JP2828546B2 - Inner mesh planetary gear structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internally meshing planetary gear structure suitable for a small reduction gear or a speed increasing gear, and more particularly to a toothed structure.

[0002]

2. Description of the Related Art Conventionally, a first shaft, an eccentric body rotated by rotation of the first shaft, a plurality of external gears mounted on the eccentric body via bearings and capable of eccentric rotation,
An internal gear internally meshed with the external gear via internal teeth formed of external pins, and a second internal gear connected to the external gear via an internal roller for extracting only a rotation component of the external gear. Axis and
A double-row internal meshing planetary gear structure provided with a gear is widely known.

FIGS. 6 and 7 show a conventional example of this structure.
In this conventional example, the first shaft is used as an input shaft and the second shaft is used as a second shaft.
The above structure is applied to a "reduction gear" by using a shaft as an output shaft and fixing an internal gear.

The input shaft 1 has a predetermined phase difference (18 in this example).
0 °), the eccentric bodies 3a, 3b are fitted. The eccentric bodies 3a and 3b are respectively connected to the input shaft 1 (center O1).
(Center O2). Two external gears 5a, 5b are attached to the respective eccentric bodies 3a, 3b in double rows via bearings 4a, 4b. The internal gear holes 6a, 6b are provided in the external gears 5a, 5b.
b are provided, and the inner pin 7 and the inner roller 8 are fitted therein.

The reason why the number of external gears is two (double row) is as follows.
This is mainly to increase transmission capacity, maintain strength, and maintain rotational balance.

[0006] On the outer periphery of the external gears 5a and 5b, external teeth 9 having a trochoid tooth shape (epitrochoid parallel curve tooth shape) are provided. The external teeth 9 are internally meshed with an internal gear 10 fixed to a casing 12.

The inner pin 7 penetrating the external gears 5a, 5b is fixed or fitted to the flange of the output shaft 2.

When the input shaft 1 makes one rotation, the eccentric bodies 3a, 3b
Makes one revolution. By one rotation of the eccentric bodies 3a and 3b,
Although the external gears 5a and 5b try to oscillate around the input shaft 1, their rotation is restricted by the internal gear 10, so that the external gears 5a and 5b Mostly only swinging while touching.

Now, for example, the number of teeth of the external gears 5a and 5b is set to n.
(In the illustrated example, n = 21), the internal gear 10
Is n + 1, the difference N between the teeth is 1.
Therefore, for each rotation of the input shaft, the external gears 5a and 5b
As a result, the internal gear 10 is shifted (rotates) by one tooth with respect to the internal gear 10 fixed to the casing 12. This is input shaft 1
Is reduced to -1 / n rotation of the external gears 5a, 5b.

The rotation of the external gears 5a and 5b is absorbed by the gap between the inner roller holes 6a and 6b and the inner pin 7 (the inner roller 8), and only the rotation component is absorbed by the inner pin 7
To the output shaft 2.

As a result, deceleration with a reduction ratio of -1 / n is achieved.

Incidentally, this internal meshing planetary gear structure is currently applied to various reduction gears or speed increasing gears. For example, in the above structure, the first shaft is used as the input shaft, the second shaft is used as the output shaft, and the internal gear is fixed. However, the first shaft is used as the input shaft, and the internal gear is used as the output shaft. Along with
The speed reducer can also be configured by fixing the second shaft. Further, in these structures, by reversing the input and output shafts, a "speed increasing device" can be configured.

In this type of internally meshing meshing planetary gear structure, the applied load is generally determined by the magnitude of the contact pressure on the tooth surface, which limits the miniaturization and high load capacity of the device. Therefore, reduction of the surface pressure of the tooth surface has been particularly required.

Therefore, conventionally, as shown in JP-B-63-4056, the tooth profile of the external gear 9 of the external gear has an epitrochoid parallel curve (see FIG. 9), and the tooth profile of the internal gear 11 of the internal gear has the trochoid internal gear. By using the envelope (see FIG. 10), the mesh point (contact point) of each tooth of the external gear and the internal gear can be set to two.
There have been proposed ones that reduce the surface pressure on the tooth surface by increasing the number of points.

Specifically, in this technology,
As shown in FIG. 8, the tooth profile of the external teeth 9 of the external gears 5 a and 5 b is configured by an epitrochoid parallel curve, and the tooth profile of the internal tooth 11 of the internal gear 10 is set to the intermediate between the arcuate tooth profile portions P and P at both ends. (This portion is a tooth profile obtained as a mating tooth profile when the tooth profile of the external tooth is formed by an epitrochoid parallel curve) is constituted by a trochoid internal envelope.

According to the gear structure employing this tooth profile, at the meshing portion between the internal gear 10 and the external gears 5a and 5b, the two contact points (meshing points) are two effective positions for transmitting the load. . That is, in addition to the contact point of the arc tooth part P, the tooth part Q has a contact point. Since these two contact portions both satisfy the conditions of the mechanical tooth profile of the gear, each contact point effectively acts on power transmission.

