JPH0415347A - Planetary roller reduction gear - Google Patents

Abstract

PURPOSE:To reduce the quantity of parts and simplify structure by forming a slot, installing a pre-load ring interposed between a plurality of planetary rollers and a projection part and a pre-load member for pressing the pre-load ring onto the tapered surface of the projection part. CONSTITUTION:A two-stage annular pre-load member 16 is fixed with a projection part 22a by a bolt 15, and an annular spacer 17 is nipped between the member 16 and the projection part 22a. The bolts 15 are installed inside the outside diameter rotary surface of each speed reduction part 10a of each planetary roller 7 - 9 and each auxiliary roller part 12a. A pre-load ring 18 is uniformly pressed on the tapered surface of the projection part 22a by the lower edge part of the member 16, and the diameter of the ring 18 is reduced by reducing the gap of the slot 18a of the ring 18. Accordingly, each speed reduction part 11a of each planetary roller 7 - 9 is pressed against a sun roller 4 side by the inner peripheral surface of the ring 18, while each auxiliary roller part 12a and each speed reduction part 10a are brought in pressure contact with the sun roller 4, and a pre-load is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a planetary roller speed reducer equipped with a plurality of planetary rollers each having a small-diameter shaft portion with roller portions formed at both ends thereof.

[Conventional technology]

Conventionally, as this type of planetary roller speed reducer, there are the following (1) and (2).

(1) As shown in FIG. 6, a plurality of planetary rollers 43 each having large-diameter roller portions 41 and 42 formed at both ends of a small-diameter shaft portion 4o are disposed around a sun roller 44. , which is equipped with two elastic rings (preload rings) 45 and 46 for pressing each large diameter roller portion 41 and 42 of each planetary roller 43 against the sun roller 44 (JP-A-58-
(See the upper left column of page 2 of Publication No. 57554).

(2) As shown in FIG. 7, the plurality of planetary rollers 53 each have a large diameter roller section 52 and a small diameter roller section 51 formed at both ends of a small diameter shaft section 5o.
is arranged around the output shaft (solar roller) 55 of the motor 54, and includes a fixed song (preload ring) 56 for pressing each large diameter roller portion 52 against the output shaft 55, and a fixed song (preload ring) 56 for pressing each large diameter roller portion 52 against the output shaft 55, and a Output ring (preload ring) for pressing each small diameter roller portion 51 against the inner roller 57 whose outer diameter is the tangent circle
58 (see JP-A-60-18651, page 2, lower right column to page 3, upper left column).

[Problem to be solved by the invention]

In the conventional techniques (1) and (2) mentioned above,
Preload is obtained by pressing the two roller parts at both ends of each planetary roller against the sun roller or inner roller using two preload rings, which increases the number of parts and complicates the structure. There is a problem in that it is difficult to align the rotational axis of the planetary roller with the rotational axis of the sun roller.

Furthermore, since a large-diameter preload ring must be used, there is a problem in that the casing, that is, the case, is large.

Furthermore, if a preload is applied to the shaft of each planetary roller with a preload ring having a tapered shape, it is necessary to use a two-piece preload ring due to the mechanical structure, so it is necessary to process the preload song and roughen it. Adjustment work becomes difficult, and furthermore, since the preload member and the bolt cannot be provided inside the outer rotating surface of both ends of each planetary roller, there is a problem that a thick preload ring must be used.

The present invention has been made in view of the above-mentioned problems of the conventional technology, and has a structure that is simple due to a reduction in the number of parts, easy centering, and allows the use of a small diameter and thin preload ring. The purpose is to provide a small planetary roller reducer.

Means for Solving Problem C3) In order to achieve the above object, the planetary roller reducer of the present invention has a sun roller rotated by a drive source, and a large diameter roller portion at both ends of a small diameter shaft portion, a plurality of planetary rollers whose large-diameter roller portions circumscribe the outer peripheral surface of the sun roller; an outer ring having a protruding portion with a tapered surface facing the shaft portion of the plurality of planetary rollers; and a slot formed therein. , a preload ring interposed between the plurality of planetary rollers and the protrusion, and a preload member for pressing the preload ring against the tapered surface of the protrusion.

Further, a preload adjustment mechanism is provided, which includes a bolt for fixing the preload member to the protrusion, and a spacer held between the preload member and the protrusion.

Generally speaking, the bolts of the preload adjustment mechanism are provided inside the outer diameter rotating surfaces of both large diameter roller portions of the two planetary rollers.

