The eccentric roller 41 includes a circular contour eccentric cam 42 that rotates eccentrically by a predetermined amount, a bearing 43 fitted on the outer periphery of the eccentric cam 42, and a wheel 44 disposed on the outer periphery of the bearing 43. The eccentric cam 42 is fixed to the input shaft 61 so as to rotate about the rotation axis of the swing generator 40. The axis of the rotation shaft of the swing generator 40 coincides with the axis of the input shaft 61, that is, coincides with the device axis 1a. The type of the bearing 43 of the eccentric roller 41 is not particularly limited, and an open type, a contact seal type, a non-contact seal type, a shield type, and the like can be suitably used. Among these, a non-contact shielded bearing on both sides is preferable because grease can be enclosed in the bearing.

  Here, the arrangement state of the two eccentric rollers 41 of the swing generator 40 will be described with reference to FIG. FIG. 2 is an explanatory view schematically showing an arrangement state of two eccentric rollers of the swing generator. As shown in FIG. 2, the two eccentric rollers 41 of the swing generator 40 are configured so that the center 41a of the circular contour of each eccentric roller 41 is opposite to the rotation axis of the swing generator 40, that is, the device axis 1a. They are arranged so as to be separated by a predetermined amount (ε). Since the swing generator 40 has such a shape, when the swing generator 40 is fitted inside the flexible external gear 30, the outer peripheral surface of the eccentric roller 41 becomes the flexible external gear. 30, the flexible external gear 30 bends in contact with the inner peripheral surface of the external tooth portion 31, and the external teeth of the flexible external gear 30 are the internal teeth of the rigid internal gear 20 and the rigid internal gear 20. Can be engaged with each other at two opposite locations.

  Thus, the oscillating gear device 10 incorporated in the unit type gear device 1 is different from the wave generator provided with the bearing having the elliptical cam and the elastically deformable outer ring in the conventional wave gear reducer, Two eccentric rollers 41 having a circular contour are provided, and the center 41a of the circular contour of each eccentric roller 41 is positioned away from the rotation axis (device axis 1a) of the swing generator 40 by the predetermined amount in the opposite directions. In addition, a swing generator 40 having a configuration of being stacked is provided. Therefore, in this oscillating gear device 10, the eccentric cam 42 used for the eccentric roller 41 has a circular contour, and it is not necessary to use a special bearing having an elliptical inner ring and an elastically deformable outer ring. A commercially available bearing can be used for the bearing 43 fitted to the outer periphery of the cam 42. Further, since it is not necessary to use a bearing having a thin outer ring that can be elastically deformed on the back surface of the external teeth of the flexible external gear 30, by providing a wheel 44 outside the bearing 43, a thin wall that can be elastically deformed is provided. Occurrence of the ratcheting phenomenon due to the bending of the outer ring can be suppressed. Furthermore, since the ratio of the diameter of the eccentric cam 42 to the diameter of the rigid internal gear 20 is small, the moment of inertia on the high-speed rotation side can be reduced.

  Next, operation | movement of the rocking gear apparatus 10 is demonstrated using FIG. FIG. 3 is an explanatory diagram of the operation of the oscillating gear device.

  As shown in FIG. 3, before the rotation, the internal teeth shown by the oblique lines of the rigid internal gear 20 and the external teeth shown by the black of the flexible external gear 30 mesh with each other. When the input shaft 61 is driven by a motor or the like, the swing generator 40 starts to rotate. When the swing generator 40 rotates 90 degrees, the meshing position moves 90 degrees in the circumferential direction. In this oscillating gear device 10, since the difference between the number of teeth of the internal teeth of the rigid internal gear 20 and the number of teeth of the flexible external gear 30 is two, the oscillating generator 40 has a meshing position around the circumference. In order for the meshing position to return to the internal teeth indicated by the diagonal lines of the rigid internal gear 20, the flexible external gear 30 rotates by the number of external teeth plus two. There must be. That is, when the swing generator 40 rotates 360 degrees, the external teeth adjacent to the external teeth shown in black are meshed with the internal teeth shown in diagonal lines. As a result, the flexible external gear 30 rotates relative to the rotation direction of the oscillation generator 40 by the number of teeth of two sheets. Since the unit type gear device 1 of the present embodiment is fixed to the output unit housing 50 so that the rigid internal gear 20 does not relatively rotate, the number of teeth of the internal teeth and external teeth from the flexible external gear 30. The rotation that is greatly decelerated according to the difference can be output to the output shaft 51.

