JPH0826920B2 - Flexible mesh power transmission device - Google Patents

Description

Detailed Description of the Invention TECHNICAL FIELD OF THE INVENTION

The present invention relates to an improvement in a flexible mesh type power transmission device suitable for use as a speed reducer or a cam device.

[Prior art]

Conventionally, as a device of this type, a flexible flexspline having a large number of teeth on the outer periphery is fixed to the outside of an elliptical orbit rolling bearing fixed to a drive shaft, and further meshes with the teeth of the flexspline. As described above, the circular circular spline having a large number of teeth on the inner periphery and having rigidity is designed to obtain a considerably large reduction ratio in correlation with the number of teeth in mesh with each of the teeth, and is structurally lightweight and lightweight. There are some that can be miniaturized. However, while the inner and outer rings of the elliptical orbit rolling bearing have an elliptical shape, the retainer has a perfect circular rigidity, so the rolling position of the balls formed between the inner and outer rings is The inner surface of the retainer approaches the outer surface of the inner ring when it reaches the longest position (hereinafter referred to as the long axis position) from the center position, and conversely, the shortest position from the center position of the ball rolling position (hereinafter referred to as the short axis position). In addition to the outer surface of the retainer approaching the inner surface of the outer ring, the retainer itself holds many balls between the inner and outer rings, but there is considerable dimensional play between the inner and outer rings. Therefore, with the movement of the retainer due to the rolling of the ball, the retainer and the inner and outer rings are in frictional contact with rattling due to slight vibrations in the approaching portion. The frictional contact between the retainer and the outside, as the elliptical orbit rolling bearing itself, is one of the factors that generate vibration noise and unnecessary friction torque. In addition, if such lubrication of the friction portion is not properly performed, considerable friction occurs, wear powder is generated, and normal rotation of the bearing can be prevented. In particular, in an environment where lubrication with oil or grease cannot be performed, the friction torque and abrasion powder generated by the frictional contact between the retainer and each part have a great influence, which may cause a problem in performance.

[Problems to be Solved by the Invention]

The present invention has been made in view of the above points, and minimizes frictional contact between a retainer and an inner / outer ring in an elliptical orbit rolling bearing, and thus friction of the frictional contact portion during driving of the flexible meshing power transmission device. This is intended to reduce the torque and wear and eliminate the above-mentioned conventional drawbacks.

[Means for Solving the Problems]

That is, according to the present invention, a large number of balls are interposed between a flexible outer ring and a rigid elliptical inner ring, and a rigid core provided between the outer ring and the inner ring and having the rigidity to hold the balls. A circular retainer and a narrower portion, which is smaller than the diameter of the ball in the inner peripheral direction for holding each ball, and an outer-side trumpet, which is larger than the size of the ball in the outer peripheral direction, in the retainer. -Shaped orbital rolling bearing having a pocket having a circular cross-section opening, a flexible flexspline having a large number of teeth around the outer ring, and a flexspline provided on the outer periphery of the flexspline. A rigid circular spline having a large number of teeth on its inner circumference so as to mesh with a large number of teeth, and the pocket when the pocket is in the minor axis position of the outer ring and the inner ring. The narrow portion of the pocket abuts on the ball held in the pocket to restrain the ball, and the retainer holds the retainer at a predetermined position where the retainer does not contact the outer ring and the inner ring relatively. A flexible mesh type power transmission device characterized by the above is provided.