As described above, in the internal meshing planetary gear structure of the above-mentioned conventional publication, two-point contact of the teeth is made possible by improving the tooth profile, thereby reducing the surface pressure on the tooth surface, thereby reducing the size.
High load capacity is being achieved.

[0018]

However, even if the above-mentioned tooth profile is used, the load capacity of the tooth surface is still limited, and in order to further reduce the size and weight of the reduction gear, a further reduction in the tooth surface is required. High load capacity is required.

The present invention has been made in view of such a conventional problem, and has a tooth shape in which the difference in the number of teeth is two or more, and in this case, two-point contact between the external teeth and the internal teeth is possible. It is an object of the present invention to provide a lightweight, compact and high-performance internally meshing planetary gear structure.

[0020]

SUMMARY OF THE INVENTION According to the present invention, there are provided a first shaft and a plurality of outer shafts mounted eccentrically rotatable with respect to the first shaft via an eccentric body provided on the first shaft. An internal gear comprising: an external gear, an internal gear in which the external gear meshes internally, and a second shaft connected to the external gear via means for transmitting only the rotation component of the external gear. In the meshing planetary gear structure, a difference in the number of teeth between the external gear and the internal gear is N (N: an integer of 2 or more), and the tooth profile of the external gear is shifted by N epitrochoid parallel curves. The inner gear is formed by the innermost curve formed when superimposed, and the tooth profile of the internal gear is shifted by the same number of phases as the external gear by N trochoid internal envelopes meshing with the epitrochoid parallel curve. that have configured <br/> by the most inside of the curve can be when superimposed Te It is obtained by solving the above problems. What
When configuring the actual tooth profile, the external teeth and the internal teeth
Appropriately rounded tip or root)
It is of course not prohibited to make corrections such as
In addition, those which have performed such processing naturally fall within the category of the present invention.
include.

[0021]

In the gear structure of the present invention, the difference in the number of teeth between the external gear and the internal gear is set to N (an integer of 2 or more). When the same reduction ratio as in the case of the tooth number difference 1 is obtained, the number of teeth of the external gear and the internal gear should be N times that of the conventional gear. it can. This allows
The number of meshing teeth in a portion effective for load transmission increases, and the meshing of a portion that does not work effectively in power transmission and has a large slip can be reduced. Therefore, the contact pressure at the contact point can be reduced, and the power transmission loss can be reduced.

On the other hand, Japanese Patent Publication No. 63-4056 mentioned above
This is a technique when the tooth number difference N is 1, and when the tooth number difference N is 2 or more, it is difficult to apply this as it is in the case of a tooth number difference of 2 or more. In view of this point, in the present invention, the external gear and the internal gear make two-point contact at a position effective for load transmission even when the difference in the number of teeth N is 2 or more by employing the above-described configuration. It is.

[0023]

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

In the gear meshing structure of the embodiment, the external teeth (reference numeral 1)
9 is different from the conventional one only in the tooth profile of the internal tooth (indicated by reference numeral 111) and the tooth profile of the internal teeth (indicated by reference numeral 111).
The same configuration as that shown in FIG. Therefore, in the following, the tooth profile of the external teeth 109 and the tooth profile of the internal teeth 111 will be mainly described, and other descriptions will be omitted.

In this embodiment, the number of teeth of the external gears 5a and 5b is 42, the number of teeth of the internal gear 10 is 44, and the difference between the numbers of teeth is 2.

As shown in FIG. 2, the tooth profile of the external teeth 109 of the external gears 5a and 5b is the innermost shape when two epitrochoid parallel curves are overlapped with each other with a phase shifted by 1/2 of one tooth. The curve is composed of

The tooth profile of the internal teeth 111 of the internal gear 10 is as follows.
It is constituted by the innermost curve when two trochoid inner envelopes including arcuate teeth at both ends described in the prior art are overlapped with each other with a phase shifted by の of one tooth.
The internal teeth 111 are formed integrally with the body material of the internal gear 10 instead of the pins.

Here, "inside" means the external gear 5a,
5b or “center side” of the internal gear 10.

In the above, the external teeth 109 and the internal teeth 111
The curve that is the basis of the superposition of
It is a tooth profile curve (refer FIG. 9, FIG. 10) of the external tooth and the internal tooth shown by 4056. About the internal teeth 111, specifically,
When the difference between the number of teeth of the external gear and the number of teeth of the internal gear is 1, the envelope formed by the external teeth composed of the epitrochoid parallel curve is basically used.

Here, these curves are compared with each other by 1 / tooth of one tooth.
The reason why the two are superposed with the phase shifted by two is that the difference in the number of teeth between the external gear and the internal gear is two. If the difference in the number of teeth is three, the innermost curve obtained by superimposing three curves whose phases are shifted from each other by ３ of one tooth is defined as a tooth profile curve. If the difference in the number of teeth is greater,
The same number of curves are overlapped to obtain a similar tooth profile curve.
When the difference in the number of teeth is 2, the way in which the two curves are shifted does not necessarily have to be の of one tooth, but even in this case, the way of shifting the external gear and the internal gear is the same (shift). Same amount)
Must be.

In the case of forming an actual tooth profile, the external teeth 1
Modification such as appropriately rounding the tip or root of 09 and the internal teeth 111 may be performed.

