JPS6360260B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a speed reduction device in which rolling elements are driven;
In particular, the present invention relates to a speed reduction device suitable for a drive mechanism of, for example, an industrial robot, which performs high-speed, high-precision positioning based on position commands from a computer.

[Background of the invention]

A conventional reduction gear device includes a fixed annular body having an internal gear and an elastically deformable annular body having an external gear that meshes with the internal gear, and uses the difference in the number of teeth between these to obtain a reduction ratio. There is something I did. This type of speed reduction device has a US Patent No.
There is one described in No. 2906143.

In this type of reduction gear, the annular body is configured to be elastically deformable in order to mesh the external gear of the annular body with the internal gear of the fixed annular body. Since this annular body has a structure that can be elastically deformed, when this reduction gear device is used in a drive mechanism system, the rigidity of this drive mechanism system is reduced. Particularly when used in a machine such as an industrial robot that performs highly accurate position control in response to commands, the natural frequency of the machine becomes low, positioning accuracy deteriorates, and high-speed operation becomes impossible. Furthermore, since the teeth of this type of reduction gear mesh with each other while sliding, there is a drawback that the friction loss is large and the power transmission efficiency is low.

[Purpose of the invention]

The present invention has been made based on the above-mentioned matters, and an object of the present invention is to provide a speed reduction device having high rigidity and good transmission efficiency.

[Summary of the invention]

The present invention is characterized by a cam connected to an input shaft, a plurality of supporting rolling elements in contact with the cam surface, an annular body in contact with the supporting rolling elements, and a deceleration means connected to the annular body. In a speed reduction device that transmits the speed of an input shaft to an output shaft, the speed reduction means is provided on the inner circumference of the casing and contacts an internally toothed body having teeth arranged at equal intervals and having an inclined surface, and the outer circumference of the annular body. A drive rolling element that has more teeth than the internal toothed body and rolls along the tooth surface of the internal toothed body, and a drive rolling element that is held at equal intervals and connected to the output shaft. The reason is that it is constructed with a holder that has a

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show an embodiment of the reduction gear of the present invention. In these figures, 1 is an annular casing, and 2 and 3 are covers provided on the side surfaces of the casing 1. FIG. The covers 2 and 3 are fixed to the casing 1 with bolts 4.
5 is an input shaft that is rotatably supported by the cover 2 by a bearing 6, 7 is an output shaft that is rotatably supported by the cover 3 by a bearing 8, and this output shaft 7 is connected to the input shaft 5.
is placed concentrically with the axis of An internal gear body 10 having equally spaced teeth 9 is integrally provided on the inner periphery of the casing 1 described above. This internal tooth body 10
As shown in FIG. 2, tooth surfaces 11A and 11B forming a tooth groove G having a triangular cross section are provided between the teeth 9 and 9. The teeth 9 of the internal gear body 10 are provided with a plurality of drive rolling elements 1 that roll and move along the teeth 9 and the tooth grooves.
2 is placed. The number of driving rolling elements 12 is
2n, the number of teeth 9 on the internal tooth body 10 is 2(n-
1) Selected as In this example n=13
It is shown as. The driving rolling element 12 is a holding body 13
They are inserted and held in the grooves 13A and arranged at equal intervals in the circumferential direction. The holder 13 is rotatably supported on the inner surface of the casing 1 by a bearing 14. This holding body 13 is connected to the end of the output shaft 7 inside the casing 1 by a disk-shaped connecting body 15. The end of the input shaft 5, which is arranged concentrically with the output shaft 7, is provided with a cam 16. Cam surface 16 of this cam 16
A plurality of roller-shaped support rolling elements 17 are arranged in contact with A. Around the outside of this supporting rolling element 17, a flexible annular body 1 is placed in contact with the supporting rolling element 17.
8 is provided. The outer peripheral surface of this annular body 18 contacts the drive rolling element 12 described above. The annular body 18, the support rolling element 17, and the cam 16 constitute a means 19 (hereinafter referred to as a wave generator) that provides periodic displacement motion to the drive rolling element 12 around the input shaft. The support rolling element 17 is restrained from moving in the axial direction by a side plate 20 provided on the side surface of the cam 16.

