JP2863529B2 - Rolling ball type transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an improvement of JP-A-62-2064,
In connection with a transmission configured to obtain a large reduction ratio,
In particular, the present invention relates to a rolling ball type transmission designed to be thin in the thickness direction.

[Prior Art] For example, in recent robot technology, a transfer arm whose rotational speed of a motor is lowered by a differential reduction mechanism is rotated. As the differential reduction mechanism, a gear type reduction gear, a cyclo reduction gear, a harmonic drive reduction gear, and the like have been considered to date.

However, a differential reduction mechanism used in robot technology has recently been required to have the following advantages (1) to (5) in order to secure control accuracy. That is, (1) a high reduction ratio can be obtained with a small device.

(2) There is little play such as backlash and the control accuracy is high.

(3) High engagement ratio and high rigidity.

(4) The inertia force of the rotating part is relatively small and the controllability is good.

(5) Low friction and low power loss.

[Problems to be Solved by the Invention] However, the conventional speed reducers described above have advantages and disadvantages, and it is difficult to satisfy all the advantages (1) to (5).

Therefore, the present invention has been made to overcome such difficulties, and the object is to secure a relatively high speed reduction ratio but to be small in size as a whole. It is an object of the present invention to provide an ideal rolling ball type transmission having a high engagement ratio, high rigidity, low friction and low power loss.

[Means for Solving the Problems] The present invention provides a first moving plate having a cycloidal curved guide groove formed on one side surface along a base circle, and a first moving plate having a guide groove formed on the first moving plate. A second moving plate that is arranged in a face-to-face state and on one side of which is formed a cycloid-based curved guide groove along a base circle; and a second moving plate that is arranged so as to extend over both of the first and second moving plates. A rolling ball that rolls along the two guide grooves by relative rotation of the first moving plate with respect to the second moving plate, and causes the first moving plate to perform rotational displacement and revolving displacement;
The first moving plate and the stationary member are provided between the first moving plate and the stationary member.
And a correcting means for absorbing the revolving displacement of the moving plate and transmitting only the rotational displacement to the second moving plate, wherein the correcting means comprises: Linear grooves formed in directions perpendicular to each other on the front and back sides of the correction plate disposed between the stationary member and linear grooves formed in the stationary member corresponding to the grooves on the back surface of the correction plate. A linear groove formed on the side opposite to the guide groove of the first moving plate so as to correspond to a groove on the surface of the correction plate; and a groove of the first moving plate and the correction. A rolling element provided between the groove of the plate and between the groove of the stationary member and the groove of the correction plate so as to move along each of the grooves, wherein the correction plate is The rolling element moves in a state where the rolling element is in contact with each of the grooves by being pressed between a moving plate and the stationary member. And it features.

[Operation and Effect of the Invention] According to the present invention configured as described above, the transmission mechanism is arranged by arranging the first and second moving plates to face each other so that the rolling balls are inserted into both grooves. As a result, the overall size is small and there is no backlash,
High precision in control is obtained, the meshing ratio is improved, the inertia of the rotating part is small, and in this respect, the controllability is good, and the friction is small and the power loss is small.

Also, when the second moving plate is transmitted in rotation, the revolving displacement that occurs is performed by the groove in which the correcting plate and the rolling element are inserted.
The grooves are straight and easy to machine.

In addition, even if the correction plate is firmly sandwiched between the stationary member and the first moving plate and the rolling element comes into strong contact with the groove, the displacement of the rolling element with respect to the groove is maintained in a smooth state and there is no torque loss. There is no torque ripple.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. 1
Is a disk-shaped stationary member, in which a bearing 2 is fitted at the center thereof, and three rows of grooves 1a and 1b are formed on one side surface of the stationary member, which face each other in the radial direction with the bearing 2 interposed therebetween. Reference numeral 3 denotes a correction plate having a through hole 4 formed in the center, which is located facing the stationary member 1,
On one side surface, grooves 3a, 3b for grooves 1a, 1b are formed, and steel balls St as rolling elements are put in these grooves 1a, 1b and grooves 3a, 3b in a contact state shown in FIG. .

On the other side of the correction plate 3, grooves 3c, 3d facing the grooves 3a, 3b are formed so as to be orthogonal to the grooves 3a, 3b.
Reference numeral 5 denotes a first moving plate in which a bearing 6 is fitted in the center. On one side surface of the first moving plate, grooves 4a and 4b opposed to the grooves 3c and 3d are formed, and these grooves 3c and 3d and grooves 4a and 4b are formed. Has a steel ball St as a rolling element in the same contact state as in FIG. Reference numeral 7 denotes a second moving plate having a bearing 8 fitted in the center thereof, which is a first moving plate 5.
The output shaft 9 is integrally formed on the side opposite to the facing side. Reference numeral 10 denotes an eccentric shaft, which is an eccentric portion 10a, a large-diameter portion 10b, and a semilunar shoulder as shown in FIG.
10c and an input portion 10d, the eccentric portion 10a is supported by the bearing 8, and the large-diameter portion 10b is supported by the bearing 6,
The input portion 10d is supported by the bearing 2 by bringing the shoulder portion 10c into frictional contact with the inner peripheral edge of the through hole 4.

