Gear mechanisms, reducers

Abstract

To decrease size when viewed along an axis direction.SOLUTION: A gear mechanism includes a first shaft, a second shaft 21a forming an angle with the first shaft, a first gear group that has a plurality of first gears 11b and 11c transmitting rotations of the first shaft to the second shaft, and a second gear group that has a plurality of second gears transmitting rotations of the second shaft transmitted from the first shaft side to an output side 30, and in which a straight line L1 connecting a rotation center of the initial second gear 21 located on the most second shaft side among the plurality of second gears and a rotation center of the last second gear 22 located on the most output side intersects the first shaft when viewed in a direction along the second shaft.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a gear mechanism and a reducer. [Background technology]

[0002] BACKGROUND ART In industrial robots, machine tools, and the like, reducers are used to reduce the rotation speed of a rotary drive source such as a motor (see, for example, Patent Document 1). A gear mechanism may be interposed between the input gear of the reducer described in Patent Document 1 and the output gear of the motor so as to mesh with the input gear to transmit driving force.

[0003] When a reducer incorporating such a gear mechanism is used to drive a turntable or the like, it is desirable to arrange the reducer so that its thickness in the vertical direction, i.e., along the axis of the reducer, is small and flat. For this reason, a gear mechanism is known in which the axis of the reducer is arranged so that the axis of the motor intersects with the axis of the reducer.

[0004] In this case, when viewed in a direction along the axis of the reducer, the gear train of the gear mechanism and the motor shaft are arranged in series on the outside in the radial direction, with the axis of the reducer as the center. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5231530 Summary of the Invention [Problem to be solved by the invention]

[0006] In a turntable or the like, it is preferable that both the reducer and the rotary drive source such as the motor are covered by the turntable. In other words, it is preferable that the motor is positioned so that the outermost periphery of its outline is smaller than the outer diameter of the table when viewed from the center of the turntable along the axial direction. However, if the dimensions of the reducer and motor are larger than the outer diameter of the table, the motor may protrude from the table's mounting surface, hindering the turntable's miniaturization. As a result, further miniaturization of the table is limited by the size of the reducer and motor required to achieve a certain output.

[0007] The present invention aims to achieve an object of providing a gear mechanism and a reducer that can be made flat and have a small area as viewed along the axial direction. [Means for solving the problem]

[0008] A gear mechanism according to one embodiment of the present invention comprises a first axis, a second axis that forms an angle with the first axis, a first gear group having a plurality of first gears that transmit the rotation of the first axis to the second axis, and a second gear group having a plurality of second gears that transmit the rotation of the second axis transmitted from the first axis side to an output side, wherein a straight line connecting a rotation center of a first second gear that is located closest to the second axis among the plurality of second gears and a rotation center of a last second gear that is located closest to the output side forms an angle with the first axis when viewed in a direction along the second axis.

[0009] In a gear mechanism according to one aspect of the present invention, the direction from the center of rotation of the first second gear to the center of rotation of the last second gear intersects with the extension of the first axis when viewed in the direction along the second axis. As a result, the center of rotation of the last second gear is offset from the position on an extension of the first axis when viewed in the direction along the second axis. Therefore, compared to a state in which the center of rotation of the last second gear is located at the position on an extension of the first axis when viewed in the direction along the second axis, the arrangement area of ​​the components necessary for transmitting rotation from the first axis side to the output side is reduced.

[0010] In the gear mechanism of the present invention, the angle formed by a line connecting a rotation center of the first second gear and a rotation center of the last second gear and the first axis may be a right angle when viewed in a direction along the second axis.

[0011] In the gear mechanism of the present invention, the first gear group may include a first bevel gear attached to the first shaft, and a second bevel gear attached to the second shaft and meshing with the first bevel gear.

[0012] The above configuration may include a first case that houses the first gear group, a second case that houses the second gear group and is attached to the first case, and an output section case that houses an output section having a third shaft that is the output side and is attached to the second case at a position close to the first case, and has a cut surface in which the thickness of a wall portion formed in a circumferential direction relative to the third shaft is reduced only at a portion close to the first case.

[0013] According to the gear mechanism of the present invention, the output section is disposed around the third shaft, and the output section case includes a wall portion surrounding the radially outer side of the output section disposed around the third shaft. The wall portion of the output section is disposed approximately around the entire circumferential direction of the third shaft. The wall portion of the output section has a substantially uniform thickness in the radial direction of the third shaft, but is reduced only in a portion adjacent to the first case. Specifically, the wall portion of the output section is substantially cylindrical, and the portion facing the first case is formed with a cut surface that is flat and corresponds to the side surface of the first case. This reduces the distance between the side surface of the first case and the wall portion of the output section, thereby reducing the distance from the third shaft to the side surface of the first case when viewed in the direction along the second axis.

[0014] In the gear mechanism of the present invention, the dimension of the first case in the direction along the first axis as viewed in the direction along the second axis can be smaller than the dimension of the output case in the direction along the first axis as viewed in the direction along the second axis.

