JP7136827B2 - transmission device - Google Patents

Description

The present invention relates to transmissions.

2. Description of the Related Art Conventionally, a speed reducer that reduces the rotation speed of an output shaft of a motor for output is known as a transmission device that transmits transmitted power. Generally, a speed reducer reduces the rotation speed of an output shaft by using a plurality of gears, and is capable of outputting torque inversely proportional to the speed reduction. As a reduction gear of this type, for example, Patent Document 1 below discloses a reduction gear using an external gear that rotates eccentrically with rotation of an input shaft.

The speed reducer described in Patent Document 1 includes an input shaft, an eccentric body that rotates as the input shaft rotates, an external gear that is attached to the eccentric body and can rotate eccentrically, and an external gear that is fixed to a casing. It has an internal gear that meshes internally, and an output shaft that is connected to the external gear via spline means that extracts and transmits only the rotation component of the external gear.
The external gear is arranged inside the internal gear while meshing with the internal gear, and is rotatable about an eccentric axis eccentric to the central axis of the internal gear. The number of teeth of the external gear is one less than the number of teeth of the internal gear.

According to the speed reducer described in Patent Document 1, when the input shaft rotates, the rotational force is transmitted to the external gear via the eccentric body. Since the rotation of the external gear is restrained by meshing with the internal gear, the external gear rotates eccentrically so as to oscillate about the eccentric axis while being inscribed with the internal gear. At this time, the external gear rotates eccentrically while being decelerated by the relationship between the number of teeth of the external gear and the number of teeth of the internal gear. Since only the rotation component of the external gear can be extracted by the spline means and transmitted to the output shaft, the output shaft can be rotated in a decelerated state.

Japanese Patent No. 2686337

However, in the conventional speed reducer described above, the external gear arranged inside the internal gear fixed to the casing is rotated eccentrically so as to oscillate. It is necessary to provide spline means or the like for extracting only the rotation component of the external gear between them. Therefore, a space is required for providing the spline means, etc., and it is difficult to reduce the size and thickness of the speed reducer. Moreover, the provision of the spline means or the like complicates the structure and increases the number of parts.

SUMMARY OF THE INVENTION The present invention has been made in consideration of such circumstances, and its object is to provide a transmission device that can be easily reduced in size and thickness, and that can lead to cost reduction and improvement in maintainability. That is.

(1) A transmission device according to the present invention includes an input shaft that rotates about an axis by transmitted power, and an eccentric axis that is eccentric to the axis, and is arranged along with the rotation of the input shaft. an internal gear having a plurality of circumferentially-spaced internal teeth operative and orbiting about the eccentric axis; and positioned to face the internal gear on one axial side of the internal gear. and an external gear having a plurality of external teeth that are arranged rotatably around the axis and can mesh with the plurality of internal teeth; and an output shaft that rotates around the axis as the external gear rotates. and is fixed to a fixed plate arranged to face the internal gear on the other side in the axial direction, and constrains the rotation of the internal gear so as to eccentrically oscillate about the axis. a guide member for guiding an internal gear, wherein the external teeth have a number of teeth different from the number of teeth of the internal teeth; the internal gear is provided with the internal teeth; a gear body enclosing it from the outside; an internal gear plate disposed so as to face the fixed plate and having the gear body formed on the outer peripheral edge side; a housing recess formed in a plate, wherein the guide member includes a guide portion that is disposed in the housing recess and can be in contact with an inner wall surface of the housing recess; It is arranged in the housing recess so as to be eccentric with respect to the center line of the housing recess by an amount of eccentricity between the axis and the eccentric axis .

According to the transmission device of the present invention, when the input shaft is rotated about the axis by the transmitted power, the internal gear behaves eccentrically about the axis along with the rotation of the input shaft. However, the rotation of the internal gear is restrained by the guide member fixed by the fixing plate, so that the internal gear can be guided from eccentric rotation about the axis to eccentric oscillation about the axis. The behavior of the internal gear can be controlled. As a result, the internal gear can be eccentrically oscillated with respect to the external gear so that the internal teeth sequentially get over the external teeth in the circumferential direction while the external teeth are inscribed in the internal teeth. Therefore, every time the internal teeth get over the external teeth due to the eccentric oscillation of the internal gear, the external teeth can be pressed in the circumferential direction via the internal teeth, and the external gear and the output shaft can be rotated around the axis. can be done.

In this way, by transmitting the power transmitted to the input shaft to the internal gear, the internal gear is caused to eccentrically oscillate, thereby pressing the external teeth in the circumferential direction via the internal teeth, thereby transmitting the power to the external gear. can be done. As a result, the external gear and the output shaft can be rotated around the axis. In particular, since the number of teeth of the external teeth and the number of teeth of the internal teeth are different, it is possible to decelerate or accelerate the external gear by the angular difference in the number of teeth. As a result, the output shaft can be rotated while being decelerated or accelerated with respect to the rotation of the input shaft.

Further, unlike conventional reduction gears and the like, the internal gear side is eccentrically oscillated, so that the external gear can be rotated about its axis in a simple rotational motion. Therefore, it is not necessary to take out only the rotation component of the external gear, for example, and power can be transmitted directly from the external gear to the output shaft to rotate the output shaft about its axis. Therefore, it is possible to achieve a simple structure with a reduced number of parts, and it is possible to reduce the size and thickness of the transmission device as a whole. In addition, it can lead to cost reduction and improvement of maintainability.

Further, the guide portion arranged in the accommodation recess is eccentric with respect to the center line of the accommodation recess by the amount of eccentricity between the axis and the eccentric axis. Therefore, even if the internal gear behaves eccentrically as it rotates with the rotation of the input shaft, the inner wall surface of the accommodating recess abuts against the guide portion, so that the rotation of the internal gear can be properly restrained. . In addition, the internal gear can be eccentrically oscillated while the guide portion is inscribed with the inner wall surface of the accommodation recess. Therefore, while guiding the movement of the internal gear using the guide portion, the internal gear can be eccentrically oscillated as if eccentrically rotated around the guide portion.
In this way, since the guide portion can be used to guide the movement of the internal gear, it can be eccentrically oscillated. Power can be efficiently transmitted to the output shaft.