  The unit gear device 1 can be separated into an output unit 2 and an input unit 3. The output side unit 2 in the separated state includes a rigid internal gear 20, a flexible external gear 30, and an output shaft 51. The rigid internal gear 20 is fixed to the output unit housing 50 and the bearing holder 54 with a rigid internal gear fixing bolt 23. An output shaft 51 is connected and fixed to the bottom surface of the flexible external gear 30 in a coaxial state. The flexible external gear 30 and the output shaft 51 are provided in the bolt hole of the thick output shaft mounting portion 32 provided on the bottom surface portion of the cup-shaped flexible external gear 30. The flexible external gear mounting bolts 34 are fitted and fixed with the presser plate 35 interposed therebetween. The output shaft 51 is supported by an output side bearing 52, and the output side bearing 52 is held by a bearing holder 54 and a bearing pressing plate 55. As the output side bearing 52, a cross roller bearing is usually used. Further, an output side oil seal 53 is provided next to the output side bearing 52.

  On the other hand, the input unit 3 in the separated state includes a swing generator 40 and an input shaft 61, and the swing generator 40 is fixed coaxially to the tip of the input shaft 61. The input shaft 61 is supported by an input side bearing 62, and the input side bearing 62 is held by an input unit housing 60. As the input side bearing 62, a non-contact shield type bearing on both sides is usually used. Inside the outer peripheral portion of the output unit 2 side end surface of the input unit housing 60, a guide portion having a shape that can be fitted to the outer periphery of the input unit 3 side end portion of the output unit 2, that is, the outer periphery of the rigid internal gear 20. 60d is provided. By providing such a guide portion 60d, it is possible to fit the output unit 2 and the input unit 3 smoothly and easily while guiding the outer periphery of the input side end portion of the output unit 2.

  The unit-type gear device 1 is assembled by fitting the output-side unit 2 and the input-side unit 3 and connecting and fixing the input unit housing 60 and the rigid internal gear 20 with the unit connecting bolt 64. In the unit-type gear device 1, the output unit 2 and the input unit 3 are fitted so that the axis of the output shaft 51 and the axis of the input shaft 61 coincide. Therefore, in the assembled gear device 1, the axis of the output shaft 51 and the axis of the input shaft 61 coincide in the assembled state, and this coincides with the device axis 1a (see FIG. 1).

  Next, the grease leakage prevention structure of this embodiment will be described. As shown in FIG. 1, an annular grease retaining groove 60 a and an annular grease leakage prevention wall 60 b are provided around the input shaft 61 on the output unit 2 side end surface of the input unit housing 60. The grease reservoir groove 60a is provided on the input shaft 61 side from the meshing position of the rigid internal gear 20 and the flexible external gear 30, and the grease leakage prevention wall 60b is on the input shaft 61 side from the grease reservoir groove 60a. Is provided. In the unit type gear device 1, the grease reservoir groove 60a and the grease leakage prevention wall 60b are provided concentrically with the input shaft 61, but the present invention is not limited to this.

  When the input shaft 61 is driven by a motor or the like and the swing generator 40 starts to rotate at a high speed, the meshing portion between the rigid internal gear 20 and the flexible external gear 30 and the inside of the flexible external gear 30 The lubricating grease at the contact portion of the outer peripheral surface of the eccentric roller 41 is scattered outward by centrifugal force. The scattered grease accumulates in a gap 60c formed between the side surface of the rigid internal gear 20 of the oscillating gear device 10 and the output unit 2 side end surface of the input unit housing 60, and is circulated and used for lubrication of the meshing portion and the like. The

  Since the grease overflowing from the gap 60c is collected in the grease reservoir groove 60a formed on the output unit 2 side end surface of the input unit housing 60, the grease is prevented from entering the input shaft 61 side from the grease reservoir groove 60a. can do. Even if the grease moves from the grease reservoir groove 60a to the input shaft 61 side, it can be blocked by the grease leakage prevention wall 60b and prevented from entering the input shaft 61 side beyond the grease leakage prevention wall 60b. . Even if the grease that has moved from the grease reservoir groove 60a to the input shaft 61 side enters the position where it is about to exceed the grease leakage prevention wall 60b, the highest portion of the grease leakage prevention wall 60b is close to the eccentric roller. The grease that has reached the highest portion of the grease leakage prevention wall 60 b comes into contact with the end surface of the eccentric roller 41. Since the eccentric roller rotates at a high speed, the grease contacted is blown outward by centrifugal force. Therefore, it is possible to prevent the grease from entering the input shaft 61 side from the grease leakage prevention wall 60b. Since the unit-type gear device 1 has such a grease leakage prevention structure, it is possible to reliably input from the oscillating gear device 10 without providing a conventional oil seal (see FIGS. 4 and 5). Grease leakage to the opening side of the unit 3 can be prevented.