[0015] A gear mechanism according to another aspect of the present invention includes a first axis, a second axis that forms an angle with the first axis, a third axis whose axial direction is the same as the axial direction of the second axis, a first gear group having a plurality of first gears that transmit the rotation of the first axis to the second axis, and a second gear group having a plurality of second gears that transmit the rotation of the second axis to the third axis, in which a straight line connecting a center of rotation of a first second gear that is located closest to the second axis among the plurality of second gears and a center of rotation of a last second gear that is located closest to the third axis intersects the first axis when viewed in a direction along the second axis.

[0016] In a gear mechanism according to another aspect of the present invention, the direction from the center of rotation of the first second gear to the center of rotation of the last second gear intersects with the extension of the first axis when viewed in the direction along the second axis and the third axis. As a result, the center of rotation of the last second gear is offset from the position on an extension of the first axis when viewed in the direction along the second axis and the third axis. Therefore, compared to a state in which the center of rotation of the last second gear is located at the position on an extension of the first axis when viewed in the direction along the second axis and the third axis, the arrangement area of ​​the components necessary for transmitting rotation from the first axis side to the third axis side is reduced. Alternatively, the arrangement area of ​​the components necessary for transmitting rotation from the third axis side to the first axis side is reduced.

[0017] The above configuration may include the first shaft to which a rotational driving force is input, an output section having an output axis in a direction intersecting the input axis of the first shaft and outputting the rotational driving force, the first second gear having the second axis in a direction along the output axis and arranged at a position on an extension of the input axis as viewed in the direction along the output axis, and to which the rotational driving force is transmitted from the first shaft by the first gear group, and the last second gear having the third axis in a direction along the output axis and arranged at a position that intersects with the direction from the center of rotation of the first second gear toward the input axis as viewed in the direction along the output axis, and transmitting the rotational driving force to the output section.

[0018] In the above configuration, the output section has an output axis that intersects with the input axis of the first shaft and is driven by an output rotational drive force; the first second gear has the second axis that extends along the output axis, and the second axis is arranged on a predetermined circumference centered on the position of the output axis as viewed in the direction along the output axis, and the first second gear to which the rotational drive force is transmitted by the first gear group from the first axis that is arranged so as to be tangent to a rotation center of the first second gear on the circumference; and the last second gear has the third axis that extends along the output axis, and the third axis is arranged at a position closer to the output axis than the rotation center of the first second gear as viewed in the direction along the output axis, and the last second gear transmits the rotational drive force to the output section. may also be provided.

[0019] In the above configuration, the first gear group may be bevel gears that mesh with each other.

[0020] A speed reducer according to another aspect of the present invention comprises a first shaft, a second shaft that forms an angle with the first shaft, a first gear group having a plurality of first gears that transmit the rotation of the first shaft to the second shaft, a second gear group having a plurality of second gears that transmit the rotation of the second shaft transmitted from the first shaft side to an output side, wherein a straight line connecting the center of rotation of a first second gear that is located closest to the second shaft among the plurality of second gears and the center of rotation of a last second gear that is located closest to the output side forms an angle with the first shaft when viewed in a direction along the second axis, a rotary drive source that rotationally drives the first shaft, and a reduction unit on the output side that outputs the rotation of the last second gear.

[0021] In a reducer according to another aspect of the present invention, the line connecting the center of rotation of the first second gear and the center of rotation of the last second gear located closest to the output side forms an angle with the first axis when viewed along the second axis, thereby reducing the distance from the center of rotation of the last second gear to the farthest point on the contour of the rotary drive source, and therefore reducing the installation area required for installing the reducer when viewed along the second axis. [Effects of the Invention]

[0022] According to the present invention, it is possible to provide a gear mechanism and a reducer that can be made flat and have a small area as viewed along the axial direction. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a plan view showing an embodiment of a gear mechanism and a reducer according to the present invention; [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 2 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 10 is a plan view showing a conventional reducer. DETAILED DESCRIPTION OF THE INVENTION

[0024] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a gear mechanism and a reducer according Fig. 1 is a plan view showing the gear mechanism and the reducer in this embodiment, Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1, and Fig. 3 is a cross-sectional view taken along line III-III in Fig. 1. In the figures, reference numeral 1 denotes the reducer.

[0025] As shown in FIG. 1, the reducer 1 of this embodiment transmits the rotational driving force of a motor (rotary driving source) 10 to a reduction section (output section) 30 via a gear mechanism 20, and outputs the rotational force around the output axis T0 of the reduction section 30 at a predetermined reduction ratio. The direction along the output axis T0 may be referred to as the up-down direction (vertical direction). The speed reducer 1 of this embodiment can be applied to, for example, driving a table of a turntable.

[0026] In the reducer 1, as shown in Figures 2 and 3, the gear mechanism 20 and the reduction unit 30 are housed in a casing 2. The motor 10 is attached to the outside of the casing 2. The motor 10 drives a drive shaft 10a along a drive axis (input axis) T10 extending in a substantially horizontal direction. An input shaft (first shaft) 11 having a coaxial input axis (first axis) is attached to the drive shaft 10a. The input shaft 11 is rotatably supported by the casing 2. The gear mechanism 20 is coupled to the input shaft 11. The reduction unit 30 outputs a rotation speed lower than the rotation speed input from the gear mechanism 20.