( 2 ) The guide portion includes a shaft portion fixed to the fixing plate, a guide inner ring portion disposed so as to surround the shaft portion from the outside in the radial direction, and a guide inner ring portion arranged to surround the guide inner ring portion from the outside in the radial direction. and a plurality of guide ball portions rotatably held between the guide inner ring portion and the guide outer ring portion, wherein the guide outer ring portion is positioned in the housing recess. It may be inscribed in the inner wall surface.

In this case, the guide portion itself can function as a ball bearing, and the guide outer ring portion can be inscribed in the inner wall surface of the housing recess. Therefore, according to the movement of the internal gear, the guide outer ring portion can be inscribed with the inner wall surface of the housing recess while being rotated around the shaft portion. Therefore, the rotation (rolling) of the guide outer ring portion can be used for smooth movement instead of sliding the inner wall surface of the accommodation recess with respect to the guide outer ring portion. As a result, the frictional resistance between the guide portion and the accommodation recess can be reduced, and the power loss can be reduced. Therefore, power transmission efficiency can be improved, and power can be efficiently transmitted from the input shaft to the output shaft without waste.

( 3 ) The internal tooth may have a circular outer shape in a plan view seen from the direction of the eccentric axis, and may have rolling elements capable of rotating.

In this case, since the internal teeth have rolling elements that can rotate on their own axes, the internal gears are rotated relative to the external gears so that the rolling elements successively ride over the external teeth in the circumferential direction while the rolling elements are rotated. Can be eccentrically oscillated. Therefore, frictional resistance between the internal gear and the external gear can be reduced, and power loss can be reduced. Therefore, power transmission efficiency can be improved, and power can be efficiently transmitted from the input shaft to the output shaft without waste.

( 4 ) The rolling elements may be balls.

In this case, since the rolling elements are balls, the balls and the external teeth can be brought into point contact, and the frictional resistance between the internal gear and the external gear can be further effectively reduced. Therefore, power transmission efficiency can be further improved.

( 5 ) The external tooth may be formed with a tooth profile along a trochoidal curve.

In this case, since the external teeth have a so-called trochoidal tooth profile, when the internal gear eccentrically oscillates, the external teeth and the internal teeth can always be kept in contact with each other. It is easy to efficiently transmit power to the side.

( 6 ) An input inner ring portion integrally combined with the input shaft and arranged around the eccentric axis, and an input outer ring arranged so as to surround the input inner ring portion from the outside in the radial direction. and a plurality of input balls rollably held between the input inner ring portion and the input outer ring portion, wherein the internal gear is integrated with the input outer ring portion. May be combined.

In this case, the input shaft and the internal gear can be combined via the ball bearing composed of the input inner ring portion, the input outer ring portion, and the input balls, so that the ease of assembly can be improved. , the internal gear can be smoothly eccentrically oscillated with the rotation of the input shaft.

( 7 ) The output shaft may be integrally formed with the external gear.

In this case, since the output shaft and the external gear can be integrated, it is easy to further reduce the size and thickness of the transmission.

ADVANTAGE OF THE INVENTION According to this invention, it can be set as the transmission device which can be made easy to achieve size reduction and thickness reduction, and can lead to cost reduction and improvement of maintainability.

1 is an external perspective view showing an embodiment of a speed reducer (transmission device) according to the present invention; FIG. FIG. 2 is a vertical cross-sectional view of the speed reducer taken along line AA shown in FIG. 1; FIG. 2 is a perspective view showing a state in which an upper fixing plate is removed from the state shown in FIG. 1; It is the perspective view which looked at the input shaft shown in FIG. 2 from the upper end part side. 4 is a perspective view of the internal gear shown in FIG. 3 as viewed from above; FIG. FIG. 6 is a plan view of the internal gear shown in FIG. 5; It is the perspective view which looked at the internal gear shown in FIG. 5 from the downward side. FIG. 4 is a perspective view showing a state in which a ring plate is removed from the state shown in FIG. 3; FIG. 4 is a plan view showing a state in which a ring plate is removed from the state shown in FIG. 3; 3 is a perspective view of the guide member shown in FIG. 2; FIG. FIG. 11 is a vertical sectional view of the guide member taken along line BB shown in FIG. 10; FIG. 7 is a plan view showing an operating state of eccentric oscillation of the internal gear shown in FIG. 6; 13 is a plan view showing an operating state in which the internal gear is eccentrically oscillated counterclockwise from the state shown in FIG. 12; FIG. 14 is a plan view showing an operating state in which the internal gear further eccentrically swings counterclockwise from the state shown in FIG. 13; FIG. FIG. 15 is a plan view showing an operating state in which the internal gear further eccentrically oscillates counterclockwise from the state shown in FIG. 14; FIG. 5 is a diagram showing the relationship between internal teeth and external teeth during eccentric oscillation of the internal gear. It is a figure which shows the modification of the external tooth in an external gear.

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a transmission device according to the present invention will be described below with reference to the drawings. In this embodiment, a case where the transmission device is applied to a speed reducer having a speed reduction ratio of 1/16 will be described as an example.

As shown in FIGS. 1 and 2, a speed reducer (transmission device according to the present invention) 1 of this embodiment includes an input shaft 2, an internal gear 4 having a plurality of internal teeth 3, and a plurality of external teeth 5. , an output shaft 7, and a casing 8.

The input shaft 2 and the output shaft 7 are arranged so that their central axes are positioned on a common common axis. In this embodiment, this common axis is referred to as a rotation axis (axis according to the present invention) O1, and a direction intersecting the rotation axis O1 in a plan view seen from the rotation axis O1 is referred to as a radial direction. The direction of rotation is called the circumferential direction. Furthermore, the direction along the rotation axis O1 is called the up-down direction. Of the vertical directions, the direction from the input shaft 2 to the output shaft 7 is called upward, and the opposite direction is called downward.

(casing)
First, the casing 8 will be explained.
The casing 8 is provided with an upper fixing plate 10 and a lower fixing plate (fixing plate according to the present invention) 11 integrally combined with each other in a state of facing each other with a predetermined distance in the vertical direction.

The upper fixing plate 10 is formed in a square shape in plan view with a constant thickness. However, the outer shape of the upper fixing plate 10 is not limited to a square shape in plan view, and may be, for example, a circular shape, an elliptical shape, or a polygonal shape in plan view.
A through hole 15 is formed in the central portion of the upper fixing plate 10 so as to pass through the upper fixing plate 10 in the vertical direction. The through hole 15 is arranged coaxially with the rotation axis O1 and formed in a circular shape in plan view.

