JPH0571591A - Planetary gear device - Google Patents

Abstract

PURPOSE:To prevent the reduction of the transmission precision due to the chattering and tilt of the first internal gear by press-fitting a plurality of balls between a pair of grooves, setting the grooves opposed each other, and allowing the urging power for separating or attaching the first and second internal gears in the axis line direction between the both. CONSTITUTION:On the inner peripheral surface of a cylinder part 43, a groove 62 which is twisted by the equal angle in the same direction to a groove 61, and the arrangement pitch of the groove 62 is allowed to accord with the arrangement pitch of the groove 61, and in the state where the first internal gear 41 is accommodated into the cylinder part 43, the grooves 61 and 62 are set oppositely. Further, a plurality of balls 60 are press-fitted between the grooves 61 and 62 which are opposed each other. Accordingly, in the accommodated state between the grooves, the ball is in the state pressed by the grooves. The first internal gear 41 is set to a screw pair state for the cylinder part 43, and the first internal gear 41 and the cylinder part 43 are put into rolling contact with the ball 60. When each sectional surface of the grooves 61 and 62 has a circular form, the ball is set into point contact in the bottom part of each groove.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a planetary gear device, and more particularly,
Each planetary gear is composed of a pair of gears arranged side by side so as to be relatively rotatable, and an internal gear meshing with the planetary gear is composed of an internal gear fixed to the casing and an internal gear screw-paired to the casing. The present invention relates to a planetary gear device of the type described above.

[0002]

2. Description of the Related Art A planetary gear device is used as a speed reducer or the like. This type of planetary gear device includes a sun gear, a plurality of planet gears that mesh with each other on the outer periphery of the sun gear, and an internal gear that meshes with the planet gears. Is usually composed of
The internal gear is formed on the inner peripheral surface of the casing.

Japanese Patent Application No. 3-173803 has already been proposed for a device using this planetary gear device as a speed reducer. This proposal makes it possible to prevent rattling due to backlash in a planetary gear type speed reducer,
The servomotor (M) can be directly connected to the speed reducer, and the configuration shown in FIGS. 1 and 2 is adopted. In other words, the planetary gears (2) and (2) that mesh with the sun gear (1) are supported by the disc (31) integrated with the output shaft (3),
Each planetary gear (2) has a configuration in which a first gear (21) and a second gear (22) that rotate separately are arranged side by side, and the internal gear (40) formed on the inner peripheral surface of the casing (4) is A first internal gear (41) that meshes with the first gears (21) (21) and a second internal gear (42) that meshes with the second gears (22) (22) (42) is integrated with the casing (4) and the other first internal gear
(41) has a structure in which its outer peripheral surface is screw-paired with the inner peripheral surface of the casing (4), and these internal gears are urged by a compression spring (46) in a direction toward or away from each other.

In this prior art, the sun gear (1) →
Two paths: the first gear (21) → the first transmission system of the first internal gear (41) and the sun gear (1) → the second gear (22) → the second transmission system of the second internal gear (42) Therefore, the torque is transmitted. Moreover, the screw pair action of the casing (4) and the first internal gear (41), and the first
A relative rotational force acts between the first internal gear (41) and the second internal gear (42) by the axial urging force acting on the internal gear (41). Therefore, due to this relative rotational force, the teeth of the first gear (21) and the first internal gear (41), and the second gear (22) and the second internal gear
A gap in the circumferential direction occurs between the teeth of (42). on the other hand,
Since the first gear (21) and the second gear (22) are both meshed with the sun gear (1), this circumferential deviation is the sun gear.
Backlash between (1) and planet gears (2) and planet gears
It is the sum of the backlash between (2) and the internal gear (40). That is, the sun gear (1) and the planetary gear (2) are meshed with each other, and the planetary gear (2) and the internal gear (40) are meshed with each other without any backlash. Therefore, the transmission accuracy in which the sun gear (1), the planetary gear (2), and the internal gear (40) are intermeshed with each other is improved, and a quiet transmission state is obtained. Even if the teeth of each meshing part are worn and the backlash of this meshing part is expanded, relative rotational force is always applied between the first internal gear (41) and the second internal gear (42). Therefore, it is set to a new meshing state where this backlash has been eliminated.