[0027] The motor 10 and the gear mechanism 20 are disposed adjacent to each other when viewed in the direction along the output axis T0. Similarly, the gear mechanism 20 and the speed reducer 30 are disposed adjacent to each other when viewed in the direction along the output axis T0. The motor 10 and the speed reducer 30 are positioned substantially overlapping in the up-down direction along the output axis T0. The gear mechanism 20 is positioned adjacent to the motor 10 and the speed reducer 30 in the up-down direction along the output axis T0, but is positioned slightly below them.

[0028] The gear mechanism 20 includes a center gear (last second gear) 22 whose rotation axis is the center axis (third axis) T2, an idler gear (second gear) 23 that meshes with the center gear 22, and an input gear (first second gear) 21 that meshes with the idler gear 23 and receives the driving force from the motor 10 via the input shaft 11. The center gear 22, idler gear 23, and input gear 21 are all spur gears and are arranged along the same horizontal plane.

[0029] An idler axis T3 of the idler gear 23, an input axis (second axis) T1 of the input gear 21, and a center axis T2 of the center gear 22 are all parallel to the output axis T0. The center axis T2 of the center gear 22 coincides with the output axis T0. The center gear 22 rotates about the center axis T2, the idler gear 23 rotates about the idler axis T3, and the input gear 21 rotates about the input axis T1.

[0030] When viewed in the direction along the output axis T0, a straight line L1 connecting the output axis T0 of the reduction gear unit 30 and the input axis T1 of the input gear 21 intersects with a drive axis T10 of the drive shaft 10a and the input shaft 11. In this embodiment, when viewed in the direction along the output axis T0, the straight line L1 connecting the positions of the output axis T0 and the input axis T1 is perpendicular to the drive axis T10 of the drive shaft 10a and the input shaft 11.

[0031] When viewed in the direction along the output axis T0, the drive axis T10 of the drive shaft 10a and the input shaft 11 are tangent to a circle R0 whose center is the position of the output axis T0 of the reduction gear unit 30. When viewed in the direction along the output axis T0, the circle R0 has a radius extending from the position of the output axis T0 of the reduction gear unit 30 to the position of the input axis T1 of the input gear 21. When viewed in the direction along the output axis T0, the drive axis T10 of the drive shaft 10a and the input shaft 11 are tangent to the circle R0 at the position of the input axis T1 of the input gear 21.

[0032] Additionally, when viewed in the direction along the output axis T0, a straight line L2 that passes through the position of the output axis T0 of the reduction gear unit 30 and is parallel to the drive axis T10 of the drive shaft 10a and the input shaft 11 is perpendicular to a straight line L1 that extends from the position of the output axis T0 of the reduction gear unit 30 to the position of the input axis T1 of the input gear 21. In other words, when viewed in the direction along the output axis T0, the drive axis T10 of the drive shaft 10a and the input shaft 11, which is a tangent to the circle R0, is parallel to but offset from the straight line L2 that passes through the position of the output axis T0, which is the center of the circle R0.

[0033] The casing 2 has a base portion (second case) 2a, a first block (first case) 2b, and a second block (output portion case) 2c. The base portion 2a is formed in a plate shape and is disposed along a horizontal plane perpendicular to the output axis T0. The base portion 2a is disposed along the lower surface of the reducer 1. On the upper surface of the base portion 2a, a first block 2b that houses the gear mechanism 20 and a cylindrical second block 2c that houses the reduction unit 30 are disposed side by side as seen in the direction along the output axis T0.

[0034] The first block 2b and the second block 2c are joined to the upper surface of the base portion 2a while being arranged side by side. The first block 2b and the second block 2c protrude upward from the upper surface of the base portion 2a. The first block 2b and the base portion 2a are joined to each other so as to seal the interior of the reducer 1.

[0035] The cylindrical second block 2c is disposed so that its central axis coincides with the output axis T0. The first block 2b is disposed adjacent to the second block 2c. The upper end of the second block 2c is disposed along the upper surface of the reducer 1. The second block 2c is fastened to the upper surface of the base portion 2a by bolts 2j or the like. The second block 2c and the base portion 2a are coupled to each other so as to seal the interior of the reducer 1.

[0036] The cylindrical second block 2c is disposed over substantially the entire circumference in the circumferential direction of the output axis T0. The wall of the output portion is disposed over substantially the entire circumference of the third shaft in the circumferential direction. The second block 2c has a cut surface 2c formed at a position facing the first block 2b. The cut surface 2c is a vertical surface parallel to the output axis T0. Also, the cut surface 2c is a vertical surface parallel to the straight line L2 when viewed in a direction along the output axis T0. That is, the second block 2c is a cylinder whose thickness in the radial direction of the output axis T0 is approximately uniform in the circumferential direction of the output axis T0, and only the portion adjacent to the first block 2b is cut into a flat shape as a cut surface 2c1. Specifically, the second block 2c is a cylinder with a uniform thickness in the radial direction, and the flat cut surface 2c is formed in the portion facing the first block 2b so as to correspond to the facing surface of the first block 2b. As shown in FIG. 2, the second block 2c has a minimum thickness Mc1 at the cut surface 2c that is smaller than the thickness Mc of the other portions.

