JPS61192947A - Symmetry driving type reduction gear - Google Patents

Abstract

PURPOSE:To eliminate backlash, by providing a clearance between outer rings in a double-row ball bearing and applying a pre-load so as to narrow said clearance. CONSTITUTION:A cam 7 externally fits to its peripheral slidably independent double-row deep grooved ball bearings 8a, 8b constituting a wave generator, and the bearing, inserting a ring-shaped elastically deformable spacer 15 to be interposed between outer rings 10a, 10b of the both bearings 8a, 8b, generates a clearance between their inner rings 9a, 9b. A pre-load mechanism 16 applies a pre-load by pressing the inner rings 9a, 9b respectively in the inner direction, that is, in the direction narrowing the clearance. Said pre-load mechanism 16 is constituted by forced contact pressure discs 17a, 17b, slidably arranged on an input shaft 5, and nuts 19a, 19b being screwed to external threads 18a, 18b and pressing the forced contact pressure discs 17a, 17b respectively in their opposite direction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a harmonic drive type reducer, and more particularly to a harmonic drive type reducer that can obtain highly accurate positioning and high rotational rigidity.

[Conventional technology]

As shown in FIGS. 5 and 6, the conventional harmonic drive type reduction gear consists of a wave generator (1), a flexure line (2) disposed outside the wave generator (1), and a pair meshed with the wave generator (1). It is composed of a circular spline +31 (4).

The wave generator (1) has an input shaft (5
) is an oval cam (7) with an insertion hole (6) through which it is inserted.
), and double-row ball bearings (8a) and (81
)). Here, each ball bearing (8a)
, (8b), and its inner rings (9a), (9b) are cams (
7) is fixed to the outer periphery of the outer ring (ioa), (101))
is configured to be elastically deformable via the driveway body (ll&), (111)).

The flexspline (2) is composed of a thin, endless metal elastic body, and its inner peripheral surface is fitted with a ball bearing (8a).
, (8b) o Outer ring (10!L), (10tl) K,
They are fitted without any gaps, and a large number of external teeth αa are carved on one outer circumferential surface at a predetermined pitch.

The circular groove line (3) is composed of a ring-shaped rigid body, and the external tooth α of the flexure line (2) is formed on its inner peripheral surface.
Internal teeth α with the same pitch as a and two more than the number of teeth are carved, and these are the external teeth αa of the flexspline (2).
The teeth fit together in two places: and the long sleeve position.

The circular spline (4) is similarly composed of a ring-shaped rigid body, and internal teeth α◆ with the same pitch and the same number of teeth as the external teeth (2) of the flexus grain (2) are carved on its inner peripheral surface. 12) (D outside fl
They mesh at two locations: lα4 and the long axis position.

Next, regarding the operation of the above conventional example, FIGS. 7(a) to (d)
Explain with reference to. Now, as shown in Figure 7(a) K,
The external teeth (2) at the long sleeve position of the flex spline (2), which have been deformed into an elliptical shape by the wave generator (1) K, are attached to the upper and lower internal teeth of the circular splines (3) and (4), a◆, respectively Assume that they are in mesh (the meshing positions are indicated by arrows 1 and j, respectively). In this state, the external teeth α on the short axis side of the flex spline (2) and the left and right internal teeth of the circular splines +3) and (4), α◆, are completely separated.

From this state, fix the circular spline (3) and
When the input shaft (shape) is rotated clockwise, the cam (7) of the wave generator (1) changes according to the rotation of the input shaft (5).
rotates clockwise, which causes the flexure line (2) to elastically deform, inducing harmonic motion, and its external teeth υ
The meshing position of the internal tooth 0 of the circular gel line (3) sequentially moves clockwise as shown in Fig. 7 ((9), (C) and ((1)). When rotates once, K is the flexspline (2)
will move counterclockwise by the difference in number of teeth between the circular spline (3) and the circular spline (3) (see Figure 7(d)).
〇On the other hand, the Circulus Geline (4) is carved with internal teeth α◆ with the same number of teeth as the external teeth a of the Plexus Gline (2), so even when the wave generator (1) rotates, As shown by arrows m and n in Fig. 7(a) to (1), circular gel line (4) and flexus line (
There is no change in the relative position with 2).

Therefore, when the wave generator (1) rotates once, the circular gel line (3) moves in the opposite direction to the rotation direction of the wave generator (1) by the difference in the number of teeth between the two, and the circular gel line/(4) moves in the opposite direction to the rotation direction of the wave generator (1). follows the movement of the flex spline (2), so an angular displacement corresponding to the difference in the number of teeth occurs between the circular gel line (3) and +41.

Generally, this angular displacement is taken out and adjusted to obtain a desired reduction ratio.