Of the four corners (four corners) of the upper fixed plate 10, a pair of corners arranged diagonally across the rotation axis O1 are provided with connecting holes (not shown) penetrating the upper fixed plate 10 in the vertical direction. formed. Positioning holes 16 penetrating through the upper fixing plate 10 in the vertical direction are respectively formed in the remaining pair of corners of the four corners (four corners) of the upper fixing plate 10 .

Further, the upper fixed plate 10 is formed with a plurality of support holes 17 arranged at regular intervals in the circumferential direction around the rotation axis O1.
The support hole 17 is formed so as to pass through the upper fixing plate 10 in the vertical direction and has a circular shape in a plan view. In the illustrated example, four support holes 17 are formed at intervals of 90 degrees around the rotation axis O1. However, the number of support holes 17 is not limited to this case.

The lower fixing plate 11 has the same configuration as the upper fixing plate 10 described above. Therefore, with respect to the lower fixing plate 11, the same components as those of the upper fixing plate 10 are denoted by the same reference numerals, and detailed description thereof will be omitted.
By forming the upper fixing plate 10 and the lower fixing plate 11 to have the same structure, one fixing plate can be used as either the upper fixing plate 10 or the lower fixing plate 11, thereby simplifying the structure. can.

However, the upper fixing plate 10 and the lower fixing plate 11 do not need to have the same configuration, and for example, the upper fixing plate 10 and the lower fixing plate 11 may have different outer shapes, outer sizes, different thicknesses, and the like.
In particular, the four support holes 17 need only be formed in the lower fixing plate 11 and need not be formed in the upper fixing plate 10 .

As shown in FIGS. 1 to 3, a pair of first spacers 18 and a pair of second spacers 19 are arranged between the upper fixing plate 10 and the lower fixing plate 11 configured as described above. .
The first spacer 18 is formed in a cylindrical shape having a predetermined length in the vertical direction, and is arranged between the communicating hole in the upper fixing plate 10 and the communicating hole in the lower fixing plate 11 . The first spacer 18 has screw holes 18a formed in its upper and lower end surfaces (see FIG. 3).

The second spacer 19 is formed in a cylindrical shape having the same vertical length as the first spacer 18, and is arranged between the positioning hole 16 in the upper fixing plate 10 and the positioning hole 16 in the lower fixing plate 11. there is The upper end surface of the second spacer 19 is formed with an upper positioning pin 19 a that protrudes upward and is inserted into the positioning hole 16 of the upper fixing plate 10 . A lower positioning pin (not shown) is formed on the lower end surface of the second spacer 19 so as to protrude downward and be inserted into the positioning hole 16 in the lower fixing plate 11 .

As a result, the upper fixing plate 10 and the lower fixing plate 11 are vertically spaced apart by the length of the first spacer 18 and the second spacer 19 as shown in FIGS. They are combined via spacers 18 and second spacers 19 .
A pair of connecting screws 20 are screwed into the screw holes 18a of the first spacer 18 from above through the communicating holes of the upper fixing plate 10, and the pair of connecting screws 20 are screwed into the first spacer 18 through the communicating holes of the lower fixing plate 11. It is screwed into the screw hole 18a from below. Thereby, the upper fixing plate 10 and the lower fixing plate 11 are integrally combined via the first spacer 18 and the second spacer 19 .

The internal gear 4 and the external gear 6 are arranged inside the casing 8 configured as described above, that is, between the upper fixed plate 10 and the lower fixed plate 11 .
Although the casing 8 of the present embodiment has a configuration in which the periphery of the internal gear 4 and the external gear 6 is open, the present invention is not limited to this case. A wall panel or the like may be attached between the upper fixing plate 10 and the lower fixing plate 11 .

(input shaft)
As shown in FIG. 2, the input shaft 2 is arranged along the vertical direction, and is arranged to be rotatable around the rotation axis O1 by power (torque) transmitted from the outside. In the illustrated example, the input shaft 2 is formed in a hollow cylindrical shape, but it is not limited to this case, and may be formed solid.

The input shaft 2 is arranged so that its upper end enters the through hole 15 from below the lower fixing plate 11 . At this time, the upper end of the input shaft 2 is kept out of contact with the through hole 15 . Further, the upper end surface of the input shaft 2 is formed with a fitting hole 2a recessed downward as shown in FIGS. The fitting hole 2a is formed in a circular shape in a plan view around an eccentric axis O2 radially eccentric from the rotation axis O1.

A direction intersecting the eccentric axis O2 in a plan view seen from the direction of the eccentric axis O2 is called a radial direction, and a direction rotating around the eccentric axis O2 is called a circumferential direction. In particular, in the description of the constituent members arranged around the eccentric axis O2, the eccentric axis O2 is used as a reference when simply referring to "radial direction, circumferential direction".

(Internal gear)
As shown in FIGS. 1 and 2, the internal gear 4 is arranged between the upper fixed plate 10 and the lower fixed plate 11 as previously described. Specifically, the internal gear 4 is arranged closer to the lower fixing plate 11 than the external gear 6 is. As a result, the external gear 6 is arranged above the internal gear 4 (that is, one side in the direction of the rotation axis O1), and the lower fixing plate 11 is arranged below the internal gear 4 (that is, on the other side in the direction of the rotation axis O1). side).

As shown in FIGS. 2 and 5 to 7, the internal gear 4 is arranged around the eccentric axis O2, operates with the rotation of the input shaft 2, and rotates around the eccentric axis O2. It has a plurality of inner teeth 3 which are spaced apart in the direction.
Details will be described below.

The internal gear 4 is arranged so as to face the lower fixed plate 11 in the vertical direction. and an annular gear wall portion (gear body according to the present invention) 31 projecting upward over the entire circumference.

The internal gear plate 30 is fitted inside the first spacer 18 and the second spacer 19, and has an outer diameter size such that a predetermined gap is secured between the first spacer 18 and the second spacer 19. is stipulated.
The internal gear plate 30 is formed with sufficient thickness so as to have appropriate rigidity (mechanical strength). In the illustrated example, the internal gear plate 30 is formed slightly thicker than the upper fixed plate 10 and the lower fixed plate 11 .