As mentioned above, the number of drive rolling elements 12 arranged around the axes of the input shaft 5 and output shaft 7 is
2n teeth (in this example, 24 teeth are shown), while the number of teeth 9 on the internal tooth body 10 is 2(n-1).
(in this example, 26 pieces are shown). Therefore, the number (n) of the half circumference of the driving rolling element 12 is one more than that of the teeth 9 of the internal toothed element 10, so if the pitch of the teeth 9 of the internal toothed element 10 is p, then the driving rolling element The position of the tooth 12 is shifted by p/n with respect to one pitch p of the tooth 9. Therefore, counting from a certain reference tooth 9, the m-th driving rolling element 12
are out of phase by p/n×m. Then, the position is symmetrical with respect to the center point of the input shaft 5, that is, 180
At the positions far apart, the driving rolling elements 12 are out of phase with respect to the teeth 9 by one pitch p.

The shape of the cam surface 16A of the cam 16 described above is selected as shown in FIG. That is, the cam surface 16A of the cam 16 has a reference circle having a diameter R ₀ and n of the tooth pitch angle α on this reference circle.
It is formed by an arc set by the amount of radial displacement R (θ) of the driving rolling element 12 added outward from the reference circle within the range of double the angle θ (=αn). . The detailed displacement amount setting of this cam surface 16A will be described later.

Next, the operation of one embodiment of the above-described apparatus of the present invention will be described.

Now, as shown in FIG. 4, when the input shaft 5 rotates the cam 16 in the direction of arrow A, the drive rolling element 12B on the right side of the reference drive rolling element 12A in FIG. Since the position of the teeth 9 of the tooth body 10 is shifted by 1/n of one pitch p, when the cam 16 is rotated by one pitch p, the drive rolling element 12B is pushed to the bottom of the teeth 9. At this time, since the driving rolling element 12B moves in the circumferential direction by p/n, the holding body 13 holding the driving rolling element 12 is rotated clockwise by p/n. This rotation of the holding body 13 is controlled by the output shaft 7 via the connecting body 15.
transmitted to.

When the cam 16 is rotated by half a rotation as shown in FIG. 5, the drive rolling element 12A moves to the adjacent tooth 9 relative to the state shown in FIG. 4, so that the holder 13 rotates by 1/n. Furthermore, when the cam 16 rotates once, the drive rolling element 12 moves by two teeth of the teeth 9, so the holder 13 rotates by 2/n, so the output shaft 7 is rotated by 2/n with respect to the input shaft 5. Rotates with a reduction ratio of /n.

In order to obtain the aforementioned deceleration operation, the driving rolling elements 1
2 moves along the tooth 9 and the tooth groove G of the internal tooth body 10, and its movement locus will be explained with reference to FIG. In this figure, parts with the same reference numerals as in FIGS. 1 and 2 are the same parts. Curve X is driving rolling element 1
The curve Y shows the locus of movement of the center Ox of No. 2 along the tooth 9 and the tooth groove G, and the curve Y shows the locus of movement of the tangent point Oy between the annular body 18 and the driving rolling element 12. This curve Y is exactly the same as the curve X, with the only difference being the amount of displacement corresponding to the radius of the drive rolling element 12. As is clear from this figure, cam 1
6, the driving rolling element 12 rotates in the direction of arrow A.
It moves to the right along the upper tooth 9 in the drawing as shown by the dotted chain line.

Next, the operation of the wave generator 19 for displacing the drive rolling element 12 in the radial direction with respect to the axis of the input shaft 5 will be explained with reference to FIG. This figure is an expanded view of the displacement R(θ) of the cam surface 16A of the cam 16. Now, set cam 16 to 1
When the cam surface 16A is rotated by pitch p [=360°/2(n-1)], the displacement amount R(θ) of the cam surface 16A changes from the state shown by the solid line to the state shown by the dotted line. Due to this shift of the cam surface 16A, the drive rolling element 12 has teeth 9, 9.
It is pushed into or pushed out from the tooth groove G at the position of the tooth groove G in between. The downward arrow in FIG. 7 indicates the displacement in the direction in which the driving rolling element 12 is pushed out of the tooth groove G, and the upward arrow indicates the displacement in the direction in which the driving rolling element 12 is pushed into the tooth groove G.

