JPH0570015B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a transmission device used in a control device such as an industrial robot whose rotation direction is switched between forward and reverse during operation.

[Prior art]

In control equipment such as industrial robots, the direction of rotation is not limited to only one direction, but is operated while being switched between forward and reverse directions at any time. On the other hand, gears in transmissions installed in such control devices always have backlash, and because of this backlash, each time the direction of rotation is switched between forward and reverse, the amount of rotation is delayed by the amount of backlash, resulting in inaccurate transmission. This problem has been pointed out.

Conventionally, in order to eliminate the inaccuracy of transmission due to such backlash, a mechanism has been proposed in which gears are stacked double, the phase is shifted by the amount of backlash, and the two tooth surfaces mesh with each other with 0 backlash. . However, since errors inevitably occur in the backlash due to machining, fixing the two gears to the shaft with a phase shift by the amount of the backlash with such a minute error will impede the indexing accuracy in the workmanship. This is extremely difficult from above.
Furthermore, since the teeth are in mesh with each other, the inevitable wedge effect that will occur is inevitable, making smooth operation difficult.

[Purpose of the invention]

An object of the present invention is to prevent a delay due to backlash from occurring when switching between forward and reverse directions of power rotation.
It is an object of the present invention to provide a control transmission which utilizes the above-described structure and which does not cause the above-mentioned wedge effect and enables smooth operation due to its extremely simple structure.

[Structure of the invention]

A control transmission of the present invention that achieves the above object is a planetary gear in which two pairs of intermediate gears are interposed between a sun gear and an internal gear, and an intermediate shaft supporting these two pairs of intermediate gears is fixed to a carrier. Consisting of a mechanism,
In this planetary mechanism, one pair of intermediate shafts is fixed on one line segment L with respect to line segments L and L' that are orthogonal to each other at the axis Os of the sun gear. At the same time, the other pair of intermediate shafts is fixed at an indexed position offset by a distance δ in the circumferential direction from the other line segment L', and by fixing the position of the intermediate shafts, one pair of intermediate gears is aligned with the sun. The tooth contact that meshes with the gear and internal gear,
The other intermediate gear is characterized in that the sun gear and the tooth abutment meshing with the internal gear are in a meshing state where power is transmitted in opposite rotational directions.

The two pairs of intermediate shafts fixed to the carrier in this way are fixed on line segments L and L' perpendicular to the axis of the sun gear, one pair is fixed on line segment L, while the other pair is fixed on line segment L, while the other pair is By simply assembling the gears at an indexed position offset by a distance δ in the circumferential direction from the line segment L', the gear train of one pair of intermediate gears is a tooth contact that transmits power only in the forward rotation direction. The gear train of the other pair of intermediate gears can have teeth that transmit power only in the reverse rotation direction. Therefore, due to this meshing state, when the direction of rotation is switched between forward and reverse, there is no rotation delay equivalent to backlash, and there is no wedge effect, making it possible to transmit power smoothly and accurately. It will become.

Furthermore, in the control transmission of the present invention, when supporting the intermediate gear on the intermediate shaft, a ring is rotatably mounted on the intermediate shaft via a bearing,
Since the intermediate gear is supported so that it can rotate together with a play that can form an oil film in the ring, errors in machining the gear can be absorbed by the structure that includes the play that can form an oil film, resulting in even more accurate processing. enables efficient power transmission.

The present invention will be specifically explained below using examples shown in the drawings.

1 to 3 show an example of a control transmission according to the present invention.

In these figures, 1 is an input shaft, 2 is an output shaft, and 3 is a casing. In this embodiment, the casing 3 is separated into a bracket 3a on the input shaft side and a bracket 3b on the output shaft side, and the internal gear 7 is fixed between them. Input shaft 1
is rotatably supported by the bearing part 4 of the bracket 3a, and the output shaft 2 is supported by the bearing part 6 of the bracket 3b.
is rotatably supported. A sun gear 5 is fixed to the inner end of the input shaft 1, and between the sun gear 5 and the internal gear 7, two pairs of intermediate gears 8a, 8a;
b and 8b are engaged.

