JP7177680B2 - planetary gear - Google Patents

Description

The present invention relates to a planetary gear system.

First, a conventional planetary gear device will be described with reference to FIG. The planetary gear device exemplified here is mainly composed of a sun gear 21, a plurality of planetary gears 22 (22a, 22b, 22c), planetary carriers 23 (23a, 23b), and an internal gear 24. A planetary gear set 20 of defined structure. The planetary gear 22 is manufactured with its center of rotation eccentric by a predetermined amount, and this eccentricity causes an accumulated pitch error (eccentric error), which will be described later.

This planetary gear device 20 transmits 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, which is the power source, is driven to rotate, the sun gear 21 integrated therewith also rotates at the same time and meshes with it. The planetary gear 22 is rotationally driven. Furthermore, the internal gear 24 meshing with the planetary gear 22 is rotationally driven, and the output shaft meshing with it transmits the rotation to a driven machine such as a generator.

Since such planetary gear systems for gas turbines have a high pitch circumferential velocity, they are characterized by large torsional vibrations caused by the meshing of the gears compared to general industrial gear systems. Since this torsional vibration generates a dynamic load on the tooth surface, it is required to be reduced.

The vibratory force that causes torsional vibration is generated by the lead/lag of the driven gear with respect to the drive gear, that is, the transmission error. The transmission error is caused by tooth rigidity variation as meshing progresses and gear manufacturing error.

As a planetary gear device that reduces this transmission error, the one described in Patent Document 1 is known. 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 same waveform formed by connecting the accumulated pitch error (eccentric error) for one revolution of each planetary gear. , high-precision and expensive manufacturing technology is required. For this reason, due to circumstances such as cost reduction, there is no choice but to use planetary gears that have poor machining accuracy, have different waveforms of accumulated pitch errors depending on each planetary gear, and have variations in pitch error between teeth. In some cases, the transmission error cannot be reduced as expected, and a large dynamic load due to large torsional vibration is generated in each planetary gear, or the static load borne by each planetary gear is significantly unbalanced.

Therefore, in the present invention, the dynamic load applied to each planetary gear is suppressed even if the waveform of the accumulated pitch error is different for each planetary gear and even if planetary gears with variations in pitch error between teeth are used. It is an object of the present invention to provide a planetary gear device capable of equalizing static loads.

In order to solve the problem, for example, the structure described in the claims is adopted.

For example, it comprises a sun gear, a plurality of planetary gears arranged to simultaneously mesh with the sun gear in the same phase, and an internal gear arranged to mesh with the plurality of planetary gears. The planetary gear device is assembled so that the tooth of each planetary gear having the maximum accumulated pitch error shifts by the number of teeth Z of the planetary gear divided by the number p of the planetary gears and meshing starts.

According to the planetary gear device of the present invention, even if planetary gears with a large eccentricity error are used, the dynamic load applied to each planetary gear can be suppressed and the static load can be equalized.

It is a structural drawing explaining the structure of the conventional planetary gear apparatus. FIG. 2 is a plan view illustrating the essential parts of the planetary gear device of Example 1; 4 is a diagram illustrating cumulative pitch errors of planetary gears of Example 1. FIG. FIG. 11 is a diagram for explaining Example 2; FIG. 11 is a diagram for explaining Example 3; FIG. 11 is a diagram for explaining Example 4;

The planetary gear device of the present invention will be described below with reference to the drawings. In addition, in each embodiment, the same symbols are used for the same components.

A planetary gear device 20 according to Embodiment 1 of the present invention will be described with reference to FIGS. 2 and 3. FIG. Duplicate descriptions of the points in common with FIG. 1 will be omitted.

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

Here, consider a state in which an arbitrary tooth #n (1≤n≤Z) of the planetary gear 22a meshes with the tooth of the sun gear 21 at the pitch point. As described above, in the planetary gear device 20 of this embodiment, all of the meshing portions are meshed in the same phase at the same time. Since they mesh with the sun gear 21, the teeth of those planetary gears are also numbered #n below.

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

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 as to finally obtain the characteristics shown in FIG. Tooth #A, tooth #B, and tooth #C shown below the horizontal axis are the teeth with the maximum cumulative pitch error 3a, the maximum cumulative pitch error 3b, and the maximum cumulative pitch error 3c. The tooth #A, which is the tooth with the maximum cumulative pitch error 3a, is hereinafter defined as the tooth #1.

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 planetary gears ("3" in the example of FIG. 2). If Z is not a multiple of p, the values corrected to integers by rounding up or down are #B and #C.

The planetary gear train 20 having teeth #1, #B, and #C of the planetary gears 22 determined in this way is preferably manufactured as follows.

First, for example, a column tube made of carbon steel for machine structural use or alloy steel for machine structural use is normalized to produce a gear blank. The teeth are then formed, for example by a gear cutting process such as hobbing. As a result, the planetary gear 22 is almost completed. After that, heat treatment may be performed, and finally, finishing such as grinding may be performed.