[For production]

In the invention according to claim 1 configured as described above, the preload ring is pressed against the tapered surface of the protrusion by the preload member, and the diameter of the preload ring is reduced by reducing the gap between the slots of the preload ring. . As a result, the central shaft portion of each planetary roller is pressed toward the sun roller by the inner circumferential surface of the preload ring, and each large diameter roller portion of each planetary roller is pressed against the sun roller to obtain preload. When the sun roller is rotated by the drive source, each planetary roller pressed by the sun roller is rotated by friction drive. moreover,
The rotation of each planetary roller is transmitted through the preload ring to the outer ring at a reduced speed by friction drive, and the outer ring rotates at a low speed.

In the invention as set forth in claim 2, the thinner the spacer is, the longer the preload member presses down the preload ring, so the reduction rate of the diameter increases accordingly;
The preload increases. Therefore, the preload can be adjusted by loosening the bolt, changing the spacer to a spacer with a different thickness, and then tightening the bolt. Moreover, by using a predetermined spacer, the sliding torque of the outer ring can be set to an appropriate torque.

〔Example〕

Next, an embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1 indicates a control drive motor which is a drive source, and this drive motor 1 is fixed to a motor mounting flange 2a of a base 2 mounted on a fixed table 3. A rotational speed sensor 36 is directly connected to the drive motor 1, and the lower end of a two-stage cylindrical small-diameter sun roller 4 is connected to its output shaft 1a via a coupling Ib. The sun roller 4 is rotatably supported by the base 2 via two bearings 6a and 6b at its upper end large diameter portion, and the outer circumferential surface of the upper small diameter portion is smooth.

1 and 2, a plurality of (three in this embodiment) planetary rollers 7.8.9 are connected to three shafts 25 which are parallel to the rotational axis of the sun roller 4 and fixed to the base 2. (2
The shaft of the book is rotatably supported via two bearings 26a and 26b. Since each of these planetary rollers 7.8.9 has the same construction, one of them will be described below.

The planetary roller 7 has a first deceleration part 10a and an auxiliary roller part 12a, which are large-diameter roller parts, at both ends of a second deceleration part 11a, which is a small-diameter shaft part. The outer circumferential surfaces of the first speed reduction section XOa and the auxiliary roller section X2a of the planetary rollerf are in contact with the outer circumferential surface of the sun roller 4, respectively.

The first speed reducer 10a and the second speed reducer 11a are integrally molded, and their axes coincide. Further, the auxiliary roller portion 12a is provided with a second
It is fixed to the speed reducer 11a. When fixing the auxiliary roller part 12a to the second deceleration part 11a, the two positioning pins 14a and 14b position the auxiliary roller part 12a to the second deceleration part 11a, so that the axis of rotation of the auxiliary roller part 12a and The axis of rotation of the second speed reducer 11a coincides with that of the second speed reducer 11a. Further, the outer circumferential surfaces of the auxiliary roller portion 12a, the second speed reduction portion 11a, and the first speed reduction portion fOa are smooth.

The cylindrical outer ring (output shaft) 22 is connected to each planetary roller 7.8.
An annular protrusion 22a facing the second deceleration part tib of No. 9 is integrally provided inward. This outer ring 22 is rotatably supported at its lower end by the heel 2 via a bearing 26, and accommodates the three planetary rollers 7, 8, and 9 described above. The inner circumferential surface of the protruding portion 22a is a tapered surface 23 that expands upward in the drawing.

A preload ring 18 made of an elastic material is attached to each planetary roller 7.
．． 8.9 and the protrusion 22a. As shown in FIGS. 3A, 3B, and 3C, this preload ring 18 corresponds to the obliquely formed slot 18a, the smooth inner peripheral surface, and the tapered surface 23 of the protrusion 22a. It has a tapered outer peripheral surface, and its inner diameter is equal to the diameter of the circumscribed circle of the second speed reduction part 11a of each of the planetary rollers 7.8.9.

The two-stage annular preload member 16 is fixed to the protrusion 22a by twelve ports 15 arranged at equal pitches, and an annular spacer is provided between the preload member 16 and the protrusion 22a. 17 is being held. The 12 ports 15 are connected to each first reduction part 1 of each planetary roller 7.8.9.
The six-stroke preload ring 18 provided inside the outer rotating surface of each auxiliary roller portion 12a is pressed uniformly against the tapered surface 23 of the protruding portion 22a by the lower end of the preload member 16, and the preload ring 18 is As the gap between the slots 18a becomes smaller, the diameter of the preload ring 18 is reduced.