The two pairs of intermediate gears 8a, 8a; 8b, 8b
are the intermediate shafts 9 fixed to the carriers 16, respectively.
It is supported by a, 9a; 9b, 9b. Each of the intermediate shafts 9a, 9a; 9b, 9b rotatably supports a ring 13 via a bearing 10, and the intermediate gears 8a, 8 are mounted on the ring 13.
a; 8b, 8b are small gaps 14 where oil film can be formed
are supported so that they rotate together. In the figure, the play gap 14 is exaggerated and shown in a large size for easy understanding, but in reality it is an extremely small gap that is optimal for the generation of an oil film.

FIG. 3 is an enlarged view of the main part of the planetary gear mechanism, and L and L' in the figure are two line segments that are orthogonal to each other at the axis Os of the sun gear 5. intermediate gear 8
Axial center Oa of intermediate shafts 9a, 9a supporting a, 8a
is arranged on the line segment L across the axis of the sun gear 5 and is fixed on the carrier 16. On the other hand, the axes Ob of the intermediate shafts 9b, 9b that support the other intermediate gears 8b, 8b are not fixed above the line segment L', and the backlash of the gears is moved in the circumferential direction from this line segment L'. It is fixed at a position offset by a distance δ determined from .

By fixing the intermediate shafts 9a and 9b on the carrier 16 in a positional relationship determined by the distance δ in this way, the intermediate gears 8a and 8a can rotate the tooth surface against the rotation of the sun gear 5 in the counterclockwise direction R'. The other intermediate gears 8b and 8b are in a meshing state in which their tooth surfaces are in contact with each other when rotated in the clockwise direction R, which is opposite to the above. That is, the intermediate gear 8a contacts the sun gear 5 and the internal gear 7 at points C and A, and also contacts the ring 13 at a point B in an eccentric state, and the intermediate gear 8b contacts the sun gear 5 and the internal gear 7. The ring 13 contacts the ring 13 at points D and F, and also contacts the ring 13 at a point E in an eccentric state.

The assembled state of gears in this meshing relationship is as follows:
The assembly can be easily performed by first assembling the intermediate gear 8a with the sun gear 5 in a meshing state as shown in FIG. 3, and then assembling the intermediate gear 8b.

Now, in the transmission set in the meshing state described above, the input shaft 1 is rotated clockwise R' (forward rotation direction).
When rotating, the power is decelerated and transmitted to the output shaft 2 via the gear train of the intermediate gear 8b, but at this time, the power is transmitted to the output shaft 2 via the gear train of the other intermediate gear 8a.
No power is transmitted to the That is, when rotating in the clockwise direction R', the meshing state of the intermediate gear 8a with the gear example is such that there is a gap c in the rotation direction, so no power is transmitted, and the tooth surface on the opposite side is engaged with the intermediate gear 8a. Simply make contact at points A and C and follow the rotation.

In contrast, input shaft 1 is rotated counterclockwise R (reverse direction)
In this case, contrary to the case of normal rotation, the power is decelerated and transmitted to the output shaft 2 through the other intermediate gear 8a, and is not transmitted to the output shaft 2 through the gear train of the intermediate gear 8b. . That is, the tooth contact state of the gear train of the intermediate gear 8b at the time of this reverse rotation R is a state in which a gap c' is interposed in the rotation direction, and
The tooth flanks on the opposite side are simply brought into contact at points D and F and rotated accordingly.

In this way, the gear train on the side that does not transmit power maintains tooth surface contact and follows the rotation, so when the rotation switches from the forward direction R' to the reverse direction R, and from the reverse direction R to the forward direction R' At the moment of this switching, the gear train side that was following in the above-mentioned contact state immediately performs a power transmission action. Therefore, the rotational direction is switched with virtually no backlash, and accurate transmission without rotational delay can be achieved.

Furthermore, as in the above-mentioned embodiment, the intermediate gear is not supported directly on the intermediate shaft;
By interposing a ring 13 rotatably supported through a bearing 10 and supporting this ring 13 through a small clearance 14 that allows oil film formation, the influence of gear machining errors can be reduced and the process can be further improved. Accurate transmission can be achieved.

That is, when the intermediate gears are supported directly on the intermediate shaft without intervening the ring 13, the meshing state is at points A and C for the gear train of one intermediate gear 8a, and at point D for the gear train of the other intermediate gear 8b. Only F. Therefore, in this configuration, the effects of errors such as gear pitch, tooth profile, eccentricity, etc. on rotation are sensitive. However, if the ring 13 is used to interpose the points B and E, which are made of rolling contact between circular arcs, as described above, the intermediate gear is allowed to move slightly in the radial direction as shown by the arrow Q. Therefore, the influence on the rotation caused by the error of the gear as described above can be avoided.