[0037] The base portion 2a has a plate-shaped first base portion 2a1 and a plate-shaped second base portion 2a2 having a smaller contour than the first base portion 2a1. The first base portion 2a1 has a contour that allows both the first block 2b and the second block 2c to be attached. The second base portion 2a2 has a contour that corresponds to the contour of the first block 2b, and as will be described later, is fitted integrally into the first base portion 2a1 in a region that corresponds to the first block 2b. The first base portion 2a1 and the second base portion 2a2 are coupled to each other so as to seal the internal space 28b of the reducer 1. The first base portion 2a1 is formed to be thicker than the second base portion 2a2 so that the second base portion 2a2 can be fitted therein, as will be described later. The second base portion 2a2 is exposed on the lower surface of the reducer 1. The second base portion 2a2 is integrally joined to the first base portion 2a1 at a position opposite to the first block 2b in the up-down direction.

[0038] The first block 2b has a first block side portion 2b1 integrally joined to the upper surface of the first base portion 2a1, and a first block plate 2b2 integrally joined to the upper surface of the first block side portion 2b1. The first block side portion 2b1 protrudes upward from the upper surface of the plate-shaped first base portion 2a1. The first block plate 2b2 is coupled to the first block side portion 2b1 so as to close the interior of the first block side portion 2b1. The first block plate 2b2 is disposed substantially parallel to the first base portion 2a1 and the second base portion 2a2. The first block plate 2b2 is disposed along the upper surface of the reducer 1. An end of an input shaft 11 that transmits the rotational driving force of a motor 10 to the gear mechanism 20 penetrates the first block 2b. The input shaft 11 faces horizontally.

[0039] The motor 10 has a drive shaft 10a. The motor 10 is fixed to the side of the first block side portion 2b1. The tip of the drive shaft 10a is the input shaft 11 that penetrates the casing 2. A press-fit hole 11a is formed in the outer end surface of the input shaft 11, into which the drive shaft 10a of the motor 10 is fitted. The motor 10 is fixed to a motor support member 26 attached to the first block 2b. The drive shaft 10a of the motor 10 is inserted into the press-fit hole 11a of the input shaft 11 with its drive axis T10 extending horizontally (in a direction parallel to the base portion 2a). The motor 10 is located slightly above (towards the first block 2b) the upper outer surface of the base portion 2a.

[0040] A driving gear (first bevel gear, first gear) 11b is attached to the tip end of the input shaft 11. The drive gear 11b has teeth formed on the outer end of a disk-shaped portion that protrudes radially from the outer circumferential surface of the input shaft 11. The drive gear 11b meshes with a driven gear (second bevel gear, first gear) 11c. The drive gear 11b and the driven gear 11c are bevel gears. The drive gear 11b and the driven gear 11c are not limited to bevel gears, but may be any gears that are positioned such that the drive axis T10 of the drive gear 11b intersects with the input axis T1 of the input shaft 21a of the driven gear 11c and that can transmit driving force from the drive gear 11b to the driven gear 11c. The driven gear 11c rotates around the input shaft 21a, which extends vertically. The driven gear 11c is disposed adjacent to the second block 2c in the vertical direction of the input shaft 21a.

[0041] The input shaft 21a is a shaft member that extends linearly and concentrically with the rotation axis of the driven gear 11c. The input shaft 21a is supported by a bearing 21g (described later) with the input axis T1 perpendicular to the drive axis T10 of the input shaft 11. In other words, the input shaft 21a is rotatably supported by the casing 2. In this embodiment, the drive axis T10 of the input shaft 11 is parallel to the top surface of the reducer 1, and the input axis T1 of the input shaft 21a is perpendicular to the top surface of the reducer 1. The input axis T1 of the input shaft 21a and the drive axis T10 of the input shaft 11 do not necessarily have to be perpendicular to each other, but may have any other positional relationship other than parallel. For example, the drive axis T10 of the input shaft 11 may be tilted vertically so that the motor 10 side is lower than the horizontal position.

[0042] The driven gear 11c has a disk-shaped portion that protrudes radially from the outer circumferential surface of the input shaft 21a, and has teeth formed on the outer end thereof. The outer end of the driven gear 11c is inserted into an expanded diameter portion 28d1 formed in the first block 2b. As will be described later, the expanded diameter portion 28d1 is located at the upper end of an internal space 28d formed in the first block side portion 2b1, and is closed by the first block plate 2b2.

[0043] An internal space 28b is formed in the first base portion 2a1 in the middle in the up-down direction. The internal space 28b is formed along a horizontal plane perpendicular to the output axis T0.

[0044] Two through holes 28a and 28d2 are formed in the first base portion 2a1, penetrating the first base portion 2a1 in the up-down direction. Both the through holes 28a and 28d2 communicate with the internal space 28b. The through hole 28a is disposed with the output axis T0 as its center line and is formed in a shape concentric with the cylindrical second block 2c. The through hole 28a penetrates from the internal space 28b to the outside of the lower surface of the reducer 1. The through hole 28d2 is formed at a position corresponding to the center of the input gear 21. The through hole 28d2 communicates from the internal space 28b to an internal space 28d of the first block 2b, which will be described later.

