JP7309180B2 - reduction gear - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reduction gear that transmits rotational motion from an input section to an output section.

The phenomenon in which the driving system operates by applying an external force to the joints of the robot or the output shaft of the actuator is called backdrive, and the concept of the ease of backdriving is called backdrivability. Human-collaborative robots and haptic devices are required not only to have high output and high accuracy, but also to be easy to back drive against external forces.

One of the important factors that affect backdrivability is a power transmission device or speed reducer that transmits power from an input section such as a motor to an output section. Conventionally, spur gear trains, planetary gears, worm gears, etc. have been used for reduction gears.

In such a speed reducer using gears according to the prior art, sliding friction is generated between the meshing gears even during back driving, and the resistance prevents back driving.
SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a reduction gear transmission having a high reduction ratio, high efficiency, and high back drivability.

In order to achieve the above object, according to the present invention, in a reduction gear transmission for transmitting rotational motion from an input section to an output section, an input side rotary shaft forming the input section and a an input side winding drum having a small diameter portion and a large diameter portion; an output side rotating shaft extending parallel to the input side rotating shaft and forming the output portion; A swing shaft extending parallel to the rotation shaft and swingable around the output-side rotation shaft; a differential winding drum provided on the swing shaft; the input-side winding drum; A speed reducer is provided that includes a differential winding drum and a wire that is stretched between them.

According to the present invention, since the speed reducer does not use gears, there is no sliding friction between meshing gears, the friction during back driving is small, no backlash occurs, and lubrication is unnecessary. It has an effect of being excellent in quietness.

1 is a perspective view of a reduction gear transmission according to a first embodiment of the invention; FIG. FIG. 2 is a cross-sectional view of the reduction gear transmission of FIG. 1; FIG. 2 is a perspective view showing the positional relationship of first to third wires of the reduction gear transmission in the state shown in FIG. 1; 2 is a perspective view of the speed reducer showing a state in which the motor rotates in the direction indicated by arrow A1 from the state shown in FIG. 1; FIG. FIG. 5 is a perspective view showing the positional relationship of first to third wires of the reduction gear transmission in the state shown in FIG. 4; 2 is a perspective view of the speed reducer showing a state in which the motor rotates in the direction indicated by arrow A2 from the state shown in FIG. 1; FIG. FIG. 7 is a perspective view showing the positional relationship of first to third wires of the reduction gear transmission in the state of FIG. 6; FIG. 5 is a perspective view of a reduction gear transmission according to a second embodiment of the present invention; FIG. 5 is a cross-sectional view of a reduction gear transmission according to a third embodiment of the present invention;

Preferred embodiments of the present invention will now be described with reference to the accompanying drawings.
1 to 3, the reduction gear 10 according to the first embodiment includes a base member 12, a motor 14 as an input unit attached to the base member 12, a first winding drum 18 forming an input side winding drum, a second winding drum 46 forming a differential winding drum; wires 50, 52, 54, and the rotating shaft 26 and arms 30, 32 as output units. The base member 12 is a plate-like member fixed to a stationary part such as a frame (not shown) or a movable part such as a robot arm (not shown). has a hole 12a through which the output shaft 16 of the is passed.

A first winding drum 18 is fixed to the output shaft 16 so as to rotate together with the output shaft 16 . The first winding drum 18 has a small diameter portion 20 and a large diameter portion 22 having a larger diameter than the small diameter portion 20 . The small-diameter portion 20 and the large-diameter portion 22 are concentrically arranged and integrally formed. The small-diameter portion 20 and the large-diameter portion 22 have spiral grooves formed on their cylindrical outer surfaces to receive the first to third wires 50 , 52 , 54 .

A fixed shaft 24 is attached to the base member 12 . The fixed shaft 24 is a columnar or cylindrical member and extends substantially parallel to the central axis Oin of the output shaft 16 . A rotating shaft 26 forming an output side rotating shaft is rotatably supported on the cylindrical outer surface of the fixed shaft 24 via a bearing 28 around a central axis Oout of the fixed shaft 24 . First and second pulleys 34, 38 are rotatably supported around the central axis Oout by bearings 36, 40, respectively, on the cylindrical outer surface of the rotating shaft 26. As shown in FIG.

A pair of arms 30 and 32 are attached to each end of the rotating shaft 26 . A pair of arms 30 and 32 extend in a direction perpendicular to the central axis Oout of fixed shaft 24 . A swing shaft 42 is fixed to the tip of the arms 30 and 32 so as not to rotate with respect to the arms 30 and 32 . In this embodiment, the swing shaft 42 extends parallel to the central axis Oin of the output shaft 16 and the central axis Oout of the fixed shaft 24 . A second winding drum 46 is rotatably supported around the central axis Od of the fixed shaft 42 by bearings 48 on the cylindrical outer surface of the swing shaft 42 .