A fitting recess 32 (see FIG. 2) recessed downward from the upper surface is formed in the central portion of the internal gear plate 30 coaxially with the eccentric axis O2. The fitting recess 32 is formed in a circular shape in plan view, and has an inner diameter larger than the diameter of the input shaft 2, for example.

Further, the internal gear plate 30 is formed with a housing recess 33 penetrating the internal gear plate 30 in the vertical direction. It should be noted that the accommodation recess 33 does not need to penetrate the internal gear plate 30 in the vertical direction, and may be open at least toward the lower fixed plate 11 side.
The accommodation recesses 33 are formed in a circular shape having a predetermined inner diameter in a plan view, and are formed in plural at equal intervals in the circumferential direction around the eccentric axis O2. In the illustrated example, four housing recesses 33 are formed at intervals of 90 degrees around the eccentric axis O2.

In particular, the accommodation recesses 33 are formed so as to be arranged above the four support holes 17 formed in the lower fixing plate 11 . Specifically, the accommodation recesses 33 are formed so that the support holes 17 are positioned inside the accommodation recesses 33 in a plan view of the internal gear plate 30 . Note that the number of housing recesses 33 is not limited to four.

Further, the internal gear plate 30 is formed with a plurality of lightening recesses 35 recessed downward in portions other than the fitting recesses 32 and the accommodation recesses 33 described above.
The lightening recesses 35 are not essential and may not be formed, but if the internal gear plate 30 has a sufficient thickness, they are preferably formed from the viewpoint of weight reduction. Further, the shape and number of the lightening recesses 35 may be changed as appropriate, and they may be formed so as to penetrate the internal gear plate 30 in the vertical direction.

The gear wall portion 31 is formed to protrude upward from the upper surface of the internal gear plate 30 along the outer peripheral edge of the internal gear plate 30 . Thereby, the gear wall portion 31 surrounds the external gear 6 from the outside in the radial direction.

A bulging portion 36 that bulges outward in the radial direction is formed on the outer peripheral surface side of the gear wall portion 31 . The bulging portion 36 extends vertically from the upper end surface of the gear wall portion 31 to the lower surface of the internal gear plate 30, and has a semicircular shape extending radially outward when the internal gear plate 30 is viewed from above. It is formed so as to bulge out. The bulging portion 36 is formed with a screw hole 36a opening upward.
A plurality of bulging portions 36 configured in this manner are formed at equal intervals in the circumferential direction around the eccentric axis O2. Specifically, four bulging portions 36 are formed. However, the number of bulging portions 36 is not limited to four, and may be changed as appropriate.

A plurality of internal teeth 3 are formed on the inner peripheral surface side of the gear wall portion 31 and are arranged at equal intervals in the circumferential direction around the eccentric axis O2 over the entire circumference of the gear wall portion 31. ing.
The internal gear 3 has a circular outer shape in plan view of the internal gear plate 30 and has balls 37 as rolling elements capable of rotating on its axis.
Further, the internal teeth 3 are positioned on both sides in the circumferential direction sandwiching the ball housing portion 38 formed so as to be recessed radially outward from the inner peripheral surface of the gear wall portion 31 and the ball housing portion 38 . and a holding claw 39 that protrudes radially inward from the inside of the wall portion 31 and holds the ball 37 so that it can roll.

The balls 37 are accommodated in the ball accommodating portions 38 while being placed on the upper surface of the internal gear plate 30, and are rotatably held by the holding claws 39 without protruding radially inward. The balls 37 protrude radially inward from the holding claws 39 and are capable of contacting and meshing with the external teeth 5 of the external gear 6 .
The outline connecting the outer peripheral surface of the ball 37 and the outer peripheral surface of the holding claws 39 that hold the ball 37 from both sides in the circumferential direction has a smooth tooth shape protruding inward in the radial direction. .

The internal teeth 3 having the balls 37 configured as described above are formed to have 17 teeth (that is, 17 balls 37). Therefore, the internal teeth 3 are arranged at intervals of approximately 21 degrees around the eccentric axis O2.

Furthermore, as shown in FIGS. 2 and 3, a ring plate 40 is superimposed on the gear wall portion 31 from above.
The ring plate 40 is arranged coaxially with the eccentric axis O<b>2 and formed into a ring shape having the same diameter as the outer diameter of the gear wall portion 31 . Further, the ring plate 40 is formed with a flange portion that protrudes radially outward from the outer peripheral edge portion and overlaps the bulging portion 36 of the internal gear 4 . The ring plate 40 is integrally combined with the gear wall portion 31 so as to cover the balls 37 from above by connecting screws 41 screwed into the screw holes 36a of the bulging portion 36 via the flange portion. ing. As a result, each ball 37 is restricted from coming out upward from the ball accommodating portion 38 by the ring plate 40 .

The internal gear 4 configured as described above, except for the balls 37, is integrally formed by, for example, metal material shaving or die-cutting, or synthetic resin material injection molding.

(central bearing)
The internal gear 4 configured as described above is combined with the input shaft 2 via a central bearing 50 as shown in FIG.
The central bearing 50 is integrally combined with the upper end portion of the input shaft 2 and has an input inner ring portion 51 arranged around the eccentric axis O2 and an input outer ring portion surrounding the input inner ring portion 51 from the outside in the radial direction. 52 and a plurality of input balls 53 rotatably held between the input inner ring portion 51 and the input outer ring portion 52 .

The input inner ring portion 51 includes a first inner ring portion 55 that is combined with the upper end portion of the input shaft 2 and a second inner ring portion 56 that overlaps the first inner ring portion 55 from above.
The first inner ring portion 55 includes a fitting shaft portion 57 closely fitted inside a fitting hole 2 a formed in the upper end surface of the input shaft 2 , and a radially outer side of the fitting shaft portion 57 from the upper end portion of the fitting shaft portion 57 . and an annular flange portion 58 formed to extend toward.

The fitting shaft portion 57 is arranged coaxially with the eccentric axis O2 and slightly protrudes upward from the fitting hole 2a. Further, the upper end surface of the fitting shaft portion 57 is a flat surface. The fitting shaft portion 57 is formed with a threaded hole 57a opening upward coaxially with the eccentric axis O2.
A first inner rolling surface 58a is formed on the outer peripheral surface of the flange portion 58 over the entire circumference. The first inner rolling contact surface 58a is formed in a tapered shape in vertical cross-section that extends radially inward as it goes upward from the outer peripheral surface of the flange portion 58 . Thereby, the first inner rolling surface 58a is formed so as to face radially outward and obliquely upward.