However, in the prior art, the first
Since the internal gear (41) has a thin annular shape,
The outer peripheral surface of (41) and the inner peripheral surface of the casing (4) are of a type in which the twist splines (S) are engaged with each other by screw engagement as shown in FIG. In terms of transmission accuracy, it was a little insufficient now. The twist spline (S) is formed by twisting the groove of the spline so that it is twisted at a certain angle with respect to the axis of the first internal gear (41). This is because the first internal gear (41) has rattling corresponding to this fitting margin. Further, since the width of the first internal gear (41) in the axial direction is small and the diameter thereof is large, the first internal gear (41) easily tilts when it is moved along the torsion spline (S).

According to the present invention, "each planetary gear (2) is a sun gear.
(1) is composed of a first gear (21) and a second gear (22) that mesh with each other, and an internal gear (40) has a first internal gear (41) and a first gear that mesh with the first gear (21). A second internal gear (42) meshing with two gears (22), fixing the second internal gear (42) to the casing (4), and at the same time, providing a first internal gear (41) and a second internal gear.
In the planetary gear device in which a biasing force in the relative rotational direction is applied between (42), it is possible to prevent a reduction in transmission accuracy due to rattling or tilting of the first internal gear (41), and to enable quieter transmission. The task is to [Invention of Claim 1]

[0007]

[Technical Means] A technical means of the present invention for solving the above-mentioned problem is to form a tubular portion (43) for accommodating a first internal gear (41) in a casing (4), and On the inner peripheral surface of 43) and the outer peripheral surface of the first internal gear (41), a plurality of grooves (61) (61) and grooves (62) (62) twisted in the same direction with respect to these axes at a constant angle. And the grooves (61) and (62) are opposed to each other to form a pair of grooves (6
1) Inner gear by inserting multiple balls (60) (60) between (62)
A biasing force is applied between the (41) and the second internal gear (42) to separate or approach them in the axial direction. "

[0008]

The above technical means operates as follows. Each groove (6
Since the 1) and the groove (62) are both twisted in the same direction, the first internal gear (41) and the tubular portion (43) are separated from each other by the balls (60) (6).
Pair with screws through 0). Then, since a biasing force is applied between the first internal gear (41) and the second internal gear (42) to separate or approach them in the axial direction, the first internal gear (41) and the second internal gear (42 ) And the urging force in the relative rotation direction is always applied to the shaft, and the power is transmitted in a state where backlash does not occur as in the conventional case.

Further, the screw pair mechanism of the cylindrical portion (43) and the first internal gear (41) has a state in which the balls (60) and (60) are press-fitted between the grooves (61) and (62). Therefore, there is no fitting margin in the screw pair mechanism portion. When the first internal gear (41) moves (twisted) while rotating in the axial direction by the action of the screw pair mechanism portion, the first internal gear (41) and the tubular portion (43) move to the ball (6
Since it will move in a rolling contact state via 0) and (60), it will twist and move with a light biasing force. That is, the first internal gear
The (41) smoothly twists while rollingly contacting the tubular portion (43) via the balls (60) and (60). Further, since the ball press-fitting portions are formed at a plurality of locations on the outer circumference of the first internal gear (41), when the balls are twisted by the biasing force applied to the first internal gear (41), each ball is moved. The rolling movement amount of each ball in the press-fitting portion becomes constant, and the first internal gear (41) is unlikely to be inclined with respect to the axis.

[0010]

[Effect] Since there is no fitting margin between the cylindrical portion (43) and the first internal gear (41) in the screw pair mechanism portion, the first internal gear (41) is inclined with respect to the axis. Since it is difficult, rattling and reduction in transmission accuracy caused by these do not occur. Since the rolling contact portions of the first internal gear (41) and the tubular portion (43) and the balls (60) and (60) move smoothly by twisting, when a tooth of each gear is worn, a new back The transition to the rush elimination state is smooth. [Invention of Claim 2] This invention solves the same problem as that of the invention of Claim 1, and
The object is to solve the problems by making the internal gear (41) in a rotating pair with respect to the casing (4) or the first internal gear (41) without screwing the internal gear (41) to the casing (4). ..

[0011]

[Technical Means] The technical means of the present invention for solving the above-mentioned problem is to "fix the second internal gear (42) to the casing (4) and the first internal gear (41) to the casing (4). Alternatively, the wedge is rotatably paired with the second internal gear (42) and is urged in the axial direction between the casing (4) or the second internal gear (42) and the first internal gear (41). The body (6) is interposed, and the first internal gear (41) is rotated relative to the second internal gear (42) by the axial movement of the wedge body (6). "

[0012]

The above technical means operates as follows. Between the casing (4) or the second internal gear (42) and the first internal gear (41), a wedge body (6) biased in the axial direction is interposed,
Since the first internal gear (41) is rotated relative to the second internal gear (42) by the axial movement of the wedge body (6),
A biasing force in the relative rotational direction is constantly applied between the first internal gear (41) and the second internal gear (42), and the transmission is performed in the state where backlash does not occur as in the conventional case.