  Since the unit type gear device 1 does not need to provide an oil seal in contact with the input shaft 61 in the input unit 3, the problem that the rotational efficiency of the input shaft 61 is reduced due to the sliding resistance of the oil seal can be solved. Further, since the space for providing the oil seal is not necessary, the entire length of the input unit 3 can be reduced. Furthermore, since the internal pressure of the unit type gear device 1 can be released to the outside, the internal / external pressure difference of the unit type gear device 1 is reduced, and the grease leakage due to the internal / external pressure difference can be eliminated.

  The depth and the width of the grease reservoir groove 60a are not particularly limited as long as the grease reservoir groove 60a has a depth and a width capable of storing the grease. Since the amount of grease that can be stored increases, it is preferable that the grease is deeper within the allowable range of the structure, and that the width is wider. Further, the height and width of the grease leakage prevention wall 60b are not limited as long as the height and width can prevent the grease from entering the input shaft side 61. However, the position is intended to exceed the grease leakage prevention wall 60b. It is preferable that the highest part is close to the eccentric roller 41 so that the grease reaching the highest part of the grease leakage prevention wall 60b can contact the end surface of the eccentric roller 41.

  In the unit type gear device 1, the grease reservoir groove 60a and the grease leakage prevention wall 60b are formed separately, but may be formed integrally. That is, the highest portion of the wall may be formed close to the eccentric roller 41 so that the wall of the grease reservoir groove 60a on the input shaft 61 side becomes the grease leakage prevention wall 60b.

  The embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made within the scope shown in the claims.

It is sectional drawing in the plane containing the apparatus axis line of the unit type gear apparatus to which invention is applied. It is explanatory drawing which shows typically the arrangement | positioning state of two eccentric rollers of a rocking | fluctuation generator. It is explanatory drawing of operation | movement of a rocking gear apparatus. It is sectional drawing in the plane containing the apparatus axis line of the conventional unit type gear apparatus which provided the oil seal in the input unit. It is sectional drawing in the plane containing the apparatus axis line of the conventional unit type gear apparatus which provided the oil seal in the input unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Unit type gear apparatus 1a Apparatus axis line 2 Output unit 3 Input unit 10 Oscillating gear apparatus 20 Rigid internal gear 21 Internal tooth part 30 Flexible external gear 31 External tooth part 32 Output shaft attaching part 34 Flexible external tooth Gear mounting bolt 35 Flexible external gear presser plate 40 Oscillating generator 41 Eccentric roller 42 Eccentric cam 43 Bearing 44 Wheel 50 Output unit housing 51 Output shaft 52 Output side bearing 53 Output side oil seal 60 Input unit housing 60a Grease Reservoir groove 60b Grease leakage prevention wall 61 Input shaft 62 Input side bearing

Claims (3)

A grease leakage prevention structure for a unit-type gear device provided with a rocking gear device,
The oscillating gear device includes an annular rigid internal gear, an annular flexible external gear arranged inside the rigid internal gear, and a rocker fitted inside the flexible external gear. A rotation generator, and the flexible external gear is bent, and the two gears are partially meshed at two locations facing each other across the center of the rigid internal gear, and the rotation generator is rotated. By causing the meshing position of both gears to move in the circumferential direction, a relative rotation is generated between the rigid internal gear and the flexible external gear,
The swing generator is disposed on an outer periphery of the eccentric cam, a circular contour eccentric cam that rotates eccentrically around a rotation axis of the swing generator, a bearing fitted on the outer periphery of the eccentric cam, and Two eccentric rollers each having a circular contour provided with a wheel, and the two eccentric rollers are overlapped so that the centers of the circular contours of the eccentric rollers are positioned away from the rotation shaft by the predetermined amount in the opposite directions. Arranged,
The unit-type gear device includes the rigid internal gear, the flexible external gear, an output shaft connected and fixed to the flexible external gear, and an output unit having an output unit housing that supports them. The swing generator, the input shaft to which the swing generator is connected and fixed, the input side bearing fixed to the input shaft, and the input unit having an input unit housing that supports the input shaft. And
The input unit has an output unit side end face facing the eccentric roller on the output unit side,
The output unit side end surface has a grease reservoir groove recessed in the opposite direction to the output unit side,
The grease reservoir groove is formed on the rotary shaft side of the oscillation generator and on the outer side of the input side bearing from the meshing position of the rigid internal gear and the flexible external gear. Grease leakage prevention structure for unit type gear unit.   The end face on the output unit side of the input unit has a grease leakage prevention wall provided annularly around the rotation shaft on the rotation shaft side of the oscillation generator from the grease reservoir groove. 2. A grease leakage prevention structure for a unit type gear device according to 1.   The grease leakage prevention structure for a unit-type gear device according to claim 2, wherein the highest portion of the grease leakage prevention wall is close to the eccentric roller.

Images