The movement of the holding body 13 caused by the movement of the driving rolling element 12 into and out of the tooth space G will be described in more detail.

When the drive rolling element 12 receives the displacement shown by the upward arrow in FIG. 7 by the wave generator 19, the drive rolling element 12 moves one pitch p [=360 /2
(n-1)] is pushed into the tooth groove G by the distance shown by the arrow R in the radial direction. At this time, the drive rolling element 12 rolls along the inclined tooth surface 11A and moves by a distance indicated by arrow C in the circumferential direction.
Since the driving rolling element 12 is in contact with the holding body 13,
The holder 13 is moved in the circumferential direction by a distance indicated by arrow C. Next, when the drive rolling element 12 is displaced by the wave generator 19 as indicated by the downward arrow in FIG.
moves by C in the circumferential direction, the driving rolling element 12
can be pushed out from the tooth groove G by R along the slope of the tooth surface 11B. At this time, since the wave generator 19 has already been displaced by R, the drive rolling element 12 can be easily pushed out from the tooth space G.

Next, the relationship between the acting forces when the drive rolling element 12 moves into and out of the tooth space G will be explained.

When the displacement shown by the downward arrow in FIG. 7 is applied, when force S is applied to the drive rolling element 12 by the annular body 18 of the wave generator 19 as shown in FIG. A reaction force T corresponding to Q and the sliding frictional force μQ is received from the tooth surface 11A of the tooth 9 and is balanced. The force Q described above becomes the transmission driving force of the reduction gear of the present invention. When the wave generator 19 rotates in the direction of the arrow in FIG.
Since there is a slippage between A and A, a frictional force is generated in this part. Next, when the displacement shown by the downward arrow in FIG. 7 is applied, the force f from the holder 13 and the force e from the tooth surface 11B of the tooth 9 are applied to the drive rolling element 12 as shown in FIG. The resultant force j acts on the tooth and pushes it out of the tooth space G. These forces are only enough to push the drive rolling element 12 out of the tooth space G, and therefore have extremely small values.

It is desirable that the plate thickness t of the aforementioned holder 13 be approximately 1/2 or more of the diameter D of the drive rolling element 12, as shown in FIG. If t=1/2D is selected, when the drive rolling element 12 is pushed into the tooth groove G by the holder 13, the driving force Q and sliding friction force μQ of the drive rolling element 12 will be 13A
Concentrate on the edges. This causes friction and plastic deformation at this end. Further, when t<1/2D is selected, a force including a radial component acts on the end of the groove 13A of the holder 13, and the holder 1
3 deforms or causes vibration. Furthermore, when pushing out the drive rolling element 12 from the tooth space G, the holding body 13
Since the force acting on the driving rolling element 12 from the end of the groove 13A and the force acting on the driving rolling element 12 from the tooth surface are directed toward the center of the driving rolling element 12, the driving rolling element 12 is in a locked state. A jamming phenomenon occurs, and the holding body 13 becomes unable to move in the circumferential direction. For these reasons, the plate thickness t of the holder 13 is preferably selected to satisfy t≧1/2D.

As described above, the drive rolling elements 12 are arranged symmetrically about the center point of the input shaft 5. For this reason, the seventh
The acting portion indicated by the upward arrow in the diagram, that is, the driving rolling element 12 that generates the driving force, is point symmetrical as shown in FIG. 12. With this arrangement, the force S that forces the drive rolling element 12 into the tooth space G is in the opposite direction and is canceled out inside the wave generator 19. Therefore, only pure torque can be extracted. If the input shaft 5 and the wave generator 19 are not configured in this way, a large bending moment will act on the input shaft 5 and the wave generator 19, causing deformation and damage to each part.