By the way, the surface of the first moving plate 5 is described in Japanese Patent Application Laid-Open No. 62-2064.
Guide groove having a substantially semicircular cross section as described in Japanese Patent Publication
11 are formed. The guide groove 11 is continuously formed on a predetermined pitch circle with ten wave numbers according to an epicycloid curve. Further, a guide groove 12 having a substantially semicircular cross section is formed on a surface of the second moving plate 7 facing the first moving plate 5.
Are formed. The guide groove 12 has a continuous shape on a pitch circle having the same dimensions as described above with 12 wave numbers according to a hypocycloid curve. Here, the epicycloid curve and the hypocycloid curve are curves drawn when each is moved with a predetermined diameter, and the wave height dimension is defined as the amount of eccentricity. Reference numeral 13 denotes a rolling ball made of steel, for example, which is provided one number greater than the wave number 10 of the guide groove 12, that is, 11 balls, and the first and second moving plates 5,
7 are arranged at equal intervals inside the guide grooves 11 and 12, and roll along the guide grooves 11 and 12 as the second moving plate 7 rotates.

When the above configuration is applied to a transfer robot, a motor (not shown) is connected to the input unit 10d of the eccentric shaft 10, and a transfer arm (not shown) is connected to the output shaft 9. Is attached. When the motor is driven, the eccentric shaft 10 rotates, and the eccentric portion 10a causes the second moving plate 7 to rotate.
The eccentric rotational force accompanied by the rotation and the revolving displacement is about to be transmitted.

At this time, the first moving plate 5 can be moved in the y-axis direction by a steel ball St inserted between the grooves 4a and 4b and the grooves 3c and 3d, and the grooves 1a and 1b and the grooves 3a and 3b The steel ball St inserted between them allows movement in the x-axis direction. Therefore, the revolving displacement component of the eccentric rotational force transmitted to the second moving plate 7 is absorbed by the displacement in the x-axis and y-axis directions, and only the rotational displacement is transmitted to the second moving plate 7. As a result, the arm of the output shaft 9 is rotated and displaced by a predetermined angle.

In this case, one rotation of the eccentric shaft 10 corresponds to an amount of moving the guide grooves 11 and 12 of the rolling ball 13 by the length of two wavenumbers. Moving plate 5
And the ratio to the numerical value obtained by adding the number 2 to the wave number N of the guide groove 11, ie, 2 / (N + 2). In the above embodiment, since the wave number N of the guide groove 11 is 10, the reduction ratio is 2 / (10 + 2) = 1/6.

As described above, the first moving plate 5 and the second moving plate 7 need only be provided in parallel in a state of facing each other while maintaining a relatively high reduction ratio of 1/6, so that they are short in the left-right direction. Thin and small overall.

Further, since the first moving plate 5 and the second moving plate 7 are connected to each other by the rolling balls 13 via the guide grooves 11 and 12, these first and second moving plates 5 and 7 are connected. The gap between them can be removed, and the rotation angle of the output shaft 9 can be set with high accuracy.

In addition, since the first moving plate 5 and the second moving plate are securely connected by the rolling balls 13 via these guide grooves 11, 12, the first and second moving plates 5, 7 are integrated and have high rigidity, while the rolling balls 13
Since it is provided in close contact without rattling, not only play such as backlash is eliminated, but also the meshing ratio is increased.

Furthermore, since the first and second moving plates 5 and 7 themselves need only be relatively thin, their inertial force is reduced and controllability is improved.

In addition, since the friction between the guide grooves 11, 12 and the rolling balls 13 is small, the rotation speed can be efficiently displaced, and the power loss is small.

Moreover, the groove 1 for absorbing the revolution displacement component of the second moving plate 7
The grooves a, 1b, the grooves 3a, 3b, the grooves 3c, 3d and the grooves 4a, 4b may have a straight shape, which facilitates processing, and furthermore, the correction plate 4 is firmly provided between the stationary member and the first moving plate 5. Even if a load such as being pinched is received, the steel ball St is smoothly displaced along the groove, so that torque loss and torque ripple are also eliminated. In addition,
In the above embodiment, the steel balls St are individually separated, but a retainer that holds the steel balls St collectively may be used.

 Further, the rolling elements may be rollers.

Further, these balls may be formed of a material having high wear resistance such as ceramic.

In addition, various changes can be made in concrete implementation without departing from the gist of the invention.

[Brief description of the drawings]

1 to 3 show a first embodiment of the present invention.
The figure is an exploded perspective view of the whole, FIG. 2 is an explanatory view of the shape of the groove, and FIG.
The figure is an overall longitudinal sectional view. In the drawing, 1 ... stationary member, 1a, 1b ... groove, 3a, 3b, 3c, 3d
... groove, 4a, 4b ... groove, 5 ... first moving plate, 7 ... second
No. of moving plates, 11, 12 …… Guide groove 13 …… Rolling ball, St …… Steel ball (rolling element)

Claims (1)

(57) [Claims] A first moving plate having a guide groove having a cycloidal curved shape along a base circle on one side; a first moving plate facing the side where the guide groove is formed on the first moving plate; A second moving plate having a cycloidal curved guide groove formed along the base circle, and a second moving plate which is disposed so as to extend over both the guide grooves of the first and second moving plates. A rolling ball that rolls along the two guide grooves due to relative rotation with respect to the moving plate and causes the first moving plate to perform rotational displacement and revolving displacement; and provided between the first moving plate and a stationary member. This first
And a correcting means for absorbing the revolving displacement of the moving plate and transmitting only the rotational displacement to the second moving plate, wherein the correcting means comprises: Linear grooves formed in directions perpendicular to each other on the front and back sides of the correction plate disposed between the stationary member and linear grooves formed in the stationary member corresponding to the grooves on the back surface of the correction plate. A linear groove formed on the side opposite to the guide groove of the first moving plate so as to correspond to a groove on the surface of the correction plate; and a groove of the first moving plate and the correction. A rolling element provided between the groove of the plate and between the groove of the stationary member and the groove of the correction plate so as to move along each of the grooves, wherein the correction plate is The rolling element is moved in a state where the rolling element is in contact with each of the grooves by being pressed between a moving plate and the stationary member. A rolling ball type transmission characterized by the following.