A first wire 50 has a first end 50 a fixed to the small diameter portion 20 of the first winding drum 18 and is wound around the small diameter portion 20 . The first wire 50 is further extended toward the second winding drum 46 so as to be disposed above the first pulley 34 as shown in FIG. 1, and wound around the second winding drum 46. . The first wire 50 is further extended toward the large diameter portion 22 of the first winding drum 18 so as to be disposed below the second pulley 38, and wound around the large diameter portion 22, A tip (second end) 50 b thereof is fixed to the large diameter portion 22 .

The second wire 52 is wound around the small diameter portion 20 of the first winding drum 18 with a first end portion 52 a fixed to the small diameter portion 20 . The second wire 52 is further extended toward the second winding drum 46 so as to be disposed below the first pulley 34, and then wound around the second winding drum 46 to A tip (second end) 52 b is fixed to the second winding drum 46 .

The third wire 54 is wound around the large diameter portion 22 of the first winding drum 18 with a first end portion 54 a fixed to the large diameter portion 22 . The third wire 54 is further extended toward the second winding drum 46 so as to be arranged above the second pulley 38, and then wound around the second winding drum 46 to (Second end) 54 b is fixed to the second winding drum 46 .

Second ends 52 b , 54 b of second and third wires 52 , 54 are preferably secured to opposite end portions of second winding drum 46 . The second and third wires 52, 54 are wound in opposite directions around the small diameter portion 20 and the large diameter portion 22, respectively. Similarly, the second and third wires 52, 54 are wound on the second winding drum 46 in opposite directions.

Further, the first ends 50a, 52a of the first and second wires 50, 52 are secured to opposite end portions of the reduced diameter portion 20, the first and second wires 50, 52 being opposite to each other. is wound around the small-diameter portion 20 in the direction. Similarly, the second end 50b of the first wire 50 and the first end 54a of the third wire 54 are secured to opposite end portions of the large diameter portion 22 to form the first and third wires. wires 50 and 54 are wound around the large diameter portion 22 in opposite directions.

The operation of this embodiment will be described below with reference to FIGS. 4 to 7. FIG.
When the motor 14 rotates the first winding drum 18 together with the output shaft 16 in the direction of the arrow A1 (clockwise direction), the first wire 50 is wound by the small diameter portion 20 and at the same time from the large diameter portion 22. sent out. At this time, the second wire 52 is sent out from the small diameter portion 20 and the third wire 54 is wound by the large diameter portion 22 .

While the first winding drum 18 rotates, the length of the first wire 50 wound around the small diameter portion 20 is shorter than the length of the first wire 50 sent out from the large diameter portion 22 . Similarly, the length per unit time of the third wire 54 wound by the large diameter portion 22 is longer than the length of the second wire 52 sent out from the small diameter portion 20 . The difference per unit time between the length of the first wire 50 wound around the small diameter portion 20 and the length of the first wire 50 sent out from the large diameter portion 22, and the third wire wound around the large diameter portion 22. Since the difference per unit time between the length of 54 and the length of the second wire 52 sent out from the small-diameter portion 20 is equal, the swing shaft 42 coupled to the rotation shaft 26 by the arms 30 and 32 is 4, together with the rotating shaft 26, it swings about the central axis Oout in the direction of the arrow A1.

When the first winding drum 18 rotates together with the output shaft 16 in the direction of the arrow A2 (counterclockwise direction), the first wire 50 is sent out from the small diameter portion 20 and wound around the large diameter portion 22 at the same time. At this time, the second wire 52 is wound around the small diameter portion 20 and the third wire 54 is sent out from the large diameter portion 22 . As a result, for the reason described above, the swing shaft 42 swings together with the rotation shaft 26 in the direction of the arrow A2 about the central axis Oout, as shown in FIG.

The speed reduction ratio, which is the ratio of the rotational speed of the rotating shaft 26 and the arms 30 and 32 as the output portion to the rotational speed of the motor 14 as the input portion, is the radius of the large diameter portion 22 and the small diameter portion 20 of the first winding drum 18. is proportional to the reciprocal of the difference between Therefore, according to this embodiment, it is possible to determine a substantially infinite number of speed reduction ratios.

