JP2020094630A - Planetary gear device - Google Patents

Abstract

To provide a planetary gear device that can suppress dynamic load on each planetary gear and equalize static load, provided that a planetary gear with a large eccentric error is used.MEANS FOR SOLVING THE PROBLEM: A planetary gear device includes: a sun gear; multiple planetary gears arranged so as to simultaneously engage the sun gear in the same phase; and an internal gear arranged so as to engage the multiple planetary gears. The planetary gear device is assembled so that a tooth of each planetary gear where cumulative pitch error becomes the largest starts engaging a tooth of another planetary gear by being dislocated each other by a teeth number that is obtained by dividing a tooth number Z of a planetary gear by the number P of planetary gears.SELECTED DRAWING: Figure 1

Description

The present invention relates to a planetary gear device.

First, a conventional planetary gear device will be described with reference to FIG. The planetary gear device illustrated here is of a so-called star type mainly composed of a sun gear 21, a plurality of planetary gears 22 (22a, 22b, 22c), a planet carrier 23 (23a, 23b), and an internal gear 24. It is a planetary gear device 20 having a defined structure. The planetary gear 22 is manufactured by eccentricizing the rotation center thereof by a predetermined amount, and this eccentricity causes a cumulative pitch error (eccentricity error) described later.

The planetary gear device 20 transmits the rotational driving force as follows. That is, for example, in the case of a planetary gear device for a gas turbine, when the input shaft 25 connected to the gas turbine that is the power source is rotationally driven, the sun gear 21 integrated with the input shaft 25 also rotates at the same time and meshes therewith. The planetary gear 22 is rotationally driven. Further, an internal gear 24 meshing with the planetary gear 22 is rotationally driven, and an output shaft meshed with the internal gear 24 transmits the rotation to a driven machine such as a generator.

Since the planetary gear device for such a gas turbine has a high pitch circumferential speed, it has a feature that torsional vibration caused by the meshing of gears is large as compared with a gear device for general industry. Since this torsional vibration causes a dynamic load on the tooth surface, its reduction is required.

The excitation force that causes the torsional vibration is generated by the advance/lag of the driven gear with respect to the drive gear, that is, a transmission error. The transmission error occurs due to the variation in the rigidity of the teeth as the meshing progresses and the manufacturing error of the gear.

As a planetary gear device that reduces this transmission error, the one described in Patent Document 1 is known, and in Patent Document 1, when the eccentricity error direction of the planetary gear is viewed in a cross section perpendicular to the device axis, all are predetermined. The transmission error is reduced by assembling in the direction of.

JP-A-11-280853

However, in the configuration of Patent Document 1, in order to reduce the transmission error as expected, it is necessary to make the waveform formed by connecting the cumulative pitch error (eccentricity error) of one revolution of each planetary gear the same. Highly accurate and expensive manufacturing technology is required. For this reason, due to circumstances such as cost reduction, if the machining accuracy is poor and the planetary gears have different cumulative pitch error waveforms, and there is no choice but to use a planetary gear with pitch error variations between teeth, etc. However, the transmission error cannot be reduced as expected, and a large dynamic load due to a large torsional vibration may be generated in each planetary gear, or a static load carried by each planetary gear may be significantly biased.

Therefore, in the present invention, even if the planetary gears have different cumulative pitch error waveforms and the pitch error varies among the teeth, the dynamic load applied to each planetary gear is suppressed. It is an object of the present invention to provide a planetary gear device capable of performing a uniform load evenly.

To solve the problem, for example, the structure described in the claims is adopted.

To give an example thereof, a sun gear, a plurality of planet gears arranged so as to mesh with the sun gear at the same time, and an internal gear arranged so as to mesh with the plurality of planet gears are provided. In the planetary gear device, the teeth having the maximum cumulative pitch error of each planetary gear are assembled such that the teeth are shifted by the number of teeth Z of the planetary gear divided by the number p of the planetary gears to start meshing.

According to the planetary gear device of the present invention, even if a planetary gear having a large eccentricity error is used, it is possible to suppress the dynamic load applied to each planetary gear and equalize the static load.

It is a structural diagram explaining the structure of the conventional planetary gear device. FIG. 3 is a plan view illustrating a main part of the planetary gear device according to the first embodiment. FIG. 5 is a diagram illustrating cumulative pitch error of each planetary gear according to the first embodiment. FIG. 8 is a diagram illustrating a second embodiment. It is a figure explaining Example 3. It is a figure explaining Example 4.

Hereinafter, the planetary gear device of the present invention will be described with reference to the drawings. In each embodiment, the same reference numerals are used for the same components.

The planetary gear device 20 according to the first embodiment of the present invention will be described with reference to FIGS. 2 and 3. It should be noted that redundant description is omitted for the common points with FIG.