[0045] The internal space 28b accommodates the input gear (first second gear) 21, idler gear (second gear) 23, and center gear (last second gear) 22 of the gear mechanism 20 in a state where they mesh with one another. The internal space 28b has a planar contour shape that is continuous with a portion formed in a shape concentric with the input shaft 21a, a portion formed in a shape concentric with the idler shaft 23a, and a portion corresponding to a shape concentric with the center gear 22.

[0046] In internal space 28b, as gear mechanism 20, input gear 21 is connected to input shaft 11 that transmits rotational driving force from motor 10. Idler gear 23 meshes with input gear 21 inside internal space 28b and is rotatably held by first base portion 2a1 and second base portion 2a2. Center gear 22 is located inside internal space 28b and meshes with idler gear 23 to transmit the rotation of input gear 21.

[0047] The center gear 22 has a larger diameter than the input gear 21 and is set to have a larger number of teeth than the input gear 21. Therefore, the rotation of the input gear 21 caused by the motor 10 is reduced to a predetermined reduction ratio and transmitted to the center gear 22 in that state.

[0048] An opening 28b1 is formed in the first base portion 2a1 at a lower position in the internal space 28b that faces the input gear 21 and the idler gear 23. The second base portion 2a2 is fitted from below into the opening 28b1, closing it. The second base portion 2a2 is fixed at a position where it is inserted partway into the internal space 28b in the up-down direction.

[0049] The first base portion 2a1 has an expanded-diameter portion 28b2 formed at the edge of the downward-facing opening 28b1 of the internal space 28b, the expanded-diameter portion 28b2 having a step. A flange portion 2a2a formed to protrude from the periphery of the second base portion 2a2 is fitted into the expanded-diameter portion 28b2. In this state, the surfaces of the expanded-diameter portion 28b2 and the flange portion 2a2a, which face each other in the vertical direction, contact each other. This fixes the position of the second base portion 2a2 relative to the first base portion 2a1 in the vertical direction. The expanded-diameter portion 28b2 may extend to the edge that forms the outline of the first base portion 2a1 in the horizontal direction. A sealing means such as an O-ring may be provided around the periphery of the opening 28b1, above the flange portion 2a2a.

[0050] In the second base portion 2a2, a support hole 21f and a support hole 23f, each having a circular cross section and a bottom, are formed apart from each other on the surface that faces the inner side of the internal space 28b. A bearing 21g is mounted in the support hole 21f. The bearing 21g is attached to the inner peripheral surface of the support hole 21f. The bearing 21g supports the lower end of the input shaft 21a. The input shaft 21a has an input axis T1 in the up-down direction along the output axis T0. The lower end of the input shaft 21a is inserted into the support hole 21f. The input gear 21 is attached to the input shaft 21a close to the lower end. The support hole 23f rotatably supports the idler shaft 23a. The idler shaft 23a has an idler axis T3 extending in the vertical direction along the output axis T0. The lower end of the idler shaft 23a is inserted into the support hole 23f. An idler gear is connected to the idler shaft 23a.

[0051] An internal space 28d extending in the vertical direction is formed at a position facing the support hole 21f of the first block side portion 2b1. The internal space 28d extends in the vertical direction, and its lower end communicates with the internal space 28b via a through-hole 28d2. The internal space 28d has a circular cross section corresponding to the through hole 28d2. The upper end of the internal space 28d is closed by the first block plate 2b2. A support hole 21h with a circular cross section and a bottom is formed in the lower surface of the first block plate 2b2, which is inside the internal space 28d. A bearing 21g is mounted in the support hole 21h. The bearing 21g is attached to the inner circumferential surface of the support hole 21h. The bearing 21g supports the input shaft 21a. The upper end of the input shaft 21a is inserted into the support hole 21h.

[0052] In the first block 2b, an expanded diameter portion 28d1 is formed at the upper end of the internal space 28d. The expanded diameter portion 28d1 houses the driven gear 11c below the bearing 21g. The lower end of the first block plate 2b2 is fitted into the upper end of the internal space 28d. A flange portion 2b2a is provided around the upper end of the first block plate 2b2, protruding radially outward. The flange portion 2b2a contacts the upper end of the first block side portion 2b1, thereby fixing the vertical position of the first block plate 2b2 relative to the first block side portion 2b1. At the same time, the first block side portion 2b1 and the first block plate 2b2 are tightly fitted together, sealing the internal space 28d. A sealing means such as an O-ring may be provided on the outer circumferential surface of the first block plate 2b2 at a position below the flange portion 2b2a and inserted into the first block side portion 2b1.

[0053] In the first block 2b, a bearing 21g that supports the axial center position of the input shaft 21a is attached near the lower end of the internal space 28d. The bearing 21g is attached to the inner circumferential surface of the internal space 28d in the first block side portion 2b1. A downwardly protruding rib 2b4 is formed at the lower end of first block side portion 2b1, which corresponds to the lower end position of internal space 28d, around through hole 28d2. Protruding rib 2b4 is inserted into through hole 28d2 and is used to position first block side portion 2b1 and first base portion 2a1.