The second inner ring portion 56 is a disk plate that overlaps the upper end surface of the fitting shaft portion 57 and is arranged coaxially with the eccentric axis O2. A second inner rolling surface 56 a is formed on the outer peripheral surface of the second inner ring portion 56 over the entire circumference. The second inner rolling contact surface 56a is formed in a tapered shape in vertical cross-section that extends radially inward as it goes downward from the outer peripheral surface of the second inner ring portion 56 . Thereby, the second inner rolling surface 56a is formed so as to face radially outward and obliquely downward.

The second inner ring portion 56 configured in this manner is combined with the first inner ring portion 55 by a connecting screw 59 screwed into the screw hole 57a. The input inner ring portion 51 composed of the first inner ring portion 55 and the second inner ring portion 56 that are combined with each other has a fitting shaft portion 57 that is tightly fitted inside the fitting hole 2a. 2 are integrally combined.

Further, the first inner rolling surface 58a and the second inner rolling surface 56a form an inner annular groove 60 having a V-shaped longitudinal cross-sectional view and an opening angle of approximately 90 degrees on the outer peripheral surface side of the input inner ring portion 51. It is formed to be recessed radially inward.

The input outer ring portion 52 includes a first outer ring portion 65 that surrounds the first inner ring portion 55 from the outside in the radial direction, and a second outer ring portion 66 that surrounds the second inner ring portion 56 from the outside in the radial direction.
The first outer ring portion 65 is formed in a ring shape coaxial with the eccentric axis O<b>2 and integrally formed such that the outer peripheral edge portion is connected to the inside of the fitting recess 32 . However, it is not limited to this case, and the first outer ring portion 65 may be tightly fitted inside the fitting recess 32 .
A first outer rolling surface 65 a is formed on the inner peripheral surface of the first outer ring portion 65 over the entire circumference. The first outer rolling contact surface 65a is formed in a tapered shape in a vertical cross-section that extends radially outward from the inner peripheral surface of the first outer ring portion 65 upward. Thereby, the first outer rolling surface 65a is formed to face radially inward and obliquely upward.

The second outer ring portion 66 is formed in a ring shape coaxial with the eccentric axis O<b>2 and tightly fitted inside the fitting recess 32 .
A second outer rolling surface 66 a is formed on the inner peripheral surface of the second outer ring portion 66 over the entire circumference. The second outer rolling contact surface 66a is formed in a tapered shape in vertical cross section extending radially outward from the inner peripheral surface of the second outer ring portion 66 downward. Thereby, the second outer rolling surface 66a is formed to face radially inward and obliquely downward.

The input outer ring portion 52 and the internal gear 4 configured as described above are integrally combined. Further, the first outer rolling surface 65a and the second outer rolling surface 66a form an outer annular groove having an opening angle of approximately 90 degrees on the inner peripheral surface side of the input outer ring portion 52 and having a V-shaped longitudinal cross-sectional view. 61 is formed so as to be recessed radially outward. Therefore, an annular space is defined between the inner annular groove 60 and the outer annular groove 61 described above.

The input balls 53 are accommodated in the annular space at intervals in the circumferential direction. In this embodiment, the plurality of input balls 53 are arranged in the annular space while being circumferentially positioned by a retainer 53a.
However, the present invention is not limited to this case. For example, the input balls 53 may be arranged in the annular space so as to line up in the circumferential direction while being in contact with each other without gaps. That is, a full-ball configuration in which the input balls 53 are arranged without gaps over the entire circumference of the annular space may be employed.

Furthermore, the plurality of input balls 53 have a first inner rolling surface 58 a and a second inner rolling surface 56 a formed on the input inner ring portion 51 side, and a first outer rolling surface 58 a formed on the input outer ring portion 52 side. It is held so as to be able to roll while in contact with the moving surface 65a and the second outer rolling surface 66a (four-point contact state).

Since the input shaft 2 and the internal gear 4 are combined via the central bearing 50 configured as described above, the power transmitted to the input shaft 2 can be transmitted to the internal gear 4 via the central bearing 50. It is possible.

(external gear)
As shown in FIGS. 2, 8 and 9 , the external gear 6 is arranged closer to the upper fixed plate 10 than the internal gear 4 and inside the gear wall portion 31 of the internal gear 4 .
The external gear 6 is arranged coaxially with the rotation axis O1, is rotatable around the rotation axis O1, and has a plurality of external teeth 5 that can inscribe and mesh with the plurality of internal teeth 3. there is At the center of the external gear 6, a fitting hole 6a is formed coaxially with the axis line to penetrate the external gear 6 in the vertical direction.

The plurality of external teeth 5 are arranged at equal intervals in the circumferential direction around the rotation axis O1, and are arranged so that the number of teeth is different from the number of teeth of the internal teeth 3 (17 teeth). Specifically, the external teeth 5 are arranged to have 16 teeth, which is one less than the internal teeth 3 . Therefore, the external teeth 5 are arranged at intervals of approximately 22.5 degrees around the rotation axis O1.
Furthermore, the external teeth 5 of this embodiment have a tooth profile along a trochoidal curve, that is, a so-called trochoidal tooth profile. This allows the balls 37 of the plurality of internal teeth 3 and the plurality of external teeth 5 to be in constant contact.

(output shaft)
As shown in FIGS. 2 and 8, the output shaft 7 is arranged along the vertical direction and arranged to be rotatable around the rotation axis O1. In the illustrated example, the output shaft 7 is formed in a hollow cylindrical shape, but is not limited to this case, and may be formed solid.

The output shaft 7 is arranged to enter the through hole 15 from above the upper fixing plate 10 . At this time, the output shaft 7 is kept out of contact with the through hole 15 . A lower end portion of the output shaft 7 is tightly fitted inside a fitting hole 6 a formed in the external gear 6 . As a result, the output shaft 7 is integrally combined with the external gear 6 and is rotatable about the rotation axis O1 as the external gear 6 rotates.

(Guide member)
In the speed reducer 1 configured as described above, the movement (behavior) of the internal gear 4 is controlled by the guide member 70, as shown in FIGS. The guide member 70 is fixed to the lower fixed plate 11 and serves to constrain the rotation of the internal gear 4 and to guide the internal gear 4 so as to eccentrically oscillate about the rotation axis O1.
Details will be described below.