Furthermore, since the speed reducer 10 according to the present embodiment does not use gears, there is no sliding friction between meshing gears, the friction during back driving is small, no backlash occurs, and lubrication is unnecessary. and excellent quietness.

Although preferred embodiments of the invention have been described, it will be appreciated by those skilled in the art that the invention is not so limited and that various modifications and improvements are possible. For example, in the above-described embodiment, the first to third wires 50, 52, 54 are wound around the second winding drum 46 attached to the common swing shaft 42. The invention is not limited to this, and the first to third wires 50, 52, 54 may be wound around a plurality of second winding drums.

Referring to FIG. 8, a speed reducer 100 according to a second embodiment of the invention is illustrated. In FIG. 8, components common to or corresponding to those of the speed reducer 10 of FIGS. 1 to 3 are denoted by the same reference numerals, and redundant descriptions of the components will be omitted in the following description.

In the second embodiment, the arms 60 and 62 are each bifurcated and provided with first and second branch portions 60a and 60b: 62a and 62b at the distal ends thereof. First and second swing shafts 64, 66 having winding drums are attached to the first and second branches 60a, 60b: 62a, 62b, respectively. A first wire 50 is wound around the winding drum of the first swing shaft 64 , and second and third wires 52 and 54 are wound around the winding drum of the second swing shaft 66 .

This second embodiment also operates in the same manner as the first embodiment, can determine a substantially infinite number of reduction ratios, has low friction during back driving, does not cause backlash, and furthermore , Lubrication is not required, and it is excellent in quietness.

Furthermore, in the above-described embodiment, the rotary shaft 26 is provided on the cylindrical outer surface of the fixed shaft 24, but the present invention is not limited to this, and the hollow rotary shaft 26 can be rotated around the fixed shaft 24. A supporting structure is not an essential component.

Referring to FIG. 9, a speed reducer 200 according to a third embodiment of the invention is illustrated. In FIG. 9, components common to or corresponding to those of the speed reducer 10 of FIGS. 1 to 3 are denoted by the same reference numerals, and redundant descriptions of the components will be omitted in the following description.

In the third embodiment, the base member for fixing the motor 14 is formed by a housing 70 having a U-shaped cross section, and the output section is a rotating shaft 74 rotatably supported by the housing 70 via bearings 72 and the shaft 74 . It is formed by a pair of arms 76 , 78 coupled to a rotating shaft 74 . In this embodiment, a rotating shaft 74 is directly rotatably supported by a housing 70 as a base member, and the first and second pulleys 34 and 38 are rotatably supported by the rotating shaft 74 .

This third embodiment also operates in the same manner as the first embodiment, can determine a substantially infinite number of reduction ratios, has low friction during back driving, does not cause backlash, and furthermore , Lubrication is not required, and it is excellent in quietness.

REFERENCE SIGNS LIST 10 reduction gear 12 base member 12a hole 14 motor 16 output shaft 18 first winding drum 20 small diameter portion 22 large diameter portion 24 fixed shaft 26 rotating shaft 28 bearing 30 arm 32 arm 34 first pulley 36 bearing 38 second pulley 40 bearing 42 swing shaft 46 second winding drum 48 bearing 50 first wire 50a first end 50b second end 52 second wire 52a first end 52b second end 54 second 3 wire 54a first end 54b second end 60 arm 60a first branch 60b second branch 62 arm 62a first branch 62b second branch 64 first swing shaft 66 second swing shaft 70 housing 72 bearing 74 rotating shaft 76 arm 78 arm 100 reduction gear 200 reduction gear

Claims (1)

In a reduction gear that transmits rotational motion from an input section to an output section,
an input-side rotary shaft forming the input section;
an input-side winding drum provided on the input-side rotating shaft and having a small-diameter portion and a large-diameter portion;
an output-side rotating shaft extending parallel to the input-side rotating shaft and forming the output portion;
a pair of arms coupled to each end of the output-side rotating shaft and extending perpendicularly to the output-side rotating shaft;
A swing shaft extending between the pair of arms and parallel to the input-side rotation shaft and the output-side rotation shaft , coupled to the pair of arms, and swingable around the output-side rotation shaft. and,
a differential winding drum provided on the swing shaft;
A wire stretched between the input side winding drum and the differential winding drum,
the wire
wrapped around the small diameter portion at a first end, around the large diameter portion at an opposite second end, and around the differential winding drum between the first and second ends. a first wire;
a second wire wrapped around the reduced diameter portion at a first end and around the differential winding drum at an opposite second end;
a third wire wrapped around said large diameter portion at a first end and around said differential winding drum at an opposite second end.

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