Further, the first internal gear (41) is rotated and paired with the casing (4) or the second internal gear (42) to obtain the first internal gear (41).
Between (41) and the casing (4) or the second internal gear (42),
No rattling occurs and the first internal gear (41) is not inclined with respect to the axis.

[0014]

[Effect] There is no backlash between the first internal gear (41) and the casing (4) or the second internal gear (42), and the first internal gear (41) is inclined with respect to the axis. Therefore, there is no rattling during transmission or reduction in transmission accuracy.

[0015]

Embodiments of the present invention described above will now be described in detail with reference to the drawings. [Embodiment 1] This embodiment has a structure similar to that of the above-mentioned conventional example, and the present invention is applied to a speed reducer of a type directly connected to a servo motor (M).

In this case, as shown in FIG. 3, the sun gear
(1) is directly attached to the output shaft (J) of the servomotor (M), and the casing (4) is directly attached to the servomotor (M). Therefore, the casing (4) is a cylinder body that opens to one side, and the servo motor (M) is fixed to the open end by screwing. On the other hand, the output shaft (3) projects from the closed end surface of the casing (4), and a disc (31) is integrally connected to the inner end of the output shaft (3). The planetary gear (2) is rotatably mounted on the four mounting shafts (5) (5) provided on the disc (31). The planetary gears (2) are composed of a first gear (21) and a second gear (22) that rotate independently of each other, and these planetary gears are arranged side by side on a common mounting shaft (5). ..

The inner periphery of the casing (4) has the planetary gears.
(2) A second internal gear (42) that meshes with the second gears (22) and (22) of (2) is formed, and a tubular portion (following the formation portion of the first internal gear (41) ( 43) accommodates the first internal gear (41), the first internal gear (41) is the first gear (21) (21), and the second internal gear (42) is the second gear (22) (22). Mesh with. As shown in the figure, the first internal gear (41) has a plurality of hole portions which are open to one end surface in the annular body.
(45) (45) is formed with a predetermined pitch, and teeth are formed on the inner circumference of this annular body. On the outer peripheral surface of the annular body, as shown in FIG. (61) (61) is formed. The axis of this groove (61) is, as shown in FIG.
The first internal gear (41) is formed in a twisted manner so as to be inclined at a constant angle (5 to 15 degrees, preferably 8 to 12 degrees) with respect to the axis (generic line of the outer peripheral surface thereof), and Its cross section is arcuate or V-shaped.

Grooves (62) and (62) that are twisted in the same direction and at the same angle as the groove (61) are formed on the inner peripheral surface of the cylindrical portion (43), and the cross section of the groove (62) is also the same. It is formed in an arc shape or a V shape. Then, the arrangement pitch of the grooves (62) (62) is set to the grooves (61) (61).
The groove (61) and the groove (62) face each other when the first internal gear (41) is housed in the tubular portion (43). A plurality of balls (60) (60) are press-fitted between the grooves (61) and the groove (62) facing each other. That is, in the state of being housed between the grooves, each ball is in a state of being pressed by the grooves. The first internal gear (41) is paired with the cylindrical portion (43) by a screw, and the first internal gear (41) and the cylindrical portion are
Together with (43), the balls (60) and (60) come into rolling contact. Here, when the cross sections of the grooves (61) and (62) are arcs, the curvature of this cross section is set to be smaller than the curvature of the balls (60). Therefore, the balls make point contact at the valleys of the grooves.

The axial width of the tubular portion (43) is set larger than that of the first internal gear (41), and the first internal gear (41) is within the range of the difference between the widths of the first internal gear (41). Can be moved in the axial direction. The end face (44) of the formation portion of the second internal gear (42) and the hole (4
A compression spring (46) is interposed between the bottom portion of 5) and the first internal gear (41) to apply an axial biasing force.