[0054] In the first block 2b, a horizontally extending through-hole 28d4 is formed at a position in the internal space 28d corresponding to the expanded diameter portion 28d1 in the up-down direction and below the expanded diameter portion 28d1. The through-hole 28d4 extends toward the motor 10. The drive-side gear 11b is housed inside the through-hole 28d4. An input shaft support portion 25 is formed outside the through-hole 28d4, contiguous with the first block side portion 2b1, at a position surrounding the input shaft 11. The input shaft support portion 25 is cylindrical and surrounds the input shaft 11, and a bearing 24 is disposed inside the input shaft support portion 25. The bearing 24 rotatably supports the input shaft 11. A motor support member 26 is fixed to the outside of the input shaft support portion 25. The input shaft support portion 25 has an interior diameter corresponding to the through-hole 28d4. The input shaft support portion 25 and the first block side portion 2b1 house the input shaft 11 and the drive-side gear 11b and are sealed from the outside.

[0055] An opening 28b3 is formed in the first base portion 2a1 on the upper side of the internal space 28b facing the center gear 22. The opening 28b3 is closed by the second block 2c and the speed reducer portion 30. The opening 28b3 is formed in a planar contour shape that is concentric with the second block 2c and the center gear 22 about the output axis T0.

[0056] In the internal space 28b, the center gear 22 is rotatably supported by a cylindrical body 34. The cylindrical body 34 passes through the internal space 28b in the vertical direction. The cylindrical body 34 is disposed around the output axis T0. The cylindrical body 34 passes through the reducer 1 in the vertical direction. The lower end of the cylindrical body 34 is fitted into the through-hole 28a. A seal member 34b may be provided between the lower end of the cylindrical body 34 and the inner surface of the through-hole 28a. A flange portion 34a exposed on the upper surface of the reduction unit 30 is formed on the upper end of the cylindrical body 34. The flange portion 34a is formed to be recessed downward with respect to the upper surface of the reducer 1. The cylindrical body 34 is disposed approximately in the center of the opening 28b3.

[0057] A coaxial gear 22d is formed integrally with the center gear 22. The gear 22d has a smaller number of teeth and a smaller diameter than the center gear 22. The center gear 22 and gear 22d can rotate integrally around the cylindrical body 34. The gear 22d is disposed above the center gear 22. The gear 22d is disposed closer to the speed reducer 30 than the center gear 22. The gear 22d is on the input side to the speed reducer 30. The gear 22d is housed inside the opening 28b3. The lower end of the center gear 22 is rotatably supported near the through hole 28a via a bearing 34c. The upper end of the center gear 22 is rotatably supported relative to the speed reducer 30 via a bearing 34c.

[0058] The speed reducer portion 30 is housed in a cylindrical second block 2c fixed to the first base portion 2a1. The speed reducer 30 may be, for example, an eccentric oscillation type speed reducer mechanism. The speed reducer 30 has a carrier 33 disposed inside the second block 2c and a transmission shaft 31 that rotates in conjunction with the rotation of the center gear 22.

[0059] The carrier 33 is rotatable relative to the second block 2c around the output axis T0. Specifically, the relative rotation between the second block 2c and the carrier 33 is permitted by a bearing 36 provided between the inner periphery of the second block 2c and the outer periphery of the carrier 33. The carrier 33 is exposed on the upper surface of the speed reducer 30. The carrier 33 forms the output side of the speed reducer 30. The lower end of the speed reducer 30 faces the opening 28b3. A cylindrical body 34 passes through the center of the carrier 33. The axis of the carrier 33 coincides with the output axis T0, which is the axis of the cylindrical body 34. The cylindrical body 34 may be fixed to the carrier 33, for example.

[0060] The transmission shaft 31 serves as the input side of the speed reducer 30 to which the rotational driving force is transmitted from the center gear 22. The transmission shaft 31 is rotatably attached to the carrier 33 with its axis parallel to the output axis T0. The speed reducer 30 rotates the second block 2c and the carrier 33 relative to each other at a speed slower than the rotational speed of the transmission shaft 31, based on the rotation of the transmission shaft 31. The transmission shaft 31 is provided with a transmission gear 32 that meshes with the gear 22d. The transmission gear 32 is a spur gear.

[0061] The reducer 1 of this embodiment may be fixed to a flat reducer mounting surface. In this state, a turntable or the like may be placed on the upper surface of the carrier 33. In this case, the turntable is fixed to the upper surface of the carrier 33 by fastening bolts.

[0062] In this speed reducer 1, when the motor 10 is driven, the drive shaft 10a rotates, causing the input shaft 11, which is coaxially integrated with the drive shaft 10a, to rotate. This drives the driven gear 11c, which meshes with the drive gear 11b provided on the input shaft 11, and causes the input shaft 21a of the gear mechanism 20 to rotate around the input axis T1. When the input shaft 21a rotates, the input gear 21 connected to the input shaft 21a rotates around the input axis T1. The rotation of the input gear 21 causes the idler gear 23 meshed with the input gear 21 to rotate around the idler shaft 23a. When the idler gear 23 rotates, the center gear 22 meshed with the idler gear 23 rotates around the output axis T0. When the center gear 22 rotates, the gear 22d, which is coaxially integrated with the center gear 22, rotates. This causes the transmission gear 32 meshing with the gear 22d to rotate, which in turn causes the transmission shaft 31 integrated with the transmission gear 32 to rotate. The rotation of the transmission shaft 31 causes the second block 2c, which is the outer cylinder of the speed reducer 30, and the carrier 33 to rotate relatively at a speed slower than the rotational speed of the transmission shaft 31. This causes the turntable to rotate.