In addition, by providing a play gap 14 that forms an oil film between the intermediate gear and the ring, the ring and intermediate gear rotate together, so the Sommerfeld number of the bearing theory is twice that of a normal one. Become,
The generation of the oil film becomes more effective in avoiding errors.

Furthermore, the present invention has an extremely simple structure because the above-described two pairs of intermediate gears are meshed with each other in different rotational directions, simply by determining the fixing position of the intermediate shaft relative to the carrier. , thereby reducing manufacturing costs.

In addition, in the planetary gear mechanism of the above-mentioned embodiment, the internal gear is fixed to the casing and the carrier supporting the intermediate gear rotates, but in the present invention, the internal gear is configured to rotate integrally with the output shaft. The invention is also applicable to a so-called star-type planetary gear mechanism in which the intermediate shaft of the intermediate gear is fixed to the casing.

Further, in the above embodiment, the case of a speed reduction device was illustrated, but it can be applied as a speed increase device by inputting from the output shaft side and outputting from the input shaft side.

〔Effect of the invention〕

As described above, according to the control transmission of the present invention, in a planetary gear mechanism provided with two pairs of intermediate gears, when fixing the two pairs of intermediate shafts supporting the two pairs of intermediate gears to the carrier, the sun gear For line segments L and L' that are perpendicular to each other at the axis of , one pair is line segment L
The gear train of one pair of intermediate gears can be fixed in the correct position by an extremely simple assembly of fixing the other pair at an index position offset by a distance δ in the circumferential direction from the line segment L'. The gear train of the other pair of intermediate gears can be a tooth contact that transmits power only in the rotational direction, and the gear train of the other pair of intermediate gears can be a tooth contact that transmits power only in the reverse rotation direction. Due to this meshing condition between the teeth, when the direction of rotation is switched between forward and reverse, smooth and accurate power is generated without any rotational delay equivalent to the backlash or wedge effect. enable transmission.

Furthermore, the control transmission of the present invention has a structure in which a ring is rotatably mounted on the intermediate shaft via a bearing as a structure supported on the intermediate shaft of the intermediate gear, and a loose ring capable of forming an oil film is interposed in the ring. Since the intermediate gear is supported so as to be rotatable together, the structure including the play that allows the formation of an oil film absorbs transmission errors due to machining errors of the gear, and enables more accurate power transmission.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a control transmission according to an embodiment of the present invention, FIG. 2 is a diagram showing the principle of the present invention shown in the direction of the - arrow in FIG. 1, and FIG. 3 is an enlarged view of the main parts of the same device. be. 1...Input shaft, 2...Output shaft, 5...Sun gear, 7...
Internal gear, 8a, 8b... intermediate gear, 9a, 9b... intermediate shaft, 10... bearing, 13... ring, 14...
Playtime, 16...carrier.

Claims (1)

[Claims] 1. Two pairs of intermediate gears 8a, 8a; 8b, 8b are interposed between the sun gear 5 and the internal gear 7, and these two pairs of intermediate gears 8a, 8a; 8b, 8b are supported. It consists of a planetary gear mechanism in which intermediate shafts 9a, 9a; 9b, 9b are fixed to a carrier 16, and the fixed position of the intermediate shafts 9a, 9a; 9b, 9b with respect to the carrier 16 is aligned with the axis of the sun gear 5.
With respect to line segments L and L' that are orthogonal to each other at Os, one pair of intermediate axes 9a and 9a are fixed on one line segment L, and the other pair of intermediate axes 9b and 9b are fixed on the other line segment L. The intermediate shafts 9a,
By fixing the positions of 9a; 9b, 9b, one pair of intermediate gears 8a, 8a is brought into contact with the sun gear 5 and internal gear 7, and the other intermediate gears 8b, 8b are brought into contact with the sun gear 5 and internal gear 7. A ring 13 is rotatably attached to the intermediate shafts 9a, 9a; 9b, 9b via bearings 10, and a ring 13 is rotatably mounted on the intermediate shafts 9a, 9a; 9b, 9b through bearings 10. A control transmission which is driven by forward/reverse switching and supports the intermediate gears 8a, 8a; 8b, 8b so as to rotate together with an oil film-formable slacker 14 interposed therebetween.