DETAILED DESCRIPTION OF THE INVENTION

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to an embodiment with reference to the drawings. The drive shaft (1) includes a hub (2), a plug (3) and an elliptical orbit rolling bearing (4 ) (hereinafter referred to as a bearing). Is formed. The bearing (4)
Is an elliptical rigid inner ring (4a) and this inner ring (4a)
A flexible outer ring (4b) on the outer side of the ball, and a large number of balls (4) arranged between the inner and outer rings (4a) and (4b).
c) ... and a retainer (4d) that holds these balls (4c). The retainer (4d) is a rigid member having a perfect circular shape and is provided with pockets (4e) for holding the balls (4c) in a fixed position. This pocket (4e) is formed into a perfect circle, has a narrow portion (4f) on the inner side with respect to the center of the circle on the circumference, and has a trumpet shape that is larger than the diameter of the ball on the outer side. The opening having a circular cross section is formed. The inner and outer rings (4a) and (4
b) Rolling position of balls (4c) between the bearings (4 )
When it comes to the shortest position (hereinafter referred to as the short axis position) from the center position of the, the narrow portion (4f) comes to a relative position to restrain the ball (4c) held in this pocket (4e). It is like this. That is, when the ball (4c) is in the short axis position, the narrow portion (4f) contacts the ball (4c) and restrains the ball (4c). This relatively restricts the movement of the retainer (4d) itself. On the other hand, when the ball (4c) is in the long axis position, the narrow portion (4f) is the narrow portion by the dimensional difference between the major axis and minor axis radii of the inner ring (4a) (and the outer ring (4b)). (4f) moves away from the ball (4c). A known cup-shaped flexspline (5) is fitted and fixed to the outside of the outer ring (4b) of the bearing (4 ).
The plug (3) has an appropriate elliptical rigidity. As shown in FIG. 3, the flexspline (5) is ring-shaped and has a flexibility (5a) ... A circular spline (6) having a large number of teeth (6a) formed on the inner circumference is provided on the outer periphery of the flexspline (5) so as to mesh with the teeth (5a) of the flexspline. belongs to. That is, the teeth (5a) formed on the flexspline (5) and the teeth (6a) formed on the circular spline (6) are provided at the same pitch, and the teeth on the side of the circular spline (6). The number of teeth is slightly larger than the number of teeth on the side of the flexspline (5). With this structure, when the drive shaft (1) rotates, the inner ring (4a) simultaneously rotates via the hub (2) and the plug (3). This inner ring (4
a) will rotate while remaining elliptical. This rotation causes the outer ring (4b) to flex and undulate through the balls (4c), so that the tooth-like portions of the circular spline (6) mesh with each other only on the major axis side. At this time, for example, if there is a difference in the number of teeth between the two teeth, and the flex spline (5) is fixed and the inner ring (4a) rotates once, the circular spline (6) has the difference in the number of teeth, and thus the flex spline (6) It rotates in the direction opposite to the direction 5). Next, the operation will be described. As the inner ring (4a) is driven to rotate, the outer ring (4b) simultaneously changes its direction along the direction of the ellipse of the inner ring (4a) via the balls (4c). That is, the rolling positions of the balls (4c) ... Between the inner / outer rings (4a) and (4b) are moved alternately in the major axis position and the minor axis position. At this time, the narrow portion (4f) of the pocket (4e) of the retainer (4d) with respect to the ball (4c) in the short axis position comes close to the surface of the ball (4c), and the ball (4c) is restrained. Come to do. In other words, the retainer (4d) is relatively restricted in movement by the ball (4c) on the short axis side. This retainer (4d) suppresses so-called dimensional play in the major axis direction and the minor axis direction. To explain the state of restraint of the retainer in detail, the narrow portion of the pocket at the minor axis position of the retainer is formed by an opening having a circular cross section, and the narrow portion of the circular cross section is formed with respect to the ball located in the pocket. Are in line contact with each other, and as a result, the retainer itself is restricted from moving in all directions by the ball. On the other hand, on the major axis, the ball (4c) floats from the pocket (4e) of the retainer (4d) as shown in FIG. That is, while the retainer (4d) is a perfect circle, the inner ring (4a) has an elliptical shape, so that the pocket (4e) of the retainer (4d) is described above from the trajectory of the balls (4c). This is because the dimensional difference shifts inward. At this time, the movement of the ball (4c) is not restricted by the trumpet-shaped opening of the pocket (4e), but since the movement of the retainer itself is restricted at two places on the minor axis side, this retainer is restricted on the major axis side. However, it does not come into contact with the inner or outer ring.