When all the planetary gears 22 incorporated in the planetary gear device 20 are completed, the pitch errors of the tooth flanks of the planetary gears 22 are measured. A cumulative pitch error is then calculated based on the measured pitch errors, and a mark is provided on each tooth having the maximum cumulative pitch error.

Then, the planetary gear 22 selected as the planetary gear 22a is assembled so that the marked tooth meshes with the sun gear 1. As shown in FIG. The planetary gear 22 selected as the planetary gear 22b is assembled so that the tooth #B apart from the tooth with the mark in the opposite direction of rotation meshes with the sun gear 1, and the planetary gear 22 selected as the planetary gear 22c is assembled with the tooth with the mark. It is assembled so that the tooth #C away from a certain tooth in the opposite direction of rotation meshes with the sun gear 1.

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

As a result, in the planetary gear device of this embodiment, the transmission error caused by the cumulative pitch error differs among the planetary gears, so that the transmission error in the entire planetary gear device can be reduced. As a result, the vibrating force can be reduced, and the torsional vibration can be reduced.

Next, a planetary gear device according to Embodiment 2 of the present invention will be described with reference to FIG. Duplicate descriptions of common points with the first embodiment will be omitted.

In Example 1, variations in the pitch error between the teeth of the planetary gear 22 are ignored, so in FIG. 3 the cumulative pitch errors 3a-3b are shown as smooth sinusoidal waveforms. However, in reality, there is variation in the pitch error between the teeth of the planetary gear 22, so it is necessary to consider this variation.

Therefore, in the present embodiment, it is an object to obtain the same effect as in the first embodiment even when the planetary gears 22 have variations in the pitch error between the teeth.

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

In Example 2, tooth #B and tooth #C are determined as follows.

First, let Fpa(n), Fpb(n), and Fpc(n) be the cumulative pitch errors at any tooth #n of the planetary gears 22a, 22b, and 22c, respectively, and let S(n) be the sum of squares of these deviations. Then, S(n) is obtained by Equation 3 below.

note that,

is the average value of Fpa(n), Fpb(n) and Fpc(n). Here, the average value Save of the sum of squares of deviations is defined as in Equation 4 below.

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

By adopting the assembly method that maximizes the sum of squared deviations of the accumulated pitch errors in this way, even if there is variation in the pitch error between the teeth, which was not taken into consideration in the first embodiment, the present embodiment can Similar to 1, suppression of torsional vibration can be realized.

Next, a planetary gear device according to Embodiment 3 of the present invention will be described with reference to FIG. Duplicate descriptions of the points in common with the above-described embodiment will be omitted.

In Embodiments 1 and 2, the planetary gear device 20 is assembled so that the teeth #1, teeth #B, and teeth #C in each planetary gear 22 are set at approximately equal intervals, thereby torsional vibration, that is, the planetary gears 22 Although the dynamic load applied to the planetary gears 22 is suppressed, the purpose of this embodiment is to equalize the static load applied to each planetary gear 22 .

FIG. 5 shows the 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 Example 3, tooth #B and tooth #C are determined as follows.

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

In this way, when the assembling method that minimizes the sum of squared deviations of the accumulated pitch errors is adopted, #B and #C are close to #1 as shown in FIG. In this case, since the transmission error caused by the cumulative pitch error is approximated between the planetary gears, the transmission error in the entire planetary gear system cannot be reduced, and the torsional vibration cannot be reduced. can be equally distributed.

Next, a planetary gear device according to Embodiment 4 of the present invention will be described with reference to FIG. Duplicate descriptions of the points in common with the above-described embodiment will be omitted.

The planetary gear devices of Examples 1 to 3 were designed so that all the meshing portions of the sun gear 21 and the planetary gears 22 meshed in the same phase at the same time. It is a planetary gear device in which the meshing portions do not mesh simultaneously in the same phase, but mesh one after another. For example, the sun gear 21 has 19 teeth, the planetary gear 22 has 37 teeth, the internal gear has 92 teeth, and the planetary gear has 3 teeth.

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

In Example 4, #B and #C are determined as follows.

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

Thus, by adopting an assembly method that minimizes the sum of squared deviations of accumulated pitch errors, it is possible to evenly distribute the load between the planetary gears even in a planetary gear device in which the meshing portions do not mesh simultaneously in the same phase.

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 (3)

A planetary gear device comprising a sun gear, a plurality of planetary gears arranged to simultaneously mesh 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 by being assembled so that the average value of the sum of squared deviations of accumulated pitch errors of each planetary gear is maximized. A planetary gear device comprising a sun gear, a plurality of planetary gears arranged to simultaneously mesh 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 by being assembled so as to minimize the average value of the sum of squared deviations of cumulative pitch errors of each planetary gear. a sun gear, a plurality of planetary gears arranged to sequentially mesh with the sun gear, and an internal gear arranged to mesh with the plurality of planetary gears ;
A planetary gear system in which each meshing portion meshes in sequence and does not mesh at the same time in the same phase ,
A planetary gear device characterized by being assembled so as to minimize the average value of the sum of squared deviations of cumulative pitch errors of each planetary gear.

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