FIG. 2 is a plan view in which, out of the configurations illustrated in FIG. 1, the configurations necessary for explaining the features of the planetary gear 22 of the present embodiment are extracted. Each of the planetary gears 22 shown here is a gear having Z teeth, and the teeth are numbered from #1 to #Z in the direction opposite to the rotation direction. In this embodiment, the sun gear 21, the planetary gear 22, the internal gear 24, etc. are designed so that all the meshing parts of the sun gear 21 and the planetary gear 22 are simultaneously meshed in the same phase. The number of teeth of the gear 21 is 18, the number of teeth of the planetary gear 22 is 36, the number of teeth of the internal gear 24 is 90, and the number of the planetary gears 22 is 3.

Here, let us consider a state in which an arbitrary tooth #n (1≦n≦Z) of the planetary gear 22a meshes with a tooth of the sun gear 21 at a pitch point. As described above, in the planetary gear device 20 of the present embodiment, since all meshing portions simultaneously mesh with the same phase, when the teeth #n of the planetary gear 22a mesh with the sun gear 21, the planetary gears 22b and 22c also. Since they mesh with the sun gear 21, the teeth of these planetary gears are also given the tooth numbers #n in the following.

Next, a method of determining the tooth #1 of the planetary gear 22a will be described.

Reference numerals 3a, 3b and 3c shown in FIG. 3 are cumulative pitch errors of the planetary gears 22a, 22b and 22c. In this embodiment, the planetary gear device 20 is assembled so that the characteristics finally shown in FIG. 3 are obtained. Tooth #A, tooth #B, and tooth #C shown below the horizontal axis have the maximum cumulative pitch error 3a, the maximum cumulative pitch error 3b, and the maximum cumulative pitch error 3c, respectively. The tooth #A having the maximum value of the cumulative pitch error 3a is defined as tooth #1 hereinafter.

When the tooth #1 of the planetary gear 22a is defined in this way, the tooth #B of the planetary gear 22b and the tooth #C of the planetary gear 22c can be determined by the following equations 1 and 2.

However, Z is the number of teeth of the planetary gear, and p is the number of planets (“3” in the example of FIG. 2). If Z is not a multiple of p, the values corrected to integers by raising or lowering are set as #B and #C.

The planetary gear device 20 in which the teeth #1, teeth #B, and teeth #C of the planetary gear 22 are determined in this manner is preferably manufactured as follows.

First, for example, a column tube made of carbon steel for machine structure or alloy steel for machine structure is leveled to manufacture a gear blank. Next, teeth are formed by gear cutting such as hobbing. As a result, the planetary gear 22 is almost completed, but thereafter, heat treatment may be performed, and finally, finish processing such as grinding may be performed.

When all of the planetary gears 22 incorporated in the planetary gear device 20 are completed, the pitch error of the tooth surface of the planetary gears 22 is measured. Then, the cumulative pitch error is calculated based on the measured pitch error, and some mark is provided on each tooth having the maximum cumulative pitch error.

The planetary gear 22 selected as the planetary gear 22a is assembled so that the marked teeth mesh with the sun gear 1. Further, the planetary gear 22 selected as the planetary gear 22b is assembled so that the tooth separated from the marked tooth by #B in the reverse rotational direction meshes with the sun gear 1, and the planetary gear 22 selected as the planetary gear 22c is Assemble so that the tooth that is #C away from a certain tooth in the reverse rotation direction meshes with the sun gear 1.

By assembling the planetary gear device 20 in this manner, the cumulative pitch error of the planetary gear 22 is maximized at tooth #1 in the planetary gear 22a, maximized at tooth #B in the planetary gear 22b, and is increased at planetary gear 22c. Is the maximum at tooth #C, so that the characteristics shown in FIG. 3 can be obtained.

As a result, in the planetary gear device of the present embodiment, the transmission error generated due to the accumulated pitch error differs between the planetary gears, so that the transmission error in the entire planetary gear device can be reduced. As a result, the exciting force can be reduced and the torsional vibration can be reduced.

Next, a planetary gear device according to a second embodiment of the present invention will be described with reference to FIG. It should be noted that redundant description is omitted for the common points with the first embodiment.

In the first embodiment, the variation in the pitch error between the teeth of the planetary gear 22 is neglected. Therefore, in FIG. 3, the cumulative pitch errors 3a to 3b are shown as smooth sinusoidal waveforms. However, in reality, since there is a variation in the pitch error between the teeth of the planetary gear 22, it is necessary to consider this variation.

In view of this, the present embodiment aims to obtain the same effect as that of the first embodiment even if there is a variation in pitch error between the teeth of each planetary gear 22.

FIG. 4 shows cumulative pitch errors 4a, 4b, 4c of the planetary gears 22a, 22b, 22c when the pitch error between the teeth varies. The meanings of #1, #B, and #C are the same as in the first embodiment.

In the second embodiment, tooth #B and tooth #C are determined as follows.

First, the cumulative pitch error at any tooth #n of the planetary gears 22a, 22b, 22c is Fpa(n), Fpb(n), Fpc(n), and the sum of squared deviations thereof is S(n). Then, S(n) is obtained by the following Expression 3.

In addition,

Is the average value of Fpa(n), Fpb(n), and Fpc(n). Here, the average value Save of the sum of squared deviations is defined as in the following Expression 4.