In this embodiment, since the first internal gear (41) is urged in the direction away from the end face (44), the end face (44) is initially attached as shown in FIG. The first internal gear (41) is incorporated so that a constant gap is formed between the end surface (47) on the side opposite to (4) and the end surface of the first internal gear (41).
In addition, the above-mentioned gap is the screw pair of the first internal gear (41) and the tubular portion (43) with respect to the total amount of backlash when the sun gear (1), the planetary gear (2) and the casing (4) are engaged. It is determined by the twist angle of the portion and the separation distance from the end surface (44) of the first internal gear (41). Here, when the first internal gear (41) is in contact with the end surface (44), the groove (61) is formed so that the tooth trace of the first internal gear (41) and that of the second internal gear (42) match. ) And groove (6
2) is formed.

In this embodiment, as shown in FIG. 3, the output shaft (J) of the servomotor (M) is fastened to the sun gear (1) in a transmission state by using the key (13) and the tightening nut (N). Then, when the body of the servo motor (M) is fixed to the open end of the casing (4), the rotation speed of the output shaft (3) will be
It will be slowed down from that of (J). Then, the first internal gear (41) and the cylinder portion (43) are formed by a large number of screw pair mechanism portions in which a plurality of balls (60) (60) are interposed between the groove (61) and the groove (62). , The screw pairs are mutually paired, and the biasing force of the compression spring (46) housed in the hole (45) causes relative rotation between the first internal gear (41) and the second internal gear (42). Since the power always acts, it is possible to perform transmission without backlash due to the above-described action. Further, the action of the screw pair mechanism portion causes the first
The internal gear (41) twists and moves without tilting.

[Embodiment 2] This Embodiment 2 corresponds to the invention of Claim 2 and, as shown in FIG. 6, as shown in FIG.
The sun gear (1) is directly installed on the sun gear, and a plurality of planetary gears (2) and (2) are meshed with the sun gear (1). Each planetary gear (2) is composed of a first gear (21) and a second gear (22), and these planetary gears (2) are internal gears that mesh with the outer periphery of the planetary gears (2).
The reference numeral (40) includes a second internal gear (42) integrated with the casing (4) and a separate first internal gear (41).

In this embodiment, the casing (4) comprises a casing half (4a) that rotatably supports the input shaft (10) and a casing half (4b) that rotatably supports the output shaft (3). ) And
Both open ends are screwed together to form a hermetically sealed state. A second internal gear (42) is integrally formed on the inner peripheral surface of the body of one casing half (4a), and a second internal gear is formed at the open end of the other casing half (4b). (Four
2) is attached in a paired state. In order to realize this pair around the open end of the casing half (4b),
An annular groove (63) that opens to the open end side and the inner peripheral side is formed,
The axial groove width of the annular groove (63) is made substantially equal to the thickness of the first internal gear (41), and the diameter of the annular groove (63) is made to coincide with the outer diameter of the first internal gear (41). ing. Therefore, the first internal gear (41) interposed between the coupling end faces of the casing half body (4a) and the casing half body (4b) in a coupled state.
Will be paired around the casing (4).

As shown in FIGS. 7 and 8, the outer peripheral portion of the first internal gear (41) is provided with a plurality of notch portions which are open to the outer peripheral side.
(7) (7) is formed, and one end face in the circumferential direction of the first internal gear (41) in each notch (7) is an inclined surface (inclined with respect to the generatrix of the first internal gear). 71). A wedge body (6) is inserted into each notch (7). Each of these wedge bodies (6) and (6) protrudes from the one end of the support ring (64) in the same direction, and each wedge body (6) extends in the circumferential direction of the support ring (64) as shown in FIG. One side surface of the wedge ring is an inclined surface (65) inclined to the generatrix of the support ring (64).
A shaft portion (66) projects from the tip of (6). The wedge body (6)
The arrangement position of (6) is the cutout portion (7) on the outer periphery of the first internal gear (41).
It is made to match that of (7), and the inclination angle of the inclined surface (65) is made to coincide with that of the inclined surface (71). Further, a plurality of holes (48) (48) for inserting the shaft portions (66) (66) of the wedge body (6) are formed on the end surface of the casing half body (4a). Make the diameter of the shaft (66) approximately the same as that of the shaft (66).
Wedge (6) with the array position of 8) protruding from the support ring (64)
It is made to match that of the shaft part (66) (66) of (6). The width of the notch (7) in the circumferential direction is set larger than that of the wedge (6).