With the tooth profile of the external teeth 109 and the internal teeth 111 configured in this manner, the external teeth 10 of the external gears 5a and 5b are formed.
9 and the internal teeth 111 of the internal gear 10 are described in JP-B-63-405.
As in the gear of the device described in Japanese Patent Application Laid-Open No. 6-206, two points contact (mesh) at a position effective for load transmission. FIG. 4 and FIG.
In the gear meshing structure of the present embodiment, the meshing state of the external teeth 109 and the internal teeth 111 when the eccentric bodies 3a and 3b are rotated is shown.

In this gear structure, when the input shaft 1 makes one rotation, the eccentric bodies 3a and 3b make one rotation. This eccentric 3
Although the external gears 5a and 5b attempt to oscillate around the input shaft 1 by one rotation of the external gears 5a and 5b, the rotation of the external gears 5a and 5b is restricted by the internal gear 10.
Performs almost only swing while inscribed in the internal gear 10.

In this embodiment, the number of teeth of the external gears 5a and 5b is four.
2. The number of teeth of the internal gear 10 is 44, and the difference in the number of teeth is 2
Therefore, each time the input shaft 1 rotates, the external gears 5a, 5a
b shifts (rotates) by two teeth with respect to the internal gear 10 fixed to the casing 12. this is,
This means that one rotation of the input shaft 1 has been reduced to -1/21 rotation of the external gears 5a and 5b.

The rotation of the external gears 5a and 5b is absorbed by the gap between the inner roller holes 6a and 6b and the inner pin 7 (the inner roller 8), and only the rotation component is reduced.
To the output shaft 2. As a result, deceleration with a reduction ratio of -1/21 is achieved.

Here, considering the case where the same reduction ratio (-1/21 in this example) is obtained between the prior art and the present embodiment, the number of teeth of the external gears 5a, 5b and the internal gear 10 is as follows. 21 and 22 in the case of the prior art, and 42 and 44 in the case of the present embodiment, respectively.
The number of teeth is doubled in the present invention. Therefore, the number of meshing teeth in a portion effective for load transmission is doubled, and meshing in a portion that does not work effectively in power transmission and has large slippage can be eliminated. Therefore, it is possible to improve the load capacity of the gear (the strength of the gear and the resistance to scoring), and as a result, it is possible to reduce the weight and size of the reduction gear.

[0037]

As described above, according to the internal meshing planetary gear structure of the present invention, even if the difference in the number of teeth between the external teeth of the external gear and the internal teeth of the internal gear is two or more, the two An engagement point can be secured. For this reason, the load per tooth due to the increase in the number of teeth can be reduced while reducing the surface pressure on the tooth surface, and as a result, the strength of the gear can be improved, and the weight, compactness, and height can be reduced. A high-performance reducer or speed-up gear can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of an embodiment of the present invention, and FIG.
Sectional view corresponding to the section taken along line VII-VII of FIG.

FIG. 2 is an enlarged view of a tooth profile of an external gear of the external gear in the same embodiment (one obtained by superposing epitrochoid parallel curves).

FIG. 3 is an enlarged view of the tooth profile of the internal gear of the internal gear in the embodiment (the trochoid inner envelope is superimposed).

FIG. 4 is a partially enlarged mesh diagram of the external gear and the internal gear of the embodiment.

FIG. 5 is a view showing a state in which the rotational phase is slightly shifted from FIG. 4;

FIG. 6 is a cross-sectional view showing the entire configuration of an example of a flexion-type gear meshing structure common to one embodiment of the present invention and the prior art.

FIG. 7 is a sectional view taken along line VII-VII of FIG. 6 in a conventional structure.

FIG. 8 is a meshing diagram of a conventional external gear and internal gear.

FIG. 9 is an enlarged view of the tooth profile (epitrochoid parallel curve) of the external gear of the external gear of the conventional planetary gear reducer (difference in number of teeth: 1).

FIG. 10 is an enlarged view of a tooth profile (trochoid internal envelope) of an internal gear of an internal gear of a conventional planetary gear reducer (difference in number of teeth: 1).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Input shaft (1st axis) 2 ... Output shaft (2nd axis) 3a, 3b ... Eccentric body 5a, 5b ... External gear 109 ... External tooth 10 ... Internal gear 111 ... Internal tooth

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F16H 1/32

Claims (1)

(57) [Claims] 1. A first shaft, a plurality of external gears mounted eccentrically rotatable with respect to the first shaft via an eccentric body provided on the first shaft, and the external gear Wherein the internal gear meshes with the internal gear, and a second shaft connected to the external gear via means for transmitting only the rotation component of the external gear. The difference between the number of teeth of the external gear and the internal gear is N (N: an integer of 2 or more), and the tooth shape of the external gear is the innermost part formed when N epitrochoid parallel curves are superposed with their phases shifted. constituted by curves, also the innermost as possible when the tooth profile of the internal gear and the epitrochoid parallel curve meshing with the N trochoid in envelope superimposed by shifting as many phases as the external gear internally meshing planetary gear structure characterized by being configured by the curve