Then, the combination of #1, #B, and #C that maximizes the average value Save of the sum of squared deviations obtained by Expression 4 is adopted, and the planetary gear device 20 is assembled in the same procedure as in the first embodiment.

By adopting the assembling method that maximizes the sum of squared deviations of the cumulative pitch error in this way, even if there is variation in pitch error between teeth that was not considered in Example 1, As in the case of 1, it is possible to realize the suppression of torsional vibration.

Next, a planetary gear device according to a third embodiment of the present invention will be described with reference to FIG. It should be noted that duplicated description is omitted for common points with the above-described embodiment.

In the first and second embodiments, the planetary gear device 20 is assembled so that the tooth #1, the tooth #B, and the tooth #C in each planetary gear 22 are set at substantially equal intervals, and thus torsional vibration, that is, the planetary gear 22 Although the dynamic load applied to the planetary gears 22 is suppressed, the present embodiment aims to equalize the static load applied to each planetary gear 22.

FIG. 5 shows cumulative pitch errors 5a, 5b, 5c of the planetary gears 22a, 22b, 22c. Also in this embodiment, the meanings of #1, #B and #C are the same as in the first embodiment.

In the third embodiment, tooth #B and tooth #C are determined as follows.

That is, the combination of #1, #B, and #C that minimizes the average value Save of the sum of squared deviations calculated from the above-described formulas 3 and 4 is adopted, and the planetary gear device is performed in the same procedure as in the first embodiment. Assemble 20.

In this way, if the assembly method that minimizes the sum of squared deviations of the cumulative pitch error is adopted, #B and #C are close to #1 as shown in FIG. In this case, the transmission error generated due to the accumulated pitch error is approximated between the planetary gears, so the transmission error in the entire planetary gear device cannot be reduced and torsional vibration cannot be reduced, but the load between the planetary gears cannot be reduced. Can be evenly distributed.

Next, a planetary gear device according to a fourth embodiment of the present invention will be described with reference to FIG. It should be noted that duplicated description is omitted for common points with the above-described embodiment.

The planetary gear devices of Examples 1 to 3 were designed such that all the meshing portions of the sun gear 21 and the planetary gear 22 are simultaneously meshed in the same phase, but the planetary gear devices of Example 4 are different from each other. This is a planetary gear device in which the meshing portions have the same phase but do not mesh simultaneously, but mesh one after another. For example, the number of teeth of the sun gear 21 is 19, the number of teeth of the planetary gear 22 is 37, the number of teeth of the internal gear is 92, and the number of planetary gears is 3.

FIG. 6 shows the cumulative pitch errors 6a, 6b, 6c of the planetary gears 22a, 22b, 22c when the meshing portions mesh with each other one after another. The meanings of #1, #B, and #C are the same as in the first embodiment.

In the fourth embodiment, #B and #C are determined as follows.

That is, the combination of #1, #B, and #C that minimizes the average value Save of the sum of squared deviations calculated from the above-described formulas 3 and 4 is adopted, and the planetary gear device is performed in the same procedure as in the first embodiment. Assemble 20.

In this way, by adopting the assembling method that minimizes the sum of squared deviations of the accumulated pitch error, even in the planetary gear device in which the meshing portions do not mesh at the same phase, the loads between the planetary gears can be equally distributed.

3a to 3c, 4a to 4c, 5a to 5c, 6a to 6c... Cumulative pitch error 20... Planetary gear device,
21... sun gear,
22, 22a, 22b, 22c... Planetary gears,
23, 23a, 23b... planet carrier,
24... Internal gear,
25... Input shaft,

Claims (4)

A planetary gear device comprising a sun gear, a plurality of planetary gears arranged to mesh with each other in the same phase as the sun gear, and an internal gear arranged to mesh with the plurality of planetary gears,
A planetary gear device characterized in that the teeth having the maximum cumulative pitch error of each planetary gear are shifted by the number of teeth Z of the planetary gear divided by the number p of planetary gears to start meshing. A planetary gear device comprising a sun gear, a plurality of planetary gears arranged to mesh simultaneously with the sun gear in the same phase, and an internal gear arranged to mesh with the plurality of planetary gears,
A planetary gear device, characterized in that it is assembled so that the average value of the sum of squared deviations of the cumulative pitch error of each planetary gear is maximized. A planetary gear device comprising a sun gear, a plurality of planetary gears arranged to mesh simultaneously with the sun gear in the same phase, and an internal gear arranged to mesh with the plurality of planetary gears,
A planetary gear device, characterized in that it is assembled so that the average value of the sum of squared deviations of the cumulative pitch error of each planetary gear is minimized. A planetary gear device comprising a sun gear, a plurality of planetary gears arranged to mesh with the sun gear one after another, and an internal gear arranged to mesh with the plurality of planetary gears,
A planetary gear device, characterized in that it is assembled so that the average value of the sum of squared deviations of the cumulative pitch error of each planetary gear is minimized.

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