As a result, each second reduction part 11 of each planetary roller 7.8.9
a is pressed toward the sun roller 4 side by the inner peripheral surface of the preload ring 18, and each auxiliary roller portion 12 of each planetary roller 7.8.9
a and each first speed reducer 10a are in pressure contact with the sun roller 4,
Preload can be obtained. The thinner the spacer 17 is, the longer the length by which the preload ring 18 is pressed down by the lower end of the preload member 16 becomes, so the rate at which the diameter is reduced increases accordingly, and the preload increases. Therefore, after removing the 12 ports 15 from the preload member 16 and changing the spacer 17 to a spacer 17 with a different thickness, the 12 ports 1
By tightening 5, the preload can be adjusted.

As is clear from the above description, the preload adjustment mechanism is composed of the twelve bolts 15, the spacer 17, and the like.

The three pillars 19, 20.21 are connected to each planetary roller 7.8.9.
One end of each is fixed to the upper surface of the base 2 so as to be located between them. An annular support 28 is fixed to the upper end of each company 19, 20, 21, and a shaft-attached fixing member 33 having a shaft 33a and a hole is fixed to this support 28. A bearing 5 is provided on the large circle of the fixed member 33 with a shaft portion, and the upper end portion of the sun roller 4 is rotatably supported by the bearing 5. As a result, the sun roller 4 has both ends bearing the bearings 5, 6a, 6.
Since it is supported by the planetary rollers 7, 8, and 9, it does not swing significantly even if it receives pressing force or preload from each of the planetary rollers 7, 8, and 9. Also,
Since the respective pressing forces from each planetary roller 7.8.9 are equal, the sun roller 4 does not swing around. The annular support plate 29 is fixed to the outer ring 22 so as to be located inside the upper end of the outer ring 22. The main body (casing) of the encoder 27 having a position detection shaft 27a is fixed to a support plate 29 via a support member 31. Further, the position detection shaft 27a of the encoder 27 is connected and fixed to the shaft portion 33a of the shaft portion-attached fixing member 33 via a coupling 32. The cover 30 is fixed to the upper end of the outer ring 22 and is provided for safety.

With these configurations, when the outer ring 22 rotates with respect to the base 2, the position detection shaft 27a of the encoder 27 is detected via the coupling 32, the fixing member 33 with a shaft part, the support base 28, and the three pillars 19, 20° 21. Since the encoder 27 is fixed to the base 2, the position detection shaft 27a itself does not rotate, but the main body of the encoder 27, which is fixed to the outer ring 22, rotates relative to the position detection shaft 27a. Thereby, the rotation angle of the outer ring 22 can be detected by the encoder 27.

As shown in FIG. 4, the CPU 34, digital servo 3
5. The drive motor! , the outer ring 22, the encoder 27, and the rotational speed sensor 36 constitute a digital servo operating circuit. To explain this operation circuit in detail, the target values (commands) for the rotation speed and rotation angle of the outer ring 220 are
When the signals are input from U34 to the digital servo 35, the digital servo 35 starts the drive motor 1, and the drive motor 1 rotates. As a result, the sun roller 4 also rotates, and each planetary roller 7°8.9 and the outer ring 22 also rotate due to frictional drive. The rotation angle of the outer ring 22 is detected by an encoder 27, the rotation speed of the drive motor 1 is detected by a rotation speed sensor 36, and each detected value is fed back to a digital servo 35. As a result,
The digital servo 35 controls the drive motor 1 so that each detected value matches each target value.

Next, a method of adjusting the preload adjustment mechanism will be explained.

A plurality of spacers 17 having different thicknesses are prepared in advance, and the relationship between the thickness of the spacer 17, that is, the preload, and the sliding torque of the outer ring 22 is determined as shown in FIG.

Among the plurality of spacers 17, one spacer 17 whose sliding torque can be set to an appropriate torque is selected.

The sun roller 4, the planetary rollers 7.8.9 without the auxiliary opening 12a, and the outer ring 22 are assembled into the base 2 in sequence.

In this state, the preload ring 18, the selected spacer 17
and the preload member 16 are temporarily assembled one after another, and the 12-piece port 1
5 to the protrusion 22a. Each auxiliary roller part 12a
The two wooden bins 14a and 14b are used to control each second reduction unit 11a.
Position each and temporarily assemble the two ports 13a.
, 13b. Thereafter, while rotating the outer ring 22, the twelve ports 15 are sequentially fully tightened, and a uniform pressing force is applied to the preload ring 18 for centering. Thereby, the sliding torque of the outer ring 22 is set to an appropriate torque.

Next, the operation of this embodiment will be explained.

When the drive motor 1 is started by a command from the CPU 34,
The sun roller 4 rotates, and each planetary roller 7, 8, 9 pressed against the sun roller 4 rotates by #rubbing drive. The rotation of each planetary roller 7.8.9 is caused by the friction drive of the preload ring 1.
8 to the outer ring 22, the outer ring 22 rotates at a low speed at a predetermined rotational speed, and stops after rotating by a predetermined rotation angle.