Moreover, although the above-mentioned tooth groove G has been described as having a triangular shape, other shapes can be used.
That is, when the shape of the tooth groove G is formed into a waveform W as shown in FIG. 13, the movement locus of the center point of the drive rolling element 12 rolling on the tooth is Rw(α)
become that way. If the cam 16 shown in FIG. 3 is created based on this movement locus Rw(α), all the driving rolling elements 12 can be smoothly rolled along the wave-shaped teeth 9A. Therefore, since the shape of the wave generator 19 can be easily determined according to the shape of the teeth, the tooth shape can be freely selected. However, if the slope of the tooth surface of the tooth groove is steep, when pushing the drive rolling element 12 out of the tooth groove G, the reaction force will pass near the center point of the drive rolling element 12. It becomes easier to lock, and if the slope of the tooth surface is gentle, the drive transmitted to the holder 13 becomes smaller. For this reason, the angle of inclination of the central portion of the tooth surface is preferably selected to be approximately 45°.

The annular body 18 and the supporting rolling element 17 described above absorb the relative sliding motion between the cam 16 and the driving rolling element 12 that occurs due to deceleration as rolling motion. If the reduction ratio is not large, the above-mentioned relative sliding motion is small, so it is not necessary to use the annular body 18 and the supporting rolling elements 17.

Further, as described above, the holding body 13 has rigidity and also has a small length in the axial direction, so that the axial dimension of the reduction gear device can be reduced.

〔Effect of the invention〕

As described above, according to the present invention, deceleration is obtained by rolling the driving rolling elements along the tooth profile, so that it is possible to provide a deceleration device with high rigidity and high power transmission efficiency. It is something that can be done.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view showing an embodiment of the reduction gear device of the present invention, Fig. 2 is a sectional view taken along the - arrow in Fig. 1, and Fig. 3 is an example of the shape of a cam used in the device of the present invention. 4 and 5 are cross-sectional views illustrating the deceleration operation of the device of the present invention, and FIG. 6 is a diagram illustrating the engagement operation between the driving rolling element and the tooth groove that constitute the device of the present invention. , FIG. 7 is a developed view showing the amount of displacement of the driving rolling elements constituting the device of the present invention, and FIGS. 8 and 9 are
The figures are explanatory diagrams showing the moving relationship between the drive rolling element and the holding body constituting the device of the present invention, Figure 10 and Figure 1.
Fig. 1 is an explanatory diagram showing the force relationship acting between the driving rolling element and the holding body, Fig. 12 is a cross-sectional view showing the driving force generation situation in the device of the present invention, and Fig. 13 is an explanatory diagram showing the force relationship acting between the driving rolling element and the holding body. It is a figure which shows the other tooth profile shape of the internal gear body used. 1... Annular casing, 2, 3... Cover,
5...Input shaft, 7...Output shaft, 9...Teeth, 10...
... Internal gear body, 11A, 11B ... tooth surface, 12 ... drive rolling element, 13 ... holding body, 13A ... its groove,
16...cam, 16A...its cam surface, 17...
Support rolling element, 18... annular body.

Claims (1)

[Scope of Claims] 1. An annular casing, an input shaft supported by the casing via a bearing, a cam connected to the input shaft, and a plurality of supporting rolling elements in contact with the cam surface of the cam, In the reduction gear device, which includes an annular body in contact with the supporting rolling element and a deceleration means connected to the annular body, the deceleration device reduces the speed from the input shaft and transmits it to the output shaft. an internal tooth body provided with teeth arranged at equal intervals and having an inclined surface, and in contact with the outer periphery of the annular body, the number of teeth being greater than the number of teeth of the internal tooth body,
A speed reducer characterized by comprising a drive rolling element that rolls along the tooth surface of the internal toothed body, and a holder that holds the drive rolling element at equal intervals and is connected to the output shaft. Device. 2. The speed reduction device according to claim 1, wherein the internal toothed body has two or more teeth less than the number of the driving rolling elements. 3. The speed reduction device according to claim 1, wherein the cam, the support rolling element, and the annular body give the driving rolling element periodic displacement motion in the circumferential direction around the input shaft. . 4. The speed reduction device according to claim 1, wherein the thickness of the holding body is larger than half the diameter of the driving rolling element.