The guide members 70 are provided corresponding to the number of the support holes 17 formed in the lower fixed plate 11 and the number of the housing recesses 33 formed in the internal gear 4 . Therefore, in this embodiment, four guide members 70 are provided. Since the four guide members 70 all have the same configuration, only one guide member 70 will be described in detail, and the remaining guide members 70 will be given the same reference numerals as the common constituent members. Description is omitted.

The guide member 70 has a guide portion 71 held by the support hole 17 so as to stand upward from the lower fixing plate 11 . The guide portion 71 is accommodated in the accommodation recess 33 by entering the accommodation recess 33 of the internal gear 4 from below, and can be in contact with the inner wall surface of the accommodation recess 33 .
Accordingly, the four guide portions 71 are arranged at intervals of 90 degrees around the rotation axis O1 and are housed in the four housing recesses 33, respectively.

In particular, as shown in FIG. 6, the guide portion 71 is arranged in the housing recess 33 so as to be eccentric with respect to the center line O3 of the housing recess 33 by the amount of eccentricity H between the rotation axis O1 and the eccentric axis O2. It is Further, the direction in which the eccentric axis O2 is eccentric with respect to the rotation axis O1 and the direction in which the center line O4 of the guide portion 71 is eccentric with respect to the center line O3 of the housing recess 33 are the same. The guide portion 71 is held by the lower fixed plate 11 .

As shown in FIGS. 2, 10 and 11, the guide portion 71 includes a shaft portion 72 held in the support hole 17 and a guide fixed to the shaft portion 72 so as to surround the shaft portion 72 from the outside in the radial direction. An inner ring portion 73, a guide outer ring portion 74 that surrounds the guide inner ring portion 73 from the outside in the radial direction, and a plurality of guide balls 75 that are rotatably arranged between the guide inner ring portion 73 and the guide outer ring portion 74. I have.

The shaft portion 72 has its lower end portion tightly fitted inside the support hole 17 . As a result, the entire guide member 70 is fixed to the lower fixing plate 11 . The shaft portion 72 may be fitted inside the support hole 17 so as to be rotatable. The upper end of the shaft portion 72 enters the housing recess 33 from below.

The guide inner ring portion 73 is fixed to the upper end portion of the shaft portion 72 . An outer peripheral surface of the guide inner ring portion 73 is formed with an inner rolling surface 73a on which the guide ball 75 rolls.

The guide outer ring portion 74 includes a first guide outer ring portion 76 that surrounds the guide inner ring portion 73 from the outside in the radial direction, and a guide outer ring portion 76 that further surrounds the first guide outer ring portion 76 from the radial outside. It has a second guide outer ring portion 77 that is integrally combined. An outer rolling surface 76 a on which the guide ball 75 rolls is formed on the inner peripheral surface of the first guide outer ring portion 76 .

The guide balls 75 are housed in an annular space formed between the guide inner ring portion 73 and the first guide outer ring portion 76 with a space therebetween in the circumferential direction. 76a. The plurality of guide balls 75 are arranged in the annular space while being positioned in the circumferential direction by a retainer (not shown).
However, the present invention is not limited to this case. For example, the guide balls 75 may be arranged in the annular space so as to line up in the circumferential direction while being in contact with each other without gaps. That is, a full-ball configuration in which the guide balls 75 are arranged without gaps over the entire circumference of the annular space may be employed.

Further, a plurality of ball holding holes 77a that are recessed radially inward are formed on the outer peripheral surface side of the second guide outer ring portion 77 at equal intervals over the entire circumference. Contact balls 78 that can come into contact with the inner wall surface of the accommodation recess 33 are rotatably held in the plurality of ball holding holes 77a.
The guide outer ring portion 74 is integrally combined with a restricting ring 79 that restricts the contact ball 78 from coming out upward from the ball retaining hole 77a.

The guide member 70 configured as described above can be internally contacted with the inner wall surface of the accommodation recess 33 via the contact ball 78 .
As a result, the rotation of the internal gear 4 can be restrained by using the four guide members 70 fixed to the lower fixed plate 11, and the internal gear 4 can be eccentrically oscillated about the rotation axis O1. It is possible to guide and control its movement.

(Action of reducer)
Next, a case of operating the speed reducer 1 configured as described above will be described.
In this case, for example, when power from an external drive source (eg, stepping motor, etc.) is transmitted to the input shaft 2 shown in FIG. 2, the input shaft 2 rotates around the rotation axis O1. Thereby, the rotational force transmitted to the input shaft 2 can be transmitted to the internal gear 4 via the center bearing 50 (input inner ring portion 51, input ball 53, and input outer ring portion 52). Therefore, as the input shaft 2 rotates, the internal gear 4 behaves such that it eccentrically rotates counterclockwise around the rotation axis O1 as indicated by an arrow K1 in FIG. 12, for example.

However, the rotation of the internal gear 4 is restrained by the guide member 70 fixed by the lower fixing plate 11, so that the eccentric oscillation about the rotation axis O1 is changed from the eccentric rotation about the rotation axis O1. is controlled by

Specifically, the guide portion 71 arranged in the housing recess 33 is eccentric with respect to the center line O3 of the housing recess 33 by the amount of eccentricity H between the rotation axis O1 and the eccentric axis O2 (Fig. 6). Therefore, even if the internal gear 4 behaves eccentrically around the rotation axis O1 as the input shaft 2 rotates, the inner wall surface of the housing recess 33 and the guide portion 71 are in contact with each other. can be constrained appropriately. In addition, the internal gear 4 can be eccentrically oscillated while the guide portion 71 is inscribed in the inner wall surface of the housing recess 33 . Therefore, while guiding the movement of the internal gear 4 using the guide portion 71, the internal gear 4 is eccentrically oscillated counterclockwise as shown by the arrow K2 as if it were eccentrically rotated around the guide portion 71. be able to.