[0063] In the reducer 1 of this embodiment, when viewed in the direction along the output axis T0, the line L1 and the drive axis T10 are perpendicular to each other, and the line L1 and the line L2 are perpendicular to each other. The line L2 and the drive axis T10 are parallel to each other but offset from each other. As a result, in the reducer 1 of this embodiment, when viewed in the direction along the output axis T0, the distance from the position of the output axis T0, which is the center of the reducer 1, to the farthest point on the outline of the motor 10 is the distance RT shown in FIG.

[0064] FIG. 4 is a plan view showing a conventional reducer. In contrast to the reducer 1 of this embodiment shown in Fig. 1, in a conventional reducer, as shown in Fig. 4, when viewed in the direction along the output axis T0, the straight line from the position of the output axis T0 of the reduction unit 30 to the position of the input axis T1 of the input gear 21 coincides with the drive axis T10 of the drive shaft 10a and the input shaft 11. In this case, the distance from the position of the output axis T0, which is the center position of the reducer 1, to the farthest point on the outline of the motor 10 is the distance RT0 shown in Fig. 4. Although the arrangement is different in FIG. 4, the same reference numerals are used to designate corresponding components.

[0065] In the configuration shown in FIG. 4, the distance RT is shorter than the distance RT0 by the amount that the straight line L1 intersects with it at right angles. Comparing these, it is clear that in this embodiment, the area in the horizontal plane required for arranging the reducer 1 can be reduced. As a result, in the conventional configuration shown in FIG. 4, the reducer could not be arranged so as to be hidden by the table unless the turntable had a diameter of RT0. However, in this embodiment, it is possible to arrange the reducer 1 so as to be hidden by the table, even for a turntable with a diameter of RT0 and a small planar contour. Therefore, the radial size of the reducer 1 can be reduced compared to a configuration in which the drive shaft 10a passes through the output axis line T0.

[0066] The gear mechanism of the present invention can have an input shaft that inputs a rotational driving force, an output section that has an output axis that intersects with the input axis of the input shaft and that outputs the rotational driving force, an input gear that has an input axis that is along the output axis and is located at a position that is an extension of the input axis when viewed in the direction along the output axis, and that transmits the rotational driving force from the input shaft, and a center gear that has a center axis that is along the output axis and is located at a position that intersects with the position of the input axis with respect to the direction from the position of the input axis toward the input axis when viewed in the direction along the output axis, and that transmits the rotational driving force to the output section.

[0067] According to this, when viewed in the direction along the output axis, the direction from the input axis to the center axis intersects with the direction in which the input axis extends. As a result, when viewed in the direction along the output axis, the position of the output axis is offset from the position where the input axis is extended. Therefore, compared to a state in which the output axis is positioned at the position where the input axis is extended when viewed in the direction along the output axis, the layout area of ​​the components necessary for transmitting the rotational driving force from the input side to the output part is reduced. In other words, the layout area required to include the furthest point from the output axis to the contour of the rotational driving source on the input side is reduced.

[0068] In the present invention, the input shaft and the rotary shaft of the input gear can transmit driving force by means of bevel gears that mesh with each other. This allows the size of the arrangement between the output section and the rotary drive source on the input side to be shortened when viewed in the direction along the output axis, and also allows the gear mechanism to be flattened.

[0069] The gear mechanism of the present invention can include an input shaft that inputs a rotational driving force, an output section that has an output axis that intersects with the input axis of the input shaft and is driven by the output rotational driving force, an input gear that receives the rotational driving force from the input shaft and has an input axis that is aligned with the output axis and is arranged on a predetermined circumference centered at the position of the output axis when viewed in the direction along the output axis so as to be tangent to the input axis on the circumference, and a center gear that transmits the rotational driving force to the output section and has a center axis that is aligned with the output axis and is arranged at a position closer to the output axis than the input axis when viewed in the direction along the output axis.

[0070] According to this, when viewed in the direction along the output axis, the direction from the input axis to the center axis is aligned radially relative to the position of the output axis, which is the center of the circumference. Also, when viewed in the direction along the output axis, the direction of extension of the input axis, which is the tangent to the circumference, is parallel to and offset from the line passing through the position of the output axis, which is the center of the circumference. As a result, when viewed in a direction along the output axis, the direction in which the input axis extends intersects with the direction from the position of the input axis to the position of the center axis. Therefore, it is possible to reduce the arrangement area, which is the diameter dimension of the circumference when viewed in the direction along the output axis and the furthest position on the outline of the rotary drive source in the direction in which the input axis extends.