[Problem that the invention seeks to solve]

In the conventional harmonic drive type reducer as described above, the eighth
As shown in the figure, the meshing gap between the external tooth α of the flex spline (2) and the internal tooth α of the circular spline +3), +4) and the ball bearing (8a) that constitutes the wave generator (1) are shown. , (81)), there is a problem of bala crash caused by the radial clearance, and there is a lack of rigidity due to non-uniform meshing of one tooth, which impedes high-precision positioning. In addition, conventional harmonic drive type reducers generally have low rigidity, so each tooth surface receives large stress and easily generates vibration, which is an obstacle to increasing speed.

In order to solve these problems, it may be possible to improve precision by reducing the clearance between the elements that make up the harmonic drive type reducer, but in this case, not only would the cost increase, but it would also be difficult to assemble. Circular spline (3)
, (4) and the wave generator (1) have a new problem that the influence of eccentricity becomes large), which is not practical〇Furthermore, for example, as disclosed in Japanese Patent No. 114051/1982, There is also a method of using multiple harmonic drive type reducers to apply preload in the rotation direction and thereby eliminate backlash, but in this case, the device becomes larger and the ball bearings (8a), ( There was a problem that the effect of eliminating the radial gap in 8b) was small.

The present invention was made in order to solve these problems, and an object of the present invention is to obtain a harmonic drive type speed reducer that has a simple configuration, no backlash, and has high rigidity.

[Means for solving problems]

A harmonic drive type reducer according to the present invention is a harmonic drive type reducer equipped with a wave generator, a flex spline, and a circular gear line, in which the ball bearings constituting the wave generator are configured in double rows, and the outer rings A spacer is inserted between the inner rings, and a preload is applied by the preload mechanism so as to narrow the gap between the inner rings. By inserting a spacer between the outer rings of a ball bearing, a gap is created between the inner rings, and by applying preload between the inner rings using a preload mechanism to narrow this gap, the rolling body is placed on the raceway surface. radially displacing the outer ring and the flexspline, thereby forcing the outer ring and the flexspline radially apart. As a result, the radial gap of the ball bearing is eliminated, and the outer teeth of the flex spline and the inner teeth of the circular spline are brought into close contact with each other to eliminate backlash and increase rotational rigidity.

〔Example〕

FIG. 1 is a sectional view showing an embodiment of the present invention. In the figure, parts corresponding to those of the conventional example are designated by the same reference numerals, and detailed explanation thereof will be omitted.

In this invention, mutually Vc independent double row Mill type ball bearings (ball bearings), (8
b) is fitted onto the outer periphery of the cam (7) so as to be slidable in the axial direction, and a ring-shaped elastically deformable spacer storage space is inserted between the two outer rings (TOA) and (101)). Their inner circle (9
A gap is created between a) and (91)). In this case, the sum of the widths of the ball bearings (8a)% (8b) and the spacer α9 is selected to be wider than the width of the cam (7).

The inner rings (9a), (91)) are the preload mechanism α
e, they are each pressed inward, that is, in a direction that narrows the gap, and a preload is applied.

An example of the preload mechanism t1e is one that is slidably disposed on the input shaft (5) and includes ball bearings (8a), (8b) o an inner ring (9a).
, (91)) are in contact with the outer surfaces of the pressure discs (t7a
), (171)) and male threads (1ea), (181)) formed on both sides of the shaft part inserted into the insertion hole (6) of the cam (7) of the input shaft (5). The discs (t
7a), (171)) Oak pressing in the direction facing the husband)
(toa) and (19b).

To assemble the harmonic drive type reducer according to the present invention having the above configuration, first, a spacer is inserted between the ball bearings (8a), (81)) and the outer rings (toa) and (101)). The input shaft (5) is inserted into the cam (7) with the pressure discs (x7a) and (171) attached to the side surfaces of the cam (7), and then Natsuto (19a
), (19b) to the male screw (t8a) of the input shaft (5), (
18t)) K each Jll sassete pressure welding disc (17a), (
t7b) is the inner ring (9a) of the ball bearing (8a), (8b),
(91)) The wave generator (1) is constructed so as to be in light contact with the wave generator (91).

Next, the flex spline (2) and the circular splines (3) and (4) are meshed, and a wave generator (11
Insert.

Finally, firmly tighten the nuts (x9a), (191)) to connect the inner rings (9a), (9b) of the ball bearings (8a), (81)) via the pressure discs (17a), (17b).
are brought into pressure contact with each other to apply a required preload to the ball bearings (8a) and (8b).

Next, the operation of the above embodiment will be explained.