The reduction ratio at this time is 6 times the diameter of the sun roller 4, d2 the diameter of the first reduction part 10a of each planetary roller 7, 8, 9,
The diameter of the second reduction part 11a of each planetary roller 7.8.9 is d.
3. Letting the diameter of the outer ring 22 be d4, it can be expressed by the following formula.

In the planetary roller reducer, the rotation of the sun roller 4 is transmitted to the outer ring 22 via each planetary roller 7.8, 9 and the preload ring 18 by friction drive, so that the rotation of the sun roller 4 is transmitted to the outer ring 22 via each planetary roller 7.8, 9 and the preload ring 18 and outer ring 22 are unavoidable. However, in this embodiment, the rotation angle of the outer ring 22 is detected by the encoder 27 and the detected value is fed back, so by using the highly accurate encoder 27, the rotation angle of the outer ring 22 can be accurately controlled.

As a result, the influence of the slip does not pose a practical problem, and the outer ring 22 can be used in robot arms and the like that require high absolute positioning accuracy.

〔Effect of the invention〕

Since the present invention is configured as described above, it produces the effects described below.

In the invention described in claim 1, since the central shaft portion of each planetary roller is pressed against the sun roller by one preload ring, the number of parts is reduced, the structure is simplified, and centering is facilitated. Become. Furthermore, since a small-diameter preload ring can be used, the outer ring, that is, the exterior, is small. Furthermore, since the preload is obtained by reducing the diameter of the preload ring, a predetermined preload can be obtained even with a thin preload ring.

In the invention described in claim 2, the preload can be adjusted by changing the thickness of the spacer, and if a predetermined spacer is selected, the sliding torque of the outer ring can be set to an appropriate torque.

In the invention according to claim 3, a thin preload ring can be used.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an embodiment of the planetary roller reducer of the present invention, FIG. 2 is a sectional view taken along line A-A in FIG. 1, and FIG.
A) is a top view of the preload ring shown in FIGS. 1 and 2, FIG. 3(B) is a sectional view taken along line B-B in FIG. 3(A), and FIG. 3(C) is a top view of the preload ring shown in FIG. (A) is an enlarged view of the main part, Fig. 4 is an operating circuit diagram of this embodiment, Fig. 5 is a graph showing the relationship between preload amount and outer ring slipping torque in this embodiment, and Fig. 6 is of the conventional example. FIG. 7 is a sectional view of a main part of another conventional example. 1------ Drive motor (drive source), 1a------
-Output shaft, 1b--Coupling, 2-----Base, 2a''--Motor mounting flange, 3-----=
-Fixed base, 4-------Sun roller, 5----One bearing, 6a, 6b--One... Bearing, 7.8. 9+++-+++-planetary roller, 10a--
---1st reduction section, 11a--2nd reduction section, 12a--auxiliary roller section, 13a, 13b--port, 14a, L4b--pin, 15-m-bolt, 16-- ---Block preload member, 17--------Surface, 18-----, Preload ring, 18a---Slot, 19.20.21-One pillar, 22-m-Outer ring (output shaft ), 22a-one protrusion, 23-, ,,,, tapered surface, 24a, 24b-one bearing, 25-one axis, 26-+++-bearing, 27-to-encoder, 278-one position detection axis , 8-=----- Support stand, 9--- Support plate, 0--- Cover 1-- Support member, 2-- Coupling, 3-- ---Fixing member with shaft portion, 3a--Shaft portion, 4 +++ ---CPU, 5--Digital servo, 6--One rotation speed sensor. Patent applicant Canon Co., Ltd.

Claims (1)

[Claims] 1. A sun roller rotated by a drive source, and a plurality of rollers having a large diameter roller section at both ends of a small diameter shaft section, the large diameter roller section circumscribing the outer peripheral surface of the sun roller. a planetary roller; an outer ring having a protrusion having a tapered surface facing the shaft portions of the plurality of planetary rollers; and a slot formed therein and interposed between the plurality of planetary rollers and the protrusion. A planetary roller speed reducer comprising a preload ring and a preload member for pressing the preload ring against the tapered surface of the protrusion. 2. The planetary roller speed reducer according to claim 1, further comprising a preload adjustment mechanism comprising a bolt for fixing the preload member to the protrusion, and a spacer held between the preload member and the protrusion. 3. The planetary roller speed reducer according to claim 2, wherein the bolt of the preload adjustment mechanism is provided inside the outer diameter rotating surface of both large diameter roller portions of each planetary roller.