[0071] In this embodiment, the reducer 1 is configured to be placed on a surface extending in the horizontal direction and is used to drive a turntable, but the configuration and use are not limited to this. The reducer 1 in this embodiment may also be configured to be fixed to an attachment surface extending in a direction other than the horizontal direction. Furthermore, in the speed reducer 30, the output side has been described as being the carrier 33, but this configuration is not limited to this, and it is sufficient that either the carrier 33 or the cylindrical second block 2c is the output side. [Industrial Applicability]

[0072] The gear mechanism according to the present invention is not limited to being applied to the reducer 1 of the above-described embodiment, but may be applied to any machine or device. [Explanation of symbols]

[0073] 1...Reducer 2...Casing 2a...Base part (second case) 2a1...First base section 2a2...Second base part 2b...First block (first case) 2b1...Side of the first block 2b2...First block board 2c...Second block (output case) 10...Motor (rotational drive source) 10a...Drive shaft 11...Input shaft (first shaft) 11b...Drive gear (first bevel gear, first gear) 11c...Driven gear (second bevel gear, first gear) 20...Gear mechanism 21...Input gear (first second gear) 21a...input axis (second axis) 22...Center gear (last second gear) 22a...Center shaft (third shaft) 23...Idler gear (second gear) 23a...Idler shaft 30…Reduction part (output part) T0…Output axis line T1...input axis (second axis) T2...Center axis (third axis) T10...Drive axis, input axis (first axis)

Claims

1. A gear mechanism comprising: a base portion having a first base portion and a second base portion facing the first base portion, and forming an internal space between the first base portion and the second base portion; The first axis and a second axis that forms an angle with the first axis; a third axis having an axial direction in the same direction as the axial direction of the second axis; a first gear group having a plurality of first gears that transmit rotation of the first shaft to the second shaft; a second gear group including a plurality of second gears that transmit rotation of the second axis to the third axis, wherein a line connecting a rotation center of a first second gear located closest to the second axis among the plurality of second gears and a rotation center of a last second gear located closest to the third axis intersects with the first axis when viewed in a direction along the second axis; Equipped with the plurality of second gears include an idler gear located between the first second gear and the last second gear in the internal space and meshing with the first second gear and the last second gear, the gear mechanism includes an idler shaft connected to the idler gear, the idler gear is rotatable about the idler shaft; The idler shaft has a lower end and an upper end opposite to the lower end, The lower end of the idler shaft is supported by the second base portion, a gear mechanism in which the upper end of the idler shaft is connected to the idler gear and faces the first base portion with a gap therebetween;

2. the first shaft to which a rotational driving force is input; an output section having an output axis that intersects with the input axis of the first shaft and that outputs a rotational driving force; the first second gear having the second shaft in a direction along the output axis and disposed at a position on an extension of the input axis as viewed in the direction along the output axis, to which a rotational driving force is transmitted from the first shaft by the first gear group; the last second gear, which has the third axis in a direction along the output axis and is disposed at a position where the third axis intersects with a direction from the rotation center of the first second gear toward the input axis as seen in the direction along the output axis, and transmits a rotational driving force to the output section; 2. The gear mechanism according to claim 1, comprising:

3. the first shaft to which a rotational driving force is input; an output section having an output axis in a direction intersecting with the input axis of the first shaft and being driven by an output of a rotational driving force; the first second gear to which a rotational driving force is transmitted by the first gear group from the first shaft, which has the second shaft in a direction along the output axis and is arranged on a predetermined circumference centered on the position of the output axis as viewed in the direction along the output axis, so that the second shaft is tangent to a rotation center of the first second gear on the circumference; the last second gear having the third shaft in a direction along the output axis and arranged at a position closer to the output axis than the rotation center of the first second gear as seen in the direction along the output axis, and transmitting a rotational driving force to the output section; 2. The gear mechanism according to claim 1, comprising:

4. 4. A gear mechanism according to claim 1, wherein the first gear group comprises bevel gears that mesh with each other.

5. A reducer, a base portion having a first base portion and a second base portion facing the first base portion, and forming an internal space between the first base portion and the second base portion; The first axis and a second axis that forms an angle with the first axis; a third axis having an axial direction in the same direction as the axial direction of the second axis; a first gear group having a plurality of first gears that transmit rotation of the first shaft to the second shaft; a second gear group including a plurality of second gears that transmit rotation of the second axis to the third axis, wherein a line connecting a rotation center of a first second gear located closest to the second axis among the plurality of second gears and a rotation center of a last second gear located closest to the third axis intersects with the first axis when viewed in a direction along the second axis; a rotary drive source that rotates the first shaft and is an input side of the reducer; a reduction unit that outputs the rotation of the last second gear and is an output unit of the reducer; Equipped with the plurality of second gears include an idler gear located between the first second gear and the last second gear in the internal space and meshing with the first second gear and the last second gear, the reducer includes an idler shaft connected to the idler gear, the idler gear is rotatable about the idler shaft; The idler shaft has a lower end and an upper end opposite to the lower end, The lower end of the idler shaft is supported by the second base portion, The upper end of the idler shaft is connected to the idler gear and faces the first base portion with a gap therebetween.

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