【The invention's effect】

According to the present invention, as described above, a large number of balls are interposed between the outer ring having flexibility and the elliptical inner ring having rigidity, and the rigidity for holding the balls provided between the outer ring and the inner ring is improved. The retainer has a perfect circle, and this retainer has a narrow portion smaller than the diameter of the ball in the inner peripheral direction to hold each ball, and outward in the outer peripheral direction larger than the size of the ball. An elliptical orbit rolling bearing having a pocket having a trumpet-shaped opening with a circular cross section, a flexible flexspline having a large number of teeth around the outer ring, and a flexspline provided on the outer periphery of the flexspline. The inner circumference has a rigid circular spline provided with a large number of teeth so as to mesh with a large number of teeth, and the pocket has a short axis position in the outer ring and the inner ring. The narrow portion shaped pocket in contact with the ball held in the pocket, to restrain the ball. As a result, the movement of the retainer itself is relatively held at a predetermined position.
As a result of the movement of the retainer itself in the inner and outer peripheral directions (radial direction) of the bearing being restricted, the retainer does not frictionally contact the inner and outer rings. Further, the narrow portion of the pocket is in line contact with the ball located in the pocket by the narrow portion having a circular cross section as described above, and as a result, the drive shaft direction (thrust direction)
The movement of the retainer is also restricted, and the cause of vibration in the same direction of the retainer itself can be suppressed. Furthermore, since the narrow portion of the pocket is in line contact with the ball surface in a ring shape, the movement of the retainer itself is restricted, and this retainer causes frictional contact with the inner and outer rings to cause rattling noise. In addition, it also suppresses the generation of abrasion powder from the retainer and inner and outer rings as much as possible, and especially it is a high-performance and long-life flexible meshing suitable for use in an environment where lubrication with oil or grease cannot be performed. A power transmission device can be provided. Further, in the elliptical orbit rolling bearing itself, the retainer can restrict the movement of the ball and the retainer at two locations on the minor axis side without mutual restriction of the movement of the ball and the retainer on the major axis side. Therefore, when designing the retainer, it is necessary to maintain only the so-called short-axis side relative position with the ball, especially the dimensional accuracy in the narrow portion of the pocket that abuts the ball. Since the dimensional accuracy is not particularly required, the bearing itself can be easily manufactured. Furthermore, when the inner surface of the pocket of the bearing itself is formed in a tapered shape, it is possible to design so that the tapered surface contacts the center of gravity of the ball located on the so-called major axis. The contact friction between the balls can be further reduced, and this is especially true when the elliptical orbit rolling bearing is used as a flexible meshing type power transmission device with its major axis side in the horizontal position and the ball pushes up smoothly. And, by reducing the wear, a further effect can be exhibited.

[Brief description of drawings]

1 is a front view of a flexible mesh type power transmission device, FIG. 2 is a partial vertical side view of the flexible mesh type power transmission device, and FIG. 3 is a bearing, a flexspline and a circular. FIG. 4 is a front view showing a mutual relationship with a spline, and FIG. 4 is an enlarged view of a portion A in FIG. 1. (4 ) …… Elliptical orbit rolling bearing, (4a) …… Inner ring,
(4B) …… Outer ring, (4c) …… Ball, (4d) …… Retainer, (4e) …… Pocket, (4f) …… Narrow part, (5)…
… Flex Spline, (6) …… Circular Spline.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiro Ohashi 1 Komukai Toshiba Town, Sachi-ku, Kawasaki-shi, Kanagawa Toshiba Komukai Plant (72) Inventor Yasuro Otsubo Komukai Toshiba-cho, Kawasaki-shi, Kanagawa Prefecture 1 Toshiba Corp. Research Institute (56) References Japanese Patent Publication Sho 47-36545 (JP, B1)

Claims (1)

[Claims] 1. A ball which is interposed between a flexible outer ring and a rigid elliptical inner ring, and a rigid circular retainer which is provided between the outer ring and the inner ring and holds the ball. And the retainer has a narrow portion smaller than the diameter of the ball in the inner circumferential direction for holding each ball, and an outward trumpet-shaped cross section larger than the size of the ball in the outer circumferential direction. An elliptical orbit rolling bearing having a pocket having a circular opening, a flexible flexspline provided with a large number of teeth on the outer circumference of the outer ring, and a large number of teeth provided on the flexspline on the outer circumference of the flexspline. A circular circular spline having a large number of teeth on its inner periphery so as to mesh with the inner circumference, and the pocket has a narrower pocket when the outer ring and the inner ring are in the short axis position. The part abuts on the ball held in the pocket to restrain the ball, and the restraint of the ball allows the retainer to be held at a predetermined position so as not to come into contact with the outer ring and the inner ring. A flexible mesh type power transmission device characterized by the above.