As a result, as shown in FIG. 12 , the outer gear 6 is rotated so that the inner teeth 3 sequentially ride over the outer teeth 5 in the circumferential direction while the plurality of outer teeth 5 are inscribed in the plurality of inner teeth 3 . The internal gear 4 can be eccentrically oscillated.
More specifically, when the inner wall surface of the accommodation recess 33 and the guide portion 71 are inscribed in the first inscribed region P1, when the internal gear 4 eccentrically oscillates counterclockwise about the rotation axis O1, As shown in FIG. 13, the inner wall surface of the housing recess 33 and the guide portion 71 are inscribed in the second inscribed region P2. The second inscribed region P2 is located on the counterclockwise side of the first inscribed region P1 along the inner wall surface of the housing recess 33 .

Next, when the internal gear 4 further eccentrically swings counterclockwise, as shown in FIG. 14, the inner wall surface of the housing recess 33 and the guide portion 71 are inscribed in the third inscribed region P3. The third inscribed region P3 is located on the counterclockwise side of the second inscribed region P2 along the inner wall surface of the housing recess 33 .
Next, when the internal gear 4 further eccentrically swings counterclockwise, as shown in FIG. 15, the inner wall surface of the housing recess 33 and the guide portion 71 are inscribed in the fourth inscribed region P4. The fourth inscribed region P4 is located along the inner wall surface of the housing recess 33 on the counterclockwise side of the first inscribed region P1.

In this manner, the internal gear 4 performs eccentric oscillation such that the states shown in FIGS. 12 to 15 are repeated in order. Each time the internal gear 4 gets over the external teeth 5 with the eccentric oscillation of the internal gear 4, the external teeth 5 can be pressed in the circumferential direction via the internal teeth 3 as indicated by arrow F in FIG. The external gear 6 can be rotated around the rotation axis O1 in the clockwise direction opposite to the internal gear 4 (in the direction of the arrow K2). An arrow F extends from the center point of the balls 37 forming the internal teeth 3 to the point of contact between the balls 37 and the external teeth 5 .

As described above, the power transmitted to the input shaft 2 is transmitted to the internal gear 4 to cause the internal gear 4 to eccentrically oscillate. Power can be transmitted to gear 6 . As a result, as shown in FIG. 12, the external gear 6 and the output shaft 7 can be rotated clockwise about the rotation axis O1.
In particular, since the number of teeth of the external teeth 5 (16 teeth) and the number of teeth of the internal teeth 3 (16 teeth, i.e., 16 balls 37) are different, the external gear 6 is decelerated by the angular difference of the number of teeth (deceleration). ratio 1/16). As a result, the output shaft 7 can be rotated while being decelerated with respect to the rotation of the input shaft 2 .

In particular, the speed reducer 1 of this embodiment differs from conventional speed reducers and the like in that the internal gear 4 side is eccentrically oscillated. can be done. Therefore, for example, it is not necessary to extract only the rotation component of the external gear 6, and power can be transmitted directly from the external gear 6 to the output shaft 7 to rotate the output shaft 7 around the rotation axis O1.
Therefore, it is possible to achieve a simple structure with a reduced number of parts, and it is possible to reduce the overall size and thickness of the speed reducer 1 . In addition, it can lead to cost reduction and improvement of maintainability.

As described above, according to the speed reducer 1 of the present embodiment, it is easy to achieve reduction in size and thickness, which can lead to cost reduction and improvement in maintainability.
In particular, since the speed reducer 1 can be easily reduced in size and thickness, it can be suitably used for small parts in various fields. For example, the speed reducer 1 can be used in various devices that move small moving parts (for example, industrial robots, robot arms, robot hands, medical support devices that support the movement of patients, home appliances, AV devices, etc.). It can be used suitably.

Furthermore, according to the speed reducer 1 of the present embodiment, the movement of the internal gear 4 can be eccentrically oscillated while guiding the movement of the internal gear 4 using the guide portion 71, so that the internal gear 4 can be stabilized with little backlash. It can be eccentrically oscillated, and power can be efficiently transmitted from the input shaft 2 to the output shaft 7. - 特許庁

In particular, the guide portion 71 itself can function as a ball bearing, and the guide outer ring portion 74 can be inscribed on the inner wall surface of the housing recess 33 . Therefore, according to the movement of the internal gear 4 , the guide outer ring portion 74 can be brought into contact with the inner wall surface of the housing recess 33 while rotating around the shaft portion 72 . Therefore, the rotation (rolling) of the guide outer ring portion 74 is used to smoothly move the inner wall surface of the accommodation recess 33 against the guide outer ring portion 74 . As a result, frictional resistance between the guide portion 71 and the housing recess 33 can be reduced, and power loss can be reduced. Therefore, power transmission efficiency can be improved, and power can be efficiently transmitted from the input shaft 2 to the output shaft 7 without waste.

In addition, in this embodiment, a contact ball 78 is further rotatably held by the guide outer ring portion 74 , and can be inscribed with the inner wall surface of the housing recess 33 via the contact ball 78 . Therefore, the effects described above can be achieved more effectively.

Further, since the internal teeth 3 have balls 37, the internal gear 4 is rotated by the external gear so that the balls 37 sequentially get over the external teeth 5 in the circumferential direction while rotating the balls 37 as shown in FIG. 6 can be eccentrically oscillated. Therefore, frictional resistance between the internal gear 4 and the external gear 6 can be reduced, and power loss can be reduced. Therefore, power transmission efficiency can be improved, and power can be efficiently transmitted from the input shaft 2 to the output shaft 7 without waste.
In particular, since the balls 37 and the external teeth 5 can be brought into point contact, the frictional resistance between the internal gear 4 and the external gear 6 can be effectively reduced.

Furthermore, since the external teeth 5 have a so-called trochoidal tooth profile, when the internal gear 4 eccentrically oscillates, the external teeth 5 and the internal teeth 3 can always be kept in contact with each other. It is easy to efficiently transmit power to the external gear 6 side.

Furthermore, since the input shaft 2 and the internal gear 4 can be combined via the central bearing 50 composed of the input inner ring portion 51, the input outer ring portion 52, and the input balls 53, the ease of assembly is improved. In addition, the internal gear 4 can be smoothly eccentrically oscillated as the input shaft 2 rotates.

Although embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. Embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. Embodiments and modifications thereof include, for example, those that can be easily imagined by those skilled in the art, those that are substantially the same, and those within an equivalent range.

For example, in the above embodiment, the case where the speed reduction ratio is set to 1/16 has been described as an example, but the present invention is not limited to this case, and the speed reduction ratio may be changed as appropriate. In this case, the relationship between the number of teeth of the internal teeth 3 and the number of teeth of the external teeth 5 may be appropriately changed according to the reduction ratio.