Therefore, as shown in FIG. 6, the wedge bodies (6) and (6) are assembled in the notches (7) and (7) so as to be housed separately, and the inclined surface (71) is formed.
And the inclined surface (65) are contacted with each other, and a plurality of compression springs (46) (46) are interposed between the support ring (64) and the casing half body (4b), the same as in the first embodiment. To function. This will be explained below. In this one, multiple wedges
(6) Since the shaft portion (66) (66) of the support ring (64) equipped with (6) is individually fitted into the plurality of holes (48) (48), the support ring (64) And the casing half body (4a) are in the even pair state. Then, each wedge (6) and each inclined surface (7) of the notch (7)
Since 1) is in contact with the inclined surface (65) and the inclined surface (71), when the whole of the support ring (64) moves in the axial direction, the first surface is contacted with each other in accordance with the contact between the inclined surfaces. The internal gear (41) is rotated. That is, the first internal gear (41) is provided with the biasing force in the relative rotational direction with respect to the second internal gear (42) by the biasing force of the compression spring (46), and the backlash elimination action described above is achieved. Occurs. The inclination angle of the inclined surface (65) and the inclined surface (71) with respect to the generatrix of the support ring (64) and the first internal gear (41) is 5
The degree is set to about 15 degrees, preferably 8 degrees to 12 degrees.

In this embodiment, a plurality of wedge bodies (6) and (6) are integrally connected to the support ring (64), but the wedge bodies (6) and (6) are separated, A configuration may be adopted in which these are separately biased in the axial direction. In short, the wedge body (6) and the first internal gear
It suffices that a part of (41) constitutes a linear cam mechanism and a rotational force is applied to the first internal gear (41) by the direct movement of the wedge body (6).

[Brief description of drawings]

FIG. 1 is a sectional view of a speed reducer of the previous application.

FIG. 2 is a sectional view taken along line XX.

FIG. 3 is a sectional view of an embodiment of the invention of claim 1.

FIG. 4 is a sectional view taken along line YY of FIG.

FIG. 5 is a partially enlarged plan view of the first internal gear (41).

FIG. 6 is a sectional view of an embodiment of the invention of claim 2;

FIG. 7 is an exploded plan view of the support ring (64) and the first internal gear (41).

FIG. 8 is a sectional view taken along line ZZ.

[Explanation of sign]

 (2) ・ ・ ・ Planetary gear (4) ・ ・ ・ Casing (1) ・ ・ ・ Sun gear (43) ・ ・ ・ Cylindrical part (21) ・ ・ ・ First gear (61) ・ ・ ・ Groove (22)・ ・ ・ Second gear (62) ・ ・ ・ Groove (40) ・ ・ ・ Internal gear (43) ・ ・ ・ Cylinder (41) ・ ・ ・ First internal gear (60) ・ ・ ・ Ball (42) ・..Second internal gear

Claims (2)

[Claims] 1. A planetary gear (2) is composed of a first gear (21) and a second gear (22) that mesh together with a sun gear (1), and an internal gear (40) is the first gear. The first internal gear (4
1) and a second internal gear (42) that meshes with the second gear (22). The second internal gear (42) is fixed to the casing (4) and the first internal gear (41) In a planetary gear device in which a biasing force in the relative rotation direction is applied between the second internal gear (42), a cylindrical portion for housing the first internal gear (41) in the casing (4).
(43) is formed, and the inner peripheral surface of the tubular portion (43) and the first internal gear (41)
A plurality of grooves (61) (61) and grooves (62) (62) twisted at a constant angle with respect to these axes are formed on the outer peripheral surface of the groove (61) (62).
And a plurality of balls (60) (60) are press-fitted between the pair of grooves (61) (62) so that the first internal gear (41) and the second internal gear
A planetary gear device in which an urging force that causes the two to separate or approach each other in the axial direction is applied between (42). 2. Each planetary gear (2) comprises a first gear (21) and a second gear (22) which mesh with a sun gear (1), and an internal gear (40) is the first gear (21). 1st internal gear (41) meshing with 21)
And a second internal gear (42) meshing with the second gear (22). The second internal gear (42) is fixed to the casing (4) and the first internal gear (41) and the second internal gear (42) are provided. In a planetary gear device in which a biasing force in the relative rotation direction is applied between the internal gears (42),
The first internal gear (41) is rotated and paired with the casing (4) or the second internal gear (42) to form the casing (4) or the second internal gear (4).
A wedge body (6) biased in the axial direction is interposed between the second internal gear (41) and the second internal gear (41), and the first internal gear (41) is moved by the axial movement of the wedge body (6). ) Is relatively rotated with respect to the second internal gear (42).