As mentioned above, at the end of the assembly, nuts (19a), (1
91))) and press the welding disc (x7a), (17
1)) Inner ring (9”) of Niyoshi ball bearings (8a) and (8b)
, (9b) by the spacer (c), the inner rings (9a), (91
)), the driveway bodies (11a) and (11
b) will be pressed against the raceway surface. For this reason, the flexus grain (2), which is also an elastic body, is pushed outward through the outer ring (10a), (IOI)), which is an elastic body, and the outer tooth α of the flexure line (2), which is a rigid body, is expanded outwardly. The internal teeth (11 and a◆) of lines (3) and (4) come into close contact with each other, and as a result, as shown in Fig. 3, preload is applied to the meshing portion of both teeth, and the flexspline (2) External tooth αa and circular spline f3), (4
) internal teeth α: 1. (It is possible to effectively prevent backlash from occurring between the ball bearings (8a), (8b) and the driveway body (111!L), (11b
), the alignment becomes uniform and the radial gap is eliminated.
Rotational rigidity can be increased.

In the above embodiment, the preload mechanism aI includes pressure contact discs (17a), (17b) and nuts (19a), (
19b), and ball bearings (8a), (8b)
Although we have explained the case where the inner rings (9a) and (9b) of However, instead of this, the cam (7) is divided into two in the axial direction to form half-rests (7a), (71)), and the inner rings (9a) of the ball bearings (8a), (sb) are attached to the outer peripheral surfaces of the half-rests (7a) and (71), respectively. ), (9b)
firmly fix the inner rings (9a), (91)) and tighten them with nuts (19a), (191)) so that the half-holes (7a) and (7b) are in close contact with each other, and apply K preload to the inner rings (9a) and (91)). Even if the inner ring (9a) of the ball bearing (8a), (81))
, (9b) may be fixed, and a preload may be applied to the other.

Further, in the above embodiment, the case where a deep groove ball bearing is applied is explained, but the preload mechanism α and
Any ball bearing can be used as long as it has a configuration that allows the stiffness spline (2) to be expanded outward by applying a preload. For example, when an angular contact ball bearing is used. , a larger preload can be applied to increase the rigidity.

Furthermore, in the above embodiment, the case where the present invention is applied to a harmonic drive type reducer having two types of circular splines has been described.
This is fixed and the flex spline (21
The present invention can also be applied to a harmonic drive type reducer configured to connect the output side to the output side.

Furthermore, the shape of the cam I is not limited to an elliptical shape, but can also be formed into a triangular shape or a polygonal shape larger than that. The structure has a spacer inserted between the outer rings of the ball bearing and a preload mechanism that applies preload to narrow the gap between the inner rings. This has the effect of eliminating both the backlash of

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is an enlarged sectional view of the main part of FIG. 1, FIG. 3 is a schematic longitudinal sectional view for explaining the invention in detail, and FIG. 4 5 is a sectional view showing another embodiment of the present invention, FIG. 5 is a sectional view showing a conventional example, FIG. 6 is a schematic axial front view thereof, and FIGS. FIG. 8 is a vertical cross-sectional view schematically showing the problems of the conventional example. In the figure, (1) is a wave generator, (2) is a plexus deline, ( 31, (41 is a circular spline, (5) is an input shaft, (7) is a cam, (8a), (
8b) is a ball bearing, (9a), (91)) is an inner ring, (10
a), (101)) are outer rings, (1ta), (lit))
is the private road body, the function is the external tooth, a3, aa is the internal tooth, α1 is the spacer,
(Ls is a preload mechanism, (17a), (171)) is a pressure contact disk, (19a), (191)) is/g. Note that the same reference numerals in each figure indicate the same or equivalent parts.O Agent Patent Attorney Masuo Oiwa (and 2 others) Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (4)

[Claims] (1) A wave generator having an elliptical or polygonal cam and a ball bearing mounted on the cam, and a flex spline made of an elastic metal body and having external teeth at a predetermined pitch fitted onto the wave generator. , a circular spline having internal teeth having the same pitch as and exceeding the number of teeth of the external teeth of the flexspline, and meshing with the external teeth of the flexspline at at least two points. In the harmonic drive type reducer, the ball bearings are configured in a double row, a spacer is inserted between the outer rings, and a preload is applied to the inner rings of both ball bearings in the axial direction in a direction that narrows the gap between them. A harmonic drive type reducer characterized by being equipped with a preload mechanism. (2) The circular spline has a spline portion having internal teeth having the same pitch and a number of teeth exceeding the external teeth of the flexspline, and a spline portion having the internal teeth having the same pitch and the same number of teeth as the external teeth of the flexspline. A harmonic drive type speed reducer according to claim 1, comprising a spline having internal teeth. (3) The harmonic drive type speed reducer according to claim 1 or 2, wherein the preload mechanism is configured to directly preload the inner ring of the ball bearing. (4) The harmonic drive type speed reducer according to claim 1 or 2, wherein the preload mechanism is configured to preload the inner ring of the ball bearing via a split cam.