Further, in the above embodiment, the ball 37 is used as a part of the inner tooth 3, but the ball 37 is not limited to the ball 37. For example, a cylindrical pin may be used as the rolling element. Furthermore, the internal teeth 3 may be configured to have, for example, a trochoidal tooth profile without using rolling elements. Even in these cases, the same effects as those of the above-described embodiment can be achieved.

Furthermore, in the above embodiment, the guide portion 71 constituting the guide member 70 employs a ball bearing structure including the guide inner ring portion 73, the guide outer ring portion 74, and the guide balls 75, but is not limited to this case.
For example, the guide portion 71 may be composed of a slide bearing whose outer ring portion is slidably supported around the shaft portion 72 , and the outer ring portion may be inscribed with the inner wall surface of the housing recess 33 . Even in this case, similar effects can be achieved. In particular, it is effective when the size of the housing recess 33 is reduced. Therefore, it is effective for further miniaturization of the internal gear 4 .
Furthermore, the guide portion 71 itself may be, for example, a cylindrical pin or the like. Even in this case, since the outer peripheral surface of the pin can be inscribed with the inner wall surface of the housing recess 33, the same effect can be obtained. In particular, it is effective for further miniaturization of the internal gear 4 .

Furthermore, in the above embodiment, the first inner ring portion 55 and the input shaft 2 in the center bearing 50 may be integrally formed, and the output shaft 7 and the external gear 6 may be integrally formed. In these cases, it is easy to further reduce the size and thickness of the speed reducer 1 .
Furthermore, the central bearing 50 is not essential and may be omitted. In this case, the internal gear 4 may be directly combined with the input shaft 2 while being eccentric with respect to the input shaft 2 .

Furthermore, in the above-described embodiment, as shown in FIG. When the ball 37 is in contact with the region other than the tip 5a side and the tooth bottom 5b side, the external teeth 5 can be efficiently pressed in the circumferential direction, which greatly contributes to power transmission.
Conversely, when the balls 37 are in contact with the tooth tip 5a side and the tooth bottom 5b side of the external teeth 5, it is difficult to efficiently press the external teeth 5 in the circumferential direction, which contributes little to power transmission. do not do. In addition, when the phases of the internal gear 4 and the external gear 6 are shifted due to a combination error or the like between the external gear 6 and the internal gear 4, for example, the tooth top 5a side and the tooth bottom 5b side of the external tooth 5 are placed on the ball 37. movement may be affected.

Therefore, as shown in FIG. 17, the tooth tip 5a side and the tooth bottom 5b side of the external teeth 5 (that is, tooth groove portions located between the external teeth 5 adjacent in the circumferential direction) are cut by cutting or the like, A notched curved surface 5c may be formed. As a result, the ball 37 can be smoothly moved without hindering power transmission from the internal gear 3 to the external gear 5 and without being affected by a combination error or the like between the external gear 6 and the internal gear 4 .

O1... Rotational axis (axis)
O2... Eccentric axis line 1... Reducer (transmission device)
2 Input shaft 3 Internal tooth 4 Internal gear 5 External tooth 6 External gear 7 Output shaft 11 Lower fixing plate (fixing plate)
30... Internal gear plate 31... Gear wall portion (gear body)
33... Receiving recess 37... Ball 51... Input inner ring portion 52... Input outer ring portion 53... Input ball 70... Guide member 71... Guide portion 72... Shaft portion 73... Guide inner ring portion 74... Guide outer ring portion 75... Guide ball

Claims (7)

an input shaft that rotates about its axis by the transmitted power;
A plurality of internal teeth arranged around an eccentric axis eccentric with respect to the axis, actuated with rotation of the input shaft, and spaced apart in a circumferential direction orbiting about the eccentric axis. an internal gear having
An outer gear having a plurality of external teeth arranged to face the internal gear on one side in the axial direction and rotatable about the axis and capable of meshing with the plurality of internal teeth gears and
an output shaft that rotates around the axis as the external gear rotates;
The internal gear is fixed to a fixing plate arranged to face the internal gear on the other side in the axial direction, and constrains the rotation of the internal gear so as to eccentrically oscillate about the axis. a guide member for guiding the
The number of teeth of the external teeth is different from the number of teeth of the internal teeth ,
The internal gear is
a gear body provided with the internal teeth and surrounding the external gear from the outside in the radial direction;
an internal gear plate arranged to face the fixed plate and having the gear main body formed on the outer peripheral edge side;
a housing recess formed in the internal gear plate so as to open at least toward the fixed plate;
The guide member includes a guide portion that is arranged in the accommodation recess and that can be inscribed with an inner wall surface of the accommodation recess,
The transmission device , wherein the guide portion is arranged in the housing recess so as to be eccentric with respect to a center line of the housing recess by an amount of eccentricity between the axis and the eccentric axis . A transmission according to claim 1 , wherein
The guide part is
a shaft fixed to the fixing plate;
a guide inner ring portion disposed so as to surround the shaft portion from the outside in the radial direction;
a guide outer ring portion disposed so as to surround the guide inner ring portion from the outside in the radial direction;
a plurality of guide ball portions rollably held between the guide inner ring portion and the guide outer ring portion;
The transmission device, wherein the guide outer ring portion contacts the inner wall surface of the housing recess. 3. The transmission device according to claim 1 or 2 ,
The transmission device, wherein the internal tooth has a circular outer shape in a plan view seen from the direction of the eccentric axis, and has a rotatable rolling element. A transmission according to claim 3 , wherein
The transmission device, wherein the rolling elements are balls. In the transmission device according to any one of claims 1 to 4 ,
The transmission device, wherein the external teeth are formed with a tooth profile along a trochoidal curve. In the transmission according to any one of claims 1 to 5 ,
an input inner ring portion integrally combined with the input shaft and arranged around the eccentric axis;
an input outer ring portion disposed so as to surround the input inner ring portion from the radially outer side;
a plurality of input balls rotatably held between the input inner ring portion and the input outer ring portion;
The transmission device, wherein the internal gear is integrally combined with the input outer ring portion. In the transmission according to any one of claims 1 to 6 ,
The transmission device, wherein the output shaft is integrally formed with the external gear.

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